Gastrocnemius Mass Is Lower 28 Days After Recovery From A Cycle Of Cisplatin In Mice

Platinum-based chemotherapeutic agents, such as cisplatin, are widely employed as a primary treatment modality for various cancer types. Despite their efficacy, cisplatin\u27s mechanism of action involves inducing DNA damage in cells, leading to pronounced acute and long-term side effects. One well established side effect is rapid loss in muscle mass. However, very little is known about the long-term effects of chemotherapy treatment on muscle size. PURPOSE: of this study was to analyze the long-term effects of cisplatin on muscle mass recovery. We hypothesized that cisplatin would have a negative long-term effect on muscle recovery. METHODS: 5-6 month-old CD2F1 mice were divided into two groups receiving injections of either Cisplatin (Cis) or Vehicle (Veh); n = 10 per group. A clinically relevant chemotherapy cycle was completed by a once weekly injection of 5mg/kg body weight of cisplatin for four weeks. Veh mice received an equal volume of saline. Following the cycle, mice recovered in their cage for 28 days and then hindlimb muscles were taken. Data were analyzed using independent t-test and presented as mean ± standard error. RESULTS: The gastrocnemius mass was significantly lower (p=0.008) in cisplatin-treated mice (139.20 ± 4.98) compared to the vehicle-treated group (147.50 ± 2.26). Conversely, the soleus did not show a significant difference (p=0.756) between Cis (9.90 ± 0.46) and Veh (10.10 ± 0.44) groups. Similarly, the Plantaris did not demonstrate a significant difference (p=0.950) in Cis treatment (18.65 ± 0.57) compared to Veh (18.65 ± 0.54). CONCLUSION: These data indicate a diminished ability of the gastrocnemius, the primary hindlimb flexor, to recover after a bout of cisplatin drug treatment. Further research is needed to better understand the mechanisms behind muscle specific differences and failed muscle mass recovery in the gastrocnemius

Mitochondrial Dysfunction is Evident in Lewis Lung Carcinoma-Induced Muscle Wasting

Cancer cachexia is a paraneoplastic syndrome associated with adverse prognosis and shortened survival. The defining feature of cachexia is extensive muscle atrophy leading to progressive functional impairments. The molecular mechanisms responsible for the rapid muscle wasting are not fully elucidated. Based on emerging evidence, we developed the hypothesis cachectic muscle wasting is caused by mitochondrial dysfunction increasing reactive oxygen species production leading to global oxidative stress. To test this hypothesis we utilized the well-established Lewis-Lung Carcinoma (LLC) model of cancer cachexia. The time-course study consisted of one, two, three and four week LLC tumor bearing mice and age-matched four week saline (PBS) control (Ctrl) mice. Tumors were implanted into the hind flank at 1X106 cells in 100 µL PBS. The plantaris was weighed for wet mass then teased into small fiber bundles and permeabilized for the quantification of mitochondrial function. Mitochondrial dysfunction was classified by a decrease in the respiratory control ratio (RCR), which is the ratio of state 3 (maximal ADP stimulated respiration) to state 4 (oligomycin-induced leak respiration). Muscle mass progressively declined over the time-course, reaching significance at 4 weeks (Ctrl vs 4-week, p\u3c0.05). Mitochondrial function was not different among groups, however individual a priori comparison between groups revealed that 4wk cancer animals exhibited marked mitochondrial dysfunction compared to all other groups (p\u3c0.05). These data demonstrate that late stage cancer-induced muscle wasting is associated with significant mitochondrial dysfunction

Mitochondrial Dysfunction in Diaphragm Muscle Precedes the Cachectic Phenotype in LLC Tumor-Bearing Mice.

