Hospitalization and hospital mortality rates during the first and second waves of the COVID-19 pandemic in Quebec: interrupted time series and decomposition analysis.

OBJECTIVES: We investigated hospitalization and hospital mortality rates by cause during the first year of the COVID-19 pandemic in Quebec, Canada. STUDY DESIGN: Interrupted time series and decomposition analysis. METHODS: We analyzed hospital mortality during the first (February 25-August 22, 2020) and second waves (August 23, 2020-March 31, 2021), compared with 2019. We identified the cause of death and examined trends using: 1) interrupted time series analysis; 2) log-binomial regression; and 3) decomposition of cause-specific mortality. RESULTS: Hospitalization rates decreased; however, the proportion of deaths increased from 27.0 per 1000 in 2019 to 35.0 per 1000 in the first wave, for an excess of 8.0 deaths per 1000 admissions. COVID-19 was the cause of a third of excess deaths (2.6 per 1000). Other drivers of excess deaths included respiratory conditions (1.6 deaths per 1000), circulatory disorders (0.6 deaths per 1000), and cancer (0.9 deaths per 1000). COVID-19 was the cause of 58% of excess deaths in the second wave. Interrupted time series regression indicated that the proportion of deaths increased at the outset of the first wave but returned to prepandemic levels before increasing again in the second wave. Compared with 2019, the first wave was associated with 1.31 times (95% confidence interval [CI] 1.28-1.33) and the second wave with 1.17 times (95% CI 1.15-1.19) the risk of death during hospitalization. CONCLUSIONS: The pandemic was associated with a greater risk of hospital mortality. Excess deaths were driven by COVID-19 but also other causes, including respiratory conditions, circulatory disorders, and cancer.

Predictors and impact of postoperative atrial fibrillation following thoracic surgery: a state-of-the-art review.

This review of 19 studies (39,783 patients) of atrial fibrillation after thoracic surgery addresses the pathophysiology, incidence, and consequences of atrial fibrillation in this population, as well as its prevention and management. Interestingly, atrial fibrillation was most often identified in patients not previously known to have the disease. Rhythm control with amiodarone was the most commonly used treatment and nearly all patients were discharged in sinus rhythm. Major predictors were age; male sex; history of atrial fibrillation; congestive heart failure; left atrial enlargement; elevated brain natriuretic peptide level; and the invasiveness of procedures. Overall, patients with atrial fibrillation stayed 3 days longer in hospital. We also discuss the importance of standardising research on this subject and provide recommendations that might mitigate the impact postoperative atrial fibrillation on hospital resources.

Obstetric haemorrhage and risk of cardiovascular disease after three decades: a population-based cohort study.

OBJECTIVE: To investigate the association between obstetric haemorrhage and cardiovascular disease up to three decades after pregnancy. DESIGN: Population-based cohort study. SETTING AND POPULATION: All women who delivered between 1989 and 2016 in Quebec, Canada. METHODS: Using hospital admissions data, 1 224 975 women were followed from their first delivery until March 2018. The main exposure measures were antenatal (placenta praevia, placental abruption, peripartum haemorrhage) or postpartum haemorrhage, with or without transfusion. Adjusted Cox regression models were used to assess the association between obstetric haemorrhage and future cardiovascular disease. MAIN OUTCOME MEASURE: Cardiovascular hospitalisation. RESULTS: Among 104 291 (8.5%) women with haemorrhage, 4612 (4.4%) required transfusion. Women with haemorrhage had a higher incidence of cardiovascular hospitalisation than women without haemorrhage (15.5 versus 14.1 per 10 000 person-years; 2437 versus 28 432 events). Risk of cardiovascular hospitalisation was higher for obstetric haemorrhage, with or without transfusion, compared with no haemorrhage (adjusted hazard ratio [aHR] 1.06, 95% CI 1.02-1.10). Women with haemorrhage and transfusion had a substantially greater risk of cardiovascular hospitalisation (aHR 1.47, 95% CI 1.23-1.76). Among transfused women, placental abruption (aHR 1.79, 95% CI 1.06-3.00) and postpartum haemorrhage (aHR 1.38, 95% CI 1.13-1.68) were both associated with risk of cardiovascular hospitalisation. Antenatal haemorrhage with transfusion was associated with 2.46 times the risk of cardiovascular hospitalisation at 5 years (95% CI 1.59-3.80) and 2.14 times the risk at 10 years (95% CI 1.47-3.12). CONCLUSIONS: Obstetric haemorrhage requiring transfusion is associated with maternal cardiovascular disease. The benefit of cardiovascular risk prevention in pregnant women with obstetric haemorrhage requires further investigation. TWEETABLE ABSTRACT: Risk of future cardiovascular disease is increased for women with obstetric haemorrhage who require transfusion.

