Volcanic glass from the 1.8 ka Taupo eruption (New Zealand) detected in Antarctic ice at ~ 230 CE.

Chemical anomalies in polar ice core records are frequently linked to volcanism; however, without the presence of (crypto)tephra particles, links to specific eruptions remain speculative. Correlating tephras yields estimates of eruption timing and potential source volcano, offers refinement of ice core chronologies, and provides insights into volcanic impacts. Here, we report on sparse rhyolitic glass shards detected in the Roosevelt Island Climate Evolution (RICE) ice core (West Antarctica), attributed to the 1.8 ka Taupo eruption (New Zealand)-one of the largest and most energetic Holocene eruptions globally. Six shards of a distinctive geochemical composition, identical within analytical uncertainties to proximal Taupo glass, are accompanied by a single shard indistinguishable from glass of the ~25.5 ka Oruanui supereruption, also from Taupo volcano. This double fingerprint uniquely identifies the source volcano and helps link the shards to the climactic phase of the Taupo eruption. The englacial Taupo-derived glass shards coincide with a particle spike and conductivity anomaly at 278.84 m core depth, along with trachytic glass from a local Antarctic eruption of Mt. Melbourne. The assessed age of the sampled ice is 230 ± 19 CE (95% confidence), confirming that the published radiocarbon wiggle-match date of 232 ± 10 CE (2 SD) for the Taupo eruption is robust.

Survival of presolar p-nuclide carriers in the nebula revealed by stepwise leaching of Allende refractory inclusions.

The 87Rb-87Sr radiochronometer provides key insights into the timing of volatile element depletion in planetary bodies, yet the unknown nucleosynthetic origin of Sr anomalies in Ca-Al-rich inclusions (CAIs, the oldest dated solar system solids) challenges the reliability of resulting chronological interpretations. To identify the nature of these Sr anomalies, we performed step-leaching experiments on nine unmelted CAIs from Allende. In six CAIs, the chemically resistant residues (0.06 to 9.7% total CAI Sr) show extreme positive µ84Sr (up to +80,655) and 87Sr variations that cannot be explained by decay of 87Rb. The extreme 84Sr but more subdued 87Sr anomalies are best explained by the presence of a presolar carrier enriched in the p-nuclide 84Sr. We argue that this unidentified carrier controls the isotopic anomalies in bulk CAIs and outer solar system materials, which reinstates the chronological significance of differences in initial 87Sr/86Sr between CAIs and volatile-depleted inner solar system materials.

Comment on "Rapid cooling and cold storage in a silicic magma reservoir recorded in individual crystals".

Rubin et al (Reports, 16 June 2017, p. 1154) proposed that gradients in lithium abundance in zircons from a rhyolitic eruption in New Zealand reflected short-lived residence at magmatic temperatures interleaved with long-term "cold" (<650°C) storage. Important issues arise with the interpretation of these lithium gradients and consequent crystal thermal histories that raise concerns about the validity of this conclusion.

Nuclear Thimet oligopeptidase is coexpressed with oestrogen receptor alpha in hypothalamic cells and regulated by oestradiol in female mice.

Thimet oligopeptidase (EC 3.4.24.15; also called EP24.15 and TOP; referred to here as TOP) is a neuropeptidase involved in the regulation of several physiological functions including reproduction. Among its substrates is gonadotrophin-releasing hormone (GnRH), an important hypothalamic hormone that regulates the synthesis and release of oestradiol and facilitates female sexual behaviour. Using immunohistochemistry, we found that TOP is expressed in the nucleus of cells throughout the female mouse brain, and in high levels in steroid-sensitive regions of the hypothalamus, which is consistent with previous findings in male rats. Furthermore, dual-label immunofluorescence revealed that TOP and oestrogen receptor alpha (ERalpha) coexpress in several reproductively-relevant brain regions, including the medial preoptic area (mPOA), arcuate nucleus (ARC), ventrolateral portion of the ventromedial hypothalamic nucleus (VMNvl) and the midbrain central grey (MCG). Previous studies in rats have shown that oestradiol decreases hypothalamic TOP levels or activity, possibly potentiating the effects of GnRH. In the present study, analysis by immunohistochemistry revealed that oestradiol decreased TOP immunoreactivity in the VMNvl, whereas no differences were detected in the mPOA, ARC or median eminence. Overall, the present findings indicate that TOP is coexpressed with ERalpha, and oestradiol regulates TOP expression in a brain region-specific manner in female mice, providing neuroanatomical evidence that TOP may function in reproductive physiology and/or behaviour.

Cognitive function is not impaired in people with a long history of migraine: a blinded study.

