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1.
Public Health ; 168: 59-66, 2019 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-30685600

RESUMEN

OBJECTIVES: There is a high prevalence of depressive disorders among children and adolescents globally, accounting for 45% of disability-adjusted life years among 10- to 24-year-olds. Although it has been recognized as a major public health concern in Pakistan, there have been no studies exploring the development or cross-cultural validation of instruments for screening and assessing the severity of adolescent depression. Therefore, the present study was designed to validate the Urdu translation of the Patient Health Questionnaire for Adolescents (PHQ-A) among Pakistani children and adolescents. STUDY DESIGN: This is a cross-sectional study. METHODS: A total of 452 children and adolescents responded to a survey comprising demographic characteristics, the Urdu translation of PHQ-A, and the Urdu version of Strengths and Difficulties Questionnaire (SDQ). It was hypothesized that total scores on the PHQ-A would correlate significantly with the SDQ scores. Reliability analysis and exploratory factor analyses were carried out using SPSS v.20. Additional confirmatory factor analyses were conducted using the FACTOR program. RESULTS: No floor and ceiling effects were reported for PHQ-A total scores. Factor analysis confirmed good results for language interchangeability and unidimensionality among the sampled adolescents. Similarly, the findings showed good internal consistency (Cronbach's alpha 0.76), test-retest reliability (intraclass correlation coefficient = 0.61; 0.53-0.68), and concurrent validity. CONCLUSION: The Urdu translation of the PHQ-A is a valid and reliable instrument for assessing depression among Pakistani adolescents, based on the Diagnostic and Statistical Manual diagnosis criteria.


Asunto(s)
Comparación Transcultural , Depresión/diagnóstico , Tamizaje Masivo , Cuestionario de Salud del Paciente , Traducciones , Adolescente , Niño , Estudios Transversales , Análisis Factorial , Femenino , Humanos , Masculino , Pakistán , Reproducibilidad de los Resultados , Servicios de Salud Escolar
2.
Adv Orthop ; 2012: 528423, 2012.
Artículo en Inglés | MEDLINE | ID: mdl-22655202

RESUMEN

Articular cartilage (AC) injury is a common disorder. Numerous techniques have been employed to repair or regenerate the cartilage defects with varying degrees of success. Three commonly performed techniques include bone marrow stimulation, cartilage repair, and cartilage regeneration. This paper focuses on current level of evidence paying particular attention to cartilage regeneration techniques.

3.
Plant Biol (Stuttg) ; 14(1): 24-32, 2012 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-21973219

RESUMEN

ARF1 (ADP-ribosylation factor 1) and SAR1 (secretion-associated RAS super family) are involved in the formation and budding of vesicles throughout plant endomembrane systems. The molecular mechanisms of this transport have been studied extensively in mammalian and yeast cells. However, very little is known about the mechanisms of coat protein complex (COP) formation and recruitment of COP-vesicle cargoes in plants. To provide insights into vesicular trafficking in Pisum sativum L., we investigated mRNA and protein expression patterns of ARF1 and SAR1 in roots and shoots at early growth stages and in the de-etiolation process. We showed that ARF1 was concentrated mostly in the crude Golgi fractions, and SAR1 was concentrated predominantly in the crude ER fractions of de-etiolated shoots. ARF1 and SAR1 proteins were several times more abundant in shoots relative to roots. In total protein homogenates, the expression level of SAR1 and ARF1 was higher in shoots of dark-grown pea plants than light-grown plants. In contrast, ARF1 was higher in roots of light-grown pea relative to roots of dark-grown pea. With ageing, the ARF1 mRNA in roots was reduced, while SAR1 expression increased. Unlike ARF1 transcripts, ARF1 protein levels did not fluctuate significantly in root and shoot tissue during early development. The relative abundance of SAR1 protein in root tissues may suggest a high level of vesicular transport from the ER to the Golgi. Experimental results suggested that white light probably affects the regulation of ARF1 and SAR1 protein levels. On the other hand, short-term white light affects SAR1 but not ARF1.


