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Biomedical subjects

H Hirata

Publications and source records attributed to H Hirata.

At least 217 records · Page 12Linked to original sources
PubMed1989

Spinocervical tract neurons responsive to light mechanical stimulation of the raccoon forepaw.

1. The extracellular activity of 45 antidromically identified spinocervical tract (SCT) neurons responsive to light mechanical stimulation of the glabrous surfaces of the forepaw was examined in raccoons anesthetized with pentobarbital sodium. An additional seven neurons had peripheral receptive fields (RFs) located on hairy skin of the forelimb, and three had deep RFs. 2. All recording sites were histologically verified as falling within Rexed's laminae III and IV in spinal cord segments C6-T1. Antidromic conduction velocities of the 55 neurons ranged between 8.3 and 64.2 m/s. 3. Units with glabrous skin RFs were classified according to their response to a maintained mechanical stimulus as either rapidly adapting (n = 39) or slowly adapting (n = 6). Of 11 cells tested, 2 displayed enhanced responses to noxious stimuli and were classed as multireceptive. 4. RF areas were significantly smaller on digits (range = 0.4-45.0 mm2) than on palm pads (range = 5.6-76.0 mm2), and comparable in size to RF areas previously reported in raccoon cuneate nuclear cells (32). 5. RA neurons fell into three distinct categories with respect to the relationship between instantaneous spike frequency during displacement ramp stimulation, and ramp velocity, steep functions (as defined by the value of power function exponents), flat functions, and discontinuous functions; SA neurons fell into two categories, continuous, and discontinuous. 6. The results, in conjunction with those of previous studies, lead to two major conclusions: 1) raccoon and primate spinocervicothalamic systems are more similar to each other than either is to that of the cat and 2) the ability of the raccoon SCT to convey information from the glabrous skin of the forepaw regarding characteristics of light mechanical stimuli is at least as precise as that of neurons of the dorsal column-medial lemniscal system.

Afferent Pathways↗
PubMed1989

Chronic sinusitis and woodworking as risk factors for cancer of the maxillary sinus in northeast Japan.

In the period 1983 to 1985, 66 patients presented to six Japanese university hospitals with squamous cell carcinoma of the maxillary sinus. Using self-administered questionnaires, a case-control study was conducted to examine history of nasal diseases, occupational exposures, and other possible risk factors for this disease. For each patient, two controls were selected from the general population, matched to the patient by sex, age (+/- 5 years), and district of residence. A history of chronic sinusitis was associated with a 2.3-fold increase in risk (p = 0.05). A high relative risk was also observed in males with an occupational history of woodworking or joinery, particularly when these jobs involved sanding or lathing practices (RR = 7.5, p = 0.02). No association between cigarette smoking and maxillary sinus cancer was observed in this study and no evidence was found that indoor air pollution in the home is involved in cancer development.

Adult↗
PubMed1989

[Interstitial radiotherapy of carcinoma of the tongue-comparison between Jacobson-Yamamoto grading and prognosis].

One hundred and one patients of less than seventy years old with T1, T2 and N0 carcinoma of the tongue were graded according to the Jacobson-Yamamoto's grading (1-4 D). All patients were also classified into two groups such as less than fifty years old group and fifty to seventy years old group. Patients with grade 3, 4 C and 4 D carcinoma had more metastases to the cervical lymph nodes than grade 1, 2. Patients with T2N0 carcinoma showed approximately same five year cervical lymph node metastases free survival rate. However, the five year survival rate of less than fifty years old group was significantly lower than that of fifty to seventy years old group. In T2N0, grade 3-4 D carcinoma cases, more dead cases were found in less than fifty years old group than in fifty to seventy years old group.

Adult↗
PubMed1989

[Protective effect of specific human immunoglobulins on haematogenous osteomyelitis by Staphylococcus aureus in mice].

Effects of specific human immunoglobulins extracted from pooled human sera on the protection of the production of haematogenous osteomyelitis by a strain of Staphylococcus aureus in mice were studied. No multiplication of the organisms in mouse bone marrow was observed by intravenous injection of strain SMU01 of Staphylococcus aureus when 2.20mg protein of specific immunoglobulins was administered prior to the injection of the strain. Roentgenographic examinations in mice revealed no destructive findings around the proximal and distal metaphysis of the femur at one to two weeks after the injection, indicating absence of macroscopic abscess formation in these area. These results suggest a possible therapeutic effect of specific human immunoglobulins on human staphylococcal osteomyelitis.

Animals↗
PubMed1989

[An effect of the clenching speed on the method of calculating the biting force of patients by using electromyography].

