Alternative type 2 diabetes screening tests may reduce the number of U.S. adults with undiagnosed diabetes.

AIM: To evaluate the U.S. population-level impact of two alternatives for initial type 2 diabetes screening [opportunistic random plasma glucose (RPG) > 6.7 mmol/l and a 1-h 50-g glucose challenge test (GCT) > 8.9 mmol/l] compared with American Diabetes Association (ADA)-recommended tests. METHODS: Using a sample (n = 1471) from the National Health and Nutrition Examination Survey (NHANES) 2013-2014 that represented 145 million U.S. adults at high risk for developing type 2 diabetes, we simulated a two-test screening process. We compared ADA-recommended screening tests [fasting plasma glucose (FPG), 2-h 75-g oral glucose tolerance test (OGTT), HbA1c ] vs. initial screening with opportunistic RPG or GCT (followed by FPG, OGTT or HbA1c ). After simulation, participants were entered into an individual-level Monte Carlo-based Markov lifetime outcomes model. Primary outcomes were representative number of U.S. adults correctly identified with type 2 diabetes, societal lifetime costs and quality-adjusted life years (QALYs). RESULTS: In NHANES 2013-2014, 100 individuals had undiagnosed diabetes [weighted estimate: 8.4 million, standard error (se): 1.1 million]. Among ADA-recommended screening tests, FPG followed by OGTT (FPG-OGTT) was most sensitive, identifying 35 individuals with undiagnosed diabetes (weighted estimate: 3.2 million, se: 0.9 million). Four alternative screening strategies performed superior to FPG-OGTT, with RPG followed by OGTT being the most sensitive overall, identifying 72 individuals with undiagnosed diabetes (weighted estimate: 6.1 million, se: 1.0 million). There was no increase in average lifetime costs and comparable QALYs. CONCLUSIONS: Initial screening using opportunistic RPG or a GCT may identify more U.S. adults with type 2 diabetes without increasing societal costs.

Glucose challenge test screening for prediabetes and early diabetes.

AIMS: To test the hypothesis that a 50-g oral glucose challenge test with 1-h glucose measurement would have superior performance compared with other opportunistic screening methods. METHODS: In this prospective study in a Veterans Health Administration primary care clinic, the following test performances, measured by area under receiver-operating characteristic curves, were compared: 50-g oral glucose challenge test; random glucose; and HbA1c level, using a 75-g oral glucose tolerance test as the 'gold standard'. RESULTS: The study population was comprised of 1535 people (mean age 56 years, BMI 30.3 kg/m2 , 94% men, 74% black). By oral glucose tolerance test criteria, diabetes was present in 10% and high-risk prediabetes was present in 22% of participants. The plasma glucose challenge test provided area under receiver-operating characteristic curves of 0.85 (95% CI 0.78-0.91) to detect diabetes and 0.76 (95% CI 0.72-0.80) to detect high-risk dysglycaemia (diabetes or high-risk prediabetes), while area under receiver-operating characteristic curves for the capillary glucose challenge test were 0.82 (95% CI 0.75-0.89) and 0.73 (95% CI 0.69-0.77) for diabetes and high-risk dysglycaemia, respectively. Random glucose performed less well [plasma: 0.76 (95% CI 0.69-0.82) and 0.66 (95% CI 0.62-0.71), respectively; capillary: 0.72 (95% CI 0.65-0.80) and 0.64 (95% CI 0.59-0.68), respectively], and HbA1c performed even less well [0.67 (95% CI 0.57-0.76) and 0.63 (95% CI 0.58-0.68), respectively]. The cost of identifying one case of high-risk dysglycaemia with a plasma glucose challenge test would be $42 from a Veterans Health Administration perspective, and $55 from a US Medicare perspective. CONCLUSIONS: Glucose challenge test screening, followed, if abnormal, by an oral glucose tolerance test, would be convenient and more accurate than other opportunistic tests. Use of glucose challenge test screening could improve management by permitting earlier therapy.

Disposition index identifies defective beta-cell function in cystic fibrosis subjects with normal glucose tolerance.

