Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 92
Filtrar
Más filtros

Intervalo de año de publicación
1.
Microb Ecol ; 84(3): 821-833, 2022 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-34671827

RESUMEN

The worldwide production of vanilla, a native orchid from Mexico, is greatly affected by stem and root rot disease (SRD), typically associated with Fusarium oxysporum fungi. We hypothesized that the presence of Fusarium species in vanilla is not sufficient for the plant to express symptoms of the disease. We described the taxonomic composition of endophytic microbiomes in symptomatic and asymptomatic vanilla plants using 16S and ITS rDNA metabarcoding, and ITS Sanger sequences generated from fungal isolates. We compared the bacterial and fungal diversity in vanilla plants from a long-term plantation, and from feral plants found near abandoned plantations that did not present SRD symptoms. No significant differences were found in the species richness of the bacterial and fungal microbiome among feral, or asymptomatic and symptomatic cultivated vanilla. However, significant differences were detected in both fungal and bacterial diversity from different organs in the same plant, with roots being more diverse than stems. We found that Proteobacteria and Actinobacteria, as well as the fungal families Nectriaceae and Xylariaceae, constitute the core of the vanilla microbiome that inhabits the root and stem of both cultivated and feral plants. Our work provides information on the microbial diversity associated to root and stem rot in vanilla and lays the groundwork for a better understanding of the role of the microbiome in vanilla fungal diseases.


Asunto(s)
Microbiota , Vanilla , Humanos , Vanilla/microbiología , ADN Ribosómico , Bacterias/genética , México
2.
J Clin Rheumatol ; 27(6S): S153-S160, 2021 Sep 01.
Artículo en Inglés | MEDLINE | ID: mdl-32897991

RESUMEN

BACKGROUND: Rheumatoid arthritis (RA) is a chronic autoimmune disease that leads to joint deformity and disability, as well as muscle involvement. Sarcopenia is characterized by a progressive age-related loss of muscle mass and strength. AIM: The aim of this study was to evaluate the prevalence of sarcopenia and possible contributing factors associated with sarcopenia in RA patients. PATIENTS AND METHODS: Adult RA patients (n = 105) of both sexes and 100 subjects as control group (CG) matched by age, sex, and body mass index were included in this cross-sectional study. Whole-body composition was measured by dual-energy x-ray absorptiometry. Sarcopenia was defined according to European Working Group on Sarcopenia in Older People 2 as low muscle strength (handgrip) and low muscle mass (appendicular skeletal muscle mass [ASM] index by dual-energy x-ray absorptiometry). The association between sarcopenia and associated factors was evaluated using logistic regression analyses. RESULTS: Significantly lower percentage of lean mass and ASM were found in the whole RA group compared with controls. However, lower lean parameters (total lean mass, percentage of lean mass, and ASM) were observed only in female subjects. The ASM index was significantly lower in female subjects with RA (RA 31.0% vs CG 11.9%) without differences in male subjects. On the other hand, fat mass and most adipose indices were significantly higher in both female and male subjects with RA. Female RA patients had higher prevalence of sarcopenia and sarcopenic obesity. Through univariate logistic regression analysis, the time of corticosteroids use, cumulative corticosteroid dose, previous fragility fractures, total lean mass, and ASM were associated with sarcopenia. CONCLUSIONS: Higher prevalence of sarcopenia and sarcopenic obesity were found in female RA patients. Sarcopenia was found in younger female subjects with RA compared with healthy control subjects. Sarcopenia was associated with previous fragility fractures in female patients with RA.


Asunto(s)
Artritis Reumatoide , Sarcopenia , Absorciometría de Fotón , Adulto , Anciano , Artritis Reumatoide/complicaciones , Artritis Reumatoide/diagnóstico , Artritis Reumatoide/epidemiología , Composición Corporal , Índice de Masa Corporal , Estudios Transversales , Femenino , Fuerza de la Mano , Humanos , Masculino , Músculo Esquelético , Prevalencia , Sarcopenia/diagnóstico , Sarcopenia/epidemiología , Sarcopenia/etiología
3.
Transpl Infect Dis ; 19(6)2017 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-28941300

