Intracranial circulation: pulse-sequence considerations in three- dimensional (volume) MR angiography

The technique and feasibility of magnetic resonance (MR) angiography of intracranial vessels were studied in 35 healthy volunteers. Variations in image orientation, repetition time (TR), and flip angle were evaluated to determine their effects on flow-related enhancement. Gradient modifications--including echo time (TE), motion compensation, bandwidth, and field of view--were also studied in an effort to reduce motion-induced phase shifts. Results indicated that a FISP (fast imaging with steady precession) sequence with a TR of 50 msec, TE of 15 msec, velocity compensation in the read and section-select directions, acceleration compensation in the read direction, anisotropic volume, and a 1.25-mm partition thickness produced three-dimensional angiographic MR images that were accurate and reproducible in the depiction of the major intracranial vessels. Difficulties with field of view, persistent signal void secondary to higher-order motion, and spatial resolution remain major problems requiring additional study.     

Acute-phase response predicts erythropoietin resistance in hemodialysis and peritoneal dialysis patients

We defined erythropoietin (EPO) resistance by the ratio of the weekly EPO dose to hematocrit (Hct), yielding a continuously distributed variable (EPO/Hct). EPO resistance is usually attributed to iron or vitamin deficiency, hyperparathyroidism, aluminum toxicity, or inflammation. Activation of the acute-phase response, assessed by the level of the acute-phase C-reactive protein (CRP), correlates strongly with hypoalbuminemia and mortality in both hemodialysis (HD) and peritoneal dialysis (PD) patients. In this cross-sectional study of 92 HD and 36 PD patients, we examined the contribution of parathyroid hormone (PTH) levels, iron indices, aluminum levels, nutritional parameters (normalized protein catabolic rate [PCRn]), dialysis adequacy (Kt/V), and CRP to EPO/Hct. Albumin level serves as a measure of both nutrition and inflammation and was used as another independent variable. Serum albumin level (deltaR2 = 0.129; P < 0.001) and age (deltaR2 = 0.040; P = 0.040) were the best predictors of EPO/Hct in HD patients, and serum albumin (deltaR2 = 0.205; P = 0.002) and ferritin levels (deltaR2 = 0.132; P = 0.015) in PD patients. When albumin was excluded from the analysis, the best predictors of EPO/Hct were CRP (deltaR2 = 0.105; P = 0.003) and ferritin levels (deltaR2 = 0.051; P = 0.023) in HD patients and CRP level (deltaR2 = 0.141; P = 0.024) in PD patients. When both albumin and CRP were excluded from analysis in HD patients, low transferrin levels predicted high EPO/Hct (deltaR2 = 0.070; P = 0.011). EPO/Hct was independent of PTH and aluminum levels, PCRn, and Kt/V. High EPO/Hct occurred in the context of high ferritin and low transferrin levels, the pattern expected in the acute-phase response, not in iron deficiency. In well-dialyzed patients who were iron replete, the acute-phase response was the most important predictor of EPO resistance.     

Study of immunohistochemical expression of insulin-like growth factor I and proliferating cell nuclear antigen in thyroid gland papillary carcinoma and its metastasis

BACKGROUND: Several tumor factors are associated with papillary thyroid cancer. Most studies do not compare the expressions of these factors in the primary tumors and in their associated cervical metastasis. METHODS: Paraffin sections of 20 patients with papillary carcinoma of the thyroid gland with lymph node metastasis were studied. The presence and distribution of insulin-like growth factor I (IGF-I) and proliferating cell nuclear antigen (PCNA) was analyzed, through immunohistochemical technique, in both primaries and lymph node metastasis. The results were correlated with clinical-pathologic data (sex, age, size of primary, multicentricity, thyroid capsule invasion, lymphatic and blood vessels invasion, development of distant metastasis, and associated thyroid diseases). RESULTS: The qualitative analysis showed the reaction for IGF-I was present in more than 90% of the neoplastic cells in both primaries and lymph node metastasis. No correlation with the clinical-pathological features was observed. Regarding the PCNA, the mean percentage of nuclei stained showed no statistical difference between primaries and metastasis (p = 0.598). Except for age, clinicopathologic data had no influence on the mean percentage of nuclei stained. A correlation was verified between the percentage of cells stained by PCNA in primary tumors and the patients' age (p < 0. 01). CONCLUSIONS: The expressions of these tumor factors are equally intense for both primary and metastatic tissue in papillary thyroid cancer. Despite the small size of the sample, the expressions of IGF-I and PCNA could not be associated to clinical-pathologic features, except for the age. As patients over 40 years old had higher expression of PCNA, this marker may have prognostic significance for patients with papillary thyroid cancer.     

Remission following an elemental diet or prednisolone in Crohn's disease

The short- and long-term effects of an elemental diet in children with acute Crohn's disease were compared with those of prednisolone in historical controls. Clinical remission was induced in 25 of 30 and in 18 of 28 episodes treated for six weeks with an elemental diet and prednisolone. Patients with proximal disease had longer remission after treatment with an elemental diet (p < 0.05) than did patients with colonic disease after treatment with prednisolone (p < 0.01). Disease activity index score improved in both groups compared with the pretreatment scores (p < 0.05). However, the improvement in the elemental diet group was significantly better than in the prednisolone group (p < 0.001). Changes in linear growth were better after treatment with an elemental diet compared with steroids (p < 0.001). Serum albumin and haematocrit concentrations all improved significantly in the children treated with an elemental diet (p < 0.001) but not in those treated with steroids. Thus an elemental diet was better than prednisolone in proximal disease and confirmed improved growth and nutritional status.     

Essay on the epistemological relationship between probability and scientific method

In the XIX century, regularities in statistics of events were perceived in Medicine and Human Sciences. These regularities raised the possibility of forecasting what considered to be impredictable, and so, probabilistics laws became an alternative to the strictly-causal laws. This work presents a brief historical review of probability calculus and its applications. Some philosophical thoughs, regarding the use of probabilistics models and decision analysis in Medicine, are also discussed.     

Protein serine/threonine phosphatase 2A activity is inhibited by cAMP in MA-10 cells

PP1 and PP2A are members of the protein serine/threonine phosphatases (PPs) family and their activities have been proposed as a requirement for hormone- and cAMP-regulated steroid synthesis. These findings raise the question whether the PPs activity is increased by hormonal action in steroidogenic systems. Thus, the aim of the study was to evaluate the action of cAMP on the activity of PP1 and PP2A in MA-10 Leydig cells. Our results demonstrate that 8Br-cAMP stimulation produces a transient inhibition of PP2A activity. In contrast, PP1 activity remains unchangeable. As reported in other steroidogenic cells, cAMP-induced steroidogenesis in MA-10 cells is reduced by Cantharidin (Can) and also by Calyculin A (CA), two chemically unrelated PP1/PP2A inhibitors (data not shown). Taking into account the inhibitory effect of cAMP treatment on PP2A activity, the latest findings result paradoxical. Therefore, we next evaluated the action of these compounds on total protein synthesis. Can 10(-5) M and CA 10(-7) M markedly reduced total protein synthesis (35 and 50% respectively) in MA-10 cells, measured by 35S-methonine incorporation. These results suggest that hormone-dependent steroidogenesis is working through inhibition of PP2A-dependent dephosphorylation and the effect of PP1/PP2A inhibitors on steroidogenesis may be due to a general inhibition of protein synthesis rather than to a specific action on StAR protein induction.