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Biomedical subjects

M Fisher

Publications and source records attributed to M Fisher.

At least 343 records · Page 19Linked to original sources
PubMed1992

Reversible focal ischemic injury demonstrated by diffusion-weighted magnetic resonance imaging in rats.

BACKGROUND AND PURPOSE: Diffusion-weighted magnetic resonance imaging (DWI) can quantitatively display focal brain abnormalities within minutes after the onset of ischemia. We performed the present study to determine the effects of 1 and 2 hours of temporary ischemia on DWI. METHODS: We examined DWI and T2-weighted magnetic resonance images (T2WI) during and after 1 and 2 hours of temporary middle cerebral artery occlusion in rats (n = 10 for each group). In a subgroup of four animals from each group, we employed perfusion magnetic resonance imaging to monitor cerebral perfusion. Neurological outcome and infarct size after survival for 24 hours were compared between the groups and correlated with DWI and T2WI studies. RESULTS: Perfusion studies qualitatively documented hypoperfusion and reperfusion during and after temporary occlusion. Lesion size on DWI during reperfusion was significantly less than that during ischemia for 1 (55% decline, p less than 0.02) but not 2 hours of occlusion. The DWI signal intensity ratio (intensity compared with that in the contralateral homologous area) just before withdrawal of the occluder was significantly less in regions where the hyperintensity disappeared after withdrawal than in regions with persistent hyperintensity (p less than 0.002). The T2WI studies revealed few or no abnormalities, except after 2 hours of occlusion. The neurological outcome was significantly better in the 1-hour than in the 2-hour group (p less than 0.05). Postmortem infarct volume was significantly smaller in the 1-hour group than in the 2-hour group (p less than 0.05). The postwithdrawal DWI accurately predicted infarct size (R = 0.96, p less than 0.0001). CONCLUSIONS: The present study indicates that DWI can rapidly display not only irreversible but also reversible ischemic brain damage and enhances the importance of DWI as a diagnostic modality for stroke.

Animals↗
PubMed1992

Diffusion-weighted magnetic resonance imaging: rapid and quantitative detection of focal brain ischemia.

We examined serial changes of diffusion- (DWI) and T2-weighted (T2WI) magnetic resonance images 30 minutes to 3 hours after intraluminal suture occlusion of the middle cerebral artery (MCA) in eight rats and after sham occlusion in four. We correlated the abnormal areas on DWI and T2WI with postmortem areas of infarction determined by 2,3,5-triphenyltetrazolium chloride (TTC), 24 hours after the operation. The 30-minute DWI in each MCA-occluded rat demonstrated increased signal intensity in the ipsilateral MCA territory, while T2WI showed no changes. At 3 hours, the ipsilateral DWI signal intensity increased further and the area of abnormality slightly increased. In some animals, the 3-hour T2WI disclosed an area of hyperintensity significantly smaller than that seen on the 30-minute DWI. TTC staining demonstrated an extensive MCA infarction in all rats with permanent MCA occlusion, confirmed by hematoxylin and eosin staining. The percent infarcted area of coronal brain sections, as determined by TTC staining, correlated significantly with areas on similar DWI sections at both 30 minutes and 3 hours. Sham-occluded control animals did not display any changes on DWI, T2WI, or TTC staining. The present study suggests that DWI is a very sensitive modality for detecting early ischemic brain injury, being highly correlated with post-mortem area of infarction, and may be useful to assess pharmacologic intervention.

Animals↗
PubMed1992

Giant T-wave inversion in patients with acute coronary insufficiency.

We have observed an electrocardiographic (ECG) pattern of deep T-wave or "giant T wave" inversion in patients with acute coronary insufficiency. We reviewed the ECGs of 936 patients admitted to our coronary care unit during a one-year period. We found the pattern of giant T-wave inversion was present in nine patients (1 percent). We examined the echocardiograms of all of these patients and we analyzed the coronary angiograms on the seven patients in whom it was performed. We found that giant T-wave inversion was usually found in patients with stenosis in the left coronary system. In addition, the majority of these patients also had echocardiographic evidence of left ventricular hypertrophy. We conclude that the high frequency of a partially patent vessel in the left coronary system suggests that this ECG pattern may be useful in identifying patients who might benefit from coronary revascularization.

