Enhanced microbial safety of channel catfish (Ictalurus punctatus) fillet using recently invented medium molecular weight water-soluble chitosan coating.

Chitosan with higher molecular weight exhibited higher antimicrobial efficacy against foodborne pathogens. However, the poor water solubility of higher or medium molecular weight chitosan limits its applications. To overcome the challenge, our research team searched for simple preparation procedure for fast-dissolving medium molecular weight chitosan in water. Throughout the process, we were able to obtain a higher concentration of medium molecular weight water-soluble (MMWWS) chitosan (400 kDa). The MMWWS chitosan showed physicochemical properties that are suitable for edible coating. Antibacterial activities of 400-kDa chitosan coating prepared in acetic acid (1% v/v) or aspartic acid (1% or 3% w/v) were examined. The surface of catfish cubes was inoculated with six foodborne pathogens and then coated with chitosan solutions. The survival of each pathogen was evaluated during shelf life storage. Compared with the control, 3% w/v chitosan coating in aspartic acid solution exhibited the most effective antibacterial activities among other coating treatments, completely inhibiting Vibrio parahaemolyticus on the surface of catfish. The study suggested that chitosan dissolved in aspartic acid has the potential for use as an alternative antimicrobial coating for catfish fillet.

Short communication: Influence of an aqueous myrrh suspension on yogurt culture bacteria over yogurt shelf life.

Myrrh is an essential oil and natural flavoring approved by the US Food and Drug Administration, and it has antibacterial and antifungal activity against pathogens. Our objective was to determine the effect of an aqueous myrrh suspension on Streptococcus thermophilus and Lactobacillus delbrueckii ssp. bulgaricus counts in peptone solution and yogurt, as well as pH and titratable acidity of yogurt during 5 wk of storage at 1 to 4°C. The myrrh suspension (10% wt/vol) was prepared and incorporated into a pure culture dilution in peptone and into yogurt mix at a 1% (vol/vol) level. A control with no myrrh was also prepared, and 3 replications were conducted. Streptococcus thermophilus were enumerated using Streptococcus thermophilus agar with aerobic incubation at 37°C for 24 h, and Lactobacillus delbrueckii ssp. bulgaricus were enumerated using de Man, Rogosa, and Sharpe agar adjusted to pH 5.2, with anaerobic incubation at 43°C for 72 h. During the 8-h period after inoculation, S. thermophilus and L. delbrueckii ssp. bulgaricus counts in peptone solution at 37°C and 43°C, respectively, were not significantly different in the presence or absence of the aqueous myrrh suspension. Counts of S. thermophilus in yogurt containing myrrh (mean ± SD; 4.96 ± 0.58 log cfu/mL) were not significantly different from those in the control yogurt (4.87 ± 0.39 log cfu/mL). The log counts for L. delbrueckii ssp. bulgaricus in yogurt containing myrrh (5.04 ± 1.44 log cfu/mL) and those of the control (5.52 ± 1.81 log cfu/mL) did not differ, and the counts remained within 1 log of each other throughout 5 wk of storage. The pH of the yogurts containing the aqueous myrrh suspension was not significantly different from that of the control yogurts, and their pH values were within 0.1 pH unit of each other in any given week. Titratable acidity values remained steady around 1.1 to 1.2% lactic acid for both yogurt types throughout the storage period, with no significant differences between them. Yogurt culture bacteria can survive in the presence of a myrrh suspension in yogurt with no significant change in pH or titratable acidity. Therefore, it may be beneficial to add an aqueous myrrh suspension to yogurt.

Immunomagnetic separation of Vibrio vulnificus with antiflagellar monoclonal antibody.

