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1.
Respiration ; 103(2): 79-87, 2024.
Artículo en Inglés | MEDLINE | ID: mdl-38325355

RESUMEN

INTRODUCTION: Chronic thromboembolic pulmonary disease (CTEPD) consists of persistent pulmonary vascular obstruction on imaging and involves long-term functional limitations, with or without chronic thromboembolic pulmonary hypertension (CTEPH). The aim of this study was to evaluate the incidence and risk factors of both persistent pulmonary vascular defects and CTEPH after hospitalization in patients with COVID-19 and PE during a 2-year follow-up. METHODS: A prospective observational study was carried out in a tertiary hospital center. Patients were hospitalized between March 2020 and December 2021 with a diagnosis of PE during SARS-CoV-2 infection. Patients received anticoagulant treatment for at least 3 months and were followed up for 2 years. Between the third and fourth months after discharge, all patients were evaluated for the presence of residual thrombotic defects by CTPA and/or perfusion pulmonary scintigraphy. Clinical findings, lung function tests with DLCO, exercise capacity, and echocardiograms were also assessed. RESULTS: Of the 133 patients included, 18% had persistent thrombotic defects on lung imaging at follow-up. The incidence of CTEPD was 0.75% at 2 years of follow-up. Patients with persistent defects were significantly older, had a higher prevalence of systemic arterial hypertension, higher D-dimer and NT-proBNP levels, and more severe PE at diagnosis. Furthermore, there was a higher prevalence of right ventricular dysfunction on echocardiogram at diagnosis of PE (25.0% vs. 2.7%, p = 0.006). This was the only variable independently related to persistent defects in multivariate analyses (OR: 8.13 [95% CI: 1.82-36.32], p = 0.006). CONCLUSION: The persistence of thrombotic defects after PE is a common finding after SARS-CoV-2 infection, affecting 18% of the population. However, the incidence of CTEPH appears to be lower (0.75%) in COVID-19-related PE compared to that previously observed in PE unrelated to COVID-19.


Asunto(s)
COVID-19 , Hipertensión Pulmonar , Embolia Pulmonar , Tromboembolia , Humanos , Enfermedad Crónica , COVID-19/complicaciones , Hipertensión Pulmonar/epidemiología , Hipertensión Pulmonar/etiología , Hipertensión Pulmonar/diagnóstico , Pulmón , Embolia Pulmonar/diagnóstico por imagen , Embolia Pulmonar/epidemiología , Embolia Pulmonar/etiología , SARS-CoV-2 , Tromboembolia/complicaciones , Estudios Prospectivos
2.
Artículo en Inglés | MEDLINE | ID: mdl-38059137

RESUMEN

Introduction: Machine learning (ML)-based facial nerve injury (FNI) forecasting grounded on multicentric data has not been released up to now. Three distinct ML models, random forest (RF), K-nearest neighbor, and artificial neural network (ANN), for the prediction of FNI were evaluated in this mode. Methods: A retrospective, longitudinal, multicentric study was performed, including patients who went through parotid gland surgery for benign tumors at three different university hospitals. Results: Seven hundred and thirty-six patients were included. The most compelling aspects related to risk escalation of FNI were as follows: (1) location, in the mid-portion of the gland, near to or above the main trunk of the facial nerve and at the top part, over the frontal or the orbital branch of the facial nerve; (2) tumor volume in the anteroposterior axis; (3) the necessity to simultaneously dissect more than one level; and (4) the requirement of an extended resection compared to a lesser extended resection. By contrast, in accordance with the ML analysis, the size of the tumor (>3 cm), as well as gender and age did not result in a determining favor in relation to the risk of FNI. Discussion: The findings of this research conclude that ML models such as RF and ANN may serve evidence-based predictions from multicentric data regarding the risk of FNI. Conclusion: Along with the advent of ML technology, an improvement of the information regarding the potential risks of FNI associated with patients before each procedure may be achieved with the implementation of clinical, radiological, histological, and/or cytological data.

