Mandibular Advancement vs CPAP for Blood Pressure Reduction in Patients With Obstructive Sleep Apnea

BACKGROUND

Hypertension guidelines recommend diagnosis and treatment of obstructive sleep apnea (OSA) in patients with hypertension. The mandibular advancement device (MAD) is an oral appliance therapy for patients who decline or cannot tolerate continuous positive airway pressure (CPAP).

OBJECTIVES

We compared the relative effectiveness of MAD vs CPAP in reducing 24-hour ambulatory blood pressure (BP).

METHODS

In an investigator-initiated, randomized, noninferiority trial (prespecified margin 1.5 mm Hg), 321 participants aged ≥40 years with hypertension and increased cardiovascular risk were recruited at 3 public hospitals for polysomnography. Of these, 220 participants with moderate-to-severe OSA (apnea-hypopnea index ≥15 events per hour) were randomized to either MAD or CPAP (1:1). The primary outcome was the difference between the 24-hour mean arterial BP at baseline and 6 months.

RESULTS

Compared with baseline, the 24-hour mean arterial BP decreased by 2.5 mm Hg (P = 0.003) at 6 months in the MAD group, whereas no change was observed in the CPAP group (P = 0.374). The between-group difference was -1.6 mm Hg (95% CI: -3.51 to 0.24, noninferiority P < 0.001). The MAD group demonstrated a larger between-group reduction in all secondary ambulatory BP parameters compared with the CPAP group, with the most pronounced effects observed in the asleep BP parameters. Both the MAD and CPAP improved daytime sleepiness, with the between-group difference similar (P = 0.384). There were no between-group differences in cardiovascular biomarkers.

CONCLUSIONS

MAD is noninferior to CPAP for reducing 24-hour mean arterial BP in participants with hypertension and increased cardiovascular risk. (Cardiosleep Research Program on Obstructive Sleep Apnea, Blood Pressure Control and Maladaptive Myocardial Remodeling-Non-inferiority Trial [CRESCENT]; NCT04119999).

Mandibular advancement device versus CPAP in lowering 24-hour blood pressure in patients with obstructive sleep apnoea and hypertension: the CRESCENT trial protocol

INTRODUCTION

Although treatment of obstructive sleep apnoea (OSA) using continuous positive airway pressure (CPAP) reduces blood pressure (BP), adherence to CPAP is often suboptimal. A mandibular advancement device (MAD) is a guideline-endorsed alternative therapy for OSA. Still, there is limited evidence on the relative efficacy between MAD and CPAP on BP reduction. We evaluate whether treatment of moderate-to-severe OSA using MAD can improve BP and other health-related outcomes compared with CPAP.

METHODS AND ANALYSIS

This is a randomised, controlled, non-inferiority trial conducted. We will recruit 220 Asians with a history of hypertension and high cardiovascular risk for an overnight polysomnography screening. Those with moderate-to-severe OSA (apnoea-hypopnoea index ≥15 events/hour) will be randomised to treatment with either MAD or CPAP in a 1:1 ratio. Stratified by age (60 vs <60 years old), body mass index (25 vs <25 kg/m²) and apnoea-hypopnoea index (30 vs <30 events/hour), an adaptive randomisation scheme with permuted blocks constructed in real-time is implemented to restrict imbalance. The overall study duration is 12 months. The primary endpoint is the 24-hour mean arterial BP difference between baseline and 6-month follow-up. The secondary endpoints include other measures of ambulatory BP monitoring, arrhythmia based on a 4-day electrocardiographic monitoring, biomarker and proteomic analysis, cardiovascular magnetic resonance-derived myocardial fibrosis and remodelling and quality-of-life questionnaires. Recruitment began in October 2019 and ended in December 2022. Comparison between MAD and CPAP will be performed using covariance (ANCOVA) analysis of the changes in 24-hour mean arterial BP while adjusting for the baseline 24-hour mean arterial BP. We will compare the 95% CIs around the treatment difference point estimate with the prespecified non-inferiority margin (1.5 mm Hg). If the upper limit of the 95% CI is <1.5 mm Hg and crosses 0, non-inferiority of the MAD relative to CPAP will be established.

