Subgingival Microbiota and Longitudinal Glucose Change: The Oral Infections, Glucose Intolerance and Insulin Resistance Study (ORIGINS).

Microbial communities along mucosal surfaces throughout the digestive tract are hypothesized as risk factors for impaired glucose regulation and the development of clinical cardiometabolic disease. We investigated whether baseline measures of subgingival microbiota predicted fasting plasma glucose (FPG) longitudinally. The Oral Infections, Glucose Intolerance and Insulin Resistance Study (ORIGINS) enrolled 230 diabetes-free adults (77% female) aged 20 to 55 y (mean ± SD, 34 ± 10 y) from whom baseline subgingival plaque and longitudinal FPG were measured. DNA was extracted from subgingival plaque, and V3 to V4 regions of the 16S rRNA gene were sequenced. FPG was measured at baseline and again at 2 y; glucose change was defined as follow-up minus baseline. Multivariable linear models regressed 2-y glucose change onto baseline measures of community diversity and abundances of 369 individual taxa. A microbial dysbiosis index (MDI) summarizing top individual taxa associated with glucose change was calculated and used in regression models. Models were adjusted for age, sex, race/ethnicity, education, smoking status, body mass index, and baseline glucose levels. Statistical significance was based on the false discovery rate (FDR; <0.05) or a Bonferroni-corrected P value of 1 × 10-4, derived from the initial 369 hypothesis tests for specific taxa. Mean 2-y FPG change was 1.5 ± 8 mg/dL. Baseline levels of 9 taxa predicted FPG change (all FDR <0.05), among which Stomatobaculum sp oral taxon 097 and Atopobium spp predicted greater FPG change, while Leptotrichia sp oral taxon 498 predicted lesser FPG change (all 3 P values, Bonferroni significant). The MDI explained 6% of variation in longitudinal glucose change (P < 0.001), and baseline glucose levels explained 10% of variation (P < 0.0001). FPG change values ± SE in the third versus first tertile of the MDI were 4.5 ± 0.9 versus 1.6 ± 0.9 (P < 1 × 10-4). Subgingival microbiota predict 2-y glucose change among diabetes-free men and women.

Proteasome inhibitors, including curcumin, improve pancreatic ß-cell function and insulin sensitivity in diabetic mice.

BACKGROUND: Type 2 diabetes stems from obesity-associated insulin resistance, and in the genetically susceptible, concomitant pancreatic ß-cell failure can occur, which further exacerbates hyperglycemia. Recent work by our group and others has shown that the natural polyphenol curcumin attenuates the development of insulin resistance and hyperglycemia in mouse models of hyperinsulinemic or compensated type 2 diabetes. Although several potential downstream molecular targets of curcumin exist, it is now recognized to be a direct inhibitor of proteasome activity. We now show that curcumin also prevents ß-cell failure in a mouse model of uncompensated obesity-related insulin resistance (Lepr(db/db) on the Kaliss background). RESULTS: In this instance, dietary supplementation with curcumin prevented hyperglycemia, increased insulin production and lean body mass, and prolonged lifespan. In addition, we show that short-term in vivo treatment with low dosages of two molecularly distinct proteasome inhibitors celastrol and epoxomicin reverse hyperglycemia in mice with ß-cell failure by increasing insulin production and insulin sensitivity. CONCLUSIONS: These studies suggest that proteasome inhibitors may prove useful for patients with diabetes by improving both ß-cell function and relieving insulin resistance.

Genetic association analysis of 30 genes related to obesity in a European American population.

