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Biomedical subjects

V Davis

Publications and source records attributed to V Davis.

At least 19 recordsLinked to original sources
PubMed2001

A major role for VCAM-1, but not ICAM-1, in early atherosclerosis.

VCAM-1 and ICAM-1 are endothelial adhesion molecules of the Ig gene superfamily that may participate in atherogenesis by promoting monocyte accumulation in the arterial intima. Both are expressed in regions predisposed to atherosclerosis and at the periphery of established lesions, while ICAM-1 is also expressed more broadly. To evaluate functions of VCAM-1 in chronic disease, we disrupted its fourth Ig domain, producing the murine Vcam1(D4D) allele. VCAM-1(D4D) mRNA and protein were reduced to 2-8% of wild-type allele (Vcam1(+)) levels but were sufficient to partially rescue the lethal phenotype of VCAM-1-null embryos. After crossing into the LDL receptor-null background, Vcam1(+/+) and Vcam1(D4D/D4D) paired littermates were generated from heterozygous intercrosses and fed a cholesterol-enriched diet for 8 weeks. The area of early atherosclerotic lesions in the aorta, quantified by en face oil red O staining, was reduced significantly in Vcam1(D4D/D4D) mice, although cholesterol levels, lipoprotein profiles, and numbers of circulating leukocytes were comparable to wild-type. In contrast, deficiency of ICAM-1 either alone or in combination with VCAM-1 deficiency did not alter nascent lesion formation. Therefore, although expression of both VCAM-1 and ICAM-1 is upregulated in atherosclerotic lesions, our data indicate that VCAM-1 plays a dominant role in the initiation of atherosclerosis.

Animals↗
PubMed2000

Trauma and thyroid-induced tachycardia.

Excluding a source of hemorrhage after blunt trauma in a patient who presents with a sustained tachycardia can be challenging. This report is of two trauma patients presenting with undiagnosed thyrotoxicosis. Trauma-triggered thyrotoxicosis is rarely reported in the literature. The confusing presentation, the laboratory analysis, and the response to therapeutic intervention are reviewed.

Accidents, Traffic↗
PubMed1999

Oral contraceptives and smoking, current considerations: recommendations of a consensus panel.

In a closed meeting, members of the consensus panel evaluated the presentations of the scientific panel and developed a series of recommendations. They outlined clinical imperatives related to the identification and education of patients who smoke, the physician's role in smoking cessation, and the prescription of oral contraceptives for patients who smoke. They also outlined research objectives for the future. The most important suggestions include the following: All patients should be asked about their smoking status at every visit, and all smokers should be encouraged and helped to quit. The decision to prescribe an oral contraceptive requires a detailed personal and family history of thrombotic disease. Measurement of lipid profile should be considered, along with exercise and dietary intervention, for smokers >35 years old who use or request oral contraceptives. Patients >35 years old who smoke heavily (>15 cigarettes/d) should be denied the use of oral contraceptives. Preliminary data suggest that an oral contraceptive with the very low dose of 20 micrograms ethinyl estradiol may be safer for oral contraceptive users who smoke, even for those >35 years old who have an occasional cigarette, but these laboratory findings require clinical corroboration.

Cardiovascular Diseases↗
PubMed1998

Matrix metalloproteinase-2 production and its binding to the matrix are increased in abdominal aortic aneurysms.

Degradation of the elastic media is a hallmark of abdominal aortic aneurysms (AAAs). We examined the expression of 2 elastolytic matrix metalloproteinases (MMPs), MMP-2 and MMP-9, in AAA aortic tissues compared with those from atherosclerotic occlusive disease (AOD) and nondiseased control tissues. Quantitative competitive reverse transcription-polymerase chain reaction and gelatin zymography showed increased MMP-9 mRNA and protein in both AAA and AOD tissues compared with those in control tissue, but there was no significant difference between AAA and AOD. In contrast, MMP-2 mRNA and protein levels were significantly higher in AAA than in AOD or control tissues. Sequential extraction of the MMPs from the aortic tissue with a physiological salt solution, 2% dimethylsulfoxide (DMSO), and 10 mol/L urea showed that large amounts of MMP-2 and MMP-9 were bound to the matrix. The most conspicuous finding was that the levels of MMP-2 were significantly elevated in the DMSO fraction in AAA tissues compared with AOD and control tissues. In addition, a large portion of MMP-2 found in the DMSO and urea fractions was in the active 62-kDa form, indicating that the precursor of MMP-2 in AAA is largely activated locally and binds to the tissue matrix tightly. By immunolocalization, MMP-9 was found to be primarily produced by macrophages and MMP-2 by mesenchymal cells. The production of MMP-2 was prominent when mesenchymal cells were surrounded by inflammatory cells, suggesting paracrine modulation of MMP-2 expression in AAAs. These observations emphasize that MMP-2 participates in the progression of AAAs by degrading aortic tissue matrix components.

