Essential role of the mitochondrial apoptosis-inducing factor in programmed cell death

Programmed cell death is a fundamental requirement for embryogenesis, organ metamorphosis and tissue homeostasis. In mammals, release of mitochondrial cytochrome c leads to the cytosolic assembly of the apoptosome-a caspase activation complex involving Apaf1 and caspase-9 that induces hallmarks of apoptosis. There are, however, mitochondrially regulated cell death pathways that are independent of Apaf1/caspase-9. We have previously cloned a molecule associated with programmed cell death called apoptosis-inducing factor (AIF). Like cytochrome c, AIF is localized to mitochondria and released in response to death stimuli. Here we show that genetic inactivation of AIF renders embryonic stem cells resistant to cell death after serum deprivation. Moreover, AIF is essential for programmed cell death during cavitation of embryoid bodies-the very first wave of cell death indispensable for mouse morphogenesis. AIF-dependent cell death displays structural features of apoptosis, and can be genetically uncoupled from Apaf1 and caspase-9 expression. Our data provide genetic evidence for a caspase-independent pathway of programmed cell death that controls early morphogenesis.

Contact Tracing Assessment of COVID-19 Transmission Dynamics in Taiwan and Risk at Different Exposure Periods Before and After Symptom Onset

IMPORTANCE

The dynamics of coronavirus disease 2019 (COVID-19) transmissibility are yet to be fully understood. Better understanding of the transmission dynamics is important for the development and evaluation of effective control policies.

OBJECTIVE

To delineate the transmission dynamics of COVID-19 and evaluate the transmission risk at different exposure window periods before and after symptom onset.

DESIGN, SETTING, AND PARTICIPANTS

This prospective case-ascertained study in Taiwan included laboratory-confirmed cases of COVID-19 and their contacts. The study period was from January 15 to March 18, 2020. All close contacts were quarantined at home for 14 days after their last exposure to the index case. During the quarantine period, any relevant symptoms (fever, cough, or other respiratory symptoms) of contacts triggered a COVID-19 test. The final follow-up date was April 2, 2020.

MAIN OUTCOMES AND MEASURES

Secondary clinical attack rate (considering symptomatic cases only) for different exposure time windows of the index cases and for different exposure settings (such as household, family, and health care).

RESULTS

We enrolled 100 confirmed patients, with a median age of 44 years (range, 11-88 years), including 44 men and 56 women. Among their 2761 close contacts, there were 22 paired index-secondary cases. The overall secondary clinical attack rate was 0.7% (95% CI, 0.4%-1.0%). The attack rate was higher among the 1818 contacts whose exposure to index cases started within 5 days of symptom onset (1.0% [95% CI, 0.6%-1.6%]) compared with those who were exposed later (0 cases from 852 contacts; 95% CI, 0%-0.4%). The 299 contacts with exclusive presymptomatic exposures were also at risk (attack rate, 0.7% [95% CI, 0.2%-2.4%]). The attack rate was higher among household (4.6% [95% CI, 2.3%-9.3%]) and nonhousehold (5.3% [95% CI, 2.1%-12.8%]) family contacts than that in health care or other settings. The attack rates were higher among those aged 40 to 59 years (1.1% [95% CI, 0.6%-2.1%]) and those aged 60 years and older (0.9% [95% CI, 0.3%-2.6%]).

CONCLUSIONS AND RELEVANCE

In this study, high transmissibility of COVID-19 before and immediately after symptom onset suggests that finding and isolating symptomatic patients alone may not suffice to contain the epidemic, and more generalized measures may be required, such as social distancing.

Analgesic and anti-inflammatory activities of [6]-gingerol

In the present study, the analgesic and anti-inflammatory effects of [6]-gingerol, which is the pungent constituent of ginger, were performed. Intraperitoneal administration of [6]-gingerol (25 mg/kg-50 mg/kg) produced an inhibition of acetic acid-induced writhing response and formalin-induced licking time in the late phase. [6]-Gingerol (50 mg/kg-100 mg/kg) also produced an inhibition of paw edema induced by carrageenin. These results suggested that [6]-gingerol possessed analgesic and anti-inflammatory activities.

