A new method for assessing motion-in-depth perception in strabismic patients.

AIM: In strabismus clinics, stereoscopic depth perception is usually examined using static stimuli, but these stimuli do not necessarily allow assessment of the ability to perceive motion in depth. We assessed the ability to perceive motion-in-depth perception using a novel stereo motion test that we developed and compared with that to perceive static depth perception using a conventional stereo test in strabismic patients. METHODS: To investigate motion-in-depth perception in patients with strabismus, we developed a stereo motion test using four types of computer-generated dynamic visual stimuli. Three of them are random dot stereograms of two parallel planes moving in depth. The patient is asked to indicate the planes' direction of rotation in depth (in the first and second types) or the presence/absence of motion-in-depth signal (in the third type). The fourth type of stimulus was a random dot stereogram of a rotating cylinder. The upper and lower parts of the cylinder rotate in opposite directions, and the patient is asked to indicate the position of the border between the two parts. Threshold disparity was defined as the disparity (relative disparity between the nearest and farthest points of the planes or the cylinder) that gives a critical level of performance with the method of limit. The conventional Titmus stereo test using static visual stimuli was used to assess static depth perception. The measurements were performed in 52 strabismic patients, aged between 4 and 38 years old, who visited Tokyo Medical University Hospital between January 2003 and July 2004. RESULTS: The results showed a poor correlation in the threshold of individual patients between the stereo motion test and conventional Titmus stereo test. For example, the ability to perceive motion in depth (disparity threshold <500 sec of arc) was demonstrated in three of seven patients who were not able to perceive depth using static stimuli (0/9 for Titmus circle). These results suggest that the process of the dynamic element of binocular depth perception is preserved in some of the strabismic patients who lack static stereopsis. CONCLUSION: This study indicates the importance of testing motion-in-depth perception as well as static depth perception in assessing stereopsis in strabismic patients.

The characteristics of static visual fields in children with psychogenic visual disturbances.

PURPOSE: It is well-known that patients with psychogenic visual disturbances (PVD) exhibit characteristic kinetic visual fields. Even when the kinetic fields are normalized, the static fields of PVD children frequently remain abnormal. To verify this finding, we performed static perimetry on those children whose kinetic fields were initially normal or which normalized during the follow-up period, and compared the results with those of children with psychosomatic disorders (PSD) and normal children. METHODS: We examined 9 PVD children (17 eyes), 16 PSD children (32 eyes), and 16 normal children (16 eyes). Program 30-2 or 24-2 of the Humphrey Field Analyzer was used in the examinations on all subjects. RESULTS: The average mean deviation (MD) of the PVD group was significantly lower than that of the other groups (P <. 01). False negative errors and short-term fluctuations were significantly higher in the PVD group than in the other groups (P <. 05). CONCLUSION: Although PVD and PSD children possess a similar underlying psychological dysfunction, their performances in visual field testing proved to be quite different. In the PVD group, even when kinetic fields were normal, functional visual field loss in the static fields was common and had characteristic response properties.

Does the histaminergic system play a role in spinal nociception?

The author studied whether the histaminergic system is involved in spinal nociception or not. A nociception-related, slow ventral root potential of rats, which is an integrated output of motoneurons, was recorded as an index of the intensity of nociception when an electric stimulation was applied to the dorsal root. Histamine dissolved in an artificial cerebrospinal fluid caused small reduction in the potential; however, mepyramine (10 nM to 10 microM, as an H1 receptor antagonist), ranitidine (1 nM to 1 microM, as an H2 receptor antagonist), R(-)-alpha-methylhistamine (2 pM to 200 nM, as an H3 receptor agonist), and thioperamide (1 nM to 10 microM, as an H3 receptor antagonist) dose-dependently reduced the potential down to around a half of each control level. These results indicate that the histaminergic system may affect the spinal withdrawal reflex.

Comparison of tympanic, esophageal and blood temperatures during mild hypothermic cardiopulmonary bypass: a study using an infrared emission detection tympanic thermometer.

OBJECTIVE: Tympanic temperature can be obtained instantaneously using an infrared emission detection (IRED) thermometer. Its accuracy has been documented in a variety of clinical settings, but its performance at low body temperatures is still unknown. In this study we evaluated its performance during coronary artery revascularization surgery in which mild hypothermic cardiopulmonary bypass (CPB) was used. METHODS: Thirty adult patients undergoing coronary artery bypass graft surgery were enrolled in the study. Tympanic temperature obtained using IRED thermometry (Tt1) was compared with core temperatures from the esophagus (Te), and venous blood of CPB (Tv) before, during, and after CPB. We also measured tympanic temperature using a thermocouple probe (Tt2) in 16 of the 30 patients in order to study the agreement between the two methods. Values for correlation coefficients and limits of agreement were computed to assess the degree of agreement among the temperatures obtained. RESULTS: The highest agreement with Tv during CPB was obtained from Tt1 (r = 0.94, 0.41 +/- 1.73, limits of agreement) and from Te (0.91, 0.36 +/- 2.46). Tt1 also showed good agreement with Tt2 during surgery. CONCLUSIONS: Infrared tympanic thermometry is a reliable, alternative method to measure tympanic temperature and may be useful to assess core temperature in both normothermic and mild hypothermic conditions.

