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Biomedical subjects

R Knight

Publications and source records attributed to R Knight.

At least 37 records · Page 2Linked to original sources
PubMed1989

Reduction of hyperthermic ischemic acidosis by a conditioning event in cats.

We investigated the effects of multiple episodes of cerebral ischemia on intracellular brain pH using in vivo phosphorus-31 nuclear magnetic resonance spectroscopy. Four cats were subjected to two 16-minute episodes of complete global cerebral ischemia 6 hours apart; the second episode occurred under hyperthermic conditions (mean +/- SD body temperature 40.8 +/- 0.4 degrees C). Intracellular pH in these four cats was compared with that in nine cats subjected to a single 16-minute episode of complete global cerebral ischemia under hyperthermic conditions (mean +/- SD body temperature 40.6 +/- 0.2 degrees C). Intracellular pH during hyperthermic recirculation was significantly (p less than 0.03) greater in cats subjected to a previous ischemic event than that in cats subjected to only a single hyperthermic ischemic event. We speculate that the induction of heat shock proteins by an initial ischemic event may protect brain tissue from further ischemic insult.

Acidosis↗
PubMed1989

Creutzfeldt-Jakob disease.

Creutzfeldt-Jakob disease is a 'slow virus' illness usually presenting as a rapidly progressive dementia. Although rare, its laboratory and accidental transmission has given it great theoretical importance. However, the infective agent remains mysterious and it is not known how, or even whether, natural transmission occurs. Clinical diagnosis is difficult, treatment unfortunately unsuccessful and special precautions are necessary in dealing with potentially infectious material.

Chronic Disease↗
PubMed1989

A study of knowledge, attitudes and practices (KAP) of a rural community on malaria and the mosquito vector.

A study of malaria on the Kano Plain, Kisumu District, Western Kenya, was carried out between April and August, 1985. The study included a knowledge, attitudes and practices (K.A.P.) survey on malaria illness and the mosquito vector. Overall knowledge about malaria illness was found to be good. However, treatment and prevention practices of malaria were found to be poor. Knowledge of the mosquito and its relationship to malaria was found to be high. Knowledge of methods of prevention of mosquito bites was also found to be high but actual use of the methods was low. Knowledge of traditional methods of prevention of mosquito bites was also found to be high. Actual use was again found to be low.

Gastric Acid↗
PubMed1988

Creutzfeldt-Jakob disease in England and Wales, 1980-1984: a case-control study of potential risk factors.

An attempt was made to ascertain all cases of Creutzfeldt-Jakob disease occurring in England and Wales during the 5 year period 1980-1984. The mean annual mortality rate was 0.49/million; women were more frequently affected than men. The age-specific mortality rate reached a peak in the seventh decade. A case-control study involving 92 of the 122 definite and probable cases ascertained failed to confirm the reality of previously suspected aetiological agents in the environment. Although there was no confirmed instance of familial Creutzfeldt-Jakob disease in the case-control study, dementia in close relatives was significantly more common than in controls.

Adult↗
PubMed1988

Effect of mild hyperthermia on recovery of metabolic function after global cerebral ischemia in cats.

We investigated the effect of mild whole-body hyperthermia before and after 16 minutes of global cerebral ischemia on metabolic recovery during recirculation in cats using in vivo phosphorus-31 nuclear magnetic resonance spectroscopy. Hyperthermia (temperature 40.6 +/- 0.2 degrees C) was induced greater than or equal to 1 hour before ischemia and was maintained during 1.5-2 hours of recirculation in nine cats; four cats were subjected to hyperthermia without cerebral ischemia, six to hyperthermia during recirculation (after return of intracellular pH to preischemic values), and 14 to normothermic ischemia and recirculation. Our data indicate that preischemic hyperthermia results in an intracellular cerebral pH during recirculation significantly lower than that in normothermic cats. In hyperthermic cats beta-ATP and phosphocreatine (PCr) concentrations and the ratio of PCr to inorganic phosphate failed to return to preischemic levels during recirculation in contrast to normothermic cats. Hyperthermia without ischemia and hyperthermia during recirculation had no significant effect on intracellular pH. Thus, preischemic hyperthermia has a detrimental effect on metabolic recovery after transient global cerebral ischemia.

