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Biomedical subjects

R F Smith

Publications and source records attributed to R F Smith.

At least 307 records · Page 17Linked to original sources
PubMedDate not supplied

Periadolescent alcohol alters adult behavioral characteristics in the rat.

Long-Evans hooded rats were given 5% alcohol (EtOH), 10% EtOH or tap water as sole fluid from postnatal day 21 (P21) to P70. The 10% EtOH group drank 26% less and 10% EtOH males gained 7.6% less weight than the tap water control group. There were no significant consumption or weight differences between 5% EtOH and control subjects. At P105, 35 days after the conclusion of alcohol dosing, we conducted several behavioral tests. Males in the 10% group drank 67.8% more alcohol than controls in a two-bottle preference test. On a DRL-20-s operant reinforcement schedule, a difficult timing task dependent upon limbic structures, subjects in the 10% group had higher barpress rates, while those in the 5% group had lower barpress rates than controls. On this task, 10% females received fewer reinforcements, while both 5% and 10% males earned more reinforcements than controls. Efficiency ratios were lowest for 10% females and highest for 5% males. Males in the 5% group had shorter latencies than controls to find the platform in a Morris water maze and were significantly more likely than controls to initially find the platform. These data suggest that EtOH consumption during periadolescent development may have long-lasting neurobehavioral effects.

Age Factors↗
PubMedDate not supplied

Outcome in an urban pediatric trauma system with unified prehospital emergency medical services care.

HYPOTHESIS: Pediatric mortality is predicted by age, presence of head trauma, head trauma with a low Glasgow Coma Scale (GCS) score, a low Pediatric Trauma Score (PTS), and transport directly to a pediatric trauma center. POPULATION: Studied were 1,429 patients younger than 16 years old admitted to or declared dead on arrival (DOA) in a pediatric trauma center from January through October, 1988. The trauma system, which served 3-million persons, included six pediatric trauma centers. METHODS: Data were obtained by a retrospective review of summary statistics provided to the Chicago Department of Health by the pediatric trauma centers. RESULTS: Overall mortality was 4.8% (68 of 1429); 32 of the patients who died (47.1%) were DOA. The in-hospital mortality rate was 2.6%. Head injury was the principal diagnosis in 46.2% of admissions and was a factor in 72.2% of hospital deaths. The mortality rate was 20.3% in children with a GCS < or = 10 and 0.4% when the GCS was > 10 (odds ratio [OR] = 67.0, 95% CI = 15.0-417.4). When the PTS was < or = 5, mortality was 25.6%; with a PTS > 5, the mortality was 0.2% (OR = 420.7, 95% CI = 99.3-2,520). Although transfers to a pediatric trauma center accounted for 73.6% of admissions, direct field triage to a pediatric trauma center was associated with a 3.2 times greater mortality risk (95% CI = 1.58-6.59). Mortality rates were equal for all age groups. Pediatric trauma center volume did not influence mortality rates. CONCLUSIONS: Head injury and death occur in all age groups, suggesting the need for broad prevention strategies. Specific GCS and PTS values that predict mortality can be used in emergency medical services (EMS) triage protocols. Although the high proportion of transfers mandates systemwide transfer protocols, the lower mortality in these patients suggests appropriate EMS field triage. These factors should be considered as states develop pediatric trauma systems.

Adolescent↗
PubMedDate not supplied

Electrophysiology of O-demethyl encainide in a canine model of sustained ventricular tachycardia.

The antiarrhythmic agent encainide produces marked suppression of ventricular arrhythmias in most patients. However, in some with sustained ventricular tachycardia, worsening of clinical arrhythmias can occur. Since the effects of this agent are mediated by its O-demethyl metabolite in most patients, we have evaluated the effects of O-demethyl encainide in dogs susceptible to the induction of ventricular tachycardia. Nonsedated animals were studied 3-5 days after 90-min left anterior descending coronary artery occlusions. Electrophysiologic evaluations were carried out at baseline, and then during a series of infusions of O-demethyl encainide that achieved low (58 +/- 5 ng/ml) (mean +/- SE), moderate (190 +/- 16 ng/ml), and high (758 +/- 98 ng/ml) plasma concentrations compared with the range seen in patients (50-300 ng/ml). Ventricular tachycardia induction was unaffected by the drug. Effective refractory period was prolonged in a dose-related fashion at both normal and infarcted epicardial sites. However, local electrogram duration was prolonged only in the infarcted zone. We conclude that O-demethyl encainide exerted no consistent effect on susceptibility to induction of ventricular tachycardia in this study. This agent appears to alter infarcted zone conduction disproportionately.