3.
J Clin Med ; 12(12)2023 Jun 20.
Artículo en Inglés | MEDLINE | ID: mdl-37373850

RESUMEN

BACKGROUND: The post-acute sequelae of SARS-CoV-2 (PASC) infection have caused a significant impact on our health system, but there is limited evidence of approved drugs focused on its prevention. Our objective was to identify risk factors that can determine the presence of PASC, with special attention to the treatment received in the acute phase, and to describe the profile of persistent symptoms in a multidisciplinary Post-Coronavirus Disease-19 (COVID-19) Unit. METHODS: This one-year prospective observational study included patients following an acute COVID-19 infection, irrespective of whether they required hospital admission. A standardized symptom questionnaire and blood sampling were performed at the first follow-up visit, and demographic and clinical electronic data were collected. We compared subjects with PASC with those who had fully recovered. Multivariate logistic regression was performed to identify factors associated with PASC in hospitalized patients, and Kaplan-Meier curves were used to assess duration of symptoms according to disease severity and treatments received in the acute phase. RESULTS: 1966 patients were evaluated; 1081 had mild disease, 542 moderate and 343 severe; around one third of the subjects had PASC, and were more frequently female, with obesity, asthma, and eosinophilia during acute COVID-19 disease. Patients who received treatment with dexamethasone and remdesivir during the course of the acute illness showed a lower median duration of symptoms, compared with those who received none of these treatments. CONCLUSION: Treatment with dexamethasone and/or remdesivir may be useful to reduce the impact of PASC secondary to SARS-CoV-2 infection. In addition, we identified female gender, obesity, asthma, and disease severity as risk factors for having PASC.

4.
Eur Biophys J ; 52(3): 175-187, 2023 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-37291414

RESUMEN

A meaningful dilemma in ribosome translocation arising from experimental facts is that, although the ribosome-mRNA interaction force always has a significant magnitude, the ribosome still moves to the next codon on the mRNA. How does the ribosome move to the next codon in the sequence while holding the mRNA tightly? The hypothesis proposed here is that ribosome subunits alternate the grip of the ribosome on the mRNA, freeing the other subunit of such interaction for a while, thus allowing its motion to the following codon. Based on this assumption, a single-loop cycle of ribosome configurations involving the relative position of its subunits is elaborated. When its dynamic is modeled as a Markov network, it gives expressions for the average ribosome translocation speed and stall force as functions of the equilibrium constants among the proposed ribosome configurations. The calculations have a reasonable agreement with experimental results, and the succession of molecular events considered here is consistent with current biomolecular concepts of the ribosome translocation process. Thus, the alternative displacements hypothesis developed in the present work suggests a feasible explanation of ribosome translocation.


Asunto(s)
Biosíntesis de Proteínas , Ribosomas , Ribosomas/genética , Ribosomas/metabolismo , Codón/genética , Codón/metabolismo , ARN Mensajero/genética , ARN Mensajero/metabolismo , Movimiento (Física)
5.
Eur Arch Otorhinolaryngol ; 280(2): 869-876, 2023 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-36102986

RESUMEN

INTRODUCTION: Nowadays, 70% of patients in Europe and the USA are affected by a p16 + , potentially HPV driven oropharyngeal squamous cell carcinoma. However, despite the improved survival rate in this group, the quality-of-life remains low in cases which neck dissection took place. In this vein, in recent years, some surgeons have considered to avoid dissection of level IIB, proposing a supra-selective non-IIb neck dissection. MATERIALS AND METHODS: A retrospective, longitudinal, multicentric study was conducted, including patients with pathologically confirmed primary HPV + or HPV - OPSCC who went through surgical treatment for the primary lesion and neck dissection. RESULTS: 141 patients were included. Among them, 99 (70.2%) were male and 42 (29.8%) were female. The mean age was 62 ± 9 years (range 36-81). The most frequent anatomical location was the tonsil in 63 (44.7%) of patients. The most common approach was the classic transoral oropharyngectomy in 51 (36.2%) patients. Immunohistochemistry for p16 was positive in 62 (44%) patients. One-hundred and five (74.5%) patients received a unilateral ND, and a 36 (25.5%) a bilateral ND. Of those, a 12.8% (18/141) of patients were level IIb LN + . According to our results, level IIb ND should be considered in patients underwent therapeutic ND with positive LN metastasis in level IIa (OR = 9.83; 95% CI 3.463-27.917) or III (OR = 6.25; 95% CI 2.158-18.143), advanced (T3/T4) oropharyngeal primary tumors (OR = 3.38; 95% CI 1.366-8.405), and patients with ENE (OR = 6.56; 95% CI 2.182-19.770), regardless of p16 status. CONCLUSIONS: According to our results, level IIb ND should be considered in patients who underwent therapeutic ND with positive LN metastasis in level IIa or III, advanced oropharyngeal primary tumors, and patients with ENE, independently of p16 status. Prospective data are necessary to definitively ensure the safety of omitting ipsilateral or contralateral level IIb ND in cN - patients with early stage disease.


