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1.
Acta Chir Orthop Traumatol Cech ; 90(6): 400-407, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-38191541

RESUMEN

PURPOSE OF THE STUDY: The aim of arthroscopic Bankart repair is restoration of the anterior block mechanism and regaining stability. There are few studies that have tested the adequacy of the angle made with the glenoid and the height from the glenoid level of the repaired labral tissue, but the correlation with the clinical results is not clear. The aim of this study was to defi ne the correlation of the height and slope of the repaired labral tissue in the glenoid anterior with the clinical results. MATERIAL AND METHODS This prospective study included 20 patients who underwent an arthroscopic Bankart repair. To evaluate the labrum anatomy of the affected shoulder, 4 measurement parameters were defi ned as axial height (Ah), axial slope (As), oblique coronal height (Ch), and oblique coronal slope (Cs) on non-contrast T2 MRI. The measurements were taken preoperatively of the affected shoulder and at 1 year postoperatively of both the affected shoulder and the contralateral asymptomatic shoulder. The measured values were compared with each other and with the contralateral shoulder. Correlations of the anatomic values with the Constant-Murley scores recorded at 1, 3, 6, and 12 months postoperatively were examined with the Wilcoxon test. RESULTS The mean preoperative Constant score of the patients was 57.7 (32-77) and postoperative scores at 1, 3, 6, and 12 months were 63.6 (44-79), 77.8 (61-90), 89.6 (77-100), and 95.2 (79-100), respectively (p=0.001). There was a statistically signifi cant difference in the preoperative MRI measurements of the axial and oblique coronal plane labral height and slope values compared to the postoperative values and those of the asymptomatic contralateral shoulder (p< 0.05 for all). There was no statistically signifi cant difference between the labral height and slope values of both planes postoperatively compared to the asymptomatic contralateral shoulder (p= 0.776, p= 0.910, p= 0.132, p= 0.589, respectively). These increases in the radiological data were not found to be statistically signifi cant in the correlation analysis with the increases in the Constant-Murley scores (Ah p=0.935, As p=0.587, Ch p=0.078, Cs p=0.105). CONCLUSIONS This prospective study was conducted using conventional T2 magnetic resonance imaging, which was suffi cient for the measurement of labral height and slope. This study results showed no signifi cant correlation between the radiological and clinical outcomes. KEY WORDS: Bankart repair, labrum height, labrum slope, functional result.


Asunto(s)
Artroscopía , Hombro , Humanos , Estudios Prospectivos , Escápula , Amputación Quirúrgica
2.
Curr Pharm Des ; 16(6): 619-30, 2010.
Artículo en Inglés | MEDLINE | ID: mdl-20388072

RESUMEN

Changing demographics, including an increase in life expectancy and the growing numbers of elderly has recently focused attention on the need for geriatric dental care. Ageing affects oral tissues in addition to other parts of the human body, and oral health (including oral mucosa, lips, teeth and associated structures, and their functional activity) is an integral component of general health; indeed, oral disease can cause pain, difficulty in speaking, mastication, swallowing, maintaining a balanced diet, not to mention aesthetical considerations and facial alterations leading to anxiety and depression. The World Health Organization recommends the adoption of certain strategies for improving the oral health of the elderly, including the management and maintenance of oral conditions which are necessary for re-establishing effective masticatory function. Oral health is often neglected in the elderly, and oral diseases associated with aging are complex, adversely affecting the quality of life. Although oral health problems are not usually associated with death, oral cancers result in nearly 8,000 deaths each year, and more than half of these occur at an age of 65 years plus. This report, which is dedicated to geriatric physicians, geriatric dentistry and specialists in oral medicine reviews age-related oral changes in elderly patients and efforts to summarize the effects of aging in hard and soft oral tissues.


