Biomedical subjects

T Wensing

Publications and source records attributed to T Wensing.

At least 19 recordsLinked to original sources

PubMed1999

Hepatic fatty acid composition in periparturient dairy cows with fatty liver induced by intake of a high energy diet in the dry period.

The present study compared the hepatic fatty acid composition of cows that were fed a high energy diet during the dry period to induce fatty liver after parturition with that of control cows. Treated cows had higher concentrations of plasma nonesterified fatty acids as a result of greater lipolysis after parturition than did control cows; consequently, the treated cows accumulated greater amounts of triacylglycerols in the liver. Before parturition, treated cows had lower percentages of oleic acid and higher percentages of linoleic acid than did control cows, but percentages of other fatty acids were similar for both groups. After parturition, percentages of each fatty acid were changed substantially, particularly the four major fatty acids (palmitic, stearic, oleic, and linoleic acids). For treated cows, the percentages of palmitic and oleic acids were higher at 0.5 wk after parturition than at 1 wk before parturition; percentages of stearic and linoleic acids decreased. Unlike treated cows, the percentages of both oleic and linoleic acids in the control cows did not change during that time. Moreover, we found that when lipolysis decreased, as indicated by lower plasma nonesterified fatty acid concentrations, the percentages of each fatty acid gradually rebounded toward the concentrations measured before parturition; this observation indicates that the shift in hepatic fatty acid composition is influenced by lipolysis. The increased lipolysis after parturition led to a vast increase in the hepatic triacyglycerol concentration and to a shift in hepatic fatty acid composition.

3-Hydroxybutyric Acid↗

PubMed1999

Effect of fatty liver on hepatic gluconeogenesis in periparturient dairy cows.

The purpose of this study was to compare the hepatic enzyme activities of gluconeogenesis between control cows and experimental cows that had been overfed during the dry period to induce fatty liver postpartum. Blood and liver samples were collected 1 wk before and 0.5, 1, 2, and 3 wk after parturition. Before parturition, neither the serum nonesterified fatty acid nor the liver triacylglycerol concentration differed between the two groups. After parturition, these variables were higher in experimental cows than in control cows. Liver glycogen was higher at 1 wk before parturition in experimental cows; sharply decreased after parturition in both groups; and, at 1 wk after parturition, was lower in experimental cows than in control cows. In the liver, activities of phosphoenolpyruvate carboxykinase were significantly lower at 1 wk before and at 0.5 and 2 wk after parturition in experimental cows; in addition, the activities tended to be lower at 1 wk after parturition. Activities of fructose 1,6-bisphosphatase tended to be lower, but activities of glucose 6-phosphatase tended to be higher, at 0.5 wk after parturition in experimental cows than in control cows. Our results suggest that, in fatty infiltrated liver, the rate of gluconeogenesis is not optimal, which results in prolongation of lipolysis, particularly during the first weeks after parturition.

Animals↗

PubMed1998

Reversible translocation of CTP:phosphocholine cytidylyltransferase from cytosol to membranes in the adult bovine liver around parturition.

The key regulatory enzyme of phosphatidylcholine (PC) synthesis, CTP:phosphocholine cytidylyltransferase (CT), is known to be activated in vitro by translocation from soluble to particulate fractions of the cell. In the present study the periparturient cow was chosen as a model to investigate whether translocation of CT can contribute to the regulation of PC synthesis in vivo. Between parturition and 1.5 weeks post-partum, the cytosolic CT activity in the liver of the adult animal decreased 1.9-fold, and this correlated with a 1.8-fold increase in microsomal CT activity. At that time, microsomal CT activity started to decline again whereas the cytosolic activity rose concomitantly until both activities reached their pre-partum values at 8 weeks post-partum. The activities of soluble and membrane-bound CTP:phosphoethanolamine cytidylyltransferase (ET), the analogous enzyme in the CDP-ethanolamine pathway, did not change significantly throughout this period. Whereas hepatic PC concentrations declined until about 2 weeks post-partum and thereafter gradually returned to pre-partum levels, the PC levels in very-low-density-lipoproteins, started to rise 2 weeks after the partus reaching a maximum of 219% of the original value at 8 weeks post-partum. These results strongly suggest that there is a reversible redistribution of CT between cytosol and membranes in a physiologically relevant animal model, supporting the concept that translocation of CT is occurring in vivo.

