Biomedical subjects

M Iwasaki

Publications and source records attributed to M Iwasaki.

At least 145 records · Page 8Linked to original sources

PubMed1999

Influence of clenching intensity on bite force balance, occlusal contact area, and average bite pressure.

It has been difficult for investigators to simultaneously and reliably evaluate bite force in the intercuspal position with the area and location of occlusal contacts. This study was designed to investigate the variations in these parameters with respect to two factors: three levels of clenching and the preferred chewing side. Human subjects with normal occlusion were examined with a recently developed system (Dental Prescale Occluzer, Fuji Film, Tokyo, Japan). The three levels of clenching intensity were assessed by masseteric EMG activity and included the maximum voluntary contraction, and 30% and 60% of the maximum. The results indicated that the bite force and occlusal contact area on the whole dental arch increased with clenching intensity. In contrast, the average bite pressure, obtained by dividing the bite force by the contact area, remained unchanged regardless of the clenching intensity. As the clenching intensity increased, the medio-lateral position of the bite force balancing point shifted significantly (P<0.01) from the preferred chewing side toward the midline. The antero-posterior position remained stable in a range between the distal third of the first molar and the mesial third of the second molar. The bite force and occlusal contact area, which were mainly on the molars, increased with the clenching intensity, whereas the proportions of these two variables on each upper tooth usually did not change significantly. The exception was the second molar on the non-preferred chewing side. When comparisons were made between pairs of specific upper teeth of same name, usually no significant difference was found in bite force or occlusal contact area, regardless of the clenching level. Again, the exception to this observation was the second molar on the preferred chewing side, which had a larger area at the 30% clenching level. The results in normal subjects suggest that as the clenching intensity increases in the intercuspal position, the bite force adjusts to a position where it is well-balanced. This adjustment may prevent damage and overload to the teeth and temporomandibular joints.

Adult↗

PubMed1999

Age-dependent effects of hedgehog protein on chondrocytes.

Bone morphogenetic protein (BMP) has a crucial role in osteochondrogenesis of bone formation as well as in the repair of fractures. The interaction between hedgehog protein and BMPs is inferred from recent molecular studies. Hedgehog genes encode secreted proteins which mediate patterning and growth during skeletal development. We have shown that Indian hedgehog gene (Ihh) is expressed in cartilage anlage and later in mature and hypertrophic chondrocytes. This finding suggests that Ihh may regulate the development of chondrocytes. Our results in this study have shown that Ihh transcripts were expressed in hypertrophic chondrocytes in mice at three days but not at three weeks, although a similar expression pattern of alpha1 (X) collagen could be observed in both types of cartilage. To investigate the possibility that there are direct and age-dependent functions of Ihh in chondrocytes, cultured chondrocytes were treated with the amino-terminal fragment of Sonic hedgehog protein (Shh-N) which can functionally substitute for Ihh protein. Shh-N did not affect the proliferation and differentiation of chondrocytes from three-week-old mice but had a significant effect on three-day-old mice. It enhanced proliferation up to 128% of the control culture in a dose-dependent manner. Although there was no effect in Shh-N-treated cultures, Shh-N enhanced the stimulatory effect of parathyroid hormone (PTH) on the synthesis of proteoglycans. Because the effects of Shh-N on chondrocyte differentiation in this culture system differed from those of bone morphogenetic protein-2 (BMP2) and PTH, in terms of proteoglycan synthesis and ALPase activity, it is unlikely that BMP2 or PTH/PTH-related protein mediates the direct effects of Ihh in chondrocytes. Our study shows that Ihh can function in chondrocytes in a direct and age-dependent fashion.

Aging↗

PubMed1999

Impaired diurnal cardiac autonomic function in subjects with type 2 diabetes.

