Teacher profiles in higher education: the move to online education during the COVID-19 crisis.

During the COVID-19 pandemic, teachers were forced to move their teaching completely online. While some seized the opportunity to learn and innovate, others experienced difficulties. This study provides insights into the differences between university teachers during the COVID-19 crisis. A survey among university teachers (N = 283) was conducted to investigate their attitudes towards online teaching, beliefs about students' learning, level of stress experienced, self-efficacy and beliefs about their own professional development. Employing a hierarchical cluster analysis, four distinct teacher profiles were found. Profile 1 was critical but eager; Profile 2 was positive but stressed; Profile 3 was critical and reluctant; Profile 4 was optimistic and easy-going. The profiles differed significantly in their use and perception of support. We suggest that teacher education research should carefully consider sampling procedures or take a person-centred research approach and that universities should develop targeted forms of teacher communication, support and policy.

Phospholipase A2 (PLA2) activity in bovine pulmonary artery endothelial cells.

We have investigated the role of recombinant human interleukin-1 beta (rIL-1 beta) and recombinant human tumor necrosis factor alpha (rTNF-alpha) on PLA2 activity, protein synthesis and eicosanoid production in bovine pulmonary artery endothelial cells. Cellular PLA2 activity increased 4-fold and production of PGE2 increased 3-fold at 1-2 hrs in the presence of 10 units/ml rIL-1 beta. PLA2 activity increased 3-fold at 30 min and PGE2 production increased 2-fold with 5 x 10(-9) M rTNF-alpha. The data show that endothelial cells respond more rapidly to rIL-1 beta (2-6 hr) and rTNF-alpha (30 min) than do chondrocytes and synovial cells (6-16 hrs), suggesting endothelial cells may play a primary role in initiating the inflammatory response.

Characterization of extracellular phospholipase A2 (PLA2) activity in fluid and peritoneal cells from casein-treated rats.

Extracellular phospholipase A2 activity (PLA2) found in the fluid and cells of the peritoneal cavity of rats injected with casein is described. PLA2 activities from both the fluid and cells require Ca2+ and have pH optima of 7. Acid-extraction increased PLA2 activity in the polymorphonuclear leukocyte (PMN) homogenates 20-fold but not the PLA2 activity in the extracellular fluid. Acid extraction also increased the sensitivity of the PLA2 activities to standard inhibitors. Since the PLA2 activities described in this model have characteristics similar to other inflammatory PLA2s, including human synovial fluid PLA2, casein stimulation should prove useful for testing potential inhibitors.

Kinetics of phospholipase A2, arachidonic acid, and eicosanoid appearance in mouse zymosan peritonitis.

Intraperitoneal injection of zymosan into mice induces a peritonitis characterized by cellular influx, plasma leakage and the appearance of arachidonic acid (AA) metabolites. We report that zymosan injection also stimulates the accumulation of AA, docosahexaenoic acid, linoleic acid, and phospholipase A2 (PLA2) activity. The amount of the unsaturated fatty acids (UnFA) varies both with the zymosan dose and time. Significantly increased levels of UnFA were first detected 15 min after zymosan injection. Maximal levels of the UnFA were reached 1 to 2 h post zymosan injection (AA: 725 +/- 29 ng/mouse, docosahexaenoic acid: 296 +/- 23 ng/mouse, linoleic acid: 4489 +/- 179 ng/mouse) and declined to saline control levels by 8 h. PLA2 activity was significantly increased 5 to 15 min after zymosan injection. Maximal levels of PLA2 activity occurred 15 to 30 min after zymosan injection (31.8 +/- 9.1 nmol phospholipid/mg protein/h) and then decreased by 30% through 24 h. Neither the appearance of UnFA nor PLA2 activity correlated with cellular influx, but both were coincident with plasma exudation at 5 to 15 min after zymosan. However, maximal exudation occurred 1 to 2 h post zymosan injection similar to that seen with the UnFA but not PLA2. These latter results suggest that a significant portion of the UnFA found in the peritoneal cavity of zymosan-injected mice originates from the plasma. PLA2 activity at the early time points (5 to 15 min) may also contribute to the levels of UnFA via hydrolysis of tissue and/or cellular phospholipids.

Extracellular phospholipase A2 activity in two in vivo models of inflammation.