Animals↗

PubMed1998

Evaluation of a milk test for detection of subclinical ketosis.

This study included 190 lactating cows from eight dairy farms and was designed to investigate the sensitivity and specificity of a milk test (Ketolac) for detecting subclinical ketosis in dairy cattle. Blood and milk samples were collected between 38 and 50 days post partum. At a beta-hydroxybutyric acid concentration in blood of 1.2 mmol/L, the prevalence of ketosis was 14%. A Response Operator Characteristic curve was drawn for two milk test values: 100 mumol/L and 200 mumol/L. Assessment of several beta-hydroxybutyric acid cut-off values in blood showed that when 100 mumol/L on the Ketolac milk test was defined positive, the most desirable sensitivity-specificity combination was achieved. This milk test can be routinely used to screen a herd for subclinical ketosis.

Animals↗

PubMed1998

Weaning and the weanling diet influence the villous height and crypt depth in the small intestine of pigs and alter the concentrations of short-chain fatty acids in the large intestine and blood.

Effects of weaning pigs to different diets have been investigated in terms of the changes in the small intestinal morphology, and in the absorption of short-chain fatty acids (SCFA) and sodium from the large intestine. One piglet from each of six litters containing nine pigs was sampled on the day of weaning; the other eight piglets were divided into four equal groups and fed different diets as follows: unweaned, weanling diet, or sow's milk at high or low level. Four and seven days after weaning, measurements of the intestinal tissue and contents were made; the plasma concentrations of SCFA, aldosterone and sodium were also measured. The villous height in the small intestine was highest in the unweaned group and greater in the high milk group than in either the weanling diet or low milk group (P < 0.001). Apparently, villous atrophy was due more to the level of feed intake than to the composition of the diet. The concentrations of SCFA in the large intestine and portal blood were highest in the weanling diet group and lowest in the low milk group. The low milk group tended to have higher blood concentrations of aldosterone (P = 0.15), which may have compensated for the low concentrations of SCFA in maintaining a higher percentage of dry matter in the intestine. Pigs fed weanling diet may use the energy from the SCFA to maintain a body weight comparable to that of pigs fed milk at a low level.

Aldosterone↗

PubMed1998

Effects of high calcium intake on fat digestion and bile acid excretion in feces of veal calves.

We tested the hypothesis that apparent digestibility of fat by veal calves is determined by the participation of bile acids in the process of fat absorption and is, therefore, negatively associated with bile acid excretion in feces. Veal calves were fed milk replacers that contained whey protein and either a low (5.2 g of calcium/kg of air-dried diet) or high (12.4 g of calcium/kg of air-dried diet) concentration of calcium. The high calcium milk replacer contained extra calcium in the form of calcium formate. Final body weight was not significantly influenced by diet after the milk replacers had been fed for 27 wk. Feces were quantitatively collected during wk 23 of the trial. The high calcium milk replacer reduced apparent fat digestibility by 5.6 percentage units and increased bile acid excretion in feces by 90% compared with the low calcium milk replacer. The extra calcium intake decreased apparent absorption of magnesium and phosphorus. We proposed that a high intake of calcium by veal calves would increase the amount of insoluble calcium, magnesium, and phosphate complexes in the intestinal lumen, which, because of the binding of bile acids, would exclude bile acids from the process of fat digestion and inhibit reabsorption of bile acids. As a result, fat digestion is impaired, and bile acid excretion in feces is enhanced. The complex formation in the ileal lumen also explains why high calcium intake reduces magnesium and phosphorus absorption in veal calves.

Absorption↗

PubMed1998

Effect of overfeeding during the dry period on regulation of adipose tissue metabolism in dairy cows during the periparturient period.

