Effects of a Single Histoplasmin Skin Test on the Serological Diagnosis of Histoplasmosis

Numerous reports have indicated that a single histoplasmin skin test may stimulate humoral antibodies to Histoplasma capsulatum antigens in histoplasmin-hypersensitive individuals. Although these investigations concur that antibody elevations are evoked, they vary in the reported degree of incidence and response induced, and they cast doubt on the interpretation of serological tests in the diagnosis of histoplasmosis. Histoplasmin-hypersensitive subjects (114) were bled prior to administration of the skin test, 2 days later, at the time this test was read, and 15 and 30 days after testing. No significant antibody titers were observed at 2 days. At 15- and 30-day intervals, only 17 (15%) of the subjects demonstrated circulating antibodies. All 17 showed agar gel bands; 5 demonstrated no complement-fixation (CF) titers, 10 produced CF antibodies ranging from 1:8 to 1:16, and 2 demonstrated titers of 1:32. The data suggest that skin testing does not interfere significantly with antibody levels in sera drawn approximately 2 days after administration of antigen. However, since titers as high as 1:32 were obtained at later intervals, such reactions should be evaluated cautiously and only after consideration of clinical findings.     

Anhidrotic ectodermal dysplasia as autosomal recessive trait in an inbred kindred

Anhidrotic ectodermal dysplasia in an inbred kindred was observed in three sisters and three first cousins. This was interpreted as presumptive evidence for autosomal recessive inheritance and it is suggested that in addition to its known genes, anhidrotic ectodermal dysplasia occasionally may be caused by an autosomal recessive gene.This investigation was supported by Public Health Service Research Grant No. FR 00123, from GCRC-DRFR and by a Fellowship in Pediatric Teratology of the Children's Hospital Research Foundation, Cincinnati.     

Relationship between tektins and intermediate filament proteins: an immunological study

Affinity-purified antibodies raised against three flagellar tektins (tektin A, B, and C) from each of two sea urchin species (Lytechinus pictus and Strongylocentrotus purpuratus) were used to study the immunological relationship between tektins and intermediate filament proteins. By immunofluorescence microscopy, several antitektins revealed a staining of intermediate filament-like arrays in three vertebrate cell lines tested. Immunoelectron microscopy substantiated the cross reaction of antitektins with intermediate filaments. When the cells were treated with cytochalasin B, the arrangement of the filaments recognized by anti-(Lp)-tektin B was altered; the alteration observed is typical for keratin filaments. By immunoblot, it was found that anti-(Lp)-tektin B cross reacted with two isoforms or different proteins of approximately 54 kD with pIs of 6.1 and 6.2 in human carcinoma epithelia (HeLa) cells and with two isoforms or different proteins of approximately 55 kD with pIs of 6.1 and 6.3 in pig kidney epithelia (LLC-PK1) cells. Furthermore, when antitektin antibodies were affinity purified with the 54 kD HeLa keratin, these keratin-specific antibodies again restained the original tektins on immunoblots. From these observations, it can be concluded that tektins and keratins are to a certain extent immunologically related. To determine the degree of the immunological relationship, tektin filaments and purified intermediate filaments from HeLa cells were cleaved with alpha-chymotrypsin and examined by quantitative immunoblot analysis. On immunoblots of digested tektins from L. pictus, anti-(Lp)-tektin B recognized several cleavage products in the range of 20 kD to 46 kD. However, when immunoblots of digested intermediate filaments from HeLa cells were probed, the cross reaction of anti-(Lp)-tektin B with HeLa keratins was eliminated by more than 98% within 2 min, suggesting that tektins have epitopes in common with the end domains of certain keratins.     

The regulation of amyloid beta protein precursor secretion and its modulatory role in cell adhesion

The regulation and function of two forms of the amyloid beta protein precursor (ABPP) that are released into the growth-conditioned medium of the PC12 nerve cell line were examined. Nerve growth factor increases the release of the form of ABPP without the protease-inhibitor domain relative to the protein containing the protease inhibitor and increases the overall rate of ABPP secretion 2-fold. In contrast, fibroblast growth factor increases the rate of ABPP secretion approximately 7-fold. Both forms of the secreted ABPP molecule are, in turn, able to stimulate adhesion of PC12 cells to substrata to which they are adsorbed about 10-fold more efficiently on a molar basis than Iaminin.     

Activities of the pentose phosphate pathway and enzymes of proline metabolism in legume root nodules

Based on localization and high activities of pyrroline-5-carboxylate reductase and proline dehydrogenase activities in soybean nodules, we previously suggested two major roles for pyrroline-5-carboxylate reductase in addition to the production of the considerable quantity of proline needed for biosynthesis; namely, transfer of energy to the location of biological N₂ fixation, and production of NADP⁺ to drive the pentose phosphate pathway. The latter produces ribose-5-phosphate which can be used in de novo purine synthesis required for synthesis of ureides, the major form in which biologically fixed N₂ is transported from soybean root nodules to the plant shoot. In this paper, we report rapid induction (in soybean nodules) and exceptionally high activities (in nodules of eight species of N₂-fixing plants) of pentose phosphate pathway and pyrroline-5-carboxylate reductase. There was a marked increase in proline dehydrogenase activity during soybean (Glycine max) ontogeny. The magnitude of proline dehydrogenase activity in bacteroids of soybean nodules was sufficiently high during most of the time course to supply a significant fraction of the energy requirement for N₂ fixation. Proline dehydrogenase activity in bacteroids from nodules of other species was also high. These observations support the above hypothesis. However, comparison of pentose phosphate pathway and pyrroline-5-carboxylate reductase activities of ureide versus amide-exporting nodules offers no support. The hypothesis predicts that pyrroline-5-carboxylate and pentose phosphate pathway activities should be higher in ureide-exporting nodules than in amide-exporting nodules. This predicted distinction was not observed in the results of in vitro assays of these activities.     

Expression and regulation of a Bacteroides fragilis sucrose utilization system cloned in Escherichia coli

A Bacteroides fragilis strain isolated from human feces was the source of chromosomal DNA in the construction of plasmid pBS100. The cloned 6-kilobase insert of plasmid pBS100 conferred a sucrose positivity phenotype on transformed cells of Escherichia coli JA221. E. coli JA221(pBS100) cells were able to utilize sucrose as the sole source of carbon because of the presence of sucrase enzyme and sucrose uptake activities. Sucrase activity was inducible in B. fragilis but constitutive in E. coli JA221(pBS100) cells. In sucrose-minimal medium, both B. fragilis and E. coli JA221(pBS100) produced intracellular and extracellular sucrase activities throughout the growth cycle. Osmotic shock experiments performed on E. coli JA221(pBS100) indicated that up to 55% of the sucrase activity was localized in the periplasmic space, 30% was in the cytoplasm, and the remaining 15% was in the cell-free extracellular supernatant fluid. B. fragilis and E. coli JA221(pBS100) actively transported sucrose. Sucrose uptake was induced by sucrose in B. fragilis, whereas the uptake activity in E. coli JA221(pBS100) was constitutive. E. coli JA221(pBS100) appeared to transport sucrose by a phosphotransferase-independent system. B. fragilis transported sucrose only under strictly anaerobic conditions. No uptake activity was detected under aerobic conditions with or without addition of catalase.