Two "in vivo" models of inflammation have been used to investigate the role of phospholipases A2 (PLA2) in inflammation. These models are casein-induced peritonitis in the rat and zymosan-induced peritonitis in the mouse. The extracellular PLA2 activities from peritoneal lavage fluid in these two models are similar: they are calcium dependent and have broad neutral pH optima. However, the relationship between extracellular PLA2 activity and cell influx in these models are not identical. In zymosan peritonitis, PLA2 activity preceded peak cell influx, reaching a maximum within 15 min after zymosan injection, while cell influx peaked by 8 hr. In casein-induced peritonitis, the PLA2 activity peaked at 24 hr, while cell influx continued through 48 hr. The origins of the PLA2 activities in both models remain unclear; one potential source is the plasma. Understanding the role of extracellular PLA2 activity in "in vivo" models, and investigating specific inhibitors in these models may aid in our understanding of the role of extracellular PLA2 in diseases such as rheumatoid arthritis, endotoxin shock and pancreatitis.

Effects of recombinant interleukin-1 beta on phospholipase A2 activity, phospholipase A2 mRNA levels, and eicosanoid formation in rabbit chondrocytes.

We have investigated the effects of recombinant interleukin-1 beta (rIL-1 beta) on phospholipase A2 activity (PLA2), PLA2 messenger RNA levels, and eicosanoid production in rabbit chondrocytes. Phospholipase A2 activity increased 5 fold with exposure to 1.6 x 10(-11) M rIL-1 beta for 20 hours. An mRNA specific for an extracellular PLA2 was detected by RNA blot hybridization after treatment of the cells with rIL-1 beta. Hydroxylated derivatives of arachidonic acid, including prostaglandins, leukotriene B4, 5-hydroxyeicosa 6E, 8Z, 11Z, 14Z-tetraenoic acid, 12-hydroxyeicosa 5Z, 8Z, 10E, 14Z-tetraenoic acid and 15-hydroxyeicosa 5Z, 8Z, 11Z, 13E-tetraenoic acid increased in cells after rIL-1 beta treatment.

Pretreatment with EDU decreases rat lung cellular responses to ozone.

The phenylurea compound EDU (N-[2-(2-oxo-1-imidazolindinyl)ethyl]-N'-phenylurea) has been shown to protect plants from the damaging effects of ozone exposure. Models of rat lung injury, based on acute exposure to 2 ppm ozone for 3 hr and on exposure to 0.85 ppm ozone for 2 days, were used to determine whether EDU pretreatment of rats protected lungs from oxidant injury. Rats were pretreated with 100 mg/kg body wt EDU by ip administration for 2 days prior to and on the days of ozone exposure. No adverse toxicological effects of EDU pretreatment were observed. Lung superoxide dismutase (SOD) and catalase (CAT) activities were significantly enhanced from 636 to 882 U/lung and from 599 to 856 U/lung, respectively. One day following acute exposure (2 ppm for 3 hr), an ozone-induced increase of polymorphonuclear leukocytes (PMNs) from 0.01 to 1.18 million cells/lung was decreased to 0.68 million by EDU pretreatment. No alteration occurred in the degree of lung permeability indicated by increased lavage fluid albumin. EDU pretreatment also significantly decreased ozone-induced increases in PMN recovery after 2 days exposure to 0.85 ppm ozone from 5.54 to 2.12 million cells/lung. However, in this second case, EDU pretreatment reduced the observed ozone damage, indicated by a decrease in lavage fluid albumin and by a decrease in the macrophage and lymphocyte infiltration associated with this length of ozone exposure. The observation that EDU-treated cultured pulmonary arterial endothelial cells increased SOD and CAT activities identified a potential lung site of EDU interaction. These data demonstrated that although EDU pretreatment appears not to prevent initial ozone damage, it does reduce the infiltration of PMNs and might therefore prevent amplification of the injury associated with this cell type.

Phospholipase A2 (PLA2) activity in rabbit chondrocytes.

The effects of recombinant interleukin-1 beta (rIL-1 beta), recombinant tumor necrosis factor (rTNF alpha) and two growth factors, basic fibroblast growth factor (bFGF) and epidermal growth factor (EGF) on PLA2 activity and prostaglandin E2 (PGE2) release were investigated using rabbit chondrocytes. Cellular PLA2 activity increased 2-10 x above controls in the presence of 8 x 10(-12) M (5 U) rIL-1 beta or 5 x 10(-9) M rTNF alpha after 20 hr incubation. PLA2 activity remained constant with 1-50 ng/ml of either growth factor. PGE2 release significantly increased (p less than 0.05) when the chondrocytes were incubated with rIL-1 beta, bFGF and EGF alone, but not with rTNF alpha above. These data suggest PLA2 activity and PGE2 release are not coordinately regulated in rabbit chondrocytes.

