Evaluation of a Best-Practice Advisory for Primary Aldosteronism Screening

Importance

Primary aldosteronism (PA) is a common cause of secondary hypertension and an independent risk factor for cardiovascular morbidity and mortality. Fewer than 2% to 4% of patients at risk are evaluated for PA.

Objective

To develop and evaluate an electronic health record best-practice advisory (BPA) that assists with PA screening.

Design, Setting, and Participants

This prospective quality improvement study was conducted at academic center outpatient clinics. Data analysis was performed between February and June 2023 and included adults with hypertension and at least 1 of the following: 4 or more current antihypertensive medications; hypokalemia; age younger than 35 years; or adrenal nodule(s). Patients previously tested for PA were excluded.

Exposure

A noninterruptive BPA was developed to trigger for PA screening candidates seen in outpatient setting by clinicians who treat hypertension. The BPA included an order set for PA screening and a link to results interpretation guidance.

Main Outcomes and Measures

(1) The number of PA screening candidates identified by the BPA between October 1, 2021, and December 31, 2022; (2) the rates of PA screening; and (3) the BPA use patterns, stratified by physician specialty were assessed.

Results

Over 15 months, the BPA identified 14 603 unique candidates (mean [SD] age, 65.5 [16.9] years; 7300 women [49.9%]; 371 [2.5%] Asian, 2383 [16.3%] Black, and 11 225 [76.9%] White individuals) for PA screening, including 7028 (48.1%) with treatment-resistant hypertension, 6351 (43.5%) with hypokalemia, 1537 (10.5%) younger than 35 years, and 445 (3.1%) with adrenal nodule(s). In total, 2040 patients (14.0%) received orders for PA screening. Of these, 1439 patients (70.5%) completed the recommended screening within the system, and 250 (17.4%) had positive screening results. Most screening orders were placed by internists (40.0%) and family medicine physicians (28.1%). Family practitioners (80.3%) and internists (68.9%) placed most orders via the embedded order set, while specialists placed most orders (83.0%-95.4%) outside the BPA. Patients who received screening were younger and included more women and Black patients than those not screened. The likelihood of screening was higher among patients with obesity and dyslipidemia and lower in those with chronic kidney disease and established cardiovascular complications.

Conclusions and Relevance

The study results suggest that noninterruptive BPAs are potentially promising PA screening-assistance tools, particularly among primary care physicians. Combined with artificial intelligence algorithms that optimize the detection yield, refined BPAs may contribute to personalized hypertension care.

A Novel Receivership Model for Transition of Young Adults With Diabetes: Experience From a Single-center Academic Transition Program

OBJECTIVE

The transition from pediatric to adult care for young adults with diabetes represents an important but often challenging time characterized by a shift from a family-centered care model of pediatrics to a patient-centered care model of adult medicine. We developed a structured transition program based on an adult receivership model at a large academic medical center to improve care coordination and patient satisfaction with the transition process.

METHODS

From 2016 to 2020, we implemented a series of quality improvement efforts for young adults aged 18 to 23 years with diabetes by incorporating best practices from the American Diabetes Association guidelines on care for emerging adults. We measured transition orientation attendance, patient satisfaction, hemoglobin A1c (HbA1c) pre- and post-transfer, and care gaps to determine the impact of the program.

RESULTS

In this study, 307 individuals with type 1 diabetes and 16 individuals with type 2 diabetes were taken care of by the adult endocrinology department at the University of Michigan between January 1, 2016 and October 31, 2020. We observed high attendance rates (86% among internal transfers) and favorable patient satisfaction scores for the transition orientation session. Despite the glycemic challenges posed during the transition, HbA1c modestly yet significantly improved 1-year after transfer (-0.4%, P < .01).

CONCLUSION

We successfully established and maintained a young adult diabetes transition program using a quality improvement approach. Future work will focus on reducing care gaps at the time of transfer, assessing long-term retention rates, and enhancing care coordination for patients referred from outside the health network.

Improving the quality of blood pressure measurements in an outpatient diabetes clinic

Hypertension is an important modifiable risk factor for cardiovascular disease in patients with diabetes. Despite established guidelines, the percentage of patients meeting the target blood pressure (BP) of <140/90 mm Hg in clinic remains suboptimal. In this project, we sought to improve BP measurement in an outpatient diabetes clinic.

