Effects of sub-inhibitory concentrations of nafcillin, vancomycin, ciprofloxacin, and rifampin on biofilm formation of clinical methicillin-resistant Staphylococcus aureus

Methicillin-resistant Staphylococcus aureus (MRSA) infections are often difficult to treat because of their biofilm-forming ability and antimicrobial resistance. We investigated the effects of sub-minimal inhibitory concentrations (MICs) of antibiotics on MRSA biofilm formation. Clinical MRSA isolates were grown with sub-MICs (1/256-1/2 × MICs) of nafcillin, vancomycin, ciprofloxacin, and rifampin. The biofilm biomass was measured using crystal violet staining. Of the 107 MRSA isolates tested, 63 (58.9%) belonged to sequence type 5 (ST5), and 44 (41.1%) belonged to ST72. The MIC50/MIC90 values of nafcillin, vancomycin, ciprofloxacin, and rifampin were 256/512, 1/2, 64/512, and 0.008/0.03 mg/L, respectively. The sub-MICs of nafcillin, vancomycin, ciprofloxacin, and rifampin promoted biofilm formation in 75 (70.1%), 49 (45.8%), 89 (83.2%), and 89 (83.2%) isolates, respectively. At sub-MICs of nafcillin, the factors associated with strong biofilm induction were the ST5 strain (P = 0.001) and agr dysfunction (P = 0.005). For the sub-MICs of ciprofloxacin, the associated factors were the ST5 strain (P = 0.002), staphylococcal protein A type t002 strain (P < 0.001), and ciprofloxacin resistance (P < 0.001). Among the sub-MICs of rifampin, only ST5 was associated with strong biofilm induction (P = 0.006). Because the sub-MICs of rifampin were much lower than clinically relevant concentrations, we further tested the capability of biofilm induction in 0.03[Formula: see text]32 mg/L of rifampin. At these concentrations, rifampin-induced biofilm formation was rare in rifampin-susceptible MRSA [1.0% (1 of 100)] but common in rifampin-resistant MRSA [71.4% (5 of 7), P < 0.001]. Induction of biofilm biomass at sub-MICs of antibiotics is common in clinical MRSA isolates and is differentially affected by the MRSA strain and antibiotic class.

IMPORTANCE

Bacteria can be exposed to sub-MICs of antibiotics at the beginning and end of a dosing regimen, between doses, or during low-dose therapies. Growing evidence suggests that sub-MICs of antimicrobials can stimulate MRSA biofilm formation and alter the composition of the biofilm matrix. Pevious studies have found that sub-MICs of oxacillin, methicillin, and amoxicillin promote biofilm formation in some community-acquired MRSA (CA-MRSA). We evaluated biofilm induction by sub-MICs of four different classes of antibiotics in 44 CA-MRSA and 63 healthcare-associated MRSA (HA-MRSA) strains. Our study indicated that sub-MICs of nafcillin, vancomycin, ciprofloxacin, and rifampin frequently promote biofilm induction in clinical MRSA isolates. Strong biofilm induction in sub-MICs of nafcillin, ciprofloxacin, and rifampin was more frequent in HA-MRSA than in CA-MRSA. Antibiotic-induced biofilm formation depends on the antibiotic class, MRSA strain, and antibiotic resistance. Our results emphasize the importance of maintaining effective bactericidal concentrations of antibiotics to treat biofilm-related infections.

Real-world comparison between mechanical and manual cardiopulmonary resuscitation during the COVID-19 pandemic

BACKGROUND

The COVID-19 pandemic has posed significant challenges to healthcare systems worldwide, including an increase in out-of-hospital cardiac arrests (OHCA). Healthcare providers are now required to use personal protective equipment (PPE) during cardiopulmonary resuscitation (CPR). Additionally, mechanical CPR devices have been introduced to reduce the number of personnel required for resuscitation. This study aimed to compare the outcomes of CPR performed with a mechanical device and the outcomes of manual CPR performed by personnel wearing PPE.

METHODS

This multicenter observational study utilized data from the Korean Cardiac Arrest Research Consortium registry. The study population consisted of OHCA patients who underwent CPR in emergency departments (EDs) between March 2020 and June 2021. Patients were divided into two equal propensity score matched groups: mechanical CPR group (n = 421) and PPE-equipped manual CPR group (n = 421). Primary outcomes included survival rates and favorable neurological outcomes at discharge. Total CPR duration in the ED was also assessed.

RESULTS

There were no significant between-group differences with respect to survival rate at discharge (mechanical CPR: 7.4% vs PPE-equipped manual CPR: 8.3%) or favorable neurological outcomes (3.3% vs. 3.8%, respectively). However, the mechanical CPR group had a longer duration of CPR in the ED compared to the manual CPR group.

CONCLUSION

This study found no significant differences in survival rates and neurological outcomes between mechanical CPR and PPE-equipped manual CPR in the ED setting. However, a longer total CPR duration was observed in the mechanical CPR group. Further research is required to explore the impact of PPE on healthcare providers' performance and fatigue during CPR in the context of the pandemic and beyond.

Cytokine and Chemokine Profiles in Acute Severe Fever with Thrombocytopenia Syndrome and Scrub Typhus in South Korea

In East Asia, severe fever with thrombocytopenia syndrome (SFTS) and scrub typhus, which are common endemic tick- and mite-mediated diseases sharing common clinical manifestations, are becoming public health concerns. However, there are limited data on the comparative immunopathogenesis between the two diseases. We compared the cytokine profiles of SFTS and scrub typhus to further elucidate immune responses that occur during the disease courses. We prospectively enrolled 44 patients with confirmed SFTS and 49 patients with scrub typhus from July 2015 to December 2020. In addition, 10 healthy volunteers were enrolled as healthy controls. A cytometric bead array was used to analyze plasma samples for 16 cytokines. A total of 68 plasma samples, including 31 (45.6%) from patients with SFTS and 37 (54.4%) from patients with scrub typhus, were available for cytokine measurement. There were three cytokine expression patterns: increased levels in both SFTS and scrub typhus (interleukin 6 [IL-6], IL-10, interferon gamma induced protein 10 [IP-10], and granulocyte-macrophage colony-stimulating factor [GM-CSF]), highest levels in SFTS (interferon alpha [IFN-α], IFN-γ, granulocyte-CSF [G-CSF], monocyte chemotactic protein 1 [MCP-1], macrophage inflammatory protein 1α [MIP-1α], and IL-8), and distinct levels in scrub typhus (IL-12p40, tumor necrosis factor alpha [TNFα], IL-1β, regulated on activation and normally T-cell expressed and secreted [RANTES], IL-17A, and vascular endothelial growth factor [VEGF]). Although patients with acute SFTS and scrub typhus exhibited partly shared expression patterns of cytokines related to disease severity, the different profiles of cytokines and chemokines might contribute to higher mortality in SFTS than in scrub typhus. Discrete patterns of helper T cell-related cytokines and VEGF might reflect differences in CD4 T-cell responses and vascular damage between these diseases.

