Investigation of the Effect of 3D Meniscus Geometry on Fluid Dynamics and Crystallization via In Situ Optical Microscopy-Assisted Mathematical Modeling.

Solution-based thin-film solidification is a complex process involving various transport phenomena that are intricately dependent on multiple experimental parameters. The difficulty of analyzing this process experimentally or conducting exact numerical simulation make it challenging to understand, predict, and control the solidification process. In this work, a simple and effective technique to analyze the thin-film solidification process during solution shearing, based on 3D geometrical model of the meniscus, is proposed. The 3D meniscus geometry, which changes depending on the experimental parameters, is attained using high-speed side-view and top-view in situ microscopy. Thereafter, mass and momentum transport mathematical models are applied to obtain numerical solutions of transport phenomena within the meniscus. Utilizing these results, the underlying mechanism of dendritic growth of small molecule organic semiconductor is elucidated, which has previously been unknown. The 3D meniscus modeling is particularly important for this analysis, as dendrite formation is strongly dependent on the meniscus geometry near the contact line and mass transport variation perpendicular to the coating direction. This technique enables the study of complex relationship between experimental parameters and solidification process, which is widely applicable to various materials and coating systems; whereby, better understanding of thin-film growth and device performance optimization is possible.

Korean Red Ginseng increases defective pol gene in peripheral blood mononuclear cells of HIV-1-infected patients; inhibition of its detection during ginseng-based combination therapy.

BACKGROUND: We have reported that defective nef and gag genes are induced in HIV-1-infected patients treated with Korean Red Ginseng (KRG). METHODS: To investigate whether KRG treatment and highly active antiretroviral therapy (HAART) affect genetic defects in the pol gene, we amplified and sequenced a partial pol gene (p-pol) containing the integrase portion (1.2 kb) by nested PCR with sequential peripheral blood mononuclear cells over 20 years and compared it with those patients at baseline, in control patients, those taking ginseng-based combination therapy (GCT; KRG plus combinational antiretroviral therapy) and HAART alone. We also compared our findings to look for the full-length pol gene (pol) (3.0-kb). RESULTS: Twenty-patients infected with subtype B were treated with KRG for 116 ± 58 months in the absence of HAART. Internal deletion in the pol gene (Δpol) was significantly higher in the KRG group (11.9%) than in the control group and at baseline; its detection was significantly inhibited during GCT as much as during HAART. In addition, the Δpol in p-pol significantly depended on the duration of KRG treatment. In pol, the proportion of Δpol was significantly higher in the KRG group (38.7%) than in the control group, and it was significantly inhibited during GCT and HAART. In contrast, the proportion of stop codon appeared not to be affected by KRG treatment. The PCR success rate was significantly decreased with longer GCT. CONCLUSION: The proportion of Δpol depends on template size as well as KRG treatment. HAART decreases the detection of Δpol.

Genetic defects in the nef gene are associated with Korean Red Ginseng intake: monitoring of nef sequence polymorphisms over 20 years.

BACKGROUND: The presence of gross deletions in the human immunodeficiency virus nef gene (gΔnef) is associated with long-term nonprogression of infected patients. Here, we investigated how quickly genetic defects in the nef gene are associated with Korean Red Ginseng (KRG) intake in 10 long-term slow progressors. METHODS: This study was divided into three phases over a 20-yr period; baseline, KRG intake alone, and KRG plus highly active antiretroviral therapy (ART). nef gene amplicons were obtained using reverse transcription polymerase chain reaction (PCR) and nested PCR from 10 long-term slow progressors (n = 1,396), and nested PCR from 36 control patients (n = 198), and 28 ART patients (n = 157), and these were then sequenced. The proportion of gΔnef, premature stop codons, and not in-frame insertion or deletion of a nucleotide was compared between three phases, control, and ART patients. RESULTS: The proportion of defective nef genes was significantly higher in on-KRG patients (15.6%) than in baseline (5.7%), control (5.6%), on-KRG plus ART phase (7.8%), and on-ART patients (6.6%; p < 0.01). Small in-frame deletions or insertions were significantly more frequent among patients treated with KRG alone compared with controls (p < 0.01). Significantly fewer instances of genetic defects were detected in samples taken during the KRG plus ART phase (7.8%; p < 0.01). The earliest defects detected were gΔnef and small in-frame deletions after 7 mo and 67 mo of KRG intake, respectively. CONCLUSION: KRG treatment might induce genetic defects in the nef gene. This report provides new insight into the importance of genetic defects in the pathogenesis of AIDS.

The first report of disseminated Nocardia concava infection, in an immunocompromised patient, in South Korea.