OBJECTIVE: Obesity, which is frequently associated with diabetes, hypertension and cardiovascular diseases, is primarily the result of a net excess of caloric intake over energy expenditure. Human obesity is highly heritable, but the specific genes mediating susceptibility in non-syndromic obesity remain unclear. We tested candidate genes in pathways related to food intake and energy expenditure for association with body mass index (BMI). METHODS: We reanalyzed 355 common genetic variants of 30 candidate genes in seven molecular pathways related to obesity in 1982 unrelated European Americans from the New York Cancer Project. Data were analyzed by using a Bayesian hierarchical generalized linear model. The BMIs were log-transformed and then adjusted for covariates, including age, age(2), gender and diabetes status. The single-nucleotide polymorphisms (SNPs) were modeled as additive effects. RESULTS: With the stipulated adjustments, nine SNPs in eight genes were significantly associated with BMI: ghrelin (GHRL; rs35683), agouti-related peptide (AGRP; rs5030980), carboxypeptidase E (CPE; rs1946816 and rs4481204), glucagon-like peptide-1 receptor (GLP1R; rs2268641), serotonin receptors (HTR2A; rs912127), neuropeptide Y receptor (NPY5R;Y5R1c52), suppressor of cytokine signaling 3 (SOCS3; rs4969170) and signal transducer and activator of transcription 3 (STAT3; rs4796793). We also found a gender-by-SNP interaction (rs1745837 in HTR2A), which indicated that variants in the gene HTR2A had a stronger association with BMI in males. In addition, NPY1R was detected as having a significant gene effect even though none of the SNPs in this gene was significant. CONCLUSION: Variations in genes AGRP, CPE, GHRL, GLP1R, HTR2A, NPY1R, NPY5R, SOCS3 and STAT3 showed modest associations with BMI in European Americans. The pathways in which these genes participate regulate energy intake, and thus these associations are mechanistically plausible in this context.

Association of K121Q polymorphism in ENPP1 (PC-1) with BMI in Caucasian and African-American adults.

OBJECTIVE: To test for association of the ectonucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1) K121Q polymorphism with body mass index (BMI) and diabetes in a large sample of Caucasians and African-Americans by selectively genotyping individuals at the extremes of the phenotypic distribution. SUBJECTS: Subsets comprising the extremes of the BMI distribution (10th-20th and above the 90th BMI percentile for Caucasians and between the 10th-30th and above the 80th percentile for African-Americans) from a group of 10,260 Caucasian and 2268 African-American adults participating in New York Cancer Project were studied. METHODS: Subjects were genotyped for the ENPP1 K121Q polymorphism by pyrosequencing and tested for association with BMI and diabetes by regression analysis. RESULTS: Regression analysis with BMI as the dependent variable demonstrated a significant association (P = 0.02) of genotype at K121Q with BMI, with no significant race-by-genotype interaction (P = 0.30). Compared with Q/Q or Q/K individuals, the K/K individuals had a BMI approximately 1.3 kg/m2 higher, without effects of age, gender or race. By logistic regression analysis, the K121Q alleles had no significant effect on diabetes status (P = 0.37) in obese subjects. CONCLUSION: In both Caucasians and African-Americans, the K121 polymorphism in ENPP1 was associated with increased BMI, but not with diabetes.

Transgenic complementation of leptin-receptor deficiency. I. Rescue of the obesity/diabetes phenotype of LEPR-null mice expressing a LEPR-B transgene.

