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Biomedical subjects

T Koyama

Publications and source records attributed to T Koyama.

At least 127 records · Page 7Linked to original sources
PubMed2000

Traumatic cardiac rupture with acute ascites.

A rare accumulation of serous ascites following traumatic cardiac rupture is reported for a 21-year-old man transferred to the emergency center of our hospital from a community hospital suffering from severe shock due to a motorcycle accident. Computed tomography scan showed moderate pericardial and intrapelvic fluid accumulation strongly suggesting cardiac and visceral injuries. An emergency sternotomy disclosed a rupture of the right atrial appendage, successfully closed with primary sutures. A laparotomy was done to aspirate moderate serous fluid, which was clear and not bloody. Edema of the retroperitoneal space and hepatic congestion were noted with no accompanying organ injury. Ascites pathogenesis is unknown but appeared to be related to portal venous congestion induced by cardiac tamponade combined with massive intravenous fluid infusion done to correct the patient's deteriorating hemodynamics.

Accidents, Traffic↗
PubMed2000

Surgery of basilar aneurysms associated with unexpected rupture of an internal carotid artery aneurysm.

During a surgery of basilar aneurysms via the trans-sylvian approach, we encountered an arterial bleeding caused by rupture of an internal carotid artery aneurysm that had been difficult to diagnose before surgery, as it was a small and brood-neck aneurysm and mimicked arteriosclerosis. In spite of several surgical procedures, the surgical path at the basilar aneurysms became narrow, and we had to abandon the clipping of the aneurysms. Consideration of radiological and intraoperative findings was made for this case, demonstrating a pitfall that neurosurgeons may encounter during surgery.

Aged↗
PubMed2000

Strength training with partial ischaemia stimulates microvascular remodelling in rat calf muscles.

The effects of strength training with partial tourniquet ischaemia on skeletal muscle capillarity were examined, particularly in terms of the distribution of arteriolar and venular capillaries and their capillary domain area, in male Wistar rats. A tourniquet applied around the knee joint induced partial ischaemia. Repeated isometric contractions of calf muscles, 1 s on/1 s off for 3 min, induced by electrical stimulation (100 Hz), were conducted 2 days/week for 6 weeks as training. Morphologic data were obtained from four groups; non-treatment control (C), ischaemic (IS), non-ischaemic training (NIT) and ischaemic training (IT). In the superficial portion of gastrocnemius (GASs) muscle, the total capillary density of arteriolar capillaries was significantly greater in the IT-leg than in the C-leg (P < 0.05). In the plantaris (PL) muscle, these values were significantly greater in the IT-leg than in both the C- and NIT-legs (P < 0.05). Only in the GASs was the capillary-to-fibre ratio significantly greater in the IT-leg than in the C-leg (P < 0.05). In GASs and PL, the capillary domain area (CDA) was smaller in the IT-leg than in the C- and NIT-legs. In all muscles examined, mean fibre cross-sectional area was not significantly changed by the experimental treatment. These findings suggest that adaptive changes in the microvascular network, identified as an increase in the arteriolar capillary area and a reduction in diffusion distance, occur in the skeletal muscles after strength training with partial ischaemia. These adaptive changes probably improve the supply of oxygen and nutrients to skeletal muscle tissues.

Animals↗
PubMed2000

Differential effects of subchronic treatments with atypical antipsychotic drugs on dopamine D2 and serotonin 5-HT2A receptors in the rat brain.

The effects of 3-week treatment with a typical antipsychotic drug chlorpromazine and three atypical antipsychotic drugs (risperidone, olanzapine and perospirone) on the binding to dopamine D2 and serotonin 5-HT2A receptors were examined in the rat stratum and frontal cortex, respectively. Subchronic treatment with chlorpromazine (10 mg/kg) and perospirone (1 mg/kg) significantly increased D2 receptors, while no increase was observed with lower dose of chlorpromazine (5 mg/kg), perospirone (0.1 mg/kg), risperidone (0.25, 0.5 mg/kg) or olanzapine (1, 2 mg/kg). On the other hand, 3-week administration of chlorpromazine (5, 10 mg/kg) and olanzapine (1, 2 mg/kg) significantly decreased 5-HT2A receptors, but risperidone (0.25, 0.5 mg/kg) or perospirone (0.1, 1 mg/kg) had no effect. The measurement of in vivo drug occupation for D2 and 5-HT2A receptors using N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline (EEDQ) suggested that high occupation of 5-HT2A receptors with lower D2 receptor occupancy might be involved in the absence of up-regulation of D2 receptors after subchronic treatment with some atypical antipsychotic drugs.