Aged↗
PubMed1997

Asian genotypes of JC virus in Native Americans and in a Pacific Island population: markers of viral evolution and human migration.

The human polyomavirus JC (JCV) causes the central nervous system demyelinating disease progressive multifocal leukoencephalopathy. Previously, we showed that 40% of Caucasians in the United States excrete JCV in the urine as detected by PCR. We have now studied 68 Navaho from New Mexico, 25 Flathead from Montana, and 29 Chamorro from Guam. By using PCR amplification of a fragment of the VP1 gene, JCV DNA was detected in the urine of 45 (66%) Navaho, 14 (56%) Flathead, and 20 (69%) Chamorro. Genotyping of viral DNAs in these cohorts by cycle sequencing showed predominantly type 2 (Asian), rather than type 1 (European). Type 1 is the major type in the United States and Hungary. Type 2 can be further subdivided into 2A, 2B, and 2C. Type 2A is found in China and Japan. Type 2B is a subtype related to the East Asian type, and is now found in Europe and the United States. The large majority (56-89%) of strains excreted by Native Americans and Pacific Islanders were the type 2A subtype, consistent with the origin of these strains in Asia. These findings indicate that JCV infection of Native Americans predates contact with Europeans, and likely predates migration of Amerind ancestors across the Bering land bridge around 12,000-30,000 years ago. If JCV had already differentiated into stable modern genotypes and subtypes prior to first settlement, the origin of JCV in humans may date from 50,000 to 100,000 years ago or more. We conclude that JCV may have coevolved with the human species, and that it provides a convenient marker for human migrations in both prehistoric and modern times.

Biomarkers↗
PubMed1997

Pathogenesis of abdominal aortic aneurysm: an update and look toward the future.

To date, aneurysm research has been primarily descriptive, reiterating the complex nature of the disease process. Enhanced by the convergence of matrix biochemistry, cell biology and immunology, this work is providing important new insight into how matrix metabolism is regulated in the diseased aorta. The focus is now on the inflammatory process and its regulation of the matrix remodeling which occurs with abdominal aortic aneurysm. A family of matrix-degrading enzymes appear to have a central role in this process. As we have learned from the evolution of the treatment of other pathologic processes such as peptic ulcer disease, the most effective pharmacologic therapies are designed from a thorough understanding of the pathophysiology of the disease. We are quickly moving forward in formulating a comprehensive understanding of the various complex interactions that result in the formation of aortic aneurysm. Given the progress of the past decade, we can expect the identification of aneurysm-associated genes and clinical trials of anti-inflammatory medications and protease inhibitors as we enter the 21st century.

Aorta, Abdominal↗
PubMed1995

How do smokers differ from nonsmokers in their response to thrombolysis? (the TIMI-4 trial)

Smokers with acute myocardial infarction appear to have a better outcome after thrombolysis than do nonsmokers. To identify factors that could contribute to this curious finding, we analyzed data from the Thrombolysis in Myocardial Infarction (TIMI-4) trial, in which 382 patients with acute myocardial infarction were randomized to tissue plasminogen activator, anistreplase, or both. Coronary angiography was performed 90 minutes and 18 to 36 hours after randomization, a myocardial perfusion scan was performed at 18 to 36 hours and before discharge, and a radionuclide ventriculogram was obtained before discharge. Angiographic and clinical outcome variables were determined in current smokers, ex-smokers, and nonsmokers, and regression analysis was used to correct for differences in baseline characteristics. The in-hospital mortality of current smokers was lower than that of ex-smokers and nonsmokers: 2.3% versus 5.2% versus 7.0%, respectively (p = 0.04 by paired comparison, current vs nonsmokers). Ninety minutes after randomization, the incidence of TIMI grade 3 flow was significantly higher in smokers than in ex-smokers and nonsmokers (55% vs 43% and 45%, p = 0.02); this difference was no longer observed at the second angiogram, nor did smokers differ from nonsmokers with respect to residual stenosis, thrombus grade, infarct size, ejection fraction, or recurrent ischemia. Because a strong inverse relation exists between TIMI grade 3 flow at 90 minutes and mortality, our findings suggest that the lower mortality of current smokers after thrombolytic therapy may be related to a higher incidence of early, complete reperfusion.

