Transient Receptor Potential Ankyrin 1 in Taste Nerve Contributes to the Sense of Sweet Taste in Mice

Transient receptor potential (TRP) channels play a significant role in taste perception. TRP ankyrin 1 (TRPA1) is present in the afferent sensory neurons and is activated by food-derived ingredients, such as Japanese horseradish, cinnamon, and garlic. The present study aimed to investigate the expression of TRPA1 in taste buds, and determine its functional roles in taste perception using TRPA1-deficient mice. In circumvallate papillae, TRPA1 immunoreactivity colocalised with P2X2 receptor-positive taste nerves but not with type II or III taste cell markers. Behavioural studies showed that TRPA1 deficiency significantly reduced sensitivity to sweet and umami tastes, but not to salty, bitter, and sour tastes, compared to that in wild-type animals. Furthermore, administration of the TRPA1 antagonist HC030031 significantly decreased taste preference to sucrose solution compared to that in the vehicle-treated group in the two-bottle preference tests. TRPA1 deficiency did not affect the structure of circumvallate papillae or the expression of type II or III taste cell and taste nerve markers. Adenosine 5'-O-(3-thio)triphosphate evoked inward currents did not differ between P2X2- and P2X2/TRPA1-expressing human embryonic kidney 293T cells. TRPA1-deficient mice had significantly decreased c-fos expression in the nucleus of the solitary tract in the brain stem following sucrose stimulation than wild-type mice. Taken together, the current study suggested that TRPA1 in the taste nerve contributes to the sense of sweet taste in mice.

Effects of laundry-hanging motion on oxygen uptake and ventilation in healthy young women

Many patients with chronic obstructive pulmonary disease (COPD) experience problems during performance of activities of daily living. These problems may lead to reduced physical activity. The purpose of this study was to reveal the influence on the oxygen uptakes in motion methods of hanging on laundry. Eighteen healthy females were recruited for participation in this study. They performed three kinds of movement to hang on laundry. Participants performed the following three actions: (1) hanging some towels on bars with a low stand in a sitting position (Action 1), (2) hanging some towels on bars with a low stand in a standing position (Action 2) and (3) hanging some towels on bars with a high stand in a standing position (Action 3). We measured metabolic and ventilatory requirements during these actions by use of an expires gas analyser. Mutual comparison of the three different types action showed significant differences in the oxygen uptake (VO2), carbon dioxide output (VCO2), minute ventilation (VE), and metabolic equivalents (METs). On the other hands, the differences in respiratory rate (RR) among these three actions were not significant. Action 3 tended to have the most increased values in VO2, VCO2, VE and METs. The Action 1 tended to behave the lowest value. The oxygen uptake and ventilation variables may be influenced by the methods used in hanging laundry.

Ultra-low-loss nanofiber Fabry-Perot cavities optimized for cavity quantum electrodynamics

We demonstrate the fabrication of ultra-low-loss, all-fiber Fabry-Perot cavities that contain a nanofiber section, optimized for cavity quantum electrodynamics. By continuously monitoring the finesse and fiber radius during the fabrication of a nanofiber between two fiber Bragg gratings, we were able to precisely evaluate taper transmission as a function of radius. The resulting cavities have an internal round-trip loss of only 0.31% at a nanofiber waist radius of 207 nm, with a total finesse of 1380, and a maximum expected internal cooperativity of ∼1050 for a cesium atom on the nanofiber surface. Our ability to fabricate such high-finesse nanofiber cavities may open the door for the realization of high-fidelity scalable quantum networks.

Efficacy and safety of osteoporosis medications in a rat model of late-stage chronic kidney disease accompanied by secondary hyperparathyroidism and hyperphosphatemia

This study showed that bisphosphonate was safe and effective for the treatment of bone disorders in stage 4 chronic kidney disease (CKD) rats. Intermittent teriparatide therapy showed an anabolic action on bone even under secondary hyperparathyroidism conditions without having an adverse effect on mineral metabolism in late-stage CKD.

INTRODUCTION

Patients with late-stage CKD are at high risk for fragility fractures. However, there are no consensus on the efficacy and safety of osteoporosis medications for patients with late-stage CKD. In the present study, we aimed to examine the efficacy and safety of alendronate (ALN) and teriparatide (TPD) for treating bone disorder in late-stage CKD with pre-existing secondary hyperparathyroidism using a rat model of CKD.

METHODS

Male 10-week-old Sprague-Dawley rats were subjected to a 5/6 nephrectomy or sham surgery and randomized into the following four groups: sham, vehicle (saline subcutaneous (sc) daily), ALN (50 μg/kg sc daily), and TPD (40 μg/kg sc daily). Medications commenced at 24 weeks of age and continued for 4 weeks. Micro-computed tomography, histological analysis, infrared spectroscopic imaging, and serum assays were performed.

RESULTS

Nephrectomized rats developed hyperphosphatemia, secondary hyperparathyroidism (SHPT), and high creatinine, equivalent to CKD stage 4 in humans. ALN suppressed the bone turnover and increased the degree of mineralization in cortical bone, resulting in an improvement in the mechanical properties. TPD further increased the bone turnover and significantly increased the degree of mineralization, micro-geometry, and bone volume, resulting in a significant improvement in the mechanical properties. Both ALN and TPD had no adverse effect on renal function and mineral metabolism.

CONCLUSIONS

BP is safe and effective for the treatment of bone disorders in stage 4 CKD rats. Intermittent TPD therapy showed an anabolic action on bone even under SHPT conditions without having an adverse effect on mineral metabolism in late-stage CKD.

Autoimmune arthritis deteriorates bone quantity and quality of periarticular bone in a mouse model of rheumatoid arthritis

This study showed that autoimmune arthritis induces especially severe osteoporosis in the periarticular region adjacent to inflamed joints, suggesting that arthritis increases the fragility fracture risk near inflamed joints, which is frequently observed in patients with RA.

INTRODUCTION

Periarticular osteoporosis near inflamed joints is a hallmark of early rheumatoid arthritis (RA). Here we show that rheumatic inflammation deteriorates the bone quality and bone quantity of periarticular bone, thereby decreasing bone strength and toughness in a mouse model of RA.

METHODS

Female BALB/c mice and SKG mice, a mutant mouse model of autoimmune arthritis on the BALB/c background, were used. At 12 weeks of age, BALB/c mice underwent either Sham surgery or bilateral ovariectomy (OVX), and SKG mice underwent intraperitoneal injection of mannan to induce arthritis. Eight weeks later, the mice were killed and the femurs and tibias were subjected to micro-computed tomography, Fourier transform infrared (FTIR) spectroscopic imaging, X-ray diffraction, histology, and mechanical testing.

