Nanoarchitectures for efficient IgE cross-linking on effector cells to study amoxicillin allergy

Background

Amoxicillin (AX) is nowadays the β-lactam that more frequently induces immediate allergic reactions. Nevertheless, diagnosis of AX allergy is occasionally challenging due to risky in vivo tests and non-optimal sensitivity of in vitro tests. AX requires protein haptenation to form multivalent conjugates with increased size to be immunogenic. Knowing adduct structural features for promoting effector cell activation would help to improve in vitro tests. We aimed to identify the optimal structural requirement in specific cellular degranulation to AX using well-precised nanoarchitectures of different lengths.

Method

We constructed eight Bidendron Antigens (BiAns) based on polyethylene glycol (PEG) linkers of different lengths (600–12,000 Da), end-coupled with polyamidoamine dendrons that were terminally multi-functionalized with amoxicilloyl (AXO). In vitro IgE recognition was studied by competitive radioallergosorbent test (RAST) and antibody–nanoarchitecture complexes by transmission electron microscopy (TEM). Their allergenic activity was evaluated using bone marrow-derived mast cells (MCs) passively sensitized with mouse monoclonal IgE against AX and humanized RBL-2H3 cells sensitized with polyclonal antibodies from sera of AX-allergic patients.

Results

All BiAns were recognized by AX-sIgE. Dose-dependent activation responses were observed in both cellular assays, only with longer structures, containing spacers in the range of PEG 6000–12,000 Da. Consistently, greater proportion of immunocomplexes and number of antibodies per complex for longer BiAns were visualized by TEM.

Conclusions

BiAns are valuable platforms to study the mechanism of effector cell activation. These nanomolecular tools have demonstrated the importance of the adduct size to promote effector cell activation in AX allergy, which will impact for improving in vitro diagnostics.

     

In vitro and in vivo characterization of a Bordetella bronchiseptica mutant strain with a deep rough lipopolysaccharide structure

Bordetella bronchiseptica is closely related to Bordetella pertussis, which produces respiratory disease primarily in mammals other than humans. However, its importance as a human pathogen is being increasingly recognized. Although a large amount of research on Bordetella has been generated regarding protein virulence factors, the participation of the surface lipopolysaccharide (LPS) during B. bronchiseptica infection is less understood. To get a better insight into this matter, we constructed and characterized the behavior of an LPS mutant with the deepest possible rough phenotype. We generated the defective mutant B. bronchiseptica LP39 on the waaC gene, which codes for a heptosyl transferase involved in the biosynthesis of the core region of the LPS molecule. Although in B. bronchiseptica LP39 the production of the principal virulence determinants adenylate cyclase-hemolysin, filamentous hemagglutinin, and pertactin persisted, the quantity of the two latter factors was diminished, with the levels of pertactin being the most greatly affected. Furthermore, the LPS of B. bronchiseptica LP39 did not react with sera obtained from mice that had been infected with the parental strain, indicating that this defective LPS is immunologically different from the wild-type LPS. In vivo experiments demonstrated that the ability to colonize the respiratory tract is reduced in the mutant, being effectively cleared from lungs within 5 days, whereas the parental strain survived at least for 30 days. In vitro experiments have demonstrated that, although B. bronchiseptica LP39 was impaired for adhesion to human epithelial cells, it is still able to survive within the host cells as efficiently as the parental strain. These results seem to indicate that the deep rough form of B. bronchiseptica LPS cannot represent a dominant phenotype at the first stage of colonization. Since isolates with deep rough LPS phenotype have already been obtained from human B. bronchiseptica chronic infections, the possibility that this phenotype arises as a consequence of selection pressure within the host at a late stage of the infection process is discussed.     

