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Biomedical subjects

Y Nakajima

Publications and source records attributed to Y Nakajima.

At least 37 records · Page 2Linked to original sources
PubMed2005

[Chronic tuberculous methicillin-resistant Staphylococcus aureus (MRSA) empyema with bronchopleural fistulae treated by open window thoracostomy followed by thoracoplasty and latissimus dorsi muscle transposition].

We describe a case of chronic tuberculous methicillin-resistant Staphylococcus aureus (MRSA) empyema with bronchopleural fistulae successfully treated by open window thoracostomy followed by thoracoplasty and transposition of the latissimus dorsi muscle. A 69-year old man with a history of artificial pneumothorax for pulmonary tuberculosis was referred to our hospital with fever and purulent bloody sputum. He was diagnosed as having right chronic tuberculous empyema with bronchopleural fistulae. Immediate tube thoracostomy markedly relieved symptoms except for low-grade fever. Sputum and empyema cavity cultures were repeatedly positive for MRSA. Open window thoracostomy (5th to 7th ribs resection) was performed to control the infection. The empyema cavity was cleaned with no residual calcified pleura. His condition gradually improved and he underwent thoracoplasty and transposition of the latissimus dorsi muscle 22 months after the initial surgery. He was discharged 25 days postoperatively in good condition. Seventeen months after the curative surgery, he remains well with no evidence of recurrence. A two-stage operation, open window thoracostomy to control infection followed by thoracoplasty and transposition of the latissimus dorsi muscle, is useful in cases of chronic tuberculous MRSA empyema with bronchopleural fistulae.

Aged↗
PubMed2004

Orexin (hypocretin) effects on constitutively active inward rectifier K+ channels in cultured nucleus basalis neurons.

Orexins are excitatory transmitters implicated in sleep disorders. Because orexins were discovered only recently, their ionic and signal transduction mechanisms have not been well clarified. We recently reported that orexin A (OXA) inhibits G protein-coupled inward rectifier K+ (GIRK) channels in cultured locus coeruleus and nucleus tuberomammillaris neurons. Other work in our laboratory revealed the existence of a novel inward rectifier K+ channel (KirNB), which is located in cholinergic neurons of the nucleus basalis (NB) and possesses unique single-channel characteristics. The mean open time is considerably shorter in KirNB than in Kir2.0 channels. Constitutive activity and a smaller unitary conductance set KirNB apart from cloned Kir3.0 channels. Previously, we found that substance P excites NB neurons by inhibiting KirNB channels. Here we show that orexins suppress KirNB channel activity, likely leading to neuronal excitation. Electrophysiological studies were performed on cultured NB neurons from the basal forebrain. OXA application decreased whole cell conductance through a pertussis toxin (PTX)-insensitive G protein. The OXA-suppressed current was inwardly rectifying with a reversal potential around E(K). Single-channel recordings of NB neurons revealed that constitutively active KirNB channels were transiently inhibited by OXA. Okadaic acid pretreatment abolished the recovery. The results suggest that OXA inhibition of KirNB is mediated by a PTX-insensitive G protein (i.e., G(q/11)), which eventually results in channel phosphorylation. Recovery from this inhibition is by dephosphorylation. These results, taken together with our previous study, suggest that orexin receptors can elicit neuronal excitation through at least two families of inward rectifier K+ channels: GIRK and KirNB channels.

Animals↗
PubMed2004

Giant Nernst effect in CeCoIn5.

We present a study of Nernst and Seebeck coefficients of the heavy-fermion superconductor CeCoIn5. Below 18 K, concomitant with a field-dependent Seebeck coefficient, a large sublinear Nernst signal emerges with a magnitude drastically exceeding what is expected for a multiband Fermi-liquid metal. In the mixed state, in contrast with all other superconductors studied before, this signal overwhelms the one associated with the motion of superconducting vortices. The results point to a hitherto unknown source of transverse thermoelectricity in strongly interacting electrons.

Journal Article↗
PubMed2004

[Squamous cell bronchogenic carcinoma with syndrome of inappropriate secretion of antidiuretic hormone].

