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Biomedical subjects

M Shibayama

Publications and source records attributed to M Shibayama.

At least 19 recordsLinked to original sources
PubMed2001

Entamoeba histolytica: production of nitric oxide and in situ activity of NADPH diaphorase in amebic liver abscess of hamsters.

Entamoeba histolytica trophozoites were inoculated into the liver of hamsters and serum nitrate/nitrite levels [expressed as nitric oxide (NO) production] were determined at different times during amebic liver abscess (ALA) development. We also tested the effects of NO synthase (NOS) inhibitors such as N(G)-nitro-L-arginine methyl ester (L-NAME), aminoguanidine, and dexamethasone during ALA production. Since NOS activity has been correlated with expression of reduced nicotinamide adenine dinucleotide phosphate diaphorase (NADPHd) in tissues, we performed histochemistry studies to determine the activity of the latter in livers infected with E. histolytica trophozoites. Production of NO in serum was directly proportional to the size of ALAs, and NOS inhibitors caused low levels of NO and smaller ALAs. Our data suggest that NO does not have any lytic effect on E. histolytica trophozoites and is therefore incapable of providing protection against the amebic liver infection. In addition, NADPHd activity was detected histochemically in hepatocytes and inflammatory cells associated with focal necrosis containing trophozoites. The positive reactivity observed in these parasites may be attributable to a close biochemical similarity of NADPHd to the NADPH:flavin oxidoreductase described in E. histolytica by other investigators.

Animals↗
PubMed2001

IgA and IgM anti-Naegleria fowleri antibodies in human serum and saliva.

Antibodies from IgA and IgM classes that recognize Naegleria fowleri (Nf) proteins were detected by the ELISA assay in serum and saliva from three groups of people: (i) subjects with upper respiratory tract infections (URTI) living in the parasite-endemic area, (ii) healthy persons from the same area, and (iii) healthy persons from a parasite-nonendemic area. In serum and in saliva the titers of IgA antibodies to Naegleria fowleri in the group of patients with URTI was significantly higher than that of the healthy group in the parasite-endemic area; also the titers of IgM antibodies in serum were significantly higher in patients. On the contrary, in saliva the antibodies were higher in healthy people from the parasite-endemic area. In all cases the subjects from the parasite-nonendemic area had lower antibody titers in serum and saliva.

Adult↗
PubMed2000

Interaction of antibodies with Entamoeba histolytica trophozoites from experimental amebic liver abscess: an immunocytochemical study.

Using immunocytochemical techniques, we studied the interaction of antibodies with Entamoeba histolytica trophozoites present during the development of amebic liver abscess. Hamsters were intrahepatically inoculated with HM1-IMSS axenic amebas and sacrificed at different days post-inoculation. IgG of rabbit anti-E. histolytica and IgG of rabbit anti-IgG of hamster were used, both labeled with peroxidase. With the rabbit anti-E. histolytica, all trophozoites present in hepatic lesions from 1-7 days post-inoculation were highly labeled. The IgG of rabbit anti-IgG of hamster intensively stained only those trophozoites present in lesions from 1-2 days post-inoculation. From day 3, the intensity and number of labeled trophozoites decreased progressively. The results suggest that the interaction between the amebas and the IgG of hamster is non-specific during the first 2 days. The absence of labeling in the chronic stages could be due to changes in the membrane antigens of the parasite or to alterations in the bloodstream around necrosis. Also, the anti-E. histolytica antibodies produced in the serum during the development of the hepatic disease are apparently incapable of reaching and interacting with the trophozoites present on the liver abscess. This can explain in part why antibodies do not have an important role in the defense of the host.

Animals↗
PubMed2000

Psychiatric symptoms related to interferon therapy for chronic hepatitis C: clinical features and prognosis.

