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Biomedical subjects

Y Oka

Publications and source records attributed to Y Oka.

At least 415 records · Page 23Linked to original sources
PubMed1990

[Experimental study on tension and stretching to peripheral nerve].

As to the suturing large peripheral nerve defects under tension, several questions have not yet been answered. How long is the critical gap for functional recovery, and how can these gaps be overcome? In order to resolve these questions, an experimental study was undertaken using sciatic nerves of the 83 mongrel adult dogs. A Two Stage Procedure for the neurorrhaphy was invented to overcome the large nerve defect. This method consists of the following two stages. The first stage operation is done by gradual approximation of both stumps against tension with a single and thick suture material. The second stage operation is done three weeks following the first stage operation, consisting of epineural suture under the microscope after refreshment of both stumps. The longest nerve defect in which axonal regeneration was accomplished by this Two Stage Procedure ranged 5 cm (proximal: 5.2% elongation, distal: 12% elongation) in the sciatic nerve of dogs.

Animals↗
PubMed1989

[A case of bilateral renal metastases from non Hodgkin's malignant lymphoma].

A patient with bilateral renal metastases from non Hodgkin's malignant lymphoma originating in the aortocaval abdominal lymph nodes was treated with chemotherapy. Initially, methotrexate (20 mg/m2), vincristine (0.6 mg/m2), cyclophosphamide (500 mg/m2), adriamycin (20 mg/m2), and bleomycin (30 mg/m2) were given on day 1, cisplatinum (50 mg/m2) was given on day 2, and prednisolone (20 mg/body) was given from day 1 to 3 (MVP-CAB regimen). Since the patient was 74 years old and had slight renal dysfunction, for the first and second courses of this therapy, methotrexate and cisplatinum were administered at 60% of the usual dose and the other 4 anticancer agents at 70% of the usual dose. Only prednisolone was given at the full dose. From the third course the 6 anticancer agents were used at 70% of the normal dose. Administration was performed every 4 weeks until the third course, and every 8 weeks after the fourth course (total number of cycles of MVP-CAB: 8 cycles). A marked improvement of the general state and a reduction of the tumor size were noted following treatment. Since regrowth of the residual tumor occurred, as second line chemotherapy cytosine arabinoside (100 mg/m2) on day 1, ifosfamide (1 g/m2) on day 1 to 2, etoposide (100 mg/m2) plus prednisolone (20 mg/body) on day 1 to 3 were administered (AraC-VIP regimen). The timing of administration was similar to that of the MVP-CAB regimen. More than 50% tumor reduction was obtained with this regimen. The total survival time since the beginning of chemotherapy is 2 years to date.

Aged↗
PubMed1989

Location of forelimb motoneurons in the Japanese toad (Bufo japonicus): a horseradish peroxidase study.

To label the spinal motoneurons innervating the forelimb muscles of the Japanese toad, horseradish peroxidase (HRP) was injected into these muscles or applied to the cut end of the brachial nerves (N. radialis and N. ulnaris). Spatial distribution of the HRP-labeled motoneurons was reconstructed from serial frontal sections of the spinal cord and their location was examined. Motoneurons innervating forelimb muscles were distributed in the lateral cell column from segment 3 to segment 5 of the ipsilateral brachial spinal cord. In the transverse plane of the spinal cord, motoneurons innervating the medial forearm muscles (innervated by N. ulnaris) were located in the more medial part of the lateral cell column, whereas those innervating the lateral forearm muscles and the upper arm muscle (innervated by N. radialis) were located in the more lateral part of the lateral cell column. Along the longitudinal axis of the spinal cord, motoneurons innervating the more anterior (flexor side) forearm muscles were located in the more rostral part of the spinal cord, whereas those innervating the more posterior (extensor side) forearm muscles were located in the more caudal part of the spinal cord. Thus, motoneurons innervating forearm muscles were well organized somatotopically not only in the transverse plane, but also along the longitudinal axis of the spinal cord. Such a somatotopic organization of motoneurons along the longitudinal axis could also be regarded as a functional one; the flexor motoneurons were located rostrally to the extensor motoneurons.

Animals↗
PubMed1989

The use of serum TA-4 in monitoring patients with malignant transformation of ovarian mature cystic teratoma.

