Response of soybean in cyst nematode-infested soils at three soil water regimes

Large pot (2 years) and field experiments (1 year) were conducted to determine the response of susceptible soybean Glycine max (L.) Merr. cultivars (Essex and Hutcheson) grown in soybean-cyst-nematode (SCN), Heterodera glycines-infested soils at three soil water regimes. The soil water regimes were irrigation whenever soil water potential ([psi]s) 0.30-m deep was i) -30 kPa (I-30) or ii) - 50 kPa (I-50), and iii) no irrigation. Cyst nematode levels in the pot experiment were either 0 or 20,000 second-stage juveniles (J2) per pot. The field experiment was conducted on soil naturally infested with a population of 145 to 475 cysts L(1) of soil. All growth parameters studied were drastically affected in the presence of SCN under nonirrigated conditions for the large pot tests; however, SCN did not influence growth parameters in the field experiment. Seed yield was lowest in the no irrigation treatment when all treatments were compared in both the pot and field experiments. The infested no irrigation treatment in the pot experiment had the lowest yield among soil water treatments.

The impact of metformin therapy on hepatic glucose production and skeletal muscle glycogen synthase activity in overweight type II diabetic patients

The effect of metformin therapy on glucose metabolism was examined in eight overweight newly presenting untreated type II diabetic patients (five males, three females). Patients were treated for 12 weeks with either metformin (850 mg x 3) or matching placebo using a double-blind crossover study design; patients were studied at presentation and at the end of each treatment period. Insulin action was assessed by measuring activation of skeletal muscle glycogen synthase (GS) before and during a 4-hour hyperinsulinemic euglycemic clamp (100 mU.kg-1 x h-1). Metformin therapy was associated with a significant decrease in fasting blood glucose (6.8 +/- 0.6 v 8.3 +/- 0.9 mmol.L-1, P < .01) and glycosylated hemoglobin ([HbA1] 7.7% +/- 0.4% v 8.5% +/- 0.5%, P < .01) levels. Fasting hepatic glucose production (HGP) was also significantly decreased following metformin therapy (1.98 +/- 0.13 v 2.41 +/- 0.20 mg.kg-1 x min-1, P < .02), whereas fasting insulin and C-peptide concentrations remained unaltered. The decrease in basal HGP correlated closely with the decrease in fasting blood glucose concentration (r = .92, P < .001). Insulin-stimulated glucose uptake was assessed using the hyperinsulinemic euglycemic clamp technique and was increased post-metformin (3.8 +/- 0.6 v 3.1 +/- 0.7 mg.kg-1 x min-1, P < .05). This was primarily the result of increased nonoxidative glucose metabolism (1.1 +/- 0.6 v 0.4 +/- 0.6 mg.kg-1 x min-1, P < .05); oxidative glucose metabolism did not change. Metformin had no measurable effect on insulin activation of skeletal muscle GS, the rate-limiting enzyme controlling muscle glucose storage.(ABSTRACT TRUNCATED AT 250 WORDS)

Location of Heterodera glycines-induced Syncytia in Soybean as Affected by Soil Water Regimes

Locations of syncytia induced by the soybean cyst nematode (SCN), Heterodera glycines race 3, were compared in roots of 'Essex', a susceptible soybean (Glycine max (L.) Merr.) cultivar, at three soil water regimes. The plants were grown in wet (-5 to -20 kPa), moderately wet (-30 to -50 kPa), and moderately dry (-60 to -80kPa) autoclaved Captina silt loam soil (Typic Fragiudult). In the moderately dry soil, syncytia were found only in the stele, but in moderately wet and wet soils, syncytia occurred primarily in the cortex and occasionally in the stele. The location of syncytia in the cortical tissue of roots growing in wet and moderately wet soils may account for the tolerance of susceptible soybean cultivars grown under well-irrigated conditions where there is less interference with water transport through roots. Cell-wall perforations and dense cytoplasm were characteristic of syncytial cells observed in root tissues of all treatments.

