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Biomedical subjects

S Wright

Publications and source records attributed to S Wright.

At least 181 records · Page 10Linked to original sources
PubMed1994

Endothelin in human congestive heart failure.

BACKGROUND: Although recent investigations report the elevation of plasma endothelin (ET) in congestive heart failure (CHF), it remains unclear if this elevation is that of the biologically active peptide ET-1 or of its precursor big-ET. Furthermore, it is unclear if such elevation is associated with increased myocardial ET and if the molecular form from cardiac tissue is altered ET. Last, it remains to be established whether circulating ET is increased at the earliest stage of CHF in patients with asymptomatic left ventricular dysfunction and correlates with the magnitude of ventricular dysfunction. METHODS AND RESULTS: The present study was designed to investigate concentrations and molecular forms of ET in plasma and cardiac tissue in healthy subjects and CHF patients with New York Heart Association (NYHA) class I through IV using cardiac radionuclide angiogram, cardiac myocardial biopsy, radioimmunoassay, gel permeation chromatography (GPC), and immunohistochemical staining (IHCS). Plasma ET was increased only in patients with moderate (NYHA class III) or severe (NYHA class IV) CHF compared with healthy subjects and individuals with asymptomatic (NYHA class I) or mild (NYHA class II) CHF. The elevation of circulating ET in CHF showed a negative correlation with left ventricular ejection fraction and cardiac index and a positive correlation with functional class and left ventricular end-diastolic volume index. GPC demonstrated that immunoreactive plasma ET was ET-1 in healthy subjects and both mature ET-1 and its precursor big-ET in severe CHF patients, with big-ET the predominant molecular form. Cardiac tissue concentrations and IHCS revealed ET presence in healthy atrial and ventricular tissue, which were not different in severe CHF. GPC revealed that the molecular form of cardiac ET was ET-1 in both healthy and CHF hearts. CONCLUSIONS: The present study establishes for the first time that the elevation of plasma ET in severe human CHF represents principally elevation of big-ET. Second, ET is present in healthy and failing myocardia, and its activity by both immunohistochemistry and radioimmunoassay is not changed in CHF. Furthermore, the elevated plasma ET is characteristic of severe CHF and not asymptomatic or mild CHF. In addition, the degree of plasma elevation of ET correlates with the magnitude of alterations in cardiac hemodynamics and functional class. The present study confirms and extends previous investigations of ET in human CHF and establishes the evolution of circulating and local cardiac ET in the spectrum of human CHF.

Chromatography, Gel↗
PubMed1994

Choice making to promote adaptive behavior for students with emotional and behavioral challenges.

Two analyses investigated the effects of choice making on the responding of elementary school students with emotional and behavioral challenges. In the first analysis, 2 participants were given choices from menus of academic tasks, all of which were pertinent to their educational objectives in English and spelling, respectively. Reversal designs showed that the choice-making conditions increased task engagement and reduced disruptive behavior for both students. An additional analysis was performed with a 3rd student in an effort to further distinguish the effects of choice making from preference. In this study, one of the no-choice phases was yoked to a previous choice-making condition. This analysis demonstrated that the choice-making condition was superior to baseline and yoked control phases as determined by levels of task engagement and disruptive behavior. The findings of the two analyses contribute information relevant to students with emotional and behavioral disorders, and to a growing literature on the desirable effects of choice making for students with disabilities and challenging behaviors.

Attention↗
PubMed1994

Relationship between pruritus, transepidermal water loss, and biochemical markers of renal itch in haemodialysis patients.

The pathogenesis of pruritus in patients undergoing chronic haemodialysis is unknown. Dryness of the skin is common in uraemic patients, and a correlation between xerosis and pruritus has been reported. Transepidermal water loss (TEWL) is a measure of cutaneous barrier function and also reflects skin water content. In this study the transepidermal water loss was measured at four sites pre- and postdialysis in 20 subjects undergoing chronic haemodialysis and in 16 healthy controls. Patients were weighed before and after dialysis and blood was taken for measurement of urea, creatinine, calcium, magnesium, phosphate and haemoglobin. All patients had parathyroid hormone measured within 3 months of the assessment. There was no significant difference in TEWL between patients and controls, with control values in general being between pre- and postdialysis rates of TEWL, and no correlation between TEWL and the presence or absence of pruritus. There was no significant differences between the pruritic and non-pruritic patients for any of the biochemical markers measured. Finally there was no significant correlation between the percentage water loss and TEWL. These findings indicate that pruritus of chronic haemodialysis is not related to abnormalities of cutaneous permeability.

Adult↗
PubMed1994

Secondary structure of amyloid beta peptide correlates with neurotoxic activity in vitro.

