The impact of a night float system on operative experience in neurosurgery residency

OBJECTIVE

Since the Accreditation Council for Graduate Medical Education (ACGME) implemented duty-hour restrictions in 2003, many residency programs have adopted a night float system to comply with time constraints. However, some surgical subspecialities have been concerned that use of a night float system deprives residents of operative experience. In this study, the authors describe their training program's transition to a night float system and its impact on resident operative experience.

METHODS

The authors conducted a single-program study of resident surgical case volume before and after implementing the night float system at 3 of their 5 hospitals from 2014 to 2020. The authors obtained surgical case numbers from the ACGME case log database.

RESULTS

Junior residents received a concentrated educational experience, whereas senior residents saw a significant decrease from 112 calls/year to 17. Logged cases significantly increased after implementation of the night float system (8846 vs 10,547, p = 0.04), whereas cases at non-night float hospitals remained the same. This increase was concurrent with an increase in hospital cases. This difference was mainly driven by senior resident cases (p = 0.010), as junior and chief residents did not show significant differences in logged cases (p > 0.40). Lead resident cases increased significantly after implementation of the night float system (6852 vs 8860, p = 0.04). When normalized for increased hospital cases, resident case increases were not statistically significant.

CONCLUSIONS

Transitioning to a night float call system at the authors' institution increased overall resident operative cases, particularly for lead resident surgeons. Based on the results of this study, the authors recommend the use of a night float call system to consolidate night calls, which increases junior resident-level educational opportunities and senior resident cases.

[Management of the first nonfebrile seizure in infants and children]

Seizures are the most common pediatric neurologic disorder. This article describes the guidelines of the French Pediatric Neurology Society, highlighting the importance of a thorough history and examination. Paroxysmal nonepileptic events should be excluded. The role of biological and neuroradiological investigations is discussed. An electroencephalographic recording and advice from a pediatric neurologist are suggested.

Residual Oil Saturation Inside the Steam Chamber During SAGD

Abstract

The oil saturation inside the steam chamber during steamassisted gravity drainage (SAGD) has an important impact on economics and conservation. However, the SAGD residual oil saturation is difficult to determine and model because it involves long-term thermal effects and three-phase flow. SAGD has been widely studied and piloted, but improved understanding of longterm drainage effects represents a fundamental issue that requires improved understanding.

In the first part of the paper, we represent a sensitivity test done on the shapes and the endpoints of the two-phase relative permeability curves. We find that the water relative permeability and oil relative permeability in the gas-oil system are the main factors that determine the magnitude and shape of the oil saturation curve as a function of time.

Secondly, we demonstrate how to adjust the krog relative permeability curve to match a theoretically determined residual oil saturation, which is supported by laboratory data. We propose that, during SAGD, the flow of oil can be split into two regimes. In the first regime, close to the edge of the steam chamber, oil drains quickly in a short period of time. In the second regime, oil drains slowly within the steam chamber for a longer period of time, as it is produced by "film drainage." To capture these flow regimes, the oil relative permeability curve in the gas-oil system, krog, is split into two. At higher liquid saturations, the first flow regime is represented and, at lower liquid saturations, the second regime is modelled.

Thirdly, the krog curve was adjusted so that the decrease in oil saturation with respect to time closely matched the theoretical curve while maintaining oil production rates expected for SAGD. Using this new curve at different pressures, we show that the residual oil saturation increases at lower SAGD operating pressures.

Introduction

In a steam-assisted gravity drainage (SAGD) process, bitumen drainage occurs mainly along the transition zone, which is the mobile liquid region at the boundary of the steam chamber. Bitumen drainage also continues to occur within the body of the steam chamber over a long period of time, such that the residual oil saturation gradually falls.

In this paper, the term residual oil saturation refers to the average remaining oil saturation within the steam chamber where the steam chamber includes all grid blocks in a numerical model containing any amount of steam. It is difficult to obtain residual oil saturation data as a function of time in the field so, in this study, we relied on theoretical and laboratory data. We calibrated reservoir simulation results to the theoretical and laboratory data, and then used the simulator to investigate the effects of SAGD operating pressures on the residual oil saturation.

