Behavioural insights and attitudes on community masking during the initial spread of COVID-19 in Hong Kong.

INTRODUCTION: Community face mask use during the coronavirus disease 2019 (COVID-19) pandemic has considerably differed worldwide. Generally, Asians are more inclined to wear face masks during disease outbreaks. Hong Kong has emerged relatively unscathed during the initial outbreak of COVID-19, despite its dense population. Previous infectious disease outbreaks influenced the local masking behaviour and response to public health measures. Thus, local behavioural insights are important for the successful implementation of infection control measures. This study explored the behaviour and attitudes of wearing face masks in the community during the initial spread of COVID-19 in Hong Kong. METHODS: We observed the masking behaviour of 10 211 pedestrians in several regions across Hong Kong from 1 to 29 February 2020. We supplemented the data with an online survey of 3199 respondents' views on face mask use. RESULTS: Among pedestrians, the masking rate was 94.8%; 83.7% wore disposable surgical masks. However, 13.0% wore surgical masks incorrectly with 42.5% worn too low, exposing the nostrils or mouth; 35.5% worn 'inside-out' or 'upside-down'. Most online respondents believed in the efficacy of wearing face mask for protection (94.6%) and prevention of community spread (96.6%). Surprisingly, 78.9% reused their mask; more respondents obtained information from social media (65.9%) than from government websites (23.2%). CONCLUSIONS: In Hong Kong, members of the population are motivated to wear masks and believe in the effectiveness of face masks against disease spread. However, a high mask reuse rate and errors in masking techniques were observed. Information on government websites should be enhanced and their accessibility should be improved.

Functional expression of the genomic DNA sequences encoding mouse Na,K-ATPase alpha 1 gene by cotransfection of overlapping genomic DNA segments.

The entire 33-kb coding region of the mouse Na,K-ATPase alpha 1 subunit gene was cloned in two overlapping cosmids which contain inserts of 40 kb. To assess the functional expression of the mouse alpha 1 gene, the two cosmids were cotransfected into ouabain-sensitive CV-1 monkey cells yielding an average of 64 resistant colonies per 10(6) cells per microgram of DNA. Analysis of the DNA transferred to the ouabain-resistant transformants by the two cosmids suggests that the generation of a functional gene can occur by homologous recombination between the two introduced segments, as demonstrated by generation of a novel diagnostic restriction fragment. The ability to reconstruct the intact mouse alpha 1 gene in a heterologous host cell and to monitor its functional expression with a selection protocol permits direct identification and isolation of regulatory sequences for the gene.

Synthesis and anti-HIV activity of isonucleosides.

A series of isomeric 2',3'-dideoxynucleosides which contains a modified carbohydrate moiety has been prepared. This class of compounds was designed to mimic the activity of known anti-HIV dideoxynucleosides, while imparting enhanced chemical and enzymatic stability. Isonucleosides containing the standard heterocyclic bases (A, C, G, T) were synthesized via nucleophilic addition of the base to an isomeric sugar unit. Modified derivatives were generated by manipulation of the intact isonucleoside. Two of the compound prepared, iso-ddA (1) and iso-ddG (6), exhibit significant and selective anti-HIV activity, as well as beneficial hydrolytic stability.

Mesoprefrontal dopaminergic neurons: can tyrosine availability influence their functions?

The dopamine (DA) neurons projecting to the prefrontal cortex (PFC) are thought to be involved in working memory, stress response, and the pathogenesis of schizophrenia. In this commentary, we review the current evidence supporting a precursor tyrosine dependence of these mesoprefrondal DN neurons. Several studies in rats employing different experimental paradigms [i.e. experimental diabetes and early-treated phenylketonuria (PKU) model] have shown that reduced tyrosine levels in brain can affect markedly the physiology and functions of these DA neurons. However, supplemental tyrosine is effective in enhancing functional transmitter outflow from mesoprefrontal DA neurons only under conditions where their physiological activity is enhanced and DA synthesis and release are uncoupled from intrinsic regulatory controls. Recent studies in humans have also suggested that variations in brain tyrosine levels can affect significantly higher cortical functions subserved by the PFC. In early-treated PKU patients with mildly reduced tyrosine levels, marked impairments in cognitive functions dependent on the dorsolateral PFC could be detected. In drug-treated schizophrenic patients, supplemental tyrosine was shown to have a disruptive effects on the smooth-pursuit eye movement performance task. Furthermore, tyrosine administration was effective in restoring impaired working memory in humans following cold stress paradigm, as assessed by a computer-based delayed matching to-sample memory task. These human studies, together with the current evidence obtained from animal experiments, suggest that the functions of the mesoprefrontal DA neurons can, under certain circumstances, be readily influenced by the availability of the precursor tyrosine.