Acidosis↗
PubMed1986

A diurnal rhythm in proopiomelanocortin messenger ribonucleic acid that varies concomitantly with the content and secretion of beta-endorphin in the intermediate lobe of the rat pituitary.

The present study investigated whether diurnal variations in the secretion of alpha MSH and beta-endorphin from the intermediate lobe (IL) of the pituitary are associated with parallel changes in the synthesis of mRNA specifically encoding proopiomelanocortin (POMC). The results demonstrate that concomitant diurnal variations occur in both plasma and IL concentrations of immunoreactive beta-endorphin and alpha MSH. Plasma and IL peptide levels were relatively constant during daylight hours (0600-1800 h), but increased after the onset of darkness and reached maximal concentrations at 0200 h. To examine the possibility that this diurnal rhythm in the content and secretion of POMC-derived peptides resulted from diurnal changes in the biosynthesis of POMC, the concentration and rate of synthesis of POMC mRNA were examined. POMC mRNA levels were elevated during the dark period, reaching a maximum level at 0200 h that was 2-fold higher than that occurring during the light period. POMC mRNA synthesis, determined by measuring the number of RNA polymerase II complexes transcribing the POMC gene in isolated cell nuclei, also varied diurnally, with maximum transcription rates occurring at 1800 h, thus preceding maximal increases in POMC mRNA content and POMC peptide secretion by 8 h. Together, these data indicate that diurnal variations in the content and secretion of POMC-derived peptides are associated with parallel changes in POMC mRNA concentrations and are preceded by similar changes in POMC gene transcription.

Animals↗
PubMed1986

Ethological studies of depressed patients.

The use of ethological methods for characterising the non-verbal behaviour of depressed patients and quantifying change during treatment is described. Approximately 150 individual motor patterns--expressions, gestures and movements--have been defined and this element list provides the basis for encoding video-recordings of interactions. Data quality is controlled by inter- and intra-observer comparisons and by a split-screen technique which simultaneously displays a computer animation of a data file and the original video-recording. Two investigations of the characteristics of non-verbal behaviour in Depression are discussed. The first showed that the frequency and duration of many items of behaviour of depressed patients interviewed soon after admission to hospital differed significantly from matched controls. Recordings of an interview at an intermediate point in treatment showed a reduction in these differences and they had disappeared when examined shortly before discharge. The second study was of mothers suffering from Post Natal Depression who were interviewed once. This study provided evidence that quantification of non-verbal behaviour can distinguish between diagnostic subcategories and showed some of the fine detail of behaviour which can be revealed in this way.

Animals↗
PubMed1985

Effect of beta-blockers on psychomotor performance in normal volunteers.

The effects of beta-adrenergic receptor antagonists on psychometric tests including vehicle handling, choice reaction time, and kinetic visual acuity (KVA), are reviewed. The beta-blockers had little effect on the performance tests, with the unexplained but reproducible effect of enhanced KVA performance with atenolol. Although the beta-blockers had little effect on performance tests they were shown to have psychotropic effects in normal volunteers. The reasons for the conflicting evidence concerning the effect of these drugs on performance tests is discussed in relation to the present experiments and to variables that may influence response. It is concluded that one should use tests that are as independent as possible from potentially confounding variables. The use of evoked potentials in the electroencephalogram is one such test. A preliminary study is described in which the effects of beta-blockers were detected using visual evoked responses on the electroencephalogram.

Adolescent↗
PubMed1979

Long-term results after surgical correction of Ebstein's anomaly: report of two cases.

Two patients with Ebstein's anomaly had valve replacement with Starr-Edwards cloth-covered valves 11 and 8 years ago. They have been asymptomatic and very active despite the absence of anticoagulation. These cases provide some of the long-term results needed for proper evaluation of the different methods of operative treatment of Ebstein's anomaly.

Adolescent↗
PubMed1978

Enflurane anesthesia and changes of intracranial pressure.

Enflurane has been recommended by some as an ideal agent for use in neuroanesthesia. There is no statistically significant alteration of normal intracranial pressure with enflurane anesthesia. However, supporting a clinical impression, this study demonstrates in dogs that enflurane will significantly increase an already elevated intracranial pressure.

Animals↗