Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 21
Filtrar
Mais filtros










Intervalo de ano de publicação
1.
S Afr Med J ; 110(3): 204-209, 2020 Feb 26.
Artigo em Inglês | MEDLINE | ID: mdl-32657697

RESUMO

BACKGROUND: South Africa (SA) has very low and unchanging organ donation rates. A key point in the pathway of organ donation is obtaining informed consent from the family, which is necessary before organ donation can proceed. There is no published SA research on the consent rate and factors that influence this. OBJECTIVES: To describe the number of requests for consent and factors influencing this process in the SA context. METHODS: A prospective descriptive study was performed of all requests to families for organ donation in Western Cape Province, SA, by Groote Schuur Hospital (state sector), Red Cross War Memorial Children's Hospital (state sector) and Netcare (private sector) transplant co-ordinators from 1 May 2017 to 1 May 2018 to describe factors influencing consent rates. RESULTS: The 6 co-ordinators (3 state sector and 3 private sector) recorded data of 83 consecutive families approached in 16 hospitals over the 1-year period. Consent to organ donation was granted for 23 family requests (n=18 (state sector); n=5 (private sector)). The number of families approached was greater in the state sector (n=74) than in the private sector (n=9). The overall consent rate was 27.7% (24.3% (state sector); 55.5% (private sector)). The majority of referrals came from trauma and emergency units (n=55; 66.3%) and very few from intensive care units (n=25; 30.1%). Immediate fluid resuscitation was required in 56 (67.5%) potential donors. The majority of families (n=74; 89.2%) were receptive to the organ donation request, independent of their ultimate decision regarding donation. The main reason given for refusing to consent was that it was against their religion (n=21) or culture (n=18). CONCLUSIONS: This study showed that the number of families approached for consent to organ donation were low in the Western Cape (lower in the private sector), with a low consent rate (lower in the state sector). Donor management by clinical teams needs to be ongoing and active during the consent process. Consent discussions (and public awareness initiatives) need to be sensitive to and deal with religious and cultural reservations about organ donation.


Assuntos
Obtenção de Tecidos e Órgãos/estatística & dados numéricos , Cultura , Família , Humanos , Consentimento Livre e Esclarecido , Estudos Prospectivos , Religião , África do Sul
2.
Artigo em Inglês | MEDLINE | ID: mdl-37063498

RESUMO

Background: Internationally, the declining number of organ donors does not meet the rising demand for life-saving solid organ transplant operations. Critical care professional nurses play an important role in the identification of organ donors. A deeper understanding is needed of the missed opportunities of identification and referral of potential organ donors to organ transplant co-ordinators in the critical care environment. Objectives: To describe the knowledge and views of critical care professional nurses (CCPNs) in South Africa concerning the early identification and referral of organ donors, and to describe the short-term effect of implementing a PowerPoint training intervention on nurses' knowledge in this domain. Methods: A mixed method, experimental, exploratory, descriptive study design was followed. Critical care professional nurses in seven intensive care units at five private hospitals completed a data collection instrument comprising 11 quantitative and three qualitative questions, before and after completing a PowerPoint training intervention. The post test was done directly after the training intervention due to the environment of nursing shift work. Results: A total of 173 (79%) CCPNs participated, from a population of 218. The median (interquartile range) score for all participants increased from 60% (48 - 76) prior to the PowerPoint training intervention, to 96% (88 - 96) after the intervention (p<0.0001). Three main themes emerged from the qualitative questions: stress experienced by the CCPNs during the organ donor process (62%); inadequate collaboration between doctors and nurses (34%); and the need for a policy (9%) to guide the donor referral process. Conclusion: CCPNs' knowledge regarding the early identification and referral of potential organ donors increased significantly following a targeted PowerPoint training intervention. The identified themes suggest that CCPNs require support in order to effectively communicate with the donor's family and medical staff. Contributions of the study: The findings of this study will contribute to the increase in organ donor referrals. Increased education of critical care professional nurses and doctors on effective communication, and the early identification and referral of organ donors, will expectedly help to resolve the critical barriers in the organ donor process.

