EEG rhythmic and arrhythmic spectral components and functional connectivity at resting state may predict the development of synucleinopathies in idiopathic REM sleep behavior disorder

STUDY OBJECTIVES

Idiopathic/isolated REM-sleep behavior disorder (iRBD) often precedes the onset of synucleinopathies. Here, we investigated whether baseline resting-state EEG advanced spectral power and functional connectivity differ between iRBD patients who converted towards a synucleinopathy at follow-up and those who did not.

METHODS

Eighty-one participants with iRBD (66.89±6.91 years) underwent a baseline resting-state EEG recording, a neuropsychological assessment and a neurological examination. We estimated EEG power spectral density using standard analyses and derived spectral estimates of rhythmic and arrhythmic components. Global and pairwise EEG functional connectivity analyses were computed using the weighted phase-lag index (wPLI). Pixel-based permutation tests were used to compare groups.

RESULTS

After a mean follow-up of 5.01±2.76 years, 34 patients were diagnosed with a synucleinopathy (67.81±7.34 years) and 47 remained disease-free (65.53±7.09 years). Among patients who converted, 22 were diagnosed with Parkinson's disease and 12 with dementia with Lewy bodies. As compared to patients who did not convert, patients who converted exhibited at baseline higher relative theta standard power, steeper slopes of the arrhythmic component and higher theta rhythmic power mostly in occipital regions. Furthermore, patients who converted showed higher beta global wPLI but lower alpha wPLI between left temporal and occipital regions.

CONCLUSION

Analyses of resting-state EEG rhythmic and arrhythmic components and functional connectivity suggest an imbalanced excitatory-to-inhibitory activity within large-scale networks, which is associated with later development of a synucleinopathy in iRBD patients.

Managing the unknown or the art of preventing SARS-CoV-2 infection in workplaces in a context of evolving science, precarious employment, and communication barriers. A qualitative situational analysis in Quebec and Ontario

Introduction

The issue of communications in the public space, and in particular, in the workplace, became critical in the early stages of the SARS-CoV-2 pandemic and was exacerbated by the stress of the drastic transformation of the organization of work, the speed with which new information was being made available, and the constant fear of being infected or developing a more severe or even fatal form of the disease. Although effective communication is the key to fighting a pandemic, some business sectors were more vulnerable and affected than others, and the individuals in particular socio-demographic and economic categories were proportionately more affected by the number of infections and hospitalizations, and by the number of deaths. Therefore, the aim of this article is to present data related to issues faced by essential workers interacting with the public and their employers to mitigate the contagion of SARS-CoV-2 (COVID-19) at work.

Methods

Following the constructivist paradigm, an interpretative qualitative design was used to conduct one-on-one interviews with precarious/low-wage, public-contact workers (N = 40), managers (N = 16), and key informants (N = 16) on topics related to their work environments in the context of COVID-19 prevention.

Results

This article has highlighted some aspects of communication in the workplace essential to preventing COVID-19 outbreaks (e.g., access to information in a context of fast-changing instructions, language proficiency, transparency and confidentiality in the workplace, access to clear guidelines). The impact of poor pre-pandemic working relations on crisis management in the workplace also emerged.

Discussion

This study reminds us of the need to develop targeted, tailored messages that, while not providing all the answers, maintain dialog and transparency in workplaces.

A rapid scoping review of COVID-19 and vulnerable workers: Intersecting occupational and public health issues

BACKGROUND

This article reports the results of a rapid scoping review of the literature on COVID-19 transmission risk to workers in essential sectors such as retail, health care, manufacturing, and agriculture, and more particularly the experiences of workers in precarious employment and social situations.

METHODS

Following scoping review methods, we included 30 studies that varied in terms of methodology and theoretical approaches. The search included peer-reviewed articles and grey literature published between March and September 2020.

RESULTS

Based on the studies reviewed, we found that COVID-19 infection and death rates increased not only with age and comorbidities, but also with discrimination and structural inequities based on racism and sexism. Racial and ethnic minority workers, including migrant workers, are concentrated in high-risk occupations and this concentration is correlated to lower socioeconomic conditions. The COVID-19 pandemic appears in the occupational health and safety spotlight as an exacerbator of already existing socioeconomic inequalities and social inequalities in health, especially in light of the intersection of issues related to racism, ethnic minority status, and sexism.

