Mechanical efficiency of positive work in running at different speeds

To investigate the possible role of elastic potentiation on mechanical efficiency, three male marathon runners were filmed while running on a treadmill at various steady-state speeds ranging from 7.0-22.0 km X h-1. Kinematic and mechanical energy analyses were performed from the film. Expired air was collected for energy expenditure determination. The analysis disclosed that during contact on the treadmill the knee and ankle joints initially had a phase of negative (flexion) angular velocity, followed by a positive velocity. In the hip joint the stretch-shortening cycle of the extensor muscles occurred primarily during the flight phase. The mean vertical and horizontal forces of the negative and positive phases of the contact period increased linearly with the increase in the running speed. The calculated mechanical efficiency of positive work was high but relatively constant (55.1 +/- 12.7%) across all speeds. The absolute contribution of the extra work, which comes from the stored elastic energy to the positive work, increased with running speed; however, its relative value (0.61 +/- 0.09 J X min-1 X kg-1) remained constant at all measured speeds. It is suggested, therefore, that when the flight phase is included in the mechanical energy calculations, the measured efficiency for the positive work reaches a high but constant value in running at low-to-moderate speeds.     

Multiple pheochromocytomas in a patient with blurred vision

We report on a 19-year-old male diagnosed with multiple pheochromocytomas after an I-123 metaiodobenzylguanidine (MIBG) scan. Multiple imaging was obtained because of concern for von Hippel-Lindau disease (VHL) after bilateral retinal angiomas were discovered on ophthalmologic consultation as a follow-up from the Emergency Department. Computed tomography (CT) and magnetic resonance imaging (MRI) were able to localize the adrenal and extra-adrenal tumors; however, accurate differentiation between pheochromocytomas and other adrenal tumors was not possible. I-123 MIBG is the test of choice for evaluating functionality and location of pheochromocytomas because of its high sensitivity and specificity. I-123 MIBG was performed before surgery to confirm that the lesions were indeed pheochromocytomas and also to rule out metastatic disease. He was started on alpha- and beta-blocker medication for at least 3 weeks, followed by surgery. The postoperative period was uneventful. DNA testing was performed and revealed mutations in the VHL gene previously reported to be associated with von Hippel-Lindau syndrome type II and genetic counseling was recommended. He was presented in urology tumor board conference with recommendations for follow-up CT and laboratory tests after 3 months. Otherwise, the patient is doing well and asymptomatic at this time.     

A simple method to obtain the correct length of the artificial chordae in complex chordal replacement

BACKGROUND: Different techniques have been proposed to measure the correct length of artificial chordae. We herein describe a new simple method to measure the chordal length in complex chordal replacement. METHOD: Chordal replacement was used by us for two different purposes: (1) to maintain the correct chordal length for the anterior leaflet (AL) and (2) to eliminate any movement of the posterior leaflet (PL) to fix it. To reach this goal, the AL is pulled up to the maximum extent and the new chordae are tied 5 mm higher than the related border. On the contrary, in the PL the new chordae are tied at the level of the related border. RESULTS: From March 2006 to March 2007, at the University of Catania, this technique was used in 32 patients (16 for correction of PL prolapse, 6 patients for correction of AL prolapse, and in 10 patients for correction of both leaflets prolapse). The number of chordae per patients was 8.6 for the PL and 6.8 for the AL. No patient died or had major complications. After a mean follow-up of 5 +/- 2 months, two-dimensional echocardiography showed that all the patients had no or trivial mitral regurgitation (MR). The echocardiogram showed a correct movement of the new chordae. CONCLUSIONS: This technique allows to easily establish the length of the new chordae of the AL and, if necessary, of the PL in complex mitral valve repair.     

Molecular determinants of milk lipid secretion

Mammary epithelial cells secrete lipids by an envelopment process that produces lipid droplets coated by membranes derived from the plasma membrane and possibly secretory vesicles. This secretion process, which resembles viral budding, is hypothesized to be mediated by specific interactions between molecules on the surface of intracellular lipids and membrane elements of the cell. Multiple lines of evidence indicate that milk lipid secretion occurs through a tripartite complex between the integral transmembrane protein, butyrophilin (BTN); the soluble metabolic enzyme, xanthine oxidoreductase (XOR); and the lipid droplet surface protein, adipophilin (ADPH). However, topological evidence from freeze-fracture replica immunolabelling (FRIL) challenge this model and suggests that milk lipid secretion is mediated by butyrophilin alone. Advances in our understanding of the molecular, structural, and functional properties of these proteins now make it possible to understand the physiological functions of each of these molecules in detail and to identify the specific molecular determinants that mediate milk lipid secretion.     