RESUMEN

BACKGROUND: Chagas disease (CD) is an endemic zoonosis that occurs in Latin America and is caused by the parasite Trypanosoma cruzi. Early detection of T. cruzi in liver transplant recipients at risk may avoid complications from CD. The aim of this study was to examine the pre-operative evaluation and follow-up of CD after liver transplantation (LT) of patients at risk of CD using real-time quantitative polymerase chain reaction (qPCR) for T. cruzi. METHODS: Between January 2009 and June 2016, 13 (12.7%) of 102 LTs performed in recipients at risk for CD without specific postoperative prophylaxis were prospectively evaluated using qPCR for T. cruzi. Four seronegative patients received livers from seropositive donors (R-/D+) and 9 seropositive recipients received livers from seronegative donors (R+/D-). A cohort of 89 patients without risk for CD during the same time period was analyzed as controls. RESULTS: A positive qPCR for T. cruzi prior to LT was found in 2/9 (22.2%) seropositive recipients, and both achieved early response after therapy. The cumulative incidence of positive parasitemia after LT was higher in R+/D- than R-/D+ (37.7% vs 0%, P = .17). R+/D- transplant patients with positive qPCR achieved therapeutic response without manifestations of acute CD. LT outcomes at 1 year were similar in patients at risk of CD and in controls not at risk for CD. CONCLUSION: A small proportion of T. cruzi-seropositive candidates presented positive parasitemia before LT. After LT, qPCR allowed detection of parasitemia leading to use of preemptive therapy in all R+/D- with T. cruzi replication. No cases of T. cruzi parasitemia occurred in R-/D+.


Asunto(s)
Enfermedad de Chagas/diagnóstico , ADN Protozoario/aislamiento & purificación , Enfermedad Hepática en Estado Terminal/cirugía , Trasplante de Hígado/efectos adversos , Parasitemia/diagnóstico , Trypanosoma cruzi/aislamiento & purificación , Adulto , Anciano , Argentina/epidemiología , Enfermedad de Chagas/tratamiento farmacológico , Enfermedad de Chagas/epidemiología , Enfermedad de Chagas/parasitología , Enfermedad Hepática en Estado Terminal/sangre , Enfermedad Hepática en Estado Terminal/parasitología , Femenino , Estudios de Seguimiento , Humanos , Incidencia , Masculino , Persona de Mediana Edad , Parasitemia/tratamiento farmacológico , Parasitemia/epidemiología , Parasitemia/parasitología , Cuidados Preoperatorios/métodos , Estudios Prospectivos , Reacción en Cadena en Tiempo Real de la Polimerasa , Pruebas Serológicas , Donantes de Tejidos/estadística & datos numéricos , Receptores de Trasplantes/estadística & datos numéricos , Tripanocidas/uso terapéutico , Trypanosoma cruzi/genética , Adulto Joven
4.
Medicina (B Aires) ; 77(1): 46-60, 2017.
Artículo en Español | MEDLINE | ID: mdl-28140312

RESUMEN

Osteoporosis is an evolving disease which affects over 200 million people worldwide. Our recommendations are guidelines for its diagnosis, prevention and treatment, but they do not constitute standards for clinical decisions in individual cases. The physician must adapt them to individual special situations, incorporating personal factors that transcend the limits of these guidelines and are dependent on the knowledge and art of the practice of Medicine. These guidelines should be reviewed and updated periodically as new, better and more effective diagnostic and therapeutic tools become available.


Asunto(s)
Fracturas Óseas/etiología , Osteoporosis , Argentina , Conservadores de la Densidad Ósea/uso terapéutico , Fracturas Óseas/prevención & control , Humanos , Osteoporosis/diagnóstico , Osteoporosis/tratamiento farmacológico , Osteoporosis/prevención & control , Factores de Riesgo
5.
Phys Rev Lett ; 116(17): 171301, 2016 Apr 29.
Artículo en Inglés | MEDLINE | ID: mdl-27176512

RESUMEN

Sound waves from the primordial fluctuations of the Universe imprinted in the large-scale structure, called baryon acoustic oscillations (BAOs), can be used as standard rulers to measure the scale of the Universe. These oscillations have already been detected in the distribution of galaxies. Here we propose to measure BAOs from the troughs (minima) of the density field. Based on two sets of accurate mock halo catalogues with and without BAOs in the seed initial conditions, we demonstrate that the BAO signal cannot be obtained from the clustering of classical disjoint voids, but it is clearly detected from overlapping voids. The latter represent an estimate of all troughs of the density field. We compute them from the empty circumsphere centers constrained by tetrahedra of galaxies using Delaunay triangulation. Our theoretical models based on an unprecedented large set of detailed simulated void catalogues are remarkably well confirmed by observational data. We use the largest recently publicly available sample of luminous red galaxies from SDSS-III BOSS DR11 to unveil for the first time a >3σ BAO detection from voids in observations. Since voids are nearly isotropically expanding regions, their centers represent the most quiet places in the Universe, keeping in mind the cosmos origin and providing a new promising window in the analysis of the cosmological large-scale structure from galaxy surveys.