CONCLUSIONS

This review provides early evidence about the limitations of institutions' responses to the pandemic, and their capacity to provide a safe and decent working environment for all workers, regardless of their employment status or the social protections they may enjoy under normal circumstances. It is also important to think about these issues in the postpandemic context, when conditions of precariousness and vulnerability persist and possibly worsen.

Role and Responsibilities of Supervisors in the Sustainable Return to Work of Workers Following a Work-Related Musculoskeletal Disorder

Purpose Supervisors play an important role during the return to work (RTW) of injured workers. Yet little research has been done on the actions associated with this role or the contexts in which they are taken. The purpose of this study was to develop courses of action to promote supervisors' involvement in the process aimed at achieving sustainable RTW for workers following a work-related musculoskeletal disorder (MSD), and to verify their pertinence, feasibility, and applicability in practice. Methods A two-phase qualitative method was used. (1) Secondary content analysis of 46 interviews of 14 workers post-MSD and 32 other actors in the RTW process, conducted during a prior case study, yielded proposals for courses of action composed of specific actions for supervisors. (2) The pertinence, feasibility, and applicability of these courses of action and specific actions were explored, first, through a self-administered questionnaire to initiate individual reflection, and later in greater depth through focus groups to identify the different contexts in which they might be applicable. Thematic analysis was performed for each phase. Results Eight proposed courses of action, including specific concrete actions and conditions influencing supervisors' involvement, were developed by the researchers and generally perceived as pertinent and feasible by the participants. Several aspects of the organizational context appeared to influence implementation of these courses of action within the organizations. Conclusion Organizational context appears to influence the application of these courses of action, as do the conditions under which they are implemented.

Cumulative stigma among injured immigrant workers: a qualitative exploratory study in Montreal (Quebec, Canada)

Purpose: This paper presents the phenomenon of stigmatisation among injured immigrant and ethnocultural minority workers experiencing a long-standing disability. Stigmatisation was one of the main findings of our study, the aim of which was to gain insight into the work rehabilitation process in the context of intercultural relations in Quebec. Various categories of stakeholders took part in the study, which sought to describe their experiences and perspectives and to identify the constraints, barriers, facilitators, and specific needs they encounter in terms of intercultural competencies.Methods: A purposive sample of 40 individuals was selected and divided into four groups: workers (N = 9), clinicians (N = 15), workers' compensation board rehabilitation experts (N = 14), and workplace representatives (N = 2). Semi-structured interviews were conducted using the critical incident technique, combined with an "explicitation" interviewing technique. Data collection and analysis procedures were based on grounded theory.Results: This study shows that immigrant and ethnocultural minority workers may experience stigmatisation as a cumulative process involving different concomitant parts of their "identity": age, gender, social class, ethnicity, mental health, and occupational injuries. Cumulative stigma may aggravate personal distress and feelings of shame, rejection, and disqualification from full social acceptance. Negative anticipatory judgements made by practitioners may undermine the therapeutic relationship and breach mutual trust and confidence.Conclusions: The phenomenon of stigmatisation is well documented in the sociological and health literature, but studies tend to focus on only one type of stigma at a time. Future research should focus on the cumulative process of stigmatisation specifically affecting immigrant and ethnocultural minority workers and its potentially damaging impact on self-concept, healthcare delivery, rehabilitation interventions, and the return to work.Implications for rehabilitationThe repetition of certain clinical situations with people from certain groups should not lead practitioners to undue generalizations, even if they may sometimes be accurate; these generalizations must always be verified on a case by case basis.Ethnicity and culture, along with other social attributions, should serve as working hypotheses or support tools in health communication, not as hindrances to clinical reasoning.Practitioners should deepen their understanding of the patient's treatment expectations and the support available for rehabilitation in his family and community.Stigma in the context of care is linked to the idea of conforming to the proposed institutional models of care (including expected beliefs, attitudes, and behaviours). Therefore, practitioners should be aware that alleged differences, misunderstanding or disagreements can highlight an asymmetry in practitioner-patient power relationships.Organisations should also promote exchange and reflection on how to adapt their institutional models to avoid asymmetrical power relations.Intercultural training should be promoted at the various organisational levels so that managers, decision-makers, and practitioners share a common knowledge of the challenges of intervention in multi-ethnic settings.

