This Article Abstract Full Text (PDF) Submit a related Letter to the Editor Purchase Article View Shopping Cart Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Copyright Permission Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Pfeifer, M. Articles by Clayton, R. N. Search for Related Content PubMed PubMed Citation Articles by Pfeifer, M. Articles by Clayton, R. N.

Growth Hormone (GH) Treatment Reverses Early Atherosclerotic Changes in GH-Deficient Adults¹

Department of Endocrinology, Diabetes and Metabolic Diseases (M.P., R.V., J.P.), and the Department of Vascular Diseases (B.., P.P.), University Medical Center, 1000 Ljubljana, Slovenia; and the Department of Medicine, Keele University (R.N.C.), Stoke-on-Trent, Staffordshire, United Kingdom ST4 7QB

Address all correspondence and requests for reprints to: Dr. M. Pfeifer, Department of Endocrinology, Diabetes and Metabolic Diseases, University Medical Center, Zaloka7, 1000 Ljubljana, Slovenia.

	Abstract

Top Abstract Introduction Subjects and Methods Results Discussion References

 
Hypopituitary patients have increased mortality from vascular disease, and in these patients, early markers of atherosclerosis [increased carotid artery intima-media thickness (IMT) and reduced distensibility] are more prevalent. As GH replacement can reverse some risk factors of atherosclerosis, the present study examined the effect of GH treatment on morphological and functional changes in the carotid and brachial arteries of GH-deficient (GHD) adults. Eleven GHD hypopituitary men (24–49 yr old) were treated with recombinant human GH (0.018 U/kg BW·day) for 18 months. IMT of the common carotid artery (CCA) and the carotid bifurcation (CB), and flow-mediated endothelium-dependent dilation (EDD) of the brachial artery were measured by B mode ultrasound before and at 3, 6, 12, and 18 months of treatment, and values were compared with those in 12 age-matched control men. Serum concentrations of lipids, lipoprotein(a), insulin-like growth factor I (IGF-I), and IGF-binding protein-3 (IGFBP-3) were also measured. In GHD men before treatment the IMTs of the CCA [mean(SD), 0.67(0.05) mm] and CB [0.75(0.04) mm] were significantly greater (P < 0.001) than those in control men [0.52(0.07) and 0.65(0.07) mm, respectively]. GH treatment normalized the IMT of the CCA by 6 months [0.53(0.04) mm] and that of the CB by 3 months [0.68(0.05) mm]. The IMT of the carotid artery (CCA and CB) was negatively correlated with serum IGF-I (r = -0.53; P < 0.0001). There was a significant improvement in flow-mediated EDD of the brachial artery at 3 months, which was sustained at 6 and 18 months of GH treatment (P < 0.05). GH treatment increased high density lipoprotein cholesterol at 3 and 6 months, but did not reduce total or low density lipoprotein cholesterol and was without effect on lipoprotein(a). There was no correlation between plasma lipids and changes in IMT or EDD of the arteries examined. In conclusion, GH treatment of hypopituitary GHD men reverses early morphological and functional atherosclerotic changes in major arteries and, if maintained, may reduce vascular morbidity and mortality. GH seems to act via IGF-I, which is known to have important effects on endothelial cell function.

	Introduction

Top Abstract Introduction Subjects and Methods Results Discussion References

 
THERE is considerable interest in the long term outcome of patients with hypopituitarism with respect to life expectancy. From the four retrospective studies performed to date, there appears to be a consistent trend for a 1.5- to 2-fold increase in the ratio of observed/expected mortality from all causes (1, 2, 3, 4). Moreover, two studies (1, 3) suggest a 1.5- to 2-fold increase in vascular mortality, predominantly due to cerebrovascular disease. Bülow et al. showed a 3.4-fold increase in cerebrovascular deaths and a 6.7-fold increase in patients younger than 55 yr at diagnosis (3).

Several risk factors for atherosclerosis are more prevalent in hypopituitary adults, including dyslipidemia (reviewed in Ref. 5), decreased plasma fibrinolytic activity, increased prevalence of hypertension in some (6) but not all (7) studies, increased waist/hip ratio and decreased lean body mass (8), increased peripheral insulin resistance (9), and increased frequency of impaired glucose tolerance (10, 11). These changes may be ameliorated by GH treatment (5, 8, 12). Therefore, it has been assumed that GH deficiency is responsible for early atherogenesis in hypopituitarism, rather than suboptimal nonphysiological replacement with hydrocortisone, T₄, or sex steroids.

Hypopituitary GH-deficient (GHD) adults have been shown to have an increased number of atheromatous plaques in carotid and femoral arteries (11). Increased intima-media thickness (IMT) of carotid arteries has also been shown in these patients (11, 13), even in the absence of classic risk factors for atherosclerosis (13). Intima media thickening represents the earliest morphological change in the arterial wall in the process of atherogenesis (14, 15), and is an independent predictor of acute myocardial infarction in men (16). Increased stiffness of the carotid artery wall (17) and impaired flow-mediated, endothelium-dependent brachial artery dilation (18) suggest functional changes in the arteries of GHD adults.

The aim of this study was to investigate the influence of GH treatment on morphological (IMT) and functional changes [flow-mediated endothelium-dependent dilation (EDD)] in peripheral arteries of hypopituitary GHD patients.

