Copper resistance determinants in bacteria.

Copper is an essential trace element that is utilized in a number of oxygenases and electron transport proteins, but it is also a highly toxic heavy metal, against which all organisms must protect themselves. Known bacterial determinants of copper resistance are plasmid-encoded. The mechanisms which confer resistance must be integrated with the normal metabolism of copper. Different bacteria have adopted diverse strategies for copper resistance, and this review outlines what is known about bacterial copper resistance mechanisms and their genetic regulation.     

Fertility after bilateral cryptorchidism. Evaluation by paternity, hormone, and semen data.

PURPOSE: Evaluation of the fertility of a cohort of formerly bilaterally cryptorchid men in comparison with a group of formerly unilaterally cryptorchid men, and a group of control men. MATERIALS AND METHODS: Using a detailed questionnaire concerning paternity and factors related to paternity, a cohort of formerly bilateral cryptorchid men were studied and compared with men who had undergone orchiopexy for unilateral cryptorchidism, and a group of control men. All study subjects had had surgery at the Children's Hospital of Pittsburgh, Pittsburgh, Pa., between 1955 and 1975. A subset of the full cohort underwent clinical evaluation that included a physical examination, serum hormonal determination and semen analyses. RESULTS: Paternity rates are significantly lower among the formerly bilaterally cryptorchid men who have attempted to father a child (65.3%) as compared to the formerly unilaterally cryptorchid (89.7%; p < 0.001) and control men (93.2%; p < 0.001). Differences in the ability to father children are also apparent when semen and hormone levels are compared between the three groups. The bilateral group has significantly lower sperm density and inhibin B levels, and higher FSH and LH levels, than the unilateral and control groups. CONCLUSIONS: Men born with bilateral cryptorchidism have severely compromised fertility in adulthood. This reduction in fertility is clearly shown in comparisons of both paternity rates, and in semen and hormone analyses, between the formerly bilateral, formerly unilateral, and control groups.     

Serologic survey for evidence of exposure to vesicular stomatitis virus, pseudorabies virus, brucellosis and leptospirosis in collared peccaries from Arizona

Two hundred eighteen usable serum samples were collected from hunter-killed collared peccaries (Tayassu tajacu) during March 1986, in three areas of Arizona. Evaluations for antibodies against vesicular stomatitis virus (VSV) New Jersey (NJ) type, VSV Indiana type, pseudorabies virus, brucellosis, and leptospirosis revealed positive test results in 8%, 0%, less than 1%, 0%, and 23% of the sera, respectively. Exposure of peccaries to VSV (NJ) was widespread, but variation in the prevalence of seropositive peccaries was not found between the three areas sampled. The exposure of peccaries to VSV (NJ) probably was related to the recent epizootics in livestock in the vicinity. Exposure to Leptospira interrogans serovars also was widespread, and geographic variation in the prevalence of peccaries with antibodies against L. interrogans was found.     

Gastroduodenal ulceration following active immunization with prostaglandin E2 in dogs. Role of gastric acid secretion

In this study we present evidence to suggest that gastroduodenal mucosal defects may occur in gastric fistula dogs actively immunized with PGE2-thyroglobulin conjugate. One of four PGE2-immunized dogs developed a chronic pyloroduodenal ulcer with penetration into the pancreas and the other three had endoscopic evidence of gastric and/or duodenal erosions. In contrast, no gastroduodenal mucosal defects were seen in control dogs immunized with thyroglobulin alone. Occurrence of gastroduodenal ulcers or erosions was temporally related to formation of specific antibody to PGE2 suggesting that PGE2 antibody may be responsible for lesion formation. An increase in gastric acid secretion was not observed in PGE2-immunized dogs. Thus, it is likely that mucosal defects occur as a result of an impairment of PGE2-mediated mucosal defense mechanisms. Since gastroduodenal lesions can be visualized by endoscopy, the dog may prove to be useful in studying the role of endogenous PG in ulcer diseases.     

Effects of PGE1 or PGE2 and/or acetazolamide on expulsion of Nippostrongylus brasiliensis from rats

PGE1 and PGE2 have been reported to enhance natural expulsion of Nippostrongylus brasiliensis, a nematode parasite, from the intestine of the rat. Mucus production may also be a key element of worm rejection. Our study attempts to determine if 1) PGE1 or PGE2 alter the normal course of infection with N. brasiliensis in rats, 2) a known mucous enhancing drug, acetazolamide, can augment the rate of worm expulsion, and 3) combinations of prostaglandins and acetazolamide affect N. brasiliensis in the rat. Rats were inoculated with approximately 1,000 infective larvae of N. brasiliensis. Animals were administered, intraduodenally, one of the following: 0.2 ml 0.9% NaCl; 0.2 ml 100% ethanol; 250 micrograms PGE1/0.2 ml 100% ethanol; 250 micrograms PGE2/0.2 ml 100% ethanol; 250 micrograms acetazolamide/0.2 ml 100% ethanol; 250 micrograms PGE1 or PGE2 + 250 micrograms acetazolamide/0.2 ml 100% ethanol. These solutions were given in a single bolus on day 6 postinoculation (PI) or twice daily on days 6-9 PI. Following these treatments the number of parasite ova per gram feces per day for days 6-10 PI and numbers of worms present at necropsy on day 10 PI were determined. Treatment with prostaglandins or acetazolamide or both failed to adversely affect egg deposition by adult female worms or the number of worms in the small intestine. These results do not support the involvement of prostaglandins in the expulsion of N. brasiliensis from the host intestine.     

Examination and characterization of distribution system biofilms

Investigations concerning the role of distribution system biofilms on water quality were conducted at a drinking water utility in New Jersey. The utility experienced long-term bacteriological problems in the distribution system, while treatment plant effluents were uniformly negative for coliform bacteria. Results of a monitoring program showed increased coliform levels as the water moved from the treatment plant through the distribution system. Increased coliform densities could not be accounted for by growth of the cells in the water column alone. Identification of coliform bacteria showed that species diversity increased as water flowed through the study area. All materials in the distribution system had high densities of heterotrophic plate count bacteria, while high levels of coliforms were detected only in iron tubercles. Coliform bacteria with the same biochemical profile were found both in distribution system biofilms and in the water column. Assimilable organic carbon determinations showed that carbon levels declined as water flowed through the study area. Maintenance of a 1.0-mg/liter free chlorine residual was insufficient to control coliform occurrences. Flushing and pigging the study area was not an effective control for coliform occurrences in that section. Because coliform bacteria growing in distribution system biofilms may mask the presence of indicator organisms resulting from a true breakdown of treatment barriers, the report recommends that efforts continue to find methods to control growth of coliform bacteria in pipeline biofilms.