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Biomedical subjects

K Hamaya

Publications and source records attributed to K Hamaya.

At least 19 recordsLinked to original sources
PubMed2005

Mixed magnetic phases in (Ga,Mn)As epilayers.

Two different ferromagnetic-paramagnetic transitions are detected in (Ga,Mn)As/GaAs(001) epilayers from ac susceptibility measurements: transition at a higher temperature results from (Ga,Mn)As cluster phases with [110] uniaxial anisotropy and that at a lower temperature is associated with a ferromagnetic (Ga,Mn)As matrix with 100 cubic anisotropy. A change in the magnetic easy axis from [100] to [110] with increasing temperature can be explained by the reduced contribution of 100 cubic anisotropy to the magnetic properties above the transition temperature of the (Ga,Mn)As matrix.

Journal Article↗
PubMed2001

Plaque-like structures and arteriosclerotic changes in "diffuse neurofibrillary tangles with calcification" (DNTC).

"Diffuse neurofibrillary tangles with calcification" (DNTC) is a rare form of slowly progressive dementia characterized by temporal or fronto-temporal atrophy with neuronal loss and astrocytosis, neurofibrillary tangles and Fahr-type calcification, but no senile plaques in the cerebral cortex. In patients with DNTC, we detected a novel histopathological abnormality that we termed "plaque-like structures" (PLS). PLS appeared as oval, slightly eosinophilic masses of up to 100 microns in diameter. With methenamine silver stain, the PLS were argyrophilic, and thread-like structures were observed in and around them. Most PLS were observed in deep layers of the cortex and subcortical white matter, and were accompanied by small vessels. They were intimately associated with the small-vessel walls and astrocytes. They were composed of two types of fibers. The first type comprised straight and loosely interwoven fibers about 25-30 nm in diameter, while the other type evoked tangles. These structures have not been found in other neurodegenerative diseases, including Alzheimer's disease. In addition, to evaluate hyaline arteriosclerosis in DNTC, we examined sclerotic changes of the medullary arteries and assessed white matter lesions in affected patients. In three of four patients with DNTC, sclerosis of the medullary arteries was significantly more extensive than in age-matched controls. In all four patients, the severity of white matter lesions was graded as moderate or severe in the temporal lobe and as mild or moderate in the frontal lobe. Arteriosclerotic changes and white matter lesions can occur without hypertension and beta amyloid deposits in DNTC.

Amyloid beta-Peptides↗
PubMed2001

Basaloid-squamous cell carcinoma of the esophagus: diagnosis based on immunohistochemical analysis.

Basaloid-squamous cell carcinoma of the esophagus (BSCC) is an extremely rare tumor. Histologically, this tumor should be differentiated from adenoid cystic carcinoma (ACC) and small cell undifferentiated carcinoma (SCUC). Biologically, this tumor is very aggressive, with a propensity for distant metastasis. We report a 64-year-old male with esophageal BSCC. The patient complained of dysphagia and was found to have a torous lesion in the esophagus on radiological examination. Upper gastrointestinal fiberscopy showed a localized ulcerative type tumor, which was diagnosed as squamous cell carcinoma (SCC) on biopsy. Surgery resulted in curative resection. A histological examination of the resected tumor showed features of BSCC. Immunohistochemical examination demonstrated AE3/1- and CAM 5.2-positive tumor cells, and laminin-positive cells in the periphery of the nests. These data were useful in differentiating this tumor from ACC and SCUC. Six months after surgery, the patient developed hepatic metastases, which were successfully treated by regional chemotherapy via the hepatic artery by using fluorouracil. The patient is currently being followed up at the outpatient clinic and shows no signs of any recurrence.

Biomarkers↗
PubMed1998

Deletion of Epstein-Barr virus latent membrane protein 1 gene in Japanese and Brazilian gastric carcinomas, metastatic lesions, and reactive lymphocytes.