During the dry period, cows were either fed restricted amounts or were overfed to study lipolytic rates in adipose tissue. Higher lipolytic rates can result in greater accumulation of triacylglycerols in liver and, subsequently, hepatic lipidosis. Adipose tissue was biopsied at -1, 0.5, 1, 2, and 3 wk from parturition. The basal in vitro lipolytic rate was measured as well as the lipolytic rate as affected by the addition of noradrenaline, 3-hydroxybutyrate, or glucose. Liver was biopsied to quantify triacylglycerol concentrations. Blood was collected to determine insulin and nonesterified fatty acid concentrations. Basal in vitro lipolytic rates at -1 and 0.5 wk were lower in overfed cows. Lipolytic rate was enhanced in both groups of cows when noradrenaline was added, but rates at -1 and 3 wk tended to be higher in overfed cows than in cows that were fed restricted amounts. After the addition of 3-hydroxybutyrate or glucose in vitro, lipolytic rates tended to be higher in overfed cows. Liver triacylglycerol concentration was higher in overfed cows at 0.5 and 1 wk. Plasma insulin concentration tended to be higher in overfed cows at -1 wk. Plasma nonesterified fatty acid concentration was higher in overfed cows at 0.5 and 1 wk. Although overfeeding compared with restricted feeding did not significantly alter the in vitro lipolytic response to 3-hydroxybutyrate or glucose, adipose tissue from overfed cows tended to be less inhibited by these substances, which may contribute to higher lipolytic rates in vivo and a greater triacylglycerol accumulation in the liver after parturition.

3-Hydroxybutyric Acid↗

PubMed1998

Role of the large intestine in the pathogenesis of diarrhea in weaned pigs.

OBJECTIVE: To determine whether the large intestine may have a role in counterbalancing the loss of fluid from the small intestine of pigs with diarrhea. ANIMALS: 2 groups of pigs (1 from a specific-pathogen-free herd and 1 from a herd with a history of diarrhea). PROCEDURE: At weaning and 4, 7, 11, and 14 days after weaning, the percentage of dry matter in the large intestinal contents, total and individual concentrations and volatile fatty acids in large-intestinal contents and blood, and concentration of aldosterone in the blood were measured. RESULTS: Large intestinal contents of pigs with diarrhea had a lower percentage of dry matter, lower acetate and butyrate concentrations, and higher propionate concentrations than did those of specific-pathogen-free pigs, and blood of pigs with diarrhea also had lower total volatile fatty acids concentration, higher aldosterone concentration, and lower sodium concentration. CLINICAL RELEVANCE: The large intestine has a role in the pathogenesis of diarrhea in weaned pigs.

Aging↗

PubMed1998

Weaning piglets, microbial fermentation, short chain fatty acids and diarrhoea.

The effect of weaning on the absorptive capacity of the large intestine (LI) of weaned and unweaned pigs for short chain fatty acids (SCFA), sodium, potassium, and water has been determined by perfusion studies. Ligated loops were formed at four sites in the LI. In both groups the rate of absorption of SCFA, sodium and potassium was increased from the proximal to the distal sites, but this increase was not followed by an increase in the absorption of water. It is concluded that unweaned and weaned pigs can absorb SCFA and electrolytes immediately after weaning, but that a period of adaptation is required for the optimal absorption of water. This lower capacity for the absorption of water in the first two weeks after weaning makes the recently weaned pig vulnerable to a loss of fluid from the intestines.

Adaptation, Physiological↗

PubMed1997

Impaired specific immunoreactivity in cows with hepatic lipidosis.

In this study, hepatic lipidosis in cows was experimentally induced by offering an energy surplus during the dry period. Liver triacylglycerol (TAG) was 16% in the experimental group. In the control group fed the same diet in restricted quantities, liver TAG was about 7%. The animals of both groups were vaccinated with tetanus vaccine at Day 3 after parturition. It was demonstrated that the cows with high liver TAG percentages had lower humoral and cellular (P < 0.05) immunological responses compared with the animals with low liver TAG levels at Day 14 after vaccination. The results obtained in the high TAG group support the notion that the frequent occurrence of aspecific infections in cows with hepatic lipidosis may be due to impaired immunoreactivity.

Animals↗

PubMed1997

Effects of pentoxifylline and polymyxin B on the acute-phase-response to Escherichia coli endotoxin in dwarf goats.

