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Biomedical subjects

N Kohara

Publications and source records attributed to N Kohara.

At least 55 records · Page 3Linked to original sources
PubMed1995

Tonic vibration reflex and muscle afferent block in writer's cramp.

Patients with focal dystonia take advantage of certain cutaneous or proprioceptive sensory inputs to alleviate their symptoms ("sensory trick"). We examined the effects of increasing muscle spindle activity by the tonic vibration reflex maneuver and decreasing it by intramuscular injection of lidocaine. The vibration was applied to the palm or the tendon of forearm muscles in 15 patients with writer's cramp and 15 age-matched normal subjects. In 11 patients, the vibration induced dystonic postures or movements typical of those seen during writing. Normal subjects showed either no response to the vibration or a gradually developing tonic vibration reflex only in the wrist and finger flexors, which produced visible movements with a significantly longer latency (12.5 +/- 6.7 seconds [mean +/- standard deviation]) than what was observed in the patients (2.7 +/- 2.5 seconds, p < 0.0001). Local injection of lidocaine (0.5%, 5-40 ml/muscle) attenuated the tendon reflex with relatively little effect on the M response. Injection into muscles with increased activity produced marked reduction of dystonic movements and significant clinical improvement in 13 patients, whereas injection into the other muscles had no effect. The clinical benefit lasted for 1 to 24 hours after injection. In 13 patients who had additional injections of 10% ethanol, which blocks sodium channels for a longer period than does lidocaine, the duration of action was prolonged to 5 to 21 days. These findings suggest that muscles causing dystonic movements have abnormal sensitivities to vibration at rest and that muscle afferents may play a pivotal role in producing dystonic movements.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

Effective treatment of liver metastases from colon cancer with a combination of gamma-interferon and cisplatin chemotherapy: report of a case.

We report herein the case of a 63-year-old man with cancer of the sigmoid colon and metastatic nodules in the liver who was effectively treated with a combination of cisplatin regional chemotherapy, given through the hepatic artery, in conjunction with a 3-week course of intravenous gamma-interferon (INF-gamma), following palliative sigmoidectomy and dissection of the regional lymph nodes. This was followed-up by a 3-month course of oral 5-fluorouracil. Hepatic imaging performed 6 months postoperatively showed no masses in the right hepatic lobe and an apparent decrease in the size of the tumor in the left lobe. A second-look operation with resection performed at this time confirmed the efficacy of the chemotherapy. The patient survived in excess of 30 months following his initial surgery before succumbing to hepatic failure.

Adenocarcinoma↗
PubMed1995

Expression of epidermal growth factor receptor messenger RNA in human colorectal carcinomas assessed by non-radioactive in-situ hybridization.

No consensus as to the involvement of the epidermal growth factor receptor (EGF-R) in colorectal carcinomas has yet been attained, although they are assumed to play a role in the metastasis to lymph nodes and recurrence of breast carcinoma and bladder carcinoma invasion. Knowing that Dukes' classification of colorectal carcinoma is closely related to prognosis, we examined whether there is a correlation between Dukes' classification and the expression of EGF-R in colorectal carcinoma. If there is a positive correlation, the involvement of EGF-R in the processes may be assumed and the expression of EGF-R may be used as a marker of their prognosis. To this end, the expression of EGF-R mRNA and protein by non-radioactive in-situ hybridization and immunohistochemistry, respectively, were determined on histological preparations of formalin-fixed paraffin-embedded colorectal surgical specimens. In 30 cases of colorectal carcinoma examined, mRNA and/or protein was detected in 33% (two of six) of Dukes' A, in 40% (four of 10) of Dukes' B, in 36% (four of 11) of Dukes' C, in 33% (one of three) of Dukes' D and in 0% of normal colon epithelial cells. Thus, there was no positive correlation between the Dukes' classification and the expression of EGF-R. It is concluded that the expression of EGF-R in colorectal carcinoma is not a promising marker of prognosis. However, the role of EGF-R in EGF-R positive tumours remains to be examined.

