Intraoperative Evaluation of Breast Tissues During Breast Cancer Operations Using the MasSpec Pen

Importance

Surgery with complete tumor resection remains the main treatment option for patients with breast cancer. Yet, current technologies are limited in providing accurate assessment of breast tissue in vivo, warranting development of new technologies for surgical guidance.

Objective

To evaluate the performance of the MasSpec Pen for accurate intraoperative assessment of breast tissues and surgical margins based on metabolic and lipid information.

Design, Setting, and Participants

In this diagnostic study conducted between February 23, 2017, and August 19, 2021, the mass spectrometry-based device was used to analyze healthy breast and invasive ductal carcinoma (IDC) banked tissue samples from adult patients undergoing breast surgery for ductal carcinomas or nonmalignant conditions. Fresh-frozen tissue samples and touch imprints were analyzed in a laboratory. Intraoperative in vivo and ex vivo breast tissue analyses were performed by surgical staff in operating rooms (ORs) within 2 different hospitals at the Texas Medical Center. Molecular data were used to build statistical classifiers.

Main Outcomes and Measures

Prediction results of tissue analyses from classification models were compared with gross assessment, frozen section analysis, and/or final postoperative pathology to assess accuracy.

Results

All data acquired from the 143 banked tissue samples, including 79 healthy breast and 64 IDC tissues, were included in the statistical analysis. Data presented rich molecular profiles of healthy and IDC banked tissue samples, with significant changes in relative abundances observed for several metabolic species. Statistical classifiers yielded accuracies of 95.6%, 95.5%, and 90.6% for training, validation, and independent test sets, respectively. A total of 25 participants enrolled in the clinical, intraoperative study; all were female, and the median age was 58 years (IQR, 44-66 years). Intraoperative testing of the technology was successfully performed by surgical staff during 25 breast operations. Of 273 intraoperative analyses performed during 25 surgical cases, 147 analyses from 22 cases were subjected to statistical classification. Testing of the classifiers on 147 intraoperative mass spectra yielded 95.9% agreement with postoperative pathology results.

Conclusions and Relevance

The findings of this diagnostic study suggest that the mass spectrometry-based system could be clinically valuable to surgeons and patients by enabling fast molecular-based intraoperative assessment of in vivo and ex vivo breast tissue samples and surgical margins.

Intraoperative Identification of Thyroid and Parathyroid Tissues During Human Endocrine Surgery Using the MasSpec Pen

Importance

Intraoperative identification of tissues through gross inspection during thyroid and parathyroid surgery is challenging yet essential for preserving healthy tissue and improving outcomes for patients.

Objective

To evaluate the performance and clinical applicability of the MasSpec Pen (MSPen) technology for discriminating thyroid, parathyroid, and lymph node tissues intraoperatively.

Design, Setting, and Participants

In this diagnostic/prognostic study, the MSPen was used to analyze 184 fresh-frozen thyroid, parathyroid, and lymph node tissues in the laboratory and translated to the operating room to enable in vivo and ex vivo tissue analysis by endocrine surgeons in 102 patients undergoing thyroidectomy and parathyroidectomy procedures. This diagnostic study was conducted between August 2017 and March 2020. Fresh-frozen tissues were analyzed in a laboratory. Clinical analyses occurred in an operating room at an academic medical center. Of the analyses performed on 184 fresh-frozen tissues, 131 were included based on sufficient signal and postanalysis pathologic diagnosis. From clinical tests, 102 patients undergoing surgery were included. A total of 1015 intraoperative analyses were performed, with 269 analyses subject to statistical classification. Statistical classifiers for discriminating thyroid, parathyroid, and lymph node tissues were generated using training sets comprising both laboratory and intraoperative data and evaluated on an independent test set of intraoperative data. Data were analyzed from July to December 2022.

Main Outcomes and Measures

Accuracy for each tissue type was measured for classification models discriminating thyroid, parathyroid, and lymph node tissues using MSPen data compared to gross analysis and final pathology results.

Results

Of the 102 patients in the intraoperative study, 80 were female (78%) and the median (IQR) age was 52 (42-66) years. For discriminating thyroid and parathyroid tissues, an overall accuracy, defined as agreement with pathology, of 92.4% (95% CI, 87.7-95.4) was achieved using MSPen data, with 82.6% (95% CI, 76.5-87.4) accuracy achieved for the independent test set. For distinguishing thyroid from lymph node and parathyroid from lymph node, overall training set accuracies of 97.5% (95% CI, 92.8-99.1) and 96.1% (95% CI, 91.2-98.3), respectively, were achieved.

Conclusions and Relevance

In this study, the MSPen showed high performance for discriminating thyroid, parathyroid, and lymph node tissues intraoperatively, suggesting this technology may be useful for providing near real-time feedback on tissue type to aid in surgical decision-making.

Aggregated Molecular Phenotype Scores: Enhancing Assessment and Visualization of Mass Spectrometry Imaging Data for Tissue-Based Diagnostics

Mass spectrometry imaging (MSI) has gained increasing popularity for tissue-based diagnostics due to its ability to identify and visualize molecular characteristics unique to different phenotypes within heterogeneous samples. Data from MSI experiments are often assessed and visualized using various supervised and unsupervised statistical approaches. However, these approaches tend to fall short in identifying and concisely visualizing subtle, phenotype-relevant molecular changes. To address these shortcomings, we developed aggregated molecular phenotype (AMP) scores. AMP scores are generated using an ensemble machine learning approach to first select features differentiating phenotypes, weight the features using logistic regression, and combine the weights and feature abundances. AMP scores are then scaled between 0 and 1, with lower values generally corresponding to class 1 phenotypes (typically control) and higher scores relating to class 2 phenotypes. AMP scores, therefore, allow the evaluation of multiple features simultaneously and showcase the degree to which these features correlate with various phenotypes. Due to the ensembled approach, AMP scores are able to overcome limitations associated with individual models, leading to high diagnostic accuracy and interpretability. Here, AMP score performance was evaluated using metabolomic data collected from desorption electrospray ionization MSI. Initial comparisons of cancerous human tissues to their normal or benign counterparts illustrated that AMP scores distinguished phenotypes with high accuracy, sensitivity, and specificity. Furthermore, when combined with spatial coordinates, AMP scores allow visualization of tissue sections in one map with distinguished phenotypic borders, highlighting their diagnostic utility.

Advances and Emerging Medical Applications of Direct Mass Spectrometry Technologies for Tissue Analysis

Offering superb speed, chemical specificity, and analytical sensitivity, direct mass spectrometry (MS) technologies are highly amenable for the molecular analysis of complex tissues to aid in disease characterization and help identify new diagnostic, prognostic, and predictive markers. By enabling detection of clinically actionable molecular profiles from tissues and cells, direct MS technologies have the potential to guide treatment decisions and transform sample analysis within clinical workflows. In this review, we highlight recent health-related developments and applications of direct MS technologies that exhibit tangible potential to accelerate clinical research and disease diagnosis, including oncological and neurodegenerative diseases and microbial infections. We focus primarily on applications that employ direct MS technologies for tissue analysis, including MS imaging technologies to map spatial distributions of molecules in situ as well as handheld devices for rapid in vivo and ex vivo tissue analysis.

