Biomedical subjects

Andrea M Mastro

Publications and source records attributed to Andrea M Mastro.

16 recordsLinked to original sources

PubMed2006

Chronic resistance training in women potentiates growth hormone in vivo bioactivity: characterization of molecular mass variants.

This investigation determined the influence of acute and chronic resistance exercise on responses of growth hormone (GH) molecular variants in women. Seventy-four healthy young women (23 +/- 3 yr, 167 +/- 7 cm, 63.8 +/- 9.3 kg, 26.3 +/- 4.0% body fat) performed an acute bout of resistance exercise (6 sets of 10 repetition maximum squat). Blood samples were obtained pre- and postexercise. Resulting plasma was fractionated by molecular mass (fraction A, >60 kDa; fraction B, 30-60 kDa; and fraction C, <30 kDa) using chromatography. Fractionated and unfractionated (UF) plasma was then assayed for GH using three different detection systems (monoclonal immunoassay, polyclonal immunoassay, and rat tibial line in vivo bioassay). Subjects were then matched and randomly placed into one of four resistance exercise training groups or a control group for 24 wk. All experimental procedures were repeated on completion of the 24-wk resistance training programs. After acute exercise, immunoassays showed consistent increases in UF GH samples and fractions B and C; increases in fraction A using immunoassay were seen only in the monoclonal assay. No consistent changes in bioactive GH were found following acute exercise. Conversely, chronic exercise induced no consistent changes in immunoassayable GH of various molecular masses, whereas, in general, bioassayable GH increased. In summary, although acute exercise increased only immunoactive GH, chronic physical training increased the biological activity of circulating GH molecular variants. Increased bioactive GH was observed across all fractions and training regimens, suggesting that chronic resistance exercise increased a spectrum of GH molecules that may be necessary for the multitude of somatogenic and metabolic actions of GH.

Adult↗

PubMed2006

Kinetics of metastatic breast cancer cell trafficking in bone.

PURPOSE: In vivo studies have focused on the latter stages of the bone metastatic process (osteolysis), whereas little is known about earlier events, e.g., arrival, localization, and initial colonization. Defining these initial steps may potentially identify the critical points susceptible to therapeutic intervention. EXPERIMENTAL DESIGN: MDA-MB-435 human breast cancer cells engineered with green fluorescent protein were injected into the cardiac left ventricle of athymic mice. Femurs were analyzed by fluorescence microscopy, immunohistochemistry, real-time PCR, flow cytometry, and histomorphometry at times ranging from 1 hour to 6 weeks. RESULTS: Single cells were found in distal metaphyses at 1 hour postinjection and remained as single cells up to 72 hours. Diaphyseal arrest occurred rarely and few cells remained there after 24 hours. At 1 week, numerous foci (2-10 cells) were observed, mostly adjacent to osteoblast-like cells. By 2 weeks, fewer but larger foci (> or =50 cells) were seen. Most bones had a single large mass at 4 weeks (originating from a colony or coalescing foci) which extended into the diaphysis by 4 to 6 weeks. Little change (<20%) in osteoblast or osteoclast numbers was observed at 2 weeks, but at 4 to 6 weeks, osteoblasts were dramatically reduced (8% of control), whereas osteoclasts were reduced modestly (to approximately 60% of control). CONCLUSIONS: Early arrest in metaphysis and minimal retention in diaphysis highlight the importance of the local milieu in determining metastatic potential. These results extend the Seed and Soil hypothesis by demonstrating both intertissue and intratissue differences governing metastatic location. Ours is the first in vivo evidence that tumor cells influence not only osteoclasts, as widely believed, but also eliminate functional osteoblasts, thereby restructuring the bone microenvironment to favor osteolysis. The data may also explain why patients receiving bisphosphonates fail to heal bone despite inhibiting resorption, implying that concurrent strategies that restore osteoblast function are needed to effectively treat osteolytic bone metastases.

Animals↗

PubMed2006

Proenkephalin peptide F immunoreactivity in different circulatory biocompartments after exercise.

