Polychlorinated biphenyl concentrations of burbot Lota lota from Great Slave Lake are very low but vary by sex.

Total polychlorinated biphenyl concentrations (ΣPCBs) in whole fish were determined for 18 ripe female burbot Lota lota and 14 ripe male burbot from Great Slave Lake, a lake with no known point sources of PCBs. In addition, ΣPCBs were determined in both somatic tissue and gonads for a randomly selected subset of 5 females and 5 males. Mean ΣPCBs for females and males were 2.89 and 3.76 ng/g, respectively. Thus, males had 30 % greater ΣPCBs than females. Based on ΣPCB determinations for somatic tissue and gonads, ΣPCBs of females and males would be expected to decrease by 18 % and increase by 6 %, respectively, immediately after spawning due to the release of gametes. Results from a previous study in eastern Lake Erie indicated that males had 28 and 71 % greater ΣPCBs than females from populations of younger (ages 6-13 years) and older (ages 14-17 years) burbot, respectively. Thus, although younger burbot from Lake Erie had approximately 50 times greater ΣPCBs than Great Slave Lake burbot, the relative difference in ΣPCBs between the sexes was remarkably similar across both populations. Our results supported the contention that the widening of the difference in ΣPCBs between the sexes in older burbot from Lake Erie was attributable to a "hot spot" effect operating on older burbot because Lake Erie has received PCB point source loadings. Our results also supported the contention that male fish expend energy at a rate between 15 and 30 % greater than females. Eventually, these results will be useful in developing sex-specific bioenergetics models for fish.

Sex difference in polychlorinated biphenyl concentrations of burbot Lota lota from Lake Erie.

Whole-fish polychlorinated biphenyl (PCB) concentrations were determined for 25 female and 25 male burbot Lota lota from Lake Erie. Bioenergetics modeling was used to investigate whether the sex difference in growth rate resulted in a difference in gross growth efficiency (GGE) between the sexes. For ages 6-13 years, male burbot averaged 28 % greater PCB concentrations than female burbot. The sex difference in PCB concentrations widened for ages 14-17 years, with male burbot having, on average, 71 % greater PCB concentrations than female burbot. Bioenergetics modeling results showed that the faster growth rate exhibited by female burbot did not lead to greater GGE in female individuals of the younger burbot and that the faster growth by female fish led to female GGE being only 2 % greater than male GGE in older burbot. Although our bioenergetics modeling could not explain the observed sex difference in PCB concentrations, we concluded that a sex difference in GGE was the most plausible explanation for the sex difference in PCB concentrations of burbot ages 6-13 years. Not only are male fish likely to be more active than female fish, but the resting metabolic rate of male fish may be greater than that of female fish. We also concluded that the widening of the sex difference in PCB concentrations for the older burbot may be due to many of the older male burbot spending a substantial amount of time in the vicinity of mouths of rivers contaminated with PCBs.

Polychlorinated biphenyl concentrations and activity of sea lamprey Petromyzon marinus vary by sex.

We determined the polychlorinated biphenyl (PCB) concentrations of 40 male and 40 female adult sea lampreys Petromyzon marinus captured in the Cheboygan River, a tributary to Lake Huron, during May 2011. In addition, we performed a laboratory experiment using passive integrated transponder tags to determine whether male adult sea lampreys were more active than female adult sea lampreys. Sex had a significant effect on PCB concentration, and PCB concentration at a given level of sea lamprey condition was approximately 25 % greater in males than in females. Adjusting for the difference in condition between the sexes, males averaged a 17 % greater PCB concentration compared with females. Results from the laboratory experiment indicated that males were significantly more active than females. The observed sex difference in PCB concentrations was not due to female sea lampreys releasing eggs at spawning because the sea lamprey is semelparous, and we caught the sea lampreys before spawning. Rather, we attributed the sex difference in PCB concentrations to a greater rate of energy expenditure in males compared with females. We proposed that this greater rate of energy expenditure was likely due to greater activity. Our laboratory experiment results supported this hypothesis. A greater resting metabolic rate may also have contributed to a greater rate of energy expenditure. Our findings should eventually be applicable toward improving control of sea lamprey, a pest responsible for considerable damage to fisheries in lakes where it is not native.

