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Biomedical subjects

K Aoyama

Publications and source records attributed to K Aoyama.

At least 73 records · Page 4Linked to original sources
PubMed1998

Within-session response rate in rats decreases as a function of amount eaten.

In past studies, within-session changes of rat feeding behavior were always treated as functions of time. This study aimed to describe the within-session decreases of operant response as a function of cumulative amount of food intake. Rats (n = 8) were trained to obtain food pellets by lever-press responses. Session lengths were 45 min. The following results were observed: 1) Response rates during a CRF schedule were well described as a linear function of cumulative amount of food pellets eaten; 2) The linear equation was also accurate in describing the response rates during a semi-VI schedule; and 3) Even if schedules of reinforcement were changed within a single session, response rates in each reinforcement schedule were well described as linear functions of cumulative food intake. Thus, response rates decreased proportionally to the increase in cumulative amount of food intake.

Algorithms↗
PubMed1998

Interleukin-12 enhances contact hypersensitivity by modulating the in vivo cytokine pattern in mice.

It has been proven that interleukin-12 (IL-12) can modify Th1 and Th2 cell-mediated immune diseases by altering the development and cytokine production of the cells. In this study, we investigated the in vivo immunomodulatory effect of recombinant murine IL-12 on contact hypersensitivity, a Th1 cell-mediated disease. For this purpose, Balb/C mice were sensitized with 3% 4-ethyoxymethylene-2-phenyl-oxazol-5-one (OXAZ), and recombinant mouse IL-12 was given simultaneously during the induction phase. Contact allergy was then elicited by ear challenge with 1% OXAZ. We examined the mouse ear swelling response, in vivo cytokine gene expression in the skin and local lymph nodes, and in vitro cytokine production by the spleen lymphocytes. It was found that in vivo IL-12 treatment during the induction phase significantly enhanced the ear swelling response to OXAZ in sensitized mice. Moreover, remarkable mononuclear cell infiltration and edema and higher expression of Th1 cytokine mRNAs (IL-2 and interferon-gamma) in the skin lesion and local lymph nodes were observed in contact allergic mice with IL-12 treatment compared with contact allergic mice without IL-12 treatment. The expression of Th2 cytokine mRNA (IL-4) in the skin lesion and local lymph nodes, however, was largely downregulated, with no change in IL-5 mRNA in IL-12-treated contact allergic mice. We found, unexpectedly, that, similar to the effects on phytohemagglutinin (PHA) stimulated in vitro IL-2 and IFN-gamma production, PHA-induced in vitro IL-4 production was enhanced in the spleen lymphocytes from IL-12-treated contact allergic mice. Our results indicate that exogenous IL-12 enhanced contact hypersensitivity probably because of the in vivo promoting and suppressing effects of IL-12 on Th1 and Th2 gene expression, respectively.

Animals↗
PubMed1998

Expression of interleukin-18 in murine contact hypersensitivity.

In this study, we made a mouse model for contact hypersensitivity (CH) using oxazolone as a contact allergen and examined the expression of interleukin-18 (IL-18) in the diseased skin sites at both mRNA and protein levels. In the kinetic study by semiquantitative RT-PCR, IL-18 mRNA was constitutively produced in normal murine skin but increased significantly at 12 h and peaked at 24 h in the ear skin of CH mice. A positive correlation was confirmed between the IL-18 mRNA signal and CH, as measured by mouse ear swelling response. Histologically, in situ hybridization showed that the IL-18 mRNA signal was weakly observed in the dermis but not the epidermis of normal skin, whereas the IL-18 mRNA signal was found intensively in the dermis, particularly in inflammatory cell areas. Using IL-18-specific antibody immunostaining, it was further found that IL-18 protein production had a histologic location similar to that of IL-18 mRNA in both normal and CH mice. The present study suggests that IL-18 may be implicated in the pathogenesis of murine CH.

Animals↗
PubMed1998

[A case of cyclosporin responsive myasthenia gravis with an invasive thymoma].

We report a patient with myasthenia gravis (MG) accompanied by invasive thymoma which we treated with cyclosporin. The patient was a 42-year-old woman who was admitted to our hospital because of diplopia and left blepharoptosis. Thymectomy was undertaken but it was incomplete because the thymoma had already invaded other tissues. Following thymectomy, the antibody level for acetylcholine receptors (AChR) gradually increased and generalized weakness and dyspnea emerged. The symptoms did not improve with ADOC chemotherapy and steroid pulse. Treatment with cyclosporin (200 mg/day) was initiated after plasmapheresis and the symptoms improved and AChR antibody levels subsided. There has not been a recurrence of the thymoma after 28 months. In conclusion, treatment with cyclosporin may be more effective than other treatments in patients with inveterate MG that is accompanied by thymoma.