Psychiatric symptoms during interferon (IFN) therapy for viral hepatitis have been a crucial problem in consultation-liaison psychiatry. However, there have been few studies on psychiatric management for these symptoms and their prognosis. Among 943 patients who were treated with IFN for chronic hepatitis C between 1991 and 1995, 43 patients (4.6%) developed psychiatric symptoms during IFN treatment. Three patients (0.3%), with pre-existing psychiatric disorders showed aggravated symptoms and were excluded from the study. All three patients were able to finish the IFN therapy with psychiatric management. Forty patients (4.2%) manifested psychiatric symptoms induced by IFN. Thirteen patients (1.4%) were diagnosed as anxiety disorder and 21 patients (2.2%) revealed mood disorder with depressive features. There were other psychiatric disorders in six patients (0.6%), including psychotic disorder with delusions/hallucinations in four patients (0.4%), mood disorder with manic features in one patient (0.1%) and delirium in one patient (0.1%). Women developed psychiatric symptoms significantly more than men. Ten of 40 patients (25%) stopped IFN treatment because of manifesting psychiatric symptoms induced by IFN. Twelve patients (30%) required psychiatric treatment for more than 24weeks after ceasing IFN, and seven patients still had anxiety, insomnia and mild hypothymia at the end of the present study. Statistical analysis revealed that IFN-beta therapy and psychiatric manifestations including psychotic symptoms, delirium and manic symptoms were significantly related to long-term psychiatric problems. There are considerable numbers of patients who have required long-term psychiatric management even after cessation of IFN treatment.

Adult↗
PubMed2000

Technetium tin colloid test detecting symptomless dysphagia and ACE inhibitor prevented occurrence of aspiration pneumonia.

Symptomless dysphagia and swallowing disorders play a very important role in the pathogenesis of aspiration pneumonia. A videofluoroscopic examination and a simple two-step swallowing provocation test (STS-SPT) could be useful for detection of swallowing disorders in elderly patients with stroke, however, there is no report on such a test for detection of symptomless dysphagia. We administered 1 ml Technetium Tin Colloid (99mTC) to the patient during sleep via a nasal catheter placed in the mouth. At 09:00 h the next day, symptomless dysphagia was checked for by imaging. Improvement of the symptomless dysphagia was observed, and thus we could prevent the occurrence of aspiration pneumonia. The 99mTC test was particularly useful in detecting symptomless dysphagia in elderly patients with stroke.

Aged↗
PubMed2000

Immunohistochemical expression of glutathione transferase-pi in untreated primary non-small-cell lung cancer.

Patients with unresectable non-small-cell lung cancer (NSCLC) usually have undergone chemotherapy; however, such problems as resistance to chemotherapeutic agents occur during the treatments. Recent studies have indicated that glutathione S-transferase-pi (GST-pi) may play an important role in the resistance of cancer cells to alkylating agents, including cisplatin compounds. We examined a possible relationship between immunohistochemical expression of GST-pi and the response to cisplatin plus etoposide chemotherapy in patients with untreated and unresectable primary NSCLC. Of the 89 patients, 50 (56.2%) were GST-pi-positive and 39 (43.8%) were GST-pi-negative. For the patients with negative GST-pi expression, the response rate was 66.7% (26 of 39 patients). In the patients with positive GST-pi expression, the response rate was 26% (13 of 50 patients). This difference was statistically significant (P = .0019). The results suggest that GST-pi expression in NSCLC tissues is related to response to cisplatin plus etoposide chemotherapy and may be useful as a predictor of chemotherapy response.

Adenocarcinoma↗
PubMed1999

Direct agonists for serotonin receptors enhance locomotor function in rats that received neural transplants after neonatal spinal transection.

We analyzed whether acute treatment with serotonergic agonists would improve motor function in rats with transected spinal cords (spinal rats) and in rats that received transplants of fetal spinal cord into the transection site (transplant rats). Neonates received midthoracic spinal transections within 48 hr of birth; transplant rats received fetal (embryonic day 14) spinal cord grafts at the time of transection. At 3 weeks, rats began 1-2 months of training in treadmill locomotion. Rats in the transplant group developed better weight-supported stepping than spinal rats. Systemic administration of two directly acting agonists for serotonergic 5-HT(2) receptor subtypes, quipazine and (+/-)-1-[2, 5]-dimethoxy-4-iodophenyl-2-aminopropane), further increased weight-supported stepping in transplant rats. The improvement was dose-dependent and greatest in rats with poor to moderate baseline weight support. In contrast, indirectly acting serotonergic agonists, which block reuptake of 5-HT (sertraline) or release 5-HT and block its reuptake (D-fenfluramine), failed to enhance motor function. Neither direct nor indirect agonists significantly improved locomotion in spinal rats as a group, despite equivalent upregulation of 5-HT(2) receptors in the lumbar ventral horn of lesioned rats with and without transplants. The distribution of immunoreactive serotonergic fibers within and caudal to the transplant did not appear to correspond to restoration of motor function. Our results confirm our previous demonstration that transplants improve motor performance in spinal rats. Additional stimulation with agonists at subtypes of 5-HT receptors produces a beneficial interaction with transplants that further improves motor competence.