The purpose of this study was to assess whether polymyxin B together with pentoxifylline, had beneficial effects on the acute-phase-response to E. coli endotoxin in the dwarf goat (n = 6). Polymyxin B partly neutralizes E. coli endotoxin by forming inactive polymyxin B-lipopolysaccharide (LPS) complexes; pentoxifylline has been reported to suppress the LPS-induced production of tumour necrosis factor (TNF-alpha). E. coli LPS (0.0067 microgram/kg/min over 30 min) induced fever, tachycardia, inhibition of rumen motility, a decline in WBC, lymphopenia, and decreases in plasma zinc and iron concentrations. Most of the haematological, blood biochemical and clinical effects of E. coli LPS were significantly reduced by polymyxin B pretreatment (0.1 mg/kg/min over 30 min, i.v.). Pentoxifylline (0.3 mg/kg/min over 30 min, i.v.) did not reduce the clinical and blood biochemical effects of E. coli LPS, however, it modulated the number of circulating neutrophils. No synergistic effects were observed after i.v. infusion of polymyxin B with pentoxifylline. The lack of synergy may be due to the production and release of pro-inflammatory cytokines other than TNF-alpha.

Acute-Phase Reaction↗

PubMed1997

The effects of dietary soybean versus skim milk protein on plasma and hepatic concentrations of zinc in veal calves.

We assessed the zinc status of veal calves that were fed milk replacers containing either skim milk protein as the sole source of protein or a mixture of skim milk protein and soybean protein. After the milk replacers had been fed for 26 wk, mean body weight gain was 3 kg lower for calves fed the skim milk plus soybean proteins; this decrease was not significant. Inclusion of dietary protein from soybeans versus milk protein alone reduced plasma concentrations of zinc by 43% and reduced hepatic concentrations of zinc by 81%. The impairment of zinc status that was induced by the inclusion of soybean protein was probably caused by its phytate component. The effect of soybean protein on zinc status was rather specific because plasma and hepatic concentrations of copper were unaffected. Despite the high concentration of zinc (142 mg/kg of dry matter) in the milk replacer that contained milk plus soybean proteins, calves displayed a shortage of zinc because their plasma and hepatic concentrations of zinc were significantly reduced.

Animal Nutritional Physiological Phenomena↗

PubMed1996

Changes in liver and fat depots of west African dwarf goats (Capra aegagus hircus) after an infection with T. vivax.

Nine West African dwarf goats (Capra aegagus hircus) were each infected experimentally with 3 x 10(7) Trypanosoma vivax parasites. The changes in the plasma concentration of nonesterified fatty acids (NEFA) were monitored during the infection and the level of hepatic triacylglycerols and glycogen was measured postmortem. During the infection they had higher plasma NEFA concentrations than nine uninfected control goats and at postmortem their total liver triacylglycerol and glycogen contents were found to be increased. These observations suggest that the mobilization of the goats' defense mechanisms against the T. vivax infection induced a more intensive fat mobilization resulting in changes in fat metabolism of the liver.

Adipose Tissue↗

PubMed1996

Higher postpartum hepatic triacylglycerol concentrations in dairy cows with free rather than restricted access to feed during the dry period are associated with lower activities of hepatic glycerolphosphate acyltransferase.

We investigated the activities of hepatic glycerolipid synthesizing enzymes during postpartum fatty liver development in 10 high-producing dairy cows that had free access to feed during the dry period; a parallel group of 8 control cows was fed according to recommended energy requirements. After calving, both test and control cows had free access to feed. In the period of 10-14 wk before calving, voluntary dry matter intake of the test cows was 20.6 kg/d (SEM 0.42); the restricted control cows received 7 kg/d. Postpartum triacylglycerol concentrations in liver biopsies were one- to twofold higher in the test than in the control cows. The higher plasma nonesterified fatty acid (NEFA) concentrations after parturition in the test vs. the control group were probably caused by a more negative energy balance in the test cows, which was associated with a slightly lower postpartum dry matter intake. After calving, hepatic mitochondrial glycerolphosphate acyltransferase (GPAT) activities were significantly lower in the test than in the restricted control cows. A low GPAT activity may divert fatty acids from esterification to beta-oxidation to protect the hepatocytes against further accumulation of triacylglycerols. The activities of hepatic phosphatidate phosphohydrolase, diacylglycerol acyltransferase, and cholinephosphate cytidylyltransferase were not different in the two groups. This study indicates that in cows given free instead of restricted access to feed during the dry period have a postpartum hepatic triacylglycerol accumulation that is mainly determined by a raised hepatic uptake of plasma NEFA.

Alkaline Phosphatase↗

PubMed1995

Lipid metabolism in horses with hyperadrenocorticism.