Animals↗
PubMed2000

Functional coupling of GABA(B) receptors with G proteins that are sensitive to N-ethylmaleimide treatment, suramin, and benzalkonium chloride in rat cerebral cortical membranes.

Although it is known that GABA(B) receptors are negatively coupled to adenylyl cyclase, the detailed selectivity of functional interaction between GABA(B) receptors and Gi subfamily members is still ambiguous. (+/-)-Baclofen-stimulated high-affinity GTPase activity, which was competitively antagonized by 2-hydroxy-saclofen, was attenuated by pretreatment of the membranes with N-ethylmaleimide (NEM) in a concentration- and incubation period-dependent manner. The NEM-pretreated (50 microM, 15 min at 4 degrees C) membranes restored the (+/-)-baclofen-sensitive high-affinity GTPase activity when reconstituted with pertussis toxin-sensitive bovine brain G proteins. Among recombinant rat Galpha subunits, G(i alpha(-2)) appeared most effective as compared with other subunits (G(i alpha(-2)) > G(i alpha(-3) > G(i alpha(-1) = G(o alpha). The GABA(B) receptor-mediated high-affinity GTPase activity was also completely eliminated by 100 microM suramin and by 100 microM benzalkonium chloride. These results indicate that GABA(B) receptors in rat cerebral cortex couple to NEM-sensitive G proteins, in particular Gi2, which are sensitive to suramin and benzalkonium chloride.

Adenylate Cyclase Toxin↗
PubMed2000

Endoscopic injection sclerotherapy for esophageal varices prolonged survival of patients with hepatocellular carcinoma complicating liver cirrhosis.

BACKGROUND: A prospective controlled study was performed between 1982 and 1991 to evaluate the efficacy of endoscopic injection sclerotherapy (EIS) in patients with esophageal varices complicated by hepatocellular carcinoma and liver cirrhosis. METHODS: The study included 83 patients with esophageal varices, hepatocellular carcinoma, and liver cirrhosis. Forty-three patients (group 1) underwent prophylactic EIS or emergent EIS for bleeding varices. EIS was performed weekly 4 to 6 times until the varices disappeared. The remaining 40 patients (group 2) underwent conservative therapy and did not undergo EIS. Survival rates were compared between the 2 groups. RESULTS: During the 5-year observational period, all patients who did not undergo EIS died. Sixteen in group 2 (40.0%) died of gastrointestinal bleeding including ruptured esophageal varices. In contrast, patients treated with EIS survived significantly longer (p<0.001). Nine patients (20.9%) treated with EIS experienced gastrointestinal bleeding as a result of which 5 (11.6%) died. EIS prolonged survival in patients classified as Child's A or B but did not affect survival in patients with Child's C hepatic function. EIS was effective in prolonging survival in patients with hepatocellular carcinomas smaller than 5 cm. However, EIS had no effect in patients with hepatocellular carcinomas that were larger than 5 cm. EIS prolonged survival only for patients with nodular hepatocellular carcinoma and had no effect in patients with massive and diffuse hepatocellular carcinoma. Further, EIS prolonged survival only for patients who did not have portal vein thrombosis. CONCLUSION: Based on this prospective study, we concluded that EIS was effective in prolonging the survival period of a select subset of patients with hepatocellular carcinoma.

Aged↗
PubMed2000

Renal disease in women with severe preeclampsia or gestational proteinuria.

