Evaluation of Soybean Entries in the Pan-African Trials for Response to Coniothyrium glycines, the Cause of Red Leaf Blotch

Red leaf blotch (RLB), caused by the fungus Coniothyrium glycines, is an important disease of soybean known to cause yield losses across soybean-growing regions in Africa. Fungicides are one option to manage this disease, but utilization of host resistance may be a better option suited for smallholder soybean farmers in Africa. Fifty-nine soybean entries were evaluated for RLB severity in nine field locations in Ethiopia, Kenya, Uganda, and Zambia. Disease incidence was 100% and disease severity differed (P < 0.01) among entries at eight of the nine locations. Mean severity ratings ranged from 1.4 to 3.2 based on a 0-to-5 scale, with higher disease severities recorded in Ethiopia followed by Zambia. Eight of the 59 entries were common to all nine locations and had severity ratings ranging from 1.6 to 2.9. The cultivar SC Signal had the lowest RLB severity ratings in the combined analysis over locations. Based on correlations of weather variables to RLB severity, mean rainfall from planting to 30 days before assessment date had a positive correlation (r = 0.70; P = 0.035), as did mean morning maximum wind speed (r = 0.88; P = 0.016). Other variables, such as temperature and relative humidity, did not correlate to RLB severity. This is the most comprehensive report to date on the occurrence of RLB in the region, which for the first time demonstrates an association between rainfall and wind speed with RLB severity. It also represents the first extensive report evaluating soybean genotypes for resistance against RLB in multiple environments.

Study of the absorption coefficient of graphene-polymer composites

In this work, we have prepared a series of polydimethylsiloxane (PDMS) composites containing various graphene flakes loadings (0.02-2 wt%), and their broadband optical properties are being investigated. We demonstrate the tunability and evolution of transmittance and reflection spectra of the composites in a wide spectral range (0.4-200 μm) as a function of graphene content. Using these data we derive the broadband wavelength-dependent absorption coefficient (α) values. Our results show that α is roughly constant in the visible and IR ranges, and, surprisingly, is approximately one order of magnitude lower in the terahertz regime, suggesting different terahertz radiation scattering mechanism in our composite. Our material could be useful for applications in optical communication, sensing or ultrafast photonics.

Efficacy and safety of simultaneous vaccination with two modified live virus vaccines against porcine reproductive and respiratory syndrome virus types 1 and 2 in pigs

The objective of the study was to compare responses of pigs vaccinated with a PRRS MLV vaccine against PRRSV-1 or PRRSV-2 with the responses of pigs vaccinated simultaneously with both vaccines. Furthermore, the efficacy of the two PRRSV MLV vaccination strategies was assessed following challenge. The experimental design included four groups of 4-weeks old SPF-pigs. On day 0 (DPV0), groups 1-3 (N=18 per group) were vaccinated with modified live virus vaccines (MLV) containing PRRSV-1 virus (VAC-T1), PRRSV-2 virus (VAC-T2) or both (VAC-T1T2). One group was left unvaccinated (N=12). On DPV 62, the pigs from groups 1-4 were mingled in new groups and challenged (DPC 0) with PRRSV-1, subtype 1, PRRSV-1, subtype 2 or PRRSV-2. On DPC 13/14 all pigs were necropsied. Samples were collected after vaccination and challenge. PRRSV was detected in all vaccinated pigs and the majority of the pigs were positive until DPV 28, but few of the pigs were still viremic 62 days after vaccination. Virus was detected in nasal swabs until DPV 7-14. No overt clinical signs were observed after challenge. PRRSV-2 vaccination resulted in a clear reduction in viral load in serum after PRRSV-2 challenge, whereas there was limited effect on the viral load in serum following challenge with the PRRSV-1 strains. Vaccination against PRRSV-1 had less impact on viremia following challenge. The protective effects of simultaneous vaccination with PRRSV Type 1 and 2 MLV vaccines and single PRRS MLV vaccination were comparable. None of the vaccines decreased the viral load in the lungs at necropsy. In conclusion, simultaneous vaccination with MLV vaccines containing PRRSV-1 and PRRSV-2 elicited responses comparable to single vaccination and the commercial PRRSV vaccines protected only partially against challenge with heterologous strains. Thus, simultaneous administration of the two vaccines is an option in herds with both PRRSV types.

