Faecal freezing preservation period influences colonization ability for faecal microbiota transplantation.

AIMS: There has been growing interest in faecal microbiota transplantation (FMT) as treatment. Although, frozen donor faeces preserved at -20°C has been widely used for practical advantages, freezing at -20°C can affect bacterial viability. Adequacy evaluation of fresh and frozen faeces as the transplant is necessary for the methodological improvement of FMT. METHODS AND RESULTS: The viable bacterial compositions of faecal specimens under fresh and freezing conditions were compared by a microbiome analysis using propidium monoazide (PMA microbiome). In addition, recovery abilities from bacterial reduction by antibiotics were compared between fresh and frozen FMT using a murine model. PMA microbiome results suggested that freezing and freeze-thawing did not significantly affect in vitro faecal bacterial viability. However, the recovery effect from antimicrobial cleansing in frozen FMT was reduced in a freezing time-dependent manner, especially prominent in Actinobacteria and Bacteroidetes phyla. CONCLUSIONS: Short-term freezing preservation of faeces exhibited maintenance of enteric colonization ability in frozen FMT in comparison to 1 month -20°C-preservation. SIGNIFICANCE AND IMPACT OF THE STUDY: Long-term -20°C-preservation of transplanted faeces can result in instability of the clinical outcome in FMT therapy. The standardization of practical procedures of FMT therapy according to disease types is desirable.

Construction and molecular characterization of a T-cell receptor-like antibody and CAR-T cells specific for minor histocompatibility antigen HA-1H.

The genetic transfer of T-cell receptors (TCRs) directed toward target antigens into T lymphocytes has been used to generate antitumor T cells efficiently without the need for the in vitro induction and expansion of T cells with cognate specificity. Alternatively, T cells have been gene-modified with a TCR-like antibody or chimeric antigen receptor (CAR). We show that immunization of HLA-A2 transgenic mice with tetramerized recombinant HLA-A2 incorporating HA-1 H minor histocompatibility antigen (mHag) peptides and ß2-microglobulin (HA-1 H/HLA-A2) generate highly specific antibodies. One single-chain variable region moiety (scFv) antibody, #131, demonstrated high affinity (KD=14.9 nM) for the HA-1 H/HLA-A2 complex. Primary human T cells transduced with #131 scFV coupled to CD28 transmembrane and CD3ζ domains were stained with HA-1 H/HLA-A2 tetramers slightly more intensely than a cytotoxic T lymphocyte (CTL) clone specific for endogenously HLA-A2- and HA-1 H-positive cells. Although #131 scFv CAR-T cells required >100-fold higher antigen density to exert cytotoxicity compared with the cognate CTL clone, they could produce inflammatory cytokines against cells expressing HLA-A2 and HA-1 H transgenes. These data implicate that T cells with high-affinity antigen receptors reduce the ability to lyse targets with low-density peptide/MHC complexes (~100 per cell), while they could respond at cytokine production level.

Multi-drug-resistant Staphylococcus aureus and future chemotherapy.

Staphylococcus (S.) aureus silently stays as our natural flora, and yet sometimes threatens our life as a tenacious pathogen. In addition to its ability to outwit our immune system, its multi-drug resistance phenotype makes it one of the most intractable pathogenic bacteria in the history of antibiotic chemotherapy. It conquered practically all the antibiotics that have been developed since 1940s. In 1961, the first MRSA was found among S. aureus clinical isolates. Then MRSA prevailed throughout the world as a multi-resistant hospital pathogen. In 1997, MRSA strain Mu50 with reduced susceptibility to vancomycin was isolated. Vancomycin-intermediate S. aureus (VISA), so named according to the CLSI criteria, was the product of adaptive mutation of S. aureus against vancomycin that had long been the last resort to MRSA infection. Here, we describe the genetic basis for the remarkable ability of S. aureus to acquire multi-antibiotic resistance, and propose a novel paradigm for future chemotherapy against the multi-resistant pathogens.

High-resolution CT findings in Streptococcus milleri pulmonary infection.