Mice homozygous for the Leprdb3J (db3J) mutation are null for all known isoforms of the leptin receptor (LEPR). These animals are obese, hyperphagic, cold intolerant, insulin resistant, and infertile. Mice homozygous for the Leprdb (db) mutation (lacking the B isoform only) have the same phenotype as db3J animals. To better understand the function(s) of the LEPR isoforms in vivo, we generated db3J/db3J and db/db mice bearing a transgene (neuron-specific enolase [NSE]-Rb) expressing the B isoform of LEPR, the isoform capable of activating the signal transducer and activator of transcription (STAT) pathway, under the control of the neuron-specific enolase enhancer/promoter. The NSE-Rb transgene was expressed in the brain, with low levels of expression in adrenals, testis, and white adipose tissue. LEPR-B transgene expression in NSE-Rb db3J/db3J mice partially corrected the increased fat mass, hyperphagia, and glucose intolerance while restoring fertility in males and rescuing the cold intolerance in both sexes. The body weights of NSE-Rb transgenic mice that possessed the full complement of short LEPR isoforms (NSE-Rb db/db mice) were similar to those of NSE-Rb db3J/db3J mice, suggesting that the short LEPR isoforms play little role in body weight regulation. Based on quantitative analysis of hypothalamic neuropeptide gene expression in the transgenic animals, we infer full restoration of leptin sensitivity to proopiomelanocortin (POMC) neurons, partial correction of leptin sensitivity in agouti gene-related protein (AGRP)/neuropeptide Y (NPY) neurons, and a lack of effect on leptin sensitivity of melanin concentrating hormone neurons. Thus, hypothalamic POMC and AGRP/NPY neurons are primary candidates as the mediators of the effects of the NSE-Rb transgene on energy homeostasis, ingestive behavior, the neuroendocrine system, and glucose metabolism.

Effects of exogenous gonadal steroids on leptin homeostasis in rats.

BACKGROUND: In humans, circulating concentrations of the hormone leptin, normalized to body fat mass, are significantly higher in females compared to males. This experiment was designed to determine whether the administration of exogenous androgen or estrogen would significantly alter the relationship between plasma leptin and fat mass in rats. METHODS: In the first experiment, plasma leptin and retroperitoneal and parametrial (female)/epididymal (male) adipose tissue expression of leptin mRNA were measured in five male and five female 9.5-week-old Sprague-Dawley rats. In a second experiment, gonadectomized 10.5-week-old female Sprague-Dawley rats received 1 or 2 weeks of daily intraperitoneal injections (in oil) of 750 mg testosterone propionate, 2.5 microg of estradiol benzoate or vehicle. At 0, 1, and 2 weeks, plasma concentrations of leptin, fat pad weight of parametrial and retroperitoneal fat pads, and leptin mRNA expression by Northern blot in retroperitoneal fat pads were determined. Daily weight and food intake of animals were monitored throughout the study. RESULTS: Circulating leptin concentrations per unit of fat pad mass and leptin mRNA expression normalized to actin mRNA were higher in gonadally intact female compared to male rats. Compared to placebo, estrogen administration decreased food intake and body weight, but had no significant effect on leptin mRNA expression or on circulating leptin concentration. Testosterone administration increased body weight and decreased expression of leptin mRNA (only after 2 weeks), but did not change food intake or circulating leptin concentration. CONCLUSIONS: Administration of estrogen did not affect either leptin expression or the circulating concentration of leptin. Administration of androgen decreased expression of leptin mRNA. However, even after 2 weeks of testosterone administration to gonadectomized females, plasma leptin concentration, corrected for fat pad weight, was higher in gonadectomized females than in intact males. Thus, sex steroid-associated changes in plasma leptin concentration and leptin mRNA expression are not sufficient to explain the observed sexual dimorphism in plasma leptin concentrations in rats.

An exploratory investigation of the morphology and biochemistry of cellulite.

