The Merits and the Pitfalls of Low Carbohydrate Diet: A Concise Review.

Low carbohydrate diets (LCD) may help body weight loss and glycemic control in diabetes but their long-term consequences are not known. The aim of this review is to highlight the contrast between the potential benefits of short term LCD and the adverse health effects of long-term consumption of LCD. LCD can enhance weight loss in the short term although its effect is small and not sustainable. In people with diabetes and insulin resistance, LCD is helpful in achieving glycemic control. However, there are untoward side effects especially when carbohydrates are severely restricted (< 50 gm a day) to induce ketosis. The latter curbs appetite but also may cause nausea, fatigue water and electrolyte losses and limits exercise capacity. In addition, observational studies suggest that low carbohydrate diets (< 40% energy form carbohydrates) as well as very high carbohydrate diets (> 70% energy from carbohydrate) are associated with increased mortality. The available scientific evidence supports the current dietary recommendations to replace highly processed carbohydrates with unprocessed carbohydrates as well as limiting added sugars in the diet.

Academic advancement of clinician educators: why is it so difficult?

The role of clinician educators (CEs) in institutions and medical centres continues to be vital without any doubt. Although there has been more than a century since Sir William Osler established the role of the CE and the tradition by encouraging bed-side teaching, there is still a lack of consensus on the attributes that define a 'clinician-educator'. The concept of a superior clinician who is also a dedicated teacher seems to fit the description of a CE but most often seems insufficient to support the CE's academic advancement.

The effect of healthcare provider education on diabetes management of hospitalised patients.

BACKGROUND: The importance of optimising blood glucose (BG) control in hospitalised patients is widely accepted. To determine whether focused education of physicians and nurses would result in measurable changes in glycaemic control, the effect of a diabetes-focused educational programme on point of care (POC) BG measures was monitored. METHODS: This programme included 2 h symposium and 2 h interactive session. The POC BG measures were determined at 2-month period prior to implementing the programme and the ensuing 7 months after. Outcome parameters included the mean BG values, the incidence of hyperglycaemia (BG > 180 mg/dl) and hypoglycaemia (BG < 60 mg/dl). The outcome parameters were analysed by comparing the Internal Medicine (target service) to other such as Neurology and Surgical Trauma where no programme was offered. RESULTS: On Internal Medicine, the mean BG decreased soon after implementing the programme and stayed lower than the baseline values over 7 months. The changes were significant at the third, fourth, seventh and the ninth month of the study. Hyperglycaemia decreased significantly (p < 0.05) on the third, fourth, seventh and eighth month, while hypoglycaemia increased following the education programmes. On Neurology and Surgical Trauma, the mean BG values were significantly higher, and hypoglycaemia was significantly lower during the same time frame. CONCLUSIONS: Implementing an educational programme for healthcare providers had significant effects on the lowering of mean BG values and the incidence of hyperglycaemia, but increased the risk of hypoglycaemia. The merits of such programmes need to be tested before their widespread implementation.

The incidence of Hashimoto's disease in nodular goitre: the concordance in serological and cytological findings.

OBJECTIVE: To determine the incidence of Hashimoto's disease in nodular goitre and to ascertain the degree of the concordance between serological and cytological findings. METHODS: We retrospectively reviewed data from 188 patients who underwent a fine needle aspiration biopsy of the thyroid for uninodular or multinodular goitre with a documented serological level of antithyroid peroxidase (TPO) antibodies. AntiTPO antibodies were measured by immunochemiluminescent assay (Quest Diagnostics, Madison, NJ, USA). RESULTS: The study cohort consisted of 170 female and 18 male patients with a mean (+/- SD) age of 47.8 +/- 14.9 years. AntiTPO antibodies were positive in 74 (39.36%) of the individuals and negative in 114 (60.63%). The cytodiagnoses were as follows: 5 (2.6%) cancerous, 18 (9.5%) suspicious, 12 (6.3%) inadequate, 92 (48.9%) benign and 61 (32.4%) consistent with chronic lymphocytic thyroiditis (CLT). For further analysis, we excluded all inadequate specimens. Based on the final sample of 176 patients, the sensitivity and specificity of antiTPO antibody test to detect CLT in nodular goitre were estimated to be 76.38% and 94.23% respectively. The prevalence of CLT in nodular goitre based on cytological criteria was (35.46%) compared with (31.97%) goitre based on positive antiTPO titres only. CONCLUSION: There is a high degree of concordance between serological and cytological findings of CLT in people with nodular goitres. The high prevalence of CLT in nodular goitre justifies the use of antiTPO antibodies as part of the workup in this population.