3.
Artigo em Inglês | AIM (África) | ID: biblio-1272281

RESUMO

Background. Internationally, the declining number of organ donors does not meet the rising demand for life-saving solid organ transplant operations. Critical care professional nurses play an important role in the identification of organ donors. A deeper understanding is needed of the missed opportunities of identification and referral of potential organ donors to organ transplant co-ordinators in the critical care environment. Objectives. To describe the knowledge and views of critical care professional nurses (CCPNs) in South Africa concerning the early identification and referral of organ donors, and to describe the short-term effect of implementing a PowerPoint training intervention on nurses' knowledge in this domain. Methods. A mixed method, experimental, exploratory, descriptive study design was followed. Critical care professional nurses in seven intensive care units at five private hospitals completed a data collection instrument comprising 11 quantitative and three qualitative questions, before and after completing a PowerPoint training intervention. The post test was done directly after the training intervention due to the environment of nursing shift work. Results. A total of 173 (79%) CCPNs participated, from a population of 218. The median (interquartile range) score for all participants increased from 60% (48 - 76) prior to the PowerPoint training intervention, to 96% (88 - 96) after the intervention (p<0.0001). Three main themes emerged from the qualitative questions: stress experienced by the CCPNs during the organ donor process (62%); inadequate collaboration between doctors and nurses (34%); and the need for a policy (9%) to guide the donor referral process. Conclusion. CCPNs' knowledge regarding the early identification and referral of potential organ donors increased significantly following a targeted PowerPoint training intervention. The identified themes suggest that CCPNs require support in order to effectively communicate with the donor's family and medical staff


Assuntos
Barreiras de Comunicação/educação , Médicos , África do Sul , Doadores de Tecidos
4.
Sci Total Environ ; 624: 945-954, 2018 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-29275257

RESUMO

Naturally-occurring pristine estuarine ecosystems are rare in modern environments due to anthropogenic encroachment. There are more than 100 outlets around the South African coast arising from streams flowing from small catchments close to the sea. Eight near natural systems were sampled seasonally over the period of a year to acquire baseline information on water quality and chlorophyll a status across a variety of algal guilds (benthic microalgae, phytoplankton and macroalgal cover). Albeit on a much smaller-scale, these systems represent natural surrogates of larger temporarily open/closed estuaries (TOCEs). Inorganic nutrients (ammonium, total oxidized nitrogen and soluble reactive phosphate), phytoplankton and microphytobenthos chlorophyll a, as well as macroagal percentage cover, were measured using standard methods. Algae showed a seasonal trend, with blooms of both micro- and macro-algae occurring during summer, with a dieback recorded in autumn. During summer, only one system had a phytoplankton peak in chlorophyll a above 20µgL-1, while the microphytobenthos concentrations in three of the systems were above 100mgm-2. Summer blooms of green filamentous macroalgae occurred in all four micro-outlets and in one micro-estuary. Using a linear mixed-effects modelling approach, significant drivers for algal growth related to temperature, nutrient conditions, light availability and water residence time, all of which are known to stimulate primary production. The results show that enrichment from natural sources display similar responses from primary producers to mesotrophic and/or eutrophic water bodies, with the exception that they revert to a natural state rather than continue into a degraded state as is the case in artificially enriched systems. This importantly demonstrates how larger temporarily/open closed estuaries, most of which are anthropogenically degraded, might have functioned under a former more balanced state. Some of these larger systems now respond to nutrient enrichment by exhibiting permanent cultural eutrophication.


Assuntos
Estuários , Eutrofização , Microalgas/crescimento & desenvolvimento , Fitoplâncton/crescimento & desenvolvimento , Compostos de Amônio/análise , Clorofila/análise , Clorofila A , Modelos Lineares , Nitrogênio/análise , Fosfatos/análise , Estações do Ano , África do Sul , Qualidade da Água
5.
Mar Pollut Bull ; 92(1-2): 227-232, 2015 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-25599629

RESUMO

In this study metal accumulating abilities of three emergent macrophytes (Phragmites australis, Typha capensis and Spartina maritima) were investigated in the urbanised Swartkops Estuary. Plants and sediment samples were collected at seven sites along the banks of the main channel and in adjacent canals. Sediments and plant organs were analysed, by means of atomic absorption spectrometry, for four elements (Cd, Cu, Pb, and Zn). Metal concentrations in the sediments of adjacent canals were found to be substantially higher than those at sites along the banks of the estuary. These differences were reflected in the plant organs for Pb and Zn, but not for Cu and Cd. All three species exhibited significantly higher concentrations of metals in their roots. These species are therefore suitable for use as indicators of the presence and level of heavy metal contaminants in estuaries.


