Evaluation of respiratory system models based on parameter estimates from impulse oscillometry data

Impulse oscillometry offers advantages over spirometry because it requires minimal patient cooperation, it yields pulmonary function data in a form that is readily amenable to engineering analysis. In particular, the data can be used to obtain parameter estimates for electric circuit-based models of the respiratory system, which in turn may assist the detection and diagnosis of various diseases/pathologies. Of the six models analyzed during this study, Mead's model seems to provide the most robust and accurate parameter estimates for our data set of 5 subjects with airflow obstruction including asthma and chronic obstructive pulmonary disease and another 5 normal subjects with no identifiable respiratory disease. Such a diagnostic approach, relying on estimated parameter values from a respiratory system model estimate and the degree of their deviation from the normal range, may require additional measures to ensure proper identification of diseases/pathologies but the preliminary results are promising.

Th17 alloimmunity prevents neonatal establishment of lymphoid chimerism in IL-4-deprived mice

Immune responses in newborn mice are known to be biased toward the helper type 2 phenotype. This may account for their propensity to develop tolerance. Herein, we evaluated the effects of IL-4 deprivation on CD4(+) T-cell activities elicited by neonatal exposure to allogeneic spleen cells. We showed that chimerism, Th2-type polarization and pathology, as well as skin allograft acceptance were inhibited in BALB/c mice immunized at birth with (A/J x BALB/c) F(1) spleen cells upon in vivo IL-4 neutralization. While IL-4 neutralization inhibited the development of Th2 cells in this model, it led to the accumulation of IL-17A, IL-17F, IL-22, IL-6 and RORγt mRNA in the spleen or graft tissues. Moreover, IL-4 deprivation led to the differentiation of donor-specific Th17 cells with a concomitant Th1 response characterized by IFN-γ production. The Th17-type response emerging in IL-4-deprived mice was found to mediate both intragraft neutrophil infiltration and the abrogation of B-cell chimerism. Neutralization of this Th17 response failed however to restore functional skin graft acceptance. Collectively, our observations indicate that the neonatal Th2 response opposes the development of Th17 cells, and that Th17 cells are responsible for controlling lymphoid chimerism in mice neonatally injected with semiallogeneic cells.

Blastomycosis of the skull base

Blastomycosis is usually considered a pulmonary or cutaneous disease. A patient with blastomycosis of the infratemporal fossa temporal bone and sinuses without pulmonary disease is presented. Extensive skull base involvement required surgical debridement for relief of pain, and long-term systemic antifungal therapy. The literature is reviewed and discussed.

Physical inactivity, neurological disability, and cardiorespiratory fitness in multiple sclerosis

OBJECTIVE

We examined the associations among physical activity, neurological disability, and cardiorespiratory fitness in two studies of individuals with multiple sclerosis (MS).

METHOD

Study 1 included 25 women with relapsing-remitting MS (RRMS) who undertook an incremental exercise test for measuring peak oxygen (VO₂(peak) ) consumption, wore an accelerometer during a 7-day period, and completed the Godin Leisure-Time Exercise Questionnaire (GLTEQ). Study 2 was a follow-up of Study 1 and included 24 women with RRMS who completed the self-reported Expanded Disability Status Scale (EDSS), undertook an incremental exercise test, wore an accelerometer during a 7-day period, and completed the GLTEQ.

RESULTS

Study 1 indicated that VO₂(peak) was significantly correlated with accelerometer counts (pr = 0.69) and GLTEQ scores (pr = 0.63) even after controlling for age and MS duration. Study 2 indicated that VO₂(peak) was significantly correlated with accelerometer counts (pr = 0.50), GLTEQ scores (pr = 0.59), and EDSS scores (pr = -0.43) even after controlling for age and MS duration; there was a moderate partial correlation between accelerometer counts and EDSS scores (pr = -0.43). Multiple linear regression analysis indicated that both accelerometer counts (β = 0.32) and EDSS scores (β = -0.40) had statistically significant associations with VO₂(peak).

CONCLUSION

The findings indicate that physical inactivity and neurological disability might represent independent risk factors for reduced levels of cardiorespiratory fitness in this population.

Expansion of regulatory CD8+ CD25+ T cells after neonatal alloimmunization

Transplantation tolerance induced by neonatal injection of semi-allogeneic spleen cells is associated with a pathological syndrome caused by T helper type 2 (Th2) differentiation of donor-specific CD4(+) T lymphocytes. We have shown previously that this Th2-biased response is inhibited by host CD8(+) T cells. Herein, we demonstrate that upon neonatal immunization with (A/J × BALB/c)F(1) spleen cells, BALB/c mice expand a population of CD8(+) T cells expressing both CD25 and forkhead box P3 (FoxP3) markers. In this setting, CD8(+) CD25(+) T cells predominantly produce interferon (IFN)-γ and interleukin (IL)-10 and are efficient in controlling IL-4, IL-5 and IL-13 production by donor-specific CD4(+) T cells in vitro. CD8(+) FoxP3(-) T cells are single producers of IFN-γ or IL-10, whereas CD8(+) FoxP3(+) T cells are double producers of IFN-γ and IL-10. We further demonstrate that IFN-γ and IL-10 are two major cytokines produced by CD8(+) T cells involved in the in vivo regulation of Th2-type pathology. In this setting, we conclude that neonatal alloimmunization induces the expansion of several regulatory CD8(+) T cells which may control Th2 activities via IFN-γ and IL-10.

