RAPD typing of clinical isolates of Staphylococcus haemolyticus

The randomly amplified polymorphic DNA (RAPD) assay was used to generate DNA fingerprints from clinical isolates of Staphylococcus haemolyticus isolated from patients treated with continuous ambulatory peritoneal dialysis and previously subjected to a combination of typing methods. The RAPD profiles generated with one of six randomly designed 10-mer primers allowed visual discrimination of strains. Good correlation with the original typing scheme was achieved but RAPD typing allowed discrimination of strains previously indistinguishable.     

Neurogenic peptides and the cardiomyopathy of magnesium-deficiency: Effects of substance P-receptor inhibition

Dietary deficiency of magnesium (Mg) in rodents results in cardiomyopathic lesion formation. In our rat model, these lesions develop after 3 weeks on the Mg-deficient diet; significant elevation of several cytokines, IL-1, IL-6 and TNF also occurs. In probing the mechanisms of lesion formation, we obtained data supporting the participation of free radicals (Freedman AMet al.: Bioch Biophys Res Commun 1990; 170: 1102). Recently, we identified an early elevation of circulating substance P and proposed a role of neurogenic peptides during Mg-deficiency (Weglicki WB, Phillips TM: Am J Phys 1992; 262: R734). The present study was designed to evaluate the contribution of neurogenic peptides to the pathogenesis of Mg-deficiency. In the blood, substance-P and calcitonin gene related peptide (CGRP) are elevated during the first week on the diet. During the second week, circulating histamine, PGE₂ and TBAR-materials were elevated and red cell glutathione was reduced, all prior to the elevation of the inflammatory cytokines during the third week. When the rats were treated with the substance P-receptor blocker [CP-96,345], the levels of substance P and CGRP remained elevated; however, increases in histamine, PGE₂, TBAR-materials, and the decrease in red cell glutathione were inhibited; also, the development of cardiac lesions was inhibited significantly. These data support a central role for neurogenic peptides, especially substance P, in the development of cardiomyopathic lesions during Mg-deficiency.     

GEOGRAPHIC DISTRIBUTION OF MITOCHONDRIAL DNA VARIANTS AND THE HISTORICAL BIOGEOGRAPHY OF THE SPOTTED SALAMANDER,AMBYSTOMA MACULATUM

I analyzed geographic partitioning of mitochondrial DNA (mtDNA) restriction-site variants in the spotted salamander, Ambystoma maculatum. Two highly divergent and geographically separate genetic lineages were identified that differed by a minimum of 19 restriction sites (6% sequence divergence). One of the lineages has a disjunct distribution with very closely related haplotypes occurring in Missouri, Arkansas, North Carolina, and Virginia. The other lineage is found in Michigan, Illinois, and Alabama. The geographic separation of highly divergent mtDNA haplotypes, a pattern that was predicted based on the sedentary nature of these salamanders, is evidence for long-term barriers to gene flow. In contrast, the large-scale disjunction of very similar haplotypes suggests recent, long-distance gene flow and does not match the phylogeographic expectation for a small terrestrial vertebrate. I explain this potential contradiction in the level of importance assigned to gene flow by a scenario in which historical barriers to gene flow account for the two divergent mtDNA assemblages, but stochastic sorting of ancestral polymorphism is responsible for the large-scale geographic disjunction. Ten of 16 populations collected in the Ozark Highlands were fixed for the same haplotype. I attribute this lack of detectable variation to recent colonization of this area, a hypothesis that is supported by paleoecological data and demonstrates the potential benefits of combining data from paleobotany, geology, and other disciplines to reconstruct the historical biogeography of a species.     

Synthesis of intraspecific somatic hybrids of Solanum tuberosum: assessments of morphological, biochemical and nematode (Globodera pallida) resistance characteristics

In an attempt to produce novel agronomic traits, a number ofintraspecific somatic hybrid plants have been produced followingleaf mesophyll protoplast fusion between S. tuberosum dihaploidclones PDH 40 (possessing good tuber shape and yield) and PDH417 (possessing resistance to potato cyst nematode, G. pallida).PDH 417 protoplast-derived calli failed to regenerate plantsusing the described culture conditions preventing this parentaltype amongst the mass of regenerated fusion products. Initially,somatic hybrid plants were selected based on differential pigmentationin tuber sprouts and where possible on petal colour. Differentialmobility of patatin bands in electrophoresed tuber extractsfurther confinned hybridity. The intraspecific somatic hybridsalso showed different levels of resistance to G. pallida pathotypesPa2 and Pa3 in the somatic hybrid plants examined. Key words: Somatic hybridization, dihaploids, patatin, nematode resistance, Solanum tuberosum, potato     

B1 and B2 Bradykinin Receptors Encoded by Distinct mRNAs

Abstract: Bradykinin receptors have been subdivided into at least two major pharmacological subtypes, B₁ and B₂. The cDNAs encoding functional B₂ receptors have recently been cloned, but no molecular information exists at present on the B₁ receptor. In this article, we describe experiments examining the possible relationship between the mRNAs encoding the B₁ and B₂ types of receptor. We showed previously that the Human fibroblast cell line W138 expresses both B₁ and B₂ receptors. In this report, we describe oocyte expression experiments showing that the B₁ receptor in W138 human fibroblast cells is encoded by a distinct mRNA ∼2 kb shorter than that encoding the B₂ receptor. We have used an antisense approach in conjunction with the oocyte expression system to demonstrate that the two messages differ in sequence at several locations throughout the length of the B₂ sequence. Taken together with the mixed pharmacology exhibited in some expression systems by the cloned mouse receptor, the data indicate that B₁-type pharmacology may arise from two independent molecular mechanisms.     

HIV disease progression in 854 women and men infected through injecting drug use and heterosexual sex and followed for up to nine years from seroconversion. Italian Seroconversion Study.

OBJECTIVE--To compare the progression of HIV-1 infection in men and women followed up for up to nine years after an accurately estimated date of seroconversion. DESIGN--Prospective observational study. SETTING--16 HIV outpatient clinics across Italy. SUBJECTS--321 women and 533 men infected with HIV through injecting drug use or heterosexual sex and with accurately estimated dates of seroconversion. MAIN OUTCOME MEASURES--Progression to severe CD4 lymphocytopenia (CD4 lymphocyte count < 200 x 10(6)/l), development of AIDS defining diseases, and death from AIDS. RESULTS--Thirty two women and 67 men developed AIDS at Kaplan-Meier progression rates of 25% (95% confidence interval 13.8% to 35.5%) and 23% (15.6% to 30.4%), respectively, 7 years after seroconversion. In a Cox proportional hazards model the relative hazard was 0.93 (that is, a slightly lower hazard in women) before and 1.10 (0.70 to 1.72) after adjusting for age, HIV exposure group, and year of seroconversion. When CD4 lymphocytopenia and death from AIDS were used as end points the results were similar, with adjusted relative hazards of 0.95 (0.63 to 1.42) and 0.72 (0.48 to 1.79) respectively. In both women and men the risk of developing AIDS before the CD4 lymphocyte count had declined below 200 x 10(6)/l was small (3% in women, 6% in men). The estimated median count at which AIDS developed in women (34 x 10(6)/l; 10 x 10(6) to 44 x 10(6)) was similar to that for men (44 x 10(6)/l; 22 x 10(6) to 60 x 10(6)). CONCLUSION--There seems to be little evidence for appreciable differences in the natural course of HIV infection between men and women followed up from the time of seroconversion.