Potential lessons from the Taiwan and New Zealand health responses to the COVID-19 pandemic

Approaches to preventing or mitigating the impact of the COVID-19 pandemic have varied markedly between nations. We examined the approach up to August 2020 taken by two jurisdictions which had successfully eliminated COVID-19 by this time: Taiwan and New Zealand. Taiwan reported a lower COVID-19 incidence rate (20.7 cases per million) compared with NZ (278.0 per million). Extensive public health infrastructure established in Taiwan pre-COVID-19 enabled a fast coordinated response, particularly in the domains of early screening, effective methods for isolation/quarantine, digital technologies for identifying potential cases and mass mask use. This timely and vigorous response allowed Taiwan to avoid the national lockdown used by New Zealand. Many of Taiwan's pandemic control components could potentially be adopted by other jurisdictions.

Gallic acid ameliorated impaired glucose and lipid homeostasis in high fat diet-induced NAFLD mice

Gallic acid (GA), a naturally abundant plant phenolic compound in vegetables and fruits, has been shown to have potent anti-oxidative and anti-obesity activity. However, the effects of GA on nonalcoholic fatty liver disease (NAFLD) are poorly understood. In this study, we investigated the beneficial effects of GA administration on nutritional hepatosteatosis model by a more “holistic view” approach, namely ¹H NMR-based metabolomics, in order to prove efficacy and to obtain information that might lead to a better understanding of the mode of action of GA. Male C57BL/6 mice were placed for 16 weeks on either a normal chow diet, a high fat diet (HFD, 60%), or a high fat diet supplemented with GA (50 and 100 mg/kg/day, orally). Liver histopathology and serum biochemical examinations indicated that the daily administration of GA protects against hepatic steatosis, obesity, hypercholesterolemia, and insulin resistance among the HFD-induced NAFLD mice. In addition, partial least squares discriminant analysis scores plots demonstrated that the cluster of HFD fed mice is clearly separated from the normal group mice plots, indicating that the metabolic characteristics of these two groups are distinctively different. Specifically, the GA-treated mice are located closer to the normal group of mice, indicating that the HFD-induced disturbances to the metabolic profile were partially reversed by GA treatment. Our results show that the hepatoprotective effect of GA occurs in part through a reversing of the HFD caused disturbances to a range of metabolic pathways, including lipid metabolism, glucose metabolism (glycolysis and gluconeogenesis), amino acids metabolism, choline metabolism and gut-microbiota-associated metabolism. Taken together, this study suggested that a ¹H NMR-based metabolomics approach is a useful platform for natural product functional evaluation. The selected metabolites are potentially useful as preventive action biomarkers and could also be used to help our further understanding of the effect of GA in hepatosteatosis mice.

Calcium-regulated DNA binding and oligomerization of the neuronal calcium-sensing protein, calsenilin/DREAM/KChIP3

Calsenilin/DREAM/KChIP3, a member of the recoverin branch of the EF-hand superfamily, interacts with presenilins, serves as a calcium-regulated transcriptional repressor, and interacts with A-type potassium channels. Here we report physicochemical characterization of calcium binding, oligomerization, and DNA binding of human calsenilin/DREAM/KChIP3. Equilibrium Ca(2+) binding measurements indicate that the protein binds 3 Ca(2+) with a dissociation constant of 14 microM and a Hill coefficient of 0.7. Dynamic light scattering and size exclusion chromatography show that the Ca(2+)-bound protein exists as a dimer at protein concentrations lower than 150 microM and forms a tetramer at concentrations above 200 microM. The Ca(2+)-free protein is a tetramer in the concentration range 20-450 microM. Isothermal titration calorimetry and dynamic light scattering indicate that the Ca(2+)-free protein tetramer binds endothermically (DeltaH = +25 kcal/mol) to four molecules of DNA derived from the downstream regulatory element (DRE) of either the prodynorphin or c-fos genes. One DRE molecule binds tightly to the protein with a dissociation constant (K(d)) of 75 nM, and the other three bind more weakly (K(d) = 640 nM). No significant DNA binding was observed for the Ca(2+)-bound protein. The N-terminal protein fragment (residues 1-70) binds nonspecifically to DRE in a Ca(2+)-independent manner, whereas a C-terminal fragment containing the four EF-hands (residues 65-256) binds DRE (K(d) = 200 nM) in a Ca(2+)-regulated and sequence-specific fashion. The C-terminal fragment is a tetramer in the Ca(2+)-free state and dissociates into dimers at saturating Ca(2+) levels.