Phospholipase A2 (PLA2) activity in undifferentiated U937 cells.

PLA2 activity has been described in U937 cells. The present study characterized PLA2 activity in these undifferentiated cells. Cells were grown in suspension culture, harvested by centrifugation, and washed and homogenized in a neutral buffer containing standard proteinase inhibitors. A low speed supernatant was fractionated either by acid extraction or by sucrose density gradient centrifugation. PLA2 activity was measured using either L-alpha-1-palmitoyl-2-arachidonoyl[1-14C]-phosphatidylcholine or heat-inactivated [3H]oleic acid-labeled E. coli as substrates. Substrate-specific PLA2 activity was found in the acid-extracted and in the 25% sucrose fractions. Standard inhibitors were investigated with these PLA2 activities. Our results suggest undifferentiated U937 cells contain three distinct PLA2 activities. This is the first indication that more than one PLA2 activity is present in undifferentiated U937 cells.

Extracellular phospholipase A2 activity in cell free peritoneal lavage fluid from mice with zymosan peritonitis.

The kinetics and appearance of extracellular phospholipase A2 (PLA2) activity and its relationship to the appearance of arachidonic acid (AA) metabolites in the peritoneal cavity of mice injected with zymosan is described. AA metabolites levels including leukotriene C4 (LTC4) were maximum 15-30 min after zymosan. Peak PLA2 activity was also found 15-30 min after zymosan and was significantly increased above levels found in saline control exudates (3.83 +/- 0.89 and 0.35 +/- 0.11, respectively, p less than or equal to 0.05). Results show that an extracellular PLA2 is present in zymosan peritonitis.

Induction of antioxidant enzyme activities by a phenylurea derivative, EDU.

Oxygen free radicals have the potential to mediate cell injury. Defenses against such radicals include the antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-PX). The purposes of this study were (1) to develop an in vitro model using human cells in which to investigate a potential pharmacologic agent as an inducer of these antioxidant enzymes; (2) to investigate the phenylurea derivative N-[2-(2-oxo-1-imidazolindinyl)ethyl]-N-phenylurea (EDU) in this model with paraquat (PQ) serving as the positive control; and (3) to determine if induction of the antioxidant enzymes by EDU occurs in vivo. Human gingival fibroblasts (Gin-1) were used as the target cell in vitro; PQ and EDU, an inducer of SOD and CAT activities in plants, were evaluated as antioxidant enzyme inducers. Total SOD activity in Gin-1 cells increased 2-fold (p less than 0.05) in the presence of 1.0 mM PQ for 18-48 hr compared with untreated controls. Gin-1 cells incubated with 0.25-2.0 mM PQ for 24 hr had significantly increased total SOD (1.5 to 2.0-fold; p less than 0.05). CAT activity increased with 1.0 and 2.0 mM PQ (p less than 0.05). In the presence of PQ, GSH-PX activity decreased (p less than 0.05) in a concentration-dependent manner, indicating inactivation of this enzyme. No toxicity, indicated by lactate dehydrogenase released into the incubation medium, was noted at PQ concentrations below 5.0 mM. In the presence of 0.125-2.0 mM EDU, total SOD activity in Gin-1 cells significantly increased (1.5 to 2.0-fold; p less than 0.05). CAT activity significantly increased in a dose-dependent manner (p less than 0.05), while GSH-PX activity remained constant following exposure to 0.125-2.0 mM EDU. Intraperitoneal administration of EDU to rats twice a day for 2 days at 100 mg/kg induced SOD activity in heart, liver, and lung compared to controls (p less than 0.05). CAT activity increased in the liver 56% and in the lung 36% (p less than 0.05). GSH-PX activity remained constant. Our findings indicate that Gin-1 cells are a useful model in which to study inducers of antioxidant enzymes in vitro and that the phenylurea compound EDU induces SOD and CAT activities both in vitro and in vivo.

Biochemical and pharmacologic characterization of a phosphatidylinositol-specific phospholipase C in rat neutrophils.

