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Cerebral haemodynamic response to neural stimulation has been extensively investigated in animal and clinical studies, in both adult and paediatric populations, but little is known about cerebral haemodynamic functional response in the fetal brain. The present study describes the cerebral haemodynamic response measured by near-infrared spectroscopy to somatosensory stimulation in fetal sheep. The cerebral haemodynamic response in the fetal sheep brain changes from a positive (increase in oxyhaemoglobin (oxyHb)) response pattern to a negative or biphasic response pattern when the duration of somatosensory stimulation is increased, probably due to cerebral vasoconstriction with prolonged stimulations. In contrast to adult studies, we have found that changes in fetal cerebral blood flow and oxyHb are positively increased in response to somatosensory stimulation during hypercapnia. We propose this is related to reduced vascular resistance and recruitment of cerebral vasculature in the fetal brain during hypercapnia.Functional hyperaemia induced by a localised increase in neuronal activity has been suggested to occur in the fetal brain owing to a positive blood oxygen level-dependent (BOLD) signal recorded by functional magnetic resonance imaging following acoustic stimulation. To study the effect of somatosensory input on local cerebral perfusion we used near-infrared spectroscopy (NIRS) in anaesthetised, partially exteriorised fetal sheep where the median nerve was stimulated with trains of pulses (2 ms, 3.3 Hz) for durations of 1.8, 4.8 and 7.8 s. Signal averaging of cerebral NIRS responses to 20 stimulus trains repeated every 60 s revealed that a short duration of stimulation (1.8 s) increased oxyhaemoglobin in the contralateral cortex consistent with a positive functional response, whereas longer durations of stimulation (4.8, 7.8 s) produced more variable oxyhaemoglobin responses including positive, negative and biphasic patterns of change. Mean arterial blood pressure and cerebral perfusion as monitored by laser Doppler flowmetry always showed small, but coincident increases following median nerve stimulation regardless of the type of response detected by the NIRS in the contralateral cortex. Hypercapnia significantly increased the baseline total haemoglobin and deoxyhaemoglobin, and in 7 of 8 fetal sheep positively increased the changes in contralateral total haemoglobin and oxyhaemoglobin in response to the 7.8 s stimulus train, compared to the response recorded during normocapnia. These results show that activity-driven changes in cerebral perfusion and oxygen delivery are present in the fetal brain, and persist even during periods of hypercapnia-induced cerebral vasodilatation.

Russian wildrye [Psathyrostachys juncea Nevski] is potentially useful as a cool-season forage grass for the southern Great Plains. Our objective was to determine the effect of acidic and limed soils on seedling growth of tetraploid and diploid Russian wildrye germplasm. Seedlings of Mandan R1983 and Tetra-1 (tetraploids), as well as 'Bozoisky Select' and 'Mankota' (diploids), were grown in limed and nonlimed acidic sand, sandy loam, and silt loam soils in the greenhouse at Ardmore, OK. Seedlings were harvested following approximately 60 d of growth in soil. Root-bound Al was extracted with a solution of 0.5 M citric add. Regardless of soil type, seedling shoots grew significantly (P < 0.05) larger because of lime application, averaging 13.1 cm taller and 100% heavier for limed versus nonlimed acidic soils. Tiller number, root length, and root weight also increased with lime application, though not as consistently. Root-bound Al did not differ between tetraploids and diploids. In most cases, tetraploids and diploids had an equally favorable response to liming, indicating that Russian wildrye seedlings are susceptible to soil acidity regardless of ploidy level. Because of consistency of response and ease of measurement, seedling shoot weight should be useful for screening Russian wildrye germplasm for possible tolerance to soil acidity. Russian wildrye cultivars with improved seedling tolerance to acidic soils, which occur extensively in the southern Great Plains, might well be needed.

AC Hartland, a hard red spring feed wheat (Triticum aestivum L. em. Thell.) is adapted to Eastern Canada. It expressed high grain yield, lodging resistance, and a high level of resistance to powdery mildew. Key words: Triticum aestivum, red spring wheat, yield, cultivar description

GHB produced a concentration-dependent depression of evoked synaptic field potentials (EFPs) recorded extracellularly in the CA1 region of the in vitro rat hippocampal slice. The concentration/response function revealed a threshold near 1 mM, with IC50 of 10.85 mM and a Hill coefficient of 1.29. The gamma-aminobutyric acid B-receptor (GABA-B) agonist baclofen also depressed the EFP, but even maximally effective concentrations of the GABA-B antagonist 2-hydroxy-saclofen (800 microM) could not completely block the GHB-induced EFP depression. Nor was GHB-induced EFP depression blocked by the GHB receptor "antagonist" NCS-382, which does not displace GABA-B receptor ligands. However, NCS-382 produced a concentration-dependent increase in EFP slope. The threshold concentration was about 100 microM but the maximally effective concentration, and thus the IC50, could not be determined in the perfusion slice system. NCS-382 may be an inverse agonist at hippocampal GHB receptors, or else endogenous hippocampal GHB receptor ligands medicate a tonic inhibition in CA1. At concentrations sufficient to induce EFP depression GHB did not alter pH. Although isosmotic sucrose did depress CA1 EFPs it was essentially ineffective at the IC50 for GHB. Gamma-butyrolactone, a prodrug of GHB, was only 1/20th as effective as GHB. This is consistent with previous data suggesting that GBL is freely permeable (does not substantially disturb tonicity) and that brain has very little capacity to either enzymatically convert the lactone to GHB or respond to the lactone itself.