Two interventions were performed: (1) Changes were made to the timing of BP measurement during patient intake and (2) An electronic medical record (EMR) alert reminded staff to repeat BP if the initial reading was above target. Baseline data were collected on 4764 patients, with 72.5% meeting their BP target. After implementation of changes to the timing of BP measurement during patient intake, 73.3% of patients met the target (no significant change). However, after implementation of the EMR alert, there was a statistically significant improvement in patients meeting the target BP at 76.8% (p<0.01). This reduction was driven by the high percentage of patients with an initially elevated BP measurement that came down into goal range on repeat measurement. Those who remained above target despite multiple readings could be referred to a new pharmacist-led hypertension clinic to ensure adequate follow-up and medication adjustment.

It is important to ensure that in clinic BP measurements are taken correctly and adhere to best practices. Use of a single in-clinic BP measurement may result in overtreatment of hypertension. While timing of BP measurement during patient intake was not important, repeating high BP measurements did improve the number of patients in an outpatient diabetes clinic meeting their BP target.

Imputing HbA1c from capillary blood glucose levels in patients with type 2 diabetes in Sri Lanka: a cross-sectional study

OBJECTIVE

To develop a population-specific methodology for estimating glycaemic control that optimises resource allocation for patients with diabetes in rural Sri Lanka.

DESIGN

Cross-sectional study.

SETTING

Trincomalee, Sri Lanka.

PARTICIPANTS

Patients with non-insulin-treated type 2 diabetes (n=220) from three hospitals in Trincomalee, Sri Lanka.

OUTCOME MEASURE

Cross-validation was used to build and validate linear regression models to identify predictors of haemoglobin A1c (HbA1c). Validation of models that regress HbA1c on known determinants of glycaemic control was thus the major outcome. These models were then used to devise an algorithm for categorising the patients based on estimated levels of glycaemic control.

RESULTS

Time since last oral intake other than water and capillary blood glucose were the statistically significant predictors of HbA1c and thus included in the final models. In order to minimise type II error (misclassifying a high-risk individual as low-risk or moderate-risk), an algorithm for interpreting estimated glycaemic control was created. With this algorithm, 97.2% of the diabetic patients with HbA1c ≥9.0% were correctly identified.

CONCLUSIONS

Our calibrated algorithm represents a highly sensitive approach for detecting patients with high-risk diabetes while optimising the allocation of HbA1c testing. Implementation of these methods will optimise the usage of resources devoted to the management of diabetes in Trincomalee, Sri Lanka. Further external validation with diverse patient populations is required before applying our algorithm more widely.

Identification of population characteristics through implementation of the Comprehensive Diabetic Retinopathy Program

Background

Diabetic retinopathy is the most common cause of blindness in working-age adults. Characteristics of patients with diabetes presenting to a retina subspecialty clinic have not been adequately studied, limiting our ability to risk stratify patients with diabetic retinopathy. Our goal is to describe an innovative program that collects structured, longitudinal data on patients with diabetes in a retina clinic, and identifies population characteristics to define patient risk stratification.

Methods

Demographics, body-mass index, blood pressure, hemoglobin A_1c, smoking history, diabetes type, diabetes duration, kidney disease history, and diagnosis codes were collected on all patients with diabetes at the Kellogg Eye Center retina clinic. A mixed effects negative binomial regression was then performed to assess visit frequency as a function of these variables. Visit frequency was used as a marker for cost of care. A subgroup of patients was surveyed about knowledge of diabetes management goals and barriers to better self-management.

Results

There were 2916 patients in the cohort with 1014 in the subgroup. The cohort was predominantly Caucasian (74.5%), with a mean age of 64 years (range 13–99) and a relatively even distribution of sex (53.2% men). The mean maximum hemoglobin A_1c was 8.0% (range 4.3–15.7%), and 57.1% had a diagnosis of diabetic retinopathy. Patients averaged 3.9 visits (range 1–27) during the 18-month study period. Blood pressure and duration of diabetes were positively associated with visit frequency (p < 0.0001, p < 0.0001, respectively). Of the surveyed patients, 87.6% knew their goal hemoglobin A_1c, while only 45.9% identified the correct blood pressure goal. The most common reported barrier to better self-management was “it’s just not working” (47.1%).

Conclusions

Implementation of this program enables the creation of a longitudinal dataset on patients with diabetes. Resulting data can be used to improve quality of care provided to patients at a retina clinic. The findings suggest considerable healthcare resources are being directed to a small patient population. This enhanced understanding of characteristics of patients with diabetes will improve efforts to preserve vision and utilize health system resources efficiently.

