Comportement rhéologique de biomatériaux pour l'ingénierie ostéoarticulaire et dentaire : matrices extracellulaires synthétiques et suspensions phosphocalciques

International audienceLes biomatériaux injectables constituent un domaine particulier d'utilisation par voie percutanée des biomatériaux. Cela leur impose certaines propriétés rhéologiques lors de leur mise en œuvre. Au cours de ces travaux, le principal objectif fut d'évaluer les propriétés rhéologiques de deux biomatériaux injectables utilisés en ingénierie ostéoarticulaire et dentaire : (i) une matrice extracellulaire synthétique et (ii) une suspension phosphocalcique injectable. Un hydrogel, hydroxypropylméthylcellulose silanisée (HPMC-Si) a été obtenu par greffage de 3-glycidoxypropyltriméthoxysilane (GPTMS) sur les groupements hydroxyle d'une hydroxypropylméthylcellulose commerciale. Les propriétés rhéologiques de la solution avant et lors de la gélification ont été étudiées. Les résultats ont montré que la silanisation réduit le volume hydrodynamique des solutions diluées, mais n'affecte pas de manière significative le comportement rhéologique des solutions concentrées. Nous avons observé que la stérilisation des solutions d'HPMC-Si réduit le volume hydrodynamique des chaînes macromoléculaires et que l'augmentation du pH des solutions concentrées stériles réduit leur viscosité limite. L'étude de la thermogélification de l'HPMC a montré une séparation de phase durant la stérilisation. Les associations intra- et intermoléculaires, non totalement réversibles, établies lors de cette étape peuvent être responsables des modifications des propriétés rhéologiques. La formation de différents hydrogels à partir des solutions basiques d'HPMC-Si a été étudiée. Grâce à la caractérisation rhéologique de ces hydrogels, nous avons montré que la cinétique de réticulation, ainsi que les propriétés viscoélastiques, dépendent de la concentration finale en HPMC-Si, du pH final et de la température. Une suspension de céramique phosphocalcique injectable considérée comme un substitut osseux injectable prêt à l'emploi a été étudiée. La caractérisation rhéologique de l'HPMC, qui constitue le fluide suspendant de cette suspension, a confirmé le comportement d'une solution macromoléculaire. La cinétique de sédimentation des particules phosphocalciques a montré l'influence de la taille des particules et la concentration du fluide suspendant sur la vitesse de sédimentation et sur la compacité des sédiments avant et après stérilisation. Les propriétés rhéologiques et d'injectabilité de cette suspension phosphocalcique ont ensuite été étudiées. Nous avons montré que les suspensions présentent une viscosité plus élevée par rapport à la solution d'HPMC et que les propriétés rhéologiques dépendent de la composition de la suspension. La simulation d'injection a été réalisée grâce à une seringue munie d'une aiguille. Une approche théorique basée sur l'écoulement capillaire d'un fluide non newtonien a été utilisée pour prédire la pression d'injection à partir des résultats rhéologiques et des conditions opératoires d'extrusion. L'estimation théorique de la pression d'extrusion a confirmé le glissement à la paroi. L'influence du glissement a conduit à un facteur de proportionnalité constant entre la théorie et l'expérience

Cellulose-Based Hydrogels: Patent Analysis

Background: Among biopolymers, cellulose and its derivatives are the most commonly used for hydrogel formulations. The innovation and improvement of cellulose-based hydrogels concerned the raw materials, synthesis and methods of preparation, formulations and fabrication processes, as well as applications. Objectives: This study, in the form of patent analysis, presents the state by introducing what has been innovated and patented concerning cellulose-based hydrogels. Methods: Three databases have been used in this study: the Patentscope, the Espacenet, and the Lens patent data set. A detailed analysis has been provided regarding publication dates, patent families, jurisdictions, inventors, applicants, owners, and patent classifications. Results: A total of 8053 patent documents related to cellulose-based hydrogels have been published between 1965 and 2021. The United States leads the patent race in this sector, and the Massachusetts Institute of Technology is one of the top academic applicants. Conclusion: Based on patent classifications, most patent documents are related to medicinal preparations characterized by special physical forms. More specifically, the classification concerns materials for prostheses or coating prostheses, including cellulose derivatives characterized by their function or physical properties, such as macromolecular gels, hydrogels, or hydrocolloids