Asunto(s)
Factor 1 de Ribosilacion-ADP/biosíntesis , Pisum sativum/metabolismo , Proteínas R-SNARE/biosíntesis , Factor 1 de Ribosilacion-ADP/genética , Factor 1 de Ribosilacion-ADP/metabolismo , Proteínas Adaptadoras del Transporte Vesicular/metabolismo , Retículo Endoplásmico/metabolismo , Proteínas de Unión al GTP/metabolismo , Aparato de Golgi/metabolismo , Luz , Proteínas de la Membrana/metabolismo , Pisum sativum/genética , Raíces de Plantas/genética , Raíces de Plantas/metabolismo , Brotes de la Planta/genética , Brotes de la Planta/metabolismo , Transporte de Proteínas , Proteínas R-SNARE/genética , Proteínas R-SNARE/metabolismo , Transcripción Genética
4.
Sci Total Environ ; 389(2-3): 270-6, 2008 Jan 25.
Artículo en Inglés | MEDLINE | ID: mdl-17919685

RESUMEN

A large number of epidemiologic studies have been undertaken to identify potential risk factors for cancer, amongst which the association with cadmium has received considerable attention. There is compelling evidence in support of positive associations between cadmium and risk of lung cancer. In present study we measured the concentration of Cd in whole blood and scalp hair samples of 120 male lung cancer patients (smokers) and 150 controls or referents (smokers and nonsmokers) from different cities of Pakistan. Both referents and patients were of same age group (ranged 40-70 years), socio-economic status, localities and dietary habits. The scalp hair and whole blood samples were oxidized by 65% nitric acid: 30% hydrogen peroxide (2:1) ratio in microwave oven. To check the validity of the proposed method, a conventional wet acid digestion method was used to obtain total Cd concentration in certified samples of human hair BCR 397 and Clincheck control-lyophilized human whole blood. All digests were analyzed for Cd concentration by electrothermal atomic absorption spectrometer (ETAAS). The results of this study showed that the average Cd concentration was higher in the blood and scalp hair of lung cancer patients at different stages as compared to controls (p<001). The smoker referents have high level of Cd in both biological samples as compared to nonsmoker subjects. These results illustrate that the patients who continued smoking after confirmed diagnosis of lung cancer have 34.2-67.26 and 22.4-57.3% more Cd in blood samples and scalp hair than lung cancer patients who cease smoking. This study is compelling evidence in support of positive associations between cadmium, cigarette smoking and lung cancer risk.


Asunto(s)
Cadmio/análisis , Carcinógenos Ambientales/análisis , Cabello/química , Neoplasias Pulmonares/sangre , Fumar/sangre , Adulto , Anciano , Cadmio/sangre , Cadmio/toxicidad , Carcinógenos Ambientales/toxicidad , Humanos , Neoplasias Pulmonares/etiología , Neoplasias Pulmonares/metabolismo , Neoplasias Pulmonares/patología , Masculino , Persona de Mediana Edad , Estadificación de Neoplasias , Pakistán , Cuero Cabelludo/química , Fumar/efectos adversos , Fumar/metabolismo , Espectrofotometría Atómica/métodos , Distribución Tisular
5.
EMBO J ; 20(23): 6751-60, 2001 Dec 03.
Artículo en Inglés | MEDLINE | ID: mdl-11726511

RESUMEN

Binding to Golgi membranes of ADP ribosylation factor 1 (ARF1) is the first event in the initiation of COPI coat assembly. Based on binding studies, a proteinaceous receptor has been proposed to be critical for this process. We now report that p23, a member of the p24 family of Golgi-resident transmembrane proteins, is involved in ARF1 binding to membranes. Using a cross-link approach based on a photolabile peptide corresponding to the cytoplasmic domain of p23, the GDP form of ARF1 (ARF1-GDP) is shown to interact with p23 whereas ARF1-GTP has no detectable affinity to p23. The p23 binding is shown to localize specifically to a 22 amino acid C-terminal fragment of ARF1. While a monomeric form of a non-photolabile p23 peptide does not significantly inhibit formation of the cross-link product, the corresponding dimeric form does compete efficiently for this interaction. Consistently, the dimeric p23 peptide strongly inhibits ARF1 binding to native Golgi membranes suggesting that an oligomeric form of p23 acts as a receptor for ARF1 before nucleotide exchange takes place.


