Empagliflozin: a new treatment option for patients with type 2 diabetes mellitus.

Empagliflozin is an oral sodium-glucose cotransporter 2 (SGLT2) inhibitor that reduces hyperglycemia in type 2 diabetes mellitus (T2DM) by decreasing renal glucose reabsorption and promoting urinary glucose excretion. In clinical trials, empagliflozin demonstrated significant improvements in glycemic control, as monotherapy and in combination regimens. In addition, empagliflozin was associated with weight loss and moderate reductions in blood pressure. In the EMPA-REG OUTCOME study, empagliflozin significantly reduced the risk of the composite primary endpoint of cardiovascular death, nonfatal myocardial infarction and nonfatal stroke. Across the trials in general, empagliflozin was well tolerated, with no increased risk of hypoglycemia except when used with an insulin secretagogue or insulin. An increased risk of genital infections and urinary tract infections has been reported, although the association is less clear for urinary tract infections. Overall, empagliflozin appears to be a promising treatment for T2DM.

A review of the safety and efficacy data for insulin glargine 300 units/ml, a new formulation of insulin glargine.

Insulin glargine 100 units/ml (Gla-100) has become a standard of care in diabetes treatment over the past decade, providing 24-h basal insulin coverage after once-daily subcutaneous injection for many people with diabetes, with a well-established efficacy and safety profile. New insulin glargine 300 units/ml (Gla-300) is a basal insulin that provides the same number of units as Gla-100 in a third of the volume. Compared with Gla-100, Gla-300 has shown more constant and prolonged pharmacokinetic (PK)/pharmacodynamic (PD) profiles. This review summarizes the findings from the EDITION series of clinical trials that investigated Gla-300 in individuals with type 1 and type 2 diabetes mellitus. Overall, Gla-300 has been shown to achieve similar glycaemic control with less, or similar, nocturnal hypoglycaemia compared with Gla-100, and a trend towards lower hypoglycaemia at any time of day. The EDITION series of clinical trials also provides some evidence for less weight gain with Gla-300 than with Gla-100. In addition, the PK/PD profiles of Gla-300 may allow more flexibility in the timing of doses, improving convenience; thus, Gla-300 could offer several positive features for individuals with diabetes requiring basal insulin therapy.

Impact of diabetes duration on hypoglycaemia in patients with type 2 diabetes treated with insulin glargine or NPH insulin.

AIM: To compare the impact of diabetes duration on hypoglycaemia in patients with type 2 diabetes mellitus (T2DM) treated with insulin glargine or NPH insulin. METHODS: A pooled analysis of 24-week patient level data from randomized controlled studies comparing once-daily insulin glargine with once-daily NPH insulin in insulin-naïve adult patients with T2DM was performed, stratifying patients into quartiles by duration of diabetes: <5.8 years; 5.8 to <9.2 years; 9.2 to <14 years and ≥14 years. Daytime and nocturnal hypoglycaemia events were evaluated. RESULTS: Data from 2330 patients in four randomized controlled trials were included in the analysis; 1258 treated with insulin glargine and 1072 with NPH insulin. The rates of daytime hypoglycaemia were similar for insulin glargine and NPH insulin, irrespective of disease duration. Patients with longer T2DM duration treated with glargine experienced greater glycated haemoglobin A1c (HbA1c) reductions. Rates of severe nocturnal hypoglycaemia and nocturnal hypoglycaemia [self-monitored blood glucose < 70 mg/dl (3.89 mmol/l) and < 50 mg/dl (2.78 mmol/l)] were all significantly and positively correlated with the duration of diabetes for patients treated with NPH insulin but not with insulin glargine. Despite improvements in HbA1c, rates of symptomatic nocturnal hypoglycaemia were significantly lower with insulin glargine than with NPH insulin in patients with longer T2DM duration. CONCLUSION: There is a lower risk for nocturnal hypoglycaemia with insulin glargine than with NPH insulin. When considering diabetes duration, insulin glargine (compared to NPH insulin) may be particularly beneficial in patients with a longer duration of T2DM.

Optimum management of type 2 diabetes--timely introduction, optimization and intensification of basal insulin.

