Biomedical subjects

M Tsuruoka

Publications and source records attributed to M Tsuruoka.

At least 37 records · Page 2Linked to original sources

PubMed1997

[Rapid detection of the Escherichia cori verotoxin gene using fluorescence polarization].

The effects of NaCl concentration, temperature and base-pair mismatches on the hybridization of two complementary single-stranded DNA 24-mers were investigated using a fluorescence polarization method. Over a temperature range of 46 degrees C to 56 degrees C in 0.8 M NaCl it was found that hybridization was essentially complete in under 10 minutes and that rapid in vitro determination of the target DNA was possible when the sample DNA had three or less base-pair mismatches in the 24-mer sequence. Polarization measurements on positive and negative samples showed excellent agreement with results obtained from electrophoresis. Under our optimized conditions, a 23 base-pair single-stranded DNA sequence of the Verotoxin gene (VT2) of Escherichia coli, previously multiplied using PCR (40 cycles), could be detected within 10 minutes.

Bacterial Toxins↗

PubMed1996

Descending modulation from the region of the locus coeruleus on nociceptive sensitivity in a rat model of inflammatory hyperalgesia.

The aim of the present study was to evaluate the action of the descending modulation system from the locus coeruleus (LC) in a rat model of unilateral hyperalgesic inflammation. Unilateral hindlimb inflammation was produced by a subcutaneous injection of carrageenan (6 mg in 0.15 ml saline). One week before testing, rats received bilateral lesions of the LC using anodal current. Nociception was assessed by measuring withdrawal of the paw from a noxious thermal stimulus. Four hours after carrageenan injection, paw withdrawal latencies (PWLs) in the inflamed paw of the LC-lesioned rats were significantly shorter than those of the sham-operated rats. This difference in PWL between the two groups was not observed at 7 days, whereas edema and hyperalgesia still remained in the inflamed paw. At 4 h, systemic naloxone produced a further decrease of the PWL in the LC-lesioned rats but not in the sham-operated rats. These results suggest that inflammation-induced activation of the descending modulation system from the LC occurs in only the acute phase of inflammation and that a decrease in the extent of the development of hyperalgesia in the acute phase of inflammation might depend on the interaction between the descending modulation system from the LC and the opioid inhibitory system.

Analysis of Variance↗

PubMed1996

Optimization of the rate of DNA hybridization and rapid detection of methicillin resistant Staphylococcus aureus DNA using fluorescence polarization.

The hybridization rate of two complementary single-stranded DNA 24-mers was determined at various NaCl concentrations using a fluorescence polarization method. The rate was taken as the rate constant of the second order reaction, obtained by mathematical fitting of the time course curves of hybridization. The rate increased with the NaCl concentration, plateauing in the concentration range of about 1-2 M. Over the temperature range of 46 degrees C to 56 degrees C, it was found that in 0.8 M NaCl, hybridization was complete in under 10 min and that the difference in the polarization values between specific hybridization and non-specific binding was greater at lower temperatures. Under the optimized conditions of 0.8 M NaCl at 46 degrees C, the time for DNA hybridization to reach 90% completion decreased to less than 5 min. The assay time for one sample was 10 min and the detection limit was of the order of 10(-10) M (40 fmol per assay). Under the optimized conditions, the DNA of methicillin resistant Staphylococcus aureus (MRSA), which had been multiplied by PCR, could be detected within 10 min.

Base Sequence↗

PubMed1996

Bilateral lesions in the area of the nucleus locus coeruleus affect the development of hyperalgesia during carrageenan-induced inflammation.

We have compared the development of hyperalgesia following induction of unilateral inflammation between rats with bilateral lesions in the area of the locus coeruleus (LC) and rats with a sham operation. Unilateral inflammation was produced by the subcutaneous injection of carrageenan (6 mg in 0.15 ml saline). Prior to carrageenan injection, paw withdrawal latency (PWL) to thermal stimuli did not differ between the LC-lesioned and the sham-operated groups. After carrageenan injection, in the inflamed paw, the decreased PWLs of LC-lesioned rats were significantly shorter than those of sham-operated rats. This difference in PWL between the two groups was not observed in non-inflamed paws and in paws receiving an injection of saline. The result suggests that the area of the LC affects the development of hyperalgesia during peripheral inflammation.

Animals↗

PubMed1996

Mode of interaction of loop diuretics with human serum albumin and characterization of binding site.

