Consistent Phosphenes Generated by Electrical Microstimulation of the Visual Thalamus. An Experimental Approach for Thalamic Visual Neuroprostheses

Most work on visual prostheses has centered on developing retinal or cortical devices. However, when retinal implants are not feasible, neuroprostheses could be implanted in the lateral geniculate nucleus (LGN) of the thalamus, the intermediate relay station of visual information from the retina to the visual cortex (V1). The objective of the present study was to determine the types of artificial stimuli that when delivered to the visual thalamus can generate reliable responses of the cortical neurons similar to those obtained when the eye perceives a visual image. Visual stimuli {Si} were presented to one eye of an experimental animal and both, the thalamic {RThi} and cortical responses {RV1i} to such stimuli were recorded. Electrical patterns {RThi*} resembling {RThi} were then injected into the visual thalamus to obtain cortical responses {RV1i*} similar to {RV1i}. Visually- and electrically generated V1 responses were compared. Results: During the course of this work we: (i) characterized the response of V1 neurons to visual stimuli according to response magnitude, duration, spiking rate, and the distribution of interspike intervals; (ii) experimentally tested the dependence of V1 responses on stimulation parameters such as intensity, frequency, duration, etc., and determined the ranges of these parameters generating the desired cortical activity; (iii) identified similarities between responses of V1 useful to compare the naturally and artificially generated neuronal activity of V1; and (iv) by modifying the stimulation parameters, we generated artificial V1 responses similar to those elicited by visual stimuli. Generation of predictable and consistent phosphenes by means of artificial stimulation of the LGN is important for the feasibility of visual prostheses. Here we proved that electrical stimuli to the LGN can generate V1 neural responses that resemble those elicited by natural visual stimuli

Influencia de la radioterapia sobre la reconstrucción mamaria inmediata posmastectomía ahorradora de piel. ¿Afecta igual antes que después?

Introducción La mastectomía bilateral con reconstrucción inmediata (MB + RMI) está aumentando. La radioterapia incrementa las complicaciones, pero se han ampliado los criterios de administración. Queremos evaluar las tasas de complicaciones/secuelas realizando un análisis comparativo con una cohorte sin radioterapia. Métodos Análisis observacional analítico de cohortes retrospectivo de pacientes tratadas mediante MB como tratamiento de cáncer de mama con RMI entre 2000 y 2016. Se evalúan 3 grupos: grupo 1: pacientes previamente tratadas con cirugía local y radioterapia, y MB + RMI posterior; grupo 2: pacientes con MB + RMI y radioterapia posterior por un cáncer de novo, y grupo 3: pacientes con MB + RMI sin radioterapia previa ni posterior. Evaluamos variables demográficas, técnicas quirúrgicas y morbilidad postoperatoria. Resultados Se intervinieron un total de 296 MB + RMI. Grupo 1: 125 pacientes con radioterapia previa, administrada 21, 69 meses antes de media. Tasa de complicaciones del 28, 8%, secuelas 33, 6% y reintervención 33, 6%. Grupo 2:71 pacientes con radioterapia tras reconstrucción 134, 2 días de media. Tasa de complicaciones del 29, 6%, secuelas 19, 9% y reintervención 16, 9%. Grupo 3: 100 pacientes. Tasa de complicaciones del 30%, secuelas 21% y reintervención 20%. Encontramos más secuelas en el grupo 1, con casi el doble de reintervenciones que en el grupo 2 (33, 6% vs. 16, 9%; p = 0, 067). Conclusiones La tasa de complicaciones a largo plazo y la tasa de reintervenciones es mayor en el grupo MB + RMI con radioterapia previa que en los grupos MB + RMI con radioterapia posterior o MB + RMI sin radioterapia. Introduction: The use of bilateral mastectomy with immediate reconstruction is increasing. Radiotherapy increases complications; however, its uses have been extended. We evaluate the profile of the complications and long-term failure of reconstruction through a comparative analysis with a cohort without radiotherapy. Methods: Retrospective analysis of patients with breast cancer who underwent mastectomy with immediate reconstruction during 2000-2016. Three groups were evaluated: 1) patients who received radiotherapy and posterior breast reconstruction; 2) patients with bilateral mastectomy and immediate reconstruction following adjuvant radiotherapy; 3) patients who did not receive radiotherapy at all. Demographic variables, surgical techniques and postoperative morbidity were assessed. Outcomes and complications were compared between cohorts. Analysis was done with SPSS Statistics. Results: 296 bilateral mastectomies with immediate reconstruction. Mean age 48.4 ± 9. No differences in comorbidity in the different groups. Group 1: 125 patients. Radiotherapy given 21.69 months before, on average. Complication rate: 20%. Failure of reconstruction rate: 20%. Reoperation rate: 33.6%. Group 2: 71 patients. Radiotherapy after reconstruction: mean 134.2 days. Complication rate: 36.7%. Failure of reconstruction rate: 21.1%. Reoperation rate: 16.9%. Group 3: 100 patients. Complication rate: 25%. Failure of reconstruction rate: 21%. Reoperation rate: 20%. Morbidity published in patients after radiotherapy before or after reconstruction is higher than complications in patients who did not receive radiotherapy. Even so, in our series they were similar. We found a higher sequelae rate in group 1, with almost double the rate of reoperation. Conclusions: Patients who underwent radiotherapy before reconstruction had a higher risk of developing failure of reconstruction and needing reoperation than those patients who received radiotherapy after breast reconstruction or did not receive radiotherapy at all

