Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 18 de 18
Filtrar
1.
Trop Med Int Health ; 11(4): 452-61, 2006 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-16553928

RESUMO

OBJECTIVE: To document the cost incurred by the Tanzanian government by changing the policy on first-line treatment of malaria, from chloroquine to sulfadoxine-pyrimethamine. METHODS: Costs were analysed from the perspective of the Ministry of Health and included all sources of funding. Costs external to the public health sector (e.g. private and community costs) were not included. The base case analysis adopted an incremental rather than a full cost approach, assuming that an organizational infrastructure was already in place. However, specific attention was paid to the burden placed on National Malaria Control Program staff. We also costed activities planned but not implemented to estimate the total expense for an 'ideal' process. RESULTS: Total costs were Tsh 795 million (USD 813,743), with the largest proportion accounted for by training. Costs of the policy change process were equivalent to about 4% of annual government and donor expenditure on malaria and to about 1% of overall public expenditure on health. A number of planned activities were not implemented; including these would bring the total cost to Ts 880 million (USD 896,130). CONCLUSION: On top of extra costs for the drugs themselves, a change in treatment policy requires time, resources and substantial management capacity at national and local level. A better understanding of these issues and the costs involved benefits countries planning and implementing policy change.


Assuntos
Antimaláricos/uso terapêutico , Custos de Cuidados de Saúde , Política de Saúde/economia , Malária Falciparum/tratamento farmacológico , Amodiaquina/economia , Amodiaquina/uso terapêutico , Antimaláricos/economia , Cloroquina/economia , Cloroquina/uso terapêutico , Protocolos Clínicos , Combinação de Medicamentos , Educação em Saúde/economia , Pessoal de Saúde/economia , Pessoal de Saúde/educação , Humanos , Malária Falciparum/economia , Malária Falciparum/epidemiologia , Guias de Prática Clínica como Assunto , Pirimetamina/economia , Pirimetamina/uso terapêutico , Sulfadoxina/economia , Sulfadoxina/uso terapêutico , Tanzânia/epidemiologia
2.
Ann Trop Med Parasitol ; 97(1): 69-73, 2003 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-12662424

RESUMO

Hospital-acquired infections (HAI) are a major and largely preventable cause of morbidity and morbidity worldwide. Very few reports on the prevalence of HAI in sub-Saharan Africa have been published and most of those that have appeared in the press have focused on surgical-wound infection. In the present, questionnaire-based, point-prevalence study, in which the doctor on the ward round was used as the primary informant, the prevalences of all HAI among all the inpatients at a tertiary referral hospital in northern Tanzania were estimated. On the day of the study, there were 412 inpatients (in 15 ward areas) and 61 cases of HAI were identified, giving an overall HAI prevalence of 14.8%. The prevalences of HAI were particularly high in the medical intensive-care unit (40%), the surgical (orthopaedic and general surgery) wards (36.7%), and one of the general medical wards (22.2%). Factors associated with a patient having a HAI were hospitalization for >30 days [odds ratio (OR) = 4.07; 95% confidence interval (CI) = 2.07-7.99]; being a patient on the orthopaedic and general surgical ward known as 'Surgical 2' (OR = 2.14; CI = 1.02-4.46); and being referred from another health facility (OR = 1.90; CI = 1.02-3.42). The most commonly identified HAI in the hospital were urinary-tract infections (14 cases), followed by surgical-wound infections (10 cases) and then lower respiratory-tract infections (six cases). Twenty HAI were 'unspecified'. The study was rapid and cheap to carry out. The results not only gave a baseline estimate of HAI in the study setting but also identified key areas for interventions to reduce HAI.


Assuntos
Infecção Hospitalar/epidemiologia , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Criança , Pré-Escolar , Feminino , Humanos , Lactente , Tempo de Internação , Masculino , Pessoa de Meia-Idade , Prevalência , Análise de Regressão , Infecções Respiratórias/epidemiologia , Infecção da Ferida Cirúrgica/epidemiologia , Inquéritos e Questionários , Tanzânia/epidemiologia , Infecções Urinárias/epidemiologia
4.
J Health Serv Res Policy ; 5(1): 42-8, 2000 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-10787587

