Coronavirus COVID-19 outbreak and control: Effect of temperature, relative humidity, and lockdown implementation.

Meteorological parameters are important factors that have an influence on infectious diseases. The present study aimed to explore the correlation between the spread of COVID-19, temperature, and relative humidity. The effect of human-imposed control parameters in the form of lockdown on the dissipation of COVID-19 was also analysed. Data were collected on the three study variables - temperature, relative humidity, and lockdown period - from nine of the most infected cities worldwide as well as information on changes in the number of COVID-19 patients from the beginning to a specific point in the lockdown period. A generalised regression model was applied to explore the effect of temperature and relative humidity on the change in daily new cases of COVID-19. The regression analysis did not find any significant correlation between temperature, humidity, and change in number of COVID-19 cases. Analysis of the cities with wide-ranging temperature variations showed a negative correlation of COVID-19 transmission (P=0.079) with temperature, but a relatively non-significant correlation with relative humidity (P=0.198). The number of total deaths was also higher in low-temperature countries compared with high-temperature countries. The specific growth rate in COVID-19 cases was decreased by more than 66% after implementation of a lockdown. This growth rate was exponentially decreased over time through the proper implementation of lockdown. Analysis of the real-case scenario and application of predictive models showed that for New York, Lombardy, and Madrid more than 120 days of strict lockdown was required for complete control of the transmission of COVID-19.

Pancreatobiliary Diseases: Evaluation by Transabdominal and Endoscopic Ultrasound.

Pancreaticobiliary diseases are the important causes of morbidity and mortality worldwide. Among the imaging modalities, Transabdominal ultrasound (TUS) is cheap, available, and noninvasive but it has some limitations. Endoscopic ultrasound (EUS) is invasive but it has some diagnostic and therapeutic advantages over TUS. This study was aimed to see the diagnostic yields of EUS and TUS in the pancreatobiliary diseases. This cross sectional study was conducted in Sir Salimullah Medical College Mitford Hospital (SSMC&MH), Dhaka, Bangladesh from March 2017 to February 2019. All (n=222) patients were evaluated clinically and with relevant investigations. TUS and EUS were done in all patients. Endoscopic retrograde cholangiopancreatography (ERCP) was done in 60 patients. Among 222 patients 56.8% were males; mean age was 46±16 years; the main presenting symptoms were abdominal pain and jaundice. In diseases of biliary tree, EUS showed dilated CBD alone or in combination with stone in 50 and 67 cases and TUS showed 37, 63 patients respectively. The difference between the findings of EUS and TUS was statistically significant (p=0.00). In gall bladder, EUS found microlithiasis in 6(2.6%) and sludges in 24(10.8%) cases whereas TUS found microlithiasis in 1(0.5%) and sludges in 17(7.7%) cases respectively (p=0.00). Both EUS and TUS detected cholelithiasis in equal number of patients 46(20.3%). On pancreatic evaluation, EUS and TUS detected pancreatic parenchymal abnormalities in 24(10.8%) and 12(5.5%) patients respectively with significant p value (0.00). In cases of pancreatic and cholangiocarcinoma the difference between the findings of EUS and TUS were statistically significant (p<0.05). EUS detected 7 cases of ampullary/peri-ampullary neoplasms whereas TUS detected only 2 cases. The sensitivity of EUS for detecting CBD dilatation, CBD stones, CBD SOL and pancreatic SOL was 85%, 91%, 93%, and 92% respectively. The sensitivity of TUS for detecting CBD dilatation, CBD stones, CBD SOL and pancreatic SOL was 42%, 52%, 40%, and 37% respectively. EUS is more sensitive than TUS in diagnosing pancreaticobiliary disorders. It is of paramount importance in patients in diagnosing CBD dilatation, choledocholithiasis, biliary microlithiasis and pancreaticobiliary neoplasm. EUS has important role before proceeding to further management by more invasive techniques like ERCP or surgery.

