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Biomedical subjects

K Okamoto

Publications and source records attributed to K Okamoto.

At least 55 records · Page 3Linked to original sources
PubMed2003

Response properties of TMJ units in superficial laminae at the spinomedullary junction of female rats vary over the estrous cycle.

Neurons responsive to stimulation of the temporomandibular joint (TMJ) region were recorded from superficial laminae at the trigeminal subnucleus caudalis/upper cervical cord (Vc/C(2)) junction region of cycling female rats under barbiturate anesthesia. To determine if receptive field (RF) properties or sensitivity to algesic chemicals of TMJ units vary over the estrous cycle, animals were selected from proestrous (high estrogen) or early diestrous (low estrogen) stages. More than 90% of TMJ units from each group received convergent nociceptive input [wide dynamic range (WDR) or nociceptive specific (NS)-like] from facial skin. The cutaneous high-threshold RF areas of WDR units from proestrous rats were 30% larger than diestrous units, while RF areas of NS units were similar. Bradykinin (BK, 0.1-10 microM) injection into the TMJ region excited a high percentage of units (>80% of total) from both groups in a dose-related manner. However, BK-evoked response magnitude (R(mag), +140%) and duration (+64%) were greater for proestrous than diestrous units. Both WDR and NS-like TMJ units of proestrous females displayed enhanced BK-evoked R(mag) values and response duration. Glutamate or mustard oil excitation of TMJ units was not affected by stage of the estrous cycle. Several TMJ units from proestrous and diestrous females were activated antidromically from the contralateral posterior thalamus, indicating that projection and nonprojection units were included in the sample population. These results were consistent with the hypothesis that factors related to stage of the estrous cycle modify the processing of deep craniofacial inputs by superficial dorsal horn neurons at the spinomedullary junction, a key region for the initial integration of sensory signals from the TMJ.

Animals↗
PubMed2003

Target affinities of faropenem to and its impact on the morphology of gram-positive and gram-negative bacteria.

Faropenem is a new oral beta-lactam antibiotic unique from carbapenems and other available beta-lactams. Determinants of the in vitro activity of beta-lactam antibiotics include affinity to penicillin-binding proteins (PBPs) and beta-lactamase stability. In this study, the binding affinity of faropenem to various PBPs and its impact on the morphology of Staphylococcus aureus and Escherichia coli were evaluated. In general, faropenem demonstrated high binding affinity to high-molecular-weight PBPs but low affinity to low-molecular-weight PBPs. In S. aureus and Streptococcus pneumoniae, faropenem exhibited high binding affinity to PBP1, followed by PBP3 and PBP2. In E. coli, faropenem showed the highest affinity for PBP2, followed by PBP1A, PBP1B, PBP3 and PBP4. In Proteus vulgaris, binding was highest to PBP4, followed by PBP1A, PBP2 and PBP3. In Serratia marcescens, faropenem bound preferentially to PBP2 and PBP4. Exposure of S. aureus to faropenem at minimum inhibitory concentrations (MICs) of 1/8 or 1/4 resulted in irregular septum formation. At 1x MIC or higher, a larger number of lysed cells were observed. Exposure of E. coli to 1/8x MIC or 1/4x MIC also induced changes in cellular shape; the normal rod-shaped form changed to a spherical form in a time-dependent manner. After exposure of E. coli to 1x MIC for 2 h, bulging-shaped E. coli cells were observed and after 4 h of exposure cell lysis was demonstrated. In the presence of 4x MIC, spheroplast-like forms and cell lysis were observed. The morphological changes triggered by faropenem are in agreement with the PBP binding affinities reported. Thus, the high binding affinities of faropenem to PBPs from gram-negative and gram-positive bacteria are mirrored by its pronounced and concentration-dependent bactericidal effect.

Anti-Bacterial Agents↗
PubMed2003

Beta-lactamase stability of faropenem.

