Analysis of Fusarium causing dermal toxicosis in marram grass planters

In the European coastal dunes, marram grass (Ammophila arenaria) is planted in order to control sand erosion. In the years 1986 to 1991, workers on the Wadden islands in the Netherlands planting marram grass showed lesions of skin and mucous membranes, suggesting a toxic reaction. Fusarium culmorum dominated the mycoflora of those marram grass culms that were used for planting. This plant material had been cut and stored for more than one week in the open. The Fusarium toxin deoxynivalenol (DON) was detected in the suspect marram grass culms. Isolated F. culmorum strains were able to produce DON in vitro in liquid culture as well as in experimentally inoculated wheat heads. Pathogenicity tests, toxin test as well as RAPD analysis showed that the F. culmorum strains were not specialized for marram grass but may form part of the West-European F. culmorum population infecting cereals and grasses. Storage on old sand-dunes with plant debris may have led to the high occurrence of F. culmorum and contamination with DON. Marram grass culms should be obtained from young plantings on dunes on the seaward slopes and cut culms should not be stored.

Response of growing swine to dietary exposure to pure fumonisin B1 during an eight-week period: growth and clinical parameters

Consumption of corn or corn-based products contaminated with Fusarium moniliforme/fumonisins has been associated with a variety of animal and human diseases and is a major food/feed safety issue. This study focused on the clinical toxicity and performance parameters in growing swing exposed to low to moderate levels of pure fumonisin B1 (FB.) for 8 weeks. Male (castrated) and female pigs were fed diets containing 0,0.1,1.0, and 10 mg FB1/kg diet (ppm). Weight gains and feed consumption were measured weekly. Blood samples were collected throughout the study, and various clinical and hematological parameters were measured. Because fumonisins are potent inhibitors of sphingolipid biosynthesis, sphinganine and sphingosine concentrations were determined in the liver, lung, and kidney. Organ weights and carcass quality were measured at the end of the trial. In general, male pigs were more adversely affected by FB1 in the diet than females. The average daily gain for males decreased by 8% for pigs fed 1.0 ppm and by 11% at 10.0 ppm, when compared to the control (0 ppm). Males fed 0.1 ppm showed an erratic growth pattern during the first 5 weeks of the experiment. Feed consumption for the same animals was somewhat higher than that of the controls during each of the first 4 weeks but thereafter was 6-7% lower each week as compared to controls. Female pigs fed FB1-diets showed a general enhancement of feed consumption until week 4. Among clinical chemistry parameters, cholesterol increased in males for the 1.0 and 10.0 ppm diets as compared to controls after 2 weeks, while the levels in both sexes were elevated for the 1.0 ppm diet only by the end of the experiment. Serum liver enzyme concentrations were altered during week 2 only. Changes were observed in the weight of the pancreas and adrenals for male pigs fed FB1 diets as compared to controls. The free sphinganine to free sphingosine ratio (biomarker of exposure in FB1-consuming animals) increased in all three organs for the 10 ppm diet, regardless of sex. The study indicated that FB1 can cause different effects at each dose level, at concentrations as low as 0.1 ppm (showing erratic growth) followed by a reduced growth and biochemical abnormalities in blood (1.0 ppm) and sphingolipid alterations in tissues (10.0 ppm). Some of these effects occurred below the exposure level that caused alteration in sphingolipid metabolism.

Fumonisin B1 toxicity in male Sprague-Dawley rats

Male rats were gavaged with fumonisin B1 (FB1) once daily for 11 consecutive days at doses of 0, 1, 5, 15, 35, and 75 mg FB1/kg body weight. Urine osmolality (at 5-75 mg FB1/kg) and organic ion transport in kidney slices (at 5-75 mg FB1/kg) were reduced. Urinary excretion of protein (at 15-75 mg FB1/kg) and of the enzymes LDH (at 5-75 mg FB1/kg), NAG (at 5-75 mg FB1/kg) and GGT (at 15-75 mg FB1/kg) were increased. These findings were indicative of glomerular and tubular toxicity. Histopathologic changes in the kidney consisted of necrosis of tubular epithelia of variable extent accentuated in the inner cortex. These changes were present at 1 and 5 mg FB1/kg and were more pronounced at 15-75 mg FB1/kg. Serum enzymes indicative of hepatotoxicity (ALT, GGT) were elevated compared to controls at 75 mg FB1/kg only. There were noticeable increases in mitotic figures in hepatocytes at 35-75 mg FB1/kg, while single cell necroses were increasingly numerous from 15-75 mg FB1/kg. The kidneys were considered to be the primary target organs in this study.

Middle cerebral artery blood flow velocity in patients with cirrhosis

BACKGROUND

Brain dysfunction is common in patients with advanced liver disease; it is often manifested as hepatic encephalopathy, but its cause is not clearly understood.

METHODOLOGY

Intracranial blood flow velocity parameters, including peak systolic velocity, end diastolic velocity and mean velocity of both middle cerebral arteries were measured by transcranial Doppler ultrasonography in 37 patients with cirrhosis without encephalopathy (16 Child's A, 10 Child's B and 11 Child's C) and 12 normal controls. The cause was alcohol-related in 24 and non-alcohol-related in 13.