Asunto(s)
Factor 1 de Ribosilacion-ADP/química , Factor 1 de Ribosilacion-ADP/metabolismo , Citoplasma/metabolismo , Aparato de Golgi/metabolismo , Proteínas de la Membrana/metabolismo , Receptores Citoplasmáticos y Nucleares , Secuencia de Aminoácidos , Sitios de Unión , Reactivos de Enlaces Cruzados/farmacología , Dimerización , Relación Dosis-Respuesta a Droga , Inhibidores Enzimáticos/farmacología , Guanosina Difosfato/metabolismo , Humanos , Membranas Intracelulares/metabolismo , Luz , Proteínas de la Membrana/química , Modelos Biológicos , Datos de Secuencia Molecular , Péptidos/química , Unión Proteica , Estructura Terciaria de Proteína , Proteínas Recombinantes/metabolismo , Tiocianatos/farmacología
6.
Plant Mol Biol ; 30(6): 1195-205, 1996 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-8704129

RESUMEN

The stability of the psbA mRNA increases during barley chloroplast development eventually reaching a half-life of over 40 h. Translation of psbA mRNA is also regulated in a complex way. Sequence-specific RNA binding proteins may modulate the translation or stability of the psbA mRNA during chloroplast development. UV cross-linking assays revealed that chloroplast proteins of 37 and 38 kDA bind specifically to the 3' end of psbA transcripts and not to the 5' end of psbA or rbcL transcripts. The two RNA-binding proteins were partially purified by ammonium sulfate precipitation followed by heparin agarose chromatography. Deletion and site-directed mutation analysis demonstrated that the 37/38RNPs bind in a 30 nucleotide region immediately downstream from the translation termination codon and upstream of sequences capable of forming a stem-loop structure in the 3' end of psbA transcripts. Single-base changes that diminish the binding of the 37RNP also reduce binding of the 38RNP suggesting that these proteins may bind as a heterodimer. The 37/38RNPs that bind within the 3' end of psbA transcripts could modulate transcription termination, translation or mRNA stability.


Asunto(s)
Cloroplastos/metabolismo , Hordeum/genética , Proteínas del Complejo del Centro de Reacción Fotosintética/genética , ARN Mensajero/metabolismo , ARN de Planta/metabolismo , Proteínas de Unión al ARN/metabolismo , Secuencia de Bases , Datos de Secuencia Molecular , Conformación de Ácido Nucleico , Complejo de Proteína del Fotosistema II , Unión Proteica , ARN Mensajero/química , ARN de Planta/química
7.
J Coll Physicians Surg Pak ; 6(1): 58-61, 1996.
Artículo en Inglés | MEDLINE | ID: mdl-12346518

RESUMEN

PIP: 244 fourth- and fifth-year medical students of Sindh Medical College, Karachi, completed questionnaires during November-December 1994 designed to assess their knowledge and attitudes toward HIV/AIDS. 96.7% correctly answered survey questions on the cause of AIDS. 87.7% correctly responded on the existence of HIV transmission through blood transfusion, 96.3% on transmission through sexual contact, and 77% on mother-to-child transmission. 25% of respondents believed that people with AIDS should not be allowed to use common toilets and that health personnel should attend such patients only while wearing special clothing. 72.1% were aware of the HIV antibody test for diagnosis. Further, 85% had correct knowledge on counseling to family members of HIV-infected individuals to avoid blood and body secretions, sexual activity, and condom use. 27% incorrectly believed that HIV-infected children should be removed from school and 34% did not know that HIV-infected persons remain healthy for a long period of time.^ieng