A new Nocardia species, N. concava, was first reported in Japan in 2005. To date, there have been only 3 case reports of N. concava infection worldwide (2 in Japan and 1 in China), and only 1 of these reports has detailed the clinical characteristics of N. concava, in China. Here we report the first case of disseminated infection caused by N. concava- in a patient with a history of glucocorticoid use-in South Korea. Species identification of N. concava was done with 16S rRNA sequencing and was confirmed by biochemical tests using urea, xanthine, tyrosine, and hypoxanthine decomposition. The patient was successfully treated with trimethoprim-sulfamethoxazole.

Risk factors and outcome for breakthrough candidaemia in patients with cancer.

While candidaemia that develops during systemic antifungal prophylaxis or therapy [breakthrough (BT) candidaemia] has been reported increasingly, the risk factors and outcome of BT candidaemia are not yet known definitely. We evaluated a consecutive series of cancer patients with candidaemia at Asan Medical Center during 6 years to identify risk factors and outcome in BT candidaemia comparing with non-BT candidaemia. Fifty-four episodes of candidaemia in cancer patients diagnosed during this period were reviewed retrospectively. There were 10 episodes (18.5%) of BT candidaemia in which the species distribution and frequency of catheter-related infection in the BT and non-BT groups were similar. BT candidaemia had a tendency to occur more frequently in patients with haematological than non-haematological diseases. Profound neutropenia and disseminated candidiasis were more common in the BT group; however, these differences were not statistically significant (P = 0.17 and 0.07 respectively). The duration of prior antibiotic therapy and duration of profound neutropenia (<100 mm(-3)) were identified as risk factors for BT candidaemia (P < 0.01 and 0.02 respectively) in univariate analysis and the latter was the only risk factor in multivariate analysis. The death rates due to candidaemia were 85.7% in the BT group and 42.9% in the non-BT group (P = 0.08); however, BT candidaemia alone did not increase mortality rate.

Risk factors for the acquisition of carbapenem-resistant Klebsiella pneumoniae among hospitalized patients.

The isolation of carbapenem-resistant Klebsiella pneumoniae (CRKP) has been increasingly reported. However, no study analyzing potential risk factors for the acquisition of CRKP has been published as of now. We therefore performed a case-control study to determine the risk factors for the acquisition of CRKP. CRKP was nosocomially isolated from 30 patients between January 1997 and August 2003. Control patients were randomly selected at a ratio of 4:1 from the same medical or surgical services from which patients were receiving care when isolation of CRKP occurred. Risk factors for CRKP were previous use of carbapenem (adjusted odds ratio [AOR], 28.68; 95% confidence interval [CI], 9.08-90.55) and cephalosporin (AOR, 4.10; 95% CI, 1.35-12.43). In contrast, previous use of fluoroquinolone was negatively associated with isolation of CRKP (AOR, 0.26; 95% CI 0.07-0.97); however, the possibility of selection bias cannot be ruled out. Our results suggest that the nosocomial isolation of CRKP is strongly favored by the selection pressure of carbapenem.

Risk factors for acquisition of imipenem-resistant Acinetobacter baumannii: a case-control study.

Risk factors for the nosocomial occurrence of imipenem-resistant Acinetobacter baumannii (IRAB) were determined. A case-control study design was used for a comparison of two groups of A. baumannii-positive patients with control patients. Nosocomial IRAB was isolated from the first group of A. baumannii-positive patients, and imipenem-susceptible A. baumannii (ISAB) was isolated from the second group. The control patients were randomly selected in a 4:1 ratio from the same medical or surgical services from which the A. baumannii-positive patients were receiving care when the isolation of IRAB occurred. Risk factors analyzed included demographic variables, comorbid conditions, variables related to hospitalization, and the antimicrobials used. IRAB was isolated from 104 patients, and ISAB was isolated from 387 patients between January and December 2000. The risk factors for IRAB were a previous intensive care unit (ICU) stay (odds ratio [OR], 21.54; 95% confidence interval [CI], 10.73 to 43.23) and prior exposure to imipenem (OR, 9.18; 95% CI, 3.99 to 21.13) or third-generation cephalosporins (OR, 2.11; 95% CI, 1.13 to 3.95). Risk factors for ISAB were a previous ICU stay (OR, 8.05; 95% CI, 5.67 to 11.44) and exposure to third-generation cephalosporins (OR, 2.07; 95% CI, 1.47 to 2.91). Our results suggest that the nosocomial occurrence of IRAB or ISAB is strongly related to an ICU stay, and IRAB occurrence may be favored by the selection pressure of imipenem.

Outcome of antibiotic therapy for third-generation cephalosporin-resistant Gram-negative bacteraemia: an analysis of 249 cases caused by Citrobacter, Enterobacter and Serratia species.

