High Prevalence of Carbapenem-Resistant Enterobacterales Producing OXA-48 among Carbapenem-Resistant Isolates in a Regional Hospital in Central Taiwan

In response to the increasing number of carbapenem-resistant Enterobacterales (CRE), we investigated carbapenemase-producing Klebsiella pneumoniae and non-K. pneumoniae epidemiology and genetics. We collected 76 clinical Enterobacterales and 4 stool surveillance Escherichia coli isolates resistant to ertapenem or imipenem. Using polymerase chain reaction (PCR) and DNA sequencing, we assessed carbapenemases, extended-spectrum β-lactamases, and AmpC β-lactamases. Molecular typing via pulsed-field gel electrophoresis (PFGE) and conjugation experiments were conducted to examine resistance gene transfer. Among the 80 isolates, 96.2% harbored at least one carbapenemase gene, with blaOXA-48 in 87.5%. KPC-2 and IMP-8 carbapenemases were found in 15.0 and 22.5% of the isolates, respectively, with 27.5% having 2 or more carbapenemase genes. The PFGE analysis revealed the presence of diverse genotypes. PCR-based plasmid replicon typing identified IncA/C as the most prevalent type among K. pneumoniae isolates (26/29), and IncF and IncFIB among E. coli isolates (22/28). Conjugal transfer was successful for plasmids encoding OXA-48, CTX-M-3, CTX-M-14, CMY-2, and other β-lactamases, except the KPC-2 gene. In conclusion, our study highlights high carbapenemase prevalence in CRE, primarily OXA-48. Multiple carbapenemases within strains were common, and PFGE showed diverse patterns in these carbapenem-resistant isolates.

[Molecular diagnostic strategies and management of dust mite allergy]

Dust mites are one of the most important allergens, widely distributed around the world, especially in household environments. Dermatophagoides pteronyssinus, Dermatophagoides farinae and Blomia tropicalis are the most common species of dust mites. There are more than 35 known sensitization components of dust mites, among which Der p 1, Der p 2 and Der p 23 are the major components. Clinically, allergen skin test and serum specific immunoglobulin E (sIgE) detection are widely used in the preliminary diagnosis of dust mite allergy. However, these methods cannot accurately identify specific dust mite sensitization components. Considering that there are significant differences in the allergenic components of dust mites in different regions and populations, component-resolved diagnosis of dust mite is particularly important in accurately determining the allergenic components. This is not only of guiding significance for allergen avoidance, but also important for determining the immunotherapy regimen for dust mites. In order to strengthen the understanding of the molecular diagnosis of dust mites and promote the integration of allergy science in China with the international standards, this article interprets the "Allergy Molecular Allergology User's Guide 2.0" published recently by the European Academy of Allergy and Clinical Immunology.

Investigation of carbapenem-resistant Klebsiella pneumoniae in Taiwan revealed strains co-harbouring blaNDM and blaOXA-48-like and a novel plasmid co-carrying blaNDM-1 and blaOXA-181

The emergence of carbapenem-resistant Klebsiella pneumoniae (CRKP) is related to the transmission of carbapenemase genes. Strains carrying more than one carbapenemase with a broadened spectrum of antibiotic resistance have been detected, which is concerning. Although blaKPC-encoding ST11-KL47/KL64 strains are dominant, other clones are emerging. This study investigated 137 CRKP from patients' blood samples in Taiwan. Polymerase chain reaction (PCR) was used to identify carbapenemase genes and capsular (KL) types. Most strains (56%, 77/137) possessed blaKPC alone; however, 12% (17/137) carried blaNDM+blaOXA-48-like and these strains showed high resistance to imipenem and meropenem. Strains carrying blaNDM+blaOXA-48-like predominantly belonged to KL51 (n=15), followed by KL64 (n=1) and KL47 (n=1). Whole-genome sequencing of one KL51 strain indicated that blaNDM-4 and blaOXA-181 are carried on two different plasmids. PCR was performed using specific primers located in these plasmids, and all blaNDM+blaOXA-48-like-encoding strains except the KL64 strain were considered to carry the two abovementioned plasmids. Genome analysis for the KL64 strain revealed that blaNDM-1 and blaOXA-181 are encoded in one plasmid. Notably, the KL51 blaOXA-181 plasmid shared high sequence similarity with the KL64 blaNDM-1+blaOXA-181 plasmid, except the KL64 plasmid comprised a 15,040-bp insertion encoding blaNDM-1. The data revealed KL51 as a predominant KL type carrying blaNDM-4+blaOXA-181, and identified a novel plasmid carrying blaNDM-1+blaOXA-181, highlighting the spread of specific plasmids and clones of CRKP in Taiwan.

Effects of dietary niacinamide and CP concentrations on the nitrogen excretion, growth performance, and meat quality of pigs

Reducing the dietary CP concentration in the formulation of low-protein diets without adverse effects on animal growth performance and meat quality remains challenging. In this study, we investigated the effects of nicotinamide (NAM) on the nitrogen excretion, growth performance, and meat quality of growing-finishing pigs fed low-protein diets. To measure the nitrogen balance, we conducted two trials: in nitrogen balance trial 1, four crossbred (Duroc × Landrace × Large White) barrows (40 ± 0.5 kg BW) were used in a 4 × 4 Latin square design with four diets and periods. The diets consisted of a basal diet + 30 mg/kg NAM (a control dose), basal diet + 90 mg/kg NAM, basal diet + 210 mg/kg NAM, and basal diet + 360 mg/kg NAM. In nitrogen balance trial 2, another four barrows (40 ± 0.5 kg BW) were used in a 4 × 4 Latin square design. The diets consisted of a basal diet + including 30 mg/kg NAM (control), basal diet + 360 mg/kg NAM, low-protein diet + 30 mg/kg NAM, and low-protein diet + 360 mg/kg NAM. To measure growth performance, two trials were conducted. In growth performance trial 1, 40 barrows (37.0 ± 1.0 kg) were randomly allocated to one of four dietary treatments (n = 10 per group), whereas in growth performance trial 2, 300 barrows (41.4 ± 2.0 kg) were randomly allocated to one of four dietary treatments, with each dietary treatment conducted in five repetitions with 15 pigs each. The four diets in the two growth performance trials were similar to those in nitrogen balance trial 2. Supplementing the diet with 210 or 360 mg/kg NAM reduced urinary nitrogen excretion and total nitrogen excretion and increased nitrogen retention comparted with the control diet (P < 0.05). Compared with the control diet, the low-protein diet with 360 mg/kg NAM reduced faecal, urinary, and total nitrogen excretion (P < 0.05) without affecting nitrogen retention and average daily gain (P > 0.05). Pigs fed the low-protein diet with 360 mg/kg NAM showed a decreased intramuscular fat content in the longissimus thoracis muscle when compared with pigs fed the control diet (P > 0.05). Our results suggest NAM as a suitable dietary additive to reduce dietary CP concentration, maximise nitrogen retention and growth performance, and decrease fat deposition in pigs.

Identification of three capsule depolymerases in a bacteriophage infecting Klebsiella pneumoniae capsular types K7, K20, and K27 and therapeutic application

BACKGROUND

Klebsiella pneumoniae capsular types K1, K2, K5, K20, K54, and K57 are prevalent hypervirulent types associated with community infections, and worrisomely, hypervirulent strains that acquired drug resistance have been found. In the search for alternative therapeutics, studies have been conducted on phages that infect K. pneumoniae K1, K2, K5, and K57-type strains and their phage-encoded depolymerases. However, phages targeting K. pneumoniae K20-type strains and capsule depolymerases capable of digesting K20-type capsules have rarely been reported. In this study, we characterized a phage that can infect K. pneumoniae K20-type strains, phage vB_KpnM-20.

METHODS

A phage was isolated from sewage water in Taipei, Taiwan, its genome was analyzed, and its predicted capsule depolymerases were expressed and purified. The host specificity and capsule-digesting activity of the capsule depolymerases were determined. The therapeutic effect of the depolymerase targeting K. pneumoniae K20-type strains was analyzed in a mouse infection model.

