Serum Human Growth Hormone Research Articles

Human growth hormone, a marker for HIV infection among adult Igbo Nigerians: relationship between human growth hormone and CD4+ count with viral load.

Routine viral load and CD4+ testing is key to monitoring the extent of danger caused by HIV and response to antiretroviral therapy (ART) for HIV individuals, but its availability has been limited in low and middle-income countries. The study sort to ascertain relationship between serum Human Growth Hormone (HGH) gold standard with CD4 cells and viral load in HIV-infected patients. CD4+ T-cells, HIV viral load, and HGH were assayed in HIV- infected patients from May to December 2020. 460 subjects were engaged and separated into two groups: the HIV-infected untreated (Pre-ART) and the control groups. An interventional study was conducted for the Pre-Art group after six months. Serum HGH was assayed by the ELISA method, CD4 cell count was examined by BD-FACScan flow cytometer, and HIV viral load was assessed using RT-PCR. The CD4 count and serum HGH of Pre-ART HIV-infected subjects were significantly low (p<0.05), while the viral load was significantly high compared to those treated with ART for 6months (p<0.05). CD4 count and serum HGH were significantly higher (p<0.05) in females than in males. It also reveals that CD4 count correlates positively with HGH level (r= 0.191**). Serum HGH could serve as a surrogate marker and valuable index in monitoring HIV patients.

Mechanism for the Increase in Human Growth Hormone with Administration of a Novel Test Supplement and Results Indicating Improved Physical Fitness and Sleep Efficiency.

An oral test supplement increases serum human growth hormone (hGH) levels after acute administration in healthy adults. We investigated the mechanism for the increase in hGH and the effect of continued daily administration of the test supplement on measures of physical fitness and sleep efficiency. In Study 1, serum triiodothyronine (T3) was measured in samples from a prior placebo-controlled, double-blind study in which 16 healthy participants received both placebo and the test supplement in a crossover design; treatment order was randomized, and treatments were separated by a 1-week washout. In Study 2, physical fitness (VO2 max) was measured at baseline and after 2 weeks of daily administration of the test supplement (N = 12 healthy participants). Study 3 assessed daily sleep onset latency and time awake during 3 weeks of daily administration of the test supplement (N = 15 healthy participants). A fall from baseline in T3 was observed with placebo (-6.1 ± 8.5 ng/dL, P = .01). Of note, the change in T3 was smaller with the test supplement (-3.3 ± 10.7 ng/dL, P = not significant) but was not statistically different from placebo. Mean VO2 max increased by 6% from baseline after 2 weeks (P = .02). Sleep-onset latency and time awake during the night were reduced from baseline to week 3 by 22% and 65%, respectively (P = .01 and P = .02). The conservation of T3 levels suggests that the mechanism for increased hGH secretion by the test supplement is through somatostatin inhibition. Furthermore, pilot studies indicated that daily administration of the supplement improved physical fitness and sleep efficiency from baseline, effects consistent with increased endogenous hGH release. Clinical Trial Registration No. NCT02987868.

Prevalence of Sleep-Related Disordered Breathing among Acromegaly Patients and its Correlation to Cephalometric Parameters: An Indian Perspective