E-learning and the future of dental education: opinions of administrators and information technology specialists.

The digital revolution and growth of the Internet have led to many innovations in the area of electronic learning (e-learning). To survive and prosper, educators must be prepared to respond creatively to these changes. Administrators and information technology specialists at six dental schools and their parent institutions were interviewed regarding their opinions of the impact that e-learning will have on the future of dental education. Interview questions encompassed vision, rate of change, challenges, role of faculty, resources, enrolment, collaboration, responsibility for course design and content, mission and fate of the institution. The objective of this qualitative study was to sample the opinions of educational administrators and information technology specialists from selected US universities regarding the impact of e-learning on dental education to detect trends in their attitudes. Responses to the survey indicated disagreement between administrators and informational technology specialists regarding the rate of change, generation of resources, impact on enrolment, responsibility for course design and content, mission and fate of the university. General agreement was noted with regard to vision, challenges, role of faculty and need for collaboration.

Use of rat models to mimic alterations in iron homeostasis during human alcohol abuse and cirrhosis.

With alcoholism, there are marked disturbances in iron homeostasis that are linked to alterations in serum transferrin and ferritin concentrations. This study identifies rat models of alcohol abuse that closely mimic these disturbances. Male rats were placed in one of the following three protocols: (1) pair-feeding of liquid diets for 1-8 weeks; (2) agar-block feeding for 8 weeks; or (3) generation of cirrhosis with CCl(4). Serum samples were analyzed for ferritin, transferrin, and iron levels, and the transferrin iron saturation and ferritin/transferrin ratios were calculated. Liver iron concentrations were also determined. Serum transferrin levels were elevated in animals fed alcohol for 8 weeks in pair-feeding and agar-block feeding protocols, but reduced in rats with cirrhosis. Serum ferritin concentration was reduced in rats fed ethanol in the liquid diet, but increased in rats consuming ethanol in agar blocks, in rats pair-fed the liquid control diet, and in rats with cirrhosis. This finding was mirrored by liver nonheme iron concentrations in all experimental groups, but not in the corresponding control groups. Serum iron levels were significantly elevated only in rats fed the liquid control diet. There was a progressive decrease in transferrin iron saturation and ferritin/transferrin ratios for animals fed ethanol in the liquid diet, but not when ethanol was ingested from agar blocks. The development of cirrhosis resulted in elevated liver iron concentrations and doubled ferritin/transferrin ratios. It is concluded that these models may be used to study disturbances in iron homeostasis that occur during alcohol abuse and the (subsequent) development of liver disease.

Measurement of endodontic file lengths: calibrated versus uncalibrated digital images.

