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Biomedical subjects

A McKenzie

Publications and source records attributed to A McKenzie.

At least 73 records · Page 4Linked to original sources
PubMed1990

The incidence of antimonocyte alloantibodies. Evidence that prospective crossmatching is unnecessary.

Monocyte cytotoxic crossmatches were performed on the sera of all 164 patients on the Victorian transplant waiting list in order to determine the incidence of antimonocyte antibodies and to assess if prospective screening for these antibodies would be justified. Initially all current sera were screened without absorption by the cytotoxicity assay for the presence of antilymphocyte and antimonocyte reactivity against a panel of ten donors. Subsequently, a further 45 "peak"-reactive sera were screened against the same panel. Forty sera with monocyte specific reactivity were selected. MHC class I and class II antibodies were absorbed with pooled platelets and B lymphoblastoid lines, respectively. The absorbed sera were then screened against T cells, B cells, and monocytes of 38 donors for monocyte-specific antibodies. Seven sera from six recipients showed monocyte reactivity without T cell or B cell reactivity, with panel reactivity ranging from 3-29%. This gives an overall patient incidence of 3.6%, and when expressed as a percentage of consecutive crossmatches has a calculated incidence of 0.45%. This incidence is much lower than previously reported and would indicate that prospective crossmatching for antimonocyte antibodies would not be of benefit in this group of patients.

B-Lymphocytes↗
PubMed1988

Percutaneous extraction of retained common bile-duct stones via the T-tube track.

A total of 86 procedures were performed in 58 patients referred in the postoperative period, for percutaneous stone extraction through the T-tube track. In 43 patients, the stone or stones were extrahepatic, intrahepatic in nine, and both intrahepatic and extrahepatic in six patients. Of the 58 patients with residual bile-duct stone(s), 48 (83%) were treated successfully by percutaneous removal, seven (12%) had an endoscopic sphincterotomy following unsuccessful T-tube track extraction, one (2%) had a re-operation and two (3%) remain with residual stones. No major complications occurred in this series. In contrast to endoscopic sphincterotomy, percutaneous T-tube extraction of retained bile-duct stones is associated with no mortality and low morbidity and is advocated as the procedure of choice in the presence of a T-tube.

Adult↗
PubMed1986

Echocardiographic measurement of left ventricular hypertrophy in untreated essential hypertension.

The prevalence of left ventricular hypertrophy (LVH) in human essential hypertension is uncertain. Echocardiography was used to calculate left ventricular wall thickness (WT), relative wall thickness (t/r) and left ventricular mass (LVM) in 52 normal subjects, 30 patients with borderline hypertension and 33 untreated patients with essential hypertension. In 52 normal subjects WT was independent of age, sex, BSA, BP or habitual physical activity, but LVM was significantly related to BSA and age. After correction of LVM for age and BSA, 88% of 33 patients with untreated essential hypertension had LVM greater than predicted which identified a larger proportion of hypertensives with LVH than previous studies suggest. Wall thickness measurement alone also indicated that about 80% of newly diagnosed hypertensives have LVH.

Adolescent↗
PubMed1986

Properties of signals that determine the amplitude and direction of saccadic eye movements in monkeys.

Monkeys were trained to make saccades to briefly flashed targets. We presented the flash during smooth pursuit of another target, so that there was a smooth change in eye position after the flash. We could then determine whether the flash-evoked saccades compensated for the intervening smooth eye movements to point the eyes at the position of the flash in space. We defined the "retinal error" as the vector from the position of the eye at the time of the flash to the position of the target. We defined "spatial error" as the vector from the position of the eye at the time of the saccade to the position of the flashed target in space. The direction of the saccade (in polar coordinates) was more highly correlated with the direction of the retinal error than with the direction of the spatial error. Saccade amplitude was also better correlated with the amplitude of the retinal error. We obtained the same results whether the flash was presented during pursuit with the head fixed or during pursuit with combined eye-head movements. Statistical analysis demonstrated that the direction of the saccade was determined only by the retinal error in two of the three monkeys. In the third monkey saccade direction was determined primarily by retinal error but had a consistent bias toward spatial error. The bias can be attributed to this monkey's earlier practice in which the flashed target was reilluminated so he could ultimately make a saccade to the correct position in space. These data suggest that the saccade generator does not normally use nonvisual feedback about smooth changes in eye or gaze position. In two monkeys we also provided sequential target flashes during pursuit with the second flash timed so that it occurred just before the first saccade. As above, the first saccade was appropriate for the retinal error provided by the first flash. The second saccade compensated for the first and pointed the eyes at the position of the second target in space. We conclude, as others have before (12, 21), that the saccade generator receives feedback about its own output, saccades. Our results require revision of existing models of the neural network that generates saccades. We suggest two models that retain the use of internal feedback suggested by others. We favor a model that accounts for our data by assuming that internal feedback originates directly from the output of the saccade generator and reports only saccadic changes in eye position.

Animals↗
PubMed1986

Screening for antenatal and postnatal depressive symptoms in general practice using a microcomputer-delivered questionnaire.

