ABSTRACT
The potential value of hypervascularity detected with power Doppler ultrasonography (PDU) within equine superficial digital flexor tendon (SDFT) as a prognostic factor of SDFT injury is not clear. The purpose of this study was to test the hypothesis that hypervascularity within SDFT is one of the risk factors for subsequent severe SDFT injury and to evaluate the prognostic value. A prospective cohort study of 97 Thoroughbred racehorses without any clinical signs of SDFT injury was conducted. Six variables of age, body weight, sex, the cross-sectional area of SDFT, PDU signal within SDFT and experience of steeplechase were assessed for the possibility of risk factors of subsequent SDFT injury in follow-up period of 1 year. Multivariable logistic regression analyses were used for assessment of the odds ratios (ORs) and 95â¯% confidence intervals (CIs) of SDFT injury. Multivariable logistic regression analysis revealed that the PDU signal within SDFT was a risk factor for the development of SDFT injury in follow-up period (P = 0.017). The adjusted OR of SDFT injury was significantly higher in PDU positive group than in PDU negative group (OR 3.17, 95â¯% CIs 1.20-8.35). Although further studies are required, these results would be useful for early detection and/or prevention of development for clinical severe SDFT injury.
Subject(s)
Horse Diseases , Tendon Injuries , Ultrasonography, Doppler , Animals , Horses/injuries , Male , Female , Tendon Injuries/veterinary , Tendon Injuries/diagnostic imaging , Ultrasonography, Doppler/veterinary , Prognosis , Prospective Studies , Horse Diseases/diagnostic imaging , Risk Factors , Forelimb/diagnostic imaging , Forelimb/injuries , Cohort StudiesABSTRACT
OBJECTIVE: The N-methyl-D-aspartate receptor subunit 2B (GluN2B) is involved in regulation of anxiety and depression and nervous activity in the brain. Single nucleotide polymorphisms of the GluN2B gene (GRIN2B) are associated with human mental function and behaviour. We investigated whether four GRIN2B polymorphisms (rs7301328, rs1806201, rs1805247, and rs1805502) affect characterisation of personality traits. METHODS: In 248 young people, GRIN2B polymorphisms were analysed, and personality traits were assessed using the Neuroticism Extraversion Openness-Five Factor Inventory (NEO-FFI) and State-Trait Anxiety Inventory (STAI). RESULTS: There was no main effect of the GRIN2B polymorphisms on the NEO-FFI and STAI dimension scores. Interaction between polymorphism and sex was found in rs1805247 (p = 0.034) and rs1805502 (p = 0.040) in terms of the conscientiousness score of the NEO-FFI. However, post hoc simple main effect analysis showed no significant effect. The preliminary haplotype analysis indicated that haplotype CTT (rs1806201-rs1805247-rs1805502) in the haplotype block was associated with the extraversion score of the NEO-FFI in female participants (p = 0.044), but the significance was lost on correction for multiple testing. CONCLUSION: There was no significant association between selected GRIN2B polymorphisms and personality traits, but this may be due to low statistical power. Further studies involving a larger study population are needed to clarify this.
Subject(s)
Asian People/genetics , Personality/genetics , Polymorphism, Single Nucleotide , Receptors, N-Methyl-D-Aspartate/genetics , Female , Gene Frequency , Haplotypes , Humans , Japan , Male , Personality Inventory , Young AdultABSTRACT
A retrospective cohort study was conducted to investigate risk factors for the failure of Thoroughbred racehorses to return to racing after an injury of the superficial digital flexor tendon (SDFT). Successful return was defined as the completion of five or more races after SDFT injury. The official Japan Racing Association (JRA) medical records of racehorses with a core-type SDFT injury were reviewed for clinical variables related to the characteristics of the horse and the severity of SDFT injuries at the time of diagnosis. Data on racing outcomes were obtained from the official JRA racing database. Risk factors were screened using univariable logistic regression and subsequent multivariable model building. Forty-nine of 346 (14.2%) horses successfully returned to racing after SDFT injuries. Multivariable model building revealed that an increase in the total number of injured zones (defined as the total number of zones in which the injured hypoechoic area was observed at the time of ultrasonographic diagnosis of SDFT injury) was associated with an increased risk of failure to return to racing after SDFT injury. Horse characteristics, such as age, body mass and sex, were not associated with a successful return to racing. In the rehabilitation of cases with larger (longer) lesions, more effective and careful medical management may be needed for an improvement in the athletic outcomes.