This study was the first study to examine the three circulatory biocompartments (plasma, white blood cell layer (WBC) and red blood cell layer (RBC)) and determine PF concentrations before and after exercise. Proenkephalin peptide F (PF) is an enkephalin-containing peptide found predominantly within the adrenal medulla. PF is co-packaged with epinephrine, and both can be co-secreted in response to similar stimuli. PF and epinephrine have shown immunomodulating properties. Ten healthy resistance trained men performed six sets of 10 RM squats with 2 min rest periods between sets and 10 healthy active men were matched and served as resting controls. Blood samples were obtained pre-exercise, immediately post-exercise and 15 min post-exercise and were analyzed for lactate, cortisol, epinephrine and biocompartmentalized PF. There was no change in resting control values measured across time within respective PF biocompartments and endocrine profile, indicating stability and technique validity of peptide F across the time period measured. As expected, the acute resistance exercise protocol caused an increase in lactate at 15 min post-exercise. Circulating epinephrine increased immediately post-exercise and returned to baseline during 15 min into recovery. Plasma PF increased immediate post-exercise and 15 min post-exercise, while WBC-PF and RBC-PF only increased at 15 min into recovery. For all time points tested, resting and exercise WBC-PF and RBC-PF concentrations were lower than plasma PF thus indicating a concentration difference across the three different biocompartments within the same blood sample. The presence of PF within all three biocompartments of whole blood may indicate the potential for biological transport and interactions with other cells in other biocompartments of the blood.

Adult↗

PubMed2005

Cytokines secreted by bone-metastatic breast cancer cells alter the expression pattern of f-actin and reduce focal adhesion plaques in osteoblasts through PI3K.

Breast cancer frequently metastasizes to bone, resulting in osteolytic lesions. These lesions, formed by activated osteoclasts, cause pain, an increased susceptibility to fractures, and hypercalcemia. It has been shown that breast cancer cells communicate with osteoblasts and subsequently stimulate osteoclast activity; however, little research has focused on understanding the interaction between breast cancer cells and osteoblasts. We recently reported that conditioned medium from MDA-MB-231 breast cancer cells inhibited the differentiation of MC3T3-E1 osteoblasts through the secretion of transforming growth factor beta (TGFbeta). In addition, the breast cancer conditioned medium altered MC3T3-E1 morphology, the pattern of actin stress fibers, and reduced focal adhesion plaques. In the current study, we identified the mechanism used by MDA-MB-231 cells to cause these effects. When MC3T3-E1 osteoblasts were cultured with MDA-MB-231 conditioned medium preincubated with neutralizing antibodies to platelet derived growth factor (PDGF), insulin-like growth factorII (IGFII), and TGFbeta, focal adhesion plaques and actin stress fiber formation were restored. These cytokines were further found to signal through PI3Kinase and Rac. In conclusion, TGFbeta, PDGF, and IGFII might be good therapeutic targets for treating breast cancer-induced osteolytic lesions.

Actins↗

PubMed2005

Nutritional status predicts primary subclasses of T cells and the lymphocyte proliferation response in healthy older women.

Aging is often associated with a dysregulation in immune function, particularly in T-cell responses, even in the healthy elderly. Adequate nutrition is important for optimal immune function. The literature on the relation of nutritional status with immune function in the elderly offers mixed findings. Because several nutrients can influence immune response, and there are interactions among nutrients, examining the association of various nutrients measured simultaneously with tests of immune function is important. We examined the association of protein, iron, zinc, vitamin B-12, and folic acid with tests of acquired immunity in healthy older women (76.7 +/- 7.0 y; n = 130). Discriminant analysis was used to identify the predictive subset of nutrients that could correctly classify subjects into the lowest or highest quartiles (< or =25th or >75th percentile) on various immune function tests (T cells and subsets and lymphocyte proliferation in response to culture with mitogens). Protein and iron status variables were identified in the predictive subset for all immune tests; in addition, zinc emerged in the predictive model for T cells and their subsets as well as for the proliferation response to concanavalin A. The probability of correctly classifying women into the lowest or highest quartiles of immune tests by the predictive subset of nutrition variables was high, i.e., 62.8-83.5% for T cells and their subsets, and 79.3-89.7% for the proliferation response to mitogens. In conclusion, protein, iron, and zinc were significant predictors of immune function in older women. Adequate status of these nutrients may help maintain immunity in older adults.