Diagnosis and management of hyponatraemia in hospitalised patients.

Hyponatraemia is a commonly encountered electrolyte abnormality in hospitalised patients and is associated with significant morbidity and mortality. The fact that most cases of hyponatraemia are the result of water imbalance rather than sodium imbalance underscores the role of antidiuretic hormone (ADH) in the pathophysiology. Hyponatraemia can be classified according to the measured plasma osmolality as isotonic, hypertonic or hypotonic. Hyponatraemia with a normal plasma osmolality usually indicates pseudohyponatraemia, while hyponatraemia because of a high plasma osmolality is typically caused by hyperglycaemia. After excluding isotonic and hypertonic causes, hypotonic hyponatraemia is further classified according to the volume status of the patient as hypovolaemic, hypervolaemic or euvolaemic. Hypovolaemic hyponatraemia is accompanied by extracellular fluid (ECF) volume deficit, while hypervolaemic hyponatraemia manifests with ECF volume expansion. The syndrome of inappropriate ADH (SIADH) should be suspected in any patient with euvolaemic hyponatraemia with a urine osmolality above 100 mOsm/kg and urine sodium concentration above 40 mEq/l. In the management of any hyponatraemia regardless of the patient's volume status, it is advised to restrict free water and hypotonic fluid intake. Hypertonic saline and vasopressin antagonists can be used to correct symptomatic hyponatraemia. The rate of correction is dependent upon the duration, degree of hyponatraemia and the presence or absence of symptoms. Symptomatic acute hyponatraemia (< 48 h) is a medical emergency requiring rapid correction to prevent the worsening of brain oedema. In asymptomatic patients with chronic hyponatraemia (> 48 h or unknown duration), fluid restriction and close monitoring alone are sufficient, while a slow correction by 0.5 mEq/l/h may be attempted in symptomatic patients. Excessive rapid correction should be avoided in both acute and chronic hyponatraemia, because it can lead to irreversible neurological complications including central osmotic demyelination.

Clinical utility of anion gap in deciphering acid-base disorders.

The anion gap (AG) measurement is a very useful tool in the evaluation of patients with acid-base disorders. Once metabolic acidosis is identified, AG will provide the important first step in the differential diagnosis of disorders that either increase the AG and those that leave the AG unchanged. Delta gap is the comparison between change (delta) in the AG and the change (delta) in bicarbonate (HCO(3)(-)). Delta ratio, defined as delta AG:delta HCO(3)(-) is usually 1:1 in patients with an uncomplicated high AG acidosis. A value below 1:1 suggests a combined high and normal AG acidosis. A value above 2:1 suggests a combined metabolic alkalosis and a high AG acidosis. Urine AG (unmeasured anions-unmeasured cations) is an indirect estimate of the urine NH(4)(+) excretion. It is typically negative in patients with normal AG metabolic acidosis secondary to diarrhoea. Utilisation of AG calculations helps clinicians in identifying and treating acid-base disorders.

Low serum high-density lipoprotein cholesterol in obese subjects with normal serum triglycerides: the role of insulin resistance and inflammatory cytokines.

BACKGROUND: The cause of obesity-related low HDLc in the absence of hypertriglyceridemia is not known. SUBJECTS & METHODS: A total of 32 subjects with a body mass index (BMI)(kg/m(2)) greater than 30 and normal serum triglycerides (<150 mg/dl) were identified. RESULTS: People with low HDLc (n = 16) compared to those with normal HDLc (n = 16) had higher BMI (37.53 +/- 4.54 vs. 33.99 +/- 3.65 kg/m(2), p < 0.021), higher body fat weight (42.59 +/- 9.51 vs. 34.76 +/- 8.7 kg, p < 0.023), and higher insulin resistance index (3.75 +/- 2.51 vs. 1.95 +/- 1.10, p < 0.013). Seven subjects with low HDLc and none of those with normal HDLc, had elevated serum tumor necrosis factor alpha and/or interleukin-6 (p < 0.010). CONCLUSIONS: Low HDLc levels can occur in obesity independently of elevated serum triglycerides and may be secondary to elevated serum levels of inflammatory cytokines.