Asunto(s)
Envejecimiento/patología , Cuidado Dental para Ancianos/métodos , Mucosa Bucal/patología , Salud Bucal , Cuidado Dental para Ancianos/tendencias , Caries Dental/patología , Caries Dental/prevención & control , Humanos , Neoplasias de la Boca/patología , Neoplasias de la Boca/prevención & control , Paladar Duro/patología , Paladar Blando/patología
3.
Int J Clin Pract ; 63(1): 56-62, 2009 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-19125993

RESUMEN

OBJECTIVE: Dyslipidaemia is very common in patients with polycystic ovary syndrome (PCOS) but, beyond plasma lipids, atherogenic lipoprotein (Lp) and apolipoprotein (apo) alterations are still ill defined. DESIGN: We measured concentrations of apoB, Lp(a) and small, dense low-density lipoprotein (LDL) in 42 patients with PCOS [age: 28 +/- 7 years, body mass index (BMI): 27 +/- 5 kg/m(2)] vs. 37 age- and BMI-matched healthy controls. METHODS: Elevated Lp(a) levels considered were those > 30 mg/dl while elevated apoB concentrations were those > 100 g/l. RESULTS: Polycystic ovary syndrome showed increased triglycerides levels (p = 0.0011) and lower high-density lipoprotein (HDL)-cholesterol concentrations (p = 0.0131) while total- and LDL cholesterol were similar. PCOS also showed smaller LDL size (p = 0.0005), higher levels of total small, dense LDL (p < 0.0001), higher concentrations of Lp(a), as considered as absolute values (p = 0.0143) and log-transformed (p = 0.0014), while no differences were found in apoB levels. Elevated Lp(a) concentrations were found in 24% of PCOS, while elevated apoB levels were relatively uncommon (14%). Spearman correlation analysis revealed that Lp(a) concentrations were weakly correlated only with HDL-cholesterol levels (r = -0.378, p = 0.0431). In addition, 36% of patients with PCOS with normal plasma lipid profile showed elevated levels of Lp(a), apoB or small, dense LDL. CONCLUSIONS: Atherogenic Lp abnormalities may be found in one-third of women with PCOS who have a normal lipid pattern. Future prospective studies are needed to test to which extent such atherogenic forms of dyslipidaemia may contribute to the increased cardiovascular risk in young women with PCOS.


Asunto(s)
Apolipoproteínas B/sangre , Enfermedades Cardiovasculares/prevención & control , LDL-Colesterol/sangre , Dislipidemias/sangre , Dislipidemias/complicaciones , Lipoproteína(a)/sangre , Síndrome del Ovario Poliquístico/sangre , Adulto , Índice de Masa Corporal , Estudios de Casos y Controles , Femenino , Humanos , Síndrome del Ovario Poliquístico/complicaciones , Factores de Riesgo , Adulto Joven
4.
Int J Immunopathol Pharmacol ; 22(4): 1077-87, 2009.
Artículo en Inglés | MEDLINE | ID: mdl-20074472

RESUMEN

Eosinophil count in nasal fluid (ECNF) was used to differentiate nasal pathologies. Receiver operating characteristic (ROC) curve analysis and the area under the curve (AUC) were performed to evaluate the ECNF's accuracy in distinguishing allergic rhinitis (AR) from non-allergic rhinitis (NAR). We also evaluated the accuracy of ECNF in recognizing patients with mild and severe symptoms of rhinitis and patients with ineffective and effective clinical responses to antihistamines. 1,170 consecutive adult patients with a clinical history of rhinitis were studied. ECNF's median in AR was 6.0 and 2.0 in NAR and the best cut-off value was > 3.0, AUC = 0.75. ECNF's median in AR with mild nasal symptoms was 3.0 and 7.0 with severe symptoms, and the best cut-off value was 4.0, AUC = 0.90. ECNF's median in NAR with mild nasal symptoms was 2.0 and 8.5 with severe symptoms, and the best cut-off value was > 4.0, AUC = 0.86. ECNF's median in AR with effective clinical response to antihistamines was 4.0 and 8.0 with ineffective response, the best cut-off value was < or = 5.0, AUC = 0.94. ECNF's median in NAR with an effective clinical response to antihistamines was 1.0 and 2.0 with ineffective response, and the best cut-off value was < or = 3.0, AUC = 0.64. Our results suggest an interesting practical use of ECNF data as evaluator of the clinical severity both AR and NAR. As predictor of the clinical response to antihistamines, ECNF is accurate only in patients with AR. The ECNF's performance was moderately accurate in distinguish patients with AR and NAR.