Interaction between α- and β-adrenoceptors in rat pineal adenosine cyclic 3′,5′-monophosphate phosphodiesterase activation

Summary The adrenergic regulation of the low-Km pineal cAMP phosphodiesterase (PDE) activity was studied in adult female rats. PDE activity showed a transient enhancement (up to 42%) during the process of degeneration of pineal sympathetic nerve terminals that followed superior cervical ganglionectomy (SCGx), thus confirming the neural modulation of the enzyme. Treatment with isoproterenol (0.3–5.0 mg/Kg) increased significantly PDE activity within 2 hours. Phenylephrine induced a significant increase of pineal PDE only at a 10 mg/Kg dose, while at a lower dose (1 mg/Kg) it potenciated the stimulatory effect of isoproterenol. Treatment of pineal organ cultures with 100 M propranolol inhibited norepinephrine (NE)-induced PDE activity while 100 M phentolamine had no significant effect. Propranolol at doses unable to alter thein vitro NE-induced stimulation of pineal PDE activity (1 M), antagonized such NE effect when used in combination with 1 uM phentolamine. At equimolecular concentrations (1 M) the mixed --adrenergic agonist NE was more effective than the -adrenergic agonist isoproterenol to increase pineal PDEin vitro. These resultsSupported by grant no. 6638, Consejo Nacional de Investigaciones Cientificas y Técnicas de la RepÚblica Argentina (CONICET), Argentina.Established Investigator, CONICET.     

Immediate repair of urethroperineal fistulas after abdominoperineal amputation by means of a cutaneo-muscular flap of the gluteus maximus. Apropos of 2 successfully treated cases

Although a rare complication, the development of a urethro-perineal urinary fistula immediately after abdomino-perineal amputation is a difficult problem to solve. The fragility of the membranous urethra immediately in contact with the exenterated pelvic cavity which takes several weeks to fill in makes any attempt at isolated direct suture very hazardous. Secondary repair is also frequently difficult and the "functional prognosis is far from being always favourable". The major handicap resulting from the perpetuation of this type of fistula has led us to propose an attempt at immediate repair as soon as it is diagnosed with filling of the pelvi-perineal cavity by a cutaneo-muscular flap taken from gluteus maximus. In the two cases in which this treatment was performed, the fistula was cured and a good quality functional result was obtained.     

Predictors of health-related quality of life in Parkinson’s disease: the impact of overlap between health-related quality of life and clinical measures

Quality of Life Research - This study aimed to determine predictors of health-related quality of life (HRQoL) in Parkinson's disease (PD) and to explore their predictive value before and after...     

Association Between Maternal Work and Exclusive Breastfeeding in Countries of Latin America and Caribbean

Maternal and Child Health Journal - The aim of this study was to estimate the association between individual and contextual characteristics related to maternal work and exclusive breastfeeding...     

Disrespect and Abuse in Obstetric Care in Mexico: An Observational Study of Deliveries in Four Hospitals

Maternal and Child Health Journal - To identify and describe the frequency and characteristics of disrespect and abuse practices towards women during facility-based delivery in four hospitals in...     

Impacto del nivel socioeconómico sobre el perfil del paciente amputado de miembro inferior por causa no traumática

IntroductionTo analyse the influence of socioeconomic status on the clinical profile of patients undergoing non-traumatic lower-limb amputation.MethodsRetrospective study of 697 lower-limb amputee patients in an Angiology and Vascular Surgery Department during a 5-year period. Patients were classified according to their socioeconomic status (low, medium and high). We analysed demographic (age and gender) and clinical variables (cause of amputation, comorbidity, cardiovascular risk factors and amputation level).ResultsMean age was 70.5 ± 11.9 years, and the median was 72 years. The low socioeconomic status group presented a higher frequency of amputations in men. Cardiovascular risks factors were more frequent in this socioeconomic group, and the difference was statistically significant for diabetes (85.8% low, 69.3% medium, 65% high; P<.01) and obesity (31.4% low, 22.6% medium, 12.5% high, P<.01). Diabetic retinopathy was the only comorbidity with a significant association with low socioeconomic status (21.1% low, 15.3% medium, 12.5% high, P<.03). Regarding the cause for amputation, there was no difference in terms of socioeconomic status. The low socioeconomic level showed a higher frequency of major amputation, which was a significant difference (63.6% low, 41.2% medium, 55% high, P<.04) and a higher predisposition for this amputation level.ConclusionsThe low socioeconomic status has been shown to determine an unfavourable vascular risk profile in lower-limb non-traumatic amputees and a higher predisposition of a major amputation. This socioeconomic level demonstrates a negative influence on these patients’ diabetes, obesity and diabetic retinopathy.