PURPOSE: The purpose of this study was to investigate the binding mechanism of loop diuretics with HSA and to characterize the binding site on HSA. METHODS: Quantitative analysis of potential interaction between ligands bound to HSA was performed by equilibrium dialysis and data for binding of the two ligands to HSA were analyzed on the basis of a theoretical model of simultaneous binding of two ligands. RESULTS: The binding of loop diuretics is dependent upon the N-B transition, conformational change of albumin. Furthermore, from the results of binding of the drugs to modified HSA, the lysine residue seems to be involved in the binding of loop diuretics to HSA. CONCLUSIONS: Analysis using models describing independent, competitive, cooperative and anti-cooperative binding led to the conclusion that loop diuretics bind to site I, particularly to the warfarin region on HSA.

Binding Sites↗

PubMed1996

Activated eosinophils stimulate phosphatidylcholine secretion in primary culture of rat type II pneumocytes.

Activated eosinophils in airway epithelium are involved in the pathogenesis of many airway diseases. We examined whether activated eosinophils influence the secretion of phosphatidylcholine (PC), the predominant component of pulmonary surfactant, in primary culture of rat type II pneumocytes. The eosinophils (10(5) cells/ml) activated by opsonized zymosan (100 micrograms/ml) increased PC secretion from the type II pneumocytes. The increased PC secretion reduced in the presence of both superoxide dismutase (2 units/ml) and catalase (1000 units/ml). These results suggest that activated eosinophils stimulate the secretion of pulmonary surfactant partly through superoxide anions.

Animals↗

PubMed1995

Effects of xanthine derivatives on phosphatidylcholine secretion in primary culture of rat type II pneumocytes.

Xanthine derivatives, pentoxifylline, aminophylline, theophylline and chinoin-170, increased phosphatidylcholine secretion in a primary culture of rat type II pneumocytes. However, these xanthines alone had no effect on intracellular cAMP levels in type II pneumocytes. In contrast, terbutaline-induced secretion of phosphatidylcholine was augmented by these xanthines, and the augmentation depended on the increase of cAMP levels. These results suggest that the xanthines induce phosphatidylcholine secretion possibly through cAMP-dependent and cAMP-independent pathways in the primary culture of rat type II pneumocytes.

Aminophylline↗

PubMed1995

Protective effect of N-benzyl-D-glucamine dithiocarbamate against renal toxicity in rats during repeated cis-diamminedichloroplatinum administrations.

The protective effects of N-benzyl-D-glucamine dithiocarbamate (BGD) against the renal toxicity caused by repeated injections of cis-diamminedichloroplatinum (DDP) were studied in rats. The rats were injected i.p. with BGD (2.0 mmol/kg) immediately after i.v. injection of DDP (20 mumol/kg), and after 10 and 20 days they received repeated treatments with the same doses of DDP and BGD. Treatment with BGD prevented nephrotoxicity after repeated DDP administrations. Repeated DDP injections increased lipid peroxidation in the kidney and decreased GSH concentration in the kidney at 5 days after the third injection of DDP. BGD treatment prevented the increase in lipid peroxidation and the decrease in the GSH concentration caused by repeated administration of DDP. The determination of activities of antioxidant enzymes in the kidney showed that catalase activity decreased after repeated DDP administrations and that superoxide dismutase activity tended to decrease. Changes in activities of these enzymes were prevented by BGD treatment. The platinum concentrations in kidney and liver were decreased by BGD treatment. These results indicate that BGD treatment prevents the accumulation of platinum in the kidney after repeated administrations of DDP, resulting in protection against the DDP-induced renal toxicity.

Animals↗

PubMed1994

Interaction of benzothiadiazides with human serum albumin studied by dialysis and spectroscopic methods.

The interaction of a series of benzothiadiazides with human serum albumin (HSA) was investigated by equilibrium dialysis (ED) and spectroscopic methods including circular dichroism (CD). The primary binding site of benzothiadiazides was designated site II, the diazepam site on the HSA molecule, as indicated by displacement experiments using different site-selective probes. Tyrosine and lysine amino acid residues were probably involved in the binding site of these compounds to HSA. Both electrostatic and hydrophobic interactions were found to play a role in the binding of these compounds to HSA. Among the compounds tested, chlorothiazide had the highest affinity (K1 = 5.5 x 10(4) M-1, K2 = 5.8 x 10(3) M-1). The primary binding affinity of the compounds for HSA was of the order: chlorothiazide > cyclopenthiazide > polythiazide > ethiazide > trichlormethiazide = methyclothiazde > hydrochlorothiazide. Binding was insensitive to the N-B transition of HSA. The binding site is proposed to consist of a cationic site on the surface of the HSA molecular with a hydrophobic crevice to accommodate the aromatic ring of the compounds. Positions 3 and 7 of the benzothiadiazide molecule is thought to affect the binding affinity to HSA.