A comparison of linear respiratory system models based on parameter estimates from PRN forced oscillation data

The forced oscillation technique offers some advantages over spirometry for assessing pulmonary function. It requires only passive patient cooperation; it also provides data in a form, frequency-dependent impedance, which is very amenable to engineering analysis. In particular, the data can be used to obtain parameter estimates for electric circuit-based models of the respiratory system, which can in turn aid the detection and diagnosis of various diseases/pathologies. In this study, we compare the least-squares error performance of the RIC, extended RIC, augmented RIC, augmented RIC+I(p), DuBois, Nagels and Mead models in fitting 3 sets of impedance data. These data were obtained by pseudorandom noise forced oscillation of healthy subjects, mild asthmatics and more severe asthmatics. We found that the aRIC+I(p) and DuBois models yielded the lowest fitting errors (for the healthy subjects group and the 2 asthmatic patient groups, respectively) without also producing unphysiologically large component estimates.

A study of IOS data using the aRIC+I(p) model of respiratory impedance

Development of better methods to assess human lung function has been continuing since the existing standard lung function test of spirometry requires subjects to inhale and exhale with maximum effort, which may be troublesome especially for the elderly and young children, leading to unreliable results. Therefore, the method of forced oscillation, and the Impulse Oscillometry System (IOS) in particular, has been developed to lessen the effort of the patients while obtaining valid measurements. The applied pressure waves and the resulting airflow responses are recorded to provide information about the respiratory system's input impedance, which can be fit by electric circuit models to possibly serve as a means to detect and diagnose respiratory diseases. Presently, research continues to find a more accurate model that also provides reasonable component values. This paper proposes the augmented RIC+I(p)(aRIC+I(p)) model and compares it to five other well-known models (the RIC, extended RIC, augmented RIC, DuBois and Mead models) in fitting the IOS data from adult COPD patients and healthy subjects. While the aRIC+I(p) model yielded slightly higher fitting error than the Mead and DuBois models, it did not produce unphysiologically large values for any of its components, unlike the Mead and DuBois models. Hence, the aRIC+(p) model appears to be the most reasonable one for use, at this point in time, in studying IOS-based computer-aided detection and diagnosis of COPD.

Understanding non-disclosure of deferrable risk: a study of blood donors with a history of intravenous drug use

Non-disclosure of deferrable risk has received little attention in the literature. We examined deferrable risk (history of intravenous drug use [IVDU]) and donor attitudes towards truthfulness, the screening process and interpretation of the screening question as well as risk profile. Donors negative for all markers with a self-reported history of IVDU (N = 30) and matched controls were identified from an anonymous mail-out survey. In a separate survey, hepatitis C virus (HCV)-positive donors participated in a telephone interview, from which all those with IVDU history (N = 29) were selected plus matched controls (combined total 59 IVDU, 236 controls). IVDU donors, when compared with matched controls, tended to believe that it is OK not to answer truthfully if one believes that her/his blood is safe (18.6% vs. 4.7%) and that some questions are a little too personal (35.6% vs. 21.7%). IVDU donors were more likely than controls to say they failed to acknowledge screening questions appropriately (23% vs. 2.2%) or to agree that IVDU questions are mainly about recent drug taking or sharing needles (29% vs. 11%) even though the screening question asked about IVDU ever without any such qualifiers. IVDU donors were also more likely to have other lifestyle/risk factors such as history of sex with IVDU (45.5% vs. 1.7%). Donors with deferrable IVDU history may rationalise that revealing their status is not necessary and may misinterpret the question. Failure to acknowledge risk behaviour is complex, and some degree of non-disclosure may be an inherent part of pre-donation screening.

Evaluation of the confidential unit exclusion form: the Canadian Blood Services experience

BACKGROUND

In the mid-1980s, confidential unit exclusion (CUE) was implemented to permit donors unwilling to admit risk factors in screening to exclude their donation from transfusion. With changes in donor behaviour, epidemiology of disease and improvements in testing, many blood establishments have stopped using it. We evaluated its benefit in Canada, and reported its utility in predicting transmissible-disease (TD) and high-risk behaviour.

STUDY DESIGN AND METHODS

TD-positive donations and incident cases between 2004 and 2008 were analyzed in CUE-safe and CUE-unsafe designated donations. An anonymous survey of 40,000 donors asked about CUE use and risk factors.

