A new technique for probing chirality via photoelectron circular dichroism.

We present a proof-of-principle approach for discriminating chiral enantiomers based on the phenomenon of multiphoton photoelectron circular dichroism. A novel stereo detection setup was used to measure the number of photoelectrons emitted from chiral molecules in directions parallel or anti-parallel to the propagation of the ionising femtosecond laser pulses. In this study, we show how these asymmetries in the ketones camphor and fenchone depend upon the ellipticity of the laser pulses and the enantiomeric excess of the sample. By using a high repetition rate femtosecond laser, enantiomer excesses with uncertainties at the few-percent level could be measured in close to real-time. As the instrument is compact, and commercial turnkey femtosecond lasers are readily available, the development of a stand-alone chiral analysis instrument for a range of applications is now possible.

Perioperative nutritional support for the animal with cancer.

Tumors directly consume nutrients and produce paraneoplastic pathometabolic changes in food use efficiency. In combination with anorexia, negative energy balance and nutrient depletion can be extensive. Refeeding against catabolic changes supports general and specific host defenses. Enteral feeding methods are preferred to parenteral techniques and nutrient profiles are available that appear to favor host repletion.

Showcase, a veterinary case authoring and presentation system.

Showcase is an instructional authoring and case presentation system for veterinary medicine. It is intended to permit instructors and students to deal with clinical case information in a dynamic and interactive way. The programs are distributed as "adware;" and, it is hoped, the case files will be freely shared and distributed.

Idiopathic pleural effusion and pulmonary thromboembolism in a dog with autoimmune hemolytic anemia.

Pleural effusion and pulmonary thromboembolism were diagnosed in a dog with autoimmune hemolytic anemia. Clinical signs of tachypnea, then dyspnea in association with pleural effusion, developed after 10 days of immunosuppressive corticosteroid therapy (greater than 2 mg/kg of body weight/d, PO). The diagnosis of pulmonary thromboembolism was made tentatively on the basis of results of a radionuclide lung perfusion scan and was confirmed by exploratory thoracotomy and lung biopsy. Tachypnea and pleural effusion gradually resolved without specific treatment, and additional episodes of anemia or dyspnea have not been observed. The pathogenesis of these findings was suspected to be related to corticosteroid-induced thrombotic tendencies, persistent thrombocytosis (greater than 800,000 cells/microliters), and vascular injury caused by repeated jugular venous catheterization. Pulmonary thromboembolism should be considered in dogs that develop clinical signs of tachypnea and/or pleural effusion during administration of immunosuppressive dosages of corticosteroids.

Release of clotting factors from photosensitized endothelial cells: a possible trigger for blood vessel occlusion by photodynamic therapy.

Photodynamic treatment of solid tumors results in the occlusion of blood vessels in the treated tissue. We hypothesize that this process is triggered by the release of one or more clotting factors from the photodamaged endothelial cells. Experimental evidence is presented that immediately after photodynamic treatment, cultured endothelial cells start releasing clotting factors into the medium in a dose range of minimal cytotoxicity.

Mechanism of uptake of sulfonated metallophthalocyanines by cultured mammalian cells.

The uptake of several metallophthalocyanine tetrasulfonates by cultured Chinese hamster cells was studied. Uranyl- and chloraluminium were taken up at the highest rate followed by Ni-, Zn-, Cu-, Co- and dichlorosilicon-phthalocyanine tetrasulfonate. The uptake from the growth medium containing 10% serum in which only 15% of the dye is not bound to serum proteins was 5--18-fold slower than in the absence of serum, suggesting that most of the uptake is of free dye. Using gel filtration to separate tightly protein-bound dye from the free dye, binding curves were constructed that varied in slope and saturation values for the different compounds. At saturation, the number of dye molecules bound per serum albumin molecule varied from 1 for vanadyl- and cobalt-, to 4 for uranyl-phthalocyanine tetrsulfonate. Absorption spectra of the various phthalocyanines indicated that under physiological conditions, all dyes, with the exception of chloroaluminum- and dichlorosilicon-phthalocyanine tetrasulfonate, were aggregated. The rate of uptake was unrelated to the state of aggregation. The rate of uptake was temperature dependent at intervals longer than 1 h. At shorter times, very little temperature dependence was observed. These results suggest that the uptake process takes place in two steps. The first step is passive, involving binding of metallophthalocyanine tetrasulfonate to a receptor on the cell membrane, while the second one is active and involves internalization of the bound dye.

Reversal of pentobarbital-induced narcosis by thyrotropin-releasing hormone (TRH) in dogs.

A growing body of evidence suggests that thyrotropin-releasing hormone (TRH), and endogenous brain tripeptide, produces behavioral excitation in a variety of mammalian species. This study evaluated the cardiopulmonary and antidepressant response to a single intravenous (i.v.) bolus of TRH in sodium pentobarbital (33 mg.kg-1) anesthetized dogs. TRH (0.5 and 1 mg) produced a significant dose-dependent decrease in sleeping time (33% and 51%, respectively) when compared to i.v. vehicle (1 ml of 0.9% NaCl)-treated animals. Of interest was the finding that the high (1 mg), but not the low (0.5 mg) dose of TRH significantly (P less than 0.01) increased mean arterial pressure and heat rate. In addition, i.v. TRH (1 mg) significantly (P less than 0.01) decreased tidal volume. A trend toward increased respiratory frequency in TRH-treated dogs was noted, this difference, however, did not reach statistical significance. In conclusion, the results of this study support the view that TRH, and endogenous brain hormone, may have an important clinical application in cases where stimulation of the central nervous system is required.

Diagnostic abdominal paracentesis and lavage in the evaluation of abdominal injuries in dogs and cats: clinical and experimental investigations.

Abdominal paracentesis and lavage, using a peritoneal dialysis catheter, was evaluated clinically for use in detecting intraabdominal injury in 20 dogs and 3 cats. The technique was also evaluated experimentally in 12 dogs in which various volumes of autogenous blood were infused into the abdomen. The procedure was found to be safe, well tolerated, and reliable in the detection of intraabdominal injuries. The volume of free blood in the abdomen of the experimental dogs was accurately determined. The procedure was superior to physical examination and to needle paracentesis for the early detection and evaluation of intraabdominal injuries.