A 30-bp deletion in the Epstein-Barr virus (EBV) latent membrane protein 1 (LMP1) gene has been reported in nasopharyngeal carcinoma and EBV-associated malignant lymphomas. Information on this deletion in EBV-associated gastric carcinoma (EBVaGC) is limited. The association of gastric carcinoma (GC) with EBV was examined by EBV-encoded RNA (EBER) in situ hybridization in 510 patients from Japan and 80 patients from Brazil. We studied the prevalence of 30-bp LMP1 gene deletion in EBVaGC in Japan (29 cases) and Brazil (four cases) in comparison with the corresponding EBER1-positive metastatic lesions in lymph nodes (10 cases) and EBV-infected reactive lymphocytes from dissected nonmetastatic lymph nodes (22 cases), microdissected non-neoplastic gastric mucosa of EBVaGC (five cases), and EBV-nonassociated GC (25 cases). We studied the status of the LMP1 gene by Southern blot hybridization of polymerase chain reaction products obtained after amplification with primers flanking the site of the deletion. We also performed EBV typing and LMP1 protein immunohistochemistry. EBV DNA was amplified by polymerase chain reaction in 30 of 33 EBVaGC cases, 8 of 10 metastatic carcinomas, 14 non-neoplastic tissues from 27 EBVaGC cases, and 12 of 25 non-EBV-associated GC cases with EBER1-positive lymphocytes. The 30-bp LMP1 gene deletion was observed in 23 of 26 (88.5%) cases of EBVaGC from Japan and two of four (50%) cases of Brazilian EBVaGC as compared with EBER1-positive reactive lymphocytes from 11 of 14 (78.6%) EBVaGC cases and 9 of 12 (75%) cases of non-EBV-associated GC. The variant type (the 30-bp deletion variant or nondeleted wild type) of LMP1 gene was the same among reactive lymphocytes, primary and secondary lesions of EBVaGC in all cases for which all three tissue types were studied (six of six). There was no correlation between the presence of the 30-bp deletion with depth of cancer invasion or presence of metastasis. Type A was detected in all available EBV-positive cases. The similar high incidence of 30-bp deletion in LMP1 gene in both carcinoma cells and reactive lymphocytes in EBVaGC cases suggests that this deletion may not be relevant to the pathogenesis of EBVaGC.

Adult↗
PubMed1997

Epithelial hyperplasia of the larynx a clinical follow-up study.

In this retrospective study, the records of 40 patients with epithelial hyperplasia of the larynx, seen between 1980-1991, were reviewed to determine the incidence of malignant transformation during long term follow-up. The mean follow-up time was 58.6 months. The initial pathological diagnoses were hyperkeratosis in one case, parakeratosis in one, dyskeratosis in 12 and dysplasia in 26. During follow up, nine patients developed carcinoma in situ and/or invasive carcinoma. Of these, two patients had been diagnosed with dyskeratosis without dysplastic cells at the initial biopsy. It is therefore important to follow up patients with epithelial hyperplasia of the larynx even when no dysplastic cells are found at the time of diagnosis.

Adult↗
PubMed1996

A case of traumatic neuroma of the gallbladder in the absence of previous surgery and cholelithiasis.

We experienced a patient with traumatic neuroma of the gallbladder with no history of gallbladder surgery or cholelithiasis. A 74-year-old man was referred to our department after a gallbladder tumor was incidentally discovered during a preoperative screening examination for prostate hypertrophy. Ultrasonography, MRI, CT and endoscopic retrograde cholangiography revealed a protuberant lesion of the gallbladder. Laparoscopic cholecystectomy was attempted but adhesion between the liver and duodenum forced us to convert to open laparotomy. Cholecystectomy and adjacent liver tissue resection was performed. Diagnosis was made by frozen histology during operation. It revealed no malignancy. Postoperative pathological examination revealed traumatic neuroma associated with inflammation. To our knowledge, this is the first reported case of gallbladder neuroma without a history of gallstones or surgery in the English and Japanese literature since 1980. This traumatic neuroma should be considered in a differential diagnosis in treating gallbladder neoplasm, even in the absence of an operative history or cholelithiasis.

Aged↗
PubMed1995

Detection of human papillomavirus type 57 in a case of inverted nasal papillomatosis in Japan.

Human papillomavirus (HPV) type 57 DNA was detected in recurrent nasal inverted papillomatosis, in a 60-year-old Japanese male, using Southern blot hybridization. HPV types 6, 11, 16 and 18 were not detectable in the papilloma. Previous studies have shown that HPV types 6, 11, 16 and 18 were mainly found in nasal papillomatosis in other laboratories but the actual detection rate of virus was low. We speculate that this low detection rate may be due to the lack of a method for detecting HPV type 57.

Blotting, Southern↗
PubMed1995

[Granulomatous angiitis of the central nervous system complicated by the syndrome of inappropriate antidiuretic hormone].