BACKGROUND: In non-cystic fibrosis (CF) subjects, the disposition index (DI) is a strong predictor of the development of type 2 diabetes. CF subjects are at high risk of diabetes. We hypothesized that DI would be reduced in CF patients with normal glucose tolerance (NGT), indicating ß-cell dysfunction, and DI would worsen with progression from CF with NGT to CF-related diabetes (CFRD). METHODS: This was a cross-sectional study in 39 CF patients and 21 healthy controls (Con) who underwent oral glucose tolerance test (OGTT). Insulin sensitivity was estimated as (1/fasting insulin) and insulin secretion as (∆insulin 0-30min/∆glucose 0-30min). DI was calculated as (insulin sensitivity)×(insulin secretion). RESULTS: Among CF subjects, 14 had NGT, 20 had prediabetes and 5 had CFRD. Among the controls, 14 had NGT and 7 had prediabetes. DI was significantly lower in CF-NGT compared to Con-NGT (p=0.0035). DI was also lower in CFRD compared to CF-NGT (p=0.025). There were no significant relationships in the CF groups between DI and age, BMI, percent body fat or FEV1. CONCLUSION: ß-Cell function as measured by DI is reduced in CF patients compared to non-CF controls-even in CF-NGT-and is decreased further in CF patients with diabetes. If DI proves to be a predictor of the development of CFRD in larger studies, then it could be used to identify CF patients who are at particularly high risk, allowing early interventions aimed to delay or prevent CFRD.

Aging is associated with increased HbA1c levels, independently of glucose levels and insulin resistance, and also with decreased HbA1c diagnostic specificity.

AIM: To determine whether using HbA1c for screening and management could be confounded by age differences, whether age effects can be explained by unrecognized diabetes and prediabetes, insulin resistance or postprandial hyperglycaemia, and whether the effects of aging have an impact on diagnostic accuracy. METHODS: We conducted a cross-sectional analysis in adults without known diabetes in the Screening for Impaired Glucose Tolerance (SIGT) study 2005-2008 (n=1573) and the National Health and Nutrition Examination Survey (NHANES) 2005-2006 (n=1184). RESULTS: Both glucose intolerance and HbA(1c) levels increased with age. In univariate analyses including all subjects, HbA(1c) levels increased by 0.93 mmol/mol (0.085%) per 10 years of age in the SIGT study and by 1.03 mmol/mol (0.094%) per 10 years in the NHANES; in both datasets, the HbA(1c) increase was 0.87 mmol/mol (0.08%) per 10 years in subjects without diabetes, and 0.76 mmol/mol (0.07%) per 10 years in subjects with normal glucose tolerance, all P<0.001. In multivariate analyses of subjects with normal glucose tolerance, the relationship between age and HbA(1c) remained significant (P<0.001) after adjustment for covariates including race, BMI, waist circumference, sagittal abdominal diameter, triglyceride/HDL ratio, and fasting and 2-h plasma glucose and other glucose levels, as assessed by an oral glucose tolerance test. In both datasets, the HbA(1c) of an 80-year-old individual with normal glucose tolerance would be 3.82 mmol/mol (0.35%) greater than that of a 30-year-old with normal glucose tolerance, a difference that is clinically significant. Moreover, the specificity of HbA(1c) -based diagnostic criteria for prediabetes decreased substantially with increasing age (P<0.0001). CONCLUSIONS: In two large datasets, using different methods to measure HbA(1c), the association of age with higher HbA(1c) levels: was consistent and similar; was both statistically and clinically significant; was unexplained by features of aging; and reduced diagnostic specificity. Age should be taken into consideration when using HbA(1c) for the diagnosis and management of diabetes and prediabetes.

Glucose challenge test screening for prediabetes and undiagnosed diabetes.

AIMS/HYPOTHESIS: Diabetes prevention and care are limited by lack of screening. We hypothesised that screening could be done with a strategy similar to that used near-universally for gestational diabetes, i.e. a 50 g oral glucose challenge test (GCT) performed at any time of day, regardless of meal status, with one 1 h sample. METHODS: At a first visit, participants had random plasma and capillary glucose measured, followed by the GCT with plasma and capillary glucose (GCTplasma and GCTcap, respectively). At a second visit, participants had HbA(1c) measured and a diagnostic 75 g OGTT. RESULTS: The 1,573 participants had mean age of 48 years, BMI 30.3 kg/m(2) and 58% were women and 58% were black. Diabetes (defined by WHO) was present in 4.6% and prediabetes (defined as impaired glucose tolerance [2 h glucose 7.8-11.1 (140-199 mg/dl) with fasting glucose

Unrecognized glucose intolerance is not associated with depression. Screening for Impaired Glucose Tolerance study 3 (SIGT 3).