	Subjects and Methods

Top Abstract Introduction Subjects and Methods Results Discussion References

 
Subjects and GH treatment protocol

Eleven hypopituitary men, aged 24–49 (mean, 34) yr, with GH deficiency (GH <2 µg/L with insulin-induced hypoglycemia) participated in this open study. Twelve age-matched (age range 23–47 yr; mean, 31.6 yr) men without evidence of pituitary or vascular disease served as controls. The cause of GH deficiency was a pituitary tumor or a consequence of its treatment in nine patients, 1 had pituitary agenesis, and the other had idiopathic panhypopituitarism. Four of 11 had childhood-onset disease, of whom 2 had received GH, which had been stopped for 15 and 9 yr before the present study. All patients had multiple pituitary hormone deficiencies, and all were receiving optimal substitution therapy, including gonadal hormones as appropriate. The duration of GH deficiency was estimated from the history and ranged from 2–25 yr (mean, 11.6 yr). All patients were normotensive and had normal fasting plasma glucose, and two smoked more than 10 cigarettes/day. The GH (Humatrope, Eli Lilly & Co., Indianapolis, IN) treatment protocol was as follows: 0.009 U/kg BW administered once daily sc for 1 month, then increased to 0.018 U/kg BW for the remainder of the study (17 months). Informed written consent was obtained, and the study was approved by the local ethical committee.

Ultrasonographic assessment of IMT

Carotid ultrasound examination was performed using a high resolution B-mode Diasonics UST ultrasound system (Diasonics Ultrasound, Inc., Mipitas, CA) with a 5-MHz linear array transducer. Carotid arteries of all subjects were visualized by B-mode ultrasound, and the arterial wall was observed in longitudinal section. On the basis of different tissue densities in the B-scan, the layers of the arterial wall were represented as parallel echogenic lines separated by a relatively hypoechoic space (the double line pattern). The distance from the leading edge of the first echogenic line (lumen-intima interface) to the leading edge of the second echogenic line (media-adventitia interface) was considered to be the combined thickness of the intima and media layers.

The B-mode investigation protocol involved scanning the right and the left common carotid arteries (CCA) 1 cm below the bifurcation and the carotid bifurcations (CB). Two angles of interrogation were used: anterolateral, and posterolateral. The image was focused on the posterior (far) wall. The mean IMT was calculated for each subject as the average of three measurements on each segment. The other accessible parts of the carotid arteries were also visualized, and atherosclerotic lesions (plaques) were sought. All measurements were carried out by the same examiner. The intraoperator coefficient of variation of repeated measurements was 5.8%.

Determination of endothelium-dependent dilation of the brachial artery

Flow-mediated EDD was studied noninvasively in the right brachial artery as previously described (19). The subjects rested in the supine position for 10 min before hemodynamic measurements were performed. The brachial artery was scanned in longitudinal section 2–15 cm above the elbow. From B-mode ultrasound images the mean diameter was calculated. Measurements were taken at the end of the diastole incident with the R wave on the continuously recorded electrocardiogram. At least three cardiac cycles were analyzed for each scan, and measurements were averaged. The flow velocity was measured at the fixed incident angle of 68° to the vessel with the range gate 1.5 mm in the center of the artery. The baseline (resting) blood flow was estimated by multiplying the velocity time integral of the Doppler flow signal (corrected for incident angle) and the vessel cross-sectional area. Hyperemic flow increase was induced by inflation of a blood pressure tourniquet, placed around the forearm, to a suprasystolic pressure for 4 min, causing ischemia and vasodilation in the distal forearm. Hyperemic flow was recorded for the first 10 s, and flow-mediated dilation of brachial artery (diameter) was measured 45–60 s after cuff release. The relative flow increase during reactive hyperemia was calculated as the maximum flow recorded during the first 15 s after cuff release divided by the flow during rest. The flow-mediated diameter increase in the brachial artery (EDD) was calculated as the percent change relative to the baseline measurement. The intraoperator coefficient of variation of these measurements was 8.3%.

Biochemical measurements

After an overnight fast, blood was obtained for measurement of triglycerides, total cholesterol, low density lipoprotein (LDL) cholesterol, high density lipoprotein (HDL) cholesterol, lipoprotein(a), insulin-like growth factor I (IGF-I), and IGF-binding protein-3 (IGFBP-3) before treatment and at 3, 6, 12, and 18 months of treatment. Total serum cholesterol, triglycerides, and high density lipoprotein (HDL) cholesterol were measured by commercially available kits (Abbott Laboratories, North Chicago, IL; interassay coefficient of variation, <4%). Serum LDL cholesterol was calculated as previously described (20). Serum lipoprotein(a) was measured by a commercial enzyme-linked immunosorbent assay [TintElizaLp(a), Biopool, Umea, Sweden), serum IGF-I was determined by an immunoradiometric assay (Diagnostic Systems Laboratories, Inc., Webster, TX) with inter- and intraassay coefficients of variation of 3.9–7% and 3.8–7.4%, respectively, and serum IGFBP-3 was determined by a commercial RIA (Diagnostic Systems Laboratories, Inc.) with inter- and intraassay coefficients of variation of 4.2–8.3% and 5.3–6.7%, respectively.

