Defective lymphocyte glycosidases in the macrophage activation cascade of juvenile osteopetrosis

Generation of macrophage-activating factor requires a precursor protein, Gc protein (serum vitamin D3-binding protein), as well as participation of beta-galactosidase of inflammation-primed B lymphocytes and sialidase of T lymphocytes. The treatment of human peripheral blood mononuclear cells with an inflammatory lysophospholipid induced beta-galactosidase and sialidase activity of lymphocytes, leading to the generation of macrophage-activating factor and activation of monocytes/macrophages. However, lysophospholipid treatment of peripheral blood mononuclear cells from three infantile patients with osteopetrosis resulted in no significant activation of monocytes/macrophages. The lysophospholipid-inducible beta- galactosidase activity of B lymphocytes as well as that of the sialidase of T lymphocytes was found to be defective in these patients.     

Continuous template collection and updating for electrogram morphology discrimination in implantable cardioverter defibrillators

INTRODUCTION: Electrogram morphology analysis improves discrimination of supraventricular tachycardias (SVTs) from ventricular tachycardias (VTs) in implantable cardioverter defibrillators (ICDs), but electrogram morphology may change with lead maturation, drugs, or disease progression. We report the clinical performance of an automatic algorithm that creates and updates templates from non-paced, slow rhythm and continuously checks the quality of the template used for arrhythmia discrimination. METHODS AND RESULTS: We studied this algorithm in 193 patients with single-chamber ICDs (Marquis VR, Medtronic Inc., Minneapolis, MN, USA). Of the 112 patients who completed 6-month follow-up, 99.1% of the patients had > or =1 automatic template created. Match scores between template and ongoing rhythm are computed using Haar Wavelets. Of the 435 automatic templates evaluated at follow-up, 423 (97.2%) had a median match score > or =70%. Intrinsic rhythm at 1 month had significantly higher match scores (P < 0.001) with automatic templates (90.3 +/- 7.0%) than with manual templates (85.7 +/- 10.9%) generated at pre-hospital discharge (PHD). The percentage of appropriately rejected SVTs was slightly higher with the automatic template (280/339 episodes) than with the manual template at PHD (272/339 episodes) while the Wavelet detection of VT was the same (218/220 episodes). CONCLUSIONS: In patients receiving ICDs, the automatic templates were successfully created during a 6-month follow-up period, and consistently matched the patients' intrinsic rhythm at the nominal match threshold. Both early (<1 month postimplant) and late (1- to 3-month follow-up period) changes in electrogram morphology were identified, confirming the need for automatic template updating.     

Differentiation of low-molecular-weight heparins: impact on the future of the management of thrombosis

Low-molecular-weight heparins (LMWHs) are now universally accepted as drugs of choice for postsurgical prophylaxis and treatment of deep vein thrombosis (DVT). Currently, these agents are also being developed for the treatment of various cardiovascular conditions. Because of manufacturing differences, each of the LMWHs exhibits distinct pharmacologic and biochemical profiles. The specific activity of these agents in anticoagulant assays ranges from 35 to 45 anti-IIa U/mg, whereas the activity in terms of anti-Xa units is designated as 80 to 145 U/mg. These LMWHs are also capable of producing product-specific dose- and time-dependent antithrombotic effects in animal models of thrombosis. Although the ex vivo effects are initially present at dosages that are antithrombotic, these agents have been found to produce sustained antithrombotic effects without any detectable ex vivo anticoagulant actions. In experimental animal models and various clinical trials, these agents also have been found to release tissue factor pathway inhibitor and von Willebrand factor. In addition, LMWHs have been reported to produce fibrinolytic effects. The effect of repeated administration also exhibits product-based augmentation of the antithrombotic and hemorrhagic effects. Several new agents are being investigated as possible substitutes for heparins. These include anti-thrombin, anti-Xa, anti-TF (tissue factor), heparinoids, oral formulations of heparin, activated protein C, and biotechnologically derived serpins. These agents may not have the broad clinical spectrum as that observed with the heparins. More recently, several pharmaceutical companies have produced generic LMWHs.     

