Impact of control measures including decolonization and hand hygiene for orthopaedic surgical site infection caused by MRSA at a Japanese tertiary-care hospital

BACKGROUND

Meticillin-resistant Staphylococcus aureus (MRSA) is the most common pathogen in orthopaedic surgical site infections (SSIs). However, few studies have investigated the transmission process of orthopaedic MRSA SSI.

AIM

To investigate the transmission process of orthopaedic MRSA SSI using epidemiological and molecular analyses and to determine a method to prevent MRSA SSI in nosocomial orthopaedic surgery.

METHODS

Active MRSA surveillance, preoperative decolonization and contact precautions for MRSA-positive cases was performed at our institution. Changes in epidemic strains were evaluated and the possibility of transmission from patients in an orthopaedic ward of a Japanese tertiary-care hospital was assessed by genotyping stored MRSA strains. In addition, data on the prevalence of MRSA SSI, MRSA colonization, and use of an alcohol antiseptic agent (mL/patient-days) during 2005-2022 were retrospectively assessed.

FINDINGS

SCCmec type II strain in the SSI group decreased over time, associated with fewer outbreaks. Even during a period of high infection rates, no cases of transmission-induced SSI from nasal MRSA carriers were identified. The infection rate correlated negatively with the use of an alcohol antiseptic agent (r = -0.82; P < 0.0001). Two cases among five nasal carriers developed MRSA SSI caused by strains different from those related to nasal colonization.

CONCLUSION

The infection control measures for transmission from the hospital reservoirs including strict adherence to hand hygiene and decolonization of carriers is likely to be important for the prevention of orthopaedic MRSA SSI. However, the need for contact precautions for decolonized nasal carriers might be low.

The impact of repeat FNA in non-diagnostic and indeterminate thyroid nodules: A 5-year single-centre experience

INTRODUCTION

FNA is a well-established method for the preoperative diagnosis of thyroid nodules, but limitations still reside among non-diagnostic and indeterminate samples. The objective of the present study was to assess the impact of repeat FNA in thyroid nodules primarily classified as non-diagnostic and indeterminate, with the evaluation of the diagnostic resolution rate after the reassessment of the nodule.

METHODS

We retrospectively collected all cases of thyroid FNA at our institution in the last 5 years that had one or more repeat aspirations of the same nodule, calculating the percentage of samples with change in the diagnostic category. Additional collected data included sex, age and interval between the repeat aspirations.

RESULTS

One hundred and seventy-eight specimens from 167 patients (140 female, 27 male) with a median age of 56 years (range 11-90) were included in the study. Among the 86 cases primarily classified as non-diagnostic, 25 (29.1%) remained in the same category after the first reassessment and only 18 (20.9%) after the second repeat aspiration. Among the 40 indeterminate cases, only 10 (25%) retained their status after the second aspiration, with no change after the third assessment.

CONCLUSION

Repeat aspiration of non-diagnostic and indeterminate thyroid nodules had a positive impact in both groups, with diagnostic resolution rates of 80% and 75%, respectively. The present study therefore endorses the use of such strategy for the initial follow-up of nodules with no definite diagnosis, especially in low-resource centres with limited access to modern molecular technologies.

What factor within the Japanese Association for Acute Medicine (JAAM) disseminated intravascular coagulation (DIC) criteria is most strongly correlated with trauma induced DIC? A retrospective study using thromboelastometry in a single center in Japan

Purpose

The diagnostic criteria for disseminated intravascular coagulation (DIC) established by the Japanese Association for Acute Medicine (JAAM) is able to diagnose DIC accurately and promptly. The aim of this retrospective study is to evaluate the degree of association between each parameter of JAAM DIC criteria and the diagnosis of trauma induced DIC (T-DIC) utilizing thromboelastometry (ROTEM).

Methods

Trauma patients transported to our hospital with ROTEM performed in the emergency department between January 2013 and December 2015 were enrolled in this study. We evaluated (1) the characteristics of T-DIC, (2) the relationships between T-DIC and each parameter of the JAAM DIC criteria and (3) the diagnostic accuracies of each parameter for T-DIC by statistical measurement.

Results

All 72 patients (21 T-DIC and 51 control) were included in primary analysis. T-DIC was significantly related to younger age, more severe trauma scores, more cases of massive transfusions, and remarkable coagulation abnormality detected by standard coagulation tests. In the cases of T-DIC, ROTEM showed longer clotting time, lower acceleration, lower clot firmness, and inhibited fibrinolysis in EXTEM/INTEM. Within the JAAM DIC score, PT-INR ≥1.2 was the most accurate factor for T-DIC diagnosis; sensitivity 60.0%, specificity 100.0%, and accuracy 88.7%. PT-INR ≥1.2 was statistically correlated with the JAAM DIC score (p < 0.001, r = 0.709). The univariate analysis based on 1.2 of PT-INR indicated statistical differences in most categories of ROTEM, which is similar to analysis performed for the presence and absence of T-DIC.

