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Biomedical subjects

M Sibony

Publications and source records attributed to M Sibony.

28 records · Page 2Linked to original sources
PubMed1995

Expression of p53 protein related to the presence of human papillomavirus infection in precancer lesions of the larynx.

The aim of this study was to gain some insight into the relationship of human papillomavirus (HPV) infection to p53 expression and to some pathological parameters in precancerous lesions of the larynx. Formalin-fixed paraffin-embedded tissue sections containing human laryngeal precancerous lesions were screened for p53 protein by immunohistochemistry with the monoclonal antibody DO7 and for the presence of HPV infection by polymerase chain reaction with consensus primers directed against the E6 gene. The presence of p53 protein was detected in 31 of 57 specimens (54.4%) including 7 of 9 cases with mild dysplasia (78%), in 4 of 9 cases with moderate dysplasia (44%), and in 15 of 23 cases with severe dysplasia (65%). Of 16 samples with keratotic benign squamous metaplasia, 5 were also p53 positive (31%). Of 6 samples that were HPV positive, all were of type 16. Interestingly, 3 of the 6 HPV-positive samples were p53 negative. There was 1 HPV-positive case with strong p53 staining and 2 HPV-positive cases with minimal p53 staining. The 2 HPV-positive cases with minimal p53 staining had mild dysplasia. The HPV-positive case with strong p53 staining displayed severe dysplasia. Of 23 cases that were both HPV and p53 negative, 11 presented with keratosis and no dysplasia, 5 with moderate dysplasia, and 7 with severe dysplasia. Our data indicate that nuclear accumulation of p53 protein, presumably resulting from p53 gene mutation, may occur in HPV-infected epithelial tissues. On the other hand, there are many precancer lesions, some exhibiting moderate or severe dysplasia, that are both HPV negative and p53 unreactive, suggesting that alterations of genes other than the E6 oncogene and the p53 tumor suppressor gene play a role in early laryngeal carcinogenesis.

Adult↗
PubMed1994

Angiotensin-converting enzyme in murine testis: step-specific expression of the germinal isoform during spermiogenesis.

Angiotensin I-converting enzyme (ACE) is known primarily as an endothelial enzyme that plays a critical role in the regulation of blood pressure. Another, shorter isoform of ACE is abundantly expressed in the testes of sexually mature animals. Using antibodies for immunoperoxidase detection and [35S]-labeled riboprobes for in situ hybridization (ISH), we studied the temporal expression and cell distribution of this germinal isoform of ACE in the testis of normal mice and rats as well as of pubertal and sterile mice. In both murine species, specific testicular ACE mRNA and its gene product are present only after completion of meiosis. Through studying two murine species in which spermatogenesis and spermiogenesis have been accurately described, as well as immature and sterile animals, it could be shown that ACE mRNA and its corresponding protein are first synthesized during the cap phase (steps 4-7). The maximum expression occurred during the acrosome phase (steps 8-12). ACE mRNA is no longer detectable in spermatids beyond step 14, whereas its gene product is expressed until the end of spermatid maturation. Therefore, ACE is exclusively produced in haploid germ cells and belongs to the growing family of proteins whose expression during definite maturation steps of spermiogenesis appears to be correlated with the unique process of germ cell differentiation.

Amino Acid Sequence↗
PubMed1994

Tissue-specific expression of type 1 angiotensin II receptor subtypes. An in situ hybridization study.

The angiotensin II type 1 (AT1) receptor in murine species exists as two isoforms (AT1A and AT1B) encoded by two different genes. Both subtypes have a 9/10 homology in the coding sequence of their mRNA. We examined organs of adult rats (liver, pituitary gland, adrenal gland, kidney, heart, and lung) to study the differential expression of these two genes in target tissues for angiotensin II. AT1A and AT1B mRNAs were detected by in situ hybridization using specific riboprobes for the 3' noncoding region of the mRNAs that have the lowest homology (approximately 6/10). Only AT1A was expressed in the liver, heart, and lung, and only AT1B was expressed in the anterior pituitary, where most cells were positive. In the adrenal gland, AT1A mRNA was detected in the zona glomerulosa and medulla and AT1B in the glomerulosa. In the kidney, AT1A mRNA was the predominant isoform (mesangial and juxtaglomerular cells, proximal tubules, vasa recta, and interstitial cells), but AT1B was also detected in mesangial and juxtaglomerular cells and in the renal pelvis. The results of this in situ detection suggest a tissue-selective regulation of AT1A and AT1B mRNAs. This tissue specificity may constitute a prerequisite condition if the two angiotensin II receptor subtypes, which are pharmacologically similar, are to selectively modulate the various effects of angiotensin II in the different target tissues.

Adrenal Glands↗
PubMed1994

Gonadal and adrenal catheterization during adrenal suppression and gonadal stimulation in a patient with bilateral testicular tumors and congenital adrenal hyperplasia.

