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Biomedical subjects

M Summerfield

Publications and source records attributed to M Summerfield.

17 recordsLinked to original sources
PubMed1999

The relationship between personality and attainment in 16-19-year-old students in a sixth form college. I: Construction of the Student Self-Perception Scale.

BACKGROUND: Of the research that has been undertaken into the relationship between personality and attainment, relatively little exists relating to the 16-19 age range. In a substantive study examining the relationship between academic self-concept, attainment and personality in sixth form students, a first requirement was to design a self-perception instrument. AIMS: The psychometric element of the study aimed to construct a Student Self-Perception Scale (SSPS) that would be effective for students in the FE (further education) context. SAMPLES: The samples comprised a pilot sample of 152 students (aged 16-17 years from two sixth from colleges) and a main sample of 364 students (mean age, 16yrs 10mths, range 16:0 to 18:6 years, from one sixth form college). The main sample included similar numbers of male and female students (46% male, 54% female) and ethnic minority students comprised 14% of this sample. METHOD: An initial item pool of 88 four-point Likert type statements was compiled from comparable existing scales and from responses to a Student Induction Questionnaire. Item analysis was based on oblique factor analysis of the pilot sample responses, followed by cross-validation on the main sample to refine the scale structures. Construct validity was established from the substantive study, especially the Nowicki & Strickland (1973) locus of control results. RESULTS: Exploration of the four- and five-factor structures led to a final specification based on 52 items from five oblique factors. The constituent scales were Passivity (12 items, alpha = .81). Mastery (15 items, alpha = .79), Work Related Inadequacy (11 items, alpha = .72), Extraversion (4 items, alpha = .70) and Social Dependence (10 items, alpha = .66), all statistics compiled from the cross-validation sample. Correlations with Locus of Control ranged from 0.52 for Mastery to -.34 for Work Related Inadequacy. Distribution statistics for Locus of Control matched a comparable American sample. CONCLUSIONS: The five-scale structure exhibits good cross-validation characteristics and supports revealing analyses of relationships within the substantive study. Its 52-item format is suitable for research or exploratory use within its intended FE context.

Achievement↗
PubMed1999

The relationship between personality and attainment in 16-19-year-old students in a sixth form college: II: Self-perception, gender and attainment.

BACKGROUND: A related paper (Summerfield & Youngman, 1999) has described the development of a scale, the Student Self-Perception Scale (SSPS) designed to explore the relationship between academic self-concept, attainment and personality in sixth form college students. AIMS: The study aimed to identify groups of students exhibiting varying patterns of relationship using a range of measures including the SSPS. Issues of gender and also examined. SAMPLES: The samples comprised a pilot sample of 152 students (aged 16-17 years from two sixth form colleges) and a main sample of 364 students (mean age, 16 yrs 10 mths range 16:0 to 18:6 years, from one sixth form college). The main sample included similar numbers of male and female students (46% male, 54% female) and ethnic minority students comprised 14% of this sample. METHOD: Data comprised responses to two personality measures (the SSPS, Summerfield, 1995, and the Nowicki-Strickland Locus of Control Scale, Nowicki & Strickland, 1973), various student and tutor estimates of success, and performance data from college records. Students were classified using relocation cluster analysis and cluster differences verified using discriminant function analysis. Thirty outcome models were tested using covariance regression analysis. RESULTS: Eight distinct and interpretable groups, consistent with other research, were identified but the hypothesis of a positive, linear relationship between mastery and academic attainment was not sustained without qualification. Previous attainment was the major determinant of final performance. Gender variations were detected on the personality measures, particularly Confidence of outcomes, Prediction discrepancy, Passivity, Mastery, Dependency and Locus of control, and these were implicated in the cluster characteristics. CONCLUSIONS: The results suggest that a non-linear methodology may be required to isolate relationships between self-concept, personality and attainment, especially where gender effects may exist.

Achievement↗
PubMed1997

Mesial temporal spikes interfere with working memory.

The hippocampus and other mesial temporal structures support long-term memory and also are common foci for epilepsy. Recently it was shown that these brain structures may subserve the short-term storage and rehearsal processes called working memory in humans. We determined the accuracy of verbal and visuospatial working memory in the presence and in the absence of mesial temporal spikes in eight patients who had bilateral depth electrodes implanted to evaluate intractable epilepsy. Six of eight patients had declines in working memory performance during mesial temporal spiking, with the greatest disruption in spatial and verbal recall coincident with left hippocampal spikes (p = 0.019). Overall accuracy of working memory for all patients declined an average of 6% on spike trials. The two patients who did not have decreased accuracy during spike trials also had the best overall working memory performance. Mesial temporal spikes were not detected on extracranial recordings and yet may be associated with declines in working memory in some patients with epilepsy.