The recovery of the masticatory function in patients with dentures was assessed by several indices such as masticatory efficiency, maximal biting force and electromyographic analysis. We have attempted to develop a new method of calculating the biting force of edentulous patients by using electromyography. The method has almost been established, but, depending on the clenching speed, there is a certain difference between the estimates obtained from this method and the biting force obtained from a force transducer. The purpose of this study is to clarify the effect of the clenching speed on the method of calculating the biting force by using electromyography. In 9 healthy subjects with normal dentitions, biting force and electromyograms were recorded simultaneously under 3 different clenching speed conditions. After the recording, the relation between the biting force and integrated electromyography was compared thoroughly. The effect of the clenching speed on the method of calculating the biting force by using electromyography was also investigated. The following results and conclusions were obtained: 1. At a slow clenching speed, a linear relation between the biting force and integrated electromyography was found. 2. At a medium clenching speed, the relation showed a slightly upward curvature as the biting force was increased and a slightly downward curvature as it was decreased. 3. At a fast clenching speed, the relation between the biting force and integrated electromyography showed an upward curvature as the biting force was increased, and a downward curvature as it was decreased. 4. At the slow and medium clenching speeds the estimates obtained from this method approximated the biting forces obtained from a force transducer. 5. At the fast clenching speed, the tendency was found that the estimates obtained from this method were higher than the biting force obtained from a force transducer. 6. When realizing this tendency, the method of calculating the biting force by using electromyography can be said to be clinically effective.

Bite Force↗
PubMed1988

Solubilization and reconstitution of voltage-dependent calcium channel from bovine cardiac muscle. Ca2+ influx assay using the fluorescent dye Quin2.

Highly purified sarcolemmal membranes, prepared from fresh bovine heart left ventricle, were solubilized by n-octyl beta-D-glucopyranoside and reconstituted into proteoliposomes with soybean phospholipids by the detergent-dialysis method. Ca2+ flux into the proteoliposomes was determined using the fluorescent probe Quin2. A membrane potential (negative in the proteoliposome interior) that was created by K+ diffusion mediated by valinomycin accelerated the Ca2+ influx. The voltage-dependent Ca2+ influx was dependent on pretreatment of the sarcolemmal membranes with Bay K 8644 and was inhibited by various calcium antagonists including nicardipine (K0.5 = 4.5.10(-7) M), verapamil (K0.5 = 9.2.10(-9) M), diltiazem (K0.5 = 26.10(-8) M) and omega-conotoxin (K0.5 = 9.5.10(-9) M).

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1988

Substitution of gamma Arg-275 by Cys in an abnormal fibrinogen, "fibrinogen Osaka II". Evidence for a unique solitary cystine structure at the mutation site.

In an abnormal fibrinogen with impaired fibrin monomer polymerization designed as fibrinogen Osaka II, we have identified substitution of Arg by Cys at position 275 of the gamma chain. This Cys is linked to a free cysteine molecule by a disulfide link as evidenced by fast atom bombardment mass spectrometry. This finding was supported by identification of a single cysteine released from isolated abnormal fragment D1 upon reduction. This unique cystine structure at the mutation site has not been reported heretofore in any abnormal protein including fibrinogen. The substitution may well perturb the structure required for fibrin monomer polymerization, specifically that assigned to the carboxyl-terminal D domain of fibrinogen. Indeed, isolated fragment D1 with the Cys substitution failed to inhibit thrombin-mediated clotting of normal fibrinogen and normal fibrin monomer polymerization, while normal fragment D1 inhibited them markedly. Our data seem to provide supporting evidence that the putative polymerization site(s) assigned to the D domain of fibrinogen may be structure-dependent, including the carboxyl-terminal segment of the gamma chain as well as a contiguous region that contains the gamma 275 residue.

Adolescent↗
PubMed1988

Calcium channel blockers inhibit bacterial chemotaxis.

The effect of several Ca2+ channel blockers, which inhibit the voltage-dependent Ca2+ uptake in Bacillus subtilis, on chemotactic behaviour of the bacterium was studied. Nitrendipine, verapamil, LaCl3 and omega-conotoxin were tested and these blockers inhibited chemotactic behaviour in the bacterium toward L-alanine. Among these blockers, omega-conotoxin was the most effective inhibitor of chemotaxis. EGTA was also as effective as omega-conotoxin. In contrast, these blockers, did not inhibit the motility and the growth of the bacterium. These results suggest that internal Ca2+ plays an important role in the sensory system of bacterial chemotaxis.

Bacillus subtilis↗
PubMed1988

Kinetic analysis of proton translocation catalyzed by F0F1 ATPase.

Kinetic analysis of both proton translocating and steady-state ATP hydrolytic activities catalyzed by F0F1 ATPase in submitochondrial particles were carried out over an ATP concentration range of 1-2000 microM. The results were examined in relation to the prediction based on the alternate binding change model proposed by Gresser et al. [(1982) J. Biol. Chem. 257, 12030-12038] in which energy transduction occurs only at the tri-site catalytic cycle. The present results essentially contrast with the model and rather indicate that if the alternate binding mechanism holds for the ATP hydrolytic reaction, the proton translocation should be coupled to at least both bi-site and tri-site cycles.

Adenosine Triphosphate↗
PubMed1988

Partial purification of alanine carrier from rabbit small intestine brush border membrane and its functional reconstitution into proteoliposomes.