Conclusions

Among JAAM DIC criteria, the PT-INR ≥1.2 was the most accurate factor for both the diagnosis of T-DIC and the evaluation of its severity.

Deciphering the DNA repair protein, Rad23 from kuruma shrimp Marsupenaeus japonicus: full-length cDNA cloning and characterization

AIMS

 Lesions of DNA are removed by nucleotide excision repair (NER) process in the living systems. NER process-related host factors are believed to aid recovery steps during viral integration. Here, we report identification and characterization of a DNA repair molecule Rad23 from kuruma shrimp Marsupenaeus japonicus.

METHODS AND RESULTS

The full-length cDNA of M. japonicus Rad23 gene (MjRad23) has 1149 bp coding for a putative protein of 382 amino acids with a 5' untranslated region (UTR) of 92 bp and 3' UTR region of 1116 bp. Quantitative expression analysis revealed MjRad23 is constitutively expressed in all the organs of healthy shrimp, whereas with high level in muscle tissue. Although MjRad23 expression is observed in every haemolymph samplings to post-white spot syndrome virus infection, high expression is recorded at 2 h post infection (h.p.i.). MjRad23 consists of putative functional domains including one ubiquitin domain (UBQ), two ubiquitin-associated domains (UBA) and one heat-shock chaperonin-binding motif (STI1). Multiple alignment of MjRad23 with Rad23 of other species showed highly significant identity ranging from 37 to 53%; however, high homology is observed with Rad23 of Bombyx mori (BmRad23). UBQ domain region alignment revealed maximum of 66% homology with Rad23 of Apis melifera (AmRad23). MjRad23 clustered with invertebrate sector along with insect species in evolution analysis. Three-dimensional structural analyses demonstrated the highest identity between MjRad23 and human Rad23A (hHR23A).

CONCLUSIONS

The present work revealed the presence of MjRad23 gene, which is essential in DNA repair process. Further studies are required to clarify the involvement of MjRad23 in NER process.

SIGNIFICANCE AND IMPACT OF THE STUDY

This is the first report on identification and characterization of DNA repair protein in crustaceans, which will lead to further investigation to explore the molecular mechanisms behind the NER process.

Preliminary assessment of reproductive technologies in wood bison (Bison bison athabascae): Implications for preserving genetic diversity

Since the high prevalence of bovine tuberculosis and brucellosis in free-ranging wood bison in the Canadian north poses a threat to nearby healthy bison populations, commercial bison and cattle ranches, and potentially to humans, there is considerable impetus to salvage the genetics of infected bison and maintain a disease-free herd. In that regard, there is a great need to develop appropriate reproductive technologies. Therefore, the objective of this study was to develop protocols to produce and cryopreserve wood bison embryos (based on protocols used for cattle). Cumulus oocyte complexes (COC) aspirated from ovaries recovered after slaughter were matured in vitro, and fertilized with either frozen-thawed semen or chilled epididymal spermatozoa. Although both sources of spermatozoa resulted in acceptable rates of fertilization (64.4%, n=45; 89.2%, n=28, respectively) and cleavage (75.0%, n=40; 92.5%, n=40), production of morulae (7.5%, n=40; 25.0%, n=40) and blastocysts (7.5%, n=40; 10.0%, n=40) was low. Morulae- and blastocyst-stage embryos were frozen-stored by vitrification. To our knowledge, this is the first report regarding the in vitro production and cryopreservation of bison embryos for genetic recovery of diseased wood bison. These techniques have substantial potential for conserving and managing the genetic diversity of wild bison, and may also have important management implications for genetic salvage of diseased bison populations in North America.

A simple method for evaluating abnormal lengthening of the QT interval during the face immersion test

The slope of the relation between the unadjusted QT interval and heart rate during the face immersion test has been reported to be useful as an index for predicting an abnormal lengthening of the QT interval for children with nonfamilial long QT syndrome. Our goals were to determine whether we can replace the slope of the QT/heart rate relation calculated from all data with that calculated from fewer data and to determine whether we can replace the slope with the corrected QT value by heart rate (QTc value) at the minimum heart rate. We studied 19 children with a prolonged QT interval and 54 control children by using statistical analysis. The slope calculated from the selected data points (at least four) was in agreement with the slope calculated from all data, and the relationship between the slope and the QTc value at the minimum heart rate showed a high correlation. It was determined that we can replace the slope calculated from all data with that calculated from at least four data points and replace the slope with the QTc value at the minimum heart rate as an index for predicting an abnormal lengthening of the QT interval.

