Search PubMed⌕ Search

Biomedical subjects

P Wehner

Publications and source records attributed to P Wehner.

8 recordsLinked to original sources
PubMed2006

Aging alters mechanical and contractile properties of the Fisher 344/Nnia X Norway/Binia rat aorta.

Vascular mechanical and contractile properties were compared in adult (6 months old) and very-aged (36 months old) Fischer 344/NNiaHSd X Brown Norway/BiNia (F344/NXBN) rats. Our previous work has indicated that aging is associated with aortic medial thickening. This morphological alteration was accompanied by a leftward shift in the aortic stress/strain curve indicating increased vessel stiffness in very-aged animals. Disruption of the endothelium as well as pretreatment of tissues with the nitric oxide (NO) donor sodium nitroprusside eliminated differences, suggesting a link between deficient endothelial NO release and reduced compliance in very-aged aortae. In addition, the Rho kinase inhibitor Y-27632 increased vessel compliance in both adult and very-aged tissues suggesting that the Rho cascade contributed to the stress/strain relationship. Maximal force developed in response to high potassium (K(+)) was reduced by approximately 70% in intact and endothelium-denuded aortae from very-aged rats. In contrast to contractile force development, calcium-dependent stress relaxation was increased in very-aged aorta. Finally, gel electrophoresis indicated a significantly higher tissue content of myosin heavy chain and a higher ratio of SM1/SM2 isoforms with aging. The results suggest multiple molecular changes with aging, which may be expected to alter vascular tissue function.

Aging↗
PubMed2003

Effect of fasting on vascular contractility in lean and obese Zucker rats.

We compared the effects of fasting (36 h) on blood pressure and aortic contractile responsiveness in lean and obese Zucker rats. Fasting of lean animals resulted in a significant loss in body weight (-9.1 +/- 0.1%) and reduction in systolic blood pressure (-11.4 +/- 1.9 mmHg). Fasting plasma triacylglycerols (-76%) and beta-hydroxybutryic acid (beta-HBA) (+ 218%) were significantly decreased and increased, respectively. The fasting plasma concentrations of insulin (-72%) were significantly decreased, whereas glucose and epinephrine (Epi) were not changed in lean rats. The fasting of obese rats also resulted in weight loss (-5.6 +/- 1.3%) but did not cause a significant reduction of blood pressure. The plasma total cholesterol (+18%) was increased, triacylglycerols (-42%) were decreased and beta-HBA levels were unchanged in fasted obese rats. Similar to lean animals, the insulin levels of fasted obese rats were significantly decreased (-85%), whereas glucose and Epi concentrations were not significantly changed. Fasting of lean animals had no effect on the maximal contractile response of aortae to high K(+) and phorbol 12, 13 dibutyrate (PDBu) but significantly reduced the response to norepinephrine (NE) (% reference: fed, 61.1 +/- 11.0; fasted, 45.6 +/- 4.5). In addition, the concentration for half-maximal response (ED(50)) to NE was increased in fasted lean rats (fed, 1.8+/-0.2 x 10(-8)M; fasted, 3.0+/-0.3 x 10(-8)M). By comparison, fasting of obese rats had no significant effect on the contractile response to K(+), NE, or PDBu. The results show that short-term food withdrawal induces significant changes in vascular contractile properties of lean but not obese rats. Because fasting-induced changes were variable depending on the agonist, the results further suggest that the mechanism did not involve a general loss or enhancement in functional status.

3-Hydroxybutyric Acid↗
PubMed2001

A novel lentivirus vector derived from apathogenic simian immunodeficiency virus.