Substance K and substance P differentially modulate mesolimbic and mesocortical systems.

The newly discovered peptide substance K (SK) is an aliphatic tachykinin structurally related to the aromatic tachykinin substance P (SP). Immunohistochemical examination showed a close association between SK afferents and dopamine (DA) cell bodies. Examination of the possible role of SK in modulating midbrain DA systems revealed that SP, but not SK, is associated with the stress response of the mesocortical system. Ventral tegmental area injections of SK effected locomotor hyperactivity, a mesolimbic-mediated behavior. Ventral tegmental injections of SP, but not SK, activated DA metabolism in the prefrontal cortex, while SK injections altered DA metabolism in the nucleus accumbens, but not the cortical site. These data suggest that SK and SP may differentially modulate the mesolimbic and mesocortical systems.

Footshock and conditioned stress increase 3,4-dihydroxyphenylacetic acid (DOPAC) in the ventral tegmental area but not substantia nigra.

The effects of stress on dopamine (DA) metabolism in the mesencephalic DA cell body areas and DA terminal field regions were examined. Both mild footshock stress and exposure to a neutral stimulus previously paired with footshock resulted in a selective increase in the levels of the DA metabolite 3,4-dihydroxyphenylacetic acid (DOPAC) in the prefrontal cortex as has been previously reported. Footshock stress also resulted in a slight but significant increase in DOPAC levels in the olfactory tubercles. DOPAC levels were selectively increased in the A10 cell body area (ventral tegmental area) but not A9 region (substantia nigra) by both footshock and the conditioned stress paradigm. These data indicate that the cell bodies of origin of the mesocortical dopaminergic system are activated by stress in contrast to those DA neurons innervating the striatum. It appears that mesocortical dopaminergic neurons exhibit different regulatory features than mesolimbic or nigrostriatal neurons.

Mild footshock stress dissociates substance P from substance K and dynorphin from Met- and Leu-enkephalin.

Mild footshock stress selectively activates ventral tegmental area dopamine neurons innervating the prefrontal cortex. The same stressor rapidly dissociates ventral tegmental substance P from its preprotachykinin-derived co-transmitter substance K, and preproenkephalin B-derived dynorphin B from preproenkephalin A-derived Met-enkephalin-Arg-Gly-Leu and Leu-enkephalin. Mild footshock stress may provide a paradigm for studying both peptidergic modulation of brain dopaminergic neurons and the dynamic regulation of tachykinin and opioid peptide transcription, processing and utilization.

Mesolimbic and mesocortical dopamine activation induced by phencyclidine: contrasting pattern to striatal response.

The effects of acute administration of phencyclidine, an indirect dopamine agonist, on biochemical indices of dopaminergic activation were examined in mesocortical, mesolimbic and nigrostriatal regions of the rat. High doses (10 mg/kg) of phencyclidine resulted in a marked increase in levels of the dopamine metabolites 3,4-dihydroxyphenylacetic acid and homovanillic acid in all mesolimbic and mesocortical sites examined, as well as in the ventral tegmental area, source of the dopaminergic innervation of mesolimbic/cortical sites. In contrast, levels of both metabolites decreased in the striatum and tended to decrease in the substantia nigra, source of the striatal dopaminergic innervation. The metabolite response to phencyclidine was dose-related. These data indicate that the mesolimbic and mesocortical dopaminergic neurons are activated by phencyclidine. Since the firing rate of both A10 (ventral tegmental area) and A9 (substantia nigra) dopamine neurons has previously been shown to be increased by phencyclidine, these data suggest that phencyclidine results in a differential regulation of presynaptic release of dopamine in mesolimbic/cortical as opposed to nigrostriatal dopaminergic regions.

Body mass index is different in normal Chinese and Caucasian infants.

Body mass index (BMI) is one of the anthropometric measurements for assessing nutritional status, body composition and adiposity in children. Racial differences in BMI between black and white children and adolescents have been shown in several studies. The aim of this study was to determine whether an ethnic difference in BMI exists between Chinese and Caucasian children in the first two years of life. The BMI of Chinese and Caucasian infants was compared so as to assess the usefulness of the National Center for Health Statistics (NCHS) growth reference data in the assessment of nutritional status of Chinese children. Mean weight, length and BMI were compared between six cohorts of Chinese children and five cohorts of Caucasian children together with the NCHS growth reference data. The changes in the mean BMI curves during the first two years of life in the two ethnic groups were entirely different but the different cohorts in the same ethnic groups displayed a similar pattern of change with age. The difference in change in BMI in the Chinese cohorts was related to the difference in change in their mean weight as compared to the NCHS weight-for-age reference data. In contrast, the change in mean length of the well-nourished Hong Kong Chinese children in the present study followed the mean NCHS height-for-age values. The results of this study suggest that linear growth would be better for the assessment of health and nutrition in infancy and early childhood. If BMI and weight-for-height standards were to be used then an ethnic group-specific and population based reference data set should be used.

