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Biomedical subjects

P DeLuca

Publications and source records attributed to P DeLuca.

8 recordsLinked to original sources
PubMed1986

Binding of insulin to a continuous ambulatory peritoneal dialysis system.

The binding of insulin in two peritoneal dialysis solutions to polyvinyl chloride dialysate containers and an administration set and the effect of adding antibiotics to the dialysate solutions were studied in a simulated continuous ambulatory peritoneal dialysis (CAPD) system. Using a radiotracer method, binding of insulin to dialysate containers was determined at various times up to 48 hours after addition of 10, 20, 40, and 80 units of insulin each to 2 L of either 1.5% or 4.25% dextrose dialysate solution. The method was repeated in 1-L glass containers. Each of the dialysate solutions was then passed through a CAPD administration set to determine binding to the set's cellulose-ester membrane filter. In another experiment to simulate binding to the set in actual practice, three bags of 1.5% dextrose dialysate were alternately infused with one bag of 4.25% dextrose dialysate through a single CAPD set until eight bags of dialysate containing insulin 40 units were given over 48 hours. The ability of gentamicin sulfate and cephalothin sodium to release bound insulin from the CAPD filter was determined by passing 2 L of each dialysate solution containing either gentamicin 60 mg or cephalothin 500 mg through the set over an 18-minute period. The binding of these antibiotics to the dialysate bags was also studied using high-performance liquid chromatography assays. Insulin binding to the bag increased with increasing insulin concentration and length of storage in the bag; binding was not significantly different between the two dialysate solutions except at the 80-unit/2-L concentration. Binding in glass containers was less than that in polyvinyl chloride bags.(ABSTRACT TRUNCATED AT 250 WORDS)

Anti-Bacterial Agents↗
PubMed1979

Sepsis in rabbits following administration of contaminated infusions through filters of various pore sizes.

The effects of three final filter pore sizes on sepsis and survival times in rabbits infused with contaiminated intravenous fluids were compared. Intravenous fluids were administered for up to 12 hours to five groups of rabbits. Groups 2, 3 and 4 received fluids, contaminated with Gram-negative rods, that were filtered with 0.22-, 1.0- and 5.0-micrometers filters, respectively. Rabbits in Groups 1 and 5 received uncontaminated and contaminated fluids, respectively, neither of which was filtered. Cultures were taken of blood and of fluid below the filters, and rabbit survival times were recorded. At 6, 8 and 12 hours, Group 2 survival time was not significantly different from that of the negative control; the survival times for Groups 3, 4 and 5 were significantly less than for the negative control. Fluid and blood cultures of Group 2 were negative or statistically indistinguishable from those of Group 1. Cultures for Groups 3, 4 and 5 were positive. The study suggests that 1.0- and 5.0-micrometers inline final filters have no beneficial effect on survival following infusion of contaminated fluids, but that 0.22-micrometer inline final filters increase survival time.

Animals↗
PubMed1977

Effect of inline filtration on the potency of drugs administered intravenously.

The binding of cephalothin sodium, phenobarbital sodium, dexamethasone sodium phosphate, isoproterenol hydrochloride, digoxin, dactinomycin and phenytoin sodium to three intravenous inline filters--a 5-micrometer stainless steel depth filter, a 0.2-micrometer cellulose ester membrane and a 0.2-micrometer polycarbonate membrane--was studied. The experiments were conducted simulating inline i.v. filtration of these drugs in three i.v. solutions--lactated Ringer's, 5% dextrose and normal saline. Cephalothin was assayed colorimetrically, phenobarbital and phenytoin spectrophotometrically, and the other drugs by radiotracer technique. Binding of the drugs to the filter was found to be insignificant from a therapeutic standpoint, except for dactinomycin which bound to the 0.2-uicrometer filters. The binding of dactinomycin was approximately 13% of the amount administered through cellulose ester and polycarbonate membranes, respectively. The binding occurred during the initial period of filtration of the drug solution. It was concluded that inline filtration of drugs administered in relatively high does should not present any problem concerning the reduction of the therapeutic potency because of filtration.

Cephalothin↗
PubMed1976

Correlation of dielectric constant and solubilizing properties of tetramethyldicarboxamides.

The dielectric constants of aqueous solutions of four tetramethyldicarboxamides (tetramethylpimelamide, tetramethylsuberamide, tetramethylazelamide, and tetramethylsebacamide) were measured at 25 degrees. The values obtained were utilized in assessing the solubility behavior patterns of glutethimide, a semipolar, water-insoluble drug in these amide-water systems. At equimolar concentrations of water-rich amide solutions, the solubilizing power paralleled the chain length of the amides. The higher homologs appeared to favor more extensive solvation, as shown by the lower dielectric constants of their resulting solutions. Deviation in solubilizing action between the odd-carbon amides and the even-carbon amides, however, was exhibited at higher amide concentrations. The two odd-carbon amides, tetramethylpimelamide and tetramethylazelamide, showed consistently greater solubilizing action. This phenomenon was attributed to the greater association tendencies of the odd-carbon amides with water, which effectively reduced self-associations of glutethimide.

Amides↗
PubMed1976

Residues in antibiotic preparations, ii: effect of pH on the nature and level of particulate matter in sodium cephalothin intravenous solutions.

The effect of pH on the extent and nature of particulate contamination in sodium cephalothin intravenous solutions was studied. The extent of particulate contamination was determined by microscopic and automatic electronic counting procedures, and the physical nature of the particles was determined using scanning electron microscopy. At low pH values (i.e., 4.9--5.9), an amorphous residue was predominant, while at higher pH values (6.9--7.8), the gelatinous nature of the residue disappeared and small crystalline particulates of varying sizes were predominant. The level of particulate contamination (particles over 10 mum in size) decreased with an increase in pH to a minimum level between pH 7 and 8. Advice is given to practitioners regarding the preparation of sodium cephalothin solutions.

Cephalothin↗
PubMedDate not supplied

A beam intensity monitor for the Loma Linda cancer therapy proton accelerator.

A beam intensity monitor was tested in a 230-MeV proton beam at the Loma Linda Proton Therapy Accelerator during its commissioning at Fermi National Accelerator Laboratory. The intensity monitor was designed to regulate the beam intensity extracted from the proton synchrotron. The proton beam is tunable between 70 and 250 MeV with an adjustable intensity between 10(10) and 10(11) protons per spill. A beam spill is typically 1 s long with a 2-s repetition period. The intensity monitor must be radiation hard, expose minimum mass to the beam, and measure intensity to 1% in 1-ms time intervals. To this end, a 5-cm-thick xenon gas scintillator optically coupled to a photomultiplier tube (PMT) was tested to measure its response to the proton beam. The gas cell was operated at 1.2 atm of pressure and has 12.7-microns-thick titanium entrance and exit foils. The total mass exposed to the beam is 0.14 g/cm2 and is dominated by the titanium windows. This mass corresponds to a range attenuation equal to 1.4 mm of water. The energy lost to the xenon gas is about 70 keV per proton. Each passing proton will produce approximately 2000 photons. With a detection efficiency on the order of 0.05% for this UV light, one would anticipate over 10(10) photoelectrons per second. In a 1-ms time bin there will be approximately 10(7) photoelectrons. This yields a resolution limited by systematics. For unregulated 0.4-s proton spills, we observe a response bandwidth in excess of 10(4) Hz. While signal-to-noise and linearity were not easily measured, we estimate as few as 10(3) protons can be observed suggesting a dynamic range in excess of 10(5) is available.

Humans↗