Ghrelin modulates encoding-related brain function without enhancing memory formation in humans

Ghrelin regulates energy homeostasis in various species and enhances memory in rodent models. In humans, the role of ghrelin in cognitive processes has yet to be characterized. Here we show in a double-blind randomized crossover design that acute administration of ghrelin alters encoding-related brain activity, however does not enhance memory formation in humans. Twenty-one healthy young male participants had to memorize food- and non-food-related words presented on a background of a virtual navigational route while undergoing fMRI recordings. After acute ghrelin administration, we observed decreased post-encoding resting state fMRI connectivity between the caudate nucleus and the insula, amygdala, and orbitofrontal cortex. In addition, brain activity related to subsequent memory performance was modulated by ghrelin. On the next day, however, no differences were found in free word recall or cued location-word association recall between conditions; and ghrelin's effects on brain activity or functional connectivity were unrelated to memory performance. Further, ghrelin had no effect on a cognitive test battery comprising tests for working memory, fluid reasoning, creativity, mental speed, and attention. In conclusion, in contrast to studies with animal models, we did not find any evidence for the potential of ghrelin acting as a short-term cognitive enhancer in humans.

Soybean aphid intrabiotype variability based on colonization of specific soybean genotypes

The soybean aphid, Aphis glycines Matsumura (Hemiptera: Aphididae), is one of the most destructive insect pests on soybeans in the United States. One method for managing this pest is through host plant resistance. Since its arrival in 2000, 4 aphid biotypes have been identified that are able to overcome soybean aphid resistance (Rag) genes. A soybean aphid isolate collected from Moline, Illinois readily colonized soybean plants with the soybean aphid resistance gene Rag2, unlike biotypes 1 and 2, but similar to soybean aphid biotype 3. Two no-choice experiments compared the virulence of the Moline isolate with biotype 3. In both experiments, differences in aphid population counts were not significant (P > 0.05) on soybean genotypes LD08-12957a (Rag2) and LD11-5413a (Rag2), but the aphid counts for the Moline isolate were significantly (P < 0.05) lower than the aphid counts for the biotype 3 isolate on the soybean genotypes Dowling (Rag1), LD05-16611 (Rag1), LD11-4576a (Rag1), and PI 567598B (rag1b and rag3). The Moline isolate was a variant of aphid biotype 3, which is the first report showing that soybean aphid isolates classified as the same biotype, based on virulence against specific Rag genes, can differ in aggressiveness or ability to colonize specific host genotypes.

Inhibitory effects of stilbenes on the growth of three soybean pathogens in culture

The effects of resveratrol and pterostilbene on in vitro growth of three soybean pathogens were tested to determine whether these stilbenic compounds could potentially be targets to increase innate resistance in transgenic soybean plants. Growth of Macrophomina phaseolina, Rhizoctonia solani, and Sclerotinia sclerotiorum was measured on solid and in liquid media amended with resveratrol and pterostilbene (concentration in the media of resveratrol at 100 μg/ml and pterostilbene at 25 μg/ml). All three fungi were very sensitive to pterostilbene in potato dextrose agar (PDA), which reduced colony area of each of the three pathogens to less than half of the control 3 days after incubation. The three fungal pathogens were less sensitive to resveratrol compared with pterostilbene; however, area under the curve (AUC) calculated from colony areas measured over 3 days was significantly (P < 0.05) less than the control for S. sclerotiorum and R. solani on PDA with resveratrol or pterostilbene. AUC for M. phaseolina on PDA with pterostilbene was significantly (P < 0.05) lower than the control whereas, on PDA with resveratrol, AUC for M. phaseolina was lower than the control but the difference was nonsignificant (P > 0.05). AUC for all three fungi was significantly lower (P < 0.05) on PDA with pterostilbene than with resveratrol. In potato dextrose broth (PDB) shake cultures, AUC for all three fungi was significantly (P < 0.01) lower in pterostilbene than in the control. AUC for R. solani and S. sclerotiorum was significantly lower (P < 0.01) in resveratrol than the control, whereas AUC for M. phaseolina in resveratrol was lower, but not significantly (P > 0.05) different from the control. AUC in pterostilbene was highly significantly (P < 0.01) lower than in resveratrol for M. phaseolina and significantly (P < 0.05) lower for R. solani but the difference for S. sclerotiorum was nonsignificant (P > 0.05). There was a trend for lower mass accumulation of all three fungi in either pterostilbene or resveratrol compared with the control during the course of the experiment; however, S. sclerotiorum appeared to recover from the effects of pterostilbene between days 2 and 4. Results of biochemical analyses of the PDB over time indicated that the three fungi degraded resveratrol, with nearly 75% reduction in concentration in M. phaseolina, 80% in S. sclerotiorum, and 60% in R. solani PDB cultures by day 4 of fungal growth. M. phaseolina and S. sclerotiorum were able to resume growth after early inhibition by resveratrol after its concentration was reduced in the cultures through degradation, whereas R. solani was less efficient in resveratrol degradation and was not able to overcome its inhibitory effects on growth. The capacity to degrade pterostilbene was lowest in M. phaseolina compared with S. sclerotiorum and R. solani and the recovery of M. phaseolina cultures after initial growth inhibition by pterostilbene was minimal. The potential products of resveratrol and pterostilbene degradation by fungi were identified to be dimers and various oxidation products.

