Blood Glucose Assay Using Dextrostix and a Reflectance Meter

The ‘Dextrostix’-reflectance meter system for blood glucose analysis has been evaluated using a blood glucose reference method. A high degree of concordance between the two methods was obtained when analyses were performed by skilled laboratory staff on venous blood samples containing fluoride, with a 75 s contact time.

Skilled laboratory staff performed significantly better than unskilled staff. Capillary blood glucose concentrations correlated poorly with concentrations in venous blood samples taken at the same time as the capillary blood.

Maternal undernutrition during late pregnancy in sheep. Its relationship to maternal condition, gestation length, hepatic physiology and glucose metabolism

There is a paucity of information on the metabolic effects of undernutrition of the ewe carrying multiple fetuses in late pregnancy. In the present study the effects of induction of ketosis from 132 d gestation in ewes carrying twin fetuses were compared with a control group. The ewes were well fed up to 132 d. Ketotic ewes showed a loss of condition score from 3.7 (SE 0.11) at 130 d gestation to 3.0 (SE 0.15) 10 d later after clinical recovery, compared with control twin-pregnant ewes (P < 0.01). The weight loss during the same time period was from 70.6 (SE 2.7) kg at 130 d to 64.2 (SE 2.7) kg at 140.d gestation. As expected, both groups lost weight and condition score in the first 28 d of lactation. Induction of ketosis caused a significant shortening of the gestation period to 142.8 (SE 0.7) d compared with 150 (SE 0.4) d in normal twin-pregnant ewes (P < 0.001). Ewes with induced ketosis recovered clinically and showed a normal feed intake by 3.4 (SE 0.07) d; three required treatment. Induction of ketosis resulted in reduction of hepatic uptake of bromosulphthalein (P < 0.01) and its biliary excretion (P < 0.05), metabolic clearance rate (P < 0.001), fractional clearance (P < 0.001) and 15 and 30 min retention compared with control twin-pregnant ewes. Most values had returned to normal by the first week of lactation. It is thought that in human pregnancy similar changes in bromosulphthalein clearance may be related to reduced binding sites for bromosulphthalein in the liver caused by increased circulating oestrogens. Induction of ketosis resulted in a significant hypoglycaemic (P < 0.01), ketotic (P < 0.001) state compared with well-fed twin-pregnant ewes. These changes could be correlated with the severity of the clinical signs, together with a significant rise in plasma urea (P < 0.001) and NH3 (P < 0.05) concentrations. Again, the return of most of these values to normal by the first week of lactation lends support to the reversibility of hepatic lesions caused by fatty infiltration of the liver. The severity of this condition in naturally occurring cases suggests that factors other than undernutrition may be contributory, such as the general body condition of the ewe and glucose metabolism by the liver, including the conversion of propionate to glucose.

Pancreatic islet transplantation ameliorates the effect of diabetes on retinal capillary endothelial cell kinetics

Perturbations in capillary endothelial cell function are early events in the pathogenesis of diabetic retinopathy. We used tritiated thymidine autoradiography to study the turn-over rate of retinal capillary endothelial cells in retinovascular preparations from normal, untreated diabetic and diabetic mice treated with pancreatic islet-cell transplants. Capillary endothelial cell turnover was significantly increased in poorly controlled diabetes and this increase was reduced by islet-cell transplantation. The prevention of excessive endothelial cell replication by tight control of hyperglycemia may help prevent the characteristic structural changes of diabetic microangiopathy, such as basement membrane accumulation.

Enhanced resistance of anaerobic rumen fungi to the ionophores monensin and lasalocid in the presence of methanogenic bacteria

The presence of Methanobrevibacter smithii altered the susceptibility of the anaerobic fungi Neocallimastix frontalis and Piromonas communis to the carboxylic ionophores monensin and lasalocid. The ionophores depressed growth (measured by chitin accretion), the uptake of glucose and the production of H2, formate and acetate by the fungi growing axenically in semi-solid medium. In the presence of M. smithii, the sensitivity of the fungi to monensin and lasalocid was decreased. For example, the uptake of glucose by N. frontalis strain RE1 in the culture was reduced to 50% of the control value by monensin at 0.5 microgram/ml. In the presence of M. smithii strain PS, approximately three times as much monensin was needed to bring about the same effect. In similar tests, the sensitivity of strain RE1 to lasalocid was decreased about nine-fold in the presence of M. smithii. The effect was not observed if the methanogens were killed by autoclaving before inoculation. It is suggested that the enhanced resistance to ionophores in the presence of M. smithii is a consequence of changes in the energy metabolism of the fungi growing in co-culture.