Delayed wound healing in Mac-1–deficient mice is associated with normal monocyte recruitment

The Mac-1 integrin is an important mediator of migration and inflammatory activation of neutrophils and monocytes. However, the role of Mac-1 in modulating macrophage emigration and activation and its subsequent impact on cutaneous wound healing have not been fully elucidated. To examine the significance of Mac-1 to murine wound healing, we measured epithelialization and granulation tissue formation in partial-thickness ear wounds and full-thickness head wounds, respectively, in Mac-1-deficient mice. Wounds were histologically analyzed at postwounding days 3, 5, and 7. The gap measured between the leading edges of inward-migrating granulation tissue was significantly increased in knockout mice compared with control animals at day 5 (3.8+/-0.3 vs. 2.6+/-0.5 mm; p<0.001) and day 7 (2.2+/-0.4 vs. 0.96+/-0.73 mm; p=0.005). Epithelial gap measurements were also increased in knockout mice vs. wild-type controls at days 3 (0.62+/-0.02 vs. 0.54+/-0.07 mm; p<0.05) and 5 (0.58+/-0.06 vs. 0.39+/-0.08 mm; p<0.001). Immunohistochemistry showed equal numbers of macrophages in knockout and control wounds. These findings show that Mac-1 is required for normal wound healing but that the attenuation in the deposition of granulation tissue and wound epithelialization in Mac-1 knockout mice is not associated with decreased monocyte migration into the wound.     

Esophegeal replacement in children with AIDS

We report 2 human immunodeficiency virus-positive patients with refractory esophageal strictures secondary to candidiasis. They presented with progressive dysphagia and had suffered from oropharyngeal and/or esophageal candidiasis within the preceding 3 months. Both failed conservative management of these strictures, including systemic antifungal therapy, administration of proton pump inhibitors, and numerous attempts at stricture dilation, ultimately progressing to open transhiatal esophagectomy. Although challenging in the immunocompromised host, successful treatment of these strictures by gastric interposition is achievable with minimal morbidity.     

Anogenital HIV RNA in Thai men who have sex with men in Bangkok during acute HIV infection and after randomization to standard vs. intensified antiretroviral regimens

Introduction

HIV transmission risk is highest during acute HIV infection (AHI). We evaluated HIV RNA in the anogenital compartment in men who have sex with men (MSM) during AHI and compared time to undetectable HIV RNA after three-drug versus five-drug antiretroviral therapy (ART) to understand risk for onward HIV transmission.

Methods

MSM with AHI (n=54) had blood, seminal plasma and anal lavage collected for HIV RNA at baseline, days 3 and 7, and weeks 2, 4, 12 and 24. Data were compared between AHI stages: 1 (fourth-generation antigen-antibody combo immunoassay [IA]–, third-generation IA–, n=15), 2 (fourth-generation IA+, third-generation IA–, n=9) and 3 (fourth-generation IA+, third-generation IA+, western blot–/indeterminate, n=30) by randomization to five-drug (tenofovir+emtricitabine+efavirenz+raltegravir+maraviroc, n=18) versus three-drug (tenofovir+emtricitabine+efavirenz, n=18) regimens.

Results

Mean age was 29 years and mean duration since HIV exposure was 15.4 days. Mean baseline HIV RNA was 5.5 in blood, 3.9 in seminal plasma and 2.6 log₁₀ copies/ml in anal lavage (p<0.001). Blood and seminal plasma HIV RNA were higher in AHI Stage 3 compared to Stage 1 (p<0.01). Median time from ART initiation to HIV RNA <50 copies/ml was 60 days in blood, 15 days in seminal plasma and three days in anal lavage. Compared with the three-drug ART, the five-drug ART had a shorter time to HIV RNA <1500 copies/ml in blood (15 vs. 29 days, p=0.005) and <50 copies/ml in seminal plasma (13 vs. 24 days, p=0.048).

Conclusions

Among MSM with AHI, HIV RNA was highest in blood, followed by seminal plasma and anal lavage. ART rapidly reduced HIV RNA in all compartments, with regimen intensified by raltegravir and maraviroc showing faster HIV RNA reductions in blood and seminal plasma.     

