Niche divergence and lineage diversification among closely related Sistrurus rattlesnakes.

Comparing niche divergence among closely related taxa can yield important insights into the ecological distinctiveness of genetically similar forms, and identify the processes that are responsible for diversification in such organisms. Here, we apply newly developed techniques for analysing niche divergence to assess how ecologically distinct a group of closely related rattlesnakes (Sistrurus sp.) are and to explore the role that niche divergence may have played in their diversification. We find that all taxa even the most recently evolved subspecies (approximately 100,000 years old) are now ecologically distinct, implying a role for ecology in the diversification process. Statistical analysis based on comparisons with null models show that niche divergence between forms is more common than niche conservation. Finally, there is nonlinear relationship between phylogenetic and niche divergence in this group whereby niche divergence develops more rapidly between recently diverged subspecies than more distantly related forms. Overall, our results argue that ecology may play an important role in the diversification process in these snakes.

Resistance exercise and lipoproteins in postmenopausal women.

The specific aims of this study were to quantify the effects of 12 weeks of resistance training, as well as a single session of resistance exercise on lipids and lipoproteins in obese, postmenopausal women. 21 obese, postmenopausal women, not on hormone replacement therapy (age=65.9 ± 0.5 yr; BMI=32.7 ± 0.8 kg/m(2)), were randomly assigned to control (n=12) and exercise (n=9) groups matched for age and BMI. For 12 weeks, 3 days/week, the exercise group performed 10 whole body resistance exercises (3 sets at 8-RM). Fasting (10 h) blood samples were collected immediately prior to and 24 h after the first and last exercise and control session. Serum was assayed for concentrations of total cholesterol, triglycerides, LDL-C, HDL-C, HDL 2-C, HDL 3-C, non-HDL-C and TC:HDL and LDL:HDL ratios. The exercise group exhibited a significant (P<0.01) improvement in muscular strength, but no change in BMI, body mass or body composition post-training. Total cholesterol, LDL-C and non-HDL-C were significantly (P<0.05) lower in the exercise compared to the control group following the 12 weeks of resistance training. Whole body resistance training provides obese, postmenopausal women a non-pharmacological approach for the reduction of lipid and lipoprotein-cholesterol concentrations.

Household exposures to drinking water disinfection by-products: whole blood trihalomethane levels.

Exposure to drinking water disinfection by-products (DBPs), such as trihalomethanes (THMs), has been associated with bladder and colorectal cancer in humans. Exposure to DBPs has typically been determined by examining historical water treatment records and reconstructing study participants' water consumption histories. However, other exposure routes, such as dermal absorption and inhalation, may be important components of an individual's total exposure to drinking water DBPs. In this study, we examined individuals' exposure to THMs through drinking, showering, or bathing in tap water. Thirty-one adult volunteers showered with tap water for 10 min (n = 11), bathed for 10 min in a bathtub filled with tap water (n = 10), or drank 1 l of tap water during a 10 min time period (n = 10). Participants provided three 10 ml blood samples: one sample immediately before the exposure; one sample 10 min after the exposure ended; and one sample 30 min (for shower and tub exposure) or 1 h ( for ingestion) after the exposure ended. A sample of the water (from the tap, from the bath, or from the shower) was collected for each participant. We analyzed water samples and whole blood for THMs (bromoform, bromodichloromethane, dibromochloromethane, and chloroform) using a purge-and-trap/gas chromatography/mass spectrometry method with detection limits in the parts-per-quadrillion range. The highest levels of THMs were found in the blood samples from people who took 10 min showers, whereas the lowest levels were found in the blood samples from people who drank 1 l of water in 10 min. The results from this study indicate that household activities such as bathing and showering are important routes for human exposure to THMs.

Bulk analysis of tobacco and cigarettes by magnetic resonance imaging.

Proton magnetic resonance imaging of tobacco blends in cigarette rods was investigated to assess the feasibility of various imaging protocols to characterize and quantify the structure and composition of multiphase plant materials in situ. The protocols used to characterize the rigid molecular components (plant cell wall) included single-point imaging (SPI) and a variant experiment, single-point ramped imaging with T(1) enhancement (SPRITE). Both 1D profiles, radially averaged along the length of a cigarette, and 2D maps of proton spin density and relaxation (T(2)) were acquired. Mobile components (tobacco waxes and water) were examined via conventional spin-echo imaging techniques, with 1D, 2D, and 3D data being acquired. Spin-spin relaxation times (T(2)), apparent spin-spin relaxation (T(2)), and spin-lattice (T(1)) relaxation times were measured for selected samples.

