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Biomedical subjects

Y Ishiwata

Publications and source records attributed to Y Ishiwata.

At least 55 records · Page 3Linked to original sources
PubMed1994

Studies on the antiviral activity of propagermanium with immunostimulating action.

The effects of propagermanium (3-oxygermylpropionic acid polymer) on various virus-infected mice were investigated. Propagermanium did not inhibit the multiplication of various DNA or RNA viruses in vitro. Oral administration of propagermanium in mice infected with herpes simplex virus type I (HSV-1) significantly prolonged the mean survival days. The efficacy of propagermanium at doses of 1 and 10 mg/kg daily was 13.4 +/- 2.3 and 14.2 +/- 2.3 mean survival days in comparison with 7.7 +/- 0.5 mean survival days at control group. In vaccinia virus-infected mice, oral doses of propagermanium ranging from 0.2 to 10 mg/kg suppressed the number of pocks on the tail which induced by the virus. Propagermanium (0.5-10 mg/kg) orally given to HSV-1-infected mice induced cytotoxic T lymphocytes (CTL) against HSV-1 antigen. In addition, propagermanium (1-10 mg/kg) enhanced interferon-gamma (IFN-gamma) induction in mice treated with Mycobacterium bovis (BCG). In mice spleen cells cultured with Concanavalin A, 0.1 to 10 micrograms/ml of propagermanium stimulated interleukin 2 (IL-2) production. It seems likely that the antiviral activity of propagermanium was exerted via enhancement of host immune resistance against viral infection.

Adjuvants, Immunologic↗
PubMed1992

Control of trigeminal motoneurons from the cerebellar interpositus nucleus of the guinea pig.

1. Effects of stimulation of the cerebellar interpositus nucleus (IPN) on jaw reflexes and trigeminal motoneurons were studied along with the route responsible for the effects in ketamine-anesthetized guinea pigs. 2. Stimulation in the IPN evoked a bilateral, ipsilaterally dominant, short-latency reciprocal effect on jaw reflexes: a depression of the jaw-closing masseteric reflex and a facilitation of the jaw-opening digastric reflex. This reciprocal phase was followed by a non-reciprocal facilitatory phase. 3. Stimulation in the IPN evoked a short-latency, strychnine-sensitive inhibitory postsynaptic potential (IPSP) followed by a rebound depolarizing potential in the jaw-closing masseter motoneurons (MAMNs) and an excitatory postsynaptic potential (EPSP) in the jaw-opening anterior digastric motoneurons (ADMNs). The time course of the intracellular response of MAMNs to the IPN stimulation was similar to that of the IPN-induced effects on the jaw-closing reflex. In contrast, the duration of the IPN-induced EPSP in ADMNs was shorter than the IPN-induced facilitation of the jaw-opening reflex. 4. After the IPN neurons were lost by injection of kainic acid into the nucleus, the reciprocal effect of the IPN stimulation on the jaw reflexes could not be seen, even though the projection fibers from the trigeminal sensory nucleus to the IPN remained essentially intact. 5. Stimulation in the superior cerebellar peduncle (SP) induced the same reciprocal effect on the jaw reflexes as the IPN stimulation. A lesion of the SP virtually abolished the reciprocal effect on the jaw reflexes of stimulation in the IPN ipsilateral with reference to the SP lesion. 6. Transection of the brain stem at the level immediately caudal to the red nucleus did not affect the reciprocal effect of the IPN stimulation on the jaw reflexes. 7. We conclude that the IPN output bilaterally induces an inhibition of jaw-closing MAMNs and an excitation of jaw-opening ADMNs, oligosynaptically by way of a direct cerebelloreticular projection system via the SP.

Animals↗
PubMed1990

A new intracranial Silastic encircling clip for hemostasis. Technical note.

A new encircling clip made of a silicone tube has been designed for treating accidentally injured cerebral vessels. No special holders are necessary. This clip can be tailored depending on the shape of the injured vessel. The clip is a simple and effective tool for achieving complete hemostasis.

