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Biomedical subjects

M Barker

Publications and source records attributed to M Barker.

At least 73 records · Page 4Linked to original sources
PubMed1996

Persisting unilateral lung hypoperfusion after resection of a subcarinal bronchogenic cyst.

As a rare malformation with a wide variety of clinical modes of presentation, the bronchogenic cyst remains a diagnostic challenge. We report a case with a subcarinal bronchogenic cyst and stenosis of the left main bronchus presenting as "unilateral hyperlucent lung". Hypoplasia of the ipsilateral pulmonary vascular system persisted after surgical restitution of ventilation and is most likely due to an associated vascular malformation. Alternatively, anatomical fixation of pulmonary reflex vasoconstriction can be discussed.

Adolescent↗
PubMed1995

The effects of fumonisin B1 on several markers of nephrotoxicity in rats.

Rats were injected intraperitoneally with saline or fumonisin B1 (FB1) at doses of 7.5 and 10.0 mg FB1/kg for 4 days. For each day of dosing, 24-hr urine samples were collected and analyzed for creatinine and protein content and the enzymes gamma-glutamyl-transpeptidase, lactate dehydrogenase, and N-acetyl-beta-D-glucosaminidase. Twenty-four hours after the last dose, animals were killed and kidneys removed for ion transport measurement and histopathology. Significant increases in urine volume and decreases in urine osmolality were observed in both FB1 dose groups. Creatinine excretion was decreased only in the 10 mg FB1/kg group on the final day of the study. Urine protein excretion was elevated in both treated groups and found to be due primarily to high-molecular-weight proteins indicative of increased glomerular permeability. Enzymuria, a marker of tubular cell damage, was also observed with increases in the urinary excretion of all three enzymes measured. In renal cortical slices tubular transport of the anion p-aminohippuric acid was reduced by 75-80% and cationic transport of tetraethylammonium was reduced by 40% in the FB1-treated animals. While these results suggest significant alterations in renal function, only minor histopathologic changes were observed in the kidneys of both dose groups. Results of the present study indicate that urine volume, proteinuria, enzymuria, and ion transport are sensitive indicators of early FB1-induced nephrotoxicity.

Animals↗
PubMed1995

Diastolic dysfunction is not related to changes in glycaemic control over 6 months in type 2 (non-insulin-dependent) diabetes mellitus. A cross-sectional study.

Diastolic dysfunction may be the earliest marker of a diabetes-induced heart muscle disease which leads to the progressive development of cardiac failure. Left ventricular diastolic function was indirectly assessed using pulsed wave Doppler ultrasound mitral-flow velocities in 20 normotensive patients with a new diagnosis of type 2 diabetes mellitus, normal cardiac function and no evidence of coronary artery disease and in 16 age-matched normal subjects. Peak velocities of early (E) and late (A) left ventricular filling were measured. The median (interquartile ranges) peak E/A ratio was significantly reduced in the diabetic group 0.96 (0.8-1.2) vs 1.2 (1.1-1.3), P < 0.01. Despite improvements in glycaemic control over 3 months, HbA1c 9.9% (7.6%-10.5%) to 7.4% (6.5%-7.9%), P < 0.001, maintained at 6 months, HbA1c 7.0% (6.4%-7.3%), there were no changes in the E/A ratio, 0.96 (0.83-1.15) and 0.95 (0.83-1.17), respectively. Furthermore, there was no correlation between percentage change in HbA1c and E/A ratio over 6 months. The results of this study suggest that in patients with type 2 diabetes mellitus and normal systolic function, diastolic function was impaired at diagnosis and was not affected by an improvement in the glycaemic control.

Blood Glucose↗
PubMed1995

Toxicity of fumonisin B1 administered intraperitoneally to male Sprague-Dawley rats.

The toxicity of purified fumonisin B1 (FB1) administered ip was examined in male Sprague-Dawley rats. FB1 was injected at 7.5 or 10 mg/kg body weight/day for 4 consecutive days. This resulted in significant reductions in body weight, food consumption and faeces production. Polyuria without a compensatory increase in water consumption was observed in treated rats. Erythrocytosis, elevated haematocrits and haemoglobin levels were attributed to dehydration. Nephrotoxicity in treated rats was evident by clinical changes including elevated blood urea nitrogen and by subtle changes in kidney morphology. Histopathology and serum biochemistry also indicated that the liver was an important target organ in FB1-treated rats. A small increase in liver glutathione concentration was also evident in rats receiving 10 mg FB1/kg body weight. Effects on the immune system included reduced thymus weight, disseminated thymic necrosis and consistently elevated serum immunoglobulin M levels. Circulating phagocytic cell numbers were elevated in treated rats, probably owning to tissue damage associated with ip dosing. The liver and kidneys appear to be target organs of FB1 in Sprague-Dawley rats.

Animals↗
PubMed1995

Evidence of HLA class II association with antibody response against the malaria vaccine SPF66 in a naturally exposed population.

