[Perioperative fluid management in major abdominal surgery]

Intravascular fluid administration belongs to the cornerstones of perioperative treatment with a substantial impact on surgical outcome especially with respect to major abdominal surgery. By avoidance of hypovolemia and hypervolemia, adequate perioperative fluid management significantly contributes to the reduction of insufficient tissue perfusion as a determinant of postoperative morbidity and mortality. The effective use of intravascular fluids requires detailed knowledge of the substances as well as measures to guide fluid therapy. Fluid management already starts preoperatively and should be continued in the postoperative setting (recovery room, peripheral ward) considering a patient-adjusted and surgery-adjusted hemodynamic monitoring. Communication between all team members participating in perioperative care is essential to optimize fluid management.

Arthroscopic repair of posterosuperior rotator cuff tears with bioabsorbable patch augmentation: a magnetic resonance-controlled case series with 1-year follow-up

Background

Among many advances in the treatment of rotator cuff tears, arthroscopic augmentation techniques with patches of various biological and synthetic graft materials have been introduced to reinforce the repair. However, structural and functional outcomes after patch augmentation vary, and reinforcing the tendon healing remains a challenge. The aim of this study was to evaluate clinical and radiologic outcomes 1 year after arthroscopic posterosuperior (PS) rotator cuff repair with bioabsorbable patch augmentation.

Methods

From October 2014 to December 2017, all patients with PS rotator cuff tears undergoing arthroscopic repair with patch augmentation using a resorbable, biologically derived poly-4-hydroxybutyrate patch (Biofiber; Wright, Memphis, TN, USA) were enrolled in this study. Only full-thickness PS lesions with ≥1 of the following tear patterns were augmented with a patch and were the subject of this study: large U- and L-shaped tear, transtendinous tear, delamination, and fraying of the bursal layer. Patients were examined preoperatively and at 1 year postoperatively with a standardized examination protocol and magnetic resonance imaging (MRI).

Results

Sixteen patients were included in this study; 1 patient was lost to follow-up. One patient only underwent clinical follow-up. We detected 1 repair failure (6.7%) with dislocation of the lateral-row anchors on computed tomography scanning at 3 months postoperatively. MRI was performed in 14 patients after 1 year; in all of them, the cuff repair was intact. The Sugaya tendon integrity score was 1.7 ± 0.9. The Constant-Murley score improved from 44 to 89 points (P < .001). Muscular strength improved in the supraspinatus (from 2.6 to 4.8), infraspinatus (from 3.2 to 4.9), and subscapularis (from 4 to 4.9) (all P < .001). Overall, patient satisfaction was high (3.6 ± 0.6).

Discussion

This small-sized case series is the first to prospectively assess clinical and radiologic outcomes after patch augmentation of PS rotator cuff tears using bioabsorbable poly-4-hydroxybutyrate patches. Good to excellent structural and functional outcomes were observed with a low retear rate (6.7%) and good tendon integrity on 1-year postoperative MRI, and the graft did not cause any complications. The use of bioabsorbable patches could be beneficial when unfavorable PS tear patterns are encountered in which a stable repair of the full tendon thickness at its insertion is otherwise difficult to reach.

A Tale of Two Valves: Bioprosthetic Aortic Valve Obstruction in Systemic Lupus Erythematosus and Antiphospholipid Antibody Syndrome

Patients with systemic lupus erythematosus (SLE) and antiphospholipid antibody syndrome (APLAS) are at risk for cardiac manifestations, specifically valvular heart disease requiring valve replacement. Bioprosthetic valve endocarditis is an important cause of valve failure, and it is important to keep a wide differential, especially in patients with preexisting SLE and APLAS. In this E-challenge, 2 cases of bioprosthetic aortic valve endocarditis are presented; 1 case describes infective bacterial endocarditis on an aortic prosthesis and the second describes a patient with SLE and APLAS who developed bioprosthetic valve obstruction secondary to vegetations, consistent with nonbacterial endocarditis and thrombus. Etiologies for bioprosthetic valve obstruction and evaluation by echocardiography are explored. The comparison between these 2 cases specifically highlights the importance of keeping a wide differential in endocarditis, prosthetic valve vegetations, and bioprosthetic valve obstruction.

