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K Kitamura

Publications and source records attributed to K Kitamura.

At least 1,027 records · Page 57Linked to original sources
PubMed1987

Cellular calcium regulates outward currents in rabbit intestinal smooth muscle cell.

The nature of transient and oscillatory outward currents (ITO and IOO) in fragmented smooth muscle cells (smooth muscle ball, SMB) from the longitudinal muscle layer of the rabbit ileum, was studied using a single electrode voltage clamp technique. With a high K+ solution containing 0.3 mM ethyleneglycol-bis(beta-aminoethylether)-N,N'-tetraacetic acid (EGTA) in the pipette and physiological salt solution (PSS) in the bath, the Ca inward current was followed by a large transient outward current (ITO) and spontaneous oscillations of the outward current (IOO) on the sustained outward current (ISO) were elicited by a depolarizing pulse, positive to -30 mV (holding potential of -60 mV). When the internal fluid of the SMB was replaced with Cs+-tetraethylammonium+ (TEA+) solution, or when the concentration of EGTA in the pipette was increased to 4 mM, using the intracellular perfusion technique, both ITO and IOO were abolished. In Mn2+ solution both currents were also inhibited. Bath application of TEA+, procaine or A23187 completely blocked both ITO and IOO. Caffeine (0.3-1 mM) enhanced the amplitude of ITO and generations of IOO, and concentrations of caffeine over 3 mM transiently enhanced, but finally suppressed both these currents. These results suggest that the generation of ITO is closely related to the Ca2+ influx, whereas the generation of IOO may be initiated by an increment in the intracellular concentration of Ca2+, possibly released from store sites.

Animals↗
PubMed1987

Development and application of confined blasting for bladder and kidney stones.

Microexplosion lithotripsy (MEL) was clinically developed for the destruction of urinary stones in our clinic in 1981. In MEL two kinds of blasting are available: external charge blasting and confined blasting. The detonation power of the latter is 3 times larger than that of the former. Up to July, 1986, microexplosion cystolithotripsy has been successfully performed on 100 cases. In the early stages only external charge blasting was used. It was, however, not easy to crush a big bladder stone over 5 cm in diameter. For that reason, confined blasting was newly developed and in 50 cases microexplosion cystolithotripsy using confined blasting was completed successfully. As the next step, percutaneous nephrolithotripsy using confined blasting has been successfully performed on 12 cases including 3 of staghorn calculi.

Aged↗
PubMed1987

Three-dimensional vectorcardiography (3-D VCG) by computer graphics in old myocardial infarction.

By using computer graphics we rotated the vector loop and three coordinate axes to find the viewpoint where the infarctional changes are maximally exposed and demonstrated the advantage of the "3-D VCG" over the conventional VCG by defining the quantitative "MI index." The orthogonal electrocardiogram recorded by the Frank lead system was digitally measured and processed by a microcomputer. The loops and axes were rotated about the X axis (X-rot) and the Y axis (Y-rot). The spatial vector loop and orthogonal coordinates can be presented as viewed from any spheric direction. Eight quadrants were illustrated with four colors and red circles. The subjects consisted of 30 patients with old anterior myocardial infarction (MI) and 15 patients with old inferior MI. We measured the area of "Bite" in anterior MI and superior displacement in inferior MI. The MI index was defined and averaged in 361 directions. In anterior MI, the maximum mean index was obtained when X-rot is +90 degrees and Y-rot -40 degrees, viewed from upward and leftward, whereas in inferior MI it was obtained when X-rot is -50 degrees and Y-rot -80 degrees, viewed from downward and leftward. These values were significantly higher than those in conventional VCG projections, substantiating superior diagnostic sensitivity of 3-D VCG.

Adult↗
PubMed1987

Treatment of lethal pertussis vaccine reaction with histamine H1 antagonists.

We studied mortality after pertussis immunization in the mouse. Without treatment, 73 of 92 animals (80%) died after injection of bovine serum albumin (BSA) on day +7 of pertussis immunization. After pretreatment with 3 mg of cyproheptadine, 2 mg mianserin, or 2 mg chlorpheniramine, only 5 of 105 animals (5%) died after receiving BSA on day +7 (p less than 0.001). Blockade of histamine H1 receptors may reduce mortality in pertussis immunization-induced encephalopathy in mice.

Animals↗
PubMed1987

Dialysis dysequilibrium syndrome in neurosurgical patients.

Four neurosurgical patients with acute renal failure are presented. Intracranial pressure (ICP), cerebrospinal fluid (CSF) osmolality, and plasma osmolality were measured before, during, and after hemodialysis. There was an increase in ICP during all six hemodialyses performed on these patients. An osmolality gradient was established between the plasma and the CSF during four hemodialyses performed on two patients but not during one hemodialysis on one other patient. Continuous ventricular drainage and ICP monitoring were simple and effective clinical methods to avoid irreversible herniation during hemodialysis in these patients. A review of the literature on, proposed pathogenesis of, and prophylactic possibilities for dialysis dysequilibrium syndrome in neurosurgical patients is presented.

Acidosis↗
PubMed1987

Effects of methyl (+) (3S)-1,2,3,4-tetrahydro-3-hydroxymethyl-beta-carboline-2- carbodithioate(THC), a new hepatoprotective agent, on protein synthesis and chronic liver injury induced by carbon tetrachroride in rats.

The effects of oral administration of methyl (+) (3S)-1,2,3,4-tetrahydro-3-hydroxymethyl-beta-carboline-2-carbodithioa te (THC) on protein synthesis in the liver and chronic liver injury induced by carbon tetrachloride (CCl4) in rats were studied. THC increased liver weight and the contents of protein and ribonucleic acid, but not deoxyribonucleic acid, in the liver. THC also accelerated the 14C-leucine incorporation into hepatic microsomal and cytosol proteins in rats when the animals were treated with THC 24 h before sacrifice. In addition, when the animals were treated with THC during the latter half of a 5 weeks CCl4-treatment period, THC had a marked therapeutic effect on CCl4-induced chronic liver injury in rats by an improvement of the decreased body weight gain, suppression of the elevated serum enzyme activities (glutamic pyruvic transaminase, glutamic oxaloacetic transaminase and alkaline phosphatase) and increases in the decreased serum total protein and glucose contents. In the liver, THC also improved the decreased protein content, the increased triglyceride content and histopathological changes. These results suggested that THC stimulates protein synthesis in the liver and has a therapeutic effect on chronic liver injury induced by CCl4.

Animals↗
PubMed1987

Hyperosmotic blood-brain barrier disruption in brains of rats with an intracerebrally transplanted RG-C6 tumor.

To test the results of blood-brain barrier (BBB) disruption in the treatment of brain tumor, RG-C6 glioma was transplanted into the brains of rats. Intracarotid infusions of normal saline and hyperosmotic mannitol were then made, followed by intravenous injection of Evans blue dye plus albumin (EB, MW 68,000), horseradish peroxidase (HRP, MW 40,000), and 5-fluorouracil (5-FU, MW 130). Uptake of the drug and the consistency of drug levels in the normal brain and tumor varied widely among these three agents. Both EB and HRP penetrated the brain tumors but did not stain the normal brain tissues. After BBB opening, penetration of EB and HRP into the normal brain was drastically increased; however, the uptake of EB and HRP in the tumor was not increased. The concentration of 5-FU in the tumor was higher than that in the serum and, although it increased 1.5-fold after BBB opening, the increase was not statistically significant. Conversely, there was a progressive increase in concentrations of 5-FU in the tumor-free brain regions (p less than 0.05). These observations suggest that an intracarotid infusion of hyperosmotic mannitol may increase neurotoxicity because it allows greater delivery of anticancer drugs into the normal brain tissue than into the tumor tissues.

Animals↗
PubMed1987

Actions of nicorandil on vascular smooth muscles.

The action of nicorandil on vascular smooth muscles has been studied in vitro using the microelectrode, Ca-transient, isometric tension recording methods, and the bioassay methods of cyclic nucleotides and inositol phospholipids. Nicorandil increased Ca-insensitive K conductance and hyperpolarized the membrane and thus prevented the activation of the voltage-dependent Ca channel. The hyperpolarization occurred to a greater extent in venous tissue than in arterial tissue. Nicorandil stimulated the synthesis of cyclic guanosine monophosphate (cGMP) in the polarized and depolarized muscle tissues, as did nitroglycerin. Consequently, nicorandil reduces the concentrations of free Ca in the myoplasm, due to acceleration of the Ca pump at the sarcolemma, and may prevent the phosphorylation of myosin through phosphorylation of myosin light chain kinase. These actions of nicorandil may not contribute to the synthesis of inositol-1,4,5-trisphosphate hydrolyzed from phosphatidylinositol-4,5-bisphosphate. The above actions of nicorandil--hyperpolarization and increase in the cyclic GMP--may cause relaxation of the tissues precontracted by various stimulants.

Action Potentials↗
PubMed1987

Expression of myelin protein genes in the developing brain.

The major myelin proteins fall into two classes, the basic proteins and the proteolipid proteins. In mice, five forms of the myelin basic protein (MBP) have been identified with apparent molecular masses of 21.5 kD, 18.5 kD, 17 kD and 14 kD. The 17 kD MBP variant consists of two molecular forms with similar molecular masses but different amino acid sequences. Cell-free translation studies and analyses of MBP cDNAs have shown that each of the MBP variants is encoded by a separate mRNA of approximately 2 000 bp. The five mouse MBP mRNAs appear to be derived by alternative splicing of exons 2, 5, and 6 of the MBP gene. cDNAs encoding four forms of MBP have been isolated from a human fetal spinal cord library. The mRNAs corresponding to these cDNAs are probably derived by alternative splicing of exons 2 and 5 of the human MBP gene. Proteolipid protein (PLP) cDNAs have been isolated from several species and used to establish that the size of the major PLP mRNA is approximately 3 kb. Multiple size classes of the PLP mRNAs exist in mice and rats whereas the 3 kb mRNA is the predominant form in the developing human spinal cord. In normal mice, maximal expression of the PLP gene lags behind that of the MBP gene by several days. Studies on dysmyelinating mutants have determined some of the molecular defects with respect to these two classes of myelin proteins. For example, there is a deletion of a portion of the MBP gene in the shiverer mutant. In the quaking mutant, the expression of both classes of myelin proteins is significantly reduced prior to 3 weeks. However, after 3 weeks, MBP expression approaches normal levels but the newly synthesized protein fails to be incorporated into myelin. In the jimpy mutant, although the expression of both classes of proteins is reduced, PLP expression is most severely affected.

Animals↗
PubMed1987

Plasma concentration of human atrial natriuretic polypeptide in patients with impaired renal function.

Using direct radioimmunoassay, the plasma concentration of human atrial natriuretic polypeptide (hANP) was measured in patients with impaired renal function. Patients on maintenance hemodialysis (HD) and those still on medical management (non-HD) were examined. In 13 non-HD patients with serum creatinine values from 2.0 to 8.3 mg/dl, mean plasma hANP (+/- SE) was 404 +/- 23 pg/ml, while it was 236 +/- 11 pg/ml in the normal control group (n = 15) and the difference was significant (p less than 0.001). In all patients as a whole, there was a positive correlation between plasma hANP and mean blood pressure (r = 0.56, p less than 0.05) but no correlation was present between plasma hANP and renal function. Fifty-six HD patients were divided into 2 groups depending on blood pressure level. Plasma levels of hANP in the hypertensive (BP greater than or equal to 150/90 mmHg, n = 21) and in the normotensive (BP less than 150/90 mmHg, n = 35) HD group were 588 +/- 58 pg/ml and 364 +/- 29 pg/ml, respectively, with plasma hANP in both HD groups significantly higher than in the controls (p less than 0.001). There was also a significant difference of plasma hANP between hypertensive and normotensive HD patients (p less than 0.01). However, when the normotensive HD group without cardiomegaly (cardiothoracic ratio less than 50%, n = 17) was compared with the control, the value of plasma hANP was not statistically different from that of the control group. These results suggest that plasma hANP in patients with impaired renal function is influenced by blood pressure and/or cardiac condition.

Adult↗