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Biomedical subjects

N Oka

Publications and source records attributed to N Oka.

At least 109 records · Page 6Linked to original sources
PubMed1992

Changes in the cerebral vascular bed in experimental hydrocephalus: an angio-architectural and histological study.

The angio-architectural and histological changes of small cerebral blood vessels in experimental hydrocephalus were studied to assess the changes of the vascular bed in the cerebral mantle. Change of the microvasculature assessed from microcorrosion casts by scanning electron microscopy (SEM) and the histological changes shown by light and electron microscopy were compared before and after shunting for hydrocephalus. The changes of the rCBF were also evaluated by the hydrogen clearance method. In hydrocephalus, a reduction in the number and caliber of the capillaries was noted in both the white and gray matter in the SEM study, but the capillaries were preserved and changes were mild and nonspecific in the electron microscopic examination. Shunting resulted in the reversal of all these changes to normal along with recovery of the rCBF, which had decreased in hydrocephalus. These observations suggest that changes of the vascular bed participate in the alteration of cerebral mantle width in the hydrocephalic process, and that the changes of the microvasculature result not only from damage to the capillaries themselves but also from changes of the perivascular structures.

Animals↗
PubMed1992

Rapid axonal transport velocity is reduced in experimental ethylene oxide neuropathy.

Chronic exposure of rats to ethylene oxide (EO) causes distal axonal neuropathy of lumbosacral primary sensory neurons. To study the pathogenesis of this neuropathy, we measured rapid axonal transport in peripheral nerves. Rats were exposed for 6 h to 500 ppm EO in a chamber three times a wk for 15 wk. Rapid axonal transport and quantitative histological alterations of peripheral nerves were studied. After [35S]methionine injection into the dorsal root ganglion, the velocity of rapid anterograde axonal transport of radioisotope-labeled protein was measured. The velocity in the rats exposed to EO was 33% less than that in control rats exposed to filtered room air. However, histological differences were slight. Morphometric studies showed that in EO-exposed rats, only the distal portions of the sural nerve had significantly greater incidental degeneration of myelinated fibers than did controls. There were significantly fewer large myelinated fibers only in the distals peroneal nerve. Therefore, a decrease in the velocity of anterograde axonal transport, related to these slight histological abnormalities of the peripheral nerve, may play a causative role in the development of the distal axonal neuropathy owing to chronic EO exposure.

Animals↗
PubMed1992

Different protein kinase C isozymes could modulate bradykinin-induced extracellular calcium-dependent and -independent increases in osteoblast-like MC3T3-E1 cells.

Effects of protein kinase C (PKC) on bradykinin (BK)-induced intracellular calcium mobilization, consisting of rapid Ca2+ release from internal stores and a subsequent sustained Ca2+ inflow, were examined in Fura-2-loaded osteoblast-like MC3T3-E1 cells. The sustained Ca2+ inflow as inferred with Mn2+ quench method was blocked by Ni2+ and a receptor-operated Ca2+ channel blocker SK&F 96365, but not by nifedipine. The short-term pretreatment with phorbol 12-myristate 13-acetate (PMA), inhibited BK-stimulated Ca2+ inflow, and the prior treatment with PKC inhibitors, H-7 or staurosporine, enhanced the initial internal release and reversed the PMA effect. Moreover, 6 h pretreatment with PMA caused similar effect on the BK-induced inflow to that obtained with PKC inhibitors, whereas 24 h pretreatment was necessary to affect the internal release. On the other hand, the translocation and down-regulation of PKC isozymes were examined after PMA treatment of MC3T3-E1 cells by immunoblot analyses of PKCs with the isozyme-specific antibodies. 6 h treatment with PMA induced down-regulation of PKC beta, whereas longer treatment was needed for down-regulation of PKC alpha. Taken together, it was suggested that the BK-induced initial Ca2+ peak and the sustained Ca2+ inflow through the activation of a receptor-operated Ca2+ channel, are differentially regulated by PKC isozymes alpha and beta, respectively, in osteoblast-like MC3T3-E1 cells.

Animals↗
PubMed1992

Tubulomembranous lesions in p-bromophenylacetylurea neuropathy reflect local stasis of fast axonal transport: evidence from electron microscopic autoradiography.

