Biomedical subjects

H Sakata

Publications and source records attributed to H Sakata.

At least 109 records · Page 6Linked to original sources

PubMed1995

Cytotoxic T lymphocyte activity after intravitreal inoculation of herpes simplex virus type I in mice.

We investigated the cytotoxic T lymphocyte (CTL) activity in the cervical lymph nodes and spleen of mice inoculated with herpes simplex virus (HSV) by the corneal or intravitreal route. CTL activity in the spleen was similar in both groups, but CTL activity in the cervical lymph nodes and the delayed-type sensitivity reaction were lower in the intravitreal group than in the corneal group. Our findings indicate that a phenomenon resembling anterior-chamber-associated immune deviation occurred after injection of HSV into the vitreous cavity.

Animals↗

PubMed1995

Auditory brainstem response and temporal bone and brainstem pathology in brainstem death, with special reference to autolysis of red blood cells.

We studied the pathological changes in the temporal bone and brainstem, with particular attention to the autolysis of red blood cells in and around the blood vessels, in six cases of brainstem death determined by auditory brainstem responses (ABRs). Our findings showed that the cochlea, the visceral organs and the spinal cord below a certain level of the cervical segments continued to live after brainstem death. Red blood cells in the vessels of the brainstem and cerebellum exhibited severe autolysis, whereas most red blood cells in the cochlea were preserved. Our findings of autolytic changes in red blood cells in the brainstem, and the preservation of red blood cells in the cochlea, imply initial loss of brainstem function and delayed loss of cochlear function after prolonged absence of ABRs.

Adolescent↗

PubMed1995

[Clinical use of EVAR and OVAR by the dumped rotation test--comparison of normal volunteers and patients with unilateral vestibular nerve section].

Horizontal eye movements in response to either earth vertical axis rotation (EVAR) or off vertical axis rotation (OVAR) by a 10 degree tilted axis were recorded in six normal subjects and three patients with unilateral vestibular nerve section. Both trials consisted of acceleration at approximately 400 deg/sec2 until an angular velocity of 180 deg/sec was reached followed by deceleration at -4 deg/sec2 until rotation ceased. This is the so-called dumped rotation procedure. Total numbers of nystagmic beats and the duration of perrotatory nystagmus in these two different trials were compared. The results were as follows: 1) Total numbers of nystagmic beats in OVAR were significantly larger than in EVAR. 2) The duration of perrotatory nystagmus in OVAR was significantly longer than in EVAR. Only the horizontal semicircular canals were stimulated by angular acceleration in EVAR, whereas both otolith organs and semicircular canals were stimulated on changing the position of the head around the direction of the gravity in OVAR.

Acceleration↗

PubMed1995

Suppression of corneal graft rejection by subconjunctival injection of FK-506 in a rat model of penetrating keratoplasty.

The usefulness of the subconjunctival injection of FK-506 for suppression of allograft rejection was investigated in a rat model of orthotopic penetrating keratoplasty. Fischer rats were used as donors and Dark Agouti rats, as recipients. FK-506 was administered subconjunctivally in a dosage of 0.3 mg/kg/day for 15 consecutive days after penetrating keratoplasty was performed. Allograft rejection occurred within 8 to 10 days after keratoplasty in all untreated rats (n = 6). None of the FK-506-treated rats (n = 6) exhibited graft rejection during the 3-week observation period. Histologic examination showed marked infiltration of mononuclear cells in the stroma of corneal grafts from untreated rats 3 weeks after grafting. Inflammatory cells were only occasionally observed in grafts from FK-506-treated rats. Donor-specific cytotoxic T lymphocyte activity was completely suppressed in FK-506-treated rats 3 weeks after grafting. Our results indicated that subconjunctival injection of FK-506 effectively prevented corneal allograft rejection in a rat model of penetrating keratoplasty.

Animals↗

PubMed1995

Grasping objects: the cortical mechanisms of visuomotor transformation.