Assuntos
Monitoramento Ambiental/métodos , Metais Pesados/análise , Poaceae/química , Poluentes Químicos da Água/análise , Estuários , Sedimentos Geológicos/análise , Sedimentos Geológicos/química , Raízes de Plantas/química , Raízes de Plantas/metabolismo , Poaceae/metabolismo , África do Sul , Espectrofotometria Atômica , Áreas Alagadas
6.
J Med Ethics ; 35(3): 180-2, 2009 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-19251970

RESUMO

The aim of this study was to determine the opinions of private medical practitioners in Bloemfontein, South Africa, regarding euthanasia of terminally ill patients. This descriptive study was performed amongst a simple random sample of 100 of 230 private medical practitioners in Bloemfontein. Information was obtained through anonymous self-administered questionnaires. Written informed consent was obtained. 68 of the doctors selected completed the questionnaire. Only three refused participation because they were opposed to euthanasia. Respondents were mainly male (74.2%), married (91.9%) and Afrikaans-speaking (91.9%). More were specialists (53.2%) than general practitioners (46.8%). A smaller percentage (35.5%) would never consider euthanasia for themselves compared to for their patients (46.8%). The decision should be made by the patient (50%), the patient's doctor with two colleagues (46.8%), close family (45.2%) or a special committee of specialists in ethics and medicine (37.1%). The majority (46.9%) indicated that euthanasia should be performed by an independent doctor trained in euthanasia, followed by the patient's doctor (30.7%). Notification should mainly be given to a special committee (49.9%). Only 9.8% felt that no notification was necessary. There was strong opposition to prescribing of medication to let the patient die. Withdrawal of essential medical treatment to speed up death was the most acceptable method. Although the responding group was fairly homogeneous, responses varied widely, indicating the complexity of opinions.


Assuntos
Atitude do Pessoal de Saúde , Atitude Frente a Morte , Tomada de Decisões/ética , Eutanásia , Médicos/ética , Doente Terminal , Suspensão de Tratamento/ética , Adulto , Idoso , Coleta de Dados , Eutanásia/ética , Eutanásia/psicologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Prática Privada , África do Sul
7.
Artigo em Inglês | AIM (África) | ID: biblio-1272270

RESUMO

Oral hygiene care includes a combination of nursing activities that are often placed very low on the priority care list for a critically ill patient. This may have detrimental implications for the patient. A literature review was done to identify and describe the available evidence related to the beneficial effects of oral hygiene care and the way in which oral hygiene practices should be implemented for a critically ill patient. Various implications of poor oral hygiene care are highlighted; as well as the barriers that have been identified to preventing good oral hygiene care practice. A discussion of the available research evidence to guide oral hygiene care activities includes aspects of timing as well as recommended 'tools'. While some nursing-led research has been published on this topic; there is scope for further investigation into oral hygiene care practices in the critically ill


Assuntos
Cuidados Críticos , Unidades de Terapia Intensiva , Cuidados de Enfermagem , Higiene Bucal
8.
Int J Impot Res ; 15(1): 18-21, 2003 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-12605236

RESUMO

This study investigates whether a hydrophilic coating (Resist), designed to inhibit bacterial adherence, applied to inflatable penile prostheses can prolong the effect of intraoperative antibiotics. The activity of antibiotic-soaked Bioflex (penile prosthetic substrate material) discs with and without Resist was examined by measuring the zone of inhibition following in vivo exposure in four groups of rabbits: 1, 2, 3 and 5 days' duration of disc implantation. Coated and uncoated discs were soaked in an aqueous solution of gentamicin and bacitracin. The implanted antibiotic-soaked discs were extracted, and the zone of inhibition against four microorganisms in vitro demonstrated that the Resist coating was especially effective against Staphylococcus epidermidis, and statistically significant improvements were observed for the coated over the uncoated substrate up to 3 days following implantation. This effect, and the anti-adherence properties of Resist, may prevent adhesion and colonization of some microorganisms to penile implants and reduce chances for infection.