RESULTS

The isolated Klebsiella phage, vB_KpnM-20, infects K. pneumoniae K7, K20, and K27-type strains. Three capsule depolymerases, K7dep, K20dep, and K27dep, encoded by the phage were specific to K7, K20, and K27-type capsules, respectively. K20dep also recognized Escherichia coli K30-type capsule, which is highly similar to K. pneumoniae K20-type. The survival of K. pneumoniae K20-type-infected mice was increased following administration of K20dep.

CONCLUSIONS

The potential of capsule depolymerase K20dep for the treatment of K. pneumoniae infections was revealed using an in vivo infection model. In addition, K7dep, K20dep, and K27dep capsule depolymerases could be used for K. pneumoniae capsular typing.

[Analysis of specific sIgE detection of house dust mites and aspergillus fumigatus in 2 535 patients with respiratory allergic diseases and respiratory infectious diseases in the Guangzhou area]

Objective: To compare the specific IgE positive rates of the patients between allergic respiratory diseases and respiratory infectious diseases in Guangzhou, the relationship between the co-sensitization of house dust mite (HDM) allergen and Aspergillus fumigatus (AF) allergen and asthma, allergic rhinitis with asthma, pneumonia, upper respiratory infections, bronchitis, serum total immunoglobulin E (total Immunoglobulin E, tIgE) and age were analyzed, to provide the basis for the prevention and treatment of respiratory allergic diseases and respiratory infectious diseases in this area. Methods: A total of 2 535 patients with confirmed respiratory allergic diseases and respiratory infectious diseases were selected retrospectively from the outpatient or inpatient department of the First Affiliated Hospital of Guangzhou Medical University from April 2017 to June 2021 and detected HDM and AF specific IgE (sIgE) by the ImmunoCAP system. The age range was 1 to 89 years. The median age was 5 years. The average age was 9. ≤3 years old group n=894, 4-6 years old group n=721, 7-18 years old group n=615, 19-49 years old group n=207, >49 years old group n=98. There were 1 596 males (62.96%) and 939 females (37.04%). There were 1 279 cases of allergic diseases and 1 256 cases of respiratory infectious diseases. The different disease groups were divided into asthma group (411 cases), allergic rhinitis group (458 cases), allergic rhinitis combined with asthma group (410 cases), pneumonia group (463 cases), upper respiratory tract infection group (299 cases) and bronchitis group (494 cases). The difference of specific IgE (sIgE) and tIgE between HDM and AF was analyzed. For statistical analysis, continuous variables were tested by Mann-Whitney U. Classification data by chi-square test or Fisher's exact test. Results: 1 313 (51.79%) patients were sIgE positive for HDM allergen, 65 (2.56%) were sIgE positive for AF allergen, and 50 (1.97%) were both positive. In the respiratory allergic disease group, 877 cases (68.57%,877/1 279) were positive for HDM allergen sIgE, 57 cases (4.46%,57/1 279) were positive for AF allergen sIgE, and 44 cases (3.44%,44/1 279) were both positive; 436 cases (34.71%,436/1 256) of respiratory infectious diseases were positive for HDM allergen sIgE, 8 cases (0.64%,8/1 256) were positive for AF allergen sIgE, and 6 cases (0.48%,6/1 256) were both positive. In monosensitization, the HDM allergen sIgE sensitization rate was the highest in the allergic rhinitis & asthma group, at 80.24% (329/410). The positive rate of HDM allergen sIgE in male patients was 53.76%(858/1 596), and the positive rate in female patients was 46.22%(434/939), and the difference between the two was statistically significant (χ²=13.449, P<0.001). In polysensitization, asthma patients (5.35%,22/411) had the highest positive rate of HDM sensitization with AF, followed by allergic rhinitis patients (3.06%,14/458), allergic rhinitis with asthma (1.95%,8/410). The positive rate of respiratory infectious diseases such as pneumonia (0.43%,2/463), upper respiratory infections (0.33%,1/299), and bronchitis (0.61%,3/494) with AF was extremely low. The positive rate of HDM combined with AF in infants(≤3 years old group,0.34%, 3/894; 4-6 years old group, 0.97%, 7/721)was significantly lower than that in teenagers and adults(7-18 years old group,3.58%, 22/615; 19-49 years old group,6.28%, 13/207;>49 years old group,5.10%, 5/98).In the patients with HDM and AF combined sensitization, HDM sIgE levels were distributed in all grades, and AF sIgE levels were mainly in grades 1, 2, and 3. Conclusion: The positive rate of HDM combined with AF was higher in patients with respiratory allergic diseases such as asthma, allergic rhinitis, and allergic rhinitis combined with asthma, suggesting that clinical attention should be paid to the combination of HDM and AF in patients with asthma and allergic rhinitis, especially adults, more likely to be combined with AF.

Antimicrobial resistance genes and genetic characteristics of multidrug-resistant Escherichia coli in a veterinary hospital in Taiwan

Introduction. Antimicrobial resistance associated with animal hosts is easily transmitted to humans either by direct contact with resistant organisms or by transferring resistance genes into human pathogens.Gap statement. There are limited studies on antimicrobial resistance genes and genetic elements of multidrug-resistant (MDR) Escherichia coli in veterinary hospitals in Taiwan.Aim. The aim of this study was to investigate antimicrobial resistance genes in multidrug-resistant Escherichia coli from animals.Methodology. Between January 2014 and August 2015, 95 multidrug-resistant Escherichia coli isolates were obtained from pigs (n=66), avians (n=18), and other animals (n=11) in a veterinary hospital in Taiwan. Susceptibility testing to 24 antimicrobial agents of 14 antimicrobial classes was performed. Antimicrobial resistance genes, integrons, and insertion sequences were analysed by polymerase chain reaction and nucleotide sequencing. Pulsed-field gel electrophoresis (PFGE), and multi-locus sequence typing were used to explore the clonal relatedness of the study isolates.Results. Different antimicrobial resistance genes found in these isolates were associated with resistance to β-lactams, tetracycline, phenicols, sulfonamides, and aminoglycosides. Fifty-five of 95 E. coli isolates (55/95, 57.9 %) were not susceptible to extended-spectrum cephalosporins, and bla _CTX-M-55 (11/55, 20.0 %) and bla _CMY-2 (40/55, 72.7 %) were the most common extended-spectrum β-lactamase (ESBL) and AmpC genes, respectively. Both bla _CTX-M and bla _CMY-2 were present on conjugative plasmids that contained the insertion sequence ISEcp1 upstream of the bla genes. Plasmid-mediated FOX-3 β-lactamase-producing E. coli was first identified in Taiwan. Forty isolates (40/95, 42 %) with class 1 integrons showed seven resistance phenotypes. Genotyping of 95 E. coli isolates revealed 91 different XbaI pulsotypes and 52 different sequence types. PFGE analysis revealed no clonal outbreaks in our study isolates.Conclusion. This study showed a high diversity of antimicrobial resistance genes and genotypes among MDR E. coli isolated from diseased livestock in Taiwan. To our knowledge, this is the first report of plasmid-mediated ESBL in FOX-3 β-lactamase-producing E. coli isolates in Taiwan. MDR E. coli isolates from animal origins may contaminate the environment, resulting in public health concerns, indicating that MDR isolates from animals need to be continuously investigated.

Emergence and nosocomial spread of ST11 carbapenem-resistant Klebsiella pneumoniae co-producing OXA-48 and KPC-2 in a regional hospital in Taiwan

Purpose. Carbapenem-resistant Klebsiella pneumoniae (CRKP) has emerged as a major challenge for global healthcare systems. The objectives of this study were to determine the nosocomial spread of CRKP clones and analyse the molecular characteristics of CRKP in our hospital.Methodology. Ninety-eight non-duplicated clinical CRKP isolates were collected from March 2014-June 2015. Clinical, demographic and microbiological data of patients with CRKP were reviewed. Pulsed-field gel electrophoresis (PFGE) and multi-locus sequence typing were applied to investigate the genetic relationship between the 98 isolates. Antibiotic resistance genes were identified by conventional PCR-sequencing.Results. PFGE patterns were grouped into 26 clusters. Two main PFGE clusters were identified: L (53 isolates, belonging to ST11) and N (11 isolates, belonging to ST11). The most dominant ST was ST11 (79 %, 77/98), followed by ST273 (5 %, 5/98). KPC-2 (n=82) was the predominant carbapenemase followed by OXA-48 (n=64). Fifty isolates (51 %, 50/98) harboured bla _KPC-2 and bla _OXA-48 simultaneously, and three of these isolates were detected with the third carbapenemase genes (bla _IMP-8 or bla _VIM-1).Conclusion. The clonal spread of K. pneumoniae ST11 expressing OXA-48, KPC-2 and CTX-M-14 β-lactamases was the cause of an outbreak of CRKP. To the best of our knowledge, a single strain harbouring A-, B- and D-class carbapenemase genes has not previously been identified. There is a high prevalence of plasmid-encoded KPC-2- and OXA-48-producing CRKP in our hospital; most isolates were members of ST11, which may be representative of a high-risk CRKP clone disseminating in central Taiwan.

