[ETHICAL CHALLENGES IN TREATING CRITICAL CORONAVIRUS PATIENTS: EXPERIENCE FROM THE SHEBA MEDICAL CENTER ON THE FIRST COVID-19 PANDEMIC OUTBREAK]

As the coronavirus pandemic emerged in late 2019, a task force was founded in the Sheba Medical Center and began preparing for the arrival of the pandemic to Israel. Several wards were put in charge of isolated COVID-19 patients. A new intensive care unit was formed for the most critical COVID-19 patients, requiring mechanical ventilation and multi-organ treatment. The Corona ICU began operating in March 2020, with a multi-disciplinary team, gathered from ICU units, an internal medicine ward, an anesthesiology department, social workers and psychologists. Simultaneously, the routine medical center functions in non-corona sections were maintained, as much as possible. The coronavirus pandemic entails challenges of many aspects: an unfamiliar pathogen causing an unknown illness, a necessity for social distancing, ambiguity regarding the risk factors for contamination and illness severity, and medical crews put at risk. Consequently, the pandemic involves ethical, social, economic and moral aspects, affecting the medical crew members and system, the patients and their families, and our society as a whole. In this article we review our joint experience in the Sheba Medical Center Corona ICU, of the medical, ethical and moral dilemmas that emerged from the first COVID-19 wave.

Low-dose alemtuzumab for GvHD prevention followed by prophylactic donor lymphocyte infusions in high-risk leukemia

We analyzed the use of low-dose alemtuzumab in a cohort of 158 consecutive patients who underwent allogeneic PBSC transplantation. Patients with high-risk acute leukemia were prospectively screened for prophylactic donor lymphocyte infusion (pDLI). Lymphocytes were administered repeatedly at low and non-escalating doses (0.5-1 × 10⁶/kg). Low-dose alemtuzumab was effective in prevention of acute GvHD after sibling or well-matched unrelated transplantation, whereas a more intensified approach was needed after mismatched transplantation. The cumulative incidence of chronic moderate/severe chronic-GvHD (cGvHD) was 15.6%. In total, 63 high-risk leukemia patients were eligible for pDLI. Only 1 out of the 39 pDLI recipients relapsed as compared with 7 out of the 24 recipients, who did not receive pDLI due to logistical hurdles. In multivariate analysis, the use of adjuvant lymphocyte therapy was significantly associated with reduced incidence of relapse and improved disease-free survival. In summary, low-dose alemtuzumab confers to a low cGvHD incidence and the administration of pDLIs in this context is very likely to reduce relapse risk in high risk leukemia patients. This is translated in an estimated 5-year probability of GvHD-free and relapse-free survival of 43.3% for the 136 leukemia patients.

Lactic Acidosis as Presenting Symptom of Thiamine Deficiency in Children with Hematologic Malignancy

Thiamine is an essential component of cellular metabolism and its deficiency results in potentially life-threatening events and profound lactic acidosis through anaerobic metabolism. Acute decompensation in thiamine-deficient patients may manifest as neurologic or cardiovascular changes, with severe lactic acidosis as the presenting symptom. We describe two hematological pediatric patients with thiamine deficiency and hemodynamic instability who improved following thiamine supplements. Thiamine levels were inversely proportional to lactic acidosis; specifically, lower thiamine levels were related to higher lactate levels. We recommend that children with hematological malignancies admitted to a pediatric intensive care unit with low blood pressure and lactic acidosis should be considered for thiamine-level screening and receive supplementation accordingly.

Cytosolic phospholipase A2 is responsible for prostaglandin E2 and leukotriene B4 formation in phagocyte-like PLB-985 cells: studies of differentiated cPLA2-deficient PLB-985 cells

