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Biomedical subjects

E Richardson

Publications and source records attributed to E Richardson.

At least 19 recordsLinked to original sources
PubMed1995

Evaluation of a tuberculosis screening program for high-risk students in Toronto schools.

OBJECTIVE: To evaluate the effectiveness of a tuberculosis (TB) screening program for high-risk students in elementary and secondary schools. DESIGN: Cross-sectional study of the 1992-93 school screening program conducted by the Department of Public Health of the City of Toronto. Program costs were calculated with the use of 1993 wages, and costs for medical care were based on the 1993 fee schedule of the Ontario Medical Association. SETTING: Elementary and secondary schools in the City of Toronto. PARTICIPANTS: Students enrolled for the first time in any grade who were born in a country where TB is endemic or who were aboriginal Canadians were eligible. Of 44,179 students in Toronto schools 1775 met the eligibility criteria. INTERVENTION: Students were administered a Mantoux skin test, and those with a significant reaction (an induration of 10 mm or more in diameter) were advised to consult a physician for follow-up. OUTCOME MEASURES: Participation rate, number of participants with a significant reaction, percentage of these who were prescribed isoniazid and who completed chemoprophylaxis, potential number of preventable cases and costs associated with preventing each case. RESULTS: Of 1775 eligible students 42.9% (761) agreed to participate, and 40.6% (720) were screened. Significant skin-test reactions were detected in 22.5% (162/720) of the participants screened. Of these, 87.7% (142/162) saw a physician; subsequently, 2 cases of TB (1 active and 1 inactive) were detected. Of the remaining 140 students 44.3% (62) were prescribed isoniazid, of whom 9.7% (6/62) refused chemoprophylaxis. Of the remaining 56 students 82.1% (46) completed at least 6 months of chemoprophylaxis and 10.7% (6) were completing treatment at the end of the study. An estimated 3.2 cases were prevented, at a cost of $13,493.15 per case, whereas the undiscounted cost of treatment for an uncomplicated active case of TB in a patient under 19 years of age was $4503.82. CONCLUSIONS: The effectiveness of this screening program was significantly reduced by poor participation and poor rates of prescription of isoniazid by physicians. Appropriate strategies are needed to reduce barriers to the implementation of these programs.

Adolescent↗
PubMed1995

UV-light induces delayed mutations in Chinese hamster cells.

The possibility was examined that mutational events at the glucose 6-phosphate dehydrogenase locus can be delayed for significantly more than one or two cell divisions following treatment of Chinese hamster cells with UV light. To detect these later mutant events, the proportion of G6PD-mutant cells in a colony was obtained by replating cells from a single colony 5-7 days after UV irradiation and staining the resulting colonies for G6PD activity. Eight colonies out of a total of 1657 colonies from the treated population yielded G6PD-negative colonies upon replating, while no mutant clones were obtained from 947 colonies grown from untreated cells. One clone contained only mutant cells suggesting that the mutation occurred before the first cell division after irradiation. A second clone contained a 1:1 ratio of mutant to wild-type cells suggesting that the mutation occurred at the first cell division. The remaining six clones contained low numbers of mutant cells and the ratio of mutant to wild-type cells in these clones was in agreement with the theoretical ratios expected for mutations occurring at the fourth (1:13), sixth (1:63), seventh (1:127), eighth (1:255), ninth (1:511), and eleventh (1:2047) cell division after UV light exposure. G6PD-mutant cells deficient in staining activity were isolated from five clones and all have significant reductions in G6PD activity confirming the genetically stable character of these mutants. These results support the conclusion that UV light induces mutants for up to 11 cell generations after treatment of mammalian cells and suggest that mutagens can induce in mammalian DNA long-term alterations which act to increase the apparently spontaneous mutation frequency.

Animals↗
PubMed1994

Depression, suicidal ideation, and substance use among adolescents. Are athletes at less risk?