Little is known about the long-term consequences of migraine for cognitive functioning. This study compared older migraine patients with matched controls on four measures of cognitive ability, in a blinded design. Migraine patients and case-matched controls were recruited from the database records of a pre-existing study of ageing. Data were available from four tests of cognitive ability: verbal/arithmetic problem solving, spatial problem solving, processing speed, and vocabulary. There were no significant differences between the mean scores of migraine and control groups on any of the four cognitive tests. In addition, there were no significant differences between migraine and control groups in the effect of age on any of the four tests. A long history of migraine does not compromise scores on the four cognitive tests used in this study. These tests are predictive of memory and executive functioning in cognitive ageing, but it remains possible that lower-level cognitive processes, particularly as assessed by visual tasks, may be vulnerable to migraine.

Effect of the methodology on circulating peptides determination and consequences on net flux measurements across the gastrointestinal tract of sheep.

Two methodologies for the measurement of peptide amino acids (PAA) in blood were compared to evaluate their effects on the measurement of the net flux of peptides across the gastrointestinal tract of sheep. These methods consisted of a chemical deproteinization of blood samples with sulfosalicylic acid (1.6 M, 0.1 ml for 1 ml of sample) or perchloric acid (1 M, 1 ml for 1 ml of sample) followed by ultrafiltration through a 3,000-Da cut-off filter (SSA + UF3 kD) or gel filtration through a Sephadex G-15 column (1,500-Da cut-off filter; PCA + G-15), respectively, prior to PAA analysis. Peptide concentrations as determined by amino acid concentrations before and after hydrolysis of samples were slightly greater with the SSA + UF3 kD (991 microM) than with the PCA + G-15 (605 microM) methodology. However, both methodologies gave similar net portal-drained viscera flux data in sheep fed on alfalfa pellets with histidine as the only significant uptake of peptide amino acid.

Subclinical infection with the nematode Trichostrongylus colubriformis increases gastrointestinal tract leucine metabolism and reduces availability of leucine for other tissues.

Gastrointestinal (GI) tract leucine metabolism was measured in 6- to 9-mo-old lambs subjected to trickle infection with Trichostrongylus colubriformis larvae and in separate animals that were not infected. Animals prepared with a jejunal catheter and with indwelling catheters into the aorta and the portal- (PDV) and mesenteric- (MDV) drained viscera were infused simultaneously with [1-13C] and [5,5,5-2H3] leucine to determine GI tract sequestration of leucine from arterial and luminal amino acid pools by tracer and tracee arteriovenous concentration differences. Leucine oxidative losses and net fluxes were also determined across the GI tract. Infection had no detectable effect on whole-body leucine flux, but it increased total GI tract leucine sequestration by 24% (P<.05) and GI tract oxidative losses of leucine by 22 to 41% (P<.01). Net PDV fluxes of leucine were decreased by 20 to 32% during the infection. The infection did not alter either the proportion of precursor leucine used by GI tract metabolism that was derived from the arterial leucine pool (.84 to .88) or the proportional sequestration of digesta-derived leucine during "first pass" absorptive metabolism (.12 to .18). These findings help to elucidate the metabolic basis for the reduced growth rates and nitrogen retention observed when animals are subjected to subclinical nematode infection.

Absorption of amino acids from the intestine and their net flux across the mesenteric- and portal-drained viscera of lambs.

Experiments were conducted to compare the rates of apparent absorption (disappearance) of individual essential amino acids (EAA) from the small intestine with their net fluxes across the mesenteric- (MDV) and portal- (PDV) drained viscera in sheep given a pelleted alfalfa diet at two levels of intake. Disappearances of individual EAA across the region of the small intestine drained by the mesenteric arcade (jejunum to ileum) were similar to those across the whole of the small intestine (duodenum to ileum). The net MDV flux of each EAA was similar to its rate of disappearance, but, with the exception of threonine on the low intake level, the net PDV flux was lower (P < .05). Increasing the intake of alfalfa from 800 to 1,200 g/d increased the rate of disappearance of individual EAA between the duodenum and ileum by .56 (range .43 to .65) and between the jejunum and ileum by .51 (range .45 to .60). The MDV and PDV blood flows increased by .35 and .39, respectively, and, with the exception of valine, net fluxes of individual EAA increased by .39 (range .20 to .50) across the MDV and by .44 (range .21 to .71) across the PDV. When net fluxes across the MDV and PDV were measured simultaneously, the ratio of PDV: MDV flux for each EAA was less than (P < .05) unity (mean .61, range .55 to .69), even though all MDV blood enters the PDV, contributing approximately .45 of the total portal flow. This observation suggests that, in regions of the tract not drained by the MDV, extraction of arterial blood EAA for tissue and secretory protein synthesis must exceed the release of protein degradation products into the venous drainage. The results are discussed in terms of endogenous protein secretions into the lumen of the tract anterior to the small intestine.

