Clinical practice guidelines for the diagnosis and management of Charcot-Marie-Tooth disease

INTRODUCTION

Charcot-Marie-Tooth (CMT) disease is classified considering the neurophysiological and histological findings, the inheritance pattern and the underlying genetic defect. In recent years, with the advent of next generation sequencing, genetic complexity has increased exponentially, expanding the knowledge about disease pathways, and having an impact in clinical management. The aim of this guide is to offer recommendations for the diagnosis, prognosis, monitoring and treatment of this disease in Spain.

MATERIAL AND METHODS

This consensus guideline has been developed by a multidisciplinary panel encompassing a broad group of professionals including neurologists, neuropediatricians, geneticists, rehabilitators, and orthopaedic surgeons.

RECOMMENDATIONS

The diagnosis is based in the clinical characterization, usually presenting with a common phenotype. It should be followed by an appropriate neurophysiological study that allows for a correct classification, specific recommendations are established for the parameters that should be included. Genetic diagnosis must be approached in sequentially, once the PMP22 duplication has been ruled out if appropriate, a next generation sequencing should be considered taking into account the limitations of the available techniques. To date, there is no pharmacological treatment that modifies the course of the disease, but symptomatic management is important, as are the rehabilitation and orthopaedic considerations. The latter should be initiated early to identify and improve the patient's functional impairments, including individualised exercise guidelines, orthotic adaptation, and assessment of conservative surgeries such as tendon transpositions. The follow-up of patients with CMT is exclusively clinical, ancillary testing are not necessary in routine clinical practice.

P-351 Ethical challenges posed by an increase of surplus frozen embryos in Argentinean fertility centers

Study question

Can an increase in the quantity of frozen embryos lead to more difficulties in embryo disposition decisions (EDD)?

Summary answer

EDD posed clinical and ethical challenges and might be influenced by having more available embryos, due to changes in the laboratory procedures.

What is known already

Previous research suggests that many people find EDD difficult and emotionally distressing. Patients face ambivalence during the decision-making process which could lead to embryo abandonment. Regulation of embryo dispositions varies among countries, but in the Latin American context, the regulatory gap generates insecurities in healthcare professionals. Cultural values towards the embryo can be associated with discomfort, guilt, or psychological burden. Studies suggest that patients often feel that they are unable to make a satisfactory decision when presented with the current embryo disposition options. Thus, other ‘solutions’, such as the request for nonreproductive transfer, appear and raises ethical questions and concerns.

Study design, size, duration

This is an observational study which follows a thematic literature review, that identifies the main reasons for difficulties with embryo disposition decisions, in different countries. It focuses on the regulatory background of the principal ART providers worldwide to discuss the best course of action for Argentina, that faces the problem of EDD at a regulatory level. To inform the discussion, a comparative survey from an Argentinean context, was carried out.

Participants/materials, setting, methods

Most fertility clinics in Argentina are private entities, as there are very few public providers. Access to ART treatments has been regulated since 2013, but the law fails to define a number of important issues, including EDD and national registries. An online survey was sent to all reproductive facilities to collect data on storage content and the results were complemented with data from the Latin American Register (RedLara) and the Argentine Registry of Assisted Fertilization.

Main results and the role of chance

The survey results showed that in 2017, there were approximately 54.432 frozen embryos stored in 46 Argentinean fertility centers and the total amount in 2020 reached 91.724 stored in 54 centers. Despite the number of treatment cycles (IVF + OD) being constant between 2017 and 2020 (with a slight increase of 8%), the number of frozen embryos has increased exponentially (by 68.5%). This is a consequence of the improvements in cryopreservation techniques (vitrification) and the development of more efficient ovarian stimulation protocols, that have facilitated a rise in elective single embryo transfer. These advances, coupled with an inefficient regulatory framework, generate uncertainties in physicians who might already be conflicted and therefore provide little or inadequate guidance for patients facing EDD. Three strategies could be implemented to facilitate EDD under this particular setting. First, counseling sessions at different treatment stages should be encouraged and are conducted by trained mental health professionals, who are aware of their patient’s changing attitudes towards surplus embryos. Second, both aneuploid embryos and embryos which were cryopreserved more than 10 years ago could form part of a national bank for research purposes, using classified storage content. Third, promote effective regulation that includes EDD and explicit storage limits.

Limitations, reasons for caution

The influence of the Catholic Church on policy makers regarding embryo dispositions is the main drawback. There is a need to foster a regulatory framework that considers the changes in IVF procedures and practices. On a practical level, psychosocial care is missing as part of healthcare teams’ practices.

Wider implications of the findings

The survey results revealed that IVF centers in Argentina will face an increase in euploid, aneuploid and untested frozen embryos, due to the changes registered in laboratory procedures. This tendency shows the need to discuss EDD with patients from the beginning of fertility treatment, through to its conclusion.