Le retour au travail d’immigrants ayant subi une lésion professionnelle : les embûches de la rencontre interculturelle et la précarité du lien d’emploi

Cet article rapporte une partie des résultats d'une étude exploratoire sur le processus de réadaptation et de retour au travail en contexte de relations interculturelles. Cette étude avait deux objectifs : identifier les stratégies mises de l'avant par les différents acteurs pour faciliter le processus de réadaptation et de retour au travail des travailleurs immigrants et décrire les contraintes, les obstacles et les aides au processus selon la perspective des différents acteurs. Des entrevues semi-dirigées ont ainsi été menées auprès de 47 répondants : cliniciens, agents d'indemnisation et conseillers en réadaptation de la CNESST, employeurs et travailleurs immigrants victimes d'une lésion reconnue et indemnisée. Au-delà des barrières linguistiques et culturelles, deux facteurs nuisent au retour en emploi des travailleurs immigrants : d'une part, la précarité du lien d'emploi freine leurs efforts et mine leur volonté de consolider leur état de santé et, d'autre part, la menace ou la perte réelle du lien d'emploi amène une rupture symbolique dans leur processus d'intégration. Cette rupture est importante pour ceux qui sont surqualifiés pour leur poste, surtout si leur emploi est un passage obligé pour acquérir une expérience de travail au Canada et viser ensuite un emploi à la hauteur de leurs compétences. Le processus de réadaptation peut soit se transformer en un « parcours déshonorant », soit fournir une occasion d'améliorer sa situation sur un marché du travail discriminant. Adapter les programmes à la réalité de ces travailleurs immigrants est possible, mais pose un dilemme moral et éthique : comment motiver les travailleurs à se rétablir tout en explorant un autre créneau d'emploi si leur lien d'emploi risque d'être rompu, alors que les règles relatives au droit de retour au travail prévoient la réintégration de l'emploi prélésionnel ou tout autre poste jugé équivalent?

Age-related changes in sleep spindles characteristics during daytime recovery following a 25-hour sleep deprivation

OBJECTIVES

The mechanisms underlying sleep spindles (~11-15 Hz; >0.5 s) help to protect sleep. With age, it becomes increasingly difficult to maintain sleep at a challenging time (e.g., daytime), even after sleep loss. This study compared spindle characteristics during daytime recovery and nocturnal sleep in young and middle-aged adults. In addition, we explored whether spindles characteristics in baseline nocturnal sleep were associated with the ability to maintain sleep during daytime recovery periods in both age groups.

METHODS

Twenty-nine young (15 women and 14 men; 27.3 y ± 5.0) and 31 middle-aged (19 women and 13 men; 51.6 y ± 5.1) healthy subjects participated in a baseline nocturnal sleep and a daytime recovery sleep after 25 hours of sleep deprivation. Spindles were detected on artifact-free Non-rapid eye movement (NREM) sleep epochs. Spindle density (nb/min), amplitude (μV), frequency (Hz), and duration (s) were analyzed on parasagittal (linked-ears) derivations.

RESULTS

In young subjects, spindle frequency increased during daytime recovery sleep as compared to baseline nocturnal sleep in all derivations, whereas middle-aged subjects showed spindle frequency enhancement only in the prefrontal derivation. No other significant interaction between age group and sleep condition was observed. Spindle density for all derivations and centro-occipital spindle amplitude decreased whereas prefrontal spindle amplitude increased from baseline to daytime recovery sleep in both age groups. Finally, no significant correlation was found between spindle characteristics during baseline nocturnal sleep and the marked reduction in sleep efficiency during daytime recovery sleep in both young and middle-aged subjects.

CONCLUSION

These results suggest that the interaction between homeostatic and circadian pressure modulates spindle frequency differently in aging. Spindle characteristics do not seem to be linked with the ability to maintain daytime recovery sleep.

Isolation and characterization of human airway fibroblasts in culture

Asthma is considered an airway inflammatory disorder characterized by variable airflow obstruction and airway hyperresponsiveness (1). The inflammatory component of asthma has been studied extensively over the past few years, but, more recently, the potential contribution of airway wall remodeling to functional and clinical changes has been emphasized (2,3). Although the methods of sampling of bronchial tissue were previously limited, being obtained mostly from autopsic or surgical specimens, they have improved recently.