RESULTS

SKG mice developed significant trabecular bone loss in both the distal metaphysis of the femur and the lumbar vertebral body, but the extent of the bone loss was more severe in the distal metaphysis. Neither SKG nor OVX mice exhibited changes in the geometry and matrix properties of the diaphysis of the femur, whereas SKG mice, but not OVX mice, did exhibit changes in these properties in the distal metaphysis of the femur. Bone strength and fracture toughness of the distal metaphysis of the tibia adjacent to the inflamed ankle joint were significantly decreased in SKG mice.

CONCLUSIONS

Autoimmune arthritis induces periarticular osteoporosis, characterized by deterioration of cortical bone geometry and quality as well as by trabecular bone loss, leading to severe bone fragility in periarticular bone adjacent to inflamed joints.

Occurrence of adverse events caused by valganciclovir as pre-emptive therapy for cytomegalovirus infection after allogeneic stem cell transplantation is reduced by low-dose administration

BACKGROUND

Pre-emptive therapy with valganciclovir (VGCV) has become the standard therapy for preventing cytomegalovirus (CMV) infection after allogeneic hematopoietic stem cell transplantation (HSCT). The effectiveness of low-dose VGCV (900 mg per day) has been shown to be equal to that of standard-dose VGCV (900 mg twice daily); however, individualized optimal dosing and toxicity of VGCV have not been reported.

METHODS

We conducted a retrospective study to evaluate the optimal dose of VGCV as pre-emptive therapy for preventing CMV infection by comparing the frequency of adverse events (AEs) and clinical efficacy in a low-dose VGCV group with those in a standard-dose VGCV group. Thirty-eight patients who were administered VGCV because of CMV antigenemia after HSCT were analyzed.

RESULTS

Neutropenia (standard-dose group: 33%, low-dose group: 15%, P = 0.26) and thrombocytopenia (standard-dose group: 39%, low-dose group: 15%, P = 0.14) were frequent AEs of VGCV, and a significantly higher frequency of overall AEs was detected in the standard-dose group than in the low-dose group (P < 0.01). In comparison of dosage based on weight, dosage of VGCV >27 mg/kg was closely related to onset of AEs (P = 0.04).

CONCLUSIONS

Low-dose VGCV was not inferior in clinical efficacy, including clearance rate of CMV antigenemia and incidence of consequent CMV disease, to standard-dose VGCV as was previously reported. Initial low-dose VGCV for pre-emptive CMV therapy markedly reduces hematologic toxicity and has clinical efficacy equivalent to that of standard-dose VGCV. It is therefore reasonable for patients, except for noticeably overweight patients, to be given initial low-dose VGCV.

Hepatitis B virus (HBV) reverse seroconversion (RS) can be prevented even in non-responders to hepatitis B vaccine after allogeneic stem cell transplantation: long-term analysis of intervention in RS with vaccine for patients with previous HBV infection

BACKGROUND

Reactivation of hepatitis B virus (HBV) infection, reverse seroconversion (RS), is a serious complication after allogeneic stem cell transplantation (alloHSCT). We previously conducted a post-transplant hepatitis B vaccine intervention trial and demonstrated the vaccine efficacy in preventing HBV-RS. This report is an update of the hepatitis B vaccine study.

METHODS

In this trial, 21 patients were enrolled and received a standard 3-dose regimen of hepatitis B vaccine after discontinuation of immunosuppressants, whereas 25 transplant recipients with previous HBV infection did not receive the vaccine and served as controls.

RESULTS

None of the 21 patients in the vaccine group developed HBV-RS and 12 controls developed HBV-RS in median follow-up periods of 60 months (range 13-245). HBV vaccine resulted in a positive value of hepatitis B surface antibody (HBsAb) titer in 9 patients, while HBsAb remained negative in 12 patients. Presence of a high titer of HBsAb before vaccination was associated with conversion into HBsAb positivity after vaccination.

CONCLUSION

These results demonstrated the long-term effects of HBV vaccine for preventing HBV-RS after alloHSCT. Of note, no HBV-RS occurred, even in patients who did not achieve conversion into HBsAb positivity after vaccination.

Anomalous vertebral and posterior communicating arteries as a risk factor in instrumentation of the posterior cervical spine

We investigated the incidence of anomalies in the vertebral arteries and Circle of Willis with three-dimensional CT angiography in 55 consecutive patients who had undergone an instrumented posterior fusion of the cervical spine. We recorded any peri-operative and post-operative complications. The frequency of congenital anomalies was 30.9%, abnormal vertebral artery blood flow was 58.2% and vertebral artery dominance 40%. The posterior communicating artery was occluded on one side in 41.8% of patients and bilaterally in 38.2%. Variations in the vertebral arteries and Circle of Willis were not significantly related to the presence or absence of posterior communicating arteries. Importantly, 18.2% of patients showed characteristic variations in the Circle of Willis with unilateral vertebral artery stenosis or a dominant vertebral artery, indicating that injury may cause lethal complications. One patient had post-operative cerebellar symptoms due to intra-operative injury of the vertebral artery, and one underwent a different surgical procedure because of insufficient collateral circulation. Pre-operative assessment of the vertebral arteries and Circle of Willis is essential if a posterior spinal fusion with instrumentation is to be carried out safely.

Increased risk of bacterial infection after engraftment in patients treated with allogeneic bone marrow transplantation following reduced-intensity conditioning regimen

Although bacterial infection is a major cause of death even after reduced-intensity conditioning (RIC) for allogeneic stem cell transplantation (SCT), little is known about the epidemiology and risk factors. The incidence of bacterial infection in 43 patients who received allogeneic bone marrow transplantation (BMT) using a RIC regimen was compared with that in 68 patients who received BMT using a myeloablative conditioning regimen, and risk factors for bacterial infection were identified. Before engraftment, incidences of febrile neutropenia (FN) and documented infections (DI) were significantly decreased in RIC patients (FN: 59.5% vs. 89.6%, P<0.01, DI: 4.8% vs. 17.9%, P<0.01). However, incidence of bacterial infection was significantly increased in RIC patients in the post-engraftment phase (53.8% vs. 11.1%, log-rank, P<0.01). Blood stream was the most frequent focus of infection in both groups. In multivariate analysis, RIC and acute graft-versus-host disease were revealed to be significant risk factors for bacterial infection in this phase. In summary, risk of bacterial infection after engraftment was significantly higher in RIC patients, although infection was decreased before engraftment, and we need to develop a RIC-specific strategy against bacterial infection after RIC SCT.

