Activity of "nonspecific pancreatic carboxylesterase" in rat serum in experimentally induced acute pancreatitis (preliminary results)

The aim of this study was to obtain more information on the serum level of "nonspecific pancreatic carboxylesterase" (PCE) in experimentally induced acute pancreatitis in rats. The effects of caerulein stimulation, hepatic duct ligation, bile-pancreatic duct ligation or the effect of retrograde injection of saline, 5% taurocholate and sunflower oil were investigated. The activity of PCE and amylase was measured in the serum, pancreatic tissue, pancreatic juice and ascitic fluid. The changes in PCE activity were greater (both in directions to increase or decrease) than that of amylase, produced by different experimental procedures. The results confirm the thesis that the serum activity of PCE is a more sensitive diagnostic method than that of amylase to detect the inflammatory process in the pancreas or the effect of obstruction of the pancreatic duct.     

Study of the sensitivity of the L-forms of group A Streptococcus to antibiotics in artificial nutrient media and in human cell cultures

Sensitivity of L-forms of group A streptococci to 5 antibiotics such as erythromycin, lincomycin, tetracycline, gentamicin and chloramphenicol was studied in an artificial nutrient medium and cell cultures i.e. human fibroblast diploid cells and transplantable human heart cells (Girardi). In vitro investigation of the antibiotic effect on the streptococcal L-forms revealed their sensitivity to erythromycin (MIC, 0.4 micrograms/ml), lincomycin (MIC, 0.08 microgram/ml) and tetracycline (MIC, 2 micrograms/ml). The streptococcal L-forms were slightly sensitive to gentamicin (MIC, 6 micrograms/ml) and chloramphenicol (MIC, 30 micrograms/ml). Complete inhibition of the growth of the L-forms in the Girardi cells on the 1st day of the experiment after the antibiotics administration in single doses was induced by lincomycin, 5 micrograms/ml, erythromycin, 10 micrograms/ml, and tetracycline, 100 micrograms/ml. In the diploid cells, the respective figures were 50, 100 and 200 micrograms/ml. Chloramphenicol and gentamicin had an inhibitory effect on the growth of the L-forms but produced no sanative effect.     

Ultrastructural studies of scrapie-associated fibrils and prion protein from hamster brains infected with scrapie

We report here about the purification of prion protein 27-30 (PrP 27-30) and scrapie-associated fibrils (SAF) from hamsters infected with the 263K strain of scrapie. Ultrastructural analysis of fractions from scrapie-infected brains revealed numerous fibrils measuring approximately 20 nm in diameter and 100-200 nm in length. The substructure of these fibrils consisted of protofilaments which were usually straight and rarely helically arranged. We conclude that the electron microscopic appearance of SAF depends much on the purification scheme.     

Effect of Staphylococcus aureus serine proteinase on human lymphocyte impairment

Assessment of lymphocyte surface membrane integrity by means of trypan exclusion test and longer term survival studies based on 3HTdR uptake and Con A stimulation test were used to estimate effect of Staphylococcus aureus serine proteinase on human lymphocytes in vitro. At concentration of proteinase as high as 10 micrograms/ml, the percentage of trypan-stained lymphocytes increase with enzyme level. In contrast, decrease of 3HTdR level and Con A stimulation is already apparent at concentrations of proteinase ten times lower. Autologous serum exerts strong protective effect. Observed impairment is discussed as significant for local response in inflammation.     