Aged↗
PubMed1995

Physiological study of cervical dystonia. Task-specific abnormality in contingent negative variation.

To investigate the pathophysiology of dystonia, we recorded contingent negative variation (CNV) in 12 patients with cervical dystonia and in 12 age-matched normal subjects. In a simple reaction time paradigm, the subjects were given a pair of a warning stimulus and a subsequent stimulus that triggered head rotation to either side or extension of the fingers. In normal subjects, CNVs for head rotation were not affected by neck muscle pre-activation simulating torticollis, and were always symmetrical with equally high amplitudes over the frontal and central leads. By contrast, CNVs for finger movement had the maximum over the central lead and showed a characteristic distribution; those for the right finger movement had the left hemisphere dominance, whereas those for the left finger movement had similar amplitudes over both hemispheres. In patients with rotatory torticollis (rotatocollis), the components of CNVs for head rotation were markedly attenuated in all the leads, except for the initial negative deflection (orienting response). As a whole, cervical dystonia patients had significantly lower amplitudes of late CNVs for head rotation than normal subjects (P < 0.001), whereas late CNV amplitudes in finger extension did not differ in the two groups. Their reaction times for head rotation were similar, but durations of EMG activities were prolonged in the patients because of co-contractions of the antagonists. The task-specific CNV amplitude loss is therefore not explained by reaction times or by the abnormal neck muscle activities prior to the movement, but it reflects a failure of neural activities preparing for a phasic neck movement, resulting in co-contraction of the agonists and the antagonist. Dystonia may be associated with defective retrieval or retaining of specific motor programmes or subroutines in response to sensory stimuli.

Adult↗
PubMed1995

Comparison of therapeutic efficacies of type A and F botulinum toxins for blepharospasm: a double-blind, controlled study.

Type F botulinum toxin can be used for treating patients with dystonia who become refractory to type A toxin injection due to antibody development. We compared the therapeutic efficacy of type F botulinum toxin to that of type A toxin in a self-controlled, double-blind clinical trial. In nine patients with blepharospasm, we injected type A toxin on one side and the same units of type F toxin on the other side. Although the onset of clinical effect, maximal benefit, and adverse reactions were similar between type A and F toxins, the duration of the clinical effect was significantly shorter on the side injected with type F toxin. Although type F toxin proved its promise as an alternative to type A toxin, its usefulness is limited by the shorter duration of action.

Aged↗
PubMed1995

[Potassium channel dysfunction at the lesion site in multifocal motor neuropathy as revealed by threshold electrotonus].

Multifocal motor neuropathy presents as a treatable muscular atrophy and is characterized by persistent conduction block and fasciculations or myokymia. Although the pathological findings at the lesion site revealed perivascular demyelination with little evidence of remyelination, the mechanism of conduction block is still unknown. We explored the threshold electrotonus, which registers membrane potential changes through threshold variation, at the lesion site. The findings were consistent with focal potassium channel dysfunction, with some evidence of depolarization block. The disrupted blood-nerve barrier and lack of Schwann cell-mediated extracellular potassium regulation may predispose the membrane depolarization, thereby accounting for the conduction block and fasciculations. Sensory nerve fibers are known to have more inward rectifiers, which take up the extracellular potassium, than motor fibers, and this may explain the sparing of these fibers.

Humans↗
PubMed1994

Anti-GM1 antibodies and impaired blood-nerve barrier may interfere with remyelination in multifocal motor neuropathy.

Multifocal motor neuropathy has pure motor manifestation and nonremittent clinical courses. Antiganglioside antibodies, though variable in titers, are characteristically elevated in the majority of these patient. In our cases, pathological findings at the site of conduction block suggested impaired remyelination and disruption of blood-nerve barrier. These findings lead us to postulate that antibodies toward gangliosides or toward unknown antigens containing gangliosides initiate motor-specific demyelination. The lesion, once produced, may persist as a result of impaired remyelination caused by disrupted blood-nerve barrier. The antibodies bound to denuded axons may also interfere with a remyelinative process. If so, antibodies may not always be circulating, thus accounting for variable levels of titers.