The source of the membranous materials that accumulate in distal axons of rats intoxicated with p-bromophenylacetylurea (BPAU) was studied by electron microscopy. 35S-Methionine was injected into the ventral horn of the spinal cord at 2, 14, and 35 days after injection of BPAU. Three days later, samples of the deep peroneal nerves were obtained, and autoradiographs of thin cross sections were prepared. Organellar accumulations were absent from vehicle-treated control nerves and rare in the clinically latent period after administration of BPAU. In later stages of neuropathy, approximately 20% of the myelinated axons in any specific section were swollen and packed with tubules, membranes, and mitochondria. Numerous silver grains were located over the accumulated organelles, and the coincidence was statistically significant. The results indicate a sporadic local stasis of fast-transported proteins and provide a plausible explanation for axonal damage in BPAU neuropathy.

Animals↗
PubMed1992

[Adjuvant chemotherapy with MVP-CAB (methotrexate, vincristine, cisplatinum, cyclophosphamide, adriamycin and bleomycin) for epithelial tumors of the upper urinary tract].

Surgery plus adjuvant chemotherapy using MVP-CAB (Day 1; methotrexate 20 mg/m2, vincristine 0.6 mg/m2, cyclophosphamide 500 mg/m2, adriamycin 20 mg/m2, and bleomycin 30 mg, Day 2; cisplatinum 50 mg/m2) was conducted in 12 patients with epithelial tumors of the upper urinary tract who had unfavorable prognostic factors (progressive disease which was pT2 or more, or transitional cell carcinoma of grade 2 and 3). The MVP-CAB regimen was as follows: A total of 3 cycles were given either before or after surgery. MVP-CAB was given at 3- to 4-week intervals before surgery, or after surgery if the patient had macroscopic residual lesions. For the patients with micrometastases detected after radical surgery, MVP-CAB was given every 1 to 2 months. The median survival period of the 10 patients who underwent radical surgery was 17 months (5-59 months). The three-year survival rate of these 10 patients (Kaplan-Meier method) was 100% in grade 2 (5 patients), 100% in progressive cancer greater than pT3 (6), and 80% in grade 3 (5). In two patients, residual macroscopic lesions after surgery were confirmed. One of them initially responded to MVP-CAB but died of cancer 21 months later, while the other one did not respond and died of cancer 8 months later. Two renal pelvis cancer patients for whom radical surgery was considered impossible due to distant metastases showed remarkable tumor reduction after MVP-CAB administration (one showed CR for liver metastases and the other showed PR for lymph node metastases).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1992

[Kock-rectal bladder. Augmented and valved rectum].

Eight patients with total cysto-urethrectomy underwent an augmented and valved rectum (Kock), a type of continent urinary diversion. A satisfactory outcome was obtained in 6 patients. These 6 patients urinated 6 to 8 times a day (1-2 times during the night). The volume each time was 350-450 ml. Urinary incontinence occurred only 1-2 times a month when deeply asleep, and there were no patients whose daily life was restricted. However, there were 3 patients with urinary tract complications. In 2 of them, urinary diversion was required, and unilateral total ureteral obstruction was observed in the remaining patient. The reason for the complications appeared to be that stapling of the intussusception of the sigmoid colon was performed in 5 placements as described in the original method. Following the 4th patient, we were able to prevent any complication in the urinary tract by stapling of the intussusception in 3 places (at 12, 5 and 7 o'clock), and by suturing mucosa to mucosa of the rectum and intussusception in 6 places with polyglycolic acid suture, and further suturing serosa to serosa of the sigmoid colon and rectum in 4 places with silk suture.

Aged↗
PubMed1992

[Microsurgical autotransplantation of abdominal testis].

A 32-year-old man who had bilateral non-palpable testis underwent microsurgical orchidopexy of the right abdominal testis. Inferior epigastric vessels were used for the recipient vessels. Ischemic time during the operation was 40 minutes. Postoperative doppler readings revealed excellent blood flow to the testis, and HCG-stimulating test revealed good response. Now, 2 years after surgery, no sign of atrophy is found.

Adult↗
PubMed1992

[Adjuvant chemotherapy (MVP-CAB; methotrexate, vincristine, cisplatinum, cyclophosphamide, adriamycin, and bleomycin) for bladder cancer].

