Biomedical subjects

Thomas Walther

Publications and source records attributed to Thomas Walther.

113 records · Page 7Linked to original sources

PubMed2002

Multiple interactions between the renin-angiotensin and the kallikrein-kinin systems: role of ACE inhibition and AT1 receptor blockade.

The investigation of therapeutic actions of angiotensin type 1 (AT1) receptor antagonists and ACE inhibitors (ACEI) demonstrated complex interactions between the renin-angiotensin system (RAS) and the kallikrein-kinin system (KKS) in several experimental and clinical studies. They are evidenced by the fact that (1) ACE efficiently catabolizes kinins; (2) angiotensin-derivatives such as ANG-(1-7) exert kininlike effects; and (3) kallikrein probably serves as a prorenin-activating enzyme. (4) Several authors have demonstrated experimentally that the protective effects of ACEI are at least partly mediated by a direct potentiation of kinin receptor response on BK stimulation. (5) Furthermore, studies on AT1 antagonists, which do not directly influence kinin degradation, and studies on angiotensin-receptor transgenic mice have revealed additional interactions between the RAS and the KKS. There is mounting evidence that an autocrine cascade including kinins, nitric oxide, prostaglandins, and cyclic GMP is involved in at least some of the angiotensin type 2 receptor effects. This review discusses multiple possibilities of cross-talks between the RAS and KKS in vascular and cardiac physiology and pathology after ACE inhibition and AT1 receptor blockade.

Angiotensin Receptor Antagonists↗

PubMed2002

Cell type-specific expression of the Mas proto-oncogene in testis.

The Mas proto-oncogene encodes a G-protein-coupled receptor with the common seven transmembrane domains and may be involved in the actions of angiotensins. Because Mas is highly expressed in testis, we investigated the cell type-specificity and the onset of expression of the gene in this organ. Using an RNase protection assay, it could be shown that neither whole testes nor cultured Sertoli and Leydig cells of 12-day-old mice express Mas mRNA. Mas expression is first detected in 18-day-old mice and thereafter increases continuously until 6 months of age. By in situ hybridization, the expression could be localized to Leydig cells and Sertoli cells, the signals being much more pronounced in the former. A weak signal was detected in primary spermatocytes. The strong ontogenetically controlled and cell type-specific expression of this membrane-bound receptor in testis implicates a role for the Mas proto-oncogene in testis maturation and function.

Animals↗

PubMedDate not supplied

Temporary extracorporeal membrane oxygenation in patients with refractory postoperative cardiogenic shock--a single center experience.

BACKGROUND: Approximately 1% of patients require temporary circulatory support due to refractory cardiogenic shock following cardiac surgery. Such patients are at very high risk for subsequent morbidity and mortality. We evaluated the results of temporary extracorporeal membrane oxygenation (ECMO) support in patients with postcardiotomy cardiogenic shock. METHODS: From November 1997 to February 2000, 7900 patients underwent cardiac surgery in our institution. Ninety-five patients (1.2%) (CABG, n = 63; AVR, n = 16; CABG and AVR, n = 8; other procedures, n = 8) required temporary postoperative ECMO support. ECMO implantation was performed via the femoral vessels or via the right atrium and ascending aorta. Intraaortic balloon counterpulsation was employed in all patients. RESULTS: Mean duration of ECMO support was 2.8 +/- 2.1 days. Forty-five patients (47%) were successfully weaned from ECMO. Of these, 28 patients were discharged from hospital 35.8 +/- 20.8 days post-ECMO support. Overall hospital mortality for all ECMO patients was considerable at 71%. Mortality rate in the combined CABG and AVR group was 100% (P < 0.05 versus the other surgical groups). ECMO support was complicated by renal failure in 64% of patients, bleeding requiring mediastinal reexploration in 62%, ischemia of the lower limbs in 16%, cerebral edema in 6%, and cerebral hemorrhage in 3%. CONCLUSIONS: ECMO is a suitable technique for short-term treatment of refractory postoperative low cardiac output. Mortality rates are comparable to other cardiac assist devices, with approximately 30% of patients able to be discharged from hospital.

Aged↗

PubMedDate not supplied

Swan-Ganz catheter-induced severe complications in cardiac surgery: right ventricular perforation, knotting, and rupture of a pulmonary artery.

BACKGROUND: The role of Swan-Ganz catheterization for cardiac surgery and perioperative management has recently been scrutinized. METHODS: Prospective observational study for serious complications related to Swan-Ganz catheterization. 7150 patients undergoing cardiac operations at a major European heart center and academic setting. 3730 Swan-Ganz catheter placements for cardiac surgery (7.5 French Swan-Ganz Catheter Baxter, heparin coated). RESULTS: We observed four serious complications related to Swan-Ganz catheterization and placement (0.1%): A right ventricular free wall perforation occurred, one trouble with knotting, and two pulmonary artery ruptures. The right ventricular perforation was controlled with a suture, the knot was tightened, and the catheter withdrawn through insertion. The first case of pulmonary artery rupture was treated conservatively. All of these patients survived. The other pulmonary artery rupture occurred during coronary artery bypass grafting. Emergency lobectomy was performed. This patient died due to bleeding during the early postoperative course. CONCLUSION: The incidence of serious Swan-Ganz catheter complications in our patient population is comparable to the incidence reported in the literature. Based on these results the use of Swan-Ganz catheters in cardiac surgery is still justified since the rate of associated serious complications is extremely low. Despite the rare occurrence of serious complications and the infrequent fatal outcomes, the benefit of its use in selected cases of cardiac surgery overweight its associated complications.

Aged, 80 and over↗

PubMedDate not supplied

Expression of C-type natriuretic peptide in human placenta and myometrium in normal pregnancies and pregnancies complicated by intrauterine growth retardation. Preliminary results.

OBJECTIVE: C-type natriuretic peptide (CNP) is a vasoactive hormone and the endothelial component of the natriuretic peptide system. At present, nothing is known about CNP expression in human reproductive tissue. Since CNP shows antimitogenic and vasodilatative properties, it was the aim of the study to investigate whether CNP expression is altered in placenta and myometrium from pregnancies complicated by intrauterine growth retardation. METHODS: CNP expression was examined by RNase protection assay in human placenta and myometrium from six normal term pregnancies, six pregnancies with preterm delivery and six pregnancies complicated by intrauterine growth retardation (IUGR). RESULTS: In placenta and myometrium, CNP expression levels did not differ between term and preterm pregnancies (40 vs. 28 weeks of gestation). In pregnancies with IUGR (34 weeks of gestation) placental CNP expression was significantly decreased (100.00 +/- 18.6 vs. 67.09 +/- 8.7; p < 0.05). In the myometrium from IUGR pregnancies CNP expression was significantly increased to 191.48 +/- 42.5 (vs. 100.00 +/- 15.4; p < 0.05). CONCLUSIONS: CNP is expressed in human placenta and myometrium with no dependency on gestational age in the third trimester. Pregnancies with IUGR show an opposite regulation of CNP in placenta and myometrium, which indicates an organ-specific function of the peptide in human reproductive tissue.

Female↗