PubMed Health⌕ Search

Biomedical subjects

T Hendriks

Publications and source records attributed to T Hendriks.

123 records · Page 7Linked to original sources
PubMed1984

Bile acid drainage by partial small bowel bypass or cholestyramine. Effects on serum cholesterol in Watanabe heritable hyperlipidemic rabbits.

The effects of bile acid drainage on serum cholesterol levels have been investigated in Watanabe heritable hyperlipidemic rabbits, a unique model for homozygous familial hypercholesterolemia. Cholestyramine medication lowered serum cholesterol concentrations with 38%, while a 33% and a 50% small bowel bypass resulted in a decrease of 56 and 48%, respectively. Cholestyramine treatment after either bypass induced a minor additional fall in serum cholesterol. Ileal bypass and ileal resection were equally effective in reducing serum cholesterol. These results indicate the necessity for further investigation into the potential of bile acid drainage as a therapy in homozygous familial hypercholesterolemia.

Animals↗
PubMed1984

A reproducible model for protracted peritonitis in the rabbit.

The intra-abdominal implantation of a gelatin capsule containing human fecal material introduces peritonitis in the rabbit. The severity of the disease and the length of survival depend on the volume of the inoculum. A 7-day survival chance varies between 45 and 92%, depending on fecal loading. All rabbits develop intra-abdominal abscesses and in the surviving animals infection persists for at least a week, allowing further study of several aspects of peritonitis.

Abscess↗
PubMed1984

The glucagonoma syndrome: stimulus-induced plasma responses of circulating glucagon components IRG9000 and IRG3500.

Plasma responses of the major immunoreactive glucagon (IRG) components have been investigated in a case of glucagonoma syndrome. Fasting plasma IRG was 4155 pg/ml. Gel chromatography of plasma revealed that 66% of immunoreactivity was present as IRG9000, while IRG3500 accounted for an additional 26%. The appearance in peripheral plasma of these two glucagon fractions was examined after administration of a number of compounds. IRG levels were clearly elevated after arginine and tolbutamide. Both calcium and calcitonin induced a biphasic rise of IRG, the increase being slower after calcium administration. Somatostatin suppressed plasma IRG levels. All tests induced changes in both IRG3500 and IRG9000. In general, relative changes were more pronounced in IRG3500 than in IRG9000, while absolute changes were greater in IRG9000. The shape of the response curves of IRG3500 and IRG9000 was quite similar after arginine, calcium and somatostatin. After tolbutamide the IRG9000 response was delayed as compared to the IRG3500 component. During the latter part of the calcitonin infusion, IRG9000 remained elevated while IRG3500 was back at its starting level.

Adenoma, Islet Cell↗
PubMed1983

Partial ileal bypass inhibits atherosclerosis in WHHL rabbits.

The effectiveness of partial ileal bypass (PIB) as a counter-measure against atherosclerosis was evaluated in WHHL rabbits. The effects of PIB and sham operation, each performed in five animals, on serum lipids, lipoproteins and plaque formation were investigated. PIB resulted in an immediate and sustained decrease of 52% (range 29-67%) in serum cholesterol, while sham operation had no effect. The main reduction was in LDL cholesterol; VLDL-cholesterol was lowered to a lesser extent. PIB also appeared to change the electrophoretic behaviour of total serum, very low density and low density lipoproteins. Plaque formation, measured 30 weeks after operation in various aortic segments and arteries, was significantly reduced after PIB. It is concluded that an induced lowering of serum cholesterol can prevent atherosclerosis in WHHL rabbits. Also, these animals must be considered as a model for the receptor-defective cellular phenotype of homozygous familial hypercholesterolemia, not for the receptor-negative type, which is the only truly genetically homozygous form.

Animals↗
PubMed1981

On the stability of immunoreactive glucagon in plasma samples.

The stability of glucagon immunoreactivity in plasma samples, as measured with antiserum 30K, has been investigated. Post-prandial blood samples were collected and processed both with added Trasylol at 4 degrees C and without Trasylol at room temperature. Incubation at room temperature for up to 7h without added Trasylol did not result in significant loss of 30K-immunoreactive glucagon. Blood samples both from non-diabetic and diabetic persons could be collected and centrifuged at room temperature and stored at -20 degrees C without Trasylol for more than 2 months without loss of 30K-immunoreactivity, as compared to Trasylol-containing controls kept at 4 degrees C during handling. The distribution of 30K-immunoreactive glucagon over the various components, obtained after chromatography of plasma on Ultrogel AcA54, was not significantly altered when blood samples, both from normal persons and from patients with chronic renal failure, were processed at room temperature and subsequently stored at -20 degrees C without addition of Trasylol. Our results indicate that collection and centrifugation of blood at room temperature without the addition of a proteinase inhibitor and subsequent storage at -20 degrees C does not result in loss of 30K-immunoreactive glucagon.

Blood Preservation↗
PubMed1975

Movement of calcium through artificial lipid membranes and the effects of ionophores.