The natural progression of type 2 diabetes mellitus (T2DM) requires continuing medical care, early insulin intensification and patient self-management education to reduce the risk of long-term complications, including microvascular and macrovascular complications. However, too few people are on insulin, and all too commonly have poor glycaemic control. This paradigm significantly increases the risk for long-term complications. It is becoming increasingly apparent that the early introduction of basal insulin, such as insulin glargine, is essential to provide clinically important improvements in glycaemic control. In this review, we discuss the rationale for the earlier insulinization in T2DM in order to reach and maintain treatment targets and to provide further support for the recent American Diabetes Association and European Association for the Study of Diabetes consensus statement.

Beyond insulin replacement: addressing the additional needs of the diabetes patient.

The management of type 2 diabetes mellitus (T2DM) typically focuses on correcting dysglycaemia to reduce risk for microvascular and macrovascular complications, possibly by reducing glucose-mediated oxidative stress. However, other cardiometabolic risk factors, including abdominal obesity and dyslipidaemia are often overlooked in the quest for perfect glucose control. The currently used antidiabetic agents, including insulin, metformin, sulphonylureas and thiazolidinediones, have limited efficacy on these risk factors. A number of new therapeutic agents are undergoing clinical development, including glucagon-like peptide 1 mimetics (exenatide and liraglutide) and dipeptidyl peptidase 4 inhibitors (sitagliptin and vildagliptin), which target the incretin system, and the cannabinoid-1 receptor antagonists (rimonabant), which target the endocannabinoid system, may hold some promise for meeting these unmet needs. In this review, the clinical properties of these agents and potential treatment pathways to best use these agents are discussed for improving the management of T2DM and cardiovascular risk.

Effect on glycemic control of the addition of 2.5 mg glipizide GITS to metformin in patients with T2DM.

AIMS: This study evaluated the effects on glycemic control of the addition of 2.5 mg glipizide GITS to metformin in patients with mild-to-moderate, but suboptimally controlled type 2 diabetes. METHODS: In this multicenter, double-blind, placebo-controlled study, 122 patients with type 2 diabetes inadequately controlled (A1c 7-8.5%) on metformin (> or =1000 mg/day for > or =3 months) were randomized to 16 weeks treatment with 2.5 mg/day glipizide GITS (n=61) or placebo (n=61), in addition to their current metformin dose. The primary efficacy variable was the change in A1c from baseline to endpoint. Changes in fasting plasma glucose (FPG), insulin concentrations, lipid profile and safety variables were also measured. RESULTS: The addition of glipizide GITS to metformin gave significantly greater improvements in mean A1c and FPG from baseline to endpoint than placebo addition (p<0.0002). Significantly more patients in the glipizide GITS group than in the placebo group achieved the target A1c level of A1c<7.0% (p<0.0001) and an A1c<6.5% (p<0.0033). Fasting insulin concentrations were similar in both groups and unchanged by treatment. Addition of glipizide GITS to metformin did not produce any significant or clinically relevant weight gain or changes in BMI. Both treatment regimens were well tolerated. CONCLUSIONS: This study showed that the addition of 2.5 mg glipizide GITS to metformin significantly improved glucose control in patients with type 2 diabetes inadequately controlled by metformin monotherapy.

Patient compliance and persistence with anti-hyperglycemic therapy: evaluation of a population of type 2 diabetic patients.

The persistence and compliance of type 2 diabetic patients to different regimens of anti-hyperglycemic therapy were assessed retrospectively. The pharmacy claims from a pharmacy benefit management organization were analysed from the third quarter of 1996 to the fourth quarter of 1999. Of the 23,400 patients enrolled and initiating anti-diabetic therapy, 85% started treatment with monotherapy, 9.5% with insulin alone, 4.1% with polytherapy and 1.3% with insulin plus another therapy. Monotherapy patients were characterized as receiving metformin, sulfonylurea or another agent. For the 1-year follow-up period, 70.5% of the metformin patients, 75.3% of the sulfonylurea patients and 86.8% of the polytherapy patients underwent no regimen modification (except discontinuation). For the patients who had no modification of their medication regimen, persistence with sulfonylurea or metformin monotherapy was 65% greater than with polytherapy over a 1-year period. Compliance with sulfonylurea or metformin monotherapy was 45% greater than with polytherapy.

