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PubMed2006

Impact of upper digestive symptoms in patients with irritable bowel syndrome.

BACKGROUND: Functional digestive disorders constitute a sizable proportion of gastroenterology and primary healthcare consultations, and have a negative impact on health-related quality of life. Dyspepsia and heartburn are often associated with irritable bowel syndrome (IBS); however, the incidence of these symptoms and their effect on IBS patients have not been evaluated. AIM: To investigate the clinical, psychological and health-related quality of life impact of upper digestive symptoms on IBS patients. METHODS: A prospective, observational, multicentered study was conducted in Spain: 517 IBS patients (Rome II criteria), grouped according to predominant symptoms of constipation (IBS-C), diarrhea (IBS-D) or alternating bowel habit (IBS-A) and 84 controls without IBS were recruited. Upper digestive symptoms were recorded in a 30-day diary. Health-related quality of life was evaluated by Irritable Bowel Syndrome Quality of Life and Euro-Quality of Life Five-Dimension Questionnaires; psychological well-being was evaluated by the Psychological General Well-Being Index. RESULTS: IBS patients had greater frequencies of upper digestive symptoms (72.3 vs. 6.0%), dyspepsia (21.1 vs. 4.8%) and heartburn (40.0 vs. 13.1%) (all P < 0.05) than controls. Prevalence of upper digestive symptoms was lower in patients with IBS-D than in those with IBS-C or IBS-A (P < 0.05). Health-related quality of life and psychological status were significantly worse in IBS patients with upper digestive symptoms than in those without. CONCLUSIONS: Upper digestive symptoms, frequently present in IBS patients, impair health-related quality of life and psychological status. This effect is greater in patients with IBS-C and IBS-A than in those with IBS-D. These data emphasize the importance of evaluating the presence of upper digestive symptoms in IBS patients.

Adolescent↗
PubMed1995

Antihypertensive effect of thermolysin digest of dried bonito in spontaneously hypertensive rat.

1. The thermolysin digest of dried bonito, Katsuo-bushi, showed inhibitory activity (IC50 = 29 mu g/mL) for angiotensin I-converting enzyme (ACE) and an antihypertensive effect after a single oral administration in SHR at a dose of 500 mg/kg. In a long-term feeding experiment, in which 3 week old SHR were fed a standard chow supplemented with the digest for 7 weeks, elevation of the systolic blood pressure was significantly suppressed by 15 mg/kg per day of the digest. 2. A digest of dried bonito by gastrointestinal proteases (pepsin-trypsin-chymotrypsin) failed to lower the blood pressure after a single oral administration (1000 mg/kg) in spite of a fairly strong ACEI activity (IC50 = 41 mu g/mL). 3. The ACEI activity of the thermolysin digest did not change after preincubation with gastrointestinal proteases or ACE. However, that of the pepsin-trypsin-chymotrypsin digest was reduced after the preincubation with ACE suggesting that the apparent inhibitory activity was due to ACE substrate peptides. 4. Eight ACEI peptides were isolated from the thermolysin digest. Most of them were true inhibitors or precursors that are converted into true inhibitors by ACE or gastrointestinal proteases in vivo. The precursor type peptides required a longer time than true inhibitors to show maximal antihypertensive effect after a single oral administration in SHR. Thus, the thermolysin digest of dried bonito is a mixture of a true inhibitor and precursor peptides differing from each other in maximally effective times.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1983

Effect of soluble carbohydrates on digestion of cellulose by pure cultures of rumen bacteria.

The rate of cellulose digestion in the presence of either glucose or cellobiose was studied for the three predominant species of cellulolytic rumen bacteria: Ruminococcus albus, Ruminococcus flavefaciens, and Bacteroides succinogenes. When a soluble carbohydrate was added to cellulose broth, the lag phase of cellulose digestion was shortened. Presumably, this was due to greater numbers of bacteria, because increasing the size of the inoculum had a similar effect. Cellulose digestion occurred simultaneously with utilization of the soluble carbohydrate. The rate of cellulose digestion slowed markedly for B. succinogenes and R. flavefaciens and slowed less for R. albus after the cellobiose or glucose had been utilized, and was accompanied by a decrease in pH. Both the rate and the extent of cellulose digestion were partially inhibited when the initial pH of the medium was 6.3 or below. R. albus appeared to be less affected by a low-pH medium than were B. succinogenes and R. flavefaciens. When a soluble carbohydrate was added to the fermentation during the maximum-rate phase of cellulose digestion, the rate of cellulose digestion was not affected until after the soluble carbohydrate had been depleted and the pH had decreased markedly. Prolonged exposure of the bacteria to a low pH had little if any effect on their subsequent ability to digest cellulose. Cellulase activity of intact bacterial cells appeared to be constitutive in nature for these three species of rumen bacteria.