Accurate predictions of forage quality of winter wheat (Triticum aestivum L.) during spring would allow targeting of harvests or grazings to desired levels of nutritive composition to meet specific animal requirements. The objectives of this study were to compare number of days since 15 February (DAYS) and growing degree days (GDD, base 4.4 °C) as predictors of Feekes and Zadoks growth stages, and to compare DAYS, GDD, Feekes, and Zadoks growth stages as predictors of forage yield and quality. The 2-yr study on a Captina silt loam (fine, mixed, mesic, Typic Fragiudult) at the University of Arkansas Main Experiment Station, Fayetteville, AR, involved four cultivars of soft red winter wheat. Plots were harvested at six growth stages: beginning of pseudostem elongation, second node detectable, flag leaf collar just visible, boot swollen, inflorescence completely emerged, and soft dough. Feekes and Zadoks growth stage scales were regressed on DAYS and GDD. Forage yield, percentage lamina (ratio of leaf lamina to whole-plant dry weight), and nutritive concentrations were regressed on Feekes, Zadoks, DAYS, and GDD. Lower root error mean squares were generally obtained with GDD than DAYS for predicting growth stages. Zadoks scale and DAYS were generally the best predictors of forage yield, whereas Feekes scale and DAYS were the best predictors of percentage lamina and crude protein. Zadoks and GDD were the best predictors of neutral detergent fiber and in vitro dry matter digestibility. The Zadoks scale and GDD would be useful parameters in wheat growth models designed to target harvests to desired levels of forage quality. Published with approval of the Director of the Arkansas Agric. Exp. Stn

In fetal lambs after 115 days gestation breathing movements become episodic in association with electrocortical differentiation into predominantly high voltage slow or low voltage rapid activity, the latter characteristic of rapid eye movement sleep. Section of the brainstem at or above the colliculi dissociates fetal breathing from electrocortical activity. It is included that breathing is inhibited, towards the end of gestation, by a supracollicular mechanism during high voltage activity. After brainstem transection at the colliculi hypoxia no longer causes an arrest of fetal breathing, which often becomes more vigorous. The arrest of breathing in normal fetuses subjected to mild hypoxia is also attributed to a supracollicular mechanism. The pattern of fetal skeletal movements and of the spinal segmental reflexes is related to electrocortical activity near term; both are suppressed by hypoxia. The hypothesis is discussed of a central control centre, excited directly or indirectly by hypoxia, which inhibits fetal movements including breathing. Its possible location is considered.

This paper describes the RTGrid distributed simulation framework for conformal radiotherapy. We introduce novel approaches through which several distributed computing technologies are made accessible to Monte Carlo simulations for radiotherapy dose calculations. Currently, radiotherapy treatment planning is typically performed on PCs and workstations which lack the computational power to run Monte Carlo simulations quickly enough to be useful to clinicians. Therefore, although Monte Carlo simulation techniques offer highly accurate doses, they are seldom chosen for clinical deployment. The RTGrid project is investigating both the capability and capacity modes of exploiting grid computing for radiotherapy treatment planning using Monte Carlo simulations.

We investigated the effect of increasing the synaptic concentration of catecholamines released from central pathways on breathing movements and electrocortical (ECoG) activity in fetal sheep in utero. In 11 trials (9 fetuses) intravenous infusion of the noradrenergic uptake inhibitor desipramine (DMI) resulted in an initial increase in the incidence of breathing movements from 47.8 +/- 2.2%/h to a maximum of 77.9 +/- 5.5%/h (P less than 0.05) followed by a subsequent decrease to 18.8 +/- 2.7%/h (P less than 0.05), which was associated with a decrease in the incidence of low-voltage ECoG activity. Mean breath amplitude also increased after DMI infusion from 5.8 +/- 0.2 mmHg to a peak of 8.9 +/- 0.9 mmHg (P less than 0.05). In five fetuses, intravenous injection of the alpha 1-receptor antagonist prazosin 30 min after the start of the DMI infusion blocked the increase of breath amplitude observed when DMI was given alone. Intracisternal infusion of 6-hydroxydopamine (6-OHDA, which causes an initial displacement of transmitter stores followed by a neurotoxic action) in six fetuses caused an increase in mean breath amplitude from 6.6 +/- 0.3 mmHg (control) to 22.3 +/- 5.5 mmHg (P less than 0.05) and a prolonged episode of breathing movements (168.5 +/- 47.2 min). The incidence of low-voltage ECoG activity was also increased significantly. A second infusion of 6-OHDA, 2 days after the first, had no effect on breathing movements or ECoG activities. The two treatments with 6-OHDA also resulted in a significant reduction in the response to intravenous infusion of DMI, indicating that endogenous release of norepinephrine had been reduced by the neurotoxin. These results suggest that 1) there is normally some tonic release of norepinephrine from central pathways, but this release is insufficient to stimulate sustained fetal breathing, and 2) accumulation in the synaptic cleft of catecholamines from central neurons is able to stimulate fetal breathing and promote low-voltage ECoG activity. Possible mechanisms that normally limit the activity of central catecholamine pathways before birth are discussed.