Fabrication of Ce doped TiO2 for efficient organic pollutants removal from wastewater

Pristine and Ce doped TiO₂ nanoparticles were fabricated for toxic pollutants removal from wastewater. Pristine, 2% Ce and 4% Ce doped TiO₂ photocatalysts were produced via hydrothermal route. 4% Ce doped TiO₂ exhibited 2.41 eV bandgap which is smaller than pure TiO_2. The morphology was also investigated and it was established that doping of Ce ions enhanced the surface roughness and reduced the particle size. The surface area was characterized through BET analysis and 4% Ce-TiO₂ possess higher surface with large pore diameter which helped the photocatalytic activity. The prepared photocatalysts were investigated on reduction of pollutants from wastewater under visible light. Higher efficiency was obtained for 4% Ce-TiO₂ photocatalyst for both model pollutants. The "k" value possessed was also higher for the doped TiO₂ catalyst. These analysis reports the optimum level of ceria doping to enhance morphology, surface area and it increased activity than bare TiO₂. 4% Ce-TiO₂ will be the potential candidate for efficient wastewater management. The 4% Ce doped TiO₂ photocatalyst provided 77% and 88% on reducing MB and RhB dyes. The dopant has developed higher surface area, morphology and good recombination rate which reduced the toxic pollutants and changed the wastewater to reuse.

Investigation of PEG directed Sb2WO6 for dyes removal from wastewater

Pristine and polyethylene glycol assisted antimony tungstate (Sb₂WO₆) was developed via hydrothermal route. The pristine and surfactant assisted Sb₂WO₆ were further exemplified to reveal the properties of the samples. The bandgap calculated for Sb₂WO₆, 5 ml PEG- Sb₂WO₆, 10 ml PEG- Sb₂WO₆ was 2.78 eV, 2.66 eV and 2.21 eV. The 10 ml PEG assisted sample exhibited narrow bandgap. The Fourier transform infrared spectroscopy (FTIR) spectra of the samples showed metal vibrations and stretching of the water molecules adsorbed. The Raman spectra showed the vibrational modes present in Sb₂WO₆. The morphology was analyzed employing transmission electron microscope (TEM) for all samples. Pristine Sb₂WO₆ showed growth of nanorods with higher dimensions with high agglomeration. 5 ml PEG- Sb₂WO₆ showed the growth of nanorods with lesser agglomeration. 10 ml PEG assisted Sb₂WO₆ exhibited distinct growth of nanorods with no agglomeration on the surface. The elemental composition was examined employing X-ray Photoelectron Spectroscopy. Prepared product photocatalytic behaviour was tested employing Rhodamine B dye degrading. Different catalyst loading were investigated for degrading the toxic pollutants. 0.2 g 10 ml PEG-Sb₂WO₆ showed 81% efficiency on degrading the toxic pollutant from wastewater. The OH radicals are accountable for photocatalytic behaviour of prepared photocatalyst. The 10 ml PEG-Sb₂WO₆ has the good reusability behavior and stable properties after three cycles. The prepared 10 ml PEG- Sb₂WO₆ photocatalyst will be the potential candidate for the remediation of the water treatment.

Real World Experience with Regdanvimab Treatment of Mild-to-Moderate Coronavirus Disease-19 in a COVID-19 Designated Hospital of Korea

Background

Real-world clinical data concerning regdanvimab, a monoclonal antibody treatment for patients with mild-to-moderate coronavirus disease 2019 (COVID-19), are urgently needed. Here, we describe our experience with regdanvimab.

Materials and Methods

This retrospective cohort study enrolled high-risk adults with mild-to-moderate COVID-19 who were admitted to a dedicated COVID-19 hospital in Korea from March to September 2021. We used multiple logistic regression and propensity score-matching to compare the outcomes of patients who did or did not receive regdanvimab. The primary outcome was in-hospital progression to severe or critical status, or death.

Results

Of 586 patients eligible for regdanvimab, 256 patients who received regdanvimab and 251 untreated patients were included. The median age was 66 years and 47.5% were men. The most common underlying illnesses were hypertension (53.8%) and diabetes (36.9%). Patients were admitted to the hospital at a median of 2 days after symptom onset; regdanvimab was administered at a median of 3 days after symptom onset. Multivariate analysis indicated that regdanvimab significantly reduced the risk of disease progression during hospitalization [odds ratio (OR): 0.285; 95% confidence interval (CI): 0.144 - 0.564]. In a 1:1 propensity score-matched cohort (172 patients in either group), regdanvimab also decreased the risk of progression (OR: 0.162; 95% CI: 0.068 - 0.386).

Conclusion

In high-risk patients with mild-to-moderate COVID-19, regdanvimab decreased the risk of progression to severe COVID-19.

Investigation of pure and g-C3N4 loaded CdWO4 photocatalytic activity on reducing toxic pollutants

A facile synthesis of pristine and g-C₃N₄ loaded CdWO₄ (Cadmium Tungstate) were reported and analyzed the effect of pollutants removal in wastewater. The samples were characterized and the morphology of the pristine sample showed the nanostructures with high cluster of layer formed. While adding PEG (Polyethylene glycol), the surface has exhibited less agglomeration and in g-C₃N₄ added sample the agglomeration was intensely reduced and nanostructures have been clearly found. Photocatalytic performance on cationic dye was investigated under visible light. The efficiency calculated for g-C₃N₄- CdWO₄ sample was 85% for MB. The C/C₀ plot gives better degradation. The kinetic study revealed pseudo first order reaction. The g-C₃N₄-CdWO₄ sample exhibited higher "k" value which proved best efficiency on removing the pollutant. g-C₃N₄-CdWO₄ sample will make better reduction on toxic pollutants and be a good candidate in futuristic applications. By carbon based derivates inclusion with photo active materials, the morphology and surface area was greatly improved and it enhances activity of host material and it will be the promising material for industrial applications.

Clinical Features of Adult COVID-19 Patients without Risk Factors before and after the Nationwide SARS-CoV-2 B.1.617.2 (Delta)-variant Outbreak in Korea: Experience from Gyeongsangnam-do

BACKGROUND

Data on severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) delta variant virulence are insufficient. We retrospectively compared the clinical features of adult coronavirus disease 2019 (COVID-19) patients without risk factors for severe COVID-19 who entered residential treatment centers (RTCs) before and after the delta variant outbreak.

METHODS

We collected medical information from two RTCs in South Korea. On the basis of nationwide delta variant surveillance, we divided the patients into two groups: 1) the delta-minor group (diagnosed from December 2020-June 2021, detection rate < 10%) and 2) the delta-dominant group (diagnosed during August 2021, detection rate > 90%). After propensity-score matching, the incidences of pneumonia, hospital transfer and need for supplemental oxygen were compared between the groups. In addition, risk factors for hospital transfer were analysed.

RESULTS

A total of 1,915 patients were included. The incidence of pneumonia (14.6% vs. 9.2%, P = 0.009), all-cause hospital transfer (10.4% vs. 6.3%, P = 0.020) and COVID-19-related hospital transfer (7.5% vs. 4.8%, P = 0.081) were higher in the delta-dominant group than those in the delta-minor group. In the multivariate analysis, the delta-dominant group was an independent risk factor for all-cause (adjusted odds ratio [aOR], 1.91; 95% confidence interval [CI], 1.16-3.13; P = 0.011) and COVID-19-related hospital transfer (aOR, 1.86; 95% CI, 1.04-3.32; P = 0.036).