Aged↗

PubMed2005

Exercise and lymphocyte activation following chemotherapy for breast cancer.

PURPOSE: To determine whether exercise training would increase lymphocyte activation in patients with breast cancer following chemotherapy. Activation was determined by the presence of CD4(+)CD69(+) T-helper lymphocytes, mitogen-induced proliferation, and levels of cytokines produced by mitogen-stimulated lymphocytes and in the patients' plasma. METHODS: Patients with breast cancer (N = 28) who participated in a 6-month exercise program were compared with patients (N = 21) who did not exercise. Following chemotherapy, and 3 and 6 months later, patients underwent fitness evaluations and had blood drawn. The exercise program consisted of resistance training and aerobic activity at 60-75% functional capacity three times a week with a personal trainer. Immunochemistry and flow cytometry were used to measure the number of CD4(+)CD69(+) blood lymphocytes. Whole blood was stimulated with concanavalin A (ConA), phytohemagglutin (PHA), or pokeweed mitogen (PWM) to determine proliferation potential. Enzyme-linked immunosorbent assays (ELISA) were used to determine the concentration of interferon-gamma (IFN-gamma) and interleukin-6 (IL-6) in the culture medium of mitogen-stimulated lymphocytes as well as the plasma concentrations of IL-6, soluble IL-6 receptor, soluble gp130, and IFN-gamma. Analysis of groups across time was done using the Wilcoxon signed rank test, and comparisons of groups were done using the Mann-Whitney U test. RESULTS: The exercising patients showed increases in maximal oxygen uptake and upper body strength. This group also showed a greater percentage of CD4(+)CD69(+) cells and a greater level of tritiated thymidine incorporation (DNA synthesis) when stimulated with ConA, PHA, and PWM at the end of the intervention. Plasma and mitogen-stimulated IL-6 and IFN-gamma production were similar in both groups. CONCLUSION: Exercise may improve immune function by increasing lymphocyte activation in patients with breast cancer following treatment.

Adult↗

PubMed2004

Breast cancer cells induce osteoblast apoptosis: a possible contributor to bone degradation.

Breast cancer cells exhibit a predilection for metastasis to bone. There, the metastases usually bring about bone loss with accompanying pain and loss of function. One way that breast cancer cells disrupt the normal pattern of bone remodeling is by activating osteoclasts, the bone degrading cells. Nevertheless, targeting the osteoclasts does not cure the disease or result in bone repair. These observations indicate that osteoblast function also may be compromised. The objective of this study was to investigate the interaction of metastatic breast cancer cells with osteoblasts. Human metastatic breast cancer cells, MDA-MB-435 or MDA-MB-231, or their conditioned media were co-cultured with a human osteoblast line hFOB1.19. The breast cancer cells caused an increase in the prevalence of apoptotic osteoblasts. Apoptotic osteoblasts detected by the TUNEL assay or by caspase activity increased approximately two to fivefold. This increase was not seen with non-metastatic MDA-MB-468 cells. In an investigation of the mechanism, it was determined that the hFOB1.19 cells expressed fas and that fas was functional. Likewise the hFOB1.19 cells were susceptible to TNF-alpha, but this cytokine was not detected in the conditioned medium of the breast cancer cells. This study indicates that osteoblasts are the target of breast cancer cell-induced apoptosis, but fas/fas-ligand and TNF-alpha, two common initiators of cell death, are probably not involved in this aspect of the metastases/bone cell axis. There are several mechanisms that remain to be explored in order to determine how breast cancer cells bring about osteoblast apoptosis. Even though the specific initiator of apoptosis remains to be identified, the results of this study suggest that the mechanism is likely to be novel.

Apoptosis↗

PubMed2004

Metastatic breast cancer cells suppress osteoblast adhesion and differentiation.