Identification of CFE-2, a new plasmid-encoded AmpC β-lactamase from a clinical isolate of Citrobacter freundii

A clinical isolate of Citrobacter freundii (JA99) obtained from a bile culture of a Taiwanese patient was found to produce a plasmid-encoded β-lactamase conferring resistance to oxyimino-cephalosporins and cephamycins. Resistance arising from production of the β-lactamase could be transferred by conjugation with an IncW plasmid (pJA99) into Escherichia coli J53. The substrate and inhibition profiles of this enzyme resembled that of an AmpC β-lactamase. The resistance gene of pJA99, cloned and expressed in E. coli DH5α, was shown to contain an open reading frame showing 92% amino acid identity with the plasmid-encoded enzyme CFE-1 of E. coli KU6400. DNA sequence analysis also identified a gene upstream of ampC in pJA99 whose sequence was 95.0% identical to the ampR gene from E. coli KU6400. In addition, orf1, the fumarate operon (frdABCD), blc, lolB and repB surrounding the ampR-ampC genes in C. freundii were identified. This DNA fragment was absent in other Citrobacter spp. Therefore, we describe a new plasmid-encoded AmpC β-lactamase, named CFE-2. This study highlights the emergence of broad-spectrum cephalosporin resistance in C. freundii owing to a new type of AmpC β-lactamase.

Genetic characteristic of class 1 integrons in proteus mirabilis isolates from urine samples

Background: Proteus mirabilis is an opportunistic pathogen, commonly associated with complicated urinary tract infections (UTIs). UTIs caused by multidrug-resistant Proteus mirabilis have increased worldwide. Multidrug-resistance of Gram-negative enteric bacteria is usually associated with class 1 integrons.

Purposes: To investigate the prevalence and characterize gene cassettes of class 1 integrons in multidrug-resistant P. mirabilis

Methods: From 2006 to 2008, 314 P. mirabilis isolates from urine were collected from a regional teaching hospital. Antimicrobial resistance of the isolates was determined by disk diffusion methods. The phenotypic confirmatory test of extended-spectrum β-lactamase (ESBL) production was performed as described in the Clinical and Laboratory Standards Institute (CLSI) guideline. The genetic organization of the class 1 integron cassettes was investigated by PCR, cloning, and sequencing of the regions surrounding these genes.

Results: Seventy-nine (25%, 79/314) P. mirabilis isolates were ESBL-producing and most ESBL-producing P. mirabilis were positive for bla_CTX-M. Class 1 integrons were presented in 76 isolates (24.2%, 76/314), and were more frequently found in ESBL-positive (55/79, 70%) than ESBL-negative (21/235, 8.9%) P. mirabilis isolates. The most prevalence of the cassettes encoded resistance genes were aminoglycoside (aac(6’)-Ib, aacA7, aadAl, aadA2, and aadAla), trimethoprim (dfrAl and dfrA12) and chloramphenicol (catB3 and cmlA6). The most prevalent cassette of dfr12-orfF-aadA2 was found in 49 isolates. The cassette array aadB-catB3-oxa10-aadA1 was first found in P. mirabilis. The enterobacterial repetitive intergenic consensus (ERIC)-PCR fingerprinting patterns were detected in these 76 integron positive P. mirabilis isolates and belonged to 8 profiles.

Conclusion: This study investigated the prevalence and characterized gene cassettes of class 1 integrons in MDR P. mirabilis isolates from urine samples. The frequency of gene cassettes in P. mirabilis were partially by clonal spread of the carriers and the results could provide information for effective antimicrobial therapy and infection control.

Identifying substance misuse in primary care: TAPS Tool compared to the WHO ASSIST

BACKGROUND

There is a need for screening and brief assessment instruments to identify primary care patients with substance use problems. This study's aim was to examine the performance of a two-step screening and brief assessment instrument, the TAPS Tool, compared to the WHO ASSIST.

METHODS

Two thousand adult primary care patients recruited from five primary care clinics in four Eastern US states completed the TAPS Tool followed by the ASSIST. The ability of the TAPS Tool to identify moderate- and high-risk use scores on the ASSIST was examined using sensitivity and specificity analyses.

RESULTS

The interviewer and self-administered computer tablet versions of the TAPS Tool generated similar results. The interviewer-administered version (at cut-off of 2), had acceptable sensitivity and specificity for high-risk tobacco (0.90 and 0.77) and alcohol (0.87 and 0.80) use. For illicit drugs, sensitivities were >0.82 and specificities >0.92. The TAPS (at a cut-off of 1) had good sensitivity and specificity for moderate-risk tobacco use (0.83 and 0.97) and alcohol (0.83 and 0.74). Among illicit drugs, sensitivity was acceptable for moderate-risk of marijuana (0.71), while it was low for all other illicit drugs and non-medical use of prescription medications. Specificities were 0.97 or higher for all illicit drugs and prescription medications.

CONCLUSIONS

The TAPS Tool identified adult primary care patients with high-risk ASSIST scores for all substances as well moderate-risk users of tobacco, alcohol, and marijuana, although it did not perform well in identifying patients with moderate-risk use of other drugs or non-medical use of prescription medications. The advantages of the TAPS Tool over the ASSIST are its more limited number of items and focus solely on substance use in the past 3months.

Why not nursing? A systematic review of factors influencing career choice among healthcare students

BACKGROUND

A global shortage of healthcare professionals calls for effective recruitment and retention strategies. The nursing profession faces greater staffing shortages compared with other healthcare professions. Identifying these factors for choosing a career in health care is an important step in structuring future nursing recruitment strategies.

AIM

This systematic review examined the motivations for choosing a career in health care, then compared them to factors that influence the choice to pursue a career in nursing.

METHODS

A literature search of the CINAHL, PubMed, Web of Science and Scopus databases for articles published between 2002 and 2013 was conducted. The search included studies that focused on factors influencing career choice among undergraduate medicine, dentistry, pharmacy and nursing students.

RESULTS

A total of 29 papers were included in the review. The themes and subthemes that emerged from this review included: (1) intrinsic factors, including a desire to help others and a personal interest in health care, (2) extrinsic factors, such as financial remuneration, job security, professional prestige and job autonomy, (3) socio-demographic factors such as gender and socio-economic status, and (4) interpersonal factors, encompassing the influence of family and other professional individuals.

DISCUSSION

Healthcare professionals were generally motivated by intrinsic factors. However, public perceptions of nursing as a low-paying and low-status job have significantly hindered the participants' choice to pursue it as a career.

CONCLUSION AND IMPLICATIONS FOR NURSING AND/OR HEALTH POLICY

Nursing institutions could provide more platforms to help school leavers better understand the nursing career. In turn, hospital administrators could invite parents to nursing career fairs, increase financial remuneration for nurses, and provide decision-making avenues aimed at recruiting and retaining more nurses.

