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Biomedical subjects

M Finn

Publications and source records attributed to M Finn.

At least 19 recordsLinked to original sources
PubMed1998

Temporal measures of human finger tapping: effects of age.

A computerized finger-tapping test was used in which nonclinical subjects were asked to tap a telegraph key with their index finger as rapidly as possible during five 10-s trials. Comparisons were made between young (mean age = 18 years) and aged (mean age = 75 years) subjects. Consistent with previous findings, aged subjects performed significantly fewer taps than younger subjects. Computerized analysis of finger-tapping patterns in the present study allowed for the determination of novel temporal parameters of tapping responses. Response initiation time was defined as the time from the offset of one finger tap until the onset of the next finger tap. Aged subjects had significant and substantially longer response initiation times than younger subjects. Response duration times also were measured: this parameter was defined as the time from the onset of one finger tap until the offset of the same finger tap. Although the magnitude of the effect was small, aged subjects had significantly longer response duration times than younger subjects. Thus, although the deficit in response rate of a voluntary repetitive response in aged subjects was largely due to impairments in response initiation times, the response duration also contributes to the overall deficit in responding. Using these methods it is possible that greater insight into aging or extrapyramidal motor disorders, such as parkinsonism, may be obtained; it is also possible that these data may be useful as a research tool to aid in drug development and evaluation.

Adolescent↗
PubMed1997

Effects of clozapine, thioridazine, risperidone and haloperidol on behavioral tests related to extrapyramidal motor function.

Evidence indicates that the antipsychotic drug clozapine has a low propensity for the induction of extrapyramidal motor symptoms, and also that clozapine has therapeutic effects in patients with idiopathic Parkinson's disease. Because tacrine-induced tremulous jaw movements in rats have been suggested as a possible model of extrapyramidal motor dysfunctions, including parkinsonian tremor, the present work was undertaken to investigate the effects of clozapine on tremulous jaw movements. Clozapine decreased tacrine-induced tremulous jaw movements in a dose-related manner, with an ED50 of approximately 3.3 mg/kg. In order to determine the relative potency of this effect compared to other behavioral effects of clozapine, suppression of lever pressing was also studied. Clozapine reduced lever pressing in a dose-related manner, with an ED50 of approximately 5.4 mg/kg. This indicates that clozapine suppressed jaw movements at or below the doses required for suppression of lever pressing. In contrast, the typical antipsychotic drug haloperidol failed to suppress tacrine-induced tremulous jaw movements in doses up to 1.0 mg/kg, which is about 11-fold higher than the ED50 for suppression of lever pressing with that drug. Thioridazine and risperidone also suppressed tremulous jaw movements in roughly the same dose range at which lever pressing was reduced. It is possible that the suppression of tacrine-induced tremulous jaw movements by clozapine in rats is related to the unique behavioral and motor effects of clozapine. The ratio of potencies of these effects (i.e., suppression of tremulous jaw movements versus suppression of lever pressing) could be used as a behavioral procedure for assessing clozapine-like activity in novel compounds.

Animals↗
PubMed1997

Involvement of pallidal and nigral GABA mechanisms in the generation of tremulous jaw movements in rats.

Four experiments were conducted to investigate the role of pallidal and nigral GABA in the generation of tremulous jaw movements in rats. In these experiments, tremulous jaw movements were induced by i.p. injections of the anticholinesterase tacrine (5.0 mg/kg). Previous work has shown that the tremulous jaw movements induced by cholinomimetics and dopamine depletion are dependent upon striatal mechanisms. Thus, the present study investigated potential striatal output pathways that could be involved in the generation of these movements. Because there are GABAergic projections from neostriatum to entopeduncular nucleus (medial globus pallidus) and substantia nigra pars reticulata, the GABA agonist muscimol was injected directly into these structures to study the effects of GABA stimulation on tacrine-induced jaw movements. Injections of muscimol into the entopeduncular nucleus (25-100 ng) failed to have any significant effects on tacrine-induced vacuous jaw movements. However, injections of muscimol (12.5-50 ng) into the substantia nigra pars reticulata blocked the jaw movements induced by tacrine. In the third experiment, it was again demonstrated that 25.0 ng of muscimol injected directly into the substantia nigra pars reticulata blocked the jaw movements induced by tacrine; in addition, it was shown that injections of this dose 2.0 mm dorsal to the substantia nigra pars reticulata failed to affect tacrine-induced tremulous jaw movements. It was shown in the fourth experiment that injections of muscimol into a more medial portion of the substantia nigra pars reticulata also reduced tacrine-induced tremulous jaw movements. These results indicate that stimulation of GABA(A) receptors in substantia nigra pars reticulata can block tacrine-induced tremulous jaw movements. This finding is consistent with the notion that striatonigral GABA projections are involved in the generation of tremulous jaw movements. It is also possible that striatonigral GABA mechanisms are involved in human clinical phenomena such as parkinsonian tremor.

