Home (Level 2) polysomnography is feasible in children with suspected sleep disorders

AIM

To audit the feasibility and patient experience of home polysomnography (sleep study) for the investigation of a sleep disorder in children.

METHODS

The signal quality and outcomes of a Level 2 (home) polysomnography in young people undergoing investigation between September 2020 and January 2021 in a single centre was reviewed. A successful home polysomnogram was defined as a study with ≥6 h of sleep and all channels (EEG, thoraco-abdominal bands, calculated airflow, and pulse oximetry) present for at least 90% of the study time. Feedback from the guardian and young person was collected following the study using a questionnaire.

RESULTS

Fifty-five patients, aged 4 months to 18 years, were included. A successful polysomnogram, on the first attempt, was achieved for 48/55 (87%) subjects. There were no differences in success when accounting for neurodevelopmental conditions, OSA severity or age. The majority (76%) of guardians felt that their child slept the same or better than normal and only 12% found having the study conducted at home difficult. Following the study, only 8% would have preferred a hospital sleep study in retrospect.

CONCLUSIONS

Home polysomnography produced a technically adequate study for the majority of subjects. Most families also found the experience of having a home sleep study to be positive. These data support the use of home sleep studies as an alternative to an in-patient sleep study, in appropriate circumstances, for young people undergoing investigation of a sleep disorder.

Prediction and prevention of early-onset pre-eclampsia: impact of aspirin after first-trimester screening

OBJECTIVE

To examine the effect of a combination of screening and treatment with low-dose aspirin on the prevalence of early-onset pre-eclampsia (PE).

METHODS

This was a retrospective analysis of two consecutive cohorts of women screened for early PE. The first cohort was observed to determine whether algorithms developed to screen for PE at 11 to 13 + 6 weeks' gestation could be applied to our population. High-risk women in the second cohort were advised on their risk and offered aspirin (150 mg at night), with treatment starting immediately after screening. The prevalence of early PE and the proportion of women with PE delivering at 34-37 weeks' gestation were compared between the cohorts.

RESULTS

In the observational and interventional cohorts, 3066 and 2717 women, respectively, were screened. There were 12 (0.4%) cases of early PE in the observational cohort and one (0.04%) in the interventional cohort (P < 0.01). Among all women with PE delivering before 37 weeks, 25 (0.83%) were in the observational cohort and 10 (0.37%) in the interventional cohort (P = 0.03).

CONCLUSIONS

A strategy of first-trimester screening for early PE coupled with prescription of aspirin to the high-risk group appears to be effective in reducing the prevalence of early PE.

Binding to histone of an anomalous IgG from patients with SLE and drug-induced lupus

The mechanism of attachment of circulating immune complexes (CIC) to glomerular basement membranes (GBM) in systemic lupus erythematosus (SLE) has not yet been elucidated. One difficulty is that CIC must be strongly cationic for such deposition to occur, which is opposite to the anionic nature of putative DNA-anti-DNA immune complexes (DNA-IC). The strongly cationic histone has been proposed as a potential "planted antigen"; it would decorate the GBM to function as a ligand for DNA in the DNA-IC. However, DNA-IC, aggregated IgG and most of the IgG "anti-histone antibodies" in SLE patient sera bind to histone on a solid phase not through DNA, but through the Fcgamma. Here, we investigated the nature of the anti-histone "antibody" in sera of 18 patients with SLE and 57 with drug-induced lupus (DIL). The binding to nucleosomes of IgG from these patients was mainly pepsin-resistant and F(ab')(2)-dependent, whereas the binding to histone was mainly pepsin-sensitive and Fcgamma-dependent. Surprisingly, after molecular sieving of 12 of these sera, the pepsin-sensitive histone-binding IgG was located mainly in the 150-kDa monomeric IgG peak. The binding to nucleosomes was only in the 150-kDa peak. These findings are consistent with the existence of an anomalous IgG in SLE and DIL sera, capable, like aggregated IgG, DNA-IC and other CIC, of binding to histone-decorated structures. We propose that this anomalous IgG plays an essential role in the pathogenesis of lupus nephritis and other related inflammatory conditions. These observations also explain the large discrepancies in the reports on anti-histone autoantibodies in autoimmune conditions.

Mouse alpha1-syntrophin binding to Grb2: further evidence of a role for syntrophin in cell signaling

Syntrophins have been proposed to serve as adapter proteins. Syntrophins are found in the dystrophin glycoprotein complex (DGC); defects in the constituents of this complex are linked to various muscular dystrophies. Blot overlay experiments demonstrate that alpha-dystroglycan, beta-dystroglycan, and syntrophins all bind Grb2, the growth factor receptor bound adapter protein. Mouse alpha1-syntrophin sequences were produced as chimeric fusion proteins in bacteria and found to also bind Grb2 in a Ca2+-independent manner. This binding was localized to the proline rich sequences adjacent to and overlapping with the N-terminal pleckstrin homology domain (PH1). Grb2 bound syntrophin with an apparent KD of 563 +/- 15 nM. Grb2-C-SH3 domain bound syntrophin with slightly higher affinity than Grb2-N-SH3 domain. Crk-L, an SH2/SH3 protein of similar domain structure but different specificity, does not bind these syntrophin sequences.