Incomplete Administration of Intravenous Vancomycin Prophylaxis is Common and Associated With Increased Infectious Complications After Primary Total Hip and Knee Arthroplasty

BackgroundVancomycin is often used as antimicrobial prophylaxis in patients undergoing total hip or knee arthroplasty. Vancomycin requires longer infusion times to avoid associated side effects. We hypothesized that vancomycin infusion is often started too late and that delayed infusion may predispose patients to increased rates of surgical site infections and prosthetic joint infections.MethodsWe reviewed clinical data for all primary total hip arthroplasty (THA) and total knee arthroplasty (TKA) patients at our institution between 2013 and 2020 who received intravenous vancomycin as primary perioperative gram-positive antibiotic prophylaxis. We calculated duration of infusion before incision or tourniquet inflation, with a cutoff of 30 minutes defining adequate administration. Patients were divided into two groups: 1) appropriate administration and 2) incomplete administration. Surgical factors and quality outcomes were compared between groups.ResultsWe reviewed 1047 primary THA and TKA patients (524 THAs and 523 TKAs). The indication for intravenous vancomycin usage was allergy (61%), methicillin-resistant staphylococcus aureus colonization (17%), both allergy and colonization (14%), and other (8%). 50.4% of patients began infusion >30 minutes preoperatively (group A), and 49.6% began infusion <30 minutes preoperatively (group B). Group B had significantly higher rates of readmissions for infectious causes (3.6 vs 1.3%, P = .017). This included a statistically significant increase in confirmed prosthetic joint infections (2.2% vs 0.6%, P = .023). Regression analysis confirmed <30 minutes of vancomycin infusion as an independent risk factor for PJI when controlling for comorbidities (OR 5.22, P = .012).ConclusionLate infusion of vancomycin is common and associated with increased rates of infectious causes for readmission and PJI. Preoperative protocols should be created to ensure appropriate vancomycin administration when indicated.     

Urgent desensitization in patients bridged to heart transplantation under extracorporeal membrane oxygenation support: A preliminary experience

Antihuman leukocyte antigen (HLA) antibodies restrict the access to cardiac allografts. Desensitization therapy is a major challenge in patients with cardiogenic shock waiting for urgent heart transplantation (HT). We retrospectively reviewed six patients (mean age of 37.5 years [16–70]) who underwent plasmapheresis (PP) under extracorporeal membrane oxygenation (ECMO) before transplant between January 2017 and September 2018. The average duration of follow‐up was 25 months [20–32]. Mean fluorescence intensity (MFI) of HLA‐specific antibodies was reported as follows: score 4 for MFI < 1000, score 6 for 1000 < MFI < 3000 and score 8 for MFI > 3000. The mean duration of ECMO support was 29 days [1–74] and 6.8 [1–29] PP sessions were performed per patient before transplant. The mean number of HLA‐specific antibodies before HT was 9.6 for score 6 [4–13] and 5.8 for score 8 [1–12]. Four patients had major complications after transplantation (2 hemorrhagic shocks, 5 infectious events). Mean MFI reduction rate was 94% [79–100] for Class I and 44.2% for Class II [0–83]. Hospital survival was 100%, and early antibody‐mediated rejection was diagnosed in one patient at 7 days after HT. Plasmapheresis under ECMO support was associated with favorable early outcomes in highly sensitized candidates for urgent heart transplantation.     

Combined Pancreatic Islet–Lung Transplantation: A Novel Approach to the Treatment of End‐Stage Cystic Fibrosis

Patients with end‐stage cystic fibrosis (CF) and severe CF‐related diabetes (CFRD) may benefit from combined lung‐pancreatic islet transplantation. In the present study, we report the long‐term follow‐up of four end‐stage CF patients treated with combined bilateral lung and pancreatic islet transplantation from the same donor. All patients were C‐peptide negative (<0.5 μg/L) and inadequately controlled despite intensive insulin treatment. One patient was transplanted with 4 019 ± 490 islet equivalent/kg injected into the transverse colic vein using a surgical approach. In the remaining three patients, islets were cultured for 3–6 days and transplanted by percutaneous transhepatic catheterization of the portal vein. In all patients, islet allograft recovery was recognized by elevation in the plasma level of C‐peptide (>0.5 μg/L). At 6 months after transplantation, one patient showed multiple episodes of acute lung transplant rejection and a progressive decline in pancreatic islet cell function. Three out of four patients experienced an improved control of glucose levels with a HbA1c of 5.2%, 7% and 6% respectively at 1.5, 2 and 15 years follow‐up. Compared with the pretransplant period, there was a 50% reduction in mean daily insulin needs. Pulmonary function remained satisfactory in all patients. In conclusion, our cases series shows that combined bilateral lung and pancreatic islet transplantation may be a viable therapeutic option for patients with end‐stage CF and CFRD.