This in vitro study compared the accuracy of file length measurements made on calibrated and uncalibrated direct digital images. Endodontic files of known lengths and ISO sizes were used in 10 single-rooted, relatively straight teeth within cadaver specimens. The crowns of the teeth were ground flat and an orthodontic wire of known length was secured to the coronal surface. This wire was placed mesiodistally and perpendicular to the root and served as the reference point for the file measurement and as a calibration reference length. A #20 file was hand-measured to a length that reached the apical third of each tooth. It was inserted and a radiographic image was secured. The instrument was remeasured three additional times at different lengths on the same tooth and reinserted before each image acquisition. Thus 40 digital images were acquired using a GE X-ray unit and a Schick Computed Dental Radiography (CDR) #2 sensor. These images were placed in random order, and an independent, blinded investigator determined the file lengths using on-screen calibrated and uncalibrated measurement of the CDR image with a straight-line and multiple-line measuring technique. The experimental measurements were compared with each other and with the known clinical measurements. A two-way analysis of variance indicated that there was a statistically significant difference showing that the calibrated measurements were more accurate than the uncalibrated measurements (p = 0.0001), and there was no significant difference between the straight-line and multiple-line measuring techniques (p = 0.14).

Comparison of 5 protocols based on their abilities to use data extracted from digitized clinical radiographs to discriminate between patients with gingivitis and periodontitis.

BACKGROUND: This study was undertaken to compare 5 digital analytic protocols for their abilities to extract data from digital clinical radiographs and discriminate between patients with gingivitis and periodontitis. METHODS: Five digital-image analysis protocols were compared for their abilities to discriminate between two groups of 24 patients each. One group was diagnosed with healthy gingiva (or gingivitis) and the second with periodontitis. These groups were previously evaluated in published studies that used fractal and morphologic analyses. Pre-existing clinical radiographs for each patient were digitized and regions of interest (ROIs) were placed on interdental bone in mandibular posterior quadrants. The 5 protocols used were: 1) MGB: a median filtration to remove high-frequency noise, a Gaussian filtration to remove low-frequency noise, binarization of the resulting image, and quantification of the black pixels; 2) MGBS: the same protocol as MGB except for a skeletonization of the binary image and a quantification of the skeleton's pixels; 3) GBS: Gaussian filtration, binarization (thresholding on the mean pixel value) of the resulting image, skeletonization, and quantification of the pixels of the skeleton; 4) NS: normalization, skeletonization, and quantification of the skeleton's pixels; and 5) S: a variation of NS, except normalization was not used. The resulting values for the 2 patient groups were compared with Mann-Whitney U tests and effect likelihood-ratio test. RESULTS: For digitized radiographs, the mean gray-scale value (+/- standard deviation) for gingivitis patients was 183.22 +/- 18.53 and for periodontitis patients 181.26 +/- 17.20. Mann-Whitney U tests resulted in the following P values for these protocols: MGBS <0.01; S <0.01; GBS <0.01; NS <0.01; and MGB <0.83. Effect likelihood-ratio tests indicated that only MGBS and S significantly contributed to models containing the other factors. CONCLUSIONS: Small variations to protocols affected the strength of the discrimination between the gingivitis and periodontitis groups. While there is potential for morphologic analysis to be used to discriminate between patients with gingivitis and periodontitis, a robust technique was not identified.

Comparison of morphological measurements extracted from digitized dental radiographs with lumbar and femoral bone mineral density measurements in postmenopausal women.

BACKGROUND: We set out to determine whether morphologic measurements extracted from digitized images of bite-wing radiographs correlated with lumbar and femoral bone mineral density (BMD) measurements in 45 postmenopausal women who had no or only mild periodontal disease (no probing depths >5 mm). METHODS: Lumbar spine and femoral BMDs were determined by dual-energy x-ray absorptiometry. Vertical bite-wing radiographs were taken and digitized. Crestal and apical regions of interest (ROIs) were drawn on the digital images of the maxillary and mandibular alveolar bone on the patient's right and left sides. For each patient, a single morphologic measurement was made for each of 8 ROIs. Correlation analysis was performed to determine the strengths of the relationships between the morphologic measurements made at the 8 locations and between these morphologic measurements and BMD measurements. RESULTS: The correlations (r) between the morphologic operator (MO) measurements and lumbar spine and femoral BMDs were weak (mean r = 0.02, range = 0.32 to -0.26) and not statistically significant, with no clear trends discernible. Correlations between MO measurements made at the 8 alveolar sites were also weak (mean r = 0.05, range = 0.35 to -0.38) and not statistically significant. CONCLUSIONS: The MO measurements used in this study were weakly correlated with lumbar spine and femoral BMDs, with no clear trends discernible in this population of postmenopausal women with no or mild periodontal disease.

