Distribution of melatonin MT1 receptor immunoreactivity in human retina.

Melatonin is synthesized in the pineal gland and retina during the night. Retinal melatonin is believed to be involved in local cellular modulation and in regulation of light-induced entrainment of circadian rhythms. The present study provides the first immunohistochemical evidence for the localization of melatonin 1a-receptor (MT1) in human retina of aged subjects. Ganglion, amacrine, and photoreceptor cells expressed MT1. In addition, MT1 immunoreactivity was localized to cell processes in the inner plexiform layer and to central vessels of the retina, as well as to retinal vessels but not to ciliary or choroidal vessels. These results support a variety of cellular and vascular effects of melatonin in the human retina. Preliminary evidence from patients with Alzheimer's disease (AD) revealed increased MT1 immunoreactivity in ganglion and amacrine cells, as well as in vessels. In AD cases photoreceptor cells were degenerated and showed low MT1 expression.     

The ΔF508 mutation in cystic fibrosis patients of Southern Italy

Summary Fifty one independent cystic fibrosis (CF) families originating from a restricted area of Southern Italy (Campania) have been analyzed for KM19 and XV2c haplotypes and the ΔF508 mutation: 54% of the total CF chromosomes show the ΔF508 mutation. No significative correlations were obtained when clinical score, radiological score,Pseudomonas colonization, or clinical symptoms at presentation were matched with the presence or absence of the ΔF508 mutation.     

Clostridium quercicolum sp.n., isolated from discolored tissues in living oak trees

Characteristics of an obligate anaerobe isolated from discolored tissues in living oaks were determined. The bacterium was found to be a motile, sporeforming, gram-negative rod which was catalase- and oxidase-negative. The isolate was weakly fermentative and non-proteolytic. Differences in biochemical activities and DNA base composition between the tree isolate and those of recognized species of Clostridia were considered significant enough to propose the new species,Clostridium quercicolum.     

Trisomy-8 mosaicism: Report of a case

Summary An 8-year-old male with mental retardation, speech difficulties, and minor congenital anomalies is presented. The clinical findings suggest the trisomy-8 syndrome. The karyotype indicates trisomy-8 mosaicism with trisomic as well as normal cell lines in blood lymphocytes.     

Role of lactoferrin and its receptors on biliary epithelium

Human lactoferrin is an iron-binding glycoprotein present at high concentrations in breast milk and colostrum. It is produced by many exocrine glands and widely distributed in a variety of body fluids. This protein has antimicrobial, immunomodulatory, antioxidant, and anticancer properties. Two important hLf receptors have been identified: LDL receptor related protein (LRP1), a low specificity receptor, and intelectin-1 (ITLN1), a high specificity receptor. No data are present on the role of hLf on the biliary epithelium. Our aims have been to evaluate the expression of Lf and its receptors in human and murine cholangiocytes and its effect on proliferation. Immunohistochemistry and immunofluorescence (IF) were conducted on human healthy and primary biliary cholangitis (PBC) liver samples as well as on liver samples obtained from normal and bile duct ligated (BDL) mice to evaluate the expression of Lf, LRP1 and ITLN1. Cell proliferation in vitro studies were performed on human cholangiocyte cell lines via 3-(4,5-dimetiltiazol-2-il)-2,5-diphenyltetrazolium assay as well as IF to evaluate proliferating cell nuclear antigen (PCNA) expression. Our results show that mouse and human cholangiocytes express Lf, LRP1 and ITLN1, at higher extent in cholangiocytes from BDL and PBC samples. Furthermore, the in vitro addition of bovine Lf (bLf) has a proliferative effect on human cholangiocyte cell line. The results support a proliferative role of hLf on the biliary epithelium; this pro-proliferative effect of hLf and bLf on cholangiocytes could be particularly relevant in human cholangiopathies such as PBC, characterized by cholangiocyte death and ductopenia.     

Qualitative Analysis of the Carbohydrate Composition of Apolipoprotein H

The specific binding of digoxigenin-labeled lectins to carbohydrate moieties is used to characterize the carbohydrate chains bound to apolipoprotein H. Our results show that apolipoprotein H is rich in sialic acid linked (2–6) to galactose or N-acetylgalactosamine. Sialic acid is not (2–3)-linked to galactose. Galactose is (1–4)-linked to N-acetylglucosamine and (1–3)-linked to N-acetylgalactosamine. High-mannose N-glycan chains are barely detectable. After N-glycosidase F treatment the molecular weight is substantially reduced. The main band is 32,500 daltons. Carbohydrate O-linked chains, which are mainly represented by sialic acid, are (2–6)-linked to galactose or N-acetylgalactosamine. Galactose is also organized in O-linked chains and it is (1–4)-linked to N-acetylglucosamine and (1–3)-linked to acetylgalactosamine. Biochemical analysis of carbohydrate structures reveals that no specific carbohydrate complex is bound to a single isoform.     

Hepatic respiratory compensation and haematological changes in the cave cyprinid, Phreatichthys andruzzii

In several ectotherms, including all members of the Osteichthyes studied so far, the spleen is capable of storing and releasing erythrocytes according to the animal's respiratory needs. The tropical cave cyprinid Phreatichthys andruzzii uses its liver rather than the spleen as the site of accumulation in the respiratory compensation process, like the amphibian Rana esculenta. The reversible process of erythrocyte accumulation in the liver is very evident in animals anaesthetized with chlorobutanol; MS-222, an anaesthetic widely used in lower vertebrates alters all the haematological parameters and is not suitable for studies on blood and respiration. The hepatic respiratory compensation mechanism is as efficient as the splenic one: in animals kept at 18 °C for 24 h the mean liver weight percentage was 70% higher than in specimens kept at 28 °C (2.43% of the body weight compared to 1.39%, in groups of six specimens) while mean red blood cell counts fell from 2.49 to 1.60 · 10¹² per l, in agreement with the haematocrit value and haemoglobin concentration; mean corpuscular volume remained constant (at about 177 fl). Accepted: 15 April 1997     

Fluorescent, internally quenched, peptides for exploring the pH-dependent substrate specificity of cathepsin B.

Cathepsin B is a cysteine protease that in tumor tissues is localized in both acidic lysosomes and extracellular spaces. It can catalyze the cleavage of peptide bonds by two mechanisms: endoproteolytic attack with a pH optimum around 7.4, and attack from the C-terminus with a pH optimum at 4.5-5.5. In this work, seven fluorescent, internally quenched, decapeptides have been synthesized using the prototypical cathepsin B selective substrate Z-Phe-Arg-AMC as a lead, and used to identify the structural factors determining the susceptibility of peptides to hydrolysis at acidic and neutral pH values. Each peptide differs from the others in one amino acid (residue 6) and contains a highly fluorescent Nma group linked to the alpha-amino function of the N-terminal Orn residue and a Dnp group linked to the side chain of the Lys(8) residue acting as a quencher. Proteolytic cleavage was monitored by measuring the increase of fluorescence at 440 nm upon excitation at 340 nm, and the cleavage sites were determined by HPLC followed by ESI-MS analysis. Peptides containing Ala or Phe at position 6 are good substrates for the enzyme at both pH 5.0 and 7.4. By contrast, those containing Glu, Asp, Lys or Val are not cleaved at all by cathepsin B at pH 7.4, and are poorly hydrolyzed at pH 5.0. These findings provide new information for the rational design of cathepsin B-activated peptide-containing anticancer drugs.