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Biomedical subjects

L S Queiroz

Publications and source records attributed to L S Queiroz.

8 recordsLinked to original sources
PubMed1990

Isolation and characterization of hemorrhagic, myonecrotic and edema-inducing toxins from Bothrops insularis (jararaca ilhoa) snake venom.

Bothrops insularis snake venom was fractionated by gel filtration on Sephadex G-150 followed by ion-exchange chromatography on SP-Sephadex C-25. Two active fractions were purified to homogeneity: (1) SIII-SpI, approximate mol. wt 32,000 and N-terminal amino acid residue Val. This fraction showed esterase activity on TAME, edema-inducing activity on the rat hind paw and contractile activity on the isolated guinea pig ileum. The latter two activities were antagonized by benadryl plus methysergide; (2) SIII-SpVI, a myonecrotic and edema-inducing phospholipase, approximate mol. wt 29,000, N-terminal amino acid residue pyro-Glu, consisting of two chains of approximately 15,000 mol. wt each linked by disulphide bridge(s). The induction of edema by this fraction was not antagonized by benadryl plus methysergide, indomethacin, BW755C or BN52021, but it was antagonized by dexamethasone. Three highly purified hemorrhagic heterodimeric fractions, SIII-SpIII-3, SIII-SpIII-4 and SIII-SpIII-5, of approximate mol. wts 26,000, 29,000 and 26,000, and having N-terminal residues of Asx, Asx and Gly, respectively, were further isolated by preparative polyacrylamide slab gel electrophoresis. SIII-SpIII-4 and SIII-SpIII-5 increased the recalcification time of citrated rat plasma. None of the five isolated fractions showed any proteolytic (on casein) or kininogenase activity.

Animals↗
PubMed1990

[Antigenic expression in human choroid plexus carcinoma: report of 2 cases].

Primary neoplasms of choroid plexus are rare. Six morphological variants have been described: papillary, cystic, acinar, mucus-secreting, oncocytic, and anaplastic. The anaplastic variant, the so-called choroid plexus carcinoma, is the rarest of all and can metastasize. The differential diagnosis of the anaplastic variant of choroid plexus neoplasms with adenocarcinomas, melanomas and undifferentiated neoplasms can be troublesome chiefly in adults. The now large use of immunocytochemical techniques in tissue section has become a powerful tool in the analysis of cell lineages, tumoral and non-tumoral. Nevertheless, the choroid plexus neoplasms have shown a complex and a somewhat confusing pattern of antigenic expression. In two choroid plexus carcinomas (one localized in the right lateral ventricle from a boy of 1 year and 9 months old, and the other localized in the left lateral ventricle from a girl of 3 years old) the following antigens were searched (using the avidin-biotin-peroxidase complex): glial fibrillary acidic protein (GFAP) with monoclonal and polyclonal antibodies; cytokeratins of 40-50kDa, cytokeratins of 60-70kDA (callus cytokeratin), neuronal specific enolase (NSE) and S-100 protein with monoclonal antibodies. The two neoplasms showed immunoreactivity against NSE, S-100 protein and cytokeratin of 40-50kDA. The neoplasm of the boy exhibited glial differentiation having immunoreactivity against GFAP with monoclonal and polyclonal antibodies.

Antigens, Neoplasm↗
PubMed1988

Fractionation of Bothrops jararacussu snake venom: partial chemical characterization and biological activity of bothropstoxin.

A myotoxin, bothropstoxin (BthTX), showing no detectable phospholipase A2 activity, was purified to homogeneity from the venom of the Brazilian snake Bothrops jararacussu by a combination of gel filtration on Sephadex G-75 and ion-exchange chromatography on SP-Sephadex C-25. Four phospholipases (Sm-SP1 to Sm-SPIV) were also isolated, the latter showing, similarly to BthTX (Sm-SPv) myonecrotic activity. Approximate mol. wts, as determined by SDS-PAGE, and pI of Sm-SPI to Sm-SPIV are: 22,400-4.2; 15,500-4.8; 13,800-6.9; and 13,200-7.7, respectively. BthTX is a single chain protein, approximate mol. wt 13,000, with 16 half-cystine residues, pI = 8.2 and LD50 = 7.5 mg/kg (i.p.) and 4.8 mg/kg (i.v.) for 20 g mice. The ten first N-terminal amino acid residues show a significant homology to other toxins with phospholipase structure. BthTX is specifically myotoxic, contrary to crude B. jararacussu venom which, although also myotoxic, affects intramuscular arteries and veins leading to thrombosis. BthTX and Sm-SPIV also differ from toxins isolated from the venom of other Brazilian snakes which are strongly hemorrhagic.

Amino Acid Sequence↗
PubMed1979

Massive spinal cord necrosis in schistosomiasis.

Spinal cord lesions are rare in schistosomiasis. Schistosomal ova usually elicit a granulomatous myelitis in which necrotic foci are sometimes observed, but necrotic foci are sometimes observed, but extensive cord necrosis is exceptional. A 19-year-old Brazilian woman had transverse myelitis that ended fatally one month and a half thereafter. Autopsy disclosed a total myelonecrosis below T-4, and ova at Schistosoma mansoni were demonstrated in the necrotic cord tissue and leptomeniges. This is, to our knowledge, the most extensive necrosis of the spinal cord reported to date in schistosomiasis.

Adult↗
PubMed1976

[Systemic candidiasis with localization in the brain. Anatomo-clinical study of 5 cases].

Central nervous system involvement in Candida septicaemia is rare and not more than four cases have been published in Brazil. Five new cases of systemic candidiasis with cerebral lesions are reported. All patients (four adults and a child) had serious underlying diseases and were submitted to heavy long-term antibiotic therapy with multiple drugs. Seizures in one case and neck stiffness in another were the only neurologic signs that could be attributed to candidiasis. In no case were the lesions severe enough to be considered an immediate cause of death. In three patients, no macroscopic changes were evident in the brain, but microabscesses and granulomata were observed on microscopical examination; another patient had two gross areas with necrotic and haemorrhagic appearance in the cerebral hemispheres; the child had only two microscopic granulomata. The aetiological agent was demonstrated by Grocott's methenamine silver technique in all cases. Involvement of organs other than the central nervous system could be demonstrated in three autopsies. Discussion is confined mainly to such aspects as the contributory factors in the pathogenesis of systemic candidiasis as well as the marked rise in the incidence of this condition in the past few decades. It is suggested that the frequence of monilial septicaemia in Brazil may be far more serious than apparent from the scarcity of reported cases.

Adult↗
PubMed1975

An ependymoblastoma of the pons.

A case of ependymoblastoma of the pons in a child is reported, the first so far described in this location. The case adds further evidence for the acceptance of ependymoblastomas as a specific variety of primitive human glioma.

Autopsy↗