Stimulation of adenylate cyclase activity in cultured endothelial cells subjected to cyclic stretch

While vascular endothelial cells are repeatedly stretched by the pulsatile nature of cardiac output, in vitro models traditionally used to study vascular biology involve static culture techniques. We have recently shown that pulsatile stretching of endothelial cells in culture will increase their rates of proliferation and regulate their secretion of macromolecules. The aim of this study was to determine whether membrane adenylate cyclase is involved in intracellular signalling during pulsatile stress. Bovine aortic endothelial cells were seeded on flexible-bottomed culture wells (3 x 10(5) cells/25 mm well) and allowed to attach for 48 hours. The culture wells were placed in a vacuum-operated stress providing instrument and subjected to 0.5 s of 24% strain, 0.5 s relaxation (60 cycles/min) for 0, 1, 3, 5, 7, 10 and 15 minutes (N = 24 wells/time point). Cells were homogenized and a crude membrane preparation (27,000 x g) was assayed for adenylate cyclase under basal and forskolin (100 microM) stimulated conditions. The results indicate that there is a time-dependent increase in both basal and stimulated adenylate cyclase with cyclic deformation and suggest that there may be a "stretch receptor" coupled to adenylate cyclase which can modulate endothelial cell function with hemodynamic changes.     

Ventilation parameters and arterial blood gases as a prediction of hypoplasia in congenital diaphragmatic hernia

Attempts to predict the degree of pulmonary hypoplasia associated with congenital diaphragmatic hernia have been made by evaluating the ventilation parameters and the arterial blood gasses of these patients. A CO2 index as a predictor of outcome, which correlates the PaCO2 with the ventilation index, was recently proposed. However, in this study the postductal PaO2 was a better predictor of survival. And the so-called "honeymoon period" was a better indicator of the efficacy of extracorporeal membrane oxygenation (ECMO) than the CO2 index. Nineteen patients were evaluated; 11 were treated with ECMO, and eight were not considered suitable for ECMO.     

An evaluation of two methods for chronic central venous access device placement

BACKGROUND: Chronic venous access devices (CVADs), placed for phlebotomy and the administration of medications and nutrition, require fluoroscopy to confirm correct catheter position. Long-term central venous catheters placed using an electromagnetic catheter locating system (EMCLS) could result in decreased radiation exposure and decreased cost without compromising accuracy of position. METHODS: Charts of patients who underwent placement of CVADs at University of New Mexico (UNM) Hospital or UNM Cancer Center were reviewed. Inclusion criteria included age >20 years and placement of a central CVAD utilizing fluoroscopy (group 1) or the EMCLS (group 2). Radiation exposure, complications, cost, and accuracy of placement were determined for each technique. RESULTS: Between June 1996 and June 1998, 196 patients underwent placement of CVADs. Complete data sets were available for 46 patients in each group. There were no statistically significant differences in age, gender, complications, or operating room times (P = 0.26). Fluoroscopy and EMCLS were equally accurate for the correct placement of the tip of the line (P = 0.12). Mean patient radiation exposure was EMCLS, 30 mRem, and fluoroscopy, 771 mRem. EMCLS significantly decreased cost (P = 0.025) when compared with fluoroscopic assisted catheter placement. CONCLUSIONS: The use of EMCLS for CVAD placement reduces radiation exposure and cost without compromising the accuracy of placement when compared with standard fluoroscopic-assisted placement.     

Measurement of lumbar spine kinematics in incline treadmill walking

A study was undertaken to analyse and compare the pelvic (S1) and the trunk (T12) oscillations during level and uphill walking and to provide kinematic baseline data of the lumbar region in incline walking for future comparisons with pathological gait patterns. An ultrasonic movement analysis device (Zebris(R) CMS 50) was used to obtain three-dimensional kinematic data for the pelvis and thorax. Data from treadmill walking at 0 and 10% incline of 22 adults were used for within subject analysis. Crosscorrelation values ranged from r=0.76 to 0.98 (P<0.001) demonstrating a strong degree of agreement between the temporal patterns of angular displacement of the trunk and pelvis in the sagittal, transverse and frontal plane in incline compared to level ambulation. However, Student's t-tests revealed significantly (P<0.01) higher amplitudes for thorax displacements in the frontal and transverse plane in uphill walking. No significant differences were detected for amplitude parameters of the pelvis. It could be stated that the phasic patterns in level walking are not different from that obtained for incline walking. It is concluded that incline ambulation exerts the major influences in the thoracic region by increasing amplitudes of axial rotations.     

Less invasive surgical treatment of renal cell carcinomas extending into the right heart and pulmonary arteries: surgery for renal cell carcinoma

BACKGROUND: Radical resection using deep hypothermic circulatory arrest improves the survival of patients with transvenous intracardiac tumor extension of renal cell carcinomas. A less invasive surgical approach avoiding deep hypothermia, circulatory arrest, and cross-clamping of the aorta is presented. METHODS: Between 1987 and 1999, 12 patients (mean age 57+/-8 years) underwent resection of a renal cell carcinoma extending into the right atrium, right ventricle, or pulmonary arteries. After median sterno-laparotomy, normothermic cardiopulmonary bypass is used cannulating the ascending aorta, superior caval vein, and inferior caval vein below the renal veins. The tumor and the corresponding kidney are radically excised, including the renal vein. Tumor fragments from the inferior caval vein, the right heart, and pulmonary arteries are removed either on the fibrillating or beating heart. RESULTS: Operative mortality was 0%. Mean cardiopulmonary bypass time was 53+/-27 minutes (median 36; range 32-110 minutes). Mean blood loss per patient was 1200 mL. Mean duration of postoperative mechanical ventilation was 36+/-12 hours (median 36; range 30-77 hours), mean intensive care stay 5.5+/-5 days (median 3; range 1-48 days), and mean duration of hospitalization 22+/-12 days (median 21; range 10-58 days). All patients were discharged home. Patients with multiple tumor manifestations outside the cardiovascular systems died within 9 months after the operation. CONCLUSIONS: The use of normothermic cardiopulmonary bypass is a less invasive method for radical resection of renal cell carcinoma with intracardiac tumor extension. Radical resection does not improve survival in patients with multiple distant metastases.     

