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Biomedical subjects

D McBride

Publications and source records attributed to D McBride.

At least 19 recordsLinked to original sources
PubMed1996

In vivo 1H MRS choline: correlation with in vitro chemistry/histology.

We correlated the in vivo 1H Magnetic Resonance Spectroscopy (MRS) concentration of the choline peak (CHO) with in vitro chemical measures of choline-containing compounds and a histological grade of cellularity in 18 patients with neoplastic and infectious brain lesions. Gas-chromatography-mass-spectrometry (GCMS) was used to measure the concentrations of free choline (Cho), glycerophosphocholine (GPCho), phosphocholine (PCho) and phosphatidylcholine (PtdCho) from biopsies in the same area where MRS was performed. Cellular density, free Cho, PCho and GPCho were the strongest determinants of 1H MRS CHO while PtdCho was not. Just as the 1H MRS 2.0 peak reflects both the concentration of n-acetyl-l-aspartate and neuronal density, the 1H MRS 3.2 peak reflects the concentration of water-soluble choline-containing compounds and cellular density.

Brain↗
PubMed1996

Fulminant cerebral lymphoma in AIDS.

Three cases of cerebral lymphoma in patients with acquired immunodeficiency syndrome is presented. They are remarkable for their extremely rapid progression, which simulated an infectious processes during trials of antitoxoplasma therapy. Fourteen days of therapy are generally required to assess a negative response. However, earlier biopsies and shorter therapeutic trials may be indicated in these patients.

AIDS-Related Opportunistic Infections↗
PubMed1995

Posttraumatic cerebral arterial spasm.

Posttraumatic cerebral arterial spasm (vasospasm) has been demonstrated in the past by angiography, and recently by transcranial Doppler ultrasonography. Posttraumatic vasospasm is a delayed complication that involves the large basal intracranial arteries (e.g., internal carotid, middle cerebral, basilar) and occurs in 25-40% of head trauma patient. The time course of posttraumatic vasospasm resembles that of vasospasm associated with aneurysmal subarachnoid hemorrhage with onset occurring 2 or more days after injury. A study of the relationship of admission CT scan findings to the incidence of vasospasm suggests that intradural bleeding, which extends into the CSF (subarachnoid, intraventricular, and subdural hemorrhage), plays a role in the pathogenesis of posttraumatic arterial spasm. The preliminary results of a large prospective study of head trauma patients suggest that vasospasm may be an important determinant of outcome from severe head injury.

Brain Injuries↗
PubMed1995

Localized in vivo 1H magnetic resonance spectroscopy and in vitro analyses of heterogeneous brain tumors.

Results of magnetic resonance spectroscopic (MRS) studies of the chemical patterns in brain tumors have been inconsistent. Actual biochemical correlations are needed. In 2 patients with heterogeneous intracranial tumors, in vivo 1H MRS and in vitro biochemical analyses were correlated. Histology confirmed the tumor heterogeneity. Choline was elevated in the cellular portion of both tumors but decreased in the necrotic or cystic portions. Creatine was diffusely decreased while lactate was elevated in all regions of both tumors. Furthermore, the increase in the choline peak on 1H MRS appeared to be due to increases in water-soluble choline compounds. This study illustrates the value of small localized voxels for differentiating regional chemical differences in tumors.

Adult↗
PubMed1995

Brain lesions in patients with AIDS: H-1 MR spectroscopy.

