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Biomedical subjects

G Smith

Publications and source records attributed to G Smith.

At least 379 records · Page 21Linked to original sources
PubMed1995

Tumour necrosis factor, interleukin-6 and C-reactive protein in patients with louse-borne relapsing fever in Ethiopia.

The serum concentrations of tumour necrosis factor (TNF), interleukin-6 (IL-6) and C-reactive protein (CRP) were studied in 25 patients with louse-borne relapsing fever, to evaluate their association with the level of bacteraemia, anti-borrelia chemotherapy and the presence of a Jarish-Herxheimer reaction (JHR). Although there was an association between the level of bacteraemia and the development of JHR and complications during treatment, TNF, IL-6 and CRP concentrations were not associated with the JHR. TNF concentrations increased after the administration of antibiotics and remained high for 24 h. IL-6 was elevated on admission but soon decreased. CRP was high on admission and remained so throughout the illness. The observed elevations in TNF, IL-6 and CRP may be associated more with the administration of antibiotics than with the presence of a JHR.

Adolescent↗
PubMed1995

Incidence of hypertrophic cardiomyopathy in hypothyroidism.

In 13 consecutive severely hypothyroid patients no sign of endocrine cardiomyopathy in the form of asymmetric septal hypertrophy (ASH) could be disclosed by M-mode and two-dimensional (2D) echocardiography on examination prior to thyroxine replacement therapy. In previous investigations ASH was demonstrated to be almost invariably present in untreated hypothyroidism irrespective of thyrotropin levels. Consequently application of positive inotropic and afterload reducing agents that may invoke deleterious effects in ASH has been considered hazardous in hypothyroidism even when indicated by concurrent other heart disease. Determination of exact confidence limits reveals that the proportional incidence of hypothyroid hypertrophic cardiomyopathy could not exceed 24.7% with 95% probability. We conclude that ASH is not necessarily inherent in hypothyroidism.

Adult↗
PubMed1995

Silent myocardial ischemia in hypothyroidism.

In some patients with severe hypothyroidism thyroxine replacement therapy precipitates or aggravates angina pectoris, whereas in other patients angina pectoris is ameliorated or even disappears. The reason for this paradox is unknown. It has been attributed either to reversible endocrine cardiomyopathy in the form of asymmetric septal hypertrophy (ASH) or reversible anatomical narrowing of the coronary arteries. The results of a recent investigation, in which myocardial performance was surveyed by radionuclide ventriculography throughout early thyroxine replacement therapy in severe hypothyroidism, were compatible with the presence of reversible coronary dysfunction rather than of ASH. The aim of the present investigation was to confirm these findings. In six severely hypothyroid patients, without echocardiographic evidence of ASH or evidence of concomitant coronary artery disease (CAD), exercise and redistribution tomographic myocardial thallium-201 imaging (SPECT) was performed before thyroxine replacement therapy and repeated after 10 days and again after 2 months during therapy. In four patients substantial regional perfusion defects were demonstrated after exercise that were normalized at rest both before, and in one subject also after 10 days, on thyroxine. With restoration of euthyroidism, exercise and redistribution SPECT were normal in every patient. Determination of exact confidence limits reveals that the proportional incidence of myocardial perfusion defects in hypothyroidism, indicating myocardial ischemia, will at least be 22% with 95% probability. Despite the relatively low specificity of SPECT it seems pertinent to conclude that impaired myocardial perfusion as assessed by SPECT probably is due to reversible coronary dysfunction inherent in the hypothyroid state, and that this is not an infrequent manifestation of severe hypothyroidism.

Adult↗
PubMed1995

Useful variations of the Badal Optometer.

The simple Badal Optometer consists of a movable target and a fixed positive power lens placed at its focal distance away from the eye. The perceived angular size of the target is independent of target position and the power scale is linear. Limitations of the simple Badal Optometer include restriction of negative (myopic) ocular vergence range, the need for targets to be small, and the problem of "proximal" accommodation. We describe two modifications to the Badal system in which these limitations may be overcome by the use of a movable auxiliary optical system. In one modification, the movable auxiliary system consists of a target and positive lens which together may provide a virtual "target" for the Badal lens and thus increase the negative range. In the second modification, the Badal lens is positioned as it would normally be, but the target is an image of a distant stimulus created by the auxiliary lens. The target position (and hence the ocular vergence) is changed by moving the auxiliary lens. The distant target eliminates the proximal accommodative stimulus and allows spatial detail near the resolution limit to be displayed.

Accommodation, Ocular↗
PubMed1995

Absorption of ammonia by high water content hydrogel lenses: an inexpensive method of analysis.

