Plasma Blood Glucose Concentrations Research Articles

Effects of whole cottonseeds on milk yield, milk composition, and blood components of dairy cows in hot weather

Sixteen multiparous Friesian cows, 70–140 days post partum, were allotted to two groups of eight cows, according to calving date, lactation number and daily yield, and assigned randomly to one of two diets in a crossover design experiment. The two experimental diets were concentrate, containing either 20% whole cottonseeds and 13% soya bean meal or 14% cottonseed meal and 18.5% soya bean meal, plus a mixture of maize silage and straw in the proportions 8:1 (fresh weight) ad libitum. The concentrate was offered individually, in two equal meals daily at 0.4 kg kg −1 of milk produced, and the mixture of maize silage and straw was offered ad libitum once daily on a group basis. The experimental period lasted from 10 June to 4 August 1993, and the cows were housed in an open lot. Dry matter intake, milk protein content and yield, as well as content of milk lactose, total solids and solids not fat were not significantly affected by the diet. In contrast, whole cottonseeds supplementation increased actual milk yield (25.1 vs. 23.1 kg day −1; P < 0.05), 4% fat-corrected milk yield (25.0 vs. 21.5 kg day −1; P < 0.05), milk fat content (3.98 vs. 3.56%; P < 0.05) and milk fat yield (1.0 vs. 0.82 kg day −1; P < 0.05). No significant differences were observed in blood plasma concentrations of glucose, total protein, urea, sodium, potassium, calcium, phosphorus and magnesium. In contrast, increased concentrations in plasma of triglycerides (18.8 vs. 15.9 mg (100 ml) −1; P < 0.05), cholesterol (225.1 vs. 173.2 mg (100 ml) −1; P < 0.001) and phospholipids (225.6 vs. 169.6 mg (100 ml) −1; P < 0.001) were obtained when the cows were fed on the diet containing whole cottonseeds.

Analytical application of membranes with covalently bound glucose oxidase

Biosensor membranes with glucose oxidase, covalently bound to acetylcellulose carriers activated with urea, were prepared and tested in order to evaluate their application in measuring the glucose concentration in blood serum and plasma. A computer-interfaced measurement and research system was used to obtain data about the characteristics of the constructed biosensors. Stability (less than 7.5% change in sensitivity for 20 days by overnight storage at 25°C), biocompatibility (2.2–2.4% loss of sensitivity after 10 blood samples) and acceptable correlation with conventional methods were found to be the main advantages of the biosensors thus obtained.

Familial and metabolic factors related to blood pressure in Pima Indian children.

High blood pressure, abnormal glucose tolerance, and obesity are frequently associated with each other, but the mechanism of these associations is poorly understood. Studying them in children may help in understanding the pathogenesis of hypertension. Blood pressure, height, weight, and plasma glucose and serum insulin concentrations during a 75-g oral glucose tolerance test were measured in 1,698 Pima Indian children aged 6-17 years who participated in an ongoing epidemiologic study. Weight relative to height was used as an index of obesity. The parents of many of the children were also examined. Fasting and 2-hour glucose and insulin concentrations, adjusted for age, sex, and relative weight, were positively related to systolic blood pressure but not to diastolic blood pressure. Relative weight, 2-hour glucose, and fasting insulin concentrations were independently and significantly associated with systolic blood pressure in a stepwise regression analysis that included age and sex. After parental hypertension was taken into account, maternal but not paternal non-insulin-dependent diabetes mellitus, controlled for the child's relative weight and glucose and insulin concentrations, was significantly associated with higher blood pressure in children. The stronger association with maternal diabetes suggests a greater sharing of environmental factors between mother and child than between father and child, but familial similarities in obesity and glucose and insulin concentrations, the diabetic intrauterine milieu, and shared environmental factors probably all contribute to this association.