AIM: To assess pulmonary high-resolution computed tomography (CT) findings in patients with acute Streptococcus milleri pulmonary infection. MATERIALS AND METHODS: Sixty consecutive patients with acute S. milleri pneumonia who had undergone high-resolution CT chest examinations between January 2004 and March 2010 were retrospectively identified. Twenty-seven patients with concurrent infections were excluded. The final study group comprised 33 patients (25 men, 8 women; aged 20-88 years, mean 63.1 years) with S. milleri infection. The patients' clinical findings were assessed. Parenchymal abnormalities, enlarged lymph nodes, and pleural effusion were evaluated on high-resolution CT. RESULTS: Underlying conditions included malignancy (n = 15), a smoking habit (n = 11), and diabetes mellitus (n = 8). CT images of all patients showed abnormal findings, including ground-glass opacity (n = 24), bronchial wall thickening (n = 23), consolidation (n = 17), and cavities (n = 7). Pleural effusion was found in 18 patients, and complex pleural effusions were found in seven patients. CONCLUSION: Pulmonary infection caused by S. milleri was observed mostly in male patients with underlying conditions such as malignancy or a smoking habit. The CT findings in patients with S. milleri consisted mainly of ground-glass opacity, bronchial wall thickening, pleural effusions, and cavities.

Response control of RPLGD for gamma-ray dose measurement using lead filters for BNCT.

Boron Neutron Capture Therapy (BNCT) is a cell-selective radiotherapy using a neutron capture reaction of 10B. In recent years, Accelerator Based Neutron Sources (ABNS) are under development instead of nuclear reactors for the next-generation neutron irradiation system for BNCT. However, ABNS as well as nuclear reactor usually generates unavoidable secondary gamma-rays by neutron-nuclear reactions such as capture reaction. In this research, we aimed to develop a separate measurement method of only gamma-rays in a mixed field of neutrons and gamma-rays using a fluorescent glass dosimeter (RPLGD), because most dosimeters have sensitivity to both radiation types. For this purpose, we proposed a lead filter method using two RPLGDs and lead filters. However, this method has a problem that the sensitivity to low energy gamma-rays (∼100 keV) is very small. In order to improve the sensitivity to low energy gamma-rays, we devised a method using a specially shaped lead filter. From theoretical calculations, we have shown that it was possible to estimate the air dose rate of the field where the gamma-ray energy spectrum shape was known for energies up to 10 MeV. In addition, we produced the specially shaped lead filter and experimentally confirmed the validity of the lead filter method using several gamma-ray standard sources and by measurements in a nuclear fuel storage room.

Inhibitory effect of statins on inflammatory cytokine production from human bronchial epithelial cells.

Statins are 3-hydroxy-3-methylglutaryl-co-enzyme A reductase inhibitors of cholesterol biosynthesis, and have been reported to exert pleiotropic effects on cellular signalling and cellular functions involved in inflammation. Recent reports have demonstrated that previous statin therapy reduced the risk of pneumonia or increased survival in patients with community-acquired pneumonia. However, the precise mechanisms responsible for these effects are unclear. In the present study, we examined the effects of statins on cytokine production from lipopolysaccharide (LPS)-stimulated human bronchial epithelial cells (BEAS-2B). Interleukin (IL)-6 and IL-8 mRNA expression and protein secretion in LPS-stimulated cells were inhibited significantly by the lipophilic statin pitavastatin and the hydrophilic statin pravastatin. As these inhibitory effects of statin were negated by adding mevalonate, the anti-inflammatory effects of statins appear to be exerted via the mevalonic cascade. In addition, the activation levels of Ras homologue gene family A (RhoA) in BEAS-2B cells cultured with pitavastatin were significantly lower than those without the statin. These results suggest that statins have anti-inflammatory effects by reducing cytokine production through inhibition of the mevalonic cascade followed by RhoA activation in the lung.

Dietary carbohydrate influences the colocalization pattern of Glucagon-like Peptide-1 with neurotensin in the chicken ileum.