OBJECTIVES: To determine the relationship between participation in high school athletic programs and depression, suicidal ideation, and substance use, and to study the high-risk behaviors of suicidal ideation and substance use. DESIGN: Survey. SETTING: A suburban public high school in Kentucky. PARTICIPANTS: We received 823 (80%) responses from 1030 potential respondents. Athletes (ie, participation on a high school athletic team) were compared with non-athletes. MEASURES: Depression was measured by the Children's Depression Inventory by an index of suicidal ideation by an indicator of a past suicide attempt, and by current use of tobacco, alcohol, marijuana, and cocaine. RESULTS: Thirty percent of the sample participate in school athletic teams. Athletes are less depressed, have less suicidal ideation and attempts, and are less likely to currently smoke cigarettes or marijuana. The use of smokeless tobacco and cocaine was not related to athletic participation. After controlling for demographic characteristics, no difference in alcohol use was found between athletes and nonathletes. CONCLUSIONS: Athletic participation is a marker for a decreased likelihood of depression and some high-risk behaviors in adolescents. Future research could help in creating alternative interventions beyond participation in varsity and junior varsity athletic teams.

Adolescent↗
PubMed1994

Large corneal transplants in corneal destructive disease.

PATIENTS AND METHODS: Forty nine keratoplasties were performed in 18 eyes of 17 patients with severe corneal destructive disease. RESULTS: One eye became phthisical and 5 others lost useful visual acuity but retained a satisfactory cosmetic result. No eyes were enucleated. Recurrence of the host disease in the graft was the largest cause of visual failure. Primary allograft rejection was rare in spite of the large size of the grafts and their proximity to the limbus and new vessels. CONCLUSION: For these grafts to succeed it is essential to bring the underlying systemic disease under control by intensive systemic immunosuppressive therapy before, during and for many months after surgery. It was found that those with Mooren's ulcer had the worst prognosis for the retention of vision.

Corneal Diseases↗
PubMed1994

Predicting the disability of first-time stroke sufferers at 1 year. 12-month follow-up of a population-based cohort in southeast England.

BACKGROUND AND PURPOSE: The purpose of this study was to predict the functional outcome at 1 year of first-time stroke patients aged younger than 75 years in relation to the severity of stroke and demographic characteristics. METHODS: Population registers in three districts of southeast England were established in August 1989, with notification by stroke registry field-workers, general practitioners, and rehabilitation practitioners. Assessments were made using the Barthel index for activities of daily living at the time of maximum impairment and at 3 and 12 months after the stroke. RESULTS: Of 639 registered stroke patients, 392 without previous disability survived and were assessed for disability at 3 months, of whom 34 (9%) were severely disabled and 60 (15%) moderately disabled. Initial incontinence was the best single predictor of disability with a sensitivity of 60% and a specificity of 78%. Two hundred twenty-five patients (35%) were eligible for 12-month follow-up; 11% had moderate or severe disability, for which initial incontinence was the best predictor. CONCLUSIONS: There is no evidence from this study of an association between demographic characteristics and the disability status of stroke survivors in the medium term. Multivariable predictors of disability had little advantage over incontinence within 24 hours of the stroke. The estimates of the prevalence of disability from this large population-based study are relevant when assessing the medium-term needs of stroke patients.

Activities of Daily Living↗
PubMed1993

Does the incidence, severity, or case fatality of stroke vary in southern England?

STUDY OBJECTIVES: To determine differences in incidence and case fatality of stroke in district health authorities with differing standardised mortality ratios (SMR) for stroke in residents aged under 65 years in whom death from stroke is considered 'avoidable'. DESIGN: Registration of first ever strokes in three district health authorities. Patients were assessed and followed up over one year by one of three observers. SETTING: West Lambeth, Lewisham and North Southwark, and Tunbridge Wells District Health Authorities in south east England. PARTICIPANTS: Patients under the age of 75 years having a first ever in a lifetime stroke between 15 August 1989 and 14 August 1990. MEASUREMENTS AND MAIN RESULTS: Age specific incidence rates and survival time from stroke to death. Severity was assessed in terms of the level of consciousness and the presence of speech, urinary, and motor impairment within the first 24 hours of the stroke. Altogether 386 strokes were registered. There was a significant difference in the incidence rate between district health authorities in those aged under 65 (p < 0.01). The overall case fatality was 26% at three weeks with no significant difference between the districts. Poor survival was associated jointly with increased age and with coma, incontinence, and swallowing impairment in the first 24 hours after a stroke. CONCLUSIONS: The SMRs for stroke in those aged under 65 in these three health districts reflect the incidence of stroke. Case fatality at three weeks does not vary between these districts and consequently would not be a sensitive indicator of the quality of care. This also suggests that differences in services between the districts did not lead to changes in prognosis. In districts with high SMRs for stroke there is a need for further study and reduction of risk factors, thereby reducing the incidence and burden of stroke locally. This study provides a framework for assessing the needs for stroke prevention and treatment in both rural and urban areas without an elaborate protocol and detailed neurological assessment.