One-hundred and eight women participated in a study which screened for depressive symptoms in the antenatal period. Of these women, 92 completed at least two further screenings during the postnatal year. The screening tool was the Hamilton Depression Rating Scale, adapted for self-rating, and administered by a microcomputer. It was found that mean scores and the prevalence of depressive symptoms rose throughout pregnancy, with a sharp peak in the third trimester. Following delivery there was an abrupt fall in the prevalence of depressive symptoms, followed by another rise, with a postnatal peak at six months.There were significant associations, at all levels of severity, between raised scores antenatally, and those developing postnatally in women completing the study. These were more marked in multiparae than primiparae. There was also a significant association between a past history of treated depression and the development of raised postnatal scores for depression.The routine use of a microcomputer to administer questionnaires to patients has proved feasible within general practice.

Depression↗
PubMed1985

Effects of fluorescein on tear breakup time and on tear thinning time.

A simple, noninvasive method of in vivo precorneal tear film stability analysis is described. The method involves observing the first catoptric (first Purkinje) image. The effect of fluorescein on the results and the relation with standard tear breakup time (BUT) are presented.

Adult↗
PubMed1984

Oral beta-adrenergic blockade with metoprolol in chronic severe dilated cardiomyopathy.

A double-blind crossover trial was performed to assess the effect of metoprolol in 10 patients (mean age 55 years) with severe dilated cardiomyopathy. All patients clinically had idiopathic dilated cardiomyopathy; however, at coronary angiography, four had occult coronary disease. All were in New York Heart Association functional class III with a left ventricular ejection fraction less than 35% as assessed by rest radionuclide ventriculography. Studies were performed before treatment, after 4 weeks of metoprolol therapy and after 4 weeks of placebo administration. Erect bicycle sprint exercise was used to determine maximal work load. Hemodynamic variables and radionuclide left ventricular ejection fraction were recorded at rest and during graded supine bicycle exercise. Cardiac medications were unchanged throughout the trial. The mean (+/- standard error of the mean) dose of metoprolol was 130 +/- 13 mg/day. Metoprolol did not change symptoms, chest X-ray findings or exercise tolerance (baseline 700 +/- 73, placebo 690 +/- 85, metoprolol 710 +/- 81 kilopond-meters [kpm]/min). Metoprolol produced a significant decrease in heart rate at rest and during exercise (p less than 0.001). Mean blood pressure and left ventricular filling pressure did not differ significantly in the baseline, placebo and metoprolol studies. There was a slight, but significant (p less than 0.05) decrease in cardiac index with metoprolol compared with placebo and baseline studies. The small, but significant increase in left ventricular ejection fraction from baseline to the metoprolol and placebo studies (p less than 0.001) was considered a result of spontaneous improvement rather than of therapy. No significant differences were found between the patients with and without coronary disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1980

Sustained remission of Cushing's disease with mitotane and pituitary irradiation.

Low doses of mitotane were given orally to 36 patients with Cushing's disease, concurrently with or after pituitary cobalt irradiation. Clinical and biochemical remission occurred in 29. The response to treatment occurred early in 17 patients and late in 12. The different pattern of response to mitotane was not related to the dose given or to its serum level. Early biochemical indicators of adrenal suppression with mitotane were a sharp decrease in adrenal response to the infusion of ACTH and in plasma levels of dehydroepiandrosterone sulfate. Although mitotane was given together with pituitary irradiation, initial remission was due mainly to the adrenal effect of mitotane. Plasma ACTH levels were still elevated when cortisol had returned to normal. In seventeen of the 29 patients who responded to treatment drug therapy has been discontinued, and they remain in remission of Cushing's syndrome. Side-effects have been dose dependent, with anorexia, nausea, decreased memory, and gynecomastia in men being the commonest.

Adrenal Glands↗
PubMed1979

Temperature gradients in pigs during whole-body hyperthermia at 42 degrees C.

Temperature was simultaneously measured by thermistors in multiple deep-body and peripheral sites in adult pigs heated continuously at 42 degrees C (rectal) and above for 4-24 h. During hyperthermia, the relations between different body temperatures were maintained and up to 1.0 degrees C separated temperature measurements at sites such as liver and bone marrow. These persistent temperature gradients must be borne in mind when evaluating tumor response in patients subjected to whole-body heating for disseminated cancer. Temperatures recorded by rectal, deep esophageal, or tympanic membrane sensors provided a reliable index of core temperature (including brain temperature) under equilibrium conditions at 42 degrees C, but only esophageal and tympanic sensors could safely be used to monitor the induction phase of hyperthermia and the adjustive changes in body-heat content required to stabilize core temperature during sustained hyperthermia. Pigs withstood repeated heating at 42 degrees C for 6 h, and recovered rapidly, but died after 24 h of hyperthermia. Pigs subjected to unrestrained heating died at 45 degrees C (esophagus).

Animals↗
PubMed1978

Potential antitumor agents. Synthesis, reactivity, and cytoxicity of alpha-methylene carbonyl compounds.

The alpha-methylene lactones 9, 12, 21, and 24 were prepared by a mild, convenient alpha-methylenation process using the alpha-ethyloxalyl derivatives in nonoptimized yields ranging from 23 to 90%. The rates of reaction of these and several other lactones with cysteine at pH 7.4 and their KB toxicities were measured. These studies showed that neither the strained trans-fused alpha-methylene lactone 12 nor the hydroxy-alpha-methylene lactones 5 and 6 reacted with cysteine with rates comparable to elephantopin. Based on these limited studies, the rate of cysteine addition appears to be relatively insensitive to changes in strain energy and neighboring groups. In addition, the rate constant for reaction with cysteine did not correlate with cytotoxicity.

Antineoplastic Agents↗