A new model for diabetes-focused capacity building - lessons from Sri Lanka

Sri Lanka is experiencing a rapid increase in the number of people with diabetes mellitus (DM) due to population growth and aging. Physician shortages, outdated technology, and insufficient health education have contributed to the difficulties associated with managing the burden of disease. New models of chronic disease management are needed to address the increasing prevalence of DM.

Medical students, business students, and faculty members from the University of Michigan partnered with the Grace Girls’ Home, Trincomalee General Hospital, and Selvanayakapuram Central Hospital to identify and train diabetes-focused medical assistants (MAs) to collect and enter patient data and educate patients about their disease. Return visits to these MAs were encouraged so that patient progress and disease progression could be tracked longitudinally. Data entry was conducted through a cloud-based mechanism, facilitating patient management and descriptive characterization of the population. We implemented this pilot program in June 2016 in coordination with Trincomalee General Hospital and Selvanayakapuram Central Hospital. Over a 12-month period, 93 patients were systematically assessed by the medical assistants. All patients received education and were provided materials after the visit to better inform them about the importance of controlling their disease. Fifteen percent (14/93) of patients returned for follow-up consultation.

Trained MAs have the potential to provide support to physicians working in congested health systems in low-resource settings. Public investment in training programs for MAs and greater acceptance by physicians and patients will be essential for handling the growing burden associated with chronic illnesses like DM. Trained MAs may also play a role in improved patient education and awareness regarding diabetes self-management.

DNA methylation associated with healthy aging of elderly twins

Variation in healthy aging and lifespan is ascribed more to various non-genetic factors than to inherited genetic determinants, and a major goal in aging research is to reveal the epigenetic basis of aging. One approach to this goal is to find genomic sites or regions where DNA methylation correlates with biological age. Using health data from 134 elderly twins, we calculated a frailty index as a quantitative indicator of biological age, and by applying the Infinium HumanMethylation450K BeadChip technology to their leukocyte DNA samples, we obtained quantitative DNA methylation data on genome-wide CpG sites. We analyzed the health and epigenome data by taking two independent associative approaches: the parametric regression-based approach and a non-parametric machine learning approach followed by GO ontology analysis. Our results indicate that DNA methylation at CpG sites in the promoter region of PCDHGA3 is associated with biological age. PCDHGA3 belongs to clustered protocadherin genes, which are all located in a single locus on chromosome 5 in human. Previous studies of the clustered protocadherin genes showed that (1) DNA methylation is associated with age or age-related phenotypes; (2) DNA methylation can modulate gene expression; (3) dysregulated gene expression is associated with various pathologies; and (4) DNA methylation patterns at this locus are associated with adverse lifetime experiences. All these observations suggest that DNA methylation at the clustered protocadherin genes, including PCDHGA3, is a key mediator of healthy aging.

DNA LIGASE IV SYNDROME: A RARE CAUSE OF GROWTH FAILURE & HYPOGONADISM

Objective

DNA ligase IV syndrome is a rare genetic disorder characterized by pronounced radiosensitivity, growth failure, pancytopenia, hypogonadism, and immunodeficiency. Here, we describe a unique case of DNA ligase IV syndrome diagnosed in adulthood and review the endocrine manifestations of this rare disorder.

Methods

We present detailed clinical, laboratory, and exam findings and review the relevant literature.

Results

This patient initially presented in childhood with microcephaly, growth failure, and mild pancytopenia. At age 18, she developed secondary amenorrhea, with labs revealing hypergonadotropic hypogonadism. She was initially suspected to have Turner syndrome, but karyotype testing was normal. At age 34, genetic testing ultimately confirmed the diagnosis of DNA ligase IV syndrome.

Conclusion

Severe growth failure and hypogonadism are important endocrine clues to the diagnosis of DNA ligase IV syndrome. The increased availability of genetic testing and whole-exome sequencing may allow for definitive diagnosis in patients that previously went unrecognized.

Subcutaneous glucagon infusion and continuous glucose monitoring enable effective management of hypoglycemia in a patient with IGF-2-producing hemangiopericytoma

Background

Ectopic insulin-like growth factor (IGF)-2 production is a rare complication of an array of epithelial and mesenchymal tumors, and can clinically manifest as life-threatening hypoglycemia.