Glyburide/metformin combination product is safe and efficacious in patients with type 2 diabetes failing sulphonylurea therapy.

AIM: To compare the efficacy, safety and tolerability of a fixed combination glyburide/metformin preparation with those of glyburide or metformin alone in patients with type 2 diabetes inadequately controlled by sulphonylurea, diet and exercise. METHODS: In this 16-week, randomized, double-blind, parallel group study, 639 patients with inadequate glycaemic control on at least half-maximal dose of sulphonylurea were randomly assigned to: glyburide 10 mg b.i.d. (n = 164); metformin 500 mg (n = 153); glyburide/metformin 2.5 mg/500 mg (n = 160); or glyburide/metformin 5 mg/500 mg (n = 162). Titration was allowed to maximum doses of 2000 mg for metformin or 10 mg/2000 mg and 20 mg/2000 mg for glyburide/metformin 2.5 mg/500 mg and 5 mg/500 mg respectively. The primary outcome measure was HbA1c level after 16 weeks; secondary end-points included fasting and 2-h post-prandial plasma glucose. Adverse events (AEs) were recorded and summarized by treatment group. RESULTS: Both strengths of glyburide/metformin equally reduced mean HbA1c by 1.7% more than did glyburide alone (p < 0.001), and by 1.9% more than did metformin alone (p < 0.001). Final mean fasting plasma glucose concentrations were also lower in both glyburide/metformin groups than in the glyburide (-2.8 mmol/l, -51.3 mg/dl; p < 0.001) and metformin groups (-3.6 mmol/l, -64.2 mg/dl; p < 0.001). Safety and tolerability were similar across all treatment groups, except for a higher incidence of gastrointestinal AEs in the metformin monotherapy group, and more patients reporting mild or moderate symptoms of hypoglycaemia while taking glyburide/metformin. CONCLUSIONS: Both glyburide/metformin tablet strengths produced, with equal efficacy, significantly better glycaemic control than monotherapy with either agent. These data also confirm that glycaemic efficacy does not require maximal sulphonylurea doses in combination with metformin.

Obesity: a rational target for managing diabetes mellitus.

Obesity is a growing public health problem worldwide. It is a particularly common problem among individuals with type 2 diabetes mellitus. The magnitude of obesity, the central location of fat, and a history of weight gain are independent risks for developing diabetes mellitus. Potential factors implicated in the pathogenesis of diabetes mellitus in obese patients include increased plasma free fatty acid concentrations, increased production of cytokines, increased leptin levels, and increased levels of a recently discovered protein called resistin. Epidemiological and interventional studies suggest that even modest loss of body weight, either by changes in lifestyle or pharmacological means is associated with significant amelioration of insulin resistance and improvement in diabetes mellitus control. Treatment of obesity is an important therapeutic goal in the management of patients with type 2 diabetes mellitus.

Role of repeated fine-needle aspiration of thyroid nodules with benign cytologic features.

OBJECTIVE: To determine the role of repeated fine-needle aspiration (FNA) biopsy in the evaluation of thyroid nodules initially classified as benign. METHODS: We retrospectively reviewed data on 235 patients with clinically palpable thyroid nodules who underwent a repeated FNA biopsy after an initially benign diagnosis. All the nodules were evaluated and biopsies were obtained by the same endocrinologist. Cytodiagnoses were divided into four major categories: inadequate, benign, suspicious, or malignant. RESULTS: The study cohort consisted of 211 female and 24 male patients with a mean age of 47.1 years. The repeated FNA cytodiagnoses were as follows: 204 (86.8%) remained benign and 19 (8.1%), 11 (4.7%), and 1 (0.4%) became inadequate, suspicious, and malignant, respectively. All patients with benign or inadequate cytologic results on repeated FNA who underwent thyroid surgical resection had benign histologic findings (N = 23). The mean follow-up period between the initial and the last benign FNA cytodiagnosis in the 186 patients without surgical intervention was 1,078 days (2.95 years). Nine of 11 patients with suspicious cytologic results underwent a thyroid surgical procedure, which revealed a benign lesion in 7 and malignant disease in 2 (18%). The other two patients with suspicious cytologic findings had a 13-year clinical follow-up without any clinical evidence of a thyroid malignant lesion. The only patient with malignant cytologic findings on repeated FNA (a 76-year-old woman) refused surgical treatment and was lost to follow-up. CONCLUSION: Although the yield of finding a malignant lesion on repeated FNA biopsy in the follow-up of a presumably benign thyroid nodule may be low, rebiopsy reduces the rate of false-negative diagnosis from an average of 5.2% to <1.3%.