Two hundred and forty-nine patients with monomicrobial bacteraemia due to third-generation cephalosporin (TGC)-resistant Citrobacter freundii (42), E. aerogenes (23), E. cloacae (143), and Serratia marcescens (41) were analyzed for antibiotic therapy used and outcome. For isolates with resistance to any of the TGCs, all beta-lactams, except imipenem, were considered ineffective. Of 152 patients given appropriate treatment, the mortality rates were 10.9% for 128 patients given monotherapy and 25.0% for 24 patients given combination therapy (P=0.09). Of patients given monotherapy, there were no significant differences in mortality between imipenem, aminoglycoside, and ciprofloxacin treatment groups (P=0.57). Only shock was associated with mortality in multivariate analysis. In conclusion, for patients with TGC-resistant Gram-negative bacteraemia, no significant difference in outcome was observed between single antibiotic therapy groups or monotherapy and combination therapy groups.

Bacteraemia due to tribe Proteeae: a review of 132 cases during a decade (1991-2000).

To characterize the clinical features of bacteraemia due to tribe Proteeae, 132 cases among 130 patients from 1991 to 2000 were analysed. The organisms included the Proteus species in 63 cases (P. mirabilis in 41, P. penneri in 2 and P. vulgaris in 20), the Providencia species in 8 (P. rettgeri in 3 and P. stuartii 5) and Morganella morganii in 61. Morganella bacteraemia occurred more frequently in the hospital (70.5%). Biliary and hepatic diseases were predominant in cases with Morganella bacteraemia while cardiovascular, urological and neurological diseases were more common in cases with Proteus bacteraemia. Biliary drainage catheters had more frequently been placed in cases with Morganella bacteraemia (39.3%, p < 0.001), and urinary catheters more frequently in cases with Proteus bacteraemia (17.5%). Biliary infection was most common in cases with Morganella bacteraemia (49.2%), while urinary tract infection (UTI) was most common in cases with Proteus bacteraemia (47.6%). Mortality directly related to bacteraemia due to tribe Proteeae was 20.8% (22.6, 50.0 and 15.0% for Proteus, Providencia and Morganella bacteraemia, respectively). In conclusion, Morganella bacteraemia was most frequently associated with biliary infection, while Proteus bacteraemia was most frequently with UTI. Providencia bacteraemia was relatively uncommon and it can be associated with infections other than UTI.

Meningococcal disease in the republic of Korea army: incidence and serogroups determined by PCR.

This study was performed to determine the incidence and serogroups of meningococcal disease in the Korean Army. From August 2000 to July 2001, we identified prospective cases in the Korean Army. Meningococcal disease was confirmed by isolation of Neisseria meningitidis or detection of its antigen by latex agglutination from cerebrospinal fluid (CSF) or blood. Polymerase chain reactions (PCRs) were performed in the crgA gene to identify N. meningitidis regardless of its serogroup, and then in orf-2 (serogroup A) and siaD (serogroups B, C, Y, and W135) respectively for serogroup prediction. During the study period, twelve patients (four meningitis and eight septicaemia) were identified. The annual incidence was 2.2 per 100,000 (95% confidence interval, 1.3-3.8) among 550,000 private soldiers. Latex agglutinations were positive to A/C/Y/W135 polyvalent latex, but not to B latex in all patients. PCRs of crgA gene were positive in ten patients, whose samples (2 isolates from CSF, 2 CSFs, and 6 sera) were stored. In PCRs for serogroup prediction, one isolate was serogroup A, and one isolate and two sera were serogroup C. The need for meningococcal vaccination would be considered in the Korean Army through the cost-benefit analysis based on the result of this study.

The possible role of cerebrospinal fluid adenosine deaminase activity in the diagnosis of tuberculous meningitis in adults.

We studied an adenosine deaminase (ADA) activity in the cerebrospinal fluid (CSF) of 182 patients with meningitis. The patients were subdivided into four groups, (1) 36 cases of tuberculous meningitis; (2) 130 cases of viral or aseptic meningitis; (3) nine cases of bacterial meningitis; (4) seven cases of cryptococcal meningitis. Mean+/-S.D. ADA activity was 12.76+/-7.53 U/l in group 1; 2.58+/-2.37 U/l in group 2; 7.38+/-3.27 U/l in group 3; 7.42+/-4.38 U/l in group 4. Comparing the ADA activity in each group with the other groups, the difference is significant (P<0.001), except between groups 3 and 4. The sensitivity of the test for group 1 compared with group 2 was 0.83 and the specificity was 0.95 when a cut-off value of 7 U/l was used. When group 1 was compared with groups 3 and 4, the sensitivity was 0.58 and the specificity was 0.89 and 0.71 with groups 3 and 4, respectively, when a cut-off value of 10 U/l was used. Values >15 U/l were not observed in any of the non-tuberculous meningitis patients; therefore, ADA activity >15 U/l could be a strong indication of tuberculous meningitis. We conclude that a determination of CSF ADA can aid in the early differential diagnosis of tuberculous meningitis.