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Biomedical subjects

R Koren

Publications and source records attributed to R Koren.

122 records · Page 7Linked to original sources
PubMed1975

Interaction of reduced nicotinamide adenine dinucleotide with beef heart s-malate dehydrogenase.

The interaction of NADH with s-malate dehydrogenase isolated from beef heart was studied in 20 mM potassium phosphate (pH 6.9)-1 mM EDTA, with forced dialysis, fluorescence, and temperature-jump techniques. Measurements of the change in fluorescence of NADH when it is titrated with enzyme indicate NADH bound to monomeric and dimeric enzyme have different fluorescence yields. These data and the results of direct binding studies can be explained in terms of a model in which the NADH binding sites on dimeric enzyme are equivalent or nearly equivalent, and NADH binding to monomeric enzyme occurs with an affinity very similar to that of the dimer. However, the fluorescence enhancement of NADH on binding to the enzyme is different for the monomer and for each of the two dimer sites.

Animals↗
PubMedDate not supplied

1,25-Dihydroxyvitamin D3 acts directly on human lymphocytes and interferes with the cellular response to interleukin-2.

1,25-Dihydroxyvitamin D3 (1,25(OH)2D3) inhibits mitogen-induced lymphocyte proliferation in peripheral blood mononuclear cell preparations. Receptors for 1,25(OH)2D3 are present in monocytes and are acquired by lymphocytes upon activation. It is not clear whether the hormone inhibits lymphocyte mitogenesis by a direct action on the lymphocyte or only indirectly by affecting the regulatory monocytes. We addressed this question by using highly purified human lymphocyte preparations which contain less than 0.1% monocytes. 1,25(OH)2D3 inhibited the stimulation of purified lymphocytes by phytohemagglutinin and in the presence of fixed accessory cells, which cannot respond to 1,25(OH)2D3. The inhibitory effect attained 35% similar to that obtained in the presence of monocytes. 1,25(OH)2D3 inhibited interleukin 2 (IL-2)-driven stimulation of purified T cells in three different systems: cells treated with a submitogenic concentration of phytohemagglutinin, IL-2-dependent cells which bear receptors for IL-2 and naive cells in the absence of other mitogens. We conclude: (1) the human T lymphocyte is a direct target for 1,25(OH)2D3; (2) 1,25(OH)2D3 inhibits the response of activated, IL-2-receptor-bearing human T cells to interleukin-2.

Calcitriol↗
PubMedDate not supplied

Brush cytology and biopsy in the diagnosis of colorectal cancer. A comparison.

OBJECTIVE: To determine the usefulness of brush cytology of colorectal lesions as compared to biopsy examination. STUDY DESIGN: One hundred brushing cytologies and biopsies were performed on patients who underwent colonoscopic examination for different symptoms. The cytologic smears were classified into five cytologic diagnostic categories. The histologic diagnoses were adenocarcinoma, adenoma and nonneoplastic lesion. RESULTS: Twenty-six cases were cytologically positive for malignant cells, and all were histologically diagnosed as adenocarcinoma. Nineteen cases were suspicious for malignancy on cytology; histologically, eight of them showed adenocarcinoma. Two other cases proved to be adenocarcinoma in subsequent biopsies. Nine cases were adenomas, with severe dysplasia in five of them. Fourteen cases that were cytologically negative with minimal glandular atypia showed seven adenomas and seven nonneoplastic lesions on biopsy. Forty cases negative for malignant cells showed 19 adenomas and 21 nonspecific changes in the biopsy examination. CONCLUSION: Colonoscopic brushing cytodiagnosis is a sensitive technique for the detection of colorectal cancer. The combination of brushing cytology and biopsy improves the accuracy of diagnosis.

Adenocarcinoma↗
PubMedDate not supplied

Lymph node revealing solution: a new method for lymph node sampling: results in gastric adenocarcinoma.