Action Potentials↗
PubMed1996

Antiepileptic medication and oral contraceptive interactions: a national survey of neurologists and obstetricians.

Hepatic enzyme-inducing antiepileptic drugs (AEDs) lower oral contraceptive (OC) sex hormone levels approximately 40% and increase the risk of unplanned pregnancies in women with epilepsy. AEDs also increase the risk of birth defects in offspring of women with epilepsy. We performed a national survey to determine obstetricians' and neurologists' knowledge of OC and AED interactions and the risk of birth defects for women with epilepsy taking AEDs. We received responses to a mailed questionnaire from 160 of 1,000 neurologists (16%) and 147 of 1,000 obstetricians (15%) from 47 states. Practice demographics and ages of responders were typical for U.S. neurologists and obstetricians. Ninety-one percent of neurologists and 75% of obstetricians said they treat women with epilepsy of child-bearing age. Only 4% of the neurologists and none of the obstetricians, however, knew the effects of the six most common AEDs on OCs, even though 27% of neurologists and 21% of obstetricians reported OC failures in their patients taking AEDs. Although increasing OC doses can compensate for insufficient OC sex hormone levels due to AEDs, most physicians do not increase the doses. Even though the risk of birth defects for the offspring of women with epilepsy is 4 to 6%, up from the background level of 2%, 44% of neurologists thought the risk was lower (0 to 3%), and some of the respondents guessed that it was as high as 50%. Many neurologists and obstetricians do not have accurate information to counsel women with epilepsy properly about their contraceptive and pregnancy choices.

Abnormalities, Drug-Induced↗
PubMed1990

Evaluation of N-acetylcysteine and methylprednisolone as therapies for oxygen and acrolein-induced lung damage.

Reactive oxidizing species are implicated in the etiology of a range of inhalational pulmonary injuries. Consequently, various free radical scavengers have been tested as potential prophylactic agents. The sulfydryl compound, N-acetylcysteine (NAC) is the only such compound clinically available for use in realistic dosages, and it is well established as an effective antidote for the hepatic and renal toxicity of paracetamol. Another approach in pulmonary injury prophylaxis is methylprednisolone therapy. We evaluated NAC and methylprednisolone in two rat models of inhalational injury: 40-hr exposure to greater than 97% oxygen at 1.1 bar and 15-min exposure to acrolein vapor (210 ppm). For oxygen toxicity, NAC (80 mg) or methylprednisolone (10 mg) were given IP every 2 or 6 hr, respectively. For acrolein, single doses of NAC (1 g/kg) and methylprednisolone (30 mg/kg) were given intravenously 15 min before exposure. In sham-exposed control animals, neither treatment favorably effected mortality, lung wet/dry weight ratios, or pulmonary histology. The increases in lung wet/dry weight ratios, seen with both oxygen and acrolein toxicity were reduced with both treatments. However, with oxygen, NAC therapy was associated with considerably increased mortality and histological changes. Furthermore, IP NAC administration resulted in large volumes of ascitic fluid. With acrolein, IV, NAC had no significant effect on mortality or pulmonary histological damage. Methylprednisolone had no beneficial effects on either the mortality or histological damage observed in either toxicity model. We caution against the ad hoc use of NAC in the management of inhalational pulmonary injury.

Acrolein↗
PubMed1986

An effect of CO2 on the maximum safe direct decompression to 1 bar from oxygen-nitrogen saturation.

