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1.
Biochim Biophys Acta Mol Basis Dis ; 1868(9): 166433, 2022 09 01.
Article in English | MEDLINE | ID: mdl-35569737

ABSTRACT

Methylmalonic aciduria cblB type (MMA cblB type, MMAB OMIM #251110), caused by a deficiency in the enzyme ATP:cob(I)alamin adenosyltransferase (ATR, E.C_2. 5.1.17), is a severe metabolic disorder with a poor prognosis despite treatment. We recently described the potential therapeutic use of pharmacological chaperones (PCs) after increasing the residual activity of ATR in patient-derived fibroblasts. The present work reports the successful generation of hepatocyte-like cells (HLCs) differentiated from two healthy and two MMAB induced pluripotent stem cell (iPSC) lines, and the use of this platform for testing the effects of PCs. The MMAB cells produced little ATR, showed reduced residual ATR activity, and had higher concentrations of methylmalonic acid compared to healthy HLCs. Differential proteome analysis revealed the two MMAB HCLs to show reproducible differentiation, but this was not so for the healthy HLCs. Interestingly, PC treatment in combination with vitamin B12 increased the amount of ATR available, and subsequently ATR activity, in both MMAB HLCs. More importantly, the treatment significantly reduced the methylmalonic acid content of both. In summary, the HLC model would appear to be an excellent candidate for the pharmacological testing of the described PCs, for analyzing the effects of new drugs, and investigating the repurposing of older drugs, before testing in animal models.


Subject(s)
Induced Pluripotent Stem Cells , Methylmalonic Acid , Adaptor Proteins, Signal Transducing , Amino Acid Metabolism, Inborn Errors , Animals , Hepatocytes , Humans , Mutation , Proto-Oncogene Proteins c-cbl
2.
Philos Trans A Math Phys Eng Sci ; 368(1933): 5679-93, 2010 Dec 28.
Article in English | MEDLINE | ID: mdl-21078642

ABSTRACT

In this work, we use a mathematical model for dengue transmission with the aim of analysing and comparing two dengue epidemics that occurred in Salvador, Brazil, in 1995-1996 and 2002. Using real data, we obtain the force of infection, Λ, and the basic reproductive number, R(0), for both epidemics. We also obtain the time evolution of the effective reproduction number, R(t), which results in a very suitable measure to compare the patterns of both epidemics. Based on the analysis of the behaviour of R(0) and R(t) in relation to the adult mosquito control parameter of the model, we show that the control applied only to the adult stage of the mosquito population is not sufficient to stop dengue transmission, emphasizing the importance of applying the control to the aquatic phase of the mosquito.


Subject(s)
Dengue/epidemiology , Disease Outbreaks , Algorithms , Animals , Brazil , Cities , Culicidae , Dengue/diagnosis , Disease-Free Survival , Humans , Models, Statistical , Models, Theoretical , Temperature
3.
Zoonoses Public Health ; 56(5): 229-37, 2009 Jun.
Article in English | MEDLINE | ID: mdl-19068073

ABSTRACT

Feces of 70 diarrhoeic and 230 non-diarrhoeic domestic cats from Sao Paulo, Brazil were investigated for enteropathogenic (EPEC), enterohaemorrhagic (EHEC) and enterotoxigenic (ETEC) Escherichia coli types. While ETEC and EHEC strains were not found, 15 EPEC strains were isolated from 14 cats, of which 13 were non-diarrhoeic, and one diarrhoeic. None of 15 EPEC strains carried the bfpA gene or the EPEC adherence factor plasmid, indicating atypical EPEC types. The EPEC strains were heterogeneous with regard to intimin types, such as eae-theta (three strains), eae-kappa (n = 3), eae-alpha1 (n = 2), eae-iota (n = 2), one eae-alpha2, eae-beta1 and eae-eta each, and two were not typeable. The majority of the EPEC isolates adhered to HEp-2 cells in a localized adherence-like pattern and were positive for fluorescence actin staining. The EPEC strains belonged to 12 different serotypes, including O111:H25 and O125:H6, which are known to be pathogens in humans. Multi locus sequence typing revealed a close genetic similarity between the O111:H25 and O125:H6 strains from cats, dogs and humans. Our results show that domestic cats are colonized by EPEC, including serotypes previously described as human pathogens. As these EPEC strains are also isolated from humans, a cycle of mutual infection by EPEC between cats and its households cannot be ruled out, though the transmission dynamics among the reservoirs are not yet understood clearly.