Benzothiadiazines↗

PubMed1994

Protective effects of dithiocarbamates against renal toxicity of cis-diamminedichloroplatinum in rats.

Sodium diethyldithiocarbamate (DDTC), sodium N-benzyl-D-glucamine dithiocarbamate (BGD), sodium N-p-hydroxymethylbenzyl-D-glucamine dithiocarbamate (HBGD), and sodium N-p-carboxybenzyl-D-glucamine dithiocarbamate (CBGD) were evaluated for efficacy as inhibitors of cis-diamminedichloroplatinum (DDP)-induced nephrotoxicity in a rat model. Treatments with 2.0 mmol/kg of BGD, HBGD, and CBGD immediately after DDP (20 mumol/kg) injection effectively prevented the nephrotoxic effects of DDP, but administration of DDTC immediately after DDP injection afforded a small protection. Concurrent treatment with 0.5 or 1.0 mmol/kg of HBGD, or 1.0 mmol/kg of CBGD could prevent DDP-induced renal damage. A significant decrease in weight loss was also observed in these dithiocarbamate-rescued rats. The platinum concentrations in liver and kidney were significantly decreased by BGD, HBGD, and CBGD treatments, respectively. The antitumor efficacy of DDP in the Walker 256 carcinoma-bearing rats was not affected by administration of HBGD (1.0 mmol/kg) or CBGD (1.0 mmol/kg). The results of this study indicated that the injection of HBGD or CBGD to rats treated with DDP can protect against DDP-induced nephrotoxicity more effectively than DDTC or BGD.

Animals↗

PubMed1993

Thalamic- and cerebellar-projecting interpolaris neuron responses to afferent inputs.

Thalamic- and cerebellar-projecting interpolaris neuron responses to afferent inputs from the temporomandibular joint (TMJ) and/or the masseter muscle (Mm) were examined in rats. Of 230 neurons tested, 24 could be antidromically stimulated from the contralateral ventral posteromedial thalamic nucleus (VPM), and 27 of 91 neurons tested were stimulated from the ipsilateral posteromedial part of crus II of the cerebellar cortex. None had dual projections. The thalamic-projecting neurons were recorded in the dorsomedial region of the interpolaris; most cerebellar-projecting neurons were at the medial border of the interpolaris. Ten of 24 thalamic- and 17 of 27 cerebellar-projecting neurons received nociceptive information. Afferent inputs from the TMJ and the Mm converged on 6 of 24 thalamic-projecting neurons and on 16 of 27 cerebellar-projecting neurons. In both the thalamic- and cerebellar-projecting neurons, there was no difference between the non-nociceptive and nociceptive neurons in mean antidromic latency. The results suggest that the interpolaris integrates and relays afferent inputs from deep oral structures.

Afferent Pathways↗

PubMed1991

Protection against cis-diamminedichloroplatinum-induced nephrotoxicity in rats by N-benzyl-D-glucamine dithiocarbamate.

Sodium N-benzyl-D-glucamine dithiocarbamate (BGD) was evaluated for its efficacy as an inhibitor of cis-diamminedichloroplatinum (DDP)-induced nephrotoxicity in a rat model. Treatment with 2.0 mmol/kg of BGD immediately after DDP injection effectively prevented nephrotoxic effects of DDP, but administration of BGD -1 or 1 h after DDP afforded a small protection. Concurrent treatment with 0.5 mmol/kg of BGD could not prevent renal damage. The platinum concentrations in liver and kidney were significantly decreased by BGD treatment. The antitumor efficacy of DDP in the Walker 256 carcinoma-bearing rats was not affected by administration of BGD (2.0 mmol/kg).

Animals↗

PubMed1991

Fluorescence polarization immunoassay employing immobilized antibody.

The use of an antibody immobilized on latex or silver colloid in fluorescence polarization immunoassay (FPI) is assessed. In FPI it is possible to detect antigens of high molecular weight because the molecular weight of the antibody is effectively increased. In the assay for rabbit immunoglobulin G a limit of detection lower by two orders of magnitude and an assay range wider by one order of magnitude can be obtained in comparison with conventional FPI. The detection limit is 10(-10) mol l-1 and the total assay time for one sample is 8 min. This assay combines a low detection limit with a short assay time.

