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Biomedical subjects

H Maeda

Publications and source records attributed to H Maeda.

At least 1,261 records · Page 70Linked to original sources
PubMed1982

Circular dichroism and biochemical properties of the hepatitis B virus core antigen.

The hepatitis B virus (HBV) core antigen was purified by mild procedures, including hydroxyapatite column chromatography, with care taken to avoid the degradation of the particles. Circular dichroism (CD) of the HBV core particles in saline showed low intensities of negative ellipticities in the region dominated by amide bond absorption. Acid treatment of the particles induced a remarkable change in the CD spectrum, with the appearance of a positive extremum at about 208 nm. The amino acid composition and the COOH-terminal residue of the isolated core polypeptide (Mr 21,000-21,500) were shown to be essentially the same as those of the polypeptide deduced from the nucleotide sequences which had been proposed for the HBV core antigen by other laboratories. We failed to detect any NH2-terminal dansyl-derivatives from the core polypeptide by the dansyl-Edman method. We also showed by the method of fluorescein polarization that the core polypeptide conjugated with fluorescein isothiocyanate has an affinity for serum albumin. This may indicate a state of disassembled or non-assembled core polypeptide in sera.

Amino Acids↗
PubMed1982

Reserpine and sympathetic denervation cause an increase of postsynaptic alpha 2-adrenoceptors.

The changes in alpha-adrenoceptors in rat vasa deferentia after injections of reserpine and 6-hydroxydopamine (6-OHDA) were examined in binding studies with [3H]WB4101 and [3H]clonidine. On intraperitoneal injection of reserpine (0.5 mg/kg body weight per day, 2 days), [3H]clonidine binding sites increased by about 2.0 pmol/g wet weight; the binding sites were not detectable in vasa from control rats. [3H]WB4101 binding sites showed no apparent change in amount. After a single injection of 6-OHDA (30 mg/kg body weight), [3H]clonidine binding sites amounted to about 1.1 pmol/g wet weight. The data suggest that both reserpine treatment and incomplete chemical denervation with 6-OHDA cause an increase of [3H]clonidine binding sites in the postsynaptic region of rat vasa deferentia. The possibility was tested by completely denervating rat vasa deferentia by chemical treatment and operation. The treatments increased the binding sites to about 0.9 and 1.0 pmol/g wet weight, respectively over the control level. The results imply that the binding sites indeed also increased in the postsynaptic area.

Animals↗
PubMed1982

Reversible and irreversible conversion between the intermolecular beta-structure and the disordered state of poly(S-carboxymethyl-L-cysteine) in aqueous media.

Conversion between the intermolecular beta-structure and the disordered state of a fractionated low molecular weight sample of poly(S-carboxymethyl-L-cysteine) was examined mainly by the measurements of circular dichroism in the absence of salt as well as in the presence of 20 mM NaClO4 or NaCl. In 20 mM NaClO4 or NaCl solutions, the conversion was reversible. Under this condition, it was confirmed by direct and unambiguous evidence provided from the viscosity and the reduced scattering intensity that the beta-structure was formed by intermolecular association. At low degrees of neutralization, the pH increased on dilution while it remained constant over a wide range of concentration at a high degree of neutralization. In the absence of salt, the conversion was often irreversible with respect to a concentration change at a constant degree of neutralization or to a change in the degree of neutralization at a constant concentration. The extent of the irreversible conversion decreased with the amount of beta-structure in the solution. The dissociation of aggregates was very slow at low ionic strengths. It was inferred that the irreversible nature of the conversion arose from this slow dissociation of aggregates.

Circular Dichroism↗
PubMed1982

Effects of peripheral stimulation on the activity of neurons in the ventral tegmental area, substantia nigra and midbrain reticular formation of rats.

Extracellular recordings were obtained from neurons in the ventral tegmental area (VTA), the substantia nigra, including the zona compacta (SNC) and the zona reticulata (SNR), and the midbrain reticular formation (FOR) of adult female albino rats anesthetized with urethane and chloral hydrate. Based on electrophysiological characteristics the neurons were divided into two types. Type I neurons, with relatively long spike durations and slow discharge rates, were confined to the VTA and SNC. Type II neurons, with shorter spike durations and faster discharge rates, were observed in the SNR and FOR as well as the VTA and SNC. The effects of foot pinch (FP), tail pinch (TP) and stimulation of the vaginal cervix (VC) on the activity of the two types of neurons were investigated. Previously it was demonstrated that FP was aversive, TP elicited locomotion, sniffing and gnawing responses and VC lordosis response, vocalization and immobility. For approximately two-thirds of the neurons the effects of the three peripheral stimuli were similar; either they were activated or suppressed. Approximately 8 percent of the neurons were suppressed by FP and TP and activated by VC whereas a similar number were activated by FP and TP and suppressed by VC. Type 1 and Type II neurons in the VTA and SN were activated and suppressed by the peripheral stimuli with suppression being the most common response to FP and TP. The results are consistent with the view that VTA and SN neurons integrate a number of central and peripheral inputs.

Action Potentials↗
PubMed1982

Proteolytic digestion of human serum apolipoproteins by porcine pancreatic elastase.

We studied the proteolytic action in vitro of free and alpha 2-macroglobulin-bound porcine pancreatic elastase [EC 3.4.21.11] on the apolipoproteins of plasma: very low density lipoprotein (VLDL), low density lipoprotein (LDL), and high density lipoprotein (HDL). Polyacrylamide gel electrophoresis, isoelectric focusing and immunodiffusion tests of elastase-treated plasma lipoproteins revealed that apolipoprotein C-II and C-III polypeptides were more susceptible to elastase in free form than plasma apolipoproteins (A-I, A-II, B, and E). Elastase bound to alpha 2-macroglobulin did not show any such activities.

