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Biomedical subjects

Atsushi Yoshida

Publications and source records attributed to Atsushi Yoshida.

At least 37 records · Page 2Linked to original sources

Morphologic evaluation of regenerated small bowel by small intestinal submucosa.

BACKGROUND/PURPOSE: Previous studies have shown small intestinal submucosa (SIS) can be used as biodegradable scaffolds in tissue engineering small intestine. The purpose of this study is to evaluate the regeneration of neointestine and its morphology using SIS. METHODS: A 2-cm tubular SIS graft from Sprague Dawley rat donors was interposed in the middle of a 6-cm ileal Thiry-Vella loop of Lewis rats, which was used to construct an ileostomy. The grafts were harvested at each of the time points ranging from 2 weeks to half a year after implantation, and native small intestine and grafts were investigated for morphology using histology and immunohistochemistry. RESULTS: At the early postoperative period, SIS grafts were colonized by numerous inflammatory cells. A mucosal epithelial layer began to line the luminal surface of the graft by 4 weeks, and by 12 weeks, the luminal surface was covered completely by a layer of neomucosa. Neomucosa with typical small bowel morphology was characterized by a columnar epithelial cell layer with goblet cells, Paneth cells, absorptive enterocytes, and enteroendocrine cells. Significant differences between neomucosa by 12 weeks and 24 weeks in the measurements of mucosal thickness, villus height, and crypt depth were found. The outer walls of SIS grafts were composed of distinct bundles of well-formed smooth muscle-like cells with some fibrovascular tissue. CONCLUSIONS: This initial study suggests that tissue engineering neointestine using SIS can develop structural features of the normal intestine. Small intestinal submucosa might be a viable material in the creation of neointestine for patients suffering short bowel syndrome.

Animals↗

Identification of HIV-1 epitopes that induce the synthesis of a R5 HIV-1 suppression factor by human CD4+ T cells isolated from HIV-1 immunized hu-PBL SCID mice.

We have previously reported that immunization of the severe combined immunodeficiency (SCID) mice reconstituted with human peripheral blood mononuclear cells (PBMC) (hu-PBL-SCID mice) with inactivated human immunodeficiency virus type-1 (HIV-1)-pulsed-autologous dendritic cells (HIV-DC) elicits HIV-1-reactive CD4(+) T cells that produce an as yet to be defined novel soluble factor in vitro with anti-viral properties against CCR5 tropic (R5) HIV-1 infection. These findings led us to perform studies designed to identify the lineage of the cell that synthesizes such a factor in vivo and define the epitopes of HIV-1 protein that have specificity for the induction of such anti-viral factor. Results of our studies show that this property is a function of CD4(+) but not CD8(+) T cells. Human CD4(+) T cells were thus recovered from the HIV-DC-immunized hu-PBL-SCID mice and were re-stimulated in vitro by co-culture for 2 days with autologous adherent PBMC as antigen presenting cells, APC previously pulsed with inactivated HIV in IL-2-containing medium to expand HIV-1-reactive CD4(+) T cells. Aliquots of these re-stimulated CD4(+) T cells were then co-cultured with similar APC's that were previously pulsed with 10 microg/ml of a panel of HIV peptides for an additional 2 days, and their culture supernatants were examined for the production of both the R5 HIV-1 suppression factor and IFN-gamma. The data presented herein show that the HIV-1 primed CD4(+) T cells produced the R5 suppression factor in response to a wide variety of HIV-1 gag, env, pol, nef or vif peptides, depending on the donor of the CD4(+) T cells. Simultaneous production of human interferon (IFN)-gamma was observed in some cases. These results indicate that human CD4(+) T cells in PBMC of HIV-1 naive donors have a wide variety of HIV-1 epitope-specific CD4(+) T cell precursors that are capable of producing the R5 HIV-1 suppression factor upon DC-based vaccination with whole inactivated HIV-1.

Animals↗

Case of mature cystic teratoma of the greater omentum misdiagnosed as ovarian cyst.

The teratoma of the greater omentum is a very rare entity. We present a case of mature cystic teratoma of the greater omentum misdiagnosed as ovarian cyst. The patient was a 36-year-old woman with an omental teratoma of 5 x 4 x 4 cm and an atrophic left ovary. The histopathologic diagnosis was mature cystic teratoma of the greater omentum and no evidence of immaturity or malignancy was noted. Preoperative tumor marker tests revealed moderate elevation of cancer antigen (CA)125, CA19-9 and carcinoembryonic antigen. The left ovary of the patient was atrophic and possible autoamputation of the ovarian tissue might be suggested.

Adult↗

Composition of MRI phantom equivalent to human tissues.