Neuroprotective effects of phenyl-t-butyl-nitrone in gerbil global brain ischemia and in cultured rat cerebellar neurons

We examined the ability of phenyl-t-butyl-nitrone (PBN), an electron spin trapper, to attenuate ischemia-induced forebrain edema and hippocampal CA1 neuronal loss in gerbils, and to protect rat cerebellar neurons in primary culture from glutamate-induced toxicity. PBN, given i.p. at 75 or 150 mg/kg 30 min before ischemia (5 min occlusion), increased survival (at 7 days) of CA1 neurons from 60 +/- 14 (vehicle-treated, n = 17) to 95 +/- 15 (P less than 0.05, n = 15) and 145 +/- 3 (P less than 0.01, n = 15), respectively. When gerbils were treated with PBN (50 mg/kg, i.p.) immediately and 6 h after reperfusion, followed by b.i.d. for an additional 2 days, CA1 neurons survival improved from 35 +/- 9 (vehicle, n = 20, 6 min occlusion) to 106 +/- 17 (P less than 0.01, n = 13). In gerbils exposed to a more severe ischemia (10 min), pretreatment with 150 mg/kg PBN increased the survival of CA1 neurons from 6 +/- 6 (vehicle) to 27 +/- 10 (P less than 0.05, n = 11). Pretreatment with PBN, at 150 mg/kg, reduced forebrain edema (following 15 min ischemia) by 24.7% (P less than 0.01, n = 16). PBN at 50 mg/kg, i.p. had no hypothermic effect and at 75 or 150 mg/kg caused a transient hypothermia. The presence of PBN in the brain was confirmed in microdialysis samples and brain tissue extract using HPLC. In vitro, PBN protected rat cerebellar neurons against 100 microM glutamate-induced toxicity with an EC50 value of 2.7 mM. Our results further support the concept that free radicals contribute to brain injury following ischemia and suggest the potential therapeutic application of electron spin trappers in stroke.

Azepanone-based inhibitors of human and rat cathepsin K

The synthesis, in vitro activities, and pharmacokinetics of a series of azepanone-based inhibitors of the cysteine protease cathepsin K (EC 3.4.22.38) are described. These compounds show improved configurational stability of the C-4 diastereomeric center relative to the previously published five- and six-membered ring ketone-based inhibitor series. Studies in this series have led to the identification of 20, a potent, selective inhibitor of human cathepsin K (K(i) = 0.16 nM) as well as 24, a potent inhibitor of both human (K(i) = 0.0048 nM) and rat (K(i,app) = 4.8 nM) cathepsin K. Small-molecule X-ray crystallographic analysis of 20 established the C-4 S stereochemistry as being critical for potent inhibition and that unbound 20 adopted the expected equatorial conformation for the C-4 substituent. Molecular modeling studies predicted the higher energy axial orientation at C-4 of 20 when bound within the active site of cathepsin K, a feature subsequently confirmed by X-ray crystallography. Pharmacokinetic studies in the rat show 20 to be 42% orally bioavailable. Comparison of the transport of the cyclic and acyclic analogues through CaCo-2 cells suggests that oral bioavailability of the acyclic derivatives is limited by a P-glycoprotein-mediated efflux mechanism. It is concluded that the introduction of a conformational constraint has served the dual purpose of increasing inhibitor potency by locking in a bioactive conformation as well as locking out available conformations which may serve as substrates for enzyme systems that limit oral bioavailability.

Carvedilol, a new antihypertensive agent, prevents lipid peroxidation and oxidative injury to endothelial cells

The protective effects of carvedilol, a new beta-adrenergic receptor blocker and vasodilating antihypertensive agent, against oxygen free radical-mediated injury were studied in cultured bovine endothelial cells and compared with five other beta-blockers. Carvedilol dose-dependently inhibited oxygen radical-induced lipid peroxidation (50% inhibition at 2.6 mumol/L) and glutathione depletion (50% inhibition at 1.8 mumol/L) in the cells. Under the same conditions, other beta-blockers--propranolol, labetalol, pindolol, atenolol, and celiprolol--had only mild or no effect. Moreover, carvedilol protected against oxygen radical--mediated cell damage, as assessed by cellular lactate dehydrogenase release, with a 50% inhibition at 4.1 mumol/L and increased the cell survival in a dose-dependent manner, whereas other beta-blockers had mild or no effects. Pretreatment of the cells with carvedilol for 7 days significantly enhanced the protective effects of carvedilol. Using 2-methyl-2-nitrosopropane as a trapping agent, the spin adduct in cell lipids was monitored by electron paramagnetic resonance. Carvedilol dose-dependently decreased the intensity of the free radical signals, indicating its free radical-scavenging ability. The prevention of oxidative injury to endothelial cells might potentially contribute to the clinical beneficial effects of carvedilol as an antihypertensive agent.