RESUMO

Five recent economic evaluations comparing hospital at home schemes with acute hospital care faced remarkably similar problems. This paper outlines these problems and considers what strategies can be derived from these experiences, which will be relevant to economic evaluations of other aspects of the organisation of care, particularly those crossing the interfaces between primary and secondary health care or the interface between health and social services. The difficulties experienced can be divided into conceptual and practical problems. Conceptual problems were primarily associated with issues of context and related to the choice of comparator, capacity constraints and size of schemes, and the choice between a short or a long run perspective. Practical problems were connected with the time at which schemes were evaluated, the type of clinical study alongside which studies were conducted and the types of data available for use in the analysis. Strategies which can be pursued in conducting economic evaluations of organisational change include giving greater attention to conceptual and hence contextual problems as well as reporting these contextual issues in detail, accepting the need for repeated economic evaluations as organisational changes become more widespread and considering carefully the clinical study design where economic evaluations of organisational change are conducted alongside. These strategies are of importance not just to those conducting economic evaluations but also to those funding appraisals of changes in the organisation of care. Use of different strategies such as those suggested here should be evaluated.


Assuntos
Serviços Hospitalares de Assistência Domiciliar/economia , Avaliação de Programas e Projetos de Saúde/economia , Atenção à Saúde/economia , Atenção à Saúde/organização & administração , Serviços Hospitalares de Assistência Domiciliar/organização & administração , Hospitalização/economia , Inovação Organizacional/economia , Reino Unido
5.
J Health Serv Res Policy ; 5(1): 49-58, 2000 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-10787588

RESUMO

OBJECTIVES: To summarise the findings from a comprehensive review of research on the effects of the three main elements of the quasi-market reforms of the UK National Health Service (NHS) introduced in 1991/92: General practices becoming fundholders by volunteering to purchase elective care for their patients; Health authorities becoming purchasers of emergency, unplanned and elective services, together with a range of alternatives to fundholding operating under their auspices; The conversion of providers of hospital and community health services to NHS trusts separate from their local health authorities. METHODS: Published and unpublished studies which included any data on the impact of the three main planks of the quasi-market changes, produced between 1991 and late 1998, were identified using a combination of electronic databases, library catalogues at the King's Fund, London, bibliographies, reference lists of individual studies, a survey of NHS directors of public health and consultations with subject area experts. Each main element of the quasi-market was assessed in relation to its impact on: efficiency (primarily productivity); equity; quality; choice and responsiveness; and accountability. RESULTS: There was relatively little measurable change that could be related unequivocally to the core mechanisms of the quasi-market. CONCLUSIONS: The incentives were generally too weak and the constraints too strong to generate the consequences predicted by either proponents or critics of the quasi-market. On the other hand, the way in which the NHS operates was changed irrevocably by the reforms.


Assuntos
Reforma dos Serviços de Saúde/tendências , Marketing de Serviços de Saúde/tendências , Orçamentos/tendências , Medicina de Família e Comunidade/organização & administração , Medicina de Família e Comunidade/tendências , Reforma dos Serviços de Saúde/organização & administração , Pesquisa sobre Serviços de Saúde , Marketing de Serviços de Saúde/organização & administração , Programas Nacionais de Saúde/organização & administração , Programas Nacionais de Saúde/tendências , Inovação Organizacional , Administração da Prática Médica/organização & administração , Administração da Prática Médica/tendências , Reino Unido
6.
Drug Dev Ind Pharm ; 26(4): 423-8, 2000 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-10769784

RESUMO

Suitable analytical methods are required for quantitative determination of trace levels of ingredients in samples obtained for purposes of cleaning validation. We describe below an atomic absorption method for the quantitation of cisplatin, an antineoplastic agent, in aqueous samples. Cisplatin was reacted with diethyldithiocarbamic acid (DDTC), sodium salt, to yield a platinum-DDTC (Pt-DDTC) complex. The Pt-DDTC chelate was extracted into methylene chloride, the extract was mixed with acetonitrile, and the platinum content was then determined using a Zeeman atomic absorption (AA) spectrophotometer. The extraction conditions and AA experimental conditions were set up such that the detection level could be extended to 0.5 ng/ml. Reproducible results were obtained at a quantitative working standard concentration of 5 PPB. The absorbance response was found to be a linear function of cisplatin concentration in the region between 0.5 PPB and 20 PPB, which is about 10% to 400% of the target analyte concentration of 5 PPB. The target analyte concentration was set at 5 PPB such that it was at least 10 times the detection limit of about 0.5 PPB.


