Fine structural survey of old cuticle degradation during pre-ecdysis in two European Atlantic crabs.

Light and transmission electron microscopy were used to monitor changes due to the degradation of the old exoskeleton and related events in the sclerites, articular membranes, and gills of two decapod crustaceans (Carcinus maenas and Macropipus puber) during pre-ecdysis. In both sclerites and articular membranes, degradation follows a similar general pattern in both crab species, while the gill cuticle appears unaltered. In early pre-ecdysis (D(0)), the degradation of the old cuticle starts with the secretion of ecdysial droplets by the epidermis.

Effect of ophthalmic viscosurgical devices on lens epithelial cells: a morphological study.

Purpose: To investigate the morphological effects of Viscoat (sodium hyaluronate 3.0%-chondroitin sulfate 4.0%) on lens epithelial cells (LECs).

Characterization of the primary sonic muscles in Carapus acus (Carapidae): a multidisciplinary approach.

Sound production in carapid fishes results from the action of extrinsic muscles that insert into the swim bladder. Biochemical, histochemical and morphological techniques were used to examine the sonic muscles and compare them with epaxial muscles in Carapus acus. Sonic fibres are thicker than red and thinner than white epaxial fibres, and sonic fibres and myofibrils exhibit an unusual helicoidal organization: the myofibrils of the centre are in a straight line whereas they are more and more twisted towards the periphery.

Does sulphide detoxication occur in the gills of the hydrothermal vent shrimp, Rimicaris exoculata?

Ultrastructural observations of the gills of the hydrothermal vent shrimp Rimicaris exoculata reveal that the epithelial cells contain numerous mitochondria clustered around unusual organelles (diameter of 0.7 to 2.5 microns) containing membrane stacks.

Glycoproteins from the cuticle of the Atlantic shore crab Carcinus maenas: I. Electrophoresis and Western-blot analysis by use of lectins.

The protein and glycoprotein content of four different neutral or acidic solvent extracts (0.5 M KCl, 10% EDTA, 0.1 N HCl, or 2% acetic acid) from the mineralized exoskeleton of a decapod crustacean, the Atlantic shore crab Carcinus maenas, were characterized by quantitative analysis of proteins, SDS-PAGE analysis, and probing with lectins on blots.

Preparation of poly(D,L-lactide) nanoparticles assisted by amphiphilic poly(methyl methacrylate-co-methacrylic acid) copolymers.

When co-precipitated with amphiphilic copolymers from DMSO, poly(D,L-lactide) (PLA) can be readily converted into stable sub-200 nm nanoparticles by addition of an aqueous phase, free of any polymeric stabilizers such as poly(vinyl alcohol) or Poloxamer. In this work, the ability of random poly(methyl methacrylate-co-methacrylic acid) copolymers (PMMA-co-MA) to stabilize PLA nanoparticles was demonstrated, and the properties of PLA/PMMA-co-MA nanoparticles were investigated. When co-precipitated with PMMA-co-MA, PLA was totally converted into nanoparticles using a polymer concentration in DMSO (Cp) below 17.

Human periodontal ligament fibroblast behavior on chemically conditioned dentine: an in vitro study.

Background: Chemical root conditioning is widely used in an attempt to improve the outcome of regenerative periodontal surgery, but its effect on connective tissue cell proliferation and biosynthetic activity has been poorly studied. The goal of the present study was to test in vitro the consequences of conditioning human dentine by citric acid or minocycline on the behavior of attached human periodontal ligament (HPDL) cells in terms of proliferation, protein synthesis and morphological appearance.

Methods: HPDL cells were seeded on powdered human dentine, either untreated or conditioned for 3 minutes with 3% citric acid or 2.

Immunocytochemistry of lipids: chemical fixatives have dramatic effects on the preservation of tissue lipids.

We report here the effects of chemical fixatives on lipids studied under conditions simulating the immunogold labelling of phosphatidylserine. Using anti-phosphatidylserine antibodies, it is shown that the labelling intensity of a phosphatidylserine/phosphatidylcholine coating depends largely on the conditions of fixation. In fact, the usual aldehydic fixatives washed out most of the phostphatidylserine, thus preventing the binding of anti-phosphatidylserine antibodies.

Microencapsulation of erythromycin and clarithromycin using a spray-drying technique.

Previous methods of microencapsulation are unable to process particles smaller than 100 microm without organic solvents or the use of multistep processes. The present study investigates the feasiblity of a one-step spray-drying process to microencapsulate erythromycin and clarithromycin, antibiotics known to have an unpleasant, bitter taste. Mixtures of clarithromycin (5% by weight) or erythromycin (30% by weight) with a biodegradable polymer were prepared and spray-dried under specific conditions of temperature and turbine speed.

In vitro stimulation of human gingival epithelial cell attachment to dentin by surface conditioning.

Background: Chemical root conditioning is widely used to improve the outcome of regenerative periodontal therapies by favoring the attachment of the regenerated periodontal structures. Although the effect of root conditioning on periodontal mesenchymal cells is well documented, very little is known about its potential effect on the re-formation of the junctional epithelium, a crucial event for the protection of the wound. The goal of the present study was to test in vitro the consequences of dentin conditioning with citric acid or minocycline on the attachment kinetics and morphology of human gingival keratinocytes (HGK).

Comparison between the natural postnatal maturation and the spermine-induced maturation of the rat intestine.

In the suckling rats, orally provided spermine induced structural and biochemical changes in the intestine, which are characteristics of the postnatal maturation. This induced maturation was compared to that occurring spontaneously. Eight mumol spermine were administered orally once a day, for one or three days, to suckling rats which were 11 days old at the beginning of the experiment.

In vitro modulation of human gingival epithelial cell attachment and migration by minocycline-HCL.