The use of solid-phase microextraction in conjunction with a benchtop quadrupole mass spectrometer for the analysis of volatile organic compounds in human blood at the low parts-per-trillion level.

The analysis of volatile organic compounds (VOCs) in whole human blood at the low parts-per-trillion level has until recently required the use of a high-resolution mass spectrometer to obtain the specificity and detection limits required for epidemiological studies of VOC exposure in the general public. Because of the expense and expertise required to operate and maintain a high-resolution instrument, the applicability of this method has been limited. These limitations are overcome in a new method using automated headspace solid-phase microextraction (SPME) in conjunction with a gas chromatograph and a benchtop quadrupole mass spectrometer. A combination of SPME and multiple single-ion monitoring minimizes the interferences and chemical noise associated with whole blood samples. This method permits the analysis of 10 VOCs in human blood while simplifying the sample preparation and reducing the possible exposure of the analyst to blood aerosols. Twelve samples can be run successively in a fully automated mode, thus eliminating the need for operator attention. Detection limits are below 50 ppt (pg/mL) for a majority of the VOCs tested with a 5-mL sample.

Review of common adverse effects of selected antiarrhythmic drugs.

The management of cardiac arrhythmias has changed dramatically over the past several years. New drugs and devices are now available to treat various arrhythmias. Many new agents have been developed that rely on different electrophysiologic mechanisms to elicit their effect on the heart rhythm. Though often effective, these drugs also pose a risk because all of them have a variety of potential adverse effects associated with their use. Many of these adverse reactions are common to all antiarrhythmic drugs, whereas others are unique to particular agents. This review discusses the notable adverse effects of selected antiarrhythmic drugs.

Measurement of volatile organic compounds in human blood.

Volatile organic compounds (VOCs) are an important public health problem throughout the developed world. Many important questions remain to be addressed in assessing exposure to these compounds. Because they are ubiquitous and highly volatile, special techniques must be applied in the analytical determination of VOCs. The analytical methodology chosen to measure toxicants in biological materials must be well validated and carefully carried out; poor quality assurance can lead to invalid results that can have a direct bearing on treating exposed persons. The pharmacokinetics of VOCs show that most of the internal dose of these compounds is quickly eliminated, but there is a fraction that is only slowly removed, and these compounds may bioaccumulate. VOCs are found in the general population at the high parts-per-trillion range, but some people with much higher levels have apparently been exposed to VOC sources away from the workplace. Smoking is the most significant confounder to internal dose levels of VOCs and must be considered when evaluating suspected cases of exposure.

Accelerating the culture change!

Exide Electronics, a major supplier of uninterruptible power system equipment, embarked on a journey of changing a culture to improve quality, enhance customer responsiveness, and reduce costs. This case study examines the evolution of change over a period of seven years, with particular emphasis on the most recent years, 1992 through 1995. The article focuses on the Raleigh plant operations and describes how each succeeding year built on the successes and fixed the shortcomings of the prior years to accelerate the culture change, including corrective action and continuous improvement processes, organizational structures, expectations, goals, achievements, and pitfalls. The real challenge to changing the culture was structuring a dynamic approach to accelerate change! The presentation also examines how the evolutionary process itself can be created and accelerated through ongoing communication, regular feedback of progress and goals, constant evaluation and direction of the process, and measuring and paying for performance.

Clinical manifestations of transdermal scopolamine addiction.

Transdermal scopolamine patches have been extensively prescribed for nonspecific dizziness and vestibular disorders. Patient response may be favorable and side effects are generally limited to xerostomia and blurred vision. However, subtle dependency and outright addiction may develop. Tapered reduction and drug elimination will suffice to eliminate the dependency. However, hospitalization may be necessary to treat severe cases of physiological chemical dependency. Long-term use of transdermal scopolamine patches carries a risk of chemical dependency. Prescribing physicians should review and heed the manufacturer's recommended use.

Treatment of vacutainers for use in the analysis of volatile organic compounds in human blood at the low parts-per-trillion level.

Vacutainers that are routinely used for blood collection contain significant amounts of volatile organic compounds (VOCs). These VOCs interfere with the low parts-per-trillion analysis of VOCs in whole blood either by causing false positives or by masking the presence of VOCs because of high background levels. Benzene, bromoform, ethylbenzene, m/p-xylene, o-xylene, styrene, and various hydrocarbons are the most significant sources of VOC contamination present in the vacutainers. A method of removing VOCs from 10-mL gray-top vacutainers is presented. This method uses a combination of heat and vacuum to reduce the VOCs to levels compatible with low parts-per-trillion analysis of VOCs in whole blood.

Dosing guidelines for foscarnet and trimetrexate.