Statistical analysis

Data are expressed as the mean (SD) after each variable was tested for goodness of fit to a normal distribution. EDD and blood flow data were log transformed before statistical analysis. Comparisons between GHD and control subjects were performed by two-tailed unpaired Student’s t test. Comparisons of treatment effects over time were assessed by one-way ANOVA followed by Tukey’s test (IMT) or paired Student’s t test (biochemical, EDD, and blood flow data). Pearson’s correlation analysis and multiple regression analysis were applied to assess the relation of different variables to IMT and EDD.

	Results

Top Abstract Introduction Subjects and Methods Results Discussion References

 
All patients tolerated GH treatment well, and none had to withdraw because of side-effects. There was no difference in blood pressure between patients and controls, and this did not change with GH treatment.

Carotid artery morphology

The results of IMT measurements are shown in Table 1. Before treatment, GHD men had a 20–30% thicker intima-media of the CCA and the CB than age-matched controls. GH treatment induced a decrease in the IMT of the CCA by 3 months, and an additional decrease was seen at 6 months. The values at 6, 12, and 18 months were no longer different from the control values (Fig. 1). A similar reduction in the IMT was seen in the first 6 months at the CB, which was no longer different from the control value by 3 months of treatment (Table 1). No atherosclerotic plaques were observed in the investigated arterial segments in any of the control subjects or GHD men. Univariate regression analysis revealed a significant negative correlation between IMT of the CCA and IGF-I (Fig. 2) and between IMT and IGFBP-3 (r = -0.51; P < 0.0001 and r = -0.38; P < 0.01, respectively). Almost identical and highly significant negative correlations were observed between IMT of the CB and IGF-I and IGFBP-3 (not shown). However, when the multiple regression analysis model was applied, only IGF-I was significantly correlated with IMT (CCA and CB; r = -0.53; P < 0.0001). There were no significant correlations between IMT and plasma lipid values.

View larger version (12K): [in this window] [in a new window]   Figure 1. Changes of intima media thickness (IMT) [mean (SE)] of the common carotid artery (CCA) during GH treatment.

View larger version (14K): [in this window] [in a new window]   Figure 2. Correlation between intima media thickness (IMT) of the common carotid artery (CCA) and serum IGF-I (r = -0.51; P < 0.001).

Before treatment, the flow-mediated endothelium-dependent increase in the diameter of the brachial artery during hyperemia was lower in GHD men than in controls, but the difference was not statistically significant. After 3, 6, and 18 months of GH treatment, EDD significantly improved compared to pretreatment values (P < 0.05; Table 2). The blood flow increase in the brachial artery after hyperemia was significantly lower in patients before treatment compared to controls (P < 0.05) and reached the control values after 6 months of GH treatment (Table 2). The 12 month values of EDD and blood flow are inexplicably low and do not fit into the general trend of improvement with GH treatment. There was no correlation between IGF-I or IGFBP-3 or lipid levels and either EDD or blood flow.

Lipid and IGF responses to GH treatment are shown in Tables 3 and 4. Before treatment, GHD men had significantly higher triglyceride and lower HDL cholesterol concentrations and HDL/LDL ratio compared to controls (Table 3). Total and LDL cholesterol levels were not significantly different. Triglycerides remained significantly greater, and the HDL/LDL ratio remained significantly lower in GHD adults throughout the 18-month treatment period. Total cholesterol was significantly greater than control values at 3, 6, and 18 months of treatment. Compared to pretreatment values, there were no significant changes over the 18-month period in total cholesterol, LDL cholesterol, triglyceride, or lipoprotein(a) concentrations. However, HDL cholesterol increased significantly (P < 0.01) after 3 and 6 months.

	Discussion

Top Abstract Introduction Subjects and Methods Results Discussion References

 
Increased IMT of carotid and femoral arteries represents an early change in the process of atherogenesis (14, 15) and predicts the development of atherosclerotic vascular disease (16, 21, 22). Patients with hypopituitarism have an increased risk of death from cerebrovascular disease compared with an age-matched cohort from the same population (3). Hence, the detection of preclinical structural abnormalities of carotid arteries, which represent an early stage of atherosclerosis (11, 13), and any intervention that could reverse these abnormalities, may have the potential to reduce long term (cerebro)vascular disease incidence.

The data from the present study are the first to demonstrate that GH treatment is capable of reversing the increased IMT of the carotid arteries in GHD hypopituitary adults within a relatively short period. Indeed, the values of IMT after 6 months of treatment were no longer different from those in healthy control men of the same age. Moreover, this beneficial effect is maintained for at least 18 months at both carotid artery sites examined. There was also a beneficial effect of GH treatment on flow-mediated EDD of the brachial artery, although this was more variable due to large inter- and intrasubject variability. Nevertheless, there was a significant increase in this functional response of the brachial artery after 3, 6, and 18 months of treatment. This is consistent with the preliminary results of Evans et al. (18). Furthermore, Markussis et al. (17) showed reduced distensibility of carotid arteries in asymptomatic GHD adults, although this trial did not examine the effect of GH treatment. In addition, in our study the decreased response of brachial artery blood flow to hyperemia in GHD compared to control men was also reversed after 18 months of treatment. Taken together, these results indicate that in GHD adults the vasodilatory function of the endothelium is impaired and improves with GH treatment.

