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Biomedical subjects

A McLean

Publications and source records attributed to A McLean.

At least 19 recordsLinked to original sources
PubMed1992

Lifespan of human lymphocyte subsets defined by CD45 isoforms.

The lifespan of thymic-derived or T lymphocytes is of particular interest because of their central role in immunological memory. Is the recall of a vaccination or early infection, which may be demonstrated clinically up to 50 years after antigen exposure, retained by a long-lived cell, or by its progeny? Using the observation that T lymphocyte expression of isoforms of CD45 corresponds with their ability to respond to recall antigens, we have investigated the lifespan of both CD45R0 (the subset containing responders, or 'memory' cells) and CD45RA (the unresponsive, or 'naive' subset) lymphocytes in a group of patients after radiotherapy. Here we report rapid loss of unstable chromosomes from the CD45R0 but not the CD45RA pool. Immunological memory therefore apparently resides in a population with a more rapid rate of division. Differing survival curves for the two subsets are best described by a model in which there is also reversion in vivo from the CD45R0 to the CD45RA phenotype. Expression of CD45R0 in T cells may therefore be reversible.

Chromosome Aberrations↗
PubMed1992

Indomethacin and postprandial gallbladder emptying.

Patients with gallstone disease commonly have impaired gallbladder emptying. To see whether non-steroidal anti-inflammatory drugs (NSAIDs) prevent gallstone formation by improving gallbladder emptying, we assessed the effect of indomethacin on postprandial emptying in healthy subjects and in patients with gallstone disease. Subjects received indomethacin 25 mg three times a day for a week and matching placebo for another week. Compared with placebo, indomethacin improved postprandial gallbladder emptying in all 7 patients with gallstone disease. This finding was not recorded in healthy subjects with normal gallbladders. The prevention of gallstone formation associated with ingestion of NSAIDs may be due mainly to a prokinetic effect on the gallbladder since there is no evidence to suggest that these drugs affect cholesterol crystal nucleation at ordinary therapeutic doses in man or animals.

Adult↗
PubMed1992

Elderly patients and their medication: a post-discharge follow-up study.

Fifty-six elderly patients (age range 65-98 years) discharged from a geriatric unit were visited at home on or after the 5th post-discharge day (median day 8) and their medication assessed. By the day of the visit, 15 of the 56 had not had a new prescription issued (27%) and 27 patients (48%) had old prescribed medication at home. Forty-one new scripts, issued by general practitioners, should have contained 128 medications if the general practitioners wished to continue unchanged the medication given on hospital discharge. Fourteen drugs (11%) had been added and 17 drugs (13%) omitted. The number of prescriptions issued unchanged was 26/41 (63%). Inaccurately labelled containers and/or changed drug names were found in 28%. Contrary to hospital advice, 47% of medications were issued in childproof containers. Poor communication between hospital and general practitioners is only part of the problem. Methods to expedite the delivery of new prescriptions should be developed.

Aged↗
PubMed1992

Microscopic and macroscopic measurements of emphysema: relation to carbon monoxide gas transfer.

