Serum and urinary markers of skeletal muscle tissue damage after weight lifting exercise

The purpose of this study was to determine whether high intensity weight lifting exercise produces elevations of urinary 3-methylhistidine (3-MH), serum creatine kinase activity (CK), and serum myoglobin concentration (MY), and whether trained weight lifters differed in such responses when compared to a group of untrained subjects. Ten experienced male weight lifters (EWL) and seven untrained male subjects (IWL) performed three sets of six weight lifting exercises at 70%-80% of 1 RM. All subjects consumed a meat-free diet. The 3-MH:creatinine (3-MH:CR) values decreased 24 h and 48 h following exercise (P less than 0.05). The 12-h and 24-h postexercise CK response and the 12-h postexercise MY response increased for both EWL and IWL (P less than 0.05). However, EWL had a lower 24-h postexercise CK response and lower 12-h and 24-h postexercise MY responses compared to IWL (P less than 0.05). Within 48 h following weight lifting exercise, skeletal muscle protein degradation (as assessed by 3-MH:CR values) decreased regardless of prior training experience whereas skeletal muscle tissue damage (as assessed by CK and MY responses) increased. However, prior weight lifting training appeared to diminish the extent of muscle tissue damage.     

Imaging thrombus with radiolabelled monoclonal antibody to platelets.

Indium-111-hydroxyquinoline labelled platelets, though useful in the detection of thrombus, have not gained widespread use owing to the time and technical skill required for their preparation. A study was therefore conducted evaluating a new method of imaging thrombus with platelets radiolabelled with a 111In labelled monoclonal antibody, P256, directed to the platelet surface glycoprotein complex IIb/IIIa. When the number of receptors occupied by P256 was less than 3% of the total available on the platelet surface platelet function, as assessed by platelet aggregometry, was undisturbed. P256 was radiolabelled with 111In using diethylenetriaminepenta-acetic acid, which achieved a specific activity of 185 MBq (5 mCi)/mg. No impairment of immunoreactivity was detected at this specific activity. Platelets were labelled with radiolabelled monoclonal antibody in vitro in two patients at a receptor occupancy of 6% and in vivo--that is, by direct intravenous injection of P256--in six patients at a receptor occupancy of 1%. In vivo recovery and biodistribution kinetics suggested that after in vitro labelling platelets were minimally activated. The 111In kinetics recorded after intravenous P256 suggested rapid and efficient radiolabelling of platelets and gave no indication of platelet activation. Of the six patients who received intravenous P256, three had documented thrombus, two of whom gave positive results on P256 platelet scintigraphy. The third subject had chronic deep venous thrombosis and was scintigraphically negative. Imaging thrombus using a radiolabelled monoclonal antibody directed to platelets appears to offer great potential as a simple, non-invasive approach to the diagnosis of thrombosis.     

Involvement of tyrosyl-tRNA synthetase in splicing of group I introns in Neurospora crassa mitochondria: biochemical and immunochemical analyses of splicing activity.

We reported previously that mitochondrial tyrosyl-tRNA synthetase, which is encoded by the nuclear gene cyt-18 in Neurospora crassa, functions in splicing several group I introns in N. crassa mitochondria (R. A. Akins and A. M. Lambowitz, Cell 50:331-345, 1987). Two mutants in the cyt-18 gene (cyt-18-1 and cyt-18-2) are defective in both mitochondrial protein synthesis and splicing, and an activity that splices the mitochondrial large rRNA intron copurifies with a component of mitochondrial tyrosyl-tRNA synthetase. Here, we used antibodies against different trpE-cyt-18 fusion proteins to identify the cyt-18 gene product as a basic protein having an apparent molecular mass of 67 kilodaltons (kDa). Both the cyt-18-1 and cyt-18-2 mutants contain relatively high amounts of inactive cyt-18 protein detected immunochemically. Biochemical experiments show that the 67-kDa cyt-18 protein copurifies with splicing and synthetase activity through a number of different column chromatographic procedures. Some fractions having splicing activity contain only one or two prominent polypeptide bands, and the cyt-18 protein is among the few, if not only, major bands in common between the different fractions that have splicing activity. Phosphocellulose columns resolve three different forms or complexes of the cyt-18 protein that have splicing or synthetase activity or both. Gel filtration experiments show that splicing activity has a relatively small molecular mass (peak at 150 kDa with activity trailing to lower molecular masses) and could correspond simply to dimers or monomers, or both, of the cyt-18 protein. Finally, antibodies against different segments of the cyt-18 protein inhibit splicing of the large rRNA intron in vitro. Our results indicate that both splicing and tyrosyl-tRNA synthetase activity are associated with the same 67-kDa protein encoded by the cyt-18 gene. This protein is a key constituent of splicing activity; it functions directly in splicing, and few, if any, additional components are required for splicing the large rRNA intron.     