Tridimensional analysis of the formation of secretory vesicles in the Golgi apparatus of absorptive columnar cells of the mouse colon

The tridimensional structure of the Golgi apparatus has been studied in the absorptive cells of the mouse colon by means of reduced osmium postfixation and phosphatase cytochemistry. In thick sections of tissue impregnated with osmium tetroxide or treated with a technique to demonstrate TPPase activity, the Golgi formed a continuous ribbon-like structure capping the upper pole of the nucleus. Along the longitudinal axis of this ribbon, compact zones made up of superposed flattened saccules alternated with less compact zones which consisted of highly perforated saccules or bridging anastomosed tubules. In the cis-trans axis, the following elements were observed: (1) a cis element consisting of a continuous osmiophilic tubular network; (2) two or three subjacent elements selectively perforated by wells; (3) a trans compartment made up of two or three TPPase-reactive sacculotubular elements, some showing a "peeling-off" configuration. In some regions, the first flattened saccule of this trans compartment displayed discrete ovoid dilatations, located in compact zones and containing a dense granulofibrillar material; in the subjacent elements this material was seen concentrated in nodular swellings, at the intersection of the meshes of anastomosed membranous tubules. 100-300 nm vesicles containing a similar dense granulofilamentous material were observed in the trans Golgi zone and interspersed in the supranuclear cytoplasm between the Golgi zone and the apical surface of the cell. Smaller vesicles 80-100 nm in diameter containing a fine dusty material were also seen in proximity. These morphological observations suggested that at least two kinds of material were segregated in the saccules of the trans compartment and packaged in vesicles of two class sizes that detached from the Golgi stack on its trans aspect.     

Effects of postnatal age and diet on the fatty acid composition of plasma lipid fractions in preterm infants

Diet and postnatal age effect the fatty acid composition of plasma and tissue lipids. This work was designed as a transversal study to evaluate the changes in the fatty acid composition of plasma phospholipids, cholesteryl esters, triglycerides and free fatty acids in preterm infants (28-35 weeks gestational age), fed human milk (HM) and milk formula (MF) from birth to 1 month of life. Sixteen blood samples were obtained from cord, and 19 at 6-8 h after birth, 14 at 1 week and 9 at 4 weeks from HM-fed infants and 18 at 1 week and 14 at 4 weeks from MF-fed ones. Groups had similar mean birth weight, gestational age and sex ratio. The MF provided 69 kcal/dl and contained 16% of linoleic acid and 1.3% of alpha-linolenic acid on the total fat. Plasma lipid fractions were extracted and separated by thin-layer chromatography and fatty acid methyl esters were quantitated by gas liquid chromatography. In plasma phospholipids, linoleic acid (18:2 omega 6) continuously increased from birth to 1 month of age, but no changes were seen as related to type of diet; polyunsaturated fatty acids greater than 18 carbon atoms of both the omega 6 and omega 3 series (PUFA omega 6 greater than 18 C and omega 3 greater than 18 C) dropped from birth to 1 week and continued to decrease in MF-fed infants until 1 month; eicosatrienoic (20:3 omega 6), arachidonic (20:4 omega 6) and docosahexaenoic (22:6 omega 3) were the fatty acids implicated. In cholesteryl esters palmitoleic (16:1 omega 7) and oleic (18:1 omega 9) acids decreased from birth to 1 month and linoleic acid increased and arachidonic acid dropped, especially in MF fed infants. In triglycerides, palmitic, palmitoleic and stearic acid (18:0) decreased during the first month of life; oleic acid remained constant and linoleic acid increased in all infants, but arachidonic acid decreased only in those fed formula. Free fatty acids showed a similar behavior in fatty acids and in plasma triglycerides. Preterm neonates seem to have special requirements of long-chain PUFA and adapted MF should contain these fatty acids in similar amounts to those of HM to allow the maintenance of an adequate tissue structure and physiology.     

Modification of cell evagination and cell differentiation in quail oviduct hyperstimulated by progesterone

Quail oviduct development is controlled by sex steroid hormones. Estrogen (E) induce cell proliferation, formation of tubular glands by epithelial cell evagination and cell differentiation. Progesterone (P) strongly increases the secretory process in E-treated quails, but inhibits cell proliferation, cell evagination and differentiation of ciliated cells. The balance between E and P is critical for harmonious development of the oviduct. After 6 daily injections of two doses of estradiol benzoate (10 or 20 micrograms/d) and high doses of P (4 mg/d), tubular gland formation by epithelial cell evagination was inhibited, while epithelial cell proliferation occurred, as shown by the height of the villi and the increase in DNA. Secretory processes were strongly stimulated. Ovalbumin, a tubular gland cell marker and avidin, a mucous cell marker, were localized by immunofluorescence and immunogold labeling. Ovalbumin was localized only in the rudimentary tubular glands, whereas avidin was dispersed throughout the secretory cells. High doses of progesterone inhibited tubular gland cell proliferation, disturbed the distribution of avidin and inhibited differentiation of ciliated cells. Ovalbumin synthesis occurred only in epithelial cells which were evaginated despite the hyperstimulation. Ovalbumin gene expression appeared highly dependent upon the cell position.     