PURPOSE: To evaluate the role of proton (hydrogen-1) magnetic resonance (MR) spectroscopy in the differential diagnosis of focal brain lesions in patients with acquired immunodeficiency syndrome (AIDS). MATERIALS AND METHODS: Twenty-six men with 35 AIDS-related brain lesions underwent MR imaging and localized H-1 MR spectroscopy. Lesions consisted of 11 toxoplasmic abscesses, 12 progressive multifocal leukoencephalopathic lesions, eight lymphomas, and four cryptococcomas. Metabolite peak areas in the lesions were compared with those in the contralateral hemisphere in each patient. RESULTS: H-1 MR spectroscopic findings showed significantly different biochemical profiles for each diagnostic group (P = .0001) with regard to N-acetyl compounds, total creatine pool, choline-containing compounds, myoinositol, and lactate. H-1 MR spectroscopy alone helped correctly diagnose 94% (84% with jackknifed classification) of the brain lesions, without overlap between toxoplasmosis and lymphoma. CONCLUSION: H-1 MR spectroscopy is a sensitive and potentially specific noninvasive adjunctive method for differential diagnosis of focal brain lesions in AIDS.

AIDS Dementia Complex↗
PubMed1994

Audiometry in industry.

Pure tone audiometry is the most common method of screening for hearing loss. The test itself is straightforward and the equipment readily available, so it forms part of the hearing conservation programmes of many industries. Whilst the test itself is straightforward, because of individual variability in response, interpretation of the results may be difficult. There has therefore been considerable debate on the role of audiometry in hearing conservation. The last official publication dealing with audiometry was a Health and Safety Executive discussion document 'Audiometry in Industry' published in 1978: no current recommendations are available. This article is a critical review of the advice given in that document, which aims to clarify the role that audiometry may play in the conservation of hearing. It was concluded that audiometry in the individual may perform poorly in strict cost benefit terms when used serially to detect a deterioration in hearing of an individual, but as the only form of biological monitoring it should be available to all employees who are advised to wear hearing protection at work. A distinction between audiometry in the individual and group audiometry is then made: the analysis of the hearing of a group may be useful in assessing risk to hearing. Graphical methods of analysis are shown, and more formal methods of statistical analysis discussed.

Audiometry, Pure-Tone↗
PubMed1994

In vivo proton spectroscopy of intracranial infections and neoplasms.

The chemical characteristics of 10 neoplastic and 11 infectious brain masses were studied by in vivo 1H magnetic resonance spectroscopy. In tumors, peak height ratios of n-acetyl-L-aspartate to choline were decreased compared to those in normal brain tissue and infectious masses (p < 0.02), but the ratios in normal brains and those with infections did not differ. N-acetyl-L-aspartate-to-creatine/phosphocreatine ratios were significantly lower in infectious masses and tumors compared to normal brain tissue (p = 0.003). However, in progressive multifocal leukoencephalopathy, N-acetyl-L-aspartate appeared relatively unchanged. Lactate was greater than choline in 9 of 11 brains with infection, 0 of 14 control brains, and 1 of 10 tumors. Lactate-to-choline ratios were significantly elevated in infectious masses compared with tumors (p < 0.01). 1H magnetic resonance spectroscopy is promising for the noninvasive diagnosis of focal brain masses.

Analysis of Variance↗
PubMed1994

Effects of recombinant bovine somatotrophin, insulin-like growth factor-I and insulin on bovine granulosa cell steroidogenesis in vitro.

Our previous studies have demonstrated that physiological concentrations of metabolic hormones, including recombinant bovine somatotrophin (BST), insulin-like growth factor-I (IGF-I) and insulin, can significantly stimulate the proliferation of bovine granulosa cells cultured under serum-free conditions. In this study we investigated the effects of these factors on bovine granulosa cell steroidogenesis using the same culture system. Bovine granulosa cells were obtained from antral follicles classified into three size classes: small, < 5 mm; medium-sized, 5-10 mm and large, > 10 mm in diameter. Whilst not affecting steroidogenesis by granulosa cells from small and medium-sized follicles, BST (10-1000 ng/ml) stimulated the secretion of both oestradiol and progesterone by granulosa cells from large follicles in a dose-dependent manner. Insulin (1-1000 ng/ml) and IGF-I (10-1000 ng/ml) stimulated the secretion of oestradiol and progesterone by granulosa cells from all three size categories of follicles in a dose-dependent manner. FSH (200 ng/ml) alone increased progesterone secretion by granulosa cells from all three size classes of follicles, but had no effect on oestradiol secretion by granulosa cells. Both IGF-I (200 ng/ml) and insulin (30 ng/ml) acted in synergy with FSH (200 ng/ml) to stimulate steroidogenesis by granulosa cells from all three size categories of follicles, but no such interaction was observed between BST (50 ng/ml) and FSH (200 ng/ml). In conclusion, BST, IGF-I and insulin significantly influence the steroidogenic activity of bovine granulosa cells cultured under serum-free conditions.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Tuberculosis in African-American and minority populations: historic epidemiology of a nonclassic contagious process.

