Oxidative stress, anti-oxidants and the cross-sectional and longitudinal association with depressive symptoms: results from the CARDIA study

Depression may be accompanied by increased oxidative stress and decreased circulating anti-oxidants. This study examines the association between depressive symptoms, F2-isoprostanes and carotenoids in a US community sample. The study includes 3009 participants (mean age 40.3, 54.2% female) from CARDIA (Coronary Artery Risk Development in Young Adults). Cross-sectional analyses were performed on data from the year 15 examination (2000-2001) including subjects whose depressive symptoms were assessed with the Center for Epidemiologic Studies Depression Scale (CES-D) and had measurements of plasma F2-isoprostanes (gas chromatography/mass spectrometry) or serum carotenoids (high-performance liquid chromatography). Carotenoids zeaxanthin/lutein, β-cryptoxanthin, lycopene, α-carotene, β-carotene were standardized and summed. Longitudinal analyses were conducted using the data from other examinations at 5-year intervals. Cross-lagged analyses investigated whether CES-D predicted F2-isoprostanes or carotenoids at the following exam, and vice versa. Regression analyses were controlled for sociodemographics, health and lifestyle factors. F2-isoprostanes were higher in subjects with depressive symptoms (CES-D ⩾ 16) after adjustment for sociodemographics (55.7 vs 52.0 pg ml(-1); Cohen's d = 0.14, P < 0.001). There was no difference in F2-isoprostanes after further adjustment for health and lifestyle factors. Carotenoids were lower in those with CES-D scores ⩾ 16, even after adjustment for health and lifestyle factors (standardized sum 238.7 vs 244.0, Cohen's d = -0.16, P < 0.001). Longitudinal analyses confirmed that depression predicts subsequent F2-isoprostane and carotenoid levels. Neither F2-isoprostanes nor carotenoids predicted subsequent depression. In conclusion, depressive symptoms were cross-sectionally and longitudinally associated with increased F2-isoprostanes and decreased carotenoids. The association with F2-isoprostanes can largely be explained by lifestyle factors, but lower carotenoids were independently associated with depressive symptoms.

Diet quality and markers of endothelial function: the CARDIA study

BACKGROUND AND AIM

Dietary patterns are associated cross-sectionally with cellular adhesion molecules (CAMs). We studied prospective associations of three dietary patterns with CAMs.

METHODS AND RESULTS

In the Coronary Artery Risk Development in Young Adults (CARDIA) study, diet was assessed at years 0 (1985-86) and 7 (1992-93) examinations. Four circulating CAMs (E-selectin, P-selectin, soluble intercellular adhesion molecule 1 (sICAM-1), and vascular cellular adhesion molecule (VCAM)) were assayed at years 7 and 15 (2000-01). We created one index score "A Priori Diet Quality Score" and derived dietary patterns using principal components analysis (PCA). Multivariable linear regression models predicted year 15 CAMs from averaged (year 0/7) dietary patterns. The A Priori Diet Quality Score rated 46 food groups beneficial, neutral or adverse based on hypothesized health effects. We derived two PCA dietary patterns: "fruit and vegetables (FV)" (high intakes of fruit, vegetables, and whole grains) and "meat" (high intakes of red meat, refined grain, and butter). All dietary patterns were related to E-selectin and sICAM-1. P-selectin was not related to the FV dietary pattern. VCAM was only related to the A Priori Diet Quality Score. Strongest associations were for the meat dietary pattern with E-selectin (effect size 28% of an SD (+3.9/13.7 ng/mL)) and P-selectin (effect size 37% of an SD (+4.1/11.2 ng/mL)) and the A Priori Diet Quality Score with sICAM-1 (effect size 34% of an SD (-15.1/44.7 ng/mL)) and VCAM (effect size of 26% of an SD (-45.1/170.3 ng/mL)).

CONCLUSION

This prospective analysis suggests that dietary patterns are associated with CAMs.

Longitudinal association between serum urate and subclinical atherosclerosis: the Coronary Artery Risk Development in Young Adults (CARDIA) study

OBJECTIVE

The aim of the present study was to determine whether serum urate (sUA) concentration is positively associated with subclinical atherosclerosis, independent of body mass index (BMI), amongst generally healthy adults.

DESIGN AND SETTING

The CARDIA study followed 5115 Black and White individuals aged 18-30 years in 1985-1986 (year 0). Subclinical atherosclerosis comprised coronary artery calcified plaque (CAC; years 15, 20 and 25), and maximum common carotid intima-media thickness (IMT; year 20). sUA (years 0, 10, 15 and 20) was modelled as gender-specific quartiles that were pooled. Discrete-time hazard regressions and generalized linear regressions were used for analyses.

RESULTS

Mean sUA concentration was lower in women than in men and increased with age. Adjusting for demographic and lifestyle factors, the highest versus lowest quartile of sUA at year 0 was associated with a 44% [95% confidence interval (CI) 20%, 73%] greater risk of CAC progression from years 15 to 25 (Ptrend  < 0.001), which was attenuated by adjustment for BMI at year 0 (Ptrend  = 0.45). A stronger association was found between sUA at year 15 and CAC progression at year 20 or 25 (hazard ratio 2.07, 95% CI 1.66, 2.58 for the highest versus lowest sUA quartile Ptrend  < 0.001), which was attenuated, but remained significant with additional adjustment for BMI at year 15 (Ptrend  = 0.01). A greater increment in sUA concentration from year 0 to year 15, independent of change in BMI, was related to a higher risk of CAC progression (Ptrend  < 0.001). Similar associations were found between sUA and IMT, but only in men.

CONCLUSION

sUA may be an early biomarker for subclinical atherosclerosis in young adults; starting in early middle age, sUA predicts subclinical atherosclerosis independently of BMI.

Higher parity is associated with an increased risk of type-II diabetes in Chinese women: the Singapore Chinese Health Study

OBJECTIVE

The association between parity and type-II diabetes has been studied primarily in Western populations, and the findings have been inconsistent. Here, we examine whether parity was positively associated with incident type-II diabetes in Singaporean Chinese women.

DESIGN

Prospective cohort study.

SETTING

Singapore.

POPULATION

A total of 25,021 Singaporean Chinese women aged 45-74 years from the Singapore Chinese Health Study who were free of cancer, heart disease, stroke, and diabetes at baseline (1993-1998).

METHODS

Women were followed through 2004 for incident diabetes. Hazard ratios for type-II diabetes were computed across parity (of live births) categories and adjusted for baseline age, interview year, dialect, education, smoking, dietary pattern, physical activity, age at menarche, oral contraceptive use, menopausal status, hormone therapy use, and body mass index (BMI).

MAIN OUTCOME MEASURE

Self-reported diabetes, as diagnosed by a doctor.

RESULTS

Over an average of 5.7 person-years of follow-up, 1294 women were diagnosed with diabetes. Before and after multivariable adjustment there was a positive graded association between parity and type-II diabetes risk (P < 0.001). In the fully adjusted model, which included adult BMI, the risk of type-II diabetes increased by 31% (from -2 to 76%), 62% (from 22 to 116%), and 74% (from 29 to 133%) for women with one or two, three or four, and five or more live births, respectively, compared with women with no live births. Moreover, in a supplementary multivariate analysis in non-diabetic women we found a positive monotonic association between parity and glycated haemoglobin (HbA1c) (P = 0.01).

