We have determined the comparative activities of peroxisomal proliferators, ciprofibrate and clofibric acid on various hepatic parameters associated with endoplasmic reticulum, mitochondria and peroxisomes in primary cultures of rat hepatocytes. We have measured the activities of carnitine acetyltransferase and fatty acylCoA oxidase, and the amount of 60 and 80 kD polypeptides as biochemical markers of the peroxisomal function; laurate hydroxylase and cytochrome P-450 as markers of the endoplasmic reticulum; and carnitine palmitoyltransferase as a marker of mitochondria in primary cultures of hepatocytes. Ciprofibrate (0.01 to 0.3 mM) and clofibric acid (0.1 to 3 mM) produced similar changes in several components of cultured hepatocytes within 72 hr. Increases of protein (18 and 11%), carnitine palmitoyltransferase (23 and 97%), cytochrome P-450 (37 and 49%), carnitine acetyltransferase (484 and 614%), fatty acylCoA oxidase (529 and 931%) and laurate hydroxylase (624 and 671%) were obtained in hepatocytes after a 72-hr exposure to 0.1 mM ciprofibrate and 1.0 mM clofibric acid, respectively. In cultured hepatocytes, ciprofibrate was about 30-fold more active than clofibric acid for the stimulation of carnitine acetyltransferase, laurate hydroxylase and fatty acylCoA oxidase activities. Ciprofibrate was also more potent than clofibric acid as an inducer of the 60 and 80 kD proteins in hepatocytes. The maximal drug-induced increases in carnitine acetyltransferase activity were not additive, and the induction of carnitine acetyltransferase by ciprofibrate was blocked by addition (1 micrograms per ml) of cycloheximide or actinomycin D. Changes in protein and RNA synthesis preceded the drug-induced increases of carnitine acetyltransferase activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetyltransferases↗

PubMedDate not supplied

Tumoral calcinosis.

Tumoral calcinosis is an interesting clinical entity. It is not uncommon in certain countries. We report our experience with 22 patients with this condition seen over a 7-year period and review in detail the modalities of clinical presentation, theories of etiogenesis, histological appearances, and treatment modalities.

Adult↗

PubMedDate not supplied

In vivo cytogenetic studies on mice exposed to ethylene dibromide.

The pesticide, ethylene dibromide (EDB), was evaluated with in vivo cytogenetic assays to determine its genotoxicity. CD1 male mice were exposed to EDB through intraperitoneal injections. Bone marrow cells isolated from femora were analyzed for sister-chromatid exchange (SCE), chromosome aberration and micronucleus formation. The results showed that only certain concentrations of EDB tested caused a slight but significant increase in SCEs and chromosome aberrations. However, these increases were not dose-related. No increase in the polychromatic erythrocytes with micronuclei was observed following EDB exposure. Also, EDB did not cause cell-cycle delay in comparison with controls. Thus, it appears that EDB is not an effective genotoxic agent in vivo in mice.

Animals↗

PubMedDate not supplied

Comparative in vivo and in vitro genotoxicity studies of airborne particle extract in mice.

The genotoxicity of an acetone extract of locally collected airborne particles was evaluated both in vitro and in vivo using the sister-chromatid exchange (SCE) assay in mice. At the highest concentration (5.36 mg/5 ml culture), the extract caused approximately a 3-fold increase in SCEs over controls in mouse bone marrow and spleen primary cells in vitro. However, the same airborne particle extract did not induce a significant increase in the SCE level over controls in vivo in mouse bone marrow and spleen cells when administered intraperitoneally or through oral gavage. This indicates that bone marrow and spleen primary cell cultures can be used in in vitro genotoxicity studies of complex mixtures, and that the genotoxicity of airborne particles detected in the in vitro system cannot always be detected in vivo with the same cell types. In addition, the same acetone extract of airborne particles caused dose-related his+ revertants in the strain TA98 of Salmonella typhimurium, both with and without S9 activation. The significant finding of this study is that the in vitro genotoxicity results of airborne particle extract may not be very meaningful in an in vivo situation.

Air Pollutants↗

PubMedDate not supplied

Comparative mouse micronucleus evaluation in bone marrow and spleen using immunofluorescence and Wright's Giemsa.

Bone marrow and spleen toxicity, clastogenicity and aneugenicity were analyzed in the CD1 mouse using an antikinetochore antibody (AKA) procedure (Krishna et al., Mutation Res., 282, 159-169, 1992). Further, to verify the fluorescence micronucleus (MN) analysis, additional slides were stained with Wright's Giemsa and results were compared. 5 mice per sex were treated with cyclophosphamide (CP) (40 mg/kg) or vincristine (VC) (0.1 or 0.2 mg/kg). Slides were prepared 24 h postdose using a column fractionation procedure. Per animal, 400 total erythrocytes (TEs) for toxicity and 2000 polychromatic erythrocytes (PCEs) for MN per tissue were analyzed. In the fluorescent method, the clastogen, CP, produced MNPCEs predominantly devoid of kinetochores (K) and the aneugen, VC, produced mostly MNPCEs containing K. The MNPCE frequency did not differ significantly between tissues; however, it differed statistically between sexes. On an overall basis, spleen had significantly lower PCE to TE ratios compared to bone marrow. In general, CP and VC caused a small, but statistically significant decrease in PCE frequencies compared to controls, suggesting possible toxicity to these tissues at the given doses. The data on Wright's stain indicated that the proportion of PCEs and MNPCEs in general, were comparable to those using fluorescent stain. This study further confirms the usefulness of an AKA-staining technique in a multiple genetic endpoint evaluation under a single set of microscopic conditions.