[Effects of halothane, isoflurane, enflurane, and sevoflurane on the monosynaptic reflex response in the isolated spinal cord of newborn rats].

Monosynaptic reflex responses (MSRs) in the isolated spinal cord of newborn rats were elicited in the ventral root by stimulation of the ipsilateral dorsal root. MSRs were considered to be mediated by non-NMDA class glutamate receptors. We studied the depressant effects of halothane, isoflurane, enflurane, and sevoflurane on MSR amplitudes as a function of anesthetic concentration comparing with MAC value of each anesthetics. The spinal cord of newborn rats were rapidly dissected out, and placed in a chamber superfused with artificial cerebrospinal fluid (ACSF, pH 7.4, 34 degrees C) equilibrated with 95% O2 - 5% CO2. Anesthetic gases were delivered with specific vaporizers and bubbled in the ACSF. Each anesthetic concentration was determined by gas chromatography. Either of the anesthetics reversibly depressed MSR amplitudes in a concentration dependent fashion. Concentration-response curves for MSR amplitudes were constructed and the concentrations which produced a half-maximum inhibition (IC50) were 0.56, 0.65, 0.97 and 1.18 mM for halothane, isoflurane, enflurane, and sevoflurane, respectively. These IC50 values correlated well with those of MAC values (r = 0.999, P < 0.001) obtained from adult rats in an in vivo condition. The MSR response in the isolated spinal cord of newborn rats is considered as a useful model for analysis of potency of volatile anesthetics.

Isolation and structure elucidation of the major photodegradation products of pirmenol hydrochloride.

Column chromatography, thin-layer chromatography, high-performance liquid chromatography, nuclear magnetic resonance spectrometry, and high-resolution mass spectrometry were employed to separate and identify the photodegradation products of pirmenol hydrochloride [(+/-)-cis-alpha-[3-(2,6-dimethyl-1-piperidinyl)propyl]-alpha-phenyl-2- pyridinemethanol monohydrochloride monohydrate], a new antiarrhythmic drug. A methanol solution of pirmenol was irradiated using a low-pressure mercury lamp. The solution afforded four major degradation products, three of which were identified as 3-(cis-2,6-dimethylpiperidinyl)propyl 2-(2-pyridyl)phenyl ketone, 2-(2-pyridyl)benzoic acid, and methyl 2-(2-pyridyl)-benzoate. The degradation followed apparent-first-order reaction kinetics. In addition, the possible photodegradation pathways are discussed with reference to reaction mechanisms.

Does a lidocaine patch reduce the pain at venous cannulation in adults?

In this study we evaluated whether a lidocaine patch reduces the pain relating to a venous cannulation in adults. The patch is consisted of the base containing 50% lidocaine on a thin polyester membrane. Its surface area is 15 cm2. Twenty-six adult patients scheduled for elective surgery (11 males and 15 females) were randomly divided into two groups according to application periods: Group A for 15 min and Group B for 30 min. Either the dorsal part of the hand or the radial side of the wrist was chosen and covered with the patch. Pain assessment was made by patients using a 0-100 point visual analog scale (VAS). In 7 patients of Group A, plasma lidocaine levels were measured 15 min after application by homogeneous enzyme immunoassay. The levels were further measured 30 and 60 min after application in 3 of those patients. The mean VAS score was 28.4 +/- 13.1 (mean +/- SD) for Group A and 51.8 +/- 15.9 for Group B, and the difference was statistically significant (P < 0.05). Plasma lidocaine levels were always below 0.2 microg.ml(-1). The results indicate that the skin was partially anesthetized by the lidocaine patch. A lidocaine patch may be useful and safely applicable for venous cannulation in adult patients.

Intralysosomal pH and release of lysosomal enzymes in the rat liver after exhaustive exercise.

The mechanism underlying exhaustive exercise-induced release of lysosomal enzymes was studied in the rat liver. Exhaustive exercise resulted in the release of beta-glucuronidase and cathepsin D, but not beta-glucosidase and acid phosphatase, into the blood and cytosol, suggesting that the release of lysosomal enzymes is not due to disruption of lysosomal membranes. The intralysosomal pH of the liver, which was approximately 5.5 at the resting level, rose significantly after exhaustive exercise to pH 6.3. In vitro, beta-glucuronidase and cathepsin D were released at an intralysosomal pH exceeding 6.2. In contrast, beta-glucosidase and acid phosphatase were not released. The elevation of intralysosomal pH reduced the aggregation of beta-glucuronidase and cathepsin D. The rate of ammonia accumulation increased markedly in the lysosome-enriched subcellular fraction after exercise. There was a positive relationship between the rate of ammonia accumulation and the elevation of intralysosomal pH in vitro. Lysosomes isolated after exhaustive exercise showed significantly increased osmotic fragility. Our findings suggest that, during exhaustive exercise, the accumulation of ammonia in lysosomes leads to the elevation of intralysosomal pH, resulting in the reduced aggregation of certain lysosomal enzymes. Thus, less aggregated lysosomal enzymes may be released into the cytosol through the lysosomal membrane, the permeability of which has been increased.