Asunto(s)
Síndrome de Inmunodeficiencia Adquirida , Actitud , Consejo , Atención a la Salud , Infecciones por VIH , Conocimiento , Estudiantes de Medicina , Instituciones de Atención Ambulatoria , Asia , Conducta , Países en Desarrollo , Enfermedad , Educación , Salud , Planificación en Salud , Organización y Administración , Pakistán , Psicología , Estudiantes , Virosis
8.
Plant Mol Biol ; 29(3): 567-77, 1995 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-8534853

RESUMEN

ADP-ribosylation factor (ARF) is a highly conserved, low molecular mass (ca. 21 kDa) GTP-binding protein that has been implicated in vesicle trafficking and signal transduction in yeast and mammalian cells. However, little is known of ARF in plant systems. A putative ARF polypeptide was identified in subcellular fractions of the green alga Chlamydomonas reinhardtii, based on [32P]GTP binding and immunoblot assays. A cDNA clone was isolated from Chlamydomonas (Arf1), which encodes a 20.7 kDa protein with 90% identity to human ARF1. Northern blot analyses showed that levels of Arf1 mRNA are highly regulated during 12 h/12 h light/dark (LD) cycles. A biphasic pattern of expression was observed: a transient peak of Arf1 mRNA occurred at the onset of the light period, which was followed ca. 12 h later by a more prominent peak in the early to mid-dark period. When LD-synchronized cells were shifted to continuous darkness, the dark-specific peak of Arf1 mRNA persisted, indicative of a circadian rhythm. The increase in Arf1 mRNA at the beginning of the light period, however, was shown to be light-dependent, and, moreover, dependent on photosynthesis, since it was prevented by DCMU. We conclude that the biphasic pattern of Arf1 mRNA accumulation during LD cycles is due to regulation by two different factors, light (which requires photosynthesis) and the circadian clock. Thus, these studies identify a novel pattern of expression for a GTP-binding protein gene.


Asunto(s)
Chlamydomonas reinhardtii/genética , Chlamydomonas reinhardtii/metabolismo , Proteínas de Unión al GTP/biosíntesis , Proteínas de Unión al GTP/genética , Factor 1 de Ribosilacion-ADP , Factores de Ribosilacion-ADP , Secuencia de Aminoácidos , Animales , Secuencia de Bases , Cartilla de ADN , ADN Complementario , Diurona/farmacología , Proteínas de Unión al GTP/metabolismo , Expresión Génica/efectos de los fármacos , Expresión Génica/efectos de la radiación , Regulación de la Expresión Génica de las Plantas , Guanosina Trifosfato/metabolismo , Humanos , Cinética , Luz , Mamíferos , Datos de Secuencia Molecular , Plantas/genética , Reacción en Cadena de la Polimerasa , ARN Mensajero/biosíntesis , Saccharomyces cerevisiae/metabolismo , Homología de Secuencia de Aminoácido , Transducción de Señal
10.
J Pak Med Assoc ; 44(3): 70-1, 1994 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-8041003

RESUMEN

Urethral or cervical swab of 255 patients attending Skin and Social Hygiene Centre and found positive for gram negative intracellular diplococci on direct microscopy were inoculated on Modified New York City (MNYC) medium and chocolate (heated blood) agar for isolation of neisseria gonorrhea. Growth of N. gonorrhea was obtained in 134 (52.5%) cases. These strains were tested for penicillin susceptibility by disc diffusion method and for the production of beta-lactamase by rapid penicillinase paper strip test and rapid chromogenic cephalosporin method. Penicillin resistance was found in 31 (23%) strains, of which twelve (9%) were beta-lactamase producers (PPNG), the remaining 19 (14%) strains were penicillin resistant beta-lactamase negative (Pen RB Neg). We conclude that PPNG as well as other penicillin resistant strains (Pen RB Neg) of neisseria gonorrhea are prevalent in our country and appropriate changes in the conventional therapeutic regime are desirable.


