Optical CT reconstruction of 3D dose distributions using the ferrous-benzoic-xylenol (FBX) gel dosimeter

In recent years, magnetic-resonance imaging of gelatin doped with the Fricke solution has been applied to the direct measurement of three-dimensional (3D) radiation dose distributions. However, the 3D dose distribution can also be imaged more economically and efficiently using the method of optical absorption computed tomography. This is accomplished by first preparing a gelatin matrix containing a radiochromic dye and mapping the radiation-induced local change in the optical absorption coefficient. Ferrous-Benzoic-Xylenol (FBX) was the dye of choice for this investigation. The complex formed by Fe3+ and xylenol orange exhibits a linear change in optical attenuation (cm-1) with radiation dose in the range between 0 and 1000 cGy, and the local concentration of this complex can be probed using a green laser light (lambda = 543.5 nm). An optical computed tomography (CT) scanner was constructed analogous to a first-generation x-ray CT scanner, using a He-Ne laser, photodiodes, and rotation-translation stages controlled by a personal computer. The optical CT scanner itself can reconstruct attenuation coefficients to a baseline accuracy of < 2% while yielding dose images accurate to within 5% when other uncertainties are taken into account. Optical tomography is complicated by the reflection and refraction of light rays in the phantom materials, producing a blind spot in the transmission profiles which, results in a significant dose artifact in the reconstructed images. In this report we develop corrections used to reduce this artifact and yield accurate dosimetric maps. We also report the chemical reaction kinetics, the dose sensitivity and spatial resolution (< 1 mm3) obtained by optical absorption computed tomography. The article concludes with sample dose distributions produced by "cross-field" 6 MV x-ray beams, including a radiosurgery example.     

Whole body bone resorption in the growing pig

Our knowledge of total body bone resorption during growth is limited. The primary purpose of this study was to determine if a commercially available bone resorption assay, developed for measuring human bone resorption, could be used to measure whole body bone resorption in young, growing pigs. A secondary purpose was to evaluate if this method could detect changes in bone resorption in response to certain dental appliances which have been shown to change mandibular and maxillary growth. Five growing 4-month-old male Hanford minipigs (Sus scrofa) were housed in metabolic cages for 24 h, every other day, over a period of 1 month. Three of the animals were fitted with a mandibular protrusive orthodontic appliance. Total 24 h urines were collected in which the concentration of creatinine and collagen type I N-telopeptide crosslinks (NTx, a marker of bone resorption) were measured. The NTx immunoassay was originally developed for the analysis of human urine. Pig bone was powdered, defatted, and decalcified, and the resulting powder digested with bacterial collagenase. The digest was screened for NTx content, in the same fashion as the pig urines. Bone extract and pig urines were cross-calibrated to a standard of adolescent human urine. This allowed calculation of the daily quantity of pig bone resorbed. Daily metabolite excretion was quite variable in these growing animals; for NTx the CV was 31%, for creatinine the CV was 25%. The mean daily quantities of bone resorption ranged between 26 and 46 grams of bone which amounted to 1.2-1.7% of estimated total skeletal mass. The protrusive appliances increased bone resorption significantly during the first two weeks of the trial. In conclusion: the NTx assay can be used to measure bone resorption in pigs; the assay is sensitive enough to indicate changes in bone resorption, such as those caused by an orthodontic mandibular protrusive appliance. During growth, bone resorption varies greatly from day to day. On average, every 24 h, 1.4% of the skeletal mass is resorbed.     

Ischemic fasciitis. Report of a case with fine needle aspiration findings

BACKGROUND: Ischemic fasciitis, also called atypical decubital fibroplasia, was recently described as a distinctive fibroblastic proliferation occurring predominantly in elderly, bed-ridden individuals. This entity can easily be misdiagnosed as a malignant process. CASE: A 70-year-old, white male presented with an enlarging right hip mass. Fine needle aspiration yielded spindled and ovoid cells with ample cytoplasm and occasional nuclear atypia. The histologic features of a subsequent biopsy and resection specimen included a zonal pattern of fibrinoid necrosis with surrounding reactive fibroblasts, histiocytes and vascular proliferation, which are characteristic of ischemic fasciitis. CONCLUSION: Ischemic fasciitis can be mistaken clinically, cytologically and histologically for sarcoma. The cytologic findings seen in this case, when combined with the clinical history, were sufficient to avoid misdiagnosis of malignancy in a benign, proliferative lesion.     