RESULTS

No significant differences in any of the Doppler parameters were detected in Child's group A when compared with controls. However, a statistically significant decrease in middle cerebral artery blood flow velocity was evident when Child's B and C patients without clinically apparent encephalopathy were compared with controls irrespective of the cause. Our results demonstrate that intracranial blood flow is abnormal in patients with advanced liver disease without clinically apparent encephalopathy.

Bioactive isocoumarins and related metabolites from conifer endophytes

Six new [1-4, 7, 9] and two known [6 and 8] metabolites have been isolated from culture filtrates of conifer endophyte strains of Canoplea elegantula. Their structures have been determined by spectroscopic means. Compound 1 was toxic to spruce budworm cells, and both 1 and 3 were toxic to spruce budworm larvae.

The regulation of acetylated microtubules during outgrowth from cultured neurons of the snail, Helisoma

Axonal stumps of cultured Helisoma trivolvis neurons express abundant acetylated microtubules, as a subset of total microtubules. Label completely disappears from the axonal remnants within approximately 1 day, and reappears in newly extended neurites over the course of the next 3-4 days, first in the proximal neurite as short, isolated segments. Acetylated microtubules occur in the neuritic shaft, but never in growth cones or membranous veils. Thus, acetylated microtubules are very labile to the signals generated by axotomy, and their proximodistal re-expression occurs at well separated sites within the neurite as it matures.

The adverse drug reaction: a clinical opportunity for pharmacists

A program is presented that gives the pharmacist the clinical opportunity to assess and evaluate adverse drug reactions in the hospital setting. An adverse drug reaction protocol is discussed that addresses reporting and patient care issues. The pharmacist performs adverse drug reaction assessment at the patient bedside as part of a multidisciplinary team consisting of the pharmacist, nurse, and physician. The protocol provides a method of concurrent adverse drug reaction monitoring and involves the patient in the reporting process.

An amino-terminal domain containing hydrophobic and hydrophilic sequences binds the signal recognition particle receptor alpha subunit to the beta subunit on the endoplasmic reticulum membrane

The signal recognition particle receptor consists of two subunits of 72 kDa (SR alpha) and 30 kDa (SR beta). Assembly of SR alpha on the endoplasmic reticulum membrane can occur independent of the signal recognition particle-mediated translocation pathway. To identify the sequences within SR alpha necessary for membrane binding, a series of amino-terminal and internal deletion mutants was constructed and translated in a cell-free system. In addition, nascent SR alpha polypeptides of varying lengths were generated by cycloheximide treatment of translation reactions. Microsome binding assays performed on these polypeptides revealed a membrane binding domain consisting of the amino-terminal 140 residues of SR alpha. This domain includes the two hydrophobic sequences originally proposed to bind to membranes and a highly charged region not previously implicated in membrane assembly. Furthermore, the domain forms a protease-resistant folding unit that after proteolysis can target and anchor onto microsomes. Extraction of microsomal SR alpha at high pH supplemented with 1 M NaSCN suggests that SR alpha and the membrane binding domain are not integrated in the endoplasmic reticulum membrane. The membrane binding domain is also the major site of tight binding with SR beta, suggesting that SR beta plays a role in the membrane assembly of SR alpha.

Differential binding of vascular cell-derived proteoglycans (perlecan, biglycan, decorin, and versican) to the beta-amyloid protein of Alzheimer's disease

Previous studies have demonstrated the immunolocalization of perlecan, a specific heparan sulfate proteoglycan, to the beta-amyloid protein (A beta)-containing amyloid deposits within the walls of blood vessels (i.e., congophilic angiopathy) in Alzheimer's disease (AD) brain. In the present investigation, the differential binding of previously characterized endothelial cell (EC)- and smooth muscle cell (SMC)-derived PGs to A beta was examined to determine whether the accumulation of A beta in cerebrovascular amyloid deposits may be due to its interactions with perlecan. Pretreatment of AA amyloidotic splenic and liver tissue sections with synthetic A beta (1-28) produced strong immunoreactivity with A beta antibodies at tissue sites enriched in perlecan which was partially removed by pretreatment with heparitinase, but not by chondroitin ABC lyase. [35S]-Sulfate labeled proteoglycans (PGs) derived from cultured ECs and SMCs bound to affinity columns containing A beta (1-28) or (1-40), with virtually no binding to A beta (40-1) (reverse peptide), beta-amyloid precursor protein (410-429), or bovine serum albumin. Characterization of EC and SMC PGs bound to A beta (1-28) revealed strong binding by perlecan, weak binding by decorin and biglycan, two dermatan sulfate proteoglycans, and lack of binding by versican/PG-M, a large chondroitin sulfate proteoglycan. Binding of 125I-labeled perlecan to A beta (1-28) was strongly inhibited by isolated perlecan and to a lesser extent by heparin, but not by chondroitin-6-sulfate or unsulfated dextran sulfate. Heparitinase treatment decreased, but did not eliminate the binding of 125I-labeled perlecan to A beta (1-28). Scatchard analysis of the interaction of A beta (1-28)- and EC-derived perlecan in solid-phase assays indicated high-affinity (Kd = 8.3 x 10(-11) M) and lower-affinity (Kd = 4.2 x 10(-8) M) binding sites, with approximately 1 mol of perlecan binding 1.8 mol of A beta. A significant decrease in binding of EC-derived perlecan to A beta (1-28) was observed when a sequence within the putative heparin-binding motif of A beta (His13His14Gln15Lys16) was replaced by the uncharged peptide sequence, Gly13Gly14Gln15Gly16, indicating a perlecan binding site on A beta near the postulated alpha-secretase site (at Lys-16). Overall, the results indicate that specific vascular cell-derived PGs differentially interact with A beta, and that the interactions of highest affinity occur between A beta and binding sites on both the core protein and glycosaminoglycan chains of perlecan.(ABSTRACT TRUNCATED AT 400 WORDS)

