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A F Almeida

Publications and source records attributed to A F Almeida.

51 records · Page 3Linked to original sources
PubMed1984

Photoaffinity labelling of the nucleoside transporter of cultured mouse lymphoma cells.

Nitrobenzylthioniosine (NBMPR), a potent and specific inhibitor of nucleoside transport, is bound reversibly by high affinity sites on nucleoside transporter proteins of erythrocyte membranes and, upon photoactivation, NBMPR molecules become covalently bonded to the sites. This study showed that [3H]NBMPR molecules reversibly bound to intact S49 and L5178Y mouse lymphoma cells became covalently bound upon exposure to UV light. Electrophoretic analysis of plasma membrane fractions from the labelled cells showed that 3H was present in polypeptides which migrated as a major band with an apparent Mr of 45000-65000.

Affinity Labels↗
PubMed1984

Separation of nitrobenzylthioinosine from high affinity binding sites on human erythrocytes by gel chromatography.

The potent inhibitor of nucleoside transport, 6-[(4-nitrobenzyl) mercapto]-9-beta-D-ribofuranosylpurine (NBMPR), binds reversibly, but with high affinity (KD 0.3-1.4 nM) to plasma membrane sites on human erythrocytes, and occupancy of those sites by NBMPR correlates with inhibition of transport. An earlier study from this laboratory showed that, upon photoactivation of site-bound [3H]NBMPR on erythrocyte membranes by exposure to UV light, isotopic ligand molecules became covalently linked to membrane polypeptides, which migrated as a discrete band on gel electrophoretograms, thereby identifying nucleoside transport polypeptides. The present study showed that erythrocytes on which the high affinity sites were occupied by reversibly bound [3H]NBMPR were freed of the latter by slow passage at 37 degrees C through 9 X 300 mm columns of Sephadex G-200 gel. Photoactivation of site-bound [3H]NBMPR on the intact cells caused apparent covalent attachment of the ligand because cells so treated retained the isotopic label during passage through the gel columns. Apparent covalent binding to erythrocytes also resulted from photoactivation of site-bound [3H]nitrobenzylmercaptopurine arabinoside.

Chromatography, Gel↗
PubMed1977

Variation in sensitivity of the cardiac glycoside receptor characteristics of (Na+ + K+)-ATPase to lipolysis and temperature.

1. The rate of binding of [3H]ouabain to untreated membrane preparations of [Na+ +K+]-ATPase is a timperature--dependent process displaying a thermal transition close to 25degreesC. The apparent energies of activation which can be calculated above and below this transition are similar to, but not identical with, those previously reported for activation of the enzyme by cations. 2. Treatment of the enzyme preparation with detergents or lipolysis with phospholipase A eliminates the thermal transition resulting in linear Arrhenius plots. 3. The number of sites available for [3H]ouabain binding is not temperature dependent as the amount of [3H]ouabain bound at equillbrium is not changed between 10 and 37 degrees C. 4. Treatment of the enzyme with phospholipase A results in time-dependent changes in the number of binding sites for [3H]ouabain at equilibrium. 5. Treatment of the membrane enzyme preparations with detergents reveals additional [3H]ouabain binding sites which are extremely sensitive to lipolysis with phospholipase A. 6. There are a number of [3H]ouabain binding sites which remain resistant to lipolysis by phospholipase A in either untreated or detergent-treated membrane preparations. 7. It is suggested that [3H]ouabain binding sites exist in the membrane in at least two different environments, one of which is resistant the other sensitive to attack by phopholipase A.

Adenosine Triphosphatases↗
PubMedDate not supplied

Acute renal failure in a renal transplant donor due to primary antiphospholipid syndrome.