An enhancer element in the 5' flanking region of the human apolipoprotein E gene, known as upstream regulatory element 1 (URE1), has previously been implicated in the expression of this gene. The URE1 element, which spans nucleotides -193 to -124 of the 5'-flanking region of the human apolipoprotein E gene, contains two sequences that bind to nuclear proteins, as determined by the DNase I footprinting assay. In the present study of URE1, we have characterized these sequences further. Deletion of one of the footprint sequences, at nucleotides -161 to -141, reduced URE1 enhancer activity substantially. A 30-base pair oligonucleotide that included this protein-binding sequence was able, by itself, to act as an enhancer. This sequence, termed the positive element for transcription (PET), was demonstrated by gel retention analysis to bind at least two protein factors, one of which is the transcription factor Sp1. Sp1 appeared to be the only protein required for the enhancer activity of PET to be manifested. In vitro transcription assays showed that the PET sequence was necessary for efficient transcription directed by the apoE promoter and that the PET sequence was the dominant regulatory element in the apoE promoter. Gel filtration chromatography and PET oligonucleotide-affinity chromatography were used to isolate a second PET-binding factor, a Mr = 55,000 protein, from HeLa cell nuclear extracts. It appeared to compete with Sp1 for a common binding site in the PET sequence, but it was not required for enhancer activity. The second footprint sequence in URE1, at nucleotides -184 to -173, also bound Sp1, but it was not required for enhancer activity. A third Sp1-binding region was located at a proximal GC box element (nucleotides -54 to -45). This region had no enhancer activity, but it was required for maximum transcriptional activity of the apoE promoter. Thus, the regulation of apoE gene expression is influenced by different protein-binding sequences, with transcription factor Sp1 playing major roles in both basal promoter activity and enhancer activity.

Our objectives were to compare wheat and wheat-ryegrass mixtures for patterns of DM accumulation and forage quality changes with maturity. Two genotypes of soft red winter wheat (‘Magnum' and the hybrid ‘HW 3015') were grown alone or in mixture with ‘Marshall' annual ryegrass. Plots were harvested at six wheat growth stages from beginning of pseudostem elongation to soft dough. Handclipped samples were separated into species and leaf and stem (including inflorescence) components, and the components were analyzed for NDF and in vitro DM disappearance. Annual ryegrass in mixture with wheat did not enhance the forage yield over wheat alone; however, the later maturity of ryegrass in relation to wheat resulted in a slower decline in total mixture leaf proportion with advancing maturity than in wheat alone. Enhanced leafiness did not, however, augment total mixture in vitro DM disappearance over that of wheat alone because of the low in vitro DM disappearance of ryegrass stems. If wheat is to be grown for harvest at the soft dough stage for forage, it should not be grown with annual ryegrass, because the latter dilutes the high quality, wheat grain portion with low quality ryegrass stems.

Atmospheric tritium monitoring involves the collection of tritiated water vapor by collecting atmospheric moisture from air that is drawn through a bed of desiccant material. This study is a comparison between molecular sieve and silica gel adsorbent media used for atmospheric moisture sampling conducted in the semi-arid climate of the Idaho National Engineering and Environmental Laboratory. Water vapor was collected simultaneously using two columns containing different desiccant materials (one column containing molecular sieve and the other containing silica gel). Data collected during air sampling periods were compared with meteorological data collected, and atmospheric moisture collection efficiencies were determined. Breakthrough of atmospheric moisture past the desiccant material was suspected with both media at elevated temperatures indicating that smaller sample volumes, lower volumetric flow rates, or longer adsorbent columns should be used during summer when ambient temperatures are elevated.

In 1999, the State of Idaho INEEL Oversight Program performed a field test to determine if electret ion chambers could be used as a replacement to soil sampling in field survey releases at a remediated radioactively contaminated site. This study compared exposure rates measured using electret ion chambers with gamma spectroscopic analysis results of soil samples collected at the remediated site. Exposure rate measurements were made in 1999 using electret ion chambers at the same locations that INEEL Oversight Program sampled soil in 1998 following MARSSIM protocol. The waste site was divided into nine survey units based upon site history including previous site surveys and physical boundaries. Exposure rate measurements at the remediation site compared well with exposure rate measurements made at reference background locations used for routine environmental monitoring by the State of Idaho indicating that the remedial action met cleanup criteria. A poor correlation between exposure rate measurements and 137 Cs concentrations and other discrepancies were observed during this study with respect to measurements made during the 1998 final site survey.

The effects of 2-(4-Morpholinyl)-8-phenyl-4H-1-benzopyran-4-one (LY294002), an inhibitor of mammalian phosphatidylinositol 3-OH kinase, was tested on an insulin signaling-like pathway in the nematode Caenorhabditis elegans. Populations of C. elegans were treated with LY294002 at different stages of the life cycle, and its effects on development, thermotolerance and longevity were assessed. At concentrations of 160 microM and above, LY294002 significantly induced both dauer formation and thermotolerance. Treatment of adult worms also resulted in a small, but significant, increase in life span. The results presented are consistent with the view that a neuroendocrine signaling pathway functions in adult worms to determine stress resistance and longevity.

Chronic ethanol treatment (CET) for 28 weeks significantly increases electrically-stimulated 3H-GABA release from hippocampal slices. This increase in GABA release may be one of the mechanisms by which CET decreases the magnitude of long-term potentiation (LTP) in the hippocampus. The present study examined whether CET increases GABA release via an alteration in heterologous presynaptic cholinergic regulation.Animals were treated with ethanol or sucrose diet for 28 weeks followed by either no withdrawal or a 48-hr withdrawal period. The electrically-stimulated 3H-GABA release from preloaded superfused hippocampal slices of naive and CET rats was measured.Carbachol increased 3H-GABA release in a concentration-dependent manner, and atropine modulated 3H-GABA release in a biphasic concentration-dependent manner. Atropine (10 microM) significantly blocked the effects of carbachol. Oxotremorine, a selective muscarinic receptor agonist, also increased 3H-GABA release. Mecamylamine, a selective nicotinic antagonist, did not modulate 3H-GABA release and did not block the effects of carbachol. The effects of these agents were also tested in rats 0 or 48 hrs after withdrawal from CET. The biphasic effects of atropine were decreased, whereas the facilitating effects of carbachol were significantly increased. There were no changes in the effects of these agents on 3H-acetylcholine release from hippocampal slices of CET rats compared to sucrose-treated rats.These results suggest that presynaptic muscarinic receptors facilitate GABA release, whereas nicotinic receptors do not play a significant role in modulating GABA release in hippocampus. CET selectively alters presynaptic muscarinic regulation of GABA release in hippocampus and may help us to further understand the mechanism underlying the disruption of LTP by CET.