CONCLUSIONS

Increased parity may be a risk factor for type-II diabetes in Chinese women. More research is needed on lifestyle and physiologic factors that may explain this association.

Association between genetic variants in adhesion molecules and outcomes after hematopoietic cell transplants

Allogeneic hematopoietic cell transplant (HCT) is associated with a high morbidity and mortality. Adhesion molecules play an important role in endothelial activation and initiation of inflammatory response. We hypothesized that single nucleotide polymorphisms (SNPs) in the endothelial molecules may contribute to heterogeneity in HCT outcomes. We evaluated the association of 4 SNPs in ICAM1 (rs5498), PECAM1 (rs668 and rs1131012) and SELL (rs2229569) genes with acute and chronic graft-versus-host disease (GvHD) and those experiencing transplant-related mortality (TRM) within 1 year among 425 allogeneic HCT recipient-donor pairs. Using a Fine and Gray proportional hazards model to evaluate the association between genetic variants and clinical outcomes, after adjustment for recipient age, race, diagnosis, disease status, gender mismatch, cytomegalovirus serostatus, gender, donor type, conditioning regimen and year of transplant, only rs5498 in the ICAM1 gene among both recipients and donors was associated with a decreased risk of TRM (P ≤ 0.02). None of the SNPs were associated with acute or chronic GvHD risk. These findings suggest that genetic variants in the vascular adhesion molecules may be used to identify patients at high risk for TRM.

Contemporary nuclear medicine imaging of neuroendocrine tumours

Neuroendocrine tumours (NETs) are rare, heterogeneous, and often hormonally active neoplasms. Nuclear medicine (NM) imaging using single photon- and positron-emitting radiopharmaceuticals allows sensitive and highly specific molecular imaging of NETs, complementary to anatomy-based techniques, such as computed tomography (CT) and magnetic resonance imaging (MRI). Somatostatin-receptor scintigraphy is a whole-body imaging technique widely used for diagnosis, staging and restaging of NETs. The increasing availability of hybrid single-photon emission CT (SPECT)/CT cameras now offers superior accuracy for localization and functional characterization of NETs compared to traditional planar and SPECT imaging. The potential role of positron-emission tomography (PET) tracers in the functional imaging of NETs is also being increasingly recognized. In addition to 2-[(18)F]-fluoro-2-deoxy-d-glucose (FDG), newer positron-emitting radiopharmaceuticals such as (18)F-dihydroxyphenylalanine (DOPA) and (68)Ga-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) peptides, show promise for the future. This article will summarize the role of current and emerging radiopharmaceuticals in NM imaging of this rare but important group of tumours.

Molecular imaging in the management of thyroid cancer

Thyroid cancer is the most common endocrine malignancy in adults. The disease is classified into papillary, follicular, medullary and anaplastic types, each with characteristic histology and patterns of biological behavior. Diagnosis of thyroid cancer is usually made by needle aspiration of suspicious thyroid nodules. Disease management of well-differentiated thyroid cancer relies upon characteristic accumulation of radioisotopes of iodine that continues to play a central role in detection and treatment of disease. Recombinant human thyrotropin (rhTSH) is used as an alternative to thyroid hormone withdrawal to provide TSH stimulation necessary for diagnostic radioiodine scintigraphy and preparation for thyroid remnant ablation and cancer therapy. Hybrid SPECT/CT cameras combining functional scintigraphic information with CT anatomy are replacing stand-alone gamma cameras and these devices have been shown to outperform traditional planar and SPECT imaging techniques. Similarly, clinical application of novel radioisotopes like [124I]iodine with PET/CT for thyroid cancer imaging provides improved lesion resolution and direct tumor dosimetry. Alternative tracers such as [18F]fluorodeoxyglucose (FDG) can be used to evaluate well-differentiated thyroid cancers that no longer express the Na+/I- symporter, with a role in staging Hürthle cell, poorly differentiated, and anaplastic thyroid cancers. Medullary thyroid cancer recurrences are often difficult to detect using conventional imaging and traditional radionuclide studies, whereas [18F]FDG and [18F]fluorodihydroxyphenylalanine (DOPA) PET and PET/CT show promise for localizing the often elusive source (s) of elevated calcitonin in these patients.

Dual PET/CT with (18)F-DOPA and (18)F-FDG in metastatic medullary thyroid carcinoma and rapidly increasing calcitonin levels: Comparison with conventional imaging

BACKGROUND

To evaluate the role of a multi-imaging PET with (18)F-DOPA and (18)F-FDG in comparison with conventional imaging (CI) in recurrent medullary thyroid carcinoma (MTC).

METHODS

18 MTC patients who had thyroidectomy were included; they presented with elevated and rapidly increasing calcitonin levels during follow up. CI had revealed metastatic deposits in 9 patients. Patients were referred to us for a PET/CT with (18)F-DOPA and (18)F-FDG. Histologic/cytologic confirmation of recurrent MTC was obtained in at least one PET-positive lesion in all patients.

RESULTS

Foci of abnormal uptake were observed in 15 patients at (18)F-DOPA and in 11 at (18)F-FDG; 8 patients showed the same number of positive lesions with both tracers, 2 showed more lesions on (18)F-FDG, 1 was positive at (18)F-FDG alone and 5 at (18)F-DOPA alone. In 3 patients with a DOPA-positive loco-regional relapse a re-operation with curative intent was offered. SUV(max) values were higher for (18)F-FDG compared to (18)F-DOPA (mean 12.7+/-4.1 vs. 5.5+/-2.1, p<0.05). Calcitonin was higher in PET-positive patients compared to PET negative ones, while no significant differences were observed between (18)F-DOPA and (18)F-FDG positive patients.

CONCLUSIONS

In MTC patients with rapidly increasing calcitonin levels during follow up, (18)F-DOPA has a good sensitivity and a complementary role with (18)F-FDG PET/CT in detecting metastatic deposits. In our experience, the sensitivity of a multi-imaging (18)F-DOPA &(18)F-FDG PET/CT approach is greater than that obtained with CI. The higher SUV(max) values found with (18)F-FDG in some patients may reflect more aggressive tumors.

Scintigraphic localization of adrenal tumors

Scintigraphy has historically added much to the evaluation of adrenal dysfunction and tumor localization. The early development of radiopharmaceuticals for adrenocortical imaging provided vital clinical information well before the widespread availability of computed tomography (CT), but beginning in the early 1980's nuclear imaging became supplanted in large part by high resolution CT and more recently by magnetic resonance imaging. The parallel emergence of radiopharmaceuticals for adrenomedullary imaging also provided important functional insight in evaluating these neoplasms, but despite the clinical value of such nuclear probes they too, were relegated to a less prominent role in tumor characterization because of advances in anatomic imaging. However, with the recent introduction of dual-modality imaging platforms that directly combine CT with scintigraphy, either as single photon emission tomography (SPECT)/CT or positron emission tomography (PET)/CT, nuclear medicine studies once again play an integral role in adrenal tumor evaluation.

