Impact of artificial accelerated ageing of PVC surfaces and surface degradation on disinfectant efficacy

BACKGROUND

Standardized efficacy surface tests for disinfectants are performed on pristine surfaces. There is a growing interest in understanding the impact of surface ageing on disinfectant activity, owing for example to the increased usage of ultraviolet (UV) radiation and oxidative chemistries for surface decontamination. This acknowledges that general surface 'wear and tear' following UV radiation and oxidative biocide exposure may impact biocidal product efficacy.

METHODS

PVC surfaces were aged through thermal and UV-A radiation (340 nm wavelength) following the use of standard ageing surface protocols to simulate natural surface degradation. Surface roughness, contact angle and scanning electron microscopy were performed to evaluate physical changes in PVC surfaces before and after artificial ageing. The efficacy of five pre-impregnated disinfectant wipes were evaluated using the ASTM E2967-15 on stainless-steel (control) and PVC surfaces (aged and non-aged).

RESULTS

The type of formulation and the organism tested remained the most significant factors impacting disinfectant efficacy, compared with surface type. Both thermal ageing and UV-A exposure of PVC surfaces clearly showed signs of surface degradation, notably an increase in surface roughness. Physical changes were observed in the roughness of PVC after artificial ageing. A difference in disinfectant efficacy dependent on aged PVC surfaces was observed for some, but not all formulations.

CONCLUSION

We showed that surface type and surface ageing can affect biocidal product efficacy, although in a non-predictable manner. More research is needed in this field to ascertain whether surface types and aged surfaces should be used in standardized efficacy testing.

Efficacy of DYRK1A inhibitors in novel models of Down syndrome acute lymphoblastic leukemia

Not available.

Evaluating the antimicrobial efficacy of long-lasting hand sanitizers on skin

BACKGROUND

The microbicidal efficacy of hand sanitizer formulations is usually measured through standardized quantitative suspension tests and fingerpad tests; these cannot evaluate long-lasting formulations or are impractical due to biological risks, high cost, or time required for testing. With increased numbers of long-lasting microbicidal activity claims of commercially available hand sanitizers, alternative testing strategies are required.

AIM

To explore the use of a standardized ex-vivo pig skin model to reproducibly measure long-lasting efficacy of an alcohol-free hand sanitizer formulation.

METHODS

The microbicidal efficacy of an alcohol-free hand sanitizer was tested against Staphylococcus aureus, Escherichia coli and Klebsiella pneumoniae, and the enveloped virus SARS-CoV-2 with quantitative suspension tests (EN13727 and EN14476) with a contact time of 5 min. The product was then tested over a 6 h period using an ex-vivo pig skin model with a modified version of PAS 2424 to simulate the impact of skin abrasion.

FINDINGS

Quantitative suspension tests yielded a >5 log10 reduction for all organisms tested within a 5 min contact time. Pig skin tests showed reduced but consistent efficacy at all time points and indicated no significant impact of abrasion on efficacy.

CONCLUSION

The use of the ex-vivo pig skin model provides a potentially viable and convenient model system to test long-lasting hand sanitizer formulations, providing a path for sustainable hand sanitizer formulation claims of activity on skin.

The effect of intestinal microbiota dysbiosis on growth and detection of carbapenemase-producing Enterobacterales within an in vitro gut model

BACKGROUND

Carbapenemase-producing Enterobacterales (CPE) can colonize the gut and are of major clinical concern. Identification of CPE colonization is problematic; there is no gold-standard detection method, and the effects of antibiotic exposure and microbiota dysbiosis on detection are unknown.

AIM

Based on a national survey we selected four CPE screening assays in common use. We used a clinically reflective in vitro model of human gut microbiota to investigate the performance of each test to detect three different CPE strains under different, clinically relevant antibiotic exposures.

METHODS

Twelve gut models were seeded with a pooled faecal slurry and exposed to CPE either before, after, concomitant with, or in the absence of piperacillin-tazobactam (358 mg/L, 3 × daily, seven days). Total Enterobacterales and CPE populations were enumerated daily. Regular screening for CPE was performed using Cepheid Xpert® Carba-R molecular test, and with Brilliance™ CRE, Colorex™ mSuperCARBA and CHROMID® CARBA SMART agars.

FINDINGS

Detection of CPE when the microbiota are intact is problematic. Antibiotic exposure disrupts microbiota populations and allows CPE proliferation, increasing detection. The performances of assays varied, particularly with respect to different CPE strains. The Cepheid assay performed better than the three agar methods for detecting a low level of CPE within an intact microbiota, although performance of all screening methods was comparable when CPE populations increased in a disrupted microbiota.

CONCLUSION

CPE strains differed in their dynamics of colonization in an in vitro gut model and in their subsequent response to antibiotic exposure. This affected detection by molecular and screening methods, which has implications for the sensitivity of CPE screening in healthcare settings.

