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B Monis

Publications and source records attributed to B Monis.

At least 19 recordsLinked to original sources
PubMed1993

Promoting effects of mancozeb on pancreas of nitrosomethylurea-treated rats.

UNLABELLED: Rats were treated with a single i.p. injection of the carcinogen nitrosomethylurea (NMU, 50 mg/kg b.w.) at day three of age. The treatment induced hyperplastic and atypical acinar cell proliferation [focal acinar cell hyperplasia (FACH)]. In this investigation, NMU treated rats were fed AIN-76 diet containing mancozeb (MZ; 100 mg/kg diet), a polymeric complex of ethylene bis (dithiocarbamate) manganese with zinc salt, which is an agricultural fungicide. EXPERIMENTAL DESIGN: Group one was treated with NMU plus MZ (MZ-NMU), group 2 received NMU alone (NMU), group 3 was fed MZ and saline injected (MZ-SAL) and group 4 was the saline injected control (SAL). Rats were killed at week 24 of age. In MZ-NMU group pancreas there were FACH, dysplastic foci (DYF) and carcinomas in situ (CIS). FACH were larger, coalescent and may show areas of undifferentiated cells (focus within focus). DYF contain proliferative acinar and ductular structures with loss of polarity but no malignant traits. CIS had medullary appearance or consisted of irregularly shaped acini and ducts in stromal framework. Cell had scant cytoplasm and large hyperchromatic, pleomorphic nuclei. DYF and CIS were not seen in MZ group pancreas. The MZ-NMU group had increased mitotic index and greater number of apoptotic cells. There was no pathologic change in MZ-SAL group. Our data indicated that MZ did not cause pancreatic cell proliferation in normal rats whereas it had distinct promoting and progressor effects on NMU initiated pancreatic cells. Thus, a two-stage protocol of pancreatic carcinogenesis was achieved. It is suggested that the NMU protocol may be useful for testing promoter, progressor or inhibitory effect of chemical and physical agents on cell proliferation and transformation of rat pancreas.

Animals↗
PubMed1991

Multicentric focal acinar cell hyperplasia and hepatocyte-like cell metaplasia are induced by nitrosomethylurea in rat pancreas.

The present report is a study of the effect of the carcinogen nitrosomethylurea (NMU) on pancreas of rats receiving during lifetime a lipid-poor diet, that is essential fatty acid deficient or control diets. Rats fed a commercial stock chow were mated. At day 10 of pregnancy, dams were divided into three groups, that were respectively supplied with the commercial chow, the essential fatty acid deficient or the sufficient diet. Each litter was separated at random in two groups that received at day one of life one intraperitoneal injection of NMU (50 mg/kg b.w.) or saline. After weaning, they were maintained for life with the diet that was supplied to their mothers. The pancreas of NMU-treated rats presented diffuse proliferative changes, focal acinar cell hyperplasias (FACH), and focal hepatocyte-like metaplasia (FHLCM). FACH were expansive presumably preneoplastic growths, showing abnormal differentiation. The number of NMU-treated rats bearing FACH and FHLCM did not significantly differ in the three nutritional conditions.

Animals↗
PubMed1990

Postnatal ontogeny of gamma glutamyltranspeptidase activity of pancreas in essential fatty acid deficient rats treated with nitrosomethylurea.

The effect of essential fatty acid deficiency and nitrosomethylurea treatment on postnatal levels of pancreatic gamma-glutamyltranspeptidase was studied. A significant increase of gamma-glutamyltranspeptidase activity and changes in fatty acid composition were observed in essential fatty acid deficient rats, from the 14th day of life on. Pancreatic gamma-glutamyltranspeptidase of nitrosomethylurea injected rats in essential fatty acid deficiency and controls was significantly diminished at the 30th day, with no significant differences in both nutritional conditions. The results indicated: 1. Concomitant changes in gamma-glutamyltranspeptidase activity and fatty acid composition of rat pancreas in essential fatty acid deficiency, 2. A significant reduction of pancreatic gamma-glutamyltranspeptidase activity following a single intraperitoneal injection of nitrosomethylurea at day one of life and 3. No interacting effects of essential fatty acid deficiency and nitrosomethylurea on gamma-glutamyltranspeptidase activity of rat pancreas.

Animals↗
PubMed1990

A Feulgen microspectrophotometric study of the DNA content of essential fatty acid-deficient rat pancreas treated with nitrosomethylurea.

Microspectrophotometric DNA measurements in exocrine pancreas of essential fatty acid-deficient (EFAD) and EFA-sufficient (EFAS) rats which received a single intraperitoneal injection of the carcinogen nitrosomethylurea (NMU) or saline (SAL) was the subject of the present report. The DNA content of acinar pancreatic cells of SAL-injected EFAD and EFAS rats was diploid. NMU-induced pancreatic focal acinar cell hyperplasia (FACH) had one main cell population with a diploid content, whereas in the intervening parenchyma there were diploid and tetraploid cells. The number of tetraploid cells was smaller in EFAD rat pancreas than in EFAS indicating a diet dependent effect. NMU-induced FACH had a diploid distribution pattern indicating that cells are in a G1, quiescent phase, contrasting with AZA-induced similar lesions which showed an abnormal ploidy. It remains to be established whether DNA phenotypic traits of NMU and AZA induced FACH reflect the neoplastic potentials of both types of lesions. The decreased number of tetraploid cells in EFAD rat pancreas is in keeping with data indicating a promoting effect of the EFA linoleic and arachidonic acids on growth rate of certain cell populations in vitro.