CONCLUSION

Hospitalization rates were increased in the adult COVID-19 patients during the delta variant nationwide outbreak. Our results showed that the delta variant may be more virulent than previous lineages.

Risk factors for isolation of multi-drug resistant organisms in coronavirus disease 2019 pneumonia: A multicenter study

Objectives

Superimposed multi-drug resistant organisms (MDROs) co-infection can be associated with worse outcomes in patients with severe coronavirus disease 2019 (COVID-19), even if these patients were managed with strict airborne and contact precautions. Identifying risk factors for isolation of MDROs is critical to COVID-19 treatment.

Methods

All eligible adult patients with confirmed COVID-19 pneumonia from 10 hospitals in the Republic of Korea between February 2020 and May 2020 were retrospectively enrolled. Using this cohort, epidemiology and risk factors for isolation of MDROs were evaluated.

Results

Of 152 patients, 47 with microbial culture results were included. Twenty isolates of MDROs from 13 (28%) patients were cultured. Stenotrophomonas maltophilia (5 isolates) was the most common MDRO, followed by methicillin-resistant staphylococcus aureus (4 isolates). MDROs were mostly isolated from sputum samples (80%, 16/20). The median time from hospitalization to MDRO isolation was 28 days (interquartile range, 18-38 days). In-hospital mortality was higher in patients with MDRO isolation (62% vs 15%; P = .001). Use of systemic corticosteroids after diagnosis of COVID-19 (adjusted odds ratio [aOR]: 15.07; 95% confidence interval [CI]: 2.34-97.01; P = .004) and long-term care facility (LTCF) stay before diagnosis of COVID-19 (aOR: 6.09; 95% CI: 1.02-36.49; P = .048) were associated with MDRO isolation.

Conclusions

MDROs were isolated from 28% of COVID-19 pneumonia patients with culture data and 8.6% of the entire cohort. Previous LTCF stay and adjunctive corticosteroid use were risk factors for the isolation of MDROs. Strict infection prevention strategies may be needed in these COVID-19 patients with risk factors.

Response System for and Epidemiological Features of COVID-19 in Gyeongsangnam-do Province in South Korea

BACKGROUND

The South Korean government has been combating the coronavirus disease 2019 (COVID-19) outbreak using public information and extensive viral screening. We describe the application of the Korean response system in Gyeongsangnam-do province and outline the epidemiological features of COVID-19 in the cohort.

METHODS

A Rapid Response Team tracked the patients' activities and identified close contacts. A Patient Management Team made decisions regarding the severity of illness, hospital allocation depending on severity, and time of discharge. A national medical center with 155 beds and 4 university-affiliated hospitals with 48 negative-pressure isolation rooms were dedicated for patients with COVID-19.

RESULTS

As of 15 April, 17 400 residents were tested, of whom 111 were confirmed positive cases. Of the 111 patients, 78 were cured and discharged, 2 recovered after mechanical ventilation, and none died. One healthcare worker at the national center tested positive for SARS-CoV-2. All 412 staff members at the center were tested, but there were no additional infections. Cough (30.0%) was the most common initial symptom, whereas anosmia and ageusia were the first symptoms in 14.7% and 15.7% of the patients, respectively. Overall, 25 patients (22.5%) reported having no symptoms at admission and 7 (6.3%) remained asymptomatic at discharge.

CONCLUSIONS

A response system that enabled the early detection of COVID-19 cases, including asymptomatic and presymptomatic cases, and timely quarantine of these patients and their contacts, along with efficient allocation of medical resources, was the key to curbing the COVID-19 outbreak in Gyeongsangnam-do Province.

Veno-Arterial-Venous Extracorporeal Membrane Oxygenation in a Critically Ill Patient with Coronavirus Disease 2019

Patients with cardiopulmonary failure may not be fully supported with typical configurations of extracorporeal membrane oxygenation (ECMO), either veno-arterial (VA) or veno-venous (VV). Veno-arterial-venous (VAV)-ECMO is a technique used to support the cardiopulmonary systems during periods of inadequate gas exchange and perfusion. In the severe case of coronavirus disease 2019 (COVID-19), which simultaneously affects the heart and lung, VAV-ECMO may improve a patient's recovery potential. We report the case of a 72-year-old woman with acute respiratory distress syndrome and circulatory failure following COVID-19, who was treated with VAV-ECMO.

Preterm Twins Born to a Mother with Miliary Tuberculosis: Importance of Early Recognition and Prompt Response in Infection Control to Manage Congenital Tuberculosis Exposure in a Neonatal Intensive Care Unit

Delayed diagnosis of congenital tuberculosis (TB) in the neonatal intensive care unit (NICU) is a serious problem in terms of infection control. Here, we report our preemptive infection control activities implemented after the diagnosis of miliary TB in a mother of preterm twins (index twins, NB1 and NB2) in the NICU. In addition, we reviewed previous case reports of congenital TB exposure in the NICU setting. Immediately after diagnosing miliary TB in the mother, the index twins were isolated before their TB diagnosis and received preemptive anti-TB medication; contact investigations were also conducted. Eventually, NB1 was diagnosed with congenital TB at 29 days of age, and NB2 showed no definite evidence of TB. Through contact investigation, 11 of the 16 exposed infants received isoniazid prophylaxis and no positive tuberculin skin test results were obtained after 3 months. One of the 31 exposed healthcare workers showed new interferon-gamma release assay conversion. Moreover, our case showed a much shorter contagious period compared to that in previous reports (8 versus 17-102 days). This suggests that a high index of suspicion and prompt measures can help prevent congenital TB outbreaks and reduce the burden of infection control activities in the NICU.

Environmental contamination of SARS-CoV-2 during the COVID-19 outbreak in South Korea

Objectives

Although contact precaution is generally recommended in situations where coronavirus disease 2019 (COVID-19) is suspected, there is limited evidence on environmental contamination of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Therefore, we conducted environmental surveillance on SARS-CoV-2 contamination in 2 different healthcare settings.

Methods

Viral contamination was investigated on the environment of 2 hospitals that had admitted 13 COVID-19 patients. In hospital A, 5 patients with pneumonia occupied negative pressure rooms. In hospital B, 8 asymptomatic patients shared 2 common 4-bed rooms. Most rooms were poorly cleaned or disinfected. Environmental swab were collected from inside and outside the rooms and were tested using real-time RT-PCR for the detection of SARS-CoV-2.

Results

In hospital A, SARS-CoV-2 was detected in 10 of 57 (17.5%) samples from inside the rooms including the Ambu bag and infusion pump. Two samples obtained at more than 2 m from the patients showed positive results. In hospital B, 3 of 22 (13.6%) samples from inside the rooms were positive. Areas outside the rooms, such as the anteroom, corridor, and nursing station, were all negative in both hospitals.