Double-Blind Method↗
PubMed1995

Targeted disruption of the murine VCAM1 gene: essential role of VCAM-1 in chorioallantoic fusion and placentation.

Vascular cell adhesion molecule-1 (VCAM-1) is expressed on vascular endothelium in a variety of inflammatory conditions and mediates leukocyte recruitment from blood into tissues. In this study we report a novel role for VCAM-1 in the formation of the umbilical cord and placenta during development. The murine VCAM1 gene was disrupted by targeted homologous recombination, and a distinct phenotype was found in VCAM-1-deficient embryos. At 8.5 days of gestation, the allantois failed to fuse to the chorion, resulting in abnormal placental development and embryonic death within 1-3 days. In addition, a role for VCAM-1 in early placental formation after chorioallantoic fusion was observed. In a minority of VCAM-1-deficient embryos, the allantois was able to fuse with the chorion, but the allantoic mesoderm was abnormally distributed over the chorionic surface. A small number of VCAM-1-deficient embryos survived, presumably by circumventing the placentation defects. They became viable and fertile adult mice with lack of VCAM-1 expression, normal organs, and an elevated number of circulating blood mononuclear leukocytes.

Allantois↗
PubMed1994

Use of a standardized heparin nomogram to achieve therapeutic anticoagulation after thrombolytic therapy in myocardial infarction. TIMI 4 investigators. Thrombolysis in Myocardial Infarction.

BACKGROUND: The recently completed Thrombolysis in Myocardial Infarction (TIMI) 4 Study compared three thrombolytic treatment regimens for acute myocardial infarction. The treatment arms included front-loaded recombinant tissue plasminogen activator (rtPA), anistreplase (APSAC), or both, in conjunction with an intravenous bolus of 5000 U of heparin, followed by 1000 U/h. To facilitate anticoagulation, a heparin nomogram was developed to maintain the therapeutic activated partial thromboplastin time at 1 1/2 to 2 times the control value. METHODS: A poll revealed that nine centers made use of the recommended heparin nomogram and six did not, adjusting the heparin dosage according to local practice. Anticoagulation parameters, major hemorrhagic events, and the frequency of heparin interruption were compared between centers that used and did not use the nomogram. RESULTS: Subtherapeutic activated partial thromboplastin time values were noted in 4%, 14%, 29%, 46%, 37%, and 34% of patients 8, 12, 24, 48, 72, and 96 hours, respectively, after heparin treatment was begun. Patients with subtherapeutic values at 24 hours were younger (mean +/- SD, 55.2 +/- 10.6 vs 59.6 +/- 10.6 years, P = .02) and weighed more (86.4 +/- 13.5 vs 78.9 +/- 15.7 kg, P = .007) than patients with therapeutic values. Centers that used the nomogram had significantly fewer subtherapeutic values at 48 and 96 hours. In addition, heparin therapy was interrupted less frequently at centers that used the nomogram (38.1% vs 68.7%, P < .001). Major spontaneous hemorrhage, reinfarction, and reocclusion rates were low and were about the same in the two groups. CONCLUSIONS: The use of a heparin nomogram provided improved anticoagulation in patients treated with thrombolytic therapy for myocardial infarction. Weight- and age-adjusted heparin dosing may provide further improvement in anticoagulation with heparin therapy. Our findings support the need for frequent monitoring of the activated partial thromboplastin time and for a standardized approach to adjusting the heparin dosage.

Aged↗
PubMed1994

Embryonal rhabdomyosarcoma of the floor of the mouth. A case report.

Rhabdomyosarcoma is a neoplasm composed of striated muscle. One of the most common types of soft tissue mesenchymal tumors in infants, children, and adolescents, rhabdomyosarcoma was considered an almost uniformly fatal cancer as recently as 30 years ago. Presently a multimodal approach consisting of surgery, radiation, and chemotherapy has significantly improved the outlook for the patient with rhabdomyosarcoma. This article presents a case of intraoral rhabdomyosarcoma that was initially poorly controlled because of a lack of patient compliance. After proper treatment, the cancer went into remission. The patient remained cancer-free for 7 years, albeit with significant morbidity. This case demonstrates the significantly improved prognosis achieved with multimodal therapy.

Adult↗
PubMed1994

Systemic phaeohyphomycosis caused by Xylohypha bantiana in a dog.