AIMS: To understand the metabolic and temporal links in the relationship between diabetes and depression, we determined the association between depressive symptoms and unrecognized glucose intolerance. METHODS: In a cross-sectional study, 1047 subjects without known diabetes were screened for diabetes or pre-diabetes using the oral glucose tolerance test and for depressive symptoms using the Patient Health Questionnaire (PHQ). RESULTS: Mean age was 48 years, body mass index 30 kg/m(2); 63% were female, 54% black, 11% previously treated for depression and 10% currently treated; 5% had diabetes and 34% pre-diabetes. Median PHQ score was 2 (interquartile range 0-5). Depressive symptoms did not increase with worsening glucose tolerance, after adjusting for age, sex, ethnicity, body mass index, family history, exercise, education and depression treatment. CONCLUSIONS: There is no association between depressive symptoms and unrecognized glucose intolerance. However, it remains possible that diagnosed diabetes, with its attendant health concerns, management issues, and/or biological changes, may be a risk for subsequent development of depression. Thus, patients with newly diagnosed diabetes should be counselled appropriately and monitored for the development of depression.

Effect of oestrogen plus progestin on the incidence of diabetes in postmenopausal women: results from the Women's Health Initiative Hormone Trial.

AIMS/HYPOTHESIS: Studies examining the effect of postmenopausal hormone therapy on concentrations of glucose, insulin and diabetes incidence have been inconclusive, in part because many of the studies were too small. We examined the effect of oestrogen plus progestin on diabetes incidence and insulin resistance. METHODS: The study was a randomised, double-blind trial comparing the effect of daily 0.625 mg conjugated equine oestrogens plus 2.5 mg medroxyprogesterone acetate with that of placebo during 5.6 years of follow-up. The participants were 15,641 postmenopausal women enrolled in the Women's Health Initiative Hormone Trial. These women were aged 50 to 79 and all had an intact uterus. Diabetes incidence was ascertained by self-report of treatment with insulin or oral hypoglycaemic medication. Fasting glucose, insulin, and lipoproteins were measured in a random sample at baseline and at 1 and 3 years. RESULTS: The cumulative incidence of treated diabetes was 3.5% in the hormone therapy group and 4.2% in the placebo group (hazard ratio 0.79, 95% CI 0.67-0.93, p=0.004). There was little change in the hazard ratio after adjustment for changes in BMI and waist circumference. During the first year of follow-up, changes in fasting glucose and insulin indicated a significant fall in insulin resistance in actively treated women compared to the control subjects (Year 1 to baseline between-group difference -0.22+/-0.10, p=0.03). INTERPRETATIONS/CONCLUSION: These data suggest that combined therapy with oestrogen and progestin reduces the incidence of diabetes, possibly mediated by a decrease in insulin resistance unrelated to body size. Future studies of alternative postmenopausal hormone therapy regimens and selective oestrogen agonists and/or antagonists should consider the effects of these regimens on insulin resistance and diabetes.

Long-term treatment of acromegaly with pegvisomant, a growth hormone receptor antagonist.

