ACE inhibition modifies exercise-induced pro-angiogenic and mitochondrial gene transcript expression.

Skeletal muscle responds to endurance exercise with an improvement of biochemical pathways that support substrate supply and oxygen-dependent metabolism. This is reflected by enhanced expression of associated factors after exercise and is specifically modulated by tissue perfusion and oxygenation. We hypothesized that transcript expression of pro-angiogenic factors (VEGF, tenascin-C, Angpt1, Angpt1R) and oxygen metabolism (COX4I1, COX4I2, HIF-1α) in human muscle after an endurance stimulus depends on vasoconstriction, and would be modulated through angiotensin-converting enzyme inhibition by intake of lisinopril. Fourteen non-specifically trained, male Caucasians subjects, carried out a single bout of standardized one-legged bicycle exercise. Seven of the participants consumed lisinopril in the 3 days before exercise. Biopsies were collected pre- and 3 h post-exercise from the m. vastus lateralis. COX4I1 (P = 0.03), COX4I2 (P = 0.04) mRNA and HIF-1α (P = 0.05) mRNA and protein levels (P = 0.01) showed an exercise-induced increase in the group not consuming the ACE inhibitor. Conversely, there was a specific exercise-induced increase in VEGF transcript (P = 0.04) and protein levels (P = 0.03) and a trend for increased tenascin-c transcript levels (P = 0.09) for subjects consuming lisinopril. The observations indicate that exercise-induced expression of transcripts involved in angiogenesis and mitochondrial energy metabolism are to some extent regulated via a hypoxia-related ACE-dependent mechanism.

Adjustments of muscle capillarity but not mitochondrial protein with skiing in the elderly.

Downhill skiing in the elderly increases maximal oxygen uptake (VO2max) and carbohydrate handling, and produces muscle hypertrophy. We hypothesized that adjustments of the cellular components of aerobic glucose combustion in knee extensor muscle, and cardiovascular adjustments, would increase in proportion to VO2max. Nineteen healthy elderly subjects (age 67.5 ± 2.9 years) who completed 28.5 days of guided downhill skiing over 3 months were assessed for anthropometric variables, cardiovascular parameters (heart rate, hematocrit), VO2max, and compared with controls (n = 20). Biopsies of vastus lateralis muscle were analyzed for capillary density and expression of respiratory chain markers (NDUFA9, SDHA, UQCRC1, ATP5A1) and the glucose transporter GLUT4. Statistical significance was assessed with a repeated analysis of variance and Fisher's post-hoc test at a P value of 5%. VO2max increased selectively with ski training (+7 ± 2%). Capillary density (+11 ± 5%) and capillary-to-fiber ratio (12 ± 5%), but not the concentration of metabolic proteins, in vastus lateralis were increased after skiing. Cardiovascular parameters did not change. Fold changes in VO2max and capillary-to-fiber ratio were correlated and were under genetic control by polymorphisms of the regulator of vascular tone, angiotensin converting enzyme. The observations indicate that increased VO2max after recreational downhill ski training is associated with improved capillarity in a mainly recruited muscle group.

An optimal periconception maternal folate status for embryonic size: the Rotterdam Predict study.

OBJECTIVE: To investigate the association between periconception maternal folate status and embryonic size. DESIGN: Prospective periconception cohort study. SETTING: Erasmus University Medical Centre, Rotterdam, the Netherlands. POPULATION: Seventy-seven singleton pregnancies recruited in 2009 and 2010. METHODS: We recruited women before 8 weeks of gestation and performed weekly three-dimensional ultrasound scans from enrolment up to 13 weeks of gestation. As a measure of embryonic growth, crown-rump length (CRL) measurements were performed using V-Scope software in the BARCO I-Space. Maternal blood was collected to determine first-trimester long-term red blood cell (RBC) folate status. Non-malformed live births were included in the analysis. We calculated quartiles of RBC folate, square root-transformed CRL data and performed multivariable linear mixed model analyses. MAIN OUTCOME MEASURES: Serial first-trimester CRL measurements. RESULTS: In total, 484 ultrasound scans were performed in 77 women, in 440 (90.7%) of which CRLs could be measured. RBC folate in the third quartile (1513-1812 nmol/l) was significantly associated with an increased CRL compared with the first two quartiles (814-1512 nmol/l) and the upper quartile (1813-2936 nmol/l; P(overall) = 0.03; adjusted for gestational age, smoking, body mass index and fetal sex). Compared with the third quartile, embryos in the upper quartile were 24.2% smaller at 6(+0) weeks [4.1 mm (95% confidence interval 3.5, 4.7) versus 5.4 mm (95% confidence interval 4.8, 6.1)] and 7.6% smaller at 12(+0) weeks [55.1 mm (95% confidence interval 52.9, 57.3) versus 59.6 mm (95% confidence interval 57.4, 62.0)] of gestation. CONCLUSIONS: This study suggests that a very high maternal periconception folate status is associated with reduced embryonic size. Whether these effects are beneficial or harmful requires further investigation.

Isolation and sequencing of a cDNA encoding the hypoxanthine-guanine phosphoribosyltransferase from Toxoplasma gondii.

A hypoxanthine-guanine phosphoribosyltransferase-encoding gene (HGPRT) from Toxoplasma gondii has been isolated and sequenced. The identity of the enzyme was determined by sequence comparison and complementation in a mutant Escherichia coli.