Case presentation

A 49-year-old woman with 13-year history of metastatic hemangiopericytoma, previously treated with multiple rounds of chemotherapy and palliative radiation, presented to the emergency department after a hypoglycemic seizure. On arrival, glucose was 18 mg/dL (1.0 mmol/L) and required continuous dextrose infusion for maintenance within normal limits. Insulin was <2.0 μU/mL, C-peptide 0.1 ng/mL, and beta-hydroxybutyrate <0.2 mmol/L. Random cortisol was 21 μg/dL; sulfonylurea screen, and insulin antibodies were negative. IGF-2 level was 1320 ng/mL; IGF-1 was within normal limits and IGF binding protein (BP)-3 suppressed. Dexamethasone, started at 6 mg twice daily, allowed discontinuation of the glucose infusion. Given concern for nocturnal hypoglycemia, and patient interest in steroid-sparing anti-hypoglycemic regimen, she was also started on overnight continuous subcutaneous glucagon infusion via insulin pump. She was discharged with instructions to maintain a diet high in complex carbohydrates during the day, while utilizing glucagon pump at night. She was also started on continuous glucose monitoring system (CGMS) with an alarm to warn of hypoglycemia. Glucagon infusion rate was later titrated based on CGMS readings. Abdominal CT revealed increasing size of a right upper quadrant mass not previously subjected to radiotherapy. After radiation to this area, hypoglycemia improved, allowing further glucagon titration. In parallel, IGF-2 level declined to 380 ng/mL.

Conclusions

Ectopic IGF-2 production is a rare but often fatal complication of many cancers, and should be considered on the differential diagnosis in patients with malignancy and unexplained hypoglycemia. Once hypoglycemia is diagnosed, patients often have end-stage disease. While treatment of the causative tumor is the only definitive intervention, anti-hypoglycemia therapy is a life-saving, temporizing measure. In this case, the patient attained euglycemia and survived 3 months after presentation before ultimately succumbing to other malignancy-related complications. Given efficacy in management of hypoglycemia while awaiting definitive tumor-directed therapy, we submit nighttime subcutaneous glucagon infusion and CGMS are valuable additions to the physician’s armamentarium in managing this condition.

Acute pseudogout of the foot following Parathyroidectomy: a case report

Background

The current case report is the first in the literature to report the association between parathyroidectomy and an episode of probable pseudogout in the foot in a patient with diabetes mellitus.

Case presentation

The authors present a case of pseudogout of the left foot following a subtotal parathyroidectomy in an 80-year-old female with type 2 diabetes mellitus and primary hyperparathyroidism. Pseudogout, also known as calcium pyrophosphate dehydrate deposition disease, is an unusual metabolic sequela following parathyroidectomy. Pseudogout attacks have been noted in the immediate post-operative period following parathyroidectomy, but has rarely been identified in the foot. The diagnosis was challenging and there were multiple differential diagnoses that were entertained in this case.

Conclusions

This case illustrates the importance of reviewing the surgical history as there might be a link between the previous surgeries and current foot problems. This case also serves as a reminder of the importance of calcium and phosphate metabolism in podiatric health. Most specifically it demonstrates again the association of pseudogout and parathyroidectomy in a patient with diabetes mellitus. Although a rare occurrence, it is an important reminder that metabolic imbalances of calcium levels can manifest in any bone.

Application of One-Step IADPSG Versus Two-Step Diagnostic Criteria for Gestational Diabetes in the Real World: Impact on Health Services, Clinical Care, and Outcomes

PURPOSE OF REVIEW

This paper seeks to summarize the impact of the one-step International Association of Diabetes and Pregnancy Study Groups (IADPSG) versus the two-step gestational diabetes mellitus (GDM) criteria with regard to prevalence, outcomes, healthcare delivery, and long-term maternal metabolic risk.

RECENT FINDINGS

Studies demonstrate a 1.03-3.78-fold rise in the prevalence of GDM with IADPSG criteria versus baseline criteria. Women with GDM by IADPSG criteria have more adverse pregnancy outcomes than women with normal glucose tolerance (NGT). Treatment of GDM by IADPSG criteria may be cost effective. Use of the fasting glucose as a screen before the 75-g oral glucose tolerance test to rule out GDM with fasting plasma glucose (FPG) < 4.4 (80 mg/dl) and rule in GDM with FPG ≥ 5.1 mmol/l (92 mg/dl) reduces the need for OGTT by 50% and its cost and inconvenience. The prevalence of postpartum abnormal glucose metabolism is higher for women with GDM diagnosed by IADPSG criteria versus that for women with NGT. Data support the use of IADPSG criteria, if the cost of diagnosis and treatment can be controlled and if lifestyle can be optimized to reduce the risk of future diabetes.