The antibody response against the malaria vaccine SPf66 and against circumsporozoite (CS) protein has been tested in immune adults from a malaria endemic area in Papua New Guinea. All individuals were genotyped for the HLA class II DQB1 and DRB1 loci, and the humoral response was analyzed with respect to the identified class II alleles. At each locus, only three alleles were frequent, namely DRB1*11, *15, and *16, and DQB1*0301, *0502, and *0601. Antibodies against SPf66 and CS protein were found in 84% and 79% of the individuals, respectively. A strong negative association was detected between the humoral response against SPf66 and DRB1*15 and DQB1*0601. A positive association of the response was observed with DRB1*11 and DQB1*0301. After analysis with a multiple regression model in which all alleles were included simultaneously, only DRB1*15 remained significantly associated with low antibody responses. This suggests that nonresponders may be expected after immunization with SPf66 in certain populations.

Adolescent↗
PubMed1994

Small terminal deletions of the long arm of chromosome 2: two new cases.

We report on 2 girls with small de novo terminal deletions of the long arm of chromosome 2 and breakpoints within q37. Four cases with similar or more extensive deletions have been previously reported in full. Hypotonia and psychomotor retardation were the only manifestations common to all 6 cases. The phenotype associated with small terminal 2q deletions is variable and clearly not always as mild as indicated in previous reports. The abnormality may also be more common than has been assumed.

Child↗
PubMed1993

Disability in young adults: the role of injuries.

STUDY OBJECTIVES: To describe the prevalence of disability in young adults and estimate the contribution that injuries make to disability. DESIGN: The study uses data from a British longitudinal survey, the National Child Development Study (1958 cohort). Disability at age 23 was ascertained from three questions asked in an interview with cohort members in 1981: these related to longstanding illness that limits activity, permanent disability following an accident after age 16, and registered disability. Lower and upper estimates of the contribution of injuries to disability were derived from ICD-9 codes allocated to the disabilities. SUBJECTS: These comprised 12,537 subjects, representing 76% of the target population, cohort members still alive and resident in Britain in 1981. MAIN RESULTS: Prevalence of disability according to the three definitions was: 46 per 1000 with limiting longstanding illness; 28 per 1000 with a permanent accident related disability of onset after age 16; and 10 per 1000 registered disabled. Combining all three definitions, the overall prevalence of disability was 68 per 1000, with men reporting more disability than women. It was estimated that an injury caused the disability for 16.7% of subjects, at the lower estimate, and 26.0% at the upper estimate (23.1% to 32.1% for men and 8.6% to 18.4% for women). For limiting longstanding illness of onset after 16, between 33.5% and 47.8% was due to an injury. Road accidents caused 31% of permanent accident related disability. Over one half of men and nearly three quarters of women reporting permanent accident related disability had not been admitted to hospital for their injury. CONCLUSIONS: Injuries are an important cause of disability in young adults, particularly injuries resulting from accidents after age 16. Accident prevention in the 16-24 group has the potential to reduce the prevalence of disability substantially.

Accidents↗
PubMed1992

Experimental basis for increasing the therapeutic index of cis-diamminedicarboxylatocyclobutaneplatinum(II) in brain tumor therapy by a high-zinc diet.

Metallothionein (MT), a ubiquitous intracellular protein, confers resistance to the toxic effects of platinum compounds. Since a high-zinc diet has been shown to induce MT synthesis in extracerebral tissues but not in brain, we investigated whether it could provide an experimental basis for decreasing the hematotoxicity of carboplatin without impairing its activity against brain tumors. After 2 weeks on either a high-zinc diet or a control diet (zinc content, 180 vs 10 ppm), mice and rats received various doses of carboplatin or Hanks' balanced salt solution by i.p. injection. The hematotoxicity of carboplatin was evaluated with an assay of colony-forming units of granulocytes and mononuclear cells in mice. The high-zinc diet enabled a 50% increase in the carboplatin dose without increasing hematotoxicity. The antitumor activity was evaluated with an assay of the colony-forming efficiency of gliosarcoma cells from 9L brain tumors in rats. The high-zinc diet did not alter the efficacy of carboplatin against this brain tumor. Northern blot analysis confirmed that the high-zinc diet induced MT mRNA in the kidney but not in the brain of mice and rats; it also showed MT mRNA induction in bone marrow cells of mice but not in rat 9L brain tumors. These results suggest that increasing the dietary intake of zinc might increase the therapeutic index of carboplatin in the treatment of brain tumors.

Animals↗
PubMed1991

A re-evaluation of the osteoarticular manifestations of psoriasis.