Adult↗
PubMed1997

Matrix glycoprotein SC1/ECM2 augments B lymphopoiesis.

The extracellular matrix produced by stromal cells plays a critical role in lympho-hematopoiesis. It was recently discovered that matrix glycoprotein SC1/ECM2 is a component of that matrix and preliminary evidence suggested that it could contribute to the nurturing environment for B-lymphocyte precursors. A fusion protein prepared from the amino terminal portion of SC1/ECM2 and the constant region of human Ig preferentially bound to pre-B cells. Furthermore, the cloning efficiency of interleukin-7-dependent B-cell precursors was increased in a dose-dependent manner by addition of this fusion protein. We now report the complete cDNA sequence for murine SC1/ECM2 and its localization to the central region of chromosome 5. A fusion protein prepared from the full length of SC1/ECM2 and Ig was found to recognize pre-B cells in a divalent cation-dependent manner, and to augment mitogen-dependent proliferation of mature B cells, as well as the cloning of pre-B cells, but to have no influence on myeloid progenitor cells. Although SC1/ECM2 is normally a secreted protein, we show that it is also capable of augmenting lymphopoiesis when expressed as a transmembrane protein on fibroblasts. Although the C-terminal portion of SC1/ECM2 has sequence homology to osteonectin/SPARC, the unique N-terminal one fifth of the protein was sufficient to augment lymphocyte growth.

Activated-Leukocyte Cell Adhesion Molecule↗
PubMed1997

Generation of neutralizing antibody to the reverse transcriptase of human immunodeficiency virus type 1 by immunizing of mice with an infectious vaccinia virus recombinant.

Antibodies inhibiting the reverse transcriptase (RT) of human immunodeficiency virus type-1 (HIV-1) were found to be generated in the serum of mice repeatedly infected with a vaccinia virus recombinant, WRRT, expressing the enzyme. A monoclonal antibody (mAb), 7C4, which specifically and almost completely inhibits the RNA-dependent DNA polymerase activity of HIV-1 RT was produced from a mouse repeatedly immunized with WRRT. 7C4 seems to be specific for HIV-1 among retroviruses: 7C4 inhibited RT activity of three strains of HIV-1 (IIIB, Bru, and IMS-1) but not of two strains of HIV-2 (GH-1 and LAV-2) or two strains of SIV (MAC and MND). The immunoglobulin isotype of three out of four mAbs produced from spleen cells of the immunized mouse were IgG2a. This immunization method that avoids protein denaturation may preferentially induce a T helper type-1 immune response and increase the chances of producing the only occasionally obtainable mAb capable of recognizing a conformational epitope and completely inhibiting enzyme activity.

Animals↗
PubMed1997

Characterization of an extremely thermophilic and oxygen-stable membrane-bound hydrogenase from a marine hydrogen-oxidizing bacterium Hydrogenovibrio marinus.

The membrane-bound hydrogenase from a marine hydrogen-oxidizing bacterium Hydrogenovibrio marinus was characterized as highly oxygen-tolerant, extremely thermophilic and thermostable in its membrane-bound form. The optimum temperatures for H2 oxidation and H2 evolution were 90 and 80 degrees C, respectively. The enzyme retained 90% of its activity after heating at 70 degrees C for 50 min under air and retained full activity at 90 degrees C for 80 min under hydrogen. The optimum pH values were 5.5 (H2 evolution) and 9.4 (H2 oxidation), and the activity ratio (H2 evolution/H2 oxidation) was high (50.3) at pH 5.5. The hydrogen evolution from reduced methyl viologen continued at high temperatures and acidic pH with the continuous addition of sodium dithionite.

Cell Membrane↗
PubMed1997

Pharmacokinetics of recombinant human interleukin-11 (rhIL-11) in healthy male subjects.

