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Biomedical subjects

G S Yu

Publications and source records attributed to G S Yu.

At least 37 records · Page 2Linked to original sources
PubMed1991

In vitro model of attachment of Giardia intestinalis trophozoites to IEC-6 cells, an intestinal cell line.

Attachment of giardias to intestinal cells has been difficult to study because of a lack of a convenient in vitro model. We developed an assay for attachment of radiolabeled trophozoites to IEC-6 cells that can be done in microtiter trays. Attachment was confirmed by scanning and transmission electron microscopy. Trophozoites remained attached to the IEC-6 cells for 24 h with little evidence of damage to the IEC-6 cells. Preincubation of trophozoites with cytochalasins A, B, and D reduced attachment to approximately 20% of that of controls, whereas colchicine had no effect. Chelation of divalent cations with EDTA and EGTA [ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid] reduced attachment to 24 and 26% of control values, respectively, and incubation at 4 degrees C reduced attachment to 7% of the value for controls incubated at 37 degrees C. Glutaraldehyde fixation of trophozoites or IEC-6 cells resulted in significantly diminished attachment to the live substrate (17 and 40% of control values, respectively). Coincubation of IEC-6 cells and trophozoites on a rotary shaker resulted in detachment of 40% of trophozoites, but EDTA, EGTA, glutaraldehyde fixation of trophozoites, and low temperature diminished attachment markedly and significantly. Similar results were obtained in selected experiments with three strains of giardia.

Animals↗
PubMed1990

Dynamic changes of pancreatic structure and function in rats treated chronically with nicotine.

Adult, male Sprague-Dawley rats weighing initially 185-225 g, were treated with 5, 15, or 50 mg nicotine or placebo 3-week-release pellets by sc implantation, for 1.5, 3, 6 and 12 weeks. These doses of nicotine correspond to infusion rates of 9.9, 29.8, and 99.2 micrograms/h, respectively. At the highest nicotine dose trypsin and chymotrypsin activities were markedly higher in pancreas from 12-week nicotine-treated rats compared with controls. This was associated with a fourfold increase in steady-state amylase mRNA levels in comparison to placebo controls. In addition, secretagogue-stimulated enzyme release from pancreatic acini isolated from rats treated with 50 mg nicotine pellets was significantly higher than controls at 1.5 and 3 weeks and declined below control levels after 12 weeks of treatment. In rats treated with 15-mg nicotine pellets, maximal secretagogue-stimulated enzyme release from isolated acini occurred at 1.5 weeks, declining thereafter to control levels. Electron microscopy of pancreas from rats treated with the 50 mg nicotine dose revealed intracytoplasmic vaculoes appearing after 3 weeks of treatment, and persisting throughout the remaining experimental period. It is concluded that 12-week nicotine treatment results in increased pancreatic enzyme biosynthesis and accumulation of digestive enzymes within the pancreas. This is associated with altered responsiveness to secretagogues and evidence of morphological damage.

Amylases↗
PubMed1990

IgA nephropathy in alcohol abuse. An animal model.

In search of an animal model for alcohol abuse related IgA nephropathy, we investigated the Tsukamoto-French alcoholic rat. Continuous intoxication was induced by gastric infusion of a liquid diet with up to 47% ethanol in Wistar rats designated "alcoholic". Control animals received the same calorie count in the form of glucose. Animals were sacrificed after 6 or 10 weeks. IgA nephropathy was observed in 67% (10 of 15) of alcoholic rats and in none of 14 controls (p less than 0.0002). Alcohol abuse related renal changes, similar to those described in humans were present. These included mild mesangial expansion and intense IgA deposition. Foot process effacement was observed in alcoholic animals; severe proteinuria was found in half the animals with IgA nephropathy. This is the first report of chronic ethanol ingestion induced mesangial IgA nephropathy in an animal model.

Alcoholism↗
PubMed1989

Primary penile lymphoma in a patient with Peyronie's disease.

Malignant lymphoma involving the penis is rare, with only 5 cases reported in the literature. We report a case of primary lymphoma of the penis in a 60-year-old white man with Peyronie's disease who underwent ablation followed by brief chemotherapy. There was no evidence of systemic lymphoma involvement 6 years after therapy.

Combined Modality Therapy↗
PubMed1989

Morphological and biochemical changes in the pancreas of the copper-deficient female rat.

