Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 52
Filtrar
1.
J Basic Microbiol ; 61(11): 960-981, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34608659

RESUMO

Environmental protection from emerging pollutants has become a significant challenge for mankind as an increasing number of contaminants, including synthetic dyes and polycyclic aromatic hydrocarbons (PAHs), represent a serious risk to ecological and environmental balance. Most synthetic dyes have complex aromatic structures and are resistant to degrade by classical approaches, such as physical and chemical processes, including adsorption, chemical coagulation, flocculation, ion exchange, membrane separation, froth flotation, and reverse osmosis. Enzymes-assisted catalytic transformation of pollutants has become a potential alternative to classical methods because of their ability to react with complex compounds, a quick degradation rate, and producing less harmful by-products. Plant peroxidases, and microbial laccase and lignin-degrading peroxidases (manganese and lignin peroxidase) have gained significant attention for treating aromatic waste due to their capability of oxidizing and detoxifying a wide range of recalcitrant xenobiotics, including PAHs and synthetic dyes. Peroxidases being efficient biocatalysts detoxify an array of toxic compounds by simple free-radical mechanism resulting in the formation of oxidized and depolymerized products of significantly reduced toxicity. Moreover, it is an ecofriendly and economically favorable approach towards the biodegradation of recalcitrant and toxic industrial waste. Among microbial and plant peroxidases, bacterial enzymes have broad substrate specificity and can transform a wide range of recalcitrant substrates. Ligninolytic enzymes oxidize the aromatic ring into quinones and acids by producing free hydroxyl radicals instead of dihydrodiols and mineralize aromatic hydrocarbon in combination with cytochrome P450, monooxygenases, and epoxide hydrolases. In the review, an attempt has been made to provide detailed knowledge about the availability of inexpensive peroxidases sources, their mechanism of action, and degradation potential. The present review summarizes the exploitation of peroxidases from plants, bacteria, and fungus (manganese peroxidase, lignin peroxidase, and laccases) for detoxification and degradation of textile dyes as well as PAHs. Conclusively, peroxidases have great potential to react with almost all classes of synthetic dyes and most PAHs due to broad substrate specificity and transformed them into less harmful metabolites.


Assuntos
Corantes/metabolismo , Hidrocarbonetos Policíclicos Aromáticos/metabolismo , Proteínas de Bactérias/metabolismo , Biodegradação Ambiental , Catálise , Proteínas Fúngicas/metabolismo , Lacase/metabolismo , Peroxidases/metabolismo , Proteínas de Plantas/metabolismo , Eliminação de Resíduos
2.
Pharmazie ; 69(5): 335-9, 2014 May.
Artigo em Inglês | MEDLINE | ID: mdl-24855823

RESUMO

Solution thermodynamics and solubilization behavior of diclofenac sodium (DS) in binary mixture of Transcutol-HP and water is not reported in the literature so far. Therefore, the aim of the present study was to investigate the solution thermodynamics and solubilization behavior of DS in mono-solvents and various Transcutol-water mixtures at 298.15-333.15 K. The mole fraction solubility of DS was determined by shake flask method and thermodynamic parameters (enthalpies and entropies) were calculated with the help of the modified Apelblat model. The experimental solubility data of DS in all sample matrices was found to be correlated well with the modified Apelblat model with correlation coefficients of 0.9950-0.9990. Absolute relative deviation was found to be less than 3% in most of the Transcutol-water mixtures at each temperature studied. The mole fraction solubility of DS was observed to be highest in pure Transcutol (0.139 at 298.15 K) as compared to pure water and other Transcutol-water mixtures. The enthalpies and entropies for DS dissolution were observed as positive values for all cosolvent mixtures which indicated that the dissolution of DS is endothermic and an entropy-driven process. Based on solubility data, DS was considered as sparingly soluble in pure water and freely soluble in Transcutol. These results indicated that Transcutol could be used as an alternate of ethanol, propylene glycol and polyethylene glycol to enhance aqueous solubility of DS. These preliminary studies could be useful in formulation development of DS especially in terms of liquid dosage forms and injectable formulations.


