PubMed Health⌕ Search

Biomedical subjects

T Hendriks

Publications and source records attributed to T Hendriks.

At least 109 records · Page 6Linked to original sources
PubMed1988

On the fluorometric assay of circulating lipoperoxides.

The methodology for the measurement of circulating thiobarbituric acid (TBA)-reactive products of lipid peroxidation in human plasma by means of fluorometry has been reinvestigated. The lipid precipitation of plasma with phosphotungstic acid, which step is laid down in the standard assay method, strongly increases the apparent TBA-reactivity. However, subsequent washing of the precipitate may reduce the apparent levels of lipoperoxide to values close to those obtained by using untreated plasma. Also, short-time storage of plasma at either 4 degrees C or -20 degrees C induces large day to day variations in assay results. This phenomenon may be prevented almost completely by the addition of glutathione plus EDTA. It is proposed to use untreated plasma and to perform the assay immediately after collection of plasma or to add both glutathione and EDTA before storage.

Edetic Acid↗
PubMed1988

Enterostomy as an adjunct to treatment of intra-abdominal sepsis.

In 60 patients a small bowel enterostomy was constructed as part of the treatment of various intra-abdominal infectious and obstructive conditions. Eleven patients (18 per cent) died in the immediate postoperative period from continuing sepsis. In one patient closure of the stoma was not considered because of disseminated malignancy. In the remaining 48 patients continuity of the gut was subsequently restored. In 22 patients (46 per cent) complications occurred, 12 (25 per cent) of which were intra-abdominal septic complications. The occurrence of intra-abdominal complications was found to be linked to premature (i.e. within 3 months) closure of the stoma. Reasons for premature closure were stomal difficulties and prerenal azotaemia. Stomal closure was attended by a 10 per cent mortality rate.

Abscess↗
PubMed1988

Collagen in colorectal cancer in relation to clinicopathologic stage and histologic grade.

Interstitial collagen is a major constituent of the tumor matrix. The quantity of this protein may influence the prognosis. The collagen content of 54 colorectal tumors, measured as the hydroxyproline concentration in relation to clinicopathologic stage and histologic grade, was investigated and no support for either a negative or positive influence on the prognosis.

Adenocarcinoma↗
PubMed1987

Effects of partial ileal bypass on the progression of atherosclerotic lesions in WHHL rabbits.

At age of 40 weeks, 9 WHHL rabbits were necropsied as a baseline control group for evaluating aortic and coronary atherosclerosis. An additional 18 WHHL rabbits of the same age underwent either a partial ileal bypass (PIB) or a sham operation. Serum cholesterol concentrations were significantly lower in PIB rabbits than in sham-operated rabbits, mean postsurgical values being 7.9 +/- 2.3 mmol/l and 13.2 +/- 2.4 mmol/l, respectively. This effect was mainly due to a lower LDL-cholesterol concentration. Serum triglycerides remained unaffected. Thirty weeks after surgery the PIB and sham rabbits were necropsied and atherosclerosis was evaluated. Progression of atherosclerotic plaque size in the sham group was most prominent in the aortic arch. PIB largely prevented this progression. The frequency of plaque complications in the aortic arch also increased in the sham groups. Here, no significant improvement was found in the PIB group. Extensive examination of the heart showed some affected coronary arteries in every 40-week-old WHHL rabbit. Progression of coronary atherosclerosis during the postsurgical period was small in both sham and PIB groups. However, while PIB did not affect the plaque size, it significantly reduced the number of coronary arteries affected.

Animals↗
PubMed1987

Healing of experimental colonic anastomoses: effect of antineoplastic agents.

The effect of a combination of antineoplastic agents (bleomycin (2 mg/kg/d), 5-fluorouracil (10 mg/kg/d) and cisdiamminedichloroplatinum (0.35 mg/kg/d)), given intravenously, on the healing of colonic anastomoses was investigated in rats. Ninety-six male Wistar rats were divided into four groups. A control group of rats underwent surgery only. The remaining rats were operated either 2 days before, 2 days after or during the 5-day chemotherapy course. In all groups rats were killed after 3, 7 and 21 days. Wound healing of the anastomosis was assessed by measuring the bursting pressures and hydroxyproline contents. Operating in the middle of the 5-day chemotherapy course had the greatest effect on anastomotic healing. This was most apparent on the seventh day postoperatively. When surgery was performed on the second day after the chemotherapy course there was an early delay in wound healing as measured by hydroxyproline content. Seven days postoperatively concentrations were in the same range as those in the control group. Chemotherapy commencing 2 days after surgery did not affect anastomotic healing as compared to the control group. Bursting pressure and hydroxyproline content at the end of the experiment were more or less comparable in all groups.

Animals↗
PubMed1986

Transport and processing of endocytosed lysosomal alpha-glucosidase in cultured human skin fibroblasts.