Adult↗
PubMed1993

Patterns of acute stroke care in three districts of southern England.

OBJECTIVE: To quantify the use of health care services by acutely ill stroke patients in three district health authorities. DESIGN: A follow up study of all patients recorded in population based registers who had a first ever stroke in three district health authorities, with assessment following the onset and three months after the stroke. SETTING: West Lambeth, Lewisham and North Southwark, and Tunbridge Wells District Health Authorities in south east England. SUBJECTS: All first time stroke patients under the age of 75 years who presented between 15 August 1989 and 14 August 1990. MEASUREMENTS AND MAIN RESULTS: Hospital admission rates, rates of use of rehabilitation services, and contact with medical practitioners together with assessment of disability and handicap were determined. A total of 386 strokes were registered. Seventy eight per cent were treated in hospital and younger and incontinent patients were significantly more likely to be admitted. The median stay was 21 days. Patients in West Lambeth, those paralysed, and those who stayed longer in hospital were more likely to receive physiotherapy. Altogether 265 patients were followed up, 117 having died within three months of the stroke. During the three months, 150 (57%) had seen a hospital physician and 181 (69%) their general practitioner, but 18 (7%) had seen neither. Sixty seven (26%) patients were moderately or severely disabled. Twenty seven per cent of inpatients had received no inpatient physiotherapy and 67% of all patients no outpatient physiotherapy during the three months. CONCLUSIONS: The hospital admission rates were high, with long lengths of stay. There were significant differences in the amount of rehabilitation received in each district. This was low overall, especially for those not admitted to hospital. As expected, patients admitted for long periods were the most likely to receive therapy. Before district policies for admission and management of stroke patients can be drawn up, increased knowledge of which aspects of stroke management are effective is needed. Policies should aim to provide planned, coordinated care between hospital and the community. It is striking that many patients received no form of rehabilitation therapy.

Acute Disease↗
PubMed1991

Renin production after experimental extracorporeal shock wave lithotripsy: a primate model.

Since the advent of extracorporeal shock wave lithotripsy (ESWL) concern has surfaced as to the long-term risk of the development of hypertension, as well as risk to the developing kidney. To study this concern 8 infant and 3 adult rhesus monkeys (Macaca mulatta) underwent treatment with the XL1 experimental lithotriptor to 1 kidney varying the amount of voltage and shocks. Followup consisted of measurement of renin levels and quantitative renal scans, using 131iodine hippurate to calculate effective renal plasma flow. In the infants a slight change was noted in the absolute effective renal plasma flow of the treated kidney versus the untreated side but it was not statistically different. When indexed to body surface area in the growing animal, there was a statistically significant decrease in renal function. However, peripheral renin levels were markedly elevated in the infants at 3 weeks, and they gradually declined during the 6-month period, although levels remained elevated over baseline. The adults also had central renin levels drawn from the renal vein on the treated side, and there was a close correlation with the peripheral levels, which peaked at 3 weeks and returned to normal. Thus, it seems that at least in the short term renin production is increased in infants more than adults. This finding may be an indicator as to renal damage and is a possible explanation for hypertension occurring after ESWL.

Animals↗
PubMed1990

Isolation of Chinese hamster ovary cells with reduced poly(ADP-ribose) polymerase activity.

