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.

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.

Adrenocortical carcinoma. A retrospective study of a rare tumor with a poor prognosis.

A retrospective study was performed on 54 patients diagnosed as having adrenocortical carcinoma during 1974-1983. The initial symptoms were often diffuse: abdominal pain, weight loss, or fever, and more than 60% of the patients showed no evidence of overproduction of hormone. The median tumor diameter was 13 cm and almost half of the tumors had metastasized at diagnosis. A radical tumor resection could be performed in less than 50% of the patients, and at histopathological re-examination some tumors were not conclusively verified as malignant. Capsular invasion, nuclear pleomorphism and mitoses were found more commonly in patients who succumbed to the disease. Seven of 29 patients treated with chemotherapy showed an objective response and two of them are still alive and free of disease. The overall 5-year-survival rate was 19%, compared with 45% for patients with radically resected tumors. Patients with no biochemical signs of overproduction of adrenocortical hormone appeared to have a better prognosis than those with hormone excess. Together with increased use of ultrasound and computed tomography, a urinary steroid profile might hopefully contribute to earlier discovery of these often clinically silent tumors. However, it remains to be determined whether these diagnostic improvements, together with more aggressive surgery and adrenolytic chemotherapy, can improve the poor prognosis.

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.

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).

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.

Impact of long-term relative bowel rest on conditions for colonic surgery.

Collagen content, bursting wall tension, and suture-holding capacity in the proximal and distal colon of the rat were studied after long-term treatment with a low-residue or a standard laboratory chow diet. Collagen content decreased uniformly in both the proximal and distal colon of the low-residue diet group. In addition, the bursting wall tension of the nonoperated proximal colon was reduced, whereas the breaking strength of a newly constructed anastomosis at three different colonic sites was unaffected.

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.

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.

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.

Adsorption and displacement effects in the gas-chromatography of metal beta-diketonates.

A detailed study of the gas chromatography of the aluminium(III), chromium(III) and iron(III) beta-diketonates has shown that their elution and separation characteristics arise from a number of adsorptive effects. Conditions of optimal peak shape for individual compounds are established by varying Chromatographie parameters, and the adsorption of one metal chelate on a column and its subsequent displacement by another chelate are investigated. The chromatography of iron(III) beta-diketonates is seen to be further complicated by gradual elution of a portion of the chelate before the rest of the sample.

Determination of chloride by displacement of hydrogen cyanide from mercury(II) cyanide.

A method, based on the passivity of mercury(II) cyanide in dilute sulphuric acid and its reaction with hydrochloric acid to produce hydrogen cyanide, has been developed for the determination of small amounts of chloride. Hydrogen cyanide, distilled from a mercury(II) cyanide-halide-dilute sulphuric acid system is found by iodometric measurement to be directly proportional to the amount of chloride or bromide and of hydrogen ion in acids such as sulphuric acid. A linear correlation also holds for iodide but the stoichiometry is different, the titration values being about three times larger than expected. By conversion of the cyanide into a dye by means of the pyridine-pyrazolone reagent, 0.014-0.43 mug ml chloride concentrations have been determined. The method is also applicable to bromide and sulphuric acid in small amounts but not to fluoride and iodide. Results are reproducible to within +/-2%.

Preparative gas chromatography of volatile metal compounds-I Separation of aluminium, chromium and iron beta-diketonates.

The analytical gas chromatography of a range of fluorinated and unfluorinated beta-diketonates of aluminium, chromium and iron has been studied m detail and conditions have been established for their complete separation; the complexes of trifluoroacetylpivaloylmethane show the best characteristics for this purpose. A range of liquid phases and column conditions have been considered and Apiezon substrates have been shown to give optimal resolution. The technique has been extended to a preparative scale with up to 0.1-g chelate samples, and the efficiency of the process demonstrated by the removal of 2% proportions of two metal complexes from a sample of the third. Implications of the technique for the purification of metals are discussed.

Biodeuteration of poly(beta-hydroxybutyrate).

The formation of poly(beta-hydroxybutyrate), PHB, by Rhodobacter sphaeroides and Alcaligenes eutrophus was studied using the following carbon sources and solvents: (1), acetate in H2O; (2), D3-acetate in H2O; (3), acetate in 90 to 92% D2O; and (4), D3-acetate in 90 to 92% D2O. The growth of Rb. sphaeroides cultured under condition (2) showed no apparent deuterium isotope effect, while considerably slowed growth in the presence of D2O was observed under conditions (3) and (4). In all cases, the PHB produced under deuterium enriched conditions was of high molecular weight. Interestingly, comparatively high volumetric formation of partially deuterated PHB was obtained using culture condition (4) for A. eutrophus. Fourier transform infrared spectroscopy (FT-i.r.), pyrolysis gas chromatography mass spectrometry (PGC-m.s.), and nuclear magnetic resonance (n.m.r.) were used to establish the extent and distribution of deuterium in the PHB samples produced. Partially deuterated PHB was obtained in each case, using a deuterium enriched culture. Considerable differences in the extent and distribution of deuterium were found between micro-organisms and culture conditions.

Investigations of the in situ bag technique and a comparison of the fermentation in heifers, sheep, ponies and rabbits.

Fiber fermentation using the in situ bag technique was studied in a hay-fed cow. Entry of fine particles into bags of varying pore size, the effect of sample size, rumen contractions, bag porosity and rumen contraction (bags suspended in vitro or in situ) and obstruction of liquid flow through the bag cloth were investigated (Exp. 1). In Exp. 2 fiber degradation in vitro and in situ with 5- and 37-micron pore size bags was measured utilizing six fistulated heifers (four large: 610 kg and two small: 243 kg), two sheep and two goats (30 kg), three ponies (130 kg) and four rabbits (3.2 kg). Degradation rate (k) and indigestible fiber (B) were determined after curve fitting. Lag of fermentation was also calculated. Results of Exp. 1 showed that plant fiber containing approximately 50% lignin and 2.9% N entered even 20-micron pores, that rumen contractions increased fiber disappearance and that obstructing liquid exchange limited fermentation. Results of Exp. 2 showed lower fiber residues for 37-micron than for 5-micron pore size bags and that in situ method, time and species were highly significant (P less than .0001). All model factors differed significantly among species (P less than .05), but not among the three methods. Lag approached significance for methods (P = .07), but not for species. In situ measurements (37-micron) resulted in the following values for k (h-1), B (%) and lag (h): large heifers .040, 39 and -1; small heifers .025, 39 and 0; sheep-goats .051, 42 and 2; ponies .030, 59 and -5 and rabbits .107, 85 and 3.

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.

Mortality in patients surgically treated for primary hyperparathyroidism due to solitary adenoma.

In a multicentre study including 5 surgical departments in Europe and USA the results of surgical treatment in primary hyperparathyroidism (HPT) due to single adenoma were analysed. At long term follow-up 60 out of 282 patients operated on for solitary parathyroid adenoma were found to be dead. The average age at operation was 69.2 years and the time of survival after surgery 3.9 years. The cumulative relative survival in patients aged 60-64 years was reduced by 18% (P less than 0.01) as compared to a control group corrected for nationality, age and gender. In patients above the age of 65 no such reduction could be demonstrated. The operative mortality was 1% and attributed to cardiac failures. Late mortality was caused by cardiovascular conditions in 52% and by malignant disease in 15%. None of these figures were statistically different from the age, gender and nation corrected control group. Among the miscellaneous causes of death were two patients who committed suicide during the first postoperative year. The results indicate that surgery for parathyroid adenoma can be performed with low morbidity and mortality.