Assuntos
Anti-Inflamatórios não Esteroides/química , Diclofenaco/química , Etilenoglicóis/química , Algoritmos , Química Farmacêutica , Lipossomos , Nanopartículas , Solubilidade , Termodinâmica , Água
3.
Braz J Biol ; 84: e281217, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-39109717

RESUMO

The Astragalus grahamianus (AG) Royle ex. Benth is traditionally used for the treatment of various human disorders. The current research work is aimed to explore the neuroprotective anti-Parkinson effects of various fractions of Astragalus grahamianus (A. grahamianus). Fine powder of Astragalus grahamianus was extracted with 70% methanol and then fractionated with various solvents on the basis of polarity. Standard protocols were used to investigate the bioactive constituents present in the various plant fractions. In-vitro antioxidant potential of various fractions was checked using diverse free radicals. In-vivo rats model was used to determined the neuroprotective effects of methanol fraction of A. grahamianus. The results revealed that various fractions of A. grahamianus contain flavonoids, cardiac glycosides, steroids, gums, terpenes, proteins, and carbohydrates except chloroform fraction lake the presence of steroids, cardiac glycosides, gums and saponins, aqueous fraction of steroids, terpenoids, gums and saponins, n-Hexane fraction steroids, carbohydrates, alkaloids, gums and flavonoids. The highest amount of total phenolic contents was found in AGME (32.67 ± 2.3 mg GAE / g). The AGME also showed enhanced free radicals cations potential against DPPH, ABTS and H2O2, respectively. The correlation between AOA (antioxidant activity) and TPC (total phenolic contents) revealed to be substantial. Relative R2 values for ABTS, H2O2, and DPPH activity are 0.9974, 0.9845, and 0.9678, respectively. The in-vivo neuroprotective activities showed significant results. Our findings highlight significant antioxidant, and neuroprotective possessions of AGME attributed to powerful bioactive compounds.


Assuntos
Antioxidantes , Astrágalo , Fármacos Neuroprotetores , Extratos Vegetais , Animais , Extratos Vegetais/farmacologia , Extratos Vegetais/química , Antioxidantes/farmacologia , Antioxidantes/análise , Fármacos Neuroprotetores/farmacologia , Astrágalo/química , Ratos , Masculino , Ratos Wistar
4.
J Pediatr Endocrinol Metab ; 35(3): 325-332, 2022 Mar 28.
Artigo em Inglês | MEDLINE | ID: mdl-34905667

RESUMO

BACKGROUND: Classical homocystinuria (HCU) is an autosomal recessive inborn error of metabolism, which is caused by the cystathionine-ß-synthase (CBS: encoded by CBS) deficiency. Symptoms of untreated classical HCU patients include intellectual disability (ID), ectopia lentis and long limbs, along with elevated plasma methionine, and homocysteine. METHODS: A total of 429 ID patients (age range: 1.6-23 years) were sampled from Northern areas of Punjab, Pakistan. Biochemical and genetic analyses were performed to find classical HCU disease in ID patients. RESULTS: Biochemically, nine patients from seven unrelated families were identified with high levels of plasma methionine and homocysteine. Targeted exonic analysis of CBS confirmed seven causative homozygous mutations; of which three were novel missense mutations (c.451G>T; p.Gly151Trp, c.975G>C; p.Lys325Asn and c.1039 + 1G>T splicing), and four were recurrent variants (c.451 + 1G>A; IVS4 + 1 splicing, c.770C>T; p.Thr257Met, c.808_810del GAG; p.Glu270del and c.752T>C; p.Leu251Pro). Treatment of patients was initiated without further delay with pyridoxine, folic acid, cobalamin, and betaine as well as dietary protein restriction. The immediate impact was noticed in behavioral improvement, decreased irritability, improved black hair color, and socialization. Overall, health outcomes in this disorder depend on the age and symptomatology at the time of treatment initiation. CONCLUSIONS: With personalized treatment and care, such patients can reach their full potential of living as healthy a life as possible. This screening study is one of the pioneering initiatives in Pakistan which would help to minimize the burden of such treatable inborn errors of metabolism in the intellectually disabled patients.