Dimpling of the skin of the thighs and buttocks is commonly referred to as cellulite, and it afflicts women much more frequently than men. Whereas many therapies that presume cellulite is caused by an abnormality of adipose tissue have gained recent popularity, the basic pathophysiology of cellulite has not been clearly identified. Theoretically, cellulite could reflect differences in adipose tissue biochemistry or connective tissue structure of affected versus unaffected individuals and/or of affected versus unaffected regions within an individual. We report here on direct experimental examination of these possibilities. Seven healthy adult subjects (five women, two men; four affected, three unaffected) underwent sonography of the thigh, measurement of regional in vivo subcutaneous adipose tissue metabolism (catecholaminergic responsiveness and blood flow) by microdialysis probe studies of the abdomen and the thigh, and full-thickness wedge biopsy of the thigh under local anesthesia. The presence of cellulite was defined as evidence of dimpling of the skin of the posterolateral thigh when the subject stood with the affected leg flexed to 90 degrees at the hip and knee. Any continuous area of skin at least 3 cm in diameter in which no dimpling was evident was designated as "unaffected." In all affected individuals, studies were performed to include both affected and unaffected areas of the thigh. In vitro pathologic examination of wedge biopsies and in vivo sonographic examination of the thigh both showed a diffuse pattern of extrusion of underlying adipose tissue into the reticular dermis in affected, but not unaffected, individuals. In vitro and in vivo studies also demonstrated that women had a diffuse pattern of irregular and discontinuous connective tissue immediately below the dermis, but this same layer of connective tissue was smooth and continuous in men. This connective tissue layer was more irregular and discontinuous in affected versus unaffected individuals. No significant differences were noted in subcutaneous adipose tissue morphology, lipolytic responsiveness, or regional blood flow between affected and unaffected sites within individuals. There is a sexual dimorphism in the structural characteristics of subdermal connective tissue that predisposes women to develop the irregular extrusion of adipose tissue into the dermis, which characterizes cellulite. These gender-related differences are diffuse and not localized only to affected areas. There is no evidence of any primary role for adipose tissue physiology, blood flow, or biochemistry in the etiology of cellulite, although the connective tissue of the female thigh is structured to accentuate differences in small subdermal adipose tissue depots.

Concentrations of adipsin in blood and rates of adipsin secretion by adipose tissue in humans with normal, elevated and diminished adipose tissue mass.

Adipsin, which is identical to complement factor D, is synthesized by fat cells, circulates in the bloodstream and is profoundly deficient in mice with genetic and hypothalamic obesity. With the recent cloning of human adipsin, a quantitative human immunoassay has been developed. In the present study, we measured adipsin blood concentrations in humans with increased and decreased adipose stores as well as adipsin secretion by adipose tissue obtained from lean and obese individuals. The results demonstrate that adipsin is released by human adipose tissue fragments as has previously been shown in mice, and that, in contrast to obese mice, blood adipsin concentrations were not reduced in the obese humans tested in this study. We also observed that blood adipsin concentrations can vary as a function of feeding or adiposity, in that they tend to be mildly elevated in obese individuals or mildly reduced in individuals with total lipo-atrophy, cachexia related to AIDS and anorexia nervosa. Thus, the circulating concentration of adipsin tends to correlate positively with degree of adiposity. Clearly, no deficiency in blood adipsin concentrations or adipsin secretion by adipose tissue was observed in the obese individuals studied.

Utility of a C-jun microsatellite marker in determining gene dosage for fatty (fa).

The Zucker fatty (fa) mutation provides a genetic model for obesity and non-insulin dependent diabetes mellitus. The molecular pathogenesis of the metabolic phenotype of these animals is not known. Detailed molecular maps of the region surrounding the fa locus on rat chromosome 5 can be used for positional cloning experiments as well as to permit genotyping of animals from appropriate crosses before the confounding metabolic effects of obesity have occurred. We describe the development of a polymerase chain reaction (PCR) assay for a polymorphic simple sequence repeat (SSR) in the promoter region of the protooncogene c-Jun. This assay was used to position c-Jun 4.5cM proximal to the fa locus in 111 F2 progeny of a 13MBN fa/+ F1 intercross. Concurrent use of the c-Jun SSR with a previously described assay for a microsatellite in the glucose transporter, Glut1, permits rapid and accurate assessment of genotypes at the fa locus in animals of any age using minimal amounts of DNA. A strategy is described which minimizes the error rate in assigning genotype at the fatty locus for backcross and intercross progeny.

The little (lit) mutation cosegregates with the growth hormone releasing factor receptor on mouse chromosome 6.