Conclusions

Hospital surfaces surrounding patients were contaminated by SARS-CoV-2. Our findings support the value of strict contact precaution, routine cleaning, and disinfection in the management of COVID-19 patients.

Effects of subinhibitory concentrations of chlorhexidine and mupirocin on biofilm formation in clinical meticillin-resistant Staphylococcus aureus

BACKGROUND

The effects of subinhibitory concentrations (sub-MICs) of antibacterial agents on the biofilm-forming ability of Staphylococcus aureus require further study.

AIM

To investigate the effects of sub-MICs of chlorhexidine and mupirocin on biofilm formation in clinical meticillin-resistant Staphylococcus aureus (MRSA) isolates.

METHODS

MRSA isolates were collected from patients with bloodstream infections at a tertiary care hospital. The basal level of biofilm formation and biofilm induction by sub-MICs of chlorhexidine and mupirocin were evaluated by measuring biofilm mass stained with Crystal Violet.

FINDINGS

Of the 112 MRSA isolates tested, 63 (56.3%) and 44 (39.3%) belonged to sequence type (ST)5 and ST72 lineages, respectively, which are the predominant healthcare- and community-associated clones in South Korea. ST5 isolates were more likely to have chlorhexidine MIC ≥4 (73.0% vs 29.5%), resistance to mupirocin (23.8% vs 0%), agr dysfunction (73.0% vs 9.1%), and qacA/B gene (58.7% vs 2.3%) compared to ST72 isolates. The basal level of biofilm formation ability was frequently stronger in ST72 isolates compared to ST5 isolates (77.3% vs 12.7%). Sub-MICs of chlorhexidine and mupirocin promoted biofilm formation in 56.3% and 53.6%, respectively, of all isolates. Biofilm induction was more prevalent in ST5 isolates (85.7% for chlorhexidine, 69.8% for mupirocin) than in ST72 isolates (15.9% for chlorhexidine, 27.3% for mupirocin).

CONCLUSION

Sub-MICs of chlorhexidine and mupirocin promoted biofilm formation in half of the clinical MRSA isolates. Our results suggest that ST5 MRSA biofilm can be induced together with some other bacterial virulent factors following exposure to chlorhexidine, which might confer a survival advantage to this clone in the healthcare environment.

1165. Risk Factors for Bloodstream Infections During Extracorporeal Membrane Oxygenation (ECMO)

Background

Although bloodstream infections (BSIs) are important complications of ECMO, data on clinical characteristics of ECMO-associated BSIs remain limited. This study aimed to investigate clinical characteristics of ECMO-associated BSIs and evaluate the role of routine active surveillance cultures (ASCs) in predicting subsequent BSIs.

Methods

We reviewed the medical records of adult patients who received ECMO for >48 hours in 2 teaching hospitals between January 2013 and March 2019. ECMO-associated BSIs were defined as bacteremia occurring from 48 hours after ECMO initiation. ASCs for multidrug-resistant organisms were obtained from nasal, axillary, inguinal, and rectal swabs when patients were admitted to the ICUs.

Results

Overall, 28 of 110 (25.4%) patients had BSIs within the median 7 days after ECMO initiation. Table 1 shows the clinical characteristics of patients with ECMO-associated BSIs. Among BSI cases, the most common pathogens were Candida spp. (25%). Longer ECMO days (P < 0.01), steroid use (P = 0.02), and more blood transfusions (P < 0.01) were associated with BSIs. However, there was no association between the results of ASCs and subsequent pathogens of BSIs.

Conclusion

BSIs during ECMO were associated with longer ECMO duration, steroid use and blood transfusion. The pathogens of BSIs could not be related to ASCs.

Disclosures

All authors: No reported disclosures.

Organic Datura metel Leaf Extract Mediated Inorganic Rare Earth La₂O₃ Nanocrystals Formation

Development of sustainable synthesis of La₂O₃ nanocrystals formation employing Datura metel leaf extract was explored. The obtained nanocrystals were analyzed employing XRD, Raman, PL, FTIR, XPS and TEM characterizations. With increasing incubation and aging, the transformation of La(OH)₃ to LaOOH and metal ellagate complex formation to La₂O₃ nanocrystals formation was observed. The obtained XRD results clearly revealed the transformation of lanthanum hydroxide to lanthanum oxide hydroxide and then to lanthanum oxide nanocrystals formation with 1, 4 and days. The influence of incubation and aging on La₂O₃ nanocrystals formation was discussed. Datura metel leaf extract product mixture over a period of incubation formed pure hexagonal lanthanum oxide nanocrystals.

Successful Treatment of Catheter Related Blood Stream Infection By Millerozyma farinosa with Micafungin: A Case Report

Millerozyma farinosa (formerly Pichia farinosa) is halotolerant yeast mainly found in food and ubiquitous in the environment. It was a rare yeast pathogen, but it has recently emerged as a cause of fungemia in immunocompromised patients. Optimal therapy for invasive fungal infection by this pathogen remains unclear. We report a case of catheter related blood stream infection caused by M. farinosa in a 71-year-old patient who recovered successfully after removal of the central venous catheter and treatment with micafungin.

Management of carbapenem-resistant Acinetobacter baumannii epidemic in an intensive care unit using multifaceted intervention strategy

BACKGROUND/AIMS

We evaluated the effects of a multifaceted intervention for controlling a carbapenem-resistant Acinetobacter baumannii (CRAB) epidemic in an intensive care unit (ICU) with no restrictions on carbapenem use.

METHODS

This study was conducted in a medical ICU between April 2012 and June 2016. The baseline infection control programs included surveillance cultures, contact precautions, and environmental cleaning. However, increases in the detection of CRAB isolates beginning in May 2013 led to the implementation of a new protocol, consisting of universal glove and gown use with daily chlorhexidine bathing for all patients in combination with baseline programs. The efficacy of the intervention was subjected to interrupted time series (ITS) analysis.

RESULTS

The multifaceted intervention led to a decrease in the incidence of CRAB from 17.65 to 0.89 cases per 1,000 patient-days, during the study period (p < 0.001). ITS analysis revealed a significant change in the trend of CRAB incidence (-0.413, p < 0.001). Over this same period, mean monthly use of carbapenems increased from 143.54 ± 95.73 to 204.95 ± 78.43 doses per 1,000 patient-days (p = 0.018).

CONCLUSION

Our multifaceted intervention reduced the incidence of CRAB acquisition in an ICU where carbapenem use was not restricted.