Malondialdehyde modification of proteins in vitro is enhanced in the presence of acetaldehyde.

To test the hypothesis that the cardioprotective effect of alcohol is related to the inhibition of malondialdehyde (MDA) modification of proteins by acetaldehyde (AA), we studied the effect of AA on MDA modification of bovine serum albumin (BSA) in vitro. BSA was incubated simultaneously with a fixed concentration of MDA (70 mM) and different concentrations of AA (120, 60, 30, 10, or 0 mM) for 24 h at 37 degrees C. The MDA-modified or AA-modified BSA was quantitated with immunoblotting by using specific anti-MDA and specific anti-AA protein antisera, respectively. In another set of experiments, BSA was incubated sequentially, first with different concentrations of AA and then with 70 mM of MDA. In both incubation protocols, the presence of AA and AA modification of BSA enhanced MDA binding. These in vitro observations suggest that the putative cardioprotective effects of alcohol or wine cannot be ascribed to AA-mediated reduction in MDA protein formation, a possible biochemical pathway of accelerated atherosclerosis.

Regulation of apoA1 gene expression with acidosis: requirement for a transcriptional repressor.

Serum apolipoprotein A(1) (apoA(1)) concentration is inversely correlated with the risk of premature atherosclerosis. Serum apoA(1) concentrations are regulated, in part, at the transcriptional level. ApoA(1) mRNA is synthesized primarily in the liver and small intestine, under the direction of a number of signaling molecules and tissue-specific regulatory elements. Previously, we demonstrated that extracellular acidosis suppresses apoA(1) mRNA levels at the level of transcription. Here we demonstrate that intracellular acidosis, in the absence of extracellular pH changes, represses apoA(1) promoter activity. Repression occurs through a pH responsive element (pH-RE) located within the apoA(1) gene promoter. Acidosis increases the specific DNA binding activity of a putative repressor protein within the immediate 5'-flanking region of the apoA(1) gene. The cis-element that binds the putative repressor protein contains a negative thyroid hormone response element (nTRE) located 3' and adjacent to the apoA(1) TATA box. Mutation of the nTRE/pH-RE abrogates protein binding and alters the activity of reporter genes controlled by this element. Repression by acidosis did not require de novo mRNA and protein synthesis. Inhibition of tyrosine kinase activity and diacylglycerol-stimulated protein kinase C (PKC) signaling pathways with tyrophostin A47 and phorbol myristate acetate, respectively, did not affect the repression of apoA(1) promoter activity with acidosis. These results suggest that transcriptional repression of the apoA(1) gene by alterations in ambient pH is associated with enhanced DNA binding activity of a repressor protein, through a mechanism which appears to be independent of de novo mRNA and protein synthesis, tyrosine kinase activity, or PKC activation.

Age-related changes in rat hepatic acetyl-coenzyme A carboxylase.

Acetyl-CoA carboxylase (ACC) catalyzes the rate-limiting step in the synthesis of long-chain fatty acids. Since aging influences adiposity, we studied the activity of ACC and its mRNA content in livers of 4-, 12-, and 24-month-old male Fischer 344 rats. The mean (+/- SEM) activity of ACC (mU/mg protein) in liver homogenates from 4-month-old rats was 1.01 +/- 0.14. There was an 80% increase in activity (1.83 +/- 0.27) in 12-month-old rats (P < 0.01). However, there was significantly less activity (0.46 +/- 0.06) in livers of 24-month-old rats (P < 0.001). The total activity of ACC (per g liver) followed the same trend. The enzyme from all age groups was purified by avidin-affinity chromatography. The purified preparation migrated as a major protein band (M(r) 262,000) on sodium dodecyl sulfate (SDS)-polyacrylamide gels. The specific activity of the purified preparation was 1.5, 1.8, and 1.8 U/mg for 4-, 12-, and 24-month-old rats, respectively. The alkali-labile phosphate content was 5.66 +/- 0.17, 5.64 +/- 0.21, and 6.21 +/- 0.35 mols P(i)/mole subunit for 4-, 12-, and 24-month-old rats, respectively. These age-related differences were not significant. The hepatic ACC mRNA measured by ribonuclease protection assay when corrected for G3PDH mRNA was significantly reduced in 24-month-old rats (0.24 +/- 0.03) compared with 12-month-old (0.58 +/- 0.04) or 4-month-old rats (0.43 +/- 0.007) P < 0.01. In summary: (i) Aging in rats is associated with significant changes in ACC activity; (ii) the purified ACC preparations from the three age groups had similar specific activity and similar phosphate content; and (iii) the changes in ACC mRNA content of the liver paralleled the changes in total enzyme activity when 12-month-old rats were compared with 24-month-old rats whereas the increase in ACC activity in 12-month-old rats compared with 4-month-old rats could not be ascribed to changes in hepatic mRNA levels. These results indicate that the age-related changes in hepatic ACC occur at a post-translational level during early years of aging and at a pretranslational level at late states of senescence. These changes may contribute to the age-related alterations in body adiposity.

