Morphometric study of the scapular free flap and the free rib osteomyocutaneous flap

The scapula free flap is often the first choice for reconstruction of bony defects of the facial skeleton. However, the vascularised rib as part of a free rib osteomyocutaneous flap may be a suitable second choice. We have investigated the morphology and clinical dimensions of the 7th rib and the scapula, and the ability of the available bone to carry dental implants. The age and sex of the cadaver, and the donor side, were also recorded. The dimensions of the scapulas and 7th ribs (n = 130 of each) from 65 cadavers were measured at 4 different points using osteometric methods. Examination showed that bone from the scapula and 7th rib were sufficient for placement of implants. The 7th rib gave reliable measurements for both height and width, and a consistent relation between compact and cancellous bone. Although the scapula provided adequate compact and cancellous bone, there were variations depending on the segment of bone chosen. Bones from male cadavers were more suitable for implantation. In both the scapula and the 7th rib ageing had a significant adverse effect in only one dimension. Most points of measurement have satisfactory bony dimensions for insertion of dental implants.     

Deep neural models for color classification and color constancy

Color constancy is our ability to perceive constant colors across varying illuminations. Here, we trained deep neural networks to be color constant and evaluated their performance with varying cues. Inputs to the networks consisted of two-dimensional images of simulated cone excitations derived from three-dimensional (3D) rendered scenes of 2,115 different 3D shapes, with spectral reflectances of 1,600 different Munsell chips, illuminated under 278 different natural illuminations. The models were trained to classify the reflectance of the objects. Testing was done with four new illuminations with equally spaced CIEL*a*b* chromaticities, two along the daylight locus and two orthogonal to it. High levels of color constancy were achieved with different deep neural networks, and constancy was higher along the daylight locus. When gradually removing cues from the scene, constancy decreased. Both ResNets and classical ConvNets of varying degrees of complexity performed well. However, DeepCC, our simplest sequential convolutional network, represented colors along the three color dimensions of human color vision, while ResNets showed a more complex representation.     

Free Zinc as a Predictive Marker for COVID-19 Mortality Risk

Free zinc is considered to be the exchangeable and biological active form of zinc in serum, and is discussed to be a suitable biomarker for alterations in body zinc homeostasis and related diseases. Given that coronavirus disease 2019 (COVID-19) is characterized by a marked decrease in total serum zinc, and clinical data indicate that zinc status impacts the susceptibility and severity of the infection, we hypothesized that free zinc in serum might be altered in response to SARS-CoV-2 infection and may reflect disease severity. To test this hypothesis, free zinc concentrations in serum samples of survivors and nonsurvivors of COVID-19 were analyzed by fluorometric microassay. Similar to the reported total serum zinc deficit measured by total reflection X-ray fluorescence, free serum zinc in COVID-19 patients was considerably lower than that in control subjects, and surviving patients displayed significantly higher levels of free zinc than those of nonsurvivors (mean ± SD; 0.4 ± 0.2 nM vs. 0.2 ± 0.1 nM; p = 0.0004). In contrast to recovering total zinc concentrations (r = 0.706, p < 0.001) or the declining copper–zinc ratio (r = −0.646; p < 0.001), free zinc concentrations remained unaltered with time in COVID-19 nonsurvivors. Free serum zinc concentrations were particularly low in male as compared to female patients (mean ± SD; 0.4 ± 0.2 nM vs. 0.2 ± 0.1 nM; p = 0.0003). This is of particular interest, as the male sex is described as a risk factor for severe COVID-19. Overall, results indicate that depressed free serum zinc levels are associated with increased risk of death in COVID-19, suggesting that free zinc may serve as a novel prognostic marker for the severity and course of COVID-19.     