Assuntos
Disfunção Erétil/cirurgia , Prótese de Pênis/microbiologia , Infecção da Ferida Cirúrgica/tratamento farmacológico , Animais , Aderência Bacteriana/efeitos dos fármacos , Masculino , Complicações Pós-Operatórias/tratamento farmacológico , Complicações Pós-Operatórias/prevenção & controle , Coelhos , Infecções Estafilocócicas/tratamento farmacológico , Infecções Estafilocócicas/prevenção & controle , Staphylococcus epidermidis , Infecção da Ferida Cirúrgica/prevenção & controle
10.
J Urol ; 154(4): 1378-81, 1995 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-7658543

RESUMO

PURPOSE: We investigated a possible bacterial etiology for prostatodynia. MATERIALS AND METHODS: We evaluated segmented urine specimens from 22 patients and 16 controls by bacteriological localization studies. Immunological studies were performed on patient and control sera. RESULTS: Nine patients had positive cultures from prostatic secretions. When compared to controls, this novel finding was statistically significant (p < 0.025). Coagulase-negative staphylococci were the most common isolates (68%). No humoral (IgG) immune differences were found between patients and controls. CONCLUSIONS: In a subset of prostatodynia patients bacteria may have an etiological role. Antibiotic treatment demonstrated clinical efficacy.


Assuntos
Infecções Bacterianas , Dor/microbiologia , Prostatite/microbiologia , Adulto , Infecções Bacterianas/tratamento farmacológico , Humanos , Masculino , Pessoa de Meia-Idade , Nitrofurantoína/uso terapêutico , Prostatite/complicações
11.
J Urol ; 153(4): 1321-6, 1995 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-7869536

RESUMO

Interstitial cystitis (IC) is an inflammatory disease of the urinary bladder that has no known etiology. A microbial association with this disease has not been supported since routine cultures of urine from IC patients are usually negative. However, we have demonstrated the presence of bacterial 16S rRNA genes in bladder biopsies from 29% of patients with IC, but not from control patients with other urological diseases. The ability to identify the presence of bacterial DNA in these patients was accomplished using a sensitive and specific nested PCR method capable of amplifying 16S rRNA genes from a wide variety of bacterial genera. Cloning and sequencing of 16S rRNA gene fragments amplified from bladder tissue of IC patients showed that these genes were derived from genera representing Gram-negative bacteria. In addition to the molecular data, a novel finding of 0.22 micron. filterable forms has been isolated in culture from the biopsy tissue of 14 of 14 IC patients and from 1 of 15 controls. The forms contain nucleic acids and resemble cell wall-deficient bacteria in gross morphology; however, their swirled myelin-like ultrastructure is unusual and suggests a heretofore unclassified microbe. These results demonstrate for the first time an association of Gram-negative bacterial DNA and filterable forms with affected bladder tissue from patients with IC.


Assuntos
Bactérias/isolamento & purificação , Cistite/microbiologia , Bexiga Urinária/microbiologia , Southern Blotting , DNA Bacteriano/análise , Amplificação de Genes , Humanos , Reação em Cadeia da Polimerase , RNA Ribossômico 16S/análise , Sensibilidade e Especificidade
12.
Immunobiology ; 192(1-2): 65-76, 1994 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-7538488

RESUMO

Antibodies to partially purified E. coli 06 35-40 KDa porin trimers recognized the reactive epitopes in the intact porin surface molecule present in various wild-type, heterologous, urinary pathogens. The presence of lipopolysaccharide in the membrane did not shield the antibody binding sites. The reactivity was shown to be specific for porins since LPS-absorbed porin antisera reacted with porins on immunoblots and showed no reactivity with LPS. Additionally, the cross-reactions were abolished by absorption of the porin antisera with E. coli 06 containing porin trimers. These data strengthen the rationale for exploring the enhancement of immunoprotection by monoclonal antibodies to specific immunoreactive antigens in the porin molecule.