Comparison of direct digital and conventional radiography for the detection of proximal surface caries in the mixed dentition.

PURPOSE: The aim of this study was to compare the performance of direct digital radiography and traditional dental radiography for the detection of proximal surface dental caries in the mixed dentition. METHODS: 15 quadrants of extracted teeth, arranged from the primary canine to permanent first molar, were imaged using direct digital (Schick Technologies, Long Island City, NY, USA) and conventional films (D-speed and E-speed Plus; Eastman Kodak Co., Rochester, NY, USA). Five pediatric dentists viewed the images and scored the 270 proximal surfaces for presence of caries on a 5 point scale and extent of caries on a 4 point scale. The teeth were sectioned and viewed microscopically to determine the gold standard. Receiver operating characteristic (ROC) analysis and analysis of variance (ANOVA) were used to evaluate the viewer's performance for detecting proximal caries using the 3 different image receptor types. RESULTS: Experienced examiners were significantly more accurate in diagnosis of proximal surface caries using either D-speed or E-speed Plus films than they were using the direct digital receptor. The mean areas under the ROC curve (Az) for the viewers were 0.7595 for D-speed film, 0.7557 for E-speed Plus film, and 0.5928 for the direct digital receptor. The results also indicated that selected viewers' accuracy increased when viewing the direct digital images a second time. CONCLUSION: CCD based direct digital radiography was not as accurate as conventional film images for the purpose of diagnosing proximal surface caries in the mixed dentition. However, the results imply that with increased experience, direct digital images may be as accurate as conventional film based images for diagnosis.

Measurement of endodontic file lengths: a density profile plot analysis.

The purpose of this study was to evaluate measurements of endodontic files of known length and diameter using a density profile plot analysis of digital images. Ten single-rooted teeth with relatively straight roots in cadaver specimens were used. The crowns of the teeth were removed and a rectangular orthodontic wire, 5.13 mm in length, was placed horizontally on the occlusal surface to serve as a calibration reference point. The #8, #10, #15, and #20 FlexOFiles were measured to the nearest 0.5 mm and then placed to four working lengths that terminated within the apical third of each root. A GE X-ray unit and a Schick CDR #2 sensor were used to digitally acquire 160 images. The digital images were placed in random order and an independent, blinded investigator determined the file length using a density profile plot analysis. The measurements generated by the histogram analysis (experimental) were compared with the original clinical measurements. The paired t test, intraclass correlation coefficient, and the Bradley-Blackwood test were used to assess reliability. The results revealed that the means of the experimental measurements of all file sizes were within 0.5 mm of the known lengths and were always shorter than the known lengths. Also, the larger the file size the less deviation from the known lengths: #20, -0.16 mm (p = 0.0001); #15, -0.21 mm (p = 0.0001); #10, -0.34 mm (p = 0.0001); and #8, -0.45 mm (p = 0.0001). This study demonstrated that the density profile plot analysis might be a useful adjunct for the measurement of endodontic file lengths on a digital image.

Assessing dentin color changes from nightguard vital bleaching.