7.
Clin Cases Miner Bone Metab ; 13(3): 244-246, 2016.
Artículo en Inglés | MEDLINE | ID: mdl-28228791

RESUMEN

Case 1. A 35-year-old woman in the 8th month of her first pregnancy suffered acute lumbar pain that persisted for 4 months. In the 5th month postpartum an acute increase in the low back pain led to a MRI which showed recent deformity in L1 and deformities of undetermined time of evolution in L2, L4, and L5. Laboratory evaluation did not reveal metabolic derangements. She had low bone mineral density (BMD, DXA) and severe deterioration of the microarchitecture of distal appendicular bone (HR-pQCT). Kyphoplasty of all 4 vertebrae was performed in 2 stages, and treatment with subcutaneous denosumab, 60 mg every 6 months, was begun. There was rapid and almost complete improvement in pain. An increase in trabecular bone was documented with HR-pQCT. Case 2. A 33-year-old mother who was breastfeeding her first-born child experimented acute dorsal pain. RMI revealed partial compression fractures in vertebrae D5-7. Her axial BMD was low. There was no family history of osteoporosis, and causes of secondary osteoporosis were ruled out. Her pain slowly subsided with conservative measures, oral analgesics, and nasal calcitonin. Then, treatment with oral strontium ranelate was prescribed; after 3 months serum alkaline phosphatase and osteocalcin had not increased, and after one year lumbar bone mineral density (BMD) was unchanged. Treatment was switched to subcutaneous denosumab. After one year, lumbar BMD had increased 14%, and the pain had almost completely subsided.

8.
Rheumatol Int ; 35(3): 499-505, 2015 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-24980067

RESUMEN

Rheumatoid arthritis (RA) is a chronic systemic inflammatory autoimmune disease with high prevalence of osteoporosis. Previous evidence indicates an association between vitamin D deficiency and autoimmune diseases. The aim of this study was to evaluate serum 25 hydroxyvitamin D [25(OH)D] levels, bone mineral density (BMD) and disease activity in RA patients living in Argentina. We studied 34 RA women and 41 healthy women as a control group. RA patients had lower 25(OH)D levels (20.4 ± 0.9 ng/ml) than controls (26.3 ± 1.9 ng/ml; p < 0.05). No significant differences were found in lumbar spine BMD between premenopausal (preM) or postmenopausal (postM) patients, but femoral neck BMD was significantly lower in postM RA patients (T score -2.5 ± 0.4) than in postM control subjects (T score -0.9 ± 0.3, p = 0.014). Although no linear correlation between 25(OH)D levels and disease activity (DAS-28) was found, patients with moderate-high disease activity had lower 25(OH)D levels than those with low disease activity: DAS-28 >3.2: 19.5 ± 0.88 ng/ml; DAS-28 ≤3.2: 23.7 ± 2.8 ng/ml (p = 0.047). After 1 year of vitamin D treatment 25(OH)D levels were increased while DAS-28 were decreased (n = 25; p < 0.05). We conclude that patients with RA had lower 25(OH)D levels than the control group. Low levels of 25(OH)D were associated with moderate-high disease activity suggesting the importance of optimal 25(OH)D levels in RA patients. Femoral neck BMD was lower in postM RA patients. No differences in lumbar BMD were found between preM and postM RA patients, suggesting that bone mass evaluation in RA patients should include femoral neck BMD regardless of age.


Asunto(s)
Artritis Reumatoide/fisiopatología , Cuello Femoral/diagnóstico por imagen , Vértebras Lumbares/diagnóstico por imagen , Deficiencia de Vitamina D/sangre , Vitamina D/análogos & derivados , Absorciometría de Fotón , Adulto , Anciano , Antirreumáticos/uso terapéutico , Argentina , Artritis Reumatoide/complicaciones , Artritis Reumatoide/tratamiento farmacológico , Densidad Ósea , Femenino , Humanos , Persona de Mediana Edad , Posmenopausia , Premenopausia , Índice de Severidad de la Enfermedad , Resultado del Tratamiento , Vitamina D/sangre , Vitamina D/uso terapéutico , Deficiencia de Vitamina D/complicaciones , Deficiencia de Vitamina D/diagnóstico por imagen , Deficiencia de Vitamina D/tratamiento farmacológico , Adulto Joven
9.
J Inorg Biochem ; 252: 112482, 2024 03.
Artículo en Inglés | MEDLINE | ID: mdl-38218138