Hyperoxia-induced acute lung injury using a pig model: correlation between MR imaging and histologic results

PURPOSE

To correlate MR imaging findings with pathology in experimental hyperoxia-induced acute lung injury, which has similar pathology to diffuse alveolar damage (DAD).

MATERIALS AND METHODS

Seventeen Yorkshire pigs were studied. These animals were exposed to more than 80% oxygen for 24, 48, 72, and 96 hours in a sealed cage. The lungs were removed and inflated with air infused through the trachea, and then examined by both MRI and high-resolution CT (HRCT). T1-weighted spin-echo (T1WSE), T2-weighted fast (T2WFSE), and half-Fourier acquisition single-shot turbo spin-echo (HASTE) sequences were performed.

RESULTS

Severity in MR findings and signal-to-noise ratios (SNR) on MR images were well correlated with pathological scores. CT values were also correlated well with pathologic scores. Abnormal SNR values were obtained from a pathological score of 5, whereas abnormal CT values were obtained from a pathological score of 15. Furthermore, significant differences in SNR were observed in each histopathological phase.

CONCLUSION

SNRs on MR images were superior to CT values in detecting early pathologic changes in DAD. MR study also is potentially useful for evaluation of the histopathological phases in acute lung injury.

Phantom evaluation of scatter and attenuation correction in thallium-201/technetium-99m acquisition in myocardial perfusion single-photon emission computed tomography

PURPOSE

This phantom study was carried out to evaluate the usefulness of scatter correction combined with transmission-based attenuation correction in separate and simultaneous 201Tl/99mTc myocardial SPECT.

METHODS

An anthropomorphic torso phantom was used in this study. We used the triple-energy-window (TEW) method for scatter correction and transmission computed tomography (TCT) images for attenuation correction. Images without corrections (UC) and images with corrections (SAC) for scatter and attenuation were reconstructed for the evaluation.

RESULTS

The differences in defect size between 99mTc and 201Tl UC images led to interpretation errors in separate (separate protocol) and simultaneous dual-isotope studies (simultaneous protocol). These errors were more prominent in the infero-posterior wall in the simultaneous protocol. Improvement for overestimation in object size and underestimation in defect contrast was visually obtained, and increased contrast was also shown by the myocardium-to-defect count (MD) ratios on SAC images in the separate and simultaneous protocols. However, 201Tl SAC images in the simultaneous protocol still had less defect contrast than the corresponding 201Tl SAC images in the separate protocol.

CONCLUSIONS

From the results of our phantom experiment, separate rest 201Tl/stress 99mTc-sestamibi acquisitions may be recommended in clinical practice. Further clinical and phantom studies will be needed to validate the method using scatter correction combined with transmission-based attenuation correction.

Increased expression of vascular endothelial growth factor (VEGF) in Castleman's disease: proposed pathomechanism of vascular proliferation in the affected lymph node

Castleman's disease is a lymphoproliferative disorder of unknown etiology characterized by enlarged hyperplastic lymph nodes with marked vascular proliferation. To evaluate the possible involvement of vascular endothelial growth factor (VEGF) in the pathogenesis of Castleman's disease, we studied VEGF expression in sera and lymph nodes from four patients with either the plasma-cell type or mixed type of Castleman's disease. Clinically, one patient had the multicentric type and the others the localized type. The VEGF levels of the sera and the supernatants of the cultured lymph nodes were higher than those of normal controls. VEGF was strongly expressed in plasma cells in the interfollicular region of the lymph nodes, but rarely in normal lymph nodes. The disregulated IL-6 gene expression is considered to be a primary event that could be related to the etiology of this disease. Recently, Kaposi's sarcoma virus/human herpes virus 8 (KSHV/HHV-8) has been reported to be associated with a subset of the multicentric type of Castleman's disease, and a viral homologue of IL-6 (vIL-6) encoded by KSHV/HHV-8 has been shown to induce VEGF expression. Human IL-6 produced in the affected lymph nodes of Castleman's disease may induce paracrine VEGF-production by plasma cells and vascular proliferation in the lymph node. The confirmation of the role of VEGF in the pathogenesis of Castleman's disease may provide a therapeutic strategy.

Bilateral coronary artery dilatation in a child with Noonan syndrome

A rare case of a child with Noonan syndrome who had huge bilateral coronary artery dilatation is presented. Noonan syndrome is one of the most common nonchromosomal syndromes seen in children with cardiovascular abnormalities. Coronary artery abnormality should be considered in Noonan syndrome, because this syndrome may be associated with a higher incidence of coronary anomalies than previously thought.

