Mycobacterium tuberculosis WhiB3 responds to O2 and nitric oxide via its [4Fe-4S] cluster and is essential for nutrient starvation survival

A fundamental challenge in the redox biology of Mycobacterium tuberculosis (Mtb) is to understand the mechanisms involved in sensing redox signals such as oxygen (O2), nitric oxide (NO), and nutrient depletion, which are thought to play a crucial role in persistence. Here we show that Mtb WhiB3 responds to the dormancy signals NO and O2 through its iron-sulfur (Fe-S) cluster. To functionally assemble the WhiB3 Fe-S cluster, we identified and characterized the Mtb cysteine desulfurase (IscS; Rv3025c) and developed a native enzymatic reconstitution system for assembling Fe-S clusters in Mtb. EPR and UV-visible spectroscopy analysis of reduced WhiB3 is consistent with a one-electron reduction of EPR silent [4Fe-4S]2+ to EPR visible [4Fe-4S]+. Atmospheric O2 gradually degrades the WhiB3 [4Fe-4S]2+ cluster to generate a [3Fe-4S]+ intermediate. Furthermore, EPR analysis demonstrates that NO forms a protein-bound dinitrosyl-iron-dithiol complex with the Fe-S cluster, indicating that NO specifically targets the WhiB3 Fe-S cluster. Our data suggest that the mechanism of WhiB3 4Fe-4S cluster degradation is similar to that of fumarate nitrate regulator. Importantly, Mtb DeltawhiB3 shows enhanced growth on acetate medium, but a growth defect on media containing glucose, pyruvate, succinate, or fumarate as the sole carbon source. Our results implicate WhiB3 in metabolic switching and in sensing the physiologically relevant host signaling molecules NO and O2 through its [4Fe-4S] cluster. Taken together, our results suggest that WhiB3 is an intracellular redox sensor that integrates environmental redox signals with core intermediary metabolism.     

Communication skills training for emergency nurses

Objective: To determine the effects of a communication skills training program on emergency nurses and patient satisfaction.Methods: Sixteen emergency nurses attended a 6-week psychoeducation program that was intended to improve their communication skills. The first 3 sessions of the psychoeducation program consisted of theoretical education on empathy and communication. Other sessions covered awareness, active communication, and empathic skills on a cognitive behavioral basis using discussion, role play, and homework within an interactive group. The effects of the program were assessed using a communication skills scale, empathy scale, and patient satisfaction survey and were reflected by the reduction in the number of undesirable events between nurses and patients in the emergency department.Results: The mean communication skill score (177.8±20) increased to 198.8±15 after training (p=0.001). Empathy score also increased from 25.7±7 to 32.6±6 (p=0.001). The patient satisfaction survey of 429 patients demonstrated increased scores on confidence in the nurses (76.4±11.2 to 84.6±8.3; p=0.01); the nurse''s respect, kindness, and thoughtfulness (72.2± 8.1 to 82.1 ± 6,5; p=0.01); individualized attention (71.3± 6.2 to 73.2 ± 9.8; p=0.2); devotion of adequate time to listening (84.6± 9.3 to 89.8 ± 7.6; p=0.03); and counseling and information delivery (71.1± 10.2 to 80.2 ± 9.7; p=0.01). The number of undesirable events and complaints during nurse-patient interactions decreased 66 % from 6 to 2.Conclusion: “Communication Skills Training” can improve emergency nurses'' communication and empathy skills with a corresponding increase in patient satisfaction and reduction of the undesirable events and complaints during nurse-patient interactions.     

Nearly two decades using the check-type to prevent ABO incompatible transfusions: one institution's experience

To detect miscollected (wrong blood in tube [WBIT]) samples, our institution requires a second independently drawn sample (check-type [CT]) on previously untyped, non-group O patients who are likely to require transfusion. During the 17-year period addressed by this report, 94 WBIT errors were detected: 57% by comparison with a historic blood type, 7% by the CT, and 35% by other means. The CT averted 5 potential ABO-incompatible transfusions. Our corrected WBIT error rate is 1 in 3,713 for verified samples tested between 2000 and 2003, the period for which actual number of CTs performed was available. The estimated rate of WBIT for the 17-year period is 1 in 2,262 samples. ABO-incompatible transfusions due to WBIT-type errors are avoided by comparison of current blood type results with a historic type, and the CT is an effective way to create a historic type.     