Identification and cloning of the Mycobacterium avium folA gene, required for dihydrofolate reductase activity.

Dihydrofolate reductase is an essential bacterial enzyme necessary for the maintenance of intracellular folate pools in a biochemically active reduced state. In this report, the Mycobacterium avium folA gene was identified by functional genetic complementation, sequenced, and expressed for the first time. It has an open reading frame of 543 bp with a G + C content of 73%. The translated polypeptide sequence shows 58% identity to the consensus sequence of the conserved regions from eight other bacterial dihydrofolate reductases. Recombinant M. avium dihydrofolate reductase was expressed actively in Escherichia coli, and SDS-PAGE analysis revealed a 20 kDa species, agreeable with that predicted from the polypeptide sequence:

Monoclonal infection involving Mycobacterium avium presenting with three distinct colony morphotypes.

Recent reports indicate that polyclonal infections may play an important role in multiple drug resistance in Mycobacterium avium infections. We report here on the isolation of a single M. avium strain that appeared to have smooth colony morphology upon initial isolation on a Lowenstein-Jensen slant. Primary subculture onto Middlebrook 7H10, however, revealed three distinct morphotypes representing smooth opaque (SmO), smooth transparent (SmT), and rough (Rg) colony morphologies. All three morphotypes were identified as M. avium by standard biochemical procedures, Genprobe analysis, and mycolic acid patterns. Subsequent restriction fragment length polymorphism analysis, using SalI- and PvuII-digested genomic DNA, revealed identical patterns for hybridization with the IS1245 probe. Thin-layer chromatographic analysis of lipids from the three morphotypes revealed that only the SmT morphotype possessed what appeared to be lipid components similar to, but unlike, previously described serovar-specific glycopeptidolipid antigens. Further analysis of internally radiolabeled deacylated lipids from the SmT morphotype, by high-performance liquid chromatography and thin-layer chromatography, disclosed that some of these components can be internally radiolabeled with [14C] phenylalanine and [14C]mannose. These results suggest that these components are structurally similar to previously described glycopeptidolipid antigens. This is apparently the first report of a monoclonal infection involving a single strain of M. avium presenting with all three colony morphotypes, SmO, SmT, and Rg.

The two toxoplasma gondii hypoxanthine-guanine phosphoribosyltransferase isozymes form heterotetramers.

Two isozymes of the purine salvage enzyme hypoxanthine-guanine phosphoribosyltransferase (HGPRT) of the apicomplexan protozoan Toxoplasma gondii are encoded by the single HGPRT gene as a result of differential splicing. Western blotting of total T. gondii protein shows that both isozymes I and II, which differ by 49 amino acids, are expressed. Both form enzymatically active homotetramers when overexpressed in Escherichia coli. The specific activity of HGPRT-I is five times that of HGPRT-II. When both isozymes are co-expressed in E. coli, HGPRT-I.HGPRT-II heterotetramers form. The predominant heterotetramer has enzymatic activity similar to HGPRT-II, and gel filtration chromatography demonstrates that its size is intermediate between the sizes of HGPRT-I and HGPRT-II. Mass spectrometric analysis of cross-linked homo- and heterotetramers reveals species of distinct molecular mass for HGPRT-I, HGPRT-II, and HGPRT-I.HGPRT-II and suggests that the predominant heterotetramer consists of one HGPRT-I subunit and three HGPRT-II subunits. The implications of this finding are discussed.

Antimycobacterial activities of 2,4-diamino-5-deazapteridine derivatives and effects on mycobacterial dihydrofolate reductase.

Development of new antimycobacterial agents for Mycobacterium avium complex (MAC) infections is important particularly for persons coinfected with human immunodeficiency virus. The objectives of this study were to evaluate the in vitro activity of 2, 4-diamino-5-methyl-5-deazapteridines (DMDPs) against MAC and to assess their activities against MAC dihydrofolate reductase recombinant enzyme (rDHFR). Seventy-seven DMDP derivatives were evaluated initially for in vitro activity against one to three strains of MAC (NJ168, NJ211, and/or NJ3404). MICs were determined with 10-fold dilutions of drug and a colorimetric (Alamar Blue) microdilution broth assay. MAC rDHFR 50% inhibitory concentrations versus those of human rDHFR were also determined. Substitutions at position 5 of the pteridine moiety included -CH(3), -CH(2)CH(3), and -CH(2)OCH(3) groups. Additionally, different substituted and unsubstituted aryl groups were linked at position 6 through a two-atom bridge of either -CH(2)NH, -CH(2)N(CH(3)), -CH(2)CH(2), or -CH(2)S. All but 4 of the 77 derivatives were active against MAC NJ168 at concentrations of < or =13 microg/ml. Depending on the MAC strain used, 81 to 87% had MICs of < or =1.3 microg/ml. Twenty-one derivatives were >100-fold more active against MAC rDHFR than against human rDHFR. In general, selectivity was dependent on the composition of the two-atom bridge at position 6 and the attached aryl group with substitutions at the 2' and 5' positions on the phenyl ring. Using this assessment, a rational synthetic approach was implemented that resulted in a DMDP derivative that had significant intracellular activity against a MAC-infected Mono Mac 6 monocytic cell line. These results demonstrate that it is possible to synthesize pteridine derivatives that have selective activity against MAC.