ETHICS AND DISSEMINATION

The Domain Specific Review Board-C, National Healthcare Group under approved the study protocol (NHG DSRB Ref: 2019/00359, approved on 28 August 2019). Study findings will be disseminated to various local, national, and international audiences through abstract presentations and publication in peer-reviewed journals.

TRIAL REGISTRATION NUMBER

NCT04119999.

Lipid goal attainment and prescription behavior in asian patients with acute coronary syndromes: experience from a tertiary hospital

Lipid goal attainment studies in Asian patients with acute coronary syndrome (ACS) are limited. The objectives of this study were to determine low-density lipoprotein cholesterol (LDL-C) goal attainment rate at 4 months, and to examine prescription behavior influencing lipid goal attainment in Asian patients with ACS. A retrospective analysis of 267 patients with ACS was performed. The mean follow-up duration was 41.2±10.7 months. LDL-C goal attainment rate was highest at 4 months (36.7%) but declined progressively throughout follow-up. More than 85% of patients were discharged with equipotent statin dose of 2 (equivalent to simvastatin 20 mg) or less. In patients who did not attain LDL-C goals, the statin dose remained low throughout follow-up because of a lack in responsive dose titration. Aggressive lipid-lowering therapy should be initiated early to improve goal attainment in these high-risk patients.

Sequence and analysis of chromosome 1 of the plant Arabidopsis thaliana

The genome of the flowering plant Arabidopsis thaliana has five chromosomes. Here we report the sequence of the largest, chromosome 1, in two contigs of around 14.2 and 14.6 megabases. The contigs extend from the telomeres to the centromeric borders, regions rich in transposons, retrotransposons and repetitive elements such as the 180-base-pair repeat. The chromosome represents 25% of the genome and contains about 6,850 open reading frames, 236 transfer RNAs (tRNAs) and 12 small nuclear RNAs. There are two clusters of tRNA genes at different places on the chromosome. One consists of 27 tRNA(Pro) genes and the other contains 27 tandem repeats of tRNA(Tyr)-tRNA(Tyr)-tRNA(Ser) genes. Chromosome 1 contains about 300 gene families with clustered duplications. There are also many repeat elements, representing 8% of the sequence.

A gene encoding a novel multidomain beta-1,4-mannanase from Caldibacillus cellulovorans and action of the recombinant enzyme on kraft pulp

Genomic walking PCR was used to obtained a 4,567-bp nucleotide sequence from Caldibacillus cellulovorans. Analysis of this sequence revealed that there were three open reading frames, designated ORF1, ORF2, and ORF3. Incomplete ORF1 encoded a putative C-terminal cellulose-binding domain (CBD) homologous to members of CBD family IIIb, while putative ORF3 encoded a protein of unknown function. The putative ManA protein encoded by complete manA ORF2 was an enzyme with a novel multidomain structure and was composed of four domains in the following order: a putative N-terminal domain (D1) of unknown function, an internal CBD (D2), a beta-mannanase catalytic domain (D3), and a C-terminal CBD (D4). All four domains were linked via proline-threonine-rich peptides. Both of the CBDs exhibited sequence similarity to family IIIb CBDs, while the mannanase catalytic domain exhibited homology to the family 5 glycosyl hydrolases. The purified recombinant enzyme ManAd3 expressed from the cloned catalytic domain (D3) exhibited optimum activity at 85 degrees C and pH 6.0 and was extremely thermostable at 70 degrees C. This enzyme exhibited high specificity with the substituted galactomannan locust bean gum, while more substituted galacto- and glucomannans were poorly hydrolyzed. Preliminary studies to determine the effect of the recombinant ManAd3 and a recombinant thermostable beta-xylanase on oxygen-delignified Pinus radiata kraft pulp revealed that there was an increase in the brightness of the bleached pulp.