Distribution of spin-trapping compounds in rat blood and brain: in vivo microdialysis determination

Microdialysis was utilized to determine blood and brain distribution of spin-trapping nitrone compounds in the rat following intraperitoneal administration. In vivo quantitation by high-pressure liquid chromatography (HPLC) analysis, in vitro calibration of microdialysis probes, optimum perfusion rate, and the relationship of microdialysis sample recovery to tissue levels were evaluated in detail. The microdialysis sampling and HPLC analysis provided on-line, within-animal pharmacokinetic time-course determinations. At equimolar concentrations, 150 mg/kg alpha-phenyl-N-tert-butyl nitrone (PBN) or 165 mg/kg alpha-4-pyridyl-N-oxide N-tert-butyl nitrone (POBN) reached a similar, steady-state venous blood concentration of 224 +/- 21 microM and 210 +/- 10 microM, respectively. The POBN steady-state brain concentration was 149 +/- 9 microM, a significantly (p < .05) lower concentration than in the blood. In contrast, the brain concentration of PBN was 331 +/- 25 microM, significantly (p < .05) higher than its concentration in the blood. The increased brain distribution/penetration of PBN was attributed to its greater lipophilicity as measured by its octanol/water partition coefficient. All microdialysis results were validated by direct measurement of blood and brain levels at steady-state using conventional extraction procedures and assays. Also, the amount of tissue/cell bound versus unbound nitrones was determined by comparing the microdialysis "dialyzable" fraction with the total amount from whole tissue extracts. These data demonstrate that on-line determinations of nitrone spin-trap brain penetration/levels can be carried out accurately using in vivo microdialysis. The implication of these results for potential use of the microdialysis technique for detection of free radical products in in vivo animal models is discussed.

Analgesic and anti-inflammatory activities of ethanol root extract of Mahonia oiwakensis in mice

AIMS OF THE STUDY

This study investigated the anti-inflammatory and analgesic activities, and protoberberine alkaloid contents of ethanol extract of MO roots (MOR(EtOH)).

MATERIALS AND METHODS

The analgesic activity of MOR(EtOH) was determined using acetic acid-induced writhing response and formalin test. The anti-inflammatory activity of MOR(EtOH) was determined using the lambda-carrageenan-induced paw oedema model. The protoberberine alkaloid contents of MOR(EtOH) were identified by high-performance liquid chromatography (HPLC).

RESULTS

MOR(EtOH) (100 and 500 mg/kg) decreased the acetic acid-induced writhing responses and licking times of the second phase in the formalin test. Moreover, carrageenan-induced paw oedema was significantly reduced in a dose-dependent manner by administering MOR(EtOH) (100 and 500 mg/kg) at 3, 4, and 5h after the carrageenan injection. The serum levels of tumor necrosis factor-alpha (TNF-alpha) and nitric oxide (NO) of MOR(EtOH)-treated mice were significantly reduced compared with those in the serum of animals administered carrageenan. Notably, MOR(EtOH) attenuated the expression of cyclo-oxygenase 2 (COX-2) and inducible nitric oxide synthase (iNOS) and neutrophil infiltration in paw tissues injected with carrageenan. The anti-inflammatory mechanisms of MOR(EtOH) appear to be related to the inhibition of neutrophil infiltration, iNOS and COX-2 protein expression, NO release, and the decreasing TNF-alpha level in serum. The analytical results showed that the contents of berberine, palmatine and jatrorrhizine were 191.45 mg/g extract, 100.15 mg/g extract and 66.45 mg/g extract, respectively.

CONCLUSION

These experimental results suggest that MOR(EtOH) produced both analgesic and anti-inflammatory effects in mice and may be a candidate for the development of pharmacological agents used in the treatment of inflammatory disorders.