Animals↗
PubMed1997

Sensitization of the locomotor response to psychostimulants after repeated opiate exposure: role of the nucleus accumbens.

The following experiments were performed to ascertain the role of the nucleus accumbens in opiate-dopamine interactions using measures of locomotor activity. Three separate experiments were carried out. In Experiment 1, rats received systemic morphine (10 mg/kg IP) or saline (1 ml/kg IP) every other day for 5 days, followed by systemic amphetamine (1.5 mg/kg) 48 hours following the fifth injection. Animals in the morphine pretreatment group exhibited a sensitized locomotor response to amphetamine. In Experiment 2, animals received the same systemic pretreatment and were subsequently given intraaccumbens saline, amphetamine (2.5 micrograms/0.5 microliter) or cocaine (7 micrograms/0.5 microliter), each separated by 48 hours. Morphine-pretreated animals showed enhanced motor activity in response to intraaccumbens microinfusion of the psychostimulant drugs. Finally, in Experiment 3, multiple microinjections of morphine (0.5 microgram/0.5 microliter) directly into the nucleus accumbens resulted in a potentiated locomotor response to intraaccumbens amphetamine (2.5 micrograms/0.5 microliter). These data indicate that the nucleus accumbens may contribute to both the development and expression of opiate-stimulant cross-sensitization. The neural basis of this sensitization is hypothesized to be a common intracellular pathway affected by both classes of drugs, such as the cyclic adenosine monophosphate (AMP) system.

Amphetamine↗
PubMed1997

Microsporidia (Encephalitozoon cuniculi) in wild rabbits in Australia.

OBJECTIVE: To determine the prevalence of infection with Encephalitozoon cuniculi in wild rabbit populations in Western Australia, and to isolate the organism from seropositive rabbits. DESIGN: Serological screening of wild and clinically affected domestic rabbit populations. SAMPLE POPULATION: Eighty-one wild rabbits from south-western Western Australia and 29 laboratory rabbits. PROCEDURE: Indirect immunofluorescence antibody technique and in-vitro amplification of parasite isolates in fibroblast cultures. RESULTS: Of the 81 wild rabbits and 29 laboratory rabbits, 20 and 22 respectively, had antibodies to E cuniculi. E cuniculi from the urine of one seropositive laboratory rabbit and from brain and kidney tissues of eight and five seropositive laboratory and wild rabbits respectively were isolated in fibroblast cultures. CONCLUSION: E cuniculi infection has been shown for the first time to be prevalent in wild rabbits in Australia. Techniques have been developed for the isolation and culture of the causative agent. Comparative studies can now be undertaken to determine risk factors for clinical disease in domestic rabbits and the relationship among E cuniculi isolates from wild and domestic rabbits.

Animals↗
PubMed1996

Jealousy, general creativity, and coping with social frustration during the menstrual cycle.