Sphingolipid-binding proteins

Emerging information on sphingolipid metabolism and signaling is leading to a better understanding of cellular processes such as apoptosis, cancer, cell survival and aging. In this review, we discuss the involvement of sphingolipids in these processes and focus on underlying mechanisms based on sphingolipid:protein interactions. Due to the inherent difficulty of studying lipids, we discuss techniques that are useful in the elucidation of these interactions. We classify sphingolipid-binding proteins into four main classes: receptor, effector, enzyme, and transporter. Known structures of sphingolipid-binding proteins are surveyed, and sphingolipid-binding characteristics are described, acknowledging the limitations that there are presently insufficient protein:sphingolipid complexes for more definitive conclusions on this topic. Finally we summarize relevant literature to better inform the reader about sphingolipid:protein interactions.     

A TEST AND REVIEW OF THE ROLE OF EFFECTIVE POPULATION SIZE ON EXPERIMENTAL SEXUAL SELECTION PATTERNS

Experimental evolution, particularly experimental sexual selection in which sexual selection strength is manipulated by altering the mating system, is an increasingly popular method for testing evolutionary theory. Concerns have arisen regarding genetic diversity variation across experimental treatments: differences in the number and sex ratio of breeders (effective population size; N_e ) and the potential for genetic hitchhiking, both of which may cause different levels of genetic variation between treatments. Such differences may affect the selection response and confound interpretation of results. Here we use both census-based estimators and molecular marker-based estimates to empirically test how experimental evolution of sexual selection in Drosophila pseudoobscura impacts N_e and autosomal genetic diversity. We also consider effects of treatment on X-linked N_e s, which have previously been ignored. Molecular autosomal marker-based estimators indicate that neither N_e nor genetic diversity differs between treatments experiencing different sexual selection intensities; thus observed evolutionary responses reflect selection rather than any confounding effects of experimental design. Given the increasing number of studies on experimental sexual selection, we also review the census N_e s of other experimental systems, calculate X-linked N_e , and compare how different studies have dealt with the issues of inbreeding, genetic drift, and genetic hitchhiking to help inform future designs.     

Ovarian follicular activity and hormonal profile during estrous cycle in cows: the development of 2 versus 3 waves

Most estrous cycles in cows consist of 2 or 3 waves of follicular activity. Waves of ovarian follicular development comprise the growth of dominant follicles some of which become ovulatory and the others are anovulatory. Ovarian follicular activity in cows during estrous cycle was studied with a special reference to follicular waves and the circulating concentrations of estradiol and progesterone. Transrectal ultrasound examination was carried out during 14 interovulatory intervals in 7 cows. Ovarian follicular activity was recorded together with assessment of serum estradiol and progesterone concentrations. Three-wave versus two-wave interovulatory intervals was observed in 71.4% of cows. The 3-wave interovulatory intervals differed from 2-wave intervals in: 1) earlier emergence of the dominant follicles, 2) longer in length, and 3) shorter interval from emergence to ovulation. There was a progressive increase in follicular size and estradiol production during growth phase of each wave. A drop in estradiol concentration was observed during the static phase of dominant anovulatory follicles. The size of the ovulatory follicle was always greater and produced higher estradiol compared with the anovulatory follicle. In conclusion, there was a predominance of 3-wave follicular activity that was associated with an increase in length of interovulatory intervals. A dominant anovulatory follicle during its static phase may initiate the emergence of a subsequent wave. Follicular size and estradiol concentration may have an important role in controlling follicular development and in determining whether an estrous cycle will have 2 or 3-waves.