Introduction Sleep-related breathing disorders (SRBDs) including obstructive sleep apnea (OSA) and central sleep apnea (CSA) are quite common and are the leading causes of mortality in acromegaly. OSA in acromegaly is generally attributed to changes in oropharyngeal soft tissues. Data on OSA in Indian acromegaly are scant, especially cephalometric findings. The aim of this study is to evaluate the burden of SRBDs in acromegaly and its correlation to cephalometric parameters. Materials and Methods A total of 32 subjects (20 men and 12 women), diagnosed with acromegaly on the basis of standard clinical, biochemical, and hormonal measurements were recruited. In addition to the above parameters, polysomnography and magnetic resonance imaging (MRI) of the pharynx were performed in all subjects. Results The mean age of the subjects was 42.66 ± 11.13 years (range = 26–66) and mean duration of study after first presentation was 7.6 ± 6.3 years (range = 0.25–32). A total of 28 of 32 (93.3%) subjects had sellar MRI documented macroadenomas while 20 (62.5%) patients were treatment naive at the time of assessment. Twenty-nine (90.6%) patients had evidence of SRBD and all of them had OSA subtype. The Apnea–Hypopnea Index (AHI) indicating severity of OSA (mild 21.8%, moderate 34.4%, and severe 34.4%) correlated positively with tongue length, uvula length, and uvula thickness on MRI. However, AHI had no correlation with the severity of GH excess or disease activity or individual parameters such as weight, body mass index, blood pressure, hemoglobin A1c, serum human growth hormone, and insulin-like growth factor-1 level. Conclusion SRBD, the generally overlooked comorbidity, is highly prevalent in subjects with acromegaly and is almost always due to OSA, the severity of which correlates positively with tongue and uvula size. Well-designed, long-term follow-up study on a large cohort of acromegalic patients is required to improve our understanding on the subject.

Quantification of human growth hormone in human serum using isotope dilution-triple stage mass spectrometry

Quantification of human growth hormone in human serum using isotope dilution-triple stage mass spectrometry

Comparative Analysis of Human Growth Hormone in Serum Using SPRi, Nano-SPRi and ELISA Assays

Sensitive and selective methods for the detection of human growth hormone (hGH) over a wide range of concentrations (high levels of 50-100 ng ml−1 and minimum levels of 0.03 ng ml−1) in circulating blood are essential as variable levels may indicate altered physiology. For example, growth disorders occurring in childhood can be diagnosed by measuring levels of hGH in blood. Also, the misuse of recombinant hGH in sports not only poses an ethical issue it also presents serious health threats to the abuser. One popular strategy for measuring hGH misuse, relies on the detection of the ratio of 22 kDa hGH to total hGH, as non-22 kDa endogenous levels drop after exogenous recombinant hGH (rhGH) administration. Surface plasmon resonance imaging (SPRi) is an analytical tool that allows direct (label-free) monitoring and visualization of biomolecular interactions by recording changes of the refractive index adjacent to the sensor surface in real time. In contrast, the most frequently used colorimetric method, enzyme-linked immunosorbent assay (ELISA) uses enzyme labeled detection antibodies to indirectly measure analyte concentration after the addition of a substrate that induces a color change. To increase detection sensitivity, amplified SPRi uses a sandwich assay format and near infrared quantum dots (QDs) to increase signal strength. After direct SPRi detection of recombinant rhGH in spiked human serum, the SPRi signal is amplified by the sequential injection of detection antibody coated with near-infrared QDs (Nano-SPRi). In this study, the diagnostic potential of direct and amplified SPRi was assessed for measuring rhGH spiked in human serum and compared directly with the capabilities of a commercially available ELISA kit.

Engineering of a Pichia pastoris Expression System for High-Level Secretion of HSA/GH Fusion Protein

Human serum albumin (HSA) and human growth hormone (hGH) fusion protein [HSA/GH] is a promising long-acting form of GH to treat GH deficiency. This study attempted to engineer a P. pastoris strain for high-level production of HSA/GH to be used in basic research and clinical application. Strains contained two, three, and seven copies of HSA/GH gene were screened by selecting against Zeocin resistance. The results revealed that introducing two to three copies of HSA/GH gene was sufficient to give a significant increase in secretion level, compared with one copy of HSA/GH gene. No significant differences were observed between two to three copies and seven copies. Co-expression with either one copy of exogenous ERO1 or PDI in a strain carrying multicopies of HSA/GH gene led to varying degrees of increase in HSA/GH secretion. The effect of introducing multicopies of PDI was similar to that of one copy of PDI, but introducing excess copies of ERO1 reduced HSA/GH secretion. Simultaneous co-expression with PDI and ERO1 was less effect than either PDI co-expression or ERO1 co-expression. A strain showing higher secretion level was successfully applied to large-scale fermentation with the productivity of 3-4 g/l.