BACKGROUND: Studies of the relation between the severity of structural change in emphysema and physiological abnormality have been based on macroscopic assessments, which have not been truly quantitative or sensitive enough to detect early changes. With a highly reproducible method for measuring emphysema using histological sections and a semiautomatic image analysis system, this quantitative assessment of emphysema was compared with a semiquantitative macroscopic assessment of emphysema and measurements of carbon monoxide gas transfer. METHODS: Microscopic and macroscopic measurements of emphysema on 44 thoracotomy specimens were compared; only two were from non-smokers. Airspace wall surface area per unit volume was measured microscopically with an automatic image analyser and expressed as both the mean airspace wall surface area per unit volume and the mean value of the five fields with the lowest values. Macroscopic emphysema was measured directly on a tracing of the midsagittal slice using a digitising tablet attached to a microcomputer and expressed as a percentage of the total area of lung. In cases with centriacinar emphysema the number of discrete lesions was counted. RESULTS: The area of macroscopic emphysema ranged from 0 to 78% of the total area of lung examined, but most patients had less than 1% involvement so that the distribution was highly skewed. Both mean airspace wall surface area per unit volume and the mean of five fields with the lowest airspace wall surface area per unit volume were normally distributed, with mean airspace areas ranging from 8.8 to 25.4 mm2/mm3 (mean 18.1 mm2/mm3). In lobes with centriacinar emphysema the number of discrete lesions correlated with airspace wall surface area per unit volume and with preoperative carbon monoxide transfer factor (TLCO) per unit lung volume. However, other measurements of macroscopic emphysema did not correlate with loss of alveolar wall surface area, and there was considerable overlap between subjects with no or minimal macroscopic emphysema and those with more severe disease. TLCO correlated with both mean airspace wall surface area per unit volume and the mean of five fields with the lowest airspace wall surface area per unit volume but not with the severity of macroscopic emphysema. CONCLUSION: If emphysema is to be quantified it must be measured microscopically; macroscopic measurements do not, in general, reflect the microscopic loss of airspace wall.

Aged↗
PubMed1992

Changes in neutrophil morphology and morphometry following exposure to cigarette smoke.

Acute cigarette smoking delays neutrophils within the pulmonary circulation in some smokers. Evidence from an in-vitro Micropore filter model of the pulmonary capillaries indicates that this may be due to a smoke induced decrease in cell deformability. In order to determine whether changes in cell shape are associated with the observed decrease in neutrophil deformability following smoke exposure, cell morphology, using scanning electron microscopy, and morphometric measurements, made using transmission electron microscopy, were performed on aliquots of neutrophils harvested from whole blood in non-smoking subjects before and after exposure in vitro to cigarette smoke. Smoke exposure increased the maximum diameter and circumference of neutrophils, without changing their area. There was also a change in the maximum to minimum cell diameter ratio, which indicated that the cells had become less spherical. Scanning electron microscopy showed that smoke exposed cells had developed blebbing of their surface membranes, suggestive of an oxidative injury to the cell membrane rather than the shape changes associated with cell activation. These changes in the morphology and morphometry of smoke exposed neutrophils may contribute to the reduction in cell deformability induced by cigarette smoke.

Anthropometry↗
PubMed1991

Thick malignant melanomas (greater than 3 mm Breslow) with good clinical outcome: a histological study and survival analysis.

Thick malignant melanomas in general tend to have a poor prognosis, but exceptions occur where there may be no further recurrence. The reasons for this difference in clinical behaviour are not fully understood. We have looked at thick malignant melanomas (greater than 3.0 mm) in the East of Scotland that have no evidence of metastasis after a minimum of 6 years follow-up and compared the clinical and histological features with a similar group, associated with histological evidence of metastasis and/or death. Both groups received similar treatment regimes. We have identified 41 patients with thick melanomas in the former group. When compared with the control group, factors found to be significantly different between the two groups were: the nature of the lower margin of the tumour; vascular invasion; and anatomical location.

Adolescent↗
PubMed1991

Use of phenytoin to treat horses with Australian stringhalt.

Five horses with Australian stringhalt were treated with 15 mg/kg phenytoin orally for 2 weeks. During the second week of the trial, 3 of the horses were given an additional dose of 10 mg/kg phenytoin. The response to treatment was clinically assessed by grading the severity of the gait abnormality at the walk, trot, turning and backing twice daily. There was a significant (P less than 0.05) improvement in the gait abnormality when pre-treatment values were compared with the mean of the last 3 assessments before treatment stopped. When reassessed 2 weeks after treatment ceased, there remained a significant (P less than 0.05) improvement compared with pre-treatment values at the trot and on backing, but not at the walk or turning. Surface electromyographic recordings were made weekly from the long digital extensor muscle, and there was a change to a near normal recording by the end of treatment. Plasma phenytoin concentrations were monitored during the trial, and the dose rates used achieved a steady state with a mean plasma level of 37 +/- 7 mumol/l. There was wide variability between plasma concentrations in different horses, although there was no difference in absorption between administration of the phenytoin as a paste, or when it was mixed in the feed. Although mild tranquilization was seen after treatment, there were no clinical, haematological or biochemical signs of toxicity from the phenytoin therapy.