Carvedilol-liposome interaction: evidence for strong association with the hydrophobic region of the lipid bilayers

Carvedilol (Kredex, Coreg) is a multiple action antihypertensive drug that has been shown to protect cell membranes from lipid peroxidative damages. In this study the physical and structural effects of carvedilol on lipid bilayers are investigated by fluorescence techniques, differential scanning calorimetry and other physical methods. Carvedilol binds to liposomal membranes (9:1 DMPC:DMPG) strongly with an apparent binding constant on the order of 10(4) M-1 in PBS (pH 7.4). The characteristic changes in its intrinsic fluorescence properties when bound to liposomes suggest that this compound is situated in a non-polar environment. The Stern-Volmer and bimolecular quenching constants, determined using nitrate as the fluorescence quencher, for the free and bound carvedilol indicate that the carbazole moiety is at a depth of > 11 A in the lipid bilayer. Fluorescence anisotropy measurements show that, unlike the membrane probes DPH and TMA-DPH, carvedilol is relatively mobile, and does not have a rigidly-defined molecular orientation in the bilayers. Differential scanning calorimetry results indicate that carvedilol is an effective membrane "fluidizer' as it dose-dependently lowers the gel to liquid crystalline transition temperature and broadens the endothermic transition. Comparative studies of interactions of carbazole, 4-OH carbazole and carvedilol with the model liposomal membranes reveal a possible role of membrane-partitioning in their antioxidant efficacy. These findings are discussed in perspective with the membrane biophysical properties of different classes of therapeutic significant lipid antioxidants in mind.

Carvedilol, a new vasodilating beta adrenoceptor blocker antihypertensive drug, protects endothelial cells from damage initiated by xanthine-xanthine oxidase and neutrophils

OBJECTIVE

Oxygen radical mediated endothelial injury plays an important role in cardiovascular disease. Carvedilol, a new beta blocker and antihypertensive agent, has been shown to have antioxidant activity. The aim of this study was to determine whether carvedilol protects oxygen radical induced endothelial injury.

METHODS

Cultured bovine pulmonary artery (BPAEC) and human umbilical vein endothelial cells (HUVEC) were used and oxygen radicals were generated by xanthine-xanthine oxidase or phorbol myristate acetate (PMA) activated human neutrophils. Cell injury was assessed by lactate dehydrogenase (LDH) release and cell death, or 51 Cr release from prelabelled BPAEC. The electron paramagnetic resonance (EPR) spin trapping technique was used to detect the amount of radical spin adducts formed in cell lipids.

RESULTS

Carvedilol dose dependently inhibited xanthine-xanthine oxidase induced LDH release from BPAEC and HUVEC, with IC50 values of 3.8 microM and 2.6 microM, respectively, and significantly reduced cell death by xanthine-xanthine oxidase. Other beta blockers tested (propranolol, labetalol, pindolol, and celiprolol) showed a mild effect or no effect at all. Increasing the time of pretreatment with carvedilol enhanced its cell protective effect against oxidative stress. Carvedilol also protected BPAEC dose dependently from PMA activated, neutrophil induced cell injury. Carvedilol had no effect on xanthine oxidase activity. EPR study confirmed that xanthine-xanthine oxidase induced the formation of lipid derived radicals in cell lipids and carvedilol scavenged free radicals, as indicated by the decreased EPR signal.

CONCLUSIONS

Carvedilol protects endothelial cells against oxygen radical mediated cell injury and death by scavenging free radicals. The prevention of oxidative injury to endothelial cells might potentially contribute to the clinical beneficial effects of carvedilol as an antihypertensive agent.

Hepatoprotective effect of Phyllanthus in Taiwan on acute liver damage induced by carbon tetrachloride