The phosphatidylinositol (PI)-specific phospholipase C (PLC) activity contained in sonicates of casein-elicited (4-6 hr) rat neutrophils has been identified and characterized. With phosphatidylinositol (PI) as the substrate, PLC activity is found both in the supernate and pellet of a 100,000g spin of the neutrophil sonicate. Further fractionation of the crude sonicate by centrifugation on discontinuous sucrose gradients indicates that the PLC activity is predominantly cytosolic with lesser amounts of activity found in the plasma membrane and granule enriched fractions. Hydrolysis of PI by the sonicate PLC is linear for 15-20 min at 37 degrees C and also with respect to the amount of sonicate protein added. The enzyme shows selectivity for PI with little, if any, hydrolytic activity towards other phospholipids such as phosphatidylethanolamine (PE), phosphatidylserine (PS), or phosphatidylcholine (PC). The PLC activity has a pH optimum of 5.5-6.0, is enhanced 1.5-3-fold by the addition of deoxycholate, and is Ca++ dependent. Kinetic analysis of the PLC hydrolysis of PI yields an apparent Km of 240 +/- 85 microM and a Vmax of 34.3 +/- 17.0 nmol/min/mg protein (n = 3). Similarly, when phosphatidylinositol 4,5 bisphosphate (PIP2) is used as substrate, an apparent Km of 109 +/- 66 microM and a Vmax of 14.3 +/- 10.4 nmol/min/mg (n = 3) protein is obtained. These data suggest that PIP2 may be a slightly better substrate for the PMN PLC relative to PI. Finally, a variety of drugs previously reported to inhibit platelet PLC activity in vitro were tested for their ability to inhibit rat PMN PLC. Of the compounds tested, none were potent (i.e., IC50 values less than or equal to 100 microM) inhibitors of the PMN PLC.

Maturation of embryonic chick liver delta-aminolevulinate synthase: precursor pools and regulation by intra-cellularly produced heme.

1. Immunoblot analyses were carried out to determine the relative distributions of delta-aminolevulinate synthase (ALA synthase) in mitochondrial and cytosol fractions prepared from embryos at different times after injections with allylisopropylacetamide (AIA). 2. The results indicated that the molecular mass of mature ALA synthase (Mr 65,000) increased with time in mitochondria. 3. At no time was the precursor form (Mr 75,000) of the enzyme detected either in mitochondria or in the cytosol. 4. In primary cultures of hepatocytes, where the increased production of ALA synthase had been induced with AIA, addition of delta-aminolevulinic acid (ALA) and Fe2(SO4)3 into the culture medium completely blocked the processing of the precursor form of the enzyme. 5. On the other hand, the addition of ALA together with deferoxamine mesylate into the medium had no detectable effect on the maturation of ALA synthase in the hepatocytes. 6. The results indicated: first, that upon induction of porphyria the pools of pre-ALA synthase in liver are relatively low in chick embryos when compared with those in other organisms; and second, that increased heme production by the hepatocytes caused the inhibition of processing of the precursor form of ALA synthase.

Acute lung inflammation in rats induced by phorbol myristate acetate (PMA).

Intratracheal administration of PMA produces acute lung injury in part due to the generation of O2-derived free radicals. This study evaluated the role of the antioxidant enzyme superoxide dismutase (SOD) in PMA-induced lung injury in the rat. PMA was instilled into rats intratracheally (20-60 micrograms/kg), and the lungs were lavaged 4 hr later. Total number of cells recovered from lavage after PMA treatment was not different from the total number recovered from controls; lavagable PMNs increased in a dose-dependent manner. Albumin in lavage fluid (an index of lung vascular permeability) was significantly increased at 60 micrograms/kg PMA. SOD (10,000 U) + PMA (60 micrograms/kg) reduced the albumin level but significantly increased both total number of cells and number of PMNs recovered from lavage fluid. To investigate the possibility that SOD decreases the ability of PMNs to adhere, PMN aggregation was measured in vitro. The results indicated that 10,000 U SOD can inhibit PMA-induced aggregation by 50%. In contrast, aggregation to other stimuli (e.g., fMet-Leu-Phe, A23187) was unaffected by SOD. We conclude SOD prevents PMA-induced lung permeability and diminishes PMN adherence.

Biogenesis of embryonic chick liver delta-aminolevulinate synthase: regulation of the level of mRNA by hemin.

