Aortic perforation during lumbar laminectomy

A method to determine the optimal replacement time for dye affinity adsorbents used in protein purification processes that are subjected to severe regeneration conditions has been developed. To demonstrate the utility of the method, an experimental fixed-bed decay model was employed to determine the optimum number of cycles for the adsorbent replacement. This number is a function of the column regeneration frequency and of the capital and operation costs. The implications of the results on the design and operation of dye-ligand chromatographic processes are discussed.     

Direct comparison of three methods for the determination of radon in well water

Radon concentrations obtained using a bubbler device developed to collect and bubble water samples in the laboratory and field were compared with results from conventional liquid scintillation counting. Measurements from standard solutions with a wide concentration range showed excellent agreement between liquid scintillation and results obtained using the bubbler device in conjunction with alpha-scintillation cells. Measurements of waterborne radon concentrations in 110 community and private wells in New York State ranged from 1 to 4,100 Bq L-1, with arithmetic and geometric means of 200 and 30 Bq L-1, respectively. Excellent agreement between the analytical techniques was obtained for each field site.     

Effects of clorazepate, diazepam, and oxazepam on a laboratory measurement of aggression in men

The liver S9 head space vial equilibration technique is an in vitro alternative that holds promises for a satisfactory in vivo extrapolation of liver metabolism of volatile organic chemicals. The aim of this study was to investigate the suitability of this methodology for the extrapolation of in vitro metabolic data from rodent to man by allometry with the two highly metabolized organic solvents toluene and n-hexane as model substances. The calculated hepatic clearance of toluene in man from rodent liver S9 in this study was equal to the reported total body clearance of toluene in man, suggesting insignificant extrahepatic clearance of toluene in humans. The calculated hepatic clearance of n-hexane was less than the reported values of total body clearance of n-hexane in man, indicating an about 80% extrahepatic clearance of n-hexane in humans. Both results are in line with our present knowledge of the metabolism of the two organic solvents in man. Allometric scaling from rodent liver S9 head space incubations to in vivo metabolism of toluene and n-hexane in man thus seems promising and could be a method of choice for scaling of organic solvent metabolism in general.     

Sex differences and androgen-dependent regulation of aromatase (CYP19) mRNA expression in the developing and adult rat brain

Sex differences, androgen dependence and asymmetries of aromatase activity have been reported during ontogeny of the rat. It remains to be elucidated, however, whether the changes in aromatase activity are reflected by similar changes in specific mRNA levels. In addition, very little is known regarding mechanism(s) underlying such differential regulation of aromatase expression. To address these questions, we have employed the in situ hybridization (ISH) technique to examine specific mRNA levels in the brain of both male and female rats at selected stages of development. In prenatal stages of development, at gestational day (GD) 18 and 20, aromatase mRNA was detected in several hypothalamic and limbic brain regions. Semiquantitative analysis of aromatase mRNA did not reveal statistically significant sex differences in any of these regions (except in one experiment at GD20, when a sex difference was found in the medial preoptic nucleus). In contrast, clear sex differences were determined at postnatal day (PN) 2; male animals contained significantly more aromatase mRNA in the bed nucleus of the stria terminalis (BST) and the sexually dimorphic nucleus of the preoptic area (SDN) compared to female rats. Four days later in development, at PN6, sex differences of aromatase mRNA signals were observed in the BST, but were no longer detectable in the SDN. At PN15 and in adult animals, no sex differences could be determined. The effect of flutamide treatment (50 mg/kg/day) was investigated in GD20 fetuses as well as in adult rats. No statistically significant changes in aromatase mRNA expression were found in either case. In summary, our results suggest that differential regulation of aromatase mRNA expression during the critical period of sexual differentiation might, in part, account for the establishment of some of the many sexually dimorphic parameters of the rat brain. The role of androgens in the regulation of the sex-specific and developmental expression of aromatase mRNA in the rat brain remains to be clarified.     

