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Y Mekori

Publications and source records attributed to Y Mekori.

14 recordsLinked to original sources
PubMed1998

Aberrant crypt foci in human colons: distribution and histomorphologic characteristics.

Aberrant crypt foci (ACF) are one of the earliest putative preneoplastic, and in some cases, neoplastic lesions in human colons. These microscopic lesions, identified on methylene blue-stained mucosa with a low-power-magnification microscope, are thought to be closely related to the earliest steps in multistage colonic tumorigenesis. We investigated the distribution pattern and histomorphological features of ACF in 74 patients with sporadic colorectal cancer. The distribution pattern shows a slightly higher prevalence with older age. The prevalence of the ACF in sigmoid colon was significantly higher in patients with colorectal cancer as compared with patients with benign colonic diseases. Also, significantly more ACF were detected in distal parts of the large bowel (descending, sigmoid colon, and rectum) than in proximal parts. Of 42 microdissected lesions, 12 were dysplastic and 30 were hyperplastic foci. The average size of dysplastic lesions was significantly larger than hyperplastic foci. More apoptotic bodies were found in dysplastic lesions. These lesions also showed an upward expansion of proliferative compartment and higher proliferation indices expressed as proliferating cell nuclear antigen-labeling index. Lymphoid follicles were frequently observed in the base of both hyperplastic and dysplastic foci (40% and 66.6%, respectively). The coincidence of lymphoid follicles was 2.5 to 8 times higher than expected. These features may be related to further progression of selected ACF during colorectal tumorigenesis.

Adult↗
PubMed1997

Proliferating cell nuclear antigen as a marker of cell kinetics in aberrant crypt foci, hyperplastic polyps, adenomas, and adenocarcinomas of the human colon.

BACKGROUND: One of the first steps in multistage colonic carcinogenesis is increased cell proliferation and an upward shift of the proliferation zone of colonic crypts. In the present study, progression in cell kinetics was followed up at all sequential stages of colonic carcinogenesis, starting with aberrant crypt foci (ACF), the earliest putative preneoplastic lesions, hyperplastic and dysplastic polyps, and invasive carcinomas. MATERIALS AND METHODS: Colonic tissue and tumor specimens were prospectively obtained from 65 patients treated at our hospital for adenocarcinoma or malignant polyps. For identification of ACFs, dissected mucosal strips obtained from patients with colorectal cancer were stained with 0.1% methylene blue and scanned under dissecting microscope. Paraffin-embedded ACFs and macroscopic lesions were serially sectioned, deparaffinized, and stained with a monoclonal antiproliferating cell nuclear antigen (PCNA) antibody. The PCNA-labelling index (PCNA-LI), expressed as a ratio of positively stained nuclei to total nuclei counted, was calculated separately for basal, middle, and upper colonic crypt compartments. A comparison of the PCNA-LI was made for each compartment in normal mucosa, and hyperplastic and dysplastic lesions. RESULTS: A stepwise increase in the PCNA-LI was observed during neoplastic progression of colonic lesions. The two most important variables of increased cell proliferation, expressed as PCNA-LI per crypt compartment, were the presence of dysplasia and the size of dysplastic lesions. CONCLUSIONS: In colorectal carcinogenesis, hyperproliferation with upward expansion of proliferative compartment is a characteristic feature at all stages of malignant progression.

Adenocarcinoma↗
PubMed1997

Urticaria in idiopathic bilateral recurrent branch retinal arterial occlusion.

Idiopathic bilateral recurrent branch retinal arterial occlusion (IBRBRAO) is a rare syndrome characterized by migraine headaches, tinnitus, vertigo, hearing loss, and recurrent branch retinal artery occlusion of unknown etiology. Affected patients frequently undergo a wide range of medical evaluation and have no apparent pathologic findings. We present here a case of IBRBRAO, associated with urticarial rash, not described in this syndrome in previous publications.

Adult↗
PubMedDate not supplied

Oncoprotein coexpression in human aberrant crypt foci and minute polypoid lesions of the large bowel.

BACKGROUND: Genetic aberrations observed in the large bowel during the neoplastic progression have a cumulative effect and are responsible for the propagation of the multistep malignant process. In the present study we evaluated the immunoreactivity of c-fos, ras, bcl-2 and p53 in aberrant crypt foci (ACF) and minute polyps of the large bowel obtained from patients with colorectal cancer. METHODS: ACF and minute polyps were collected from macroscopically normal colonic mucosa. Protein immunoreactivity was detected on parafin sections utilizing the biotin-streptavidin method on 25 hyperplastic, 10 dysplastic ACF, 5 hyperplastic and 10 dysplastic adenomas. RESULTS: 41% of the lesions displayed positive ras immunoreactivity. bcl-2 immunoreactivity was positive in six minute polyps of which five were neoplastic. fos immunoreactivity was detected in five ACF and seven minute polyps, mainly in dysplastic lesions. Two neoplastic polyps were positive for p53 immunoreactivity. Coexpression of two or more oncoproteins was found with increasing frequency in dysplastic versus hyperplastic lesions and in polypoid lesions versus ACF. CONCLUSION: Abnormal expression and coexpression in oncoproteins can be identified in the earliest stages of colorectal tumorigenesis and may contribute to the progression of selected lesions during ACF-adenoma-carcinoma sequence.

Colon↗
PubMedDate not supplied

Immunosuppression in vitro and in vivo by supernatants from murine lymphoma cell lines.

Supernatants from four murine B and one T-cell lymphoma cultures were tested for their suppressive effect on allogeneic response in vitro (MLR), on their effect on mitogenic response to ConA and LPS and on their effect in vivo on allogeneic stimulation of BALB/c mice by C57BL/6J spleen cells. Two out of four B-cell supernatants (WEHI-231 and 24-666) were also tested for their effect on induction of IL-2 like activity by ConA in BALB/c spleen cells and on the effect of their injection on subsequent allogeneic response of spleen cells from BALB/c mice immunized against C57BL/6J spleen cells. The supernatants from all lymphoma lines inhibited MLR but only supernatants from the B-cell lymphoma lines also inhibited mitogenic stimulation in vitro and allogeneic immunization. The two B-cell supernatants tested also inhibited induction of IL-2 like activity and decreased the ability of spleen cells from the injected mice to respond to allogeneic stimulation. Partial characterization of supernatants from WEHI-231 and 24-666 lymphoma cultures revealed the non-protein nature of the suppressor factor(s), indicated a molecular weight of less than 5 Kd and suggested a ganglioside or a sialyated glycoproteinic nature.

Animals↗