Angiographic factors associated with haemorrhagic presentation of brain arteriovenous malformation in a Chinese paediatric population.

OBJECTIVE: To identify specific angiographic factors associated with haemorrhagic presentation of brain arteriovenous malformation in Chinese paediatric patients. DESIGN: Retrospective cross-sectional observational study. SETTING: Four locoregional tertiary neurosurgical centres in Hong Kong: Queen Elizabeth Hospital, Tuen Mun Hospital, Kwong Wah Hospital, and Pamela Youde Nethersole Eastern Hospital. PATIENTS: Patients aged 18 years or younger who underwent pretreatment digital subtraction angiography for brain arteriovenous malformation between 1 January 2005 and 31 July 2013 were included. Patients were divided into haemorrhagic and non-haemorrhagic groups based on the initial presentation. Pretreatment digital subtraction angiographies were independently reviewed by two experienced neuroradiologists. MAIN OUTCOME MEASURES: The following parameters were evaluated for their association with haemorrhagic presentation by univariate and multivariate analyses: nidus location, nidus size, nidus morphology (diffuse or compact); origin and number of arterial feeders; venous drainage; number of draining veins; presence of aneurysms, venous varices, and venous stenosis. RESULTS: A total of 67 children and adolescents (28 male, 39 female) with a mean age of 12 years were included. Of them, 52 (78%) presented with haemorrhage. Arteriovenous malformation size (P=0.004) and morphology (P=0.05) were found to be associated with haemorrhagic presentation by univariate analysis. Small arteriovenous malformation nidus size and diffuse nidal morphology were identified as independent risk factors for haemorrhage by multivariate analysis. CONCLUSION: Smaller arteriovenous malformation size and diffuse nidal morphology are angiographic factors independently associated with haemorrhagic presentation. Bleeding risk is important in determining the therapeutic approach (aggressive vs conservative) and timeframe, particularly in paediatric patients.

Endovascular stenting in the management of malignant superior vena cava obstruction: comparing safety, effectiveness, and outcomes between primary stenting and salvage stenting.

OBJECTIVE: To compare the safety, effectiveness, and outcomes of primary stenting and salvage stenting for malignant superior vena cava obstruction. DESIGN: Case series with internal comparison. SETTING: Regional hospital, Hong Kong. PATIENTS: A total of 56 patients with malignant superior vena cava obstruction underwent 59 stentings from 1 May 1999 to 31 January 2014. Patients' characteristics, procedural details, and outcomes were retrospectively reviewed. Of the 56 patients, 33 had primary stenting before conventional therapy and 23 had salvage stenting after failure of conventional therapy. Statistical analyses were made by Fisher's exact test and Mann-Whitney U test. RESULTS: Primary lung carcinoma was the most common cause of malignant superior vena cava obstruction (primary stenting, 22 patients; salvage stenting, 16 patients; P=0.768), followed by metastatic lymphadenopathy. Most patients had superior vena cava obstruction only (primary stenting, 16 patients; salvage stenting, 15 patients; P=0.633), followed by additional right brachiocephalic vein involvement. Wallstents (Boston Scientific, Natick [MA], US) were used in all patients. Technical success was achieved in all but two patients, one in each group (P=1.000). Only one stent placement was required in most patients (primary stenting, 28 patients; salvage stenting, 20 patients; P=0.726). Procedure time was comparable in both groups (mean time: primary stenting, 89 minutes; salvage stenting, 84 minutes; P=0.526). Symptomatic relief was achieved in most patients (primary stenting, 32 patients; salvage stenting, 23 patients; P=0.639). In-stent restenosis and bleeding were the commonest complications (primary stenting, 6 and 1 patients, respectively; salvage stenting, 2 and 2 patients, respectively). Nine patients required further treatment for symptom recurrence (primary stenting, 6 patients; salvage stenting, 3 patients; P=0.725). CONCLUSION: Endovascular stenting is safe and effective for relieving malignant superior vena cava obstruction. No statistically significant differences in number of stents, success rates, procedure times, symptom relief rates, complication rates, and re-procedure rates were found between primary stenting and salvage stenting.

