Molecular genetic analysis of volatile-anesthetic action.

The mechanism(s) and site(s) of action of volatile inhaled anesthetics are unknown in spite of the clinical use of these agents for more than 150 years. In the present study, the model eukaryote Saccharomyces cerevisiae was used to investigate the action of anesthetic agents because of its powerful molecular genetics. It was found that growth of yeast cells is inhibited by the five common volatile anesthetics tested (isoflurane, halothane, enflurane, sevoflurane, and methoxyflurane). Growth inhibition by the agents is relatively rapid and reversible. The potency of these compounds as yeast growth inhibitors directly correlates with their lipophilicity as is predicted by the Meyer-Overton relationship, which directly correlates anesthetic potency of agents and their lipophilicity. The effects of isoflurane on yeast cells were characterized in the most detail. Yeast cells survive at least 48 h in a concentration of isoflurane that inhibits colony formation. Mutants resistant to the growth-inhibitory effects of isoflurane are readily selected. The gene identified by one of these mutations, zzz4-1, has been cloned and characterized. The predicted ZZZ4 gene product has extensive homology to phospholipase A2-activating protein, a GO effector protein of mice. Both zzz4-1 and a deletion of ZZZ4 confer resistance to all five of the agents tested, suggesting that signal transduction may be involved in the response of these cells to volatile anesthetics.

Historical review of termite activity at forest service termiticide test sites from 1971 to 2004.

The U.S. Forest Service has a long history of providing termiticide efficacy data used for product registration and labeling. Four primary test sites (Arizona and Florida, Mississippi, and South Carolina [hereafter southeast]) have been used for this purpose. Various parameters of termite attack at water-only control plots were examined in this study to assess the relative pressures of termites at each site. Termiticide studies installed between 1971 and 2001 by using ground board (GB) and concrete slab (CS) test methods were included. GB control plots were attacked 85% of the time in the southeast, about twice the rate observed in Arizona (43%). CS plots were attacked 59-70% of the time in the southeast, significantly higher than in Arizona (43%). Termites were slower to initiate attack at control plots in Arizona compared with the southeast, and they were up to twice as slow at GB controls. Once initial attack began, GB plots were reattacked at higher percentages in the southeast (89-90%) than in Arizona (67%). Reattack at CS plots ranged from 65% in Arizona and South Carolina to 76% in Mississippi. Termites caused less damage to wooden blocks in control plots in Arizona than the southeast. Attack rates at controls generally declined during the 1990s, but these rates have rebounded since 2000, except at CS plots in Arizona and South Carolina. Statistical analysis of attacks at plots treated with chlorpyrifos, cypermethrin, fenvalerate, and permethrin also was undertaken. Time to initial termite attack (failure) of the organophosphate chlorpyrifos was generally shorter in Arizona than in the southeast, whereas time to initial attack in plots treated with one of three pyrethroids (cypermethrin, fenvalerate, and permethrin) was generally longer in Arizona.

Activation of uteroglobin gene expression by progesterone is modulated by uterine-specific promoter-binding proteins.

In a previous study specific protein binding to the uteroglobin (UG) promoter was detected in gel retardation assays using progesterone-dominated rabbit uterine nuclear extract proteins. Those findings have now been extended to reveal the components within that specific shifted band. Southwestern blotting and photoaffinity cross-linking of protein-DNA complexes by UV irradiation demonstrate binding of two proteins with apparent molecular masses of 94 and 115 kDa to a 126-basepair UG gene fragment (UG126-194/-68). To further investigate the tissue- and hormone-specific expression of the UG gene and to relate that specificity to promoter binding, RNA was prepared from rabbit uterus, kidney, and lung after 5 consecutive days of progesterone treatment. Northern blots of total RNA showed an absence of UG expression in kidney, while UG message was detected in uterus and lung. Protein binding to UG promoter DNA was absent in extracts from nuclei of kidney and HeLa cells, where the gene is not expressed, and from lung, where the gene is expressed but not regulated by progesterone. Digestion of the uterine protein-DNA complex using the nuclease activity of phenanthroline-copper ion and DNAase-I revealed two footprints. Protection was similar on both DNA strands, indicating no preference of protein binding to one DNA strand over the other. Taken together, the results provide strong indirect evidence that transcriptional activation of UG gene expression by progesterone requires binding of two additional proteins to UG promoter elements.