Age-related changes in plasma leptin binding activity in rats: A comparison of a simple acid-ethanol precipitation technique with column chromatography.

A novel assay for measuring the free leptin fraction was developed and validated against a chromatographic technique. The assay used acid-ethanol extraction (AEE) for separation of bound/free leptin moieties. The interassay coefficient of variation was 3.9%. The specificity for leptin binding was confirmed by incubation with 1 microg of unlabeled rat leptin that effectively competed with radiolabeled leptin whereas human growth hormone and interleukin-6 were ineffective in competing with radiolabeled leptin binding. Scatchard analysis of competitive binding experiments with rat plasma demonstrated a linear relationship with a binding affinity of 0.3-0.6 x 109 M-1. This novel assay was used to determine if age-related insensitivity to leptin action is secondary to altered serum leptin binding. Rats at various age groups were studied for changes in body adiposity and serum total and free leptin concentrations. Serum free leptin concentrations (ng/ml mean +/- SEM) were significantly increased in 24-month-old rats (5.56 +/- 0. 21) compared with 18-month-old rats (4.76 +/- 0.17) (P < 0.01) despite similar body weight and adiposity of the two age groups. The increase in plasma free leptin concentrations in 12-month-old rats (3.86 +/- 0.28) and 6-month-old rats (2.05 +/- 0.06) relative to 3-month-old rats (1.37 +/- 0.06) (P < 0.001) was out of proportion to the increase in body adiposity in aging rats. It is concluded that aging in rats is associated with relative insensitivity to leptin. This change cannot be attributed to increased plasma binding or to a reduction in the leptin free fraction.

A rational approach to drug therapy of type 2 diabetes mellitus.

Several new pharmacological agents have recently been developed to optimise the management of type 2 (non-insulin-dependent) diabetes mellitus. The aim of this article is to briefly review the various therapeutic agents available for management of patients with type 2 diabetes mellitus and to suggest a potential approach to drug selection. There are three general therapeutic modalities relevant to diabetes care. The first modality is lifestyle adjustments aimed at improving endogenous insulin sensitivity or insulin effect. This can be achieved by increased physical activity and bodyweight reduction with diet and behavioural modification, and the use of pharmacological agents or surgery. This first modality is not discussed in depth in this article. The second modality involves increasing insulin availability by the administration of exogenous insulin, insulin analogues, sulphonylureas and the new insulin secretagogue, repaglinide. The most frequently encountered adverse effect of these agents is hypoglycaemia. Bodyweight gain can also be a concern, especially in patients who are obese. The association between hyperinsulinaemia and premature atherosclerosis is still a debatable question. The third modality consists of agents such as biguanides and thiazolidinediones which enhance insulin sensitivity, or agents that decrease insulin requirements like the alpha-glucosidase inhibitors. Type 2 diabetes mellitus is a heterogeneous disease with multiple underlying pathophysiological processes. Therapy should be individualised based on the degree of hyperglycaemia, hyperinsulinaemia or insulin deficiency. In addition, several factors have to be considered when prescribing a specific therapeutic agent. These factors include efficacy, safety, affordability and ease of administration.

Effects of ketoacidosis on rat apolipoprotein A1 gene expression: a link with acidosis but not with ketones.