The evaluation of the wave-form analysis capability of a new strain-gauge intracranial pressure MicroSensor

Both laboratory and clinical trials have indicated the reliability of a new catheter-tip, strain-gauge intracranial pressure transducer. We report on the results of bench tests comparing the wave-form analysis capabilities of the new Codman intracranial pressure MicroSensor and a similar strain-gauge transducer. Good agreement was found between the two sensors with no significant nonlinearity or hysteresis over a measured pressure range from 0 to 100 mg Hg. Under "fluid-filled" conditions, the MicroSensor showed good reproduction of an arterial pressure wave form; when spectral analysis was used to analyze the two sensor types and break them down into harmonic components, no significant differences could be found for any of the first 10 amplitude and phase harmonics. If proven to stay robust after long-term clinical use, this sensor may be a useful alternative to the existing transducer systems for routinely monitoring the intracranial pressure and its wave form.

Chromosomal location of genes for stem rust resistance derived from 'Waldron' wheat

The chromosomal locations of genes for resistance to stem rust (Puccinia graminis Pers.: Pers. f. sp. tritici Eriks. & E. Henn.) in the wheat (Triticum aestivum L.) cultivar 'Waldron' (WDR) were determined by monosomic analyses. Wheat lines WDR-B1, -C2, -E4, and -F1,which have single genes for resistance to stem rust derived previously from WDR sel. 'Little Club', were crossed onto a complete set of 21 'Chinese Spring' monosomics. The F2 and backcross-F1 (BC1F1) seedlings from each of the 84 crosses were tested for reaction to culture 111-SS2 (CRL-LCBB) of stem rust, and a few selected segregants were analyzed cytologically for chromosome number. The F2 from 2 crosses of WDR-C2, -E4 and -F1 and the BC1F1 from 2 crosses of WDR-F1 were tested also with culture Or11c (CRL-QBCN). Significant deviations from disomic ratios towards monosomic ratios in the F2 and BC1F1 were used to determine which chromosomes carried the genes for resistance. Cytological analyses of certain BC1F1 and susceptible F2 plants were used to help identify the location of the genes for rust resistance. WDR-B1 has a gene, herein designated Sr41, for resistance on chromosome 4D. WDR-C2 has a gene on chromosome 7 A that may be the same as one previously designated SrWld2. WDR-E4 has a gene on chromosome 2A, possibly SrWld1, which is effective against most or all North American stem rust cultures. WDR-F1 has a gene on chromosome 6B that is the same as or similar to Sr11.

Wheat lines monogenic for resistance to stem rust from the wheat cultivar 'Waldron'

The Triticum aestivum L. cultivar 'Waldron' has long lasting resistance to most North American stem rust (Puccinia graminis Pers.:Pers. f. sp. tritici Eriks. and E. Henn.) isolates. The objective of this research was to develop wheat lines monogenic for resistance to stem rust from 'Waldron' using allelism tests and tests for reaction to a series of ten stem rust cultures having a range of virulences. Twelve lines homozygous for single resistance genes were selected as parents of a diallel cross to test for allelism among genes for resistance. We identified 6 lines or groups of lines (WDR-A1, the WDR-B1 and WDR-B2 group, the WDR-C1 and WDR-C2 group, WDR-D1, the WDR-E1, WDR-E2, WDR-E3, and WDR-E4 group, and WDR-F1) that carried different single genes for resistance from 'Waldron'. A seventh line (WDR-G1) probably has two genes for resistance, one in common with WDR-C1 and WDR-C2. The gene in the WDR-E group is probably the same as SrWld1, and the one in WDR-F1 the same as Sri11. 'Waldron' probably has two or more genes for resistance to stem rust that previous genetic studies did not detect.

Nicotine phase-advances the circadian neuronal activity rhythm in rat suprachiasmatic nuclei explants

In vivo studies reported that cholinergic agents affect mammalian circadian rhythmicity. To study phase resetting properties of cholinergic compounds more directly, we carried out experiments in rat suprachiasmatic nuclei slices. Compounds were added to the perfusate for 1 h at specific phases of the circadian cycle. On the following day, the time of peak neuronal activity, a measure of the phase of the endogenous circadian pacemaker, was assessed by means of extracellular recording in the suprachiasmatic nuclei. The peak of neuronal activity occurred at circadian time 5.8 +/- 0.7 (mean +/- 95% confidence limits) in the control slice (circadian time 0: lights-on). Ten-micromolar carbachol had no effect on the phase of the circadian rhythm when given at circadian times 6 and 15, while at circadian time 21 a phase advance of one hour was observed. By contrast, 10 microM nicotine significantly phase advanced (> 1 h) the neuronal circadian rhythm at all but one experimental circadian phase. The circadian times of maximal nicotinic phase advances were 15 (+2.6 h) and 21 (+2.8 h). A concentration response curve for nicotine was generated and pharmacological blocking experiments were performed at circadian time 15. The estimated maximum response of nicotine was 3.4 h, and the estimated concentration for half maximal response was 5 microM. The Hill coefficient (= 1.08) indicated that the effects of nicotine may be explained by a single receptor occupancy model. Mecamylamine (20 microM) almost completely antagonized the nicotinic phase-advances, whereas tetrodotoxin (1 microM) or high Mg2+ (10 mM) did not significantly attenuate the nicotinic phase-advances.(ABSTRACT TRUNCATED AT 250 WORDS)

