Circadian variation in susceptibility to the ambulation-increasing effect of scopolamine in mice

Circadian variation in susceptibility to the ambulation-increasing effect of scopolamine in mice was investigated. The mice housed under a 12-hr light-dark situation (light period: 6:00-18:00 and dark period: 18:00-6:00) for 5 weeks were administered scopolamine HBr at 0.5 or 2 mg/kg s.c. at one of six times of the day (3:00, 7:00, 11:00, 15:00, 19:00 and 23:00), and the ambulatory activity was measured for 2 hr. Scopolamine induced a dose-dependent increase in the ambulatory activity. In addition, there was a clear circadian variation in the susceptibility to the ambulation-increasing effect of scopolamine. The highest and the lowest overall activity counts during the 2 hr observation period were found when the drug was administered at 3:00 and 15:00, respectively. The present results suggest that the susceptibility to scopolamine in mice is dependent on the time-of-day at which the drug is administered. The reasons which may induce this circadian variation in susceptibility to scopolamine are discussed.     

Postnatal changes in lysosomal enzymes of rabbit ocular tissues

Postnatal changes in acid phosphatase, β-glucuronidase, arylsulfatase and cathepsin D in ocular tissues and liver were studied biochemically. Lysosomal enzymes, except for cathepsin D, showed postnatal age-dependent variations in activity. It is suggested that the changes in lysosomal enzyme activities in ocular tissues are related to eye development.     

Caffeine rapidly decreases potassium conductance of dissociated outer hair cells of guinea-pig cochlea

The effects of caffeine on the outer hair cells (OHCs) freshly dissociated from guinea-pig cochlea were investigated with the whole-cell patch-clamp technique, in both the conventional and the nystatin perforated patch-clamp configurations under voltage-clamp condition. Application of caffeine (> 1 mM for 10–30 s) induced an inward current (I_caffeine) with decrease of conductance in a dose-dependent manner at a holding potential (V_H) of −60 mV. The reversal potential ofI_caffeine (E_caffeine) was close to the K⁺ equilibrium potential. TheI_caffeine was not affected by Ca²⁺-free external solution. The internal perfusion of the Ca²⁺ chelator BAPTA had no effect onI_caffeine. TheI_caffeine was not modulated by the external application of H-8 or staurosporine and by the internal perfusion of GDP-βS. The amplitude ofI_caffeine was the largest at the basal region of OHCs when caffeine was locally applied by the ‘puffer’ method. These results suggest that caffeine induces a decrease in membrane potassium conductance of the OHCs mainly at the basal region without mediating the intracellular signaling pathway.     

Recurrent vitreous hemorrhage in boys with prepapillary arterial loops

We examined recurrent vitreous hemorrhage in two boys with prepapillary arterial loops. Both patients complained of visible floaters in the left eye during gymnastic exercise. Prepapillary arterial loops and vitreous hemorrhage were found in the left eye in both boys. The vitreous hemorrhage decreased gradually, but recurred. Prepapillary arterial loops may be a risk factor for recurrent vitreous hemorrhage in children. The authors have stated that they do not have a significant financial interest or other relationship with any product manufacturer or provider of services discussed in this article. The authors also do not discuss the use of off-label products, which includes unlabeled, unapproved, or investigative products or devices.     

Subtle increase in leukocyte counts in association with drinking and smoking habits

Peripheral leukocyte counts were examined in venous blood of more than 800 male workers exposed to toluene, xylenes, a combination of the two, or neither. Information on the social habits of smoking and drinking was obtained in an occupational health interview. The analysis showed that smoking (15 cigarettes/day on average) induced a significant increase (by 7%) in leukocyte counts, and that an additional increase was induced when the drinking habit was coupled with smoking. Drinking alone tended to increase the leukocyte counts but the effect was statistically nonsignificant, possibly because the number of nondrinking smokers was limited. The study stresses the importance of paying attention to smoking and drinking habits when evaluating hematological parameters such as peripheral leukocyte counts in solvent-exposed workers.     

