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Biomedical subjects

B Brown

Publications and source records attributed to B Brown.

At least 253 records · Page 14Linked to original sources
PubMed1986

Reaction time in age-related maculopathy.

As part of our study of visual functions in age-related maculopathy (ARM) we tested reaction times to red lights of the same size and chromaticity as traffic signals. We tested under photopic and mesopic conditions with both central fixation and fixation at 5 degrees eccentricity. We examined four groups of subjects--two with normal vision, one young and the other elderly, one group of subjects with definite ARM, and another group of subjects with ophthalmoscopically visible macular changes but clinically normal visual functions, denoted preARM (PARM). There were significant differences between each of the groups tested. The ARM group showed greatly prolonged reaction time compared to the elderly normal subjects, whereas the preARM group had results between these two groups. The results indicate that functional changes are present before ARM can be diagnosed by conventional means; the consequences of these changes for the elderly motorist are discussed.

Adult↗
PubMed1986

Cone adaptation in age-related maculopathy.

Cone adaptation was measured in patients with age-related maculopathy (ARM) and age-matched controls. A red stimulus was used to selectively bias responses toward cone function and adaptation was measured 5, 10, 20, and 40 degrees eccentric to fixation. The ARM patients' thresholds were elevated by 1 log unit at 5 and 10 degrees, with the threshold difference reducing to 0.5 log units at 40 degrees. Curves of the form log (threshold luminance) = ae-bt + c (where t is time and a, b, and c are constants) were fitted to each adaptation curve; a procedure involving differentiation of the above equation was used to estimate the constant parameters. Time constants of cone recovery (1/b) were derived for each fitted curve. No significant difference was found between the time constants of the two test groups. Our data suggest that cone adaptation is significantly affected in patients with ARM, with raised cone thresholds occurring for areas well into the peripheral retina. We suggest that the effect is mediated by a reduction in the number of functional cones, which elevates the final cone thresholds without altering the adaptation time constant. Our findings imply that age-related "maculopathy" may not be confined to the macular area, and that early signs of the degeneration may be present in the peripheral retina even when central acuity is normal.

Adaptation, Physiological↗
PubMed1986

Contribution of vision variables to mobility in age-related maculopathy patients.

Can mobility performance be predicted from measures of vision function? This study addressed this question by measuring a series of vision variables including visual acuity, visual fields, and differential motion sensitivity in a group of patients with age-related maculopathy (ARM) and a group of age-matched normals. Mobility performance at three adaptation levels was determined objectively on an indoor course. The results indicate that for the patients with ARM, mobility variables can be predicted from measures of vision function, including differential velocity sensitivity, and that simple variables such as time taken to complete the course and average speed are those which relate best to vision.

Aging↗
PubMed1986

The development of longitudinal patterns in the rabbit cerebellum.

Reconstruction of several AChE series (from day E 18 after conception till after birth and in maturity) demonstrate that reaction products are localized in alternating positive and negative longitudinal strips. Till day E 26 the AChE activity is topographically related to certain Purkinje cell (P-cell) clusters and located around P-cells. At day E 24 till day E 26 AChE activity shirts into the marginal layer. At day E 28 AChE activity is present at the P-cell layer, around P-Cell somata and their dendrites. The longitudinal band pattern is still present at this age. Around birth AChE activity shifts into the granular layer, constituting a longitudinal AChE pattern. The changes in the localization of AChE are first observed in the anterior lobe and occur later in the posterior lobe vermis and hemispheres. At maturity the longitudinal AChE activity has disappeared from the P-cell layer, but a longitudinal pattern remains present in the granular layer of lobules VIII, IX, X. High AChE activity is found in the granular layer of flocculus and paraflocculus. Within the molecular layer AChE positive Golgi-cells can be demonstrated.

Acetylcholinesterase↗
PubMed1986

Immunogenic and antigenic epitopes of immunoglobulins. XVIII. Subpopulations of human lambda chains defined with a panel of monoclonal antibodies.

Following immunization with various lambda Bence-Jones proteins, over 100 hybridomas were established. A majority of the monoclonal antibodies (McAb) produced were demonstrated to recognize epitopes common to all lambda chains or unique to the immunogen. Twenty-nine McAb exhibited profiles of 'restricted' reactivity. Analysis with a panel of serologically defined antigens allowed McAb recognizing the lambda II subgroup to be identified. Other McAb recognized epitopes selectively expressed by lambda II and lambda III subgroup proteins. A further twenty-one McAb exhibited individual specificity profiles, some of which detect minor lambda chain subpopulations. Several of these McAb have potential for analysis of the clonality of specific antibody responses and for detecting monoclonal B-cell proliferations.

Antibodies, Monoclonal↗
PubMed1986

Natural killer cell activity and head and neck cancer: a clinical assessment.

