Detection of microspheres in vivo using multispectral optoacoustic tomography

We introduce a new approach to detect individual microparticles that contain NIR fluorescent dye by multispectral optoacoustic tomography in the context of the hemoglobin-rich environment within murine liver. We encapsulated a near infrared (NIR) fluorescent dye within polystyrene microspheres, then injected them into the ileocolic vein, which drains to the liver. NIR absorption was determined using multispectral optoacoustic tomography. To quantitate the minimum diameter of microspheres, we used both colorimetric and spatial information to segment the regions in which the microspheres appear. Regional diameter was estimated by doubling the maximum regional distance. We found that the minimum microsphere size threshold for detection by multispectral optoacoustic tomography images is 78.9 µm.     

Pretracheal abscess following two weeks of endotracheal intubation

Pretracheal abscess due to endotracheal intubation has not been reported in literature. We present a case of a female patient who was admitted with acute hypercapnic respiratory failure. Patient was initially managed with noninvasive ventilation but eventually was intubated after sustaining a cardiac arrest. She could not be extubated because of poor weaning parameters, so a tracheostomy was planned. During surgery, a pretracheal abscess was found with destruction of the second, third, and fourth tracheal rings and intact posterior tracheal wall. The possible risk factors, mechanism of injury, and preventive strategy of tracheal complication of intubation are discussed.     

Extracorporeal photopheresis (photochemotherapy) in the treatment of acute and chronic graft versus host disease: immunological mechanisms and the results from clinical studies

Extracorporeal photopheresis (ECP) is an immunomodulatory alternative for treatment of graft versus host disease (GVHD). The blood is then separated into its various components through apheresis; buffy coat cells are thereafter treated with 8-methoxypsoralen before exposure to ultraviolet light and finally reinfused into the patient. There is a general agreement that this treatment has an anti-GVHD effect, but the mechanisms of action behind this effect are only partly understood. However, altered maturation of dendritic cells (DC) and thereby indirect modulation of T-cell reactivity seems to be one important mechanism together with DC-presentation of antigens derived from apoptotic donor T cells and induction of regulatory T cells. The treatment has been best studied in patients with chronic GVHD (both pediatric and adult patients), but most studies are not randomized and it is difficult to know whether the treatment is more effective than the alternatives. The clinical studies of ECP in adults with acute GVHD are few and not randomized; it is not possible to judge whether this treatment should be a preferred second- or third-line treatment. There is no evidence for increased risk of leukemia relapse or suppression of specific graft versus leukemia reactivity by this treatment, so specific antileukemic immunotherapy may still be possible. Thus, even though the treatment seems effective in patients with GVHD, further clinical (especially randomized) as well as biological studies with careful standardization of the treatment are needed before it is possible to conclude how ECP should be used in acute and chronic GVHD.     

Isoform switching facilitates period control in the Neurospora crassa circadian clock

A striking and defining feature of circadian clocks is the small variation in period over a physiological range of temperatures. This is referred to as temperature compensation, although recent work has suggested that the variation observed is a specific, adaptive control of period. Moreover, given that many biological rate constants have a Q₁₀ of around 2, it is remarkable that such clocks remain rhythmic under significant temperature changes. We introduce a new mathematical model for the Neurospora crassa circadian network incorporating experimental work showing that temperature alters the balance of translation between a short and long form of the FREQUENCY (FRQ) protein. This is used to discuss period control and functionality for the Neurospora system. The model reproduces a broad range of key experimental data on temperature dependence and rhythmicity, both in wild‐type and mutant strains. We present a simple mechanism utilising the presence of the FRQ isoforms (isoform switching) by which period control could have evolved, and argue that this regulatory structure may also increase the temperature range where the clock is robustly rhythmic.     

Seasonal variation in condition, growth and food habits of walleye in a Great Plains reservoir and simulated effects of an altered thermal regime

Catch rates in gillnets and relative weight ( W _r) of walleye Stizostedion vitreum , in Glen Elder Reservoir, Kansas, were lowest during the summer (June–August) and highest during the autumn (September–November). Approximately 80% of their annual growth in length and mass was attained during late summer and autumn. Growth was minimal during winter (January–February) and spring (March–May). The number of walleye with empty stomachs was highest during the summer. Invertebrates (Cladocera, Chironomidae) were common in walleye stomachs during the summer and spring, but contributed little to the ingested biomass. Gizzard shad Dorosoma cepedianum dominated walleye diets (per cent by mass) throughout the year. A bioenergetics model predicted that the proportion of maximum consumption ( P _c) was highest during the autumn and was probably due to spatial overlap of walleye and gizzard shad once water temperatures were <22° C. The bioenergetics model predicted that walleye would lose up to 65% of their body mass during the summer if water temperature increased by 10% (as predicted by some global warming models). Growth during the autumn, winter and spring was enhanced up to 150% by increased temperatures. The results of this study indicate that lower condition, reduced consumption and slow growth are a generalized response of walleye to extreme temperatures. Elevated temperatures may have a net positive effect on walleye growth if they can survive the high thermal stress during summer.     