Grasping requires coding of the object's intrinsic properties (size and shape), and the transformation of these properties into a pattern of distal (finger and wrist) movements. Computational models address this behavior through the interaction of perceptual and motor schemas. In monkeys, the transformation of an object's intrinsic properties into specific grips takes place in a circuit that is formed by the inferior parietal lobule and the inferior premotor area (area F5). Neurons in both these areas code size, shape and orientation of objects, and specific types of grip that are necessary to grasp them. Grasping movements are coded more globally in the inferior parietal lobule, whereas they are more segmented in area F5. In humans, neuropsychological studies of patients with lesions to the parietal lobule confirm that primitive shape characteristics of an object for grasping are analyzed in the parietal lobe, and also demonstrate that this 'pragmatic' analysis of objects is separated from the 'semantic' analysis performed in the temporal lobe.

Animals↗

PubMed1995

[Neurons in monkey parietal association cortex sensitive to axis orientation].

Patients with parietal lesions may fail to adjust the orientation of the hand to that of the target object or may make errors in judging the orientation of the bar. This suggests that the parietal cortex functions to discriminate the orientation of objects. Therefore, we studied orientation selectivity of the visual neurons of the posterior parietal association cortex of alert behaving monkeys. We recorded 23 neurons that showed selectivity in the axis orientation of visual stimulus in the lateral bank and fundus of the caudal part of the intraparietal sulcus (IPS). Almost all the neurons tested with a slit on the screen responded better to a longer or narrower stimulus. There were also neurons which responded only to three dimensional objects, such as a bar presented in the sagittal orientation tilted forward or backward. The majority of these neurons had wide receptive fields and their responses were position-invariant. These results suggest that the axis orientation selective neurons of the parietal cortex represent orientation of the longitudinal axis of objects in 3-dimensional space.

Animals↗

PubMed1994

Deficit of hand preshaping after muscimol injection in monkey parietal cortex.

In order to assess the functional role of the parietal hand movement region, the anterior part of the lateral bank of the intraparietal sulcus (IPS), area AIP, in the visual guidance of hand grasping, we reversibly inactivated several parts of this area with microinjections of Muscimol in a monkey trained to grasp objects of different shapes, sizes and orientations. During the local inactivation, some of the skilled patterns of finger movements were disrupted in the contralateral hand, due to the lack of preshaping to adjust the finger posture to the object; however, no major deficits in visual reaching were observed. The results suggest that area AIP plays a crucial role in the visual guidance of goal-directed hand movements.

Animals↗

PubMed1994

Functional properties of rotation-sensitive neurons in the posterior parietal association cortex of the monkey.

We studied the functional properties of rotation-sensitive (RS) neurons of the posterior parietal association cortex in detail. We classified 58 neurons as RS neurons on the basis of statistical analysis, to indicate that their responses to rotary movement were significantly greater (P < 0.01) than those to linear movement of the same stimulus. We calculated rotation index, 1-(L/R), in 82 cells, where L/R is the ratio of net response to linear movement to that to rotary movement. All the RS neurons had rotation index greater than or equal to 0.3. The recording site of these RS neurons was localized in the posterolateral part of area PG (area 7a of Vogt), on the anterior bank of the caudal superior temporal sulcus (STS), in the region partly overlapping the medial superior temporal (MST) area. We compared the response of RS neurons to rotation with that to shearing movement as well as to linear movement. In the majority of RS neurons the ratio of shearing response to rotation response (S/R) was smaller than the ratio of linear response to rotation response (L/R), indicating that the response to rotation was not due to a simple combination of linear movements in the opposite direction. Most of the RS neurons responded to the rotary movement of a single spot as well as that of a slit, although the response was smaller (average 70%) for the former. Most of the RS neurons had large receptive fields (60-180 degrees in diameter) and their responses were independent of the position within the receptive field. The responses of most RS neurons increased monotonically with the increase in angular velocity and were also dependent on the size of the stimulus, although the rate of increase was small when the length was more than 10 degrees. The majority of RS neurons (37/58) responded better to rotation in depth than to that in the frontoparallel plane. Some of them (12/37) responded to diagonal rotation rather than to sagittal or horizontal rotation. We found that some depth RS neurons showed reversal in the preferred direction when we used a trapezoidal window-like plate as the rotating stimulus in the monocular viewing condition, just as occurs in the case of the Ames window illusion. The response of some RS neurons (5/7) was enhanced by tracking eye movement.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed1994

Parietal control of hand action.

