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Biomedical subjects

T Nakashima

Publications and source records attributed to T Nakashima.

At least 343 records · Page 19Linked to original sources
PubMed1993

Phosphorylation of rat brain nicotinic acetylcholine receptor by cAMP-dependent protein kinase in vitro.

The participation of protein kinases in phosphorylation of nicotinic acetylcholine receptor (nAChR) in electric organ and muscle has been precisely investigated in vitro and in vivo whereas phosphorylation of neuronal nAChR is not yet fully characterized. Here, we first report the in vitro phosphorylation of brain nAChR. nAChR purified from rat brains was phosphorylated in vitro by cAMP-dependent protein kinase (PKA), immunoprecipitated with monoclonal antibody against the receptor, and subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) followed by autoradiography. PKA specifically phosphorylated nAChR on the alpha 4 subunits, and H8, an inhibitor of PKA, inhibited completely the phosphorylation. Under the conditions used, a maximal stoichiometry of the phosphorylation by PKA was near to 1 mol of phosphate/mol of the alpha 4 subunits. The 32P-labeled subunits were digested with S. aureas V8 protease followed by SDS-PAGE autoradiography and the resultant phosphopeptide maps revealed three distinct phosphopeptide bands, one major band and two minor bands. Phosphoamino acid analysis of the 32P-labeled alpha 4 subunits showed that serine residues were exclusively phosphorylated. Based on these results, participation of PKA in the regulation of neuronal nAChR is discussed.

Animals↗
PubMed1993

Oxytocin inhibits nonphasically firing supraoptic and paraventricular neurons in the virgin female rat.

Nonphasically firing activities were recorded from neurons in the supraoptic (s.o.) and paraventricular (p.v.) nucleus of the virgin female, male, and ovariectomized rat hypothalamic slice preparations. Following bath application of oxytocin (OXT), less than 1.0 x 10(-8) M, 24 (75%) of 32 virgin female s.o. neurons showed inhibitory responses and only one neuron showed excitatory response. In contrast to virgin female, five (63%) of eight male s.o. neurons were excited by OXT application. The same tendency was shown in the p.v. neurons. Among six s.o. neurons obtained from ovariectomized virgin rats, five neurons increased their firing rate to the application of OXT. After blocking synaptic transmission, the inhibitory responses of virgin s.o. neurons and the excitatory responses of ovariectomized virgin s.o. neurons to application of OXT were still observed with equal configurations. These findings suggest that the responses of nonphasic neurons to OXT may not due to synaptic drives.

Action Potentials↗
PubMed1993

Oxytocin modulates oxytocin neurons in the paraventricular nuclei of female rats throughout pregnancy and parturition.

OBJECTIVE: The physiologic roles of nonphasic firing oxytocin neurons in the paraventricular nucleus of female rats throughout pregnancy and parturition was studied from the viewpoint of changes in the membrane activities. STUDY DESIGN: Thin colonal hypothalamic slices containing the paraventricular nucleus were prepared. Immunohistochemical studies of oxytocin in the paraventricular nucleus were performed to determine the localization of oxytocin-containing neurons. Extracellular single neural activities were recorded with a glass micropipette from the oxytocin-dense area, and physiologic concentrations of oxytocin were applied. RESULTS: Nonphasic firing activity was recorded from 61 neurons in virgin female, pregnant, delivering and lactating rats. After bath application of < 5.0 x 10(-11) mol/L of oxytocin, firing rates of 12 of 17 paraventricular neurons in virgin rats decreased and only one increased, whereas the remaining four showed no response to oxytocin. In pregnancy at day 15 all four neurons decreased in activity, whereas at day 21 rats 20 of 26 neurons decreased, two increased, and four showed no response. On the contrary, in delivering rats seven of eight neurons exhibited excitatory responses, and only one showed no response. This excitation reversed to inhibition again after the lactating period ended. CONCLUSION: Negative feedback by oxytocin in virgin and pregnant rats might reverse to positive feedback in delivering and lactating animals as a result of changes in hormonal conditions. This reverse might be closely related to the initiation of delivery.

Action Potentials↗
PubMed1993

Effects of bile acids and taurine on the lipid fluidity of hepatic microsomes in normal and bile duct-ligated rats--a spin label study.