Non-small cell lung cancer with syndrome of inappropriate secretion of antidiuretic hormone (SIADH) is rare. A case of squamous bronchogenic carcinoma with SIADH is reported. A 64-year-old man was admitted with 2 cm nodule of the left lung on chest radiography. Transbronchial lung biopsy revealed the squamous cell carcinoma. His past history included hypertension and hemiparesis due to brain infarction. Serum sodium level was low (122 mEq/l) and serum osmolarity was low (271 mOsm/kgH2O). However, urine sodium level was high (82 mEg/l) and urine osmolarity was high (461 mOsm/kgH2O). Renal and adrenal function was normal. He was diagnosed with cT1N0M0 squamous bronchogenic carcinoma accompanied by SIADH. He underwent left upper lobectomy with lymph node dissection. Five months after the operation, serum sodium level returned to normal. He remains well 20 months after the operation.

Carcinoma, Bronchogenic↗
PubMed2004

[Extrapleural completion pneumonectomy combined with chest wall resection for complex aspergilloma].

Completion pneumonectomy for complex aspergilloma remains challenging for thoracic surgeons. This pneumonectomy procedure often requires extrapleural dissection. Although extrapleural dissection is effective in preventing intraoperative contamination of the operative field, it is associated with massive bleeding. In addition, when the pleura has been severely thickened, it is difficult to conduct extrapleural dissection. We herein report 2 patients who underwent an extrapleural completion pneumonectomy combined with chest wall resection. In this technique, we avoided extrapleural dissection where dense pleural adhesions existed. Instead, we performed an en-bloc chest wall resection. This technique can decrease the amount of bleeding and prevent contamination of the operative field. It can also reduce the size of post-pneumonectomy space, and decrease the chance of post-pneumonectomy empyema and bronchial stump fistula. We advocate that extrapleural completion pneumonectomy combined with chest wall resection be considered in case that extrapleural dissection is extremely difficult.

Aged↗
PubMed2003

Effects of orexin (hypocretin) on GIRK channels.

Orexins (hypocretins) are recently discovered excitatory transmitters implicated in arousal and sleep. Yet, their ionic and signal transduction mechanisms have not been fully clarified. Here we show that orexins suppress G-protein-coupled inward rectifier (GIRK) channel activity, and this suppression is likely to lead to neuronal excitation. Cultured neurons from the locus coeruleus (LC) and the nucleus tuberomammillaris (TM) were used, as well as HEK293A cells transfected with GIRK1 and 2, either human orexin receptor type 1 (OX1R) or type 2 (OX2R), mu opioid receptor and GFP cDNAs. In GTPgammaS-loaded cells, orexin A (OXA, 3 microM) inhibited GIRK currents that had previously been activated by somatostatin (in LC cells), nociceptin (TM cells), or the mu opioid agonist DAMGO (HEK cells). In guanosine triphosphate (GTP)-loaded HEK cells, in which GIRK currents were not preactivated, OXA induced a biphasic response through both types of orexin receptors: an initial current increase and a subsequent decrease to below resting levels. Current-voltage (I-V) relationships revealed that both the OXA-induced and suppressed currents are inwardly rectifying with reversal potentials around EK. The OXA-induced initial current was partially pertussis toxin (PTX) sensitive and partially PTX insensitive, whereas the OXA-suppressed current was PTX insensitive. These data suggest that orexin receptors couple with more than one type of G-protein, including PTX-sensitive (such as Gi/o) and PTX-insensitive (such as Gq/11) G-proteins. The modulation of GIRK channels by orexins may be one of the cellular mechanisms for the regulation of brain nuclei (e.g., LC and TM) that are crucial for arousal, sleep, and appetite.

Analgesics, Opioid↗
PubMed2003

Multiple superconducting phases in new heavy fermion superconductor PrOs4Sb12.

The superconducting gap structure of recently discovered heavy fermion superconductor PrOs4Sb12 was investigated by using thermal transport measurements in magnetic field rotated relative to the crystal axes. We demonstrate that a novel change in the symmetry of the superconducting gap function occurs deep inside the superconducting state, giving a clear indication of the presence of two distinct superconducting phases with twofold and fourfold symmetries. We infer that the gap functions in both phases have a point node singularity, in contrast to the familiar line node singularity observed in almost all unconventional superconductors.

Journal Article↗
PubMed2003

A mechanism of resistance to TRAIL/Apo2L-induced apoptosis of newly established glioma cell line and sensitisation to TRAIL by genotoxic agents.

