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Biomedical subjects

L Hanson

Publications and source records attributed to L Hanson.

At least 19 recordsLinked to original sources
PubMed1999

Genome structure and evolution in the allohexaploid weed Avena fatua L. (Poaceae).

Allohexaploid wild oat, Avena fatua L. (Poaceae; 2n = 6x = 42), is one of the world's worst weeds, yet unlike some of the other Avena hexaploids, its genomic structure has been relatively little researched. Consequently, in situ hybridisation was carried out on one accession of A. fatua using an 18S-25S ribosomal DNA (rDNA) sequence and genomic DNA from A. strigosa (AA-genome diploid) and A. clauda (CC-genome diploid) as probes. Comparing these results with those for other hexaploids studied previously: (i) confirmed that the genomic composition of A. fatua was similar to the other hexaploid Avena taxa (i.e., AACCDD), (ii) identified major sites of rDNA on three pairs of A/D-genome chromosomes, in common with other Avena hexaploids, and (iii) revealed eight chromosome pairs carrying intergenomic translocations between the A/D- and C-genomes in the accession studied. Based on karyotype structure, the identity of some of these recombinant chromosomes was proposed, and this showed that some of these could be divided into two types, (i) those common to all hexaploid Avena species analysed (3 translocations) and (ii) one translocation in this A. fatua accession not previously observed in reports on other hexaploid Avena species. If this translocation is found to be unique to A. fatua, then this information, combined with more traditional morphological data, will add support to the view that A. fatua is genetically distinct from other hexaploid Avena species and thus should retain its full specific status.

Avena↗
PubMed1997

Combined exposure to cigarette smoke and hypercholesterolemia decreases vasorelaxation of the aorta.

PURPOSE: The purpose of this study was to determine the physiologic effects of cigarette smoke exposure and dietary cholesterol on the availability of nitric oxide in aortic vascular rings. METHODS: Four groups of New Zealand White rabbits were placed in an air flow chamber for 3 hours per day for 8 weeks. Two of these groups were exposed to smoke from 600 cigarettes per day 5 days a week added to the chamber inflow by a robotic smoke generator. One of these groups was made hypercholesterolemic by being fed a 0.3% cholesterol diet. Two groups of rabbits were similarly placed in the air flow chamber but without smoke exposure, of which one group was also made hypercholesterolemic. After an 8-week period, the rabbits were killed and the infrarenal aortas were excised. The vessels were cut into 3 mm rings and suspended from tension transducers. The rings were contracted with potassium chloride to determine vessel integrity. Then one ring from each aorta was maximally contracted with norepinephrine, and the experimental ring was contracted to 50% of maximum. Relaxation of the rings in response to incremental doses of acetylcholine was measured. RESULTS: No significant differences were seen in contraction to potassium chloride or norepinephrine in any group. A significant decrease in acetylcholine-mediated relaxation was seen only in the smoke-exposed, cholesterol-fed group. CONCLUSIONS: Endothelial damage, as measured by acetylcholine-mediated vasorelaxation, occurs in the infrarenal aorta in rabbits that are exposed to both cigarette smoke and elevated dietary cholesterol. Cigarette smoke exposure alone or hypercholesterolemia alone in this model did not result in significant alteration in acetylcholine-mediated vasorelaxation.

Acetylcholine↗
PubMed1997

The importance of cellular environment to function of the CD44 matrix receptor.

Much has been learned recently by experimental manipulation of the structure of CD44 and assessment of the resulting functions. However, even greater structural variation is naturally introduced by CD44-bearing cells. A structural model is now available for the portion of CD44 that recognizes hyaluronan, but it is clear that all domains of the molecule influence CD44 functions.

Animals↗
PubMed1997

Attitudes of the critically ill toward prolonging life: the role of social support.

Desires to prolong life were investigated in a hospitalized sample of 212 persons over age 50 whose illnesses were severe and who had an average life expectancy of six to twelve months. The importance of social support was emphasized in defining the context in which the stressors of unfinished business and fear of death prompted desires to prolong life. Interactions existed in predicting desires for prolonging life based on ethnicity and whether respondents did or did not have sustained family contact. Family contact and salience increased the desire to live longer for African Americans, but not for Whites.