Assuntos
Anticorpos Antibacterianos/imunologia , Escherichia coli/imunologia , Porinas/imunologia , Infecções Urinárias/microbiologia , Animais , Bactérias/imunologia , Bactérias/isolamento & purificação , Sítios de Ligação de Anticorpos/imunologia , Reações Cruzadas , Ensaio de Imunoadsorção Enzimática , Epitopos/imunologia , Escherichia coli/isolamento & purificação , Imunofluorescência , Humanos , Lipopolissacarídeos/imunologia , Coelhos , Urina/microbiologia
13.
Immunol Invest ; 23(3): 223-30, 1994 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-8070850

RESUMO

Electroeluted outer membrane proteins [(EOmp), (35-37 KDa, porins)] were highly immunogenic in New Zealand White rabbits. An ELISA peak titer of 51,200 to EOmp as compared to 6,400 for non-eluted outer membrane protein (Omp) was demonstrated. EOmp enhanced the antigenicity of Omp possibly due to epitopes which were masked in the non-eluted antigen. Non-eluted, partially purified, Omp elicited high anti-lipopolysaccharide (LPS) titers (25,600); however, electroelution diminished LPS contamination (non detection of LPS chemically and on immunoblots) and greatly reduced the anti-LPS titer (400). It is biologically significant that anti-EOmp antibodies cross-reacted with wild-type urinary pathogens. Specificity for Omp reactivity was demonstrated by ELISA and on immunoblots with absorbed EOmp (LPS-free) antisera. These findings strengthen the rationale for exploring the protective potential of anti-Omp antibodies.


Assuntos
Antígenos de Bactérias/imunologia , Proteínas da Membrana Bacteriana Externa/imunologia , Animais , Proteínas da Membrana Bacteriana Externa/isolamento & purificação , Reações Cruzadas , Eletroforese em Gel de Poliacrilamida , Ensaio de Imunoadsorção Enzimática , Escherichia coli/imunologia , Imunoglobulina G/biossíntese , Lipopolissacarídeos/imunologia , Coelhos
14.
Infect Immun ; 61(5): 2122-30, 1993 May.
Artigo em Inglês | MEDLINE | ID: mdl-8478102

RESUMO

Monophosphoryl lipid A (MLA), derived either from Salmonella minnesota or Salmonella typhimurium, was tested for its ability to alter Candida albicans mannan (MAN)-specific suppression. Since we showed previously that naive mice injected intravenously (i.v.) with MAN developed suppressor T cells capable of down-regulating delayed-type hypersensitivity when transferred to immunized recipients, MLA was tested for its ability to influence suppressor activity in the donors of suppressor cells. T-lymphocyte-enriched suspensions from donor mice treated with MLA, especially that derived from S. typhimurium, 2 or 3 days after the injection of MAN lost the ability to suppress delayed-type hypersensitivity when transferred to immunized mice. Transferable suppressor activity was reduced but not always completely abrogated when donor animals were treated with MLA 1 day following the administration of MAN. In several experiments, S. minnesota MLA also abrogated activity, but it was not effective in other transfer experiments. In a different type of experiment, MLA was given to immunized mice which had been suppressed directly with MAN. Mice were immunized, either by the introduction of C. albicans intragastrically followed by inoculation intradermally (i.d.) or by two i.d. inoculations, and MAN-specific suppressor cells were induced in such animals by the i.v. injection of MAN 1 day before the first or second i.d. inoculation in animals given intragastric plus i.d. inoculations and those given two i.d. inoculations, respectively. MLA was administered to such mice prior to the i.v. injection of MAN, on the same day, or 1 to 4 days thereafter. S. typhimurium MLA, especially when given to mice 2 days following the administration of MAN, caused a partial abrogation of suppressor activity. Overall, however, MLA, at 5 to 100 micrograms, had variable and minimal effects on suppressor activity in immunized mice suppressed by the i.v. administration of MAN. In summary, MLA is clearly capable of abrogating MAN-induced suppression when given to nonimmunized animals in which MAN-specific suppressor cells had been induced, but its efficacy in immunized animals suppressed by the i.v. administration of MAN was marginal.


