Anne Résibois

Localization of transforming growth factor β1 and its latent binding protein in human chronic pancreatitis

BACKGROUND/AIMS Transforming growth factor beta 1 (TGF-beta 1) is thought to be the mediator of fibrosis in liver, glomerular, and pulmonary fibrosis. This study investigated the expression of TGF-beta 1 precursor (beta 1 latency-associated peptide), latent TGF-beta 1-binding protein (LTBP), and TGF-beta 1 messenger RNA (mRNA) in chronic pancreatitis. METHODS Beta 1 latency-associated peptide and LTBP expression were studied by immunohistochemistry, and TGF-beta 1 mRNA expression was studied by reverse-transcription polymerase chain reaction analysis in normal pancreatic parenchyma and in tissues from patients with chronic pancreatitis of different etiologies. RESULTS In normal specimens, TGF-beta 1 precursor was present in islet cells and in a few ductal and acinar cells but not in periductal connective tissue. No immunoreactivity for LTBP was detected. In chronic pancreatitis, TGF-beta 1 precursor was detected mainly in mononuclear cells located in the fibrotic areas and also in ducts damaged by fibrosis, more frequently in calcifying chronic pancreatitis. LTBP was present predominantly in mononuclear cells and in the extracellular matrix around them. TGF-beta 1 mRNA was either not expressed or was faintly expressed in normal tissue, whereas intense signals were detected in chronic pancreatitis. CONCLUSIONS The findings suggest the involvement of TGF-beta 1 in the development of fibrosis in chronic pancreatitis and the important role of inflammatory cells.

φEC2, a new generalized transducing phage of Erwinia chrysanthemi

A collection of Erwinia strains (chrysanthemi and carotovora) was screened for temperate phages. One of them, phiEC2, turned out to be a generalized transducing phage. The structure of its DNA was found to be 62 kb long, terminally redundant, and circularly permuted. The transducing properties of the phage are also briefly described.

A subset of calretinin-positive neurons are abnormal in Alzheimer's disease

The distribution of the calcium-binding protein calretinin was investigated by immunohistochemistry in the hippocampus, the subicular areas, and the entorhinal cortex in patients with Alzheimers disease and in control subjects. By double immunolabelling, the calretinin immunoreactivity was compared to the immunoreactivity for β/A4 amyloid or for tau proteins. Calretinin-positive neurons were mainly observed in the molecular layer of the gyrus dentatus, the stratum radiatum of the Ammons horn, and in layers II and III of the entorhinal cortex. The general pattern of calretinin immunoreactivity was conserved in Alzheimers disease. Calretinin-positive neurons appeared normal in the hippocampus but had a reduced dendritic tree in the entorhinal cortex. Dystrophic calretinin immunoreactive fibres were often observed in the outer molecular layer of the gyrus dentatus and in the CA4 sector in Alzheimers disease. Most neurons containing neurofibrillary tangles were not calretinin immunoreactive and most senile plaques were not associated with calretinin positive fibres. These results show that entorhinal calretinin-positive neurons are affected in Alzheimers disease in spite of an absence of systematic association with neurofibrillary tangles and senile plaques.

Comparison Between Rat Brain Calbindin- and Calretinin-Immuno-reactivities

Several calcium-binding proteins are present in the central nervous system including the closely related protein calbindin-D 28K (Taylor, 1974; Baimbridge et al., 1982), and calretinin (Rogers, 1987). The existence of calretinin became apparent with the demonstration by immunoblotting that rat cerebral extracts contained two proteins cross-reacting with calbindin antiserum (Pochet et al. 1985). The two proteins differed in size with one being about 2 kDa larger than the other. Subsequently, calretinin was cloned and sequenced (Rogers, 1987) and appeared to be identical to the larger protein recognized by anti-calbindin. Because of the high degree of homology between calbindin and calretinin (Rogers, 1987; Wilson et al., 1988 and Parmentier, 1989), antiserum against either protein may cross-react with the other and therefore the immunohistochemical mapping in brain must be re-assessed. The existence of a single immunoreactive protein band in gels made from some brain extracts does not rule out the possibility that calbindin antiserum used recognized calretinin. Indeed, calretinin-like immunoreactivity is negative in large rat brain areas such as cerebral cortex, most parts of the thalamus and hippocampus (Rogers et al. 1989). A single protein band immunoreactive for calbindin antiserum may thus mean lack of calretinin rather than no cross-immunoreactivity. Cross reactivity between calretinin antiserum and calbindin is easier to check because calbindin-like immunoreactivity is present nearly everywhere in the rat brain.

Calbindin-D28 in Mammalian Brain, Retina, and Endocrine Pancreas: Immunohistochemical Comparison with Calretinin

Calbindin 28K and calretinin are very similar calcium binding proteins which are both present in the central nervous system (CNS). They respectively bind 4 and 5 Ca++ ions. We have compared by immunohistochemistry and in situ hybridization their localisation in the brain and the retina. The two proteins are generally expressed in different neurons with a few neurons containing both calcium binding proteins. Calbindin 28K is also present in the endocrine system. We have examined the cellular distribution of calbindin in the pancreatic endocrine cells of chick, rat and human and found variable distribution among the different endocrine cell types. We also describe the presence of calbindin in RINm5F cells, an insulin-producing tumor cell line derived from a radiation-induced rat insulinoma.