Administration, Oral↗
PubMed1991

Relative effects of brain and non-brain injuries on neuropsychological and psychosocial outcome.

Based on the 242 consecutive surviving head injury cases and 132 general trauma cases, this study examined the contribution of brain and non-brain injuries to cognitive and psychosocial outcome 1 month postinjury. The study also examined the relationships among various head injury severity indices. The head injury severity indices were all correlated but patients with Glasgow Coma Scale scores in the mild range had broadly ranging scores on the other head injury severity indices (Abbreviated Injury Scale and time to follow commands). Neuropsychological outcome was related to brain injury severity, but was not independently influenced by severity of other systems injuries. Psychosocial outcome related to both brain and non-brain injuries independently. When evaluating trauma outcome, it is important to consider the contributions of both brain and other system injuries.

Abbreviated Injury Scale↗
PubMed1991

Fatigue and depression in brain-injured patients correlated with quadriceps strength and endurance.

Many brain-injured (BI) patients complain of persistent fatigue that may alter their lifestyles. In order to assess muscular strength and endurance after brain injury, 22 BI men, greater than 9 months postinjury and aged 20 to 51 years, were separated into two groups based on a complaint of fatigue (fatigue n = 13, nonfatigue n = 9); each performed one maximal isometric knee extension at 60 degrees and 20 maximal isokinetic contractions at 20 rpm using a Cybex II dynamometer. A third group of age-matched, able-bodied men (n = 10) were used as controls. A battery of tests assessing the presence of fatigue (using a symptom checklist and two rating scales), depression, anxiety, and health status were given at the time of isokinetic/isometric testing. The mean fatigue rating, a subjective score, for the fatigue group of BI subjects was significantly worse than the other groups (p less than .01). There was a positive correlation between clinically significant Zung depression scores and fatigue rating (r = .46) and between Zung anxiety scores and fatigue rating. The depression scores for those who complained of fatigue were significantly higher than the other groups (p less than .005). Maximal isometric contractions were no different among the three groups. The mean maximal isokinetic torque during the 20 repetitions was greater in controls than in the BI groups, but did not reach statistical significance (p less than .25). There were no significant declines in isokinetic torque in the 20 repetitions for any of the groups, and the fatigue index was nearly equal for all three groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Contradictions in the social production of clinical knowledge: the case of schizophrenia.

This paper is divided into two parts. In Part I, I contend that the current thrust to synthesize clinical and critical medical anthropology is misdirected and may serve to further fragment, rather than unify their concerns. I then suggest that instead of focusing on their differences, either in levels of analysis ('micro-' versus 'macro-') or in objects for analysis, we should emphasize instead the perspective that they share--one drawn from the common task their work assumes as a critical, emancipatory science of mankind. In Part II, keeping in mind this short prolegomenon, I utilize data regarding the National Alliance for the Mentally Ill (NAMI) to illustrate that medical knowledge is reducible to neither natural nor social forces; it is instead produced by living actors who are constrained by their social and historical conditions and the exigencies of the mode of production in which these actors produce. I show how NAMI members have succeeded in changing 'blame-the-family' ideologies about schizophrenia etiology and treatment, but I also explain how the medicalized alternative they produced in redefining schizophrenia as a disease of the brain is itself limited and fraught with contradictions (e.g. reinforcing a depersonalizing mind/body separation that inhibits healing). These contradictions highlight the difficulty of transcending the assumptions implicit in medical categories since they are tied to the dominant epistemology of the mode of production in which they are produced--one that binds our world views and limits the options we can generate. Anthropologists must draw attention to these constraints as an initial step to transcending them.

Anthropology↗
PubMed1990

Diaphragmatic (Bochdalek) hernias simulating pulmonary metastases on computed tomography.

Three patients with known primary malignancy and a normal chest radiograph are presented. Computed tomographic scans viewed on 'lung' settings showed a solitary mass lesion simulating a neoplastic mass in the posterior costophrenic recess in each patient. These lesions in fact were small herniations of abdominal fat into the chest through diaphragmatic defects.