To determine if ketoacidosis contributes to reduced apolipoprotein A1 (apoA1) expression in insulin-deficient diabetic rats, we examined the regulation of apoA1 gene expression in response to changes in ambient pH or ketone body concentrations. Hepatic apoAI mRNA levels were reduced 42% in diabetic rats relative to nondiabetic controls (means+/-s.d.; 321.8+/-43.7 vs 438.7+/-58.8 arbitrary units; P<0.03). Neither endogenous apoA1 mRNA nor transcriptional activity of the rat apoA1 gene promoter (from -474 to -7) were altered by sodium butyrate or isobutyramide (0.3 mM to 10 mM) in Hep G2 or Caco-2 cells. Rat hepatic and intestinal apoA1 mRNA levels, and plasma apoA1 concentration, were not altered 24 h after isobutyramide administration (500 mg/kg by gavage). When the effect of altering ambient pH within a wide range commonly encountered in vivo was studied, acidosis (pH 6.7), relative to alkalosis (pH 7.9), decreased apoAI mRNA levels relative to glyceraldehyde-3-phosphate dehydrogenase mRNA by 47% in Hep G2 cells (P<0.025) and by 24% in Caco-2 cells (P<0.017). Acidosis did not alter cytomegalo virus (CMV)-beta-galactosidase activity, or the activity of the simian virus (SV40) early-region promoter, in either cell line transfected with the respective constructs. The lowering of ambient pH was associated with a graded reduction in apoAI promoter activity. At pH 6.7, apoAI promoter activity was reduced by 75% compared with promoter activity at pH 7.9. These observations indicate that acidosis, but not ketosis, contributes to the reduction in apoA1 expression during diabetic ketoacidosis by down-regulating apoAI promoter activity.

Efficacy and safety of sibutramine in obese white and African American patients with hypertension: a 1-year, double-blind, placebo-controlled, multicenter trial.

BACKGROUND: Obesity is a highly prevalent medical condition and is commonly accompanied by hypertension. This study assessed the efficacy and safety of treatment with sibutramine hydrochloride for promoting and maintaining weight loss in obese patients with controlled hypertension, including a subset analysis of African American patients. PATIENTS AND METHODS: Obese patients with a body mass index (BMI, calculated as weight in kilograms divided by the square of height in meters) between 27 and 40 and a history of hypertension controlled with a calcium channel blocker (with or without concomitant thiazide diuretic treatment) were randomized to receive sibutramine (n = 150) or placebo (n = 74) with minimal behavioral intervention for 52 weeks. African Americans constituted 36% of enrolled patients. Efficacy assessments were body weight and related parameters (BMI and waist and hip circumferences), metabolic parameters (serum levels of triglycerides, high-density lipoprotein cholesterol [HDL-C], low-density lipoprotein cholesterol [LDL-C], total cholesterol, glucose, and uric acid), and quality-of-life measures. Safety assessments included recording of blood pressure, pulse rate, adverse events, and reasons for discontinuation. RESULTS: For patients receiving sibutramine, weight loss occurred during the first 6 months of the trial and was maintained to the end of the 12-month treatment period. Among patients receiving sibutramine, 40.1% lost 5% or more of body weight (5% responders) and 13.4% lost 10% or more of body weight (10% responders) compared with 8.7% and 4.3% of patients in the placebo group, respectively (P<.05). Changes in body weight were similar among African Americans and whites. Sibutramine-induced weight loss was associated with significant improvements in serum levels of triglycerides, HDL-C, glucose, and uric acid. Waist circumference and quality-of-life measures also improved significantly in patients receiving sibutramine. Sibutramine-treated patients had small but statistically significant mean increases in diastolic blood pressure (2.0 mm Hg) and pulse rate (4.9 beats/min) compared with placebo-treated patients (-1.3 mm Hg and 0.0 beats/min; P<.05); these changes were similar among African Americans and whites. Most adverse events were mild to moderate in severity and transient. The most common adverse event resulting in discontinuation among patients receiving sibutramine was hypertension (5.3% of patients receiving sibutramine vs 1.4% of patients receiving placebo). CONCLUSIONS: In obese patients with controlled hypertension, sibutramine was an effective and well-tolerated treatment for weight loss and maintenance. Sibutramine-induced weight loss resulted in improvements in serum levels of triglycerides, HDL-C, uric acid, and glucose, and in waist circumference and quality-of-life measures. Blood pressure and heart rate increased by a small amount. Efficacy and safety profiles for sibutramine among African American and white obese patients with controlled hypertension were similar.

