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Biomedical subjects

N Squires

Publications and source records attributed to N Squires.

18 recordsLinked to original sources
PubMed2000

Interventions for treating schistosomiasis haematobium.

BACKGROUND: Schistosomiasis is a parasite that is carried by freshwater snails. There are two common forms, urinary schistosomiasis (which is considered in this review) and intestinal schistosomiasis. OBJECTIVES: The objective of this review was to assess the effects of drugs for treatment of Schistosomiasis haematobium. SEARCH STRATEGY: The Cochrane Infectious Diseases Group trials register, Medline and reference lists of articles were searched. The WHO Division of Control of Tropical Diseases was contacted. SELECTION CRITERIA: Randomised trials of metrifonate or praziquantel or other drugs for treating Schistosomiasis haematobium. DATA COLLECTION AND ANALYSIS: One reviewer assessed trial quality and extracted data, and this was checked by a review editor. MAIN RESULTS: Five trials, all from Africa, were included. The quality of the trials was variable. There were no good randomised controlled trials of praziquantel single dose treatment versus current standard treatment with metrifonate of three doses of 10 milligrams per kilogram at two weekly intervals. Praziquantel at doses of 40 milligram per kilogram was more effective than single dose metrifonate 10 milligrams per kilogram (odds ratio 6.94, 95% confidence interval 4.85 to 9.92). In one trial of metrifonate compared with praziquantel, there was no difference demonstrated in a range of clinical outcomes including cessation of haematuria and proteinuria. Both drugs improved nutritional status and physical fitness. REVIEWER'S CONCLUSIONS: Praziquantel (single dose) appears to be more effective than metrifonate (split dose) in terms of parasitological cure of Schistosomiasis haematobium, but the reinfection rate is high with both drugs.

Anthelmintics↗
PubMed2000

School and neuropsychological performance of evacuated children in Kyiv 11 years after the Chornobyl disaster.

This paper examines the cognitive and neuropsychological functioning of children who were in utero to age 15 months at the time of the Chornobyl disaster and were evacuated to Kyiv from the 30-kilometer zone surrounding the plant. Specifically, we compared 300 evacuee children at ages 10-12 with 300 non-evacuee Kyiv classmates on objective and subjective measures of attention, memory, and school performance. The evacuee children were not significantly different from their classmates on the objective measures (grades; Symbolic Relations subtest of the Detroit Test; forms 1 and 2 of the Visual Search and Attention Test; Benton Form A; Trails A; Underline the Words Test) or on most of the subjective measures (the attention subscale of the Child Behavior Checklist completed by mothers; the attention items of the Iowa Conners Teacher's Rating Scale; mother and child perceptions of school performance). The one exception was that 31.3% of evacuee mothers compared to 7.4% of classmate mothers indicated that their child had a memory problem. However, this subjective measure of memory problems was not significantly related to neuropsychological or school performance. No significant differences were found in comparisons of evacuees and classmates who were in utero at the time of the explosion, children from Pripyat vs. other villages in the 30-kilometer zone, and children manifesting greater generalized anxiety. For both groups, children with greater Chornobyl-focused anxiety performed significantly worse than children with less Chornobyl-focused anxiety on measures of attention. The results thus fail to confirm two previous reports that relatively more children from areas contaminated by radiation had cognitive deficits compared to controls. Possible reasons for the differences in findings among the studies are discussed.

Achievement↗
PubMed1986

Auditory brain stem responses in the mentally retarded: audiometric correlates.

