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Biomedical subjects

M Koga

Publications and source records attributed to M Koga.

At least 91 records · Page 5Linked to original sources
PubMed2001

[Experience of four cases of postoperative pulmonary embolism requiring surgical treatment].

Four patients underwent a pulmonary embolectomy using cardiopulmonary bypass for acute pulmonary embolism which had occurred after various operations. In two cases, dehydration due to either diabetes insipidus or ileus had existed. In two cases, pulmonary embolism suddenly occurred in our hospital. In the remainder, the disease occurred in the previous hospitals and its diagnosis was established on the 6th and 7th postoperative days, respectively. In massive pulmonary embolism, echocardiography and/or enhanced chest CT are useful for prompt and noninvasive diagnosis. Thrombolytic therapy was performed in only one case before surgical embolectomy, which was not effective. Three patients were discharged without any postoperative complications, but one requiring preoperative external cardiac massage died of multiple organ failure 9 days after operation. Acute pulmonary embolism is one of the fatal postoperative complications. Recognition of this entity, and prompt diagnosis and treatment are essential for managing the fatal disease. Even in the early postoperative period, embolectomy using cardiopulmonary bypass is a safe and effective treatment.

Acute Disease↗
PubMed2001

Animal model of axonal Guillain-Barré syndrome induced by sensitization with GM1 ganglioside.

Some humans develop the axonal form of Guillain-Barré syndrome after receiving bovine brain ganglioside. On sensitization with the ganglioside mixture, all of a group of rabbits injected developed high anti-GM1 IgG antibody titers, flaccid limb weakness of acute onset, and a monophasic illness course. Pathological findings for the peripheral nerves showed predominant Wallerian-like degeneration, with neither lymphocytic infiltration nor demyelination. IgG was deposited on the axons of the anterior roots, and GM1 was proved to be present on the axons of peripheral nerves. Sensitization with purified GM1 also induced axonal neuropathy, indicating that GM1 was the immunogen in the mixture. A model of human axonal Guillain-Barré syndrome has been established that uses inoculation with a bovine brain ganglioside mixture or isolated GM1. This model may help to clarify the molecular pathogenesis of the syndrome and to develop new treatments for it.

Animals↗
PubMed2001

Runoff of acidic substances that originated from atmospheric deposition on Yakushima Island, a world natural heritage site.

In this paper we present monitoring data of stream waters that may reflect acidic impacts on the island as well as the rainwater qualities. The pH ranges of the river water in the Kawara streams in the western part of the island and the Yodogo stream in the central part of the island were 5.71-6.35 and 5.85-6.12 during 1992-1999, respectively. The concentrations of SO4(2-) and NO3- in the river water were lower than those in the rainwater. Many differences were observed among the sampling sites. Higher concentrations of acid substances are found in the stream waters of the western area compared to the other areas. On the other hand, sulfuric acid is the major acid in the rainwater, snow and rime ice. No differences were observed in the ion constituents of the rainwater collected in the areas. These results suggested that the densely growing canopy may play a role in holding air pollutants, and acidic substances deposited on the canopy would be discharged as a through-fall and a stem flow. Furthermore, the water mass containing high ionic substances in the western area has been held in the groundwater layer, continuously supplying the stream waters during dry weather days. On the other hand, part of the basic runoff will be diluted with a surface runoff during the rainy days. As a result, the concentrations of the ionic substances in the stream waters during rainy days decreased.

Acid Rain↗
PubMed2001

[A case of brainstem encephalitis associated with Epstein-Barr virus infection: differentiation of acute disseminated encephalomyelitis and Bickerstaff's brainstem encephalitis].

