Ketamine Suppresses Platelet Aggregation Possibly by Suppressed Inositol Triphosphate Formation and Subsequent Suppression of Cytosolic Calcium Increase

Background: Ketamine has been shown to suppress platelet aggregation, but its mechanisms of action have not been defined. The purpose of the current study is to clarify the effects of ketamine on human platelet aggregation and to elucidate the underlying mechanisms of its action.

Methods: Platelet aggregation was measured using an eight-channel aggregometer, and cytosolic free calcium concentration was measured in Fura-2/AM-loaded platelets using a fluorometer. Inositol 1,4,5-triphosphate (IP3) was measured with use of a commercially available IP3 assay kit. To estimate thromboxane A2 (TXA2) receptor binding affinity and expression, Scatchard analysis was performed using [3H]S145, a specific TXA2 receptor antagonist. TXA2 agonist binding assay was also performed. The membrane-bound guanosine 5'-triphosphatase activity was determined using [[gamma]-32P]guanosine triphosphate by liquid scintillation analyzer.

Results: Ketamine (500 [mu]m) suppressed aggregation induced by adenosine diphosphate (0.5 [mu]m), epinephrine (1 [mu]m), (+)-9,11-epithia-11,12-methano-TXA2 (STA2) (0.5 [mu]m), and thrombin (0.02 U/ml) to 39.1 +/- 30.9, 46.3 +/- 4.3, -2.0 +/- 16.8, and 86.6 +/- 1.4% of zero-control, respectively. Ketamine (250 [mu]m-1 mm) also suppressed thrombin- and STA2-induced cytosolic free calcium concentration increase dose dependently. Although ketamine (2 mm) had no effect on TXA2 receptor expression and its binding affinity, it (1 mm) suppressed intracellular peak IP3 concentrations induced by thrombin and STA2 from 6.60 +/- 1.82 and 4.39 +/- 2.41 to 2.41 +/- 0.98 and 1.90 +/- 0.86 pmol/109 platelets, respectively, and it suppressed guanosine triphosphate hydrolysis induced by thrombin (0.02 units/ml) and STA2 (0.5 [mu]m) to 50.3 +/- 3.2 and 67.5 +/- 5.5%versus zero-control, respectively.     

Alternative Expression of a Chitosanase Gene Produces Two Different Proteins in Cells Infected withChlorellaVirus CVK2

SeveralChlorellavirus CVK2 proteins had chitosanase and/or chitinase activities. A gene coding for an ORF of 328 amino acids (aa) with a predicted molecular mass of 36,769 Da was cloned from the viral genome. The predicted amino acid sequence of an N′-portion (174 aa) of this gene product (vChta-1) showed 22 to 25% identity with various bacterial chitosanases. A glutathioneS-transferase (GST)–vChta-1 fusion protein had strong chitosanase activity. Western blot analysis with antisera raised against the vChta-1 protein identified two proteins of 37 and 65 kDa in virus-infectedChlorellacells beginning at 240 min postinfection and continuing until cell lysis. The larger protein was packaged in the virion, while the smaller one remained in the cell lysate. Both chitosanase proteins were produced from the single gene,vChta-1,by a mechanism of alternative gene expression.     

Antiepileptic effects of CNK-602A, a novel thyrotropin-releasing hormone analog, on absence-like and tonic seizures of spontaneously epileptic rats.

The effects of CNK-602A (N-[(6-methyl-5-oxo-3-thiomorpholinyl) carbonyl]-L-histidyl-L-prolinamide), a novel thyrotropin-releasing hormone related analog, were investigated on absence-like seizure and tonic convulsion in the spontaneously epileptic rat (SER), which is a genetically defined double-mutant. When CNK-602A of 0.2-1 mg/kg was given intravenously to the animal, there were no changes in the background EEG except for an increase in low-voltage fast waves concomitant with behavioral alertness. However, CNK-602A suppressed absence-like seizure and tonic convulsion in a dose-dependent manner for over 1 h. These antiepileptic effects of CNK-602A on both seizures were antagonized by pretreatment with haloperidol (1 mg/kg, i.p.). It was found, using a brain in vivo microdialysis method, that CNK-602A at a dose of 1 mg/kg, which inhibits the seizures, increased the release of dopamine in the caudate nucleus. These results suggest that CNK-602A inhibits the seizures of SER in a similar manner to thyrotropin-releasing hormone (TRH), probably by increasing the release of dopamine in the central nervous system. In addition, the antiepileptic effects of CNK-602A were more potent and lasted longer than those of TRH.     

Discrimination of spinal fracture with various bone mineral measurements

For several different bone mineral measurements and various skeletal sites, we compared capability to discriminate between women in various age decades with and without spinal fracture, and attempted to identify the most effective cutoff level in discrimination of spinal fracture. The subjects were 88 women aged 50–59 years (including 32 with fracture), 95 women aged 60–69 years (including 54 with fracture), and 34 women aged 70–79 years (including 18 with fracture). Spinal trabecular and cortical bone mineral density (BMD) were measured using quantitative computed tomography (CT), and spinal, radial (ultra-distal, 10% distal and 33% distal), and calcaneal BMD were measured by dual X-ray absorptiometry. These BMD values were obtained in each subject on the same day. Three statistical techniques—Student's t-test, the logistic regression analysis, and the receiver operating characteristics (ROC) analysis— were applied and accuracy was calculated using the various cutoff values. The capability to discriminate between women with and those without fracture using these BMD values was different among the three age groups. In women aged 50–59 and 60–69 years, all measurements showed good capabilities for discriminating women with fracture. In women aged 70–79 years, these measurements showed lower capability than in those aged 50–59 and 60–69 years, but among them, the calcaneal and ultradistal radial BMD showed relatively good capability. The 10% and 33% distal radial BMD values were not useful in the detection of the high risk women with fracture. The cutoff BMD values for discrimination of women with fracture varied according to the sites and methods of measurement. For each specific age group, the most suitable measurement methods and the appropriate skeletal sites should be considered, and the effective cutoff values to discriminate those with fracture may differ according to the measurement methods, the skeletal sites examined, and age. Received: 5 February 1996 / Accepted: 18 June 1996     

