Animal model of corneal ectasia in rabbits by intrastromal injection of type II collagenase

INTRODUCTION

Collagenase II has been used to induce experimental keratoconus in animal models. However, its effect when administered by intrastromal injection has not been studied, so the purpose of this study was to study the effects of intrastromal injection of collagenase II on corneal surface and corneal morphology.

METHODS

Six New Zealand rabbits were used, collagenase II was administered by intrastromal injection (5μL of 2.5mg/mL) in the right eyes and balanced salt solution in the left eyes. Keratometry was performed to evaluate curvature alteration, also at day 7 corneas were obtained and Hematoxylin-Eosin staining was performed to examine morphologic changes. Likewise, changes in type I collagen expression were investigated by Sirius Red staining and semiquantitative PCR.

RESULTS

K1, K2 and Km presented differences in the means with statistically significant changes. The morphological changes that were demonstrated were degradation and irregular arrangement of the corneal stroma, increase in the cellular density of keratocytes and slight cellular infiltration. Finally, it was demonstrated that there is greater expression of type I collagen fibers in the experimental group as opposed to the controls and the thickness of the fibers also increased due to the action of collagenase II, however, in terms of genetics there were no changes in the expression of type I collagen at molecular level between the control and experimental groups.

CONCLUSIONS

Collagenase II administered by intrastromal injection is able to induce changes in the corneal surface and stroma, being able to simulate a model of keratoconus.

A Physiotherapy Treatment Plan for Post-COVID-19 Patients That Improves the FEV1, FVC, and 6-Min Walk Values, and Reduces the Sequelae in 12 Sessions

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causal agent of Coronavirus disease 2019 (COVID-19), a pandemic disease declared in 2020. The clinical manifestations of this pathology are heterogeneous including fever, cough, dyspnea, anosmia, headache, fatigue, taste dysfunction, among others. Survivors of COVID-19 have demonstrated several persistent symptoms derived from its multisystemic physiopathology. These symptoms can be fatigue, dyspnea, chest pain, dry and productive cough, respiratory insufficiency, and psychoemotional disturbance. To reduce and recover from the post-COVID-19 sequelae is fundamental an early and multifactorial medical treatment. Integral post-COVID-19 physiotherapy is a tool to reduce dyspnea, improve lung capacity, decrease psychoemotional alterations, as well as increase the muscle strength affected by this disease. Thus, the aim of this study was to establish a novel physiotherapeutic plan for post-COVID-19 patients, evaluating the effect of this treatment in the reduction of the sequelae in terms of lung capacity, cardio-respiratory, and muscular strength improvements. This was a cross-sectional study in which a protocol of 12 sessions in 4 weeks of physiotherapy was implemented in the patients enrolled. We conducted a medical assessment, an interview, a DASS-21 test, a spirometry, a 6-min walk test, and a hand dynamometer test to evaluate the post-COVID condition of patients before and after the sessions. A total of 42 patients participated in the program. Results of this work showed a decrease of around 50% of post-COVID-19 sequelae and an improvement in the psychoemotional status of patients. Also, we observed an increase of 7.16% in the FEV1 value and 7.56% for FVC. In addition, the maximal functional capacity increased by 0.577 METs, the 6-min walk test performance increased by 13%, and the SpO2 improved by 1.40%. Finally, the handgrip strength test showed an improvement in the left hand and right hand of 2.90 and 2.24 Kg, respectively. We developed this study to propose a novel methodology to provide information for a better treatment and management of post-COVID-19 patients.