Performance of the VITEK MS matrix-assisted laser desorption ionization-time of flight mass spectrometry system for rapid bacterial identification in two diagnostic centres in China.

Matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) MS systems was not officially launched for diagnostic use in clinical microbiology laboratories in China until 2012. Here, we report the findings from the first large-scale evaluation study of VITEK MS for routine bacterial identification in two major diagnostic centres in Beijing and Hong Kong. A total of 2266 unique isolates representing 56 genera and 127 species were analysed, and results were compared to those obtained by VITEK 2. Any discrepancies were resolved by 16S rRNA sequencing. Overall, VITEK MS provided correct identification for 2246 (99.1%) isolates, including 2193 (96.8 %) with correct species-level identifications and 53 (2.3 %) matched at the genus level only. VITEK MS surpassed VITEK 2 consistently in species-level identification of important pathogens, including non-Enterobacteriaceae Gram-negative bacilli (94.7 versus 92 %), staphylococci (99.7 versus 92.4 %), streptococci (92.6 versus 79.4 %), enterococci (98.8 versus 92.6 %) and Clostridium spp. (97.3 versus 55.5 %). The findings demonstrated that VITEK MS is highly accurate and reliable for routine bacterial identification in clinical settings in China.

Ginsenoside Rb1 inhibits tube-like structure formation of endothelial cells by regulating pigment epithelium-derived factor through the oestrogen beta receptor.

BACKGROUND AND PURPOSE: Angiogenesis is a crucial step in tumour growth and metastasis. Ginsenoside-Rb1 (Rb1), the major active constituent of ginseng, potently inhibits angiogenesis in vivo and in vitro. However, the underlying mechanism remains unknown. We hypothesized that the potent anti-angiogenic protein, pigment epithelium-derived factor (PEDF), is involved in regulating the anti-angiogenic effects of Rb1. EXPERIMENTAL APPROACHES: Rb1-induced PEDF was determined by real-time PCR and western blot analysis. The anti-angiogenic effects of Rb1 were demonstrated using endothelial cell tube formation assay. Competitive ligand-binding and reporter gene assays were employed to indicate the interaction between Rb1 and the oestrogen receptor (ER). KEY RESULTS: Rb1 significantly increased the transcription, protein expression and secretion of PEDF. Targeted inhibition of PEDF completely prevented Rb1-induced inhibition of endothelial tube formation, suggesting that the anti-angiogenic effect of Rb1 was PEDF specific. Interestingly, the activation of PEDF occurred via a genomic pathway of ERbeta. Competitive ligand-binding assays indicated that Rb1 is a specific agonist of ERbeta, but not ERalpha. Rb1 effectively recruited transcriptional activators and activated an oestrogen-responsive reporter gene. Furthermore, Rb1-mediated PEDF activation and the subsequent inhibition of tube formation were blocked by the ER antagonist ICI 182,780 or transfection of ERbeta siRNA, indicating ERbeta dependence. CONCLUSIONS AND IMPLICATIONS: Here we show for the first time that the Rb1 suppressed the formation of endothelial tube-like structures through modulation of PEDF via ERbeta. These findings demonstrate a novel mechanism of the action of this ginsenoside that may have value in anti-cancer and anti-angiogenesis therapy.

Angiomodulatory and neurological effects of ginsenosides.

Panax ginseng C.A. Meyer, one of the most popular and valued herbs, has been used extensively in traditional Chinese medicine for thousands of years. More than thirty ginsenosides, the pharmacologically active ingredients in ginseng, have been identified with various sugar moieties attached at the C-3, C-6 and C-20 positions of the steroidal skeleton. We herein review the current literature on the pharmacological effects of ginsenosides on the modulation of angiogenesis, dysregulations of which contribute towards many pathological conditions. Regarding the adaptogenic property of ginseng, the effects of ginsenosides on central nervous system are also discussed. Recent researches have pointed to the steroid hormone receptors as the target molecules to elicit the diverse cellular and physiological activities of ginseng. We believe that understanding the interaction between ginsenosides and various steroid hormone receptors may provide clues to unravel the secret of ginseng.