Subject(s)
Horse Diseases/physiopathology , Running , Tendon Injuries/veterinary , Animals , Body Composition , Cohort Studies , Female , Horses , Male , Retrospective Studies , Risk Factors , Tendon Injuries/diagnostic imaging , Tendon Injuries/physiopathology , Tendons , Ultrasonography/veterinaryABSTRACT
To evaluate the anthelmintic effect of Musa spp. leaves, 12 animals were artificially infected with Haemonchus contortus, and another 12 animals were infected with Trichostrongylus colubriformis. Then, both treatment groups were offered 400 g of dried ground banana plant leaves, and the control animals were offered only 1000 g of coast cross hay. During the trials, the animals received weekly physical examinations. The methods used to evaluate the efficiency of this treatment were packed cell volume, total plasma protein and faecal egg counts, and egg hatchability tests were performed on days -2, +3, +6, +9, +13 and +15. Coproculture tests were performed on day -2 to confirm monospecific infections. In the FEC and EHT, a statistically significant difference (0.04, 0.005; p < 0.05) was noted for T. colubriformis. There were no statistically significant differences (p > 0.05) for Haemochus contortus group in all tests. Our results confirmed previous findings suggesting that dried ground banana plant leaves possess anthelmintic activity.
Subject(s)
Anthelmintics/administration & dosage , Haemonchiasis/veterinary , Haemonchus/drug effects , Musa/chemistry , Plant Extracts/administration & dosage , Sheep Diseases/drug therapy , Trichostrongylus/drug effects , Animals , Feces , Haemonchiasis/drug therapy , Haemonchiasis/parasitology , Plant Leaves/chemistry , Sheep , Sheep Diseases/parasitology , Sheep, Domestic , Trichostrongylosis/drug therapy , Trichostrongylosis/parasitology , Trichostrongylosis/veterinaryABSTRACT
OBJECTIVE: Single-incision laparoscopic surgery (SILS) represents the recent advance in laparoscopic surgery claiming to be less invasive than conventional laparoscopic surgery. This study investigates the feasibility and safety of the procedure in colorectal surgery and reports the experiences in our center. METHODS: We retrospectively evaluated 41 consecutive patients surgically treated in our institution (February 2011-April 2013). The patient characteristics were evaluated for: gender, age, body mass index and ASA-score. Data included: indication, procedure, intraoperative complications, operation time, number of lymph nodes, postoperative complications, length of stay (LOS), morbidity and cosmesis. RESULTS: SILS was performed in 41 patients including 9 patients with colorectal cancer resection. We performed 3 ileocaecal resections, 11 right hemicolectomies, 7 sigmoidectomies and 20 rectosigmoidectomies. The operation time ranged from 45-210 min (median 123 min). Number of lymph nodes identified, ranged from 1-37 (median n=8). Six post-operative complications (14%) occurred: 1 gastroparesis, 1 subobstruction, 1 anastomotic leak and 3 patients needed a blood transfusion postoperatively. Median LOS was 6 days (range 4-21 days). One delayed complication (2,4%) occurred (eventration). None of the patients died. All patients had satisfactory cosmetic results. CONCLUSIONS: With the proviso that the study population was limited in size, SILS is feasible and is a save procedure in colorectal surgery and the procedure has an obvious cosmetic benefit. The results are comparable to other international reports. Still the procedure should be restricted to selected patients and performed by experienced surgeons. Additional prospective studies are essential to define the further benefit.
Subject(s)
Adenocarcinoma/surgery , Colectomy/methods , Colorectal Neoplasms/surgery , Laparoscopy/methods , Adenocarcinoma/pathology , Adult , Aged , Aged, 80 and over , Cicatrix/etiology , Cicatrix/pathology , Cicatrix/prevention & control , Colectomy/adverse effects , Colorectal Neoplasms/pathology , Feasibility Studies , Female , Humans , Laparoscopy/adverse effects , Length of Stay , Male , Middle Aged , Operative Time , Retrospective Studies , Treatment OutcomeABSTRACT
A field survey of resistance was conducted based on the larval packet test technique with synthetic pyrethroids (cypermethrin and deltamethrin) and organophosphates (chlorpyriphos) in Rhipicephalus (Boophilus) microplus field populations from six different regions of the State of São Paulo (Brazil). 82.6% of the populations showed resistance to cypermethrin, 86.36% to deltamethrin and 65.25% to chlorpyriphos, with 50% presenting resistance to both SP and OP acaricide. According to the questionnaires completed by the producers, OP+SP mixtures followed by SP-only formulations were the products most commonly used for controlling the cattle tick in the surveyed areas. The present study showed high occurrence of resistance to SP and OP in the State of São Paulo, Brazil and revealed the type of strategy adopted by small dairy farms in this state. This information is fundamental in order to establish the monitoring of resistance on each farm individually, contributing to the rational use of acaricides for the control of R. (B.) microplus.