We previously developed two new MRI phantoms (called the CAG phantom and the CAGN phantom), with T1 and T2 relaxation times equivalent to those of any human tissue at 1.5 T. The conductivity of the CAGN phantom is equivalent to that of most types of human tissue in the frequency range of 1 to 130 MHz. In this paper, the relaxation times of human tissues are summarized, and the composition of the corresponding phantoms are provided in table form. The ingredients of these phantoms are carrageenan as the gelling agent, GdCl3 as a T1 modifier, agarose as a T2 modifier, NaCl (CAGN phantom only) as a conductivity modifier, NaN3 as an antiseptic, and distilled water. The phantoms have T1 values of 202-1904 ms and T2 values of 38-423 ms when the concentrations of GdCl3 and agarose are varied from 0-140 micromol/kg, and 0%-1.6%, respectively, and the CAGN phantom has a conductivity of 0.27-1.26 S/m when the NaCl concentration is varied from 0%-0.7%. These phantoms have sufficient strength to replicate a torso without the use of reinforcing agents, and can be cut by a knife into any shape. We anticipate the CAGN phantom to be highly useful and practical for MRI and hyperthermia-related research.

Biomimetic Materials↗

[Clinical calibration dosimetry in JSMP-01: measurements using Farmer-type cylindrical ion chambers.].

The Japan Society of Medical Physics (JSMP) Task Group published Standard dosimetry of absorbed dose in external beam radiotherapy (Standard dosimetry 01) as a new high-energy photon and electron dosimetry protocol in 2002. In this study, we present Standard dosimetry 01 as the JSMP-01 protocol for the convenience of users. This protocol is based on using an ion chamber having a (60)Co absorbed dose to water calibration coefficient, N(D,w), which is calculated from a (60)Co exposure calibration coefficient, N(c). We present dose comparisons between a reference chamber and various Farmer-type cylindrical chambers with different wall materials. The absorbed dose to water was compared at the calibration depths of 5 cm for a (60)Co beam, 10 cm for photons, and d(c) = 0.6 R(50) - 0.1 (cm) for electrons according to JSMP-01. The JARP chamber in the Kyushu Regional Center which meets third-order standards in Japan was used as the reference chamber. The absorbed dose to water for the Farmer-type chambers determined according to JSMP-01 agreed with that for the JARP chamber within 1% for photon and electron beams. The doses obtained by JSMP-01 and the Japan Association of Radiological Physics protocol (JARP-86) were also compared for photon and electron beams. For the Farmer-type chambers with photon beams, JSMP-01 results were up to 1.5% higher than JARP-86 results. For electron beams JSMP-01 results were higher than JARP-86 results by 1.3-2.8%.

Calibration↗

[Clinical calibration dosimetry in JSMP-01: measurements using plane-parallel ion chambers.].

The Japan Society of Medical Physics (JSMP) Task Group published Standard dosimetry of absorbed dose in external beam radiotherapy (Standard dosimetry 01) as a new high-energy photon and electron dosimetry protocol in 2002. In this study, we present Standard dosimetry 01 as the JSMP-01 protocol for the convenience of users. This protocol is based on using an ion chamber having a (60)Co absorbed dose to water calibration coefficient, N(D,w), which is calculated from a (60)Co exposure calibration coefficient, N(c). We present dose comparisons between a reference chamber and various plane-parallel chambers. The absorbed dose to water was compared at the calibration depth of 5 cm for a (60)Co beam and d(c) = 0.6R(50) - 0.1 (cm) for electron beams according to JSMP-01. The absorbed dose to water calibration coefficients, [N(D,w)](Co) and [N(D,w)](18E), for the plane-parallel chambers were also determined by (60)Co and electron beam cross-calibrations using a reference chamber. The dose for the plane-parallel chambers derived from [N(D,w)](Co) and [N(D,w)](18E) was compared to that for the reference chamber using electron beams. The JARP chamber in the Kyushu Regional Center which meets third-order standards in Japan was used as the reference chamber. The doses for the plane-parallel chambers determined according to JSMP-01 agreed with that for the JARP chamber within 1% and 2% for (60)Co and electron beams, respectively. For electron beams, the doses for the plane-parallel chambers calculated from [N(D,w)](Co) and [N(D,w)](18E) were within 1.5% and 1.0% compared to those for the JARP chamber, respectively, except for the Exradin A10 chamber.

Calibration↗

Quantitative analysis of tooth pulp afferent terminals in the rat brain stem.

