Delayed onset muscle soreness following repeated bouts of downhill running

Perceived muscle soreness ratings, serum creatine kinase (CK) activity, and myoglobin levels were assessed in three groups of subjects following two 30-min exercise bouts of downhill running (-10 degrees slope). The two bouts were separated by 3, 6, and 9 wk for groups 1, 2, and 3, respectively. Criterion measures were obtained pre- and 6, 18, and 42 h postexercise. On bout 1 the three groups reported maximal soreness at 42 h postexercise. Also, relative increases in CK for groups 1, 2, and 3 were 340, 272, and 286%, respectively. Corresponding values for myoglobin were 432, 749, and 407%. When the same exercise was repeated, significantly less soreness was reported and smaller increases in CK and myoglobin were found for groups 1 and 2. For example, the percent CK increases on bout 2 for groups 1 and 2 were 63 and 62, respectively. Group 3 demonstrated no significant difference in soreness ratings, CK activities, or myoglobin levels between bouts 1 and 2. It was concluded that performance of a single exercise bout had a prophylactic effect on the generation of muscle soreness and serum protein responses that lasts up to 6 wk.     

Aflatoxin biosynthetic pathway: Elucidation by using blocked mutants of Aspergillus parasiticus

Two mutant strains of Aspergillus parasiticus, both deficient in aflatoxin production, were used to elucidate the biosynthetic pathway of this mycotoxin. One of the mutants, A. parasiticus ATCC 24551, was capable of accumulating large amounts of averufin, and the other, A. parasiticus 1-11-105 wh-1, accumulated versicolorin A. The averufin producing mutant efficiently converted ¹⁴C-labeled versiconal acetate, versicolorin A, and sterigmatocystin into aflatoxin B₁ and G₁, indicating that averufin preceded these compounds in the aflatoxin biosynthetic pathway. In the presence of dichlorvos (dimethyl 2,2-dichlorovinyl phosphate), a known inhibitor of aflatoxin biosynthesis, the conversion of versicolorin A and sterigmatocystin was unaffected, but the conversion of versiconal acetate was markedly inhibited. The mutant accumulating versicolorin A incorporated ¹⁴C-labeled acetate, averufin, and versiconal acetate into versicolorin A. In the presence of dichlorvos, however, the major conversion product was versiconal acetate. This strongly suggested that dichlorvos inhibited the conversion step of versiconal acetate into versicolorin A. This mutant resumed production of aflatoxin B₁ if sterigmatocystin was added to the resting cell cultures, indicating that the mutant was blocked at the enzymatic step catalyzing the conversion of versicolorin A into sterigmatocystin, and as a result was incapable of aflatoxin production. The experimental evidence is thus provided for the involvement and interrelationship of three anthraquinones (averufin, versiconal acetate, and versicolorin A) and a xanthone (sterigmatocystin) in aflatoxin biosynthesis. A pathway for the biosynthesis of aflatoxin B₁ is proposed to be: acetate →→→ averufin → versiconal acetate → versicolorin A → sterigmatocystin → aflatoxin B₁.     

Enhancement in recall antigen responses by frequent,repetitive skin testing with candida,mumps, and streptokinase-streptodornase in 38 normal adults

Summary Candida, mumps, and streptokinase-streptodornase (SKSD) were administered intradermally to 38 healthy adult volunteers at weeks 0, 2, 4–5, and 14 during two separate trials. Frequent, repetitive testing was used to determine (1) whether responses remained stable; (2) the relationship of erythema to induration; and (3) whether results would change when analyzed by different methods of comparing endpoints.When Candida, mumps, and SKSD were first administered, 63%, 76%, and 88% of the subjects responded with 5 mm induration by 48 h. Although little sex difference was noted for mumps and SKSD responses, more men responded to Candida (P=0.001). Erythema and induration were linearly correlated for Candida and SKSD, but the results were variable for mumps. With frequent repetitive testing, the mean induration arising in response to Canadida increased (P=0.001), as did the number of responses >15 mm (P=0.05). Similarly, the mean mumps-induced induration increased (P=0.01), as did the number of responses >10 mm (P=0.05). The mean SKSD-induced induration increased (P=0.08) in the first trial. During the second trial an SKSD overdosage occurred, which produced SKSD-specific anergy lasting for 25 weeks but not affecting Canadida and mumps responses. All enhanced induration responses decreased toward baseline levels during a 10-week rest period. The graded-response method of data analysis was more sensitive than the positive-negative or mean induration methods for detecting significant induration enhancement. Appropriate controls are needed for meaningful data analysis during repetitive skin testing with these antigens.     

Enzymes of glycogen metabolism and related metabolites in preimplantation mouse embryos

Preimplantation mouse embryos were individually analyzed for glycogen phosphorylase, P-glucomutase, UDPG, UTP, ATP, and the sum of other nucleotide triphosphates (i.e., GTP + CTP). UDPG changes during starvation and refeeding were also determined. Phosphorylase activity was exceedingly low at the two-cell stage and rose eightfold by the morula stage. P-glucomutase was 2000 times more active than phosphorylase in two-cell embryos and fell progressively to about half the initial level by the eight-cell stage. UDPG was highest in one-cell embryos, fell to less then 20% by the two-cell stage, then recovered to about a 35% level at later stages. The ATP to UTP ratio varied from about 5:1 at the earliest stages to about 3:1 in eight-cell and older embryos. GTP plus CTP was 50% higher than UTP at the one-cell stage but was equal to UTP or lower thereafter. The results combined with earlier data from several laboratories indicate that (1) up to the morula stage the embryo can make glycogen but has difficulty using it because of insufficient glycogen phosphorylase and (2) UDPG and glucose-6-P levels are poorly coordinated, probably due to difficulty (or control) at the UDPG pyrophosphorylase step.     

