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Biomedical subjects

A Amin

Publications and source records attributed to A Amin.

At least 73 records · Page 4Linked to original sources
PubMed1991

Analgesic activity and respiratory effects of butorphanol in sheep.

The analgesic drug butorphanol tartrate has proved useful clinically in horses and dogs but its analgesic profile had not yet been investigated in sheep. This study was initiated to determine the thermal and mechanical antinociceptive activity of butorphanol (at the dose rates 0.05, 0.1 and 0.2 mg kg-1) in sheep. The drug produced significant analgesia in the thermal test system, the duration of which was dose related but no significant elevation in mechanical pressure thresholds could be detected. In a further set of experiments the dose rate was increased to 0.4 mg kg-1 and mechanical testing was repeated. There was still no clinically significant elevation in pressure thresholds. At a dose rate of 0.2 mg kg-1 the drug had no detectable effect on respiratory blood gas tensions. Behavioural changes were severe if a dose rate of 0.2 mg kg-1 was exceeded.

Analgesia↗
PubMed1991

Further studies on the antinociceptive activity and respiratory effects of buprenorphine in sheep.

The thermal and mechanical analgesic profile of buprenorphine at a dose rate of 1.5 micrograms/kg i.v. was investigated in five sheep. This dose produced significant analgesia for 40 min against the thermal stimulus, but no mechanical antinociception. A higher dose rate of 12 micrograms/kg also failed to produce antinociception to a mechanical stimulus. In addition, the effect of the drug (6 micrograms/kg) on respiratory gas tensions was determined and no significant changes were observed.

Analgesia↗
PubMed1991

Synapsis, strand scission, and strand exchange induced by the FLP recombinase: analysis with half-FRT sites.

We have used a previously described cross-linking assay and half-FRT site substrates to examine the requirements for synapsis, strand exchange, and strand scission. The cross-linking assay showed that the minimum functional FRT site needed for synapsis contains two inverted FLP-binding elements surrounding an 8-bp core. This indicates that four FLP molecules interact with four binding elements in a synaptic complex. The analysis using half-sites showed that the enzyme can catalyze efficient strand exchange between a half-site and the intact FRT site. The reaction occurred only if the half-site had at least 2 bp but no more than 4 bp of the adjoining core sequence. The exchange occurred exclusively at the regions of limited core homology between the respective half-site and the FRT site. The absence of strand exchange between an intact site and a half-site bearing regions of core nonhomology indicates that 1 bp of homology is not sufficient for the formation of stable recombinant structures. Qian et al. (X.-H. Qian, R. B. Inman, and M. M. Cox, J. Biol. Chem. 265:21779-21788, 1990) have recently shown that the FLP protein can catalyze the formation of dimeric, trimeric, and tetrameric complexes with half-FRT sites. We show that only half-sites that contained at least 2 bp of adjacent core could form stable dimer products and be cleaved by the enzyme. Stable dimers were formed between a noncleavable half-site and a cleavable half-site, suggesting that only a single cleavage event is needed for the formation of the dimer.

Base Composition↗
PubMed1991

Impairment of helper T-cell function and lymphokine-activated killer cytotoxicity following severe head injury.

Infection is a major complication of severe head injury, occurring in 50% to 75% of patients who survive to hospitalization. Previous investigations of immune activity following head injury have demonstrated suppression of helper T-cell activation. In this study, the in vitro production of interferon-gamma (INF-gamma), interleukin-1 (IL-1), and interleukin-2 (IL-2) was determined in 25 head-injured patients following incubation of peripheral blood lymphocytes (PBL's) with the lymphocyte mitogen phytohemagglutin (PHA). In order to elucidate the functional status of cellular cytotoxicity, lymphokine-activated killer (LAK) cell cytotoxicity assays were performed both prior to and following incubation of PBL's with IL-2 in five patients with severe head injury. The production of INF-gamma and IL-2 by PHA-stimulated PBL's was maximally depressed within 24 hours of injury (p less than 0.001 for INF-gamma, p = 0.035 for IL-2) and partially normalized within 21 days of injury. There was no change in the production of IL-1. When comparing the in vitro LAK cell cytotoxicity of PBL's from head-injured patients and normal subjects, there was a significant depression in LAK cell cytotoxicity both prior to (p = 0.010) and following (p less than 0.001) incubation of PBL's with IL-2. The results of this study indicate that IL-2 and INF-gamma production, normally required for inducing cell-mediated immunity, is suppressed following severe head injury. The failure of IL-2 to enhance LAK cell cytotoxicity suggest that factors other than decreased IL-2 production, such as inhibitory soluble mediators or suppressor lymphocytes, may be responsible for the reduction in cellular immune activity following severe head injury. These findings may have significant implications in designing clinical studies aimed at reducing the incidence of infection following severe head injury.

