Isolation and sequence of the gene for actin in Saccharomyces cerevisiae

The yeast Saccharomyces cerevisiae is known to contain the highly conserved and unbiquitous protein actin. We have used cloned actin sequences from Dictyostelium discoideum to identify and clone the actin gene in yeast. Hybridization to genomic fragments of yeast DNA suggest that there is a single actin gene in yeast. We have determined the nucleotide sequence of that gene and its flanking regions. The sequence of the gene reveals an intervening sequence of 309 base pairs in the coding sequences at the 5' end of the gene. The existence and location of the intervening sequence was verified by using the dideoxy chain termination technique to determine the sequence at the 5' terminus of the actin mRNA. The similarity of the splice junction sequences in this gene to those found in higher eukaryotes suggests that yeast must possess a similar splicing enzyme.

Close relationships and adjustment to a life crisis: the case of breast cancer

When life crises occur, significant others are thought to help alleviate distress and resolve practical problems. Yet life crises may overwhelm significant others, eroding their ability to provide effective support. The accuracy of these contrasting accounts of relationship functioning was evaluated in a study of 102 breast cancer patients and their significant others, interviewed at 4 and 10 months after diagnosis. Results largely confirmed the negative account of relationship functioning. Although significant others provided support in response to patients' physical impairment, they withdrew support in response to patients' emotional distress. Moreover, support from significant others did not alleviate patients' distress or promote physical recovery. These results reveal limits to the effectiveness of close relationships in times of severe stress.

Association of proinflammatory cytokines and chemotherapy-associated cognitive impairment in breast cancer patients: a multi-centered, prospective, cohort study

BACKGROUND

Existing evidence suggests that proinflammatory cytokines play an intermediary role in postchemotherapy cognitive impairment. This is one of the largest multicentered, cohort studies conducted in Singapore to evaluate the prevalence and proinflammatory biomarkers associated with cognitive impairment in breast cancer patients.

PATIENTS AND METHODS

Chemotherapy-receiving breast cancer patients (stages I-III) were recruited. Proinflammatory plasma cytokines concentrations [interleukin (IL)-1β, IL-2, IL-4, IL-6, IL-8, IL-10, granulocyte-macrophage colony-stimulating factor, interferon-γ and tumor necrosis factor-α] were evaluated at 3 time points (before chemotherapy, 6 and 12 weeks after chemotherapy initiation). The FACT-Cog (version 3) was utilized to evaluate patients' self-perceived cognitive disturbances and a computerized neuropsychological assessment (Headminder) was administered to evaluate patients' memory, attention, response speed and processing speed. Changes of cognition throughout chemotherapy treatment were compared against the baseline. Linear mixed-effects models were applied to test the relationships of clinical variables and cytokine concentrations on self-perceived cognitive disturbances and each objective cognitive domain.

RESULTS

Ninety-nine patients were included (age 50.5 ± 8.4 years; 81.8% Chinese; mean duration of education = 10.8 ± 3.3 years). Higher plasma IL-1β was associated with poorer response speed performance (estimate: -0.78; 95% confidence interval (CI) -1.34 to -0.03; P = 0.023), and a higher concentration of IL-4 was associated with better response speed performance (P = 0.022). Higher concentrations of IL-1β and IL-6 were associated with more severe self-perceived cognitive disturbances (P = 0.018 and 0.001, respectively). Patients with higher concentrations of IL-4 also reported less severe cognitive disturbances (P = 0.022).

CONCLUSIONS

While elevated concentrations of IL-6 and IL-1β were observed in patients with poorer response speed performance and perceived cognitive disturbances, IL-4 may be protective against chemotherapy-associated cognitive impairment. This study is important because cytokines would potentially be mechanistic mediators of chemotherapy-associated cognitive changes.