Bone is a primary target for colonization of metastatic breast cancer cells. Once present, the breast cancer cells activate osteoclasts, thereby stimulating bone loss. Bone degradation is accompanied by pain and increased susceptibility to fractures. However, targeted inhibition of osteoclasts does not completely prevent lesion progression, nor does it heal the lesions. This suggests that breast cancer cells may also affect osteoblasts, cells that build bone. The focus of this study was to determine the ability of breast cancer cells to alter osteoblast function. MC3T3-E1 osteoblasts were cultured with conditioned medium from MDA-MB-231 breast cancer cells and subsequently assayed for changes in differentiation. Osteoblast differentiation was monitored by expression of osteocalcin, bone sialoprotein and alkaline phosphatase, and by mineralization. Osteoblasts cultured with MDA-MB-231 conditioned medium did not express these mature bone proteins, nor did they mineralize a matrix. Inhibition of osteoblast differentiation was found to be due to transforming growth factor beta present in MDA-MB-231 conditioned medium. Interestingly, breast cancer conditioned medium also altered cell adhesion. When osteoblasts were assayed for adhesion properties using interference reflection microscopy and scanning acoustic microscopy, there was a reduction in focal adhesion plaques and sites of detachment were clearly visible. F-actin was disassembled and punctate in osteoblasts cultured with MDA-MB-231 conditioned medium rather than organized in long stress fibers. Taken together, these observations suggest that metastatic breast cancer cells alter osteoblast adhesion and prevent differentiation. These affects could account for the continued loss of bone after osteoclast inhibition in patients with bone-metastatic breast cancer.

Alkaline Phosphatase↗

PubMed2004

A small molecule antagonist of the alpha(v)beta3 integrin suppresses MDA-MB-435 skeletal metastasis.

INTRODUCTION: Breast cancer is one of the most common malignancies affecting women in the United States and Europe. Approximately three out of every four women with breast cancer develop metastases in bone which, in turn, diminishes quality of life. The alpha(v)beta3 integrin has previously been implicated in multiple aspects of tumor progression, metastasis and osteoclast bone resorption. Therefore, we hypothesized that the alpha(v)beta3-selective inhibitor, S247, would decrease the development of osteolytic breast cancer metastases. MATERIALS AND METHODS: Cells were treated in vitro with S247 and assessed for viability and adhesion to matrix components. Athymic mice received intracardiac (left ventricle) injections of human MDA-MB-435 breast carcinoma cells expressing enhanced green-fluorescent protein. Mice were treated with vehicle (saline) or S247 (1, 10, or 100 mg/kg/d) using osmotic pumps beginning either one week before or one week after tumor cell inoculation. Bones were removed and examined by fluorescence microscopy and histology. The location and size of metastases were recorded. RESULTS AND CONCLUSIONS: IC50 for S247 adhesion to alpha(v)beta3 or alpha(IIB)beta3a substrates was 0.2 nM vs. 244 nM, respectively. Likewise, S247 was not toxic at doses up to 1000 microM. However, osteoclast cultures treated with S247 exhibited marked morphological changes and impaired formation of the actin sealing zone. When S247 was administered prior to tumor cells, there was a significant, dose-dependent reduction (25-50% of vehicle-only-treated mice; P = 0.002) in osseous metastasis. Mice receiving S247 after tumor cell inoculation also developed fewer bone metastases, but the difference was not statistically significant. These data suggest that, in the MDA-MB-435 model, the alpha(v)beta3 integrin plays an important role in early events (e.g., arrest of tumor cells) in bone metastasis. Furthermore, the data suggest that alpha(v)beta3 inhibitors may be useful in the treatment and/or prevention of breast cancer metastases in bone.

Actins↗

PubMed2004

Responses of plasma proenkephalin peptide F in rats following 14 days of spaceflight.