BACKGROUND: Pegvisomant is a new growth hormone receptor antagonist that improves symptoms and normalises insulin-like growth factor-1 (IGF-1) in a high proportion of patients with acromegaly treated for up to 12 weeks. We assessed the effects of pegvisomant in 160 patients with acromegaly treated for an average of 425 days. METHODS: Treatment efficacy was assessed by measuring changes in tumour volume by magnetic resonance imaging, and serum growth hormone and IGF-1 concentrations in 152 patients who received pegvisomant by daily subcutaneous injection for up to 18 months. The safety analysis included 160 patients some of whom received weekly injections and are excluded from the efficacy analysis. FINDINGS: Mean serum IGF-1 concentrations fell by at least 50%: 467 mg/L (SE 24), 526 mg/L (29), and 523 mg/L (40) in patients treated for 6, 12 and 18 months, respectively (p<0.001), whereas growth hormone increased by 12.5 mg/L (2.1), 12.5 mg/L (3.0), and 14.2 mg/L (5.7) (p<0.001). Of the patients treated for 12 months or more, 87 of 90 (97%) achieved a normal serum IGF-1 concentration. In patients withdrawn from pegvisomant (n=45), serum growth hormone concentrations were 8.0 mg/L (2.5) at baseline, rose to 15.2 mg/L (2.4) on drug, and fell back within 30 days of withdrawal to 8.3 mg/L (2.7). Antibodies to growth hormone were detected in 27 (16.9%) of patients, but no tachyphylaxis was seen. Serum insulin and glucose concentrations were significantly decreased (p<0.05). Two patients experienced progressive growth of their pituitary tumours, and two other patients had increased alanine and asparate aminotransferase concentrations requiring withdrawal from treatment. Mean pituitary tumour volume in 131 patients followed for a mean of 11.46 months (0.70) decreased by 0.033 cm(3) (0.057; p=0.353). INTERPRETATION: Pegvisomant is an effective medical treatment for acromegaly.

Meeting American Diabetes Association guidelines in endocrinologist practice.

OBJECTIVE: To determine whether American Diabetes Association (ADA) guidelines can be met in the context of routine endocrinology practice. RESEARCH DESIGN AND METHODS: Charts were reviewed for a group of patients who were examined in 1998, followed for > or = 1 year, and had two or more visits during that year. Process measures and metabolic outcomes were studied for patients with type 2 diabetes, and glycemic control was assessed for patients with type 1 diabetes. RESULTS: A total of 121 patients with type 2 diabetes had a mean age of 63 years, a mean BMI of 31 kg/m2, and a mean duration of diabetes of 12 years. Many had comorbidities or complications: 80% had hypertension, 64% had hyperlipidemia, 78% had neuropathy, 22% had retinopathy, and 21% had albuminuria. Management of type 2 diabetic patients was complex: 38% used oral hypoglycemic agents alone (54% of these were using two or more agents), 31% used oral hypoglycemic agents and insulin, and 26% used insulin alone; 42% of patients taking insulin therapy injected insulin three or more times per day. Within 12 months, 74% of patients had dilated eye examinations, 70% had lipid profiles, and 55% had urine albumin screening. Of the patients, 87% had a foot examination at their last visit. Blood pressure levels averaged 133/72 mmHg, cholesterol levels averaged 4.63 mmol/l, triglyceride levels averaged 1.99 mmol/l, HDL cholesterol levels averaged 1.24 mmol/l, and LDL cholesterol levels averaged 2.61 mmol/l. Random blood glucose levels averaged 8.0 mmol/l, and HbAlc levels averaged 6.9 +/- 0.1%. A total of 87% of patients had HbAlc levels < or = 8.0%. A total of 30 patients with type 1 diabetes had mean age of 44 years, a mean BMI of 26 kg/m2, and a mean duration of diabetes of 20 years. All type 1 diabetic patients used insulin and averaged 3.4 injections a day; their average HbAlc level was 7.1 +/- 0.2%, and 80% had HbAlc levels < or = 8.0%. CONCLUSIONS: Although endocrinologists must manage patients with multifaceted problems, complex treatment regimens yield glycemic control levels comparable with the Diabetes Control and Complications Trial and allow ADA guidelines to be met in a routine practice setting.

Treatment of acromegaly with the growth hormone-receptor antagonist pegvisomant.

BACKGROUND: Patients with acromegaly are currently treated with surgery, radiation therapy, and drugs to reduce hypersecretion of growth hormone, but the treatments may be ineffective and have adverse effects. Pegvisomant is a genetically engineered growth hormone-receptor antagonist that blocks the action of growth hormone. METHODS: We conducted a 12-week, randomized, double-blind study of three daily doses of pegvisomant (10 mg, 15 mg, and 20 mg) and placebo, given subcutaneously, in 112 patients with acromegaly. RESULTS: The mean (+/-SD) serum concentration of insulin-like growth factor I (IGF-I) decreased from base line by 4.0+/-16.8 percent in the placebo group, 26.7+/-27.9 percent in the group that received 10 mg of pegvisomant per day, 50.1+/-26.7 percent in the group that received 15 mg of pegvisomant per day, and 62.5+/-21.3 percent in the group that received 20 mg of pegvisomant per day (P<0.001 for the comparison of each pegvisomant group with placebo), and the concentrations became normal in 10 percent, 54 percent, 81 percent, and 89 percent of patients, respectively (P<0.001 for each comparison with placebo). Among patients treated with 15 mg or 20 mg of pegvisomant per day, there were significant decreases in ring size, soft-tissue swelling, the degree of excessive perspiration, and fatigue. The score fortotal symptoms and signs of acromegaly decreased significantly in all groups receiving pegvisomant (P< or =0.05). The incidence of adverse effects was similar in all groups. CONCLUSIONS: On the basis of these preliminary results, treatment of patients who have acromegaly with a growth hormone-receptor antagonist results in a reduction in serum IGF-I concentrations and in clinical improvement.