The Impact of COVID-19 on Routine Medical Care and Cancer Screening

BackgroundCOVID-19 restrictions and fear dramatically changed the use of medical care. Understanding the magnitude of cancelled and postponed appointments and associated factors can help identify approaches to mitigate unmet need.ObjectiveTo determine the proportion of medical visits cancelled or postponed and for whom. We hypothesized that adults with serious medical conditions and those with higher anxiety, depressive symptoms, and avoidance-oriented coping would have more cancellations/postponements.DesignFour nationally representative cross-sectional surveys conducted online in May, July, October, and December 2020.Participants59,747 US adults who completed 15-min online surveys. 69% cooperation rate.MeasuresPhysical and mental health visits and cancer screening cancelled or postponed over prior 2 months. Plan to cancel or postpone visits over the next 2 months. Relationship with demographics, medical conditions, local COVID-19 death rate, anxiety, depressive symptoms, coping, intolerance of uncertainty, and perceived COVID-19 risk.Key ResultsOf the 58% (N = 34,868) with a medical appointment during the 2 months before the survey, 64% had an appointment cancelled or postponed in May, decreasing to 37% in December. Of the 41% of respondents with scheduled cancer screening, 20% cancelled/postponed, which was stable May to December. People with more medical conditions were more likely to cancel or postpone medical visits (OR 1.19 per condition, 95% CI 1.16, 1.22) and cancer screening (OR 1.20, 95% CI 1.15, 1.24). Race, ethnicity, and income had weak associations with cancelled/postponed visits, local death rate was unrelated, but anxiety and depressive symptoms were strongly related to cancellations, and this grew between May and December.ConclusionsCancelled medical care and cancer screening were more common among persons with medical conditions, anxiety and depression, even after accounting for COVID-19 deaths. Outreach and support to ensure that patients are not avoiding needed care due to anxiety, depression and inaccurate perceptions of risk will be important.Supplementary InformationThe online version contains supplementary material available at 10.1007/s11606-021-07254-x.KEY WORDS: COVID-19, missed medical appointments, cancer screening     

Assessment of Left Ventricular Viscoelastic Components Based on Ventricular Harmonic Behavior

Background: Assessment of left ventricular (LV) function with an emphasis on contractility has been a challenge in cardiac mechanics during the recent decades. The LV function is usually described by the LV pressure-volume (P-V) relationship. Based on this relationship, the ratio of instantaneous pressure to instantaneous volume is an index for LV chamber stiffness. The standard P-V diagrams are easy to interpret but difficult to obtain and require invasive instrumentation for measuring the corresponding volume and pressure data. In the present study, we introduce a technique that can estimate viscoelastic properties, not only the elastic component but also the viscous properties of the LV based on oscillatory behavior of the ventricular chamber and it can be applied non-invasively as well. Materials and Methods: The estimation technique is based on modeling the actual long axis displacement of the mitral annulus plane toward the cardiac base as a linear damped oscillator with time-varying coefficients. Elastic deformations resulting from the changes in the ventricular mechanical properties of myocardium are represented as a time-varying spring while the viscous components of the model include a time-varying viscous damper, representing relaxation and the frictional energy loss. To measure the left ventricular axial displacement ten healthy sheep underwent left thoracotomy and sonomicrometry transducers were implanted at the apex and base of the LV. The time-varying parameters of the model were estimated by a standard Recursive Linear Least Squares (RLLS) technique. Results: LV stiffness at end-systole and end-diastole was in the range of 61.86–136 dyne/g.cm and 1.25–21.02 dyne/g.cm, respectively. Univariate linear regression was performed to verify the agreement between the estimated parameters, and the measured values of stiffness. The averaged magnitude of the stiffness and damping coefficients during a complete cardiac cycle were estimated as 58.63±12.8 dyne/g.cm and 0 dyne.s/g.cm, respectively. Conclusion: The results for the estimated elastic coefficients are consistent with the ones obtained from force-displacement diagram. The trend of change in the estimated parameters is also in harmony with the previous studies done using P-V diagram. The only input used in this model is the long axis displacement of the annulus plane, which can also be obtained non-invasively using tissue Doppler or MR imaging.     

Mid-diaphyseal fibular fractures with syndesmotic disruption: should we plate the fibula?