Asunto(s)
Eosinófilos/inmunología , Rinitis Alérgica Perenne/inmunología , Rinitis Alérgica Estacional/inmunología , Rinitis/inmunología , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Área Bajo la Curva , Diagnóstico Diferencial , Femenino , Antagonistas de los Receptores Histamínicos/uso terapéutico , Humanos , Recuento de Leucocitos , Masculino , Persona de Mediana Edad , Líquido del Lavado Nasal/citología , Líquido del Lavado Nasal/inmunología , Selección de Paciente , Valor Predictivo de las Pruebas , Curva ROC , Rinitis/diagnóstico , Rinitis/tratamiento farmacológico , Rinitis Alérgica Perenne/diagnóstico , Rinitis Alérgica Perenne/tratamiento farmacológico , Rinitis Alérgica Estacional/diagnóstico , Rinitis Alérgica Estacional/tratamiento farmacológico , Índice de Severidad de la Enfermedad , Resultado del Tratamiento , Adulto Joven
5.
Curr Med Chem ; 13(16): 1895-902, 2006.
Artículo en Inglés | MEDLINE | ID: mdl-16842200

RESUMEN

Transglutaminases (TGases) are enzymes which catalyze the cross linking of a glutaminyl residue of a protein/peptide substrate to a lysyl residue of a protein/peptide co-substrate with the formation of an N-gamma-(epsilon-L-glutamyl)-L-lysine [GGEL] cross link (isopeptidic bond) and the concomitant release of ammonia. Such cross-linked proteins are often highly insoluble. The TGases are closely related enzymes and can also catalyze other important reactions for cell life. Recently, several findings concerning the relationships between the biochemical activities of the TGases and the basic molecular mechanisms responsible for some human diseases, have been reported. For example, some neurodegenerative diseases, such as Alzheimer's disease (AD), Huntington's disease (HD), Parkinson's disease (PD), supranuclear palsy, etc., are characterized in part by aberrant cerebral TGase activity and by increased cross-linked proteins in affected brains. Our article describes the biochemistry and the physio-pathological roles of the TGase enzymes, with particular reference to human pathologies in which the molecular mechanism of disease can be due to biochemical activities of the tissue TGase enzyme (tTGase, type 2), such as in a very common human disease, Celiac Disease (CD), and also in certain neuropsychiatric disorders.


Asunto(s)
Enfermedad Celíaca/enzimología , Enfermedad Celíaca/patología , Enfermedades Neurodegenerativas/enzimología , Enfermedades Neurodegenerativas/patología , Transglutaminasas/metabolismo , Encéfalo/enzimología , Encéfalo/patología , Catálisis , Humanos , Péptidos/química , Péptidos/metabolismo , Procesamiento Proteico-Postraduccional
6.
J Phys Chem B ; 110(5): 2064-73, 2006 Feb 09.
Artículo en Inglés | MEDLINE | ID: mdl-16471784

RESUMEN

The most extensive data set yet generated correlating photoluminescence excitation (PLE) and photoluminescence (PL) spectra is presented for aged (equilibrated) porous silicon (PS) samples. The observed features, which are temperature independent over the range 10-300 K, show a detailed correlation with the results of photoacoustic spectroscopy (PAS) and with molecular electronic structure calculations. The observed energy level patterns are reproduced in the photoabsorption (PA) of PS films released after the etching of a silicon wafer. It is concluded that the energy level pattern found for the photoluminescing surface of PS results from a structure which is neither uniquely molecule- or bulk-like but represents a hybrid form for which the density of states associated with a polyatomic vibrationally excited surface-bound fluorophor dominates the nature of the observed features which are not those of a semiconductor. These fluorophor features are broadened and shifted to lower excitation energy as a result of the intimate presence of the silicon surface to which the fluorophor is bound. The dominance of the surface-bound fluorophor accounts for the temperature-independent PLE and PL features. The observed spectral features are thus suggested to be the result of a strong synergistic interaction in which the silicon surface influences the location of surface-bound fluorophor excited states whereas the nature of the vibrationally excited surface-bound fluorophor coupling to the silicon surface provides the mechanism for an enhanced vibronic structure dominated interaction and energy transfer. The observed PLE, PL, PAS, and PA measurements are found to be consistent with previous photovoltaic and photoconductivity measurements, correlating well with a surface-bound oxyhydride-like emitter. This study suggests the important role that the overtone structure of a molecule bound to a surface can play as one forms a hybrid system.