Characterization of IS26-composite transposons and multidrug resistance in conjugative plasmids from Enterobacter cloacae

SHV-12 is the most widespread resistance determinant of Enterobacter cloacae in Taiwan; however, blaSHV-12 has rarely been mobilized. Six multidrug-resistant E. cloacae isolates were collected. After conjugal transfer, plasmid profiling and analysis of incompatibility groups was performed to characterize the genetic context of blaSHV-12 -containing fragments. The presence of mobile genetic elements was demonstrated by PCR, cloning, sequencing and bioinformatics analyses. Four different β-lactamase genes (blaTEM-1 , blaSHV-12 , blaCTX-M-3 and/or blaCTX-M-14 ) were observed in the conjugative plasmids belonging to the IncHI2 (n = 4), IncI1 or IncP incompatibility groups. The IS26-blaSHV-12 -IS26 locus was located in five different genetic environments. A novel structural organization of a class 1 integron with the aac(6')-IIc cassette truncated by IS26 was identified in one isolate. Thus, blaSHV-12 was obtained from different plasmids through IS26-mediated homologous recombination. IS26 plays a vital role in the distribution of mobile resistance elements between different plasmids found in multidrug-resistant E. cloacae isolates.

Impact of cholesterol on disease progression

Cholesterol-rich microdomains (also called lipid rafts), where platforms for signaling are provided and thought to be associated with microbe-induced pathogenesis and lead to cancer progression. After treatment of cells with cholesterol disrupting or usurping agents, raft-associated proteins and lipids can be dissociated, and this renders the cell structure nonfunctional and therefore mitigates disease severity. This review focuses on the role of cholesterol in disease progression including cancer development and infectious diseases. Understanding the molecular mechanisms of cholesterol in these diseases may provide insight into the development of novel strategies for controlling these diseases in clinical scenarios.

Medical students' awareness and perception of national health examinations

Key ingredients for upgrading health care include bolstering and appraising professional medical education. Health examination as a crucial element of health care that we must incorporate into medical education. This research evaluates medical students' awareness of national health examinations. Two surveys, focused on health examination knowledge and perspective, were conducted for first- to fourthyear medical students, results analyzed by descriptive statistics, t-test and ANOVA. Research subjects scored maximum 11 (of possible 15): i.e., 76.2% accuracy for health examination knowledge questions and held positive views on seven (58%) perspective-related questions. Self-directed learning courses do provide a positive effect on students' learning. Respondents' varying backgrounds had insignificant impact on overall results, but in-depth analysis for each individual question does reveal differences among several backgrounds. Medical students' overall awareness level for health examination is above average in comparison to the general public. This research result can provide a basis to improve the related professional programs, courses and teachings or used as a reference for modifications on future classes. The above observations were discussed based on the medical education system in Taiwan.

Dental and medical students' perspectives on early exposure to PBL in Taiwan

A hybrid problem-based learning (PBL) curriculum adopted in 2002 for medical students at China Medical University, Taiwan, was extended to dental students in 2007. Before that, PBL workshops were conducted for all students. Two PBL cases on basic biomedical issues were used for second-year medical students and second-year dental students to explore the feasibility of adopting PBL as part of the dental curriculum. This study compared the medical and dental students' attitudes toward the PBL tutorials and PBL curricula. Upon completion of the PBL component, an eighteen-item questionnaire asked students to assess (on a ten-point scale with 10 as the most positive response) their perceptions of the learning process in the PBL tutorials. Forty-six dental students from a cohort of fifty (92 percent) and 107 medical students from a cohort of 119 (90 percent) completed the questionnaires (fifty-three females and 100 males). The importance of all items was rated above 6.00. The medical students' mean score (7.29) was higher than the dental students' mean score (7.10). Of the eighteen attributes of the PBL process, the students indicated being generally comfortable with fourteen. No statistical significance was found between the dental and medical students' scores, but there was a significant difference (p=0.006) in their perception of PBL curricula. Overall, the medical students expressed a more positive outlook toward the PBL learning process than the dental students and were more willing to accept PBL as a pedagogy.

Fusidic acid resistance among clinical isolates of methicillin-resistant Staphylococcus aureus in a Taiwanese hospital

Background

The prevalence of resistance to fusidic acid of methicillin-resistant Staphylococcus aureus (MRSA) was increased each year in a Taiwan hospital. Thirty-four MRSA clinical isolates collected in 2007 and 2008 with reduced susceptibility to FA were selected for further evaluation the presence of resistance determinants.

Results

The most common resistance determinant was fusC, found in 25 of the 34 MRSA isolates. One of the 25 fusidic acid-resistant MRSA harboured both fusB and fusC, which is the first time this has been identified. Mutations in fusA were found in 10 strains, a total of 3 amino-acid substitutions in EF-G (fusA gene) were detected. Two substitutions with G₅₅₆S and R₆₅₉L were identified for the first time. Low-level resistance to fusidic acid (MICs, ≤ 32 μg/ml) was found in most our collection. All collected isolates carried type III SCCmec elements. MLST showed the isolates were MRSA ST239. PFGE revealed nine different pulsotypes in one cluster.

Conclusions

Our results indicate that the increase in the number of fusidic acid resistant among the MRSA isolates in this hospital is due mainly to the distribution of fusC determinants. Moreover, more than one fusidic acid-resistance mechanism was first detected in a same stain in our collection.

Investigation of carbapenem-resistant Acinetobacter baumannii isolates in a district hospital in Taiwan

A total of 34 Acinetobacter baumannii isolates from a district hospital in Taiwan were identified with carbapenem-hydrolyzing oxacillinase OXA-66/OXA-51-like. In addition, 26 of 28 carbapenem-resistant isolates harbored plasmid-encoded bla(OXA-23)-like genes. Twenty of 28 carbapenem-resistant isolates mapped to the major genotype cluster A of carbapenemase producer by pulsed-field gel electrophoresis.

Characterization of extended-host-range pseudo-T-even bacteriophage Kpp95 isolated on Klebsiella pneumoniae

Kpp95, isolated on Klebsiella pneumoniae, is a bacteriophage with the morphology of T4-type phages and is capable of rapid lysis of host cells. Its double-stranded genomic DNA (ca. 175 kb, estimated by pulsed-field gel electrophoresis) can be cut only by restriction endonucleases with a cleavage site flanked either by A and T or by T, as tested, suggesting that it contains the modified derivative(s) of G and/or C. Over 26 protein bands were visualized upon sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the virion proteins. N-terminal sequencing indicated that the most abundant band (46 kDa) is the major coat protein (gp23) which has been cleaved from a signal peptide likely with a length similar to that of T4. Phylogenetic analyses based on the sequences of the central region (263 amino acid residues) of gp23 and the full length of gp18 and gp19 placed Kpp95 among the pseudo-T-even subgroup, most closely related to the coliphage JS98. In addition to being able to lyse many extended-spectrum beta-lactamase strains of K. pneumoniae, Kpp95 can lyse Klebsiella oxytoca, Enterobacter agglomerans, and Serratia marcescens cells. Thus, Kpp95 deserves further studies for development as a component of a therapeutic cocktail, owing to its high efficiencies of host lysis plus extended host range.

Genetic association of blaSHV-5 with transposable elements IS26 and IS5 in Klebsiella pneumoniae from Taiwan

A cloned 5,248-bp EcoRI fragment from the Klebsiella pneumoniae transferable plasmid pKP53 (> 70 kb) containing bla(SHV-5) was sequenced. Insertion sequences IS26 and IS5 were found downstream from bla(SHV-5). The DNA sequences of the genetic environment surrounding bla(SHV-5) were homologous to plasmid p1658/97 from Escherichia coli, containing a truncated recF gene and a truncated deoR gene upstream and downstream from bla(SHV-5), respectively. RecF may be involved in bla(SHV-5) translocation to the plasmid by RecF-dependent recombination. This novel genetic environment may be associated with the successful proliferation and/or expression of SHV-5 in K. pneumoniae strains from Taiwan.

Clinical experiences of the infections caused by extended-spectrum beta-lactamase-producing Serratia marcescens at a medical center in Taiwan

CTX-M-3 has become the most common extended-spectrum beta-lactamase (ESBL) produced by Serratia marcescens in Taiwan. An expanded effort to detect ESBL among 123 nonrepetitive isolates of S. marcescens was made and 15 (12%) ESBL-producers were identified, all revealing CTX-M-3. Without routinely detecting the ESBL for S. marcescens in clinical laboratories, 80% of the ESBL-producers were reported to be susceptible to cefepime. The clinical spectrum of ESBL-producing S. marcescens-related infections included febrile urinary tract infection (n = 3); afebrile pyuria (n = 2); pneumonia (n = 3); spontaneous bacterial peritonitis (n = 3); secondary bacteremia (n = 2) and one each with primary bacteremia and colonization of the central catheter tip. Overall, the 30-day mortality rate was 33.3% (5/15) and the outcome depended on the severity of the underlying disorder and infection per se. In conclusion, although our case numbers were limited, due to the substantial incidence and associated mortality of ESBL-producing S. marcescens and its potential treatment failure by an apparently susceptible cephalosporin, we recommend that the detection and report of ESBL production for S. marcescens in clinical laboratories be made mandatory.