Prevalence and Microbiological Characteristics of qacA/B-Positive Methicillin-Resistant Staphylococcus aureus Isolates in a Surgical Intensive Care Unit

The increasing use of chlorhexidine for methicillin-resistant Staphylococcus aureus (MRSA) decolonization has raised concerns about the emergence of resistance to or tolerance of this antiseptic. We examined the frequency and characteristics of qacA/B chlorhexidine tolerance genes among MRSA isolates in a surgical intensive care unit (ICU) where MRSA-colonized patients are decolonized by chlorhexidine bathing. The MRSA isolates were evaluated for chlorhexidine susceptibility, mupirocin resistance, molecular typing, agr functionality, and the heterogeneous vancomycin-intermediate S. aureus (hVISA) phenotype according to the presence of the qacA/B genes. Overall, 119 MRSA isolates were obtained from active surveillance cultures (93, 78.2%) and clinical cultures (26, 21.8%) between 2012 and 2014. Among these isolates, 39 (32.8%) carried the qacA/B genes, and 23 (19.3%) exhibited mupirocin resistance. Most qacA/B-positive isolates (36/39, 92.3%) were identified as ST5-SCCmecII (69.2%) and ST239-SCCmecIII (23.1%), which are common healthcare-associated (HA)-MRSA strains in Korea. Multivariate analysis found that qacA/B-positive MRSA isolates were associated with agr dysfunction (OR, 4.87; 95% CI, 1.71-13.87) and the hVISA phenotype (OR, 4.09; 95% CI, 1.48-11.34). In conclusion, our study showed that qacA/B carriage was common among MRSA isolates in an ICU where chlorhexidine is commonly used for decolonization. qacA/B carriage was significantly associated with agr dysfunction and the hVISA phenotype. These features may confer a selective advantage on HA-MRSA strains, including ST5-SCCmecII and ST239-SCCmecIII, in the ICU setting.

A novel flexible drill device enabling arthroscopic transosseous repair of Bankart lesions

We have developed a flexible drill device that makes arthroscopic transosseous repair possible, and report preliminary results. Twelve patients with post-traumatic anterior inferior glenohumeral instability were selected.

SURGICAL TECHNIQUE

the flexible drill device is inserted into the shoulder joint through the posterior portal and the guide pipe unit is placed 5mm posterior to the margin of the anterior glenoid rim. The flexible drill is driven through the glenoid with the power drill, creating a hole in the glenoid. A non-absorbable suture is passed through the hole and a sliding knot tying is performed over the capsule and labrum after completing stitches with the suture hook loaded. The same procedures are repeated in the 2, 3 and 4 o'clock positions of the glenoid. There was no recurrence of dislocation at the mean follow-up period of 52.3 months. The mean Rowe score was 89.5.

Tuberculous Meningitis-Mimicking Varicella-Zoster Meningitis

Background

Varicella-zoster virus (VZV) is one of the most common etiologies of aseptic meningitis. The severest manifestation of VZV meningitis is occasionally confused with tuberculous meningitis (TBM). Thus, we investigated the clinical manifestations of VZV meningitis as compared with those of TBM.

Materials and Methods

All adult patients who were diagnosed with VZV meningitis or TBM were enrolled at a tertiary hospital in Seoul, South Korea, during an 8-year period. The clinical characteristics and cerebrospinal fluid (CSF) profile of patients were analyzed.

Results

Seventy-nine patients with VZV meningitis and 24 patients with TBM were enrolled in this study. Of the 79 patients with VZV meningitis, 63 (80%) did not received empirical anti-tuberculous therapy (Group 1) and the remaining 16 (20%) received empirical anti-tuberculous therapy (Group 2), compared with 24 patients with TBM (Group 3). Altered mental status, intensive care unit (ICU) admission, neurologic sequelae, CSF protein levels, and CSF adenosine deaminase levels revealed a trend of being higher in Group 3 than Group 2, which was higher than Group 1. However, the CSF/serum glucose ratio was significantly lower in Group 3 than in Group 1 or Group 2.

Conclusion

About one fifth of VZV meningitis cases presented as severe manifestations, mimicking TBM. The CSF/serum glucose ratio might be useful to differentiate VZV meningitis from TBM until definite diagnostic tests are available. Physicians should keep in mind that a differential diagnosis between severe VZV meningitis and TBM is needed.

Sensitivity of the Cytomegalovirus Antigenemia Assay to Diagnose Cytomegalovirus Retinitis

Background

Cytomegalovirus (CMV) retinitis is one of the most important tissue-invasive CMV diseases in immunocompromised patients. Since 1980, non-invasive diagnostic methods, notably the CMV antigenemia assay, have been widely used as adjunct tests to diagnose tissue-invasive CMV diseases. However, there are limited data on the diagnostic value of the CMV antigenemia assay for diagnosing CMV retinitis.

Materials and Methods

We performed a retrospective review of all cases of CMV retinitis at Asan Medical Center, Seoul, South Korea over a 9-year period. The diagnosis of CMV retinitis was made by experienced ophthalmologists according to medical history and an ophthalmoscopic appearance of typical retinopathy, together with absence of an alternative diagnosis.

Results

We analyzed 44 patients with CMV retinitis (affecting 57 eyes) for whom the CMV antigenemia assay was performed. Of the 44 patients, 31 (70%) were HIV-uninfected and 13 (30%) were HIV-infected. The overall sensitivity of the CMV antigenemia assay was 66% (95% confidence interval [CI] 50–80%). The test’s sensitivity showed a non-significant trend towards being higher in HIV-infected patients than in HIV-uninfected patients (sensitivity 85% vs 58%, respectively, P = 0.16). In a subgroup analysis of the 35 patients without other concurrent tissue-invasive CMV disease, the sensitivity of the CMV antigenemia assay was 57% (95% CI 40–74%).

Conclusions

The CMV antigenemia assay has limited value as a non-invasive diagnostic adjunct test for CMV retinitis. Therefore, the results of the assay need to be interpreted in the context of underlying disease, clinical presentation, and ophthalmoscopic findings.

Structural and toxic effect investigation of vanadium pentoxide

A facile inorganic complex synthesis route has been developed to synthesis V2O5 nanostructures. The effects of varying incubation time on the crystallinity and morphology of the V2O5 phase has been investigated. The obtained XRD result clearly revealed the pure orthorhombic V2O5 crystalline phase. Raman antiphase bridging VO and chaining VO stretching modes peaks at 686 and 521cm(-1) attributed orthorhombic V2O5 characteristics. The V2p3/2 peak at the binding energies of 517eV and V2p1/2 peak at 524eV assigned to V(5+) oxidation state. Bioinspired V2O5 nanostructures as a biocompatible material for anticancer agents show excellent cytotoxicity at higher V2O5 concentration.

Clinical Features and Outcomes of Spontaneous Bacterial Peritonitis Caused by Streptococcus pneumoniae: A Matched Case-Control Study

Streptococcus pneumoniae is a well-known cause of spontaneous bacterial peritonitis (SBP) in cirrhotic patients. However, little information is available regarding clinical characteristics and outcomes of SBP caused by S. pneumoniae. It has been suggested that spontaneous pneumococcal peritonitis (SPP) often spreads hematogenously from concomitant pneumococcal pneumonia, and is associated with a higher rate of mortality.During the period between January 1997 and December 2013, 50 SPP cases were identified. These cases were then age/sex-matched with 100 patients with SBP due to causes other than S. pneumoniae (controls).SPP accounted for 4.3% (50/1172) of all culture-proven SBPs. The baseline Child-Pugh class, etiology of cirrhosis, and model for end-stage liver disease scores were comparable for the 2 groups. SPP patients were more likely than control patients to have a community-acquired infection (90.0% vs. 76.0%; P = 0.04), concurrent bacteremia (84.0% vs. 59.0%; P = 0.002), and to present with variceal bleeding (10.0% vs. 1.0%; P = 0.02). None of the study patients had pneumococcal pneumonia. The most common initial empirical therapy for both groups was third-generation cephalosporins (96.0% vs. 91.0%; P = 0.34) which was active against a significantly higher proportion of the cases than of the controls (97.8% vs. 78.7%; P = 0.003). Thirty-day mortality was significantly lower in the case group than in the control group (10.0% vs. 24.0%; P = 0.04).SPP was not associated with pneumococcal pneumonia and showed lower mortality than SBP caused by other organisms. However, the present study was constrained by the natural limitations characteristic of a small, retrospective study. Therefore, large-scale, well-controlled studies are required to demonstrate the influence of SPP on mortality, which was marginal in the present study.