Amphetamines↗
PubMed1999

Cerebral blood flow regulation under activation of the primary somatosensory cortex during electrical stimulation of the forearm.

Coupling of neuronal activity to cerebral blood flow (CBF) is widely accepted, but the exact mechanism is still under investigation. We assessed the responses of CBF coupled with electrical activity over the primary somatosensory cortex (S-I) during electrical stimulation of the contralateral forearm in cats. CBF in S-I was monitored using laser-Doppler flowmetry (LDF), and electrical activity was recorded with a tungsten microelectrode. The effects of varying stimulus intensity and frequency were examined to assess the optimal stimulation parameters. CBF increased within 10 sec after onset of stimulation, sustained the plateau level, and returned to the pre-stimulus level after cessation of stimulation. The maximum response was obtained at 4 Hz under a constant intensity. Optimal stimulus intensity at 4 Hz ranged from 8 to 10 V. At intensity higher than 10 V, CBF increases reached a near-plateau level, while mean arterial blood pressure (MABP) decreased slightly. Electrical activity was recorded at the same restricted area where CBF increased. Low frequency components of the power spectrum of electrical activity increased as the CBF increase became greater. A tight coupling of CBF increases to neuronal activation is suggested, and CBF regulation may be affected by stimulation parameters.

Animals↗
PubMed1998

Critical interval for rescue of axotomized neurons by transplants.

To determine whether embryonic spinal cord transplants retained the ability to prevent retrograde death of Clarke's nucleus (CN) neurons if supplied after a delay, we hemisected adult rats at the T8 spinal cord segment and placed transplants of fetal tissue into the hemisection cavity immediately or up to 14 days later. Transplants provided in the first 7 days after injury prevented virtually all of the 30% loss of CN neurons at L1 ipsilateral to hemisection that occurs without a transplant. Transplants supplied at 14 days post-hemisection were ineffective. Because prevention of retrograde neuron death is one mechanism by which transplants may contribute to locomotor recovery after spinal cord injury, this window of effectiveness should be considered in the design of clinical trials.

Animals↗
PubMed1998

Neurotrophin-3 prevents death of axotomized Clarke's nucleus neurons in adult rat.

In the present investigation, we studied whether neurotrophin-3 (NT-3) contributes to the rescue of axotomized Clarke's nucleus (CN) neurons in adult rats. A significant (24%) loss of CN neurons occurred at L-1 ipsilateral to T-8 hemisection by 14 days, which reached 31% at 2 months and then stabilized. Axotomized CN neurons had also atrophied by 14 days, but mean cell size did not decrease further. Animals that received gelfoam soaked in nerve growth factor, brain derived neurotrophic factor, or ciliary neurotrophic factor at the lesion site also showed a 30% neuron loss at 2 months, and a 40% reduction in average cell area. Rats receiving NT-3 showed a 15% neuron loss, which was not improved by additional neurotrophins in combination with NT-3. None of the treatments prevented neuron atrophy. Bioassay of the gelfoam showed that NT-3 bioactivity remained at 5 days after surgery but not at 14 days. Additional rats with hemisections that received NT-3 continuously via mini-pump for 2 months showed a 15% neuron loss, the same as with NT-3 given via gelfoam. These results indicate that even limited exposure of axotomized CN neurons to NT-3 produces permanent rescue of 50% of the neurons. The virtually complete rescue that we had previously observed with transplants of fetal central nervous system (CNS) tissues may, therefore, be due at least in part to NT-3, but the exogenous administration of a single neurotrophic factor or a combination of neurotrophic factors is less effective than transplants in producing long-term survival of axotomized CNS neurons.

Animals↗
PubMed1998

Entamoeba histolytica: liver invasion and abscess production by intraperitoneal inoculation of trophozoites in hamsters, Mesocricetus auratus.

