Translumbar placement of inferior vena caval catheters: a solution for challenging hemodialysis access

Access to the central venous circulation for hemodialysis has traditionally been achieved via the subclavian or jugular venous routes. With ongoing improvements in medical management, many hemodialysis recipients develop exhaustion of these routes and require alternative means of central venous access. Inferior vena caval (IVC) catheters have been placed with a percutaneous translumbar approach to allow central venous access for chemotherapy, harvesting of stem cells, and total parenteral nutrition. Translumbar placement of IVC catheters has become accepted by some as a useful and reliable alternative in patients who require long-term hemodialysis but have exhausted traditional access sites. IVC catheters have been placed in patients with IVC filters, and IVC filters have been placed in patients with IVC catheters. Complications include those associated with central venous catheters, for example, sepsis, fibrin sheaths, and thrombosis. A complication specific to placement of IVC hemodialysis catheters is migration of the catheter into the subcutaneous soft tissues, retroperitoneum, or iliac veins. Translumbar placement of IVC catheters is performed only in patients considered to have few or no other medical options and is not intended as a primary means of central venous access.     

Tea plant root extract (TRE) as an antineoplastic agent

The antitumour effect of tea plant root extract (TRE) has been evaluated against Ehrlich ascites carcinoma (EAC) in Balb-C mice. Significant increases of survival times of the TRE-treated, tumour-bearing mice have been confirmed repeatedly with respect to the control group. TRE inhibited the tumour cell growth and reversed the changes of haematological parameters consequent to tumour inoculation.     

Genomic characterization of the coding region of the human type II 5''-deiodinase gene

The conserved residue Asp477 in yeast transketolase is located in the substrate channel of the enzyme and forms a hydrogen bond with the C2-hydroxyl group of the acceptor substrate. The significance of this interaction for the recognition of the preferred acceptor substrates, D-alpha-hydroxyaldehydes was investigated by site-directed mutagenesis. In the wild-type enzyme the kcat/KM values are by three to four orders of magnitude lower for 2-deoxyaldoses or substrates with L-configuration at the C2-atom. In the Asp477 Ala mutant, the kcat/KM values for D-alpha-hydroxyaldehydes are decreased by a thousandfold, while the kcat/KM values for substrates with L-configuration or 2-deoxyaldoses are similar to wild-type enzyme. These results indicate that Asp477 is involved in determining the enantioselectivity of transketolase.     

Metabolism of bromodichloroacetate in B6C3F1 mice

Trichloroacetate (TCA), dichloroacetate (DCA), and bromodichloroacetate (BDCA) are byproducts of the chlorination of drinking water. TCA acts primarily as a peroxisome proliferator, but DCA produces tumors at doses less than required for peroxisome proliferation. BDCA does not induce peroxisome proliferation even at high doses. This study attempts to determine whether differences in the metabolism of the trihaloacetates (THAs) may contribute to their differing toxicological properties. Studies were performed in male B6C3F1 mice given [14C1,2]TCA, [14C1]BDCA, and [14C1,2]DCA by gavage. The replacement of a Cl by a Br greatly enhances THA metabolism. Much less radiolabel from BDCA is retained in the carcass after 24 hr than from TCA. Radiolabel from BDCA is largely found in the urine, with oxalate being the major metabolite. TCA is largely eliminated unchanged in the urine. There are dose-related changes in the rate of CO2 production from BDCA. The initial rate of CO2 production is reduced from 4.1 +/- 0.3 hr-1 at 5 and 20 mg/kg to 2.7 +/- 0.6 hr-1 at 100 mg/kg, but the net conversion to CO2 in 24 hr is greater at the highest dose. As would be predicted, substitution Br for Cl on TCA greatly increased its metabolism.     

A mesoscopic ballistic electron mixer with efficient frequencyconversion at radio frequency

The voltage-current characteristic of a four-terminal mesoscopic cross is grossly nonlinear, exhibiting two clear regions of negative differential resistance (NDR). This behavior is potentially useful in millimeter wave detectors since these small devices have very low parasitic capacitance and great sensitivity. The device exploits a planar GaAs technology which lends itself to integrated systems. We have exploited one of the NDR regions (at a current of only 1.9 μA) to carry out frequency conversion. At low frequency we observed efficient frequency doubling, with the second harmonic exceeding the fundamental by up to 10 dB at the output. We have also operated the device at radio frequency (5 MHz) and demonstrated both asynchronous and heterodyne amplitude demodulation. The effect of DC current bias was examined and it was shown that biasing the device close to the NDR gave the optimum frequency conversion. A conversion loss in the heterodyne mixer circuit of 3 dB was achieved     

Periodontal surgery of vertical bony defects with or without synthetic bioabsorbable barriers. 12-month results

The aim of the present study was to clinically and radiographically compare guided tissue regeneration (GTR) therapy with bioabsorbable polyglactin 910 barriers and conventional periodontal surgery in intrabony defects. In 26 patients with advanced periodontitis, 29 teeth exhibiting interproximal intrabony defects were treated; 15 by conventional periodontal surgery (control) and 14 by GTR (test). Before and 12 months after surgery, clinical parameters were assessed and standardized radiographs were taken. On the radiographs the distances from the cemento-enamel junction (CEJ) to the alveolar crest (AC), and the CEJ to the most apical extension of the bony defect (BD) were measured using a computer-assisted analyzing device (LMSRT). Twelve months after surgery, 24 patients with 27 lesions were available for examination. For both methods statistically significant (P < 0.001) probing depth (PD) reduction (mean +/- standard deviation) of -4.49 +/- 1.94 mm (n = 13, test) and -3.22 +/- 1.48 mm (n = 14, control), as well as clinical attachment gain (CAL-V) of 3.41 +/- 1.59 mm (test) and 2.07 +/- 1.10 mm (control), was observed. Radiographic changes of the distance CEJ to AC of -0.95 +/- 1.72 mm (n = 9, test), and -0.98 +/- 1.53 mm (n = 11, control) were not significant. A significant bony fill (distance CEJ-BD) of 1.05 +/- 1.22 mm was observed for the test group (P < 0.01); the 0.68 +/- 2.04 mm bony gain for the control group was not statistically significant. The PD reduction (P < 0.05) and attachment gain (P < 0.01) in the test group was statistically significantly more favorable than in the control group. Twelve months after surgery, statistically more favorable PD reduction and attachment gain was observed using polyglactin 910 barriers than compared to conventional flap surgery. Hence, the use of bioabsorbable barriers for therapy of intrabony defects may be recommended.