Uterus-like mass of the small intestine. Heterotopia or monodermal teratoma?

A 12-year-old girl with multiple lower-intestinal and urogenital tract anomalies and a past history of sacrococcygeal teratoma had an intramural mass of the ileum discovered as an incidental finding at surgery. The predominant mass had the features of the uterine fundus and two smaller contiguous nodules resembled the fallopian tube. A normal uterus and ovaries were observed at surgery. Somewhat similar lesions have been reported in the past in the ovary, ileum, scrotum, and possibly the bladder. Neither the metaplastic nor malformational theories are entirely satisfactory, yet they can be stated for most examples of heterotopias or choristomas.

Effectiveness of combining maternal serum alpha-fetoprotein and hCG in a second-trimester screening program for Down syndrome.

OBJECTIVE: To evaluate the efficacy of combining hCG and alpha-fetoprotein (AFP) with maternal age in a two-analyte maternal serum screening program for Down syndrome. METHODS: A prospective study involved the screening of 12,170 maternal sera from patients at 14-25 weeks of gestation. The risk for Down syndrome at term was calculated from maternal serum hCG and AFP, and maternal age. For women 36 years of age and younger, a risk of 1:307 or greater was considered screen-positive. For women over 36, a risk greater than that a priori was considered screen-positive. False-positive rates and detection rates were compared with those resulting from a screening protocol using only AFP and age. RESULTS: Seven hundred eighty-two sera were initially screen-positive (6.4%). Subsequent sonography decreased this total to 687 (5.6%), and 467 (3.8%) of these patients accepted amniocentesis. Ten cases of Down syndrome and seven other chromosomal abnormalities were detected. Follow-up investigations revealed eight additional Down syndrome cases that were missed by screening. The identification of 18 Down syndrome cases in 12,170 pregnancies corresponds closely with the prediction of 14.1 Down syndrome births (18.2 second-trimester fetuses) in this population calculated from age-dependent risks. The detection rate for Down syndrome was 56% (ten of 18 expected cases). Only five of 18 (28%) would have been detected by AFP and age alone. CONCLUSION: These results support the mathematical model that hCG is the major contributor to the increased sensitivity of multi-analyte screening and demonstrate that screening programs can attain substantial improvement in detection of second-trimester Down syndrome by adding hCG to AFP and age.

Transvalvular left ventricular pressure measurement in the isolated working rat heart.

A method of continuously measuring left ventricular (LV) pressure in an isolated buffer-perfused working rat heart is described. Transvalvular placement of a micromanometer through the aorta is the unique feature of this procedure. Advantages include catheter stability and lack of myocardial trauma. Changes in cardiac function were quantified by exposing hearts to either isoproterenol (10(-9) M) or halothane (1.5% vol/vol). To examine if any obstruction to LV outflow was caused by the micromanometer, cardiac performance was assessed during pullback from the ventricle to the aorta. Complications such as aortic insufficiency and ventricular arrhythmias were also studied. The results indicate that the transvalvular placement of a micromanometer can provide continuous, high-fidelity reproduction of LV pressure in this small-organ preparation. The presence of the micromanometer did not significantly alter cardiac performance, and proper catheter placement was achieved easily in a high percentage (> 90%) of cases.

Decreased maternal serum hCG levels with increasing gravidity and parity.