Animals↗
PubMed1987

Carrageenan induces anomalies in the chick embryo. A light microscopic study.

Chick embryos injected with lambda-carrageenan prior to incubation and studied with light microscopy at 48 hours of development presented various anomalies. Lack of closure at different levels of the neural tube was one of the lesions most frequently seen. Rachischisis and craniorachischisis were commonly associated with various degrees of hyperplasia of the neural tube wall. Diverse patterns of neural hyperplasia ranged from total occlusion of the neural tube to localized thickening of lateral walls leading to a typical "hourglass" appearance of the ependymal lumen. Multiple septa and cavitations of the neural tube lumen were also recorded. Cephalic and/or trunk duplication of the body as well as disorganization of notochord and somites were frequently associated with rachischisis and areas of necrosis or pyknosis of neural tissue. Neural crest cells, which are normally present in paraneural areas at the stages studied, were not encountered in the carrageenan-injected embryos. These areas were frequently occupied by hyperplastic ectodermic folds. Similarity of present findings on carrageenan-treated embryos with the anomalies induced by selective destruction or impairment of migration of neural crest cells suggests that involvement of this cell population may have a role in the causation of the anomalies observed.

Animals↗
PubMed1986

Ultrastructure of macrophages of carrageenan granuloma in the rat with data on gamma-glutamyltranspeptidase activity.

The present study is an electron-microscopic investigation of granuloma induced in the rat by the subcutaneous injection of 1% lambda-carrageenan in 0.8% sodium chloride. We report on the presence of desmosome-like structures connecting neighbouring macrophages. They consisted of electron-dense plaques, which are closely applied to the cytoplasmic surfaces of the junction. Usually, no bundles of cytoplasmic filaments attached to the plaques were seen. At the intercellular space at the level of the junction, a dense material was observed that was sometimes arranged in a cross-bridge fashion. The lysosomal system was markedly developed and consisted mainly of secondary lysosomes containing a filamentous material that showed intense acid phosphatase activity, which was also demonstrated in Golgi cisternae. A membrane preparation obtained from rat carrageenan granuloma contained gamma-glutamyltranspeptidase activity (GGTP), which is a cell and lysosomal membrane-bound enzyme. The GGTP activity of a similar membrane preparation of guinea pig carrageenan granuloma was six times higher than that of the rat.

Animals↗
PubMed1986

Ultrastructural variations of the urothelial membrane in essential fatty acid (EFA)-deficient rats. A digital densitometric study.

The present report deals with a densitometric study of the ultrastructural images of the urothelial membrane of rats in the following experimental conditions: (1) EFA-deficient (EFAD) rats; (2) EFA-sufficient (EFAS) rats; and (3) EFAD rats that were fed the EFAD diet for 30 weeks and received an EFAS diet for the following 10 weeks (EFAD/S group). On electron micrographs of the transitional epithelium of ureters and urinary bladder of these rats, optical density (OD) profiles of the urothelial unit membrane were recorded and digitized using a computer-controlled microdensitometer with a solid-state self-scanned photodiode array sensor. A Gaussian curve was adopted as a model for the distribution of electron-dense material in each osmiophilic leaflet. Gaussian parameters were used to estimate the thickness of the urothelial membrane and of each osmiophilic leaflet, and the amount of electron-dense material and the maximal electron density present in each leaflet. In EFAS rats, the thick urothelial membrane was asymmetric like that of the normal, resulting from a greater thickness of the outer leaflet and a greater electron density of the cytoplasmic one. In EFAD rats, a loss of the characteristic ultrastructural asymmetry and a decrease of the total thickness of the unit membrane were detected. These changes were partially reversed in the EFAD/S rats.

Animals↗
PubMed1983

Concanavalin A sites in urothelium and milk fat globules of essential fatty acid (EFA) deficient rats.

We studied the ultrastructural distribution of Concanavalin A sites of urothelial and milk fat globule membranes in situ in EFA-deficient and control rats using the peroxidase-diaminobenzidine procedure in unfixed and glutaraldehyde-fixed materials and incubating temperatures of 4 degrees C and 37 degrees C of the Con A media. In the glutaraldehyde ('prefixed') bladders the lectin marker was homogeneously distributed at the surface of the urothelial membrane with no difference between experimental and control animals. In unfixed bladders ('non-prefixed') of EFA-deficient rats, Con A sites distribution was also homogeneous and similar to that observed in 'prefixed' bladders. In bladders of controls in the 'non-prefixed' condition incubated at both 4 degrees and 37 degrees C, there was a noticeable change in the distribution of Con A sites consisting in a distinct clumping of Con A sites. In 'prefixed' and 'non-prefixed' cream samples of both EFA-deficient and control animals, there was a similar, uniform distribution of Con A sites at the surface of the milk fat globule membrane. The reported changes seemed to suggest that the fluidity of the urothelial membrane but not of milk fat globules was diminished in EFA-deficient rats. Present data do not permit evaluation of the role of cytoskeletal components and/or the variations of the fluidity of the membranes on the distribution of Con A sites at cell surfaces, as herein reported.

