Greater muscle volume and muscle fat infiltrate in the deep cervical spine extensor muscles (multifidus with semispinalis cervicis) in individuals with chronic idiopathic neck pain compared to age and sex-matched asymptomatic controls: a cross-sectional study

Muscle size and composition (muscle volume and muscle fat infiltrate [MFI]) may provide insight into possible mechanisms underpinning chronic idiopathic neck pain, a common condition with no definitive underlying pathology. In individuals with chronic idiopathic neck pain > 3 months and age- and sex-matched asymptomatic controls, muscle volumes of levator scapulae, multifidus including semispinalis cervicis (MFSS), semispinalis capitis, splenius capitis including splenius cervicis (SCSC), sternocleidomastoid and longus colli from C3 through T1 were quantified from magnetic resonance imaging. Between-group differences were determined using linear mixed models, accounting for side (left or right), muscle, spinal level, sex, age, and body mass index (BMI). Individuals with pain had greater muscle volume (mean difference 76.8mm³; 95% CI 26.6-127.0; p = .003) and MFI (2.3%; 0.2-4.5; p = .034) of the MFSS compared to matched controls with no differences in relative volume, accounting for factors associated with the outcomes: muscle, spinal level, side (left had smaller volume, relative volume and MFI than right), sex (females had less volume and relative volume than males), age (older age associated with less relative volume and greater MFI), and BMI (higher BMI associated with greater muscle volume and MFI). Greater MFI in individuals with chronic idiopathic neck pain suggests a possible underlying mechanism contributing to neck pain. Perspective: These findings suggest MFI in the MFSS may be radiologic sign, potentially identifying patients with a less favourable prognosis. Future studies are needed to confirm this finding and determine if MFI is a contributor to the development or persistence of neck pain, or consequence of neck pain.

High-Throughput CRISPR-Cas13 SARS-CoV-2 Test

BACKGROUND

The ability to control the spread of COVID-19 continues to be hampered by a lack of rapid, scalable, and easily deployable diagnostic solutions.

METHODS

: We developed a diagnostic method based on CRISPR that can deliver sensitive, specific, and high-throughput detection of Sudden Acute Respiratory Syndrome-Coronavirus-2 (SARS-CoV-2). The assay utilizes SHERLOCK (Specific High-sensitivity Enzymatic Reporter unLOCKing) for the qualitative detection of SARS-CoV-2 RNA and may be performed directly on a swab or saliva sample without nucleic acid extraction. The assay uses a 384-well format and provides results in less than one hour.

RESULTS

Assay performance was evaluated with 105 (55 negative, 50 positive) remnant SARS-CoV-2 specimens previously identified as positive using Food and Drug Administration emergency use authorized assays and re-tested with a modified version of the Centers for Disease Control and Prevention (CDC) RT-qPCR assay. When combined with magnetic bead-based extraction, the high throughput SHERLOCK SARS-CoV-2 assay was 100% concordant (n = 60) with the CDC RT-qPCR. When used with direct sample addition the high throughput assay was also 100% concordant with the CDC RT-qPCR direct method (n = 45). With direct saliva sample addition, the negative and positive percent agreements were 100% (15/15, 95% CI : 81.8-100%) and 88% (15/17, 95% CI : 63.6-98.5%), respectively, compared with results from a collaborating clinical laboratory.

CONCLUSIONS

This high throughput assay identifies SARS-CoV-2 from patient samples with or without nucleic acid extraction with high concordance to RT-qPCR methods. This test enables high complexity laboratories to rapidly increase their testing capacities with simple equipment.

Mobilizing Older Adults: Harnessing the Potential of Smart Home Technologies. Contribution of the IMIA Working Group on Smart Homes and Ambient Assisted Living

OBJECTIVES

This paper highlights the potential of smart home applications to not only assess mobility determinants for older adults in the home environment but also provide the opportunity for tailored interventions.

METHODS

We present a theoretical framework for assessing mobility parameters and utilizing this information to enable behavior change based on the Health Belief Model. We discuss examples that showcase the potential of smart home systems to not only measure but also improve mobility for community dwelling older adults.

RESULTS

Mobility is a complex construct that cannot be addressed with a single monitoring approach or a single intervention. Instead, tailored interventions that address specific needs and behaviors of individuals and take into consideration preferences of older adults and potentially their social network are needed to effectively enforce positive behavior change. Smart home systems have the ability to capture details of one's daily living that could otherwise not be easily obtained; however, such data repositories alone are not sufficient to improve clinical outcomes if appropriate mechanisms for data mining and analysis, as well as tailored response systems are not in place.

CONCLUSIONS

Unleashing the potential of smart home applications to measure and improve mobility has the potential of transforming elder care and providing potentially cost-effective tools to support independence for older adults. A technologically driven smart home application can maximize its clinical relevance by pursuing interactive features that can lead to behavior change.

Delayed inhibition of Nogo-A does not alter injury-induced axonal sprouting but enhances recovery of cognitive function following experimental traumatic brain injury in rats

Traumatic brain injury causes long-term neurological motor and cognitive deficits, often with limited recovery. The inability of CNS axons to regenerate following traumatic brain injury may be due, in part, to inhibitory molecules associated with myelin. One of these myelin-associated proteins, Nogo-A, inhibits neurite outgrowth in vitro, and inhibition of Nogo-A in vivo enhances axonal outgrowth and sprouting and improves outcome following experimental CNS insults. However, the involvement of Nogo-A in the neurobehavioral deficits observed in experimental traumatic brain injury remains unknown and was evaluated in the present study using the 11C7 monoclonal antibody against Nogo-A. Anesthetized, male Sprague-Dawley rats were subjected to either lateral fluid percussion brain injury of moderate severity (2.5-2.6 atm) or sham injury. Beginning 24 h post-injury, monoclonal antibody 11C7 (n=17 injured, n=6 shams included) or control Ab (IgG) (n=16 injured, n=5 shams included) was infused at a rate of 5 microl/h over 14 days into the ipsilateral ventricle using osmotic minipumps connected to an implanted cannula. Rats were assessed up to 4 weeks post-injury using tests for neurological motor function (composite neuroscore, and sensorimotor test of adhesive paper removal) and, at 4 weeks, cognition was assessed using the Morris water maze. Hippocampal CA3 pyramidal neuron damage and corticospinal tract sprouting, using an anterograde tracer (biotinylated dextran amine), were also evaluated. Brain injury significantly increased sprouting from the uninjured corticospinal tract but treatment with monoclonal antibody 11C7 did not further increase the extent of sprouting nor did it alter the extent of CA3 cell damage. Animals treated with 11C7 showed no improvement in neurologic motor deficits but did show significantly improved cognitive function at 4 weeks post-injury when compared with brain-injured, IgG-treated animals. To our knowledge, the present findings are the first to suggest that (1) traumatic brain injury induces axonal sprouting in the corticospinal tract and this sprouting may be independent of myelin-associated inhibitory factors and (2) that post-traumatic inhibition of Nogo-A may promote cognitive recovery unrelated to sprouting in the corticospinal tract or neuroprotective effects on hippocampal cell loss following experimental traumatic brain injury.

Experimental models of traumatic brain injury: do we really need to build a better mousetrap?

