Chronic developmental hypoxia alters mitochondrial oxidative capacity and reactive oxygen species production in the fetal rat heart in a sex-dependent manner.

Insufficient oxygen supply (hypoxia) during fetal development leads to cardiac remodeling and a predisposition to cardiovascular disease in later life. Previous work has shown hypoxia causes oxidative stress in the fetal heart and alters the activity and expression of mitochondrial proteins in a sex-dependent manner. However, the functional effects of these modifications on mitochondrial respiration remain unknown. Furthermore, while maternal antioxidant treatments are emerging as a promising new strategy to protect the hypoxic fetus, whether these treatments convey similar protection to cardiac mitochondria in the male or female fetus has not been investigated. Therefore, using an established rat model, we measured the sex-dependent effects of gestational hypoxia and maternal melatonin treatment on fetal cardiac mitochondrial respiration, reactive oxygen species (ROS) production, and lipid peroxidation. Pregnant Wistar rats were subjected to normoxia or hypoxia (13% oxygen) during gestational days (GDs) 6-20 (term ~22 days) with or without melatonin treatment (5 µg/ml in maternal drinking water). On GD 20, mitochondrial aerobic respiration and H2 O2 production were measured in fetal heart tissue, together with lipid peroxidation and citrate synthase (CS) activity. Gestational hypoxia reduced maternal body weight gain (p < .01) and increased placental weight (p < .05) but had no effect on fetal weight or litter size. Cardiac mitochondria from male but not female fetuses of hypoxic pregnancy had reduced respiratory capacity at Complex II (CII) (p < .05), and an increase in H2 O2 production/O2 consumption (p < .05) without any changes in lipid peroxidation. CS activity was also unchanged in both sexes. Despite maternal melatonin treatment increasing maternal and fetal plasma melatonin concentration (p < .001), melatonin treatment had no effect on any of the mitochondrial parameters investigated. To conclude, we show that gestational hypoxia leads to ROS generation from the mitochondrial electron transport chain and affects fetal cardiac mitochondrial respiration in a sex-dependent manner. We also show that maternal melatonin treatment had no effect on these relationships, which has implications for the development of future therapies for hypoxic pregnancies.

Are Multiple Mitochondrial Related Signalling Pathways Involved in Carotid Body Oxygen Sensing?

It is generally acknowledged that the carotid body (CB) type I cell mitochondria are unique, being inhibited by relatively small falls in PaO2 well above those known to inhibit electron transport in other cell types. This feature is suggested to allow for the CB to function as an acute O2 sensor, being stimulated and activating systemic protective reflexes before the metabolism of other cells becomes compromised. What is less clear is precisely how a fall in mitochondrial activity links to type I cell depolarisation, a process that is required for initiation of the chemotransduction cascade and post-synaptic action potential generation. Multiple mitochondrial/metabolic signalling mechanisms have been proposed including local generation of mitochondrial reactive oxygen species (mitoROS), a change in mitochondrial/cellular redox status, a fall in MgATP and an increase in lactate. Although each mechanism is based on compelling experimental evidence, they are all not without question. The current review aims to explore the importance of each of these signalling pathways in mediating the overall CB response to hypoxia. We suggest that there is unlikely to be a single mechanism, but instead multiple mitochondrial related signalling pathways are recruited at different PaO2s during hypoxia. Furthermore, it still remains to be determined if mitochondrial signalling acts independently or in partnership with extra-mitochondrial O2-sensors.

Mitochondrial Succinate Metabolism and Reactive Oxygen Species Are Important but Not Essential for Eliciting Carotid Body and Ventilatory Responses to Hypoxia in the Rat.

Reflex increases in breathing in response to acute hypoxia are dependent on activation of the carotid body (CB)-A specialised peripheral chemoreceptor. Central to CB O2-sensing is their unique mitochondria but the link between mitochondrial inhibition and cellular stimulation is unresolved. The objective of this study was to evaluate if ex vivo intact CB nerve activity and in vivo whole body ventilatory responses to hypoxia were modified by alterations in succinate metabolism and mitochondrial ROS (mitoROS) generation in the rat. Application of diethyl succinate (DESucc) caused concentration-dependent increases in chemoafferent frequency measuring approximately 10-30% of that induced by severe hypoxia. Inhibition of mitochondrial succinate metabolism by dimethyl malonate (DMM) evoked basal excitation and attenuated the rise in chemoafferent activity in hypoxia. However, approximately 50% of the response to hypoxia was preserved. MitoTEMPO (MitoT) and 10-(6'-plastoquinonyl) decyltriphenylphosphonium (SKQ1) (mitochondrial antioxidants) decreased chemoafferent activity in hypoxia by approximately 20-50%. In awake animals, MitoT and SKQ1 attenuated the rise in respiratory frequency during hypoxia, and SKQ1 also significantly blunted the overall hypoxic ventilatory response (HVR) by approximately 20%. Thus, whilst the data support a role for succinate and mitoROS in CB and whole body O2-sensing in the rat, they are not the sole mediators. Treatment of the CB with mitochondrial selective antioxidants may offer a new approach for treating CB-related cardiovascular-respiratory disorders.