Large pulmonary arteriovenous malformation with hyperammonemia

A 45-year-old female presented with generalized fatigue, unaccompanied by other symptoms. Investigation revealed severe anemia due to gastric bleeding, and hereditary hemorrhagic telangiectasia accompanied by a large pulmonary arteriovenous malformation (PAVM). Additionally, the presence of hepatic arteriovenous and portovenous shunts indicated hepatic involvement. In addition to hypoxemia due to right-to-left shunting in PAVM, hyperammonemia with normal hepatic function was detected. The large PAVM was successfully managed with surgical resection. Hyperammonemia, persisting despite the hemostasis of gastric bleeding, improved postoperatively in the absence of treatment directed at hepatic involvement. We believe that resection of large PAVM contributed to the improvement of hyperammonemia.     

Two cases of bladder leiomyoma

Two cases of leiomyoma of the bladder are reported. The first case was a 79-year-old female who presented with gross hematuria and frequent urination. Cystoscopy disclosed a large tumor covered by intact mucosa. This lesion was further evaluated by ultrasound, and was thought to be a submucosal tumor of the bladder. The second case was a 43-year-old female who was referred for further investigation of left giant hydronephrosis. During the investigation, submucosal tumor was incidentally found. Concerning the etiology of the hydronephrosis, left ureteral stenosis due to a previous gynecological operation was suspected. These lesions proved to be leiomyoma of the bladder histologically, and were successfully enucleated. Difficulty in diagnosis of this disease and controversy as to the optimal treatment prompted us to report these cases and to review 68 cases reported in the Japanese literature.     

Characteristics of the ambulation-increasing effect of the noncompetitive NMDA antagonist MK-801 in mice: assessment by the coadministration with central-acting drugs.

Characteristics of the ambulation-increasing effect of MK-801, a non-competitive NMDA antagonist, were assessed through the coadministration of MK-801 with various central-acting drugs in mice. The MK-801 (0.3 mg/kg, i.p.)-induced ambulation-increment with a slight ataxia was maximum at around 50 min, and ambulation returned to the control level at about 3 hr after the administration. At 1 mg/kg, the mouse's activity transiently increased, followed by a decrease due to a marked ataxia, which was due to neither stereotypy nor convulsion, for 20-50 min, and then increased again; the ambulation-increment continued even at 4 hr after the administration. Coadministration of MK-801 (0.3 mg/kg, i.p.) with either methamphetamine (2 mg/kg, s.c.), cocaine (20 mg/kg, s.c.), GBR-12909 (10 mg/kg, i.p.), scopolamine (0.5 mg/kg, s.c.), caffeine (10 mg/kg, s.c.) or morphine (10 mg/kg, s.c.) produced a significant enhancement of the effect. However, 0.1 mg/kg of MK-801 had no effect on the interaction with these drugs. On the other hand, the ambulation-increasing effect of MK-801 (0.3 mg/kg) was significantly reduced by haloperidol (0.3 and 0.1 mg/kg, s.c.), ceruletide (0.01 and 0.1 mg/kg, i.p.), reserpine (0.05 and 2 mg/kg, s.c., pretreatment 4 hr before) and nimodipine (1 and 3 mg/kg, i.p.), but it was scarcely modified by alpha-methyl-p-tyrosine (100 and 200 mg/kg, i.p., pretreatment 24 hr and 4 hr before), imipramine (20 mg/kg, i.p.), 6R-L-erythro-5,6,7,8-tetrahydro-biopterin (100 mg/kg, i.p.), pilocarpine (1 and 4 mg/kg, s.c.), N6-(L-2-phenylisopropyl)-adenosine (0.03 and 0.1 mg/kg, s.c.) and naloxone (1 and 5 mg/kg, s.c.).(ABSTRACT TRUNCATED AT 250 WORDS)