Effectiveness of dry hydrogen peroxide in reducing air and surface bioburden in a multicenter clinical setting.

OBJECTIVE: To determine the effectiveness of dry hydrogen peroxide (DHP) in reducing environmental bioburden in occupied areas. DESIGN: Prospective environmental cohort study. SETTING: The study was conducted in 2 tertiary-care hospitals and 1 free-standing emergency department. INTERVENTION: Environmental air and surface sites were cultured before and after continuous deployment of DHP systems in targeted hospital areas. METHODS: In total, 1,554 surface and 1,036 air samples were collected from 74 patient areas among the 3 facilities on 3 consecutive days before DHP deployment and on days 14, 30, 60, and 90 after deployment. At each sampling time, 2 air samples were collected at each facility from 1 room without DHP, along with 2 outdoor samples from each facility. The impact of negative-pressure usage on the efficacy of DHP was also evaluated, with 1 hospital continuously using negative pressure, another utilizing it only in patient isolation scenarios, and another without negative pressure. RESULTS: In the 2 facilities without continuous negative pressure, exposure to DHP was associated with a significant reduction in surface bioburden, characterized as total colony-forming units (P = .019; P = .002). Significant associations between DHP exposure and reductions in airborne bacterial load at the 2 hospitals were observed (P ≤ .001; P = .041), and the free-standing emergency department experienced a reduction that did not achieve statistical significance (P = .073). CONCLUSIONS: Our findings confirm that DHP has the potential to reduce microbial air and surface bioburden in occupied patient rooms with standard ventilation parameters.

PERINATAL CENTRILOBULAR HEPATIC NECROSIS IN GIANT PANDAS (AILUROPODA MELANOLEUCA): A RETROSPECTIVE STUDY.

Between 1983 and 2012, six giant panda cubs (Ailuropoda melanoleuca) born at a zoological institution were stillborn or died between the ages of 3 and 200 h. Two of the six cubs had panhepatic centrilobular hepatic necrosis (CHN), granulocytic extramedullary hematopoiesis (GEM), positive liver culture for Staphylococcus species, and terminal liver failure. Another low-weight cub was administered oxygen therapy immediately after birth and developed hyaline membranes in air spaces and hepatic necrosis restricted to the hilar region. A retrospective analysis of liver and lung lesions, pulmonary microanatomy, blood-gas barrier ultrastructure, and hepatic myofibroblast proliferation was conducted on the six cubs. Neonates with CHN had concurrent severe periportal GEM accompanied by severe myofibroblast proliferation. The pulmonary blood-gas barrier was markedly increased in one cub with CHN. Developmentally, the lungs of all but one cub were at the late saccular stage, and the lowest-weight cub was in early saccular stage, consistent with immaturity, and had pneumonia comparable to neonatal respiratory distress syndrome (RDS). Stage of lung development was eliminated as the primary factor leading to CHN. The pathogenesis of CHN in these neonates is proposed to be transformation of hepatic stellate cells to myofibroblasts initiating blockage and microvascular constriction of hepatic sinusoids, resulting in insufficient perfusion and cellular hypoxia of hepatocytes surrounding central veins in acinar zone 3.

Directional infrasound sensing using acoustic metamaterials.

Natural and anthropogenic infrasound may travel vast distances, making it an invaluable resource for monitoring phenomena such as nuclear explosions, volcanic eruptions, severe storms, and many others. Typically, these waves are captured using pressure sensors, which cannot encode the direction of arrival-critical information when the source location is not known beforehand. Obtaining this information therefore requires arrays of sensors with apertures ranging from tens of meters to kilometers depending on the wavelengths of interest. This is often impractical in locations that lack the necessary real estate (urban areas, rugged regions, or remote islands); in any case, it requires multiple power, digitizer, and telemetry deployments. Here, the theoretical basis behind a compact infrasound direction of arrival sensor based on the acoustic metamaterials is presented. This sensor occupies a footprint that is orders of magnitude smaller than the span of a typical infrasound array. The diminutive size of the unit greatly expands the locations where it can be deployed. The sensor design is described, its ability to determine the direction of arrival is evaluated, and further avenues of study are suggested.

Nonlocal elastic metasurfaces: Enabling broadband wave control via intentional nonlocality.

While elastic metasurfaces offer a remarkable and very effective approach to the subwavelength control of stress waves, their use in practical applications is severely hindered by intrinsically narrow band performance. In applications to electromagnetic and photonic metamaterials, some success in extending the operating dynamic range was obtained by using nonlocality. However, while electronic properties in natural materials can show significant nonlocal effects, even at the macroscales, in mechanics, nonlocality is a higher-order effect that becomes appreciable only at the microscales. This study introduces the concept of intentional nonlocality as a fundamental mechanism to design passive elastic metasurfaces capable of an exceptionally broadband operating range. The nonlocal behavior is achieved by exploiting nonlocal forces, conceptually akin to long-range interactions in nonlocal material microstructures, between subsets of resonant unit cells forming the metasurface. These long-range forces are obtained via carefully crafted flexible elements, whose specific geometry and local dynamics are designed to create remarkably complex transfer functions between multiple units. The resulting nonlocal coupling forces enable achieving phase-gradient profiles that are functions of the wavenumber of the incident wave. The identification of relevant design parameters and the assessment of their impact on performance are explored via a combination of semianalytical and numerical models. The nonlocal metasurface concept is tested, both numerically and experimentally, by embedding a total-internal-reflection design in a thin-plate waveguide. Results confirm the feasibility of the intentionally nonlocal design concept and its ability to achieve a fully passive and broadband wave control.

