Tryptophan degradation in women with breast cancer: a pilot study

Background

Altered tryptophan metabolism and indoleamine 2,3-dioxygenase activity are linked to cancer development and progression. In addition, these biological factors have been associated with the development and severity of neuropsychiatric syndromes, including major depressive disorder. However, this biological mechanism associated with both poor disease outcomes and adverse neuropsychiatric symptoms has received little attention in women with breast cancer. Therefore, a pilot study was undertaken to compare levels of tryptophan and other proteins involved in tryptophan degradation in women with breast cancer to women without cancer, and secondarily, to examine levels in women with breast caner over the course of chemotherapy.

Findings

Blood samples were collected from women with a recent diagnosis of breast cancer (n = 33) before their first cycle of chemotherapy and after their last cycle of chemotherapy. The comparison group (n = 24) provided a blood sample prior to breast biopsy. Plasma concentrations of tryptophan, kynurenine, and tyrosine were determined. The kynurenine to tryptophan ratio (KYN/TRP) was used to estimate indoleamine 2,3-dioxygenase activity. On average, the women with breast cancer had lower levels of tryptophan, elevated levels of kynurenine and tyrosine and an increased KYN/TRP ratio compared to women without breast cancer. There was a statistically significant difference between the two groups in the KYN/TRP ratio (p = 0.036), which remained elevated in women with breast cancer throughout the treatment trajectory.

Conclusions

The findings of this pilot study suggest that increased tryptophan degradation may occur in women with early-stage breast cancer. Given the multifactorial consequences of increased tryptophan degradation in cancer outcomes and neuropsychiatric symptom manifestation, this biological mechanism deserves broader attention in women with breast cancer.

Challenges in interpreting cytokine biomarkers in biobehavioral research: a breast cancer exemplar

PURPOSE

This report extends the findings of a prior study comparing the level of plasma cytokines in women with breast cancer to those of women with a benign breast biopsy with the addition of a normal comparison group. The results of this three-group comparison are presented as background for discussing several methodologic challenges for biobehavioral research in inflammatory-based conditions.

METHOD

This study used a descriptive, cross-sectional design to compare the levels of plasma cytokines in women with breast cancer, women with a benign breast biopsy, and a normal comparison group. The levels of 17 cytokines were measured using multiplex bead array assays (Bio-Plex®). Data analysis included a variety of descriptive and graphical techniques to illustrate between-group differences in cytokine profiles.

RESULTS

The levels of plasma cytokines in the sample of 35 women who had recently been diagnosed with breast cancer, 24 women with a suspicious breast mass, who subsequently were found to have a benign breast biopsy, and 33 women in a normal comparison group present a background for discussing the implications of extreme between-group differences for biobehavioral nursing research. Both the levels of individual cytokines and their patterns were distinctly different in the three groups.

CONCLUSION

The exemplar presented from the three-group comparison has implications for planning biobehavioral nursing research in patients with conditions characterized by inflammation.

Variance in abdominal wall anatomy and port placement in women undergoing robotic gynecologic surgery

STUDY OBJECTIVES

To estimate whether variability in the size and ratios of the lower and upper abdomen exist in women undergoing robotic gynecologic surgery and whether demographic variables are significantly associated, and to determine the association between abdominal wall dimensions and supraumbilical robotic port placement.

DESIGN

Prospective cohort study (Canadian Task Force classification II-2).

SETTING

University teaching hospital.

PATIENTS

Seventy-eight women undergoing robotic surgery between May 2008 and March 2009.

INTERVENTION

Measurements from the symphysis pubis to the umbilicus (lower abdomen), umbilicus to the xyphoid process (upper abdomen), and distance between the anterior superior iliac crests were obtained at surgery. A multiple linear regression model was created to determine the relationships between abdominal wall measurements, demographic variables, and need for supraumbilical robotic port placement.

MEASUREMENTS AND MAIN RESULTS

Fifty-six white and 22 black women were enrolled. Mean lower abdominal length was significantly affected by body mass index (BMI) (p <.001) and race (p = .006), with white women having longer measurements (17.1 cm vs 15 cm). Mean lower abdominal width was independent of age (p = .95) or race (p = .98), but was significantly correlated with BMI (p <.001). Mean upper abdominal length correlated with BMI (p <.001) and age (p = .03) but not race (p = .13). Ratios of bottom to top were significantly affected by race (p = .002) and age (p = .008) but not BMI (p = .07). Adjustments to port placement above the umbilicus were made in 44 of the 74 women (59.5%). Those who required supraumbilical port placement had a significantly shorter mean (SD) distance between the symphysis pubis and the umbilicus (14.99 [1.36] vs 18.55 [2.21]; p <.001).

CONCLUSIONS

Significant variability in abdominal wall anatomy exists in women undergoing robotic gynecologic surgery, and the need for supraumbilical robotic port placement is common.

Persistence of cognitive impairment after resolution of overt hepatic encephalopathy

BACKGROUND & AIMS

In patients with cirrhosis, hepatic encephalopathy (HE) has acute but reversible as well as chronic components. We investigated the extent of residual cognitive impairment following clinical resolution of overt HE (OHE).