Pain Relief Can Reduce Hypoxemia in Distressed Neonates During Routine Treatment Procedures

To determine whether the use of opioids could reduce the hypoxemia and hemodynamic instability associated with routine intensive care procedures in neonates with respiratory distress. Randomized and placebo-controlled study. Physiological, plasma beta-endorphin, cortisol, and glucose responses to routine treatment procedures were studied in 84 mechanically ventilated distressed neonates randomized into groups receiving 1 mg/kg meperidine or 0.9% saline 15 minutes before tracheal suction or routine nursing care. The duration of hypoxemia (transcutaneous partial pressure of O2 < 6.6 kPa (< 50 mm Hg) and/or arterial blood oxygen saturation < 80%) during treatment procedures was significantly longer in the saline group (mean 82 vs 36 seconds, P = .001) and distress quantified by a novel behavioral scoring method was much higher. Changes in arterial blood pressure, heart rate, or plasma beta-endorphin, cortisol, and glucose concentration did not show any statistically significant differences between the groups. Newborns with respiratory difficulties often suffer from hypoxemia during essential treatment procedures. The use of opioid analgesia may reduce the duration of hypoxemia and the associated distress and, therefore, may improve the long-term results of neonatal intensive care.

INFLUENCE OF SOMATOSTATIN ANALOGUE (SMS 201–995, OCTREOTIDE) ON BLOOD PRESSURE IN ADRENOCORTICOTROPHIN (ACTH) TREATED RATS: ROLE OF HYPERINSULINAEMIA IN ACTH HYPERTENSION

1. The hypothesis that adrenocorticotrophin (ACTH)-induced hypertension is a consequence of steroid-induced hyperinsulinaemia was tested using the somatostatin analogue (sandostatin, octreotide) to inhibit insulin release in Sprague-Dawley (SD) rats (n = 41). 2. Octreotide (20 micrograms, twice daily) did not modify blood pressure, plasma glucose, bodyweight, water and electrolyte balance, or organ weights but inhibited insulin secretion in the SD rat. 3. Compared with sham injection, ACTH-treated (0.5 mg/kg per day) SD rats showed an increase in blood pressure (sham 111 +/- 4 mmHg; ACTH 140 +/- 5 mmHg on treatment day 10 (P < 0.01), organ weights, water intake, urine volume, plasma glucose, insulin and sodium concentrations, and decrease of bodyweight and plasma potassium concentration. 4. Systolic blood pressure in rats treated with combined octreotide and ACTH was similar to that in rats on ACTH alone. Plasma insulin concentration was lower in octreotide + ACTH treated rats than with ACTH treatment alone. There were no differences in body or organ weights, plasma glucose, water or electrolyte balance. 5. Octreotide lowered plasma insulin concentration to the normal range but did not modify ACTH-induced hypertension in SD rats. These data do not support the notion that insulin-mediated alterations in blood pressure are a major mechanism for ACTH-induced hypertension in the rat.

The Effect of Hypercarbia on Age-Related Changes in Cerebral Glucose Transport and Glucose-Modulated Agonal Glycolytic Rates

This study examined the effect of hypercarbia on cerebral agonal glycolytic rates and brain lactate accumulation after complete ischemia induced by cardiac arrest. Before cardiac arrest, the blood plasma glucose concentration in seven newborn (113 d postconception; normal gestation, 115 d) and seven 1-mo-old (144 d postconception) piglets was adjusted to a specific value (range, 1 to 64 mM), and then inspired ventilation gases were changed to 10:50:40 CO2:O2:N2 for 20 min. The agonal glycolytic rate was measured by monitoring the rate of cerebral lactate formation in vivo using proton nuclear magnetic resonance spectroscopy, and postmortem brain lactate concentrations were measured biochemically in tissue extracts obtained 40 to 45 min after cardiac arrest. These data were compared with 21 normocarbic piglets of similar age, nine examined as part of the present study and 12 examined previously (Corbett RJT, Laptook AR, Ruley JI, Garcia D: Pediatr Res 30:579-586, 1991). There was a nonlinear relationship between the final postmortem brain lactate concentration and preischemia blood plasma glucose concentration that was most prominent in newborn piglets and previously had gone unnoticed. When analyzed using a steady-state model for glucose transport, this relationship revealed that normocarbic newborns had a lower preischemia affinity constant for the transport mechanism for glucose (2.8 +/- 1.5 mM) and lower cerebral glucose utilization rate relative to transport rate (0.12 +/- 0.04), compared with 1-mo-olds (4.5 +/- 1.4 mM and 0.30 +/- 0.03, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Comparative efficacy of flunixin, ketoprofen, and ketorolac for treating endotoxemic neonatal calves

