Prediction models of silage fermentation products on crop composition under strict anaerobic conditions: a meta-analysis.

A meta-analysis was conducted to establish linkages between crop and fermentation variables. Data from well-controlled mini silage studies were used in which no additives had been used and no ingress of air had occurred. The silage set consisted of data on crop chemical composition and epiphytic lactic acid bacteria count, and fermentation products (organic acids, alcohols, and ammonia-N) from 118 silages made from 30 grass, 7 legume, 15 grass and legume mixtures, and 66 whole-crop maize samples. The prediction models for fermentation products on crop variables were obtained by stepwise multiple regression analysis. Perennial forage and maize silages were analyzed separately. The best models were obtained for acetic acid in perennial forage silages, with a coefficient of determination of 0.63, and for lactic acid and ethanol in whole-crop maize silages, with coefficients of determination of 0.84 and 0.61, respectively. Fermentation products of perennial forage and maize silages were best related to dry matter and crude protein contents, respectively. Overall, the prediction equations were weak.

Degradation of two soluble proteins--casein and egg protein by a macro in vitro method.

Degradation of casein and egg protein was studied with whole rumen contents (RC) in a macro in vitro system to elucidate previous findings of initial rapid disappearance of soluble proteins in vitro. Five to 7.5 kg of RC from a dry and/or a lactating cow were incubated with buffer and casein or egg protein for 180 min with frequent sampling. Degradation was measured as loss of trichloroacetic acid precipitable N (TCA-N) from the inocula. Normal (39°C) and low (2°C) temperature incubations were examined in Exp. 1, using 1 g of TCA-N from casein. Four levels of casein (0-12 g TCA-N) in Exp. 2 and four levels of egg albumin (0-24 g TCA-N) in Exp. 3 were fermented at 39°C. Initial recovery of casein TCA-N was 106% at 2°C and 56% at 39°C (Exp. 1). Casein (TCA-N) recovered initially increased in Exp. 2 from 21% at 3 g to 86% at 12 g TCA-N, while absolute loss remained relatively constant at 358 mg TCA-N/kg RC (SD=47). Fractional degradation rate was highest (0.03/min) at the intermediate dosage level. In the absence of rumen fluid (Exp. 4), no casein was lost. Initial egg protein recovery was on average 103% (Exp. 3). Recovery seemed unaffected by dosage level, and absolute degradation rate was relatively constant over time and increased with dosage level (p<0.001) from 1.48 to 2.95 mg TCA-N/(kg RC × min). Maximum degradation rate [mg TCA-N/(kg RC × min)] and affinity constant (mg TCA-N/kg RC) were estimated at 261 and 1650, respectively. It is concluded that a surprisingly constant amount of casein disappears immediately from warm rumen fluid and that this does not occur either with chilled RC, in the absence of rumen fluid, or when replaced with egg protein. The mechanisms for this disappearance are yet to be discovered.

Using a novel macro in vitro technique to estimate differences in absorption rates of volatile fatty acids in the rumen.

A novel macro in vitro system was used to test the theory that rumen proportions of acetate, propionate and butyrate are not representative of their respective net production rates. Whole rumen content (10-16 kg) from two cows was mixed with a bicarbonate buffer and incubated separately in two 40-l in vitro vessels for 3 h. A total of six experimental periods were used. In this study, a total of six cows were used and fed 1/8 of the daily ration by hand every 3 h. To obtain differences in rumen volatile fatty acids (VFA) composition, 1 l of acetate (416 mm), propionate (108 mm), butyrate (79 mm), lactic acid (300 mm) or nothing was infused during 24 h into the rumen before collection of representative samples of rumen contents. Infusions of acids were then continued during the in vitro incubations in exact proportion to the digesta removed from the rumen. In Periods 1 and 2, the cows were alternatively infused with acetate or nothing. In Periods 3 and 4, the infusions consisted of propionate or butyrate and in Periods 5 and 6 of lactate or nothing. Nine liquid samples were obtained between 3 and 180 min after the start of incubation and analysed for concentrations of VFA. Changes in proportions of individual VFA were estimated by linear regression. No differences in VFA proportions were observed in the absence of infusion (p> 0.5) over time, but when individual VFA were infused, their respective proportions increased. This was interpreted as the result of a decreased in vitro fermentation rate of digesta substrates compared with that in the rumen. Lactate infusion increased butyrate proportion in vitro. It is concluded that this study could not provide any evidence that ruminal VFA proportions are unrepresentative of the proportions of net production.

