Adipose tissue triglyceride turnover, de novo lipogenesis, and cell proliferation in humans measured with 2H2O

The turnover of adipose tissue components (lipids and cells) and the pathways of adipose lipid deposition have been difficult to measure in humans. We apply here a (2)H(2)O long-term labeling technique for concurrent measurement of adipose-triglyceride (TG) turnover, cell (DNA) proliferation, and de novo lipogenesis (DNL). Healthy subjects drank (2)H(2)O (70 ml/day) for 5-9 wk. Subcutaneous adipose tissue aspirates were taken (gluteal, thigh, and flank depots). Deuterium incorporation into TG glycerol (representing all-source TG synthesis), TG palmitate (representing DNL, by mass isotopomer distribution analysis), and DNA (representing cell proliferation) was measured by gas chromatography-mass spectrometry. Subjects tolerated the protocol well, and body (2)H(2)O enrichments were stable. Mean TG-glycerol fractional synthesis was 0.12 (i.e., 12%) with a range of 0.03-0.32 after 5 wk and 0.20 (range 0.08-0.49) after 9 wk (TG half-life 200-270 days). Label decay measurements 5-8 mo after discontinuing (2)H(2)O gave similar turnover estimates. Net lipolysis (TG turnover) was 50-60 g/day. DNL contribution to adipose-TG was 0.04 after 9 wk, representing approximately 20% of newly deposited TG. Cell proliferation was 0.10-0.17 after 9 wk (half-life 240-425 days). In summary, long-term (2)H(2)O administration to human subjects allows measurement of the dynamics of adipose tissue components. Turnover of all elements is slow, and DNL contributes approximately 20% of new TG.

Measurement in vivo of proliferation rates of slow turnover cells by 2H2O labeling of the deoxyribose moiety of DNA

We describe here a method for measuring DNA replication and, thus, cell proliferation in slow turnover cells that is suitable for use in humans. The technique is based on the incorporation of (2)H(2)O into the deoxyribose (dR) moiety of purine deoxyribonucleotides in dividing cells. For initial validation, rodents were administered 4% (2)H(2)O in drinking water. The proliferation rate of mammary epithelial cells in mice was 2.9% per day and increased 5-fold during pregnancy. Administration of estradiol pellets (0-200 microg) to ovariectomized rats increased mammary epithelial cell proliferation, according to a dose-response relationship up to the 100 microg dose. Similarly, proliferation of colon epithelial cells was stimulated in a dose-response manner by dietary cholic acid in rats. Bromodeoxyuridine labeling correlated with the (2)H(2)O results. Proliferation of slow turnover cells was then measured. Vascular smooth muscle cells isolated from mouse aorta divided with a half-life in the range of 270-400 days and die-away values after (2)H(2)O wash-out confirmed these slow turnover rates. The proliferation rate of an adipocyte-enriched fraction from mouse adipose tissue depots was 1-1.5% new cells per day, whereas obese ad libitum-fed obob mice exhibited markedly higher fractional and absolute proliferation rates. In humans, stable long-term (2)H(2)O enrichments in body water were achieved by daily (2)H(2)O intake, without toxicities. Labeled dR from fully turned-over blood cells (monocytes or granulocytes) exhibited a consistent amplification factor relative to body (2)H(2)O enrichment ( approximately 3.5-fold). The fraction of newly divided naive-phenotype T cells after 9 weeks of labeling with (2)H(2)O was 0.056 (CD4(+)) and 0.043 (CD8(+)) (replacement rate <0.1% per day). In summary, (2)H(2)O labeling of dR in DNA allows safe, convenient, reproducible, and inexpensive measurement of cell proliferation in humans and experimental animals and is well suited for slow turnover cells.

Resistance exercise and supraphysiologic androgen therapy in eugonadal men with HIV-related weight loss: a randomized controlled trial

CONTEXT

Repletion of lean body mass (LBM) that patients lose in human immunodeficiency virus (HIV) infection has proved difficult. In healthy, HIV-seronegative men, synergy between progressive resistance exercise (PRE) and very high-dose testosterone therapy has been reported for gains in LBM and muscle strength.