METHODS

Cognitive function of cirrhotic patients was evaluated using psychometric tests (digit symbol, block design, and number connection [NCT-A and B]) and the inhibitory control test (ICT). Improvement (reduction) in ICT lures and first minus second halves (DeltaL(1-2)) were used to determine learning of response inhibition. Two cross-sectional studies (A and B) compared data from stable cirrhotic patients with or without prior OHE. We then prospectively assessed cognitive performance, before and after the first episode of OHE.

RESULTS

In study A (226 cirrhotic patients), 54 had experienced OHE, 120 had minimal HE, and 52 with no minimal HE. Despite normal mental status on lactulose after OHE, cirrhotic patients were cognitively impaired, based on results from all tests. Learning of response inhibition (DeltaL(1-2) > or =1) was evident in patients with minimal HE and no minimal HE but was lost after OHE. In study B (50 additional patients who developed > or =1 documented OHE episode during follow-up), the number of OHE hospitalizations correlated with severity of residual impairment, indicated by ICT lures (r = 0.5, P = .0001), digit symbol test (r = -0.39, P = .002), and number connection test-B (r = 0.33, P = .04). In the prospective study (59 cirrhotic patients without OHE), 15 developed OHE; ICT lure response worsened significantly after OHE (12 before vs 18 after, P = .0003), and learning of response inhibition was lost. The 44 patients who did not experience OHE did not have deteriorations in cognitive function in serial testing.

CONCLUSIONS

In cirrhosis, episodes of OHE are associated with persistent and cumulative deficits in working memory, response inhibition, and learning.

Persistence of cognitive impairment after resolution of overt hepatic encephalopathy

BACKGROUND & AIMS

In patients with cirrhosis, hepatic encephalopathy (HE) has acute but reversible as well as chronic components. We investigated the extent of residual cognitive impairment following clinical resolution of overt HE (OHE).

METHODS

Cognitive function of cirrhotic patients was evaluated using psychometric tests (digit symbol, block design, and number connection [NCT-A and B]) and the inhibitory control test (ICT). Improvement (reduction) in ICT lures and first minus second halves (DeltaL(1-2)) were used to determine learning of response inhibition. Two cross-sectional studies (A and B) compared data from stable cirrhotic patients with or without prior OHE. We then prospectively assessed cognitive performance, before and after the first episode of OHE.

RESULTS

In study A (226 cirrhotic patients), 54 had experienced OHE, 120 had minimal HE, and 52 with no minimal HE. Despite normal mental status on lactulose after OHE, cirrhotic patients were cognitively impaired, based on results from all tests. Learning of response inhibition (DeltaL(1-2) > or =1) was evident in patients with minimal HE and no minimal HE but was lost after OHE. In study B (50 additional patients who developed > or =1 documented OHE episode during follow-up), the number of OHE hospitalizations correlated with severity of residual impairment, indicated by ICT lures (r = 0.5, P = .0001), digit symbol test (r = -0.39, P = .002), and number connection test-B (r = 0.33, P = .04). In the prospective study (59 cirrhotic patients without OHE), 15 developed OHE; ICT lure response worsened significantly after OHE (12 before vs 18 after, P = .0003), and learning of response inhibition was lost. The 44 patients who did not experience OHE did not have deteriorations in cognitive function in serial testing.

CONCLUSIONS

In cirrhosis, episodes of OHE are associated with persistent and cumulative deficits in working memory, response inhibition, and learning.

Is laminin gamma-1 a candidate gene for advanced pelvic organ prolapse?

OBJECTIVE

We sought to determine allele frequencies of 3 LAMC1 single nucleotide polymorphisms (SNPs) in Caucasian and African American (AA) women with stage>II pelvic organ prolapse (POP) (cases) and in ethnicity-matched controls with stage<II POP. We also sought to determine if LAMC1 is associated with POP within ethnic groups.

STUDY DESIGN

Allelic discrimination was performed for LAMC1 SNPs rs10911193 (C/T), rs20563 (A/G), and rs20558 (T/C). SNP and haplotype-specific tests were used to examine associations among POP, ethnicity, and LAMC1.

RESULTS

In all, 411 women were enrolled. Significant differences in allele and haplotype frequencies existed among AAs and Caucasians: rs10911193 "T" (P=.0014); rs20563 "G" (P<.0001); rs20558 "C" (P<.0001); rs20563, rs20558 "GC" (P<.0001); and rs20563, rs20558 "AT" (P<.0001). No significant associations between POP and LAMC1 SNPs or haplotypes were found within ethnicities.

CONCLUSION

While significant differences were identified between AA and Caucasian women, no associations were found between any LAMC1 gene variant and advanced POP.

Left ventricular mass, abdominal circumference and age: the Fels longitudinal study

PURPOSE

To determine the relationship of abdominal circumference with increased left ventricular mass (LVM) from young adulthood into old age.

METHODS

Cross-sectional echocardiographic images were taken from 182 men and 220 women in the Fels Longitudinal Study 20 to 75 years of age to determine left ventricular mass. Left ventricular mass was divided by stature raised to the power of 2.7 (LVM/ht2.7) in order to minimize the impact of heart size variation from body size without overcompensating for the adverse effect of obesity. Abdominal circumference was measured and BMI calculated from stature and weight and categories of overweight, obesity and abdominal obesity were determined using published cut points. Regression models were used to describe the relationships of age, abdominal circumference, BMI and self-reported physical activity to LVM/ht2.7.