The effect of oral administration of Phyllanthus methanolic extracts (PME) (i.e. P. acidus, P. emblica, P. myrtifolius, P. multiflorus, P. amarus, P. debilis, P. embergeri, P. hookeri, P. tenellus, P. urinaria L.s. nudicarpus, P. urinaria L.s. urinaria) or gallic acid (GA) on the progression of acute liver damage induced by CCl(4) in rats was examined by morphological and biochemical methods. P. acidus, P. urinaria L.s. urinaria, GA at a dose of 0.5 g/kg, and P. emblica, P. urinaria L.s. nudicarpus at a dose of 1.0 g/kg attenuated CCl(4)-induced increase in serum glutamate-oxalate-transaminase (GOT). P. acidus, P. urinaria L.s. nudicarpus, P. urinaria L.s. urinaria, GA at a dose of 0.5 g/kg, and P. emblica, P. amarus, P. hookeri, P. tenellus at a dose of 1.0 g/kg attenuated CCl(4)-induced increase in serum glutamate-pyruvate-transaminase (GPT). Concurrently, P. acidus, P. multiflorus, P. embergeri, P. hookeri, P. tenellus and P. urinaria L.s. urinaria elevated the activity of liver reduced glutathione peroxidase (GSH-Px). Since the protective effects of P. acidus, P. emblica, P. myrtifolius, P. embergeri, P. urinaria L.s. nudicarpus, P. urinaria L.s. urinaria and GA correlate with a reduction in liver infiltration and focal necrosis observed using histological methods, these data demonstrate that P. acidus and P. urinaria L.s. urinaria are hepatoprotective and antioxidant agents.

Comparison of metoprolol and carvedilol pharmacology and cardioprotection in rabbit ischemia and reperfusion model

Carvedilol, a selective alpha1 and non-selective beta-adrenoceptor antagonist and antioxidant, has been shown to provide significant cardiac protection in animal models of myocardial ischemia. To further explore the mechanisms contributing to carvedilol cardioprotection efficacy, the effects of carvedilol on hemodynamic variables, infarct size and myeloperoxidase activity (an index of neutrophil accumulation) were compared with a beta1-selective adrenoceptor antagonist, metoprolol. Carvedilol (1 mg/kg) or metoprolol (1 mg/kg or 1 mg/kg + 0.5 mg/kg 90 min later) was given intravenously 5 min before reperfusion. In vehicle-treated rabbits, ischemia (60 min) and reperfusion (180 min) resulted in significant increments in left ventricular end diastolic pressure, large infarcts (59+/-2.6% of area-at-risk) and marked increase in myeloperoxidase activity (0.59+/-0.09 U/100 mg tissue). Carvedilol treatment resulted in sustained reduction of pressure-rate-index and significantly smaller infarcts (22.0+/-2.5%, P < 0.01 vs. vehicle) as well as decreased myeloperoxidase activity (0.186+/-0.056 U/100 mg tissue, P < 0.01 vs. vehicle). The highest dose of metoprolol, 1 mg/kg + 0.5 mg/kg, that resulted in pressure-rate-index comparable to that of 1.0 mg/kg carvedilol, failed to reduce myeloperoxidase activity in the ischemic myocardial tissue, and the infarct size (35+/-3.1%) was significantly larger than in carvedilol-treated animals. Taken together, this study suggests that the superior cardioprotection of carvedilol over metoprolol is not a consequence of hemodynamic variances but possibly the result of the additional pharmacological properties of carvedilol such as the antioxidant and anti-neutrophil effects.

Mean residence time concepts for pharmacokinetic systems with nonlinear drug elimination described by the Michaelis-Menten equation

Equations for the mean residence time (MRT) of drug in the body and related functions are derived for drugs which are intravenously administered into a one- or two-compartment system with Michaelis-Menten elimination. This MRT is a function of the steady-state volume of distribution and time-average clearance obtained from the dose and area under the curve (dose/AUC). The differences between the MRT calculated by the proposed method and by using the moment theory method (AUM/AUC) are demonstrated both mathematically and by computer simulations. The validity of the proposed method for calculation of MRT and its relationship to the moment theory results have also been assessed by examining the percentage of the administered dose eliminated and the percentage of the total area attained at MRT and at AUM/AUC in relation to the dose. The equations evolved should be helpful in clarifying residence time derivations and in defining the disposition characteristics and differences between linear and nonlinear systems. Direct methods are provided for calculation of Michaelis-Menten parameters based on the relationship between MRT and dose.

The correlation between the presence of viremia and clinical severity in patients with enterovirus 71 infection: a multi-center cohort study

BACKGROUND

Enterovirus 71 (EV71) is a great disease burden across the whole world, particularly in Southeast Asia. However, in recent decades, the pathogenesis of severe EV71 infection was not well understood. This study was aimed to investigate the correlation between the presence of viremia and the clinical severity of EV71 infection.