Minimally invasive surgical treatment for tuberculous spondylodiscitis

The authors report the cases of 3 patients with tuberculous spondylodiscitis. All patients suffered from severe back or low back pain. Posterolateral endoscopic debridement and irrigation were performed followed by retention of a drainage tube at the affected sites. Additional puncture and drainage were conducted at the same time when extensive cold abscesses were identified around the paravertebral muscle. All patients experienced immediate pain relief postoperatively. This technique is effective for rapid pain relief and in obtaining neurological resolution for patients in the early stages of tuberculous spondylodiscitis and may also be a good method for preventing further vertebral collapse and kyphotic spinal deformity such as Gibbus vertebrae.

Cost benefit and clinical efficacy of low-dose granulocyte colony-stimulating factor after standard chemotherapy in patients with non-Hodgkin's lymphoma

High costs of molecule-targeted drugs, such as rituximab, ibritumomab, and tositumomab have given rise to an economical issue for treating patients with non-Hodgkin's lymphoma (NHL). Granulocyte colony-stimulating factors (G-CSFs), which are also expensive, are widely used for treating neutropenia after chemotherapy. In Japan, lenograstim at 2 microg/kg (about 100 microg/body) or filgrastim at 50 microg/m(2) (about 75 microg/body) is commonly administered for patients with NHL after chemotherapy. Therefore, cost-effectiveness is an important issue in treatment for NHL. Patients with advanced-stage NHL who needed chemotherapy with cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) or a CHOP-like regimen with or without rituximab were enrolled in this randomized cross-over trial to investigate the efficacy and safety of low-dose G-CSF. Half of the patients were administered 75 microg filgrastim in the first course after neutropenia and 50 microg lenograstim in the second course, and the other half were crossed over. Forty-seven patients were enrolled in this cross-over trial, and 24 patients completed the trial. Frequencies and durations of grade 4 leukocytopenia and neutropenia were similar in the two groups. Severe infection was rare and was observed at similar frequency. Frequencies of antibiotics use were also similar. The total cost of G-CSF (cost/drug x duration of administration) was significantly lower in patients who received 50 microg lenograstim. Hence, a low dose of lenograstim might be safe, effective and pharmaco-economically beneficial in patients with advanced-stage NHL.

Behavioral context-dependent modulation of descending statocyst pathways during free walking, as revealed by optical telemetry in crayfish

Crustacean posture control is based on a complex interaction between the statocyst input and other sensory inputs as well as the animal's behavioral context. We examined the effects of behavioral condition on the activity of descending statocyst pathways using an optical telemetry system that allowed underwater recording of neuronal signals from freely behaving crayfish. A functionally identified statocyst-driven interneuron that directionally responded to body tilting without a footboard and to tilting of the footboard was found to show complicated responses depending upon the ongoing behavior of the animal when it freely walked around in water on the aquarium floor. The spike firing frequency of the interneuron increased significantly during walking. When the animal stood or walked on the tilted floor, the interneuron activity represented the tilt angle and direction if the abdomen was actively flexed, but not if it was extended. Two other statocyst-driven descending interneurons were found to be affected differently by the animal's behavioral condition: the spike activity of one interneuron increased during walking, but its directional response on the tilted floor was completely absent during abdominal posture movements, whereas that of another interneuron was enhanced during abdominal extension only, representing the tilt angle and direction. The results obtained in this study provide the first experimental demonstration that crustacean postural control under natural conditions is dependent on very fine aspects of the animal's locomotor behavioral context, suggesting far more complex control mechanisms than those expected from the experimental data obtained in isolated and fixed animals.

Successful treatment with allogeneic peripheral blood stem cell transplantation and granulocyte transfusion for severe aplastic anemia with sinusitis

A 43-year-old woman with severe aplastic anemia (SAA) received anti-thymocyte globulin and cyclosporin A (CyA) and achieved hematological remission. Although she had maintained hematological remission, the disease relapsed 10 months after arbitrary discontinuance of maintenance therapy with CyA. Resumption of CyA therapy was not effective, and her condition became complicated with progressive sinusitis with bone destruction, which was refractory to antibiotics, antifungal agents, granulocyte colony-stimulating factor, and surgical drainage. Because of the necessity for early neutrophil recovery (to resolve the infection), we proceeded with a combination therapy using allogeneic peripheral blood stem cell transplantation (PBSCT) promptly followed by granulocyte transfusion (GTX) from the same human leukocyte antigen-identical donor rather than carrying out a second immunosuppressive therapy. The patient showed temporal resolution of infection on the second day after a single GTX. Although the patient had pneumonia on day 11, it was resolved promptly after engraftment on day 16. This report suggests the clinical utility of a salvage therapy with allogeneic PBSCT followed by GTX in a particular case of recurrent SAA with refractory infections.

Modification of statocyst input to local interneurons by behavioral condition in the crayfish brain

Posture control by statocysts is affected by leg condition in decapod crustaceans. We investigated how, in the crayfish brain, the synaptic response of local interneurons to statocyst stimulation was affected by leg movements on and off a substratum. The magnetic field stimulation method permitted sustained stimulation of statocyst receptors by mimicking body rolling. The statocyst-driven local interneurons were classified into four morphological groups (Type-I-IV). All interneurons except Type-IV projected their dendritic branches to the parolfactory lobe of the deutocerebrum where statocyst afferents project directly. Type-I interneurons having somata in the ventral-paired lateral cluster responded invariably to statocyst stimulation regardless of the leg condition, whereas others having somata in the ventral-unpaired posterior cluster showed response enhancement or suppression, depending on the cell, during leg movements on a substratum, but no response change during free leg movements off the substratum. The synaptic responses of Type-II and IV interneurons were also affected differently by leg movements depending on the substratum condition, whereas those of Type-III remained unaffected. These findings suggest that the statocyst pathway in the crayfish brain is organized in parallel with local circuits that are affected by leg condition and those not affected.

Effects of leg movements on the synaptic activity of descending statocyst interneurons in crayfish, Procambarus clarkii

Crustacean postural control is modulated by behavioral condition. In this study, we investigated how the responses of descending statocyst interneurons were affected during leg movements. Intracellular recording was made from an animal whose statoliths had been replaced with ferrite grains so that statocyst receptors could be activated by magnetic field stimulation. We identified 14 morphological types of statocyst-driven descending interneurons. Statocyst-driven descending interneurons always showed an excitatory response to statocyst stimulation on either ipsilateral or contralateral side to the axon. The response of each statocyst-driven descending interneuron to statocyst stimulation was differently modulated by leg movements in different conditions. During active leg movements, six statocyst-driven descending interneurons were activated regardless of whether a substrate was provided or not. In other two statocyst-driven descending interneurons, the excitatory input during leg movements was stronger when a substrate was provided than when it was not. One statocyst-driven descending interneuron received an excitatory input only during leg movements on a substrate, whereas another statocyst-driven descending interneuron did not receive any input during leg movements both on a substrate and in the air. These results suggest that the descending statocyst pathways are organized in parallel, each cell affected differently by behavioral conditions.