This study analyzed quantitatively the ultrastructural features of tooth pulp afferent terminals and their presynaptic axonal endings (p-endings) in the trigeminal principal (Vp), dorsomedial oral (Vdm), and caudal nuclei (Vc). Mitochondrial volume, active zone area, apposed surface area, and vesicle number were highly correlated with afferent bouton volume. The afferent bouton volume varied widely in Vp, compared to that in Vdm and Vc. The values of all parameters of p-endings were within a narrow range, and were smaller than those of afferent boutons. The afferent bouton volume correlated with the number of postsynaptic dendrites and p-endings. These results suggest that pulpal afferent information is regulated in a unique manner in the each trigeminal sensory nucleus.

Afferent Pathways↗

Different corticostriatal projections from two parts of the cortical masticatory area in the rabbit.

The cortical masticatory area (CMA) elicits rhythmic jaw movements in response to repetitive stimulation and is involved in the control of mastication. Based on jaw movement patterns, the CMA is divided into two parts. One is the part of the CMA in which a T-pattern similar to jaw movements during food transport in natural mastication is evoked by electrical stimulation. The other is more dorsomedially located, and during chewing a C-pattern similar to jaw movements can be induced. However, it is still not known which region of the putamen receives projections from the CMA and whether projections originate from both parts of the CMA. In this study, electrophysiological and histological experiments were undertaken in rabbits to investigate projections from the CMA to the putamen. Both experiments showed that the ventral region of the putamen received projections from the CMA. The density of the projections from the CMA area inducing the T-pattern seemed to be higher than that from the area inducing the C-pattern. Furthermore, the peak latency of the evoked potentials from stimulation of the CMA area inducing the T-pattern was shorter than that from stimulation of the area inducing the C-pattern. The data obtained from the present study indicate the functional role of the ventral region of the putamen in the regulation of mastication, and further suggest that the corticostriatal pathway is involved in the transition between behavioral jaw movement patterns.

Animals↗

Plasmid encoding interleukin-4 in the amelioration of murine collagen-induced arthritis.

OBJECTIVE: To evaluate the therapeutic effect of the administration of plasmid encoding interleukin-4 (IL-4) via gene-gun delivery and via intradermal injection on collagen-induced arthritis (CIA). METHODS: IL-4 plasmid was administered by gene-gun delivery and intradermal injection to DBA/1 mice immunized with type II collagen (CII). The therapeutic effect on the development of CIA was evaluated clinically with a visual scoring method for arthritis and serologically by enzyme-linked immunosorbent assays and polymerase chain reaction. RESULTS: Treatment with IL-4-expressing plasmid significantly reduced the incidence and severity of CIA, including a reduction in the anti-CII antibody level. In particular, gene-gun delivery had a higher immunosuppressive effect on CIA compared with intradermal injection. As shown by in vitro stimulation assay, the spleen cells from mice immunized with CII and treated with IL-4 plasmid via gene gun exhibited higher Th2 cytokine responses compared with cells treated with control plasmid after in vitro stimulation with CII. CONCLUSION: The results of this study suggest that treatment with IL-4 plasmid may constitute a new clinical use of cytokine gene therapy for rheumatoid arthritis.

Animals↗

Video-assisted thoracic surgery lobectomy for extralobar pulmonary sequestration in a child: report of a case.

Pulmonary sequestration in infants and children is conventionally treated by resecting the sequestered lung parenchyma (sequestrectomy) or by performing lobectomy through a standard thoracotomy. We performed lobectomy by video-assisted thoracic surgery, using an original tracheal tube that we designed, in a 6-year-old boy with extralobar pulmonary sequestration and bronchiectasis in the left lower lobe.

Bronchopulmonary Sequestration↗

Histamine production via mast cell-independent induction of histidine decarboxylase in response to lipopolysaccharide and interleukin-1.

Histamine modulates immune responses. There are at least two ways histamine might be supplied: one is its release from cells that pool pre-formed histamine and the other is its de novo formation via induction of histidine decarboxylase (HDC). Lipopolysaccharide (LPS) and the proinflammatory cytokine interleukin (IL)-1 induce a marked elevation of HDC activity in various tissues or organs. To examine the contribution of mast cells to HDC induction in mice given LPS or IL-1, we examined the effects of LPS and IL-1 on HDC activity and/or histamine content in various organs (liver, lung, spleen or bone marrow) in mast cell-deficient mice (W/Wv), their normal littermates (+/+) and BALB/c mice deficient in IL-1alpha, IL-1beta and tumor necrosis factor (TNF)-alpha (IL-1alpha beta/TNFalphaKO mice). In non-stimulated mice, the histamine in the lung and spleen was contained largely within mast cells. The LPS-stimulated increase in HDC activity in a given organ was similar between +/+ and W/W(v) mice, and between IL-1alpha beta/TNFalphaKO BALB/c and control BALB/c mice, and led to increases in histamine. In W/Wv and +/+ mice, IL-1alpha also elevated HDC activity. These results suggest that (i) in liver, lung and spleen, either the major cells supplying histamine via HDC induction in response to LPS and IL-1 are not mast cells, or mast cells are not a prerequisite for the induction of HDC; (ii) the cells in which HDC is induced by LPS and IL-1 are similar or identical in a given organ; and (iii) neither IL-1 nor TNF-alpha is a prerequisite for the induction of HDC by LPS.