Studies of aging in the nematode Caenorhabditis elegans have revealed a relationship between stress resistance and the rate of aging: Mutations which extend mean and maximum life-span also confer resistance to thermal stress. We review the molecular genetics of aging in C. elegans and introduce methods for obtaining novel mutants which display altered aging rates. We present the use of the "surrogate" phenotype of thermotolerance to develop a selection for novel mutations which slow aging.

The neurotoxic effect of acute ethanol treatment (AET) may lead to an alteration in the regulation of calcium (Ca2+) homeostasis in hippocampal neurons. Ca2+ homeostasis could be affected by AET when neurons are at rest or after depolarizing activity during synaptic transmission. It has been shown that nerve growth factor (NGF) can ameloriate some types of neurotoxicity by stabilizing Ca2+ homeostasis. Previously, we observed that ethanol (EtOH) changed unstimulated (basal) and potassium (K+)-stimulated intracellular calcium ([Ca2+]i) in embryonic septohippocampal neurons (Webb et al., Brain Res. 729:176-189, 1996). The purpose of the present study is to determine the effects of NGF and EtOH on neuronal Ca2+ homeostasis in cultured embryonic hippocampal neurons. The hypotheses tested were the following: EtOH alters Ca2+ homeostasis in hippocampal neurons; NGF modulates Ca2+ homeostasis in hippocampal neurons; and NGF treatment alters the effect of EtOH on [Ca2+]i in hippocampal neurons. Our results indicated that hippocampal neuronal cultures treated with EtOH had lower basal [Ca2+]i than untreated neurons. EtOH decreased K+-stimulated (30 mM KCI) changes in [Ca2+]i in a dose-dependent manner. During K+ stimulation, 20 ng/ml of NGF slowed and reduced the increase in [Ca2+]i. Hippocampal neurons treated with NGF increased or did not change basal [Ca2+]i and did not change or increase K+-stimulated [Ca2+]i in response to EtOH. These responses were dose-related and indicated that NGF could alter the response of hippocampal neurons to EtOH. In conclusion, AET results in the alteration of Ca2+ homeostasis in unstimulated and depolarized cultured embryonic hippocampal neurons. NGF and EtOH independently and collectively affected the regulation of Ca2+ homeostasis in this neuronal population. Changes in [Ca2+]i can disrupt normal cellular function and contribute to cell death. Therefore, alteration of Ca2+ homeostasis may be an underlying mechanism involved in EtOH toxicity. NGF may ameliorate the toxic effects of EtOH by regulating Ca2+ homeostasis.

The amino acid L-glutamate is a major excitatory neurotransmitter that is involved in many CNS functions, including learning, memory, long-term potentiation, and synaptic plasticity. Acute exposures to ethanol (50 to 200 mM) have been shown to inhibit NMDA receptor responses, whereas chronic exposure to ethanol leads to adaptive supersensitivity thought to be involved in ethanol dependence and tolerance. To investigate the effects of chronic ethanol exposure on glutamate receptor density, we examined the binding of both NMDA and non-NMDA ligands in rat brain after several chronic ethanol treatment protocols using a number of different rat strains. No increases in the binding of [3H]MK-801, [3H]CGP 39653, or the polyamine specific competitive antagonist, [3H]ifenprodil, were seen after two well-used chronic ethanol treatments. These included the 2-week liquid diet developed by Frye et al. (J. Pharmacol. Exp. Ther. 216:306-314, 1981) and the 4-day binge treatment developed by Majchrowicz (Psychopharmacologia 43:245-254, 1975). However, small increases in the binding of both the NMDA noncompetitive antagonist [3H]MK-801, as well as the competitive NMDA antagonist [3H]CGP 39653, were seen in select frontal brain regions after 3 weeks of the Walker-Freund chronic ethanol liquid diet. When this chronic liquid diet treatment was extended to a period of 6 weeks, these increases in receptor binding were diminished to nonsignificant levels. The binding of the non-NMDA ligands [3H]AMPA and [3H]kainate were not significantly affected by either length of Walker-Freund liquid diet exposure. When rats were treated chronically with ethanol for 30 days using the paradigm developed by Tsukamoto et al. (Hepatology 5:224-232, 1985), small, but significant, increases in the binding of [3H]MK-801 were seen in the CA1 and dentate gyrus regions of the hippocampus. These studies indicate that robust increases in NMDA receptor binding do not occur with several chronic ethanol treatment protocols, and suggests that NMDA receptor supersensitivity during the development of tolerance and dependence to ethanol may not simply be due to changes in the density of NMDA receptors, but may involve other mechanisms.