Glucagon-like peptide (GLP)-1 colocalizes with neurotensin (NT) in the same enteroendocrine cells (EECs) of the chicken ileum. The present study was designed to clarify the influence of dietary carbohydrate (CHO) on the colocalization pattern of GLP-1 with NT in the chicken distal ileum. Male White Leghorn chickens at 6 weeks of age (n = 15) were divided into three groups, a control and two experimental (low-CHO and CHO-free), with five chickens in each, and fed control or experimental diets for 7 d. Distal ileum was collected from each bird as a tissue sample and subjected to double immunofluorescence staining to detect GLP-1 and NT. Three types of EEC, GLP-1+/NT+, GLP-1+/NT- and GLP-1-/NT+, were demonstrated in the chicken ileum. GLP-1+/NT+ cells in the control group had a spindle-like shape with a long cytoplasmic process, but those in the experimental groups were round and lacked a cytoplasmic process. The ratio of GLP-1+/NT+ cells was significantly decreased in the two experimental groups compared with that in the control group. The ratio of GLP-1+/NT+ cells was significantly lower than those of GLP-1+/NT- and GLP-1-/NT+ cells in the two experimental groups. Most cells that were immunoreactive for GLP-1 and NT antisera lacked signals of proglucagon (PG) and NT precursor (NTP) mRNA in the experimental groups. The number of EECs expressing PG and NTP mRNA signals showed tendencies for decreases with a reduction of dietary CHO level. These findings suggest that dietary CHO could be a significant regulator of the pattern of colocalization pattern of GLP-1 with NT in the chicken ileum.

Refined human artificial chromosome vectors for gene therapy and animal transgenesis.

Human artificial chromosomes (HACs) have several advantages as gene therapy vectors, including stable episomal maintenance, and the ability to carry large gene inserts. We previously developed HAC vectors from the normal human chromosomes using a chromosome engineering technique. However, endogenous genes were remained in these HACs, limiting their therapeutic applications. In this study, we refined a HAC vector without endogenous genes from human chromosome 21 in homologous recombination-proficient chicken DT40 cells. The HAC was physically characterized using a transformation-associated recombination (TAR) cloning strategy followed by sequencing of TAR-bacterial artificial chromosome clones. No endogenous genes were remained in the HAC. We demonstrated that any desired gene can be cloned into the HAC using the Cre-loxP system in Chinese hamster ovary cells, or a homologous recombination system in DT40 cells. The HAC can be efficiently transferred to other type of cells including mouse ES cells via microcell-mediated chromosome transfer. The transferred HAC was stably maintained in vitro and in vivo. Furthermore, tumor cells containing a HAC carrying the suicide gene, herpes simplex virus thymidine kinase (HSV-TK), were selectively killed by ganciclovir in vitro and in vivo. Thus, this novel HAC vector may be useful not only for gene and cell therapy, but also for animal transgenesis.

Preoperative MRI for predicting pathological changes associated with surgical difficulty during laparoscopic cholecystectomy for acute cholecystitis.

BACKGROUND: Severe inflammation with necrosis and fibrosis of the gallbladder in acute cholecystitis increases operative difficulty during laparoscopic cholecystectomy. This study aimed to assess the use of preoperative MRI in predicting pathological changes of the gallbladder associated with surgical difficulty. METHODS: Patients who underwent both preoperative MRI and early cholecystectomy for acute cholecystitis between 2012 and 2018 were identified retrospectively. On the basis of the layered pattern of the gallbladder wall on MRI, patients were classified into three groups: high signal intensity (HSI), intermediate signal intensity (ISI), and low signal intensity (LSI). The endpoint was the presence of pathological changes of the gallbladder associated with surgical difficulty, such as necrosis, abscess formation and fibrosis. RESULTS: Of 229 eligible patients, pathological changes associated with surgical difficulty were found in 17 (27 per cent) of 62 patients in the HSI group, 84 (85 per cent) of 99 patients in the ISI group, and 66 (97 per cent) of 68 patients in the LSI group (P < 0·001). For detecting these changes, intermediate to low signal intensity of the gallbladder wall had a sensitivity of 90 (95 per cent c.i. 84 to 94) per cent, specificity of 73 (60 to 83) per cent and accuracy of 85 (80 to 90) per cent. CONCLUSION: Preoperative MRI predicted pathological changes associated with surgical difficulty during laparoscopic cholecystectomy for acute cholecystitis.

