Imaging lesions of the cavernous sinus

Our aim was to review the imaging findings of relatively common lesions involving the cavernous sinus (CS), such as neoplastic, inflammatory, and vascular ones. The most common are neurogenic tumors and cavernoma. Tumors of the nasopharynx, skull base, and sphenoid sinus may extend to the CS as can perineural and hematogenous metastases. Inflammatory, infective, and granulomatous lesions show linear or nodular enhancement of the meninges of the CS but often have nonspecific MR imaging features. In many of these cases, involvement elsewhere suggests the diagnosis. MR imaging is sensitive for detecting vascular lesions such as carotid cavernous fistulas, aneurysms, and thromboses.

Is soft drink consumption associated with body composition? A cross-sectional study in Spanish adolescents

OBJECTIVES

Published data about the association between the consumption of sweetened soft-drinks (SSD) and obesity in childhood are controversial and still inconsistent. In addition, data are lacking in the Spanish population. The purpose of this study was therefore, to explore the cross-sectional association between body composition-related parameters and SSD consumption in Spanish adolescents.

SUBJECTS AND METHODS

A representative sample of 1,523 adolescents (768 boys and 755 girls), with complete dietary data as well as anthropometric measurements, were included in this study. Weight, height, waist circumferences, and 6 skinfolds were measured, and BMI and percentage body fat were calculated. From a 24h dietary recall the subjects were grouped in 3 groups according to their SSD consumption: 1) Non-consumers (0 g of SSD consumption); 2) Moderate consumption (< 336 g/day of SSD, equivalent to the average SSD portion size); and 3) High consumption (> 336 g/day of SSD).

RESULTS

67% males and 75% females did not consume any SSD the day before the dietary recall interview. Males consumed more SSD than females. Regarding the association between SSD consumption and measures of obesity, no difference was observed between the three groups of SSD consumption in any of the anthropometric measurement, BMI or body fat.

CONCLUSION

As no association was present between SSD consumption and obesity in our cross-sectional study we suggest that dietary patterns and habits as well as lifestyle factors such as physical activity should be present when examining cross-sectional or longitudinal relationships with obesity. Multidisciplinary intervention studies are crucial when trying to develop solutions against the increasing obesity epidemic.

CT and MR imaging of progressive dural involvement by nephrogenic systemic fibrosis

We present a patient with progressive dural calcifications, thickening, and enhancement presumably related to the development of nephrogenic systemic fibrosis (NSF). Head CT demonstrated progressive dural calcifications, whereas MR imaging demonstrated progressive dural thickening and enhancement during a 3-year period in which the patient received several gadolinium-enhanced MR imaging studies. To the best of our knowledge, dural calcifications are the only described intracranial finding of NSF.

Differentiation between classic and atypical meningiomas with use of diffusion tensor imaging

BACKGROUND AND PURPOSE

The differentiation between classic and atypical meningiomas may have implications in preoperative planning but may not be possible on the basis of conventional MR imaging. Our hypothesis was that classic and atypical meningiomas have different patterns of intratumoral water diffusion that will allow for differentiation between them.

MATERIALS AND METHODS

Preoperative diffusion tensor imaging (DTI) was performed in 12 classic and 12 atypical meningiomas. Signal intensity of solid-enhancing tumor regions on diffusion-weighted trace images and apparent diffusion coefficient (ADC) and fractional anisotropy (FA) maps was assessed. Regions of interest (ROIs) were placed in solid-enhancing regions, peritumoral edema, and contralateral normal-appearing white matter (NAWM) to measure tensor metrics including major (lambda(1)), intermediate (lambda(2)) and minor eigenvalues (lambda(3)) and FA and ADC values. Distribution of tensor shapes within enhancing tumors was calculated for all tumors. Differences between classic and atypical meningiomas in tumor signal intensity, intratumoral and peritumoral tensor metrics, as well as tensor shapes distribution were statistically analyzed.

RESULTS

A significantly greater proportion of atypical meningiomas were isointense and hypointense on ADC maps (P = .007). Classic meningiomas had significantly lower FA (P = .012), higher ADC (P = .011), greater lambda(2) (P = .020) and lambda(3) (P = .003). There was significantly more spherical diffusion in classic than in atypical meningiomas (P = .020). All diffusion tensor metrics for peritumoral edema of the 2 tumor groups did not differ.