INTRODUCTION: . Proenkephalin peptide F [107-140] is related to the enhancement of immune function, while microgravity has been shown to cause immuno-suppression. We investigated the physiological response of proenkephalin peptide F to microgravity. METHODS: There were 12 Fischer 344 female rats, ovariectomized at 10.5 wk of age, used to determine plasma concentrations of peptide F in response to a 14-d flight aboard the Columbia Space Shuttle mission STS-62. There were 36 other such rats that served as ground-based controls to separate the effects of microgravity from those of thermal stress, flight stress, and crowded habitats. Control groups of 12 rats each were kept under the following conditions: 1) 22 degrees C vivarium, 2) 28 degrees C vivarium, and 3) variable (Var) to mimic flight. The flight and control groups were housed in animal enclosure modules 21 d prior to flight and for the duration of the study. The rats were sacrificed within 4-5 h after landing, at which time blood samples were obtained. RESULTS: Body weights were obtained prior to sacrifice; mean values were flight, 199 g; 22 degrees C, 193 g; 28 degrees C, 192 g; and Var, 194 g. The flight group produced a significantly greater (p < or = 0.05) level of plasma peptide F (0.056 pmol x ml(-1)) compared with the controls (0.016, 0.022, and 0.016 pmol x ml(-1) for 22 degrees C, 28 degrees C, and Var, respectively). Flight animals demonstrated higher corticosterone concentrations and reduced T and B cell splenocyte counts than controls. CONCLUSIONS: These data indicate that the increases in proenkephalin peptide F observed with exposure to microgravity may present an adrenal-medullary response to cope with the decreased immune function and increased stress experienced during spaceflight and landing.

Animals↗

PubMed2003

Inter- and intra-individual variation in tests of cell-mediated immunity in young and old women.

Exploring means to maintain or improve immunity in older persons has been receiving attention. To establish relationships between immune function and variables of interest, it is important to determine these variables accurately and precisely. Precision relates to the degree of variation in the laboratory test. The nature and magnitude of variability in tests of immune function has not been described extensively. We examined inter- and intra-individual variation in tests of cell-mediated immunity (CMI) in generally healthy and well-nourished young (20-40 years; n=15) and old (60-80 years; n=15) women. Subjects provided blood samples on 2 days within a week to determine leukocyte subsets, T-cell proliferation response to phytohemagglutinin A and concanavalin A, and interleukin (IL)-1beta, IL-2 and IL-6 production by stimulated mononuclear cells. Intra-individual variation was partitioned into day-to-day biological and analytical variation. Inter-individual variation was greater than intra-individual variability for most tests of CMI for both age groups. Furthermore, all CMI tests exhibited large day-to-day intra-individual variation (CV approximately 15% or greater) which was primarily due to biological rather than analytical sources, for both age groups. In conclusion, both age groups showed large between-person and considerable within-person variation in CMI tests. Therefore, assessment of CMI based on a single blood draw may not provide a reliable estimate of immune function.

Adult↗

PubMed2003

The skeleton as a unique environment for breast cancer cells.

Bone is a favored location for several cancer metastases especially breast, prostate and myeloma. This review evaluates various properties of the skeleton that contribute to its successful colonization by breast cancer cells. The first consideration is the unique aspects of the vasculature of metaphyseal bone, which may account for the initial lodging of breast cancer cells in specific regions of the skeleton. Metasphyseal bone, found at the ends of long bone, in ribs and in vertebrae, is comprised of trabecular bone interspersed with marrow and a rich vasculature. The chemotactic factors that arise from bone marrow and bone cells are discussed in terms of cancer cell migration out of the vasculature and entry of cancer cells into the marrow cavity. Once the breast cancer cells have migrated into the metaphysis, they interact both directly and indirectly with bone cells and other cells in the marrow. As tumor growth progresses, functional bone cells are lost, most likely through apoptosis.

Animals↗

PubMed2002

Exercise increases prolactin-receptor expression on human lymphocytes.