Twenty-three patients with bladder cancer (TCC; 18 patients, SCC; 5 patients) were treated with adjuvant chemotherapy (day 1: methotrexate 20 mg/m2, vincristine 0.6 mg/m2, cyclophosphamide 500 mg/m2, adriamycin 20 mg/m2, bleomycin 30 mg, day 2: cisplatinum 50 mg/m2; MVP-CAB). A total of 3 cycles of MVP-CAB were given as preoperative or postoperative therapy. The following results were obtained. Group 1 (purpose to preserve the bladder, preoperative MVP-CAB): Four of 7 patients achieved a partial response. It was possible to perform bladder preservation surgery in 3 of these 4 patients. All 3 patients had pedunculated, solitary tumors, and there was no carcinoma in situ. Group 2 (purpose to improve the prognosis; preoperative MVP-CAB): Hydronephrosis did not resolve in the 4 patients with this complication. They received total cystectomy, and 2 patients died of cancer 23 months later. Group 3 (purpose to improve the prognosis; postoperative MVP-CAB): Ten of 12 patients (total cystectomy; 10 patients, partial cystectomy; 2 patients) survived disease-free for an average of 17 months (5-44 months), 1 patient developed recurrence 12 months later, and 1 patient died of cancer 6 months later. The 1-year survival rate in Group 3 was 86% for TCC, 100% for SCC, 80% for grade 3 TCC, and 89% for pT2 or more advanced cancer.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1992

[Migrant sensory neuritis--electrophysiological and pathological study].

Migrant sensory neuritis, which was first proposed by Wartenberg, is very uncommon and only a few case reports have ever been published. We described one case of migrant sensory neuritis and discussed the pathogenesis of this disease. A 44-year-old man noticed numbness in the lateral aspect of the dorsum of the left foot in February 1985. Physically, there was hypoesthesia in the region of left sural nerve with positive Tinel's sign. During the next 4 years, pain, tingling sensation or hypoesthesia appeared in the regions of the right superficial radial nerve, right axillary nerve, left intercostal nerve, left lateral plantar nerve, digital nerve of the right second digit, left saphenous nerve, right superficial peroneal nerve, left superficial radial nerve, bilateral ulnar nerves and bilateral median antebrachial cutaneous nerves one after another in a migrating fashion. Tinel's sign was also positive at the right superficial radial nerve. In some occasions, decreased deep tendon reflexes were observed, but there had been no muscle weakness. Some nerves showed complete recovery, but others showed persistent involvement. Some nerves were affected repeatedly. Laboratory examination failed to clarify underlying disease except for mild liver dysfunction. Electrophysiological study showed reduced amplitude of the sensory nerve action potential (SNAP) of right sural nerve, left ulnar nerve, right superficial radial nerve and digital branch of right median nerve with preserved sensory nerve conduction velocity. SNAP of left sural nerve was absent. These findings mean the cause of the sensory disturbance is axonal degeneration rather than segmental demyelination. There were no abnormalities in motor nerve conduction study.(ABSTRACT TRUNCATED AT 250 WORDS)

Action Potentials↗
PubMed1992

[Multifocal axonal motor neuropathy associated with anti-ganglioside antibodies].

We report a patient with asymmetrical patchy weakness of the limbs, and with autoantibodies against gangliosides GM1, GD1b, asialo GM1. Although electrophysiological studies did not reveal conduction block, treatment with prednisolone resulted in clinical improvement. A 52-year-old man was admitted to Kyoto University Hospital, because of gait disturbance. Neurological examination revealed a patchy distribution of weakness in the limbs. Deep tendon reflex was normal at the right knee, and was depressed at the right biceps. Other deep tendon reflexes were absent. There was a slight decrease in vibratory sensation in the distal portions of the lower extremities. Routine laboratory studies, heavy metal screen, vitamin, cryoglobulin, coproporphyrin and delta-amino levulinic acid in urine, and the protein value of the cerebrospinal fluid were normal. Head and neck MRI, and myelography were normal. Immunofixation electrophoresis showed IgM lambda M-protein in serum. Thin-layer chromatography with immunostaining showed his serum IgM reacted with GM1, GD1b, and asialo GM1. ELISA (Enzyme Linked Immunosorbent Assay) demonstrated high titers of anti GM1, GD1b and low titer of anti asialo GM1. Motor conduction studies showed no demonstrable conduction block, normal conduction velocities and the low amplitudes of CMAP. Sensory conduction studies showed no abnormalities except for slightly decreased amplitude of SNAP in sural nerve. Electromyography showed active denervation in extensor digitorum communis muscle, tibialis anterior muscle and left biceps brachii muscle. Muscle biopsy specimen revealed large and small group atrophy and there was perivascular mononuclear infiltration at one point.(ABSTRACT TRUNCATED AT 250 WORDS)

Autoantibodies↗
PubMed1992

[The clinical effect of cisplatin and 5-FU infusion in oral cancer].

