Pulmonary infiltrates in neutropenic patients with acute leukemia during chemotherapy: outcome and prognostic factors

STUDY OBJECTIVE: To determine predictors of mortality from pulmonary infiltrates in neutropenic patients with acute leukemia during chemotherapy, and the significance of those factors related to the underlying malignancy and its therapy as well as of those related to the severity of the illness associated with pulmonary infiltrates. DESIGN: A historical cohort study. SETTING: A university teaching hospital and tertiary referral center. PATIENTS AND METHODS: Overall, 53 patients with neutropenia during chemotherapy and with first episodes of pulmonary infiltrates during a 4-year period were studied. Prognostic analysis included 38 variables. Multivariate analyses were performed by logistic regression. RESULTS: The survival rate from pneumonia was 57% (30/53). The following eight parameters were significantly associated with death in univariate analysis: comorbidity present; development of "late" pulmonary infiltrates (> or = 14 days after hospital admission); heart rate > or = 100 beats/min; a ratio heart rate/systolic blood pressure (HR/SBP) > or = 1.2; urea nitrogen > 7 mmol/L; radiographic score > or = 3; neutropenia < 1.0x10(9)/L at the treatment end point; and failed complete remission. In a multivariate model including only parameters available at diagnosis of pulmonary infiltrates, the presence of a ratio HR/SBP > or = 1.2 and of a radiographic score > or = 3 remained independently associated with death. In a second model also including the evolutionary parameter neutropenia < or = 1.0x10(9)/L at the treatment end point, both parameters remained significant together with neutropenia <1.0x 10(9)/L at the treatment end point. The presence of a ratio HR/SBP > or = 1.2 was a strong marker of early death. CONCLUSION: Both therapy- and malignancy-associated neutropenia as well as the severity of illness associated with pulmonary infiltrates are independent prognostic factors. Patients with a ratio HR/SBP > or = 1.2 at diagnosis of pulmonary infiltrates suffer from potentially reversible acute illness, are at risk for early death and, therefore, may be appropriate candidates for treatment in an ICU.     

The artificial heart and neuromonitoring? Technical and clinical aspects

There is a steady progress in the development of artificial heart and circulatory assist devices. There is also no doubt that further advances in energy systems, materials, and electronics will provide for smaller and more reliable electrically driven blood pumps, but the present engineering design appears to be adequate to provide devices satisfactory for initial clinical use. Due to problems in the availability of suitable donor hearts, the concept of replacing the natural heart with an artificial heart as a "bridge to transplantation" has gained attention in recent years. The present paper shows technical and clinical aspects of multivariable electrophysiologic neuromonitoring in a patient with an artificial heart assist device in the intensive care unit. The data (EEG, 40 Hz brain oscillations, brainstem auditory- and somatosensory evoked potentials) are discussed with respect to the influence of the artificial heart on their quality and reliability. Reasons for artifacts and problems of interpretation are shown.     

Sequence-based differentiation of strains in the Mycobacterium avium complex

The complete 16S-23S rDNA internal transcribed spacer (ITS) was sequenced in 35 reference strains of the Mycobacterium avium complex. Twelve distinct ITS sequences were obtained, each of which defined a "sequevar"; a sequevar consists of the strain or strains which have a particular sequence. ITS sequences were identified which corresponded to M. avium (16 strains, four ITS sequevars) and Mycobacterium intracellulare (12 strains, one ITS sequevars). The other seven M. avium complex strains had ITS sequences which varied greatly from those of M. avium and M. intracellulare and from each other. The 16S-23S rDNA ITS was much more variable than 16S rDNA, which is widely used for genus and species identification. Phylogenetic trees based on the ITS were compatible with those based on 16S rDNA but were more detailed and had longer branches. The results of ITS sequencing were consistent with the results of hybridization with M. avium and M. intracellulare probes (Gen-Probe) for 30 of 31 strains tested. Serologic testing correlated poorly with ITS sequencing. Strains with the same sequence were different serovars, and those of the same serovar had different sequences. Sequencing of the 16S-23S rDNA ITS should be useful for species and strain differentiation for a wide variety of bacteria and should be applicable to studies of epidemiology, diagnosis, virulence, and taxonomy.     

