Bone grafting materials in dentoalveolar reconstruction: A comprehensive review.

Bone deficits of the jaws are often attributed to accidents, surgical removal of benign lesions or malignant neoplasms, congenital abnormalities, periodontal inflammation, tooth abscess or extraction and finally jaw atrophy due to advanced age or general disease. These bone defects require rehabilitation for a variety of reasons, e.g. maintaining the normal anatomic outline, eliminating empty space, aesthetic restoration and placing dental implants. Today, several techniques have been developed to eliminate these bone deformities including bone grafting, guided bone regeneration, distraction osteogenesis, use of growth factors and stem cells. Bone grafts consist of materials of natural or synthetic origin, implanted into the bone defect site, documented to possess bone healing properties. Currently, a variety of bone restorative materials with different characteristics are available, possesing different properties. Despite years of effort the 'perfect' bone reconstruction material has not yet been developed, a further effort is required to make this objective feasible. The aim of this article is to provide a contemporary and comprehensive overview of the grafting materials that can be applied in dentoalveolar reconstruction, discussing their properties, advantages and disadvantages, enlightening the present and the future perspectives in the field of bone regeneration.

Iodine intake and chronic autoimmune thyroiditis: a comparative study between coastal and mainland regions in Greece.

INTRODUCTION: The purpose of this study was to evaluate the relationship between iodine intake and autoimmune thyroiditis in Chios, an island located in the North East Aegean Sea, in comparison to mainland regions in South Western Greece (SWG). MATERIALS AND METHODS: Urine iodine concentration (UIC), thyroid function (serum TSH, thyroid autoantibodies: anti-TPO and anti-Tg), and thyroid U/S were assessed in 200 subjects (150 females and 50 males) from Chios and 322 subjects (255 females and 67 males) from several mainland regions in SWG. All participants were recruited from outpatient clinics and were diagnosed as euthyroid. RESULTS: Median UIC in Chios was significantly higher compared to SWG (136.1 vs. 104.5 µg/L, p < 0.001), indicating that both regions are iodine sufficient according to World Health Organization (WHO) criteria. The prevalence of thyroid autoimmunity was 66.5% in Chios and 27% in SWG, significantly higher in females (46.7%) than in males (26.5%). Furthermore, individuals with increased levels of thyroid autoantibodies either anti-TPO or anti-Tg (TAbs) showed increased median UIC levels compared to those / subjects / patients with normal levels (126.7 vs. 108.95 µg/L, p < 0.001). Serum TSH mean values (mIU/L) were greater in females (mean = 2.1 ± 1.41) compared to males (mean = 1.82 ± 1.26) (p = 0.04) and decreased with age. CONCLUSIONS: In conclusion, in the present study, we clearly indicate that increased thyroid autoimmunity is positively associated with increased iodine intake, as well as with the female gender. Moreover, iodine intake and thyroid autoimmunity appear to be significantly higher in a coastal region (Chios) than in mainland Greece (SWG). Additional environmental factors, apart from iodine, should be investigated in future studies. Mean TSH values were increased in females and decreased with age. The latter is probably due to the presence of autonomous goiter in older Greek populations, as a result of long-term status of iodine deficiency in the past.

Relationship of Changes in Cystatin-C With Serum Creatinine and Estimated Glomerular Filtration Rate in Kidney Transplantation.

BACKGROUND: Serum creatinine (S-Cr) is the most commonly used marker for the assessment of renal function in kidney transplantation (KTx). Cystatin-C (Cys-C) has been proposed as an alternative marker of renal function for the estimated glomerular filtration rate (eGFR), which seems to be more accurate than S-Cr. The aim of this study was to investigate the relationship between changes in S-Cr, Cys-C, and eGFR measurements in KT patients during the early post-transplantation (post-Tx) period. METHODS: Fifty consecutive patients, aged 15 to 70 years, were subjected to KT. Blood samples were collected at stable time-points on pre-Tx and post-Tx days 2, 6, and 14 and in the third month. Cys-C and S-Cr levels were measured, and GFR was estimated at all time-points using the Cockcroft-Gault and Le Bricon equations. RESULTS: S-Cr and Cys-C levels decreased significantly post-Tx in all time-point determinations compared with pre-Tx levels. Both markers showed a parallel decrease, reaching normal levels in the third month. Estimated GFR post-Tx by S-Cr and Cys-C exhibited a parallel progressive increase without significant difference between the calculations. Correlation between S-Cr and Cys-C in all time-point determinations was positive and of high significance using Pearson's correlation (r = 0.969, P < .01; r = 0.951, P < .01; r = 0.969, P < .01; r = 0.701, P < .01). Also, the correlation between the eGFR by Cys-C and S-Cr was positive and of high significance in all post-Tx calculations (r = 0.896, P < .01; r = 0.935, P < .01; r = 0.929, P < .01; r = 0.861, P < .01). Ten recipients had acute rejection and were treated successfully with antirejection therapy. Their S-Cr, cys-C, and eGFR results were analyzed separately and showed a significant difference from no-rejection patients, with Cys-C being more sensitive to earlier eGFR changes. CONCLUSION: Cystatin-C is an alternative and accurate marker of renal function in KT patients showing similar diagnostic characteristics to S-Cr. However, Cys-C appears superior to S-Cr in reflecting early GFR temporary changes, which is critical for the early detection of acute rejection.