BATRACHOCHYTRIUM DENDROBATIDIS IN A CAPTIVE COLLECTION OF GREEN SALAMANDERS ( ANEIDES AENEUS), LONG-TAILED SALAMANDERS ( EURYCEA LONGICAUDA), AND TWO-LINED SALAMANDERS ( EURYCEA BISLINEATA).

A chytridiomycosis outbreak from Batrachochytrium dendrobatidis ( Bd) in a mixed-species plethodontid salamander exhibit resulted in four green salamander ( Aneides aeneus) deaths. One green salamander died before treatment, and three died during treatment with daily 0.005% itraconazole baths. All salamanders had evidence of severe Bd infections via cytology, histopathology, and/or polymerase chain reaction (PCR) at the time of death. Ten long-tailed salamanders ( Eurycea longicauda) and one two-lined salamander ( Eurycea bislineata) that shared the enclosure were initially negative for Bd on quantitative PCR but were prophylactically treated with daily 0.01% itraconazole baths for 11 days. Posttreatment testing yielded eight long-tailed salamanders and one two-lined salamander positive for Bd with low gene equivalents. All salamanders were negative after two to three treatment courses, and there were no additional mortalities. The difference in mortality and fungal load suggested that genus Aneides salamanders may be more susceptible to Bd than genus Eurycea salamanders.

CALCINOSIS CIRCUMSCRIPTA IN A COHORT OF RELATED JUVENILE AFRICAN LIONS (PANTHERA LEO).

Three juvenile, genetically related African lions (Panthera leo) were evaluated for discrete dome-shaped subcutaneous masses present over the proximal lateral metatarsal-tarsal area. The lesions measured 3-8 cm in diameter, were fluctuant to firm, nonulcerated, and attached to underlying structures. On radiographic evaluation, the lesions were characterized by well-circumscribed punctate mineralizations in the soft tissue surrounded by soft tissue swelling without evidence of adjacent bony involvement. On cut surface, the lesions were made of numerous loculi containing 2-5-mm round-to-ovoid, white-to-gray, firm structures interspersed with fibrous tissue and pockets of serosanguinous fluid. Hematology, serum biochemistry, serum thyroid screening (including total thyroxine, total triiodothyronine, free thyroxine, and free triiodothyronine), and serum vitamin D panels (including parathyroid hormone, ionized calcium, and 25-hydroxyvitamin D) were unremarkable. Histopathologic evaluation of the lesions was consistent with calcinosis circumscripta with fibroplasia, chronic inflammation, and seroma formation. An additional two genetically related lions were considered suspect for calcinosis circumscripta based on presentation, exam findings, and similarity to the confirmed cases. All masses self-regressed and were not associated with additional clinical signs other than initial lameness in two cases.

GASTRIC DILATATION VOLVULUS IN ADULT MANED WOLVES (CHRYSOCYON BRACHYURUS).

Gastric dilatation volvulus (GDV) was identified in six adult maned wolves ( Chrysocyon brachyurus ) housed at the Smithsonian Conservation Biology Institute in Front Royal, Virginia, and the Dickerson Park Zoo in Springfield, Missouri. Four individuals were found dead in their enclosures, and GDV was diagnosed postmortem based on radiographic and necropsy findings. Two individuals were diagnosed with GDV antemortem, with one wolf surviving following surgical intervention and supportive management. A concurrent splenic torsion was identified in three of six cases. Although GDV has been well documented in domestic dogs and is known to occur in maned wolves, objective, detailed case descriptions have been limited in this species. This report represents the first description of a surviving case of GDV in the maned wolf. Thorough species-specific documentation of any acutely fatal condition, such as GDV, is imperative for proper case recognition and medical management, with profound implications for species recovery efforts.

FATAL GASTRIC DILATION IN TWO ADULT BLACK-FOOTED FERRETS (MUSTELA NIGRIPES).

Acute gastric dilation resulting in death was identified in two adult black-footed ferrets (Mustela nigripes) housed at the Smithsonian Conservation Biology Institute in Front Royal, Virginia. Both individuals were adult males (3 and 5 yr) and previously clinically healthy prior to the event. The etiology of gastric dilation in both cases could not be definitively determined, and necropsy revealed severe cardiovascular compromise secondary to bloat. Limited literature is available regarding a syndrome of this type in adult black-footed ferrets. Differential diagnoses considered included gastric dilatation volvulus (GDV), severe gastric distention of unknown origin, and gastric outflow obstruction. Given the severity of this syndrome and the findings in these two cases, acute gastric dilation should be considered in black-footed ferrets presenting with acute abdominal distention, respiratory distress, and cardiovascular compromise.

