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Biomedical subjects

J Evans

Publications and source records attributed to J Evans.

At least 253 records · Page 14Linked to original sources
PubMed1996

Is the incidence of registrable age-related macular degeneration increasing?

AIMS/BACKGROUND: Age-related macular degeneration (ARMD) is a growing public health problem in Britain; currently its aetiology is unclear. The aim of this study was to test the hypothesis that the age specific incidence of blinding ARMD has increased in Britain in the past 50 years, using data on cause of visual loss in people registered as blind, published every 10 years since 1950. METHODS: Data were abstracted from published sources for the years 1950, 1960, 1970, and 1980. Data for the standard year, 1990, were provided in a database from the Office of Population Censuses and Surveys. The numbers of new registrations attributed to ARMD per head of population were compared with registrations for cataract, glaucoma, and optic atrophy. Indirect standardisation was used to control for changes in the age structure of the population over time. RESULTS: After controlling for changes in the age structure of the population, registration rates for all causes, cataract, glaucoma, and optic atrophy have decreased while registrations attributed to ARMD have increased in the order of 30-40%. CONCLUSIONS: These findings are compatible with the hypothesis that the incidence of ARMD is increasing in Britain. It is difficult to exclude potential sources of bias in these data, however, particularly with respect to classification and coding of cause; more reliable population based data on ARMD in Britain are needed.

Blindness↗
PubMed1996

Pictorial review: the radiological spectrum of vertically-acquired HIV infection.

Anonymous antenatal and newborn screening demonstrates a positive HIV seroprevalence of one in 400 in areas of inner city London. European Collaborative Study data show a vertical transmission rate of 15% and suggests that 23% of infected children will develop clinical manifestations of AIDS before reaching 1 year of age [1], meaning that recognition of the radiological findings in vertically-acquired HIV is important. 75 serial cases of vertically-acquired HIV (age range 6 weeks to 12 years, mean age 35 months) presenting to a national referral centre over 48 months were reviewed; the radiographic findings we describe constitute a core of typical abnormalities together with a selection of the rarer manifestations of vertically-acquired HIV.

AIDS-Related Complex↗
PubMed1996

Influence of fixation accuracy on threshold variability in patients with open angle glaucoma.

PURPOSE: To evaluate the contribution that fixation errors make to the overall variability of perimetric responses in patients with glaucoma. METHODS: Frequency of seeing curves were established, with and without fixation error correction, at two locations in each of 14 patients with glaucoma and good visual acuity. One location corresponded to a relatively normal region of the visual field, whereas the second corresponded to a region in which there was a sensitivity deficit. All patients had an acuity of better than 20/63 (except one whose acuity was 20/100). The locations of the first and fourth Purkinje images of a collimated infrared source were used to give a measure of eye position, during each stimulus presentation (accuracy 10 minutes of arc). RESULTS: Considerable variation was found in patient fixation accuracy. In the worst case, fixation was within 30 minutes of the target in only 7% of presentations whereas in the best, it was within this range in more than 60%. No relationship was found between accuracy of fixation and extent of loss. The gradient of the frequency of seeing curve was found to be shallow at regions of reduced sensitivity, a finding that supports the recognized relationship between variability and sensitivity deficit. A recalculation of the frequency of seeing curves, using only those responses in which the patient's fixation was within a specified range ( < 60 minutes of arc), did not show a meaningful reduction in variability at either location. CONCLUSIONS: It is concluded that fixation errors, though contributing to variability, are not the major cause of the increased variability seen at locations with reduced sensitivity.

Aged↗
PubMed1996

Lymphatic and venous function in lipoedema.

Lipoedema is a common but infrequently recognized condition causing bilateral enlargement of the legs in women. Although generally considered to be the result of an abnormal deposition of subcutaneous fat with associated oedema, the precise mechanisms responsible for oedema formation have yet to be fully established. In order to evaluate the possible role of lymphatic or venous dysfunction in the pathogenesis of lipoedema, 10 patients were investigated by photoplethysmography (venous function) and quantitative lymphoscintigraphy (lymphatic function). The results were compared with those from patients with primary lymphoedema and those from healthy volunteers. The results demonstrated minor abnormalities of venous function in only two patients. One patient had moderately impaired lymphatic function in both legs and seven patients had a marginal degree of impairment in one or both legs. However, in none of these cases did the impairment attain the low levels seen in true lymphoedema. Lipoedema appears to be a distinct clinical entity best classified as a lipodystrophy rather than a direct consequence of any primary venous or lymphatic insufficiency.