Approximately 4000 human beings experience a traumatic brain injury each day in the United States ranging in severity from mild to fatal. Improvements in initial management, surgical treatment, and neurointensive care have resulted in a better prognosis for traumatic brain injury patients but, to date, there is no available pharmaceutical treatment with proven efficacy, and prevention is the major protective strategy. Many patients are left with disabling changes in cognition, motor function, and personality. Over the past two decades, a number of experimental laboratories have attempted to develop novel and innovative ways to replicate, in animal models, the different aspects of this heterogenous clinical paradigm to better understand and treat patients after traumatic brain injury. Although several clinically-relevant but different experimental models have been developed to reproduce specific characteristics of human traumatic brain injury, its heterogeneity does not allow one single model to reproduce the entire spectrum of events that may occur. The use of these models has resulted in an increased understanding of the pathophysiology of traumatic brain injury, including changes in molecular and cellular pathways and neurobehavioral outcomes. This review provides an up-to-date and critical analysis of the existing models of traumatic brain injury with a view toward guiding and improving future research endeavors.

Neurogenic fever after traumatic brain injury: an epidemiological study

OBJECTIVES

To determine the incidence of neurogenic fever (NF) in a population of patients in the acute phase following severe traumatic brain injury (TBI); to identify factors associated with the development of NF following severe TBI in adults.

METHODS

Charts of patients admitted from 1996 to 1999 with severe TBI at a large, urban mid-Atlantic teaching hospital were retrospectively evaluated based on diagnostic criteria for each episode of hyperthermia to determine the diagnosis of NF. Data were collected regarding mechanism and area of injury, severity of injury, and demographic factors to determine potential predictors of NF.

RESULTS

Diffuse axonal injury (DAI) (OR 9.06, 95% CI 0.99 to 82.7) and frontal lobe injury of any type (OR 6.68, 95% CI 1.1 to 39.3) are independently predictive of an increased risk of development of NF following severe TBI. The presence of a skull fracture and lower initial Glasgow Coma Score (GCS) were individual predictors of development of NF, but did not contribute to the final model.

CONCLUSIONS

These findings examine known and novel risk factors for this phenomenon in comparison to previously published literature on NF. A set of predictor variables was identified to help clinicians target patients at high risk for development of NF following severe TBI. It is hoped that earlier diagnosis and appropriate intervention for fever in the TBI patient will lead to improved outcomes.

Control of rat mammary epithelium proliferation by conjugated linoleic acid

Past research showed that mammary gland morphogenesis in the pubescent rat was retarded by the feeding of conjugated linoleic acid (CLA). A major objective of the present study was to examine the proliferative activity and the expression of cell cycle regulatory proteins in the developing mammary epithelium of rats fed a mixture of CLA isomers (primarily as free fatty acid c9, t11-CLA and t10,c12-CLA) or a highly enriched natural source of c9,t11-CLA (as triacylglycerol in butterfat). In both experiments, the diets, with or without CLA, were started at weaning and continued for four weeks. The two CLA preparations were equally effective in suppressing bromodeoxyuridine labeling and the expression of cyclin D1 and cyclin A (determined by immunohistochemistry) in the terminal end buds and alveolar clusters of the mammary epithelium while it undergoes extensive ductal branching during pubescence. There was a trend of an increase, although not statistically significant, in the proportion of cells expressing the p16 and p27 cdk inhibitors. A separate experiment was designed to evaluate the effect of c9,t11-CLA (as a free fatty acid of > 90% purity) treatment on the rate of proliferation of the mammary epithelium as the animal matured from weanling to adult. The bromodeoxyuridine labeling data indicated that the mammary epithelium appeared to lose its sensitivity to CLA control of proliferation as it completely filled the fat pad and became quiescent. These observations suggest that the responsiveness of mammary epithelial cells to CLA intervention may be dependent on their proliferative status.

Effect of the aromatase inhibitor vorozole on estrogen and progesterone receptor content of rat mammary carcinomas induced by 1-methyl-1-nitrosourea

Vorozole, a nonsteroidal aromatase inhibitor, impedes the post-initiation stage of chemically induced mammary carcinogenesis. While various aspects of vorozole's effects on mammary carcinoma development have been investigated, little attention has been directed to determining the estrogen receptor (ER) and progesterone receptor (PR) content of mammary carcinomas that arise despite vorozole treatment. Female Sprague-Dawley rats were given an i.p. injection of 50mg MNU/kg body weight at 21 days of age and placed on diet supplemented with 0 or 3 mg vorozole/kg, which had no effect on mammary tumor development. Histologically confirmed carcinomas were evaluated for ER and PR by immunohistochemistry. In the control group, 78.8% of carcinomas were ER positive with an ER content ranging from 13.8 to 40.0%, similar to ER content of mammary ductal epithelial cells from non-carcinogen treated animals. PR content ranged from 4.4 to 45.2% and also was similar to levels of PR observed in ductal epithelial cells. ER was not correlated with PR in mammary carcinomas (r = 0.05, p > 0.80), whereas there was a significant correlation in ductal epithelium (r = 0.86, p = 0.006). In vorozole-treated rats, no ER negative carcinomas were observed and overall ER expression by vorozole was elevated (p < 0.03). All carcinomas from vorozole-treated rats expressed PR (2.5-60.2%) and correlation between ER and PR content was numerically greater in carcinomas from vorozole-treated animals (r = 0.42, p = 0.09). These data, which are considered hypothesis generating, provide evidence that low doses of vorozole in the diet select for mammary carcinomas with an increased ER positive phenotype.

Molecular mechanisms associated with Se-allylselenocysteine regulation of cell proliferation and apoptosis

Se-allylselenocysteine (ASC) has been shown to inhibit mammary carcinogenesis in vivo and cell growth in vitro. However, little is known about the molecular events that account for these effects. The goal of the present study was to use a mouse hyperplastic mammary epithelial cell line, TM12, to investigate the underlying mechanism(s) associated with ASC regulation of cell proliferation and apoptosis. Cells were treated with 50 microM ASC and assessed after 3, 6 and 12 h of exposure. A significant inhibition of cell proliferation, as measured by BrdU incorporation into DNA, was observed within 3 h of ASC treatment. This inhibitory effect was slightly magnified at the later time points. The induction of apoptosis was also rapid, and progressed from a 1.3-fold increase at 3 h to a 4.4-fold increase at 12 h. Consistent with these cellular events, the levels of phosphorylated Rb protein were greatly reduced at all times points. The other accompanying changes included increases in P53, P21 and P27. Collectively, the results demonstrate for the first time that ASC is able to cause an immediate response in the expression of cell cycle regulatory proteins that favor an arrest in proliferation and an augmentation in apoptosis.

Allium chemistry: synthesis, natural occurrence, biological activity, and chemistry of Se-alk(en)ylselenocysteines and their gamma-glutamyl derivatives and oxidation products

Syntheses are reported for gamma-glutamyl Se-methylselenocysteine (Sa), selenolanthionine (16), Se-1-propenylselenocysteine (Gd), Se-2-methyl-2-propenyl-L-selenocysteine (6e), and Se-2-propynyl-L-selenocysteine (6f). Oxidation of 8a and Se-methylselenocysteine (Ga) gives methaneseleninic acid (24), characterized by X-ray crystallography, and dimethyl diselenide (25). Oxidation of Se-2-propenyl-L-selenocysteine (6c) gives allyl alcohol and 3-seleninoalanine (22). Compound 22 is also formed on oxidation of 16 and selenocystine (4). Oxidation of 6d gives 2-[(E,Z)-1-propenylseleno]propanal (36). These oxidations occur by way of selenoxides, detected by chromatographic and spectroscopic methods. The natural occurrence of many of the Se-alk(en)ylselenocysteines and their gamma-glutamyl derivatives and oxidation products is discussed. Three homologues of the potent cancer chemoprevention agents 6a and 6c, namely 6d-f, were evaluated for effects on cell growth, induction of apoptosis, and DNA-damaging activity using two murine mammary epithelial cell lines. Although each compound displays a unique profile of activity, none of these compounds (Gd-f) is likely to exceed the chemopreventive efficacy of selenocysteine Se-conjugates Ga and 6c.