Summary Saline (0.9% NaCl) solution or 1 of 3 nonsteroidal anti-inflammatory drugs (nsaid) was administered iv to 5 neonatal calves 15 minutes after the start of a 3-hour iv infusion of Escherichia coli lipopolysaccharide (lps; 2 µg/kg/h). Four additional calves were given a 3-hour iv infusion of saline solution alone. Clinical attitude, mean arterial blood pressure, pcv, wbc, and plasma lactate, glucose, and eicosanoid concentrations (thromboxane B2, 6-keto-PGF1α) were monitored for 12 hours. Flunixin meglumine (1.1 mg/kg of body weight, iv), ketoprofen (2.2 mg/kg, iv), and ketorolac tromethamine (1.1 mg/kg, iv) each ameliorated the clinical signs of endotoxemia and lps-induced lacticemia, but failed to significantly alter the degree of leukopenia or hypoglycemia associated with infusion of lps. Although the 3 nsaid prevented eicosanoid production, they provided only partial protection against lps-induced hypotension. Each nsaid modified the response to lps, but none was clearly superior to the others in modulating the clinical signs or physiologic alterations induced by infusion of lps in neonatal calves.

Embryonic Viability and Metabolism in Turkey Lines Selected for Egg Production or Growth

Lines of turkeys selected genetically for rapid growth or egg production and their respective randombred control populations were examined for physiological factors influencing their hatchability. Hatchability of fertile eggs was improved (P ≤ .05) in the growth line but not in the egg production line when compared with randombred control populations. Embryonic mortality of both selected lines was lower during the 1st wk of incubation but higher during pipping than that observed for the mortality of the randombred control embryos. Eggshell conductance constants were lower (P ≤ .05) in genetically selected lines compared with constants for eggs of the randombred control strains, which suggests that embryos from selected lines have less access to oxygen. Thus, genetic selection regardless of whether for growth or egg production reduced oxygen consumption during external pipping and for hatched poults, so the reduction cannot be attributed specifically to growth or egg production. Metabolic rate as measured by oxygen consumption during external pipping and posthatch was reduced (P ≤ .05) in the embryos of the selected lines compared with controls. Thus, oxygen availability through eggshells prior to pipping may be vital in determining survival rates of late embryos. Lower oxygen consumption would cause embryos to rely more on stored glycogen for energy during pipping. Hepatic and cardiac glycogen stores and blood plasma glucose concentrations indicated the embryos of growth and egg production lines had less (P ≤ .05) stored glycogen than control embryos. The data suggest that there may be a relationship between carbohydrate accrual prior to pipping, its utilization during pipping, and subsequent embryonic survival during pipping and hatching among the lines and that these differences may be associated with the genetics of growth or egg production.

Cerebral acid buffering capacity at different ages measured in vivo by 31P and 1H nuclear magnetic resonance spectroscopy.

Cerebral acidosis occurring during ischemia has been proposed as one determinant of tissue damage. Newborn animals appear to be less susceptible to ischemic tissue damage than adults. One possible component of ischemic tolerance could derive from maturational differences in the extent of acid production and buffering in newborns compared to adults. The purpose of this study was to measure the dependency of acid production on the blood plasma glucose concentrations and acid buffering capacity of piglets at different stages of development. Complete ischemia was induced in 29 piglets ranging in postconceptual age from 111 to 156 days (normal term conception, 115 days). Brain buffering capacity during the first 30 min of ischemia was quantified in vivo, via 31P and 1H nuclear magnetic resonance (NMR) spectroscopy, by measuring the change in intracellular brain pH for a given change in the concentration of compounds that contribute to the production of hydrogen ions. Animals from all four age groups showed a similar linear correlation between preischemia blood glucose concentration and intracellular pH after 30 min of ischemia. For each animal the slope of the plot of intracellular pH versus cerebral buffer base deficit was used to calculate the buffer capacity. Using data obtained over the entire 30 min of ischemia, there was no difference in the mean buffer capacity of the different age groups, nor was there a significant correlation between buffer capacity and age. However, there was a significant increase in buffer capacity for the intracellular pH range 6.6-6.0, compared to 7.0-6.6, for all age groups. No significant differences in buffer capacity for these two pH ranges were observed between any of the age groups. Acid buffering capacity was also measured by performing pH titrations on brain tissue homogenized in the presence of inhibitors of glycolysis and creatine kinase. Plots of homogenate pH versus buffer base deficit showed a nonlinear trend similar to that seen in vivo, indicating an increase in buffer capacity as intracellular pH decreases. A comparison of newborn and 1-month-old brain tissue frozen under control conditions or after 45 min of ischemia revealed no differences that could be attributed to age and a slight decrease in buffer capacity of ischemic brain compared to control brain tissue homogenates. There was no difference between the brain buffering capacity measured in vivo using 31P and 1H NMR and that measured in vitro using brain homogenates.