OBJECTIVE: To assess diurnal cardiac sympathetic and parasympathetic nerve functions in diabetic subjects with variable diabetic neuropathy. RESEARCH DESIGN AND METHODS: Frequency domain analysis of 24-h Holter ECG was done for 132 diabetic subjects (84 without any symptomatic neuropathy; 37 with only symptomatic peripheral neuropathy; 11 with symptomatic autonomic neuropathy) and 57 normal volunteers to calculate the low frequency (LF) component representing the beta-adrenoceptor function and the high frequency (HF) component representing the cardiac parasympathetic nerve function. RESULTS: Cardiac LF and HF components in diabetic subjects without peripheral neuropathy showed values comparable to those of normal volunteers and a similar circadian rhythm. Diabetic subjects with peripheral neuropathy or autonomic neuropathy showed significantly depressed LF and HF components and loss of the circadian rhythm of LF and HF components compared with diabetic subjects without neuropathy. Impairment of the LF component in the afternoon could be accounted for by the duration of diabetes and elevated HbA1c level. Impairment of the HF component at night could be accounted for by the duration of diabetes but not an elevated HbA1c level. CONCLUSIONS: These data indicated that diabetic subjects with peripheral neuropathy and diabetic subjects with symptomatic autonomic neuropathy, but not diabetic subjects without neuropathy, showed a marked decrease in cardiac sympathetic and parasympathetic nerve functions and loss of circadian rhythm.

Adult↗

PubMed1999

Rapid decalcification using microwaves for in situ hybridization in skeletal tissues.

In situ hybridization histochemistry is the sole tool available for detecting the localization and expression of specific RNA on histological sections under various in vivo conditions. For this paper, we examined the effect of microwave exposure on the time needed for decalcification of skeletal tissues and on the preservation of sensitivity for hybridization signals. Our data show that the use of microwave decalcification reduces the decalcification period while preserving intense hybridization signals for mouse alpha1 chain of procollagen type I mRNA in osteogenic cells in bone. The use of microwave treatment to decalcify skeletal tissues may prevent delay in obtaining experimental results or the loss of signals during in situ hybridization.

Animals↗

PubMed1999

Thoracoscopic diagnosis and treatment of mediastinal masses. Usefulness of the Two Windows Method.

BACKGROUND: We report on the usefulness of thoracoscopic surgery by the Two Windows Method in mediastinal diseases. While the positioning of the two-window skin incisions was originally decided for lung cancer, but we have been using precisely the same method to biopsy and remove mediastinal lesions. METHODS: Thoracoscopic surgery by the Two Windows Method was performed in 40 cases in which it had been impossible to make a diagnosis by noninvasive methods. Access to the pleural cavity was achieved by making skin incisions in two places anterior and posterior to the inferior angle of the scapula in the fourth intercostal space. RESULTS: Biopsy was performed in 17 of the 40 patients to make a histological diagnosis. It was possible to make a definitive histological diagnosis in all of the patients. Complete resection of a mediastinal tumor was performed in 23 patients, and the resection was concluded thoracoscopically by the Two Windows Method in 22 of these patients (95.7%), with the only exception of one patient in whom we converted to standard thoracotomy because of intraoperative bleeding. There were no postoperative complications and no perioperative deaths. CONCLUSIONS: We conclude that the Two Windows Method is also useful for the diagnosis and complete resection of mediastinal diseases and that this is a low-invasive and safe method.

Adolescent↗

PubMed1999

[Ruptured middle cerebral artery aneurysm successfully treated by intra-aneurysmal GDC embolization in a patient with idiopathic thrombocytopenic purpura: a case report].

We report a case of a ruptured middle cerebral artery (MCA) aneurysm treated by an intra-aneurysmal Guglielmi detachable coil (GDC) embolization in a patient with idiopathic thrombocytopenic purpura (ITP). A 57-year-old female, who had been suffering from ITP for 4 years, experienced sudden severe headache. She was diagnosed as having subarachnoid hemorrhage due to a ruptured MCA aneurysm and the hematological examination showed moderate thrombocytopenia. Considering the risk of open surgery, we treated the aneurysm by intra-aneurysmal GDC embolization in the acute stage and platelet transfusion was carried out after the therapy. She had a good clinical course and recovered without any complications or neurological symptoms. The follow-up cerebral angiogram at 1 week and 2 years after the treatment showed complete obliteration of the aneurysm. Recently, endovascular treatment tends to be applied to surgically high-risk patients. A GDC embolization for a patient with thrombocytopenia has rarely been reported and the risk and efficacy is unknown. So, we conclude that for a patient with thrombocytopenia, intra-aneurysmal GDC embolization could be adopted as one of the less invasive treatment for ruptured aneurysm.

Aneurysm, Ruptured↗

PubMed1999

Usefulness of video-assisted thoracic surgery (Two Windows Method) in the treatment of lung cancer for elderly patients.