Synergistic action of endothelin (ET)-1 on the activation of bronchial fibroblast isolated from normal and asthmatic subjects

Bronchial subepithelial fibrosis is an histological characteristic of asthma. Cytokines and other mediators, such as PDGF-BB, TGF-beta1 and ET-1 found in the asthmatic submucosa can potentially activate a repair process that leads to fibroblast proliferation and collagen synthesis. The mechanisms of modulation of the repair process leading to extracellular matrix deposition are still to be documented. In this study, we assessed the in vitro proliferation and collagen synthesis of bronchial fibroblasts isolated from normal and asthmatic subjects in response to ET-1, platelet-derived growth factor (PDGF)-BB and transforming growth factor (TGF)-beta1 alone or in combination, in the presence or absence of dexamethasone. The combination of ET-1 with one of the other two growth factors, or the triple combination, significantly increased DNA synthesis and collagen production of bronchial fibroblasts isolated from both normal and asthmatic subjects, but the same growth factors used separately had no significant effect on the same parameters. These results suggest that the simultaneous presence of ET-1, PDGF-BB and TGF-beta1 in both normal and asthmatic subjects is necessary to activate bronchial fibroblast proliferation and collagen synthesis. As these mediators are present in the submucosa of the asthmatic bronchi, they could be responsible, at least in part, for the accumulation of collagen in the mucosa.

Adenosine induces cyclic-AMP formation and inhibits endothelin-1 production/secretion in guinea-pig tracheal epithelial cells through A(2B) adenosine receptors

1. The adenosine receptor subtype mediating adenosine 3' : 5'-cyclic monophosphate (cyclic AMP) formation and the effect of its activation on endothelin-1 (ET-1) secretion were studied in primary cultures of tracheal epithelial cells. 2. Adenosine analogues showed the following rank order of potency (pD(2) value) and intrinsic activity on the generation of cyclic AMP by tracheal epithelial cells: 5'-N-ethylcarboxyamidoadenosine (NECA, A(1)/A(2A)/A(2B), pD(2): 5.44+/-0.16)>adenosine (ADO, non selective, pD(2): 4.99+/-0. 09; 71+/-9% of NECA response) >/=2-Cl-adenosine (2CADO, non selective, pD(2): 4.72+/-0.14; 65+/-9% of NECA response)>>>CGS21680 (A(2A); inactive at up to 100 microM). 3. Cyclic AMP formation stimulated by NECA in guinea-pig tracheal epithelial cells was inhibited by adenosine receptor antagonist with the following order of apparent affinity (pA(2) value): Xanthine amine congeners (XAC, A(2A)/A(2B), 7.89+/-0.22)>CGS15943 (A(2A)/A(2B), 7.24+/-0. 26)>ZM241385 (A(2A), 6.69+/-0.14)>DPCPX (A(1), 6.51+/-0. 14)>3n-propylxanthine (weak A(2B), 4.30+/-0.10). This rank order of potency is typical for A(2B)-adenosine receptor. 4. Adenosine decreased basal and LPS-stimulated irET production in a concentration-dependent manner. Moreover, NECA but not CGS21680 inhibited LPS-induced irET production. 5. The inhibitory effect of NECA on LPS-induced irET production was reversed by XAC (pA(2)=8.84+/-0. 12) and DPCPX (pA(2)=8.10+/-0.22). 6. These results suggested that adenosine increased cyclic AMP formation and inhibited irET production/secretion by guinea-pig tracheal epithelial cells through the activation of a functional adenosine receptor that is most likely the A(2B) subtype. This adenosine receptor may be involved in the regulation of the level of ET-1 production/secretion by guinea-pig tracheal epithelial cells in physiological as well as in pathophysiological conditions.

Stroke-like episodes in autosomal recessive cytochrome oxidase deficiency

Stroke-like episodes, defined as periods of acute localized neurological dysfunction during which brain imagery suggests cerebral ischemia but vascular anatomy is normal, occurred in 3 patients with autosomal recessive Saguenay-Lac St-Jean (SLSJ) cytochrome oxidase (COX) deficiency. The patients developed focal neurological deterioration and frontal hypodensities on cerebral computerized tomography (CT). Arteriography, performed in 1 patient during an acute episode, showed normal vascular anatomy. Nevertheless, capillary shunting was evident both in regions that appeared abnormal on the initial cerebral CT study and in regions that appeared normal but subsequently developed Leigh disease. Stroke-like episodes did not exacerbate systemic acidosis, and acidotic decompensations occurred independently of stroke-like episodes. In conclusion, stroke-like episodes occur in autosomal recessively inherited congenital lactic acidoses as well as in those caused by mitochondrial DNA mutations. In some cases, acute localized neurovascular changes occur in regions that subsequently develop Leigh disease.