A formant bandwidth estimation procedure for vowel synthesis [43.72.Ja]

The specification of vowel formant bandwidths for speech synthesis has been inconsistent in the past, perhaps due to the difficulty of measuring formant bandwidths in natural speech and the possible perceptual insignificance of formant bandwidths on the intelligibility of synthetic speech. Here, regression equations are presented for the estimation of formant bandwidths based on measurements from natural speech which is based only on formant center frequency and independent of other formant values. Current usage, as well as comparison with another well-known estimation algorithm suggests that the new procedure should be quite acceptable for some types of speech synthesis.

The beta subunit of the signal recognition particle receptor is a transmembrane GTPase that anchors the alpha subunit, a peripheral membrane GTPase, to the endoplasmic reticulum membrane

The signal recognition particle receptor (SR) is required for the cotranslational targeting of both secretory and membrane proteins to the endoplasmic reticulum (ER) membrane. During targeting, the SR interacts with the signal recognition particle (SRP) which is bound to the signal sequence of the nascent protein chain. This interaction catalyzes the GTP-dependent transfer of the nascent chain from SRP to the protein translocation apparatus in the ER membrane. The SR is a heterodimeric protein comprised of a 69-kD subunit (SR alpha) and a 30-kD subunit (SR beta) which are associated with the ER membrane in an unknown manner. SR alpha and the 54-kD subunits of SRP (SRP54) each contain related GTPase domains which are required for SR and SRP function. Molecular cloning and sequencing of a cDNA encoding SR beta revealed that SR beta is a transmembrane protein and, like SR alpha and SRP54, is a member of the GTPase superfamily. Although SR beta defines its own GTPase subfamily, it is distantly related to ARF and Sar1. Using UV cross-linking, we confirm that SR beta binds GTP specifically. Proteolytic digestion experiments show that SR alpha is required for the interaction of SRP with SR. SR alpha appears to be peripherally associated with the ER membrane, and we suggest that SR beta, as an integral membrane protein, mediates the membrane association of SR alpha. The discovery of its guanine nucleotide-binding domain, however, makes it likely that its role is more complex than that of a passive anchor for SR alpha. These findings suggest that a cascade of three directly interacting GTPases functions during protein targeting to the ER membrane.

NEsting by the hawsbill turtle (Eretmochelys imbricata) on Milman Island, Great Barrier Reef, Australia

Nesting biology of hawksbill sea turtles (Eretmochelys imbricata) is described with morphometric and meristic measurements collected from 365 turtles over 76 nights of beach patrols on Milman I. The nesting season was already in progress when the study began in January and continued after the research team left in March 1991. Average renesting interval was 14.2 days, and the hawksbill turtles laid an average of 2.6 clutches during the study period. Nest sites were located most commonly under trees (67.2%). Average curved carapace length was 81.7 cm, width was 70.6 cm, and weight after laying was 50.3 kg. Mean clutch size was 124 eggs. Eggs had an average diameter of 3.48 cm and an average weight of 25.7 g. Emergence success rate was 79.9% for hawksbill hatchlings, which had an average straight carapace length of 3.96 cm and weight of 13.3 g. Incubation temperatures were monitored and sex ratios determined in four clutches, two in shaded and two in unshaded sand. The sexes of 25 hatchlings from each clutch were identified. Two unshaded clutches produced 92% and 100% female hatchlings while two shaded clutches produced 64% and 44% female hatchlings. Statistical differences were not found between the presented hawksbill turtle curved carapace length, weight after laying and clutch size and those collected elsewhere in Queensland by earlier studies.

Phytotoxic effect of deoxynivalenol and gibberella ear rot resistance of corn

The Fusarium graminearum mycotoxin deoxynivalenol was shown to be more phytotoxic to corn genotypes susceptible to gibberella ear rot than resistant genotypes. The toxin caused greater damage to the membranes of the susceptible genotypes, as evidenced by the release of Na and K ions into solution. Isolated protoplasts of ear rot-resistant genotypes were able to bind more radiolabelled deoxynivalenol than those of susceptible genotypes, providing a partial explanation for the membrane tolerance to the toxin. The results are discussed in relation to the role of resistance to this phytotoxin and tolerance to gibberella ear rot.

Integrated multimodality monitoring in the neurosurgical intensive care unit

The selection of variables for continuous monitoring in the neurosurgical intensive care unit is based upon the requirement for constant perfusion and oxygenation of the brain and knowledge of the frequency and prognostic significance of abnormal values. Both arterial and intracranial pressure must be considered in the form of cerebral perfusion pressure. Body temperature and arterial oxygen saturation are essential to monitoring. Measurement of jugular venous oxygen saturation and cerebral blood flow velocity provide information of value in determining the source of raised intracranial pressure, the most appropriate means of treating it, and the safety of therapy.