Suppression of the accumulation of triosephosphates and increased formation of methylglyoxal in human red blood cells during hyperglycaemia by thiamine in vitro

The accumulation of triosephosphates and the increased formation of the potent glycating agent methylglyoxal in intracellular hyperglycaemia are implicated in the development of diabetic complications. A strategy to counter this is to stimulate the anaerobic pentosephosphate pathway of glycolysis by maximizing transketolase activity by thiamine supplementation, with the consequent consumption of glyceraldehyde-3-phosphate and increased formation of ribose-5-phosphate. To assess the effect of thiamine supplementation on the accumulation of triosephosphates and methylglyoxal formation in cellular hyperglycaemia, we incubated human red blood cell suspensions (50% v/v) in short-term culture with 5 mM glucose and 50 mM glucose in Krebs-Ringer phosphate buffer at 37 degrees C as models of cellular metabolism under normoglycaemic and hyperglycaemic conditions. In hyperglycaemia, there is a characteristic increase in the concentration of the triosephosphate pool of glycolytic intermediates and a consequent increase in the concentration and metabolic flux of the formation of methylglyoxal. The addition of thiamine (50-500 microM) increased the activity of transketolase, decreased the concentration of the triosephosphate pool, decreased the concentration and metabolic flux of the formation of methylglyoxal, and increased the concentration of total sedoheptulose-7-phosphate and ribose-5-phosphate. Biochemical changes implicated in the development of diabetic complications were thereby prevented. This provides a biochemical basis for high dose thiamine therapy for the prevention of diabetic complications.

Use of myocutaneous flaps for perineal closure following abdominoperineal excision of the rectum for adenocarcinoma

INTRODUCTION

Abdominoperineal excision (APE) following radiotherapy is associated with a high rate of perineal wound complications. The use of myocutaneous flaps may improve wound healing. We present our experience using myocutaneous flaps for immediate reconstruction.

METHOD

Prospective data were collected on patients undergoing APE from October 2003 to December 2008. Patient demographics, operating time, wound complications and length of stay were recorded.

RESULTS

Fifty-one patients underwent APE for rectal adenocarcinoma, 21 had primary closure and 30 had myocutaneous flap closure (24 VRAM, 6 gracilis). The proportion of patients undergoing preoperative radiotherapy in each group were 62% and 93% respectively (P = 0.011). There were no major complications following primary closure of the unirradiated perineum. Major perineal wound complications requiring reoperation or debridement were seen in three (14%) patients following primary closure and five (17%) patients with flap closure. After radiotherapy, closure with a flap reduced the length of stay from 20 to 15 days, but this difference was not statistically significant (P = 0.36).

CONCLUSION

The use of flap closure in irradiated patients is associated with fewer perineal complications and a shorter hospital stay.

Age differences in social preferences among Taiwanese and Mainland Chinese: the role of perceived time

Socioemotional selectivity theory holds that as people recognize the inevitable constraint of time imposed by mortality, their social goals change, motivating them to limit social contacts to those with whom they are emotionally close. This theory was tested among Taiwanese and Mainland Chinese. As predicted, results showed that older adults (aged 60-90 years) in both cultures were more likely than younger adults (aged 18-30 years) to prefer familiar social partners who were most likely to provide emotionally close social interactions. Mainland Chinese, who as a group have shorter actuarial life expectancy, were more likely to prefer familiar social partners than were Taiwanese. These age and cultural differences were eliminated when differences in perceived time were statistically controlled for.

Photopolymerizable chitosan-collagen hydrogels for bone tissue engineering

Photopolymerizable hydrogels derived from naturally occurring polymers have attracted significant interest in tissue-engineering applications due to their excellent biocompatibility, hydrophilic nature favourable for cell ingrowth and ability to be cured in situ through a minimally invasive procedure. In this study, we developed a composite hydrogel consisting of photocrosslinkable methacrylated glycol chitosan (MeGC) and semi-interpenetrating collagen (Col) with a riboflavin photoinitiator under blue light. The incorporation of Col in MeGC hydrogels enhanced the compressive modulus and slowed the degradation rate of the hydrogels. MeGC-Col composite hydrogels significantly enhanced cellular attachment, spreading, proliferation and osteogenic differentiation of mouse bone marrow stromal cells (BMSCs) seeded on the hydrogels compared with pure MeGC hydrogels, as observed by upregulated alkaline phosphatase (ALP) activity as well as increased mineralization. Similarly, when cells were encapsulated within hydrogels, BMSCs exhibited greater proliferation, ALP activity and mineral deposits in the presence of Col. These findings demonstrate that MeGC-Col composite hydrogels may be useful in promoting bone regeneration. Copyright © 2014 John Wiley & Sons, Ltd.