RESUMEN

Bacteria utilize heme proteins, such as globin coupled sensors (GCSs), to sense and respond to oxygen levels. GCSs are predicted in almost 2000 bacterial species and consist of a globin domain linked by a central domain to a variety of output domains, including diguanylate cyclase domains that synthesize c-di-GMP, a major regulator of biofilm formation. To investigate the effects of middle domain length and heme edge residues on GCS diguanylate cyclase activity and cellular function, a putative diguanylate cyclase-containing GCS from Shewanella sp. ANA-3 (SA3GCS) was characterized. Binding of O2 to the heme resulted in activation of diguanylate cyclase activity, while NO and CO binding had minimal effects on catalysis, demonstrating that SA3GCS exhibits greater ligand selectivity for cyclase activation than many other diguanylate cyclase-containing GCSs. Small angle X-ray scattering analysis of dimeric SA3GCS identified movement of the cyclase domains away from each other, while maintaining the globin dimer interface, as a potential mechanism for regulating cyclase activity. Comparison of the Shewanella ANA-3 wild type and SA3GCS deletion (ΔSA3GCS) strains identified changes in biofilm formation, demonstrating that SA3GCS diguanylate cyclase activity modulates Shewanella phenotypes.


Asunto(s)
GMP Cíclico/análogos & derivados , Proteínas de Escherichia coli , Shewanella , Globinas/química , Oxígeno/metabolismo , Proteínas de Escherichia coli/química , Liasas de Fósforo-Oxígeno/química , Biopelículas , Hemo/química , Proteínas Bacterianas/química
10.
Medicina (B Aires) ; 73(1): 43-6, 2013.
Artículo en Español | MEDLINE | ID: mdl-23335706

RESUMEN

A case of oncogenic osteomalacia in a 50-year-old male is here presented. He suffered severe bone pain and marked muscular weakness of 4 years' duration. There were several vertebral deformities in the thoracic spine, bilateral fractures of the iliopubic branches, another fracture in the left ischiopubic branch, and a Looser's zone in the right proximal tibia. An octreotide-Tc scan allowed to identify a small tumor in the posterior aspect of the right knee. It was surgically removed. Microscopically, it was a phosphaturic mesenchymal tumor-mixed connective tissue (PMT-MCT). Expression of FGF-23 was documented by immune-peroxidase staining. There was rapid improvement, with consolidation of the pelvic fractures and the tibial pseudo-fracture. The laboratory values returned to normal.


Asunto(s)
Factores de Crecimiento de Fibroblastos/metabolismo , Mesenquimoma/metabolismo , Neoplasias de Tejido Conjuntivo/etiología , Factor-23 de Crecimiento de Fibroblastos , Humanos , Hipofosfatemia Familiar/etiología , Rodilla , Masculino , Persona de Mediana Edad , Osteomalacia , Síndromes Paraneoplásicos
11.
Medicina (B Aires) ; 73(1): 55-74, 2013.
Artículo en Español | MEDLINE | ID: mdl-23335710

RESUMEN

Osteoporosis is a constantly growing disease which affects over 200 million people worldwide. The present recommendations are guidelines for its diagnosis, prevention and treatment, but they do not constitute standards for clinical decisions in individual patients. The physician must adapt them to individual patients and special situations, incorporating personal factors that transcend the limits of these guidelines and are dependent on the knowledge and art of the physician. These guidelines should be reviewed and updated periodically as new, better and more effective diagnostic and therapeutic tools become available.


Asunto(s)
Osteoporosis/diagnóstico , Osteoporosis/terapia , Argentina , Conservadores de la Densidad Ósea/uso terapéutico , Fracturas Óseas/prevención & control , Humanos , Osteoporosis/prevención & control , Factores de Riesgo , Vitamina D/administración & dosificación
12.
Int J Endocrinol ; 2023: 9355672, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-36686321

RESUMEN

Purpose: To evaluate the effect of teriparatide (TPTD) on bone mineral density (BMD) and bone markers under clinical practice conditions. To assess whether the results in real-life match those published in clinical trials. Methods: Cross-sectional study of postmenopausal women treated with TPTD for at least 12 months. Results: 264 patients were included in the study. Main characteristics are as follows: age: 68.7 ± 10.2 years, previous fractures: 57.6%, and previously treated with antiresorptive (AR-prior): 79%. All bone turnover markers studied significantly increased after 6 months. CTX and BGP remained high up to 24 months, but total and bone alkaline phosphatase returned to basal values at month 18. There was a significant increase in lumbar spine (LS) BMD after 6 months (+6.2%), with a maximum peak at 24 months (+13%). Femoral neck (FN) and total hip (TH) BMD showed a significant increase later than LS (just at month 12), reaching a maximum peak at month 24 (FN + 7.9% and TH + 5.5%). A significant increase in LS BMD was found from month 6 to month 24 compared to basal in both AR-naïve, and AR-prior patients (+16.7% and +10.5%, respectively), without significant differences between the two groups. Comparable results were found in FN and TH BMD. Main conclusions. As reported in real-life clinical studies, treatment of osteoporotic postmenopausal women with TPTD induced a significant increase in bone turnover markers from month 6 onward and an increase in BMD from months 6-12 with continuous gain up to month 24. The real-life results of our study matched the results of randomized clinical trials. In addition, TPTD induced an increase in BMD, regardless of the previous use of AR.