Abnormal activation of glycogen synthesis in fibroblasts from NIDDM subjects. Evidence for an abnormality specific to glucose metabolism

To determine whether the tendency for NIDDM to run in families could relate to genetically determined defects in insulin stimulation of glycogen synthesis, skin fibroblasts from subjects with a strong family history of NIDDM were studied. Fibroblasts from nondiabetic subjects without any family history of NIDDM were studied as control subjects. The cells were studied after 7-16 passages in culture. Rates of glycogen synthesis were lower in fibroblasts from NIDDM subjects both basally and with maximal insulin stimulation (0.77 +/- 0.11 vs. 0.46 +/- 0.04 pmol.well-1 x h-1 [P < 0.02] and 1.49 +/- 0.26 vs. 0.69 +/- 0.05 pmol.well-1 x h-1 +adP < 0.01]). Rates of glycogen synthesis were stimulated 1.9 +/- 0.2-fold above basal in the control cells and 1.5 +/- 0.1-fold above basal in the NIDDM cells (P < 0.02). Rates of [3H]thymidine uptake were similar in control and NIDDM fibroblasts (basal, 28.3 +/- 2.8 vs. 39.2 +/- 8.0; maximum, 50.9 +/- 7.2 vs. 69.3 +/- 16.9 dpm x 10(-3), respectively). Rates of uptake increased similarly in control and NIDDM cells by 1.8 +/- 0.1- and 1.7 +/- 0.1-fold above basal. Maximum specific fibroblast insulin binding was similar for control and NIDDM subjects (194.0 +/- 29.2 vs. 176.1 +/- 24.9 fmol 125I-labeled insulin bound/mg protein respectively). The tyrosine kinase activity of insulin receptors isolated from the control and NIDDM fibroblasts was similar (basal, 135 +/- 30 vs. 149 +/- 33; submaximal, 153 +/- 28 vs. 155 +/- 30; and maximal insulin, 191 +/- 45 vs. 213 +/- 48 dpm.mg protein-1 x min-1).(ABSTRACT TRUNCATED AT 250 WORDS)

Discriminative stimulus properties of cocaine, alone and in combination with buprenorphine, morphine and naltrexone

Rats were trained to discriminate a dose of 10.0 mg/kg cocaine from saline. During substitution tests, both cocaine (5.6-10.0 mg/kg) and d-amphetamine (1.0-3.0 mg/kg) produced greater than 80% responding on the cocaine-appropriate level. In contrast, buprenorphine (0.03-0.56 mg/kg), morphine (0.3-10.0 mg/kg) and naltrexone (1.0-10.0 mg/kg) failed to substitute for the cocaine stimulus, up to doses that substantially decreased rate of responding. When the cocaine dose-effect curve was redetermined in the presence of selected doses of buprenorphine, the amount of cocaine-appropriate responding following a low dose of cocaine (1.0 mg/kg) was increased slightly whereas cocaine-appropriate responding following higher doses of cocaine (3.0 and 5.6 mg/kg) was reduced slightly. Responding following the training dose of cocaine (10.0 mg/kg) was not changed. These results indicate that buprenorphine produced only small alterations in cocaine's discriminative stimulus effects and that the nature of these alterations differed depending on the dose of cocaine examined.

Loss of heterozygosity on chromosome 17p and mutant p53 in HPV-negative cervical carcinomas

Inactivation of the protein product of the wild-type tumour suppressor gene p53 through complexing of the protein with the E6 oncoprotein of human papillomaviruses (HPV) in HPV-infected cells is thought to be important in the aetiology of cervical carcinoma. Mutations of p53 have also been reported in HPV-negative carcinomas, and we now demonstrate loss of heterozygosity (LOH) of chromosome region 17p13 (in which p53 is located) in such tumours. Immunocytochemical staining with monoclonal antimutant-p53 antibody revealed that the carcinomas with LOH on 17p and completely lacking HPV DNA sequences had mutant p53. Thus the LOH had apparently resulted in the loss of the wild-type allele. Consequently, in both HPV-positive and HPV-negative tumours there is loss of function of wild-type p53, in the former because the protein product of the p53 gene complexes with that of the viral E6 gene, in the latter because the protein is altered, presumably as a result of a direct alteration of the p53 gene but possibly because of other post-translational changes. That this mutant allele of the tumour suppressor gene may sometimes behave like an oncogene is suggested by the presence of more than the expected number of copies of the remaining chromosome 17 homologue in some carcinomas.