OBJECTIVE: To investigate the preliminary observation that primigravid women have higher hCG multiples of the median (MoM) than multigravid women. METHODS: An analysis of the effect of gravidity and parity on maternal serum alpha-fetoprotein (MSAFP) and hCG was performed using data from 20,009 consecutive singleton pregnancies of 15-20 weeks' gestation in a maternal serum screening program. RESULTS: The human chorionic gonadotropin MoM for primigravid women was 0.1 MoM higher than for multigravid women. As parity or gravidity increased, maternal serum hCG decreased. The median hCG MoM for nulliparous women was 1.05, compared with 0.94 MoM for para 3 women. The decrease in hCG was similar at each gestational week from 15-20. In contrast, MSAFP and MSAFP MoM were unaffected by parity. Maternal age and race were potential contributing factors to the effect of parity. However, the decrease in hCG MoM with parity was observed within each 5-year increment of maternal age. Similarly, both black and non-black populations displayed decreases in hCG with parity, although black women had a consistently higher MoM in all matched sets. The decrease in hCG MoM with parity was also observed in 50 Down syndrome cases. Correcting patient data for parity resulted in the hCG MoM changing only 2.7% on average. The detection rate for the 50 Down syndrome cases would not have changed. CONCLUSION: The decrease in maternal serum hCG with increasing parity demonstrates that pregnancy history influences the level of maternal serum hCG. Further studies are needed to define the contributing factors, but the impact of parity on Down syndrome screening appears to be small.

A rodent model of focally evoked self-sustaining status epilepticus.

We describe a novel model of status epilepticus produced by the focal application of bicuculline methiodide into the deep prepiriform cortex of rats pretreated with lithium chloride. Three out of eight rats pretreated with one dose of lithium (3 mmol/kg) 24 h prior to induction of seizures by focal bicuculline, and eight out of 12 rats pretreated with two doses of lithium (at 24 and 48 h) prior to seizure induction, exhibited continual uninterrupted convulsive seizure activity (status epilepticus) lasting between 10 min and > 2 h. This status epilepticus which was manifest both behaviorally and electroencephalographically, was sensitive to reversal by diazepam (5 mg/kg i.p.) given as long as 2 h after the onset of sustained status epilepticus. Pilocarpine (25 mg/kg) pretreatment also predisposed to status epilepticus in response to the focal application of bicuculline, but diazepam (5 or 10 mg/kg i.p.) was ineffective in suppressing the status epilepticus in the presence of pilocarpine.

Catastrophic wind damage to North American forests and the potential impact of climate change.

Catastrophic winds from tornadoes and downbursts are a major cause of natural disturbance in forests of eastern North America, accounting for thousands of hectares of disturbed area annually. Wind disturbance shows substantial regional variation, decreasing from the mid-west to the east and from the south-east to New England. In terms of the relative importance among these types of storms, more forest damage results from tornadoes in the south-east and mid-west, while downbursts are the most important type of wind disturbance in the Great Lakes area. Downbursts vary widely in size, but large ones can damage thousands of hectares, while tornadoes are much smaller, seldom affecting more than several hundred hectares. Tornadoes cause the most severe wind disturbances. Site characteristics such as physiography, soil moisture, and soil depth; stand characteristics like density and canopy roughness; and tree characteristics such as size, species, rooting depth, and wood strength, are the factors most recognized as influencing damage patterns. The consequences of wind damage to forests, such as change in environmental conditions, density, size structure, species composition, and successional status, occur on both immediate (hours-to-days) and long-term (months-to-decades) time scales. Most wind disturbances result in the post-disturbance vegetation being comprised of surviving canopy trees, and varying amounts of sprouts, released understory stems, and new seedlings. Stand size structure is usually reduced, and successional status of a forest is often advanced. Diversity can be either increased or decreased, depending on the measure of abundance used to calculate diversity. Because tornadoes and downbursts are in part products of thermodynamic climatic circumstances, they may be affected by anticipated changes in climatic conditions as the 21st century progresses. However, the current understanding of tornado and downburst formation from supercell storms is very incomplete, and climate-change model predictions sufficiently coarse, that predictions of changes in frequency, size, intensity, or timing of these extreme events must be regarded as highly uncertain. Moreover, retrospective approaches that employ tree demography and dendrochronology require prohibitively large sample sizes to resolve details of the relationship between climate fluctuations and characteristics of these storms. To improve predictions of changes in the climatology of these storms, we need improved understanding of the genesis of tornadoes and downbursts within thunderstorms, and greater resolution in global climate models. To improve coping strategies, forest scientists can contribute by giving more attention to how various silvicultural actions influence stand and tree vulnerability. Finally, increased focus on the dynamics of forest recovery and regrowth may suggest management actions that can facilitate desired objectives after one of these unpredictable wind disturbances.