In cholestasis and obstructive jaundice, hepatic bile acids and taurine content increase significantly and bile acids change in compositions. For example, increases in cholic acid, beta-muricholic acid and taurine-conjugated bile acids occur in rats. In this study, to clarify the significance of changes in bile acid composition in obstructive jaundice, the effects of various bile acids and taurine on the fluidity of the hepatic microsomal membrane were studied by the electron spin resonance spin-label method in normal and bile duct-ligated (for 10 days) rats. The flow properties (order parameter) of the shallow and deep layers of the membrane were determined with 5- and 12-doxyl stearic acid, respectively. Bile acids mainly affected the fluidity of the shallow membrane layer. The fluidity of the hepatic microsomal membrane was decreased in bile duct-ligated rats. Conjugated cholic acid (taurine-conjugated cholic acid, glycine-conjugated cholic acid and non-conjugated beta-muricholic acid exerted effects that increased fluidity in comparison with non-conjugated cholic acid and chenodeoxycholic acid, a precursor of beta-muricholic acid. Taurine had no clear effect on fluidity. In conclusion, cholic acid conjugation and beta-muricholic acid formation may be mechanisms which protect against the decrease in lipid fluidity of hepatic biomembranes in cholestasis or obstructive jaundice. Taurine may also affect fluidity through the formation of taurine-conjugated bile acids.

Animals↗
PubMed1993

Phospholipase C activity in cerebrospinal fluid following subarachnoid hemorrhage related to brain damage.

Phosphoinositide-specific phospholipase C (PLC) activities were measured in CSF from patients after subarachnoid hemorrhage (SAH). Their PLC activities were significantly higher than those in control CSF. Moreover, there was an obvious correlation between the PLC activity in CSF collected on day 3 and the preoperative clinical grade. The PLC activity was also closely correlated with the level of neuron-specific enolase as a marker of brain damage. Furthermore, the PLC activities were partially purified from CSF of patients after SAH and were immunologically identified to be PLC beta, PLC gamma, and PLC delta. These results suggest that PLCs are released into the CSF from brain tissue in conjunction with the initial hemorrhage and that their activity may reflect the extent of brain damage.

Aneurysm, Ruptured↗
PubMed1993

Ureaplasma urealyticum in the urogenital tract of patients with chronic prostatitis or related symptomatology.

To elucidate the role of Ureaplasma urealyticum as a causative organism in chronic prostatitis we investigated its incidence in the urogenital tract in 131 chronic prostatitis patients and 120 prostatodynia patients; the presence of common bacteria or Chlamydia trachomatis was also recorded. According to the 4-glass localisation test, U. urealyticum (> or = 10(3) ccu/ml) was isolated from the prostates of 16 prostatitis patients and 2 prostatodynia patients; 5 of these prostatitis patients (but neither of the prostatodynia patients) had other bacteria in specimens after prostatic massage. Thus U. urealyticum was the sole organism isolated from the prostates of 11 prostatitis and 2 prostatodynia patients, which suggests that it is an aetiological agent in some cases of chronic non-bacterial prostatitis.

Adult↗
PubMed1993

Molecular cloning of a human cDNA encoding a novel protein, DAD1, whose defect causes apoptotic cell death in hamster BHK21 cells.

The tsBN7 cell line, one of the mutant lines temperature sensitive for growth which have been isolated from the BHK21 cell line, was found to die by apoptosis following a shift to the nonpermissive temperature. The induced apoptosis was inhibited by a protein synthesis inhibitor, cycloheximide, but not by the bcl-2-encoded protein. By DNA-mediated gene transfer, we cloned a cDNA that complements the tsBN7 mutation. It encodes a novel hydrophobic protein, designated DAD1, which is well conserved (100% identical amino acids between humans and hamsters). By comparing the base sequences of the parental BHK21 and tsBN7 DAD1 cDNAs, we found that the DAD1-encoding gene is mutated in tsBN7 cells. The DAD1 protein disappeared in tsBN7 cells following a shift to the nonpermissive temperature, suggesting that loss of the DAD1 protein triggers apoptosis.

Amino Acid Sequence↗
PubMed1993

Occurrence of melanosome-containing Merkel cells in mammalian oral mucosa.

The occurrence and fine structure of Merkel cells with melanosomes in the labial epithelium of the dog and cat were studied by electron microscopy. These melanosomes were polarized in the Merkel cell cytoplasm opposite to the major aggregation of dense-cored granules and the closely abutting nerve terminal. None of melanosomes was found in the Golgi complex region where a few immature dense-cored granules were observed. This may suggest that the melanosomes are not produced in the Merkel cell, but are taken from the melanocytes like in keratinocytes. The possible phagocytotic ability of Merkel cells is discussed.