Characterization of the beta-dystroglycan-growth factor receptor 2 (Grb2) interaction

The beta-dystroglycan/Grb2 interaction was investigated and a proline-rich region within beta-dystroglycan that binds Grb2-src homology 3 domains identified. We used surface plasmon resonance (SPR), fluorescence analysis, and solid-phase binding assay to measure the affinity constants between Grb2 and the beta-dystroglycan cytoplasmic tail. Analysis of the data obtained from SPR reveals a high-affinity interaction (K(D) approximately 240 nM) between Grb2 and the last 20 amino acids of the beta-dystroglycan carboxyl-terminus, which also contains a dystrophin-binding site. A similar K(D) value (K(D) approximately 280 nM) was obtained by solid-phase binding assay and in solution by fluorescence. Both Grb2-SH3 domains bind beta-dystroglycan but the N-terminal SH3 domain binds with an affinity approximately fourfold higher than that of the C-terminal SH3 domain. The Grb2-beta-dystroglycan interaction was inhibited by dystrophin in a range of concentration of 160-400 nM. These data suggest a highly regulated and dynamic dystrophin/dystroglycan complex formation and that this complex is involved in cell signaling.

Chronic disease self-management: improving health outcomes

Chronic disease has become pandemic in the United States, and estimates are that it will affect 148 million people by the year 2030. Patients with chronic illnesses cost the health care system over three times more than individuals without chronic conditions. The US Department of Veterans' Affairs (VA) Sunshine HealthCare Network, composed of VA health care facilities in Florida and Puerto Rico, recognized that the needs of its increasing number of veterans with chronic diseases were unmet by traditional medical interventions. The Network implemented a chronic disease self-management pilot program to evaluate its value for the veteran population. Results of the pilot indicate that this program will make a positive, lasting change in the health status and quality of life for veterans with chronic disease.

Circulating anticentromere CENP-A and CENP-B antibodies in patients with diffuse and limited systemic sclerosis, systemic lupus erythematosus, and rheumatoid arthritis

OBJECTIVE

To determine the disease sensitivity and specificity of testing for autoantibodies against 2 of the 3 main human centromere antigenic components, CENP-A and CENP-B (recombinant, expressed in baculovirus).

METHODS

ELISA with CENP-A and CENP-B antigens were used to test 45 sera showing a centromere pattern by immunofluorescence (IFA) and sera from 96 patients with systemic sclerosis (SSc), subdivided into diffuse (dSSc) and limited (lSSc) forms. For controls, the same tests were performed on sera from 100 patients with rheumatoid arthritis (RA), 100 with systemic lupus erythematosus (SLE), and 50 random blood donors. Sera from all the patients with SSc were also tested for the presence of anti-Scl70 antibody by ELISA (bovine antigen), and for pattern and titer by IFA (HEp-2 cells).

RESULTS

Of the 45 IFA positive sera, 93% were positive for anti-CENP-A and 91% for anti-CENP-B. There was a very good quantitative correlation between the antibody levels against these 2 centromere components (r = 0.597; p<0.001). Anti-CENP-A and B were found in 48% of patients with lSSc, and in 11% and 9%, respectively, of those with dSSc. The difference in the frequency of anti-CENP-A between the 2 patient groups was significant (chi-squared, p<0.001). Similar levels of anticentromere staining pattern by IFA were observed for these 2 groups. Anti-Scl70 was elevated in 8% of lSSc and 25% of dSSc patients; this difference was also significant (chi-squared, p = 0.02). Neither CENP-A nor CENP-B reacted with IgG from SSc patients containing anti-Scl70. The frequency of abnormal levels in patients with SLE and RA was, respectively, 11% and 3% for anti-CENP-A and 4% and 3% for anti-CENP-B. The reaction of IgG from SLE and RA patients with CENP-A was not inhibited by histone H3, i.e., it was not due to recognition of the histone-like domain in CENP-A. Thus, when 96 SSc patients were compared to 200 patients with RA and SLE, the disease specificity of anti-CENP-A and B was 93% and 96.5%, respectively.

CONCLUSION

In addition to IFA, ELISA tests for CENP-A and CENP-B yield results with similar sensitivity and specificity for the diagnosis of SSc. CENP-A and CENP-B are primarily associated with lSSc. In SSc the autoantibody response is directed simultaneously and with similar amplitude against these 2 components of the centromere structure, whereas in other autoimmune diseases the response is directed mainly against one of the 2 components.