Assuntos
Antineoplásicos/análise , Cisplatino/análise , Espectrofotometria Atômica , Detergentes/química , Contaminação de Equipamentos/prevenção & controle , Sensibilidade e Especificidade , Água
7.
Drug Dev Ind Pharm ; 26(4): 429-40, 2000 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-10769785

RESUMO

A high-performance liquid chromatographic (HPLC) method is described for the determination of residual levels of cisplatin from extracts of surfaces with very low surface area; from extracts of surfaces of coupons made of Teflon (polytetrafluoroethylene, PTFE), stainless steel, and glass; and in aqueous solution collected after rinsing equipment and parts. Initially, the method was developed to determine cisplatin at concentrations ranging from 20 to 200 ng/ml by direct injection. Retaining the same method conditions, the scope of the method was expanded by the addition of a sample preconcentration step, allowing analyses at levels ranging from 0.5 ng to 20 ng/ml. Preconcentration is necessary for the determination of cisplatin in rinse waters at a quantifiable concentration of about 2 PPB. Under these conditions, the detection limit is about 0.2 to 0.3 ng/ml. Residual cisplatin on different types of surfaces, including surfaces with very low surface area, can be determined by swabbing each test surface with a derivatizing solution. The cisplatin recovered in the swabbing solution can be analyzed by HPLC using direct injection or preconcentration, depending on the expected level of cisplatin in the sample. Initial methods were developed to quantitate at a cisplatin concentration of about 100 PPB or higher in solution extracted from surfaces. However, when surface areas are limited because of the size of the parts, solution concentration becomes very low as a result of the minimum volume required for extraction. To support the application of swabbing techniques to surface analysis, stainless steel, Teflon, and glass surfaces were spiked with cisplatin at 2.5 to 20 ng/cm2. Satisfactory overall recoveries of 90% +/- 10% were obtained from all surfaces. Cisplatin has no ultraviolet/visible (UV/Vis) spectral-active functional group that can be used to detect low levels of cisplatin. Hence, diethyldithiocarbamate (DDTC) was used as a derivatizing agent to increase sensitivity to UV absorption at 340 nm. Diethyldithiocarbamate forms complexes with the platinum in cisplatin to yield a platinum-DDTC (Pt-DDTC) complex with a high molar-extinction coefficient. The Pt(DDTC)2 complex thus formed was chromatographically separated and the quantitated by comparison of its detector response to that of a similarly derivatized standard preparation. DDTC also has application as a cleaning agent for cisplatin (e.g., for production equipment cleaning, spill cleanup). Destruction of cisplatin can be affected by the reaction of cisplatin with this cleaning agent. Derivatization of cisplatin will convert active cisplatin to platinum-DDTC on surfaces or in solution. Final cleaning can be accomplished using a water-for-injection rinse. After such a cleaning process, the rinse water, when collected and analyzed, showed levels of free cisplatin less than the detection concentration of 0.2 PPB and a total platinum concentration less than 10 PPB as Pt-DDTC complex.


Assuntos
Antineoplásicos/análise , Cromatografia Líquida de Alta Pressão , Cisplatino/análise , Detergentes , Contaminação de Equipamentos/prevenção & controle , Sensibilidade e Especificidade , Água
9.
Ann Surg Oncol ; 5(3): 279-86, 1998.
Artigo em Inglês | MEDLINE | ID: mdl-9607632