Asunto(s)
Comparación Transcultural , Gonorrea/tratamiento farmacológico , Neisseria gonorrhoeae/efectos de los fármacos , Resistencia a las Penicilinas , Penicilinas/uso terapéutico , beta-Lactamasas/metabolismo , Cuello del Útero/microbiología , Femenino , Gonorrea/microbiología , Humanos , Masculino , Pruebas de Sensibilidad Microbiana , Neisseria gonorrhoeae/enzimología , Pakistán , Uretra/microbiología
11.
Biochim Biophys Acta ; 1179(1): 11-22, 1993 Oct 07.
Artículo en Inglés | MEDLINE | ID: mdl-8399350

RESUMEN

The primary aim of this study was to determine if small GTP-binding proteins play a role in the conspicuous and much-examined volume control process in Dunaliella salina. We confirmed the previous identification by Rodriguez et al. (Rodriguez Rosales, M.P., Herrin, D.L. and Thompson, G.A., Jr. (1992) Plant Physiol. 98, 446-451) of small GTP-binding proteins in the green alga Dunaliella salina and revealed the presence of at least five such proteins, having molecular masses of approx. 21, 28, 28.5, 29 and 30 kDa. These proteins were concentrated largely in the endoplasmic reticulum (ER) and in an intermediate density organelle fraction (GA) containing mainly Golgi vesicles, mitochondria and flagella. The chloroplast fraction and plasma membrane contained the 28-kDa GTP-binding protein exclusively, while the cytosol contained both the 28-kDa component and small amounts of a 21-kDa GTP-binding protein. Immunodetection analysis showed that the D. salina 28-kDa protein cross-reacted strongly with a polyclonal antibody raised against a Volvox carteri yptV1 type GTP-binding protein. This antibody was utilized for quantitative GTP-binding protein measurements as described below. Certain anti-GTP-binding protein antibodies derived from non-plant sources, namely, monoclonal antibodies raised against yeast and mouse ypt1 GTP-binding proteins, cross-reacted not only with the D. salina 28-kDa protein but also the 29-kDa component. The 30-kDa GTP-binding protein of D. salina did not bind the antibodies mentioned above but did cross-react with an anti-yeast ypt1 polyclonal antibody. None of the D. salina GTP-binding proteins reacted positively with polyclonal antibodies raised against SEC4, rab1 or rab6 proteins. When D. salina cells were subjected to hypoosmotic swelling by abruptly reducing the NaCl concentration of their medium from 1.7 M to 0.85 M, the increase in cell surface area was accompanied by a substantial translocation of the 28-kDa GTP-binding protein from the ER and GA fractions to the plasma membrane, chloroplast and cytosolic fractions, as determined by quantitative [32P]GTP binding and [125I]antibody binding on nitrocellulose blots. This translocation increased the content of the 28-kDa component in the plasma membrane, chloroplast and cytosol by 3-4-fold. No net movement of the 30-kDa GTP-binding protein from either the ER or GA fractions was observed following hypoosmotic shock.(ABSTRACT TRUNCATED AT 400 WORDS)


Asunto(s)
Tamaño de la Célula , Chlorophyta/metabolismo , Proteínas de Unión al GTP/metabolismo , Ósmosis , Radioisótopos de Fósforo
12.
J Biol Chem ; 268(27): 20164-9, 1993 Sep 25.
Artículo en Inglés | MEDLINE | ID: mdl-8376376