The effect of atazanavir and atazanavir/ritonavir on UDP-glucuronosyltransferase using lamotrigine as a phenotypic probe.

Atazanavir (ATV) is known to inhibit UGT1A1-mediated glucuronidation. Here we report the effect of ATV and ATV/ritonavir (RTV) on another UGT1A isoenzyme, UGT1A4. Twenty-one healthy volunteers received a single dose of 100 mg of oral lamotrigine on days 1, 13, and 27; on each occasion blood was sampled before the dose was administered and through 120 h after ingestion of the drug. On days 8-17 the subjects received oral ATV 400 mg q.d. On days 18-30 the subjects received oral ATV 300 mg plus oral RTV 100 mg q.d. Seventeen subjects were evaluable for pharmacokinetic analysis. Geometric mean ratios (+90% confidence intervals (CIs)) of lamotrigine area under the plasma concentration-time curve (AUC)(0-inf) and peak plasma concentration (C(max)) for ATV + lamotrigine and for lamotrigine alone were 0.88 (0.86-0.91) and 0.99 (0.95-1.02), respectively; the corresponding ratios for ATV/RTV and for lamotrigine were 0.68 (0.65-0.70) and 0.94 (0.90-0.97), respectively. The mean ratio of lamotrigine-2N-glucuronide to lamotrigine AUC(0-inf) increased from 0.45 for lamotrigine to 0.71 for ATV/RTV + lamotrigine. ATV alone does not significantly influence glucuronidation of lamotrigine. In contrast, ATV/RTV results in moderately decreased exposure to lamotrigine.

Sources of variation in rates of in vitro ruminal protein degradation.

Rates and extents of ruminal protein degradation for casein, solvent soybean meal (SSBM), expeller soybean meal (ESBM), and alfalfa hay were estimated from net appearance of NH3 and total amino acids in in vitro media containing 1 mM hydrazine and 30 mg/L of chloramphenicol. Protein was added at 0.13 mg of N/mL of medium, and incubations were conducted for 4 to 6 h, usually with hourly sampling. Inocula were obtained from ruminally cannulated donor cows fed diets of grass silage or alfalfa and corn silages plus concentrates. Preincubation or dialysis of inocula was used to suppress background NH3 and total amino acids; however, preincubation yielded more rapid degradation rates for casein and SSBM and was used in subsequent incubations. Preincubation with added vitamins, VFA, hemin, or N did not alter protein degradation. Protein degradation rates estimated for SSBM, ESBM, and alfalfa were not different when computed from total N release or N release in NH3 plus total amino acids, regardless of whether amino acids were quantified using ninhydrin colorimetry or o-phthalaldehyde fluorescence. Accounting for the release of peptide-N also did not affect estimated degradation. However, casein degradation rates were more rapid when using total N release or accounting for peptide-N, indicating significant accumulation of small peptides during its breakdown. Rates also were more rapid with inocula from lactating cows versus nonlactating cows with lower feed intake. Protein degradation rates were different due to time after feeding: casein rate was more rapid, but SSBM and ESBM rates were slower with inocula obtained after feeding. Several characteristics of ruminal inoculum that influenced breakdown of the rapidly degraded protein casein did not appear to have direct effects on degradation of protein in soybean meal.

Tumorigenesis, metabolism, speciation, bioavailability, and tissue deposition of selenium in selenium-enriched ramps (Allium tricoccum).

Ramps (Allium tricoccum) were grown either in a mixture of vermiculite and peat moss or hydroponically with various concentrations of selenium as sodium selenate. The concentrations used were from 30 to 300 mg of selenium/kg of vermiculite-peat moss or from 10 to 120 mg/L in the hydroponic solutions. Levels as high as 784 mg of selenium/kg were obtained in the ramp bulbs when grown with high levels of selenium in the vermiculite-peat moss, and up to 600 mg of selenium/kg was obtained hydroponically. The predominant form of selenium in the ramp bulbs at all concentrations of selenium was Se-methylselenocysteine, with lower amounts of selenate, Se-cystathionine, and glutamyl-Se-methylselenocysteine. There was a approximately 43% reduction in chemically induced mammary tumors when rats were fed a diet with Se-enriched ramps. Dietary Se-enriched ramps for rats did not result in excessive tissue selenium accumulation or undesirable side effects. Bioavailability studies with rats indicated that selenium in ramps was 15-28% more available for regeneration of glutathione peroxidase activity than inorganic selenium as selenite. Therefore, Se-enriched ramps appear to have potential for the reduction of cancer in humans.