Pulmonary functional map on V/Q SPECT and TGFβ1 during radiotherapy and post-treatment lung function in patients with non-small cell lung cancer

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Background: Current research focus on the TGFß1 and pulmonary perfusion (Q) SPECT pre or post-treatment to predict lung toxicity in patients with non-small-cell lung cancer (NSCLC). However, ventilation (V) is also important, while the change of V/Q SPECT map and TGFβ1 during radiotherapy (RT) maybe more predictive for the lung function post-treatment. Methods: Patients with stage I-III NSCLC undergoing radiation based treatment were included and V/Q SPECT-CT, circulating TGF ß1 and carbon monoxide diffusing capacity (DLCO), as the key parameter of pulmonary function test, were assessed pre-, during- and 3 months post-RT. Patients were treated with conformal radiation therapy of more than 60 Gy, with or without chemotherapy per standard of care based on their stage of disease. The defects of V/Q SPECT images were defined by semi-quantitive method. Results: Total 45 patients with stage I-III NSCLC undergoing radiation (>60 Gy) were enrolled. All patients had functional defects (V, or Q or both) at or adjacent to the tumor and the V/Q defects were mismatched in 40%, 50% and 23% patients, pre-, during- and post-RT, respectively. After 45 Gy, the V and Q defects improved remarkably in 38.4% and 34.6% patients respectively, and the V scores were also improved significant during-RT (p<0.01). The Q scores of ipsilateral lung and V score of both lungs during-RT were correlated with DLCO 3 months post-RT margin-significantly (p=0.07) and significantly (p=0.02). The TGFß1 level decreased significantly during-RT and TGFß1 ratios (over the pre-RT level) at 4- and 6-week during-RT correlated with DLCO 3 months post-RT significantly (p=0.05). Conclusions: The V/Q SPECT map and TGFß1 level change during RT, and these changes are predictive for the lung function post-treatment in patients with NSCLC.

No significant financial relationships to disclose.

The role of PET in the surgical approach to adrenal disease

BACKGROUND

Appropriate surgical approach to diseases of the adrenal requires a diagnosis sufficient to determine the biochemical status of adrenal dysfunction and anatomic evaluation sufficient to differentiate unilateral from bilateral disease, intra-adrenal from extra-adrenal neoplasm, adrenal tumor recurrence or adrenal metastases. High resolution computed tomography (CT) and magnetic resonance have been the primary imaging modalities for the evaluation of anatomy, while scintigraphic studies have played a secondary role in diagnosis. The recent availability of functional imaging provided by positron emission tomography (PET) with radiopharmaceuticals designed to depict substrate precursor uptake, cellular metabolism or receptor binding in neoplasms and CT as a single modality, hybrid PET/CT, to directly correlate function and anatomy has had a significant impact upon the diagnostic and therapeutic approach to many cancers and has been applied to adrenal disease with some early success that we describe in this review.

METHODS

In addition to the authors' experience, a search of Medline and PubMed databases was performed using search terms: 'adrenal scintigraphy', 'positron tomography', 'computed tomography', 'adrenal surgery', 'adrenal mass', '(18)F-fluorodeoxyglucose', 'adrenal carcinoma', 'adrenal medulla' and 'pheochromocytoma'.

CONCLUSIONS

Present PET radiopharmaceuticals and their use in hybrid PET/CT have demonstrated efficacy in the preoperative and follow-up evaluation of neoplasms of the adrenal cortex and medulla that hopefully will continue to improve with the development of newer tracers that continue to exploit unusual characteristics of the adrenals.

Occlusion in implant dentistry. A review of the literature of prosthetic determinants and current concepts

Today the clinician is faced with widely varying concepts regarding the number, location, distribution and inclination of implants required to support the functional and parafunctional demands of occlusal loading. Primary clinical dilemmas of planning for maximal or minimal numbers of implants, their axial inclination, lengths and required volume and quality of supporting bone remain largely unanswered by adequate clinical outcome research. Planning and executing optimal occlusion schemes is an integral part of implant supported restorations. In its wider sense this includes considerations of multiple inter-relating factors of ensuring adequate bone support, implant location number, length, distribution and inclination, splinting, vertical dimension aesthetics, static and dynamic occlusal schemes and more. Current concepts and research on occlusal loading and overloading are reviewed together with clinical outcome and biomechanical studies and their clinical relevance discussed. A comparison between teeth and implants regarding their proprioceptive properties and mechanisms of supporting functional and parafunctional loading is made and clinical applications made regarding current concepts in restoring the partially edentulous dentition. The relevance of occlusal traumatism and fatigue microdamage alone or in combination with periodontal or peri-implant inflammation is reviewed and applied to clinical considerations regarding splinting of adjacent implants and teeth, posterior support and eccentric guidance schemes. Occlusal restoration of the natural dentition has classically been divided into considerations of planning for sufficient posterior support, occlusal vertical dimension and eccentric guidance to provide comfort and aesthetics. Mutual protection and anterior disclusion have come to be considered as acceptable therapeutic modalities. These concepts have been transferred to the restoration of implant-supported restoration largely by default. However, in light of differences in the supporting mechanisms of implants and teeth many questions remain unanswered regarding the suitability of these modalities for implant supported restorations. These will be discussed and an attempt made to provide some current clinical axioms based where possible on the best available evidence.

Scintigraphic imaging of adrenal disease

The nuclear medicine approach to adrenal imaging spans six decades with radiopharmaceuticals designed to take advantage of the unique characteristics of the functional divisions of the gland, substrate accumulation, hormone biosynthesis, receptor-ligand interactions and pharmacologic manipulation of mechanisms of central control. The recent introduction of hybrid imaging techniques that combine high resolution anatomy with the functional maps derived from the scintigraphic images is yet another step in the evolution of integrated imaging techniques that can be used to diagnostic advantage in the evaluation of disease of the adrenal gland.

Association between asthma and serum adiponectin concentration in women

BACKGROUND

The association of murine asthma with adiposity may be mediated by adiponectin, an anti-inflammatory adipokine with reduced serum concentrations in obese subjects. A study was undertaken to examine whether the serum adiponectin concentration is associated with human asthma and whether it explains the association between adiposity and asthma, particularly in women and in premenopausal women.

METHODS

A cross-sectional analysis was performed of 2890 eligible subjects at year 15 of the Coronary Artery Risk Development in Young Adults (CARDIA) cohort and its YALTA ancillary study who had either current asthma or never asthma at that evaluation. Obesity was defined as body mass index (BMI) >or=30 kg/m(2). Multivariable logistic regression analysis was performed with current asthma status as the dependent variable.

RESULTS

Women, but not men, with current asthma had a lower mean unadjusted serum adiponectin concentration than those with never asthma (p<0.001; p for sex interaction <0.001). Similarly, current asthma was related to obesity only in women (OR 3.31, 95% CI 2.00 to 5.46, p for sex interaction = 0.004); this association was little affected by adjusting for serum adiponectin. The prevalence of current asthma in premenopausal women was reduced in the highest compared with the lowest tertile of serum adiponectin concentration (OR 0.46, 95% CI 0.26 to 0.84, p = 0.03), after adjusting for BMI. However, the interaction between serum adiponectin concentration and BMI category on current asthma status was not significant in premenopausal women or women overall.

CONCLUSIONS

A high serum adiponectin concentration may protect against current asthma in premenopausal women but does not explain the association between asthma and adiposity.

The role of 18F-FDG PET/CT in detecting metastatic deposits of recurrent medullary thyroid carcinoma: a prospective study

AIM

To assess the diagnostic role of 18F-FDG PET/CT performed with a hybrid tomograph in the detection of tumoral deposits of recurrent medullary thyroid carcinoma (MTC).