Activity of Se-allylselenocysteine in the presence of methionine gamma-lyase on cell growth, DNA integrity, apoptosis, and cell-cycle regulatory molecules

Se-allylselenocysteine (ASC) is effective in inhibiting mammary epithelial cell growth in vitro and mammary carcinogenesis in vivo, but its mechanism is unknown. We recently reported that ASC reduces cell growth in a dose- and time-dependent manner, induces a loss of DNA integrity, and increases apoptosis. However, the level of ASC required for growth inhibition in vitro is 10- to 20-fold higher than that required in vivo. One possible explanation for this difference is that the cells used in in vitro studies have limited lyase activity required to release the allyl Se moiety from selenocysteine, whereas animals have abundant lyase activity in tissues. In the present study, we found that methionine gamma-lyase (MGL) added to culture medium containing ASC produced biological effects with lower levels of ASC, comparable to the selenium levels in plasma achieved during in vivo chemoprevention. The combination of 2.5 microM ASC and MGL inhibited the growth of TM12 cells and increased apoptosis without loss of DNA integrity. Treatment of TM12 cells with ASC and MGL resulted in an elevation of the protein levels of p53, Cip1/p21, and Kip1/p27, concomitant with a decrease in cyclins D1 and E and modest reductions in cyclin-dependent kinase inhibitors 4 and 2. Cells treated with ASC and MGL also showed decreased phosphorylation of retinoblastoma tumor-suppressor protein. Taken together, these results suggest that a physiologically relevant concentration of ASC with MGL exerts an inhibitory effect on cell growth and that this effect is likely to involve modulation of signaling pathways that suppress the phosphorylation of retinoblastoma tumor-suppressor protein.

Journey towards recovery following physical trauma

Journey towards recovery following physical trauma Convalescence and recovery following illness are of central importance to nursing. These themes have been explored increasingly in the literature. The focus, however, has been primarily on the process of integrating chronic illness into one's life. Recovery from physical injury is rarely addressed. A body of work focusing on physical trauma demonstrates that recovery is often not complete after injuries that have not been viewed as disabling. To illuminate understanding of recovery following physical trauma, the purpose of our 1997 study was to describe more thoroughly the nature of recovery. A total of 63 adults, in a convenience sample, who survived serious physical trauma, were interviewed 2.5 years after injury using an open-ended semistructured interview guide. Three themes were identified: event, fallout, and moving-on. These themes provided the organizing structure for exploring the journey to recovery. This journey, as disclosed by the seriously injured, does not necessarily correspond with the views of most trauma clinicians. Traumatic events create a line of demarcation, separating lives into before and after. The event becomes the starting point of a journey to resume one's life. The event itself is more than the trauma; it is the perceptual and contextual experience that needs to be incorporated into a person's essence. Fallout from the injury is multifaceted and includes physical, psychological, social, and spiritual dimensions. Moving-on in this journey is nonlinear as survivors recognize their lives are forever different. The survivors' accounts suggest that nurses should carefully consider the question, 'What is successful recovery?'

In vitro effects of Se-allylselenocysteine and Se-propylselenocysteine on cell growth, DNA integrity, and apoptosis

Two previously unevaluated selenium compounds, Se-allylselenocysteine (ASC) and Se-propylselenocysteine (PSC), have been shown recently to be active in the chemoprevention of experimentally induced mammary carcinogenesis. Other than their potential as chemopreventive agents, little is known about the pharmacological properties of these compounds. In this article, we report on the in vitro effects of ASC and PSC on cell growth inhibition, apoptosis, and the induction of DNA damage. The effects of ASC and PSC were examined in two mouse mammary epithelial cell lines derived from mammary hyperplasias. These cell lines, designated TM2H and TM12, have mutant or wild-type p53, respectively. It was observed that ASC but not PSC reduced, in a concentration- and time-dependent manner, the number of adherent cells in culture, and this suppressive effect was more prominent in TM12 than in TM2H cells. ASC was also found to induce alkaline-labile DNA damage and the oxidation of pyrimidines, and it also increased the rate of apoptosis. These changes were not seen by exposure to PSC or the sulfur analog of ASC. However, additional data obtained from the intact rat mammary gland suggest that the loss of DNA integrity induced by ASC might not be manifest in vivo at doses of ASC that inhibit carcinogenesis.

Rat models of premalignant breast disease

While a number of agents have been shown to induce mammary carcinogenesis in the rat, premalignant stages of the disease have been best characterized in chemically-induced models, specifically those initiated by either 7,12 dimethylbenz[alpha]anthracene (DMBA) or 1-methyl-1-nitrosourea (MNU). In general, it appears that epithelial cells in mammary terminal end buds or terminal ductules are the targets of carcinogenic initiation, and that a series of morphologically identifiable steps are involved in the development of mammary carcinoma. The premalignant steps include ductal hyperplasia of the usual type and carcinoma in situ of the cribriform or comedo type; atypical ductal hyperplasia has not been reported. Thus the histogenesis of lesions occurring in chemically induced mammary carcinogenesis in the rat is similar to that observed in the human; although, the spectrum of lesions observed in the rat is limited. Opportunities to investigate the biological and molecular characteristics of premalignant breast disease in the rat are presented.

Managing patients with lumbar drainage devices

All nurses who care for patients with LDDs must have demonstrated initial competency with LDDs and should participate in periodic in-service training to maintain that competency. Clearly an educated critical care nurse is the most essential partner that a patient with an LDD can have for preventing complications and ensuring that the best outcomes for the patient are achieved. Nurses caring for patients with an LDD must have a clear institution-specific policy and procedure available to guide the care of these patients.

Managing patients with lumbar drainage devices

All nurses who care for patients with LDDs must have demonstrated initial competency with LDDs and should participate in periodic in-service training to maintain that competency. Clearly an educated critical care nurse is the most essential partner that a patient with an LDD can have for preventing complications and ensuring that the best outcomes for the patient are achieved. Nurses caring for patients with an LDD must have a clear institution-specific policy and procedure available to guide the care of these patients.

In vitro and in vivo studies of methylseleninic acid: evidence that a monomethylated selenium metabolite is critical for cancer chemoprevention

Previous research suggested that the beta-lyase-mediated production of a monomethylated selenium metabolite from Se-methylselenocysteine is a key step in cancer chemoprevention by this agent. In an attempt to affirm the concept, the present study was designed to evaluate the activity of methylseleninic acid, a compound that represents a simplified version of Se-methylselenocysteine without the amino acid moiety, thereby obviating the need for beta-lyase action. The in vitro experiments showed that methylseleninic acid was more potent than Se-methylselenocysteine in inhibiting cell accumulation and inducing apoptosis in TM12 (wild-type p53) and TM2H (nonfunctional p53) mouse mammary hyperplastic epithelial cells, and these effects were not attributable to DNA damage, as determined by the comet assay. In general, methylseleninic acid produced a more robust response at one-tenth the concentration of Se-methylselenocysteine. It is possible that these cell lines may have only a modest ability to generate a monomethylated selenium species from Se-methylselenocysteine via the beta-lyase enzyme. In contrast, methylseleninic acid already serves as a preformed active monomethylated metabolite, and this could be an underlying reason why methylseleninic acid acts more rapidly and exerts a more powerful effect than Se-methylselenocysteine in vitro. Interestingly, the distinction between these two compounds disappeared in vivo, where their cancer chemopreventive efficacies were found to be very similar to each other [in both methylnitrosourea and dimethylbenz(a)anthracene rat mammary tumor models]. The beta-lyase enzyme is present in many tissues; thus, animals have an ample capacity to metabolize Se-methylselenocysteine systemically. Therefore, Se-methylselenocysteine would be expected to behave like methylseleninic acid if beta-lyase is no longer a limiting factor. Taken together, the present in vitro and in vivo results provide strong evidence in support of our earlier hypothesis that a monomethylated selenium metabolite is important for cancer chemoprevention. Methylseleninic acid could be an excellent tool, especially for molecular mechanism studies in cell culture, and some of these attributes are discussed.