Determination of fumonisins in milk

Fumonisin B1 (FB1) and fumonisin B2 (FB2) were determined in milk by liquid chromatography (LC) following immunoaffinity column cleanup. Recoveries from milk spiked with 5-50 ng each fumonisin/ml averaged 79-109%. The aminopentol hydrolysis product of FB1 (AP1) was determined by LC after cleanup on a C18 solid phase phase extraction column; mean recoveries were 69-83% at spiking levels of 50-100 ng AP1/ml milk. Detection limits were of the order 3-7 ng/ml for FB1 and FB2, and 20-25 ng/ml for AP1. A stability study showed no losses of FB1 and FB2 in milk under conditions of freezing, refrigeration and boiling. A transmission study using four cows dosed with pure FB1 either orally (1.0 and 5.0 mg FB1/kg b.w.) or by i.v. injection (0.05 and 0.20 mg FB1/kg b.w.) showed no detectable residues of FB1 or AP1 in the milk, with or without hydrolytic treatment with beta-glucuronidase/sulfatase to liberate any conjugates.

Secondary metabolites of Penicillium bilaii strain PB-50

A phosphate-solubilizing strain of Penicillium bilaii was tested for the production of gliotoxin and other toxic compounds. The strain was fermented under five different conditions to allow the expression of various metabolites, including gliotoxin. These included Czapek-yeast extract medium under both shaken and still conditions as well as Czapek-yeast extract/malt extract/peptone medium and sucrose/glycerol medium in shake flasks. In addition, culture filtrate from an industrial fermentation of the fungus was examined. No gliotoxin was produced in any of the media. No other expected P. bilaii metabolites were found. Three compounds were identified in all samples: dibutyl phthalate, 1-(4-hydroxy-phenyl)ethanone and 4-hydroxy-3,6-dimethyl-2H-pyran-2-one. The production of other metabolites was dependent on the culture conditions. Two hyalodendrin derivatives were found in some fermentations and two related compounds were tentatively identified. None of the compounds found have been reported as toxic. The identity of the culture was confirmed by comparison with the ex-type culture of P. bilaii.

Chemical treatment of carpets to reduce allergen: a detailed study of the effects of tannic acid on indoor allergens

Tannic acid (TA), a protein-denaturing agent, has been reported to reduce allergen levels in house dust and is marketed for that purpose as 1% and 3% solutions. We investigated the effects of TA on dust allergens by using monoclonal antibody-based ELISAs for mite (Der p I, Der f I, and group II) and cat (Fel d I) allergens. Initial studies confirmed that TA reduced allergen levels in carpet dust. However, when dust samples from treated carpets are extracted in saline solution, residual TA redissolves and may interfere with the assessment of allergens. In the laboratory, concentrations of TA as low as 0.1% inhibited the assays, but this effect may be prevented by addition of 5% bovine serum albumin (BSA). After treatment of dust samples in the laboratory with 3% TA, the apparent reductions in Der p I and Der f I levels were 89% and 96%, respectively, but when the samples were extracted in 5% BSA the reductions were 74% and 92%. Similar effects were seen with dust samples from carpets treated with TA. In an extreme case in which a carpet had been repeatedly treated with TA, the apparent concentration of Der p I was < 0.05 microgram/gm without BSA and 2.1 and 8.4 microgram/gm when extracted in the presence of 1% and 5% BSA, respectively. Our testing of the ability of TA to denature Fel d I demonstrated an 80% reduction in allergen, but only in samples with an initial concentration of less than 200 micrograms Fel d I/gm dust.(ABSTRACT TRUNCATED AT 250 WORDS)

Growth cone collapse and neurite retraction from cultured Helisoma neurons in response to antibody Fab fragments against an extracellular matrix protein

Helisoma neurons require a factor(s) present in conditioned medium (CM), for successful neurite outgrowth in vitro. A approximately 300 kDa Helisoma extracellular matrix (ECM) protein has been identified in CM and is necessary for neurite initiation. Here we show that purified approximately 300 kDa ECM protein supports outgrowth. Furthermore, anti- approximately 300 kDa Fab fragments cause a rapid, dose-dependent decrease in outgrowth when added to neurons already growing in CM, culminating in growth cone collapse and neurite retraction at 200 micrograms/ml. Collapsing growth cones rapidly lost lamellipodia and filopodia transformed into long filamentous strands. Contortion of microtubules in retracting neurites into serpentine shapes, apparently by compressive forces, suggests that large-scale microtubule depolymerization is not a prerequisite for growth cone retraction. These results imply that substrate-bound approximately 300 kDa CM protein is necessary and sufficient for CM-stimulated growth cone initiation and neurite elongation from Helisoma neurons.

Serotonergic phase advances of the mammalian circadian clock involve protein kinase A and K+ channel opening

The mammalian circadian clock located in the suprachiasmatic nuclei (SCN) continues to oscillate when isolated in a brain slice preparation, and can be phase shifted in vitro by a variety of serotonergic (5-HTergic) agents. We have previously shown that 5-HT and a 5-HT agonist, quipazine, induce phase advances in the daytime and phase delays at night; the phase advances are mimicked by the 5-HT1A-selective agonist 8-OH-DPAT, by analogs of cyclic AMP, and by treatments that increase endogenous levels of cyclic AMP. Here we investigated the intracellular pathway through which these daytime phase advances occur. We find that quipazine- and 8-OH-DPAT-induced phase advances are blocked by two inhibitors of the cyclic AMP-dependent protein kinase, PK-A (H8 and Rp-cAMPS) as well as by a variety of K+ channel blockers (BaCl2, apamin, and charybdotoxin). Furthermore, we confirm previous work showing that a cyclic AMP analog induces phase advances in the daytime, and show that these phase advances are also blocked by BaCl2 and apamin. Finally, we show that a K+ ionophore induces similar phase advances in the subjective day, and these phase advances are blocked by Rp-cAMPS. These results indicate that both activation of PK-A and opening of K+ channels are necessary for 5-HT-induced phase advances of the SCN circadian clock. We propose a model that can account for our results.