14.
Rev Fac Cien Med Univ Nac Cordoba ; 79(3): 235-240, 2022 09 16.
Artículo en Inglés | MEDLINE | ID: mdl-36149074

RESUMEN

Introduction: Several studies reported than vitamin D deficiency increases the risk of macrovascular and microvascular disease in patients with type 2 diabetes (T2DM). We investigated the plasma levels of 25OHD in adult patients T2DM, risk factors for 25OHD deficiency and the relationship between 25OHD, glycemic control and chronic complications of T2DM. Methods: A cross-sectional study was carried out, in which 25OHD levels were evaluated in adult patients (over 18 years) with T2DM. Correlation analyses were performed to evaluate the interdependence of the 25OHD with other continuous variables. A receiver operating characteristic analysis was also performed to identify cutoff values for diagnosing vitamin D deficiency. Logistic regression was performed to identify the independent association between vitamin D deficiency and the variables associated with lower 25OHD. Results: 208 patients were analyzed. The mean age of the patients was 62 years.  The 25OHD level was 19 ng/ml (IQR 13.28-24.43), 59.78% had vitamin D deficiency, and 10.33% had severe deficiency. Glycemia, HbA1c, and BMI were negatively correlated with 25OHD. Cutoff point for vitamin D deficiency was 33.39 kg/m2 for body mass index (BMI), 123 mg/dl for glycemia, and 6.65% for HbA1c. In multivariate logistic regression, BMI>33.39 kg/m2, glycemia >123.5 mg/dl, and albuminuria presented higher odds of vitamin D deficiency. Conclusion: Vitamin D deficiency was highly prevalent among patients with T2DM. Low levels were related to higher fasting plasma glucose, higher BMI, and diabetic nephropathy.


Introducción: Varios estudios reportaron que la deficiencia de vitamina D aumenta el riesgo de enfermedad macrovascular y microvascular en pacientes con diabetes tipo 2 (DM2). Investigamos los niveles de 25OHD en adultos con DM2, factores de riesgo de deficiencia de 25OHD y relación entre 25OHD, control glucémico y complicaciones crónicas de la DM2. Métodos: Se realizó un estudio transversal en el que se evaluaron los niveles de 25OHD en adultos (mayores de 18 años) con DM2. Se realizaron análisis de correlación para evaluar la interdependencia de la 25OHD con otras variables continuas. Se realizó un análisis de las características operativas del receptor para identificar valores de corte para diagnóstico de deficiencia de vitamina D. Se realizó una regresión logística para identificar asociación independiente entre deficiencia de 25OHD y variables asociadas con una menor 25OHD. Resultados: Se analizaron 208 pacientes. La edad media fue 62 años. El nivel de 25OHD fue 19 ng/ml (IQR 13.28-24.43), 59.78% tenía deficiencia de vitamina D y 10.33% tenía deficiencia severa. Glucemia, HbA1c y IMC correlacionaron negativamente con 25OHD. El punto de corte para deficiencia de vitamina D fue 33,39 kg/m2 para índice de masa corporal (IMC), 123 mg/dl para glucemia y 6,65% para HbA1c. En la regresión logística multivariada, IMC >33,39 kg/m2, glucemia >123,5 mg/dl y albuminuria presentaron mayores probabilidades de deficiencia de vitamina D. Conclusión principal: La deficiencia de vitamina D fue altamente prevalente en los pacientes con DM2. Niveles bajos de 25OHD se relacionaron con mayor glucemia, mayor IMC y nefropatía diabética.