METHODS

Nineteen MTC patients with elevated serum calcitonin levels (58-1350 pg/ml) after first treatment were enrolled (11 F, 8 M, mean age 53.4 years, 14 sporadic MTC, 5 MEN-related MTC). All patients had previously undergone total thyroidectomy and lymphoadenectomy. When referred to us, they were studied with ultrasound (US), 18F-FDG PET/CT, (111)In-pentetreotide scan, and contrast-enhanced whole-body CT (c.e. CT). In 4 patients with equivocal abdominal findings at 18F-FDG PET/CT and/or at c.e. CT, laparoscopy was also performed.

RESULTS

18F-FGD PET/CT depicted metastases in 15 patients, 111In-pentetreotide in 8, c.e. CT in 11, US in 6. In 2 patients, liver micrometastases were detected at laparoscopy only. At a lesion-by-lesion analysis, 18F-FDG PET/CT visualized a total of 26 metastatic deposits, c.e. CT 18, 111In-pentetreotide 12, US 8. Final diagnosis was obtained by cytological or surgical findings. Four patients with evidence of limited metastatic spread to neck/upper mediastinum were re-operated, and in 2 of them serum calcitonin levels normalized.

CONCLUSIONS

In our study, 18F-FDG PET/CT was the most sensitive imaging modality in detecting metastases in recurrent MTC patients with increased serum calcitonin levels. Moreover, 18F-FDG PET/CT was useful in some patients to plan a more accurate re-operation. From a diagnostic point of view, a multimodality imaging approach is recommended in recurrent MTC, especially based on the combination of c.e. CT and 18F-FDG PET/CT.

PET in genitourinary tract cancers

Genitourinary (GU) tract cancers comprise a variety of tumors, which includes some of the most common malignancies in men and women. As a result of the importance of GU neoplasms and the success of positron emission tomography (PET) in imaging and staging cancer, PET with fluorodeoxyglucose (FDG) has been used to depict and stage ovarian, cervical and testicular cancers. The early success of FDG PET in imaging GU tumors is tempered by the fact that some neoplasms of GU origin do not accumulate sufficient FDG for successful imaging. As a result, alternative agents, such as [11C]choline and [11C]acetate, have been used to image prostate cancer and may have utility in bladder cancer, while other PET agents are currently under active evaluation for this and other GU neoplasms. In this paper, we review the current literature and our experience in role of PET in imaging cancers of the GU tract.

99mTc-sestamibi radio-guided surgery of loco-regional 131Iodine-negative recurrent thyroid cancer

AIM

We report here our experience in a larger series of differentiated thyroid cancer (DTC) patients who had been treated by (99m)Tc-sestamibi radio-guided surgery (RGS) for (131)Iodine ((131)I)-negative loco-regional recurrent disease.

METHODS

Fifty-eight patients with loco-regional (131)I-negative recurrent disease from DTC were studied with (99m)Tc-sestamibi directed RGS using a hand-held 11-mm gamma probe as an intra-operative detector. Patients were selected for RGS on the basis of (a) progressive increase of serum thyroglobulin (Tg) levels after first treatment during follow-up, (b) negative high dose (100 mCi, 3.7 GBq) (131)I whole-body scan, and (c) positive pre-operative (99m)Tc-sestamibi scintigraphy for the presence of loco-regional recurrent disease. There were 41 papillary (1 "tall" cell variant), 13 follicular and 4 Hürthle cells tumours. In 14 patients thyroid cancer recurred in the thyroid bed while cervical lymph node metastases were found in 37 patients, and 7 patients had recurrent disease both in the thyroid bed and in cervical lymph nodes.

RESULTS

At bilateral neck exploration, 147 metastatic foci ranging from 4 mm to 51 mm in largest diameter (mean tumour diameter=17.3+/-9.5mm) were removed. Eighty-five of them (58%) had been pre-operatively identified at (99m)Tc-sestamibi scintigraphy. After RGS, serum Tg levels normalised in 43 of 58 patients (serum Tg<2 ng/ml--they were considered disease-free), serum Tg remained slightly increased in 12 patients without evidence of metastatic disease at scintigraphic and radiologic imaging (serum Tg<10 ng/mg--they were considered living with microscopic disease), while serum Tg significantly increased up to values>900 ng/ml in 3 patients who developed lung metastases. The mean lesion to background (99m)Tc-sestamibi uptake ratios decreased in all 58 patients (p<0.0001). Post-surgical follow-up ranged 6-72 months (mean+/-SD=29.6+/-13.5 months). The operating surgeon assessed RGS as very useful in 14 patients in whom metastatic foci were embedded in fibrotic tissues or located behind blood vessels, useful in 22 patients, moderately useful 17 patients and not useful in 5 patients.

CONCLUSION

Our data suggest that a (99m)Tc-sestamibi intra-operative gamma probe can be used to identify and guide resection of recurrent loco-regional tumour in DTC patients with (131)I-negative loco-regional metastatic foci.

Iodine-131 radio-guided surgery in differentiated thyroid cancer: Outcome on 31 patients and review of the literature

In the present study we investigated the role of radio-guided surgery with Iodine-131 (I-131) in a group of 31 patients with differentiated thyroid cancer (DTC) and loco-regional recurrent disease. The principal inclusion criterion for I-131 radio-guided surgery in our protocol was the presence of an I-131 positive loco-regional disease relapse after previous total thyroidectomy and at least 2 ineffective conventional I-131 treatments. The protocol we used consisted of the following steps. Day 0: all patients were hospitalized and received a therapeutic 3.7 GBq (100 mCi) dose of I-131 after thyroid hormone therapy withdrawal in condition of overt hypothyroidism (serum TSH levels>30 microUI/ml). Day 3: a whole body scan following the therapeutic I-131 dose (TxWBS) administration was acquired. Day 5: neck surgery was performed through a wide bilateral neck exploration using a 15-mm collimated gamma probe, measuring the absolute intra-operative counts and calculating the lesion to background (L/B) ratio. Day 7: post-surgery TxWBS was performed using the remaining radioactivity to evaluate the completeness of tumoral lesions extirpation. The final histologic examination showed the presence of 184 metastatic foci; among them, 98 (53.2%) were evident by both TxWBS and gamma probe evaluation, 76 (41.3%) were demonstrated only by gamma probe, and 10 (5.4%) were negative by both TxWBS and gamma probe evaluation. During follow-up (8 months to 4.9 years, mean 2.8 years), DxWBS, serum Tg levels off l-T4, and US showed absence of loco-regional disease in 25 patients (80.6%) while 6 patients had persistent disease. In conclusion, this protocol allowed us to identify neoplastic foci with high sensitivity and specificity, enabling us to remove loco-regional I-131 disease recurrences resistant to previous conventional I-131 therapies. Furthermore, the gamma probe allowed detection of some additional tumoral foci in sclerotic areas or located behind vascular structures that were not visualized at the pre-surgery TxWBS evaluation.

Somatostatin receptor PET imaging with Gallium-68 labeled peptides

Imaging somatostatin receptor status with 68Ga labeled peptides has progressed rapidly over the last several years. It has generated great interest, and stimulated further research into the development of DOTA-derivative peptides. It has expanded our knowledge of receptor imaging and enhanced our appreciation of the difference between receptor-based and metabolic imaging, as well as more in-depth evaluation of tumor biology. The availability of the 68Ge/68Ga generator provides an attractive alternative to cyclotron-based positron-emitters, especially if kit-based radiopharmaceutical formulations based upon 68Ga are developed in the future.