Disease progression in Chinese chronic hepatitis C patients with persistently normal alanine aminotransaminase levels.

BACKGROUND: Although chronic hepatitis C virus-infected patients with persistently normal alanine aminotransaminase levels usually have mild liver disease, disease progression can still occur. However, it is uncertain which group of patients is at risk of disease progression. AIM: To examine the severity of liver disease on liver biopsy in Chinese patients with persistently normal alanine aminotransaminase levels, and their disease progression over time. METHODS: Eighty-two patients with persistently normal alanine aminotransaminase levels were followed up longitudinally. The median time of follow-up was 8.1 years. Forty-seven of the 82 patients (57.3%) had a second liver biopsy. RESULTS: At the time of analysis, six of the 82 patients (7.3%) developed decompensated liver cirrhosis. Patients with an initial fibrosis stage F2 or F3 [6/23 (26.1%) vs. 0/59 (0%), P < 0.0001] or inflammatory grade A2 or A3 [5/40 (12.5%) vs. 1/42 (2.4%), P = 0.04] were more likely to develop decompensated liver cirrhosis. On multivariate analysis, initial fibrosis stage F2 or F3 was independently associated with progression to decompensated liver cirrhosis (relative risk 2.3, 95% confidence interval 0.03-2.5, P = 0.02). CONCLUSION: Chinese chronic hepatitis C virus patients with persistently normal alanine aminotransaminase levels with moderate to severe fibrosis at initial evaluation are more likely to develop decompensated liver cirrhosis.

Neuroprotective effects of ginsenoside-Rg1 in primary nigral neurons against rotenone toxicity.

Ginsenoside-Rg1, the pharmacologically active component isolated from ginseng, demonstrated neuroprotective effects on primary cultured rat nigral neurons against rotenone toxicity. Rotenone, a common household pesticide known for its specific and irreversible mitochondria complex I inhibition, has been suggested to be the causal agent of Parkinson's disease (PD) by inducing degeneration of cells in the substantial nigra. The present study demonstrated that co-treatment of rotenone and Rg1 could reduce rotenone-induced cell death by 58% (SEM=+/-5.60; N=3). Rotenone-induced mitochondria membrane potential (MMP, DeltaPsim) depletion was restored and elevated by at least 38% (SEM=+/-2.15; N=3) by Rg1. In addition, Rg1 prevented cytochrome c release from the mitochrondrial membrane and increased the phosphorylation inhibition of the pro-apoptotic protein Bad through activation of the PI3K/Akt pathway. The protective effects of Rg1 was blocked by glucocorticoid receptor antagonist RU486, indicating that the action of Rg1 is mediated through glucocorticoid receptor (GR). In conclusion, Rg1 inhibits the mitochondrial apoptotic pathway and increases the survival chance of the primary cultured nigral neurons against rotenone toxicity. Thus, Rg1 and its related compounds may be developed as protective agents against neurodegenerative diseases induced by mitochondrial toxins.

Globicatella bacteraemia identified by 16S ribosomal RNA gene sequencing.

BACKGROUND: Globicatella are streptococcus-like organisms that have been rarely isolated from clinical specimens. Their epidemiology and clinical significance remain largely unknown. AIMS: To describe two cases of Globicatella bacteraemia identified by 16S ribosomal RNA (rRNA) gene sequencing. METHODS: Two unidentified streptococcus-like bacteria isolated from blood cultures of patients were subject to 16S rRNA gene sequencing. RESULTS: Two cases of Globicatella bacteraemia were identified by 16S rRNA gene sequencing. In the first case, a gram positive coccus was isolated from the blood culture of an 80 year old woman with diabetes mellitus and nosocomial sepsis, who died the day after developing the bacteraemia. The bacterium was unidentified by conventional phenotypic tests, the Vitek (gram positive identification) and the ATB expression (ID32 Strep) systems. In the second case, a similar bacterium was isolated from the blood culture of a 92 year old woman with polymicrobial acute pyelonephritis complicated by septic shock, who subsequently recovered after antibiotic treatment. 16S rRNA gene sequencing of the two isolates showed 0.5% nucleotide difference from that of G. sulfidifaciens and 0.7% nucleotide difference from that of G. sanguinis, indicating that they were Globicatella species. CONCLUSIONS: Because Globicatella is rarely encountered in clinical microbiology laboratories, it may have been overlooked or misidentified in these cases. 16S rRNA gene sequencing is a useful tool to better characterise the epidemiology and clinical significance of Globicatella.

