Search PubMed⌕ Search

Biomedical subjects

K Yamashiro

Publications and source records attributed to K Yamashiro.

At least 109 records · Page 6Linked to original sources
PubMed1991

Neurones with epileptiform discharge in the central nervous system and chronic pain. Experimental and clinical investigations.

Epileptiform discharge was recorded from neurons in the thalamic nuclei of chronic pain patients during stereotactic surgery. Hyperactive neurons showed regular firing of 3-5 trains of epileptic-like group discharges with a frequency of 4 to 5 Hz. As described by Lombard et al. (1979), we operated on the dorsal root unilaterally, sectioning C5 to Thl in male Wistar rats. One to three months after the operation, hyperactive neurons were examined in the contra-lateral thalamic nuclei (VP, zona incerta), and lemniscus medialis. The firing patterns and distribution of hyperactive neurons in these animals was very similar to those of humans. The hyperactive neuron was unaffected by electrical stimulation of the nucleus raphe dorsalis (NRD) and locus ceruleus (LC). Administration of phenytoin and diazepam reduced the firing. However, no effect was seen with valproic acid. During spreading depression of the sensorimotor cortex, a remarkable reduction was seen on the firing of thalamic hyperactive neurons. This suggested that hyperactive neurons of the thalamic nuclei received facilitory effects from the sensorimotor cortex with little influence from adrenergic or serotoenergic systems.

Animals↗
PubMed1990

Fluctuation in the concentrations of vanillylmandelic acid and homovanillic acid in mass screening for neuroblastoma.

Fluctuations in the amount of vanillylmandelic acid (VMA) and homovanillic acid (HVA) were studied in random urine samples from 13 infants with neuroblastoma. In patients with a small tumour, many samples contained amounts below the cut off values, suggesting that detection of a patient with neuroblastoma depended on mathematical probability. Using high performance liquid chromatography a patient with a tumour of about 10 g may well be overlooked, whereas a patient whose tumour weighs over 30 g would probably be detected. With qualitative screening, although more likely to miss a patient with low VMA excretion, a patient with a tumour weighing over 50 g would be detected. In a thorough hospital examination care should be exercised in interpreting borderline values of VMA and HVA; excretion information suggesting the existence of a tumour may aid localization by radiological imaging procedures.

Adrenal Gland Neoplasms↗
PubMed1990

Improvement in prognosis of neuroblastoma through mass population screening.

Since April 1981, the city of Sapporo, Japan, has conducted a mass screening program to measure urinary vanillylmandelic acid and homovanillylic acid using high-performance liquid chromatography. This program was expanded to the entire island of Hokkaido in October 1987. Mass screening proved beneficial, resulting in an increase in patients diagnosed with neuroblastoma under 1 year of age from 17% to 66%, an increase in stage I cases from 9% to 26%, an increase in stage III cases from 9% to 32%, and an increase in the tumor resectability rate from 15.1% to 58%. These improvements raised the 5-year survival rate for neuroblastoma from 23% to 66.7%. An additional study of these mass screening cases using Shimada's classification showed a wide range of histopathological distribution, and it demonstrated the usefulness of such a program in identifying the tumors most in need of early treatment.

Adrenal Gland Neoplasms↗
PubMed1990

Microstimulation for stereotactic neurosurgery.

840 microstimulations were done in 21 patients with movement disorders and chronic pain. Paresthesia was the most common response and occurred in 53.3% of cell responses, since the present study was performed mainly in the nucleus ventrocaudalis (Vc). Sensorimotor responses were noted in 8.3%, mainly from the Vc, but they were also noted from the nuclei intermedialis (Vim) and oralis posterior (Vop). Motor responses were noted in 3.6%, mainly from the Vim and Vop nuclei. Pain sensation was elicited in 3.8% and no response was seen in 22.6% of cells after stimulation.

Chronic Disease↗
PubMed1990

[A neuron-specific enolase (NSE) positive leiomyosarcoma].

A 40-year-old woman with multiple skin tumors was admitted to our hospital on September 5, 1989. Extensive studies by means of light and electron-microscopic examination and immunohistochemical analysis revealed a neuron-specific enolase (NSE) positive leiomyosarcoma. The level of her elevated serum NSE decreased after receiving her initial chemotherapy, but after the fourth session of chemotherapy, the NSE began to elevate again and she died on December 25, 1989. NSE appears to be a useful marker for determining if the neuronal and neuroendocrine cells are normal. This rare case, however, seems to demonstrate that abnormal, nonneuronal cells like a sarcoma also open metabolic pathways to synthesize NSE.

