The combined effects of binder addition and different sintering methods on the mechanical properties of bovine hydroxyapatite.

Hydroxyapatite (HA) from bovine bones has been used as a biomaterial in dentistry due to its biocompatibility and bioactivity. However, dense HA bioceramics still present inadequate properties for applications that require high mechanical performance, such as infrastructure. Microstructural reinforcements and control of ceramic processing steps are methods to improve these shortcomings. The present study assessed the effects of polyvinyl butyral (PVB) addition in combination with two sintering methodologies (2-step and conventional), on the mechanical properties of polycrystalline bovine HA bioceramics. The samples were divided into four groups (with 15 samples per group): conventional sintering with binder (HBC) and without binder (HWC) and 2-step sintering with (HB2) and without binder (HW2). HA was extracted from bovine bones, turned into nanoparticles in a ball mill, and subjected to uniaxial and isostatic pressing into discs, according to ISO 6872 standards. All groups were characterized by x-ray diffractometry (XRD), differential thermal analysis (DTA) and Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and relative density. Besides, mechanical analyses (biaxial flexural strength (BFS) and modulus of elasticity) were also performed. The characterization results demonstrated that adding agglutinants or the sintering method did not affect HA's chemical and structural characteristics. Even so, the HWC group showed the highest mechanical values for BFS and modulus of elasticity being 109.0 (98.0; 117.0) MPa and 105.17 ± 14.65 GPa, respectively. The HA ceramics submitted to conventional sintering and without the addition of binders achieved better mechanical properties than the other groups. The impacts of each variable were discussed and correlated to the final microstructures and mechanical properties.

Relaxed skin tension lines.

In order to obtain the least scarring following a surgical procedure, it is crucial that the surgeon always consider the direction of the relaxed skin tension lines involved in the procedure and attempt to obtain a scar that follows that direction as much as possible. No other factor (except the region where the surgery is to be performed) is as important in obtaining an acceptable scar, including the too frequently heralded factor, surgical technique. This article deals with the determination and surgical application of the relaxed skin tension lines.

Timing of scar revision techniques.

In attempting to prevent or to treat unsatisfactory linear scars by the utilization of one of three scar revision techniques, it is important that the surgeon realizes that there are factors beyond his control and factors under his control. This article reviews the current procedures available for scar revision.

Relaxed skin tension lines (RSTL) versus other skin lines.

The seven best known skin tension lines are presented. The directions they convey are schematically compared with those of the relaxed skin tension lines. Commentaries and discussion by the author are given in order to help the reader arrive at his or her own conclusions on which directions his or her incisions should take so as to obtain the best scarring.

Choosing the correct Limberg flap.

A technique is presented for designing the 8 possible Limberg flaps to close any given rhomboidal defect. Then we show how to choose out of those 8 the only two that will be correctly oriented so the donor area of the Limberg flap can be closed with a minimal amount of tension.

The rhombic flap.

The Limberg rhombic flap is one of the best techniques for covering a skin defect that is not amenable to straight-line closure. It is a simple, versatile technique that requires only the correct placement of a rhombic donor flap for its execution. An easy method is presented for planning the design of a rhombic flap to take full advantage of all its possibilities.

The enigma of Serre's "Z-plasty" technique.

In 1835, Serre performed an operation to correct a cicatricial displacement of the right mouth commissure, which he described in his 1842 book. The drawings shown in a plate in the book (Fig. 2) and the description of the technique in the legend depicted the technique he had planned to perform (excision of tissue within lines ABCDE) but was not the technique he actually did. The description of the technique in the text of the book (Fig. 4) is very poor and incomplete. Apparently, he raised a triangular flap, which contained the right commissure, and sutured it into the skin defect on the check that he had created. The Z-plasty technique attributed to him (Fig. 1) in many textbooks is not the technique he had planned nor the technique he performed. He did not describe a Z-plasty but only the transposition of a single flap.

Unsatisfactory forehead scar following face lift.

The W-plasty scar revision technique has been found to be effective in the repair of the difficult and cosmetically unsatisfactory hairline scar following the ill-advised face lift technique that excises forehead skin.