In 127 patients with squamous cell carcinoma of the upper aerodigestive system, an assessment of natural killer (NK) cell function was performed. The mean lytic unit (LU) value of this cancer population was noted to be less than the mean value of 67 age-matched controls assessed concurrently. The major determinant of cytolytic function was related to the growth pattern of the tumor. Increased NK cell function was observed in patients with lesions that were more locally or regionally aggressive, i.e., that infiltrated surrounding anatomic structures. The magnitude of NK cell response also correlated with increased amounts of circulating IgG immunoglobulin to herpes simplex virus-type 1-associated antigens; elevated IgG levels were also associated with locally aggressive lesions. The clinical significance of NK cell activity in these patients is shown by its relationship to disease-free prognosis. Patients with elevated NK activity followed for a mean of 12 months had an improved disease-free survival as compared to the survival of the remaining population. Furthermore, NK LU values were not reflected in standard staging methods, which suggests that the measurement of NK cell function represents an independent prognostic parameter in the patient with head and neck cancer.

Adult↗
PubMed1986

General surgery in adult hemophiliacs.

From 1976 to 1984, 23 operations were performed on 22 patients with hemophilia (18 patients with factor VIII and four with factor IX deficiency). Elective procedures included resection of abdominal aortic aneurysm, liver transplantation, vagotomy/pyloroplasty, insertion of Mousseau-Barbin tube, colectomy, cholecystectomy, inguinal herniorrhaphy (four patients), colonoscopy/polypectomy, mediastinoscopy, arteriovenous fistula for dialysis, anal fistulectomy, and miscellaneous skin and soft-tissue procedures (five patients). Emergency operations were appendectomy (two patients), repair of bleeding liver biopsy site, and repair of an incarcerated inguinal hernia. There were two deaths (9%) within 30 days of operation, neither directly caused by the coagulopathy. Four patients had bleeding after surgery, which was treated with additional cryoprecipitate or factor concentrate. There were no nonhemorrhagic complications. Before operation, appropriate replacement therapy with factor VIII concentrate, cryoprecipitate, or fresh-frozen plasma was provided. Coagulation factor levels were measured before operation and monitored daily after operation. Generally, factor levels were raised to at least 1.0 U/ml and maintained at greater than 0.5 U/ml for 7 to 14 days after operation. However, when patients were treated with fresh-frozen plasma, plasma exchange was performed and factor levels of approximately 0.35 U/ml were achieved before surgery. We conclude that operations in patients with hemophilia can be accomplished safely with careful monitoring of coagulation factor levels and appropriate replacement therapy.

Adolescent↗
PubMed1986

Dark adaptation in age-related maculopathy.

Dark adaptation was measured for patients with age-related maculopathy (ARM) and for age-matched controls; green and red test stimuli were flashed 15 degrees from the fovea to examine differential effects of ARM on rod and cone functions, respectively. The ARM patients showed decreases in sensitivity for both rods and cones (0.5-1.5 log units) and an increased time constant of recovery for rod function. After 20 min in the dark, sensitivity to both red and green stimuli was depressed at the fovea and at 5, 10, 15 and 25 degrees eccentric to the fovea. The greatest sensitivity loss was found in the macular area (fovea and 5 degrees eccentric). Our data suggest that the ARM patients have an abnormality in both rod- and cone-adaptation systems over a relatively large retinal area which extends beyond the zone of visual field abnormality.

Age Factors↗
PubMed1985

Infectious and bleeding complications in patients with glycogenosis Ib.

Clinical, hematologic, and immunologic findings were reviewed in 21 patients with glycogenosis Ib. Fifteen of the patients suffered from moderate to severe bacterial infections. Ten patients had excessive epistaxis or bleeding from surgical sites, and eight suffered oral and anal mucosal ulceration. Sixteen of 21 patients exhibited chronic neutropenia associated with abnormalities in myeloid maturation and decreases in the bone marrow storage and peripheral marginating pools. Diminished neutrophil motility was documented in 14 of 15 patients tested, and adherence was decreased in three patients studied. Neutrophil microbicidal activity, reduction of nitroblue tetrazolium, and ingestion were normal in all patients tested. Bleeding times were prolonged in five of eight patients, and results of platelet function studies were abnormal in five individuals. Excessive bleeding in patients with glycogenoses Ia and Ib are similar and may be secondary to the functional deficiency of glucose-6-phosphatase. However, neutropenia, neutrophil dysfunction, and the resulting infectious complications are specific for Ib disease and may be related to abnormal glucose-6-phosphate transport.

Adolescent↗
PubMed1985

Screen design and visual evoked potentials.

In this paper we present a method to complement the sophisticated mathematical analyses on screen designs. The use of an objective measure of screen "goodness" is employed, namely, the Visual Evoked Potential (VEP) of the humans performing the test. After the screen is designed, the text on the screen is transformed into an intensity pattern using a recursive algorithm. This intensity pattern is used as a stimulus to obtain wave forms from the scalp of the subject, and the wave forms are analyzed as to their frequency content. A 2-D Fourier transform of the screen design is performed and the frequency components of the power spectrum are compared to the frequency components of the wave form. Our results indicate that when a "balanced" and well-designed screen is used as a stimulus, the second harmonic of the VEP wave form is always smaller than the first harmonic. The implications of such an analysis are discussed.

Adult↗
PubMed1985

Reduction in type A behavior in healthy middle-aged American military officers.

