Influence of the pseudophyllidean cestode Schistocephalus solidus on oocyte development in the threespine stickleback Gasterosteus aculeatus.

The objective of this study was to investigate the means by which Schistocephalus solidus might reduce annual fecundity in female threespine stickleback fish (Gasterosteus aculeatus) through processes of oocyte development. Histological examinations of specimens from one lake in Alaska in 2000 and 2001 were used to analyse the effects of S. solidus on recruitment of primary growth oocytes into vitellogenesis, atresia of vitellogenic oocytes, and the interspawning interval. The ratio of primary growth to late secondary growth (late vitellogenic) oocytes was significantly greater (P<0.01) among infected fish than uninfected ones in early-season samples from 2000 and 2001, revealing a decrease in recruitment of oocytes from primary growth into vitellogenic oocytes among infected females. The difference was marginally non-significant (P=0.087) in a mid-season sample from 2001 due to reductions in the entire pool of vitellogenic (early and late secondary growth) oocytes recruited prior to the spawning season in this determinate-fecundity species. Atresia among all vitellogenic oocytes was low and did not differ between infected and uninfected females. Histological estimations of the interspawning interval using post-ovulatory follicles showed no significant differences between infected and uninfected fish, suggesting that the number of spawnings in stickleback females each spawning season is unaffected by S. solidus infection. Thus, annual fecundity appears to be reduced only through recruitment of oocytes into vitellogenesis.

Interspawning interval of wild female three-spined stickleback Gasterosteus aculeatus in Alaska.

The interspawning interval, or spawning frequency, of wild three-spined stickleback, Gasterosteus aculeatus, was estimated using histological examination of postovulatory follicles (POF). Females in Alaskan lakes appeared to have as much as a 48 h delay between ovulation and ovoposition, yet the POF method could still be used to estimate the interspawning interval. In two Alaskan lakes the interspawning interval was estimated to range from 2.2 to 7.8 days among individual female G. aculeatus. These estimates were consistent with the range (2.5 to 5 days) of previous estimates among individual females from laboratory observations of spawning G. aculeatus, as well as anecdotal accounts of spawning intervals reported from wild populations in Canada (5-10 days). The interspawning interval of females increased during the course of the spawning season in Alaska, showing that the majority of female spawning activity occurred during the earliest portion of the approximate 6-week reproductive season. The increased interspawning interval appears to be related to a previously reported decrease in body condition in reproductive females during the breeding season. Thus, female G. aculeatus may be unable to sustain the initial rate of reproduction as energy stores that support the rapid growth of vitellogenic oocytes are depleted.

The relationship of maternal and child HIV infection to security of attachment among Ugandan infants.

This study was designed to examine the relationship of maternal and child human immunodeficiency virus (HIV) infection to the security of attachment of Ugandan infants. The attachment patterns of two groups of Ugandan mother-infant pairs: 35 HIV-positive mothers and their infants and 25 HIV-negative mothers and their infants were compared. We tested the hypothesis that infants of HIV-positive mothers would demonstrate less secure attachment as measured by the Waters Attachment Q-set than infants of HIV-negative mothers. No differences were found in the security of attachment of infants of HIV-positive versus HIV-negative mothers. Infants of HIV-positive mothers with Acquired Immunodeficiency Syndrome (AIDS) were less securely attached than infants of mothers without AIDS. These findings underscore the relationship of infant security of attachment to maternal HIV infection in the presence of AIDS-related symptoms but not to asymptomatic maternal HIV infection.

N-nitrosodiethylamine initiation of carcinogenesis in Japanese medaka (Oryzias latipes): hepatocellular proliferation, toxicity, and neoplastic lesions resulting from short term, low level exposure.

