RESUMEN
Evolution of gene regulation is crucial for our understanding of the phenotypic differences between species, populations and individuals. Sequence-specific binding of transcription factors to the regulatory regions on the DNA is a key regulatory mechanism that determines gene expression and hence heritable phenotypic variation. We use a biophysical model for directional selection on gene expression to estimate the rates of gain and loss of transcription factor binding sites (TFBS) in finite populations under both point and insertion/deletion mutations. Our results show that these rates are typically slow for a single TFBS in an isolated DNA region, unless the selection is extremely strong. These rates decrease drastically with increasing TFBS length or increasingly specific protein-DNA interactions, making the evolution of sites longer than â¼ 10 bp unlikely on typical eukaryotic speciation timescales. Similarly, evolution converges to the stationary distribution of binding sequences very slowly, making the equilibrium assumption questionable. The availability of longer regulatory sequences in which multiple binding sites can evolve simultaneously, the presence of "pre-sites" or partially decayed old sites in the initial sequence, and biophysical cooperativity between transcription factors, can all facilitate gain of TFBS and reconcile theoretical calculations with timescales inferred from comparative genomics.
Asunto(s)
Factores de Transcripción/metabolismo , Sitios de UniónRESUMEN
We introduce a one-parametric family of tree growth models, in which branching probabilities decrease with branch age τ as τ(-α). Depending on the exponent α, the scaling of tree depth with tree size n displays a transition between the logarithmic scaling of random trees and an algebraic growth. At the transition (α=1) tree depth grows as (logn)(2). This anomalous scaling is in good agreement with the trend observed in evolution of biological species, thus providing a theoretical support for age-dependent speciation and associating it to the occurrence of a critical point.
Asunto(s)
Modelos Biológicos , Árboles/anatomía & histología , Árboles/fisiología , Bases de Datos Factuales , ProbabilidadRESUMEN
In this study, a total of 17 adult patients ((> or =18 years old; 12 male, 5 female) with encephalitis followed up in neurology and infectious diseases clinics of Trace University Hospital between the years 2000-2005 were retrospectively analyzed. The most common signs and symptoms were confusion (n: 13; 76.4%), nausea and vomiting (n: 13; 76.4%), disorientation (n: 12; 70%), fever and headache (n: 11; 64.7%), amnesia (n: 10; 58.8%), convulsions (n: 9; 52.9%), agitation (n: 7; 41%), dysphasia and aphasia (n: 6; 35.2%), nuchal stiffness (n: 5; 29.4) and focal neurological signs (n: 1; 5.8%). Six of the patients were admitted to the hospital during summer, six during winter, four during spring and one during autumn. Eleven (64.7%) of the patients had electroencephalographic signs compatible with encephalitis. Encephalitis related signs were detected in 83.3% (10/12) of the patients by cranial magnetic resonance imaging and in 58.3% (7/12) by computerized tomography. Cerebrospinal fluid (CSF) examination revealed low glucose levels in 17.6% (3/17), high protein levels in 47% (8/17) and increased white blood cells with a predominance of lymphocytes in 41.2% (7/17) of the cases. CSF findings were within normal limits in 23.5% (4/17) of the patients. Empirical acyclovir treatment was given to all patients. One patient died at the acute phase of the infection while all the other 16 recovered. Since none of the CSF samples yielded bacterial growth, all of the patients were diagnosed as viral encephalitis. However, no investigation was performed to identify the viral etiology and this was the major limitation owing to the inadequacy of laboratory facilities during the study period and/or unawareness of the physicians about viral identification methods.
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Encefalitis Viral/diagnóstico , Adulto , Líquido Cefalorraquídeo/citología , Proteínas del Líquido Cefalorraquídeo/análisis , Diagnóstico Diferencial , Electroencefalografía , Encefalitis Viral/epidemiología , Femenino , Glucosa/líquido cefalorraquídeo , Humanos , Recuento de Leucocitos , Imagen por Resonancia Magnética , Masculino , Estudios Retrospectivos , Tomografía Computarizada por Rayos X , Turquía/epidemiología , Adulto JovenRESUMEN
In 2004 between the months of May-November, 11 patients with spotted fever group (SFG) rickettsioses were admitted to the Trakya University Hospital in Edirne, Turkey. SFG rickettsioses were diagnosed clinically. Before treatment, punch biopsy from skin lesions, especially from the eschar, was performed. Serum specimens were tested by IFA using a panel of nine rickettsial antigens, including SFG rickettsiae and R. typhi. Western blotting and standard PCR were also performed. The average age of the 11 patients (4 male and 7 female) was 51 years. All the patients had high fever; 10 (91%) had maculopapular rash; 8 (73%) had rash in the palms or on the soles. Five patients had a unique eschar; two had double eschars (64%). Two patients presented with multiple organ failure and one of them died. All the patients had significant antibody titers against SFG rickettsiae. PCR experiments of skin biopsies were positive in six (60%) of 10 skin biopsy samples and DNA sequencing of the positive PCR products gave 100% homology with Rickettsia conorii Malish 7 for opmA and gltA. Trakya Region in an endemic area for rickettsioses. In this series, three patients presented with life-threatening diseases and one of them died. This patient was the first fatal case (2.8%). Atypic and serous life-threatening presentations of rickettsioses must be kept in mind for the differential diagnosis of febrile disease in Turkey.