7.
Phys Rev Lett ; 95(5): 052003, 2005 Jul 29.
Artículo en Inglés | MEDLINE | ID: mdl-16090867

RESUMEN

A high statistics measurement of the D(s)+ lifetime from the Fermilab fixed-target FOCUS photoproduction experiment is presented. We describe the analysis of the two decay modes, D(s)+ --> phi(1020)pi+ and D(s)+ -->K*(892)0K+, used for the measurement. The measured lifetime is 507.4 +/- 5.5(stat) +/- 5.1(syst) fs using 8961 +/- 105 D(s)+ --> phi(1020)pi+ and 4680 +/- 90 D(s)+ --> K*(892)0K+ decays. This is a significant improvement over the present world average.

8.
Arch Biochem Biophys ; 441(2): 191-8, 2005 Sep 15.
Artículo en Inglés | MEDLINE | ID: mdl-16126157

RESUMEN

The effects of extremely low frequency electromagnetic fields of 75 Hz were studied on different membrane-associated enzymes. Only the activities of three enzymes out of seven exposed to the field decreased approximately of about 54-61% with field amplitudes above a threshold of 73-151 microT depending on the enzyme. The same field had no effect on the activities of either integral membrane enzymes such as Ca,ATPase, Na/K,ATPase, and succinic dehydrogenase or peripheral membrane enzymes such as photoreceptor PDE. The decrease in enzymatic activity of the field-sensitive enzymes was independent of the time of permanence in the field and was completely reversible. When these enzymes were solubilized with Triton, no effect of the field was obtained on the enzymatic activity, suggesting the crucial role of the membrane in determining the conditions for enzyme inactivation. The role of the particular linkage of the field-sensitive enzymes to the membranes is also discussed.


Asunto(s)
Membrana Celular/química , Membrana Celular/efectos de la radiación , Campos Electromagnéticos , Enzimas/química , Enzimas/efectos de la radiación , Proteínas de la Membrana/química , Proteínas de la Membrana/efectos de la radiación , Células Cultivadas , Relación Dosis-Respuesta en la Radiación , Activación Enzimática/efectos de la radiación , Estabilidad de Enzimas/efectos de la radiación , Membrana Eritrocítica/química , Membrana Eritrocítica/efectos de la radiación , Humanos , Dosis de Radiación , Sinaptosomas/química , Sinaptosomas/efectos de la radiación
9.
Bioelectromagnetics ; 25(7): 545-51, 2004 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-15376242

RESUMEN

Extremely low frequency electromagnetic fields (ELF-EMFs) of 75 Hz with amplitudes above a threshold of about 125 microT have a dramatic effect on the adenylate kinase (AK) activity of the rod outer segment (ROS) membranes. In fact, the ATP production by ROS membranes or by purified disk membranes placed in the field decreased by approximately 54%. The decrease in enzymatic activity was independent of the time of exposure to the field and was completely reversible. When disk membranes were solubilized with Triton or a soluble isoform of AK was used, negligible effects of the field were obtained on the enzymatic activity, suggesting that the membrane has an important role in determining the conditions for the enzyme inactivation.


Asunto(s)
Adenilato Quinasa/efectos de la radiación , Campos Electromagnéticos , Segmento Externo de la Célula en Bastón/efectos de la radiación , Adenosina Trifosfato/efectos de la radiación , Adenilato Quinasa/antagonistas & inhibidores , Animales , Bovinos , Membrana Celular/enzimología , Membrana Celular/efectos de la radiación , Isoenzimas/efectos de la radiación , Polietilenglicoles/farmacología , Segmento Externo de la Célula en Bastón/enzimología , Solubilidad , Tensoactivos/farmacología , Factores de Tiempo
10.
Amino Acids ; 26(4): 431-4, 2004 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-15290350

RESUMEN

Transglutaminases are a family of enzymes which show the common capacity to catalyse the cross-linking of protein substrates. Some members of this family of enzymes are also capable to catalyse other chemical reactions for the cell life. The distribution and the role of these enzymes have been studied in numerous cell types and tissues, but only recently their expression and functions started to be investigated in the Nervous System. One of the main biochemical properties of the Transglutaminase enzymes is to form large protein aggregates that are insoluble in all known protein detergents. Recently, the Transglutaminase activity has been hypothesised to be involved in the pathogenetic mechanisms responsible for the formation of cellular inclusions present in the Corea Major and in other polyglutamine diseases. In this review we describe the biochemical mechanisms by which the Transglutaminases could play a critical role in the physiopathology of the polyglutamine diseases.


