High particle counts in neonatal parenteral nutrition solutions with added cysteine: Relationship to crystal formation and effect of filtration on cysteine content.

BACKGROUND: Parenteral nutrition(PN) solutions containing calcium gluconate and cysteine have elevated particle counts when analyzed using laser light obscuration (LO) as recommended by the United States Pharmacopeia. It is unclear whether increased particle formation in these solutions results in decreased availability of cysteine to neonatal patients due to filtration. OBJECTIVE: The purpose of this study was to measure cysteine concentrations in neonatal PN solutions before and after filtration as well as analyze precipitates on filters. METHODS: Solutions of PN containing amino acids with and without cysteine that were compounded with calcium chloride or calcium gluconate plus potassium phosphate were analyzed using LO. Concentrations of cysteine were measured before and after filtration. The effect on particle formation of magnesium sulfate (MgSO4 ) and D70 was also evaluated. RESULTS: Multiple additives including the specific calcium or D70 additive, cysteine, and MgSO4 influenced particle formation of particles detected using LO. There was no significant decrease in cysteine concentration because of filtering and there was no difference in the amount of calcium on filters of various solutions after filtration regardless of LO particle counts. Scanning electron micrographic (SEM) analysis found no significant differences in crystal composition. Light microscopic and SEM examination did not show evidence of high particle counts on filters. CONCLUSION: The increased particle counts detected in neonatal PN solutions containing cysteine added at the time of compounding does not appear to result in increased precipitate or crystal formation. It is not associated witha decrease in cysteine delivery to patients.

Csp1, a Cold Shock Protein Homolog in Xylella fastidiosa Influences Cell Attachment, Pili Formation, and Gene Expression.

Bacterial cold shock-domain proteins are conserved nucleic acid binding chaperones that play important roles in stress adaptation and pathogenesis. Csp1 is a temperature-independent cold shock protein homolog in Xylella fastidiosa, a bacterial plant pathogen of grapevine and other economically important crops. Csp1 contributes to stress tolerance and virulence in X. fastidiosa. However, besides general single-stranded nucleic acid binding activity, little is known about the specific function(s) of Csp1. To further investigate the role(s) of Csp1, we compared phenotypic differences and transcriptome profiles between the wild type and a csp1 deletion mutant (Δcsp1). Csp1 contributes to attachment and long-term survival and influences gene expression. We observed reduced cell-to-cell attachment and reduced attachment to surfaces with the Δcsp1 strain compared to those with the wild type. Transmission electron microscopy imaging revealed that Δcsp1 was deficient in pili formation compared to the wild type and complemented strains. The Δcsp1 strain also showed reduced survival after long-term growth in vitro. Long-read nanopore transcriptome sequencing (RNA-Seq) analysis revealed changes in expression of several genes important for attachment and biofilm formation in Δcsp1 compared to that in the wild type. One gene of interest, pilA1, which encodes a type IV pili subunit protein, was upregulated in Δcsp1. Deleting pilA1 in X. fastidiosa strain Stag's Leap increased surface attachment in vitro and reduced virulence in grapevines. X. fastidiosa virulence depends on bacterial attachment to host tissue and movement within and between xylem vessels. Our results show that the impact of Csp1 on virulence may be due to changes in expression of attachment genes. IMPORTANCE Xylella fastidiosa is a major threat to the worldwide agriculture industry. Despite its global importance, many aspects of X. fastidiosa biology and pathogenicity are poorly understood. There are currently few effective solutions to suppress X. fastidiosa disease development or eliminate bacteria from infected plants. Recently, disease epidemics due to X. fastidiosa have greatly expanded, increasing the need for better disease prevention and control strategies. Our studies show a novel connection between cold shock protein Csp1 and pili abundance and attachment, which have not been reported for X. fastidiosa. Understanding how pathogenesis-related gene expression is regulated can aid in developing novel pathogen and disease control strategies. We also streamlined a bioinformatics protocol to process and analyze long-read nanopore bacterial RNA-Seq data, which will benefit the research community, particularly those working with non-model bacterial species.

Application of Environment-Friendly Rhamnolipids against Transmission of Enveloped Viruses Like SARS-CoV2.

In the face of new emerging respiratory viruses, such as SARS-CoV2, vaccines and drug therapies are not immediately available to curb the spread of infection. Non-pharmaceutical interventions, such as mask-wearing and social distance, can slow the transmission. However, both mask and social distance have not prevented the spread of respiratory viruses SARS-CoV2 within the US. There is an urgent need to develop an intervention that could reduce the spread of respiratory viruses. The key to preventing transmission is to eliminate the emission of SARS-CoV2 from an infected person and stop the virus from propagating in the human population. Rhamnolipids are environmentally friendly surfactants that are less toxic than the synthetic surfactants. In this study, rhamnolipid products, 222B, were investigated as disinfectants against enveloped viruses, such as bovine coronavirus and herpes simplex virus 1 (HSV-1). The 222B at 0.009% and 0.0045% completely inactivated 6 and 4 log PFU/mL of HSV-1 in 5-10 min, respectively. 222B at or below 0.005% is also biologically safe. Moreover, 50 µL of 222B at 0.005% on ~1 cm2 mask fabrics or plastic surface can inactivate ~103 PFU HSV-1 in 3-5 min. These results suggest that 222B coated on masks or plastic surface can reduce the emission of SARS-CoV2 from an infected person and stop the spread of SARS-CoV2.