The combination chemotherapy of cisplatin and 5-fluorouracil (5-FU) is more effective than monotherapy of either drug in the head and neck cancer. In 1982, Kish reported that CF-therapy, the combination of cisplatin and 5-FU, had a high curative rate (about 82%). CF-therapy was utilized in 9 patients with carcinoma of the oral region from March, 1987 to September, 1990 in our hospital. The patients' ages ranged from 23 to 74 years old with an average of 55. All tumor were squamous cell carcinoma. There were 2 cases in stage II, 4 cases in stage III and 3 cases in stage IV. Two patients treated with only CF-therapy and the other patients treated with radiotherapy and operation in addition to CF-therapy. Our regimen is cisplatin 80-100 mg i.v. or i.a. in day 1 and 5-FU 250 mg i.a. or 5-FU 750 mg i.v. in day 2-6. The therapeutic results showed a 78% response rate to the therapy with 4 cases of CR (complete response), 3 cases of PR (partial response), 1 case of MR (minor response) and 1 case of PD (progressive disease). Side effects of cisplatin plus 5-FU (eg. nausea and vomiting) were so severe that the treatment had to the stopped in many patients. The method we have reported here was evaluated, and it is concluded that this CF-therapy is very effective as a first treatment of oral cancer.

Adult↗
PubMed1992

[Clinical use of serum erythropoietin determination by the recombigen EPO RIA kit].

Serum erythropoietin (EPO) levels were determined by the recombigen EPO RIA kit (DPC) in normal subjects and patients with renal dysfunction, diabetes mellitus, hypothyroidism and a variety of hematological disorders. Mean (+/- SD) serum EPO levels were 18.6 +/- 5.6 mU/ml in 180 normal subjects and no sex difference was obtained. Serum EPO levels in older subjects were slightly greater than those in younger subjects. There was a negative correlation between serum EPO levels and Ht values in anemic patients with normal renal function, whereas serum EPO levels were within the normal range in anemic patients with renal disorders, suggesting that serum EPO levels were relatively low in patients with chronic renal failure. Serum EPO levels were rather increased in patients with diabetes mellitus and hypothyroidism. High serum EPO levels were obtained in patients with a variety of hematological disorders such as acute leukemia, multiple myeloma, myelodysplasia syndrome, aplastic anemia and pure red cell aplasia. In a patient with pure red cell aplasia treated with glucocorticoids, serum EPO levels were lowered before anemia was recovered and reticulocytes were increased. These findings indicate that measurement of serum EPO levels are useful for not only differential diagnosis of anemia but also clinical evaluation of the treatment.

Adult↗
PubMed1991

[Incidence of abnormal thyroid function in patients with low titers of thyroid microsomal antibodies].

The incidence of abnormal thyroid function related to autoimmune disorders was examined in a district of Shimane Prefecture in 1988. Thyroid microsomal antibodies (MCPA) in sera were measured in a general population of 1,646, including 678 males and 968 females, aged 57.8 +/- 14.8 (mean +/- SD) yr. MCPA titer was defined as high (less than 1:128), low (1:16, 1:32, 1:64) or negative (less than 1:16) according to the highest dilution of test serum capable of agglutinating gelatin particles coated with the appropriate antigen. Test of MCPA revealed high titers in 141 subjects (group A), low in 43 subjects (group B) and negative in 1,462 (group C). Twenty-four patients with overt thyroid disorders were found in groups A and B: five with Graves' disease, two with Hashimoto's thyroiditis and 15 with goiter in group A, and two with goiter in group B. In the remaining 119 subjects in group A and 41 subjects in group B, serum free T4 (FT4) and TSH levels were measured. According to abnormalities in the levels of serum FT4 and/or TSH, their thyroid function was divided into the following 3 subgroups: 1) hyperthyroid (FT4 greater than 2.0 ng/dl, TSH less than 0.4 mu U/ml), 2) latent hypothyroid (0.8 less than FT4 less than 2.0 ng/dl, TSH greater than 5.0 mu U/ml) and 3) hypothyroid (FT4 less than 0.8 ng/dl, TSH greater than 5.0 mu U/ml). The hyperthyroid group consisted of two patients in group A and one in group B. Ten latent hypothyroid patients were found in group A and two in group B. Hypothyroidism was found in four patients in group A. The incidence of abnormal thyroid function was not different between group A (16 out of 119, 13.4%) and group B (three out of 41, 7.3%). Graves' disease and primary myxedema were found in one patient each in group B; these patients had no subjective symptoms but showed low titers of MCPA. These findings suggest that not only high titers of MCPA but also low titers of MCPA are closely related to abnormal thyroid function.

