Soluble calcium/SMFP dentifrice: effect on enamel fluoride uptake and remineralization.

PURPOSE: To evaluate in situ the effect of soluble calcium on fluoride uptake and remineralization by human dental enamel from a sodium monofluorophosphate (SMFP) dentifrice. MATERIALS AND METHODS: Eight volunteers took part in this cross-over, double-blind design study performed in three phases of 45 days. During each phase of the experiment, the subjects wore an acrylic resin appliance containing four blocks of human dental enamel with artificial caries to evaluate fluoride uptake and remineralization by three dentifrices: SMFP containing CaCl2, SMFP, and placebo. After each phase, the enamel blocks were removed and the total fluoride uptake (ppm F) and microhardness (Knoop) were measured. Statistical analyses (ANOVA and Turkey's test) were done. RESULTS: There was no statistically significant difference between SMFP-CaCl2 and SMFP treatments regarding the amount of fluoride and microhardness data of treated enamel blocks as well as their areas under the curves, although both differed significantly (P < 0.05) when they were compared with placebo. However, the SMFP-CaCl2 treatment demonstrated the highest values on fluoride uptake and microhardness data. Furthermore, the microhardness data demonstrated 50% and 40% of remineralization for SMFP-CaCl2 and SMFP dentifrices, respectively.

Laparoscopy and thoracoscopy in evaluation of abdominal trauma.

The role of laparoscopy and thoracoscopy as diagnostic modalities in blunt and penetrating abdominal trauma was studied in 35 hemodynamically stable patients who otherwise would have undergone exploratory laparotomy because of equivocal diagnostic findings. Minimally invasive laparoscopic techniques (single 5 millimeter port) and minimal abdominal insufflation (8-10 millimeters mercury) were used with general anesthesia. Both laparoscopy and thoracoscopy appear to be safe (no complications), highly sensitive (100%), specific (88%), and accurate (91%) tools for determining the presence of surgically significant abdominal pathology and the need for therapeutic laparotomy. The appropriate application of these techniques, possibly under local anesthesia, offers potential cost savings.

Immunofluorescent detection of nuclear double-stranded RNA in situ in Vero and mosquito cells.

Double-stranded RNA (dsRNA) was detected in situ by indirect immunofluorescence with antibodies to dsRNA. It was seen in nuclei of Vero and Aedes albopictus cells, but not in BHK cells, KB cells, chick embryo fibroblasts, or HeLa cells. Reactive dsRNA was present in the nucleoplasm, but not in nucleoli or cytoplasm. Extracted RNA from the whole cell contained from 0.08 percent (BHK) to 0.46 percent (HeLa) dsRNA, as estimated by serological methods. This dsRNA, found in molecules having the size distribution of heterogeneous nuclear RNA, did not renature rapidly after denaturation. The quantity of dsRNA in total extracted RNA did not correlate with the presence or absence of nuclear staining in situ.

Pulmonary insufficiency produced by isoproterenol.

Twelve healthy, anesthetized, mechanically ventilated dogs received an infusion of isoproterenol hydrochloride, 0.1 microgram per kilogram for two hours. There was a rapid and statistically significant increase in the pulmonary shunt, cardiac output and mean pulmonary artery pressure; a significant decrease in the pulmonary vascular resistance, and no significant change in the pulmonary artery wedge pressure. These findings support those of previous studies which demonstrated the beta adrenergic stimulation is important in the pathogenesis of pulmonary insufficiency. The shunt results from ventilation-perfusion inequalities produced by the increased pulmonary blood flow and pulmonary vasodilatation. Because of the production of pulmonary insufficiency, isoproterenol or other beta adrenergic agonists should be used with caution in the critically ill, who often have or may develop the respiratory distress syndrome.

Effect of alpha and beta adrenergic blockade on epinephrine induced pulmonary insufficiency.

Recent studies demonstrated that epinephrine causes significant pulmonary A-V shunting. This study reports the effect of alpha and beta adrenergic blockade on this shunting. Sixty-three anesthetized mongrel dogs were ventilated with a mechanical respirator. Measurements of (1) the pulmonary shunt, (2) cardiac output, (3) mean pulmonary artery, pulmonary capillary wedge and systemic pressures, and (4) pulmonary and systemic vascular resistances were obtained at 5, 15 and 30 minute intervals during the first hour and hourly for 5 hours. Fifteen dogs received no treatment. All others received epinephrine hydrochloride, 2 mug/kg/min for 5 hours. Ten received epinephrine only. Ten were pretreated with propranolol hydrochloride, 250 mug/kg, 12 with phenoxybenzamine, 1 mg/kg, and 16 with phenoxybenzamine and propranolol. Propranolol significantly decreased the epinephrine induced pulmonary shunt at all times and was the most effective drug. Phenoxybenzamine decreased the early shunting, but less than propranolol, and did not decrease the late shunting. Blockade with propranolol and phenoxybenzamine was less effective than propranolol alone. Based on the observed hemodynamic changes it was suggested that beta blockade is effective in reducing epinephrine induced pulmonary insufficiency by favorably altering the flow and distribution of pulmonary blood flow which in turn decreases epinephrine induced ventilation-perfusion inequalities and capillary hypertension both of which result in shunting. Conversely phenoxybenzamine has an unfavorable effect on the pulmonary flow. These studies support previous work in animals and man which showed that beta adrenergic stimulation is important in the pathogenesis of pulmonary insufficiency. Because the amounts of epinephrine used produce blood levels observed in critical illness, these studies add support to a relationship between the increased catecholamine stimulation of critical illness and the associated and often unexplained pulmonary insufficiency.