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R Chiesa

Publications and source records attributed to R Chiesa.

At least 145 records · Page 8Linked to original sources
PubMed1987

The phosphorylation sites of the B2 chain of bovine alpha-crystallin.

The B2 chain of bovine lens alpha-crystallin is phosphorylated in a cAMP-dependent reaction. By analysis of 32P-labelled chymotryptic peptides isolated from alpha-crystallin obtained from lenses labelled in organ culture, two phosphorylated B2 chain fragments were found. Sequence analysis of the fragments gave the following results: Arg-Ala-Pro-Ser-Trp-Ile-Asp-Thr-Gly-Leu and Ser-Leu-Ser-Pro-Phe corresponding to residues 56 to 65 and 43 to 47, respectively. It is established by this work that B1 is a phosphorylated post-translational product of B2. Both the A2 and B2 chains of alpha-crystallin are phosphorylated at a similar site with the sequence Arg-(X)-Pro-Ser. This is an unusual site for cAMP-phosphorylation since the phosphorylated serine is preceded by a proline residue. It may also be of significance that the other B2 chain phosphorylation site even more radically differs from previously reported cAMP-dependent phosphorylation sites.

Amino Acid Sequence↗
PubMed1987

The phosphorylation of the primary gene products of alpha-crystallin.

The alpha-crystallin primary gene product A2 and its post-translational modified counterpart A1 were isolated from calf lens cortex. The amino acid compositions determined from both chains were almost identical and in excellent agreement with that calculated from the reported sequence of A2. Chemical analysis of phosphate revealed 1 mol/mol of A1 and was negative in A2. Phosphoamino acid analysis demonstrated the presence of phosphoserine only in A1. Chymotryptic peptide maps of A2 and A1 resolved approximately 50 peptides and were strikingly similar. An apparent change in the relative mobility of one peptide was the only difference observed between A1 and A2. Phosphate analysis of this peptide obtained from A1 and A2 was positive only in the peptide from A1. Identical amino acid composition and the sequence Arg-Leu-Pro-Ser-Asn-Val-Asp-Gln-Ser-Ala-Leu was found for the peptide isolated from both chains, corresponding to residues 119 to 129 in the reported sequence of A2. These results indicate that the post-translational modification of A2 to A1 is the result of a phosphorylation reaction rather than a spontaneous nonenzymatic deamidation as previously suggested.

Amino Acid Sequence↗
PubMed1987

Critical role of gonadal hormones on the genotoxic activity of the hepatocarcinogen DL-ZAMI 1305.

The DNA damaging capacity of the sex-dependent hepatocarcinogen beta-blocker DL-1-(2-nitro-3-methyl-phenoxy)-3-tert-butylamino-propan-2-ol (DL-ZAMI 1305) was evaluated in different sex hormonal conditions. A single injection of DL-ZAMI 1305 causes DNA damage in the liver of the female but not the male Wistar rat. When the hormonal environment of the female rat is converted to 'male type' by ovariectomy and 1 week of treatment with testosterone, DNA damage by DL-ZAMI 1305 is completely abolished. On the contrary, in male rats orchiectomy coupled to 17 beta-estradiol administration increases the amount of hepatic DNA damage by DL-ZAMI 1305 to values similar to those observed in intact female rats. DL-ZAMI 1305 induces hepatic DNA damage also when administered to female Sprague-Dawley and Fisher 344 female rats. It is uneffective instead on the male rats of these strains. Moreover, in the female Fisher 344 rat phenobarbital pretreatment reduces the DNA damaging capacity of DL-ZAMI 1305. Our data indicate that the genotoxic activity of DL-ZAMI 1305 depends on the sex-hormonal status of the animal and that this is possibly due to a modulation of the microsomal mixed function oxidase system by sex hormones.

Animals↗
PubMed1987

Identification of the specific phosphorylated serine in the bovine alpha crystallin A1 chain.

Previous work (1,2,3) has indicated that the in vivo post-translational modification of the alpha crystallin primary gene product A2 is due to a specific phosphorylation process involving a serine residue located in a chymotryptic fragment with the sequence ARG-LEU-PRO-SER-ASN-VAL-ASP-GLN-SER-ALA-LEU which corresponds to the residues 119 to 129 of the polypeptide chain. To define which of the two serines is phosphorylated, the present experiments were carried out. The 32P-labeled chymotryptic fragment was obtained from alpha crystallin isolated from the outer cortex of calf lenses incubated in the presence of [32P]-orthophosphate. By analyses of the products obtained after Edman degradation, utilizing electrophoresis in cellulose TLC plates and radioautography, it was possible to locate the phosphate in the serine residue at position 122 in the polypeptide chain. No phosphate could be detected in the serine residue at position 127.

Amino Acid Sequence↗
PubMed1985

cAMP-dependent phosphorylation of bovine lens alpha-crystallin.

