Search PubMed⌕ Search

Biomedical subjects

M Stevens

Publications and source records attributed to M Stevens.

At least 37 records · Page 2Linked to original sources
PubMed1999

Positive and negative outcome expectations of smoking: implications for prevention.

BACKGROUND: To inform the development of messages for tobacco prevention programs, we examined seven positive and five negative outcome expectations of smoking as risk factors for smoking uptake. METHODS: A cross-sectional, self-administered survey of 471 students in grades 6-12 who were never or experimental smokers was performed. Logistic regression was used to examine the relationship between outcome expectations and susceptibility to becoming a smoker in the future, a measure of intent and resistance to peer smoking. RESULTS: A total of 36.1% of the sample was susceptible to smoking. All positive outcome expectations showed a strong and significant association with susceptibility. Students were most likely to be susceptible if they believed they would enjoy smoking (OR = 29.4). Three of the five negative outcome expectations were significantly associated with susceptibility, but the strength of these associations was much lower than that observed for the positive expectations (OR = 0.5 to 0.6). A strong belief in the negative outcomes of smoking did not alter the association between susceptibility and positive outcome expectations. CONCLUSIONS: These findings suggest that teaching adolescents and teens about the negative consequences of smoking is unlikely to change their intent to smoke. Preventive efforts should identify ways to address the positive expectations adolescents have about smoking, possibly by offering alternative means for achieving these outcomes.

Adolescent↗
PubMed1999

CYP 3A proteins are expressed in human neutrophils and lymphocytes but are not induced by rifampicin.

Cytochrome P-450 3A (CYP 3A) enzymes, the prominent subfamily in the cytochrome system, are expressed in various extrahepatic tissues. Until now, their expression has been demonstrated in human polymorphic neutrophils (PMNs) but not in lymphocytes using immunohistochemistry and immunoblot analysis. Moreover, their potential modulation has not been determined yet. To study such an expression in different peripheral blood cell populations, rifampicin (600 mg/day during 6 days) was given to 8 healthy subjects. PMNs and lymphocytes were isolated by centrifugation of whole white blood cell fractions using Ficoll gradients before drug administration, immediately after, and 3 days after drug withdrawal. PMN and lymphocyte smears and homogenates were subjected to immunostaining and immunoblotting, respectively, with a mouse monoclonal antibody recognizing all CYP 3A proteins. These proteins were quantified by densitometric analysis. Before and after rifampicin administration, a positive cytoplasmic staining was observed in all PMNs and in about 50% of lymphocytes. CYP 3A expression in lymphocytes was further confirmed by positive immunoblots for lymphocyte homogenates. Neither in PMNs nor in lymphocytes, induction of CYP 3A protein expression was observed after rifampicin treatment despite overall induction of CYP 3A activity assessed by the urinary excretion of 6beta-hydroxycortisol. These results demonstrate that CYP 3A proteins are constitutively expressed not only in PMNs but also in lymphocytes. However, in both cell lineages CYP 3A protein expression was not induced by rifampicin.

Adult↗
PubMed1999

The relationship between alcohol consumption patterns and injury.

AIMS AND DESIGN: A case-control design was employed to quantify the risk of injury after the recent consumption of alcohol. PARTICIPANTS AND SETTING: A total of 797 cases and 797 controls were interviewed throughout 1997. A response rate of 82% was calculated for eligible cases who were approached by an interviewer. The rate for interviews conducted of all people presenting with an injury during the study period was 67%. Cases were injured patients from a hospital emergency unit. Controls were matched on suburb and were interviewed at home regarding activities leading up to the time of their matched case's injury. MEASUREMENTS: Cases and controls were questioned about the injury event and alcohol and other drug use consumed in the 6 hours prior to the injury. They were also breath-tested and medical records were checked for validation purposes. FINDINGS: Logistic regression analysis produced an odds ratio of 3.4 (95% CI: 1.8-6.4) for the risk of sustaining an injury after consuming more than 60 g of alcohol in a 6-hour period, after controlling for demographic variables. The risk of injury at different levels of alcohol use was substantially higher for females with a significant odds ration of 9.6 at greater than 60 g of alcohol compared to 2.1 for men. CONCLUSIONS: These results need to be interpreted cautiously, but provide additional support that the risk of injury increases with the quantity of alcohol consumed and that the risk of injury is significantly higher for women.