The frailty index outperforms DNA methylation age and its derivatives as an indicator of biological age

The measurement of biological age as opposed to chronological age is important to allow the study of factors that are responsible for the heterogeneity in the decline in health and function ability among individuals during aging. Various measures of biological aging have been proposed. Frailty indices based on health deficits in diverse body systems have been well studied, and we have documented the use of a frailty index (FI₃₄) composed of 34 health items, for measuring biological age. A different approach is based on leukocyte DNA methylation. It has been termed DNA methylation age, and derivatives of this metric called age acceleration difference and age acceleration residual have also been employed. Any useful measure of biological age must predict survival better than chronological age does. Meta-analyses indicate that age acceleration difference and age acceleration residual are significant predictors of mortality, qualifying them as indicators of biological age. In this article, we compared the measures based on DNA methylation with FI₃₄. Using a well-studied cohort, we assessed the efficiency of these measures side by side in predicting mortality. In the presence of chronological age as a covariate, FI₃₄ was a significant predictor of mortality, whereas none of the DNA methylation age-based metrics were. The outperformance of FI₃₄ over DNA methylation age measures was apparent when FI₃₄ and each of the DNA methylation age measures were used together as explanatory variables, along with chronological age: FI₃₄ remained significant but the DNA methylation measures did not. These results indicate that FI₃₄ is a robust predictor of biological age, while these DNA methylation measures are largely a statistical reflection of the passage of chronological time.

Lamellipodin promotes invasive 3D cancer cell migration via regulated interactions with Ena/VASP and SCAR/WAVE

Cancer invasion is a hallmark of metastasis. The mesenchymal mode of cancer cell invasion is mediated by elongated membrane protrusions driven by the assembly of branched F-actin networks. How deregulation of actin regulators promotes cancer cell invasion is still enigmatic. We report that increased expression and membrane localization of the actin regulator Lamellipodin correlate with reduced metastasis-free survival and poor prognosis in breast cancer patients. In agreement, we find that Lamellipodin depletion reduced lung metastasis in an orthotopic mouse breast cancer model. Invasive 3D cancer cell migration as well as invadopodia formation and matrix degradation was impaired upon Lamellipodin depletion. Mechanistically, we show that Lamellipodin promotes invasive 3D cancer cell migration via both actin-elongating Ena/VASP proteins and the Scar/WAVE complex, which stimulates actin branching. In contrast, Lamellipodin interaction with Scar/WAVE but not with Ena/VASP is required for random 2D cell migration. We identified a phosphorylation-dependent mechanism that regulates selective recruitment of these effectors to Lamellipodin: Abl-mediated Lamellipodin phosphorylation promotes its association with both Scar/WAVE and Ena/VASP, whereas Src-dependent phosphorylation enhances binding to Scar/WAVE but not to Ena/VASP. Through these selective, regulated interactions Lamellipodin mediates directional sensing of epidermal growth factor (EGF) gradients and invasive 3D migration of breast cancer cells. Our findings imply that increased Lamellipodin levels enhance Ena/VASP and Scar/WAVE activities at the plasma membrane to promote 3D invasion and metastasis.

Non-coding genomic regions possessing enhancer and silencer potential are associated with healthy aging and exceptional survival

We have completed a genome-wide linkage scan for healthy aging using data collected from a family study, followed by fine-mapping by association in a separate population, the first such attempt reported. The family cohort consisted of parents of age 90 or above and their children ranging in age from 50 to 80. As a quantitative measure of healthy aging, we used a frailty index, called FI34, based on 34 health and function variables. The linkage scan found a single significant linkage peak on chromosome 12. Using an independent cohort of unrelated nonagenarians, we carried out a fine-scale association mapping of the region suggestive of linkage and identified three sites associated with healthy aging. These healthy-aging sites (HASs) are located in intergenic regions at 12q13-14. HAS-1 has been previously associated with multiple diseases, and an enhancer was recently mapped and experimentally validated within the site. HAS-2 is a previously uncharacterized site possessing genomic features suggestive of enhancer activity. HAS-3 contains features associated with Polycomb repression. The HASs also contain variants associated with exceptional longevity, based on a separate analysis. Our results provide insight into functional genomic networks involving non-coding regulatory elements that are involved in healthy aging and longevity.