Catnip essential oil as a barrier to subterranean termites (Isoptera: Rhinotermitidae) in the laboratory.

The essential oil of catnip, Nepeta cataria (Lamiacae) was evaluated for behavioral effects on two populations of subterranean termite, Reticulitermes flavipes (Kollar) and R. virginicus (Banks) (Isoptera: Rhinotermitidae). The catnip essential oil contained approximately 36:64 E,Z-nepetalactone and Z,E-nepetalactone, respectively. The time to 50% dissipation (DT50) of the isomers in sand was dependent on dose, and ranged from 5.7 to 12.6 d for the E,Z-isomer and 7.7-18.6 d for the Z,E-isomer. For R. flavipes, the 24-h topical LD50 value was approximately 8200 microg/g termite. The 24-h fumigation LC50 value for R. flavipes was between 36 and 73 microg/ml air, and the 7-d fumigation LC50 value was between 14 and 36 microg/ml air. Exposure of R. virginicus to treated sand resulted in a 24-h LC50 value (95% F.L.) of 84 (67.6, 112) microg/cm2 and a 7-d LC50 value of 21.1 (16.4, 26.8) microg/cm2; for R. flavipes these values were 63.2 (53.7, 73.9) and 44.4 (34.6, 58.1) microg/cm2, respectively. Vertical tunneling through treated sand was eliminated at 500 ppm for R. virginicus and at 250 ppm for R. flavipes. Horizontal tunneling was stopped at 250 ppm for R. virginicus and reduced at doses above 250 ppm for R. flavipes. Although tunneling ceased in these tests, mortality was not high, indicating that the termites avoided the treated sand. Efficacy of catnip oil was equivalent to other monoterpenoids reported in the literature.

Inferring colonization history from analyses of spatial genetic structure within populations of Pinus strobus and Quercus rubra.

Many factors interact to determine genetic structure within populations including adult density, the mating system, colonization history, natural selection, and the mechanism and spatial patterns of gene dispersal. We examined spatial genetic structure within colonizing populations of Quercus rubra seedlings and Pinus strobus juveniles and adults in an aspen-white pine forest in northern Michigan, USA. A 20-year spatially explicit demographic study of the forest enables us to interpret the results in light of recent colonization of the site for both species. We assayed 217 Q. rubra seedlings and 171 P. strobus individuals at 11 polymorphic loci using nine allozyme systems. Plant genotypes and locations were used in an analysis of spatial genetic structure. Q. rubra and P. strobus showed similar observed levels of heterozygosity, but Q. rubra seedlings have less heterozygosity than expected. Q. rubra seedlings show spatial genetic clumping of individuals on a scale to 25 m and levels of genetic relatedness expected from the clumped dispersion of half-siblings. In contrast, P. strobus has low levels of genetic relatedness at the smallest distance class and positive spatial genetic structure at scales < 10 m within the plot. The low density of adult Q. rubra outside the study plot and limited, spatially clumped rodent dispersal of acorns is likely responsible for the observed pattern of spatial genetic structure and the observed heterozygote deficit (i.e. a Wahlund effect). We attribute weaker patterns observed in P. strobus to the longer dispersal distance of seeds and the historical overlap of seed shadows from adults outside of the plot coupled with the overlap of seed shadows from younger, more recently established reproductive adults. The study demonstrates the utility of long-term demographic data in interpreting mechanisms responsible for generating contemporary patterns of genetic structure within populations.