Antibodies↗
PubMed1994

Cortical reflex negative myoclonus.

Three patients with progressive myoclonic epilepsy (PME), two of them clinically manifesting only negative myoclonus and the other manifesting both positive and negative myoclonus, were electrophysiologically investigated, and compared with two other patients with PME presenting with only positive myoclonus. Electric stimulation of the median nerve during sustained active wrist extension in the three patients with negative myoclonus often elicited a short lapse of the posture in the stimulated hand associated with a silent period in the muscle discharge with or without being preceded by an abrupt increase in the muscle discharge (C reflex). The occurrence of the stimulus-induced silent period was significantly correlated with that of the giant somatosensory evoked potentials (SEPs), and in two patients the silent period was elicited also in the opposite (non-stimulated) hand when the giant SEP was recorded at the hemisphere ipsilateral to the stimulus as well. In one patient, the duration of the silent period was positively correlated with the amplitude of the cortical SEP. Furthermore, the duration of the induced silent period was closely related to the recovery function of SEP in each individual case. In contrast, in the two patients manifesting only positive myoclonus, the silent period was not elicited by the peripheral stimulation, and the somatosensory cortex was hyperexcitable immediately after the peripheral stimulus. Thus, this stimulus-sensitive negative myoclonus is mediated by a transcortical reflex mechanism, and corresponds to the negative form of the cortical reflex myoclonus ('cortical reflex negative myoclonus').

Adult↗
PubMed1994

Expression of Kirsten-ras p21 in gastric cancer correlates with tumor progression and is prognostic.

The purpose of this study was to determine the correlation between expression of ras oncoproteins and the tumor stage or outcome of patients with gastric carcinoma. After the specificity of each anti-ras monoclonal antibody was confirmed by protein immunoblot analysis, immunohistochemical assays for a common-ras antigen present in N-, Harvey- and Kirsten (K)-ras oncoproteins, as well as for K-ras specific antigen, were performed on paraffin-embedded carcinoma tissue from 110 patients who underwent curative resection. By Western blot analysis, there was more p21 in fresh cancer specimens than in normal specimens. K-ras expression distinguished advanced from early gastric carcinoma and correlated with depth of cancer invasion. Among the 110 patients, survival rates of those with carcinomas positive for the common-ras or K-ras antigens were significantly lower than of those with antigen-negative carcinomas (p < 0.05). In a multivariate analysis, nodal involvement (p = 0.002), serosal invasion (p = 0.012) and K-ras p21 expression (p = 0.044) were independently predictive of the recurrence. These results suggest that K-ras p21 is a useful marker of tumor progression and poor prognosis after curative resection.

Aged↗
PubMed1994

Transcranial stimulation of the leg area of the motor cortex in humans.

We used transcranial magnetic stimulation on nine normal volunteers to establish an effective way to stimulate the leg area of the motor cortex. Three types of coils: a large figure-eight coil, small figure-eight coil, and a round coil were used. Surface electromyographic activities were recorded from the left tibialis anterior muscle, and the latencies and amplitudes compared with those obtained by anodal electrical stimulation. The most stable responses were obtained when the large figure-eight coil was centered over the vertex and backward current was run through it or when the round coil was centered two to three centimeters anterior to the vertex with left-flowing current in it at the posterior widening. The latencies obtained under these stimulation conditions were the same as those obtained by electrical stimulation. We conclude that direct activation of the pyramidal cells occurs in the leg area of the motor cortex in all forms of magnetic and electrical stimulation.

Electric Stimulation↗
PubMed1994

erbB-2 expression in well-differentiated adenocarcinoma of the stomach predicts shorter survival after curative resection.