Subject(s)
Cat Diseases/microbiology , Disease Reservoirs/veterinary , Enteropathogenic Escherichia coli/isolation & purification , Adhesins, Bacterial/genetics , Animals , Brazil , Cats , Diarrhea/microbiology , Diarrhea/veterinary , Enteropathogenic Escherichia coli/genetics , Escherichia coli Proteins/genetics , Feces/microbiology , Humans , Phylogeny
4.
Salvador; s.n; 2008. 88 p.
Thesis in Portuguese | LILACS | ID: lil-506895

ABSTRACT

O dengue, atualmente, se constitui em um dos maiores problemas de saúde pública do mundo, sendo o Brasil o país que mais notificou casos nos últimos anos. A possibilidade de haver diferenças na potencialidade de cada área em produzir casos de dengue, pela sua capacidade de desenvolver populações de mosquitos, entretanto, ainda não está esclarecida. Este estudo, que tem como o bjetivo identificar fatores referentes ao individuo, ao imóvel e a área de residência para ocorrência de infecção pelo vírus do dengue em área urbana, acompanhou 1069 indíviduos, residentes em 30 áreas sentinelas, através de inquéritos sorológicos e coleta de dados das caracteristicas do ambiente, de 1998 a 2000. Verificou-se uma soroincidência média de 85% no periodo, sem diferença significativa para as diferentes áreas...


Subject(s)
Academic Dissertation , Aedes , Dengue , Dengue Virus , Environment , Public Health
5.
Brain Behav Immun ; 11(2): 133-9, 1997 Jun.
Article in English | MEDLINE | ID: mdl-9299062

ABSTRACT

BALB/C mice previously conditioned in a paired regimen in which cycophosphamide was given in association with a novel taste in the drinking water (saccharin, SAC) subsequently received LPS (1mg/mouse) by oral gavage. Subgroups of mice were reexposed to SAC or water respectively, and anti-LPS antibody production measured 6 days later using an ELISA/ELISPOT assay. Our data show that the immune response to this T-independent antigen, administered orally, is amenable to conditioned immunosuppression in this model system.


Subject(s)
Antibody Formation/drug effects , Immunosuppression Therapy , Lipopolysaccharides/antagonists & inhibitors , Administration, Oral , Animals , Conditioning, Psychological , Lipopolysaccharides/pharmacology , Male , Mice , Mice, Inbred BALB C , Spleen/cytology , Spleen/immunology , Time Factors
6.
Rev. argent. cir ; 71(3/4): 91-8, sept.-oct. 1996. ilus
Article in Spanish | LILACS | ID: lil-189355

ABSTRACT

Se presenta una serie de 4 enfermos con mediastinitis necrotizante descendente (MND) de origen dental operados entre 1988 y 1993. Del análisis retrospectivo de su etiología, métodos diagnósticos, tratamiento y evolución surge la importancia del diagnóstico temprano y del tratamiento oportuno y completo, destacando la importancia del abordaje por toracotomía para el tratamiento de la supuración mediastinal, pleural y frecuentemente pericárdica. La morbilidad fue alta por múltiples complicaciones: diabrosis de los vasos del cuello, obstrucción de la vía áerea, broncoaspiración, colecciones pleurales y neumotórax postoperatorios, perforación de úlcera gástrica. La muerte de los primeros 3 de estos 4 enfermos destaca la gravedad de la afección.