High sensitivity mass spectrometric quantification of serum growth hormone by amphiphilic peptide conjugation

Amphiphilic peptide conjugation affords a significant increase in sensitivity with protein quantification by electrospray-ionization mass spectrometry. This has been demonstrated for human growth hormone (GH) in serum using N-(3-iodopropyl)-N,N,N-dimethyloctylammonium iodide as derivatizing reagent. The signal enhancement achieved is up to a factor of 5-6 and enables extension of the applicable concentration range down to the very low concentrations (≤ 1.0 µg/L) as encountered with clinical glucose suppression tests for patients with acromegaly. The method has been validated using a set of serum samples spiked with known amounts of recombinant 22 kDa GH in the range of 0.48 to 7.65 µg/L. The coefficient of variation (CV) calculated based on the deviation of results from the expected concentrations was 3.5%. The limit of detection (LoD) was determined as 0.1 µg/L and the limit of quantification (LoQ) as 0.4 µg/L. The potential of the method as a tool in clinical practice has been demonstrated with patient samples of about 1 µg/L.

Maternal Serum Human Placental Growth Hormone (hPGH) at 11 to 13 Weeks of Gestation in Preeclampsia

Objective. Human placental growth hormone (hPGH) is produced by human placenta and plays a central role in the maternal metabolic adjustments to pregnancy. The objective of this study was to investigate the maternal serum concentration of hPGH at 11–13 weeks of gestation in pregnancies that subsequently developed preeclampsia (PE), and to examine the possible association with uterine artery pulsatility index (PI) and maternal serum pregnancy-associated plasma protein-A (PAPP-A). Methods. The maternal serum concentration of hPGH at 11–13 weeks was measured in a case–control study from 60 cases that developed PE and 120 unaffected controls. The measured hPGH concentration was converted into a multiple of the expected median (MoM) in unaffected pregnancies. Regression analysis was used to determine the significance of association between hPGH MoM with uterine artery PI MoM and PAPP-A MoM. Results. In the pregnancies that subsequently developed PE the median serum hPGH concentration was not significantly different from that in the unaffected group (0.92 versus 1.00 MoM), whereas uterine artery PI was increased (1.31 versus 1.01 MoM) and serum PAPP-A was decreased (0.76 versus 1.01 MoM). In the group that developed PE there was no significant association between serum hPGH MoM and gestational age at delivery, uterine artery PI MoM, or serum PAPP-A MoM. Conclusion. The finding that in the PE group serum hPGH level during the first trimester is normal suggests that it is unlikely that this hormone plays a role in the pathogenesis of PE.

Single-File Diffusion of Protein Drugs through Cylindrical Nanochannels

A new drug delivery device using cylindrical block copolymer nanochannels was successfully developed for controlled protein drug delivery applications. Depending on the hydrodynamic diameter of the protein drugs, the pore size in cylindrical nanochannels could be controlled precisely down to 6 nm by Au deposition. Zero-order release of bovine serum albumin (BSA) and human growth hormone (hGH) by single-file diffusion, which has been observed for gas diffusion through zeolite pores, was realized up to 2 months without protein denaturation. Furthermore, a nearly constant in vivo release of hGH from the drug delivery nanodevice implanted to Sprague-Dawley (SD) rats was continued up to 3 weeks, demonstrating the feasibility for long-term controlled delivery of therapeutic protein drugs.

Maternal serum human placental growth hormone at 11 to 13 weeks in trisomy 21 and trisomy 18 pregnancies