Asunto(s)
Enfermedades del Sistema Nervioso/enzimología , Péptidos/metabolismo , Transglutaminasas/metabolismo , Animales , Humanos , Cuerpos de Inclusión/química , Cuerpos de Inclusión/metabolismo , Sistema Nervioso/enzimología
11.
Bioelectrochemistry ; 63(1-2): 317-20, 2004 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-15110295

RESUMEN

Adenylate kinase activity in rod outer segment membranes of bovine retina decreased of about 55% when exposed to an extremely low frequency electromagnetic field of 75 Hz and 250 microT. The effect was independent of the time of permanence in the field. Negligible effects of the field were found on the enzymatic activity of a soluble isoform of adenylate kinase or of rod outer segment membranes solubilized with Triton, suggesting the importance of the membrane in determining the conditions of the enzyme inactivation.


Asunto(s)
Adenosina Trifosfato/metabolismo , Adenilato Quinasa/metabolismo , Adenilato Quinasa/efectos de la radiación , Membrana Celular/enzimología , Membrana Celular/efectos de la radiación , Células Fotorreceptoras Retinianas Bastones/enzimología , Células Fotorreceptoras Retinianas Bastones/efectos de la radiación , Adenilato Quinasa/química , Células Cultivadas , Relación Dosis-Respuesta en la Radiación , Electricidad , Campos Electromagnéticos , Activación Enzimática/efectos de la radiación , Dosis de Radiación
12.
Phys Rev Lett ; 88(16): 161801, 2002 Apr 22.
Artículo en Inglés | MEDLINE | ID: mdl-11955226

RESUMEN

A high statistics measurement of the Lambda(+)(c) lifetime from the Fermilab fixed-target FOCUS photoproduction experiment is presented. We describe the analysis technique with particular attention to the determination of the systematic uncertainty. The measured value of 204.6 +/- 3.4 (stat) +/- 2.5 (syst) fs from 8034 +/- 122 Lambda(+)(c)-->pK(-)pi(+) decays represents a significant improvement over the present world average.

13.
J Photochem Photobiol B ; 66(2): 148-52, 2002 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-11897515

RESUMEN

ATP is synthesized on the disk membrane isolated from rod outer segments of the bovine retina. Together with a slow component which accounted for a constant rate of about 22 nmol ATP/min/mg of protein and which was due to the adenylate kinase activity, a fast component with a maximal activity of about 58 nmol ATP/min/mg of protein was measured at physiological calcium concentrations. This fast activity disappeared in the presence of the Ca(2+) ionophore A23187, was inhibited by vanadate or thapsigargin but not by oligomycin, suggesting that this ATP synthesis is due to the reversal functioning of the Ca(2+)-ATPase previously found on the disk membranes.


Asunto(s)
Adenosina Trifosfato/biosíntesis , ATPasas Transportadoras de Calcio/metabolismo , Segmento Externo de la Célula en Bastón/enzimología , Adenosina Difosfato/farmacología , Animales , Calcimicina/farmacología , Calcio/metabolismo , Bovinos , Inhibidores Enzimáticos/farmacología , Ionóforos/farmacología , Segmento Externo de la Célula en Bastón/efectos de los fármacos , Tapsigargina/farmacología
14.
Phys Rev Lett ; 88(4): 041602, 2002 Jan 28.
Artículo en Inglés | MEDLINE | ID: mdl-11801103