Glucose regulated production of human insulin in rat hepatocytes.

Insulin gene therapy requires that insulin secretion be coupled to metabolic requirements. To this end, we have developed an insulin transgene whose transcription is stimulated by glucose and inhibited by insulin. Glucose- and insulin-sensitive promoters were constructed by inserting glucose-responsive elements (GlREs) from the rat L-pyruvate kinase (L-PK) gene into the insulin-sensitive, liver-specific, rat insulin-like growth factor binding protein-1 (IGFBP-1) promoter. Glucose (5 to 25 mM) stimulated, and insulin (10-10 to 10-7 M) inhibited, luciferase expression driven by these promoters in primary cultured rat hepatocytes. The capacity of transfected hepatocytes to secrete mature, biologically active insulin was demonstrated using a human proinsulin cDNA (2xfur), modified to allow protein processing by endogenous endopeptidase activity. Medium conditioned by insulin-producing hepatocytes contained greater than 300 microU/ml immunoreactive insulin, while denaturing SDS-PAGE of an anti-insulin immunoprecipitate revealed bands with the mobilities of insulin A, and B chains. Biological activity of hepatocyte-produced insulin was demonstrated in a transfection assay, in which medium conditioned by insulin-producing hepatocytes exerted an effect similar to 10-7 M insulin. We then combined the glucose- and insulin-sensitive promoter with the modified human proinsulin cDNA to create a metabolically sensitive insulin transgene ((GlRE)3BP-1 2xfur). In both H4IIE hepatoma cells stably transfected with this construct, and normal rat hepatocytes (GlRE)3BP-1 2xfur-mediated insulin secretion increased in response to stimulation by glucose. Moreover, a capacity to decrease insulin production in response to diminishing glucose exposure was also demonstrated. We conclude that the transcriptional regulation of insulin production using these glucose- and insulin-sensitive constructs meets the requirements for application in a rodent model of insulin gene therapy. Gene Therapy (2000) 7, 205-214.

Muscle wasting in insulinopenic rats results from activation of the ATP-dependent, ubiquitin-proteasome proteolytic pathway by a mechanism including gene transcription.

In normal subjects and diabetic patients, insulin suppresses whole body proteolysis suggesting that the loss of lean body mass and muscle wasting in insulinopenia is related to increased muscle protein degradation. To document how insulinopenia affects organ weights and to identify the pathway for accelerated proteolysis in muscle, streptozotocin-treated and vehicle-injected, pair-fed control rats were studied. The weights of liver, adipose tissue, and muscle were decreased while muscle protein degradation was increased 75% by insulinopenia. This proteolytic response was not eliminated by blocking lysosomal function and calcium-dependent proteases at 7 or 3 d after streptozotocin. When ATP synthesis in muscle was inhibited, the rates of proteolysis were reduced to the same level in insulinopenic and control rats suggesting that the ATP-dependent, ubiquitin-proteasome pathway is activated. Additional evidence for activation of this pathway in muscle includes: (a) an inhibitor of proteasome activity eliminated the increased protein degradation; (b) mRNAs encoding ubiquitin and proteasome subunits were increased two- to threefold; and (c) there was increased transcription of the ubiquitin gene. We conclude that the mechanism for muscle protein wasting in insulinopenia includes activation of the ubiquitin-proteasome pathway with increased expression of the ubiquitin gene.

In vitro transcription of the rat insulin-like growth factor-I gene.

