Surface characterization and in vivo evaluation of laser sintered and machined implants followed by resorbable-blasting media process: A study in sheep

Background

This study aimed to compare the histomorphometric and histological bone response to laser-sintered implants followed by resorbable-blasting media (RBM) process relative to standard machined/RBM surface treated implants.

Material and Methods

Six male sheep (n=6) received 2 Ti-6Al-4V implants (1 per surface) in each side of the mandible for 6 weeks in vivo. The histomorphometric parameters bone-implant contact (BIC) and bone area fraction occupancy (BAFO) were evaluated.

Results

Optical interferometry revealed higher Sa and Sq values for the laser-sintered/RBM surface in relation to standard/RBM implants. No significant differences in BIC were observed between the two groups (p>0.2), but significantly higher BAFO was observed for standard/RBM implants (p<0.01).

Conclusions

The present study demonstrated that both surfaces were biocompatible and osseoconductive, and the combination of laser sintering and RBM has no advantage over the standard machined implants with subsequent RBM. Key words:Dental implants, osseointegration, resorbable- blasting media, sheep, in vivo.     

Challenges in the diagnosis and management of acromegaly: a focus on comorbidities

Introduction

Acromegaly is a rare, insidious disease resulting from the overproduction of growth hormone (GH) and insulin-like growth factor 1 (IGF-1), and is associated with a range of comorbidities. The extent of associated complications and mortality risk is related to length of exposure to the excess GH and IGF-1, thus early diagnosis and treatment is imperative. Unfortunately, acromegaly is often diagnosed late, when patients already have a wide range of comorbidities. The presence of comorbid conditions contributes significantly to patient morbidity/mortality and impaired quality of life.

Methods

We conducted a retrospective literature review for information relating to the diagnosis of acromegaly, and its associated comorbidities using PubMed. The main aim of this review is to highlight the issues of comorbidities in acromegaly, and to reinforce the importance of early diagnosis and treatment.

Findings and conclusions

Successful management of acromegaly goes beyond treating the disease itself, since many patients are diagnosed late in disease evolution, they present with a range of comorbid conditions, such as cardiovascular disease, diabetes, hypertension, and sleep apnea. It is important that patients are screened carefully at diagnosis (and thereafter), for common associated complications, and that biochemical control does not become the only treatment goal. Mortality and morbidities in acromegaly can be reduced successfully if patients are treated using a multimodal approach with comprehensive comorbidity management.

     

Modulation of spontaneous immunoglobulin production by natural killer cells in rheumatoid arthritis

Synovial fluid (SF) mononuclear cells obtained from patients with rheumatoid arthritis (RA) spontaneously produce large amounts of immunoglobulin. In the rheumatoid joint, natural killer (NK) cell activity is reduced in comparison with that in the peripheral blood (PB). We examined the ability of SF NK cells to modulate the spontaneous production of Ig in RA SF, and we contrasted this with the activity in PB from RA patients and from normal subjects. We found that the spontaneous production of IgG was greater in RA SF than in RA or normal PB. The baseline NK activity was significantly lower in RA SF than in RA or normal PB (P less than 0.005). Incubation with anti-Leu-11b and complement reduced NK activity in PB, but not in SF, and it significantly (P less than or equal to 0.021) increased IgG production in both RA SF and RA PB. Lysis of NK cells in this manner also resulted in a significant increase (P less than 0.02) in IgM production in RA SF. These results suggest that NK cells with a Leu-11b phenotype down-regulate the ongoing synthesis of IgG and IgM in the rheumatoid joint.     

Prostate cancer cell type-specific regulation of the human PTHrP gene via a negative VDRE

Parathyroid hormone-related protein (PTHrP) is expressed by prostate cancer cells. Since PTHrP increases the growth and enhances the osteolytic effects of prostate cancer cells, it is important to control the level of PTHrP expression in these cells. We show that 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) and its non-calcemic analogue, EB1089, suppress PTHrP mRNA and protein levels in the human prostate cancer cell lines PC-3 and LNCaP. The human PTHrP gene contains a sequence element homologous to the negative vitamin D response element within the parathyroid hormone gene. This DNA sequence (nVDRE(hPTHrP)) bound the vitamin D receptor (VDR) present in nuclear extracts from both PC-3 and LNCaP cells. However, when cloned upstream of the SV40 promoter and transiently transfected into PC-3 and LNCaP cells, nVDRE(hPTHrP) downregulated promoter activity in response to 1,25(OH)2D3 or EB1089 treatment in LNCaP, but not in PC-3, cells. These results may help to explain why some prostate cancers appear to be refractory to treatment with vitamin D analogues.     