RESUMEN

A high-statistics sample of photoproduced charm from the FOCUS experiment has been used to search for direct CP violation in the decay rates for D+-->K(S)pi+ and D+-->K(S)K+. We have measured the following asymmetry parameters relative to D+-->K-pi+pi+: A(CP)(K(S)pi+) = (-1.6+/-1.5+/-0.9)%, A(CP)(K(S)K+) = (+6.9+/-6.0+/-1.5)%, and A(CP)(K(S)K+) = (+7.1+/-6.1+/-1.2)% relative to D+-->K(S)pi+. We have also measured the relative branching ratios and found Gamma(D+-->K(0)pi+)/Gamma(D+-->K-pi+pi+) = (30.60+/-0.46+/-0.32)%, Gamma(D+-->K(0)K+)/Gamma(D+-->K-pi+pi+) = (6.04+/-0.35+/-0.30)%, and Gamma(D+-->K(0)K+)/Gamma(D+-->K(0)pi+) = (19.96+/-1.19+/-0.96)%.

15.
Phys Rev Lett ; 87(16): 162001, 2001 Oct 15.
Artículo en Inglés | MEDLINE | ID: mdl-11690200

RESUMEN

We have studied hadronic four-body decays of D(+) and D(+)(s) mesons with a K(S) in the final state using data recorded during the 1996-1997 fixed-target run of the Fermilab high energy photoproduction experiment FOCUS. We report a new branching ratio measurement of gamma(D(+)-->K(S)K-pi(+)pi(+))/gamma(D(+)-->K(S)pi(+)pi(+)pi(-)) = 0.0768+/-0.0041+/-0.0032. We make the first observation of three new decay modes with branching ratios gamma(D(+)-->K(S)K+pi(+)pi(-))/gamma(D(+)-->K(S)pi(+)pi(+)pi(-)) = 0.0562+/-0.0039+/-0.0040, gamma(D(+)-->K(S)K+K-pi(+))/gamma(D(+)-->K(S)pi(+)pi(+)pi(-)) = 0.0077+/-0.0015+/-0.0009, and gamma(D(+)(s)-->K(S)K+pi(+)pi(-))/gamma(D(+)(s)-->K(S)K-pi(+)pi(+)) = 0.586+/-0.052+/-0.043, where in each case the first error is statistical and the second error is systematic.

16.
Brain Res Bull ; 56(3-4): 169-72, 2001.
Artículo en Inglés | MEDLINE | ID: mdl-11719247

RESUMEN

Transglutaminases (Enzyme Commission 2.3.2.13) are a large family of enzymes that show the common capacity to catalyze cross-linking of protein substrates. Some members of this family of enzymes are also capable of catalyzing other reactions important for the cell life. The distribution and the role of these enzymes have been widely studied in numerous cell types and tissues, but only recently their expression and functions started to be investigated in the central nervous system. One of the main biochemical properties of the transglutaminase enzymes is to form large protein aggregates that are insoluble in all known protein detergents, such as urea, guanidinium, and sodium dodecyl sulfate. Recently, the transglutaminase activity has been hypothesized to be involved in the pathogenetic mechanisms responsible for the formation of cellular inclusions present in Huntington disease and in all the other polyglutamine (polyQ) diseases hitherto identified, such as spinobulbar muscular atrophy or Kennedy disease, spinocerebellar ataxias (SCA-1, SCA-2, SCA-3 or Machado-Joseph disease, SCA-6 and SCA-7) and dentatorubropallidoluysian atrophy. In this review we describe the biochemical properties of the transglutaminase enzymes and some recent findings about the physiopathological roles played by these enzymes in the central nervous system.


Asunto(s)
Atrofia Muscular Espinal/metabolismo , Péptidos/genética , Péptidos/metabolismo , Transglutaminasas/metabolismo , Expansión de Repetición de Trinucleótido , Encéfalo/enzimología , Humanos , Enfermedad de Machado-Joseph/genética , Enfermedad de Machado-Joseph/metabolismo , Atrofia Muscular Espinal/genética
17.
Prog Retin Eye Res ; 20(6): 733-59, 2001 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-11587916