In previous reports we have suggested that the auditory brain-stem responses (ABRs) of adults with Down's syndrome exhibit two abnormalities unique to that population: a shortened central conduction time and an insensitivity of peak latencies to increases in stimulation rate. The current experiment assessed the possibility that these abnormalities were caused by hearing deficit rather than central auditory dysfunction. The ABRs of a group of adults with Down's syndrome were compared with those of a group of non-Down retarded and a control group of nonretarded adults. An audiometric examination consisting of pure-tone audiograms, tympanometry, and acoustic reflexes was given to all the retarded subjects. The incidence of serious hearing deficit in the Down's syndrome group was 73% compared to 22% in the non-Down retarded. Regardless of hearing status, the central conduction times in the Down group were shorter than in either of the other groups. The abnormal response to stimulation rate, however, was found to reflect high-frequency hearing loss and not central auditory dysfunction. The data suggest that a battery of objective tests including tympanometry, acoustic reflexes, and selected ABR measures may be useful in identifying hearing deficit in both Down-syndrome and non-Down retarded individuals.

Acoustic Impedance Tests↗
PubMed1983

Binaural interaction in auditory brainstem responses of mentally retarded and nonretarded individuals.

The short-latency auditory brainstem responses of institutionalized mentally retarded individuals (Down syndrome and unknown etiology) and nonretarded control persons were recorded. The results showed that retarded individuals differed in the clarity of initial auditory brainstem response waves (I and II). Down syndrome individuals had significantly smaller auditory brainstem response amplitudes (Waves II and III) when compared with retarded individuals of unknown etiology. Down syndrome individuals also had significantly shorter latencies (Waves III and V) and shorter interwave conduction times (III-I and V-I) when compared with retarded individuals of unknown etiology. Retarded individuals did not differ from control subjects when amplitudes of binaural auditory brainstem responses were compared to the computer summation of such responses evoked by left and right ear stimulation; however, there was evidence for a general binaural interaction effect.

Adolescent↗
PubMed1983

Effects of chronic administration of mestranol on alpha and beta adrenergic responsiveness in female rats.

Several alpha and beta adrenergic responses were studied in female rats after treatment with a low dose of the synthetic estrogen, mestranol (15 micrograms i.p. biweekly), for 4 to 6 weeks and compared with untreated controls. The response of blood pressure to exogenously administered norepinephrine was measured in conscious rats by means of an indwelling catheter in the femoral artery. Basal systolic blood pressure was not different between control and treated groups, or was any difference observed in peak systolic pressure after acute i.v. administration of l-norepinephrine in concentrations of 0.0625, 0.125, 0.250 and 0.625 micrograms. In contrast, the half-time of the blood pressure response was significantly prolonged after administration of the various concentrations of norepinephrine to mestranol-treated rats. The half-time of the pressor response observed in control animals administered 0.625 micrograms of norepinephrine was elicited in mestranol-treated animals by only 0.250 micrograms of norepinephrine. Analysis of the time course of the pressor response indicates that mestranol treatment altered the duration of the blood pressure increase without an apparent change in the onset of the pressor response. No differences between groups were observed in beta adrenergic responsiveness measured in terms of the isoproterenol-induced increase in either heart rate (beta-1 response) or water intake (beta-2 response). Finally, the contractile response of aortic rings from mestranol-treated rats to both l-norepinephrine (10(-9) to 10(-5) M) and l-phenylephrine (10(-8) to 10(-4) M) was significantly less than that of aortic rings from control rats. These data indicate, therefore, that in vivo cardiovascular responsiveness to norepinephrine does not reflect the attenuated vascular reactivity of isolated aortic rings. Insofar as the dominant feature of the in vivo adrenergic response appears to be prolongation of pressor action, the present study suggests that processes involved in the inactivation of circulating norepinephrine may be altered by chronic treatment with a low-dose of mestranol.

Animals↗
PubMed1980

Auditory brain stem response abnormalities in severely and profoundly retarded adults.

The auditory brain stem evoked responses (ABRs) of two groups of retarded adults (Down's syndrome and retarded of unknown etiology) were compared with those of a group of non-retarded control subjects as a function of changes in stimulus repetition rate and stimulus intensity. The absence of ABRs at the highest stimulus intensity suggested profound hearing deficits in one or both ears of 4 Down's syndrome and 2 unknown-etiology subjects. Other abnormalities were noted in particular individuals of each group of retarded. In addition, the ABRs of the Down's group as a whole showed a significant pattern of abnormalities. The intervals between peaks I and II and III and IV were shorter than normal white the IV--V interval was prolonged. Wave V also showed abnormally small latency increases at fast click rates. The ABRs of the unknown-etiology group showed a shortened III--IV interval and a prolongation of the IV--V interval, but were otherwise not significantly different from the normal controls. These data suggest a high incidence of hearing loss in both diagnostic categories studies, and abnormal functioning of the auditory brain stem pathway in the Down's syndrome group as a whole.