Gliclazide: metabolic and vascular effects--a perspective

Gliclazide is a second-generation sulfonylurea that is widely used in the treatment of non-insulin-dependent diabetes mellitus (NIDDM). It has been recommended for use on the basis of both its metabolic and nonmetabolic effects. It has a clear beneficial effect on metabolic control in NIDDM. Blood glucose and lipid levels are lowered. The glucose-lowering effects are secondary to both enhanced insulin secretion and a decrease in insulin resistance. The former is due to closure of a K+ adenosine triphosphate (ATP) channel in the beta cell. The mechanism whereby insulin action on the liver and muscle are potentiated remains unknown. It does not appear to involve the insulin receptor, and although glycogen synthase activation is enhanced, this is probably not specific. It has proven difficult to separate the metabolic effects of gliclazide from the effects of improved control. The metabolic actions are probably also shared with other sulfonylureas. Gliclazide also has beneficial effects on platelet behavior and function and on the endothelium, in addition to improving free radical status. These effects should be beneficial for the prevention of diabetic microangiopathy and macroangiopathy. Some evidence has appeared for the prevention of deterioration of diabetic retinopathy, but results are variable and more convincing studies are required. Many of the nonmetabolic effects of gliclazide appear to be unique to this agent. Gliclazide thus appears to be a reasonable choice in the treatment of NIDDM with diet failure, both from the metabolic and nonmetabolic standpoint.

Effect of increased free fatty acid supply on glucose metabolism and skeletal muscle glycogen synthase activity in normal man

1. Experimental elevation of plasma non-esterified fatty acid concentrations has been postulated to decrease insulin-stimulated glucose oxidation and storage rates. Possible mechanisms were examined by measuring skeletal muscle glycogen synthase activity and muscle glycogen content before and during hyperinsulinaemia while fasting plasma non-esterified fatty acid levels were maintained. 2. Fasting plasma non-esterified fatty acid levels were maintained in seven healthy male subjects by infusion of 20% (w/v) Intralipid (1 ml/min) for 120 min before and during a 240 min hyperinsulinaemic euglycaemic clamp (100 m-units h-1 kg-1) combined with indirect calorimetry. On the control day, 0.154 mol/l NaCl was infused. Vastus lateralis muscle biopsy was performed before and at the end of the insulin infusion. 3. On the Intralipid study day serum triacylglycerol (2.24 +/- 0.20 versus 0.67 +/- 0.10 mmol/l), plasma nonesterified fatty acid (395 +/- 13 versus 51 +/- 1 mumol/l), blood glycerol (152 +/- 2 versus 11 +/- 1 mumol/l) and blood 3-hydroxybutyrate clamp levels [mean (95% confidence interval)] [81 (64-104) versus 4 (3-5) mumol/l] were all significantly higher (all P less than 0.001) than on the control study day. Lipid oxidation rates were also elevated (1.07 +/- 0.07 versus 0.27 +/- 0.08 mg min-1 kg-1, P less than 0.001). During the clamp with Intralipid infusion, insulin-stimulated whole-body glucose disposal decreased by 28% (from 8.53 +/- 0.77 to 6.17 +/- 0.71 mg min-1 kg-1, P less than 0.005).(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of intravenous metformin on glucose metabolism during hyperglycaemia in type 2 diabetes

A stepped intravenous metformin infusion was used in conjunction with the hyperglycaemic clamp technique to study the dose-response relationship of plasma metformin concentration with hepatic glucose production and peripheral glucose disposal in nine patients with Type 2 diabetes. The study was of double-blind crossover design, using NaCl infusion as control. Plasma metformin concentrations spanning the therapeutic range (1.64 +/- 0.13 mg l-1 and 6.57 +/- 0.61 mg l-1) were achieved. No differences in peripheral glucose disposal were demonstrated when compared with NaCl infusion (3.4 +/- 0.1 vs 3.6 +/- 0.2 (+/- SE) mg kg-1 min-1 and 3.4 +/- 0.2 vs 3.3 +/- 0.2 mg kg-1 min-1, respectively). There was also no difference in basal hepatic glucose production during metformin and NaCl infusion (2.7 +/- 0.3 vs 2.8 +/- 0.2 mg kg-1 min-1). No acute effect of metformin on hepatic glucose production or peripheral glucose disposal was observed, implying that a chronic persistent effect is more important in these respects than immediate effects consequent upon changes in plasma drug level.