RESUMO

BACKGROUND: Previous studies demonstrated that excess IL-6 production correlated with the metastatic potential of rat hepatocellular carcinoma cells. In the work reported here a retroviral construct containing the gene for murine IL-6 was introduced into otherwise nonmetastatic tumor cells to directly determine the effect of IL-6 overexpression on tumor metastatic potential. METHODS: The clonal cell lines 1682.C.2.9.L0 (L0, poorly metastatic) and 1682.C.2.9.L10 (L10, highly metastatic) were selected from a parental hepatocellular carcinoma induced in ACI rats by feeding an ethionine-containing diet. Viral supernatant was used to infect the PA317 amphotropic cell line, and retrovirus produced from these cells infected the poorly metastatic L0 hepatocellular carcinoma cell line. Neomycin-resistant cells were selected in G418 and designated L0-IL-6. RESULTS: As determined by bioassay, L0 cells produce 10 +/- 1.2 U/mL IL-6 in culture, whereas L10 cells release 95 +/- 11 U/mL (P < 0.01, Student's t-test). Retroviral-mediated IL-6 gene transfer resulted in the production of 1266 +/- 48 U/mL IL-6 by L0-IL-6 cells under identical culture conditions. When an inoculum of 5 x 10(6) cells is injected subcutaneously, both L0 and L10 cell lines result in primary tumors with equivalent rates of growth; only L10 cells metastasize to the lung, however. A similar inoculation of L0-IL-6 cells produced local tumors in all 24 animals tested. Interestingly, 15 of 24 (62%) animals presented with metastatic nodules in the abdominal cavity, whereas no such tumors were found in animals receiving L10 cells. CONCLUSION: Overexpression of IL-6 increases metastatic potential of tumor cells, with preferential metastases to the abdominal cavity when compared with tumor cells elaborating endogenous IL-6.


Assuntos
Regulação Neoplásica da Expressão Gênica/genética , Interleucina-6/genética , Neoplasias Hepáticas Experimentais/genética , Neoplasias Hepáticas Experimentais/imunologia , Metástase Neoplásica/genética , Metástase Neoplásica/imunologia , Neoplasias Abdominais/secundário , Animais , Carcinógenos , Modelos Animais de Doenças , Etionina , Neoplasias Hepáticas Experimentais/induzido quimicamente , Neoplasias Hepáticas Experimentais/patologia , Masculino , Ratos , Ratos Endogâmicos ACI , Células Tumorais Cultivadas
10.
Soc Sci Med ; 46(4-5): 567-79, 1998.
Artigo em Inglês | MEDLINE | ID: mdl-9460836

RESUMO

A number of studies have suggested that inequalities in the distribution of income may be an important cause of variations in the average level of population health among rich industrial nations. However, what is missing from the debate so far is any systematic review of evidence about the relationship between different measures of income distribution and indicators of population health. This paper aims to bridge that gap. First, it summarizes the recent English language literature on this topic and illustrates the methodological problems that weaken the inferences that can be derived from it. Secondly, it presents new empirical estimates of the relationship between different measures of income distribution, infant mortality and life expectancy based on the most authoritative data published to date. In contrast to most earlier studies, we find very little support for the view that income inequality is associated with variations in average levels of national health in rich industrial countries. Some possible explanations for these differences are outlined.


Assuntos
Indicadores Básicos de Saúde , Renda , Países Desenvolvidos , Países em Desenvolvimento , Família , Saúde Global , Humanos , Lactente , Mortalidade Infantil , Expectativa de Vida , Análise Multivariada , Análise de Regressão
11.
Health Econ ; 5(4): 353-62, 1996.
Artigo em Inglês | MEDLINE | ID: mdl-8880172

RESUMO

This paper examines the development of contracting within the NHS on the basis of the data collected as part of a national survey of English District Health Authorities carried out in late 1994. The paper starts with a discussion of the background to contracting and its evolution during the first 4 years of the NHS internal market. The second section describes the methodology employed in the national survey. The third section presents the results of the survey alongside a discussion of their relevance in terms of the economics of contracting. This section shows the prevalence of different types of contracts and discusses the emergence of the most common type-sophisticated block contracts. Details are provided of how contracts deal with issues such as the measurement of activity, the pricing of projected activity and of activity variances (mainly at marginal cost), as well as the involvement of clinicians in contracting. Other topics explored include the management of extra contractual referrals, contracting for specialized services, arbitration arrangements, the purchaser efficiency index and contracts with the independent sector. The final section offers some concluding thoughts on the current state and future of contracting in the NHS.


Assuntos
Serviços Contratados/economia , Competição Econômica/estatística & dados numéricos , Medicina Estatal/economia , Serviços Contratados/estatística & dados numéricos , Economia Médica , Inglaterra , Cuidado Periódico , Pesquisas sobre Atenção à Saúde , Humanos , Negociação , Métodos de Controle de Pagamentos , Encaminhamento e Consulta/economia , Encaminhamento e Consulta/estatística & dados numéricos , Regionalização da Saúde/economia , Especialização , Medicina Estatal/tendências
12.
Arch Surg ; 131(4): 360-5, 1996 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-8615719