RESULTS

Age, abdominal circumference and BMI were each positively and significantly related to an increased LVM/ht2.7 in men and women (p < 0.05). In the men, multivariate models indicated that abdominal circumference and BMI were both significantly related to an increased LVM/ht2.7, but the inclusion of BMI in these models for the women reduced the association of abdominal circumference and physical activity below significant levels. In the men, there was also a quadratic association of abdominal circumference with LVM/ht2.7 that was significant along with BMI and physical activity. Sex-specific logistic regressions with BMI and abdominal circumference obesity categories did not change or improve the initial findings in men or women.

CONCLUSIONS

In women, increases in abdominal fatness as reflected in abdominal circumference at any age are linearly related to an increase in LVM/ht2.7, but the relationship of overall fatness as reflected in BMI with LVM/ht2.7 is stronger. In men, both abdominal fatness and overall fatness at any age are linearly related to an increase LVM/ht2.7. However, the significant curvilinear association of abdominal circumference and a linear association of BMI and physical activity with LVM/ht2.7 indicate the possible positive covariate relationship of overall muscle mass with LVM/ht2.7. This reflects the physiological changes with age and demonstrate, in part, the complexity of the interpretations of the inter associations of body composition, the cardiovascular system and the aging process, but the impact among the elderly and the known inadequacy of BMI at these ages remains an area for continued clinical study.

Minimal hepatic encephalopathy is associated with motor vehicle crashes: the reality beyond the driving test

Patients with minimal hepatic encephalopathy (MHE) have impaired driving skills, but association of MHE with motor vehicle crashes is unclear. Standard psychometric tests (SPT) or inhibitory control test (ICT) can be used to diagnose MHE. The aim was to determine the association of MHE with crashes and traffic violations over the preceding year and on 1-year follow-up. Patients with cirrhosis were diagnosed with MHE by ICT (MHEICT) and SPT (MHESPT). Self and department-of-transportation (DOT)-reports were used to determine crashes and violations over the preceding year. Agreement between self and DOT-reports was analyzed. Patients then underwent 1-year follow-up for crash/violation occurrence. Crashes in those with/without MHEICT and MHESPT were compared. 167 patients with cirrhosis had DOT-reports, of which 120 also had self-reports. A significantly higher proportion of MHEICT patients with cirrhosis experienced crashes in the preceding year compared to those without MHE by self-report (17% vs 0.0%, P = 0.0004) and DOT-reports (17% vs 3%, P = 0.004, relative risk: 5.77). SPT did not differentiate between those with/without crashes. A significantly higher proportion of patients with crashes had MHEICT compared to MHESPT, both self-reported (100% vs 50%, P = 0.03) and DOT-reported (89% vs 44%, P = 0.01). There was excellent agreement between self and DOT-reports for crashes and violations (Kappa 0.90 and 0.80). 109 patients were followed prospectively. MHEICT patients had a significantly higher future crashes/violations compared to those without (22% vs 7%, P = 0.03) but MHESPT did not. MHEICT (Odds ratio: 4.51) and prior year crash/violation (Odds ratio: 2.96) were significantly associated with future crash/violation occurrence.

CONCLUSION

Patients with cirrhosis and MHEICT have a significantly higher crash rate over the preceding year and on prospective follow-up compared to patients without MHE. ICT, but not SPT performance is significantly associated with prior and future crashes and violations. There was an excellent agreement between self- and DOT-reports.

Predictive ability of childhood metabolic components for adult metabolic syndrome and type 2 diabetes

OBJECTIVE

To estimate sensitivity, specificity, and positive and negative predictive values of components of the metabolic syndrome (MetS) during childhood for MetS and type 2 diabetes (T2D) in adulthood.

STUDY DESIGN

Data from 3 major studies-the Fels Longitudinal Study, the Muscatine Study, and the Princeton Follow-up Study-were combined to examine how thresholds of metabolic components during childhood determine adult MetS and T2D. Available metabolic components examined in the 1789 subjects included high-density lipoprotein, triglyceride levels, glucose, and percentiles for body mass index, waist circumference, triglycerides, and systolic and diastolic blood pressures. Sensitivity, specificity, and positive and negative predictive values for a refined set of component threshold values were examined individually and in combination.

RESULTS

Sensitivity and positive predictive values remained low for adult MetS and T2D for individual components. However, specificity and negative predictive values were fairly high for MetS and exceptionally so for T2D. In combination, having 1 or more of the components showed the highest sensitivity over any individual component and high negative predictive value. Overall, specificity and negative predictive values remained high whether considering individual or combined components for T2D.

CONCLUSIONS

Sensitivity and positive predictive values on the basis of childhood measures remained relatively low, but specificity and negative predictive values were consistently higher, especially for T2D. This indicates that these components, when examined during childhood, may provide a useful screening approach to identifying children not at risk so that further attention can be focused on those who may be in need of future intervention.