The mechanism(s) by which GH mediates morphological and functional changes in major arteries is not fully understood. Intima media thickening occurs in young adults with childhood-onset GH deficiency in the absence of major risk factors for atherosclerosis, such as abnormal plasma cholesterol, LDL or HDL cholesterol, triglycerides, lipoprotein(a), insulin resistance, or increased fibrinogen (13). The reduction of IMT in our patients was unrelated to changes in plasma lipids, but was clearly related to increases in IGF-I levels. Although we could not find a correlation, it is tempting to speculate that functional changes in arteries are also mediated through the effects of IGF-I on endothelial cell function. It has been shown that nitric oxide (NO) generation is reduced in GHD adults and that GH treatment increases endothelial NO production (23). NO has been identified as a paracrine mediator of vasodilation, inhibition of platelet aggregation and leukocyte adhesion, and inhibition of vascular smooth muscle cell growth (24). L-Arginine enhances endothelial NO production and attenuates or reverses cholesterol-induced atherogenesis in rabbits, although high serum cholesterol levels remain unchanged (25, 26, 27, 28). Moreover, in hypercholesterolemic humans, mononuclear cell adhesiveness (29) and platelet aggregation (30) are also normalized by dietary L-arginine. These data strongly support a role for NO, independent of plasma lipids, in the regression of atherosclerosis. Endothelial cell NO generation is increased by IGF-I (31), IGF-I vascular effects are endothelium dependent (32), and endothelial cells possess IGF-I receptors (33). Thus, IGF-I is an excellent candidate as a mediator of the antiatherogenic effects of GH via its actions on endothelial cell NO production. The negative correlation observed between IMT and IGF-I supports such a mechanistic explanation. Accordingly, it is important to correlate the effects of GH treatment on IMT and EDD to specific biochemical markers of endothelial cell function in GHD adults.

The role of plasma lipid abnormalities in the pathogenesis of atherosclerosis in GHD adults is still controversial. We could not show any relationship between IMT or EDD changes and plasma lipids either before or during GH treatment and therefore conclude that lipid changes are unlikely to make a major contribution to the reduction of early atherosclerotic changes observed in the first 6 months of GH treatment. Most studies have shown that total cholesterol and LDL cholesterol are increased, and HDL cholesterol decreased in GHD adults compared to those in age- and sex-matched controls (reviewed in Refs. 5, 8). In our study there was no difference in total and LDL cholesterol between patients and controls, but HDL cholesterol was reduced. However, reports of changes in lipid concentrations during GH treatment are inconsistent, with some showing significant reductions in total cholesterol and LDL cholesterol (34, 35) and others showing no such change (12, 36). The reports on the effects of GH on HDL cholesterol are also conflicting, showing either no change (34, 35, 37) or a slight increase after long term treatment (12, 36, 38).

We showed that HDL cholesterol increased significantly as early as 3 months after starting GH treatment, earlier than in previous reports, suggesting an important role of GH in modifying this antiatherogenic lipid. With regard to lipoprotein(a), a more recently described risk factor for atherosclerosis, we could not demonstrate any change consistent with other short term (35) and long term (37) studies.

In conclusion, we have demonstrated an important effect of GH treatment in restoring increased IMT, an early morphological marker of atherogenesis, to normal values in GHD hypopituitary men. As expected, we have also shown an improvement of endothelial function, namely an increase in flow-mediated dilation of the brachial artery, with GH treatment. Morphological changes were IGF-I dependent, but independent of plasma lipids and lipoprotein(a). These effects of GH treatment, if maintained long term, may have a beneficial effect on vascular morbidity and mortality in GHD adults.

	Acknowledgments

 
We thank Eli Lilly & Co. for supplies of recombinant hGH, the Department of Nuclear Medicine for performing the IGF-I and IGFBP-3 assays, and the Institute of Clinical Chemistry and Clinical Biochemistry, University Medical Center (Ljubljana, Slovenia) for the plasma lipid analyses.

	Footnotes

 
¹ This work was supported in part by Grant J3–7895-312–96 from the Ministry of Science and Technology of the Republic of Slovenia.

Received July 6, 1998.

Revised October 21, 1998.

Accepted October 29, 1998.

	References

Top Abstract Introduction Subjects and Methods Results Discussion References

 