PET in the diagnostic evaluation of adrenal tumors

Early experience with positron emission tomography (PET) has provided exciting results in the evaluation of a broad spectrum of neoplasms, to include primary adrenal tumors, their metastases and metastatic disease to the adrenal glands. By virtue of the well-recognized propensity of malignancies to preferentially use glycolysis as an important energy source and the stimulation of mechanisms designed to absorb substrate glucose, the glucose analog, [18F]fluorodeoxyglucose, has become a successful radiopharmaceutical in the scintigraphic evaluation of adrenal tumors. Building upon prior experience gained with imaging the adrenal gland, other positron-labeled radiopharmaceuticals are finding their way into clinical use. The 11b-hydroxylase inhibitor, metomidate labeled with 11C has been used to scintigraphically identify tissues of adrenocortical origin, to accurately identify recurrent and metastatic adrenocortical carcinoma and may be useful in assessing the malignant potential of these tumors and predicting survival in afflicted patients. Adrenomedulla imaging with 11C- and 18F-labeled catecholamines and catecholamine analogs draws heavily from the experience gained from predecessor compounds, labeled with single photon emitting isotopes and, in some instances, single photon emission tomography, and has been shown to depict with high efficacy pheochromocytomas, neuroblastomas and other neoplasms of neural crest origin. Additional structural and functional information provided by computed tomography (CT), performed as part of hybrid PET/CT imaging directly complements PET and adds measurable diagnostic value in the evaluation of adrenal tumors.

18F-FDG PET/CT fusion imaging in paediatric solid extracranial tumours

This paper aims at discussing the utility of 18F-FDG PET/CT in the evaluation of paediatric solid extracranial tumours. Following a brief discussion of the basic principles and methodology of PET/CT system, it reviews the main characteristics of the tumours that can be visualised with 18F-FDG PET and presents examples of cases where the combined use of 18F-FDG PET/CT fusion imaging helped in the management of patients. It will also discuss the physiologic biodistribution of 18F-FDG, outlining the normal variants in the paediatric patients that may lead to misinterpretation.

Accelerated platelet activation in Asian Indians with diabetes and coronary artery disease--The Chennai Urban Population Study (CUPS-13)

AIM

To assess platelet activation in south Indian type 2 diabetic subjects with and without CAD.

METHODS

Four groups of subjects were studied; Group 1 comprised of non-diabetic subjects without coronary artery disease (CAD) (n = 30). Type 2 diabetic subjects without CAD formed Group 2 (n = 30); Group 3 comprised of type 2 diabetic subjects with CAD (n = 30) and Group 4 consisted of non- diabetic subjects with CAD (n=14). CAD was diagnosed based on coronary angiographic evidence of severe double or triple vessel disease. Platelet activation was tested after an overnight fast in blood obtained from a bleeding wound at 1 minute post-incision (wound-induced activation) as well as venous blood stimulated in vitro with collagen, using whole blood flow cytometry. In subjects with CAD, aspirin was withdrawn for 7 days and nitrates for 24 hours.

RESULTS

Collagen induced GP IIb/IIIa binding was significantly higher among diabetic subjects with (28.10 +/-19.89; p<0.05) and without CAD (21.02+/-19.62; p<0.05) and non-diabetic subjects with CAD (23.89+/-15.65; p<0.05) compared to non-diabetic subjects without CAD (11.69+/-13.69). Regression analysis showed collagen induced GP IIb/IIIa binding to be significantly associated with CAD [odds ratio (OR): 1.029, p = 0.025] and diabetes (OR: 1.037, p = 0.007).

CONCLUSION

Increased platelet activation is seen in urban south Indians with diabetes and CAD.

Effect of low intensity laser irradiation on surgically created bony defects in rats

Low intensity lasers have been used by clinicians to improve healing and reduce pain in humans. Lasing also results in new bone formation around hydroxyapatite implants and a significant increase in the total bone area. However, the exact mechanism of cell biostimulation by laser is still unclear. This study biochemically assessed the effects of low intensity laser (Gallium-Arsenide) using 4 and 22.4 mW cm(-2) power density on the bone healing process after surgically creating bony cavities in rat mandibles. Rats (n = 24) were divided into two groups each treated with specific energy, 4 or 22.4 mW cm(-2), for 3 min each day post-surgery. Surgical cavities were created on both sides of the mandible: the left served as an untreated control, the right was treated with laser. All rats were sacrificed after 1, 2 and 4 weeks of treatment. In the newly formed callus, accumulation of radiocalcium and alkaline phosphatase activity was measured to indicate osteogenic activity. One-way anova with repeated measures showed that the low intensity laser using 4 mW cm(-2) power density significantly increased radiocalcium accumulation from 2 weeks post-surgery, whereas 22.4 mW cm(-2) had no effect. No changes were noted in the activity of alkaline phosphatase with the laser treatment. These results suggest that laser therapy of low power density is effective on the bone healing process in artificially created osseous cavities by affecting calcium transport during new bone formation.

Tacrolimus-associated hypomagnesemia in renal transplant recipients

BACKGROUND

Since hypomagnesemia occurs frequently in tacrolimus treated patients, we studied the correlation between renal magnesium wasting and tacrolimus blood levels in renal transplant patients.

METHODS

Serum magnesium, fractional excretion of magnesium (FEMg), and 24-hour urinary excretion of magnesium were measured in 41 transplant patients and 10 healthy volunteers for correlation with tacrolimus level.

RESULTS

Of tacrolimus-treated patients, 43% displayed hypomagnesemia. FEMg (7.42+/-3.59% versus 1.88+/-0.43%) and 24-hour urinary excretion (112.36+/-51.43 mg/dL versus 6.7+/-2.79 mg/dL) were significantly higher among tacrolimus-treated patients than controls. Magnesium replacement did not influence FEMg or 24-hour urinary magnesium excretion. Tacrolimus level was the best predictor of 24-hour urinary magnesium excretion and FEMg. Serum magnesium levels correlated inversely with tacrolimus concentrations and creatinine clearance.

CONCLUSION

Hypomagnesemia in renal transplant recipients results from renal magnesium wasting. Tacrolimus levels and renal function impact on the excess renal magnesium excretion. Studies of longer duration are warranted to assess the long-term effects of this early posttransplant hypomagnesemia.

Supra-clavicular lymph node metastatic spread in patients with ovarian cancer disclosed at 18F-FDG-PET/CT: an unusual finding

Tumoral dissemination of ovarian cancer most commonly occurs through the intra-peritoneal route; nevertheless, although it is rare, ovarian cancer may also metastasise through the lymphatic channels. Lymphatic diffusion of ovarian cancer usually involves pelvic and retro-peritoneal lymph nodes. Extra-abdominal lymph nodes are rarely involved and their detection may represent a challenge for the oncologist. We describe here two patients studied for ovarian cancer by [18F]fluoro-2-deoxy-D-glucose (18F-FDG) positron emission tomography (PET)/computed tomography (CT): one case during pre-operative staging, the other for restaging after surgery. In both cases PET examination identified extraabdominal lymph node tumoral spread in the left supra-clavicular space; biopsy led to a final diagnosis of recurrent ovarian cancer. Previous reports in the literature on tumoral spread of ovarian cancer to the supra-clavicular nodes are rare, however this possible site of metastatic involvement has to be kept in mind by oncologists and our data show that the 18F-FDG PET/CT may be useful to disclose this unusual supra-diaphragmatic lymphatic diffusion of metastatic lymphatic ovarian cancer.