Quantification of circulating peptides and assessment of peptide uptake across the gastrointestinal tract of sheep.

Gastrointestinal absorption of peptides was examined in sheep fed a forage-based diet. Peptide concentrations were determined in arterial, portal, and mesenteric blood and plasma by quantification of amino acid concentrations before and after acid hydrolysis of samples that had been first deproteinized then subjected to Sephadex G-15 gel-filtration to remove residual protein. In contrast to other studies of ruminants, peptide concentrations for individual amino acids were lower than for the corresponding free amino acids with peptide (expressed as a proportion of total nonprotein amino acid) representing not more than .25 to .3 of total amino acid. Peptide concentrations in arterial, mesenteric, and portal blood and plasma were similar, indicating that on this diet there was no net uptake of peptides from the small intestine (mesenteric-drained viscera, MDV) or the whole tract (portal-drained viscera, PDV). Increasing the intake of alfalfa pellets from 800 to 1,200 g/d, while increasing the absorption and net flux across the MDV and PDV of free amino acids, had no effect on peptide absorption. Preparation of blood and plasma samples for peptide analysis with methods used in studies in which substantial peptide absorption has been reported indicated no net MDV or PDV flux of peptide. Such conflicting data on the extent of gastrointestinal peptide flux are discussed in the context of methodological differences and the importance of diet and physiological state of the animal.

Amino acid use by the gastrointestinal tract of sheep given lucerne forage.

Essential amino acid (EAA) utilization by gastrointestinal tract (GIT) tissues has been investigated in sheep given 800 and 1,200 g/day lucerne pellets. Animals prepared with indwelling catheters into the aorta and the portal drained viscera plus cannulas into the small intestine were infused with mixed U-13C-labeled amino acid or (1-13C]leucine tracers into the jugular vein or directly into the small intestine. GIT sequestration of EAA from arterial and luminal AA pools was determined from tracer and tracee arterioportal concentration differences at both levels of intake. Proportional tracer 13C-labeled EAA extraction of the arterial supply, on first pass across the GIT during jugular infusion, ranged from 0.063 for histidine to 0.126 for leucine. Recovery of intestinally infused tracer 13C-EAA at the portal vein ranged from 0.61 for histidine to 0.83 for valine. These data were independent of intake. Calculated rates of tracee sequestration by GIT tissues represented 0.45-0.65 of whole body EAA flux, except for histidine, for which the values were much lower (0.25-0.32). With the exception of phenylalanine, more than 0.8 of the EAA used by the GIT was extracted from circulating blood, thus calling into question the theory that GIT tissues make preferential use of EAA during absorptive metabolism, restricting supply to peripheral tissues such as skeletal muscle (growth) or mammary glands (lactation). Instead the GIT seems to compete very successfully with these tissues for circulating blood EAA.

Effects of growth hormone and an antiserum to rat growth hormone on serum IGF-I and muscle protein synthesis and accretion in the rat.

Rats were injected twice daily for up to 10 days with GH or with a polyclonal antiserum to rat GH, commencing at 21-22 days of age. Administration of bovine or human GH (1mg/day) improved whole body growth rates by 22% and 29% respectively. Plantaris muscle mass was also increased, by 7 and 14% respectively. Anti-GH injected twice daily resulted in a 7% decrease in body weight at 4 days and a 10% reduction by 10 days. Similar decreases were observed in the total protein content of plantaris and soleus muscles. The decrease in the fractional rate of protein synthesis was proportionately greater than the decline in protein content in plantaris muscle whereas in the soleus no change in the rate of protein synthesis was observed, suggesting that the effect on this muscle was due to an increase in the rate of protein degradation. Serum total IGF-I was unchanged by treatment with either GH or anti-GH while the amount of hepatic IGF-I mRNA was also unaffected by anti-GH injection. These data are consistent with a direct effect of GH or an effect mediated by an autocrine/paracrine mechanism of action on muscle but do not support a role for serum total IGF-I as an endocrine mediator of GH action.

Fate of the antinutritive proteins of soyabean in the ovine gut.

Defatted raw soyabean flour was administered intraruminally at a level of 10 g/kg body weight to a sheep fitted with ruminal, duodenal, and ileal cannulas. Soyabean lectin and trypsin inhibitor appeared in the duodenum within one hour, both reached the terminal ileum and disappeared within 24 hours. The passage of the lectin along the gut progressively lagged behind that of the inhibitor, which indicates that the lectin binds to the intestinal surface. The effect of the inhibitors was neutralized by a marked pancreatic hypersecretion. Contrary to earlier assumptions, the antinutritional proteins were not effectively degraded in the forestomachs.