Discrete‐choice experiment to analyse preferences for centralizing specialist cancer surgery services

Background

Centralizing specialist cancer surgery services aims to reduce variations in quality of care and improve patient outcomes, but increases travel demands on patients and families. This study aimed to evaluate preferences of patients, health professionals and members of the public for the characteristics associated with centralization.

Methods

A discrete‐choice experiment was conducted, using paper and electronic surveys. Participants comprised: former and current patients (at any stage of treatment) with prostate, bladder, kidney or oesophagogastric cancer who previously participated in the National Cancer Patient Experience Survey; health professionals with experience of cancer care (11 types including surgeons, nurses and oncologists); and members of the public. Choice scenarios were based on the following attributes: travel time to hospital, risk of serious complications, risk of death, annual number of operations at the centre, access to a specialist multidisciplinary team (MDT) and specialist surgeon cover after surgery.

Results

Responses were obtained from 444 individuals (206 patients, 111 health professionals and 127 members of the public). The response rate was 52·8 per cent for the patient sample; it was unknown for the other groups as the survey was distributed via multiple overlapping methods. Preferences were particularly influenced by risk of complications, risk of death and access to a specialist MDT. Participants were willing to travel, on average, 75 min longer in order to reduce their risk of complications by 1 per cent, and over 5 h longer to reduce risk of death by 1 per cent. Findings were similar across groups.

Conclusion

Respondents' preferences in this selected sample were consistent with centralization.     

Impaired TRPV4-eNOS signaling in trabecular meshwork elevates intraocular pressure in glaucoma

Primary Open Angle Glaucoma (POAG) is the most common form of glaucoma that leads to irreversible vision loss. Dysfunction of trabecular meshwork (TM) tissue, a major regulator of aqueous humor (AH) outflow resistance, is associated with intraocular pressure (IOP) elevation in POAG. However, the underlying pathological mechanisms of TM dysfunction in POAG remain elusive. In this regard, transient receptor potential vanilloid 4 (TRPV4) cation channels are known to be important Ca²⁺ entry pathways in multiple cell types. Here, we provide direct evidence supporting Ca²⁺ entry through TRPV4 channels in human TM cells and show that TRPV4 channels in TM cells can be activated by increased fluid flow/shear stress. TM-specific TRPV4 channel knockout in mice elevated IOP, supporting a crucial role for TRPV4 channels in IOP regulation. Pharmacological activation of TRPV4 channels in mouse eyes also improved AH outflow facility and lowered IOP. Importantly, TRPV4 channels activated endothelial nitric oxide synthase (eNOS) in TM cells, and loss of eNOS abrogated TRPV4-induced lowering of IOP. Remarkably, TRPV4-eNOS signaling was significantly more pronounced in TM cells compared to Schlemm’s canal cells. Furthermore, glaucomatous human TM cells show impaired activity of TRPV4 channels and disrupted TRPV4-eNOS signaling. Flow/shear stress activation of TRPV4 channels and subsequent NO release were also impaired in glaucomatous primary human TM cells. Together, our studies demonstrate a central role for TRPV4-eNOS signaling in IOP regulation. Our results also provide evidence that impaired TRPV4 channel activity in TM cells contributes to TM dysfunction and elevated IOP in glaucoma.