Subject(s)
Humans , Male , Adult , Middle Aged , Mediastinitis/surgery , Necrosis/diagnosis , Cellulitis/complications , Cellulitis/therapy , Drainage/standards , Mediastinitis/drug therapy , Mediastinitis/etiology , Mouth Floor/pathology , Necrosis/etiology , Necrosis/surgery
7.
Rev. argent. cir ; 71(3/4): 91-8, sept.-oct. 1996. ilus
Article in Spanish | BINACIS | ID: bin-21263

ABSTRACT

Se presenta una serie de 4 enfermos con mediastinitis necrotizante descendente (MND) de origen dental operados entre 1988 y 1993. Del análisis retrospectivo de su etiología, métodos diagnósticos, tratamiento y evolución surge la importancia del diagnóstico temprano y del tratamiento oportuno y completo, destacando la importancia del abordaje por toracotomía para el tratamiento de la supuración mediastinal, pleural y frecuentemente pericárdica. La morbilidad fue alta por múltiples complicaciones: diabrosis de los vasos del cuello, obstrucción de la vía áerea, broncoaspiración, colecciones pleurales y neumotórax postoperatorios, perforación de úlcera gástrica. La muerte de los primeros 3 de estos 4 enfermos destaca la gravedad de la afección. (AU)


Subject(s)
Humans , Male , Adult , Middle Aged , Aged , Mediastinitis/surgery , Necrosis/diagnosis , Mediastinitis/etiology , Mediastinitis/drug therapy , Mouth Floor/pathology , Necrosis/surgery , Necrosis/etiology , Cellulite/complications , Cellulite/therapy , Drainage/standards
8.
Brain Behav Immun ; 10(1): 44-54, 1996 Mar.
Article in English | MEDLINE | ID: mdl-8735568

ABSTRACT

Mice were given oral immunization after pretreatment with a regimen (cyclophosphamide and a novel taste in the drinking water, chocolate milk (CHM), which leads to suppression of the antibody response to intravenously administered antigens given concurrently with CHM. Following this treatment mice were reexposed to CHM and IgM and IgA antibody forming cells (AFC) were measured in spleen and Peyer's patch cells. Conditioned immunosuppression of AFC production was most marked (> fivefold) for IgA-AFC in Peyer's patch, with effects of lesser magnitude for IgM-AFC in Peyer's patch (twofold) and both IgM- and IgA-AFC in spleen. Analysis of cytokine production from stimulated Peyer's patch and splenic T cells in vitro showed significant decreased production of both IL-2 and IL-4, with the latter being the predominant cytokine produced in Peyer's patch cells of control animals.


Subject(s)
Conditioning, Classical/physiology , Immunosuppression Therapy , Administration, Oral , Animals , B-Lymphocytes/immunology , Cells, Cultured , Erythrocytes/immunology , Immunization , Immunoglobulins/biosynthesis , Mice , Mice, Inbred BALB C , Peyer's Patches/cytology , Peyer's Patches/immunology , Sheep/immunology , Spleen/cytology , Spleen/immunology , T-Lymphocytes, Helper-Inducer/immunology
9.
FEBS Lett ; 336(2): 275-8, 1993 Dec 27.
Article in English | MEDLINE | ID: mdl-8262245

ABSTRACT

The beta-amyloid peptide (A beta) is a 4 kDa proteolytic fragment derived from the beta-amyloid precursor protein (beta APP) which is deposited as amyloid fibrils in the brains of patients with Alzheimer's disease. beta APP processing was investigated in C6 glioma cells using several affinity-purified anti-peptide antibodies raised against different domains of the protein. Both direct immunoblot analysis of C6 glioma conditioned medium and metabolic labeling of cells followed by immunoprecipitation of extracellular medium with specific antibodies revealed that these glial cells normally produce and release a soluble 4 kDa peptide which co-migrates with synthetic A beta (1-40) and is specifically recognized by antibodies raised against N- or C-terminal domains of the beta-amyloid peptide. Our results further suggest that glial cells may prove a major source of beta-amyloid production in the nervous tissue.