Animals↗
PubMed1990

Digestion of barley, maize, and wheat by selected species of ruminal bacteria.

Differences in the digestion of barley, maize, and wheat by three major ruminal starch-digesting bacterial species, Streptococcus bovis 26, Ruminobacter amylophilus 50, and Butyrivibrio fibrisolvens A38, were characterized. The rate of starch digestion in all cereal species was greater for S. bovis 26 than for R. amylophilus 50 or B. fibrisolvens A38. Starch digestion by S. bovis 26 was greater in wheat than in barley or maize, whereas starch digestion by R. amylophilus 50 was greater in barley than in maize or wheat. B. fibrisolvens A38 digested the starch in barley and maize to a similar extent but was virtually unable to digest the starch in wheat. The higher ammonia concentration in cultures of B. fibrisolvens A38 when grown on wheat than when grown on barley or maize suggests that B. fibrisolvens A38 utilized wheat protein rather than starch. Scanning electron microscopy revealed that B. fibrisolvens A38 initially colonized cell wall material, while S. bovis 26 randomly colonized the endosperm and R. amylophilus 50 preferentially colonized starch granules. There was subsequent colonization but only superficial digestion of wheat starch granules by B. fibrisolvens A38. Variation in the association between starch and protein within the endosperm of cereal grains contributes to the differential effectiveness with which amylolytic species can utilize cereal starch.

Journal Article↗
PubMed1980

Defect of in vitro digestive ability of polymorphonuclear leukocytes in paracoccidioidomycosis.

Selected functions of polymorphonuclear leukocytes were studied in patients with paracoccidioidomycosis (South American blastomycosis), in healthy control individuals, and in patients with diseases unrelated to paracoccidioidomycosis. Patients with paracoccidioidomycosis were also evaluated by standard immunological techniques. Phagocytosis and digestion of Paracoccidioides brasiliensis yeastlike cells in vitro was estimated by an original method. It was based on the appearance of phagocytosed P. brasiliensis in preparations stained by a modification of the Papanicolaou method and examined with phase-contrast optics. Interpretation of such findings was confirmed by electron microscopy. Two strains of P. brasiliensis were used. Strain 8506 was freshly isolated from a patient. Strain Pb9 was known to be nonpathogenic and to have a peculiar cell wall composition. Yeastlike cells of the Pb9 strain were digested significantly better than those of strain 8506. A higher number of leukocytes per fungus cells led to a higher proportion of digested P. brasiliensis. Leukocytes from patients with paracoccidioidomycosis phagocytosed the fungus in a normal way, but had a significant lower ability to digest it in vitro. When individual cases were analyzed, there was an excellent correlation between clinical evolution and digestive ability of polymorphonuclear leukocytes. There was good correlation between both of these and immunological parameters. Leukocytes from all groups behaved comparably in tests of general leukocyte function and in their abilities to kill and digest Candida albicans. Our results indicate that, as a group, polymorphonuclear leukocytes from patients with paracoccidioidomycosis had a significant, rather specific, defect in their in vitro digestive capacity against phagocytosed P. brasiliensis. There was also an inverse correlation between strain pathogenicity and its susceptibility to in vitro digestion by polymorphonuclear leukocytes. Our findings are concordant with and relevant to clinical reality.

Candida albicans↗
PubMed1993

Cereal grain digestion by selected strains of ruminal fungi.