In vitro procollagen synthesis and proliferative phenotype of bronchial fibroblasts from normal and asthmatic subjects

Asthma is characterized histologically by a bronchial subepithelial fibrosis. Cytokines and other mediators released in the asthmatic chronic inflammatory microenvironment can activate the repair process that leads to fibroblast proliferation and collagen synthesis. To our knowledge, there are no data regarding the effect of a chronic inflammatory microenvironment on the phenotype of human bronchial fibroblasts. In the present study, we address this issue by comparing bronchial fibroblasts isolated from normal and asthmatic subjects in terms of: (a) proliferation over cell passage; (b) in vitro lifespan; (c) proliferative response to transforming growth factor-beta 1, platelet-derived growth factor-BB, dexamethasone, and retinoic acid; and (d) base-line synthesis of procollagens I and III. Bronchial fibroblasts from asthmatic subjects demonstrated lower DNA synthesis with cell passage than bronchial fibroblasts from normals. The in vitro lifespan of asthmatic bronchial fibroblasts was lower than in those from normal subjects and was significantly correlated with airway responsiveness. Platelet-derived growth factor-BB and dexamethasone increased 3H-thymidine incorporation in asthmatic bronchial fibroblasts without having any significant effect on normal fibroblast proliferation. Transforming growth factor-beta 1 and retinoic acid had no significant effect on bronchial fibroblast proliferation. Base-line procollagens I and III synthesis measurements showed no differences between normal and asthmatic fibroblasts. Taken together, these results indicate that the chronic inflammatory microenvironment found in asthma can modulate some aspects of bronchial fibroblast phenotype.

Airway inflammation and structural changes in airway hyper-responsiveness and asthma: an overview

Asthma treatment has moved from bronchodilator therapy to an emphasis on anti-inflammatory therapy. Airway inflammation is believed to induce airway hyper-responsiveness (AHR) through the release of mediators that increase the airway response to agonists. However, the exact contribution of airway inflammation in the physiology of airway hyper-responsiveness remains undefined. Structural modifications in airways resulting from inflammation may contribute to the development and persistence of AHR and the development of asthma. This paper reviews some of the main components of airway inflammation and structural changes in asthma, and discusses how these processes may interact to modify airway function and induce respiratory symptoms.

Peripherally inserted central catheters in infants and children

PURPOSE

To determine prospectively the feasibility, complications, and mid- and long-term advantages of peripheral insertion of central catheters in infants and children.

MATERIALS AND METHODS

During a 15-month period between March 1995 and June 1996, a total of 285 catheter placement attempts were made to peripherally insert central catheters in 183 pediatric patients (89 boys, 94 girls). Phlebographic guidance was used, and the catheters were inserted below the elbow in 99% of cases. Catheter insertion was indicated for prolonged antibiotic therapy in 108 patients (158 catheter placement attempts), hematologic or oncologic care in 24 patients (40 attempts), total parenteral nutrition in 16 patients (46 attempts), and venous access for fluid or blood in 35 patients (41 attempts). The success rate and complications were recorded along with the indication, patient age, and duration of catheter placement.

RESULTS

One hundred fifty-two of 158 (96%) catheter placement attempts were successful in outpatients (n = 108), 124 of 127 (98%) in hospitalized patients (n = 75), and 70 of 73 (96%) in patients aged less than 1 year. Infection and pericatheter venous thrombosis were the main complications and were seen in 17 of 276 (6%) and one of 276 (0.3%) catheter placement attempts, respectively. Catheter occlusion occurred in 23 of 276 (8%) catheter placement attempts.

CONCLUSION

Peripheral insertion of central catheters was highly feasible in infants and children with this protocol. Such catheters were well tolerated in the pediatric population with a low frequency of complications.