Subject(s)
Amyloid beta-Protein Precursor/biosynthesis , Neuroglia/metabolism , Animals , Blotting, Western , Electrophoresis, Polyacrylamide Gel , Glioma , Humans , Peptide Fragments/biosynthesis , Protein Processing, Post-Translational , Rats , Tumor Cells, Cultured
10.
Brain Behav Immun ; 7(3): 224-30, 1993 Sep.
Article in English | MEDLINE | ID: mdl-8219411

ABSTRACT

There is considerable evidence of a relationship between the central nervous system and the immune system, and that several drugs with primary action at the central nervous system can affect different immune responses. In an attempt to obtain a better understanding of the interaction between ethanol's effects and immune functions, we used two mouse lines selected according to their high (HGP) or low (LGP) antibody production. These animals were injected with ethanol (20% w/v, 3.6 g/kg, ip); the latency for the loss of the righting reflex (LORR) and the time for the recovery of the righting reflex (RORR) were measured. Body temperature of both lines was also recorded before the injections and at RORR. Blood samples were taken at RORR to determine blood ethanol concentration. The results showed that the HGP mice presented shorter latency for sleep, longer sleeping time, and lower blood ethanol levels than the LGP mice. These data suggest that the HGP line is more sensitive to the effects of ethanol, and provide an additional approach for studying interactions between the immune and the central nervous systems.


Subject(s)
Antibody Formation/genetics , Body Temperature/drug effects , Ethanol/pharmacology , Mice, Inbred Strains/physiology , Neuroimmunomodulation/drug effects , Receptors, GABA/physiology , Animals , Antibody Formation/physiology , Drug Resistance/genetics , Ethanol/blood , Female , Hypothermia/chemically induced , Male , Mice , Mice, Inbred Strains/immunology , Mice, Inbred Strains/metabolism , Reaction Time/drug effects , Receptors, GABA/genetics , Reflex, Abnormal/drug effects , Selection, Genetic , Sex Factors , Sleep/drug effects
11.
Neuropathol Appl Neurobiol ; 19(3): 261-8, 1993 Jun.
Article in English | MEDLINE | ID: mdl-8355812

ABSTRACT

In this study, we have compared the cellular pathology associated with beta-amyloid (beta A) deposits which characterize Alzheimer's disease (AD) in demented patients with pathologically confirmed AD, with that in non-demented aged individuals. Brain sections from two severely demented AD cases, six non-demented individuals with beta A deposits, and six age-matched controls devoid of beta A deposits were double-immunostained with antibodies against beta A, and antibody markers for neurofibrillary tangles (NFT), astrocytes and microglial cells. We found that the severely demented patients displayed numerous plaques of variable morphology, most of which were associated with NFT, hypertrophied astrocytes and reactive microglial cells. In contrast, non-demented patients showed fewer plaques, few or not NFT and less astroglial and microglial reaction. The number of plaques with associated abnormal cellular elements were much lower in non-demented than in demented cases. Furthermore, classical plaques were more likely to be associated with abnormal cellular elements than diffuse plaques, which were most often devoid of any associated cellular change. These findings suggest that: (i) beta A plaques in non-demented individuals may represent an early stage of AD; (ii) beta A deposition is the first recognizable pathological abnormality of AD; and (iii) NFT, and astro- and microglial proliferation are later features, possibly secondary to the known dystrophic effects of the beta A peptide and other fragments of its precursor protein.


Subject(s)
Alzheimer Disease/pathology , Amyloid beta-Peptides/metabolism , Aged , Aged, 80 and over , Alzheimer Disease/metabolism , Amyloid beta-Peptides/immunology , Astrocytes/metabolism , Astrocytes/ultrastructure , Brain/pathology , Female , Humans , Immunohistochemistry , Male , Middle Aged , Neurofibrillary Tangles/pathology , Neuroglia/metabolism , Neuroglia/ultrastructure
12.
Rev. argent. cir ; 63(1/2): 47-51, jul.-ago. 1992.
Article in Spanish | LILACS | ID: lil-125165

ABSTRACT

El desarrollo de aparatos de endosutura permite realizar biopsias pulmonares toracoscópicas con instrumento abierto o asistidas por video. Las técnicas descriptas aquí logran obtener piezas de un tamaño más apto para el diagnóstico de las enfermedades intersticiales que a las pequeñas biopsias transbronquiales, en condiciones seguras aún en pacientes con suficiencia respiratoria limitada


