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Biomedical subjects

M Gross

Publications and source records attributed to M Gross.

At least 145 records · Page 8Linked to original sources
PubMed2000

[67-year-old patient with upper gastrointestinal bleeding]

A 67-year-old patient with upper gastrointestinal bleeding. HISTORY AND CLINICAL FINDINGS: A 67-year old patient with melaena and anaemia (haemoglobin 4.8 g/dl) for 14 days had been admitted to hospital under suspicion of upper gastrointestinal bleeding. The patient had a history of 2/3 resection of the stomach for recurrent duodenal ulcer and of a right nephrectomie for hypernephroma 18 years ago. There was no abdominal pain on pressure, nor muscular guarding. INVESTIGATIONS: Endoscopy (oesophago-duodenoscopie, coloscopie), radiography (angiography, gastrografin passage) and ultrasound failed to locate the source of bleeding. TREATMENT AND COURSE: After repeated endoscopic attempts to localize the source of bleeding and growing need of transfusions (12 blood-concentrates in 5 days) an exploratory laparotomie was done. Surprisingly a bleeding fistula between the stump of the right renal arteria and duodenum was found. The defects were excised and directly closed. CONCLUSIONS: Secondary aortoduodenal fistula after nephrectomy is rare. If the source of bleeding can't be found, and there is in any doubt an exploratory laparotomy should be done.

Journal Article↗
PubMed2000

Ground state of a dipolar crystal

We provide some of the strongest evidence to date that the ground state structure of an infinite collection of point dipoles with hardcore sphere interactions is body-centered tetragonal. The structure with the next highest binding energy is not face-centered cubic; a particular honeycomb structure has lower energy.

Journal Article↗
PubMed2000

Synergistic effects of AT(1) and ET(A) receptor blockade in a transgenic, angiotensin II-dependent, rat model.

Angiotensin II and endothelin may participate in increasing blood pressure and inducing end-organ damage, but the evidence is conflicting. We tested the hypothesis that endothelin(A) receptor blockade would ameliorate blood pressure and end-organ damage in a rat model of human renin-dependent hypertension. We studied rats that were transgenic for both the human renin and angiotensinogen genes. Experimental groups (n=12 each) of untreated transgenic rats, transgenic rats receiving subdepressor doses of losartan (10 mg/kg), transgenic rats receiving LU 135252 (30 mg/kg), transgenic rats receiving both drugs, and nontransgenic rats were studied between 6 to 10 weeks of age. Blood pressure was measured with tail-cuff sphygmomanometry. Gene expression for atrial natriuretic peptide, collagen III, and ACE was measured. The mortality rate in untreated transgenic rats was 42%, which is consistent with previous observations in this line. Single losartan or LU 135252 treatment reduced mortality incidence to 1 rat per group (8%), without significantly lowering blood pressure. In the combination group, blood pressure was normalized and all rats survived. The drug combination also decreased elevated water intake in transgenic rats to normal levels and significantly reduced cardiac hypertrophy. Furthermore, the combination of drugs decreased cardiac atrial natriuretic peptide, ACE gene, and renal collagen III gene expression. We suggest that endothelin participates in this model of angiotensin II-induced hypertension and end-organ damage. Our findings may have clinical implications and provide a rationale for combining angiotensin II type 1 receptor and endothelin(A) receptor blockade to obtain a synergistic effect.

Angiotensin II↗
PubMed2000

Proteins that convert from alpha helix to beta sheet: implications for folding and disease.

The sequence of a protein normally determines which amino acid residues will form alpha helices, and which one beta sheets, to an extent that allows secondary structure prediction to be made with a reasonable reliability. Nevertheless, non-native helical structures are observed during in vitro folding of several model proteins and may even occur during protein biosynthesis within the ribosomal exit tunnel. Moreover, non-native beta sheet structures are common in amyloid fibrils formed by a variety of pathogenic and even non-pathogenic proteins and peptides. In all of these cases, the formation of alpha helix precedes the appearance of beta sheet, which suggests that conversion from the simpler, more local helix structure to the often more convoluted sheet architecture during folding and pathogenic misfolding processes could be a unifying principle of general importance. A better understanding of this switching process, and the ability to design molecular systems which can be induced to switch between these conformations will have a significant impact on fields ranging from fundamental biochemistry through to applied technology and medicine.

Amino Acid Sequence↗
PubMed2000

Feasibility of chemoprophylaxis studies in high risk HIV-seronegative populations.