Our previously established model of cytosolic phospholipase A(2) (cPLA(2))-deficient, differentiated PLB-985 cells (PLB-D cells) was used to determine the physiological role of cPLA(2) in eicosanoid production. Parent PLB-985 (PLB) cells and PLB-D cells were differentiated toward the monocyte or granulocyte lineages using 5 x 10(-)(8) M 1,25 dihydroxyvitamin D(3) or 1.25% dimethyl sulfoxide, respectively. Parent monocyte- or granulocyte-like PLB cells released prostaglandin E(2) (PGE(2)) when stimulated by ionomycin, A23187, opsonized zymosan, phorbol 12-myristate 13-acetate, or formyl-Met-Leu-Phe (fMLP), and monocyte- or granulocyte-like PLB-D cells did not release PGE(2) with any of the agonists. The kinetics of cPLA(2) translocation to nuclear fractions in monocyte-like PLB cells stimulated with fMLP or ionomycin was in correlation with the kinetics of PGE(2) production. Granulocyte-like PLB cells, but not granulocyte-like PLB-D cells, secreted leukotriene B(4) (LTB(4)) after stimulation with ionomycin or A23187. Preincubation of monocyte-like parent PLB cells with 100 ng/ml lipopolysaccharide (LPS) for 16 h enhanced stimulated PGE(2) production, which is in correlation with the increased levels of cPLA(2) detected in these cells. LPS preincubation was less potent in increasing PGE(2) and LTB(4) secretion and did not affect cPLA(2) expression in granulocyte-like PLB cells, which may be a result of their lower levels of surface LPS receptor expression. LPS had no effect on monocyte- or granulocyte-like PLB-D cells. The lack of eicosanoid formation in stimulated, differentiated cPLA(2)-deficient PLB cells indicates that cPLA(2) contributes to stimulated eicosanoid formation in monocyte- and granulocyte-like PLB cells.

Essential requirement of cytosolic phospholipase A(2) for stimulation of NADPH oxidase-associated diaphorase activity in granulocyte-like cells

We have previously established a model of cytosolic phospholipase A(2) (cPLA(2))-deficient differentiated PLB-985 cells (PLB-D cells) and demonstrated that cPLA(2)-generated arachidonic acid (AA) is essential for NADPH oxidase activation. In this study we used this model to investigate the physiological role of cPLA(2) in regulation of NADPH oxidase-associated diaphorase activity. A novel diaphorase activity assay, using 4-iodonitrotetrazolium violet as an electron acceptor, was used in permeabilized neutrophils and PLB-985 cells differentiated toward the granulocytic or monocytic phenotypes. Phorbol 12-myristate 13-acetate, guanosine 5'-3-O- (thio)triphosphate (GTP gamma S), or FMLP stimulated a similar diphenylene iodonium-sensitive diaphorase activity pattern in neutrophils and in differentiated parent PLB-985 cells. This diaphorase activity was not detected in undifferentiated cells, but developed during differentiation. Furthermore, diaphorase activity could not be stimulated in permeabilized neutrophils from X-linked CGD patients and in differentiated gp91(phox)-targeted PLB-985 cells that lacked normal expression of gp91(phox), but was restored to these cells following transduction with retrovirus encoding gp91(phox). The differentiated PLB-D cells showed no diaphorase activity when stimulated by either GTP gamma S or FMLP, and only partial activation when stimulated with phorbol 12-myristate 13-acetate. Diaphorase activity in response to either agonists was fully restored by the addition of 10 microm free AA. The permeabilized cell 4-iodonitrotetrazolium violet reduction assay offers a unique tool for the evaluation of NADPH oxidase-associated diaphorase activity in stimulated whole cells. These results establish an essential and specific physiological requirement of cPLA(2)-generated AA in activation of electron transfer through the FAD reduction center of NADPH oxidase.

The NADPH oxidase diaphorase activity in permeabilized human neutrophils and granulocytic like PLB-985 cells

The phagocyte NADPH oxidase is a multicomponent transport chain that generates superoxide, a precursor of microbicidal oxidants, important for host defense. This transport chain is contained mainly in the large membrane subunit of the oxidase (gp91phox), and transfers electrons from cytosolic NADPH, through FAD binding and heme centers, to molecular oxygen (Babior, 1999; Fujii and Kakinuma, 1991; Rotrosen et al., 1992; Segal and Abo, 1993). Cross et al. have recently described a novel NADPH oxidase diaphorase activity present in the membrane fraction of activated neutrophils, using a cell free model (Cross et al., 1994). This diaphorase activity is measured by the artificial electron acceptor 4-iodonitrotetrazolium violet (INT) and is attributed to the reduction of the flavin center of the flavocytochrome (Cross et al., 1994; Li and Guillory, 1997). In the present study we establish a system for detecting diaphorase activity in intact cells. Neutrophils and PLB-985 cells, that were differentiated using 1.25% dimethyl sulfoxide (DMSO) to granulocyte phenotype, were permeabilized by electroporation, and diaphorase activity was determined using INT. Neutrophils and differentiated PLB-985 cells stimulated by PMA or GTP gamma S showed a diaphorase activity that was not present in unstimulated differentiated cells. The diaphorase activity could not be detected in undifferentiated cells and was developed during differentiation. The pattern of diaphorase activity in stimulated parent differentiated PLB cells was similar to that observed in stimulated human neutrophils. The permeabilized-INT cell system offers a unique tool for the evaluation of NADPH oxidase diaphorase activity, in whole cells.