Prolonged juvenile States and delay of cardiovascular and metabolic risk factors: the Fels Longitudinal study

OBJECTIVES

To ascertain the influence of such a prolonged juvenile state on delaying the onset of the metabolic syndrome, cardiovascular disease, and type 2 diabetes mellitus later in life.

STUDY DESIGN

We define prolongation of a juvenile state as a retarded tempo of growth, determined by the timing of peak height velocity in each subject and relate the retarded tempo of growth to metabolic syndrome, cardiovascular disease, and type 2 diabetes mellitus later in life by use of serial data of 237 study participants (119 men and 118 women) enrolled in the Fels Longitudinal study.

RESULTS

Children who matured early tended to have greater body mass index, waist circumference, and percent of body fat and were more likely to have adverse cardiovascular risk profiles than children who matured late. The differences in these risk factors between early and late maturers were significant for percent body fat, fasting plasma triglycerides, and fasting plasma insulin.

CONCLUSIONS

The analyses disclosed a clear separation between early and late maturers in the appearance of these risk factors in young adulthood.

Additive utility of family history and waist circumference to body mass index in childhood for predicting metabolic syndrome in adulthood

OBJECTIVE

To determine whether waist circumference (WC) and family history of disease increase the predictive utility of body mass index (BMI) for adult metabolic syndrome (MetS).

STUDY DESIGN

A subsample of 161 men and women from the Fels Longitudinal Study with childhood and adulthood measures were analyzed. Using logistic regression, childhood BMI categories (50th, 75th, and 85th percentiles), WC categories (75th and 90th percentiles), and family history of type 2 diabetes mellitus or cardiovascular disease were modeled separately and in combinations to predict adult MetS. Predicted probabilities and c-statistics were compared across models.

RESULTS

The addition of family history to BMI improved the predicted probability of adult MetS from 29% to 52% (Deltac-statistic = 0.13). The combination of WC and BMI was more predictive than BMI alone but did not outperform the combination of family history and BMI. In 3 of the 4 models with a combination of family history, WC, and BMI, the predicted probability of adult MetS did not exceed that from the combination of family history and BMI.

CONCLUSIONS

Family history of type 2 diabetes or cardiovascular disease is a useful addition to BMI in childhood to predict the future risk of adult MetS.

Long-Term Outcomes After Catheter Ablation of Cavo-Tricuspid Isthmus Dependent Atrial Flutter

Background— Despite the success of catheter ablation of cavotricuspid isthmus–dependent atrial flutter (AFL), important postablation outcomes are ill-defined. The purpose of our study was to analyze long-term outcomes after catheter ablation of cavotricuspid isthmus–dependent AFL.

Methods and Results— A meta-analysis was performed of articles reporting clinical outcomes after catheter ablation of AFL published between January 1988 and July 2008. The analysis included 158 studies comprising 10 719 patients (79% men, 59.8�0.5 years old, 46% left atrial enlargement, 46% heart disease, 42% with history of atrial fibrillation, 14.3�0.4 months of follow-up). The overall acute success rate adjusted for reporting bias was 91.1% (95% CI, 89.5 to 92.4), 92.7% (95% CI, 90.0 to 94.8) for 8- to 10-mm tip/or irrigated radiofrequency catheters, and 87.9% (95% CI, 84.2 to 90.9) for 4- to 6-mm tip catheters ( P >0.05). Atrial flutter recurrence rates were significantly reduced by use of 8- to 10-mm tip or irrigated radiofrequency catheters (6.7% versus 13.8%, P <0.05) and by use of bidirectional cavotricuspid isthmus block as a procedural end point (9.3% versus 23.6%, P <0.05). The AFL recurrence rate did not increase over time. The overall occurrence rate of atrial fibrillation after AFL ablation was 33.6% (95% CI, 29.7 to 37.3) but was 52.7% (95% CI, 47.8 to 57.6) in patients with a history of atrial fibrillation before ablation and 23.1% (95% CI, 17.5 to 29.9) in those without atrial fibrillation before ablation ( P <0.05). The incidence of atrial fibrillation increased over time in both groups; however, 5 years after ablation, the incidence of atrial fibrillation was similar in those with and without atrial fibrillation before ablation. The acute complication rate was 2.6% (95% CI, 2 to 3). The mortality rate during follow-up was 3.3% (95% CI, 2.4 to 4.5). Antiarrhythmic drug use after ablation was 31.6% (95% CI, 25.6 to 37.8). The long-term use of coumadin was 65.9%, (95% CI, 43.8 to 82.8). Quality of life data were very limited.

Conclusions— AFL ablation is safe and effective. Ablation technology and procedural end points have greater influences on AFL recurrences than on acute ablation success rates. Atrial fibrillation is common after AFL ablation. Almost one third of patients take antiarrhythmic drugs after AFL ablation. Atrial fibrillation before AFL ablation may indicate a more advanced state of electric disease.

The effect of fatigue on driving skills in patients with hepatic encephalopathy

OBJECTIVES

Hepatic encephalopathy, both overt (OHE) and minimal (MHE), is associated with poor quality of life and fatigue. The aim of this study was to define the effect of fatigue on driving skills in MHE and OHE patients.