Renal vascular hypertension does not lead to hyperinsulinemia in Sprague-Dawley rats.

The effect of renal vascular hypertension on blood pressure and plasma glucose, insulin, and triglyceride concentration was studied in Sprague-Dawley rats. Three weeks after the induction of renal artery sterosis, mean (+/- SEM) blood pressure was significantly greater (153 +/- 3 v 117 +/- 2 mm Hg, P less than .001) compared with that in sham-operated rats. However, the two groups were similar in terms of plasma glucose (140 +/- 3 v 140 +/- 2 mg/dL), insulin (27 +/- 3 v 23 +/- 2 microU/mL), and triglyceride (89 +/- 8 v 95 +/- 6 mg/dL) concentrations. Furthermore, blood pressure increased to a similar degree in the two groups of rats (22 +/- 4 v 24 +/- 2 mm Hg), as did plasma insulin (47 +/- 5 v 44 +/- 4 microU/mL) and triglyceride (407 +/- 50 v 381 +/- 46 mg/dL) concentrations, after 2 weeks of a high-fructose diet. These data indicate that experimental induction of renal vascular hypertension in normal rats was not associated with an increase in either plasma insulin or triglyceride concentration. Furthermore, the response of rats with renal vascular hypertension to a high-fructose diet was similar to that of the sham-operated group. These data support the view that hypertension, per se, does not lead to hyperinsulinemia and hypertriglyceridemia in normal rats.

Supplementation of Dairy Cow Diets with Calcium Salts of Long-Chain Fatty Acids and Nicotinic Acid in Early Lactation

Forty multiparous Holstein cows were assigned to one of four treatments 15 d postpartum according to milk yield during wk 2 postpartum to examine the effects of supplementing niacin, Ca salts of long-chain fatty acids, and their interaction. Treatments were control, niacin (12g/d), Ca salts of long-chain fatty acids (3% of dietary DM), or a combination of niacin and Ca salts. On d 99 postpartum, all cows were fed the control treatment for 2 wk to evaluate residual effects. Milk and FCM yields, blood plasma NEFA and β-hydroxybutyrate concentrations, and apparent total tract hemicellulose digestibility were increased; milk protein percentage, milk SNF percentage, and blood plasma glucose concentrations were reduced by treatments containing the Ca soaps. Niacin supplementation increased milk protein content and yield but reduced blood plasma β-hydroxybutyrate concentration. During the residual period, in which all cows received the control treatment, milk yield and plasma NEFA concentration remained elevated, milk protein and SNF contents remained depressed, and milk fat content was reduced for cows previously supplemented with Ca salts of long-chain fatty acids. Methionine and phenylalanine uptakes by the mammary gland were enhanced by niacin supplementation. Results indicated that dairy cattle in early lactation yielded more milk when their diets were supplemented with Ca salts of long-chain fatty acids and that niacin supplementation increased milk protein content and yield.

Uterine and umbilical blood flows and net nutrient uptake by fetuses and uteroplacental tissues of cows gravid with either single or twin fetuses.

To evaluate the influence of cow breed and number of fetuses on uterine and umbilical blood flows and nutrient fluxes or uterine tissues from gravid cows, surgery was performed on Charolais or Hereford cows with single or twin fetuses at 177 +/- .2 d (mean +/- SEM) after mating. Indwelling catheters were placed in a fetal femoral artery and vein, in an umbilical vein of each fetus, and in a uterine artery and vein of each gravid horn. Deuterium oxide (D2O) was infused into a fetal femoral vein at 183 +/- .3 and 190 +/- .5 d after mating to estimate uterine and umbilical blood flows (liters/minute). Blood oxygen and plasma glucose and lactate concentrations were determined and uterine arterio-venous (A-V) and umbilical venous-fetal arterial (v-a) differences and net uterine and fetal uptakes were calculated. Net utilization by the uteroplacenta was calculated as the difference between uterine and fetal net uptakes. Uterine blood flows were lower (P less than .01) in Hereford (4.80 +/- .28) than in Charolais (7.07 +/- .33) and lower (P less than .01) per fetus in cows with twin fetuses (5.22 +/- .34) than in cows with a single (6.65 +/- .28) fetus. Umbilical blood flows were greater for single than for twin fetuses. Fetal oxygen and glucose net uptakes averaged 57 and 12%, respectively, of net uteroplacental utilization. Lactate was released from uteroplacental tissues to fetal (42%) and maternal circulations (58%). Fetal oxygen uptakes tended to be less for twin fetuses (P = .08) than for a single fetus.(ABSTRACT TRUNCATED AT 250 WORDS)