The ruminal fungi Orpinomyces joyonii strain 19-2, Neocallimastix patriciarum strain 27, and Piromyces communis strain 22 were examined for their ability to digest cereal starch. All strains digested corn starch more readily than barley or wheat starch. Orpinomyces joyonii 19-2 exhibited the greatest propensity to digest starch in wheat and barley, whereas the digestion of these starches by N. patriciarum 27 and P. communis 22 was limited. Media ammonia concentrations were lower when fungal growth was evident, suggesting that all strains assimilate ammonia. Fungi formed extensive rhizoidal systems on the endosperm of corn, but O. joyonii 19-2 was the only strain to form such systems on the endosperm of wheat and barley. All strains penetrated the protein matrix of corn but did not penetrate starch granules. Starch granules from all three cereals were pitted, evidence of extensive digestion by extracellular amylases produced by O. joyonii 19-2. Similar pitting was observed on the surface of corn starch granules digested by N. patriciarum 27 and P. communis 22, but not on wheat and barley starch granules. The ability of ruminal fungi to digest cereal grains depends on both the strain of fungus and the type of grain. The extent to which fungi digest cereal grain in the rumen remains to be determined.

Ammonia↗
PubMed1987

Digestion of thyroglobulin with purified thyroid lysosomes: preferential release of iodoamino acids.

[131I]Thyroglobulin [( 131I]Tg), prepared by either enzymatic iodination of human goiter Tg in vitro or isolation from the thyroids of rats previously injected with 131I, was digested with a solubilized enzyme mixture prepared from purified hog thyroid lysosomes. The digestion was performed at 37 C for 24 h under nitrogen at pH 5.0 in the presence of 4 mM dithiothreitol. Under these conditions the release of free [131I] iodoamino acids (MIT, DIT, T4, and T3) was quantitatively very similar to that observed with a standard pronase digestion procedure. To determine whether other amino acids in Tg were released as quantitatively as the iodoamino acids, free amino acids in the lysosomal digest were measured, and total free amino acid release was compared with a similar analysis performed after digestion of [131I]Tg with 6 N HCl. Total amino acid release was much less complete than iodoamino acid release, indicating preferential release of iodoamino acids from Tg by lysosomal digestion. Analysis of the lysosomal digest by HPLC on a size exclusion column indicated that Tg was degraded to peptides with a mol wt less than 4000. Assuming that the in vitro lysosomal digestion system represents a valid model for the physiological proteolytic system that degrades Tg, the results of the present study suggest that a substantial portion of the Tg in the thyroid is not degraded to free amino acids and that peptide fragments of Tg are normally present in the thyroid. In such a case, the fate and possible physiological activity of these fragments require further elucidation.

Amino Acids↗
PubMed2005

Tracing heme in a living cell: hemoglobin degradation and heme traffic in digest cells of the cattle tick Boophilus microplus.

Heme is present in all cells, acting as a cofactor in essential metabolic pathways such as respiration and photosynthesis. Moreover, both heme and its degradation products, CO, iron and biliverdin, have been ascribed important signaling roles. However, limited knowledge is available on the intracellular pathways involved in the flux of heme between different cell compartments. The cattle tick Boophilus microplus ingests 100 times its own mass in blood. The digest cells of the midgut endocytose blood components and huge amounts of heme are released during hemoglobin digestion. Most of this heme is detoxified by accumulation into a specialized organelle, the hemosome. We followed the fate of hemoglobin and albumin in primary cultures of digest cells by incubation with hemoglobin and albumin labeled with rhodamine. Uptake of hemoglobin by digest cells was inhibited by unlabeled globin, suggesting the presence of receptor-mediated endocytosis. After endocytosis, hemoglobin was observed inside large digestive vesicles. Albumin was exclusively associated with a population of small acidic vesicles, and an excess of unlabeled albumin did not inhibit its uptake. The intracellular pathway of the heme moiety of hemoglobin was specifically monitored using Palladium-mesoporphyrin IX (Pd-mP) as a fluorescent heme analog. When pulse and chase experiments were performed using digest cells incubated with Pd-mP bound to globin (Pd-mP-globin), strong yellow fluorescence was found in large digestive vesicles 4 h after the pulse. By 8 h, the emission of Pd-mP was red-shifted and more evident in the cytoplasm, and at 12 h most of the fluorescence was concentrated inside the hemosomes and had turned green. After 48 h, the Pd-mP signal was exclusively found in hemosomes. In methanol, Pd-mP showed maximal emission at 550 nm, exhibiting a red-shift to 665 nm when bound to proteins in vitro. The red emission in the cytosol and at the boundary of hemosomes suggests the presence of heme-binding proteins, probably involved in transport of heme to the hemosome. The existence of an intracellular heme shuttle from the digestive vesicle to the hemosome acting as a detoxification mechanism should be regarded as a major adaptation of ticks to a blood-feeding way of life. To our knowledge, this is the first direct observation of intracellular transport of heme in a living eukaryotic cell. A similar approach, using Pd-mP fluorescence, could be applied to study heme intracellular metabolism in other cell types.