Selenium speciation in enriched and natural samples by HPLC-ICP-MS and HPLC-ESI-MS with perfluorinated carboxylic acid ion-pairing agents.

Selenium-enriched plants, such as hyperaccumulative phytoremediation plants (Astragalus praleongus, 517 micrograms g-1 Se, and Brassica juncea, 138 micrograms g-1 Se in dry sample), yeast (1200, 1922 and 2100, micrograms g-1 Se in dry sample), ramp (Allium tricoccum, 48, 77, 230, 252, 405 and 524 micrograms g-1 Se in dry sample), onion (Allium cepa, 96 and 140 micrograms g-1 Se in dry sample) and garlic (Allium sativum, 68, 112, 135, 296, 1355 micrograms g-1 Se in dry sample) were analyzed by HPLC-ICP-MS for their selenium content and speciation after hot water and enzymatic extractions. Reference samples with natural selenium levels, such as onion and garlic controls, cooking garlic powder, baking yeast powder and a commercial garlic supplement were also analyzed. Selected samples were also examined by HPLC-electrospray ionization (ESI)-MS. HPLC was mostly carried out with 0.1% heptafluorobutanoic acid (HFBA) as ion-pairing agent in 1 + 99 v/v methanol-water solution, but 0.1% trifluoroacetic acid (TFA) in 1 + 99 v/v methanol-water solution was also utilized to permit chromatography for compounds that did not elute with HFBA. More than 75% of the total eluting selenium compounds, based upon element specific detection, were identified from retention time data and standard spiking experiments, and between 60 and 85% of compounds were identified by MS, with up to 25% of the total eluting molecular selenium species being unidentified as yet. Limits of quantification (LOQ, defined as the concentration giving an S/N of 10) for HPLC-ICP-MS were in the range 2-50 ng mL-1 Se in the injected extracts for the selenium-enriched samples and 2-10 ng mL-1 Se for the natural selenium level samples. LOQ values for HPLC-ESI-MS were ca. 100 times higher than those measured by HPLC-ICP-MS.

Chemical speciation influences comparative activity of selenium-enriched garlic and yeast in mammary cancer prevention.

A recent human intervention trial showed that daily supplementation with selenized yeast (Se-yeast) led to a decrease in the overall cancer morbidity and mortality by nearly 50%; past research has also demonstrated that selenized garlic (Se-garlic) is very effective in mammary cancer chemoprevention in the rat model. The goal of this study was to compare certain biological activities of Se-garlic and Se-yeast and to elucidate the differences based on the chemical forms of selenium found in these two natural products. Characterization of organic selenium compounds in yeast (1922 microg/g Se) and garlic (296 microg/g Se) was carried out by high-performance liquid chromatography with inductively coupled plasma mass spectrometry or with electrospray mass spectrometry. Analytical speciation studies showed that the bulk of the selenium in Se-garlic and Se-yeast is in the form of gamma-glutamyl-Se-methylselenocysteine (73%) and selenomethionine (85%), respectively. The above methodology has the sensitivity and capability to account for >90% of total selenium. In the rat feeding studies, supplementation of Se-garlic in the diet at different levels consistently caused a lower total tissue selenium accumulation when compared to Se-yeast. On the other hand, Se-garlic was significantly more effective in suppressing the development of premalignant lesions and the formation of adenocarcinomas in the mammary gland of carcinogen-treated rats. Given the present finding on the identity of selenomethionine and gamma-glutamyl-Se-methylselenocysteine as the major form of selenium in Se-yeast and Se-garlic, respectively, the metabolism of these two compounds is discussed in an attempt to elucidate how their disposition in tissues might account for the differences in cancer chemopreventive activity.