Chronic ethanol treatment (CET), sufficient for decreasing long-term potentiation (LTP) in rats, also enhances 3H-GABA release from hippocampal slices in these same animals. The mechanism for an increase in GABA release may involve changes in presynaptic receptors. Therefore, we characterized presynaptic autoreceptor modulation of 3H-GABA release in hippocampal slices from control and CET rats. The effects of a GABAB receptor agonist (baclofen) and antagonist [2-hydroxy (OH)-saclofen] were tested for their ability to modulate electrically stimulated 3H-GABA release from superfused hippocampal slices. Baclofen decreased stimulated release in a dose-dependent manner and 2-OH-saclofen increased release consistent with the existence of presynaptic GABAB autoreceptors in hippocampus. The GABAA antagonist bicuculline did not significantly modulate basal or stimulated release. When the effects of baclofen and 2-OH-saclofen were measured in animals 48 hr after withdrawal from CET, presynaptic modulation of release by baclofen and 2-OH-saclofen was decreased. In addition, we examined the density of 3H-baclofen and 3H-bicuculline binding in the hippocampal formation using quantitative autoradiographic techniques. We found that the density of 3H-baclofen binding sites was not affected by CET, whereas the density of 3H-bicuculline binding sites was increased by 28% in ethanol-treated rats. These data may explain how CET increases presynaptic regulation of GABA release from hippocampus that may contribute to the decrease in LTP seen in rats after CET.

Exposure of human fetuses to ethanol often results in the fetal alcohol syndrome. Animal models of fetal alcohol syndrome have been developed and used to examine the consequences of prenatal ethanol exposure on the central nervous system. The objective of this study was to determine the long-term effects of prenatal ethanol exposure on parvalbumin-expressing (PA+) GABAergic neurons of the rat medial septum. Pregnant Long-Evans rats were maintained on 1 of 3 diets from gestational day 0 to 21: an ethanol-containing liquid diet in which ethanol accounted for 35% of the total calories, a similar diet with the isocaloric substitution of sucrose for ethanol, or a lab chow control diet. Offspring were killed on postnatal day 60, and their brains were prepared for parvalbumin immunocytochemistry. Female rats exposed to the ethanol-containing diet during gestation had 42% fewer PA+ neurons in the medial septum and reduced PA+ cell density when compared with female rats exposed to the sucrose diet. Ethanol females also had fewer PA+ neurons per unit volume than sucrose females. Male rats exposed to ethanol did not display a similar reduction in PA+ neurons or density. No effect of prenatal diet was found on the area or volume of the medial septum, nor were cell diameters affected. As such, prenatal exposure to ethanol seems to reduce permanently the number of PA+ neurons in the female rat medical septum without affecting area, volume, or neuronal size. Functional implications and possible relations to the fetal alcohol syndrome are discussed.

Ethanol and nerve growth factor (NGF) affect the survival of septohippocampal (SH) neurons. The effect of ethanol and NGF on calcium (Ca2+) homeostasis in these neurons was investigated in this study. Changes in intracellular-free Ca2+ concentration ([Ca2+]i) were measured using indo-1 in cultured embryonic (E21) SH neurons before stimulation (basal) and during stimulation with 30 mM potassium cloride (KCl+). SH neurons were treated with 0, 100, 200, 400, or 800 mg% ethanol with NGF (+NGF) or without NGF (-NGF). NGF treatment decreased, while ethanol did not affect basal [Ca2+]i. The combination of ethanol and NGF treatment led to increases in basal [Ca2+]i. While [Ca2+]i was lower during stimulation with KCl+ following ethanol or NGF treatment, ethanol and NGF treatment together led to significantly greater increases or decreases in [Ca2+]i compared to similarly treated NGF neurons. Responses of SH neurons were compared to those of medial septal (MS) neurons. Changes in [Ca2+]i during treatment with ethanol and/or NGF were reduced in SH neurons compared with MS neurons. We conclude that changes in Ca2+ homeostasis can occur in SH neurons in the presence of ethanol and/or NGF. The changes following ethanol treatment are enhanced by NGF. By altering Ca2+ homeostasis, NGF may enhance the survival of SH neurons during ethanol-induced neurotoxicity.

This study investigated the influence of ethanol exposure throughout gestation on cholinergic development within the rat striatal region. Pregnant Long-Evans rats were maintained on three diets throughout gestation: A liquid diet in which ethanol accounted for 35-39% of the total calories, a similar diet with the isocaloric substitution of sucrose for ethanol, and a lab chow control diet. At postnatal days 14 and 60 (P14 and P60), the striatal regions of the offspring were analyzed for the number of cholinergic neurons, via choline acetyltransferase (ChAT) immunostaining. The area of the striatum was also measured in these animals. At P14, P21, and P60, ChAT activity was assessed in the same region. These analyses revealed a significant increase in the number of cholinergic striatal neurons at P14 in the animals which had been exposed prenatally to ethanol. This increase was transient, however, with equal numbers of ChAT-positive cells found in all three groups by adulthood (P60). The brain weights of the ethanol-exposed animals were significantly reduced at P14 and P21, but were comparable to controls by P60. There were no significant differences in the striatal area or the overall volume of the region assessed, however, at either P14 or P60. Although there were some increases in ChAT activity across the ages viewed (most notably between P14 and P21), there were no effects of diet on ChAT activity at any age assessed. It is proposed that the increased numbers of cholinergic neurons could be a function of errors in migration, enhanced neurogenesis, diminished cell death, alterations in gene expression, or increased cell survival as a result of alterations in neurotrophic factor production or availability.