Islet preparation purity is overestimated, and less pure fractions have lower post-culture viability before clinical allotransplantation.

BACKGROUND: Replacement of ß-cells with the use of isolated islet allotransplantation (IT) is an emerging therapy for type 1 diabetics with hypoglycemia unawareness. The current standard protocol calls for a 36-72-hour culture period before IT. We examined 13 clinical islet preparations with ≥2 purity fractions to determine the effect of culture on viability. METHODS: After standard islet isolation and purification, pure islet fractions were placed at 37°C with 5% CO2 for 12-24 hours and subsequently moved to 22°C, whereas less pure fractions were cultured at 22°C for the entire duration. Culture density was targeted at a range of 100-200 islet equivalents (IEQ)/cm(2) adjusted for purity. Islets were assessed for purity (dithizone staining), quantity (pellet volume and DNA), and viability (oxygen consumption rate normalized to DNA content [OCR/DNA] and membrane integrity). RESULTS: Results indicated that purity was overestimated, especially in less pure fractions. This was evidenced by significantly larger observed pellet sizes than expected and tissue amount as quantified with the use of a dsDNA assay when available. Less pure fractions showed significantly lower OCR/DNA and membrane integrity compared with pure. The difference in viability between the 2 purity fractions may be due to a variety of reasons, including hypoxia, nutrient deficiency, toxic metabolite accumulation, and/or proteolytic enzymes released by acinar tissue impurities that are not neutralized by human serum albumin in the culture media. CONCLUSIONS: Current clinical islet culture protocols should be examined further, especially for less pure fractions, to ensure the maintenance of viability before transplantation. Even though relatively small, the difference in viability is important because the amount of dead or dying tissue introduced into recipients may be dramatically increased, especially with less pure preparations.

Human islet viability and function is maintained during high-density shipment in silicone rubber membrane vessels.

BACKGROUND: The shipment of human islets (IE) from processing centers to distant laboratories is beneficial for both research and clinical applications. The maintenance of islet viability and function in transit is critically important. Gas-permeable silicone rubber membrane (SRM) vessels reduce the risk of hypoxia-induced death or dysfunction during high-density islet culture or shipment. SRM vessels may offer additional advantages: they are cost-effective (fewer flasks, less labor needed), safer (lower contamination risk), and simpler (culture vessel can also be used for shipment). METHOD: IE were isolated from two manufacturing centers and shipped in 10-cm(2) surface area SRM vessels in temperature- and pressure-controlled containers to a distant center after at least 2 days of culture (n = 6). Three conditions were examined: low density (LD), high density (HD), and a microcentrifuge tube negative control (NC). LD was designed to mimic the standard culture density for IE preparations (200 IE/cm(2)), while HD was designed to have a 20-fold higher tissue density, which would enable the culture of an entire human isolation in 1-3 vessels. Upon receipt, islets were assessed for viability (measured by oxygen consumption rate normalized to DNA content [OCR/DNA)]), quantity (measured by DNA), and, when possible, potency and function (measured by dynamic glucose-stimulated insulin secretion measurements and transplants in immunodeficient B6 Rag(+/-) mice). Postshipment OCR/DNA was not reduced in HD vs LD and was substantially reduced in the NC condition. HD islets exhibited normal function postshipment. Based on the data, we conclude that entire islet isolations (up to 400,000 IE) may be shipped using a single, larger SRM vessel with no negative effect on viability and ex vivo and in vivo function.

Management of cystic and solid pancreatic incidentalomas: a review analysis.