Patients' fear of contracting the acquired immunodeficiency syndrome from physicians.

This study investigates patients' concern about the human immunodeficiency virus transmission from their physician during the course of routine medical care. We examined patients' fear of acquired immunodeficiency syndrome (AIDS), knowledge of human immunodeficiency virus transmission, level of comfort with medical procedures performed by a physician suspected of having AIDS, perceived risk of AIDS transmission in physician-patient interactions, and the desire to be informed of the human immunodeficiency virus status of physicians. Three hundred fifty patients attending a university-based outpatient center in a large midwestern city were surveyed. Findings show that, as fear of AIDS increases, so does reported level of discomfort with procedures conducted by a physician suspected of having AIDS. Fear of AIDS was inversely correlated with knowledge. Patient concerns regarding susceptibility to the human immunodeficiency virus infection in routine care call attention to the need for education about transmission of AIDS in the health care context.

Molecular analysis of human cytomegalovirus strains from two lung transplant recipients with the same donor.

A total of four cytomegalovirus (CMV) isolates were obtained from two CMV seronegative patients, each of whom received a lung transplant from the same seropositive donor. CMV was isolated from Patient 1 from two bronchial alveolar lavage (BAL) specimens, one obtained during treatment with ganciclovir (GCV) and a second during later treatment with foscarnet. Both of these isolates are sensitive to GCV and foscarnet. CMV was isolated from Patient 2 from a blood and a BAL specimen obtained during treatment with GCV. Both of these isolates are resistant to GCV and show reduced GCV phosphorylation. Patient 1 is still alive 33 months posttransplant. Patient 2 died 6 1/2 months posttransplant. Although the four strains differ with respect to GCV susceptibility and phosphorylation, their DNA restriction fragment hybridization patterns and UL97 kinase gene sequences indicate that they are closely related. The restriction fragment hybridization patterns are identical among the strains, while these patterns differ markedly from those of unrelated strains. The DNA sequences of the UL97 genes of the strains from Patient 2 differ by only one nucleotide from those of Patient 1. The same comparison with unrelated strains shows a minimum of 12 nucleotide differences. The nucleotide change in the strains from Patient 2 produces an amino acid substitution of serine for leucine at residue 595, a substitution that was previously shown to transfer GCV resistance. Both patients, therefore, were apparently infected with the same donor strain, but during the course of GCV prophylaxis and treatment, a GCV-resistant mutant strain was selected in Patient 2.

Antimicrobial susceptibility patterns of the Bacteroides fragilis group in the United States, 1989.

A national survey of Bacteroides fragilis group was continued in 1989 for the ninth consecutive year. Seven hundred thirty-nine isolates of B fragilis group from eight centers were tested for susceptibility to 14 antimicrobials. Sulbactam and clavulanic acid, beta-lactamase inhibitors, were tested at a constant concentration of 8 micrograms/ml and 2 micrograms/ml, respectively. Sulbactam was also tested in a fixed ratio of 1:2. Imipenem, ampicillin+sulbactam, and ticarcillin+clavulanic acid had resistance of less than 1% at breakpoints of 8 micrograms/ml, 16 micrograms/ml, and 64 micrograms/ml, respectively. At 32 micrograms/ml, resistance to cefoxitin, cefotetan, ceftizoxime, and ceftriaxone were 4%, 25%, 26%, and 46%, respectively. Clindamycin resistance was 10% at a breakpoint of 4 micrograms/ml. No isolates were resistant to chloramphenicol or metronidazole. Resistance for five B fragilis species to cefoxitin, ceftizoxime, and cefotetan varied greatly among both species and participating institutions. The addition of a beta-lactamase inhibitor increased the potency of the beta-lactam drugs tested as combinations. This finding suggests that beta-lactamase production is the major resistance factor in members of the B fragilis group.