Earlier histological studies have demonstrated that copper deficiency results in a selective and progressive atrophy of pancreatic acinar tissue. The present study examined both biochemical and morphological changes of the exocrine pancreas in nutritional copper deficiency. Groups of mature female rats were fed a purified diet either deficient (less than 0.5 micrograms/g) or sufficient (6.2 micrograms/g) in copper for 6 wk. Copper deficiency resulted in distinct ultrastructural changes in acinar cells, including marked variability in zymogen granule content, autophagic vacuoles and dilation of acinar lumen. Pancreatic weight and total DNA, RNA and protein content of the pancreas were similar in both groups of rats, whereas pancreatic amylase, trypsin and chymotrypsin activity was significantly lower in the copper-deficient group. In addition, secretagogue-induced release of these enzymes from dispersed acini isolated from copper-deficient rats was significantly reduced in comparison to enzyme secretion from normal controls. Pancreatic Cu-Zn and Mn superoxide dismutase activity was also found to be significantly lower in the copper-deficient rats than in normal controls. We conclude that nutritional copper deficiency in adult female rats reduces the responsiveness of the pancreas to secretagogues and may increase the susceptibility of the pancreas to oxidative damage.

Animals↗
PubMed1989

Aortic blebs: possible site of aneurysm rupture.

Although the growth and rupture of abdominal aortic aneurysms are commonly explained by Laplace's law, the final events that precede aneurysm rupture are not fully understood. Local excrescences within the wall of abdominal aortic aneurysms were observed in four of five patients studied with preoperative CT scanning, and were removed from six patients at the time of surgery. These protrusions were filled with thrombus, and on histologic examination marked attenuation of the aortic wall, focal loss of elastic fibers, and inflammatory cell infiltrates of lymphocytes, plasma cells, and occasional multinucleate giant cells were seen. The presence of these blebs and their microscopic characteristics suggest their potential as a mechanism for rupture and recognition of this deformity by use of abdominal CT scanning may indicate the necessity for prompt surgical intervention. Further careful clinicopathologic correlation is required to clearly establish these localized defects in the aneurysm wall as a cause for rupture.

Aged↗
PubMed1988

Atypical stromal smooth muscle hyperplasia of prostate.

A prostatic lesion was resected but recurred six years later with the same atypical smooth muscle hyperplasia in the stroma and without glandular atypia. Ultrastructural study confirms the smooth muscle origin and its atypicality. Review of previous reports of leiomyosarcoma of the prostate show that the minimum criteria for malignancy are gross evidence of capsular invasion and one to two mitotic figures per ten high-power field. Cellular pleomorphism and cellularity by themselves are insufficient to diagnose sarcoma.

Aged↗
PubMed1988

Potentiation of ethanol-induced pancreatic injury by dietary fat. Induction of chronic pancreatitis by alcohol in rats.

Effects of sustained ethanol intoxication and dietary fat content on pancreatic morphology were investigated in the rat model implanted with gastrostomy catheters, which permitted continuous intragastric infusion of ethanol plus liquid diet containing one of three levels of corn oil: 5% (low-fat), 25% (high-fat), and 35% (extra-high-fat) of total calories. After various durations of infusion ranging from 30 to 160 days, the pancreatic histology was examined. Mean blood alcohol levels achieved in the low, high, and extra-high fat diet groups were similarly high: 210 +/- 120, 224 +/- 122, and 289 +/- 110 mg/dl. The average weight gain of these ethanol-fed groups during the first 8 weeks of experiments was 15.4 +/- 1.9, 19.6 +/- 8.0, and 14.9 +/- 5.2 g/wk, respectively, and was not statistically different from that of pair-fed controls infused with isocaloric amount of dextrose and respective diet, nor from that of age-matched animals given the regular chow. None of control animals showed abnormal pancreatic morphologic features except occasional mild steatosis in those fed the extra-high-fat diet. With the low dietary intake of unsaturated fat, chronic ethanol intoxication produced only mild pancreatic pathology such as steatosis and interstitial edema. Administration of ethanol and the high-fat and extra-high-fat diets caused hypogranulation and apoptosis of acinar cells. Focal lesions of chronic pancreatitis were also observed in 20% or 30% of ethanol-fed animals given the high-fat or extra-high-fat diet. These lesions were characterized by fat necrosis, mononuclear cell infiltration, fibrosis, acinar atrophy, ductal dilatation, and intraductal mucious or proteinacious plugs. The incidence of focal acute pancreatitis was less (7-20%) but appeared increased with higher dietary fat content. Induction of either acute or chronic pancreatitis was not correlated with plasma levels of triglycerides or cholesterol. These results demonstrate potentiation by dietary unsaturated fat of ethanol-induced pancreatic injury. This model possesses many features analogous to those seen in alcoholic pancreatic injury in man. The hyperlipidemia does not appear to be an important pathogenetic factor for ethanol-induced pancreatitis produced in this model.

Alcoholism↗
PubMed1986

Morphological and biochemical changes of the pancreas in rats treated with acetaldehyde.