Incidentally discovered pancreatic lesions that are asymptomatic have become much more common in recent years. It is important to characterize these lesions and to determine which patients can be safely observed and which should undergo an operation, as a substantial proportion of them might be malignant or premalignant. This review focus on the diagnostic approach and management of the different types of cystic and solid incidental pancreatic lesions based on appropriate clinical input, imaging screening and histological criteria. The task of developing guidelines to deal with an incidentally found pancreatic lesion, however, is much more complex and controversial than with other organs incidentalomas. In most series, pancreatic incidentalomas (PIs) <2 cm and of cystic appearance are likely to be benign, whereas those >2 cm are usually premalignant or malignant. Serous cystadenomas can reach very large size and are usually benign lesions. The presence of a solid mass or a mural nodule in a cystic lesion along with main pancreatic duct dilatation, thick septations and biliary obstruction are considered features suspicious of malignancy. Mucinous cystic neoplasms and intraductal papillary mucinous neoplasms are malignant or lesions of malignant potential and need surgical exploration. Solid lesions are much more likely to be premalignant or malignant and most of patients will undergo resection. The decision to operate rather than follow a solid lesion is a matter of tumor size and of clinical judgment based on the age and patient comorbidities. The present study should serve as a general guide and not applied as strict principles. Key words: cystic pancreatic incidentalomas, diagnostic approach, management, solid pancreatic incidentalomas.

Advanced donor age alone is not a risk factor for graft survival in kidney transplantation.

BACKGROUND: The use of kidneys from elderly deceased donors has substantially increased organ supply, although it is associated with worse graft function and survival rates. The risk of kidneys from elderly donors as well as expanded criteria donors (ECDs) on kidney transplant outcome was investigated. PATIENTS AND METHODS: Seventy-five kidney transplants from ECDs over a 5-year period were reviewed retrospectively. Old age and increased donor risk variables were analyzed separately in relation to graft function and survival. RESULTS: Sixty-four of 75 (85.3%) recipients had functioning grafts 5 years posttransplant. The overall actuarial graft survivals from 1 to 5 years were 87.5%, 68.1%, 57.3%, 55.4%, and 47.3%, respectively. Early graft function gave 47 (62.7%) kidneys remarkable actuarial survivals of 100.0%, 88.3%, 75.8%, 75.8%, and 68.4% at 1 to 5 years posttransplant, and 28 (37.3%) kidneys had delayed graft function with substantially decreased actuarial survival rates, ranging from 66.7% to 23.2%. Kidneys from elderly donors had considerable actuarial graft survival rates of 100.0%, 83.3%, 76.9%, 76.9%, and 67.0% from 1 to 5 years, respectively; these were the best graft survival rates compared with kidneys from the other donor categories. The other donor risk variables when associated with advanced age of any had an adverse effect on recipient graft function and survival, but no single risk variable alone, or a combination of any two, showed any statistically significant variability. CONCLUSION: Elderly kidney donors provided a substantial organ pool expansion without affecting patient and graft survival in many patients. ECDs can be utilized safely if adequate measures are taken.

Urological complications: analysis and management of 1525 consecutive renal transplantations.

Urological complications after renal transplantation increase morbidity, delay graft function, and occasionally lead to graft and/or patient loss. The aim of this study was to analyze the causes of and therapeutic approaches to urological complications in renal transplantation as they related to patient outcomes. A series of 1525 consecutive renal transplantations were performed over a 24-year period. Renal grafts were obtained in 814 cases from living-related and in 711 from cadaveric donors. A Lich-Gregoire ureterovesical reimplantation technique with minimal bladder wall dissection was employed in all cases. Ureteral stents were routinely used in cadaveric transplants and exceptionally among living-related grafts. Urological complications were classified according to the mechanism and site of urinary tract involvement: graft ureteropelvic junction obstruction/stenosis (A), ureteral obstruction/stenosis (B), ureterovesical anastomosis obstruction/stenosis (C), urinary leakage (D), and other (E). Overall, we encountered 96 urological complications (6.3%). Group C complications occurred in 29 cases (30.2%), followed by 27 cases (28.1%) for group B patients, 25 cases (26.0%) for group D, 12 cases (12.5%) for group A, and 3 cases (3.1%) for group E patients. Surgical intervention was required in 49 (51.0%) of all urological complications. The others (n = 47, 49.0%) were treated either conservatively or by minimally invasive procedures. A rapid diagnosis of urological complications, assisted by early posttransplant DTPA scans, routine ultrasonography, and especially prompt treatment, resulted in compensation of renal graft dysfunction in the vast majority (n = 90, 93.8%) of cases. Surgical techniques of graft retrieval and reimplantation are of utmost importance to minimize the incidence of urological complications.

Improving the organ transplantation program in Greece: institution of local transplant coordinators' network.