Relative Permeability Formulation

Multiphase flow in a porous medium can be described using Darcy's Law as follows:

Identification and characterisation of a developmentally regulated mammalian gene that utilises -1 programmed ribosomal frameshifting

Translational recoding of mRNA through a -1 ribosomal slippage mechanism has been observed in RNA viruses and retrotransposons of both eukaryotes and prokaryotes. Whilst this provides a potentially powerful mechanism of gene regulation, the utilization of -1 translational frameshifting in regulating mammalian gene expression has remained obscure. Here we report a mammalian gene, Edr, which provides the first example of -1 translational recoding in a eukaryotic cellular gene. In addition to bearing functional frameshift elements that mediate expression of distinct polypeptides, Edr bears both CCHC zinc-finger and putative aspartyl protease catalytic site retroviral-like motifs, indicative of a relic retroviral-like origin for Edr. These features, coupled with conservation of Edr as a single copy gene in mouse and man and striking spatio-temporal regulation of expression during embryogenesis, suggest that Edr plays a functionally important role in mammalian development.

A juxtamembrane autophosphorylation site in the Eph family receptor tyrosine kinase, Sek, mediates high affinity interaction with p59fyn

The large subfamily of receptor tyrosine kinases (RTKs) for which EPH is the prototype have likely roles in intercellular communication during normal mammalian development, but the biochemical signalling pathways utilised by this family are poorly characterised. We have now identified two in vitro autophosphorylation sites within the juxtamembrane domain of the Eph family member Sek, and a candidate binding protein for the activated Sek kinase. Specific antibodies defined Sek as a 130 kDa glycoprotein with protein kinase activity expressed in keratinocytes, whilst a bacterially expressed gst-Sek kinase domain fusion protein autophosphorylated exclusively on tyrosine residues, confirming that Sek encodes an authentic protein tyrosine kinase. Two dimensional phosphopeptide mapping and site-directed mutagenesis defined juxtamembrane residue Y602 as a major site of in vitro autophosphorylation in Sek, whilst Y596 was phosphorylated to a lower stoichiometry. Complimentary approaches of in vitro binding assays and BIAcore analysis revealed a high affinity association between the Y602 Sek autophosphorylation site and the cytoplasmic tyrosine kinase p59fyn, an interaction mediated through the SH2 domain of this intracellular signalling molecule. Moreover, these data identify the novel phosphotyrosyl motif pYEDP as mediating high affinity association with fyn-SH2, extending the previously defined consensus motif for this interaction. The extensive conservation of this fyn-binding motif within the juxtamembrane domain of Eph family RTKs suggests that signalling through fyn, or fyn-related, tyrosine kinases may be utilised by many members of this large subclass of transmembrane receptors.

Cloning and developmental expression of Nsk2, a novel receptor tyrosine kinase implicated in skeletal myogenesis

The protein superfamily of transmembrane receptor tyrosine kinases (RTKs) are essential components of intercellular signalling pathways necessary for normal cellular regulation. We report the cloning and developmental expression pattern of Nsk2, a novel, structurally distinct mammalian RTK characterised by a putative extracellular region bearing four immunoglobulin-like domains. The Nsk2 locus was mapped to the distal region of mouse chromosome 13 and was found to be expressed preferentially in skeletal muscle amongst adult mouse tissues. Moreover, increased steady-state levels of Nsk2 transcripts were apparent on terminal differentiation of committed skeletal myoblast cell lines in vitro and multiple isoforms of the Nsk2 RTK were identified in skeletal myotube cultures. RNA in situ hybridisation studies of mouse embryos confirmed skeletal myogenesis to be a major site of Nsk2 expression during normal embryogenesis, and identified other likely sites of Nsk2 function in ganglia of the developing peripheral nervous system and various embryonic epithelia, including those of kidney, lung and gut, during fetal development. Taken together, our data suggest normal functions for Nsk2 RTKs in distinctive aspects of skeletal muscle development, neurogenesis and mesenchymal-epithelial interactions during organ formation.

Hot Springs waters and the treatment of venereal diseases: the U.S. Public Health Service Clinic and Camp Garraday

Hot Springs, Arkansas and healing have been almost synonymous since the Indians lived in the area. From the end of World War I until the early 1940s, venereal disease patients flocked to Hot Springs for treatment. The primary focus of this paper is to tell the story of the facilities built to provide treatment. The government at both the federal, state, and local levels had to accommodate the great demand for treatment. The U.S. Public Health Service Clinic and Camp Garraday at Hot Springs were two major facilities built to meet that demand. Almost forgotten today, these two establishments afforded many patients the opportunity for healing unavailable in local situations. The Clinic provided the best treatment available and performed needed research studies on venereal disease during its peak years.

The Public Health Service VD clinic in Hot Springs, AR

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