The ultrastructure of blebs induced in the hamster jejunum by ethanol.

Previous light microscopic studies showed that perfusion of the hamster jejunum with 4.8% ethanol (ethanol period) in vivo produced fluid-filled subepithelial blisters (blebs) on the villi. These blebs had virtually disappeared within 45 min after the discontinuation of the ethanol perfusion (recovery period). The present study examined these ethanol-induced changes in the jejunum by scanning (SEM) and transmission (TEM) electron microscopy. TEM revealed that ethanol did not damage epithelial cells in areas where blebs were not present. In these areas the basal surfaces of the epithelial cells were attached to the basal lamina, and the lateral intercellular spaces (LIS) were open. In the areas where blebs formed, the stretched epithelial cells which covered the blebs lost their basal anchoring and so could not maintain their LIS. Both SEM and TEM indicate that there was a decrease in the quantity of glycocalyx at the surfaces of cells which covered blebs. Our findings indicate that ethanol does not directly damage epithelial cells but that the cellular damage is due to detachment over the blebs. It is likely that ethanol at first traverses the epithelial layer and then produces stasis in the villus core. Continued fluid transport by the epithelial layer in the presence of statis results in accumulation of the fluid and widely dilated LIS. With subsequent enlargement of the LIS the bases of the cells detach from the basal lamina and blebs are formed.     

Destruction of highly purified cytochromes P-450 associated with metabolism of fluorinated ether anesthetics

The effects of ethanol and acetaldehyde on rat intestinal microvillus membrane integrity and glucose transport function were examined in vitro with purified membrane vesicles. Ethanol could influence glucose transport function by alterations in the conformation of the carrier, the lipid environment surrounding the carrier, or in the transport driving force (Na⁺ electrochemical gradient). Due to the rapid nature of glucose uptake, transport was assayed with the use of an apparatus that permitted uptake measurements as early as 1 s. Ethanol (340 mm) partially and acetaldehyde (44 mm) completely inhibited concentrative glucose uptake throughout the 1-min time course. Their inhibitory effects were reversible and irreversible, respectively. Kinetic measurements made during the initial rate of uptake (at 2 s) with various concentrations of glucose (0.05–8 mm) showed that ethanol and acetaldehyde both caused a decrease in V. Although ethanol did not substantially alter the transport K_m, acetaldehyde increased the K_m almost 50%. To determine whether ethanol or acetaldehyde directly interfered with glucose carrier function, uptake was measured in the presence of equilibrated Na⁺. Only acetaldehyde had a significant inhibitory effect under these conditions. Membrane permeability, as determined by efflux of preloaded 6-carboxyfluorescein dye, increased upon exposure of the vesicles to ethanol or acetaldehyde. Membrane fluidity measurements by fluorescence polarization showed that only acetaldehyde had a significant fluidizing effect. These results indicate that ethanol and acetaldehyde acted to perturb membrane integrity and inhibited glucose uptake indirectly by allowing the Na⁺ gradient to dissipate. Acetaldehyde, which had a stronger inhibitory effect than ethanol, appeared also to directly inhibit carrier function.     

Monosaccharide transport in the mammary gland of the intact lactating rat.

The Michaelis-Menten equation for the utilization of competing substrates was applied to the uptake of 2-deoxy[3H]glucose into the mammary gland of anaesthetized lactating rats. Intracellular water was calculated from total tissue water and sucrose space. Fed rats had a mean transport capacity of 2.2 mumol/min per g of tissue, giving an actual glucose transport in vivo of 1.1 mumol/min per g. Transport decreased by 90% on overnight starvation and returned to normal by 2 h of re-feeding. Similar changes were observed in the 1 min or 5 min transport of circulating 3-O-methylglucose. Transport of 3-O-methylglucose in starved rats was restored towards normal by insulin. In fed rats it increased between parturition and day 12 of lactation. The findings support the proposal that transport is a rate-limiting factor in the mammary utilization of carbohydrate.     

Cholinesterase activity in Japanese quail dusted with carbaryl.