A Cut-Stem Inoculation Technique to Evaluate Soybean for Resistance to Macrophomina phaseolina

Charcoal rot of soybean is caused by the fungal pathogen Macrophomina phaseolina. Effective and reliable techniques to evaluate soybean for resistance to this fungus are needed to work toward a management scheme that would utilize host resistance. Three experiments were conducted to investigate the use of a cut-stem inoculation technique to evaluate soybean genotypes for resistance to M. phaseolina. The first experiment compared aggressiveness of M. phaseolina isolates collected from soybean on different soybean genotypes. Significant (P < 0.05) differences among the isolates and genotypes for relative area under disease progress curve (RAUDPC) were found without a significant isolate-genotype interaction. The second experiment compared 14 soybean genotypes inoculated with M. phaseolina in multiple trials conducted in two environments, the greenhouse and growth chamber. Significant (P < 0.05) differences among environments and highly significant (P < 0.001) differences among soybean genotypes for RAUDPC were found. The environment-genotype interaction was nonsignificant (P > 0.05). Soybean genotypes DT97-4290, DT98-7553, DT98-17554, and DT99-16864 had significantly (P < 0.05) lower RAUDPC than 7 of the 14 genotypes. The third experiment evaluated resistance in selected Phaseolus spp. and soybean genotypes. The range of RAUDPC for Phaseolus spp. was similar to that of soybean. The Phaseolus lunatus 'Bush Baby Lima' had significantly (P < 0.05) lower RAUDPC than P. vulgaris genotypes evaluated. The cut-stem inoculation technique, which has several advantages over field tests, successfully distinguished differences in aggressiveness among M. phaseolina isolates and relative differences among soybean genotypes for resistance to M. phaseolina comparable with results of field tests.

Decreasing concentration of interstitial glucose in REM sleep in subjects with normal glucose tolerance

AIMS

Sleep is divided into two major stages, non-rapid eye movement (NREM) and rapid eye movement (REM), which are distinct in various neuroendocrine respects. NREM/REM cycles influence insulin and glucagon secretion; however, glucose concentrations in REM compared with NREM have not been directly explored. The aim was to investigate the differences in glucose concentrations in interstitial fluid (IGC) between NREM/REM cycles using a continuous glucose monitoring system (CGMS).

METHODS

Thirteen subjects were eligible for analysis out of the 28 enrolled. All underwent standard polysomnography for the assessment of sleep stages and the exclusion of sleep apnoea syndrome with CGMS and subsequent morning oral glucose tolerance test (exclusion of glucose intolerance or diabetes).