Faropenem (FAR) is an orally available member of the penem class unique among carbapenems and other available beta-lactams. This study compared FAR to cephalosporins and imipenem with respect to beta-lactamase (BLA) stability and emergence of resistance to Staphylococcus aureus and Escherichia coli. BLA stability was studied using enzyme preparations from sonicated/centrifuged 24-hour cultures of E. coli, Enterobacter cloacae, Proteus vulgaris, Providencia rettgeri, Klebsiella pneumoniae, S. aureus, and Bacteroides fragilis grown in the presence of 20 mg/l ampicillin or cephaloridine to induce penicillinase or cephalosporinase, respectively. Substrate hydrolysis was quantitated spectrophotometrically. Multistep acquisition of resistance was promoted by growing bacteria in broth containing 2-fold dilutions of antibiotic over 10 cycles. Aliquots from test tubes with visible growth provided the inoculum for the next series of dilutions. FAR as well as other cephalosporins tested were highly stable to penicillinase derived from S. aureus and E. coli. However, E. coli- and P. vulgaris-derived cephalosporinase hydrolyzed cephaloridine, cefaclor and cefotiam considerably, whereas FAR was highly stable. FAR was highly stable against hydrolysis by various BLAs prepared from four B. fragilis strains and the rate of FAR hydrolysis by metallo-BLA was 5 times lower than that for imipenem. Additionally, the acquisition of resistant S. aureus strains was less pronounced for FAR compared to other agents tested. MICs rose 8-fold after the 10th sub-MIC exposure, while MICs rose 16-, 31- and 512-fold for cefixime, cefazolin and cefaclor, respectively. E. coli shifts in MICs were moderate for all the agents tested. In conclusion, FAR is characterized by pronounced BLA stability compared to other cephalosporins and imipenem. Furthermore, a lower propensity for resistance development with FAR as compared to cephalosporins was observed.

Anti-Bacterial Agents↗
PubMed2003

Increased vascular endothelial growth factor in acute eosinophilic pneumonia.

Acute eosinophilic pneumonia (AEP) is associated with the presence of diffuse pulmonary infiltrates on the chest radiograph and an increased number of eosinophils and an elevation of interleukin (IL)-5 levels in bronchoalveolar lavage (BAL) fluid. Vascular endothelial growth factor (VEGF) is a constitutively expressed protein encoded by messenger ribonucleic acid in human eosinophils and is released following stimulation with IL-5. However, the roles of IL-5 and VEGF in the pathogenesis or activity of this disease have not been clarified. The authors investigated the cells and the levels of these two factors in BAL fluid in five AEP patients and five normal controls before and after corticosteroid treatment. The absolute number of eosinophils-mL(-1), IL-5 and VEGF levels in patients before treatment were higher than in controls (53.8 versus 0.3 x 10(4) x mL(-1), 490.1 versus 5.2 pg x mL(-1) and 643.0 versus 133.9 pg x mL(-1), respectively). IL-5 and VEGF rapidly decreased to the control level in parallel with clinical improvement. The relationship between eosinophilia and IL-5 and VEGF levels was strongly significant. Elevated interleukin-5 in the lung may initiate the recruitment of eosinophils and enhance the release of mediators, such as vascular endothelial growth factor from eosinophils, which, in turn, increases the permeability of blood vessels.

Acute Disease↗
PubMed2003

Disseminated Mycobacterium avium complex (DMAC) in an immunocompetent adult.

A female patient with multiple osteomyelitis and pulmonary Mycobacterium avium disease visited an orthopaedic clinic with back pain. Systemic bone scan showed multiple sites of increased radioactivity in the vertebral bodies, right scapula, femurs and ribs. M. avium was isolated from sputum and a sample aspirated from the right scapula. The route of infection was unknown as there was no history of trauma or surgery. HIV testing was negative. As there was no underlying immunological disease she was diagnosed as disseminated M. avium complex (DMAC) disease in an immunocompetent adult. Cytokine production on several stimuli from peripheral blood mononuclear cells was similar to that in pulmonary M. avium patients. Sequence analysis of IFN-gamma receptor revealed no nucleotide substitution. We detected serotypes 1, 2 and 4 from mycobacteria cultured from the right scapula, and conclude that this case could be the result of undetected immune deficiency and/or unrecognised virulence of the infecting isolate.

Female↗
PubMed2003

Impaired interleukin-1beta converting enzyme (ICE) activity in patients with pulmonary tuberculosis.