Administration of antiretroviral medications-recommended to prevent HIV infection after occupational exposure-has not been evaluated for safety or efficacy following nonoccupational exposure. HIV-seronegative persons at increased risk for HIV exposure completed a self-administered questionnaire assessing their willingness to join studies of this approach. Of 4,572 respondents, 60% were willing to join a study of a "morning-after" pill; dosing three times a day and mild side effects reduced willingness to 30%. Men who have sex with men (MSM) who reported unprotected anal intercourse in the prior 6 months were significantly more likely to be willing to join a morning-after study than MSM who did not (p = 0.006). MSM favored a preventive HIV vaccine over oral chemoprophylaxis; other populations preferred oral chemoprophylaxis. Interest in studies declined as the hypothetical regimen became more demanding. Studies must emphasize the unknown efficacy of this approach, given increased interest among MSM at greater risk of exposure.

AIDS Vaccines↗
PubMed2000

Increasing vegetable and fruit intake: randomized intervention and monitoring in an at-risk population.

High vegetable and fruit (V&F) consumption has been associated with a lower risk of several cancers. However, little is known about the ability of individuals to increase their intakes markedly. In this 1-year randomized, controlled diet intervention study of men and women with a recent history of adenomas, the intervention group (n = 100) was asked to increase V&F intake to at least eight servings per day; the control group (n = 101) continued eating their usual diet. End-point measures included V&F intake assessed by 3-day diet records, plasma carotenoids, serum lipids, urinary sodium and potassium, and body weight. The intervention group increased their daily V&F intake an average of 5.5 servings over 1 year; the control group had an average decrease of 0.5 servings per day (P < 0.001). Plasma total carotenoids, alpha-carotene, beta-carotene, beta-cryptoxanthin, and lutein/zeaxanthin were each statistically significantly elevated over baseline (11-54%) in the intervention group compared with the control group over the duration of follow-up (P < 0.001). Urinary potassium excretion was elevated 14% over baseline in the intervention group compared with no change in the control group (P < 0.001). Modest decreases in the intervention but not the control group were observed for total and low-density lipoprotein cholesterol. Plasma lycopene, triglycerides, high-density lipoprotein cholesterol, body weight, and urinary sodium were not affected by the intervention. V&F intake was significantly increased in this motivated population at higher risk of colon cancer and maintained for at least 12 months, as assessed using diet records and an ensemble of biomarkers.

Adenoma↗
PubMed2000

Closed tibial shaft fractures: management and treatment complications. A review of the prospective literature.

OBJECTIVE: To compare the results and complications of the various modalities for treating closed fractures of the tibial shaft described in the prospective literature. DATA SOURCES: A MEDLINE search of the English language literature from 1966 to 1999 was conducted using the MeSH heading "tibial fractures." Studies pertaining to the management of closed tibial shaft fractures were reviewed, and their reference lists were searched for additional articles. STUDY SELECTION: An analysis of the relevant prospective, randomized controlled trials was performed. Studies including confounding data on open fractures or fractures in children were excluded. The 13 remaining studies were reviewed. DATA EXTRACTION: Raw data were extracted and pooled for each method of treatment. DATA SYNTHESIS: The 13 studies described 895 tibial shaft fractures treated by application of a plaster cast, fixation with plate and screws, and reamed or unreamed intramedullary nailing. Although definitions varied, the combined incidence of delayed and nonunion was lower with operative treatment (2.6% with plate fixation, 8.0% with reamed nailing and 16.7% with unreamed nailing) than with closed treatment (17.2%). The incidence of malunion was similarly lower with operative treatment (0% with plate fixation, 3.2% with reamed nailing and 11.8% with unreamed nailing) than with closed treatment (31.7%). Superficial infection was most common with plate fixation (9.0%) compared with 2.9% for reamed nailing, 0.5% for unreamed nailing and 0% for closed treatment. The incidence of osteomyelitis was similar for all groups. Rates of reoperation ranged from 4.7% to 23.1%. CONCLUSIONS: All forms of treatment for tibial shaft fractures are associated with complications. A knowledge of the incidence of each complication facilitates the consent process. To fully resolve the controversy as to the best method of treatment, a large, randomized, controlled trial is required. This review more precisely predicts the expected incidence of complications, allowing the numbers of required patients to be more accurately determined for future randomized controlled studies.