A 28-year-old woman initially suffered high fever and headache (day 1). Aseptic meningitis was diagnosed on day 3. Limb ataxia, however, appeared on day 7, and external ophthalmoplegia and drowsiness were recognized on day 8. Urinary disturbance and orthostatic hypotension appeared on day 13. Cerebrospinal fluid showed moderately high cell counts(mononuclear cells, 51/microliter; polynuclear cells, 9/microliter). MRI T2-weighted images showed high intensity lesions in the pons and mesencephalon. No serum anti-GQ1b IgG antibody was detected on day 4. Epstein-Barr virus (EBV) viral capsid antigen-IgG antibody was positive, and EBV determined nuclear antigen antibody was seroconverted. EBV-DNA was detected in the CSF by PCR. These findings indicate prior infection by EBV. After intravenous dexamethasone therapy, these symptoms rapidly disappeared. Our patient showed external ophthalmoplegia, ataxia, and disturbance of consciousness, which are the cardinal signs in Bickerstaff's brainstem encephalitis. The time course of her neurological symptoms, the presence of meningitis, and the MRI findings, however, indicated the pathogenesis of acute disseminated encephalomyelitis rather than Bickerstaff's brainstem encephalitis. We diagnosed this patient as a brainstem encephalitis associated with EBV infection.

Adult↗
PubMed2001

A case of proliferative fasciitis in the abdominal region.

A 20-year-old woman complained of a subcutaneous nodule accompanied by spontaneous pain and tenderness in the right hypochondriac region approximately two weeks prior to initial evaluation. The spontaneous pain and tenderness gradually worsened. Histopathological examination revealed a proliferative lesion that extended from the deep dermis to the fatty tissue and consisted predominantly of stellate or spindle-shaped fibroblast-like cells intermingled with gangliocyte-like giant cells. Consequently, proliferative fasciitis was diagnosed. Our investigation revealed only 19 cases of proliferative fasciitis reported in Japan. The overall age range of them is 20 to 75 years (mean, 57.6 years). The lesion site in them is the head and neck in 10%, the trunk in 30%, and the extremities in 60%. It follows that the extremities are predominantly the site of proliferative fasciitis, and truncal lesions are relatively rare. It is rare for proliferative fasciitis to occur at a young age or in the abdominal region. We therefore examined the differences between proliferative fasciitis and similar disorders, namely proliferative myositis and nodular fasciitis, based on summaries of cases reported in Japan.

Abdomen↗
PubMed2001

[Anti-GQ1b IgG-negative case of overlapping Fisher's and Gullain-Barré syndromes after Campylobacter jejuni (PEN 19) enteritis].

We described a 70-year-old woman with overlapping Fisher's syndrome (FS) and Guillain-Barré syndrome (GBS), from whom Campylobacter jejuni had been isolated. In typical FS as well as GBS with ophthalmoplegia and acute ophthalmoparesis without ataxia, serum anti-GQ1b IgG antibody often is detected and ophthalmoplegia is characterized by the predominant abducens palsy. This patient, however, showed marked oculomotor nerve disturbance. Serum anti-GQ1b IgG antibody was negative and IgG antibodies against GM1, GM1b, and GD1a were strongly positive. Although FS and overlap of FS/GBS have been reported to be associated with PEN2 of C. jejuni, the isolate from our case belonged to PEN 19. C. jejuni serotype may be associated with clinical manifestations and anti-ganglioside antibody species.

Aged↗
PubMed2000

A Caenorhabditis elegans MAP kinase kinase, MEK-1, is involved in stress responses.

The c-Jun N-terminal kinase (JNK), a member of the mitogen-activated protein kinase (MAPK) family, was shown to be involved in the response to various stresses in cultured cells. However, there is little in vivo evidence indicating a role for a JNK pathway in the stress response of an organism. We identified the Caenorhabditis elegans mek-1 gene, which encodes a 347 amino acid protein highly homologous to mammalian MKK7, an activator of JNK. Mek-1 reporter fusion proteins are expressed in pharyngeal muscle, uterus, a portion of intestine, and neurons. A mek-1 deletion mutant is hypersensitive to copper and cadmium ions and to starvation. A wild-type mek-1 transgene rescued the hypersensitivity to the metal ions. Double mutants of mek-1 with an eat-5, eat-11 or eat-18 mutation, which are characterized by a limited feeding defect, showed distinct growth defects under normal conditions. Expression of an activated form of MEK-1 in the whole animal or specifically in the pharynx inhibited pharyngeal pumping. These results suggest a role for mek-1 in stress responses, with a focus in the pharynx and/or intestine.

Amino Acid Sequence↗
PubMed2000

Strongyloides ratti: thermokinetic behavior of third-stage larvae on a temperature gradient.