ANTECEDENTES: La inflamación grave con necrosis y fibrosis de la vesícula biliar en la colecistitis aguda aumenta la dificultad quirúrgica durante la colecistectomía laparoscópica. Este estudio tuvo como objetivo evaluar el uso de la resonancia magnética preoperatoria (magnetic resonance imaging, MRI) para predecir los cambios patológicos de la vesícula biliar asociados con la dificultad quirúrgica. MÉTODOS: Los pacientes que se sometieron tanto a MRI preoperatoria como a colecistectomía precoz por colecistitis aguda entre 2012 y 2018 fueron identificados retrospectivamente. En base a la distribución en capas de la pared de la vesícula biliar en la MRI, los pacientes se clasificaron en tres grupos: (1) intensidad de señal alta (high signal intensity, HSI), (2) intensidad de señal intermedia (intermediate signal intensity, ISI) y (3) intensidad de señal baja (low signal intensity, LSI). El objetivo final fue la presencia de cambios patológicos en la vesícula biliar asociados con la dificultad quirúrgica, tales como necrosis, formación de abscesos y fibrosis. RESULTADOS: De los 229 pacientes elegibles, se documentaron cambios patológicos asociados con dificultad quirúrgica en 17 (27,4%) de 62 pacientes en el grupo HSI, 84 (84,8%) de 99 pacientes en el grupo ISI y 66 (97,1%) de 68 pacientes en el grupo LSI (P < 0,001). Para detectar estos cambios, la intensidad de señal de intermedia a baja de la pared de la vesícula biliar tuvo una sensibilidad del 89,8% (i.c. del 95% 84,2%-94,0%), una especificidad del 72.6% (i.c. del 95% 59,8%-83,1%) y una precisión del 85,2% (i.c. del 95% 79,9%-89,5%). CONCLUSIÓN: La MRI preoperatoria predijo los cambios patológicos asociados con la dificultad quirúrgica durante la colecistectomía laparoscópica por colecistitis aguda.

Efficacy of dimethyl fumarate in Japanese multiple sclerosis patients: interim analysis of randomized, double-blind APEX study and its open-label extension.

BACKGROUND: Current data for the use of dimethyl fumarate (DMF) in Japanese patients with relapsing-remitting multiple sclerosis (RRMS) is limited. OBJECTIVES: To assess the efficacy of DMF in Japanese patients with RRMS. METHODS: The phase 3, multinational APEX study (ClinicalTrials.gov identifier: NCT01838668) consisted of two parts: a 24-week double-blind part where subjects were randomized to receive DMF 240 mg or placebo twice daily in East Asian and Eastern European countries, and an open-label extension part where all subjects received DMF. The primary endpoint was the total number of new gadolinium-enhancing lesions in Weeks 12-24. In this interim analysis, we report efficacy data in the Japanese subgroup (DMF n = 56; placebo n = 58) over 72 weeks, including an extension phase. RESULTS: DMF reduced the total number of new gadolinium-enhancing lesions in Weeks 12-24 by 85% versus placebo (p < 0.0001). At Week 24, the annualized relapse rate was also reduced by 48% with DMF, versus placebo. DMF reduced the probability of relapse from Week 8 and was sustained. The number of gadolinium-enhancing lesions was maintained through 72 weeks. CONCLUSIONS: DMF demonstrated sustained efficacy in this Japanese subgroup. The results were consistent with those observed in studies of DMF enrolling primarily Caucasian patients.

Randomized clinical trial of single skin sterilization with a povidone-iodine applicator versus conventional skin sterilization in abdominal surgery.