Involvement of Bax, Bcl-2, Ca2+ and caspase-3 in capsaicin-induced apoptosis of human leukemia HL-60 cells

The role of Ca2+ on the effects of capsaicin on human leukemia HL-60 cells in vitro and the molecular mechanisms of capsaicin-induced apoptosis were investigated. The flow cytometric analysis indicated that capsaicin decreased the percentage of viable HL-60 cells, via the induction of G0/G1-phase cell cycle arrest and apoptosis. Capsaicin-induced G0/G1-phase arrest involved the suppression of CDK2 and the cyclin E complex, which are check-point enzymes for cells moving from G0/G1- to S-phase. Capsaicin-induced apoptosis was associated with the elevation of intracellular reactive oxygen species and Ca2+ production, decreased the levels of mitochondrial membrane potential, promoted cytochrome c release and increased the activation of caspase-3. An intracellular Ca2+ chelator (BAPTA) significantly inhibited capsaicin-induced apoptosis. Capsaicin-induced apoptosis was time-and dose-dependent. These results suggest that the capsaicin-induced apoptosis of HL-60 cells may result from the activation of caspase-3 and the intracellular Ca2+ release pathway.

Curcumin inhibits cell migration of human colon cancer colo 205 cells through the inhibition of nuclear factor kappa B /p65 and down-regulates cyclooxygenase-2 and matrix metalloproteinase-2 expressions

Curcumin (diferuloylmethane) is a chemical derived from several Curcuma species (turmeric), possessing anti-inflammatory and antioxidant properties and which, thus, may be a potential anticancer drug. However, its mechanism of action is not fully understood. Our previous studies had shown that curcumin induced cytotoxicity, cell cycle arrest and apoptosis in human colon cancer colo 205 cells. In this study, curcumin affected the levels of NF-kappaB/ p65 in a time-dependent manner but did not affect NF-kappaB/ p50, based on Western blotting methods. In vitro experiments revealed that curcumin inhibited Cox-2 levels, but promoted those of Cox-1 in colo 205 cells. Curcumin also inhibited MMP-2 levels and promoted MMP-9 levels, but did not affect MMP-7 levels, based on Western blotting assays. These effects were also confirmed by cDNA microarray. Remarkably, curcumin not only exerted its effect on the protein levels of NF-kappaB, Cox-1 and -2, MMP-2 and -7, but also directly inhibited their mRNA levels. Curcumin was also found to significantly repress the in vitro invasion of colo 205 cells.

Dissemination of Proteus mirabilis isolates harboring CTX-M-14 and CTX-M-3 β-lactamases at 2 hospitals in Taiwan

From February to June 2003, 111 clinical isolates of Proteus mirabilis were mainly isolated from patients with respiratory or urinary tract infections hospitalized at 3 district hospitals (A, B, C) in central Taiwan. Among them, 34 (30.6%) strains, isolated within 2 hospitals (A and B), exhibited nonsusceptibility to cefotaxime with significant reduction of MIC (> or = 3 log2 dilution) by the effect of clavulanic acid, which confirmed the phenotype of extended-spectrum beta-lactamases (ESBLs). These ESBL producers were coresistant to gentamicin, isepamicin, and amikacin, but remained susceptible to ceftazidime (MIC, < or = 0.5 microg/mL) and meropenem (MIC, <0.5 microg/mL). By isoelectric focusing analysis, polymerase chain reaction, and nucleotide sequencing, we detected the presence of CTX-M-14 in 33 strains and CTX-M-3 in 6 strains (5 strains harboring both CTX-M-14 and CTX-M-3 enzymes). These beta-lactamase genes can be successfully transferred by the conjugative plasmid. Molecular epidemiology of the 34 ESBL-producing P. mirabilis strains by pulsed-field gel electrophoresis using SfiI restriction enzyme revealed 9 different genotypes, suggesting epidemic clones with intra- and interhospital spread. In conclusion, the broadly extended clonal spreading of CTX-M-type P. mirabilis was first discovered at the district hospitals in Taiwan.

Berberine inhibits arylamine N-acetyltransferase activity and gene expression in Salmonella typhi

The effects of berberine on growth, arylamine N-acetyltransferase (NAT) activity, and gene expression in Salmonella Typhi (Typhi) were described. The growth inhibition of Typhi was determined by measuring absorbance by optical density (OD at 650 nm). The NAT activity was determined by measuring the levels of 2-aminofluorene (AF) and N-acetyl-2-aminofluorene (AAF) by high-performance liquid chromatography. The results demonstrated that 24-h berberine treatment decreased bacteria growth and amounts of AAF in Typhi. Western blotting and flow cytometry were used for examining the levels of NAT after bacteria were cotreated with or without various concentrations of berberine, and results indicated that berberine decreased the levels of NAT in Typhi. Polymerase chain reaction was used for examining the gene expression of NAT (mRNA NAT), and results indicated that berberine affects mRNA NAT1 expression in Typhi.

(-)-Menthol inhibits DNA topoisomerases I, II alpha and beta and promotes NF-kappaB expression in human gastric cancer SNU-5 cells

It has been reported that (-)-Menthol can inhibit the growth of rat liver epithelial tumor cells and is a potent chemopreventive agent. The purpose of the present experiment was to examine and identify cellular processes leading to cell death which are affected by (-)-Menthol in human gastric SNU-5 cancer cells. Cell death (cytotoxicity) was examined and analyzed by trypan blue stain and flow cytometric methods. It was shown that (-)-Menthol inhibited the proliferation of the cells in a dose- and time-dependent manner, inhibited topoisomerase I, IIa and IIbeta, but promoted the levels of NF-kappaB gene expression based on the Western blot and polymerase chain reaction (PCR) and cDNA microarray methods. These data suggest that (-)-Menthol may induce cytotoxicity through inhibiting gene expression of topoisomerase I, IIalpha and IIbeta and promoting the gene expression of NF-kappaB in SNU-5 cells.

Detection of cefotaxime-resistant CTX-M-3 in clinical isolates of Serratia marcescens

Strains of Serratia marcescens (isolated in a hospital during April and August 2000) resistant to ampicillin, chloramphenicol, trimethoprim-sulfamethoxazole, streptomycin, tetracycline, and gentamicin were characterized. Out of a total of 34 clinical isolates 6 (17.6 %) exhibited the extended spectrum beta-lactamases (ESBL) resistance; they were also resistant to cefotaxime (minimum inhibitory concentration, MIC > or = 128 microg/mL) but susceptible to imipenem (MIC < or = 0.5 microg/mL). This multidrug resistance was shown to be transferred by a conjugative plasmid. Transconjugants revealed similar MIC profiles when compared to the parental strains. Isoelectric focusing revealed one major transferable beta-lactamase (pI 8.4) which was further identified as CTX-M-3 by PCR and gene sequencing. The presence of strains with this type of ESBL showed the evolution of bla genes and their dissemination among at least three species of the family Enterobacteriaceae isolated within a single hospital. The predominance of CTX-M type enzymes found in this area of Taiwan appeared to be similar to that described in Poland.