Multiple myeloma in a patient with acromegaly

Acromegaly is a slowly progressing condition resulting from excess growth hormone (GH), generally caused by a GH-secreting pituitary adenoma. Cancer is the third most common cause of mortality in patients with acromegaly, and insulin-like growth factor 1 (IGF-1) is known to influence tumor formation by increasing cell proliferation and inhibiting apoptosis. Multiple myeloma (MM) is a plasma cell neoplasm, and previous studies have suggested the possible role of IGF-1 in its development of MM. However, no cases of acromegaly accompanied with MM have been reported in Asia to date. We here report the case of a 58-year-old woman with acromegaly accompanied with MM who presented with longstanding acromegalic manifestations resulting from a GH-secreting pituitary adenoma and also exhibited anemia, a reversed albumin/globulin ratio, and plasmacytosis on bone marrow examination. Because IGF-1 has been suggested to play an important role in the development and progression of MM, the patient promptly underwent surgical removal of the pituitary adenoma via a transsphenoidal approach. Since there is currently no consensus on therapeutic guidelines and suggested prognosis for MM with acromegaly, long-term follow-up of such cases is needed.

Invasive Pulmonary Aspergillosis-mimicking Tuberculosis

BACKGROUND

Pulmonary tuberculosis is occasionally confused with invasive pulmonary aspergillosis (IPA) in transplant recipients, since clinical suspicion and early diagnosis of pulmonary tuberculosis and IPA rely heavily on imaging modes such as computed tomography (CT). We therefore investigated IPA-mimicking tuberculosis in transplant recipients.

METHODS

All adult transplant recipients who developed tuberculosis or IPA at a tertiary hospital in an intermediate tuberculosis-burden country during a 6-year period were enrolled. First, we tested whether experienced radiologists could differentiate pulmonary tuberculosis from IPA. Second, we determined which radiologic findings could help us differentiate them.

RESULTS

During the study period, 28 transplant recipients developed pulmonary tuberculosis after transplantation, and 80 patients developed IPA after transplantation. Two experienced radiologists scored blindly 28 tuberculosis and 50 randomly selected IPA cases. The sensitivities of radiologists A and B for IPA were 78% and 68%, respectively (poor agreement, kappa value = 0.25). The sensitivities of radiologists A and B for tuberculosis were 64% and 61%, respectively (excellent agreement, kappa value = 0.77). We then compared the CT findings of the 28 patients with tuberculosis and 80 patients with IPA. Infarct-shaped consolidations and smooth bronchial wall thickening were more frequent in IPA, and mass-shaped consolidations and centrilobular nodules (<10 mm, clustered) were more frequent in tuberculosis.

CONCLUSIONS

Certain CT findings appear to be helpful in differentiating between IPA and tuberculosis. Nevertheless, the CT findings of about one-third of pulmonary tuberculosis cases in transplant recipients are very close to those of IPA.

Comparison of the clinical characteristics of Mycobacterium tuberculosis and nontuberculous mycobacteria patients with joint involvement

Nontuberculous mycobacteria (NTM) joint involvement is rare. However, the incidence of NTM disease is increasing and it is difficult to distinguish NTM from Mycobacterium tuberculosis (MTB). Here, the clinical characteristics of NTM joint involvement were compared with those of MTB. Distal joint involvement and precipitating factors were significantly more frequent for NTM joint infections. Because pathologic findings of NTM and MTB were similar, microbiological investigations are needed.

Clinical characteristics and survival of Korean idiopathic pulmonary arterial hypertension patients based on vasoreactivity

We aimed to identify a vasoreactive subset of patients with idiopathic pulmonary arterial hypertension (IPAH) in Korea and to show their clinical characteristics and prognosis. Data on patients who were diagnosed with IPAH at Asan Medical Center between January 1994 and March 2013 were retrospectively collected. Acute vasodilator testing was performed with inhaled nitric oxide during diagnostic right heart catheterization. A positive acute response was defined as a reduction in mean pulmonary arterial pressure (PAP) ≥10 mmHg to an absolute level of mean PAP <40 mmHg without a decrease in cardiac output. Among a total of 60 IPAH patients included for analysis, 9 (15%) showed a positive acute response to acute vasodilator testing. Acute responders showed significantly lower peak velocity of a tricuspid regurgitation jet on echocardiography (4.1±0.3 m/s vs. 4.6±0.6 m/s; P=0.01) and significantly lower mean PAP hemodynamically (47±10 mmHg vs. 63±17 mmHg; P=0.003) than non-responders at baseline. The survival rate of acute responders was 88% at 1, 3, 5, and 10 yr, respectively, which was significantly higher than that of non-responders (85%, 71%, 55%, and 40%, respectively; P=0.029). In conclusion, Korean IPAH patients with vasoreactivity showed better baseline hemodynamic features and survival than those without vasoreactivity.

A Case of IgG4-Related Lung Disease Presenting as Interstitial Lung Disease

Intrathoracic involvement of immunoglobulin G4 (IgG4)-related disease has recently been reported. However, a subset of the disease presenting as interstitial lung disease is rare. Here, we report a case of a 35-year-old man with IgG4-related lung disease with manifestations similar to those of interstitial lung disease. Chest computed tomography showed diffuse ground glass opacities and rapidly progressive pleural and subpleural fibrosis in both upper lobes. Histological findings showed diffuse interstitial lymphoplasmacytic infiltration with an increased number of IgG4-positive plasma cells. Serum levels of IgG and IgG4 were also increased. The patient was diagnosed with IgG4-related lung disease, treated with anti-inflammatory agents, and showed improvement. Lung involvement of IgG4-related disease can present as interstitial lung disease and, therefore, should be differentiated when evaluating interstitial lung disease.

Novel green synthetic strategy to prepare ZnO nanocrystals using rambutan (Nephelium lappaceum L.) peel extract and its antibacterial applications

In the present investigation, we report a sustainable novel green synthetic strategy to synthesis zinc oxide nanocrystals. This is the first report on sustainable biosynthesis of zinc oxide nanocrystals employing Nephelium lappaceum L., peel extract as a natural ligation agent. Green synthesis of zinc oxide nanocrystals was carried out via zinc-ellagate complex formation using rambutan peel wastes. The successful formation of zinc oxide nanocrystals was confirmed employing standard characterisation studies. A possible mechanism for the formation of ZnO nanocrystals with rambutan peel extract was also proposed. The prepared ZnO nanocrystals were coated on the cotton fabric and their antibacterial activity were analyzed. ZnO nanocrystals coated cotton showed good antibacterial activity towards Escherichia coli (E. coli), gram negative bacteria and Staphylococcus aureus (S. aureus), gram positive bacteria.

