Optimal excitation and emission wavelengths to analyze amino acids and optimize neurotransmitters quantification using precolumn OPA-derivatization by HPLC

We describe an analytical methodology to obtain high sensitivity and better resolution through the study of fluorometric excitation (λex) and emission (λem) spectrum wavelengths of OPA-amino acids. The spectrum emission study revealed a maximum signal peak at 450 nm for aspartate and glutamine. For glycine, taurine, and GABA, the maximum signal peak was at 448 and for glutamate at 452 nm. The remaining amino acids analyzed showed a maximum emission around 450 nm. The best signal obtained within the spectrum excitation experiments was using 229- to 450-nm λex-λem. The drawbacks observed at these wavelengths were a baseline drift and negative peaks occurrence. Thus, the excitation wavelength of 240 nm was chosen (240- to 450-nm λex-λem) as a compromise between a very good signal response and a baseline stability to resolve the 18 amino acids studied. Furthermore, this protocol was properly validated. On the other hand, the elution gradient program used for neuroactive amino acids (aspartate, glutamate, glycine, taurine and GABA) showed separation to the baseline, in a 15-min run in all of them. Other amino acids, up to 18, also exhibited a very good separation in a 25-min run. In conclusion, we propose the use of 240- to 450-nm λex-λem wavelengths, in OPA-amino acids analysis, as the most suitable protocol to obtain the best signal response, maintaining an optimum chromatographic resolution.

Comparison of fluid compartments and fluid responsiveness in septic and non-septic patients

Our objective was to study the response to a fluid load in patients with and without septic shock, the relationship between the response and baseline fluid distributions and the ratios of the various compartments. A total of 18 patients with septic shock and 14 control patients without pathologies that increase capillary permeability were evaluated prospectively. We used transpulmonary thermodilution to measure the extravascular lung water index, intrathoracic blood volume index and pulmonary blood volume. For the measurement of the initial distribution volume of glucose, plasma volume and extracellular water we used dilutions of glucose, indocyanine green and sinistrin respectively. Transpulmonary thermodilution and dilutions of glucose were repeated 75 minutes after the beginning of the fluid load. The patients in the septic group had higher volumes of extracellular water (median 295 vs. 234 ml/kg, P < 0.001), lower intrathoracic blood volume index (median 894 vs. 1157 ml/m2, P < 0.003), higher pulmonary permeability ratios (extravascular lung water/pulmonary blood volume) (P < 0.003) and higher systemic permeability ratios (interstitial/plasma volume) (P < 0.04). The intrathoracic blood volume index increase after fluid loading was lower in the septic group (10 vs. 145 ml/m2). The pulmonary permeability ratios did not correlate with the systemic permeability ratios, and in the septic group, the percentage volume retained in the intrathoracic blood volumes after fluid loading did not correlate with the systemic permeability ratios. Septic shock can cause a redistribution of fluids. Fluid administration in these patients produced a minimal increase in intrathoracic blood volume, and the percentage of volume retained in this space was not correlated with the interstitial/plasma volume ratio.

A study of risk factors for hypospadias in the Rhône-Alpes region (France)

OBJECTIVE

Hypospadias is one of the most common congenital urogenital malformations in males with a significantly increasing incidence over the past 20 years. The causes of this insufficient virilization of the genital tubercle are essentially unknown.

SUBJECTS AND METHODS

A hospital-based controlled study was realized with 225 hypospadias cases at Debrousse Hospital, Lyon, using a detailed questionnaire completed during a consultation with the patients' parents and those of controls of the same age. The chi(2), the P-value, the odds ratios and the 95% confidence interval were assessed.

RESULTS

Hypospadias was found to be positively associated with genetic factors (as defined by the presence of other case(s) in the family in one case in four) and with neonatal low birth weight, fair-haired boys, maternal history such as viral infection during the first trimester, order of parity, toxaemia of pregnancy, delivery modality such as caesarean section, and environmental pollution.

CONCLUSIONS

These results show that aetiological factors of hypospadias are likely to be related to three main fields which interact: genes, the placenta and environmental factors.