Japanese quail (Coturnix coturnix japonica) were dusted with 5% carbaryl to determine if this topical treatment would alter plasma and brain cholinesterase activities. Within 6 hours after dusting, plasma cholinesterase activity was depressed compared with controls, the depression averaging 20% for females and 27% for males. By 24 hours the cholinesterase activity of females had returned to normal, but the cholinesterase activity of males remained depressed. Brain cholinesterase activity was not affected by the treatment, and there were no overt toxic signs.     

Glucose Deprivation Results in a Lactate Preventable Increase in Adenosine and Depression of Synaptic Transmission in Rat Hippocampal Slices

Abstract: The effect of glucose deprivation on adenosine levels and on synaptic transmission was investigated in rat hippocampal slices. Incubation of hippocampal slices either in glucose-free medium or in the presence of the glucose transport inhibitor cytochalasin B (50 μ M ) increased bath adenosine levels and depressed the extracellularly recorded synaptic potential or population spike. The addition of lactate (10 m M ), a precursor for mitochondrial ATP generation, prevented the elevation in adenosine and the depression of the population spike. These results indicate that the neuroinhibitory modulator adenosine is elevated during glucose deprivation and contributes to the hypoglycemic depression of synaptic transmission. The increase in adenosine during glucose deprivation can be prevented by providing substrate for mitochondrial ATP generation. The present results indicate an interaction between lactate and adenosine such that an increase in lactate may contribute to a decline in adenosine production.     

The Coupling of the Short-Circuit Current to Metabolism in the Urinary Bladder of the Toad

The relationship of the short-circuit current to metabolism was studied in the toad bladder in vitro. Substrates and inhibitors were added to the bathing medium and the effect on the short-circuit current was determined. The spontaneous decline in the short-circuit current that occurred in substrate-free media was prevented or reversed by the addition of glucose, pyruvate, lactate, or β-hydroxybutyrate, whereas acetate and tricarboxylic acid cycle intermediates had no effect. A variety of metabolic inhibitors depressed the short-circuit current; depression by iodoacetate and by malonate was delayed by prior addition of pyruvate or lactate but not by glucose. The ability of a substrate to stimulate the current did not correlate with its rate of oxidation to CO₂. On the basis of earlier studies, the metabolic effects on the short-circuit current were assumed to reflect equivalent effects on the rate of active Na transport. It is suggested that the energy for Na transport is provided not by a general cellular metabolic pool but by a specific metabolic pathway or pathways spatially linked to the transport mechanism.     

Hypoglycemic effects of Coccinia indica: inhibition of key gluconeogenic enzyme, glucose-6-phosphatase.

Coccinia indica (Family: Cucurbitaceae, locally known as telakucha) leaves were extracted with 95% ethanol. Following evaporation of the solvents, the residue was suspended in distilled water. When this suspension was fed orally to male normal-fed and 48-hr starved rats, the blood glucose was lowered 21% (P less than 0.01) in normal-fed and 24% (P less than 0.001) in 48-hr starved animals respectively. Starvation had induced a 3-fold increase in the activity of glucose-6-phosphatase and this activity was depressed 19% (P less than 0.05) by extract feeding while basal activity of the enzyme in normal-fed rats remained unaffected. Consistent with the depression of glucose-6-phosphatase, urea cycle enzyme arginase was also depressed 21% (P less than 0.001) and 12% (P less than 0.01) in the liver of 48 hr-starved and normal-fed animals respectively. Unlike glucose-6-phosphatase, starvation induced levels of gluconeogenic enzymes alanine aminotransferase and aspartate aminotransferase were not affected by Coccinia extract. These results suggest that the hypoglycemic effect of C. indica is partly due to the repression of the key gluconeogenic enzyme glucose-6-phosphatase.     