OBJECTIVE: To identify women with severe preeclampsia or severe gestational proteinuria at high risk of having underlying renal disease. METHODS: Between 1980 and 1999, 86 Japanese women who had severe hypertension, severe proteinuria, or both during pregnancy had postpartum needle biopsies of their kidneys. Diagnoses before biopsies were severe preeclampsia in 74 women and severe gestational proteinuria in 12. We compared clinical characteristics, such as antepartum hematuria and postpartum proteinuria, and maternal and neonatal outcomes with regard to presence of renal disease. RESULTS: Nineteen of 86 women (22.1%, 95% confidence interval [CI] 13.9%, 32. 3%) were diagnosed with underlying renal disease. Immunoglobulin A nephropathy was present in 12. Women with renal disease had a significantly earlier onset of proteinuria than those without (median 11 versus 32 weeks' gestation, P <.001). Eighteen of 19 women with renal disease had proteinuria, hypertension, or both before 30 weeks' gestation. Ten of 12 women with severe gestational proteinuria (83.3%, 95% CI 51.6%, 97.9%) had underlying renal disease. Eight of the 19 women had antepartum hematuria, and seven had elevated serum immunoglobulin A levels. In women with severe preeclampsia, onset before 30 weeks' gestation was the best predictor of underlying renal disease (odds ratio 34.1, 95% CI 3.8, 304.5). Women with renal disease had lower rates of severe hypertension (nine of 19 versus 59 of 67, P <.01) and small-for-gestational-age infants (four of 19 versus 34 of 67, P <.05) than those without renal disease. CONCLUSION: Women who had gestational proteinuria or preeclampsia before 30 weeks' gestation were more likely to have had underlying renal disease.

Adult↗
PubMed2000

Effect of the dopamine D(1/5) antagonist SCH 23390 on the acquisition of conditioned fear.

The authors previously reported that typical and atypical antipsychotic drugs inhibited the acquisition but not expression of conditioned fear. The present study examined the effects of the selective dopamine D(1/5) agonist (SKF 38393) and antagonist (SCH 23390) on the acquisition and expression of conditioned fear. Drugs were administered subcutaneously to male Sprague-Dawley rats 30 min before foot shock (2.5 mA for 5 min). Twenty-four hours after foot shock, rats were again placed and observed in the shock chamber without shocks (conditioned fear). Freezing behavior induced by conditioned fear, an index of anxiety or fear, was recorded using a time-sampling procedure. SCH 23390 (0.1-1 mg/kg) inhibited the acquisition of conditioned freezing. The administration of SCH 23390 at a dose of 0.1 mg/kg 30 min after foot shock did not affect conditioned freezing. Taken together, it is concluded that D(1/5) antagonism inhibits the acquisition of conditioned fear. SKF 38393 (3-20 mg/kg) failed to change the acquisition of conditioned fear. SCH 23390 or SKF 38393 administered prior to testing did not reduce the expression of conditioned fear. These results suggest that D(1/5) receptors may play a role in the development of fear or anxiety.

Animals↗
PubMed2000

The role of benzodiazepine receptors in the acquisition and expression of behavioral sensitization to methamphetamine.

The GABA-benzodiazepine neurotransmission has been reported to be implicated in various forms of plasticity such as kindling and learning. In a previous study, we have shown that clonazepam (CZP), a GABA-benzodiazepine agonist, prevents the acquisition of behavioral sensitization to methamphetamine (MA). The present study was conducted to extend this finding by examining the effect of flumazenil (Flu), a GABA-benzodiazepine antagonist on the prevention by CZP. Rats (male Wistar-King rats) treated with MA (1 mg/kg, SC) for 10 days showed significantly enhanced motor activity compared to those treated with saline when tested with MA (1 mg/kg) after a 7-8-day withdrawal, indicating the acquisition of behavioral sensitization. Representing the previous finding, pretreatment with CZP (0.5 mg/kg) prior to MA administration prevented the acquisition of the phenomenon. Pretreatment with Flu (10 mg/kg) prior to MA administration has no influence on the acquisition of sensitization. However, pretreatment with Flu prior to CZP administration reversed the inhibitory effect of CZP. CZP showed no effect on the expression of sensitization in the sensitized rats when given prior to the MA readministration. These results strengthen the suggestion that stimulation of GABA-benzodiazepine receptors plays a role in the acquisition but not in the expression of behavioral sensitization to MA.

Animals↗
PubMed2000

Open pergolide treatment of tricyclic and heterocyclic antidepressant-resistant depression.