Although the liver is the major source of circulating insulin-like growth factor-I (IGF-I), relatively little is known about the regulation of IGF-I gene transcription in this tissue. Since transcripts are initiated largely in exon 1, we established an in vitro transcription system to evaluate activation of transcription via the major exon 1 initiation site. Transcription of a G-free cassette reporter was directed by rat IGF-I genomic fragments, and the adenovirus major late promoter was used as an internal control. Tissue specificity was demonstrated by a 60-90% decrease in transcripts with spleen extracts as compared with liver. 54 base pairs (bp) of upstream sequence were sufficient to direct IGF-I gene transcription, and activity increased 5-fold with 300 bp of upstream sequence. DNase I footprinting revealed four protected regions between -300 and -60 bp; binding was confirmed by gel shift analysis, and tissue specificity was demonstrated by reduced shifts with spleen extracts. The necessity of transcription factor binding to such sites was established by competition analysis, which revealed a specific decrease in IGF-I transcription in the presence of a competing fragment. Use of this in vitro transcription system should permit analysis of the function of individual transcription factors involved in regulation of IGF-I gene expression.

Preoperative localization of parathyroid tissue with technetium-99m sestamibi 123I subtraction scanning.

To evaluate the utility of technetium-99m (Tc-99m) sestamibi for visualization of functioning parathyroid tissue, 14 subjects underwent Tc-99m sestamibi 123I subtraction scanning as part of the preoperative evaluation for hyperparathyroidism. Informative scans were obtained in 13 subjects, including 7 patients with recurrent or persistent hyperparathyroidism, and correctly identified the location of the hyperfunctioning parathyroid tissue found at surgery. In all informative patients, hyperparathyroidism was due to adenomatous disease or hyperplasia secondary to renal failure. Successful scans were obtained with glands as small as 220 mg. In the lone patient in whom Tc-99m sestamibi scanning failed to localize hyperfunctioning parathyroid tissue, surgery revealed a 1700-mg hyperplastic parathyroid neoplasm in the neck. In no case did a Tc-99m sestamibi scan suggest parathyroid tissue where there was none. In 1 case, a patient presented with persistent hyperparathyroidism after 1 neck and a second combined neck and mediastinal exploration. Tc-99m sestamibi imaging revealed uptake in the periaortic region, and a 570-mg adenoma was found in the aortopulmonary window. Using only initial studies, prospective evaluation provided a sensitivity of 78.5% and a positive predictive value of 100%. After repeat studies in 5 patients, 2 of 3 patients with initially negative results and technically deficient scans became positive on restudy. Inclusion of these studies increased sensitivity to 93%. Tc-99m sestamibi 123I subtraction scanning appears to be a reliable noninvasive method for preoperative localization of hyperfunctioning parathyroid tissue.

Value of technetium 99m sestamibi iodine 123 imaging in reoperative parathyroid surgery.

BACKGROUND: The purpose of this study was to assess the contribution of technetium 99m sestamibi iodine 123 (T/S) imaging to preoperative and intraoperative management of patients with persistent hyperparathyroidism. METHODS: During a period of 10 months, all patients being prepared for reoperative parathyroid surgery (n = 10), two patients deemed significant operative risks (one patient with severe chronic obstructive pulmonary disease and one patient with severe cervical spine ankylosing spondylitis), and two patients who had undergone prior thyroid operation were studied with T/S imaging. Six patients undergoing reoperative surgery had undergone one, three had undergone two, and one had undergone three prior procedures. RESULTS: T/S imaging correctly localized 14 of 16 parathyroid tumors. By comparison, only 1 of 6 thallium technetium and 3 of 12 computed tomography (CT) scans (in seven patients) were positive. T/S imaging guided the reoperative surgical approach accurately in 12 of 14 patients, including one case of an undescended left lower gland at the level of the mandible and identification of a third gland on the left in another case. Sternal split was required to remove three lesions localized by T/S imaging, two beneath the aortic arch and one nestled in the aortopulmonary window in a patient who had undergone two prior procedures including a sternal split. In these three cases T/S imaging was particularly useful, because CT scans, thallium technetium scans, magnetic resonance imaging, and arteriography were not diagnostic. The outcome after operation was favorable in all 14 cases, with correction of hypercalcemia and no permanent laryngeal nerve injuries or hypocalcemia. CONCLUSIONS: We concluded that T/S imaging is more accurate than thallium technetium and CT scans in evaluation of patients with persistent hyperparathyroidism.