Assuntos
Cistationina beta-Sintase , Homocistinúria , Adolescente , Adulto , Povo Asiático , Criança , Pré-Escolar , Cistationina beta-Sintase/genética , Cistationina beta-Sintase/metabolismo , Homocistinúria/diagnóstico , Homocistinúria/genética , Homocistinúria/terapia , Humanos , Lactente , Mutação , Paquistão/epidemiologia , Adulto Jovem
5.
East Mediterr Health J ; 17(11): 882-6, 2011 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-22276499

RESUMO

Excess lead in drinking water is a neglected source of lead toxicity in Pakistan. A cross-sectional survey in 2007/08 was made of water samples from drinking water sources in Karachi, a large industrial city. This study aimed to compare lead levels between untreated ground water and treated surface (tap) water in 18 different districts. Of 216 ground and surface water samples collected, 86% had lead levels higher than the World Health Organization maximum acceptable concentration of l0 ppb. Mean lead concentration in ground water [146 (SD 119) ppb] was significantly higher than in surface water [77.1 (SD 54) ppb]. None of the 18 districts had a mean lead level of ground or surface water below the WHO cut-off and ground water sources in 9 districts had a severe level of contamination (>150 ppb). Urgent action is needed to eliminate sources of contamination.


Assuntos
Água Potável/análise , Exposição Ambiental/análise , Chumbo/isolamento & purificação , Paquistão
6.
Int J Biol Macromol ; 150: 861-870, 2020 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-32057879

RESUMO

Rapid industrialization is polluting the water resources and is becoming a serious environmental issue. In present study, the adsorption-desorption behavior of Direct Orange-26 (DO-26), Direct Red-31 (DR-31), Direct Blue-67 (DB-67) and Ever direct Orange-3GL (EDO-3) dyes on to native, modified rice husk (MRH), polyvinyl alcohol (PVA), carboxymethyl cellulose (CMC) and alginate (ALG) immobilized biomasses were investigated under different experimental conditions. For adsorbent modification, physical and chemical treatments were performed. The results showed that HCl pre-treatment considerably increased the sorption capacity of dyes versus native biomass. The sorption data were optimized using pseudo 1st order, intra-particle diffusion, pseudo 2nd order and Elovich models. The results revealed that the two-step rate equation was followed for the desorption kinetics of dyes. The involvement of -OH (hydroxyl), -COOH (carboxylic) and -NH2 (amino) groups in the adsorption of dyes onto biomasses was shown by FTIR analysis. Studies exhibited that among adsorbents employed, the MRH has the excellent potential for the dyes degradation from textile effluents.


Assuntos
Alginatos/química , Carboximetilcelulose Sódica/química , Corantes/química , Oryza/química , Álcool de Polivinil/química , Adsorção , Compostos Azo , Biomassa , Concentração de Íons de Hidrogênio , Imobilização/métodos , Cinética , Poluentes Químicos da Água , Purificação da Água
7.
Eur J Clin Microbiol Infect Dis ; 28(5): 547-51, 2009 May.
Artigo em Inglês | MEDLINE | ID: mdl-19020911

RESUMO

The molecular analysis of methicillin-resistant Staphylococcus aureus (MRSA) from 98 children admitted to the Children's Hospital of Michigan, Detroit, MI, with serious MRSA infections during 2006-2007 was correlated with risk factors, clinical features, and antibiotic susceptibility testing (ABST) results. Isolates were characterized by staphylococcal cassette chromosome (SCC) mec type, the presence of Panton-Valentine leukocidin (PVL) genes, repetitive sequence (rep) polymerase chain reaction (PCR) and pulsed-field gel electrophoresis (PFGE), requirement for surgical intervention, antibiograms, and response to therapy. rep-PCR was more rapid than PFGE typing and correlated well. SCCmec type IV-containing isolates caused 92.8% of all infections, but the demographics and diseases associated with subtypes IVa and IVd differed. Subtype IVa (all PFGE type USA300 and PVL-positive) was identified in 81/93 (87.1%) of patients with community-onset (CO) MRSA, including 21/35 of those with risk factors for health care-associated (HA) infection. All other clones were PVL-negative. Subtype IVd (10 isolates; 9 USA800 and 1 eMRSA15) caused mainly HA-MRSA and no skin and soft tissue infections (SSTI). Seven classic HA-MRSA strains (SCCmec types II [6; 3 USA100 and 3 USA600] and III [1; USA200]) caused HA and hospital-onset (HO) infections. Surgical intervention was required in 68/81 patients infected with USA300 and 8/17 of the others. Most USA300 were susceptible (S) to clindamycin (CD) and patients were treated with CD alone or in combination. The other isolates were generally treated with vancomycin (VA) alone or in combination.