To investigate the maternal serum concentration of human placental growth hormone (hPGH) in trisomy 21 and trisomy 18 pregnancies at 11 to 13 weeks of gestation and to examine the possible association between fetal nuchal translucency (NT) thickness and maternal serum free beta-human chorionic gonadotrophin (beta-hCG) and pregnancy-associated plasma protein-A (PAPP-A). The maternal serum concentration of hPGH at 11 to 13 weeks was measured in a case-control study from 28 pregnancies with fetal trisomy 21, 28 with trisomy 18 and 112 pregnancies with euploid fetuses. The median hPGH multiple of the median (MoM) in trisomy 21 and trisomy 18 pregnancies were compared with euploid pregnancies. Serum hPGH was significantly lower in trisomy 21 (0.93 MoM) and trisomy 18 (0.62 MoM) compared to euploid pregnancies (1.02 MoM). There was a significant association between serum hPGH and PAPP-A in both the euploid (r = 0.258, p = 0.006) and trisomy 21 pregnancies (r = 0.410, p = 0.030) but not in trisomy 18 pregnancies (p = 0.445). In the first trimester, serum hPGH in trisomy 21 and trisomy 18 pregnancies is reduced. This is the opposite of findings in previous studies reporting that in the second trimester, trisomy 21 and 18 pregnancies have increased hPGH.

Post-Eccentric Exercise Blunted hGH Response

The purpose of the present study was to test if a previous acute concentric exercise bout blunts hGH response after an eccentric exercise bout. Nine healthy untrained male university students (25.4+/-0.5 yr, 176.5+/-1.2 cm, and 79.4+/-2.0 kg) performed a concentric exercise bout followed by an eccentric exercise bout one week later. Serum human growth hormone (hGH), creatine kinase (CK), and lactate were measured before, immediately and up to 32 h after both exercise bouts. Higher lactate values were observed immediately, 5 and 10 min after the concentric bout (70%, 119%, and 142%, respectively, p<0.05) than the eccentric bout. There was a CK main time effect at 8 and 32 h after the exercise bouts compared to baseline values (p<0.002). However, peak serum CK effect size was higher after the concentric than the eccentric exercise bout, 1.3 and 0.9, respectively. hGH increased after both exercise bouts, however it reached significance only at immediately (207%), 5 min (256%), 10 min (276%), 20 min (300%), and 40 min (168%) after the concentric exercise bout (p<0.05). Our findings suggest that a previous concentric exercise bout may blunt the anabolic response expected after an eccentric exercise bout.

Fungal exposure endocrinopathy in sinusitis with growth hormone deficiency: Dennis-Robertson syndrome

A retrospective study was carried out on 79 patients with a history of mold exposure, fatigue, and chronic rhinosinusitis (CRS) to determine whether there is a causal relationship between fungal exposure and chronic sinusitis, fatigue, and anterior hypopituitarism, especially growth hormone deficiency (GHD). Of the patients, 94% had a history of CRS, endoscopically and/or computed tomography (CT) confirmed; 100% had chronic fatigue and 100% had either significant history of indoor mold exposure and/or positive mold plate testing as measured by settle plates, with an average colony count of 21 (0-4 normal). A total of 62 had positive mold plate testing and 17 had positive history of mold exposure. Of 75, 73 (97.3%) had positive serum immunoglobulin G (IgG)-specific antibodies to fungal antigens. Out of 8, 7 were positive for urinary trichothecenes. Resting levels of insulin-like growth factor 1 (IGF-1) averaged 123 ng/mL (range 43-285, normal 88-249 ng/mL). Despite normal resting levels of IGF-1, significant deficiency of serum human growth hormone (GH) was confirmed by insulin tolerance test (ITT) in 40 of 50 tested. In all, 51% (40/79) were GH deficient. Primary or secondary hypothyroidism in T3 and/or T4 was seen in 81% (64/79) patients; 75% (59/79) had adrenocorticotrophic hormone (ACTH) deficiency. Fungal exposure endocrinopathy likely represents the major cause of GHD, affecting approximately 4.8 million people compared to approximately known 60,000 cases from all other causes. A literature review indicates a possible mechanism of GHD in fungal exposure is that the fungal glucan receptors in the lenticulostellate cells of the anterior pituitary bind to fungal cells wall glucans and activate the innate immune system, which activates macrophages that destroy the fungus and lenticulostellate tissue. Treatment of patients included normal saline nasal irrigations, antifungal and antibiotic nasal sprays, appropriate use of oral antibiotics and antifungals, facial steamer with CitriDrops. Thymate and/or Intramax vitamin supplements, hormone replacement, and reduction of indoor mold levels. Resolution of rhinosinusitis was seen in 93% (41 of 45) of the patients who achieved a mold count by settling plates of 0-4 colonies. Thirty patients were unable to lower their mold counts below four colonies and had various degrees of mucosal disease and fatigue remaining. Fatigue was improved in all 37 patients who received GH and cortisol and/or thyroid hormone, which were deficient. Fatigue was partially relieved in 7 of the 37 who did not achieve mold counts of fewer than four colonies.