RESUMO

BACKGROUND: The phenotypic characteristics that allow some tumor cells to metastasize have not been fully identified. The production and/or response of tumor cells to various growth factors have been shown to distinguish cells of differing metastatic potentials. OBJECTIVES: To determine (1) whether rat hepatocellular carcinoma cell lines produce interleukin-6 (IL-6) and (2) whether production of IL-6 correlates with either metastatic potential or tumorigenicity. METHODS: The clonal cell lines 1682.C.2.9.L0 (poorly metastatic) and 1682.C.2.9.L10 (highly metastatic) were selected from a parental hepatocellular carcinoma induced in ACI rats by feeding an ethionine-containing diet and adapted to growth in vitro. RESULTS: Both cell lines resulted in primary tumors with equal frequency and developed a 40-mm nodule in a similar period time, when an inoculum of 5 X 10(6) cells was injected subcutaneously; however, only L10 cells metastasized to the lung. These cell lines did not demonstrate differential expression of several antigens noted to correlate with metastatic potential, including CD44 variant glycoprotein, p53, transferrin receptor, and E-cadherin. In contrast, L0 cells produced less than 10 U of IL-6 per milliliter in culture (as determined by bioassay using 7TD1 cells), whereas L10 cells released more than 95 U of this cytokine per milliliter under identical culture conditions (P<.01, Student's t test). In addition, serum concentrations of IL-6 were elevated in animals bearing L10-induced primary tumors but not in those with L0-induced tumors of comparable mass. Exogenous addition of IL-6 to both tumor cell lines had no effect on the rate of growth in vitro, supporting the similar the tumorigenic potentials observed in vivo. CONCLUSION: Excess IL-6 production appears to identify cells with metastatic potential and does not appear to be essential to the establishment of a primary tumor.


Assuntos
Interleucina-6/biossíntese , Neoplasias Hepáticas Experimentais/metabolismo , Neoplasias Hepáticas Experimentais/patologia , Neoplasias Hepáticas/metabolismo , Neoplasias Hepáticas/patologia , Animais , Linhagem Celular/efeitos dos fármacos , Células Clonais/efeitos dos fármacos , Interleucina-6/farmacologia , Masculino , Metástase Neoplásica , Ratos , Ratos Endogâmicos
13.
J Surg Res ; 59(6): 636-43, 1995 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-8538159

RESUMO

The pivotal role played by the macrophage in specific and nonspecific immunity suggests that the physiological status of the macrophage may effect the overall regulation of the host defense system. Many studies have evaluated macrophages as effector cells by examining expression of surface markers, cytokine release, or tumor killing in the presence of challenge to host defenses. In this report, the physiological parameter of mitochondrial respiration in freshly isolated rat macrophages is shown to be regulated upon activation in vivo. Assay conditions for the reduction of MTT [3-(4,5-dimethylthiazol-2)-2,5-diphenyltetrazolium bromide] in rat macrophages were optimized and used to quantitate electron transport chain activity as a measure of mitochondrial respiration. Corynebacterium parvum administration significantly increased the activity of the mitochondrial electron transport chain in both peritoneal (120% increase, 0.18 +/- .01 vs 0.40 +/- .03, P < 0.01) and liver macrophages (143% increase, 0.12 +/- .02 vs 0.30 +/- .06, P < 0.01) as detected by augmented MTT reduction. It is demonstrated further that MTT reduction is distinct from the respiratory burst activity of macrophages and supports the mitochondrial localization of intracellular MTT reduction in this cell type. These results demonstrate that electron transport chain activity is a physiological indicator of macrophage activation.


Assuntos
Macrófagos/fisiologia , Animais , Sobrevivência Celular/efeitos dos fármacos , Corantes , Transporte de Elétrons , Cinética , Fígado/citologia , Macrófagos/efeitos dos fármacos , Macrófagos Peritoneais/efeitos dos fármacos , Masculino , Oxirredução , Propionibacterium acnes/fisiologia , Ratos , Ratos Endogâmicos ACI , Valores de Referência , Explosão Respiratória , Sais de Tetrazólio/metabolismo , Sais de Tetrazólio/farmacologia , Tiazóis/metabolismo , Tiazóis/farmacologia
14.
Proc Natl Acad Sci U S A ; 84(24): 8834-8, 1987 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-3321056