Subject(s)
Humans , Male , Female , Adult , Middle Aged , Biopsy , Lung/pathology , Suture Techniques/instrumentation , Thoracoscopy , Biopsy/instrumentation , Pulmonary Emphysema/diagnosis , Pulmonary Fibrosis/diagnosis , Suture Techniques , Television/instrumentation , Thoracoscopy/adverse effects , Thoracoscopy/instrumentation , Thoracotomy , Tuberculosis, Pulmonary/complications , Tuberculosis, Pulmonary/diagnosis
13.
Rev. argent. cir ; 63(1/2): 47-51, jul.-ago. 1992.
Article in Spanish | BINACIS | ID: bin-25419

ABSTRACT

El desarrollo de aparatos de endosutura permite realizar biopsias pulmonares toracoscópicas con instrumento abierto o asistidas por video. Las técnicas descriptas aquí logran obtener piezas de un tamaño más apto para el diagnóstico de las enfermedades intersticiales que a las pequeñas biopsias transbronquiales, en condiciones seguras aún en pacientes con suficiencia respiratoria limitada


Subject(s)
Humans , Male , Female , Adult , Middle Aged , Lung/pathology , Thoracoscopy/methods , Biopsy/methods , Suture Techniques/instrumentation , Thoracoscopy/adverse effects , Thoracoscopy/instrumentation , Biopsy/instrumentation , Thoracotomy/methods , Pulmonary Fibrosis/diagnosis , Pulmonary Emphysema/diagnosis , Television/instrumentation , Suture Techniques , Tuberculosis, Pulmonary/complications , Tuberculosis, Pulmonary/diagnosis
14.
Alcohol Clin Exp Res ; 16(1): 38-40, 1992 Feb.
Article in English | MEDLINE | ID: mdl-1558300

ABSTRACT

A number of studies have indicated that prostaglandin synthetase inhibitors (PGSI) can antagonize several effects of ethanol. This study examines the influence of intraperitoneal pretreatment with the PGSI indomethacin (5.0 or 10.0 mg/kg), aspirin (15.0 or 30.0 mg/kg) and acetaminophen (15.0 or 30.0 mg/kg) on the diuretic effect produced by orally administered ethanol (4.0 g/kg) in female rats. Pretreatments with indomethacin and aspirin led to an antagonism of ethanol's diuretic effect. Nevertheless, acetaminophen failed to antagonize this effect. These results are in agreement with data from the literature on PGSI versus ethanol and suggest possible involvement of prostaglandins in the diuretic effect of ethanol.


Subject(s)
Acetaminophen/pharmacology , Alcohol Drinking/physiopathology , Aspirin/pharmacology , Diuresis/drug effects , Indomethacin/pharmacology , Prostaglandins/physiology , Animals , Diuresis/physiology , Dose-Response Relationship, Drug , Female , Rats , Rats, Inbred Strains
15.
J Neurochem ; 56(5): 1690-7, 1991 May.
Article in English | MEDLINE | ID: mdl-1849551

ABSTRACT

We have investigated the effect of chemical reagents that modify sulfhydryl groups on the ligand binding properties of the glycine receptor (GlyR). The Hill coefficient (nH) for the displacement of [3H]strychnine binding by glycine was increased from approximately 0.8 to values significantly above 1 (approximately 1.2-1.4) in membranes pretreated with the disulfide-reducing agent dithiothreitol or glutathione. However, the affinity of strychnine or glycine for the GlyR was not affected by these treatments. This indicates that several glycine binding sites interact cooperatively for displacing bound strychnine under such experimental circumstances. A similar increase in the nH for glycine has been observed when the temperature of the binding assay was increased to 37 degrees C. Combination of dithiothreitol pretreatment and increased binding temperature led to nH variations similar to those observed with either of these treatments alone, a finding suggesting that their mechanisms of action are not independent. Conversely, modification of rat spinal cord membranes or of purified and reconstituted GlyR preparations with the sulfhydryl-alkylating agent N-ethylmaleimide or fluorescein-maleimide decreased nH values to approximately 0.5, without affecting glycine or strychnine affinities. This effect may be caused by an increased heterogeneity of GlyR populations. It is interesting that occupancy of the receptor by glycine or beta-alanine (but not by antagonists) specifically protects from the effects of the different sulfhydryl reagents. Moreover, the presence of some of the Eccles' anions, i.e., anions that permeate through the channels associated with GlyRs and gamma-aminobutyric acidA receptors, seems to be required for the action of both dithiothreitol and N-ethylmaleimide.(ABSTRACT TRUNCATED AT 250 WORDS)