OBJECTIVE

To determine whether a moderately supraphysiologic androgen regimen, including an anabolic steroid, would improve LBM and strength gains of PRE in HIV-infected men with prior weight loss and whether protease inhibitor antiretroviral therapy prevents lean tissue anabolism.

DESIGN

Double-blind, randomized, placebo-controlled trial; post hoc analysis for effect of HIV-protease inhibitor therapy conducted from January to October 1997.

SETTING

Referral center in San Francisco, Calif.

PATIENTS

Volunteer sample of 24 eugonadal men with HIV-associated weight loss (mean, 9% body weight loss), recruited from an AIDS clinic and by referral and by advertisement.

INTERVENTION

For 8 weeks, all subjects received supervised PRE with physiologic intramuscular testosterone replacement (100 mg/wk) to suppress endogenous testosterone production. Randomization was between an anabolic steroid, oxandrolone, 20 mg/d, and placebo.

MAIN OUTCOME MEASURES

Lean body mass, nitrogen balance (10-day metabolic ward measurements), body weight, muscle strength, and androgen status.

RESULTS

Twenty-two subjects completed the study (1 1 per group). Both groups showed significant nitrogen retention and increases in LBM, weight, and strength. The mean (SD) gains were significantly greater in the oxandrolone group than in the placebo group (5.6 [2.1] vs 3.8 [1.8] g of nitrogen per day [P=.05]; 6.9 [1.7] vs 3.8 [2.9] kg of LBM [P=.005]; greater strength gains for various upper and lower body muscle groups by maximum weight lifted [P = .02-.05] and dynamometry [P = .01 -.05]). The mean (SD) high-density lipoprotein cholesterol level declined 0.25 (0.14) mmol/L (9.8 [5.4] mg/dL) significantly in the oxandrolone group (P < .001 compared with placebo). Results were similar whether or not patients were taking protease inhibitors. One subject in the oxandrolone group discontinued the study because of elevated liver function test results.

CONCLUSIONS

A moderately supraphysiologic androgen regimen that included an anabolic steroid, oxandrolone, substantially increased the lean tissue accrual and strength gains from PRE, compared with physiologic testosterone replacement alone, in eugonadal men with HIV-associated weight loss. Protease inhibitors did not prevent lean tissue anabolism.

Monitoring changes in fat-free mass in HIV-positive men with hypotestosteronemia and AIDS wasting syndrome treated with gonadal hormone replacement therapy

OBJECTIVE

To compare methods for assessing changes in body composition during gonadal hormone replacement therapy in a group of HIV-positive men with AIDS wasting syndrome.

DESIGN

The study included a 21-day, double-blind, randomized, placebo-controlled inpatient intervention and a 12-week open-label intervention. The inpatient intervention included 18 men who were confined to a metabolic ward. Days 1-7 comprised weight stabilization and body composition measures followed by 14 days of nandrolone decanoate at either 65 or 195 mg weekly, or placebo, and repeat testing. The open-label intervention comprised 12 weeks of 200 mg nandrolone decanoate fortnightly with measurements of fat-free mass at 6 and 12 weeks.

METHODS

The inpatient intervention measured nitrogen balance from 24 h urine and fecal collections and fat-free mass by dual energy x-ray absorptiometry (DEXA), bioimpedance spectroscopy (BIS) and D2O dilution. Nitrogen balance was calculated as the difference between dietary intake and urinary and fecal nitrogen excretion. Nitrogen was converted to fat-free mass using the constant of 32.5 g. Repeated measures analysis of variance was used to determine which methods were significantly different from the reference nitrogen balance technique.

RESULTS

Nitrogen accretion of lean tissue was 0.55 and 0.85 kg weekly for low and high-dose groups, respectively. Estimated nitrogen retention during the open-label study was 0.42 kg weekly. Body weight increased with the estimated lean tissue accretion. DEXA, BIS and D2O methods demonstrated improvements in fat-free mass, although the BIS estimate of fat-free mass most closely matched the results of the nitrogen retention method.