BACKGROUND: Recently, a dopamine hypothesis of depression was put forward, and several studies have demonstrated that direct and indirect dopamine agonists have antidepressant effects. METHODS: Using Clinical Global Impressions, we evaluated the efficacy of 4-week treatment of pergolide as an antidepressant adjuvant involving 20 unipolar depressed patients who were refractory to standard treatment with antidepressants. RESULTS: One patients (5%) were very much improved, seven (35%) much improved, four (20%) minimally improved, six (30%) no change or worse, and two (10%) not assessed. There was no significant difference in any clinical factors between the pergolide responder and non-responder group. LIMITATIONS: This study was a non-blind open trial, and pergolide was added to tricyclic and heterocyclic antidepressants. CONCLUSION: Pergolide may be useful as an antidepressant adjuvant, suggesting a potential role for dopamine-2 stimulation in the antidepressant response.

Adult↗
PubMed2000

Treatment response in depressed patients with enhanced Ca mobilization stimulated by serotonin.

Serotonin (5-HT)-stimulated intraplatelet calcium (Ca) mobilization has been shown to be enhanced in nonmedicated depressive patients by many studies. However, there has not been any longitudinal follow-up study of this parameter. We examined the relationship between treatment response and pretreatment value of the 5-HT-induced Ca response. The 5-HT(10 microM)-induced intraplatelet Ca mobilization was measured in 98 nonmedicated depressive patients (24 bipolar disorders, 51 melancholic major depressive disorders, and 23 non-melancholic major depressive disorders). These patients were followed up prospectively for a further period of five years. The depressed patients with enhanced Ca response to 5-HT in bipolar disorders exhibited a good response to mood stabilizers but those with major depressive disorders showed a poor response to antidepressants. These findings suggest the possibility that the 5-HT-induced intraplatelet Ca response may be a good predictor of treatment response in depressed patients. Longer longitudinal follow-up studies are needed in larger samples to examine if this parameter may be a specific biological marker for unipolar-bipolar dichotomy.

Adult↗
PubMed2000

Clinical factors associated with post-ictal headache in patients with epilepsy.

OBJECTIVES: To determine the incidence of post-ictal headaches (PIH) and clinical risk factors associated with the occurrence of PIH in patients with localization-related epilepsy. MATERIALS AND METHODS: The subjects were 77 patients with temporal lobe epilepsy (TLE), 34 patients with occipital lobe epilepsy (OLE), and 50 patients with frontal lobe epilepsy (FLE). The subjects were directly asked whether headaches occurred just after seizures. Medical charts were reviewed to ascertain the clinical characteristics of epilepsy in these patients. RESULTS: The incidence of PIH was 23% for TLE, 62% for OLE, and 42%, for FLE. The risk of PIH was significantly higher for OLE than for TLE or FLE, and for patients with generalized tonic-clonic seizures. Younger age at onset of epilepsy was also a risk factor for PIH. CONCLUSION: The occurrence of PIH may be related to the region of epileptic focus and the region of spread of epileptic discharges.

Adolescent↗
PubMed2000

Pharmacological characterization of metabotropic glutamate receptor-mediated high-affinity GTPase activity in rat cerebral cortical membranes.

Activation of heterotrimeric guanine nucleotide-binding regulatory proteins (G-proteins) functionally coupled to metabotropic glutamate receptors (mGluRs) was assessed by agonist-induced high-affinity GTPase (EC3.6.1.-) activity in rat cerebral cortical membranes. L-Glutamate (1 mM) stimulated high-affinity GTPase activity to the same extent throughout the incubation period up to 20 min, in a Mg(2+)-dependent manner. The addition of 1 mM L-glutamate augmented V(max) of the enzyme activity (1670 to 3850 pmol mg(-1) protein 15 min(-1)) with slight increase in K(M) value (0.26 to 0.63 microM). The high-affinity GTPase activity was stimulated by the following compounds with a rank order of potency of (2S,2'R,3'R)-2-(2', 3'-dicarboxycyclopropyl) glycine (DCG-IV) > (2S,1'S, 2'S)-2-(carboxycyclopyropyl)glycine (L-CCG-I) > L-glutamate > or = 2R, 4R-4-aminopyrrolidine-2,4-dicarboxylate [(2R,4R)-APDC] > 1S, 3R-1-aminocyclopentane-1,3-dicarboxylate [(1S,3R)-ACPD] > (S)-4-carboxy-3-hydroxyphenylglycine [(S)-4C3HPG] > (S)-3-carboxy-4-hydroxyphenylglycine [(S)-3C4HPG] > ibotenate, but not by L-(+)-2-amino-4-phosphonobutyrate (L-AP4), (RS)-3, 5-dihydroxyphenylglycine [(RS)-3,5-DHPG], quisqualate, or L-serine-O-phosphate (L-SOP), indicative of involvement of group II mGluRs, in particular mGluR2. (2S)-alpha-Ethylglutamate (EGLU), a presumably selective antagonist against group II mGluRs, inhibited DCG-IV-stimulated high-affinity GTPase activity in a competitive manner with an apparent K(B) of 220 microM. L-Glutamate-stimulated activity was eliminated by pretreatment of the membranes with sulfhydryl alkylating agent N-ethylmaleimide (NEM) at 30-50 microM, indicating that G-proteins of the G(i) family are involved. These results indicate that mGluR agonist-induced high-affinity GTPase activity in rat cerebral cortical membranes may be used to detect the functional interaction between group II mGluRs, in particular mGluR2, and NEM-sensitive G(i) proteins.

