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T Azuma

Publications and source records attributed to T Azuma.

At least 307 records · Page 17Linked to original sources
PubMed1988

Vortex generation in pulsatile flow through arterial bifurcation models including the human carotid artery.

Visualization experiments were performed to elucidate the complicated flow pattern in pulsatile flow through arterial bifurcations. Human common carotid arteries, which were made transparent, and glass-models simulating Y- and T-shaped bifurcations were used. Pulsatile flow with wave forms similar to those of arterial flow was generated with a piston pump, elastic tube, airchamber, and valves controlling the outflow resistance. Helically recirculating flow with a pattern similar to that of the horseshoe vortex produced around wall-based protuberances in circular tubes was observed in pulsatile flow through all the bifurcations used in the present study. This flow type, which we shall refer to as the horseshoe vortex, has also been demonstrated to occur at the human common carotid bifurcation in steady flow with Reynolds numbers above 100. Time-varying flows also produced the horseshoe vortex mostly during the decelerating phase. Fluid particles of dye solution approaching the bifurcation apex diverged, divided into two directions perpendicularly, and then showed helical motion representing the horseshoe vortex formation. While this helical flow was produced, the stagnation points appeared on the wall upstream of the apex. Their position was dependent upon the flow distribution ratio between the branches in the individual arteries. The region affected by the horseshoe vortex was smaller during pulsatile flow than during steady flow. Lowering the Reynolds number together with the Womersley number weakened the intensity of helical flow. A separation bubble, resulting from the divergence or wall roughness, was observed at the outer or inner wall of the branch vessels and made the flow more complicated.

Adult↗
PubMed1988

[Multidisciplinary, intra-arterial chemotherapy (IAC) with CDDP and 5-FU against cervical cancer].

As one method of multidisciplinary treatment for cancer of the uterine cervix, a combination IAC using CDDP and 5-FU was applied. Six operable and three inoperable, advanced patients were treated with a single 100-120 mg/body IAC bolus of CDDP followed by a continuous IA infusion of 2,500 mg/body of 5-FU. This was combined with surgical therapy in the former group and radiotherapy in the latter group. In operable cases, the extirpated tissues were examined histopathologically for effects of the combination IAC. Microscopic findings included atrophy and swelling of the cancer cell nucleus, plus variable diffused reduction of the cancer cell nest accompanied by vacuolation of the cytoplasm. In inoperable cases, observations carried out by graphical scintigram, and clinical investigation at 10 days after the IAC, indicated improved conditions. Among the adverse reactions, renal dysfunction recovered two weeks after IAC. No evidence of severe myelosuppression was observed. Therefore, IAC with CDDP and 5-FU, plus surgery or radiotherapy, against carcinoma of the cervix had favorable laboratory and clinical results.

Adult↗
PubMed1987

Secretion and biosynthesis of COOH-terminal glycine extended progastrin (gastrin-G) in rat gastric antrum.

The effects of serotonin (5-HT) on gastrin and COOH-terminal glycine extended progastrin (gastrin-G) secretion, biosynthesis of gastrin and gastrin-G, and the effects of gastrin-G on gastric acid secretion were examined in rats. 5-HT 10(-5) M significantly stimulated gastrin and gastrin-G secretion. Atropine 10(-6) M, which abolished the effects of cholinergic agent to stimulate gastrin secretion, blocked the 5-HT-stimulated gastrin and gastrin-G secretion. In biosynthesis of gastrin and gastrin-G the peak of 35S radioactivity appeared in gastrin-G immunoreactive peak at 30 minutes incubation, however, 35S radioactivity did not appear in the gastrin immunoreactive peak until 1 hour chase incubation. The peak of 35S radioactivity transferred from the gastrin-G immunoreactive peak to the gastrin immunoreactive peak. Concerning the bioactivity of gastrin-G, it did not stimulate gastric acid secretion. From these findings we may conclude that serotoninergic neurons act as interneurons which themselves stimulate a second neuron stimulatory to gastrin and gastrin-G secretion, the posttranslational processing of gastrin occurs sequentially through the proteolytic processing of progastrin to glycin extended processing intermediates, gastrin-G, followed by activation via alpha-amidation in secretory granules, gastrin-G co-secreted with gastrin does not have biological activity, PAM activity in serum does not play a functional role under physiological conditions.

Animals↗
PubMed1987

Immunocytochemical characterization of monoclonal antibody A2B5 in the rat gastric antrum.