Recent advances suggest that neurons of the anterior intraparietal area play a critical role in the visual guidance of hand action. The parietal cortex appears to process in-coming binocular visual signals of the three-dimensional features of objects and matches these signals with the motor signals, which come from the ventral premotor cortex, that will be required for hand manipulation of the object.

Animals↗

PubMed1994

[Isolation of methicillin resistant Staphylococcus aureus from nasopharyngeal swabs on admission to a ward for pediatric patients].

Between 1992 and 1993, 2313 nasopharyngeal swabs were taken and cultured from 1665 patients on admission to a pediatric ward at Asahikawa Kosei Hospital. Twenty nine strains of Methicillin resistant Staphylococcus aureus (MRSA) were isolated from 28 patients. The ages of these patients ranged from 2 months to 9 years and 14 patients were younger than 1 year. Their underlying diseases were bronchial asthma in 9 patients, prematurely born infants with chronic lung disease in 4. Fourteen patients had a history of admission during the past 6 months. No patient had infectious diseases due to MRSA.

Child↗

PubMed1994

Induction of cytotoxic T lymphocytes from splenocytes after orthotopic penetrating keratoplasty in the rat.

We used a rat model of orthotopic penetrating keratoplasty to study splenic cell cytotoxicity in the host. DA (RT1avl) rats received grafts of Fischer (F344, RT1lv1) rat corneas. Cytotoxic T lymphocyte (CTL) activity was measured by the cell-mediated lymphocytotoxicity assay using 4/4R.M.-4 cells as target cells. CTL activity became detectable in vitro 2 weeks after grafting and peaked at 3 weeks. This simple method of quantifying CTL activity in the orthotopic penetrating keratoplasty model should provide a reliable tool for studying the CTL response in corneal transplantation.

Animals↗

PubMed1994

Time course of cytotoxic T lymphocyte activity after inoculation of herpes simplex virus into the anterior chamber of mice.

The time course of the activity of cytotoxic T lymphocytes (CTL) was studied after injecting herpes simplex virus (HSV) into the anterior chamber of C3H/He mice and compared with that following corneal inoculation. CTL activity in cervical lymph nodes was suppressed during the 14 days after the inoculation, while that in the spleen increased 2 days earlier compared with the activity after corneal inoculation. The difference between the peaks of CTL activity after inoculation via each route was not significant. Thus, CTLs from the spleen appear to play a role in the immune response defending mice against intraocular infection by HSV.

Animals↗

PubMed1994

Hyperplastic polyps following treatment of acute gastric ulcers.

Although hyperplastic polyps are the most common polyps of the stomach, the etiology of these polyps is not completely understood. We report a 61-year-old woman who developed gastric hyperplastic polyps following acute gastric lesions. She was admitted for endoscopic injection sclerotherapy of esophageal varices. After the end of sclerotherapy, acute gastric lesions developed. For treatment of the lesions, omeprazole was used for 8 weeks followed by famotidine for 8 weeks. At the end of the treatment, she developed multiple gastric hyperplastic polyps, suggesting that acute gastric lesions and/or treatment of the gastric lesions are related to the development of hyperplastic polyps in the stomach.

Esophageal and Gastric Varices↗

PubMed1994

Retinal detachment with tear in the posterior fundus following ocular contusion.

Two unusual cases of rhegmatogenous retinal detachment following contusion to the eyeball showed retinal tears at the posterior fundus close to the optic disc and the large retinal blood vessels. In both cases, the tears were not detected immediately after the injury due to a coexisting vitreous hemorrhage. Both patients were successfully treated by pars plana vitrectomy, air-fluid exchange, and endolaser photocoagulation. During vitrectomies, an adhesion of the vitreous to the flap or the operculum of the tear was observed, with detachment of the remainder of the posterior vitreous from the retina. Vitrectomy allowed a more complete resolution of posterior tractional forces than scleral buckling, and eliminated the vitreous hemorrhage.

Adult↗

PubMed1994

[Intracranial subdural hematoma following spinal anesthesia].