The defining feature of cancer cachexia is extensive weight loss and skeletal muscle atrophy. It is clinically important because cachexia reduces patient survival, results in functional impairment, and is estimated to be directly responsible for 20-40% of cancer deaths. Unfortunately, no clinical therapy exists and therefore, it is important to understand the molecular mechanisms responsible for rapid muscle wasting. Compared to limb muscles, the diaphragm is relatively understudied in cancer cachexia, but is likely to be adversely affected because cachexia is a systemic disease. Wasting of the primary inspiratory muscle may result in difficulty breathing and inability to adjust minute ventilation in response to a respiratory challenge. Based on emerging evidence, it is clear that oxidative stress is present in cachexia-induced wasting of the diaphragm; PURPOSE: we developed the hypothesis that mitochondrial dysfunction in the diaphragm precedes cachexia. METHODS: 1X106 Lewis Lung Carcinoma cells (LLC) or Phosphate-Buffered Saline (PBS, control) were implanted to the hind-flank of C57BL6/J mice at 8 wks of age. Tumors were allowed to develop for 1, 2, 3, or 4 wks. At designated time points diaphragms were collected and mitochondrial function was assessed by respiration and ROS production. RESULTS: Cancer cachexia was evident only at the 4 wk time point demonstrated by decrease in body mass and muscle atrophy in several limb muscles. Mitochondrial respiration, assessed by respiratory control ratio (state3/state 4 respiration), was significantly lower at 1 wk (pCONCLUSIONS:The molecular events that lead to muscle atrophy in cancer cachexia are unknown. We demonstrate that two hallmarks of mitochondrial dysfunction, altered respiration and ROS production, occur in the diaphragm well before the cancer cachexia phenotype is evident in the LLC model. These data suggest that the mitochondria are likely a suitable target to treat or prevent cancer cachexia-induced muscle wasting in the diaphragm

Fractional Synthetic Rate and Markers of Protein Turnover are Altered in the Diaphragms of Cachectic Mice

Cancer cachexia, a wasting syndrome characterized by rapid skeletal muscle wasting and fat loss, directly accounts for up to 20-40% of cancer-related deaths. All muscles, including respiratory muscles, are susceptible to atrophy because cancer cachexia is a systemic disease. Atrophy of the primary breathing muscle, the diaphragm, can lead to respiratory distress, which is commonly associated with a cachectic phenotype. Indeed, the diaphragm is more susceptible to atrophy in certain conditions, but little is known about the effects of cancer-cachexia on protein turnover in the diaphragm. Therefore, investigations into the alterations in protein turnover could provide insight to the molecular events and provide valuable information in the search for therapeutic targets. PURPOSE: The purpose of this study was to describe changes in diaphragmatic protein synthesis and molecular markers of synthesis and degradation during the progression of cancer cachexia. METHODS: C57BL6/J mice (8 wks old) were implanted with 1X106 Lewis Lung Carcinoma cells (LLC) or Phosphate-Buffered Saline (PBS, control). Tumors developed over a 1-4 wk time course and diaphragms were harvested at each time point (1, 2, 3, or 4 wks). Fractional synthetic rates (FSR) were determined using deuterium incorporation into muscle. Selected markers of protein synthesis and degradation pathways were analyzed by immunoblot analysis. One-Way ANOVA was used for statistical analyses, with significance set at pRESULTS: FSR trended downward over time, but did not reach significance. Similar to FSR, anabolic signaling markers (4EBP-1, ERK1/2, Deptor) did not demonstrate significant differences. p62, an autophagic degradation marker, was significantly less than PBS in 3 wk diaphragms (

Disuse Atrophy Occurs Without a Change in Mitochondrial Respiratory Control Ratio During Hindlimb Unloading in Mice

Skeletal muscle atrophy commonly occurs during prolonged periods of inactivity, however, the precise mechanisms that cause muscle atrophy have yet to be determined. Specifically, a controversy exists on whether mitochondrial dysfunction is a cause or consequence of disuse muscle atrophy. PURPOSE: The purpose of this study was to determine if a change in the respiratory control ratio, which is a ratio of maximal O2 respiration to leak respiration, could be detected prior to muscle atrophy in a time-course study in mice. METHODS: Disuse atrophy was induced using hindlimb unloading (HU) in adult, C57BL/6J male mice for 0 (control), 1, 2, 3, or 7 days (n=~6-8/group). Following completion, gastrocnemius and soleus muscles were weighed and assessed for mitochondrial function in permeabilized muscle fibers. Here, we define mitochondrial function as the respiratory control ratio (RCR) determined by maximal ADP stimulated respiration (State 3) divided by leak or ATP synthase inhibited (state 4) respiration. A one-way ANOVA was used to determine differences between means. When significant F ratios were found, a Tukey post-hoc was used to compare differences between means. Values presented are mean ± standard error RESULTS: In both the gastrocnemius and soleus, muscle mass was not significantly different from control at day 1, but was significantly lower at 2, 3, and 7-day timepoints. In contrast, there was no significant difference in RCR in gastrocnemius (control 3.11±0.20, 1 day 2.96±0.60, 2 day 3.07±0.31, 3 day 3.08±0.25, 7 day 3.41± .29) or soleus (control 2.33±0.33, 1 day 2.77±0.33, 2 day 3.03±0.51, 3 day 2.93±0.30, 7 day 2.78±0.48). CONCLUSION: It is well established that HU causes rapid muscle atrophy. These data support mitochondrial RCR does decrease before muscle atrophy in either gastrocnemius or soleus muscle, and therefore may not be a primary cause of HU-induced muscle atrophy in mice