Subject(s)
Glycine/metabolism , Receptors, Neurotransmitter/physiology , Sulfhydryl Compounds/metabolism , Allosteric Regulation , Animals , Anions/pharmacology , Binding Sites , Drug Carriers , Liposomes , Male , Rats , Receptors, Glycine , Receptors, Neurotransmitter/administration & dosage , Sulfhydryl Compounds/pharmacology , Temperature
16.
FEBS Lett ; 276(1-2): 54-8, 1990 Dec 10.
Article in English | MEDLINE | ID: mdl-1702396

ABSTRACT

Using 'inside-out' membrane patches obtained from reconstituted giant liposomes containing purified glycine receptor from rat spinal cord, we have detected chloride currents elicited in response to the presence of the agonists glycine or beta-alanine. Regardless of the agonist employed, two different patterns of single channel currents could be detected, which differ in their main conductance, complexity of substates and opening frequency. In agreement with the expectations of glycine receptor heterogeneity suggested recently at the mRNA and cDNA level, our results indicate the existence of functionally different glycine receptors in the adult rat spinal cord.


Subject(s)
Glycine/pharmacology , Ion Channels/physiology , Membrane Proteins/physiology , Receptors, Neurotransmitter/physiology , Alanine/pharmacology , Animals , Cell Membrane/metabolism , Chloride Channels , Glycine/metabolism , Ion Channels/drug effects , Liposomes , Membrane Potentials , Rats , Receptors, Glycine , Receptors, Neurotransmitter/isolation & purification , Receptors, Neurotransmitter/metabolism , Spinal Cord/metabolism
17.
Biochemistry ; 29(30): 7033-40, 1990 Jul 31.
Article in English | MEDLINE | ID: mdl-2171639

ABSTRACT

Amino acid residues that participate in antagonist binding to the strychnine-sensitive glycine receptor (GlyR) have been identified by selectively modifying functional groups with chemical reagents. Moreover, a region directly involved with strychnine binding has been localized in the 48-kDa subunit of this receptor by covalent labeling and proteolytic mapping. Modification of tyrosyl or arginyl residues promotes a marked decrease of specific [3H]strychnine binding either to rat spinal cord plasma membranes or to the purified GlyR incorporated into phospholipid vesicles. Occupancy of the receptor by strychnine, but not by glycine, completely protects from the inhibition caused by chemical reagents. Furthermore, these tyrosine- or arginine-specific reagents decrease the number of binding sites (Bmax) for [3H]strychnine binding without affecting the affinity for the ligand (Kd). These observations strongly suggest that such residues are present at, or very close to, the antagonist binding site. In order to localize the strychnine binding domain within the GlyR, purified and reconstituted receptor preparations were photoaffinity labeled with [3H]strychnine. The radiolabeled 48-kDa subunit was then digested with specific chemical proteolytic reagents, and the peptides containing the covalently bound radioligand were identified by fluorography after gel electrophoresis. N-Chlorosuccinimide treatment of [3H]strychnine-labeled 48K polypeptide yielded a single labeled peptide of Mr approximately 7300, and cyanogen bromide gave a labeled peptide of Mr 6200.(ABSTRACT TRUNCATED AT 250 WORDS)


Subject(s)
Glycine/metabolism , Receptors, Neurotransmitter/metabolism , Strychnine/metabolism , Amino Acid Sequence , Animals , Binding Sites , Diazonium Compounds/pharmacology , In Vitro Techniques , Kinetics , Male , Molecular Sequence Data , Molecular Weight , Phenylglyoxal/pharmacology , Protein Conformation , Rats , Rats, Inbred Strains , Receptors, Glycine , Receptors, Neurotransmitter/chemistry , Receptors, Neurotransmitter/drug effects , Spinal Cord/metabolism , Sulfanilic Acids/pharmacology
18.
J Ethnopharmacol ; 26(3): 277-86, 1989 Oct.
Article in English | MEDLINE | ID: mdl-2615408

ABSTRACT

Antidiabetic activity of crude extract of leaves of Talauma ovata St. Hil. (Magnoliaceae) was analysed as part of a general pharmacological screening of this plant. Chemical analysis demonstrated the presence of phytosteroids, saponins, alkaloids and tannins in the crude extract. Pharmacological studies failed to demonstrate hypoglycemic effect of this plant in normoglycemic, hyperglycemic or alloxan-diabetic rats. The low LD50 obtained for this plant strongly suggests that its consumption by the population may be hazardous.