Effects of tannic acid and its related compounds on food mutagens or hydrogen peroxide-induced DNA strands breaks in human lymphocytes

The effect of tannic acid (TA), gallic acid (GA), propyl gallate (PA) and ellagic acid (EA) on DNA damage in human lymphocytes induced by food mutagens [3-amino-1-methyl-5H-pyrido (4,3-b) indole (Trp-P-2) and 2-amino-1-methyl-6-phenylimadazo (4,5-b) pyridine (PhIP) or H2O2 was evaluated by using single-cell electrophoresis (comet assay). The toxicity of these tested compounds (0.1-100 microg/ml) on lymphocytes was not found. These compounds did not cause DNA strand breaks at lower concentrations of 0.1-10 microg/ml. At a concentration of 100 microg/ml, TA and GA exhibited slight DNA damage, whereas PA and EA showed no DNA strand breaks. TA and its related compounds decreased the DNA strand breaks induced by Trp-P-2, PhIP or H2O2 at concentrations of 0.1-10 microg/ml. DNA repair enzymes endonuclease III (Endo III) and formamidopyrimidine-DNA glycoslase (FPG)] were used to examine the levels of oxidised pyrimidines and purines in human lymphocytes induced by H2O2. All the compounds at 10 microg/ml can reduce the level of FPG sensitive sites. However, only EA inhibited the formation of EndoIII sensitive sites. The results indicated that these compounds can enhance lymphocytes resistance towards DNA strand breaks induced by food mutagens or H2O2 in vitro.

Survey of CTX-M-3 extended-spectrum beta-lactamase (ESBL) among cefotaxime-resistant Serratia marcescens at a medical center in middle Taiwan

Thirty-four clinical isolates of Serratia marcescens nonsusceptible to cefotaxime were collected from a medical center in middle Taiwan. Confirmatory tests for extended-spectrum beta-lactamases (ESBLs) by cefotaxime and ceftazidime +/- clavulanic acid using Etest ESBL Screen identified only one ESBL producer; the remaining 33 isolates revealed nondeterminable results, because of off-scale minimum inhibitory concentration (MIC) levels for cefotaxime +/- clavulanic acid. Agar microdilution method using broader MIC ranges confirmed 21 ESBL-producers and one non-determinable result, achieving a highly predicting value compared to golden standard by PCR and DNA sequencing analysis, which identified 22 (65%) isolates containing blaCTX-M-3 genes. Only one strain carried concurrent CTX-M-3 and SHV-5 conferring high-level MICs to both cefotaxime (128 microg/mL) and ceftazidime (64 microg/mL). Other enzymatic mechanisms, such as chromosome-encoded AmpC including a novel SRT-2 enzyme, may confer resistance to cefotaxime on the remaining 12 isolates without ESBL bla genes. Thus, it is unreliable to predict the resistance mechanism by antibiogram, and current Etest ESBL Screen tests. Our study highlights expanding efforts to detect ESBLs in S. marcescens are urgently needed in Taiwan.

The inhibition of N-acetyltransferase activity and gene expression in human bladder cancer cells (T24) by shikonin

Shikonin has the potential to prevent, or be used in the treatment of, bladder transitional cell carcinoma induced by arylamines. We evaluated its effectiveness by measuring the amount of acetylated 2-aminofluorene (AF), AF-DNA adducts, changes of NAT mRNA and the amount of NAT enzyme. T24 human bladder cancer cells were incubated with 30 microM AF with different concentrations of shikonin for various times. T24 cells treated with shikonin (16 microM) were then harvested and used in 2 experiments: 1). T24 cells were incubated with 22.5 microM AF and shikonin (0, 16 microM) (co-treatment) for 6, 12, 18, 24 and 48 h. 2). T24 cells were incubated with various concentrations of AF and shikonin (0, 16 microM) for 24 h. AF and AAF were measured by HPLC. Then in the prepared human T24 cell cytosols different concentrations of AF and shikonin were added to measure the kinetic constants of NAT. Next, AF-DNA adducts in human T24 cells with or without treatment with shikonin were detected and measured. The final two steps included measuring the NAT Ag-Ab complex after treatment with and without shikonin and evaluating the effect of shikonin on the NAT genes. Higher concentrations of shikonin induced decreasing AF acetylation. We found that the longer the culture period, the greater the difference in AF acetylation in the same shikonin concentrations. It was also noted that increase in AAF was proportional to incubation time. In the presence of 16 microM of shikonin, N-acetylation of AF decreased by up to 72-84%. Shikonin decreased the amount of AAF production in human T24 cells in all examined AF doses. Both Km and Vmax values in the cytosolic NAT decreased after the addition of shikonin to the cytosol. Finally, shikonin decreased the amount of AAF production and AF-DNA adducts formation in human 724 cells in all examined AF doses. The percentage of cells stained by antibody was significantly different after treatment with shikonin, especially with the higher shikonin concentrations. The NAT1 mRNA level and the NAT1/beta-actin ratio decreased significantly with higher concentrations (16-24 microM) of shikonin. Shikonin affected NAT activity, gene expression (NAT1 mRNA), AF-DNA adducts formation and formation of NAT Ag-Ab in human bladder tumor T24 cells. Therefore, shikonin should be considered as a candidate agent for the prevention or treatment of transitional cell carcinoma.

Confirmation of extended-spectrum beta-lactamase-producing Serratia marcescens: preliminary report from Taiwan

Although Serratia marcescens is a common cause of nosocomial infection in Taiwan, strains producing extended-spectrum beta-lactamases (ESBLs) are rare. We detected four clinical isolates of S. marcescens from Taiwan that exhibited resistance to cefotaxime (MICs, > 256 microg/ml) and cefepime (MICs, > or = 32 microg/ml), but were susceptible to imipenem and meropenem. Transconjugants revealed similar MIC profiles when compared to the parental strains. Isoelectric focusing revealed one major transferable beta-lactamase (pI 8.4), which was further identified as CTX-M-3 by polymerase chain reaction and gene sequencing. An AmpC-like enzyme (pI 8.8) was not transferable. All four isolates had significant MIC reductions of > or =3 log(2) dilutions for cefepime in the presence of clavulanic acid, compatible with the presence of an ESBL (CTX-M-3). Clavulanate did not significantly reduce the cefotaxime MIC for one isolate that may co-produce high-level AmpC beta-lactamase (pI 8.8). Since high-level AmpC expression has minimal effect on the activity of cefepime, isolates co-producing AmpC beta-lactamase may be recognized as additional ESBL producers by using cefepime as an ESBL screening agent.

Effect of norcantharidin on N-acetyltransferase activity in HepG2 cells

The inhibition ofarylamine N-acetyltransferase (NAT) activity by norcantharidin (NCTD), the demethylated form of cantharidin, in human hepatocellular carcinoma HepG2 cells was investigated. By using high performance liquid chromatography, NAT activity on acetylation of 2-aminofluorene (AF) and p-aminobenzoic acid (PABA) were examined. Two assay systems were performed, one with cellular cytosols, the other with intact HepG2 cell suspensions. The NAT activity in HepG2 cell line was inhibited by norcantharidin in a dose-dependent manner in both types of examined systems: i.e. the greater the concentration of norcantharidin in the reaction, the greater the inhibition of NAT activities. This report is the first to show that norcantharidin has an inhibitory effect on NAT activity in HepG2 cell.

Engineering, expression, and renaturation of a collagen-targeted human bFGF fusion protein

