Asymptomatic bacteriuria in the Port Harcourt metropolis of Nigeria

The Port Harcourt metropolis of Nigeria was screened to establish the prevalence of asymptomatic bacteriuria (ABU) over a 3 year period. An occurrence rate of 15% was detected. The females presented a higher incidence rate (9%) than the males (6%). Previous history of urinary tract infection (UTI) was seen to be contributory to ABU; so also was sexual activity. Of the isolates obtained, Escherichia coli was found to be predominant (45%). An isolation rate of 3.7% was realised for Staphylococcus epidermidis. This emphasizes its role in UTI. The advantages of screening for ABU was examined and it is suggested that individuals should be screened for ABU at least twice a year.     

Cancer in relatives of leukemic patients with chromosomal rearrangements at rare (heritable) fragile-site locations in their malignant cells.

The cancer occurrence in relatives (N = 407) of 40 case probands (who had leukemia and rearrangements at the same chromosomal location as at least one of 23 recognized rare [heritable] autosomal fragile sites [Sutherland and Mattei 1987]) was compared both to cancer occurrence in relatives (N = 390) of 40 control probands (who had leukemia or other hematologic illness but no recognized chromosomal rearrangements) and to cancer incidence in the general population of the United States. Fragile-site carrier status was not determined in case or control probands. No significant excess of cancer in case relatives, compared with either control relatives or to general (SEER) population expectancies, was found. Furthermore, there was neither evidence of cancer at younger ages, when cases were compared with control relatives, nor an excess of cancer at multiple sites. Male relatives of cases did, however, show a small excess of cancer, especially in older age groups. There was a slight, but not statistically significant, excess of lung cancer in case relatives, with this deviation occurring almost exclusively in relatives of probands having rearrangements at 11q23 and having lymphoid leukemia. It is possible that heritable tendency to chromosomal rearrangement--and thus to cancer--is expressed in such a small proportion of family members that cancer excess in these families could not be detected with the numbers of relatives analyzed in this study, although there was no significant evidence for a hereditary predisposition to cancer in the families of probands with leukemia and with chromosomal rearrangements at the same apparent chromosomal location as rare fragile sites.     

Virulence factors from Aeromonas species

Isolates (116) of Aeromonas were obtained from various sources and subjected to tests to establish their virulence factors. A high number of the isolates (69.8%) were found to be enterotoxigenic. The isolates from snails had more enterotoxigenic strains (73.3%), while those from cattle faeces had the lowest (33.3%). Haemolysin production was found to be high (60.3%) amongst the isolates, and human isolates gave the highest number of haemolysin producing strains (70.6%), while the least number (33.3%) was obtained from cattle strains. About 50% of the strains produced both enterotoxin and haemolysin. The enzyme profile of the isolates included amylase, lecithinase, lipase and protease. There was no definite pattern in the elaboration of these enzymes and the production of haemolysin and enterotoxin, thus inferring that the production of these factors is not specific to the source. Two isolates were seen to produce none of these enzymes, and one was positive for enterotoxin and haemolysin production, leaving only one isolate which yielded none of these factors. The work adds more support to the pathogenicity of Aeromonas species, and indicates the existence of non-pathogenic strains.     

Effects of low-chloride solutions on action potentials of sheep cadiac purkinje fibers

The rapid repolarization during phase 1 of the action potential of sheep cardiac purkinje fibers has been attributed to a time- and voltage-dependent chloride current. In part, this conclusion was based on experiments that showed a substantial slowing of phase 1 when larger, presumably impermeant, anions were substituted for chloride in tyrode’s solution. We have re- examined the electrical effects of low-chloride solutions. We recorded action potentials of sheep cardiac purkinje fibers in normal tyrode’s solution and in low-chloride solutions made by substituting sodium propionate, acetylglycinate, methylsulfate, or methanesulfonate for the NaCl of Tyrode’s solution. Total calcium was adjusted to keep calcium ion activity of test solutions equal to that of control solutions. Propionate gave qualitatively variable results in preliminary experiments; it was not tested further. Low-chloride solutions made with the other anions gave much more consistent results: phase 1 and the notch that often occurs between phases 1 and 2 were usually unaffected, and the action potential duration usually increased. The only apparent change in the resting potential was a transient 3-6 mV depolarization when low-chloride solution was first admitted to the chamber, and a symmetrical transient hyperpolarization when chloride was returned to normal. If a time- and voltage-dependent chloride current exists in sheep cardiac purkinje fibers, our results suggest that it plays little role in generating phase 1 of the action potential.     