Assuntos
Antibacterianos/farmacologia , Staphylococcus aureus Resistente à Meticilina/isolamento & purificação , Infecções Estafilocócicas/microbiologia , Adolescente , Proteínas de Bactérias/genética , Toxinas Bacterianas/genética , Técnicas de Tipagem Bacteriana , Criança , Criança Hospitalizada , Pré-Escolar , Análise por Conglomerados , Impressões Digitais de DNA , DNA Bacteriano/genética , Exotoxinas/genética , Feminino , Humanos , Lactente , Recém-Nascido , Leucocidinas/genética , Masculino , Staphylococcus aureus Resistente à Meticilina/classificação , Staphylococcus aureus Resistente à Meticilina/genética , Michigan , Testes de Sensibilidade Microbiana , Epidemiologia Molecular , Fatores de Risco , Infecções Estafilocócicas/patologia , Infecções Estafilocócicas/fisiopatologia
14.
J Am Coll Cardiol ; 18(7): 1694-701, 1991 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-1960315

RESUMO

High speed rotational coronary atherectomy was undertaken using the Rotablator in 42 patients who were suboptimal candidates for balloon angioplasty. Most patients (71%) had diffuse coronary artery disease, defined as a stenosis greater than 1 cm in length. Previous restenosis after balloon angioplasty was present in 21% and 10% had an ostial lesion. Adjunctive balloon angioplasty was not used to reduce residual stenosis after atherectomy. The procedure was successful in 76% of patients. Procedural success was achieved in 92% of patients with a lesion less than or equal to 1 cm in length, but in only 70% of patients with a lesion greater than 1 cm in length (p less than 0.01). One patient sustained abrupt closure of the target vessel, resulting in emergency bypass surgery and death. Small non-Q wave myocardial infarction occurred in eight patients (19%) and was associated with a longer lesion. The mean peak creatine kinase value in patients with non-Q wave myocardial infarction was 683 U/liter. Transient regional wall motion abnormalities were noted on the postatherectomy left ventricular angiogram in four of the eight patients with non-Q wave myocardial infarction. Follow-up angiography (at a mean interval of 6.2 +/- 2.6 months) was performed in 91% of patients and revealed restenosis (greater than 50% narrowing) in 59% The resistance rate was 22% for short lesions (less than or equal to 1 cm) and 75% for long lesions (greater than 1 cm) (p less than 0.05). In this study, the results of high speed rotational coronary atherectomy were strongly influenced by lesion length.(ABSTRACT TRUNCATED AT 250 WORDS)


Assuntos
Angioplastia Coronária com Balão/normas , Doença das Coronárias/terapia , Angioplastia Coronária com Balão/efeitos adversos , Angioplastia Coronária com Balão/instrumentação , Angiografia Coronária , Doença das Coronárias/diagnóstico por imagem , Doença das Coronárias/epidemiologia , Feminino , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Infarto do Miocárdio/epidemiologia , Infarto do Miocárdio/etiologia , Complicações Pós-Operatórias/epidemiologia , Complicações Pós-Operatórias/etiologia , Valor Preditivo dos Testes , Recidiva , Fatores de Risco
15.
Acta Chim Slov ; 62(4): 849-58, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26680712

RESUMO

Pure and Gd doped Zinc Oxide (ZnO) nanoparticles were synthesized by sonochemical method using different surfactants (PVP/CTAB). The nanoparticles were characterized by powder X-ray diffraction (PXRD), fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), particle size analysis by DLS technique and UV-Visible spectroscopy. The effect of Gd doping and nature of surfactants on crystallite size, morphology and band gap of ZnO nanoparticles have been investigated. In addition to this, the effect of nature of surfactant on amount of dopant inserted in the ZnO lattice was also studied.

16.
J Neuroimmunol ; 101(1): 7-14, 1999 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-10580808

RESUMO

CD40 can participate in inflammatory processes after binding its cognate ligand (CD40L). We found that fetal human astrocytes constitutively express CD40 mRNA and protein. Upon incubating cultures with proinflammatory cytokines (TNF-alpha, IL-1beta and IFN-gamma) or with lipopolysaccharide (LPS), CD40 expression was increased. No change in CD40 expression was noted in astrocyte cultures incubated with IL-6, HIV or gp41. Astrocytes also showed increased release of proinflammatory cytokines TNF-alpha, IL-1beta and IL-6 after incubation with CD40L peptide. These observations suggest a role for CD40 in central nervous system (CNS) inflammation and that CD40/CD40L autocrine or paracrine pathways may mediate this role.