Staging of gastric carcinoma depends on exact lymph node status. However, very small nodes are not easily found as they are obscured by the surrounding adipose tissue. The purpose of the present study was to demonstrate the usefulness of a Olymph node revealing solutionO (LNRS) in gastric cancer. The perigastric adipose tissue of ten OproblematicO cases of gastric carcinoma, in which <10 lymph nodes were found using the traditional method, was immersed in LNRS for 6-12 h. Subsequently, the lymph nodes stood out as white chalky nodules. They were excised and processed routinely. The traditional method yielded a total of 30 lymph nodes with a mean size of 6.69 +/- 3.43 mm. The LNRS revealed 89 additional nodes with a mean size of 3.03 +/- 3.43 mm, which was significantly smaller. The Node (N) stage was changed in four cases from Nx to N0, in one case from N1 to N2, and in one case from N0 to N2. LNRS seems to be the technique of choice for staging of patients with gastric adenocarcinoma in whom <10 lymph nodes were found with the traditional method and accurate staging was not possible.

Adenocarcinoma↗
PubMedDate not supplied

Nucleolar organizer regions in conjunctival nevi and melanomata.

The objective of this study was to compare the argyrophil nucleolar organizer region (Ag-NOR) counts of conjunctival nevi and melanomata and to compare the efficacy of this method in their differential diagnosis. Nine histologically diagnosed conjunctival nevi and three conjunctival malignant melanomas were studied. Representative sections were stained using the AgNOR technique. Fifty cells of each melanocytic lesion were randomly selected without knowing their histologic diagnosis. The AgNORs were visualized at a magnification of x1000. They consisted of clusters >1 micron in diameter and of satellites <1 micron in diameter, which were counted and recorded for each cell separately. The mean AgNOR count for the nevi was 1.12 clusters and 1.72 satellites per cell, while the count for the melanomas was 1.6 clusters and 6.8 satellites per cell. These results are statistically significant. There was no overlap between the number of AgNOR clusters and satellites in conjunctival nevi and melanomas, indicating that the AgNOR count might be a useful tool in distinguishing benign from malignant conjunctival melanocytic lesions.

Adolescent↗
PubMedDate not supplied

Histological changes in the cervical lymph nodes after radiotherapy.

Radiotherapy to the neck is frequently employed in the treatment of malignancies, sometimes alone and sometimes before or after surgery or with or without chemotherapy. We checked the histopathological changes in the neck after radiotherapy, dividing the changes into two groups. One with short-term changes between six months to one year, and the second group with long-term changes after more than six years. We compared these two groups with a control group without radiotherapy. The changes in the long-term group were more pronounced than in the short-term group, with more stromal fibrosis, vascular changes, and specially lymph nodes smaller than one centimeter. Thus, bigger lymph nodes (more then one centimeter) are more radiosensitive and become smaller after six years.

Adult↗
PubMedDate not supplied

Intra-articular hyaluronan injections for the treatment of osteoarthritis of the knee: a randomized, double blind, placebo controlled study.

OBJECTIVE: Hyaluronic acid (HA) polymers have been found to be useful as viscosupplements for the treatment of osteoarthritis (OA) in a number of clinical studies. It appears that HA with high molecular weights (HMW) are more effective than low molecular weight HA polymers. METHODS: A single blind, initial randomized study was conducted involving two randomly selected patient groups, which received injections of either placebo or BioHy, a highly purified HMW HA produced by bacterial fermentation. HA was administered intra-articularly and several functional tests, including pain level, stiffness, and physical function, were used to score efficacy at various intervals throughout the study. RESULTS AND CONCLUSION: The results through week 20 indicate that BioHy provides relief for osteoarthritic patients without causing adverse effects, although the study was not sufficiently powered to obtain statistically significant differences between the treatment groups.

Adjuvants, Immunologic↗
PubMedDate not supplied

Human prostatic tissue constituents respond differently to thermal injury induced by Nd-YAG laser ITT fiber applied ex-situ.