BACKGROUND: At-home bleaching with 10 percent carbamide peroxide in a custom-fitted tray has been reported to change the color of dentin. The purpose of this study was to validate the color change of dentin and to determine whether the color change was uniform or occurred from the outside (the dentinoenamel junction) to the inside (the pulpal wall). METHODS: The authors sectioned 10 extracted human teeth incisogingivally through the midfacial long axis, and sealed their cut surface against glass microscope slides. Identifying marks were placed on the glass over the tooth sections to serve as a color control and in the dentinal areas closest to the dentinoenamel junction and the pulpal wall. Teeth were bleached for 10 days with 10 percent carbamide peroxide. Photographs were taken from the glass-covered side of the teeth, digitized and converted to gray-scale levels (consisting of 256 shades of gray ranging from black to white). Marked areas were measured with a National Institutes of Health Image software program and analyzed statistically for changes in lightness between the control marks and the inner and outer dentinal marks over time. RESULTS: Paired t-tests and analysis of variance indicated a significant increase in lightness (P = .01) for the inner and outer dentinal areas during bleaching compared with the control areas. No significant differences were found in the rate of change for the inner and outer dentinal areas (P = .89). CONCLUSIONS: The increase in lightness confirms that a significant color change occurred in the dentin during bleaching with 10 percent carbamide peroxide. This change occurred throughout the dentin at a uniform rate, rather than from the outside inward. CLINICAL IMPLICATIONS: The results of this study show that at-home bleaching with 10 percent carbamide peroxide can change the color of dentin, which is important to treat intrinsic stains from tetracycline treatment, trauma and aging or inherited discolorations. The bleaching material easily penetrates the tooth to change the dentin color at the same rate throughout, indicating that the type of stain may be the important factor in determining bleaching success.

The effect of region of interest variations on morphologic operations data and gray-level values extracted from digitized dental radiographs.

OBJECTIVE: To determine the correlations among morphologic operations (MO) values and the correlations among gray-level values for regions of interest (ROIs) placed at various locations on digital images of alveolar bone for 45 patients. STUDY DESIGN: As part of a larger study, up to 7 vertical bite-wing radiographs were taken and digitized for each of 45 patients. Sets of 2 rectangular ROIs were placed on the digitized images of interdental alveolar bone at 4 locations for each patient. The ROIs (1 crestal and 1 apical) were placed between second premolars and first molars in all 4 dental quadrants. Gray-level values were measured, and MO analysis was performed on each ROI. Descriptive statistics were calculated and correlations determined. RESULTS: Paired correlations (such as apical vs crestal, left vs right, maxillary apical vs mandibular apical) of MO values were weak (r = 0.01-0.21), but corresponding correlations for gray-level values were relatively strong (r = 0. 60-0.92). CONCLUSION: MO values varied with ROI location considerably more than did gray-level values. Additionally, ROI size and shape apparently affected MO data. Accurate placement and documentation of ROIs appear to be critical considerations in analyses that use MOs.

Modulation of the insulin-like growth factor system by chronic alcohol feeding.

Insulin-like growth factor (IGF)-I is a potent anabolic agent that plays an important role in regulating muscle protein balance. Alterations in one or more of the various components of the IGF system may be in part responsible for the muscle wasting that accompanies chronic alcohol consumption. The purpose of the present study was to characterize changes in the growth hormone-IGF axis produced by chronic alcohol consumption in rats. After 8 weeks of alcohol feeding, the IGF-I concentration was decreased in plasma (31%) as well as in the liver and skeletal muscle (40-50%), compared with pair-fed control animals. In addition, alcohol consumption decreased IGF-I mRNA abundance in liver and muscle (approximately 50%). IGF-I content in duodenum and kidney, however, was not altered by alcohol feeding. Concomitantly, the relative concentration of IGF binding protein (IGFBP)-1 was increased in plasma, liver, and muscle of alcohol-fed rats, compared with control values. In contrast, no changes in the plasma concentrations of IGFBP-2, -3, or -4 were detected in alcohol-fed rats at this time point Previous studies have indicated that elevations in glucocorticoids or decreases in insulin or growth hormone might be responsible for the decrease in IGF-I and/or the increase in IGFBP-1 in other catabolic conditions. However, there was no difference in the plasma concentrations of these hormones between alcohol-fed and control animals in this study. These data indicate that chronic alcohol feeding in rats decreases IGF-I and increases IGFBP-1 in the circulation and in skeletal muscle and that these changes appear to be independent of changes in classical hormonal regulators of the IGF system. The observed alterations in the IGF system are consistent with a reduction in the anabolic actions of IGF-I induced by chronic alcohol consumption.