Patients with chronic alcoholism and/or Alzheimer's disease suffer from degenerative changes in the cerebral cortex and hippocampus. To investigate possible changes in IGF-1 receptor binding sites in brain tissue of patients with these pathological conditions, the binding of [125I]-IGF-1 was determined in tissues obtained from control, Alzheimer's and/or patients with a history of alcoholism. The four experimental groups examined consisted of patients from similar age groups. Specific binding of [125I]-IGF-1 to cerebral cortical membranes from Alzheimer's patients had significantly more binding sites than age-matched controls, alcoholic patients and alcoholic patients with Alzheimer's disease. Regression analyses indicated that there were no significant differences in [125I]-IGF-1 binding in cerebral cortex with regard to age of patients (1.1% of total variance with a range of 52 to 92 years). Likewise, the time interval between death and autopsy contributed only 1.4% to the total variance in IGF-1 binding. No statistical differences in [125I]-IGF-1 binding were noted in hippocampal tissue from the various patient groups. Thus, human IGF-1 binding sites in cerebral cortex and hippocampus appear to be relatively stable for a number of variables. The increase in cerebral cortical [125I]-IGF-1 binding sites could be due to upregulation of IGF-1 receptors resulting from a decrease in IGF-1 levels in Alzheimer's patients.

An enhancer element in the 5' flanking region of the human apolipoprotein E gene, known as upstream regulatory element 1 (URE1), has previously been implicated in the expression of this gene. The URE1 element, which spans nucleotides -193 to -124 of the 5'-flanking region of the human apolipoprotein E gene, contains two sequences that bind to nuclear proteins, as determined by the DNase I footprinting assay. In the present study of URE1, we have characterized these sequences further. Deletion of one of the footprint sequences, at nucleotides -161 to -141, reduced URE1 enhancer activity substantially. A 30-base pair oligonucleotide that included this protein-binding sequence was able, by itself, to act as an enhancer. This sequence, termed the positive element for transcription (PET), was demonstrated by gel retention analysis to bind at least two protein factors, one of which is the transcription factor Sp1. Sp1 appeared to be the only protein required for the enhancer activity of PET to be manifested. In vitro transcription assays showed that the PET sequence was necessary for efficient transcription directed by the apoE promoter and that the PET sequence was the dominant regulatory element in the apoE promoter. Gel filtration chromatography and PET oligonucleotide-affinity chromatography were used to isolate a second PET-binding factor, a Mr = 55,000 protein, from HeLa cell nuclear extracts. It appeared to compete with Sp1 for a common binding site in the PET sequence, but it was not required for enhancer activity. The second footprint sequence in URE1, at nucleotides -184 to -173, also bound Sp1, but it was not required for enhancer activity. A third Sp1-binding region was located at a proximal GC box element (nucleotides -54 to -45). This region had no enhancer activity, but it was required for maximum transcriptional activity of the apoE promoter. Thus, the regulation of apoE gene expression is influenced by different protein-binding sequences, with transcription factor Sp1 playing major roles in both basal promoter activity and enhancer activity.

Exposing pregnant sheep to an ambient temperature of 43 +/- 1 degree C for 8 h was associated with a 1-1.5 degrees C increase of maternal and fetal core temperatures, and a 11-fold and 3-5 fold increase in maternal and fetal plasma prolactin concentrations respectively. Hyperthermia did not change maternal or fetal plasma cortisol concentrations. We conclude that maternal and fetal hyperprolactinaemia may occur in late pregnancy during hyperthermic conditions and that the increase in fetal plasma prolactin is due to either increased secretion or decreased metabolic clearance of prolactin in the feto-placental compartment.

The antigens of Rickettsia sibirica, Rickettsia rickettsii, and Rickettsia conorii were examined by Western immunoblots and the standard immunofluorescent serotyping assay with mouse anti-Rickettsia sibirica serum that is used for determining the species identification of spotted fever group rickettsiae. Serum was employed prior to absorption and after absorption with purified native or heated Rickettsia sibirica. The unabsorbed antiserum, the antiserum absorbed with heated Rickettsia sibirica and the antibodies eluted from native Rickettsia sibirica recognized two antigenic polypeptides of Rickettsia sibirica (130 and 118 kDa), Rickettsia rickettsii (151 and 133 kDa), and Rickettsia conorii (136 and 113 kDa), respectively when examined in native state, not denatured by heat. The antiserum absorbed with native Rickettsia sibirica reacted most strongly with one polypeptide of Rickettsia sibirica (118 kDa), Rickettsia rickettsii (133 kDa), and Rickettsia conorii (136 kDa); at the endpoint of the immunofluorescence assay there was minimal reactivity with the 130 kDa polypeptide by immunoblotting. Both Western immunoblots and immunofluorescence assay showed that the antiserum absorbed with native Rickettsia sibirica reacted with homologous and heterologous antigens at a much lower titer than did the antiserum that was not absorbed. However, the titers of reaction with Rickettsia sibirica, Rickettsia rickettsii, or Rickettsia conorii were not diminished by absorption of the native antiserum with heated Rickettsia sibirica. The antibody eluted from native Rickettsia sibirica reacted by immunofluorescence with all the rickettsiae at a higher dilution than the antibody eluted from heated Rickettsia sibirica.(ABSTRACT TRUNCATED AT 250 WORDS)

AC Norboro is a spring feed wheat (Triticum aestivum L. em. Thell.) with high grain yield and early maturity. It is moderately resistant to powdery mildew, and susceptible to leaf blotch. AC Norboro is slightly more susceptible to fusarium head blight than AC Wilmot, Belvedere, and AC Baltic. AC Norboro was developed by Agriculture And Agri-Food Canada. Key words: Triticum aestivum, wheat (spring), cultivar description