The Effect of Age on Glucose-Modulated Cerebral Agonal Glycolytic Rates Measured In Vivo by 1H NMR Spectroscopy

The purpose of this study was to investigate the effect of plasma glucose concentration on cerebral agonal glycolytic rates in piglets of different ages. Twenty-four piglets were divided into four different age groups corresponding to 113, 121, 128, and 145 d postconception (normal gestation = 115 d). For each group the agonal glycolytic rate was measured by monitoring the rate of cerebral lactate accumulation after total ischemia. Ischemia was induced by cardiac arrest, and the rate of lactate formation was measured in vivo using proton nuclear magnetic resonance spectroscopy. Before cardiac arrest, the blood plasma glucose concentration for individual piglets was adjusted to a specific value in the range 1-30 mM. The dependence of agonal glycolytic rate upon blood glucose concentration was analyzed for each age group, using the Michaelis-Menten equation to evaluate Vmax, the maximal rate of glucose utilization, and Km the concentration of plasma glucose at which the half maximal rate of utilization occurs. Vmax for the two youngest age groups of piglets had significantly different (p less than 0.05) values compared with each other (1.38 +/- 0.17 and 1.92 +/- 0.64 mumol.g-1.min-1, respectively) and with the two older groups of animals (2.99 +/- 0.52 and 3.42 +/- 0.65 mumol.g-1.min-1, respectively). The Km values determined for the two youngest age groups (0.79 +/- 0.70 and 1.79 +/- 0.33 mM, respectively) also were significantly lower than for the two older age groups (4.96 +/- 2.90 and 4.82 +/- 2.96 mM, respectively). We conclude that throughout the first 2 wk of life there are marked increases in the cerebral glycolytic capacity.(ABSTRACT TRUNCATED AT 250 WORDS)

Abnormalities of carbohydrate and lipid metabolism in Dahl rats.

Plasma glucose, insulin, and triglyceride concentration, blood pressure, and insulin action on isolated adipocytes were determined in weight-matched Sprague-Dawley, Dahl salt-resistant, and Dahl salt-sensitive rats. Blood pressure and plasma glucose concentrations were not significantly different in the three groups. However, Dahl salt-sensitive rats had significantly higher plasma insulin (39 +/- 2 microunits/ml) and triglyceride (213 +/- 11 mg/dl) concentrations than did Sprague-Dawley rats (27 +/- 2 microunits/ml and 101 +/- 6 mg/dl, respectively). Values for insulin (34 +/- 4 microunits/ml) and triglyceride (159 +/- 11 mg/dl) were intermediate in Dahl salt-resistant rats. In contrast, maximal insulin-stimulated glucose transport was significantly lower in adipocytes isolated from Dahl salt-sensitive as compared with Sprague-Dawley rats (400 +/- 16 versus 523 +/- 14 fl/cell/sec), with Dahl salt-resistant rats again having intermediate values. However, the ability of insulin to maximally inhibit catecholamine-stimulated lipolysis was similar in all three groups, averaging approximately 20% of the activity present in the absence of insulin. All of these differences were seen when the rats were eating conventional chow and did not change in Dahl rats after 2 weeks of an 8% NaCl diet. On the other hand, the predicted rise in blood pressure took place in Dahl salt-sensitive rats, increasing from 147 +/- 4 to 181 +/- 6 mm Hg.(ABSTRACT TRUNCATED AT 250 WORDS)

Sympathoadrenal control by paraventricular hypothalamic beta-endorphin in hypertension.