Sensitivity to feelings of jealousy in women (n = 16) at three phases of their menstrual cycle differing in serum hormone concentrations (menses, preovulatory phase, midluteal phase) was investigated. Nonspecific electrodermal activity indicating sympathetic excitation was measured while subjects listened to stories and imagined situations inducing (i) nonsexual jealousy (the partner forms a deep emotional attachment to another woman), (ii) sexual jealousy (the partner has sexual intercourse with another woman), and (iii) no jealousy (social interaction lacking intense emotionality). Subjective ratings of the intensity of jealousy during both stories of jealousy were also assessed. In addition, changes in cognitive coping abilities, in general, and in the context of socially frustrating events, were assessed by tests of divergent thinking (creativity) and the Rosenzweig Picture Frustration Test. Frequency of nonspecific electrodermal reactions was generally enhanced during the preovulatory phase. This increase was particularly strong when the women listened to stories inducing nonsexual jealousy, i.e., a story characterized by cues of a complete loss of the partner's investment. Rated jealousy tended to be enhanced during the ovulatory phase, especially after the story of nonsexual jealousy. These changes in emotionality were paralleled by an improved divergent thinking performance and less aggressive coping with socially frustrating events around the time of ovulation.

Adaptation, Psychological↗
PubMed1995

Prototype instruments for endoscopic microsurgery: technical note.

The authors describe a concept of converting microsurgical instruments into endoscopes and demonstrate prototype devices. These instruments combine the benefits of microsurgery (multiple instruments, tactile feedback, bimanual manipulation, magnification) with those of endoscopy (minimally invasiveness, indirect line of vision).

Animals↗
PubMed1993

Screening for HIV and hepatitis B virus in Los Angeles County prenatal clinics: a demonstration project.

A project designed to pilot voluntary screening for HIV antibody and hepatitis B virus antigen (HBsAg) in women using Los Angeles County Department of Health Services prenatal clinics is described. The purpose of the study was to demonstrate that HIV testing could be integrated into an existing prenatal health care system with minimal disruption. In an 8-month period, 9,069 women entered the project; 76% accepted HIV antibody testing. The rate of HIV antibody seropositivity was 144 per 100,000 (10 per 6,943), and the rate of HBsAg seropositivity was 253 per 100,000 (23 per 9,103). No difference in test acceptance rates was found using a sign-off versus a sign-on HIV antibody consent form although potential confounders were not controlled. Only five of the eight HIV antibody-positive women (63%) and eight of the 20 HBsAg-positive women (40%) who were interviewed reported behaviors considered high risk for HIV or HBsAg infection.

Adult↗
PubMed1989

Erythropoietin.

Explore the source record for details and available documents.

Erythropoietin↗
PubMed1987

Effect of treatment with hydrochlorothiazide on the red cell Na,K-adenosine triphosphatase in men with hypertension.

We studied the effect of hydrochlorothiazide, 50 mg daily, on Na,K-adenosine triphosphatase (ATPase) activity in the red cells of 10 black men with hypertension. We also examined net sodium and potassium movement in sodium-loaded, potassium-depleted, red cells. Treatment with hydrochlorothiazide resulted in a significant increase in mean ouabain-sensitive ATPase activity (+/- SEM) from 118.4 +/- 14.6 to 158.1 +/- 15.3 nmol phosphate released per milligram of protein (P = 0.0004). Ouabain-resistant ATPase did not change. Net sodium extrusion rose significantly, from 1.62 +/- 0.27 to 2.32 +/- 0.33 mmol/L/hr (P = 0.0275). We postulate that the enhanced activity of the Na,K pump results from the volume contraction induced by the diuretic. This interpretation is consistent with the concept that the Na,K pump is inhibited in volume expansion and volume-expanded hypertension. The finding of enhanced pump activity in subjects given treatment with hydrochlorothiazide suggests a possible mechanism of the antihypertensive action of diuretic therapy.

Adult↗
PubMed1986

Amebic infections in asymptomatic homosexual men, lack of evidence of invasive disease.

A survey for enteric infections in 140 asymptomatic homosexual men who attended a community clinic revealed a high prevalence of infection with Entamoeba histolytica (27.1 per cent) and Giardia lamblia (15.7 per cent). In contrast, the prevalence of elevated indirect hemagglutination (IHA) titers (greater than or equal to 1:128), which indicate invasive amebiasis, was low (5.7 per cent). Our findings suggest that only a limited amount of invasive amebic disease is occurring in this group of homosexual men.

Adolescent↗