CONCLUSION

DEXA, BIS and D2O techniques demonstrated increases in fat-free mass. The BIS method is less costly, more convenient to use, and had results that more closely matched those from nitrogen balance and retention methods. BIS may be the preferred method to monitor changes in fat-free mass in AIDS patients and patients with malnutrition.

Effects of nandrolone decanoate therapy in borderline hypogonadal men with HIV-associated weight loss

Serum testosterone concentrations are frequently in the low-normal range (lowest quartile, <500 ng/dl) in men with AIDS-wasting syndrome (AWS) and in other chronic wasting disorders. The response of patients in this group to androgen treatment has not been determined, however. Eighteen men with AWS (mean +/- standard error [SE]: 87% +/- 1% usual body weight; CD4 count 90 +/- 24) and borderline low serum testosterone concentrations (382 +/- 33 ng/dl) completed a 21-day placebo-controlled inpatient metabolic ward study comparing intramuscular (i.m.) placebo (n = 7) with low-dose (65 mg/week; n = 4) and high-dose (200 mg/week; n = 7) nandrolone decanoate, a testosterone analogue. Nitrogen balance, stable isotope-mass spectrometric measurement of de novo lipogenesis (DNL), resting energy expenditure, and gonadal hormone levels were measured. Both low-dose and high-dose nandrolone resulted in significant nitrogen retention (33-52 g nitrogen/14 days, representing gains of 0.5 to 0.9 kg lean tissue/week) compared with placebo (loss of 11 g nitrogen/week). This was reflected biochemically in a borderline significant reduction of high DNL (p < .06). Serum testosterone and gonadotropins were suppressed whereas resting energy expenditure was unchanged by nandrolone treatment. In 10 study subjects completing a 12-week open-label follow-up phase, body weight increased by 4.9 +/- 1.2 kg, including 3.1 +/- 0.5 kg lean body mass, and treadmill exercise performance also improved. In summary, nandrolone decanoate therapy in the absence of an exercise program in borderline hypogonadal men with AWS caused substantial nitrogen retention compared with placebo, similar in extent to the nitrogen retention previously achieved with recombinant growth hormone. It is reasonable to expand the criteria for androgen treatment in AWS to include at least patients in the lowest quartile of serum testosterone.

Pharmacologic management of anorexia/cachexia

Anorexia is a symptom seen in the majority of patients with cancer or the acquired immunodeficiency syndrome (AIDS) who experience involuntary weight loss. It is frequently not seen as a symptom requiring management in the same proactive manner as pain, nausea, or constipation. Progressive inanition or wasting is a fundamental component of the complex phenomenon known as the anorexia/cachexia syndrome (ACS) of malignancy or AIDS. Weight loss can be seen in the full spectrum of patient care settings: as a presenting complaint, defining condition, treatment-related toxicity, or as a hallmark of impending death. Primary pharmacologic management of ACS includes use of orexigenic agents (appetite stimulants), anticatabolic agents (antimetabolic and anticytokine), and anabolic agents (primarily hormonal). In addition to these specific categories of pharmacologic intervention, broad aspects of symptom management need to be addressed and are complementary. The available literature evaluating pharmacologic management of ACS in both malignancy and AIDS is reviewed.

The etiology of wasting in the human immunodeficiency virus and acquired immunodeficiency syndrome

Wasting is a debilitating complication of the human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS) and is a major cause of morbidity and mortality. The etiology of wasting in HIV/AIDS is complex and its origins are multifactorial. Both patterns of simple starvation and the more complex metabolic and endocrine alterations associated with stress and trauma have been described in patients with the AIDS wasting syndrome. Observations suggest that the pathophysiology of the wasting in individual patients with HIV/AIDS may vary according to the primary cause of wasting and underlying disease activity. Optimal treatment of the AIDS wasting syndrome will depend on a thorough evaluation of all possible contributing factors. This review addresses the pathophysiologic basis of weight loss in HIV/AIDS, based on the current literature.