Dose-response profile of acarbose in older subjects with type 2 diabetes.

OBJECTIVE: To examine the dose-response relationship of acarbose, an alpha-glucosidase inhibitor, in older subjects with type 2 diabetes. RESEARCH DESIGN: Fourteen subjects with type 2 diabetes who were over 65 years old were studied. Five subjects had been treated with diet alone and 9 were receiving a sulfonylurea. The subjects underwent a meal tolerance test in the presence of varying doses of acarbose (0, 25, 50, and 100 mg) on 4 occasions, each 1 week apart. The test meal was chosen to include food items commonly consumed during breakfast in the United States. The 483-kcal meal consisted of 51% of calories in the form of carbohydrates, 14% protein, and 35% fat. The serum glucose, insulin, and triglyceride levels were measured at 0, 1, and 2 hours after the meal. RESULTS: The postprandial hyperglycemic response to the test meal was significantly reduced with 25 mg of acarbose compared with baseline values. Increasing doses of acarbose to 50 or 100 mg had no significant additional ameliorating effects on postprandial hyperglycemia. Postprandial insulin or triglyceride levels were not significantly altered with single dose acarbose treatment. CONCLUSIONS: It is concluded that the acute efficacy of acarbose is near maximal at 25 mg when the meal size does not exceed 483 kcal and contains only 61 gm of carbohydrates.

Effect of amitriptyline on the messenger RNA of thyroid hormone-responsive genes in rat cerebral tissue.

To determine the molecular mechanisms of the potentiating effect of thyroid hormones (TH) on the therapeutic efficacy of tricyclic antidepressants (TCA), the expression of two known TH-responsive mRNAs was measured in control rats and rats treated with triiodothyronine (T3, 10 microg/100 g for 10 days), amitriptyline (10 mg/kg for 10 days), or combined T3 and amitriptyline. Northern blot analysis was carried out to measure the cerebral tissue content of a novel translational repressor (NAT-1) and another thyroid hormone-responsive (THR) mRNA. Rats treated with the combination of T3 and amitriptyline had significantly higher NAT-1 expression (2691.1+/-134.1 arbitrary units) than rats treated with T3 only (1688.5+/-77.8) or with amitriptyline only (1452.5+/-87.5) or the untreated control rats (731.3+/-23.0), P<0.01. Amitriptyline treatment did not alter the expression of THR mRNA or THR protein in either control or T3-treated rats. It is concluded that alterations in the expression of selective T3 responsive genes in cerebral tissue could be a mechanism of the known T3 potentiation of the therapeutic efficacy of TCA.

Serum leptin response to endogenous hyperinsulinemia in aging rats.

To determine if aging is associated with altered serum leptin response to diet-induced changes in endogenous hyperinsulinemia, male Fisher 344 (F344) rats at different age groups were studied while on regular rat chow and following 10 days of experimental diets consisting of 60% of the weight as fructose or glucose. The serum leptin concentration (ng/ml) gradually increased from basal levels of 2.5+/-0.1 at age of 4 months to 3.7+/-0.1, 6.9+/-0.9, 9. 4+/-0.3 and 8.9+/-1.1 at 6, 12, 18 and 24 months of age, respectively (P<0.001). Hyperinsulinemia associated with 60% fructose diet was associated with increased serum leptin levels in 4, 12, and 24 month old rats to 5.1+/-0.8, 6.7+/-1.2, and 8.6+/-1.1, respectively (P<0.001). Feeding 60% glucose diet also was associated with increased serum leptin levels in 4, 12 and 24 month old rats to 7.6+/-0.6, 7.2+/-0.7, and 9.1+/-1.1, respectively (P<0.001). Restricting dietary intake to 60% of the calories consumed by control rats for 10 days resulted in a decrease in serum leptin to 1.0+/-0.02 in 4 month old rats and 2.5+/-0.4 in 24 month old rats (P<0.01). It is concluded that aging in F344 rats is associated with increased serum leptin concentrations. However, diet-related hyperinsulinemic effect on leptin is blunted in aging rats although leptin response to caloric restriction is maintained. The inability of aging rats to mount hyperleptinemic response to dietary changes may contribute to the age-related increase in adiposity.