Classification of premalignant and malignant lesions developing in the rat mammary gland after injection of sexually immature rats with 1-methyl-1-nitrosourea

Premalignant and malignant stages of mammary carcinogenesis can be rapidly induced by injecting female rats i.p. with 1-methyl-1-nitrosourea (MNU)3 at 21 days of age. In this paper, the characteristics of this model are briefly reviewed and the histology of the lesions induced is presented and compared to those that occur in humans. Malignant mammary lesions induced in rats injected with MNU at 21 days of age are compared with the lesions that develop when MNU is administered to 50-day-old female rats.

Plasma xanthophyll carotenoids correlate inversely with indices of oxidative DNA damage and lipid peroxidation

Post hoc analysis of data obtained from a study designed to modulate oxidative damage by dietary intervention revealed consistently strong inverse correlations between plasma xanthophyll carotenoids and oxidative damage indices. Thirty-seven women participated in a 14-day dietary intervention that increased mean vegetable and fruit (VF) consumption to approximately 12 servings/day. An additional 10 subjects participated in an intervention that limited VF consumption to less than four servings per day. 8-Hydroxy-2'-deoxyguanosine (8-OHdG) in DNA isolated from peripheral lymphocytes and 8-OHdG excreted in urine were measured as indices of oxidative DNA damage. Lipid peroxidation was assessed by measuring 8-epiprostaglandin F2alpha (8-EPG) in urine. Plasma levels of selected carotenoids were also determined, with the intention of using a-carotene as a biochemical index of VF consumption. Urinary 8-OHdG and 8-EPG were measured by ELISA, and plasma carotenoids were measured by high performance liquid chromatography. Lymphocyte 8-OHdG was measured by reverse phase high performance liquid chromatography with electrochemical detection. We observed that the structurally related xanthophyll carotenoids, lutein and beta-cryptoxanthin, which occur in dissimilar botanical families, were consistently inversely associated with these oxidative indices. Statistically significant inverse correlations were observed between plasma lutein and/or beta-cryptoxanthin levels and lymphocyte 8-OHdG and urinary 8-EPG. Moreover, an inverse correlation was observed between change in plasma xanthophylls and change in lymphocyte 8-OHdG concentration that occurred during the course of the study. These data lead us to hypothesize that lutein and beta-cryptoxanthin serve as markers for the antioxidant milieu provided by plants from which they are derived. Whether these carotenoids are directly responsible for the observed antioxidant phenomena merits further investigation.

Mechanisms by which energy restriction inhibits carcinogenesis

Cancer that occurs at numerous organ sites, including the colon and breast, is inhibited by energy restriction, and the inhibition is proportional to the degree of restriction imposed. In an effort to identify the mechanism(s) by which energy restriction exerts this effect, a short term model system of experimentally induced mammary carcinogenesis was used. Given that carcinogenesis is known to involve a dysregulation to tissue size homeostasis in which cell proliferation and cell death are in dysequilibrium, we hypothesized that energy restriction exerts its effect by altering one or more aspects of cell cycle regulation. It was observed that energy restriction inhibited cell proliferation and increased cell death due to apoptosis. Thus attention was next focused on aspects of cell cycle regulation that might be affected by energy restriction. It was observed that the amount of p27 protein, one member of the Cip/Kip family of genes that are involved in cell cycle arrest, was increased dose dependently by energy restriction. Based on this and related observations, the hypothesis is advanced that energy restriction inhibits carcinogenesis, at least in part, by delaying cell cycle progression via shifting cell populations into a G(0)/G(1)state. Ongoing work indicates that corticosteroids, which are produced in increased amounts in response to energy restriction, may be involved in mediating this effect.

Effect of fixation and epitope retrieval on BrdU indices in mammary carcinomas

Studies in which 5-bromo-2'-deoxyuridine (BrdU) is used to quantify rates of cell proliferation are conducted prospectively. Therefore, the opportunity exists to select conditions that optimize detection of the BrdU epitope. The objective of this study was to quantify the extent to which the BrdU epitope was masked by formalin vs methacarn fixation in the assessment of cell proliferation. Mammary carcinomas from animals pulse-labeled with BrdU were trisected. A portion was frozen and the remaining two portions were fixed in 10% neutral buffered formalin or methacarn for 24 hr, processed, embedded in paraffin, and sections stained for incorporated BrdU using a peroxidase immunohistochemical staining technique. Antigen retrieval techniques also were applied to formalin-fixed sections. Fixation in methacarn gave the highest labeling index (16.4%), which was comparable to that observed in unfixed frozen sections (17.5%). Formalin fixation alone dramatically suppressed the labeling index (0.3%), which was only partially recovered using various antigen retrieval techniques (2.1-8.1%). Methacarn fixation is recommended for prospective studies in which BrdU detection is planned because of the quantitative recovery of epitope and the simplicity of the approach.

A comparison of the histopathology of premalignant and malignant mammary gland lesions induced in sexually immature rats with those occurring in the human

The injection of sexually immature female rats with 1-methyl-1-nitrosourea results in a rapid induction of premalignant and malignant mammary gland lesions within 35 days of carcinogen administration. This model affords the opportunity for investigators to study the process of mammary carcinogenesis over a very short latency and to investigate early events in this process. We have recently published on various aspects of this system including the histology of the lesions induced, the time frame of their occurrence, and their dependence on ovarian hormones for their maintenance and growth. In this report we present evidence that many aspects of the histopathology of mammary lesions in this model system are similar to those occurring in humans. We also discuss aspects of the human disease, which are not recapitulated in this model.

Reimbursement for acute care nurse practitioner services

Until the passage of the Balanced Budget Act of 1997, acute care nurse practitioners could not be directly reimbursed for inpatient services provided to Medicare patients. With the enactment of this legislation, acute care nurse practitioners may now be directly compensated for care provided. The historical and contextual issues that surround reimbursement for nursing and advanced practice nursing services are reviewed to serve as a foundation for understanding the current Medicare reimbursement regulations. The implications of the Balanced Budget Act of 1997 for acute care nurse practitioners and their professional colleagues are critically examined. The language of the Balanced Budget Act of 1997 and the subsequent rules and regulations issued by the Health Care Financing Administration are reviewed with specific focus on implications for acute care nurse practitioners. The opportunities for reimbursement for services provided by acute care nurse practitioners are more extensive than ever before. Acute care nurse practitioners and their physician colleagues will be wise to become fully conversant with the changes in Medicare reimbursement regulations.

Reimbursement for acute care nurse practitioner services

Until the passage of the Balanced Budget Act of 1997, acute care nurse practitioners could not be directly reimbursed for inpatient services provided to Medicare patients. With the enactment of this legislation, acute care nurse practitioners may now be directly compensated for care provided. The historical and contextual issues that surround reimbursement for nursing and advanced practice nursing services are reviewed to serve as a foundation for understanding the current Medicare reimbursement regulations. The implications of the Balanced Budget Act of 1997 for acute care nurse practitioners and their professional colleagues are critically examined. The language of the Balanced Budget Act of 1997 and the subsequent rules and regulations issued by the Health Care Financing Administration are reviewed with specific focus on implications for acute care nurse practitioners. The opportunities for reimbursement for services provided by acute care nurse practitioners are more extensive than ever before. Acute care nurse practitioners and their physician colleagues will be wise to become fully conversant with the changes in Medicare reimbursement regulations.