The First Blood Collection Attempt for Doping Control in an Olympic Tournament: Data on the Procedure Applied in Athens 2004 Olympic Games

The procedure for blood sampling in doping control, implemented for the first time as part of the official foren- sic testing programme in the Athens 2004 Summer Olympic Games is described. 743 whole blood and serum samples from 37 sports were analyzed. In serum human growth hormone and hemoglobin based oxygen carriers were screened for. In whole blood samples heterologous blood transfusion was detected. Routine haematological parameters (hematocrit, haemoglobin) were followed in a very limited range only in Modern Pentathlon under the responsibility of the respective International Federation. The majority of the blood samples collected concerned events in athletics. Endurance sports accounted for 81% of the whole blood sampling. Athletics, swimming and rowing represented 55% of the serum samples analyzed. Extension of testing for oxygen transport enhancing agents in anaerobic sports should be seriously considered by future organizers and the International Olympic Committee. The mean time for an athlete to report to the Doping Control Station for blood collection was 6.1 hours; 27% of the ath- letes tested (from 19 sports) failed to appear within the 12-hours time limit set. Training of the phlebotomists was proven effective. Only 25 athletes of those tested (3%) reported to have felt uncomfort- able. The majority of complaints (47%) concerned the prolonged waiting period and the long blood collection time (48%). Finally, an earlier agreement between all involved parties, attempts to decrease the time to appear at the site of blood col- lection and shortening of the duration of blood collection and sealing of the samples are recommended.

Phase I Dose Escalation Study of the Anti–Insulin-Like Growth Factor-I Receptor Monoclonal Antibody CP-751,871 in Patients with Refractory Solid Tumors

This phase I study was undertaken to define the maximum tolerated dose, safety, and pharmacokinetic profile of CP-751,871. Using a rapid dose escalation design, patients with advanced nonhematologic malignancies were treated with CP-751,871 in four dose escalation cohorts. CP-751,871 was administered i.v. on day 1 of each 21-day cycle. Pharmacokinetic evaluation was done in all treatment cohorts during cycles 1 and 4. Twenty-four patients received 110 cycles at four dose levels. The maximum tolerated dose exceeded the maximal feasible dose of 20 mg/kg and, thus, was not identified. Treatment-related toxicities were generally mild. The most common adverse events were hyperglycemia, anorexia, nausea, elevated aspartate aminotransferase, elevated gamma-glutamyltransferase, diarrhea, hyperuracemia, and fatigue. At 20 mg/kg, 10 of 15 patients experienced stability of disease. Two of these patients experienced long-term stability. There were no objective responses. Pharmacokinetic analysis revealed a dose-dependent increase in CP-751,871 exposure and approximately 2-fold accumulation on repeated dosing in 21-day cycles. Plasma concentrations of CP-751,871 attained were several log-fold greater than the biologically active concentration. Treatment with CP-751,871 increased serum insulin and human growth hormone levels, with modest increases in serum glucose levels. CP-751,871 has a favorable safety profile and was well tolerated when given in continuous cycles. At the maximal feasible dose of 20 mg/kg, there was a moderate accumulation in plasma exposure, and most of the treated patients experienced stability of disease.