BACKGROUND: Correlation between erbB-2 expression, histologic type of gastric carcinoma, and survival after curative resection was evaluated. METHODS: Paraffin-embedded specimens from 120 patients who underwent curative resection of gastric carcinoma were analyzed immunohistochemically for the expression of erbB-2. RESULTS: Enhanced erbB-2 expression correlated with tumor stage and depth of invasion. Well-differentiated adenocarcinomas had a higher incidence of erbB-2 expression than did poorly differentiated carcinomas. Survival rates of 33 patients with erbB-2-positive carcinomas were significantly lower than those of 87 with erbB-2-negative carcinomas (p < 0.001). Survival rates of patients with well-differentiated adenocarcinomas that were erbB-2 positive were significantly lower than those that were erbB-2 negative (p < 0.001). However, the presence of erbB-2 was not associated with altered survival in 46 patients with poorly differentiated carcinomas. Multivariate analysis of all 120 patients revealed that independent predictors of recurrent disease include nodal involvement (p = 0.003) and erbB-2 expression (p = 0.0051). CONCLUSIONS: Our results suggest that erbB-2 expression is a new marker associated with poor prognosis in well-differentiated gastric adenocarcinomas.

Adenocarcinoma↗
PubMed1994

Expression of p53 protein in gastric carcinomas is not independently prognostic.

BACKGROUND: Biologic significance of p53 protein expression in gastric carcinomas is unclear. The relationship between p53 expression and survival after curative operations for gastric carcinoma was evaluated. METHODS: Paraffin-embedded specimens from 135 patients who underwent curative resection of gastric carcinoma were analyzed immunohistochemically for p53 expression. RESULTS: Immunoreactivity of p53 was found in 37 of 135 gastric tumors. Six of 48 early gastric carcinomas expressed focally scattered p53. Pattern of p53 expression in the majority of advanced carcinomas was diffuse. In univariate analyses a significant relationship with survival was found for tumor size (p < 0.01), depth of invasion (p < 0.01), nodal involvement (p < 0.01), and p53 expression (p < 0.01). Significant relationships were found between p53 expression and nodal involvement (p < 0.01) and depth of invasion (p < 0.01). A multivariate analysis revealed that the independent predictors of recurrence were nodal involvement (p = 0.009) and depth of invasion (p = 0.009). In a logistic multiple regression analysis p53 expression was not independently related to the parameters, which suggests an aggressive tumor. CONCLUSIONS: Our results suggest that p53 expression did not correlate with the aggressiveness of gastric carcinomas and failed to be an independent predictor of outcome.

Aged↗
PubMed1993

Comparison of recording characteristics of monopolar and concentric needle electrodes.

Although both monopolar and concentric needle electrodes (MNE and CNE) are widely used in clinical EMG examinations, relatively little attention has been paid to the different recording characteristics of these electrodes. We compared motor unit potentials (MUPs) recorded with MNE and CNE and confirmed that larger MUP pick-up fields and amplitudes are recorded with MNE than with CNE but found no differences in duration or the number of phases. To determine the cause of these differences, we analyzed fibrillation potentials (FPs) recorded with MNE and CNE in patients with peripheral nerve injury. The FPs recorded had similar wave forms and amplitudes. The pick-up field for the FPs, however, was about 2 times larger for MNE than for CNE. We conclude that the differences of the recording characteristics of MNE and CNE for MUPs mainly are produced by their different pick-up fields.

Adult↗
PubMed1993

Vibration-evoked sensory nerve action potentials derived from Pacinian corpuscles.

To evaluate sensory response to natural stimuli, we developed a method to record sensory nerve action potentials evoked by high-frequency vibratory stimulation. Trains of 250 Hz sinusoidal indentations with a duration of 100 msec were applied to the finger tip at a rate of 3 Hz. The responses were obtained with surface electrodes placed over the median and ulnar nerves at the wrist. Averaged wave forms consisted of two components: an initial diphasic or triphasic potential and the following low amplitude trains of discharges phase-locked to vibratory stimuli. Anesthesia of the skin at the stimulation site or tourniquet-induced ischemia of the limb eventually diminished both components. Neither of them therefore represented artifacts from electrode movement or electromagnetic field intrinsic to the stimulator. Various kinds of mechanoreceptors may contribute to the first component. Pacinian corpuscles probably give rise to the second component as the only skin receptors that can respond to high-frequency vibratory stimuli of 250 Hz. This method helps examine neural coding of the receptor and the peripheral nerve fiber mediating vibration sense.