Adipose Tissue↗
PubMed1996

Relationship of ethnicity and gender to schizophrenia and pharmacology of neuroleptics.

There is considerable heterogeneity in the psychopathology of schizophrenia and the response to neuroleptic treatment, at least some of which may result from ethnicity and gender differences among subjects. We review the literature relevant to ethnic and gender differences in psychopathology and neuroleptic response in schizophrenia. Studies reveal several diagnosis- and treatment-related differences in schizophrenia among different ethnic and gender groups. Some of these differences might be biological in origin, others due to cultural or environmental factors. In studies conducted in our center, we found no differences in psychopathology or amount of neuroleptic therapy between African-American and Caucasian patients. We did note that African-American patients in our sample had a somewhat greater risk of developing tardive dyskinesia than their Caucasian counterparts. The incidence of tardive dyskinesia was similar for males and females. Our studies of neuroleptic-induced tardive dyskinesia were restricted to patients over age 45, though there were no ethnic or gender differences in the daily neuroleptic dose. Future work in this area should carefully compare ethnic and gender differences in treatment response.

Adult↗
PubMed1995

Correlation of retinopathy of prematurity in fellow eyes in the cryotherapy for retinopathy of prematurity study. The Cryotherapy for Retinopathy of Prematurity Cooperative Group.

OBJECTIVE: To examine the similarity of extent (sectors) and severity (stage) of acute-phase retinopathy of prematurity (ROP) between fellow eyes and the concordance of cicatricial outcomes at age 1 year of eyes that did not develop threshold disease. METHODS: Four thousand ninety-nine infants with birth weights of less than 1251 g who participated in a natural history segment of the Cryotherapy for Retinopathy study underwent biweekly eye examinations from 4 to 6 weeks after birth until retinal vasculature was complete or until ROP regressed or reached threshold severity. Eyes were categorized as follows: (1) no ROP, (2) less than prethreshold ROP, (3) prethreshold ROP, (4) threshold ROP, and (5) unable to determine. The presence and stage of ROP residua in fellow eyes were evaluated at 12 months. RESULTS: Acute-phase ROP status between 32 and 42 weeks postconceptional age showed a high degree of correspondence between fellow eyes in severity (stage) and location (zone) of ROP, presence of plus disease, and sectors of stage 3 retinopathy. More variability between eyes was seen when cicatricial status at age 1 year was examined. This higher variability was evident even though results from patients with threshold ROP (many of whom underwent cryotherapy) were excluded. CONCLUSION: The usual course of ROP during its acute phase is for fellow eyes to be very similar in ROP status. However, asymmetry between eyes is not unusual in eyes with posterior pole residua of ROP.

Acute Disease↗
PubMed1995

Body size and parenting in eating disorders: a comparative study of the attitudes of mothers towards their children.

The present study aimed to redress the paucity of available information on the effects of eating disorders on patients' parenting capabilities and their children's development. Ten previous and/or current eating-disordered mothers and their children and 10 normal mothers and their offspring completed several rating scales and participated in a semistructured interview. The results indicated that both groups and their children displayed similar levels of satisfaction with their body sizes and perceived their current weights and shape with a similar degree of accuracy. These groups were, however, found to differ on the types of feeding employed during their children's infancy with the eating-disordered mothers choosing to schedule feed their babies, whereas the control mothers fed on demand. At least half the children of eating-disordered mothers were also described as suffering from emotional difficulties. Recommendations are made for increased availability of supportive and instructive facilities for these mothers, particularly during their nursing period.

Adolescent↗
PubMed1995

Purification and characterization of endogenous peptides extracted from HLA-DR isolated from the spleen of a patient with rheumatoid arthritis.

We have purified HLA-DR from the spleen of a patient with rheumatoid arthritis. The patient had Felty's syndrome and was heterozygous for the DR4Dw4 antigen. We have isolated endogenous peptides from purified HLA-DR molecules. The peptides were purified by reverse phase HPLC and the major peaks were subjected to N-terminal sequencing. The peptides were derived from a variety of proteins: human serum albumin, human erythroid protein 4.1, 60S ribosomal proteins L31 and L35, VCAM-1, human immunoglobulin lambda chain and cathepsin-S. A peptide corresponding to the sequence of human serum albumin (HSA) residues 106-120 was synthesized and shown to bind to HLA-DR4Dw4 (IC50 = 1.41 microM). We have confirmed and refined current ideas about the structural motif for the binding of peptides to HLA-DR and HLA-DR4Dw4.