Basic fibroblast growth factor (bFGF) is a potent in vitro mitogen for capillary endothelial cells, stimulates angiogenesis in vivo, and may participate in tissue repair. Basic FGF is found in abundance in tissues such as brain, kidney and cartilage. This study reports the expression, purification, and renaturation of a biologically active human basic fibroblast growth factor fusion protein (hbFGF-F1) from Escherichia coli. A prokaryotic expression vector was engineered to produce a tripartite fusion protein consisting of (i) a purification tag, (ii) a protease-sensitive linker/collagen-binding domain, and (iii) cDNA sequence encoding the active fragment of hbFGF. The expressed hbFGF-F1 and hbFGF-F2 (it contains a collagen-binding domain), located in inclusion bodies, were solubilized with 6 M guanidine-HCl and renatured using a glutathione redox system and protracted dialysis under various experimental conditions. The purification of the recombinant proteins was achieved by binding the His-tag of the fusion protein on a Ni-NTA metal chelate column. The biological activity of the recombinant growth factors was demonstrated by their ability to stimulate proliferation of human vein endothelial cells (HVEC), monitored by [3H]-thymidine incorporation, where commercial recombinant human bFGF (rhbFGF) served as a positive control. Purified rhbFGF-F1 and rhbFGF-F2 constructs exhibited proliferative activity comparable to commercial rhbFGF. Binding of the renatured hbFGF-F2 fusion protein to collagen was demonstrated by stable binding on a collagen-conjugated Sephadex-G15 column. The high affinity binding was also demonstrated by the binding of [3H]-collagen to the rhbFGF-F2 protein immobilized on a Ni-NTA column. The rhbFGF-F2 fusion protein bound to collagen coated surfaces with high affinity but exhibited comparatively lower biological activity than the fusion protein in solution, suggesting a potentially latent configuration. Taken together, these results demonstrate that biologically active rhbFGF fusion proteins can be recovered from transformed bacteria by oxidative refolding; thus, providing a means for its high-yield production, purification, and renaturation from microorganisms. Furthermore, we demonstrate that the auxiliary collagen-binding domain effectively targets the recombinant growth factor to type I collagen. The clinical effect of rhbFGF-F2 on wound healing is also studied in streptozotocin-induced diabetic rats and evaluated by histological examination comparing with rhbFGF-F1 and commercial bFGF effects. The highly beneficial effects of rhbFGF-F2 on wound healing is suggested to be due to its extremely potent angiogenesis and granulation tissue formation activities, leading to a rapid reepithelialization of the wound. Topical application of rhbFGF-F2 mixed with type I collagen is a more effective method in accelerating closure of full-thickness excisional skin-wound in diabetic rats when compared with the fusion protein alone or commercial hbFGF at the same doses. These studies advance the technology necessary to generate large quantities of targeted bFGF fusion proteins as well as to develop new strategies for specific biomedical applications.

Production of a recombinant human basic fibroblast growth factor with a collagen binding domain

Basic fibroblast growth factor (bFGF) is a potent in vitro mitogen for capillary endothelial cells, stimulates angiogenesis in vivo, and may participate in tissue repair. Basic FGF is found in abundance in tissues such as brain, kidney, and cartilage. This study reports the expression, purification, and renaturation of a biologically active human basic fibroblast growth factor fusion protein (hbFGF-F1) from Escherichia coli. A prokaryotic expression vector was engineered to produce a tripartite fusion protein consisting of a purification tag, a protease-sensitive linker and collagen binding domain, and a cDNA sequence encoding the active fragment of hbFGF. The expressed hbFGF-F1 and hbFGF-F2 (it contains the collagen binding domain), located in inclusion bodies, were solubilized with 6 M guanidine-HCl and renatured by a glutathione redox system and protracted dialysis under various experimental conditions. The purification of the recombinant proteins was achieved by binding the His-tag of the fusion protein on a nickel-nitrilotriacetic acid metal chelate column. The biological activity of the recombinant growth factor was demonstrated by its ability to stimulate proliferation of human vein endothelial cells, monitored by [3H]thymidine incorporation, where commercial recombinant human bFGF (rhbFGF) served as a positive control. Purified rhbFGF-F1 and rhbFGF-F2 constructs exhibited proliferative activity comparable to commercial rhbFGF. The high-affinity binding was demonstrated by the binding of [3H]collagen to the rhbFGF-F2 protein immobilized on a Ni-nitrilotriacetic acid column. The rhbFGF-F2 fusion protein bound to collagen-coated surfaces with high affinity. Taken together, these results demonstrate that biologically active rhbFGF fusion proteins can be recovered from transformed bacteria by oxidative refolding; thus, providing a means for their high-yield production, purification, and renaturation from microorganisms. Furthermore, we demonstrate that the auxiliary collagen binding domain effectively targets the recombinant growth factor to type I collagen. These studies advance the technology necessary to generate large quantities of targeted bFGF fusion proteins for specific biomedical applications.

The estimated rate of depressed mood in US adults: recent evidence for a peak in later life

OBJECTIVE

The main aim of this study is to add new evidence on the descriptive epidemiology of depressed mood, and to investigate suspected determinants for depressed mood in adulthood.

METHODS

The data are from a continuing survey of a nationally representative sample of adult household residents in the United States, conducted in 1995 and 1996, totaling 26,883 respondents. Multiple logistic regression procedures yielded estimated associations.

RESULTS

We found that an estimated 1.9% of adult females and 1.0% of adult males experience a spell of sustained depressed mood during a span of approximately 2 weeks duration (i.e. point prevalence). For most of these cases, this is not the first spell. Among women, the smoothed curve for the prevalence estimates shows a peak in the youngest age stratum and decreases across age strata before 60 years, and has a slight secondary peak thereafter. In contrast, for males, the prevalence estimates of depression show no peak in the older age strata. Evidence from logistic regression analyses supports the inference of this later life peak in frequency of depressed mood among women. These new findings add to a growing body of epidemiological evidence on age and depression, and provoke new questions about the possibly etiological relationships involving social structural characteristics of local neighborhoods in combination with individual-level risk factors that have received primary attention in recent psychiatric epidemiology.

CONCLUSIONS

These findings point to the need for further etiological research, including studies of relationships between social structural characteristics of local neighborhoods and the occurrence of spells of depressed mood, as well as clinical implications for depression mood in late life.

Characterization of the IncW cryptic plasmid pXV2 from Xanthomonas campestris pv. vesicatoria

The gram-negative plant pathogen Xanthomonas campestris pv. vesicatoria strain Xv2 harbors an indigenous, cryptic plasmid pXV2 of 14.6 kb. This plasmid can only be maintained in Xanthomonas and is incapable of self-transmission. However, incompatibility testing classified it in IncW, a group containing the smallest number of naturally occurring, broad-host-range, conjugative plasmids. A pXV2 derivative containing only a 5.5-kb PstI fragment is stably maintained. Deletion of a 3.0-kb region from the PstI fragment causes a loss of plasmid stability. Nucleotide sequencing of the 2. 1-kb region essential for autonomous replication revealed a repA gene and a downstream noncoding region containing four iterons, two 17- and two 19-nt direct repeats, and an AT-rich region lying between the two sets of iterons. The sequence of the deduced RepA and the iterons shows homology to the RepA (39% identity) and the iterons, respectively, of the IncW plasmid pSa. Maxicell expression of the repA gene produced a protein of 35 kDa, a size similar to that deduced from the nucleotide sequence. Trans-complementation test confirmed that the repA gene and the iterons are indeed the essential elements for pXV2 replication.

The use of the case-crossover design in studying illicit drug use

The case-crossover design was developed to study time-varying exposures that cause transient excess risk of acute health events. It is a variant of case-control and subject-as-own-control research designs, involving use of information about exposure history of each case to estimate the transient effect. This kind of self-control design can help to reduce sampling bias otherwise introduced in the selection of controls, as well as confounding bias that might be derived from enduring individual characteristics, especially personality traits and other long-standing inherited or acquired vulnerabilities. When the subject is used as his or her own control, these personal vulnerabilities are matched. In this paper we discuss strengths and weaknesses of the case-crossover design and suggest applications of the case-crossover design in epidemiologic studies on suspected hazards of illicit drug use, and in studies of drug use and co-occurring psychiatric disturbances. We conclude that the case-crossover design can play a useful role, but it discloses a need to secure fine-grained measurements in epidemiologic research on psychiatric comorbidity. As explained in the paper, we also believe the case-crossover method may be of use to criminologists who study the drugs-crime nexus, to services researchers and clinicians who seek to understand treatment entry and compliance behavior, and to etiologists interested in polydrug use.

Effects of caffeic acid, chlorogenic acid and ferulic acid on growth and arylamine N-acetyltransferase activity in Shigella sonnei (group D)

Arylamine N-acetyltransferase (NAT) activities with 2-aminofluorene (2-AF) as substrates were determined in Shigella sonnei (group D) collected from patients with diarrhoeal disease. The NAT activity was determined using an acetyl CoA recycling assay and high pressure liquid chromatography. Inhibition of growth studies from S. sonnei (group D) demonstrated that caffeic acid (CA), chlorogenic acid (CGA) and ferulic acid (FA) elicited a dose-dependent bactericidal effect in S. sonnei (group D) cultures, i.e. the greater the concentration of CA, CGA and FA, the greater the inhibition of growth of S. sonnei (group D). Cytosols or suspensions of S. sonnei (group D) with and without selected concentrations of CA, CGA and FA co-treatment showed different percentages of 2-AF acetylation. The data indicated that there was reduced NAT activity associated with increased CA, CGA and FA in Shigella dysenteriae (group D) cytosols and intact cells. For the cytosol and intact bacteria examinations, the apparent values of K(m) and Vmax decreased after being co-treated with 400 microM CA, CGA and FA. This report is the first demonstration of plant phenolic inhibition (CA, CGA and FA) of arylamine NAT activity and growth in the bacterium S. sonnei (group D).