Background: The efficacy of widely used povidone-iodine applicators for skin sterilization in abdominal surgery is unclear. The aim of this trial was to evaluate whether sterilization with a povidone-iodine applicator was not inferior to a conventional sterilization method. Methods: Patients undergoing elective abdominal surgery were assigned randomly to receive single sterilization with the applicator or conventional sterilization. The primary endpoint was wound infection rate. Secondary endpoints were rate of organ/space surgical-site infection (SSI), adverse effects of povidone-iodine, amount of povidone-iodine used and total cost of sterilization. Results: Of 498 patients eligible for the study between April 2015 and September 2017, 240 were assigned and analysed in the applicator group and 246 in the conventional group. Wound infection was detected in 16 patients (6·7 per cent) in the applicator group and 16 (6·5 per cent) in the conventional group (absolute difference 0·0016 (90 per cent c.i. -0·037 to 0·040) per cent; P = 0·014 for non-inferiority). There was no difference between the groups in the organ/space SSI rate (11 patients (4·6 per cent) in the applicator group and 16 (6·5 per cent) in the conventional group. Both the amount of povidone-iodine used and the total cost of sterilization were higher in the conventional group than in the applicator group (median 76·7 versus 25 ml respectively, P < 0·001; median €7·0 versus €6·4, P < 0·001). Skin irritation was detected in three patients in the conventional group. Conclusion: In abdominal surgery, this povidone-iodine applicator was not inferior to conventional sterilization in terms of the wound infection rate, and it is cheaper. Registration number: UMIN000018231 (http://www.umin.ac.jp/ctr/).

Comparison between dexmedetomidine and midazolam as a sedation agent with local anesthesia in inguinal hernia repair: randomized controlled trial.

PURPOSE: In Japan, inguinal hernia repair is widely performed with local anesthesia. The objective of this study was to evaluate safety and efficacy of intravenous dexmedetomidine as a sedation agent with local anesthesia in inguinal hernia repair. METHODS: We performed this randomized, single-blind study for 200 patients who were scheduled to undergo inguinal hernia repair with local anesthesia. Patients were randomly divided into two groups (dexmedetomidine group: Group D, midazolam group: Group M). The primary outcome was to evaluate the safety of intravenous dexmedetomidine. Secondary outcomes were to analyze results of operators' surveys and patients' questionnaires and evaluate implementation of conscious sedation. RESULTS: Incidence of respiratory depression was significantly higher in Group M than Group D (p = 0.03). Other adverse events examined did not differ significantly. All three operators' questionnaires indicated that results were better in Group D than Group M. More than 70% of patients in both groups were satisfied with the surgery. More than 80% of Group D patients and 74% of Group M patients achieved a state of conscious sedation. CONCLUSION: This study demonstrated that intravenous dexmedetomidine during hernia repair with local anesthesia is safe and the results were satisfactory to both operators and patients.

The development of Weinstein's noise sensitivity scale.

Many studies have shown the significant correlation between noise annoyance and noise sensitivity identified by Weinstein's noise sensitivity scale (WNS). However, the validity of the scale has not been sufficiently assessed. This study was designed to investigate the validity of each question in WNS and to develop a more valid noise sensitivity measurement scale. A questionnaire study was conducted in a residential area along trunk roads in Kusatsu, Japan, and 301 responses were collected. In this paper, noise sensitivity was defined as the factor that induced individual variability in reactions caused by noise exposure and that is not affected by the noise exposure. The relationship between noise exposure and answers to each question in WNS was investigated by multiple logistic regression analysis, and the influence of response bias on the score of WNS was examined. The results showed that WNS contained some questions that were inappropriately related to noise exposure level and that the score was affected by response bias. The reported correlation between annoyance and the score of WNS could be confounded by noise exposure and response bias. A noise sensitivity measurement scale named WNS-6B was newly developed, excluding the biased questions from the original WNS and applying binary coding to six-response options in order to reduce the response bias. WNS-6B seemed to be more appropriate to assess noise sensitivity than the original scale.

Growth inhibition of human lung cancer cell lines by interleukin 6 in vitro: a possible role in tumor growth via an autocrine mechanism.

