Gal - T Knockout Porcine Nerve Xenografts Support Axonal Regeneration in a Rodent Sciatic Nerve Model.

BACKGROUND: Nerve xenografts harvested from transgenic α1,3-galactosyltransferase knockout (GalT-KO) pigs lack the epitope responsible for hyperacute rejection in pig-to-primate transplants. It is unknown whether these cold preserved nerve grafts support axonal regeneration in another species during and after immunosuppression. In this study, we compare outcomes between autografts and cold preserved xenografts in a rat sciatic model of nerve gap repair. METHODS: Fifty male Lewis rats had a 1 cm sciatic nerve defect repaired using either: autograft and suture (n=10); 1-week or 4-week cold preserved xenograft and suture (n=10 per group); 1-week or 4-week cold preserved xenograft and photochemical tissue bonding using a human amnion wrap (PTB/HAM) (n=10 per group). Rats with xenografts were given tacrolimus until 4 months post-operatively. At 4 and 7 months, rats were euthanized and nerve sections harvested. Monthly sciatic functional index (SFI) scores were calculated. RESULTS: All groups showed increases in SFI scores by 4 and 7 months. The autograft suture group had the highest axon density at 4 and 7 months. The largest decrease in axon density from 4 to 7 months was in the 1-week cold preserved PTB/HAM group. The only significant difference between group SFI scores occurred at 5 months, when both 1-week cold preserved groups had significantly lower scores than the 4-week cold preserved suture group. CONCLUSIONS: Our results in the rat sciatic model suggest that GalT-KO nerve xenografts may be viable alternatives to autografts and demonstrate the need for further studies of long-gap repair and comparison with acellular nerve allografts. CLINICAL RELEVANCE: This proof-of-concept study in the rat sciatic model demonstrates that cold preserved GalT-KO porcine xenografts support axonal regeneration, as well as axonal viability following immunosuppression withdrawal. These results further suggest a role for both cold preservation and photochemical tissue bonding in modulating the immunological response at the nerve repair site.

Photochemical Tissue Bonding of Amnion Allograft Membranes for Peripheral Nerve Repair: A Biomechanical Analysis.

BACKGROUND: Photochemical tissue bonding (PTB) is a technique for peripheral nerve repair in which a collagenous membrane is bonded around approximated nerve ends. Studies using PTB with cryopreserved human amnion have shown promising results in a rat sciatic nerve transection model including a more rapid and complete return of function, larger axon size, and thicker myelination than suture repair. Commercial collagen membranes, such as dehydrated amnion allograft, are readily available, offer ease of storage, and have no risk of disease transmission or tissue rejection. However, the biomechanical properties of these membranes using PTB are currently unknown in comparison to PTB of cryopreserved human amnion and suture neurorrhaphy. METHODS: Rat sciatic nerves (n = 10 per group) were transected and repaired using either suture neurorrhaphy or PTB with one of the following membranes: cryopreserved human amnion, monolayer human amnion allograft (crosslinked and noncrosslinked), trilayer human amnion/chorion allograft (crosslinked and noncrosslinked), or swine submucosa. Repaired nerves were subjected to mechanical testing. RESULTS: During ultimate stress testing, the repair groups that withstood the greatest strain increases were suture neurorrhaphy (69 ± 14%), PTB with crosslinked trilayer amnion (52 ± 10%), and PTB with cryopreserved human amnion (46 ± 20%), although the differences between these groups were not statistically significant. Neurorrhaphy repairs had a maximum load (0.98 ± 0.30 N) significantly greater than all other repair groups except for noncrosslinked trilayer amnion (0.51 ± 0.27 N). During fatigue testing, all samples repaired with suture, or PTBs with either crosslinked or noncrosslinked trilayer amnion were able to withstand strain increases of at least 50%. CONCLUSION: PTB repairs with commercial noncrosslinked amnion allograft membranes can withstand physiological strain and have comparable performance to repairs with human amnion, which has demonstrated efficacy in vivo. These results indicate the need for further testing of these membranes using in vivo animal model repairs.

Bone Marrow Stem Cells with Tissue-Engineered Scaffolds for Large Bone Segmental Defects: A Systematic Review.

Critical-sized bone defects (CSBDs) represent a significant clinical challenge, stimulating researchers to seek new methods for successful bone reconstruction. The aim of this systematic review is to assess whether bone marrow stem cells (BMSCs) combined with tissue-engineered scaffolds have demonstrated improved bone regeneration in the treatment of CSBD in large preclinical animal models. A search of electronic databases (PubMed, Embase, Web of Science, and Cochrane Library) focused on in vivo large animal studies identified 10 articles according to the following inclusion criteria: (1) in vivo large animal models with segmental bone defects; (2) treatment with tissue-engineered scaffolds combined with BMSCs; (3) the presence of a control group; and (4) a minimum of a histological analysis outcome. Animal research: reporting of in Vivo Experiments guidelines were used for quality assessment, and Systematic Review Center for Laboratory animal Experimentation's risk of bias tool was used to define internal validity. The results demonstrated that tissue-engineered scaffolds, either from autografts or allografts, when combined with BMSCs provide improved bone mineralization and bone formation, including a critical role in the remodeling phase of bone healing. BMSC-seeded scaffolds showed improved biomechanical properties and microarchitecture properties of the regenerated bone when compared with untreated and scaffold-alone groups. This review highlights the efficacy of tissue engineering strategies for the repair of extensive bone defects in preclinical large-animal models. In particular, the use of mesenchymal stem cells, combined with bioscaffolds, seems to be a successful method in comparison to cell-free scaffolds.