We report an autopsy case of granulomatous angiitis of the central nervous system (GANS) complicated by the syndrome of inappropriate antidiuretic hormone (SIADH). A 88-year old female was admitted because of progressive mental deterioration, fever, and vomiting. A computed tomogram disclosed bilateral periventricular lucency, and a low-density area in the right occipital lobe. Laboratory studies during her hospital stay, revealed hyponatremia, hypoalbuminemia, and increased antidiuretic hormone. Treatment with antibiotics, hypertonic saline solution, and steroids, and water restriction was ineffective, and the patient died six weeks after admission. Autopsy examination of the brain revealed slightly turbid meninges with multiple small infarctions in the corona raiata of both cerebral hemispheres. Microscopic study disclosed granulomatous inflammation with many giant cells in the walls of small and medium sized vessels, and the adventitia and media were more involved than the intima. Their lumens were narrowed, and many thrombi were observed. Extensive non-granulomatous inflammatory change was found mainly in the subarachnoid space. All of these findings were similar to the GANS firstly reported by Cravioto et al, in 1959. Since the blood vessels in the central nervous system play an important part in any inflammatory conditions and the blood vessels may be involved by bacterial, fungal, parasitic or viral meningitis, various microorganisms have been suspected as the cause of GANS, including mycoplasma, herpes zoster, herpes simplex viruses, cytomegalovirus, and human T-lymphotropic virus type III (HTLV-III). Some reported cases have been associated with Hodgkin's disease and cerebral amyloid angiopathy. We could not identify any cause in our case.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1994

Malignant melanoma of the nasal cavity.

We report a case of amelanotic melanoma arising in the nasal cavity and paranasal sinuses, that could not be positively diagnosed as malignant melanoma before the patient's death in spite of repeated biopsies both from primary and metastatic lesions, including ultrastructural examination and immunohistochemical staining for S-100 protein with usual polyclonal antibody. The patient died of rapid wide-spread dissemination of the tumor. In autopsy specimens, melanin pigment was detected, for the first time, by the Fontana's silver stain. The posthumous diagnosis of malignant melanoma was immunohistochemically confirmed for the specific antibodies, anti alpha-subunit of S-100 protein antibody and SK-46 (original antibody for melanoma made at the Department of Pathology, University of Gunma School of Medicine) from specimens obtained while alive. The application of a specific antibody for S-100 protein is recommended as useful for the diagnosis of malignant melanoma even when routine immunohistochemical procedures fail to demonstrate S-100 protein.

Aged↗
PubMed1993

Posterior interosseous nerve paralysis related to focal radial nerve constriction secondary to vasculitis.

A case of posterior interosseous nerve paralysis is reported with discussion of some characteristics that appear to distinguish it from entrapment neuropathy and neuralgic amyotrophy. The surgical implications are also discussed. More than ten similar cases have been reported, but the pathogenesis of this condition is still controversial. The patient presented with posterior interosseous nerve paralysis related to focal radial nerve constriction secondary to vasculitis in the perineurium. The constriction site was resected and the radial nerve was sutured. The patient recovered completely after 8 months.

Adult↗
PubMed1992

Effect of captopril on isoproterenol-induced cardiac hypertrophy and polyamine contents.

It is well known that isoproterenol (ISO) a nonselective beta adrenoceptor agonist induces cardiac hypertrophy. It can be assumed that, in addition to its direct cardiac effect, ISO has a cardiac trophic effect via stimulation of the renin angiotensin system. Synthesis of polyamines is facilitated in cardiac hypertrophy and polyamine levels are rapidly elevated prior to an increase in heart weight. In the present study, we investigated whether captopril (30 mg/kg body weight, daily) could attenuate cardiac hypertrophy and elevation of cardiac polyamine levels in rats, which effects were elicited by a chronic (1- or 2-weeks) and repeated administration of a small dose (0.5 mg/kg body weight) of ISO. Cardiac hypertrophy was assessed by an increase in the wet weight and RNA content of the heart. Polyamines were analyzed by HPLC. Captopril alone did not affect either heart weight/body weight ratio or cardiac contents of polyamines and nucleic acids at the end of the second week. In isoproterenol-treated rats, the above parameters, except for putrescine content on day 14, were significantly increased on both day 7 and day 14. Captopril slightly attenuated ISO-induced cardiac hypertrophy and significantly prevented the ISO-evoked increase in the contents of RNA, spermidine, and spermine at the end of the second week. These results suggest that the ISO-evoked increase in cardiac polyamines was mediated, at least in part, by the renin angiotensin system, which was stimulated by ISO.

Animals↗
PubMed1992

[Aspergillosis involving the thoracic spinal cord--an autopsy case].