Few studies have been done on the absorption and release of chemical vapors by high water content hydrogel lenses. In this study we investigated the absorption of ammonia vapors by this type of contact lens (CL). Ten high water content hydrogel lenses were exposed to vapor generated in a cuvette by 1 drop of aqueous ammonia. The contact lens was transferred to a 0.9% saline solution containing a colorometric indicator for ammonia and the amount of ammonia released into the saline was measured. We found that significant quantities of ammonia were absorbed into the lenses and the relation between average concentration of ammonia vapor and amount absorbed per contact lens was nearly linear from 50 parts per million (ppm) to 250 ppm ammonia vapor. For concentrations greater than 250 ppm there appears to be a saturation effect. Our findings indicate that high water contact lenses will absorb ammonia and release it into a solution similar to tears.

Absorption↗
PubMed1995

Defining a quality strategy for learning disability services. Lifecare NHS Trust establishes its core values for care and quality.

Describes how Lifecare NHS Trust established core values and an ISO 9000 quality framework as the foundation for patient care quality improvement. Discusses a procedural approach to ensure that Lifecare defines clearly the requirements of the management of every aspect of its care system. Presents a framework for total quality management and process improvement of care delivery.

Efficiency, Organizational↗
PubMed1995

Peroxides in human leucocytes in acute septic shock: a preliminary study of acute phase changes and mortality.

Peroxidation by peripheral blood leucocytes was measured in 15 patients in acute septic shock and 15 uninfected controls, using the probe dichloroflorescein. Mortality in septic subjects was 40%. In 14 of 15 patients from whom serial samples were analysed, periods of increased oxidative activity were detected. Increased peroxidation occurred early in the sequence of clinical changes, at the same time as increases in temperature, blood pressure and C-reactive protein. Peak peroxide production preceded increases in acute phase reactants and changes in leucocyte distribution. Mean peroxide production in leukocytes from patients who died was significantly higher (P < 0.001) than paired controls, and greater (P < 0.05) than peroxide production in patients who survived. The in vitro oxidative response to endotoxin was upregulated in infected patients. This supports the hypothesis that systemic mediators and leucocyte-derived reactive oxygen are involved in the vascular and organ damage associated with fatal septic shock.

Acute-Phase Reaction↗
PubMed1995

The immunoglobulin VH gene, VH4-21, specifically encodes autoanti-red cell antibodies against the I or i antigens.

Most autoanti-red cell antibodies found in patients with cold agglutinin disease are specific for the I or i carbohydrate antigenic determinants. However, antibodies specific for other antigens such as Pr or Sa can also be found, and these are identified by their pattern of reactivity with enzyme-treated red cells. Recently, it has been shown that the vast majority of anti-Ii antibodies react with a monoclonal anti-idiotypic antibody (9G4); this reactivity arises from restriction of the immunoglobulin heavy chains used to encode the antibodies to a single VH4-21 gene, VH4-21. The 9G4 antibody appears specific for this gene product, and we have used it to analyse VH4-21 gene involvement in encoding a spectrum of red cell antibodies of various specificities. The results support the strong association between usage of this gene and anti-Ii specificity and indicate that it is not generally used by other specificities. In particular, it is striking that the unsubstituted type 2 oligosaccharide antigens (I and i) induce a highly restricted autoantibody response very different from that induced by the sialylated type 2 antigens (Sia-b, -1 and 1b). The 9G4 antibody therefore provides a simple tool for discrimination between these autoanti-red cell antibodies, which should be of use in red cell serology.

Adult↗
PubMed1995

The effect of extracorporeal piezoelectric lithotripsy on the contractility of the human pelvicalyceal system.

OBJECTIVE: To assess the effect of extracorporeal piezoelectric lithotripsy (EPL) on the contractility of the human pelvicalyceal system. PATIENTS AND METHODS: Contractions of the pelvicalyceal system were measured in 12 patients (mean age 55 years) before and after EPL. Pelvicalyceal pressure was measured via a Cope nephrostomy tube which had remained in situ following stone debulking procedures days or weeks earlier. All patients were treated using a Wolf Piezolith 2300 lithotripter. RESULTS: The pelvicalyceal systems of two patients were acontractile before and after treatment. Immediately after treatment, contractions were completely abolished in eight of the remaining 10 systems, and reduced in frequency in the other two. All 10 systems regained contractions 24 h after treatment. CONCLUSION: Piezoelectric lithotripsy temporarily abolishes upper urinary tract motility.

Female↗
PubMed1995

Serum IgG response to Burkholderia cepacia outer membrane antigens in cystic fibrosis: assessment of cross-reactivity with Pseudomonas aeruginosa.