New approaches for genotyping paraffin wax embedded breast tissue from patients with cancer: the Iowa women's health study

BACKGROUND

The use of paraffin wax embedded tissue samples as a source of DNA for genotype analysis has been limited because of difficulties in DNA extraction and single nucleotide polymorphism (SNP) analysis.

AIMS

To test the feasibility of applying the combination of a commonly used DNA isolation procedure, PureGene, and a high throughput SNP analysis method, the polymerase chain reaction (PCR)-INVADER assay, to genotype several types of paraffin wax embedded breast tissues.

METHODS

Twenty formalin fixed, paraffin wax blocks were obtained from five participants in the Iowa women's health study. Each participant provided several types of tissue including normal lymph node, normal nipple/areola tissue, inflammatory/fibrotic breast tissue, or normal breast tissue, and tumour tissue.

RESULTS

Good quality DNA (260/280 ratio >1.6) was obtained from all tissues. Normal lymph nodes yielded the largest amount of DNA (97.1 mug). DNA obtained from the samples was tested for a germline C1183T polymorphism in the MnSOD gene by three methods-PCR-RFLP (restriction fragment length polymorphism), INVADER assay, and PCR-INVADER assay. Of the 20 samples, PCR-RFLP genotyped 16, the PCR-INVADER assay 18, and the INVADER assay two. This methodology was then used to analyse five additional genotypes and confirmed the general applicability of the method.

CONCLUSIONS

This study demonstrated the feasibility of (1) using several paraffin wax embedded breast tissues as a source of DNA for germline genetic analysis, with lymph nodes providing the highest yield, and (2) using the combination of a common extraction method with a high throughput SNP analysis method, the PCR-INVADER assay.

Controversies in diagnostic approaches to the indeterminate follicular thyroid nodule

In this paper we review the controversies in diagnostic approaches to follicular thyroid nodules with indeterminate cytology. The authors consider some of the controversies surrounding the indeterminate follicular thyroid nodule, including the definition and the postoperative outcome. Among the techniques that may improve preoperative diagnostic accuracy are large needle aspiration biopsy and immunohistochemistry for galectin-3.

‘Low dose’ 99mTc-Sestamibi for radioguided surgery of primary hyperparathyroidism

AIM

In this study, we evaluated the efficacy of low dose (99m)Tc-Sestamibi administration for radioguided parathyroid surgery in patients with primary hyperparathyroidism (PHPT).

METHODS

Three hundred consecutive PHPT patients were studied between September, 1999 and July, 2003. Pre-operative work-up included (99m)Tc-pertechnetate/(99m)Tc-Sestamibi subtraction scintigraphy and high resolution ultrasonography (US). 37MBq of (99m)Tc-Sestamibi was injected i.v. in the operating suite approximately 10 min prior to the beginning of the surgical procedure for intraoperative radiolocalization; quick parathyroid hormone (QPTH) assays were performed.

RESULTS

Two hundred and seven of the 211 patients selected for minimally-invasive radioguided parathyroidectomy (MIRP) were successfully treated for a solitary parathyroid adenoma (PA) through a 2-2.5 cm skin incision (mean operative time 35 min, mean hospital stay 1.2 days). In the 89 patients selected for traditional bilateral neck exploration (BNE), radioguided surgery was not as successful in the identification of the PA, especially in patients with (99m)Tc-Sestamibi-avid thyroid nodules. Nevertheless, the combination of probe and QPTH measurement was very helpful in patients with multigland disease.

CONCLUSIONS

Low-dose (99m)Tc-Sestamibi administered few minutes before surgery is sufficient for MIRP in patients with high likelihood of a solitary PA and without concomitant (99m)Tc-Sestamibi-avid thyroid nodules. The combination of radioguided surgery and QPTH measurements is very useful in the early identification of unanticipated multigland disease.

Controversies on minimally invasive procedures for radio-guided surgery of parathyroid tumours

The definitive treatment of primary hyperparathyroidism (PHPT) is the surgical approach which traditionally consists of bilateral neck exploration with visualization of at least 4 parathyroid glands and removal of the enlarged ones. However, the most frequent cause of PHPT is a solitary parathyroid adenoma so that a limited neck exploration in order to remove the solitary adenoma alone appears adequate to many surgeons. The recent significant improvements achieved in the pre-operative parathyroid localization techniques, mainly the parathyroid scintigraphy, and the introduction in surgical practice of measurement of quick parathyroid hormone, endoscopic procedures, and intra-operative gamma probes used together specific radiopharmaceuticals allowed to offer the PHPT patient a limited neck exploration as the unilateral neck exploration and the minimally invasive parathyroidectomy. The present article deals with the role of the intra-operative gamma probes used together with specific radio-pharmaceuticals, discussing the principal advantages and disadvantages of each currently used radio-guided approach.

BIOACTIVE COMPOUNDS IN NUTRITION AND HEALTH-RESEARCH METHODOLOGIES FOR ESTABLISHING BIOLOGICAL FUNCTION: The Antioxidant and Anti-inflammatory Effects of Flavonoids on Atherosclerosis

Identifying bioactive compounds and establishing their health effects are active areas of scientific inquiry. There are exciting prospects that select bioactive compounds will reduce the risk of many diseases, including chronic diseases such as cardiovascular disease. Recent findings have established that cardiovascular disease is a disease of inflammation, and consequently is amenable to intervention via molecules that have anti-inflammatory effects. In addition, research demonstrating adverse effects of oxidants on atherogenesis raises the possibility that antioxidants can confer cardioprotective effects. This review provides an overview of research approaches that can be used to unravel the biology and health effects of bioactive compounds. Because of the number of bioactive compounds and the diversity of likely biological effects, numerous and diverse experimental approaches must be taken to increase our understanding of the biology of bioactive compounds. Recognizing the complexity of this biology, sophisticated experimental designs and analytical methodologies must be employed to advance the field. The discovery of novel health effects of bioactive compounds will provide the scientific basis for future efforts to use biotechnology to modify/fortify foods and food components as a means to improve public health.

Chewing side preference as a type of hemispheric laterality

Chewing side preference is a factor that could effect prosthodontic treatment. The purpose of this study was to determine whether chewing side was another type of hemispheric lateralization comparable with footedness, handedness, eyedness and earedness. Chewing side preference was tested in 189 subjects of whom 84 were partially edentulous, 98 had a full compliment of dental units (81 included implant-supported restoration restoring the missing teeth and 17 with fully intact dentitions), and seven were fully edentulous, restored with complete dentures. Laterality tests were carried out for the first cycle of mastication, handedness, footedness, earedness and eyedness and patient questionnaire. Most patients preferred chewing on the right side (78b3%) and were right sided. Chewing side preference correlated with other tested hemispherical lateralities. Missing teeth, occlusion type, lateral guidance, gender, implant-supported restorations and complete dentures do not affect the side preference for chewing. This presents a strong argument that chewing side preference is centrally controlled and provides food for thought regarding its significance in prosthodontics.