CONCLUSION

DTI showed that intratumoral microscopic water motion is less organized in classic than in atypical meningiomas. This feature may allow for noninvasive differentiation between classic and atypical meningiomas.

Technological Characterization of Experimental Natural Rennets Pastes

Four types of lamb rennet pastes were characterized according to the sort of abomasa and the treatment it received: full fresh abomasa (FFA), full dried abomasa (FDA), empty dried abomasa (EDA), and empty frozen abomasa (EFA). These rennet pastes were studied by means of different technological parameters (milk clotting time, chymosin content, lipase activity, and aptitude against milk coagulation).The highest level of clotting activity (391.20 IMCU/g) corresponded to the rennet EDA whereas the lowest (172.87IMCU/g) was found in EFA. The chymosin content of the pastes classified them as rennet extracts, the highest chymosin level (80.46%) being found in the paste from FDA and the lowest (71.10%) being obtained from FFA.The highest level of lipase activity (10.57 U/g) was found in EDA whereas the lowest (1.46 U/g) was in paste FDA. Milk coagulation aptitude was studied through the use of a near infra-red radiation dispersion sensor. The highest value of Rmax (0.049 min-1) found in the rennet paste made with EDA indicated a higher level of casein hydrolysis and greater aggregation speed. For the same rennet at tmax value of 6.1 min was established lower than for other rennet preparations which reflected the fact that this rennet hydrolyzed 80% of the K-casein in a shorter period of time. It is concluded that the best natural lamb rennet paste of this work was FFA due to it combines appropriate proteolytic and lipolytic activities although it does not reach the maximum values for each technological parameters analyzed.

Pilomyxoid astrocytoma: expanding the imaging spectrum

BACKGROUND AND PURPOSE

Pilomyxoid astrocytoma (PMA) is a recently described variant of pilocytic astrocytoma (PA) with unique clinical and histopathologic characteristics. Because the histopathology of PMA is distinct from that of PA, we hypothesized that PMAs would display distinctive imaging characteristics. We retrospectively reviewed the imaging findings in a large number of patients with PMA to identify these characteristics.

MATERIALS AND METHODS

CT and MR images, pathology reports, and clinical information from 21 patients with pathology-confirmed PMA from 7 institutions were retrospectively reviewed. CT and MR imaging findings, including location, size, signal intensity, hemorrhage, and enhancement pattern, were tabulated.

RESULTS

Patients ranged in age from 9 months to 46 years at initial diagnosis. Sex ratio was 12:9 (M/F). Twelve of 21 (57%) tumors were located in the hypothalamic/chiasmatic/third ventricular region. Nine (43%) occurred in other locations, including the parietal lobe (2/21), temporal lobe (2/21), cerebellum (2/21), basal ganglia (2/21), and fourth ventricle (1/21). Ten (48%) tumors showed heterogeneous rim enhancement, 9 (43%) showed uniform enhancement, and 2 (9%) showed no enhancement. Five (24%) masses demonstrated intratumoral hemorrhage.

CONCLUSION

This series expands the clinical and imaging spectrum of PMA and identifies characteristics that should suggest consideration of this uncommon diagnosis. One third of patients were older children and adults. Almost half of all tumors were located outside the typical hypothalamic/chiasmatic region. Intratumoral hemorrhage occurred in one quarter of patients. PMA remains a histologic diagnosis without definitive imaging findings that distinguish it from PA.

Primary cerebral lymphoma and glioblastoma multiforme: differences in diffusion characteristics evaluated with diffusion tensor imaging

BACKGROUND AND PURPOSE

Differentiating between primary cerebral lymphoma and glioblastoma multiforme (GBM) based on conventional MR imaging sequences may be impossible. Our hypothesis was that there are significant differences in fractional anisotropy (FA) and apparent diffusion coefficient (ADC) between lymphoma and GBM, which will allow for differentiation between them.

