Is there a future for adrenal scintigraphy?
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Adrenal Gland Diseases↗
Biomedical subjects
M D Gross
Publications and source records attributed to M D Gross.
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.
Animals↗
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.
Administration, Oral↗
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.
Adrenal Medulla↗
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.
Adult↗
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.
Diagnosis, Differential↗
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.
Birefringence↗
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.
Birefringence↗
Imaging of human infection with (131)I-labeled recombinant human interleukin-8.
UNLABELLED: 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.
Adult↗
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.
Acute-Phase Proteins↗
Uric acid and serum antioxidant capacity: a reaction to atherosclerosis?
BACKGROUND: the evidence of a potential beneficial role of antioxidants in preventing atherosclerotic disease is not entirely consistent. OBJECTIVE: to assess the longitudinal association of serum total antioxidant capacity and serum antioxidants with the presence of subclinical carotid atherosclerosis. METHODS: Prospective case-control study nested within an historical cohort. Cases were 150 individuals with elevated carotid intimal-medial thickness measured by B-mode ultrasound at the first two examinations of the Atherosclerosis Risk in Communities Study (1987-92). Controls were 150 age-gender-matched individuals with low carotid intimal-medial thickness. Serum antioxidant vitamins, uric acid, and serum total antioxidant capacity were measured in frozen serum samples collected from the same individuals in 1974 (13-15 years prior to the determination of case-control status). RESULTS: Compared to controls, atherosclerosis cases had significantly higher levels of serum total antioxidant capacity in 1974 than controls. This difference was almost entirely explained by increased serum concentration of uric acid in cases. In contrast with cross-sectional results, uric acid serum concentration in 1974, was significantly higher in cases than in controls, even after adjusting for the main cardiovascular risk factors. Cases had significantly lower levels of alpha-carotene in the 1974 sera than controls, but no other differences in serum antioxidant vitamin concentrations were observed. CONCLUSIONS: The higher serum uric acid concentration seemed associated with elevated total serum antioxidant capacity among individuals with atherosclerosis. This finding is consistent with experimental evidence suggesting that hyperuricemia may be a compensatory mechanism to counteract oxidative damage related to atherosclerosis and aging in humans.
Antioxidants↗
Artifacts, anatomical and physiological variants, and unrelated diseases that might cause false-positive whole-body 131-I scans in patients with thyroid cancer.
The whole body 131-I scan remains an important component in the postoperative treatment of patients with well-differentiated thyroid cancer. Because normal thyroid tissue remnants and residual or metastatic foci of well-differentiated thyroid cancer have the unique ability to concentrate, organify, and store 131-I, the whole body scan provides a depiction of those tissues that can be ablated with therapeutic doses of 131-I. Over time, it has become obvious that the whole body scan may also reveal foci of 131-i uptake owing to a wide variety of other causes. We provide a detailed pathophysiological classification of the artifacts, anatomic and physiological variants, and nonthyroidal diseases that may give rise to false-positive whole body scans in postoperative patients with thyroid cancer. These include ectopic foci of normal thyroid tissue; nonthyroidal physiological sites (eg, choroid plexus, salivary glands, gastric mucosa, urinary tract); contamination by physiological sections; ectopic gastric mucosa; other gastrointestinal abnormalities; urinary tract abnormalities; mammary abnormalities; serous cavities and cysts; inflammation and infection; nonthyroidal neoplasms; and currently unexplained causes. This article also provides a detailed review of the widely scattered English language literature in which these phenomena were originally described.
Artifacts↗
Effect of repeated closures on opening torque values in seven abutment-implant systems.
STATEMENT OF PROBLEM: Implant abutment screw joints tend to loosen under clinical conditions. During impression and prosthesis fabrication, repeated clinical closing and opening of abutment screws may cause component wear and decrease frictional fit of the mating parts, resulting in altered resistance to opening and potential for loss of preload in function. PURPOSE: This study recorded changes in opening torque values due to multiple consecutive closures at a constant torque within and between different abutment/implant (A/I) systems. MATERIAL AND METHODS: Repeated opening-closing cycles were used to simulate in vitro embedment relaxation and component wear of 7 A/I systems from 5 manufacturers. Screw opening torque values were recorded up to 200 consecutive closures at 20 N/cm. RESULTS: A progressive decrease in opening torque values was measured in all implant systems. Significant differences were found between A/I systems. Systems with morse tapered and spline connections consistently maintained a higher resistance to opening force. Percentage torque loss ranged from 3% to 20% on immediate opening, and from 4.5% to 36% for average of first 30 opening/closing cycles. CONCLUSION: Repeated opening and closing of implant abutment screws caused progressive loss of torque retention with variations between systems. This was probably due to a decrease in the coefficient of friction between the mating components.
Analysis of Variance↗
Antitumor activity of astaxanthin and its mode of action.