RESUMEN

The present models of phototransduction for vertebrates and invertebrates have been reviewed and the relative literature updated. The emerging picture for vertebrate phototransduction is a result of a better knowledge of its general outlines, although some important details such as the role of calcium ions are still lacking. The molecular events involved in the rising phase of the electrical response have basically been understood, whilst those involved in response inactivation and recovery remain to be elucidated. In an overall strategy, the phototransduction in invertebrates shares a great deal of similarity with that in vertebrates but differs in the underlying molecular events. However, a complete picture of phototransduction in invertebrate photoreceptors has not yet emerged. The available data on the structure of the visual pigment rhodopsin reveal further details on the present model of the retinal-binding pocket of the protein and consequently of the "red shift" of the absorbance of retinal. The problem of the energy supplied during photoreception, in particular, the availability of ATP in the rod outer segment and the presence in the disk membranes of a Ca-ATPase are discussed. Finally, recent progress in understanding the molecular mechanisms of inherited retinal diseases and relative gene identification are summarized.


Asunto(s)
Rodopsina/fisiología , Visión Ocular/fisiología , Animales , Humanos , Células Fotorreceptoras de Invertebrados/fisiología , Células Fotorreceptoras de Vertebrados/fisiología , Enfermedades de la Retina/metabolismo
18.
Phys Rev Lett ; 86(14): 2955-8, 2001 Apr 02.
Artículo en Inglés | MEDLINE | ID: mdl-11290081

RESUMEN

Using a large sample of photoproduced charm mesons from the FOCUS experiment at Fermilab (FNAL-E831), we observe the decay D0-->K+pi- with a signal yield of 149+/-31 events compared to a similarly cut sample consisting of 36 760+/-195 D0-->K-pi+ events. We use the observed ratio of D0-->K+pi- to D0-->K-pi+ (0.404+/-0.085+/-0.025)% to obtain a relationship between the D0 mixing and doubly Cabibbo suppressed decay parameters.

19.
Biochim Biophys Acta ; 1504(2-3): 438-43, 2001 Apr 02.
Artículo en Inglés | MEDLINE | ID: mdl-11245807

RESUMEN

The rod outer segments of bovine retina contain two different adenylate kinases: a soluble activity, which is not sensitive to calcium ion, and an activity bound to disk membranes, which is dependent on the calcium levels. In fact, the maximal activity associated to the disks is reached at Ca(2+) concentrations between 10(-6) and 10(-7) M, which is the range of calcium level actually present in the rod cell. The Michaelis-Menten kinetics of the enzyme activity on disk membranes was determined and the actual concentrations of ATP, AMP and ADP were measured in the photoreceptor outer segment. Therefore, the physiological relevance of the adenylate kinase activity was discussed considering the above results. The formation of ATP catalyzed by the enzyme seems appropriate to supply at least some of the reactions necessary for phototransduction, indicating that ATP could be regenerated from ADP directly on the disk membranes where the photoreception events take place.


Asunto(s)
Adenilil Ciclasas/metabolismo , Retina/enzimología , Segmento Externo de la Célula en Bastón/enzimología , Adenosina Difosfato/metabolismo , Adenosina Trifosfato/metabolismo , Animales , Calcio/metabolismo , Calcio/farmacología , Bovinos , Técnicas In Vitro , Luz , Disco Óptico/enzimología
20.
Biochem Biophys Res Commun ; 268(2): 625-7, 2000 Feb 16.
Artículo en Inglés | MEDLINE | ID: mdl-10679254

RESUMEN

Purified disk membranes from rod outer segments of the bovine retina were able to synthesize ATP with a maximal activity (about 52 nmoles ATP/min/mg of protein) at physiological calcium concentrations. This activity was inhibited by vanadate or thapsigargin but not by oligomycin, suggesting the reversal functioning of the disk Ca(2+)-ATPase, which would act as a ATP synthesizer at the expense of the calcium gradient between the disks and the cytoplasm of the rod outer segment. The results are discussed in terms of the need of an immediate source of ATP on the disk membranes where the energy is required to supply the rapid reactions of the photoreception processes.


Asunto(s)
Adenosina Trifosfato/biosíntesis , ATPasas Transportadoras de Calcio/metabolismo , Calcio/metabolismo , Segmento Externo de la Célula en Bastón/metabolismo , Adenosina Difosfato/metabolismo , Animales , Bovinos , Fosfatos/metabolismo , Células Fotorreceptoras/metabolismo
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