MATERIALS AND METHODS

Preoperative diffusion tensor imaging (DTI) was performed in 10 patients with lymphoma and 10 patients with GBM. Regions of interest were placed in only solid-enhancing tumor areas and the contralateral normal-appearing white matter (NAWM) to measure the FA and ADC values. The differences in FA and ADC between lymphoma and GBM, as well as between solid-enhancing areas of each tumor type and contralateral NAWM, were analyzed statistically. Cutoff values of FA, FA ratio, ADC, and ADC ratio for distinguishing lymphomas from GBMs were determined by receiver operating characteristic curve analysis.

RESULTS

FA and ADC values of lymphoma were significantly decreased compared with NAWM. Mean FA, FA ratio, ADC (x10(-3) mm(2)/s), and ADC ratios were 0.140 +/- 0.024, 0.25 +/- 0.04, 0.630 +/- 0.155, and 0.83 +/- 0.14 for lymphoma, respectively, and 0.229 +/- 0.069, 0.40 +/- 0.12, 0.963 +/- 0.119, and 1.26 +/- 0.13 for GBM, respectively. All of the values were significantly different between lymphomas and GBM. Cutoff values to differentiate lymphomas from GBM were 0.192 for FA, 0.33 for FA ratio, 0.818 for ADC, and 1.06 for ADC ratio.

CONCLUSIONS

The FA and ADC of primary cerebral lymphoma were significantly lower than those of GBM. DTI is able to differentiate lymphomas from GBM.

The response of gastrointestinal microbiota to avilamycin, butyrate, and plant extracts in early-weaned pigs

An experiment was designed to evaluate the effects of 3 different additives on the gastrointestinal microbiota of early-weaned pigs. Early-weaned (18 to 22 d; n = 32) pigs (6.0 +/- 0.10 kg of BW) from 8 litters were randomly distributed into 8 pens. Each pen was assigned 1 of 4 dietary treatments: a prestarter or control diet, the control diet with 0.04% avilamycin (AB), with 0.3% sodium butyrate, or with 0.03% plant extract mixture (XT; standardized mixture with 5% (wt/wt) carvacrol extracted from Origanum spp., 3% cinnamaldehyde extracted from Cinnamonum spp., and 2% capsicum oleoresin from Capsicum annum). At the end of the experimental period, 8 pigs per treatment were killed, and samples of their intestinal content were taken. The total bacterial load along the gastrointestinal tract (GIT; stomach, jejunum, cecum, and distal colon) and the lactobacilli and enterobacteria in the jejunum and cecum were measured by quantitative PCR. The total microbial counts along the GIT did not differ among the diets, but there was an increase in the lactobacilli:enterobacteria ratio in the cecum of the piglets on the XT diet (P = 0.003). Restriction fragment length polymorphism of the PCR-amplified V3, V4, and V5 regions of the 16S rDNA gene showed changes in the structure of the microbial community in the jejunum. Dendrograms grouped animals by diets; control with 0.3% sodium butyrate was the treatment that promoted the biggest changes in the microbial ecosystem, followed by AB and then XT. Biodiversity increased when using additives compared with the control diet (P = 0.002). Microbial metabolic activity along the hindgut was studied using the concentration of purine bases and carbohydrase activities. Different patterns for purine bases were observed between diets (diet x intestinal section, P = 0.01). The control diet reached a maximum purine base concentration at the end of the colon, whereas that of the AB diet was reached at the cecum. We could not detect any cellulase or xylanase activities in animals of this age. Appreciable amylase and amylopectinase activities were found, but they did not differ between diets. The results suggest that the effects of avilamycin, butyrate, or the plant extract would not be related to a reduction in the number of total bacteria inhabiting different sections of the GIT but rather to changes in the ecological structure and metabolic activity of the microbial community.

