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Biomedical subjects

K Hamada

Publications and source records attributed to K Hamada.

At least 469 records · Page 26Linked to original sources
PubMed1984

Induction of lymphosarcoma in sheep inoculated with bovine leukaemia virus.

Five sheep were experimentally inoculated with BLV in order to study the humoral immune response in animals infected with bovine leukaemia virus (BLV). During experimental periods of 46 months, 2 sheep died with leukaemia and one sheep showed splenomegaly and proliferation of tumour cells. The other 2 sheep were clinically normal. All of the inoculated sheep developed antiviral antibodies 1 month after inoculation and BLV could be re-isolated in lymphocytes 2 to 3 months after inoculation. Antibody against glycoprotein antigen (gp51) of BLV appeared earlier than the antibody against protein antigen (p24) and antibody titres of the former were higher than those of the latter during the course of the experiment. The complement dependent antibody cytotoxicity test was performed for the detection of antibody against BLV-related cell membrane antigen with 2 different kinds of target cells; FLK cells which are foetal lamb kidney cells chronically infected with BLV and SF-28 cells which are sheep fibroblasts transformed with BLV in vitro. All 5 sheep developed cytotoxic antibodies against both types of cells. In sera from two leukaemic sheep, cytotoxic antibody titres against SF-28 cells gradually decreased 30 months after inoculation and finally became negative one to 3 months before they died of leukaemia. However, these leukaemic sheep persistently produced antibodies against gp51 and p24.

Animals↗
PubMed1984

Purification and properties of gene 18 product of bacteriophage T3.

Two noncapsid proteins of T3 and T7 phage, the products of gene 18(gp18) and gp19, are required for DNA packaging. By using in vitro complementation for DNA packaging as an assay system, T3 gp18 was purified to near homogeneity from an extract prepared cells infected with a mutant of gene 19(19- extract). The purified gp18 consisted of a single polypeptide having a molecular weight of 10,000, and was eluted as dimers and higher multimers from Sephadex G-75 columns. T7 gp18 was purified by the same procedures as that for T3 gp18 and behaved in the same manner as T3 gp18 throughout all purification steps. Gp18 from either T3 or T7 phage complemented both T3 and T7 18- extract for DNA packaging. These results indicate that, in contrast to gp19 [H. Fujisawa and M. Yamagishi (1981) Prog. Clin. Biol. Res. 64, 239-252], gp18 does not have specificity for T3 or T7 DNA during the in vitro packaging reaction. T3 gp18 was purified from extract containing functional gp19. The gp18 copurified with the gp19 activity. Gp18 and gp19 activities were stable when they were copurified but were unstable when purified separately. These results suggest that gp18 and gp19 function as a complex in the DNA packaging process. The gp18-gp19 preparation had a prohead-stimulated, DNA-dependent ATPase activity.

Adenosine Triphosphatases↗
PubMed1984

Induction of mutations and chromosome aberrations in lung cells following in vivo exposure of rats to nitrogen oxides.

In order to investigate the mutagenic effects of nitrogen oxides ( NOx ), induced mutations and chromosome aberrations were examined using primary lung cells obtained from rats exposed in vivo to NO2 and NO. Rats were exposed to nitrogen oxide gases at concentrations of 8-27 ppm for 3 h in a stainless steel chamber. Over the range 15-27 ppm, NO2 significantly increased mutation to ouabain resistance. Over a similar dose range, NO significantly increased mutation only at the highest concentration (27 ppm). Following NO2 exposure, chromosome aberrations (mainly chromatid type) were induced in chromatid breaks, 2.5-11.6-fold over the control at 8 and 27 ppm, respectively.

Animals↗
PubMed1984

[Bilateral primary germ cell tumors of the testis: report of two cases and review of the literature].