Single-agent paclitaxel in patients with previously untreated stage IV epithelial ovarian cancer. London Gynaecological Oncology and North Thames Gynaecological Oncology Groups

OBJECTIVES: Prostate-specific antigen (PSA) is a widely used serum marker for human prostate cancer (PCa). The majority of PSA in serum is present as a complex with alpha-1-antichymotrypsin (ACT). In recent years, the ratio of free (uncomplexed) to total PSA has shown improved discrimination of PCa from benign prostatic hyperplasia. This study examines the nature of the free PSA from detected in PCa serum and shows that some of the uncomplexed PSA is an inactive precursor of PSA (pPSA). METHODS: Western blot analysis was used to detect clipped, fragment forms of PSA in sera and seminal fluid. Hydrophobic interaction chromatography-high performance liquid chromatography (HIC-HPLC) was used to identify forms of PSA present in the free PSA population. Pooled sera was passed over a PSA immunoaffinity column, and the eluted PSA components were further resolved by HIC-HPLC. RESULTS: Western blot analysis of whole sera showed complexed PSA and the intact, approximately 34 kilodalton free PSA. Only negligible levels of clipped or degraded forms of PSA, as found in seminal fluid, were detected. Column fractions measured for uncomplexed PSA using the Tandem-MP free PSA assay showed that about 25% of the free PSA eluted as pPSA beginning at the [-4]amino acid. Studies with purified recombinant [-4]pPSA showed that this proenzyme form is inactive and does not complex with ACT. CONCLUSIONS: These results suggest that the uncomplexed PSA in PCa serum is primarily unclipped PSA that contains a significant fraction of pPSA.     

Adenosine in wide-complex tachycardia

The use of adenosine as a therapeutic and diagnostic tool in wide-complex tachycardia is suggested in the current Advanced Cardiac Life Support (ACLS) guidelines. The ACLS guidelines are now 4 years old, and new information on the safety and efficiency of adenosine in wide-complex tachycardia is available. We review the ACLS recommendations in light of the current available literature. In general, the ACLS recommendations remain reasonable with some important caveats.     

Health effects of methyl tertiary butyl ether (MTBE) in gasoline in Alaska

OBJECTIVES: This ecologic study assessed whether there was a change in health status in Alaska in the winter of 1992-93 after the introduction of MTBE in gasoline. Methyl tertiary butyl ether(MTBE) is used as a fuel oxygenate in the United States and in Europe. In the winter of 1992-93 MTBE was added to gasoline in the cities of Fairbanks and Anchorage, Alaska. The program was discontinued in Fairbanks in December, 1992, but continued in Anchorage until February 28, 1993. METHODS: Outpatient visits for state employees and dependents (n = approximately 28,000) living in Alaska were compared over three winters by analyzing health insurance claims. RESULTS: Odds ratios were calculated. The odds ratios indicated that the winter of 92-93 was not statistically different from previous winters in numbers of claims for upper respiratory illness, bronchitis, headache, or asthma in either Anchorage or Fairbanks. CONCLUSION: There was no increase in claims for respiratory illness in either city after introduction of MTBE.     

Attenuation of alcohol consumption by a novel nontoxic ibogaine analogue (18-methoxycoronaridine) in alcohol-preferring rats

We previously reported that single administration of ibogaine, an indol alkaloid with antiaddictive properties, dose dependently reduced alcohol intake in three strains of alcohol-preferring rats. The present study examined the effect of different doses of a newly developed nontoxic ibogaine analogue, 18-methoxycoronaridine (18-MC), on alcohol intake. Selectively bred alcohol-preferring rats received a single intraperitoneal injection of vehicle or 5, 20 and 40 mg/kg of 18-MC at 9:30 AM, and their consumption of alcohol, water and food was measured for 24 h. Our results demonstrate that a single injection of 18-MC significantly and dose dependently attenuated alcohol consumption and preference and commensurately increased water intake. Only the highest dose of 18-MC significantly decreased food intake. Although the true mechanism of action of 18-MC in suppressing alcohol intake is not yet fully understood, it may, like ibogaine, exert its attenuating effects on alcohol consumption by modulating neurotransmitters believed to be involved in the regulation of alcohol intake.