Use of mannanoligosaccharides and zinc chelate as growth promoters and diarrhea preventative in weaning pigs: Effects on microbiota and gut function1

The efficacy of a commercial source of mannanoligosacharides (BM), organic zinc (BP), or their combination to enhance performance, gastrointestinal health, and immune response in weaned pigs was evaluated. A total of 128 piglets, weaned at 20 +/- 2 d, were housed in 32 pens. Animals received 1 of 4 dietary treatments: a control diet (CT) to which 0.2% of BM, 80 mg/kg of Zn as BP, or both additives (BMP) were added. The experiment lasted for 5 wk including a prestarter period of 2 wk and a starter period of 3 wk. Body weight was recorded and daily feed intake was calculated. Fecal consistency was monitored for the first 21 d. After 2 wk, 32 animals were killed, digesta samples from the stomach, ileum, and cecum were collected, and pH and the short-chain fatty acid profile were determined. Microbiological counts for enterobacteria and lactobacilli were evaluated using quantitative PCR. Histological parameters in the jejunum and immunoglobulin concentrations in serum and ileal digesta were also measured. Both additives improved G:F during the starter period (0.63, 0.69, 0.67, and 0.68 for CT, BM, BP, and BMP, respectively; P < 0.04). Mean fecal score values for the first 21 d were improved by BM and BP, showing decreased values compared with the CT diet (1.22, 0.89, 0.87, and 1.06 for CT, BM, BP, and BMP, respectively; P = 0.002). The addition of BM decreased enterobacteria counts in the jejunum (9.13, 8.05, 8.87, and 7.89 log 16S rRNA gene copies/g of matter for CT, BM, BP, and BMP, respectively; P = 0.05). Empty ileal weight, defined as the segment including the continuous Peyer's patch, tended (P = 0.08) to increase with BP treatment (8.9, 9.6, 11.9, and 10.3 g/kg of BW for CT, BM, BP, and BMP, respectively). Crypt depths in the jejunum were lower in animals fed the combination of the additives (BPM) compared with those fed the control diet (281 vs. 235; P < 0.03). No significant differences were registered in pH, short-chain fatty acids, or serum and ileal immunoglobulin concentrations. The results suggest that the use of BM or BP can improve the efficiency of gain during the starter period.

Posterior fossa dermoid cysts in association with Klippel-Feil syndrome: report of three cases

Although the association of spinal lumbosacral dysraphism and congenital spinal dermoid tumors is well known, the association of craniocervical spinal anomalies and posterior fossa dermoids has only been recognized recently. Advances in imaging technology and awareness of the association likely contribute to an increase in recently reported cases.

Effect of Cutting Time, Temperature, and Calcium on Curd Moisture, Whey Fat Losses, and Curd Yield by Response Surface Methodology

Response surface methodology was used to study the effect of temperature, cutting time, and calcium chloride addition level on curd moisture content, whey fat losses, and curd yield. Coagulation and syneresis were continuously monitored using 2 optical sensors detecting light backscatter. The effect of the factors on the sensors' response was also examined. Retention of fat during cheese making was found to be a function of cutting time and temperature, whereas curd yield was found to be a function of those 2 factors and the level of calcium chloride addition. The main effect of temperature on curd moisture was to increase the rate at which whey was expelled. Temperature and calcium chloride addition level were also found to affect the light backscatter profile during coagulation whereas the light backscatter profile during syneresis was a function of temperature and cutting time. The results of this study suggest that there is an optimum firmness at which the gel should be cut to achieve maximum retention of fat and an optimum curd moisture content to maximize product yield and quality. It was determined that to maximize curd yield and quality, it is necessary to maximize firmness while avoiding rapid coarsening of the gel network and microsyneresis. These results could contribute to the optimization of the cheese-making process.

Computer Vision and Color Measurement Techniques for Inline Monitoring of Cheese Curd Syneresis

Optical characteristics of stirred curd were simultaneously monitored during syneresis in a 10-L cheese vat using computer vision and colorimetric measurements. Curd syneresis kinetic conditions were varied using 2 levels of milk pH (6.0 and 6.5) and 2 agitation speeds (12.1 and 27.2 rpm). Measured optical parameters were compared with gravimetric measurements of syneresis, taken simultaneously. The results showed that computer vision and colorimeter measurements have potential for monitoring syneresis. The 2 different phases, curd and whey, were distinguished by means of color differences. As syneresis progressed, the backscattered light became increasingly yellow in hue for circa 20 min for the higher stirring speed and circa 30 min for the lower stirring speed. Syneresis-related gravimetric measurements of importance to cheese making (e.g., curd moisture content, total solids in whey, and yield of whey) correlated significantly with computer vision and colorimetric measurements.