Aging and mfERG topography.

AIM: To study the effect of aging retina on the multifocal electroretinogram (mfERG). METHODS: A total of 18 young subjects (age 18-24 years) and 36 elderly subjects (aged 60-85 years) with intraocular lenses (IOLs) were recruited for this study. No subjects had significant eye diseases or media opacities. mfERG was measured in standard conditions using the VERIS system (version 4.1). There were three groups of 18 subjects: (1) 18-25 years, (2) 60-70 years, and (3) 75-85 years. mfERG responses were grouped into central, paracentral, and peripheral regions for analysis. The N1 amplitude, P1 amplitude, N1 latency, and P1 latency of the first-order responses were analysed. RESULTS: Age had no effect on P1 latency, N1 amplitude, and P1 amplitude; however, N1 latencies from central to peripheral regions were significantly longer for group 3 than for group 1. CONCLUSIONS: This study suggests that measured age-related decreases in mfERG responses are due to optical factors (decrease in retinal light levels, scatter) before the age of 70 years, but neural factors significantly affect mfERG topography after the age of 70 years.

Orthogonal array design in optimizing the extraction efficiency of active constituents from roots of Panax notoginseng.

The root of Panax notoginseng (Radix Notoginseng, Sanqi) is a commonly used traditional Chinese medicine, which is mainly cultivated in Wenshan of Yunnan China. The identified active constituents in Radix Notoginseng include saponin, ssavonoid and polysaccharide; however, the levels of these active constituents vary greatly with different extraction processes. This variation causes a serious problem in standardizing the herbal extract. By using HPLC and spectrophotometry, the contents of notoginsenoside R(1), ginsenoside R(g1), R(b1), R(d), and ssavonoids were determined in the extracts of Radix Notoginseng that were derived from different processes of extraction according to an orthogonal array experimental design having three variable parameters: nature of extraction solvent, extraction volume and extraction time. The nature of extraction solvent and extraction volume were two distinct factors in obtaining those active constituents, while the time of extraction was a subordinate factor. The optimized condition of extraction therefore is considered to be 20 volumes of water and extracted for 24 h. In good agreement with the amount of active constituents, the activity of anti-platelet aggregation was found to be the highest in the extract that contained a better yield of the active constituents. The current results provide an optimized extraction method for the quality control of Radix Notoginseng.

Severe acute respiratory syndrome (SARS) and the GDP. Part II: implications for GDPs.

The transmission modes of SARS-coronavirus appear to be through droplet spread, close contact and fomites although air borne transmission has not been ruled out. This clearly places dental personnel at risks as they work in close proximity to their patients employing droplet and aerosol generating procedures. Although the principle of universal precautions is widely advocated and followed throughout the dental community, additional precautionary measures - termed standard precaution may be necessary to help control the spread of this highly contagious disease. Patient assessment should include questions on recent travel to SARS infected areas and, contacts of patients, fever and symptoms of respiratory infections. Special management protocols and modified measures that regulate droplet and aerosol contamination in a dental setting have to be introduced and may include the reduction or avoidance of droplet/aerosol generation, the disinfection of the treatment field, application of rubber dam, pre-procedural antiseptic mouthrinse and the dilution and efficient removal of contaminated ambient air. The gag, cough or vomiting reflexes that lead to the generation of aerosols should also be prevented.

Severe Acute Respiratory Syndrome (SARS) and the GDP. Part I : Epidemiology, virology, pathology and general health issues.