Raw oysters are primary vectors for Vibrio vulnificus infections, and a rapid detection method for V. vulnificus in raw oysters before distribution would be an indispensable tool for the seafood industry. One approach to improving the recovery and detection of V. vulnificus without sacrificing assay time is through the use of immunomagnetic separation (IMS). The aim of this study was to develop and optimize an IMS protocol using anti-H (antiflagellar) antibody for determining the level of V. vulnificus in phosphate-buffered saline (PBS) suspensions and spiked oyster homogenate. Six monoclonal antibodies were produced by immunizing mice at 2-week intervals by injection of 50 microg of purified V. vulnificus ATCC 27562 flagellin. Antibodies that exhibited high anti-H titers were coated onto Cowan I Staphylococcus aureus cells and sheep anti-mouse immunoglobulin G immunomagnetic beads. The two reagents were used to determine the species specificity of the selected antibodies, which positively identified and coagglutinated 70 isolates identified genetically as V. vulnificus and did not react with 40 Vibrio parahaemolyticus isolates or nine other Vibrio species. The IMS protocol was optimized for PBS and oyster homogenate spiked with three different strains of V. vulnificus. IMS with V. vulnificus-spiked PBS yielded binding of 19 to 57%, and IMS with spiked oyster homogenate carried out at two V. vulnificus levels exhibited binding of 25 to 57%. The IMS protocol for V. vulnificus could be used to concentrate and detect V. vulnificus in seawater and shellfish homogenate.

Environmental monitoring and exposure science dataset to calculate ingestion and inhalation of metal(loid)s through preschool gardening.

Metal(loid) contamination may pose an increased risk of exposure to children residing near legacy and active resource extraction sites. Children may be exposed to arsenic, cadmium, and/or lead by ingestion and/or inhalation while engaging in school or home outdoor activities via environmental media including water, soil, dust, and locally grown produce. It is thus critical to collect site-specific data to best assess these risks. This data article provides gastric and lung in-vitro bioaccessibility assay (IVBA) data, as well as environmental monitoring data for water, soil, dust, and garden produce collected from preschools (N = 4) in mining communities throughout Nevada County, California in 2018. Arsenic, cadmium, and lead concentrations in the aforementioned media and synthetic gastric and lung fluids were measured by inductively coupled plasma-mass spectrometry (ICP-MS). This dataset provides useful metal(loid) concentrations for future risk assessments for similar settings.

Ingestion and inhalation of metal(loid)s through preschool gardening: An exposure and risk assessment in legacy mining communities.

Children residing in mining towns are potentially disproportionately exposed to metal(loid)s via ingestion and dust inhalation, thus, increasing their exposure when engaging in school or home gardening or playing outside. This citizen science study assessed preschool children's potential arsenic (As), cadmium (Cd), and lead (Pb) exposure via locally grown produce, water, incidental soil ingestion, and dust inhalation at four sites. Participants were trained to properly collect water, soil, and vegetable samples from their preschools in Nevada County, California. As, Cd, and Pb concentrations in irrigation sources did not exceed the U.S. EPA's maximum contaminant and action levels. In general, garden and playground As and Pb soil concentrations exceeded the U.S. EPA Regional Screening Level, CalEPA Human Health Screening Level, and California Department of Toxic Substances Control Screening Level. In contrast, all Cd concentrations were below these recommended screening levels. Dust samples (<10 µm diameter) were generated from surface garden and playground soil collected at the preschools by a technique that simulated windblown dust. Soil and dust samples were then analyzed by in-vitro bioaccessibility assays using synthetic lung and gastric fluids to estimate the bioaccessible fraction of As, Cd, and Pb in the body. Metal(loid) exposure via grown produce revealed that lettuce, carrot, and cabbage grown in the preschool gardens accumulated a higher concentration of metal(loid) than those store-bought nation-wide. None of the vegetables exceeded the respective recommendation maximum levels for Cd and Pb set by the World Health Organization Codex Alimentarius Commission. The results of this study indicate that consumption of preschool-grown produce and incidental soil ingestion were major contributors to preschool-aged children's exposure to As, Cd, and Pb. Traditionally, this level of site- and age-specific assessment and analyses does not occur at contaminated sites. The results of this holistic risk assessment can inform future risk assessment and public health interventions related to childhood metal(loid) exposures.

Heavy Metals in California Women Living in a Gold Mining-Impacted Community.