Utility of navigator-prospective acquisition correction technique (PACE) for reducing motion in brain MR imaging studies

In this retrospective review, we demonstrate the utility of using a commercially available gated navigator sequence (prospective acquisition correction technique [PACE]) to reduce rhythmic breathing motion on brain MR images. For purposes of this report, we studied 2 sedated patients who had marked head rocking, one due to deep breathing and snoring and the other due to ventilator support. Motion degraded the routine images, which, despite a short acquisition time, were nondiagnostic. After application of PACE, a technique commonly used in abdominal studies, the brain images in both patients were judged to be of acceptable diagnostic quality. The use of PACE to diminish head motion is now routine at our institution when sedated or ventilated patients degrade images with involuntary head rocking.

Scarce influence of corticosteroid boluses on long-term viral load and liver histology in transplanted patients with recurrent hepatitis C

Corticosteroid boluses, which are the treatment for acute rejection episodes, have been shown to produce transient increases in viremia. However, their effect on long-term viral load, histological activity index (HAI), and fibrosis has not been well established. The aim of our study was to compare late viral load, HAI, and fibrosis in patients with versus without steroid boluses in the immediate posttransplant period. We analyzed patients transplanted due to hepatitis C virus. Inclusion criteria were: no change in immunosuppression (cyclosporine or tacrolimus with/without mycophenolate); no steroids in the previous 4 months; no antiviral treatment; liver biopsy and viral load determination >12 months after transplantation. Exclusion criteria were HIV, hepatitis B, and active cytomegalovirus infection. Nonparametric tests were used to compare viral load, HAI, and fibrosis (Ishak-score) among patients who received steroid boluses for an acute rejection episode (group 1) versus those who did not (group 2). Among the 48 selected patients were 38 men with the overall mean age of the entire group of 55.6 +/- 10.9 years. The mean period from liver transplantation was 53.25 +/- 33.4 months. Thirty-four (70.1%) were treated with tacrolimus and the rest, cyclosporine. Eleven (22.9%) had and 37 (77.1%) had not received corticosteroid boluses. The viral load was similar in groups 1 and 2 (5.74 +/- 0.54 vs 5.98 +/- 0.53 Log(10) IU per mL, P = .32). Fibrosis was also similar (2.5 +/- 1.6 vs 2.2 +/- 1.7, P = .56). However, HAI was higher in group 1 (7.5 +/- 1.7 vs 6.0 +/- 1.7, P = .026). In conclusion, although long-term viral load was similar in patients who had versus had not received one cycle of steroid boluses, the HAI was significantly higher in the former cohort, but had not resulted in greater fibrosis during the study follow-up.

Hepatitis C Virus Recurrence After Liver Transplantation: Influence of Immunosuppressive Regimens on Viral Load and Liver Histology

Cyclosporine has recently been reported to produce in vitro suppression of hepatitis C virus replication driven by blockade of cyclophilins, an effect not shown for tacrolimus. However, the clinical consequence of this in vitro finding have not been well studied in vivo. We compared viral load and fibrosis in transplanted patients receiving monotherapy with tacrolimus or cyclosporine. Patients with recurrent hepatitis C after transplantation were selected from two tertiary centers with the following inclusion criteria: monotherapy with tacrolimus or cyclosporine for more than 12 months before viral load measurement, no antiviral treatment, corticosteroids stopped within 12 months after transplantation. HIV, hepatitis B, and active infection by cytomegalovirus were excluded. Patient characteristics, viral load, and fibrosis were compared by univariate analysis between the cyclosporine and tacrolimus groups. Significant variables, viral load, and fibrosis were included in a multivariate model. Sixty-six patients were included, 46 on tacrolimus and 20 on cyclosporine. Fifty-six were male, and the mean age was 55.3 +/- 10.1 years. Fibrosis (Ishak score) was 3.9 +/- 1.9 in the cyclosporine group and 2.7 +/- 1.9 in the tacrolimus group (P = .019). Viral load (log(10)IU/mL) was 5.8 +/- 0.5 and 5.9 +/- 0.5, respectively (P = .7) and time since liver transplantation was 95.3 +/- 47.7 and 41.1 +/- 16.8 months (P = .0001). In the multivariate model, viral load (P = .65) and fibrosis (P = .24) were not significantly different and only time since transplantation remained significant (P = .0001). In conclusion, viral load was not different in patients with tacrolimus as compared with cyclosporine, and the lower fibrosis observed in the cyclosporine group lacked significance when considered together with time since liver transplantation.