Immunocytochemical characterization of monoclonal antibody A2B5 was carried out in the rat gastric antrum, in which immunoreactive cells were found mainly around the middle of the pyloric glands. In serial sections, most cells were identified as gastrin cells, but only 60.6 + 5.9% (mean + SD, n = 5) of them reacted with the antibody. Somatostatin cells did not react with antibody A2B5. The different reaction of antibody A2B5 to gastrin cells indicated that gastrin cells may have a variety of cell surface receptors and have different physiological functions. From these findings, it was concluded that antibody A2B5 did not satisfy the requirements for the cell surface marker of gastrointestinal endocrine cells, though it could be useful in studies of cell surface receptors, concerning which little is known about gastrointestinal endocrine cells.

Animals↗
PubMed1987

Effects of bombesin on the release of glycine-extended progastrin (gastrin G) in rat antral tissue culture.

Recently, glycine-extended processing intermediates of progastrin were identified in porcine stomach using a radioimmunoassay with conventional polyclonal antisera developed against a synthetic peptide analogue for progastrin processing intermediates, gastrin 6-G(Tyr-Gly-Trp-Met-Asp-Phe-Gly). We developed monoclonal antibodies specific for glycine-extended processing intermediates of progastrin (gastrin G). Monoclonal antibody 109-21 appeared to require the carboxyl-terminal pentapeptide structure of gastrin 6-G for maximal binding. Cross-reactivities of 109-21 against gastrin 17 I, gastrin 17 II, cholecystokinin-octapeptide, des(SO3) cholecystokinin-octapeptide, and gastrin 6-G-R-R were respectively 1%, less than 0.1%, less than 0.1%, 0.1%, and 0.5%. With this monoclonal antibody and a polyclonal gastrin antibody we examined the concentrations of gastrin and gastrin G in tissue and the effects of bombesin on the release of gastrin and gastrin G from rat antral mucosa in tissue culture. The gastrin G to gastrin ratio was 2.2 in rat antral mucosa and 0.66 in rat duodenal mucosa. In tissue culture, bombesin significantly stimulated gastrin and gastrin-G secretion at doses of 10(-8) and 3 X 10(-8) M. Atropine (10(-6) M) abolished the actions of carbachol to stimulate gastrin and gastrin-G secretion but had no effect on bombesin-stimulated gastrin and gastrin-G secretion. These results suggest that gastrin G is cosecreted with gastrin in response to carbachol and bombesin, and the stimulation of gastrin and gastrin-G secretion by bombesin does not involve cholinergic neural pathways and may reflect a direct action on gastrin cells.

Animals↗
PubMed1987

Alpha 2-adrenergic receptor in familial amyloidotic polyneuropathy.

alpha 2-Adrenergic receptor binding has been studied in platelet membranes from 16 patients with type 1 familial amyloidotic polyneuropathy (FAP) at various clinical stages and 15 normal subjects. Binding of the radioligand [3H]yohimbine to platelet membranes was used to examine alpha 2-adrenergic receptors. The number of alpha 2-adrenergic receptors were significantly lower in patients of the early stage than in normal subjects. Then, the numbers tended to be higher than those of normal subjects in the intermediate stage, and they were higher in the single advanced-stage patient studied. The reduction in alpha 2-adrenergic receptor numbers in platelet membranes from patients of the early stage might be explained by the down-regulation of the receptors in vascular smooth muscle, but it remains uncertain whether a high number of alpha 2-adrenergic receptors observed in the single advanced-stage patient might be explained by the up-regulation of the receptors.

Adult↗
PubMed1987

Maturation of the immune response to (4-hydroxy-3-nitrophenyl)-acetyl (NP) haptens in C57BL/6 mice.

Changes with time in specificity and affinity of anti-NP antibodies in C57BL/6 mice after immunization with NP22-chicken gamma-globulin (CGG) were studied by comparing the abilities of the antibodies to bind to NP3-bovine serum albumin (NP3-BSA) at pH 5 and 8. Early anti-NP antibodies (on day 14 after immunization) bound to NP3-BSA at pH 8, but not pH 5. This pH-dependence of binding was explained in terms of the low affinity of the antibody to the phenolic form of NP on the basis of results of fluorescence quenching titration of a monoclonal anti-NP antibody that showed similar specificity to that of the early anti-NP antibodies. Since NP on the CGG molecule ionized with an apparent pK of about 7.4, more than half the NP should be in the unionized (phenolic) form under the immunization conditions. However, early anti-NP antibodies bound preferentially to the ionized (phenolate) form of NP, which was a minor form at neutral pH, whereas later anti-NP antibodies showed ability to bind to both the phenolate and phenolic forms of NP. This change in specificity with time was observed on immunization with T cell-dependent (TD) antigens such as NP-CGG and NP keyhole limpet hemocyanin (KLH), but not with a T cell-independent (TI) antigen such as NP-Ficoll. The heavy (H) chains from the two monoclonal antibodies 3G6 and 3C6, which bound to the phenolate form and both the phenolate and phenolic forms, respectively, were recombined with lambda 1 chains (L3G6 and L3C6) from these antibodies as well as a lambda 1 chain (LHOPC-1) with the amino acid sequence of the germline. Ability to bind to the phenolate form of NP was recovered in all the reconstituted IgGs, while ability to bind to both the phenolate and phenolic form of NP was observed only with IgG reconstituted from H3C6 and L3C6. These results suggest that the specificity corresponding to early anti-NP antibodies were generated even by lambda 1 chains of a germline sequence, but that of late anti-NP antibodies was expressed only by an appropriate pair of H and L chains. The contribution of amino acid substitution by somatic point mutation to the change of specificity with time was discussed.