RESUMEN

Low molecular weight GTP-binding proteins and GLUT4 protein were isolated in purified plasma membrane and low density microsome fractions from rat skeletal muscle. GTP-binding proteins were detected via the ability of these proteins to bind [32P]GTP subsequent to Western blotting. GLUT4 protein was detected via the anti-GLUT4 antibody F349 subsequent to Western blotting. The possible involvement of GTP-binding proteins in the regulation of GLUT4 protein movement was investigated by examining the subcellular distribution of GTP-binding proteins and GLUT4 protein under basal conditions and following stimulation by insulin or muscle contraction. Insulin stimulation caused a 111 +/- 34.8% increase in the plasma membrane content of GTP-binding proteins which was paralleled by a 74 +/- 19.1% increase in the plasma membrane content of GLUT4 protein. The insulin-stimulated increase in plasma membrane GTP-binding proteins and GLUT4 protein occurred coincident with 27 +/- 4.6 and 33 +/- 7.4% decreases, respectively, in the low density microsome content of these proteins. In addition, muscle contraction significantly increased the plasma membrane content of GTP-binding proteins (63 +/- 18.1%) and GLUT4 protein (67 +/- 22.2%). However, with muscle contraction the concentrations of GTP-binding proteins and GLUT4 protein were not altered in low density microsome fractions. The similar patterns with which the GTP-binding proteins and GLUT4 protein responded to stimulation by insulin and muscle contraction suggests a possible, but yet unidentified functional relationship between these proteins.


Asunto(s)
Desoxiglucosa/metabolismo , Proteínas de Unión al GTP/metabolismo , Glucosa/metabolismo , Guanosina Trifosfato/metabolismo , Insulina/farmacología , Proteínas de Transporte de Monosacáridos/metabolismo , Contracción Muscular/fisiología , Proteínas Musculares , Músculos/metabolismo , Animales , Autorradiografía , Radioisótopos de Carbono , Membrana Celular/metabolismo , Proteínas de Unión al GTP/aislamiento & purificación , Transportador de Glucosa de Tipo 4 , Miembro Posterior , Manitol/metabolismo , Proteínas de Transporte de Monosacáridos/aislamiento & purificación , Músculos/efectos de los fármacos , Músculos/fisiología , Perfusión , Radioisótopos de Fósforo , Ratas , Ratas Zucker , Nervio Ciático/fisiología , Tritio
13.
Biochem Biophys Res Commun ; 193(3): 809-13, 1993 Jun 30.
Artículo en Inglés | MEDLINE | ID: mdl-8323556

RESUMEN

The ARF class of low molecular mass GTP-binding proteins, originally detected as cholera toxin-activated ADP-ribosylation factors (ARF) in mammalian cells, is now known to participate in intracellular membrane vesicle trafficking. We identified a GTP-binding protein in pea plumules which resembles ARF in several respects. Like mammalian ARF, the pea protein had an apparent molecular mass of 21 kDa and was distributed mainly (approximately 97%) in the cytosol, with 1% and 1.5% occurring in the Golgi and microsomal fractions, respectively. In comparison, small GTP-binding proteins in the 26-30 kDa range were enriched in membranous fractions. The 21 kDa protein crossreacted strongly with an ARF class I antibody prepared against a mammalian ARF, but did not crossreact with ARF 5 (of class II) antibodies. An anti-Volvox yptl antibody did not show immunoreactivity to the 21 kDa pea protein, although it crossreacted strongly with a 28 kDa pea plumule protein. Our results strongly suggest that the 21 kDa pea protein is an analog of the ARF protein localized in the cytosol of mammalian cells. As far as we are aware, this is the first observation of an ARF protein in plants.


Asunto(s)
Fabaceae/metabolismo , Proteínas de Unión al GTP/aislamiento & purificación , Proteínas de Unión al GTP/metabolismo , Guanosina Trifosfato/metabolismo , Plantas Medicinales , Factores de Ribosilacion-ADP , Autorradiografía , Western Blotting , Proteínas Portadoras/aislamiento & purificación , Proteínas Portadoras/metabolismo , Electroforesis en Gel de Poliacrilamida , Fabaceae/química , Peso Molecular , Radioisótopos de Fósforo
14.
Plant J ; 4(2): 399-402, 1993.
Artículo en Inglés | MEDLINE | ID: mdl-11542500