Cerebral Arteries↗
PubMed1990

Effects of proxigermanium on interferon production and 2',5'-oligoadenylate synthetase activity in the lung of influenza virus-infected mice and in virus-infected human peripheral blood mononuclear cell cultures.

Proxigermanium (SK-818) is a synthesized organic germanium compound having various biological activities. The effects of proxigermanium on interferon (IFN) production in mice infected with influenza virus and virus-infected human peripheral blood mononuclear cells (hPBMC) were investigated. Proxigermanium alone did not induce IFN production in normal mice or in hPBMC without viral infection. On the other hand, proxigermanium enhanced alpha/beta IFN production in viral-infected mice and hPBMC. Since proxigermanium is known to have antiviral activity in vivo but not in vitro, it is likely that the IFN production augumenting activity of proxigermanium is involved in its antiviral activities.

2',5'-Oligoadenylate Synthetase↗
PubMed1990

[Effect of pulsed electromagnetic fields (PEMF) on human periodontal ligament in vitro. Alterations of intracellular Ca2+].

The concept of orthodontic tooth movement is based on the hypothesis that teeth move as a result of the biological response of periodontal tissues to the mechanical forces applied. There is a widely held hypothesis that mechanical stress generates an electrical signal which sets in motion the subsequent events, as in bone exposed to mechanical forces electrical currents are produced affect bone growth and remodeling. This implies a transduction mechanism which translates the electrical signal into a biochemical message, recognizable by the cellular machine. This study is aimed at the identification of the message and the investigation of its control. In fact, the effect of Pulsed Electromagnetic Fields (PEMF) on the intracellular second messenger, cytoplasmic Ca2+ in Human Periodontal Ligament Fibroblasts (HPLF) was investigated. The resting intracellular ionized calcium concentration ([Ca+2]i) of HPLF cells was 232.7 +/- 25.0 nM, and with PEMF [Ca2+]i increased from 12 hrs to 499.0 +/- 115.5 nM up to 12 hrs, then reached to a steady level through 24 hrs. The PEMF were also found to decrease the responses towards epidermal growth factor (EGF) and serum, when the degree of response was based on the intracellular Ca2+ transient. These effects of PEMF were mimicked by 12-0-tetradecanoyl phorbol 13-acetate (TPA), a potent activator of protein kinase C. Some reports have suggested that fibroblasts of the periodontal ligament contain high alkaline phosphatase (ALPase) activity as much as osteoblast. Since similar results concerning the [Ca2+]i were obtained in osteoblast (OB)-like cells, this experiment also supports the hypothesis that fibroblasts of periodontal ligament have osteoblastic features.

Bone Remodeling↗
PubMed1990

[Phosphotyrosine phosphatase activity of human periodontal ligament fibroblasts (HPLF)].

The periodontal ligament is a non-calcified connective tissue involved in the remodeling processes associated with mechanical stresses such as occlusion and mastication. This study was attempted to explore the characterization of phosphotyrosine phosphatase (PTPase) on the cell attachment and spreading of human periodontal ligament fibroblasts (HPLF). HPLF obtained by the explantation of human periodontal ligaments were cultured with vitamin D3 (D3) and dexamethasone (Dex) for 12 days. At 7 day culture, PTPase and ALPase activities were assayed with the substrates of phosphotyrosine and p-nitrophenylphosphate, respectively. Although ALPase activity of HPLF was dramatically increased by D3 and Dex, PTPase activity was not altered. After the quiescent HPLF were cultured with serum-free MCDB 107, the conditioned medium of HPLF (HPLF-CM) was coated on a hydrophobic dish. And then, HPLF were inoculated and cultured with 32Pi on the dish. PTPase activity of HPLF was decreased compared with control medium, however, the incorporation of 32Pi added in the medium was increased 2-fold. Therefore, HPLF possess the PTPase which may dephosphorylate a phosphotyrosine of phosphoproteins, which can regulate the cell proliferation. The cell attachment and spreading factors contained in HPLF-CM might alter the processes of phosphorylation and dephosphorylation of phosphoproteins.