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Fiebre Botonosa/diagnóstico , Infecciones por Rickettsia/diagnóstico , Rickettsia conorii , Fiebre Botonosa/patología , Femenino , Humanos , Masculino , Persona de Mediana Edad , Infecciones por Rickettsia/patología , Piel/patología , TurquíaRESUMEN
The first case of haemorrhagic meningitis due to Bacillus anthracis in the European part of Turkey is reported here. B. anthracis, sensitive to penicillin, was isolated from the cerebrospinal fluid and blood cultures. Although appropriate therapy was administered, the patient died two days after hospitalization.
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Carbunco/complicaciones , Bacillus anthracis , Meningitis Bacterianas/microbiología , Hemorragia Subaracnoidea/microbiología , Adulto , Resultado Fatal , Humanos , MasculinoRESUMEN
BACKGROUND: We carried out this study in order to establish the prevalence of antituberculosis drug resistance in Mycobacterium tuberculosis strains and to determine risk factors for the development of resistance in Trakya region of Turkey. METHODS: Pattern of drug resistance in 214 M. tuberculosis isolates from patients with tuberculosis treated at the regional tuberculosis dispensaries were included in the study. RESULTS: Isolates of 105 (49.1%) were resistant to only one drug, and 62 (29.0%) were resistant to more than one drug. The total resistance rates to streptomycin, isoniazid, rifampicin, ethambutol and isoniazid + rifampicin were 29.0%, 27.1%, 21.5%, 10.3% and 11.6%, respectively. The secondary resistance rates in all drugs and combinations were higher than primary resistance rates (p<0.001). Step wise logistic regression revealed that (i) non-compliance with treatment increases the chances of development of resistance by 15 times [p<0.00001, 95% confidence intervals (95% CI) : 4.16 to 56.70], and (ii) a regimen of inadequate treatment increases the chance of development of drug resistance by 10.5 times (p<0.01, 95% CI=2.66 to 49.80). CONCLUSIONS: We propose that specially trained physicians should institute antituberculosis therapy and medication should be practiced under direct observation in this region.
Asunto(s)
Antituberculosos/farmacología , Farmacorresistencia Bacteriana , Mycobacterium tuberculosis/efectos de los fármacos , Tuberculosis Resistente a Múltiples Medicamentos/microbiología , Tuberculosis Pulmonar/microbiología , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Antituberculosos/uso terapéutico , Niño , Preescolar , Femenino , Humanos , Masculino , Pruebas de Sensibilidad Microbiana , Persona de Mediana Edad , Factores de Riesgo , Tuberculosis Resistente a Múltiples Medicamentos/tratamiento farmacológico , Tuberculosis Resistente a Múltiples Medicamentos/etiología , Tuberculosis Pulmonar/tratamiento farmacológico , Tuberculosis Pulmonar/etiología , TurquíaRESUMEN
In order to find the distinctive features of Salmonellae and Salmonella infections in Turkey, 620 Salmonellae strains, isolated from various clinical samples (481 stool, 108 blood, 12 urine, 3 bone marrow, 3 cerebrospinal fluid, 9 pus, and one from each of the bile, pleural fluid, wound, catheter samples) in 13 clinical microbiology laboratories of 10 provinces in Turkey (Ankara, Antalya, Bursa, Edirne, Eskisehir, Istanbul, Izmir, Kayseri, Konya and Trabzon) between July 1, 2000 and June 30, 2002, were serotyped. Among the patients 43% were female, 57% were male, 63.2% were from outpatient clinics and 36.8% were hospitalized patients. Seventy eight percent of the patients had gastroenteritis, 10.7% had septicemia/local infection, 9.8% had typhoid/paratyphoid fever and 1.5% were carriers. Incidence of gastroenteritis was higher in 0-5 years age group (p<0.001). Of the 620 Salmonella enterica isolates, 47.7% were S. Enteritidis, 34.7% S. Typhimurium, 6% S. Paratyphi B, 2.9% S. Typhi, 0.2% S. paratyphi A, 6.1% serogroup C1, and 2.4% serogroup C2. S. Enteritidis was the most common serotype in all provinces except for Kayseri, where S. Typhimurium was found to be the most common serotype (68.2%). Overall, the most frequently isolated serotype was S. Enteritidis, also being the most common serotype in stool and blood cultures. During the surveillance period two outbreaks have occurred, the first one by S. Enteritidis strains in Edirne, and the second one by S. Typhimurium strains in Kayseri. As a result, Salmonella infections are still a common health problem in Turkey, and active surveillance of Salmonella infections has vital importance.