Mutational analysis of the HIV-1 LTR as a promoter of negative sense transcription

The HIV-1 gene promoter is a bi-directional promoter of transcription. We report the characterization of the negative sense promoter (NSP) by analysis of the effect on negative sense transcription of a series of LTR U3 region substitution mutants. Mutations in the region nt -58 to -183 (positive sense transcription initiation nt +1) reduced transcription to <15% of wild type NSP activity. This region, essential for NSP activity, was designated the core basal promoter. Over expression of NF-kappaB RelA(p65) and LEF-1 increased negative sense expression, as did over expression of H-ras oncogene, consistent with the presence of cognate sequence motifs for NF-kappaB, LEF-1 and RBF. We were also able to confirm that the NSP is a TATA-less promoter inhibited by HIV-1 Tat. Based on our findings, we propose a model for the interaction between the NSP and PSP, and the role of Tat in regulating the interaction.

A multi-centre study of Osseotite implants supporting mandibular restorations: a 3-year report

This multi-centre study evaluated the performance of the Osseotite implant in the mandibular arch. Osseotite implants (n = 688) were placed in 172 patients; 43.5% were placed in the anterior mandible and 66.5% in the posterior mandible. Fifteen per cent of the implants were placed in soft bone, 56.9% in normal bone and 28.1% in dense bone. During placement, 49.9% of the implants were identified as having a tight fit, 48.6% a firm fit and 1.5% a loose fit. About one-third of the implants (32.4%) were short (10 mm in length or less). After 36 months, only 5 implants had been lost, for a cumulative survival rate of 99.3%. The 3-year results of this study indicate a high degree of predictability with placement of Osseotite implants in the mandibular arch.

A compilation of cellular transcription factor interactions with the HIV-1 LTR promoter

The human immunodeficiency virus type 1 (HIV-1) long terminal repeat (LTR) represents a model promoter system and the identification and characterisation of cellular proteins that interact with this region has provided a basic understanding about both general eukaryotic and HIV-1 proviral transcriptional regulation. To date a large number of sequence-specific DNA-protein interactions have been described for the HIV-1 LTR. The aim of this report is to provide a comprehensive, updated listing of these HIV-1 LTR interactions. It is intended as a reference point to facilitate on-going studies characterising the identity of cellular proteins interacting with the HIV-1 LTR and the functional role(s) of specific regions of the LTR for HIV-1 replication.

Patterns of single-nucleotide polymorphisms in candidate genes for blood-pressure homeostasis

Sequence variation in human genes is largely confined to single-nucleotide polymorphisms (SNPs) and is valuable in tests of association with common diseases and pharmacogenetic traits. We performed a systematic and comprehensive survey of molecular variation to assess the nature, pattern and frequency of SNPs in 75 candidate human genes for blood-pressure homeostasis and hypertension. We assayed 28 Mb (190 kb in 148 alleles) of genomic sequence, comprising the 5' and 3' untranslated regions (UTRs), introns and coding sequence of these genes, for sequence differences in individuals of African and Northern European descent using high-density variant detection arrays (VDAs). We identified 874 candidate human SNPs, of which 22% were confirmed by DNA sequencing to reveal a discordancy rate of 21% for VDA detection. The SNPs detected have an average minor allele frequency of 11%, and 387 are within the coding sequence (cSNPs). Of all cSNPs, 54% lead to a predicted change in the protein sequence, implying a high level of human protein diversity. These protein-altering SNPs are 38% of the total number of such SNPs expected, are more likely to be population-specific and are rarer in the human population, directly demonstrating the effects of natural selection on human genes. Overall, the degree of nucleotide polymorphism across these human genes, and orthologous great ape sequences, is highly variable and is correlated with the effects of functional conservation on gene sequences.

Genomic structure of the gene for the SH2 and pleckstrin homology domain-containing protein GRB10 and evaluation of its role in Hirschsprung disease

Hirschsprung disease (HSCR), or congenital aganglionic megacolon, is the most frequent cause of congenital bowel obstruction. Germline mutations in the RET receptor tyrosine kinase have been shown to cause HSCR. Mice that carry null alleles for RET or for its ligand, glial cell line-derived neurotrophic factor (GDNF), both exhibit complete intestinal aganglionosis and renal defects. Recently, the Src homology 2 (SH2) domain-containing protein Grb10 has been shown to interact with RET in vitro and in vivo, early in development. We have confirmed the map location of GRB10 on human chromosome 7, isolated human BACs containing the gene, elucidated its genomic structure, isolated a highly polymorphic microsatellite marker adjacent to exon 14 and scanned the gene for mutations in a large panel of HSCR patients. No evidence of linkage was detected in HSCR kindreds and no mutations were found in patients. These data suggest that while GRB10 may be important for signal transduction in developing embryos, it does not play an obvious role in HSCR.

Human GFRA1: cloning, mapping, genomic structure, and evaluation as a candidate gene for Hirschsprung disease susceptibility

Congenital aganglionic megacolon, commonly known as Hirschsprung disease (HSCR), is the most frequent cause of congenital bowel obstruction. Germline mutations in the RET receptor tyrosine kinase have been shown to cause HSCR. Knockout mice for RET and for its ligand, glial cell line-derived neurotrophic factor (GDNF), exhibit both complete intestinal aganglionosis and renal defects. Recently, GDNF and GFRA1 (GDNF family receptor, also known as GDNFR-alpha), its GPI-linked coreceptor, were demonstrated to be components of a functional ligand for RET. Moreover, GDNF has been implicated in rare cases of HSCR. We have mapped GFRA1 to human chromosome 10q25, isolated human and mouse genomic clones, determined the gene's intron-exon boundaries, isolated a highly polymorphic microsatellite marker adjacent to exon 7, and scanned for GFRA1 mutations in a large panel of HSCR patients. No evidence of linkage was detected in HSCR kindreds, and no sequence variants were found to be in significant excess in patients. These data suggest that GFRA1'S role in enteric neurogenesis in humans remains to be elucidated and that RET signaling in the gut may take place via alternate pathways, such as the recently described GDNF-related molecule neurturin and its GFRA1-like coreceptor, GFRA2.

Detection of time-dependent and oxidatively induced antigens of bovine liver rhodanese with monoclonal antibodies

Rhodanese has been extensively utilized as a model protein for the study of enzyme structure-function relationships. An immunological study of conformational changes occurring in rhodanese as a result of oxidation or thermal inactivation was conducted. Three monoclonal antibodies (MABs) to rhodanese were produced. Each MAB recognized a unique epitope as demonstrated by binding of the MABs to different proteolytic fragments of rhodanese. While none of the MABs significantly bound native, soluble, sulfur-substituted bovine rhodanese, as indicated in indirect enzyme-linked immunosorbent assay experiments, each MAB was immunoadsorbed from solution by soluble rhodanese as a function of the time rhodanese was incubated at 37 degrees C. Thus, as rhodanese was thermally inactivated, conformational changes resulted in the expression of three new epitopes. Catalytic conformers demonstrated different rates of thermally induced antigen expression. Each MAB also recognized epitopes expressed when rhodanese was immobilized on microtiter plates at 37 degrees C. Two conformers resulting from oxidation of rhodanese by hydrogen peroxide were identified immunologically. All MABs recognized rhodanese that was oxidized with peroxide and allowed to undergo a secondary cyanide-dependent reaction which also resulted in a fluorescence shift and increased proteolytic susceptibility. Only one MAB was capable of recognizing an epitope expressed when rhodanese was oxidized with peroxide and then separated from the reactants to prevent induction of the secondary conformational changes.

Umbilical serum DHAS and total oestriol in relation to gestational age and mode of delivery

The concentrations of mixed umbilical cord serum dehydroepiandrosterone sulphate (DHAS) and total oestriol, were determined by radioimmunoassay in 301 infants. Of 280 infants born between 36 and 42 weeks of gestation, 260 were born by vaginal delivery and 20 were delivered by Caesarean (C-section). We found that there was a significant elevation of serum total oestriol (P < 0.005) after 35 weeks with no concomitant gestational change of DHAS. Within the vaginal delivery group steroid values were similar among infants born following spontaneous, oxytocin augmented, and oxytocin induced labour. Within the C-section delivery group, steroid values were similar in infants who experienced spontaneous labour and those who did not. However, DHAS level was significant higher (P < 0.005) in the vaginal delivery group than in the C-section group. We postulate that the higher DHAS levels in the vaginal delivery group are the result of stress during the late first stage of labour or later.

An interstitial deletion of chromosome 9 in a girl with multiple congenital anomalies

An infant with peculiar facies, coloboma of both eyes, and developmental retardation was found to have d de novo interstitial deletion of the secondary constriction and some adjacent euchromatin on one of her No. 9 chromosomes, del(9)(q11q21). Since studies on duplications, variants, and the molecular composition of the secondary constriction suggest that it contributes little if any information necessary to normal development, deletion of the euchromatin alone is most probably responsible for the clinical findings.

Serum dehydroepiandrosterone sulfate in premature infants and infants with intrauterine growth retardation

Serum dehydroepiandrosterone sulfate (DHAS) was measured by radioimmunoassay in blood samples obtained in 128 ill newborn infants. Serial sampling was carried out in 40 infants. There were wide ranges found in the values in all gestational age groups, and there were not significant differences in the first day of life between DHAS levels in less than 30 week gestation prematures, 6819 +/- 4631 (SD) ng/ml, and near term or term infants, 4307 +/- 1498 ng/ml. Mean DHAS concentrations did not decline over the first three weeks of life in prematures less than 36 weeks gestation. In six infants, age 35-73 days, and 29-34 weeks gestation at birth, the DHAS concentration was 1068 +/- 138 ng/ml. High concentrations were frequent in prematures less than 33 weeks gestation and could be correlated to epiodes of severe clinical stress. There were no significant differences in serum DHAS levels, on the first day of life, between infants with no hyaline membrane disease, nonfatal hyaline membrane disease and fatal hyaline membrane disease. Intrauterine growth retarded (IUGR) infants, who were greater than 35 weeks gestation, had significantly lower (P less than .032) DHAS levels in the first day of life than normally grown infants. The results show that there is a persistence during the postnatal period of the prominent delta5-3beta-hydroxysteroid production by the adrenal cortex characteristic of the fetus. Low concentrations of serum DHAS in IUGR infants suggest that the fetal zone of the neonatal adrenal cortex is a major source of circulating DHAS in the newborn period.