The P & T Committee at Trinity Lutheran Hospital, a 320-bed, community/teaching hospital in Kansas City, MO, has developed dosing and monitoring guidelines for foscarnet sodium (Foscavir) and trimetrexate glucuronate (Neutrexin)--two drugs used to treat patients with opportunistic infections associated with the human immunodeficiency virus (HIV). Presented in this Experience Brief is a short discussion of these drugs, the rationale for guideline development, and the actual dosing and monitoring protocols devised.

Measurement of methyl tert-butyl ether and tert-butyl alcohol in human blood by purge-and-trap gas chromatography-mass spectrometry using an isotope-dilution method.

We developed an isotope-dilution method for measuring methyl tert-butyl ether (MTBE) and tert-butyl alcohol (TBA) in whole human blood using a purge-and-trap gas chromatographic-mass spectrometric method. The labeled analogues for MTBE and TBA were [2H12]methyl tert-butyl ether and [2H9]-tert-butyl alcohol, respectively. Volatiles were removed from the blood by direct helium purging of the liquid; were trapped on a Tenax trap; and were desorbed, cryofocused, and chromatographed on a DB-624 capillary column that was connected directly to the ion source of a mass spectrometer. Detection was by mass analysis using a double-focusing magnetic-sector mass spectrometer operating in the full-scan mode at the medium mass resolution of 3000. For the isotope-dilution method, the minimum detection limits in blood (5-10 mL) are 0.01 microgram/L for MTBE and 0.06 microgram/L for TBA. The isotope-dilution method proved to be a big improvement in recovery, reproducibility, and sensitivity over our previous analytical method, which used the labeled ketone, [4-2H3]-2-butanone, as the internal standard for both MTBE and TBA. The isotope-dilution method has sufficient sensitivity for monitoring blood levels of MTBE and TBA in populations exposed to oxygenated fuels containing MTBE.

Production and oxidation of indole by Haemophilus influenzae.

During growth in high concentrations of iron nitrate, H. influenzae produces compounds reactive in biochemical assays for hydroxamates. Mixing experiments established that nitrate was responsible for inducing these compounds. Analysis by 1H and 13C NMR and high resolution mass spectrometry identified the active species as 2,2-bis(3'-indolyl)indoxyl. Bacterial production of the latter compound has been previously observed only in Pseudomonas aureofaciens. A mutant defective in the production of 2,2-bis(3'-indolyl)indoxyl was constructed by marker insertion. The formation of indole and 2,2-bis (3'-indolyl)indoxyl was quantitated by reverse-phase high pressure liquid chromatography during growth in high concentrations of nitrate. The mutant produced high concentrations of indole, but only minimal amounts of 2,2-bis(3'-indolyl)indoxyl, and also proved to be defective in nitrate reduction. These data suggest that indole may function as an electron donor for nitrate reductase in H. influenzae.

Blood concentrations of volatile organic compounds in a nonoccupationally exposed US population and in groups with suspected exposure.

Exposure to certain volatile organic compounds (VOCs) commonly occurs in industrialized countries. We developed a method for measuring 32 VOCs in 10 mL of whole blood at low concentration. We used this method to determine the internal dose of these compounds in 600 or more people in the US who participated in the Third National Health and Nutrition Examination Survey. From our study results, we established a reference range for these VOCs in the general population of the US. We found detectable concentrations of 1,1,1-trichloroethane, 1,4-dichlorobenzene, 2-butanone, acetone, benzene, chloroform, ethylbenzene, m,p-xylene, styrene, tetrachloroethane, and toluene in most of the blood samples of nonoccupationally exposed persons. The accuracy of VOC evaluations depends on the ability of investigators to make sensitive and reproducible measurements of low concentrations of VOCs and to eliminate all sources of interference and contamination.

Binding of human hemoglobin by Haemophilus influenzae.

Binding of biotinylated human hemoglobin to Haemophilus influenzae was detected when organisms were grown in heme-deplete, but not heme-replete, conditions. Hemoglobin binding was completely inhibited by a 100-fold excess of unlabelled human hemoglobin or human hemoglobin complexed with human haptoglobin. Binding was only partially inhibited by rat hemoglobin, bovine hemoglobin, human globin, and bovine globin, and not at all by heme, human serum albumin, bovine serum albumin, human transferrin, or myoglobin. Hemoglobin binding was saturable at 16-20 ng of hemoglobin per 10(9) cfu. Binding of human hemoglobin was detected in serotypes a-f and serologically non-typable strains of H. influenzae, as well as Haemophilus haemolyticus but not Haemophilus parainfluenzae, Haemophilus aphrophilus, Haemophilus parahaemolyticus, or Escherichia coli.