Trial registration number

not applicable

P–351 Ethical challenges posed by an increase of surplus frozen embryos in Argentinean fertility centers

Study question

Can an increase in the quantity of frozen embryos lead to more difficulties in embryo disposition decisions (EDD)?

Summary answer

EDD posed clinical and ethical challenges and might be influenced by having more available embryos, due to changes in the laboratory procedures.

What is known already

Previous research suggests that many people find EDD difficult and emotionally distressing. Patients face ambivalence during the decision-making process which could lead to embryo abandonment. Regulation of embryo dispositions varies among countries, but in the Latin American context, the regulatory gap generates insecurities in healthcare professionals. Cultural values towards the embryo can be associated with discomfort, guilt, or psychological burden. Studies suggest that patients often feel that they are unable to make a satisfactory decision when presented with the current embryo disposition options. Thus, other ‘solutions’, such as the request for nonreproductive transfer, appear and raises ethical questions and concerns.

Study design, size, duration

This is an observational study which follows a thematic literature review, that identifies the main reasons for difficulties with embryo disposition decisions, in different countries. It focuses on the regulatory background of the principal ART providers worldwide to discuss the best course of action for Argentina, that faces the problem of EDD at a regulatory level. To inform the discussion, a comparative survey from an Argentinean context, was carried out.

Participants/materials, setting, methods

Most fertility clinics in Argentina are private entities, as there are very few public providers. Access to ART treatments has been regulated since 2013, but the law fails to define a number of important issues, including EDD and national registries. An online survey was sent to all reproductive facilities to collect data on storage content and the results were complemented with data from the Latin American Register (RedLara) and the Argentine Registry of Assisted Fertilization.

Main results and the role of chance

The survey results showed that in 2017, there were approximately 54.432 frozen embryos stored in 46 Argentinean fertility centers and the total amount in 2020 reached 91.724 stored in 54 centers. Despite the number of treatment cycles (IVF + OD) being constant between 2017 and 2020 (with a slight increase of 8%), the number of frozen embryos has increased exponentially (by 68.5%). This is a consequence of the improvements in cryopreservation techniques (vitrification) and the development of more efficient ovarian stimulation protocols, that have facilitated a rise in elective single embryo transfer. These advances, coupled with an inefficient regulatory framework, generate uncertainties in physicians who might already be conflicted and therefore provide little or inadequate guidance for patients facing EDD. Three strategies could be implemented to facilitate EDD under this particular setting. First, counseling sessions at different treatment stages should be encouraged and are conducted by trained mental health professionals, who are aware of their patient’s changing attitudes towards surplus embryos. Second, both aneuploid embryos and embryos which were cryopreserved more than 10 years ago could form part of a national bank for research purposes, using classified storage content. Third, promote effective regulation that includes EDD and explicit storage limits.

Limitations, reasons for caution

The influence of the Catholic Church on policy makers regarding embryo dispositions is the main drawback. There is a need to foster a regulatory framework that considers the changes in IVF procedures and practices. On a practical level, psychosocial care is missing as part of healthcare teams’ practices.

Wider implications of the findings: The survey results revealed that IVF centers in Argentina will face an increase in euploid, aneuploid and untested frozen embryos, due to the changes registered in laboratory procedures. This tendency shows the need to discuss EDD with patients from the beginning of fertility treatment, through to its conclusion.

Trial registration number

Not applicable

Experience in the management of ECMO therapy as a mortality risk factor

INTRODUCTION

The extracorporeal oxygenation membrane (ECMO) is a system that provides circulatory and respiratory assistance to patients in cardiac or respiratory failure refractory to conventional treatment. It is a therapy with numerous associated complications and high mortality. Multidisciplinary management and experienced teams increase survival.

OBJECTIVE

Our purpose is to evaluate and analyse the effect of the learning curve on mortality.

METHODS

Retrospective and observational study of 31 patients, from January 2012 to December 2015. Patients were separated into 2periods. These periods were divided by the establishment of an ECMO protocol. We compared the quantitative variables by performing the Mann-Whitney U test. For the categorical qualitative variables we performed the chi-square test or Fisher exact statistic as appropriate. The survival curve was computed using the Kaplan-Meier method, and the analysis of statistical significance using the Log-rank test. Data analysis was performed with the STATA programme 14.

RESULTS

Survival curves show the tendency to lower mortality in the subsequent period (P=0.0601). The overall mortality rate in the initial period was higher than in the subsequent period (P=0.042). In another analysis, we compared the characteristics of the 2groups and concluded that they were homogeneous.

CONCLUSION

The degree of experience is an independent factor for mortality. The application of a care protocol is fundamental to facilitate the management of ECMO therapy.