The biological function of poly(ADP-ribose) polymerase in DNA repair, cell-cycle regulation and cellular differentiation has yet to be defined. Isolation of cells which are deficient in poly(ADP-ribose) synthesis would greatly facilitate the determination of the biological role of this enzyme. A method is described for isolating Chinese hamster ovary (CHO) cells deficient in the poly(ADP-ribose) polymerase activity by direct screening of colonies for enzyme activity. Colonies with decreased production of poly(ADP-ribose) are recovered from nylon replicas for further analysis. Using this method we have isolated a series of CHO cells which have 50% or less poly(ADP-ribose) polymerase activity. These mutants have normal generation times and are 20% more sensitive to the effects of DNA (m)ethylating agents than the parental cell. However, these mutants display normal sensitivity to gamma-rays.

Animals↗
PubMed1989

Effects of experimental and habitual lunch-size on performance, arousal, hunger and mood.

Twelve male students who normally ate a large lunch and 12 who normally ate only a light lunch performed a sustained attention task before and after eating a light lunch and before and after eating a heavy lunch. The speed and accuracy of performance were measured; so also were temperature, pulse rate and subjective estimates of tension, alertness and hunger. The changes brought about by the meals were examined. Speed alone showed no change over the lunch interval. Of the remaining seven measures, only temperature, which seems to reflect endogenous processes, was unaffected by the size of the lunch that was eaten. Accuracy, pulse rate and hunger were influenced by the size of the habitual lunch as well as by the size of the experimental lunch. Tension and alertness were responsive only to the size of the experimental lunch. The results are discussed in relation to diurnal rhythms, with a particular emphasis on the acquisition of endogenous component processes, as exemplified by habits of eating.

Adult↗
PubMed1989

Genetic analysis of XR-1 mutation in hamster and human hybrids.

We investigated the dominant/recessive nature of the XR-1 mutant locus in intraspecies Chinese hamster ovary (CHO) hybrids and interspecies hybrids with human cell lines that possess different radioresistances. The XR-1 cell is abnormally sensitive to killing by gamma rays in the G1 phase of the cell cycle, while late-S-phase cells have wild-type resistance. [3H]Thymidine selection was used to eliminate the resistant S-phase population. In both intraspecies and interspecies hybrids, the XR-1 mutation is recessive to the wild-type cell and is not influenced by differences in chromosome ploidy. Analysis of hybrids between human ataxia telangiectasia fibroblasts AT5BI and XR-1 cells revealed that they possess different genetic defects as they complemented each other in three of four hybrids tested. These data suggest that the XR-1 locus is evolutionarily conserved between hamster and human cells.

Animals↗
PubMed1989

Isolation and characterization of glucose-6-phosphate dehydrogenase-deficient Chinese hamster cells derived from pure mutant colonies.

Ten pure glucose-6-phosphate dehydrogenase (G6PD)-deficient mutants were isolated from colonies composed entirely of cells which lacked G6PD staining activity. These mutants were analyzed for G6PD enzyme activity and the presence of immunologically cross-reactive proteins using immunoblotting techniques and antiserum directed against bovine G6PD. Four mutants had no detectable enzyme activity and did not contain protein which produces a detectable cross-reaction with G6PD antibody. One mutant had residual enzyme activity and altered electrophoretic mobility but did not have detectable immunological cross-reactivity. These results could be explained by either a DNA deletion or point mutational mechanism. On the other hand, five of the 10 mutants analyzed had characteristics consistent with a point mutation in the G6PD gene. All contain a protein which cross-reacts with the G6PD antibody and have the same subunit molecular weight as the parent cell's G6PD enzyme. Four of the five mutants had residual G6PD enzyme activity. Thus, the mechanism for the formation of pure mutants is not simply DNA deletion but is probably a more complex process involving the transfer of altered genetic information from one DNA strand to the other.

Animals↗
PubMed1988

Neuropsychiatric, psychoeducational, and family characteristics of 14 juveniles condemned to death in the United States.

Of the 37 juveniles currently condemned to death in the United States, all of the 14 incarcerated in four states received comprehensive psychiatric, neurological, neuropsychological, and educational evaluations. Nine had major neurological impairment, seven suffered psychotic disorders antedating incarceration, seven evidenced significant organic dysfunction on neuropsychological testing, and only two had full-scale IQ scores above 90. Twelve had been brutally physically abused, and five had been sodomized by relatives. For a variety of reasons the subjects' vulnerabilities were not recognized at the time of trial or sentencing, when they could have been used for purposes of mitigation.

Adolescent↗