Utilizing Aggregated Molecular Phenotype (AMP) Scores to Visualize Simultaneous Molecular Changes in Mass Spectrometry Imaging Data

Mass spectrometry imaging (MSI) has gained increasing popularity for tissue-based diagnostics due to its ability to identify and visualize molecular characteristics unique to different phenotypes within heterogeneous samples. Data from MSI experiments are often visualized using single ion images and further analyzed using machine learning and multivariate statistics to identify m/z features of interest and create predictive models for phenotypic classification. However, often only a single molecule or m/z feature is visualized per ion image, and mainly categorical classifications are provided from the predictive models. As an alternative approach, we developed an aggregated molecular phenotype (AMP) scoring system. AMP scores are generated using an ensemble machine learning approach to first select features differentiating phenotypes, weight the features using logistic regression, and combine the weights and feature abundances. AMP scores are then scaled between 0 and 1, with lower values generally corresponding to class 1 phenotypes (typically control) and higher scores relating to class 2 phenotypes. AMP scores therefore allow the evaluation of multiple features simultaneously and showcase the degree to which these features correlate with various phenotypes, leading to high diagnostic accuracy and interpretability of predictive models. Here, AMP score performance was evaluated using metabolomic data collected from desorption electrospray ionization (DESI) MSI. Initial comparisons of cancerous human tissues to normal or benign counterparts illustrated that AMP scores distinguished phenotypes with high accuracy, sensitivity, and specificity. Furthermore, when combined with spatial coordinates, AMP scores allow visualization of tissue sections in one map with distinguished phenotypic borders, highlighting their diagnostic utility.

Long-chain polyunsaturated lipids associated with responsiveness to anti-PD-1 therapy are colocalized with immune infiltrates in the tumor microenvironment

The programmed cell death protein-1 (PD-1) is highly expressed on the surface of antigen-specific exhausted T cells and, upon interaction with its ligand PD-L1, can result in inhibition of the immune response. Anti-PD-1 treatment has been shown to extend survival and result in durable responses in several cancers, yet only a subset of patients benefit from this therapy. Despite the implication of metabolic alteration following cancer immunotherapy, mechanistic associations between antitumor responses and metabolic changes remain unclear. Here, we used desorption electrospray ionization mass spectrometry imaging to examine the lipid profiles of tumor tissue from three syngeneic murine models with varying treatment sensitivity at the baseline and at three time points post-anti-PD-1 therapy. These imaging experiments revealed specific alterations in the lipid profiles associated with the degree of response to treatment and allowed us to identify a significant increase of long-chain polyunsaturated lipids within responsive tumors following anti-PD-1 therapy. Immunofluorescence imaging of tumor tissues also demonstrated that the altered lipid profile associated with treatment response is localized to dense regions of tumor immune infiltrates. Overall, these results indicate that effective anti-PD-1 therapy modulates lipid metabolism in tumor immune infiltrates, and we thereby propose that further investigation of the related immune-metabolic pathways may be useful for better understanding success and failure of anti-PD-1 therapy.

Clinical Translation and Evaluation of a Handheld and Biocompatible Mass Spectrometry Probe for Surgical Use

BACKGROUND

Intraoperative tissue analysis and identification are critical to guide surgical procedures and improve patient outcomes. Here, we describe the clinical translation and evaluation of the MasSpec Pen technology for molecular analysis of in vivo and freshly excised tissues in the operating room (OR).

METHODS

An Orbitrap mass spectrometer equipped with a MasSpec Pen interface was installed in an OR. A "dual-path" MasSpec Pen interface was designed and programmed for the clinical studies with 2 parallel systems that facilitated the operation of the MasSpec Pen. The MasSpec Pen devices were autoclaved before each surgical procedure and were used by surgeons and surgical staff during 100 surgeries over a 12-month period.

RESULTS

Detection of mass spectral profiles from 715 in vivo and ex vivo analyses performed on thyroid, parathyroid, lymph node, breast, pancreatic, and bile duct tissues during parathyroidectomies, thyroidectomies, breast, and pancreatic neoplasia surgeries was achieved. The MasSpec Pen enabled gentle extraction and sensitive detection of various molecular species including small metabolites and lipids using a droplet of sterile water without causing apparent tissue damage. Notably, effective molecular analysis was achieved while no limitations to sequential histologic tissue analysis were identified and no device-related complications were reported for any of the patients.

CONCLUSIONS

This study shows that the MasSpec Pen system can be successfully incorporated into the OR, allowing direct detection of rich molecular profiles from tissues with a seconds-long turnaround time that could be used to inform surgical and clinical decisions without disrupting tissue analysis workflows.

Abstract 624: Clinical evaluation of the MasSpec Pen technology for rapid diagnosis and margin assessment in pancreatic cancer surgery

Precise removal of pancreatic ductal adenocarcinoma (PDAC) with microscopically negative margins, commonly assessed by frozen section analysis, is associated with longer disease-free survival. However, histologic complexities and tissue-processing artifacts can render frozen section analysis of PDAC margins a challenging and time-consuming task, with reported accuracies dependent on the skillset and subspecialty of the pathologist on call. We developed the MasSpec Pen, a handheld device coupled to a mass spectrometer, for rapid (~15 s) and nondestructive molecular analysis and diagnosis of tissues. The MasSpec Pen supplies a discrete water droplet onto a tissue's surface, allowing diagnostic metabolites and lipids to be extracted into the droplet and then transmitted into a mass spectrometer for analysis. Here, we evaluate the performance of the MasSpec Pen for intraoperative diagnosis of PDAC in human pancreatic and bile duct margins. Pancreatic and bile duct tissue samples (N=157) were obtained from the Cooperative Human Tissue Network and Baylor College of Medicine and stored at -80°C prior to analysis. A Q Exactive mass spectrometer (Thermo Scientific) coupled to the MasSpec Pen was used for analysis of thawed samples in the negative ion mode. Tissues were then cryo-sectioned, H&E stained, and blindly evaluated by a pathologist. Based on the distinct molecular profiles acquired, we generated two statistical classifiers using lasso penalized logistic regression for distinguishing PDAC from healthy pancreas and bile duct tissue based on a sparse set of molecular features indicative of disease state. For distinguishing normal pancreas from PDAC, an overall accuracy of 91.5%, sensitivity of 95.5%, and specificity of 89.7% was achieved for training, validation, and test sets. Classification results for discriminating normal bile duct from PDAC had an overall accuracy of 95%, sensitivity of 92%, and specificity of 100% in training and validation. We have begun clinical testing of the MasSpec Pen in human surgeries following its successful translation to an operating room at Texas Medical Center. To date, the MasSpec Pen has been used to analyze in vivo and fresh ex vivo tissue in 19 pancreatic surgeries. When predicting on 64 intraoperative analyses using classification models built on banked data, 93.8% agreement with final postoperative pathology reports was achieved. While further validation studies are needed, our results show that the MasSpec Pen can distinguish PDAC from normal pancreas and bile duct tissues with high accuracy and is compatible for in vivo use, suggesting this technology may be valuable for near real-time margin evaluation during pancreatic oncologic surgeries.

Citation Format: Mary E. King, Jialing Zhang, John Q. Lin, Kyana Y. Garza, Rachel J. DeHoog, Clara L. Feider, Alena V. Bensussan, Marta Sans, Anna Krieger, Sunil Badal, Michael F. Keating, Sadhna Dhingra, Wendong Yu, George Van Buren, Christopher Pirko, Kirtan Brahmbhatt, William E. Fisher, James W. Suliburk, Livia S. Eberlin. Clinical evaluation of the MasSpec Pen technology for rapid diagnosis and margin assessment in pancreatic cancer surgery [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 624.

The Utility of Frozen Section Histology in Diagnosing Periprosthetic Joint Infection in Revision Total Joint Arthroplasty

BACKGROUND

Surgeons utilize a combination of preoperative tests and intraoperative findings to diagnose periprosthetic joint infection (PJI); however, there is currently no reliable diagnostic marker that can be used in isolation. The purpose of our study is to evaluate the utility of frozen section histology in diagnosis of PJI.

