Performance of the World Health Organisation suspected COVID-19 case definition in cluster-associated and sporadic SARS-CoV-2 transmission in Malaysia.

INTRODUCTION: Cluster-associated transmission has contributed to the majority of COVID-19 cases in Malaysia. Although widely used, the performance of the World Health Organization (WHO) case definition for suspected COVID19 in environments with high numbers of such cases has not been reported. MATERIALS AND METHODS: All suspected cases of COVID-19 that self-presented to hospitals or were cluster screened from 1st April to 31st May 2020 were included. Positive SARS-CoV-2 rRT-PCR was used as the diagnostic reference for COVID-19. RESULTS: 540 individuals with suspected COVID-19 were recruited. Two-third of patients were identified through contact screening, while the rest presented sporadically. Overall COVID-19 positivity rate was 59.4% (321/540) which was higher in the cluster screened group (85.6% vs. 11.6%, p<0.001). Overall, cluster-screened COVID-19 cases were significantly younger, had fewer comorbidities and were less likely to be symptomatic than those present sporadically. Mortality was significantly lower in the cluster-screened COVID-19 cases (0.3% vs. 4.5%, p<0.05). A third of all chest radiographs in confirmed COVID-19 cases were abnormal, with consolidation, ground-glass opacities or both predominating in the peripheral lower zones. The WHO suspected case definition for COVID-19 accurately classified 35.4% of all COVID-19 patients, a rate not improved by the addition of baseline radiographic data. Misclassification rate was higher among the cluster-associated cases (80.6%) compared to sporadic cases (35.3%). CONCLUSION: COVID-19 cases in Malaysia identified by active tracing of community cluster outbreaks had lower mortality rate. The WHO suspected COVID-19 performed poorly in this setting even when chest radiographic information was available, a finding that has implications for future spikes of the disease in countries with similar transmission characteristics.

Human VEGF165-myoblasts produce concomitant angiogenesis/myogenesis in the regenerative heart.

Bioengineering the regenerative heart may provide a novel treatment for heart failure. On May 14, 2002, a 55-year-old man suffering from ischemic myocardial infarction received 25 injections carrying 465 million cGMP-produced pure myoblasts into his myocardium after coronary artery bypass grafting. As on August 28, 2002, his EKG was normal and showed no arrhythmia. His ejection fraction increased by 13%. He no longer experienced shortness of breath and angina as he did before the treatment. Three myogenesis mechanisms were elucidated with 17 human/porcine xenografts using cyclosporine as immunosuppressant. Some myoblasts developed to become cardiomyocytes. Others transferred their nuclei into host cardiomyocytes through natural cell fusion. As yet others formed skeletal myofibers with satellite cells. De novo production of contractile filaments augmented the heart contractility. Human myoblasts transduced with VEGF165 gene produced six times more capillaries in porcine myocardium than in placebo. Xenograft rejection was not observed for up to 20 weeks despite cyclosporine discontinuation at 6 weeks. Pros and cons of autografts vs. allografts are compared to guide future development of heart cell therapy.

Attenuation of bleomycin induced pulmonary fibrosis in mice using the heme oxygenase inhibitor Zn-deuteroporphyrin IX-2,4-bisethylene glycol.