A comparison of 2 patient populations using fractal analysis.

This study was undertaken to demonstrate that the fractal dimensions calculated using digitized non-standardized, clinical radiographs of mandibular alveolar bone from a population of patients diagnosed with periodontitis are statistically different from fractal dimensions calculated from another population diagnosed as having gingivitis or healthy gingiva. The fractal dimension was calculated using a public domain fractal analysis program distributed by the National Institutes of Health (NIH). Fractal dimensions were calculated from digitized clinical radiographs for 29 patients diagnosed with healthy gingiva and/or gingivitis and 32 patients diagnosed with periodontitis and compared. To estimate the reproducibility of the technique, we recalculated the fractal dimension from images of the gingivitis patients 3 months after the original calculations and compared them to the originals. A 2 sample, 2-tailed Student t test showed the gingivitis data group to be different from the periodontitis data group (P = 0.0012). The original gingivitis and repeat gingivitis groups fractal dimension calculation were the same and analysis showed the two data sets were not significantly different (P = 0.99). We found that: 1) fractal dimensions could be used to distinguish between gingivitis and periodontitis patient groups; 2) fractal dimensions could be calculated from non-standardized clinical radiographs; and 3) fractal dimensions for gingivitis patients were reproducible over a 3-month period.

Morphologic operations used to distinguish between two patient populations differing in periodontal health.

OBJECTIVES: This study was conducted to determine whether morphologic operation procedures applied to digitized, non-standardized, clinical radiographs of mandibular alveolar bone could be used to distinguish between a population of patients diagnosed with periodontitis and a population of patients either diagnosed with gingivitis or having healthy gingivae. STUDY DESIGN: Two groups, one consisting of 29 patients who either had healthy gingivae or had been diagnosed with gingivitis and the other consisting of 32 patients who had been diagnosed with periodontitis, were compared. Pre-existing clinical radiographs were digitized, and for each patient three to six regions of interest were placed on an image of the mandibular posterior region of the interdental bone. The regions of interest were processed under two morphologic-operations protocols, and a mean density (referred to as an MO number) was calculated for each patient. With paired t-tests, the resulting MO numbers for the two groups were compared. RESULTS: The two populations were statistically different (p < 0.05). CONCLUSION: The results of this study indicate that morphologic operations have the potential to differentiate between patient groups differing in periodontal health.

Implant site assessment using panoramic cross-sectional tomographic imaging.

OBJECTIVES: The purpose of this study was to evaluate the ability of two different panoramic imaging systems to produce cross-sectional images with accurate vertical dimensions of the posterior mandible. STUDY DESIGN: Three partially edentulous human cadaver mandibles were used for this study. On each mandible, three potential implant sites were arbitrarily identified in an area between the mental foramen and the ascending ramus. Each site was imaged using two different panoramic machines. Using each image, the mandible's outline, cortical thickness, and position of the mandibular canal were traced on clear acetate film. The mandibles were then sectioned at each site to serve as a gold standard. The cadaver sections and tracings (corrected for magnification) were measured, recording the overall mandibular height, distance from the crest of the ridge to the superior aspect of the mandibular canal, and the thickness of the cortical bone at the most inferior aspect of the mandible. RESULTS: There were no significant differences between either of the system's image measures and the gold standard when considering the distance between the crest and the mandibular canal. Differences were noted between the systems measures and the gold standard in the assessment of the cortical bone thickness and the overall mandibular height. CONCLUSIONS: Both imaging systems can be useful for vertical measurements of a potential implant site in the posterior mandible.