The effect of sulphonylurea therapy on skeletal muscle glycogen synthase activity and insulin secretion in newly presenting type 2 (non-insulin-dependent) diabetic patients

Ten newly presenting, Type 2 (non-insulin-dependent), Caucasian diabetic patients were studied before and after 8 weeks treatment with the sulphonylurea gliclazide, and in parallel 13 similar patients were studied before and after 8 weeks treatment with diet alone. Eight non-diabetic subjects were also studied. Insulin action was assessed by measuring activation of skeletal muscle glycogen synthase (GS) prior to and during a 4-h hyperinsulinaemic euglycaemic clamp (100 mU kg-1 h-1). Fasting plasma glucose (+/- SE) and glycosylated haemoglobin decreased to a greater extent in the gliclazide treated patients (fall of 6.2 +/- 0.7 vs 2.1 +/- 0.5 mmol l-1, p less than 0.005 and 4.7 +/- 0.5 vs 2.1 +/- 0.5%, p less than 0.005). This was accompanied by an increase in fasting serum insulin concentrations in the gliclazide treated patients (7.0 +/- 1.3 to 10.1 +/- 1.1 mU l-1, p less than 0.005), but no change in the diet treated patients. Fractional GS activity did not increase during the clamp at presentation in either treatment group (change +2.9 +/- 1.8 and -1.5 +/- 1.9%, respectively) whereas it increased markedly in the control subjects (+16.4 +/- 3.4%, both p less than 0.001). After 8-week treatment there was a significant increase in GS activity during the clamp in the patients receiving gliclazide (+6.9 +/- 2.7%, p less than 0.05), but no change in GS activity in the patients on diet alone (+0.5 +/- 1.4%). The difference in post-treatment muscle insulin action was significant (p less than 0.05). There was no correlation between the degree of improvement in metabolic control and the improvement in response of GS to insulin in the gliclazide treated patients (r = -0.06), suggesting a possible direct drug effect on skeletal muscle. Glucose requirement during the clamp at presentation was markedly lower in both treatment groups than in the non-diabetic subjects (gliclazide 2.1 +/- 0.3, diet 2.0 +/- 0.6 vs 7.8 +/- 0.4 mg kg-1 min-1, both p less than 0.001), and despite a marked improvement in both groups after treatment (4.3 +/- 0.4 and 3.1 +/- 0.5 mg kg-1 min-1, both p less than 0.001) remained lower than in the non-diabetic subjects (p less than 0.001).(ABSTRACT TRUNCATED AT 400 WORDS)

Impaired activation of skeletal muscle glycogen synthase in non-insulin-dependent diabetes mellitus is unrelated to the degree of obesity

Twenty-five newly presenting, untreated, white, non-insulin-dependent diabetic (NIDDM) subjects were studied within 72 hours of diagnosis. They were allocated to three groups according to their body mass index [BMI] (lean BMI less than 25.0, n = 9; overweight BMI 25.0 to 30.0, n = 6; obese BMI greater than .30.0 kg/m2, n = 10). All three groups exhibited equivalent hyperglycemia. Eleven normal control subjects were also studied. The degree of activation of skeletal muscle glycogen synthase (GS) was used as an intracellular marker of insulin action, before and during a 240-minute insulin infusion (100 mU/kg/h). Fractional GS activity did not increase in the lean (change, -0.9 +/- 3.3%), the overweight (-1.9 +/- 2.7%), or the obese (+2.2 +/- 1.6%) NIDDM subjects during the insulin infusion and was markedly decreased compared with the control subjects (change, +14.6 +/- 2.4%, all P less than .001). Glucose requirement was also significantly decreased in all three NIDDM groups (103 +/- 23 v 81 +/- 14 v 53 +/- 14 mg/m2/min, respectively) compared with the control subjects (319 +/- 18 mg/m2/min, all P less than .001). There was a significant negative correlation with BMI (r = -.51, P less than .01), but the difference in glucose requirement between the lean and obese NIDDM groups was not significant. Muscle GS activity at the end of the euglycemic clamp correlated with glucose requirement (r = .53, P less than .001), and a similar correlation was observed between the insulin-induced change in muscle GS activity from basal and glucose requirement (r = .47, P less than .005).(ABSTRACT TRUNCATED AT 250 WORDS)

