Biomedical subjects

K Imaoka

Publications and source records attributed to K Imaoka.

At least 19 recordsLinked to original sources

PubMed2005

Examination of quantitative and fractal analysis of sway characteristics of the center of foot pressure movement during a static upright posture. Analysis based on alcohol intake.

AIM: This study aimed to examine the sway characteristics of center of foot pressure (CFP) movement during a static upright posture under the influence of alcohol by using quantitative and fractal analysis. METHODS: Eleven healthy young people participated. They drank in a range of 0.54-1.83 ml/kg of alcohol, standardized by body mass, within 10 min. Blood pressure, heart rate, 2 types of nervous function tests and the CFP movement were measured before and after the alcohol intake. Thirty-six parameters of the CFP movement were used for quantitative analysis. Diffusion coefficient, scaling exponent and critical point coordinates were used in fractal analysis. RESULTS: Quantitative analysis confirmed that the CFP parameters such as distance, velocity and area were significantly changed, although the parameters evaluating cyclical characteristics and center average were not. Fractal analysis confirmed that critical point coordinates existed at time-lag=1.0 before and after the alcohol intake, and the short-term region (ST) and long-term region (LT) could be separated. A diffusion coefficient in the ST was larger than that in the LT, and the scaling exponent was over 0.5 in the ST and under 0.5 in the LT. CONCLUSIONS: Influences of alcohol intake were found in amount of body-sway, but not in the displacement or periodicity of the CFP parameters. Fractal analysis confirmed that CFP movement was dependent on time-series, and its characteristics changed before and after the time-series critical point and was unsteady.

Adolescent↗

PubMed2002

Dorsal skin responses to subchronic ultraviolet B (UVB)-irradiation in Wistar-derived hypotrichotic WBN/ILA-Ht rats.

Dorsal skin responses to a subchronic UVB-irradiation (10kJ/m2/rat /day), were examined in Wistar-derived hypotrichotic WBN/ILA-Ht rats for up to 3 months. Hyperplasia of epidermal cells and hair follicle epithelial cells as well as parakeratosis developed at 1 month and progressed thereafter, resulting in a prominent epidermis thickening and formation of epidermal ingrowths projecting into the dermis. At the same time, the percentage of proliferating cell nuclear antigen (PCNA)-positive epidermal cells significantly increased after I month. In some portions of the hyperplastic epidermis, especially of the epidermal ingrowths, keratinocytes were somewhat pleomorphic and migrated into the dermis. In the upper dermis, edema with capillary congestion, mast cell infiltration and fibroblast proliferation developed at I month, and the intensity of edema and the number of dermal mast cells was most prominent at 3 months. Edema spread to the epidermis, resulting in intercellular edema and subsequent dissociation of epidermal cells. Degeneration of collagen fibers was also detected in the upper dermis, especially beneath the epidermis. In addition, although not significant because of a large individual difference, the serum IgE concentration, showed a tendency to increase after 2 months. The present study clarified the characteristics of the dorsal skin responses to a subchronic UVB-irradiation in rats.

Animals↗

PubMed2000

Enterotoxin adjuvants have direct effects on T cells and antigen-presenting cells that result in either interleukin-4-dependent or -independent immune responses.

In an in vitro study, Escherichia coli heat-labile toxin (LT) was shown to directly affect activated CD4(+) T cells and support interleukin (IL)-5 production in IL-4-deficient (IL-4(-/-)) mice, whereas cholera toxin (CT) did not. Both LT and CT enhanced B7-2 expression on B cells and macrophages. These effects were not influenced by CD40-CD40 ligand cosignaling. Addition of LT- or CT-treated antigen-presenting cells to anti-CD3-triggered CD4(+) T cells resulted in the induction of T cell proliferative responses. Further, these responses were inhibited by anti-B7-2 monoclonal antibody. Cocultivation of CD4(+) T cells with LT- or CT-treated antigen-presenting cells and anti-CD3 enhanced Th1- and IL-4-mediated Th2-type cytokine production. The results from in vitro studies were supported by in vivo studies in IL-4(-/-) mice, in which LT induced mucosal IgA responses but CT did not. Thus, although both LT and CT induce mucosal adjuvant responses via IL-4-dependent Th2-type responses, LT also elicits Th1- and IL-4-independent Th2-type responses.