The little (lit) autosomal recessive mutation in the mouse causes dwarfism due to isolated growth hormone deficiency. The in vitro physiology of pituitary growth hormone release in lit/lit animals suggests that an abnormality in the growth hormone releasing factor (GRF) receptor (Ghrfr) is a very likely candidate for the lit mutation. We mapped Ghrfr to the region around lit on Chromosome (Chr) 6 in 100 chromosomes of an FVB x Czech II interspecific backcross. Molecular markers were Neuropeptide Y (Npy), homeobox (Hoxa2), immunoglobulin kappa chain (Igk), wingless-related MMTV integration site (Wnt-2), cystic fibrosis (Cftr), carboxypeptidase A (Cpa), and Ghrfr. Map order and distances were as follows: Cen-II-Wnt-2-(0 cM)-Cftr-(6.0 cM)-Cpa-(8.0 cM)-Npy-(1.0 cM)-Hoxa2-(3.0 cM)-Ghrfr-(2.0 cM)-Igk. We mapped lit (by phenotype) relative to Hoxa2 and Igk on 72 F2 chromosomes of offspring of a B6CZ lit/ + x B6FVB lit/ + intercross and 18 chromosomes of offspring of a B6FVB lit/ + intercross. Map order and distances were as follows: Hoxa2-(2.1 cM)-lit/Ghrfr-(3.7 cM)-Igk. No recombinations between lit and Ghrfr were detected. Thus, Ghrfr maps to mouse Chr 6 and may be allelic with lit. Amplification of a short segment at the 3' end of the Ghrfr mRNA by reverse transcription coupled to the polymerase chain reaction showed a greatly diminished level of GRF receptor mRNA in the pituitaries of lit/lit mice as compared with lit/ + controls. Low level of message could reflect a primary molecular defect or be due to secondary hypoplasia of somatotropes.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of systemic growth hormone (GH) administration on regional adipose tissue in children with non-GH-deficient short stature.

Chronic administration of exogenous GH to GH-deficient children is associated with a selective depletion of the abdominal sc fat depot and a resultant relative increase in gluteal, relative to abdominal, adipocyte lipid content. In GH-deficient children, the degree of this change in relative lipid content per adipocyte appears to be correlated with decreases in sensitivity of abdominal subcutaneous fat to the antilipolytic action of insulin. We studied abdominal and gluteal sc adipose tissue from 10 children with short stature (height less than 5% ile, growth velocity less than 5 cm/yr, bone age delayed at least 2 yr), who were not GH deficient based upon provocative testing (non-GH-deficient short stature) 1) before beginning and 2) after 3 months of therapy with exogenous GH (Humatrope, 0.1 mg/kg sc 3 times/week). In abdominal and gluteal adipocytes, we measured lipid content, rates of reesterification of fatty acids released by ongoing lipolysis and rates of in vitro lipolysis and lipogenesis in response to insulin, adenosine, and various adrenoreceptor agonists. These biochemical measures were correlated with measures of statural growth and adipose tissue distribution in each subject. We found that GH therapy was associated with a significant reduction in abdominal adipocyte size (0.48 microgram +/- 0.08 lipid per cell prior to therapy vs. 0.43 microgram +/- 0.08 lipid per cell after therapy, P less than 0.05) and a significant increase in responsiveness of gluteal sc adipose tissue to the lipogenic actions of insulin. The significant correlations of changes in abdominal adipocyte volume with changes in regional adipose tissue insulin sensitivity that were noted in GH-deficient children were not noted in this subject population, perhaps due to effects of endogenous GH on pretreatment insulin responsiveness of adipose tissue. These data reaffirm that GH has site-specific effects on regional adipose tissue depots.

Regional differences in adrenoreceptor status of adipose tissue in adults and prepubertal children.