We measured the activity of IL-1beta converting enzyme (ICE) of monocytes from pulmonary tuberculosis (PTB) patients. Peripheral blood mononuclear cells (PBMCs) and serum were collected from PTB patients (n = 16) and healthy subjects (n = 6). Serum IL-18 levels were significantly higher in PTB patients (515.9 +/- 326.5 pg/ml) than in controls (108.7 +/- 65.2 pg/ml) (P < 0.01), but gradually decreased with tuberculosis therapy. ICE activity was significantly lower in TB patients (65.3 +/- 34.4 vs. 142.2 +/- 75.6 U/mg) (P < 0.05). Serum IL-18 levels inversely correlated with ICE activity (P < 0.05). Altered ICE activity may explain why there is reduced IFN-gamma production from PBMCs; however, serum IL-18 is probably not regulated by ICE in monocytes in TB patients.

Caspase 1↗
PubMed2002

YbRh2Si2: spin fluctuations in the vicinity of a quantum critical point at low magnetic field.

We report a 29Si NMR study on aligned single crystals of YbRh2Si2 which shows behavior characteristic of a quantum critical point (QCP: T(N)-->0). The Knight shift K and the nuclear spin-lattice relaxation rate 1/T(1) of Si show a strong dependence on the external field H, especially below 5 kOe. At the lowest H used in this measurement (H approximately 1.5 kOe), it was found that 1/T(1)T continues to increase down to 50 mK, whereas K stays constant with a large magnitude below 200 mK. This result strongly suggests the development of antiferromagnetic fluctuations with finite q vectors that compete with q=0 spin fluctuations in the vicinity of the QCP near H=0.5 kOe.

Journal Article↗
PubMed2002

MRI of high-grade astrocytic tumors: early appearance and evolution.

The clinical management and prognosis of patients with diffusely infiltrating astrocytomas are dependent on neuropathological grading of the tumors. The characteristics of MR images of high-grade astrocytic tumors are well known, but the early MRI appearance and the MRI evolution of high-grade astrocytic tumors have rarely been examined. We retrospectively reviewed MR images obtained from 4 months to 3 years and 3 months before admission, as well as MR images on admission, for five patients with pathologically proven high-grade astrocytic tumors (two glioblastomas and three anaplastic astrocytomas). In two patients, neoplastic lesions were not detectable on initial MRI, even retrospectively. In the remaining three patients, however, hyperintense areas with little or no mass effect were demonstrated on T2-weighted imaging. These lesions were misinterpreted as non-neoplastic processes, such as ischemic lesion or infarction, or demyelinating processes. All tumors showed gadolinium enhancement on admission, that emerged from the previously existing hyperintense areas on T2-weighted images without gadolinium enhancement, except for one de novo glioblastoma. Development of a small central cyst without gadolinium enhancement was demonstrated in one case before the emergence of an enhancing area.

Adult↗
PubMed2002

Atrophy of the basal ganglia as the initial diagnostic sign of germinoma in the basal ganglia.

Germ-cell tumors of the central nervous system generally develop in the midline, but the tumors can also occur in the basal ganglia and/or thalamus. However, MR images have rarely been documented in the early stage of the tumor in these regions. We retrospectively reviewed MR images obtained on admission and approximately 3 years earlier in two patients with germinoma in the basal ganglia, and compared them with CT. In addition to hyperdensity on CT, both hyperintensity on T1-weighted images and a small hyperintense lesion on T2-weighted images were commonly seen in the basal ganglia. These findings may be early MRI signs of germinoma in this region, and the earliest and most characteristic diagnostic feature on MRI was atrophy of the basal ganglia, which was recognizable before development of hemiparesis.

Adolescent↗
PubMed2002

A new technique for two-trocar laparoscopic cholecystectomy.

BACKGROUND: New techniques for laparoscopic cholecystectomy (LC) that reduce the number of trocars or use very thin instruments have been devised with the goal of further minimizing surgical invasiveness. METHODS: We performed two-trocar LC using an original new technique in 70 consecutive patients. A 10-mm trocar and a 5-mm trocar were inserted in the subumbilical and epigastrium positions, respectively. A 2-mm grasper forceps was inserted directly without a trocar below the costal margin. The fundus of the gallbladder was ligated and lifted up with a folded 0 silk string and a 16-gauge vessel cannula. RESULTS: The mean operative time was 73.2 +/- 23.5 min. A third trocar was added in two cases. None of the patients required conversion of the procedure to an open cholecystectomy, and there were no intraoperative complications. CONCLUSION: Based on our experience, we think that this technique is as safe and effective as the classic four-trocar technique; moreover, it has a cost benefit.