Asunto(s)
Diabetes Mellitus Tipo 2 , Deficiencia de Vitamina D , Adulto , Glucemia/análisis , Estudios Transversales , Diabetes Mellitus Tipo 2/complicaciones , Hemoglobina Glucada/análisis , Control Glucémico , Humanos , Persona de Mediana Edad , Factores de Riesgo , Vitamina D , Deficiencia de Vitamina D/complicaciones , Deficiencia de Vitamina D/diagnóstico
15.
J Inorg Biochem ; 230: 111775, 2022 05.
Artículo en Inglés | MEDLINE | ID: mdl-35247855

RESUMEN

Non-canonical heme oxygenases are enzymes that degrade heme to non-biliverdin products within bacterial heme iron acquisition pathways. These enzymes all contain a conserved second-sphere Trp residue that is essential for enzymatic turnover. Here, UV/Vis absorption (Abs) and circular dichroism (CD) spectroscopies were employed to show that the W67F variant of IsdG perturbs the heme substrate conformation. In general, a dynamic equilibrium between "planar" and "ruffled" substrate conformations exists within non-canonical heme oxygenases, and that the second-sphere Trp favors population of the "ruffled" substrate conformation. 1H nuclear magnetic resonance and magnetic CD spectroscopies were used to characterize the electronic structures of IsdG and IsdI variants with different substrate conformational distributions. These data revealed that the "ruffled" substrate conformation promotes partial porphyrin-to­iron electron transfer, which makes the meso carbons of the porphyrin ring susceptible to radical attack. Finally, UV/Vis Abs spectroscopy was utilized to quantify the enzymatic rates, and electrospray ionization mass spectrometry was used to identify the product distributions, for variants of IsdG with altered substrate conformational distributions. In general, the rate of heme oxygenation by non-canonical heme oxygenases depends upon the population of the "ruffled" substrate conformation. Also, the production of staphylobilin or mycobilin by these enzymes is correlated with the population of the "ruffled" substrate conformation, since variants that favor population of the "planar" substrate conformation yield significant amounts of biliverdin. These data can be understood within the framework of a concerted rearrangement mechanism for the monooxygenation of heme to meso-hydroxyheme by non-canonical heme oxygenases.


Asunto(s)
Hemo , Staphylococcus aureus , Proteínas Bacterianas/química , Catálisis , Hemo/química , Hemo Oxigenasa (Desciclizante)/química , Hierro , Oxigenasas/química , Staphylococcus aureus/metabolismo
16.
Dalton Trans ; 49(4): 1065-1076, 2020 Jan 28.
Artículo en Inglés | MEDLINE | ID: mdl-31868194

RESUMEN

The nickel chelatase CfbA is the smallest member of the chelatase family, but the mechanism by which this enzyme inserts nickel into sirohydrochlorin is unknown. In order to gain mechanistic insight, metal binding, tetrapyrrole binding, and enzyme activity were characterized for a variety of substrates using several spectroscopic and computational approaches. Mass spectrometery and magnetic circular dichroism experiments revealed that CfbA binds an octahedral, high-spin metal substrate. UV/Vis absorption spectroscopy demonstrated that the enzyme binds a wide range of tetrapyrrole substrates and perturbs their electronic structures. Based upon activity assays, CfbA promotes insertion of cobalt and nickel into several tetrapyrroles, including cobalt insertion into protopophyrin IX. Finally, density functional theory models were developed which strongly suggest that observed spectral changes upon binding to the enzyme can be explained by tetrapyrrole ruffling, but not deprotonation or saddling. The observation of an octahedral, high-spin metal bound to CfbA leads to a generalization for all class II chelatases: these enzymes bind labile metal substrates and metal desolvation is not a rate-limiting step. The conclusion that CfbA ruffles its tetrapyrrole substrate reveals that the CfbA mechanism is different from that currently proposed for ferrochelatase, and identifies an intriguing correlation between metal substrate specificity and tetrapyrrole distortion mode in chelatases.


Asunto(s)
Biocatálisis , Liasas/metabolismo , Níquel/metabolismo , Tetrapirroles/metabolismo , Archaeoglobus fulgidus/enzimología , Cobalto/metabolismo , Liasas/química , Modelos Moleculares , Conformación Proteica , Pliegue de Proteína
17.
Medicina (B Aires) ; 69(5): 571-5, 2009.
Artículo en Español | MEDLINE | ID: mdl-19897447

RESUMEN

The efficacy of new pharmacological agents for the prevention of osteoporotic fractures and the clinical decision to intervene with that purpose in daily medical practice have been guided by the evaluation of bone mineral density (BMD). However, given the multifactorial nature of the proposed endpoint, a new calculator has been proposed: Fracture Risk Assessment Tool FRAX, which follows the same objectives of previous models, but integrates and combines several of those factors according to their relative weight. It can estimate absolute risk of hip fracture (or a combination of osteoporotic fractures) for the following 10 years. The calculator could be adapted for use in any country by the incorporation of hip fracture incidence and age- and sex-adjusted life expectancy in the same country. This instrument has been presented as a new paradigm to assist in clinical and therapeutic decision-making. In the present review some of its characteristics are discussed, such as: the purported applicability to different populations, the convenience of using 10-year absolute fracture risk for the whole age range under consideration, and whether the efficacy of pharmacological treatment for the prevention of bone fractures in osteoporotic patients can be expected to be equally effective among patients selected for treatment on the basis of this model. Finally, we would like to call attention to the fact that risk thresholds for intervention are not yet clearly defined; those thresholds can obviously be expected to have a profound impact on the number of patients amenable to treatment.