Animals↗

PubMed1999

Leukoencephalopathy with cerebral amyloid angiopathy: a semiquantitative and morphometric study.

To investigate changes in caliber of vessels in leukoencephalopathy with cerebral amyloid angiopathy (CAA) we performed a histological and morphometric study of cerebral arteries in this disease. We histologically examined changes in cortico-leptomeningeal arteries in five cases of leukoencephalopathy with CAA and compared their morphometrically determined wall-to-lumen ratio [(external diameter-internal diameter) x 0.5/internal diameter] with those of amyloid-negative arteries to estimate stenotic changes. Additionally, we compared wall-to-lumen ratios of medullary arteries in brains with CAA and white matter lesions (WML) (CAA(+)/WML(+), n = 5), subcortical arteriosclerotic encephalopathy without CAA (CAA(-)/WML(+), n = 7), and neither CAA nor white matter lesions (CAA(-)/WML(-), n = 5). Amyloid-positive arteries had thinned walls and dilated lumens. The external diameter and the wall-to-lumen ratio for amyloid-positive arteries was smaller than for amyloid-negative arteries in CAA(+)/WML(+) brains. There was no significant difference in the external diameters among the three groups. The wall-to-lumen ratio for medullary arteries in CAA(-)/WML(+) brains was significantly greater than for CAA(+)/WML(+) and CAA(-)/WML(-), but there was no significant difference between CAA(+)/WML(+) and CAA(-)/WML(-). Amyloid deposition causes degeneration of the tunica media, resulting in thinning of the wall and dilation of the lumen. The tunica media of small arteries is important in regulation of cerebral blood flow with degeneration causing impairment of cerebrovascular autoregulation in response to blood pressure. This impairment may lead to white matter lesions.

Aged↗

PubMed1999

Mucosal Th1- versus Th2-type responses for antibody- or cell-mediated immunity to simian immunodeficiency virus in rhesus macaques.

Simian immunodeficiency virus (SIV)-specific B cell responses and the Th1- or Th2-type profiles of cytokine expression were determined for rhesus macaques immunized with SIV antigens via the iliac lymph nodes (by use of a targeted lymph node [TLN] procedure) or orally with SIV p55gag plus cholera toxin (CT) as a mucosal adjuvant. Analysis of CD4+ T cells purified from SIV-stimulated peripheral blood mononuclear cells of immunized macaques revealed that Th2 cytokine production gradually increased after the second and third TLN immunization. Analysis of SIV-specific B cell responses revealed that peak SIV-specific IgA B cell responses followed the third TLN immunization and occurred during peak Th2-type T cell responses. Oral immunization of macaques with p55gag plus CT induced interferon-gamma-secreting Th1-type and select Th2-type cytokine-producing CD4+ T helper cells, which most likely accounted for the induction of p55-specific systemic IgG and mucosal IgA responses.

Animals↗

PubMed1998

Nasal immunization of nonhuman primates with simian immunodeficiency virus p55gag and cholera toxin adjuvant induces Th1/Th2 help for virus-specific immune responses in reproductive tissues.

Female rhesus macaques were nasally immunized with p55gag (p55) of SIV and cholera toxin as a mucosal adjuvant. Nasal immunization induced Ag-specific IgA and IgG Abs in mucosal secretions (e.g., cervicovaginal secretions, rectal washes, and saliva) and serum. Furthermore, high numbers of p55-specific IgA and IgG Ab-forming cells were induced in mucosal effector sites, i.e., uterine cervix, intestinal lamina propria, and nasal passage. p55-specific CD4+ T cells in both systemic and mucosal compartments expressed IFN-gamma and IL-2 (Th1-type)- as well as IL-5, IL-6, and IL-10 (Th2-type)-specific mRNA. Moreover, p55-specific CTL activity was demonstrated in lymphocytes from blood, tonsils, and other lymphoid tissues. These results show that nasal immunization with SIV p55 with cholera toxin elicits both Th1- and selective Th2-type cytokine responses associated with the induction of SIV-specific mucosal and serum Abs, and CTL activity. These results offer a promise for the development of protective mucosal immunity to SIV.