METHODS

Retrospective analysis of 614 patients undergoing revision total joint arthroplasty with frozen section histology from a single institution was performed. Discriminatory value of frozen section histology was assessed using univariate analysis and evaluation of area under the curve (AUC) of a receiver operating characteristic curve comparing frozen section histology results to the 2018 International Consensus Meeting (ICM) PJI criteria modified to exclude the histology component.

RESULTS

The sensitivity of the frozen section histology was 53.6% and the specificity was 95.2%. There was 99.2% concordance between the permanent section and frozen section results. The receiver operating characteristic curve for frozen section yielded an AUC of 0.744 (95% confidence interval 0.627-0.860) and the modified ICM score yielded an AUC of 0.912 (95% confidence interval 0.836-0.988) when compared to the full score. The addition of frozen section histology changed the decision to infected in 20% of "inconclusive" cases but less than 1% of total cases.

CONCLUSION

In comparison to the modified ICM criteria, intraoperative frozen section histology has poor sensitivity, strong specificity, and acceptable overall discrimination for diagnosing PJI. This test appears to be of particular value for patients deemed "inconclusive" for infection using the remaining ICM criteria.

Gq-activated fibroblasts induce cardiomyocyte action potential prolongation and automaticity in a three-dimensional microtissue environment

Cardiac fibroblasts (CFs) are known to regulate cardiomyocyte (CM) function in vivo and in two-dimensional in vitro cultures. This study examined the effect of CF activation on the regulation of CM electrical activity in a three-dimensional (3-D) microtissue environment. Using a scaffold-free 3-D platform with interspersed neonatal rat ventricular CMs and CFs, G_q-mediated signaling was selectively enhanced in CFs by Gα_q adenoviral infection before coseeding with CMs in nonadhesive hydrogels. After 3 days, the microtissues were analyzed by signaling assay, histological staining, quantitative PCR, Western blots, optical mapping with voltage- or Ca²⁺-sensitive dyes, and microelectrode recordings of CF resting membrane potential (RMP_CF). Enhanced G_q signaling in CFs increased microtissue size and profibrotic and prohypertrophic markers. Expression of constitutively active Gα_q in CFs prolonged CM action potential duration (by 33%) and rise time (by 31%), prolonged Ca²⁺ transient duration (by 98%) and rise time (by 65%), and caused abnormal electrical activity based on depolarization-induced automaticity. Constitutive G_q activation in CFs also depolarized RMP_CF from -33 to -20 mV and increased connexin 43 and connexin 45 expression. Computational modeling confers that elevated RMP_CF and increased cell-cell coupling between CMs and CFs in a 3-D environment could lead to automaticity. In conclusion, our data demonstrate that CF activation alone is capable of altering action potential and Ca²⁺ transient characteristics of CMs, leading to proarrhythmic electrical activity. Our results also emphasize the importance of a 3-D environment where cell-cell interactions are prevalent, underscoring that CF activation in 3-D tissue plays a significant role in modulating CM electrophysiology and arrhythmias.NEW & NOTEWORTHY In a three-dimensional microtissue model, which lowers baseline activation of cardiac fibroblasts but enables cell-cell, paracrine, and cell-extracellular matrix interactions, we demonstrate that selective cardiac fibroblast activation by enhanced G_q signaling, a pathophysiological trigger in the diseased heart, modulates cardiomyocyte electrical activity, leading to proarrhythmogenic automaticity.

Functional scaffold-free 3-D cardiac microtissues: a novel model for the investigation of heart cells

To bridge the gap between two-dimensional cell culture and tissue, various three-dimensional (3-D) cell culture approaches have been developed for the investigation of cardiac myocytes (CMs) and cardiac fibroblasts (CFs). However, several limitations still exist. This study was designed to develop a cardiac 3-D culture model with a scaffold-free technology that can easily and inexpensively generate large numbers of microtissues with cellular distribution and functional behavior similar to cardiac tissue. Using micromolded nonadhesive agarose hydrogels containing 822 concave recesses (800 μm deep × 400 μm wide), we demonstrated that neonatal rat ventricular CMs and CFs alone or in combination self-assembled into viable (Live/Dead stain) spherical-shaped microtissues. Importantly, when seeded simultaneously or sequentially, CMs and CFs self-sorted to be interspersed, reminiscent of their myocardial distribution, as shown by cell type-specific CellTracker or antibody labeling. Microelectrode recordings and optical mapping revealed characteristic triangular action potentials (APs) with a resting membrane potential of -66 ± 7 mV (n = 4) in spontaneously contracting CM microtissues. Under pacing, optically mapped AP duration at 90% repolarization and conduction velocity were 100 ± 30 ms and 18.0 ± 1.9 cm/s, respectively (n = 5 each). The presence of CFs led to a twofold AP prolongation in heterogenous microtissues (CM-to-CF ratio of 1:1). Importantly, Ba(2+)-sensitive inward rectifier K(+) currents and Ca(2+)-handling proteins, including sarco(endo)plasmic reticulum Ca(2+)-ATPase 2a, were detected in CM-containing microtissues. Furthermore, cell type-specific adenoviral gene transfer was achieved, with no impact on microtissue formation or cell viability. In conclusion, we developed a novel scaffold-free cardiac 3-D culture model with several advancements for the investigation of CM and CF function and cross-regulation.

Social mobility and reproduction among nineteenth-century Colorado silver prospectors

Popular cultural convention holds that, for those with enough gumption, the American frontier was a land of unparalleled opportunity. However, careful research throws doubt on the universality of this convention. Thus, the authors explore factors that increase or decrease opportunities for upward mobility in frontier towns. The authors' longitudinal study of late nineteenth century silver prospectors in Gothic, Colorado, demonstrates that while enthusiastic prospecting in Gothic did not lead to upward social mobility, it did provide enhanced reproductive opportunities.

Whole abdominal radiotherapy in the adjuvant treatment of patients with stage III and IV endometrial cancer: a gynecologic oncology group study

OBJECTIVE

To evaluate toxicity, survival, and recurrence-free interval in women with loco-regionally advanced endometrial carcinoma treated with postoperative whole abdominal radiation therapy.

METHODS

Whole abdominal irradiation with pelvic plus or minus para-aortic boost was initiated within 8 weeks of total abdominal hysterectomy, bilateral salpingo-oophorectomy, pelvic washings, and selective pelvic and para-aortic node sampling in eligible, consenting patients.

RESULTS

Of 180 evaluable patients entered on the study with surgically staged III and IV endometrial carcinoma maximally debulked to less than 2 cm, 77 had typical endometrial adenocarcinoma and 103 had high-risk histology, either papillary serous or clear cell carcinoma. Patients with typical endometrial adenocarcinoma were significantly younger and had significantly fewer poorly differentiated cancers. Proportionally, there were twice as many non-Whites with high-risk histologies as non-Whites with typical endometrial adenocarcinoma. Forty-five percent of patients with typical endometrial adenocarcinomas had positive pelvic nodes compared to 51% of those with high-risk histologies. Both histologic groups had similar distribution for performance status, para-aortic node positivity, site and extent of disease, and International Federation of Gynecology and Obstetrics (FIGO) stage. The frequency of severe or life-threatening adverse effects among 174 patients evaluable for radiation toxicity included 12.6% with bone marrow depression, 15% GI, and 2.2% hepatic toxicity. The recurrence-free survival rates were 29% and 27% (at 3 years) for the typical endometrial adenocarcinoma and high-risk histologies, respectively. The survival rates were 31% and 35%, respectively. No patient with gross residual disease survived.