Obstructive lung disease does not increase lung cancer mortality among female never-smokers in Hong Kong.

SETTING: High lung cancer mortality is observed among female never-smokers in Hong Kong. OBJECTIVE: To examine the relationship between obstructive lung disease (chronic obstructive pulmonary disease and/or asthma) and lung cancer mortality by sex and smoking status. DESIGN: A cohort of elderly clients (aged ≥65 years) in a health maintenance programme were followed prospectively through linkage with the territory-wide death registry for causes of death, using identity card number as the unique identifier. RESULTS: After 516,055 person-years of follow-up, respectively 1297, 872 and 1908 deaths were caused by lung cancer, other tobacco-related malignancies and non-tobacco-related malignancies. In the overall analysis, obstructive lung disease was independently associated with mortality due to lung cancer (aHR 1.86, P < 0.001) after adjustment for potential confounders. However, no association was detected among female never-smokers (HR 0.97, P = 0.909), in sharp contrast with female ever-smokers, male never-smokers and male ever-smokers (HR 1.98, 2.34 and 2.09, respectively, P from 0.047 to <0.001). Consistent results were observed after exclusion of all deaths in the initial 3 years. CONCLUSION: Obstructive lung disease exerted differential effects on lung cancer mortality across different sex and smoking subgroups in this Asian population, with a conspicuous absence of effect among female never-smokers.

Bicyclic and tricyclic thiophenes as protein tyrosine phosphatase 1B inhibitors.

A novel pyridothiophene inhibitor of PTP1B was discovered by rational screening of phosphotyrosine mimics at high micromolar concentrations. The potency of this lead compound has been improved significantly by medicinal chemistry guided by X-ray crystallography and molecular modeling. Excellent consistency has been observed between structure-activity relationships and structural information from PTP1B-inhibitor complexes.

Metallic contamination in oyster and other seafood in Hong Kong.

Heavy metal contamination in seafood is of great concern in places suffering from pollution. A survey has been carried out since 1986 to monitor the contents of seven heavy metals: antimony, arsenic, cadmium, chromium, lead, mercury and tin in oyster and other types of seafood. The daily intakes were estimated and compared to the Provisional Tolerable Weekly Intake (PTWI) or maximum acceptable daily load recommended by FAO/WHO Expert Committee on Food Additives (1984). In general, the levels were low and left comfortable margins to both the acceptable limits and the local regulatory levels with the exception of arsenic, the average intake of which was close to the PTWI.

Modulation of mesoprefrontal dopamine neurons by central benzodiazepine receptors. I. Pharmacological characterization.

The benzodiazepine (BZ) recognition sites on the gamma-aminobutyric acid receptor/chloride ionophore complex have been suggested to be involved in the modulation of mesoprefrontal dopamine (DA) neurons. We have examined further the effects of different classes of BZ receptor ligands on DA metabolism in the prefrontal cortex. The anxiogenic inverse agonist FG 7142 elevated selectively 3,4-dihydroxyphenylacetic acid (DOPAC) levels and DO-PAC/DA ratio in the prefrontal cortex in a dose- and time-dependent manner. The activating effect was not, however, observed in any other mesocortical, mesolimbic or nigrostriatal DA terminal fields examined. Pretreatments with BZ agonists such as diazepam, flurazepam, lorazepam and CGS 9896 and BZ antagonists such as Ro15-1788 and CGS 8216 and barbiturates such as pentobarbital, significantly antagonized the beta-carboline-induced elevation of prefrontal DOPAC levels. Furthermore, a significant correlation was found between the pharmacological profile of different BZ receptor ligands on prefrontal DA metabolism and their profiles in behavioral, electrophysiological and receptor binding studies. Agonists increased DA levels and consequently decreased DOPAC/DA ratio in the prefrontal cortex. Inverse agonists, on the other hand, significantly elevated prefrontal DOPAC levels and DOPAC/DA ratio in a dose-dependent manner. Antagonists such as Ro15-1788 and CGS 8216, at low doses, did not alter mesoprefrontal DA metabolism, but at higher doses did elevate DOPAC/DA ratio in the prefrontal cortex.(ABSTRACT TRUNCATED AT 250 WORDS)

Distinct patterns of early response gene expression and proliferation in mouse mast cells stimulated by stem cell factor, interleukin-3, or IgE and antigen.

