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Biomedical subjects

T Azuma

Publications and source records attributed to T Azuma.

At least 289 records · Page 16Linked to original sources
PubMed1989

[The effect of chemical sympathectomy on the cell kinetics of gastric mucosa in golden hamsters].

The effects of chemical sympathectomy on the differentiation of the generative cells, superficial epithelial cells and gastrin cells of the gastric mucosa of hamster were examined by 3H-thymidine autoradiography. The labeling indices of the generative cell zone in the gastric mucosa and antral gastrin cells showed a transient significant decrease after chemical sympathectomy, and then they were gradually restore with time. After 4 weeks onward, the labeling indices of the generative cells showed a slightly low value compared with those in controls. The renewal of superficial epithelial cells and gastrin cells was examined in the hamster sympathectomized for 4 weeks. The time required for the differentiation to PAS positive superficial epithelial cells or gastrin cells had a tendency to elogate after chemical sympathectomy. These results suggest that chemical sympathectomy played an inhibitive action on the proliferation and the differentiation of gastric mucosa.

Animals↗
PubMed1989

Application of new silicone gel to sustained release dosage form of antitumor drug.

The object of this study was to develop a sustained release implantable dosage form of a new silicone gel (PHYCON 6600R) which undergoes addition polymerization to produce a solid gel at ordinary temperature. Implantable PHYCON-drug composites were studied as a means of tumor therapy using 3',5'-diesters of 5-fluoro-2'-deoxyuridine (FUdR-Cn) as a model for antitumor drugs. Using an in vitro dissolution test, we found that the release characteristics of drugs from these preparations could be controlled by the addition of powdered L-alanine. In vivo studies of antitumor activity were carried out, using preparations containing the dodecyl ester (FUdR-C12) by measuring the lifespan of lymphoma-inoculated mice. Antitumor activity, reflected in increased lifespan, was shown to be greater following intraperitoneal administration of the PHYCON formulations (drug and L-alanine) than following injections of the drug alone. Our results suggest that sustained release implantable formulations of antitumor drugs in PHYCON might be suitable for tumor chemotherapy.

Animals↗
PubMed1989

Application of PHYCON 6600 to achieve sustained release of an antitumor drug (carmofur).

This study attempted to develop sustained release implantable dosage forms based on PHYCON 6600, a new silicone gel. The solid gel is prepared at ambient temperature by polymerization of two basic components (PHYCON A and PHYCON B solutions) for about 1 h. The application we explored was the use of implantable PHYCON-drug composites in tumor therapy. Carmofur (1-hexylcarbamoyl-5-fluorouracil, HCFU) was chosen as a practical antitumor drug. Using an in vitro dissolution test, near zero-order release rate was observed over a period of about 35 days. The amount of drug released by the 'burst phenomenon' was found to be less than the HCFU toxic dose. In vivo studies of antitumor activity were carried out by measuring the lifespan of lymphoma-inoculated mice (ILS). The increase in lifespan (38.5%) following intraperitoneal administration of the PHYCON formulations was similar to that (36.4%) following injection of the drug alone for 5 days. Our results suggest that the injectable and implantable sustained release formulations of the antitumor drug in PHYCON might be suitable for tumor chemotherapy.

Animals↗
PubMed1989

Effect of daily energy expenditure on the creatinine clearance and daily urinary protein excretion of patients with mesangial proliferative glomerulonephritis.

In the present study, the relationships among daily energy expenditure, renal function (creatinine clearance, Ccr), and daily urinary protein excretion were examined. In total, 104 adult patients (from 9 renal clinics in Japan) with primary chronic glomerulonephritis were fitted with a portable calorie counter for about two weeks to estimate their daily energy expenditure. On two separate days when the energy expenditure was expected to be contrastingly different, urine collection and blood sampling were performed, and the Ccr and daily urinary protein excretion were determined. Multiple regression analysis of Ccr clearly demonstrated a significant correlation between its acceleration and increase in the daily protein intake or protein excretion. In mesangial proliferative glomerulonephritis showing a constant level of protein intake, the enhancement of Ccr revealed a significant inverse relation to the increase in daily energy expenditure (%BMR). It was demonstrated statistically that a daily energy expenditure exceeding 150 %BMR slowed the Ccr down. This limit was almost the same as the level in healthy adults living in urban cities of Japan. The urinary protein excretion was significantly correlated with the daily protein intake. These results should be taken into consideration in prescribing for each individual patient an allowable degree of labor or any other activity and an adequate dietary regimen, and also in evaluating the efficacy of a drug for glomerulonephritis.

