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Biomedical subjects

M Chu

Publications and source records attributed to M Chu.

At least 73 records · Page 4Linked to original sources
PubMed1993

Colonic mucosal proliferation after pancreaticobiliary diversion in the hamster.

The effect of pancreaticobiliary diversion (PBD) on the colonic mucosa was studied in hamsters over 5, 10, and 24 days. Sham-operated animals served as controls. At all three time intervals, experimental animals had increased plasma cholecystokinin concentrations and decreased gastrin concentrations. Five days after PBD, there was an increase in scintigraphically measured [3H]thymidine incorporation into colonic tissue. Correspondingly, there was an increase in the [3H]thymidine DNA labeling index of goblet cells in the colonic mucosa. The total number of cells in the colonic crypt columns were significantly increased on days 5, 10 and 24. Whether this proliferative response in the colon is due to increased release of cholecystokinin, enteroglucagon, other aberrations of hormones or growth factors, or simply an increased bile load on the colonic mucosa remains to be clarified. Such further studies may reveal an alternative animal model for studies on risk factors in colonic carcinogenesis.

Animals↗
PubMed1993

Effects of pancreaticobiliary diversion and gastric fundectomy on azaserine-induced pancreatic carcinogenesis in the rat.

The effects of pancreaticobiliary diversion (PBD) and gastric fundectomy on the pancreas in azaserine-treated rats were studied over 14 months. Sham-operated azaserine-treated animals served as controls. A significant increase in pancreatic weight and total DNA and protein content was found in PBD-operated and fundectomized animals. DNA flow cytometry showed a significantly increased ratio of tetraploid to diploid cells in pancreatic tissue in both experimental groups. Mean values of all these variables were significantly higher after PBD than after fundectomy. Acidophilic atypical acinar cell foci of the pancreas were observed in all of the experimental and 75% of the control animals. The volume density of these foci was significantly higher in each experimental group than in the controls. The volume density, radioactive thymidine labeling index, and mitotic index of the foci were significantly higher after PBD than after fundectomy. Changes consistent with pancreatic adenoma were diagnosed in the PBD group only. It is concluded that not only PBD with endogenous hypercholecystokininemia, but also fundectomy with endogenous hypergastrinemia lasting about half of the life span in rats, induces pancreatic hypertrophy and enhances the development of precancerous pancreatic changes after azaserine treatment. In comparison with PBD, fundectomy caused less pronounced changes and no observable neoplasia.

Animals↗
PubMed1993

Pancreatic hypertrophy with acinar cell nodules after longterm fundectomy in the rat.

The effect of gastric fundectomy with hypergastrinaemia on the pancreas in rats was studied for 14 months. Rats with hypercholecystokininaemia that had had a pancreaticobiliary diversion (PBD) operation and sham operated rats served as controls. Fundectomised rats showed a significant increase in pancreatic weight and total DNA and protein content compared with sham operated rats. DNA flow cytometry showed a significantly higher ratio of tetraploid to diploid nuclei in pancreatic tissue after fundectomy than after sham operation. Mean values of all these variables were significantly lower after fundectomy than after PBD. Acidophilic atypical acinar cell foci of the pancreas were diagnosed in both fundectomised and PBD operated rats, but not in sham operated controls. The volume density and 3H-thymidine labelling index of the acidophilic atypical acinar cell foci were significantly lower after fundectomy than after PBD. Changes consistent with pancreatic adenoma were diagnosed in the PBD group only. In conclusion, fundectomy lasting about half of the life span in rats causes pancreatic hyperplasia and hypertrophy, as well as development of acidophilic atypical acinar cell foci. Although hypergastrinaemia is a prominent feature, it may not be the only factor responsible for this pancreaticotrophical effect of fundectomy.

Animals↗
PubMed1993

A novel class of platelet activating factor antagonists from Phoma sp.