Asunto(s)
Infecciones por Salmonella/microbiología , Salmonella enterica/clasificación , Adolescente , Adulto , Factores de Edad , Niño , Preescolar , Femenino , Gastroenteritis/epidemiología , Gastroenteritis/microbiología , Humanos , Incidencia , Lactante , Recién Nacido , Masculino , Persona de Mediana Edad , Fiebre Paratifoidea/epidemiología , Fiebre Paratifoidea/microbiología , Infecciones por Salmonella/epidemiología , Salmonella enterica/aislamiento & purificación , Sepsis/epidemiología , Sepsis/microbiología , Serotipificación , Turquía/epidemiología , Fiebre Tifoidea/epidemiología , Fiebre Tifoidea/microbiologíaRESUMEN
In this study, the epidemiological characteristics of malaria cases in Edirne province were investigated. Between the years of 1994-2002, a total of 317,087 blood samples were collected from soldiers in the province with selective active surveillance and from the resident population with active or passive surveillance methods, by the medical staff of Malaria Control Department and Health Centers, to search the presence of Plasmodium. In 281 of them Plasmodium spp. were detected, and the characteristics of malaria cases were investigated. Of the cases, 238 (84.7%) were detected in the first three years and mostly in September. While the indigenous cases were detected in the districts where rice planted intensely, the imported cases were detected in the districts heavily populated by military staff. Of the imported cases, 62% originated from Diyarbakir, Batman and Sanliurfa provinces (Southeast part of Turkey). P. vivax was detected as the causative agent in all blood samples except one P. ovale. This latter case has been the only one in Turkey so far and he was a student from Afghanistan. Attaching importance to fight off mosquitoes in intensely rice planted districts and strictly surveying the military staff, particularly from the region of Southern-East Anatolia, have led to successful control of the malaria cases in Edirne region.
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Malaria Vivax/epidemiología , Adolescente , Adulto , Afganistán/etnología , Niño , Preescolar , Humanos , Lactante , Malaria/etnología , Malaria/prevención & control , Malaria Vivax/prevención & control , Persona de Mediana Edad , Personal Militar/estadística & datos numéricos , Control de Mosquitos , Oryza/crecimiento & desarrollo , Plasmodium ovale , Estaciones del Año , Turquía/epidemiologíaRESUMEN
This study was designed to define the epidemiology of a food-borne outbreak caused by Salmonella enteritidis that affected only one squadron of a military battalion located in the vicinity of the city of Edirne in Turkey. The outbreak was analyzed by a standard surveillance form of the Centers for Disease Control and Prevention. The relationship between the eaten foods and cases was analyzed by Fisher's exact chi-square test, and odds ratios were calculated by a case-control study. The outbreak affected 60 of 168 soldiers in the squadron, 16 of whom were hospitalized. S.enteritidis was cultured in stools from 13 of the hospitalized soldiers and from 3 soldiers who had prepared the food. All strains were completely susceptible to antibiotics; their plasmid profiles were also identical. The highest attack rate detected was 55.7% in an omelet eaten 24 hours before (p < 0.001). Furthermore, it was the riskiest food according to the case-control study (OR=7.88; 95% CI=3.68-16.89). The food samples were unobtainable because they had been discarded. All of the hospitalized cases recovered, and none of the control cultures of stools yielded the pathogen after three weeks. In conclusion, although our results didn't indicate the exact source of the outbreak microbiologically, the omelet was considered to be the source based on the epidemiological proofs.
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Brotes de Enfermedades , Intoxicación Alimentaria por Salmonella/epidemiología , Salmonella enteritidis/aislamiento & purificación , Huevos/microbiología , Humanos , Intoxicación Alimentaria por Salmonella/etiología , Turquía/epidemiologíaRESUMEN
The aim of this study was to determine the susceptibilities to macrolides of Group A streptococcal isolates from the European section of Turkey. In the case of resistant isolates, the patterns and genetic mechanisms of erythromycin resistance were studied. Seven (2.7%) of the 260 isolates were resistant to erythromycin. Four of them showed the M phenotype and harboured mefA genes whereas three isolates showed the inducible macrolide, lincosamide and streptogramin B resistance phenotype and harboured ermTR genes. In the European section of Turkey, the current resistance rate of Group A streptococci to macrolides remains low.