Vitrification of in vitro produced bovine embryos: in vitro and in vivo evaluations

The efficacy of different vitrification solutions to cryopreserve in vitro produced bovine blastocysts was evaluated based upon in vitro development of embryos in culture and on in vivo development of embryos transferred into recipients. In the first experiment, ethylene glycol + glycerol (Eg + Gly) + different sucrose concentrations were evaluated. There were no significant differences in development rates among solutions. As for hatching, the Eg + Gly + 0.1 M sucrose group had a greater rate as compared with Eg + Gly + 0 M sucrose and Eg + Gly + 0.5 M sucrose groups in the evaluations of Day 6, Day 7 and Day 6 + Day 7 embryos; and, Eg + Gly + 0.3 M sucrose group had a greater rate as compared with the Eg + Gly + 0 M sucrose and Eg + Gly + 0.5 M sucrose groups in evaluations of Day 6 and Day 6 + Day 7 embryos. There were no significant differences in development and hatching rates between Day 6 and 7 in in vitro produced bovine embryos within each treatment group. There were significant differences in nuclei number after vitrification between Eg + Gly + 0.1 M and Eg + Gly + 0 M sucrose groups and the Eg + Gly + 0.5 M sucrose group. Pregnancy after 60 days of transfer and calving rates showed a difference between in vivo produced embryos freshly transferred and in vitro produced embryos vitrified with Eg + Gly + 0.3 M. There were no significant differences in gestation length and sex ratio between treatments. As for birth weight, there were significant differences between fresh in vivo produced embryos and all treatments of in vitro produced embryos. There were significant differences in dystocial parturition between in vivo produced embryos and all treatments with in vitro produced embryos. These results demonstrate that vitrification can be used successfully in the cryopreservation of in vitro produced bovine embryos, and that it might be considered for use in commercial programs.

Pregnancy rates after transfer of frozen bovine embryos: a field trial

An efficient and practical technique for bovine embryo cryopreservation is a fundamental issue in the widespread use of embryo transfer. The present study shows results obtained in field experiments. In the first experiment, two slow-freezing methods using glycerol and a one-step method using ethylene glycol were compared: glycerol added in two steps (5 and then 10%), glycerol added in one step (10%) and 1.5 M ethylene glycol with direct transfer. The three methods were equally effective; pregnancy rates of 40.4, 39.1 and 45.4%, respectively were achieved. In the second experiment, using 1.5 M ethylene glycol with direct transfer, 20 and 5 min of equilibration of the cryoprotectant were tested. There were no observed significant differences in pregnancy rates. In the third experiment, ethylene glycol and propylene glycol were combined with three sucrose concentrations (0, 0.1 or 0.3 M) in a one-step method. It was observed that ethylene glycol and 0.1 M sucrose yielded the highest pregnancy rate, not differing from fresh controls. Similar pregnancy rates were noted after using multiple-step or one-step methods, but the one-step method is preferable due to its simplicity and applicability to field conditions.

Liquid chromatographic profiles of individual compounds of technical toxaphene

The elution orders of 20 hexa- to nonachlorobornanes and five hexa- to octachlorocamphenes were studied with normal-phase silica and amino phase HPLC, reversed-phase HPLC, as well as gel-permeation chromatography (GPC). Twenty-one compounds of technical toxaphene (CTTs) are commercially available and four were isolated from environmental samples. Structure-activity relationships and chromatographic properties were deduced from the data sets derived on these LC systems. The retention on silica (low-resolution LC and HPLC) increased with the polarity of the CTTs. The elution order of CTTs on amino normal-phase HPLC was, for the most part, the same as on silica normal-phase HPLC. The degree of chlorination determined the elution order of CTTs on C18 RP-HPLC. CTTs eluted from medium-pressure GPC with decreasing molecular size. Chlorobornanes with dichloro substituents on the six-membered ring eluted after the chloroboranes without geminal chlorine atoms on secondary carbons, indicating that these congeners are larger. Altogether, the results increase the knowledge of complex substance class and may serve as a tool in order to gain further standard components.

In vitro evaluation and pregnancy rates after vitrification of in vitro produced bovine embryos

The efficacy of different vitrification solutions to cryopreserve in vitro-produced bovine blastocysts was evaluated based on in vitro development of embryos in culture and on in vivo development of embryos transferred into recipients. In the first experiment, 2 vitrification solutions were compared: propylene glycol + glycerol (Pg + Gly) and ethylene glycol + Ficoll + sucrose (EFS). Differences in the overall development and hatching rates in favor of EFS were found (56.4 vs 33.3% and 35.4 vs 13.3%; P < 0.05). In the second experiment, 3 vitrification solutions were compared: EFS, modified EFS (EFSm) and ethylene glycol + glycerol (Eg + Gly). The vitrification solutions EFSm and Eg + Gly yield higher hatching rates than did EFS (57.7 vs 59.6 vs 35.7%; P < 0.05). The last experiment was designed to compare in vivo 2 vitrification solutions: EFSm and Eg + Gly. There were no differences between them based on the results obtained after transfer (35.2 vs 43.7%). The vitrification solutions EFSm and Eg + Gly have resulted in good pregnancy rates. These results demonstrated that vitrification can be used successfully in the cryopreservation of in-vitro produced bovine embryos, and it might be considered for use in commercial programs.