[CT and MRI in the diagnosis of cardiomyopathy]

Two new noninvasive imaging modalities, electron beam computed tomography (EBCT) and magnetic resonance imaging(MRI), have emerged in recent years and have provided images of the heart with high temporal and spatial resolution. They provides accurate information of myocardial thickness, ventricular shape and volume, wall motion, and ventricular function in patients with cardiomyopathy. In addition, myocardial damage can be evaluated using contrast media. They can give unique diagnostic information above and beyond that of more traditional noninvasive modalities such as two-dimensional echocardiography, left ventriculography and radionuclide technique because both modalities acquire images in three dimensions. They have a possibility to become an alternative modality of the left ventriculography in the diagnosis of cardiomyopathy.

[The incidences of virulence genes in Escherichia coli strains from sporadic diarrheal children]

To investigate the incidence of diarrheagenic Escherichia coli among E. coli strains screened by commercially available O-antigen antisera, we used PCR to isolate 8 virulence genes (eae, bfpA, IpaH, LT, ST, VT1, VT2, and aggR) in 184 E. coli strains sampled from sporadic diarrheal children in our district. eae and bfpA are the localized adherence factor genes of enteropathogenic E. coli (EPEC). IpaH is the invasion antigen gene of enteroinvasive E. coli (EIEC), LT and ST are the toxin genes of enterotoxigenic E. coli (ETEC), VT1 and VT2 are the toxin genes of enterohemorrhagic E. coli (EHEC), and aggR is the adherence factor gene of enteroaggregative E. coli (EAggEC). The results were as follows: eae, 7 (3.8%); bfpA, 0 (0%); IpaH, 0 (0%); LT, 0 (0%); ST, 2 (1.1%); VT, 5 (2.7%); aggR, 8 (4.3%). Seven isolates with eae did not have bfpA, and did not show a localized adherence to HeLa cells. Seven of the 8 isolates with aggR showed aggregative adherence to HeLa cells, while their O-serotypes of them were O111:H21 or O111:HUT. Because of the low incidence of the virulence gene, the commercially available O-antigen antisera was not expected to be useful for the screening of diarrheagenic E. coli, except for EHEC and EAggEC. EAggEC may be important as a pathogen of sporadic diarrhea of children as well as EHEC.

Inhibition of thrombin-induced neuronal cell death by recombinant thrombomodulin and E5510, a synthetic thrombin receptor signaling inhibitor

Thrombin, a serine protease generated by the activation of the blood coagulation cascade following vessel injury, converts fibrinogen to fibrin, activates platelets and several coagulation factors, and plays a pivotal role in thrombosis and haemostasis. Thrombin acts as a mitogen and apoptosis inducer in a dose-dependent fashion. We have previously shown that thrombin caused proliferation of vascular smooth muscle cells (VSMCs). Here, we show that a low concentration of thrombin caused proliferation of mouse neuroblastoma (Neuro-2a) and human neuroblastoma (NB-1) cells, while higher concentrations affected cell viability in a time-dependent manner. Similar effects were observed when thrombin receptor agonist peptide (SFLLRNPNDKYEPF, TRAP) was applied. The dying cells showed nuclear condensation and fragmentation, suggesting that cell death occurred by apoptosis. The extent to which thrombin induced cell death was significantly attenuated by recombinant thrombomodulin (rTM), or by a minimum functional domain of TM, termed E456. Furthermore, a synthetic compound that inhibits signaling from the thrombin receptor, 4-cyano-5,5-bis (4-methoxyphenyl)-4-pentanoic acid (E5510), and the antioxidant N-acetyl L-cysteine (NAC), efficiently prevented thrombin-induced Neuro-2a cell death. Thus, thrombin inhibitors and antioxidant appear to neutralize thrombin toxicity.

Face immersion in cold water induces prolongation of the QT interval and T-wave changes in children with nonfamilial long QT syndrome

We investigated the relation between heart rate and the QT interval using face immersion in cold water in children with long QT syndrome (LQTS) without a family history of this condition, and in control children. The face immersion test revealed that all children with high probability of LQTS had a significantly longer QT interval than control children during face immersion, and that the test could induce T-wave alternans or a notched T-wave in all children with a high probability of LQTS.

Expression of vascular endothelial growth factor in sera and lymph nodes of the plasma cell type of Castleman's disease

To evaluate the possible involvement of vascular endothelial growth factor (VEGF) in the pathogenesis of Castleman's disease, we studied VEGF levels in sera and supernatants of cultured lymph nodes from two patients with the plasma cell type of Castleman's disease, and analysed the expression of VEGF immunohistochemically in the lymph nodes. Clinically, one patient was classified as the localized type and the other as the multicentric type. Histologically, mature plasma cells and hyalinized vessels were prominent in the interfollicular region. The VEGF levels of the sera and the supernatants of cultured lymph nodes of both patients were higher than those of normal controls. VEGF was strongly expressed in plasma cells in the interfollicular region of the lymph nodes of both patients, but rarely in normal lymph nodes. Our results suggest that VEGF may be involved in the marked vascular proliferation in the interfollicular region of the lymph nodes of the plasma cell type of Castleman's disease.