Selenium modulation of cell proliferation and cell cycle biomarkers in normal and premalignant cells of the rat mammary gland

The present study was designed to assess the effect of Se-methylselenocysteine or triphenylselenonium chloride treatment on cell proliferation [bromodeoxyuridine (BrdUrd) labeling] and cell cycle biomarkers [proliferating cell nuclear antigen (PCNA), cyclin D1, and p27/Kip 1] in the intact mammary gland of rats. Immunohistochemical assays of the above end points were carried out in different morphological structures: (a) terminal end bud cells and alveolar cells of a maturing mammary gland undergoing active differentiation; and (b) premalignant mammary intraductal proliferations (IDPs) identified at 6 weeks after carcinogen dosing. Neither compound was found to affect BrdUrd labeling or the expression of cell cycle biomarkers in the normal terminal-end bud cells and alveolar cells. Se-methylselenocysteine reduced the total number of IDP lesions by approximately 60%. Interestingly, this was not accompanied by decreases in BrdUrd labeling or the proportion of IDP cells expressing PCNA and cyclin D1. An enhancement in the fraction of p27/Kip 1-positive IDP cells, however, was detected as a result of Se-methylselenocysteine treatment. Although triphenylselenonium chloride did not reduce the total number of IDPs, there were more of the smaller-sized lesions and fewer of the larger-sized lesions compared with those found in the control group. Triphenylselenonium chloride also significantly decreased the proportion of IDP cells incorporating the BrdUrd label or expressing PCNA and cyclin D1. The above findings suggest that early transformed cells are sensitive to selenium intervention, whereas normal proliferating cells are not. It is possible that Se-methylselenocysteine blocks carcinogenesis by a pathway that may not involve cell growth inhibition as a primary response; in contrast, triphenylselenonium chloride is likely to act by a cytostatic mechanism. The data also imply that selenium efficacy testing in intervention trials is possible with the use of biomarkers, provided that the appropriate biomarkers are matched with the selenium compound of interest and that the pathological characteristics of the cell population to be evaluated are taken into consideration.

Conjugated linoleic acid-enriched butter fat alters mammary gland morphogenesis and reduces cancer risk in rats

Conjugated linoleic acid (CLA) is a potent cancer preventive agent in animal models. To date, all of the in vivo work with CLA has been done with a commercial free fatty acid preparation containing a mixture of c9,t11-, t10,c12- and c11,t13-isomers, although CLA in food is predominantly (80-90%) the c9,t11-isomer present in triacylglycerols. The objective of this study was to determine whether a high CLA butter fat has biological activities similar to those of the mixture of free fatty acid CLA isomers. The following four different endpoints were evaluated in rat mammary gland: 1) digitized image analysis of epithelial mass in mammary whole mount; 2) terminal end bud (TEB) density; 3) proliferative activity of TEB cells as determined by proliferating cell nuclear antigen immunohistochemistry; and 4) mammary cancer prevention bioassay in the methylnitrosourea model. It should be noted that TEB cells are the target cells for mammary chemical carcinogenesis. Feeding butter fat CLA to rats during the time of pubescent mammary gland development reduced mammary epithelial mass by 22%, decreased the size of the TEB population by 30%, suppressed the proliferation of TEB cells by 30% and inhibited mammary tumor yield by 53% (P < 0.05). Furthermore, all of the above variables responded with the same magnitude of change to both butter fat CLA and the mixture of CLA isomers at the level of CLA (0.8%) present in the diet. Interestingly, there appeared to be some selectivity in the uptake or incorporation of c9,t11-CLA over t10,c12-CLA in the tissues of rats given the mixture of CLA isomers. Rats consuming the CLA-enriched butter fat also consistently accumulated more total CLA in the mammary gland and other tissues (four- to sixfold increases) compared with those consuming free fatty acid CLA (threefold increases) at the same dietary level of intake. We hypothesize that the availability of vaccenic acid (t11-18:1) in butter fat may serve as the precursor for the endogenous synthesis of CLA via the Delta9-desaturase reaction. Further studies will be conducted to investigate other attributes of this novel dairy product.

Effect of increased vegetable and fruit consumption on markers of oxidative cellular damage

The goal of this study was to test the hypothesis that increased consumption of vegetables and fruit would reduce markers of oxidative cellular damage that can be assessed in blood or urine. Twenty-eight women participated in a 14 day dietary intervention. The primary end-points assessed were: 8-hydroxydeoxyguanosine (8-OHdG) in DNA isolated from peripheral lymphocytes, determined by HPLC with electrochemical detection; 8-OHdG excreted in urine, measured by ELISA; malondialdehyde (MDA) in urine, measured by fluorimetric detection following derivatization with thiobarituric acid and separation via HPLC; urinary 8-isoprostane F-2alpha (8-EPG) detected by ELISA. Pre- and post-intervention plasma levels of selected carotenoids were determined by HPLC. Subjects were free living and consumed a completely defined recipe-based diet that increased their average daily consumption of vegetables and fruit from 5.8 servings at baseline to 12.0 servings throughout the intervention. Overall, the level of 8-OHdG in DNA isolated from lymphocytes and in urine and the level of 8-EPG in urine were reduced by the intervention, whereas urine concentrations of MDA were minimally affected. The reduction in lymphocyte 8-OHdG was greater in magnitude (32 versus 5%) in individuals with lower average pre-intervention levels of plasma alpha-carotene (56 ng/ml) than in individuals with higher average pre-intervention plasma levels of alpha-carotene (148 ng/ml). The results of this study indicate that consumption of a diet that significantly increased vegetable and fruit intake from a diverse number of botanical families resulted in significant reductions in markers of oxidative cellular damage to DNA and lipids.

Effects of methylselenocysteine on PKC activity, cdk2 phosphorylation and gadd gene expression in synchronized mouse mammary epithelial tumor cells

Methylselenocysteine (MSC), an organic selenium compound is an effective chemopreventive agent against mammary cell growth both in vivo and in vitro but its mechanism of action is still not understood. We have previously demonstrated that MSC is able to inhibit growth in a synchronized TM6 mouse mammary epithelial tumor cell line at 16 h time point followed by apoptosis at 48 h. The decrease in cdk2 kinase activity was coincident with prolonged arrest of cells in S-phase. The present set of experiments showed that cdk2 phosphorylation was reduced by 72% in the MSC-treated cells at 16 h time point. Expression for gadd34, 45 and 153 was elevated 2.5 to 7 fold following MSC treatment only after 16 h time point. In order to investigate a possible upstream target for MSC, we analyzed protein kinase C (PKC) in this model. Total PKC activity was reduced in TM6 cells by MSC (50 microM) within 30 min of treatment, both in cytosolic (55.4 and 77.6%) and membrane (35.2 and 34.1%) fractions for calcium-dependent and independent PKCs, respectively. PMA significantly elevated the PKC activity in membrane fraction (P < 0.01) and MSC inhibited this activation by more than 57%. The effect of MSC was selenium specific as selenomethionine and sulfurmethyl-L-cysteine (SMC) did not alter PKC activity either in cytosolic or membrane fraction. Immunoblot analysis showed that PKC-alpha was translocated to the membrane by PMA and MSC did not alter this translocation. PKC-delta was faintly detectable in membrane fractions of control and MSC-treated cells. MSC treatment slightly reduced levels of PKC-e (in cytosolic and membrane fractions) and PKC-zeta (cytosolic fractions). The data presented herein suggest that PKC is a potential upstream target for MSC that may trigger one or all of the downstream effects; i.e. the decrease of cdk2 kinase activity, decreased DNA synthesis, elevation of gadd gene expression and finally apoptosis.

Effect of energy restriction on tissue size regulation during chemically induced mammary carcinogenesis

Energy restriction (ER) has documented beneficial effects on numerous diseases including cancer, yet the mechanism(s) that accounts for these effects is unknown. Experiments were designed to determine the effect of ER: (i) on the growth and development of the mammary gland; (ii) on the growth of carcinomas induced in the mammary gland by treatment with 1-methyl-1-nitrosourea (MNU); (iii) on rates of cell proliferation and apoptosis in pre-malignant and malignant mammary lesions. Mammary carcinogenesis was induced in female Sprague-Dawley rats by the i.p. administration of MNU (50 mg MNU/kg body wt) at 21 days of age. Rats were randomized to one of four dietary treatment groups: ad libitum fed or restriction of calorie intake to 90, 80 or 60% of ad libitum intake. ER reduced the ductal extension of the mammary gland into the fat pad in proportion to its effect on growth measured as body weight, however, the reduction in ductal branching, breast density and carcinoma volume by ER was greater than its effect on body weight. An animal's breast density was predictive of its carcinogenic response, irrespective of the level of ER imposed. While ER inhibited cell proliferation and induced apoptosis in pre-malignant and malignant mammary gland lesions, the magnitude of these effects make it unlikely that they fully account for the protective effects of ER against mammary carcinogenesis.

Chemoprevention of mammary cancer with Se-allylselenocysteine and other selenoamino acids in the rat

The present study examined the mammary cancer chemopreventive activity of Se-methylselenocysteine, Se-propylselenocysteine and Se-allylselenocysteine in the rat methylnitrosourea (MNU) model. Each compound was supplemented in the diet at a level of 2 ppm Se for the entire duration of the experiment after MNU dosing. Se-Allylselenocysteine was the most active and caused a reduction in total tumor yield by 86%. Se-Methylselenocyteine and Se-propylselenocysteine were similar but less effective, and both produced a decrease of about 50% in tumorigenesis. All three compounds were very well absorbed through the gastrointestinal tract. However, more selenium was excreted in urine after gavaging with Se-propylselenocysteine or Se-allylselenocysteine compared with Se-methylselenocysteine. Analysis of selenium in the mammary gland and other organs showed that tissue selenium levels did not appear to be correlated with differences in chemopreventive activity. A lyase activity capable of catalyzing scission of the Se-alkyl group from the remainder of the amino acid was demonstrated. This activity was found to be high in liver and kidney, but relatively low in mammary gland and intestine. Minimal variations in enzyme activity towards each of the substrates were observed. Our results support the concept that Se-alkylselenoamino acids could be used as precursors for delivering the Se-alkyl moiety and that intrinsic chemical differences in the Se-alkyl substituent of the test compounds are likely to be important determinants of their biological effects.

The management of post-operative nausea and vomiting

Despite the advent of new technology and pharmacological agents, post-operative nausea and vomiting (PONV) continues to have an incidence of 20-30% today. Development of PONV can lead to serious complications such as aspiration, dehydration, electrolyte disturbances and disruption of the surgical site. PONV leads to increased cost of treatment, and may be associated with increased anxiety, dissatisfaction with the surgical experience and anticipatory nausea in the future. The mechanisms of PONV are examined with associated risk factors. A review of the literature of PONV management is included covering pharmacological, dietary and behavioural interventions; culminating in the development of assessment and management guidelines and identification of areas for further study.

Effect of energy restriction on the expression of cyclin D1 and p27 during premalignant and malignant stages of chemically induced mammary carcinogenesis

The restriction of energy intake has a profound inhibitory effect on carcinogenesis, yet the mechanism or mechanisms that account for this effect are unknown. In this experiment, the hypothesis tested was that energy restriction upregulates the expression of p27/kip1, a gene product associated with cell-cycle growth arrest, while downregulating cyclin D1, a protein that combines with cyclin-dependent kinases to promote phosphorylation of retinoblastoma protein and the progression of cells through the cell cycle. We studied levels of these proteins in uninvolved mammary epithelial cells and in mammary intraductal proliferations, ductal carcinomas in situ, and adenocarcinomas induced in response to administration of 1-methyl-1-nitrosourea in animals fed either ad libitum or 90%, 80%, or 60% of ad libitum intake. Protein levels were evaluated immunohistochemically by using computer-assisted image analysis to quantify differences in protein expression among treatment groups. The expression of p27 increased and the expression of cyclin D1 decreased dose-dependently in response to energy restriction. The effect was greater on p27 than on cyclin D1. The hypothesis proposed is that energy restriction inhibits carcinogenesis by arresting cell-cycle progression by regulating p27/kip1.

Temporal sequence of mammary intraductal proliferations, ductal carcinomas in situ and adenocarcinomas induced by 1-methyl-1-nitrosourea in rats

An experimental model for mammary carcinogenesis has been described in which intraductal proliferations, ductal carcinomas in situ and adenocarcinomas can be readily detected and the frequency of their occurrence quantified. The objective of the experiment reported in this study was to determine the latency period between carcinogen administration and the occurrence of each of these types of lesion. A total of 150 female Sprague-Dawley rats were injected i.p. with 50 mg 1-methyl-1-nitrosourea (MNU)/kg body wt at 21 days of age. Groups of 30 rats each were killed at 7, 14, 21, 28 and 35 days post-carcinogen. Mammary intraductal proliferations were the first detected lesions and were observed in 20% of the animals at 14 days following carcinogen administration. At 21 days post-carcinogen ductal carcinomas in situ and adenocarcinomas were observed. The number of each type of lesion increased with time post-carcinogen, but the temporal pattern of occurrence was different among lesion types. The pattern of lesion occurrence was consistent with intraductal proliferations being a precursor lesion for ductal carcinomas in situ and adenocarcinomas. Furthermore, the data imply that ductal carcinomas in situ represent one pathway of morphological progression by which intraductal proliferations evolve into invasive carcinomas, but that this lesion type, as currently defined histologically, may not be an obligatory intermediate in morphologic progression. These findings are consistent with emerging evidence of multiple but distinct pathogenetic pathways leading to mammary carcinomas that display different morphological patterns and biological activities.

Effect of corticosterone administration on mammary gland development and p27 expression and their relationship to the effects of energy restriction on mammary carcinogenesis

The inhibitory activity against mammary carcinogenesis mediated by energy restriction is accompanied by a reduction in the degree of mammary ductal branching, and an increase in adrenal cortical activity. Levels of p27/kip1 protein, a gene product associated with cell cycle growth arrest, have also been shown to be elevated in mammary epithelium and in mammary lesions of energy-restricted animals. Based on these data we have proposed that increased secretion of adrenal cortical steroids accounts, in part, for the effects of energy restriction. In this experiment the hypothesis tested was that corticosterone administration would mimic the effects of energy restriction, both on mammary gland development and on levels of p27 protein in mammary ductal epithelium. To test this hypothesis corticosterone was fed to female rats for 4 weeks. Dietary corticosterone increased serum and urinary corticosterone levels in a dose-dependent manner (P < 0.01). The effects of corticosterone treatment on mammary gland development were analyzed digitally; p27 protein was detected immunohistochemically. The ductal extension and branching of the mammary gland were reduced in a dose-dependent manner by corticosterone treatment (P < 0.05); however, the magnitude of the effect was greater on ductal branching. Overall, increasing dietary corticosterone reduced the total volume of mammary epithelium in a dose-dependent manner, an effect that remained even after adjustments for differences among animals in body mass. Consistent with this effect, the amount of p27 protein present in ductal mammary epithelial cells increased dose-dependently in response to increasing corticosterone administration (P < 0.01). The hypothesis is proposed that dietary administration of corticosterone may imitate the effects of energy restriction on mammary carcinogenesis by regulation of mammary tissue size homeostasis via p27/kip1 mediated arrest of cell cycle progression.