Cytochrome P-450 metabolites mediate norepinephrine-induced mitogenic signaling.

Norepinephrine (NE) stimulates release of arachidonic acid (AA) from tissue lipids in blood vessels, which is metabolized via cyclooxygenase, lipoxygenase (LO), and cytochrome P-450 (CYP-450) pathways to biologically active products. Moreover, NE and AA have been shown to stimulate proliferation of vascular smooth muscle cells (VSMCs) of rat aorta. The purpose of this study was to determine the possible contribution of AA and its metabolites to NE-induced mitogenesis in VSMCs of rat aorta and the underlying mechanism of their actions. NE (0.1 to 10 micromol/L) increased DNA synthesis as measured by [3H]thymidine incorporation in VSMCs, and this effect was attenuated by inhibitors of CYP-450 (17-octadecynoic acid, 5 micromol/L; 12-diabromododec-11-enoic acid, 10 micromol/L; and dibromo-dodecenyl-methylsulfimide, 10 micromol/L) and by the LO inhibitor (baicalein, 20 micromol/L), but not by the cyclooxygenase inhibitor (indomethacin, 5 micromol/L). CYP-450 and LO metabolites of AA, 20-hydroxyeicosatetraenoic acid (HETE) (0.1 to 0.5 micromol/L) and 12(S)-HETE, respectively, increased [3H]thymidine incorporation in VSMCs. Both NE and 20-HETE increased mitogen activated protein (MAP) kinase activity as measured by the in-gel kinase assay. The inhibitor of MAP kinase kinase, PD-98059 (50 micromol/L), attenuated NE as well as 20-HETE induced [3H]thymidine incorporation and MAP kinase activation in VSMCs. These data suggest that products of AA formed via CYP-450, most likely 20-HETE, and via LO mediate NE induced mitogenesis in VSMCs.

Small GTP binding protein Ras contributes to norepinephrine-induced mitogenesis of vascular smooth muscle cells.

Norepinephrine stimulates release of arachidonic acid from tissue lipids. Arachidonic acid metabolites generated through the lipoxygenase and cytochrome P-450 pathways but not cyclooxygenase stimulate mitogen activated protein (MAP) kinase activity and proliferation of vascular smooth muscle cells (VSMC). Moreover, norepinephrine has been shown to activate the Ras/MAP kinase pathway through generation of cytochrome P450 metabolite of arachidonic acid, 20-hydroxyeicosatetraenoic acid (20-HETE). The purpose of this study was to investigate the contribution of Ras in norepinephrine-induced mitogenesis in aortic VSMC. Farnesylation of Ras by farnesyl transferase is required for its full activation. Norepinephrine-induced DNA synthesis, as measured by [3H]-thymidine incorporation, was attenuated by inhibitors of Ras farnesyl transferase FPT III and BMS-191563. These agents also inhibited 20-HETE-stimulated [3H]-thymidine incorporation. In cells transiently transfected with dominant negative Ras (RasN17), norepinephrine, and 20-HETE-induced proliferation of VSMC was attenuated. Both norepinephrine and 20-HETE increased localization of Ras to plasma membrane and MAP kinase activity; FPT III attenuated these effects. These data suggest that VSMC proliferation induced by norepinephrine and 20-HETE is mediated by Ras/MAP kinase pathway.

Calcium/calmodulin-dependent protein kinase IIalpha mediates activation of mitogen-activated protein kinase and cytosolic phospholipase A2 in norepinephrine-induced arachidonic acid release in rabbit aortic smooth muscle cells.