Adolescent↗
PubMed1999

Epidemiology of Cryptosporidium parvum in symptomatic paediatric oncology patients.

BACKGROUND: Although Cryptosporidium parvum is known to cause significant morbidity in immunocompromised individuals, including adults with cancer, the epidemiology of this pathogen in paediatric oncology patients is not known. OBJECTIVE: We prospectively investigated the incidence of symptomatic C. parvum infection in children receiving treatment for malignancy. METHODOLOGY: Over a 9 month period, all oncology inpatients with diarrhoea had stool analysis for C. parvum oocysts. The incidence of cryptosporidiosis was also recorded in non-oncology patients who had a stool analysed for C. parvum during the 6 years of the study period. RESULTS: None of the 149 stool samples from 60 oncology patients analysed contained C. parvum oocysts. Thirteen per cent of 173 samples from non-oncology patients were positive for C. parvum oocysts. CONCLUSIONS: In contrast to studies of adult oncology patients, paediatric oncology patients in our institution appear at low risk of cryptosporidiosis.

Animals↗
PubMed1999

High prevalence of mutations in the microtubule-associated protein tau in a population study of frontotemporal dementia in the Netherlands.

Mutations in microtubule-associated protein tau recently have been identified in familial cases of frontotemporal dementia (FTD). We report the frequency of tau mutations in a large population-based study of FTD carried out in the Netherlands from January 1994 to June 1998. Thirty-seven patients had >/=1 first-degree relative with dementia. A mutation in the tau gene was found in 17.8% of the group of patients with FTD and in 43% of patients with FTD who also had a positive family history of FTD. Three distinct missense mutations (G272V, P301L, R406W) accounted for 15.6% of the mutations. These three missense mutations, and a single amino acid deletion (DeltaK280) that was detected in one patient, strongly reduce the ability of tau to promote microtubule assembly. We also found an intronic mutation at position +33 after exon 9, which is likely to affect the alternative splicing of tau. Tau mutations are responsible for a large proportion of familial FTD cases; however, there are also families with FTD in which no mutations in tau have been found, which indicates locus and/or allelic heterogeneity. The different tau mutations may result in disturbances in the interactions of the protein tau with microtubules, resulting in hyperphosphorylation of tau protein, assembly into filaments, and subsequent cell death.

Dementia↗
PubMed1999

Nine-year follow-up of successful placement of endosseous implants in a mandibular bone graft.

Facial trauma injuries secondary to gunshot wounds present a unique challenge. These wounds are avulsive and typically involve the destruction of soft tissue with bone loss. A technique in bone transplantation is that of particulate cancellous bone and marrow. Initial form and stability can be provided by a titanium mesh tray or reconstruction plates while the graft undergoes maturation and consolidation. Dental implants can then be placed in this grafted site to provide stabilization for a functional and comfortable prosthesis and for the support of the peri-oral soft tissues.

Bone Transplantation↗
PubMed1999

Protein 4.1R-deficient mice are viable but have erythroid membrane skeleton abnormalities.

A diverse family of protein 4.1R isoforms is encoded by a complex gene on human chromosome 1. Although the prototypical 80-kDa 4.1R in mature erythrocytes is a key component of the erythroid membrane skeleton that regulates erythrocyte morphology and mechanical stability, little is known about 4.1R function in nucleated cells. Using gene knockout technology, we have generated mice with complete deficiency of all 4.1R protein isoforms. These 4.1R-null mice were viable, with moderate hemolytic anemia but no gross abnormalities. Erythrocytes from these mice exhibited abnormal morphology, lowered membrane stability, and reduced expression of other skeletal proteins including spectrin and ankyrin, suggesting that loss of 4. 1R compromises membrane skeleton assembly in erythroid progenitors. Platelet morphology and function were essentially normal, indicating that 4.1R deficiency may have less impact on other hematopoietic lineages. Nonerythroid 4.1R expression patterns, viewed using histochemical staining for lacZ reporter activity incorporated into the targeted gene, revealed focal expression in specific neurons in the brain and in select cells of other major organs, challenging the view that 4.1R expression is widespread among nonerythroid cells. The 4.1R knockout mice represent a valuable animal model for exploring 4.1R function in nonerythroid cells and for determining pathophysiological sequelae to 4.1R deficiency.