Effect of hyaluronic acid on development of in vitro produced bovine embryos

The present study was carried out to evaluate the effect of hyaluronic acid (HA) added to the culture medium on bovine embryo development to the blastocyst stage as well as embryo quality and viability after freezing and thawing. In vitro matured and fertilized (IVM/IVF) bovine oocytes from slaughterhouse ovaries were cultured for 8 d in SOFm supplemented with 4 mg/mL fatty acid-free BSA, either in the absence or presence of 1 or 0.5 mg/mL HA. There was a significant increase in blastocyst yield in the presence of 1 mg/mL HA (P < 0.01), whereas 0.5 mg/mL HA was ineffective. Cleavage rate and mean number of days to blastocyst formation were unaffected by HA at any concentration. At 1 mg/mL, HA did not affect either post-freeze survival of Grade 1 and 2 blastocysts or the number of nuclei per blastocyst. Supplementation with HA at 1 mg/mL also significantly enhanced embryo development up to the blastocyst stage (P < 0.05) in a chemically-defined culture medium without a protein source. It is concluded that supplementation of both semi-defined and defined culture media with 1 mg/mL HA improves the development of IVM/IVF bovine embryos to the blastocyst stage, without affecting embryo quality and post-freeze survival. These results open the possibility of including HA in culture media in order to increase the efficiency of in vitro blastocyst production from in vitro-matured bovine oocytes.

Cryopreservation of ovine embryos: slow freezing and vitrification

Different methods for the cryopreservation of ovine embryos were evaluated in vitro (survival upon culture in vitro) and in vivo (pregnancy and lambing rates after transfer in field conditions). In the first 2 experiments, slow freezing conditions were evaluated. When glycerol and ethylene glycol were compared, no differences in the overall pregnancy rate were found (40.2 vs 51.3%), but better results were obtained with ethylene glycol than with glycerol in morulae (29.7 vs 59.4%, P < 0.05). In the second experiment, 2 methods of removing ethylene glycol were compared: a 1-step procedure using 0.5-M sucrose and a 3-step process for decreasing ethylene glycol concentration. There were no differences in the overall pregnancy rate (48.0 vs 48.0%) between the 2 methods. The last series of experiments were designed to compare 2 vitrification solutions: propylene glycol--glycerol (PG) and ethylene glycol--Ficoll 70--sucrose (EFS). There were no differences between the 2 vitrification solutions, based on the overall pregnancy rate (28.1 vs 40.0%). The vitrification technique and specially with EFS solution has resulted in good pregnancy rates. The EFS solution was particularly efficacious with morulae (55.5% pregnancy). These results demonstrate that vitrification with EFS can be used successfully for the cryopreservation of ovine embryos.

A large-scale program in laparoscopic intrauterine insemination with frozen-thawed semen in Australian Merino sheep in Argentine Patagonia

This report shows the results of a large-scale laparoscopic intrauterine insemination program on a flock of Australian Merino sheep in Argentine Patagonia. The study was carried out on a total of 1824 ewes (3-to-7-yr-old) and 480 ewe hoggets (19-20 months old) on 2 farms in the southeastern region of Santa Cruz Province, in April and May 1996. The animals, divided into 15 groups, were synchronized with vaginal sponges containing 60 mg medroxyprogesterone acetate for 14 d and injected with 200 IU PMSG upon sponge removal. Estrus was screened every 12 h by means of vasectomized marker rams. The animals were inseminated laparoscopically by the intrauterine route using 2 schemes: 1) at a fixed time (12 h) after estrus detection, or 2) at a fixed time (60 h) after sponge removal irrespective of estrus. Pregnancy was determined at 30 d by transrectal ultrasound imaging. The results showed that 1) the onset of estrus occurs most often between 24 and 48 h after sponge removal, 2) ewe hoggets undergo estrus significantly earlier than sexually mature ewes, 3) in those animals showing estrus, there appears to be no relationship between fertility (as assessed by pregnancy outcome) and time of estrus, 4) there is a significant association between the percentage of estrus occurrence and pregnancy rate, 5) fertility is significantly higher in ewes than in hoggets, 6) for practical purposes insemination at a fixed time after the onset of estrus has no advantage over that of to insemination at a fixed time after sponge removal. It is concluded that large-scale laparoscopic intrauterine insemination can be successfully applied in Australian Merino ewes and ewe hoggets in low-productivity areas such as that of Argentine Patagonia and that estrus detection is unnecessary when insemination is performed at 60 h after sponge removal.