Asunto(s)
Fracturas Óseas/etiología , Osteoporosis/complicaciones , Medición de Riesgo/métodos , Absorciometría de Fotón , Densidad Ósea , Femenino , Fracturas Óseas/prevención & control , Humanos , Masculino , Valor Predictivo de las Pruebas
18.
Actual. osteol ; 19(2): 144-159, sept. 2023. ilus, tab
Artículo en Español | LILACS, UNISALUD, BINACIS | ID: biblio-1523956

RESUMEN

Osteoporosis and vertebral and non-vertebral fractures are common in glucocorticoids (GC) treated patients. Oral GC treatment leads to bone loss, particularly of trabecular bone. The benefits of GC used in rheumatological and traumatological disorders are known but they would have possible negative effects on bone. This systematic review aimed to evaluate the effects of epidural steroid injections (ESI), and intra-articular and intramuscular GC administration on bone mineral density (BMD) and fragility fractures. A systematic review of Medline/PubMed, Cochrane, and LILACS up to November 2020 was conducted. Meta-analyses, systematic reviews, randomized and non-randomized controlled trials, and prospective and retrospective studies comparing the effect of ESI, intra-articular or intramuscular GC used compared to a control group or baseline measurements were included. Results: A total of 8272 individuals were included among the 13 selected articles (10 about ESI and 3 about intra-articular GC; no article was found evaluating intramuscular GC). Only a few studies showed a negative effect of ESI on bone in the qualitative analysis considering osteopenia and osteoporosis in lumbar spine, femoral neck and total hip and BMD as surrogate outcomes. On the other hand, the qualitative analysis showed that most studies found an increased risk of fragility fracture. However, only two studies could be included in the quantitative analysis, in which there were no differences between patients exposed to ESI versus controls in all evaluated regions. In conclusion, there was insufficient evidence to suggest that ESI and intra-articular GC, unlike oral GC, negatively affect bone mass. Longitudinal studies are needed to obtain more knowledge regarding the effect of ESI or intra-articular GC on BMD and fragility fractures. (AU)


La osteoporosis y las fracturas vertebrales y no vertebrales son comunes en pacientes tratados con glucocorticoides (GC). El tratamiento oral con GC conduce a la pérdida ósea, particularmente del hueso trabecular. Los beneficios de los GC utilizados en patologías reumatológicas y traumatológicas son conocidos, pero tendrían posibles efectos negativos sobre el hueso. Esta revisión sistemática tuvo como objetivo evaluar los efectos de las inyecciones epidurales de esteroides (ESI), GC intraarticulares e intramusculares sobre la densidad mineral ósea (DMO) y las fracturas por fragilidad. Se realizó una revisión sistemática de Medline/PubMed, Cochrane y LILACS hasta noviembre de 2020. Se incluyeron metanálisis, revisiones sistemáticas, ensayos controlados aleatorizados y no aleatorizados, estudios prospectivos y retrospectivos que compararon el efecto de ESI, GC intraarticular o intramuscular utilizado en comparación con un grupo de control o mediciones iniciales. Resultados: Se incluyeron un total de 8272 individuos entre los 13 artículos seleccionados (10 sobre ESI y 3 sobre GC intraarticular; no se encontró ningún artículo que evaluara GC intramuscular). Solo unos pocos estudios mostraron un efecto negativo del ESI sobre el hueso en el análisis cualitativo considerando la osteopenia y la osteoporosis en la columna lumbar, el cuello femoral y la cadera total y la DMO como un resultado indirecto. Por otro lado, el análisis cualitativo mostró que la mayoría de los estudios encontraron un mayor riesgo de fractura por fragilidad. Sin embargo, solo dos estudios pudieron incluirse en el análisis cuantitativo, en los que no hubo diferencias entre los pacientes expuestos a ESI versus los controles en todas las regiones evaluadas. En conclusión, no hallamos datos suficientes para sugerir que la ESI y los GC intraarticulares, a diferencia de los GC orales, afectan negativamente a la pérdida ósea. Se necesitan estudios longitudinales para obtener más conocimiento sobre el efecto de ESI o GC intraarticular en la DMO y las fracturas por fragilidad. (AU)