The Mooney Problem Check List—A Standardization of the College Form

The Mooney Problem Check List, College Form, was administered to 2261 students from six Louisiana universities for standardization purposes. Usable protocols were obtained from 1929 subjects. Comparisons among schools, school classes, sex, race, and marital status were made for the 11 Mooney categories. Norm tables were developed for all groups with sufficient ns for the several categories. A component analysis was also done, with 13 components retained for rotation by varimax and promax. Comparisons among groups were made for the 11 categories and 13 factors. Tables of norms were likewise developed for sufficiently large groups.

Purification, characterization, and localization of aspartoacylase from bovine brain

Canavan disease, an autosomal recessive disorder, is characterized biochemically by N-acetylaspartic aciduria and aspartoacylase (N-acyl-L-aspartate amidohydrolase; EC 3.5.1.15) deficiency. However, the role of aspartoacylase and N-acetylaspartic acid in brain metabolism is unknown. Aspartoacylase has been purified to apparent homogeneity with a specific activity of approximately 19,000-20,000 nmol of aspartate released/mg of protein. The native enzyme is a 58-kDa monomer. The purified aspartoacylase activity is enhanced by divalent cations, nonionic detergents, and dithiothreitol. Low levels of dithiothreitol or beta-mercaptoethanol are required for enzyme stability. Aspartoacylase has a Km of 8.5 x 10(-4) M and a Vmax of 43,000 nmol/min/mg of protein. Inhibition of aspartoacylase by glycyl-L-aspartate and amino derivatives of D-aspartic acid suggests that the carbon backbone of the substrate is primarily involved in its interaction with the active site and that a blocked amino group is essential for the catalytic activity of aspartoacylase. Biochemical and immunocytochemical studies revealed that aspartoacylase is localized to white matter, whereas the N-acetylaspartic acid concentration is threefold higher in gray matter than in white matter. Our studies so far indicate that aspartoacylase is conserved across species during evolution and suggest a significant role for aspartoacylase and N-acetylaspartic acid in normal brain biology.

Morphology of palpably abnormal injection sites and effects on absorption of isophane(NPH) insulin

The absorption of isophane(NPH) insulin (Human Insulatard) from palpably abnormal thigh insulin injection sites was determined in 10 C-peptide negative diabetic patients. Absorption was compared with a control day study when the insulin was injected into normal thigh. Standard meals were given 30 and 240 min after the injection. Within 2 weeks the tissue morphology and adipose tissue depths at both injection sites were assessed by ultrasound scanning. Absorption of isophane(NPH) insulin was markedly defective from the abnormal compared with the normal injection sites (area under the free insulin curve to 10 h 115 +/- 15 vs 188 +/- 21 mU l-1 h; p less than 0.01). The area under the blood glucose curve from 270 min to the end of the study at 600 min was significantly greater after injection into the palpably abnormal injection site compared with normal thigh (80.4 +/- 5.2 vs 61.2 +/- 7.0 mmol l-1 h; p less than 0.05) representing a 22% improvement in blood glucose control on the normal injection site afternoon. The depth of abnormal injection site tissue was significantly greater than the depth of adipose tissue at the control site (17 +/- 6 vs 5 +/- 4 mm; p less than 0.001) and considerable disruption of the normal anatomy observed. These results demonstrate defective absorption of isophane(NPH) insulin from palpably abnormal injection sites and describe the morphology of the abnormal tissue.

Reactivation of latent melioidosis

Reports of melioidosis in residents of European countries are rare. We describe a case of reactivation of latent melioidosis in a United Kingdom resident. The case demonstrates the lack of clinical response to chemotherapy despite proven in vitro sensitivity of the organism to the drugs used. It is important to consider melioidosis as a cause of septicaemic illness in patients who have travelled to, or been resident in South-East Asia.