Osteochondritis dissecans of the humeral head of a cat.

A one-year-neutered male cat was presented for veterinary examination because of a left forlimb lameness. A painful left shoulder joint was found on examination and radiology of this joint revealed an erosive lesion of the humeral head and a detached flap of articular cartilage. The detached cartilage was surgically removed after which the lameness resolved. The lesion in this cat resembled osteochondritis dessicans of other species but whether the pathogenesis of the condition in this cat was 115 similar also was not determined.

A segmented polyurethane composite prosthetic anterior cruciate ligament in vivo study.

A segmented polyurethane prosthetic anterior cruciate ligament prototype has been developed and its in vivo integrity assessed in canine subjects. Prosthetic ligaments surgically implanted for 3, 4, 6, 8, 12, and 16 months were assessed clinically in living subjects, at time of autopsy, and microscopically postautopsy. It was found that the ligaments were adequate in strength to provide stability and last for periods up to 16 months. Notching of the ligaments was observed at two designated friction points.

Quality and biochemical effects of a IBL/IRS wheat-rye translocation in wheat.

Wheat (Triticum aestivum L.) breeders world-wide have used rye (Secale cereale L.) as a source of genes for agronomic improvement. The 1BL/1RS wheat-rye chromosomal translocation derived from the Russian cultivars 'Kavkaz' and 'Aurora' has been among the most common means of accessing useful rye genes. Unfortunately, deleterious wheat quality effects are often associated with the presence of 1RS. The identification of genetic backgrounds capable of alleviating the deleterious effects of 1RS is crucial for its continued exploitation. End-use quality parameters and flour protein composition, as measured by size-exclusion high-performance liquid chromatography (SE-HPLC) of 373 wheat lines, derived from seven 1BL/1RS breeding populations, were analyzed. In all populations, significant quality defects were detected in 1BL/1RS lines compared to non-1RS sister lines. The detrimental quality effects resulted from alteration of the ratio of flour protein composition, especially, decreased glutenin concentrations, and increased salt-water soluble protein concentrations. The end-use quality of 1BL/1RS lines, however, was highly dependent on genetic backgrounds. The potential exists for improvement in quality through crosses between 1RS lines with high glutenin, or low salt-water soluble protein concentrations, and non-1RS lines with strong dough properties.

Mechanisms of differential growth of heart ventricles in newborn pigs.

The left ventricular free wall (LVFW) grew approximately three times faster than the right ventricular free wall (RVFW) during the first 10 days of life in neonatal pigs. Faster growth was associated with proportional increases in total RNA and messenger RNA. These findings indicated that greater capacity for protein synthesis was a major factor in accelerated growth. Despite faster growth, heart content of ribosomal subunits was higher in piglets than in 60-day-old pigs or adult rats, suggesting a relatively slower rate of peptide chain initiation than elongation. When hearts from 5-day-old pigs were perfused in vitro, protein synthesis was more rapid in the LVFW than in the RVFW. In the absence of added insulin, the higher rate was due to both greater efficiency and greater capacity for protein synthesis. In the presence of the hormone, greater capacity was responsible for the increased rate of protein synthesis in the LVFW as compared with the RVFW.

Accelerated ribosome formation and growth in neonatal pig hearts.

