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Biomedical subjects

P Calandra

Publications and source records attributed to P Calandra.

At least 19 recordsLinked to original sources
PubMed1991

An RNA molecule copurifies with RNase P activity from Xenopus laevis oocytes.

Utilizing a procedure for the purification of RNase P from Xenopus laevis germinal vesicle (GV) extracts, according to which the contamination by a large, cytoplasmic, cylindrical structure (1) is avoided, we demonstrate that the X.laevis enzyme, like the HeLa RNase P, is precipitated by anti-Th antibodies and an RNA molecule (XL RNA), 320 nucleotides long, copurifies with the activity. The sequence of XL RNA is 60% homologous to HeLa H1 RNA, therefore the two molecules seem related.

Animals↗
PubMed1989

Site selection by Xenopus laevis RNAase P.

Investigation of the mechanism of cleavage site selection by Xenopus RNAase P reveals that the acceptor stem, a 7 bp helix common to all tRNA precursors, is required for cleavage. We propose that Xenopus RNAase P recognizes conserved features of the mature tRNA and that the cleavage site is selected by measuring the length of the acceptor stem. In support of this, we demonstrate that insertion of 2 bp in the acceptor stem of yeast pre-tRNA(3Leu) relocates the cleavage site 2 bases 3' to the original one. In addition, insertion of 1 bp in the acceptor stem of the end-matured yeast pre-tRNA(Phe) generates an RNAase P cleavage site: the enzyme produces a mature tRNA with the characteristic 7 bp stem and releases one 5' flanking nucleotide. Since it has previously been shown that cleavage sites of the splicing endonuclease are determined by the length of the anticodon stem, RNAase P and the splicing endonuclease apparently use different stems to determine their cutting sites.

Animals↗
PubMed1986

An influenza virus inhibitor that acts late in the replication cycle.

An inhibitor which is active against influenza A virus was found in Neuramide, a complex tissue extract that is used as an anti-herpes zoster virus treatment. Kinetic studies showed that significant inhibition of virus production occurred when the inhibitor was added to infected cultures up to 5 h after virus penetration. Molecular sieving fractionation showed that the antiviral activity was contained in a low-molecular-weight fraction (molecular weight, less than 1,000).

Animals↗
PubMed1978

[Warty dyskeratoma. Analysis and case reports].

Warty dyskeratoma (WD) may be observed in both whites and negros. It is usually small single isolated brown nodule with a prevalent localization of the head of aged males. During the last 4 1/2 years 20 cases were recognized at the Perugia Dermatological Clinic, representing 3.8% of 522 biopsied clinically similar skin tumors. The ratio of WD with keratoacanthoma was 1.3 and with squamous-cell carcinoma 1:5. In 4 cases a lesion clinically similar to squamous-cell carcinoma but with histological picture of WD was localized of the lower prolabium. The excision was the treatment of choice. On the basis of our findings and from a survey of the literature a clinico-pathological picture of the disease is described. Three points are emphasized: 1. WD is frequently localized on the head; when localized on the lower prolabium squamous-cell carcinoma mast be considered in differential diagnosis; 2. no clinical feature is peculiar of the disease; 3. surgical excision is essential for a correct diagnosis when histological examinations are performed on orthogonal and medial sections.

Adult↗
PubMed1975

Statistical association between psoriasis and diabetes: further results.

In a group of 200 psoriatic patients from the area of Umbria, Italy, diabetes mellitus occurred in a statistically highly significant association with psoriasis. Similar observations were made earlier in a series of 600 patients. The above correlation also occurred significantly more frequently in patients under 50 years and in male patients. Previous and present experience also demonstrate that psoriasis is statistically correlated with heredity for diabetes and obesity. The possible biological basis of psoriasis/diabetes association are tentatively outlined.

Adolescent↗
PubMed1975

Research on tryptophan metabolites "via kynurenine" in epidermis of man and mouse.

The pattern of tryptophan metabolites "via kynurenine" was determined in the epidermis of man and mouse using semiquantitative method of one- and two-dimensional thin-layer-chromatography. In the epidermis of healthy man the following metabolites were present: tryptophan, kynurenine, anthranilic acid, 3-hydroxyanthranilic acid, 3-hydroxykynurenine, kynurenic acid, nicotinic acid; the same metabolites, with the exception of kynurenine, were present in the epidermis of healthy mouse. In the epidermis of patients with porphyria cutanea tarda and of those with pellagra, the above pattern was modified and resulted similar to that found in the urine. In the epidermis of patients with pellagroid erythema an alteration of "via kynurenine" metabolites was present. In epithelioma tissues all the above mentioned metabolites were increased while in keratoacanthoma were normal. In burnt epidermis xanthurenic acid was present. In the epidermis of mouse with DDC-porphyria the pattern was characterised by absence of tryptophan, anthranilic and nicotinic acids. These data and those obtained by determination of tryptophan-pyrrolase and kynureninase activities are presented and discussed.

Animals↗
PubMed1975

Tryptophan metabolism in skin diseases.

In a number of skin disturbances conditioned or aggravated by sunlight and/or mainly diffused to the cutaneous connective tissue (present acquired pellagra, lupus erythematosus, porphyria cutanea tarda, actinic reticuloid, Rothmund-Thomson syndrome, lymphocytoma cutis, scleroderma, dermatomyositis, burns, linphomas, parapsoriasis, acrodermatitis enteropathica) excretive changes were found only in the "via kynurenine" metabolites. As a rule kynureniase activity was reduced and tryptophan-pyrrolase activity was increased. In the epidermis tryptophan leads to niacin pathway was found to be present and sometimes autonomous.

Animals↗
PubMed1973

[Pellagra].

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Female↗