METHODS

Cirrhotics and age/education-matched controls were administered a psychometric battery of tests to diagnose MHE. Cirrhotics with recent OHE on lactulose were also included. All subjects underwent a driving simulation; to assess fatigue, the second half performance was compared with the first half of the simulation. The outcomes were collisions, speeding, road excursions, and center crossings. Actual driving-associated fatigue was assessed by the American Medical Association (AMA) driver survey.

RESULTS

A total of 100 cirrhotics (51 MHE, 27 no MHE, and 22 OHE) and 67 controls were included. A significantly higher proportion of OHE and MHE patients admitted to fatigue after actual driving on the AMA survey compared with no MHE patients (P=0.02). All patients who admitted to fatigue and none who denied fatigue on the AMA survey had simulator collisions. Psychometric and simulator performance in treated OHE patients was similarly impaired to MHE patients despite therapy. Within groups, a significant increase in collisions, speeding, and center crossings in the second half (P=0.01) was seen only in MHE patients.

CONCLUSIONS

Psychometric and simulator performance in patients with recent OHE on treatment is similarly impaired as that of untreated MHE patients. Simulator performance in MHE worsens over time with fatigue. OHE and MHE patients had a higher rate of actual driving-associated fatigue on the AMA survey, which was significantly predictive of simulator collisions.

Receptive language outcomes in children after cochlear implantation

OBJECTIVES

The objectives of the present study were (1) to assess receptive language scores in children after cochlear implantation and compare them with scores in normal hearing children and children with hearing loss that use hearing aids and (2) to determine how demographic factors, such as age of implantation, impact language outcomes.

STUDY DESIGN

Case series.

SUBJECTS/METHODS

Receptive language scores in children with profound prelingual hearing loss who received cochlear implants between 1996 and 2004 were analyzed.

RESULTS

Standardized language assessments were available for 36 children. The average age at implantation was 33 months. The mean language scores for implanted children were within 1 standard deviation of scores of normal hearing individuals. Children with cochlear implants had significantly higher subtest scores (P < 0.05) than children with hearing aids. Children with additional disabilities had significantly (P < 0.05) poorer language performance.

CONCLUSIONS

Pediatric cochlear implant recipients acquire receptive language skills that approach those of their hearing peers and exceed those of children with hearing aids.

Mouth care in nursing homes: knowledge, beliefs, and practices of nursing assistants

The purpose of this study was to examine the knowledge, beliefs, and practices of nursing assistants (NAs) providing oral hygiene care to frail elders in nursing homes, with the intent of developing an educational program for NAs.

METHODS

The study occurred in two economically and geographically diverse nursing homes. From a sample size of 202 NAs, 106 returned the 19-item Oral Care Survey.

RESULTS

The NAs reported satisfactory knowledge regarding the tasks associated with providing mouth care. The NAs believed that tooth loss was a natural consequence of aging. They reported that they provided mouth care less frequently than is optimal but cited challenges such as caring for persons exhibiting care-resistive behaviors, fear of causing pain, and lack of supplies.

CONCLUSION

Nurses are in a powerful position to support NAs in providing mouth care by ensuring that they have adequate supplies and knowledge to respond to resistive behaviors.

Comparison of lesion sizes produced by cryoablation and open irrigation radiofrequency ablation catheters

INTRODUCTION

The relative lesion sizes created by large electrode cryoablation catheter and irrigated radiofrequency (RF) ablation are not known. The purpose of this study was to directly compare lesion sizes created by cryoablation and irrigated RF under controlled conditions.

METHODS AND RESULTS

Ablation lesions were created in freshly harvested porcine left ventricular myocardium in a blood-filled tissue bath using an 8-mm-tip cryoablation catheter and a 3.5-mm-tip open-irrigated RF ablation catheter. Lesions were created under all permutations of the following conditions: electrode orientation vertical (perpendicular) or horizontal (parallel) to the tissue, electrode contact pressure at 6 or 20 g, and blood flow at 0.2 or 0.4 m/s over the electrode-tissue interface. The largest lesion volumes created with cryoablation were 961 +/- 103 mm(3), compared with the largest lesions volumes created with RF of 680 +/- 48 mm(3) (P < 0.001). The 3-way interactions among electrode orientation, contact pressure, and superfusate blood velocity accounted for the variation in lesion volumes for both catheters (both r(2)= 0.97, both P < 0.0001). The greater contact pressure increased lesion size for both cryoablation and RF. For cryoablation, lesion sizes were increased by the horizontal orientation and by the lower blood flow velocity. For open-irrigated RF, lesion sizes were significantly reduced by the horizontal orientation, however.

CONCLUSIONS

Depending on conditions of electrode orientation, contact pressure, and blood velocity, either 8-mm-tip cryoablation or open-irrigated RF may produce the larger lesion volumes. Open-irrigated RF lesion sizes are reduced in the horizontal catheter orientation.

Time to Electrode Rewarming After Cryoablation Predicts Lesion Size

INTRODUCTION

There are no methods in clinical use to assess tissue cooling during catheter cryoablation. Cryoablation electrode temperature may be a poor predictor of lesion size. The purpose of this study was to determine whether the time necessary for the cryoablation electrode to cool to target temperature or to rewarm after cryoablation can predict lesion size.