Alteration of polynucleotide secondary structure by ribosomal protein S1

Ribosomal 30S protein S1 causes disruption of the secondary structure of certain pyrimidine-containing polynucleotides. Helical poly(U), poly(C, U), and neutral and acidic poly(C) are stoichiometrically converted by S1 to structures indistinguishable from their partially or completely thermally denatured forms, as revealed by circular dichroism. Of the several double- and triple-stranded helical polynucleotides tested that contain one polypurine strand and at least one polypyrimidine strand, only the conformation of the DNA.RNA hybrid, poly(A)-poly(dT), is perturbed. In the presence of S1, this hybrid undergoes a transition to a new structure that has a circular dichroism spectrum unlike either the native or thermally denatured forms. Intercalated ethidium bromide is released from poly(A)-poly(dT) by S1, confirming the occurrence of a conformational rearrangement. The translation inhibitor, autintricarboxylic acid, completely inhibits the action of S1 on polypyrimidines, but has no effect on the conformational perturbation of poly(A(-poly(dT). The possible relation between these observations and the biological function of protein S1 is discussed.

Mutational and in vitro protein-binding studies on centromere DNA from Saccharomyces cerevisiae

Centromeres on chromosomes in the yeast Saccharomyces cerevisiae contain approximately 140 base pairs (bp) of DNA. The functional centromere (CEN) region contains three important sequence elements (I, PuTCACPuTG; II, 78 to 86 bp of high-AT DNA; and III, a conserved 25-bp sequence with internal bilateral symmetry). Various point mutations or deletions in the element III region have a profound effect on CEN function in vivo, indicating that this DNA region is a key protein-binding site. This has been confirmed by the use of two in vitro assays to detect binding of yeast proteins to DNA fragments containing wild-type or mutationally altered CEN3 sequences. An exonuclease III protection assay was used to demonstrate specific binding of proteins to the element III region of CEN3. In addition, a gel DNA fragment mobility shift assay was used to characterize the binding reaction parameters. Sequence element III mutations that inactivate CEN function in vivo also prevent binding of proteins in the in vitro assays. The mobility shift assay indicates that double-stranded DNAs containing sequence element III efficiently bind proteins in the absence of sequence elements I and II, although the latter sequences are essential for optimal CEN function in vivo.

Preferential expression of antioxidant response element mediated gene expression in astrocytes

Transcriptional control of target genes by antioxidant/electrophile response elements has been well described in peripheral tissues. Genes that are regulated by this mechanism include the antioxidant enzymes NAD(P)H:quinone oxidoreductase, gamma-glutamyl cystine synthetase and glutathione-S-transferase. Antioxidant/electrophile response elements within a gene's promoter confer induction by low-molecular-weight electrophilic compounds such as tert-butylhydroquinone and dimethyl fumarate. We have now examined the ability of antioxidant/electrophile response elements to elicit gene expression in neurons and astrocytes in both brain slices and primary cultures using transient transfection of promoter reporter constructs. Our results using a heat-stable human placental alkaline phosphatase reporter indicate that antioxidant/electrophile response element mediated gene expression is largely restricted to astrocyte cell populations. Placental alkaline phosphatase expression was significantly elevated in astrocytes treated with the antioxidant/electrophile response element inducer dimethyl fumarate. Mutant constructs lacking a functional antioxidant/electrophile response element abolished all placental alkaline phosphatase expression in astrocytes. We suggest that astrocytic metabolic processes that normally aid and/or protect neurons may be controlled via this inducible system.

