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Biomedical subjects

G Jackson

Publications and source records attributed to G Jackson.

At least 289 records · Page 16Linked to original sources
PubMed1985

Laboratory diagnosis of myocardial ischemia.

The evaluation of myocardial metabolic changes in ischemic heart disease remains centered on the coronary sinus pacing and sampling techniques established over the last 25 years. Lactate remains the marker of choice for most institutions, though centers with more sophisticated laboratories will always be trying to improve on the sensitivity and specificity for ischemia, perhaps using ATP catabolites and nucleotides and measuring coronary sinus flow. The diagnostic value of lactate changes is limited and probably not superior to a well-conducted 12-lead treadmill exercise electrocardiogram test, but it does provide an objective marker for reliable further study and evaluation of interventions. It is almost certainly in the research context that metabolic studies have their place--evaluating drugs, surgery, or angioplasty and perhaps shedding light on obscure entities, such as chest pain with normal coronary arteries and cardiomyopathies. Attention to detail and simplicity of study are more likely to lead to valuable results rather than concentrating on the complexities. Each laboratory should establish the reproducibility of its results before commencing any procedures.

Adrenergic beta-Antagonists↗
PubMed1985

Isosorbide-5-mononitrate--effective monotherapy in chronic stable angina.

Isosorbide-5-mononitrate (ISMN) is not subject to first-pass metabolism and has more predictable blood concentrations than isosorbide dinitrate. In order to evaluate its efficacy as monotherapy in patients with chronic stable angina, 14 patients were studied. All had angiographically proven coronary artery disease and were limited by angina on a treadmill exercise test. After a 2-week placebo period ISMN was administered in a single-blind fashion with the dosage being titrated at 2-week intervals. The dosage increments were 20 mg once daily, 20 mg twice daily, 40 mg once daily and 40 mg twice daily. Patients were assessed subjectively by anginal attack rate and glyceryl trinitrate (GTN) consumption and objectively by treadmill exercise testing at 12 hours post dosage. ISMN increased the exercise ability significantly on all dosage regimes. However, a significant reduction in ST depression occurred only with the twice-daily regime. The increased exercise performance was associated with a significant decrease in anginal attack rate and GTN consumption from the 20 mg b.i.d. increment. ISMN is an effective antianginal agent with a more favourable profile in twice-daily dosage. Whilst no significant differences emerged between 20 mg and 40 mg twice daily, individual variation occurred, indicating a need for dosage flexibility.

Administration, Oral↗
PubMed1984

A study to compare the efficacy, plasma concentration profile and tolerability of conventional mexiletine and slow-release mexiletine.

In order to evaluate and compare slow-release mexiletine 360 mg 12 hourly and conventional mexiletine 200 mg 8 hourly, twelve patients with symptomatic ventricular arrhythmias have been studied. Ambulatory electrocardiographic monitoring was performed before treatment and at the end of two, two week long treatment periods during which slow-release mexiletine and conventional mexiletine were administered in random order. On the last day of each treatment period frequent blood samples for drug assay were collected during a dosage interval. Each formulation produced greater than 70% suppression of ventricular ectopic beats in 55% of patients. The variation between pre-dose and observed peak plasma concentration was 29.6% with slow-release mexiletine and 71.6% with mexiletine (P less than 0.01). The time from pre-dose to observed peak concentration was 4.0 h (+/- 1.6 SD) with slow-release mexiletine and 2.0 h (+/- 1.8 SD) with conventional mexiletine (P less than 0.05). Three patients were withdrawn from the study in the first treatment period because of central nervous system or gastric adverse effects. Overall, side-effects were marginally fewer on therapy with slow-release mexiletine. We conclude that, in the nearest equivalent dosage, the slow-release formulation is as effective as conventional mexiletine and at least as well tolerated. The fluctuations in plasma mexiletine concentration are less marked on the slow-release preparation despite the longer dosage interval, which allows effective oral therapy with a twice daily dosage.

Administration, Oral↗
PubMed1984

Diagnostic ultrasound in the assessment of patients with incompetent cervix.

Twenty-five pregnant women with suspected cervical incompetence were assessed by serial ultrasound. A dilating internal os was documented in one patient, incompetence was ruled out in two, and a 'slipping suture' was demonstrated in another; the remaining patients were subjected to cerclage on the basis of their history alone. Patients in whom the diagnosis of cervical incompetence is indefinite should have a diagnostic ultrasound scan to visualize the cervix for length, opening of the canal and integrity of the internal os. Selective ultrasonography may be beneficial in both the diagnosis and treatment of cervical incompetence.

Adult↗
PubMed1984

Acute myocarditis. Role of histological and virological examination in the diagnosis and assessment of immunosuppressive treatment.