Pneumococcal purulent genual arthritis after allogeneic bone marrow transplantation

A 21-year-old male patient with non-Hodgkin's lymphoma (diffuse large T-cell type, clinical stage IV) received allogeneic bone marrow transplantation (BMT) from a partially HLA-mismatched unrelated donor in July 1998 and achieved complete remission. Thereafter, he suffered from chronic graft-versus-host disease (GVHD) and was continuously administered immunosuppressive drugs for a long time. Two years after the BMT, he complained of severe pain in the right knee, which was swollen, and was diagnosed as having pneumococcal purulent genual arthritis. He underwent arthroscopic synovectomy and was administered systemic and intra-articular antibiotics, leading to a gradual improvement. Streptococcal infections are often seen in patients in the late phase after allogeneic BMT because of immunodeficiency associated with chronic GVHD and hyposplenism. Most streptococcal infections are respiratory tract infections and septicemia, and there have been very few reports on cases of purulent genual arthritis. Administration of prophylactic antibiotics and control of chronic GVHD, which is a risk factor of pneumococcal infection, seem to be important to prevent purulent genual arthritis.

Successful allogeneic bone marrow transplantation from an HBV-positive donor into an HBV-positive recipient using lamivudine

A 21-year-old woman with severe aplastic anemia underwent allogeneic bone marrow transplantation from an HLA-identical sibling donor. The patient also had chronic hepatitis B and the donor was an HBV carrier. To decrease HBV and improve hepatic dysfunction before BMT, the patient had received lamivudine for 6 months. After marrow transfusion, administration of lamivudine was continued to inhibit replication of donor-derived HBV. The patient showed hematological engraftment on day 13 without any serious liver dysfunction. Eight months after BMT, she is now alive and well without chronic liver GVHD or reactivation of hepatitis B. HBV-DNA was not detected in the patient's serum. Administration of lamivudine to a BMT recipient with chronic hepatitis B may be a safe and promising way to prevent fatal liver dysfunction in the setting of allogeneic BMT, even in the event of BMT from an HBV-positive donor.

Cyclosporin A-induced encephalopathy after allogeneic bone marrow transplantation with prevention of graft-versus-host disease by tacrolimus

A 21-year-old woman with severe aplastic anemia received an allogeneic bone marrow transplant (allo-BMT) from an HLA-matched and ABO-matched sibling donor after conditioning with cyclophosphamide, rabbit ATG (Lymphoglobuline; Aventis-Pharma), and total lymphoid irradiation. She had a long history of cyclosporin A (CsA) therapy before conditioning. She complained of severe headache and convulsions on day 0, and findings on magnetic resonance images suggested CsA-induced encephalopathy. CsA was immediately stopped, and tacrolimus for prevention of graft-versus-host disease (GVHD) was started on day 2. Hematological engraftment was observed on day 14 without serious GVHD. Prompt diagnosis, replacement of immunosuppressive agents, and careful monitoring of serum drug concentrations are thought to have contributed to the patient's good clinical course, since CsA-induced encephalopathy tends to be recurrent but to improve completely without any sequelae.

Quantitative analyses of anatomical and electrotonic structures of local spiking interneurons by three-dimensional morphometry in crayfish

We quantitatively investigated the three-dimensional structure of the dendrites of local spiking interneurons using a confocal laser scanning microscope in the terminal abdominal ganglion of crayfish. We also studied their passive membrane properties electrophysiologically using the single-electrode current clamp techniques to analyze their electrotonic structure. All of the local spiking interneurons examined in this study lacked distinctive axonal structure and had a monopolar cell body that was connected with a fine primary process to a thick main segment. Numerous fine secondary processes projected from the main segment in the ganglionic neuropile. The average anatomical length of a secondary process from the main segment to its terminal was 261.9 +/- 15.2 microm. The average input resistance and membrane time constant of local spiking interneurons, obtained from their voltage responses to intracellular injection of step current pulses in the main segment, were 15.2 +/- 1.6 MOmega and 13.9 +/- 1.9 msec, respectively. Calculation of the electrotonic length of dendritic processes based on morphological and physiological data obtained in this study revealed that the average electrotonic length of secondary processes in local spiking interneurons was significantly longer than in local nonspiking interneurons, although both types of local interneurons showed apparently similar anaxonic structure. The steady-state voltage attenuation factors for the secondary processes of local spiking interneurons were significantly greater than those of local nonspiking interneurons in both centrifugal and centripetal directions. The larger electrotonic structure of local spiking interneurons compared to that of nonspiking interneurons appears to be compensated for by their excitable dendritic membrane.

In vitro and in vivo efficacies of T-3811ME (BMS-284756) against Mycoplasma pneumoniae

T-3811, the free base of T-3811ME (BMS-284756), a new des-F(6)-quinolone, showed a potent in vitro activity (MIC at which 90% of the isolates tested are inhibited [MIC(90)], 0.0313 microg/ml) against Mycoplasma pneumoniae. The MIC(90) of T-3811 was 4-fold higher than that of clarithromycin but was 4- to 8-fold lower than those of trovafloxacin, gatifloxacin, gemifloxacin, and moxifloxacin and was 16- to 32-fold lower than those of levofloxacin, ciprofloxacin, and minocycline. In an experimental M. pneumoniae pneumonia model in hamsters, after the administration of T-3811ME (20 mg/kg of body weight as T-3811, once daily, orally) for 5 days, the reduction of viable cells of M. pneumoniae in bronchoalveolar lavage fluid was greater than those of trovafloxacin, levofloxacin, and clarithromycin (20 and 40 mg/kg, orally) (P < 0.05).