Asunto(s)
Neoplasias Orofaríngeas , Infecciones por Papillomavirus , Carcinoma de Células Escamosas de Cabeza y Cuello , Adulto , Anciano , Anciano de 80 o más Años , Femenino , Humanos , Masculino , Persona de Mediana Edad , Ganglios Linfáticos/patología , Metástasis Linfática/patología , Disección del Cuello/métodos , Estadificación de Neoplasias , Neoplasias Orofaríngeas/patología , Neoplasias Orofaríngeas/cirugía , Infecciones por Papillomavirus/patología , Estudios Prospectivos , Estudios Retrospectivos , Carcinoma de Células Escamosas de Cabeza y Cuello/cirugía , Carcinoma de Células Escamosas de Cabeza y Cuello/patología
6.
Artículo en Inglés | MEDLINE | ID: mdl-36241027

RESUMEN

Metastatic carcinoma of unknown primary (CUP) to cervical lymph nodes represents less than 5% of all head and neck malignancies. Recent publications support the use of transoral surgery during the diagnosis work-up, and transoral endoscopic ultrasonic surgery represent a recently described alternative technique in transoral surgery. A pilot study to assess the feasibility of trans-oral ultrasonic base of tongue (BOT) mucosectomy and bilateral tonsillectomy approach in CUP diagnosis work-up was conducted. Ten patients were included consecutively. In 2 cases (20%) the primary was found, in one case in the right tonsil, and another one in the left BOT. According to our results, the use of trans-oral ultrasonic surgery to perform the base of tongue mucosectomy and bilateral tonsillectomy in CUP patient's during the diagnosis work-up represents an effective option in patients with good anatomical exposure.


Asunto(s)
Carcinoma , Cirugía Endoscópica por Orificios Naturales , Neoplasias Primarias Desconocidas , Procedimientos Quirúrgicos Robotizados , Procedimientos Quirúrgicos Ultrasónicos , Humanos , Neoplasias Primarias Desconocidas/cirugía , Neoplasias Primarias Desconocidas/etiología , Neoplasias Primarias Desconocidas/patología , Ultrasonido , Proyectos Piloto , Procedimientos Quirúrgicos Robotizados/métodos , Cirugía Endoscópica por Orificios Naturales/métodos
8.
Eur Arch Otorhinolaryngol ; 280(1): 23-37, 2023 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-35941283

RESUMEN

PURPOSE: Vascular perfusion research has been dedicated to identify inexpensive, effective, and easy to use methods to assess free flap perfusion for both buried and non-buried flaps. METHODS: Systematic review of complications in patients underwent Head and Neck microsurgical reconstruction and vascular implantable Doppler monitoring. RESULTS: Sixteen articles were included for qualitative analysis. 2535 (92.2%) patients received IDP monitorization. Venous thrombosis was the most common vascular complication effecting 28 (1.1%). Regarding complications potentially related to the use of the IDP, just one study described the presence of granuloma formation along the suture line in 2 (0.07%) patients. CONCLUSIONS: Our findings indicated that Cook-Swartz IDP will represents a safe and effective device for FF monitoring in HN reconstructive micro-surgery. A detailed prospective registration of the results and complications related to the use of IDP remains mandatory to precisely estimate results, cost, and complications.


Asunto(s)
Colgajos Tisulares Libres , Humanos , Estudios Prospectivos , Monitoreo Fisiológico , Estudios Retrospectivos , Colgajos Tisulares Libres/efectos adversos , Colgajos Tisulares Libres/irrigación sanguínea , Ultrasonografía Doppler/métodos
9.
Cureus ; 14(9): e28971, 2022 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-36237817

RESUMEN

The need for a total or subtotal nose resection represents a dramatic situation for any patient and a challenge for the reconstructive surgeon. Because even in the most skillful hands, an optimal result may be difficult to achieve. In this way, sometimes a free flap reconstruction is needed. A subtotal nasal reconstruction is presented using a fasciocutaneous free flap supported by computer-aided design (CAD), computer-aided manufacturing (CAM), and novel 3D printed guide to recreate the nasal cartilage framework. A successfully free flap reconstruction of the nasal framework was achieved supported by the CAD/CAM 3D printed template. We present a novel approach for nasal total or subtotal reconstruction using a CAD/CAM 3D printed model to create the nasal framework, based on the anatomical and radiological evaluation of the patient.