BACKGROUND: Pulmonary fibrosis is associated with a poor prognosis. The pathogenesis of fibrotic lung disorders remains unclear, but the extent of tissue damage due to the persistent presence of oxidants or proteases is believed to be important. The heme degrading enzyme heme oxygenase (HO) has been found to be expressed in experimental fibrosis, and generation of free iron and carbon monoxide (CO) by HO has been implicated in oxidant induced lung damage. A study was undertaken to examine the effects of the HO inhibitor Zn-deuteroporphyrin-IX-2,4-bisethylene glycol (Zndtp) on the development of pulmonary fibrosis in the bleomycin model of lung injury and repair. METHODS: Zndtp (10 micro mol/kg) was administered subcutaneously twice daily to mice 1 week following the intratracheal instillation of 0.025 U bleomycin. Animals were killed 10 or 21 days after bleomycin instillation and indices of lung damage and fibrosis were evaluated. RESULTS: Bleomycin treatment induced pulmonary cytotoxicity, increased levels of active transforming growth factor beta (TGF-beta), enhanced lung collagen accumulation, and decreased glutathione content. Zndtp administration significantly attenuated these indices. CONCLUSIONS: Administration of Zndtp in the bleomycin model resulted in appreciable alveolar cytoprotection and amelioration of pulmonary fibrosis. This molecule and its analogues may warrant further consideration in the treatment of acute lung injury and fibrotic lung disorders.

Human VEGF165-myoblasts produce concomitant angiogenesis/myogenesis in the regenerative heart.

Bioengineering the regenerative heart may provide a novel treatment for heart failure. On May 14, 2002, a 55-year-old man suffering from ischemic myocardial infarction received 25 injections carrying 465 million cGMP-produced pure myoblasts into his myocardium after coronary artery bypass grafting. As on August 28, 2002, his EKG was normal and showed no arrhythmia. His ejection fraction increased by 13%. He no longer experienced shortness of breath and angina as he did before the treatment. Three myogenesis mechanisms were elucidated with 17 human/porcine xenografts using cyclosporine as immunosuppressant. Some myoblasts developed to become cardiomyocytes. Others transferred their nuclei into host cardiomyocytes through natural cell fusion. As yet others formed skeletal myofibers with satellite cells. De novo production of contractile filaments augmented the heart contractility. Human myoblasts transduced with VEGF165 gene produced six times more capillaries in porcine myocardium than in placebo. Xenograft rejection was not observed for up to 20 weeks despite cyclosporine discontinuation at 6 weeks. Pros and cons of autografts vs. allografts are compared to guide future development of heart cell therapy. (Mol Cell Biochem 263: 173-178, 2004).

The pathology of systemic iridoviral disease in fish.

Iridoviruses have been associated with severe disease and economic loss in farmed food fish and ornamental fish, with mortality often reported to reach 50% or more. In the present study, three tropical marine food fish species and four tropical freshwater ornamental fish species with systemic iridovirus infections were examined histopathologically and ultrastructurally. Light microscopy consistently revealed pale to intensely basophilic hypertrophied virus-infected cells in spleen, kidney and intestine from all seven species. Ultrastructural examination showed changes in the vascular endothelium overlying hypertrophied virus-infected cells suggestive of pressure necrosis. Viral isolation was improved by the use of fibroblastic cell lines. This, together with the sub-endothelial location of infected cells in all infected species examined, suggests that systemic iridoviruses are mesotheliotropic.

Nature of codes extracted during the attentional blink.

This set of 6 experiments used a 2-target rapid serial visual presentation paradigm to address 2 main questions: (a) What is the nature of the code retrieved from nontarget (i.e., unselected) items? and (b) How do the processing demands of the target affect the nature of the codes extracted from its proximate distractors? There were 3 main results: First, unless a nontarget receives attentional processing, its codes remain dormant. The type of activated codes depends on the perceptual load imposed by the other items that also underwent processing. Second, the item trailing the target invariably gets processed, but those farther downstream are excluded. If target selection is exacting, the codes of the item leading the target may also be enhanced. Third, the magnitude of the attentional blink increases with target selection difficulty; it is, however, unaffected by the perceptual load imposed by the target.

Event-specific versus unitary causal accounts of optimism bias.

