Validation of a model predicting enrollment status in a chemoprevention trial for breast cancer

A simple, rapid, and sensitive method which allows us to simultaneously determine bromvalerylurea (BVU) and its three metabolites (3-methylbutyrylurea [MVU], alpha-(cystein-S-yl)isovalerylurea [CVU], and alpha-(N-acetylcystein-S-yl)isovalerylurea [AcCVU]) was investigated by frit-fast atom bombardment liquid chromatography-mass spectrometry (frit-FAB LC-MS). The LC-MS analysis was performed after the solid-phase extraction from tissue and urine samples with a Sep-Pak C18 cartridge. Tissue homogenates and urine were adjusted to pH 4.0 and applied to the cartridges. The retained BVU and its metabolites were eluted from the cartridge with 2 mL of acetonitrile/10 mM ammonium acetate buffer (pH 3.5, 50:50, v/v). The eluate was analyzed by LC-MS, which employs a semimicro type L-column ODS column. The proposed conditions are as follows: mobile phase A, 0.4% glycerol in acetonitrile/10 mM ammonium acetate buffer (pH 3.5) (5:95, v/v); mobile phase B, 0.4% glycerol in acetonitrile; elution mode, linear gradient, 100% A (5 min) to 100% B in 15 min; flow rate, 0.2 mL/min; split ratio, 1:40. Extraction recoveries of BVU and its metabolites were 91.90-97.79% from the spiked liver homogenate and 89.68-96.13% from the spiked urine. The detection limits ranged from 10 to 25 ng/g in selected ion monitoring mode.     

Photocatalytic destruction of organic dyes in aqueous TiO2 suspensions using concentrated simulated and natural solar energy

The photocatalytic destruction of several classes of organic dyes utilizing highly concentrated solar energy is reported. Several commercial samples of anatase TiO₂ varying in particle size and purity were studied to determine catalytic activity with Degussa P25 grade being the most active. When immobilized on glass beads it remained highly active. The rate and extent of decomposition of the organic compounds were determined by UV/Vis spectroscopy and High Performance Liquid Chromatography (HPLC). Complete mineralization was confirmed by total organic carbon analysis as well as wuantitative measurements of CO₂ and various inorganic ions. In general, sulfur in the organic compounds is converted to sulfate ions and nitrogen is converted to ammonium and/or nitrate ions. The effect of increasing the flux of the radiation on the rate of decomposition of the dye was also studied. There is a dramatic rate increase as the flux is increased from 15 “suns” (solar simulator) to 150 “suns” (solar dish concentrator) with the increase being slightly greater than the square root of the increase in flux. This work suggests that potential exists for the use of highly concentrated sunlight in the removal of textile dyes and biological stains from wastewater.     

Association of phosphoinositide-specific phospholipase Cgamma1 with elements of cytoskeleton in A-431 cells

It is shown that phosphoinositide-specific phospholipase C gamma 1 (PLC gamma 1), a substrate of growth factor receptors, is associated with cytoskeleton in A-431 cells. PLC gamma 1 is co-localized only with the cortical actin but not with actin stress fibers. Since EGF receptor is also co-localized with the cortical actin it is concluded that PLC gamma 1 co-localized with actin is mediated by the EGF receptor. After the treatment with cytochalasin B PLC gamma 1 is co-localized with actin aggregates and cytoskeleton elements other than actin. Using double immunofluorescence PLC gamma 1 is shown to be associated with cytokeratin intermediate filaments. The cross-talking of different cytoskeleton elements and their participation in cell signaling is discussed.     

Surgery for cervical myelopathy in geriatric patients

OBJECTIVE: The number of geriatric patients seeking surgical treatment for cervical myelopathy is steadily increasing. Although anecdotal experiences have been good, insufficient data exists in the spine literature concerning this particular group. We decided to review our experience to determine efficacy of surgical management and examine our morbidity with this select group. METHODS: We undertook a retrospective review of all surgical procedures for nontraumatic cervical myelopathy performed at Mt Sinai Medical Center and Jackson Memorial Medical Center between January 1 1987 and June 1 1992, in patients older than 70 years of age (33 men and 18 women). RESULTS: A total of 53 cervical surgical procedures were performed in 51 patients (nine expansile laminoplasties, 20 anterior cervical diskectomies and fusion and 24 decompressive posterior laminectomies). The average hospital stay was 7.7 +/- 3.4 days. Twenty-one (41%) patients required inpatient rehabilitation; the remaining 30 patients received outpatient rehabilitative therapy. The major morbidity rate was 3.9%, and the minor morbidity rate was 5.8%. Perioperative medical complications included cardiac arrhythmias, hypertensive episodes, atelectasis, confusion, urinary dysfunction and hyponatremia. All of these complications resolved except in one patient. The perioperative mortality rate was 2%. Office follow-up was performed for a mean of 11.1 +/- 2.5 months postoperatively. Comparison of preoperative and postoperative functional status was performed using Nurick's criteria as described in the literature. At follow-up, 60.8% of the patients had improvement in their myelopathic symptoms, especially in regard to gait; 33.3% were stabilized and 5.9% had worsened neurological function. CONCLUSION: This study demonstrates that corrective surgical procedures for significant nontraumatic cervical myelopathy in the geriatric population may be performed safely, that is, with acceptable risk of morbidity and reasonable expectation for clinical improvement.     