Lower airways remodeling in nonasthmatic subjects with allergic rhinitis

We analyzed by immunohistochemistry the distribution of types I, II, III, IV, V, and VII collagens, laminin, and fibronectin in the bronchial biopsy specimens of nonasthmatic subjects with seasonal allergic rhinitis (n = 8) and compared these results with those found in mild stable allergic asthmatics (n = 6) and normal controls (n = 5). The content of type I and III collagens was increased in rhinitic subjects compared with controls. These collagens were focally deposited in the reticular basement membrane area. Three subjects with allergic rhinitis had no fibronectin deposition in their basement membrane, as in controls, whereas the other five had a focal fibronectin deposition. In asthmatic patients, type I and III collagens and fibronectin were more abundant and more uniformly distributed underneath the basement membrane than they were in rhinitic subjects. Expression of type II, IV, V, and VII collagens and laminin were similar in the three groups. Electron microscopic and immunohistochemical analyses of bronchial mucosa showed a network of myofibroblasts beneath the epithelium in rhinitis as in asthma subjects. These data show that the irregularly distributed subepithelial fibrosis observed in subjects with allergic rhinitis results from the deposition of type I and III collagens and fibronectin, probably produced by bronchial myofibroblasts. These results suggest the presence of an active structural remodeling in the lower airways of allergic rhinitic subjects that is similar in nature to that seen in asthma, although less marked.

Morphologic and functional properties of bronchial cells isolated from normal and asthmatic subjects

Recent advances in biomedical sciences have led to the development of various methods for the evaluation of the physiopathology of respiratory diseases. This study reports morphologic and functional features of cells isolated by a new method from bronchial biopsies of normal and asthmatic subjects. Both epithelial and fibroblastic cells were isolated from the same biopsies using collagenase. The cells were cultured for several passages and stored frozen. Two selective culture media were used in order to obtain pure epithelial and fibroblastic cell populations. Immunofluorescence analysis of intermediate filaments, keratins, and vimentin confirmed the type of the isolated cells. The proportions of alpha-actin-expressing cells varied among the fibroblastic cell populations isolated from normal and asthmatic subjects. Interestingly, the population containing high numbers of alpha-actin-expressing cells and presenting the fastest collagen contraction kinetic was isolated from bronchial biopsies of an asthmatic subject. Moreover, the fibroblastic cells that showed the best contractile properties 24 h after their seeding in floating collagen gels were isolated from bronchial biopsies of asthmatic patients having PC20 values below 1 mg/ml. On the basis of these data, we propose a new approach to isolate, culture and characterize human bronchial cells in vitro.

Renovascular hypertension in children: curability predicted with negative intrarenal Doppler US results

PURPOSE

To assess whether intrarenal Doppler ultrasound (US) enables prediction of the outcome of renovascular hypertension in a pediatric population.

MATERIALS AND METHODS

A prospective study of 29 children with renin-mediated hypertension was performed. In these patients, intrarenal Doppler US was performed before angiography. Doppler US and angiographic findings were compared with patient outcome with respect to treatment required and blood pressure (BP) status after therapy. Cure was defined as a normal BP without medication.

RESULTS

Intrarenal Doppler US was positive in 15 patients (52%), group 1, and negative in 14 patients (48%), group 2. In 10 patients (67%) in group 1, the severity of the vascular lesion precluded permanent cure. Cure was achieved in all patients in group 2, except for patients with neurofibromatosis. Thus, there was a statistically significant association (P < .05) between cure and a negative Doppler US result.

CONCLUSION

In children with renovascular hypertension, a negative Doppler US result enables the prediction that a cure is more likely to be achieved with endovascular therapy or surgery.

Hyperammonemia-hyperornithinemia-homocitrullinuria syndrome: neurologic, ophthalmologic, and neuropsychologic examination of six patients

We report the clinical, electrophysiologic, ophthalmologic, and neuropsychologic features of six patients with hyperammonemia-hyperornithinemia-homocitrullinuria syndrome, an inborn error of ornithine metabolism. Pyramidal signs, decreased vibration sense, bucco-facio-lingual dyspraxia, and learning difficulties or subnormal intelligence were found in the majority. Anomalies of peripheral nerve conduction velocity and of evoked potentials were common, and one patient had markedly abnormal white matter images on cranial magnetic resonance imaging. One patient had retinal depigmentation and chorioretinal thinning. The clinical severity varied greatly among patients; in general, the three younger patients had less neurologic and intellectual impairment than did the three older patients. Only two of our patients have had episodes of symptomatic hyperammonemia. We conclude that hyperammonemia-hyperornithinemia-homocitrullinuria syndrome can be associated with widespread manifestations in the central and peripheral nervous systems. Although the control of hyperammonemia is an essential element in the treatment of these patients, the relationship of hyperammonemia to the chronic neuropsychologic problems of these patients is unclear.