Animals↗
PubMed1982

A new assay method for DNase by fluorescence polarization and fluorescence intensity using DNA-ethidium bromide complex as a sensitive substrate.

The fluorescence polarization method was applied for the determination of DNase-activity using ethidium bromide-labeled DNA as a substrate. This assay was based on a decrease in fluorescence intensity or fluorescence polarization value, which reflected degraded molecular size resulting from the specific cleavage of DNA by the enzyme. DNase activity was quantitatively determined above 0.1 ng/ml of the enzyme. A decrease in fluorescence intensity or polarization value brought about by DNase was inhibited by the specific inhibitors of DNase such as EDTA, pyrophosphate, and thymidine-3',5'-diphosphate. In addition, specificity of the change of polarization value was established using other enzymes. Since this method was simple, rapid and sensitive, it is applicable for both quantitative and qualitative assays as well as for the kinetic analysis of the enzyme.

DNA↗
PubMed1982

Bone scintigraphy in pulmonary alveolar microlithiasis: a comparative study of radioactivity and density distribution.

A histologically proven case of pulmonary alveolar microlithiasis that demonstrated intense lung uptake of Tc-99m-MDP on a bone scan is presented. The spatial distribution within the lungs of the radioactivity and density was assessed either by single photon emission computed tomography (SPECT), or x-ray computed tomography (CT) respectively, and the regional magnitude of the two parameters were compared. The quantitative study of regional radioactivity and density revealed that both the parameters distributed symmetrically, showing gradual increase in magnitude from the upper to the lower lung regions. The radioactivity-density association observed in our patient may indicate on-going formation of microcalculi throughout the lungs, the degree of which is greater at the sites of more severe involvement.

Bone and Bones↗
PubMed1982

Epidermal origin of the amyloid in localized cutaneous amyloidosis.

A case of localized cutaneous amyloidosis which developed after a lichen planus-like skin reaction is reported. The amyloid consisted of amyloid fibrils enveloped by heparan sulphate granules. These amyloid fibrils reacted to anti-human keratin antibody, indicating an epidermal origin for the fibrils.

Aged↗
PubMed1982

A new B-cell alloantigen, TB21, coded for in the HLA-D/DR region.

A new B-cell alloantigen, designated as TB21, was serologically defined by 2 monospecific sera, T383 and T2200. Both T383 and T2200 had cytotoxic titers of 1:8 against TB21 positive B cells and were highly correlated to each other (r = 0.876). The phenotype frequency of TB21 was approximately 55% in the Japanese population. TB21 was strongly associated with DRw9 and weakly with DR5, but was definitely distinct from the known supertypic specificities such as MT or MB antigens. Family studies showed that TB21 segregated with different DR antigens on different haplotypes, indicating that TB21 is coded for by a gene at a closely linked but distinct locus from HLA-DR. Furthermore, TB21 was preferentially detected on B cells but not on monocytes by complement-dependent cytotoxicity. Failure of detection of TB21 on monocytes further distinguished the TB21 antigen from DR and MT antigens. Results of this study suggest that there exist 2 kinds of B-cell alloantigens coded in the HLA region: DR and MT antigens, and other B-cell alloantigens represented by TB21.

Absorption↗
PubMed1982

In vitro mode of action, pharmacokinetics, and organ specificity of poly (maleic acid-styrene)-conjugated neocarzinostatin, SMANCS.

The organ specificity and pharmacokinetics of SMANCS, poly (maleic acid-styrene)-conjugated neocarzinostatin (NCS), were investigated in rats. The drug activity accumulated primarily in the regional lymph nodes after subcutaneous injection. After intravenous injection, the drug was found in the kidney, lymph nodes, and bladder in very high concentrations, and in lesser concentrations in the bone marrow, lung, small intestine, liver and spleen. The urinary excretion rate and total recovery of the drug after intravenous injection were higher than those after subcutaneous injection. SMANCS, having a molecular weight of 2.5 x 10(4) daltons, was degraded in vivo to NCS (mol. wt. about 1.1 x 10(4)). This was also confirmed in vitro by incubating the drug with cell homogenates. SMANCS caused strand scission of DNA similarly to NCS in lymphoblastoid cells. However, in a cell-free system using colicin E1 plasmid DNA, a high concentration of SMANCS was required to produce DNA degradation detectable by the alkaline sucrose gradient method.

Animals↗
PubMed1982

[Pharmacokinetic one-compartment model using neocarzinostain as a prototype drug and its clinical application to chemotherapy for brain tumor. Part II. A clinical trial with selected protocol].

Neocarzinostatin as previously reported, appeared to exhibit an intense cytotoxicity to the glioblastoma cells and some other malignant brain tumor cells, such as pineal germinoma or medulloblastoma, which are notoriously known to disseminate into the cerebrospinal fluid space. In vitro study, the minimum susceptibility of glioblastoma cells to neocarzinostatin was found to be below 0.005 microgram/ml, whereas normal glia cells were not affected at 0.3 microgram/ml. This study indicated that neocarzinostatin was extremely effective in the treatment of malignant brain tumor without affecting normal neural tissue. Pharmacokinetic study was performed in order to establish intermittent intrathecal perfusion therapy and to prevent subarachnoid dissemination of the brain tumor cells. Experimental results were applied to the treatment of 12 patients with brain tumor, who had shown positive cytology of the cerebrospinal fluid. Follow-up investigation showed quite a favorable result and it was considered that prophylactic irradiation to the entire spinal column could be replaced with intrathecal administration of neocarzinostatin. During clinical application no noticeable side effect was encountered and active stimulation of macrophages, which were mobilized into the CSF space, was another unexpected advantage of this treatment.

Adolescent↗