Are cuffless devices challenged enough? Design of a validation protocol for ambulatory blood pressure monitors at the wrist: the case of the Aktiia Bracelet.

The US and European guidelines for the diagnosis and management of hypertension recommend the introduction of systematic home and night Blood Pressure (BP) monitoring. Fully-automated wearable devices can address the needs of patients and clinicians by improving comfort while achieving measurement accuracy. Often located at the wrist and based on indirect BP measurements, these devices must address the challenges of ambulatory scenarios. New validation strategies are needed, but little guidance has been published so far.In this work, we propose an experimental protocol for the validation of cuffless wrist BP monitors that addresses ambulatory environment challenges in a controlled experimental setting. The protocol assesses the robustness of the measurement for different body postures, the ability of the device to track BP changes, and its ability to deal with hydrostatic pressure changes induced by different arm heights.Performance testing using Aktiia Bracelet is provided as an illustration. The results of this pilot study indicate that the Aktiia Bracelet can generate accurate BP estimates for sitting and lying positions and is not affected by hydrostatic pressure perturbations.Clinical Relevance- Automated cuffless BP monitoring is opening a new chapter in the way patients are being diagnosed and managed. This paper provides a guidance on how to assess the clinical utility of such devices when used in different body positions.

Tuberculous lymphadenitis as a cause of obstructive jaundice.

Obstructive jaundice secondary to abdominal tuberculosis is extremely rare. We present a patient with jaundice secondary to compression of the common bile duct by TB lymphadenitis. A 49-year-old woman was admitted to our department for nausea,epigastric pain and jaundice. Abdominal ultrasonography and computer tomography scan were suggestive of stenosis of the distal common bile duct caused by a retro pancreatic mass. At laparotomy, an enlarged lymph node behind the head of the pancreas was found, causing compression and stenosis of the distal parts of the choledochus. The lymph node frozen section analysis showed epithelioid granuloma with caseous necrosis,strongly suggesting tuberculous origin. Choledochoduodenal anastomosis was performed. Definitive pathohistological examination confirmed TB lymphadenitis. ATB should be considered as a potential cause of jaundice especially in immuno compromised patients and endemic areas. Diagnosing abdominal tuberculosis can be a challenging task. No satisfactory diagnostic gold standard is available so that in most cases the diagnosis cannot be reached before exploratory laparotomy.Early detection enables successful conservative treatment and eliminates the necessity of surgery.

Poly(D,L-lactide-co-glycolide)/hydroxyapatite core-shell nanospheres. Part 4: a change of the surface properties during degradation process and the corresponding in vitro cellular response.

The surface properties of PLGA/HAp core-shell nanoparticles loaded with clindamycin obtained by an ultrasonic processing method and their changes under the simulated physiological conditions during the degradation process (when the morphology is changed starting from the nanospheres, over micrometer-sized plate-like films to a porous network) were investigated. The dynamic change of the surface properties of this material obtained in a water environment showed an increase of the surface area (up to 70 m(2)/g) and an improved wettability (estimated water contact angle was in the range between 40° and 60°) suggesting the possibility for its good interaction with cells. The in vitro tests are in a good correlation with this hypothesis, showing a high level of cytocompatibility of the material with the mouse L929 and human lung MRC-5 fibroblasts. The fibroblasts were able to achieve the contact with the material's surface and to attach onto it. The significance of HAp, as the bioceramic phase within the PLGA/HAp core-shell nanoparticles, may be brought into relationship with its role in improving the surface properties of PLGA/HAp obtained during the degradation process. These properties are closely related to the bioactivity and biocompatibility of this material, which are highly relevant for its biomedical application.

Controlled assembly of poly(D,L-lactide-co-glycolide)/hydroxyapatite core-shell nanospheres under ultrasonic irradiation.

An ultrasound field was applied to obtain PLGA/HAp biocomposite nanospheres. Formulation of PLGA/HAp composite revealed significant dependence of the morphology of the obtained composite on synthesis parameters, like the intensity of applied ultrasonic field, polymeric and ceramic parts' wt.% ratio in the composite, temperature of the medium, type of surfactant, and the sequence of steps in the formation of PLGA/HAp. Optimal parameters for the formation of PLGA/HAp included a lower content of the ceramic phase (PLGA/HAp=90:10), higher power of ultrasonic field (P=142.4W), lower temperature of the medium during ultrasonic treatment (T=8 degrees C), dilute solution of PVP as surfactant and dispersion of hydroxyapatite in polymer solution in order to achieve required homogeneity before the formulation of the composite. The morphology of PLGA/HAp particles synthesized under these conditions was highly regular: sphere-like, with particles of very small dimensions (150-320nm), highly uniform particle size distribution and characteristic planar spatial self-organization. These characteristics indicate significant improvements in PLGA/HAp composite resulting from ultrasonic method.

[Lead point as a poor prognostic factor in the therapy of invagination in children].