Solitary Osteochondroma in a Ring-Tailed Lemur (Lemur catta).

A 20-y-old, male, ring-tailed lemur (Lemur catta) presented with a large, firm mass on the proximal caudolateral left femur. The animal displayed no clinical signs associated with the mass. Radiographs revealed a mineralized mass protruding from the femur, with an intact femoral cortex. Histopathology diagnosed osteochondroma in view of the presence of a peripheral layer of cartilage with progressive endochondral ossification and typical remodeling of bony trabeculae. The mass grew quickly after the initial biopsy, and a second surgery to debulk 95% of the tumor was performed. Histopathologic features of the larger samples were similar to those of the initial biopsies, with the cartilage layer being discontinuous and development of bone from some borders progressing directly from a periost-like layer. Nineteen months after the second surgery, the mass had regrown and extended further proximally on the femur toward the epiphysis, but the animal remained asymptomatic, and additional debulking was not attempted. This report is the first description of an osteochondroma in a prosimian and describes unique behavior of the tumor compared with osteochondromas found in humans, dogs, and cats.

Hepatocellular carcinoma in captive slender tailed meerkats (Suricata suricatta): 5 cases.

Hepatocellular carcinoma was diagnosed in five slender tailed meerkats (Suricata suricatta) housed at the Smithsonian Institution's National Zoological Park between 1980 and 2013. Animals included four females and one male, ranging from 7 to 15 yr of age. Common clinical signs included weight loss and lethargy. Three of the neoplasms originated from the right medial liver lobe and were located adjacent to or partially incorporated in the gall bladder. Three animals had solitary masses, and two animals had multiple hepatic masses; all were characterized by polygonal to round neoplastic hepatocytes arranged in a trabecular pattern with smaller regions of varied solid, adenoid, and rarely peliod cell patterns. Hemorrhage and necrosis often with cystic degeneration was noted in all five cases. There was no evidence of metastatic disease in any of the cases examined.

Large Scale Parameter Estimation Problems in Frequency-Domain Elastodynamics Using an Error in Constitutive Equation Functional.

This paper presents the formulation and implementation of an Error in Constitutive Equations (ECE) method suitable for large-scale inverse identification of linear elastic material properties in the context of steady-state elastodynamics. In ECE-based methods, the inverse problem is postulated as an optimization problem in which the cost functional measures the discrepancy in the constitutive equations that connect kinematically admissible strains and dynamically admissible stresses. Furthermore, in a more recent modality of this methodology introduced by Feissel and Allix (2007), referred to as the Modified ECE (MECE), the measured data is incorporated into the formulation as a quadratic penalty term. We show that a simple and efficient continuation scheme for the penalty term, suggested by the theory of quadratic penalty methods, can significantly accelerate the convergence of the MECE algorithm. Furthermore, a (block) successive over-relaxation (SOR) technique is introduced, enabling the use of existing parallel finite element codes with minimal modification to solve the coupled system of equations that arises from the optimality conditions in MECE methods. Our numerical results demonstrate that the proposed methodology can successfully reconstruct the spatial distribution of elastic material parameters from partial and noisy measurements in as few as ten iterations in a 2D example and fifty in a 3D example. We show (through numerical experiments) that the proposed continuation scheme can improve the rate of convergence of MECE methods by at least an order of magnitude versus the alternative of using a fixed penalty parameter. Furthermore, the proposed block SOR strategy coupled with existing parallel solvers produces a computationally efficient MECE method that can be used for large scale materials identification problems, as demonstrated on a 3D example involving about 400,000 unknown moduli. Finally, our numerical results suggest that the proposed MECE approach can be significantly faster than the conventional approach of L(2) minimization using quasi-Newton methods.

Paratuberculosis in a mandrill (Papio sphinx).

A 2.5-year-old captive female mandrill (Papio sphinx) died following a protracted course of intermittent abdominal bloat, diarrhea, and severe weight loss. Necropsy revealed emaciation and marked gastrointestinal distention with gas and ingesta. Histologic evaluation revealed severe diffuse granulomatous enterocolitis and mesenteric lymphadenitis with massive numbers of 1-2-microm acid-fast bacilli within macrophages. Additionally, there was moderate to severe multifocal myocardial and vascular amyloidosis, moderate multifocal pyogranulomatous interstitial pneumonia with no acid-fast bacteria, and moderate multifocal glossal candidiasis. Samples of feces, ileum, and colon were positive for Mycobacterium avium subsp. paratuberculosis by radiometric culture and a polymerase chain reaction-amplified DNA probe specific for the insertion sequence IS900 of this organism.