Protective effects of 4-aminopyridine in experimental optic neuritis and multiple sclerosis

Chronic disability in multiple sclerosis is linked to neuroaxonal degeneration. 4-aminopyridine (4-AP) is used and licensed as a symptomatic treatment to ameliorate ambulatory disability in multiple sclerosis. The presumed mode of action is via blockade of axonal voltage gated potassium channels, thereby enhancing conduction in demyelinated axons. In this study, we provide evidence that in addition to those symptomatic effects, 4-AP can prevent neuroaxonal loss in the CNS. Using in vivo optical coherence tomography imaging, visual function testing and histologic assessment, we observed a reduction in retinal neurodegeneration with 4-AP in models of experimental optic neuritis and optic nerve crush. These effects were not related to an anti-inflammatory mode of action or a direct impact on retinal ganglion cells. Rather, histology and in vitro experiments indicated 4-AP stabilization of myelin and oligodendrocyte precursor cells associated with increased nuclear translocation of the nuclear factor of activated T cells. In experimental optic neuritis, 4-AP potentiated the effects of immunomodulatory treatment with fingolimod. As extended release 4-AP is already licensed for symptomatic multiple sclerosis treatment, we performed a retrospective, multicentre optical coherence tomography study to longitudinally compare retinal neurodegeneration between 52 patients on continuous 4-AP therapy and 51 matched controls. In line with the experimental data, during concurrent 4-AP therapy, degeneration of the macular retinal nerve fibre layer was reduced over 2 years. These results indicate disease-modifying effects of 4-AP beyond symptomatic therapy and provide support for the design of a prospective clinical study using visual function and retinal structure as outcome parameters.

Comparison of different optomotor response readouts for visual testing in experimental autoimmune encephalomyelitis-optic neuritis

Optomotor response is increasingly used in preclinical research for evaluating the visual function in rodents. However, the most suitable measuring protocol for specific scientific questions is not always established. We aimed to determine the optimal parameters for visual function analysis in experimental autoimmune encephalomyelitis optic neuritis (EAEON), an animal model for multiple sclerosis. Contrast sensitivity as well as spatial frequency both had a low variance and a good test-retest reliability. Also, both parameters were able to differentiate between the EAEON and the control group. Correlations with the retinal degeneration, assessed by optical coherence tomography, the infiltration of immune cells, and the clinical disability score revealed that spatial frequency was superior to contrast sensitivity analysis. We therefore conclude that spatial frequency testing is better suited as visual acuity assessment in C57Bl/6 J EAEON mice. Furthermore, contrast sensitivity measurements are more time consuming, possibly leading to more stress for the animals.

Efficacy of antiseptics in a novel 3-dimensional human plasma biofilm model (hpBIOM)

The increasing incidence of non-healing wounds constitutes a pivotal socio-economic burden. 60-80% of chronic wounds are colonized by pathogenic microorganisms within a protective extracellular polymeric substance, bearing a great challenge in wound management. Human plasma was used to prepare the biofilm model (hpBIOM), adding pathogens to the plasma and forming Coagula-like discs with integrated pathogens were produced. The antiseptics Octenisept and Lavasorb were tested regarding their antibacterial properties on clinically relevant biofilm-growing bacteria (MRSA, P. aeruginosa) in the hpBIOM. Biofilm-typical glycocalyx-formation was confirmed using immunohistochemical staining. Treatment of a 12 h-maturated biofilm with Octenisept resulted in complete eradication of P. aeruginosa and MRSA after 48 h. Lavasorb proved less effective than Octenisept in this setting. In more mature biofilms (24 h), both antiseptics showed a delayed, partially decreased efficacy. Summarized, the hpBIOM provides essential factors for a translational research approach to be used for detailed human biofilm analyses and evaluation of antimicrobial/-biofilm properties of established and novel therapeutic strategies and products. Octenisept and Lavasorb showed an attenuated efficacy in the hpBIOM compared to planktonic conditions and previously published biofilm-studies, prompting the question for the necessity of introducing new international standards and pre-admission requirements on a translational base.