Adult↗
PubMed2000

N-Acetyltransferase-2 genetic polymorphism, well-done meat intake, and breast cancer risk among postmenopausal women.

Heterocyclic amines found in well-done meat require host-mediated metabolic activation before initiating DNA mutations and tumors in target organs. Polymorphic N-acetyltransferase-2 (NAT2) catalyzes the activation of heterocyclic amines via O-acetylation, suggesting that NAT2 genotypes with high O-acetyltransferase activity (rapid/intermediate acetylator phenotype) increase the risk of breast cancer in women who consume well-done meat. To test this hypothesis, DNA samples and information on diet and other breast cancer risk factors were obtained from a nested case-control study of postmenopausal women. Twenty-seven NAT2 genotypes were determined and assigned to rapid, intermediate, or slow acetylator groups based on published characterizations of recombinant NAT2 allozymes. NAT2 genotype alone was not associated with breast cancer risk. A significant dose-response relationship was observed between breast cancer risk and consumption of well-done meat among women with the rapid/intermediate NAT2 genotype (trend test, P = 0.003) that was not evident among women with the slow acetylator genotype (trend test, P = 0.22). These results suggest an interaction between NAT2 genotype and meat doneness, although a test for multiplicative interaction was not statistically significant (P = 0.06). Among women with the rapid/intermediate NAT2 genotype, consumption of well-done meat was associated with a nearly 8-fold (odds ratio, 7.6; 95% confidence interval, 1.1-50.4) elevated breast cancer risk compared with those consuming rare or medium-done meats. These results are consistent with a role for O-acetylation in the activation of heterocyclic amine carcinogens and support the hypothesis that the NAT2 acetylation polymorphism is a breast cancer risk factor among postmenopausal women with high levels of heterocyclic amine exposure.

Acetylation↗
PubMed2000

Outcome results after total knee arthroplasty: does the patient's physical and mental health improve?

An ongoing prospective study with continuing enrollment and follow-up of 279 patients analyzed the postoperative mental and physical outcomes on an interim basis using the SF-36 Physical and Mental Health Summary Scale, which allows for patient self-assessment of total knee arthroplasty (TKA) outcome. Results of this study support the hypothesis that patients can assess their own physical health after surgery and suggest that while physical health component scores increased dramatically subsequent to TKA, mental health component scores remained essentially unchanged. The lack of significant improvement of the mental health component score can be explained in part by noting that the mean mental health component score for the study patient cohort was already above average preoperatively. Thus, mental health component scores did not correlate with the dramatic improvement of physical health component scores. Physical health component score appears to be a more accurate indicator of the benefits of TKA than mental health component score.

Adult↗
PubMed2000

Vasculopathy and amyloid beta reactivity in brains of patients with acquired immune deficiency (AIDS).

The authors examined multiple brain sections from 15 autopsy cases of AIDS for the vascular changes, presence of amyloid plaques and signs of axonal damage. The mean patients age was 33.8 years (range 24-48 years). Neuropathological findings included: HIV-specific changes (5), opportunistic infections (7), lymphoma (1) and two cases with nonspecific changes. All sections were stained with hematoxylin-eosin (H-E), selected sections were stained with Masson trichrome, Gomori reticulin, Congo red and thioflavine S method. Two sections from each case were immunostained for the presence of beta-amyloid (4G8). ubiquitin, alpha-smooth muscle actin and CD31. The different forms of vascular changes were found in all cases. The common changes were: lymphocytic perivascular or transmural infiltrations and hyalinization, thickening or fibrosis of the arterial and arteriolar wall. The perivascular space widening up to status lacunaris was a frequent phenomenon in the basal ganglia and deep white matter. Some of the cortical arterioles formed little multiluminal structures. Immunohistochemical examination revealed features of hypertrophy of the vascular muscular layer and signs of the slight endothelial cells proliferation. In three cases 4G8 immunopositive. Congo red and thioflavine S-negative, diffuse beta-amyloid deposits were present in the gray matter, focally their localization was perivascular. Ubiquitin immunoreactivity presented as numerous dot-like structures or focal bundles of positive widened axons in the white matter, spheroids and scattered positive neurons were also found. The authors suggest that some of morphological changes within the brain and consecutive neuropsychological symptoms in AIDS are of the vascular origin. Presence of amyloid plaques and axonal damage are the elements of the complex degenerative and inflammatory process in the brain caused by chronic inflammatory stimulation in HIV infection.

AIDS Dementia Complex↗