Alkaline Phosphatase↗
PubMed1989

[Comparison of five modes of dialysis in neurosurgical patients with renal failure].

In neurosurgical patients with renal failure, dialysis entails specific problems, chief of which is increased intracranial pressure and progressive brain edema as a result of rapid lowering of the serum osmolality. Another major problem is a tendency to hemorrhage, in response to either systemic heparinization or insufficient dialysis. The authors describe the results obtained with hemodialysis (HD), continuous arteriovenous hemofiltration (CAVH), continuous ambulatory peritoneal dialysis (CAPD), continuous peritoneal dialysis (CPD), and intermittent peritoneal dialysis (IPD). Nine patients were treated with HD, one with CAVH, five with CAPD or CPD, and two with IPD. Three of the six patients treated with continuous dialysis (CAVH, CAPD, and CPD) died, whereas intermittent dialysis (HD and IPD) carried an 82% mortality rate (nine of 11 patients). The causes of death were progressive brain edema in three cases, intracranial hemorrhage in three, gastrointestinal bleeding in three, overhydration due to insufficient dialysis in one, septicemia in one, and rupture of a cerebral aneurysm in one. Continuous dialysis appeared to be superior to intermittent dialysis in these neurosurgical patients in that it produced less brain edema and was less often associated with hemorrhage due to insufficient dialysis. In HD and CAVH, systemic heparinization was also thought to account for the high incidence of hemorrhage. However, CAVH with short half-life anticoagulants may be useful in patients who have abdominal complications and are therefore not suitable candidates for peritoneal dialysis.

Adult↗
PubMed1989

Thermosensitive determination of patency in lumboperitoneal shunts. Technical note.

Surface cooling and thermistor recording over shunt tubing was used in 23 studies of cerebrospinal fluid shunt patency in 19 patients with lumboperitoneal shunts and normal-pressure hydrocephalus. Shunt patency was shown by downward reflection of the recording trace similar to that obtained for ventriculoperitoneal shunts. Obstruction was demonstrated by a flat-line recording or an upward deflection.

Body Temperature↗
PubMed1989

[Peculiar computed tomographic images after intracranial use of microfibrillar collagen hemostat: report of three cases].

After the intracranial application of microfibrillar collagen hemostat (Avitene), CT revealed contrast enhancement suggestive of brain abscess or residual or recurrent tumor in three patients. The first case was a 22-year-old male with left ventricular oligodendroglioma. At operation Avitene was applied to the ventricular wall and incised frontal lobe. Two months after the operation CT revealed ring enhancement at the left frontal lobe and ventricular enlargement. Craniotomy was performed again. Histological examination, however, revealed no recurrent tumor but residual Avitene and granulation. The second case was a 57-year-old female with left parietal glioblastoma multiforme. At operation Avitene was applied to the tumor cavity. Two months after the operation CT showed ring enhancement and craniotomy was performed again. Histological examination revealed residual Avitene and necrotic tissue. Five months after the first operation, craniotomy was performed for the third time, because recurrence was suspected after a CT scan. Histological examination revealed recurrent tumor and residual Avitene. The third case was a 19-year-old male with left frontal astrocytoma. Two months after the operation when Avitene was used for hemostasis, marked ring enhancement was observed. Five months after the operation, however, enhancement in CT was weak. The CT findings in these patients were characterized by the abnormally long duration of enhancement (five months) and by enhancement more marked two to three months after the operation than immediately after it. Based on these findings brain abscess or residual or recurrent tumor rather than normal healing was more suspect as the cause of this phenomenon. Brain abscess was ruled out, because the peripheral leukocyte count, erythrocyte sedimentation rate, CRP, etc. were normal.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Induction of rhythmic jaw movements by stimulation of the mesencephalic reticular formation in the guinea pig.

