The Robinson Protocol: a treadmill anaerobic performance test

The current investigation was designed to further examine the reliability of the Robinson protocol, which is a run-to-exhaustion treadmill test. Robinson (10) originally examined this protocol with 5 subjects. The significance of the initial exploratory study was the impetus for expanding the study to examine the reliability of the protocol with a larger sample. Fifteen male subjects participated in 3 trial runs on the treadmill. The first trial was a modified McConnell (7) test to determine the aerobic capacity of each subject. The second and third trials were identical Robinson protocols (10). The first trial run mean, in seconds (262.04 +/- 74.50), was not significantly different from the second trial run mean (257.30 +/- 72.65), p = 0.526 (2 tailed). As expected, trial 1 and trial 2 were highly correlated (intraclass) (r = 0.927, p < 0.001). These results provide additional support for the hypothesis that the Robinson protocol with a greater subject pool is a reliable protocol that can be used in research studies interested in examining various physiological interventions or anaerobic training.     

The two SAMP repeats and their phosphorylation state in Drosophila Adenomatous polyposis coli-2 play mechanistically distinct roles in negatively regulating Wnt signaling

The tumor suppressor Adenomatous polyposis coli (APC) plays a key role in regulating the canonical Wnt signaling pathway as an essential component of the β-catenin destruction complex. C-terminal truncations of APC are strongly implicated in both sporadic and familial forms of colorectal cancer. However, many questions remain as to how these mutations interfere with APC’s tumor suppressor activity. One set of motifs frequently lost in these cancer-associated truncations is the SAMP repeats that mediate interactions between APC and Axin. APC proteins in both vertebrates and Drosophila contain multiple SAMP repeats that lack high sequence conservation outside of the Axin-binding motif. In this study, we tested the functional redundancy between different SAMPs and how these domains are regulated, using Drosophila APC2 and its two SAMP repeats as our model. Consistent with sequence conservation–based predictions, we show that SAMP2 has stronger binding activity to Axin in vitro, but SAMP1 also plays an essential role in the Wnt destruction complex in vivo. In addition, we demonstrate that the phosphorylation of SAMP repeats is a potential mechanism to regulate their activity. Overall our findings support a model in which each SAMP repeat plays a mechanistically distinct role but they cooperate for maximal destruction complex function.     

Biosynthesis of prostaglandins and thromboxane B2 by fetal lung homogenates

The conversion of arachidonic acid to prostaglandins (PG's) and thromboxane B₂ (TXB₂) was investigated in homogenates from fetal and adult bovine and rabbit lungs. Adult bovine lungs were very active in converting arachidonic acid (100 μg/g tissue) to both PGE₂ (10.7 μg/g tissue) and TXB₂ (6.2 μ/g tissue). Smaller amounts of PGF_2α (0.9 μ/g) and 6-oxoPGF_1α were formed. Homogenates from fetal calf lungs during the third trimester of pregnancy were quite active in converting arachidonic acid to PGE₂, but formed very little TXB₂, PGF_2α or 6-oxoPGF_1α. Homogenates from rabbit lungs converted arachidonic acid (100 μg/g) mainly to PGE₂, both before and after birth. The amount of PGE₂ formed increased during gestation to a maximum of about 6 μg/g tissue at 28 days of gestation. It then decreased to a minimum (1.5 μg/g) which was observed 8 days after birth, followed by an increase to about 4 μg/g in older rabbits.     

The chronic lymphatic leukemia lymphocyte: Correlation of functional,metabolic, and surface immunoglobulin characteristics

This study determined the correlation between the functional capacity of chronic lymphatic leukemia lymphocytes as determined by their response to nonspecific mitogens with their glucose metabolism and surface immunoglobulin characteristics. A majority of patients (12) were found to have lymphocytes with impaired transformation to both PHA and pokeweed mitogens. These cells also had impaired glucose metabolism in unstimulated cultures and failed to have the striking increase in glucose metabolism in response to mitogens which is characteristic of normal lymphocytes. Most of these lymphocytes had IgM surface immunoglobulins. However, we were not able to demonstrate surface immunoglobulins on the lymphocytes of one patient in this group. Two patients were found to have lymphocytes with normal lymphoblastic transformation to PHA and impaired transformation to pokeweed suggesting cells of T origin. The glucose metabolism of these lymphocytes were less impaired in unstimulated cultures than those of the other patients and had a striking increment in glucose metabolism in response to PHA similar to normal lymphocytes. Unexpectedly, these lymphocytes were found to have IgG on their surface suggesting cells of B origin. These results indicate that there may be two groups of CLL patients with clinically similar disease in whom the functional and metabolic characteristics of the lymphocytes are distinct and that the surface immunoglobulin characteristic of lymphocytes may not always predict their functional characteristic.     

Surfactant protein D reduces alveolar macrophage apoptosis in vivo

Surfactant protein D (SP-D) is a molecule of the innate immune system that recognizes the patterns of surface carbohydrate on pathogens and targets them for phagocytosis and killing. SP-D-deficient mice show an increased number of macrophages in the alveolar space, excess surfactant phospholipid, overproduction of reactive oxygen species, and the development of emphysema. We report here that SP-D-deficient mice have a 5- to 10-fold increase in the number of apoptotic and necrotic alveolar macrophages, as defined by annexin V and propidium iodine staining, respectively. Intrapulmonary administration of a truncated 60-kDa fragment of human recombinant SP-D reduces the number of apoptotic and necrotic alveolar macrophages and partially corrects the lipid accumulation in SP-D-deficient mice. The same SP-D fragment binds preferentially to apoptotic and necrotic alveolar macrophages in vitro, suggesting that SP-D contributes to immune homeostasis in the lung by recognizing and promoting removal of necrotic and apoptotic cells.