Different absorption of isophane (NPH) insulin from subcutaneous and intramuscular sites suggests a need to reassess recommended insulin injection technique

The absorption of isophane (NPH) insulin from subcutaneous and intramuscular injection sites was measured in seven healthy volunteers using the euglycaemic clamp technique. Human Insulatard (Nordisk, Gentofte, Denmark) was administered in a dose of 0.25 U kg-body-weight-1 into the anterior compartment of the thigh. In random order injections were given either subcutaneously, via 12 mm needle at 45 degrees to the skin into a skinfold, or intramuscularly by 25 mm needle perpendicularly to the skin. Insulin concentrations rose more rapidly after intramuscular injection than after subcutaneous injection, being significantly higher as early as 60 min after injection (19.7 +/- 1.6 (+/- SE) vs 8.7 +/- 1.4 mU l-1; p less than 0.001). Thereafter insulin concentrations remained significantly higher for the remaining 360 min of study, reflected by a significantly greater area under the insulin concentration curve for the 420 min study (IM 8630 +/- 1256 vs SC 4908 +/- 465 mU l-1 min, p less than 0.05). A significantly greater quantity of infused glucose was required to maintain euglycaemia after intramuscular injection than after subcutaneous injection (923 +/- 256 vs 216 +/- 71 mg kg-1 min, p less than 0.05). These results demonstrate a striking difference in the pharmacokinetics of an isophane (NPH) insulin when injected into subcutaneous fat and muscle.

Effects of intensive dietary treatment on insulin-stimulated skeletal muscle glycogen synthase activation and insulin secretion in newly presenting type 2 diabetic patients

Ten newly presenting, untreated, Europid Type 2 diabetic patients were studied before and after 8 weeks treatment with intensive diet alone. Nine normal control subjects were also studied. The degree of activation of skeletal muscle glycogen synthase (GS) was used as an intracellular marker of insulin action, prior to and during a 240-min insulin infusion (100 mU kg-1 h-1). Fasting blood glucose decreased from 12.1 +/- 0.9 (+/- SE) to 9.2 +/- 0.8 mmol l-1 (p less than 0.01), but there was no change in fasting insulin concentrations, 9.9 +/- 2.3 vs 9.3 +/- 2.1 mU l-1. Fractional GS activity did not increase in the Type 2 diabetic patients during the insulin infusion either at presentation (change -1.5 +/- 1.9%) or after treatment (change +0.9 +/- 1.8%), and was markedly decreased compared with the control subjects (change +14.5 +/- 2.8%, both p less than 0.001). Glucose requirement during the clamp was decreased in the Type 2 diabetic patients at presentation (2.2 +/- 0.7 vs 7.3 +/- 0.6 mg kg-1 min-1, p less than 0.001), and despite improvement following dietary treatment to 3.3 +/- 0.6 mg kg-1 min-1 (p less than 0.01) remained lower than in the control subjects (p less than 0.001). Fasting plasma non-esterified fatty acid (NEFA) concentrations were elevated at presentation (p less than 0.05), and failed to suppress normally during the insulin infusion. After treatment fasting NEFA concentrations decreased (p less than 0.05) and suppressed normally (p less than 0.05). Insulin secretion was assessed following an intravenous bolus of glucose (0.5 g kg-1) at euglycaemia before and after treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Ultrastructural immunogold labeling of glial filaments in osmicated and unosmicated epoxy-embedded tissue

On-grid (post-embedding) immunolabeling methods with epoxy resins have been difficult to apply to thin structures such as intermediate filaments, which may remain inaccessible within the plastic. In this study, glial fibrillary acidic protein (GFAP), the major protein of astrocyte intermediate filaments, was localized with a post-embedding immunogold method, using both unosmicated and osmicated material embedded in epoxy resin. The tissue studied was from a diagnostic brain biopsy on a child with Alexander's disease. This disorder is characterized by proliferation of astrocyte intermediate filaments and formation of Rosenthal fibers. With unosmicated tissue, as in a previous study, extensive labeling of the glial filaments was achieved only when ultra-thin sections were pre-treated with dilute sodium ethoxide, an agent that dissolves plastic. Fifteen-nm gold could be used. With osmicated tissue, localization to glial filaments required pre-treatment with sodium ethoxide and with the oxidizing agent sodium metaperiodate, followed by the use of small (5 nm) colloidal gold. That 5-nm gold was required for labeling filaments in osmicated material suggested that osmication increases problems of penetrability and antigen accessibility within ultra-thin sections. The large Rosenthal fibers were labeled by 15-nm gold in both unosmicated and osmicated material. The methods employed may be useful for electron immunolocalizations to other thin structures in material embedded in epoxy resin.