Patient compliance and persistence with antihyperglycemic drug regimens: evaluation of a medicaid patient population with type 2 diabetes mellitus.

BACKGROUND: Drug use patterns among patients with type 2 diabetes mellitus have been studied in the general population but not specifically in the Medicaid population. OBJECTIVE: The purpose of this study was to examine antihyperglycemic drug use patterns among Medicaid recipients with type 2 diabetes and assess patients' persistence and compliance with different antihyperglycemic drug regimens. METHODS: Pharmaceutical claims data from Medi-Cal for January 1996 through September 1998 were analyzed to investigate antihyperglycemic drug use patterns over a 1-year and 2-year period. Prescription refill data were examined to assess patient compliance and persistence. RESULTS: Of the 37,431 patients in the 1-year follow-up cohort, 79.6% started antihyperglycemic treatment with monotherapy (ie, drug therapy with a single class of antihyperglycemic medication), 14.5% with insulin alone, 3.9% with polytherapy (ie, drug therapy with > or = 2 classes of medication other than insulin), and 2.1% with insulin plus another therapy. Of the patients receiving monotherapy, 85.3% were taking a sulfonylurea, 14.0% were taking metformin, and 0.7% were taking another agent. In the 1-year follow-up, 55.5% of patients taking metformin alone, 67.2% of those taking sulfonylurea alone, and 83.9% of those taking metformin plus sulfonylurea (M + S) did not undergo any modification of their regimen (except discontinuation of therapy). Among these patients, those taking metformin or sulfonylurea alone had approximately 65% more days of continuous (or persistent) treatment (129 and 128 days, respectively) per patient per year than did patients taking polytherapy (78 days). In addition, sulfonylurea or metformin monotherapy was associated with a 36% higher compliance rate than M + S polytherapy (177 days vs 130 days). CONCLUSION: Simple 1-drug antihyperglycemic regimens were associated with better compliance and persistence (as measured by prescription refill data) than more complex multiple-drug regimens among patients with type 2 diabetes in the Medi-Cal population.

Effects of pulsatile intravenous insulin therapy on the progression of diabetic nephropathy.

The purpose of this study was to assess the effects of pulsatile intravenous insulin therapy (PIVIT) on the progression of diabetic nephropathy in patients with type 1 diabetes mellitus (DM). This 18-month multicenter, prospective, controlled study involved 49 type 1 DM patients with nephropathy who were following the Diabetes Control and Complications Trial (DCCT) intensive therapy (IT) regimen. Of these, 26 patients formed the control group (C), which continued on IT, while 23 patients formed the treatment group (T) and underwent, in addition to IT, weekly PIVIT. Blood pressure in all patients was maintained below 140/90 mm Hg on antihypertensive medication, preferentially using angiotensin-converting enzyme (ACE) inhibitors. All study patients were seen in the clinic weekly for 18 months, had monthly glycohemoglobin (HbA1c), and every 3 months, 24-hour urinary protein excretion and creatinine clearance (CrCl) determinations. The HbA1c levels declined from 8.61% +/- 0.33% to 7.68% +/- 0.31% (P = .0028) in the T group and from 9.13% +/- 0.36% to 8.19% +/- 0.33% (P = .0015) in the C group during the study period. CrCl declined significantly in both groups, as expected, but the rate of CrCl decline in the T group (2.21 +/- 1.62 mL/min/yr) was significantly less than in the C group (7.69 +/- 1.88 mL/min/yr, P = .0343). We conclude that when PIVIT is added to IT in type 1 DM patients with overt nephropathy, it appears to markedly reduce the progression of diabetic nephropathy. The effect appears independent of ACE inhibitor therapy, blood pressure, or glycemic control.

Repaglinide in type 2 diabetes: a 24-week, fixed-dose efficacy and safety study.