Three cases of pyogenic sacro-iliitis, and factors in the relapse of the disease

Pyogenic sacro-iliitis (PS) is a rare disease in childhood. Three cases of PS are reported that were difficult to diagnose. Scintigraphy and magnetic resonance imaging (MRI) were useful for diagnosis. One patient suffered from an episode of relapse. Seventeen other cases of PS were reviewed in the literature to investigate the incidence of abnormal imaging findings and various factors in disease relapse. It was found that the incidence of abnormal findings by scintigraphy was significantly higher than that by computed tomography (P = 0.0057). The duration of intravenous antibiotic administration of the relapse group (14.7 +/- 4.7 days) was significantly shorter than that of the non-relapse group (24.3 +/- 10.7 days; P = 0.0376). The statistical analysis suggested that intravenous antibiotic administration is necessary at least for 20 days to prevent a relapse of PS.

Inhibition of cytotoxic activity of carp lymphocytes (Cyprinus carpio) by anti-thymocyte monoclonal antibodies

A series of monoclonal antibodies (mAbs) were developed against carp thymocytes and carp immunoglobulin (IgM). Anti-thymocyte mAbs reacted with thymocytes, head kidney lymphocytes (HKL) as well as peripheral blood lymphocytes (PBL) at various proportions. Anti-IgM antibody reacted with HKL and PBL but not with thymocytes. PBL from carp immunized with xenogeneic mouse myeloma cells exhibited cytotoxic activity against target cells but PBL from unimmunized fish showed weak cytotoxicity. Treatment of PBL with anti-thymocyte mAbs and guinea pig complement suppressed the cytotoxic activity dose dependently; however, anti-IgM mAb did not. These results indicate the cytotoxic cells in PBL possess cell surface antigens common to thymocytes.

External radiation therapy of prostatic carcinoma and its relationship to hormonal therapy

From 1980 to 1990, a total of 54 patients with prostatic carcinoma were treated with external radiation therapy at the Kumamoto National Hospital. Ten patients were classified as Stage B, 22 as Stage C, and another 22 as Stage D according to the American Urological Association Clinical Staging System. The 5-year survival for all 54 patients was 30%. The 5-year disease-specific survival was 67% for Stage B, 47% for Stage C, and 26% for Stage D. The 5-year survival was 43% for patients in whom radiation therapy was initiated immediately after the first diagnosis or with less than one year of hormonal therapy, while it was 0% for patients in whom radiation therapy was initiated after more than one year of hormonal therapy (p = 0.01). The cause of intercurrent death was acute myocardial infarction in four patients and acute cardiac failure in one. Four of these patients received hormonal therapy for more than one year. The incidence of radiation-induced proctitis was not severe. This study suggests that long-term hormonal therapy prior to radiation therapy worsens the prognosis of patients with prostatic carcinoma.

Molecular typing of the methicillin resistance determinant (mec) of clinical strains of Staphylococcus based on mec hypervariable region length polymorphisms

We used a method for molecular typing the methicillin resistance determinant (mec) based on the size of the mec-associated hypervariable region amplified by the polymerase chain reaction (PCR) to examine 61 methicillin-resistant Staphylococcus aureus (MRSA), 15 methicillin-resistant (Mcr) S. epidermidis, and 11 Mcr S. haemolyticus clinical isolates. In the 61 MRSA isolates, five sizes of PCR products were observed. The MRSA isolates were grouped into five hypervariable region (HVR) genotypes on the basis of the size of the PCR product. Three different sizes were detected among 15 isolates of Mcr S. epidermidis and two sizes among 11 isolates of Mcr S. haemolyticus. The PCR products amplified from 14 of 15 Mcr S. epidermidis isolates were the same as products amplified from MRSA isolates, which was confirmed by the PCR-SSCP (single-strand conformation polymorphism) method. In methicillin-susceptible isolates, the target gene was not amplified. This method is thought to be useful in epidemiologic investigations of nosocomial infections caused by MRSA. This is the first typing method capable of comparing the mec determinants of MRSA isolates and Mcr coagulase-negative staphylococcal isolates to establish the origin of the mec determinant.