METHODS

We organized a prospective cohort study and enrolled laboratory-confirmed EV71 cases in six tertiary care hospitals in Taiwan during the EV71 epidemic from 2011 to 2012. Blood samples were collected once in the acute stage, on the first day of admission. We used real-time RT-PCR to detect EV71 viremia. Demographical and clinical data were collected and the clinical severity was categorized into four grades. Data analysis was performed to identify the risk factors of viremia and the correlation between viremia and clinical severity of EV71 infection.

RESULTS

Of the total 224 enrolled patients, 59 (26%) patients were confirmed to have viremia. Two-thirds (68%) of viremic cases were detected within the first three days of infection. Viremia occurred more frequently in children under the age of one year old (odds ratios [OR] 4.82, p < 0.001) but the association between the presence of viremia and complicated EV71 infection was not found (OR 1.02, p = 0.96). In the viremia group, patients had significantly more severe complications if viremia was detected after the third day of disease onset (26% vs. 5%, p = 0.03).

CONCLUSIONS

Viremia occurred more frequently in children under the age of one year and viremia detected beyond three days after the onset of disease correlated with more severe disease in EV71 patients.

The XbaI-BlnI-CeuI genomic cleavage map of Salmonella paratyphi B

The genomic cleavage map of Salmonella paratyphi B was determined through digestion with endonucleases and separation of the fragments by pulsed-field gel electrophoresis. The chromosome has 19 XbaI sites, 10 BlnI sites, and 7 CeuI sites. The fragments were arranged in order through excision of fragments from the gel, redigestion with a second enzyme, end labelling with 32P, and reelectrophoresis. Tn10 transposons inserted in 61 different genes of S. typhimurium LT2 were transduced by use of bacteriophage P22 into S. paratyphi B. The locations of Tn10 insertions on the chromosome of S. paratyphi B were determined by use of XbaI and BlnI sites in Tn10, revealing the positions of genes with Tn10 insertions in S. paratyphi B. All seven CeuI sites (in rrl genes for 23S rRNA) and most of the XbaI and BlnI sites in rrn genes for Glt-tRNA are conserved, but only about half of the XbaI and BlnI sites outside rrn genes are conserved. Gene order is identical in the 68 genes that we could compare between S. paratyphi B and S. typhimurium LT2, and the lengths of intervals between the genes are often the same, but there are several instances of differences in interval lengths, indicating that insertions or deletions of DNA have occurred during the evolutionary divergence of these bacteria.

Regulation of blood and vascular cell function by bioactive lysophospholipids

Lysophosphatidic acid (LPA), its sphingolipid homolog sphingosine 1-phosphate (S1P) and several other related molecules constitute a family of bioactive lipid phosphoric acids that function as receptor-active mediators with roles in cell growth, differentiation, inflammation, immunomodulation, apoptosis and development. LPA and S1P are present in physiologically relevant concentrations in the circulation. In isolated cell culture systems or animal models, these lipids exert a range of effects that suggest that S1P and LPA could play important roles in maintaining normal vascular homeostasis and in vascular injury responses. LPA and S1P act on a series of G protein-coupled receptors, and LPA may also be an endogenous regulator of PPARgamma activity. In this review, we discuss potential roles for lysolipid signaling in the vasculature and mechanisms by which these bioactive lipids could contribute to cardiovascular disease.

Comparison of Estimated Effectiveness of Case-Based and Population-Based Interventions on COVID-19 Containment in Taiwan

IMPORTANCE

Taiwan is one of the few countries with initial success in COVID-19 control without strict lockdown or school closure. The reasons remain to be fully elucidated.

OBJECTIVE

To compare and evaluate the effectiveness of case-based (including contact tracing and quarantine) and population-based (including social distancing and facial masking) interventions for COVID-19 in Taiwan.

DESIGN, SETTING, AND PARTICIPANTS

This comparative effectiveness study used a stochastic branching process model using COVID-19 epidemic data from Taiwan, an island nation of 23.6 million people, with no locally acquired cases of COVID-19 reported for 253 days between April and December 2020.

MAIN OUTCOMES AND MEASURES

Effective reproduction number of COVID-19 cases (the number of secondary cases generated by 1 primary case) and the probability of outbreak extinction (0 new cases within 20 generations). For model development and calibration, an estimation of the incubation period (interval from exposure to symptom onset), serial interval (time between symptom onset in an infector-infectee pair), and the statistical distribution of the number of any subsequent infections generated by 1 primary case was calculated.