Adult↗
PubMed2002

Pseudouridine, an antimutagenic substance in beer towards N-methyl-N'-nitro-N-nitrosoguanidine (MNNG).

Previously we reported that beer is antimutagenic against several food-derived mutagens including heterocyclic amines. We describe here the isolation and identification of pseudouridine from beer as an antimutagenic substance against N-methyl-N'-nitro-N-nitrosoguanidine (MNNG). All of the 17 samples of beer tested showed inhibition of the MNNG mutagenicity in Salmonella. Extensive fractionation through chromatography of the active components from a freeze-dried beer sample gave six antimutagenic fractions. One contained pseudouridine, as characterized by the UV spectra, nuclear magnetic resonance, and co-chromatography in HPLC. Pure pseudouridine inhibited the mutagenicity of MNNG in a dose-dependent manner. The amount of pseudouridine in the beer sample, estimated at about 0.4 mg/100 ml beer, can account for 3% of the total antimutagenicity of beer. Thus, the major active components in beer remain to be identified. The role of pseudouridine in inhibiting the mutagenicity of MNNG is to be studied further. Among analogs of pseudouridine, spongouridine, but not uridine, was antimutagenic against MNNG. The bacterial mutagenicity of another methylating agent N-methyl-N-nitrosourea was also inhibited by pseudouridine. Pseudouridine is the first example among nucleosides to be shown to possess an antimutagenic property.

Antimutagenic Agents↗
PubMed2002

Process of apoptosis induced by TNF-alpha in murine fibroblast Ltk-cells: continuous observation with video enhanced contrast microscopy.

Apoptosis is originally defined by unique morphological changes of dying cells, and the biochemical hallmark associated with apoptosis is internucleosomal DNA fragmentation. However, few report has shown the precise time course of the apoptotic events. The present study was designed to try to clarify apoptotic processes using a video-enhanced contrast-differential interference contrast (VEC-DIC) microscopy. The morphological changes of murine fibroblast Ltk-cells treated with TNF-alpha were divided into four stages: (i) pre-apoptotic, (ii) cytoplasmic shrinkage, (iii) membrane blebbing, and (iv) ballooning. Almost of the cells underwent cytoplasmic shrinkage and membrane blebbing within 6 hours after TNF-alpha exposure, and at about 9 hours, they were in the ballooning stage. Based on these data, we investigated the relationship between morphological changes and other biochemical features. The earliest event was exposure of phosphatidyl-serine at the cytoplasmic membrane, which was already observed in the pre-apoptotic stage. Loss of mitochondrial membrane potential was observed in the cytoplasmic shrinkage stage. Caspase-8/-3 activities already started increasing in the pre-apoptotic stage, and reached their peak at 6 hours after TNF-alpha exposure. DNA fragmentation occurred in the late phase of the membrane blebbing.

Animals↗
PubMed2002

Susceptibility locus for non-obstructive azoospermia is localized within the HLA-DR/DQ subregion: primary role of DQB1*0604.

Non-obstructive azoospermia is a male infertility characterized by no or little sperm in semen as a result of a congenital dysfunction in spermatogenesis. Previous studies have reported a higher prevalence of particular human leukocyte antigen (HLA) antigens in non-obstructive azoospermia. As the expression of the RING3 gene located in the HLA class II region was predominant in the testis, mainly around spermatids and pachytene spermatocytes, it is tempting to speculate that RING3 is one of the strong candidate genes responsible for the pathogenesis of the disease. In this study, the genetic polymorphism in the RING3 gene was investigated by the direct sequencing technique. As a result, a total of 14 single nucleotide polymorphisms were identified. Among them, six were localized in the coding region but none of them was accompanied by an amino-acid substitution. No significant difference in the allelic distribution at these 14 polymorphic sites was observed between the patients and healthy controls, suggesting that the susceptible gene for non-obstructive azoospermia is not the RING3 gene. Then, in order to map the susceptibility locus for non-obstructive azoospermia precisely within the HLA region, 11 polymorphic microsatellite markers distributed from the SACM2L gene just outside the HLA class II region (187 kb telomeric of the DPB1 gene) to the OTF3 gene in the HLA class I region were subjected to association analysis in the patients. Statistical analysis of distribution in the allelic frequency at each microsatellite locus demonstrated that the pathogenic gene for non-obstructive azoospermia is located within the HLA-DR/DQ subregion. In fact, DRB1*1302 and DQB1*0604 were found to be strongly associated with non-obstructive azoospermia by polymerase chain reaction-based DNA typing. Further, haplotype analysis suggested that the DQB1*0604 allele may play a decisive role in the pathogenesis of non-obstructive azoospermia.