Gold mining activities occurred throughout the foothills of the Sierra Nevada Mountains in California, leaving behind persistent toxic contaminants in the soil, dust, and water that include arsenic and cadmium. Despite a high level of concern among local residents about potential exposure and high breast cancer rates, no biomonitoring data has been collected to evaluate the levels of heavy metals. We conducted a study to characterize the urinary levels of heavy metals among women in this region by working with the community in Nevada County. Sixty women provided urine samples and completed a questionnaire. We examined levels of arsenic, cadmium, and other metals in relation to the length of residency in the area, age, dietary factors, recreational activities, and smoking. We compared urinary metal levels in participants to levels in the United States National Health and Nutrition Examination Survey (NHANES). Overall, study participants had higher urinary levels of arsenic than women in the national sample. Cadmium levels were similar to the national average, although they were elevated in women ≥35 years who had lived in the region for 10 years or more. Arsenic levels were higher among women who smoked, ate fish, ate home-grown produce, and who reported frequent hiking or trail running, although these differences were not statistically significant. This study established a successful community-research partnership, which facilitated community dialogue about possible human health consequences of living in a mining-impacted area.

Impact of Euro-American sublineages of Mycobacterium tuberculosis on new infections among named contacts.

BACKGROUND: The impact of demographic, clinical, and bacterial factors on new infection by Euro-American lineage Mycobacterium tuberculosis among contacts of patients with tuberculosis (TB) has not been evaluated. OBJECTIVE: To describe the risk factors for new infection by Euro-American M. tuberculosis sublineages in San Francisco, California. DESIGN: We included contacts of patients with TB due to Euro-American M. tuberculosis. Sublineages were determined by large-sequence polymorphisms. We used tuberculin skin testing or QuantiFERON®-TB Gold In-Tube to identify contacts with new infection. Regression models with generalized estimating equations were used to determine the risk factors for new infection. RESULTS: We included 1488 contacts from 134 patients with TB. There were 79 (5.3%) contacts with new infection. In adjusted analyses, contacts of patients with TB due to region of difference 219 M. tuberculosis sublineage were less likely to have new infection (OR 0.23, 95%CI 0.06-0.84) than those with other sublineages. Other risk factors for new infection were contacts exposed to more than one patient with TB, contacts exposed for 30 days, or contacts with a history of smoking or excessive alcohol consumption. CONCLUSIONS: In addition to well-known exposure and clinical characteristics, bacterial characteristics independently contribute to the transmissibility of TB in San Francisco.

Clinical and bacteriological characteristics associated with clustering of multidrug-resistant tuberculosis.

SETTING: The impact of the genetic characteristics of Mycobacterium tuberculosis on the clustering of multidrug-resistant tuberculosis (MDR-TB) has not been analyzed together with clinical and demographic characteristics. OBJECTIVE: To determine factors associated with genotypic clustering of MDR-TB in a community-based study. DESIGN: We measured the proportion of clustered cases among MDR-TB patients and determined the impact of clinical and demographic characteristics and that of three M. tuberculosis genetic characteristics: lineage, drug resistance-associated mutations, and rpoA and rpoC compensatory mutations. RESULTS: Of 174 patients from California and Texas included in the study, the number infected by East-Asian, Euro-American, Indo-Oceanic and East-African-Indian M. tuberculosis lineages were respectively 70 (40.2%), 69 (39.7%), 33 (19.0%) and 2 (1.1%). The most common mutations associated with isoniazid and rifampin resistance were respectively katG S315T and rpoB S531L. Potential compensatory mutations in rpoA and rpoC were found in 35 isolates (20.1%). Hispanic ethnicity (OR 26.50, 95%CI 3.73-386.80), infection with an East-Asian M. tuberculosis lineage (OR 30.00, 95%CI 4.20-462.40) and rpoB mutation S531L (OR 4.03, 95%CI 1.05-23.10) were independent factors associated with genotypic clustering. CONCLUSION: Among the bacterial factors studied, East-Asian lineage and rpoB S531L mutation were independently associated with genotypic clustering, suggesting that bacterial factors have an impact on the ability of M. tuberculosis to cause secondary cases.