Partial or Complete Unloading of Skeletal Muscle Leads to Specific Alterations of Anabolic Signal Transduction

Consequences of disuse atrophy of skeletal muscle observed during spaceflight on astronaut health and performance are a focal point of space research. Decrements of both muscle mass and protein synthesis rates have been observed with exposure to varying muscle loading environments (1G \u3e partial loading \u3e 0G), and most of the reduced muscle mass can be attributed to diminished rates of synthesis. However, specific mechanisms behind unloading-dependent reductions of protein synthesis are not well defined. PURPOSE: To determine whether or not alterations of anabolic signal transduction was responsible for the changes previously observed in fractional synthesis rates with specific gravitational loading paradigms. METHODS: Female BALB/cByJ were normalized by bodyweight and assigned to normal cage ambulation (1G), partial weight bearing suspension titrated to approximately 33% bodyweight (G/3), partial weight bearing titrated to 16% bodyweight (G/6) and full unloading of hind limbs (0G) in specially designed cages. All mice were subjected to that loading environment for 21d prior to tissue harvest, and monitored daily. Immunoblotting of the gastrocnemius (n=23) was carried out to analyze alterations of anabolic signal transduction. Although numerous signaling intermediates were assessed, the focus of this abstract will be on ribosomal protein S6 kinase (p70-S6K). This important protein has served as a marker of protein synthesis signal transduction as well as the anabolic capacity in skeletal muscle. RESULTS: Regardless of loading paradigm, no differences were detected among groups for the activation of p70-S6K (as indicated by the phospho: total protein content). Total protein content, however, was ~27% lower than control in 0G and G/3 (P=0.008) with G/6 not being different from control (P\u3e0.05). CONCLUSION: In combination with previous data (unpublished observations), Partial gravitational fields at least partially rescues anabolic signaling, suggesting that a threshold level of stimulus is necessary to maintain anabolic capacity in muscle. These results may have important implications towards the development of strategies designed to counter the effects of partial/complete unloading on skeletal muscle based on how the anabolic capacity of muscle is affected

Males, but Not Females, Demonstrate Mitochondrial Dysfunction in the C26 Model of Cancer Cachexia

Cancer cachexia is characterized by progressive muscle wasting that can lead to symptoms such as anemia, severe weight loss, and fatigue. These symptoms can lead to limitations in activities of daily living and can cause resistance to chemotherapy treatments in cancer patients. There are no current treatments available to treat cancer cachexia and a critical need remains to identify mechanisms of cancer cachexia. Recently, our group identified mitochondrial disfunction precedes muscle atrophy in males but not females in a model of lung cancer induced atrophy. However, it is unknown whether this finding is replicated when studying a different type of cancer. PURPOSE: This study set out to determine if mitochondrial respiration is impaired in the plantaris muscle in a well-established colon cancer model of cachexia. METHODS: The time-course study consisted of male and female mice in four groups per sex: An age-matched control (PBS), and three groups implanted with C26 tumors. Tumor growth for 10-15 days, 20 days, and 25 days. Tumors were implanted bilaterally into the hind flank for a total of 1X106 cells PBS (one-half per each hindflank). The plantaris was weighed for wet mass then teased into small fiber bundles and permeabilized for the quantification of mitochondrial function. Mitochondrial dysfunction was classified by a decrease in the respiratory control ratio (RCR), which is the ratio of state 3 (maximal ADP stimulated respiration) to state 4 (oligomycin-induced leak respiration). Male and Female data were analyzed separately using a one-way ANOVA. RESULTS: The tumor burden increased as the number of days increased. Male RCR showed a mean difference in RCR at the early timepoint (10-15 day, p=0.058) and demonstrated significantly lower RCR at the 20 day timepoint compared to PBS control (20d= 1.170± 0.094, PBS= 2.41 ± 0.13, p=0.031). Interestingly, RCR was not significantly different between male PBS and 25 days (1.864± 0.21, p=0.084). RCR in the plantaris from females was not different among any of the groups (p=0.401). CONCLUSION: Along with our previously published data in a lung cancer model, these data indicate that the mechanisms of muscle atrophy are sex dependent. Specifically, mitochondrial dysfunction appears to play an important role in cancer-induced atrophy in male, but not female, mice