[Molecular typing of the methicillin resistance determinant (mec) of clinical strains of Staphylococcus based on mec hypervariable region length polymorphisms]

We used a method for molecular typing of the methicillin resistance determinant (mec) based on the size of the mec-associated hypervariable region amplified by the polymerase chain reaction (PCR) to examine 106 methicillin-resistant Staphylococcus aureus (MRSA), 9 methicillin-resistant (Mcr) S. epidermidis and 5 Mcr S. haemolyticus clinical isolates. In the 106 MRSA isolates, 5 sizes of PCR products were observed. The MRSA isolates were grouped into five hypervariable region (HVR) genotypes on the basis of the size of the PCR product. The PCR products amplified from 8 of 9 Mcr S. epidermidis isolates were the same as products amplified from MRSA isolates, which was confirmed by the PCR-SSCP (single-strand conformation polymorphism) method. In 32 methicillin-susceptible isolates, the target gene was not amplified. This method is thought to be useful in epidemiological investigations of nosocomial infections caused by MRSA. This is the first typing method capable of comparing the mec determinants of MRSA isolates and Mcr CNS isolates to establish the origin of the mec determinant.

A case of non-tuberculous mycobacterial lymphadenitis diagnosed with new skin tests and PCR

Non-tuberculous mycobacterial (NTM) cervical lymphadenitis has been rarely reported in Japan. We report on a case of a 15 month old child with NTM cervical lymphadenitis who was diagnosed with new skin tests containing NTM antigens and a polymerase chain reaction (PCR) method. These two diagnostic methods were highly useful in the present case, therefore we anticipate they will become available to other Japanese physicians to expedite the diagnosis of NTM lymphadenitis.

Two new tryptophan-derived alkaloids from the Okinawan marine sponge Aplysina sp

Two new indole alkaloids, isoplysin A [2] and D-6-bromohypaphorine [3], have been isolated from the Okinawan marine sponge Aplysina sp. and their structures were elucidated by spectral and chemical means.

Hydroxyl radical generation and membrane fluidity of erythrocytes treated with lipopolysaccharide

The effect of lipopolysaccharide (LPS) and/or bile acids on rat erythrocyte membranes was studied in vitro. Addition of LPS isolated from E. coli (J5 mutant) into the erythrocyte resulted in the decrease of membrane fluidity as determined by spin labelling using electron paramagnetic resonance (EPR). This was accompanied by membrane fragility. It was found that hydroxyl radicals were generated from erythrocytes treated with LPS by using DMPO spin trapping. However, pretreatment of erythrocytes with taurine-conjugated bile acids was found to modify the membrane response induced by LPS. Taurocholic acid (TCA) and tauroursodeoxycholic acid (TUDCA) prevented the decrease of membrane fluidity induced by LPS, and, as a result, the membrane integrity was maintained although no significant changes were observed in the amount of hydroxyl radicals produced by LPS addition. However, taurochenodeoxycholic acid (TCDCA) exhibited little beneficial effect on the dynamic properties and the function of the erythrocyte membranes, although the hydroxyl radical declined markedly in the erythrocytes. Therefore, it is suggested that TCA and TUDCA have a protective effect against LPS-induced membrane fragility by modulating membrane fluidity.

Exponential correction of QT interval to minimize the effect of the heart rate in children

The exponential correction of the QT interval (eQTc) was studied using 12,543 resting electrocardiograms obtained in children (first and seventh graders) who were screened for heart disease in Kagoshima City. The values of eQTc to minimize the effect of the RR interval were estimated using following exponential model, eQTc = (QT interval)/(RR interval)--k. The parameter k = 0.31 was found to be the most useful exponent. The distribution of eQTc values showed a hiatus or break at probability points near p < 0.001 or p < 0.0005. Tentative criteria for an abnormally long eQTc were selected using these points and the following convenient data: 0.430 and 0.435 for the male and female first graders, and 0.440 and 0.445 for the male and female seventh graders, increased by 0.005, respectively. Abnormal values must ultimately be selected using data on patients with the long QT syndrome; however, our findings suggest that the exponential correction of the QT interval may be useful in large-scale screening programs for detecting a QT prolongation in young school children.

Identification of free and esterified hydroxyoctadecadienoates (HODEs) and linoleate-hydroxylating pathway in the epidermis of hairless mice

Epidermal homogenates of hairless mice contained a large amount of lipid material showing a single peak on reverse phase (RP)-high pressure liquid chromatography (HPLC) with a maximum absorbance of 234 nm, which was different in retention time from arachidonate metabolites such as 12-HETE, 15-HETE and 5-HETE. The production of this material was dependent on exogenous linoleate concentration, protein concentration and buffer pH. This material was identified to be a mixture of 13-HODE and 9-HODE on the basis of UV absorbance spectra, retention times on RP-HPLC, straight phase (SP)-HPLC, gas chromatography-mass spectrometry (GC/MS) and mass spectra obtained. As assessed by SP-HPLC after saponification, these two HODEs were found to exist primarily in esterified forms in the skin. Neither substance was produced following heat denaturation of the homogenate. These results indicate that 13- and 9-HODEs are produced from linoleate enzymatically at physiologically relevant levels in the epidermis of hairless mice. Thus, it is possible that these two materials may play some important role in pathophysiology of the skin.