This article analyzes recent medical research and health data on persistent and resurgent tuberculosis within America's African-American population and other racial minorities. Case studies and epidemiologic data suggest that the African-American and minority-American community's experience with tuberculosis control problems has diverged markedly from the nation's as a whole. The key variations include: (1) the historically higher tuberculosis incidence and mortality in African-American and other minority populations compared with whites, and (2) an emerging epidemiologic pattern of interaction between human immunodeficiency virus (HIV) and tuberculosis generally limited to African-American and minority populations. This trend results from the disproportionate spread of HIV disease in minority communities. There are new research needs in the fields of health policy theory, microbiology, molecular genetics, and behavioral sciences.

AIDS-Related Opportunistic Infections↗
PubMed1993

Acute mountain sickness in children at 2835 meters.

OBJECTIVE: Acute mountain sickness has been described in adults but little is known concerning its occurrence in children. Our objective was to determine the incidence of acute mountain sickness in children. METHODS: A survey questionnaire was completed by 558 children (aged 9 to 14 years) after they ascended from 1600 to 2835 m and from 405 similarly aged children after travel at sea level. RESULTS: Three or more of the following symptoms in the high-altitude setting were considered as the case definition of acute mountain sickness: headache, loss of appetite, vomiting, fatigue, insomnia, shortness of breath, and dizziness. One hundred fifty-six (28%) of the children at 2835 m developed acute mountain sickness. Three or more symptoms developed in a smaller, but nonetheless considerable, number (86 [21%]) of children at sea level. Headache, shortness of breath, and dizziness were reported more frequently at high altitude than at low altitude, whereas the other symptoms occurred with equal frequency at the two locations. CONCLUSIONS: More than one fourth of the children visiting high altitude developed acute mountain sickness. A high proportion (21%) of children at sea level developed similar symptoms, suggesting that an appreciable portion of the symptoms present were due to factors other than altitude, such as travel, anxiety, or disruption of daily routine.

Adolescent↗
PubMed1993

Clinical experience with multiagent intravesical therapy in interstitial cystitis patients unresponsive to single-agent therapy.

A total of 25 patients with the diagnosis of interstitial cystitis (IC) were involved in this study. All patients had been previously diagnosed with interstitial cystitis and had received treatment with single intravesical agents. Patients were divided into two groups according to their bladder capacity. The bladder capacity was > 350 ml in group I patients and < 350 ml in group II patients. For our study, dimethylsulfoxide (DMSO), methylprednisolone, and heparin sulfate were given every week for a total of 6 weeks. When symptoms recurred, supportive oral pharmacotherapy consisting of anticholinergics and/or tricyclic antidepressants was given. Under anesthesia, patients in group I showed a 99% increase in their bladder capacity; whereas those in group II showed an increase of only 19%. Cystoscopically, Hunner's ulcers were present in 60% of the group II patients but were seen in only 5% of the group I patients. Histopathological examination showed that the inflammatory changes were more frequent and severe in group II than in group I. Mast-cell hyperplasia was present in 100% of the patients in group II, versus only 61% of those in group I. A total of 23 patients (92%) achieved an initial remission averaging 8.1 months. In all, 9 patients (35%) had 1 or more relapses, and all achieved a subsequent remission averaging 8 months. By this combined multiagent approach, the majority of patients with IC obtained relief from their incapacitating symptoms and were socially rehabilitated.