Ultrastructural observation of electron irradiation damage of lamellar bone

The ultrastructure of murine femoral lamellar bone and the effect of electron irradiation (200 kV) on collagen and mineral features were investigated using in situ high resolution transmission electron microscopy (HRTEM). Bands of collagen fibrils were mostly aligned parallel to the long axis of the bones, with some bands of fibrils inclined in longitudinal sections. The similarity of the ultrastructure between the longitudinal and transverse sections supports the rotated plywood structure of the lamellar bone. The collagen fibrils appeared damaged and the mineral crystals were coarsened after electron irradiation. Continuous diffraction rings became spotty and the contrast between rings and the background became sharper, further suggesting coarsening of apatite crystals and increased crystallinity after irradiation. No new phases were observed after irradiation. Both the damage to collagen and coarsening of apatite crystals can deteriorate the strength and integrity of bone, and may provide insight into fracture in patients who have undergone radiation therapy.

Enhanced wear and fatigue properties of Ti-6Al-4V alloy modified by plasma carburizing/CrN coating

In this study, a newly developed duplex coating method incorporating plasma carburization and CrN coating was applied to Ti-6Al-4V and its effects on the wear resistance and fatigue life were investigated. The carburized layer with approximately150 microm in depth and CrN coating film with 7.5 microm in thickness were formed after duplex coating. Hard carbide particles such as TiC And V(4)C(3) were formed in the carburized layer. XRD diffraction pattern analysis revealed that CrN film had predominant [111] and [200] textures. The hardness (Hv) was significantly improved up to about 1,960 after duplex coating while the hardness value of original Ti-6Al-4V was 402. The threshold load for the modification and/or failure of CrN coating was measured to be 32 N using the acoustic emission technique. The wear resistance and fatigue life of duplex-coated Ti-6Al-4V improved significantly compared to those of un-treated specimen. The enhanced wear resistance can be attributed to the excellent adhesion and improved hardness of CrN coating film for the duplex-coated Ti-6Al-4V. The initiation of fatigue cracks is likely to be retarded by the presence of hard and strong layers on the surface, resulting in the enhanced fatigue life.

Production of penicillic acid by Aspergillus sclerotiorum CGF

The production of penicillic acid by Aspergillus sclerotiorum CGF for the biocontrol of Phytophthora disease was investigated in submerged fermentation using media composed of different nutrients. Soluble starch was found to be the most effective substrate among the carbon sources used, and produced the highest penicillic acid concentration of 2.98 mg ml(-1). When organic nitrogen sources were used, pharmamedia, yeast extract, and polypeptone-S were found to be suitable organic nitrogen sources (2.46-2.71 mg ml(-1)). The production of penicillic acid was not detected in when inorganic nitrogen sources were used. Only Na2HPO4, among the metal ions and phosphate salts tested, increased the production of penicillic acid (approximately 20%). When A. sclerotiorum CGF was cultured in optimal medium [8.0% (w/v) soluble starch, 0.6% (w/v) yeast extract, and 0.3% (w/v) Na2HPO4], maximum penicillic acid concentration (approximately 9.40 mg ml(-1)) and cell mass (approximately 17.4 g l(-1)) were obtained after 12 days.

Production of cellulases and hemicellulases by Aspergillus niger KK2 from lignocellulosic biomass

To investigate the production of cellulases and hemicellulases from Aspergillus niger KK2, solid state fermentation (SSF) was performed by using different ratios of rice straw and wheat bran. When A. niger KK2 was grown on rice straw alone as a solid support in SSF, the maximum FPase activity was 19.5 IU g(-1) in 4 days. Also, CMCase (129 IU g(-1)), beta-glucosidase (100 IU g(-1)), xylanase (5070 IU g(-1)) and beta-xylosidase (193 IU g(-1)) activities were concurrently obtained after 5-6 days of fermentation. The higher enzyme activities produced by A. niger KK2 is a significant advantage from the viewpoint of practical saccharification reaction. Cellulases and hemicellulases produced by A. niger KK2 might be applied to pulp and paper industry, feed industry and chemical industry.

Independent Exponential Feeding of Glycerol and Methanol for Fed-Batch Culture of Recombinant Hansenula polymorpha DL-1

As a novel feeding strategy for optimizing human epidermal growth factor (hEGF) production with a recombinant Hansenula polymorpha DL-1 using the methanol oxidase (MOX) promoter in H. polymorpha DL-1, independent exponential feeding of two substrates was used. A simple kinetic model considering the cell growth on two substrates was established and used to calculate the respective feeding rates of glycerol and methanol. In the fedbatch culture with methanol-only feeding, the optimal set point of specific growth rate on methanol was found to be 0.10 h-1. When the fed-batch cultures were conducted by the independent feeding of glycerol and methanol, the actual specific growth rate on glycerol and methanol was slightly lower than the set point of specific growth rate. By the uncoupled feeding of glycerol and methanol the volumetric productivity of hEGF increased from 6.4 to 8.0 mg/(L.h), compared with methanol-only feeding.

Improvement for the production of clavulanic acid by mutant Streptomyces clavuligerus

AIMS

To improve the production of clavulanic acid through the development of strains, the selection of a production medium and a pH shift strategy in a bioreactor.

METHODS AND RESULTS

Streptomyces clavuligerus mutant 15 was selected by antibacterial activities. As a result of pH control in a 2.5 l bioreactor, the highest productivity (3.37 microg x ml(-1) x h(-1)) was obtained at a controlled pH of 7.0.

CONCLUSIONS

The highest level of production obtained was an increase of about 36% compared with a non-controlled pH. When the production of clavulanic acid reached the maximum level, the pH was shifted from 7.0 to 6.0 for reduction in decomposition rate. The maximum concentration of clavulanic acid was maintained for 24 h as a result of the pH shift control, and a significant reduction in the decomposition of clavulanic acid was obtained.

SIGNIFICANCE AND IMPACT OF THE STUDY

Clavulanic acid decomposition was considerably reduced as a result of the pH shift control. The results of this study can be applied for the efficient production of beta-lactamase inhibitory antibiotics.

Xylanase production in solid state fermentation by Aspergillus niger mutant using statistical experimental designs

The initial moisture content, cultivation time, inoculum size and concentration of basal medium were optimized in solid state fermentation (SSF) for the production of xylanase by an Aspergillus niger mutant using statistical experimental designs. The cultivation time and concentration of basal medium were the most important factors affecting xylanase activity. An inoculum size of 5 x 10(5) spores/g, initial moisture content of 65%, cultivation time of 5 days and 10 times concentration of basal medium containing 50 times concentration of corn steep liquor were optimum for xylanase production in SSF. Under the optimized conditions, the activity and productivity of xylanase obtained after 5 days of fermentation were 5,071 IU/g of rice straw and 14,790 IU l(-1) h(-1), respectively. The xylanase activity predicted by a polynomial model was 5,484 IU/g of rice straw.