Modified assay for true and apparent metabolisable energy based on tube feeding

1. To improve the accuracy with which true metabolisable energy (TME) values of feedingstuffs are determined, a modification to the assay based on tube-feeding is proposed. 2. To ensure that the gastrointestinal tracts of the experimental birds are as empty as possible at the start of the assay it is recommended that the normal food is withdrawn 48 h before tube-feeding. 3. In order to partly alleviate the effects of starvation, all birds are given two doses of 25 g glucose (as an aqueous solution) about 40 and 16 h before tube-feeding. Birds, from which endogenous energy losses are to be derived, are fed 50 g glucose rather than given no food. 4. All birds are given 50 ml water by tube about 32 h after feeding to overcome any effects induced by low water intake. 5. A comparison of the two procedures with 8 feedingstuffs showed that the mean coefficient of variation was reduced from 5.5% to 1.5% for TME and from 4.7% to 1.8% for TME.

Intestinal absorption of glucose in rats after continuous challenge with larvae of Nippostrongylus brasiliensis

The rate of glucose absorption and metabolism and the associated fluid transfer of the small intestine of rats was measured in vitro using an everted sac technique after daily doses of 0, 5, 25 or 225 infective larvae of Nippostrongylus for periods of one to five weeks. Though there were occasional significant changes in the physiology of the intestine there were no obvious patterns or trends with respect to time at any infection level. This differs from the response after a single infection. The possible role of immune adaptation and reduced immunogenicity of the worms during repeated infections is considered.

Plasma glucose levels in the peri-operative period in children

Peri-operative plasma glucose levels were studied in one hundred children under 5 years of age and under 20 kg. All underwent procedures of less than 30 minutes. Of 32 cases under the third percentile for weight, ten developed low plasma glucose during the pre-operative and/or postoperative phase. This occurred despite receiving 5% dextrose by mouth 4 hours before induction. Even in children of normal weight there was a low incidence of peri-operative hypoglycaemia. Routine intravenous glucose-containing fluids are thus recommended during the peri-operative period.

Pre-operative starvation in children. The role of alanine in blood glucose homeostasis

Ninety-two children aged between 8 months and 8 years were fasted overnight prior to surgery. Plasma glucose and alanine concentrations were measured after the induction of anaesthesia. Of 30 children under four years, 23% had plasma glucose concentrations less than 3.3 mmol/litre. Underweight children were particularly at risk. The mean plasma alanine was low (0.17 mmol/litre) indicative of a shortfall in this essential substrate for gluconeogenesis. This probably reflects the greater obligatory glucose need of young children relative to their body protein mass.

Intestinal glucose absorption in rats after secondary infections with Nippostrongylus brasiliensis

A challenge infection of Nippostrongylus brasiliensis in immune rats resulted in an earlier onset of intestinal glucose malabsorption and increased glucose metabolism compared with rats receiving a primary infection. Intestinal absorption and metabolism recovered to control levels earlier during a secondary infection. The pattern of changes in absorption and metabolism was probably related to host immunological activity.

Effect of gel fibre on gastric emptying and absorption of glucose and paracetamol

To determine the part played by altered gastric emptying in the modification of glucose absorption by gel fibres, glucose tolerance tests were done in seven healthy volunteers with and without the addition of pectin to the ingested glucose solution and after pharmacological inhibition of gastric emptying with propantheline. Compared with the controls, pectin significantly reduced blood-glucose. Propantheline had a similar but more pronounced effect. Pectin and guar gum did not substantially alter glucose tolerance in a patient who had had total gastrectomy. In a further investigation, gastric emptying and paracetamol absorption were studied simultaneously in fourteen subjects. In eight of these the study was repeated after addition of guar gum and pectin to the ingested paracetamol. Both gastric emptying and paracetamol absorption were slower after gel fibre but the total absorption of the drug, reflected in urinary recovery, was not significantly reduced. The results suggest that the effects of guar gum and pectin on glucose tolerance and paracetamol absorption could be due simply to alteration in the rate of gastric emptying.

A preparation for the study of muscle metabolism during rest and activity

A method for the investigation of metabolism in the isolated rat extensor digitorum longus muscle has been described. This muscle was shown to be suitable for investigations of skeletal muscle metabolism during rest and activity.

The influence of premedication, anaesthesia, age and weight on glucose uptake into human isolated skeletal muscle

The effect of the anaesthetic procedures and of the sex, age and weight of each patient on glucose uptake and glycogen content of human skeletal muscle has been studied in vitro in the presence and absence of insulin. Statistical analysis indicated that the relationships between age and both glucose uptake and the response to insulin were significant, older patients in general having higher uptakes. The blucose uptake was highly correlated with the three obesity indices (ponderal index, body mass index and percentage of the ideal weight). The anaesthetic agents had no significant effect on glucose uptake. The choice of premedication appeared to have a small effect on the basal glucose uptake level, but as the choice of premedication was also age related and age itself was a significant factor, this effect may not be of importance. It is concluded that the age and the degree of obesity of the patients ought to be taken into account when studying samples of human muscle.