UNLABELLED: Invagination is specific form of bowel opstruction that is seen in 1-4 children per 1000 births, usually in the period from 3 to 12 months of age. In 90-95 % reason for invagination in unknown so we called this forms idiopathic. In 5-10% invagination is caused by specific leading point. THE AIM of this retrospective study was to determinate prognostic valye of used biochemical tests (hemograms, glucosa, electrolites ( levels of Na+, K+, Ca+ and Cl-) and to prove bad influence of existing "leading point" in therapy of invagination (weather it will be surgical or hydrostatic desinvagination). METHODS: We analised 65 patients with invagination. We devided all our patients into 2 groups: first group consisted patients with idiopathic forms of invagination, and the other one were patients with invagination coused by specific leading point. RESULTS proved that leading point in invagination has great implications on clinical presentation, laboratory results, diagnostic and therapeutic procedure, and finaly in prognosis.

Micro- and nano-injectable composite biomaterials containing calcium phosphate coated with poly(DL-lactide-co-glycolide).

Calcium phosphate/poly(dl-lactide-co-glycolide) (CP/DLPLG) composite biomaterial, in which each CP particle was coated with DLPLG, was synthesized. Two kinds of composites were prepared: microcomposite, with particles 150-200mum in size, and nanocomposite, with the particles 40+/-5nm in size. Using nanoparticles, a new class of injectible composite biomaterials was produced. Based on scanning electron microscopy, atomic force microscopy, differential thermal analysis, thermogravimetric analysis, differential scanning calorimetry and Fourier transform infrared analyses, the structure and phase organization in both biomaterials was identified and in both studied cases CP particles were coated with DLPLG polymer. An injectable composite biomaterial, the characteristics of which depend on the ratio of the phases, was prepared by mixing physiological solution with the nano-CP/DLPLG composite. Rheological studies indicated a possible agglomeration of particles of the injectable nano-CP/DLPLG composite biomaterial with a CP content of 65%.

Stereological analysis of the poly-(DL-lactide-co-glycolide) submicron sphere prepared by solvent/non-solvent chemical methods and centrifugal processing.

Fine particles made of poly(lactide-co-glycolide) (DLPLG) are excellent candidates for controlled release of delivering drugs and genes, because of their degradable nature. The preparation of DLPLG submicron spheres poses serious challenges that are not necessarily present when preparing macroparticles. In the present paper, DLPLG powder is produced with chemical method using solvent/non-solvent systems with subsequent centrifugation of the solution. The samples were characterized by infrared spectroscopy (IR), scanning electron microscopy (SEM) and stereological analysis. By changing the aging time with non-solvent and time and velocity of the centrifugal processing, it is possible to influence on the morphology and uniformity of the copolymer particles. Powder of the series with short aging time with non-solvent and longest time and velocity of the centrifugal processing has smallest particles and highest uniformity, where mean particles sizes were between 150 nm and 230 nm depending on which stereological parameters are considered (D(max), maximal diameters, feret X or feret Y).

Repair of bone tissue affected by osteoporosis with hydroxyapatite-poly-L-lactide (HAp-PLLA) with and without blood plasma.

The aim of this study is to examine the reparatory ability of the synthetic biomaterial hydroxyapatite-poly-L-lactide (HAp-PLLA), the replacement of alveolar ridge, and rehabilitation of bone defects caused by osteoporosis, in an experimental group of animals. The experiments are performed on syngeneic Sprague Dawley rats. Osteoporosis is induced by glucocorticoids in rats during a 12-week period. After this, the experimental group of animals is divided into five subgroups. An artificial defect is made in the alveolar bone on the left side of the mandible. In one group of animals, the defect is left to heal by itself, while in other groups, pure HAp-PLLA or one mixed with plasma is implanted. The best results are achieved by the implantation of the HAp-PLLA composite biomaterial mixed with autologous plasma. Formation of a new mandibular bone is seen, growing intensely, leading to rapid osteogenesis.

New biocomposite [biphasic calcium phosphate/ poly-DL-lactide-co-glycolide/biostimulative agent] filler for reconstruction of bone tissue changed by osteoporosis.

Biphasic calcium phosphate-poly-DL-lactide-co-glycolide composite biomaterial with and without biostimulative agents (protein-rich plasma or fibrin) was synthesised in the form suitable for reconstruction of bone defects. The composite used as filler was obtained by precipitation in solvent-non-solvent systems. The material, calcium phosphate granules covered by polymer, was characterised by wide-angle X-ray structural analysis, scanning electron microscopy, infrared spectroscopy and differential scanning calorimetry. Reparation of bone tissue damaged by osteoporosis was investigated in vivo on rats. The method applied enabled production of granules of calcium phosphate-poly-DL-lactide-co- glycolide composite biomaterial of average diameter 150-200 mum. Histological analysis confirmed recuperation of the alveolar bone, which osteoporosis-induced defects were repaired using composite biomaterial. By addition of biostimulative agents, intensity of osteogenesis increases accompanied by the formation of regular, new bone structure.

Biological evaluation of hydroxyapatite/poly-L-lactide (HAp/PLLA) composite biomaterials with poly-L-lactide of different molecular weights intraperitoneally implanted into mice.