Animals↗
PubMed1993

Spontaneous passage of upper urinary tract calculi in relation to composition.

The composition of 2,755 calculi obtained from the upper urinary tract (1,409 by spontaneous passage and 1,346 by urological procedures) was analyzed using an infrared spectrophotometer, and the spontaneous passage rate was investigated in relation to the composition as well as other variables, such as stone size, and patient age and sex. Mixed stones of calcium oxalate and calcium phosphate were most frequently found, followed by those of calcium oxalate. The mean size (the maximum diameter) was largest in struvite stones and smallest in calcium oxalate ones. The sizes of stones from women were significantly larger than those from men (p < 0.01). As expected, the stone passage rates were inversely related to increasing stone size. The size of 55.6% of the stones passed was < or = 5 mm, and that of 96.6% of the stones < or = 10 mm.

Adolescent↗
PubMed1993

Antimicrobial treatment for chronic prostatitis as a means of defining the role of Ureaplasma urealyticum.

A study was conducted to assess the clinical and microbiological effects of antimicrobial treatment for chronic prostatitis as a means of defining the role of Ureaplasma urealyticum. Significant U. urealyticum cells were considered to be isolated from the prostates of 18 of 143 prostatitis patients. These patients with ureaplasma-associated prostatitis were randomly treated with either ofloxacin or minocycline for 2 weeks; 4 patients were excluded due to voluntary withdrawal. U. urealyticum was eradicated in all the patients. Symptoms were resolved in 10 patients, and leukocytes in expressed prostatic secretion were cleared in 4 patients; both drug treatments revealed similar results. Even if we exclude 3 patients with significant coexistent Staphylococcus epidermidis cells before treatment, 3 of 11 patients evaluated showed complete resolution of symptoms and clearance of leukocytes in expressed prostatic fluid. These results suggest that U. urealyticum is a causative organism in some patients with chronic prostatitis.

Adult↗
PubMed1993

Assessment of pulmonary artery pressure by pulsed Doppler echocardiography in patients with chronic pulmonary diseases.

Doppler echocardiography was recently developed for obtaining a flow velocity profile at any point in the cardiac chamber. A pulsed Doppler technique combined with cross sectional echocardiography was used to examine the flow velocity pattern in the right ventricular outflow tract in 32 patients with chronic pulmonary disease (CPD) and in 15 healthy subjects as controls. All patients underwent cardiac catheterization. Pulmonary flow velocity profiles in the right ventricular outflow tract were recorded simultaneously with electrocardiograms and pre-ejection periods (PEP), right ventricular ejection time (RVET), acceleration time (AT), and calculated PEP/RVET, AT/RVET were determined. All normal subjects had "dome-like" flow velocity patterns with a peak flow at the midsystole. In patients with CPD, there was a significant correlation between log10MPAP (mean pulmonary arterial pressure) and AT/RVET, the coefficient being r = -0.623, between PVR (pulmonary vascular resistance) and AT/RVET (r = -0.52), and between SVI (stroke volume index) and PEP (r = -0.645). Complications of pulmonary hypertension in CPD were relatively mild, but the pulsed Doppler technique was found useful for evaluating pulmonary arterial pressure and other right heart hemodynamics of CPD patients.

Adolescent↗
PubMed1993

Outcome of sudden deafness with and without vertigo.

The outcome of unilateral sudden deafness with and without vertigo was evaluated according to the severity of the initial hearing loss, the shape of the audiogram, and other variables. The subjects for this investigation were 1313 patients who had presented to the authors' university hospital from 1972 to 1990 within 2 weeks of the onset of hearing loss. Thirty percent of the patients had accompanying vertigo. Vertigo occurred frequently in patients with severe hearing loss in the high-tone frequencies. Hearing recovery of high-tone frequencies was worse in patients with vertigo than in those without vertigo even when the initial hearing loss was the same. It is hypothesized that these results can be explained by anatomical factors; the cochlear basal turn being more proximal to the vestibular apparatus than the upper turn.

Adolescent↗
PubMed1993

Membrane lipid fluidity affects the nitroxide radical decay of 5-doxyl stearic acids in isolated rat hepatocytes.