[Infection by cytomegalovirus in patients with acquired immunodeficiency syndrome (AIDS): clinical, virological, and histopathological correlations]. / Infecção pelo citomegalovírus em pacientes com síndrome da immunodeficiência adquirida (AIDS): relações clínico-virológicas e anatomopatológicas.

Between April 1986 and June 1987, 50 patients meeting the CDC criteria for AIDS were studied for serological and virological evidence of CMV infection. Attempts for virus isolation from peripheral blood, urine and saliva were performed in cell culture lines of human foreskin fibroblasts and CMV specific IgG and IgM were assayed by IFI and IgG by ELISA. A total of 121 blood, 119 urine and 96 saliva samples were collected. During the study period viremia was noted at least once in 12.5%, viruria in 23.2%, and excretion in saliva in 21.9%. When admitted in the study, 20% (10/50) of the patients had anti-CMV IgM antibodies and 100% (50/50) of them had IgG anti-CMV antibodies (IFI). Five of the 40 patients IgM negative at admission presented anti-CMV IgM antibodies during the study, suggesting CMV reactivation or reinfection. Active CMV infection based on virus isolation and/or IgM positivity was demonstrated in 60% of the patients. Histopathological studies were performed in 24 patients. CMV was found in 50% of the autopsies, mainly in the digestive system, lungs and adrenals. There was no correlation between clinical, virological (serology and isolation) and histopathological diagnosis.

[Multiple retroperitoneal neurofibroma. Report of a case]. / Neurofibroma múltiplo retroperitoneal. Relato de um caso.

Tumors of nervous origin in the retroperitoneum are rare without specific symptoms which diagnosis is usually very difficult. The authors report a case of an asymptomatic patient with two benign retroperitoneal neurofibromas, one of them calcified and located near the inferior pole of the left kidney; the other tumor was closely adhered to the pancreatic tail in the supramesocolic region. Both were resected with appropriated surgical margins. The histopathologic and immunohistochemical studies established the correct diagnosis of the lesions. The authors comment the diagnostic tests of these tumors, their possible malignant degeneration and their surgical treatment.

PP138. Human fetal malformations associated with the use of angiotensin II receptor antagonist.

INTRODUCTION: antagonists of angiotensin II receptor (AAR) are commonly used for the treatment of chronic hypertension in the general population. Some of these pharmacological agents are losartan, candesartan, valsartan and tasosartan. Despite the good response achieved with these drugs in the control of hypertension, all medications that act directly on the renin-angiotensin system should be contraindicated during pregnancy. These drugs have been associated with fetal and neonatal injury, including hypotension, neonatal skull hypoplasia, anuria, reversible or irreversible renal failure and death.Here we report a case of fetal malformations and death associated with the use of losartan. OBJECTIVES: describing the association of fetal malformations and the use of losartan during first and second trimester of pregnancy. METHODS: this is a case report involving a 37-year-old pregnant woman at 26 gestational weeks. This patient had history of chronic hypertension for more than five years that was being regularly treated with Losartan 50mg/day. After her first consultation losartan was promptly discontinued and substituted for methyldopa. However, scan evaluation demonstrated severe oligohydramnios associated with altered fetal biophysical profile and altered Doppler fluxometry (absent diastolic flow at umbilical arteries). Therefore, a cesarean-section was performed after corticoid administration for fetal lung maturation. At first moment some characteristic alterations as fetal limb contractures and craniofacial deformation were detected at the 1007g new-born. This baby went to death 36h after delivery due to severe lung hypoplasia. RESULTS: the autopsy examination revealed renal tubular dysgenesis associated with changes secondary to nephropathy, probably induced by drug (Fig. 1). Associated findings were underdevelopment of bones of the skull with large fontanelles, thymus atrophy and signs of perinatal hypoxia. CONCLUSION: the difficulty of attending basic health assistance was attributed to be associated with this case, as this patient did not have opportunity and sufficient information about the necessity of changing her medication during pregnancy. Apart from this situation, this case report brings good information about the association between antagonists of angiotensin II receptor and human fetal malformations.