The development of cancer in mature cystic teratomas of the ovary is rare and sometimes difficult to detect because of sampling errors. Six cases of squamous cell carcinoma arising in ovarian mature cystic teratomas were studied, five of which showed an elevated level of a squamous cell carcinoma-associated antigen, TA-4, in the sera obtained preoperatively; the preoperative determination was not performed in the sixth case. However, no elevated TA-4 level was detected in the sera of 28 patients with mature cystic teratomas of the ovary. Moreover, serial determination of the serum TA-4 level showed a good correlation between the clinical course and the serum TA-4 level. Interestingly, an abnormal TA-4 level preceded the clinical detection of recurrence by 2 months in two patients. Thus, determination of the serum TA-4 concentration may be useful for diagnosing and monitoring patients with squamous cell carcinoma arising in mature cystic teratomas of the ovary.

Adult↗
PubMed1989

Rabbit brain glucose transporter responds to insulin when expressed in insulin-sensitive Chinese hamster ovary cells.

Transfection of Chinese hamster ovary cells with the expression vector containing rabbit brain HepG2-type glucose transporter cDNA resulted in a dramatic over-expression (approximately 10-fold) of glucose transporter as assessed by either immunoblotting with antipeptide antibody against rabbit brain glucose transporter or photoaffinity labeling with [3H]cytochalasin B. 2-Deoxyglucose uptake was also increased 4-fold in the transfected cells, while no increase in transport activity or transporter amount was observed in cells that were transfected with the expression vector alone without glucose transporter cDNA. Significantly, insulin (10(-7) M) increased 2-deoxyglucose uptake in both control and transfected cells, but the increased amount of the transported 2-deoxyglucose by insulin in the transfected cells was 4.2-fold greater than that in control cells, indicating that the expressed rabbit brain HepG2-type glucose transporter responded to insulin. In addition, we have recently demonstrated that the HepG2-type glucose transporter exists in rat adipocytes and responds to insulin in a fashion similar to a majority of other types of glucose transporters (Oka, Y., Asano, T., Shibasaki, Y., Kasuga, M., Kanazawa, Y., and Takaku, F. (1988) J. Biol. Chem. 263, 13432-13439). In contrast, insulin did not stimulate glucose transport activity in HepG2 cells or IM-9 lymphocytes that have a significant amount of the HepG2-type glucose transporter. Thus, the results in this study further support the notion that insulin regulation of glucose transport activity depends on a tissue-specific signaling mechanism.

Affinity Labels↗
PubMed1989

Synthesis of hepatitis B virus e antigen in E. coli.

Hepatitis B virus core antigen (HBcAg) gene was deleted at some unique restriction enzyme sites, or at random, and inserted into the expression plasmids of E. coli which had the tryptophan promoter. E. coli transformants with the plasmids, synthesized materials with many kinds of antigenicity of HBcAg, HBeAg, or both HBcAg and HBeAg. HBeAg-specific material smaller than native HBeAg was produced in a stable condition.

Amino Acid Sequence↗
PubMed1989

Diagnosis of myocardial ischemia by the pressure-rate quotient and diastolic time interval during coronary artery bypass surgery.

Diagnosis of intraoperative myocardial ischemia by the rate-pressure product (RPP), pressure-rate quotient (PRQ), and diastolic time interval (DTI) was studied in 13 patients undergoing coronary artery bypass grafting (CABG) with fentanyl, vecuronium/pancuronium, and enflurane anesthesia. Criteria for ischemia were 1 mm of ST segment elevation or depression or T wave inversion on the ECG. RPP was calculated by multiplying the systolic arterial pressure (SAP) times the heart rate (HR); PRQ was determined by dividing the mean arterial pressure (MAP) by the HR; and DTI was defined as the interval from the closure of the aortic valve on M-mode transesophageal echocardiography to the onset of the QRS complex on the ECG. Six of 13 patients experienced episodes of ischemia (a total of 32 episodes out of 134 measurements). RPP of 12,000 was not found to correlate with myocardial ischemia (P greater than 0.05), whereas PRQ of less than 1.0 or DTI of less than 400 ms was associated with myocardial ischemia (P less than 0.005). In this preliminary study, it is concluded that both the PRQ and DTI are indicators of myocardial ischemia; it is also suggested that ischemia may be prevented by maintaining (1) DTI over 400 ms (HR less than 75 beats per minute), and (2) PRQ greater than 1.0 (MAP greater than HR).