In this 24-week multicenter, double-blind, randomized, fixed-dose trial, 361 patients having type 2 diabetes received daily preprandial treatment with placebo (n = 75), repaglinide 1 mg (n = 140), or repaglinide 4 mg (n = 146). By a last-observation carried-forward calculation, repaglinide 1 mg or 4 mg treatment decreased mean fasting plasma glucose (FPG) values (by -47 mg/dL or -49 mg/dL) while the placebo group had increased FPG values (by 19 mg/dL). For the repaglinide treatment groups at the end of the study, changes in HbA1c from baseline values ranged from 1.8 to 1.9 percentage points lower than the placebo group. There were no events of severe hypoglycemia. Nearly all hypoglycemic symptom episodes had blood glucose levels above 45 mg/dL. Repaglinide was well tolerated in a preprandial fixed-dose regimen of 1 mg or 4 mg, assigned without adjustment for clinical parameters.

Regulation of gluconeogenesis by glutamine in normal postabsorptive humans.

There is evidence that glutamine may act as a regulator of protein, free fatty acid, and glycogen metabolism. To test the hypothesis that glutamine may act as a physiological regulator of gluconeogenesis, we infused 16 normal postabsorptive volunteers with glutamine at a rate (11.4 micromol kg(-1) x min(-1)) estimated to approximate its appearance in plasma after a protein meal and assessed changes in production of glucose from glutamine, systemic glucose appearance and disposal, and uptake and release of glucose, glutamine, and alanine by forearm skeletal muscle. Although infusion of glutamine increased plasma glutamine concentration and turnover only threefold (from 0.63 +/- 0.03 to 1.95 +/- 0.10 mmol/l and from 5.43 +/- 0.24 to 14.85 +/- 0.66 micromol x kg(-1) x min(-1), respectively; P < 0.001), formation of glucose from glutamine increased sevenfold from 0.55 +/- 0.03 to 3.74 +/- 0.28 micromol x kg(-1) x min(-1) (P < 0.001). Formation of glucose from alanine was also stimulated (0.52 +/- 0.05 vs. 0.75 +/- 0.04 micromol x kg(-1) x min(-1); P < 0.001) in the absence of a change in plasma alanine concentration. Furthermore, glutamine infusion decreased its own de novo synthesis (4.55 +/- 0.22 vs. 2.81 +/- 0.62 micromol x kg(-1) x min(-1);P < 0.02) while increasing that of alanine (2.82 +/- 0.32 vs. 3.56 +/- 0.32 micromol x kg(-1) x min(-1); P < 0.002). Systemic glucose appearance, systemic glucose disposal, and forearm balance of glucose and alanine were not altered. Because the stimulatory effects of glutamine on gluconeogenesis occurred in the absence of changes in plasma insulin and glucagon levels, these results provide evidence that, in humans, glutamine may act both as a substrate and as a regulator of gluconeogenesis as well as a modulator of its own metabolism.

Glutamine and alanine metabolism in NIDDM.

Gluconeogenesis is increased in NIDDM. We therefore examined the metabolism of glutamine and alanine, the most important gluconeogenic amino acids, in 14 postabsorptive NIDDM subjects and 18 nondiabetic volunteers using a combination of isotopic ([6-3H]glucose (20 microCi, 0.2 microCi/min), [U-14C]glutamine (20 microCi, 0.2 microCi/min), [3-13C]alanine (99% 13C, 2 mmol, 20 micromol/min), [ring-2H5]phenylalanine (99% 2H, 2 micromol/kg, 0.03 micromol x kg(-1) x min(-1)), and limb balance techniques. Alanine turnover (4.54 +/- 0.24 vs. 5.64 +/- 0.33 micromol x kg(-1) x min(-1)), de novo synthesis (3.00 +/- 0.25 vs. 4.01 +/- 0.33 micromol x kg(-1) x min(-1)), and conversion to glucose (1.02 +/- 0.09 vs. 1.56 +/- 0.17 micromol x kg(-1) x min(-1)) were increased in NIDDM subjects (all P < 0.01), while its forearm release (0.45 +/- 0.04 vs. 0.39 +/- 0.04 micromol x kg(-1) x min(-1)) was unaltered. Although glutamine turnover (4.81 +/- 0.23 vs. 4.40 +/- 0.31 micromol x kg(-1) x min(-1)) was unaltered in NIDDM, its conversion to glucose (0.57 +/- 0.04 vs. 1.08 +/- 0.10 micromol x kg(-1) x min(-1)) and to alanine (0.10 +/- 0.01 vs. 0.34 +/- 0.04 micromol x kg(-1) x min(-1)) (both P = 0.001) was increased while its oxidation (2.84 +/- 0.27 vs. 1.84 +/- 0.15 micromol x kg(-1) x min(-1), P = 0.03) and forearm release (0.77 +/- 0.05 vs. 0.62 +/- 0.09 micromol x kg(-1) x min(-1), P < 0.008) were both reduced. Our results thus demonstrate that there are substantial alterations of glutamine and alanine metabolism in NIDDM. Conversion of both amino acids to glucose and the proportion of their turnover used for gluconeogenesis are increased; release of both amino acids from tissues other than skeletal muscle seems to be increased. Finally, the reduction in glutamine oxidation, possibly the result of competition with glucose and free fatty acids as fuels, makes more glutamine available for gluconeogenesis without a change in its turnover.

