Malcolm C. Modrzakowski

Meconial peritrophic membranes and the fate of midgut bacteria during mosquito (Diptera: Culicidae) metamorphosis.

Abstract The location of midgut bacteria relative to meconial peritrophic membranes (MPMs) and changes in bacterial numbers during midgut metamorphosis were studied in Anopheles punctipennis (Say), Culex pipiens (L.), and Aedes aegypti (L.) pupae and newly emerged adults. After adult emergence in Aedes, Anopheles, and most Culex, there were few to no bacteria in the midgut. In most newly emerged adult mosquitoes, few bacteria were found in either the lumen or within the MPMs/meconia. In a few Culex specimens, high numbers of bacteria were found in the MPMs/meconia and low numbers in the lumen. In all three species bacterial counts were high in fourth instars, decreased after final larval defecation, increased in young pupae, and increased further in old pupae. A very effective gut sterilization mechanism is operating during mosquito metamorphosis and adult emergence. This mechanism appears to involve the sequestration of remaining larval gut bacteria within the confines of the meconium and one or two MPMs and the possible bactericidal effect of the exuvial (molting) fluid, which is ingested during the process of adult emergence.

A comparative analysis of human IgM rheumatoid factor degradation by purified elastase and total granule extracts from human polymorphonuclear leukocytes

A modified digestion system using radiolabeled IgM rheumatoid factors (RF) and unlabeled IgG was used to examine IgM RF digestion by human polymorphonuclear leukocyte (PMN) elastase. Upon molecular sieve chromatography, the radioactive fragments coelute with fragments produced by elastase digestion of an IgM protein having no RF activity. The fragments represent an Fab2-like fragment, an Fab-like fragment, and small peptides. Utilizing this same system, digests were performed at both acid and neutral pH to compare the proteolytic action of purified elastase on IgM RF (Ove) to the action of the total granule extract (TGE) from human PMN. At pH 4.5, purified elastase exhibits low-level protease activity, producing a slightly degraded IgM fragment with a molecular weight of about 800,000 daltons. In contrast, TGE at pH 4.5 completely degrades IgM RF to small peptides. At pH 7.5, the fragments produced by TGE digestion of IgM (Ove) coelute with fragments produced by elastase digestion under the same conditions. Thus elastase appears to be the major granule protease active in IgM RF degradation at the pH characterizing the inflammatory site.

Isolation of cationic peptides from rat polymorphonuclear leukocyte granule contents using fast protein liquid chromatography.

Separation of extracted rat polymorphonuclear leukocyte (PMN) granule contents using fast protein liquid chromatography yielded four major protein fractions. These fractions consisted of myeloperoxidase (peak A), neutral protease (peak B), lysozyme (peak C), and low molecular weight, cationic peptides (peak D). This study represents the first noted purification of the cationic peptides of rat PMN granules.

Women in Osteopathic and Allopathic Medical Schools: An Analysis of Applicants, Matriculants, Enrollment, and Chief Academic Officers

In the 1993-1994 academic year, female enrollment was 34.7% in osteopathic medical schools and 40.2% in allopathic medical schools. To assess progress in female enrollment since that time, the authors examined admission data in the ensuing years, including female applicants, matriculants, and first-year students in osteopathic and allopathic medical schools, as well as female chief academic officers at these institutions. In the 2004-2005 academic year, 50.3% of first-year students in osteopathic medical schools were women; however, by the 2013-2014 academic year, that figure dropped to 44.2%. The percentage rose slightly by the 2016-2017 academic year to 45.9%. Additionally, for the 2016-2017 academic year, allopathic medical schools had a significantly higher proportion of female matriculants than did osteopathic medical schools (49.8% vs 45.9%, respectively; P<.001).