RESULTS

The IGC in REM fell in 12 out of the 13 subjects, whereas the IGC in NREM increased in eight out of the 13 subjects. Therefore, the mean change of IGC differed in direction between sleep stages: -0.028 (-0.045 to -0.011) for REM vs. 0.005 (-0.012 to 0.017) for NREM [median (QR), P = 0.007, n = 13], with the mean difference of 0.038 mmol/l x 5 min(-1) (95% confidence interval 0.012, 0.064). The mean glucose concentration in REM sleep was lower than in NREM: 4.29 +/- 1.00 vs. 4.53 +/- 0.90 mmol/l (mean +/- sd, P = 0.003, n = 13).

CONCLUSIONS

The decrease in IGC in REM compared with NREM sleep, with lower absolute values, may arise from different physiological events observed in these sleep stages. The REM-related decline in glucose concentrations may be a risk factor for nighttime hypoglycaemia.

G/A polymorphism at -258 of the hepatic glucokinase promoter is not associated with decreased birth weight in preterm neonates

BACKGROUND

A high percentage of preterm neonates are born small for gestational age (SGA). These children show a high morbidity and mortality after birth and often develop insulin resistance with ensuing impaired glucose metabolism in adulthood. Since insulin is important for intrauterine growth, fetal insulin resistance might also influence birth weight of preterm neonates.

OBJECTIVES

A common polymorphism in the promoter region of the human hepatic glucokinase (-258) is associated with a decreased promoter activity, an enhanced insulin secretion, and hypertension and hepatic insulin resistance in adults. In this pilot study we wanted to investigate whether the G/A polymorphism at -258 of the hepatic glucokinase promoter has an effect on birth weight of preterm neonates and therefore might constitute a genotype leading to low birth weight and metabolic defects.

METHODS

We enrolled 106 preterm neonates in our study. 44 of them were SGA and 62 AGA neonates. We extracted DNA from a buccal swab and identified the polymorphism by PCR-ARMS.

RESULTS

We found no difference in the prevalence of the polymorphism in either groups.

CONCLUSION

The polymorphism at -258 of the fetal hepatic glucokinase promoter is most probably not of a major relevance in the pathophysiology of low birth weight in preterm neonates.

Distribution of the Components of the NCEP ATP III-defined Metabolic Syndrome in Newly Diagnosed Diabetes and Non-diabetes Caucasian Subjects; Implications for Metabolic Syndrome Prevention and Treatment

The study aimed at assessing the relationship between five components of the NCEP ATP III-defined metabolic syndrome (MS) in diabetes and non-diabetes MS subjects.

METHODS

Prevalence of MS and its components was assessed in 1586 adult Caucasian individuals, without known diabetes. Oral glucose tolerance test (OGTT) with 75 g glucose according to WHO protocol was conducted in all subjects.

RESULTS

MS was diagnosed in 419 persons (prevalence 26.4%), including 123 subjects with newly diagnosed diabetes. Diabetes subjects presented with higher plasma triglycerides and slightly more pronounced abdominal obesity as well as higher fasting plasma insulin, which in all reflected insulin resistance-related character of MS pathophysiology. However, the distribution of MS components was largely uneven in diabetes and non-diabetes subjects. Elevated plasma triglycerides and low HDL cholesterol were the most prevalent components. The least often found component was elevated fasting plasma glucose (FPG). Non-diabetes subjects with elevated FPG were more likely to present with three or four other components than with two of them only. In contrast, those with high plasma triglycerides, low plasma HDL cholesterol or increased waist circumference were all more likely to have two rather than three or four other MS components. Subjects with diabetes presented significantly more often with four or five MS components when compared with non-diabetes subjects.

CONCLUSIONS

The components of metabolic syndrome are not equally prevalent in Caucasian population. Lipid disorders are most often found and glucose intolerance is the least prevalent MS component. Glucose intolerance and diabetes occurred in a more complex setting, concomitantly with three or four other MS components, suggesting that diabetes is associated with more advanced stages of MS. These findings may have important implications for MS prevention and treatment.