RESULTS

This study analyzed data from 158 confirmed COVID-19 cases (median age, 45 years; interquartile range, 25-55 years; 84 men [53%]). An estimated 55% (95% credible interval [CrI], 41%-68%) of transmission events occurred during the presymptomatic stage. In our estimated analysis, case detection, contact tracing, and 14-day quarantine of close contacts (regardless of symptoms) was estimated to decrease the reproduction number from the counterfactual value of 2.50 to 1.53 (95% CrI, 1.50-1.57), which would not be sufficient for epidemic control, which requires a value of less than 1. In our estimated analysis, voluntary population-based interventions, if used alone, were estimated to have reduced the reproduction number to 1.30 (95% CrI, 1.03-1.58). Combined case-based and population-based interventions were estimated to reduce the reproduction number to below unity (0.85; 95% CrI, 0.78-0.89). Results were similar for additional analyses with influenza data and sensitivity analyses.

CONCLUSIONS AND RELEVANCE

In this comparative effectiveness research study, the combination of case-based and population-based interventions (with wide adherence) may explain the success of COVID-19 control in Taiwan in 2020. Either category of interventions alone would have been insufficient, even in a country with an effective public health system and comprehensive contact tracing program. Mitigating the COVID-19 pandemic requires the collaborative effort of public health professionals and the general public.

A point mutation in the N-terminal coiled-coil domain releases c-Fes tyrosine kinase activity and survival signaling in myeloid leukemia cells

The c-fes locus encodes a 93-kDa non-receptor protein tyrosine kinase (Fes) that regulates the growth and differentiation of hematopoietic and vascular endothelial cells. Unique to Fes is a long N-terminal sequence with two regions of strong homology to coiled-coil oligomerization domains. We introduced leucine-to-proline substitutions into the coiled coils that were predicted to disrupt the coiled-coil structure. The resulting mutant proteins, together with wild-type Fes, were fused to green fluorescent protein and expressed in Rat-2 fibroblasts. We observed that a point mutation in the first coiled-coil domain (L145P) dramatically increased Fes tyrosine kinase and transforming activities in this cell type. In contrast, a similar point mutation in the second coiled-coil motif (L334P) was without effect. However, combining the L334P and L145P mutations reduced transforming and kinase activities by approximately 50% relative to the levels of activity produced with the L145P mutation alone. To study the effects of the coiled-coil mutations in a biologically relevant context, we expressed the mutant proteins in the granulocyte-macrophage colony-stimulating factor (GM-CSF)-dependent myeloid leukemia cell line TF-1. In this cellular context, the L145P mutation induced GM-CSF independence, cell attachment, and spreading. These effects correlated with a marked increase in L145P protein autophosphorylation relative to that of wild-type Fes. In contrast, the double coiled-coil mutant protein showed greatly reduced kinase and biological activities in TF-1 cells. These data are consistent with a role for the first coiled coil in the negative regulation of kinase activity and a requirement for the second coiled coil in either oligomerization or recruitment of signaling partners. Gel filtration experiments showed that the unique N-terminal region interconverts between monomeric and oligomeric forms. Single point mutations favored oligomerization, while the double point mutant protein eluted essentially as the monomer. These data provide new evidence for coiled-coil-mediated regulation of c-Fes tyrosine kinase activity and signaling, a mechanism unique among tyrosine kinases.

Reactions of chloropromazine cation radical with physiologically occurring nucleophiles

The reactions between chlorpromazine cation radical and a variety of physiologically occurring nucleophiles, which involve formation of a covalent, yet reversible bond, have been examined. As reported earlier, this reaction does not involve disproportionation of the radical but, rather, direct reaction between radical and nucleophile. The resulting adduct further reacts to form chlorpromazine sulfoxide or hydroxylated derivatives, and the original nucleophile is regenerated. The products and kinetics of the reaction depend strongly on the identity of the nucleophile, with the sulfhydryl group being the fastest and water being the slowest of the nucleophiles studied. The likely involvement of these reactions in the metabolism of chlorpromazine is discussed. In addition, it is proposed that the radical/nucleophile interaction is a reasonable model reaction for the effects of chlorpromazine radical on neuronal enzymes and receptor sites.