Subject(s)
Cattle Diseases/parasitology , Insecticides , Rhipicephalus/growth & development , Tick Infestations/veterinary , Animals , Cattle , Cattle Diseases/prevention & control , Chlorpyrifos , Female , Insecticide Resistance , Male , Nitriles , Pyrethrins , Surveys and Questionnaires , Tick Infestations/prevention & controlABSTRACT
Although glucocorticoid (GC) is widely used for treating hematopoietic malignancies including adult T-cell leukemia (ATL), the mechanism by which leukemic cells become resistant to GC in the clinical course remains unclear. Using a series of T-cell lines infected with human T lymphotropic virus type-I (HTLV-I), the causative virus of ATL, we have dissected the transformation from interleukin (IL)-2-dependent to -independent growth stage. The transformation associates the loss of thioredoxin-binding protein-2 (TBP-2), a tumor suppressor and regulator of lipid metabolism. Here we show that TBP-2 is responsible for GC-induced apoptosis in ATL cells. In the IL-2-dependent stage, dexamethasone induced TBP-2 expression and apoptosis, both of which were blocked by GC receptor (GR) antagonist RU486. Knockdown of TBP-2 consistently reduced the amount of GC-induced apoptosis. In IL-2-independent stage, however, expression of GR and TBP-2 was suppressed and GC failed to induce apoptosis. Forced expression of GR led the cells to mild sensitivity to GC, which was also accomplished by treatment with suberoylanilide hydroxamic acid, a TBP-2 inducer. A transfection experiment showed that TBP-2 expression induced apoptosis in IL-2-independent ATL cells. Thus, TBP-2 is likely to be one of the key molecules for GC-induced apoptosis and a potential target for treating the advanced stage of ATL.
Subject(s)
Carrier Proteins/physiology , Cell Transformation, Viral , Glucocorticoids/pharmacology , Human T-lymphotropic virus 1 , Leukemia-Lymphoma, Adult T-Cell/drug therapy , T-Lymphocytes/drug effects , Carrier Proteins/analysis , Cell Line , Humans , Hydroxamic Acids/pharmacology , Receptors, Glucocorticoid/analysis , Receptors, Glucocorticoid/physiology , VorinostatABSTRACT
REASONS FOR PERFORMING STUDY: It has been suggested that the heel of the horse's hoof expands in the stance phase and this reduces the concussion at impact and helps pump blood into the hoof. Therefore, farriers usually leave a gap in the heel region when using the traditional nailed shoe. Recently glued shoes which are attached firmly to the heel have been developed and these could restrict heel movement. OBJECTIVE: To compare the degree of mediolateral heel movement between glued and nailed shoes. METHODS: Seven Thoroughbreds were used. Either their fore- or hind hooves were shod with plain aluminium shoes, attached first with glue and later with nails. Measurements were collected continuously with a displacement sensor fixed between the medial and lateral hoof walls at the heel. The horses ran on a treadmill at a walk (1.8 m/s), trot (3.5 m/s), canter (8 m/s) and gallop (12 m/s). The mediolateral heel movement in a nonweightbearing position was set at zero for each hoof and thus positive and negative numbers represented expansion and contraction, respectively. Average values of 10 consecutive strides at each speed were compared between the 2 shoeing methods by paired t test. RESULTS: At all running speeds, the heels expanded in the first 70-80% of the stance phase and contracted at breakover. The total heel movement calculated as the sum of the maximum expansion and contraction value was less with glued shoeing than with nailed shoeing for walking (all limbs), trotting (all limbs), cantering (leading forelimb and both hindlimbs) and galloping (both hindlimbs). CONCLUSIONS: Glueing restricted heel movement, suggesting possible interference with shock absorption and blood pumping in the hoof. Further study is needed to evaluate the influence of glued shoeing on hoof mechanics.