RESUMO

Insulin treatment enhances casein kinase II (CKII) activity in 3T3-L1 mouse adipocytes and H4-IIE rat hepatoma cells, the magnitude of the activation varying from 30% to 150%. Activation of CKII was apparent after 5 min of exposure of 3T3-L1 cells to insulin, was maximal by 10 min, and persisted through 90 min. The insulin-stimulated activity was inhibited by low concentrations of heparin and was stimulated by spermine. Activation of CKII was effected by physiological concentrations of insulin (EC50 = 0.15 nM), suggesting that the effect is a true insulin response and not one mediated through insulin-like growth factor receptors. Epidermal growth factor (100 ng/ml for 10 min) also activated CKII in A431 human carcinoma cells, which is consistent with other observations that insulin and epidermal growth factor may have some common effects. Insulin stimulation of CKII activity was due to an increase in the maximal velocity of the kinase; the apparent Km for peptide substrate was not altered. Enhanced activity did not appear to result from increased synthesis of CKII protein, because cycloheximide did not block the effect and because an immunoblot developed with antiserum to CKII showed no effect of insulin on the cytosolic concentration of CKII. Because insulin-stimulated CKII activity was maintained after chromatography of cell extracts on Sephadex G-25, it is unlikely that the effect is mediated by a low-molecular-weight activator of the kinase. Rather, the results are consistent with the possibility that insulin activates CKII by promoting a covalent modification of the kinase.


Assuntos
Fator de Crescimento Epidérmico/farmacologia , Insulina/farmacologia , Proteínas Quinases/metabolismo , Animais , Caseína Quinases , Linhagem Celular , Núcleo Celular/enzimologia , Cicloeximida/farmacologia , Citosol/enzimologia , Ativação Enzimática/efeitos dos fármacos , Heparina/farmacologia , Técnicas de Imunoadsorção , Camundongos
15.
J Biol Chem ; 262(19): 9136-40, 1987 Jul 05.
Artigo em Inglês | MEDLINE | ID: mdl-3474230

RESUMO

The specificity of casein kinase II has been further defined by analyzing the kinetics of phosphorylation reactions using a number of different synthetic peptides as substrates. The best peptide substrates are those in which multiple acidic amino acids are present on both sides of the phosphorylatable serine or threonine. Acidic residues on the NH2-terminal side of the serine (threonine) greatly enhance the kinetic constants but are not absolutely required. Acidic residues on the COOH-terminal side of the serine (threonine) are absolutely required. One position for which the occupation of an acidic residue is especially critical is the position located 3 residues to the COOH terminus of the phosphate acceptor site, although the presence of an acidic amino acid in the positions that are 4 or 5 residues removed may also provide an appropriate structure that will serve as a substrate for the kinase. Aspartate serves as a better amino acid determinant than glutamate. A relatively short sequence of amino acids surrounding the phosphate acceptor site appears to serve as the basis for the specificity of casein kinase II. The peptides in this study were also assayed with casein kinase I and the casein kinase from the mammary gland so that the specificities of these kinases could be compared to that of casein kinase II.


Assuntos
Proteínas Quinases/metabolismo , Sequência de Aminoácidos , Animais , Caseína Quinases , Bovinos , Cinética , Glândulas Mamárias Animais/enzimologia , Especificidade por Substrato
16.
Plant Physiol ; 79(2): 480-4, 1985 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-16664435

RESUMO

Cell wall composition of a stable suspension of proso millet (Panicum miliaceum L. cv Abarr) cells is similar to those of tissues and cell suspensions of other graminaceous species. Extraction of hemicelluloses with step-wise increasing concentrations of alkali yields materials that, like those of embryonal cells of maize coleoptiles, comprise mostly glucuronoarabinoxylan, xyloglucan, and small amounts of (1-3),(1-4)-beta-d-glucan. As in the walls of embryonal cells of the maize coleoptile, 5-arabinosyl and 3-arabinosyl comprise much higher proportions of the total hemicellulosic sugars than in walls of developed or elongated cells. Unlike cells of many dicotyledonous species, millet cells do not elongate or undergo observable differentiation during the stationary phase of culture, and consequently, their wall composition is remarkably consistent throughout the culture cycle. The proso millet cell suspension culture constitutes a reasonable model for study of cell wall biogenesis in embryonal cells of a graminaceous species, but because of marked changes in the composition of hemicelluloses in these species during cell enlargement, additional model systems should be sought.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...