Oxyhemoglobin desaturation and aberrant carbon dioxide homeostasis during electrically stimulated exercise in a ventilator-dependent tetraplegic patient

This single-subject case examined oxyhemoglobin saturation and alveolar end-tidal carbon dioxide levels in a ventilator-dependent tetraplegic patient undergoing electrical stimulation cycle ergometry. When exercising with a closed tracheostomy cuff under resting ventilator settings (resting intermittent mandatory ventilation; frequency = 6breaths/min, tidal volume = 83.3mL, minute ventilation =5L/min), his oxyhemoglobin saturation decreased from 100% to 92%, while alveolar endtidal carbon dioxide increased linearly to 47mmHg. These undesirable changes were corrected under adjusted intermittent mandatory ventilation conditions (frequency = 12breaths/min, tidal volume = 83.3mL, minute ventilation = 10L/min), during which oxyhemoglobin saturation remained above 98% and the alveolar end-tidal carbon dioxide trend resembled that of ventilator-independent tetraplegic individuals undergoing the same exercise. Because the subject's heart rate was higher under adjusted ventilation conditions, these responses may have been caused by augmented venous return resulting from greater abdominothoracic pumping at the higher breathing frequency. These findings support the need to modify ventilator settings in ventilator-dependent tetraplegic persons while undergoing exercise to maintain oxyhemoglobin saturation and carbon dioxide homeostasis.     

Identification of two Escherichia coli pseudouridine synthases that show multisite specificity for 23S RNA

Several putative Escherichia coli pseudouridine (Psi) synthases have been identified by iterative searching of genomic databases for ORFs homologous to known Psi synthases [Gustafsson et al. (1996) Nucleic Acids Res. 24, 3756-3762]. Of these, yceC and yfiI were proposed to encode Psi synthases which modify 23S rRNA. In the present work, yceC and yfiI were cloned and overexpressed in E. coli, and the encoded enzymes, YceC and YfiI, were purified to homogeneity. Both proteins converted Urd residues of rRNA to Psi, thus confirming their identities as Psi synthases. However, in in vitro experiments both enzymes extensively modified Urd residues of both 23S rRNA and 16S rRNA. Gene-disruption of yceCresulted in the absence of Psi modification at positions U955, 2504, and 2580 of 23S RNA, thus identifying these sites as in vivo targets for YceC. Likewise, yfiI disruption resulted in the absence of Psi modification at positions U1911, 1917, and possibly 1915 of 23S RNA. Disruption of yceC did not affect the growth under the conditions tested, whereas yfiI-disrupted cells showed a dramatic decrease in growth rate. Since YceC and YfiI hypermodify RNA in vitro, factors in addition to ribonucleotide sequence must contribute to the in vivo specificity of these enzymes.     

Diaphragm EMG measured by cervical magnetic and electrical phrenic nerve stimulation

The purpose of the study was to compare electrical stimulation (ES) and cervical magnetic stimulation (CMS) of the phrenic nerves for the measurement of the diaphragm compound muscle action potential (CMAP) and phrenic nerve conduction time. A specially designed esophageal catheter with three pairs of electrodes was used, with control of electrode positioning in 10 normal subjects. Pair A and pair B were close to the diaphragm (pair A lower than pair B); pair C was positioned 10 cm above the diaphragm to detect the electromyogram from extradiaphragmatic muscles. Electromyograms were also recorded from upper and lower chest wall surface electrodes. The shape of the CMAP measured with CMS (CMS-CMAP) usually differed from that of the CMAP measured with ES (ES-CMAP). Moreover, the latency of the CMS-CMAP from pair B (5.3 +/- 0.4 ms) was significantly shorter than that from pair A (7.1 +/- 0.7 ms). The amplitude of the CMS-CMAP (1.00 +/- 0.15 mV) was much higher than that of ES-CMAP (0.26 +/- 0.15 mV) when recorded from pair C. Good-quality CMS-CMAPs could be recorded in some subjects from an electrode positioned very low in the esophagus. The differences between ES-CMAP and CMS-CMAP recorded either from esophageal or chest wall electrodes make CMS unreliable for the measurement of phrenic nerve conduction time.