Influence of protein nutrition on the response of growing lambs to exogenous bovine growth hormone.

Interactions between protein supply and the anabolic response to exogenous bovine (b) GH have been examined in two experiments using 28-35 kg lambs sustained entirely by intragastric infusion of volatile fatty acids (700 kJ/kg W 0.75 per day) into the rumen and the casein (600 mg (low protein; LP) or 1200 mg (high protein; HP)/kg W 0.75 per day) into the abomasum. Sheep received continuous i.v. infusions of bGH for 6 days in experiment 1 and for 18 days in experiment 2. Nitrogen balances were determined daily throughout both experiments and blood samples, from indwelling catheters, were assayed for GH, insulin-like growth factor-I (IGF-I), insulin and glucose. Infusion of bGH increased plasma GH concentration by five- to sixfold in all animals. There was an increase in N retention in both HP and LP animals over the first 2-3 days of GH administration. HP animals sustained higher N retentions (31%; P less than 0.05) throughout the GH administration but LP animals did not. In contrast, plasma IGF-I concentrations increased progressively over the first 72 to 96 h of GH administration in all sheep and thereafter remained significantly (P less than 0.05) elevated until termination of the GH infusion. In lambs which received both HP and LP infusion in experiment 1 the increase in IGF-I and LP infusions in experiment 1 the increase in IGF-I concentration by day 6 of GH administration was significantly (P less than 0.05) greater when they received the higher protein intake.(ABSTRACT TRUNCATED AT 250 WORDS)

The measurement of insulin-like growth factor 1 in sheep plasma.

A method is described for the radioimmunoassay (RIA) of insulin-like growth factor 1 (IGF-1) in neutralised formic acid-ethanol extracts of sheep plasma. The ability of the acid-ethanol pretreatment to remove the IGF-1 binding proteins (BPs), which interfere in the assay has been examined. Comparative plasma IGF-1 concentrations determined by the method correlated closely (P less than 0.001) with corresponding values where BPs were removed by acid gel filtration. The method has been applied to studies in which sheep were given exogenous growth hormone and indicated that plasma IGF-1 levels respond rapidly to the onset and termination of treatment.

Reduced cyclic myopia with pilocarpine gel.

Pilocarpine 4% gel and pilocarpine 4% solution were compared in young normal subjects for their effects on induced myopia. The pilocarpine 4% solution produced marked myopia lasting one to two hours which indicates that a qid therapeutic regimen produces about three to six hours of blurred vision during waking hours. The gel-induced myopic effects returned to normal in most subjects nine hours after a single instillation. Thus, pilocarpine-gel-induced myopic effects occur principally while asleep and are reduced substantially upon awakening. This allows patients to carry on normal activities throughout the day.

Measurement of volatile fatty acid production rates in sheep given roughage.

Measurement of the irreversible loss rate (ILR) of acetate, propionate and butyrate by radioisotope dilution of the respective tracers in sheep offered chopped dried grass from continuous belt type feeders gave 'plateau samples', the specific radioactivity of which had unacceptably high variance (coefficient of variation [cv] of the five or six samples taken from any one animal over the last four hours of 10 hours infusion ranged from 16 to 57 per cent). In an experiment which attempted to identify the source of this variability the distribution of the liquid phase marker 51Cr EDTA into different areas of the rumen was examined during its administration either in liquid form or impregnated on paper. The paper provided better mixing but incurred considerable spillage problems which would be unacceptable where calculations of ILR were required. Radiographic observations were made to examine the mixing of radio-opaque liquid and solid phase markers in the rumen. A better mixing of both was achieved with intermittent than continuous feeding. When 1-14C- and 2-14C-labelled acetate were each infused into the rumen of four sheep given two levels of chopped dried grass by means of hourly feeders, samples of rumen liquor gave much lower variability of the mean plateau specific radioactivity values than was obtained in experiment 1 (cv less than 15 per cent in all but one sheep). The ILRs of acetate and the transfer quotients of carbon from acetate to butyrate obtained using 1-14C- and 2-14C-labelled acetate were similar.(ABSTRACT TRUNCATED AT 250 WORDS)

Microbial protein synthesis in cattle given roughage-concentrate and all-concentrate diets: the use of 2,6-diaminopimelic acid, 2-aminoethylphosphonic acid and 35S as markers.