The health profession faces a new challenge with the emergence of a novel viral disease Severe Acute Respiratory Syndrome (SARS), a form of atypical pneumonia caused by a coronavirus termed SARS-CoV. This highly infectious disease has spread through 32 countries, infecting more than 8,400 patients with over 790 deaths in just over 6 months. Over one quarter of those infected were unsuspecting healthcare workers. The major transmission mode of SARS-coronavirus appears to be through droplet spread with other minor subsidiary modes of transmission such as close contact and fomites although air borne transmission has not been ruled out. There is as yet no definitive treatment protocol. Although the peak period of the outbreak is likely to have passed and the risk of SARS in the UK is therefore assessed to be low, the World Health Organisation has asked all countries to remain vigilant lest SARS re-emerges. Recent laboratory acquired cases of SARS reported from Taiwan and Beijing, China are a testimony to this risk. Until reliable diagnostic tests, vaccine and medications are available, control of SARS outbreaks depends on close surveillance, early identification of index cases, quick isolation of carriers and effective infection control and public health measures.

Pseudobacteraemia in a patient with neutropenic fever caused by a novel paenibacillus species: Paenibacillus hongkongensis sp. nov.

AIMS: To characterise a strain of Gram negative aerobic straight or slightly curved rods (HKU3) isolated from the blood culture of a 9 year old Chinese boy with neutropenic fever and pseudobacteraemia. METHODS: The isolate was phenotypically investigated by standard biochemical methods using conventional biochemical tests, scanning electron microscopy, and transmission electron microscopy. Genotypically, the 16S rRNA gene of the bacterium was amplified by the polymerase chain reaction (PCR) and sequenced. The sequence of the PCR product was compared with known 16S rRNA gene sequences in the Genbank by multiple sequence alignment. The G + C content was determined by thermal denaturation. A phylogenetic tree was constructed by the PileUp method. RESULTS: The cells of the bacterial strain were aerobic, sporulating, Gram negative straight or slight curved rods. The bacterium grew on horse blood agar as non-haemolytic, grey colonies of 1 mm in diameter after 24 hours of incubation at 37 degrees C in ambient air. No enhancement of growth was seen in 5% CO(2). It grew at 50 degrees C as pinpoint colonies after 72 hours of incubation, but did not grow at 65 degrees C or on MacConkey agar. It was non-motile. It produced catalase (weakly positive) and cytochrome oxidase. It reduced nitrate, produced beta galactosidase, hydrolysed esculin, and utilised sodium acetate. A scanning electron micrograph of the bacterium showed straight or slightly curved rods. A transmission electron micrograph of the cell wall of the bacterium revealed multiple electron dense layers, including the outer membrane, middle murein layer, and inner cytoplasmic membrane, compatible with its Gram smear appearance. 16S rRNA gene sequencing showed that there were 7.7%, 8.0%, 8.2%, and 8.6% differences between the 16S rRNA gene sequence of the bacterium and those of Paenibacillus macerans, Paenibacillus borealis, Bacillus ehimensis, and Paenibacillus amylolyticus, respectively. The mean (SD) G + C content of the bacterium was 47.6 (2.1) mol%. Phylogenetically, it belongs to the genus paenibacillus (previously called group 3 bacillus). CONCLUSIONS: A bacterium that exhibited phenotypic and genotypic characteristics that are very different from closely related members of paenibacillus was the cause of pseudobacteraemia in a patient with neutropenic fever. A new species, Paenibacillus hongkongensis sp. nov. is proposed, for which HKU3 is the type strain.

Identification by 16S ribosomal RNA gene sequencing of Arcobacter butzleri bacteraemia in a patient with acute gangrenous appendicitis.