Lignification in cell suspension cultures of Pinus taeda. In situ characterization of a gymnosperm lignin.

Pinus taeda suspension cultures grown in medium containing 2,4-dichlorophenoxyacetic acid showed only primary cell wall formation and essentially no lignification, as determined by histochemical, ultrastructural, chemical, and NMR spectroscopic analyses. However, these cultures maintained a functional phenylpropanoid pathway as demonstrated by formation of the lignans (-)-matairesinol and (-)-pinoresinol. Administration of [1-13C]Phe to these cultures, followed by solid-state carbon-13 NMR spectral analysis of their cell walls, demonstrated that the phenylalanine incorporated into the cell wall matrix was primarily as protein, rather than lignin. Successive transfer of the 2,4-dichlorophenoxyacetic acid-grown cultures to alpha-naphthaleneacetic acid-containing medium induced cell wall thickening concomitant with lignification. The presence of lignin was confirmed by histochemical, ultrastructural, chemical, biochemical, and NMR spectroscopic analyses. Specific labeling of the lignin polymer in situ with [1-13C]-, [2-13C]-, and [3-13C]Phe and analysis of the cell wall preparations by solid-state carbon-13 NMR spectroscopy permitted the first direct determination of the in situ bonding patterns in a gymnosperm lignin. Several dominant interunit linkages were observed, including beta-O-aryl, furanofuran, phenylcoumarin, and phenolic-linked monolignols, consistent with those predicted but hitherto not proven. Finally, milled wood lignin derivatives prepared from these 13C-specifically enriched lignin tissues gave a relatively high fidelity copy of the native lignin.

Dependence of the plasma triacylglycerol-lowering effect of fish oil on insulin replacement in streptozotocin diabetic rats.

Streptozotocin diabetic rats, with and without insulin replacement, and sham-injected controls were fed a high-fat (30% of energy) menhaden oil (MO) or corn oil (CO) diet for 2 weeks. After an overnight fast, plasma and livers were collected for analysis of insulin, glucose, triacylglycerol, cholesterol and glucose-6-phosphate dehydrogenase activity. Streptozotocin treatment resulted in decreased plasma insulin and elevated glucose. MO-feeding to insulin-replaced diabetic rats resulted in higher insulin and lower glucose levels compared to the respective CO-fed rats, suggesting decreased hepatic insulin extraction and greater peripheral utilization of glucose with MO. Plasma triacylglycerol and cholesterol, and hepatic glucose-6-phosphate dehydrogenase activity were reduced in MO-fed vs. CO-fed control rats. These effects of MO were prevented in the diabetic rats but were restored by insulin replacement. We conclude from our data that the presence of insulin is required to observe at least some of the effects of fish oil (FO). To explain our observations we propose that many of the effects of FO on hepatic metabolism are mediated by an inhibition of insulin action in the liver, thus providing a possible central mechanism for the regulation of hepatic lipid metabolism by dietary FO.

Reduction in triacylglycerol levels by fish oil correlates with free fatty acid levels in ad libitum fed rats.

Rats were fed (for 2 or 6 wk) purified diets containing lard (LD) or menhaden oil (MO) at two levels of dietary fat, i.e., at 11.5 and 20.8% of energy in the low fat (LF) and the medium fat (MF) diets, respectively. Following the diet period, rats were sacrificed after either an overnight fast or after uninterrupted ad libitum feeding. The studies were designed to investigate the dependence of our previously reported effects of MO, i.e. the reduction of plasma free fatty acid (FFA) levels and accumulation of hepatic triacylglycerols, on the dietary fat concentration and the nutritional state of the animal at the time of sacrifice. Reductions in plasma triacylglycerol and cholesterol levels in MO-fed relative to LD-fed rats were observed under all conditions. FFA levels were consistently reduced by MO-feeding at both dietary fat concentrations, but only when blood was sampled from ad libitum fed rats. Under these conditions there was a significant positive relationship between plasma FFA and triacylglycerol concentrations. Reduction in plasma FFA levels may be an additional mechanism associated with the triacylglycerol-lowering effect of fish oil (FO). The LF and MF MO diets caused a rise in plasma glucose levels with no significant change in insulin concentration, indicating that the reduction of FFA by MO was not related to changes in insulin concentration or insulin sensitivity. The MO diets had no effect on skeletal muscle or epididymal adipose tissue lipoprotein lipase activity, demonstrating that catabolism of triacylglycerol-rich lipoproteins contributes little, if any, to the MO-dependent reductions of plasma triacylglycerol and FFA.(ABSTRACT TRUNCATED AT 250 WORDS)