Synthesis and antimycobacterial activity of nitroxanthones. 2nd communication: antimycobacterial activity

Prevention of intraoperative blood loss during liver resection is of prime concern. Intraoperative blood loss has indeed repeatedly been shown to adversely influence the short-term prognosis of patients undergoing liver resection. There is in addition evidence that it could be associated with an increased risk; of recurrence in patients operated for an hepato-biliary malignancy through impairment of the patient's immune response. The prime concern of the hepato-biliary surgeon is to minimize blood loss through the control of the major vascular structures this may be achieved in several ways that range from segmental portal control to total hepatic vascular occlusion. The type of vascular occlusion should be selected according to the indication and in particular location of the tumour and presence of an associated underlying liver disease, the patient's cardiovascular status and the experience of the operator. Aim of the authors is to describe the various types of vascular control as well as their benefits and drawbacks so as to use the most appropriate technique according, to each patient' requirements.     

Inhibition of anaerobic phosphate release by nitric oxide in activated sludge

Activated sludge not containing significant numbers of denitrifying, polyphosphate [poly(P)]-accumulating bacteria was grown in a fill-and-draw system and exposed to alternating anaerobic and aerobic periods. During the aerobic period, poly(P) accumulated up to 100 mg of P x g of (dry) weight. When portions of the sludge were incubated anaerobically in the presence of acetate, 80 to 90% of the intracellular poly(P) was degraded and released as orthophosphate. Degradation of poly(P) was mainly catalyzed by the concerted action of polyphosphate:AMP phosphotransferase and adenylate kinase, resulting in ATP formation. In the presence of 0.3 mM nitric oxide (NO) in the liquid-phase release of phosphate, uptake of acetate, formation of poly-beta-hydroxybutyrate, utilization of glycogen, and formation of ATP were severely inhibited or completely abolished. In cell extracts of the sludge, adenylate kinase activity was completely inhibited by 0.15 mM NO. The nature of this inhibition was probably noncompetitive, similar to that with hog adenylate kinase. Activated sludge polyphosphate glucokinase was also completely inhibited by 0.15 mM NO. It is concluded that the inhibitory effect of NO on acetate-mediated phosphate release by the sludge used in this study is due to the inhibition of adenylate kinase in the phosphate-releasing organisms. The inhibitory effect of nitrate and nitrite on phosphate release is probably due to their conversion to NO. The lack of any inhibitory effect of NO on adenylate kinase of the poly(P)-accumulating Acinetobacter johnsonii 210A suggests that this type of organism is not involved in the enhanced biological phosphate removal by the sludges used.     

Natural history of postterm choriocarcinoma

Insulin-like growth factor-I (IGF-I) effects on chicken growth and development are poorly understood. This study examined the effect of IGF-I on protein synthesis rates in various tissues in the male broiler chicken. At three weeks of age, osmotic minipumps were subcutaneously implanted in the scapular area. Chickens were infused with either chicken IGF-I (450 micrograms/kg BW/day) or saline. After treatment for 5 days, the chickens received a flooding dose of [3H]-phenylalanine, and were sacrificed 20 min later. Wing vein blood samples were taken at 0, 5, 10 and 20 min post-injection. The following tissues were removed and frozen for analysis: pectoralis muscle, gastrocnemius muscle, heart, liver, and small intestine. In vivo total protein synthesis measurements were made using the double-label technique. Contractile protein degradation was evaluated using intracellular free 3-methylhistidine concentrations in skeletal muscle. There were no significant differences in absolute or relative body growth rates over the treatment period. Skeletal muscle (pectoralis and gastrocnemius) weights were significantly decreased with IGF-I treatment, while heart weight was significantly increased. Plasma insulin levels were significantly lower in IGF-treated chickens compared to that in control birds. There was no effect of IGF-I on protein synthesis rates in any of the tissues examined. Intracellular free 3-methylhistidine concentrations were higher in both the gastrocnemius (17%) and pectoralis muscles (25%) of chickens treated with IGF-I. This data demonstrates that IGF-I may have an indirect effect to regulate muscle protein turnover rates.     