Viral levels in newborn African infants undergoing primary HIV-1 infection.

We examined weekly changes in viral levels in seven untreated infants infected with HIV at birth. Viral levels spiked immediately but reverted quickly to plateau levels typical of infant HIV infection within 2 weeks of first detected viraemia. We speculated that the depletion of naive, susceptible cells is responsible for the rapid decrease in spike levels and that the rapid replacement of lymphocytes in infants causes the high plateau viral levels (10(5) copies/ml) to be sustained.

Quantification of HIV-1 RNA in Dried Plasma Spots (DPS) : A Field Approach to Therapeutic Monitoring.

The ability to accurately measure viral RNA in the plasma (1-3) and intracellular (4-7) compartments of HIV-1-infected persons has led to a dramatic improvement in the understanding of the natural history of HIV-1 and AIDS. A number of recent studies have convincingly demonstrated that high levels of viral replication occur at all stages of disease (8-10), and that changes in viral RNA load are predictive of disease outcome (11,12), and response to therapy (13,14). These findings, combined with the introduction of potent new antivirals (15,16), have stimulated a growing interest in viral load monitoring, both as a function of disease status, and as a predictor of disease progression and therapeutic efficacy.

Identification and characterization of two bacteriocin-producing bacteria isolated from garlic and ginger root.

Two bacteriocin-producing bacterial strains were isolated from garlic and ginger root by the agar overlay method. The bacteria were identified by 16S rRNA sequence analyses and fermentation patterns as Leuconostoc mesenteroides (garlic isolate) and Lactococcus lactis (ginger isolate). The bacteriocins were assigned the names leucocin BC2 and lactocin GI3, respectively. Physiochemical properties and antimicrobial spectra of the bacteriocins were determined by the spot-on-lawn method. Both bacteriocins were inhibited by proteolytic enzymes. Leucocin BC2 exhibited a narrow antimicrobial spectrum, inhibiting only Bacillus, Enterococcus, and Listeria species. Lactocin GI3 had a broader spectrum, inhibiting Bacillus, Clostridium, Listeria, Enterococcus, Leuconostoc, Pediococcus, and Staphylococcus species. Both bacteriocins remained active when heated at 90 degrees C for 15 min or 120 degrees C for 20 min. Leucocin BC2 assayed at 37 degrees C showed an inhibitory activity of 1,600 AU/ml, whereas at 8 degrees C the activity was 12,800 AU/ml. Conversely, lactocin GI3 activity was the same at both assay temperatures. Both bacteriocins remained active over a pH range of 2.0 to 9.0 and in various organic solvents. The activity of leucocin BC2 was increased when treated with 0.5% acetic acid and 0.5% lactic acid, whereas lactocin GI3 activity was decreased with either acid. The molecular mass values were 3.7 kDa for leucocin BC2 and 3.9 kDa for lactocin GI3. These results show that the inhibitory substances produced by the bacteria isolated from garlic and ginger are bacteriocins that appear to be different in some characteristics from previously reported bacteriocins.

Inactivation of pathogenic bacteria by cucumber volatiles (E,Z)-2,6-nonadienal and (E)-2-nonenal.

The effects of (E,Z)-2,6-nonadienal (NDE) and (E)-2-nonenal (NE) on Bacillus cereus, Escherichia coli O157:H7, Listeria monocytogenes, and Salmonella Typhimurium were investigated. A suspension of each organism of 6 to 9 log CFU/ml was incubated for 1 h at 37 degrees C in brain heart infusion solution that contained 0 to 500 or 1,000 ppm of NDE or NE. Depending on concentration, exposure to either NDE or NE caused a reduction in CFU of each organism. Treatment with 250 and 500 ppm NDE completely eliminated viable B. cereus and Salmonella Typhimurium cells, respectively. L. monocytogenes was the most resistant to NDE, showing only about a 2-log reduction from exposure to 500 ppm for 1 h. Conversely, this concentration of NDE caused a 5.8-log reduction in E. coli O157:H7 cells. NE was also effective in inactivating organisms listed above. A higher concentration of NE, 1,000 ppm, was required to kill E. coli O157:H7, L. monocytogenes, or Salmonella Typhimurium compared with NDE. In conclusion, both NDE and NE demonstrated an apparent bactericidal activity against these pathogens.