Alleles↗
PubMed2002

Streptococcus mutans binding to solid phase dextran mediated by the glucan-binding protein C.

Streptococcus mutans GbpC is a wall-anchored surface protein which is involved in dextran-dependent aggregation. The GbpC phenotype is observed only in cells grown under stress conditions. In order to detect the GbpC protein of S. mutans, we isolated the wall fraction following digestion of the cell wall of this organism by N-acetylmuramidase, and detected the GbpC protein from S. mutans cells by western analysis with anti-GbpC serum. Interestingly, S. mutans cells exhibiting the negative dextran(alpha-1,6 glucan)-dependent aggregation (ddag) phenotype expressed the protein and could bind to immobilized dextran.

Bacterial Adhesion↗
PubMed2002

gbpC and pac gene mutations detected in Streptococcus mutans strain GS-5.

The Streptococcus mutans gbpC gene encoding cell wall-anchoring glucan-binding protein C is involved in the dextran(alpha-1,6 glucan)-dependent aggregation (ddag) of this organism. Unlike cells of other strains of S. mutans, strain GS-5 cells did not exhibit dextran(alpha-1,6 glucan)-dependent aggregation under any conditions. We therefore hypothesized that the gbpC gene may be mutated in strain GS-5. Sequencing analysis of the 1752-nucleotide GS-5 gbpC gene revealed a point mutation that switched codon 65 to a TAA termination codon. Strain GS-5 was previously reported also to have a mutation in the pac gene encoding the cell wall-anchored major protein antigen. The laboratory-maintained strain GS-5 is regarded as having lower cariogenicity than the original isolate. The decreased cariogenicity developed during the laboratory culture of strain GS-5 may have been caused by mutations in an environment lacking appropriate selective pressures.

Antigens, Bacterial↗
PubMed2002

Epidural blood patch for treatment of spontaneous intracranial hypotension.

Spontaneous intracranial hypotension is an uncommon disease caused by cerebrospinal fluid leakage. We reported a case of a 42-year-old male with postural headache who was diagnosed as having spontaneous intracranial hypotension. His headache did not completely improve by conservative therapies, so he underwent an autologous epidural blood patch. The site of cerebrospinal fluid restoration was identified at the level from the C2 to Th7 epidural space by 111In-DPTA cisternography and computed tomography coupled with myelography, and cervical EBP was performed. Because cerebrospinal fluid drops from the catheter, it is useful to identify the location of the catheter tip under contrast injection X-ray. Rapid and dramatic relief from the headache was obtained, and no serious complications occurred.

Adult↗
PubMed2002

Treatments of hamartoma with neuroendoscopic surgery and stereotactic radiosurgery: a case report.

Hypothalamic hamartoma is a non-neoplastic tumor manifesting as gelastic seizure, precocious puberty, and abnormal behavior. Treatment of it is very complicated due to its location. We report a case of hypothalamic hamartoma treated by neuroendoscopic surgery and stereotactic radiosurgery. A 5-year-old girl presented with violent behavior, precocious puberty, gelastic seizure and atonic seizure. She was diagnosed with hypothalamic hamartoma by CT and magnetic resonance imaging at 11 months of age. Tumor size did not change, but tumor intensity had changed on the MR image at 5 years of age. Magnetic resonance spectroscopy revealed decreased N-acetylaspartate and increased choline and creatine in the tumor. After neuroendoscopic biopsy, she underwent linear accelerator stereotactic radiosurgery. But her symptoms remained unchanged for 6 months. She then underwent partial resection and laser coagulation of the tumor by a neuroendoscopic approach. After the procedure, the frequency of her seizures was remarkably decreased, and her violent behavior improved. The transventricular neuroendoscopic approach to the hypothalamus is less invasive than the radical surgery. Neuroendoscopic surgery can be one of the treatments of choice for hypothalamic hamartoma.

Brain Diseases↗