Assuntos
Astrócitos/química , Antígenos CD40/análise , Citocinas/farmacologia , Ligante de CD40 , Células Cultivadas , Feminino , Feto/química , Proteína Glial Fibrilar Ácida/análise , HIV/fisiologia , Humanos , Lipopolissacarídeos/farmacologia , Glicoproteínas de Membrana/farmacologia , Gravidez
17.
Psychoneuroendocrinology ; 27(8): 907-20, 2002 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-12383452

RESUMO

BACKGROUND: An association between abnormal changes in reproductive endocrine function during the perimenopause and the onset of depression in some women has been suggested but remains controversial. METHODS: We examined basal plasma hormone levels in two samples of women with well characterized, first onset depression (major or minor) during the perimenopause and matched comparison groups of asymptomatic women. Results were compared by analysis of variance. RESULTS: No significant diagnosis-related differences were observed in plasma hormone measures of the following: follicle stimulating hormone (FSH), luteinizing hormone (LH), estradiol (E2), estrone (E1), total (T) or free testosterone (FT), or the E2/LH ratio. We did identify significantly lower morning plasma dehydroepiandrosterone (DHEA) and its sulphated metabolite DHEA-S (but not cortisol) levels in the depressed women compared to the non-depressed comparison group. Women with hot flushes (regardless of the presence of depression) were significantly older than women without flushes, had significantly higher plasma levels of FT, LH and FSH, and had significantly lower E2/LH ratios. CONCLUSIONS: Women with first onset depression during the perimenopause are not distinguished from controls on the basis of basal hormone measures of ovarian estrogens, testosterone, or gonadotropins. However, perimenopause-related changes in E2 may interact with low levels of DHEA in some women to increase their vulnerability to develop depression. In contrast to perimenopause-related vasomotor symptoms, depression during the perimenopause is not associated with a simple hormone deficiency state. The relatively low levels of E2 and E1 in the depressed women may have met statistical significance in a much larger and homogenous sample.


Assuntos
Climatério , Depressão/sangue , Hormônios/sangue , Adulto , Desidroepiandrosterona/sangue , Sulfato de Desidroepiandrosterona/sangue , Estradiol/sangue , Estrona/sangue , Feminino , Hormônio Foliculoestimulante/sangue , Fogachos/sangue , Humanos , Hidrocortisona/sangue , Hormônio Luteinizante/sangue , Pessoa de Meia-Idade , Testosterona/sangue
18.
Pediatr Infect Dis J ; 19(10): 954-8, 2000 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-11055595

RESUMO

BACKGROUND: Yersinia enterocolitica can cause illness ranging from self-limited enteritis to life-threatening systemic infection. The present study was undertaken to review the epidemiology, clinical manifestations, complications and outcome of Y. enterocolitica enteritis in children seen at a large children's hospital. METHODS: The project consisted of a retrospective chart review of medical and microbiologic records of all children with stool cultures positive for Y. enterocolitica during a 7-year period. RESULTS: The review included 142 patients with Y. enterocolitica enteritis. Patients' ages ranged from 18 days to 12 years, and the majority (85%) were younger than 1 year. Most patients presented during November, December and January. History of exposure to chitterlings (raw pork intestines) at home was elicited in 25 of 30 cases. Y. enterocolitica accounted for 12.6% (142 of 1,120) of all bacterial intestinal pathogens isolated during the study period. Blood cultures were positive in 7(9%) of 78 patients; 6 were younger than 1 year and one 12-year-old had sickle cell disease. Of 132 isolates tested all were susceptible to trimethoprim-sulfamethoxazole, tobramycin and gentamicin; the majority were susceptible to cefotaxime (99%), ceftazidime (89%) and cefuroxime (88%). All bacteremic patients responded to cefotaxime treatment. Follow-up evaluation of 40 ambulatory patients revealed no difference in clinical improvement between those treated with oral trimethoprim-sulfamethoxazole (17 of 23) and those who were not treated (8 of 17) (P = 0.1). CONCLUSION: Y. enterocolitica is an important cause of enteritis in our young patient population during the winter holidays. Exposure of infants to chitterlings appears to be a risk factor. Infants younger than 3 months are at increased risk for bacteremia. Cefotaxime is effective in the treatment of Y. enterocolitica bacteremia; however, the role of oral antibiotics in the management of enteritis needs further evaluation.