Adolescent↗
PubMed1989

[Ontogeny of pancreatic gastrin cells in neonatal rat].

It is well known that gastrin immunoreactive cells are observed in the fetal and postnatal rat pancreas. The role of the gastrin cells is unknown, however, it has been suspected that pancreatic gastrin may influence the development of pancreas and the gastrointestinal tract. The present study shows the localization of pancreatic gastrin cells and the ability of auto-proliferation of them in development. Gastrin cells were seen in 0-d to 2-wk-old rats in islet and in 0-d to 4-wk-old rats among exocrine cells. The ratio of gastrin cells to islet cells decreased in neonatal development and in rats older than 14-d gastrin cells were never observed in islet. Labeling indices of pancreatic gastrin cells after one injection of tritiated thymidine were 2.6% to 4.6% for 10 days after birth. It was suggested that gastrin cells have the ability of autoproliferation for 10 days after birth.

Age Factors↗
PubMed1988

Characterization of the combining site of mouse myeloma protein M315.

The interaction of M315 with 2,4-dinitrophenyl haptens was studied. 2,4-Dinitroaniline (DNP-NH2) showed maximum affinity to M315 at about pH 4. The pH dependence of the association constant of DNP-NH2 to M315 showed three transitions at pH 4.7, at pH 7.2, and below pH 9, respectively. Since the DNP-NH2 molecule has no charged group in this pH range, the transitions were explained in terms of amino acid residues with ionizable side chains in M315. Judging from the pK values and the effect of succinylation, these transitions were concluded to be related to ionizations of carboxyl, imidazole, and phenol groups, respectively. Measurement of the fluorescence of affinity-labeled M315 suggested that the transition at pH 4.7 reflected an equilibrium between two forms of M315 with different conformations of the combining site. The contribution of the amino acid sequence on the light (L) chain to the interaction with haptens was studied by use of antibodies (Abs) reconstituted from the heavy chain of M315 (H315) and either a homologous or a heterologous L chain. The reconstituted heterologous Ab (H315L952) showed similar pH dependence of binding to DNP-NH2 to that of the homologous Ab (H315L315). Moreover, the two Abs showed no appreciable difference in binding to DNP-haptens of different sizes. These results suggested that the difference in the amino acid sequences of L315 and L952, which originated by a somatic hypermutation, has little effect on the ligand binding.(ABSTRACT TRUNCATED AT 250 WORDS)

Affinity Labels↗
PubMed1988

Property of class I H-2 alloantigen-reactive Lyt-2+ helper T cell subset. Abrogation of its proliferative and IL-2-producing capacities by intravenous injection of class I H-2-disparate allogeneic cells.

The present study investigates the distinctiveness of Class I H-2 alloantigen-reactive Lyt-2+ helper/proliferative T cell subset in the aspect of tolerance induction. Primary mixed lymphocyte reactions (MLR) revealed that Lyt-2+ and L3T4+ T cell subsets from C57BL/6 (B6) mice were exclusively capable of responding to class I H-2 [B6-C-H-2bm1 (bm1)]- and class II H-2 [B6-C-H-2bm12 (bm12)]-alloantigens, respectively. Anti-bm12 MLR was not affected by i.v. injection of bm12 spleen cells into recipient B6 mice. In contrast, a single i.v. administration of bm1 spleen cells into B6 mice resulted in the abrogation of the capacity of recipient B6 spleen and lymph node cells to give anti-bm1 MLR. This suppression was bm1 alloantigen-specific, since lymphoid cells from B6 mice i.v. presensitized with bm1 cells exhibited comparable anti-bm12 primary MLR to that obtained by normal B6 lymphoid cells. Such tolerance was rapidly (24 h after the i.v. injection of bm1 cells) inducible and lasting for at shortest 3 wk. Addition of lymphoid cells from anti-bm1-tolerant B6 mice to cultures of normal B6 lymphoid cells did not suppress the proliferative responses of the latter cells, indicating that the tolerance is not due to the induction of suppressor cells but attributed to the elimination or functional impairment of anti-bm1 proliferative clones. The tolerance was also demonstrated by the failure of tolerant lymphoid cells to produce IL-2. It was, however, found that anti-bm1 CTL responses were generated by tolerant lymphoid cells which were unable to induce the anti-bm1 MLR nor to produce detectable level of IL-2. These results demonstrate that class I H-2 alloantigen-reactive Lyt-2+ Th cell subset exhibits a distinct property which is expressed by neither Lyt-2+ CTL directed to class I H-2 nor L3T4+ Th cells to class II H-2 alloantigens.

Animals↗
PubMed1988

Alterations in gastric mucosal microvascular endothelium in a stressed condition--relevance to gastric ulcerogenesis.