Plasminogen activator and collagenase production by cultured capillary endothelial cells

Cultured bovine capillary endothelial (BCE) cells produce low levels of collagenolytic activity and significant amounts of the serine protease plasminogen activator (PA). When grown in the presence of nanomolar quantities of the tumor promoter 12-O-tetradecanoyl phorbol-13-acetate (TPA), BCE cells produced 5-15 times more collagenolytic activity and 2-10 times more PA than untreated cells. The enhanced production of these enzymes was dependent on the dose of TPA used, with maximal response at 10(-7) to 10(-8) M. Phorbol didecanoate (PDD), an analog of TPA which is an active tumor promoter, also increased protease production. 4-O-methyl-TPA and 4α-PDD, two analogs of TPA which are inactive as tumor promoters, had no effect on protease production. Increased PA and collagenase activities were detected within 7.5 and 19 h, respectively, after the addition of TPA. The TPA-stimulated BCE cells synthesized a urokinase-type PA and a typical vertebrate collagenase. BCE cells were compared with bovine aortic endothelial (BAE) cells and bovine embryonic skin (BES) fibroblasts with respect to their production of protease in response to TPA. Under normal growth conditions, low levels of collagenolyic activity were detected in the culture fluids from BCE, BAE, and BES cells. BCE cells produced 5-13 times the basal levels of collagenolytic activity in response to TPA, whereas BAE cells and BES fibroblasts showed a minimal response to TPA. Both BCE and BAE cells exhibited relatively high basal levels of PA, the production of which was stimulated approximately threefold by the addition of TPA. The observation that BCE cells and not BAE cells produced high levels of both PA and collagenase activities in response to TPA demonstrates a significant difference between these two types of endothelial cells and suggests that the enhanced detectable activities are a property unique to bovine capillary and microvessel and endothelial cells.     

Dissociation of intracellular lysosomal rupture from the cell death caused by silica

The relationship between intracellular lysosomal rupture and cell death caused by silica was studied in P388d(1) macrophages. After 3 h of exposure to 150 μg silica in medium containing 1.8 mM Ca(2+), 60 percent of the cells were unable to exclude trypan blue. In the absence of extracellular Ca(2+), however, all of the cells remained viable. Phagocytosis of silica particles occurred to the same extent in the presence or absence of Ca(2+). The percentage of P388D(1) cells killed by silica depended on the dose and the concentration of Ca(2+) in the medium. Intracellular lyosomal rupture after exposure to silica was measured by acridine orange fluorescence or histochemical assay of horseradish peroxidase. With either assay, 60 percent of the cells exposed to 150 μg silica for 3 h in the presence of Ca(2+) showed intracellular lysosomal rupture, was not associated with measureable degradation of total DNA, RNA, protein, or phospholipids or accelerated turnover of exogenous horseradish peroxidase. Pretreatment with promethazine (20 μg/ml) protected 80 percent of P388D(1) macrophages against silica toxicity although lysosomal rupture occurred in 60-70 percent of the cells. Intracellular lysosomal rupture was prevented in 80 percent of the cells by pretreatment with indomethacin (5 x 10(-5)M), yet 40-50 percent of the cells died after 3 h of exposure to 150 μg silica in 1.8 mM extracellular Ca(2+). The calcium ionophore A23187 also caused intracellular lysosomal rupture in 90-98 percent of the cells treated for 1 h in either the presence or absence of extracellular Ca(2+). With the addition of 1.8 mM Ca(2+), 80 percent of the cells was killed after 3 h, whereas all of the cells remained viable in the absence of Ca(2+). These experiments suggest that intracellular lysosomal rupture is not causally related to the cell death cause by silica or {"type":"entrez-nucleotide","attrs":{"text":"A23187","term_id":"833253","term_text":"A23187"}}A23187. Cell death is dependent on extracellular Ca(2+) and may be mediated by an influx of these ions across the plasma membrane permeability barrier damaged directly by exposure to these toxins.