WFPC2 Observations of the Hubble Deep Field-South

The Hubble Deep Field-South observations targeted a high-galactic-latitude field near QSO J2233-606. We present WFPC2 observations of the field in four wide bandpasses centered at roughly 300, 450, 606, and 814 nm. Observations, data reduction procedures, and noise properties of the final images are discussed in detail. A catalog of sources is presented, and the number counts and color distributions of the galaxies are compared to a new catalog of the HDF-N that has been constructed in an identical manner. The two fields are qualitatively similar, with the galaxy number counts for the two fields agreeing to within 20%. The HDF-S has more candidate Lyman-break galaxies at z > 2 than the HDF-N. The star-formation rate per unit volume computed from the HDF-S, based on the UV luminosity of high-redshift candidates, is a factor of 1.9 higher than from the HDF-N at z ~ 2.7, and a factor of 1.3 higher at z ~ 4.Comment: 93 pages, 25 figures; contains very long table

The Hubble Deep Field South Flanking Fields

As part of the Hubble Deep Field South program, a set of shorter 2-orbit observations were obtained of the area adjacent to the deep fields. The WFPC2 flanking fields cover a contiguous solid angle of 48 square arcminutes. Parallel observations with the STIS and NICMOS instruments produce a patchwork of additional fields with optical and near-infrared (1.6 micron) response. Deeper parallel exposures with WFPC2 and NICMOS were obtained when STIS observed the NICMOS deep field. These deeper fields are offset from the rest, and an extended low surface brightness object is visible in the deeper WFPC2 flanking field. In this data paper, which serves as an archival record of the project, we discuss the observations and data reduction, and present SExtractor source catalogs and number counts derived from the data. Number counts are broadly consistent with previous surveys from both ground and space. Among other things, these flanking field observations are useful for defining slit masks for spectroscopic follow-up over a wider area around the deep fields, for studying large-scale structure that extends beyond the deep fields, for future supernova searches, and for number counts and morphological studies, but their ultimate utility will be defined by the astronomical community.Comment: 46 pages, 15 figures. Images and full catalogs available via the HDF-S at http://www.stsci.edu/ftp/science/hdfsouth/hdfs.html at present. The paper is accepted for the February 2003 Astronomical Journal. Full versions of the catalogs will also be available on-line from AJ after publicatio

Mitochondrial function and protein turnover in the diaphragm are altered in llc tumor model of cancer cachexia

It is established that cancer cachexia causes limb muscle atrophy and is strongly associated with morbidity and mortality; less is known about how the development of cachexia impacts the diaphragm. The purpose of this study was to investigate cellular signaling mechanisms related to mitochondrial function, reactive oxygen species (ROS) production, and protein synthesis during the development of cancer cachexia. C57BL/J6 mice developed Lewis Lung Carcinoma for either 0 weeks (Control), 1 week, 2 weeks, 3 weeks, or 4 weeks. At designated time points, diaphragms were harvested and analyzed. Mitochondrial respiratory control ratio was ~50% lower in experimental groups, which was significant by 2 weeks of cancer development, with no difference in mitochondrial content markers COXIV or VDAC. Compared to the controls, ROS was 4-fold elevated in 2-week animals but then was not different at later time points. Only one antioxidant protein, GPX3, was altered by cancer development (~70% lower in experimental groups). Protein synthesis, measured by a fractional synthesis rate, appeared to become progressively lower with the cancer duration, but the mean difference was not significant. The development and progression of cancer cachexia induces marked alterations to mitochondrial function and ROS production in the diaphragm and may contribute to increased cachexia-associated morbidity and mortality