Plasma prolactin has been shown to increase during stress; the immune system is responsive to prolactin and affected by stress. Therefore, this study was undertaken to investigate the effects of acute graded, maximal treadmill exercise on prolactin-receptor expression by lymphocytes. Eight healthy men underwent one exercise and one nonexercise session. Blood was sampled immediately before and after the exercise. On the day of the nonexercise session, two resting blood samples were obtained at the same times as the exercise session samples to act as baseline data. Plasma prolactin concentrations were significantly elevated in response to exercise and correlated positively with total prolactin-receptor expression per B lymphocyte. An increase in total prolactin-receptor expression per B lymphocyte in response to exercise also was observed. In addition, exercise significantly increased the total number of circulating B lymphocytes expressing prolactin receptor as well as the total number of circulating B lymphocytes. These data support the idea that exercise may enhance the interaction between immune target cells and prolactin, a stress hormone capable of enhancing immune function.

Adult↗

PubMed2002

Effects of resistance training on resting immune parameters in women.

The aim of this investigation was to determine whether intense resistance training of 6 months duration influenced resting immune parameters. Previously untrained women underwent one of four training programs or were non-training controls (CON, n=7). The resistance-training groups trained for total body power (TP, n=16), total body hypertrophy (TH, n=18), upper body power (UP, n=15) or upper body hypertrophy (UH, n=15). Immune parameters were measured from a fasting morning blood draw in September/October (0 months, t(0)), November/December (3 months, t(3)), and April/May (6 months, t(6)). Lymphocyte subsets [CD4+ T cells, CD8+ T cells, natural killer cells (NK), and B cells], and mitogen-stimulated proliferation were measured. The concentration of NK cells increased ( P<0.001) after 3 months of training for the resistance-training groups but not the CON group. This increase was not present after 6 months of training, thus it was a transient change. Lymphocyte proliferation responses were similar across time for the resistance-trained and CON groups for all stimulation conditions. Thus, resistance training induces a transient increase in NK cells but has little effect on lymphocyte trafficking or proliferation. This was consistent despite differences in the volume of muscle mass trained or the manner of training (power verses hypertrophy).

Adolescent↗

PubMed2002

The effect of donor age on the sensitivity of osteoblasts to the proliferative effects of TGF(beta) and 1,25(OH(2)) vitamin D(3).

The loss of osteoblast function in aging bone is one of the major causes of osteopenia, or loss of bone mass. In this study, this loss of function was investigated by examining the proliferative response of rat long bone periosteal osteoblasts to TGF(beta1) and 1,25-dihydroxy vitamin D(3) (1,25-D(3)) as a function of donor age. Using a DNA binding fluorescent dye, DNA levels were measured in osteoblast cultures derived from either young adult (3-4 months) or old (14-15 months) rats following treatment with two concentrations (10(-9) M or 10(-12) M) of either 1,25-D(3) or TGF(beta1) or with vehicle. Cells from young rat bone, when treated with 1, 25-D(3), showed a dose-dependent increase in proliferation when treated with the higher dose and a decrease in proliferation when treated with the lower dose. Osteoblasts isolated from old rats did not respond to 1, 25-D(3) treatment. A similar pattern of response to TGF(beta1) was found. When treated with 10(-9) M TGF(beta1), the rate of proliferation increased for young rat osteoblasts, but the old rat derived cells were unresponsive. The 10(-12) M dose of TGF(beta1) was ineffective for both young and old cells. This study has shown that osteoblasts derived from old donors are impaired in their ability to respond to vitamin D and TGF(beta), two of the major controlling factors of skeletal development and maintenance.

Age Factors↗

PubMed2002

Maternal selenium nutrition and neonatal immune system development.

We evaluated the impact of dietary selenium intake on neonatal immune cell differentiation and function. A low selenium intake during pregnancy and lactation produced reductions in maternal plasma selenium (33%, p = 0.0001), milk selenium (36%, p = 0.001), and corresponding neonatal plasma selenium (47%, p = 0.008). Thymocytes from neonates receiving low-selenium milk showed an impaired activation in vitro (p = 0.001). The percentages of CD8 cytotoxic T cells (p = 0.03), CD2 T cells (p = 0.09), panB cells ( = 0.02), and natural killer cells (p = 0.07) were all decreased in neonates nursed by mothers fed a low-selenium diet. The results indicate that maternal selenium intake impacts neonatal selenium status which in turn influences the neonatal immune system development.

Animals↗