Glaucoma is a heterogenic group of multifactorial neurodegenerative diseases characterized by progressive optic neuropathy. It is the leading cause of irreversible vision loss with more than 70 million people affected worldwide (1), and the prevalence is estimated to increase to 111.6 million by the year 2040 (2). Primary open angle glaucoma (POAG) is the most common form of glaucoma, accounting for ∼70% of all cases (1). POAG is characterized by progressive loss of retinal ganglion cell axons that leads to an irreversible loss of vision (1, 3). Elevated intraocular pressure (IOP) is a major, and the only treatable, risk factor associated with POAG (4). The trabecular meshwork (TM), a molecular sieve-like structure, maintains homeostatic control over IOP by constantly adjusting the resistance to aqueous humor (AH) outflow. In POAG, there is increased resistance to AH outflow, elevating IOP (5). This increase in AH outflow resistance is associated with dysfunction of the TM (6–8).The TM has an intrinsic ability to sense the AH flow and regulate outflow facility to maintain IOP homeostasis (6), although the precise flow-sensing mechanisms in TM cells are unclear. In this regard, transient receptor potential vanilloid 4 (TRPV4) cation channels have emerged as a major flow-activated Ca²⁺ entry pathway in multiple cell types (9–12). Upon activation, TRPV4 channels allow localized Ca²⁺ influx (termed as TRPV4 sparklets), which influences a variety of cellular homeostatic processes (13, 14). TRPV4 sparklets are spatially restricted signals with a spatial spread (maximum width at half maximal amplitude) of ∼11 microns (13). Treatment with a selective TRPV4 channel activator GSK1016790A (GSK101) lowered IOP in rats and mice (15). Furthermore, baseline IOP was higher in global TRPV4^−/− mice compared to their wild-type (WT) littermates (15). However, the exact cell type responsible for these IOP-lowering effects is not known. Previous studies have shown that TRPV4 channel protein is expressed in TM cells and tissues (15, 16). The physiological roles of TRPV4 channels in TM cells (TRPV4_TM) and downstream signaling mechanisms remain unknown. TM constitutively expresses Ca²⁺-sensitive endothelial nitric oxide synthase (eNOS) (17), a known regulator of outflow facility and IOP (18–22). In vascular endothelial cells, TRPV4 channels are important regulators of eNOS activity (23–26). We, therefore, hypothesized that TRPV4_TM-eNOS signaling promotes outflow facility and reduces IOP.Glaucoma-associated pathological changes are known to impair physiological function of TM (8). One of the hallmarks of the glaucomatous TM is its inability to maintain normal IOP and AH outflow resistance (6). Here, we postulated that impaired TRPV4_TM-eNOS signaling contributes to TM dysfunction and elevated IOP in glaucoma. In this report, our studies in human TM cells and TM tissue showed shear stress–mediated activation of TRPV4-eNOS signaling. Moreover, reduced AH outflow and elevated IOPs were observed in TM-specific TRPV4^−/− (TRPV4_TM^−/−) mice and eNOS^−/− mice. Importantly, TRPV4_TM activity and shear stress–mediated activation of TRPV4_TM-eNOS signaling are compromised in human glaucomatous TM cells. Our results provide direct evidence for a physiological role of TRPV4_TM-eNOS signaling and indicate that impaired TRPV4_TM-eNOS signaling may underlie TM dysfunction and IOP dysregulation in glaucoma.     

Melt extrusion: process to product

INTRODUCTION: Niche applicability and industrial adaptability have led hot melt extrusion (HME) techniques to gain wide acceptance and have, therefore, solidified their place in the array of pharmaceutical research and manufacturing operations. Melt extrusion's momentum has resulted in extensive research publications, reviews and patents on the subject for over a decade. Currently, > 50% of the new drug candidates are speculated to be highly lipophilic and thus poorly bioavailable. HME is a key technology for these and other formulation and processing issues. AREAS COVERED: Various approaches have been addressed using HME in developing solid molecular dispersions and have demonstrated viability to provide sustained, modified and targeted drug delivery resulting in improved bioavailability. This review provides a holistic perspective on HME from equipment, processing and materials to its varied applications in oral delivery (immediate release, sustained release, taste masking, enteric and targeted release, as well as trans-drug delivery), oral mucosal, dermal, ungual and intravaginal systems. EXPERT OPINION: Interest in HME as a pharmaceutical process continues to grow and the potential of automation and reduction of capital investment and labor costs has earned this technique a necessary consideration as a drug delivery solution.