Amino Acid Sequence↗
PubMed1995

Lyme disease.

In the United States, Lyme disease is the most common arthropod-borne infection. The majority of cases are reported from the Northeast, the Midwest, and California, which are areas with established foci of Borrelia burgdorferi. Advances in the understanding of the epidemiology of Ixodes ticks, the established vector for transmission of Lyme disease, provided strategies to reduce tick populations and the risk of acquiring disease. Genotypic diversity of subspecies of B. burgdorferi has been associated with differences in disease expression. New methods for detection of B. burgdorferi have expanded understanding of the pathogenesis of Lyme disease and provided clues into the mechanisms responsible for persistent symptoms. A safe vaccine for the prevention of Lyme disease in humans has been developed, and clinical vaccine efficacy trials are currently under way.

Arthritis, Infectious↗
PubMed1995

Spectral patterns and frequency response characteristics of arterial pressure in heart paced dogs.

The role of heart rate in buffering and/or generating aortic pressure (AP) oscillations that occur at rest and in response to oscillatory blood volume shifts was studied. Six supine dogs with chronic AV blockade were used to examine: 1) resting HR and AP spectra when the ventricular rate was controlled by atrial depolarization (natural sinus rhythm); 2) resting AP and stroke volume (SV) spectra when the heart was AV sequentially paced at 60, 120, and 180 bpm before and after ganglionic blockade; and 3) the frequency response characteristics of AP and SV to whole-body sinusoidal acceleration (+/- 2gz, 0.008-0.23 Hz) at each heart rate before and after ganglionic blockade. During atrial regulation of HR, the spectra of both AP and HR had dominant peaks located at the breathing frequency (0.2-0.4 Hz) and relatively smaller peaks centered at approximately 0.05 Hz. During constant heart rate pacing, the spectra of AP had a dominant component at approximately 0.05 Hz. The power of this component was: 1) larger than during atrial regulation, 2) increased with increasing pacing rate, and 3) abolished by ganglionic blockade. There was no effect of pacing rate or ganglionic blockade on SV spectra. During oscillatory acceleration, AP regulation in the heart paced dogs was frequency dependent. Regions of good regulation occurred below 0.016 Hz and above 0.1 Hz, and poor regulation between 0.035 and 0.075 Hz centered at approximately 0.05 Hz. The oscillations in the poor regulation region were enhanced by increased pacing rate. After ganglionic blockade, the frequency response of AP was primarily hydraulic (low-pass). The frequency response of SV had a neural component. We conclude that: 1) resting AP fluctuations at respiratory frequencies resulted from respiration-linked HR variation; 2) the 0.05-Hz fluctuations in AP during rest and the poor regulation of AP at 0.05 Hz during acceleration resulted from a peripheral vascular response that lagged disturbances by approximately 10 s; 3) HR regulation was important in minimizing AP variation in the 0.05-Hz region both at rest and during oscillatory acceleration; and 4) inotropic control of SV was an important component of AP regulation during low-frequency acceleration.

Acceleration↗
PubMed1995

Colour-coded duplex ultrasonography in selection of patients for transluminal angioplasty.

Transluminal angioplasty can be used to relieve symptomatic lower extremity arterial disease with minimal morbidity. This prospective study compares the accuracy of colour-coded duplex ultrasonography with intra-arterial digital subtraction angiography in selection of femoro-popliteal lesions for angioplasty. Isolated, short (< 6 cm) and haemodynamically significant stenosis (> 50% reduction in diameter) were considered for angioplasty. Colour-duplex selection and exclusion was in agreement with angiography in 68 out of 86 lower limbs (79%). The sensitivity, specificity, positive and negative predictive value of colour duplex compared with angiography yielded values of 60.9, 87.5, 60.9 and 85.7%, respectively. The discrepancy between colour duplex and digital subtraction angiography can be partly explained by the tendency of duplex to underestimate the severity and length of disease. It is concluded that colour-coded duplex can be used as a screening tool for lower extremity arterial disease to select appropriate lesions for endovascular procedures. The accuracy of duplex in the present study was not perfect and the decision for further intervention should be based on clinical grounds.

Angiography, Digital Subtraction↗
PubMed1995

Growth and detection of filamentous fungi in the BacT/Alert blood culture system.