Postnatal developmental changes in CO2 sensitivity in rats

Ventilatory sensitivity to CO2 in awake adult Brown Norway (BN) rats is 50–75% lower than in adult Sprague-Dawley (SD) and salt-sensitive Dahl S (SS) rats. The purpose of the present study was to test the hypothesis that this difference would be apparent during the development of CO2 sensitivity. Four litters of each strain were divided into four groups such that rats were exposed to 7% inspired CO2 for 5 min in a plethysmograph every third day from postnatal day (P) 0 to P21 and again on P29 and P30. From P0 to P14, CO2 exposure increased pulmonary ventilation (V̇e) by 25–50% in the BN and SD strains and between 25 to over 200% in the SS strain. In all strains beginning around P15, the response to CO2 increased progressively reaching a peak at P19–21 when V̇e during hypercapnia was 175–225% above eucapnia. There were minimal changes in CO2 sensitivity between P21 and P30, and at both ages there were minimal between-strain differences. At P30, the response to CO2 in the SS and SD strains was near the adult response, but the response in the BN rats was 100% greater at P30 than in adults. We conclude that 1) CO2-sensing mechanisms, and/or mechanisms downstream from the chemoreceptors, change dramatically at the age in rats when other physiological systems are also maturing (∼P15), and 2) there is a high degree of age-dependent plasticity in CO2 sensitivity in rats, which differs between strains.

Effects of butyrate, avilamycin, and a plant extract combination on the intestinal equilibrium of early-weaned pigs1

We evaluated the effects of 3 additives, sodium butyrate (AC), avilamycin (AB), and a combination of plant extracts (XT), on the productive performance and the intestinal environment of the early-weaned pig. The XT was a standardized mixture with 5% (wt/wt) carvacrol (from Origanum spp.), 3% cinnamaldehyde (from Cinnamonum spp.), and 2% capsicum oleoresin (from Capsicum annum). Pigs (n = 32) weaned at 18 to 22 d of age with an initial BW of 6.0 +/- 0.10 kg were allocated to 8 pens that, in turn, were allocated to 4 treatments. The treatments included a basal diet (CT) or the basal diet supplemented with 0.3% of AC, 0.04% of AB, or 0.03% of XT. Productive performance was determined during the initial 14 d postweaning. On d 19 and 21 of the experiment, the pigs were killed to allow collection of digesta and intestinal tissue to evaluate variables indicative of aspects of the gastrointestinal environment. Treatments AB and AC improved G:F (P = 0.012 and 0.003, respectively) compared with the CT. Butyrate included in the diet was only detected in the stomach but not in cranial jejunum. When compared with CT, AC produced a lower ileal starch digestibility (P = 0.002) and a lower whole-tract OM and starch digestibility (P = 0.001 and 0.003, respectively), related to a lower VFA concentration in the cranial colon (P = 0.082) and a numerically reduced branched VFA percentage in the rectum. The AB treatment diminished propionate production in caudal colon (P = 0.002) and rectum (P = 0.012) compared with CT. The AC group exhibited deeper crypt depth in the jejunum without variations in villus height compared with CT (P = 0.042). The AC and AB groups also increased goblet cell presence in the colon (P = 0.001 and 0.032, respectively). On the other hand, AB and XT diminished intraepithelial lymphocytes in the jejunum (P = 0.003 and 0.034, respectively). The XT increased lymphocyte presence in the colon (P = 0.003). These results show the important influence of AB and AC on productive performance and on pig gut dynamics. The intestinal modifications observed for AB and AC compared with CT suggest distinct modes of action for each additive.