The paraventricular hypothalamus regulates autonomic nerve outflow and is innervated with beta-endorphin-immunoreactive nerve terminals. This study examined the effects of beta-endorphin microinjected into the paraventricular hypothalamus on blood pressure, heart rate, and plasma catecholamine and glucose concentrations in conscious, unrestrained spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) rats at the age of about 9 weeks. Thirty minutes after paraventricular hypothalamic injection of [125I] beta-endorphin (3.5 micrograms), most of the recovered radioactivity was detectable within +/- 0.5 mm from the injection site in the coronal, sagittal, and horizontal planes. Unilateral paraventricular hypothalamic injections of beta-endorphin (1 and 0.1 microgram/0.1 microliter) increased blood pressure and heart rate in both strains in a dose-independent manner with significantly greater increases in SHR. Plasma catecholamine and glucose concentrations were measured 15, 30, and 60 minutes after beta-endorphin injection. Norepinephrine concentrations were not significantly altered in WKY rats but increased in SHR. Epinephrine concentrations increased in both strains with significantly greater increases in SHR. Increases in catecholamine concentrations were not dose-related. Glucose concentrations also increased in both strains with significantly greater increases in SHR only at the lower dose. Ganglionic blockade with pentolinium significantly reduced beta-endorphin-induced pressor and tachycardiac responses in SHR. Pretreatment of the paraventricular hypothalamus with naltrexone (1.1 micrograms) in SHR blocked the initial pressor and tachycardiac responses to beta-endorphin (0.1 microgram) and blunted increases in epinephrine and glucose levels. When the animals were anesthetized with alpha-chloralose 2-5 days after the study in conscious animals, there were no differences in blood pressure or heart rate between strains after beta-endorphin (0.1 microgram) injection. The results indicate that conscious SHR show enhanced cardiovascular and sympathoadrenal responses to beta-endorphin injected into the paraventricular hypothalamus, suggesting that alterations in the activity of the paraventricular hypothalamic beta-endorphin system can modulate the development of hypertension in SHR.

Influence of Diet-Mediated Maternal Thyroid Alterations on Hatchability and Metabolism of Turkey Embryos

Large White turkey breeder hens from a strain exhibiting poor hatchability were fed thyroid-altering diets. The following dietary treatments were fed to randomized groups of hens for 15 wk of egg laying: 1) 16.5% protein turkey breeder diet (control), 2) the control diet containing 2.1 ppm supplemental iodine, 3) the control diet containing .1% thiouracil, and 4) the control diet containing .5 ppm triiodothyronine (T3). Blood samples were taken from hatching embryos from hens fed each diet. Embryonic hearts and livers were weighed prior to and during pipping as well as after hatching. Blood plasma was analyzed for thyroxine (T4), T3, and glucose. Livers were assayed for glucose-6-phosphatase activity. Supplemental maternal dietary iodine elevated embryonic T4 concentrations prior to pipping. Dietary T3 and iodine increased hepatic glucose-6-phosphatase activity and blood plasma glucose concentration prior to pipping. Feeding thiouracil increased embryonic liver weights but decreased heart and body weights. Blood plasma T4 was elevated in embryos from hens fed thiouracil but blood glucose levels were depressed because of a lack of increased glucose-6-phosphatase activity. Feeding iodine decreased the enzyme activity at internal pipping. It is suggested from the data that maternal thyroid metabolism may influence hatchability via embryonic thyroid and carbohydrate metabolism during hatching.

Effects of sodium carbonate on milk yield, milk composition and blood components of dairy cows in hot weather

Sixteen Friesian cows, 55–150 days postpartum, were allotted to two groups of eight cows, according to calving date, lactation number and daily milk yield, and assigned randomly to one of two diets in a crossover design experiment. The two experimental diets were concentrate containing 0 or 1.2% sodium carbonate, plus sorghum silage. The concentrate was offered individually, in two equal meals daily at 0.5 kg kg −1 of milk produced, and the sorghum silage was offered ad libitum once daily on a group basis. The experimental period lasted from 14 June to 8 August 1989, and the cows were housed in an open lot, without shade. Dry matter intake, actual milk yield, milk protein content and yield, as well as content of milk lactose and milk solids excluding fat were not significantly affected. In contrast, sodium carbonate supplementation increased milk fat content (4.17 vs. 3.74%; P < 0.01), milk fat yield (1.10 vs. 0.97 kg day −1; P < 0.05), 4% fat-corrected milk yield (27.0 vs. 24.9 kg day −1; P < 0.05) and milk total solids content (13.17 vs. 12.71%; P < 0.05). No significant differences were observed in blood plasma concentrations of glucose, total protein, urea, acetate, β-hydroxybutyrate, free fatty acids, sodium and potassium. In contrast, the plasma concentration of triglycerides was higher (35.4 vs. 27.8 mg per 100 ml; P < 0.01) when the cows were fed on the diet containing sodium carbonate.