Anilides↗
PubMedDate not supplied

The etiology of nongonococcal urethritis in men attending a venereal disease clinic.

Nongonococcal urethritis was identified as a major reason that men attended our Venereal Disease Clinic. The prevalence of several agents that might cause nongonococcal urethritis was determined. Attempts were made to isolate gonococci; chlamydiae, Ureaplasms urealyticum, trichmonads, Candida sp., and Corynebacterium vaginale from urethral swabs from 307 men. Chlamydiae were recovered from 31% of the 67 men with nongonococcal urethritis compared to only 4% of 86 asymptomatic men without pyuria. Unexpectedly, cultures from only 4% of the 99 men with gonorrhea also yielded chlamydiae. Ureaplasma urealyticum was recovered from 9 of 27 asymptomatic men (33%), 16 of 30 men with nongonococcal urethritis (53%) and 16 of 68 men with gonorrhea (42%). These differences were not statistically significant. However, when chlamydiae-positive men were excluded from the analysis urethritis. Twelve of 18 (76%) men with nononchlamdial nongonococcal urethritis yielded the organism compared to 8 of 26 (31%) men without urethritis. The other organisms sought were recovered infrequently and could not be associated with nongonococcal urethritis.

Adult↗
PubMedDate not supplied

Inhibition of Corynebacterium vaginale by metronidazole.

Metronidazole [1-(2-hydroxyethyl)-2-methyl-5-nitroimidazole], previously thought to only inhibit obligately anaerobic bacteria, was found in vitro, to inhibit the growth of 15 facultatively anaerobic strains of Corynebacterium vaginale (Haemophilus vaginalis) using agar disk diffusion and broth dilution methods.

Corynebacterium↗
PubMedDate not supplied

Haemophilus vaginalis (Corynebacterium vaginale) vaginitis in women attending public health clinics: response to treatment with ampicillin.

Haemophilus vaginalis (Corynebacterium vaginale) was isolated from genital specimens from 150 women who came to a public health venereal disease clinic. Forty-six patients returned to the clinic for at least one follow-up examination. Of the returnees, 22 of 24 who initially had received adequate therapy (14 g ampicillin in seven days) were cured, compared with three of 22 who did not received adequate therapy (X2 = 25.11; P less than 0.00005). These data included significant cure rates with adequate therapy among the 46 returnees, of whom 25 had vaginitis due to H. vaginalis only (X2 = 16.67; P less than 0.00005) and 21 had vaginitis caused by a mixture of pathogens (X2 = 5.86; P less than 0.0156). Specimens obtained from 24 of the 46 returnees were cultured for H. vaginalis on the second visit; 19 were negative, and only five were positive. Clinical responses of the patients correlated closely with the results of culture in both treated and untreated groups (X2 = 14.23; P less than 0.00016).

Adolescent↗
PubMedDate not supplied

Inhibition of some normal and pathogenic vaginal bacteria by oral and vaginal streptococci.

Hemolytic and nonhemolytic strains of Streptococcus faecalis, together with some strains of oral and vaginal alpha-hemolytic streptococci, produced one or more factors that inhibited the growth of Gardnerella vaginalis, Neisseria gonorrhoeae, and a variety of other vaginal bacteria. Some streptococci were inhibitory to indicator organisms only in the presence of catalase, whereas catalase either enhanced or prevented inhibitory action for still other streptococci. The inhibitors produced by certain streptococci resembled enterococcal bacteriocins, which have not previously been found to inhibit G. vaginalis or N. gonorrhoeae.

Bacteria↗
PubMedDate not supplied

Measuring the in vitro susceptibility of Trichomonas vaginalis to metronidazole: a disk broth method.

Strains of Trichomonas vaginalis were evaluated for their in vitro responses to metronidazole. A serial twofold dilution method that measured minimal inhibitory concentrations (MICs) by cessation of trophozoite motility was compared with the disk broth method, in which both cessation of motility and inhibition of trophozoite proliferation were used for measurement of MICs. These methods gave comparable results in distinguishing a metronidazole-resistant and two metronidazole-susceptible strains of T. vaginalis under conditions of both aerobic and anaerobic incubation. However, anaerobic test conditions significantly lowered the MIC of metronidazole against a metronidazole-resistant strain. Clinical isolates of T. vaginalis and strain ATCC 30001 from the American Type Culture Collection (Rockville, Md.) were also tested. Two of 12 clinical isolates were resistant to metronidazole in vitro. It is concluded that the disk broth method is a simple and reliable screening method for detection of metronidazole-resistant strains of T. vaginalis.