[Frequency of drug resistant tuberculosis in Poland in 2000 as compared to 1997]. / Czestosc wystepowania gruzlicy lekoopornej w Polsce w 2000 R. w porównaniu z 1997 r.

Prevalence of drug resistance to one drug and multidrug resistance--MDR in different categories of tuberculosis patients is an important information about the susceptibility pattern of Mycobacterium tuberculosis isolates against antimycobacterial drugs. Poland joined WHO/IUATLD global project on TB drug resistance surveillance, and carried out in 1996/1997 the first prospective survey, simultaneously on primary and acquired drug resistance. This study is repeated in 2000 according to the WHO/IUATLD protocol. The programme covered the whole country. A total of 16 regional centers participated in the co-operative study. 3705 questionnaires and cultures were obtained from patients who excreted TB bacilli during the 12-months from 1 st. January to 31st December 2000. Drug resistance tests to INH, RMP, SM, EMB were performed on Lowenstein-Jensen medium according to the proportion method or/and Bactec 460 TB system. 3705 TB patients (3037 new and 668 treated cases) bacteriologically confirmed by culture were included in one-year study. Primary resistance to any drug was found in 6.12% (CI 5.27-6.56) of new cases. 35 patients (1.15%, CI 0.77-1.35) were infected with MDR strains. Acquired resistance to any drug was found in 16.6% (CI 5.27-6.56), 8.53% (CL 6.41-9.6) of the patients who excreted MDR strains. We have found increased resistance from 3.6% in 1997 to 6.12% (p < 0.001) in 2000 and MDR from 0.6% in 1997 to 1.15% (p < 0.001) in 2000 in untreated tuberculosis patients in Poland. The rate of resistance in the group of treated TB patients was very similar in 1997 (17.0%) and in 2000 (16.6%); except 20% increase of MDR cases--(7.0% in 1997, and 8.53% in 2000). We observed an increase in drug resistant tuberculosis first time during 40 years long period of its monitoring. Regular monitoring of drug resistance in TB patients in Poland is recommended.

[Sensitivity of microscopy for detection of mycobacterium tuberculosis and MOTT (mycobacteria other than tuberculosis) on the basis of analysis 22.218 clinical materials submitted in 1998-2001 to the Department of Microbiology in National Tuberculosis and Lung Diseases Research Institute in Warsaw, Poland]. / Czulosc metody bakterioskopowej w wykrywaniu pratków gruzlicy i MOTT na podstawie analizy 22.218 badan diagnostycznych przeprowadzonych w Zakladzie Mikrobiologii IGiCHP w okresie 1998-2001.

The results of 22.218 respiratory specimens sent to our laboratory were studied to determine the sensitivity of the Ziehl-Neelsen (Z-N) stain and microscopy-fluorescence method for detection of M.tbc and MOTT. There were no AIDS patients among analyzed cases. Smears were positive for acid fast bacilli (AFB) 60.0% (480 of 800) of specimens growing M. tuberculosis and 25.1% (219 of 872) of specimens growing the six common species of MOTT. Smear positivity by species was 28.1% (141 of 502) for M. kansasii, 29.4% (43 of 146) for MAIC, 28.7% (35 of 122) for M. xenopi. No smear was positive for M. gordone (43 cultures), M. fortuitum (33 cultures), M. scrofulaceum (26 cultures). The rate of nonculturable mycobacteria on L-J medium was 0.2%; mean rate of contamination was 4.6%. We also analyzed the relation between the number of AFB seen on the smear and time of the growth of M. tuberculosis and relation between abundance of the culture growth and AFB seen on smears. These study suggest that the sensitivity of microscopy for Mycobacterium tuberculosis is comparable with the data of others authors. Sensitivity of microscopy is lower in MOTT detection than for M.tbc (p < 0.001). Time of growth and abundance of the M. tuberculosis cultures were adequate to AFB seen in microscopy.