In the present study we have characterised the molecular products that arise from processing of a precursor form of alpha-glucosidase isolated from urine after endocytosis at 37 degrees C by cultured human skin fibroblasts. The urinary precursor (Mr 110 000) was processed to forms with Mr of 100 000, 80 000 and 74 000. These forms were approximately 4000 Da larger than the corresponding forms of endogenously synthesized alpha-glucosidase. Digestion of the different forms of the enzyme with endoglycosidase F showed that the differences in apparent molecular mass between the exogenous and corresponding endogenous forms were due to difference in glycosylation. Intracellular transport of endocytosed alpha-glucosidase was followed by incubating fibroblast homogenates with glycyl-L-phenylalanine-beta-naphthylamide (Gly-Phe-NH-Nap), which leads to specific lysis of lysosomes. Transport to the lysosomes was a fast process: within 45 min after endocytosis more than 50% of the enzyme was present in the lysosome. The first step in the processing of endocytosed alpha-glucosidase started in a Gly-Phe-NH-Nap-insensitive (prelysosomal) compartment, but further processing of the enzyme to lower-Mr forms was coupled to transport to the lysosomes. Processing of alpha-glucosidase after uptake at 20 degrees C was also studied. At this temperature the enzyme accumulated in an organelle with a low buoyant density, presumably the endosome; this compartment appeared to be heterogeneous, ranging in density from 1.04 g/ml to 1.08 g/ml. Under these conditions only the first step in the processing of the enzyme occurred. It is concluded that endocytosed enzyme is processed more rapidly than endogenously synthesized enzyme owing to the fact that endocytosed enzyme is transported more rapidly to the lysosomes. Furthermore, processing may start in a prelysosomal organelle.

Biological Transport↗
PubMed1986

The effect of antineoplastic agents on the healing of small intestinal anastomoses in the rat.

The influence of an intravenous 5-day combined chemotherapy with bleomycin (2 mg/kg/d), 5-fluorouracil (10 mg/kg/d) and cis-diamminedichloroplatinum (0.35 mg/kg/d) on the healing of ileal anastomoses was investigated in rats. Ninety-six male Wistar rats were used, divided into four groups. The rats in the control group had surgery without administration of cytostatic agents. The other rats were operated either 2 days after, 2 days before, or during the 5-day chemotherapy course. In each group, rats were killed after 3, 7, and 21 days. Anastomotic healing was assessed by measurement of bursting pressures and hydroxyproline levels. Intestinal healing appeared to be impaired most if the operation was performed in the middle of the antineoplastic chemotherapy course. The effects were most pronounced on the seventh postoperative day. Surgery on the second day after the chemotherapy course led to a slight and early delay in wound healing as measured by the hydroxyproline content. Seven days postoperatively, concentrations had returned to preoperative values. Surgery 2 days before chemotherapy induced only minor differences with respect to the control group. In all groups, bursting pressure and hydroxyproline content at 21 days were similar. Thus, antineoplastic agents retard but do not prevent healing of intestinal anastomoses. The effects are most pronounced when surgery is performed during chemotherapy. If possible, surgery should be performed prior to chemotherapy. Increasing the time interval between surgery and chemotherapy may decrease the delay in intestinal woundhealing.

Animals↗
PubMed1986

A spectrophotometric microassay for sulfated glycosaminoglycans using a laser densitometer.

The absorption spectrum of the dye 1,9-dimethylmethylene blue shifts if complexed with sulfated glycosaminoglycans. The present method uses the decrease in A633 rather than the increase in A535, described in a recent method, to measure the sulfated glycosaminoglycan content of biological samples. A conventional spectrophotometer was used to estimate the levels of sulfated glycosaminoglycan in papain extracts from intestinal wall tissue, by measuring both the A535 and the A633 and comparing them with a chondroitin sulfate standard: a highly significant correlation (r = 0.974, n = 17) was obtained. Also, interference by substances like RNA, DNA, and hyaluronic acid was similar for both methods. These results allowed us to employ a laser densitometer with a helium/neon laser emitting at 633 nm to improve the sensitivity and the capacity of the assay. The combination of a small reaction volume and a high-intensity light source allows the detection of less than 0.1 microgram chondroitin sulfate, a 40-fold improvement in sensitivity as compared with the original method. A very significant correlation (r = 0.885, n = 17) existed between results obtained with the macroassay, using a spectrophotometer, and those found by employing the microassay, using the laser densitometer. The use of microtiter plates and the screening potential of the densitometer yields an assay which is fast, very sensitive, and suitable for processing large numbers of samples.

Animals↗
PubMed1986

Anastomotic insufficiency in small bowel surgery--incidence and treatment.