A variant of ProMACE-CytaBOM chemotherapy for non-Hodgkin's lymphoma with threefold higher drug dose size but identical cumulative dose intensity. A pilot study of the Italian lymphoma study group (GISL)

BACKGROUND AND OBJECTIVE: The positive results of high-dose chemotherapy followed by rescue with bone marrow progenitor cell transplantation are generally ascribed to the high dose size (DS) of the drugs given. However, a concomitant marked increase in dose intensity (DI) is always involved. With the aim of comparing the role of DS and DI in non-Hodgkin's lymphomas, a variant of Fisher's ProMACE-CytaBOM regimen was designed in which the projected cumulative drug DIs remained the same as in the original schedule but the DSs were tripled. DESIGN AND METHODS: Dosages in mg/m(2), route and days of administration were the following: cyclophosphamide 1,950 i.v. on days 1, 64; methotrexate 360 i.v. days 15, 78; vincristine 1.4 iv days 15, 78, 43, 106; etoposide 360 i.v. days 29, 92; epirubicin 120 i.v. days 29, 92; bleomycin 15 i.v. days 43, 106; cytarabine 900 i.v. days 50, 113. Thirty-six outpatients with intermediate- and high-grade non-Hodgkin's lymphomas entered the pilot study; 29 were untreated and 7 had relapse disease. Clinical stage was I in 1 patient, II in 7, III in 5 and IV in 23; 10 had B symptoms; the IPI score was 0-2 in 29 cases and > or =3 in the remaining 7. RESULTS: Of the 29 previously untreated patients, 16 achieved complete remission, 8 partial remission, 4 developed progressive disease and 1 was withdrawn early from the study because of acute viral hepatitis; subsequently 4 relapsed and 3 died (2 of disease progression, 1 of causes unrelated to the disease). In the pre-treated group 3 patients obtained complete remission, 2 partial remission and in 1 patient the disease progressed; 3 of these pre-treated patients died (1 of progressive disease, 1 of a new relapse, 1 of myocardial infarction during therapy). With a 20-month median follow-up, the 30-month overall and relapse-free survival were 0.58 and 0.70, respectively. G-CSF was administered to all but 2 patients, with median delivery throughout the whole regimen of 8, 400 microg per patient. Actual cumulative DI was 0.82+/-0.11. Grade 3-4 hematologic toxicity consisted of anemia in 3 cases, of leukopenia in 8 and of thrombocytopenia in 2; the same grade of non-hematologic toxicity involved the liver in 2 cases, the heart in 1 (the above mentioned death), the digestive mucosa in 2 and the peripheral nerves in 1 patient. INTERPRETATION AND CONCLUSIONS: The iso-DI sequential variant of the ProMACE-CytaBOM regimen can be considered feasibile, relatively non-toxic, and can be given on an out-patient basis. Limited use of G-CSF is required (about 3 vials after each drug administration). Thus, a randomized trial with the original ProMACE-CytaBOM regimen can be designed.     

Molecular determinants of mexiletine structure for potent and use-dependent block of skeletal muscle sodium channels

On the basis of the information about drug receptor on voltage-gated sodium channels, mexiletine (Mex) analogs with substitutions at either the asymmetric carbon atom or the aromatic ring were synthesized as pure enantiomers. The compounds were tested in vitro for their ability to produce voltage- and use-dependent block of sodium currents (I(Na)) of frog muscle fibers by the vaseline-gap voltage-clamp method. In all experimental conditions, the drug potency was highly correlated with the lipophilicity of the group on the asymmetric center, the derivative with a benzyl moiety (Me6) having IC(50) values more than 10 times lower than those of Mex, followed by the phenyl (Me4) and the isopropyl (Me5) derivative. All of the compounds showed a further reduction of IC(50) values at depolarized membrane potentials and at high frequency of stimulation (10 Hz). Mex and Me5, but not Me4, produced a stereoselective tonic block of I(Na), the R-(-) isomers being 2-fold more potent than the S-(+) ones. The removal of both methyl groups from the aromatic ring of Mex (Me3) caused a 7-fold reduction of the potency, whereas similar substitutions on the phenyl derivative Me4 (Me7 and Me8) produced opposite effects. In fact, the IC(50) of R-(-) Me7 for use-dependent block of I(Na) was 30 times lower than that of R-(-) Mex. Me8 and Me7 were stereoselective during both tonic and use-dependent blockade. All of the compounds left-shifted the steady-state inactivation curves in relation to their potency and to the duration of the inactivating prepulse. Finally, the presence of apolar groups on the asymmetric center of mexiletine is pivotal to reinforce hydrophobic interactions with the proposed aromatic residues at the receptor, and lead to potent and therapeutically interesting inactivated channel blockers.