1. Rosen T, Bengtsson BÅ. 1990 Premature mortality due to cardiovascular disease in hypopituitarism. Lancet. 336:285–288.[CrossRef][Medline]
2. Bates AS, Van’t Hoff W, Jones PJ, Clayton RN. 1996 The effect of hypopituitarism on life expectancy. J Clin Endocrinol Metab. 81:1169–1172.[Abstract]
3. Bülow B, Hagmar L, Mikoczy Z, Nordstrom CH, Erfurth EM. 1997 Increased cerebrovascular mortality in patients with hypopituitarism. Clin Endocrinol (Oxf). 46:75–81.[CrossRef][Medline]
4. Bates AS, Bullivant B, Clayton RN, Sheppard MC, Stewart PM. 1997 Increased mortality in hypopituitarism is not due to an increase in vascular mortality. J Endocrinol. 152(Suppl):0C9.
5. DeBoer H, Blok GJ, van der Veen EA. 1995 Clinical aspects of growth hormone deficiency in adults. Endocr Rev. 16:63–86.[CrossRef][Medline]
6. Wuster C, Slenczka E, Ziegler R. 1991 Increased prevalence of osteoporosis and arteriosclerosis in patients with conventionally substituted pituitary insufficiency: is there a need for additional growth hormone substitution? Klin Wochenschr. 69:769–773.[CrossRef][Medline]
7. Dunne FP, Elliot P, Gammage MD, et al. 1995 Cardiovascular function and glucocorticoid replacement in patients with hypopituitarism. Clin Endocrinol (Oxf). 43:623–629.[Medline]
8. Caroll PV, Christ ER, members of the Growth Hormone Research Society Scientific Committee. 1998 Growth hormone deficiency in adulthood and the effect of growth hormone replacement: a review. J Clin Endocrinol Metab. 83:382–395.[Abstract/Free Full Text]
9. Johansson JO, Fowelin J, Landin K, Larger J, Bengtsson BÅ. 1995 Growth hormone deficient adults are insulin resistant. Metabolism. 44:1126–1129.[CrossRef][Medline]
10. Merimee TJ, Rabinowitz D, Pimoin DL, McKusick VA. 1968 Isolated human growth hormone deficiency. III. Insulin secretion in sexual ateliotic dwarfism. Metabolism. 17:1005–1011.[CrossRef][Medline]
11. Markussis V, Beshyah SA, Fisher C, Sharp P, Nicolaides AN, Johnston DG. 1992 Detection of premature atherosclerosis by high resolution ultrasonography in symptom free hypopituitary adults. Lancet. 340:1188–1192.[CrossRef][Medline]
12. Hwu C-M, Kwok C F, Lai T-Y, et al. 1997 Growth hormone (GH) replacement reduces body fat and normalizes insulin sensitivity in GH deficient adults: a report of one year clinical experience. J Clin Endocrinol Metab. 82:3285–3292.[Abstract/Free Full Text]
13. Capaldo B, Patti L, Oliviero U, et al. 1997 Increased arterial intima-media thickness in childhood onset growth hormone deficiency. J Clin Endocrinol Metab. 82:1378–1381.[Abstract/Free Full Text]
14. Geroulakos G, O’Gorman D, Nicolaides A, Sheridan D, Elkeles RS, Sharper AG. 1994 Carotid intima-media thickness: correlation with the British Regional Heart Study risk score. J Intern Med. 235:431–433.[Medline]
15. Grobbee D, Bots M. 1994 Carotid artery intima-media thickness as an indicator of generalised atherosclerosis. J Intern Med. 236:567–573.
16. Salonen JT, Salonen R. 1993 Ultrasound B-mode imaging in observational studies of atherosclerosis progression. Circulation. 87(Suppl 2):56–65.
17. Markussis V, Beshyah SA, Fisher C, Parker KH, Nicolaides AN, Johnston DG. 1997 Abnormal carotid arterial wall dynamics in symptom free hypopituitary adults. Eur J Endocrinol. 136:157–164.[Abstract/Free Full Text]
18. Evans LM, Davies JS, Rees JAE, Scanlon MF. Endothelial dysfunction (ED) in adult growth hormone deficiency. Proc of the 4th Eur Congr of Endocrinol. 1998; OR1 (Abstract).
19. Celermajer DS, Sorensen KE, Georgakopoulos D, et al. 1993 Cigarette smoking is associated with dose-related and potentially reversible impairment of endothelium dependent dilation in healthy young adults. Circulation. 88:2149–2154.[Abstract/Free Full Text]
20. Friedewald WT, Levy RI, Frederickson DS. 1972 Estimation of the concentration of low density lipoprotein cholesterol in plasma without use of preparative ultracentrifuge. Clin Chem. 18:499–502.[Abstract]
21. Wilson PWF, Hoeg JM, D’Agostino RB, et al. 1997 Cumulative effects of high cholesterol levels, high blood pressure, and cigarette smoking on carotid stenosis. N Engl J Med. 337:516–522.[Abstract/Free Full Text]
22. Gamble G, Zom J, Sanders G, MacMahon S, Sharpe N. 1994 Estimation of arterial stiffness, compliance, and distensibility from M-mode ultrasound measurements of the common carotid artery. Stroke. 25:11–16.[Abstract]
23. Böger RH, Skamira C, Bode-Böger SM, Brabant G, von zur Mühlen A, Frölich JC. 1996 Nitric oxide may mediate the haemodynamic effects of recombinant growth hormone in patients with acquired growth hormone deficiency. J Clin Invest. 98:2706–2713.[Medline]
24. Radomski MW, Salas E. 1995 Nitric oxide–biological mediator, modulator and factor of injury: its role in the pathogenesis of atherosclerosis. Atherosclerosis. 118(Suppl):569–580.
25. Cooke JP, Singer AH, Tsao P, Zera P, Rowan RA, Billingham ME. 1992 Antiatherosclerotic effect of L-arginine in the hypercholesterolaemic rabbit. J Clin Invest. 90:1168–1172.
26. Candipan RC, Wang B, Buitrago R, Tsao PS, Cooke JP. 1996 Regression or progression. Dependency on vascular nitric oxide. Atheroscler Thromb Vasc Biol. 16:44–50.[Abstract/Free Full Text]
27. Singer AH, Tsao PS, Wang B-Y, Bloch DA, Cooke JP. 1995 Discordant effects of dietary L-arginine on vascular structure and reactivity in hypercholesterolaemic rabbits. J Cardiovasc Pharmacol. 25:710–717.[Medline]
28. Böger RH, Bode-Böger SM, Kienke S, Stan AC, Nafe R, Frölich JC. 1998 Dietary L-arginine decreases myointimal cell proliferation and vascular monocyte accumulation in cholesterol-fed rabbits. Atherosclerosis. 136:67–77.[CrossRef][Medline]
29. Theilmeier G, Chan JR, Zalpour C, et al. 1997 Adhesiveness of mononuclear cells in hypercholesterolaemic humans is normalised by dietary L-arginine. Arterioscler Thromb Vasc Biol. 17:3557–3564.[Abstract/Free Full Text]
30. Wolf A, Zalpour C, Theilmeier G, et al. 1997 Dietary L-arginine supplementation normalises platelet aggregation in hypercholesterolaemic humans. J Am Coll Cardiol. 29:478–485.[CrossRef]
31. Tsukahara H, Gordienko DV, Tonshoff B, Gelato MC, Goligorsky MS. 1994 Direct demonstration of insulin-like growth factor 1 induced nitric oxide production by endothelial cells. Kidney Int. 45:598–604.[Medline]
32. Wu HY, Yue CJ, Chyu KY, Hsuch WA, Chan TM. 1994 Endothelium dependent vascular effects of insulin and insulin-like growth factor 1 in the perfused rat mesenteric artery and aortic ring. Diabetes. 43:1027–1032.[Abstract]
33. Bar RS, Boes M, Dake BL, Booth BA, Henley SA, Sandra A. 1988 Insulin, insulin-like growth factors, and vascular endothelium. Am J Med. 85(Suppl 5a):59–70.
34. Cuneo RC, Salomon F, Watts GF, Hesp R, Sönksen PH. 1993 Growth hormone treatment improves serum lipids and lipoproteins in adults with growth hormone deficiency. Metabolism. 42:1519–1523.[CrossRef][Medline]
35. Russell-Jones DL, Watts GF, Weissberger A, et al. 1994 The effect of growth hormone replacement on serum lipids, lipoproteins, apolipoproteins and cholesterol precursors in adult growth hormone deficient patients. Clin Endocrinol (Oxf). 41:345–350.[Medline]
36. Beshyah SA, Henderson A, Niththyananthan R, et al. 1995 The effect of short and long term growth hormone replacement therapy in hypopituitary adults on lipid metabolism an carbohydrate tolerance. J Clin Endocrinol Metab. 80:356–363.[Abstract]
37. Garry P, Collins P, Devlin JG. 1996 An open 36 month study of lipid changes with growth hormone in adults: lipid changes following replacement of growth hormone in adult acquired growth hormone deficiency. Eur J Endocrinol. 134:61–66.[Abstract/Free Full Text]
38. Rosen T, Eden S, Larson G, Wilhelmsen L, Bengtsson BÅ. 1993 Cardiovascular risk factors in adult patients with growth hormone deficiency. Acta Endocrinol (Copenh). 129:195–200.[Medline]