Acute Disease↗
PubMed1992

The Role of Barrier Contraceptives in Prevention of Pregnancy and Disease in Adolescents.

The advent of HIV infection and a greater understanding of the effects of other viral sexually transmitted diseases have brought condoms back to the forefront in discussions of contraception in both the general press and the medical literature. Development of several newer barrier methods and improved understanding of use of the older methods by adolescents have occurred during the past few years.

Journal Article↗
PubMed1992

Medical Complications of Anorexia and Bulimia Nervosa.

Medical complications of anorexia and bulimia nervosa may include metabolic, renal, gastrointestinal, cardiovascular, pulmonary, endocrinologic, neurologic, hematologic, immunologic, dental, and/or dermatologic effects. Patient evaluation and differential diagnosis must keep all of these possibilities in mind if the adolescent with an eating disorder is to be successfully treated.

Journal Article↗
PubMed1992

Parents' views of adolescent health issues.

To determine how important the parents of teenagers consider adolescent health issues to be and the kind of involvement they would like from their schools and physicians, a questionnaire was sent to 1090 families with children attending two public high schools in a suburban community. The 438 parents who completed the questionnaire (40% response rate) indicated that their adolescents had a mean age of 16.2 years, 52% were male, 54% were in grades 11 and 12, and 70% received regular care from a pediatrician. Most parents considered substance use, sexuality, mental health issues, nutritional concerns, and general medical issues to be issues requiring attention nationally; many considered these issues to require attention locally; fewer considered these issues to require attention for their teenager's friends; and only some indicated these issues require attention for their own teenagers. More than 95% of respondents said parents should discuss these topics with their teenagers, more than 80% said they themselves did, and more than 85% said they wanted these issues discussed with their adolescents in school. Approximately three quarters of parents said that they would bring their adolescent to their regular doctor for management of these issues, expected that their physician would be comfortable with such care, and wanted their doctor to discuss these issues with their teenagers.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

Regional distribution of thrombomodulin in human brain.

Thrombomodulin, an integral membrane protein with important anticoagulant properties, was evaluated for its distribution in blood vessels of human brain. Adjacent sections from frozen human brain were stained for von Willebrand Factor (an endothelium marker) or thrombomodulin. The number of thrombomodulin-positive blood vessels was expressed as a percentage of all blood vessels in a specific area. The density ratio was compared among cortical and subcortical regions in the human brain. Our results indicated that thrombomodulin density in neocortex, cerebellum, medulla and hippocampus was similar. There was, however, significantly less thrombomodulin in putamen (P less than 0.01), pons (P less than 0.001) and mesencephalon (P less than 0.001) compared to neocortex. The regional distribution of thrombomodulin may prove to be helpful for understanding the development of thrombotic diseases of the brain.

Adult↗
PubMed1991

Increased tumorigenicity of fibronectin receptor deficient Chinese hamster ovary cell variants.

We have developed a series of variant clonal Chinese hamster ovary cell sublines which are deficient in the expression of the alpha 5/beta 1 integrin fibronectin receptor. When these clonal sublines were injected s.c. into nude mice, there were marked differences in the rate of tumor growth. Tumors from clones expressing very low levels of fibronectin receptor grew most rapidly, clones expressing levels of fibronectin receptor comparable to wild type cells grew at an intermediate rate, while a clone expressing elevated levels of fibronectin receptor grew slowly. Cells recovered from the tumors maintained their original phenotypes in terms of levels of fibronectin receptor expression. These results suggest that there is an inverse correlation between the level of expression of the alpha 5/beta 1 fibronectin receptor and the rate of tumor growth.

