Intermittent or Continuous Therapy of Experimental Meningitis Due to Streptococcus pneumoniae in Rabbits: Preliminary Observations on the Postantibiotic Effect in Vivo

The relative effectiveness of bolus vs. constant intravenous administration of equivalent doses of penicillin G in killing bacteria in vivo was studied in a rabbit model of meningitis due to Streptococcus pneumoniae. Samples of cerebrospinal fluid (CSF) and serum were obtained from 30 rabbits at intervals of ⩽8 hr after treatment for determination of antibiotic concentrations and titers of viable bacteria in the CSF. When penicillin G was given by continuous infusion (105 units/hr after an initial l05-unit loading dose), concentrations of drug in serum and CSF reached a steady state in 1 hr. With intermittent bolus administration of 4 × 105 units every 4 hr, higher peak and lower trough concentrations were achieved, and these concentrations paralleled those in the CSF. Although an initial acceleration in bactericidal rate was observed with the bolus infusion between the first and second hour of therapy, after the second hour the rate of bacterial killing was identical for the two methods of administration. The duration of therapy required for sterilization of the CSF was dependent only on the bacterial count before treatment and not on the mode of drug administration. The effect of single bolus intravenous administration of ampicillin was examined in experimental pneumococcal meningitis. Ampicillin was given at various dosages (3.25-62.5 mg/kg), and frequent samples of CSF were obtained for determination of concentrations of pneumococci and ampicillin. A long postantibiotic effect was observed in the CSF of all animals, and this effect consistently was longer than that observed in vitr

The Effects Of Acute Resistance Exercise On Dual-Energy X-Ray Absorptiometry Measure Of Body Composition

Dual Energy X-Ray Absorptiometry (DXA) is a reference laboratory method for estimating body composition but there are questions concerning the pre-testing guidelines that should be followed to increase validity and reliability of this methodology. PURPOSE: The purpose of this study was to determine if acute, localized resistance exercise disrupts the validity of DXA total body composition estimates. METHODS: In a crossover design, 18 healthy, resistance-trained, college-aged adults, including 7 females (age: 22.7 ± 1.9 y; height: 165.4 ± 8.4 cm; body mass: 62.1 ± 10.9 kg; body fat: 25.9 ± 7.3%) and 11 males (age: 24.2 ± 4.1 y; height: 180.0 ± 5.1 cm; body mass: 90.2 ± 9.5 kg; body fat: 18.7 ± 7.2%) completed three conditions in a randomized order: lower-body resistance exercise (RELOWER), upper-body resistance exercise (REUPPER), and rest (REST). The resistance exercise (RE) protocol consisted of a RE warm-up consisting of 2 sets of 12-15 repetitions of 3 upper-body exercises (upper), or 3 lower-body exercises (lower) or nothing (rest). The RE circuit consisted of 5 sets of 10 repetitions per exercise, with 1-minute rest intervals between circuits. A DXA scan was performed immediately before exercise and at 60 minutes post exercise. DXA estimates of fat mass (FM) and fat-free mass (FFM; calculated as lean soft tissue plus bone mineral content) were analyzed using 3 x 2 (condition x time) analysis of variance with repeated measures, follow-up pairwise comparisons, and evaluation of the partial eta-squared (ηp2) effect sizes. RESULTS: Pre-exercise FM and FFM did not differ between conditions (0.2 to 0.4 kg; p \u3e 0.14 for all). For FM, no statistically significant interaction or main effects were present (interaction: p=0.80, ηp2=0.01; time main effect: p=0.14, ηp2=0.12; condition main effect: p=0.92, ηp2=0.01). For FFM, no statistically significant interaction (p=0.13, ηp2=0.12) or condition main effect (p=0.56, ηp2=0.03) was present. However, a statistically significant time main effect was present (p=0.009, ηp2=0.34). Pairwise comparisons indicated that post-condition FFM estimates were 0.20 ± 0.07 kg lower than pre-condition values in all conditions combined. CONCLUSION: No differences were seen among conditions, indicating that DXA total body composition estimates may be relatively robust to the effects of acute, localized RE. However, investigation of segmental estimates is warranted due to RE-induced blood flow redistributio