METHODS AND RESULTS

Cryoablation was performed on live porcine left ventricle in a saline bath (37 degrees C) using 8-mm-tip catheter. Cryoablation was given for 300 seconds under all permutations of the following conditions: electrode orientation vertical or horizontal, contact pressure 6 or 20 g, superfusate flow over electrode-tissue interface at 0.2 or 0.4 m/s (N = 10 each condition set, total 80 experiments). The time intervals necessary to cool the electrode to the target temperature of -75 degrees C and to rewarm to + 30 degrees C after termination of cryoablation were recorded. Lesion volume was predicted best by the time necessary to rewarm the electrode to +30 degrees C (r2 = 0.65, P < 0.0001), followed by electrode temperature (r2 = 0.28, P < 0.0001) and time to cool the electrode to -75 degrees C (r2 = 0.24, P < 0.0001). Time to +30 degrees C and time to -75 degrees C were associated with superfusate flow rate, contact pressure, and electrode orientation (r2 = 0.80 and 0.61, respectively, both P < 0.0001). Superfusate flow rate, contact pressure, and orientation were also highly predictive of lesion volume (r2 = 0.93, P < 0.0001).

CONCLUSIONS

Time to cryoablation electrode rewarming is a better predictor of cryoablation lesion size than is electrode temperature. Time to cryoablation electrode rewarming reflects important determinants of cryoablation lesion formation--convective warming, contact pressure, and electrode orientation--that are not ascertainable during clinical ablation procedures.

Determinants of lesion sizes and tissue temperatures during catheter cryoablation

BACKGROUND

Factors which influence lesion size from catheter-based cryoablation have not been well described. This study describes factors which influence lesion size during catheter cryoablation.

METHODS AND RESULTS

Cryoablation was delivered to porcine left ventricular myocardium in a saline bath using 4- or 8-mm electrode catheters. Ablation was delivered with the electrodes either vertical or horizontal to the tissue and both with and without superfusate flow over the electrode. The effect of electrode contact pressure was tested. Lesion dimensions were measured. All experiments were duplicated to measure tissue temperatures at 1-, 2-, 3-, and 5-mm deep to the ablation electrode. The 8-mm electrode produced lower tissue temperatures and larger lesion volumes when compared with the 4-mm electrode (all P < 0.05). Superfusate flow slowed the rate of tissue cooling, markedly warmed tissue temperatures, and reduced lesion volume when compared with no flow conditions. By linear regression modeling, lesion sizes and tissue temperatures were related to the presence of superfusate flow, electrode orientation, contact pressure and electrode size, or catheter refrigerant flow rate (r2 for models = 0.90-0.96, all P < 0.001). Electrode temperature predicted lesion size or tissue temperatures only when analyzed independent of electrode size or refrigerant flow rate.

CONCLUSIONS

Lesion sizes and tissue temperatures during catheter cryoablation are related to convective warming, electrode orientation, electrode contact pressure, and any of the following: electrode size, catheter refrigerant flow rate or electrode temperature. However, electrode temperature may be a poor predictor of lesion size and tissue temperature for a given catheter size.

A review of body water status and the effects of age and body fatness in children and adults

BACKGROUND

Most investigations of TBW, ECW and body composition and reports of their intra-body relationships were published prior to 1980. Distributional TBW and ECW relationships within the body have been considered fixed, but there was evidence these relationships were affected by the level of fatness. Body composition models based on past findings and assumptions could produce inaccurate estimates when the majority of the population is overweight to obese.

METHODS

TBW and ECW volumes, their proportions of body weight, FFM and percent body fat and associations with age are considered in U.S. children and adults. This review focuses on studies reporting measured body water volumes from large samples except for the national predicted values from NHANES III.

RESULTS

Measured TBW volumes for children and adults are almost exclusively from whites with the exception of the estimated values from NHANES III for non-Hispanic black and Mexican-Americans. Mean adult TBW volumes are as much as 9 liters greater than those reported prior to 1980. Low mean percentages of TBW%WT reflect the greater level of adiposity in children and adults, and this level of adiposity affects the value of TBW% FFM. Mean ECW volumes for white adults are 10 to 12 liters larger than those reported previously. With greater fatness in adults, ECW%TBW has increased to near 60%, and this implies that a calculation of FFM based on 73% and an ECW%TBW of 25-45% could produce an overestimation but more important clinically an underestimation of body fatness.

CONCLUSION

There is inadequate timely information on measured total and extra-cellular water volumes for the population. Available data indicate a coincident increase in body water with overweight and obesity, and a shifting in the proportion of ECW in TBW. Clinical and pharmacological treatments based upon past assumptions of body water volumes, proportions and relationships could produce inaccurate estimates.

Lipids, lipoproteins, lifestyle, adiposity and fat-free mass during middle age: the Fels Longitudinal Study

INTRODUCTION

Although lipid profiles tend to worsen with age, it is not fully known if such age-related changes are influenced primarily by body composition and lifestyle or by other aspects of aging.