Anesthesia, General↗
PubMed1989

Reordering of nine exons is necessary to form a functional actin gene in Oxytricha nova.

During the development of a macronucleus from a micronucleus after cell mating in hypotrichs all the genes (approximately 20,000) are excised from micronuclear chromosomes as individual small DNA molecules. Telomeres are added to the ends of each gene-sized molecule and each is amplified, mostly by approximately 1000-fold, to yield a transcriptionally active macronucleus. As a part of the study of the excision of genes from chromosomes, we have cloned six fragments of chromosomal DNA from Oxytricha nova, each containing a full copy of an actin gene, for comparison with the structure of the actin-encoding DNA molecule in the macronucleus. All six micronuclear actin clones had the same overall organization as judged by restriction mapping. Two micronuclear actin clones were sequenced. These differ from one another at a few nucleotide positions but both prescribe precisely the same actin polypeptide. Both micronuclear actin genes contain nine exons separated by eight intron-like sequences. The macronuclear gene contains these nine exons without intron-like segments. Assigning the order 1 through 9 to the nine micronuclear exons, the order in the macronucleus is 8-7-1-2-4-3-5-9-6. In the micronuclear actin gene, all nine exons possess terminal repeat sequences. These repeat sequences provide precise directions for reordering and joining of the nine exons to yield the exon order in the macronuclear gene. Polymerase chain reaction analysis of micronuclear DNA of the related species, Oxytricha trifallax, shows that the actin gene has an unorthodox arrangement in this species also.

Actins↗
PubMed1989

Hemodynamic effects of high-frequency jet ventilation in dogs with a chronically banded pulmonary artery.

Two to seven weeks after banding the main pulmonary artery, the hemodynamic effects of high-frequency jet ventilation (HFJV) and conventional mechanical ventilation (CMV) were studied in dogs with and without PEEP. In comparison with CMV, HFJV significantly increased cardiac index, stroke index (SI), left ventricular stroke work index, and oxygen delivery index, and decreased pulmonary vascular resistance index both with and without PEEP; however, there were significant decreases in PaO2 and increases in intrapulmonary physiologic shunt ratio in HFJV without PEEP. SI without PEEP was significantly greater with HFJV when the peak airway pressure was synchronized with the diastole in pulmonary arterial pressure (PAP) than with CMV and with HFJV synchronized with the systole in PAP. These findings suggest that HFJV has hemodynamic advantages over CMV in dogs with chronically banded pulmonary artery and dilated right ventricle.

Airway Resistance↗
PubMed1989

Isolation and characterization of temperature-sensitive mutants of Abelson murine leukaemia virus that exhibit dissociation among morphological transformation, soft agar colony-forming ability and tyrosine kinase activity.

Seven temperature-sensitive (ts) mutants of Abelson murine leukaemia virus (A-MuLV) were isolated on the basis of the temperature dependence of their soft agar colony-forming ability. These seven ts mutants exhibited similar characteristics and were not ts for morphological transformation and autophosphorylation of P120gag-abl protein. The dissociation of the properties of morphology, soft agar colony formation and tyrosine kinase activity might suggest that the v-abl product has more than one primary intracellular target.

Abelson murine leukemia virus↗
PubMed1989

Saccharomyces cerevisiae protein kinase dependent on Ca2+ and calmodulin.