A Simulation Model of Sustained-Yield Harvest for Northern Bobwhite in South Texas

Recommended sustainable harvest rates for northern bobwhite (Colinus virginianus) vary greatly and range from 25% to 70% of the prehunt population. Because northern bobwhite populations have declined across their geographic range, determining sustainable harvest levels is critical for effective management. Our objectives were to use simulation modeling to identify sustainable rates of bobwhite harvest, probability of population persistence, and minimum viable population estimates. We also conducted a sensitivity analysis to evaluate the impacts of harvest on northern bobwhite populations in Texas, USA. We constructed a simulation model using Program STELLA 9.0 for a hypothetical northern bobwhite population on 800 ha in the South Texas Plains USA and modeled population dynamics to 100 years over a range of harvest rates (0–40%). A 20% harvest rate produced the greatest average yields (mean ± standard error = 231 ± 10 bobwhites harvested/year). Given a quasi-extinction criterion of ≤40 bobwhites (≤0.05 bobwhite/ha), a 30% harvest rate resulted in a high probability of quasi-extinction (PE = 0.75) within 47.8 ± 2.3 years. A 40% harvest rate was not sustainable (PE = 1.0), with quasi-extinction occurring within 15.5 ± 2.6 years. Harvesting northern bobwhite populations in the South Texas Plains at rates of 20−25% of the prehunt population should maximize long-term harvest while minimizing the probability of population extinction. Spring densities of 0.60−0.80 bobwhite/ha may represent minimum viable spring densities for northern bobwhite populations in the South Texas Plains as these are the densities associated with sustainable 20-25% harvest rates. Harvest rates \u3e30% are likely to be excessive with respect to long-term population persistence for northern bobwhite populations in the South Texas Plains

Field Application of Sustained-Yield Harvest Management for Northern Bobwhite in Texas

Sustained-yield harvest (SYH) is considered a potentially viable strategy for managing harvest of northern bobwhites (Colinus virginianus). However, application of SYH has not been evaluated for northern bobwhites. We evaluated the application of using SYH as a harvest management strategy for bobwhite during the 2007 2008 and 2008 2009 hunting seasons in 2 ecoregions of Texas (Rolling Plains, South Texas Plains). We collected field data at 3 study sites/ecoregion (900 1,900 ha each; 2 hunted sites and 1 control) to estimate 4 demographic parameters (fall and spring density, overwinter survival in the absence of hunting, and harvest rate). We used these data to parameterize the additive harvest model for bobwhites and compare predictions of spring abundance of the model with field estimates. The additive harvest model, compared to field estimates, consistently underestimated spring population density (mean 6 SE) by 55.7 6 17.8% (2007 2008) and 34.1 6 4.9% (2008 2009) in the Rolling Plains, and by 26.4 6 25.3% (2007 2008) and 49.1 6 2.1% (2008 2009) in the South Texas Plains. Implementing SYH in the field, despite its potential benefits, will be challenging given the need for reliable estimates of 3 key population parameters (fall and spring density, and natural mortality in the absence of hunting) and the high variation often associated with them. Conservative harvest prescriptions based on the lower 95% CIs of fall density estimates may permit sustainable harvest despite variation in density estimates

Population Response of Three Quail Species to Habitat Restoration in South Texas

Maintaining and increasing usable space is paramount for maintaining and increasing wild quail. Aside from weather and other factors that can temporarily reduce densities, range-wide, no factor has as much influence on quail populations as the amount of habitat present across the landscape. In the field of quail management, ‘‘bad news’’ is the norm, as many articles begin by explaining how a select species has declined. Here we provide good news and use 4 empirical examples of population increases for 3 quail species following creation of usable space and restoration of patch connectivity. From 2008–2014, a suite of independent projects aimed at increasing usable space for quail was initiated across South Texas. These projects included 3 focused on northern bobwhites (Colinus virginianus), 1 focused on scaled quail (Callipepla squamata), and 1 landowner-executed project focused on Montezuma quail (Cyrtonyx montezumae). Through the correction of attributes limiting habitat, bobwhite numbers increased 22–378% across 2 studies. On one particular study site, native grassland restoration resulted in the colonization of bobwhites from adjacent areas to 1 bobwhite/1.2 ha from nearly 0. For scaled quail in South Texas, reducing buffelgrass standing crop via grazing from about 2,240 kg/ha to 1,008 kg/ha resulted in the recolonization of a previously unoccupied habitat patch to a density of 1 scaled quail/6 ha. Finally, clearing monotypic stands of the invasive native plant, ash juniper (Juniperus ashei) in the Edwards Plateau of Texas, resulted in the reestablishment of native grasses and forbs and thus recolonization by Montezuma quail from nearby areas. Although habitat restoration and management can be a painstaking and lengthy process, addressing limiting factors to quail occupancy is the only known way to increase wild quail populations. We hope that highlighting these particular studies will provide inspiration to those interested in restoring and increasing quail across the US

Using NMR-based metabolomics to evaluate postprandial urinary responses following consumption of minimally processed wheat bran or wheat aleurone by men and women

Wheat bran, and especially wheat aleurone fraction, are concentrated sources of a wide range of components which may contribute to the health benefits associated with higher consumption of whole-grain foods. This study used NMR metabolomics to evaluate urine samples from baseline at one and two hours postprandially, following the consumption of minimally processed bran, aleurone or control by 14 participants (7 Females; 7 Males) in a randomized crossover trial. The methodology discriminated between the urinary responses of control, and bran and aleurone, but not between the two fractions. Compared to control, consumption of aleurone or bran led to significantly and substantially higher urinary concentrations of lactate, alanine, N-acetylaspartate acid and N-acetylaspartylglutamate and significantly and substantially lower urinary betaine concentrations at one and two hours postprandially. There were sex related differences in urinary metabolite profiles with generally higher hippurate and citrate and lower betaine in females compared to males. Overall, this postprandial study suggests that acute consumption of bran or aleurone is associated with a number of physiological effects that may impact on energy metabolism and which are consistent with longer term human and animal metabolomic studies that used whole-grain wheat diets or wheat fractions.peer-reviewe

The Effects Of Acute Resistance Exercise On Bioelectrical Impedance Analysis Measures Of Body Composition

Bioelectrical Impedance Analysis (BIA) is a popular method of body composition assessment; however, validity of BIA is thought to be highly dependent on adhering to pre-test criteria, including the abstinence from exercise prior to testing. PURPOSE: The purpose of this study was to determine if acute, localized resistance exercise (RE) compromises the validity of BIA total body composition estimates. METHODS: In a crossover design, 16 healthy, resistance trained adults, including 7 females (age: 22.7 ± 1.9 y; height: 165.4 ± 8.4 cm; body mass: 62.1 ± 10.9 kg; body fat: 25.9 ± 7.3%) and 9 males (age: 24.3 ± 3.6 y; height: 179.1 ± 5.1 cm; body mass: 88.0 ± 7.6 kg; body fat: 18.4 ± 6.6%) completed three conditions in a randomized order: lower-body resistance exercise (RELOWER), upper-body resistance exercise (REUPPER), and rest (REST). The RE protocol consisted of a warm-up consisting of 2 sets of 12-15 repetitions of 3 upper-body exercises (upper) or 3 lower-body exercises (lower), followed by 5 sets of 10 repetitions per exercise, with 1-minute rest intervals. The REST condition involved no exercise. BIA (InBody 770) was completed immediately pre and post-exercise and at 15-, 30-, and 60-minutes post-exercise. BIA estimates of fat mass (FM) and fat-free mass (FFM) were analyzed using 3 x 5 (condition x time) analysis of variance with repeated measures, follow-up pairwise comparisons, and evaluation of the partial eta-squared (ηp2) effect sizes. RESULTS: Pre-exercise FM and FFM did not differ between conditions (0.1 to 0.4 kg; p \u3e 0.4 for all). Condition x time interactions were present for both FM (pp2 =0.48) and FFM (pp2 =0.45). Pairwise comparisons indicated that FM was lower in the REUPPER condition as compared to both REST (1.5 kg; pLOWER (1.3 kg; pUPPER condition as compared to both REST (1.3 kg; pLOWER (0.9 kg; pUPPER as compared to REST (1.0 kg; p=0.005) but no longer differed between REUPPER and RELOWER (0.4 kg; p=0.44). CONCLUSION: These data indicate that acute upper-body RE compromises the validity of BIA total body composition estimates compared to REST and lower-body RE and reinforces exercise abstinence as a pre-test consideration. Further exploration of the effects on segmental body composition data is warranted

Genetic Structure and Diversity in South Texas Bobwhites: Implications for Conservation

The northern bobwhite (Colinus virginianus) has experienced range-wide declines in population size and reductions in geographic range during the last century. Declines in northern bobwhite population size and geographic distribution continue to occur despite vigorous conservation and research efforts directed at sustaining and enhancing populations. Viable populations of northern bobwhite have persisted only in areas with large expanses of relatively contiguous habitat, such as southern Texas, parts of Oklahoma, Kansas, and areas in southern Georgia and northern Florida. The decline of northern bobwhite populations is often associated with changes in land- use practices, including proliferation of intensive agriculture and fire suppression, which have altered, removed, or fragmented northern bobwhite habitat. Typically, the effects of changes in land use on northern bobwhites are regional in scale, given the large geographic extent which current agricultural land-use practices, such as farming and timber production, occur. It is clear that precipitation and land use affect regional population trends, but consideration of northern bobwhite population dynamics has remained confined to the local scale. Thus, the specific manner in which land-use changes have affected populations of northern bobwhites is unknown. We investigated the genetics and population structure of northern bobwhites at the landscape scale to learn if bobwhites function as metapopulations. Dispersal and exchange in a metapopulation system are critical to the long-term maintenance of populations; if interrupted, the entire network of populations might collapse. We sampled hunter-harvested northern bobwhites during 2004 to 2007 from 24 sites in South Texas, a region containing large areas of contiguous habitat where populations of northern bobwhites have been relatively stable. We extracted DNA and used bi-parentally and maternally inherited genetic markers to compare genetic structure and diversity among populations. We genotyped 567 individuals at 7 DNA microsatellite loci and sequenced 353 bp of the mtDNA control region for 190 individuals. Genetic diversity was high for microsatellite loci and mtDNA haplotypes (HO 1⁄4 0.58; H 1⁄4 0.88, respectively), and did not differ among populations. We observed little population structure across the geographic region (microsatellite FST 1⁄4 0.01; mtDNA theta 1⁄4 0.037), and Fisher exact tests of population differentiation were not statistically significant. Spatial autocorrelation analysis of the microsatellite data set revealed a positive correlation between Moran’s I and geographic distance out to .50 km. Our genetic data are surprising for an avian species that is considered relatively sedentary and a short-distance disperser. South Texas populations of northern bobwhites had high levels of genetic variation and were genetically similar across a broad region. Population genetics theory predicts that genetic diversity and similarity among local populations in a metapopulation are influenced by the rate of dispersal (gene flow). Life history theory predicts species with high turnover rates, such as northern bobwhite, should be good dispersers. The region-wide genetic similarity among populations of northern bobwhites implies dispersal may be more important in the population dynamics of the species than previous studies have indicated. We hypothesize that disruption of dispersal by habitat fragmentation may explain the overall decline of northern bobwhite populations in some regions. This may explain why patches of suitable habitat in fragmented landscapes go unoccupied by northern bobwhites. Our results lend additional support to recent calls for regional-scale management of this declining species