Green fluorescent protein and its derivatives as versatile markers for gene expression in living Drosophila melanogaster, plant and mammalian cells.

We have investigated the utility of the green fluorescent protein (GFP) as a marker for gene expression in living adult Drosophila melanogaster (Dm) and cultured plant and mammalian cells. Using Dm, we generated transgenic flies bearing a glass-responsive gfp fusion gene to test the utility of GFP as a spatial reporter. In the adult living fly, GFP is clearly visible in the ocelli and the eye. We have optimized the use of filters for distinguishing the GFP signal from abundant autofluorescence in living Dm. In addition, we have used GFP to identify photoreceptor cells in pupal eye cultures that have been fixed and stained according to standard histological procedures. GFP was also detected in individual living plant cells following transient transfection of soybean suspension cultures, demonstrating that GFP is an effective transformation marker in plant cells. Similarly, transient transfection of mammalian cells with a modified form of GFP, S65T, allowed detection of single living cells expressing the reporter. This modified form of GFP gave a robust signal that was resistant to photobleaching. We then used a CellScan system exhaustive photon reassignment (EPR) deconvolution algorithm to generate high-resolution three-dimensional images of GFP fluorescence in the living cell.

Estimation of glucose-alanine-lactate-glutamine cycles in postabsorptive humans: role of skeletal muscle.

To evaluate transfer of carbon between plasma glucose and plasma alanine (glucose-alanine cycle) and lactate (Cori cycle), to assess the contribution of skeletal muscle to these cycles, and to determine whether a glucose-glutamine cycle exists in postabsorptive humans, we infused 11 normal overnight-fasted volunteers with [2-3H]glucose, [6-14C]glucose, and [3-13C]alanine to isotopic steady state and in 7 of these simultaneously measured forearm net balance, uptake, and release of labeled and unlabeled glucose, lactate, and alanine. We found that 40.9 +/- 3.3, 66.8 +/- 3.2, and 13.4 +/- 1.1%, respectively, of plasma alanine, lactate, and glutamine carbon came from plasma glucose. More plasma glucose was converted to plasma alanine than could be derived from plasma alanine (1.89 +/- 0.20 vs. 1.48 +/- 0.15 mumol.kg-1.min-1, P < 0.001). A similar direction of net carbon flux was found for lactate (8.5 vs. 4.2 mumol.kg-1.min-1), with only glutamine adding more carbon to plasma glucose than was received from it (1.0 vs. 0.75 mumol.kg-1.min-1). Skeletal muscle accounted for 50.2 +/- 3.9 and 45.5 +/- 5.7% of the overall appearance of alanine and lactate in plasma and 54.2 +/- 5.4 and 36.4 +/- 4.2% of their respective origins from plasma glucose. Skeletal muscle release of alanine and lactate that had been formed from plasma glucose accounted for 19.1 +/- 2.1 and 48.4 +/- 4.8%, respectively, of muscle glucose uptake and 42.4 +/- 5.5 and 49.9 +/- 5.8% of the overall release of alanine and lactate from muscle.(ABSTRACT TRUNCATED AT 250 WORDS)

Metabolic effects of metformin in non-insulin-dependent diabetes mellitus.

