Polyanionic collagen membranes for guided tissue regeneration: Effect of progressive glutaraldehyde cross-linking on biocompatibility and degradation

The ultimate goal of periodontal therapy is to control periodontal tissue inflammation and to produce predictable regeneration of that part of the periodontium which has been lost as a result of periodontal disease. In guided tissue regeneration membranes function as mechanical barriers, excluding the epithelium and gingival corium from the root surface and allowing regeneration by periodontal ligament cells. This report aims to study the effect of glutaraldehyde (GA) cross-linking on mineralized polyanionic collagen (PAC) membranes by conducting a histological evaluation of the tissue response (biocompatibility) and by assessing the biodegradation of subcutaneous membrane implants in rats. We studied six different samples: a PAC, a PAC mineralized by alternate soaking processes for either 25 or 75 cycles (PAC 25 and PAC 75, respectively) and these films cross-linked by GA. Inflammatory infiltrate, cytokine dosage, fibrosis capsule thickness, metalloproteinase immunohistochemistry and membrane biodegradation after 1, 7, 15 and 30 days were measured. The inflammatory response was found to be more intense in membranes without cross-linking, while the fibrosis capsules became thicker in cross-linked membranes after 30 days. The membranes without cross-linking suffered intense biodegradation, while the membranes with cross-linking remained intact after 30 days. The cross-linking with GA reduced the inflammatory response and prevented degradation of the membranes over the entire course of the observation period. These membranes are thus an attractive option when the production of new bone depends on the prolonged presence of a mechanical barrier.

Apatite coating on anionic and native collagen films by an alternate soaking process

The present study focuses on apatite coating on collagen films, with various different densities of carboxyl groups, using an alternate soaking process. Anionic collagen (AC), which has different densities of carboxylic groups compared to native collagen (NC), was obtained by hydrolysis of carboxyamides of asparagine and glutamine residues. From X-ray diffraction analysis, apatite was found to be coated on AC and NC films. Peaks ascribed to apatite were observed at 26 degrees and 32 degrees in the diffraction patterns of hydroxyapatite crystals. The amount of apatite coated on both AC and NC collagen films continued to increase up to 100 reaction cycles. However, there is a significant difference in apatite coating between the two films. The amount of apatite formed on the surface of AC film increased 1.24 times faster than on NC film. The scanning electron photomicrograph images of the mineralized NC and the AC film coatings formed after 100cycles show that regular porous apatite coating had formed within the collagen fibrils. These results suggest that the higher content of carboxyl groups in AC plays an effective role in the heterogeneous nucleation of apatite in the body environment.

On the dielectric behaviour of collagen–algal sulfated polysaccharide blends: Effect of glutaraldehyde crosslinking

In this paper, impedance measurements in the frequency range from 10(-2) to 10(6) Hz are presented for collagen and algal sulfated polysaccharide crosslinked films. We are considering the development of new biomaterials which have potential applications in coating of cardiovascular prostheses, support for cellular growth and in systems for controlled drug delivery. The effect of crosslink sulfated polysaccharide on the physical chemical properties of collagen was studied using FT-infrared spectroscopy, differential scanning calorimetry (DSC), dielectric spectroscopy. The resulting films crosslinked with glutaraldehyde (GA) in concentrations of 0.001% and 0.05% when analysed by DSC, showed that the GA treatment not only left the thermal stability of the collagen unaffected, but it also decreased the thermal transition energy. Dielectric spectroscopy shows that the effect of the crosslink on the blend film was associated to the decrease and stabilization of the dielectric permittivity at low frequencies and decreased its conductivity.