A possible glial role in the mammalian circadian clock

The primary mammalian circadian clock is located within the suprachiasmatic nuclei (SCN), but the cellular organization of the clock is not yet known. We investigated the potential role of glial cells in the clock mechanism by determining whether disrupting glial activity affects the in vitro circadian rhythm of neuronal activity and the in vivo circadian activity rhythm in rats. We used two agents (octanol and halothane) that block gap junctions, and one (fluorocitrate) that inhibits glial metabolism. All three agents disrupted the circadian pattern of neuronal activity. Octanol flattened the rhythm at the highest concentration (200 microM) and induced a small phase delay at a lower concentration (66 microM). Halothane and fluorocitrate induced ultradian rhythmicity. Fluorocitrate injected into the SCN of an intact rat induced arrhythmicity for about 1 week, after which the rhythm reappeared with a 1.6 h delay. These results suggest that glia play an important role in the SCN circadian clock.

Persistence of circadian rhythmicity in hibernating ground squirrels

The body temperatures (Tb) of golden-mantled ground squirrels maintained under constant dim light (< 20 1x red light) at an ambient temperature of 10 degrees C were monitored via telemetry throughout the hibernation season. During euthermia, when Tb ranged from 34 to 39 degrees C, these animals exhibited robust circadian Tb rhythms. During bouts of hibernation, when Tb rhythms persisted, although the amplitudes of the rhythms were considerably dampened compared with euthermia. The periods of the intrabout Tb rhythms were within the ranges observed during euthermia and were stable within an individual bout but varied between hibernation bouts. Arousals from hibernation occurred at a fixed phase angle of the Tb cycle. Once the period of an intrabout Tb rhythm was determined, it was possible to predict the timing of arousal from the hibernation bout to within 1 h of any 24-h period. This study confirms previous speculation about the persistence of circadian rhythms in golden-mantled ground squirrels during deep hibernation and demonstrates that the circadian system is involved in the timing of periodic arousals from hibernation.

Thermal effects on neuronal activity in suprachiasmatic nuclei of hibernators and nonhibernators

The temperature sensitivity of neuronal firing rates in the suprachiasmatic nuclei (SCN) of the hypothalami of rats and ground squirrels was studied in vitro. SCN from euthermic squirrels were studied during the hibernation season (winter) and during the summer. SCN from hibernating squirrels were also studied. Most properties of SCN cells from hibernators and nonhibernators were similar. Warm- and cold-sensitive neurons were observed in all groups, but cold-sensitive neurons were more common in SCN from hibernating squirrels. No evidence for temperature compensation of firing rate was accumulated; no cell was observed to fire below 16.6 degrees C. If the persistence of circadian rhythmicity is a function of action potential-dependent neurotransmission from the SCN, these results suggest that deep hibernation (5-17 degrees C) should be characterized by an absence of circadian fluctuation in temperature. Two possible adaptations for the shallow torpor seen at somewhat higher temperatures were observed in the SCN: 1) a relatively large population of cold-sensitive neurons and 2) a population of neurons with very high activation energies. Activation energy analysis suggested that most of the temperature-sensitive properties of these cells could be explained in terms of the thermal sensitivity of the sodium channel.

Cause, distribution and significance of episodes of reduced cerebral perfusion pressure following head injury

A group of 74 patients with head injury (54 severe, 17 moderate and 3 minor) had continuous monitoring of both arterial and intracranial pressure with computer-based registration of these pressures, cerebral perfusion pressure and other variables. In 60 patients cerebral perfusion pressure CPP fell below 60 mm Hg for periods of 5 minutes or longer. The distribution over time of these reductions in CPP during up to 12 days of monitoring was studied, and each episode of reduced CPP was attributed to a fall in arterial pressure, an increase in intracranial pressure, or both. Two clusters of reduced CPP were found, one during the first 24 hours of monitoring, when reduced CPP was mainly caused by a reduction in arterial pressure, and the other at 5 or 6 days after injury, when reduced CPP was due mainly to an increase in intracranial pressure. There was a significant correlation between low CPP due to reduced arterial pressure and the Injury Severity Score (p < 0.001), suggesting that resuscitative measures may have been less than optimal in these cases. There was also significant correlation between the duration of low CPP and low arterial pressure and an adverse outcome from injury as assessed at 6, 12 and 24 months after injury (p < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Interaction of E. coli Ffh/4.5S ribonucleoprotein and FtsY mimics that of mammalian signal recognition particle and its receptor