Astaxanthin, a carotenoid without vitamin A activity, may exert antitumor activity through the enhancement of immune responses. Here, we determined the effects of dietary astaxanthin on tumor growth and tumor immunity against transplantable methylcholanthrene-induced fibrosarcoma (Meth-A tumor) cells. These tumor cells express a tumor antigen that induces T cell-mediated immune responses in syngenic mice. BALB/c mice were fed astaxanthin (0.02%, 40 micrograms/kg body wt/day in a beadlet form) mixed in a chemically defined diet starting zero, one, and three weeks before subcutaneous inoculation with tumor cells (3 x 10(5) cells, 2 times the minimal tumorigenic dose). Three weeks after inoculation, tumor size and weight were determined. We also determined cytotoxic T lymphocyte (CTL) activity and interferon-gamma (IFN-gamma) production by tumor-draining lymph node (TDLN) and spleen cells by restimulating cells with Meth-A tumor cells in culture. The astaxanthin-fed mice had significantly lower tumor size and weight than controls when supplementation was started one and three weeks before tumor inoculation. This antitumor activity was paralleled with higher CTL activity and IFN-gamma production by TDLN and spleen cells in the astaxanthin-fed mice. CTL activity by TDLN cells was highest in mice fed astaxanthin for three weeks before inoculation. When the astaxanthin-supplemented diet was started at the same time as tumor inoculation, none of these parameters were altered by dietary astaxanthin, except IFN-gamma production by spleen cells. Total serum astaxanthin concentrations were approximately 1.2 mumol/l when mice were fed astaxanthin (0.02%) for four weeks and appeared to increase in correlation with the length of astaxanthin supplementation. Our results indicate that dietary astaxanthin suppressed Meth-A tumor cell growth and stimulated immunity against Meth-A tumor antigen.
Adjuvants, Immunologic↗
Cigarette smoking, alcohol consumption, and risk of ARDS: a 15-year cohort study in a managed care setting.
STUDY OBJECTIVE: To examine the association of cigarette smoking and alcohol consumption with hospital presentation of ARDS in a well-defined, multiethnic population. DESIGN: Retrospective cohort study. SETTING: Health maintenance organization in Northern California. PARTICIPANTS: A total of 121,012 health plan subscribers (54.2% women), aged 25 to 89 years. OUTCOME MEASURE: Hospital presentation of ARDS (validated by medical chart review) from baseline in 1979 to 1985 through the end of 1993 (median, 9.9 years). RESULTS: There were 56 cases of ARDS (33 in men, 23 in women). The case fatality rate was 39% in both genders. ARDS was independently related to increasing age (rate ratio of 10 years, 1.38; 95% confidence interval [CI], 1.12 to 1.71), to current smoking of < 20 cigarettes/d (rate ratio vs never cigarette smokers, 2.85; 95% CI, 1. 23 to 6.60), and to current cigarette smoking of > or = 20 cigarettes/d (rate ratio vs never smokers, 4.59; 95% CI, 2.13 to 9.88). No association was observed between alcohol consumption and ARDS. CONCLUSIONS: The results of this study suggest a relationship (with evidence of dose-response effect) between cigarette smoking and ARDS. Assuming a causal relationship, approximately 50% of ARDS cases were attributable to cigarette smoking.
Adult↗
PET imaging of adrenal cortical tumors with the 11beta-hydroxylase tracer 11C-metomidate.
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Adrenal Cortex Neoplasms↗
NMR investigation and secondary structure of domains I and II of rat brain calbindin D28k (1-93).
Calbindin D28k, a member of the troponin C superfamily of calcium-binding proteins, contains six putative EF hand domains but binds only four calcium-atoms: one at a binding site of very high affinity and three calcium-atoms at binding sites of lower affinity. The high-affinity site could be located within domain I while domains III, IV, and V bind calcium less tightly. The recombinant protein construct calb I-II (residues 1-93) comprising the first two EF hands affords a unique opportunity to study a pair of EF hands with one site binding calcium tightly and the second site empty. A series of heteronuclear 2D, 3D and 4D high-resolution NMR experiments were applied to calb I-II, and led to the complete assignment of the 1H, 13C and 15N resonances. The secondary structure of the protein was deduced from the size of the 3JHN-Halpha coupling constants, the chemical shift indices of 1Etaalpha, 13Calpha, 13C' and 13Cbeta nuclei and from an analysis of backbone NOEs observed in 3D and 4D NOESY spectra. Four major alpha-helices are identified: Ala13-Phe23, Gly33-Ala50, Leu54-Asp63, Val76-Leu90, while residues Ala2-Leu6 form a fifth, flexible helical segment. Two short beta-strands (Tyr30-Glu32, Lys72-Gly74) are found preceding helices B and D and are arranged in an anti-parallel interaction. Based on these data a structural model of calb I-II was constructed that shows that the construct adopts a tertiary structure related to other well-described calcium-binding proteins of the EF-hand family. Surprisingly, the protein forms a homodimer in solution, as was shown by its NMR characterization, size-exclusion chromatography and analytical ultra-centrifugation studies.
Amino Acid Sequence↗
Gallbladder bed photopenic halo on hepatobiliary scintigraphy: a sign of biliary leakage.
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Adult↗