This study was designed to investigate whether stimulation of the mesencephalic reticular formation (MRF) induces rhythmic jaw movements (RJMs) and, if it does so, to determine the RJM-inducing region in the MRF in ketamine-anesthetized guinea pigs. The results were as follows: (1) Repetitive electrical stimulation of the MRF at the level of the red nucleus induced rhythmic EMG bursts in the anterior digastric muscle (DIG). (2) The duration and cycle time of the rhythmic DIG EMG burst induced from the medial MRF were longer than those induced from the lateral MRF. (3) Repetitive MRF stimulation after paralysis still induced rhythmic multiple-unit activities in the anterior digastric motoneuron pool. (4) Neither precollicular decerebration nor cerebellectomy affected the MRF induction of RJMs. (5) Transverse hemisection at the rostral border of the pons abolished the RJMs induced from the contralateral, but not ipsilateral, MRF. Midline section of the midbrain abolished RJMs induced from the MRF on either side. (6) A lesion in the pontine pyramidal tract abolished the RJMs induced by stimulation of the ipsilateral cortical masticatory area (CMA), but not those induced from the contralateral MRF. (7) A unilateral lesion of the oral portion of the gigantocellular reticular nucleus, where the rhythm generator for the CMA-induced RJMs is located, abolished RJMs induced from not only the CMA, but also MRF on the contralateral side. (8) Microinjection of L-glutamate into the lateral, but not medial, MRF induced RJMs similar to those elicited by repetitive electrical stimulation of the same site.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

[Analysis of CSF flow through L-P shunt during changes in posture].

Two methods for percutaneous study of lumboperitoneal shunt patency are described. The first is an LP shuntography in which patency of the shunt can be assessed by the intraperitoneal spread of contrast medium injected intrathecally via the lumbar route. This method was performed in 27 hydrocephalic patients. The other is a thermosensitive determination technique, in which patency of the shunt can be assessed by definite temperature changes. In a patient with an LP shunt, flow of CSF, and hence patency of the shunt, are indicated by a downward deflection of the recording trace. Twenty-three trials of the thermosensitive determination of CSF shunt patency in LP shunts of 19 hydrocephalic cases were performed. We got five different types of recording traces by the thermosensitive method. A flat-line recording (two recordings) and an upward deflection (two recordings) showed complete occlusion. Operative findings and LP shuntography showed that four cases with a nearly flat line recording had a partial occlusion of the shunt. Patency of the shunt was confirmed by LP shuntography in all cases (12 recordings) with a gradual downward deflection. A steep downward deflection showed an acute excessive CSF drainage. An experimental study was carried out to perform a quantitative analysis of CSF flow in an LP shunt. Derived data suggested that the flow velocity was 10 ml/hr in a case with a nearly flat-line recording, 30 ml/hr in a case with a gradual downward deflection and 60 ml/hr in a case with a steep downward deflection.(ABSTRACT TRUNCATED AT 250 WORDS)

Cerebrospinal Fluid↗
PubMed1988

Subdural tension pneumocephalus following surgery for chronic subdural hematoma.

The computerized tomography (CT) findings were analyzed in five cases of subdural tension pneumocephalus following surgery for chronic subdural hematoma. They were compared with CT scans in 14 cases of asymptomatic subdural pneumocephalus. In this study, two new CT findings were identified that suggest increased tension of the subdural air. Subdural air separates and compresses the frontal lobes, creating a widened interhemispheric space between the tips of the frontal lobes that mimics the silhouette of Mt. Fuji. The presence of air between the frontal tips associated with massive air inclusion over the frontal lobes presumably indicates increased tension of the subdural air. The "Mt. Fuji sign" was seen in four of the five cases with subdural tension pneumocephalus. The other finding was the presence of multiple small air bubbles scattered through several cisterns ("air bubble sign"). It is postulated that these air bubbles enter the subarachnoid space through a tear in the arachnoid membrane caused by increased tension of air in the subdural space. This finding was seen in four cases with subdural tension pneumocephalus. These two CT findings are helpful in making a diagnosis of subdural tension pneumocephalus following surgery for chronic subdural hematoma.