Hypoxia-induced apoptosis in endothelial cells and embryonic stem cells

Background: To evaluate the influence of hypoxia and molecular events in endothelial and embryonic stem cells.Materials and Methods: Human umbilical vein endothelial cells (HUVECs) and mouse embryoid body (EB) cells were subjected to hypoxic conditions for different time courses. DNA fragmentation assay, quantification of apoptotic cells by TUNEL assay measured by flowcytometry, and Western blot analysis for the molecular events of apoptosis were performed.Results: DNA fragmentation could be identified under hypoxic conditions in HUVECs and mouse EBs. The DNA fragmentation increased when the hypoxic interval was extended.In situ internucleosomal DNA fragmentation-TUNEL assay also found that the percentages of apoptotic cells increased gradually in HUVECs and mouse EBs when the hypoxic interval was extended. Furthermore, the levels of expression of p53 and Bax both increased in hypoxic conditions.Conclusions: Hypoxia increases both HUVEC and mouse EB apoptosis, which is associated with increase in p53/Bax expression.     

A general tendency for conservation of protein length across eukaryotic kingdoms

Protein elongation can occur in many ways, such as domain duplication or insertion and as recruitment of a transposable element fragment into the coding region, and it is believed to be a general tendency in protein evolution. Indeed, a previous study showed that yeast proteins are, on average, longer than their orthologs in bacteria, and in this study, we found that proteins in yeast, nematode, Drosophila, human, and Arabidopsis are, on average, longer than their orthologs in Escherichia coli. Surprisingly, however, we found conservation of protein sequence length across eukaryotic kingdoms. We collected 1,252 orthologous proteins from yeast, nematode, Drosophila, human, and Arabidopsis and found that the total length of these proteins is very similar among the five species and that there is no general tendency for a protein to increase or decrease in length. Furthermore, although paralogous proteins tend to undergo more sequence-length changes, there is also no general tendency for length increase. However, proteins that are commonly shared by Drosophila and human but not by yeast are, on average, substantially longer than proteins that are shared by yeast, Drosophila, and human. This is a puzzle that begs for an answer.     

NMR spectroscopic, mass spectroscopic, X-ray crystallographic, and theoretical studies of molecular mechanics of natural products: farformolide B and sesamin

Two natural products, farformolide B and sesamin were isolated from Farfugium japonicum and Cinnamomum kanehirae, respectively. The structures of the two natural products, including their relative stereochemistry, were elucidated using spectroscopic data and theoretical calculations. The molecule 1 (farformolide B) is newly recognized by X-ray crystallography. The two compounds were also investigated by a theoretical analysis using the B3LYP/6-31G* method of the Gaussian 03 package program. The theoretical results were supplemented by experimental data to determine the optimal geometric structures of the two compounds. The calculated molecular mechanics were found to compare well with the experimental data. Several important thermodynamic properties of the two products, including ionization potentials, highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energies, energy gaps, heat of formation, atomization energies, and vibration frequencies, were also calculated. The study also provided a good understanding of the stereochemical structure and thermodynamic properties of the two molecules.     

Effects of caloric restriction on cell proliferation in several tissues in mice: role of intermittent feeding

Reduced cell proliferation may mediate anticarcinogenic effects of caloric restriction (CR). Using heavy water (2H2O) labeling, we investigated the cell proliferation response to CR in detail, including time course, effect of refeeding, and role of intermittent feeding with 5% CR. In the time-course study, 8-wk-old female C57BL/6J mice were placed on a 33% CR regimen (fed 3 times/wk) for varying durations. Compared with responses in controls fed ad libitum (AL), proliferation rates of keratinocytes, mammary epithelial cells, and T cells were markedly reduced within 2 wk of CR. In mice fed 95% ad libitum (C95, fed 3 times/wk), cell proliferation was also reduced in all tissues so that differences from 33% CR were only significant at 1 mo. In the refeeding study, mice were refed a C95 diet for varying durations after 1 mo of 33% CR. Cell proliferation rebounded to a suprabasal rate in all tissues after 2 wk of refeeding and then normalized after 2 mo, although the C95 group again exhibited lower cell proliferation than the AL group. The role of intermittent feeding was studied by comparing 33% CR and C95 animals (both fed intermittently) with animals fed isocalorically either daily or continuously by pellet dispenser. Intermittent feeding had no additive effect on 33% CR but reduced cell proliferation in all tissues at the 95% caloric intake level. In summary, the CR effect on cell proliferation is potent, rapid, and reversible in several tissues, and an intermittent feeding pattern reproduces much of the effect in the absence of substantial CR.     

COQ9, a new gene required for the biosynthesis of coenzyme Q in Saccharomyces cerevisiae

Currently, eight genes are known to be involved in coenzyme Q6 biosynthesis in Saccharomyces cerevisiae. Here, we report a new gene designated COQ9 that is also required for the biosynthesis of this lipoid quinone. The respiratory-deficient pet mutant C92 was found to be deficient in coenzyme Q and to have low mitochondrial NADH-cytochrome c reductase activity, which could be restored by addition of coenzyme Q2. The mutant was used to clone COQ9, corresponding to reading frame YLR201c on chromosome XII. The respiratory defect of C92 is complemented by COQ9 and suppressed by COQ8/ABC1. The latter gene has been shown to be required for coenzyme Q biosynthesis in yeast and bacteria. Suppression by COQ8/ABC1 of C92, but not other coq9 mutants tested, has been related to an increase in the mitochondrial concentration of several enzymes of the pathway. Coq9p may either catalyze a reaction in the coenzyme Q biosynthetic pathway or have a regulatory role similar to that proposed for Coq8p.