Little is known about the behaviour of filamentous fungi in most blood culture systems, despite their increasingly recognised role in infections of immunocompromised hosts. The ability of the BacT/Alert system (Organon Teknika, Durham, North Carolina, USA) to detect the growth of 19 such fungi was examined. Eleven species grew and were detected rapidly; two species did not grow. Six species grew slowly, and were generally only recovered with terminal subculture after prolonged incubation. The CO2 production graph for some of these fungi showed a slow but steady rise, insufficient to cause the apparatus to signal positive. These results show that the BacT/Alert system may miss some fungi, either because of no growth in the medium or undetected slow growth. The latter problem could be overcome by prolonged incubation and terminal subculture when fungal infection is considered likely. Alteration of the signalling mechanism might permit earlier detection of some slow growing fungi.

Blood↗
PubMed1995

Pharmacology of montelukast sodium (Singulair), a potent and selective leukotriene D4 receptor antagonist.

Montelukast sodium (Singulair), also known as MK-0476 (1-(((1(R)-(3-(2-(7-chloro-2-quinolinyl)-(E)-ethenyl)phenyl)(3-2-(1- hydroxy-1-methylethyl)phenyl)propyl)thio)methyl)cyclopropane) acetic acid sodium salt, is a potent and selective inhibitor of [3H]leukotriene D4 specific binding in guinea pig lung (Ki 0.18 +/- 0.03 nM), sheep lung (Ki 4 nM), and dimethylsulfoxide-differentiated U937 cell plasma membrane preparations (Ki 0.52 +/- 0.23 nM), but it was essentially inactive versus [3H]leukotriene C4 specific binding in dimethylsulfoxide-differentiated U937 cell membranes (IC50 10 microM) and [3H]leukotriene B4 specific binding in THP-1 cell membranes (IC50 40 microM). Montelukast also inhibited specific binding of [3H]leukotriene D4 to guinea pig lung in the presence of human serum albumin, human plasma, and squirrel monkey plasma with Ki values of 0.21 +/- 0.08, 0.19 +/- 0.02, and 0.26 +/- 0.02 nM, respectively. Functionally, montelukast antagonized contractions of guinea pig trachea induced by leukotriene D4 (pA2 value 9.3; slope 0.8). In contrast, montelukast (16 microM) failed to antagonize contractions of guinea pig trachea induced by leukotriene C4 (45 mM serine-borate), serotonin, acetylcholine, histamine, prostaglandin D2, or U-44069. Intravenous montelukast antagonized bronchoconstriction induced in anesthetized guinea pigs by i.v. leukotriene D4 but did not block bronchoconstriction to arachidonic acid, histamine, serotonin, or acetylcholine. Oral administration of montelukast blocked leukotriene D4 induced bronchoconstriction in conscious squirrel monkeys, ovalbumin-induced bronchoconstriction in conscious sensitized rats (ED50 0.03 +/- 0.001 mg/kg; 4 h pretreatment), and also ascaris-induced early and late phase bronchoconstriction in conscious squirrel monkeys (0.03-0.1 mg/kg; 4 h pretreatment). A continuous i.v. infusion of montelukast (8 micrograms.kg-1.min-1) resulted in a 70% decrease in the peak early response and a 75% reduction of the late response to ascaris aerosol in allergic conscious sheep. Montelukast, a potent and selective leukotriene D4 receptor antagonist with excellent in vivo activity is currently in clinical development for the treatment of asthma and related diseases.

Acetates↗
PubMed1995

Control of expiratory time in conscious humans.

Combinations of 17 normal awake humans breathed mildly hyperoxic and hypercapnic gas mixtures via a pneumotachograph into an open circuit. Respiratory pattern was measured for each breath in real time by computer. Use of computer-controlled auditory feedback at a constant end-tidal PCO2 (PETCO2) allowed prolonged changes of 1) inspiratory time (TI) at constant inspired tidal volume (VTI), 2) VTI up and down in repeated steps at constant TI, and 3) expiratory time (TE) at constant VTI. The remaining variables were free to be determined by the subjects' automatic respiratory control mechanisms. We showed that TE changed in parallel with the change in TI despite constant VTI, TE did not change in response to step changes in VTI at constant TI, and large changes in TE had no influence on the subsequent TI, but VTI increased slightly as TE lengthened despite clamping. Time for expiratory flow (TE--end-expiratory pause) changed in parallel with TE in all protocols. Thus, in conscious humans, inspiratory timing has a direct influence on expiratory timing, independent of volume change and chemical drive, but expiratory timing has no influence on the inspiratory timing of the subsequent breath but has a small influence on volume.

Adult↗