Performance of a glucose meter with a built-in automated bolus calculator versus manual bolus calculation in insulin-using subjects

BACKGROUND

Patients consider multiple parameters in adjusting prandial insulin doses for optimal glycemic control. Difficulties in calculations can lead to incorrect doses or induce patients to administer fixed doses, rely on empirical estimates, or skip boluses.

METHOD

A multicenter study was conducted with 205 diabetes subjects who were on multiple daily injections of rapid/ short-acting insulin. Using the formula provided, the subjects manually calculated two prandial insulin doses based on one high and one normal glucose test result, respectively. They also determined the two doses using the FreeStyle InsuLinx Blood Glucose Monitoring System, which has a built-in, automated bolus calculator. After dose determinations, the subjects completed opinion surveys.

RESULTS

Of the 409 insulin doses manually calculated by the subjects, 256 (63%) were incorrect. Only 23 (6%) of the same 409 dose determinations were incorrect using the meter, and these errors were due to either confirmed or potential deviations from the study instructions by the subjects when determining dose with meter. In the survey, 83% of the subjects expressed more confidence in the meter-calculated doses than the manually calculated doses. Furthermore, 87% of the subjects preferred to use the meter than manual calculation to determine prandial insulin doses.

CONCLUSIONS

Insulin-using patients made errors in more than half of the manually calculated insulin doses. Use of the automated bolus calculator in the FreeStyle InsuLinx meter minimized errors in dose determination. The patients also expressed confidence and preference for using the meter. This may increase adherence and help optimize the use of mealtime insulin.

Nasopharyngeal brush biopsies and detection of nasopharyngeal cancer in a high-risk population

BACKGROUND

Nasopharyngeal carcinoma (NPC) is an important tumor in many countries. Ethnic and regional factors strongly influence disease risk. NPC is usually diagnosed late in disease development, and 10-year survival rates are as low as 10%. Epstein-Barr virus (EBV), a possibly causative agent, is present in all cells of essentially all undifferentiated NPCs. We wished to determine the following: 1) whether an ambulatory nasopharyngeal brush biopsy could provide sufficient tumor cell DNA for the detection of EBV and 2) whether the detection of EBV in this locale reflects the presence of tumor cells or simply EBV carrier status.

METHODS

We collected nasopharyngeal tissue via ambulatory brush biopsies from 21 patients with newly diagnosed NPC and from 157 subjects with other otolaryngologic complaints. The majority of study subjects were from high-risk populations. Sample DNA was analyzed for the presence of EBV genomic sequences by use of the polymerase chain reaction (PCR).

RESULTS

Ninety-six percent of samples yielded sufficient DNA for PCR amplification. Nineteen of 21 patients with NPC brushed positive for EBV DNA, while all but two (1.3%) of 149 informative control subjects were negative for EBV (two-sided P<.0001). One of the EBV-positive control subjects had an EBV-positive inverted sinonasal papilloma; the other EBV-positive control subject exhibited no overt clinical disease.

CONCLUSION

Demonstration of EBV DNA in nasopharyngeal brush biopsy specimens detects NPC with a sensitivity of at least 90% (95% confidence interval = 89.63%-91.32%) and a specificity of approximately 99% (95% confidence interval = 98.64%-98.68%). This technique merits further testing as a possible ambulatory screening strategy in high-risk populations.

Decontaminating N95 and SN95 masks with ultraviolet germicidal irradiation does not impair mask efficacy and safety