Tourniquet use for civilian extremity hemorrhage: Systematic review of the literature [Uso de torniquete nas hemorragias de extremidades na população civil: Revisão sistemática da literatura]

Introduction: extremity tourniquet (TQ) use has increased in the civilian setting; the beneficial results observed in the military has influenced acceptance by EMS and bystanders. This review aimed to analyze extremity TQ types used in the civilian setting, injury site, indications, and complications. Methods: a systematic review was conducted based on original articles published in PubMed, Embase, and Cochrane following PRISMA guidelines from 2010 to 2019. Data extraction focused on extremity TQ use for hemorrhage control in the civilian setting, demographic data, study type and duration, mechanism of injury, indications for use, injury site, TQ type, TQ time, and complications. Results: of the 1384 articles identified, 14 were selected for review with a total of 3912 civilian victims with extremity hemorrhage and 3522 extremity TQ placements analyzed. The majority of TQs were applied to male (79%) patients, with blunt or penetrating trauma. Among the indications for TQ use were hemorrhagic shock, suspicion of vascular injuries, continued bleeding, and partial or complete traumatic amputations. Upper extremity application was the most common TQ application site (56%), nearly all applied to a single extremity (99%), and only 0, 6% required both upper and lower extremity applications. 80% of the applied TQs were commercial devices, and 20% improvised. Conclusions: TQ use in the civilian setting is associated with trauma-related injuries. Most are single-site TQs applied for the most part to male adults with upper extremity injury. Commercial TQs are more commonly employed, time in an urban setting is under 1 hour, with few complications described. Introdução: o uso de torniquete em extremidades (TQ) aumentou no ambiente civil; os resultados benéficos observados nas forças armadas influenciaram a aceitação por equipes de pré-hospitalar (PH) assim como pela população leiga. Esta revisão teve como objetivo analisar os tipos de TQ de extremidades usados em ambiente civil, local da lesão, indicações e complicações. Métodos: revisão sistemática foi conduzida com base em artigos originais publicados no PubMed, Embase e Cochrane seguindo as diretrizes do PRISMA de 2010 a 2019. Extração de dados focada no uso de TQ de extremidade para controle de hemorragia em ambiente civil, dados demográficos, tipo de estudo e duração, mecanismo de lesão, indicações de uso, local da lesão, tipo de TQ, tempo de TQ e complicações. Resultados: dos 1.384 artigos identificados, 14 foram selecionados para revisão com total de 3.912 vítimas civis com hemorragia nas extremidades e 3.522 colocações de extremidades TQ analisadas. A maioria foi aplicado em pacientes do sexo masculino (79%), com trauma contuso ou penetrante. Entre as indicações estavam choque hemorrágico, suspeita de lesões vasculares, sangramento contínuo e amputações traumáticas parciais ou completas. A aplicação na extremidade superior foi o local de aplicação mais comum (56%), quase todos aplicados a uma única extremidade (99%), e apenas 0, 6% requereram aplicações nas extremidades superior e inferior. 80% dos TQs aplicados eram dispositivos comerciais e 20% improvisados. Conclusões: o uso de TQ em ambientes civis está associado a traumas. Os TQs comerciais são mais utilizados, com tempo menor que uma hora de uso e poucas complicações

Partial diazoxide responsiveness in a neonate with hyperinsulinism due to homozygous ABCC8 mutation