We examined the thermokinetic behaviors of infective third-stage larvae (L3) of the rodent parasitic nematode Strongyloides ratti on temperature gradients using an in vitro agarose tracking assay method. Observed behaviors included both negative and positive thermokineses, the direction of movement depending both on the gradient temperature at which larvae were initially placed and on prior experience of culture temperature. Larvae isolated from rat feces cultured at 25 degrees C and placed on a gradient at temperatures between 22 degrees and 29 degrees C tended to move toward higher temperatures. At higher placement temperatures, most larvae moved little and showed no directional response, whereas at lower placement temperatures, many migrated toward cooler temperatures. At placement temperatures of 20 degrees C or below, few or no larvae moved toward the zone of higher temperature. Larvae isolated from rat feces cultured at 20 degrees C tended to migrate to a high temperature area regardless of placed temperature. Those cultured at 30 degrees C did not respond to the temperature gradient. L3 cultured at 30 degrees C were significantly less infective to rats than those cultured at 25 degrees or 20 degrees C. Additional experiments were designed to demonstrate thermokinetic behaviors during the period after reaching the L3 stage. Larvae incubated in double distilled water (DDW) for 24 h at 37 degrees C lost their ability to respond to lower temperatures, while in those incubated in DDW at 15 degrees and 25 degrees C, responses were still apparent. The thermokinetic behavior of S. ratti L3 is affected by surrounding environmental temperatures and this may have an important role in host finding.

Animals↗
PubMed2000

Effects of various treatments on the chemokinetic behavior of third-stage larvae of Strongyloides ratti on a sodium chloride gradient.

In observations of the movements of the infective third-stage larvae of a rodent parasitic nematode, Strongyloides ratti, on a sodium chloride gradient set up on agarose plates, two types of chemokinetic behavior were seen: a unidirectional avoidance movement on initial placement of the larvae in unfavorable environmental conditions and a random dispersal movement on their placement within an area of favorable conditions. Track patterns were straight in the avoidance movement but included multiple changes of direction and loops in the dispersal movement. In the present study we examined the interventional activity of treatment with various enzymes, lectins, and chemicals by analyzing the unidirectional avoidance movements of the larvae. We observed that beta-glucosidase, hyaluronidase, beta-galactosidase, trypsin, protease, lipase, phospholipase C, soybean agglutinin, wheat germ agglutinin, and spermidine exerted inhibitory actions on those movements, which may be guided by the chemosensory function of this nematode.

Animals↗
PubMed2000

Experimental exposure of rat skin to methyl bromide: a toxicokinetic and histopathological study.

Methyl bromide was experimentally exposed to a 12 cm2 area of the back skin of Wistar rats for 30 s, and for 1, 3, and 5 min, and time courses of both changes in plasma bromide concentration and of histopathological changes were examined. To measure bromide ion, a head space gas chromatography was used. The concentration of plasma bromide ion showed a sharp increase immediately after the exposure in all exposed groups, reaching a peak level after 1 h, then decreased rapidly. The ion level gradually decreased after 72 h to 1 week, and returned to a normal level after 4 to 8 weeks. Calculating from a regressive curve, the biological half lives of plasma bromide ion were 5.0 days to 6.5 days. Histopathologically, the impairments to the epidermal cells, fibroblasts and blood vessels were observed in the early phase. These cellular changes could be due to the direct cytotoxicity of the compound. In the next phase, newly infiltrating cells showed degeneration and necrosis. Subsequently, an impairment of the collagen bundles was observed. Our experiments suggested an immediate permeation and rapid metabolization of methyl bromide in the skin and a multistep formation of the skin damage induced by the compound. These processes of methyl bromide-induced skin damage are quite different from chemical skin injuries caused by the representative causative agents such as alkaline and acid.

Animals↗
PubMed2000

Estrogen deficiency is a potential cause for osteopenia in adult male patients with Noonan's syndrome.