The mechanism of protein translocation across the endoplasmic reticulum membrane of eukaryotic cells and the plasma membrane of prokaryotic cells are thought to be evolutionarily related. Protein targeting to the eukaryotic translocation apparatus is mediated by the signal recognition particle (SRP), a cytosolic ribonucleoprotein, and the SRP receptor, an endoplasmic reticulum membrane protein. During targeting, the 54K SRP subunit (M(r) 54,000; SRP54), a GTP-binding protein, binds to signal sequences and then interacts with the alpha-subunit of the SRP receptor (SR alpha), another GTP-binding protein. Two proteins from Escherichia coli, Ffh and FTsY, structurally resemble SRP54 and SR alpha. Like SRP54, Ffh is a subunit of a cytosolic ribonucleoprotein that also contains the E. coli 4.5S RNA. Although there is genetic and biochemical evidence that the E. coli Ffh/4.5S ribonucleoprotein has an SRP-like function, there is no evidence for an SR alpha-like role for FtsY. Here we show that the Ffh/4.5S ribonucleoprotein binds tightly to FtsY in a GTP-dependent manner. This interaction results in the stimulation of GTP hydrolysis which can be inhibited by synthetic signal peptides. These properties mimic those of mammalian SRP and its receptor, suggesting that the E. coli Ffh/4.5S ribonucleoprotein and FtsY have functions in protein targeting that are similar to those of their mammalian counterparts.

Analysis of intracerebral hematoma shapes by numerical computer simulation using the finite element method

The distortion and stress distribution in the brain caused by putaminal hemorrhage were estimated by computer stimulation using the finite element method (FEM). The two-dimensional model of a single cerebral hemisphere contained cortex, white matter, caudate nucleus, lenticular nucleus, thalamus, falx, and lateral ventricle. Five types of intracerebral hemorrhage were modeled at different locations in the lenticular nucleus. The models generated putaminal hematomas of various shapes influenced by the location of the bleeding points. Hematomas caused deformation of the brain, collapse of the lateral ventricle, and destruction of the internal capsule. The stress distribution revealed various patterns influenced by the site of bleeding. The stress in the area of the internal capsule corresponded to the extent of destruction of the internal capsule. This study suggests that FEM modeling of putaminal hemorrhage can provide a useful simulation.

Production and purification of fumonisins from a stirred jar fermenter

The production, isolation and purification of fumonisins from 10 litre liquid cultures are described. Measurements of sucrose, fructose and glucose consumption, oxygen demand, dry weight increase, CO2, and fumonisin production were taken every 48 hours. The specific productivity of fumonisins was found to be similar to that reported for corn cultures but purification was much simpler, yielding an 89% recovery. The method developed for the purification of fumonisins from liquid culture was also applied to a corn culture, resulting in a 70.1% recovery.

Chloride channel block phase advances the single-unit activity rhythm in the SCN

The mammalian suprachiasmatic nuclei (SCN) contain a circadian pacemaker that exhibits a 24 h rhythm in single-unit activity in vivo and in vitro. Chloride channel block by a saturating concentration of picrotoxin at either CT6 or CT15 produces large phase advances in the SCN single-unit activity rhythm in vitro. These phase advances are not affected by simultaneous blockade of voltage-sensitive sodium and calcium channels by TTX and magnesium. Thus, the effects of picrotoxin appear to be mediated by direct blockade of the chloride channel, rather than subsequent membrane depolarization. GABA-A receptor-mediated chloride flux may be part of the mechanism of circadian timekeeping.

Pharmacokinetic fate and pathological effects of 14C-fumonisin B1 in laying hens

Presence of fumonisin B1 (FB1), a major metabolite of Fusarium moniliforme, in corn is of great concern to both human and animal health because of its wide range of toxicity. The pharmacokinetics of FB1 was studied in laying hens following oral and intravenous administration of 14C-labelled FB1. After iv dosing (2.0 mg = 23.68 kBq/kg bw) plasma radioactivity underwent a very rapid bi-exponential decline (t1/2 alpha = 2.5 +/- 0.3 min; t1/2 beta = 48.8 +/- 11.2 min) with negligible levels measured after 4-6 hr. Mean value for the apparent volume of distribution at steady state (Vdss) was 18.27 ml/kg, apparent volume of central compartment (Vd beta) was 82.20 ml/kg and plasma clearance was 1.18 ml/min/kg. At 24 hr post-dosing only trace residues were present in liver, kidney, and cecum. When dosed by the oral route (2.0 mg = 47.36 kBq/kg bw), systemic absorption of fumonisin appeared to be poor (F = 0.71 +/- 0.5%) with peak plasma concentrations of only 40-145 dpm/ml (equivalent to 28-103 ng FB1 and/or metabolites per ml) between 1.5 and 2.5 hr. At 24 hr post-dosing only trace amounts were present in crop, liver, kidney, small intestine, and cecum. In both orally and iv dosed birds almost all (97.7 +/- 3.73%) of the radioactivity was recovered in excreta by the end of the 24 hr experiment period and no residues were found in eggs laid during the 24 hr post-dosing period.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute subdural haematoma secondary to ruptured intracranial aneurysm: diagnosis and management

Acute subdural haematoma secondary to a ruptured intracranial aneurysm may lead to coma or sudden death. We describe five cases encountered in our department over the last 3 years emphasizing the differential diagnosis and approaches to management.