Animals↗
PubMed1991

A 21-aminosteroid inhibits oxidation of human low density lipoprotein by human monocytes and copper.

Oxidation of low density lipoprotein (LDL) leads to more rapid uptake by arterial wall macrophages and foam cell formation. Inhibiting LDL oxidation may impede these processes and offers a new mechanism to retard atherogenesis. The 21-aminosteroids, derived from methylprednisolone, are potent inhibitors of free radical production by stimulated monocytes and also are scavengers of lipid peroxyl radicals. The 21-aminosteroid, U74500A, was added to a mixture of low density lipoprotein cholesterol and human monocytes to which lipopolysaccharide was add to stimulate the monocytes. At a final concentration of 10 microM, U74500A reduced the production of lipid peroxidation from 6.10 +/- 1.11 to 0.84 +/- 0.16 nmol (mean +/- SEM) MDA equivalent/1 x 10(6) monocytes, as measured by a thiobarbituric acid reacting substance (TBARS) assay. Similarly 10 microns U74500A reduced Cu2+ induced LDL oxidation from 12.28 +/- 0.10 (in vehicle) to 0.49 +/- 0.12. These observations suggest that the 21-aminosteroids should be evaluated in animal models as a potential therapy to retard atherogenesis, especially considering their apparent lack of mineralocorticoid and glucocorticoid side-effects.

Copper↗
PubMed1991

Eating attitudes, health-risk behaviors, self-esteem, and anxiety among adolescent females in a suburban high school.

In order to determine whether adolescent females with abnormal eating attitudes display lower levels of self-esteem and higher levels of anxiety than their peers, and whether these adolescents participate in health-risk behaviors to a greater or lesser degree than their peers, we administered a series of questionnaires to the females attending a suburban high school in New York State. The questionnaires, completed by 268 students (mean age, 16.2 years), included data on health-risk behaviors and weight attitudes, an Eating Attitudes Test, a self-esteem scale, and an anxiety inventory. Results indicated that almost two-thirds of the students described themselves as overweight, almost three-quarters felt they were above the healthiest weight for their age and height, and almost four-fifths were above the weight at which they would be most happy; 18% of the students scored 30 or more on the Eating Attitudes Test, a score suggestive of an eating disorder. Use of Spearman-rank correlation coefficients and multiple linear regression analysis revealed that those with more unhappiness with their weight and higher scores on the eating attitudes test were more likely to have lower self-esteem and higher anxiety and to participate more in health-risk behaviors, including cigarette smoking, alcohol use, drug use, and sexual activity with more total partners. The data from this study further corroborate the growing belief that health-risk behaviors tend to cluster together in vulnerable adolescents and demonstrate that abnormal eating attitudes and behaviors may be part of this cluster, especially in females with low self-esteem and high levels of anxiety.

Adolescent↗
PubMed1991

Cervicovaginal human papillomavirus infection in suburban adolescents and young adults.

To investigate the prevalence rates of and risk factors for genital human papillomavirus (HPV) infection in white, middle-class adolescents, we obtained specimens for HPV from 107 patients undergoing pelvic examination at a suburban adolescent health service. Specimens were obtained by means of cervicovaginal lavage and were analyzed for HPV DNA by Southern blot analysis. The subjects' mean age was 18.5 (+/- 2.0 SD) years; 47% of the subjects were seen for contraception, 36% for possible pregnancy, 12% for a gynecologic complaint, and 5% for a general examination. We detected HPV in 32% of patients; HPV types included 6/11 (6%), 16 (3%), 18 (15%), 31 (3%), 42 (6%), 45 (18%), and 56 (6%). The DNA type was classified as uncharacterized in 47%, and 3% had more than one type. Univariate analysis revealed that patients found to have HPV were more likely to have more than two sexual partners, to have been sexually active for more than 2 years, to have had menarche before 12 years of age, and to have a history of sexually transmitted disease; logistic regression multivariate analysis demonstrated that number of partners and age at menarche were independent risk factors for HPV. These data indicate that HPV is common among sexually active teenagers regardless of ethnicity or socioeconomic status. The association of cervicovaginal HPV infection with sexual activity further supports the notion of the sexual transmission of this agent.

Adolescent↗
PubMed1991

Diabetic end stage renal failure--the Wellington experience 1975-1988.

Since the late 1970s patients with diabetic nephropathy have formed an increasing proportion of new entrants to the Hospital renal dialysis and transplantation programme, reaching 28% for the three year period to December 1988. Between 1 January 1975 and 31 December 1988, 87 diabetic patients were accepted for treatment. Fifty-one per cent were European, predominantly type I diabetics. Maori (9% of the total reference population) accounted for a disproportionately high 47% due to an over-representation by type II diabetic patients (34 of 41 Maori). These findings cannot be explained by the higher prevalence in Maori of type II diabetes but appear to be due to a more prevalent and/or aggressive diabetic renal lesion in this group. On commencing treatment, nearly all patients had retinopathy and the majority had evidence of peripheral vascular disease, hypertension and neuropathy. CAPD was the initial mode of renal replacement therapy in 70% of patients. Overall patient survival was 77% at one year and 42% at three years, and survival on CAPD was 76% and 37% at one and three years, respectively. Patient survival on transplantation was 63% at one year and 58% at three years. Graft survival was 51% at one year and 46% at three years. Although the short term outlook for diabetic patients on renal replacement therapy is encouraging, longer term survival compared to non-diabetic patients is poor. Vascular disease is the major cause of death and an important factor in patient morbidity.

Adult↗
PubMed1991

Thrombosis in a congenitally bifurcated superior sagittal sinus.

A 26-year-old woman had a peripartum venous thrombotic stroke involving the right parietal lobe. The initial thrombus was present only in the right channel of a congenitally bifurcated superior sagittal sinus. This diagnosis and subsequent thrombus extension were readily shown by magnetic resonance imaging in contrast to equivocal angiography. A subsequent, prospective review of 100 patients undergoing cranial magnetic resonance imaging showed the presence of similarly bifurcated superior sagittal sinuses in two. The patient stabilized after therapy with intravenous heparin, but switching her medication to oral warfarin sodium was followed by clinical deterioration and propagation of the thrombus, necessitating resumption of intravenous heparin. No coagulopathy was identified.

Adult↗
PubMed1991

Immunohematologic characteristics of infection-associated cerebral infarction.

We evaluated 50 consecutive patients with acute ischemic stroke to assess the prevalence of systemic infection preceding the neurological event. We analyzed the immunohematologic characteristics of patients with and without signs and/or symptoms of a preceding infectious process. Patients were examined less than or equal to 7 days after cerebral infarction and evaluated for fibrinogen, anticardiolipin antibodies, fibrin D-dimer (a fragment of cross-linked fibrin), plasminogen activator inhibitor-1, and protein S. Of the 50 patients, 17 had symptoms of infection beginning less than or equal to 1 month before the stroke (11 had upper respiratory tract infections, three urinary tract infections, two subacute bacterial endocarditis, and one pneumonia). Compared with patients without infection, patients with infection had significant increases in fibrin D-dimer concentration (5.3 +/- 1.1 versus 4.7 +/- 0.9 log-transformed ng/ml, p less than 0.05) and cardiolipin immunoreactivity, IgG isotype (1.8 +/- 1.3 versus 1.1 +/- 0.9 log-transformed phospholipid units, p less than 0.04), and, when studied less than or equal to 2 days after the stroke, increased fibrinogen levels (459 +/- 126 versus 360 +/- 94 mg/dl, p less than 0.05). In conclusion, infection-associated cerebral infarction is common and is associated with substantial immunohematologic abnormalities.

Adult↗