AC Wilmot is a spring feed wheat (Triticum aestivum L. em Thell.) with more grain yield than the check cultivars in Atlantic Canada. It is moderately resistant to powdery mildew. The reaction of AC Wilmot to leaf and glume blotch is similar to the check cultivars. AC Wilmot is slightly more susceptible to fusarium head blight than the check cultivars. AC Wilmot is suitable for production in Atlantic Canada. Key words: Triticum aestivum, wheat (spring), cultivar description

1. Movement of the chest wall and abdomen during episodes of breathing has been measured by an ultrasound technique in ten fetal lambs. 2. The fetal thoracic and abdominal walls move inwards and outwards respectively during inspiration. The position where this transition occurs is variable. 3. Movement of the lateral thoracic walls is reduced or reversed during breathing stimulated by hypercapnia while inward dorso-ventral movement increases. 4. Deep inspiratory efforts were associated with large inward then outward movements of the lateral and large inward movements of the dorso-ventral thoracic walls. 5. No relationship was found between the amplitude of the tracheal pressure deflexions and the extent of thoracic wall movements during fetal breathing.

Se probaron 18 cultivares de maíz para determinar su resistencia al ataque de tres plagas, (gusano de la mazorca, taladrador del tallo de la caña y gusanos de la barba de la mazorca) y a dos enfermedades (roya y tizón). Quince cultivares introducidos de Georgia demostraron menos resistencia a las plagas y a las enfermedades que el Mayorbela, Ibadan A e Ibadan B, que son originarios del Caribe. Se observó una diferencia significativa en la producción y en la razón de infestación de las plagas, pero no de enfermedades, entre las parcelas asperjadas y las no asperjadas. La producción mayor esta aparentemente relacionada con la resistencia a las enfermedades. Es necesario controlar el gusano cogollero para obtener buenos rendimientos. Aspersiones semanales de "methanyl" controlaron el gusano cogollero, pero no el de la mazorca.

Exploratory calculations are presented which indicate that the azimuthal asymmetry in the cross section for scattering of unpolarized electrons by polarized s-state atoms in the presence of spin-orbit interaction, which was predicted by Farago (see abstr. A9432 of 1974), should be measurable for caesium at incident electron energies below about 15 eV.

Polysynaptic reflex excitation of the hind-limb flexor muscles was produced by stimulation of the distal peroneal or common sciatic nerve in ten fetal and six new-born unanaesthetized lambs. In the fetal lambs, stimulation at 1.1-3.25 times threshold for direct activation of the nerve produced a reflex response which was greatest during high-voltage electrocortical activity, being reduced 69 +/- 5.0% (mean +/- S.E. of the mean) during low-voltage electrocortical activity. Reduction of the fetal arterial PO2 from 23.3 +/- 0.58 to 12.2 +/- 0.4 mmHg caused a rapid and reversible reduction of the reflex in all fetal lambs with intact spinal cord, including two whose brain stems were transected at the level of the colliculi. Hypoxia did not alter the amplitude of the reflex in two fetuses in which the spinal cord at L1-2 had been cut several days previously. In new-born lambs reduction of the arterial PO2 to 43 mmHg did not change the reflex amplitude during episodes of quiet wakefulness or slow-wave sleep. Brief reduction of the Pa,O2 to 20-30 mmHg caused a statistically insignificant reduction of reflex amplitude during quiet sleep before behavioural arousal. It is concluded that hypoxaemia activates reticular mechanisms in the pons and medulla of fetal lambs which decrease the excitability of spinal reflex pathways. In the new-born lamb such effects are counteracted or prevented by mechanisms associated with arousal.

Fetal lambs treated with sheep anti-mouse nerve growth factor antibodies (anti-NGF) at 80 days gestation subsequently showed a diminished cardiovascular response to intravenous infusion of tyramine (1 mg/min over 10 min) and no significant change in plasma norepinephrine concentrations as measured by reversed-phase high-pressure liquid chromatography and electrochemical detection. At autopsy at 135 days gestation, catecholamine content of the heart, thyroid, kidney, and ileum was reduced by greater than 70% compared with age-matched control fetuses. The anti-NGF-treated fetuses were thus judged to have impaired sympathetic function. When made hypoxemic (arterial PO2 12-14 Torr) for 1 h at 120 or 130 days gestation, anti-NGF-treated fetuses showed no significant change of arterial pressure, heart rate, or plasma catecholamines, whereas control fetuses showed bradycardia, a 28% increase in arterial pressure, and a 670% increase of plasma norepinephrine concentrations. These results suggest that the increase of arterial pressure that occurs during hypoxemia in fetal lambs between 120 and 135 days gestation is attributable to increased activity of the peripheral sympathetic nervous system. The adrenal medulla appears to contribute to the plasma catecholamine pool at rest, but the lack of increased plasma catecholamines during hypoxia after anti-NGF implies that the adrenal medulla was unable to release catecholamines. Possible reasons for this are discussed.

