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Biomedical subjects

C A Silva

Publications and source records attributed to C A Silva.

At least 19 recordsLinked to original sources
PubMed1992

Determination of the immunoreactive fraction of radiolabeled monoclonal antibodies directed against intracellular antigens.

For investigations involving monoclonal antibodies (mAbs) against cellular antigens cell binding assays are routinely used to determine the immunoreactive fraction after radiolabeling. In general, surface antigens are targets for radioimmunodetection, but recent studies indicate that intracellular determinants may also prove useful for this purpose. Thus, there is a need to adapt the regular cell binding assay for use with antibodies directed against cytoplasmic antigens. Here we describe a fixation method which permits such mAbs to bind to cell surfaces as well as to intracellular determinants. Moreover, the procedure may be used for antigens that are sensitive to the commonly used aldehyde fixatives. The method is illustrated with two human IgM mAbs 16.88 and 28A32, which recognize cytoplasmic antigens. Human colon cancer cells in suspension were fixed with either acetone or glutaraldehyde. Intracellular antigens appeared to be best exposed for antibody binding after fixation with acetone as determined by immunofluorescent staining and flow cytometry. An antibody directed against the cell surface antigen HLA class I showed similar binding with both live cells and acetone-fixed cells. Double-inverse plots of the binding of radiolabeled 16.88 or 28A32 antibody with acetone-fixed cells gave reliable immunoreactive fraction values. Acetone-fixed cells stored at 4 degrees C could be used for immunoreactivity assays for at least 6 months without loss of performance.

Acetone↗
PubMed1990

Fever response induced by intravenous and intracerebroventricular injection of pyrogen in thyroidectomised and protein-calorie malnourished rabbits.

The development of a fever in response to intravenous (IV, 1.5 micrograms/kg body mass) and intracerebroventricular (ICV, 1.5 micrograms/animal) injections of Escherichia coli lipopolysaccharide (LPS) was studied in control, thyroidectomised and protein-calorie malnourished rabbits (New Zealand Whites, n = 55). ICV injection of LPS in control rabbits produced a fever response, the characteristics of which differed from those obtained after IV pyrogen injection. Thyroid deficiency caused an attenuated fever response, irrespective of whether LPS had been administered by IV or ICV injection. Protein-calorie malnourished rabbits showed a smaller fever response after IV or ICV pyrogen injections. Malnourished rabbits, refed over a period of 15 days, showed a typical biphasic fever response, but with lower magnitude than controls. The results of these experiments suggest that ICV injection of LPS is not an appropriate model for the study of fever mechanisms in disease states, and that the attenuated fever response observed in protein-calorie malnourished rabbits may be related, at least in part, to a decreased ability to produce the endogenous pyrogen interleukin-1.

Animals↗
PubMed1989

Cytoproteic CSF findings in 33 MS patients: usefulness for diagnosis.

Although multiple sclerosis (MS) is mainly defined on clinical grounds, CSF parameters still remain important diagnostic and scoring tools. To demonstrate the usefulness of some easy laboratory techniques, a CSF cytomorphological and agarose gel electrophoresis (AGE) evaluation was undertaken in 33 MS patients: 79% presented a lymphoid cell profile and in 73% the gamma globulin fraction was abnormal. In the great majority of cases (97%) either or both cytological and electrophoretical abnormalities were found.

Adolescent↗
PubMed1987

The development of a febrile response to pyrogen in the thyroid-deficient rabbit.

The development of the febrile response to E. coli lipopolysaccharide (1.5 micrograms/kg, i.v.) in thyroid-deficient rabbits has been studied. Twenty-eight New Zealand White rabbits weighing 2.1-2.3 kg were used. Hypothyroidism was induced by treatment with propylthiouracil (100 or 200 mg/kg body wt./15 days). Thyroid-deficient animals showed a reduction in the febrile response to lipopolysaccharide, but the effect was significantly different (p less than 0.01) from the control only for rabbits treated with 200 mg/kg of propylthiouracil. Propranolol (2 mg/kg, i.p.) given 30 min before lipopolysaccharide also reduced (p less than 0.01) the fever response in control rabbits. The results of this experiment are consistent with the hypothesis that the reduction in the febrile response of thyroid-deficient rabbits is due to the reduced number of beta-adrenergic receptors, or to a change in the availability of neurotransmitter in thermogenically active tissues, such as brown fat.