Mobilization of the gypsy and copia retrotransposons in Drosophila melanogaster induces reversion of the ovo dominant female-sterile mutations: molecular analysis of revertant alleles

The ovo locus is required for the maintenance of the female germ line in Drosophila melanogaster. In the absence of an ovo⁺ gene, males are completely normal but females have no germ-line stem cells. Three dominant mutations at the ovo locus, called ovo^D, were observed to revert towards recessive alleles at high frequency when ovo^D males were crossed to females of the strain y v f mal. We have found that this strain contains an inordinately high number of gypsy transposable elements, and crossing it with the ovo^D strains results in the mobilization of both gypsy and copia, with high-frequency insertions into the ovo locus: of 16 revertants examined 12 have gypsy and four have copia inserted at 4E, the ovo cytological site. Using gypsy DNA as a tag we have cloned 32 kb of wild-type DNA sequences surrounding a gypsy insertion and characterized molecular rearrangements in several independent revertants: in 10 of them gypsy appears to be inserted into the same site. The orientation of gypsy is strictly correlated with whether the neighbouring lozenge-like mutation appears in the revertants. A distal limit of the ovo locus was molecularly determined from the breakpoint of a deletion affecting closely flanking regions.     

The integrated conjugative plasmid pSAM2 of Streptomyces ambofaciens is related to temperate bacteriophages.

Streptomyces ambofaciens ATCC23877 and derivatives contain the 11-kb element pSAM2 present in an integrated state or as a free and integrated plasmid. This element, able to integrate site-specifically in the genome of different Streptomyces species, is conjugative and mobilizes chromosomal markers. Besides these plasmid functions, we have shown that the site-specific recombination system of pSAM2 presents strong similarities with that of several temperate phages. The integration event is promoted by a site-specific recombinase of the integrase family. The int gene encoding this integrase is closely linked to the plasmid attachment site (attP). A small open reading frame (ORF) overlaps the int gene and the predicted protein exhibits similarities with Xis proteins involved in phages excision. The integrated copy of pSAM2 in strain ATCC23877 is flanked by att sequences (attL and attR). Another att sequence (attX) is present in this strain and attX and attL are the boundaries of a 42-kb fragment (xSAM1) absent, as well as pSAM2, from S.ambofaciens DSM40697. Sequences partially similar to pSAM2 int gene are found near the chromosomal integration zone in both S.ambofaciens strains. The possible origin of pSAM2, an element carrying plasmid as well as phage features, is discussed.     

Class II MHC molecules and the HIV gp 120 envelope protein interact with functionally distinct regions of the CD4 molecule.

A murine T cell hybridoma with a receptor specific for the class I molecule H-2 Dd was transfected with an expressible cDNA for human CD4. Expression of the human class II MHC molecule HLA-DP on Dd-positive murine fibroblasts resulted in a greatly enhanced response of the CD4-positive T cell hybridoma, measured either by lymphokine production or by rosette formation. Inhibition of these functional assays with anti-CD4 monoclonal antibodies implicated the two amino-terminal domains of CD4 in an interaction with the HLA-DP molecule. This interaction was blocked by incubation with recombinant gp120 envelope protein of HIV. In contrast, recombinant soluble CD4 did not inhibit and was able to prevent the inhibition by gp120. Anti-CD4 antibody blocking experiments clearly indicated that distinct regions of CD4 interact respectively with gp120 and with class II MHC molecules.