The relative anatomical distribution of adipose tissue in central (abdominal) vs. peripheral (extremity) depots is highly correlated with the risk of adiposity-related morbidities, such as hypertension, cardiovascular disease, and diabetes mellitus. In adults, comparisons of the functional status of plasma membrane adrenergic receptors indicate that abdominal adipocytes are more responsive to the lipolytic action of beta 1-adrenergic agonists, while gluteal adipocytes are more responsive to the antilipolytic action of alpha 2-adrenergic agonists. To determine whether such regional differences in adipocyte adrenoreceptor status are present before puberty, we obtained needle biopsy samples of abdominal and gluteal sc adipose tissue in the post-absorptive state from 13 prepubertal children and 47 adults of varying body compositions (obese vs. lean). Lipolysis rates were measured in the basal state and in the presence of 10(-7) M norepinephrine (a mixed alpha- and beta-adrenergic agonist) and 10(-7) M isoproterenol (a beta-adrenergic agonist). In children, there were no significant regional differences in either the basal rate of lipolysis or the responses to adrenergic lipolytic and antilipolytic stimuli. In lean and obese adults, gluteal sc adipose tissue was strikingly more responsive to antilipolytic alpha-adrenergic stimulation (P less than 0.0001) and less responsive to lipolytic beta-adrenergic stimuli (P less than 0.005) compared to abdominal tissue. Abdominal sc adipocytes from children had a significantly lower rate of basal lipolysis (P less than 0.01) and were more responsive to alpha 2-adrenergic (antilipolytic) stimuli (P less than 0.05) than abdominal adipocytes in adults. These results suggest that peripubertal endocrine changes may mediate the striking regional differences in adrenoreceptor status of adult adipose tissue, and that a decrease in the preponderance of alpha 2-receptors (antilipolytic) in abdominal adipose tissue may account in part for the relative loss of central vs. peripheral fat that occurs during puberty.

Effects of early pregnancy on regional adipose tissue metabolism.

Adipose tissue metabolism was studied in needle biopsies from femoral and abdominal subcutaneous depots, in 12 healthy young women, during early (9-11 weeks) pregnancy, and 6 weeks after a legal abortion. Both during pregnant and non-pregnant conditions, a higher lipoprotein lipase (LPL) activity was seen in the femoral compared to the abdominal region, but the LPL activity was not influenced by early pregnancy. Rates of fatty acid esterification and acylglyceride synthesis were not different between regions, nor affected by pregnancy. The stimulatory effect of norepinephrine (10(-7) M) on lipolysis was significantly greater in the abdominal than in the femoral region in both the pregnant and non-pregnant condition. This difference was apparently due to higher alpha-adrenergic activity in the femoral region. Pregnancy per se had no effect on lipolytic response to norepinephrine. These findings indicate that lipid accumulation is favoured in the femoral region in young women both during pregnant and non-pregnant conditions.

Lipolytic effects on diacylglycerol accumulation in human adipose tissue in vitro.

When fragments of rat or human adipose tissue, or isolated adipocytes, are incubated with [14C]glucose in vitro, [14C]diacylglycerol accumulates rapidly: it comprises 20-50% of newly synthesized (14C-labeled) acylglycerols, compared to less than 1% diacylglycerol accumulated in the bulk lipid store in vivo. The experiments reported in this study were performed to test the possibility that agents that influence the rate of lipolysis might differentially affect the accumulation of di- and triacylglycerol in human adipose tissue, and perhaps account for the discrepancy between the early labeling and the later accumulation of diacyglycerol. Fragments of gluteal subcutaneous adipose tissue obtained from obese men and women were incubated with isoproterenol, epinephrine plus yohimbine, adenosine deaminase, or dibutyryl 3',5'-cyclic adenosine monophosphate to stimulate lipolysis. Tissue fragments were also incubated with clonidine, adenosine, or insulin to inhibit lipolysis. No agent had any effect on the rate of accumulation of newly synthesized triacylglycerol. The effects of these agents on the rate of lipolysis were negatively correlated with their effects on accumulation of newly synthesized diacylglycerol. Newly synthesized diacylglycerol may be preferentially hydrolyzed by hormone sensitive lipase. This increased susceptibility to lipolytic stimulation, compared to newly synthesized triacylglycerol, may account for the minute accumulation of diacylglycerol in adipose tissue in vivo.