Using oral agents to manage gestational diabetes: what have we learned?

Insulin has been the mainstay of treatment of diabetes during pregnancy for decades. Although glyburide and metformin are classified as category B during pregnancy, recent research has suggested that these oral agents alone or in conjunction with insulin may be safe for the treatment of gestational diabetes (GDM). This paper summarizes the data on the use of glyburide and metformin for treatment of GDM.

Under-recognised paradox of neuropathy from rapid glycaemic control

Insulin induced neuropathy has been reported previously in people with diabetes treated with insulin, and subsequently reported in patients with insulinomas. However, neuropathy caused by rapid glycaemic control in patients with poorly controlled diabetes with chronic hyperglycaemia is not a widely recognised entity among clinicians worldwide. It is expected that this phenomenon of paradoxical complication of neuropathy in the face of drastic decreases in glycosylated haemoglobin concentrations will assume greater importance with clinicians achieving glycaemic targets at a faster pace than before.

Acute hyperglycemic crisis in the elderly

The geriatric population is at particular risk for developing hyperglycemic crises with the development of diabetes. With increasing age, insulin secretory reserve, insulin sensitivity, and thirst mechanisms decrease. The elderly are particularly vulnerable to hyperglycemia and dehydration, the key components of hyperglycemic emergencies. If recognized early, hyperglycemia can frequently be treated in the outpatient setting even with moderate or large ketonuria, provided patients can take fluids, monitor blood glucose frequently, and follow standard "sick day rules." With increased diabetes surveillance and aggressive early treatment of hyperglycemia and its complications, morbidity and mortality from acute diabetic crises in the geriatric population can be greatly reduced.

Epidermal growth factor receptor distribution during chemotactic responses

To determine the distribution of the epidermal growth factor (EGF) receptor (EGFR) on the surface of cells responding to EGF as a chemoattractant, an EGFR-green fluorescent protein chimera was expressed in the MTLn3 mammary carcinoma cell line. The chimera was functional and easily visualized on the cell surface. In contrast to other studies indicating that the EGFR might be localized to certain regions of the plasma membrane, we found that the chimera is homogeneously distributed on the plasma membrane and becomes most concentrated in vesicles after endocytosis. In spatial gradients of EGF, endocytosed receptor accumulates on the upgradient side of the cell. Visualization of the binding of fluorescent EGF to cells reveals that the affinity properties of the receptor, together with its expression level on cells, can provide an initial amplification step in spatial gradient sensing.

Imaging of cancer invasion and metastasis using green fluorescent protein

The use of green fluorescent protein to fluorescently tag tumour cells has allowed investigators to open the "black box" of metastasis in order to visualise the behaviour of tumour cells in living tissues. Analysis of cells leaving the primary tumour indicates that highly metastatic cells are able to polarise more effectively towards blood vessels while poorly metastatic cells fragment more often when interacting with blood. In addition, there appear to be greater numbers of host immune system cells interacting with metastatic tumours. After arresting in target organs such as the lungs or liver, most tumour cells become dormant or apoptose. A small fraction of the arrested cells form metastases. In some target organs, migration of tumour cells may enhance the ability to form metastases.

Correlation of beta-actin messenger RNA localization with metastatic potential in rat adenocarcinoma cell lines

The actin cytoskeleton is involved in the motility of tumor cells. It has been shown in several cell types that beta-actin mRNA is localized in the protrusions of cells in which actin is actively polymerized, and the ability to localize mRNA is correlated with the efficiency of motility. In this context, we studied the distribution of beta-actin mRNA in two different tumor cell lines and correlated it with their metastatic potential. The two cell lines used were the highly metastatic MTLn3 cells and nonmetastatic MTC cells. Nonmetastatic MTC cells have two different pools of beta-actin mRNA (perinuclear and at the leading edge), whereas highly metastatic MTLn3 cells have only a perinuclear distribution of beta-actin mRNA. These differences in mRNA localization are correlated with profound differences in the polarity and plasticity of cell motility of these cells in culture and the histopathology of primary breast tumors derived from these cells. In particular, MTLn3 cells are unpolarized by all cell shape and motility criteria in culture and in their histopathological organization in primary tumors. By comparison, MTC cells are polarized in all identical measurements. These results suggest that the increased plasticity of cell locomotion and the invasiveness of MTLn3 cells result from the failure of metastatic cells to localize beta-actin mRNA properly, causing them to be less polarized and therefore more flexible in their direction of motility. Thus, differences in the polarized organization of cells in the primary tumor that are correlated with beta-actin mRNA localization may have prognostic value in predicting metastatic potential.

The effect of F-actin on the binding and hydrolysis of guanine nucleotide by Dictyostelium elongation factor 1A

Indirect evidence implicates actin as a cofactor in eukaryotic protein synthesis. The present study directly examines the effects of F-actin on the biochemical properties of eukaryotic elongation factor 1A (eEF1A, formerly EF1alpha), a major actin-binding protein. The basal mechanism of eEF1A alone is determined under physiological conditions with the critical finding that glycerol and guanine nucleotide are required to prevent protein aggregation and loss of enzymatic activity. The dissociation constants (Kd) for GDP and GTP are 2.5 microM and 0.6 microM, respectively, and the kcat of GTP hydrolysis is 1.0 x 10(-3) s-1. When eEF1A binds to F-actin, there is a 7-fold decrease in the affinity for guanine nucleotide and an increase of 35% in the rate of GTP hydrolysis. Based upon our results and the relevant cellular concentrations, the predominant form of cellular eEF1A is calculated to be GTP.eEF1A.F-actin. We conclude that F-actin does not significantly modulate the basal enzymatic properties of eEF1A; however, actin may still influence protein synthesis by sequestering GTP.eEF1A away from interactions with its known translational ligands, e.g. aminoacyl-tRNA and ribosomes.

Elongation factor-1 alpha is an overexpressed actin binding protein in metastatic rat mammary adenocarcinoma

Overexpression of elongation factor-1 alpha (EF1 alpha) mRNA has been correlated with increased metastatic potential in mammary adenocarcinoma; however, this relationship was not explored at the level of protein expression. As EF1 alpha has been shown in other cell types to be a component of the actin cytoskeleton, a likely effector in metastasis, the actin binding activity of EF1 alpha from metastatic and nonmetastatic rat breast tumors and cell lines was investigated. We have shown that EF1 alpha protein is overexpressed in metastatic compared to nonmetastatic cells and whole tumors. Similarly to other EF1 alpha s, both types of tumor EF1 alpha bind to F-actin, but EF1 alpha from metastatic cells has a reduced affinity for actin. In addition, there is a high correlation between the intracellular distribution of filamentous actin and EF1 alpha in those cytoskeletal structures thought to be important for supporting the cellular motility required for metastasis. Following stimulation with EGF, there is a parallel increase in the amount of F-actin and EF1 alpha associated with the cytoskeleton. The response to EGF can be blocked with cytochalasin D indicating that the binding of EF1 alpha to the cytoskeleton is mediated by F-actin. We propose that a weakened association of EF1 alpha with actin may be related to the metastatic process via an altered organization of the actin cytoskeleton and the differential translation of mRNAs associated with the cytoskeleton.

Breast irradiation in the older woman: a toxicity study

OBJECTIVE

To establish the tolerance of breast irradiation by women aged 65 and older.

DESIGN

Retrospective chart review.

PATIENTS AND SETTING

Women undergoing partial mastectomy and postoperative radiation therapy at the H. Lee Moffitt Cancer Center and Research Institute between 1986 and 1990. Of 163 women eligible for the study, 100 were under age 65, and 63 were aged 65-78.

MEASUREMENTS

Comparison of total treatment dose, treatment duration, number of treatment interruptions, incidence of cutaneous, mucosal, and hematological toxicity between women aged 65 and older and women younger than age 65.

MAIN RESULTS

All study measurements were comparable among younger and older women: total radiation dose (P = 0.5); treatment interruptions (P = 0.063); treatment duration (P = 0.78); cutaneous toxicity (P = 0.37); anemia (P = 0.83); leukopenia (P = 0.07), and thrombocytopenia (P = 0.94). There was no mucosal toxicity, nor higher than grade 2 hematological or cutaneous toxicity. The incidence and severity of toxicity was not higher for women aged 70 and older.

CONCLUSIONS

Postoperative breast irradiation is well tolerated by older women. Age is not a contraindication to breast preservation.