Most tumour cells are sensitive to TRAIL-induced apoptosis, but not normal cells; thus, cancer therapy using TRAIL is expected clinically. Several tumour cells are resistant to TRAIL-induced apoptosis, and various mechanisms of such resistance were reported in individual cases. In this study, we established a TRAIL-resistant glioma cell line, which completely lacked TRAIL receptors. In addition, this tumour cell line had wild-type p53 tumour-suppressive gene, suggesting new mechanisms for tumour cells to expand and escape from immune surveillance. The present study further explored the mechanisms that determine the sensitivity to TRAIL. We show that genotoxic agents such as cisplatin, doxorubicin and camptothecin, in addition to UV radiation, can induce TRAIL-R2 on the cell surface of TRAIL receptor-negative tumour cells. Newly synthesised TRAIL-R2 is functional, so apoptosis is effectively induced by TRAIL, but it is significantly inhibited by constitutive expression of dominant-negative p53. In addition, apoptosis induced by pretreatment of genotoxic agents and additional stimulation of TRAIL is efficiently inhibited by either antagonistic anti-TRAIL-R2 antibody or pan-caspase inhibitor z-VAD-FMK. Taken together, these findings suggest that resistance to TRAIL by lack of TRAIL receptors on glioma is restored by genotoxic agents, which support the new strategies for tumour killing by TRAIL-bearing cytotoxic cells in combination with genotoxic treatment.

Antineoplastic Agents↗
PubMed2003

Src family kinase inhibitor PP1 improves motor function by reducing edema after spinal cord contusion in rats.

Following spinal cord injury vascular permeability increases around the area of injury, which possibly leads to secondary tissue damage. Vascular endothelial growth factor (VEGF) and Src which exists downstream of VEGF may contribute to edema formation. We here report that the Src family kinase inhibitor PPI could reduce edema and the inflammatory response after spinal cord injury. In this study we have examined the effect of PPI on motor function after mild spinal cord compression injury. We utilized a mild spinal cord compression model in rats. PPI or vehicle only was administered intraperitoneally after cord compression. The motor function of the hind limbs after injury was categorized into 7 grades. At 1, 3, 7 and 14 days after injury, the spinal cord was removed and the extent of edema formation and inflammation were examined using immunohistochemistry with an anti-IgG and anti-ED-1 antibody. The immunohistochemical analysis revealed that the area of edema formation and inflammation was remarkably reduced in animals with PPI. The muscle function was flaccid in both groups immediately after injury. However, at 3 and 8 days after injury, a significant improvement was observed in the PPI group. These results suggest that PPI is a strong candidate for drug treatment of spinal cord injury.

Animals↗
PubMed2003

Detection of corn intrinsic and recombinant DNA fragments and Cry1Ab protein in the gastrointestinal contents of pigs fed genetically modified corn Bt11.

Genetically modified corn has been approved as an animal feed in several countries, but information about the fate of genetically modified DNA and protein in vivo is insufficient. Genetically modified corn Bt11 is developed by inserting a recombinant DNA sequence encoding insecticidal Cry1Ab protein from Bacillus thuringiensis subsp. kurstaki. We examined the presence of corn intrinsic and recombinant cry1Ab gene by PCR, and the Cry1Ab protein by immunological tests in the gastrointestinal contents of five genetically modified corn Bt11-fed and five nongenetically modified corn-fed pigs. Fragments of corn zein (242 bp), invertase (226 bp) and of ribulose-1,5-bisphosphate carboxylase/ oxygenase genes (1,028 bp) were detected in the gastrointestinal contents of both Bt11 and nongenetically modified corn-fed pigs. Fragments of recombinant cry1Ab gene (110 bp and 437 bp) were detected in the gastrointestinal contents of the Bt11-fed pigs but not in the control pigs. Neither corn intrinsic nor cry1Ab gene fragments were detected in the peripheral blood by PCR. The gastrointestinal contents were positive for Cry1Ab protein by ELISA, immunochromatography, and immunoblot; however, these methods did not work for blood and precluded conclusions about any potential absorption of the protein. These results suggest that ingested corn DNA and Cry1Ab protein were not totally degraded in the gastrointestinal tract, as shown by their presence in a form detectable by PCR or immunological tests.

Animal Feed↗
PubMed2003

Effect of preoperative amino acid infusion on thermoregulatory response during spinal anaesthesia.