Survival differences of Escherichia coli O157:H7 strains in apples of three varieties stored at various temperatures.

Differences in survival and growth among five different Escherichia coli O157:H7 strains in three apple varieties were determined at various temperatures. Jonathan, Golden Delicious, and Red Delicious apples were wounded and inoculated with E coli O157:H7 strains C7929 (apple cider isolate), 301C (chicken isolate), 204P (pork isolate), 933 (beef isolate), and 43890 (human isolate) at an initial level of 6 to 7 log CFU/g. The inoculated apples were stored at a constant temperature of 37, 25, 8, or 4 degrees C or at 37 degrees C for 24 h and then at 4 degrees C, and bacterial counts were determined every week for 28 days. By day 28, for Jonathan apples at 25 degrees C, the apple isolate counts were significantly higher than the chicken and human isolate counts. At 4 degrees C for 28 days, the human isolate inoculated into Jonathan, Golden Delicious, and Red Delicious apples was present in significantly smaller numbers than the other strains. The apple isolate survived significantly better at 4 degrees C, yielding the highest number of viable cells. By days 21 and 28, for apples stored at 37 degrees C for the first 24 h and then at 4 degrees C, the counts of viable E. coli O157:H7 apple and human isolates were 6.8 and 5.8 log CFU/g at the site of the wound, whereas for apples kept at 4 degrees C for the duration of storage, the respective counts were 5.6 and 1.5 log CFU/g. Our study shows that E. coli O157:H7 strains responded differentially to their ability to survive in these three apple varieties at 25 or 4 degrees C and produced higher viable counts when apples were temperature abused at 37 degrees C for 24 h and then stored at 4 degrees C for 27 days.

The leukocyte response of Japanese quail to Rous sarcoma virus-induced tumors.

In male Japanese quail, different circulating leukocyte responses were observed for progressors (birds developing a massive tumor that persisted throughout the experiment) and regressors (birds developing a tumor that gradually disappeared) after initial challenge with Rous sarcoma virus (RSV). Blood was sampled before and at weekly intervals postinoculation. Blood smears were prepared and stained with Diff Quik, and a light microscope (1000 x) was used in a direct count of 50 fields. Leukocytes were classified as heterophils, lymphocytes, monocytes, or eosinophils. The significant increase (P < 0.05) in total leukocytes at 14 days in regressors and progressors was consistent with the increase in tumor growth. The regressors' individual percentage of leukocytes did not deviate from control values, whereas the progressors' percentages of heterophils and monocytes were significantly higher (P < 0.05) and of lymphocytes significantly lower (P < 0.05) than those of controls by 14 days postinoculation. Indicative of this was the progressors' heterophil to lymphocyte ratio, which was significantly higher (P < 0.05) than that of controls 14 days post RSV challenge and remained elevated throughout the experiment. These findings suggest that the progressors' immune response is suppressed by proliferation of malignant cells. Therefore, the heterophil to lymphocyte ratio may be used in addition to tumor size to identify those birds that will regress RSV-induced tumors.

A randomized trial comparing peripherally inserted central venous catheters and peripheral intravenous catheters in infants with very low birth weight.