The significance of subendothelial von Willebrand factor.

von Willebrand factor (vWf) serves to bridge between receptors on the platelet cytoplasmic membrane and the extracellular matrix. In addition to circulating in plasma, vWf is deposited into the extracellular matrix of the subendothelium where it is associated with type VI collagen microfibrils, but not with the elastin-associated microfibrils which are present in the deepest portion of the subendothelium at the zone of the internal elastic lamina. The reaction of platelets to type VI collagen in flow systems is qualitatively different from the shear rate dependent adhesion and aggregation response which is observed with fibrillar type I collagen, exhibiting a response only at low shear rates. The adhesion response to type VI collagen is dependent upon vWf, GP Ib and the GP IIb-IIIa complex. Platelets exposed to purified fibrillin-containing elastin-associated microfibrils adhere and aggregate at low shear rates; this response appears to involve GP IIb-IIIa but not GP Ib. The data are consistent with the hypothesis that type VI collagen is a physiologically relevant binding site for vWf in subendothelium.

The effect of image variations on fractal dimension calculations.

OBJECTIVES: We used digitized dental radiographs of alveolar bone to test the hypothesis that the fractal dimension, as calculated with the program "ImageFractal" was independent of variations in X-ray exposure, beam alignment, and region of interest placement. STUDY DESIGN: The radiographic data set consisted of 72 radiographs digitized with 200 microns pixels. Radiographs were obtained with the use of three time settings and two alignments. Rectangular regions of interest were placed on each digital image over the interdental bone between the mandibular first and second molars on six hemimandibles. Each of six hemimandibles had identical copies of a unique region of interest placed on every image in its series. New regions were made 3 months later. A fractal dimension was computed from each region of interest with the caliper method included in ImageFractal, a public domain program available through National Institutes of Health. The resulting fractal dimensions were evaluated with two repeated measures analysis of variance. RESULTS: No significant differences were found between the fractal dimensions calculated for baseline images and those from overexposed and underexposed images, from images with 4 to 6 degrees of alignment variations, or from repeat regions of interest. CONCLUSION: The results support the hypothesis that fractal dimensions derived from digitized dental radiographs are not affected by variations in exposure or small variations in alignment and imply an absolute region of interest placement may not be necessary. However, caution should be used with the use of the fractal dimension to discriminate among alveolar bone variations until further research is performed.

The effect of clenbuterol and recombinant erythropoietin on tumor growth and the anemia caused by the Walker 256 carcinosarcoma.

In patients with advanced cancer, anemia is a common complication indicative of a poor prognosis. Attempts to alleviate this have met with mixed success and interventions including erythropoietin often fail to elicit an appropriate response. We have used rats implanted with the Walker 256 carcinosarcoma as a model of non-responsive anemia. This study demonstrates that the provision of recombinant erythropoietin in the presence of clenbuterol, a beta2 agonist, attenuates both the cancer induced anemia and the growth of the tumor in this model. We hypothesize that this treatment relieves the tumor induced inhibition of hematopoiesis, which allows for not only an increase in hematocrit but an increased immunosurveillance resulting in tumor suppression.

The effect of varying the region of interest on calculations of fractal index.

OBJECTIVES: To compare the effect of using regions of interest (ROIs) of different size and shape on the fractal index of alveolar bone. STUDY DESIGN: Two sets of clinical posterior bitewing radiographs were used to calculate the fractal index (S). Two comparisons were made. First, S was calculated from large interdental ROIs that included small amounts of root structure and compared with S from small ROIs that included no root structures. Then S was calculated from large interdental ROIs (similar to those used for the first set) and compared with S calculated from ROIs that included nearly all of the mandibular alveolar bone (and adjacent root) present on the bitewing. RESULTS: For the first comparison, paired t-tests showed that fractal indices calculated with the large ROIs were significantly different from the respective indices calculated from the small ROIs (P < 0.001). For the second comparison, the fractal indices calculated from the large quadrant ROIs were not significantly different from those calculated from the large ROIs (P = 0.120). CONCLUSION: ROI size and shape may affect the results of fractal analysis of alveolar bone.