Animals↗
PubMed2000

Mechanism of product chain length determination for heptaprenyl diphosphate synthase from Bacillus stearothermophilus.

A member of the medium-chain prenyl diphosphate synthases, Bacillus stearothermophilus heptaprenyl diphosphate synthase, catalyzes the consecutive condensation of isopentenyl diphosphate with allylic diphosphate to produce (all-E)-C35 prenyl diphosphate as the ultimate product. We previously showed that the product specificity of short-chain prenyl diphosphate synthases is regulated by the structure around the first aspartate-rich motif (FARM). The FARM is also conserved in a subunit of heptaprenyl diphosphate synthase, component II', which suggests that the structure around the FARM of component II' regulates the elongation. To determine whether component II' regulates the product chain length by a mode similar to that of the short-chain prenyl diphosphate synthases, we replaced a bulky amino acid at the eighth position before the FARM of component II', isoleucine 76, by glycine and analyzed the product specificity. The mutated enzyme, I76G, can catalyze condensations of isopentenyl diphosphate beyond the native chain length of C35. Moreover, two mutated enzymes of A79Y and S80F, which have a single replacement to the aromatic residue at the fourth or the fifth position before the FARM, mainly yielded a C20 product. These results strongly suggest that a common mechanism controls the product chain length of both short-chain and medium-chain prenyl diphosphate synthases and that, in wild-type heptaprenyl diphosphate synthase, the prenyl chain can grow on the surface of the small residues at positions 79 and 80, and the elongation is precisely blocked at the length of C35 by isoleucine 76.

Alkyl and Aryl Transferases↗
PubMed2000

Acute thrombocytopenia associated with post-streptococcal acute glomerulonephritis.

A case of acute thrombocytopenia associated with post-streptococcal acute glomerulonephritis is described. The patient showed a mild glomerulonephritis and a remarkable increase of platelet-associated immunoglobulin G (PAIgG). The relation between the mild degree of glomerulonephritis and the high PAIgG value is discussed.

Acute Disease↗
PubMed2000

Differences in electroencephalogram power densities between genuine narcolepsy and secondary narcolepsy.

Diagnosing narcolepsy is not always simple. Some patients secondarily show narcoleptic tetrad through irregular sleep patterns or psychotic diseases. The power densities of daytime electroencephalograms in genuine narcolepsy and secondary narcolepsy were analysed and compared. Electroencephalogram power densities for a 6.5-h period after waking in genuine narcoleptic patients were lower than those of secondary narcoleptic patients in the 11.0-12.5 Hz bands. Arousal levels may be lower in genuine narcoleptic patients than in secondary narcoleptic patients. Spectral analysis may be useful in clarifying differences between the two groups.

Adolescent↗
PubMed2000

Autonomic nervous function after evening bright light therapy: spectral analysis of heart rate variability.

In order to investigate the effects of 5000 lx evening bright light on autonomic nervous function, a spectral analysis was used to assess heart rate variability in consecutive 5-min epochs just after 60 min of bright light therapy was given to 12 young women (range: 20-21 years of age). The study revealed that a low frequency band (LF) increased in bright light conditions (BL) in comparison with controlled conditions (CL). High frequency band (HF), LF:HF ratio and the coefficient of variance (CV R-R) were not significantly different between the two conditions. These results indicate that 5000 lx evening bright light may affect sympathetic nervous system activity in healthy women.

Adult↗