We report a case of partial diazoxide responsiveness in a child with severe congenital hyperinsulinaemic hypoglycaemia (CHI) due to a homozygous ABCC8 mutation. A term baby, with birth weight 3.8 kg, born to consanguineous parents presented on day 1 of life with hypoglycaemia. Hypoglycaemia screen confirmed CHI. Diazoxide was commenced on day 7 due to ongoing elevated glucose requirements (15 mg/kg/min), but despite escalation to a maximum dose (15 mg/kg/day), intravenous (i.v.) glucose requirement remained high (13 mg/kg/min). Genetic testing demonstrated a homozygous ABCC8 splicing mutation (c.2041-1G>C), consistent with a diffuse form of CHI. Diazoxide treatment was therefore stopped and subcutaneous (s.c.) octreotide infusion commenced. Despite this, s.c. glucagon and i.v. glucose were required to prevent hypoglycaemia. A trial of sirolimus and near-total pancreatectomy were considered, however due to the significant morbidity potentially associated with these, a further trial of diazoxide was commenced at 1.5 months of age. At a dose of 10 mg/kg/day of diazoxide and 40 µg/kg/day of octreotide, both i.v. glucose and s.c. glucagon were stopped as normoglycaemia was achieved. CHI due to homozygous ABCC8 mutation poses management difficulties if the somatostatin analogue octreotide is insufficient to prevent hypoglycaemia. Diazoxide unresponsiveness is often thought to be a hallmark of recessively inherited ABCC8 mutations. This patient was initially thought to be non-responsive, but this case highlights that a further trial of diazoxide is warranted, where other available treatments are associated with significant risk of morbidity. Learning points: Homozygous ABCC8 mutations are commonly thought to cause diazoxide non-responsive hyperinsulinaemic hypoglycaemia. This case highlights that partial diazoxide responsiveness in homozygous ABCC8 mutations may be present. Trial of diazoxide treatment in combination with octreotide is warranted prior to considering alternative treatments, such as sirolimus or near-total pancreatectomy, which are associated with more significant side effects

Partial diazoxide responsiveness in a neonate with hyperinsulinism due to homozygous ABCC8 mutation

We report a case of partial diazoxide responsiveness in a child with severe congenital hyperinsulinaemic hypoglycaemia (CHI) due to a homozygous ABCC8 mutation. A term baby, with birth weight 3.8 kg, born to consanguineous parents presented on day 1 of life with hypoglycaemia. Hypoglycaemia screen confirmed CHI. Diazoxide was commenced on day 7 due to ongoing elevated glucose requirements (15 mg/kg/min), but despite escalation to a maximum dose (15 mg/kg/day), intravenous (i.v.) glucose requirement remained high (13 mg/kg/min). Genetic testing demonstrated a homozygous ABCC8 splicing mutation (c.2041-1G>C), consistent with a diffuse form of CHI. Diazoxide treatment was therefore stopped and subcutaneous (s.c.) octreotide infusion commenced. Despite this, s.c. glucagon and i.v. glucose were required to prevent hypoglycaemia. A trial of sirolimus and near-total pancreatectomy were considered, however due to the significant morbidity potentially associated with these, a further trial of diazoxide was commenced at 1.5 months of age. At a dose of 10 mg/kg/day of diazoxide and 40 µg/kg/day of octreotide, both i.v. glucose and s.c. glucagon were stopped as normoglycaemia was achieved. CHI due to homozygous ABCC8 mutation poses management difficulties if the somatostatin analogue octreotide is insufficient to prevent hypoglycaemia. Diazoxide unresponsiveness is often thought to be a hallmark of recessively inherited ABCC8 mutations. This patient was initially thought to be non-responsive, but this case highlights that a further trial of diazoxide is warranted, where other available treatments are associated with significant risk of morbidity. Learning points: Homozygous ABCC8 mutations are commonly thought to cause diazoxide non-responsive hyperinsulinaemic hypoglycaemia. This case highlights that partial diazoxide responsiveness in homozygous ABCC8 mutations may be present. Trial of diazoxide treatment in combination with octreotide is warranted prior to considering alternative treatments, such as sirolimus or near-total pancreatectomy, which are associated with more significant side effects.This article is freely available via Open Access. Click on the Publisher's URL to access the full-text

Diagram versus bundle equivalence for Zt × Z22 -cocyclic Hadamard matrices

One of the most promising structural approaches to resolving the Hadamard Conjecture uses the family of cocyclic matrices over Zt×Z22. Two types of equivalence relations for classifying cocyclic matrices over Zt ×Z22 have been independently found. Any cocyclic matrix equivalent by either of these relations to a Hadamard matrix will also be Hadamard. Bundle equivalence is based on algebraic relations between cocycles over any finite group. Diagram equivalence is based on geometric relations between diagrammatic visualisations of cocyclic matrices over the group Zt ×Z22. Here we reconcile the two. We show the group Bund(t) generated by bundle equivalence operations is isomorphic to a subgroup of index 2 in the group Diag(t) generated by diagram equivalence operations, and that Diag(t) = <Bund(t),T> where T is the geometric translation of matrix transposition