This article has been cited by other articles:

				A. Colao, C. Di Somma, S. Spiezia, S. Savastano, F. Rota, M. C. Savanelli, and G. Lombardi Growth Hormone Treatment on Atherosclerosis: Results of a 5-Year Open, Prospective, Controlled Study in Male Patients with Severe Growth Hormone Deficiency J. Clin. Endocrinol. Metab., September 1, 2008; 93(9): 3416 - 3424. [Abstract] [Full Text] [PDF]

				A. A van der Klaauw, A. M Pereira, T. J Rabelink, E. P M Corssmit, A.-J. Zonneveld, H. Pijl, H. C de Boer, J. W A Smit, J. A Romijn, and E. J P de Koning Recombinant human GH replacement increases CD34+ cells and improves endothelial function in adults with GH deficiency Eur. J. Endocrinol., August 1, 2008; 159(2): 105 - 111. [Abstract] [Full Text] [PDF]

				A. L. Utz, A. Yamamoto, L. Hemphill, and K. K. Miller Growth Hormone Deficiency by Growth Hormone Releasing Hormone-Arginine Testing Criteria Predicts Increased Cardiovascular Risk Markers in Normal Young Overweight and Obese Women J. Clin. Endocrinol. Metab., July 1, 2008; 93(7): 2507 - 2514. [Abstract] [Full Text] [PDF]

				C. Beauregard, A. L. Utz, A. E. Schaub, L. Nachtigall, B. M. K. Biller, K. K. Miller, and A. Klibanski Growth Hormone Decreases Visceral Fat and Improves Cardiovascular Risk Markers in Women with Hypopituitarism: A Randomized, Placebo-Controlled Study J. Clin. Endocrinol. Metab., June 1, 2008; 93(6): 2063 - 2071. [Abstract] [Full Text] [PDF]

				F. Sen, M. Demirturk, N. Abaci, E. Golcuk, H. Oflaz, A. Elitok, F. Kutluturk, H. Issever, N. E. Unaltuna, and N. C. Ozbey Endothelial nitric oxide synthase intron 4a/b polymorphism and early atherosclerotic changes in hypopituitary GH-deficient adult patients Eur. J. Endocrinol., May 1, 2008; 158(5): 615 - 622. [Abstract] [Full Text] [PDF]