Optimism bias is often assumed to have a unitary cause regardless of the event, however, factors causing it may actually be event-specific. In Experiment 1 (N = 23), subjects rated the importance of various causes for individual events. The results identified consistent differences in perceptions of causal factors across events. Experiment 2 (N = 190) employed the possible causal factors absent/exempt error and degree of motivation to investigate an event-specific theory of optimism bias in a manipulation design. Participants were encouraged to view one causal factor (absent/exempt or motivation) as either important or unimportant to future risk when they estimated their risk of absent/exempt-related, motivation-related and unrelated events (as determined in Experiment 1). A hanging control group received no manipulation. The event-specific theory's prediction that these manipulations would affect particular events and not others were not supported. However, discouraging the absent/exempt error reduced optimism bias across events, generally. Hence, a unitary and not an event-specific theory of optimism bias was supported. Furthermore, for the first time, the possible role of and confounding of cognitive manipulations of optimism bias by mood were evaluated, and not supported.

Intracellular responses of productive hybridomas subjected to high osmotic pressure.

It has previously been found that hybridoma cells under hyperosmotic stress produce higher amounts of antibody. This study identified the cellular processes and mechanisms that occur during this event. In studies of hybridomas adapted to osmolarities ranging between 300 and 450 mOsm (using NaCI), antibody production increased to a saturation level while cell growth decreased progressively. At 500 mOsm, lower cell numbers and markedly decreased productivity resulted. Sucrose and KCI were found to induce similar trends, except to different extents. Several important changes in cellular responses were observed. Elevation of osmolarity with NaCl from 300 to 350 mOsm causes an increase of zwitterionic amino acid uptake, which occurred via Na+-dependent transport systems. In particular, system A was enhanced by 1.86-fold, but no enhancement was observed for Na+- independent transport systems. In addition, amino acids reactive with Na +-dependent transport systems were observed to be abundant within osmotically stressed hybridomas in the middle and late exponential stages. Sucrose and KCI caused similar uptake effects, but to a lesser degree, as long as sodium ions were present in solution. Specific consumption rates of glucose and glutamine increase by 19% and 20%. respectively, under high osmolarity treatment. These increases were confirmed by the 5% to 10% increase in cellular metabolic activity. At 350 mOsm, growth rate was slower compared with the 300-mOsm culture, which was reflected by the lower DNA concentration. Stressed cultures contained enhanced levels of total RNA, of which -80% is ribosomal RNA (rRNA). Higher rRNA content could in turn increase the translation rates of proteins. This was reflected in the accumulation of both dry cell weight and total cellular protein at linear rates of 0.42 pg/106 cells/mOsm and 0.21 pg/106 cells/mOsm, respectively, with increasing osmolarity between 300 and 450 mOsm. Overall, hybridomas increased their metabolic activities and amino acids uptake via the Na+-dependent symports to compensate for the osmotically elevated external environment. These effects contribute directly and indirectly to the increased cell mass consisting of a larger pool of amino acids, RNA, cellular proteins, and secreted antibody product

Suppression of valid inferences: syntactic views, mental models, and relative salience.

Byrne (1989) has demonstrated that although subjects can make deductively valid inferences of the modus ponens and modus tollens forms, these valid inferences can be suppressed by presenting an appropriate additional premise "If R then Q" with the original conditional "If P then Q". This suppression effect challenges the assumption of all syntactic theories of conditional reasoning that formal rules of inference such as modus ponens is part of mental logic. This paper argues that both the syntactic and the mental model accounts of the suppression effect are inadequate because they fail to give a principled account of the critical interpretive component involved in reasoning. In contrast, the relative salience model proposed in this study emphasized the centrality of the interpretative processes with the critical component being the relative salience of premises as judged by subjects on the basis of their prior knowledge activated in particular problem situations. Using 120 undergraduates and 120 policemen as subjects, predictions from the model were tested and confirmed in a suppression paradigm and evidence of convergent validity for the construct of salience were obtained. The results cannot be reconciled with either the syntactic view or the mental model view that have dominated theories of conditional reasoning.

Hyper-stimulation of monoclonal antibody production by high osmolarity stress in eRDF medium.