Adaptation, Physiological↗
PubMed2006

Effects of temperature and hydraulic retention time on anaerobic digestion of food waste.

A modified three-stage methane fermentation system was developed to digest food waste efficiently. This system consisted of three stages: semianaerobic hydrolysis, anaerobic acidogenesis and strictly anaerobic methanogenesis. In this study, we examined the effects of temperature and hydraulic retention time (HRT) on the methanogenesis. Operation temperature was adjusted from 30 degrees C to 55 degrees C, and the HRTs ranged from 8 to 12 d. The rate of soluble chemical oxygen demand (sCOD) removal correlated with digestion time according to the first-order kinetic model developed by Grau et al. [Water Res., 9, 637-642 (1975)]. With liquor food waste, thermophilic digesters showed a higher rate of sCOD removal than mesophilic digesters. The rates of biogas and methane production by thermophilic digesters were higher than those by mesophilic digesters regardless of HRT. Although maximum biogas production occurred when an HRT of 10 d was used, the methane yield was the highest in the reactor when an HRT of 12 d was used (223 l CH4/kg sCODdegraded). However, digestion stability decreased when an HRT of 8 d was used. The concentration of NH3-N generated in this experiment did not inhibit anaerobic digestion.

Bacteria, Anaerobic↗
PubMed2006

Methane production during storage of anaerobically digested municipal organic waste.

Anaerobic digestion of source-separated municipal organic waste is considered feasible in Denmark. The limited hydraulic retention in the biogas reactor (typically 15 d) does not allow full degradation of the organic waste. Storage of anaerobically digested municipal organic waste can therefore be a source of methane (CH4) emission that may contribute significantly to the potential global warming impact from the waste treatment system. This study provides a model for quantifying the CH4 production from stored co-digested municipal organic waste and estimates the production under typical Danish climatic conditions, thus quantifying the potential global warming impact from storage of the digested municipal organic waste before its use on agricultural land. Laboratory batch tests on CH4 production as well as temperature measurements in eight full-scale storage tanks provided data for developing a model estimating the CH4 production in storage tanks containing digested municipal organic waste. The temperatures measured in separate storage tanks on farms receiving digested slurry were linearly correlated with air temperature. In storage tanks receiving slurry directly from biogas reactors, significantly higher temperatures were measured due to the high temperatures of the effluent from the reactor. Storage tanks on Danish farms are typically emptied in April and have a constant inflow of digested material. During the warmest months the content of digested material is therefore low, which limits the yearly CH4 production from storage.

Anaerobiosis↗
PubMedDate not supplied

Laboratory-scale comparison of anaerobic-digestion alternatives.

