Search PubMed⌕ Search

Biomedical subjects

T Horiuchi

Publications and source records attributed to T Horiuchi.

At least 343 records · Page 19Linked to original sources
PubMed1991

Role of CD4 molecule in intrathymic T-cell development.

We have investigated the role of CD4 molecules in intrathymic T-cell repertoire selection. The administration of monoclonal antibody (mAb) to CD4 in organ culture of murine foetal thymus (FTOC) completely inhibited the development of CD4+8- cells, and additional treatment with anti-class II MHC (Ia) mAb caused no further effects on this inhibition. On the other hand, when the potentially autoreactive cells in Mls-1a mice were monitored by expression of the Mls-1a-reactive V beta 6 gene product of T-cell receptor alpha beta (TcR alpha beta), the treatment with anti-CD4 resulted in the appearance of V beta 6-bearing cells to some extent, but this effect was considerably reinforced by the combinatory use of anti-Ia mAb with anti-CD4. In a model system where the bacterial superantigen staphylococcal enterotoxin B serves as self-antigen to deplete V beta 8-bearing cells in FTOC, the depletion of V beta 8+ cells was restored partially by anti-CD4 alone but completely by the combination with anti-Ia. These results suggest that CD4 is indispensable for positive selection of all CD4+8- thymocytes, whereas participation of CD4 in negative selection is only partial. It was also observed that the development of TcR alpha beta-bearing cells in the CD4-8- population was inhibited by the treatment with anti-CD4 mAb. In Mls-1a mice, V beta 6-bearing cells were developed in CD4-8+, CD4+8+, and also in CD4-8- populations after anti-CD4 mAb treatment. It is suggested that TcR alpha beta-bearing CD4-8- cells are possibly originated from CD4+ cells and undergo CD4-mediated thymic selection.

Animals↗
PubMed1991

Development of a computer-aided surgery system: three-dimensional graphic reconstruction for treatment of liver cancer.

Simulation of the needle puncture and volume estimation for the tumors in the liver were carried out with the three-dimensional image reconstruction system, which consists of a medical image acquisition system, a data processing system, and a graphic display. A set of sliced-image data from a computerized tomography and/or a magnetic resonance imaging was used to reconstruct the liver, the vessels, and the tumors of the patients with liver cancer. A good agreement of anatomic locations of both the intrahepatic vessels and the tumors between the reconstructed liver model and the echography done intraoperatively was observed. Surgical simulations with these graphic models clearly indicated safety areas for needle puncture in the laser coagulation therapy. In addition liver volumes were calculated within 3% of error in comparison to the measured values. These results indicate that the computer-aided surgery system is a highly promising method that avoids cumbersome stereoscopic recognition of the anatomical location of the diseased area and the vessels, before and after surgery.

Aged↗
PubMed1991

[The effect of extradurally administered analgesics on somatosensory evoked eyelid microvibration in rabbits].

We examined the effect of various analgesics administered lumboextradurally or intravenously on acceleration of the eyelid microvibration (EMV) due to reflex contraction which was evoked by electrical stimulation of the sciatic and ulnar nerve in rabbits. No significant difference in the inhibition of EMV was observed initially between the sciatic nerve and the ulnar nerve stimulated group after 2 mg of morphine, administered either extradurally or intravenously. However, greater inhibition of EMV by the extradural morphine than by intravenous administration of this drug was observed after 10 min in sciatic nerve stimulated and after 20 min in the ulnar nerve stimulated group. With the extradural administration of 0.05 mg fentanyl, EMV was inhibited more significantly in the sciatic stimulated group than in the ulnar nerve stimulated group. Intravenous administration of this drug failed to reveal any change in either sciatic nerve stimulated or ulnar nerve stimulated group. When butorphanol 0.5 mg or buprenorphine 0.05 mg was administered, no significant difference in the inhibition of EMV was observed between the drugs, regardless of the routes of administration or sites of stimulation. Extradural administration of ketamine 0.5 mg showed none of the inhibition of EMV in both the sciatic nerve stimulated, and the ulnar nerve stimulated groups. These results indicate that various analgesics administered into the extradural space produced characteristic actions depending on the pharmacokinetic properties of each drug, locally and/or generally. In conclusion, monitoring of EMV can be a useful procedure for evaluation of the effect of analgesics.