Animals↗
PubMed1987

Consequence of excess iodine supply in a Thoroughbred stud in southern Brazil.

Excessive iodine supply of at least 700 mg inorganic iodine in foals and of more than 350 mg iodine in pregnant and lactating mares cause a high incidence of goitres in the newborn and disorders in the long leg bones of foals. Elevated phosphorus and alkaline phosphatase content in the blood may indicate a severe disturbance in the bone metabolism. Of 39 pregnant mares 17 aborted and some of the mares also showed goitres. After withdrawal of the iodine supply normalization took place. Foals born more than 6 weeks later showed normal conditions. The goitres in the mares and the high blood levels of iodine decreased.

Animals↗
PubMed1986

Clinical and CSF cyto-proteic findings in 23 patients with CSF eosinophilia.

Clinical diagnosis and cerebrospinal fluid (CSF) protein pattern were studied in 23 patients who had eosinophilic granulocytes in the CSF. Clinical data revealed that an inflammatory disorder of the central nervous system (CNS) was evident in 20 cases. A lymphoid reaction and elevated CSF total protein were found in most of the cases, but the most important finding was an increase of CSF gamma-globulin in 12 patients, of whom 10 had oligoclonal patterns. Our results may give support to a relationship between intrathecal eosinophilic reaction and inflammatory diseases of the CNS with subacute or chronic course accompanied by intrathecal synthesis of immunoglobulins.

Cerebrospinal Fluid Proteins↗
PubMed1986

Tuberculous aortitis presenting with an aortoduodenal fistula: a case report.

An elderly man with tuberculous aortitis presented with massive gastrointestinal bleeding resulting from an aortoduodenal fistula. Aortic resection was successful, and he has done well over a 12 year period. The organism was recovered from the aorta and also seen on section of the neighboring lymph nodes. Although tuberculous aortitis is rare, it should be considered in a patient with prior history of tuberculosis who has developed evidence of aortic disease, aneurysm, or massive gastrointestinal bleeding.

Aged↗
PubMed1985

Double infection of the CNS with herpes simplex and mumps viruses. Serological and ultrastructural studies.

Clinical, serological and ultrastructural features are described in a case of acute encephalitis. The ultrastructural study of brain biopsy specimens revealed herpes-and paramyxovirus-like particles in neurons and glial cells that were characterized as herpes simplex and mumps viruses by serological study in serum and CSF. Of the few cases previously reported with double encephalitis, this is the only one in which ultrastructural and serological evidence of combined brain infection has been found.

Antibodies, Viral↗
PubMed1985

Local immunoglobulin synthesis and blood-brain barrier assessment in subacute sclerosing panencephalitis.

The immunoglobulin synthesis within the central nervous system and the blood-brain barrier (BBB) function were evaluated in 6 patients with subacute sclerosing panencephalitis (SSPE) using the IgG index and a graphic method based on serum/CSF albumin, alpha 2-macroglobulin, and IgG quotients. A strong local production of IgG was documented by both methods in all 6 cases of SSPE. Concerning the graphic analysis, the decrease in the serum/CSF alpha 2-macroglobulin ratio disclosed BBB dysfunction in 2 cases of SSPE, suggesting, in the absence of the serum/CSF albumin quotient abnormalities, that a homeostatic mechanism for CSF proteins can cause changes in the CSF protein profile.

Adolescent↗
PubMed1981

Protein patterns of the cerebrospinal fluid of 30 patients with subacute sclerosing panencephalitis (SSPE).

Lumbar cerebrospinal fluid (CSF) from 30 cases of subacute sclerosing panencephalitis (SSPE) was studied for total protein and protein electrophoresis. Total CSF protein values were normal in almost all the cases, but the gamma-globulin was increased and had an oligoclonal morphology in all the cases. Absolute and relative values of some of the other electrophoretic fractions were decreased. Total protein and electrophoretic serum values in 25 cases did not differ significantly from the controls, although the gamma-globulin presented an oligoclonal morphology in 13 cases. CSF immunoglobulins were determined in 10 cases; IGG was increased in ll; IgA was traceable and slightly increased in only four cases; IgM was not found. These findings point to the intrathecal synthesis of IgG and the absence of barrier impairment. The decrease of the absolute values of some of the other CSF proteins suggests that homeostatic mechanisms for protein concentration in the CSF are maintained in SSPE.