The improvement of gene transfer efficiency in growth-arrested cells using human immunodeficiency virus type 1 (HIV-1)-derived vectors led to the development of vectors derived from other members of the lentivirus family. Here we report the generation of a lentiviral vector derived from the apathogenic molecular virus clone SIVagm3mc of the simian immunodeficiency virus from African green monkeys (Cercocebus pygerythrus). Upon pseudotyping with the G-protein of vesicular stomatitis virus (VSV-G), the SIVagm-derived vector was shown to transduce proliferating and growth-arrested mammalian cell lines, including human cells. After in vivo inoculation into the striatum of the adult rat brain, the vector was shown to transduce terminally differentiated neurons and oligodendrocytes as well as quiescent and reactive astrocytes. Moreover, SIVagm transfer vector mRNA was efficiently packaged by HIV-1 vector particles. Homologous [SIV(SIV)] vectors generated by using the SIVagm-derived envelope glycoproteins allowed selective gene transfer into human CD4(+)/CCR5(+) cells. Thus, the SIVagm3mc-derived vector is a useful alternative to HIV-1-derived lentiviral vectors in somatic gene therapy.

Animals↗
PubMed1994

Physician-induced demand for childbirths.

A controversial technique for testing the hypothesis that physicians induce demand involves two stage least squares (TSLS) regression analysis of cross-section data on physician supply and utilization. This paper tests the power of TSLS by applying it where there is at most only a trivial amount of demand inducement--the demand for childbirths. We find 'evidence' of inducement of childbirths, calling into question the validity of the TSLS approach. This unlikely finding may be traced to at least two factors: The first stage regression is not identified and the second stage regression does not adequately address border crossing.

Birth Rate↗
PubMedDate not supplied

Arrhythmogenic right ventricular dysplasia: an uncommon cause of syncope in a young male.

Arrhythmogenic right ventricular dysplasia (ARVD) is a relatively rare disease first described in 1977. It is characterized by replacement of the right ventricle (RV) by fat or fibrous tissue. Patients often present with symptomatic ventricular tachycardia (VT) and the risk of sudden death is approximately 2.5% per year. Physical exam is often unremarkable. To date, the best diagnostic test is the MRI, however, electrocardiographic and echocardiographic data are useful. Treatment can be with beta blockers if a medical approach is desired. Multiple surgical options are available. No long-term studies are available to guide therapy; thus each case should be dealt with on its merits. This article describes the case of a 41-year-old male who had been asymptomatic until he presented with syncope. An extensive work up was undertaken and ARVD was diagnosed by MRI.

Adult↗
PubMedDate not supplied

Syndrome myxoma presenting as a pulmonary embolism: a case report.

Although the incidence of primary cardiac tumors is approximately 0.28%, they are encountered in every age group and their clinical presentation usually resembles that of other cardiac or systemic diseases. The clinical symptoms of primary cardiac tumors are usually few until they are at an advanced critical stage making early diagnosis and treatment problematic. However, there is a subgroup of patients who may present with extracardiac systemic, endocrinologic or cutaneous manifestations and familiar inheritance allowing for early detection. This article describes the diagnosis and treatment of a young female who presented with an acute thromboembolic complication of an intracardiac myxoma.

Adult↗
PubMedDate not supplied

Directional coronary atherectomy in acute myocardial infarction.

Catheter-based intervention with directional coronary atherectomy (DCA) involving the surgical removal of obstructive plaque has been extensively studied in patients exhibiting stable and unstable angina. However, since no studies to date have evaluated the effectiveness of stand alone DCA as a primary treatment in the acute myocardial infarction (MI) setting, we conducted a five-year retrospective study of the early clinical and in-hospital outcomes of patients who underwent DCA within the 72-hour interval following acute MI. Our study included data obtained from a total of 30 acute MI patients treated between 1993 and 1998. Twenty-six of these patients (86%) met the criteria for angiographic success, while 11 (36%) showed less than 50% residual stenosis without the need for supplemental percutaneous transluminal coronary angioplasty (PTCA) or additional treatment for other major complications. Four (13%) of the patients exhibited negative outcomes including post-procedural MI, emergency coronary artery bypass grafting, abrupt vessel closure, hemorrhage necessitating vessel repair and transfusion, and death. Although stand alone DCA is not presently a common treatment, our results suggest it to be an effective and relatively safe procedure for acute MI. However, further studies involving a larger number of patients and a longer follow-up evaluation are needed for comparison of the relative effectiveness of this procedure with other treatments of acute MI.

Adult↗