Aged↗
PubMed1990

Neuropsychological recovery in patients with moderate to severe head injury: 2 year follow-up.

Neuropsychological outcome and recovery of a group of 31 consecutive adult patients with moderate to severe head injuries were prospectively investigated over a 2-year period. A friend control group was used for comparison purposes. Based on the results we conclude: (1) there is marked impairment of a broad spectrum of neuropsychological functions at 1, 12, and 24 months postinjury; (2) coma length is significantly related to neuropsychological status at all three time periods, although the relationship is weaker at 12 and 24 months; (3) marked improvement in all functions occurs in the first year, while recovery in the second year appears more specific and may depend on the severity of the injury and type of function; (4) practice effects and variability over repeated measures cause difficulties in determining recovery and need to be addressed with larger samples.

Adult↗
PubMed1990

Thin malignant melanomas (less than 1.5 mm) with metastasis: a histological study and survival analysis.

It is known that not all thin malignant melanomas have an excellent prognosis and that the specific features identifying the patients at risk of metastasis have not been fully elucidated. We have looked at thin malignant melanomas (less than 1.5 mm) in the East of Scotland that had proven metastasis and death, and compared the clinical and histological features with a similar group (less than 1.5 mm) that have had no further recurrence after a minimum of 6-year follow-up. We identified 26 patients with thin melanomas who had developed histologically proven metastasis and/or died following adequate surgical treatment of their primary lesion. When compared with the control group, factors found to be significantly different between the two groups and present in the group that did badly were (a) histological regression, (b) lesion size, (c) Clark level IV and (d) depth of the uninvolved dermis.

Adult↗
PubMed1990

Alcohol use as a situational influence on young women's pregnancy risk-taking behaviors.

Recent studies have found that many young women just beginning their sexual lives use alcohol prior to intercourse. A large number appear to drink heavily enough prior to sex to compromise their ability to use contraceptives. The question emerges whether there is a relationship between drinking before intercourse, the nonuse of birth control methods, and unplanned pregnancies. The present research describes 43 instances of intercourse which resulted in unplanned pregnancies in 14- to 21-year-olds. Variables examined included alcohol use prior to sex, amount of alcohol consumed, the use of other drugs, the planning of intercourse, respondents' stated reasons for nonuse of contraceptives, and other general demographic data.

Adolescent↗
PubMed1989

Evaluation of a serologic marker, CA19-9, in the diagnosis of pancreatic cancer.

STUDY OBJECTIVE: To determine the utility of the serologic marker CA19-9 in the diagnosis of pancreatic cancer in patients suspected of having a pancreatic disorder. DESIGN: Blinded study of frozen pedigreed serum samples collected at time of diagnostic evaluation with follow-up review at a mean of 8 years. SETTING: A general university teaching hospital serving both primary and referral patient populations. MEASUREMENTS AND MAIN RESULTS: Sera collected prospectively from 1978 to 1980 from 261 patients undergoing imaging studies of the pancreas (ultrasound, computed tomography, endoscopic retrograde cholangiopancreatography) for a variety of symptoms were assayed for CA19-9 levels, and the results were compared with earlier determinations of other potential markers for pancreatic cancer. In 54 patients ultimately shown to have pancreatic cancer, the CA19-9 assay showed a sensitivity of 70% with a median value of 349 u/mL (normal less than 70 u/mL) and range, 7.3 to 2,859,964 u/mL, whereas specificity of the marker in this population was 87%. The positive predictive value was 59%, and the negative predictive value was 92%. Results of CA19-9 testing in the small group of patients with definitive staging information showed no difference in sensitivity between patients with local/regional disease (n = 6) and those with distant metastases (n = 14), 50% compared with 71% (P = 0.613). CONCLUSION: CA19-9 was found to be a more sensitive and specific marker of pancreatic cancer than other serologic markers and should be a useful test in the patient with suspected pancreatic disease.

Adenocarcinoma↗