It has been considered that growth of human lung cancer cells, like other malignant cells, is positively and negatively regulated by a variety of growth factors via autocrine as well as paracrine mechanisms. The autocrine mechanism is considered to be important in the autonomy of proliferation of cancer cells. Recently, the role of autocrine growth-inhibiting factors such as transforming growth factor beta attracts special attention for better understanding of growth regulation of malignant cells. Here, we have demonstrated that a multifunctional cytokine interleukin 6 (IL-6) had an inhibitory effect on the proliferation of human non-small cell lung cancer cell lines, as shown by the growth accelerating effect of the specific anti-IL-6 antibody as well as the effect of exogenously added IL-6. Moreover, IL-6 can be expressed and released by human lung cancer cells, and these cells had specific IL-6 receptors on their cell surfaces, suggesting an autocrine mechanism. The growth-inhibitory effect of IL-6 was additive to that of transforming growth factor beta, and could not be neutralized by the addition of anti-transforming growth factor beta antibody. These results suggested that IL-6 may function as another class of autocrine growth-inhibiting factor in the growth regulation of human lung cancer. Relatively lower IL-6 sensitivity of these cells than noncarcinogenic human bronchial epithelial cells also suggested that escape from growth regulation by inhibitory factors such as IL-6 could be involved in lung cancer oncogenesis.

[Evaluation of aortic valve replacement involving small severely calcified aortic annulus in elderly patients].

We performed aortic valve replacement in 24 patients aged over 70 with small calcified valves. The surgical management of such patients remains controversial as the extensive calcification compromises implantation. Hence, we used an ultrasonic debridement instrument to remove calcium and selected a small prosthesis with the largest possible orifice without enlargement of the aortic annulus. Echocardiography showed significant reductions in left ventricular mass index compared with preoperative values. Early and mid-term prognosis has been relatively good.

Dynamics of L cells along the crypt-villous axis in the chicken ileum.

The dynamics of L cells along the crypt-villous axis were investigated in the ileum of male White Leghorn chicks (7 d of age, n = 5). Immunohistochemistry was used to detect the expression of glucagon-like peptide (GLP)-1 and an in situ hybridization technique to detect proglucagon messenger RNA (mRNA). Immunocytochemistry using colloidal gold was also applied to quantitatively evaluate the GLP-1 content. The cells expressing a proglucagon mRNA signal were distributed mainly in the crypts and the bottom of the villi but were never found in the upper part of the villi. Most of the cells expressing a proglucagon mRNA signal (97%) were immunoreactive for GLP-1 antiserum. In contrast, GLP-1 immunoreactive cells were distributed from the crypts to the middle part of the villi, and only 55% of them expressed a proglucagon mRNA signal. Quantitative evaluation by immunocytochemistry of GLP-1 using colloidal gold revealed that the GLP-1 content was significantly lower in L cells located in the villous epithelium than that of L cells located in the crypts (P < 0.01). These findings indicate that L cells in the chicken ileum mature and complete GLP-1 production in the crypts. L cells in the villous epithelium secrete GLP-1 but do not synthesize this peptide.

Early results of multicenter phase II trial of perioperative oxaliplatin and capecitabine without radiotherapy for high-risk rectal cancer: CORONA I study.

BACKGROUNDS: Perioperative introduction of developed chemotherapy into the treatment strategy for locally advanced rectal cancer (LARC) may be a promising option. However, the most prevalent treatment for high-risk LARC remains preoperative chemoradiotherapy (CRT) in Western countries. PATIENTS AND METHODS: A phase II trial was undertaken to evaluate safety and efficacy of perioperative XELOX without radiotherapy (RT) for patients with high-risk LARC. Patients received 4 cycles of XELOX before and after surgery, respectively. Primary endpoint was disease-free survival. RESULTS: We enrolled 41 patients between June 2012 and April 2014. The completion rate of the preoperative XELOX was 90.3%. Twenty-nine patients (70.7%) could start postoperative XELOX, 15 of these patients (51.7%) completed 4 cycles. Allergic reaction to oxaliplatin was experienced by 5 patients (17.2%) during postoperative XELOX. One patient received additional RT after preoperative XELOX. Consequently, the remaining 40 patients underwent primary resection. Major complications occurred in 6 of 40 patients (15.0%). Pathological complete response (pCR) rate was 12.2%, and good tumor regression was exhibited in 31.7%. N down-staging (cN+ to ypN0) and T down-staging were detected in 56.7% and 52.5%, respectively. Clinical T4 tumor was a predictor of poor pathological response (p < 0.001). CONCLUSIONS: We could show the favorable pCR rate after preoperative XELOX alone. However, the T and N down-staging rate was likely to be insufficient. When tumor regression is essential for curative resection, the use of preoperative CRT is likely to be recommended. For patients with massive LN metastasis, the additional Bev to NAC might be a promising option.