An overview of the doping control analysis during the Olympic Games of 2004 in Athens, Greece

This study summarizes the results obtained from the doping control analysis during the period of the XXVIII summer Olympic Games (30 July–29 August 2004). The analysis of all doping control samples was performed at the Doping Control Laboratory (DCL)—the World Anti-Doping Agency (WADA) Accredited Laboratory of Athens. Three thousand six hundred and seventeen tests were conducted in total throughout the games. In 23 specimens the presence of a prohibited substance was confirmed. Sixteen of those were related to anabolic agents. The screened results were confirmed with various mass spectrometry analytical techniques, such as gas chromatography/high resolution mass spectrometry (GC/HRMS), gas chromatography/mass spectrometry (GC/MS), gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS) and liquid chromatography/mass spectrometry (ion trap) (LC/MS). The results of the first time applied screening and confirmatory procedures for the detection of recombinant human growth hormone in serum were also presented. Besides, 107 therapeutic use exemptions (TUE) were verified for glucocorticosteroid and beta2-agonist use.

Metabolic and Hormonal Changes of Severely Burned Children Receiving Long-Term Oxandrolone Treatment

When given to children for 1 year after a severe burn, oxandrolone significantly improves lean body mass, bone mineral content, and muscle strength. The beneficial effects of oxandrolone on height and weight were observed 1 year after treatment was discontinued. To study the efficacy of oxandrolone in severely burned children for 12 months after burn and 12 months after the drug was discontinued. Oxandrolone attenuates body catabolism during the acute phase after burn. It is unclear whether oxandrolone would have any beneficial effects during long-term treatment or if there were any effects after the drug was stopped. Sixty-one children with 40% total body surface area burns were enrolled in this study. Patients were randomized into those to receive oxandrolone (n = 30) or placebo (n = 31) for the first 12 months. Treatment was discontinued after 12 months, and the patients were studied without the drug for the following 12 months. At discharge and 6, 12, 18, and 24 months after burn, height, weight, body composition, resting energy expenditure, muscle strength, and serum human growth hormone, insulin-like growth factor-I (IGF-1), IGF binding protein-3, insulin, cortisol, parathyroid hormone, tri-iodothyronine uptake (T3 uptake), and free thyroxine index (FTI) were measured. Statistical analysis used Tukey multiple comparison test. Significance was accepted at P < 0.05. Oxandrolone improved lean body mass, bone mineral content and muscle strength compared with controls during treatment, P < 0.05. Serum IGF-1, T3 uptake, and FTI were significantly higher during drug treatment compared with controls, P < 0.05. Significant increases in height and weight with oxandrolone were observed after the end of treatment. Oxandrolone improved body composition and strength in severely burned children during the 12 months of treatment. Its effect on height and weight continued after treatment was discontinued.

Growth hormone: its measurement and the need for assay harmonization.

Serum human growth hormone (hGH) assays show a wide range in bias and in cut-off values for provocative tests, which vary from 13.5 to 35-40 mU/L when they have been established. Studies using novel hGH assays show that methods that are absolutely specific for 22-kDa hGH may not identify bioactive hGH peaks and that 20:22-kDa hGH ratios are increased in acromegaly. Greater harmonization of serum hGH methods can be achieved by: changing from IS 80/505 to IS 98/574, which is calibrated in mass units of recombinant 22-kDa hGH; using monoclonal/polyclonal or polyclonal/polyclonal antibody combinations that measure both 20-kDa and 22-kDa hGH; the development of assays such as the immunofunctional hGH assay which has the convenience of an immunometric assay but gives results that correlate better with bioassays collaboration between manufacturers and laboratories to establish method-related cut-off limits for provocative tests of hGH status.

Synthesis, characterization and protein adsorption behaviors of PLGA/PEG di-block co-polymer blend films

A series of poly( d,l-lactic-co-glycolic acid) (PLGA)/poly(ethyleneglycol) (PEG) di-block copolymers were synthesized by ring-opening polymerization of d,l-lactide and glycolide with different molecular weights of monomethoxy polyethyleneglycol (mPEG) 750, 2000 and 5000 as an initiator. The bulk properties of these co-polymers were characterized by using 1H NMR spectroscopy, gel permeation chromatography, differential scanning calorimetry (DSC). Electron spectroscopy for chemical analysis (ESCA) results, in which the blend films with the di-block copolymers showed increasing surface oxygen atomic percentage with increasing PEG chain length, indicate that PEG chain segment in the di-block copolymers is surface oriented and enriched onto the surface of the blend films. The extent of protein adsorption onto the surface of these blend films was studied, using iodine radio-labeled human serum albumin, gamma globulin and human growth hormone. The protein adsorption amount was reduced for the blend films prepared with PLGA/PEG 750 and 2000 di-block copolymers, but increased to a great extent for PLGA/PEG 5000 di-block copolymer. This is due to the increased water uptake capacity of the blend film, which absorbed more protein molecules into a swollen polymer matrix in addition to surface adsorption.

