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Biomedical subjects

E A Jackson

Publications and source records attributed to E A Jackson.

At least 55 records · Page 3Linked to original sources
PubMed1985

Effects of serotonergic activity in nucleus accumbens septi on drug-induced circling.

The effects of injections of 5-hydroxytryptamine (5-HT) into the nucleus accumbens and lesions of the nucleus accumbens induced by 5,7-dihydroxytryptamine (5,7-DHT) on drug-induced circling were investigated in rats with unilateral nigrostriatal lesions induced by 6-hydroxydopamine (6-OHDA). Injections of 5-HT (60-120 micrograms in 1 microliter; 1 microliter/min) into the nucleus accumbens caused a significant decrease in the circling response to 5.0 mg/kg of d-amphetamine (s.c.). The distribution of radioactivity after intracerebral injections of [3H]5-HT using these parameters showed that although much of the injected material was retained in the nucleus accumbens there was also considerable spread to the frontal cortex. However, in further behavioural experiments, using an injection procedure (0.5 microliter; 0.11 microliter/min) which caused much greater retention of injected material in the nucleus accumbens, with minimal spread to the frontal cortex, the ability of 5-HT injected into the accumbens to block amphetamine-induced circling was not diminished. Moreover, injections of 5-HT into the frontal cortex did not have any effect on amphetamine-induced circling. Lesions of the nucleus accumbens induced by 5,7-DHT caused a significant enhancement of the contralateral circling response to 1.0 mg/kg of apomorphine and a similar but non-significant tendency to increase the circling responses to several other doses of apomorphine and amphetamine. The results provide evidence that serotonergic mechanisms in the nucleus accumbens inhibit circling behaviour generated by unilateral activation of nigrostriatal dopaminergic mechanisms.

5,7-Dihydroxytryptamine↗
PubMed1985

Family practice residents' prescribing patterns.

Prescription patterns of physicians in a family practice residency office were analyzed retrospectively from the following perspectives: frequency of prescribing for individual drugs and drug categories; effect of the level of postgraduate training on prescribing patterns; and effect of patient payment systems (Medicare-Medicaid, self-pay, third-party insurance) on the number of prescriptions. Antibiotics, antihistamine-decongestants, and antihypertensive medications were the most commonly prescribed medications. Psychotropic medications were used infrequently. An average of 0.70 prescriptions was issued on each office visit. Per office visit, first-year residents averaged 0.59 prescriptions, second-year residents averaged 0.69 prescriptions, third-year residents averaged 0.72 prescriptions, and the faculty averaged 0.98 prescriptions. Patients on Medicare-Medicaid averaged 0.78 prescriptions per office visit, self-pay patients averaged 0.25 prescriptions per visit, and patients with third-party insurance averaged 1.49 prescriptions per visit. The differences in the prescription rates between each payment group were significant.

Connecticut↗
PubMed1984

Effects of ribavirin on red blood cells.

Man and rhesus monkey may develop anemia during treatment with the broad-spectrum antiviral ribavirin (1-beta-D-ribofuranosyl-1,2,4-triazole-3-carboxamide). To assess whether the anemia is due to decreased production of erythrocytes, increased destruction, or a combination of both factors, the transport of ribavirin into erythrocytes and the drug's effect on the osmotic fragility, deformability, and half-life of erythrocytes were evaluated. The rate of uptake of ribavirin by erythrocytes was species and concentration dependent. Monkey cells accumulated the largest concentration of drug followed by human and rat cells. Monkey and human red cells, pretreated in vitro with ribavirin, retained 77 and 45% of the drug, respectively, when reincubated for 2 hr in drug-free medium. Rat red cells retained only 20% of their initial ribavirin content. Neither osmotic fragility nor deformability was altered by exposure of red cells to ribavirin in vitro. The half-life of 1,3-[3H]diisopropyl fluorophosphate (DFP)-labeled erythrocytes was measured in rhesus monkeys treated intramuscularly (im) for 10 days with either 15 or 60 mg/kg of ribavirin. A dose-related decrease in red cell survival was observed from Day 0 to 28. Thereafter, red cell half-lives were comparable to control values. These data indicate that ribavirin at a dose as low as 15 mg/kg decreases the half-life of red cells. This effect was reversible upon discontinuation of the drug. At 60 mg/kg, ribavirin also inhibited the release of red cells from the bone marrow. Termination of treatment was followed by release of red cells from the bone marrow as indicated by a drop in the specific activity of [3H]DFP-labeled red cells and marked reticulocytosis. No inhibition of red cell release from the bone marrow was seen in the low-dose group. These data suggest that ribavirin can decrease red cell survival as well as inhibit red cell release from the bone marrow. Both effects appear fully reversible when treatment is withdrawn.

