Clinical performance, safety, and patient-reported outcomes of an active osseointegrated bone-conduction hearing implant system at 24-month follow-up

PURPOSE

To investigate 2-year post-operative hearing performance, safety, and patient-reported outcomes of hearing-impaired adults treated with the Osia® 2 System, an active osseointegrated bone-conduction hearing implant that uses piezoelectric technology.

METHODS

A prospective, multicenter, open-label, single-arm, within-subject clinical study conducted at three tertiary referral clinical centers located in Melbourne, Sydney and Hong Kong. Twenty adult recipients of the Osia 2 System were enrolled and followed up between 12 and 24 months post-implantation: 17 with mixed or conductive hearing loss and 3 with single-sided sensorineural deafness. Safety data, audiological thresholds, speech recognition thresholds in noise, and patient-reported outcomes were collected and evaluated. In addition, pre-and 6-month post-implantation data were collected retrospectively for this recipient cohort enrolled into the earlier study (ClinicalTrials.gov NCT04041700).

RESULTS

Between 6- and 24-month follow-up, there was no statistically significant change in free-field hearing thresholds or speech reception thresholds in noise (p =  > 0.05), indicating that aided improvements were maintained up to 24 months of follow-up. Furthermore, improvements in health-related quality of life and daily hearing ability, as well as clinical and subjective measures of hearing benefit remained stable over the 24-month period. No serious adverse events were reported during extended follow-up.

CONCLUSIONS

These study results provide further evidence to support the longer term clinical safety, hearing performance, and patient-related benefits of the Osia 2 System in patients with either a conductive hearing loss, mixed hearing loss, or single-sided sensorineural deafness.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT04754477. First posted: February 15, 2021.

Characterisation of de novo mutations in the C-terminal domain of proprotein convertase subtilisin/kexin type 9

Proprotein convertase subtilisin/kexin type 9 (PCSK9) promotes the degradation of the hepatic low-density lipoprotein receptor (LDL-R) and is therefore a prominent therapeutic target for reducing LDL-cholesterol. The C-terminal domain of PCSK9 is unlikely to be involved in a direct extracellular interaction with the LDL-R. We probed the importance of the C-terminus for the degradation of the LDL-R by designing seven de novo mutants of PCSK9 that fill potential druggable cavities. The mutants were tested for their ability to diminish LDL uptake in human HepG2 cells and for affinity towards a calcium independent mutant of the EGF(A) domain of the human LDL-R. The later was done by a newly developed surface plasmon resonance-based assay format. We identified three mutant proteins (G517R, V610R and V644R) with decreased ability to block LDL uptake into HepG2 cells. These mutations define areas outside the direct interaction area between PCSK9 and the LDL-R that could be targeted to inhibit the PCSK9 triggered degradation of the LDL-R. We also describe the mechanistic rationalisation of the affinity changes seen with the natural occurring human D374Y (gain of function) mutation causing severe hypercholesterolaemia. The action of this mutant is due to a significantly decreased dissociation rate constant, whereas the mutation does not affect the association rate constant.