CONCLUSION

Whole abdominal irradiation in maximally resected advanced endometrial carcinoma has tolerable toxicity, and it is suggested that the outcome may be improved by this adjunctive treatment in patients with completely resected disease.

Lambing rates and litter sizes following intrauterine or cervical insemination of frozen/thawed semen with or without oxytocin administration

Intrauterine insemination by laparoscopy is required to achieve acceptable lambing rates in ewes when using frozen semen but the procedure has evoked welfare concerns. Oxytocin has been used to dilate the cervix as a means of accessing the uterus during conventional cervical insemination, but its effect on fertility is not well documented. Three hundred crossbred ewes were synchronised in estrus and randomly allocated to one of three insemination procedures using frozen/thawed semen containing 400 x 10(6)/ml progressively motile sperm: single cervical (0.2 ml), multiple cervical (4 x 0.05 ml) or laparoscopic (0.05 ml per uterine horn). The effects of each insemination procedure on lambing rate (percentage of treated ewes lambing) and litter size (lambs per ewe lambing) were tested with and without oxytocin (10 IU given i.m.) prior to fixed-time insemination. Oxytocin did not permit complete cervical penetration in any ewes and neither lambing rate nor litter size was influenced by the number of inseminations. Lambing percentages were 69 and 42 (P < 0.01) for the laparoscopic and cervical insemination methods, respectively, and oxytocin reduced these to 58 (NS) and 10 (P < 0.001) percent, respectively. Corresponding litter sizes for ewes not receiving oxytocin were 1.91 and 1.51 and for those receiving oxytocin, 1.83 and 1.41 (laparoscopic versus cervical, P < 0.02). Thus, in the absence of complete cervical penetration at insemination, 10 IU oxytocin decreased the number of ewes lambing but had no effect on their litter size.

Risk factors for asthma incidence. A review of recent prospective evidence

AIM

The aim of this study is to determine what factors have been shown, in prospective studies, to predict the incidence of asthma.

METHODS

We performed a systematic review of peer-reviewed literature from 1994 to 2004 to determine what factors predict the development of asthma in both children and adults. This search strategy yielded 40 studies, with 36 providing some estimate of asthma incidence for the total sample and or a specific subgroup.

RESULTS

Annual estimated incidence of physician-diagnosed asthma ranged from 0.6 to 29.5 per 1000 persons. Risk factors for incident asthma among children included: male sex, atopic sensitization, parental history of asthma, early-life stressors and infections, obesity, and exposure to indoor allergens, tobacco smoke and outdoor pollutants. Risk factors for adult-onset asthma included female sex, airway hyperresponsiveness, lifestyle factors, and work-related exposures.

CONCLUSION

Risk factors for asthma include both modifiable and nonmodifiable ones, and they vary between children and adults. This review of prospective evidence supports tobacco and smoke avoidance as an intervention for the primary prevention of childhood asthma. During adolescence and adulthood, targeting lifestyle factors like obesity and smoking or reducing occupational exposures are the best opportunities for asthma prevention. Before specific public health recommendations can be made, however, additional longitudinal research is needed to better characterize target populations and identify appropriate settings for multifaceted asthma interventions.

Effect of diet and GnRH administration on post-partum ovarian cyclicity in autumn-lambing ewes

Using autumn-lambing ewes, this study investigated (i) the effects of diet on gonadotrophin secretion and responsiveness of the hypothalamic-pituitary-ovarian axis to exogenous GnRH during the early post-partum period; and (ii) whether ovulation prior to completion of uterine involution results in an increased incidence of aberrant ovarian cycles. Thirty-two ewes rearing 1.9+/-0.12 lambs were equally allocated to two dietary treatments at lambing (22 October +/-0.2 day). Diets comprised ad libitum hay and 1.5 kg per ewe per day of one of two concentrates (11.5 MJ ME, 195 g CP per kg) containing 300 g kg(-1) cracked maize grain (M) or 300 g kg(-1) sugar beet pellets (S). Half of the ewes on each diet (G) received 25 i.v. injections of 250 ng GnRH in 2 ml 0.9% saline at 2 h intervals from days 12-14 post-partum while remaining ewes (N) were monitored for the resumption of spontaneous ovarian cyclicity. Blood samples were obtained from all ewes throughout the study (lambing to 18 December) for measurement of circulating hormone concentrations and the uteri and ovaries of all ewes were examined via laparoscopy on day 21 post-partum. There were no effects of dietary treatment on ewe daily live weight loss, lamb daily live weight gain or the immediate post-partum increase in circulating FSH concentrations. Diet did not affect insulin concentrations or LH pulse frequency on day 12 post-partum but LH pulse amplitude was lower in ewes fed concentrate M compared to concentrate S (1.4+/-0.10 versus 1.7+/-0.12 ng ml(-1), respectively, P<0.05) and this was associated with an increased interval to the resumption of spontaneous ovarian cycles (35+/-3.1 versus 26+/-2.1 day, respectively, P<0.05). Administration of exogenous GnRH increased (P<0.05) the proportion of ewes on both diets that ovulated within 20 days of parturition and advanced the onset of ovarian cyclicity in ewes fed concentrate M by 9.5 days (significance of interaction, P<0.05). Four ewes, all of which ovulated before day 22 post-partum, had extended luteal activity while in remaining ewes, duration of the first luteal phase was inversely related to the time of first ovulation (r(2)=0.16, P<0.05). Results demonstrate that (i) the onset of ovarian cyclicity is influenced by diet and can be advanced by administration of exogenous GnRH; and (ii) ovulation during the early post-partum period is associated with an increased incidence of extended luteal activity.

Interleukin 8 in the cervix of non-pregnant ewes

Studies of cervical artificial insemination of ewes at hormone-synchronized oestrus indicate that the cervix remains relatively impenetrable to semen, in contrast to naturally breeding animals. During parturition the inflammatory response plays an important part in cervical dilation and possibly, to a lesser extent, in the non-pregnant cervix at oestrus to facilitate the transcervical transport of semen. The expression of interleukin 8 (IL-8), a pro-inflammatory cytokine in the ovine cervix, has been mapped and quantified, using semi-quantitative in situ hybridization, to ascertain the role played by inflammation in the ovine cervix during natural and artificially induced oestrous cycles. IL-8 gene expression was observed in both the luminal epithelium and fibroblastic cells of the cervix. The presence of IL-8 was confirmed using immunohistochemistry. IL-8 gene expression in the luminal epithelium varied throughout the oestrous cycle and was highest at oestrus and at day 5 of the oestrous cycle. In ewes artificially induced to ovulate, either by the withdrawal of progesterone pessaries after treatment for 12 days, or by two i.m. injections of prostaglandin 9 days apart, IL-8 gene expression at oestrus was significantly lower than it was at natural oestrus. Insemination increased IL-8 gene expression in progesterone-synchronized ewes. These data support the hypothesis that IL-8-induced inflammation is important in normal cervical function and that this process is inhibited during artificial synchronization of the oestrous cycle and is increased by exposure to semen.

Interleukin 8 in the cervix of non-pregnant ewes

Studies of cervical artificial insemination of ewes at hormone-synchronized oestrus indicate that the cervix remains relatively impenetrable to semen, in contrast to naturally breeding animals. During parturition the inflammatory response plays an important part in cervical dilation and possibly, to a lesser extent, in the non-pregnant cervix at oestrus to facilitate the transcervical transport of semen. The expression of interleukin 8 (IL-8), a pro-inflammatory cytokine in the ovine cervix, has been mapped and quantified, using semi-quantitative in situ hybridization, to ascertain the role played by inflammation in the ovine cervix during natural and artificially induced oestrous cycles. IL-8 gene expression was observed in both the luminal epithelium and fibroblastic cells of the cervix. The presence of IL-8 was confirmed using immunohistochemistry. IL-8 gene expression in the luminal epithelium varied throughout the oestrous cycle and was highest at oestrus and at day 5 of the oestrous cycle. In ewes artificially induced to ovulate, either by the withdrawal of progesterone pessaries after treatment for 12 days, or by two i.m. injections of prostaglandin 9 days apart, IL-8 gene expression at oestrus was significantly lower than it was at natural oestrus. Insemination increased IL-8 gene expression in progesterone-synchronized ewes. These data support the hypothesis that IL-8-induced inflammation is important in normal cervical function and that this process is inhibited during artificial synchronization of the oestrous cycle and is increased by exposure to semen.

Clinical applications of wall-stress analysis in the pediatric intensive care unit

OBJECTIVE

To determine whether serial, noninvasive assessment of afterload, contractility, and Doppler-derived cardiac output reliably detects variations in cardiac function in unstable pediatric patients.

DESIGN

Prospective, blinded clinical trial.

SETTING

The pediatric intensive care unit at Massachusetts General Hospital.

PATIENTS

Fourteen critically ill pediatric patients.

INTERVENTIONS

Pediatric patients meeting criteria for hemodynamic instability underwent serial echocardiograms every 6 hrs until they met exit criteria, generating 75 studies.

MEASUREMENTS AND MAIN RESULTS

Shortening fraction, cardiac index (CI), end-systolic wall stress (ESWS), and corrected velocity of circumferential shortening (Vcfc) were measured in each patient. Data points were plotted as a stress-velocity relationship, compared with published normal values, then correlated with changes in vital signs and pharmacologic interventions. Fourteen of 16 patients who were enrolled completed the study. A strong negative correlation between ESWS and Vcfc was confirmed (p < .001). As an internal measure of validity, Vcfc had a strong positive correlation with CI measurements (p = .012). An increase in dopamine infusion was associated with a fall in ESWS (p = .02), an increase in Vcfc (p = .03), and an increase in the CI as measured by Doppler (p = .035). The infusion of dopamine above renal perfusion levels moved patients from zones of normal or compensated contractility for afterload on a modified stress-velocity relationship to a zone of high contractility for afterload. Urine output was the only clinical index of cardiac function that had a significant correlation with the echocardiographic indices. Hemodynamically unstable patients followed similar patterns of deterioration and recovery on the modified stress-velocity graph. All surviving patients returned to a normal or compensated zone.

CONCLUSIONS

Wall-stress analysis of cardiac function is easily and safely performed on mechanically ventilated pediatric patients with the production of consistently high-quality data. For internal validity, Vcfc and CI measurements were correlated and were strongly positive. Wall-stress indices reliably detected patient deterioration, recovery, and response to changes in dopamine infusion. Patients who failed to return to areas of normal or compensated levels of contractility and afterload did poorly in this study. Noninvasive measures of afterload and contractility appear useful for monitoring cardiac function of critically ill children in an intensive care setting.

Exercise reduces daily fatigue in women with breast cancer receiving chemotherapy

PURPOSE

Cancer treatment-related fatigue is the most prevalent and distressing symptom of cancer therapy. Interventions to minimize fatigue are needed. The purpose of this study was to examine the relationship between exercise and fatigue over the first three cycles of chemotherapy in women receiving either cyclophosphamide, methotrexate, and fluorouracil (CMF) or doxorubicin and cyclophosphamide (AC) for breast cancer.

METHODS

Seventy-two newly diagnosed women with breast cancer were instructed in a home-based moderate-intensity exercise intervention. Measures of functional ability, energy expenditure, and fatigue were obtained at baseline and posttest. Subjects maintained daily records of four types of fatigue, and exercise duration, intensity, and type.

RESULTS

Exercise significantly reduced all four levels of fatigue (P < 0.01). As the duration of exercise increased, the intensity of fatigue declined (P < 0.01). There was a significant carry-over effect of exercise on fatigue, but the effect lasted only 1 d. The level of fatigue at study entry was not associated with number of days of exercise or amount of exercise a woman engaged in.

CONCLUSIONS

The impact of exercise on fatigue was significant and suggests the effectiveness of a low- to moderate-intensity regular exercise program in maintaining functional ability and reducing fatigue in women with breast cancer receiving chemotherapy.

Structural analysis of Pick's disease-derived and in vitro-assembled tau filaments

Pick's and Alzheimer's diseases are distinct neurodegenerative disorders both characterized in part by the presence of intracellular filamentous tau protein inclusions. The tight bundles of paired helical filaments (PHFs) of tau protein found in Alzheimer's disease (AD) differ from the tau filaments of Pick's disease in their morphology, distribution, and pathological structure as identified by silver impregnation. The filaments of Pick's disease are loosely arranged in pathognomonic spherical inclusions found in ballooned neurons, whereas the tau pathology of AD is classically described as a triad of neuropil threads, neurofibrillary tangles, and dystrophic neurites surrounding and invading plaques. In this study we used the high-resolution technique of scanning transmission electron microscopy to characterize and compare the filaments found in Pick's disease with those found in AD. In addition, we determined the mass/nm length and density of arachidonic acid-induced in vitro-assembled filaments. Three morphologically distinct populations of Pick's filaments were identified but each was indistinguishable from AD-PHFs in mass/nm length and density. Filaments assembled in vitro from single isoforms were similar in mass/nm length, but less dense than AD-PHFs and Pick's disease filaments. Finally, we provide clear structural evidence that a PHF, whether found in disease or assembled in vitro, is composed of two distinct intertwined filaments.

Concept, development, administration, and analysis of a certifying examination in echocardiography for physicians

In 1993, the American Society of Echocardiography appointed a committee to develop an objective examination in echocardiography. In 1995, a pilot of this examination was administered, with operational examinations offered each year from 1996 to 1999. This report describes the development of the examination, including its underlying philosophy, the test itself, and the scoring process, and includes results from the first 4 examinations. To date, 1266 physicians have taken the examination, and roughly 60% of those have passed. The number of echocardiograms performed or interpreted each week had the largest effect on examination scores; the effects of both the amount of training and the practice discipline were small but significant. The evolution of the original committee and new directions for the testing organization are also discussed.

Oxidative regulation of fatty acid-induced tau polymerization

Alzheimer's disease (AD) is characterized by the presence of amyloid-positive senile plaques and tau-positive neurofibrillary tangles. Aside from these two pathological hallmarks, a growing body of evidence indicates that the amount of oxidative alteration of vulnerable molecules such as proteins, DNA, and fatty acids is elevated in the brains of AD patients. It has been hypothesized that the elevated amounts of protein oxidation could lead directly to the formation of neurofibrillary tangles through a cysteine-dependent mechanism. We have tested this hypothesis in an in vitro system in which tau assembly is induced by fatty acids. Using sulfhydryl protective agents and site-directed mutagenesis, we found that cysteine-dependent oxidation of the tau molecule is not required for its polymerization and may even be inhibitory. However, by adjusting the oxidative environment of the polymerization reaction through the addition of a strong antioxidant or through the addition of an oxidizing system consisting of iron, adenosine diphosphate, and ascorbate, we found that oxidation does play a major role in our in vitro paradigm. The results indicated that fatty acid oxidation, the amount of which is found to be elevated in AD patients, can facilitate the polymerization of tau. However, "overoxidation" of the fatty acids can inhibit the process. Therefore, we postulate that specific fatty acid oxidative products could provide a direct link between oxidative stress mechanisms and the formation of neurofibrillary tangles in AD.

In vitro polymerization of tau protein monitored by laser light scattering: method and application to the study of FTDP-17 mutants

Tau polymerization into the filaments that compose neurofibrillary tangles is seminal to the development of many neurodegenerative diseases. It is therefore important to understand the mechanisms involved in this process. However, a consensus method for monitoring tau polymerization in vitro has been lacking. Here we demonstrate that illuminating tau polymerization reactions with laser light and measuring the increased scattering at 90 degrees to the incident beam with a digital camera results in data that closely approximate the mass of tau polymer formation in vitro. The validity of the technique was demonstrated over a range of tau concentrations and through multiple angle scattering measurements. In addition, laser light scattering data closely correlated with quantitative electron microscopy measurements of the mass of tau filaments. Laser light scattering was then used to measure the efficiency with which the mutant tau proteins found in frontotemporal dementia and Parkinsonism linked to chromosome 17 (FTDP-17) form filamentous structures. Several of these mutant proteins display enhanced polymerization in the presence of arachidonic acid, suggesting a direct role for these mutations in tau the filament formation that characterizes FTDP-17.

Differential assembly of human tau isoforms in the presence of arachidonic acid

Six tau isoforms arise from the alternative splicing of a single gene in humans. Insoluble, filamentous deposits of tau protein occur in a number of neurodegenerative diseases, and in some of these diseases, the deposition of polymers enriched in certain tau isoforms has been documented. Because of these findings, we have undertaken studies on the efficacy of fatty acid-induced polymerization of the individual tau isoforms found in the adult human CNS. The polymerization of each tau isoform in the presence of two concentrations of arachidonic acid indicated that isoforms lacking N-terminal exons e2 and e3 formed small, globular oligomers that did not go on to elongate into straight (SF) or paired helical (PHF) filaments under our buffer conditions. The polymerization of all isoforms containing e2 or e2 and e3 occurred readily at a high arachidonic acid concentration. Conversely, at a lower arachidonic acid concentration, only tau isoforms containing four microtubule binding repeats assembled well. Under all buffer conditions employed, filaments formed from three of the isoforms containing e2 and e3 resembled SFs in morphology but began to form PHF-like structures following extended incubation at 37 degrees C. These results indicate that polymerization of the intact tau molecule may be facilitated by e2 and e3. Moreover, tau isoforms containing three versus four microtubule binding repeats display different assembly properties depending on the solvent conditions employed.

Closure of patent foramen ovale for paradoxical emboli: intermediate-term risk of recurrent neurological events following transcatheter device placement

OBJECTIVES

We report the largest and the longest follow-up to date of patients who underwent transcatheter patent foramen ovale (PFO) closure for paradoxical embolism.

BACKGROUND

Closure of a PFO has been proposed as an alternative to anticoagulation in patients with presumed paradoxical emboli.

METHODS

Data were collected for patients following PFO closure with the Clamshell, CardioSEAL or Buttoned Devices at two institutions.

RESULTS

There were 63 patients (46 +/- 18 years) with a follow-up of 2.6 +/- 2.4 years. Fifty-four (86%) had effective closure of the foramen ovale (trivial or no residual shunt by echocardiography) while seven (11%) had mild and two (3%) had moderate residual shunting. There were four deaths (leukemia, pulmonary embolism, sepsis following a hip fracture and lung cancer). There were four recurrent embolic neurological events following device placement: one stroke and three transient events. The stroke occurred in a 56-year-old patient six months following device placement. A follow-up transesophageal echocardiogram showed a well seated device without residual shunting. Two of the four events were associated with suboptimal device performance (one patient had a significant residual shunt and a second patient had a "friction lesion" in the left atrial wall associated with a displaced fractured device arm). The risk of recurrent stroke or transient neurological event following device placement was 3.2% per year for all patients.

CONCLUSION

Transcatheter closure of PFO is an alternative therapy for paradoxical emboli in selected patients. Improved device performance may reduce the risk of recurrent neurological events. Further studies are needed to identify patients most likely to benefit from this intervention.

Fatigue patterns observed in patients receiving chemotherapy and radiotherapy

The purpose of this study was to describe the patterns of cancer-related fatigue (CRF) and vigor in patients receiving chemotherapy or radiation therapy. Five studies that measured fatigue and vigor with the Profile of Mood States were used to describe the pattern of CRF and vigor during and after both types of treatment. Repeated-measures ANOVA was used to determine differences over time in each study. Results demonstrate different patterns of CRF for patients receiving chemotherapy and radiation therapy. Chemotherapy-related CRF peaks in the days after chemotherapy, whereas radiation therapy-related CRF gradually accumulates over the course of treatment. The CRF associated with both forms of treatment gradually declines over time. The prevalence, intensity, and persistence of CRF during treatment and for months after treatment is complete make this symptom one that cannot be ignored.

Ligand-dependent tau filament formation: implications for Alzheimer's disease progression

The mechanism through which arachidonic acid induces the polymerization of tau protein into filaments under reducing conditions was characterized through a combination of fluorescence spectroscopy and electron microscopy. Results show that polymerization follows a ligand-mediated mechanism, where binding of arachidonic acid is an obligate step preceding tau-tau interaction. Homopolymerization begins with rapid (on the order of seconds) nucleation, followed by a slower elongation phase (on the order of hours). Although essentially all synthetic filaments have straight morphology at early time points, they interact with thioflavin-S and monoclonal antibody Alz50 much like authentic paired helical filaments, suggesting that the conformation of tau protein is similar in the two filament forms. Over a period of days, synthetic straight filaments gradually adopt paired helical morphology. These results define a novel pathway of tau filament formation under reducing conditions, where oxidation may contribute to final paired helical morphology, but is not a necessary prerequisite for efficient nucleation or elongation of tau filaments.

Tissue adhesives: a new method of wound repair

Simple traumatic lacerations are one of the most common reasons for visits to the emergency department. Traditionally, wound repair has been performed using sutures. The use of tissue adhesives is an approved and popular alternative method of wound closure in several countries. Numerous published studies have found that, with appropriate use, repair of lacerations using tissue adhesives is faster, less painful, and more economical than suturing. Tissue adhesives result in fewer wound infections than suturing, and cosmetic outcomes have been comparable to or better than suturing. The newest product, 2-octylcyanoacrylate, received Food and Drug Administration approval in 1998 and is being marketed in the United States. The technique of wound repair with tissue adhesives is easily mastered and is a useful skill in the management of simple lacerations. This article provides a comprehensive review of the literature on the use of tissue adhesives and discusses them as an alternative to traditional methods of wound repair.

Ovulation, fertilization and lambing rates, and peripheral progesterone concentrations, in ewes inseminated at a natural oestrus during November or February

The objective of this study was to determine the relative importance of seasonal changes in ovulation rate, fertilization rate and embryo survival as the cause of reduced lambing rates in ewes mated in February compared with those mated in November. The study was conducted at 57 degrees N using mature Mule ewes and Suffolk rams. Sixty ewes were allocated equally to five groups: unbred (UB) or mated at a natural oestrus during November (N) or February (F) by natural (N) or cervical artificial (A) insemination. Groups were maintained separately at pasture supplemented with hay. A raddled vasectomized or non-vasectomized ram was present with UB, NN and NA groups from 26 October 1995 to 1 January 1996 and with UB, FN and FA groups from 25 January 1996 to 31 March 1996. Ewes marked by the ram were recorded twice a day, and those in groups NN, NA, FN and FA were inseminated at their second behavioural oestrus. For all ewes, blood samples were obtained once a day from introduction of the vasectomized rams until 30 days after mating (groups NN, NA, FN and FA) or 20 days after the first oestrus (group UB), and ovulation rate was measured by laparoscopy 7 days after the first oestrus. For ewes in groups NN, NA, FN and FA, ovulation rate was measured again after the second oestrus and ova were recovered from six ewes per group for assessment of fertilization before autotransfer. Pregnancy and lambing rates were recorded at term. Mean (+/- SE) dates of the first recorded oestrus for ewes in groups NN, NA and UB, and FN, FA and UB were 4 +/- 1.1 November and 4 +/- 0.9 February, respectively, and intervals between the first and second oestrus were 16 +/- 0.2 and 17 +/- 0.3 days (P < 0.01), respectively. Ovulation rates were 2.6 +/- 0.08 and 2.0 +/- 0.05 (P < 0.001), and peripheral progesterone concentrations during the luteal phase were 8.5 +/- 0.25 and 7.6 +/- 0.31 ng ml-1 (P < 0.05), for November and February, respectively. The difference in peripheral progesterone concentration was not solely attributable to the difference in ovulation rate. There was no significant effect of month or method of insemination, or of embryo recovery and autotransfer procedures on pregnancy rates and the proportion of ewes that became pregnant were NN 0.92, NA 0.83, FN 0.67 and FA 0.75. For ewes undergoing embryo recovery and autotransfer, ova recovered per corpus luteum were 1.00, 0.93, 1.00 and 0.92, fertilized ova per ovum recovered were 0.69, 0.92, 1.00 and 0.83, and lambs born per corpus luteum were 0.62, 0.79, 0.78 and 0.58 for NN, NA, FN and FA groups, respectively. There were no significant seasonal effects on fertilization rate or embryo survival. It is concluded that a seasonal decline in ovulation rate is the primary cause of reduced lambing rates in ewes mated in February compared with those mated in November. Pregnancy rates were high after mating in both periods and were not enhanced by the use of cervical insemination.

Planning and conducting a multi-institutional project on fatigue

PURPOSE/OBJECTIVES

To describe the process used in proposal development and study implementation for a complex multisite project on cancer treatment-related fatigue (CRF), identify strategies used to manage the project, and provide recommendations for teams planning multisite research.

DATA SOURCES

Information derived from project team meeting records, correspondence, proposals, and personal recollection.

DATA SYNTHESIS

The project was built on preexisting relationships among the three site investigators who then built a team including faculty, research coordinators, staff nurses, and students. Study sites had a range of organizational models, and the proposal was designed to capitalize on the organizational and resource strengths of each setting. Three team members drawn from outside oncology nursing provided expertise in measurement and experience with fatigue in other populations. Planning meetings were critical to the success of the project. Conference calls, fax technology, and electronic mail were used for communication. Flexibility was important in managing crises and shifting responsibility for specific components of the work. The team documented and evaluated the process used for multisite research, completed a major instrumentation study, and developed a cognitive-behavioral intervention for CRF.

CONCLUSIONS

Accomplishments during the one-year planning grant exceeded initial expectations. The process of conducting multisite research is complex, especially when the starting point is a planning grant with specific research protocols to be developed and implemented over one year. Explicit planning for decision-making processes to be used throughout the project, acknowledging the differences among the study settings and planning the protocols to capitalize upon those differences, and recruiting a strong research team that included a member with planning grant and team-building expertise were essential elements for success.

IMPLICATIONS FOR NURSING PRACTICE

Specific recommendations for others planning multisite research are related to team-building, team membership, communication, behavioral norms, role flexibility, resources, feedback, problem management, and shared recognition.

Relationship between % heart rate reserve and % VO2 reserve in treadmill exercise

For exercise prescription purposes, it is often assumed that % heart rate reserve (%HRR) provides equivalent intensities to %VO2max. However, a recent study from this laboratory demonstrated that during cycling exercise %HRR is not equivalent to %VO2max, but is instead equivalent to a percentage of the difference between resting and maximal VO2, i.e., % VO2reserve (%VO2R). The current study examined these relationships during treadmill exercise. Fifty adults performed Bruce protocol treadmill tests to exhaustion. For each subject, data obtained at rest, at the end of each stage, and at maximum were used to determine linear regressions of %HRR versus %VO2max, and of %HRR versus %VO2R. For %HRR versus %VO2max the mean intercept and slope were -6.1+/-0.7 and 1.10+/-0.01, respectively, with a mean r of 0.990+/-0.002. For %HRR versus %VO2R, the mean intercept and slope were 1.5+/-0.6 and 1.03+/-0.01, respectively, with a mean r of 0.990+/-0.002. Both regressions differed statistically from the line of identity (i.e., intercept of 0 and slope of 1). However, the regression of %HRR versus %VO2R was significantly closer (P < 0.001 ) to the line of identity than was the regression of %HRR versus %VO2max. We conclude that %HRR should be considered as an indicator of %VO2R, not %VO2max, when prescribing treadmill exercise, as was previously concluded for cycling exercise.

Two-dimensional echocardiographic assessment of the progression of aortic root size in 127 patients with chronic aortic regurgitation: role of the supraaortic ridge and relation to the progression of the lesion

Although aortic root dilation has etiologic and prognostic significance in patients with chronic aortic regurgitation (AR), no information is available regarding changes over time in aortic root size in patients with the entire spectrum of AR severity or how such changes relate to progression of the AR or to left ventricular (LV) overload. To analyze this, a total of 127 patients with chronic AR who had more than 6 months of follow-up by two-dimensional and Doppler echocardiography were included in the study (69 men and 58 women; mean age 59.3 +/- 21.2 years [range 14 to 94 years]; 67 cases of mild, 45 moderate, 15 severe, and 21 bicuspid aortic valve disease). The aortic anulus, sinuses of Valsalva, supraaortic ridge, and ascending aorta were measured in the parasternal long-axis view, LV volumes were calculated (biplane Simpson's approach), and the severity of AR was quantified based on proximal jet size and graded according to an algorithm that takes into account major color Doppler criteria. At entry to the study, significant differences between patients with mild, moderate, and severe AR were noted only in supraaortic ridge size (1.46 +/- 0.29 cm/m2 vs 1.63 +/- 0.33 cm/m2 [p < 0.006]; vs 1.67 +/- 0.43 cm/m2 [p < 0.03]). A significant increase in aortic root size at all levels was observed during the follow-up period in all three groups of severity of AR. The rate of change of the supraaortic ridge, the upper support structure of the anulus and cusps, was faster in patients with more severe degrees of AR (p = 0.013); this was not the case at the other aortic levels. No differences were observed in aortic root size or rate of progression between patients with bicuspid or tricuspid aortic valves. Patients were considered "progressive" if they lay on the steepest positive segment of the curve representing the rank order in the rate of aortic root progression. Compared with "nonprogressive" patients, patients who were progressive in supraaortic ridge size (rate >0.12 cm/yr; n = 23) had a faster rate of progression in the degree of regurgitation as assessed by the regurgitant jet area/LV outflow tract area ratio measured in the parasternal short-axis view (0.48 +/- 0.45 vs 0.24 +/- 0.5/yr; p < 0.03) and a foster rate of progression of LV end-diastolic volume (30 +/- 22.8 vs 14.4 +/- 15.6 ml/yr; p < 0.0002) and LV mass (70.8 +/- 74.4 vs 16.8 +/- 19.2 gm/yr; p < 0.0004). In conclusion, there is progressive dilation of the aortic root at all levels, even in patients with mild AR. More rapid progression in aortic root size is associated with more rapid progression of the underlying aortic insufficiency, as well as more rapid increases in LV volume and mass.

Quantitative assessment of stenotic aortic valve area by using intracardiac echocardiography: in vitro validation and initial in vivo illustration

Quantitative assessment of aortic stenosis (AS) is subject to the limitations of all current noninvasive and invasive methods. The ability to obtain a direct measure of aortic valve area with high resolution by intracardiac echocardiography (ICE) could be of great benefit to catheterized patients. To provide a fixed AS area as an ideal standard for comparison, we performed ICE in 12 sheep hearts with experimentally created AS and five human AS hearts from autopsies. ICE catheters were passed retrograde across the aortic valve, and the minimal orifice area on pullback was planimetered and compared with calibrated video imaging. The entire orifice circumference could be successfully recorded in 16 (94%) hearts. Orifice area from ICE correlated well with actual values (r=0.98; standard error of the estimate [SEE] = 0.06 cm2). To illustrate the applicability in vivo, two canine models and 10 patients with AS were studied. The limiting orifice could be imaged in both animals and in 8 of 10 patients, in whom values agreed well with invasive data (r= 0.95; SEE = 0.04 cm2). ICE can therefore accurately measure AS orifice area in vitro; it can be applied in vivo as well. These validation studies laid the foundation for subsequent clinical studies and applications.

Apparent versus real exposures of nuclear medicine technologists during aerosol lung ventilation scanning

The exposure of nuclear medicine technologists to airborne radiocontaminants is generally far below the compliance limits. Most of the contamination is external rather than internal deposition. Higher contamination levels approaching the allowable limits are rare. Personal respiratory protection is unwarranted and may have undesirable impressions on patients undergoing lung scanning. Exposures are well controlled by suitable work practices that are in keeping with as low as reasonably achievable (ALARA) principles.

Use of epidemiologic principles to identify risk factors associated with the development of diarrhea in calves in five beef herds

The objective of the study reported here was to identify and measure risk factors associated with the incidence of diarrhea in calves in 5 beef herds in North Dakota. Risk factors associated with calves developing diarrhea during the 1992 calving season were used to develop the following intervention strategies that were implemented during 1993: heifers calved in a separate location, diarrheal calves and their dams were placed in a quarantine area, and pregnant cattle were fed a diet supplemented with protein and copper. The risk of calves developing diarrhea was 5 times higher during the first year, compared with the second year, suggesting that the management changes made during the second year were contributing factors in reducing the percentage of calves with diarrhea. The risk of diarrhea developing in calves born to heifers was 3.9 times greater than that in calves born to cows. Analysis of our data indicated that the use of an epidemiologic approach can identify risk factors, which can lead to the development of intervention procedures that may decrease the incidence of diarrhea in calves in beef herds.

Intracardiac ultrasonographic assessment of atrial septal defect area: in vitro validation and technical considerations

Assessment of atrial septal defect (ASD) size and shape is important for planning and guiding its transcatheter occlusion and can potentially be achieved by intracardiac ultrasonography (ICUS). ICUS accuracy, however, must first be established against stable standards and technical imaging requirements defined. We therefore used 10, 20, and 30 MHz ICUS catheters to examine 17 ASDs that were 0.16 to 6.7 cm2 in area and were surgically created in excised ovine hearts with 10, 20, and 30 MHz ICUS catheters. ASD shape and area by ICUS were compared with direct video images of the actual ASD. In all instances minimal area by ICUS pullback agreed well with actual values (y = 1.04x + 0.2, SEE = 0.23 cm2, r = 0.99) and corresponded well with defect shapes. The maximum angle between ultrasonography beam and septal plane allowing for complete ASD visualization was 20 degrees. The angle depended on transducer frequency and septal thickness. This new technique has potential value for the accurate assessment of ASD shape and size and may be especially useful in the setting of transcatheter occlusion.

Prenatal ultrasonographic diagnosis of ductus arteriosus aneurysm with spontaneous neonatal closure

Aneurysm of the ductus arteriosus may be either spontaneous or acquired as a complication of surgical closure of a patent duct. Patients may be asymptomatic or present with a wide spectrum of symptoms, including hoarseness, respiratory symptoms, aortic or pulmonary thrombosis or embolism, or rupture of the aneurysm. We present the first report of prenatal ultrasonographic diagnosis of isolated ductus arteriosus aneurysm. The aneurysm presented at 39 weeks as an enlarged, dilated, vascular structure 15 mm in diameter, which began at the bifurcation of the main pulmonary artery and ended in the descending aorta. Doppler imaging demonstrated turbulent flow in this lesion. Following spontaneous delivery, a bidirectional shunt in the ductus arteriosus was found on the 1st day, but the caliber of the vessel was normal. An almost completely functionally closed ductus was found on the 2nd day. Spontaneous resolution of the lesion was confirmed by magnetic resonance imaging at 4 weeks of age.

Differences in particle deposition between the two lungs

Certain inhalational diseases show a predilection for a particular region of one or the other lung that may be related to the site of deposition of inhaled particles. We conducted inhalation studies with monodispersed aerosol particles in 22 healthy student volunteers to determine how deposition varied between the two lungs. Ventilation lung scans were obtained with the subjects seated in front of a gamma camera while breathing radiolabelled particles. Subsequently we made paired comparisons of the radioactivity deposited in corresponding regions of the right and left lungs. Although regional differences in deposition between the left and right lung were often statistically significant, they were not always consistent between individuals. Particle deposition and the degree of penetration differed between the two lungs with there being generally more deposition in the perihilar region of the right lung. We suggest that the anatomy of the central airways may influence the pattern of deposition, thereby introducing disparities in particle deposition between the two lungs. The present findings lend support to experimental lung cast data and to the concept that anatomical differences between the two lungs influence the site of deposition.

Comparison of two MGA-PGF2α systems for synchronization of estrus in beef heifers

Yearling beef heifers (n=193) were used to evaluate reproductive performance attained with 2 MGA-PGF2alpha synchronization systems. These treatments were compared with an untreated control group. The 14-d MGA heifers were synchronized by feeding 0.5 mg MGA/h/d for 14 d. At 17 d after the last MGA feeding, these heifers were injected with PGF2alpha (25 mg, im). Heifers in the 7-d MGA treatment group were fed 0.5 mg MGA/h/d for 7 d and received a 25-mg, im injection of PGF2alpha on the last day of the MGA feeding period. Heifers in all 3 treatment groups were observed for estrus every 12 h for 7 d beginning 24 h after the PGF2alpha injection. Heifers observed in estrus during this 7-d period were artificially inseminated approximately 12 h after the onset of estrus. The percentages of heifers in estrus during the 7-d synchronized period were 75.4, 56.3 and 17.2% for the 14-d MGA, 7-d MGA and control groups, respectively. The estrous responses were significantly different in each treatment. The percentage of heifers in estrus during the peak 24-h period was higher (P<0.05) in heifers synchronized with the 14-d MGA system than in heifers synchronized with the 7-d MGA system (75.5 vs 50.0%). The synchronized conception rate of the 14-d MGA heifers was significantly higher (65.3%) than that of both the 7-d MGA (41.7%) and control (45.4%) heifers. Synchronized conception rates were similar (P=0.79) in the 7-d MGA and control treatments. Synchronized pregnancy rates were 55.2, 32.4 and 15.2% for the 14-d MGA, 7-d MGA and control groups, respectively. Both synchronization treatments resulted in significantly higher synchronized pregnancy rates compared with that of the controls. The synchronized pregnancy rate was higher (P<0.05) in the 14-d MGA group than it was in the 7-d MGA group. The mean day of conception within the breeding season was 11.5 and 9.3 d shorter in the 14-d MGA heifers than in the 7-d MGA and control heifers, respectively. Our results indicate that using the 14-d MGA system to synchronize estrus in beef heifers results in better reproductive performance than that attained in heifers synchronized with the 7-d MGA system or in control heifers.