Medical students' first-person narratives of a patients story of AIDS.

Fourth year U.S. medical students' first-person narratives of a patient's experience of AIDS are analyzed using a conceptual framework that builds on the interactive model of narrative critique. Relational and affective convergence and, conversely, relational and affective dissonance, reveal imaginative reconstructions of emotional and interactional themes depicted in the patient's original story. Attention is focused on representations of isolation, contamination, shame and fear. Elements of indeterminacy and openness in the patient's description of his experience with AIDS provided students with opportunities to create an imagined response to HIV infection in their own narratives. The narratives describe social interaction that is tainted and constrained by the presence of infection and its associated stigma. The emotional content of the student narratives portrays an affective landscape that resonates. elaborates and, in some cases, distorts the feelings expressed in the patient's story. The narratives call attention to the way in which individual meanings are externalized, objectified and projected onto a socially and morally salient 'other'. Using the first-person narrative approach in the seminar on AIDS proved to be an effective method of sensitizing students to the experience of living with HIV infection. The challenge for medical educators lies in creating opportunities for students to develop increased empathy toward individuals with AIDS.

Single dose amoxicillin treatment of acute otitis media.

A double blind study comparing a single dose of amoxicillin versus a 10-day course of amoxicillin in the treatment of acute otitis media (AOM) was undertaken. All children diagnosed with AOM in a pediatric clinic were requested to participate. After tympanocentesis was performed, patients were randomly assigned to receive either amoxicillin (100 mg/kg) followed by placebo every 8 hours for 10 days or placebo followed by amoxicillin (40 mg/kg/D) for 10 days. Patients returned to clinic on days 3 and 10 post-treatment. Seventeen patients were enrolled: 7 received single dose therapy and 10 received 10 days of therapy. There were no failures in the control group and 3 failures in the single dose group (day 5, day 6, and 11) (p = 0.05). Middle ear isolates included: S. pneumoniae 7, H. influenzae 4, B. catarrhalis 1, and no pathogen in 5. Due to the significant number of failures in the treatment group, the study was prematurely terminated.

Microbiologic considerations in the treatment of serious pelvic infections in women.

Antibiotic therapy in the woman with suspected pelvic inflammatory disease (PID) may often be empiric. Thus, an understanding of the microbiology of the female genital tract is important in the informed selection of therapy for PID. Chlamydia trachomatis plays an important role in PID, and tetracycline and erythromycins are the agents most active against those infections. Neisseria gonorrhoeae is also an important pathogen in PID, particularly in a lower socioeconomic, urban setting. The treatment regimens currently recommended for penicillinase-producing N gonorrhoeae are spectinomycin and a broad-spectrum cephalosporin. Other bacterial flora of the female genital tract, including the facultative enteric bacilli, gram-positive aerobes and anaerobes, play an important pathogenic role in PID. Among the broad-spectrum cephalosporins, ceftizoxime has been shown to possess greater activity against isolates of the Bacteroides fragilis group and enteric bacilli than do the related agents, cefoxitin and cefotetan.

A study of factors affecting dental expenditures in Quebec: 1962-1991.

The issue of dental manpower planning has received considerable attention in Quebec in recent years. Quebec dentists agree that there is a need for detailed information regarding the impact of economic factors on the supply of and demand for dental care in the province. This study examines the impact of economic factors on dental care expenditures in Quebec between 1962 and 1991. The functional form of the econometric model used by the authors is similar to the one used in a study of the growth of the U.S. dental sector between 1950 and 1989. The dependent variable is per capita dental expenditure, and the three independent variables are: dentist/population ratio, per capita personal disposable income; and percentage of the population with dental insurance coverage. All data come from secondary sources. The findings indicate that per capita dental expenditure has grown substantially in Quebec over the past three decades, with the rate of growth slowing dramatically during the 1980s. Dental insurance coverage, the number of dentists in the community and the disposable income of the population all have a positive impact on dental expenditure in Quebec. However, it is clear that the incomes of Quebec dentists may decrease in the future if: no restrictions are placed on the number of new dental graduates entering the profession; dental insurance programs are curtailed; or dental disease levels continue to fall.