ACAT-selective and Nonselective DGAT1 Inhibition

Acyl-coenzyme A: cholesterol O-Acyltransferase (ACAT) and Acyl-coenzyme A: diacylglycerol O-acyltransferase (DGAT) enzymes play important roles in synthesizing neutral lipids, and inhibitors of these enzymes have been investigated as potential treatments for diabetes and other metabolic diseases. Administration of a Acyl-coenzyme A: diacylglycerol O-acyltransferase 1 (DGAT1) inhibitor with very limited cellular selectivity over ACAT resulted in significant adrenocortical degenerative changes in dogs. These changes included macrosteatotic vacuolation associated with adrenocyte cell death in the zonae glomerulosa and fasciculata and minimal to substantial mixed inflammatory cell infiltration and were similar to those described previously for some ACAT inhibitors in dogs. In the mouse, similar but only transient adrenocortical degenerative changes were seen as well as a distinctive nondegenerative reduction in cortical fine vacuolation. In the marmoset, only the distinctive nondegenerative reduction in cortical fine vacuolation was observed, suggesting that the dog, followed by the mouse, is the most sensitive species for cortical degeneration. Biochemical analysis of adrenal cholesterol and cholesteryl ester indicated that the distinctive reduction in cortical fine vacuolation correlated with a significant reduction in cholesteryl ester in the mouse and marmoset, whereas no significant reduction in cholestryl ester, but an increase in free cholesterol was observed in dogs. Administration of a DGAT1 inhibitor with markedly improved selectivity over ACAT to the marmoset and the mouse resulted in no adrenal pathology at exposures sufficient to cause substantial DGAT1 but not ACAT inhibition, thereby implicating ACAT rather than DGAT1 inhibition as the probable cause of the observed adrenal changes. Recognizing that the distinctive nondegenerative reduction in cortical fine vacuolation in the mouse could be used as a histopathological biomarker for an in vivo model of the more severe changes observed in dogs, the mouse has subsequently been used as a model to select DGAT1 inhibitors free of adrenocortical toxicity.

Improvement of psychic and somatic symptoms in adult patients with generalized anxiety disorder: examination from a duloxetine, venlafaxine extended-release and placebo-controlled trial

BACKGROUND

This study examined the efficacy and tolerability of duloxetine and venlafaxine extended-release (XR) treatment for generalized anxiety disorder (GAD), with a secondary focus on psychic and somatic symptoms within GAD.

METHOD

The design was a 10-week, multi-center, double-blind placebo-controlled study of duloxetine (20 mg or 60-120 mg once daily) and venlafaxine XR (75-225 mg once daily) treatment. Efficacy was measured using the Hamilton Anxiety Rating Scale (HAMA), which includes psychic and somatic factor scores. Tolerability was measured by occurrence of treatment-emergent adverse events (TEAEs) and discontinuation rates.

RESULTS

Adult out-patients (mean age 42.8 years; 57.1% women) with DSM-IV-defined GAD were randomly assigned to placebo (n=170), duloxetine 20 mg (n=84), duloxetine 60-120 mg (n=158) or venlafaxine XR 75-225 mg (n=169) treatment. Each of the three active treatment groups had significantly greater improvements on HAMA total score from baseline to endpoint compared with placebo (p=0.01-0.001). For the HAMA psychic factor score, both duloxetine treatment arms and venlafaxine XR demonstrated significantly greater improvement compared with placebo (p=0.01-0.001). For the HAMA somatic factor score, the mean improvement in the duloxetine 60-120 mg and venlafaxine XR groups was significantly greater than placebo (p0.05 and p0.01 respectively), whose mean improvement did not differ from the duloxetine 20 mg group (p=0.07). Groups did not differ in study discontinuation rate due to adverse events.

CONCLUSIONS

Duloxetine and venlafaxine treatment were each efficacious for improvement of core psychic anxiety symptoms and associated somatic symptoms for adults with GAD.

Secretory Phospholipase A 2 Group V

Objective— To study the distribution of group V secretory phospholipase A 2 (sPLA 2 ) in human and mouse lesions and compare its expression by human vascular cells, its activity toward lipoproteins, and the interaction with arterial proteoglycans (proteoglycans) with those of sPLA 2 -IIA. In addition, we also investigated the effect of a Western diet and lipopolysaccharide challenge on the aortic expression of these enzymes in mouse models.

Methods and Results— Immunohistochemistry showed sPLA 2 -V in human and mouse lesions to be associated with smooth muscle cells and also surrounding foam cells in lipid core areas. mRNA of the enzyme was expressed in human lesions and human vascular cells, supporting the immunohistochemistry data. sPLA 2 -V but not sPLA 2 -IIA was active on lipoproteins in human serum. The association with proteoglycans enhanced 2- to 3-fold sPLA 2 -V activity toward low-density lipoproteins but not that of the group IIA enzyme. Experiments in mouse models showed that treatment with a Western diet induced expression of sPLA 2 -V but not that of sPLA 2 -IIA in aorta. On the other hand, lipopolysaccharide-induced acute inflammation augmented the expression of sPLA 2 -IIA but not that of sPLA 2 -V.