We have investigated the contribution of Ca2+/calmodulin-dependent protein kinase II (CaM kinase II) and mitogen-activated protein kinase (MAP kinase) in norepinephrine (NE)-induced arachidonic acid (AA) release in rabbit aortic vascular smooth muscle cells (VSMC). NE enhanced release of AA via activation of cytosolic phospholipase A2 (cPLA2) but not secretory PLA2 in VSMC prelabeled with [3H]AA. NE (10 microM) enhanced CaM kinase II and MAP kinase activity. In cells transiently transfected with antisense oligonucleotides complementary to the translation initiation sites of CaM kinase II and MAP kinase, NE-induced AA release was inhibited by 100 and 35% respectively. Treatment of cells with PD-098059, a MAP kinase kinase inhibitor, or with MAP kinase antisense oligonucleotide reduced NE-induced activation of MAP kinase and cPLA2. NE-induced MAP kinase and cPLA2 activation was also inhibited in cells treated with a CaM kinase II inhibitor, KN-93, or with CaM kinase II antisense oligonucleotide. On the other hand, inhibition of MAP kinase kinase with PD-098059 or of MAP kinase with antisense oligonucleotides did not alter the NE-induced increase in CaM kinase II activity. Phosphorylation of MAP kinase and CaM kinase II by NE, studied by 32P incorporation and immune complex kinase assays, was inhibited by KN-93. Collectively, these data suggest that CaM kinase II can activate MAP kinase, which in turn activates cPLA2 to release AA for prostacyclin synthesis in the rabbit VSMC. This novel pathway for activation of MAP kinase by CaM kinase II appears to be mediated through stimulation of MAP kinase kinase. Activation of adrenergic receptors with NE in VSMC caused translocation of CaM kinase II, MAP kinase, and cPLA2 to the nuclear envelope only in the presence of extracellular Ca2+. Okadaic acid, which increased phosphorylation and activity, did not translocate these enzymes. Therefore, it appears that in rabbit VSMC, NE, by promoting extracellular Ca2+ influx, increases CaM kinase II activity, leading to activation of MAP kinase and cPLA2 and translocation to the nuclear envelope, resulting in release of AA from the nuclear envelope for prostacyclin synthesis.

Signal transduction mechanisms involved in angiotensin-(1-7)-stimulated arachidonic acid release and prostanoid synthesis in rabbit aortic smooth muscle cells.

This study investigated the signal transduction mechanisms of angiotensin-(1-7) [Ang-(1-7)]- and Ang II-stimulated arachidonic acid (AA) release for prostaglandin (PG) production in rabbit aortic vascular smooth muscle cells. Ang II and Ang-(1-7) enhanced AA release in cells prelabeled with [3H]AA. However, 6-keto-PGF1 alpha synthesis produced by Ang II was much less than that caused by Ang-(1-7). In the presence of the lipoxygenase inhibitor baicalein, Ang II enhanced production of 6-keto-PGF1 alpha to a greater degree than Ang-(1-7). Angiotensin type (AT)1 receptor antagonist DUP-753 inhibited only Ang II-induced [3H]AA release, whereas the AT2 receptor antagonist PD-123319 inhibited both Ang II- and Ang-(1-7)-induced [3H]AA release. Ang-(1-7), receptor antagonist D-Ala7-Ang-(1-7) inhibited the effect of Ang-(1-7), but not of Ang II. In cells transiently transfected with cytosolic phospholipase A2 (cPLA2), mitogen-activated protein (MAP) kinase or Ca(++)-/cal-modulin-dependent protein (CAM) kinase II antisense oligonucleotides, Ang-(1-7)- and Ang II-induced [3H]AA release was attenuated. The CaM kinase II inhibitor KN-93 and the MAP kinase kinase inhibitor PD-98059 attenuated both Ang-(1-7)- and Ang II-induced cPLA2 activity and [3H]AA release. Ang-(1-7) and Ang II also increased CaM kinase II and MAP kinase activities. Although KN-93 attenuated MAP kinase activity, PD-98059 did not affect CaM kinase II activity. Both Ang II and Ang-(1-7) caused translocation of cytosolic PLA2 to the nuclear envelope. These data show that Ang-(1-7) and Ang II stimulate AA release and prostacyclin synthesis via activation of distinct types of AT receptors. Both peptides appear to stimulate CaM kinase II, which in turn, via MAP kinase activation, enhances cPLA2 activity and release of AA for PG synthesis.