Administration, Intravesical↗
PubMed1993

Hearing conservation in the mining industry. Evaluation of a risk factor questionnaire.

The objectives of this study were to assess the validity of a self-administered hearing questionnaire in the assessment of risk to hearing, to amend the questionnaire design as necessary, and to give general guidance on the use of audiometric questionnaires in hearing conservation programmes. The study was carried out at a colliery in Staffordshire. The odds of deafness, according to the Health and Safety Executive definition, were analysed by exposure to the hearing risk variables in the questionnaire. The results of the hearing questionnaire were linked to a cross-sectional audiometric survey. There were 189 questionnaires eligible for inclusion. Noise exposure at work was reasonably well predicted by having to shout at work (OR 1.42, 95 per cent CI 0.58-3.54) and being exposed to noisy tools and machinery (OR 2.12, 95 percent CI 0.72-6.72). Risk to hearing from disease was predicted by having 'abnormal' hearing or discharging ears, but not by any of the other exposure variables. Risk to hearing from acoustic trauma was demonstrated for fire-arms (OR 1.23, 95 per cent CI 0.5-2.98). None of the hobbies included in the questionnaire usefully predicted hearing loss. The conclusions are that, contrary to Health and Safety Executive advice, audiometric questionnaires may reasonably be administered to all employees, as they are useful in the documentation of hearing loss risk factors. They should not, however, be used to detect ear disease. A revised questionnaire was drafted as the result of these findings, and will be piloted in a larger population.

Evaluation Studies as Topic↗
PubMed1993

Black America: from community health care to crisis medicine.

This study traces the major policy shifts in medical care that have affected disadvantaged African-Americans and the response of this community's medical leadership to these changes. Since World War II policy has passed through three major phases. The first--engagement--ran from the mid-1960s through the mid-1970s. During this phase a community health policy orientation prevailed as national government targeted resources to health care programs for needy blacks and other poor Americans. From the late 1970s to the mid-1980s the period of submersion occurred: black community health professionals and political leaders experienced a new-found inclusion in health policy debate, but, at the same time, broader policy-making circles in government and health care reduced medical resources for the inner-city poor. Finally, in the third phase--crisis recognition--a network developed of community health advocates who seek to reorient the health system so that it addresses needs within urban American's "New Ghettos."

Black or African American↗
PubMed1993

Effects of recombinant bovine somatotrophin, insulin-like growth factor-I and insulin on the proliferation of bovine granulosa cells in vitro.

Treatment of heifers with recombinant bovine somatotrophin (BST) significantly increases the population of small ovarian follicles and peripheral concentrations of somatotrophin, insulin-like growth factor-I (IGF-I) and insulin. To investigate the possible mechanism(s) involved in the action of BST on ovarian follicles, the effects of BST, IGF-I and insulin, given alone or in combination with either FSH or LH, on the proliferation of bovine granulosa cells in vitro were examined using a serum-free culture system. Bovine granulosa cells were obtained from antral follicles classified into three size categories according to diameter: small < 5 mm; medium-sized 5-10 mm and large > 10 mm. The proliferation of granulosa cells was assessed by the incorporation of [3H]thymidine into the cultured cells. Both FSH and LH (1-1000 ng/ml) inhibited the proliferation of bovine granulosa cells obtained from all three size classes of follicles in a dose-dependent manner. BST, at doses ranging from 1 to 1000 ng/ml, had no effect on the proliferation of granulosa cells from small and medium-sized follicles, but inhibited the division of granulosa cells from large follicles in a dose-dependent manner. Treatment with either IGF-I (10-3000 ng/ml) or insulin (0.5-1000 ng/ml) stimulated, in a dose-dependent manner, the proliferation of granulosa cells obtained from all three size categories of follicles. No synergistic interaction between BST (30 ng/ml) and either FSH (50 ng/ml) or LH (5 ng/ml) was observed in granulosa cells from all three size classes of follicles.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