Regulation of murine T cell proliferation by B cell stimulatory factor-1

The proliferation of mitogen-activated primary T cells, antigen-activated memory T cells from mixed leukocyte culture, and antigen-dependent alloreactive T cell clones in response to purified murine recombinant B cell stimulatory factor-1 (also known as interleukin 4) was examined. We found that B cell stimulatory factor-1 (BSF-1) stimulated optimal proliferation of these T cells only after their recent activation by antigen or mitogen. Analysis of cell surface BSF-1 receptor expression indicated that although T cell activation is accompanied by a small increase in BSF-1 receptor expression, the cells also express BSF-1 receptors prior to activation at a time when they do not proliferate in response to BSF-1. BSF-1 was as effective a stimulus as interleukin 2 for inducing proliferation of the Lyt-2+ subpopulation of concanavalin A-activated murine spleen cells and an alloreactive cytolytic T cell clone. However, the L3T4+ subpopulation of concanavalin A-activated spleen and an alloreactive helper T cell clone were less responsive to BSF-1 than to interleukin 2. Taken together, the data indicate an important role for BSF-1 in the regulation of normal T cell proliferation.     

The increase of oxygen consumption after a flash of light is tightly coupled to sodium pumping in the lateral ocellus of barnacle

In the lateral ocellus of the barnacle, we have tested the hypothesis that the transient increase of oxygen consumption (delta QO2) induced by light results from an increase in the rate of Na+ pumping. With a Na(+)-sensitive microelectrode, we measured the intracellular concentration of Na+ (Nai) in the photoreceptor cells. Nai was 17.6 +/- 1.2 mM (SE; n = 18) in darkness and it increased transiently by 10-20 mM after an 80-ms flash of intense light. The increase of Nai recovered in about the same time as the delta QO2, and the Na+/O2 ratio was 19.2 +/- 3.8 (SE; n = 6). Removing Na+ from the bath caused the delta QO2 to decrease by 79 +/- 3% (SE; n = 5). Exposure to 25 microM ouabain inhibited Na+ pumping and abolished the delta QO2. Removal of K+ from the bathing solution inhibited Na+ pumping in darkness, but mostly shortened the duration of the delta QO2; with a K(+)-sensitive microelectrode, we measured pericellular [K+] and found that it increased after the flash for about the same time as the delta QO2. Increasing Na+ pumping in darkness by reintroducing K+ in the bath or by injecting Na+ into one of the photoreceptor cells induced a delta QO2. Finally, intracellular injection of adenosine diphosphate and inorganic phosphate (ADP + Pi), the metabolic products of ATP splitting by the Na+ pump, also induced a delta QO2 in darkness. We conclude that all the results obtained are consistent with the formulated hypothesis.     

Occurrence of airborne bacteria and pathogen indicators during land application of sewage sludge.

Glass impingers (AGI-30) were used at a commercial sludge application site to determine the levels of airborne bacteria and pathogen indicators. Even though heterotrophic bacteria averaged 10(5) CFU/m3, none of the sites showed the presence of Salmonella spp. or indicators such as fecal coliforms or coliphages. Indicators such as H2S producers and pathogenic clostridia were present in locations having significant physical agitation of the sludge material. PCR-based ribotyping using the 16S-23S interspacer region is a promising method to identify the genetic relatedness and origins of airborne clostridia.     

The Steel factor.

Steel factor (SLF) is a recently identified growth factor which is the gene product of the murine Steel locus and a ligand for the c-kit tyrosine kinase receptor, the product of the dominant white spotting locus (W). Defects at these genetic loci result in aberrant melanocyte, germ cell, and hematopoietic development. Both the receptor (c-kit) and the ligand (SLF) have been shown to undergo tissue-specific mRNA splicing to produce distinct isoforms which have unique biological functions. As predicted by the phenotype of these mutations, SLF influences the growth and differentiation of melanocytes, primordial germ cells, and a broad spectrum of cell types in the hematopoietic progenitor and stem cell hierarchy. SLF has also been shown to have effects on hematopoietic lineages not predicted by defects seen in the Steel mouse.     

Calf rennet lysozyme.

A glycosidase displaying endo-N-acetylmuramoylhydrolase specificity (EC 3.2.1.17) was isolated from calf rennet. This lysozyme was also present in abomasal secretions from calf and adult cattle. Multiple molecular forms revealed by electrofocusing might be artefacts. The main enzyme form had Mr approx. 15 000, pH optimum 5.0, pI7.5, and a remarkable conformation stability. Competitive inhibition was observed with both N-acetylglucosamine and N-acetylmuramic acid, with apparent Ki values of 29 mM and 2.4 mM respectively. The isolated enzyme also displayed significant chitinase activity.     