Regional changes in adrenergic receptor status during hypocaloric intake do not predict changes in adipocyte size or body shape.

The anatomic distribution of fat is related to the risk for obesity-associated morbidity. Among individuals with equal degrees of relative adiposity, those with an upper-body preponderance of fat distribution (android) have higher rates of diabetes, stroke, ischemic heart disease, and early death than those with preferential deposition of adipose tissue in lower portions of the body (hips, thighs, buttocks; gynecoid. There are well-documented anatomic site-related differences in the relative activities of the adrenergic receptors (beta 1----lipolysis; alpha 2----antilipolysis) that control lipolysis. We assessed modifications of the status of alpha 2- and beta 1-adrenergic receptor and subreceptor function in small fragments of adipose tissue obtained by needle biopsy from the gluteal and abdominal subcutaneous regions of five android, seven gynecoid, and six uniformly obese women during a period of weight maintenance (4 weeks) (T1), and after 15% weight loss on an 840 kcal/d diet (T2). Measurements of body shape and adipocyte size were made and related to changes in the metabolism of these adipocytes. The waist-to-hip ratio (WHR) was used to define these three types of regional distribution of fat in these obese subjects: android = WHR greater than 0.86; gynecoid = WHR less than or equal to 0.76; uniform = WHR greater than 0.76 less than or equal to 0.86. WHR was not significantly altered by weight loss in any of the three groups. Although significant effects of time and/or anatomic site on in vitro responses to isoproterenol, norepinephrine, clonidine, forskolin, and dibutyryl cAMP were found, these did not correlate with intra-individual changes in anthropometry or adipocyte size.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of systemic growth hormone (GH) administration on regional adipose tissue distribution and metabolism in GH-deficient children.

Chronic administration of exogenous GH to GH-deficient children is associated with a redistribution of adipose tissue from an abdominal (android) to a more peripheral (gynoid) distribution. We studied abdominal and gluteal sc adipose tissue from seven GH-deficient children 1) before beginning and 2) after 3 months of therapy with exogenous GH (0.1 mg/kg, sc, three times per week). In abdominal and gluteal adipocytes, we measured lipid content and rates of in vitro lipolysis and lipogenesis in response to insulin and various adrenoreceptor agonists. These results were correlated with measures of statural growth and adipose tissue distribution in each subject. We found that GH therapy was associated with a significant reduction in abdominal adipocyte size (0.68 +/- 0.09 micrograms lipid/cell before therapy vs. 0.49 +/- 0.07 after therapy; P less than 0.05), a significant reduction in overall basal rates of lipogenesis (0.43 +/- 0.06 mumol [14C]acylglyceride synthesized/10(6) cells.2 h before therapy vs. 0.27 +/- 0.09 after therapy), and with variable desensitization of abdominal sc adipose tissue to the antilipolytic effect of insulin. The extent of this decrease in insulin action was significantly correlated with changes in abdominal adipocyte lipid content (r = 0.77; P less than 0.05), and with the changes in the anatomical distribution of fat during the study period (r = 0.97; P less than 0.001), as measured by the relative lipid content per adipocyte at each site. We conclude that the site-specific changes in adipose distribution during GH administration are due in part to anatomical site-specific GH-mediated changes in insulin responsiveness of adipose tissue and that exogenous GH therapy is associated with a decrease in de novo triglyceride synthesis in GH-deficient children.

Recombinant growth hormone enhances muscle myosin heavy-chain mRNA accumulation and amino acid accrual in humans.