Modulatory effects of nitric oxide on synaptic depression in the crayfish neuromuscular system

A characteristic physiological property of the neuromuscular junction between giant motor neurones (MoGs) and fast flexor muscles in crayfish is synaptic depression, in which repetitive electrical stimulation of the MoG results in a progressive decrease in excitatory junction potential (EJP) amplitude in flexor muscle fibres. Previous studies have demonstrated that l-arginine (l-Arg) modulates neuromuscular transmission. Since l-Arg is a precursor of nitric oxide (NO), we examined the possibility that NO may be involved in modulating neuromuscular transmission from MoGs to abdominal fast flexor muscles. The effect of a NO-generating compound, NOC7, was similar to that of l-Arg, reversibly decreasing the EJP amplitude mediated by the MoG. While NOC7 reduced the amplitude of the EJP, it induced no significant change in synaptic depression. In contrast, a scavenger of free radical NO, carboxy-PTIO, and an inhibitor of nitric oxide synthase, l-NAME, reversibly increased the EJP amplitude mediated by MoGs. Synaptic depression mediated by repetitive stimulation of MoGs at 1 Hz was partially blocked by bath application of l-NAME. Bath application of a NO scavenger, a NOS inhibitor and NO-generating compounds had no significant effects on the depolarisation of the muscle fibres evoked by local application of l-glutamate. The opposing effects on EJP amplitude of NOC7 and of carboxy-PTIO and l-NAME suggest that endogenous NO presynaptically modulates neuromuscular transmission and that it could play a prominent role at nerve terminals in eliciting MoG-mediated synaptic depression in the crayfish Procambarus clarkii.

Information processing by nonspiking interneurons: passive and active properties of dendritic membrane determine synaptic integration

Nonspiking interneurons control activities of postsynaptic cells without generating action potentials in the central nervous system of many invertebrates. Physiological characteristics of their dendritic membrane have been analyzed in previous studies using single electrode current- and voltage-clamp techniques. We constructed a single compartment model of an identified nonspiking interneuron of crayfish. Experimental results allowed us to simulate how the passive and active properties of the dendritic membrane influence the integrative processing of synaptic inputs. The results showed that not only the peak amplitude but also the time course of synaptic potentials were dependent on the membrane potential level at which the synaptic activity was evoked. When the synaptic input came sequentially, each individual input was still discernible at depolarized levels at which the membrane time constant was short due to depolarization-dependent membrane conductances. In contrast, synaptic potentials merged with each other to develop a sustained potential at hyperpolarized levels where the membrane behaved passively. Thus, synaptic integration in a single nonspiking interneuron depends on the value of membrane potential at which it occurs. This probably reflects the temporal resolution required for specific types of information processing.

Electrophysiological and theoretical analysis of depolarization-dependent outward currents in the dendritic membrane of an identified nonspiking interneuron in crayfish

Depolarization-dependent outward currents were analyzed using the single-electrode voltage clamp technique in the dendritic membrane of an identified nonspiking interneuron (LDS interneuron) in situ in the terminal abdominal ganglion of crayfish. When the membrane was depolarized by more than 20 mV from the resting potential (65.0 +/- 5.7 mV), a transient outward current was observed to be followed by a sustained outward current. Pharmacological experiments revealed that these outward currents were composed of 3 distinct components. A sustained component (I(s)) was activated slowly (half rise time > 5 msec) and blocked by 20 mM TEA. A transient component (I(t1)) that was activated and inactivated very rapidly (peak time < 2.5 msec, half decay time < 1.2 msec) was also blocked by 20 mM TEA. Another transient component (I(t2)) was blocked by 100 microM 4AP, activated rapidly (peak time < 10.0 msec) and inactivated slowly (half decay time > 131.8 msec). Two-step pulse experiments have revealed that both sustained and transient components are not inactivated at the resting potential: the half-maximal inactivation was attained at -21.0 mV in I(t1), and -38.0 mV in I(t2). I(s) showed no noticeable inactivation. When the membrane was initially held at the resting potential level and clamped to varying potential levels, the half-maximal activation was attained at -36.0 mV in I(s), -31.0 mV in I(t1) and -40.0 mV in I(t2). The activation and inactivation time constants were both voltage dependent. A mathematical model of the LDS interneuron was constructed based on the present electrophysiological records to simulate the dynamic interaction of outward currents during membrane depolarization. The results suggest that those membrane conductances found in this study underlie the outward rectification of the interneuron membrane as well as depolarization-dependent shaping of the excitatory synaptic potential observed in current-clamp experiments.

[Nephrotoxicity of piperacillin combined with furosemide in rats]

Nephrotoxicity of piperacillin (PIPC) was evaluated in rats after combined administration with furosemide. After intravenous administration of PIPC (1600 mg/kg), the rats showed no change in urinalysis, biochemical analysis of plasma and histopathological analysis. The rats receiving furosemide (100 mg/kg) showed elevation of urinary NAG, BUN and creatinine concentrations, and showed slight degeneration of the renal proximal tubules. The rats receiving PIPC (1600 mg/kg) and furosemide (100 mg/kg) showed elevation of BUN and creatinine concentrations, and showed slight degeneration of the proximal tubules. These changes were comparable to those in rats receiving furosemide alone. The rats receiving cephaloridine (1600 mg/kg) showed elevation of urinary protein, BUN and creatinine concentrations, and showed moderate degeneration and necrosis of the proximal tubules. The nephrotoxicity was enhanced by combination with furosemide. In conclusion, no enhanced effect of nephrotoxicity was observed by combination of PIPC with furosemide.

[In vitro interaction of piperacillin and imipenem/cilastatin combined with aminoglycosides against Pseudomonas aeruginosa]

The in vitro interactions of piperacillin (PIPC) and imipenem/cilastatin (IPM/CS) combined with 5 kinds of aminoglycosides (gentamicin, tobramycin, amikacin (AMK), isepamicin and netilmicin) were investigated against IPM/CS-susceptible (MIC of IPM/CS was < or = 3.13 micrograms/ml) and IPM/CS-resistant (MIC of IPM/CS was > or = 12.5 micrograms/ml) Pseudomonas aeruginosa. The following results were obtained. 1. In the checkerboard dilution studies, the combinations of PIPC with aminoglycosides showed synergistic effect for more than 50% of the each 54 strains of IPM/CS-susceptible and IPM/CS-resistant P. aeruginosa. The synergistic/additive effects of PIPC with aminoglycosides were demonstrated for all tested strains. 2. In the checkerboard dilution studies, the combinations of IPM/CS with aminoglycosides showed no antagonism against any strains. The synergistic effects of IPM/CS with aminoglycosides were demonstrated for 0 to 14.8%, and these values were smaller than the combinations of PIPC with aminoglycosides. 3. Corresponding to the results of checkerboard dilution studies, the combination of PIPC with AMK was more effective than the combination of IPM/CS with AMK on the killing curve for IPM-resistant P. aeruginosa. In conclusion, PIPC showed the synergistic effects in combinations with aminoglycosides against IPM/CS-resistant P. aeruginosa. These results suggest that the combination therapies of PIPC with aminoglycosides are useful for the clinical treatment of serious infections due to P. aeruginosa.