Conclusions— These results indicate that these phospholipases could have different roles in atherosclerosis.

Liver-directed overexpression of mitochondrial glycerol-3-phosphate acyltransferase results in hepatic steatosis, increased triacylglycerol secretion and reduced fatty acid oxidation

Glycerol-3-phosphate acyltransferase (GPAT) catalyzes the first committed step in triacylglycerol (TAG) and phospholipid biosynthesis. GPAT activity has been identified in both ER and mitochondrial subcellular fractions. The ER activity dominates in most tissues except in liver, where the mitochondrial isoform (mtGPAT) can constitute up to 50% of the total activity. To study the in vivo effects of hepatic mtGPAT overexpression, mice were transduced with adenoviruses expressing either murine mtGPAT or a catalytically inactive variant of the enzyme. Overexpressing mtGPAT resulted in massive 12- and 7-fold accumulation of liver TAG and diacylglycerol, respectively but had no effect on phospholipid or cholesterol ester content. Histological analysis showed extensive lipid accumulation in hepatocytes. Furthermore, mtGPAT transduction markedly increased adipocyte differentiation-related protein and stearoyl-CoA desaturase-1 (SCD-1) in the liver. In line with increased SCD-1 expression, 18:1 and 16:1 in the hepatic TAG fraction increased. In addition, mtGPAT overexpression decreased ex vivo fatty acid oxidation, increased liver TAG secretion rate 2-fold, and increased plasma TAG and cholesterol levels. These results support the hypothesis that increased hepatic mtGPAT activity associated with obesity and insulin resistance contributes to increased TAG biosynthesis and inhibition of fatty acid oxidation, responses that would promote hepatic steatosis and dyslipidemia.

A proteomic study of the apolipoproteins in LDL subclasses in patients with the metabolic syndrome and type 2 diabetes

The exchangeable apolipoproteins present in small, dense LDL (sdLDL) and large, buoyant LDL subclasses were evaluated with a quantitative proteomic approach in patients with the metabolic syndrome and with type 2 diabetes, both with subclinical atherosclerosis and the B LDL phenotype. The analyses included surface-enhanced laser adsorption/ionization, time-of-flight mass spectrometry, and subsequent identification by mass spectrometry or immunoblotting and were carried out in LDL subclasses isolated by ultracentrifugation in deuterium oxide gradients with near physiological salt concentrations. The sdLDLs of both types of patients were enriched in apolipoprotein C-III (apoC-III) and were depleted of apoC-I, apoA-I, and apoE compared with matched healthy controls with the A phenotype. The LDL complexes formed in serum from patients with diabetes with the arterial proteoglycan (PG) versican were also enriched in apoC-III. In addition, there was a significant correlation between the apoC-III content in sdLDL in patients and the apparent affinity of their LDLs for arterial versican. The unique distribution of exchangeable apolipoproteins in the sdLDLs of the patients studied, especially high apoC-III, coupled with the augmented affinity with arterial PGs, may contribute to the strong association of the dyslipidemia of insulin resistance with increased risk for cardiovascular disease.