Animals↗
PubMed1984

Effects of intranigral injections of dopamine agonists and antagonists, glycine, muscimol and N-methyl-D,L-aspartate on locomotor activity.

Previously it has been shown that bilateral intranigral injections of dopamine into rats pretreated with a monoamine oxidase inhibitor induced prolonged stimulation of locomotor activity, while bilateral intranigral injections of haloperidol reduced the locomotor stimulation evoked by systemic amphetamine. In the present studies, the role of the substantia nigra in locomotor activity was further investigated using a variety of dopaminergic and other agonists and neuroleptics. Ergometrine, epinine, (+/-)-2-amino-6,7-dihydroxy-1,2,3,4-tetrahydronapthalene hydrobromide (ADTN), 1,2,3,4-tetrahydro-6,7,-dihydroxyisoquinoline hydrochloride (THIQ), muscimol and glycine elicited locomotor activity when injected into the substantia nigra pars reticulata bilaterally. Additionally the non-dopaminergic agonists also elicited a degree of stereotyped behavior. Locomotor activity induced by intranigral ergometrine was blocked by systemic haloperidol but was not affected by intranigral haloperidol. Locomotor activity elicited by systemic amphetamine was blocked by bilateral intranigral alpha-flupenthixol, but that elicited by bilateral intra-accumbens ergometrine was not affected by alpha-flupenthixol or haloperidol injected into the substantia nigra pars reticulata bilaterally. The results provide further evidence that alterations of neurotransmission in the substantia nigra exert effects on locomotor activity.

Amphetamine↗
PubMed1984

Use of a sports medicine clinic in a family practice residency.

The experience of a pilot sports medicine clinic in affiliation with a family practice residency program is reviewed. The use of volunteer orthopedic staffing along with residents working in an acute sports medicine clinic in a community hospital proved to be a valuable addition to the orthopedic exposure during residency training. Seventy-eight patient contacts involving 93 injuries were encountered over a seven-week period. Three injuries required hospitalization for further definitive care. The benefits derived suggest that a similar clinic setup in other residency training programs could enhance the required orthopedic rotation as well as give acute, responsible care to the injured athlete. Educationally the resident's role as the athlete's physician provided a clinical experience valuable to a primary care practice.

Athletic Injuries↗
PubMed1983

Role of nigral dopamine in amphetamine-induced locomotor activity.

Dopamine (100 micrograms) injected into the substantia nigra pars reticulata of rats pretreated with the monoamine oxidase inhibitor, pargyline, resulted in a stimulation of locomotor activity. Bilateral injection of the dopamine antagonist haloperidol (5 micrograms) into the substantia nigra pars reticulata resulted in a reduction of the locomotor activity evoked by a low dose of amphetamine (1.25 mg/kg s.c.). These results suggest that the release of dopamine from nigral dendrites is involved in amphetamine-induced locomotor activity.

Amphetamine↗
PubMed1983

Behavioral activity of some novel aporphines in rats with 6-hydroxydopamine lesions of caudate or nucleus accumbens.