Intraperitoneal inoculation of axenically cultured Entamoeba histolytica trophozoites constitutes an easy to perform, highly reproducible procedure for inducing amebic liver abscesses in hamsters. Efficiency in abscess production (95% of infected animals after 1 week) was similar to data reported using direct intrahepatic or intraportal inoculation. The morphological sequence of infection shows that amebas in the peritoneal cavity initially produce a large exudate constituted mainly of acute inflammatory cells. These cells form a rim of polymorphonuclear leukocytes surrounding the amebas, which adhere to the trophozoite and can sometimes be observed polarized to one end of the parasite, suggesting capping of surface receptors. Early stages are also characterized by the production of distant inflammatory reactions in the hepatic portal spaces. At 6 h postintraperitoneal inoculation, larger foci of inflammatory reactions surrounding amebas are developed in the peritoneum, extending to and damaging the liver surface membranes as well as the serosa of other internal organs. Thereafter, tissue damage progresses deeper into the liver parenchyma, and a few days later, coalescing granulomas and large necrotic areas are observed in the liver tissue. Based on the present morphological time-sequence study, we suggest that inflammatory cells associated with E. histolytica trophozoites play an important role in commencing the damage of liver sheaths and producing the subsequent parenchymal lesions. The simplicity and reliability of this model are important factors to consider when large numbers of experimentally induced amebic liver abscesses are needed.

Animals↗
PubMed1998

Fetal transplants rescue axial muscle representations in M1 cortex of neonatally transected rats that develop weight support.

Fetal transplants rescue axial muscle representations in M1 cortex of neonatally transected rats that develop weight support. J. Neurophysiol. 80: 3021-3030, 1998. Intraspinal transplants of fetal spinal tissue partly alleviate motor deficits caused by spinal cord injury. How transplants modify body representation and muscle recruitment by motor cortex is currently largely unknown. We compared electromyographic responses from motor cortex stimulation in normal adult rats, adult rats that received complete spinal cord transection at the T8-T10 segmental level as neonates (TX rats), and similarly transected rats receiving transplants of embryonic spinal cord (TP rats). Rats were also compared among treatments for level of weight support and motor performance. Sixty percent of TP rats showed unassisted weight-supported locomotion as adults, whereas approximately 30% of TX rats with no intervention showed unassisted weight-supported locomotion. In the weight-supporting animals we found that the transplants enabled motor responses to be evoked by microstimulation of areas of motor cortex that normally represent the lumbar axial muscles in rats. These same regions were silent in all TX rats with transections but no transplants, even those exhibiting locomotion with weight support. In weight-supporting TX rats low axial muscles could be recruited from the rostral cortical axial representation, which normally represents the neck and upper trunk. No operated animal, even those with well-integrated transplants and good weight-supported locomotion, had a hindlimb motor representation in cortex. The data demonstrate that spinal transplants allow the development of some functional interactions between areas of motor cortex and spinal cord that are not available to the rat lacking the intervention. The data also suggest that operated rats that achieve weight support may primarily use the axial muscles to steer the pelvis and hindlimbs indirectly rather than use explicit hindlimb control during weight-supported locomotion.

Animals↗
PubMed1998

[Effects of closed-circuit breathing apparatus on respiration and metabolism].

The purpose of the study was to evaluate the influence of hyperoxia and hypercapnia on respiration and metabolism during a steady-state exercise. Thirteen healthy subjects were examined during bicycle-ergometer rides at approximately 50% VO2max under four different breathing gas conditions: 1) room air (control); 2) 40% oxygen; 3) 3% carbon dioxide; 4) 40% oxygen and 3% carbon dioxide. Hyperoxia, with or without hypercapnia, decreased respiratory ventilation and carbon dioxide elimination significantly. On the other hand, oxygen uptake in hyperoxia was not significantly different from that of normoxia. Hypercapnia increased respiratory ventilation more than 30% compared to normocapnia, but it did not change oxygen uptake and carbon dioxide elimination significantly.

Adult↗
PubMed1998

Bronchial asthma induced by rice.

A 43-year-old patient with rice-induced bronchial asthma was first admitted to our hospital for developing bronchial asthma induced by mite and house dust. At that time, there was no sign of allergic response to rice. Two years later, he was readmitted in an emergency state, with a severe attack of bronchial asthma. This time, however, the result of immunoglobulin E (IgE)-radioallergosorbent test (RAST) for rice was positive, with those to mite and house dust were unexpectedly negative. The causative factors and pathological mechanisms of various kinds of food allergies still remain unknown. The patient is now followed up in an ambulatory setting, and has been eating hypoallergenic rice with no bronchial asthma-induced attack. The present case, being an adult patient with severe grain-induced bronchial asthma previously allergic to mite and house dust, seems to be rather rare in the literature.

Adult↗