RESUMEN

Three GTP-binding proteins with apparent molecular masses of 27, 28 and 30 kDa have been detected in isolated nuclei of etiolated pea plumules. After LDS-PAGE and transfer to nitrocellulose these proteins bind [32P]GTP in the presence of excess ATP, suggesting that they are monomeric G proteins. When nuclei are disrupted, three proteins co-purify with the nuclear envelope fraction and are highly enriched in this fraction. The level of [32P]GTP-binding for all three protein bands is significantly increased when harvested pea plumules are irradiated by red light, and this effect is reversed by far-red light. The results indicate that GTP-binding activity associated with the nuclear envelope of plant cells is photoreversibly regulated by the pigment phytochrome.


Asunto(s)
Núcleo Celular/metabolismo , Proteínas de Unión al GTP/metabolismo , Proteínas de Unión al GTP/fisiología , Fitocromo/metabolismo , Luz , Pisum sativum/citología , Pisum sativum/metabolismo , Radioisótopos de Fósforo , Transducción de Señal/fisiología
15.
Pak J Pharm Sci ; 5(2): 147-54, 1992 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-16414714

RESUMEN

In order to judge the therapeutic efficacy of thiamine (vitamin B(1)) in B-complex preparations, three commercial syrup preparations were analysed for thiamine content and their blood absorption in rabbits was compared with that of thiamine as a single entity. A separate experiment was performed to find the effect of sugar concentration on the blood absorption of thiamine. The difference in the quantitative values of vitamin B(1) absorbed in the single and compound preparations under the same conditions has been assumed as one of the criteria to ascertain the therapeutic efficiency of both the forms.

16.
J Biol Chem ; 265(25): 14817-21, 1990 Sep 05.
Artículo en Inglés | MEDLINE | ID: mdl-2168392

RESUMEN

Irradiation of sunflower (Helianthus annuus L. cv. Russian Mammoth) hypocotyls with white light resulted in a 51% decrease in plasma membrane phosphatidylinositol monophosphate (PIP) kinase activity. As little as 10 s of white light irradiation was sufficient to lower the phosphatidylinositol bisphosphate (PIP2) produced in the in vitro phosphorylation assay. This decrease was not caused by an increase in phospholipase C activity since analysis of the water-soluble products indicated no increase in inositol bisphosphate or inositol trisphosphate. Treatment of the plasma membrane with 200 microM vanadate prior to phosphorylation enhanced the PIP kinase and appeared to overcome the light inhibition. In addition to decreasing the PIP kinase activity, light irradiation resulted in a corresponding decrease in the H(+)-ATPase activity to 53% of the dark control values. The plasma membrane ATPase activity increased approximately 2-fold when PIP or PIP2 was added to the isolated membranes. Thus, effects of external stimuli on the level of plasma membrane PIP or PIP2 could affect plasma membrane ATPase activity directly and thereby provide an alternative mechanism for control of cell growth.


Asunto(s)
Luz , Fosfotransferasas/metabolismo , Plantas/enzimología , ATPasas de Translocación de Protón/metabolismo , 1-Fosfatidilinositol 4-Quinasa , Membrana Celular/enzimología , Oscuridad , Fosfatos de Inositol/farmacología , Cinética , Lípidos de la Membrana/aislamiento & purificación , Lípidos de la Membrana/metabolismo , Fosfatidilinositoles/farmacología , Fosfolípidos/aislamiento & purificación , Fosfolípidos/metabolismo , Fosfotransferasas/efectos de la radiación , ATPasas de Translocación de Protón/efectos de la radiación , Vanadatos/farmacología
17.
Plant Physiol ; 91(2): 477-80, 1989 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-16667056