Histopathologic analysis of the tissue with HAp/PLLA implants was made and the leukocyte formula and chemiluminescence response of peritoneal phagocytes 2, 7 and 12 weeks after intraperitoneal implantation studied. Implants were made of HAp/PLLA biocomposites with PLLA molecular weights of 50000 (HAp/PLLA(50)) and 430000 g/mol (HAp/PLLA(430)) and of crushed devitalized femur bone of a young Wistar rat. Leukocyte formula and chemiluminescence of peritoneal phagocytes showed no systemic inflammatory response. The studied implants caused locally weak inflammatory reaction. The resorption of implants ranges in intensity (polymer resorption, i.e. disappearance rate), from the highest with the bone implants, low with HAp/PLLA(50), to the lowest with the HAp/PLLA(430) implants. Good resorption of the biocomposites and its mutual ingrowth with connective tissue prove their good biocompatibility.

[D-dimer in the early detection of deep vein thrombosis in the lower extremity]. / D-dimer u ranom otkrivanju tromboze dubokih vena donjih ekstremiteta.

Deep vein thrombosis is important social and health care problem for its high incidence, pulmonary embolism-related mortality, and long-term sequelae which may be disabling (post-thrombotic syndrome and ulceration). The aim of our work was to determine the diagnostic potential and importance of D dimer in the early detection of deep vein thrombosis of lower extremities. Prospectively we have analyzed a group of 47 patients who were admitted to vascular department of Surgical Clinic in Nis during the period from 1.8.2001. to 31.3.2003. with echosonographically verified deep vein thrombosis of no more than 48 hours of duration. D dimer was measured before anticoagulant treatment started using commercial Nycomed test. The activation of coagulation process was detected with increase in D dimer values in 44 out of 47 examined patients (93.61%). D dimer is highly sensitive diagnostic tool that should be routinely used in the patients with suspected deep vein thrombosis of leg.

A study of HAp/PLLA composite as a substitute for bone powder, using FT-IR spectroscopy.

Chemically synthesized hydroxyapatite/poly-L-lactide (HAp/PLLA) composite biomaterial was studied in vivo. The biocomposite was implanted into Balb/c Singen mice and after 1 and 3 weeks removed from their organisms and analyzed by the FT-IR spectroscopy. After 1 week of testing in vivo the implanted sample gave a spectrum in which absorption bands arising from newly formed functional groups of amine and peptide can be seen. After 3 weeks, a spectrum with pronounced absorption bands at 3420 and 1650cm(-1) assigned to newly generated collagen, a component of the extracellular connective-tissue matrix, was registered. Also, decrease of the intensity absorption band at 1760cm(-1) originating from the C=O group of PLLA indicates bioresorption of the PLLA used. Analysis of the microstructure of the sample surface by scanning electron microscopy before and after implantation revealed bioresorption of the PLLA polymer phase and generation of collagen fibers at the sites of implanted bioresorptive PLLA. A mixture of autologous bone powder and HAp/PLLA biocomposite was also examined. After implantation, the same final products as in the case of HAp/PLLA composite biomaterial used alone were found.

Microstructural characteristics of calcium hydroxyapatite/poly-L-lactide based composites.

Besides its high osteoinductive properties, hydroxyapatite (HAp) exhibits a relatively low mechanical strength. In order to improve the mechanical properties and reliability of HAp based composites, the addition of selected polymers is highly recommended. The main objective of this work is to study the microstructural characteristics of HAp/poly-L-lactide (PLLA) composites obtained by cold or hot processing. The composites were prepared from a mixture of a chloroform solution of poly-L-lactide with granulated HAp. After elimination of chloroform by vacuum evaporation, dense compacts were obtained by cold or hot pressing. The pressing pressure ranged from 98.10 to 294.3 MPa for both cold and hot pressing. The hot pressing was performed in the temperature region 293-457 K for a time period of 15-60 min. Depending on the PLLA amount and the pressing procedure it is possible to obtain highly porous or nearly fully dense composites. The scanning electron microscopy examination of fracture as well as of free surfaces revealed that the final porosity and wetting are affected to a great extent by the synthesis conditions and amount of polymer added. An increase in temperature to 457 K for a longer period of time results in fully dense compacts. The formation of a nearly continuous polymer network that leads to the hardening of HAp has also been observed. However, it should be pointed out that some layers of HAp may be free of polymer film since PLLA penetrates more deeply into the porous HAp.

Synthesis and properties of hydroxyapatite/poly-L-lactide composite biomaterials.

Calcium hydroxyapatite (HAp) and poly-L-lactide (PLLA) were synthesized chemically. The obtained HAp was of high purity and, after special thermal treatment, of high crystallinity as well. Synthesis of PLLA was performed using L-lactide as a monomer and nontoxic initiator. In this way a polymer of large molar weight (about 400,000) was obtained. The HAp and PLLA obtained were used as constituents of the HAp/PLLA composite biomaterial, a potential material for implants. The composite was obtained by mixing completely dissolved PLLA with granules of HAp. The composite was compacted by cold and hot pressing at pressures of 49.0-490.5 MPa and temperatures of 20-184 degrees C. The material obtained at optimum process parameters had a density of 99.6% and compressive strength of 93.2 MPa.