BACKGROUND: We have been performing it less invasively by making just two, small skin incisions (Two Windows Method) for lung cancer surgery. We assess the usefulness of VATS by the Two Windows Method in elderly patients. METHODS: The subjects were 32 of the 75-year-old or older patients with primary lung cancer in our department. We assessed cases in which thoracotomy was performed and the cases in which VATS by Two Windows Method was performed, and compared postoperative complications, hospital deaths, and postoperative length of stay. RESULTS: Operations by video-assisted thoracic surgery (VATS) by the Two Windows Method were completed in 20 of the 32 patients, and a conversion to thoracotomy was done in two patients (rate 9%). Ultimately, thoracotomy was performed in a total of 12 cases, including these two. In the thoracotomy patients, the most common postoperative complication was pneumonia/atelectasis (4 cases) secondary to poor sputum expectoration. There were 2 hospital deaths due to septicemia, and there was 1 due to pulmonary artery embolism. In the VATS patients, the rate of occurrence of postoperative complications was 30%, and clearly lower than the 67% among the thoracotomy patients (p<0.05). No hospital death occurred among the VATS patients. The postoperative hospital stay of the VATS patients (21 days) was shorter than that of the thoracotomy patients (31 days), (p<0.05). CONCLUSIONS: VATS by the Two Windows Method is safer than thoracotomy, and it should be considered first for lung cancer surgery in the aged.

Adenocarcinoma↗

PubMed1999

[Primary hyperchylomicronemia and gene defects].

Primary Hyperchylomicronemia is known as a syndrome in which the accumulation of chylomicron occurs in the circulation. The main clinical symptoms of this disorder are the huge increase in plasma trigriceride and cholesterol, and the presence of xanthomatous eruption, lipemia retinalis, hepatosplenomegaly, and the complication of acute pancreatitis. With gene analysis, a deficiency of lipopreteinlipase (LPL) or apolipoprotein C-II is revealed as a main cause of primary chylomicronemia. Furthermore, in some cases, abnormalities of remnant receptors, the presence of antibody against LDL, apolipoprotein C-II, and LDL receptor are reported as causes of chylomicronemia syndrome. In the present paper, we summarized the major gene polymorphism and characteristics of clinical symptom of these disease.

Apolipoprotein C-II↗

PubMed1998

Requirement for distinct Janus kinases and STAT proteins in T cell proliferation versus IFN-gamma production following IL-12 stimulation.

While IL-12 is known to activate JAK2 and TYK2 and induce the phosphorylation of STAT4 and STAT3, little is known regarding how the activation of these signaling molecules is related to the biologic effects of IL-12. Using an IL-12-responsive T cell clone (2D6), we investigated their requirements for proliferation and IFN-gamma production of 2D6 cells. 2D6 cells could be maintained with either IL-12 or IL-2. 2D6 lines maintained with IL-12 (2D6(IL-12)) or IL-2 (2D6(IL-2)) exhibited comparable levels of proliferation, but produced large or only small amounts of IFN-gamma, respectively, when restimulated with IL-12 after starvation of either cytokine. 2D6(IL-12) induced TYK2 and STAT4 phosphorylation. In contrast, their phosphorylation was marginally induced in 2D6(IL-2). The reduced STAT4 phosphorylation was due to a progressive decrease in the amount of STAT4 protein along with the passages in IL-2-containing medium. 2D6(IL-12) and 2D6(IL-2) similarly proliferating in response to IL-12 induced comparable levels of JAK2 activation and STAT5 phosphorylation. JAK2 was associated with STAT5, and IL-12-induced STAT5 phosphorylation was elicited in the absence of JAK3 activation. These results indicate that IL-12 has the capacity to induce/maintain STAT4 and STAT5 proteins, and that TYK2 and JAK2 activation correlate with STAT4 phosphorylation/IFN-gamma induction and STAT5 phosphorylation/cellular proliferation, respectively.

Animals↗

PubMed1998

Topography of modular subunits in the mushroom bodies of the cockroach.