Animals↗

PubMedDate not supplied

Anesthetic considerations for ophthalmic surgery in the pediatric patient.

In conclusion our review of 2,187 ophthalmic procedures revealed that even the very young pediatric patient can be anesthetized safely by adhering to basic principles and meticulous attention to detail.

Anesthesia, General↗

PubMedDate not supplied

Improving emulsification efficacy of lecithin by formulation design. I: Effect of adding a secondary surfactant.

The objective of this study was to seek improvement in the emulsification efficacy of lecithin by formulation design. A Base Emulsion was developed containing lecithin as the primary emulsifier. The lecithin concentration and method of preparation of the Base Emulsion were optimized to obtain minimum particle size and creaming of the emulsion. Selected hydrophilic and hydrophobic synthetic surfactants were evaluated as secondary emulsifiers for their ability to reduce particle size of the Base Emulsion. The selection of type and concentration of the secondary emulsifier was done by application of the HLB method. The hydrophilic emulsifiers selected were Tween 80, Tween 20, Pluronic F68, and Pluronic F127. The hydrophobic surfactants studied included Span 20, Span 80, Pluronic P103, and Pluronic P123. The median droplet size of the Base Emulsion was 2.7 microns. Addition of the hydrophilic emulsifiers caused an increase in particle size and substantial creaming of the emulsions. Addition of three of four hydrophobic surfactants resulted in particle size reduction, but the emulsions showed substantial creaming. Span 20 was found to be the most effective secondary emulsifier. The median particle size of the emulsion was 1.7 microns. These results suggest that supplementing the hydrophilic attributes of lecithin with an appropriate type and amount of hydrophobic surfactant improves the emulsion properties by applying principles of formulation design.

Chemistry, Pharmaceutical↗

PubMedDate not supplied

A novel self emulsifying parenteral drug delivery system.

The application of three polyhydroxy alcohols for improving parenteral emulsion formulations was investigated. A mixture of lecithin, as the primary emulsifier, and Span 20 as the secondary emulsifier, was used as the emulsifier system. The polyhydroxy alcohols selected were glycerol, propylene glycol and sorbitol. Soybean oil-in-water emulsions were prepared with the addition of increasing concentrations of each polyhydroxy alcohol. It was found that anhydrous mixtures of oil, surfactants and 30% or higher concentration of glycerol formed self emulsifying isotropic liquids, suitable for preparing Parenteral Self Emulsifying Drug Delivery Systems (PSEDDS). Spontaneous emulsification to submicron particle size of 0.4 micron occurred when these isotropic liquids were gently mixed with water. A PSEDDS formulation, containing 0.5% lidocaine, as the model drug showed similar spontaneous emulsification with particle size of 0.39 micron. Formulations containing propylene glycol, or sorbitol or lower concentrations of glycerol did not form self emulsifying mixtures. There were substantial differences in the particle size reduction pattern with each polyhydroxy alcohol. Glycerol was most effective, with minimum particle size obtained at 30% concentration. Addition of propylene glycol resulted in minimum particle size at 60% concentration. But there was increase in particle size at higher concentrations. Sorbitol was not very effective in reducing particle size. Alteration of the surfactant phase distribution at the interface was found to be the primary effect of polyhydroxy alcohols.

Drug Delivery Systems↗

PubMedDate not supplied

Effect of lyophilization on parenteral emulsions.

The feasibility of preparing lyophilized anhydrous products, for reconstitution in to emulsion dosage forms was investigated. Stable soybean o/w emulsions were prepared using a mixture of lecithin and Span 20 as the emulsifiers. Two series of emulsions were prepared for this study, each containing a polyhydroxy alcohol as a consurfactant for particle size reduction. Increasing concentrations of glycerol (10-30% w/w) were added to one group of emulsions and propylene glycol (20-60% w/w) was added to the second group of emulsions. All formulations were found to have good particle size stability. The emulsion formulation containing 30% glycerol could be successfully lyophilized into an anhydrous product. Reconstitution of this lyophilized product resulted in an emulsion essentially similar to the original emulsion prior to lyophilization. This is because the mixture of the oil phase and 30% w/w glycerol formed a self-emulsifying system. All other emulsion formulations were not suitable for lyophilization. These formulations cracked during lyophilization, separating into an upper oil layer and a lower layer of the continuous phase. The formation of an upper oil layer prevented complete drying of these emulsions. The particle size of these lyophilized emulsions, when reconstituted with the external phase was greater than the emulsion particle size prior to lyophilization. But the change in particle size was less with increasing concentrations of polyhydroxy alcohols. These results indicate that emulsions can be lyophilized to prepare a product suitable for reconstitution to a parenteral emulsion dosage form provided the formulation is designed to withstand temperature and phase changes during the lyophilization process.

Emulsions↗