Mapping the Anatomy of Respiratory Syncytial Virus Infection of the Upper Airways in Chinchillas (Chinchilla lanigera)

Although most viral infections of the upper respiratory tract can predispose to bacterial otitis media, human respiratory syncytial virus (HRSV) is the predominant viral copathogen of this highly prevalent pediatric polymicrobial disease. Rigorous study of the specific mechanisms by which HRSV predisposes to otitis media has been hindered by lack of a relevant animal model. We recently reported that the chinchilla, the preferred rodent host for studying otitis media, is semipermissive for upper-airway HRSV infection. In the current study, we defined the anatomy and kinetics of HRSV infection and spread in the upper airway of chinchilla hosts. Chinchillas were challenged intranasally with a fluorescent-protein–expressing HRSV. Upper-airway tissues were recovered at multiple time points after viral challenge and examined by confocal microscopy and immunohistochemistry. HRSV replication was observed from the rostral- to caudalmost regions of the nasal cavity as well as throughout the Eustachian tube in a time-dependent manner. Although fluorescence was not observed and virus was not detected in nasopharyngeal lavage fluids 14 d after infection, the latest time point examined in this study, occasional clusters of immunopositive cells were present, suggesting that the nasal cavity may serve as a reservoir for HRSV. These data provide important new information concerning the time course of HRSV infection of the uppermost airway and suggest that chinchillas may be useful for modeling the HRSV-induced changes that predispose to secondary bacterial infection.Abbreviations: HRSV, human respiratory syncytial virus; rrHRSV, recombinant red fluorescent human respiratory syncytial virus; URT, upper respiratory tractHuman respiratory syncytial virus (HRSV), an enveloped, negative-strand, nonsegmented RNA virus of the family Paramyxoviridae, is the single greatest causative agent of acute respiratory tract infections in infants and children worldwide.²³ Although HRSV infection generally is limited to the upper respiratory tract (URT), in the United States, primary HRSV infection is associated with a 0.5% hospitalization rate for those children who develop severe bronchiolitis or pneumonia.⁹ One of the most interesting aspects of HRSV is its ubiquity: there are annual winter–spring outbreaks in temperate climates,⁵ and approximately 90% of all children have experienced infection by their second birthday.⁹ Although immunity to HRSV is sufficient to prevent reinfection of the lower airway in most human patients, this response is incomplete, resulting in reinfection of the upper airway throughout life.⁹ Although URT infection by HRSV alone does not constitute a serious problem for healthy adults, its association with the development of bacterial otitis media in children^{11-13,17-19,21,25,28,29,34} and exacerbation of asthma in all age groups¹⁶ make it an important health concern.Despite the ubiquity of the virus, the epidemiology of HRSV is not well understood. There is no known animal reservoir, and although new strains emerge over time, many remain in circulation over several seasons or reappear many years after they were first detected.^27,33 Therefore, although antigenic variation driven by development of HRSV immunity in a given population is possible, this hypothesis has not yet been proven. In fact, in one study,¹⁰ human subjects could be infected repeatedly with the same HRSV strain, and the presence of virus-specific antibody provided only short-lived and incomplete protection. Therefore, HRSV may circulate among seropositive persons, and it has been suggested that persistently infected persons may harbor the virus between seasonal outbreaks.^30,32 Therefore, in addition to the important clinical issues surrounding the prevention of HRSV disease, basic scientific questions regarding HRSV circulation and mechanisms of viral immunoevasion remain unanswered.A key hurdle in the study of HRSV pathogenesis has been the lack of a suitable animal model. Most published studies have used BALB/c mice, which have the advantage of many reagents available for the study of immune responses but the disadvantage of relative resistance to HRSV infection.²² Although pulmonary infection is easily detected in HRSV-infected mice, primary infection of the upper airway in this species is minimal^6,7 and secondary infection of the URT does not occur. More susceptible rodent species include the cotton rat (Sigmidon hispidus)²⁶ and chinchilla (Chinchilla lanigera),⁶ which are both relatively permissive for HRSV infection of the upper airway. Given the paucity of URT specimens encountered in general pathology practice, the development of a robust small animal model for the study of HRSV infection and spread in the uppermost airway is particularly important. Moreover, effective vaccine development depends on a better understanding of why this compartment remains susceptible to reinfection in immune hosts.Here we describe the anatomy of HRSV infection in the chinchilla URT over a 2-wk period, using confocal microscopy to monitor the retrograde spread of a recombinant red fluorescent protein-expressing HRSV construct (rrHRSV)⁸ from the site of inoculation. Although rrHRSV has previously been used to study the susceptibility of various cell types to virus infection in vitro,^8,36 our current report is the first wherein this biologic agent has been used to trace the route and extent of infection after intranasal instillation of virus in vivo. To establish the usefulness of our approach, immunohistochemistry and plaque assay were used to verify the sensitivity and specificity of fluorescence detected at 2, 3, 5, and 14 d after infection. By these combined methods, we were able to follow the retrograde spread of virus infection from the respiratory epithelium of the nasoturbinates and nasopharynx (at the earliest time point) to the Eustachian tubes and ethmoid turbinates at later time points. The ability to visualize the anatomy and kinetics of HRSV replication in the uppermost airway can now form the basis for future studies of upper-airway susceptibility to virus reinfection and bacterial coinfection.