Grafting of enzymes on collagen films using Woodward''s reagent "K" and a water-soluble carbodiimide derivative

Two new methods of activation were developed to graft enzymes on collegen films. They involved chemical modifications of surface groups of collagen either by Woodward's reagent "K" or by EDC, a water-soluble derivative of carbodiimide. EDC was a better coupling agent and a detailed study was conducted with this agent. It could be used either in a global method of activation and coupling, or in a two-step procedure of activation of collagen, followed by spontaneous coupling of enzyme. All enzymes tested were successfully bound: malate dehydrogenase, lactate dehydrogenase, aspartate aminotransferase, urease, creatine kinase, hexokinase. The influence on the yield of grafted enzyme, of pretreatment of films, time and temperature of EDC activation, concentration of EDC and enzyme, protecting agents was studied. Stability of enzyme activity on storage was greatly increased after grafting. A co-grafted dual system creatine kinase/heoxkinase, was achieved which exhibited a good efficiency. A striking renaturing process at 0-4degreesC after thermal denaturation, was observed with hexokinase.     

Brushless DC motor drives supplied by PV power system based on Z-source inverter and FL-IC MPPT controller

This paper discusses operation performance of a water pumping system consist of a brushless dc (BLDC) motor coupled a centrifugal pump and accompanying a Z-source inverter (ZSI) fed by a photovoltaic (PV) array, to be improved. Despite conventional double-stage power converters, this paper proposes utilizing a single-stage ZSI to extract the maximum power of the PV array and supply the BLDC motor simultaneously. Utilizing the ZSI provides some inherent advantages such as high efficiency and low cost, which is very promising for PV systems due to its novel voltage buck/boost capability. In addition, in order to precisely perform the maximum power point tracking (MPPT) of the PV array the fuzzy logic-incremental conductance (FL-IC) MPPT scheme is proposed. The proposed FL-IC MPPT scheme provides enough modification to the conventional IC method to enjoy an appropriate variable step size MPPT control signal for the ZSI. Moreover, direct torque control (DTC) is found more effective in comparison with hysteresis current control with current shaping to drive the BLDC motor, because it benefits from faster torque response, reduced torque ripple, less sensitivity to parameters variations, and simple implementation. In the mean time, due to the frequently variations of the PV power generation; delivered mechanical power to the centrifugal pump is variable. Thus, the BLDC motor should be driven with variable reference speed. In order to improve the speed transient response of the BLDC motor and enhance the energy saving aspect of the system, it should enjoy a high quality dynamic response characteristic. Therefore, to realize these purposes, particle swarm optimization (PSO) has been proposed to regulate the proportional-integral-derivative (PID) parameters of the BLDC motor speed controller. The system configuration, operation principle and control methods are presented in detail. Finally, the proposed system was simulated in different operation conditions of the PV array by computer simulations and the effectiveness of the proposed control strategies has been validated by comparative studies and simulation results.     

Three-dimensional structure of lipoamide dehydrogenase from Pseudomonas fluorescens at 2.8 A resolution. Analysis of redox and thermostability properties

The structure of Pseudomonas fluorescens lipoamide dehydrogenase, a dimeric flavoenzyme with a molecular mass of 106,000 daltons, was solved by the molecular replacement method and refined to an R-factor of 19.4% at 2.8 A resolution. The root-mean-square difference from ideal values for bonds and angles is 0.019 A and 3.8 degrees, respectively. The structure is closely related to that of the same flavoprotein from Azotobacter vinelandii. The root-mean-square difference for 932 C alpha atoms is 0.64 A, with 84% sequence identity. The residues in the active site are identical, while 89% of the interface residues are the same in the two enzymes. A few structural variations provide the basis for the differences in thermostability and redox properties between the two homologous proteins. Particularly, in the A. vinelandii molecule a threonine to alanine (T452A) mutation leaves a buried carbonyl oxygen, located at the subunit interface and in proximity of the flavin ring, unpaired to any H-bond donor, probably providing an explanation for the lower stability of the A. vinelandii enzyme with respect to the P. fluorescens enzyme. Six surface loops, which previously could not be accurately positioned in the A. vinelandii structure, are well defined in P. fluorescens lipoamide dehydrogenase. On the basis of the P. fluorescens structure, the six loops could be correctly defined also in the A. vinelandii enzyme. This is an unusual case where similar refinement methodologies applied to two crystal forms of closely related proteins led to electron density maps of substantially different quality. The correct definition of these surface residues is likely to be an essential step for revealing the structural basis of the interactions between lipoamide dehydrogenase and the other members of the pyruvate dehydrogenase multienzyme complex.