Adjuvants, Immunologic↗

PubMed1998

No mutations in cystatin C gene in cerebral amyloid angiopathy with cystatin C deposition.

To investigate the relationship between cerebral amyloid angiopathy (CAA) and cystatin C, we studied five CAA patients on whose cerebral blood vessels colocalization of cystatin C and beta-protein was recognized immunohistochemically. One patient was suspected as familial CAA and the other patients were sporadic cases. Two patients had low concentration of cystatin C in their cerebrospinal fluid (CSF) as we have previously reported in CAA patients. Enzyme-linked immunosorbent assay (ELISA) revealed that cystatin C and beta-protein have been included at the ratio of about 1:100 in the crude amyloid fibrils of one patient. Using a monoclonal antibody (MAb) against cystatin C, we performed affinity chromatography and immunoblotting on her amyloid fibril fraction. Eluate showed a band with a mol wt of 14,000 and the N-terminal 14 amino acid residues of 14-kDa protein were identical with that of cystatin C. This molecular weight is not identical to that of the truncated form of cystatin C deposited in hereditary cerebral hemorrhage with amyloidosis in Iceland (HCHWA-I), but that of normal cystatin C. DNA sequence analysis of five patients showed no point mutations in the cystatin C gene. Cystatin C and beta-protein colocalization, which was recognized in amyloid lesions of CAA, suggests that cystatin C deposition may be related to beta-protein deposition. We hypothesize that cystatin C deposition in sporadic cerebral amyloid angiopathy with cystatin C deposition (SCCAA) involves a different mechanism from that in HCHWA-I, which may be related to low CSF concentration of cystatin C without amino acid substitutions.

Aged↗

PubMed1998

Induction of Th2 cytokine expression for p27-specific IgA B cell responses after targeted lymph node immunization with simian immunodeficiency virus antigens in rhesus macaques.

To determine if there is an association between the isotype of simian immunodeficiency virus (SIV)-specific B cell responses and the profile of Th1 and Th2 cytokine expression, rhesus macaques were immunized with SIV antigens via the iliac lymph nodes, using a targeted lymph node (TLN) immunization procedure. When CD4+ T cells purified from antigen-stimulated peripheral blood mononuclear cells were analyzed, the levels of Th2 cytokine production were gradually increased after the second and third immunizations. However, interferon-gamma production did not change. Analysis of SIV-specific B cell responses revealed that the main isotype was IgG after the second and third immunizations. In addition, a peak of SIV-specific IgA B cell responses was noted following the third immunization. These findings suggest that the induction of Th2 type responses in TLN-immunized rhesus macaques reflects the sequence of initial induction of SIV-specific IgG-producing cells followed by IgA-secreting cells.

Animals↗

PubMed1998

Presence of anti-ovalbumin IgE antibody in the sera of laboratory-reared squirrel monkeys (Saimiri sciureus) fed quail eggs.

In this study, we examined serum anti-ovalbumin (OVA) IgE and IgG antibodies in laboratory-reared squirrel monkeys (Saimiri sciureus), that were fed a boiled quail egg everyday. We found that 36 of 95 monkeys (38%) possessed specific IgE and 44% (42/95) had specific IgG against OVA. These antibody titers seemed to increase with age. There was, however, no apparent correlation between the anti-OVA IgE and IgG antibody titers.

Animals↗

PubMed1998

[A case of hereditary motor and sensory neuropathy with pyramidal tract sign, optic nerve atrophy and mental retardation].