Subject(s)
Foot/physiology , Horses/physiology , Locomotion/physiology , Animals , Biomechanical Phenomena , Forelimb , Hindlimb , Hoof and Claw , ShoesABSTRACT
REASONS FOR PERFORMING STUDY: Although the main cause of injury to the superficial digital flexor tendon (SDFT) is assumed to be high intensity loading of the tendon, to date the forces exerted on the SDFT during cantering have never been measured. OBJECTIVE: To measure the force exerted on the SDFT at walk, trot and canter on a treadmill. METHODS: Arthroscopically implantable force probes (AIFP) were implanted in the SDFT of the left and right forelimbs of 8 Thoroughbred horses (480-565 kg). The output of the AIFP was calibrated using the SDFT force calculated by inverse dynamics and an in vitro model of the lower forelimb at trot. The AIFP output was recorded at 1000 Hz at the walk, trot and canter (9 m/s) on a flat treadmill. RESULTS: AIFP data were analysed successfully in 13 measurement sessions at the walk and trot, in the leading forelimb in 8 sessions at canter and in the trailing forelimb in 5 sessions at canter. The mean ± s.d. maximal force in the SDFT was 3110 ± 1787 N at the walk, 5652 ± 2472 N at the trot, 7030 ± 2948 N in the leading forelimb and 6453 ± 2940 N in the trailing forelimb at canter. CONCLUSIONS: The force in the SDFT increases with running speed from the walk to the canter. The force in the SDFT could not be measured at the gallop. Further study is needed to determine the force in the SDFT at high speed, because it is important for preventing injuries to the SDFT to limit overloading of this tendon.
Subject(s)
Forelimb/physiology , Gait/physiology , Horses/physiology , Tendons/physiology , Animals , Biomechanical Phenomena , Exercise Test , Female , Male , Stress, Mechanical , Telemetry , Transducers, PressureABSTRACT
In the present paper, we examined a mechanism of the papaverine induced relaxation in the smooth muscle of non-pregnant rat uterus. The hyperosmotic 65 mM KCl (H-65K+)-or oxytocin-induced contraction in the uterus was inhibited by an addition of papaverine in a concentration-dependent manner. Papaverine did not increase both cAMP and cGMP contents in the uterus in the presence of H-65K+ or oxytocin. In fura 2 loaded muscles, papaverine did not affect an increase of [Ca2+]i level by high K+ or oxytocin. In permeabilized muscles, papaverine had no effect on the Ca2+-induced contraction. H-65K+ and oxytocin increased the rate of oxygen consumption 1.8 and 1.5 times higher than that in the resting condition, respectively. The increase of oxygen consumption in the H-65K+ or oxytocin was significantly inhibited by papaverine (1-100 microM). These results suggested that papaverine inhibits smooth muscle contraction mainly by inhibition of mitochondrial respiration in rat uterus as well as guinea pig ileum, which shows a highly spontaneous activity and a highly metabolic dependency of a contraction.
Subject(s)
Muscle, Smooth/drug effects , Papaverine/pharmacology , Uterus/drug effects , Animals , Calcium/analysis , Cyclic AMP/analysis , Cyclic GMP/analysis , Female , Guinea Pigs , In Vitro Techniques , Muscle Relaxation/drug effects , Muscle, Smooth/metabolism , Oxygen Consumption/drug effects , Oxytocin/pharmacology , Rats , Rats, WistarSubject(s)
Haloperidol/analogs & derivatives , Haloperidol/blood , Parkinson Disease, Secondary/blood , Parkinson Disease, Secondary/chemically induced , Pyridinium Compounds/blood , Adult , Cytochrome P-450 CYP2D6/genetics , Cytochrome P-450 CYP2D6/metabolism , Cytochrome P-450 CYP3A , Cytochrome P-450 Enzyme System/metabolism , Female , Humans , Middle Aged , Mixed Function Oxygenases/metabolismABSTRACT
The effects of CYP2E1 genotypes on the blood ethanol and acetaldehyde levels were investigated in a pair of Japanese volunteers whose ADH2, ADH3 and ALDH2 genotypes were identical but whose CYP2E1 genotypes were different. In the same way, the effects of ALDH2 and ADH2 on the ethanol elimination kinetics were also studied. The predicting 95% confidence bounds determined on regression analysis of the data suggested that after venous injection of ethanol, the blood ethanol and acetaldehyde concentrations in a volunteer normal homozygous for ALDH2 (ALDH2*1/1) were lower than in a heterozygous one (ALDH2*1/2). Also, the blood ethanol and acetaldehyde concentrations in a volunteer with the c2 and C alleles of CYP2E1 (c1/c2 and C/D) were lower than in one without the c2 and C alleles (c1/c1 and D/D). However, there were no significant differences in the blood ethanol and acetaldehyde concentrations between volunteers with ADH2*1 (ADH2*1/1) and without ADH2*1 (ADH2*1/2).