BACKGROUND: The metabolic effects and mechanism of action of metformin are still poorly understood, despite the fact that it has been used to treat patients with non-insulin-dependent diabetes mellitus (NIDDM) for more than 30 years. METHODS: In 10 obese patients with NIDDM, we used a combination of isotope dilution, indirect calorimetry, bioimpedance, and tissue-balance techniques to assess the effects of metformin on systemic lactate, glucose, and free-fatty-acid turnover; lactate oxidation and the conversion of lactate to glucose; skeletal-muscle glucose and lactate metabolism; body composition; and energy expenditure before and after four months of treatment. RESULTS: Metformin treatment decreased the mean (+/- SD) glycosylated hemoglobin value from 13.2 +/- 2.2 percent to 10.5 +/- 1.6 percent (P < 0.001) and reduced fasting plasma glucose concentrations from 220 +/- 41 to 155 +/- 28 mg per deciliter (12.2 +/- 0.7 to 8.6 +/- 0.5 mmol per liter) (P < 0.001). Although resting energy expenditure did not change, the patients lost 2.7 +/- 1.3 kg of weight (P < 0.001), 88 percent of which was adipose tissue. The mean (+/- SE) rate of plasma glucose turnover (hepatic glucose output and systemic glucose disposal) decreased from 2.8 +/- 0.2 to 2.0 +/- 0.2 mg per kilogram of body weight per minute (15.3 +/- 0.9 to 10.8 +/- 0.9 mumol per kilogram per minute) (P < 0.001), as a result of a decrease in hepatic glucose output; systemic glucose clearance did not change. The rate of conversion of lactate to glucose (gluconeogenesis) decreased by 37 percent (P < 0.001), whereas lactate oxidation increased by 25 percent (P < 0.001). There were no changes in the plasma lactate concentration, plasma lactate turnover, muscle lactate release, plasma free-fatty-acid turnover, or uptake of glucose by muscle. CONCLUSIONS: Metformin acts primarily by decreasing hepatic glucose output, largely by inhibiting gluconeogenesis. It also seems to induce weight loss, preferentially involving adipose tissue.

Pancreatic beta-cell dysfunction as the primary genetic lesion in NIDDM. Evidence from studies in normal glucose-tolerant individuals with a first-degree NIDDM relative.

OBJECTIVE: To test the hypothesis that insulin resistance precedes impaired insulin secretion in individuals genetically predisposed to non-insulin-dependent diabetes mellitus (NIDDM). DESIGN: Case-control study. SETTING: Outpatient facility of clinical research center. PARTICIPANTS: One hundred volunteers of European ancestry having normal glucose tolerance, 50 with and 50 without a first-degree NIDDM relative, matched for age, sex, and degree of obesity. MAIN OUTCOME MEASURES: Insulin secretion and insulin sensitivity assessed by hyperglycemic (N = 100) and euglycemic-hyperinsulinemic (N = 62) clamp experiments. RESULTS: The individuals with a first-degree NIDDM relative had reduced first- and second-phase insulin responses (mean +/- SEM, 939 +/- 68 vs 1209 +/- 82 pmol/L, and 322 +/- 19 vs 407 +/- 24 pmol/L, respectively, P = .001 and .01), but their insulin sensitivity (148 +/- 6 and 92 +/- 6 nmol.kg-1.min-1/pmol.L-1 in hyperglycemic and euglycemic clamp studies) did not differ from that of the control group (126 +/- 5 and 81 +/- 7 nmol.kg-1.min-1/pmol.L-1, in hyperglycemic and euglycemic clamp studies, P = .07 and .24, respectively). In some individuals only first- or only second-phase insulin responses were reduced. CONCLUSION: In this study population, heterogeneous defects in insulin secretion were demonstrated, while defects in insulin sensitivity were not evident. We therefore conclude that since the earliest defects identified in a group genetically at high risk to develop NIDDM are those related to insulin secretion, defects in insulin secretion rather than insulin sensitivity are likely the major genetic factor predisposing to development of NIDDM.

Glutamine: a major gluconeogenic precursor and vehicle for interorgan carbon transport in man.