The patient was a 61-year-old man who suffered from gait disturbance since childhood. He also had mental retardation. Gait disturbance was slowly progressive. His mother, sister, brother and son of his sister suffered from gait disturbance. On neurological examination, he showed mental retardation, optic nerve atrophy and neural deafness. He also showed severe muscle atrophy and weakness of bilateral lower limbs associated with pes cavus. Muscle tonus of lower limbs and patellar tendon reflex were increased bilaterally. Achilles tendon reflex was absent. Babinski and Chaddock signs were positive. Superficial and deep sensations were almost normal. There were no cerebellar signs. Blood chemistry was normal. On nerve conduction studies, motor nerve conduction velocity of the upper limbs was normal and that of the posterior tibial nerve was decreased; right 36.0m/sec, left 29.7m/sec. Sensory nerve conduction velocity of the median nerve was slightly decreased; right 36.5m/sec, left 45.2m/sec and sural nerve did not respond to electric stimuli. On sural nerve biopsy, the density of myelinated fibers was severely decreased. Onion bulb formation was not observed. We classified this case as hereditary motor and sensory neuropathy (HMSN) type II based on nerve conduction studies and findings from sural nerve biopsy. HMSN with pyramidal tract sign has been classified as type V and HMSN with optic nerve atrophy as type VI. This case had characteristic symptoms as type V and VI. Histopathological findings of HMSN type V and VI have not been established yet. This case might provide an important clue for classification of HMSN.

Hereditary Sensory and Motor Neuropathy↗

PubMed1997

Oral immunization with simian immunodeficiency virus p55gag and cholera toxin elicits both mucosal IgA and systemic IgG immune responses in nonhuman primates.

Rhesus macaques were orally immunized with a mucosal vaccine consisting of two different concentrations (1 mg vs 250 microg) of recombinant SIV p55gag (p55) with or without cholera toxin (CT, 50 microg) as a mucosal adjuvant. The plasma from macaques receiving the higher dose of p55 (1 mg) and CT had higher p55-specific IgG and IgA Ab titers compared with macaques that received the lower dose of p55 (250 microg) and CT. Further, high levels of p55-specific IgG and IgA Abs were present in external secretions from both groups. The level of p55-induced T cell responses was elevated in PBMCs isolated from the high dose group compared with the low dose group. When culture supernatants from these p55-stimulated PBMCs were examined for Th1 (IFN-gamma) and Th2 (IL-4 and IL-10) cytokines, both IFN-gamma and IL-10 were present, but IL-4 was absent. CD4+ T cells isolated from these p55-stimulated PBMCs contained IFN-gamma spot-forming cells (SFCs) but not IL-4 SFCs. These results were further confirmed by cytokine-specific reverse transcriptase PCR analysis, where p55-specific CD4+ T cells expressed mRNA for IFN-gamma, IL-6, and IL-10, but not IL-4. These findings suggest that oral immunization of nonhuman primates induced both IFN-gamma-secreting Th1 and select Th2 cytokine (e.g., IL-6 and IL-10)-producing CD4+ Th cells, which accounted for the generation of p55-specific systemic and mucosal Ab responses.

Administration, Oral↗

PubMed1997

A nontoxic mutant of cholera toxin elicits Th2-type responses for enhanced mucosal immunity.

We have characterized a nontoxic mutant of cholera toxin (CT) as a mucosal adjuvant in mice. The mutant CT was made by substitution of serine with phenylalanine at position 61 of the A subunit (S61F), which resulted in loss of ADP ribosyltransferase activity and toxicity. Mice were intranasally immunized with ovalbumin, tetanus toxoid, or influenza virus either alone or together with mutant CT S61F, native CT, or recombinant CT-B. Mice immunized with these proteins plus S61F showed high serum titers of protein-specific IgG and IgA antibodies that were comparable to those induced by native CT. Further, high protein-specific IgA antibody responses were observed in nasal and vaginal washes, saliva, and fecal extracts as well as increased numbers of IgG and IgA antibody forming cells in cervical lymph nodes and lung tissues of mice intranasally immunized with these proteins and S61F or native CT, but not with recombinant CT-B or protein alone. Both S61F and native CT enhanced the induction of ovalbumin-specific CD4(+) T cells in lung and splenic tissues, and these T cells produced a Th2-type cytokine pattern of interleukin 4 (IL-4), IL-5, IL-6, and IL-10 as determined by analysis of secreted proteins and by quantitation of cytokine-specific mRNA. These results have shown that mutant CT S61F is an effective mucosal adjuvant when administrated intranasally and induces mucosal and systemic antibody responses which are mediated by CD4(+) Th2-type cells.