Although the influence of tetracyclines on periodontal connective tissue cells has been the topic of many in vitro and in vivo studies, data regarding their effects on gingival epithelial cells are scarce. The present in vitro study was designed to examine the influence of minocycline, a semi-synthetic analog of tetracycline, on human gingival keratinocyte (HGK) attachment and migration. Attachment tests were performed with HGK prelabeled by tritiated amino-acids.

"Exolysosomes," enzyme-containing vesicles in the ecdysial space of molting crabs.

Free vesicle-like bodies (VLBs) present in the ecdysial space of cuticle regions undergoing degradation during preecdysis of the Atlantic shore crab Carcinus maenas have been interpreted either as infectious organisms or as secretion structures associated with degradation of the old cuticle. Ultrastructural, cytochemical, and immunocytological investigations were performed to test these hypotheses and to see whether VLBs are peculiar to this crab species. Similar VLBs were systematically found in two other preecdysial crabs, Cancer pagurus and Macropipus puber.

Scintigraphic visualization of intrathecal liposome biodistribution.

Background: Liposomes containing local anaesthetics have been administered intrathecally and in the epidural space. Poor attention has been given to the pharmacokinetics of liposomes as drug carriers. Therefore, we observed the biodistribution of liposomes after intrathecal injection in rats by scintigraphic imaging during 24 h.

Cytochemical investigations on tunic morphogenesis in the sea peach Halocynthia papillosa (Tunicata, Ascidiacea) 2: demonstration of proteins.

In a previous paper, cellulose fibres were demonstrated in the larval, the metamorphosing, and the juvenile tunics. In this paper we used cytochemical methods and X-ray microanalysis to obtain additional information on tunic morphogenesis in Halocynthia papillosa. The chemical composition of the tunic evolves with its structural complexity.

Cytochemical investigations on tunic morphogenesis in the sea peach Halocynthia papillosa (Tunicata, Ascidiacea). 1: demonstration of polysaccharides.

The distribution of carbohydrates was demonstrated in the embryonic, larval, and juvenile tunics of Halocynthia papillosa. An enzyme-gold marker (cellobiohydrolase-Au) was used to identify cellulose on ultrathin sections. This is the first time this biopolymer has been detected in the embryonic or larval tunic of an ascidian.

99mTechnetium-stannous oxinate as marker of liposome formulations.

Liposomes associated with tin(II) dioxinate were prepared from egg yolk phosphatidylcholine and cholesterol as sterile and pyrogen-free multilamellar or unilamellar vesicles. Complexing of liposomal tin(II) dioxinate with 99mTc attained 98% of the added radioactivity. Thirty percent 99mTc were released during 24-h incubation in biological fluids.

Ultrastructural modifications in cultured fetal quail hepatocytes exposed to pesticides and PCBs.

There is increasing interest in cultured hepatocytes as a tool for solving toxicological and pharmacological problems while reducing laboratory animal experimentation. In the present study, fetal hepatocytes from the Japanese quail (Coturnix coturnix japonica) were used as an in vitro alternative model for evaluating the effects of PCBs and various pesticide-type chemicals on cell ultrastructure. Major alterations were demonstrated.

Biodistribution of liposome-associated bupivacaine after extradural administration to rabbits.

After one extradural injection of 0.25% bupivacaine 0.3 ml and 3H-bupivacaine 0.

Biodistribution of liposomes after extradural administration in rodents.

We have mapped over 24 h the biodistribution of 99mTc-labelled multilamellar and small unilamellar liposomes in rabbits and rats by scintigraphic imaging after extradural injection. Multilamellar vesicles formed a depot at the site of injection; small unilamellar vesicles spread immediately along the extradural space and entered the systemic compartment 30 min after injection. Well-delineated liver and kidney labellings were seen after 24 h.

Immunogold labelling of fatty acyl chains.

For the first time, antibodies against a hydrophobic hapten have been used for immunogold labelling of a lipid antigen (BSA-C18:1 conjugate) coated on polystyrene. The labelling was visualised either directly in transmission electron microscopy or in light microscopy after silver enhancement. Good recognition of the fatty acyl chain was obtained even after treatment of the antigen coat with various cross-linking fixatives used for electron microscopy, i.

Cytotoxic effects of Aroclor 1254 on ultrastructure and biochemical parameters in cultured foetal rat hepatocytes.

The cytotoxicity of a commercial PCB mixture, Aroclor 1254, was assessed on cultured foetal rat hepatocytes. Under control conditions, dexamethasone stimulates immature hepatocytes to differentiate into both hepatocytes and biliary epithelial cells. Consequently, foetal rat hepatocytes maintain, in vitro, a liver-like organization with spaces corresponding to the lumen of biliary canalicules, many mitochondria, and a well-developed rough endoplasmic reticulum (RER).

Expression and induction of drug-metabolizing enzymes in cultured fetal rat hepatocytes.

An in vitro experimental model, fetal rat hepatocytes in culture, was metabolically characterized. Several enzymatic activities were expressed in these hepatocytes, namely, testosterone hydroxylations. Hepatocytes cultured up to 3 weeks in the presence of dexamethasone and phenobarbital still expressed some drug-metabolizing enzyme activities (e.

Use of cultured hepatocytes as an alternative method to study the effects of PCBs on living organisms.

In order to study the mechanism of action of polychlorinated biphenyls (PCBs) several parameters have been monitored in cultured foetal rat and quail hepatocytes. At low concentrations, the PCB mixture tested (Aroclor 1254) did not affect the biological and morphological parameters studied. Above 170 mug/ml, Aroclor induced cytotoxic effects and morphological damage, similar to those that have been observed in vivo, in both animal species (i.