Self-treatment with antibiotics.

Two hundred seventy patients who presented with symptoms assumed to be infectious in origin were evaluated for self-treatment with antibiotics. Urine was tested for the presence of antimicrobials by agar diffusion assay using Bacillus subtilis as the test organism. Seventeen patients (6%) were found to have antibiotic activity in their urine, but only five admitted to self-medication. Age, sex, and duration of symptoms were unrelated to the incidence of self-medication. Self-medication was seen more frequently in patients presenting with upper respiratory infection symptoms (12%) when compared to other symptom complexes (P less than .002). This study suggests that self-medication with antibiotics can be an important problem in patients who present to emergency departments, as this practice could have an impact on clinical diagnosis and bacterial cultures.

A case of cutaneous tuberculosis: primary or secondary?

A case of cutaneous tuberculosis in a 24-yr-old Mexican man occurring after a penetration injury is presented. Classification and pathogenesis of cutaneous tuberculosis are reviewed. The disease in the patient described had features overlapping the classification schemes, and the exact pathogenesis remains unclarified.

Activity of newer beta-lactam agents against clinical isolates of Bacteroides fragilis and other Bacteroides species.

The in vitro activities of beta-lactam antibiotics against Bacteroides fragilis and B. fragilis group isolates are presented. Clinical isolates from 1986 were compared with strains from 1979 to 1982. Imipenem, ticarcillin-clavulanic acid, and ceftizoxime were the most active agents. Cefotetan was equivalent to cefoxitin against B. fragilis but less active against B. fragilis group isolates. Enhancement of cefotaxime by its desacetyl metabolite was minimal.

Variation in the susceptibility of Bacteroides fragilis group isolates from six Chicago hospitals.

The antimicrobial susceptibility of isolates of the Bacteroides fragilis group from six hospitals in the Chicago area varied from one institution to another; this variation was similar to the geographic variation documented in a national survey. A total of 365 B. fragilis group isolates were tested against 10 antibiotics. Imipenem, piperacillin/tazobactam, ampicillin/sulbactam, ticarcillin/clavulanate, and cefoperazone/sulbactam had excellent activity against all members of the B. fragilis group, with little interhospital variation. Cefoxitin and ceftizoxime had very good activity, also with little variation among hospitals. Clindamycin, cefotetan, and cefmetazole had the lowest level of activity, with unusually high-level resistance confined to three of the six hospitals. These data indicate that variation in the antimicrobial susceptibility of these bacteria is likely based in the hospital rather than in the geographic region and that the in vitro activity of certain antibiotics against B. fragilis group isolates from individual hospitals cannot be predicted from the data obtained in larger-scale surveys.

Penetration of cephalothin and cefoxitin into experimental infections with Bacteroides fragilis.

The in vitro activities of cephalothin and cefoxitin against Bacteroides fragilis were studied by time-kill curves and measurement of residual drugs in culture supernatants. Cefoxitin was bactericidal, causing a decrease of 10(7) in viable counts over 24 hr. Cephalothin caused an initial decrease of 10(2) B. fragilis at 2 hr; this change was followed by growth of the organism within 24 hr back to the number present before addition of cephalothin. The concentration of cephalothin in broth decreased rapidly within 2 hr and was undetectable within 24 hr, whereas the level of cefoxitin decreased only 25% over the 24-hr period. Penetration of these drugs into perforated ping pong balls implanted intraperitoneally in rabbits was studied. Three weeks after implantation the reservoirs were infected with B. fragilis. After intramuscular administration of five doses of antibiotic, the penetration of cephalothin, as measured by bioassay, in uninfected and infected capsules was 16% and 2%, respectively, of the peak serum concentration; similar findings were noted with cefoxitin. For determination of the rate of breakdown within the infected site, radiolabeled antibiotic was injected into the capsule, and the concentrations of bioactive and radioactive drug were determined. With radiolabeled cephalothin there was a rapid decrease in bioactivity during the initial 60 min, and no active drug was measurable after 2 hr. In contrast, only 40% of cefoxitin was inactivated at the end of 6 hr. The results indicate that levels of cephalothin and cefoxitin are reduced significantly in sites infected with B. fragilis. The decrease appears to be mediated by both a decrease in penetration and inactivation at the site of infection.