Modification of RBC properties by an autoantibody. Binding to RBC senescent antigen

It has been reported that natural antibodies alter aging RBCs, so increasing their vulnerability for removal from the blood stream. Results presented indicate that binding of anti-Gal, a natural antibody, to erythrocytes increases RBC rigidity in terms of microviscosity and deformability. Removal of RBCs from circulation could, at least in part, depend on these alterations.

Blood banking-induced senescent modifications on red blood cells

In the past few years significant progress has been made in the extension of storage time for red blood cells (RBCs). Albeit this, membrane still undergoes damage during conservation under blood bank conditions, reducing red cell viability following transfusion. Consequently in this study, we evaluated the presence of senescence indices (appearing on RBCs during in vivo aging) on blood bank stored RBCs, more precisely the 4.1a/4.1b ratio and the binding of autologous immunoglobulins. Although not significant, a slight increase (0.995 +/- 0.070 to 1.008 +/- 0.058) was observed in the 4.1a/4.1b ratio during the first three weeks of storage. A rapid and significant (p less than 0.001) increase in the number of cell-bound IgGs (91 +/- 22 to 913 +/- 92), following incubation with purified autologous IgGs, was observed in the first days of storage. Thus, following transfusion, binding of autologous IgGs to stored RBCs could influence post-transfusion viability.

Sodium-phosphate cotransport and vascular reactivity

Inorganic phosphate (PO4) alters vascular reactivity in vivo as well as in vitro. In the latter condition, low PO4 reduces, while high PO4 augments reactivity. We used phosphonoformate (PFA), a phosphaturic compound, binding the renal Na-PO4 co-transporter, to examine the existence of such a transport mechanism in selected vascular smooth muscles (VSM). Strips of aorta (A), mesenteric artery (MA), and vein (MV) were obtained from normal rabbits. All tissues were either superfused in normal PO4 (Group 1: 3 mg/dL), then in modified low PO4 (Group 2: 0 mg/dL) or high PO4 (Group 3: 9 mg/dL) Ringer's solutions. The effect of angiotensin II (AII: 10-11 to 10-8M) was tested on each tissue preparation, and contraction values obtained in the presence of PFA (18.5 micrograms/ml:0.018 ml/min) were compared to control responses in the absence of the drug. In Group 1, the contractions of A were reduced by 23% during PFA, for higher doses of AII only, compared to controls (p less than 0.01). Similarly, the contractions of MA in the presence of PFA were reduced at higher doses of AII, by 22% (p less than 0.01). Finally, the contractions of MV were reduced by 75% (p less than 0.01) for all doses of AII. In Group 2, there was no difference in vascular tissue contraction between controls and PFA, whereas in Group 3, the reduction in A, MA, and MV contractions in PFA-treated tissues were approximately twice as extensive as in Group 1 (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

The large vestibular aqueduct syndrome and sensorineural hearing loss in the pediatric population

Sensorineural hearing loss, associated with a dilated vestibular aqueduct, is often described as progressive. Since 1982, computed tomography of the mastoids has become part of the routine investigation of deaf children at Sainte-Justine Hospital. Using clinical, audiometric and radiological material from 130 patients with sensorineural hearing loss, we identified 18 patients with enlarged vestibular aqueducts. The large vestibular aqueduct population was then compared to the normal vestibular aqueduct patients in regard to the degree and evolution of the sensorineural hearing loss. Progression of hearing loss was noted in 46% of patients in the presence of large vestibular aqueducts as compared to 35% in the absence of this anomaly. Normal radiographic findings did not exclude the possibility of further hearing loss.