A high-density integrated genetic linkage and radiation hybrid map of the laboratory rat

The laboratory rat (Rattus norvegicus) is a key animal model for biomedical research. However, the genetic infrastructure required for connecting phenotype and genotype in the rat is currently incomplete. Here, we report the construction and integration of two genomic maps: a dense genetic linkage map of the rat and the first radiation hybrid (RH) map of the rat. The genetic map was constructed in two F2 intercrosses (SHRSP x BN and FHH x ACI), containing a total of 4736 simple sequence length polymorphism (SSLP) markers. Allele sizes for 4328 of the genetic markers were characterized in 48 of the most commonly used inbred strains. The RH map is a lod >/= 3 framework map, including 983 SSLPs, thereby allowing integration with markers on various genetic maps and with markers mapped on the RH panel. Together, the maps provide an integrated reference to >3000 genes and ESTs and >8500 genetic markers (5211 of our SSLPs and >3500 SSLPs developed by other groups). [Bihoreau et al. (1997); James and Tanigami, RHdb (http:www.ebi.ac.uk/RHdb/index.html); Wilder (http://www.nih.gov/niams/scientific/ratgbase); Serikawa et al. (1992); RATMAP server (http://ratmap.gen.gu.se)] RH maps (v. 2.0) have been posted on our web sites at http://goliath.ifrc.mcw.edu/LGR/index.html or http://curatools.curagen.com/ratmap. Both web sites provide an RH mapping server where investigators can localize their own RH vectors relative to this map. The raw data have been deposited in the RHdb database. Taken together, these maps provide the basic tools for rat genomics. The RH map provides the means to rapidly localize genetic markers, genes, and ESTs within the rat genome. These maps provide the basic tools for rat genomics. They will facilitate studies of multifactorial disease and functional genomics, allow construction of physical maps, and provide a scaffold for both directed and large-scale sequencing efforts and comparative genomics in this important experimental organism.

Testing the global-slowing hypothesis: are alcohol's effects on human performance process-specific or task-general?

In an interesting recent meta-analysis, Maylor and Rabbitt (1993) suggested that alcohol's effects on human performance may not be process- or stage-specific, but reflect a general, undifferentiated, cognitive slowing. According to this view, performance is globally slowed by a constant multiplicative fraction (b), such that the longer a process takes without alcohol on board (a -), the more it will be slowed by alcohol (a +). In summary: RTa+ = b b (RTa-). In this sense, the effects of alcohol are determined simply by the duration of a process or stage--not by its function or content--and attempts to map the effects of alcohol to specific cognitive operations are essentially futile. This global-slowing hypothesis entails, then, (i) that the function relating RTa+ to RTa- will be linear and increasing; (ii) that the value of b will be significantly greater than 1.0; and (iii) that all experimental factors which increase the complexity (hence, duration) of a task or stage will interact with alcohol. In this study we tested the global-slowing hypothesis directly using fixed set, varied set and concurrent sets item-recognition paradigms. All three tasks showed convincing additivity between alcohol and other key experimental factors which affect response latency (e.g., setsize, response type); there was no hint of any of the spectrum of significant interactions predicted by the global-slowing hypothesis. A meta-analysis of varied set latencies, analogous to Maylor and Rabbitt's, yielded a reasonably linear alcohol/no-alcohol function, but with a slope constant (b) less than 1.0. In all, the data provided little support for the global-slowing hypothesis.

Effect of vasopressin on myocardial capillary recruitment and coronary blood flow in the anesthetized rabbit

The effects of infusion of arginine vasopressin (20 mU.kg-1.min-1) on coronary blood flow and the proportion of the coronary microvasculature perfused was studied in rabbit myocardium. Fluorescein isothiocyanate--dextran was injected into anesthetized open-chest rabbits to identify the perfused vessels and an alkaline phosphatase stain was employed to locate the total microvasculature. Coronary blood flow (radioactive microspheres) was studied in separate groups of rabbits. Vasopressin infusion caused bradycardia (243 +/- 19 to 165 +/- 22 beats/min, mean +/- SD) and an increase in mean blood pressure (92 +/- 18 to 104 +/- 12 mmHg) (1 mmHg = 133.32 Pa). Coronary blood flow decreased significantly with vasopressin from 209 +/- 68 to 97 +/- 36 mL.min-1.100 g-1. The proportion of the arteriolar bed per millimeter squared perfused decreased significantly after vasopressin from 54 +/- 13 to 44 +/- 21%, while the percentage of capillaries per millimeter squared increased significantly from 57 +/- 6 to 67 +/- 11%. There were no subepicardial versus subendocardial differences in any measured parameter. Thus, both coronary blood flow and the proportion of the arteriolar bed perfused decreased with vasopressin. However, compensation occurred in that the proportion of capillaries perfused increased. This indicated an independent level of control of the coronary arteriolar and capillary beds. These microvascular changes may help to maintain oxygen supply-demand balance with vasopressin in the heart.