Analgesia, Epidural↗
PubMed1991

[Studies on ocular blood circulation--effects of oxygen on choroidal circulatory disorders].

Experimental choroidal circulatory disorder was induced by diathermy coagulation in albino rabbit to investigate the effect of oxygen on choroidal blood flow in the area. Choroidal blood flow was measured by a hydrogen clearance method using electrolysis before and after the oxygen inhalation. Oxygen was inhaled for 30 minutes at 1 atmosphere using an open mask method in order to stabilize the arterial blood CO2 concentration. After inhalation of oxygen, normal choroidal blood flow showed a 24.9% decrease from control value, but no significant difference was seen in experimental choroidal circulatory disorder. These results suggested that the inner tissue metabolic CO2 inhibited the effect of vascular constriction in hyperoxemia.

Administration, Inhalation↗
PubMed1991

[Experimental study on avoidance of surgical heart block in septation for single ventricle].

A new method was developed to prevent surgical injury of the atrioventricular conduction system in septation for single ventricle. The new method includes the use of small Teflon pledgets to cover the conduction system at the crossing sites of suture line, and so that stitches can be placed on the pledgets to skip the conduction system. This paper describes the results of an experimental study to delineate the effects of covering pledgets on the morphology and function of the underlying conduction tissues. Deep hypothermia was employed for this experiment in 15 mongrel dogs. The small Teflon pledgets were sutured to bridge the endocardial surface of the atrioventricular node through the right atriotomy. They were subjected to sacrifice at 1 week to 12 months postoperatively. Electrophysiological study including electrocardiography. His bundle electrography and responsiveness of the atrioventricular conduction to rapid stimulation was done before the sacrifice. The resected heart was embedded in Ceroidin-Paraffin and serially sectioned for pathological study. No noticeable injuries were noted in the underlying conduction system. The electrophysiological study showed normal sinus rhythm at the time of sacrifice. No significant changes were noted in PQ intervals comparing to preoperative state. There were no significant differences in AH intervals, HV intervals and responsiveness to rapid atrial stimulation between experimental and normal control groups. In conclusion, the Teflon felt pledgets were demonstrated to have no detrimental effects on the atrioventricular conduction system in the chronic stage.

Animals↗
PubMed1990

Identification of 2Fe-2S cysteine ligands in putidaredoxin.

The iron-sulfur center of putidaredoxin is coordinated by four cysteine sulfhydrals. In order to determine which of the six cysteine residues in the protein coordinate the Fe-S center, we have individually mutated cysteine residues 73, 85 and 86 into serines. Of these mutant proteins, only C85S and C73S express holo-protein as evidence by SDS-PAGE and EPR spectroscopy. This leads us to the conclusion that residues 39,45,48, and 86 are the cysteines that coordinate the iron-sulfur center in putidaredoxin.

Base Sequence↗
PubMed1990

Translational regulation of complement protein C2 expression by differential utilization of the 5'-untranslated region of mRNA.

A recently isolated cDNA for human complement protein C2, C2HL5-3, has an unusually long 5'-untranslated region (UTR) containing four open reading frames upstream of the authentic initiation codon. Here we report that deletion of the 5'-UTR of C2HL5-3 resulted in a 10-fold enhancement in the translational efficiency of C2 in transient eukaryotic cellular assays. Elimination of the open reading frames in the 5'-UTR by site-directed mutagenesis of the initiation codons did not affect C2 synthesis in this assay system, indicating that other structural elements in this region are responsible for translational control. We also show that several C2 mRNAs of varying length in the 5'-UTR, including an alternative C2 mRNA expressing a considerably shorter 5'-UTR, are present in the liver and that the shorter C2 mRNA is the only C2 message found in U937 cells. These results suggest that tissue-specific utilization of alternative transcriptional start sites results in differential translational efficiencies of C2 and may provide insights into the tissue- and stimulus-specific regulation of eukaryotic gene expression.