10.
Artículo en Inglés | MEDLINE | ID: mdl-36113921

RESUMEN

INTRODUCTION: The gracilis muscle free flap has gained popularity in head and neck reconstruction due to minimal donor-site morbidity, reliable vascular pedicle, strong muscular component, and possibility to perform nerve coaptation. However, almost all the existing evidence in the literature is related to its use for facial palsy reanimation. The aim of this study was therefore to review and provide a comprehensive summary of all the possible indications and outcomes of this versatile free flap in head neck reconstructive surgery. MATERIALS AND METHODS: A systematic review of the literature was conducted including articles from 1970 to 2019. All articles were examined and described. RESULTS: Twenty-seven papers published between 1994 and 2019 were identified for analysis. The evidence highlights the use of the gracilis muscle free flap for parotid, forehead and midface defects, oral tongue, oral sphincter, lower and upper lip, cheek, and oral commissure defects, among others, as the most common defects reconstructed. CONCLUSION: This flap represents an easy to harvest and versatile free flap with low donor-site morbidity and multiple proven uses in head & neck reconstruction. We therefore encourage reconstructive surgeons to include this flap in their armoury, either as a first or as a second-line option.


Asunto(s)
Parálisis Facial , Colgajos Tisulares Libres , Neoplasias de Cabeza y Cuello , Procedimientos de Cirugía Plástica , Parálisis Facial/cirugía , Neoplasias de Cabeza y Cuello/complicaciones , Neoplasias de Cabeza y Cuello/cirugía , Humanos , Cuello
11.
Artículo en Inglés | MEDLINE | ID: mdl-35908816

RESUMEN

INTRODUCTION: Head & neck surgery encompasses a variety of surgical approaches for benign and malignant conditions. Due to the complexity in treating patients with head and neck pathology, it is necessary to adhere to basic surgical principles to decrease complications. Among them, surgical site infection can be prevented using a surgery quality protocol including the correct use of antibiotics and optimization of nutritional status. MATERIALS AND METHODS: A survey was sent through the YO-IFOS and SEORL-CCC international mailing list. RESULTS: A total of 435 surgeons completed the survey. Of the respondents, 97.7% confirm that they scrub their hands before surgery, 40.9% respondents recommend nutritional support according to sign and symptoms, 60.9% use of antibiotic prophylaxis in clean surgery and just 9.2% use clindamycin in combination. CONCLUSION: This survey has broadened the scope regarding H&N surgical safety around the globe. Identifying innovative ways in which surgical care may be improved is mandatory.


Asunto(s)
Neoplasias de Cabeza y Cuello , Infección de la Herida Quirúrgica , Antibacterianos/uso terapéutico , Profilaxis Antibiótica/métodos , Humanos , Infección de la Herida Quirúrgica/prevención & control , Encuestas y Cuestionarios
13.
Oncol Ther ; 10(1): 241-252, 2022 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-35357676

RESUMEN

INTRODUCTION: Pharyngocutaneous fistula (PCF) remains the most frequent complication following total laryngectomy (TL). Pharyngeal closure with a surgical stapler (SAPC) has been proposed as an effective closure technique that decreases the rate of PCF, reduces surgical time, decreases the length of hospital stay, and shortens the time required before safely initiating oral feeding. METHODS: This study involved a systematic review and meta-analysis of patients with laryngeal cancer who underwent TL and with subsequent stapler pharyngeal closure, in order to analyse the current literature regarding the role of SAPC after TL. RESULTS: The incidence of PCF in the stapler-assisted suture group (SASG) was 9.5% (95% CI 8.2-15.9%), with a mean absolute deviation of 1.12, while in the hand-suture group (HSG) group the incidence was 23.4% (95% CI 23-26.1%), with a mean absolute deviation of 5.71 (p = 0.01). CONCLUSIONS: SAPC may decrease the risk of PCF in patients following TL. Based on the current data, SAPC appears to shorten the surgical time and the length of hospital stay. Nevertheless, prospective randomized trials are required to validate these findings.