An 8-year-old, Maltese-cross bitch presented with chronic neck and back pain and an acute onset of circling, hyperaesthesia and constant crying. Clinical examination revealed temporal muscle atrophy, an abnormal hanging reflex, cervical rigidity and severe hepatomegaly. Ultrasonography of the liver showed several disseminated, poorly demarcated, hypoechoic areas which on fine needle aspirates, contained large numbers of pigmented fungal hyphae. Cerebrospinal fluid examination revealed fungal hyphae and numerous Ehrlichia canis morulae. A diagnosis of systemic phaeohyphomycosis secondary to ehrlichiosis was proposed. Treatment was unsuccessful and the dog was euthanased. At necropsy, multiple yellowish-green to black, necro-granulomatous foci were found throughout the liver parenchyma and similar foci were present in the spleen, renal cortices and adrenal glands. Irregular, multifocal, grey to black foci of malacia were present in both the grey and the white matter of the brain. On histopathological examination pigmented fungal hyphae were demonstrated in the liver, spleen, kidneys, portal lymph node and adrenals, as well as in the brain. Cultures of various organs yielded a fungal organism identified as Xylohypha bantiana.

Animals↗
PubMed1994

Measuring trait-depressive mood in adolescents with the depression adjective check lists.

The reliability and validity of the trait form of the Depression Adjective Check List (DACL) for Sets 1 and 2 were determined with adolescents in Grades 7 to 9 (Set 1) and Grades 8 to 12 (Set 2). Internal consistency, split-half, test-retest, and alternate form reliability were high, as was convergent and discriminant validity. Results of ANOVAs (Sex x Grade) and subsequent t tests for significant effects are reported. The performances of adolescents on the state and trait forms of Set 1 and Set 2 of the DACL were compared.

Adolescent↗
PubMed1994

Thalassaemia. Part 3 of 3. Counselling and community education.

In two previous articles, Simon Dyson, Verna Davis, and Raheya Rahman described the basic facts about thalassaemia and also considered the outcome of a preliminary survey establishing levels of awareness among community groups in one area. In this, the concluding article in the series, they look at the particular issues raised in thalassaemia counselling work and consider one approach to community education on the issue.

Genetic Counseling↗
PubMed1993

Thalassaemia: 1 of 3. Establishing basic awareness.

Thalassaemia has until recently received little attention and consequently is not widely understood by health professionals, write Simon Dyson, Verna Davis and Rafeya Rahman. In the first of three articles they describe the illness and its treatment and the potential role for health visitors in supporting children with the condition and their families. They conclude with a brief questionnaire to test thalassaemia-awareness levels.

Blood Transfusion↗
PubMed1993

Thalassaemia: 2 of 3. Current community knowledge.

In this second of three articles Simon Dyson, Verna Davis and Rafeya Rahman describe a study carried out in Manchester for the sickle-cell anaemia and thalassaemia centre to gauge the extent of community awareness about thalassaemia, the likely level of demand for further information and how that information might most usefully be given.

Health Knowledge, Attitudes, Practice↗
PubMed1991

Prognostic significance of the Karnofsky Performance Status score in patients with acute myocardial infarction: comparison with the left ventricular ejection fraction and the exercise treadmill test performance. The MILIS Study Group.

The prognostic significance of functional status has not been previously studied in the setting of acute myocardial infarction. We assessed the Karnofsky Performance Status (KPS) score, a simple functional status scale that is commonly used to categorize physical ability, in 849 patients with acute myocardial infarction who were enrolled in the Multicenter Investigation of the Limitation of Infarct Size (MILIS) study. We then compared the KPS score with other predictors of prognosis in these patients. In patients who presented with acute myocardial infarction, a lower KPS score (less than 8 on a scale of 1 to 10) 3 weeks before the index infarction was associated with a higher incidence of congestive heart failure, in-hospital cardiac arrest, and mortality during hospitalization, as compared with patients with KPS scores greater than or equal to 8 (each p less than 0.001). Cumulative 1-year and 4-year mortality rates were significantly higher in patients with KPS scores less than 8, as compared with patients with KPS scores greater than or equal to 8 (42.5% vs. 12.6% at 1 year and 61.6% vs 25.1% at 4 years, respectively; both p less than 0.001). The left ventricular ejection fraction on admission was significantly lower in patients with KPS scores less than 8, as compared with those with KPS scores greater than or equal to 8 (p less than 0.019). The cumulative mortality rate was equally well predicted by low KPS score and by left ventricular ejection fraction (both p less than 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)

Disability Evaluation↗