1. Baroreflex activity was assessed in nine fetal, four new-born and six adult sheep, using the relationship between heart period and arterial pressure. Arterial pressure was raised either by inflating a balloon in the dorsal aorta, by rapid intravenous injection of phenylephrine or methoxamine, or by slow intravenous infusion of methoxamine. 2. In the fetus the three methods gave different estimates of baroreflex sensitivity (balloon, 1.3 +/- 0.7 mmHg; injections, 5.4 +/- 0.5 msec mmHg; infusions, 7.2 +/- 0.9 msec/mmHg) whereas they were comparable in the new-born and adult. 3. Estimates of baroreflex sensitivity were significantly lower in the fetus and new-born than in the adult whichever method was used. 4. In the fetus there were variable changes of heart period when arterial pressure was raised by inflation of the balloon. The responses to injection of phenylephrine or methoxamine were also variable. 5. This variability was not associated with changes in electrocortical activity, the presence or absence of breathing movements or limb movements, or changes of blood gases. 6. In the fetus the heart period frequently did not change unless the arterial pressure was raised by approximately 15 mmHg (to 61 mmHg), suggesting that the threshold for baroreflex activity is above the normal range of arterial pressure before birth.

‘Centennial’ and ‘Jewel’ sweet potato [Ipomoea batatas(L.) Lam.] plants were grown in hydroponic sand culture in either 3.5 or 15 mM nitrogen solutions for 65 days. Petioles, leaf blades, stems, fi...

The effects of 4 ? application levels, 0, 45, 90, and 135 kg N/ha, and 2 cultivars, ‘Centennial’ and ‘Jewel’, on total ? and NO3‐N concentration of leaf blades and NO3‐N concentration of petioles were determined in 2 field experiments. The concentrations of NO3‐N in petioles of ‘Centennial’ plants were much higher than those of ‘Jewel’ plants. Petiole NO3‐N concentrations were more sensitive to differences in soil ? application levels than blade total ? concentrations. Petiole NO3‐N concentrations were also affected by plant age at sampling. While petiole NO3‐N concentration was a reliable indicator of current ? status of the plants, total ? concentration of blades appeared to be a more reliable predictor of yield. Critical concentrations of total ? in blades associated with a 5% reduction in total marketable root yield were 3.0 and 3.2% for ‘Centennial’ and ‘Jewel’, respectively.

Electrocortical and electro-ocular activity, breathing movements and nuchal muscle activity were recorded continuously in the unanaesthetized lamb in utero (95-135 days). Electrocortical activity was recorded simultaneously from various sites. The bi-parietal electrocorticogram gave the clearest differentiation between high- and low-voltage activity. The onset of cortical differentiation from 110 days gestation was attributed to the superimposition of high-voltage electrocortical activity at 3-10 Hz on existing low-voltage activity. Three distinct patterns in the relationships between electrocortical activity, ocular activity breathing movements and nuchal muscle activity were observed at 95-106, 107-114 and 120-135 days. Isocapnic hypoxia caused a diminution in fetal breathing from 95-135 days gestation, quantitatively greater near term. After cortical differentiation, hypoxia caused the appearance of high-voltage activity within 4 min, if low-voltage electrocortical activity was present initially. The relationship, changing with age, between electrocortical activity, breathing movements, ocular and nuchal muscle activity is discussed.

Potential drought resistances of 304 diverse cowpea (Vigna unguiculata (L.) Walp.) genotypes were determined using plants grown in dryland and irrigated plots near Lubbock, Texas, during a severe drought (60 mm rainfall) in 1980. Screening for drought resistance was based on total shoot dry weight 55 and 77 days after planting (DAP). Genotypes were classified as either resistant or susceptible on five criteria: (1) shoot dry weight in dryland plots, 55 and 77 DAP (SDW); (2) percentage reduction in shoot dry weight in dryland plots as compared to shoot dry weight in irrigated plots (SDW%); (3) rate of growth in dryland plots between 55 and 77 DAP (RATE); (4) percentage reduction in rate of growth between dryland and irrigated plots (RATE%); (5) mean productivity expressed as average performance in both environments (MP). Genotypes classified as resistant or susceptible by percentage reduction criteria, such as SDW% and RATE%, tended to perform well in one environment and not in the other. Therefore, identification of drought-resistant germplasm may require screening on the basis of an absolute measurement of performance, such as SDW or RATE, in combination with a percentage reduction criterion, such as SDW% or RATE%. Seven genotypes (TVu 29, TVu 2074, TVu 2157, TVu 2319, TVu 2538, TVu 5150 and TVu 5158) were classified as drought-resistant and four (TVu 1570, TVu 1630, TVu 1819 and TVu 3444) as drought-susceptible by more than three criteria. Improved drought resistance in cowpea via plant breeding appears to be feasible.

A suggestion by Farago (1980) that longitudinally polarised electrons might be produced by scattering of electrons by optically active molecules has been investigated. Although the process analogous to that producing optical activity produces negligible cross sections in a single scattering event, it is suggested that a process in which spin-orbit interaction and molecular asymmetry are present might lead to the desired result.

Previously reported scattering calculations from mercury, including electron exchange effects, are extended by the inclusion of a 'polarization potential' which describes the distortion of the atom by the incident electron. Although a slight improvement in agreement with experiment is obtained, the results indicate that the adiabatic approximation used overestimates this distortion effect rather greatly.

Differential cross sections and spin polarizations for 35-500 eV electrons scattered from mercury have been calculated by the numerical solution of the relativistic Hartree-Fock equations, thus including the effect of exchange but ignoring distortion of the atom and correlation effects. At the upper end of the energy range the inclusion of exchange produces small but significant changes which bring the results into very good agreement with experiment. At lower energies some discrepancies appear, but even at 35 eV good qualitative agreement is obtained.

The polarization state of the photoelectrons emitted by an assembly of ground state alkali atoms illuminated by circularly polarized light is described in terms of the Stokes vector formalism. The results indicate that there are several different experimental approaches available for testing theoretical predictions but they yield the same information about the underlying processes.