Nutritional control, gene regulation, and transformation of vascular smooth muscle cells in atherosclerosis

Contractile-state smooth muscle cells (SMC), the only cell type in the arterial media, undergoes migration to the intima, proliferation, and abundant extracellular matrix production during the early stages of atherosclerosis. This involves the ingestion of low-density lipoprotein (LDL) and modified or oxidised LDL by macrophages together with SMC by several pathways including a scavenger pathway leading to accumulation of cholesterol esters and formation of foam cells. High-plasma cholesterol levels constitute a major causative risk for atherosclerosis. The membrane-bound transcription factor called sterol regulatory element binding protein (SREBP) activates gene-encoding enzymes of cholesterol and fatty acid biosynthesis. The SREBP expression, in response to diet, shows that are involved in both lipogenesis and cholesterol homeostasis, moreover SREBPs are regulated directly by cholesterol. Animal models were used in trials of atherosclerosis, and cholesterol feeding has been described elsewhere as producing atherosclerotic lesions. We have examined the morphological, molecular and proliferative change in arterial SMC mimicking such a cholesterol diet, this transformed SMC is a good model to study the alterations of the differentiated state of SMC, and the transformation into foam cell, caused by cholesterol-rich diet. Despite the complexity of the interactions in atherosclerosis, there are many opportunities to affect the homeostatic balance of the artery wall at SMC levels. We have considered here some of the possible targets for intervention with promising strategies for the nutritional control of the genes, and, in a general way, the possibilities for modulating the expression of genes influencing atherosclerosis.

Apparent diffusion coefficients for differentiation of cerebellar tumors in children

BACKGROUND AND PURPOSE

Diffusion-weighted imaging (DWI) and apparent diffusion coefficient (ADC) maps provide information at MR imaging that may reflect cell attenuation and integrity. We hypothesized that cerebellar tumors in children can be differentiated by their ADC values.

METHODS

Brain MR imaging studies that included ADC maps were retrospectively reviewed in 32 patients with histologically proved cerebellar neoplasm. There were 17 juvenile pilocytic astrocytomas (JPA), 8 medulloblastomas, 5 ependymomas, and 2 rhabdoid (atypical teratoid/rhabdoid tumor [AT/RT]) tumors. Absolute ADC values of contrast-enhancing solid tumor regions and ADC ratios (ADC of solid tumor to ADC of normal-appearing white matter) were compared with the histologic diagnosis. ADC values and ratios of JPAs, medulloblastomas, and ependymomas were compared by using a 2-tailed t test and one-way analysis of variance (ANOVA).

RESULTS

ADC values were significantly higher in pilocytic astrocytomas (1.65 +/- 0.27) (mean +/- SD) than in ependymomas (1.10 +/- 0.11) (P = .0003) and medulloblastomas (0.66 +/- 0.15) (P < .0001). Ependymomas demonstrated significantly higher ADC values than medulloblastomas (P = .0005). The observed differences were statistically significant on ANOVA (P < .001). ADC ratios were also significantly different among these 3 tumor types. AT/RT ADC values were similar to medulloblastoma. The range of ADC values and ratios within JPAs and ependymomas did not overlap with that of medulloblastomas.

CONCLUSION

Assessment of ADC values of enhancing solid tumor is a simple and reliable technique for preoperative differentiation of cerebellar tumors in pediatric patients. Our cutoff values of >1.4 x 10(3) mm(2)/s for JPA and <0.9 x 10(3) mm(2)/s for medulloblastoma were 100% specific.

Low-Pressure DC Air Plasmas. Investigation of Neutral and Ion Chemistry

The neutral and charged species present in a direct current (dc) hollow cathode, gas flow, air reactor are experimentally studied by quadrupole mass spectrometry. The degree of ionization of the plasma and the electron mean temperature with decreasing air pressure, for constant discharge current, are measured with a double Langmuir probe. The chemical composition of the plasma changes appreciably over the 3 x 10(-3) to 5 x 10(-2) mbar range investigated: at the lowest pressures studied, O2 dissociation is up to 60% and the concentration of NO is half that of N2; concerning ions, NO+ and N2+ are dominant for the whole pressure range. A kinetic model of the plasma including electrons, neutrals, and positive ions is developed to account for the experimental observations; it is consistent with energy balance and predicts that heterogeneous processes are the main source of NO and that the contribution of ions to the global chemistry of neutrals is of minor significance even for the lowest pressures.