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Biomedical subjects

N Buchanan

Publications and source records attributed to N Buchanan.

At least 37 records · Page 2Linked to original sources
PubMed1994

Clonazepam withdrawal in 13 patients with active epilepsy and drug side effects.

We report the end result of clonazepam (CZP) withdrawal in 13 patients with significant side effects felt to be due to CZP. The present observations supplement the recent report in Seizure by Chataway et al., in proposing a safe CZP withdrawal rate of 0.2 mg/day. Eight of the patients had withdrawal seizures, five had withdrawal symptoms and four patients had no withdrawal problems at all. Ultimately all the patients came off CZP, mainly quite rapidly (3-30 days) with the initial side effects regressing totally in 11 patients.

Adolescent↗
PubMed1994

Vigabatrin use in 72 patients with drug-resistant epilepsy.

OBJECTIVE: To determine the efficacy of a new anti-epileptic medication vigabatrin in adults and children with drug-resistant epilepsy. DESIGN AND SETTING: An open, uncontrolled study in a tertiary referral clinic setting with vigabatrin used as add-on therapy. SUBJECTS: All persons with intractable epilepsy, predominantly with complex partial seizures, with or without secondary generalization. MAIN OUTCOME MEASURES: Outcome was assessed by the patient and physician in terms of reduction of seizure frequency and severity balanced against drug side effects. RESULTS: Of 72 patients studied, seven are seizure-free and a total of 41/72 (57%) continue to take vigabatrin as they are deriving benefit therefrom. The results were most striking in patients with complex partial seizures with, or without, secondary generalization (65.6 and 60.9% ongoing treatment, respectively). Most of the 31 patients who ceased taking vigabatrin did so due to a lack of effect, but 9/31 did so because of adverse events: behavioural change, increased seizure frequency and oedema. CONCLUSIONS: Vigabatrin has a definite role to play in the management of persons with intractable complex partial seizures where standard anti-epileptic therapy has failed to achieve control.

Adolescent↗
PubMed1994

Trypanosoma brucei: characterization of protein kinases that are capable of autophosphorylation in vitro.

Autophosphorylation by protein kinases has been implicated as an important control mechanism in signal transduction and growth regulatory pathways in mammalian cells. We have set out to investigate whether any such autophosphorylating protein kinase activities can be found in Trypanosoma brucei. In order to do this, we have developed a system for characterizing such protein kinase activities using an in vitro assay. This assay was carried out by fractionation of trypanosome lysates using isoelectric focusing gel electrophoresis followed by incubation of the gel in gamma 32P-labelled nucleotide triphosphate and subsequent autoradiography. We have identified two classes of autophosphorylating protein kinase activities. In the first class all were dependent on ATP as the phosphate donor substrate and were all found to have a molecular size of 60 kDa. Differences in the activity of these protein kinases were observed between the bloodstream and procyclic life-cycle stages. Furthermore, the addition of mammalian epidermal growth factor to bloodstream stage lysates stimulated an additional activity. The second class of autophosphorylating protein kinases utilized GTP as the phosphate donor and were all found to be 90 kDa in size. Stage-specific differences were also observed in the activity of these protein kinases.

Adenosine Triphosphate↗
PubMed1994

Analysis of a new genetic cross between two East African Trypanosoma brucei clones.