Animals↗

Comparison of patients with Behçet's disease in the 1980s and 1990s.

OBJECTIVE: To compare clinical findings in patients with Behçet's disease (BD) seen in 2 different decades (1980s and 1990s) to determine if there has been a shift toward the appearance of less severe disease. DESIGN: Retrospective, comparative case series. PARTICIPANTS: Two hundred forty patients with uveitis caused by BD who had their first visit and at least a 4-month follow-up at the uveitis clinic of University of Tokyo Hospital between January 1980 and December 1999 were enrolled. METHODS: Patients were divided into 2 groups according to the date of the first visit. The clinical profiles were then compared between the 1980s group (133 patients, observed for 33.5+/-26.4 months) and the 1990s group (107 patients, observed for 46.9+/-32.6 months). MAIN OUTCOME MEASURES: Number of ocular attacks per year, visual outcomes, and the percentage of patients who had cyclosporine or cyclophosphamide therapy. RESULTS: Age of onset, type of inflammation, incidence of secondary glaucoma, and surgical history of glaucoma and cataract did not differ between the 1980s and the 1990s. Conversely, in patients in the 1990s, the number of ocular attacks per year and the percentage of patients with cyclosporine or cyclophosphamide therapy decreased significantly. Furthermore, the percentage of eyes with good visual acuity (VA) (?20/30) increased, and the percentage of eyes with poor VA (<20/200) decreased significantly at both the first and the last examinations. There was a trend for less bilateral disease and fewer genital ulcers in the 1990s as well. CONCLUSIONS: Through a study of Japanese patients, we confirmed that the clinical outcomes of BD, especially judging by the number of ocular attacks per year and VA, indeed improved during the 1990s.

Adolescent↗

The efficacy and limitations of sirolimus conversion in liver transplant patients who develop renal dysfunction on calcineurin inhibitors.

This study evaluates sirolimus in preserving renal function in 28 patients who developed renal insufficiency after liver transplantation. Patients with a creatinine level higher than 1.8 mg/ml were eligible for conversion. Of the 28 patients, 7 (25%) did not tolerate sirolimus, 6 (21%) progressed to end-stage renal disease (ESRD), and 14 (50%) have been maintained on sirolimus with stable renal function. The 28 patients overall had a decline in creatinine of 0.38 mg/dl (P = 0.029) at week 4, with a small increase by week 24. However, the subset of 14 patients who did not develop ESRD had a decline in creatinine that persisted to week 48. While the differences between those who developed ESRD and those with stable renal function were not statistically significant, the patients who developed ESRD had a higher creatinine at conversion (2.8 vs 2.3) and a lower creatinine clearance (36 vs 53 ml/min). Patients receiving sirolimus had a persistent rise in cholesterol (P < 0.05). The use of sirolimus to preserve renal function was limited by patients unable to tolerate drug- (25%) and patients who developed ESRD (21%). A subgroup of patients (50%) had an improvement in creatinine that persisted for 48 weeks.

Calcineurin↗

Viral load of human herpesvirus 8 (HHV-8) in the circulatory blood cells correlates with clinical progression in a patient with HHV-8-associated solid lymphoma with aids-associated Kaposi's sarcoma.

We encountered a case of a rapidly progressive HHV-8-associated solid lymphoma with AIDS-associated Kaposi's sarcoma (KS). HHV-8 DNA load in whole blood cells was analyzed quantitatively by real-time PCR using amplification of the HHV-8-encoded ORF26 gene. Ours is the first observation that the rapid increase in the HHV-8 viral load (from 1.9x10(4) copies/microg to 1.6x10(6) copies/microg in 40 days) in conjunction with low CD4+ cell counts was accompanied by an accelerated clinical disease progression. The results indicate that the quantity of circulating HHV-8 is measurable with real-time PCR and can provide clinically useful information.

AIDS-Related Opportunistic Infections↗

Rapid progression of native renal artery fibromuscular dysplasia following kidney donation.