Burkholderia cepacia (Pseudomonas cepacia) is now recognised as an important pathogen in cystic fibrosis patients, and several reports have suggested that sputum-culture-proven colonisation occurs despite the presence of specific antibody. In an attempt to establish the use of antibody studies as diagnostic and prognostic indicators of B. cepacia infection, we have examined the IgG response to B. cepacia outer membrane proteins and lipopolysaccharide in patients also colonised with P. aeruginosa. The B. cepacia strains were grown in a modified iron-depleted chemically defined medium and outer membrane components examined by SDS-PAGE and immunoblotting. IgG antibodies were detected against B. cepacia outer membrane antigens, which were not diminished by extensive preadsorption with P. aeruginosa. The response to B. cepacia O-antigen could be readily removed by adsorption of serum either with B. cepacia whole cells or purified LPS, whereas we were unable to adsorb anti-outer membrane protein antibodies using B. cepacia whole cells. The inability to adsorb anti-outer membrane protein antibodies using B. cepacia whole cells maybe due to non-exposed surface epitopes. Several B. cepacia sputum-culture negative patients colonised with P. aeruginosa had antibodies directed against B. cepacia outer membrane protein. this study suggests that there is a specific anti-B. cepacia LPS IgG response, which is not due to antibodies cross-reactive with P. aeruginosa. Our studies indicate that much of the B. cepacia anti-outer membrane protein response is specific and not attributable to reactivity against co-migrating LPS.

Adolescent↗
PubMed1995

Familial dilated cardiomyopathy in the United Kingdom.

OBJECTIVES: To determine the frequency and mode of inheritance of familial dilated cardiomyopathy in the United Kingdom. BACKGROUND: Two recent prospective studies have suggested that familial forms of dilated cardiomyopathy are common but have been limited by selective screening methods, inadequate diagnostic criteria, and low rates of ascertainment. METHODS: Prospective screening study of 236 relatives from 40 families of patients with dilated cardiomyopathy. Screening consisted of clinical examination, 12 lead electrocardiogram, and two-dimensional Doppler echocardiography. Relatives with systemic hypertension and other cardiac diseases were excluded from the study. All echocardiograms were performed by an experienced echocardiographer who was blinded to clinical information. Relatives were classified as having dilated cardiomyopathy, left ventricular enlargement (method of Henry), depressed fractional shortening, or as being normal. Relatives with abnormal investigations underwent further evaluation as appropriate. RESULTS: Twenty five cases of dilated cardiomyopathy were identified and came from 10 (25%) of the 40 families screened. Pedigree analysis was most consistent with autosomal dominant inheritance and variable penetrance (65-95%). Of the remaining apparently healthy relatives, 37 (18%) were found to have left ventricular enlargement and nine (4%) depressed fractional shortening; these values were significantly higher than those observed in 239 healthy controls (24 (10%), P = 0.02 and one (0.4%), P = 0.01, respectively). CONCLUSIONS: Patients with dilated cardiomyopathy commonly have an affected family member and a high proportion of apparently healthy relatives with minor echocardiographic abnormalities. Segregation analysis suggests that familial dilated cardiomyopathy is the result of the transmission of a rare autosomal dominant gene. Further studies are currently underway to characterise the molecular basis of familial dilated cardiomyopathy and identify early disease within these families.

Adolescent↗
PubMed1995

The gastrointestinal tract after anaesthesia.

Gastrointestinal tract motility may be reduced markedly after surgery with delay in gastric emptying. these alterations are induced partly by surgery, partly by the residual effects of anaesthetic agents, and particularly by opioids administered for post-operative pain relief. These changes may be antagonized to a certain extent by administration of prokinetic agents such as cisapride. Post-operative ileus reduces the rate of mobilization and may also reduce or delay absorption of drugs administered by the gastrointestinal tract. Furthermore, post-operative nausea and vomiting, multi-factorial in aetiology, may ensue and also be responsible for delayed mobilization, subjective discomfort and delay in administration of oral agents post-operatively. A serious problem may be leakage from bowel anastomoses. Although the causes are primarily surgical, an increase in bowel contractility may be deleterious and it has been suggested that neostigmine and morphine may be implicated in anastomotic dehiscence.

Anesthesia↗
PubMed1995

Using computers to test visual acuity.

BACKGROUND: This paper describes a computer-generated acuity test that can be produced on IBM compatible equipment in the Windows 3.1 environment. METHODS: The acuity test was applied to 14 observers using two psychophysical methods (staircase and method of constant stimuli [MOCS]) to determine the validity and reliability of the outcomes. Comparisons were made between test methods and a hard copy LogMAR chart using statistics suited to intra-class comparisons. The effect that screen luminance has on outcomes and hardware warm-up requirements were also considered. RESULTS: The computer staircase was found to provide a reliable estimate of acuity. The hard copy chart and computer staircase have an Intraclass Correlation Coefficient (ICC) of 0.98. The threshold derived from the different psychophysical methods is also highly correlated (ICC = 0.98). The monitor provides a stable luminance 30 minutes after a cold start, and a 1 logunit (10 times) change in screen luminance has little effect on outcomes. CONCLUSIONS: A computer-driven acuity staircase provides a good estimate of threshold if a 30-minute warm-up period is allowed to stabilize monitor luminance. It also gives a measure of variability. A staircase is adequate for clinical applications as it provides a reasonable compromise between test time and accuracy. An extra 30 seconds is needed to obtain a staircase result (compared with hard copy), which is offset by the provision of this error term.

Adult↗