Animals↗
PubMed1999

High-dose melphalan with autologous stem-cell rescue in metastatic rhabdomyosarcoma.

PURPOSE: The European Collaborative MMT4-91 trial was conducted as a prospective nonrandomized study to evaluate the potential benefit of high-dose melphalan as consolidation of first complete remission in children with stage IV rhabdomyosarcoma. PATIENTS AND METHODS: Fifty-two patients in complete remission after six courses of chemotherapy received "megatherapy": 42 received melphalan alone, whereas 10 received melphalan in combination with etoposide, carboplatin/etoposide, or thiotepa/busulfan and etoposide. The outcome of this group of patients was compared with that observed in 44 patients who were also in complete remission after six courses of identical chemotherapy (plus surgery or radiotherapy) but went on to receive a total of up to 12 courses of conventional chemotherapy (four cycles). No differences were found between the two groups regarding clinical characteristics, chemotherapy received before complete remission, or response to chemotherapy. In particular, there was no significant difference between the groups for site of primary tumor, histologic subtype, age at presentation, presence of bone or bone marrow metastases, or number of metastases. RESULTS: The 3-year event-free survival (EFS) and overall survival (OS) rates were 29.7% and 40%, respectively, for those receiving high-dose melphalan or other multiagent high-dose regimens and 19.2% and 27.7%, respectively, for those receiving standard chemotherapy. The difference was not statistically significant (P =.3 and P =.2 for EFS and OS, respectively). There was a significant prolongation in the time from the last day of high-dose chemotherapy or the end of chemotherapy cycle 4 to the time of relapse in those receiving megatherapy (168 days for patients receiving megatherapy v 104 days for those receiving standard therapy; P =.05). CONCLUSION: The addition of a high-dose alkylating agent to consolidation therapy may have prolonged progression-free survival in this poor-risk patient group, but it did not significantly improve the ultimate outcome.

Adolescent↗
PubMed1999

Outbreak of hepatitis A in Rotterdam associated with visits to 'darkrooms' in gay bars.

An unexpectedly large number of hepatitis A virus (HAV) infections were notified among homosexual men in Rotterdam in the first five months of 1998. A case control study was conducted to investigate the hypothesis that this outbreak was associated with sexual practices and to collect information with which to focus preventive activities. Notified cases and controls selected from male members of a gay sports club completed anonymous questionnaires about known risk factors for HAV infection and sexual behaviour. Single variable analysis showed that HAV infection was associated with sexual contact with anonymous sex partners (odds ratio (OR) 4.6; 95% confidence interval (CI) 1.0-23.2) and with visits to 'darkrooms' in gay bars (OR 6.2; 95% CI 1.5-26.8). A negative association with travel abroad to western countries was observed (OR 0.4; 95% CI 0.1-1.3). The associations with visits to darkrooms (OR = 9.2; 95% CI 1.6-52.4) and travel abroad to western countries (OR 0.1; 95% CI 0.02-0.9) remained significant in a multivariable logistic regression analysis. This risk group was targeted for health education and vaccination and darkroom owners were advised to provide hygiene facilities.

Adult↗
PubMed1998

Association of missense and 5'-splice-site mutations in tau with the inherited dementia FTDP-17.

Thirteen families have been described with an autosomal dominantly inherited dementia named frontotemporal dementia and parkinsonism linked to chromosome 17 (FTDP-17), historically termed Pick's disease. Most FTDP-17 cases show neuronal and/or glial inclusions that stain positively with antibodies raised against the microtubule-associated protein Tau, although the Tau pathology varies considerably in both its quantity (or severity) and characteristics. Previous studies have mapped the FTDP-17 locus to a 2-centimorgan region on chromosome 17q21.11; the tau gene also lies within this region. We have now sequenced tau in FTDP-17 families and identified three missense mutations (G272V, P301L and R406W) and three mutations in the 5' splice site of exon 10. The splice-site mutations all destabilize a potential stem-loop structure which is probably involved in regulating the alternative splicing of exon10. This causes more frequent usage of the 5' splice site and an increased proportion of tau transcripts that include exon 10. The increase in exon 10+ messenger RNA will increase the proportion of Tau containing four microtubule-binding repeats, which is consistent with the neuropathology described in several families with FTDP-17.

Alternative Splicing↗
PubMed1998

Predictors of smoking cessation in adolescents.