Bilateral germ cell tumors of the testis are not common. The contralateral tumor may develop simultaneously or sequentially. In both cases, bilateral involvement is postulated to represent two primary tumors. Case 1: A 47-year-old male was seen with a painless nodular mass in the right testis. Physical examination revealed hard swelling of both testes besides a nodule in the right testis. He underwent bilateral radical orchiectomy; and, microscopical both tumors proved to be seminoma. Although bipedal lymphangiography was negative for nodal metastases, postoperative irradiation to the pelvic and para-aortic lymph nodes was given to a total dose of 5,800 rad. The patient was alive 15 years after treatment for bilateral testicular tumors. Case 2: A 53-year-old male presented with painless left scrotal swelling. Physical examination showed not only an enlarged hard testis in the left scrotum but also a palpable hard mass in the right testis. Bilateral radical orchiectomy was performed and pathological examination revealed pure seminoma in both testes; a 1 cm mass in the right testis and almost completely replaced tumor in the left testis. Evaluation including retroperitoneal lymph node dissection revealed no metastatic disease. Postoperatively, the patient received 1,900 rad of irradiation to the retroperitoneal space. He is well one year after surgery and has no evidence of recurrence or metastasis. Previous reports of bilateral germ cell testicular tumors are reviewed and the incidence, age, predisposing factors, interval between the first and second tumors, histology, pathogenesis, prognosis, and management are discussed.

Age Factors↗
PubMed1984

[IgA nephropathy and Henoch-Schönlein purpura nephritis: clinicopathological, histopathological immunohistological, and electronmicroscopical characteristics].

A comparative analysis on clinicopathological, histopathological, immunological and electronmicroscopical characteristics was performed between 57 cases of IgA nephropathy and 20 cases of Henoch-Schönlein purpura nephritis (HSPN). In IgA nephropathy, most cases were discovered incidentally by asymptomatic proteinuria or hematuria, while H-S nephritides were associated with systemic symptoms such as abdominal and joint pain, in addition to purpura. The average age of HSPN was younger than that of IgA nephropathy. Histologically, mesangial cell proliferation with mild enlargement of matrix, focal thickening of glomerular, capillary loop and Bowman's capsule adhesion were much frequent in HSPN, while enlargement of mesangial matrix without mesangial cell proliferation was characteristic to IgA nephropathy and thickening of glomerular capillary loops was less frequent. However, there were no clear differences between HSPN and IgA nephropathy in advanced stage. Immunofluorescent microscopy demonstrated no qualitative dissimilarities in regard to deposition in immunoglobulins, C3, and fibrinogen, except more frequent deposition of these serum component in glomerular capillary loops of HSPN. Electron microscopic observation revealed mesangial massive electron dense deposit (EDD) in IgA nephropathy, while mesangial EDD were small and granular in HSPN. Hemispherical body, which is massive hemispherical EDD protruding to intercapillary space from mesangium, was found in significantly higher percentage in IgA nephropathy. Distribution of EDD in glomerular capillary was focal in either of HSPN and IgA nephropathy. Intramembranous and subepithelial EDD were frequent and extensive in HSPN compared with IgA nephropathy in which capillary EDD was mainly observed in subepithelial portion. Detailed morphological investigations were able to disclose several differences between HSPN and IgA nephropathy. However, these differences were rather quantitative. A common or similar pathogenesis is suggested for HSPN and IgA nephropathy.

Adolescent↗
PubMed1983

A novel guanine-guanine base pairing: crystal structure of a complex between 7-methylguanosine and its iodide.

7-Methylguanosine, one of the biologically important minor nucleosides, could be crystallized as a complex of its zwitterionic form and its iodide, and the crystal structure was determined by the X-ray diffraction method. The crystals belong to the triclinic space group P1 with the unit cell dimensions: a = 7.678(1), b = 18.094(3), and c = 5.711(1) A, alpha = 79.32(1), beta = 80.14(1) and gamma = 76.90(1) degrees. The structure was solved by the heavy atom method and refined by the least-squares method to give a final R index of 0.075. The novel reverse Watson-Crick type base pairing observed between a positively charged molecule and a deprotonated one indicates that the deprotonation at the N(1) position promoted by the alkylation at the N(7) position may interrupt the formation of the normal Watson-Crick type GC base pair. The conformations about the glycosidic bond and the sugar puckering are quite different between the two molecules: the former has anti and C(4')-exo,C(3')-endo and the latter syn and C(1')-exo-C(2')-endo.