Artificial neural networks and logistic regression as tools for prediction of survival in patients with Stages I and II non-small cell lung cancer

BACKGROUND: This study examines the role of participation in psychosocial treatment as a mediator of the clinical effectiveness of clozapine. METHODS: Subjects participated in a 12-month double-blind random-assignment trial comparing clozapine and haloperidol in patients hospitalized 30 to 364 days for refractory schizophrenia at 15 Department of Veterans Affairs medical centers. A broker-advocate case management intervention was used to facilitate participation in psychosocial treatments and to document such participation. RESULTS: Between those who continued receiving clozapine (n=122) or a conventional antipsychotic drug (n=169) for 12 months, those receiving clozapine were more likely to participate in psychosocial rehabilitation treatment. Although they were no more likely to receive clinical recommendations for such treatments, they were more likely to both verbally accept recommendations and to act on them. Structural equation modeling shows that participation in psychosocial treatment did not play a mediating role in clozapine's effect on outcomes at 6 months, but was associated with both reduced symptoms and improved quality of life at 12 months. CONCLUSIONS: Clozapine facilitates participation in psychosocial treatment, and such enhanced participation is associated with improved quality-of-life and symptom outcomes. Psychosocial rehabilitation should be offered concomitantly with clozapine.     

Vascular endothelial growth factor is essential for corpus luteum angiogenesis

OBJECTIVE: To compare within-subject variability of plasma glucose measured 2 h after a glucose tolerance test (GTT) with that of plasma glucose measured 2 h after administration of a standardized test meal (diabetes screening product [DSP], Ceapro, Edmonton, Alberta, Canada) and to determine the relationship between the two sets of plasma glucose measurements. RESEARCH DESIGN AND METHODS: Plasma glucose and insulin responses of 36 overnight-fasted subjects (10 lean normal, 9 obese normal, 9 with impaired glucose tolerance [IGT], and 8 with mild diabetes) were studied on eight different mornings after they consumed 75 g oral glucose or 50 g carbohydrate from the DSP. Each test meal was repeated four times by each subject. Within-subject coefficients of variation (CVs) (CV = 100 x SD/mean) of plasma glucose concentrations 2 h after administration of the GTT and DSP were compared by repeated measures ANOVA and linear regression analysis. RESULTS: Mean plasma glucose 2 h after administration of the DSP (D) was linearly related to that 2 h after the GTT (G): G = 1.5 x D - 1.6 (r = 0.97, P < 0.0001). The CV of 2-h plasma glucose was significantly lower after administration of the DSP, 10.5 +/- 1.0%, than after the GTT, 12.7 +/- 1.18% (P = 0.025). The effect of test meal on CV differed in different groups of subjects (P = 0.018), with the largest difference found in IGT subjects, in whom the CV after DSP administration was 47% less than after the GTT (P = 0.0005). The DSP was significantly more palatable and produced fewer adverse symptoms than the GTT. CONCLUSIONS: Plasma glucose concentrations measured 2 h after DSP administration are closely related to those measured 2 h after the GTT but are more consistent than the 2-h post-GTT concentrations within the critical IGT range. This finding suggests that measurement of plasma glucose 2 h after administration of the DSP may allow more precise discrimination among normal glucose levels, IGT, and diabetes than measurement of plasma glucose 2 h after the GTT.     

Skeletal cell stresses and bone adaptation

BACKGROUND: We have previously shown that growth hormone (GH) consistently stimulates proliferation of human osteoblasts in vitro. In rat osteoblasts, GH augments the effects of insulin-like growth factor (IGF) I on cell proliferation and differentiation. We therefore investigated the effects of IGF-I and -II alone and in combination with GH on human osteoblasts in vitro. METHODS: Human osteoblast-like cells (HOB) were established from trabecular explants (n = 18) and human marrow stromal cells (HMS) from marrow aspiration (n = 21). The cell cultures were stimulated with IGF-I or IGF-II (1, 10 or 100 ng mL-1) alone, in combination with hGH (100 ng mL-1) or after prestimulation with hGH. RESULTS: IGF-I alone, in combination with hGH and after pretreatment with hGH, increased proliferation of HOB and HMS by 49-190% (P < 0.05-0.01). IGF-II alone, in combination with hGH and after pretreatment with hGH increased proliferation of HOB by 57-158% (P < 0.01). In HMS only IGF-II in combination with hGH and after prestimulation with hGH increased proliferation. IGF-I alone and in combination with hGH decreased alkaline phosphatase (AP) in both cell types. IGF-II did not affect AP in HOB, but increased AP in HMS, this effect was abolished by hGH. In HOB, collagen production (PICP) was increased by IGF-II but unaffected by IGF-I. In HMS, PICP was decreased by IGF-I and -II but increased by hGH. Co-stimulation further increased PICP. CONCLUSION: IGF-I and -II exerted proliferative effects on both HOB and HMS. Co-stimulation with GH exhibited synergism in enhancing the proliferative response. In HMS prestimulation improved the proliferative response significantly. The effects of the IGFs on differentiation are more complex and dependent on cell maturation and of the IGF used.