A distinctive peripheral arthropathy associated with psoriasis is well recognized, the classical pattern describing an asymmetrical oligoarthritis with predominant distal interphalangeal joint (DIP) involvement. There is some dispute about the frequency of this classical pattern and of the pattern of symmetrical polyarthritis resembling rheumatoid arthritis. Some of the dispute may be a result of loose definitions. In this clinical and scintigraphic study of 50 patients with psoriatic arthritis we have used tighter definitions of disease pattern and have found that 68% of this group had a symmetrical polyarthritis similar to that found in rheumatoid arthritis. Yet, arthritis associated with psoriasis differs from rheumatoid arthritis in a number of ways including the pattern of joint involvement, extra-articular osseous features, and radiological changes. Scintigraphic changes in psoriatic arthritis suggest that subclinical involvement of the manubriosternal and sternoclavicular joints is common, suggesting an association between psoriasis vulgaris and arthro-osteitis. A modified classification of the osteoarticular manifestations of psoriasis is proposed.

Adult↗
PubMed1991

Functional use of the Nucleus 22-channel cochlear implant in the elderly.

A questionnaire was sent to 101 Nucleus 22-channel cochlear implant recipients aged 65 years and older to investigate the perceived impact of cochlear implantation on their quality of life. The questionnaire was designed to gain insight into the patient's daily use of the Nucleus implant. Sixty-seven questionnaires were returned over a 3-month period. The results of the survey showed that elderly cochlear implant patients obtained similar benefits to younger adult patients who were implanted with the same device. We believe that the results of this study will aid other centers when counseling elderly patients on the expected daily functional benefits of this device.

Aged↗
PubMed1991

Laryngeal examination: a comparison of mirror examination with a rigid lens system.

Indirect mirror laryngoscopy is the standard screening examination used in patients with complaints referable to the larynx and upper aerodigestive tract. The purpose of this study was to prospectively evaluate, in 100 patients, the diagnostic accuracy and examination success rate of indirect laryngoscopy versus a rigid rod examination. Fifty-two percent of mirror examinations were successful as were 83% of rod exams. This was a significant difference in success rate. From the 29 patients who underwent direct laryngoscopy, one false negative and one false positive mirror examination and one false positive rod examination were found. We conclude that the mirror is a useful screening tool so long as strict examination criteria are used. The rigid rod adds further diagnostic information in those patients who cannot be evaluated with a mirror.

Equipment Design↗
PubMed1990

Cell kinetics of rat 9L brain tumors determined by double labeling with iodo- and bromodeoxyuridine.

Rats with 9L brain tumors received intraperitoneal injections of iododeoxyuridine (IUdR) and bromodeoxyuridine (BUdR) to estimate the duration of the deoxyribonucleic acid (DNA) synthesis phase (Ts) and the potential doubling time (Tp) of individual tumors. Different sequences and intervals (2 or 3 hours) of IUdR and BUdR administration were evaluated. After denaturation, tumor sections were reacted with Br-3, a monoclonal antibody that identifies only BUdR, and then were stained immunohistochemically by the avidinbiotin complex method. An antibody that recognizes both IUdR and BUdR, IU-4, was applied to the sections and identified by the alkaline phosphatase-antialkaline phosphatase method. Nuclei labeled only with IUdR stained blue, while those labeled with BUdR or with BUdR and IUdR stained brown. The fraction of cells that either left or entered the S-phase during the time between administration of IUdR and BUdR was measured to calculate Ts and Tp, assuming that the labeled cohort completed the DNA synthesis at a constant rate. The Ts was 8.8 hours (coefficient of variation (cv) = 0.05) and the Tp was 64.2 hours (cv = 0.08). The sequence and interval of administration of IUdR and BUdR had a minimal effect on Ts and Tp. In studies of 9L cells in monolayer culture, the Ts was 9.6 hours (cv = 0.08) and the TP was 30.6 hours (cv = 0.06). Double labeling with BUdR and IUdR allows the duration of the S-phase and potential doubling time of individual brain tumors to be estimated in situ from a single biopsy specimen.

Animals↗
PubMed1989

Blood-brain barrier to pertechnetate following drug-induced hypotension.

The integrity of the blood-brain barrier (BBB) was examined in rabbits, in terms of the partition of 99mTc-pertechnetate (99mTcO4-) between brain and blood, following intracarotid injection of hypertonic arabinose, hypertension (168 mm Hg and 10% inspired carbon dioxide), or hypotension (less than 20 mm Hg for 15 min). Corrections were made for changes in tissue blood contents, using chromium-51 as a red cell marker. In control animals the mean brain:blood ratio was 0.038 (range 0.027-0.052). Following arabinose there was a five-fold increase in mean BBB permeability (mean brain:blood ratio 0.192 (0.070-0.378)). There was no change after hypertension and carbon dioxide (mean ratio 0.034) or after hypotension (mean ratio 0.032), despite an increase in cerebral extracellular potassium. Examination of other tissues showed no change in the 99mTcO4- tissue/blood partition in heart muscle in any study but, following hypotension, ratios in the kidney (mean ratio 1.63) and, to a lesser extent, the liver (mean ratio 1.37) had increased, suggesting an abnormality of active transport under these conditions. We conclude that, while 99mTcO4- tissue/blood partitioning revealed osmotic disruption of the BBB, profound hypotension with evidence of brain cell damage did not change BBB permeability to the same marker. Hypotension may influence active transport of this ion in liver and kidney.

Animals↗