The mushroom body (MB), a conspicuous neuropil structure in the insect brain, is implicated in associative memory and in some aspects of motor control. Intrinsic neurons of the MB (Kenyon cells) extend dendrites into the calyx, and their axons run through the pedunculus and then bifurcate to form the alpha and the beta lobes. At the pedunculus and the lobes, Kenyon cells make synaptic connections with dendrites of extrinsic (output) neurons. Previously, we reported that the alpha lobe of the cockroach MB consists of repetitive modular subunits (Mizunami et al. [1997] Neurosci. Lett. 229:153-156). Each subunit is composed of a dark layer and a light layer, and the layers are refereed to as slabs. Each slab is composed of axons of a specific subset of Kenyon cells. In the present study, we examined serial sections of reduced silver preparations and found that each dark and light slab continues throughout the length of the pedunculus and the alpha and beta lobes. We also found that Golgi-impregnated Kenyon cells often exhibit a characteristic grouping, forming a thin sheet interlaced by dozens or hundreds of axons. The sheet is much thinner than the slab, and each sheet remains within a particular slab throughout the length of the pedunculus and the lobes. Thus, the sheet is a component forming the slab. In the pedunculus and the beta lobe, a class of Golgi-impregnated extrinsic neurons exhibit segmented dendritelike arbors that interact with every other slab, i.e., either with only dark or light slabs. Because each neuron of this class interacts with each particular set of dark or light slabs, we conclude that the slabs are units for transmitting output signals from the MB.

Animal Structures↗

PubMed1998

Topography of four classes of Kenyon cells in the mushroom bodies of the cockroach.

Mushroom bodies (MBs), which are higher centers in the insect brain, are implicated in associative memory and in the control of some behaviors. Intrinsic neurons of the MB, called Kenyon cells, receive synaptic inputs from axon terminals of input neurons in the calyx. Axons of Kenyon cells project into the pedunculus and to the alpha and beta lobes, where they make synaptic connections with dendrites of extrinsic (output) neurons. In this study, we examined the morphology of Kenyon cells in the cockroach by using Golgi stains and found that they can be classified into four classes (K1, K2, K3, and K4), according to the diameter, location, and morphology of the cell bodies, dendrites, and axons. The somata of Kenyon cells of different classes occupy different concentric zones; K1 cells occupy the most central zone, and K4 cells occupy the most peripheral zone. The main processes of Kenyon cells of different classes also occupy different concentric zones in the calyx. Dendrites of K2 and K3 cells are distributed throughout the calycal neuropil, whereas those of K1 and K4 cells cover the outer and inner halves of the depth of the neuropil, respectively. In the pedunculus and the alpha and beta lobes, axons of Kenyon cells of different classes occupy different zones, although the separation is not complete. A class of extrinsic neurons in the a lobe has dendrite-like arbors that cover the zones where either K1, K2, or K3 are located. These neurons probably transmit signals of each class of Kenyon cells. We conclude that, in the cockroach, four classes of Kenyon cells subdivide the cell body region, pedunculus, and lobes of the MBs, whereas subdivision is less prominent in the calycal neuropil.

Animal Structures↗

PubMed1998

Multiple roles of interferon-gamma in the mediation of interleukin 12-induced tumor regression.

Administration of recombinant interleukin 12 (IL-12) induces tumor regression that is associated with T-cell infiltration in the OV-HM ovarian carcinoma and CSA1M fibrosarcoma models. After confirming the blocking of regression by injection of anti-IFN-gamma monoclonal antibody (mAb), we investigated the mechanisms underlying the requirement of IFN-gamma in T-cell migration and tumor regression. T-cell migration was inhibited by injection of anti-IFN-gamma mAb to OV-HM tumor-bearing mice prior to IL-12 treatment. We examined, using the lymphoid cell migration assay, whether IFN-gamma is required for enhancing the migratory capacity of T cells or the T cell-accepting potential of tumor masses during IL-12 treatment. Spleen cells from IL-12-treated or untreated OV-HM-bearing mice were stained in vitro with a fluorescein chemical and transferred i.v. into OV-HM-bearing mice that were not treated with IL-12. Migration of donor cells was quantitated by counting the number of fluorescent cells on cryostat sections of tumor masses from recipient mice. Compared to spleen cells from OV-HM-bearing mice that were not treated with IL-12, enhanced migration was observed for cells from IL-12-treated OV-HM-bearing mice. Anti-IFN-gamma pretreatment of donor mice before IL-12 treatment did not reduce the migratory capacity of T cells, whereas migration was markedly inhibited in recipient mice injected with anti-IFN-gamma. Anti-IFN-gamma pretreatment decreased vascular cell adhesion molecule-1 (VCAM-1)-/intercellular adhesion molecule-1 (ICAM-1)-positive blood vessels at tumor sites. Consistent with this, migration was also inhibited by treatment of recipient mice with either anti-VCAM-1 or anti-ICAM-1 mAb. In contrast to the OV-HM model, T-cell migration was not affected in the CSA1M model following preinjection of anti-IFN-gamma mAb. In this model, VCAM-1-/ICAM-1-positive blood vessels existed even after anti-IFN-gamma treatment, although tumor regression was completely inhibited. These results indicate that IFN-gamma plays two distinct roles in expressing the antitumor efficacy of IL-12: one is to support the T-cell acceptability of tumor masses, and the other is to mediate the antitumor effects of migrated T cells.