14.
Int. arch. otorhinolaryngol. (Impr.) ; 26(1): 103-110, Jan.-Mar. 2022. tab
Artículo en Inglés | LILACS-Express | LILACS | ID: biblio-1364921

RESUMEN

Abstract Introduction Head and neck surgery remains a complex field; the patients can suffer important functional or life-threating complications after treatment that need unplanned readmissions, increasing the cost related to the treatment. Objective To evaluate the incidence risk factors and causes associated with 30-day unplanned hospital readmission and visit to the emergency room (ER) after surgery for head and neck cancer. Methods Prospective, longitudinal, nonrandomized study. Results A total of 834 patients were included, 726 in the major surgery group and 108 in the minor surgery group. The 30-day readmission rate for all causes was of 7,9% for the patients treated by a major surgery and of 0% for the patients treated in the outpatient clinic for minor procedures, to a total readmission rate of 6,8%. The rate of visit to the emergency room for all causes in the first 30 days was of 14% for the patients treated by a major surgery and of 2,7% for the patients treated in the outpatient clinic. Conclusion Major surgery, the American Society of Anesthesiologists (ASA) status and type of wound are conditions related to unplanned readmission or visit to the ER in the first 30 day after discharge. The most commonly associated causes are infections or wound complications. An evidence-based risk stratification of the patients can be important to improve decision-making and resource utilization. An educational strategy can provide possible ways to improve the rate of readmission and reduce the amount of money expended by healthcare systems.

15.
Int Arch Otorhinolaryngol ; 26(1): e103-e110, 2022 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-35096166

RESUMEN

Introduction Head and neck surgery remains a complex field; the patients can suffer important functional or life-threating complications after treatment that need unplanned readmissions, increasing the cost related to the treatment. Objective To evaluate the incidence risk factors and causes associated with 30-day unplanned hospital readmission and visit to the emergency room (ER) after surgery for head and neck cancer. Methods Prospective, longitudinal, nonrandomized study. Results A total of 834 patients were included, 726 in the major surgery group and 108 in the minor surgery group. The 30-day readmission rate for all causes was of 7,9% for the patients treated by a major surgery and of 0% for the patients treated in the outpatient clinic for minor procedures, to a total readmission rate of 6,8%. The rate of visit to the emergency room for all causes in the first 30 days was of 14% for the patients treated by a major surgery and of 2,7% for the patients treated in the outpatient clinic. Conclusion Major surgery, the American Society of Anesthesiologists (ASA) status and type of wound are conditions related to unplanned readmission or visit to the ER in the first 30 day after discharge. The most commonly associated causes are infections or wound complications. An evidence-based risk stratification of the patients can be important to improve decision-making and resource utilization. An educational strategy can provide possible ways to improve the rate of readmission and reduce the amount of money expended by healthcare systems.

16.
Pathol Oncol Res ; 27: 598292, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-34257550

RESUMEN

The acquisition of driver mutations in non-tumoral cells appears to be very important during the carcinogenesis of adenocarcinoma (ADC). Recent studies suggest that cancer-related mutations may not necessarily be present only in malignant cells, but also in histologically "healthy cells". Objective: to demonstrate the presence of EGFR or KRAS mutations in non-tumoral lung cells in subjects with ADC and negative mutational status. Results: mutations in EGFR or KRAS oncogenes were identified in the normal lung in 9.7% of the subjects. Exon 21 substitution L858R in EGFR was detected in two cases while the exon 19 deletion E746-A750 in the EGFR, the G12C and G12D substitutions in the KRAS were detected once. One patient presented three different mutations in the normal lung parenchyma (EGFR_L858R, KRAS_G12C and KRAS_G12D). The negative-mutation status of the tumor and the mutations detected in the "normal lung" were confirmed using highly sensitive and specific TaqMan PCR (CAST-PCR). No differences were found in terms of progression, progression-free survival or overall survival during the 18 months follow-up. Conclusions: These results confirm the presence of driver mutations in the histologically normal lung parenchyma cells in the absence of mutations coexisting with the primary tumor.