				J. L. M. Oliveira, M. H. Aguiar-Oliveira, A. D'Oliveira Jr, R. M. C. Pereira, C. R. P. Oliveira, C. T. Farias, J. A. Barreto-Filho, F. D. Anjos-Andrade, C. Marques-Santos, A. C. Nascimento-Junior, et al. Congenital Growth Hormone (GH) Deficiency and Atherosclerosis: Effects of GH Replacement in GH-Naive Adults J. Clin. Endocrinol. Metab., December 1, 2007; 92(12): 4664 - 4670. [Abstract] [Full Text] [PDF]

				J. K. Devin, L. S. Blevins Jr., D. K. Verity, Q. Chen, J. R. Bloodworth Jr., J. Covington, and D. E. Vaughan Markedly Impaired Fibrinolytic Balance Contributes to Cardiovascular Risk in Adults with Growth Hormone Deficiency J. Clin. Endocrinol. Metab., September 1, 2007; 92(9): 3633 - 3639. [Abstract] [Full Text] [PDF]

				R. C. Kaplan, A. P. McGinn, M. N. Pollak, L. H. Kuller, H. D. Strickler, T. E. Rohan, A. R. Cappola, X. Xue, and B. M. Psaty Association of Total Insulin-Like Growth Factor-I, Insulin-Like Growth Factor Binding Protein-1 (IGFBP-1), and IGFBP-3 Levels with Incident Coronary Events and Ischemic Stroke J. Clin. Endocrinol. Metab., April 1, 2007; 92(4): 1319 - 1325. [Abstract] [Full Text] [PDF]

				T. Thum, S. Hoeber, S. Froese, I. Klink, D. O. Stichtenoth, P. Galuppo, M. Jakob, D. Tsikas, S. D. Anker, P. A. Poole-Wilson, et al. Age-Dependent Impairment of Endothelial Progenitor Cells Is Corrected by Growth Hormone Mediated Increase of Insulin-Like Growth Factor-1 Circ. Res., February 16, 2007; 100(3): 434 - 443. [Abstract] [Full Text] [PDF]

				R. Abs, U. Feldt-Rasmussen, A. F Mattsson, J. P Monson, B.-A. Bengtsson, M. I Goth, P. Wilton, and M. Koltowska-Haggstrom Determinants of cardiovascular risk in 2589 hypopituitary GH-deficient adults - a KIMS database analysis. Eur. J. Endocrinol., July 1, 2006; 155(1): 79 - 90. [Abstract] [Full Text] [PDF]

				J. L. Menezes Oliveira, C. Marques-Santos, J. A. Barreto-Filho, R. Ximenes Filho, A. V. de Oliveira Britto, A. H. Oliveira Souza, C. M. Prado, C. R. Pereira Oliveira, R. M. C. Pereira, T. de Almeida Ribeiro Vicente, et al. Lack of Evidence of Premature Atherosclerosis in Untreated Severe Isolated Growth Hormone (GH) Deficiency due to a GH-Releasing Hormone Receptor Mutation J. Clin. Endocrinol. Metab., June 1, 2006; 91(6): 2093 - 2099. [Abstract] [Full Text] [PDF]

				A. Colao, C. Di Somma, S. Spiezia, F. Rota, R. Pivonello, S. Savastano, and G. Lombardi The Natural History of Partial Growth Hormone Deficiency in Adults: A Prospective Study on the Cardiovascular Risk and Atherosclerosis J. Clin. Endocrinol. Metab., June 1, 2006; 91(6): 2191 - 2200. [Abstract] [Full Text] [PDF]

				M. E. Molitch, D. R. Clemmons, S. Malozowski, G. R. Merriam, S. M. Shalet, M. L. Vance, and for The Endocrine Society's Clinical Guidelines Su Evaluation and Treatment of Adult Growth Hormone Deficiency: An Endocrine Society Clinical Practice Guideline J. Clin. Endocrinol. Metab., May 1, 2006; 91(5): 1621 - 1634. [Abstract] [Full Text] [PDF]

				J. Bollerslev, T. Ueland, A. P Jorgensen, K. J Fougner, R. Wergeland, T. Schreiner, and P. Burman Positive effects of a physiological dose of GH on markers of atherogenesis: a placebo-controlled study in patients with adult-onset GH deficiency. Eur. J. Endocrinol., April 1, 2006; 154(4): 537 - 543. [Abstract] [Full Text] [PDF]

				E. R Christ, M. H Cummings, M. Stolinski, N. Jackson, P. J Lumb, A. S Wierzbicki, P. H Sonksen, D. L Russell-Jones, and A M. Umpleby Low-density lipoprotein apolipoprotein B100 turnover in hypopituitary patients with GH deficiency: a stable isotope study. Eur. J. Endocrinol., March 1, 2006; 154(3): 459 - 466. [Abstract] [Full Text] [PDF]

				J. Bollerslev, J. Hallen, K. J Fougner, A. P. Jorgensen, C. Kristo, H. Fagertun, O. Gudmundsen, P. Burman, and T. Schreiner Low-dose GH improves exercise capacity in adults with GH deficiency: effects of a 22-month placebo-controlled, crossover trial Eur. J. Endocrinol., September 1, 2005; 153(3): 379 - 387. [Abstract] [Full Text] [PDF]