Base Sequence↗
PubMed1990

Molecular mechanisms of replicational fidelity in Escherichia coli.

DNA polymerase III holoenzyme is responsible for chromosomal DNA synthesis in Escherichia coli and seems to be a major determinant of the fidelity of replication of this organism. Among ten different subunits of the holoenzyme, the alpha subunit, encoded by the dnaE gene, has a polymerase activity, while the epsilon subunit, encoded by the dnaQ gene, is a proofreader with a 3'-5' exonuclease activity. Using poly(dA)/oligo(dT)20 as a template-primer, misincorporation of dGMP, dCMP, and dAMP by the alpha subunit and exonucleolytic editing of those mispairs by the epsilon subunit were investigated. When the polymerization reaction was performed with the alpha subunit, dCMP and dGMP but not dAMP were misincorporated. This would suggest that the polymerase might have a base-selecting function to avoid dA:dA mispairing. A subassembly of the DNA polymerase III consisting of alpha, epsilon, and theta subunits misincorporated only dGMP. This would imply that the proofreading function of the epsilon subunit may correct the dC:dA but not the dG:dA mispair. Addition of a protein encoded by the mutT gene, defects of which cause AT to CG transversions in vivo, diminished the misincorporation of dGMP onto poly(dA) template by the alpha subunit. A dGTPase activity was associated with the MutT protein. The significance of the dGTPase activity in the prevention of dG:dA mispairing is discussed.

Bacterial Proteins↗
PubMed1990

Structural organization of the bovine adrenodoxin gene.

The gene structure of bovine adrenodoxin (Ad), a component of the steroid hydroxylating system in adrenal cortex mitochondria, was determined. This gene seems to be a single copy, but contains a pseudo exon in addition to the genuine gene region. The gene region for the active Ad is divided into 4 exons by 3 introns, and spans at least 27 kb. All the splice donor and acceptor sites follow the GT/AG rule. The transcription initiation site was determined by primer extension analysis, and putative TATA and GC boxes are present in the 5'-flanking region. A 12 base sequence, CCAGGGCCAGGG, is present 95 bases upstream from the transcription initiation site. A similar sequence was also found in the 5'-flanking regions of all genes for the steroid hydroxylating cytochromes P-450: P-450(SCC), P-450(11 beta), P-450(17 alpha), and P-450(C21), in the adrenal cortex. The consensus sequence for these five sequences is CGCAGGGCCATGGGA. The pseudo exon, exon 1', was present about 0.5 kb upstream from exon 1. It encodes the prepeptide region of the minor type Ad mRNA, but has a stop codon (TAA) in the frame. A TATA-box-like sequence and a CAAT-box-like sequence are also present in the 5'-flanking region of exon 1'. The GC content of exon 1 was over 80%, whereas for each of the other four exons, including exon 1', it was about 40%. Our observations suggest that exon 1, which encodes the prepeptide region of the major type Ad mRNA, has intruded into the region between exon 1' and exon 2.

Adrenodoxin↗
PubMed1990

A new approach for the filtrate regeneration system in the wearable artificial kidney.

In the filtrate and/or dialysate regeneration system, which is expected to miniaturize the artificial kidney, ammonium ion decomposed from urea by immobilized urease is removed competitively by ion-exchangers from coexisting cations. Since divalent cations such as Ca2+ and Mg2+ are more favorably exchanged than ammonium ion, this system needs supplementation of these cations and, thus, additional amount of ion-exchanger. To minimize these requirements, we utilized positively charged membrane to process cation-free filtrate in which urea is dialyzed. Positively charged membranes were tested in vitro to evaluate separation efficiency between urea and cations. Equilibrium adsorption of ammonium ion to ion-exchanger with or without co-existing cations demonstrates that this filtrate regeneration system can reduce the amount of ion-exchanger up to one-half to one-third of that of the conventional system. In an ex vivo experiment with a mongrel dog, blood urea nitrogen (BUN) concentration was maintained at the same level or up to 23% less than the initial value.