Monitoring retinal changes with optical coherence tomography predicts neuronal loss in experimental autoimmune encephalomyelitis

Background

Retinal optical coherence tomography (OCT) is a clinical and research tool in multiple sclerosis, where it has shown significant retinal nerve fiber (RNFL) and ganglion cell (RGC) layer thinning, while postmortem studies have reported RGC loss. Although retinal pathology in experimental autoimmune encephalomyelitis (EAE) has been described, comparative OCT studies among EAE models are scarce. Furthermore, the best practices for the implementation of OCT in the EAE lab, especially with afoveate animals like rodents, remain undefined. We aimed to describe the dynamics of retinal injury in different mouse EAE models and outline the optimal experimental conditions, scan protocols, and analysis methods, comparing these to histology to confirm the pathological underpinnings.

Methods

Using spectral-domain OCT, we analyzed the test-retest and the inter-rater reliability of volume, peripapillary, and combined horizontal and vertical line scans. We then monitored the thickness of the retinal layers in different EAE models: in wild-type (WT) C57Bl/6J mice immunized with myelin oligodendrocyte glycoprotein peptide (MOG_35–55) or with bovine myelin basic protein (MBP), in TCR^2D2 mice immunized with MOG_35–55, and in SJL/J mice immunized with myelin proteolipid lipoprotein (PLP_139–151). Strain-matched control mice were sham-immunized. RGC density was counted on retinal flatmounts at the end of each experiment.

Results

Volume scans centered on the optic disc showed the best reliability. Retinal changes during EAE were localized in the inner retinal layers (IRLs, the combination of the RNFL and the ganglion cell plus the inner plexiform layers). In WT, MOG_35–55 EAE, progressive thinning of IRL started rapidly after EAE onset, with 1/3 of total loss occurring during the initial 2 months. IRL thinning was associated with the degree of RGC loss and the severity of EAE. Sham-immunized SJL/J mice showed progressive IRL atrophy, which was accentuated in PLP-immunized mice. MOG_35–55-immunized TCR^2D2 mice showed severe EAE and retinal thinning. MBP immunization led to very mild disease without significant retinopathy.

Conclusions

Retinal neuroaxonal damage develops quickly during EAE. Changes in retinal thickness mirror neuronal loss and clinical severity. Monitoring of the IRL thickness after immunization against MOG_35–55 in C57Bl/6J mice seems the most convenient model to study retinal neurodegeneration in EAE.

Early Operative Versus Nonoperative Treatment of Fragility Fractures of the Pelvis: A Propensity-Matched Multicenter Study

OBJECTIVE

To compare early operative treatment with nonoperative treatment of fragility fractures of the pelvis regarding mortality and functional outcome.

DESIGN

Retrospective.

SETTING

Two trauma centers.

PATIENTS AND METHODS

Two hundred thirty consecutive patients 60 years of age or older with an isolated low-energy fracture of the pelvis and with a follow-up of at least 24 months. In center 1, treatment consisted of a nonoperative attempt and early operative fixation if mobilization was not possible. In center 2, all patients were treated nonoperatively.

MAIN OUTCOME MEASUREMENTS

Primary outcome was mortality. Secondary outcomes were in-hospital complications. Patients who survived were contacted by phone, and a modified Majeed score was obtained to assess functional outcome at the final follow-up.

RESULTS

At the final follow-up (mean 61 months, SD 24), 105/230 (45.7%) patients had died. One year after the initial hospitalization, 34/148 patients [23%, 95% confidence interval (CI): 17%-31%] of the early operative group and 14/82 patients (17%, 95% CI: 10%-27%) of the nonoperative group had died (P = 0.294). Nonoperative treatment had a protective effect on survival during the first 2 years (hazard ratio of the nonlinear effect: 2.86, 95% CI: 1.38-5.94, P < 0.001). Patients in the early operative treatment group who survived the first 2 years had a better long-term survival. The functional outcome at the end of follow-up as measured by a modified Majeed score was not different between the 2 groups (early operative: 66.1, SD 12.6 vs. nonoperative: 65.7, SD 12.5, P = 0.910).

CONCLUSION

Early operative fixation of patients who cannot be mobilized within 3-5 days was associated with a higher mortality rate and complication rate at 1 year but with a better long-term survival after more than 2 years. Hence, patients with a life expectancy of less than 2 years may not benefit from surgery with regard to survival.

LEVEL OF EVIDENCE

Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Early Operative Versus Nonoperative Treatment of Fragility Fractures of the Pelvis: A Propensity-Matched Multicenter Study

OBJECTIVE

To compare early operative treatment with nonoperative treatment of fragility fractures of the pelvis regarding mortality and functional outcome.

DESIGN

Retrospective.