p53-expression and chromosome 17-copy number in colorectal adenomas

To get better insight into the role of numerical chromosome 17-aberrations and functional loss of the tumor suppressor gene TP53 during the early steps of colorectal carcinogenesis we analyzed paraffin-embedded tumor tissue from 58 colorectal adenomas with different histological features for p53-expression by immunohistology (IH; moAb DO1), #17-copy number by interphase-cytogenetics [nonradioactive in situ-hybridization (NISH) with a centromer-specific DNA-probe (D17Z1)], and DNA-ploidy by flow cytometry (FCM) with special emphasis on histopathological correlation. Seven adenomas (12%) showed nuclear p53-immunoreactivity. p53-expression was correlated with villous/tubulo-villous growth pattern (p=0.005) and grade of atypia (p=0.003) or dysplasia (p=0.0018). #17-aneusomy was present in 31% of the cases (29% deletions, 2% gains). In the FCM-analysis, 33% of the adenomas were DNA-non-diploid. p53-immunoreactivity correlated statistically significantly with FCM-non-diploidy (p=0.004) suggesting a role for the TP53-gene in the aneuploidization process. #17-deletions were associated to p53-immunoreactivity (p=0.046) but no correlation was found between FCM-ploidy and #17-copy number. As for loss of a tumor suppressor gene both alleles have to be affected, our data suggest a multistep process of TP53-inactivation. Whether the subgroup of adenomas with p53-expression might progress faster into invasive carcinoma than p53-negative cases remains to be tested.     

Beta-oxidation of 1-[14C]-17-[131I]-iodoheptadecanoic acid following intracoronary injection in humans results in similar release of both tracers

Radioiodine labelled 17-iodo-heptadecanoic acid (IHA) is used for non-invasive study of myocardial metabolism in coronary heart disease and cardiomyopathy. Yet in the interpretation of in vivo myocardial tracer kinetics, it is controversial whether the intracellular degradation of IHA or the removal of iodide across cellular membranes is the rate-limiting step in iodide release from the myocardium. In five patients undergoing coronary sinus catheterization, a mixture of about 40 kBq of [¹²³I] NaI was injected into the left coronary artery. During the following 15-min period, frequent blood samples were taken from the aorta and the coronary sinus. In the aqueous phase of the venous blood, ¹⁴CO₂ and inorganic ¹³¹I appeared nearly in parallel, with a peak time of 4–5 min. Moreover, as shown by the AV difference, there was no significant back diffusion of IHA and no significant non-specific deiodination detectable over the period of observation. There was myocardial retention of inorganic iodide (¹²³I) injected into the left coronary artery. The data strongly support the premise that lipid turnover through -oxidation is the rate-limiting step in the externally measured release of iodide after IHA injection, provided that recirculating inorganic radioactive iodide is corrected for. In addition, 15 volunteers were studied using [¹¹C]palmitic acid and [¹²³I]IHA using PET and dynamic planar camera scintigraphy with iodide correction. There was no significant difference between the mean values of the elimination half-times, and also no significant correlation between half-times of both fatty acids for single individuals.     

POSSIBLE INVOLVEMENT OF INOSITOL-LIPID METABOLISM IN MALIGNANT HYPERTHERMIA

-Adrenoceptor stimulation may induce malignant hyperthermia(MH) in vivo. Consequently, we have investigated the effectsof the -adrenoceptor agonist phenylephrine and, for comparison,the effects of the ß-adrenoceptor agonist isoproterenolon inositol-lipid metabolism of malignant hyperthermia susceptible(MHS) and healthy control (MHN) swine. The experiments wereperformed on electrically stimulated (frequency 0.2 Hz) trabeculaeisolated from the right ventricles of the hearts of MHS andMHN animals. After labelling with [³H] inositol for 6 h, differentinositol phosphates were measured by high pressure liquid chromatography,including inositol 1 - phosphate, inositol 1,4-bisphosphate,inositol 1,3,4-trisphosphate, inositol 1,4,5-trisphosphate (1,4,5-IP₃)and inositol 1,3,4,5 - tetrakisphosphate. After stimulationwith isoproterenol, the inositol phosphate content did not increaseor vary between muscle from MHS and MHN animals. In contrast,all inositol phosphates increased after stimulation with phenylephrinein both muscle types, the effects being greater in MHS thanin MHN, especially as regards 1,4,5-IP₃ content. As 1,4,5-IP₃,a presumed second messenger, has been shown to mobilize intracellularcalcium, it is concluded that an enhanced -adrenergic responseis involved in the development of MH. ^*Address for correspondence: Abteilung für Anästhesiologie,Universitäts-Krankenhaus Eppendorf, Martinistrasse52, D-2000Hamburg 20, Germany. Presented in part at the 1989 Meeting of the European Academyof Anaesthesiology in Bonn.