Animals↗
PubMed1981

Teratogenic effect of lambda-carrageenan on the chick embryo.

Carrageenans are widely used as food additives. Thus, it seemed of interest to test their possible teratogenic action. For this purpose, 530 chick eggs were injected in the yolk sac with 0.1 ml of a solution of 0.1% lambda-carrageenan in 0.9% sodium chloride. As controls, 286 eggs were injected with 0.1 ml of 9.0% sodium chloride. In addition, 284 eggs received no treatment. After incubation for 48--50 hours at 39 degrees C, embryos were fixed, cleared, and observed with a stereoscopic microscope. The frequency of abnormal embryos in the group receiving lambda-carrageenan was higher than in the controls (p less than 0.04). Partial duplication of the body, abnormal flexures of the trunk, anencephaly, a severely malformed brain, thickening of the neural tube wall, an irregular neural tube lumen with segmentary occlusion and a reduction in crown-rump length and number of somites were distinctly seen in the lambda-carrageenan-injected group. Moreover, the average number of anomalies per embryo in the lambda-carrageenan-injected group was nearly twice that in the controls. Present data indicate that lambda-carrageenan has teratogenic effects on early stages of the development of the chick embryo.

Abnormalities, Drug-Induced↗
PubMed1980

Histochemistry of glycoconjugates of pleomorphic adenomas of minor salivary glands, with special reference to glycocalyx of tubular areas.

Histochemical characterization of glycoconjugates elaborated by palatal pleomorphic adenomas showed that glycoproteins, glycosaminoglycans, and perhaps glycolipids were present in both the "epithelial" and "connective tissue" components of these tumors, as well as in the distinct glycocalyx present in the luminal surface of tubular and cystic areas.

Adenoma, Pleomorphic↗
PubMed1980

Incidence of urothelial tumors in rats deficient in essential fatty acids.

Wistar rats were fed a diet deficient in essential fatty acids (EFA). Control animals received the same diet to which was added 5% corn oil, a source of EFA. The experimental group showed clinical and chromatographic evidences of EFA deficiency. Groups of deficient and control animals were killed at various periods up to 100 weeks of age. Of 43 EFA-deficient rats, 8 (18.6%) had papillary transitional cell tumors of the urinary tract. None of the 36 controls had tumors (P less than 0.01). In 7 animals, tumors were found in the renal pelvis and upper portion of the ureter; in one, the tumor was in the bladder. The tumors were more frequent at the end of the first year of life and after the first year of life, with no significant sex differences. Tumors showed various degrees of differentiation and a trend toward bilateral involvement. Subepithelial and muscle invasion of tumor was noted in 5 rats. Most tumors were polycentric, and carcinomas in situ were seen. Atypical hyperplasias were found in 35% of the EFA-deficient rats and in 3% of the controls. Typical hyperplasias were seen in 63% of the EFA-deficient rats and in 72% of the controls, Renal calcifications, congestion, inflammation, and hydronephrosis were also seen. No significant differences other than congestion were found in both groups. Our results suggest that the mechanisms regulating proliferation of urothelial cells are upset in EFA-deficient rats; this favors the appearance of atypical hyperplasias and tumors. Therefore, EFA deficiency in the rat may be a useful model for the study of the causes and pathogenesis of human urothelial cancer.

Animals↗
PubMed1979

Glycosaminoglycans of the plasma membranes of renal tubule and liver cells.

Glycosaminoglycans were isolated from plasma membranes of hepatic and renal tubule cells of guinea pig. Plasmalemma of renal tubule cells contained more total glycosaminoglycans, hyaluronic acid, chondroitin-4 sulfates and chondroitin-6 sulfates, and less dermatan sulfates and heparin sulfates than liver plasma membranes. These glycocalyx components, owing to their polyanionic properties, may have a role in the transport of water, ions, and macromolecules across the cell membrane.

Animals↗
PubMed1976

Ultrastructural changes of the luminal plasma membrane of the transitional epithelium of the rat urinary tract in essential fatty acid deficiency.

Rats fed an essential fatty acid deficient diet (EFAD) showed a statistically significant decrease in the thickness and ultrastructural asymmetry of the luminal membrane and cytoplasmic vesicles of transitional epithelium of the urinary tract, due to a marked thinning of the peculiar thick luminal leaflet. These changes were reversed by adding EFA to the diet. This indicates that the unusual EM appearance of urothelial membrane depends on its content in EFA.

Animals↗