Laboratory-scale digesters were used to perform side-by-side evaluations of alternative digestion systems including thermophilic-mesophilic-phased digestion (TPAD), acid/methane-phased digestion, mesophilic digestion, and the performance of the thermophilic stage of TPAD alone. Total detention times in the systems evaluated varied from 8 to 20 days. Temperatures in the mesophilic stage of TPAD were varied from 35 to 43.3 degrees C and temperatures in the thermophilic stage were varied from 55 to 58.9 degrees C. The purpose of the study was to evaluate volatile solids (VS) reduction and thickening properties of the different systems. Parameters evaluated included solids, volatile acids, gas production and quality, various chemical constituents of the sludge, and thickening properties using polymer and ferric chloride plus polymer. The TPAD systems were found capable of higher VS destruction at total detention times of 10 and 12.5 days compared to single-stage mesophilic or thermophilic digestion at 15 to 20 days. A laboratory-scale thickening test was performed to evaluate thickening properties. Based on obtaining 95% capture in the test, the polymer demand of mesophilic and acid-methane-phased digestion was the lowest. The TPAD system required approximately 180% of the dosage of the mesophilic sludge and thermophilic sludge required approximately 310% of the dosage. Temperatures of 40.5 and 43.3 degrees C in the mesophilic stage of TPAD were found to increase the polymer requirement and decrease the VS reduction of the TPAD system. Higher temperatures (above 56.1 degrees C) and lower detention times (less than 15 days) in the thermophilic digesters seemed to result in problems with degradation of volatile acids, particularly propionic acid.

Bacteria, Anaerobic↗
PubMed1989

Effects of the oviduct and wheat germ agglutinin on enzymatic digestion of porcine zona pellucidae.

Seventy-two crossbred gilts were utilized to examine whether the oviduct rendered zona pellucidae resistant to protease digestion, whether the uterus reversed this resistance and whether such a uterine reversal was necessary for hatching. Oocytes were aspirated from follicles 22 to 28 h after onset of estrus (d 0); oviductal and uterine oocytes or embryos were collected on d 1 to 6. These oocytes and embryos were subjected to a solution containing .1% trypsin and .1% pronase (37 degrees C) for observation of zona pellucidae digestion. Zonae of oviductal oocytes were more (P less than .001) resistant to digestion than were follicular oocytes. Placement of follicular oocytes in oviducts for 30 min rendered zona pellucidae more (P less than .001) resistant to protease digestion than oocytes not exposed to oviductal secretions. Resistance of zona pellucidae to proteases, however, decreased (P less than .001) after entry into the uterus. Zonae of morulae retained in oviducts took longer (P less than .001) to digest than those recovered from the uterus. Blastocysts also were treated with wheat germ agglutinin (WGA; 50 micrograms/ml) for 40 min to determine whether artificial induction of zona resistance to enzymatic digestion affected the ability of embryos to hatch. Though WGA treatment delayed (P less than .001) enzymatic digestion of zona pellucidae, time from collection to hatching was not affected. This experiment indicated that the oviduct delayed enzymatic digestion of the zona pellucidae, whereas the uterus reversed this delay. The re-establishment of enzyme susceptibility after uterine entry, however, appeared to be unrelated to the subsequent ability of blastocysts to hatch.

Animals↗
PubMed2000

Antimicrobial properties of pepsin-digested lactoferrin added to carrot juice and filtrates of carrot juice.

The objective of this study was to determine the antimicrobial activity of pepsin-digested lactoferrin added to carrot juice and filtrates prepared from carrot juice. Lactoferrin isolated from raw skim milk was digested by pepsin for 4 h at pH 3. The digest of lactoferrin was lyophilized, and the antimicrobial activity of the digests was determined in peptone-yeast-glucose broth, carrot juice, permeate from carrot juice, and the dialysate of carrot juice permeate using Escherichia coli (American Type Culture Collection strain 35343) as the test organism. Growth of E. coli and the inhibitory effect of the peptide were greater in peptone-yeast-glucose broth at pH 7 than at pH 4. The peptic digest of lactoferrin did not have antimicrobial properties in carrot juice at concentrations of less than 10 mg/ml of juice. Carrot juice was filtered through a membrane with a molecular weight rejection of 10,000 or 500 Da, and the permeate was dialyzed against distilled water. Growth of E. coli was delayed in the filtrate by 5 mg but not by 1 mg of the peptic digest of lactoferrin per ml of filtrate. Bacterial counts of the control and experimental samples were not significantly different after 24 h of incubation. The peptic digest of lactoferrin at a concentration of 5 mg of digest per ml of dialysate was bacteriostatic toward E. coli after 24 h of incubation at 23 degrees C. Dialysis of permeate caused a percentage reduction in cation concentration in the permeate ranging from 69.23% (Co) to 99.32% (Na). The antimicrobial activity of lactoferrin added to carrot juice was probably inhibited by cations.