Unequivocal identification of brown adipose tissue in a human infant

We report the unique depiction of brown adipose tissue (BAT) by magnetic resonance imaging (MRI) and computed tomography (CT) in a human 3-month-old infant. Based on cellular differences between BAT and more lipid-rich white adipose tissue (WAT), chemical-shift MRI and CT were both capable of generating distinct signal contrasts between the two tissues and against surrounding anatomy, utilizing fat-signal fraction metrics in the former and x-ray attenuation values in the latter. While numerous BAT imaging experiments have been performed previously in rodents, the identification of BAT in humans has only recently been described with fusion positron emission and computed tomography in adults. The imaging of BAT in children has not been widely reported and, furthermore, MRI of human BAT in general has not been demonstrated. In the present work, large bilateral supraclavicular BAT depots were clearly visualized with MRI and CT. Tissue identity was subsequently confirmed by histology. BAT has important implications in regulating energy metabolism and nonshivering thermogenesis and has the potential to combat the onset of weight gain and the development of obesity. Current findings suggest that BAT is present in significant amounts in children and that MRI and CT can differentiate BAT from WAT based on intrinsic tissue properties.     

Bone marrow plasma cell infiltration in light chain amyloidosis: impact on organ involvement and outcome

Abstract

Objectives: Prognosis of immunoglobulin light-chain (AL) amyloidosis depends mainly on the presence of cardiac involvement and the disease burden. A higher bone marrow plasma cell (BMPC) burden has been recognized as an adverse prognostic factor. The aim of our study was to analyze the correlation between the BMPC infiltration, clinical features and outcomes in patients with AL amyloidosis.

Methods: The clinical records of 79 patients with AL amyloidosis treated at a single institution.

Results: Median BMPC infiltration at diagnosis was 11% and significantly correlated with the serum free light-chain difference (p?<?.001). Patients with more than 10% BMPCs had more frequent cardiac involvement (86 vs. 63%; p?=?.015), a trend towards a higher early mortality (27 vs. 11%; p?=?.08) and a significantly shorter progression-free survival (PFS) (median of 18 vs. 48?months, p?=?.02) and overall survival (median of 33?months vs. not reached; p?=?.046). In the multivariate analysis, a BMPC infiltration over 10% retained its adverse prognostic value for PFS (HR?=?2.26; 95% CI, 1.048–4.866; p?=?.038). The use of new drugs seemed to overcome the negative prognostic impact of a higher BMPC infiltration.

Conclusion: Higher BMPC infiltration in AL amyloidosis might be associated with increased systemic organ damage, particularly cardiac involvement and is rarely related to the development of myeloma features.     

Effect of growth hormone on bacterial translocation in experimental short-bowel syndrome

Despite the adaptive process triggered in the remaining intestine by massive bowel resection, bacterial translocation (BT) is frequent under these conditions. Several trophic factors, including growth hormone (GH), are involved in the process of adaptation in short-bowel syndrome (SBS). However, the effect of GH on BT has not been investigated experimentally. The aim of this study was to test the hypothesis that GH administration prevents BT in rats with SBS receiving only parental nutrition (PN). Nineteen adult Wistar rats underwent central venous cannulation and were randomly assigned to one of two groups receiving for 10 days two treatment regimes: PN group (n = 10): fasting, all-in-one PN solution (300 ml · kg · 24 h, 280 kcal/kg · 24 h), 80% gut section including ileocecal valve; GH group (n = 9): fasting, same PN regime and resection plus GH 1 mg/kg s.c). At the end of the experiment, the rats were killed and mesenteric lymph nodes (MLN) and samples of systemic and portal blood were obtained and cultured. Several samples of full-thickness jejunal wall were taken for determining cell proliferation index (PCNA) and mucosal thickness. Jejunal mucosal thickness increased by 30% and PCNA index by 35% in GH-treated rats in comparison with those treated with PN alone. However, contrary to our expectations, BT expressed by positive culture of intestinal flora in portal blood, MLN, or systemic blood was found in 60% of PN and 87% of GH animals (P = 0.1). Translocation to the general circulation expressed by the presence of organisms in systemic blood was detected in 0% of PN and 44% of GH rats (P < 0.05). Although exogenous GH improves gut mucosal structure in rats with SBS treated with PN, it seems to increase rather than decrease mucosal permeability to intestinal bacteria.