Four novel platelet activating factor (PAF) antagonists, Sch 47918, Sch 49026, Sch 49027 and Sch 49028, were isolated from the fermentation broth of the fungal culture, Phoma sp. (ATCC 74077). The structures of these compounds were elucidated by spectroscopic methods. The structure and stereochemistry of the first isolated component, Sch 47918, were confirmed by single crystal X-ray diffraction analysis. Sch 49028, the most active component, was found to inhibit PAF-induced human platelet aggregation in vitro with an IC50 of 1.26 microM. However, this compound was inactive in vivo at 5 mg/kg, iv against PAF-induced bronchospasm in guinea pigs.

Animals↗
PubMed1993

[Social and health profile of the elderly population in Lima and Cuzco].

"Using a social focus approach, [this] research analyses the situation of health and self determination related to the environment of the aging population in Lima and Cusco [Peru], considering their ecological differences. One of the main results of the study is that of a high percentage of aged people without relatives living alone mainly in [institutions]. With regard to the health situation, almost one third of the interviewed in Lima declared [themselves] to be in good condition. However, in the highlands only 17% of the aging population achieves that condition." (SUMMARY IN ENG)

Adult↗
PubMed1993

Tidal volume peritoneal dialysis versus intermittent peritoneal dialysis.

In a 12-week crossover study we assessed the effect of tidal volume peritoneal dialysis (TVPD) on serum chemistry, patient well-being, appetite and sleep, blood pressure, and body weight period and compared it with the effect of intermittent peritoneal dialysis (IPD) on these same parameters over a similar period. We used similar volumes of dialysis solutions per exchange and session, and the exchanges were of the same duration in each session. There were 12 patients (6 males, 6 females) with a mean age of 76 years (range 61-88 years), and mean duration of peritoneal dialysis 49 months (range 20-148 months). Five patients started with TVPD and switched to IPD after 3 months; the remaining 7 patients started with IPD and switched to TVPD for the next 3 months. No differences were seen between TVPD and IPD in any of the measured parameters: body weight, appetite, sleep, and well-being by self-assessment, number of transfusions, and complications related to peritoneal dialysis. There were two episodes of peritonitis during the TVPD period and none during the IPD period. Our data indicate that TVPD and IPD are equally effective when applied over similar durations and with similar volumes of dialysis solutions in each session. The improved results with TVPD that others have reported probably can be explained by the use of higher volumes of dialysate.

Aged↗
PubMed1993

Pruritus in continuous ambulatory peritoneal dialysis and hemodialysis patients.

To study the prevalence and pathogenesis of uremic pruritus, CAPD and HD patients were asked to complete a questionnaire. The replies were quantitated based on numerical scales, and the results were compared with various hematological and biochemical parameters, underlying disease, and duration of dialysis. There were 113 CAPD patients (63 males and 50 females), mean age 60 (range 20-84) years, average time on CAPD 20 (range 1-163) months and 76 HD patients (44 males and 32 females) mean age 57 (range 23-81) years, mean time on HD 44 (range 2-242) months. Replies to questions were evaluated and graded by the same investigator who did not know the patients. Pruritus was present in 70 (62%) CAPD patients (64% in females and 60% in males p = NS) and in 41 (54%) HD patients (69% in females and 43% in males, p = 0.025). Before starting dialysis pruritus was present in 30% CAPD patients and 28% HD patients. Pruritus was graded as mild, moderate and severe; the distribution was 58.6%, 34.3%, and 7.1% (CAPD) and 43.9%, 41.5%, and 14.6% (HD), respectively. Dry skin was reported by 73% CAPD patients and 72% HD patients. This xeroderma was correlated with the severity of pruritus and was also present in 65% CAPD and 48.5% HD patients without pruritus. Patients with pruritus were older than those without pruritus both for CAPD (63 vs 54 years, p = 0.004) and HD (61 vs 51 years, p = 0.003). A significant correlation was observed only between pruritus score and age for CAPD patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Effects of gastric fundectomy and antrectomy on the exocrine pancreas in the hamster.