Giant aortic root aneurysm associated with postductal coarctation of aorta

The aorta is a large blood vessel that carries blood from the heart to the rest of thebody. The aortic root consists of the aortic valve and the openings for thecoronary arteries (the coronary ostia). An aortic aneurysm is an abnormal bulgein the wall of the aorta. If an aneurysm develops in the aortic root, the aorta candilate and the aortic valve can leak. If the aneurysm continues to expand, it canrupture and can cause life-threatening internal bleeding.Aneurysms of the aortic root are often due to degenerative disease of media.Aneurysm of the aortic root often affects patients in their second to fourthdecades of life. These aneurysms can cause aortic insufficiency, dissection,and/or rupture.Small and slow-growing thoracic aortic aneurysms may not everrupture, but large, fast-growing aneurysms may rupture.Depending on the size and growth rate of aortic aneurysm, treatment may varyfrom watchful waiting to emergency surgery. Ideally, surgery for a thoracic aorticaneurysm can be planned if necessary. Current guidelines recommend surgicaltreatment when the diameter of the aneurysm exceeds 50 mm. Here we report acase of thoracic aneurysm with postductal coarctation of aort

Gelation studies of a cellulose-based biohydrogel: the influence of pH, temperature and sterilization.

International audienceThe present paper investigates the rheological properties of silated hydroxypropylmethylcellulose (Si-HPMC) biohydrogel used for biomaterials and tissue engineering applications. The general property of this modified cellulose ether is the occurrence of self-hardening due to silanol condensation subsequent to a decrease in pH (from 12.4 to nearly 7.4). The behavior of unsterilized and sterilized Si-HPMC solutions in diluted and concentrated domains is first described and compared. In addition, the influence of physiological parameters such as pH and temperature on the rate of the gelation process is studied. In dilute solution, the intrinsic viscosity ([eta]) of different pre-steam sterilization Si-HPMC solutions indicates that macromolecular chains occupy a larger hydrodynamic volume than the post-steam sterilization Si-HPMC solutions. Although the unsterilized Si-HPMC solutions demonstrate no detectable influence of pH upon the rheological behavior, a decrease in the limiting viscosities (eta(0)) of solutions with increasing pH is observed following steam sterilization. This effect can be explained by the formation of intra- and intermolecular associations during the sterilization stage originating from the temperature-induced phase separation. The formation of Si-HPMC hydrogels from injectable aqueous solution is studied after neutralization by different acid buffers leading to various final pHs. Gelation time (t(gel)) decreases when pH increases (t(gel) varies from 872 to 11s at pH 7.4 and 11.8, respectively). The same effect is observed by increasing the temperature from 20 to 45 degrees C. This is a consequence of the synergistic effect of the increased reaction rate and acid buffer diffusion. pH and temperature are important parameters in the gelation process and their influence is a key factor in controlling gelation time. By adapting the gel parameters one could propose hydrogels with cross-linking properties adapted to clinical applications by controlling the amount of pH of neutralization and temperature

Cough, Hemoptysis and Hair Expectoration: An Intrapulmonary Teratoma

Teratomas can be found in different organs of the body and may involve gonads, saccrococcygeal region, mediastinum and other sites. Intrathoracic teratomas always occur in mediastinum and less often arise within the lung. As teratomas mostly involve sex organs (gonads), they rarely occur as extra-gonadal tumors accounting for only 3% of all the cases and very small percentage of such tumors occur in mediastinum.We reported an interesting case of middle aged male who presented to us with symptoms of cough, hemoptysis and trichoptysis (hair expectoration).We found that patient had intrapulmonary teratoma that was initially being treated as case of pulmonary tuberculosis. He underwent surgical resection of his cavitatory lesion and diagnosis of intrapulmonary teratoma was confirmed by histopathology as well. The patient made remarkable recovery with complete disappearance of his symptoms. From Pakistan no such case has ever been reported. Although it is very unusual but in patient with cavitatory lesion, intrapulmonary teratoma should always be kept in mind as differential diagnosis

Imaging and intervention for coronary artery disease following irradiation of malignant thymoma

Thymomas are rare malignant epithelial growths, constituting 20% of mediastinal tumours. Resection followed by irradiation may be employed in all thymomas except for stage 1 thymomas. Mediastinal irradiation is associated with coronary artery disease. The mean duration of presentation of post-irradiation coronary artery disease is 16 years (range 3-29 years). In our patient coronary artery disease was found only a year post irradiation. A 55 year old male who presented with complaints of dyspnoea, retrosternal chest pain and heaviness since one year underwent resection for malignant thymoma followed by radiotherapy. He presented with coronary artery disease a year after undergoing mediastinal irradiation. On follow-up, patient was treated successfully by coronary artery bypass graft. This case is an unusual occurrence and suggests that mediastinal irradiation may result in significant coronary artery disease as early as within one year