The use of 99mTc-phytate for sentinel node mapping in melanoma, breast cancer and vulvar cancer: a study of 100 cases

Sentinel node mapping reduces surgical morbidity and allows the use of more accurate tumour staging techniques. Radionuclide studies are preferentially performed using small colloids, which have limited availability in our country. The possibility of using phytate for sentinel node mapping was raised because of the similarity between its biodistribution and that of nanocolloids in the reticulo-endothelial system. In this paper we evaluated the use of 99mTc-phytate for sentinel node mapping, correlating the histopathological results with the status of the rest of the lymph node chain in different malignant tumours. A total of 100 patients were studied. group 1 consisted of 62 patients with breast cancer, group 2 of 20 patients with melanoma and group 3 of 18 patients with vulvar carcinoma. Lymph node scintigraphy was carried out after injecting 99mTc-phytate subdermally, and the sentinel node projection was marked on the skin. After 18-24 h, intraoperative sentinel node localisation was performed using a gamma probe (combined with visual localisation using patent blue dye) in 75 patients, and lymph node dissection was then carried out. Radionuclide scintigraphy identified the sentinel node in 98% of all studies. Intraoperative detection using the gamma probe was equally efficient: group 1=93% (38/41), group 2=95% (18/19) and group 3=100% (15/15). The sentinel node was involved in 41%, 31% and 20% of cases in groups 1, 2 and 3, respectively. Among the patients with positive nodes, the sentinel node was the only one affected in 53% of group 1, 50% of group 2 and 67% of group 3 cases. The method's negative predictive value was 91% in group 1 and 100% in the other groups. One false-negative study occurred in a patient who had a multifocal tumour and an intraparenchymatous lymph node; another occurred in a patient with a macroscopically affected node found during surgery. There were no side-effects related to the 99mTc-phytate. It is concluded that scintigraphic and intraoperative sentinel node identification was satisfactorily performed using 99mTc-phytate. The results were comparable to those previously described in the literature using other radiopharmaceuticals. Easy availability and low cost justify the use of phytate in our practice.

Periareolar mammaplasty: double skin technique with application of polyglactine or mixed mesh

This paper presents the author's experience of 7 years in 254 patients operated on using a personal mammaplasty technique with a periareolar approach. The technique is based on the principle that the skin alone does not prevent early ptosis. This paper proposes the repositioning of all breast connective structures, treating the glandular set separately from the cutaneous lining, which is doubled, applying a circular flap of dermis with the central pedicle to the areolar region. For this purpose, the following structures have been employed, which, once repositioned and together, will act as a support network: (1) anterior pectoral fascia, (2) Cooper's intramammary ligament, (3) periareolar dermal flap, employed as skin inner lining. (4) application of absorbable polyglactine 910 or mixed mesh (with polyester) as a sandwich between both layers of skin, and (5) external cutaneous lining that composes the assembly of double skin.

Steroid receptors in breast angiosarcoma

The presence of receptors for estrogen, glucocorticoid and progesterone was determined in the cytosol of two breast angiosarcomas. Estrogen and glucocorticoid receptors were present in both of them. Progesterone receptors were present in one of the two tumors assayed. Occupied nuclear estrogen receptors have been found in the nuclear extracts of both tumors. Unoccupied nuclear receptors were found only in the progesterone-positive tumor. Density gradient analysis suggested that glucocorticoid and estrogen bindings were located predominantly in the 6S and 7 to 8S regions, whereas receptor for progesterone sedimented at 4S.

Steroid receptors in a group of Brazilian breast cancer patients

Two hundred and forty-two primary breast cancers were assayed for estrogen receptors (ER). Of these, 202 were analyzed for progesterone receptors (PR) and 155 for glucocorticoid receptors (GR). ER was positive in 58% of the specimens; PR and GR were positive in 57%. A positive association was found between ER but not PR or GR frequency and age. Frequency of ER, PR, and GR positivity was approximately the same in premenopausal and postmenopausal women but ER content was much higher in postmenopausal women. About 70% of ER+ patients were also PR+ and GR+. Both frequency of PR positivity as well as average concentration, and frequency of GR positivity as well as average concentration were positively correlated with ER.