Two clones of East African Trypanosoma brucei, with distinct homozygous isoenzyme patterns for one of three enzymes examined, were cotransmitted through the tsetse fly vector Glossina morsitans centralis. Flies with mature infections were individually fed on mice and the subsequent bloodstream from populations analysed for the presence of hybrid trypanosomes by isoenzyme analysis. Several combinations have previously been detected using this approach (Schweizer, Tait & Jenni, 1988; Sternberg et al. 1989). Four clones were isolated from one of the hybrid-containing populations. They showed a hybrid phenotype, as would be expected for the F1 progeny in a diploid Mendelian system. The analysis of the progeny clones, using two gene probes which detect restriction fragment length polymorphisms between the two parental stocks, showed that alleles had segregated at each locus and given rise to three different non-parental combinations of alleles in the hybrid progeny. Characterization of the hybrid progeny clones by PFGE (pulsed field gradient gel electrophoresis) revealed that all progeny clones were recombinant for the intermediate size chromosomes. From the analysis of the segregation of the larger chromosomes, marked by PGK (phosphoglycerate kinase) and CP (cysteine protease) gene probes, it was inferred that the progeny clones did not result from a direct fusion of diploid cells. Results with the PGK probe fit into a classical system with meiosis and subsequent fusion of the nuclei to form diploid progeny. On the other hand, blots with the CP probe as well as some of the ethidium bromide stained PFGE gels revealed the existence of non-parental size chromosomes in some of the hybrid progeny. This phenomenon was observed previously (Gibson, 1989) and further investigation is required to elucidate the mechanism.

Africa, Eastern↗
PubMed1994

Increase in blood lactate during ramp exercise: comparison of continuous and threshold models.

Controversy persists regarding the mechanism underlying the lactate threshold. It has recently been argued that there is in fact no "threshold" and that blood lactate increases as a continuous function during exercise (Hughson J. Appl. Physiol. 62:1975-1981, 1987). In comparing continuous and threshold models, questions have been raised regarding the ramp rate, data sampling, and the mathematical models employed (Morton J. Appl. Physiol. 67:885-888, 1989). To address some of these concerns, we evaluated 61 subjects (mean age 45 +/- 15), who underwent maximal ramp treadmill tests with the ramp rate individualized such that test duration was approximately 10 min for each subject. The relationship between changes in blood lactate and oxygen uptake were evaluated using a modification of the log-log transformation model described by Beaver (J. Appl. Physiol. 59:1936-1940, 1985) and a continuous exponential plus constant model described by Hughson et al. (J. Appl. Physiol. 62:1975-1981, 1987). Model fitting, using mean squared error (MSE) and coefficient of determination (CD) for each method were as follows: [table: see text] The modified log-log model had a better fit as indicated by the lower MSE and higher CD, suggesting the change in lactate was better described by this model. However, the differences were so slight as to suggest: 1) a meaningful difference does not exist between the two; or 2) these methods may not be capable of detecting a difference, if one exists.

Adult↗
PubMed1993

Effects of sublingual nitroglycerin on the gas exchange response to exercise in stable angina pectoris.

To quantitate changes in gas exchange variables that occur after administration of sublingual nitroglycerin in patients with stable angina pectoris, a randomized double-blind 2-period crossover study was performed with continuous expired gas exchange analysis and progressive exercise using individualized ramp treadmill protocols. Significant reductions in minute ventilation and respiratory rate were observed at 5 minutes of exercise during nitroglycerin therapy. Gas exchange variables i.e., minute ventilation, carbon dioxide production and oxygen uptake were significantly increased at the onset of angina after nitroglycerin administration. When techniques for optimizing the assessment of cardiopulmonary function were used, significant improvements in gas exchange variables were demonstrated in stable angina pectoris after administration of sublingual nitroglycerin.

Administration, Sublingual↗
PubMed1993

Noncompliance with medication amongst persons attending a tertiary referral epilepsy clinic: implications, management and outcome.

The present report looks at the nature, management and outcome of episodes of noncompliance with antiepileptic medication in 42 patients attending a tertiary referral epilepsy clinic with noncompliance being ascertained by patient admission. The main causes of noncompliance were forgetfulness, a refusal to take medication and a patient perception that their epilepsy was not severe enough to warrant medication. Management consisted of individual patient discussion, frequently on recurrent occasions. As far as outcome was concerned, 20 patients had no further episodes of noncompliance during the period of follow-up, five came off medication altogether and remain seizure-free, three improved but have lapses and in nine patients it was not possible to effect any change. Overall, individual patient management was helpful and worthwhile.