An earlier study (Chua et al., 1994) showed that hybridoma 2HG11 cultivated in a basal medium called eRDF, which is enriched in amino acids, enabled higher immunoglobulin (Ig) production with and without serum, when compared to two other traditional media RPMI and DMEM/F12. A further enhancement of Ig productivity was achieved when the osmolarity of the culture medium was increased from 300 mOsm to 350 mOsm (Oh et al., 1993). To determine whether the eRDF media was indeed better, three other cell lines, two IgG producers (TB/C3 and I13/17) and an IgM producer (B10), were tested. The results showed that maximum viable cell densities in eRDF medium were up to 3-times higher than in RPMI and maximum Ig titres were 2-8-times higher than in DMEM/F12 and RPMI. The three cell lines were similarly subjected to osmotic increases from 300 mOsm to 350 and 400 mOsm by addition of NaCl. There was an increase in Ig titres of between 30% to 100% compared to the control medium, although cell growth was reduced. Thus, hyper-stimulation by osmolarity stress was found to be generally effective in eliciting higher Ig production; the extent of enhancement being more pronounced for certain cell lines. Other osmolytes such as sucrose and KCl demonstrated similar effects of increasing Ig productivity. Study on the mechanism of action of osmotic stress on hybridoma 2HG11 revealed that hyper-stimulation of Ig productivity was fundamentally related to a greater availability of amino acids to cells as the cells actively accumulated more salt and amino acids to compensate for the higher medium osmolarity. Uptake of the amino acid analogues 14C-aminoisobutyric acid and 3H-methylaminoisobutyric acid into cells increased to 2.34 x 10(3) cpm per cell per min and 6.35 x 10(3) cpm per cell per min, respectively, under osmotic stress. This corresponds to an 85% increase in uptake via the Na(+)-dependent symport and a 50% increase in uptake via the Na(+)-independent and Na(+)-dependent symports. In the 350 mOsm medium, hybridomas also demonstrated an increase in metabolic activities of 5-10% compared to the control. This, together with the reduced specific growth rate in cells under osmotic stress, suggests that more energy was channelled into the biosynthetic pathway of Ig production.

Enhanced IgG production in eRDF media with and without serum. A comparative study.

The performance of three basal media RPMI, DMEM/F12 (DF) and eRDF (enhanced RDF, RPMI:DMEM:F12 in 2:1:1) were evaluated in cultures with and without serum with respect to cell proliferation, metabolism and monoclonal antibody (Mab) productivity. Based on the ease of adaptation, growth rate, maximum cell density and Mab production, the media were ranked as follows: eRDF > DF > RPMI. This was true for serum-free (SF) and serum supplemented (SS) media in static and shaker cultures. Growth performances in static and shaker cultures were consistently 20-50% lower in all three SF media compared to the corresponding SS conditions. Antibody titres in DF/SF and RPMI/SF cultures, irrespective of the culture condition, were generally similar or slightly lower than their SS counterparts. However, eRDF/SF medium yielded a much higher Mab titre (193 mg l-1) compared to eRDF/SS medium (145 mg l-1). This was also six times higher than the lowest titre of 30 mg l-1 in RPMI/SF medium. Hybridomas in eRDF/SF were further adapted to media without bovine serum albumin (eRDF/SF-BSA). Maximum cell densities in these cultures improved with scale up, from 1.1 x 10(6) ml-1 in static, to 1.9 x 10(6) ml-1 in shaker flasks, to 2.5 x 10(6) ml-1 in bioreactors. However, Ig levels remained between 100-130 mg l-1 which were much lower than in eRDF/SF medium. Thus BSA appears to be necessary for Ig production. The manufacturing cost (excluding purification) of Ig using eRDF was calculated to be between 17-50% of the price of the other two media and therefore this is regarded as the best medium for Ig production.

Substantial overproduction of antibodies by applying osmotic pressure and sodium butyrate.