RESULTS

There were 7104 (0.15%) donations designated CUE-unsafe of 4,775,044 donations. Most TD-positive donations were designated CUE-safe (1023/1030, 99.32%) with only seven (0.68%) designated CUE-unsafe. Of 95 incident cases, all were designated CUE-safe including three NAT-yield cases (1 HIV and 2 HCV). In the survey, some donors found the CUE difficult to understand [10.5% (first-time), 3.2% (repeat)], only half thought that the blood would still be tested [48.9% (first-time), 45.9% (repeat)], and about a fifth believed that collection site staff could see their designation. No survey respondents who used the CUE admitted to risk behaviour, but about 1% of donors who designated CUE-safe had high-risk behaviours.

CONCLUSION

The data do not provide any indication of a safety benefit from CUE, but CUE use results in a small but constant loss of apparently safe donations.

Bulging fontanelle in febrile infants: is lumbar puncture mandatory?

OBJECTIVE

To determine the aetiologies and clinical characteristics of infants with fever and a bulging fontanelle.

DESIGN

The medical records of all febrile infants with a bulging fontanelle who underwent a lumbar puncture from January 2000 to February 2008 in Assaf Harofeh Medical Center, a university affiliated hospital in central Israel, were identified.

RESULTS

153 patients met the inclusion criteria. The male to female ratio was 100:53; age range was 3-11 months with a mean age of 5.6 (SD 1.8) months and a median age of 5 months. Cerebrospinal fluid pleocytosis was found in 42 cases (27.3%), including one case of bacterial meningitis (0.6%). Other leading diagnoses were aseptic meningitis (26.7%), upper respiratory tract infection (18.3%), viral disease not otherwise specified (15.6%), roseola infantum (8.5%) and acute otitis media (6.5%). Appearance on admission was described as good to excellent in 113 (73.8%) infants, none of whom had bacterial meningitis. 32 had aseptic meningitis and 17 had other bacterial disease (pneumonia, acute otitis media, pyelonephritis, bacteraemia, shigella or salmonella gastroenteritis). All the latter had, upon admission, symptoms, signs, laboratory tests or imaging studies suggesting a bacterial aetiology.

CONCLUSIONS

In this large cohort, all infants who appeared well on admission and had normal clinical, laboratory and imaging studies had benign (non-bacterial) disease. In an infant who appears well and has no evidence of bacterial disease, it is reasonable to observe the infant and withhold lumbar puncture. Prospective studies should be carried out to confirm this approach.

Endotoxin-induced myeloid-derived suppressor cells inhibit alloimmune responses via heme oxygenase-1

Inflammation and cancer are associated with impairment of T-cell responses by a heterogeneous population of myeloid-derived suppressor cells (MDSCs) coexpressing CD11b and GR-1 antigens. MDSCs have been recently implicated in costimulation blockade-induced transplantation tolerance in rats, which was under the control of inducible NO synthase (iNOS). Herein, we describe CD11b+GR-1+MDSC-compatible cells appearing after repetitive injections of lipopolysaccharide (LPS) using a unique mechanism of suppression. These cells suppressed T-cell proliferation and Th1 and Th2 cytokine production in both mixed lymphocyte reaction and polyclonal stimulation assays. Transfer of CD11b+ cells from LPS-treated mice in untreated recipients significantly prolonged skin allograft survival. They produced large amounts of IL-10 and expressed heme oxygenase-1 (HO-1), a stress-responsive enzyme endowed with immunoregulatory and cytoprotective properties not previously associated with MDSC activity. HO-1 inhibition by the specific inhibitor, SnPP, completely abolished T-cell suppression and IL-10 production. In contrast, neither iNOS nor arginase 1 inhibition did affect suppression. Importantly, HO-1 inhibition before CD11b+ cell transfer prevented the delay of allograft rejection revealing a new MDSC-associated suppressor mechanism relevant for transplantation.

Induction of tolerance in solid organ transplantation: the rationale to develop clinical protocols in liver transplantation

Minimization or withdrawal of immunosuppressive treatments after organ transplantation represents a major objective for improving quality of life and long-term survival of grafted patients. Such a goal may be reached under some clinical conditions, particularly in liver transplantation, making these patients good candidates for tolerance trials. In this context in liver transplantation, the central questions are (1) how to promote the natural propensity of the liver graft to be accepted, (2) which type of immunosuppressive drug should be used for induction and maintenance, and (3) which biomarkers could be used to discriminate tolerant patients from those requiring long-term immunosuppression. Induction therapies using aggressive T-cell-depleting agents may favor graft acceptance. However, persistent and/or rapidly reemerging cell lines, such as memory-type cells or CD8(+) T cells, could represent a significant barrier for induction of tolerance. The type of maintenance drugs also remains questionable. Calcineurin inhibitors may be eventually deleterious in the context of tolerance protocols, through inhibitory effects on regulatory T cells, that are not observed with rapamycin. In conclusion, significant efforts must be made to achieve reliable strategies for immunosuppression minimization or withdrawal after organ transplantation into the clinics.