This communication reports that the A1 and B1 chains of bovine lens alpha-crystallin are phosphorylated. The conclusion is based on the following evidence: (i) When soluble preparations from lens cortex are incubated with [gamma-32P]ATP, a cAMP-dependent labeling of a high molecular weight protein is obtained. (ii) After NaDodSO4/PAGE, the label is found in two bands with Mr 22,000 and 20,000, corresponding to the B and A chains of alpha-crystallin, respectively. (iii) Isoelectric focusing indicates that the radioactivity is almost exclusively in bands with pI values of 5.58 and 6.70, corresponding to the A1 and B1 chains, respectively. (iv) Similar results are obtained in experiments of [32P]orthophosphate incorporation in lens organ culture. (v) Analyses of the digested protein indicate the label is exclusively in phosphoserine. (vi) 31P NMR analyses of native, proteolytically digested, and urea-treated alpha-crystallin gives a chemical shift of 4.6 ppm relative to 85% H3PO4 at pH 7.4, suggesting that the phosphate is covalently bound to a serine in the protein. An abundance of approximately one phosphate per four or five monomer units was found. (vii) Similar results were obtained by chemical analyses of independently prepared alpha-crystallin samples. The results are consistent with the view that the A1 and B1 chains arise as result of the phosphorylation of directly synthesized A2 and B2 polypeptides. It is suggested that this metabolically controlled phosphorylation may be associated with the terminal differentiation of the lens epithelial cell and the intracellular organization of the lens fiber cell.

Animals↗
PubMed1985

Phosphorylated intermediates of two Ca++-ATPases in membrane preparations from lens epithelial cells.

By incubating preparations enriched in membranes from lens epithelial cells with [gamma 32P]-ATP and Ca++ at 0 degrees C for 15 seconds followed by SDS-PAGE analysis, it was possible to demonstrate a Ca++-dependent [32P]-phosphate incorporation in two polypeptides with Mr 105,000 and 140,000. Treatment of phosphorylated preparations with 0.06 N hydroxylamine at pH 5.4 and 25 degrees C removed the label from both polypeptides indicating that the phosphate was attached to the proteins by an anhydride linkage characteristic of the phosphorylated intermediates of the ATPases. Membrane preparations from sarcoplasmic reticulum and red blood cell studied under the same conditions showed a Ca++-dependent [32P]-phosphate incorporation into polypeptides with Mr 105,000 and 138,000, respectively, corresponding to the phosphorylated intermediates of the Ca++-ATPases present in these preparations. The results suggest the presence of two Ca++-ATPases in lens epithelial cells which, in terms of Mr, appear to be similar to those present in the sarcoplasmic reticulum and the red blood cell plasma membrane, respectively.

Animals↗
PubMed1983

Lens calcium activated proteinase: degradation of vimentin.

The lens has been shown to contain a Ca+2 activated proteinase specific for vimentin. The proteinase is present in the soluble fraction of the cortex but not in the epithelium. It is suggested that this proteinase is expressed during terminal differentiation of the epithelial cells and may be responsible for degradation of the intermediate filaments in the fiber cells. The proteinase is inhibited by EGTA but not by several proteinase inhibitors.

Animals↗
PubMed1982

Liver biopsy and percutaneous cholangiography using a posterior approach. 500 needle biopsies and 121 cholangiographies.

A technique of posterior percutaneous liver biopsy and cholangiography was used in 500 liver biopsies and 121 cholangiographic examinations of the biliary tract. It provided a successful liver biopsy in 98.6 percent of cases and was associated with a less than 2 percent complication rate. Successful cholangiography was possible in all patients with dilated ducts and in 87 percent of patients with normal undilated ducts. Percutaneous cholangiography was associated with a 5 percent complication rate. The advantages of this technique are that it can be performed by relatively inexperienced physicians with minimal risk of hemo- or choleperitoneum. It has a low failure rate and can be performed in obese patients or patients with coagulation defects. The route of entry eliminates the risk of injury to the gallbladder or colon. Due to the posterior position, this technique can be used in relatively uncooperative patients.

Biliary Tract Diseases↗
PubMed1980

[The ultrastructural morphogenetic bases of the adult respiratory distress syndrome].

Sequential study of the submicroscopic pathological events characterising the natural history of the adult respiratory distress syndrome has pinpointed three different development stages related to clinical course and prognosis. In the first stage, the decisive biological element is represented by the increase in capillary permeability, whose morphological substrate consists of the distension of intercellular junctions. The result is the formation of interstitial oedema with the characteristics of the exudate. In the second stage, when reversibility is still possible, fluid and proteins pass into the alveolus. Finally, in the third stage, the persisting stimulus of pulmonary capillaries leads on the one hand to the formation of hyaline membranes and, on the other, to a reactive lung response in the form of interstitial fibrinogenesis and hyperplasia of granular pneumocytes.

Animals↗
PubMed1979

The role of cardiovascular hemodynamics and liver histology in evaluating bleeding cirrhotic patients.

Preoperative cardiovascular hemodynamics and percutaneous liver biopsies were used to evaluate the pathophysiologic factors determining the operative prognosis of patients with cirrhotic liver disease and bleeding esophageal varices. These studies confirm the observations of Siegel that the greater the magnitude of the peripheral abnormalities in vascular tone and oxygen consumption the better must be the capability of the ventricular function, if the cirrhotic is to survive emergency or urgent portal decompressive surgery. These studies also show that the cardiovascular hemodynamics are directly correllated with the nature and degree of the abnormalities in the liver biopsy, and that pathologic and physiologic features of this disease which impact on surgical prognosis can be expressed through the easily obtained Survival Index. Bleeding cirrhotic patients with poor quality hemodynamics and poor histologic characteristics should be treated non operatively, since the operative mortality appears greater than that produced by a strategy of medical supportive therapy and delayed surgery if stabilization occurs.

Biopsy, Needle↗
PubMed1977

[Treatment of shock using pharmacological doses of corticosteroids].

Following a review of present-day knowledge and therapeutic approaches to the treatment of shock, three personal cases are presented. Aetiology differed in the three cases and they were treated with methylprednisolone succinate of sodium (Solu Medrol) at a dose of 30 mg/kg. Treatment resolved the state of shock and enabled the three patients to be operated.

Aged↗