In vitro and in vivo antimicrobial activities of T-3811ME, a novel des-F(6)-quinolone

The in vitro and in vivo activities of T-3811ME, a novel des-F(6)-quinolone, were evaluated in comparison with those of some fluoroquinolones, including a newly developed one, trovafloxacin. T-3811, a free base of T-3811ME, showed a wide range of antimicrobial spectra, including activities against Chlamydia trachomatis, Mycoplasma pneumoniae, and Mycobacterium tuberculosis. In particular, T-3811 exhibited potent activity against various gram-positive cocci, with MICs at which 90% of the isolates are inhibited (MIC90s) of 0.025 to 6.25 microgram/ml. T-3811 was the most active agent against methicillin-resistant Staphylococcus aureus and streptococci, including penicillin-resistant Streptococcus pneumoniae (PRSP). T-3811 also showed potent activity against quinolone-resistant gram-positive cocci with GyrA and ParC (GrlA) mutations. The activity of T-3811 against members of the family Enterobacteriaceae and nonfermentative gram-negative rods was comparable to that of trovafloxacin. In common with other fluoroquinolones, T-3811 was highly active against Haemophilus influenzae, Moraxella catarrhalis, and Legionella sp., with MIC90s of 0.0125 to 0.1 microgram/ml. T-3811 showed a potent activity against anaerobic bacteria, such as Bacteroides fragilis and Clostridium difficile. T-3811 was the most active agent against C. trachomatis (MIC, 0.008 microgram/ml) and M. pneumoniae (MIC90, 0.0313 microgram/ml). The activity of T-3811 against M. tuberculosis (MIC90, 0.0625 microgram/ml) was potent and superior to that of trovafloxacin. In experimental systemic infection with a GrlA mutant of S. aureus and experimental pneumonia with PRSP in mice, T-3811ME showed excellent therapeutic efficacy in oral and subcutaneous administrations.

Neuronal mechanisms underlying the facilitatory control of uropod steering behaviour during treadmill walking in crayfish. II. Modulation Of uropod motoneurone excitation by leg proprioception

The synaptic activities underlying the uropod steering behaviour of crayfish evoked by tilting the substratum beneath the legs have been studied intracellularly in unanaesthetized animals standing or walking on a treadmill. The uropod motoneurones showed little or no synaptic response when the treadmill was tilted while the animal was in a quiescent state and the membrane potential was at its resting value. When the same stimulus was given while the animal was walking or in an active stance on the treadmill, the motoneurones showed transient much-enhanced excitatory or inhibitory responses to tilt, depending on the tilt direction. These responses were superimposed on a sustained level of background excitation so that the spike activity of the motoneurones either increased or decreased. Premotor nonspiking interneurones also showed little or no synaptic response to the tilt stimulus while the animal was resting, but greatly enhanced responses, in either a depolarizing or a hyperpolarizing direction, while the animal was walking or in the active-standing state. The results indicate that the proprioceptor inputs converging onto the uropod motoneurones, either directly or through premotor nonspiking interneurones, are gated not only in the uropod motor system in the terminal abdominal ganglion but also at as yet unidentified sites upstream in anterior ganglia, thus suggesting multiple gate control of the descending proprioceptor pathway.

Neuronal mechanisms underlying the facilitatory control of uropod steering behaviour during treadmill walking in crayfish. I. Antagonistically regulated background excitability of uropod motoneurones

One of the postural reflexes of crayfish, the uropod steering response, is elicited by specific sensory inputs while the animal is walking. It is not elicited, however, by the same inputs when the animal is at rest. To clarify the neuronal mechanisms underlying this facilitatory control of body posture in the active animals, we used intracellular recordings to analyse the synaptic activities of uropod motor system neurones in an unanaesthetized whole-animal preparation. Several uropod motoneurones were found to receive sustained depolarizing inputs during walking, whereas the walking leg motoneurones sampled always showed rhythmic activity. The membrane conductance of the uropod motoneurones increased during the sustained synaptic activity. Premotor nonspiking interneurones showed depolarizing or hyperpolarizing membrane potential changes during walking that were also accompanied by increases in membrane conductance. Some of these interneurones enhanced uropod motoneurone activity, whereas others suppressed it during walking. These results suggest that the background excitability of uropod motoneurones is kept at an intermediate level during walking by the antagonistic inputs from premotor nonspiking interneurones so that the uropod motor system can be responsive to both further excitatory and inhibitory inputs resulting from postural changes. &lt;P&gt;

Quantitative analyses of anatomical and electrotonic structures of crayfish nonspiking interneurons by three-dimensional morphometry

The three-dimensional structure of premotor nonspiking interneurons in the terminal abdominal ganglion of crayfish have been studied quantitatively by using a confocal laser-scanning microscope. Their passive membrane properties have also been studied electrophysiologically to analyze their electrotonic structure. In either one of the two major morphological types, anterolateral (AL) and posterolateral (PL), that are characterized by different locations of cell bodies in the ganglion, the monopolar cell body is connected with a fine primary process to a thick main segment projecting numerous fine secondary processes. These two types of cells share a common dendritic field in the neuropil, showing similar anatomical characteristics of dendrites. Electrotonic analyses based on the present anatomical and physiological measurements have revealed that the steady-state voltage-attenuation factors for the secondary processes were not statistically different between the AL- and PL-type cells. Comparison between the premotor nonspiking interneurons and an identified sensory nonspiking interneuron, which was studied previously, has revealed that voltage attenuation over secondary processes in both the centripetal and the centrifugal directions was significantly greater in the sensory than in the premotor interneurons, although the anatomical length of each secondary process from its terminal to the main segment was not different between them. Differences in the electrotonic structure between sensory and premotor nonspiking interneurons indicate their different modes of synaptic integration in the control of postsynaptic nerve cells.

Quinolone susceptibility of norA-disrupted Staphylococcus aureus

The MIC of norfloxacin for the norA-disrupted mutant termed RDN1, obtained from quinolone-susceptible Staphylococcus aureus RN4220, was eightfold lower than that for RN4220. The increase in susceptibility was related to an increase of drug accumulation by RDN1. These results indicate that NorA plays an important role in the susceptibility of quinolone-susceptible S. aureus to selected quinolones.