An investigation into the maximum safe decompression step from oxygen nitrogen saturation to 1 bar was carried out with and without the presence of 0.02 bar carbon dioxide. The series, Islander 1, involved 13 teams of 5, fully informed, male volunteers carrying out simulated dives. One group of 6 teams carried out dives in an atmosphere of 0.4 bar oxygen, balance nitrogen (O2-N2); another group of 7 teams used an atmosphere of 0.38 bar oxygen, 0.02 bar carbon dioxide, balance nitrogen (O2-N2-CO2). The dives consisted of a 48-h stay at 1.7 or 1.8 bar to saturate the tissues, followed by decompression to 1 bar air at 0.5 bar/min. Two decompression parameters were studied; the incidence of decompression sickness (DCS) in the 24 h postdecompression, and the incidence and grade of venous gas emboli (VGE) in the first 6 h postdecompression. The grade of VGE was assessed using the Kisman-Masurel scoring system which produces a bubble grade with the subject at rest and after movement. No significant difference was found in the incidence of DCS between the two groups. Twenty subjects were decompressed from 1.7 bar using each mixture, without signs or symptoms of DCS. However, after decompression from 1.8 bar there were 2 cases of DCS in 10 subjects in the O2-N2 group and 2 cases in 15 subjects in the O2-N2-CO2 group. The incidence of detectable VGE was always lower in the O2-N2-CO2 group at both saturation pressures; at 1.7 bar the VGE incidence was lower by 40% (P less than 0.05) at rest and by 55% (P less than 0.001) after movement. At 1.8 bar the reduction was 3% (NS) at rest and 30% (NS) after movement. The results indicate that decompression from 1.8 bar to 1 bar, with or without the presence of 0.02 bar carbon dioxide, is likely to produce more than 5% DCS.

Adult↗
PubMed1980

Stability of carmustine in the presence of sodium bicarbonate.

The stability of carmustine in 5% dextrose injection and 0.9% sodium chloride injection, with and without added sodium bicarbonate, was studied at room temperature. Solutions of carmustine (0.1 mg/ml) in dextrose or saline with and without added sodium bicarbonate (1 meq/ml) were prepared. After 0, 15, 30, 60, and 90 minutes, aliquots of each test solution were analyzed for carmustine using the Bratton-Marshall test with absorbance at 540 nm. There was no significant decomposition of carmustine in dextrose or saline alone. However, the addition of sodium bicarbonate increased carmustine degradation; after 90 minutes, approximately 73% of the active drug remained. It is recommended that carmustine be neither admixed with nor administered piggyback with parenteral infusion solutions containing sodium bicarbonate.

Bicarbonates↗
PubMed1979

Spectrophotometric method applicable to in vitro studies of Heinz body formation in erythrocytes.

A simple quantitative procedure is described for the estimation of Heinz body formation in erythrocytes, based on the spectrophotometric measurement of the amount of crystal violet absorbed by precipitated Heinz bodies. Good correlation is shown between this method and the counting of Heinz body-containing erythrocytes in a microscopical preparation. This technique is particularly applicable to in vitro studies of the comparative effects produced in the erythrocyte by oxidant agents.

Erythrocyte Count↗
PubMed1978

Studies with primaquine in vitro: superoxide radical formation and oxidation of haemoglobin.

1. The production of superoxide radicals from primaquine diphosphate in aqueous solution has been demonstrated, using as indicator the reduction of cytochrome C with inhibition of the reaction by superoxide dismutase. 2. Primaquine-mediated oxidation of haemoglobin to methaemoglobin was reduced by the addition of catalase and increased by superoxide dismutase. Mannitol, a hydroxyl radical scavenger, abolished the increase in methaemoglobin observed in the presence of superoxide dismutase. EDTA reduced the oxidation of haemoglobin with and without superoxide dismutase. 3. Although the oxidation of haemoglobin in the presence of primaquine includes the effects of hydrogen peroxide, superoxide and hydroxyl radicals and metal ions, the results indicate that hydrogen peroxide, rather than the superoxide radical, is the main oxidizing species. The increase in haemoglobin oxidation occurring with superoxide dismutase may result from the augmented rate of hydrogen peroxide formation from superoxide radicals.

Catalase↗
PubMed1977

The effect of varying sea salt concentration in the growth medium on the chemical composition of a purified membrane fraction from Planococcus citreus Migula.

Membrane preparations were prepared from cells of Planococcus citreus grown in the presence of three final concentrations of sea salt in a basic growth medium. The concentration of salt in the medium affects the amount of membrane in the cell. The three preparations were subjected to chemical analysis and no significant changes in chemical composition were seen as the salt concentration in the medium was increased. Values for the various components generally were within normal ranges and were similar to those of non-halophiles rather than extreme halophiles. The protein levels were slightly higher and it it cellular ion balance. Atomic absorption analysis of the major cations associated with the membranes showed that divalent ions were present in a 2:1 ratio with ...

Calcium↗