BACKGROUND: The treatment of mid-diaphyseal fibula fractures with syndesmotic disruption is controversial. The purpose of this study was to compare the biomechanical properties of 2 fixation constructs. MATERIALS AND METHODS: Eight pairs of human cadaveric legs were divided into two groups, both of which had midshaft fibular osteotomies and disruption of all ligamentous support up to the osteotomy level. In Group I, the left legs were fixed with only a 3.5-mm tricortical syndesmotic screw. In Group II, the right legs received this syndesmotic fixation in addition to plating of the fibula. Rotational stability was tested on each ankle in the intact, repaired, and post-cyclical load conditions. Each specimen was ultimately tested to failure in external rotation. RESULTS: The rotational stability, load to failure, and stiffness were all found to be significantly higher with the plate and syndesmotic fixation repair technique (Group II) than with the syndesmotic fixation only technique (Group I). Furthermore, fixation in Group II improved rotational stability both before and after cyclic loading. CONCLUSION: Improved biomechanical properties were found with fibular plating in addition to a syndesmotic screw in a midshaft fibular fracture model with syndesmotic and deltoid injury. CLINICAL RELEVANCE: This information may be helpful in the decision-making process to optimally treat patients with this fracture pattern.     

Peak bone mass of Iranian population: the Iranian Multicenter Osteoporosis Study.

Osteoporosis is a major public health problem in the Western countries and is projected to have a similar impact in the Middle East. It has been suggested that peak bone mineral density (BMD), a major determinant of osteoporotic fractures later in life, may be lower in this part of the world compared with the Western world. The purpose of the Iranian Multicenter Osteoporosis Study was to determine peak bone mass in a randomly chosen sample of healthy Iranian subjects. A total of 5201 participants (2340 males, mean age 42.7+/-13.8) were recruited based on randomized clustered sampling from all regions of five major cities across the country. In women, peak lumbar BMD (1.182+/-0.127 g/cm2) occurred in the 29- to 33-yr age group, whereas peak total femur BMD (1.006+/-0.126 g/cm2) occurred in the 32- to 36-yr age group. In men, peak lumbar BMD (1.181+/-0.153 g/cm2) and femoral BMD (1.096+/-0.159 g/cm2) both occurred in the 20- to 24-yr age group. When standardized to mg/cm2 units using established formulas, Iranian peak bone mass values are comparable with that of Western countries and are generally higher than that of Eastern Asian and Middle Eastern countries.     

Urine macrophage migration inhibitory factor (MIF) in children with urinary tract infection: a possible predictor of acute pyelonephritis

Macrophage migration inhibitory factor (MIF) is an important pro-inflammatory cytokine expressed at sites of inflammation. We have assessed this factor (MIF) in urinary tract infections with the aim of determining a non-invasive and sensitive method to differentiate upper and lower renal involvement. Thirty-three pediatric patients with urinary track infection (25 with acute pyelonephritis, eight with acute cystitis) and 40 healthy subjects were recruited for this prospective case-control study. Pyelonephritis was differentiated from cystitis by dimercaptosuccinic acid (DMSA) scan. Urinary MIF concentration was determined using an enzyme-linked immunosorbent assay method. The urine MIF/creatinine (Cr) ratio was significantly higher in pyelonephritis patients than in those with acute cystitis and the control group (P < 0.001). The optimal cut-point of 4.90 pg/micromol Cr for the urine MIF/Cr ratio has the potential to be a biomarker for distinguishing patients with acute pyelonephritis from those with acute cystitis. Determination of the urinary MIF was also useful in selecting the patients at risk of permanent renal damage. Of those patients with pyelonephritis, based on the DMSA scan at the time of infection, scarring on follow-up DMSA scan 9-12 months later occurred in patients with the highest urinary MIF/Cr ratios. We conclude that the urine MIF/Cr ratio is a sensitive test for differentiating acute pyelonephritis from acute cystitis and also for detecting children with acute pyelonephritis who are at a higher risk for permanent renal scars in the future.