Antibacterial activity of quinolones against coagulase-negative staphylococci and the quinolone resistance-determining region of the gyrA genes from six species

Antibacterial activity of quinolones against three species of coagulase-negative staphylococci was investigated. Tosufloxacin and sparfloxacin exhibited potent activities against Staphylococcus epidermidis, Staphylococcus haemolyticus and Staphylococcus saprophyticus compared with other quinolones tested. From the analysis of the DNA sequence in the quinolone resistance-determining region (QRDR), greater than 80% homology was recognized in coagulase-negative staphylococci. A series residue was conserved in all six species at the position corresponding to position 84 in Staphylococcus aureus.

Antibacterial activities of tosufloxacin against anaerobic bacteria and the electron micrograph of its bactericidal effects

Tosufloxacin, a quinolone, showed a broad antibacterial spectrum against gram-positive and gram-negative bacteria including anaerobic bacteria. Tosufloxacin was 4- to 8-fold more active than levofloxacin and ciprofloxacin. The MIC90 of tosufloxacin for clinical isolates of Bacteroides fragilis, Bacteroides vulgatus, Bacteroides thetaiotaomicron and Peptostreptococcus asaccharolyticus were 0.78, 0.39, 1.56 and 0.39 micrograms/ml, respectively. Morphological observation with the scanning and transmission electron microscope revealed that exposure of B. fragilis ATCC 25285 to tosufloxacin resulted in the formation of filamentous cells with mesosome-like structures. Tosufloxacin also induced the mini-cell resulting from the unusual cell division system and a number of holes in the outer membrane. Tosufloxacin at 4 MIC caused some change in cell wall organization and cell lysis. After exposure of P. asaccharolyticus ATCC 14953 to tosufloxacin, the cells increased considerably in size and the cell wall and cross wall thickening was observed.

Two types of identified ascending interneurons with distinct GABA receptors in the crayfish terminal abdominal ganglion

More than half of the identified ascending interneurons originating in the terminal abdominal ganglion of the crayfish received inhibitory sensory inputs from hair afferents innervating the tailfan on the side contralateral to their main branches. Biochemical aspects of this transverse lateral inhibition of ascending interneurons were examined by the use of neurophysiological and pharmacological techniques. Local application of gamma-aminobutyric acid (GABA) and its agonist muscimol into the neuropil induced membrane hyperpolarization of identified ascending interneurons with an increase in membrane conductance. Because the reversal potential of inhibitory postsynaptic potential (IPSPs) in ascending interneurons elicited by the sensory stimulation and GABA injection was similar, and the sensory-stimulated IPSPs of the interneurons were blocked by GABA and muscimol application, this study strongly suggests a GABAergic nature for transverse lateral inhibition of ascending interneurons. According to the response to the GABAA antagonists bicuculline and picrotoxin, ascending interneurons were classified into two types, picrotoxin-sensitive and picrotoxin-insensitive interneurons. Identified ascending interneurons VE-1 and RO-4 showed a pharmacological profile similar to that of the classical GABAA receptor of the vertebrates. Bath application of both bicuculline and picrotoxin reversibly reduced the amplitudes of IPSPs. The other identified ascending interneurons CA-1, RO-1, and RO-2 were not affected significantly by the bath application of GABAA and GABAB antagonists, although bath application of low-chloride saline reversed the sensory-stimulated IPSPs. IPSPs of the picrotoxin-sensitive interneurons had a rather faster time course and shorter duration in comparison with those of the picrotoxin-insensitive interneurons.

Mutations in the gyrA and grlA genes of quinolone-resistant clinical isolates of methicillin-resistant Staphylococcus aureus

The mutations in the quinolone-resistance determining regions (QRDR) of the gyrA, gyrB and grlA genes and in the norA gene from five clinical isolates of methicillin resistant Staphylococcus aureus (MRSA) were examined by DNA sequencing. The mutation from Ser84 to Leu in GyrA was associated with relatively high-level resistance to quinolones, whereas the mutation from Glu88 to Gly or Lys in GyrA was associated with low-level resistance to quinolones. Mutations of the grlA gene were observed at codon 80 (Ser80) or 84 (Glu84), independent of the mutations of gyrA. No mutations were observed in either the gyrB or norA genes.

Sensory control mechanisms of the uropod equilibrium reflex during walking in the crayfish Procambarus clarkii

The temporal characteristics of statocyst and leg proprioceptive inputs to the uropod motor system were investigated in crayfish using behavioural and electromyographic analyses to elucidate their functional roles in the control of the uropod steering response under natural conditions. When the animal, which was suspended in the air without a footboard, was actively extending its abdomen, prolonged stimulation of the statocysts by body rolling elicited a maintained asymmetrical configuration of the bilateral uropods. Prolonged stimulation of the walking legs by footboard tilting with the animal body held in the upright position elicited a transient uropod response. When the treadmill was tilted while the animal was walking on it in the upright position, the uropods showed the same transient response. However, when the animal body was rolled, together with the treadmill, while the animal was walking on it, the uropods showed a transient response which was reversed in direction compared with that observed during body rolling without a footboard. This transient response was abolished by the removal of the statoliths. The results show that the statocysts and leg proprioceptors exert sustained and transient control effects, respectively, on the uropod motor system during walking. It is also suggested that the uropod response to body rolling during walking is controlled primarily by leg proprioceptor signals which result from statocyst-induced changes in the leg position.

Regional characteristics of the membrane response of an identified crayfish nonspiking interneuron to intracellularly injected current

1. We investigated the membrane response of the local directionally selective (LDS) interneuron, a nonspiking cell identified in the terminal abdominal ganglion of crayfish, to intracellularly injected current in different regions within the cell by single-electrode, discrete current-clamp experiments. The site of electrode impalement into the cell was visualized in situ together with the cell structure under a dissecting microscope. 2. The LDS interneuron has dendritic branches on both hemiganglia connected by a thick segment crossing the midline. Irrespective of the site of electrode impalement, the interneuron showed outward rectification upon depolarization from the resting potential level. When hyperpolarizing current was injected, a linear relationship was observed between the voltage response of the interneuron and the amount of injected current. Upon large hyperpolarization, however, the interneuron showed inward rectification. 3. The input resistance of the interneuron measured within the linear range of the membrane response was significantly lower in the transverse segment than in lateral dendrites (0.001 < P < 0.01). The time constant of the transient voltage response to step current injection was also significantly shorter in the transverse segment than in the lateral dendrites (0.001 < P < 0.01). 4. Although the regional difference in the input resistance could be accounted for, at least partly, by different geometric conditions of each dendritic branch into which current was injected, the regional difference in the time constant of the membrane response cannot be accounted for by structural differences because the time constant is independent of the membrane area. It is thus suggested that the passive properties of the interneuron membrane that are related to its response time constant show regional variability within the cell.