Subject(s)
Plant Extracts/pharmacology , Plants, Medicinal , Animals , Female , Guinea Pigs , Hypoglycemic Agents , In Vitro Techniques , Lethal Dose 50 , Male , Mice , Parasympathomimetics , Plant Extracts/analysis , Plant Extracts/toxicity , Rats , Rats, Inbred Strains
19.
Biochemistry ; 28(15): 6405-9, 1989 Jul 25.
Article in English | MEDLINE | ID: mdl-2551372

ABSTRACT

The functional reconstitution of the chloride channel coupled glycine receptor is described. Glycine receptors were purified from the cholate extract of rat spinal cord membranes by affinity chromatography and incorporated into phospholipid vesicles by the addition of phosphatidylcholine and removal of detergent by gel filtration. The reconstituted vesicles showed the same polypeptide composition as the purified receptor (proteins of Mr 48,000 and 58,000). The pharmacological characteristics of the glycine receptor were also preserved in the proteoliposomes, as demonstrated by the displacement of [3H]strychnine binding by several glycinergic ligands and by photoaffinity labeling experiments. In order to observe functional responses (i.e., specific agonist-induced anion translocation), we have developed an assay based on the fluorescence quenching of an anion-sensitive entrapped probe, SPQ [6-methoxy-N-(3-sulfopropyl)quinolinium]. Reconstituted vesicles were loaded with the fluorescent probe during a freeze-thaw-sonication cycle in the presence of added liposomes containing cholesterol. In such a reconstituted system, glycine receptor agonists are able to increase the rate of anion influx into the vesicles. The action of agonists is blocked by the simultaneous presence of strychnine or other glycine antagonists. Our results show that the purified 48,000- and 58,000-dalton polypeptides reconstituted into phospholipid vesicles can bind ligands and promote specific ion translocation in a way similar to the glycine receptor in its native environment.


Subject(s)
Glycine/metabolism , Receptors, Neurotransmitter/metabolism , Spinal Cord/metabolism , 1,2-Dipalmitoylphosphatidylcholine/metabolism , Animals , Cell Membrane/metabolism , Chromatography, Affinity , Chromatography, Gel , Iodides/metabolism , Kinetics , Liposomes , Molecular Weight , Phosphatidylcholines , Rats , Receptors, Glycine , Receptors, Neurotransmitter/isolation & purification , Strychnine/metabolism
20.
Int Surg ; 71(2): 122-4, 1986.
Article in English | MEDLINE | ID: mdl-3733357

ABSTRACT

A retrospective study of 44 surgical procedures performed in 39 patients with late occlusions of radiocephalic fistulas for hemodialysis is reported. In 6 cases (13.6%) no apparent anatomical cause was found, and a simple thrombectomy was performed as a corrective procedure. Some sort of arterial and/or venous stenosis was present in the other 38 cases. In 11 cases with evidence of mild localized vascular stenosis we performed a thrombectomy and then an endoluminal angioplasty with a balloon catheter and Bakes dilators. In 26 cases, with more severe degrees of stenosis, we made a proximal new fistula in the distal portion of the forearm, bypassing the vascular stenosis, either end-to-end radiocephalic or with interposition of a short segment of PTFE graft. The best results were achieved with the creation of a proximal new fistula, which resulted in almost 50% cumulative patency rates at 2 years, with no immediate failures. We think that an attempt at angioaccess salvage should be made in every case of late thrombosis of radiocephalic fistulas.


Subject(s)
Postoperative Complications , Renal Dialysis , Thrombosis/surgery , Humans , Retrospective Studies , Thrombosis/etiology
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