Action Potentials↗
PubMed1993

[Surgical treatment of recurrent thyroid carcinoma after primary resection].

Twenty-six patients who underwent the second operation for recurrent thyroid carcinoma were reviewed. 1) Three surgical interventions; dissection of local lymph nodes, modified neck dissection and extended neck dissection, for the patients with recurrent thyroid carcinoma were performed. Among these patients, recurrence of thyroid carcinoma occurred again in 14 (74%) of 19 patients with dissection of local lymph nodes, 15 (63%) of 24 with modified neck dissection, 2 (22%) of 9 with extended neck dissection. Patients with extended neck dissection had significantly less local recurrence than those with other procedures (p < 0.05). 2) Lymph node recurrence on the resected area occurred in 11 (73%) of 14 patients with dissection of local lymph nodes. Ten (67%) of 15 patients with modified neck dissection had recurrence beyond the dissected area. 3) In well differentiated carcinoma, there was recurrence in 5 (62%) of 8 patients with dissection of local lymph nodes, and in 4 (31%) of 13 with modified neck dissection. In contrast, in poorly differentiated carcinoma, we found recurrence in 8 (89%) of 9, and 10 (100%) of 10, respectively. However, in only one (20%) patient with extended neck dissection, recurrence occurred. We conclude that extended neck dissection should be the procedure of choice in patients with recurrent thyroid cancer whenever feasible.

Aged↗
PubMed1993

[The efficacy of external high frequency oscillation: experience in a quadriplegic patient with alveolar hypoventilation].

External high frequency oscillation (EHFO) around a negative pressure using a thoracoabdominal chamber without an artificial airway has been shown to be an effective form of ventilation in a quadriplegic patient. The patient was an 18 year old male, suffering from high-level cervical cord tumor (lipoma). His respiratory distress was severe, respiration was diaphragmatic only. Because of acute respiratory insufficiency, he was intubated and put on IPPV. Attempts at weaning were not thought to be feasible. Then the Hayek Oscillator was applied with a frequency of 120. After 5 days on the Hayek Oscillator, he was extubated. EHFO was associated with a significant increase in PaO2 and VA, and a significant decrease in PaCO2. It is remarkable that the patient expelled sputum whenever he was connected to the Hayek Oscillator, far beyond that achievable by physiotherapy. EHFO avoids the need for endotracheal intubation, thus reducing the hazards of mechanical ventilation attributable to intubation. We conclude that EHFO produces gas exchange significantly and that this technique may have potential clinical application.

Adolescent↗
PubMed1992

Immunohistochemical characteristics of adenosquamous carcinoma of the pancreas.

Six patients with adenosquamous carcinoma (ASqC) of the pancreas were studied clinicopathologically and immunohistochemically. In five of six ASqC tumors, both malignant squamous and glandular elements were reactive with CA 19-9, ST 439, and keratin antibodies. In contrast, a portion of the glandular element in the remaining one ASqC was reactive with CA 19-9 and ST 439 antibodies, but that of the squamous cell carcinoma (SqCC) was not reactive. However, SqCC of this tumor was intensely reactive with keratin antibody. These immunohistochemical results suggest that the histogenesis in one ASqC tumor was different from that of the other 5 ASqCs, and that this tumor may be a collision tumor rather than transformation to SqCC from adenocarcinoma, which is a very rare pattern of histogenesis in ASqC. The patients with ASqC of the pancreas showed shorter survivals following operations because of systemic metastasis including liver metastasis.

Adenocarcinoma↗