Animals↗

PubMed1998

A lymphocyte-specific CC chemokine, secondary lymphoid tissue chemokine (SLC), is a highly efficient chemoattractant for B cells and activated T cells.

Secondary lymphoid tissue chemokine (SLC) is a CC chemokine expressed mainly in lymph nodes, appendix and spleen, and specifically chemotactic for lymphocytes (Nagira et al., J. Biol. Chem. 1997. 272: 19518-19524). Here, we carried out transendothelial migration assays to determine the classes and subsets of lymphocytes migrating toward SLC. SLC attracted freshly isolated B cells with high efficiency and T cells modestly. Thus, SLC is the first CC chemokine with a strong chemotactic activity on fresh B cells. Among T cell types and subsets, SLC broadly attracted CD4+ and CD8+ cells, CD45RO- (naive) and CD45RO+ (memory) cells, and CD26high (activated) and CD26low- (resting) cells. SLC also attracted both L-selectin+ and L-selectin- subpopulations of various T cell subsets and B cells. Furthermore, mitogenic stimulation strongly enhanced migratory responses of T cells and B cells toward SLC. By in situ hybridization, SLC mRNA was detected in the cortical parafollicular regions (the T cell areas) of a lymph node and an appendix. Collectively, SLC may be a basic chemokine supporting homeostatic migration of a broad spectrum of lymphocytes into the secondary lymphoid tissues. SLC may also be involved in immune responses by inducing highly efficient migration of T and B cells following antigenic stimulation.

Adult↗

PubMed1998

Slight difference in primary amino acid sequence of p17 matrix protein of HIV-1 exerts profound influence on its antigenicity.

HIV-1 p17 antigen has been studied for its biological significance in vitro as well as its immunological roles in vivo. By immunological approach of antibody-binding to HIV-1 p17 antigens of several subtypes in combination with computerized analysis of those tertial structures, it became evident that, irrelevant of similarity of linear amino acid sequence of different HIV-1 subtypes, a few amino acid substitutions close to or distant from specified epitope(s) affected their tertial structure resulting in change in ability of its binding to selected antibody. ELISA employing two monoclonal antibodies, A144 and C415, could detect p17 of subtypes A and B, but not of subtypes C, D, and E. Since the epitope site corresponding to A144 has been reported to be important for biological activity of p17 of HIV-1, change in tertial structure around this epitope may explain some difference in biology of HIV-1, such as infectivity of subtypes B and E.

Amino Acid Sequence↗

PubMed1998

Experience with the two-windows method for mediastinal lymph node dissection in lung cancer.

BACKGROUND: Continuing to refine minimally invasive thoracoscopic surgical procedures, we have established the two-windows method. METHODS: Skin incisions required by this method consist of a 2- to 3-cm skin incision posteriorly, and a 2- to 3-cm skin incision anteriorly in the fourth intercostal space, with the inferior angle of the scapula as the midpoint. We used this method to perform pulmonary lobectomies in combination with thoracoscopy and mediastinal lymph node dissection in 100 consecutive patients with lung cancer (preoperative diagnosis, stage I, T1 N0 M0). RESULTS: The mean operative time was 2 hours 46 minutes, the mean blood loss was 68.2 mL, and the mean number of mediastinal lymph nodes dissected was 24.3. In developing this minimally invasive thoracoscopic procedure, which facilitates mediastinal lymph node dissection, we realized that it is best performed through the fourth intercostal space. Because the tracheal bifurcation can be seen directly below this level, surgical manipulation in this area can be easily performed. This enables the same extent of mediastinal lymph node dissection as that performed during a standard thoracotomy. Another advantage of this method is that a standard posterolateral thoracotomy incision can be made whenever necessary by simply connecting the two incisions. CONCLUSIONS: We believe that the two-windows method is capable of serving as the standard method for the surgical treatment of stage I lung cancer.