Acoustic Stimulation↗
PubMed1975

Second-order schedules: discrimination of components.

Pigeons were exposed to a series of second-order schedules in which the completion of a fixed number of fixed-interval components produced food. In Experiment 1, brief (2 sec) stimulus presentations occurred as each fixed-interval component was completed. During the brief-stimulus presentation terminating the last fixed-interval component, a response was required on a second key, the brief-stimulus key, to produce food. Responses on the brief-stimulus key before the last brief-stimulus presentation had no scheduled consequences, but served as a measure of the extent to which the final component was discriminated from preceding components. Whether there were one, two, four, or eight fixed-interval components, responses on the brief-stimulus key occurred during virtually every brief-stimulus presentation. In Experiment 2, an attempt was made to punish unnecessary responses on the brief-stimulus key, i.e., responses on the brief-stimulus key that occurred before the last component. None of the pigeons learned to withhold these responses, even though they produced a 15-sec timeout and loss of primary reinforcement. In Experiment 3, different key colors were associated with each component of a second-order schedule (a chain schedule). In contrast to Experiment 1, brief-stimulus key responses were confined to the last component. It was concluded that pigeons do not discriminate well between components of second-order schedules unless a unique exteroceptive cue is provided for each component. The relative discriminability of the components may account for the observed differences in initial-component response rates between comparable brief-stimulus, tandem, and chain schedules.

Journal Article↗
PubMed1972

Choice behavior and the accessibility of the reinforcer.

In Experiment 1, matching of relative response rates to relative rates of reinforcement was obtained in concurrent variable-interval schedules when the absolute values of the two concurrent variable-interval schedules varied from 6 sec and 12 sec to 600 sec and 1200 sec. Increases in the duration of the changeover delay, however, produced decreases in the relative response rates and, consequently, some deviation from matching. In Experiment 2, matching of relative response rates to the relative duration of the reinforcer failed to occur when the equal variable-interval schedules arranging access to the two different reinforcer durations (1.5 and 6 sec) were varied in size from concurrent variable-interval 10-sec schedules to concurrent variable-interval 600-sec schedules.

Journal Article↗
PubMed1971

A model for choice in simple concurrent and concurrent-chains schedules.

Pigeons' responses in the presence of two concurrently available (initial-link) stimuli produced one of two different (terminal-link) stimuli. Entrance into the mutually exclusive terminal links was arranged by different and independent variable-interval schedules for each key, while responses during the mutually exclusive terminal-link stimuli produced a single food reinforcement according to indentical and independent variable-interval schedules. The pigeons emitted more initial-link responses on the key with the shorter average interreinforcement interval in the initial link. This difference in initial-link response rates varied directly with the difference between the average inter-reinforcement intervals of the initial-link schedules and decreased when the initial-link schedule with the longer average interreinforcement interval was followed by several consecutive food reinforcements on the variable-interval schedule in the terminal link on that key. These results are incompatible with previous formulations of choice behavior with the concurrent-chains procedure. A modified formulation with a multiplier for the overall rate of primary reinforcement obtained on each key provides a better description of choice. In addition, the new formulation applies to behavior in simple (concurrent) choice situations, an advantage not achieved by previous formulations.

Journal Article↗
PubMedDate not supplied

Dysphagia management for progressive neurological conditions.

This article discusses some of the issues surrounding dysphagia management for patients with progressive neurological conditions. It is important that health professionals are aware of the available options and that they consider patients' wishes to meet their nutritional needs.

Cognition Disorders↗