Adolescent↗
PubMed1993

Pseudoseizures (non epileptic attack disorder)--clinical management and outcome in 50 patients.

The present report outlines the clinical management and outcome of 50 patients with pseudoseizures who, for practical reasons, are divided into acute and chronic groups. The former group, perhaps not surprisingly, fared better than the latter. Management consisted primarily of confrontation with the diagnosis with additional psychotherapy of various degrees of intensity. Overall, 46% of patients taking anticonvulsants either came off their medication or had it reduced. It was encouraging to observe that 76% of the 50 patients derived significant benefit for management with, on follow up, 80% of the acute group and 28% of the chronic group becoming seizure free and 34% of the latter group improving significantly. Early diagnosis and management are important in dealing with the problem of pseudoseizures and appear to produce a good outcome, associated, in general terms, with a less satisfactory outcome in those in whom the problem is chronic.

Adolescent↗
PubMed1993

Characterization of Megatrypanum trypanosomes from European Cervidae.

Megatrypanum trypanosomes have been isolated from a number of different European Cervidae, but on the basis of morphology it has not been possible to define the species to which these isolates belong. We isolated Trypanosoma (Megatrypanum) theileri from 10 cattle, and Megatrypanum trypanosomes from 11 fallow deer (Cervus dama), 9 red deer (Cervus elaphus), and 4 roe deer (Capreolus capreolus) by blood culture on a biphasic medium (NNN agar slopes). Trypanosomes were propagated in Schneider's Drosophila medium and characterized by isoenzyme analysis and molecular karyotyping. Isocitrate dehydrogenase and phosphoglucomutase were visualized after starch gel electrophoresis of trypanosome lysates. By cluster analysis of this data all isolates from deer were clearly separated from the T.(M.) theileri isolates from cattle. Isolates from roe deer were different not only from T. (M.) theileri but also from the other deer isolates. Isolates from fallow deer and red deer were grouped together. Thus, there are probably at least two different species of Megatrypanum trypanosomes in the three Cervidae. One parasitizing roe deer, the other, apparently less host specific species, infecting red deer and fallow deer. Separation of the chromosomes of Megatrypanum trypanosomes by pulsed-field gradient gel electrophoresis (PFGE) showed that each isolate contained a large number (> 18) of chromosomes ranging in size from 300 to > 2200 kb. The molecular karyotypes were similar for all isolates, although no isolate was identical to another.

Animals↗
PubMed1993

Local action transcutaneous flurbiprofen in the treatment of soft tissue rheumatism.

The objective of the present study was to establish the efficacy and tolerability of local action transcutaneous flurbiprofen (flurbiprofen LAT) in the treatment of soft tissue lesions. A randomized, double-blind, parallel-group placebo-controlled study was carried out in two hospital outpatient rheumatology clinics. One hundred and four patients aged 18-75 yr were randomized to receive a non-woven polyester-backed patch supporting a formulation containing 40 mg flurbiprofen 12-hourly over 14 days; or a non-medicated (but otherwise identical) control. Statistically significant differences in favour of the active preparation were seen at both days 7 (P = 0.02) and 14 (P = 0.009) for the investigator's overall opinion of severity of the condition, and at day 7 for the investigator's assessment of pain severity (P = 0.04 intention-to-treat; P = 0.052 N.S. eligible data). The need for further treatment in the form of steroid injections after the trial was greater in the controls (29/44, 66%) than in the flurbiprofen LAT group (17/46, 37%) (chi 2 = 7.54 on 1 d.o.f., P = 0.006). Plasma flurbiprofen levels in 11 patients ranged from 13.4 to 338.7 ng/ml (mean 116; median 57.9). Eight out of 53 (15%) patients receiving flurbiprofen LAT reported a total of 10 adverse events, compared with three out of 51 (6%) reporting seven events among controls. Patients found the patch convenient and soothing. We conclude that flurbiprofen LAT is an effective and acceptable treatment for soft tissue lesions, and should be considered as an alternative therapy to local steroid injection.

Administration, Cutaneous↗