Aluminum Silicates↗
PubMed1990

Development of computer-aided motion analyzing (CAMA) system for radiopaque implanted tilting disk heart valves.

The newly developed semiautomatic data acquisition and processing system allows progress in quantitative evaluation of functions of implanted tilting disk valves. In the new system, data acquisition could be carried out semiautomatically by utilizing image processing methods, and the data analysis time was shortened. The system consists of a computer-controlled cinefilm loading device, a CCD camera, a frame memory, a superimposer, and CRT displays. Since series of the open- and shut-mode frames are commonly observed by turns in normal subjects, data acquisition was carried out manually at the first frame of each mode and semiautomatically from the second frame to the last. By processing the image data with the binarization method, the valve contours were detected, and an open angle and other motion properties can be obtained. Analyzing 90 frames of the cinefilm, this system analyzes data in a time period 20 min shorter than the manual procedure. With the implanted Medtronic Hall valve, a 60 to 65 degrees open angle was calculated.

Cineradiography↗
PubMed1990

A case of miliary tuberculosis with disseminated choroidal haemorrhages.

A 20-year-old Japanese man had generalised miliary tuberculosis. Although he had no ocular symptoms, choroidal miliary tuberculosis with pleomorphic findings, including disseminated choroidal haemorrhages, was noted in both fundi. The haemorrhages disappeared as the patient's condition improved on medical therapy. Disseminated choroidal haemorrhages should be looked for in patients with miliary tuberculosis.

Adult↗
PubMed1990

Epitope-specific regulation of the antibody response against alpha-lactalbumins in the mouse.

The immune responsiveness to human and bovine alpha-lactalbumin (HuALA and BoALA) was found to be under the control of immune response (Ir) gene(s) linked to the major histocompatibility complex. H-2k mice responded to both HuALA and BoALA, whereas H-2d,s,and f mice respond only to HuALA; H-2b mice were nonresponders to both HuALA and BoALA. A survey with B10.A recombinant mouse strains enabled us to map the Ir gene in the I-A subregion. The responsiveness was shown to be dominant in F1 mice. The coimmunization of BoALA and HuALA resulted in the suppressed secondary antibody response to HuALA in B10.S (H-2s) and BALB/c (H-2d) but not in C3H (H-2k) suggesting that the low responsiveness against HuALA in these strains is due to an active suppression. The transfer of splenic T cells of B10.S mice primed with BoALA into syngeneic animals suppressed the response to HuALA. T cells specific for a particular epitope present on BoALA appeared to suppress the immune response to other epitopes on HuALA. Thus, the presence of epitope-specific suppressor T cells seems to account for this Ir-gene-controlled low responsiveness to ALA in H-2s mice.

Amino Acid Sequence↗
PubMed1990

Surface and tissue forces, surfactant protein A, and the phospholipid components of pulmonary surfactant in bleomycin-induced pulmonary fibrosis in the rat.

Administration of bleomycin to animals results in an alteration of the pressure-volume relationship of the lungs with an increased elastic recoil at any given volume. We sought to evaluate the relative importance of surface forces to elastic recoil by comparing the differences between the air and saline pressure-volume curves. The difference in elastic recoil between air- and saline-filled lungs was altered in bleomycin-treated rats when elastic recoil was compared at 35% of predicted TLC or at 80% of observed TLC. This pressure difference was present both during the early phase (Days 4 and 7) of the injury and acute inflammation as well as during the later phase (Days 14 to 28) when there was chronic inflammation and an elevation in the lung hydroxyproline content. The total amount of phospholipids recovered in lavage was decreased at Day 4 and increased more than 2.5-fold over saline-instilled control animals at Days 21 and 28. The percentage of phosphatidylglycerol was reduced and that of phosphatidylinositol increased. There was no consistent change in the percentage of phosphatidylcholine that was disaturated. The amount of surfactant protein A (SP-A) did not change during the course of the experiment and was not a useful independent marker of alveolar injury or changes in pulmonary compliance. The ratio of SP-A to total phospholipid decreased 14 to 28 days after instillation of bleomycin. These results support the hypothesis that individual components of surfactant are independently regulated and indicate that SP-A content in lavage is insensitive to lung injury and repair.