Base Composition↗
PubMed1983

Mutagenicity in Salmonella typhimurium TA98 of the serum extract of the organic matter derived from airborne particulates.

To investigate the interactions between mutagens and serum components, the mutagenicity of the serum extract of the organic matter derived from airborne particulates (tar) was examined by the Salmonella/mammalian microsome mutagenicity test. The mutagens in the organic matter were found to be extracted with serum but not with saline. The mutagenic activity of the serum extract of the tar, however, decreased to about 60% compared with that of the DMSO extract, when they were activated by S9 mix. On the other hand, without S9 mix, the mutagenic activities of the serum and DMSO extracts were about the same. Gel filtration of the serum extract was carried out and followed by mutagenicity testing of each fraction. It is suggested that the mutagens, which require metabolic activation, combine mainly with beta-lipoproteins and the direct mutagens with both alpha- and beta-lipoproteins in serum.

Air Pollutants↗
PubMed1983

Chronic sensory and autonomic neuropathy.

A man with sensory neuropathy had evidence of autonomic failure: abnormal pupils, hypohidrosis, esophageal dilation, diarrhea, hypotension, orthostatic hypotension, sphincter disturbance, and impotence. Functional tests revealed abnormalities of both sympathetic and parasympathetic systems, mainly postganglionic. Autopsy revealed degeneration of posterior columns, posterior nerve roots, posterior root ganglia, and peripheral nerves. Degeneration was also observed in the sympathetic trunk, vagal nerve, and myenteric plexus. Neurons in the intermediolateral columns were preserved. Progressive sensory neuropathy with dysautonomia seems to be a new disease.

Autonomic Nervous System Diseases↗
PubMed1983

Qualitative and quantitative changes in plasma luteinizing hormone (LH) under stimulation by intravenous infusion of synthetic luteinizing hormone-releasing hormone (LHRH) in Japanese monkeys (Macaca fuscata) as assessed by electrofocusing.

Using 5 adult Japanese monkeys (Macaca fuscata) of both sexes, the qualitative and quantitative changes in plasma LH caused by LHRH administration were examined before and after castration. Five hundred micrograms synthetic LHRH was infused for 2 hrs and blood samples were obtained every 15 min for 5 hrs under ketamine hydrochloride anesthesia. Plasma LH levels were determined by an in vitro bioassay using the mouse testis interstitial cell preparation. The LHRH infusion induced a biphasic release of LH in intact animals of both sexes and in castrated females but not in castrated males. The biphasic pattern of LH release was characterized by an initial acute rise followed by a plateau or a fall and the consecutive second rise after a long latent period. Aliquots of plasma samples obtained during 30-90 (corresponding to the initial rise) and 120-210 min (corresponding to the second rise) after the initiation of LHRH infusion were pooled separately (plasma pools I and II, respectively) and subjected to isoelectrofocusing (IEF) fractionation. The IEF fractionation was performed in ampholine-sucrose gradient, pH range 3.5-10, under a constant electrical power supply (3 W, 700 V) for 48 hrs at 4 degrees C. After the completion of the IEF fractionation the LH activity in each fraction was measured by the in vitro bioassay. The IEF fractionation separated plasma LH into 6 distinct species in terms of pI values. When the IEF profiles of plasma pools I and II in intact animals of both sexes were compared, the increase and the decrease in acidic to neutral LH and alkaline LH, respectively, were consistent and significant in plasma pool II. Changes of the same kind were further exaggerated when the IEF profiles in castrated animals were compared with those in non-castrated ones. The acidic LH may represent the LH species newly synthesized and not well processed. The LH species possessing pI values of 7.5-8.5 is likely to be the mature type of LH exhibiting high biological potency. The LH species migrating in the high alkaline region seems to be the LH of over-maturation.

Animals↗