Subject(s)
Aldehyde Dehydrogenase/genetics , Cytochrome P-450 CYP2E1/genetics , Ethanol/pharmacokinetics , Acetaldehyde/blood , Acetaldehyde/pharmacokinetics , Adult , Aldehyde Dehydrogenase, Mitochondrial , Alleles , Cytochrome P-450 CYP2E1/metabolism , DNA/analysis , DNA Primers/chemistry , Ethanol/blood , Genotype , Humans , Polymerase Chain Reaction , Regression AnalysisABSTRACT
Epidemiological and genetic studies of alcoholism and schizophrenia have been performed, and in this study, the human serotonin receptor (HTR2) polymorphism was examined in 75 alcoholics and 31 schizophrenic patients. We found that there might not be a significant difference between these psychiatric disease patients and controls in the frequency of the C1/C2 HTR2 gene (MspI polymorphism). The results suggest that the human HTR2 MspI polymorphism might not be associated with a risk factor for developing alcohol dependence or susceptibility to schizophrenia. It is possible that there may be a racial difference in the frequency of the C1/C2 gene between Japanese and Caucasians. Further studies are required to determine whether or not the novel serotonin receptor polymorphism reflects the pathogenesis of alcoholism or schizophrenia.
Subject(s)
Alcoholism/genetics , Polymorphism, Genetic/genetics , Receptors, Serotonin/genetics , Schizophrenia/genetics , Alcoholism/epidemiology , Alcoholism/etiology , Alleles , Asian People/genetics , Gene Frequency/genetics , Humans , Japan/epidemiology , Schizophrenia/epidemiology , Schizophrenia/etiology , White People/geneticsABSTRACT
Abstract In a person with inactive ALDH2 (ALDH2*2) the blood aldehyde concentration tends to rise faster and higher and there are flushing responses which are considered to be a restraint against excessive alcohol drinking. The subjects in this study comprised 71 Japanese alcoholics. Psychiatrists interviewed the patients concerning the clinical features. Alcoholics homozygous (n = 59) for ALDH2*1/ALDH2*1 (Group I) and those heterozygous (n = 12) for ALDH2*1/ALDH2*2 (Group II) were compared. Group II alcoholics included significantly more cases of guilt or personality disorder. These findings indicate that alcoholics with the ALDH2*2 genotype showed generally typical clinical features.
ABSTRACT
We investigated the human serotonin receptor, HTR2 genotype among 73 alcoholics. We found that there might not be a significant difference between alcoholics and controls in the frequency of HTR2 C1/C2 gene (MspI polymorphism). This result suggested that the HTR2 C1/C2 gene might not be associated with the risk factor for developing alcohol dependence. Further studies are required to determine whether or not a novel serotonin receptor polymorphism reflects pathogenesis of alcoholism.
Subject(s)
Alcoholism/genetics , Polymorphism, Genetic , Receptors, Serotonin/genetics , Adult , Genotype , Humans , Male , Middle Aged , Risk FactorsABSTRACT
Pseudomonas aeruginosa encodes three types of xenobiotic efflux pumps, MexAB-OprM, MexCD-OprJ, and MexEF-OprN, which are regulated by the nalB, nfxB, and nfxC genes, respectively, and their high expression renders the cells resistant to multiple species of antibiotics. We evaluated the role of the outer membrane permeability barrier and the efflux pump in lowering the intracellular concentration of fluorescent probes. The wild-type, nalB, nfxB, and nfxC strains with an intact outer membrane showed equally high capability in draining out intracellular fluorescent dye, 2-(4-dimethylaminostyryl)-1-ethylpyridinium and ethidium bromide. When the outer membrane barrier was dismantled by the EDTA treatment, wild-type, nfxC, nfxB, and nalB strains showed significantly different levels of dye accumulation. The polymyxin B-treated cells showed an even more pronounced difference in dye accumulation among the nfxC, nfxB, and nalB mutants. We concluded from these results that the xenobiotic extrusion pumps interplay with the outer membrane permeability barrier in lowering the intracellular substrate concentration. Among three extrusion pumps in P. aeruginosa, MexAB-OprM was the most efficient, followed by MexCD-OprJ and MexEF-OprN pumps for the fluorescent dye extrusion.