High-performance liquid chromatography of selenium compounds utilizing perfluorinated carboxylic acid ion-pairing agents and inductively coupled plasma and electrospray ionization mass spectrometric detection.

Increasing speciation demands in clinical chemistry, toxicology and nutrition have made the determination of the total elements in a sample inadequate; the amount of an element and the chemical forms in which it is present need to be known. Inductively coupled plasma mass spectrometry (ICP-MS) was used after high-performance liquid chromatographic (HPLC) separation, as was electrospray ionization mass spectrometry (ESI-MS). The effect of variation of the number of carbon atoms in perfluorinated carboxylic acids used as ion-pairing agents for the separation of selenium compounds was examined. Trifluoroacetic acid (0.1%), pentafluoropropanoic acid (0.1%) or heptafluorobutanoic acid (0.1%; HFBA) were alternatively used as additives to methanol-water (1:99, v/v) solutions as mobile phases. Reversed-phase HPLC-ICP-MS with 0.1% HFBA in the mobile phase allowed more than 20 selenium compounds to be separated in 70 min in an isocratic elution mode; the separation of natural selenium-enriched sample extracts was examined and explained. The pH of the 0.1% HFBA solution was modified with hydrochloric acid or ammonia and the pH of the sample extracts before injection was modified in order to overcome unwanted double peak formation in the chromatograms of sample extracts. Oxidations of standard gamma-glutamyl-Se-methylselenocysteine and Se-methylselenocysteine were carried out using 30% H2O2 solution and identifications of selenium-containing oxidation products were made using HPLC-ICP-MS and HPLC-ESI-MS. The principal organic oxidation product in both cases was methaneseleninic acid (MeSeO2H).

Optimization and evaluation of atomic emission gas chromatographic detection for nitrogen using the 388 nm molecular emission spectral band.

Nitrogen determination by gas chromatography with atomic emission (microwave-induced plasma) detection (GC-AED) has been accomplished using the 174 nm atomic emission line, but with very limited selectivity and sensitivity. Nitrogen can also be detected using the cyanogen (CN) molecular band at 388 nm. A commercial GC-AED system was modified to allow the use of the 388 nm line for nitrogen detection, giving an improvement of 100-fold in sensitivity and selectivity, when compared with the 174 nm mode. Limits of detection of 10 pg/s were common, representing a 10-fold improvement. Compound-independent behavior was found for the system, working with optimum operating conditions, while instrumental problems were clearly reflected by a drastic compound dependent behavior. Response factors showed an important dependency upon the concentration of the element present. This dependency affected the accuracy of the determination of empirical formulae using GC-AED.

Determination of trace elements in marine plankton by inductively coupled plasma mass spectrometry (ICP-MS).

A method has been developed for the determination of 23 elements in marine plankton in which inductively coupled plasma (ICP) source mass spectrometry (MS) was used to quantify the elements in the solution after digestion in a mixture of hydrofluoric and nitric acids in sealed PTFE vessels in a microwave field. The procedure was validated by the analysis of a standard reference soil (SRM 2709 San Joaquin Soil) and a standard reference fresh water plankton (CRM 414). The method was applied to the analysis of several marine plankton samples grown under controlled conditions including several whose growth media had been enriched with selenium. Matrix induced signal suppressions and instrumental drift were corrected by internal standardization. The suitabilities of germanium, indium, rhodium, scandium and yttrium as internal standard elements were evaluated. Neither scandium nor yttrium could be used due to the presence of these elements in the samples, germanium was used for the determination of As, Co, Cu, Fe, Ni, Se, Si and Zn, indium was used for Al, Ba, Ca, Eu, Sr, and Tl, and rhodium was used for Cd, Cr, Hg, Mg, Pb, Sb, Sn, and V. For Al, Ca, Cr, Cu, Fe, Mg, Mn, Ni, Si, Sr, V, and Zn internal standardization did not completely compensate for the suppressive effect of the heavier elements and the solutions were diluted. However, for As, Ba, Cd, Co, Eu, Hg, Pb, Sb, Se, Sn and T1, it was possible to obtain accurate results despite the 35-40% suppression in the signals. Isobaric overlap was only a problem in the cases of 42Ca and 78Se; 44Ca and 77Se, respectively, were used. Memory effects were only observed with Hg for which a nitric acid-sodium chloride solution was the most effective wash-out solution. The marine plankton samples were able to tolerate a higher concentration of Hg as the selenium concentration increased.