Primary antiphospholipid antibody (APA) syndrome, a common prothrombotic disorder, has been known in dialysis patients and renal transplant recipients. We report a case of primary APA syndrome presenting as a posttransplant complication in a renal transplant donor. A renal donor presented with acute, painless anuria due to renal artery thrombosis 6 years following renal transplant surgery, subsequent thrombosis of jugular catheter and arteriovenous fistula occurred, despite anticoagulation treatment, due to primary APA syndrome. This incident represents the most catastrophic complication reported in a renal donor due to primary APA syndrome. The validity of a prothrombotic assay in an organ donor workup to detect predilection to hypercoagulable disorders and to prevent such complications is open to question. The actual significance of APA in the blood is unclear; hence, the presence of APA in a potential renal donor would pose an ethical and practical dilemma.

Acute Kidney Injury↗
PubMedDate not supplied

A study of anti-neutrophil cytoplasm antibodies in systemic vasculitis and other related disorders.

BACKGROUND: Anti-neutrophil cytoplasm antibodies (ANCA) play an important role as specific and sensitive markers for small vessel vasculitis and in some other systemic disorders. Indirect immunofluorescence test, known as the "Gold Standard" for screening of ANCA, can be further substantiated by ELISA for confirmation and for identifying sub-specificities like anti-Myeloperoxidase (anti-MPO), anti-Proteinase 3 (anti-PR3) and anti-Lactoferrin (anti-LF). AIMS: The present study was undertaken to investigate the incidence, specificities and strength of ANCA in suspected vasculitis cases and to correlate their presence with that of these auto-antibodies and with the disease. SUBJECTS AND METHODS: Sera from 130 clinically suspected vasculitis patients were studied. Indirect immunofluorescence microscopy (IIF) was used to identify cytoplasmic (c-ANCA), perinuclear (p-ANCA) and atypical (X-ANCA) patterns using ethanol and formalin fixed polymorphonuclear cells (PMN) and HL-60 cells from a human promyelocytic leukaemic cell line as substrates. ELISA was performed for identifying ANCA sub-specificities to anti-MPO and anti-PR3 and HEp-2 cells were used for detection of anti-nuclear antibodies (ANA). RESULTS: ANCA positivity was noted in 42.3% of these patients, wherein p-ANCA positivity rate was 34.6% and c-ANCA positivity was noted in 5.4% subjects. Three patients showed the unusual X-ANCA positivity. ELISA determined the sub-specificities: Out of 45 p-ANCA positive patients, 38 patients (84.4%) had anti-MPO and out of 7 c-ANCA positive patients, 5 patients (71.4%) had anti-PR3 antibodies. One patient with Class IV Lupus Nephritis, showed both anti-MPO and anti-PR3 antibodies and 17.8% p-ANCA positive patients had anti-Lactoferrin antibodies. CONCLUSIONS: Use of the Immunofluorescence method coupled with identification of ANCA sub-specificities by ELISA, is recommended for detection of ANCA in clinically suspected cases of small vessel and other systemic vasculitis.

Antibodies, Antineutrophil Cytoplasmic↗
PubMedDate not supplied

Dyslipoproteinemia in renal transplantation.

Twenty-seven live related donor renal allograft recipients were evaluated for dyslipoproteinemia. Twenty-two patients received dual immunosuppression with prednisolone and azathioprine. Five patients received cyclosporin as well. Total cholesterol (Tch), triglycerides (TG), HDL cholesterol (HDLch), LDL cholesterol (LDLch) and VLDL cholesterol (VLDLch) levels were estimated. Fifteen (56%) patients showed significant lipoprotein abnormalities. Renal allograft recipients showed significantly lower levels of Tch (p < 0.05) and LDLch (p < 0.05) and higher levels of TG (p < 0.005) and HDLch (p < 0.05). Diet and beta blockers did not influence lipoprotein levels. A significant negative correlation was noted between post-transplant duration and Tch, TG and VLDLch levels. Increased TG levels were associated with increase in weight and higher daily prednisolone dosage at the time of evaluation. The study confirms the existence of dyslipoproteinemia in renal allograft recipients.

Adolescent↗