Animals↗

PubMed1997

Mutants in the ADP-ribosyltransferase cleft of cholera toxin lack diarrheagenicity but retain adjuvanticity.

Cholera toxin (CT), the most commonly used mucosal adjuvant in experimental animals, is unsuitable for humans because of potent diarrhea-inducing properties. We have constructed two CT-A subunit mutants, e.g., serine-->phenylalanine at position 61 (S61F), and glutamic acid-->lysine at 112 (E112K) by site-directed mutagenesis. Neither mutant CT (mCT), in contrast to native CT (nCT), induced adenosine diphosphate-ribosylation, cyclic adenosine monophosphate formation, or fluid accumulation in ligated mouse ileal loops. Both mCTs retained adjuvant properties, since mice given ovalbumin (OVA) subcutaneously with mCTs or nCT, but not OVA alone developed high-titered serum anti-OVA immunoglobulin G (IgG) antibodies (Abs) which were largely of IgG1 and IgG2b subclasses. Although nCT induced brisk IgE Ab responses, both mCTs elicited lower anti-OVA IgE Abs. OVA-specific CD4+ T cells were induced by nCT and by mCTs, and quantitative analysis of secreted cytokines and mRNA revealed a T helper cell 2 (Th2)-type response. These results now show that the toxic properties of CT can be separated from adjuvanticity, and the mCTs induce Ab responses via a Th2 cell pathway.

Adjuvants, Immunologic↗

PubMed1997

Progressive supranuclear palsy with palatal myoclonus.

We present a case of progressive supranuclear palsy (PSP) with palatal myoclonus occurred in a 64-year-old man. The nucleus olivaris of the medulla oblongata showed high signal intensity on T2-weighted MR images, indicating brainstem tegmental atrophy, which were confirmed as hypertrophy of the nucleus inferior olivaris at autopsy. The characteristic neuropathological findings were marked grumose degeneration of the dentate nucleus, degeneration and gliosis of the superior cerebellar peduncle, and hypertrophy of the bilateral olivary nuclei. As far as we know, although a few cases of PSP with olivary hypertrophy have been described, only one case has presented with palatal myoclonus.

Cerebellum↗

PubMed1997

Diesel exhaust particles enhance antigen-induced airway inflammation and local cytokine expression in mice.

Previous experimental studies have suggested that nasal instillation of diesel exhaust particles (DEP) can enhance nasal IgE response and cytokine production. However, there is no experimental evidence for the relation of DEP to allergic asthma. We investigated the effects of DEP inoculated intratracheally on antigen-induced airway inflammation, local expression of cytokine proteins, and antigen-specific immunoglobulin production in mice. DEP aggravated ovalbumin-induced airway inflammation characterized by infiltration of eosinophils and lymphocytes and an increase in goblet cells in bronchial epithelium. DEP with antigen markedly increased interleukin-5 (IL-5) protein levels in lung tissue and bronchoalveolar lavage supernatants compared with either antigen or DEP alone. The combination of DEP and antigen induced significant increases in local expression of IL-4, granulocyte macrophage-colony stimulating factor (GM-CSF), and IL-2, whereas expression of interferon-gamma was not affected. In addition, DEP exhibited adjuvant activity for the antigen-specific production of IgG and IgE. These results provide the first experimental evidence that DEP can enhance the manifestations of allergic asthma. The enhancement may be mediated mainly by the increased local expression of IL-5, and also by the modulated expression of IL-4, GM-CSF, and IL-2.