Calbindin‐D28K and the peptidergic neuroendocrine system in rat gut: an immunohistochemical study

Calbindin‐D28K was immunohistochemically localized in myenteric and submucosal plexuses throughout the rat intestine. Calbindin‐D28K immunoreactivity was found in about half of myenteric neurons and in more than 90% of submucosal neurons. Calbindin‐D28K was also observed in nerve processes running inside ganglia, muscle layers and lamina propria. No correlation could be established between the presence of calbindin‐D28K and the distribution of neuropeptides localized in this study (VIP, enkephalin, somatostatin and substance P). In addition, some endocrine‐like cells of the ileum were calbindin‐D28K‐positive. Half of these endocrine cells also contained neurotensin but none of the other neuropeptides investigated.

Epithelial and neuronal calbindin in avian intestine An immunohistochemical study

SummaryIt is well known that calbindin immunoreactivity is highly concentrated in the duodenal absorptive cells of young birds. We have shown that in the adult intestine of three avian species, calbindin content is much more variable. In addition to absorptive cells, we have detected throughout the gut of both sexes of the domestic fowl and in the large intestine of the Japanese quail a second type of calbindin-positive epithelial cell which has the shape of a typical endocrine cell. These cells were particularly abundant in the large intestine, in contrast to the usual distribution of endocrine cells along the gut. Calbindin was also detected in the nervous system of the intestine. Calbindinpositive nerve fibres were rare in the duodenum and ileum, numerous in plexuses and nerve processes in both muscular layers and lamina propria of the large intestine in domestic fowl and Japanese quail. In the mallard, nerve fibres were rarely calbindin positive while definitively positive for VIP. Calbindin of the peripheral nervous system of the domestic fowl and Japanese quail comigrates with the duodenal calbindin (27000 dalton) in SDS gel electrophoresis.

GTP-cyclohydrolase-I like immunoreactivity in rat brain

GTPCH-I immunoreactive structures in the rat brain were studied using a polyclonal antibody raised in the chick. General mapping was made using the avidin-biotin-peroxidase technique and compared with the distribution of tyrosine hydroxylase and serotonin immunoreactivities. Double immunofluorescence was performed in order to establish real intracellular colocalization. GTPCH-I immunoreactivity was generally found to be low. Immunostained neurons were present in all the serotonin cell groups. In catecholaminergic neurons, although tyrosine hydroxylase immunoreactivity was always very high, GTPCH-I immunoreactivity was extremely variable, from relatively strong (substantia nigra, ventral tegmental area) to low (locus coeruleus, caudal part of the hypothalamus), extremely low (rostral hypothalamus, ventral brainstem) or almost absent (dorsal brainstem, some hypothalamic nuclei). When feasible, double immunolabeling revealed that all the serotonin cells and most of the tyrosine hydroxylase cells were also expressing GTPCH-I. Our results argue in favor of a regulation of tyrosine hydroxylase activity by the intracellular synthesis of BH4.

Physical characterization of mini-Mu and mini-D108

Several derivatives of phages Mu and D108 have been isolated that carry an internal deletion generated by one of the IS1 components of a Tn9 transposon located in the A, B, or S gene of the prenatal phage. The deletions remove most of the lytic functions of the phage but leave intact either genes A and B or gene A and the left and the right end of the phages. These deleted derivatives, called mini-Mu and mini-D108, were physically characterized by electron microscopy and digestion with restriction enzymes. Mini-Mu and mini-D108, which carry an antibiotic resistance marker, are described and some of their genetic properties are summarized in the paper by Toussaint et al. (1981).

Mini-muduction: A new mode of gene transfer mediated by mini-Mu

SummaryWe compared the transducing properties of Mucts62 and Mucts62/mini-Mu lysates, using Mu immune and non immune Rec+ and recA recipient strains. The Mu/mini-Mu lysates transduced all bacterial markers tested 10 times more efficiently than the Mucts62 lysates in Rec+ recipients. Most of the transductants obtained after infection with the Mu/mini-Mu lysates result from the substitution of the mutated gene of the recipient by the wild type allele from the donor, most probably carried on the gigantic variable end linked to the mini-Mu genome.Moreover the Mu/mini-Mu lysates gave a new type of Rec-independent transduction that we called mini-muduction. Mini-muduction requires the activity of Mu gene A and provides transductants which carry the transduced marker surrounded by two mini-Mu genomes similarly oriented, and inserted at random location in the recipient chromosome. The mini-Mu/transduced DNA/mini-Mu structures are able to transpose spontaneously, for instance into a transmissible plasmid, in the presence of Mu gene A product.