[Retropharyngeal tendinitis. Differential diagnosis in the management of acute neck pain]

Neck pain is frequent and can be a symptom of numerous differential diagnoses with quite different diagnostic and therapeutic consequences. A 37-year-old woman reported acute neck pain aggravated by movements of the cervical spine and head and by swallowing. Clinical examination showed pronounced neck stiffness. T2-weighted MRI demonstrated high-intensity edema and effusion localized prevertebrally in the area of the superior part of the longus colli muscle. Computed tomography of this region demonstrated prevertebral calcification leading to the diagnosis of retropharyngeal tendinitis. Nonsteroidal antiphlogistic drugs led to rapid improvement of clinical signs and symptoms. Retropharyngeal tendinitis should be considered in patients with acute neck pain.

The impact of ultraviolet radiation on the vertical distribution of zooplankton of the genus Daphnia

The vertical migration of zooplankton into lower and darker water strata by day is generally explained by the avoidance of visually orienting predators, mainly fish; however, it is unclear why daily zooplankton migration has been maintained in fishless areas. In addition to predation, ultraviolet radiation-a hazardous factor for zooplankton in the surface layers of marine and freshwater environments-has been suspected as a possible cause of daytime downward migration. Here we test this hypothesis by studying several Daphnia species, both in a controlled laboratory system and under natural sunlight in an outdoor system. We selected Daphnia species that differed in their pigmentation as both melanin and carotenoids have been shown to protect Daphnia from ultraviolet light. All Daphnia species escaped into significantly deeper water layers under ultraviolet radiation. The extent to which the daphnids responded to this radiation was inversely linked to their pigmentation, which reduced ultraviolet transmission. These results suggest that ultraviolet avoidance is an additional factor in explaining daytime downward migration. Synergistic benefits might have shaped the evolution of this complex behaviour.

Aza-analogs of 8-styrylxanthines as A2A-adenosine receptor antagonists

In the present study we synthesized aza-analogs of 8-styrylxanthines, in which the ethenyl bridge is replaced by an imine, amide, or azo function, in order to investigate structure-activity relationships of the 8-substituent of A2A-selective xanthine derivatives. Thus, various 8-substituents were combined with theophylline or caffeine, respectively, and affinities of the novel compounds for adenosine A1- and A2a-receptors were determined and compared with those of analogous 8-styrylxanthine derivatives. 8-(Benzylideneamino)caffeine derivatives exhibited high affinity and selectivity for A2A-adenosine receptors, but were unstable in aqueous buffer solution at physiological pH values. 8-(Phenylazo)caffeine derivatives were less potent than corresponding 8-styrylcaffeine derivatives at adenosine receptors. The most potent azo compound of the present series was 8-(m-chlorophenylazo)caffeine (14b) exhibiting a Ki value of 400 nM at A2A-adenosine receptors and 20-fold selectivity versus A1-receptors. Due to the facile synthetic access to 8-(phenylazo)xanthine derivatives, which are obtained by coupling of 8-unsubstituted xanthines with phenyldiazonium salts, 14b may be an interesting new lead compound for the development of more potent and selective A2A-antagonists with azo structure.

Intravascular oxygen distribution in subcutaneous 9L tumors and radiation sensitivity

Phosphorescence quenching was evaluated as a technique for measuring PO2 in tumors and for determining the effect of increased PO2 on sensitivity of the tumors to radiation. Suspensions of cultured 9L cells or small pieces of solid tumors from 9L cells were injected subcutaneously on the hindquarter of rats, and tumors were grown to between 0.2 and 1.0 cm in diameter. Oxygen-dependent quenching of the phosphorescence of intravenously injected Pd-meso-tetra-(4-carboxyphenyl) porphine was used to image the in vivo distribution of PO2 in the vasculature of small tumors and surrounding tissue. Maps (512 x 480 pixels) of tissue oxygen distribution showed that the PO2 within 9L tumors was low (2-12 Torr) relative to the surrounding muscle tissue (20-40 Torr). When the rats were given 100% oxygen or carbogen (95% O2-5% CO2) to breathe, the PO2 in the tumors increased significantly. This increase was variable among tumors and was greater with carbogen compared with 100% oxygen. Based on irradiation and regrowth studies, carbogen breathing increased the sensitivity of the tumors to radiation. This is consistent with the measured increase in PO2 in the tumor vasculature. It is concluded that phosphorescence quenching can be used for noninvasive determination of the oxygenation of tumors. This method for oxygen measurements has great potential for clinical application in tumor identification and therapy.