The behavioral actions of some novel aporphines have been examined in rats with selective unilateral 6-hydroxydopamine (6OHDA)-induced destruction of nigrostriatal dopaminergic neurons, and in rats with bilateral 6OHDA-induced destruction of mesolimbic dopaminergic neurons. Dopaminomimetics such as apomorphine (APO) in these animal models elicit circling behavior and locomotor activity respectively. In animals with unilateral nigrostriatal lesions (-)-2,10,11-trihydroxy-N-n-propylnoraporphine (TNPA) and (-)-10,11-methylenedioxy-N-n-propylnoraporphine (MDO-NPA) elicited weak, but prolonged, contraversive circling, whereas (-)-2,10,11-trihydroxyaporphine (2-OH.APO) was inactive. In animals with bilateral destruction of mesolimbic dopaminergic neurons TNPA and MDO-NPA elicited a strong stimulation of locomotor activity, while 2-OH.APO was inactive. The results suggest that TNPA and MDO-NPA, but not 2-OH.APO, exert central dopaminomimetic effects in vivo. The results are also consistent with previous data indicating that N-propyl substitution of aporphines causes a relative enhancement of activity in animal models which emphasise effects at mesolimbic rather than striatal dopaminergic receptors.

Animals↗
PubMed1983

Nigral dopaminergic mechanisms in drug-induced circling.

Unilateral injections of dopamine into the substantia nigra pars reticulata of pargyline-pretreated rats caused a prolonged, contralateral circling, similar in magnitude to that elicited by the injection of the same amount of dopamine intrastriatally. Contralateral circling was also elicited by the unilateral intranigral injection of amphetamine (after pargyline pretreatment), or by the dopamine agonists ergometrine and SKF 38393. In contrast, bilateral intranigral injection of the dopamine antagonist haloperidol greatly reduced the amphetamine-induced circling of rats with unilateral 6-hydroxydopamine-induced nigrostriatal lesions. These results support the hypothesis that dopaminergic mechanisms in the substantia nigra are involved in motor behavior.

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗
PubMed1977

Availability of insulin from parenteral nutrient solutions.

The effect of the following variables on insulin loss from total parenteral nutrient solutions was examined: (1) time of infusion sample; (2) insulin concentration; (3) amino acid or polypeptide source; (4) electrolytes and vitamins; (5) inline filters; (6) glass and polyvinyl chloride (PVC) infusion containers; and (7) human albumin. I125-tagged insulin was added to various parenteral nutrient solutions in liter containers. These solutions were prepared and drained to simulate actual clinical use. The drained solutions were collected and measured for radioactivity, and the percent of insulin remaining in the infusion container was calculated. Basic solutions of amino acids and protein hydrolysates in dextrose with 30 units of insulin failed to deliver approximately 44 to 47% of the added insulin. Varying the concentration of insulin had a small but statistically significant effect on the degree of insulin loss. The use of inline filters and PVC bags caused an even greater loss of insulin. The addition of albumin or electrolytes and vitamins decreased the insulin loss.

Absorption↗
PubMed1976

Urethral syndrome in women.

The pathological changes in the female urethra, para-urethral glands, and bladder neck, which manifest clinically as urethral syndrome, produce radiological signs which are recognizable but for which the authors have not found previous reports. The radiographic manifestations of this disease are clearly demonstrated by excretory urography. These changes are shown to correlate closely with the findings of cystography.

Adolescent↗
PubMedDate not supplied

The Talking Sex Project: descriptions of the study population and correlates of sexual practices at baseline.

The Talking Sex Project is an HIV risk reduction education project for gay and bisexual men. It was developed to evaluate two types of small discussion groups using a randomized control study design. This paper reports on the baseline measures of knowledge, attitudes and sexual practices. The 612 subjects had a mean age of 32 years, were all English speaking and were relatively highly educated. Bivariate analyses found that younger men, those in a relationship, those reporting bisexual activity and those with higher levels of substance use were significantly more likely to have unprotected anal intercourse. While overall knowledge was not associated with sexual behaviour, a significant relationship was found with knowledge of risk of anal sex. Attitudes, in particular, the belief in the efficacy of condoms and the enjoyment of safer sex were found to have the strongest associations with protected anal intercourse. The paper provides an understanding of some of the factors which may be important to behaviour change and clues for the targeting of programs.

Adolescent↗