Adult↗
PubMed1990

[B-chronic lymphocytic leukemia/prolymphocytic leukemia (CLL/PL)--a case report].

A 48-year-old male was admitted to our hospital on April 20, 1989 because of general fatigue and abdominal fullness. Physical examination showed hepatomegaly, massive splenomegaly, and systemic lymphadenopathy. Hematological findings revealed WBC 73,000/microliters, RBC 289 x 10(4)/microliters, Hb 8.0g/dl, and platelet 9.1 x 10(4)/microliters. WBC differential count demonstrated a mixture of 63% matured small lymphocytes and 32% prolymphocytoid cells. Bone marrow aspiration was unsuccessful with a dry tap. Surface marker analysis of peripheral blood lymphoid cells disclosed that they were positive for anti-HLA-DR, CD 5, CD 19, CD 20, CD 21, CD 25, Sm-IgM, Sm-IgD, and Sm-K. He was diagnosed as B-CLL/PL, and treated with VEPA with partial remission. CLL/PL which was advocated by Melo in 1986 is regarded as a distinct clinical entity intermediate between CLL and PLL in clinical and laboratory features. Our case is interesting with regard to good response to combination chemotherapy, though most cases of CLL/PL have a resistance to standard chemotherapy.

Antigens, CD↗
PubMed1990

[A transitional cell carcinoma of the urinary bladder with a high level of serum CA 19-9--a case report].

Reported is the case of a 72 year-old man who was hospitalized because of abdominal pain and gross hematuria. A subsequent laboratory examinations revealed a high level of serum CA 19-9, and abdominal computed tomography showed a mass lesion behind the urinary bladder and multiple lymphadenopathy. Examination of the digestive organs revealed no abnormality, however cystoscopy showed a submucosal a tumor with a partly ruddy surface. Thus, a percutaneous needle biopsy and a transurethral biopsy were performed. The pathological findings indicated a transitional cell carcinoma of the urinary bladder, and ABC-peroxidase staining revealed the presence of CA 19-9 positive cells in a portion of the carcinomatous cells.

Aged↗
PubMed1989

Effect of midbrain raphe nucleus stimulation on somatosensory evoked potential in cat.

Experiments were carried out to clarify the effect of serotonin [5-hydroxytryptamine (5-HT)] upon the somatosensory evoked potential (SEP) elicited by superficial radial nerve stimulation in cat, and the following results were obtained: (i) in untreated (control) animals, a significant reduction occurred in amplitude of the SEP in response to conditioning stimulation of the dorsal raphe nucleus in the midbrain, within 100 ms of the interval between conditioning and test stimuli; (ii) in 5-HT depleted animals prepared by intraperitoneal injection of p-chlorophenylalanine (PCPA), the amplitude of SEP significantly increased in comparison with that of nontreated animals. Conditioning stimulation of the raphe nucleus in 5-HT depleted animals failed to cause any remarkable change in the SEP; (iii) the diminuation of the SEP by raphe nucleus conditioning reappeared following intraventricular administration of a large dose of 5-HT (200 micrograms) in the PCPA-treated animals. These results have demonstrated that the serotonergic system with its cell bodies located in the raphe nucleus of the midbrain has the function of reducing the amplitude of the SEP, thus suggesting that it acts as a suppressive control on the excitability of the cortex to sensory input.

Animals↗
PubMed1989

Evoked potentials from the human thalamus: correlation with microstimulation and single unit recording.

During stereotactic surgery, intrathalamic single unit recordings and summated evoked potentials (Th-SEP), evoked by percutaneous electrical median nerve stimulation and intrathalamic microstimulation, were done using the same microelectrode at the same site. Potentials evoked by natural and electrical stimulation were compared. The format of Th-SEP varied in anteroposterior, mediolateral and dorsoventral directions in the ventrocaudal nucleus (Vc). The positive response peak latency was shortest from the caudal part of Vc and longest from the anterior part of Vc.

Electric Stimulation↗
PubMed1989

[Prolymphocytic leukemia associated with serum hypo IgA].