X-radiation induces 8-hydroxy-2'-deoxyguanosine formation in vivo in rat mammary gland DNA

Ionizing radiation is a carcinogen that induces oxidative DNA damage. 8-Hydroxy-2'-deoxyguanosine (8-OHdG) is a relatively abundant, mutagenic lesion that is widely regarded as a reliable index of oxidative DNA damage. The purpose of this study was to examine the effects of X-radiation on levels of 8-OHdG in the context of an experimental model for breast cancer in which chronic radiation exposure has been shown to be carcinogenic in Sprague-Dawley rats. A secondary objective of this study was to determine if the use of phenol during DNA isolation affected the concentration of 8-OHdG subsequently measured. Our results indicate that a profoundly carcinogenic dose of radiation induced a small but significant increase in 8-OHdG concentration in mammary gland DNA, and that the use of a phenol-based versus a salt-based method of DNA isolation had no significant impact on the levels of 8-OHdG detected in either control or irradiated tissue.

Microsatellite instability in an animal model of mammary carcinogenesis

Alterations in the length of simple repetitive genomic sequences (microsatellite instability, MSI) may characterize a distinct mechanism of mammary carcinogenesis. In order to investigate whether MSI is associated with chemically-induced mammary carcinogenesis in the rat, 30 microdissected mammary carcinomas were analyzed using 27 different microsatellite markers from chromosomes 1, 3, 5, 7 and 8. DNA was extracted from rat mammary cancer and adjoining microscopically normal tissues from the same slide, amplified by PCR, using different polymorphic DNA markers and the reaction products were analyzed for microsatellite instability. The results of this study indicate that 30% of cases (9 out of 30) showed microsatellite instability at a minimum of 1 locus. Three cases (out of 30) showed microsatellite instability at only three loci or less, called MSI-L (low frequency MSI). Six cases (out of 30) showed MSI at four loci or more, called MSI-H (high frequency MSI). Six cases showed MSI at D5Mit11 and D5Mgh3 loci, five cases showed MSI at D1Mit14, D1Mgh6, D5Mgh5 and D8Mgh10 loci, four cases had MSI at D1Mgh2, and D3Mgh7 loci, three cases had MSI at D3Mit3, D3Mgh5, D7Mgh1 loci, two cases had MSI at D7Mit11 locus and one case had MSI at D3Mgh9 locus. The results of these experiments suggest that MSI may be an important etiological event in the pathophysiology of mammary carcinogenesis.

Ovarian hormone dependence of pre-malignant and malignant mammary gland lesions induced in pre-pubertal rats by 1-methyl-1-nitrosourea

The experiments reported in this study were designed to examine the question of whether a mammary epithelial cell's independence from hormonal requirements is established at the time of carcinogenic initiation, or whether the emergence of hormone independence is associated with the process of tumor progression. A newly developed rat model of mammary carcinogenesis was used in which the latency period to lesion detection is very short and in which the frequencies of both pre-malignant and malignant mammary lesions can be quantified. Two experiments were conducted in Sprague-Dawley rats injected with 50 mg MNU/kg body wt at 21 days of age. In the first experiment 47 animals were ovariectomized after the detection of a mammary tumor of palpable size. Forty-six of the 47 tumors assessed, all of which were subsequently classified as mammary gland adenocarcinomas, regressed to <50% of their initial volume within 14 days of bilateral ovariectomy. However, both pre-malignant and malignant mammary gland lesions were observed when animals were killed. In Experiment 2 a total of 60 rats were ovariectomized 7 days after MNU was injected. At 35 days post carcinogen ovariectomized animals had a higher incidence of intraductal proliferations than sham-operated controls (P = 0.03); there was no effect of ovariectomy on the incidence of ductal carcinoma in situ or carcinoma. The multiplicity of intraductal proliferations was increased by 58% in ovariectomized rats (P = 0.12), but the number of mammary carcinoma per rat was reduced (3.8 vs. 1.57, P = 0.02). These data are consistent with the hypotheses that the progression of pre-malignant to malignant lesions is inhibited in the mammary gland by ovariectomy and that the hormone independent phenotype can be conferred at the time of carcinogenic initiation.

Pathogenic characterization of 1-methyl-1-nitrosourea-induced mammary carcinomas in the rat

The induction of mammary carcinogenesis in the rat by 1-methyl-1-nitrosourea (MNU) is widely used in experimental breast cancer research. In the experiments reported, the Ha-ras codon 12 (ras12) mutation (GGA-->GAA) was used as a molecular marker to address issues of the clonality of carcinomas induced, pathogenetic independence among multiple carcinomas within the same animal and topographic distribution of mutant ras12 carcinomas in different mammary gland chains. In order to determine whether the frequently observed morphologically distinguishable lobules within carcinomas originate from the coalescence of independent lesions or whether cancerous cells within a carcinoma share a common origin, 44 randomly selected MNU-induced mammary carcinomas were genotyped for two to four lobules each for the ras12 mutation. A total of 43 carcinomas out of 44 (97.7%) had concordant ras12 genotypes among the multiple sites within each tumor, which is consistent with the latter possibility. Next, it was observed that as carcinoma multiplicity increased, the discordance rate of ras12 genotypes among multiple carcinomas within the same animal increased in a manner that was in excellent agreement with the expected discordance rate based on an assumption of no pathogenetic association among carcinomas. Furthermore, a significant difference was observed in the occurrence of mutant ras12 carcinomas between the cervical-thoracic and the abdominal-inguinal mammary glands in that three times as many carcinomas were mutant in the former as in the latter glands, whereas the occurrence of wild-type carcinomas was approximately the same in both regions. Taken together, the data are consistent with (i) carcinomas induced by MNU and detected by palpation are monoclonal in origin, (ii) independently-initiated cells emerge as distinct mammary carcinomas in the same animal, and (iii) the anatomical location of the gland may affect the prevalence of mammary carcinomas that harbor a mutant ras12.

Cytostasis and cancer chemoprevention: investigating the action of triphenylselenonium chloride in in vivo models of mammary carcinogenesis

In this study, specific aspects of the cancer chemopreventive activity of triphenylselenonium chloride were investigated. The research was carried out in three in vivo models of MNU-induced mammary carcinogenesis in rats: a) a newly developed model characterized by the rapid but time-dependent appearance of intraductal proliferations, ductal carcinoma in situ and adenocarcinomas; b) a conventional model which took 5 months for full expression of all palpable tumors; and c) a late stage model which used tumor-bearing rats as the target population. Our work indicated that a) triphenylselenonium was able to delay the progression of premalignant to malignant lesions; b) chronic exposure to triphenylselenonium was required to sustain its cancer inhibitory activity; and c) triphenylselenonium failed to induce regression of established mammary carcinomas or suppress the emergence of new tumors when it was given at the late stage of carcinogenesis. These findings highlight the importance of understanding the range of activity of a given chemopreventive agent in order to maximize the probability of a successful outcome in the design of any future intervention trial.