[The role of conjugal relations in the abuse and neglect of children: towards an ecological study]

The phenomenon of child abuse and neglect has always existed in Western society. Yet, it is only recently that clinicians and researchers have taken a serious look at these problems. This ever growing interest has come about from not only the stunning number of cases identified each year, but also by the extent and gravity of consequences observed among children. Several professionals interested by the issue have put forward a great number of etiological factors to try to explain abuse and neglect within the family unit. However, when assessing the proposed theoretical models (psychiatric/psychological, sociological, systemic), it appears that certain simple factors can play a large role, for instance the history behind parental development, the quality of marital relations, the child-parent relation, the stress and the extent of the social network, but none of these can clearly differentiate abusive families from non abusive families. It seems however that these different explicative factors would be even more valuable if they were considered in interaction rather than taken individually. Inspired by the ecological framework proposed by Bronfenbrenner (1977, 1979), Belsky (1980, 1984) as well as Cicchetti and Rizley (1981) have also developed a model that simultaneously takes into account all of these factors and their interaction.

Epstein-Barr virus polymorphic B-cell lymphoma associated with leukemia and with congenital immunodeficiencies

Polymorphic B-cell lymphoma seen in four patients with congenital immunodeficiencies and in two patients with leukemia receiving chemotherapy was associated with the Epstein-Barr virus (EBV). The tumors had characteristic histologic features: they were polymorphic consisting of a mixture of lymphoblasts and differentiated cells including plasma cells, and areas of hemorrhagic necrosis were prominent. The tumors were either polyclonal, monoclonal, or multiclonal. Patients with congenital immunodeficiencies who developed these tumors died despite radiotherapy, corticosteroids plus acyclovir, or a combination of intravenous (IV) immunoglobulins and alpha 2 interferon. Patients with leukemia recovered when immunosuppressive drugs were discontinued and leukemia has not recurred over a period of 2 and 4 years, respectively, in the two patients.

Reduced pituitary volume in children with short stature: clinical and radiological correlates

A retrospective evaluation of 80 cases of growth retardation evaluated at the Hôpital Sainte-Justine of Montreal has revealed that 20 of them (25%; 15 boys and 5 girls) had a reduction of pituitary volume as revealed by high-resolution CT scanning of the pituitary gland. Of these patients, 8 had complete growth hormone (GH) deficiency, as evaluated by arginine infusion and L-Dopa-propranolol testing and nocturnal blood sampling, and 3 had GH neurosecretory dysfunction. Five patients had combined or multiple hormonal deficiencies. A statistically significant correlation was found between nocturnal plasma GH values and pituitary volumes. From this study it can be concluded that reduced pituitary volume is a frequent finding in growth-retarded children with hypopituitarism.

Computed tomography brain scans in long term survivors of childhood acute lymphoblastic leukemia

There have been varying frequencies cited for the occurrence of abnormal brain CT scans in leukemic patients and conflicting evidence about the significance of these abnormalities and their relationship to sanctuary therapy. Our study of CT brain scans in 26 long survivors of acute lymphoblastic leukemia showed an overall prevalence of 35% abnormal scans. There was no statistically significant difference between the number of abnormal scans in patients given radiotherapy as part of their CNS prophylaxis and those receiving only intrathecal methotrexate. Because the children in each treatment group were evenly matched with respect to other treatment variables possibly relevant to the causation of abnormal brain scans, a strong case is made for more rigorous design of such studies, preferably in a prospective fashion, looking simultaneously at other parameters of brain structure and function.

Fate of the plasma membrane of Saccharomyces cerevisiae during cell rupture

Intact and homogenized yeast cells were studied in thin sections in the electron microscope to determine the fate of the plasma membrane during fractionation. Intact cells possess a unit-membrane plasma membrane closely appressed to the cell wall. After even slight physical damage following limited homogenization in dilute buffer, the plasma membrane collapses away from the wall while the intra-cytoplasmic membranes (ER, vacuolar, nuclear, mitochondrial) dilate and vesiculate. With prolonged homogenization, the plasma membrane fragments and vesiculates and becomes indistinguishable from the remains of the other membranes. Washed wall fractions consist of wall fragments with entrapped vesicles derived from all cellular membranes. Exhaustive digestion of the wall fraction with snail gut enzymes liberates some of the trapped vesicles and results in an undigested, non-membranous, inner layer of wall partially contaminated with outer wall material. Polyacrylamide gel electrophoresis indicates that proteins of the wall "membranes" are partially of mitochondrial origin.