To investigate relationships among carcinogen exposure, cell proliferation, and carcinogenesis, 14-day post-hatch Japanese medaka (Oryzias latipes) were exposed to 0, 10, 25, 50, or 100 ppm N-nitrosodiethylamine (DEN) for 48 h under static renewal conditions. They were then held in clean water until sampling at 3 and 6 months. The frequencies of hepatic lesions and neoplasms were determined from hematoxylin/eosin-stained paraffin sections. A significant (p < 0.0001) concentration-related increase in hepatic vacuolated foci occurred in 3- and 6-month samples, with males having a significantly (p = 0.02) higher incidence than females. Concentration-related increases in degenerative lesions were documented for spongiosis hepatis at 3 months (p = 0.053) and hepatic vacuoles at 6 months (p = 0.005). There was a significant (p = 0.0001) concentration-related increase in macrophage aggregates at 6 months. Basophilic foci were significantly related (p < 0.0001) to DEN concentration at 3 months post-exposure and were unaffected by gender or age. At both 3 and 6 months, there were significant concentration-related increases in hepatocellular carcinoma (p < or = 0.02). Hepatocyte proliferation in 3-month whole specimens was quantified using an immunohistochemical assay for proliferating-cell nuclear antigen. Trend tests and a probit dose-response model showed a significantly positive correlation (p = 0.015) between proliferating hepatocytes and DEN concentrations. These results confirm that short-term exposure to low and moderate levels of DEN initiates concentration-dependent carcinogenic effects in medaka that are apparent at 3 months postexposure. DEN could be an effective initiator in an initiation/promotion assay for medaka using a 48-h exposure period, DEN concentrations < or = 10 ppm, and a 6-month sampling period.

Application of an analytic model to early readmission rates within the Department of Veterans Affairs.

OBJECTIVES: Adverse outcome rates are increasingly used as yardsticks for the quality of hospital care. However, the validity of many outcome studies has been undermined by the application of one outcome to all patients in large, diagnostically diverse populations, many of which lack evidence of a link between antecedent process of care and the rate of the outcome, the underlying assumption of the analysis. METHODS: To address this analytic problem, the authors developed a model that improves the ability to identify quality problems because it selects diseases for which there are processes of care known to affect the outcome of interest. Thus, for these diseases, the outcome is most likely to be causally related to the antecedent care. In this study of hospital readmissions, risk-adjusted models were created for 17 disease categories with strong links between process and outcome. Using these models, we identified outlier hospitals. RESULTS: The authors hypothesized that if the model improved on identifying hospitals with quality of care problems, then outlier status would not be random. That is, hospitals found to have extreme rates in one year would be more likely to have extreme rates in subsequent years, and hospitals with extreme rates in one condition would be more likely to have extreme rates in related disease categories. It was hypothesized further that the correlation of outlier status across time and across diseases would be stronger in the 17 disease categories selected by the model than in 10 comparison disease categories with weak links between process and outcome. CONCLUSIONS: The findings support all these hypotheses. Although the present study shows that the model selects disease-outcome pairs where hospital outlier status is not random, the causal factors leading to outlier status could include (1) systematic unmeasured patient variation, (2) practice pattern variation that, although stable with time, is not indicative of substandard care, or (3) true quality-of-care problems. Primary data collection must be done to determine which of these three factors is most causally related to hospital outlier status.

Alterations in oxidative activity and superoxide dismutase in Halobacterium halobium in response to aerobic respiratory inhibitors.

Aerobic incubation of Halobacterium halobium with low concentrations of cyanide or azide resulted in a twofold increase in activity of the Mn-containing superoxide dismutase (SOD). A similar effect was observed with antimycin A, albeit at a higher concentration. Oxygen consumption increased 100% at concentrations of cyanide, azide, and antimycin A that produced maximal SOD induction. Luminol chemiluminescence of H. halobium cells, indicative of oxidative activity, was elevated in the presence of concentrations of aerobic respiratory inhibitors that corresponded to maximal levels of SOD induction. In addition, oxidation of NADH by cell extracts was maximal at inhibitor concentrations that correlated with the peak induction of SOD. Proton fluxes for H. halobium cells also corresponded to concentration ranges of inhibitor resulting in greatest SOD levels, indicative of a potential uncoupling effect. A similar phenomenon was also observed with the uncoupler carbonyl cyanide m-chlorophenyl hydrazone. Growth was unaffected by inhibitors at the concentrations used for SOD induction. The results are interpreted as an induction of enhanced levels of SOD through a combination of increased electron flow and an increased oxidative environment.