Suppression of immunological response against a transgene product delivered from microencapsulated cells.

A potential obstacle to successful gene therapy for some patients is the in vivo production of neutralizing antibodies against the recombinant therapeutic product delivered. To mimic this clinical situation, we implanted microencapsulated recombinant cells producing human growth hormone into C57B1/6 mice to provoke antihuman growth hormone antibody production. We then investigated the efficacy of different immunosuppressive treatments to inhibit the development of neutralizing antibodies. The experimental mice were treated with either an immunosuppressive drug (FK506 or cyclophosphamide), a cytokine (interferon-gamma [IFN-gamma] or interleukin-12 [IL-12], or a monoclonal antibody (anti-CD4, anti-gp39, or CTLA4-Ig). Serum human growth hormone and mouse anti-human growth hormone antibody levels were measured by enzyme-linked immunosorbent assay (ELISA) for 4 weeks. There were three patterns of response noted among the seven treatment groups. First, the mice receiving IFN-gamma, IL-12, anti-gp39, or CTLA4-Ig were similar to the untreated controls-no suppression of anti-hGH antibodies and no improvement in delivery of hGH. Next, the mice receiving FK506 or cyclosphosphamide showed > or = 90% suppression of antibodies but also no improvement in product delivery. Last, the mice receiving anti-CD4 showed almost complete antibody suppression over 1 month postimplantation. Furthermore, only anti-CD4 permitted a sustained level of human growth hormone delivery to day 28, in contrast to the controls whose human growth hormone delivery was undetectable by day 14 postimplantation. Hence, the use of anti-CD4 inhibited formation of neutralizing antibodies against a recombinant gene product delivered in vivo, and allowed prolonged delivery of a foreign protein. Its role as adjunct treatment for appropriate patients receiving gene therapy should be examined further.

Testosterone, Growth Hormone and IGF-I Responses to Acute and Chronic Resistive Exercise in Men Aged 55-70 Years

We investigated the responses of serum testosterone (T) and human growth hormone (hGH) concentrations to a bout of heavy resistive exercise and the responses of T, hGH, and insulin-like growth factor I (IGF-I) to a 16 wk progressive resistive training program in 13 men (60 +/- 4 yrs). Body composition via hydrostatic weighing and muscle strength using a 3 repetition maximum (3RM) test on 6 variable resistance exercise machines were assessed before and after the training program. Fasting blood samples were drawn on 2 consecutive days prior to training and again on 2 consecutive days after the last day of exercise. Blood was also drawn immediately before and approximately 10 min after a single exercise session during the first wk of training, and after an exercise session of the same relative resistance during the last wk of training. The training program resulted in a 37% increase in upper body strength and a 39% increase in lower body strength (both p < 0.01). Lean body mass increased significantly (61.8 +/- 2.1 vs 63.7 +/- 7.8 kg; p < 0.001) while % fat decreased (26.5 +/- 1.5 vs 24.9 +/- 6.0%; p < 0.01) as a result of training. Serum T concentration was unchanged, but GH increased approximately 18-fold in response to a single bout of resistive exercise before (0.24 +/- 0.08 vs 4.60 +/- 1.35 mg/l) and after (0.26 +/- 0.06 vs 4.66 +/- 1.46 mg/l; p < 0.01) training. Baseline serum concentrations of T, hGH, and IGF-I were unaffected by the training program. We conclude that an acute bout of resistive exercise causes a substantial hGH response in older men, but 16 wks of progressive resistive training does not affect baseline concentrations of the anabolic hormones.