Asunto(s)
Adenocarcinoma del Pulmón/patología , Biomarcadores de Tumor/genética , Neoplasias Pulmonares/patología , Mutación , Tejido Parenquimatoso/patología , Proteínas Proto-Oncogénicas p21(ras)/genética , Adenocarcinoma del Pulmón/genética , Anciano , Anciano de 80 o más Años , Estudios de Casos y Controles , Receptores ErbB/genética , Femenino , Estudios de Seguimiento , Humanos , Neoplasias Pulmonares/genética , Masculino , Persona de Mediana Edad , Tejido Parenquimatoso/metabolismo , Pronóstico
17.
ORL J Otorhinolaryngol Relat Spec ; 83(5): 372-380, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-34010845

RESUMEN

INTRODUCTION: Functional neck dissection (FND) represents a surgical procedure usually associated with less morbidity. METHODS: An observational, retrospective, analysis of patients diagnosed with any type of head and neck malignancy was designed to summarize and report the incidence of postoperative complications in patients undergoing FND including just those levels described for selective neck dissections in a tertiary university hospital between June 2016 and June 2019. RESULTS: 131 patients met the inclusion criteria. The total number of sides studied was 200. 40.5% of the patients suffer a complication in the postoperative period, being the spinal accessory nerve (SAN) injury the most common complication (10%). We did not find any statistical -correlation between the previous organ-preservation treatments and surgical complications (p = 0.207). An advanced T stage (p = 0.009) and the need of bilateral FND (p = 0.034) were significantly correlated with a higher risk of surgical complications. CONCLUSION: FND represents a useful technique. In this study, 40.5% of the patients suffer a complication in the postoperative period, being the SAN injury the most common complication. However, these data contribute to increasing our knowledge about surgical complications related to FND.


Asunto(s)
Traumatismos del Nervio Accesorio , Neoplasias de Cabeza y Cuello , Nervio Accesorio , Neoplasias de Cabeza y Cuello/cirugía , Humanos , Disección del Cuello/efectos adversos , Complicaciones Posoperatorias/epidemiología , Complicaciones Posoperatorias/etiología , Estudios Retrospectivos
18.
Micromachines (Basel) ; 12(3)2021 Mar 10.
Artículo en Inglés | MEDLINE | ID: mdl-33802204

RESUMEN

Photopolymerized microparticles are made of biocompatible hydrogels like Polyethylene Glycol Diacrylate (PEGDA) by using microfluidic devices are a good option for encapsulation, transport and retention of biological or toxic agents. Due to the different applications of these microparticles, it is important to investigate the formulation and the mechanical properties of the material of which they are made of. Therefore, in the present study, mechanical tests were carried out to determine the swelling, drying, soluble fraction, compression, cross-linking density (Mc) and mesh size (ξ) properties of different hydrogel formulations. Tests provided sufficient data to select the best formulation for the future generation of microparticles using microfluidic devices. The initial gelation times of the hydrogels formulations were estimated for their use in the photopolymerization process inside a microfluidic device. Obtained results showed a close relationship between the amount of PEGDA used in the hydrogel and its mechanical properties as well as its initial gelation time. Consequently, it is of considerable importance to know the mechanical properties of the hydrogels made in this research for their proper manipulation and application. On the other hand, the initial gelation time is crucial in photopolymerizable hydrogels and their use in continuous systems such as microfluidic devices.

20.
Eur Phys J E Soft Matter ; 44(2): 9, 2021 Mar 08.
Artículo en Inglés | MEDLINE | ID: mdl-33683520

RESUMEN

In this work we assume that the ribosome propels itself during the translocation step of the translation process of protein synthesis by running a cycle of stochastically generated conformational changes involving its two subunits. This cycle includes only two experimentally found ribosome shape changes. The main result is an analytic expression for ribosome's average swimming speed on a polysome, where the ribosome is in the presence of other ribosomes. Relevant geometric parameters of ribosome deformations are calculated first by solving a deterministic problem where the ribosome runs a cycle of prescribed conformational changes. The method of reflections and pairwise additivity are used to obtain the stresses and forces needed to apply the multiparticle reciprocal theorem. Ribosome's average velocity when it runs the corresponding stochastic cycle of deformations is calculated assuming independence among the conformational cycles of different ribosomes on the polysome. The results obtained show that swimming in tandem on the polysome allows the ribosome to reach any typical subcellular speed with deformations whose amplitude is of a smaller size than when it swims alone in the fluid. Also, the flow organized by its swimming stroke becomes more determinant for its motion than random diffusion, compared to the solitary ribosome.


Asunto(s)
Polirribosomas/química , Ribosomas/química , Simulación por Computador , Difusión , Modelos Biológicos , Conformación Molecular , Movimiento (Física) , Relación Estructura-Actividad
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