Stem cell factor (SCF) is encoded at the Sl locus of the mouse and is the ligand for the c-kit receptor. Recombinant rat SCF164 (rrSCF164) induces proliferation and promotes maturation of mouse mast cells in vitro and in vivo and can also induce c-kit receptor-dependent mouse mast cell degranulation. We now report that in both quiescent and non-quiescent mouse bone marrow-derived cultured mast cells (BMCMC) rrSCF164 induces increased mRNA levels for the "early response genes" c-fos, c-jun and junB but has only slight effects on the expression of junD. Recombinant mouse interleukin-3 (IL-3) also promotes proliferation of both quiescent and non-quiescent BMCMC. However, IL-3 induces increased expression of c-fos and junB only in quiescent BMCMC. Cross-linking of Fc epsilon receptor type I (Fc epsilon RI) on BMCMC by IgE and specific antigen induces a pattern of early gene expression very similar to that induced by rrSCF164. However, BMCMC stimulated through the Fc epsilon RI did not proliferate and, in comparison to control BMCMC, exhibited significantly decreased proliferation in response to rrSCF164 or IL-3. These results indicate that stimulation of BMCMC proliferation by IL-3 or rrSCF164 induces distinct patterns of early response gene expression and suggest that the proliferative effects of these growth factors may be mediated through distinct signal transduction pathways. Our data also point to previously unappreciated similarities between the effects of signaling through the c-kit receptor or the Fc epsilon RI on mast cell expression of fos and jun genes.

Inlet and intrachamber concentration distributions in tracer studies of the canine central circulation and their relation to the isotope dilution residue function.

We analyzed the isotope dilution residue function from a single cardiac chamber for an arbitrary inlet distribution of tracer and arbitrary mixing within the chamber, and established a general relationship between cardiac output and the chamber residue function. In our experiments, we made simultaneous temperature measurements in three left ventricular chamber subregions of the dog subjected to left and right atrial injections of chilled saline. Flow-proportional tracer labeling always occurred at the left ventricular inlet when injection was into the right atrium. This state almost never obtained, however, with direct left atrial injection, although it was approximated most closely when multiple side hole cathers were used. We also demonstrated that imperfect tracer mixing in the normal ventricle can lead to significant regional temperature inequalities during tracer passage. These inequalities are more pronounced in the ventricle with compromised function, but in both normal and compromised ventricles they are minimal several beats after tracer concentration peaks if injection is into the right atrium.

Regulation of mouse and human mast cell development, survival and function by stem cell factor, the ligand for the c-kit receptor.

Stem cell factor (SCF), the ligand for the receptor (SCFR) that is encoded by the c-kit proto-oncogene, has many important effects in mouse and human mast cell development, survival, and function. SCF can promote mast cell survival by suppressing apoptosis, induce mast cell hyperplasia in murine rodents, experimental primates and humans, directly induce SCFR-dependent mast cell mediator release, and significantly modulate the extent of mast cell activation by Fc epsilon RI-dependent mechanisms. These findings raise several clinical issues and, in some cases, point to potentially significant therapeutic opportunities.

Detection of mouse mast cell-associated protease mRNA. Heparinase treatment greatly improves RT-PCR of tissues containing mast cell heparin.

The reverse transcriptase polymerase chain reaction (RT-PCR) procedure is markedly inhibited in specimens of blood that contain commercial heparin as an anticoagulant or in cell preparations containing rat or mouse peritoneal mast cells. However, it was not known whether the levels of endogenous, mast cell-associated heparin that are present in some mammalian tissues are sufficient to interfere with the use of RT-PCR in these settings. We show that RT-PCR detects little or no mRNA transcripts for either mast cell-associated products, such as mouse mast cell-associated protease-2 or -4 (MMCP-2 or MMCP-4) or mast cell carboxypeptidase A, or for mast cell-nonspecific products, such as glyceraldehyde 3-phosphate dehydrogenase, in routinely prepared specimens of cells or tissues that include populations of heparin-containing mast cells. However, signals for mast cell-associated or mast cell-nonspecific transcripts can be readily detected in such specimens if they are treated with heparinase before RT-PCR. RT-PCR after heparinase treatment appears to represent an extremely sensitive method for detecting mast cell-associated transcripts in tissue specimens, permitting the identification of transcripts for mast cell-specific proteases in the skin of genetically mast cell-deficient WBB6F1-W/WV mice, a tissue that contains few or no mast cells according to histological analysis.