AIMS: To identify a strain of Gram negative facultative anaerobic curved bacillus, concomitantly isolated with Escherichia coli and Streptococcus milleri, from the blood culture of a 69 year old woman with acute gangrenous appendicitis. The literature on arcobacter bacteraemia and arcobacter infections associated with appendicitis was reviewed. METHODS: The isolate was phenotypically investigated by standard biochemical methods using conventional biochemical tests. Genotypically, the 16S ribosomal RNA (rRNA) gene of the bacterium was amplified by the polymerase chain reaction (PCR) and sequenced. The sequence of the PCR product was compared with known 16S rRNA gene sequences in the GenBank by multiple sequence alignment. Literature review was performed by MEDLINE search (1966-2000). RESULTS: The bacterium grew on blood agar, chocolate agar, and MacConkey agar to sizes of 1 mm in diameter after 24 hours of incubation at 37 degrees C in 5% CO2. It grew at 15 degrees C, 25 degrees C, and 37 degrees C; it also grew in a microaerophilic environment, and was cytochrome oxidase positive and motile, typically a member of the genus arcobacter. Furthermore, phenotypic testing showed that the biochemical profile of the isolate did not fit into the pattern of any of the known arcobacter species. 16S rRNA gene sequencing showed one to two base differences between the isolate and A butzleri, but 35 to 39 base differences between the isolate and A cryaerophilus, indicating that the isolate was a strain of A butzleri. Only three cases of arcobacter bacteraemia with detailed clinical characteristics were found in the English literature. The sources of the arcobacter species in the three cases were largely unknown, although the gastrointestinal tract is probably the portal of entry of the A butzleri isolated from the present case because the two concomitant isolates (E coli and S milleri) in the blood culture were common flora of the gastrointestinal tract. In addition, A butzleri has previously been isolated from the abdominal contents or peritoneal fluid of three patients with acute appendicitis. CONCLUSIONS: 16S rRNA gene sequencing was useful in the identification of the strain of A butzleri isolated from the blood culture of a patient with acute gangrenous appendicitis. Arcobacter bacteraemia is rare. Further studies using selective medium for the delineation of the association between A butzleri and acute appendicitis are warranted.

Emergence of cotrimoxazole- and quinolone-resistant Campylobacter infections in bone marrow transplant recipients.

Clinical and microbiological data were collected prospectively from 704 patients who underwent bone marrow transplantation (BMT) during an 11-year period (1991-2001), and the first two cases of Campylobacter infection occurring in BMT recipients in the pre-engraftment period were identified. The two cases occurred on days 2 and 3 post-BMT, respectively. Both patients had Campylobacter jejuni enteritis, and one case was complicated by bacteraemia. In both cases the presenting symptoms were indistinguishable from hospital-acquired pre-engraftment diarrhoea, which is commonly caused by Clostridium difficile. Both of the Campylobacter jejuni isolates were resistant to cotrimoxazole and ciprofloxacin. Both patients responded to intravenous meropenem and subsequently had uneventful marrow engraftment.

Laribacter hongkongensis gen. nov., sp. nov., a novel gram-negative bacterium isolated from a cirrhotic patient with bacteremia and empyema.

A bacterium was isolated from the blood and empyema of a cirrhotic patient. The cells were facultatively anaerobic, nonsporulating, gram-negative, seagull shaped or spiral rods. The bacterium grows on sheep blood agar as nonhemolytic, gray colonies 1 mm in diameter after 24 h of incubation at 37 degrees C in ambient air. Growth also occurs on MacConkey agar and at 25 and 42 degrees C but not at 4, 44, and 50 degrees C. The bacterium can grow in 1 or 2% but not 3, 4, or 5% NaCl. No enhancement of growth is observed with 5% CO(2). The organism is aflagellated and nonmotile at both 25 and 37 degrees C. It is oxidase, catalase, urease, and arginine dihydrolase positive, and it reduces nitrate. It does not ferment, oxidize, or assimilate any sugar tested. 16S rRNA gene sequencing showed that there are 91 base differences (6.2%), 112 base differences (7.7%), and 116 base differences (8.2%) between the bacterium and Microvirgula aerodenitrificans, Vogesella indigofera, and Chromobacterium species, respectively. The G+C content (mean and standard deviation) is 68.0% +/- 2.43%, and the genomic size is about 3 Mb. Based on phylogenetic affiliation, the bacterium belongs to the Neisseriaceae family of the beta-subclass of Proteobacteria. For these reasons, a new genus and species, Laribacter hongkongensis gen. nov., sp. nov., is proposed, for which HKU1 is the type strain. Further studies should be performed to ascertain the potential of this bacterium to become an emerging pathogen.