A Ca2+- and calmodulin (CaM)-dependent protein kinase of Saccharomyces cerevisiae was partially purified by CaM affinity chromatography of the soluble fraction, and the properties of the enzyme were investigated. The protein kinase activity of the affinity-purified preparation was stimulated at least eightfold by the simultaneous presence of Ca2+ and CaM. The enzyme stimulation was strongly inhibited by trifluoperazine (TFP), a CaM antagonist. When the kinase was incubated in the presence of ATP, Ca2+, and CaM before the assay, the enzyme showed activity even in the presence of the Ca2+ chelator ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA) and TFP. The conversion to this Ca2+- and CaM-independent form occurred very rapidly under the incubation conditions required for protein phosphorylation by the kinase. At the highest level of conversion, Ca2+- and CaM-independent kinase activity, which was measured in the presence of EGTA and TFP, was nearly equal to the total kinase activity, which was measured in the presence of Ca2+ and CaM. A protein with a molecular weight of 58,000 was the major species that was phosphorylated in a Ca2+- and CaM-dependent manner by incubation of the CaM affinity-purified proteins with [gamma-32P]ATP. The protein kinase activity of the protein with the same molecular weight was demonstrated by in situ protein phosphorylation in sodium dodecyl sulfate-polyacrylamide gels by using casein as the substrate, after removal of the detergent from electrophoresed CaM-binding proteins. These data indicate that phosphorylation of the kinase is responsible for the conversion of enzyme activity. Enzyme regulation by this mode may play an important role in integrating cellular functions during the cell cycle. A possible role for the Ca2+-and CaM-dependent protein kinase in the signal transduction of the mating pheromone alpha factor is also discussed.

Calcium↗
PubMed1989

Rat epidermal growth factors: purification and tissue content.

Rat epidermal growth factor (rEGF) was isolated from the submaxillary gland of male rat by reversed phase high performance liquid chromatography and ion exchange chromatography. The binding of purified rEGF to human carcinoma cells (A-431) and its tritiated thymidine uptake on rat epidermal fibroblast cells (FR) were almost the same as those of purified commercially available mouse EGF (mEGF). Antisera to rEGF was raised in rabbits and a radioimmunoassay (RIA) system was established. The assay range of the RIA was about 1.0 to 100 ng/ml. The within assay coefficients of variation were 5 to 10%, while the between assay coefficients of variation were 5 to 13%. The tissue content of rEGF of male rats (10 weeks old) was examined. As a result, the submaxillary gland was found to contain a very high concentration of rEGF (214 micrograms/g wet tissue) as predicted, and digestive tissues, stomach, intestine and duodenum contained 2.49, 3.57, 9.44 ng/g wet tissue, respectively. The amounts in prostate and seminal vesicle were relatively high, being 65.6 and 2,268 ng/g wet tissue, respectively. The amount in the submaxillary gland increased markedly after 7 weeks of age. These results suggest that EGF is an important factor in gonadal function.

Aging↗
PubMed1989

Neuronal organization of the supracommissural ventral telencephalon and the nucleus preopticus periventricularis in the himé salmon (landlocked red salmon, Oncorhynchus nerka): a Golgi study.

The neuronal organization of the supracommissural ventral telencephalon (Vs) and the nucleus preopticus periventricularis (NPP) of the medial preoptic area (MPOA) in the himé salmon (landlocked red salmon, Oncorhynchus nerka) was studied by means of the Nissl staining and the rapid Golgi methods. The Vs was composed of many laterally-orienting spiny neurons and a few sparsely-spined polymorphous neurons. Some of the laterally-orienting neurons extended their dendrites into the lateral forebrain bundle (LFB), suggesting that they may receive inputs from the telencephalofugal and telencephalopetal fibers in the LFB. The NPP consisted of five types of sparsely-spined neurons: laterally-orienting, bipolar, cerebrospinal fluid (CSF)-contacting, commissural, and multipolar neurons. Some of the laterally-orienting neurons extended their dendrites into the medial forebrain bundle (MFB) and regions near the LFB, suggesting that they may also receive inputs from the telencephalofugal and telencephalopetal fibers running there. The presence of the CSF-contacting neurons in the NPP suggests that the NPP may receive humoral informations from the CSF. Involvement of these CSF-contacting neurons in the control of the reproductive functions was discussed. The neuronal organization of the NPP in the himé salmon was compared with that of the MPOA in other vertebrates.

Animals↗
PubMed1989

Clinical significance of the free vascularized bone grafts in fractures with large bone defects and non-union.

With the rapid progress of microscopic techniques in surgery, the free vascularized bone graft has been widely applied in fractures with large bone defects, non-union, congenital pseudoarthrosis, bone tumors, osteomyelitis, aseptic necrosis of the bone and osteogenesis imperfecta. We obtained excellent results with the free vascularized bone graft in three cases. One was a case of non-union with large bone defects of the right femur that had not improved despite many attempts at treatment over nine years after an open fracture of the right femur. The other two cases were open fractures with massive bone defects of the right legs. These results are reported here with an outline of the free vascularized bone graft.

Adult↗