Oxygen pressure distribution in the heart in vivo and evaluation of the ischemic "border zone"

Quantitation of the oxygen pressure distribution in the heart provides an accurate definition of metabolically viable cells adjacent to ischemic injury. By injection of a phosphorescent oxygen probe into the blood of newborn piglets and illumination of the heart with monochromatic light, a series of images of the heart were collected with use of a gated intensified CCD camera. These sets of images were used to calculate two-dimensional maps of the oxygen pressure in the epicardial microvasculature. Occlusion of a distal arterial vessel resulted in a hypoxic area containing a central focus of near-zero oxygen pressure bordered by tissue with diminished but nonzero oxygen pressures. These border zones extended for several millimeters from the hypoxic core, with the oxygen pressures progressively increasing from the focus to the normoxic region. The maps of oxygen distribution obtained by phosphorescence imaging provide rapid and quantitative measure of the oxygen pressures in the beating heart in vivo. They accurately show the degree of oxygen deprivation and the extent of an ischemic border zone that may respond to treatment.

Synergy between tumor necrosis factor alpha and interleukin-1 in the induction of sickness behavior in mice

Like interleukin-1, recombinant human tumor necrosis factor alpha (TNF alpha) has been found to decrease social exploration and induce weight loss in mice in a dose and time-dependent manner. The present study was carried out to study the interaction between these two cytokines. Mice were injected IP with subthreshold doses of TNF alpha (2.5 micrograms/mouse) and IL-1 beta (50 ng/mouse). Social exploration was decreased 2 and 4 h after injection of TNF and IL-1, but body weight was not affected. Subthreshold doses of TNF alpha (90 ng/mouse) and IL-1 beta (100 pg/mouse) were also injected intracerebroventricularly (ICV). Social exploration was decreased 1.5 and 3 h after injections of the two cytokines and body weight was decreased for 6 h. To test the possibility of central induction of IL-1 by TNF alpha, mice pretreated with IL-1 receptor antagonist (IL-1ra, 1.8 micrograms/mouse, ICV) were injected with 90 ng TNF alpha. Pretreatment with IL-1ra antagonized the depressive effect of TNF alpha on behavior, but had no effect on weight loss induced by this cytokine. These results suggest that TNF alpha-induced behavioral alterations are mediated by endogenously released IL-1, whereas metabolic changes are dependent on the release of other cytokines.

Anxiolytic-like effects of a selective 5-HT1A agonist, S20244, and its enantiomers in mice

The action of a selective 5-HT1A agonist S20244 and its two enantiomers (+)-S20499 and (-)-S20500 were assessed in mice. The animals were confronted with a free exploratory test especially adapted to reveal behavioural sedation, and with a two-box light/dark choice situation validated for the detection of anti-anxiety agents. These drugs were found to have anxiolytic properties at low doses, like benzodiazepines. Furthermore, the drugs exhibited sedative effects at higher doses. These results closely resemble those we found after administration of two other 5-HT1A agonists, 8-OH-DPAT and MDL 73005EF (NeuroReport, 1, 267-270, 1990).

Oxygen distribution in the retinal and choroidal vessels of the cat as measured by a new phosphorescence imaging method

The oxygen tension in the vessels of the retina and optic nerve head has been measured noninvasively with a new phosphorescence imaging method. A phosphorescent oxygen-dependent probe, injected into the bloodstream of cats, was excited with a flash of light and the phosphorescence lifetime of the probe was measured. A simple Stern-Volmer relationship was used to convert lifetime to oxygen tension, and two-dimensional maps of intravascular oxygen tension were produced. We describe the equipment and the methodology for obtaining oxygen maps.