Osteopenia is frequently observed in patients with Turner's syndrome. By contrast, there is no report concerning bone metabolism in patients with Noonan's syndrome which comprises Turner's phenotypic characteristics without any sex chromosome abnormalities. In the present investigation, we determined bone mineral density (BMD) as well as serum and urine indices of bone turnover in two male patients with Noonan's syndrome. Both patients showed remarkably decreased BMD, measured at two sites on the lumbar spine (L2-L4) and the distal end of the radius using dual energy X-ray absorptiometry (DXA). Urinary pyridinoline (PYD) and deoxypyridinoline (DPD) concentrations were significantly elevated in both patients, and serum osteocalcin and carboxyterminal propeptide of type I procollagen (PICP) concentrations were elevated in one patient. Surprisingly, both patients had a low level of serum 17beta-estradiol compared with control males, whereas they had normal levels of serum testosterone and dihydrotestosterone. Conjugated estrogens (Premarin 0.625 mg/day) were continued to be administered to these patients, followed up for 12 months. Urinary PYD and DPD concentrations gradually decreased, followed by an increase in their BMD. This is the first report that male patients with Noonan's syndrome showed osteopenia associated with increased bone resorption. Our data indicate that hypoestrogenism plays a potentially significant role in the abnormal bone metabolism in these patients.

Adolescent↗
PubMed2000

The crucial role of granulocytes in the early host defense against Strongyloides ratti infection in mice.

The involvement of granulocytes in the host early defense against the nematode, Strongyloides ratti, was studied. It was confirmed that granulocytes were effectively depleted for 4 days by anti-granulocyte monoclonal antibody (anti-Gr-1). To examine the involvement of granulocytes in the host defense against migrating larvae, 2,000 S. ratti infective larvae (L3) were inoculated subcutaneously 1 day after antibody treatment. The number of S. ratti eggs secreted in feces (EPG) was higher in the granulocyte-depleted group than in the control group. The number of migrating larvae also increased in the granulocyte-depleted group in accordance with the increase in EPG. Therefore granulocytes are crucial for the host early defense against migrating larvae of S. ratti. Next, the involvement of granulocytes in the intestinal early defense was examined. Mice were treated with the antibody on day 3 post-infection. On that day, almost all inoculated larvae reached the intestine and molted to become adults. EPG on day 5 post-infection was increased by the antibody treatment, but no effect was observed on intestinal worm numbers. The fecundity (EPG/worm number) of S. ratti adult worms in the granulocyte-depleted group was higher than that in the control group. Thus granulocytes are also involved in the intestinal early defense through suppressing fecundity of the adult worms. On the other hand, the depletion of granulocytes had no effect on the late adaptive response against S. ratti adult worms (e.g. number of intestinal mucosal mast cells, time of worm expulsion). These results suggest that granulocytes are mainly involved in the host early defense against parasites.

Animals↗
PubMed2000

Prospective analysis of risk factors for early intrahepatic recurrence of hepatocellular carcinoma following ethanol injection.

BACKGROUND/AIM: Time-dependent intrahepatic recurrence of hepatocellular carcinoma is frequent after different treatment modalities, including percutaneous ethanol injection. We attempted to prospectively analyze the possible risk factors for early intrahepatic recurrence of hepatocellular carcinoma after percutaneous ethanol injection. METHODS: Sixty-five patients with 65 solitary hepatocellular carcinoma nodules < or =6 cm in diameter underwent initial treatment with percutaneous ethanol injection and were examined to ascertain the factors related to recurrence, local and distant, within the liver. A number of clinical and tumor parameters were analyzed. RESULTS: Cumulative overall recurrence rates 12 and 24 months after percutaneous ethanol injection were 15.6% and 45.1%, respectively, irrespective of clinical and tumor parameters. Overall recurrence rates 12 and 24 months after percutaneous ethanol injection were 40% and 67.5%, for tumor > or =3 cm and 7.5% and 37.5%, for tumor <3 cm. Cumulative local recurrence rates at 12 and 24 months were 26.3% and 43.5%, respectively, for tumor > or =3 cm and 11.7% and 18.2%, respectively, for tumor <3 cm. The log-rank test indicated that a tumor size of > or =3 cm and the presence of capsule for a tumor of <3 cm in diameter were significant risk factors for intrahepatic recurrence. A pretreatment serum PIVKA-II level of > or =0.02 AU/ml was the only clinical parameter associated with overall recurrence (p=0.0041) and distant intrahepatic recurrence (p=0.0307). Distant intrahepatic recurrence rates 12 and 24 months after percutaneous ethanol injection were 22.5% and 31.4%, respectively, for PIVKA-II levels of > or =0.02 AU/ml and 8% and 17.8%, for PIVKA-II of <0.02 AU/ml. Cox's proportional hazard model identified that tumor size, tumor capsule and baseline serum PIVKA-II levels were independently related to intrahepatic recurrence. CONCLUSIONS: These data demonstrate that tumor size and peritumoral capsule were associated with overall and local recurrence of hepatocellular carcinoma. Moreover, pretreatment serum levels of PIVKA-II can indicate the risk of early intrahepatic recurrence and may assist in patient selection and appropriate therapy.