Gamma-glutamyltransferase and diabetes--a 4 year follow-up study

AIMS/HYPOTHESIS

Gamma-glutamyltransferase (GGT) is located on the external surface of most cells and mediates the uptake of gluthathione, an important component of intracellular antioxidant defenses. An increase in GGT concentration has been regarded as a marker of alcohol consumption or liver disease. However, more subtle gradations in GGT could be informative because its expression is enhanced by oxidative stress and it could be released by several conditions inducing cellular stress. Recently, serum GGT concentrations have been associated with many cardiovascular disease risk factors or components of the insulin resistance syndrome. We did a prospective study with the hypothesis that serum GGT is a predictor of incident diabetes.

METHODS

A total of 4,088 healthy men working in a steel manufacturing company were examined in 1994 and 1998. Diabetes was defined as a serum fasting glucose concentration of more than 126 mg/dl or the use of diabetes medication.

RESULTS

There was a strong dose-response relation between serum GGT concentrations at baseline and the incidence of diabetes. In contrast to the 31% of men with GGT concentrations under 9 U/l, adjusted relative risks for incidence of diabetes for GGT concentrations 10-19, 20-29, 30-39, 40-49, and over 50 U/l were 8.0, 13.3, 12.6, 19.6 and 25.8, respectively. The associations of age and BMI with incident diabetes became stronger the higher the value of baseline serum GGT concentration.

CONCLUSION/INTERPRETATION

This study suggests that an increase in GGT concentration within its physiological range is a sensitive and early biomarker for the development of diabetes.

Scintigraphy of acute inflammatory lesions in rats with radiolabelled recombinant human neutrophil-activating peptide-2

Radiolabelled recombinant human interleukin-8 (IL-8) with its homologue neutrophil-activating peptide-2 (NAP-2) have been compared for imaging acute sterile inflammatory lesions in rats. 125I-IL-8 and 125I-NAP-2 were prepared by reaction with chloramine-T and injected intravenously into male rats bearing subcutaneous carrageenan abscesses in their left hindlimbs. Left hindlimb and right hindlimb activities were determined from serial total-body scintigrams between 1 h and 96 h post-injection as regional per cent injected activity corrected for physical decay (%IA). Time-activity curves for 125I-IL-8 and 125I-NAP-2 in the carrageenan-containing left hindlimbs were similar in that both peaked at 1-3 h post-injection (IL-8, 4.9+/-0.5%IA; NAP-2, 4.8+/-1.9%IA) and decreased exponentially thereafter. However, while the lesioned-to-control limb activity ratio (L/C) for 125I-IL-8 only approximately doubled during the imaging period (1.7+/-0.3 at 1 h vs 3.7+/-1.0 at 24 h post-injection), L/C for 125I-NAP-2 more than tripled, rising from 1.5+/-0.4 at 1 h to 5.3+/-0.7 by 72 h post-injection. It is concluded that while both radiolabelled IL-8 and NAP-2 may prove useful for clinical imaging, radiolabelled NAP-2 may provide better discrimination of inflammatory lesions from normal tissue at later times post-injection.

Radioisotope diagnosis and therapy of malignant pheochromocytoma

The availability of radiopharmaceuticals to depict primary malignant pheochromocytoma and its metastases has markedly changed the approach to these unusual cancers. Whole body screening afforded by scintigraphy allows remote tumor involvement to be identified and provides staging information necessary to guide subsequent therapy. The avid accumulation by malignant pheochromocytoma of some radiopharmaceuticals used for scanning has shown promise in therapeutic trials. In this paper, we discuss radiopharmaceuticals presently employed in malignant pheochromocytoma for both diagnostic and therapeutic uses and potential future compounds that may find their way into clinical practice in the approach to these and other related neoplasms.

Imaging of human infection with (131)I-labeled recombinant human interleukin-8

The chemotactic cytokine interleukin-8 (IL-8) plays an important role in attraction and activation of polymorphonuclear leukocytes in infection and inflammation. A pilot study was conducted to determine if radiolabeled IL-8 would depict infection in humans.

METHODS

Human recombinant IL-8 (rhIL-8) labeled with (131)I (specific activity, 0.4-0.7 MBq [11-18 microCi] (131)I/microg IL-8) was injected intravenously into 8 diabetic patients with active foot infections and evidence of osteomyelitis, 2 patients with successfully treated osteomyelitis, and 1 patient with cellulitis of the thumb.

RESULTS

Focal accumulation of (131)I-rhIL-8 was seen in 8 of 8 patients with active foot infection and diffuse uptake was seen in the thumb of the 1 patient with cellulitis. In the 2 patients with successfully treated bone infection, multiphase (99m)Tc-hydroxyethylene diphosphonate bone scans were negative early, but late-phase (>3 h) uptake depicted degenerative lesions that did not image with (131)I-rhIL-8.

CONCLUSION

(131)I-rhIL-8 accumulates rapidly within infected foci in osteomyelitis and cellulitis but not in successfully treated infections or degenerative joint disease.

Diagnostic targeting of temporomandibular disorders

This article describes a diagnostic chart that is organized for a versatile representation of various conditions of temporomandibular disorders (TMD). It facilitates the grading of disorder severity and visualization of probable mutual effects between groups of disorders. It also enhances the clinician's awareness of potential systemic involvement in TMD by incorporating it into the chart. Comparison of charts completed at consecutive examinations is helpful for the assessment of disorder progression, regression or for the refining of diagnoses.

Stress distribution around maxillary implants in anatomic photoelastic models of varying geometry. Part I

STATEMENT OF PROBLEM

It is unclear which implant inclination and position are most favorable in relation to the supporting anatomy and loading direction in the maxilla.

PURPOSE

This study was designed to examine stress distribution around implants in a 2-dimensional photoelastic anatomic model.

MATERIAL AND METHODS

Two 2-dimensional photoelastic models were prepared with opposing 8-degree cylinder metal implant and molar teeth analogues. A frontal anatomic sectional plate model based on a CT section at the first molar was symmetrically loaded through its long axis. A midfacial rectangular model based on the same section was loaded in a different direction with varying supporting geometries.

RESULTS

Stress distribution around the maxillary implant was highest in the buccal concavity at the apical buccal third and in the lingual concavity on intercuspal loading. No stress concentration occurred at the implant apex under the sinus for axial and nonaxial loading in both anatomic model geometries. On lateral loading, stress concentration was observed at the buccal concavity and at the implant neck. In the midfacial block model, principal stresses were concentrated at the maxillary implant neck on nonaxial loading and at the apex on axial loading.

CONCLUSION

This 2-dimensional skull model showed different patterns of stress distribution among the maxillary implant, mandibular implant, and teeth. The highest principal stress concentration was seen at the buccal concavity of the maxillary implant; this may play a role in osseointegration with highly angled implants in the posterior maxilla. Differences in stress distribution between anatomic and nonanatomic models showed how the supporting geometry (for example, sinus/nasal anatomy), boundary conditions, and loading direction influence stress distribution.

Stress distribution around maxillary implants in anatomic photoelastic models of varying geometry. Part II

STATEMENT OF PROBLEM

Insufficient buccal bone volume can be a significant problem when loading dental implants in the maxilla. Increased potential for buccal fenestration and dehiscence can result in an exposed implant surface, mucosal irritation, decreased support, and potential implant failure.

PURPOSE

The objective of this study was to model the stress distribution around maxillary implants by comparing simulated occlusal loading of maxillary implants in a 2-dimensional photoelastic anatomic model and a dry skull model.