In the period 1977-1981 234 small bowel anastomoses were constructed in 143 patients. Eight anastomoses showed leakage (3.4%) and from nine anastomoses a fistula developed (3.8%): a total rate of disturbed healing of small bowel anastomoses (7.3%). In the presence of intra-abdominal infection this rate was 14.8%, in the absence of infection 0.8%. The results of treatment with oversewing and with resection and immediate anastomosis were disappointing. Better results were obtained by dismantling of the anastomosis, establishment of a split-enterostomy and reestablishment of continuity in a second stage. Mortality was 3/17 (18%). The literature is reviewed.

Adolescent↗
PubMed1985

Solubility of tissue hydroxyproline in experimental intestinal anastomoses.

Salt and acid solubility of collagen are thought to reflect its degree of crosslinking. In order to examine postoperative changes in crosslinking of intestinal collagen, which are of importance to the stability of the intestinal wall, we have investigated the solubility of hydroxyproline in rabbit ileum and colon, both in unwounded intestine and after construction of an anastomosis. Solubility in salt and dilute acid was increased by a sonication procedure. This way, 9% of total hydroxyproline in the unwounded colonic wall was salt soluble and 65% acid soluble. A similar distribution was observed in ileum. Three days after operation the salt-soluble fraction was significantly elevated in samples from the anastomotic area. In colon, this increase also persisted 7 days postoperatively. Comparison of anastomotic samples collected 3 and 7 days after surgery shows a significant decrease in the acid-soluble and a significant increase in the solid fraction. This phenomenon occurs both in ileum and colon. These results indicate that during the first days after operation the integrity of the intestinal wall is weakened not only by a loss of collagen, but also by a changed solubility of the remaining collagen.

Animals↗
PubMed1985

Loss of collagen from experimental intestinal anastomoses: early events.

Collagen lysis, which always occurs to some extent in the wound area, is thought to be the underlying cause for breakdown of intestinal anastomoses. Therefore, we have studied the loss of collagen around ileal and colonic anastomoses in New Zealand White rabbits during the first 48 hr after operation. In the ileum, significant lysis of collagen in the anastomotic area, as represented by a decreased level of hydroxyproline, occurs from 12 hr postoperatively onward. Maximal loss of hydroxyproline, as compared to preoperative values, is 27% measured 24 hr after operation. In the colon, significant lysis of collagen occurs after 3 hr. The lowest level of hydroxyproline measured during the experimental period is found 48 hr after operation, where the concentration is decreased by 38%. Changes in ileum are restricted to the anastomotic area, while in the colon the decrease in hydroxyproline extends along the intestinal wall, particularly in a proximal direction. The fact that total protein concentrations do not vary significantly indicates that the lowered hydroxyproline levels are specific. Microscopic examination of the wound area shows that the cellular response during the first 24 hr after wounding is restricted to granulocytes. It is suggested that granulocyte collagenase is mainly responsible for the observed lysis of collagen after intestinal anastomosis.

Animals↗
PubMed1985

Histological features of wound repair: a comparison between experimental ileal and colonic anastomoses.

Various histological parameters of wound repair have been studied in intestinal anastomoses in the rabbit in order to compare the healing processes in ileum and colon. The sequentional appearance of granulocytes, macrophages and fibroblasts has been studied from 3 h to 7 days after operation. Also, degree of necrosis, formation of capillaries and mucosal repair were analysed semi-quantitatively. Significant differences were observed between ileal and colonic anastomoses with respect to occurrence of granulocytes, necrosis and mucosal repair, particularly 7 days after operation. At that time, granulocytes and necrosis were virtually absent from ileal anastomoses, while mucosal integrity was restored in the majority of cases examined. In contrast, granulocytes and necrosis were still abundantly present in colonic anastomoses and mucosal repair was poor. These results support biochemical evidence that wounds in the ileum heal more rapidly than wounds in the colon. Possibly, the sustained presence of granulocytes, which are a potential source of collagenase activity, is important in this respect. Investigation of the same features of intestinal wound healing in rabbits with peritonitis induced by infection showed similar results and no differences were found between infected and non-infected animals.

Animals↗
PubMed1985

A comparative study on serum lipids and atherosclerotic plaque formation in diet-induced and familial hypercholesterolemia in rabbits, and the effect of partial ileal bypass.

Aim of the present study was to compare an alimentary and a hereditary rabbit model for hypercholesterolemia. Serum lipids, serum lipoproteins and distribution and prevention of atherosclerotic plaque formation were studied in (1%) cholesterol-fed NZW rabbits and both heterozygous and homozygous WHHL rabbits. Cholesterol-fed NZW rabbits showed a hypercholesterolemia without hypertriglyceridemia, caused by accumulation of a spectrum of cholesterol ester-rich beta-migrating lipoproteins with a relatively low density. The WHHL rabbits displayed both a hypercholesterolemia with an elevation of LDL, and a hypertriglyceridemia. The hypertriglyceridemia in the WHHL homozygotes was due to accumulation of VLDL remnants and in the heterozygotes to a slight rise in normal pre-beta VLDL. Despite the pronounced quantitative and qualitative differences in lipoproteins, the location and extent of atherosclerotic plaques which had developed after 13 weeks cholesterol-rich diet in NZW rabbits and in 10 months old homozygous WHHL rabbits, was quite similar. Partial ileal bypass surgery lowered serum cholesterol in all three groups and also prevented atherogenesis.