Aged↗
PubMed1988

A new technique for percutaneous study of lumboperitoneal shunt patency. Technical note.

A new technique for percutaneous imaging of a one-piece lumboperitoneal shunt is described. Patency of the shunt can be assessed by the intraperitoneal spread of contrast medium which is injected intrathecally via the lumbar route. No special equipment or instrumentation is required other than a typical lumbar puncture tray and a general examination tilt table for fluoroscopy.

Cerebrospinal Fluid Shunts↗
PubMed1988

[Three-dimensional analysis of maxillary alveolar process in bilateral cleft lip and palate patients].

The collapsed maxillary alveolar arch in bilateral cleft lip and palate (BCLP) patients was quantitatively evaluated by three dimensional analysis. Materials were consisted of alveolar models taken from 15 Japanese boys (11 years old) with BCLP. The findings obtained were as follows: 1. Examination of the alveolar displacement in individual BCLP patients disclosed a marked tendency of inward and upward displacement of the lateral segments. On the other hand, premaxilla showed an upward displacement in the vertical dimension with a great deal of variation in the amount and direction of horizontal displacement. 2. Concerning the average amount of horizontal displacement, the premaxilla showed relatively little, but the lateral segment, especially the left one, showed a considerably large amount. In the vertical dimension, both the premaxilla and lateral segment were displaced markedly upward. 3. Patterns of collapsed alveolar arch in BCLP patients were classified according to the amount of horizontal displacement of the premaxilla into the following 4 types; type A (larger displacement towards the inside), type B (moderate or smaller displacement towards the inside), type C (moderate or smaller displacement towards the outside) and type D (larger displacement towards the outside). The order of prevalence of these 4 types was B,C,A,D in order. On the other hand, in the vertical dimension, the direction of displacement of the premaxilla was upward in all patients. 4. The anterior edge of the lateral segments showed the largest amount of displacement both in the horizontal and vertical dimensions. In a comparison of these results with those of Unilateral Cleft Lip and Palate (UCLP), the total amount of horizontal displacement of the maxillary alveolar process was larger in UCLP, while the vertical one was larger in BCLP. A remarkable difference between BCLP and UCLP was found in the displacement of the anterior region due to the premaxilla in BCLP.

Alveolar Process↗
PubMed1987

Cortically induced masticatory rhythm in masseter motoneurons after blocking inhibition by strychnine and tetanus toxin.

In the first series of experiments, we studied whether or not strychnine (STR)-resistant inhibition of masseter motoneurons (MASS . MNS) was involved in their rhythmical inhibition that occurs during masticatory activity, induced by repetitive stimulation of the cortical masticatory area (CMA) in the cat. After systemic STR injection, repetitive CMA stimulation induced rhythmically alternating activity in the masseteric and anterior digastric nerves with a shorter cycle time than before STR-administration. The short-latency IPSPS in the MASS . MNS evoked by single shocks applied to the CMA were abolished. In contrast, repetitive CMA stimulation still induced a rhythmical alternation of EPSPS and IPSPS in the MASS . MNS, although the IPSPS were significantly reduced in amplitude. In the second series, we attempted to abolish the STR-resistant component of the rhythmical IPSP with tetanus toxin (TT). This was injected into one superficial masseter muscle of the guinea pig. In the majority of animals, repetitive CMA stimulation induced a tonic EMG superimposed by rhythmical bursts in the TT-intoxicated masseter muscle. Repetitive CMA stimulation induced a rhythmical sequence of EPSPS and superimposed spikes in the MASS . MNS innervating the TT-intoxicated masseter muscle in paralyzed guinea pigs. It was concluded that: (1) the cortically-evoked short-latency inhibition of MASS . MNS is STR-sensitive, as is part of the rhythmical inhibition during CMA-induced mastication; and (2) rhythmical inhibition is not essential for the central generation of the rhythmical activity in the MASS . MNS.

Action Potentials↗