Mechanism of lipid radical formation following exposure of epidermal homogenate to ultraviolet light

It has been suggested that oxygen free radicals are important mediators of lipid peroxidation in the epidermis exposed to ultraviolet (UV) light. However, it is not clear whether it is the superoxide anion radical (O2-.) or the hydroxyl radical (.OH) that plays the major role in producing the lipid radicals (L.) following UV exposure. In this study, we used electron spin resonance (ESR) technique with the spin trap (5,5-dimethyl-1-pyrroline-N-oxide [DMPO]) to determine which active oxygen species is involved in the UV-induced lipid radical formation (DMPO-L.: aN = 15.5 G, aH = 22.7 G). In the presence of superoxide dismutase or the metal-chelating agent, the DMPO-spin adduct spectrum of lipid radicals was reduced remarkably. The lipid radicals were formed by the hydroxyl radical generation system, not the superoxide anion generation system. The hydroxyl radical was found to be the direct active oxygen species that can generate lipid radicals as a result of .OH-mediated hydrogen atom abstraction. Superoxide anion radical stimulated the generation of hydroxyl radical via the iron-catalyzed reaction.

[Nosocomial infections due to methicillin-resistant S. aureus (MRSA) at the Kagoshima University Hospital (2). Susceptibility to antibiotics]

Susceptibility to antibiotics of 123 MRSA strains isolated at the Kagoshima University Hospital in 1989 was examined. The results were as follows: 1) Susceptibility of MRSA strains was excellent to VCM, MINO, and RFP, followed by IMP, CLDM, and CPFX. However, most strains were resistant to PCG, MPIPC, ABPC, CET, CMZ, CZON, GM, and AMK. 2) Five strains highly resistant to RFP were isolated. Three of these strains were isolated on the ward for tuberculosis. This suggests easy development of resistance to RFP by MRSA. 3) Differences in susceptibility to antibiotics between coagulase type II and type VII strains were examined. The cumulative percentage of type II strains susceptible to CLDM (MICs less than 0.5 microgram/ml) was 15.3%, and that of type VII was 45.2%. Strains resistant to CLDM were more frequently isolated among type II than among type VII strains (p less than 0.001). A similar relationship between strains and antibiotics was also found with EM and CPEX. On the other hand, the cumulative percentage of type II strains susceptible to AMK (MICs less than 25 micrograms/ml) was 89.7%, and that of type VII was 9.7%. Strains resistant to AMK were more frequently isolated among type VII than among type II strains (p less than 0.001).

[Nosocomial infections due to methicillin-resistant S. aureus (MRSA) at the Kagoshima University Hospital (1). Coagulase typing of MRSA]

Nosocomial infection due to MRSA at the Kagoshima University Hospital and their coagulase typing were examined using S. aureus (349 strains) clinically isolated in 1989. The results were as follows: 1) S. aureus consisted of 43.6% of MRSA and 56.7% of Methicillin-sensitive S. aureus (MSSA). 2) MRSAs were recovered most frequently from the specimens from the respiratory tract (47.8%). 3) The isolation of MRSA gradually increased in frequency from January to August; however, that of MSSA did not show a similar tendency. 4) The isolation of MRSA was higher in frequency in the surgical wards, the ICU and the pediatric ward. 5) When classified into 8 coagulase types, MRSAs (133 strains) consisted of only 3 types (54.1% of type II, 32.3% of type VII, and 12.0% of type IV), whereas MSSAs contained all coagulase types. As compared with the results of coagulase typing at other institutions, the incidence of type VII was much more frequent at our hospital. 6) A few coagulase types of MRSA appeared in each ward. Also, type II MRSA strains increased in June and July, and type VII MRSA increased in August. However, MSSA strains did not show any similar tendency.

Involvement of active oxygen in lipid peroxide radical reaction of epidermal homogenate following ultraviolet light exposure

To elucidate the radical mechanism of lipid peroxidation induced by ultraviolet light (UV) irradiation, an electron spin resonance (ESR) study was made on epidermal homogenate prepared from albino rat skin. The exposure of the homogenate to UV light resulted in an increase in lipid peroxide content, which was proportional to the time of UV exposure. Using ESR spin trapping (dimethyl-1-pyrroline-N-oxide, DMPO), the DMPO spin adduct spectrum of lipid radicals (L.) was measured following UV exposure (DMPO-L.:aN = 15.5 G, aH = 22.7 G), as was the spectrum of DMPO-hydroxyl radical (DMPO-OH, aN = aH = 15.5 G). In the presence of superoxide dismutase, the DMPO spin adduct spectrum of lipid radicals was found to be reduced remarkably. Therefore, it was shown that the generation of the lipid radicals partially involves superoxide anion radicals, in addition to hydroxyl radicals. In the ESR free-radical experiment, an ESR signal appeared at g = 2.0064 when the ESR tube filled with homogenate was exposed to UV light at -150 degrees C. The temperature-dependent change in the ESR free radical signal of homogenate exposed to UV light was observed at temperatures varying from -150 degrees C to room temperature. By using degassed samples, it was confirmed that oxygen is involved in the formation of the lipid peroxide radicals (LOO.) from the lipid radicals (L.).