Assuntos
Candida albicans/imunologia , Candidíase/imunologia , Hipersensibilidade Tardia/imunologia , Tolerância Imunológica/efeitos dos fármacos , Lipídeo A/análogos & derivados , Mananas/imunologia , Linfócitos T Reguladores/imunologia , Animais , Feminino , Imunização Passiva , Lipídeo A/farmacologia , Masculino , Camundongos , Camundongos Endogâmicos CBA , Salmonella typhimurium/imunologia
15.
J Clin Invest ; 88(6): 1848-55, 1991 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-1752946

RESUMO

Malaria parasites, unable to synthesize purine de novo, use host-derived hypoxanthine preferentially as purine source. In a previous study (1990. J. Biol. Chem. 265:6562-6568), we noted that xanthine oxidase rapidly and completely depleted hypoxanthine in human erythrocytes, not by crossing the erythrocyte membrane, but rather by creating a concentration gradient which facilitated hypoxanthine efflux. We therefore investigated the ability of xanthine oxidase to inhibit growth of FCR-3, a chloroquine-resistant strain of Plasmodium falciparum in human erythrocytes in vitro. Parasites were cultured in human group O+ erythrocytes in medium supplemented, as required, with xanthine oxidase or chloroquine. Parasite viability was assessed by uptake of radiolabeled glycine and adenosine triphosphate-derived purine into protein and nucleic acid, respectively, by nucleic acid accumulation, by L-lactate production, and by microscopic appearance. On average, a 90% inhibition of growth was observed after 72 h of incubation in 20 mU/ml xanthine oxidase. Inhibition was notably greater than that exerted by 10(-7) M chloroquine (less than 10%) over a comparable period. The IC50 for xanthine oxidase was estimated at 0.2 mU/ml, compared to 1.5 x 10(-7) M for chloroquine. Inhibition was completely reversed by excess hypoxanthine, but was unaffected by oxygen radical scavengers, including superoxide dismutase and catalase. The data confirms that a supply of host-derived hypoxanthine is critical for nucleic acid synthesis in P. falciparum, and that depletion of erythrocyte hypoxanthine pools of chloroquine-resistant malaria infection in humans. of chloroquine-resistant malaria infection in humans.


Assuntos
Eritrócitos/parasitologia , Plasmodium falciparum/efeitos dos fármacos , Xantina Oxidase/farmacologia , Animais , Células Cultivadas , Cloroquina/farmacologia , Relação Dose-Resposta a Droga , Glicina/metabolismo , Humanos , Hipoxantina , Hipoxantinas/metabolismo , Hipoxantinas/farmacologia , Plasmodium falciparum/crescimento & desenvolvimento , Purinas/metabolismo , Superóxido Dismutase/farmacologia , Xantina Oxidase/uso terapêutico
17.
Infect Immun ; 58(8): 2613-20, 1990 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-2142482

RESUMO

We have shown previously that CBA/J mice immunized with Candida albicans developed delayed hypersensitivity (DH) demonstrable with mannan (MAN) extracted from the same organism and that the intravenous (i.v.) injection of MAN prior to or during the immunization phase resulted in the suppression of the MAN-specific DH response. In this study, we demonstrate that MAN-induced suppression of DH is a T-lymphocyte-mediated phenomenon. Suppressor cells induced in vivo by the i.v. injection of MAN into naive mice 1 to 7 days prior to harvest were passaged through nylon wool, treated with various surface-specific antibodies and complement, and then injected i.v. into immunized syngeneic recipients. Enrichment of splenic T cells by passage over nylon wool and transfer of the nylon-wool-nonadherent populations to immunized recipient mice suppressed DH in a dose-dependent manner. Depletion of Thy+ or Lyt-2+ cells from nylon-wool-nonadherent populations regularly ablated the ability of such suspensions to transfer suppression. Treatment of the same transfer suspensions with anti-Lyt-1 had variable effects, suggesting that the surface density of the Lyt-1 antigen was not as constant from population to population as was the Lyt-2 antigen. In addition, C. albicans MAN-induced suppressor cells were able to suppress DH demonstrable with Candida tropicalis MAN in animals immunized with C. tropicalis. Suppression of DH by MAN in this model, therefore, is mediated by Thy+ Lyt-2+ lymphocytes.