Purification and characterization of a mesohalic catalase from the halophilic bacterium Halobacterium halobium.

When subjected to the stress of growth in a relatively low-salt environment (1.25 M NaCl), the halophilic bacterium Halobacterium halobium induces a catalase. The protein has been purified to electrophoretic homogeneity and has an M(r) of 240,000 and a subunit size of approximately 62,000. The enzyme is active over a broad pH range of 6.5 to 10.0, with a peak in activity at pH 7.0. It has an isoelectric point of 4.0. This catalse, which is not readily reduced by dithionite, shows a Soret peak at 406 nm. Cyanide and azide inhibit the enzyme at micromolar concentrations, whereas maleimide is without effect. The addition of 20 mM 3-amino-1,2,4-triazole results in a 33% inhibition in enzymatic activity. The tetrameric protein binds NADP in a 1:1 ratio but does not peroxidize NADPH, NADH, or ascorbate. Although the enzymatic activity is maximal when assayed in a 50 mM potassium phosphate buffer with no NaCl, prolonged incubation in a buffer lacking NaCl results in inactive enzyme. Moreover, purification must be performed in the presence of 2 M NaCl. Equally as effective in retaining enzymatic function are NaCl, LiCl, KCl, CsCl, and NH4Cl, whereas divalent salts such as MgCl2 and CaCl2 result in the immediate loss of activity. The catalase is stained by pararosaniline, which is indicative of a glycosidic linkage. The Km for H2O2 is 60 mM, with inhibition observed at concentrations in excess of 90 mM. Thus, the mesohalic catalase purified from H. halobium seems to be similar to other catalases, except for the salt requirements, but differs markedly from the constitutive halobacterial hydroperoxidase.

Enhanced superoxide production by membrane vesicles from Halobacterium halobium in a hyposaline environment.

Membrane vesicles were prepared from the halophilic archaebacterium, Halobacterium halobium, which was grown either in medium containing 4 M NaCl or in a relatively hyposaline medium containing 1.25 M NaCl. Membrane vesicles prepared from bacteria grown in the lower salt environment consumed more oxygen, oxidized more NADH and generated more superoxide than vesicles prepared from cells grown in the normal 4 M NaCl containing medium. The enhanced respiratory activity of the membrane fragments obtained from the halophile which was grown and assayed in a hyposaline environment, along with the concomitant increased flux in superoxide, demonstrate a relation between an environmental perturbation and an altered electron transport activity.

Purification of a catalase-peroxidase from Halobacterium halobium: characterization of some unique properties of the halophilic enzyme.

A hydroperoxidase purified from the halophilic archaeon Halobacterium halobium exhibited both catalase and peroxidase activities, which were greatly diminished in a low-salt environment. Therefore, the purification was carried out in 2 M NaCl. Purified protein exhibited catalase activity over the narrow pH range of 6.0 to 7.5 and exhibited peroxidase activity between pH 6.5 and 8.0. Peroxidase activity was maximal at NaCl concentrations above 1 M, although catalase activity required 2 M NaCl for optimal function. Catalase activity was greatest at 50 degrees C; at 90 degrees C, the enzymatic activity was 20% greater than at 25 degrees C. Peroxidase activity decreased rapidly above its maximum at 40 degrees C. An activation energy of 2.5 kcal (ca. 10 kJ)/mol was calculated for catalase, and an activation energy of 4.0 kcal (ca. 17 kJ)/mol was calculated for peroxidase. Catalase activity was not inhibited by 3-amino-1,2,4-triazole but was inhibited by KCN and NaN3 (apparent Ki [KiApp] of 50 and 67.5 microM, respectively). Peroxidative activity was inhibited equally by KCN and NaN3 (KiApp for both, approximately 30 microM). The absorption spectrum showed a Soret peak at 404 nm, and there was no apparent reduction by dithionite. A heme content of 1.43 per tetramer was determined. The protein has a pI of 3.8 and an M(r) of 240,000 and consists of four subunits of 60,300 each.