Drug Resistance, Microbial↗
PubMedDate not supplied

Inhibition of Trichomonas vaginalis by fungi during associative growth.

In controlled studies of associative growth, Candida albicans and Torulopsis glabrata, but not Candida parapsilosis, inhibited the proliferation and eventually the viability of Trichomonas vaginalis. The inhibition patterns produced against the trichomonad by C. albicans or T. glabrata were observed with trichomonad-fungus inoculum ratios ranging from 230:1 to 1:100. The onset of inhibition of T. vaginalis by T. glabrata was immediate, whereas that of C. albicans began after incubation for 48 hr. Under routine clinical conditions, T. vaginalis was identified by a combination of direct microscopy and culture in specimens from 330 (19.5%) of 1,691 women with vaginal discharges who were examined. Trichomonas vaginalis was isolated from 49 of 53 vaginal discharge specimens that also contained C. albicans. Therefore, the qualitative results with clinical cultures did not confirm the inhibition of trichomonads by C. albicans as shown in quantitative studies of associative growth. This result indicates that with the routine clinical isolation procedures the use of an antifungal agent in medium for culture of T. vaginalis is not necessary.

Candida↗
PubMedDate not supplied

Study of the ventilation of middle ear using radioactive xenon.

The greatest contribution of nuclear medicine has been to make possible dynamic measurements of regional function. It is conceivable that if this technology could be successfully used to measure the ventilation and clearance of the middle ear, answers to some of the most crucial problems in otology may be found. The objectives of this paper are three-fold: 1) A descriptive account of radiotracers and radiodetectors with emphasis on Xenon133. 2) The development of scintillographic techniques for the dynamic study of the ventilation of the ear and sinuses. 3) The methods that are being explored for the quantification of these functions.

Ear, Middle↗
PubMedDate not supplied

Behavioral effects of mid-pregnancy administration of lidocaine and mepivacaine in the rat.

Sperm-positive female Long-Evans hooded rats were injected with 6 mg/kg lidocaine (with epinephrine), 6 mg/kg mepivacaine, or saline, into the masseter muscle of the jaw on Day 11 of gestation. Birth, growth, and litter composition were unaffected by the drug treatment, as was shuttle box acquisition. Offspring of drug-treated dams had longer latencies than controls on the first day of negative geotaxis training, and were more sensitive to electric footshock. Lidocaine-dosed offspring responded less in the presence of the correct cue in the visual discrimination task, and mepivacaine-dosed animals were hypoactive in the open field. In a second study, offspring of lidocaine-dosed dams were slower to develop the righting reflex, made more errors in acquiring a water maze, had longer suppression times in a conditioned suppression task, and had longer latencies in the tail flick test. Dosing had no effect upon birth and growth, shuttle box, or footshock sensitivity. These data demonstrate that midgestational exposure to lidocaine or mepivacaine at a dose near the limits of permissible human exposure produces significant behavioral changes in the offspring. This preliminary study suggests that development of some portion of the central nervous system is altered by such exposure. Further work is required to determine the parameters and the extent of the effect.

Animals↗
PubMedDate not supplied

Behavioral correlates of soman-induced neuropathology: deficits in DRL acquisition.

Rats (N = 45) pretrained to lever press for milk reinforcement on a continuous reinforcement (CRF) schedule were injected with 100-110 micrograms/kg of the anticholinesterase soman (N = 24) or saline (N = 21) SC. Subjects exposed to soman experienced moderate to severe acute symptoms of anticholinesterase intoxication. After a 3 week recovery period, all surviving subjects were retrained on CRF, then given 45 training sessions on a differential reinforcement of low rates (DRL) 20 sec schedule, followed by 10 sessions of extinction. Brains of all subjects were then examined for evidence of neuropathology. Subjects exposed to soman showed no improvement over sessions in the number of reinforcements earned on the DRL schedule due to an inefficient patterning of responses. There were no differences between groups in the number of total DRL responses or terminal extinction responses. Neuropathology was most evident in dorsal thalamic areas, primary olfactory/piriform cortex and amygdala of subjects exposed to soman. There were significant correlations between the severity of acute intoxication scores, degree of neuropathology, and deficits in DRL performance. The results demonstrate that exposure to high doses of this anticholinesterase agent can result in neural damage and persistent decrements in performance of certain operant tasks.

Animals↗