Telomerase activity in the normal and neoplastic rat mammary gland

The 1-methyl-1-nitrosourea-induced rat mammary tumor model system is well studied, reproducible, and widely used. We have investigated whether these tumors possess higher telomerase activity than normal mammary tissue. Using the telomeric repeat amplification protocol assay, we found significantly higher telomerase activity in 36 mammary carcinomas than in 72 mammary glands of virgin rats. The level of telomerase activity in virgin rats was unaffected by strain, age, stage of the estrous cycle, or ovariectomy. However, mammary glands obtained from pregnant rats exhibited telomerase activity comparable to that found in the tumors, possibly reflecting the high epithelial content of these tissues. Indeed, isolated epithelial cells from virgin and pregnant mammary glands and from carcinomas had similar telomerase activities. Thus, telomerase activity is constitutive in the rat mammary epithelium and is not a unique characteristic of malignant transformation in this tissue. These results underscore the importance of attributing biochemical properties to specific cell types in a tissue, a situation not paralleled in the interpretation of data from in vitro models.

Cyclic food restriction, insulin and mammary cell proliferation in the rat

We reported recently that weight cycling significantly increased the incidence of mammary cancer in virgin female rats that were pretreated with N-methyl-N-nitrosourea. The present study investigated the effect of weight cycling on mammary epithelial cell proliferation and its relationship to changes in plasma insulin, estrogen, progesterone and urinary corticosterone in 30 female virgin Sprague-Dawley rats. Animals were fed a modified AIN-76A diet containing 24.6% corn oil by weight. Weight-cycled (WC) rats were food restricted daily by either 33% or 50% of non-restricted controls for 1 week followed by 3 weeks compensatory refeeding and weight recovery over 18 weeks or 4.5 weight cycles. WC rats consumed 6-10% less food than controls (P = 0.01) but showed a 71-89% greater efficiency of food utilization for growth (P < 0.0001) than controls. There were no differences in total weight gain during treatment. Mammary lobuloalveolar and ductal cell proliferation of WC rats, measured by 5-bromo-2'deoxyuridine labelling, increased in a dose-response fashion, P = 0.03, P = 0.06 respectively in comparison to controls. Energy and substrate utilization measured by indirect calorimetry indicated WC animals expended less energy (P = 0.005) and utilized less glucose (P = 0.0001) and protein (P = 0.006) during restriction, and less lipid during recovery (P = 0.05) than controls. There were no significant differences in hormone levels between groups. Multiple regression analysis with plasma insulin, estrogen, progesterone and urinary corticosterone as independent variables (r = 0.947, r2 = 0.897, P = 0.003) showed that plasma insulin was the only significant predictor (P < 0.01) of mammary cell proliferation. In accord with this observation, tyrosine-phosphorylated activation of insulin receptor substrate-1, detected by immunoprecipitation and Western immunoblot analysis in mammary tumors of WC rats from our previous study, was 3-5 times greater than in non-restricted controls (P < 0.01). Present findings suggest that weight cycling in rats increases risk of breast cancer development via insulin stimulated mammary cell proliferation.

Effects of physical activity and exercise on experimentally-induced mammary carcinogenesis

Physical activity is defined as skeletal muscle contraction resulting in a quantifiable expenditure of energy, whereas exercise is a specific type of physical activity in which planned, structured, and repetitive bodily movement is done to improve or maintain one or more components of physical fitness. The focus of laboratory studies of the physical activity-breast cancer hypothesis has been on evaluating how various types of physical activity including exercise affect the process of mammary carcinogenesis. A key objective has been the evaluation of the characteristics of physical activity, i.e. intensity, duration, and frequency, required to confer protection against experimentally-induced breast cancer. The results of those studies indicate that exercise rather than physical activity can exert a greater inhibitory effect against experimentally-induced breast cancer, and that the duration of exercise may not be as important as its intensity. This finding differs from evidence that other health benefits attributed to physical activity are proportional to the total amount of activity rather than the manner in which it is obtained. In this review criteria are defined for categorizing laboratory studies into those that investigated the effects of physical activity versus exercise on experimentally-induced mammary carcinogenesis, and the literature is reinterpreted in this context.

Gene expression changes associated with chemically induced rat mammary carcinogenesis

Experimentally induced models of breast carcinogenesis in the rat are widely used for studying the biology of breast cancer and for developing and evaluating cancer prevention and control strategies. However, very little is known about gene expression changes that are associated with experimentally induced mammary carcinogenesis. This paper reports the identification, by differential display of mRNA and molecular cloning, of seven cDNA fragments of gene transcripts overexpressed in mammary carcinomas induced by 1-methyl-1-nitrosourea. These genes included the rat homologues of human galectin-7 gene, the human/mouse melanoma inhibitory activity/bovine chondrocyte-derived retinoic acid sensitive protein gene, the mouse stearoyl-CoA desaturase-2 gene, and the mouse endo B cytokeratin/human cytokeratin-18 gene. Although each of these genes has been implicated in some aspect of carcinogenesis in other organs, this paper is the first report of their overexpression in chemically induced mammary carcinomas. Two previously uncharacterized gene transcripts were also identified. A comparison of the expression levels of several genes in mammary carcinomas with those in the normal mammary gland tissue of virgin rats, mid-stage pregnant rats, and of day 1 postpartum lactating dams indicated that the overexpression of several genes observed in mammary carcinomas could not be accounted for by either a difference in the mammary epithelial content between mammary carcinoma and normal mammary tissue or by mammary epithelium-specific proliferation associated with pregnancy. Several genes were also overexpressed in rat mammary carcinomas induced by 7,12-dimethylbenz[a]anthracene but not in azoxymethane-induced rat colon adenocarcinomas. The genes identified in this study may therefore represent mammary carcinoma-specific molecular markers that may be helpful in investigations of mammary carcinogenesis and its prevention.

Triphenylselenonium and diphenylselenide in cancer chemoprevention: comparative studies of anticarcinogenic efficacy, tissue selenium levels and excretion profile

The objectives of the present study were to evaluate the cancer chemopreventive activity of triphenylselenonium chloride and diphenylselenide and to investigate the pharmacology of these two compounds with respect to their tissue accumulation and excretion profile. Although both phenyl selenide derivatives are related to each other structurally, they differ substantially in their intrinsic chemical properties. Triphenylselenonium is positively charged and amphiphilic, while diphenylselenide is uncharged and lipophilic. With the use of either the DMBA- or MNU-induced mammary tumor model in rats, triphenylselenonium was found to have superior chemopreventive efficacy compared to diphenylselenide. Both reagents were present at 30 ppm Se in the diet. At the time of sacrifice (22 weeks post-carcinogen), triphenylselenonium produced only minimal accumulation of selenium in the liver, kidney, mammary gland and plasma. In contrast, diphenylselenide caused a 2- to 3-fold elevation in selenium concentration depending on the tissue examined. Thus even though diphenylselenide was able to increase total selenium in tissues, it was less active in cancer protection. Fecal excretion following a single oral dose of triphenylselenonium (equal to the amount consumed in 1 day by an animal fed a diet containing 30 ppm Se) was approximately 78% and 8% of the dose during the first and second day, respectively, suggesting that the bulk of the dose was not absorbed. With diphenylselenide, fecal excretion was about 6% and 30% of the dose during the first and second day, and about 20% of the dose was excreted in the urine in each of the 2 days. This observation suggests that a large proportion of the diphenylselenide dose was absorbed and that urinary excretion was a major route of elimination for diphenylselenide once it was absorbed. Further studies are needed to clarify the basis for the differential effects of these phenyl selenide derivatives.