Significance of local electrostatic interactions in staphylococcal nuclease studied by site-directed mutagenesis.

In this paper, we show that amino acids Glu(73) and Asp(77) of staphylococcal nuclease cooperate unequally with Glu(75) to stabilize its structure located between the C-terminal helix and beta-barrel of the protein. Amino acid substitutions E73G and D77G cause losses of the catalytic efficiency of 24 and 16% and cause thermal stability losses of 22 and 26%, respectively, in comparison with the wild type (WT) protein. However, these changes do not significantly change global and local secondary structures, based on measurements of fluorescence and CD(222 nm). Furthermore, x-ray diffraction analysis of the E75G protein shows that the overall structure of mutant and WT proteins is similar. However, this mutation does cause a loss of essential hydrogen bonding and charge interactions between Glu(75) and Lys(9), Tyr(93), and His(121). In experiments using double point mutations, E73G/D77G, E73G/E75G, and E75G/D77G, significant changes are seen in all mutants in comparison with WT protein as measured by fluorescence and CD spectroscopy. The losses of thermal stability are 47, 59, and 58%, for E73G/D77G, E73G/E75G, and E75G/D77G, respectively. The triple mutant, E73G/E75G/D77G, results in fluorescence intensity and CD(222 nm) close to those of the denatured state and in a thermal stability loss of 65% relative to the WT protein. Based on these results, we propose a model in which significant electrostatic interactions result in the formation of a locally stable structure in staphylococcal nuclease.

Crumpled structure of the custom hydrophobic lytic peptide cecropin B3.

The solution structure of a custom lytic peptide, cecropin B3 (CB3), having two identical hydrophobic segments on both the N- and C-termini, was investigated by two-dimensional NMR spectroscopy. The need to determine the structure of this peptide is rooted in its specific ability to lyse lipid layers that have a high content of anionic lipid. The lytic activities of CB3 on cell membranes including cancer cells and bacteria is found to be less than cecropin B1. The results show that CB3 has four discrete segments forming alpha helical structures. The crumpled structure of CB3 provides evidence for the lysis of the lipid layer being via a pathway that differs from pore formation. The results in this study provide strong clues towards a rational design for a potent antimicrobial and antitumor peptide.

Identification of slide coagulase positive, tube coagulase negative Staphylococcus aureus by 16S ribosomal RNA gene sequencing.

AIMS: To ascertain the clinical importance of a strain of slide coagulase positive but tube coagulase negative Staphylococcus species isolated from the blood culture of a 43 year old patient with refractory anaemia with excessive blasts in transformation who had neutropenic fever. METHODS: The isolate was investigated phenotypically by standard biochemical methods using conventional biochemical tests and two commercially available systems, the Vitek (GPI) and API (Staph) systems. Genotypically, the 16S ribosomal RNA (rRNA) gene of the bacteria was amplified by the polymerase chain reaction (PCR) and sequenced. The sequence of the PCR product was compared with known 16S rRNA gene sequences in the GenBank by multiple sequence alignment. RESULTS: Conventional biochemical tests did not reveal a pattern resembling a known Staphylococcus species. The Vitek system (GPI) showed that it was 94% S. simulans and 3% S. haemolyticus, whereas the API system (Staph) showed that it was 86.8% S. aureus and 5.1% S. warneri. 16S rRNA gene sequencing showed that there was a 0 base difference between the isolate and S. aureus, 28 base difference between the isolate and S. lugdunensis, 39 base difference between the isolate and S. schleiferi, 21 base difference between the isolate and S. haemolyticus, 41 base difference between the isolate and S. simulans, and 23 base difference between the isolate and S. warneri, indicating that the isolate was a strain of S. aureus. Vancomycin was subsequently prescribed and blood cultures taken four days after the start of treatment were negative. CONCLUSIONS: 16S rRNA gene sequencing was useful in ascertaining the clinical importance of the strain of slide coagulase positive but tube coagulase negative Staphylococcus species isolated from blood culture and allowing appropriate management.