AIMS: To study the pharmacokinetics of recombinant human interleukin-11 (rhIL-11) in healthy male volunteers following subcutaneous (s.c.) and intravenous (i.v.) administration. METHODS: RhIL-11 was infused intravenously at 10-50 micrograms kg-1 for 1 or 3 h, or administered subcutaneously at 3-50 micrograms kg-1 to volunteers. RhIL-11 was also administered at 3 micrograms kg-1 s.c. once daily for 7 days. Plasma and urinary concentrations were measured by enzyme-linked immunosorbent assay (ELISA). RESULTS: RhIL-11 showed linear pharmacokinetics after both intravenous infusion and s.c. administration. Comparison of t1/2 and MRT values after i.v. administration with those after s.c. administration indicated that rhIL-11 pharmacokinetics after s.c. administration were absorption rate-limited. Bioavailability after s.c. administration was about 65%. Since RhIL-11 was not detected in urine after a single 50 micrograms kg-1 s.c. dose, rhIL-11 was considered to be eliminated by metabolism. There was no significant change in the pharmacokinetic profile of rhIL-11 following repeated s.c. administration. CONCLUSIONS: RhIL-11 demonstrated linear pharmacokinetics at these dose ranges after single and repeated s.c. administration or constant-rate i.v. infusion in healthy volunteers.

Adolescent↗
PubMed1997

Ocular surface disorders in the critically ill.

Abnormalities of the cornea and conjunctiva occur in association with neurological diseases, nocturnal lagophthalmos, coma, infection, and mechanical ventilation. We investigated the incidence and causes of ocular surface disorders in critically ill patients. In a retrospective study, the presence of conjunctivitis and corneal erosion was determined by reviewing the medical charts of 143 mechanically ventilated patients (intensive care unit [ICU] stay > or =7 days). In the subsequent prospective study, 15 patients who had sedatives or muscle relaxants administered continuously for more than 48 h in the ICU were investigated. Corneal erosion was examined using a slit lamp once a day. Ocular surface disorder was found in 28 of the 143 patients (20%) whose ICU stay exceeded 7 days. The incidence increased with continuous sedation (35% vs 15%). The incidence also increased with continuous neuromuscular blockade (39% vs 11%). In the prospective study, nine patients (60%) developed corneal erosion. A patient's inability to fully close his or her eyes increased the incidence (P < 0.01) of corneal erosion. Protective eyelid taping was effective in preventing and treating the corneal erosion. In conclusion, the critically ill often develop ocular surface disorders, especially when sedated and immobilized. A close relationship was observed between these conditions and the inability to close one's eyes.

Adolescent↗
PubMed1996

Electrotransformation of lactobacillus acidophilus group A1.

Two strains of Lactobacillus acidophilus Group A1, the neotype ATCC 4356 and a human isolate NCFM-N2, widely used as a dietary adjunct in milk and cultured dairy products, were transformed with plasmid DNA by electroporation. The transformation characteristics exhibited by the two L acidophilus strains were found to differ markedly even though they appeared similar at the genomic level based on the DNA patterns of SmaI restriction fragments. To our knowledge, this is the first report of a consistent, reproducible transformation system of Lactobacillus acidophilus strains comprising the A1 DNA homology group.

DNA, Bacterial↗
PubMed1996

2-D Crystallization of the Rhodococcus 20S Proteasome

The 2D crystallization method using a liquid-liquid interface has been applied to the Rhodococcus 20S proteasome. Two types of ordered arrays were obtained, both large enough for high-resolution analysis. The first one is a hexagonal close-packed array, whereas the second one has fourfold symmetry. By image analysis based on a real space correlation averaging technique, the close-packed array was found to be hexagonally packed but the molecules had complete rotational freedom. The fourfold array is, however, a true crystal with p4 symmetry. Lattice constants are a = b = 20.0 nm and the unit cell of this crystal contains two proteasomes. The diffraction pattern computed from the original picture shows the spots up to (4.5) that correspond to 3.1 nm resolution. After applying an unbending procedure, the diffraction pattern shows spots extending to 1.8 nm resolution.

Journal Article↗
PubMed1996

Cricoid pressure impedes positioning and ventilation through the laryngeal mask airway.