Assuntos
Enterite/epidemiologia , Enterite/microbiologia , Yersiniose/epidemiologia , Yersinia enterocolitica/isolamento & purificação , Adolescente , Antibacterianos/uso terapêutico , Bacteriemia/tratamento farmacológico , Bacteriemia/epidemiologia , Bacteriemia/microbiologia , Criança , Pré-Escolar , Fezes/microbiologia , Feminino , Hospitais Pediátricos , Humanos , Lactente , Recém-Nascido , Masculino , Prevalência , Estudos Retrospectivos , Fatores de Risco , Yersiniose/tratamento farmacológico , Yersiniose/microbiologia , Yersiniose/fisiopatologia
19.
QJM ; 88(8): 571-80, 1995 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-7648244

RESUMO

The classical cause of postpartum hypopituitarism is Sheehan's syndrome, in which an obstetric catastrophe is associated with hypotension. However, with improvements in obstetric care, the most common cause now may be lymphocytic hypophysitis. Five women with postpartum hypopituitarism, whose symptoms occurred during or immediately after pregnancy, had detailed endocrine and pituitary imaging for the duration of follow-up. Two presented with visual symptoms, and three with non-specific illnesses related to varying deficiencies of anterior pituitary hormones. Four were unable to lactate, and four were initially amenorrhoeic. Initially, four of the five women had enlarged pituitary glands on magnetic resonance imaging. Four have to some extent recovered pituitary function. One patient had associated thyroiditis: in two cases antinuclear antibodies became positive during follow-up, and in one of these dsDNA antibody was also detected. In no case were pituitary antibodies detected. None had complicated pregnancies or deliveries, and the two who had caesarean sections had no episodes of hypotension. The presentation of secondary hypothyroidism combined with ACTH deficiency in four of the five women strongly suggests lymphocytic hypophysitis. This diagnosis should be considered in postpartum women with general malaise and persistent amenorrhoea, as well as in women who develop visual impairment in the last trimester of pregnancy without antecedent pituitary disease. A conservative policy of management of the pituitary enlargement should be pursued as this resolves.


Assuntos
Hipopituitarismo/etiologia , Linfocitose/complicações , Transtornos Puerperais/complicações , Hormônio Adrenocorticotrópico/deficiência , Adulto , Amenorreia/etiologia , Feminino , Hormônio Liberador de Gonadotropina , Humanos , Inflamação/complicações , Inflamação/diagnóstico , Insulina , Doenças da Hipófise/complicações , Doenças da Hipófise/diagnóstico , Gravidez , Hormônio Liberador de Tireotropina , Tomografia Computadorizada por Raios X , Transtornos da Visão/etiologia
20.
Methods Mol Biol ; 6: 261-9, 1990.
Artigo em Inglês | MEDLINE | ID: mdl-21390612

RESUMO

A number of different methods have been developed for the enucleation of cells, particularly mammalian cells. Centrifugation of cells adhering to a surface may lead to the nucleus being drawn out from the cytoplasm, resulting in the formation of an enucleated cell or cytoplast and a nucleus surrounded by a thin layer of cytoplasm bounded by a plasma membrane (mini-cell). In those cases where cells do not adhere sufficiently firmly to a surface, enucleation has been achieved by centrifugation in density gradients. This method takes advantage of the differing densities of the nucleus and the cytoplasm. When cells are centrifuged at high speed in a suitable density gradient, the nucleus and the cytoplasm tend to float in those regions of the gradient matching their own densities. If the distance between the regions with densities corresponding to that of the cytoplasm and that of the nucleus is relatively long, considerable stretching forces are generated. Under optimum conditions, this force is usually sufficient to enucleate a high percentage of the cells. The use of density gradients and high-speed centrifugation for generating cytoplasts and mini-cells is much less explored in plant than in mammalian cells.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA