Effect of supplemental oxygen on supramaximal exercise performance and recovery in cystic fibrosis

Shah, Ashish R., Thomas G. Keens, and David Gozal.Effect of supplemental oxygen on supramaximal exercise performance and recovery in cystic fibrosis. J. Appl.Physiol. 83(5): 1641-1647, 1997.The effects ofsupplemental O₂ on recovery fromsupramaximal exercise and subsequent performance remain unknown. Ifrecovery from exercise could be enhanced in individuals with chroniclung disease, subsequent supramaximal exercise performance could also be improved. Recovery from supramaximal exercise and subsequent supramaximal exercise performance were assessed after 10 min of breathing 100% O₂ or room air(RA) in 17 cystic fibrosis (CF) patients [25 ± 10 (SD) yrold, 53% men, forced expired volume in 1 s = 62 ± 21%predicted] and 17 normal subjects (25 ± 8 yr old, 59% men,forced expired volume in 1 s = 112 ± 15% predicted). Supramaximalperformance was assessed as the work of sustained bicycling at a loadof 130% of the maximum load achieved during a graded maximal exercise.Peak minute ventilation(E) andheart rate (HR) were lower in CF patients at the end of eachsupramaximal bout than in controls. In CF patients, single-exponentialtime decay constants indicated faster recovery of HR(_HR = 86 ± 8 and 73 ± 6 s in RA and O₂,respectively, P < 0.01). Similarly, fast and slow time constants of two-exponential equations providing thebest fit for ventilatory recovery were improved in CF patients duringO₂ breathing ( = 132.1 ± 10.5 vs. 82.5 ± 10.4 s; = 880.3 ± 300.1 vs. 368.6 ± 107.1 s,P < 0.01). However, no such improvements occurred in controls. Supramaximal performance after O₂ improved in CF patients (109 ± 6% of the 1st bout after O₂ vs. 94 ± 6% in RA, P < 0.01).O₂ supplementation had no effect on subsequent performance in controls (97 ± 3% inO₂ vs. 93 ± 3% in RA). Weconclude that supplemental O₂after a short bout of supramaximal exercise accelerates recovery andpreserves subsequent supramaximal performance in patients with CF.

     

Baclofen is cytoprotective to cerebral ischemia in gerbils

The release of the neurotransmitter, glutamate, and the activation of receptor operated calcium channels, may increase the degree of damage in ischemic brain tissue. Inhibition of excitatory neurotransmitters should therefore result in cytoprotection of ischemic brain tissue. In this study we evaluated the effect of baclofen, an inhibitor of presynaptic glutamate release, on ischemic gerbil cortex, hippocampus (CA 1 and CA4), striatum and thalamus. Histological evaluation was done in a blind manner in 4 groups (total 36 animals): a control group (9 animals) and three groups (27 animals) with varying doses of baclofen. For cerebral ischemia, we used single episode of five minutes of arterial occlusion of the carotid arteries. Baclofen in doses of 0, 25, 50, and 100 mg/kg were given to different groups five minutes prior to ischemic insult. This was followed by intraperitoneal injections given 24 and 48 hours after the initial insult. Statistically significant histological cytoprotection was demonstrated. Doses of 25 mg/kg appeared to demonstrate significant protection of the cortex (p=0.0002), the CA1 and CA4 regions of the hippocampus (p=0.0004 and 0.0001) respectively. At a dose of 50 mg/kg, significant cytoprotection was demonstrated at the hippocampus (CA1 and CA4 regions), in particular at the CA4 region (p=0.0029). The 100 mg/kg dose appeared to have most significant protection at the CA1 and CA4 regions of the hippocampus (both p=0.0001), striatum (p=0.0011), and the thalamus (p=0.0008). All statistical comparisons were done using non-parametric tests (Mann-Whitney U test). Our study demonstrates that baclofen is cytoprotective to ischemic neuronal cells, especially in the hippocampus. Clinically this may be beneficial to those patients with strokes or head injuries.     

A conceptual model for the assessment of depressional wetlands in the prairie pothole region

The U.S. Environmental Protection Agency's (EPA's), Environmental Monitoring and Assessment Program (EMAP) is developing a landscape-level conceptual model to evaluate the condition of depressional (basin-type) wetlands in the prairie pothole region (PPR) of the United States. This effort is underway to determine the current condition of the Nation's wetlands and to track how it is improving or degrading over time, as well as to identify management priorities over major geographic areas. The depressional wetlands in the PPR were selected by EMAP both because of the importance of this region for waterfowl and because of the efforts currently being conducted by federal agencies and academic institutions in this region. The PPR provides nesting habitat for more than 15 species of ducks, and supports as much as half of the total production of dabbling and diving ducks in North America. Wetlands in this area became a vulnerable resource after extensive draineage in the 1800s. We propose a conceptual model that represents a framework for guiding the development of ecological indicators, research activities, and data collection for the evaluation of wetland conditions. In princple, this conceptual model is applicable to wetlands in any part of the world.     