A 63 year old male complained of persistent backache and productive cough. The chest X-ray revealed the fungus ball at the left apical-posterior segment and Aspergillus fumigatus was cultured from the sputum. He was treated on fulconazole and miconazole. Six months later, motor and sensory paralysis below the mamillary level and urinary and stool incontinence developed. A magnetic resonance image disclosed the destruction of the second thoracic spinal vertebra involved by the cavitated fungus ball of the left lung. Continuous peroral administration of antifungal drugs was not successful, and he expired with severe dyspnea. The autopsy revealed an extensive granulomatous and purulent change of the epidural and subdural spaces of the second to fifth thoracic spinal cord. Subdural inflammation extended to the lower thoracic and lower cervical level. Thoracic spinal cord revealed an extensive myelomalacia predominantly involving the left lateral white column, and also anterior and posterior columns. Small areas of the white matter were cystic. The left anterior horn cells revealed severe central chromatolysis. Moderate lymphocytic and plasma cell infiltration was found around the vessels within the cord. A few thrombi were found in the vein near the anterior nerve root. Central nervous system involvement of pulmonary aspergillosis is quite uncommon. However, there are a few reports of patients with paraplegia secondary to the spinal extension by aspergillus infection. Sheth et al. described that epidural and subdural granulomatous change with aspergillus abscesses and spinal cord myelomalacia is comparable to metastatic carcinoma. However, the aspergillus infection in the spinal cord is more extensive and destructive.(ABSTRACT TRUNCATED AT 250 WORDS)

Aspergillosis↗
PubMed1992

[An autopsy case of primary central nervous system lymphoma with diffuse intracerebral lesion].

A case of primary central nervous system lymphoma (PCNSL) who initially showed clinical pictures like encephalitis and diffuse lesions on MRI was reported, including postmortem pathologic examinations. A 68-year-old woman was seen in March, 1990 with a 1-month history of the progressive gait disturbance. She was very unstable and could barely stand by herself, though she did not show any focal neurologic deficits. She showed no evidence of systemic diseases. The cerebrospinal fluid analysis was normal. T2-weighted image of MRI demonstrated the diffuse symmetric hyperintense lesions mainly in the periventricular white matter. The progressive intellectual decline and the spasticity of four limbs developed as the diffuse lesions on MRI gradually extended. Despite the administration of corticosteroids under the presumptive diagnosis of PCNSL, she rapidly fell into the apallic syndrome within two months. Her EEG showed periodic synchronous discharges. Three months later, she suddenly developed signs of right uncal herniation. CT showed a large mass lesion in the right hemisphere. After the anti-edema therapy, signs of herniation regressed. The serial CT scans demonstrated a gradual decrease in the mass effect, while another multi-nodular lesions appeared and then disappeared one after another bilaterally. Eventually, the diffuse low densities in the cerebral white matter and the ventricular enlargement had remained. She died of bronchopneumonia eight month after the onset of symptoms. The clinical importance of the diagnosis of PCNSL which initially shows diffuse symmetric lesions without a mass is stressed. Postmortem examinations revealed PCNSL, diffuse, large cell type according to the Lymphoma Study Group classification. The lymphoma cells were proved to be B cell origin from the immunohistochemical study of frozen tissue.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1991

Frank melena in a patient with fallopian tube pregnancy.

We present herein a case of a young woman who experienced lower intestinal hemorrhage caused by ischemic necrosis of the small intestine induced by the compression of a Fallopian tube hematoma in an ectopic pregnancy. All accessible preoperative attempts to clear the site of the bleeding were unsuccessful and an exploratory laparotomy was indicated seventeen days after the development of melena. An ileocecal resection and right salpingectomy finally had to be performed.

Adult↗
PubMed1991

Solid adenosquamous carcinoma of the liver. A case report and review of the literature.

This is a report of a fatal case of a primary and solid adenosquamous carcinoma (ASC) of the liver in a 58-year-old Japanese woman. There was no association with biliary cysts. Histochemistry and immunohistochemistry support the contention that the neoplasm arose from squamous metaplasia of a mucus-secreting adenocarcinoma (MSA) of intrahepatic biliary duct epithelium.

Adenocarcinoma↗
PubMed1989

Primary amyloid tumors of the jejunum producing intestinal obstruction.

The proximal jejunum, containing four separate amyloid tumors, was resected from a chronically constipated 71-year-old male exhibiting IgG lambda monoclonal gammopathy. Amyloid was deposited in the jejunal wall, mesentery and regional lymph nodes, but was not seen in gastric and rectal biopsy samples. Two years after surgery, the patient is well, but the monoclonal gammopathy persists.

Aged↗