Nutrition and somatomedin. XXIII. Molecular regulation of IGF-I by amino acid availability in cultured hepatocytes.

The poor growth associated with protein-calorie malnutrition occurs despite circulating growth hormone levels that are normal or elevated and is thought to be mediated partly by blunted generation of insulinlike growth factor I (IGF-I) in the liver. To explore underlying mechanisms, we asked whether altered availability of amino acids could regulate hepatic IGF-I release independent of the contributions of regulatory hormones. Normal rat hepatocytes were isolated by collagenase digestion and maintained in serum-free medium with fixed concentrations of insulin and dexamethasone. Levels of immunoassayable albumin and IGF-I accumulation in daily changes of medium were sustained for 3-5 days, and all studies were performed within this period. Cellular viability and content of DNA were unaffected by deprivation of the essential amino acids lysine or tryptophan and the nonessential amino acids cysteine and/or cystine. However, deletion of tryptophan or lysine from the culture medium led to 63 and 76% declines in IGF-I release, respectively (both P less than 0.001 vs. complete medium), although omission of cysteine or cysteine plus cystine produced no significant change. Over 5 days of culture, release of albumin was maintained in complete medium, but omission of tryptophan depressed albumin release over days 2-5 (P less than 0.001). In complete medium, IGF-I release rose for 3 days and then declined. In tryptophan-deficient medium, IGF-I levels were comparable to control values after 24 h but did not rise at 48 h and then fell rapidly after 72 h in culture, with values significantly below levels in complete medium (all P less than 0.005).(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of clonidine on growth and plasma somatomedin C levels of young rats

To study effects of clonidine on growth and plasma somatomedin C (SmC) lelvels, 42 male Wistar rats aged 28 days and weighing 75 to 105 g were given clonidine (1,5 microng/ml in drinking water), or filtered water alone and were weighed weekly. After 0,4 and 8 weeks, the animals were sacrificed under ether anesthesia, their length was measured and blood was collected by cardiac puncture for measurement of SmC concentration. Growth and the weigh/lengh ratio were lower, and plasma SmC levels (mean ñ SEM) were greater in the treated groups after 4 (616 ñ 44.7 vs 433.2 ñ 39.38 ng/ml, P < 0.01) and 8(595.2 28.3 vs 412.66 ñ 39.01 ng/ml, P < 0.01) weeks of treatment, suggesting that clonidine treatment increased growth hormone secretion. In other experiments, treated showed increased food intake only during the first week of treatment and decreased epididymal fat weight afther 3 weeks (1.412 ñ 0.0536 vs 1.6 ñ 0.1335 mg/100 g body weight, P < 0.01). The results suggest that clonidine acts at the level of the central nervous system involving transitory modulation of food intake, as well as on the regulation of energy metabolism

Evidence for multifactorial origin of diabetes-induced embryopathies.

Serum factors characteristically altered in the diabetic state, e.g., glucose, ketone bodies (beta-hydroxybutyrate), and somatomedin inhibitors, induce dysmorphogenesis with or without growth retardation in rodent embryos in whole-embryo culture. Furthermore, serum from diabetic animals, which contains combinations of altered factors, is teratogenic, thereby implying that the diabetic embryopathy is of a multifactorial origin. However, a detailed investigation with various combinations of factors at known concentrations to test this hypothesis has not been conducted. Therefore, we employed combinations of hyperglycemia (300 and 600 mg/dl; 16.6 and 33.3 mM), hyperketonemia (8 and 16 mM D-beta-hydroxybutyrate), and an 800- to 1000-Mr somatomedin-inhibitor serum fraction (at an amount equal to that found in 0.05 and 0.1 ml of serum from a diabetic rat per deciliter culture medium), which represented doses with low teratogenic potential, to determine if interactions of the factors could occur that would increase the risk of malformations in mouse embryos exposed in whole-embryo culture during gastrulation and neurulation. The results demonstrate that glucose and D-beta-hydroxybutyrate can act synergistically to produce growth retardation and additively to induce malformations. The addition of the somatomedin inhibitor exacerbates the induction of malformations produced by the ketone body and glucose. Thus, the origin of the diabetic embryopathy may be multifactorial, involving several altered maternal factors.