Animals↗

PubMed1997

Functional gamma delta T-lymphocyte defect associated with human immunodeficiency virus infections.

BACKGROUND: Antiviral cellular immune responses may influence immunological homeostasis in HIV-infected persons. Recent data indicate that V gamma 9/V delta 2 T lymphocytes display potent cytotoxic activities against human cells infected with certain viruses including HIV. Understanding the role of gamma delta T cells in the course of HIV infection may be helpful for designing novel treatment strategies for HIV-associated disorders. MATERIALS AND METHODS: The constitutive recognition of Daudi cells and monoethyl pyrophosphate (Etpp) by peripheral blood V gamma 9/V delta 2 T cells was assessed using a proliferation assay. The cytotoxicity of Daudi-stimulated lymphocyte populations was measured by chromium release assays. The HIV infectivity for gamma delta T cell clones was determined by measuring the levels of HIV p24 in cell supernatants. The effect of in vitro HIV-infection on cytokine mRNA production by gamma delta T cell clones was assessed by PCR. RESULTS: The constitutive proliferative responses of peripheral blood V gamma 9/V delta 2 T cells and the lytic functions of Daudi-expanded lymphoid cells from HIV+ persons were substantially diminished in comparison with those of HIV-seronegative persons. These alterations were present in asymptomatic HIV+ persons prior to substantial alpha beta CD4+ T cell loss. Productive HIV infection of gamma delta T cells in vitro had no measurable effect either on their proliferative response to Daudi stimuli or on the expression of cytokine mRNAs for IFN-gamma, IL-2, IL-4, IL-5, IL-6, IL-10, and IL-13. CONCLUSIONS: The constitutive responsiveness of V gamma 9/V delta 2 T lymphocytes to Daudi and Etpp is severely altered in HIV+ persons. HIV infection of gamma delta T cells in vitro does not substantially change their cytokine expression or antigenic response.

Cell Division↗

PubMed1996

Leukoencephalopathy-related cerebral amyloid angiopathy with cystatin C deposition.

BACKGROUND: We have described sporadic cases of cerebral amyloid angiopathy with cerebral hemorrhage showing a low cystatin C level in the cerebrospinal fluid detected by enzyme-linked immunosorbent assay. Recently, several cases of leukoencephalopathy in patients with cerebral amyloid angiopathy have been reported. We describe a sporadic case of leukoencephalopathy with cystatin C-type cerebral amyloid angiopathy diagnosed during life by enzyme-linked immunosorbent assay. CASE DESCRIPTION: A 74-year-old man who had suffered from progressive dementia for 3 years was admitted with right hemiparesis, dysarthria, and ataxia. MRI revealed pontine infarction and multiple lacunar state with leukoaraiosis. We suspected cystatin C-type cerebral amyloid angiopathy because of the low level of cystatin C in the cerebrospinal fluid. The patient died of sepsis 3 months later, and the presence of leukoencephalopathy with cerebral amyloid angiopathy was confirmed by autopsy. Immunohistological examination disclosed cystatin C and beta-protein deposition in amyloid structures of the cortical cerebral arteries. CONCLUSIONS: Measurement of cystatin C in the cerebrospinal fluid by enzyme-linked immunosorbent assay is a useful method of diagnosing leukoencephalopathy related to sporadic cystatin C-type cerebral amyloid angiopathy.

Aged↗

PubMed1996

[Influence of social environments on brain aging].

To investigate influence of social activity on normal brain aging, we studied the social activity score, cognitive functions, self-rating depression scale, cerebral blood flow (CBF), MRI and motor function in the normal elderly people living in different social environments. There was no difference in risk factors for stroke, MRI findings and CBF between the two groups. However, the subjects living in a home for elderly showed significantly lower social activities than those living with families. Cognitive functions and motor function were lower, and SDS was higher in subjects living in retirement house than those living with families. The social environment including social activities closely related to life style may significantly influence brain aging with regard to silent brain infarctions or risk factors for stroke.

Aged↗