Dental perspective on Sjõgren’s syndrome: literature review / Perspectiva odontológica del síndrome de Sjõgren: revisión de literatura

The human body releases around 500-600mL of saliva daily, however when values of unstimulated whole saliva range from 0.1 to 0.2mL/ min, there is a condition called Hyposalivation or hyposialia. Hyposalia is characterized by a large number of systemic conditions, including Sjõgren’s syndrome, a chronic autoimmune disease that affects between 0.1 and 3 percent of the world population and is characterized by exocrinopathy of the salivary glands leading to glandular hypofunction and thus decreasing the normal salivary flow. Saliva is part of innate immunity, when there is a decrease in protein secretion, numerous oral manifestations occur such as dental caries, candidiasis, gingival disease, angular cheilitis, lymphomas of the salivary glands, dysphagia, erythematous and fissured tongue, among others. Currently there is no defined dental treatment, however there are alternative treatments by sialogogues and salivary substitutes, plus non-pharmacological therapies, which seek to maintain the ecology and oral conditions stable, in addition to preventive and restorative dental treatment for lesions already established as a consequence of the disease. The aim of this study is to conduct a literature review on the characteristics, classification, oral manifestations and dental management of Sjõgren’s syndrome...

El ser humano secreta alrededor de 500 a 600 mL de saliva diariamente, sin embargo, al encontrarse valoresde 0.1 - 0.2 mL/min de saliva en reposo se presenta una condición llamada hiposalivación o hiposialia, la cual puedeser manifestada por una numerosa cantidad de condiciones sistémicas, entre ellas el síndrome de Sjõgren, la cual es una enfermedad autoinmune crónica presente en entre el 0.1 y3% de la población mundial, y es caracterizada por exocrinopatíade las glándulas salivales conllevando a la hipofunción glandular y disminuyendo así el flujo salival normal.Debido a que la saliva forma parte de la inmunidad innata, al presentarse una disminución en su secreción proteica sedesencadenan numerosas manifestaciones orales, tales comocaries dental, candidiasis, enfermedad gingival, queilitis angular, linfomas de las glándulas salivales, disfagia, lenguaeritematosa y fisurada, entre otras. Actualmente no existe un tratamiento odontológico definido, sin embargo se tienen alternativas de tratamiento mediante fármacos sialogogos ysustitutos salivales, además de terapias no farmacológicas, las cuales intentan mantener la ecología y las condiciones orales estables, además de los tratamientos odontológicos preventivosy restaurativos para lesiones ya establecidas por consecuenciade la enfermedad. El objetivo del presente estudio es realizar una revisión de literatura sobre las características, criterios de clasificación, manifestaciones orales y el manejoodontológico del Síndrome de Sjõgren...

Algunas manifestaciones socioculturales y económicas del tabaquismo en México / Some sociocultural and economic manifestations of tobaccoism in Mexico

Introducción: La planta de tabaco probablemente ha sido una de las plantas que ha transformado el mundo y es, en la actualidad, considerada como causante etiológica de múltiples patologías, sin embargo, al realizar un viaje histórico, sus antecedentes son eminentemente míticos, religiosos y terapéuticos. Objetivo: El presente trabajo tiene la finalidad de analizar los antecedentes existentes del tabaco en México desde su descubrimiento hasta el siglo XIX. Desarrollo temático: A partir del descubrimiento de América, y el análisis de sus características por Sahagún, se evidenció la nobleza de la planta desde el punto de vista mítico-religioso y parte fundamental en la economía de México posterior a la conquista. Tiempo más tarde, la planta del tabaco se utilizó con fines medicinales en especial en el tratamiento de diferentes entidades como el asma, la cefalea e inclusive en las pacientes embarazadas. Conclusión: De los antecedentes históricos se desprende que la magia del tabaco se trasformó con el devenir del tiempo en una planta desmitificada y dañina para el ser humano, e irónicamente de importancia económica

Alteraciones hepáticas en pacientes con sindrome de inmunodeficiencia adquirida. Experiencia del Hospital General de México, S.S / Hepatic manifestations of AIDS. Experience of the Hospital General de México, S.S.

Se revisaron los hallazgos clínicos, de laboratorio e histopatológicos en biopsias hepáticas que se obtuvieron de 11 pacientes con síndrome de inmunodeficiencia adquirida (SIDA) o complejo relacionado al SIDA que cursaron con alteración en las pruebas de funionamiento hepático, hepatomegalia y/o fiebre de causa desconocida. Se revisaron también los hallazgos de autopsia de 12 pacientes con esta enfermedad. El diagnóstico hepatológico más común en el material de biopsia fue de hepatitis granulomatosa: en dos casos se asoció a infección por microbacterias, en uno a fiebre tifoidea e infección por citomegalovirus y en uno a uno a probable fiebre Q; en los dos casos restantes se desconoce la etiología de los granulomas. En los pacientes con hepatitis granulomatosa se encontró con mayor frecuencia hepatomegalia, niveles séricos de transaminasa glutámico-pirúvica más bajos que en los pacientes con hepatitis no granulomatosa. En el material de autopsia se encontró hepatitis granulomatosa en 4 casos, 3 asociados a tuberculosis y 1 a toxoplasmosis. En base a estas observaciones y a lo informado en la literatura se concluye que la biopsia hepática puede ser de utilidad para establecer un diagnóstico preciso y en la toma de decisiones terapéuticas en aquellos pacientes que pertenezcan a los grupos de riesgo que desarrollan hepatitis granulomatosa frecuentemente