Three steers, each fitted with a rumen cannula and a re-entrant cannula in the proximal duodenum, were offered diets consisting of a barley-based concentrate and chopped hay at a daily intake of 61 g/kg live weight0.75 given in three equal meals. The ratio, concentrate: hay was changed from 50:50 to 90:10 and then to 100:0 in successive periods of 12-18 weeks and the flow and composition of digesta at the duodenum was measured over 48-h periods on each dietary treatment. Samples of bacteria and protozoa were separated from rumen contents and the proportions of bacterial and protozoal nitrogen (N) in duodenal digesta were estimated using 2,6-diaminopimelic acid (DAPA) and 2-aminoethylphosphonic acid (AEP) as markers. On separate occasions, radioactive sulphur (35S) was infused into the rumen for 48 h and digesta collected over the final 24 h; the specific radioactivity of S in microbial and digesta fractions was used to estimate the proportions of microbial N. 35S gave reproducible and apparently reliable estimates of microbial protein formation: the proportion of microbial N in digesta was significantly higher (P less than 0.05) for the 50:50 diet than for the other treatments but the energetic efficiency of microbial protein formation did not differ significantly between diets. Estimates of bacterial N based on DAPA concentrations were highly variable and frequently impossibly high. It is suggested that many of the anomalous values were the result of non-representative sampling of the rumen microbial population and that this is particularly likely to occur when conditions within the rumen are unstable. AEP was found to be unsuitable as a marker for rumen protozoa as considerable concentrations of this substance were found also in rumen bacteria.

Methane formation in faunated and ciliate-free cattle and its relationship with rumen volatile fatty acid proportions.

Twelve steers fitted with rumen cannulas were used in three separate experiments to investigate the effects of the presence or absence of rumen ciliate protozoa on methane production. The diet consisted of 850 g barley and 150 g protein supplement/kg, and was given in three feeds daily at a restricted level of 61 g/kg live weight 0.75. Animals were defaunated initially by allowing ad lib. consumption of this diet and were then maintained ciliate-free by isolation or were faunated by inoculation with a mixed ciliate suspension. Samples of rumen fluid were taken routinely for the assessment of microbial populations and for volatile fatty acid (VFA) analysis and energy and nitrogen balances and digestibility measurements were made at intervals while animals were confined in respiration chambers. In each experiment the rumen VFA proportions changed from a high-propionate pattern under ciliate-free conditions to a low-propionate, high-butyrate pattern in the presence of ciliates: differences between treatments were highly significant (P less than 0.001). There were also marked differences between treatments in CH4 production but a reliable comparison was possible only in Expt 3, in which CH4 was significantly higher (P less than 0.001) in the presence of a rumen ciliate population. In Expt 3 the increased loss of energy as CH4 in the faunated animals amounted to 4.8 MJ/100 MJ energy intake. Stoichiometric estimates of CH4 production derived from the observed VFA proportions showed good agreement with CH4 production as measured in respiration chambers. On average, the stoichiometric CH4 values overestimated CH4 production by a factor of 1.08. Highly significant linear relationships (P less than 0.001) were observed between the molar proportion of each major VFA and the quantity of CH4 produced: the proportion of propionic acid was inversely related to CH4 and showed the lowest residual standard deviation of all the relationships examined. The losses of energy in faeces and urine did not differ between treatments hence the increased loss of energy as CH4 in the faunated animals resulted in a significant reduction in the metabolizability of the diet from 0.73 to 0.69 (P less than 0.05). No significant differences were detected between treatments in heat production, apparent digestibility coefficients or N balance. It is suggested that the rumen ciliates, by modifying the rumen VFA proportions, are directly responsible for the increased CH4 production in faunated animals.

2-Aminoethylphosphonic acid concentrations in some rumen ciliate protozoa.

The concentration of 2-aminoethylphosphonic acid has been measured in seven genera of rumen ciliate protozoa. Expressed as milligrams per gram of total nitrogen, 2-aminoethylphosphonic acid concentrations ranged from 17.2 in Ophryoscolex spp. to 72.4 in Eremoplastron spp.

Duration of effect of pilocarpine gel.

Thirty-five patients participated in a clinical trial of pilocarpine hydrochloride gel applied once daily at 10 PM. Patients tolerated the medication well and there were no untoward side effects. Significant lowering of intraocular pressure was found for 24 hours after administration. The effect 12 hours after administration was greater than 24 hours after administration. Therefore, pilocarpine gel can be endorsed as an effective medication for 24 hours in the vast majority of patients. However, it is incumbent on the prescribing ophthalmologist to measure the IOP at 10 PM at least once after prescribing pilocarpine gel to ensure adequate control of IOP at that time.