We report the case of a patient with bilateral testicular tumors and congenital adrenal hyperplasia due to 21-hydroxylase deficiency. Catheterization of the left testicular and adrenal veins was performed. The presence of 11 beta-hydroxylated steroids in the spermatic veins confirmed the presence of testicular tumor secondary to adrenal rest cells. After adrenal suppression by dexamethasone combined with gonadal stimulation with hCG, a dramatic decrease in androgens and adrenal steroids was observed in the peripheral blood. Compared to the periphery, 21-deoxycortisol and 11 beta-hydroxy-delta 4-androstenedione levels remained higher than that of 21-deoxycorticosterone in the gonadal vein, but not in the adrenal vein, which seems to indicate that the nature of this ectopic tissue is unusual and that its sensitivity to dexamethasone depends on the adrenocortical zones. No rise in estradiol or testosterone was obtained after hCG stimulation, suggesting that all of the testicular tissue was inactive or destroyed. This finding was confirmed by histological examination.

Adrenal Glands↗
PubMed1994

[Prevalence and characteristics of anti-tissue antibodies in chronic hepatitis caused by hepatitis C virus].

OBJECTIVES: The prevalence and significance of antiorganelle antibodies in the serum of patients with chronic hepatitis C is a subject of controversy. We studied prospectively these characteristics in patients with chronic hepatitis C. METHODS AND RESULTS: Among 156 patients (age: 55 +/- 14 years; 83 females), 30 (19%) had significant titers of antiorganelle antibodies: anti-nuclear antibodies in 18, anti-smooth muscle antibodies in 8 (no anti-actin or anti-vimentine subtypes), anti-LKM1 in 2, type 2 anti-mitochondrial antibodies in 2 patients. Anti-organelle antibodies were not detected in 126 patients. Patients with anti-organelle antibodies were significantly older but no difference was found between the two groups for sex ratio, serum amino-transferases or gammaglobulins, histopathological liver activity or prevalence of lymphocytic sialadenitis. The presence of anti-organelle antibodies was not related to HLA phenotype, especially B8 DR3, or DR4. Response to alpha interferon, estimated by serum aminotransferase levels after six months of treatment, was the same in both groups. CONCLUSIONS: These results suggest that serum anti-organelle antibodies are prevalent in during chronic hepatitis C but do not indicate a distinct autoimmune mechanism. Furthermore, the typing of anti-smooth muscle antibodies might help distinguish chronic hepatitis C from type 1 autoimmune chronic hepatitis.

Adult↗
PubMed1994

[Secondary sclerosing cholangitis and chemo-embolization with lipiodol].

Two cases of sclerosing cholangitis after oily arterial chemoembolization are reported. In one patient angiocholitis with liver abscesses, in the other patient gradual cholestasis were the main clinical features. In both cases, endoscopic retrograde cholangiogram showed a stricture of the common hepatic bile duct and, in one case, irregularities of intrahepatic biliary tree. Histologic examination of the liver in the two patients pointed out the involvement of small bile ducts and arteriolar endarteritis obliterans. Ischaemia is likely to be the main mechanism of these two cases of sclerosing cholangitis as well as in those described after FUDR intra-arterial chemotherapy. The prevalence of sclerosing cholangitis after arterial oily chemoembolization is probably underestimated because of a non specific clinical presentation and need to be precise by further study.

Carcinoma, Hepatocellular↗
PubMed1993

Gene expression and tissue localization of the two isoforms of angiotensin I converting enzyme.

Angiotensin converting enzyme exists in two different isoforms, somatic and germinal, whose respective distributions and intracellular localizations have not been precisely determined. The differing biochemical and molecular characteristics of the two isozymes allowed the preparation of antibodies specific for each of the two angiotensin converting enzyme isoforms and of two nucleic acid probes, one of which was specific for the germinal isoform. Immunohistochemistry and in situ hybridization were used to determine the cell distribution of, respectively, the two isoforms and their corresponding messenger RNAs in the classically studied tissues of male adult humans and marmosets. Results provided by the two different methods were always concordant and were identical in the two species. The somatic angiotensin converting enzyme form was expressed uniquely in somatic tissues (vascular endothelial cells and at the brush border of renal proximal convoluted tubule, jejunal villus, and epididymal duct epithelia), and the germinal form was expressed uniquely in germinal cells with a precise stage-specific pattern, starting in round spermatids and finishing in spermatozoa. In situ hybridization documented the presence of somatic angiotensin converting enzyme messenger RNA in renal tubule epithelium, jejunal enterocytes, and epididymal epithelium and demonstrated that there was no direct correlation between the levels of angiotensin converting enzyme messenger RNA and the enzyme it encodes for, i.e., angiotensin converting enzyme, in a given epithelium. The significance of the ultraselective expression of germinal angiotensin converting enzyme and of its specific messenger RNA at a very precise stage of spermatogenesis remains uncertain.

Animals↗
PubMedDate not supplied

Malignant Leydig cell tumor of the testis associated with Klinefelter's syndrome.

We reported the case of a 35-year-old man with Klinefelter's syndrome and a malignant Leydig cell tumor of the testis. Bilateral gynecomastia and right testicular enlargement led the patient to seek medical assistance. Despite initial orchidectomy two years later the patient developed lung and iliac lymph node metastases. The tumor appeared to be refractory to chemotherapy and to hormonal treatments including op'DDD. Finally, the patient died within 20 months of developing metastases. Leydig cell tumor is an exceedingly rare tumor, especially when associated with Klinefelter's syndrome. This association as well as presentation, pathologic features, hormonal abnormalities, clinical course and response to therapy of malignant Leydig cell tumors are discussed.

Adult↗