The emergence and evolution of methicillin-resistant Staphylococcus aureus.

Significant advances have been made in recent years in our understanding of how methicillin resistance is acquired by Staphylococcus aureus. Integration of a staphylococcal cassette chromosome mec (SCCmec) element into the chromosome converts drug-sensitive S. aureus into the notorious hospital pathogen methicilin-resistant S. aureus (MRSA), which is resistant to practically all beta-lactam antibiotics. SCCmec is a novel class of mobile genetic element that is composed of the mec gene complex encoding methicillin resistance and the ccr gene complex that encodes recombinases responsible for its mobility. These elements also carry various resistance genes for non-beta-lactam antibiotics. After acquiring an SCCmec element, MRSA undergoes several mutational events and evolves into the most difficult-to-treat pathogen in hospitals, against which all extant antibiotics including vancomycin are ineffective. Recent epidemiological data imply that MRSA has embarked on another evolutionary path as a community pathogen, as at least one novel SCCmec element seems to have been successful in converting S. aureus strains from the normal human flora into MRSA.

Cleavage of the S-S bond in 5,5'-dithiobis-(2-nitrobenzoic acid) in the presence of a cationic detergent: an approach to the cleavage of the S-S bond in bovine plasma albumin.

The hydrolysis of 5,5'-dithiobis-(2-nitrobenzoic acid) was studied at pH 9.20 and 25 degrees C in presence of tetradecyltrimethylammonium bromide or micellar tetradecyltrimethylammonium bromide. The reaction was pseudo-unimolecular reaction with regard to the concentration of dithionitrobenzoic acid. The rate constant k1 depended on the tetradecyltrimethylammonium bromide concentration and on the ionic strength of the buffer solution. At a constant ionic strength, the value of k1 increased with the increase in the tetradecyltrimethylammonium bromide concentration, attained maximum at a certain concentration above the critical micelle concentration, and then decreased. The value of k1 was larger when the ionic strength was lower. The rate of hydrolysis at the ionic strength 0.1 was the same as that without tetradecyltrimethylammonium bromide. On the contrary, sodium dodecyl sulfate or micellar sodium dodecyl sulfate had no effect on the rate of hydrolysis. These results lead to the conclusion that the S-S bond is cleaved easier, when it is surrounded by the cationic detergent. The SH/S-S exchange reaction of bovine plasma albumin in the presence of cationic detergent was slower when the ionic strength was higher. The fact could be explained by assuming that the exposed S-S bond is surrounded by the cationic detergent. Further, it was speculated that some S-S bonds in albumin are surrounded by the positively charged basic amino acid residues.

Cooperative binding of hexadecyltrimethylammonium chloride and sodium dodecyl sulfate to cytochrome c and the resultant change in protein conformation.

The binding of hexadecyltrimethylammonium chloride (HTAC) and sodium dodecyl sulfate (SDS) to cytochrome c was determined by potentiometric titration and the corresponding changes in protein conformation by circular dichroism (CD). The binding isotherms were biphasic; about 20 surfactant cations or anions were bound to cytochrome c in the first phase. Another 30 or so HTA+ ions were bound in the second phase, which was below the critical micelle concentration of the surfactant, but the binding of dodecyl sulfate ions in the second phase increased sharply near the critical micelle concentration. The binding of both surfactants was highly cooperative and was endothermic; the data in the first phase fitted the Hill plot. The corresponding change in the secondary structure of cytochrome c was small; the CD spectra in the ultraviolet region showed a moderate increase in the helicity in HTAC solution and some changes in conformation in SDS solution. However, the CD spectra for the Soret band indicated a marked change in the local conformation around the heme.