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[Prediction of the bacteriological quality of natural waters in urban environments. Effect of the El Niño-Southern Oscillation].

At the moment of examination, the bacteriological quality of water is not, to a large extent, more than an a posteriori evaluation: the population is advised afterwards that it had been exposed to a sanitary risk. The ideal situation for managing aquatic environments or recreational use would be to be able to predict at any moment their bacteriological quality. An approach would be to develop predictive models to relate the exceedance (number of days during which the bacteriological indicator exceeds the standards) with environmental variables. Studies were carried out at two beaches with different limnological characteristics, a fluvial beach and a lacustrine beach, from the beginning of 1998 to the end of 2000, so that it was possible to obtain information on the impact of very different hydroclimatic situations on microorganisms of sanitary interest (Escherichia coli and cyanobacteria). Three variables, maximum concentration of E. coli, rains and water level, justified 92.6% of the exceedance variance in the multiple regression model at the fluvial beach. Other abiotic variables (temperature, pH, conductivity, transparency and dissolved oxygen) showed collinearity problems or did not make statistically significant contributions to the model. During the El Niño event (gauge heights > 5 m) there were no exceedances after the rains, even with precipitations of 200 mm. Moreover, cyanobacteria density remained low (x = 1.191 +/- 0.703 log10 cian./ml). During the negative pluvial anomalies, although the exceedances of E. coli were not very frequent at both beaches due to the scarce rains, a massive development of cyanobacteria was produced (x = 4.657 +/- 0.578 log10 cian./ml) at the lacustrine beach. At this beach, the mean decay coefficient (K) for E. coli was significantly (p < 0.05) lower than that estimated for the fluvial beach (K = -0.682 +/- 0.32 versus K = -0.387 +/- 0.16, respectively), possibly due to the unfavourable environment created by the higher development of photosynthetic organisms. Analizing separately the anomalous period, variables that better explained (98.6%) the exceedances were (in addition to the maximum concentration of E. coli) pH, temperature and days without rains (DWR) before the sampling. The longest exceedances (6 to 8 days) were produced at the end of the negative pluvial anomalies, after prolonged periods (> 30 days) of droughts. Regression models obtained to predict the exceedance of E. coli were simplified using only three abiotic variables (water level, rains and DWR). Although, in this way, the percentage of explanation of the exceedance is lower (78.5%), the information needed for the model is obtained quickly and preventive measures can be carried out immediately while waiting for more information.

Argentina↗

PubMed1998

Large index-fingertip forces are produced by subject-independent patterns of muscle excitation.

Are fingertip forces produced by subject-independent patterns of muscle excitation? If so, understanding the mechanical basis underlying these muscle coordination strategies would greatly assist surgeons in evaluating options for restoring grasping. With the finger in neutral ad- abduction and flexed 45 degrees at the MCP and PIP, and 10 degrees at DIP joints, eight subjects attempted to produce maximal voluntary forces in four orthogonal directions perpendicular to the distal phalanx (palmar, dorsal, lateral and medial) and in one direction collinear with it (distal). Forces were directed within 4.7 +/- 2.2 degrees (mean +/- S.D.) of target and their magnitudes clustered into three distinct levels (p < 0.05; post hoc pairwise RMANOVA). Palmar (27.9 +/- 4.1 N), distal (24.3 +/- 8.3 N) and medial (22.9 +/- 7.8 N) forces were highest, lateral (14.7 +/- 4.8 N) was intermediate, and dorsal (7.5 +/- 1.5 N) was lowest. Normalized fine-wire EMGs from all seven muscles revealed distinct muscle excitation groups for palmar, dorsal and distal forces (p < 0.05; post hoc pairwise RMANOVA). Palmar force used flexors, extensors and dorsal interosseous; dorsal force used all muscles; distal force used all muscles except for extensors; medial and lateral forces used all muscles including significant co-excitation of interossei. The excitation strategies predicted to achieve maximal force by a 3-D computer model (four pinjoints, inextensible tendons, extensor mechanism and isometric force models for all seven muscles) reproduced the observed use of extensors and absence of palmar interosseous to produce palmar force (to regulate net joint flexion torques), the absence of extensors for distal force, and the use of intrinsics (strong MCP flexors) for dorsal force. The model could not predict the interossei co-excitation seen for medial and lateral forces, which may be a strategy to prevent MCP joint damage. The model predicts distal force to be most sensitive to dorsal interosseous strength, and palmar and distal forces to be very sensitive to MCP and PIP flexor moment arms, and dorsal force to be sensitive to the moment arm of and the tension allocation to the PIP extensor tendon of the extensor mechanism.

Adult↗

PubMed1994

Structure and transcription of an immediate-early region in the human herpesvirus 6 genome.

The unique segment of the human herpesvirus 6 (HHV-6) genome is essentially collinear to the unique long DNA segment of another betaherpesvirus, the human cytomegalovirus (HCMV). However, the HHV-6 genomic section that is analogous in position to the major immediate-early (IE) locus of HCMV does not exhibit recognizable sequence homologies. The respective HHV-6 region of 5.5 kbp is flanked on one side by 25 to 28 incomplete tandem repeats of 105 to 110 bp that contain, with one exception, a single KpnI restriction site (KpnI repeats). About 250 reiterations of the sequence motif CACATA are located on the other end. We identified two open reading frames of 375 and 2,595 nucleotides, respectively, on one strand. Strand-specific Northern blot analyses with RNA harvested from HHV-6 (strain U1102)-infected HSB-2 cells or cord blood lymphocytes revealed two transcripts of about 3.5 and 4.7 kb in the corresponding orientation. Sequence analyses of the respective cDNA clones and primer extension experiments were used to map the mRNAs. The two transcripts are coterminal and multiply spliced and code for the same putative 104.6-kDa protein, but they are initiated from different promoters. Characterization of smaller cDNA clones and Northern blotting with other strand-specific probes showed that singly spliced mRNAs of 1.0 and 1.5 kb are transcribed from the opposite strand; they could code for a 17.2-kDa polypeptide. Blocking experiments with cycloheximide led to the conclusion that only the 3.5-kb mRNA is synthesized in the absence of protein biosynthesis upon infection with cell-free virus. This identifies a single IE gene of HHV-6 at the genomic position corresponding to the major IE region of HCMV, although the coding content and transcriptional regulation are quite different for these two herpesvirus IE regions.