Inadequate supply of filtering facepiece respirators (FFRs) for healthcare workers during a pandemic such as the novel coronavirus outbreak (SARS-CoV-2) is a serious public health issue. The aim of this study was to synthesize existing data on the effectiveness of ultraviolet germicidal irradiation (UVGI) for N95 FFR decontamination. A systematic review (PROSPERO CRD42020176156) was conducted on UVGI in N95 FFRs using Embase, Medline, Global Health, Google Scholar, WHO feed, and MedRxiv. Two reviewers independently determined eligibility and extracted predefined variables. Original research reporting on function, decontamination, or mask fit following UVGI were included. Thirteen studies were identified, comprising 54 UVGI intervention arms and 58 N95 models. FFRs consistently maintained certification standards following UVGI. Aerosol penetration averaged 1.19% (0.70-2.48%) and 1.14% (0.57-2.63%) for control and UVGI arms, respectively. Airflow resistance for the control arms averaged 9.79 mm H₂O (7.97-11.70 mm H₂O) vs 9.85 mm H₂O (8.33-11.44 mm H₂O) for UVGI arms. UVGI protocols employing a cumulative dose >20,000 J/m² resulted in a 2-log reduction in viral load. A >3-log reduction was observed in seven UVGI arms using >40,000 J/m². Impact of UVGI on fit was evaluated in two studies (16,200; 32,400 J/m²) and no evidence of compromise was found. Our findings suggest that further work in this area (or translation to a clinical setting) should use a cumulative UV-C dose of 40,000 J/m² or greater, and confirm appropriate mask fit following decontamination.

Close relationships and adjustment to a life crisis: the case of breast cancer

When life crises occur, significant others are thought to help alleviate distress and resolve practical problems. Yet life crises may overwhelm significant others, eroding their ability to provide effective support. The accuracy of these contrasting accounts of relationship functioning was evaluated in a study of 102 breast cancer patients and their significant others, interviewed at 4 and 10 months after diagnosis. Results largely confirmed the negative account of relationship functioning. Although significant others provided support in response to patients' physical impairment, they withdrew support in response to patients' emotional distress. Moreover, support from significant others did not alleviate patients' distress or promote physical recovery. These results reveal limits to the effectiveness of close relationships in times of severe stress.

Correlation of changes between 2-year disease-free survival and 5-year overall survival in adjuvant breast cancer trials from 1966 to 2006

BACKGROUND

Although disease-free survival (DFS) is accepted as a valid end point in adjuvant breast cancer trials, improvement in 2-year DFS has never been formally established as an adequate correlate for 5-year overall survival (OS). We set out to ascertain if changes in 2-year DFS can be used to accurately predict 5-year OS changes.

DESIGN

We conducted a systematic Medline search (1966-2006) for randomized adjuvant breast cancer trials of >100 patients per arm with 2-year DFS and 5-year OS data. A univariate regression model weighted by trial sample size was constructed to determine whether 2-year DFS differences between treatment arms within trials were predictive of 5-year OS differences.

RESULTS

A total of 126 studies containing 149 treatment comparisons met the inclusion criteria. Difference in 2-year DFS was a significant predictor of difference in 5-year OS. For every 1% increase in 2-year DFS difference, the 5-year OS difference increased by 0.5%-0.55%. The proportion of variation explained ranged from 0.38 to 0.42, with a wide prediction interval.

CONCLUSION

There is a statistically significant correlation, of moderate strength, between difference in 2-year DFS between treatment comparisons and difference in 5-year OS but the correlation is not strong enough to be used as a predictor.

Near patient blood ketone measurements and their utility in predicting diabetic ketoacidosis

AIM

To assess the utility of near patient blood ketone measurements in predicting diabetic ketoacidosis (DKA) among a group of hyperglycaemic unwell patients presenting to a hospital emergency department.

METHODS

Near patient blood beta-hydroxybutyrate (beta-OHB) testing has recently been introduced as a new tool in our hospital Accident and Emergency department (A&E) for patients with a finger-prick glucose of > 11 mmol/l. We reviewed the records of the first 50 patients to have a beta-OHB measurement to establish if they developed DKA or received treatment with intravenous insulin within 48 h of presentation. We then compared the diagnostic power of beta-OHB measurements with other clinical, physiological and biochemical markers of DKA.

RESULTS

Nine patients had DKA, eight had a compensated metabolic acidosis secondary to raised serum ketones, and 33 had no evidence of DKA during the following 48 h. The median (range) beta-OHB levels in each group were 6.0 (3.1-6.0) mmol/l, 3.4 (1.2-5.7) mmol/l, and 0.1 (0.0-1.2) mmol/l, respectively. A beta-OHB level of > or = 3.0 mmol/l had a sensitivity of 100% and specificity of 88% for DKA. All those with beta-OHB level > 3.0 mmol/l required treatment with intravenous insulin.