Fibromuscular dysplasia is the second commonest anatomical abnormality apart from multiple renal arteries in the potential live donors. Pretransplant evaluation of the donors may include an angiography to evaluate the renal arteries, and failure to recognize renal arterial stenosis, particularly fibromuscular dysplasia, by noninvasive methods may eventually lead to hypertension and ischemic renal failure. We report a case of fibromuscular dysplasia that was undetected by computed tomographic angiography prior to donation. One year after kidney donation, it rapidly progressed to severe symptomatic stenosis with hypertension and acute renal failure. Following renal artery angioplasty, her blood pressure normalized over a period of 2 weeks without any need for antihypertensive medications and the serum creatinine returned to her baseline. The acceptability of renal donors with fibromuscular dysplasia depends on the age, race and the availability of the other suitable donors. Mild fibromuscular dysplasia in a normotensive potential renal donor cannot be considered a benign condition. Such donors need regular follow-up postdonation for timely detection and treatment.

Adult↗

Neuroblastoma detected by mass screening: the Tumor Board's role in its treatment.

Japan has a nationwide mass-screening program for neuroblastoma in 6-month-old infants. Neuroblastoma can regress spontaneously, and some institutions observe selected cases. We evaluated the management of screened neuroblastoma at our hospital since 1997 when an observation program was introduced. Criteria for the observation program were stage-I, stage-II, or stage-IVs tumors, urinary vanillylmandelic acid (VMA) and homovanillic acid (HVA) levels <40 microg/mg creatinine, tumor <5 cm in diameter, no invasion to the intraspinal canal or great vessels, and parental consent to participate. Patients who did not meet observation criteria underwent surgery or mild chemotherapy according to the location of the tumor. If patients met observation criteria after chemotherapy, surgical intervention was no longer performed. Thirty-six patients attended our hospital for screened neuroblastoma from 1997 to 2002. Thirty-three patients who were managed at our hospital participated in this study. Ten subjects met observation criteria. Tumors regressed in 7 patients (mean follow-up period 36.3 months) with corresponding decreases in VMA and HVA levels (group A). Three underwent surgery (group B) because of increasing VMA and HVA levels, increase in tumor size, or guardian's request. Twenty-three subjects did not meet observation criteria. Four patients underwent primary surgery (group C), and 19 patients had chemotherapy initially. Fourteen patients met observation criteria after chemotherapy and two are still having chemotherapy (group D). Three patients required surgery due to insufficient regression of their tumors (group E). Fourteen subjects in group D had marked decreases in VMA and HVA levels and tumor size (mean follow-up period 29.1 months), and tumors were not detected using imaging techniques in 8 patients. Histological examination of all resected specimens during the study period showed favorable histology and no N-myc amplification. There was no evidence of unfavorable prognosis in any of the 33 subjects, although 1 patient who underwent primary surgery had a vanishing kidney 1 year later and 1 patient had multiple bony metastases after complete resection of tumor, which was treated by chemotherapy. Until the real significance of mass screening for neuroblastoma as a public health measure is confirmed, observation with careful follow-up should be adopted more extensively because it has a favorable outcome in many cases, and is associated with minimal therapeutic complications.

Adrenal Gland Neoplasms↗

Effects of a new dexamethasone-delivery system (Surodex) on experimental intraocular inflammation models.

BACKGROUND: To investigate the effects of a new biodegradable dexamethasone drug delivery system, Surodex, in two experimental intraocular inflammation models; endotoxin-induced uveitis (EIU) and experimental autoimmune uveoretinitis (EAU). METHODS: Surodex was inserted into the right anterior chambers (ACs) of rats. In the EIU experiment, protein concentration, cell infiltration, and myeloperoxidase (MPO) activity in the aqueous humor were measured 24 h after injection. Eyes were evaluated histopathologically. In the EAU experiment, firstly, Surodex was administered at various days after immunization. Then, Surodex was administered on day 9 and eyes were evaluated histopathologically. Intraocular cytokine levels (IFN-gamma and IL-4) were investigated. RESULTS: In the EIU experiments, eyes with Surodex exhibited significantly reduced inflammation compared with contralateral controls. Protein concentrations, cell infiltrations, as well as MPO activity were reduced. In the EAU experiments, all rats with Surodex given on days 0 or 7 showed no or significantly reduced inflammation in both eyes. Rats treated on day 12 developed reduced inflammation only in the treated eyes. IFN-gamma levels were significantly lower in the eyes with Surodex, whereas IL-4 was not detectable. CONCLUSIONS: This new, biodegradable corticosteroid drug-delivery system is highly effective in suppressing intraocular inflammation, and should be a useful tool to manage uveitis in humans.

Animals↗