MATERIAL AND METHODS

Two model systems were used. First, a 2-dimensional photoelastic anatomic frontal skull sectional model was prepared in the first molar region. Left and right maxillary metal cylinder implant analogues inclined at 0 and 25 degrees to the sagittal plane were loaded in simulated intercuspation. Second, a dry skull lined with a photoelastic coating on the buccal aspect over an embedded cylinder implant was prepared in the first molar region. Principal stress concentration was photographed on axial and nonaxial implant loading.

RESULTS

On simulated intercuspal loading, maximum stress concentration occurred at the buccal concavity in both the 2-dimensional anatomic photoelastic and skull models. There was no stress concentration at the apices of the maxillary implants in the 2-dimensional model. On lateral loading of the skull model, stress was distributed along the entire buccal aspect of bone adjacent to the implant, with a higher concentration at the buccal concavity.

CONCLUSION

Preservation of buccal supporting bone volume is desirable to obtain a physiological modeling response and to enhance the facial plate. Insufficient bone volume may result in buccal fenestration or dehiscence, which can precipitate mucosal irritation, decreased support, and potential implant failure.

Interactions between apolipoprotein E gene and dietary alpha-tocopherol influence cerebral oxidative damage in aged mice

Cerebral oxidative damage is a feature of aging and is increased in a number of neurodegenerative diseases. We pursued the gene-environment interaction of lack of apolipoprotein E (apoE) and modulation of dietary alpha-tocopherol on cerebral oxidative damage in aged male and female mice by quantifying the major isomers of cerebral isoprostanes, derived from arachidonic acid (AA) oxidation, and neuroprostanes, derived from docosahexaenoic acid (DHA) oxidation. Mice fed alpha-tocopherol-deficient, normal, or -supplemented diet had undetectable, 4486 +/- 215, or 6406 +/- 254 ng of alpha-tocopherol per gram of brain tissue (p < 0.0001), respectively. Two factors, male gender and lack of apoE, combined to increase cerebral AA oxidation by 28%, whereas three factors, male gender, lack of apoE, and deficiency in alpha-tocopherol, combined to increase cerebral DHA oxidation by 81%. alpha-Tocopherol supplementation decreased cerebral isoprostanes but not neuroprostanes and enhanced DHA, but not AA, endoperoxide reduction in vivo and in vitro. These results demonstrated that the interaction of gender, inherited susceptibilities, and dietary alpha-tocopherol contributed differently to oxidative damage to cerebral AA and DHA in aged mice.

Three-dimensional finite element analysis of the facial skeleton on simulated occlusal loading

Development of predictive models of occlusal loading of the facial skeleton will be of value for prosthetic design in oral rehabilitation. A 3-D finite element (FE) model of a human skull, based on CT scans, was constructed to analyse strain and stress distribution in the facial skeleton caused by simulated occlusal loading. Vertical loads were applied simulating loading of the full maxillary arch and unilateral single point occlusal loading of maxillary molar, pre-molar, canine and incisor sites. Strain and stress regimes from Von Mises (VM) failure criteria and extension and compression diagrams showed even distribution of strain following loading of the full maxillary arch throughout the facial elements. For individual points, the highest VM concentrations were consistently located on the facial aspect several mm above the loading site. Strain trajectories divided into a 'V-shaped' pattern, from the loading point into medial and lateral branches with higher VM values in the medial. As the same load was applied from the posterior to anterior region, VM values increased on all facial areas. Strain patterns were less symmetric and there was an increase in strain in the alveolar arch and around the rim of the nasal cavity. The overall picture of the facial skeleton is of a vertical plate enabling it to withstand occlusal stresses by in-plane loading and bending in its own plane. The most efficient distribution of load was on maxillary full arch loading with the most unfavourable strain concentrations occurring on loading in the anterior region.

Induction of HL-60 cell differentiation by carotenoids

Recent observations indicated that carotenoids affected the proliferation and differentiation of certain cell lines. In the current experiments, beta-carotene and lutein were tested for the induction of differentiation with HL-60 cells, a bipotent promyelocytic leukemia cell line. Cultures were incubated with lutein (0.0-10.0 mumol/l), beta-carotene (0.0-10.0 mumol/l), and retinoic acid (0.0-1.0 mumol/l); retinoic acid incubations were positive controls for the differentiation of HL-60 cells into granulocytes. The carotenoid-incubated cultures developed significantly more (p < or = 0.05) differentiated cells than control cultures (vehicle alone). Morphology of the carotenoid-incubated cells indicated differentiation along the granulocytic pathway. The percentage of differentiated cells increased significantly throughout a seven-day incubation period to 25% (lutein), 35% (beta-carotene), and 75% (retinoic acid). A dose response was found for lutein (0.0-10.0 mumol/l), but not for beta-carotene. Throughout the incubation period, the percentage of differentiated cells in negative control cultures did not change, remaining at the initial background level (approximately 5%). These results provide evidence for carotenoid-induced differentiation of cells. Induction of cell differentiation by a carotenoid without (lutein) and with (beta-carotene) vitamin A activity suggested a vitamin A-independent mode of action for carotenoids in cell differentiation.

Solubilization of beta-carotene in culture media

Several methods were evaluated for the solubilization of supraphysiological concentrations of beta-carotene in culture media. The addition of beta-carotene in ethanol as 0.1% (vol/vol) of culture medium that contained 10% fetal bovine serum and incubation at 37 degrees C for 30 minutes solubilized approximately 50% of the added carotenoid. Solubilized beta-carotene concentrations from 3.06 to 36.4 mumol/l were obtained by this method. Ultracentrifugation studies localized the solubilized beta-carotene to low-density lipoproteins (67.0%) and high-density lipoproteins (24.9%). Other methods utilizing various amounts of fetal bovine serum, ethanol, and hexane as solvents did not significantly improve the solubilization of beta-carotene compared with the use of ethanol as 0.1% (vol/vol) of culture medium that contained 10% fetal bovine serum. Nonetheless, solubilization of supraphysiological concentrations of beta-carotene indicated the feasibility of preparing culture media containing physiological concentrations (approximately 0.5 mumol/l) of beta-carotene.

Serum carotenoids and markers of inflammation in nonsmokers

One explanation for discrepant results between epidemiologic studies and randomized trials of beta-carotene and cardiovascular disease may be a failure to consider inflammation as a confounder. To evaluate the potential for such confounding, the authors relate the serum concentrations of five carotenoids (alpha-carotene, beta-carotene, beta-cryptoxanthin, lycopene, and lutein/zeaxanthin) to levels of three inflammatory markers (C-reactive protein, fibrinogen, and white blood cell count) measured during the Third National Health and Nutrition Survey, 1988-1994. The analysis included 4,557 nonsmoking participants aged 25-55 years. Adjusted concentrations of all five carotenoids were significantly lower in those with C-reactive protein levels above 0.88 mg/dl (p = 0.001). There was a trend toward lower adjusted beta-cryptoxanthin concentrations with increasing level of fibrinogen (p value test for trend = 0.01), but other carotenoids were not related. Many of the carotenoid concentrations were lower among participants with high white blood cell counts. After log transformation, only adjusted mean beta-carotene levels were significantly lower in those with white blood cell counts above 7.85 x 10(9)/liter (p < 0.01). These cross-sectional data do not clarify the biologic relation between carotenoids and C-reactive protein but, to the extent that the carotenoids are associated with C-reactive protein levels, a carotenoid-heart disease association may be, in part, an inflammation-heart disease association.