The success of a transplantation program depends upon the quality and effectiveness of the donation process, whereby the key role is assigned to the local transplant coordinator (TxC). This important professional figure was only recently established in Greece. The local TxC duties were outlined alongside those of the Hellenic Transplant Organization (HTO) foundation in 1999, whereby three different transplant coordinator positions--central, local, and clinical--were specified. In 2002, the above-mentioned positions were legally consolidated. Local TxCs had to be doctors or nurses, in a 70%-30% ratio, already working in intensive care unit (ICU) and had to be appointed by the hospital and ICU directors in each hospital as requested by the HTO. By the end of 2004, this network consisted of 122 TxCs located in 74 ICUs, especially trained in donation procedures and ethics. Half of the doctors were ICU directors, especially appointed to influence ICU personnel. Furthermore in 2005, the board of directors of HTO decided that there should be closer cooperation between the 45 most donor generating ICUs and their TxCs. It was decided that the local TxCs would work part-time and receive a monthly grant. The 45 ICU network started in 2005, resulting in an 154% increased rate of potential donor referrals and a 33% and almost 38% increase in actual donors and transplantations, respectively, compared to 2004. This substantial increase was achieved by the institution of TxC network.

Substantial increase in cadaveric organ transplantation in Greece for the period 2001-2005.

The Hellenic Transplant Organization (HTO), a nonprofit organization sector of the Greek Ministry of Health, was officially established in 1999. Since March 2001, HTO has been responsible for donation and transplantation processes in Greece and organ sharing between Greece and other European countries. The organization's main tasks are: donor referral, charting, donor assessment, organ evaluation, organ allocation and transplantation. Today, the results show increased success rates to previously believed unthinkable levels. Precisely, the percentage of referred versus used cadaveric donors increased by 468% and 134%, respectively. Cadaveric kidney transplantation has also shown remarkable progress with a 126% increase during the same period. Similarly, liver transplantation showed a threefold rise (89%) during the same time. Unfortunately, heart and lung transplantations remain low, thus preventing statistical conclusions to be drawn. Although Greece in previous years had the lowest donor and transplantation rates per million population, its position compared with other European countries is expected to rise significantly this year. Undoubtedly, the numbers and percentages compared to previous years are due to the radical changes implemented by the HTO, by introducing transplant coordination principles and procurement management, which were concepts not previously established in Greece. However, there are still major obstacles, such as intensivists' refusal to disconnect, inaccessible geographical locations, few transplant centers, and society's suspicion of organ donation concept, that still need attention. Nevertheless, the first step has been taken and other European countries standards will hopefully be attained soon.

Liver resection for metastatic non-colorectal non-neuroendocrine hepatic neoplasms.

AIMS: Major liver surgery can be performed safely and hepatic resection for metastatic disease is increasingly carried out. However, the role of liver resection for hepatic metastases from non-colorectal, non-neuroendocrine (NCNN) cancers is unknown. Our aim was to evaluate our experience from hepatectomies for NCNN metastases. A retrospective study of 170 patients with liver resection performed the last 8 years was performed in two liver units in affiliated university hospitals. METHODS: Eighteen patients underwent liver resection for NCNN tumours. Origins included kidney (n=6), breast (n=4), gastric tumours (n=4), intestinal leiomyosarcoma (n=2) and malignant melanoma and in one patient a metastatic papillary of unknown origin was found. Eleven patients underwent a hepatic lobectomy and seven had local resections. Ten hepatectomies were performed at the same time with the primary tumour resection (synchronous resections) with five of those in an en bloc fashion with the primary tumour. RESULTS: There were no post-operative deaths and the peri-operative morbidity was minimal. During a median follow-up time of 3.2 years, 14 patients are alive with one of them having developed pulmonary metastases. CONCLUSION: In carefully selected patients with NCNN liver metastasis, liver resection can prolong survival as well and improve quality of life.

Transplantation of islets of Langerhans in patients with insulin-requiring diabetes mellitus undergoing orthotopic liver transplantation--the Miami experience.

Most patients with cirrhosis of the liver have detectable insulin resistance. In 60-80% of patients with cirrhosis, impaired glucose tolerance can be uncovered; approximately 20% of these patients eventually develop overt diabetes. Theoretically, insulin resistance and glucose intolerance could be improved or reversed by orthotopic liver transplantation alone or in association with a simultaneous transplant of pancreatic islet cells from the same donor. To investigate these possibilities we initiated a pilot study of simultaneous liver and pancreatic islet cell transplantation in seven patients with diabetes and liver cirrhosis. Donor bone marrow cells were also infused to enhance the acceptance of the grafts. Seven patients who received only orthotopic liver transplantation and donor bone marrow cells were used as historical controls. The preliminary results of this pilot trial suggest that islet cell transplantation in conjunction with orthotopic liver transplantation improves glucose metabolism in patients with liver cirrhosis in association with reduced insulin requirements and HbA1c levels. These results were evident in spite of pre- and post-transplant basal C-peptide levels that were unchanged. Further evaluation of the effects of orthotopic liver transplantation with or without islet cell transplantation will require a randomized prospective trial including accurate metabolic evaluation with the euglycemic insulin clamp technique.