Adult↗
PubMed1991

Respiratory outcome in extremely premature infants following ketamine anaesthesia.

Premature infants are prone to develop postoperative apnoea. The purpose of the present study was to determine if risk factors could be identified to predict which patients would require postoperative tracheal intubation and lung ventilation. Twenty-five extremely premature infants (birth weight: 811 +/- 242 g (mean +/- SD) and operation weight: 1585 +/- 394 g) needing cryotherapy for retinopathy were studied. After surgery the tracheas were extubated if there was no prolonged apnoea, SaO2 greater than 85%, and heart rate greater than 120 bpm. In eight, tracheal extubation in the operating room was unsuccessful. Using multivariate discriminant analysis, four risk factors correlated with the need for pulmonary ventilation-gestational duration, birth weight, postconceptional age, and preoperative aminophylline treatment for seven days. A scoring system using these factors successfully predicted the need for a tracheal tube after surgery in 92% of patients. It is concluded that the system may be clinically useful in the perioperative care of low-birth-weight infants as it identifies important variables for evaluating postoperative prolonged apnoea.

Age Factors↗
PubMed1991

Preparation of enzyme-conjugated DNA probe and application to the universal probe system.

A general procedure for the cross-linking of enzyme to DNA has been developed for use as a nonradioactive probe. In this method, DNA is transaminated with diaminopropane to introduce primary amino groups into the cytosine residues. Then the amino groups are converted to thiol groups using a heterobifunctional cross-linker. The thiolated DNA is conjugated with the maleimide-introduced enzyme. With this method, alkaline phosphatase was cross-linked to a single-stranded DNA (sspUCRf1). The conjugate was able to detect 5 pg of target DNA (pUCf1 plasmid, 3.2 kbp) fixed onto the nitrocellulose membrane, using a colorimetric assay. The enzyme-conjugated DNA was applied to "the universal probe system," which consisted of two single-stranded DNA probes (a primary probe and a labeled secondary probe). Using alkaline phosphatase-conjugated sspUCRf1 DNA as the secondary probe, the c-myc gene and HBV DNA were detected effectively on Southern and dot-blot hybridization.

Alkaline Phosphatase↗
PubMed1991

Histomorphometric study of trabecular bone remodeling during condylar process fracture healing in the growing period: experimental study.

Trabecular bone remodeling during condylar fracture healing in the growing period was analyzed by histomorphometry with a synchronous system. Data from the study showed displacement of the fractured condyle was compensated by the changes in remodeling ascribed to the pubertal spurt of growth, and that such remodeling still continued even after clinical healing. The regional acceleratory phenomenon, evolved to potentiate tissue healing, was observed 1 week after induction of the fracture. Mesenchymal cells were presumably modulated into chondroblasts that promoted endochondral ossification. It was concluded that trabecular bone remodeling plays an important role in healing of condylar fractures during the growth period.

Animals↗
PubMed1991

Kabuki make-up syndrome (Niikawa-Kuroki syndrome) with cleft lip and palate.

Kabuki make-up syndrome (Niikawa-Kuroki syndrome), recognized in Japan in 1981, is characterized by mental and growth retardation with specific craniofacial malformation such as lower palpebral eversion and depressed nasal tip. In this paper we describe a case associated with cleft lip and palate. Attention should be paid by maxillofacial surgeons to this syndrome, since 41% of the cases have been associated with cleft lip and palate (Niikawa et al., 1988; Tonoki and Niikawa, 1988).

Cleft Lip↗