Effect of raising injection-site skin temperature on isophane (NPH) insulin crystal dissociation

In eight healthy subjects, skin temperature at the injection site was raised from mean +/- SD 31.7 +/- 0.5 to 40.8 +/- 0.9 degrees C 180 min after injection of 0.25 U/kg isophane (NPH; Human Insulatard) insulin and maintained for 180 min. On the control day, skin temperature was kept constant. On warming of the injection site, serum insulin concentration rose from mean +/- SE 14.4 +/- 2.5 to 17.7 +/- 3.1 mU/L after 40 min (P less than .01) but did not change on the control day over the same period. The change in insulin concentration from the prewarming hour was higher on the warming day than control day in the 1st h (123 +/- 8 vs. 93 +/- 7%, P less than .01), 2nd h (115 +/- 14 vs. 83 +/- 9%, P less than .05), and 3rd h (113 +/- 17 vs. 80 +/- 10%, P less than .05) of warming, providing evidence for both early increased absorption of the free-insulin pool surrounding the protamine-insulin complexes and continuing increased dissociation of the complexes.

On-grid immunogold labeling of glial intermediate filaments in epoxy-embedded tissue

On-grid immunogold labeling of structures like intermediate filaments has been difficult to achieve. Presumably this is because such structures are thinner than the thin sections themselves and because gold-labeled reagents remain on the surface and do not penetrate epoxy resins. Many pathologic and other tissues, however, are primarily available as epoxy-embedded blocks, and a postembedding gold procedure capable of detecting such thin structures would be useful. This study aimed to investigate the astrocytic intermediate filament antigen glial fibrillary acidic protein (GFAP) in glutaraldehyde-fixed, epoxy-embedded brain biopsy tissue from a child with Alexander's disease. A protocol was developed for performing on-grid immunogold labeling which minimized nonspecific deposition of gold reagent. The method utilized ovalbumin and skim milk in the washes and diluent for the gold reagent and the same solution with added Tween-20 and high sodium chloride in the diluent for antibodies and normal serum. In grids etched with metaperiodate and hydrogen peroxide, the astrocytic intermediate filaments were only occasionally and sparsely labeled. When an etching procedure with sodium ethoxide was employed, however, extensive labeling was obtained on the astrocytic intermediate filaments. In contrast, the larger, pathological Rosenthal fibers characteristic of Alexander's disease were labeled after both etching procedures, but labeling was enhanced after ethoxide etching. Postosmicated material showed much less labeling. The findings demonstrate that postembedding procedures can be used with epoxy-embedded material to immunolabel thin structures like intermediate filaments.

Exercise augments the absorption of isophane (NPH) insulin

In order to determine the effect of exercise on the rate of absorption of an isophane (NPH) insulin, 7 normal men were studied on two separate occasions using the euglycaemic clamp technique. On one day subjects undertook 60 min of exercise on a treadmill (5 km h-1, 5 degrees slope) 180 min after injection of human isophane (NPH) insulin (0.25 U kg-1), while on the control day they remained at rest throughout the 420 min study. Serum insulin concentrations rose in parallel after injection achieving similar values at 180 min on exercise and control days (13.7 +/- 1.2 (+/- SE) vs 12.0 +/- 1.5 mU l-1; NS), respectively. After the onset of exercise, insulin concentrations rose markedly to a peak of 29.8 +/- 2.2 mU l-1 after 50 min of exercise (p less than 0.001), compared with a slight fall on the control day to 10.4 +/- 1.7 mU l-1 (NS). At the end of the exercise period, serum insulin concentrations returned rapidly to control day values. Glucose infusion requirements rose significantly during the exercise period from 2.8 +/- 0.5 mg kg-1 min-1 to a peak at 235 min of 11.1 +/- 1.2 mg kg-1 min-1 (p less than 0.001), compared with an increase on the control day from 2.0 +/- 0.6 to 2.5 +/- 0.6 mg kg-1 min-1 (NS) over the same period. These results demonstrate an enhanced rate of absorption of an isophane (NPH) insulin during exercise in normal subjects.