The effect of gastric fundectomy and antrectomy on growth of the exocrine pancreas was studied in hamsters over 5 and 25 d. Sham-operated animals served as controls. After 5 d, basal plasma gastrin concentrations were significantly increased in fundectomized animals (80.3 +/- 20.6 pmol/L) and significantly decreased in antrectomized animals (11.6 +/- 1.1 pmol/L) as compared with the controls (20.0 +/- 1.7 pmol/L). Similar differences were present among the 25-d groups, whereas basal plasma cholecystokinin (CCK) concentrations did not differ significantly between any groups at any time. At 5 d after fundectomy, there was a significant increase in pancreatic tissue [3H]-thymidine uptake and total DNA content, both of which were reduced 5 d after antrectomy. Autoradiography showed significantly increased [3H]-thymidine labeling index of acinar, intralobular duct, and centroacinar cells of the pancreas at 5 d after fundectomy. The increased intralobular duct cell labeling index persisted 25 d after fundectomy. Labeling indexes after antrectomy did not differ significantly from those in the controls, although antrectomized animals had the lowest values in all three cell compartments at 25 d. At 25 d, pancreatic wet wt and total DNA and protein content were significantly increased after fundectomy and significantly reduced after antrectomy. These findings indicate that fundectomy in the hamster induces pancreatic exocrine tissue hyperplasia and hypertrophy, whereas antrectomy leads to retardation of pancreatic growth.

Animals↗
PubMed1992

Endogenous hypercholecystokininemia model in the hamster: trophic effect on the exocrine pancreas.

Using Syrian golden hamsters, we studied the effect of pancreaticobiliary diversion (PBD) on plasma cholecystokinin (CCK) and exocrine pancreatic tissue over 5, 10, and 24 days. As compared with sham-operated controls, PBD-operated animals had increased plasma CCK concentrations by 228, 318, and 207% at 5, 10, and 24 days, respectively. Correspondingly, pancreatic wet weight increased by 24, 61, and 87%; total pancreatic protein by 6, 57, and 73%; and total pancreatic DNA by 35, 52, and 98%, respectively. At 5 days, but not at 10 and 24 days, there was a significant increase in the pancreatic tissue DNA concentration (p less than 0.01) and [3]H-thymidine incorporation into DNA (p less than 0.02). Autoradiography showed increased [3]H-thymidine labeling index in acinar cells at 5 and 10 days after PBD (p less than 0.01 and p less than 0.005). Although not significant, ductal cell labeling index was also increased at 5 and 10 days. These findings provide evidence that, as in the rat, PBD in the hamster induces hypercholecystokininemia with ensuing pancreatic hyperplasia and hypertrophy. The hamster model may be useful for studies on the effect of endogenous CCK on pancreatic ductal cell carcinogenesis and diseases of the gallbladder, neither of which can be studied in the rat.

Animals↗
PubMed1992

Gastric fundic epithelial proliferation after pancreaticobiliary diversion. Studies with quantitative histological analysis and autoradiography in the hamster.

The effect of pancreaticobiliary diversion (PBD) with hypercholecystokininemia on the gastric fundic mucosa was studied in the Syrian golden hamster over 5 and 24 days. Sham-operated animals served as controls. Basal plasma gastrin concentrations were significantly decreased on days 5 and 24. Five days after PBD, there was a significant increase in the scintigraphically measured [3H]-thymidine incorporation into fundic tissue. Correspondingly, there was a significant increase in the number of cells with [3H]-thymidine-labeled DNA in the proliferative zone of the fundic mucosa. The total number of cells in the gastric pits, the number of cells in the proliferative zone and the proliferation index were also significantly increased 5 days after PBD. Although the mean values of all variables were higher after PBD than in the control group on day 24, these increases were not significant. It is concluded that PBD at least transiently stimulates gastric fundic epithelial proliferation in the hamster. Whether this is an effect of hypercholecystokininemia remains to be definitely proven in further studies.