Arachidonate metabolism in bovine gallbladder mucosa

Incubation of [1-14C] arachidonicacid (AA) with homogenates of bovine gallbladder mucosa in the presence or absence of reduced glutathione (GSH) generated large amounts of products that cochromatographed with PGE2 and 6-keto-PGF1 alpha and small amounts of products comigrating with PGF2 alpha, TxB2 and PGD2. In the presence of GSH PGE2-like material was predominantly produced while in the absence of GSH 6-keto-PGF1 alpha-like material was a major product. Identification of PGE2 was performed by its chemical conversion with NaBH4 or KOH treatments and by gas chromatography-mass spectrometry. Identification of 6-keto-PGF1 alpha was confirmed by gas chromatography-mass spectrometry. Gallbladder muscle produced predominantly 6-keto-PGF1 alpha in the presence or absence of GSH. The total amount of cyclooxygenase products was approximately 2 times higher in the mucosa than in the muscle. These results indicate that bovine gallbladder mucosa contains higher levels of fatty acid cyclooxygenase, and PGE2 isomerase and PGI2 synthetase in a proportion different from that in the muscle.

[Methicillin-resistant Staphylococcus aureus infection in the Kagoshima University Hospital--special attention to prevalence in otolaryngological infectious disease]

A retrospective study of the characteristics of MRSA (methicillin resistant S. aureus) in Kagoshima University Hospital and its ENT department was reported. There were 231 samples (104 strains) MRSA in all S. aureus 448 samples from Jan. to Sep. 1989 in Kagoshima University Hospital, in which 58 strains (55.8%) were coagulase type II and 35 strains (33.7%) were type VII. The much more predominant numbers of MRSA were observed in all the cases inpatients clinics in surgery, pediatrics, urology, gynecology and dermatology than internal medicine as well as outpatients clinics. In ENT department of this hospital, only 15.4% of all S. aureus were MRSA. On the other hand, bacteriological survey showed 26% of MRSA out of all S. aureus which were detected at Tokyo clinical research center on otorrhea in the patients with chronic otitis media as multicenter clinical trial of Japan. Two cases involved by MRSA after postoperative administration of many types of antibiotics were also demonstrated. These MRSAs were producing type II coagulase and very high concentrations of MICs to many antibiotics were observed. But these cases were not severe and MINO (minocyclin) or GM (gentamicin) were so effective. The effect of combined therapy of some antibiotics or antimicrobial agents was discussed briefly.

Acute cytogenetic effects of tyramine, MTCAs, NaCl and soy sauce on rat bone marrow cells in vivo

The acute cytogenetic effects of tyramine and MTCAs, precursors of the mutagen present in soy sauce, were studied with the in vivo chromosome aberration test in rat bone marrow cells. The chemicals were administered intraperitoneally. Statistically significant positive results were obtained with tyramine at a dose of 5 mmole/kg (686 mg/kg) body weight and with MTCAs at doses over 0.50 mmole/kg (115 mg/kg) body weight, respectively. Chromosome aberrations (CA) induced by L-proline co-administered with either tyramine or MTCAs were significantly lower than those induced by each chemical alone. These data suggest that L-proline, after endogenous nitrosation, became nitrosoproline and suppressed CA, and that, as a result of in vivo nitrosation of tyramine and MTCAs, they became mutagenic nitroso compounds showing positive results. Statistically significant positive results were obtained by administration of 40 mmole NaCl/kg body weight (2338 mg/kg). The cocarcinogenic role of NaCl with tyramine was suggested because soy sauce contains about 18% NaCl.

Acute cytogenetic effects of tyramine and MTCAs on mouse bone marrow cells in vivo by the micronucleus test

We studied the acute cytogenetic effects of tyramine and MTCAs--precursors of the mutagen present in soy sauce--on mouse bone marrow cells in vivo by the micronucleus test. The incidence of MNPCE in bone marrow cells gradually increased and reached a maximum level 24 h after intraperitoneal injection of tyramine or MTCAs and decreased within 36 h. A dose-dependent increase in MNPCE was clearly observed for both compounds. Compared to the values for the untreated control, significant positive results were obtained with 0.5 mmole tyramine/kg (68.5 mg/kg) and with 0.1 mmole MTCAs/kg (23 mg/kg) 24 h after intraperitoneal administrations. Micronuclei were significantly induced but no severe reduction in the ratio of PCEs/NCEs was observed.