CONCLUSION

Measuring beta-OHB when a hyperglycaemic patient is identified could offer a simple method of identifying at an early stage those patients at highest risk of DKA (beta-OHB > 3.0 mmol/l), and redirecting the search for a diagnosis in others (beta-OHB < 1.0 mmol/l).

Low medical morbidity and mortality after acute courses of electroconvulsive therapy in a population-based sample

BACKGROUND

To determine event rates for specific medical events and mortality among individuals receiving electroconvulsive therapy (ECT).

METHOD

Population-based cohort study using health administrative data of acute ECT treatments delivered in Ontario, Canada, from 2003 to 2011. We measured the following medical event rates, per 10 000 ECT treatments, up to 7 and 30 days post-treatment: stroke, seizure, acute myocardial infarction, arrhythmia, pneumonia, pulmonary embolus, deep vein thrombosis, gastrointestinal bleeding, falls, hip fracture, and mortality.

RESULTS

A total of 135 831 ECT treatments were delivered to 8810 unique patients. Overall medical event rates were 9.1 and 16.8 per 10 000 ECT treatments respectively. The most common medical events were falls (2.7 and 5.5 per 10 000 ECT treatments) and pneumonia (1.8 and 3.8 per 10 000 ECT treatments). Fewer than six deaths occurred on the day of an ECT treatment. This corresponded to a mortality rate of less than 0.4 per 10 000 treatments. Deaths within 7 and 30 days of an ECT treatment, excluding deaths due to external causes (e.g., accidental and intentional causes of death), were 1.0 and 2.4 per 10 000 ECT treatments respectively.

CONCLUSION

Morbidity and mortality events after ECT treatments were relatively low, supporting ECT as a low-risk medical procedure.

Patient mutations linked to arrhythmogenic cardiomyopathy enhance calpain-mediated desmoplakin degradation

Arrhythmogenic cardiomyopathy (ACM) is an inherited disorder with variable genetic etiologies. Here we focused on understanding the precise molecular pathology of a single clinical variant in DSP, the gene encoding desmoplakin. We initially identified a novel missense desmoplakin variant (p.R451G) in a patient diagnosed with biventricular ACM. An extensive single-family ACM cohort was assembled, revealing a pattern of coinheritance for R451G desmoplakin and the ACM phenotype. An in vitro model system using patient-derived induced pluripotent stem cell lines showed depressed levels of desmoplakin in the absence of abnormal electrical propagation. Molecular dynamics simulations of desmoplakin R451G revealed no overt structural changes, but a significant loss of intramolecular interactions surrounding a putative calpain target site was observed. Protein degradation assays of recombinant desmoplakin R451G confirmed increased calpain vulnerability. In silico screening identified a subset of 3 additional ACM-linked desmoplakin missense mutations with apparent enhanced calpain susceptibility, predictions that were confirmed experimentally. Like R451G, these mutations are found in families with biventricular ACM. We conclude that augmented calpain-mediated degradation of desmoplakin represents a shared pathological mechanism for select ACM-linked missense variants. This approach for identifying variants with shared molecular pathologies may represent a powerful new strategy for understanding and treating inherited cardiomyopathies.

A test for intron function in the yeast actin gene

Many eukaryotic genes contain intervening sequences (IVS), but the rationale for their existence remains a mystery. Previous studies done in our laboratory demonstrated that the intron in a yeast tRNATyr gene, SUP6, does have a function. We used the same approach to determine the role of introns in nuclear genes encoding messenger RNAs. A single actin gene with one intron exists in Saccharomyces cerevisiae. The level of actin in yeast appears to be crucial to viability: either too much or too little actin inhibits growth. Therefore, small effects on synthesis of actin protein resulting from the removal of the actin gene intron would be expected to cause measurable changes in cell growth. In the present study, an intron-deleted actin gene was constructed in vitro and was used to replace the single resident actin gene in a haploid strain. Analysis of the cells carrying the intron-deleted actin gene shows that the intervening sequence is not essential for actin gene expression.