Comparison of anti-diabetic effects of polysaccharides from corn silk on normal and hyperglycemia rats

Corn silk is well known and frequently used in traditional Chinese herbal medicines. Polysaccharides of corn silk (POCS), which were extracted by distilled water and precipitated by 80% ethanol solution, were evaluated for its anti-diabetic effect on streptozotocin (STZ)-induced diabetic rats. The results demonstrated that daily treatment with 100-500 mg/kg body weight of POCS on the diabetic rats could not only lead a significant decrease on the animal's blood glucose (BG) level, but also reduce the serum lipid level including total cholesterol (TC) and total triglyceride (TG) after determination. The oral glucose tolerance test (OGTT) was also performed to evaluate hypoglycemic effects. Through the measurements of measuring autonomic activity times and rolling stick times, the results also exhibited that the animals had been depressed by dimethyl-biguanide, but protected by the POCS. The POCS showed good antidepressant activity and lengthened remarkably the activity time during the autonomic activities test and exhibited a dose dependent activity.     

Electron microscopic investigations of zymomonas mobilis cells grown in low and high glucose concentrations

Summary Zymomonas mobilis cells grown in the presence of low and high glucose concentrations were examined by electron microscopy. Using ultrathin sectioning and agar diffusion method, significant changes in morphology were observed. Although the fine structure resembles that of a typical gram-negative bacterium, changes in glucose concentration and phases of growth lead to large cell wall vesicle or blebs formation. The possible implications of this morphological change to glucose uptake and ethanol formation are discussed.     

Expression of a heterologous xylose transporter in a <Emphasis Type="Italic">Saccharomyces cerevisiae</Emphasis> strain engineered to utilize xylose improves aerobic xylose consumption

The goal of this investigation was to determine the effect of a xylose transport system on glucose and xylose co-consumption as well as total xylose consumption in Saccharomyces cerevisiae. We expressed two heterologous transporters from Arabidopsis thaliana in recombinant xylose-utilizing S. cerevisiae cells. Strains expressing the heterologous transporters were grown on glucose and xylose mixtures. Sugar consumption rates and ethanol concentrations were determined and compared to an isogenic control strain lacking the A. thaliana transporters. Expression of the transporters increased xylose uptake and xylose consumption up to 46% and 40%, respectively. Xylose co-consumption rates (prior to glucose depletion) were also increased by up to 2.5-fold compared to the control strain. Increased xylose consumption correlated with increased ethanol concentration and productivity. During the xylose/glucose co-consumption phase, strains expressing the transporters had up to a 70% increase in ethanol production rate. It was concluded that in these strains, xylose transport was a limiting factor for xylose utilization and that increasing xylose/glucose co-consumption is a viable strategy for improving xylose fermentation.     

Photosynthetic Depression at High Thallus Water Contents in Lichens: Concurrent Use of Gas Exchange and Fluorescence Techniques with a Cyanobacterial and a Green Algal Peltigera Species

Abstract: Lichens, being poikilohydric, have varying thallus water contents (WC) and show a complex interaction between net photosynthesis (NP) and WC. NP can be depressed at low WC (desiccation effects) and, in some species, also at high WC. In the latter case the depression is normally ascribed to increased CO₂ diffusion resistances through water blockage. Recently, an earlier explanation, that the depression at high WC is due to recycling of CO₂ from increased dark respiration processes (DR), has been given renewed prominence. The two explanations were distinguished by the concurrent use of gas exchange and chlorophyll fluorescence techniques to investigate NP: WC relationships in the lichens Peltigera leucophlebia (green algal) and P. neckeri (cyanobacterial). Both species had a distinct optimal WC for NP with depressed values at low and high WC. The maximal quantum yield for both CO₂ fixation (initial slope of light response curves of NP) and photosystem II (fluorescence signals of dark-adapted thalli) was depressed only at low WC and remained high at optimal and greater WC. In contrast, the relative electron transport rate (ETR, derived from fluorescence signals of thalli in the light) tracked NP and was depressed at low and high WC. The depression of both NP and ETR at high WC (not that at low WC) could be prevented by using elevated external CO₂ concentrations. A single, linear relationship was found between all values of gross photosynthesis (NP + DR) and ETR regardless of external CO₂ concentration or WC. Our results show that, for these lichens, the depression in NP at high WC is a real fall in photosynthetic rate of the photobionts and is not due to recycling of CO₂. The removal of the depression in NP and ETR at high WC by using elevated external CO₂ levels allows us to conclude that an additional CO₂ diffusion resistance is present.     