Malignant ectopic thyroid tissue with distant metastasis: a case report

Introduction: Ectopic thyroid tissue is the most common form of thyroid dysgenesis. But primary malignant transformation in ectopic thyroid tissue is quite a rare entity, with follicular malignancy being the dominant form at ectopic sites. Very infrequently, malignant ectopic thyroid tissue can present with metastasis to lymph nodes. But we report a case of malignant ectopic thyroid tissue over manubrium sterni with distant metastasis. Case presentation: A 42-year-old Pakistani female presented with gradually increasing swelling on anterior aspect of manubrium sterni for last 6 months. She had no goitre and was clinically and biochemically euthyroid. Rest of systemic exam was also unremarkable. CT chest showed a circumscribed soft tissue density mass arising from sternum, measuring 3.9×3.9 cm, causing erosions of anterior, right lateral and posterior walls of sternum. Trucut biopsy of the sternal mass proved it to be thyroid tissue with follicular differentiation and occasional mitotic figures. Multiple nodules were also noted in thyroid gland in US neck. She underwent total thyroidectomy and excision of ectopic thyroid tissue over manubrium sterni. Extensive histopathological examination of primary thyroid gland showed benign nodular hyperplasia with no evidence of malignancy. Ectopic thyroid tissue showed minimally invasive follicular thyroid carcinoma with tumor size of 3.2×2.3 cm. Her postoperative 21-day biochemical profile showed TSH 22.345 μIU/ml (0.4–4.2), serum thyroglobulin 88.3 ng/ml, and anti-TG antibodies Conclusion: We describe the first case of its kind having malignant ectopic thyroid with metastasis to spine and ilium. Such cases may impose difficulties in their treatment decisions

Benign granulomatous polyp obstructing the bronchus.

Abstract Inflammatory endobronchial polyps are rarely encountered. We report a case of a 14 years old girl with a benign granulomatous polyp originating in the bronchus. Computed tomography scan showed an intraluminal soft tissue opacity while fiberoptic bronchoscopy revealed a large soft tissue mass completely occluding the left lower lobe. Rigid bronchoscopy under general anaesthesia identified a fleshy mass in the left main stem bronchus which was excised via bronchoscopy. The histopathology showed benign polyp with non-specific inflammation. The patient\u27s symptoms improved subsequently and no recurrence was reported till two years of follow-u

Incidental metastatic mediastinal atypical carcinoid in a patient with parathyroid adenoma: a case report.

Background: Atypical carcinoid arising from the mediastinal tissue is a rare neuroendocrine tumor and an association with parathyroid adenoma is very unusual. We report an unusual case of atypical carcinoid of mediastinum with metastasis in a patient presenting with parathyroid adenoma, which is the first case to be reported from Pakistan. Case presentation: A 51-year-old Pakistani man was seen in postoperative intensive care after right parathyroidectomy and mediastinal mass resection for the management of postoperative hypocalcaemia. He had a background history of dyspnea. Examination was unremarkable. Preoperative laboratory evaluation revealed a calcium level of 12.7 mg/dl, phosphate of 1.9 mg/dl, serum albumin of 4.8 g/dl, alkaline phosphate of 94 U/L, and serum intact parathyroid hormone level 413.8 pg/ml. A technetium-99m sestamibi parathyroid scan showed right parathyroid increased tracer uptake. Further workup revealed a large mediastinal mass which was diagnosed as atypical carcinoid after Tru-Cut biopsy. He underwent right-sided parathyroidectomy and resection of the mediastinal mass. The histopathology confirmed it to be a parathyroid adenoma and atypical carcinoid tumor of his mediastinum with metastasis in his lymph node and parathyroid gland. Somatostatin receptor scintigraphy revealed a well-defined focus in his left hypochondriac region consistent with a somatostatin receptor scintigraphy-avid tumor. He was started on everolimus and planned for octreotide therapy. Conclusions: We describe an incidental finding of atypical carcinoid of the mediastinum in a patient diagnosed as having parathyroid adenoma. Clinical manifestations of neuroendocrine syndromes are challenging. Some tumors cluster in a non-classic description with other common neoplasms. They rarely present in isolation, remain clinically silent, and need aggressive workup with the aid of imaging and histopathology