Correcting the anion gap for hypoalbuminaemia does not improve detection of hyperlactataemia

BACKGROUND

An elevated lactate level reflects impaired tissue oxygenation and is a predictor of mortality. Studies have shown that the anion gap is inadequate as a screen for hyperlactataemia, particularly in critically ill and trauma patients. A proposed explanation for the anion gap's poor sensitivity and specificity in detecting hyperlactataemia is that the serum albumin is frequently low. This study therefore, sought to compare the predictive values of the anion gap and the anion gap corrected for albumin (cAG) as an indicator of hyperlactataemia as defined by a lactate > or =2.5 mmol/l.

METHODS

A retrospective review of 639 sets of laboratory values from a tertiary care hospital. Patients' laboratory results were included in the study if serum chemistries and lactate were drawn consecutively. The sensitivity, specificity, and predictive values were obtained. A receiver operator characteristics curve (ROC) was drawn and the area under the curve (AUC) was calculated.

RESULTS

An anion gap > or =12 provided a sensitivity, specificity, positive predictive value, and negative predictive value of 39%, 89%, 79%, and 58%, respectively, and a cAG > or =12 provided a sensitivity, specificity, positive predictive value, and negative predictive value of 75%, 59%, 66%, and 69%, respectively. The ROC curves between anion gap and cAG as a predictor of hyperlactataemia were almost identical. The AUC was 0.757 and 0.750, respectively.

CONCLUSIONS

The sensitivities, specificities, and predictive values of the anion gap and cAG were inadequate in predicting the presence of hyperlactataemia. The cAG provides no additional advantage over the anion gap in the detection of hyperlactataemia.

Age differences in social preferences among Taiwanese and Mainland Chinese: the role of perceived time

Socioemotional selectivity theory holds that as people recognize the inevitable constraint of time imposed by mortality, their social goals change, motivating them to limit social contacts to those with whom they are emotionally close. This theory was tested among Taiwanese and Mainland Chinese. As predicted, results showed that older adults (aged 60-90 years) in both cultures were more likely than younger adults (aged 18-30 years) to prefer familiar social partners who were most likely to provide emotionally close social interactions. Mainland Chinese, who as a group have shorter actuarial life expectancy, were more likely to prefer familiar social partners than were Taiwanese. These age and cultural differences were eliminated when differences in perceived time were statistically controlled for.

Efficacy and safety of disinfectants for decontamination of N95 and SN95 filtering facepiece respirators: a systematic review

BACKGROUND

Decontaminating and reusing filtering facepiece respirators (FFRs) for healthcare workers is a potential solution to address inadequate FFR supply during a global pandemic.

AIM

The objective of this review was to synthesize existing data on the effectiveness and safety of using chemical disinfectants to decontaminate N95 FFRs.

METHODS

A systematic review was conducted on disinfectants to decontaminate N95 FFRs using Embase, Medline, Global Health, Google Scholar, WHO feed, and MedRxiv. Two reviewers independently determined study eligibility and extracted predefined data fields. Original research reporting on N95 FFR function, decontamination, safety, or FFR fit following decontamination with a disinfectant was included.

FINDINGS AND CONCLUSION

A single cycle of vaporized hydrogen peroxide (H₂O₂) successfully removes viral pathogens without affecting airflow resistance or fit, and maintains an initial filter penetration of <5%, with little change in FFR appearance. Residual hydrogen peroxide levels following decontamination were within safe limits. More than one decontamination cycle of vaporized H₂O₂ may be possible but further information is required on how multiple cycles would affect FFR fit in a real-world setting before the upper limit can be established. Although immersion in liquid H₂O₂ does not appear to adversely affect FFR function, there is no available data on its ability to remove infectious pathogens from FFRs or its impact on FFR fit. Sodium hypochlorite, ethanol, isopropyl alcohol, and ethylene oxide are not recommended due to safety concerns or negative effects on FFR function.