Adult↗

PubMed1998

Advanced glycosylation end products in adrenal lipofuscin.

The present study examined the presence of advanced glycosylation end products (AGEs) in lipofuscin present in the brain and adrenal gland of aging rats by immunohistochemistry using antibodies raised against AGEs. Lipofuscin identified as yellow to brown granules emitting bright yellow to orange autofluorescence with ultraviolet light were detected in cortical neurons, cerebellar Purkinje cells, and adrenal cells in the inner part of the zona reticularis. However, none of the antibodies visualized lipofuscin in these areas. The outer part of the zona reticularis contained yellow granules emitting a faint orange autofluorescence. These granules were immunostained by an antibody that reacted with AGEs structures unrelated to the carboxymethyllysine moiety. Newly formed adrenal cortical cells are thought to migrate from the outer layer to the inner layer of the zona reticularis. Therefore, our results suggest that glycosylation-related processes are involved in lipofuscinogenesis, at least in its early stage, in the adrenal zona reticularis.

Adrenal Cortex↗

PubMed1998

No difference in seroprevalences of Helicobacter pylori infection between patients with pulmonary tuberculosis and those without.

A previous article reported a possible relationship between a history of tuberculosis and Helicobacter pylori infection. Epidemiologic similarities exist between the two infections: Mycobacterium tuberculosis and H. pylori are transmitted from person to person and the risk of acquiring them is elevated in underprivileged environment. This study was conducted to investigate the relationship between the two infections. Serum concentrations of anti-H. pylori IgG antibody were measured in 40 tuberculosis inpatients on antituberculosis chemotherapy for no more than 3 months (group I; 52.4 +/- 21.4 years of age), 43 tuberculosis inpatients on it for more than 3 months (group II; 57.3 +/- 16.3 years), and 60 nontuberculosis outpatients (control subjects; 55.9 +/- 16.7 years). H. pylori seropositivities were similar among control subjects (73.3%), group I (65%), and group II (69.8%). The difference in the antibody concentrations was significant between control subjects and group I (353.7 +/- 321.2 vs. 176.5 +/- 197.9 U/ml) but was not significant between control subjects and group II (353.7 +/- 321.2 vs. 229.9 +/- 249.5 U/ml). The seroprevalences may not be different between patients with pulmonary tuberculosis and those without, and antituberculosis therapy may not decrease the antibody concentrations.

Adolescent↗

PubMed1998

Detection of HIV-Gag p24-specific antibodies in sera and saliva of HIV-1-infected adults and in sera of infants born to HIV-1-infected mothers.

Secretory immunoglobulin A (IgA) is known to play an important role in the mucosal defense against a variety of pathogens. Although the role of IgA antibodies during sexual transmission of HIV is not clear, HIV-specific IgA antibodies have been detected in various mucosal secretions of HIV-infected individuals. Using a monoclonal antibody against human IgA, we established an ELISA system to detect anti-HIV p24 IgA antibodies in sera and saliva. We have analyzed the levels of anti-HIV p24 IgG and IgA antibodies in sera and saliva of 107 and 119 adults, respectively, with HIV infection at different clinical stages, and in the sera of 13 infants born to HIV-infected mothers. The level of anti-HIV p24 IgA antibodies was lower in sera and higher in saliva as compared to that of anti-HIV p24 IgG antibodies. Where the percentage of HIV-specific serum antibody-positive cases decreased with disease progression, that of saliva antibody-positive cases increased in AIDS patients. Among the 13 infants born to HIV-infected mothers, 7 infants were HIV-p24-specific serum IgA positive. These sera were negative for anti-HIV p24 secretory IgA, suggesting that some infants develop their own immune responses against HIV infection. Thus, the detection of HIV-specific IgA antibodies, especially in saliva, could be a simple and reliable test for the diagnosis of HIV infection.

AIDS Serodiagnosis↗