Aged↗
PubMed1996

A prospective study of the impact of patient preferences on life-sustaining treatment and hospital cost.

OBJECTIVES: Ethicists advise that life-sustaining treatment decisions should be made in keeping with patient preferences. Until recently, there has been little systematic study of the impact of patient preferences on the use of various life-sustaining treatments or the consequent cost of hospital care. This prospective study was designed to answer the following questions: a) Do patient treatment preferences about the use of life-sustaining treatment influence the treatments they receive? and b) Do patient treatment preferences influence the total cost of their hospitalization? DESIGN: A prospective, cohort study. SETTING: A university teaching hospital. PATIENTS: Hospitalized patients, at least 50 yrs of age, with short life expectancy due to end-stage heart, lung, or liver disease, metastatic cancer, or lymphoma. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Patients were interviewed to determine their desire for life-sustaining treatment and other characteristics and then were followed for 6 months to determine life-sustaining treatment use and costs during hospitalization. Two hundred forty-four patients were interviewed. Fifty-eight percent of patients expressed a desire for life-sustaining treatments to prolong life for 1 wk. During 245 subsequent hospitalizations, there were 20 episodes of mechanical ventilation, 63 episodes of intensive care, and 66 cancer treatments given. Bivariate and multivariate analyses showed no significant association between patient desire to receive treatment to prolong life and either life-sustaining treatment use (p = .59) or hospital costs (p = .20). CONCLUSION: In a university teaching hospital setting, there is no systematic evidence that patient preferences determine life-sustaining treatment use or hospital costs.

Aged↗
PubMed1995

Oral contraceptives and breast cancer risk among younger women.

BACKGROUND: Several studies have suggested a link between oral contraceptive use and breast cancer in younger women, but it is possible that chance or bias, including selective screening of contraceptive users, contributed to the putative association. PURPOSE: Given that oral contraceptives were first marketed in the United States in the early 1960s, we conducted a population-based case-control study to examine the relationship between use of oral contraceptives and breast cancer among women in a recently assembled cohort, focusing on women younger than 45 years of age who had the opportunity for exposure throughout their entire reproductive years. METHODS: Breast cancer patients and healthy control subjects were identified, the latter group by random-digit dialing, in Atlanta, Ga., Seattle/Puget Sound, Wash., and central New Jersey. In Seattle and New Jersey, the study was confined to women 20 through 44 years of age; in Atlanta the age range was extended through 54 years. Patients included women with in situ or invasive breast cancer newly diagnosed during the period of May 1, 1990, through December 31, 1992. In-person interviews were completed by 2203 (86.4%) of 2551 eligible patients and 2009 (78.1%) of 2571 eligible control subjects. Analyses focused on women younger than 45 years of age (1648 patients and 1505 control subjects) to maximize opportunities for extended exposure. Logistic regression analyses were used to obtain maximum likelihood estimates of relative risks (RRs) and their 95% confidence intervals (CIs). RESULTS: Among women younger than 45 years, oral contraceptive use for 6 months or longer was associated with an RR for breast cancer of 1.3 (95% CI = 1.1-1.5). Risks were enhanced for breast cancers occurring prior to age 35 years (RR = 1.7; 95% CI = 1.2-2.6), with the RR rising to 2.2 (95% CI = 1.2-4.1) for users of 10 or more years. The RR for breast cancer for those whose oral contraceptive use began early (before age 18 years) and continued long-term (> 10 years) was even higher (RR = 3.1; 95% CI = 1.4-6.7). The RRs observed for those who used oral contraceptives within 5 years of cancer diagnosis were higher than for those who had not, with the effect most marked for women younger than age 35 years (RR = 2.0; 95% CI = 1.3-3.1). Oral contraceptive associations were also strongest for cancers diagnosed at advanced stages. Evaluation of screening histories and methods of diagnosis failed to support the speculation that associations could be due to selective screening. Among women 45 years of age and older, no associations of risk with use of oral contraceptives were noted. CONCLUSIONS: The relationship between oral contraceptives and breast cancer in young women appears to have a biologic basis rather than to be an artifact or the result of bias.

Adult↗
PubMed1992

Is trichomoniasis often associated with bacterial vaginosis in pregnant adolescents?