Rapid growth (5 mg dry heart/h) of the left ventricular free wall (LVFW) in the newborn pig heart accompanied by lack of growth of the right ventricular free wall (RVFW) represents a unique natural model of cardiac enlargement that is free of pathophysiological influences. By 3 days of life, LVFW was 71% larger than at 4 h of age. Rates of protein synthesis were measured during perfusion of isolated pig hearts with bicarbonate buffer containing glucose, lactate, insulin, and plasma concentrations of amino acids of an aortic pressure of 60 mmHg. In hearts from pigs that were 18 h of age, rates of protein synthesis were the same in RVFW and LVFW, but in 2-day-old pigs the rate was 52% greater in LVFW than RVFW. During the first 3 days of life, RNA content (mg/g) increased 3.4-fold faster in LVFW than RVFW. When RNA content was expressed per total heart portion, the increase was 7.9-fold greater. Because approximately 85% of total RNA is rRNA, these values indicated much more rapid formation of ribosomes in the LVFW than RVFW. When ribosome formation was measured in vitro in hearts from 48-h-old pigs, rates of formation were 39% greater in LVFW than RVFW, and at 18 h of age, ribosome formation was 40% faster in LVFW than RVFW. These findings indicated that formation of new ribosome preceded accelerated synthesis of total heart proteins. These findings indicated that rapid growth of LVFW compared with no growth of RVFW was associated with a 67% faster rate of ribosome formation and a 32% greater rate of protein synthesis.

Direct effects of myocardial depressant drugs on coronary vascular tone: anesthetic vasodilation by halothane and isoflurane.

Because certain vasoactive drugs also possess negative myocardial inotropic properties, it is difficult to determine their direct pharmacological actions on coronary resistance vessels in situ. Thus, a drug's myocardial effects may induce indirect physiological changes in coronary vascular tone that confound measuring its direct action. To separate the direct from indirect drug actions on vascular tone, the authors describe an experimental system utilizing the isolated perfused rat heart arrested with tetrodotoxin. The direct effects of the volatile anesthetics halothane and isoflurane on coronary vascular tone were examined in this preparation, using the concept of minimum alveolar concentration as the measure of potency. Both anesthetics demonstrated a dose-dependent direct coronary vasodilation that was reversible, with the median effective dose being 1.31 +/- 0.08 (mean +/- S.E.) for halothane, and 1.53 +/- 0.12 for isoflurane (P = 0.06; units of measure are the fraction of minimum alveolar concentration for each anesthetic). Further studies indicated that maximal vasodilation by adenosine was diminished after 90 min of perfusion, independent of anesthetic administration. Myocardial oxygen consumption was decreased significantly from the beating state by arrest, but neither anesthetic nor adenosine affected myocardial oxygen consumption further. These data indicate that halothane and isoflurane are equipotent for inducing direct dilation of coronary resistance vessels in the isolated perfused arrested rat heart.

Differential accumulation of a 24-kd dehydrin protein in wheat seedlings correlates with drought stress tolerance at grain filling.

The Pacific Northwest (PNW), an important region for wheat production in the USA, is often subject to water deficits during sowing and grain filling. These deficits reduce the quality and yield of the crop. As a consequence, an important objective of breeding programs in the region is improving the genetic adaptation of wheat cultivars to drought stress. One response to dehydrative stresses is the accumulation of proteins called dehydrins, which are believed to protect membranes and macromolecules against denaturation. We characterized dehydrin accumulation in seedlings during drought stress and its correlation with stress tolerance during grain filling in seven wheat cultivars, 'Connie', 'Gene', 'TAM105', 'Rod', 'Hiller', 'Rhode', and 'Stephens'. A 24-kd dehydrin accumulated in seedlings under stress, but not in irrigated control plants. Connie, TAM105, and Gene started to accumulate dehydrins at the fourth day of stress, while the other cultivars showed dehydrins after twelve days of stress. This differential accumulation in seedlings was associated with stress tolerance at grain filling, characterized by a lower reduction in yield and in the rate of decrease in leaf water potential per day of stress. Connie, TAM105, Gene and Rod where the most tolerant cultivars. The results indicate that expression of this 24-kd dehydrin might serve as a rapid and non-destructive screening technique at the seedling stage. Even though the results are promising, selection experiments using a population segregating for stress tolerance are needed to test more conclusively whether this dehydrin can serve as a genetic marker for cultivars with tolerance to drought stress.