A potentially lethal complication of trauma, malignancy, and infection is a progressive erosion of muscle protein mass that is not readily reversed by nutritional support. Growth hormone is capable of improving total body nitrogen balance, but its role in myofibrillar protein synthesis in humans is unknown. The acute, in situ muscle protein response to an infusion of methionyl human growth hormone was investigated in the limbs of nutritionally depleted subjects during a period of intravenous refeeding. A 6-hr methionyl growth hormone infusion achieved steady-state serum levels comparable to normal physiologic peaks and was associated with a significant increase in limb amino acid uptake, without a change in body amino acid oxidation. Myosin heavy-chain mRNA levels, measured by quantitative dot blot hybridization, were also significantly elevated after growth hormone administration. The data indicate that methionyl growth hormone can induce intracellular amino acid accrual and increased levels of myofibrillar protein mRNA during hospitalized nutritional support and suggest growth hormone to be a potential therapy of lean body wasting.

Adrenergic control of adipocyte lipolysis in trauma and sepsis.

Adipocyte lipolysis and its adrenergic control were studied in vitro from normal patients and those with trauma and sepsis. The adrenergic receptors were studied in terms of their responsiveness, a measure of the postreceptor mechanism, and their sensitivity, a measure of the receptor number or affinity. With early trauma, beta-adrenergic responsiveness and receptor number were significantly decreased. This is desensitization of the beta-receptors with down regulation and indicates increased in vivo lipolysis in early injury. After 4 days these changes had returned to normal. Early sepsis resulted in a significant increase in beta- and alpha-receptor responsiveness with beta-upregulation. This indicated hypersensitivity of the adipocyte adrenergic receptors and suggests the presence of an in vivo block of the adrenergic receptors in early sepsis. This would decrease adipocyte lipolysis. After 4 days there was a decrease in beta-receptor responsiveness in the patients with sepsis, indicating that the adrenergic receptor block was no longer present and adipocyte adrenergic stimulated lipolysis was increased.

Iron deficiency and behavioral development in infants and preschool children.

This paper selectively reviews the main findings of studies on the possible effects of iron deficiency on cognitive function among infants and preschool children published after 1976, and presents data from a study recently conducted in rural Guatemala. In comparison to infants without signs of sideropenia, infants with iron deficiency with and without anemia tend to score lower in the Bayley Scale of Mental Development; conversely, there is no evidence for an association between iron deficiency and delayed motor development. Iron repletion therapy implemented over a period of 7 to 10 days is likely to result in an improvement in mental development scale scores among infants with iron deficiency with or without anemia. In comparison with preschool children without sideropenia, preschool children with iron deficiency with or without anemia are less likely to pay attention to relevant cues in problem solving situations.

A radioisotopic technique for analysis of free fatty acid reesterification in human adipose tissue.

Reesterification rates of free fatty acids (FFA) formed by intracellular triglyceride hydrolysis in small fragments of human adipose tissue were measured. Subcutaneous gluteal adipose tissue, obtained by needle biopsy, was incubated in a buffered albumin medium containing [3H]palmitate and [14C]glucose, each of high specific activity. In triglycerides (TG) and diglycerides (DG) synthesized by the tissue, [14C]glucose is incorporated exclusively into the glyceride-glycerol moiety, and 3H appears solely in the esterified fatty acids. Since rates of TG and DG synthesis can be determined from 14C accumulation rates in these molecules, the total amounts of FFA esterified can also be calculated. The difference between this estimate of total FFA esterification and the moles of [3H]palmitate esterified to these molecules represents the amount of unlabeled FFA from ongoing TG hydrolysis that was reesterified during the incubation. FFA recycling by the reesterification pathway is an important mechanism for the control of the quantity and proportions of FFA and glycerol leaving the human adipocyte. Fasting and beta-adrenergic stimulation reduce the fraction of endogenously released FFA that are reesterified from resting values of 30-40% to 8-21%, thereby increasing the molar ratio of FFA to glycerol leaving the adipocyte. The technique described can be employed to monitor sequential changes in this important metabolic cycle in humans under a wide range of nutritional and clinical circumstances.