Adult↗
PubMed2000

MR imaging of radiation osteitis in the sacroiliac joints.

The purpose of this study was to analyze magnetic resonance (MR) images of radiation osteitis of sacroiliac joints, retrospectively. Seven patients with radiation osteitis, which was diagnosed by pelvic plain radiographs and CT images, underwent MRI. T(1)-weighted spin echo images and T(2)-weighted fast spin echo images were obtained in all patients. Four patients were examined after gadolinium injection. Major signal changes of radiation osteitis were distributed on the iliac side. T(1)-weighted images showed diffuse low intensity both in sacral and iliac sides. T(2)-weighted images showed very low intensity adjacent to sacroiliac joints, but mixed intensity was illustrated apart from joints, and high intensity in the peripheral areas. Radiation osteitis showed slight to mild, but irregular enhancement in four patients after gadolinium administration. MRI can illustrate abnormal bone change distribution and is useful for diagnosing this entity by characteristic intensity patterns on T(1)-weighted images with and without gadolinium and T(2)-weighted image. However, the diagnosis of accompanied insufficiency fractures in the area of radiation osteitis is occasionally difficult with conventional MRI.

Aged↗
PubMed2000

Chemokinetic behavior of the infective third-stage larvae of Strongyloides ratti on a sodium chloride gradient.

The movements of the infective third-stage larvae (L3) of a rodent parasitic nematode Strongyloides ratti were examined on a sodium chloride (NaCl) gradient set up on agarose plates. The movements of larvae were followed by observing their tracks on the surface of the agarose. The direction of movement depended on the NaCl concentration at the point of their initial placement on the gradient. Larvae placed at between 230 and 370 mM NaCl tended to migrate towards areas of lower concentration. On the other hand, when placed at concentrations less than 20 mM NaCl, larvae tended to migrate initially towards higher concentrations but did not linger in areas where the concentration was over approximately 80 mM NaCl. It seems that S. ratti L3, tested in vitro, prefer regions with a concentration of NaCl below 80 mM NaCl. Two typical chemokinetic behaviors are seen; a unidirectional avoidance movement when initially placed in unfavorable environmental conditions and a random dispersal movement when placed within an area of favorable conditions. Track patterns were straight in the avoidance movement but included multiple changes of direction and loops in the dispersal movement. This study introduces an assay system suitable for studying chemokinetic behavior of larvae of Strongyloides ratti.

Animals↗
PubMed2000

Detection of HBV RNA in peripheral blood mononuclear cells in patients with and without HBsAg by reverse transcription polymerase chain reaction.

We examined RNA of hepatitis B virus (HBV) in peripheral blood mononuclear cells (PBMCs) by the reverse transcription polymerase chain reaction (RT PCR) in 61 patients associated with HBV infection, in order to analyze the relationship between the transcriptional activity of HBV in PBMCs and the clinical characteristics. The presence of HBV RNA in PBMCs was detected in 19/51(37.1%) patients with HBsAg positive and in 1/10 (10.0%) patient with HBsAg negative patients. Six healthy controls were all negative. The frequency of HBV RNA positivity was detected in patients with high ALT level (P<0.05), serum HBeAg positivity (P<0.01) and serum HBV DNA level>/=0.7 Meq/ml (P<0.05). Moreover, HBV RNA in PBMCs was detected in one patient followed up for 2 years after HBsAg disappearance in serum, who had not HBV DNA but anti-HBc IgG, in serum. These results suggested that the transcription of HBV in PBMCs, was frequently detected in the patients with higher replication of the virus, but HBV RNA in PBMCs might be detected in a few patients who had no evidence of HBV replication serologically.

Journal Article↗