Monitoring of the oxygen pressure in the blood of live animals using the oxygen dependent quenching of phosphorescence

Oxygen dependent quenching of phosphorescence is a powerful new method for measuring oxygen pressure in biological systems (see Vanderkooi et al, J. Biol. Chem. 262 (1987) 5476; Wilson et al, J. Biol. Chem. 263 (1988) 2712). This technology has now been extended to include measurements of the phosphorescent of oxygen probes dissolved in the blood as a complex with albumin. In this communication, we report on a new microcomputer controlled phosphorimeter in which the tissue is illuminated by a flash lamp and the phosphorescence observed through flexible light guides designed to make measurements in regions down to approximately 1 mm in diameter. Measurements of the phosphorescence lifetimes of these probes in regions of tissue necessarily report a distribution of oxygen pressures due to the presence of blood in veins and arteriols as well as that present in the capillaries. Thus the phosphorescence decay is the sum of a continuum of exponentials with different decay constants and initial intensities. The complete phosphorescence decay curve is digitized using a 12 bit, 1 MHz A/D board and deconvoluted using numerical methods to yield a distribution of exponentials contributing to the total decay curve.

Effect of hyperventilation on oxygenation of the brain cortex of neonates

A new phosphorescence imaging method (Rumsey et al, Science (1988) 1649) has been used to continuously monitor the oxygen pressure in the blood of the cerebral cortex of newborn pigs. The animals' blood pressure was continuously measured and PaCO2, PaO2 and arterial blood pH were measured periodically. The oxygen pressure in the blood was quantitatively determined for regions of about 100 um square within the image (from a total field of about 3 mm diameter). It was observed that during hyperventilation, which lowered PaCO2 and increased pH of the blood, oxygen pressure decreased in proportion to the decrease in PaCO2. For example, hyperventilation which decreased PaCO2 from its normal value of 40 Torr to 10 Torr caused a rapid (within 5 minutes) decrease in oxygen pressure in the blood of capillaries and veins to approximately 1/4 of normal.

m-Chlorophenylpiperazine enhances neophobic and anxious behaviour in mice

1-(3-Chlorophenyl)piperazine (mCPP) reduced novelty-seeking behaviour as well as the number of rears in mice confronted with a free exploratory test. Moreover, mCPP was found to decrease the time spent by mice in the lit box and the number of transitions in a two-box light/dark choice situation validated for the detection of anxiolytic or anxiogenic drugs. These results suggest that mCPP enhances emotional responses towards novel and aversive places. Since mCPP has been reported as a 5-HT1C receptor agonist, it can be hypothesized that increased activity of serotonin may play a role in regulating certain forms of emotional behaviour in animals.

Effect of hyperventilation on oxygenation of the brain cortex of newborn piglets

A new phosphorescence imaging method (Rumsey et al. Science Wash. DC 241: 1649-1651, 1988) has been used to continuously monitor the PO2 in the blood of the cerebral cortex of newborn pigs. A window was prepared in the skull and the brain superfused with artificial cerebrospinal fluid. The phosphorescent probe for PO2, Pd-meso-tetra(4-carboxyphenyl)porphine, was injected directly into the systemic blood. The phosphorescence of the probe was imaged, and the lifetimes were measured using flash illumination and a gated video camera. The PO2 in the blood of the veins and capillary beds of the cortex was calculated from the lifetimes. Systemic blood pressure was continuously monitored while the systemic arterial PCO2, PO2, and blood pH were measured periodically. The PO2 in the blood was quantitated for 60- to 200 microns2 regions within the image (from a total field of approximately 3 mm diam). The PO2 in the microvasculature was not uniform across the viewing field but increased or decreased in each region independently of the other regions. Thus at any point in time the PO2 in a region could be substantially above or below the average value. During hyperventilation, which lowered arterial PCO2 and increased pH of the blood, the average PO2 decreased in proportion to the decrease in arterial PCO2. For example, hyperventilation, which decreased arterial PCO2 from its normal value of 40 Torr to 10 Torr, caused a rapid (within 5 min) decrease in PO2 in the blood of capillaries and veins to approximately one-third of normal.

Piperazine derivatives of dimethylxanthines. IV. Reaction of beta,gamma-epoxypropyldimethylxanthines with piperazines

In the reaction of 7-resp. 1-beta,gamma-epoxyproplderivatives of theophylline (Th) or theobromine (Tb) with piperazine and N-monoalkyl or monoarylpiperazines the corresponding 7-resp. 1-beta-hydroxy-gamma-piperazinopropyl-Th (1-8) resp. Tb (9-16) were formed. In preliminary screening some of the new compounds showed strong antagonism with histamine H1 receptor and with endogenous histamine.