Animals↗
PubMed2000

Anaerobic digestion of solid waste: state-of-the-art.

In order to make a correct assessment of the state-of-the-art of the technology, a study was made on the development of digestion capacity for solid waste in Europe. The study was limited to plants in operation or under construction that were treating at least 10% organic solid waste coming from market waste or municipal solid waste. A total treatment capacity for solid waste organics, excluding the tonnage used for sewage sludge and manures, evolved from 122,000 ton per year in 1990 to 1,037,000 ton available or under construction by the year 2000 in 53 plants across Europe, an increase by 750%. Both mesophilic and thermophilic technologies have been proven, with about 62% of capacity being operated at mesophilic temperatures. Wet and dry digestion are almost evenly split, while a clear choice was made for one-phase systems instead of two-phase systems, which represent only 10.6% of capacity. The capacity provided by co-digestion systems is limited, while there is a rising interest in digestion of mixed household waste. The reliable performance has been demonstrated for all types of anaerobic digestion systems. On the basis of the Dranco technology, a single-phase thermophilic dry digestion process, performances were reached similar to high-rate wastewater digestion. An annual average loading rate of 18.5 kg COD/m3.day, resulting in a biogas production of 9.2 m3/m3 reactor.day was obtained at a full-scale plant. The plant operated at a retention time of 15.3 days. Feedstocks range from clean organic wastes (31% dry matter) to heavily polluted grey waste organics (57% dry matter). Average dry matter concentrations of the digested residue of 41% were obtained.

Bacteria, Anaerobic↗
PubMedDate not supplied

[The examination of the digestive tract in patients with iron-deficiency anemia].

According to literature the gastroenterologic consultations for iron-deficiency anemia are quite frequent. The aim was the evaluation of the part played by gastrointestinal examinations for the diagnosis of iron-deficiency anemia. There were 115 patients admitted in the Medical Clinic between 1998-1999, with iron-deficiency anemia in the absence of macroscopic bleeding who carried out upper or lower endoscopy. A digestive lesion which account for iron deficiency anemia was identified in 35% of the cases. In the upper digestive tract there were 60%, in decreasing order of frequency: peptic ulcer, gastric cancer, erosive gastritis, angiodysplasia. In the lower digestive tract were 35% of the cases (colorectal cancer, polyps, angiodysplasia and hemorrhoids). In 5% of the cases there were found synchronization of the digestive tract lesions. So the digestive tract examination is worth doing because it establishes the diagnosis in 35% of the cases with few symptoms. The digestive tract lesions are more frequent in the upper tract, but they are more severe in the lower digestive tract. The possibility of the synchronization of lesions proves the necessity of carrying out the complete examination of the whole digestive tract.

Adult↗
PubMed2002

Removal of fecal coliforms by thermophilic anaerobic digestion processes.

Recent U.S. EPA regulations (40 CFR Section 503) specify maximum concentrations of pathogens and metals for Class A wastewater treatment plant sludges. The most common sludge process is mesophilic (35 degrees C) digestion which stabilizes the solids, produces a combustible gas but does not create an effluent that meets the 503 Class A pathogen requirements. This investigation was conducted to determine whether anaerobic digestion processes incorporating a thermophilic stage could achieve 503 Class A pathogen levels. The research reported here was a bench-scale screening study meant to identify the most promising process alternatives for further investigation. Fecal Coliform (FC) concentrations were used to assess disinfection efficiency. Digesters were 30 L capacity fed semi-continuously in draw-fill mode. Digester startup was rapid to produce true thermophiles. Temperature staging and pH were assessed in 3 sets of experiments: Set 1 were one stage ("acid phase"), Set 2 were one stage ("acid + methane phases") and Set 3 were two stage ("acid phase" then "methanogenic phase"). Feed was a 1:1 mixture of Thickened Waste Activated Sludge and Primary Sludge. The following anaerobic digestion configurations and operating parameters allowed the production of digested sludge with a mean FC concentration statistically less than 10(3) (the regulatory value for Class A sludge): thermophilic single stage acid phase at 52 and 62 degrees C; thermophilic single stage acid + methane phase at 48 degrees C, 52 degrees C and 62 degrees C; two-stage mesophilic acid phase followed by mesophilic methane phase; two stage mesophilic acid phase followed by thermophilic methane phase at 48 degrees C, 52 degrees C and 62 degrees C. If the maximum digested FC concentration must be below 10(3) MPN/g TS then the following digester configurations and operating conditions will be compliant: two stage mesophilic acid phase followed by thermophilic methane phase at 52 degrees C and 62 degrees C.