Ca2+/calmodulin-dependent protein kinase II and cytosolic phospholipase A2 contribute to mitogenic signaling in myeloblastic leukemia U-937 cells.

The signaling mechanisms downstream of growth factor-stimulated proliferation in myeloid leukemia cells have not yet been fully elucidated. Recent evidence suggests that alternate pathways to the mitogen-activated protein kinase cascade are required. We have previously shown that Ca2+/calmodulin-dependent protein kinase II (CaM kinase II) activates cytosolic phospholipase A2 (cPLA2), which is involved in the proliferation of vascular smooth muscle cells. In the present study, the contribution of this pathway was investigated in the proliferation of U-937 myeloid leukemia cells. In U-937 cells, fetal bovine serum (FBS)-induced proliferation was attenuated by CaM kinase II inhibitor KN-93 but not by its inactive analog KN-92. Inhibitors of cPLA2 (methyl arachidonyl fluorophosphonate and arachidonyl trifluoromethyl ketone) also reduced proliferation of U-937 cells. FBS-induced proliferation was also attenuated by cotransfection with cPLA2 antisense oligonucleotides. These results suggest a role for CaM kinase II and cPLA2 in the proliferation of U-937 cells. FBS stimulated CaM kinase II and cPLA2 activities in a time-dependent manner. Moreover, FBS-stimulated phosphorylation and activation of cPLA2 activation was inhibited by KN-93. FBS-stimulated phosphorylation of CaM kinase II was blocked by KN-93 but not by cPLA2 inhibitors, suggesting that CaM kinase II activates cPLA2. The products of phospholipid hydrolysis produced by cPLA2, lysophosphatidylcholine but not arachidonic acid, increased [3H]thymidine incorporation in U-937 cells. These data suggest that exposure of U-937 cells to FBS promotes phosphorylation and activation of CaM kinase II, leading to stimulation of cPLA2 and generation of lysophosphatidylcholine and resultant proliferation of these cells.

20-Hydroxyeicosatetraenoic acid mediates calcium/calmodulin-dependent protein kinase II-induced mitogen-activated protein kinase activation in vascular smooth muscle cells.

Norepinephrine (NE) and angiotensin II (Ang II), by promoting extracellular Ca2+ influx, increase Ca2+/calmodulin-dependent kinase II (CaMKII) activity, leading to activation of mitogen-activated protein kinase (MAPK) and cytosolic phospholipase A2 (cPLA2), resulting in release of arachidonic acid (AA) for prostacyclin synthesis in rabbit vascular smooth muscle cells. However, the mechanism by which CaMKII activates MAPK is unclear. The present study was conducted to determine the contribution of AA and its metabolites as possible mediators of CaMKII-induced MAPK activation by NE, Ang II, and epidermal growth factor (EGF) in vascular smooth muscle cells. NE-, Ang II-, and EGF-stimulated MAPK and cPLA2 were reduced by inhibitors of cytochrome P450 (CYP450) and lipoxygenase but not by cyclooxygenase. NE-, Ang II-, and EGF-induced increases in Ras activity, measured by its translocation to plasma membrane, were abolished by CYP450, lipoxygenase, and farnesyltransferase inhibitors. An AA metabolite of CYP450, 20-hydroxyeicosatetraenoic acid (20-HETE), increased the activities of MAPK and cPLA2 and caused translocation of Ras. These data suggest that activation of MAPK by NE, Ang II, and EGF is mediated by a signaling mechanism involving 20-HETE, which is generated by stimulation of cPLA2 by CaMKII. Activation of Ras/MAPK by 20-HETE amplifies cPLA2 activity and releases additional AA by a positive feedback mechanism. This mechanism of Ras/MAPK activation by 20-HETE may play a central role in the regulation of other cellular signaling molecules involved in cell proliferation and growth.