Irreversible inhibition of the labellar sugar receptor of the blowfly, Phormia regina, by periodate-activated starch

Activated starch bearing aldehyde groups, which is prepared by oxidation of soluble starch with sodium periodate (NaIO₄) and binds amino groups strongly, irreversibly inhibited the responses of taste receptors in the blowfly, Phormia regina. After highly activated starch (oxidized with 0.2 M NaIO₄) was applied through the tip opening of the chemosensillum, the responses of the sugar, salt and water receptors were nonspecifically depressed. The chemoreceptor membranes were nonspecifically protected by all the sugars tested against the treatment with highly activated starch, but in the case of the response to fructose, the membrane was specifically protected by fructose. Mildly activated starch (oxidized with 0.04 M NaIO₄), however, selectively depressed the sugar response. The depression depended on the pH of the solution containing the mildly activated starch. After treatment at pH 8.6, the response to sucrose, maltose or glucose was not depressed at all, but that to fructose or galactose was depressed. After treatment at pH 9.0, however, the responses to all sugars were depressed. Such depression of the sugar response lasted for 20 h or more after treatment.     

The effects of abdominal irradiation on intestinal transport in the rat as assessed with isolated epithelial cells

The time course of the effect of exposure to sublethal irradiation on transport of several substrates by the intestine has been studied using isolated enterocytes. Rats received a single dose of 6 Gy to the abdomen, and isolated intestinal epithelial cells were prepared 3, 7, and 14 days later. The ability of the cells to take up D-glucose, L-leucine, and glycyl-L-leucine was assessed using 2.5-min incubation periods and was compared with the uptake in control cells. It was found that the protein content of the cells increased after irradiation, and although some of this was the result of increased binding of albumin to the cells there was also a nonspecific increase in most cell proteins. Consequently uptake data were expressed per unit number of cells and not per milligram of cell protein. Comparison of uptake expressed in this way showed that D-glucose and glycyl-L-leucine uptake was elevated 3 days after irradiation while that of L-leucine was unaffected. By 14 days after irradiation the glucose and glycyl-L-leucine uptake had returned to normal but the L-leucine transport was depressed. These data indicate that the effects of irradiation upon substrate transport in the intestines are not uniform and that although the cell population is initially reduced the remaining cells can compensate by increasing their transport capacity.     

Electron Microscope Studies of Nuclear Extrusions in Pancreatic Acinar Cells of the Rat

This paper describes "blebs" protruding from the surface of the nucleus into the cytoplasm. The "blebs" are separated from the cytoplasm by 2 membranes which are continuous with the outer and inner nuclear membranes. The "blebs" contain 3 structurally distinct substances. Two of these substances (β and γ substances) are similar to extranucleolar karyoplasm and nucleolar material. The other substance (α substance) is present in every "bleb," but it cannot be readily compared to a recognizable nuclear structure. Cytoplasmic vesicles are described that are apparently different from the Golgi vesicles or the vesicular component of the ergastoplasm. It is suggested that these vesicles may be of nuclear "bleb" origin. A dark karyoplasmic zone extending from the region of the nucleolus into the nuclear "bleb" is shown. This zone may be similar in some respects to the preformed pathway ("Leitbahn") described by Altmann (3) and Hertl (28) and could reflect movement of nuclear material from the nucleolar region into the cytoplasm. The "blebs" are thought to be homologous to structures described by many light microscopists, but they are considerably larger than the nuclear "blebs" described previously by electron microscopists.     

Halothane-Induced Alterations of Glucose and Pyruvate Metabolism in Rat Cerebra Synaptosomes

Synaptosomes isolated from rat cerebra were used to study the effects of the inhalational anesthetic, halothane, on cholinergic processes. To identify possible mechanisms responsible for the depression of acetylcholine synthesis, we examined the effects of halothane on precursor metabolite metabolism involved with supplying the cytosol with acetyl-CoA for acetylcholine synthesis. Three percent halothane/air (vol/vol) depressed 14CO2 evolution from labeled pyruvate and glucose. Steady-state 14CO2 evolution from [1-14C]glucose was depressed 84% by halothane, while 14CO2 evolution from [6-14C]glucose and [3,4-14C]glucose was decreased 67 and 52%, respectively, when compared with control conditions. Halothane inhibited the activities of both pyruvate dehydrogenase (14% depression) and ATP-citrate lyase (32% depression). Total synaptosomal acetyl-CoA concentrations were unaffected by halothane. Three percent halothane/air (vol/vol) caused a 77% increase in medium glucose depletion rate from 1.38 nmol (mg protein)-1 min-1 to 2.44 nmol (mg protein)-1 min-1. Production of lactate by the synaptosomes in the presence of halothane increased by 231% from a control rate of 1.44 nmol (mg protein)-1 min-1 to 4.77 nmol (mg protein)-1 min-1. Lactate production rate from pyruvate was also enhanced by 56% in the presence of halothane. These data lend support to the concept that the NAD+/NADH potential may be involved in the halothane-induced depression of acetylcholine synthesis.     

Tissue-specific changes in protein synthesis associated with seasonal metabolic depression and recovery in the north temperate labrid, Tautogolabrus adspersus

The tissue-specific changes in protein synthesis were tracked in relation to the seasonal metabolic depression in cunner (Tautogolabrus adsperus). In vivo protein synthesis rate and total RNA content were determined in liver, white muscle, brain, heart, and gill during periods of normal activity before metabolic depression, entrance into and during winter dormancy, and during the recovery period. The decrease in water temperature from 8 degrees C to 4 degrees C was accompanied by a 55% depression of protein synthesis in liver, brain, and heart and a 66% depression in gill. Protein synthesis in white muscle fell below detectable levels at this temperature. The depression of protein synthesis is an active process (Q(10) = 6-21 between 8 degrees C and 4 degrees C) that occurs in advance of the behavioral and physiological depression at the whole animal level. Protein synthesis was maintained at these depressed levels in white muscle, brain, heart, and gill until water temperature returned to 4 degrees C in the spring. Liver underwent a hyperactivation in the synthesis of proteins at 0 degrees C, which may be linked to antifreeze production. During the recovery period, a hyperactivation of protein synthesis occurred in white muscle, which is suggestive of compensatory growth, as well as in heart and liver, which is considered to be linked to increased activity and feeding. Seasonal changes in total RNA content demonstrate the depression of protein synthesis with decreasing temperature to be closely associated with translational capacity, but the stimulation of protein synthesis during recovery appears to be associated with increased translational efficiency.     

Castelli risk indexes 1 and 2 are higher in major depression but other characteristics of the metabolic syndrome are not specific to mood disorders

Aims

This study examined whether Castelli risk indexes 1 (total/high-density lipoprotein (HDL) cholesterol) and 2 (low density lipoprotein (LDL)/HDL cholesterol) and other shared metabolic disorders might underpin the pathophysiology of the metabolic syndrome, major depression or bipolar disorder.

Main methods

This cross-sectional study examined 92 major depressed, 49 bipolar depressed and 201 normal controls in whom the Castelli risk indexes 1 and 2 and key characteristics of the metabolic syndrome, i.e. waist/hip circumference, body mass index (BMI), systolic/diastolic blood pressure, total cholesterol, low-density lipoprotein (LDL) and HDL cholesterol, triglycerides, insulin, glucose, hemoglobin A1c (HbA1c) and homocysteine were assessed.

Key findings

Castelli risk indexes 1 and 2 were significantly higher in major depressed patients than in bipolar disorder patients and controls. There were no significant differences in waist or hip circumference, total and LDL cholesterol, triglycerides, plasma glucose, insulin, homocysteine and HbA1c between depression and bipolar patients and controls. Bipolar patients had a significantly higher BMI than major depressed patients and normal controls.

Significance

Major depression is accompanied by increased Castelli risk indexes 1 and 2, which may be risk factors for cardiovascular disease. Other key characteristics of the metabolic syndrome, either metabolic biomarkers or central obesity, are not necessarily specific to major depression or bipolar disorder.