Bacteria, Anaerobic↗
PubMed1992

Extensive digestion of Na+,K(+)-ATPase by specific and nonspecific proteases with preservation of cation occlusion sites.

This paper extends our recent report that renal Na+,K(+)-ATPase is digested by trypsin in the absence of Ca2+ and presence of Rb+ ions to a stable 19-kDa fragment and smaller membrane-embedded fragments of the alpha chain and essentially intact beta chain. These are referred to as "19-kDa membranes." Occlusion of both Rb+ (K+) or Na+ ions is preserved, but ATP-dependent functions are lost (Karlish, S. J. D., Goldshleger, R., and Stein, W. D. (1990) Proc. Natl. Acad. Sci. U.S.A. 87, 4566-4570). We now show that extensive digestion with nonselective fungal proteases (Pronase and proteinase K) alone, in combination, or after tryptic digestion can remove up to 70% of membrane protein without destroying Rb+ occlusion. In the most heavily digested membranes, the 19-kDa fragment or a slightly shorter 18.5-kDa fragment and smaller fragments of the alpha chain remain, whereas the beta chain is largely digested, leaving smaller membrane-embedded fragments (13-15 kDa). For either trypsin or Pronase digestion, preservation of Rb+ occlusion and the specific fragmentation pattern is observed only in the absence of divalent metal ions (Mg2+ or Ca2+) and presence of either Rb+ or Na+ or congener ions. Tryptic digestion at pH 7.0 can split the beta chain into two fragments of approximately 50 and 16 kDa joined by an S-S bridge. The 16-kDa fragment is protected against further digestion by the presence of Rb+ ions, but probably is not directly involved in occluding cations. Tryptic 19-kDa membranes show a clear and reproducible fragmentation pattern in which all predicted membrane segments are identifiable. Families of fragments from 19-kDa membranes, including seven peptides of 7.6-11.7 kDa, have been separated by size-exclusion high performance liquid chromatography, concentrated, and resolved on 16.5% Tricine gels. N-terminal sequences of the different fragments have been determined after transfer to polyvinylidene difluoride paper. The most interesting findings are as follows. (a) Whereas the 19-kDa tryptic fragment begins at Asn831 as reported previously, the 18.5-kDa Pronase fragment begins at Thr834. (b) Fragments in tryptic 19-kDa membranes of 7.6-11.7 kDa begin at Asp68, Ile263, and Gln737, respectively. These include all putative transmembrane segments other than those in the 19-kDa fragment. (c) A Pronase fragment of 7.8 kDa begins at Thr834, i.e. apparently the 19-kDa fragment has been partially cut, without loss of Rb+ occlusion. (d) Tryptic 16- and approximately 50-kDa fragments of the beta chain begin at Ala5 and Gly143, respectively.(ABSTRACT TRUNCATED AT 400 WORDS)

Amino Acid Sequence↗
PubMed2004

[Determination of trace zinc, manganese, cadmium and lead in aloe by microwave-digestion atomic absorption spectrometry].

A microwave digestion procedure was developed for the determination of trace Zn, Mn, Cd and Pb in aloe-leaf cuticle and aloe-leaf gelatin, using the obturated vessel microwave digestion system with a pressure controlling part, and the amounts of these trace metallic elements were determined by atomic absorption spectrometry after microwave digestion. The effects of the composition of digestion solution, the ratio of the sample to digestion solution, and the digestion time were studied. It is satisfactory to apply the microwave digestion procedure to the determination of Zn, Mn, Cd and Pb under the optimized condition with the recovery of 95.0% to 110.0% and RSD of 0.3% to 6.2%. The results show that this method is rapid and simple with low environmental contamination and complete digestion of the sample.

Aloe↗