The same criteria for identifying bacterial vaginosis are often present in women with trichomoniasis. These criteria include elevated vaginal pH, vaginal odor, homogeneous discharge, increased anaerobic bacteriologic vaginal flora, and elevated levels of bacterial enzymes. Clinically mixed vaginal infections occur, and because the treatment for these two conditions can be different, it is important to distinguish between them. Trichomoniasis can interfere with a Gram stain diagnosis or the proline aminopeptidase test for bacterial vaginosis. Clue cells are not generally found in women with Trichomonas vaginalis, but when present, they strongly indicate the concomitant presence of bacterial vaginosis.

Adolescent↗
PubMed1992

Invasive cervical cancer following cryotherapy for cervical intraepithelial neoplasia or human papillomavirus infection.

OBJECTIVE: To determine the following: 1) the causes for the failure of cervical cryotherapy to prevent cervical cancer, and 2) whether cervical cryotherapy is associated with the development of cervical adenocarcinoma rather than squamous carcinoma. METHODS: We reviewed the medical charts of 327 women with cervical cancer. One hundred forty-seven for whom pertinent history was missing were contacted by telephone or at clinic visits. History obtained verbally was confirmed by outside medical records. Cervical biopsies (N = 16) and endocervical curettages (ECCs) (N = 15) performed before cryotherapy and biopsies at the diagnosis of cancer (N = 21) were reviewed. RESULTS: Twenty-one women with cervical cancer had a history of cryotherapy for cervical intraepithelial neoplasia (CIN) or human papillomavirus infection (HPV). The interval between cryotherapy and cancer was more than 2 years in 19 and more than 5 years in ten. Several categories of pre-treatment errors were identified. Evaluation before cryotherapy was appropriate in only nine cases. Interpretive errors were noted in three of 16 cervical biopsies and ten of 15 ECCs. After cryotherapy, 12% of women had appropriate follow-up. Of the invasive cancers that developed, 24% in the cryotherapy group and 21% in the non-cryotherapy group were adenocarcinomas. CONCLUSIONS: Careful evaluation before cryotherapy, accurate pathology reports, and consistent long-term follow-up are necessary if cryotherapy is to be used to treat CIN or HPV. We found no evidence that cryotherapy is associated with the development of cervical adenocarcinoma.

Adenocarcinoma↗
PubMed1991

Efficacy and safety of alprazolam, imipramine and placebo in treating panic disorder. A Scandinavian multicenter study.

As part of the cross-national collaborative panic study, a double-blind comparison of alprazolam, imipramine and placebo was performed in Scandinavian outpatients with panic disorder according to DSM-III; 41 patients were randomly allocated to each drug. Doses were increased for 3 weeks to an average of about 6 mg alprazolam, 150 mg imipramine and a corresponding number of placebo capsules, which were then given for 5 weeks. No more than supportive psychotherapy was given. Key symptoms were rated weekly. The drugs were tapered for 4 or 8 weeks and the patients were followed up for 6 months. Compliance at 3 weeks was 95% for alprazolam, 83% for imipramine and 88% for placebo; at 8 weeks 95% for alprazolam, 73% for imipramine and 46% for placebo. At 3 weeks plasma determination showed that the proportion taking diazepam outside the protocol was 0% for alprazolam, 19% for imipramine and 31% for placebo; at 8 weeks the corresponding proportions were 3%, 11% and 16%. Intention-to-treat analysis showed that freedom from panic attacks was obtained for 68% with alprazolam, 61% with imipramine and 34% with placebo. Alprazolam was more effective than imipramine and placebo on anticipatory anxiety and phobic symptoms. Globally rated by physicians and patients, about 60% had complete remission with alprazolam and imipramine and 30% on placebo. At least partial remission was obtained in about 85% with alprazolam, 70% with imipramine and 40% with placebo. Alprazolam had a more rapid onset of action than imipramine on all symptoms. Side effects were generally mild, with a preponderance of drowsiness for alprazolam and anticholinergic effects for imipramine. Tapering was uneventful without significant discontinuation phenomena. During taper and follow-up, several patients in remission relapsed, leaving approximately 30% patients in complete remission in all groups. To obtain more stable improvement, either long-term drug treatment or combinations of drug treatment and psychotherapy should be evaluated.

Adolescent↗