One hundred eighteen senior officer-students of the U.S. Army War College who were healthy but exhibited type A behavior volunteered to be randomly selected and enrolled into (1) a section of 62 officers who received group type A behavior counseling for 9 months and (2) a control section of 56 officers who received no counseling of any kind. Marked or profound reduction in type A behavior at the end of 9 months was observed in 41.9% of the 62 participants who initially were enrolled to receive type A counseling; marked or profound reduction in type A behavior, however, was observed in only 8.9% of the 56 initially enrolled control subjects. No adverse effects on the military leadership qualities of type A counseled participants were observed by their classmates. Serum total cholesterol and plasma high-density lipoprotein (HDL) cholesterol measurements were obtained monthly. The serum cholesterol of the total cohort of subjects rose significantly during a month of considerable emotional tension and stress. Those subjects who underwent a profound reduction in the intensity of their type A behavior pattern also exhibited a significantly lower serum cholesterol value as the study continued than those subjects who exhibited no change in their type A behavior. No significant changes in plasma HDL cholesterol concentrations were observed in the total cohort during the above-mentioned period of stress, nor were any differences in this particular measurement noted between the type A counseled and the control participants.

Adult↗
PubMed1985

Psychosocial adjustment of burn survivors.

The purpose of this study was to assess the magnitude and predictors of psychosocial adjustment in burn victims. It was postulated that once individuals sustain a burn, their long-term psychosocial adjustment is a function of their present coping responses, social resources, burn severity and time since burn. It was expected that these variables could also be used to identify individuals at risk for psychosocial maladjustment. A historical cohort analytical survey of 340 randomly selected adults and the mothers of 145 children who had sustained either major or minor burns during the past 12 years were administered the Coping Scale, Participation in Social and Recreational Activities Index, Social Support and the Psychosocial Adjustment to Illness Scale. The children's mothers also completed the Family Environment Scale and the Child Behaviour Checklist. In summary, the variance in psychosocial adjustment among adults was related to unemployment, loss of occupational status, avoidance coping, and little involvement in recreational activities. Together, these variables explained 40 per cent of the variance in psychosocial adjustment. Severity of the burn and time since the burn were not related to psychosocial adjustment. The prevalence of psychosocial maladjustment among the adults was 10 per cent and 15.7 per cent among children. Psychosocial adjustment among children was not related to the severity of the burn. The less adjusted children could be distinguished from adjusted children on the basis of their mothers' adjustment and methods of coping. The findings tended to refute the commonly held view that post-burn adjustment is associated with burn severity and suggests psychosocial adjustment is a function of both coping responses and social resources.

Achievement↗
PubMed1985

An application of social learning methods in a residential programme for young offenders.

The application of behavioural principles to working with young offenders has been extensive in the U.S.A. in recent years with the development of the Achievement Place family group home programme a significant feature. Developments in the United Kingdom have been more limited, with no published accounts other than very partial replications of the Achievement Place approach. This paper describes the development of a partial replication of the Achievement Place approach in Unit One, a community based residential programme for young offenders in South East London. The Unit One programme incorporates a token economy, a school programme, teaching interactions and self-government. The paper describes successful outcomes for five out of eight of the delinquents first admitted to the programme, and identifies some of the factors associated with success. It also describes two process research projects evaluating effectiveness of training in social reinforcement for residential care staff, and in training teachers working with Unit One youth's to make effective demands for compliance. The paper concludes by highlighting problems in attempting a partial replication of the Achievement Place approach.

Adolescent↗
PubMed1985

Influence of protein composition and hydrolysis method on intestinal absorption of protein in man.

An intestinal perfusion technique has been used in normal human subjects to investigate the influence that starter protein composition and hydrolysis procedure have on absorption of amino acid residues from partial enzymic hydrolysates of whole protein. Five starter proteins were studied. Three (egg albumin, casein/soy/lactalbumin, and lactalbumin) were hydrolysed by papain, a second lactalbumin starter protein, and a meat/soy/lactalbumin blend were hydrolysed by a porcine pancreatic enzyme system. Irrespective of starter protein composition or hydrolysis method used, four amino acid residues (threonine, glutamic acid, phenylalanine, and histidine) were absorbed significantly faster from all hydrolysates compared with absorption from their equivalent free amino acid mixtures. In contrast, both starter protein composition and hydrolysis method influenced absorption characteristics of up to nine other amino acid residues.

Adult↗
PubMed1985

A retrospective-prospective study of medication errors: basis for an ongoing monitoring program.

Medication error surveillance is an important component of the quality assurance program of any hospital. The present study was undertaken in an attempt to determine the reliability of data collected retrospectively on medication error forms, as compared to data obtained from a prospective observational study within the same hospital. The results indicate that for many parameters reasonably reliable information can be obtained from voluntarily submitted error reports. Other observations made during the study were also useful to both the nursing and pharmacy departments in their efforts to minimize the occurrence of errors. Based on the information provided by this study, a more formalized medication error surveillance program has been established and a number of changes in the drug distribution and administration systems have been proposed.

Hospital Bed Capacity, 500 and over↗