The dusty atmosphere of the brown dwarf Gliese 229B.

The brown dwarf Gliese 229B has an observable atmosphere too warm to contain ice clouds like those on Jupiter and too cool to contain silicate clouds like those on low-mass stars. These unique conditions permit visibility to higher pressures than possible in cool stars or planets. Gliese 229B's 0.85- to 1.0-micrometer spectrum indicates particulates deep in the atmosphere (10 to 50 bars) having optical properties of neither ice nor silicates. Their reddish color suggests an organic composition characteristic of aerosols in planetary stratospheres. The particles' mass fraction (10(-7)) agrees with a photochemical origin caused by incident radiation from the primary star and suggests the occurrence of processes native to planetary stratospheres.

Detection of daily clouds on Titan.

We have discovered frequent variations in the near-infrared spectrum of Titan, Saturn's largest moon, which are indicative of the daily presence of sparse clouds covering less than 1% of the area of the satellite. The thermodynamics of Titan's atmosphere and the clouds' altitudes suggest that convection governs their evolutions. Their short lives point to the presence of rain. We propose that Titan's atmosphere resembles Earth's, with clouds, rain, and an active weather cycle, driven by latent heat release from the primary condensible species.

Long-term results of selective vagotomy plus pyloroplasty. 12 to 17 year follow-up.

Among an initial series of 103 patients with selective vagotomy plus pyloroplasty for duodenal ulcer, 9 patients died of causes unrelated to ulcer and 7 were lost to follow-up without signs or symptoms of ulcer 8 to 15 years after operation; the remaining 87 patients were followed up for 12 to 17 years. Insulin testing revealed only one inadequate vagotomy in a patient who had a recurrence in the short term. Insulin tests were negative in 61 and negative or adequate in 6 other patients. Complete vagotomy reduced basal secretion effectively in the great majority of patients but not in a small minority. Three patients had antral hyperfunction with persistent hypersecretion despite complete vagotomy as indicated by two negative insulin tests in each patient. Inexplicably, only one of these patients had a stomal ulcer recurrence. Long-term follow-up revealed the development of gastric ulcer in one patient wit stasis from a pyloroplasty stenosed by angulation from adhesions. Three other patients, one with ulcer and two with hemorrhagic gastritis, developed gastric ulceration in the long term despite low acid output and negative insulin tests. Biliary reflux was demonstrated in two of these three patients and was probably the cause of gastric ulcer in the third. Pre- and postoperative cholecystograms in 66 patients showed the formation of gallstones in 4 patients after vagotomy. Another patient who did not undergo cholecystography developed acute cholecystitis from stone. This rate of gallstone formation was the normal expected rate and was not increased as in some series of total vagotomy. Dumping with and without associated diarrhea was the most frequent and troublesome sequela. Postvagotomy diarrhea did not occur. To prevent dumping, and also to decrease acid secretion more effectively, pyloroplasty was abandoned in favor of Maki's pyloruspreserving antrectomy to complement selective vagotomy in 1968.

Diagnosis of papillary stenosis by calibration: follow-up 15 to 25 years after sphincteroplasty.

In 178 patients undergoing elective cholecystectomy for biliary colic, the papilla was calibrated with a no. 10 French catheter through the cystic duct. The catheter passed through the papilla into the duodenum in 94 patients. Six (6 percent) had common duct stones. No postcholecystectomy colic occurred. In 37 patients the catheter was obstructed by papillary stenosis and sphincteroplasty was done. Common duct stones occurred in 17 patients (46 percent), jaundice in 7 and dilatation of the common duct in 6. Cholangiograms failed to detect small stones in seven patients and were of minimal value in positively identifying stenosis. In 49 control patients the papilla was not calibrated. Cholangiograms were normal. Postcholecystectomy colic occurred in seven patients, two of whom underwent subsequent sphincteroplasty. It is concluded that calibration is a worthwhile adjunct to cholangiography. Sphincteroplasty permits passage of small stones that may not be apparent on cholangiograms and are retained by papillary stenosis, and prevents colic (dyskinesia) of stenosis that also may not be apparent on cholangiograms.

Gallstones after vagotomy.

A control group of 53 patients with selective vagotomy plus pyloroplasty was studied with pre- and postoperative cholecystography. At the fourth to seventh years the size and motility of the gallbladders were the same. Gallstones developed in two patients. A series of 91 patients with total vagotomy plus pyloroplasty was studied by similar methods. In 46 patients the gallbladders were grossly dilated and in 30 of the 46 the gallbladders were noncontractile. Gallstones developed in nine of the 46 patients. In the other 45 patients hypotonic dysfunction of the gallbladder was insignificant, and stones developed in only 1 of them. Explanation of these variable results is thwarted by unknown variations in the degree of both hypotonic dysfunction of the gallbladder and lithogenic change in the bile of patients with complete hepatic and complete celiac vagotomy after total vagotomy, and also by the unknown occurrence of incomplete hepatic and incomplete celiac vagotomy in series of allegedly complete total vagotomy. It is concluded that total vagotomy increases the incidence of gallstones, and that this increase occurs primarily in patients with significant hypotonia of the gallbladder. Selective vagotomy prevents these sequelae.