Subject(s)
Bacterial Outer Membrane Proteins/metabolism , Pseudomonas aeruginosa/metabolism , Transcription Factors , Bacterial Proteins/genetics , Bacterial Proteins/metabolism , Biological Transport, Active/drug effects , Cell Membrane Permeability/drug effects , DNA-Binding Proteins/genetics , DNA-Binding Proteins/metabolism , Drug Resistance, Multiple , Edetic Acid/pharmacology , Ethidium/pharmacokinetics , Fluorescent Dyes/pharmacokinetics , Genes, Bacterial , Mutation , Polymyxin B/pharmacology , Pseudomonas aeruginosa/drug effects , Pseudomonas aeruginosa/genetics , Pyridinium Compounds/pharmacokinetics , Xenobiotics/metabolismABSTRACT
We cloned and characterized the oprQ gene coding for outer membrane protein OprE3 of Pseudomonas aeruginosa PAO1. The oprQ gene was composed of 1,275 base pairs including a sequence encoding for the signal sequence and a mature protein with a Mr of 44,602. Computer-aided alignment and hydropathy analyses of the predicted amino acid sequences suggested that OprE3 is a transmembrane protein homologous to outer membrane proteins of P. aeruginosa such as OprD2 (OprD) porin and OprE1 (OprE) porin. Susceptibility to several antibiotics of the strains lacking or overproducing OprE3 was indistinguishable from that of the wild-type strain, suggesting that OprE3 is unlikely involved in the diffusion of carbapenems and other beta-lactam antibiotics.
Subject(s)
Bacterial Outer Membrane Proteins , Porins/genetics , Pseudomonas aeruginosa/genetics , Amino Acid Sequence , Anti-Bacterial Agents/pharmacology , Cloning, Molecular , DNA, Bacterial/analysis , Genes, Bacterial , Microbial Sensitivity Tests , Molecular Sequence Data , Porins/metabolism , Pseudomonas aeruginosa/drug effects , Sequence Analysis, DNAABSTRACT
To investigate the relationship between CYP2D6 genotypes (reported to be associated with the susceptibilities to Parkinson's disease and multisystem atrophy) and the possible susceptibility to neuroleptic malignant syndrome (NMS) and subacute myelo-optico-neuropathy (SMON), we analyzed the CYP2D6 gene by polymerase chain reaction and restriction fragment length polymorphism in Japanese schizophrenia patients with a history of NMS. There was no significant difference in the frequency of the poor metabolizer genotype of CYP2D6 between the cases with a history of NMS and controls (p > 0.05). The frequency of the mutation located at the HhaI site in exon 6 of CYP2D6 in the cases was higher, but not significantly (p > 0.05; the mutated allele frequency was 0.25), than that in the controls, schizophrenia patients without NMS (0.11) and healthy controls (0.09). The frequency (0.10) of the HhaI mutation type in patients with a diagnosis of SMON was also not significantly higher than in healthy controls. These results suggest that the poor metabolizer and HhaI polymorphism of CYP2D6 may not be a useful molecular marker for predicting the onset of NMS and SMON.
Subject(s)
Cytochrome P-450 CYP2D6/genetics , Neuroleptic Malignant Syndrome/genetics , Adult , Female , Genotype , Humans , Japan , Male , Middle Aged , Mutation , Myelitis/genetics , Optic Neuritis/genetics , Polymorphism, Restriction Fragment Length , Schizophrenia/complications , Schizophrenia/genetics , Schizophrenia/metabolismABSTRACT
We reported recently that protein D2 (OprD) porin of Pseudomonas aeruginosa bears protease activity (FEBS Letters 394, 179-182, 1996). To identify the catalytic residues of OprD, we introduced the site-directed mutations replacing the putative catalytic triad His156, Asp208, and Ser296 with glutamine, asparagine, and alanine, respectively. The OprD proteins purified from the chromosomal oprD-deficient mutants harboring the plasmids encoding the site-directed mutations showed protease activity less than 0.1% of that of the wild-type OprD. These site-directed mutageneses caused undetectable changes in the pore-forming activity of OprD as measured by single-channel conductance by the planar lipid bilayer. The minimum inhibitory concentration of imipenem in mutants having the replaced catalytic triads was identical with that in the wild-type strain. On the other hand, introduction of the mutation at His367 replacing with glutamine, the site that is supposed to be unrelated to the catalytic sites, showed the unchanged protease activity. These results unequivocally demonstrate that OprD is the protease bearing porin and catalyzes the reaction at His156, Asp208, and Ser296 residues.