Tumor necrosis factor-related apoptosis inducing ligand (TRAIL)-induced apoptosis is dependent on activation of cysteine and serine proteases

We examined the role of caspases and serine protease(s) in cell death induced by tumour necrosis factor-related apoptosis-inducing ligand (TRAIL). After incubation of adenocarcinoma cells with TRAIL, caspase-3, -8 were activated and the cleavage of Bid induced the release of cytochrome c, from the mitochondria to the cytosol. Tetrapeptide inhibitors of caspase-1, -2, -3, and -8 suppressed DNA fragmentation and attenuated the release of cytochrome c, whereas inhibitors of caspase-5 did not. Interestingly, the general serine protease(s) inhibitor 4-(2-aminoethyl)benzylsulfonyl fluoride (AEBSF) resulted in the arrest of apoptosis. However, the AEBSF did not prevent the release of mitochondrial cytochrome c during TRAIL-induced apoptosis. From these results, we postulate that serine protease(s) may be involved in post-mitochondrial apoptotic events, that lead to the activation of the initiator, caspase-9.

Protein kinase C activation by PMA rapidly induces apoptosis through caspase-3/CPP32 and serine protease(s) in a gastric cancer cell line

Phorbol 12-myristate 13-acetate (PMA) rapidly induced cell death in SNU-16 gastric adenocarcinoma cells. DNA ladder formation and caspase-3/CPP32 activation were observed in PMA treated cells indicating that PMA induces apoptosis. z-DEVD-fmk, specific inhibitor of caspase-3/CPP32, inhibited the induction of apoptosis by PMA, demonstrating that caspase/CPP32 are critically involved in PMA-induced apoptosis. The serine protein inhibitor 4-(2-aminoethyl)benzenesulfonyl fluoride effectively blocked apoptosis, and also prevented caspase-3/CPP32 activation. Go6983, a specific inhibitor of PKC, almost completely suppressed apoptosis and caspase-3/CPP32 activation. Furthermore, 1,2-dihexanoyl-sn-glycerol, an endogenous activator of PKC, induced apoptosis detected by DNA fragmentation and Hoechst 33258 nuclear staining. From these results, we conclude that PMA is not only a tumor promoter, but can also induce apoptosis in gastric cancer cells. PMA-induced apoptosis appears to be mediated through activation of protein kinase C, and the activation of serine protease(s) and caspase-3/CPP32 may be the molecular mechanisms by which PMA induces apoptosis.

Growth-inhibitory effect of adenovirus-mediated p53 gene transfer on medulloblastoma cell line, Daoy, harboring mutant p53

To improve the survival rate, gene therapy, such as the replacement of inactivated tumor suppressor genes, has become a new investigational adjuvant treatment modality for human malignancies. We investigated the effect of adenovirus(Ad)-mediated transfer of wildtype p53 tumor suppressor gene on the medulloblastoma cell line, Daoy, which harbors mutant-type p53 gene. At 50 multiplicity of infection (moi), immunohistochemical staining with p53 monoclonal antibody showed positive staining in all cells 2 days after Ad-CMV-p53 infection. The high expression of wild-type p53 protein was detected in Ad-CMV-p53-infected cells, and expression of wild-type p53 protein peaked on day 2 after the infection. The growth of Ad-CMV-p53-infected cells was greatly suppressed in vitro, and the Ad-CMV-p53 treatment significantly reduced the tumor mass in vivo. The mean weight of Ad-CMV- infected tumors was only 16% of those which were mock infected, and 25% of those which were Ad-CMV-beta-gal infected. On microscopic examination, Ad-CMV-p53-infected tumors showed numerous apoptotic bodies. This Ad-CMV-p53 gene transfer showed high transduction efficacy and expression, resulting in significant growth inhibition of Daoy harboring mutant type p53.

Growth inhibitory effect on glioma cells of adenovirus-mediated p16/INK4a gene transfer in vitro and in vivo

The tumour suppressor gene p16/INK4a encodes a specific inhibitor of the cyclin D-dependent kinases CDK4 and CDK6. p16/INK4a prevents the association of CDK4 with cyclin D1, and subsequently inhibits phosphorylation of retinoblastoma tumour suppressor protein (pRb), thus preventing exit from the G1 phase. In human cancers, the estimated frequency of genetic alteration involving the p16/INK4a locus is believed to be second only to alteration of p53. A high frequency (greater than 50%) of homozygous p16/INK4a gene deletion has been demonstrated in glioblastoma tissues and p16/INK4a is altered in 80% of glioma cell lines. Therefore, restoration of p16/INK4a would suppress cell proliferation and induce cell growth arrest. We showed here that restoration of p16/INK4a expression in p16 negative U87MG, U251MG and partially deleted U373MG by Ad-CMV-p16/INK4a induced growth suppression in vitro and in vivo. Expression of p16 transferred by Ad-CMV-p16/INK4a in glioma cells was highly efficient and maintained for more than seven days. In addition, we found that the endogenous status of p16 and Rb might affect the expression of exogenous p16/INK4a gene and inhibitory effect of cell proliferation. Even though, there were several factors affecting the efficiency of Ad-CMV-p16/INK4 gene transfer, our results suggest that Ad-CMV-p16 gene therapy strategy is potentially useful and warrants further clinical investigation for the treatment of gliomas.

Growth inhibitory effect on glioma cells of adenovirus-mediated p16/INK4a gene transfer in vitro and in vivo

The tumour suppressor gene p16/INK4a encodes a specific inhibitor of the cyclin D-dependent kinases CDK4 and CDK6. p16/INK4a prevents the association of CDK4 with cyclin D1, and subsequently inhibits phosphorylation of retinoblastoma tumour suppressor protein (pRb), thus preventing exit from the G1 phase. In human cancers, the estimated frequency of genetic alteration involving the p16/INK4a locus is believed to be second only to alteration of p53. A high frequency (greater than 50%) of homozygous p16/INK4a gene deletion has been demonstrated in glioblastoma tissues and p16/INK4a is altered in 80% of glioma cell lines. Therefore, restoration of p16/INK4a would suppress cell proliferation and induce cell growth arrest. We showed here that restoration of p16/INK4a expression in p16 negative U87MG, U251MG and partially deleted U373MG by Ad-CMV-p16/INK4a induced growth suppression in vitro and in vivo. Expression of p16 transferred by Ad-CMV-p16/INK4a in glioma cells was highly efficient and maintained for more than seven days. In addition, we found that the endogenous status of p16 and Rb might affect the expression of exogenous p16/INK4a gene and inhibitory effect of cell proliferation. Even though, there were several factors affecting the efficiency of Ad-CMV-p16/INK4 gene transfer, our results suggest that Ad-CMV-p16 gene therapy strategy is potentially useful and warrants further clinical investigation for the treatment of gliomas.