Adolescent↗
PubMed1987

Cotinine validation of self-reported smoking in commercially run community surveys.

A validation study was carried out on self-reported smoking for 1177 people in Sydney and Melbourne in 1983. Because of its long half life and the fact that smoking is its only source in body fluids, saliva cotinine was chosen as the validation measure. Cotinine levels above 250 nmol/l were used to classify people as smokers. The sensitivity of self-reported smoking was 92.6% and the specificity was 93.4%. There was some evidence that people in the process of changing their smoking status might be slow in updating their self-classification. The smoking prevalence estimate based on cotinine levels was found to be 1.7% lower than that for self-reported smoking status. The small proportion of false negatives and false positives suggests that commercially collected data banks can be valid sources of prevalence data. Correlation between cotinine level and reported cigarette consumption was not affected by sample volume, and was similar to that achieved for carbon monoxide and thiocyanate at a low 0.34. Regression analysis using self-reported cigarette consumption filter/non-filter cigarettes, and time since last cigarette as predictors, explained 13.6% of the variance in cotinine level.

Adolescent↗
PubMed1985

Retinal acuity evaluation with the potential acuity meter in glaucoma patients.

The potential acuity meter (PAM) is designed to evaluate retinal acuity in the presence of media opacities. We looked at patients with glaucoma but with clear media, and compared best corrected visual acuity with PAM results to see if they produced comparable results. Sixty eyes in 38 glaucoma patients and 20 eyes in 10 normal ocular patients were evaluated. Our results indicate that PAM visual acuity is a reliable indicator of Snellen visual acuity in normal eyes, in eyes with mild to moderate glaucomatous damage, and when PAM visual acuity measurements were better than 20/60. However, when visual field loss is severe and when PAM visual acuity readings were worse than 20/60, the correspondence between these and Snellen visual acuity was erratic. Poor PAM results will not correlate with postoperative visual acuity in patients with advanced glaucoma and cataracts.

Glaucoma↗
PubMed1981

Lack of effect of pulsed ultrasound on the mammalian EEG.

Anesthetized rhesus monkeys and rabbits were exposed to pulsed ultrasound, from a 1.8 cm diameter transducer placed against the head. Each ultrasonic exposure lasted 4 min; it consisted of a series of 1-2 mu sec pulses, with a frequency spectrum broadly centered about the transducer resonant frequency of 1.5 MHz, repeated at a rate of 950 Hz. The time averaged ultrasonics power was 12.6 mW, with an estimated peak power of ca. 15 watts. No changes were observed in the EEG or its power spectrum during or immediately after the exposure. This contrasts to a previous report of significant changes in the EEG of squirrel monkeys during comparable exposures to pulsed ultrasound. Analysis of the earlier reported results suggests that some of the "effects" were due to aliasing artifacts.

Anesthesia↗
PubMed1978

Further results of serological examination of domestic animals for leptospirosis in Afghanistan.

The authors examined serologically 329 specimens of domestic animals from 8 provinces of Afghanistan for the incidence of leptospirosis. They detected in 15.8% of the animals examined antibodies against Leptospira in titres of 1 : 800 and higher: in 6.4% with serotypes of the serogroup Hebdomadis, 5.5%--Tarassovi, 2.7%--Grippotyphosa, 2.4%--Pomona, 2.1% Javanica, 1.5%--Icterohaemorrhagiae, 0.6% each--Canicola, Ballum, Bataviae, 0.3%--Pyrogenes. Positivity was highest in the buffalo--55.0%, camel--10 of the 18 animals examined, and cattle--25.5%. It was considerably lower in sheep--2.3% and goat--3.2%; also positive was one of the 6 zebus examined.

Afghanistan↗