Spectrofluorometric resolution of closely overlapping drug mixtures using chemometrics methods

A modified parallel factors analysis (PARAFAC) algorithm with a penalty diagonalization error (PDE), newly proposed by the present authors, was utilized to simultaneously resolve drug mixtures of propranolol (PRO), dipyridamole (DIP) and amiloride (AMI) without any loss of sensitivity. The analyses were performed in aqueous solution. The experimental results demonstrated that the profiles of the spectra and the concentrations could be accurately resolved using the PDE algorithm with a high sensitivity and stable repeatability. That is to say, the closely overlapping problem of the spectra could be easily solved. Furthermore, simultaneous determinations of three kinds of tablets, which contain PRO, AMI and DIP, respectively, were successfully performed with satisfactory results.

Catheter-related infection in infants due to an unusual lipophilic yeast--Malassezia furfur

Malassezia furfur (Pityrosporum orbiculare, P ovale), a lipophilic yeast that is part of the normal skin flora, causes tinea versicolor but has only rarely been associated with more serious infections. We report five episodes in four infants of catheter-related infection caused by this organism. All episodes occurred in infants who had survived serious neonatal disorders and were receiving prolonged therapy with intravenous fat emulsion. Sudden onset of fever without focal findings was the usual presentation; however, one afebrile patient had recurrent episodes of apnea, bradycardia, and cyanosis. Thrombocytopenia was a prominent finding. Patients were generally treated with amphotericin B. All patients recovered when the colonized catheter was removed or fat emulsion therapy was stopped. The yeast usually grew slowly in blood culture media but grew readily when subcultured onto Sabouraud's medium coated with sterile olive oil. Yeasts were readily identified in all four patients in whom a buffy coat Gram stain was obtained of blood from the central intravenous catheter. M furfur may be a fairly common but unrecognized cause of catheter-related sepsis in infants receiving long-term fat emulsion therapy. This organism should be sought whenever routine blood cultures are negative for bacteria and yeasts are observed in a buffy coat Gram stain.

Intracranial pressure. Sequential measurements in full-term and preterm infants

Intracranial pressure (ICP) was measured sequentially using a pressure-activated fiberoptic device that is placed over the anterior fontanel in 120 full-term and 53 preterm infants during the first week after birth. Mean birth weight in full-term infants was 3,527 g (range, 2,720 to 4,620 g) and in preterm infants was 1,695 g (range 1,130 to 2,440 g). Mean ICP was 12.6, 12.1, and 11.4 cm H2O on days 1,2, and 3 in full-term infants, and was 10.2, 17.0, 11.0, 8.9, 7.3 cm H20 on days 1, 2, 3, 5, 7 in preterm infants. The values in preterm infants did not seem to be related to differences in Apgar scores, but higher values were seen in infants treated with continuous positive airway pressure administered by nasal prongs (before the method of fixation was changed). More stable values have been seen recently in preterm infants, which may reflect changes in care (eg, less hypoxemia).

Amniotic fluid volume and composition following experimental manipulations in sheep

Twenty to thirty percent of amniotic fluid volume was replaced by isotonic solutions of saline, mannitol, or dextrose in chronically cannulated ovine fetuses. In all cases the sodium, potassium, and chloride concentrations returned to control values in 3 to 6 hours. Urea and creatinine behaved similarly in the saline and mannitol experiments, but rose above control values within 1 hour of dextrose replacement. Amniotic fluid volume increased with return of solute. Fetal urine drainage to the exterior abolished the rapid return of urea and creatinine concentrations in the dextrose experiments, although no changes in renal function occurred in any experiments. It was concluded that dextrose inhibited the exit of urea and creatinine from the amniotic compartment.

Excessive handling as a cause of hypoxemia

Continuous transcutaneous oxygen (TcPo2) monitoring was used to study low-birth-weight infants (15 control, 15 experimental) during their stay in the intensive care nursery (ICN). Twenty hours of continuous recordings were made of heart rate, respiratory rate, and TcPo2 in the first five days after birth. Personnel caring for the control infants were blind to the TcPo2 measurements. Those caring for the experimental group were instructed in the operation of the TcPo2 monitor and used the device to modify the timing and extent of procedures to minimize "undersirable time" (TcPo2 less than 40 or greater than 100 torr). Control group infants had an average of 40 min/20 hr in "undesirable time." When personnel used TcPo2 monitoring to modify care this "undesirable time" was reduced to 6 min/20 hr. This difference was statistically significant (P less than .001). Infants in the control group were handled more frequently, and experienced more hypoxemia. Of the hypoxemic time suffered by the control infants 75% was associated with handling. Only 5% of the hypoxemia or hyperoxemia was detected by blood Pao2 analysis or conventional monitors. Intermittent arterial blood gas sampling is an inadequate method for monitoring arterial oxygenation in low-birth-weight infants since hypoxemia and hyperoxemia are often missed. Continuous TcPo2 monitoring improves care by diminishing "undesirable time."