Daily intraperitoneal injections of acetaldehyde for 10 days to adult rats produced distinct morphological and biochemical changes in the exocrine pancreas, without affecting the body weight, pancreatic weight, and DNA, RNA, and protein content of the pancreas. By electronmicroscopy, although the number and size of the acinar zymogen granules appeared to be the same between the saline- and acetaldehyde-treated rats, the zymogen granules of the latter group showed decreased osmiophilia. Acinar mitochondria of the acetaldehyde-treated rats were found to be slightly swollen with dense granules, and plasma membrane fragments were often seen in the acinar lumen. Administration of acetaldehyde significantly decreased immunoreactive cationic trypsin (ogen) and total amylase activity in the pancreas, but not in the serum, where amylase activity was markedly increased. Basal secretion of amylase, trypsinogen, and chymotrypsinogen from isolated dispersed pancreatic acini of acetaldehyde-treated rats was increased by 40-50%. Nicotine (5-25 mM) induced a profound increase in secretion of the same enzymes from isolated acini of both saline- and acetaldehyde-treated rats, but in the latter group there was a concomitant rise in LDH release. Furthermore, CCK-8 (1 nM), secretin (1 microM), and carbachol (10 microM) either alone or in combination with nicotine (12.5 mM) produced a profound stimulation in amylase, trypsinogen, and chymotrypsinogen secretion from acini of both groups of rats. On the other hand, secretion of 3H-pulse-labeled proteins from isolated acini of acetaldehyde-treated rats by nicotine was decreased by approximately 50% compared with the controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetaldehyde↗
PubMed1986

Effect of prenatal iron deficiency on myelination in rat pups.

In this study, a histopathologic examination of the brain from iron-deficient or iron-supplemented rat pups was carried out. Pups were obtained from female rats, which were fed an iron-deficient or iron-supplemented diet during both pregnancy and lactation. Immediately after anesthesia and the collection of blood, pups were fixed by intracardiac infusion of 2% glutaraldehyde. Brain and cervical spinal cord were fixed, embedded in paraffin, and cut at 6-mu thickness. Myelin was identified using Luxol fast blue stain. As compared with controls (hematocrit, 30.8%), 11-day-old iron-deficient pups (hematocrit, 11.9%) showed reduced myelination in the spinal cord. Although myelination increased somewhat in the iron-deficient 17-day-old pups (hematocrit, 8.5%), the amount of myelin in the spinal cord and white matter of cerebellar folds was reduced as compared with that of the corresponding controls. These observations show the importance of prenatal iron adequacy in myelinogenesis.

Anemia, Hypochromic↗
PubMed1985

Tinea versicolor: a light and electron microscopic study of hyperpigmented skin.

Hyperpigmentation in lesions of tinea versicolor has previously been reported to be a result of the effects of the fungus Pityrosporon orbiculare on melanosome formation and distribution. Examination of biopsy specimens from lesions of hyperpigmented tinea versicolor involving vitiliginous skin reveals an absence of melanosomes and melanocytes. Reddish-tan and fawn-colored hyperpigmentation in tinea versicolor of this type is not due to melanin pigment. The possible nature of the pigmentation that delineates hyperpigmented tinea versicolor from normal skin is discussed.

Aged↗
PubMed1984

Cytomegalovirus viremia detected by molecular hybridization and electron microscopy.

Fatal cytomegalovirus interstitial pneumonitis developed in a patient with chronic leukemia. The diagnosis was suspected on the basis of cytologic examination of bronchial washings. The virus was subsequently recovered from saliva, urine, and blood leukocytes after 8, 9, and 18 days in culture respectively. Premortem cytomegalovirus DNA was found by molecular hybridization methods using a complete viral genome probe in blood leukocytes after 4 hours' reaction time. Electron microscopic examination showed herpes-like virions consistent with cytomegalovirus in 3% of the patient's granulocytes. Thus, DNA:DNA hybridization and ultrastructural methods can be used for rapid diagnosis of disseminated cytomegalovirus infection.

Aged↗
PubMed1983

Lethal infection with murine cytomegalovirus after early viral replication in the spleen.

In acute lethal murine cytomegalovirus (MCMV) infection the spleen and liver are the principal sites of early viral replication. MCMV titers increase rapidly in the spleen and liver, exceeding 10(6) and 10(5) plaque-forming units (pfu)/g of tissue, respectively, within 96 hr of viral inoculation. Experiments were performed to determine the impact of early splenic viral replication on disease pathogenesis. Splenectomized mice survived acute infection in significantly greater numbers (25 of 34 vs 14 of 33, respectively) than controls and had lower hepatic viral titers (1.9 X 10(4) vs 2.4 X 10(5) pfu/g, respectively). Examination of the spleen by electron microscopy after administration of phagocytic markers demonstrated that macrophages were the predominant site of viral replication. It is concluded that early replication of MCMV in splenic macrophages augments virus-induced hepatic injury and thus contributes to the pathogenesis of lethal MCMV infection.

Animals↗
PubMed1983

Keratosis punctata of the palmar creases.

We report on a 31-year-old man with keratosis punctata (punctate hyperkeratosis) of the palmar creases. We examined a lesion ultrastructurally and were unable with routine electron microscopic techniques to note any significant abnormalities.

Adult↗