The Marcy repair revisited.

Failure to close the internal ring in transversalis fascia is the primary cause of recurrent indirect inguinal hernia. Removal of the cremaster muscle provides optimal exposure for accurate identification and fascial closure of the ring.

Influx of cometary volatiles to planetary moons: the atmospheres of 1000 possible Titans.

We use a Monte Carlo model to simulate impact histories of possible Titans, Callistos, and Ganymedes. Comets create or erode satellite atmospheres, depending on their mass and velocity distributions: faster and bigger comets remove atmophiles; slower or smaller comets supply them. Mass distributions and the minimum total mass of comets passing through the Saturn system were derived from the crater records of Rhea and Iapetus. These were then scaled to give a minimum impact history for Titan. From this cometary population, of 1000 initially airless Titans, 16% acquired atmospheres larger than Titan's present atmosphere (9 x 10(21) g), and more than half accumulated atmospheres larger than 10(21) g. In contrasts to the work of Zahnle et al. (1992), we find that, in most trials, Callisto acquires comet-based atmospheres. Atmospheres acquired by Callisto and, especially, Ganymede are sensitive to assumptions regarding energy partitioning into the ejecta plume. If we assume that only the normal velocity component heats the plume, the majority of Ganymedes and half of the Callistos accreted atmospheres smaller than 10(20) g. If all the impactor's velocity heats the plume, Callisto's most likely atmosphere is 10(17) g and Ganymede's is negligible. The true cometary flux was most likely larger than that derived from crater records, which raises the probability that Titan, Ganymede, and Callisto acquired substantial atmospheres. However, other loss processes (e.g., sputtering by ions swept up by the planetary magnetic field, solar UV photolysis of hydrocarbons) are potentially capable of eliminating small atmospheres over the age of the solar system. The dark material on Callisto's surface may be a remnant of an earlier, now vanished atmosphere.

Effects of a synthetic facial pheromone on behavior of cats.

OBJECTIVE: TO evaluate the effects of a synthetic feline facial pheromone (FFP) on behavior and food intake of healthy versus clinically ill cats. DESIGN: Original study. ANIMALS: 20 cats were used in each of 2 studies. In each study, 7 cats were considered healthy, and 13 cats were determined to be clinically ill. PROCEDURE: In study 1, cats were assigned either to exposure to FFP (treated group; 4 healthy, 6 ill cats) or to exposure to the vehicle (70% ethanol solution; control group; 3 healthy, 7 ill cats). Cats were placed in a cage containing a small cotton towel that had been sprayed with FFP or vehicle 30 minutes previously. Cats were then videotaped for 125 minutes, and food intake was measured during this period. Videotapes were scored at 5-minute intervals for various behaviors. In study 2, cats were categorized in 1 of 2 groups; group 1 (2 healthy, 8 ill cats) had a cat carrier placed in their cages, and group 2 (5 healthy, 5 ill cats) did not. All cats were exposed to FFP, and 24-hour food intake was measured. RESULTS: Differences between behaviors of healthy versus clinically ill cats were not identified. In the first study, significant increases in grooming and interest in food were found in cats exposed to FFP compared with vehicle. For all cats, significant positive correlations were detected between grooming and facial rubbing, walking and facial rubbing, interest in food and facial rubbing, eating and facial rubbing, grooming and interest in food, and grooming and eating. In the second study, 24-hour food intake was significantly greater in cats exposed to FFP and the cat carrier, compared with cats exposed to FFP alone. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that exposure to FFP may be useful to increase food intake of hospitalized cats.

Development of a method to measure plasma and whole blood choline by liquid chromatography tandem mass spectrometry.

BACKGROUND: Current gold standard markers for myocardial damage are troponins I and T, which are both sensitive and specific for the detection of myocardial infarction, but require up to 6 h to become reliably elevated in serum. Investigation into markers with potential to identify patients with early ischaemic changes is therefore intense. Choline is reported to be prognostic in patients presenting with acute coronary syndromes via its release from ischaemic cell membranes. METHODS: Liquid chromatography tandem mass spectrometry was used to develop a method to quantitate choline in plasma and blood. The method involves addition of a deuterated internal standard to an aliquot of plasma or blood followed by organic solvent addition, which precipitates the proteins in the sample. Preparation was carried out directly into a 96-deep-well plate. Chromatography of choline used a strong cation exchange column and separation used a Waters Atlantis dC18 analytical column positioned directly before the mass spectrometer source, allowing on-line preanalytical clean up of the sample. RESULTS: The lower limit of quantitation was 0.38 micromol/L, linearity was observed up to 754 micromol/L, with a working concentration range of 0.38-224 micromol/L, inter- and intra-assay coefficients of variation were <6% and <4%, respectively. Samples were stable throughout five freeze-thaw cycles and recovery was between 94% and 114%. CONCLUSIONS: The assay was successfully validated in accordance with FDA guidelines and is suitable for quantitation of choline in research and clinical settings.