BACKGROUND AND OBJECTIVE: The human prostate is a glandular organ that has intervening fibromuscular elements. The objective of this study was to evaluate the thermocoagulative effect on the different components of the organ exposed to Nd-YAG laser irradiation using a new ITT optic fiber design (Interstitial Thermal Therapy). STUDY DESIGN/PATIENTS AND METHODS: Twelve fresh transvesical prostatectomy specimens were irradiated ex-situ at 4 to 6 sites using an ITT fiber with laser energies ranging from 900 to 4500 joules (J) applied at times ranging from 60 to 300 seconds corresponding to 10 to 15 watts. The specimens were serially sectioned to include the proximal, mid and distal regions of the centrally coagulated channel. An ocular grid was utilized to measure the radius (r) of thermal injury from the margin of the centrally coagulated channel to the furthermost detectable area of thermally induced changes. RESULTS: The maximal extent of thermal injury was seen at the mid-length of the irradiated channel at energy of 2700 J (15w/180 sec). The fibromuscular compartment of the prostate was more affected (r = 855 microm) and showed more interstitial vacuolization and charring than the adenomatous one (r = 495 microm). Utilization of higher energy doses did not significantly alter the depth of injury but did reduce the extent of interstitial vacuolization of both components. CONCLUSION: The study indicates that the extent of laser induced coagulative necrosis depends on the histologic architecture of the prostate and also varies in extent along the length of the channel surrounding the fiber.

Dose-Response Relationship, Radiation↗
PubMedDate not supplied

Prognostic significance of p53 and ras p21 protein expression in surgically treated non-small cell lung carcinoma.

BACKGROUND AND OBJECTIVE: The prognosis of surgically treated non-small cell lung carcinoma (NSCLC) varies even after careful selection of the patients; the conventional grading and staging system is often deficient in determining which cases will profit best from surgery. Additional techniques are needed to permit better prognostic evaluation. METHODS: In this research, 2 markers of cellular proliferation, p53 and ras (p21) proteins were examined. The material used was from the same series reported previously which were immunostained with different cytokeratin markers for the same purpose. Immunohistochemical stainings of p53 and p21 were performed on the paraffin sections of 88 NSCLC specimens: 45 squamous cell, 22 adeno- and 21 large or undifferentiated carcinomas. RESULTS: At stage I, positive or negative stains of p53 and p21 provided no prognostic information since they had similar 5 year survival rates of approximatively 50% which is similar to the mean predicted survival rate for stage I. In this group as well, there was no significant difference in immunostaining, either in relation to the histological type or grade of the tumors. At stage III-IV, we found a trend, which, however, was not statistically significant, between positive immunostains of p53 and p21 proteins and longer survival. CONCLUSIONS: These results vary from our previous study on the expression of the differentiation marker cytokeratin 18, which showed that positive staining of tumor cells was associated with a statistically significant poorer prognosis at stage I regardless of histological types.

Aged↗
PubMedDate not supplied

Localized amyloid tumor of the tongue. A case report and review of the literature.

Amyloid is usually deposited in the tongue, as a part of generalized amyloidosis. Isolated localized amyloidosis of the tongue is relatively rare. We report such a case which presented with glossodynia and glossopyrosis and was thought clinically to represent median rhomboid glossitis. Histologically the amyloid stained positively with Congo-red giving green birefringence under polarized light, was not abolished after permanganate pretreatment and did not react immunohistochemically for amyloid A, beta 2 microglobulin and transthyretin.

Adult↗
PubMedDate not supplied

Initial TPS serum level as an indicator of relapse and survival in colorectal cancer.

BACKGROUND: Tissue polypeptide specific antigen (TPS) measures a soluble fragment of cytokeratine 18 and may be regarded as a proliferative marker. MATERIALS AND METHODS: TPS was measured in 173 consecutive patients with colorectal cancer. Median follow up time was 36 months. Of 137 evaluable patients 39 developed metastases (P.D.) and 98 remained with no evidence of disease (N.E.D.). RESULTS: Initial TPS levels were elevated in 75% of P.D. patients compared to 32% of N.E.D. patients (p < 0.001), CEA levels were elevated in 26% of P.D. patients had elevated initial TPS compared to 35.5% of N.E.D. patients (p < 0.001), CEA was elevated in 33.3% of the P.D. patients compared to 1.3% of N.E.D. patients (p < 0.001). Survival and disease free survival were significantly shorter for patients with initial high TPS level. TPS was more sensitive than CEA in predicting relapse. CONCLUSIONS: These preliminary data suggest that TPS may be a prognostic factor for relapse and may help to allocate Dukes'B2 patients for adjuvant chemotherapy.

Adult↗