Animals↗
PubMed1990

Effects of cyclosporin A on T-cell development in organ-cultured foetal thymus.

The effects of cyclosporin A (CsA) on T-cell development were assessed in an organ culture of murine foetal thymus. Applying three-colour flow cytometric analysis, we showed that the agent inhibits the development of mature CD3/T-cell receptor alpha beta (TcR alpha beta)+ cells both in CD4+8- and CD4-8+ populations. CD4-8- cells appeared to be accumulated by CsA. We examined the heterogeneity of CD4-8- cells generated in the organ culture, and defined five subpopulations by the expression of the cell-surface molecules CD3/TcR, J11d and CD25. It has been demonstrated that only the CD3/TcR alpha beta+ J11d- CD25- subpopulation is susceptible to the suppressive effects of CsA among CD4-8- cells, whereas all the other four subpopulations, including CD3/TcR gamma delta+ cells, are resistant. Thus, all of the TcR alpha beta-bearing cells, including CD4-8- cells but none of the TcR alpha beta- cells, are CsA sensitive. Because it is known that CsA inhibits the TcR-mediated signalling events in mature T cells and that signallings mediated via the interaction of TcR with major histocompatibility complex (MHC) molecules on thymic stroma cells are crucial for thymic selection of T cells, these results indicate that TcR alpha beta-bearing CD4-8- cells but not TcR gamma delta-bearing CD4-8- cells undergo thymic positive selection.

Animals↗
PubMed1990

[A new experimental model of pulmonary hypertension in dog using an adjustable pulmonary artery band].

In order to study pathogenesis, reversibility, and treatment of pulmonary hypertension in congenital heart disease, a new experimental model to induce pulmonary vascular diseases has been designed. Previous models by other investigators were anastomosis between a systemic artery and pulmonary artery of one lung lobe, and these could not provide constant induction of pulmonary vascular diseases. Furthermore the postoperative mortalities in their experiences were quite high and acute iatrogenic pathological changes such as bleeding, edema and emphysema developed in the pulmonary vasculature and parenchyma of the anastomosed lobe. Use of our adjustable pulmonary artery band has eliminated such unwanted complications. The surgical procedure includes an end-to-side anastomosis of the left main pulmonary artery to the descending thoracic aorta, and banding of the anastomosed pulmonary artery using the adjustable band. The band was gradually loosened by extrathoracic manipulation during three to four weeks observation after operation. This technique provided dogs to survive sufficiently long enough and with a high success rate, and to produce extremely advanced pulmonary vascular diseases. Of the twenty dogs operated such, eighteen survived the first postsurgical week and thirteen dogs developed hypertensive pulmonary vascular diseases. Development of the medial hypertrophy was evident at one week and gradually advanced. In eight weeks, intimal cellular proliferation (Grade 2 of the Heath & Edwards' classification) became apparent. In twelve weeks, the intimal proliferation became fibrous and acellular (Grade 3) and caused complete obstruction of the lumen of some muscular arteries. In twenty weeks specimen, typical plexiform lesions (Grade 4) and dilatation lesions (Grade 5) involved the small muscular arteries in the whole left lung.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Surface ultrastructure of newly excysted metacercariae of Paragonimus heterotremus.

The newly excysted metacercariae of P. heterotremus were examined by scanning electron microscopy (SEM). Large dome-shaped papillae, small ones with a pit, and small ones with a smooth surface were observed around the suckers. The number of the small dome-shaped papillae with a pit was about 30 around the oral sucker and that of the small ones with a smooth surface varied from 9 to 13 around the ventral sucker. The present report is the first record of excysted metacercariae of P. heterotremus examined by SEM.

Animals↗