A 69-year-old man was admitted for the evaluation of leukocytosis with atypical cells. Physical examination revealed marked hepatosplenomegaly. The peripheral blood demonstrated Hb 10.1 g/dl, platelet 13.6 x 10(4)/microliters, and WBC 14200/microliters with 76% lymphoid cells. Bone marrow showed 52.4% lymphoid cells. These cells had a nucleus which was relatively large with a coarse chromatin structure and one prominent nucleolus. Under electron microscopy, these cells had a narrow cytoplasm containing a few mitochondria with some microvilli. The surface of these cells was positive for Ia, B1, B2, C3R, and had markedly elevated IgM-K and IgD-K surface immunoglobulins. Levels of IgG, IgA and IgM were 1140 mg/dl, 53 mg/dl, and 198 mg/dl respectively. He was diagnosed as having B-PLL, and was treated with vincristine, cytarabine and prednisolone. Since B-CLL frequently in accompanied by reduced levels of one or several immunoglobulins, and the most significant is the decrease of IgA, it is speculated from our case that B-PLL is very similar to B-CLL in the abnormalities of B cell function.

Agammaglobulinemia↗
PubMed1988

Influence of the ipsilateral hemisphere upon somatosensory evoked potential in cats.

Somatosensory evoked potentials (SEPs) were recorded on the skull corresponding to the (left) SI area by (right) superficial radial nerve stimulation. Amongst the various components of the SEP, special attention was directed to the negative component (N15) with a latency of approximately 15 ms. Changes in this potential followed by conditioning stimulation of the ipsilateral (right) hemisphere were observed and the following results were obtained: (i) when conditioning stimuli were applied to the contralateral (left) superficial radial nerve, the ipsilateral (right) thalamic VPL nucleus and the ipsilateral (right) sensory cortex, the amplitude of N15 decreased to 65-80% of the control level at C-T intervals less than 100 ms and (ii) following functional elimination of the unilateral sensory cortex by KCl application, the amplitude of N15 recorded at the opposite side significantly increased. In this condition, the inhibitory effects of the ipsilateral thalamus and contralateral peripheral nerve disappeared. From these observations, ipsilateral homologous cortex may well have an inhibitory influence upon the near field potential (N15) of the SEP.

Animals↗
PubMed1988

Single-unit analysis of the human ventral thalamic nuclear group: somatosensory responses.

1. We have studied the functional and somatotopic properties of 531 single mechanoreceptive thalamic neurons in humans undergoing stereotactic surgery for the control of movement disorders and pain. The majority of these somatosensory cells had small receptive fields (RFs) and were activated in a reproducible manner by mechanical stimuli applied to the skin or deep tissues. These neurons, which we termed "lemniscal," could be further classified into those responding to stimulation of cutaneous (76% of lemniscal sensory cells) or deep (24%) structures. 2. The incidence of neurons having cutaneous or mucosal RFs in the perioral region, thumb, and fingers (66%) was much higher than that of neurons having RFs elsewhere on the body. Most of the deep cells were activated by movements of and/or mechanical stimuli delivered to muscles or tendons controlling the elbow, wrist, and fingers. 3. Sequences of cells spanning several millimeters in the parasagittal plane often exhibited overlapping RFs. However, RFs changed markedly for cells separated by the same distances in the mediolateral direction. This suggests that the cutaneous somatotopic representation of each region of the body is organized into relatively thin sheets of cells oriented in the parasagittal plane. 4. By comparing neuronal RFs in different parasagittal planes in thalamus of individual patients we have identified a mediolateral representation of body surface following the sequence from: intraoral structures, face, thumb through fifth finger to palm, with forearm and leg laterally. 5. Along many trajectories in the parasagittal plane the sequence of cells with overlapping RFs was interrupted by another sequence of cells with RFs corresponding to a different body region. The RFs of the intervening sequence characteristically represented body regions known to be located more medially in thalamus (see 3 above). These findings could be explained if the lamellae postulated above were laterally convex. 6. Cells responding to deep stimulation (deep cells) could be further classified into those responding to joint movement (63%), deep pressure (15%), or both (22%). Deep cells were found usually at the anterior-dorsal border and sometimes at the posterior border of the region containing cells responding to cutaneous stimuli. Although there was some overlap in the RFs, deep cells representing wrist were found medial to those representing elbow, and both of these were found medial to cells representing leg.(ABSTRACT TRUNCATED AT 400 WORDS)

Brain Mapping↗
PubMed1988

Methods for microstimulation and recording of single neurons and evoked potentials in the human central nervous system.

An apparatus and technique are described for microstimulation and recording of both slow wave and single neuron (single unit) activities during functional stereotaxic procedures. This method facilitates microstimulation and evoked potential and single unit analysis which, in combination, provide optimum definition of stereotaxic targets in the treatment of functional disorders of the human central nervous system.

Brain↗