Oxalogenesis in parenteral nutrition solution components.

Oxalate has been implicated in the etiology of nephrocalcinosis in premature infants as well as in the formation of insoluble precipitates in total parenteral nutrition (TPN) intravenous tubing. Oxidation of ascorbate to oxalate, especially in the presence of catalysts such as copper and iron, has been implicated in formation of these precipitates. The purpose of this project was to measure oxalate formation in certain TPN components separately and in combination. Neonatal TPN solution components in combination were infused at 5 mL/h under simulated clinical conditions used in a neonatal intensive care unit. Aliquots were assayed at intervals for oxalate by capillary electrophoresis. Oxalate is present in one TPN mixture at concentrations up to 8 ppm. The addition of ascorbate to an aqueous solution of trace metals may promote oxalogenesis.

High-performance liquid chromatography of selenoamino acids and organo selenium compounds. Speciation by inductively coupled plasma mass spectrometry.

As part of an ongoing study to identify selenium compounds with cancer chemopreventive activity, extracts of selenium-enriched samples were analyzed by HPLC-inductively coupled plasma (ICP)-MS. Ion-exchange, ion pair and derivatization methods for reversed-phase HPLC were considered and advantages and disadvantages for each compared. Anion exchange allows separation of selenite and selenate, but otherwise provides poor separation. Pre-column derivatization and reversed-phase chromatography provides separation of compounds with terminal amine functionalities, but many other species elute in the void volume. The ion pair method gave optimal separation and was compatible with standard ICP-MS operating conditions.

Development, validation, and application of a method for quantification of methylmercury in biological marine materials using gas chromatography atomic emission detection.

A gas chromatographic method was developed for the quantification of alkylmercury species using microwave-induced plasma atomic emission detection (GC-AED). The column conditioning and analyte derivatization required for previous methods were found to be unnecessary for stable, accurate, and sensitive element-specific detection using GC-AED. Chromatographic and detection parameters such as stationary phase type, stationary phase film thickness, GC column dimensions, helium mobile phase column head pressure, detector makeup gas flow rate, and detector reagent gas type and flow rate were found to significantly affect analyte response. The detection limit for the optimized GC-AED conditions was 0.8 pg (0.1 pg/s) of methylmercury chloride (as mercury). A solid-liquid extraction procedure with preparative gel permeation chromatography cleanup and GC-AED analysis was used to quantify methylmercury in a variety of complex matrix marine materials. The methylmercury quantification method was validated with four marine certified reference materials (CRMs). The method was then applied to 13 standard reference materials, CRMs, and control materials for which no certified reference values for methylmercury have been determined. Four National Institute of Standards and Technology Standard Reference Materials and one control material, which were analyzed using the GC-AED method, were also analyzed by two other laboratories using independent methods to further validate the method.

CT of a parathyroid lipoadenoma. Case report.

A 54-year-old woman with primary hyperparathyroidism underwent parathyroid exploration following negative ultrasonography, CT and 99Tc-201Tl scintigraphy. A 2 x 1.5 x 1-cm large mass dorsal to the midportion of the left thyroid lobe was extirpated and a hyperfunctional lipoadenoma containing 70% or more of fatty tissue was verified microscopically. Retrospective evaluation of CT revealed a well demarcated lipomatous mass with a homogeneous density similar to that of subcutaneous fat corresponding to the surgical finding.

Fibrin adhesive in radical mastectomy.

OBJECTIVE: To find out if fibrin adhesive glue applied locally would reduce the incidence of seroma after modified radical mastectomy for breast cancer. DESIGN: Prospective randomised study. SETTING: City hospital, Sweden. SUBJECTS: 68 women undergoing modified radical mastectomy with axillary clearance for breast cancer. MAIN OUTCOME MEASURES: Amount of postoperative drainage, number of seromas aspirated volumes; length of hospital stay, influence of surgeon operating. RESULTS: Seromas developed in a total of 40/68 patients (59%), 23/36 in the fibrin adhesive group (64%) and 17/32 in the control group (53%); p = 0.5 (95% confidence interval of the difference--0.13 to 0.34). There were no significant differences in the volume of aspirations or in hospital stay. The skill of the surgeon influenced the incidence of seromas, but the differences were not significant (p = 0.5). CONCLUSION: Local application of a fibrin adhesive glue has no effect on the incidence of seroma formation after modified radical mastectomy.