Animals↗
PubMed1984

Wound healing in the intestinal wall. A comparison between experimental ileal and colonic anastomoses.

The healing of ileal and colonic anastomoses is compared in rabbits. The intestinal segment that contains the anastomosis shows a temporary loss of strength, which is reflected in a decreased bursting pressure. This loss of strength is accompanied by a massive loss of collagen, measured as hydroxyproline, both in ileum and in colon. In ileum, hydroxyproline concentrations, expressed on a dry weight basis, are lowered by 30 per cent, one day after operation. Thereafter, they rise again, after seven days reaching a level that is 40 per cent enhanced as compared with unwounded tissue. Maximal decrease in colon, measured two days after operation, is 40 per cent. After seven days hydroxyproline levels are back at preoperative values. In colon, significant loss of hydroxyproline is also apparent in the intestinal segment proximal to the anastomosis. This phenomenon does not occur in ileum. These results clearly demonstrate that after ileal anastomosis a loss of collagen occurs similar to that in colonic anastomoses. The fact that the loss of collagen is less extensive and more rapidly restored may be important in explaining the lesser incidence of leakage encountered after surgery of the small intestine.

Animals↗
PubMed1984

Wound healing in the intestinal wall. Effects of infection on experimental ileal and colonic anastomoses.

The healing of both rabbit ileal and colonic infected anastomoses has been investigated. Infection was induced by implanting a capsule with human fecal material in the anastomotic area. Infection did result in lowered bursting pressures, which effect was most pronounced in ileum seven days postoperatively. In general, the average hydroxyproline levels in and around infected anastomoses were lower than the hydroxyproline concentrations measured around noninfected anastomoses. This difference was most significant in the segment proximal to the ileal anastomosis seven days after operation, in the segment distal to the colonic anastomosis three days after operation, and in the segment proximal to the colonic anastomosis seven days after operation. It is concluded that infection interferes with the early stages of the healing sequence in rabbit intestinal anastomoses, profoundly affecting collagen metabolism. Our work does not support recent publications that report an unchanged or even increased wound strength under infected conditions.

Animals↗
PubMed1984

Does nifedipine suppress atherogenesis in WHHL rabbits?

The effects of the calcium antagonist, nifedipine, on atherogenesis were investigated in WHHL rabbits, a unique animal model for human familial hypercholesterolemia. Nifedipine, in a daily dose of 40 mg, was fed orally to 9 rabbits over a period of 26 weeks, resulting in serum concentrations of between 740 and 1370 ng/ml. Rabbits were killed at an age of 40 weeks and atherosclerotic plaque formation in various aortic segments was quantified. Atherosclerosis was most pronounced in the aortic arch and the thoracic aorta, plaques covering, respectively, 59 +/- 17% and 17 +/- 9% of total vessel area. These results are similar to those observed in a control group, which received the same diet and no nifedipine and displayed lesions on 62 +/- 19% and 21 +/- 13% of total area of aortic arch and thoracic aorta, respectively. Although variations in plaque area between WHHL rabbits are large and thus preclude the observation of small effects, the efficacy of nifedipine as an anti-atherogenic agent in rabbits with hereditary hypercholesterolemia appears questionable.

Animals↗
PubMed1984

The lipid-lowering effects of 3-hydroxy-3-methylglutaric acid and bile acid drainage in WHHL rabbits.

The effect of 3-hydroxy-3-methylglutaric acid (HMG) on serum cholesterol levels was investigated in Watanabe heritable hyperlipidaemic (WHHL) rabbits. Oral administration of HMG resulted in a reduction of serum cholesterol by 39%. Bile acid drainage, by means of either cholestyramine medication or partial ileal bypass (PIB) surgery, also led to significant reductions in circulating cholesterol, by 35 and 59% respectively. Intraperitoneal injection of HMG after PIB surgery further reduced serum cholesterol by 35%. Fibroblasts from the WHHL rabbits did not show high-affinity binding, uptake or degradation of 125I-labelled low density lipoprotein (LDL). The working mechanism of these lipid-lowering lowering therapies in WHHL rabbits is discussed in relation to recent literature. The significant reductions in circulating cholesterol induced by HMG warrant further investigation into the use of this compound in the management of familial hypercholesterolaemia.

Animals↗