SETTING

Two trauma centers.

PATIENTS AND METHODS

Two hundred thirty consecutive patients 60 years of age or older with an isolated low-energy fracture of the pelvis and with a follow-up of at least 24 months. In center 1, treatment consisted of a nonoperative attempt and early operative fixation if mobilization was not possible. In center 2, all patients were treated nonoperatively.

MAIN OUTCOME MEASUREMENTS

Primary outcome was mortality. Secondary outcomes were in-hospital complications. Patients who survived were contacted by phone, and a modified Majeed score was obtained to assess functional outcome at the final follow-up.

RESULTS

At the final follow-up (mean 61 months, SD 24), 105/230 (45.7%) patients had died. One year after the initial hospitalization, 34/148 patients [23%, 95% confidence interval (CI): 17%-31%] of the early operative group and 14/82 patients (17%, 95% CI: 10%-27%) of the nonoperative group had died (P = 0.294). Nonoperative treatment had a protective effect on survival during the first 2 years (hazard ratio of the nonlinear effect: 2.86, 95% CI: 1.38-5.94, P < 0.001). Patients in the early operative treatment group who survived the first 2 years had a better long-term survival. The functional outcome at the end of follow-up as measured by a modified Majeed score was not different between the 2 groups (early operative: 66.1, SD 12.6 vs. nonoperative: 65.7, SD 12.5, P = 0.910).

CONCLUSION

Early operative fixation of patients who cannot be mobilized within 3-5 days was associated with a higher mortality rate and complication rate at 1 year but with a better long-term survival after more than 2 years. Hence, patients with a life expectancy of less than 2 years may not benefit from surgery with regard to survival.

LEVEL OF EVIDENCE

Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Surgical Treatment of Distal Femur Fractures in Geriatric Patients

Introduction:

The treatment of distal femur fractures in geriatric patients is challenging and has a high perioperative morbidity and mortality. Treatments have evolved significantly in the past decades. The aim of our study was to analyze local and systemic morbidity and mortality, as well as functional results in this frail cohort treated with distal femur locking plates.

Materials and methods:

In this single-institution case series, we retrospectively analyzed the data of patients aged 65 years and older with fractures of the distal femur between March 2013 and March 2018. All patients were operated with distal femur locking plates. Points of interest included perioperative morbidity, mortality, weight-bearing status, and care-dependency after hospital discharge.

Results:

We assessed 49 patients (median age: 86.5 years) with 52 distal femur fractures (AO type A 77%, type C 15%, type B 8%). A total of 30 (58%) periprosthetic fractures with 4 (8%) interimplant femur fractures were documented. The perioperative morbidity was 64%, and the 3-month and 1-year mortality rates were 29% and 35%, respectively. The local complication rate was 6% with no documented implant failure. Of the patients who were living at home before the surgery, 62% required long-term accommodation in residential or nursing homes after dicharge from the hospital or short-term rehabilitation.

Conclusions:

Geriatric patients with distal femur fractures face a high perioperative mortality. Osteosynthesis with distal femur locking plates is a reliable technique that can be used in various fracture patterns including periprosthetic and interimplant fractures.

History of Evolutionary Thought Since 1930

Evolutionary biology underwent several significant transformations in the period after 1930. While mid-century was dominated by the evolutionary synthesis and the professionalization of evolutionary biology, the second half of the 20th century saw evolutionary research diversifying and the domain of evolutionary phenomena expanded, especially in response to the rise of molecular biology. While what happened in 1950 may seem ancient to a contemporary evolutionary biologist, to a historian of biology the last half of the 20th century is recent history. Where the literature on Darwin could fill a bibliography by itself, the history of modern evolutionary biology is neither as extensive nor as comprehensive. Some topics such as the evolutionary synthesis and molecular evolution have a rich historical literature. Others such as cultural evolution or quantitative genetics still await further historical analysis: not because they are undeserving, but because they are just now becoming ripe for historical investigation. For the purposes of this article, we selected significant pieces of historical and some philosophical scholarship that address major developments in the history of evolutionary biology. We did not select so-called classic papers by evolutionary biologists or review papers written by biologists. Instead our focus was on evolutionary biology as it has been contextualized and discussed by historians who have often been seeking to address a range of non-biological issues regarding the nature and practice of science, and how different aspects of evolutionary biology reflect the time and place of their development.