The present paper describes the morphological and functional alterations of the gastric mucosal microvascular endothelium under restraint-stressed condition. On the basis of the direct cholinergic innervation of capillaries and non-muscular venules in the gastric mucosa, these endothelial changes would be caused by the stress-induced overstimulation of the cholinergic nerves and modified by the degranulation of mast cells, contributing to the stress-induced ulcer formation as schematically illustrated in Fig. 10.

Aged↗
PubMed1988

The aortic alpha 1-adrenergic receptor in familial amyloidotic polyneuropathy.

To assess the pathophysiology of the sympathetic nervous system in familial amyloidotic polyneuropathy (FAP), we used 3H-bunazosin to identify and characterize the alpha 1-adrenergic receptor in human aortic membranes. The binding of 3H-bunazosin was rapid, readily reversible, stereospecific, and saturable. The Scatchard analysis described a single class of binding sites with a dissociation constant (KD) of 0.370 +/- 0.035 nM and a maximal binding capacity (Bmax) of 11.8 +/- 1.30 fmol/mg protein in control patients. Competition analysis demonstrated the alpha 1-adrenergic specificity of the 3H-bunazosin binding sites in human aortic membranes. The KD and Bmax of 3H-bunazosin binding in four FAP patients was 0.274 +/- 0.052 nM and 7.79 +/- 0.15 fmol/mg protein, respectively; these values did not differ significantly from those in 14 control patients. An increase in Bmax or affinity of alpha 1-adrenergic receptors may not be the cause for denervation supersensitivity in FAP.

Adrenergic alpha-Antagonists↗
PubMed1988

Involvement of autonomic nervous system in gastric mucosal defense mechanism.

This article describes the histochemical, immunohistochemical, radioautographic, and ultrastructural localizations of aminergic and peptidergic nerves, neurotransmitter receptors, and their binding sites in the stomach wall. Cholinergic and vasoactive intestinal polypeptide (VIP)-ergic nerve fibers are distributed along the gastric microvasculature, within the myenteric and submucosal plexuses, and in the muscularis mucosae and circular muscle layer. In the mucosa, both nerve fibers evenly extend along the capillaries in association with the epithelial cells up to the mucosal surface. In particular, cholinergic nerves are proved to doubly innervate the mucosal capillaries and nonmuscular venules as well as the parietal cells. Adrenergic and neuropeptide Y (NPY)-containing nerves are distributed primarily along the arterioles of the gastric microvasculature, within the myenteric plexuses, and in the circular muscle layer. These nerve fibers extend up to the basal portion of the mucosa in close association with small arterioles, capillaries, and epithelial cells. Some of the adrenergic nerve axons are coexistent with the cholinergic nerve axons within the Schwann cell. Histamine H1 receptors are widely located on the walls of arterioles, capillaries and venules, while H2 receptors are evident not only on the parietal cells but also on the walls of the collecting venules and surrounding capillaries in the mucosa. Dopamine D1 receptors are predominantly located on the smooth muscle cells of the arterioles near the muscularis mucosae, while D2 receptors are present on the walls of postcapillary venules and collecting venules. Functional coordination of both intramural peptidergic nerves as intrinsic origin and aminergic nerves as extrinsic origin is considered to be essential for maintaining the gastric mucosal defense mechanism against a variety of aggressive factors.

Animals↗
PubMed1988

Monoclonal antibodies to O4 antigen of Vibrio parahaemolyticus.

Four monoclonal antibodies were prepared against O4 antigen of Vibrio parahaemolyticus. All the antibodies were shown to be specific for O4 antigen by agglutination with heat-killed O-cells of the organism and precipitation with LPS preparations. The inhibition experiments of the precipitations with various sugars and oligosaccharides suggested that the combining sites of these hybridoma antibodies were directed to an antigenic determinant structure containing----3 and----6 linked D-glucose, D-galactose, and N-acetyl-D-galactosamine.

Agglutination↗
PubMed1988

Studies of neurocirculatory effects of long-term L-threo-3,4-dihydroxyphenylserine administration in a patient with familial amyloidotic polyneuropathy.

The case is reported of a 57-year-old woman with familial amyloidotic polyneuropathy and concomitant orthostatic hypotension for which L-threo-3,4-dihydroxyphenylserine (L-threo-DOPS) was clinically effective. Testing of autonomic function under telemetric intra-arterial pressure monitoring before and during L-threo-DOPS treatment clearly demonstrated the pathophysiology of the sympathetic nervous system and its modification by L-threo-DOPS.

Amyloidosis↗