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Biomedical subjects

J L Howard

Publications and source records attributed to J L Howard.

At least 73 records · Page 4Linked to original sources
PubMed1971

Effect of 6-hydroxydopamine on electrical self stimulation of the brain.

In rats, after a single intracisternal injection of 6-hydroxydopamine (6-OHDA) electrical self stimulation was reduced by approximately 50%. The concentrations of noradrenaline and dopamine in the brain were reduced by 83%. A second injection of 6-OHDA reduced the concentration of these amines to 7% of control values and virtually eliminated self stimulation.

Animals↗
PubMed1971

Effect of central catecholamine alterations on the hypothermic response to 6-hydroxydopamine in desipramine treated rats.

The hypothermia observed in rats kept in a cold environment after the intracisternal administration of 6-hydroxydopamine was enhanced by desipramine. Since pretreatment with 6-hydroxydopamine virtually eliminated the temperature fall in response to a subsequent dose of 6-hydroxydopamine, brain catecholamines were implicated in the response. Preferential reduction of brain noradrenaline antagonized the hypothermia after 6-hydroxydopamine in desipramine-treated rats to a greater extent than did the preferential reduction of dopamine. The results indicate the importance of noradrenergic fibres in this hypothermic response, but do not exclude an involvement of brain dopaminergic pathways.

Animals↗
PubMedDate not supplied

An audit of the effect of intravenous antibiotic treatment on spirometric measures of pulmonary function in cystic fibrosis.

BACKGROUND: This retrospective audit was undertaken to compare the efficacy of home intravenous (i.v.) antibiotic therapy, hospital i.v. antibiotic therapy and a combination of these 2 approaches, as determined by spirometric measures of lung function in cystic fibrosis (CF) patients, each with an acute respiratory exacerbation. METHODS: Pulmonary function, forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), forced vital capacity (FVC), forced expiratory flow rate between 25 per cent and 75 per cent of vital capacity (FEF25-75), and peak expiratory flow rate (PEFR) were compared between groups at the beginning and at the end of an IV antibiotic course. RESULTS: Treatment of exacerbations resulted in a significant improvement (p < 0.05) in lung function irrespective of where patients were treated. The percentage improvement in FEV1, FVC, and FEF25-75, were significantly greater in patients treated in hospital compared to those who had home i.v. treatment (p < 0.05). CONCLUSION: Hospital i.v. antibiotic therapy resulted in greater improvements in FEV1, FVC and FEF25-75 than home i.v. antibiotic therapy in CF patients with an acute respiratory infection.

Adolescent↗
PubMedDate not supplied

Classical aversive conditioning of heart rate in curarized rats at different blood gas levels.

In an effort to examine whether normal blood gas tensions were essential for conditioning, paralyzed rats received a classical aversive heart rate (HR) conditioning session while respirated at different peak expired CO2 values. After the session, arterial blood was drawn for analysis. That peak expired CO2 was effective in manipulating PCO2 was indicated by a significant correlation (r=0.594, df=17, P less than 0.05). In addition, only rats with blood gas values similar to those of anesthetized controls displayed a discriminated HR CR. These animals also had lower baseline HRs and greater HR variability. Further, 7 of the 9 rats with normal blood gas values were respirated at peak expired CO2 values from 5.0-5.1 per cent, and no animal ventilated within this range displayed abnormal values. These findings suggest that previous difficulties in obtaining calssical and operant conditioning in paralyzed animals may, in part, be attributable to inadequate ventilation.

Animals↗