Animals↗
PubMed1992

Effects of gastric fundectomy and antrectomy on the colonic mucosa in the hamster.

The effects of gastric fundectomy and antrectomy on the colonic mucosa were studied in hamsters over 5 and 25 days. Sham-operated animals served as controls. Basal plasma gastrin concentrations were significantly increased after fundectomy and significantly decreased after antrectomy. Five days after fundectomy, there was a significant increase in scintigraphically determined colonic tissue [3H]-thymidine uptake and [3H]-thymidine labeling index of goblet cells, both of which were reduced 5 days after antrectomy. After fundectomy, the labeling index was maximal in differentiating-proliferative cells in the midportion of the colonic crypts, whereas the labeling index of the immature proliferative cells at the base of the crypts did not differ from that in the controls. On day 25, the crypt size and the number and percentage of goblet cells in the crypts were significantly increased in fundectomized animals. The number and percentage of goblet cells in antrectomized animals were significantly reduced on day 25. It is concluded that fundectomy in the hamster induces colonic mucosal hyperplasia with goblet cell proliferation, whereas antrectomy leads to retardation of colonic goblet cell proliferation.

Achlorhydria↗
PubMed1992

Effect of pancreaticobiliary diversion on liver regeneration.

To ascertain whether the increase in cholecystokinin (CCK) level associated with pancreaticobiliary diversion has a cytoproliferative effect on the liver similar to that on the pancreas, we studied three groups of rats: group I (n = 19) had a pancreaticobiliary diversion and 4 weeks later a 70% liver resection, group II (n = 13) had a liver resection only, and group III (n = 6) underwent a sham liver operation. Tissue samples were taken from the liver and pancreas 48 h after the liver operation. Liver regeneration was evaluated on the basis of continuous incorporation of tritiated thymidine into hepatocytes, liver weight, and DNA content. For confirmation of the increase in CCK levels the effects on the pancreas was studied by measuring wet weight, total protein, and total DNA content. The results showed trophic effects on the pancreas, as expected, but no effects whatsoever on liver regeneration. CCK does not seem to have any role in the regulation of liver regeneration.

Animals↗
PubMed1991

Proliferative response of different exocrine pancreatic cells after surgical pancreaticobiliary diversion in the rat.

Pancreaticobiliary diversion (PBD) is known to induce chronic, endogenous hypercholecystokininemia causing pancreatic growth in rats. In the present study the proliferative response of the different exocrine pancreatic cells was studied by administration of 3H-thymidine, 1 mCi/kg, given 1 h before the rats were killed and 5, 10, 20, and 40 days after PBD. DNA and 3H-thymidine uptake, both expressed per 1 mg of pancreatic tissue, were significantly increased on day 5. The nuclear labeling index was increased fivefold in both the acinar and ductal cell group. In the centroacinar cell group the labeling index was increased on day 10. In conclusion, we found that the proliferative activity after PBD occurred during the first 10 days and that the ductal cells were forced into proliferation to the same extent as the acinar ones. These findings are of interest for future studies of hormonal influences on the development of pancreatic carcinoma.

Animals↗
PubMed1990

A splint for controlled active motion after flexor tendon repair. Design, mechanical testing, and preliminary clinical results.

A splint for controlled active motion after flexor tendon repair is described. It incorporates a single core-coated elastic band passing around a palmar pulley and attached proximally to a spring wire. Its mechanical properties were tested against six other systems. The tension in various systems all rose near full extension. However, the palmar pulley, the spring wire, and the elastic band each could lower the tension significantly. When the bending moments at the interphalangeal joints were measured, all systems produced a peak during the latter part of extension. With the palmar pulley, spring wire, and elastic band, the rise was minimal and in fact, the bending moments diminished near full extension. Initial results in 28 flexor tendon repairs using this splint showed less flexion contracture when compared with 78 flexor tendon repairs using a standard rubber band anchored at the wrist.

Biomechanical Phenomena↗