OBJECTIVE: To examine factors associated with cessation of smoking in adolescents 12 to 18 years of age who smoke cigarettes. DESIGN AND SETTING: Prospective school-based cohort study of 1384 New Hampshire high school students surveyed at baseline and annually up to 3 subsequent years regarding their substance abuse behaviors, including adolescents who smoked 1 or more cigarettes within the past 30 days at baseline. OUTCOME MEASURES: Cessation behavior was defined by a subsequent response indicating nonsmoking status. We examined associations between smoking cessation and baseline measurements of the level of addiction (cigarette consumption pattern), experience with quitting, intent to quit now and in the future, opinion of adults smoking more than 1 pack of cigarettes per day, social influences to smoke, sex, and psychological attributes. RESULTS: Of 276 adolescents who qualified as cigarette smokers at baseline, 123 (44.6%) were occasional smokers, 65 (23.6%) were daily smokers of 1 to 9 cigarettes, and 88 (31.9%) were daily smokers of 10 or more cigarettes. While 39 (14.1%) had smoked for 1 year or less, 62 (22.5%) had smoked for 6 or more years. Seventy-five (27.2%) reported failed past attempts to quit smoking, 71 (25.7%) reported wanting to quit now, and 50 (18.1%) reported definitely intending to be a nonsmoker in the future. Seventy-nine smokers (28.6%) described themselves as nonsmokers in follow-up surveys. The smoking cessation rate was 46.3% among occasional smokers, 12.3% among daily smokers of 1 to 9 cigarettes, and 6.8% among daily smokers of 10 or more cigarettes. Smoking cessation was associated with occasional smoking status (adjusted odds ratio 6.67 compared with daily smokers of 10 or more cigarettes [95% confidence intervals, 2.26-19.69]), and definite intentions to quit in the future (2.67 [95% confidence intervals, 1.2-5.7]). Most of those with definite intentions to quit in the future were occasional smokers (92.0%). CONCLUSIONS: This study documents cessation of smoking in nearly one third of the adolescent smokers. The cessation rate among daily smokers of 10 or more cigarettes per day is comparable with adult cessation rates. Adolescents who are less addicted, measured by low frequency of cigarette use, are more likely than daily users to quit. In addition, definite intent to quit in the future predicts cessation, but only among occasional smokers. In contrast with adults, experience with quitting was not associated with a higher likelihood of cessation. Pediatricians should focus on keeping occasional smokers from moving into daily smoking status, where nicotine addiction begins to play a prominent role in maintaining the behavior. Further study is needed to guide enhancement of the recruitment of adolescents into cessation, assessment of nicotine dependence in daily adolescent smokers, and appropriate use of nicotine replacement therapy in this group.

Adolescent↗
PubMed1998

The prevalence of and risk factors for atopy in early childhood: a whole population birth cohort study.

OBJECTIVES: A birth cohort was followed-up to age 4 years to record the development of allergic disorders and to study the influence of genetic and environmental factors. METHODS: Information on family history and environmental factors was obtained at birth, and serum cord IgE was measured. At age 4 years, 1218 children were reviewed. RESULTS: By age 4 years, 27% of the children had symptoms of allergic disease. Period prevalence of asthma increased from 8.7% in infancy to 14.9% at 4 years. Family history of atopy was the single most important risk factor for atopy in children. Sibling atopy was a stronger predictor of clinical disease than maternal or paternal atopy, whereas paternal atopy, male sex, and high cord IgE were significant for the development of allergen sensitization. Children of asthmatic mothers were three times more likely to have asthma (odds ratio [OR]: 3.0, 95% confidence interval [CI]: 1.6-5.8) and rhinitis (OR: 2.9, CI: 1.1-7.4). Formula feeding before 3 months of age predisposed to asthma at age 4 years (OR: 1.8, CI: 1.2-2.6). The effect of maternal smoking on childhood wheeze seen at 1 and 2 years was lost by age 4, except for a subgroup with negative skin test responses (nonatopic asthma). Less than half (46%) of the infantile wheezers were still wheezing at 4 years of age. CONCLUSION: Family history of atopy remains the most important risk factor for atopy in children, but other markers can be identified with a potential for intervention at an early age.

Animals↗
PubMed1998

Role of written advance directives in decision making: insights from qualitative and quantitative data.