Inactivation of penicillin G during experimental infection with Bacteroides fragilis.

An animal model implanted with intraperitoneal plastic reservoirs was used for study of the penetration of penicillin G into sites infected with Bacteroides fragilis. Penicillin G was given to rabbits, and its concentration in uninfected reservoirs and in those infected with B. fragilis was determined. The mean percentage penetration ([concentration in capsule divided by peak concentration in serum] X 100) of penicillin into uninfected capsules was 19.9%, whereas that into heavily infected capsules was 1.5%. The percentage penetration of radiolabeled penicillin into infected capsules was 12.5%, whereas the proportion of bioactive drug in the same capsules was again very low (1%). These results show that there is a modest reduction in penetration of penicillin into infected sites and a striking inactivation of the drug by B. fragilis in this experimental model.

Inactivation of cephalosporins by Bacteroides.

We investigated the relationship between beta-lactamases of Bacteroides fragilis organisms and their resistance to cephalosporins. Timed killing curves were used to study the in vitro activity of three cephalosporins, cephalothin, cefazolin, and cefamandole, and a semisynthetic cephamycin, cefoxitin. Measurements of residual antibiotic concentrations in culture supernatants were made, and they were compared with the beta-lactamase activity of the microorganism. A cephalosporin-susceptible strain was rapidly killed by cephalothin, cefazolin, cefamandole, and cefoxitin. Four cephalosporin-resistant strains were not killed by cephalothin, cefazolin, or cefamandole but were killed by cefoxitin. An inoculum effect was noted with cefazolin and not with cefoxitin. The resistant strains of Bacteroides inactivated the three cephalosporins, but there was no inactivation of cefoxitin. A constitutive beta-lactamase was detected in all the isolates of the B. fragilis group that were resistant to the cephalosporins. There was no distinction of the species based on isoelectric focusing of the enzyme. These data suggest that inactivation by beta-lactamase may be the mechanism for resistance of B. fragilis to the cephalosporins and would explain the enhanced in vitro activity of cefoxitin.

Activity of metronidazole and its hydroxy and acid metabolites against clinical isolates of anaerobic bacteria.

Susceptibility of clinical isolates of anaerobic bacteria to metronidazole and its two oxidation products, 1-(2-hydroxyethyl)-2-hydroxymethyl-5-nitroimidazole (the "alcohol" metabolite) and 2-methyl-5-nitroimidazole-1-acetic acid (the "acid" metabolite), were determined by the agar dilution technique. Results disclosed that the alcohol metabolite, although less active than metronidazole, inhibited the organisms tested at levels considered susceptible for metronidazole. The acid metabolite was less active, not inhibiting the organisms at levels within the susceptible range. In other studies, mixtures of known concentrations of metronidazole and the metabolites were assayed in a bioassay system used to measure metronidazole levels. These studies showed that the bioassay will measure metronidazole or the alcohol metabolite; the acid metabolite is not measured at levels achieved in clinical specimens. Since the activity of the alcohol metabolite is comparable to that of metronidazole, we feel that microbiological assays can be used for therapeutic monitoring of metronidazole levels in clinical situations.

Transient Passovoy defect during a febrile illness.

The Passovoy defect is a recently characterized hemorrhagic diathesis. We describe a patient with a febrile illness, possibly from Epstein-Barr (EB) virus, who acquired this defect transiently. Prothrombin time; assays for factors VIII, IX, XI, XII; and Fletcher (prekallikrein) and Fitzgerald (high molecular weight kininogen) factors were normal. No definite circulating inhibitor could be demonstrated. The transient Passovoy defect could possibly be ascribed to the infectious process or sulfisoxazole, which the patient had received.