BACKGROUND: Intravenous amino acid infusion during general anaesthesia prevents decreases in core temperature resulting from increased energy expenditure and heat accumulation. METHODS: We investigated whether such stimulation also occurs during spinal anaesthesia, which blocks sympathetic nervous activity. We examined the effect of i.v. amino acid infusion on changes in core temperature during spinal anaesthesia. Thirty-five patients were divided into two groups: an i.v. amino acid infusion group (4 kJ kg(-1) h(-1) starting 2 h before surgery); and a saline infusion group. Tympanic membrane core temperature, forearm-fingertip temperature gradient (an index of peripheral vasoconstriction) and mean skin temperature were measured for 90 min after the onset of spinal anaesthesia. RESULTS: Changes in mean arterial pressure and heart rate did not differ significantly between the groups during the study period. Mean final core temperature 90 min after induction of spinal anaesthesia was 35.8 (SEM 0.1) degrees C in the saline group and 36.6 (0.1) degrees C in the amino acid group (P<0.05). The increased level of oxygen consumption in the amino acid group compared with the saline group was preserved even after the onset of spinal anaesthesia. The thermal vasoconstriction threshold, defined as the tympanic membrane temperature that triggered a rapid increase in forearm-fingertip temperature gradient, was increased in the amino acid group [36.8 (0.1) degrees C] compared with the saline group [36.5 (0.1) degrees C] (P<0.05). CONCLUSIONS: Preoperative infusion of amino acids effectively prevents spinal anaesthesia-induced hypothermia by maintaining a higher metabolic rate and increasing the threshold core temperature for thermal vasoconstriction.

Adult↗
PubMed2003

[Metastatic lung tumor: report of two cases].

We herein report 2 cases of metastatic lung tumor. The first case was a 59-year-old female, who had undergone a left radical mastectomy for the treatment of breast cancer 18 years before. She was found to have a pulmonary nodule in the left lower lobe on the routine chest radiograph. She underwent a video-assisted thoracic surgery (VATS) partial resection of the left lower lobe. Tumor was diagnosed as a lung metastasis of the breast cancer microscopically. The second case was a 77-year-old man, who had undergone a right nephrectomy for the treatment of renal cell carcinoma. He was found to have 2 nodules in the right lung (1 in the middle lobe and the other in the lower lobe) on the follow-up computed tomography (CT) scan of the chest. He underwent VATS partial resections of the right middle and lower lobes. While the tumor in the lower lobe was diagnosed as a lung metastasis of the renal cell carcinoma, the tumor in the middle lobe turned out a primary lung cancer.

Adenocarcinoma, Papillary↗
PubMed2003

Detection of Cry1Ab protein in gastrointestinal contents but not visceral organs of genetically modified Bt11-fed calves.

The fate of insecticidal Cry1Ab protein was examined in the gastrointestinal (GI) contents and visceral organs of calves fed insect-resistant genetically modified maize Bt11. Twelve cross-breed (Japanese black x Holstein) calves were fed either Bt11 or non-genetically modified isoline maize for 90 d. Peripheral blood, rumen juice and feces were collected fortnightly, and GI contents and visceral organs were collected at slaughter at the end of the experiment. Samples were checked for Cry1Ab protein by immunological methods, and visceral organs were examined pathologically. Trace amounts of Cry1Ab protein were detected in the GI contents but not in the liver, spleen, kidney, muscle or mesenteric lymph nodes. No lesions were observed pathologically. Cry1Ab protein in the feces was degraded quickly at atmospheric temperature. These results suggested that only a trace amount of Cry1Ab protein survived passage through the GI tract but was not transferred to liver, spleen, kidney, lymph nodes or muscles.

Animals↗
PubMed2003

Detection of genetically modified maize DNA fragments in the intestinal contents of pigs fed StarLink CBH351.

We tried to detect DNA fragments derived from maize in the intestinal contents of pigs fed genetically modified (GM) StarLink CBH351 maize (SL) or non-GM maize. Intestinal contents of 8 SL and 8 non-GM maize-fed pigs were collected at slaughter, and the genes of the recombinant cry9C and the maize intrinsic zein (Zel) were assayed by polymerase chain reaction (PCR) 3 times with a total of 4 primer pairs of different expected lengths. The cry9C gene (either 103 or 170 bp) was detected in the rectal contents (with a frequency of 25-37.5%) and in the cecal contents (25-50%) of the pigs fed SL. In a similar fashion, the zein (Zel) gene (either 242 or 329 bp) was detected in the rectal contents (with a frequency of 31.3%) and in the cecal contents (25-37.5%) of pigs fed on SL non-GM maize. These results suggested that ingested DNA was not totally degraded, but is present in a form detectable by PCR.