Conserved autonomy of replication of the X-chromosomes in hybrids of Drosophila miranda and Drosophila persimilis

The chromosome complement of hybrid males from the cross between Drosophila miranda female and D. persimilis male provides an interesting chromosomal situation where an autosome, the 3rd chromosome of D. persimilis, coexists with a homologue that developed into a sex chromosome, the X₂ in D. miranda. Except for certain inversions and a few minor translocations, these two chromosomes (X₂ and the 3rd) still look alike as polytene elements. However, in hybrid males pairing of the two chromosomes, the X₂ and 3rd, is rare, while in female hybrids it occurs frequently. — ³H-TdR labeling shows that while the X₂ and 3rd chromosomes replicate synchronously in hybrid female, in the hybrid male the former completes its replication earlier than the 3rd chromosome, as do the two arms of the X₁ (XL and XR). The frequency and relative intensity of ³H-TdR labeling of each site of the X₂ and that of the 3rd chromosome in hybrid males closely agree with those of the corresponding sites in the X₂ of the miranda male and the 3rd chromosome of the persimilis male (or female), respectively. The results suggest that timing and rate of replication of the X₂ are determined autonomously and follow the pattern in the respective parental species.     

Breeding for resistance to downy mildews and stalk rots in maize

Summary The present review includes information on distribution, symptoms, inoculation techniques, disease rating, sources of resistance, genetics of resistance, breeding approaches for resistance, and the present status of resistance breeding with respect to Sclerophthora and Peronosclerospora downy mildews and Erwinia, Cephalosporium and Fusarium stalk rots. Some suggestions highlighting research gaps pertinent to future breeding strategies are mentioned.Publication No. 2993, Experiment Station, GB Pant University of Agriculture and Technology, Pantnagar, India     

Aliphatic compounds from Costus speciosus roots

Two new compounds G and H isolated from the roots of Costus speciosus have been characterized as 8-hydroxytriacontan-25-one and Me tritriacontanoat     

Subsoil gravel horizon and maize root growth

Summary A series of factoral experiments involving the effects of gravel concentration in the subsoil horizon, the effect of inter-gravel bulk density, the depth of the surface soil above the gravel horizon and the interaction between soil moisture regime and gravel concentration, on growth and development of maize roots were conducted in the greenhouse. Increasing sub soil gravel concentration decreased the total porosity and the available waterholding capacity. Though the root growth of maize seedlings was adversely affected by gravel concentration above 20 per cent, lower concentration of gravels had a beneficial effect on roots. The root development and the leaf concentration of N, P and K improved with increasing depth of surface soil above the gravel horizon. The symptoms of mechanical impedance, such as thickening of root tips and profuse branching behind the tip were commonly observed on the root axis penetrating the gravelly horizon. re]19750916     

Differential reduction of morphine-withdrawal body shakes by butaclamol enantiomers

Rats withdrawn from continuous morphine infusion showed reliable occurrence of withdrawal body shakes. This sign of narcotic withdrawal was inhibited by the neuroleptic drug, (+) butaclamol. (?) Butaclamol was inactive. (+) Butaclamol activity was not antagonized by naloxone (5 mg/kg). The anti-withdrawal mechanism of (+) butaclamol is discussed in terms of effects on dopamine and narcotic receptors.The butyrophenone neuroleptic, haloperidol, has been used successfully to reduce signs of narcotic withdrawal in laboratory animals (1–4) and human addicts (5). Other neuroleptics of the butyrophenone type also show anti-withdrawal action (6, 7). The mechanism of action of these neuroleptics in blocking narcotic withdrawal is not understood. Butaclamol is a new neuroleptic drug that is available in two enantiomers and only (+) butaclamol possesses neuroleptic activity (8–10). Because of its demonstrated stereo-specificity in producing its pharmacological action, we employed this drug to establish specificity of action of neuroleptics in blocking narcotic withdrawal.     

Pesticides induced changes in circulating thyroid hormones in the freshwater catfish Clarias batrachus.

1. Effects of endosulfan, malathion and carbaryl on circulating T4, T3 and T3/T4 ratio in the freshwater catfish, C. batrachus have been studied during reproductively active phases, i.e. vitellogenic and post-vitellogenic phases of its annual reproductive cycle. 2. Endosulfan provoked a significant increase in T4 and a decrease in T3 as well as the T3/T4 ratio. 3. Malathion decreased T3 and T3/T4 ratio without altering the level of T4 in circulation. 4. Carbaryl caused a decline in the level of T4 and an elevation in T3 and T3/T4 ratio.