We investigated the effect of membrane fluidity on the nitroxide radical decay rate of 5-doxyl stearic acid in spin-labeled rat hepatocytes. The half-time (t1/2) for the EPR signal decay of 5-doxyl stearic acids incorporated into the membranes of isolated rat hepatocytes was 12 min (mean value). When spin-labeled hepatocytes were separated into membrane and cytosol fractions, the t1/2 of the membrane fraction was prolonged by more than 2 hrs. However, when the cytosolic fraction was added to the membrane fraction, the radical decay reaction recovered (t1/2 was 27 min). Incubation of hepatocytes with a stream of 95% O2 at 37 degrees C for 2 hrs prolonged t1/2 by 106% and was associated with a 18% decrease in water-soluble antioxidant content. When the measurement temperature was changed from 24 degrees C to 37 degrees C, t1/2 was shortened with a decrease in the order parameter (S). The t1/2 and S in hepatocytes treated with phosphatidylcholine (PC) were reduced by 14% and 0.008, respectively. Conversely, after treatment with phosphatidylethanolamine (PE), PC+cholesterol and PE+cholesterol, t1/2 and S increased by 14% and 0.014, 20% and 0.018 and 29% and 0.040, respectively. These findings suggest that the nitroxide radical decay of 5-doxyl stearic acids incorporated into hepatocyte membranes is mediated by the antioxidants in the cytosol fraction, and that the nitroxide radical decay rate is affected not only by water-soluble antioxidant content but also by the membrane lipid fluidity of the hepatocytes.

Animals↗
PubMed1993

Clinical features of primary human herpesvirus-6 infection in an infant with acute lymphoblastic leukemia.

PURPOSE: The primary infection with human herpesvirus-6 developed concurrently with diagnosis of acute lymphoblastic leukemia and initiation of intensive chemotherapy for the disease in a 4-month-old girl. RESULTS: Prolonged viremia persisted for 7 days in the presence of neutralizing antibodies, and clinical features such as prolonged febrile and diarrheal period, no appearance of skin rash, and marked bulging fontanelle for 7 days in the absence of the virus DNA in spinal fluid may suggest an atypical clinical course of exanthem subitum and an unusual viral replication in immunocompromised condition.

DNA, Viral↗
PubMed1993

Drug resistance of coagulase-negative staphylococci from patients with urinary tract infection.

The drug resistance of 202 coagulase-negative staphylococci (CNS) strains isolated from patients with urinary tract infection (UTI) at urinary colony counts of 10(5) or more between 1989 and 1991 was studied. Of the 202 strains, 185 were submitted from UTI patients with underlying urinary disorders (complicated UTI patients) and became rapidly resistant to the majority of drugs tested. In addition, the incidence of methicillin-resistant or multiple drug resistant CNS tended to increase. These resistant strains were significantly more frequently isolated in patients with fever, which was strongly suspected to be due to CNS UTI. These results suggest that the prevalence of drug resistance in CNS from the urinary tract rapidly increases and drug-resistant CNS aggravate CNS UTI.

Anti-Infective Agents, Urinary↗
PubMed1993

[Effective regimen for eradication of Helicobacter pylori].

There is now substantial evidence that Helicobacter pylori (H. pylori) is both a frequent cause of chronic gastritis and an important factor in the recurrence of duodenal ulcer. However, to achieve the eradication of H. pylori is very difficult and although a number of treatment regimens suppress this organism, the stomach usually becomes recolonized shortly after the cessation of treatment. Many reports have shown that polytherapy is more effective than monotherapy. And so, the best results have been achieved with triple therapy using combination of bismuth, metronidazole, or tinidazole, and amoxicillin or tetracycline. The factor influencing effectiveness of triple therapy is compliance with the prescribed medications. And so, short term triple therapy is highly effective and well tolerated.

Anti-Bacterial Agents↗
PubMed1993

Deep and shallow forms of the sulcus for extensor carpi ulnaris.

Anatomical variations in the sulcus for the tendon of extensor carpi ulnaris were studied in 240 upper limbs. The sulcus lies between the head and the styloid process on the dorsal surface of the distal end of the ulna. This groove has deep and shallow forms and, rarely, a flat form. The sulcus was classified into 4 grades according to its depth. Grade I, a deep sulcus, was found in 51.3%. Grades II and III are shallow, but the styloid process in grade II is more prominent than in grade III. The former was found in 28.8%, the latter in 14.2%. Grade IV is a flat form. This was rare and found only in 1.3%. This variation was not age-related, but was a congenital feature.

Adult↗