Assuntos
Candida albicans/imunologia , Hipersensibilidade Tardia/imunologia , Mananas/imunologia , Linfócitos T Reguladores/imunologia , Animais , Antígenos Ly/imunologia , Antígenos de Superfície/imunologia , Candidíase/imunologia , Feminino , Imunização , Masculino , Camundongos , Camundongos Endogâmicos CBA , Fenótipo
18.
J Biol Chem ; 265(12): 6562-8, 1990 Apr 25.
Artigo em Inglês | MEDLINE | ID: mdl-1691171

RESUMO

Uptake and release of purines by red blood cells has been shown to be markedly sensitive to changes in pH, inorganic phosphate (Pi), and oxygen concentration (Berman, P., Black, D., Human, L., and Harley, E. (1988) J. Clin. Invest. 82, 980-986). The mechanism of this regulation has been further studied. We have shown that incubation of red cells in medium containing xanthine oxidase rapidly and completely depletes intracellular hypoxanthine and causes accumulation of 5-phosphoribosyl 1-pyrophosphate (PRPP) at physiological Pi concentrations. Hypoxanthine release from intracellular IMP is strictly dependent on PRPP depletion, induced by either alkalinizing the cells or by adding excess adenine. Xanthine oxidase abolishes this dependence. Oxygen depletion enhances adenine uptake and prevents hypoxanthine release. The results suggest that hypoxanthine release is governed by PRPP-dependent recycling of hypoxanthine to IMP. We propose that PRPP accumulation in red cells is regulated by a substrate cycle, comprising hypoxanthine, IMP, and inosine. Cycle flux is controlled by Pi inhibition and 2,3-bisphosphoglycerate activation of purine-5'-nucleotidase, which converts IMP to inosine. Oxypurine cycling may account for the sensitive control of purine uptake and release by changes in pH and oxygen tension that occur physiologically.


Assuntos
Eritrócitos/metabolismo , Hipoxantinas/sangue , Pentosefosfatos/sangue , Fosforribosil Pirofosfato/sangue , Transporte Biológico/efeitos dos fármacos , Cromatografia Líquida de Alta Pressão , Humanos , Hipoxantina , Técnicas In Vitro , Cinética , Modelos Biológicos , Nucleotidases/sangue , Oxigênio/sangue , Pressão Parcial , Nucleotídeos de Purina/sangue , Nucleotídeos de Purina/isolamento & purificação , Purinas/sangue , Purinas/isolamento & purificação , Xantina Oxidase/sangue
19.
J Clin Invest ; 82(3): 980-6, 1988 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-2458389

RESUMO

The effect of pH, PO2, and inorganic phosphate on the uptake and metabolism of hypoxanthine by erythrocytes has been studied. Uptake of hypoxanthine and accumulation of inosine 5'-monophosphate (IMP) were markedly increased at acid pH, high external phosphate concentrations, and low PO2. Release of accumulated IMP as hypoxanthine occurred at alkaline pH values and low external phosphate concentrations. Conditions favoring IMP accumulation gave rise, in the absence of hypoxanthine, to a corresponding increase in 5'-phosphoribosyl-1-pyrophosphate. Intracellular phosphate concentrations were markedly pH dependent and a model is presented whereby hypoxanthine uptake and release are controlled by intracellular concentrations of inorganic phosphate and 2,3-bisphosphoglycerate. These allosteric effectors influence, in opposing ways, two enzymes governing IMP accumulation, namely 5'-phosphoribosyl-1-pyrophosphate synthetase and 5'-nucleotidase. These metabolic properties suggest that the erythrocyte could play a role in the removal of hypoxanthine from anoxic tissue.


Assuntos
Eritrócitos/metabolismo , Hipoxantinas/sangue , Oxigênio/sangue , Fosfatos/farmacologia , Difosfato de Adenosina/sangue , Trifosfato de Adenosina/sangue , Eritrócitos/efeitos dos fármacos , Humanos , Concentração de Íons de Hidrogênio , Inosina Monofosfato/sangue , Oxigênio/fisiologia , Pressão Parcial , Fosfatos/sangue , Fosforribosil Pirofosfato/biossíntese
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...