OBJECTIVE

We investigated the extent to which the fat and fat-free components of body mass index (BMI) and lifestyle factors influence patterns of change in lipids independent of age.

DESIGN

Serial data were analyzed using sex-specific longitudinal models. These models use serial data from individuals to assume a general pattern of change over time, while allowing baseline age and the rate of change to vary among individuals.

SUBJECTS

Serial data were obtained from 940 examinations of 269 healthy white participants (126 men, 143 women), aged 40-60 years, in the Fels Longitudinal Study.

MEASUREMENTS

Measurements included age, the fat (FMI) and fat-free mass (FFMI) components of BMI, high-density lipoprotein (HDL-C), low-density lipoprotein (LDL-C), triglycerides (TG), total cholesterol (TC), fasting glucose and insulin, physical activity, alcohol use and smoking, and women's menopausal status and estrogen use.

RESULTS

In both sexes, increased FMI was significantly associated with increased LDL-C, TG and TC, and decreased HDL-C. Increased FFMI was significantly related to decreased HDL-C and increased TG. Independent age effects remained significant only for LDL-C and TC in men and TC in women. Increased insulin was significantly related to increased TG in women. Moderate alcohol consumption was associated with higher HDL-C in men. Physical activity lowered male LDL-C and TC levels, and increased female HDL-C levels. Menopause was associated with increases in LDL-C. Premenopausal women not using estrogen had significantly lower HDL-C, TG, and TC than postmenopausal women taking estrogen.

CONCLUSIONS

(1) Age is an important independent predictor for LDL-C and TC in men, and TC in women, but it is not as influential as body composition and lifestyle on HDL-C and TG in men and women, and LDL-C in women. (2) Increasing FMI is the major contributor to elevated TC, LDL-C and TG levels, and decreased HDL-C levels in men and women. (3) FFMI significantly influences HDL and TG levels in both sexes. (4) Maintaining a lower BMI via a reduced fat component may be more beneficial in lowering CVD risks than other factors.

Effects of Gap Geometry on Conduction Through Discontinuous Radiofrequency Lesions

Background— Gaps of sufficient cross-sectional dimensions within linear radiofrequency (RF) lesions may allow conduction through the lesion. The purpose of this study was to examine the effects of different gap geometries on conduction through discontinuous RF lesions.

Methods and Results— Radiofrequency lesions were created in isolated, perfused rabbit right ventricular (RV) free wall preparations to produce gaps with 3 different lesion geometries: straight, bifurcated, and angled (n=10 each group). Angled preparations contained 2 right angles within the conduction path. Optical mapping was used to assess bidirectional conduction through the myocardium before and after gap formation during pacing at 1000-, 400-, and 200-ms cycle lengths. Histological analysis was performed on each preparation after optical mapping. After lesion formation, 9 of 10 straight gap preparations and 1 of 10 angled gap preparations demonstrated bidirectional conduction ( P <0.001) at all cycle lengths. Nine of 10 bifurcated gap preparations demonstrated bidirectional conduction and 1 demonstrated unidirectional conduction at all cycle lengths. Two bifurcated gap preparations showed rate-dependent unidirectional 2:1 conduction. All unidirectional and rate-dependent block occurred during impulse propagation in the direction of diverging arms of the bifurcation. The occurrence of bidirectional conduction in the gaps was associated with the gap geometry ( P <0.0001). Histological analysis confirmed the continuity of viable myocardium transmurally throughout the length of the gap in each preparation. The sites of conduction block were demonstrated to be just after the first angle in the conduction path for angled gaps and at the branch point of a bifurcated gap. The predominant myofiber orientation was changed relative to the conduction path at angulations of the gaps. Flecainide (0.1 μmol/L) produced bidirectional conduction block in straight and bifurcated gap preparations with bidirectional conduction at baseline.

Conclusions— Conduction through discontinuities in RF lesions is associated with gap geometry. Complex gap geometry may allow for unidirectional and/or rate-dependent block. Gaps within RF lesions are susceptible to pharmacological blockade.

Do changes in body mass index percentile reflect changes in body composition in children? Data from the Fels Longitudinal Study

OBJECTIVE

Our aim was to examine the degree to which changes in BMI percentile reflect changes in body fat and lean body mass during childhood and how age and gender affect these relationships.

METHODS

This analysis used serial data on 494 white boys and girls who were aged 8 to 18 years and participating in the Fels Longitudinal Study (total 2319 observations). Total body fat (TBF), total body fat-free mass (FFM), and percentage of body fat (%BF) were determined by hydrodensitometry, and then BMI was partitioned into its fat and fat-free components: fat mass index (FMI) and FFM index (FFMI). We calculated predicted changes (Delta) in FMI, FFMI, and %BF for each 10-unit increase in BMI percentile using mixed-effects models.

RESULTS

FFMI had a linear relationship with BMI percentile, whereas FMI and %BF tended to increase dramatically only at higher BMI percentiles. Gender and age had significant effects on the relationship between BMI percentile and FFMI, FMI, and %BF. Predicted Delta%BF for boys 13 to 18 years of age was negative, suggesting loss of relative fatness for each 10-unit increase in BMI percentile.

CONCLUSIONS

In this longitudinal study of white children, FFMI consistently increased with BMI percentile, whereas FMI and %BF had more complicated relationships with BMI percentile depending on gender, age, and whether BMI percentile was high or low. Our results suggest that BMI percentile changes may not accurately reflect changes in adiposity in children over time, particularly among male adolescents and children of lower BMI.

Total body water volume for white children and adolescents and anthropometric prediction equations: the Fels Longitudinal Study

BACKGROUND

There are few studies of total body water (TBW) volume in children. Such studies are needed, as are new prediction equations for the clinical management of children with renal insufficiency and those receiving dialysis.

METHODS

Mixed longitudinal data were from 124 white boys and 116 white girls 8 to 20 years of age. TBW volume was measured by deuterium nuclear magnetic resonance spectroscopy, and random effects models were used to determine patterns of change over time. Sex-specific TBW prediction equations were developed using regression analysis.

RESULTS

Boys had significantly greater (P < 0.05) mean TBW volumes than girls at all but 3 ages. TBW was significantly (P < 0.05) associated with age and maturation in the boys and the girls. In boys, mean TBW/WT varied from 0.55 to 0.59, while in the girls the mean declined from 0.53 to 0.49 by 16 years of age. Boys had significantly larger means for TBW/WT than girls, who had a significant, slight negative trend with age. The prediction equations were TBW = -25.87 + 0.23 (stature) + 0.37 (weight) for boys and TBW =-14.77 + 0.18 (stature) + 0.25 (weight) for girls.

CONCLUSION

Means are provided for TBW in white children from 8 to 20 years of age, whose average fatness affected the percentage of TBW in body weight. These updated TBW prediction equations perform better than those available from the past.

Concordant and discordant sexual maturation among U.S. children in relation to body weight and BMI

PURPOSE

This study investigates the extent to which discordant Tanner stages for sexual maturity indicators are associated with weight and body mass index (BMI) and their variation during adolescence. Discordant children with large differences in weight and BMI may require additional monitoring of their growth during adolescence.

METHODS

Weight, BMI and Tanner stages, pubic hair in each gender, breast development in girls and genital development in boys, from 2103 boys and 2104 girls aged 8-18 years (average age 13.34 years) from the National Health and Nutrition Examination Survey III (NHANES III, 1988-1994) were analyzed. These cross-sectional data were grouped as concordant: assessed stages for paired indicators were equivalent, or as discordant: assessed stage for one paired indicator was greater or less than the other by one or more stages. Weight and BMI were compared separately by gender and race between concordant and discordant groups using analysis of covariance adjusted for age.

RESULTS

Approximately 65-69% of all children were concordant, genital stage equaled pubic hair stage for boys and breast stage equaled pubic hair stage for girls. For all three racial groups, boys whose genital stage was more advanced than their pubic hair stage had significantly smaller weight and BMI (p<.05) than either concordant boys or boys whose pubic hair stage was more advanced than their genital stage. For all three racial groups, girls whose breast stage was more advanced than their pubic hair stage had significantly greater weight and BMI than girls whose pubic hair stage was more advanced than breast stage. Non-Hispanic black and Mexican-American girls whose breast stage was more advanced than their pubic hair stage had significantly greater weight and BMI that the respective concordant girls.

CONCLUSION

Substantial and significant differences occur in weight and BMI among discordant and concordant children, and these differences are larger than between early and late maturing children.

Is sexual maturity occurring earlier among U.S. children?

PURPOSE

To compare the onset and completion of sexual maturation among U.S. children between 1966 and 1994.

METHODS

Tanner stages were from 3042 non-Hispanic white boys, 478 black boys, 2625 white girls, and 505 black girls (NHES 1966-70), from 717 Mexican-American boys and 712 Mexican-American girls (HHANES 1982-84) and from 259 non-Hispanic white boys, 411 black boys, 291 white girls, 415 black girls, 576 Mexican-American boys and 512 Mexican-American girls (NHANES III 1988-1994). Proportions of entry into a stage, probit analysis estimated medians and selected percentiles for ages at entry were calculated using SUDAAN.

RESULTS

NHANES III (1988-1994) non-Hispanic white boys entered stage 2, 3, and 4 genital development and stages 3 and 4 pubic hair earlier than NHES (1966-1970) white boys, but they entered stage 5 genital development significantly later. NHANES III (1988-1994) Mexican-American boys were in stage 2, 3 and 4 genital development earlier than HHANES (1982-1984) boys, but entry into stage 5 genital and pubic hair development was not significant. NHANES III (1988-1994) white girls entered stage 5 pubic hair later than NHES (1966-1970) white girls. NHANES III (1988-1994) Mexican-American girls entered stage 2 breast and pubic hair development earlier than HHANES (1982-1984) girls, entered stage 4 breast and pubic hair development earlier but entered stage 5 pubic hair later than the HHANES (1982-1984) girls.

CONCLUSION

Persuasive evidence of a secular trend toward early maturation is not found between 1966 and 1994 in non-Hispanic black boys and non-Hispanic black and white girls. Some evidence of this trend is found in non-Hispanic white boys between 1966 and 1994 and in Mexican-American boys and girls between 1982 and 1994.