Much of the current cell technology has enabled increased antibody production levels due to judicious nutrient feeding to raise cell densities and design better bioreactors. This study demonstrates that hybridomas can be hyperstimulated to produce higher immunoglobulin (lg) levels by suppressing cell growth and increasing culture longevity through adaptation to higher osmolarity media and addition of sodium butyrate. Prior to adaptation, cells placed in higher osmotic pressures (350 and 400 mOsm) were severely suppressed in growth down to 25% of the control (300 mOsm), although total lg titers achieved were similar to the control, approximately 140 mg/L. After a week of adaptation to 350 and 400 mOsm media, cell growth was not as dramatically suppressed, but considerably higher lg levels were attained at these elevated osmolarities. The highest yield of 265 mg/L was obtained at 350 mOsm compared to 140 mg/L at 300 mOsm, while maximum viable cell numbers dropped from 35 x 10(5) cells/mL to 31 x 10(5) cells/mL and culture longevity was extended by 20 h more than the control. Sodium butyrate, known to enhance protein production in other cell types, was then supplemented at a range of concentrations between 0.01 and 0.4 mM to the 350 mOsm culture to further enhance the lg levels. Butyrate at a concentration of 0.1 mM, in combination with osmotic pressure at 350 mOsm, further elevated the lg levels to 350 mg/L. Concomitantly, maximum viable cell numbers were reduced to 22 x 10(5) cells/mL, but culture longevity was extended by 40 h in the 0.1 mM butyrate supplemented culture compared to the control condition. Specific antibody productivity, q(Mab), continued to stay high during the stationary phase and was further elevated during the decline phase: thus, overall lg levels can be increased by 2.3 times by combining osmotic pressure and butyrate treatment.

A human colon cancer cell line established from collagen matrix cultures transplanted into nude mice.

A new human colon cancer cell line (020588) has been derived by means of a combined in vitro matrix-in vivo xenograft technique. The tumour cell line is carcino-embryonic antigen positive, displays a marker chromosome and proliferates in chemically-defined serum-free culture medium. The chemosensitivity pattern for the tumour cell line was similar to that observed for the parent tumour cells. The novel method used to establish this continuous human tumour cell line may have several advantages over standard techniques.

The role of colon fibroblasts in malignant large bowel obstruction--an experimental in vitro model.

The mechanism of bowel obstruction in colorectal cancer is likely to involve interactions between tumour cells, host fibroblasts and the extracellular matrix. The role of fibroblast-mediated matrix reorganisation in malignant structures of the large bowel was examined in an in vitro collagen matrix model in which tumour cells and fibroblasts were cultured under serum-free conditions. Colon cancer cells secreted a factor(s) which enhanced the ability of colon fibroblasts to contrast a collagen matrix without an associated mitogenic response by the fibroblasts. Within uncontracted collagen gels marked elongation of fibroblast cell processes was observed in the presence of the tumour-derived factor(s). We propose that matrix reorganisation by host fibroblasts in the wall of the human colon is responsible, at least in part, for malignant large bowel obstruction.

The processing of spatial frequency and orientation information.

Three identification experiments were completed to disambiguate the associations between spatial frequency and orientation information at the sensory, decisional, and response levels. The stimuli were gratings generated by crossing four levels each of spatial frequency and orientation. In Experiment 1, the subjects made a single identification response to the stimuli. In Experiment 2, two identification responses were made, one for the spatial frequency component and the other for the orientation component. In Experiment 3, the subjects identified either the spatial frequency or the orientation component in any block of trials. The data were confusion matrices, and an information-transmission approach was used to investigate the interactions in the system. The results show that although there were sensory associations, there were no interactions at the decisional level. Performance parity was found: there was no significant difference between the single- and double-judgment paradigms in terms of information transmitted. Overall, the results suggest that although spatial frequency and orientation information is coded jointly at the sensory level, subsequent processing is independent, with each dimension drawing upon different attentional resources.