RESUMEN

The metabolism of exogenously added d-myo-[1-(3)H]inositol 1,4,5-trisphosphate (IP(3)) has been examined in microsomal membrane and soluble fractions of carrot (Daucus carota L.) cells grown in suspension culture. When [(3)H]IP(3) was added to a microsomal membrane fraction, [(3)H]IP(2) was the primary metabolite consisting of approximately 83% of the total recovered [(3)H] by paper electrophoresis. [(3)H]IP was only 6% of the [(3)H] recovered, and 10% of the [(3)H]IP(3) was not further metabolized. In contrast, when [(3)H]IP(3) was added to the soluble fraction, approximately equal amounts of [(3)H]IP(2) and [(3)H]IP were recovered. Ca(2+) (100 micromolar) tended to enhance IP(3) dephosphorylation but inhibited the IP(2) dephosphorylation in the soluble fraction by about 20%. MoO(4) (2-) (1 millimolar) inhibited the dephosphorylation of IP(3) by the microsomal fraction and the dephosphorylation of IP(2) by the soluble fraction. MoO(4) (2-), however, did not inhibit the dephosphorylation of IP(3) by the soluble fraction. Li(+) (10 and 50 millimolar) had no effect on IP(3) metabolism in either the soluble or membrane fraction; however, Li(+) (50 millimolar) inhibited IP(2) dephosphorylation in the soluble fraction about 25%.

18.
Biochem Biophys Res Commun ; 162(3): 1295-301, 1989 Aug 15.
Artículo en Inglés | MEDLINE | ID: mdl-2548494

RESUMEN

Phosphatidylinositol-4-monophosphate and phosphatidylinositol-4,5-bisphosphate increased the activity of the vanadate-sensitive ATPase associated with plasma membranes isolated from both sunflower hypocotyls and carrot suspension culture cells. The response was not due to the metabolism of the polyphosphoinositides since diacylglycerol, inositol-1,4-bisphosphate, inositol-1,4,5-trisphosphate, glycerophosphoinositol monophosphate and glycerophosphoinositol bisphosphate had no effect. These data suggest that activation of the inositol phospholipid kinases could be a critical step in signal transduction in plants.


Asunto(s)
Adenosina Trifosfatasas/metabolismo , Fosfatidilinositoles/farmacología , Plantas/enzimología , 1-Fosfatidilinositol 4-Quinasa , Membrana Celular/enzimología , Activación Enzimática/efectos de los fármacos , Fosfatos de Inositol/farmacología , Fosfotransferasas/metabolismo
19.
Plant Physiol ; 74(3): 730-4, 1984 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-16663490

RESUMEN

Influx and accumulation of K(+) in barley (Hordeum vulgare L. cv Fergus) roots were measured at two temperatures (10 degrees C and 20 degrees C) in plants which had been grown with roots and shoots at 20 degrees C (HT plants), with roots and shoots at 10 degrees C (LT plants), and with roots at 10 degrees C and shoots at 20 degrees C (DT plants). Under conditions where K(+) was in limited supply during the prior growth period, K(+) influx and accumulation were consistently higher in roots of DT and LT plants than in those of HT plants. Thus, it would appear that this low temperature response is not limited specifically to conditions in which temperature differentials are maintained between roots and shoots. Nevertheless, it was generally the case that increases of influx were larger in DT and LT plants so that the temperature differentials may intensify the low temperature response. When K(+) influx was examined over a wide range of root [K(+)], it was seen that the characteristic reduction of influx associated with increased internal [K(+)] was substantially greater in HT than DT or LT plants. Transfer of plants grown under HT conditions to DT or LT regimes led to both short-term and long-term adjustments of influx. The former became apparent within 6 hours of exposure to the new conditions and decayed within minutes of transfer back to 20 degrees C. The long-term adjustments were only apparent after prolonged exposure (days) to the lower root temperature and these did not decay as rapidly. Regardless of shoot temperature, the transfer of roots from 20 degrees C to 10 degrees C caused a gradual increase of root [K(+)] so that 4 days later LT and DT roots contained, respectively, 53.3 and 49.83 micromoles per gram compared to 17.82 micromoles per gram for roots maintained at 20 degrees C.

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