Animals↗

PubMed1991

Effects of small myelinated afferent fiber stimulation on the threshold of tail flick reflex in the rat.

Effects of A-delta afferent fiber stimulation on the response threshold in the tail flick reflex were examined in rats anesthetized with thiamylal sodium. In a statistical analysis, the suppressive effect on the skin temperature at the time of the tail flick (tail flick temperature) was represented as a percent of maximal possible effect (%MPE) expressing more clearly the degree of change of the tail flick temperature. A-delta afferent fiber stimulation produced a reduction of EMG activity of the tail muscle, but no changes of both the tail flick latency and the tail flick temperature were observed. The results of the present study and the previously reported modulation system in the spinal cord dorsal horn are discussed.

Action Potentials↗

PubMed1990

Function of the conserved triad residues in the class C beta-lactamase from Citrobacter freundii GN346.

The conserved KTG triad in the class C beta-lactamase from Citrobacter freundii GN346 was examined as to its function by means of site-directed mutagenesis. The following conversions were performed; Lys-315 to arginine, alanine or glutamic acid, Thr-316 to valine, and Gly-317 to alanine, proline or isoleucine. The resultant mutant enzymes revealed that a basic amino acid at position 315 and a small uncharged residue at position 317 are essential for the enzyme activity, but a hydroxyl group at residue 316 is not required for the enzymatic catalysis. The kinetic properties of the purified Arg-315 and Val-316 enzymes provided information on the function of these residues.

Amino Acids↗

PubMed1990

Comparison of effectiveness of 3 dithiocarbamates on excretion and distribution of cadmium in rats and mice.

Sodium N-benzyl-D-glucamine dithiocarbamate (BGD), sodium N-p-methylbenzyl-D-glucamine dithiocarbamate (MBGD), and sodium N-p-isopropylbenzyl-D-glucamine dithiocarbamate (PBGD), which were recently synthesized, were evaluated for their efficacy in the distribution and excretion of cadmium in rats and mice exposed to cadmium. Rats and mice were injected i.p. with 109CdCl2 (1 mg Cd/kg and 2 microCi 109Cd/one animal) and 3 days later, they were treated with the dithiocarbamates (400 mumol/kg) every other day for 2 weeks. These dithiocarbamates were effective in removing cadmium from the body without increasing the cadmium content in the kidney. After treatment with BGD, MBGD, and PBGD, cadmium was excreted mainly in the feces and the effect of MBGD and PBGD on the fecal excretion of cadmium was much larger than that of BGD. The treatment with these dithiocarbamates did not cause the redistribution of cadmium to brain, testes, and heart in rats and mice. The treatment of mice with PBGD decreased the concentrations of essential metals in liver, kidney, and brain. The extent of acute toxicity of the dithiocarbamates in mice was in the order PBGD greater than MBGD greater than BGD.

Animals↗

PubMed1990

Nonsegmental inhibition of rat dorsal horn neurons by innocuous stimulation.

In rats anesthetized with thiamylal sodium, responses of spinal cord dorsal horn neurons to noxious skin heating of the tail were recorded by extracellular microelectrodes. Inhibition of these responses by innocuous mechanical stimulation (light brushing) of the ipsilateral forelimb was assessed. Short-lasting application (3 min, or less) of light brushing did not inhibit neuronal responses to noxious heating. Long-lasting application (5 min, or more) inhibited responses of these neurons to noxious stimulation. The results indicate that, in the anesthetized rat, remotely applied innocuous cutaneous stimuli can inhibit nociceptive responses of dorsal horn neurons, if applied for a sufficiently long time.

Afferent Pathways↗

PubMed1990

Inhibition of nociceptive responses of wide-dynamic-range neurons by peripheral nerve stimulation.

Of 107 neurons from the sacral and coccygeal levels of the spinal cord in anesthetized intact rats examined, 62 wide-dynamic-range (WDR) neurons that responded to noxious heating of the tail were recorded. On the basis of their inhibitory responses through A-beta or A-delta afferent fibers to noxious stimulation, these neurons were classified into one of the following three types: Type I--neurons inhibited only by A-beta afferent nerve impulses; Type II--neurons inhibited only by A-delta afferent nerve impulses; Type III--neurons inhibited by both. The present results are compared with previously reported behavioral results.

Animals↗