Asunto(s)
Humanos , Osteoporosis/etiología , Enfermedades Óseas Metabólicas/etiología , Densidad Ósea/efectos de los fármacos , Fracturas Osteoporóticas/inducido químicamente , Glucocorticoides/efectos adversos , Literatura de Revisión como Asunto , Sesgo , Vías de Administración de Medicamentos , Metaanálisis como Asunto , Ensayos Clínicos como Asunto , Medición de Riesgo , Densitometría , Estrógenos/efectos adversos
19.
Medicina (B Aires) ; 67(5): 423-8, 2007.
Artículo en Español | MEDLINE | ID: mdl-18051223

RESUMEN

In this observational, case-control study, 376 inpatients were evaluated in order to determine the association of risk factors (RF) and hip fracture; 151 patients had osteoporotic hip fracture (cases); the remaining were controls. Data were obtained from medical charts, and through a standardized questionnaire about RF. Mean age of the sample (+/- SD) was 80.6 +/- 8.1 years, without statistically significant difference between cases and controls; the female:male ratio was 3:1 in both groups. Fractured women were older than men (82.5 +/- 8.1 vs. 79.7 +/- 7.2 years, respectively; p < 0.01). Physical activity, intake of alcohol and tobacco, and sun exposure were low in all patients. Falls among cases happened predominantly at home (p < 0.001). Among female cases, time spent in household duties was a RF (p = 0.007), which was absent in males. In multivariate analysis, the following RF were significantly more frequent: Cognitive impairment (p = 0.001), and previous falls (p < 0.0001); whereas the following protective factors were significantly different from controls: Calcium intake during youth (p < 0.0001), current calcium intake (p < 0.0001), and mechanical aid for walking (p < 0.0001). Evaluation of RF and protective factors may contribute to diminish the probability of hip fracture, through a modification of personal habits, and measures to prevent falls among elderly adults. Present information can help to develop local and national population-based strategies to diminish the burden of hip fractures for the health system.


Asunto(s)
Accidentes por Caídas/estadística & datos numéricos , Fracturas de Cadera/epidemiología , Osteoporosis/complicaciones , Actividades Cotidianas , Factores de Edad , Anciano , Anciano de 80 o más Años , Consumo de Bebidas Alcohólicas/efectos adversos , Argentina/epidemiología , Densidad Ósea/fisiología , Métodos Epidemiológicos , Femenino , Evaluación Geriátrica , Fracturas de Cadera/etiología , Fracturas de Cadera/prevención & control , Humanos , Masculino , Fumar/efectos adversos
20.
Rev Fac Cien Med Univ Nac Cordoba ; 73(3): 176-180, 2016.
Artículo en Inglés | MEDLINE | ID: mdl-27805554

RESUMEN

BACKGROUND: Parasitic infections by Trypanosoma cruzi (T. cruzi) are frequent in children from endemic areas. Specific therapies have been successfully used in pediatric populations to treat this disease. T. cruzi diagnosis should be optimized and become available for any clinical environment. OBJECTIVE: To study T. cruzi prevalence in children from an area of active transmission and carry out a posttreatment follow-up. To verify the feasibility of detecting DNA of T. cruzi from dried blood spot. METHODS: We analyzed presence of T. cruzi in 78 Aboriginal children (Toba community) that attended to a rural school of Chaco province, Argentina. Serum and whole blood (dried blood spot) were assessed by means of serological techniques and PCR. Positive children received Benznidazole. Diagnosis and post treatment follow-up of T. cruzi infection were performed. RESULTS: The serology assay showed infection in 34 of 78 (43.5%) children studied; PCR was positive in 5/34, displaying parasitemia. Serology remained positive in 28/28 children 120 days post-treatment, while PCR was positive in 18/28 (6/34 children were lost in follow-up). No adverse effects during the treatment were reported. CONCLUSIONS: We were able to establish T. cruzi prevalence in the studied population and also to prove the usefulness of dried blood spot for T. cruzi detection using PCR in isolated areas. This method allowed us to verify early treatment failure. Possible causes of this failure are discussed below.


Asunto(s)
Enfermedad de Chagas/diagnóstico , Trypanosoma cruzi/genética , Adolescente , Argentina/epidemiología , Enfermedad de Chagas/tratamiento farmacológico , Enfermedad de Chagas/epidemiología , Niño , Preescolar , Pruebas con Sangre Seca , Estudios de Factibilidad , Femenino , Humanos , Masculino , Nitroimidazoles/uso terapéutico , Reacción en Cadena de la Polimerasa , Estudios Prospectivos , Población Rural , Sensibilidad y Especificidad , Tripanocidas/uso terapéutico , Trypanosoma cruzi/aislamiento & purificación
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA