Associative growth behavior of dahi and yoghurt starter cultures with Bifidobacterium bifidum and Lactobacillus acidophilus in buffalo skim milk

We report here for the first time variations in the viability and biochemical activity of dahi and yoghurt cultures, when grown together with therapeutic cultures, such as Lactobacillus acidophilus I and Bifidobacterium bifidum R, in buffalo skim milk. Nearly one log reduction in mesophilic lactic count was observed in dahi supplemented with probiotic cultures after 18 h of incubation at 30 °C. Associative growth increased the titratable acidity (TA) of dahi marginally (from 0.93 to 1.18 % lactic acid) but reduced the TA in yoghurt (from 1.68 to 1.44 % lactic acid). Probiotic culture supplementation reduced volatile acidity (VA) (from 36.0 to 15.8 ml) and diacetyl (from 4.05 to 2.80 ppm) and tyrosine (from 0.46 to 0.36 μg tyrosine/g curd ) content in dahi, whereas it increased VA (from 8.2 to 8.6 ml of 0.01 % NaoH/50 g) and acetaldehyde (from 28.4 to 34.6 ppm) production in yoghurt. Based on these results, the associative growth had no effect on proteolytic activity of probiotic yoghurt.     

Cytotoxic activity of lactobacilli isolated from plant and dairy sources

Forty four cultures of Lactobacilli isolated from their natural sources such as dahi, raw milk and fermenting rice-pulse doughs etc. along with four standard strains of Lactobacilli were assayed for their cytotoxic activity against three secondary tumour cell lines. Three cultures isolated from dahi samples and identified as Lactobacillus casei D-34, L. casei D-48a, L. plantarum D-70a along with one standard strain L. casei B 1922 exhibited significant cytotoxic activity in the range of 30 to 36%.     

Draft genome sequence of Lactobacillus plantarum strain DMR17 isolated from homemade cow dahi of Sikkim Himalayan region: an evaluation of lactate fermentation and secondary metabolism

Archives of Microbiology - Lactobacillus plantarum DMR17 was isolated from homemade cow dahi of Sikkim Himalayan region of India. Here, we report the draft genome sequence of this strain. A total...     

Utilization of glucose during exercise in relation of meal-timing

The effect of glucose administration was studied on its utilization during exercise carried out in the hours 500-700, 1100-1300, 1700-1900, 2300-100. The control group comprised animals at rest which had one or two glucose loads. Circadian variability of blood glucose level was observed in response to glycaemic stimulation in control animals. In the animals during exercise the circadian changes of glucose level depended on the time after glucose administration and the duration of exercise. Glucose utilization during exercise was not identical at various times of the 24-hour period. The greatest fall of blood glucose was observed at 1800 after one as well as after two glucose loads. Glucose administration after one hour of exercise prevented hypoglycaemia development.     

Dietary fat type alters glucose metabolism in isolated rat hepatocytes

Dietary fat type can influence the regulation of carbohydrate metabolism in multiple tissue types. The influence of feeding high-fat (40% of kilocalories) diets containing either menhaden oil (MO) or coconut oil (CO) on hepatic glycogenolytic and gluconeogenic capacities was studied in isolated rat hepatocytes. Estimates of both glycogenolytic and gluconeogenic capacities were performed on hepatocytes isolated from fed and fasted animals, respectively. In MO-fed animals, both basal and hormone-stimulated rates of glucose production were significantly greater than those in CO-fed animals. However, both groups displayed a similar maximal increase in glucose production above basal for glucagon and epinephrine (2.3- and 1.9-fold, respectively). Basal rates of adenosine 3′,5′-cyclic phosphate (cAMP) production were not different between groups whereas glucagon-stimulated cAMP production was increased twofold in the MO-fed group. In both MO and CO groups, the addition of 10 nM insulin reduced glucose production in fed animals to similar absolute rates. In animals fasted for 24 hours, gluconeogenic capacity was estimated using 10 mM pyruvate, lactate, or glycerol. Glucose production from all substrates was significantly greater in CO-fed animals. In addition to increased gluconeogenic rates, maximal phosphoenolpyruvate carboxykinase (PEPCK) activity was increased in the CO-fed group. Insulin reduced glucose production in both dietary groups, but the absolute rate of glucose production was 28% greater in the CO-fed group relative to the MO-fed group. In summary, dietary fat type can markedly influence the regulation of hepatic glucose metabolism in multiple metabolic pathways. MO feeding promoted glycogenolysis and sensitivity to insulin whereas CO feeding favored gluconeogenesis and reduced insulin sensitivity.     

Effect of chronic psychological stress on insulin release from rat isolated pancreatic islets

Despite documented studies, the exact role of stress on diabetes is still unclear. The present study investigates the effect of chronic psychological stress on insulin release from isolated rat pancreatic islets. Male Wistar rats were divided into two groups of control and stressed (n=8/group). The animals of the stressed group were exposed to restraint stressors (1 h twice daily) for 15 or 30 consecutive days. At the beginning and end of the experimental periods, the animals were weighed and blood samples taken to determine the fasting plasma levels of glucose, insulin and corticosterone. On the following day the pancreatic islets of 5/group of the above animals were isolated and the static release of insulin in the presence of different glucose concentrations (2.8, 5.6, 8.3, 16.7 mM) was assessed. The results showed that in the stressed group, fasting plasma glucose levels were increased significantly on the 15th day as compared to the control group. However there was no significant increase on the 30th day. Fasting plasma insulin was significantly decreased on the 15th and 30th days of the experiment in the stressed group. Stressed rats showed significantly higher fasting plasma corticosterone levels, only on the 15th day, as compared to the control rats. In response to increasing concentrations of glucose, insulin release from islets of the stressed group was increased significantly on the 30th day of the experiment as compared to the control group. We conclude that chronic psychological stress could increase responsiveness of pancreatic beta cells to glucose, in vitro, and thus, low insulin levels of the stressed animals, in vivo, may be due to reason(s) other than the reduction of insulin releasing capacity of pancreatic beta cells.     

Glucagon auto-immunization fails to stimulate food intake or growth in young rabbits

1. To further investigate the possible role of glucagon in appetite control, weaned rabbits were auto-immunized using a glucagon-bovine serum albumin conjugate (G-BSA). 2. At weekly intervals, the animals were weighed and blood samples collected and subsequently analysed for insulin, glucose and glucagon concentrations. Weekly food consumption was also recorded. 3. At the termination of the experimental period, each animal was subjected to a glucose tolerance test. Following this procedure, the animals were killed and the livers excised and frozen for subsequent glycogen determination. 4. No differences between the controls and auto-immunized group were found at any time for weekly weight gain, food intake, blood glucose or insulin concentrations. 5. Glucagon concentrations in the control group remain stable over the 7 week period; however, after the third week of the experiment, no glucagon could be detected in the blood of any of the auto-immunized animals. 6. The auto-immunized animals had significantly different glucose tolerance profiles and also had significantly more liver glycogen than the control group.     

Altered glucose tolerance in rats exposed to maternal low protein diets in utero

The response to an intravenous glucose load was evaluated in four groups of rats following fetal exposure to maternal diets containing 18, 12, 9 or 6% protein. The animals differed nutritionally only in terms of this prenatal experience. Animals in the 6% protein exposed group exhibited lower body weights at all ages, whilst the body weights of 9 and 12% protein exposed rats did not differ from the control group. At 9 weeks of age, a 2 g/kg body weight intravenous glucose load was cleared in 60 min by 18% protein exposed, control rats and 12% protein exposed rats. Peak blood glucose concentrations in these animals were 27.2 and 27.1 mM, respectively. Rats exposed to 9% protein in utero also cleared the glucose load in 60 min, but peak blood glucose concentrations were lower (24.4 mM), and the area under the glucose tolerance curve was 28% lower than in controls. Rats in the 6% protein exposed group cleared the glucose load in 40 min and peak blood glucose levels were only 22.1 mM. The area under the glucose tolerance curve was reduced by 40% relative to controls. When the glucose tolerance test was repeated in animals aged 44 weeks, no differences in peak glucose concentrations, area under the curve or rates of glucose clearance were observed. In utero exposure of rats to maternal low protein diets has been shown, therefore, to alter glucose tolerance in young adulthood through an, as yet, undefined mechanism.     

Effects of Estrogen on Glucose Uptake by Rat Muscle

The isolated rat diaphragm was used to study the effects of 17β-estradiol on basal and insulin-mediated glucose uptake. Rats were injected with estradiol for 2 wk in daily doses of 10 μg/100 g of body weight and were compared to untreated control animals. Estrogen treatment resulted in a 16% decrease in basal glucose uptake by diaphragm muscle as compared to controls. In contrast, in the presence of insulin, glucose uptake by muscle increased 103% above basal in estradiol-treated animals as compared to a 38% rise in the control group. The absolute rate of glucose uptake induced by insulin in the estradiol treated animals (5.8 mg/g/hr) was 22% higher than in controls. These findings were not accompanied by changes in weight gain, plasma glucose and plasma immunoreactive insulin concentrations in the treated animals. In vitro incubation of diaphragm muscle with estradiol did not have an effect on basal or insulin-mediated glucose uptake.     

Glucagon secretion by dispersed alpha cell enriched islets from streptozotocin treated hamsters in perifusion

Streptozotocin (70 mg/kg) was administered intravenously to female Syrian hamsters. The hamsters received insulin (5U/animal/day). Insulin treatment was withdrawn 3 days before sacrifice in one group, while another group was maintained on insulin until sacrifice. Ten to 14 days following streptozotocin administration the animals were killed, and the pancreatic islets isolated and subsequently dispersed. Islet DNA content was decreased while the glucagon content was elevated by streptozotocin treatment. The glucagon secretory responsiveness of the dispersed alpha cells of control animals was stimulated by glucopenia and decreased by glucose. Alpha cells of streptozotocin hamsters were not only suppressed but were actually stimulated by high glucose concentrations. Treatment with insulin in vivo but not in vitro, resulted in a restoration of the alpha cells responsiveness to glucose suppression. Dispersed alpha cells from control and streptozotocin treated animals were stimulated by arginine. Basal and total glucagon secretion was greatest in dispersed alpha cells from streptozotocin treated animals. We concluded: that the paradoxical response of alpha cells to glucose noted in diabetes is not due to short term insulin deprivation or the lack of morphologic contact with beta cells; that the alpha cells require and insulin stimulated islet metabolite and extra islet materials to respond appropriately to glucose; and that the alpha cells response to arginine is mediated independently of glucose regulation.     

Intervention of Acidophilus-casei dahi and Wheat bran against molecular alteration in colon carcinogenesis

An in vivo trial was conducted on seventy five rats allocated to three groups, first group was DMH control group, second group was Wheat bran-DMH group (WB-DMH) in which wheat bran was given along with DMH (1,2-dimethylhydrazine) injection, third group was Wheat bran-DMH-Ac Dahi group in which both wheat bran and Acidophilus-casei dahi (a probiotic microorganisms fermented dairy product) was given along with DMH injections. Animals received subcutaneous injections of DMH at a dose rate of 20 mg/kg body weight, once weekly for 15 weeks. The rats were dissected at 40th week of experiment and comet assay was done in colonic cells to assess the DNA damage. The c-myc and cox-2 expression was studied in rat tumour. A significant reduction in DNA damage (48.2%) was observed in WB-DMH-Ac Dahi group as compared to DMH control group (87.8%). The c-myc and cox-2 mRNA level was found highest in DMH control group as compared to WB-DMH and WB-DMH-Ac Dahi group. The results of present study show the enhanced protective potential of Acidophilus-casei and wheat bran against DMH induced molecular alteration in colonic cells during carcinogenesis.     

Studies on the (pro) insulin biosynthesis of islets of Langerhans of sand rats (Psammomys obesus).

By feeding a regular laboratory chow, sand rats (Psammomys obesus) from our breeding colony gained different body weights, though they received approximately the same quantity of calories. Sand rats, reaching a body weight above 160 g (group B) showed significantly increased blood glucose values in contrast to the animals with a body weight under 160 g (group A). Isolated pancreatic islets of these two groups of sand rats were incubated with [3H]-leucine to study the incorporation of this amino acid into proinsulin and insulin. The incorporation into proteins of pancreatic islets of sand rats of group B was stimulated by 0.45 mg and 3.0 mg/ml glucose. In group A there was no further stimulation from 0.45 mg to 3.0 mg/ml glucose. Insulin secretion could be stimulated by glucose in both groups, but the stimulation was stronger in group B than in group A.     

Metabolic effects of dietary lactose in adult female rats

As an outgrowth of our interest in the potential toxicity of dietary galactose, we investigated the metabolic effects of high lactose diets in Long-Evans female rats. Seventy-five Long-Evans female rats (25-day-old) were randomized to receive one of 3 diets for 7 months: glucose diet (CON); low lactose diet (10.5%, LLD); or a high lactose diet (41.9%, HLD). Necropsy was performed seven months after randomization. HLD animals had significantly lower body weights than controls (P < 0.01). These animals continued to grow, however at a retarded rate compared to the CON group. The HLD group also had significantly lower triglyceride and non-esterified fatty acid levels than the CON group (P < 0.01 and P < 0.05). Serum glucose concentrations were lower in the HLD group compared to CON animals (P < 0.05), while serum insulin levels were lower than both the LLD and CON animals (P < 0.01 and P < 0.05). Leptin exhibited a similar trend. Thyroid studies revealed no difference in TSH between groups. Free T4 was significantly higher in HLD rats compared to LLD and CON rats while free T3 was lower in the HLD group (P < 0.05). This indicates a possible impairment in T4 to T3 conversion. Our data suggests that a long-term high lactose diet is associated with a decrease in insulin and leptin levels, and an increase in the insulin to glucose ratio. However, these changes are seen in the presence of a decreased body mass. A significant effect on thyroid hormone metabolism is also seen, and may be an adaptive mechanism in lactose-fed rats.     

Glucose metabolism in vivo in crossbred Holstein cattle feeding on different types of roughage during late pregnancy and early lactation

An experiment was carried out to study the glucose kinetics of crossbred Holstein cattle feeding on either hay or 5% urea treated rice straw during late pregnancy (21 days prepartum) and early lactation (30 days postpartum). In all 16 pregnant heifers (23–25 months of age) were selected for the experiments, including eight animals of two breed types, Holstein Friesian×Red Sindhi (50:50=50% HF) and Holstein Friesian×Red Sindhi (87.5:12.5=87.5% HF). They were divided into four groups of four animals each. Animals from the same breed type in each group were fed with either rice straw treated with 5% urea or pangola hay (Digitaria decumbens) as the source of roughage throughout the experiments. The glucose turnover rate in both types of crossbred Holstein cattle was determined using a continuous infusion of [U-¹⁴C] and 3-[³H]glucose during late pregnancy and early lactation. Total glucose entry and utilization rates increased significantly during lactation for all groups. Recycling of [C]glucose was, approximately, 20% in both crossbred cattle fed either hay or urea treated rice straw and was unaffected by the stage of late pregnancy or early lactation. Comparing 50 and 87.5% HF animals, arterial plasma glucose concentrations were slightly higher during pregnant periods but significantly higher in lactating periods in 50% HF animals. The ratio of specific radioactivity of arterial blood bicarbonate relative to that of arterial blood [¹⁴C]glucose in the lactating period, significantly decreased in 50% HF animals fed either urea treated rice straw or hay. An increase in udder blood flow during early lactation was significantly higher in 87.5% HF animals than in 50% HF animals. The uptake, arteriovenous differences and extraction ratio for glucose across the udder, significantly increased in the lactating period for all crossbred animals. Glucose uptake by the udder of 87.5% HF animals accounted for 65% of the total glucose turnover rate compared to a value of 46% in the lactating 50% HF animals. It can be concluded that both crossbred cattle fed either urea treated rice straw or hay exhibit the same body glucose turnover rate. The 87.5% HF animal has the genetic potential for a high milk yield and has high body and udder glucose metabolisms compared with 50% HF animals.     

Hypoglycemic action of Cyclocarya paliurus (Batal.) Iljinskaja in normal and diabetic mice

This study examined the hypoglycaemic activity of Cyclocarya paliurus (Batal.) Iljinskaja (C. paliurus) in ICR mice by oral glucose tolerance testing. The blood glucose level was significantly lower in the C. paliurus extract treatment group than in the control group after animals were given sucrose. This difference was not observed following the administration of glucose. We demonstrated that the chronological change in the level of blood glucose in genetically hyperglycemic obese KK-Ay mice is significantly lower when C. paliurus extract is administered daily for three weeks. An in vitro study showed that C. paliurus inhibits alpha-glucosidase, a disaccharide-degrading enzyme in the small intestinal mucosa, leading to a decrease in the absorption of glucose into the blood and a subsequent lowering of the blood glucose level.     

Dependency of lactose absorption on lactase activity in starved rats

The effects of starvation on intestinal disaccharidase activities and disaccharide absorption were studied in rats. Adult male rats were starved for either 16 or 72 h and the specific activity of lactase and sucrase was determined together with the absorption of lactose, sucrose, and glucose in vitro by the everted sac technique. The specific activity of lactase was significantly higher and the specific activity of sucrase was lower in the 72-h starved animals when compared with the 16-h starved group. The higher specific lactase activity in the 72-h starved animals was reflected in enhanced absorption of lactose as determined by the transfer of the constituent monosaccharides into the serosal fluid. The transfer of glucose into the serosal fluid by the glucose sac was also higher in the 72-h starved rats but not to the same extent as that of lactose. The absorption of sucrose was not significantly different between the two groups of animals. This study shows that the increase of intestinal lactase activity induced by starvation of adult rats correlates with in vitro increased lactose absorption.     

Regulation of hepatic lipogenesis in starved and diabetic animals by thyroid hormone

The effects of intragastric feeding with glucose and of the administration of L-triiodothyronine (T₃) on in vivo rates of hepatic lipogenesis were investigated in control (fed ad libitum on norrnal diet), diabetic (fed ad libitum on normal diet), fat-fed (fed ad libitum on high-fat diet), and starved (food removed for 48 h) rats. Two days of T₃ treatment increased hepatic lipogenesis in control and fat-fed animals but not in the diabetic or starved animals, although increases in lipogenesis in diabetic animals were observed after 4 days of T₃ treatment. Intragastric glucose feeding increased hepatic lipogenesis in the livers of control animals and T₃-treated control animals. Such increases are mediated by an increase in the circulating insulin concentration, as increases are not observed in diabetic rats or T₃-treated diabetic rats. Glucose feeding failed to increase hepatic lipogenesis in fat-fed rats or starved rats. Insulin injection together with glucose feeding increased lipogenesis in the fat-fed group but not the starved group; i.e., impaired insulin secretion following an oral glucose load may in part explain the lack of response in the fat-fed but not the starved animals. Marked increases in hepatic ]ipogenesis after glucose feeding were, however, observed if either the starved or the fat-fed animals were treated with T₃, The physiological implications of these observations are discussed.     

Chronic leptin treatment enhances insulin-stimulated glucose disposal in skeletal muscle of high-fat fed rodents

The aim of this investigation was to evaluate if chronic leptin administration corrects high fat diet-induced skeletal muscle insulin resistance, in part, by enhancing rates of glucose disposal and if the improvements are accounted for by alterations in components of the insulin-signaling cascade. Sprague-Dawley rats consumed normal (CON) or high fat diets for three months. After the dietary lead in, the high fat diet group was further subdivided into high fat (HF) and high fat, leptin treated (HF-LEP) animals. HF-LEP animals were injected twice daily with leptin (5 mg/100 g body weight) for 10 days, while the CON and HF animals were injected with vehicle. Following the treatment periods, all animals were prepared for and subjected to hind limb perfusion. The high fat diet decreased rates of insulin-stimulated skeletal muscle glucose uptake and glycogen synthesis in the red gastrocnemius (RG), but did not affect glycogen synthase activity, rates of glucose oxidation or nonoxidative disposal of glucose. Of interest, IRS-1-associated PI3-K activity and total GLUT4 protein concentration were reduced in the RG of the high fat-fed animals. Leptin treatment increased rates of insulin-stimulated glucose uptake and glucose oxidation, and normalized rates of glycogen synthesis. Leptin appeared to mediate these effects by normalizing insulin-stimulated PI3-K activation and GLUT4 protein concentration in the RG. Collectively, these data suggest that chronic leptin treatment reverses the effects of a high fat diet thereby allowing the insulin signaling cascade and glucose transport effector system to be fully activated which in turn affects the amount of glucose that is transported across the plasma membrane and made available for glycogen synthesis.     

The effects of selected antimicrobials on glucose transport in the rat intestine.

To determine whether oxytetracycline hydrochloride and the sodium salt of ampicillin have any adverse effects on the rat intestine, enteric enzyme levels and glucose transport rates were measured in vitro in rats. The intestinal transport of glucose did not differ significantly between control animals and those pretreated with ampicillin. For animals pretreated with oxytetracycline, the transport rates were significantly lower than those for the control group. The difference between the ampicillin and oxytetracycline groups, however, was not statistically significant. No significant differences in enteric levels of sucrase and maltase activity were found between any of the groups. The possibility that some antimicrobial agents may interfere with the absorption of nutrients suggested the need for caution in using these drugs in experimental animals.     

The influence of mildronate on peripheral neuropathy and some characteristics of glucose and lipid metabolism in rats with the streptozotocin model of diabetes mellitus

Rats with the streptozotocin (STZ) model of diabetes mellitus were treated with mildronate (100 mg/kg daily, per os or intraperitoneally) for 6 weeks. Body weight, blood glucose, triglycerides, ketone body concentrations, percent of glycated hemoglobin (HbA1c%), glucose tolerance, and the development of neuropathic pain were monitored throughout the whole experiment. The mildronate treatment completely prevented the development of the diabetic neuropathy from the first week up to the end of experiment. In the group of diabetic animals treated with mildronate a significant decrease of blood glucose was observed on the fourth week of the treatment, the level of triglycerides decreased from the third to sixth weeks. Mildronate also decreased accumulation of glycated hemoglobin on the sixth week and improved glucose tolerance compared with untreated animals. The data obtained confirm applicability of mildronate for therapy of diabetes mellitus and its complications.