Results of a United States and Soviet Union joint project on nervous system effects of microwave radiation.

During the course of a formal program of cooperation between the United States and the Soviet Union concerning the biological effects of physical factors in the environment, it was concluded that duplicate projects should be initiated with the general goal of determining the most sensitive and valid test procedures for evaluating the effects of microwave radiation on the central nervous system. This report details an initial step in this direction. Male rats of the Fischer 344 strain were exposed or sham exposed to 10 mW/cm2 continuous wave microwave radiation at 2.45 GHz for a period of 7 hr. Animals were subjected to behavioral, biochemical, or electrophysiological measurements during and/or immediately after exposure. Behavioral tests used were passive avoidance and activity in an open field. Biochemical measurements were ATPase (Na+, K+; Mg2+, Ca2+) and K+ alkaline phosphatase activities. Electrophysiological measurements consisted of EEG frequency analysis. Neither group observed a significant effect of microwave irradiation on open field activity. Both groups observed changes in variability of the data obtained using the passive avoidance procedure, but not in the same parameters. The U.S. group, but not the USSR group, found significantly less Na+,K+-ATPase activity in the microwave-exposed animals compared to the sham exposed animals. Both groups found incidences of statistically significant effects in the power spectral analysis of EEG frequency, but not at the same frequency. The failure of both groups to substantiate the results of the other reinforces our contention that such duplicate projects are important and necessary.

Role of dentate gyrus cells in retention of a radial arm maze task and sensitivity of rats to cholinergic drugs.

Male adult Fischer-344 rats that received bilateral injections of colchicine into two rostrocaudal sites showed relatively long-lasting alterations in the performance of a previously acquired radial arm maze task and specific destruction of dentate granule cells. Results of subsequent experiments with cholinergic drugs indicated that physostigmine or nicotine had no effect on the number of errors made in the maze, although other signs of cholinergic or pharmacological activity were present. RS-86, an analog of the muscarinic agonist arecoline, decreased errors in colchicine-treated rats, but these effects were associated with signs of parasympathetic overstimulation and behavioral sedation. Pretreatment with scopolamine, a muscarinic cholinergic receptor antagonist, increased errors in control rats but had no effect in colchicine-treated rats. Results of subsequent experiments found that colchicine-treated rats were less sensitive to the motor stimulant effect of scopolamine. These effects appeared to be associated with increased levels of choline acetyltransferase in the hippocampus and a down regulation of muscarinic postsynaptic receptors. One interpretation of these data is that intradentate colchicine may destroy granule cells, which leads to a compensatory reinnervation of cholinergic nerve terminals having cell bodies in the septum.

Some behavioral effects of short-term exposure of rats to 2.45 GHz microwave radiation.

Rats were tested for neurobehavioral alterations immediately after exposure to 2.45-GHz (CW) microwave radiation at 10 mW/cm2 for 7 h. Behavioral tests used were locomotor activity, startle to an acoustic stimulus and acquisition and retention of a shock-motivated passive avoidance task. Both horizontal and vertical components of locomotor activity were assessed in 5-min epochs for a period of 30 min using photoelectric detectors. Microwave-exposed animals exhibited less activity than sham-exposed animals. This was most evident during the last 10-15 min of the 30-min test session. Twenty identical acoustical stimuli (8 KHz, 110 dB) were delivered to each rat at 40-s intervals. The microwave-exposed animals were less responsive to the stimuli than sham-exposed animals. Microwave exposure had no effect on the retention of a passive avoidance procedure when tested at 1 week after training. Both the locomotor activity and acoustic startle data demonstrate that, under the conditions of this experiment, microwave exposure may alter responsiveness of rats to novel environmental conditions or stimuli.