The calcium efflux from multi-layered vesicles (liposomes) of different lipid composition has been studied. Liposomes composed of lipids extracted from cattle retinas are compared with liposomes which consist of phosphatidylcholine or a 1:1 phosphatidylcholine/phosphatidylserine mixture. The percentages of 45-Ca capture by these three types of liposomes are 10, 1 and 4% respectively; The efflux rates are 2.5-10- minus 6, 2-10- minus 6 and 4-10- minus 5 S- minus 1 respectively. The semilogarithmic efflux curves for phosphatidylcholine and phosphatidylcholine/phosphatidylserine liposomes are linear with time, but those for the retinal lipid liposomes are discontinuous. The activation energy for the calcium efflux from the latter liposomes is about 10.5 kcal/mol, both before and after the discontinuity. The ionophores X537A and A23187 enhance the calcium leakage from retinal lipid liposomes, the latter ionophore being much more effective than the former. At high concentrations both ionophores seem to transport calcium as a 1: 2 Ca-ionophore complex. At low ionophore concentrations, however, X537A appears to transport calcium as a 1:1 complex, but A23187 as a 2:1 complex.

Animals↗
PubMed1970

Hormonal interactions in Mucor mucedo and Blakeslea trispora.

Evidence is presented that progametangia in both the plus and the minus mating types of Mucor mucedo can be induced by one substance, namely (-)-trisporic acid B. A method is described for the determination of the concentration of the sex factors (trisporone, trisporic acid B, trisporic acid C) in mated cultures of Mucorales by polarography. It can be demonstrated that the amount of plus mycelium is limiting for the production of the sex factors in Blakeslea trispora. It is shown that the minus type of this organism is able to synthesize the sex factors when incubated in the filtered medium of a mated culture. Cycloheximide and 5-fluorouracil inhibit strongly the sex factor production in a mated culture of B. trispora at any time. This result suggests that sexual activity comprises the synthesis of proteins which are involved in the production of the sex factors.

Acids↗
PubMedDate not supplied

Characterization of the non-specific lipid transfer protein EP2 from carrot (Daucus carota L.).

The extracellular protein EP2 was previously identified as non-specific lipid transfer protein based on its cDNA-derived amino acid sequence. Here, the purification of the EP2 protein from the medium of somatic embryo cultures is described. After two cycles of ion-exchange and gel permeation chromatography, a single silver-stained protein band with an apparent molecular mass of 10 kDa was observed on SDS-PAGE. This protein band was recognized by the antiserum raised against a EP2-beta-galactosidase fusion-protein. Employing a fluorescent phospholipid analog, it was shown that the purified EP2 protein is capable of binding phospholipids and is able to enhance their transfer between artificial membranes. Employing a gel permeation assay, it could be demonstrated that the EP2 protein is also capable of binding palmitic and oleic acid as well as oleyl-CoA. Because in plants these fatty acids are used as precursor molecules for cutin, these results are in support of the proposed role of the EP2 protein to transport cutin monomers from their site of synthesis through the cell wall of epidermal cells to sites of cutin polymerization.

Carrier Proteins↗
PubMedDate not supplied

Pancreatic islet transplantation prevents the impaired healing of intestinal anastomoses in Lewis rats with streptozotocin-induced diabetes.

Pancreatic islet transplantation may prevent secondary complications of diabetes mellitus, but its potential benefits on early complications have been incompletely examined. The objective of this study was to investigate whether preoperative islet transplantation would normalize impaired healing of intestinal anastomoses in diabetic rats. Male Lewis rats were divided into a control group (I), an uncontrolled diabetic group (II), and a transplant group (III). Nine days before surgery, groups II and III were rendered diabetic by injection of streptozotocin. Two days before surgery, group III received an intrahepatic isogenic two-donor islet graft, whereas groups I and II underwent sham transplantation. On day 0, all animals underwent resection and anastomosis of both ileum and colon. Half of the animals in each group were killed on day 3 and the other half were killed on day 7. Blood glucose levels in group II rats remained over 20 mmol/L throughout the experiment, whereas in group III rats they were normalized within 24 hours after transplantation. At death, group II rats, but not groups I and III rats, showed a high incidence of anastomotic abscesses. Uncontrolled diabetes lowered anastomotic strength, and transplantation prevented this reduction. For instance, anastomotic bursting pressure in the ileum on day 3 was 11.9 +/- 4.8 kPa in group I rats, 3.3 +/- 3.0 kPa in group II rats, and 11.1 +/- 4.3 kPa in group III rats. Rupture on day 3 always occurred within the anastomosis, whereas on day 7 intra-anastomotic ruptures were only observed in group II rats. No differences between the groups were found for either anastomotic hydroxyproline concentration or content. However, the acid solubility of anastomotic collagen was significantly higher in group II rats than in groups I and III rats. Thus, uncontrolled diabetes lowers anastomotic strength without affecting anastomotic collagen content. Defective repair is prevented by pancreatic islet transplantation before surgery.

Journal Article↗