Role of intracranial pressure monitoring in severely head-injured patients without signs of intracranial hypertension on initial computerized tomography

Previous studies have suggested that only a small proportion (< 15%) of comatose head-injured patients whose initial computerized tomography (CT) scan was normal or did not show a mass lesion, midline shift, or abnormal basal cisterns develop intracranial hypertension. The aim of the present study was to re-examine this finding against a background of more intensive monitoring and data acquisition. Eight severely head-injured patients with a Glasgow Coma Scale score of 8 or less, whose admission CT scan did not show a mass lesion, midline shift, or effaced basal cisterns, underwent minute-to-minute recordings of arterial blood pressure, intracranial pressure (ICP), and cerebral perfusion pressure (CPP) derived from blood pressure minus ICP. Intracranial hypertension (ICP > or = 20 mm Hg lasting longer than 5 minutes) was recorded in seven of the eight patients; in five cases the rise was pronounced in terms of both magnitude (ICP > or = 30 mm Hg) and duration. Reduced CPP (< or = 60 mm Hg lasting longer than 5 minutes) was recorded in five patients. Severely head-injured (comatose) patients whose initial CT scan is normal or does not show a mass lesion, midline shift, or abnormal cisterns nevertheless remain at substantial risk of developing significant secondary cerebral insults due to elevated ICP and reduced CPP. The authors recommend continuous ICP and blood pressure monitoring with derivation of CPP in all comatose head-injured patients.

Management and long-term outcome following subarachnoid haemorrhage and intracranial aneurysm surgery in elderly patients: an audit of 199 consecutive cases

To address the question of managing subarachnoid haemorrhage (SAH) in the older patient, the management and outcome of 199 consecutive patients aged > or = 60 years with a confirmed diagnosis of subarachnoid haemorrhage (n = 186) or an unruptured intracranial aneurysm (n = 13) were reviewed. In seven patients, the cause of the SAH was an arterio-venous malformation and these were excluded from further analysis. Angiography was performed in 141 patients with a complication rate of 2.1%. Angiography was not performed in 51 patients and, in this cohort, the in-patient mortality rate was 68.6% and only 27.5% had a favourable outcome at discharge. Operation was not performed in 21 patients with demonstrated aneurysms for a variety of reasons. In this group, the in-patient mortality rate was 47.6% and 38.1% had a favourable outcome at discharge. Eighty-one patients in good neurological grade underwent surgery for a ruptured aneurysm and six patients underwent surgery for a symptomatic unruptured aneurysm. The surgical mortality was 1.1% and a favourable outcome at discharge was achieved in 83.9% of patients. Thirty-three patients were angiographic negative and there was a favourable outcome in 97% of this group. The management mortality in these selected patients admitted to the Department of Clinical Neurosciences was 24.4% and a favourable outcome was recorded in 66.2% of patients. Long-term follow-up (median 40 months, range 3-120 months) was obtained in 97% of discharged patients. The probability of survival at 60 months for patients in good condition at discharge was 0.826 (95% confidence interval 0.722-0.894).(ABSTRACT TRUNCATED AT 250 WORDS)

GTP binding and hydrolysis by the signal recognition particle during initiation of protein translocation

The signal recognition particle (SRP) consists of one RNA and six protein subunits. The N-terminal domain of the 54K subunit contains a putative GTP-binding site, whereas the C-terminal domain binds signal sequences and SRP RNA. Binding of SRP to the signal sequence as it emerges from the ribosome creates a cytosolic targeting complex containing the nascent polypeptide chain, the translating ribosome, and SRP. This complex is directed to the endoplasmic reticulum membrane as a result of its interaction with the SRP receptor, a membrane protein composed of two subunits, SR alpha and SR beta, each of which also contains a GTP-binding domain. In the presence of GTP, SRP receptor binding to SRP causes the latter to dissociate from both the signal sequence and the ribosome. GTP is then hydrolysed so that SRP can be released from the SRP receptor and returned to the cytosol. Here we show that the 54K subunit (M(r) 54,000) of SRP (SRP54) is a GTP-binding protein stabilized in a nucleotide-free state by signal sequences, and that the SRP receptor both increases the affinity of SRP54 for GTP and activates its GTPase. We propose that nucleotide-mediated conformational changes in SRP54 regulate the release of signal sequences and the docking of ribosomes at the endoplasmic reticulum.

A comparison of the Glasgow Coma Scale and the Swedish Reaction Level Scale

The Glasgow Coma Scale (GCS) and the Swedish Reaction Level Scale (RLS85), two level-of-consciousness scales used in the assessment of patients with head injury, were compared in a prospective study of 239 patients admitted to a regional head injury unit over a 4-month period. Assessments were made by nine staff members ranging from house officer to registrar, after briefing about the two scales. Data were also collected on age, nature of injuries, surgical treatment, and condition at discharge or transfer using the Glasgow Outcome Scale. Both the GCS and the RLS85 reliably identified comatose patients and those with minor head injury, but were much less effective in defining the response level in patients considered to have a moderate head injury. Only 41% of the patients allocated to a moderate-head-injury category by the GCS and the RLS85 were common to both groups. Where a mismatch occurred, neither scale allocated patients to a 'better' or 'worse' category more frequently than the other. Assessment of patients' conscious levels using the GCS was difficult in only two cases. One patient had facial injuries, and the other was intubated. The RLS85 was reported by all users to be simpler to use than the GCS, but the latter is much more widespread in use. Both scales function well in cases of severe and minor head injury, but have weaknesses when defining moderate head injury. Level-of-consciousness scales are only an aid to assessment and the final choice between the two scales must remain a matter of personal or departmental preference.