DNA gyrase gyrA mutations in quinolone-resistant clinical isolates of Pseudomonas aeruginosa

The mutations in the quinolone resistance-determining region of the gyrA gene from clinical isolates of Pseudomonas aeruginosa were determined by DNA sequencing. The strains were isolated in 1989 and 1993. No mutations were detected in the clinical isolates in 1989, while five types of mutations were identified in the isolates in 1993. These mutations were as follows: group 1, a Thr residue to an Ile residue at position 83 (Thr-83-Ile); group 2, Asp-87-Asn; group 3, Thr-83-Ile and Asp-87-Gly; group 4, Thr-83-Ile and Asp-87-Asn; group 5, Thr-83-Ile and Asp-87-His. Three types of double mutations (groups 3, 4, and 5) have not been described previously. These mutations were homologous to the Ser-83-Leu, Asp-87-Asn, and Asp-87-Gly changes observed in Escherichia coli. Thus, DNA gyrase A subunit mutations are implicated in resistance to quinolones in P. aeruginosa as well as E. coli.

[Formation of experimental rat bladder calculus and adherence of Pseudomonas aeruginosa to the calculus]

The formation of experimental bladder calculus was studied. The calculus was formed by the uptake of ethylene glycolwater (1%) and retaining the silk thread in rat bladder with high frequency. The components of the calculus were calcium oxalate and calcium phosphate from the results of the electron prove micro analysis (EPMA) and ion chromatography. On the 7th day after the beginning of experiment, Pseudomonas aeruginosa was inoculated to the rat bladder via the urethra. Seven days after the infection, P. aeruginosa adhered to the surface of the calculus such as an aspect of a biofilm. It was considered that this experimental model was useful to study the adherence of bacteria, biofilm formation and its chemotherapy by antibacterial agents.

Analysis of the NH2-terminal 87th amino acid of Escherichia coli GyrA in quinolone-resistance

The functional contributions of amino acid residue Asp87 of Escherichia coli gyrase A protein (GyrA) was analyzed by site-directed mutagenesis. We generated a series of mutants, in which Asp87 of GyrA was changed to Ala, Val, Phe, Asn, Ser, and Lys. By genetic analysis of gyrA genes in a gyrA temperature-sensitive (Ts) background, it was shown that all these mutations caused the quinolone-resistance. These results indicate that the 87th amino acid of E. coli GyrA must have negative charge in expressing the phenotype of quinolone sensitivity. These findings also suggest that the carboxyl group of Asp87 may interact with quinolone drugs.

[Absorption, distribution, metabolism and excretion of T-3761, a new quinolone derivative, in experimental animals]

We studied the absorption, distribution, metabolism and excretion of T-3761, a new quinolone derivative, in experimental animals. The following results were obtained. 1. The peak serum levels of T-3761 after a single oral administration to various fasting animals at a dose of 5 mg/kg were high in the order of rats, dogs, mice and rabbits, showing favorable absorption in all animals except for rabbits. In mice and rats, T-3761 showed higher peak serum levels than ofloxacin and ciprofloxacin but T-3761 were more rapidly eliminated from serum than ofloxacin and ciprofloxacin. 2. Tissue concentrations of T-3761 in rats were similar to those of ofloxacin but its ratio of tissue to serum levels were lower than those of ofloxacin. 3. Urinary excretion of T-3761 as active form until 24 hours after oral administration was 27.3%, 63.1%, 41.0% and 63.3% in mice, rats, rabbits and dogs, respectively. Only unchanged T-3761 was detected as active form in urine of all animals tested. In rats, urinary concentrations until 2 hours after administration were higher than those of ofloxacin. 4. Biliary excretion of T-3761 in mice and rats were 2.9% and 1.4% as active form. 5. The absorption of T-3761 was not different in male and female rats or 8 and 14 weeks old rats. The meal lowered absorption of T-3761 in rats. There was no significant difference in serum levels, urinary excretion and distribution to tissues after multiple administration of T-3761 comparing with its single administration. 6. In rats with liver dysfunction induced by D-galactosamine, the serum levels and urinary excretion were slightly higher than in normal rats. On the other hands, in rats with kidney dysfunction induced by HgCl2, the serum levels were significantly higher and urinary excretion of T-3761 was significantly lower than in normal rats. Above results show that T-3761 has unique characteristics in absorption, excretion and distribution after oral administration to animals among new quinolones, i.e., T-3761 was eliminated rapidly and poorly distributed to tissues but showed superior absorption and high peak serum levels.

[Mechanism of renal excretion of T-3761, a novel fluoroquinolone agent, in rabbits]

The mechanism of the renal excretion of T-3761, a novel oral fluoroquinolone agent, was studied by renal clearance, stop-flow techniques and analyzing the pharmacokinetics with and without probenecid in rabbits, and which were compared with those of ofloxacin (OFLX). In rabbits probenecid treatment induced increases in the elimination half-life (2.1 times higher) and area under the serum concentration-time curve (3.1 times), and decreases in elimination rate constant (0.44 times) and total body clearance (0.35 times), while volume of distribution showed no significant change. In the stop-flow pattern, a specific peak of T-3761 was observed. On the other hand, a peak of OFLX was observed at the peak of PAH and a small trough at the trough of sodium. And the renal clearance of T-3761 and OFLX were about 4.9 and 3.3 times higher than the corresponding Clcr, respectively. These results suggested that T-3761 was excreted into urine by both glomerular filtration and renal tubular secretion, and was scarcely reabsorbed at distal tubule. The short elimination half-life of T-3761 might be explained by its great ratio of tubular excretion.

Analysis of the NH2-terminal 83rd amino acid of Escherichia coli GyrA in quinolone-resistance

Artificial mutations of Gyrase A protein (GyrA) in Escherichia coli by site-directed mutagenesis were generated to analyze quinolone-resistant mechanisms. By genetic analysis of gyrA genes in a gyrA temperature sensitive (Ts) background, exchange of Ser at the NH2-terminal 83rd position of GyrA to Trp, Leu, Phe, Tyr, Ala, Val, and Ile caused bacterial resistance to the quinolones, while exchange to Gly, Asn, Lys, Arg and Asp did not confer resistance. These results indicate that it is the most important for the 83rd amino acid residue to be hydrophobic in expressing the phenotype of resistance to the quinolones. These findings also suggest that the hydroxyl group of Ser would not play a major role in the quinolone-gyrase interaction and Ser83 would not interact directly with other amino acid residues.