An alanine transport carrier was partially purified from brush border membranes of rabbit small intestine. The alanine carrier activity was not solubilized with 0.4% deoxycholate but recovered in the detergent-insoluble fraction. The detergent-insoluble proteins were reconstituted into proteoliposomes with soybean phospholipids. The reconstituted proteoliposomes were capable of uptake of alanine driven by an electrochemical potential of Na+. The initial rate of alanine uptake into the proteoliposomes was 90 pmoles/mg protein/sec, which was 15-fold higher than that observed with the native membrane vesicles. The uptake of alanine was effectively suppressed by various neutral amino acids but not by either cationic or anionic amino acids.

Amino Acid Transport Systems↗
PubMed1988

Incorporation of partially purified cation channels from cardiac sarcolemmal membrane into planar lipid bilayers.

Voltage-dependent calcium channels are vital to cardiac muscle contraction. Therefore it is very important to isolate physiologically active channel proteins, however there have been few reports on their solubilization and reconstitution. Highly purified sarcolemmal membranes from bovine cardiac muscle were solubilized with octylglucoside, partially purified by gel filtration, and reconstituted into planar lipid bilayer by the direct insertion method. At least, two cation channel activities were observed: one with about 4.2 pS and the other with about 28 pS in conductance. From the reversal potential, it was concluded that Ba2+ ions are the current carrier through these two channels.

Animals↗
PubMed1988

Effect of radiation-induced injury of tumor bed stroma on metastatic spread of murine sarcomas and carcinomas.

The study was performed to determine whether irradiation of the tumor bed alters the propensity of tumors to metastasize, and if so, whether the effect is dependent on the property of tumors to exhibit the tumor bed effect (TBE). Ten tumors, of which 5 were sarcomas and 5 were carcinomas syngeneic to C3Hf/Kam mice, were used. Tumors were grown s.c. in the right thighs of mice that had or had not been irradiated with 20-Gy gamma-rays 1 day before tumor cell transplantation. All 5 carcinomas and 2 of 5 sarcomas exhibited TBE, as assessed by a significant retardation of growth rate. To test whether irradiation of the tumor bed influenced metastatic spread independently of TBE, tumors of various sizes were surgically removed, and at appropriate times thereafter the lungs were examined for the presence of metastases. All tumors that exhibited TBE, and only 1 of 3 tumors that did not exhibit TBE, metastasized more than tumors of the same size growing in an unirradiated tumor bed. TBE-induced enhancement of metastasis was not seen in tumors less than approximately 7 mm in diameter. All tumors, whether they exhibited TBE or not, were more necrotic if they grew in a preirradiated tumor bed. These observations show that size for size, most tumors growing in irradiated tissues have an increased propensity to metastasize, which is linked to their manifestation of TBE. The evidence presented suggests that TBE-induced retardation of tumor growth is the major factor responsible for the observed enhancement of metastasis. The clinical implication of these findings is that tumors recurrent after radiotherapy should be diagnosed and treated promptly to reduce the risk of metastatic spread.

Animals↗
PubMed1988

Sequence and over-expression of subunits of adenosine triphosphate synthase in thermophilic bacterium PS3.

The primary structures of all the subunits of thermophilic ATP synthase were determined, and its alpha, beta and gamma subunits could be over-expressed in Escherichia coli, because these subunits were stable and reconstitutable. DNA of 7500 base pairs in length was found to contain a cluster of nine genes for subunits of ATP synthase. The order of their reading frames (size in base pairs) was: I(381): a(630): c(216): b(489): delta(537): alpha(1507): gamma(858): beta(1419): epsilon(396), I being a gene for a small hydrophobic, basic protein expressed in vitro. All the termini of TF0F1 subunits were confirmed by peptide sequencing. Large quantities of the overexpressed thermophilic alpha, beta and gamma subunits were prepared from the extract of E. coli, by a few purification steps.

Amino Acid Sequence↗
PubMed1988

Changes of HDL subfraction concentration and particle size by intralipid in vivo.

The effects of the artificial triglyceride-phospholipid emulsion (10% intralipid) on HDL subfraction were studied in vivo. After a 14-h fast, subjects received intralipid via a 4-h infusion. Serum lipoproteins were analyzed before and at 4 and 6 h after the start of the infusion. At 4-h the following acute changes by infusion were observed. Triglyceride, phospholipid, free cholesterol, and esterified cholesterol in chylomicrons and VLDL increased. HDL2 as well as triglyceride, phospholipid, free cholesterol and protein within the HDL2 increased, while HDL3 decreased. An increase in HDL3 triglyceride was observed. The masses of apo A-I and A-II in the HDL2 density interval rose while these parameters fell in HDL3. There were decreases of apo C-II and C-III in the HDL subfractions and elevations in chylomicrons and VLDL. The particle size of the HDL subfractions increased. However, most of these acute changes at 4 h tended to disappear by 6 h. These results suggest that there is exchange of lipids and reversible transfer of apo C-II and C-III between HDL subfractions and intralipid, and conversion of HDL3 to HDL2 followed by the reverse conversion of HDL2 to HDL3 as the synthetic emulsion is cleared from the plasma.

Adult↗