Animal Feed↗
PubMed2002

Matrix metalloproteinase-9 and tissue inhibitor of metalloproteinase-1: expression in the lung of fetal rats with nitrofen-induced diaphragmatic hernia.

The surrounding extracellular matrix of airway wall tissues changes in response to mechanical stresses and hypoxia. The presence of matrix metalloproteinase-9 (MMP-9) and its inhibitor, tissue inhibitor of metalloproteinase-1 (TIMP-1), is correlated with collagen degradation and tissue repair in lung disorders. The aim of this study was to evaluate the expression of MMP-9 and TIMP-1 in the lung of fetal rats with nitrofen-induced congenital diaphragmatic hernia (CDH). Administering 100 mg of nitrofen dissolved in 1 ml olive oil to pregnant Wistar rats on day 9 of gestation induced left-sided CDH in fetal rats. In control animals, the same dose of olive oil was given without nitrofen. Cesarean section was performed on day 21 of gestation. The fetuses were divided into two groups: normal controls (n = 10) and nitrofen-induced left-sided CDH (n = 10). Immunoreactivity of the staining for MMP-9 and TIMP-1 in the lung tissues was semiquantitatively analyzed using the staining scores. The relative amount of MMP-9 or TIMP-1 divided by the amount of beta-actin for each lung sample was measured by using the real-time reverse-transcriptase polymerase chain reaction. The immunoreactivity of MMP-9 was significantly increased in the CDH group (n = 5) compared with the control group (n = 5) (p = 0.031). On the other hand, the immunoreactivity of TIMP-1 in the two groups was not significantly different (n = 0.134). The relative amount of MMP-9 (or TIMP-1) in the CDH group (n = 5) does not differ significantly from that in the control group (n = 5) (p = 0.059, 0.596, respectively), but the relative amount of MMP-9 is higher in the CDH group, although it is not significantly higher. On the other hand, the ratios of MMP-9 to TIMP-1 were significantly higher in the CDH group (p = 0.028). In conclusion, fetal rats with nitrofen-induced CDH, a model of respiratory disorders, manifested the excess of MMP-9 activity due to the absence of TIMP-1 that would suggest a trend toward disruption of the extracellular matrix in the CDH lung tissues.

Animals↗
PubMed2002

Effect of muscle length on the recruitment property of single motor units in humans.

In order to examine the effect of muscle length on the recruitment property of a single motor unit (MU), the action potentials of the MU in the human gastrocnemius muscle were recorded during voluntary isometric contraction at different knee joint angles. We found that the recruitment property of MU, which is determined by relationship of recruitment threshold torque (T-th) and ramp contraction speeds, changed as the knee joint angle was changed from 0 degrees to 90 degrees. The decrease of T-th with contraction speed occurred only when the muscle was held long. This result indicates that the MU recruitment property, which decrease of T-th with higher contraction speed, needs both central command and Ia inputs to the alpha-motoneuron.

Action Potentials↗
PubMed2002

Two different inward rectifier K+ channels are effectors for transmitter-induced slow excitation in brain neurons.

Substance P (SP) excites large neurons of the nucleus basalis (NB) by inhibiting an inward rectifier K(+) channel (Kir). The properties of the Kir in NB (KirNB) in comparison with the G protein-coupled Kir (GIRK) were investigated. Single-channel recordings with the cell-attached mode showed constitutively active KirNB channels, which were inhibited by SP. When the recording method was changed from the on-cell to the inside-out mode, the channel activity of KirNB remained intact with its constitutive activity unaltered. Application of Gbeta(1gamma2) to inside-out patches induced activity of a second type of Kir (GIRK). Application of Gbeta(1gamma2), however, did not change the KirNB activity. Sequestering Gbeta(1gamma2) with Galpha(i2) abolished the GIRK activity, whereas the KirNB activity was not affected. The mean open time of KirNB channels (1.1 ms) was almost the same as that of GIRKs. The unitary conductance of KirNB was 23 pS (155 mM [K(+)](o)), whereas that of the GIRK was larger (32-39 pS). The results indicate that KirNB is different from GIRKs and from any of the classical Kirs (IRKs). Whole-cell current recordings revealed that application of muscarine to NB neurons induced a GIRK current, and this GIRK current was also inhibited by SP. Thus, SP inhibits both KirNB and GIRKs. We conclude that the excitatory transmitter SP has two types of Kirs as its effectors: the constitutively active, Gbetagamma-independent KirNB channel and the Gbetagamma-dependent GIRK.

Animals↗