We report a case of intracranial subdural hematoma following spinal anesthesia in a 28-year-old woman. Subdural hematoma is a very rare, but life-threatening complication. When a patient complains of persistent post spinal headache, one should consider the possibility of subdural hematoma and carry out a careful examination, including MRI or CT scan.

Adult↗

PubMed1994

Computerized tomography of two patients with morning glory syndrome.

Morning glory syndrome (MGS), an uncommon optic disc anomaly, is characterized by a funnel-shaped, excavated optic disc surrounded by chorioretinal pigmentary disturbance. Generally, it is an isolated ocular abnormality. The authors describe two patients in whom MGS developed in association with brain abnormalities. In both cases, there was enlargement of the optic nerve that showed increased radiodensity similar to that of sclera and cavum vergae in the brain cavity present in computerized tomography (CT). To our knowledge, the coexistence of MGS, cavum vergae and an enlarged retrobulbar optic nerve showing increased radiodensity have not been previously reported. The findings suggest that MGS may be based on a developmental anomaly involving the brain, and the enlarged optic nerve may be associated with sclera because of the isodensity in CT.

Adult↗

PubMed1994

[Clinical evaluation of biapenem (L-627) in children].

Twenty-four children were treated with biapenem (L-627) and the clinical efficacy and side effects were evaluated. The ages of the patients ranged from two months to 11.5 years and their body weights from 5.9 to 43.5 kg. Doses given were 5.5-12.4 mg/kg every 8 hours for 2.67 to 11.33 days. Those patients who responded well to L-627 treatment included 11 children with pneumonia, 1 with scarlet fever, 1 with cervical lymphadenitis, 2 with cellulitis, 6 with urinary tract infection. Among 21 children, the results were excellent in 13 and good in 8. The drug was well tolerated, although slightly elevated serum concentrations of transaminases occurred in 2 patients among the 24 patients.

Alanine Transaminase↗

PubMed1994

[Pharmacokinetic and clinical studies with L-627 (biapenem) in the pediatric field. Pediatric study group of L-627].

To conduct pharmacokinetic and clinical studies on newly developed L-627 (biapenem) against various infections in pediatrics, a study group was organized and a joint research by 15 institutions and their related hospitals was undertaken. Informed consents of subjects were obtained prior to the study. The obtained results are as follows. 1. Plasma concentrations and urinary excretion Pharmacokinetics of L-627 in children was studied in 29 subjects using 30 minutes intravenous drip infusion of 6 mg/kg and 12 mg/kg. Maximum plasma levels of L-627 was observed at the completion of drip infusion and were 25.1 micrograms/ml with administration of 6 mg/kg and 39.2 micrograms/ml with administration of 12 mg/kg on average. Dose dependency was noted in Cmax and AUC with these doses. Maximum blood levels in all of the 5 participated sucklings under the age of one year were similar to the average. As for urinary excretion, L-627 was excreted 66.0% with administration of 5 mg/kg and 62.3% with 12 mg/kg. 2. Cerebrospinal fluid concentrations Cerebrospinal fluid concentrations ranged from 0.76 to 8.54 micrograms/ml in 30-240 minutes after the completion of drip infusion with dose of 20-40 mg/kg in 9 subjects with purulent meningitis, when they were measured within 3 days after the initiation of the treatment with L-627. 3. Clinical results Thirty-three cases of exclusion and drop-out were deducted from a total of 330 cases, hence 297 cases were evaluated as the subjects in the study for analysis of clinical effects. As for clinical effects in group A where pathogenic bacteria were detected, 166 out of 173 were rated as effective or above, hence the efficacy rate of 96.0% was obtained. In group B where pathogenic bacteria were not detected, 114 out of 124 cases were rated as effective or above, thus the efficacy rate was 91.9%, which is similar to that of the group A. The overall efficacy rate was 94.3% in the entire 297 cases. The rates of "excellent" responses out of the cases rated as effective or above were 62.7% (104/166) in the group A and 55.3% (63/114) in the group B, thus the rate was markedly high in the former group. Efficacy rate for each pathogenic strain was also high, and that in subjects infected by a single pathogenic strain was 96.7% (145/150) and that in subjects infected by two or more pathogenic strains was 91.3% (21/23).(ABSTRACT TRUNCATED AT 400 WORDS)

Age Factors↗