Base Sequence↗

PubMed1997

Automated cardiac output measurement by spatiotemporal integration of color Doppler data. In vitro and clinical validation.

BACKGROUND: A new Doppler echocardiographic technique has been developed for automated cardiac output measurement (ACOM) that assumes neither a flat flow profile nor collinearity with the scan line, but clinical validation of this method is lacking. METHODS AND RESULTS: In 165 subjects (50 intensive care patients, 10 dobutamine echocardiography patients, and 105 normal volunteers; age, 49.4 +/- 19.3 years; 92 men), ACOM was performed in the left ventricular outflow tract (LVOT), with the color baseline shifted to avoid aliasing. ACOM was also tested in a pulsatile in vitro model. Stroke volume was calculated by double integration of Doppler signals in space (across the LVOT) and in time (through the systolic period), assuming hemiaxial symmetry: integral of integral of pi r v(r,t) dr dt, where v(r,t) is the velocity at a distance r from the center of the LVOT at time t during systole. Stroke volume from ACOM was compared with thermodilution (TD), aortic valve pulsed-wave Doppler (PWAO), and left ventricular echocardiographic (two-dimensional [2D]) methods. There was good correlation between ACOM and PWAO (r = .93). TD (r = .86), and 2D (r = .74), with close agreement seen. ACOM had higher correlation and agreement with TD than did either PWAO (P < .02) or 2D (P < .01). ACOM was also able to track accurately the changes in cardiac output with dobutamine infusion in comparison with PWAO (r = .94). In vitro assessment demonstrated excellent correlation (r = .98, y = 1.0x + 1.94) with little impact of pulse repetition frequency or misalignment up to 30 degrees. Gain dependency was noted but could be optimized by visual inspection of the color image. CONCLUSIONS: Automatic integration of numerical data within color Doppler flow fields is a feasible new method for quantifying flow. It is simpler and faster, requires fewer assumptions, and uses only one apical view. ACOM is a promising new approach to echocardiographic quantification that deserves further study and refinement.

Adolescent↗

PubMed2004

Daily mortality and air pollution in Atlanta: two years of data from ARIES.

Associations between daily mortality and air pollution were investigated in Fulton and DeKalb Counties, Georgia, for the 2-yr period beginning in August 1998, as part of the Aerosol Research and Inhalation Epidemiological Study (ARIES). Mortality data were obtained directly from county offices of vital records. Air quality data were obtained from a dedicated research site in central Atlanta; 15 separate air quality indicators (AQIs) were selected from the 70 particulate and gaseous air quality parameters archived in the ARIES ambient air quality database. Daily meteorological parameters, comprising 24-h average temperatures and dewpoints, were obtained from Atlanta's Hartsfield International Airport. Effects were estimated using Poisson regression with daily deaths as the response variable and time, meteorology, AQI, and days of the week as predictor variables. AQI variables entered the model in a linear fashion, while all other continuous predictor variables were smoothed via natural cubic splines using the generalized linear model (GLM) framework in S-PLUS. Knots were spaced either quarterly, monthly, or biweekly for temporal smoothing. A default model using monthly knots and AQIs averaged for lags 0 and 1 was postulated, with other models considered in sensitivity analyses. Lags up to 5 days were considered, and multipollutant models were evaluated, taking care to avoid overlapping (and thus collinear) AQIs. For this reason, PM(2.5) was partitioned into its three major constituents: SO(2-)(4), carbon (EC + 1.4 OC), and the remainder; sulfate was assumed to be (NH(4))(2)SO(4) for this purpose. Initial AQI screening was based on all-cause (ICD-9 codes <800) mortality for those aged 65 and over. For the (apparently) most important pollutants--PM(2.5) and its 3 major constituents, coarse PM mass [CM], 1-h maximum CO, 8-h maximum O(3)--we investigated 15 mortality categories in detail. (The 15 categories result from three age groups [all ages, <65, 65+] and five cause-of-death groups [all disease causes, cardiovascular, respiratory, cancer, and other "remainder" disease causes]). The GLM model outputs that were considered included mean AQI effects and their standard errors, and two indicators of relative model performance (deviance and deviance adjusted for the number of observations and model parameters). The latter indicator was considered to account for variations in the number of observations created by varying amounts of missing AQI data, which were not imputed. The single-AQI screening regressions on all-cause 65+ mortality show that CO, NO(2), PM(2.5), CM, SO(2), and O(3), followed by EC and OC, consistently have the best model fits, after adjusting for the number of observations. Their relative rankings, however, vary according to the smoothing knots used, and there is no correspondence between mean AQI effect and overall model fit.(Other regression runs often show that the best model fits are obtained with no AQI in the model.) There is no correspondence between mean AQI effect and statistical significance or between mean effect and serial correlation. There is a highly significant (.001 level) relationship between overall model fit and serial correlation; the best fitting models have the most frequent knot spacing and the most negative serial correlation. The regression analyses by cause of death find elderly circulatory deaths to be consistently associated with CO for all models.

Adult↗