Twelve patients, who presented with congestive cardiac failure after a recent influenza like illness, had a clinical diagnosis of acute myocarditis confirmed histologically after endomyocardial biopsy. Eight were under 30 years of age. Serological testing suggested a viral aetiology in six patients. Nine patients were treated with immunosuppressive drugs (prednisolone and azathioprine in seven, prednisolone alone in two). At two months, seven patients showed clinical and haemodynamic improvement (ejection fraction rose from 26.8 to 49% and left ventricular end diastolic pressure fell from 26.4 to 16.2 mm Hg) with biopsy evidence of healed myocarditis. In two, activity persisted. At six months' follow up only four of these patients had maintained their improvement. One patient relapsed after stopping treatment, subsequently improving on its reinstatement. Two patients developed severe interstitial myocardial fibrosis with gradual deterioration. Virology and myocardial histology were complementary in the diagnosis of acute myocarditis in these young patients, whose response to immunosuppressive treatment was variable. An apparent early response could not be clearly separated from variables in the natural history of the condition. Serial endomyocardial biopsies showed a progression to congestive cardiomyopathy in two patients. Multicentre controlled trials will be necessary to assess fully the role of immunosuppressive treatment in this condition.

Acute Disease↗
PubMed1984

Early exercise testing and elective coronary artery bypass surgery after uncomplicated myocardial infarction. Effect on morbidity and mortality.

One hundred and nineteen consecutive patients were studied prospectively after uncomplicated myocardial infarction by maximal exercise electrocardiography at two weeks and coronary angiography at six weeks. At angiography 87 patients had a stenosis greater than 70% in one major coronary artery supplying residual viable myocardium outside the infarction zone. In 82 (94%) of these the 12 lead maximal exercise electrocardiogram correctly identified these areas of ischaemic but viable myocardium. Based on ST criteria alone five patients had a false negative exercise electrocardiogram for additional disease. Nevertheless, three developed angina or a significant fall in systolic blood pressure or both at a low workload. On the basis of the anatomical lesions, symptoms, and the results of the European Coronary Surgery Study Group 55 patients were allocated for surgery. Of these, 54 underwent coronary artery bypass grafting within three months of myocardial infarction. One patient died perioperatively and another died after a reinfarction at four months while awaiting surgery. The remaining 53 were symptom free during a mean follow up period of 37 months. Sixty four patients received medical treatment. At angiography 32, 24, and eight patients had one, two, and three vessel coronary disease respectively. The exercise electrocardiogram correctly predicted the anatomy in 60 (94%), with two false positive and two false negative results for additional disease. The eight patients with three vessel disease treated medically had generalised inoperable disease, and at follow up three had died after a further infarction and five remained symptomatic with full medical treatment. Thus of those designated as at high risk and considered suitable for surgery the 37 month survival was 53 or 54 patients treated surgicall7y.

Adult↗
PubMed1983

Patients with angina with normal and near normal coronary arteries: clinical and psychosocial state 12 months after angiography.

The clinical and psychosocial states of 46 patients (26 men and 20 women) who had undergone cardiac catheterisation were examined prospectively. All of the patients had insignificant (less than 50%) coronary lesions and had been told that no limitation of activity was necessary. Twelve months after angiography 19 of the patients continued to complain of chest pain. Twenty one reported phobic symptoms, and 13 were found by standardised clinical interview to have psychiatric morbidity. This had been evident at the time of catheterisation in 28. Twenty three patients had evidence of unexplained breathlessness, 13 were taking psychotropic drugs, 29 were continuing to consult a doctor, and 11 were unable to work because of their symptoms. Patients initially assessed as having high levels of psychiatric morbidity and raised neuroticism scores were more likely to complain of chest pain one year after angiography. The 19 patients with persistent pain also had significantly higher levels of psychiatric and social morbidity at one year than the 27 patients whose chest pain had lessened during the follow up period. Those patients who fail to improve after being told that they have normal or nearly normal coronary arteries tend to be a chronically neurotic and socially maladjusted group in whom psychiatric disorder presents with predominantly somatic symptoms.

Adult↗
PubMed1983

Eradication of Mycoplasma bovis infection from a dairy herd in Great Britain.

Mycoplasma bovis infection was eradicated from a naturally infected dairy herd in Great Britain by a programme of identification, segregation and culling of infected animals. A series of group and whole milking herd tests was carried out over a period of 15 months, followed by a whole herd nasal swabbing. Cows were also sampled after calving and at drying off and bulk tanks were sampled at weekly intervals during the same period and for a further nine months. Fifty-nine cows were identified as excretors, the majority in group or herd tests, but five after calving and three at drying off. Eight of the original clinical cases were retained in the herd, after repeated negative test results. Bulk tank sampling was found to be extremely useful in detecting infection even down to one cow in a milking herd of 300. The value of milking hygiene and the indications for eradication are also discussed.

Animals↗
PubMed1983

Unexplained breathlessness and psychiatric morbidity in patients with normal and abnormal coronary arteries.