Animals↗
PubMed1987

Biliary penetration of cefbuperazone in the presence and absence of obstructive jaundice.

In thirteen patients with normal liver function, the mean concentrations of cefbuperazone in hepatic bile, gall bladder bile and gallbladder tissue 30 min after injection were 1134.8 +/- 36.8 (mean +/- S.E.M.) mg/l, 6.6 +/- 3.0 mg/l and 26.1 +/- 7.6 mg/l, respectively. In patients with obstructive jaundice, cefbuperazone concentrations in bile were 99 +/- 29.2 mg/l (mean +/- S.E.M.) 1 h post-dose and decreased to 13.9 +/- 5.1 mg/l 6 h post-dose. In both groups of patients biliary concentrations of cefbuperazone were higher than the MICs of most organisms causing biliary infection.

Bile↗
PubMed1987

Specificity change of antibody to (4-hydroxy-3-nitrophenyl)acetyl haptens by somatic hypermutation.

Change in the specificity of anti-(4-hydroxy-3-nitrophenyl)acetyl (NP) antibodies (Abs) with time after immunization was studied. The early anti-NP Abs was specific to the ionized (phenolate) form of NP. The specificity changed with time and the late Abs became able to bind to the protonated (phenolic) form as well as the phenolate form of NP. The nucleotide sequences of mRNA coding for variable regions of heavy and light chains suggested that somatic hypermutation contributed to this change of the specificity.

Animals↗
PubMed1987

Usefulness of selective arterial secretin injection test for localization of gastrinoma in the Zollinger-Ellison syndrome.

Secretin was injected into a feeding or nonfeeding artery of a gastrinoma and blood samples were taken from the hepatic vein (HV) or a peripheral artery (PA) to measure the changes of serum immunoreactive gastrin concentration (IRG). The IRG in the HV rose within 40 seconds and in the PA rose within 60 seconds after the injection of secretin into a feeding artery, but not after secretin was injected into a nonfeeder. These results indicated that secretin directly stimulates a gastrinoma to release gastrin in vivo. The selective arterial secretin injection test (SASI test) was applied in three patients in whom gastrinomas could not be located by computed tomography, ultrasonography, or arteriography, and functioning gastrinomas were located in all three patients. In one patient, malignant gastrinomas in the head of the pancreas and in the duodenum could be resected radically with the help of this test.

Adult↗
PubMed1987

Diagnosis of familial amyloidotic polyneuropathy: isolation of variant prealbumin.

A novel, small-scale method was developed for detecting carriers of a prealbumin variant associated with type 1 familial amyloidotic polyneuropathy (FAP). Prealbumin isolated from plasma by a two-step preliminary chromatographic procedure was further separated into two peaks by reverse-phase high-performance liquid chromatography. The normal and variant prealbumins were identified by secondary ion mass spectrometry. The procedure is relatively simple, reliable, and applicable to the definitive diagnosis of FAP in affected patients and also as a preclinical test for the offspring of patients with FAP.

Adolescent↗
PubMed1987

Characteristics of secondary flow in steady and pulsatile flows through a symmetrical bifurcation.

Steady and pulsatile flow in a glass model simulating an arterial bifurcation was investigated by flow visualization techniques. Secondary flow generated at the bifurcation has a similar pattern to a vortex, called the horseshoe vortex, produced around a wall-based protuberance in a circular tube. The same flow disturbance was clearly observed during the decelerating phase of pulsatile flow. The vortex produces a stagnation point on the top and bottom wall just upstream from the bifurcation apex. When aluminium dust was suspended in the test fluid perfusing the blood vessel model, particles deposited over an area spreading from the stagnation point to the lateral corners of the bifurcation. Comparison between the present results and topographical patterns of atherosclerosis reported in the literature suggests that it is in such low shear regions that lipid deposition tends to occur most.

Arteries↗