Colchicine as an investigative tool in neurobiology.

Neurotoxicants are being used with increasing frequency in neurobiology as investigative tools to study the structure and function of the nervous system. Colchicine administered directly into the hippocampus produces preferential destruction of dentate gyrus granule cells and mossy fibers and affects conditioned behavior. Studies from our laboratory have demonstrated the dose- and time-dependent loss of dentate gyrus granule cells and stimulation of motor activity following intradentate administration of colchicine. Preferential degeneration of pyramidal cells and other morphological changes observable at the light microscopic level were not seen in colchicine-treated rats. Other studies showed that intradentate colchicine produces specific damage to granule cells in both the dorsal and ventral hippocampus and that this damage is associated with depletion of dynorphin, a neuropeptide preferentially localized in the granule cells and mossy fibers of the hippocampus. Finally, it was noted that there are compensatory changes in the nervous system following treatment with colchicine and that the behavioral effects of colchicine can be modified by factors such as handling. One potentially important compensatory change occurring after intradentate colchicine is an alteration in cholinergic function. Pharmacological studies suggest that colchicine-treated rats may be less sensitive to the behavioral effects of scopolamine. These experiments support the conclusion that given at the appropriate dose into the hippocampus, colchicine may be a useful investigative tool to study the function of the dentate gyrus granule cells and mossy fibers, as well as the compensatory changes in the nervous system that follow chemical-induced neurodegeneration.

Time-dependent neurobiological effects of colchicine administered directly into the hippocampus of rats.

Rats were given bilateral injections of colchicine into the dorsal and ventral hippocampus. Behavioral, neurochemical and histopathological measurements were taken, up to 12 weeks after surgery. Colchicine produced a consistent increase in spontaneous motor activity, enhanced acoustic startle reactivity, and accelerated acquisition of two-way shuttle box avoidance, but did not affect reactivity to a noxious thermal stimulus. Measurement of dynorphin in the hippocampus indicated that colchicine rapidly depleted this neuropeptide, which is thought to be contained preferentially in the mossy fibers of granule cells of the hippocampus. Colchicine also decreased Met-enkephalin in the hippocampus, but the magnitude of the change (22%) was less than that (89% depletion) observed for hippocampal dynorphin. Examination of hippocampal morphology using light microscopic techniques indicated that colchicine caused approximately 60% degeneration of granule cells in the hippocampus. Although the length of the pyramidal cells was decreased (12-16%), the width of the CA1 and CA3 region of the hippocampus was not affected. These data underscore the importance of the granule cells in the mediation of behavioral processes such as motor activity, startle reactivity and performance of shuttle box avoidance.

Transmission of type B viral hepatitis via eye inoculation of a chimpanzee.

To simulate a splash of infectious material in the eyes, plasma from a hepatitis B patient was placed on the corneal surfaces of a chimpanzee. The animal became infected 9 weeks later. This result indicates a need for the use of eye protection in high-risk areas, such as clinical laboratories, hemodialysis units, and dental operatories.

Peritonitis due to a mycobacterium chelonei-like organism associated with intermittent chronic peritoneal dialysis.

Two outbreaks of peritonitis caused by a Mycobacterium chelonei-like organism--a previously unrecognized pathogen--occurred among patients receiving intermittent chronic peritoneal dialysis (CPD). In one center, five of 22 patients who had undergone CPD during a one-month period developed peritonitis caused by an M. chelonei-like organism acquired from a single contaminated automated CPD machine. In a second center, five of eight patients who had received CPD during a several-week period became infected, apparently as a result of cross-infection from contaminated machines. Seven sporadic cases of peritonitis due to an M. chelonei-like organism were also found. M. chelonei-like organisms can survive and proliferate in water and are relatively resistant to formaldehyde. Defects in the design of CPD machines and disinfection procedures were identified that may have permitted M. chelonei-like organisms to survive attempted disinfection.