Effects of caffeine with repeated dosing

We have recently demonstrated dose-dependency of caffeine metabolism under multiple dosing conditions. Whether there are persistent pharmacodynamic actions of caffeine under such circumstances is the focus of this report. Nine healthy subjects were given, in randomized 5 day blocks, placebo, 4.2 (low) and 12 (high) mg.kg-1.day-1 of caffeine in 6 divided doses. After 5 days, complete tolerance developed to the effects of caffeine on blood pressure, heart rate and plasma glucose concentrations. The 24-h area under the curve (AUC) for plasma norepinephrine and the AUC for the total sum of free fatty acids (FFA) both demonstrated a trend to increase with the high dose caffeine treatment. When the AUC for norepinephrine was split into 12 h time periods, a significant difference between the placebo and the high dose treatment block was seen. We conclude that regular consumption of 12 mg.kg-1 of caffeine per day (equivalent to approximately 6 to 11 cups of coffee per day) may produce pharmacodynamic effects not completely compensated for by the development of tolerance. Mechanisms of tolerance may be overwhelmed by the nonlinear accumulation of caffeine and other methylxanthines in the body when caffeine metabolism becomes saturable.

Effects of Sodium Carbonate on Milk Yield, Milk Composition, and Blood Components of Dairy Cows in Early Lactation

Eighteen multiparous Friesian cows were paired according to lactation number and expected calving date and assigned randomly to one of two diets in a crossover design experiment to study effects of sodium carbonate on milk yield, milk composition, blood metabolites plus Na, and K in early lactation. Diets were concentrate containing either 0 or 1.2% sodium carbonate (as fed) for ad libitum intake plus 7.0kg of wet brewers grains and 5.5kg of long-stemmed alfalfa hay per cow daily. Dry matter intake, milk yield, milk protein percentage and yield, and percentages of milk lactose and milk SNF were not significantly affected. Compared with the control diet, the sodium carbonate treatment increased milk fat percentage (3.98 vs. 3.53%) and yield (1.23 vs. 1.07 kg/d), 4% FCM yield (30.9 vs. 28.2 kg/d) and milk total solids (12.47 vs. 12.04%). No significant differences were observed in blood plasma concentrations of glucose, CP, urea, acetate, β-hydroxybutyrate, triglycerides, FFA, Na, or K when sodium carbonate was added to diets for early lactation cows.

Early postnatal dexamethasone therapy in premature infants with severe respiratory distress syndrome: A double-blind, controlled study

To determine whether early (less than or equal to 12 hours) postnatal dexamethasone therapy would facilitate removal of the endotracheal tube and improve outcome in premature infants with severe respiratory distress syndrome, we conducted a double-blind, controlled study of 57 infants whose birth weights were less than 2000 gm. The placebo (n = 29) and treated (n = 28) groups were comparable in birth weight (mean +/- SD: 1273 +/- 323 vs 1318 +/- 359 gm), gestational age (30.1 +/- 2.1 vs 30.8 +/- 2.7 weeks), postnatal age (8.7 +/- 3.1 vs 8.5 +/- 3.1 hours), and pulmonary function at the start of the study. The dose of dexamethasone was 1.0 mg/kg/day for 3 days and then was progressively decreased for 12 days. Infants in the dexamethasone group had significantly higher pulmonary compliance, tidal volume, and minute ventilation, and required lower mean airway pressure for ventilation than infants in the placebo group. The endotracheal tube was successfully removed from more infants in the dexamethasone group (16/28 vs 8/29; p less than 0.025). Nineteen infants (65%) in the placebo group and 11 (39%) in the dexamethasone group (p less than 0.05) had lung injuries. Dexamethasone therapy was associated with a temporary increase in blood pressure and plasma glucose concentration and a delay in somatic growth. We conclude that early postnatal dexamethasone therapy improves pulmonary status, facilitates removal of the endotracheal tube, and minimizes lung injuries in premature infants with severe respiratory distress syndrome.