OBJECTIVE: To understand the role of written advance directives (ADs) in medical decision making through examination of qualitative and quantitative data sources. We specifically wanted to address whether physicians unilaterally disregard advance directives. DESIGN: Block randomized controlled trial to improve decision making and outcomes of seriously ill patients. SETTING: Five academic medical centers. PATIENTS: Fourteen hospitalized, seriously ill adults were randomized to receive an intervention of patient-specific information on prognoses and specially trained nurse to facilitate decision making. To be included in this analysis, patients reported having an AD and also met one of these criteria of severity: were comatose, had objective estimate of prognosis for surviving 2 months of 40% or less, or died during this hospital admission. MEASUREMENTS AND MAIN RESULTS: Quantitative data sources consisted of medical record review and interviews with the patient (when possible), surrogate, and responsible physician about prognosis, symptoms, preferences, and decision making. Qualitative data consisted of narratives by the nurse responsible for counseling and facilitating decision making. Each element of the quantitative database was reviewed, and a timeline of communication and decision making was constructed. Qualitative data were analyzed using grounded theory and narrative summary analysis. We compared and contrasted qualitative and quantitative data to better understand the role of ADs in decision making. In each case, the patient had a period of diminished capacity in which ADs should have been invoked. Advance directives played an important role in decision making of 5 of 14 cases, but even in those cases, life-sustaining treatment was stopped only when the patient was "absolutely, hopelessly ill." In two of these cases, the family member wrongly reported that the patient had an AD, and in the remaining seven cases, ADs had a limited role. The limited role could not be traced to a single explanation. Rather, a complex interaction of several factors was identified: patients were not considered hopelessly ill, so the directive was never seen as applicable and a transition in the goals of care did not occur; family members or the designated surrogate were not available, were ineffectual, or were overwhelmed; or the content of the AD was vague, or not applicable to the clinical situation, and the intent in completing the AD was never clarified. A physician did not unilaterally disregard a patient's preference in any of the cases. Two factors that enhanced the role of the AD were an available surrogate who was able to advocate for the patient and open communication between the physician and the surrogate in which the patient's prognosis was reconsidered. CONCLUSIONS: Our findings indicate that physicians are not unilaterally disregarding patients' ADs. Despite the patients' serious illnesses, family members and physicians did not see them as "absolutely, hopelessly ill." Hence, ADs were not considered applicable to the majority of these cases. Cases in which ADs had an impact evidenced open negotiation with a surrogate that yielded a transition in the goals of care.

Adult↗
PubMed1998

Experiences of mothers in five countries whose child died of cancer.

Although increasing attention is being focused on the emotional aspects of caring for dying children and their families, few research reports concentrate on the experiences of mothers, particularly in different countries. This article describes the findings of an exploratory, descriptive study that investigated the experiences of mothers from five different countries who each had a child die from cancer in the past 6 months. Principal investigators, members of the International Work Group on Death, Dying, and Bereavement, conducted semistructured interviews with 21 mothers in their own countries. No culturally related differences were noted among mothers, and the mothers' recall of their experiences are more similar than different. All mothers, irrespective of country, described similar reactions to the diagnosis, management of the end-stage illness, and challenge of coping with bereavement. Lessons learned from this project provide suggestions for future research across countries.

Adolescent↗
PubMed1998

Use of dialectical behavior therapy in a partial hospital program for women with borderline personality disorder.

Dialectical behavior therapy, an outpatient psychosocial treatment for chronically suicidal women with borderline personality disorder, has been adapted for use in a partial hospital program for women. Patients attend the program for a minimum of five days of individual and group therapy, and full census is 12 women. About 65 percent of participants meet at least three criteria for borderline personality disorder, and most have suicidal and self-injurious behavior. Their comorbid diagnoses include trauma-related diagnoses and anxiety disorders, severe eating disorders, substance abuse, and depression. The partial hospital program is linked to an aftercare program offering six months of outpatient skills training based on dialectical behavior therapy. Both programs focus on teaching patients four skills: mindfulness (attention to one's experience), interpersonal effectiveness, emotional regulation, and distress tolerance. Two years of operation of the women's partial hospital program provides promising anecdotal evidence that dialectical behavioral therapy, an outpatient approach, can be effectively modified for partial hospital settings and a more diverse population.

Adult↗