Lipoprotein fractionation in deuterium oxide gradients: a procedure for evaluation of antioxidant binding and susceptibility to oxidation

Oxidative modifications of lipoproteins appear to contribute to their atherogenicity. Very low and low density lipoproteins (VLDL and LDL) are protected against these modifications by antioxidants that can be incorporated in vivo or in vitro into the particles. We describe here ultracentrifugal procedures for isolation of VLDL and LDL that do not require subsequent dialysis or buffer equilibration. Lipoproteins were isolated in buffers with physiological ionic composition prepared in D2O (deuterium oxide). This allowed measurements of the content of antioxidants and of the susceptibility to oxidation of the isolated LDL without further manipulations. Conventional ultracentrifugal methods use high salt concentrations and require additional steps to eliminate them. This introduces uncertainties in the evaluation of antioxidant binding and on measurements of their effect on VLDL and LDL oxidation. With the method described, the composition of the isolated VLDL and LDL was indistinguishable from that of fractions isolated with KBr gradients. Also, the content of alpha-tocopherol was similar. LDL isolated with KBr solutions appeared to bind 20-45% more of the probucol present in serum than LDL isolated in isotonic solutions prepared with D2O. This was the case with probucol incorporated into plasma or serum in vivo or in vitro. Five out of seven LDL isolated with the D2O procedure from different human sera appeared more resistant to Cu(2+)-catalyzed oxidation than those obtained with KBr gradients from the same serum. In addition to the gradient procedure, we also describe a preparative version of the method that can be used with multiple samples.

Reoxygenation-induced cell damage of isolated neonatal rat ventricular myocytes can be reduced by chain-breaking antioxidants

To study the role of chain-breaking antioxidants on reperfusion injury in the ischemic heart, cultured ventricular heart cells (myocytes) were subjected to hypoxia and reoxygenation. The myocytes were prepared from neonatal rats and cultured in F10 medium that was supplemented with serum. As a marker for cell damage, lactate dehydrogenase was analyzed in the medium. Cells subjected to hypoxia for 5 h showed a 1.9 fold increase in lactate dehydrogenase (LD) leakage, while cells subjected to 1 h hypoxia followed by 4 h reoxygenation showed a 5-fold increase in LD intake. Alpha-tocopherol, beta-carotene, nordihydroguairetic acid (NDGA), butylated hydroxyltoluene (BHT), and ICI211965 were added to the cell medium every 24 h for 6 d prior to reoxygenation. All compounds protected against reoxygenation-induced cell damage. In the presence of the 5-lipoxygenase inhibitor ICI211965, protection against LD leakage was found only at high concentrations, which corresponded to the antioxidative effect of ICI211965, and not to inhibition of 5-lipoxygenase. We conclude that cultured ventricular myocytes can be used to evaluate the protective effect of antioxidants on reoxygenation-induced cell damage, and that chain-breaking antioxidants protected well against reoxygenation-induced cell damage.

Methods in laboratory investigation. Exclusion of trypan blue from microcarriers by endothelial cells: an in vitro barrier function test

The introduction of microcarriers in cell culture work has offered new possibilities not least in the study of endothelial biology. This article describes the use of microcarriers for selection of endothelial cells from mixed cultures by using a simple migration-transfer technique. Colonies of either endothelial or smooth muscle cells were allowed to form on gelatin-coated dishes with mitomycin-treated feeder cells. Microcarriers were then seeded so that one or two of them attached to each colony. The cells populated the microspheres within 2 to 3 days. Microcarriers from pure endothelial cell colonies were selected for transfer and serial subcultivation. Furthermore, a method to study the barrier function of confluent microcarrier cultures of endothelium was outlined. This method utilizes the fact that intact confluent cells exclude the dye trypan blue from the matrix of the microspheres which otherwise binds the dye tightly. The rate of absorption of trypan blue from a standard buffer containing 0.2% dye and 1 mg/ml of serum albumin by a standard volume of packed cell covered microspheres was determined. It was shown that confluent endothelial cells provided a barrier for the dye for several hours and that the subcellular matrix contributed to the barrier but only to a small extent. Treatment of the cells with dicloxacilline, 0.1 gm/ml, and homocysteine, at 8 mM, also influenced the barrier markedly. Dicloxacilline caused a complete breakdown and homocysteine clearly increased the rate of absorption of the trypan blue. It is suggested that the barrier function of cultured cells may be studied by this technique or future modifications based on similar principles.