Cloning of the xynB gene from Dictyoglomus thermophilum Rt46B.1 and action of the gene product on kraft pulp

A two-step PCR protocol was used to identify and sequence a family 11 xylanase gene from Dictyoglomus thermophilum Rt46B.1. Family 11 xylanase consensus fragments (GXCFs) were amplified from Rt46B.1 genomic DNA by using different sets of consensus PCR primers that exhibited broad specificity for conserved motifs within fungal and/or bacterial family 11 xylanase genes. On the basis of the sequences of a representative sample of the GXCFs a single family 11 xylanase gene (xynB) was identified. The entire gene sequence was obtained in the second step by using genomic walking PCR to amplify Rt46B.1 genomic DNA fragments upstream and downstream of the xynB GXCF region. The putative XynB peptide (M(r), 39,800) encoded by the Rt46B.1 xynB open reading frame was a multidomain enzyme comprising an N-terminal catalytic domain (M(r), 22,000) and a possible C-terminal substrate-binding domain (M(r), 13,000) that were separated by a short serine-glycine-rich 23-amino-acid linker peptide. Seven xylanases which differed at their N and C termini were produced from different xynB expression plasmids. All seven xylanases exhibited optimum activity at pH 6.5. However, the temperature optima of the XynB xylanases varied from 70 to 85 degrees C. Pretreatment of Pinus radiata and eucalypt kraft-oxygen pulps with XynB resulted in moderate xylan solubilization and a substantial improvement in the bleachability of these pulps.

Cutaneous Rosai-Dorfman disease presenting as a suspicious breast mass

Cutaneous Rosai-Dorfman disease in a male patient presented as a clinically malignant left breast mass. The intra-operative frozen section indicated a benign inflammatory lesion and a simple excision was performed. The disease was apparently limited to the skin and subcutis of the left breast with no lymph nodes or other organs involvement. While the lesion demonstrated the characteristic morphology of Rosai-Dorfman disease, the diagnosis of granulomatous mastitis, epithelioid sarcoma and other cutaneous xanthohistiocytic proliferations were considered. In the absence of lymphadenopathy, a high index of diagnostic awareness is required to recognize the uncommon, solitary cutaneous Rosai-Dorfman disease.

Prenatal nicotine exposure increased duration of nicotine-induced analgesia in adult rats

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The effect of nifedipine and verapamil on nicotine-induced antinociception in rats

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Modulation of nicotine-induced analgesia by calcium agonist and antagonist in adult rats

The involvement of calcium in nicotine-induced analgesia in male rats was explored using the tail-flick test. A single dose of nicotine (1 mg/kg SC) produced a maximal effect on tail-flick latency (15 s) within 8-10 min, which lasted for 4 min. Pretreatment with the calcium chelator, EDTA (250 microM/kg SC four injections at 15 min intervals), before the single dose of nicotine accelerated the onset and prolonged the duration of the nicotine-induced analgesia. The maximal effect on tail-flick latency occurred within 2 min and lasted for 10-20 min. Conversely, pretreatment with calcium chloride (1.5 mM/kg IP) attenuated nicotine-induced analgesia. It is suggested that nicotine may exert its antinociceptive effects via modulation of calcium fluxes across the neural membrane.

Nicotine-induced analgesia in rats: the role of calcium and the diversity of responders and nonresponders

Following a single dose of nicotine, (NIC, 1 mg/kg s.c.), 60% of tested rats revealed significant antinociception as measured by the tail-flick (TF) test, and were classified as responders, with those in which TF latencies did not change, nonresponders. The following experiments were carried out one week later. In nonresponders, pretreatment with ethylenediaminetetraacetic acid (EDTA, 250 microM/kg s.c. four times every 15 min) followed by 1 mg NIC, produced significant analgesia in 50% of rats, to the same magnitude as did nicotine alone (1 mg) in responders. The other 50% of rats which failed to respond to EDTA pretreatment, all revealed similar analgesia following the higher dose of NIC (1.5 mg/kg s.c.), with similar side effects, as generally observed in responders. In responders, pretreatment with CaCl2 (1.5 mM/kg s.c.) completely abolished NIC (1 mg/kg s.c.)--induced analgesia in all rats. Our data provide stronger evidence and a further verification that EDTA potentiates, whereas CaCl2 completely abolishes, nicotine-induced analgesia in rats; supporting our hypothesis of the involvement of calcium ions in this effect.