Set-point for parathyroid hormone release increases with postmaturational aging in the rat.

The plasma concentration of immunoreactive PTH (iPTH) increases with postmaturational aging in both humans and animals. In the present study we determined the basal, maximally stimulated, and maximally suppressed levels of iPTH and the concentration of whole blood ionized calcium sufficient to produce half-maximal suppression of the plasma concentration of iPTH (set-point for PTH release) in male Fischer 344 rats aged 3, 6, 12, 18, 24, and 28 months. Basal iPTH increased 2.3-fold from 3 to 28 months of age, whereas basal blood ionized calcium remained unchanged. The set-point for PTH release increased steadily and significantly (P < 0.001) from 1.19 +/- 0.09 mM at 3 months to 1.37 +/- 0.13 mM at 24 months and then declined slightly to 1.32 +/- 0.11 mM at 28 months of age. Basal iPTH correlated significantly with set-point. Neither maximally stimulated nor maximally suppressed iPTH levels showed any significant change with advancing age. These results suggest that the age-related increase in basal plasma iPTH in the rat may be in part a consequence of an increase in the set-point for PTH release.

Unilateral neck exploration for primary hyperparathyroidism: analysis of a controversy using a mathematical model.

Most endocrine surgeons explore both sides of the neck and identify all parathyroid glands when operating on patients with primary hyperparathyroidism. Others, however, advocate the unilateral approach, i.e., if an adenoma and a normal gland are identified, the contralateral side is not explored. We analyzed the strategy of the unilateral approach using a mathematical model to determine the variables that influence the probability of missing a tumor on the unexplored side of the neck. Assuming the frequency of single adenoma is 80%, hyperplasia 14%, double adenomas 4%, triple adenomas 1%, and carcinoma 1%, and the probability of missing a tumor on the explored side is 5%, we found that: 1. Only 41% of the patients treated by the unilateral approach undergo unilateral exploration. This is increased to 62% when a localization study with a sensitivity of 80% is used pre-operatively. 2. The probability of missing a tumor on the unexplored side of the neck parallels the prevalence of multiple adenomas. Half of the patients with triple adenomas and two-thirds of the patients with double adenomas will have a missed tumor when treated by the unilateral approach. 3. Patients who undergo unilateral exploration have an additional 7% to 8% probability of missing a tumor that would have been found if bilateral exploration is performed. This risk is lowered to 2% by a pre-operative localization study that is 80% sensitive. 4. A prospective study will require 684 patients, randomized to the unilateral or bilateral approach, to have an 80% statistical power (alpha = 0.05, beta = 0.20) of detecting a difference between a 5% and a 10% risk of missing a tumor.

Primary hyperparathyroidism in younger and older patients: symptoms and outcome of surgery.

Two-hundred and fifty patients undergoing initial exploration for primary hyperparathyroidism were analyzed for differences in clinical presentation, biochemical status, pathology, and outcome of surgery. In patients less than 60 years of age (younger patients, n = 119) the most common preoperative symptoms and signs were fatigue (40.3%), bone pain (33.6%), renal stones (31.0%), hypertension (27.7%), and psychiatric illness (27.7%). In patients greater than or equal to 60 years of age (older patients, n = 131) the most frequent symptoms and signs were hypertension (46.6%), fatigue (35.1%), bone pain (30.5%), muscle weakness (28.2%), and joint pain (22.9%). Renal stones were 2.6 times more common (p less than 0.001, chi 2) in younger patients and hypertension 1.7 times more common (p less than 0.05, chi 2) in older patients. There was no significant difference in the preoperative and postoperative laboratory values typically associated with primary hyperparathyroidism. Double adenomas were more common in older (9.2%) than in younger patients (2.5%, p less than 0.05, chi 2). Surgical cure was obtained in 98.8% of patients, and after parathyroidectomy 83% of the younger and 82% of the older patients experienced substantial relief of pre-operative symptoms. Specific questioning revealed most patients to be symptomatic and older patients appear to receive the same clinical and metabolic benefits from parathyroidectomy as younger patients.