Amyloid beta peptide (A beta), the major protein constituent of senile plaques in patients with Alzheimer's disease, is believed to facilitate the progressive neurodegeneration that occurs in the latter stages of this disease. Early attempts to characterize the structure-activity relationship of A beta toxicity in vitro were compromised by the inability to reproducibly elicit A beta-dependent toxicity across different lots of chemically equivalent peptides. In this study we used CD spectroscopy to demonstrate that A beta secondary structure is an important determinant of A beta toxicity. Solubilized A beta was maximally toxic when the peptide adopted a beta-sheet conformation. Three of the four A beta lots tested had a random coil conformation and were weakly toxic or inactive, whereas the single A beta lot exhibiting toxic activity at low peptide concentrations had significant beta-sheet structure. Incubation of the weakly toxic A beta lots in aqueous stock solutions for several days before use induced a time-dependent conformational transition from random coil to beta-sheet and increased A beta toxicity in three different toxicity assays. Furthermore, the secondary structure of preincubated A beta was dependent upon peptide concentration and pH, so that beta-sheet structures were attenuated when peptide solutions were diluted or buffered at neutral and basic pH. Our data could explain some of the variable toxic activity that has been associated with A beta in the past and provide additional support for the hypothesis that A beta can have a causal role in the molecular neuropathology of Alzheimer's disease.

Amyloid beta-Peptides↗
PubMed1993

Experimental challenge of sheep 18 months after vaccination with a live (S48) Toxoplasma gondii vaccine.

Sheep can be immunised against toxoplasma abortion with a live vaccine composed of S48 tachyzoites. In this study the immunity induced in sheep was examined 18 months after vaccination. Seventy-three sheep were divided into three groups. Group 1 was vaccinated and 18 months later, when they were 90 days pregnant, the 27 sheep were challenged orally with Toxoplasma gondii oocysts. These ewes produced significantly more live lambs, after a significantly longer gestation period, than the 34 unvaccinated, challenged ewes in group 2. In addition there was less placental damage and fewer lambs were born with antibody to the parasite in the vaccinated group than in group 2. The 12 ewes in group 3 served as unvaccinated, unchallenged control animals. The degree of protection induced by the S48 tachyzoites was as good 18 months after vaccination as previously observed six months after vaccination.

Abortion, Veterinary↗
PubMed1993

Breast milk from mothers of children with newly developed atopic eczema has low levels of long chain polyunsaturated fatty acids.

BACKGROUND: Infants at risk of atopic dermatitis have lower than normal levels of long chain polyunsaturated fatty acids. These fatty acids are normally present in substantial quantities in human breast milk. METHODS: Because of the equivocal evidence concerning the ability of breastfeeding to delay the onset or reduce the severity of atopic dermatitis, we have analyzed the fatty acid composition of breast milk from the mothers of children with newly developed disease with the use of gas chromatography. RESULTS: Breast milk lipids from mothers of children with newly developed atopic dermatitis had increased proportions of linoleic acid and significantly decreased proportions of its long chain polyunsaturated derivatives compared with a control group. The ratio of linoleic acid to the sum of its metabolites, gamma-linolenic acid, dihomo-gamma-linolenic acid, and arachidonic acid was 11.78 in the atopic group and 9.02 in the control group (p < 0.01). CONCLUSIONS: These results are consistent with previous findings of an abnormal fatty acid status in atopic subjects and may account for some of the inconsistent results from studies of the effect of breastfeeding on the subsequent development of atopic dermatitis. We conclude that further studies to examine the effects of supplementation of the diet of breastfeeding mothers with long chain polyunsaturates should be done.

Adult↗
PubMed1993

Sequential Cotard and Capgras delusions.

We report sequential Cotard and Capgras delusions in the same patient, KH, and offer a simple hypothesis to account for this link. The Cotard delusion occurred when KH was depressed and the Capgras delusion arose in the context of persecutory delusions. We suggest that the Cotard and Capgras delusions reflect different interpretations of similar anomalous experiences, and that the persecutory delusions and suspiciousness that are often noted in Capgras cases contribute to the patients' mistaking a change in themselves for a change in others ('they are impostors'), whereas people who are depressed exaggerate the negative effects of the same change whilst correctly attributing it to themselves ('I am dead'). This explains why there might be an underlying similarity between delusions which are phenomenally distinct.

Adult↗
PubMed1993

A developmental study of specific spelling disability.