Tobacco smoking and depressed mood in late childhood and early adolescence

OBJECTIVES

This study builds on previous observations about a suspected causal association linking tobacco smoking with depression. With prospective data, the study sheds new light on the temporal sequencing of tobacco smoking and depressed mood in late childhood and early adolescence.

METHODS

The epidemiologic sample that was studied consisted of 1731 youths (aged 8-9 to 13-14 years) attending public schools in a mid-Atlantic metropolitan area, who were assessed at least twice from 1989 to 1994. A survival analysis was used to examine the temporal relationship from antecedent tobacco smoking to subsequent onset of depressed mood, as well as from antecedent depressed mood to subsequent initiation of tobacco use.

RESULTS

Tobacco smoking signaled a modestly increased risk for the subsequent onset of depressed mood, but antecedent depressed mood was not associated with a later risk of starting to smoke tobacco cigarettes.

CONCLUSIONS

This evidence is consistent with a possible causal link from tobacco smoking to later depressed mood in late childhood and early adolescence, but not vice versa.

Panic attacks and suicide attempts in mid-adolescence

OBJECTIVE

The aim of this study was to investigate the association of panic attacks and suicide attempts in a community-based sample of 13-14-year-old adolescents.

METHOD

The data are from a survey of 1,580 students in an urban public school system located in the mid-Atlantic region of the United States. Logistic regression methods were used to estimate associations between panic attacks and suicidal ideation and suicide attempts.

RESULTS

Controlling for demographic factors, major depression, the use of alcohol, and the use of illicit drugs, the authors found that adolescents with panic attacks were three times more likely to have expressed suicidal ideation and approximately two times more likely to have made suicide attempts than were adolescents without panic attacks.

CONCLUSIONS

This new epidemiologic research adds to the evidence of an association between panic attacks and suicide attempts during the middle years of adolescence.

Effects of berberine on arylamine N-acetyltransferase activity in human colon tumor cells

Berberine was used to determine loss of viable cells and inhibition of arylamine Nacetyltransferase (NAT) activity in a human colon tumor (adenocarcinoma) cell line. The viable cells were determined by trypan blue exclusion under a light microscope. The NAT activity was measured by high performance liquid chromatography for the amounts of N-acetyl-2-aminofluorene (AAF), N-acetyl-p-aminobenzoic acid (N-Ac-PABA), and the remaining 2-aminofluorene (AF) and p-aminobenzoic acid (PABA). The viability and NAT activity in a human colon tumor cell line was inhibited by berberine in a dose-dependent manner, i.e., the higher the concentration of berberine, the higher the inhibition of NAT activity and cell death. The NAT activities measured in the intact human colon tumor cells were decreased over 50% by AAF and NAc-PABA production from acetylation of AF and PABA. The apparent values of Kmoff and Vmax of NAT from colon tumor cells were also inhibited by berberine in cytosols and in intact cells. This report is the first to show that berberine did affect human colon tumor cell NAT activity.

Influence of comorbid alcohol and psychiatric disorders on utilization of mental health services in the National Comorbidity Survey

OBJECTIVE

This study sought to determine how comorbidity of psychiatric and substance abuse disorders affects the likelihood of using mental health services.

METHOD

The analysis was based on data on adults aged 18-54 years in the National Comorbidity Survey (N = 5,393). Users and nonusers of mental health and substance abuse services were compared in terms of their demographic characteristics, recent stressful life events, social support, parental history of psychopathology, self-medication, and symptoms of alcohol abuse/dependence.

RESULTS

The prevalence of service utilization varied by diagnostic configurations. Comorbid psychiatric or alcohol disorders were stronger predictors of service utilization than a pure psychiatric or alcohol disorder. Factors predicting utilization of services differed for each disorder.

CONCLUSIONS

Since comorbidity increases the use of mental health and substance abuse services, research on the relationship of psychiatric and alcohol-related disorders to service utilization needs to consider the coexistence of mental disorders. Attempts to reduce barriers to help seeking for those in need of treatment should be increased.

Tobacco smoking and other suspected antecedents of nonmedical psychostimulant use in the United States, 1995

This study investigates the extent to which tobacco smoking is associated with the nonmedical use of psychostimulants and the temporal order of the age of first use for tobacco and psychostimulants within a nationally representative sample of United States household residents. At the same time, alcohol use and other suspected determinants of psychostimulant use are investigated and held constant, using multiple regression models. Data were taken from public use files of the 1995 National Household Survey on Drug Abuse. Conditional logistic regression analyses were performed to derive estimated relative odds of using stimulants for tobacco smokers versus nonsmokers, holding constant other potentially distorting influences. This study provides recent evidence on tobacco smoking as one of the potentially malleable risk factors for the nonmedical use of stimulant drugs.

Effects of berberine on arylamine N-acetyltransferase activity in human bladder tumour cells

Berberine was used to determine inhibition of arylamine N-acetyltransferase (NAT) activity in human bladder tumour cells. The NAT activity was measured by HPLC assaying for the amounts of N-acetyl-2-aminofluorene (AAF) and N-acetyl-p-aminobenzoic acid (N-Ac-PABA) and remaining 2-aminofluorene (AF) and p-aminobenzoic acid (PABA). Two assay systems were performed, one with cellular cytosols, the other with intact bladder tumour cell suspensions. The NAT activity in human bladder tumour cells was inhibited by berberine in a dose-dependent manner, that is, the higher the concentration of berberine, the higher the inhibition of NAT activity. The values of apparent Km and Vmax calculated from cytosol NAT and intact cells were also decreased by berberine. This report is the first demonstration to show berberine did affect human bladder tumour cell NAT activity.

Effects of garlic compounds diallyl sulfide and diallyl disulfide on arylamine N-acetyltransferase activity in strains of Helicobacter pylori from peptic ulcer patients

Arylamine N-acctyltransferase (NAT) activities with p-aminobenzoic acid (PABA) and 2-aminofluorene (2-AF) were determined in the bacterium Helicobacter pylori collected from peptic ulcer patients. Two assay systems were performed, one with cellular cytosols, the other with intact cell suspensions. Cytosols or suspensions of H. pylori with or without specific concentrations of diallyl sulfide (DAS) or diallyl disulfide (DADS) co-treatment showed different percentages of 2-AF and PABA acetylation. The data indicated that there was decreased NAT activity associated with increased levels of DAS or DADS in H. pylori cytosols and suspensions. Viability studies on H. pylori demonstrated that DAS or DADS elicited dose-dependent bactericide affects on H. pylori cultures. The data also indicated that DAS and DADS decreased the apparent values of K(m) and Vmax of NAT enzyme from H. pylori in both systems examined. This report is the first demonstration that garlic components can affect H. pylori growth and NAT activity.

Characterization of arylamine N-acetyltransferase in Enterobacter aerogenes

N-acetyltransferase (NAT) activity was determined by incubation of purified Enterobacter aerogenes enzyme with 2-aminofluorene (2-AF) as the substrate, followed by high pressure liquid chromatography assays. The NAT activity from E. aerogenes was 0.58 +/- 0.08 nmol/min/mg protein for 2-AF. The values of apparent K(m) and Vmax were 0.72 +/- 0.14 mM and 2.45 +/- 0.29 nmol/min/mg protein, respectively, for 2-AF. The optimal pH value for the enzyme activity was 7.5 for the 2-AF tested. The optimal temperature for enzyme activity was 37 degrees C for the 2-AF substrate. The molecular weight of NAT from E. aerogenes was 44.9 kD. Among a series of divalent cations and salts, Zn2+, Ca2+, and Fe2+ were demonstrated to be the most potent protease inhibitors, and only ethylenediaminetetraacetic acid significantly protected the NAT. Iodoacetamide, in contrast to other agents, markedly inhibited NAT.