Lipid metabolism was studied in 21 horses with hyperadrenocorticism. To be included in the study, horses had to have histologic evidence of a pars intermedia adenoma found at necropsy (n = 9), a baseline ACTH concentration greater than 400 pg/ml (n = 6), or a plasma cortisol concentration 2 hours after i.v. administration of 25 IU of ACTH greater than 413 nmol/L (n = 16). Mean +/- SD baseline plasma cortisol concentration was 338 +/- 261 nmol/L (n = 20), mean +/- SD plasma insulin concentration was 97 +/- 54 microU/ml (n = 15), mean +/- SD plasma beta-hydroxybutyrate concentration was 1.8 +/- 1.2 mg/dl (n = 21), and mean +/- SD plasma nonesterified fatty acids concentration was 6.2 +/- 6.4 mg/dl (n = 21). None of the horses had hyperlipemia. Compared with clinically normal horses, horses with hyperadrenocorticism had increased lipolysis and increased ketogenesis. It was concluded that cortisol cannot be the sole factor contributing to insulin resistance in horses with hyperadrenocorticism.

3-Hydroxybutyric Acid↗

PubMed1995

Pentoxifylline pretreatment fails to block the acute-phase response to Escherichia coli endotoxin in dwarf goats.

The purpose of this study was to assess whether pentoxifylline, a drug that can inhibit the production and action of pro-inflammatory cytokines, had beneficial effects on the acute-phase response to E. coli endotoxin in the dwarf goat. First, the effects of 0.5 mg/kg per min pentoxifylline given intravenously over 15 min were examined in five goats. One week later, the clinical changes caused by i.v. injection of E. coli endotoxin (LPS: 0.1 microgram/kg) were determined. This endotoxin induced fever, tachycardia, inhibition of rumen motility, and decreases in plasma zinc and iron concentrations. Three weeks later, the effect of E. coli LPS were again determined immediately after pentoxifylline infusion in the same group of animals. It was concluded that a pharmacological dose of pentoxifylline has no protective effects on the acute-phase response reactions induced by a pyrogenic dose of E. coli LPS.

Acute-Phase Reaction↗

PubMed1995

Laboratory diagnosis of equine pituitary pars intermedia adenoma.

The objective of the study was to determine the sensitivity with which an adenoma of the pars intermedia of the pituitary gland can be predicted in horses by measuring the basal concentrations of glucose, cortisol, adrenocorticotropin (ACTH), and insulin, the urinary concentration of corticoids, the urinary corticoid:creatinine ratio, and the plasma cortisol concentration after the administration of 25 IU of ACTH intravenously. The records of 24 cases of histologically confirmed equine pituitary pars intermedia adenomas were used. An adenoma of the pars intermedia of the pituitary gland in horses was predicted with a sensitivity of 100, 100, and 92% for basal plasma ACTH (n = 16), the urinary corticoid:creatinine ratio (n = 7), and basal plasma insulin (n = 12), respectively. The sensitivity of the ACTH-stimulation test was 79% (n = 14).

Adenoma↗

PubMed1995

Liver triacylglycerol concentrations around parturition in goats with either pre-partum restricted or free access to feed.

The hypothesis was tested that goats allowed ad libitum access to feed during the dry period develop higher post partum hepatic triacylglycerol concentrations than do goats given a restricted amount of feed during the dry period. Goats in their second or more pregnancies were either given a restricted amount of hay, maize silage and concentrate (n = 5) or had free access to this feed mixture while the composition was kept constant (n = 11). After parturition both groups were allowed ad libitum access to feed. Post partum liver triacylglycerol concentrations, as measured in liver biopsies, were significantly raised in goats allowed ad libitum access to feed during the dry period. The increase in liver triacylglycerols was associated with slightly higher plasma concentrations of non-esterified fatty acids but lower serum 3-hydroxybutyrate concentrations. The feeding regimen during the dry period did not significantly influence post partum liver glycogen concentrations and serum levels of glucose, cholesterol, and insulin. The increase in post partum liver triacylglycerol concentrations in the goats allowed ad libitum access to feed instead of a restricted ration during the dry period, was associated with a significant rise in serum alkaline phosphatase activities, whereas other liver function and cell damage indicators in serum, i.e. aspartate aminotransferase, lactate dehydrogenase, gamma glutamyl transpeptidase, and bilirubin, were unchanged. Feed intake after parturition tended to be higher in the goats allowed ad libitum access to feed during the dry period but milk production was significantly raised.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