Previous studies have identified a group of individuals with specific problems in spelling, and compared them to a group with problems in reading and spelling. Those who are poor at reading and spelling are thought to have more severe underlying language problems. This study compared the cognitive abilities of three groups of children: one specifically spelling disabled, one spelling and reading disabled, and one control group without reading or spelling problems. The groups were identified at age 14. A five-year retrospective analysis of their performance revealed that both of the disabled groups had been significantly poorer than the controls, not only in spelling but also in reading. Both the disabled groups showed other signs often associated with dyslexia such as poor WISC-R Coding and Digit Span. Analyses of their spelling errors did not reveal the superior phonetic abilities which some other studies have found to differentiate specifically spelling disabled from reading + spelling disabled groups. The specific spelling disabled group did show some evidence of superiority in Verbal IQ subtests. These results are consistent with the idea that specific spelling disability is a residual problem of individuals who, possibly by means of underlying verbal strengths, have managed to compensate for earlier reading difficulties.

Achievement↗
PubMed1993

Deaths from volatile substance abuse in those under 18 years: results from a national epidemiological study.

The epidemiology of deaths from volatile substance abuse (VSA) in those under 18 years that occurred in the UK from 1981-90 is described. The analysis of deaths is based on a national register, which has information obtained from a regular survey of coroners, the Office of Population Censuses and Surveys, and a press clippings agency. Altogether 605 people under 18 died from VSA during this period. Seventy per cent of deaths occurred between the ages of 14 and 16. The largest number of deaths were attributed to butane gas lighter refills. There was a large north-south gradient in age specific mortality ratios (Scotland 180, south east England 87) and nearly four times as many deaths occurred in social class V compared with social class I. Deaths from VSA are an important and preventable cause of deaths in those under 18. Strategies aimed at prevention should include measures to reduce experimentation, intervention to reduce socioeconomic deprivation, and health education campaigns aimed at schools and parents.

Adolescent↗
PubMed1993

Face-processing impairments and the Capgras delusion.

Investigations of two cases of the Capgras delusion found that both patients showed face-processing impairments encompassing identification of familiar faces, recognition of emotional facial expressions, and matching of unfamiliar faces. In neither case was there any impairment of recognition memory for words. These findings are consistent with the idea that the basis of the Capgras delusion lies in damage to neuro-anatomical pathways responsible for appropriate emotional reactions to familiar visual stimuli. The delusion would then represent the patient's attempt to make sense of the fact that these visual stimuli no longer have appropriate affective significance.

Aged↗
PubMed1992

The pathophysiology of cardiorespiratory arrest and principles of post-resuscitation intensive care.

Oxygen supply to the tissues is dependent on both cardiac output (which is determined by blood volume and myocardial function) and the oxygen tension of arterial blood (which reflects respiratory status). Abnormalities of these parameters may occur individually or together to progress ultimately to combined cardiorespiratory collapse. Life support measures are then required to restore the oxygen supply to vital organs, such as the brain, heart, kidneys and liver while attempts to restore normal cardiorespiratory status are made. Survival following cardiorespiratory arrest is enhanced if resuscitation is promptly instituted by skilled resuscitators, and a clear understanding of the mechanisms of cardiorespiratory collapse are essential to the efficient management of these patients.

Arrhythmias, Cardiac↗
PubMed1992

Proof of differentiative mode of action of all-trans retinoic acid in acute promyelocytic leukemia using X-linked clonal analysis.

Using X-linked clonal analysis, mechanism of action of all-trans retinoic acid (ATRA) was sought in a 16-year-old female with relapsed clonally evolved acute promyelocytic leukemia (APL), who achieved complete remission. On ATRA, metamorphosis of peripheral blood leukemic promyelocytes to mature neutrophils was observed, despite the persistence of t(15;17) in 100% of bone marrow metaphases. DNA was extracted from fractionated serial blood specimens, collected at diagnosis, in first complete remission (CR), relapse, and during ATRA treatment. Using a phosphoglycerokinase (PGK) probe, the patient was heterozygous for both Bgl I and Bst XI PGK polymorphisms. Methylation analysis showed monoclonal leukemic promyelocytes with a polyclonal first CR achieved by standard chemotherapy. Subsequent examination, in relapse, of granulocytes appearing during ATRA treatment showed these to be monoclonal, proving these were derived from the neoplastic clone. The X-linked clonal analysis methodology has provided in vivo evidence of cellular differentiation as the mechanism of action of ATRA. Parallel studies of cytogenetic and clonal analysis showed a regression of the t(15;17) cytogenetic abnormality and return of a polyclonal PGK methylation pattern in 5 weeks, indicating a repopulation of marrow by normal stem cells. As standard cytogenetic techniques are inappropriate for nondividing cells, X-linked clonal analysis provides a marker system to allow insight into mechanism of drug action in malignant hematologic disease.

Adolescent↗