Of 99 patients with chest pain undergoing coronary arteriography, 31 had normal coronary arteries, 15 slight disease, and 53 significant coronary obstruction. 28 (61%) of the 46 with haemodynamically insignificant disease and 12 (23%) of the 53 with significant obstruction had psychiatric morbidity, assessed by standard interview. 37 patients had several respiratory symptoms and signs not attributable to organic disease, designated unexplained breathing disorder (UBD). UBD was found in 65% of the patients without and 13% of those with significant coronary disease; it was associated with psychiatric morbidity in the former but not in the latter group. Spirographic measurements of tidal volume and frequency were not helpful in detecting UBD but an end-tidal pCO2 below 30 mm Hg was highly suggestive. In the absence of significant coronary disease the associations of chest pain with psychiatric morbidity and UBD are striking. However, coronary disease and UBD are not mutually exclusive, and diagnostic difficulties can occur when they coexist.

Angina Pectoris↗
PubMed1983

The appropriate dosage regime for the transition from intravenous lignocaine to oral tocainide after acute myocardial infarction.

To define the appropriate regime for the transition from intravenous lignocaine to oral tocainide after uncomplicated acute myocardial infarction, 43 patients received lignocaine to steady state. Each patient then received a tocainide dosage schedule. Plasma concentration of lignocaine and tocainide was measured frequently until the third peak plasma tocainide level. Tocainide 400 mg 8 hourly starting 4 h before cessation of lignocaine and tocainide 400 mg 4 hourly starting at the end of the infusion produced therapeutic plasma tocainide concentration (3.5-9 mg/l) only after the second dose. Tocainide 600 mg 12 hourly starting 6 h before cessation of lignocaine and tocainide 600 mg 6 hourly starting at the end of the infusion quickly achieved therapeutic plasma tocainide concentration which declined to give subtherapeutic first dose troughs of 2.42 mg/l (+/- 0.28 SEM) and 2.79 mg/l (+/- 0.27 SEM) respectively. Consistently therapeutic plasma tocainide concentrations were achieved by both of these regimens after the second dose. The short plasma half-life of lignocaine which for these regimes was 3.71 h (+/- 0.25 SEM), resulted in subtherapeutic lignocaine concentrations before consistently therapeutic plasma tocainide concentrations had been achieved. On the basis of these results, the 600 mg 6 hourly tocainide dosage schedule was studied with cessation of lignocaine infusion either two or six h after the first tocainide dose. With the former regime only three of 5 patients had therapeutic lignocaine at the subtherapeutic tocainide trough.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1983

Failure of mean red cell volume to serve as a biologic marker for alcoholism in narcotic dependence. A randomized control trial.

Mean red cell volume, mean red cell hemoglobin, and mean red cell hemoglobin concentration were measured in a prospective, longitudinal, single-bind study of alcoholism and its treatment in 625 patients receiving methadone. Mean red cell volume and mean red cell hemoglobin were significantly elevated in alcoholic as compared with nonalcoholic patients (p less than 0.001), with a sensitivity of 40 and 51 percent, respectively. The ability of an elevated mean red cell volume and mean red cell hemoglobin to exclude active alcoholism (specificity) was 86 and 76 percent, respectively. Development of excessive consumption of alcohol during the course of the study was not associated with significant elevations over baseline values of either mean red cell volume or mean red cell hemoglobin. Similarly, the mean red cell volume and mean red cell hemoglobin in the small number of patients whose consumption of alcohol markedly decreased did not significantly change from baseline values. These findings suggest that although the specificity of mean red cell volume may be helpful in eliminating those persons who are not actively alcoholic, its sensitivity does not permit its use as a biologic marker for alcoholism. The inclusion of an elevated mean red cell volume as a major criterion for the diagnosis of alcoholism should be reconsidered.

Alcohol Drinking↗
PubMed1983

Traumatic right coronary artery--right atrial fistula.

Traumatic coronary artery fistulae and intracardiac shunts due to penetrating wounds of the heart are rare, with only 19 reported cases in the literature. The communication, which may involve one or both coronary arteries, is classified into two major types depending on whether the drainage is into the left or right heart. We report a right coronary artery (RCA) right atrial fistula (RA) secondary to shrapnel injury in 1944.

Angina Pectoris↗
PubMed1983

Diagnosis of acute aortic dissection by M-mode and cross-sectional echocardiography: a five-year experience.

During a five-year period, 26 cases of acute thoracic aortic dissection were studied by M-mode and cross-sectional echocardiography prior to cardiac catheterization and aortography. The diagnosis could be made non-invasively in 20 patients. Important information concerning the extent of the dissection, and the presence or absence of aortic regurgitation or a pericardial effusion could be obtained. Negative examinations were largely confined to cases where the distal thoracic aorta alone was involved. In a further 30 cases admitted to the coronary care unit during this period in which echocardiography was performed to rule out aortic dissection, two false-positive examinations led to aortography which demonstrated aortic dilatation and aortic regurgitation only. In the remaining 28 cases, echocardiographic examination was negative and none of these patients subsequently evidenced aortic dissection. Echocardiography using both M-mode and cross-sectional techniques is a rapid and highly effective method of making an early diagnosis of thoracic aortic dissection. Cross-sectional echocardiography is complementary to the M-mode technique, enhancing diagnostic accuracy by improving structural recognition in a condition where the normal anatomy is often severely distorted.

Acute Disease↗