Adolescent↗
PubMed1981

Axo-dendritic abnormalities in a case of juvenile neuronal storage disease.

Axonal enlargements (meganeurites) and dendritic degeneration were found in the pyramidal neurons from the frontal cortex of a patient with juvenile neuronal storage disease studied with the aid of ultrastructural and Golgi methods. Meganeurites appeared as enlargements at the axon hillock-initial segment area and were similar to those described in other neuronal diseases; dendritic degeneration was heavy and appeared throughout the cell domain. These neuropile changes can be related to the precocious mental abnormalities observed in this group of diseases which depend on a storage phenomenon due to a lysosomal enzyme deficiency.

Adolescent↗
PubMed1980

Oligoclonal gamma-globulin of cerebrospinal fluid in neurobrucellosis.

The clinical manifestations and laboratory findings of two cases of neurobrucellosis are described. The cerebrospinal fluid (CSF) protein electrophoresis showed increased gamma-globulins and decreased relative values of pre-albumin and albumin, associated to high values of total CSF protein. The evidence of oligoclonal morphology of CSF gamma-globulins suggests that part of them had an intrathecal origin, in addition to an increased crossing of the damaged blood-CSF barrier. Similar oligoclonal appearance of CSF gamma-globulins was observed in two additional cases of neurobrucellosis previously reported.

Brucellosis↗
PubMed1980

Pathological findings in one of two siblings with Sjögren-Larsson Syndrome.

The clinical features of 2 new cases of Sjögren-Larsson syndrome are described. Histopathological examination of the skin in 1 of the cases revealed an ichthyosis vulgaris, which does not agree with the clinical and genetic classification. In the same case, a neuroblastoma was the cause of death, and neuropathological examination showed a symmetrical demyelination of some ascending and descending long tracts in the medulla and spinal cord.

Adult↗
PubMed1980

Peculiar cerebrospinal fluid protein patterns in two cases of infantile hydrocephalus.

Cerebrospinal fluid (CSF) protein abnormalities in 2 hydrocephalic children are described. 1 of the cases presented a degenerative pattern in lumbar CSF protein electrophoresis in spite of high total protein content. This is thought to be due to an excess of tissue proteins as a result of abnormal conditions of circulation and absorption of CSF in hydrocephalus. The other case makes clear the role of inflammation on CSF protein electrophoretic patterns.

Albumins↗
PubMed1979

Neurofibrillary changes in the cerebral cortex of a patient with subacute sclerosing panencephalitis (SSPE).

Biopsy fragments from the frontal cortex of one patient with SSPE were studied with ultrastructural methods. Special attention was given to the presence of neurofibrillary tangles observed in all cortical layers. These tangles were composed either of filaments with a diameter of 10 -- 12 nm or of paired helical filaments 22 -- 24 nm at their widest and periodically reduced to 10 nm about every 80 nm. These tangles were observed in all cortical layers, while those formed by single filaments were only visualized in layer 3. The simultaneous appearance of both types of tangles in the same patient suggests that they may be chemically related, which is in keeping with recent chemical data concerning the nature of the neurofilament protein subunit.

Adolescent↗
PubMed1978

Electrophoretic pattern of cerebrospinal fluid proteins in non-neoplastic infantile hydrocephalus.

Lumbar cerebrospinal fluid (CSF) from 28 non-neoplastic hydrocephalic children was studied for total protein and electrophoretic protein patterns. These were classified as normal, degenerative, transudative and gamma-globulinic according to Laterre. We found higher total CSF protein mean values than in normal cases with the same age and abnormal electrophoretic patterns in 72% of the cases, of which degenerative was the most common (54%). Gamma-globulinic and transudative patterns were found in 11% and 7% of the cases, respectively. Several factors which may explain the increase in the total CSF protein in infantile hydrocephalus are described: low age, ventricular block in the noncommunicating hydrocephalus, and probable passage of tissue proteins to the CSF from the damaged brain. The predominance of degenerative patterns may be explained by the enrichment of the CSF in tissue proteins resulting from the white matter damage provoked by the abnormal conditions of production, flow and absorption of the CSF in hydrocephalus. Ventricular CSF was studied in four cases, and the results obtained are in agreement with the above-mentioned findings.

Albumins↗