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Biomedical subjects

M M Stein

Publications and source records attributed to M M Stein.

6 recordsLinked to original sources
PubMed2000

Immunostaining and laser-assisted cell picking for mRNA analysis.

Isolation of single cells or cell clusters from complex tissue sections has become possible by microdissection techniques. Employing laser-assisted cell picking, cell-specific mRNA analysis of a few isolated cell profiles may be performed. However, microscopic discrimination of different cell types in routinely stained tissue sections is limited, whereas immunostaining enables a more precise access to cells of interest. This approach was noted to interfere with mRNA recovery. To define optimal conditions for mRNA amplification from immunodetected cells, we systematically investigated several potential affectors. Kind of fixation, antibodies and staining reagents, incubation and total processing time, and digestion with proteinase K turned out to influence mRNA stability. We present rapid protocols for immunohistochemistry and immunofluorescence with total incubation times of approximately 25 to 40 minutes and 10 to 20 minutes, respectively, and suggest mRNA amplification without a preceding extraction step. Applying these protocols to oligocellular clusters containing approximately 20 cell profiles and nuclei each from lung and kidney tissue, the highest efficiency rates of mRNA amplification were obtained when combining short-term formalin fixation, reduction of antibody incubation time, application of immunofluorescence, and digestion with proteinase K. Thus, the successful combination of immunostaining and laser-assisted cell picking remarkably improves cell type-specific analysis of gene expression within complex tissues.

Alkaline Phosphatase↗
PubMed1999

Unusual sonographic appearance of an epidermoid cyst of the testis.

Epidermoid cyst of the testis is a rare benign testicular tumor with varied sonographic appearances. We present a case in which two specific ultrasonographic patterns were seen: (1) an "onion ring" configuration of alternating hyperechoic and hypoechoic regions, described previously as being characteristic of this lesion, and (2) a heterogeneous region with multiple punctate hyperechoic foci.

Adult↗
PubMed1997

Relationship between left-handedness and allergic symptomatology.

Handedness and health parameters were assessed in 70 infants. Video recordings were employed for handedness analysis. The infants' growth and health were periodically followed up from birth and information was retrieved from medical records. A significant association between left-handedness and allergy score was found (P < .05). Age (P < .02) and sex (P < .01) appear to be significant covariates. It appears that the possible association between left-handedness and immune-based diseases among adults applies to infants as well. A possible biologic marker for allergy should be incorporated in future research.

Age Factors↗
PubMed1987

Mechanism of slow-binding inhibition of human leukocyte elastase by trifluoromethyl ketones.

Kinetics of inhibition have been determined for the interaction of human leukocyte elastase (HLE) with two series of peptide trifluoromethyl ketones (TFMKs): X-Val-CF3,X-Pro-Val-CF3,X-Val-Pro-Val-CF3, and X-Lys(Z)-Val-Pro-Val-CF3, where X is MeOSuc or Z. These compounds are "slow-binding" inhibitors of HLE and, thus, allow the determination of Ki, the dissociation constant for the stable complex of inhibitor and enzyme, as well as kon and koff, the rate constants for formation and decomposition of this complex. Maximal potency is reached with Z-Lys(Z)-Val-Pro-Val-CF3, which displays a Ki less than 0.1 nM. Upon binding to HLE, these compounds undergo addition by the hydroxyl of the active site serine to form a hemiketal. The evidence supporting a hemiketal intermediate includes Ki values of 1.6 and 80,000 nM for Z-Val-Pro-Val-CF3 and its alcohol analogue, linear free energy correlations between inhibitory potency and catalytic efficiency for structurally related TFMKs and substrates, and the pH dependence of kon for the inhibition of HLE by Z-Val-Pro-Val-CF3, which is sigmoidal and displays a pKa of 6.9. Hemiketal formation is probably not rate limiting, however. Kinetic solvent isotope effects of unity suggest that kon cannot be rate limited by a reaction step, like hemiketal formation, that is subject to protolytic catalysis. A general mechanism that is consistent with these results is one in which formation of the hemiketal is rapid and is followed or preceded by a slow step that rate limits kon.(ABSTRACT TRUNCATED AT 250 WORDS)

Humans↗