				A. Colao, C. Di Somma, A. Cuocolo, L. Spinelli, W. Acampa, S. Spiezia, F. Rota, M. C. Savanelli, and G. Lombardi Does a Gender-Related Effect of Growth Hormone (GH) Replacement Exist on Cardiovascular Risk Factors, Cardiac Morphology, and Performance and Atherosclerosis? Results of a Two-Year Open, Prospective Study in Young Adult Men and Women with Severe GH Deficiency J. Clin. Endocrinol. Metab., September 1, 2005; 90(9): 5146 - 5155. [Abstract] [Full Text] [PDF]

				R. Lanes, A. Soros, K. Flores, P. Gunczler, E. Carrillo, and J. Bandel Endothelial Function, Carotid Artery Intima-Media Thickness, Epicardial Adipose Tissue, and Left Ventricular Mass and Function in Growth Hormone-Deficient Adolescents: Apparent Effects of Growth Hormone Treatment on These Parameters J. Clin. Endocrinol. Metab., July 1, 2005; 90(7): 3978 - 3982. [Abstract] [Full Text] [PDF]

				A. Colao, C. Di Somma, F. Rota, S. Di Maio, M. Salerno, A. Klain, S. Spiezia, and G. Lombardi Common Carotid Intima-Media Thickness in Growth Hormone (GH)-Deficient Adolescents: A Prospective Study after GH Withdrawal and Restarting GH Replacement J. Clin. Endocrinol. Metab., May 1, 2005; 90(5): 2659 - 2665. [Abstract] [Full Text] [PDF]

				A. Colao, C. Di Somma, F. Rota, R. Pivonello, M. C. Savanelli, S. Spiezia, and G. Lombardi Short-Term Effects of Growth Hormone (GH) Treatment or Deprivation on Cardiovascular Risk Parameters and Intima-Media Thickness at Carotid Arteries in Patients with Severe GH Deficiency J. Clin. Endocrinol. Metab., April 1, 2005; 90(4): 2056 - 2062. [Abstract] [Full Text] [PDF]

				M. Gola, S. Bonadonna, M. Doga, and A. Giustina Growth Hormone and Cardiovascular Risk Factors J. Clin. Endocrinol. Metab., March 1, 2005; 90(3): 1864 - 1870. [Abstract] [Full Text] [PDF]

				S.-i. Kawachi, N. Takeda, A. Sasaki, Y. Kokubo, K. Takami, H. Sarui, M. Hayashi, N. Yamakita, and K. Yasuda Circulating Insulin-Like Growth Factor-1 and Insulin-Like Growth Factor Binding Protein-3 Are Associated With Early Carotid Atherosclerosis Arterioscler. Thromb. Vasc. Biol., March 1, 2005; 25(3): 617 - 621. [Abstract] [Full Text] [PDF]

				K. K. Miller, B. M. K. Biller, J. G. Lipman, G. Bradwin, N. Rifai, and A. Klibanski Truncal Adiposity, Relative Growth Hormone Deficiency, and Cardiovascular Risk J. Clin. Endocrinol. Metab., February 1, 2005; 90(2): 768 - 774. [Abstract] [Full Text] [PDF]

				F. Reis, M. V. Campos, M. Bastos, L. Almeida, M. Lourenco, C. A. Ferrer-Antunes, A. Palmeiro, J. D. Santos-Dias, J. F. Mesquita, M. Carvalheiro, et al. Platelet Hyperactivation in Maintained Growth Hormone-Deficient Childhood Patients after Therapy Withdrawal as a Putative Earlier Marker of Increased Cardiovascular Risk J. Clin. Endocrinol. Metab., January 1, 2005; 90(1): 98 - 105. [Abstract] [Full Text] [PDF]

				E. Conti, C. Carrozza, E. Capoluongo, M. Volpe, F. Crea, C. Zuppi, and F. Andreotti Insulin-Like Growth Factor-1 as a Vascular Protective Factor Circulation, October 12, 2004; 110(15): 2260 - 2265. [Full Text] [PDF]

				A. Tivesten, A. Barlind, K. Caidahl, N. Klintland, A. Cittadini, C. Ohlsson, and J. Isgaard Growth hormone-induced blood pressure decrease is associated with increased mRNA levels of the vascular smooth muscle KATP channel J. Endocrinol., October 1, 2004; 183(1): 195 - 202. [Abstract] [Full Text] [PDF]

				J. Svensson, B.-A. Bengtsson, T. Rosen, A. Oden, and G. Johannsson Malignant Disease and Cardiovascular Morbidity in Hypopituitary Adults with or without Growth Hormone Replacement Therapy J. Clin. Endocrinol. Metab., July 1, 2004; 89(7): 3306 - 3312. [Abstract] [Full Text] [PDF]

				H. S. Randeva, K. C. Lewandowski, J. Komorowski, R. D. Murray, C. J. O'Callaghan, E. W. Hillhouse, H. Stepien, and S. M. Shalet Growth Hormone Replacement Decreases Plasma Levels of Matrix Metalloproteinases (2 and 9) and Vascular Endothelial Growth Factor in Growth Hormone-Deficient Individuals Circulation, May 25, 2004; 109(20): 2405 - 2410. [Abstract] [Full Text] [PDF]