Fingerprinting of Mixed Bacterial Strains and BIOLOG Gram-Negative (GN) Substrate Communities by Enterobacterial Repetitive Intergenic Consensus Sequence-PCR (ERIC-PCR)

PCR-based genomic fingerprinting by use of enterobacterial repetitive intergenic consensus primers (ERIC-PCR) was evaluated for its use in fingerprinting DNA of mixed Gram-negative bacterial strains and BIOLOG Gram-negative (GN) microplate substrate communities. ERIC-PCR fingerprints of six different pure bacterial strains and a combined mixture of the strains were compared with fingerprints obtained by two more established methods: amplified ribosomal DNA restriction analysis (ARDRA) and random amplified polymorphic DNA analysis (RAPD-PCR). The ERIC-PCR fingerprint of the mixed strains was highly reproducible and was more species-specific and representative of the individual strain fingerprints than the ARDRA and RAPD-PCR fingerprints, respectively. ERIC-PCR fingerprinting of model and rhizosphere BIOLOG GN substrate communities also provided clearly distinguishable fingerprints. Results of this study suggest that ERIC-PCR represents a rapid and highly discriminating method for fingerprinting DNA of mixed Gram-negative bacterial strains and BIOLOG GN substrate communities. Received: 11 September 1998 / Accepted: 29 October 1998     

A Prospective Epidemiological Study of Acute Mountain Sickness in Nepalese Pilgrims Ascending to High Altitude (4380 m)

Background

Each year, thousands of pilgrims travel to the Janai Purnima festival in Gosainkunda, Nepal (4380 m), ascending rapidly and often without the aid of pharmaceutical prophylaxis.

Methods

During the 2012 Janai Purnima festival, 538 subjects were recruited in Dhunche (1950 m) before ascending to Gosainkunda. Through interviews, subjects provided demographic information, ratings of AMS symptoms (Lake Louise Scores; LLS), ascent profiles, and strategies for prophylaxis.

Results

In the 491 subjects (91% follow-up rate) who were assessed upon arrival at Gosainkunda, the incidence of AMS was 34.0%. AMS was more common in females than in males (RR = 1.57; 95% CI = 1.23, 2.00), and the AMS incidence was greater in subjects >35 years compared to subjects ≤35 years (RR = 1.63; 95% CI = 1.36, 1.95). There was a greater incidence of AMS in subjects who chose to use garlic as a prophylactic compared to those who did not (RR = 1.69; 95% CI = 1.26, 2.28). Although the LLS of brothers had a moderate correlation (intraclass correlation = 0.40, p = 0.023), sibling AMS status was a weak predictor of AMS.

Conclusions

The incidence of AMS upon reaching 4380 m was 34% in a large population of Nepalese pilgrims. Sex, age, and ascent rate were significant factors in the development of AMS, and traditional Nepalese remedies were ineffective in the prevention of AMS.     

Frequent Occurrence of Mixed Enterocytozoon bieneusi Infections in Humans

Enterocytozoon bieneusi (phylum Microsporidia) is a human pathogen with a broad host range. Following the sequencing of 3.8 Mb of the estimated 6-Mb E. bieneusi genome, simple sequence repeats (micro- and minisatellites) were identified. Sequencing of four such repeats from various human and animal E. bieneusi isolates identified extensive sequence polymorphism and enabled the development of a multilocus genotyping method to study the epidemiology of this pathogen. We genotyped E. bieneusi DNA extracted from 197 fecal samples originating from children with diarrhea who were residing in Kampala, Uganda. Three newly identified microsatellite markers and the internal transcribed spacer were PCR amplified, and multiple cloned amplicons for each marker were sequenced from each individual. Most microsatellite sequences were unique to the Ugandan population. Significantly, polymorphism not only was present among isolates but was also found within isolates. This observation suggests that infections with heterogeneous E. bieneusi populations are common in this region. However, the data do not exclude that some of the polymorphism originates from divergent paralogs within the genome. The frequent occurrence of multiple sequences within an isolate precluded the identification of multilocus genotypes. This observation raises the possibility that in a region in which the prevalence of E. bieneusi is high, sequencing of uncloned PCR products may not be adequate for multilocus genotyping.