The effects of hemin on the concentration of the mRNA for delta-aminolevulinate synthase (ALA synthase) and on the association of the messenger with polysomes were investigated in primary cultures of embryonic chick hepatocytes incubated with allylisopropylacetamide (AIA). A synthetic 24-mer DNA complementary to ALA synthase mRNA was used to determine by solution hybridization the effects of AIA and of AIA plus hemin on the ALA synthase-specific RNA sequences in the cells. The results indicated that ALA synthase mRNA concentrations increased significantly in hepatocytes incubated for 5 h with AIA (0.075 mg/ml), and that hemin in the medium (2 or 10 microM) blocked the increase in the messenger. When delta-aminolevulinic acid (ALA) and FeCl3 were added into the culture medium (1 mM and 5 microM, respectively), the increase in ALA synthase mRNA brought on by AIA was also inhibited. Neither ALA nor FeCl3, when individually added to the cultures, was as effective as the combination of the two. The results with ALA + FeCl3 suggested that stimulation of intracellular production of heme was also effective in blocking the increase in ALA synthase mRNA caused by AIA. Finally, the distributions of ALA synthase mRNA were compared in polysomes isolated from hepatocytes which had been incubated with AIA for 5 h in the presence and absence of 10 microM hemin in the medium. Although a drop was detected in the concentration of ALA synthase mRNA in polysomes from hepatocytes incubated with hemin for 30 min, the decrease was explained by the effect of hemin on the mRNA concentration in the cells.

Biogenesis of mitochondrial proteins. Regulation of production of delta-aminolaevulinate synthase by haemin in embryonic-chick liver.

The effect of haemin on the biogenesis of delta-aminolaevulinate synthase (ALA synthase) was investigated in primary cultures of embryonic-chick liver. The activity of the enzyme and the amount of the enzyme detected by 'immune-blotting' were determined in hepatocytes incubated with the porphyrogenic agent allylisopropylacetamide. The results of these studies indicated that the loss in ALA synthase activity in cells incubated in the presence of haemin (10 microM) was roughly proportional to a loss in the immune-reactive mass of the enzyme. Haemin was as effective as cycloheximide in causing depletion of ALA synthase in hepatocytes. We had previously established that haemin blocked the maturation of the precursor of ALA synthase [Ades (1983) Biochem. Biophys. Res. Commun. 110, 42-47]. From results reported in the present paper on analyses of immune-precipitated ALA synthase after pulse-labelling with [35S]methionine in the presence and in the absence of haemin, we determined that the inhibition of processing of pre-ALA synthase in cells by haemin was concentration-dependent. A concentration of 2 microM in the culture medium blocked the processing of pre-ALA synthase by 50% in hepatocytes. We also determined that, after inhibition of its maturation by haemin, pre-ALA synthase turned-over with a half-time of 30 min; on the other hand, mature ALA synthase turned-over with a half-time of 120 min.

Instructions, feedback, and reinforcement in reducing activity levels in the classroom.

The biomotometer, an electronic device which simultaneously measures motor activity and provides auditory feedback, was used in combination with material reinforcers in an experiment to reduce children's activity level in a classroom setting. Subjects were nine boys and two girls, aged 9--13, from a day hospital program for emotionally disturbed children. After five baseline trials, each child had five contingent reinforcement trials in which he/she received feedback "beeps" from the biomotometer and was given toy or candy rewards after each trial in which activity fell at least 20% below mean baseline level. Then five noncontingent reinforcement trials were run in which children received rewards for wearing the apparatus without the feedback attachment. Results indicated that the intervention "package," including instructions, feedback, and contingent reinforcement, was successful in all five trials for 8 of 11 children. Activity levels increased during the final noncontingent phase.

Activity level: a comparison between actometer scores and observer ratings.

Activity level of 13 boys (aged 9-13) from a day hospital program was measured using actometers in classroom, gym, woodshop, and group therapy settings. Ratings of Ss' activity were obtained from mothers using the Werry scale, and from six clinical staff familiar with the Ss using the Davids scale. It was predicted that activity ratings would have situationally specific relationships with actometer-measured activity level according to the rater's opportunities for observation. Comparisons between measures indicated that all clinical staff ratings correlated significantly with actometer activity in the classroom (r = .49 to r = .73), while mothers' ratings correlated significantly with actometer activity in gym (r = .67), and woodshop (r = .77), and with overall activity (r = .65), a combined measure derived from actometer scores in the four conditions tested. Five of six clinical staff raters showed significant interrater reliability (r = .58 to r = .83). Results are discussed in terms of their implications for solution of current problems in assessment of activity level and hyperactivity.

Modification of activity level through biofeedback and operant conditioning.

The biomotometer, an electronic device that simultaneously measures activity and provides auditory feedback to the subject, was used in combination with material reinforcers in two experiments attempting to modify activity level in children. In the first study the activity level of an 11-year-old highly active boy was decreased below mean baseline during conditioning in a classroom setting. His level of activity returned to baseline when feedback was withdrawn. In the second study, activity level of a 10-year-old hypoactive boy was increased over mean baseline level during conditioning in a free-play setting, and returned to slightly below baseline during five extinction trials. Results of these studies indicate that the biomotometer is a useful instrument for modification of activity level.