To compare glutamine and alanine as gluconeogenic precursors, we simultaneously measured their systemic turnovers, clearances, and incorporation into plasma glucose, their skeletal muscle uptake and release, and the proportion of their appearance in plasma directly due to their release from protein in postabsorptive normal volunteers. We infused the volunteers with [U-14C] glutamine, [3-13C] alanine, [2H5] phenylalanine, and [6-3H] glucose to isotopic steady state and used the forearm balance technique. We found that glutamine appearance in plasma exceeded that of alanine (5.76 +/- 0.26 vs. 4.40 +/- 0.33 mumol.kg-1.min-1, P < 0.001), while alanine clearance exceeded glutamine clearance (14.7 +/- 1.3 vs. 9.3 +/- 0.8 ml.kg-1.min-1, P < 0.001). Glutamine appearance in plasma directly due to its release from protein was more than double that of alanine (2.45 +/- 0.25 vs. 1.16 +/- 0.12 mumol.kg-1.min-1, P < 0.001). Although overall carbon transfer to glucose from glutamine and alanine was comparable (3.53 +/- 0.24 vs 3.47 +/- 0.32 atoms.kg-1.min-1), nearly twice as much glucose carbon came from protein derived glutamine than alanine (1.48 +/- 0.15 vs 0.88 +/- 0.09 atoms.kg-1.min-1, P < 0.01). Finally, forearm muscle released more glutamine than alanine (0.88 +/- 0.05 vs 0.48 +/- 0.05 mumol.100 ml-1.min-1, P < 0.01). We conclude that in postabsorptive humans glutamine is quantitatively more important than alanine for transporting protein-derived carbon through plasma and adding these carbons to the glucose pool.

Distribution of NOS in normoxic vs. hypoxic rat lung: upregulation of NOS by chronic hypoxia.

Expression and localization of nitric oxide synthase (NOS) in the lungs of chronically hypoxic and normoxic rats were studied using both immunohistochemistry and NADPH diaphorase (NADPH-d) staining techniques. In the normoxic and in the hypoxic rat, NOS was detected by both methods in the endothelium of large pulmonary vessels and in the epithelium of bronchi and bronchioli. NOS expression was not detected in the endothelium of normoxic pulmonary resistance vessels but was prominently expressed in the endothelium of these vessels after 2-4 wk of chronic hypoxia. In contrast to small pulmonary vessels, the endothelium of small bronchial vessels exhibited NOS immunostaining in both normoxic and hypoxic lungs. Hypoxia was also found to induce de novo NOS expression in the smooth muscle of large and small pulmonary vessels and in bronchial smooth muscle. NOS enzyme activity in lung homogenates was assessed by [3H]arginine to [3H]citrulline conversion. The activity of soluble NOS, but not particulate NOS, was increased in the hypoxic lungs. These results demonstrate chronic hypoxia-induced upregulation of NOS protein expression and activity in the rat lung, suggesting a potentially important role of nitric oxide in adaptation of the pulmonary circulation to chronic hypoxia. The lack of immunostaining in small pulmonary resistance vessels is also consistent with physiological studies suggesting that NO may not be involved in the mechanism for maintaining the normally low pulmonary vascular resistance.

Do estrogens improve bone mineral density in osteoporotic women over age 65?

A retrospective analysis of our experience with estrogen and fluoride treatment in 91 patients with postmenopausal osteopenia followed for 6-47 months has been performed. Treatment included calcium (1000 mg/day) and either conjugated estrogens (0.625 mg/day) or sodium fluoride (50 mg/day), or both. All patients had at least two serial dual-photon spinal bone mineral density measurements performed 6 months or more apart. Estrogen treatment was associated with increased bone mineral density (5.3%/year), as was fluoride alone (7.5%/year). Estrogen and fluoride together were additive (9.6%/year). In women over age 65 the estrogen effect was just as great (6.9%/year) as in younger women. Estrogen benefit occurred predominantly in the first 18 months of treatment (7.0%/year), after which time changes in bone mineral density were similar to those in untreated controls, who showed stable bone mineral density. We conclude that aggressive estrogen and fluoride treatment tailored to the severity of the individual's postmenopausal osteopenia results in short-term improvement in spinal bone mineral density. These data further support that elderly women respond to estrogen replacement therapy with absolute and relative increments in bone density similar to those in younger women.