PURPOSE: To assess the effect of cricoid pressure on the positioning of and ventilation through the laryngeal mask airway (LMA). METHODS: In a double-blind, randomized design, the LMA was inserted with (CP[+] group, n = 20) or without double-handed cricoid pressure (CP[-] group, n = 20). Ventilation through the LMA was assessed by measuring expiratory tidal volume and judged as adequate when a mean expiratory tidal volume of > or = 10 ml.kg-1 could be obtained. The LMA position was examined by fibreoscopy. The position of the mask relative to the cricoid cartilage and the cervical spine was radiologically examined (n = 10 in each group). RESULTS: Ventilation was adequate in all patients in the CP[-] group but in only five patients (25%) of the CP[+] group (P < 0.001). The glottis was visible fibreoptically below the mask aperture in all patients in the CP[-] group, but in only three patients in the CP[+] group (P < 0.001). Fibreoscopy showed that the mask was not inserted far enough in the remaining 17 patients of the CP[+] group. The reason for unsuccessful ventilation in the CP[+] group was excessive gas leakage (n = 2) and/or partial or complete airway obstruction (n = 13), which was noted fibreoptically. The radiographs showed that the tip of the mask in the CP[-] group was located below the level of the cricoid cartilage (C6 or C7 vertebra). The mask tip in the CP[+] group was above this level (C4 or C5 vertebra) (P < 0.01). CONCLUSION: Cricoid pressure impedes positioning of and ventilation through the LMA.

Adult↗
PubMed1996

Cranial attachment of the gubernaculum associated with undescended testes.

Elongated epididymis is an abnormality encountered most frequently in patients who have an undescended testis (or testes). To clarify the implication of this anomaly in testicular descent, the anatomic configuration of paratesticular structures, especially the site of cranial attachment of the gubernaculum in relation to the configuration of the vas deferens, was evaluated in 54 undescended testes of 44 patients. Undescended testes were associated with an elongated epididymis in 42.5% of cases. Of these, the cranial gubernaculum was attached solely to the vas deferens in 73.9%. In this group, the cranial gubernaculum was attached to the most descended part of the loop of the vas deferens. No patient with a nonelongated epididymis had a gubernaculum attached solely to the vas deferens. These results suggest that the abnormal attachment of the cranial gubernaculum in the embryological stage might affect the mode of descent of adjacent paratesticular structures.

Child↗
PubMed1996

Electron holographic observation for biological specimens: electron holography of bio-specimens.

Electron holography has been applied to the observation of biological filaments. The technique has some advantages over conventional imaging for observing weak-phase objects such as small unstained biological structures. To avoid artificial structural transformation of the sample owing to the interaction with the supporting film, a holey carbon film was used to support the filaments. A tobacco mosaic virus bridged over a hole was observed as a cylindrical shape; the contrast distribution across the filament represents its actual shape, which is difficult to obtain with conventional transmission electron microscopy. A number of technical limitations which at present prevent high-resolution structure analysis of biological macromolecules by electron holography are discussed in this report.

Electrons↗
PubMed1996

Use of the fibrescope-video camera system for difficult tracheal intubation.

We describe an alternative technique for difficult intubation using a fibrescope and a video camera system. The fibrescope attached to the video camera was passed nasally, which provided a view of the larynx on the monitor screen. Then the operator inserted a tracheal tube into the trachea orally using a second fibrescope or a stylet under video visual control. This technique permits a view of the tube passing through the vocal cords in patients who present difficulty in intubation.

Fiber Optic Technology↗
PubMed1996

Performance of commercial cultures in fluid milk applications.

Six Lactobacillus acidophilus, 5 Bifidobacterium, and 6 Streptococcus thermophilus strains were studied for characteristics that are important to activity and stability in unfermented fluid milk products. Speciation, strain relatedness, frozen concentrate stability, bile sensitivity, and lactase activity were evaluated. The microbiological stability of a culture-containing fluid milk product was also determined. Two of the bifidobacteria cultures contained > 1 strain. Some strains were shown to be closely related or identical by pulsed-field gel electrophoresis of fragmented chromosomal DNA. Selective media that distinguished among all 3 added genera were identified. All lactobacilli and most of the bifidobacteria were resistant to bile concentrations varying from 1 to 3%, and all streptococci were sensitive to bile. Lactase activities were highest for S. thermophilus strains, supporting use of this species in fluid milk and dairy products to aid in the digestion of lactose by consumers. The experimental product evaluated in this study contained 10(7) cfu/ml of both L. Acidophilus and Bifidobacterium spp. and 5 x 10(7) cfu/ml of S. thermophilus. Lactic, but not psychrotrophic, populations were fairly stable during storage. The results suggest that milk formulated with high concentrations of three different genera of probiotic bacteria can be manufactured with commercial strains.

Animals↗