Influence of ileal pouch capacity and anal sphincteric function on the clinical outcome after ileal pouch-anal anastomosis

This study was designed to determine the influence of ileal pouch capacity and anal sphincteric function on the clinical outcome after ileal pouch-anal anastomosis. A total of 24 patients who had undergone ileal pouch-anal anastomosis (J pouch) for ulcerative colitis were studied. The 24-hour stool frequency was found to be inversely correlated with the sensitivity threshold volume (STV), maximal tolerance volume (MTV), and distensibility, but was independent of the maximal resting pressure and maximal squeeze pressure. Patients experiencing nocturnal fecal incontinence had maximal resting pressures that were significantly lower than those of nocturnally continent patients. Among the patients with fecal incontinence, those with frequent soiling had lower resting pressures, STV, and distensibility than the patients with intermittent spotting. In addition, the STV in patients needing nocturnal evacuation were lower than those of patients who did not evacuate after falling asleep. The conclusions are as follows. Both stool frequency and the need for nocturnal pouch evacuation correlated directly with pouch volume. Anal incontinence was more common in patients with low internal sphincteric function. In addition, frequent and gross nocturnal incontinent patients demonstrate a worse function in both the anal sphincter and reservoir than those with intermittent spotting.     

Ethylene vinylacetate copolymer particles dissolved in polyvinyl alcohol (2,000-mer) solution as an embolic material for vascular anomalies

We have prepared a new material for embolisation: ethylene vinylacetate copolymer dissolved in polyvinyl alcohol. When in contact with blood, polyvinyl alcohol rapidly becomes a soft gel, which is accompanied by wedging of the ethylene vinylacetate copolymer. We analysed the histopathology of intra-arterial microemboli in rats, after intracarotid injection of this material. We confirmed that it was applicable to embolisation for neurosurgical treatment.     

A case of rheumatoid arthritis complicated with idiopathic thrombocytopenic purpura and Hashimoto's disease

A 37 year old nurse with the rare combination of idiopathic thrombocytopenic purpura (ITP), Hashimoto's thyroiditis and rheumatoid arthritis (RA) was reported. In 1983, six years before her final diagnosis was made, she presented with purpura over her extremities and swelling of the cervical lymph nodes. Laboratory findings showed the following: platelet count 15 x 10(3)/microliters, the number of megakaryocyte without platelet production in bone marrow was increased, platelet life span (T1/2) 11 min. A diagnosis of ITP was made. In 1984 goiter was noticed. Laboratory data were as follows: T3 502ng/ml, T4 27.0 micrograms/dl, thyroid test x 1,600, microsome test x 409,600. She was diagnosed as having ITP and Hashimotoxicosis. She had been uneventful except temporary hyperthyroidism until 1989 when she developed morning stiffness, polyarthralgia, swelling of PIP joints, contracture of elbow joints and hallux valgus. Laboratory investigation were reported as follows. ESR 111mm/h, platelet count 31 x 10(3)/microliters, platelet associated IgG 800ng/10(7) pl, antinuclear antibody x 2,560, rheumatoid factor 1+, microsome test x 1,600, anti-DNA antibody 3U/ml. Anti-Sm antibody and anti-RNP antibody were not detected. The LE cell test was negative. Schirmer test and sialography were interpreted as normal. These findings confirmed the diagnosis of RA in addition to ITP and Hashimoto's thyroiditis. The combination of RA, ITP and Hashimoto's thyroiditis is extremely rare although these three disorders are classified as autoimmune disease.     

Techniques for difficult cases of laparoscopic cholecystectomy

Our basic techniques for the management of difficult cases of laparoscopic cholecystectomy (LC) are presented in this article. If access to Calot's triangle cannot be gained safely, dissection should be started at the fundus or body of the gallbladder (GB), rather than the neck (fundus-first method). In cases with a short and wide cystic duct, a transfixing suture should be applied for ligation instead of clipping. EndoGIA is useful for ligating and transecting this case to avoid a subsequent stricture caused by normal method of ligation. Intraoperative cholangiography should be performed near the neck of the GB in cases in which orientation is lost during dissection. More dissection should be performed in the direction of the junction of the bile ducts after orientation is regained. In cases with GB filled with stones accompanied by severe fibrosis, part of the GB is incised to remove the stones and expose the lumen of the GB. Confluence stones can be removed by placing an incision on the GB side of the junction of the duct. The incised part is closed with suture. A cystic tube (C-tube) is placed in the common bile duct through the cystic duct for decompression. In more difficult cases in which dissection cannot be started safely at any location, the body and the fundus of the GB are excised, and a drain is placed at the neck of the GB. Dissection can be carried out from the main surgeon's or the assistant's side depending on the situation, and cooperation between the two surgeons is mandatory to achieve safe LC in difficult cases. When performing the LC, one must have a low threshold for converting to open surgery if injuries cannot be managed safely.