BACKGROUND/PURPOSE: To determine whether percutaneously inserted central venous catheters (PICC) and peripheral intravenous catheters (PIV) in infants with very low birth weight (VLBW) differ with respect to (1) incidence of sepsis, (2) number of insertion attempts and catheters required for total intravenous therapy, (3) courses of antibiotics, and (4) total duration of intravenous (IV) use. METHODS: A randomized comparative trial was conducted involving 63 VLBW infants (<1,251 g) who required IV therapy. Infants were assigned randomly at 1 week of age to either a PIV or a PICC catheter and followed up prospectively until an IV was no longer required or the infant was transferred out of the neonatal intensive care unit. RESULTS: Data were analyzed on an intention-to-treat basis. There was no difference in the incidence of sepsis (P = .64), number of courses of antibiotics (P = .16), or total duration of IV use (P= .34) between the 2 groups. The number of insertion attempts required for total IV therapy was significantly lower in the PICC group than in the PIV group (P = .008). There also was a significantly lower number of total catheters utilized in the PICC group (P = .002). When data were controlled for birth weight strata the results were similar. CONCLUSION: PICC lines reduced the number of painful IV procedures in VLBW infants without additional morbidity.

Efficacy of the investigational mTOR kinase inhibitor MLN0128/INK128 in models of B-cell acute lymphoblastic leukemia.

The mechanistic target of rapamycin (mTOR) is a serine/threonine kinase whose activity contributes to leukemia proliferation and survival. Compounds targeting the mTOR active site inhibit rapamycin-resistant functions and have enhanced anticancer activity in mouse models. MLN0128 (formerly known as INK128) is a novel, orally active mTOR kinase inhibitor currently in clinical development. Here, we evaluated MLN0128 in preclinical models of B-cell acute lymphoblastic leukemia (B-ALL). MLN0128 suppressed proliferation of B-ALL cell lines in vitro and reduced colony formation by primary human leukemia cells from adult and pediatric B-ALL patients. MLN0128 also boosted the efficacy of dasatinib (DA) in Philadelphia Chromosome-positive (Ph+) specimens. In a syngeneic mouse model of lymphoid BCR-ABL+ disease, daily oral dosing of MLN0128 rapidly cleared leukemic outgrowth. In primary xenografts of Ph+ B-ALL specimens, MLN0128 significantly enhanced the efficacy of DA. In non-Ph B-ALL xenografts, single agent MLN0128 had a cytostatic effect that was most pronounced in mice with low disease burden. In all in vivo models, MLN0128 was well tolerated and did not suppress endogenous bone marrow proliferation. These findings support the rationale for clinical testing of MLN0128 in both adult and pediatric B-ALL and provide insight towards optimizing therapeutic efficacy of mTOR kinase inhibitors.

A previously unrecognized promoter of LMO2 forms part of a transcriptional regulatory circuit mediating LMO2 expression in a subset of T-acute lymphoblastic leukaemia patients.

The T-cell oncogene Lim-only 2 (LMO2) critically influences both normal and malignant haematopoiesis. LMO2 is not normally expressed in T cells, yet ectopic expression is seen in the majority of T-acute lymphoblastic leukaemia (T-ALL) patients with specific translocations involving LMO2 in only a subset of these patients. Ectopic lmo2 expression in thymocytes of transgenic mice causes T-ALL, and retroviral vector integration into the LMO2 locus was implicated in the development of clonal T-cell disease in patients undergoing gene therapy. Using array-based chromatin immunoprecipitation, we now demonstrate that in contrast to B-acute lymphoblastic leukaemia, human T-ALL samples largely use promoter elements with little influence from distal enhancers. Active LMO2 promoter elements in T-ALL included a previously unrecognized third promoter, which we demonstrate to be active in cell lines, primary T-ALL patients and transgenic mice. The ETS factors ERG and FLI1 previously implicated in lmo2-dependent mouse models of T-ALL bind to the novel LMO2 promoter in human T-ALL samples, while in return LMO2 binds to blood stem/progenitor enhancers in the FLI1 and ERG gene loci. Moreover, LMO2, ERG and FLI1 all regulate the +1 enhancer of HHEX/PRH, which was recently implicated as a key mediator of early progenitor expansion in LMO2-driven T-ALL. Our data therefore suggest that a self-sustaining triad of LMO2/ERG/FLI1 stabilizes the expression of important mediators of the leukaemic phenotype such as HHEX/PRH.