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J Harmeyer

Publications and source records attributed to J Harmeyer.

At least 19 recordsLinked to original sources
PubMed1992

The effects of 1,25-dihydroxyvitamin D-3 deficiency on Ca(2+)-transport and Ca(2+)-uptake into brush-border membrane vesicles from pig small intestine.

BBMV were prepared from duodenal segments of untreated, 1,25-(OH)2D3- or vitamin D-3-treated rachitic piglets and from non-rachitic controls by the Mg2+ precipitation method. The rachitic piglets were offspring from the 'Hannover Pig Strain' which suffer from pseudo vitamin D-deficiency rickets, type I (no renal 1-hydroxylase activity). Initial uptake of Ca2+ (up to 35 s) at low [Ca2+] (between 0.02-0.25 mmol/l) into isolated BBMV consisted of a saturable and non-saturable component. The apparent Vmax of the saturable component was significantly lower in rachitic piglets than in control piglets. In the presence of an inside negative potassium diffusion potential, the difference in uptake extended over at least 15 min. The apparent Km of Ca(2+)-uptake was not influenced by the rachitic condition. Treatment of rachitic piglets with sequential doses of 1,25-(OH)2D3 for three days (1 microgram/day) or with a single dose (2.5 mg) of vitamin D-3 elevated the saturable Ca(2+)-uptake component to values similar to those of control piglets. Addition of 1 mmol/l verapamil to the vesicular suspension inhibited Ca(2+)-uptake in BBMV of control piglets by 40-60% but was without effect on preparations from rachitic piglets. It was concluded from the study that 1,25-(OH)2D3 dependent Ca(2+)-uptake into BBMV constituted a saturable process which can be inhibited by a known Ca(2+)-channel blocking agent. It appears that 1,25-(OH)2D3 increases the number of verapamil sensitive Ca(2+)-transport components in brush-border membranes. The vitamin D-dependent changes in vesicular Ca(2+)-uptake were paralleled by the expression of an active transmural Ca(2+)-transport across the mucosa.

Animals↗
PubMed1992

Effect of niacin supplementation on the concentration of niacin in rumen and duodenal digesta and in whole blood of sheep.

1. Niacin concentrations in rumen liquor, duodenal digesta and blood, and daily duodenal flow of niacin were measured in four wethers which were fed an oatstraw grain concentrate diet (with normal niacin content) or an oatstraw maize diet (with low niacin content). The effect of an intraruminal supplementation of 2 mmoles nicotinic acid (NIA) or nicotinamide (NAM) on concentrations of NIA and NAM in gastrointestinal contents and blood and on daily duodenal flow of NIA and NAM was studied. The animals were equipped with rumen fistula and duodenal re-entrant cannulae. 2. NIA concentration in strained rumen liquor was 384 and 264 nmol/ml and daily duodenal flow of niacin was 616 and 528 mumoles/d in animals fed normal or low niacin diet, respectively. Intraruminal administrations of 2 mmoles of NIA or NAM raised NIA concentration in strained rumen liquor for approximately 6 h. About 20% of the administered dose of NIA or NAM passed out of the rumen and resulted in a 41% increase in daily duodenal flow of niacin. The remaining 80% of the administered dose of NIA or NAM disappeared from rumen liquor without being washed out. 3. Supplemented NAM was rapidly hydrolyzed to NIA and ammonia when administered into the rumen. 4. NAM concentration in blood appeared to be unaffected by the dietary content of NIA or by niacin supplementation. 5. The NIA concentration in strained rumen liquor was positively related with niacin content of the diet. Increases in duodenal flow of niacin had no marked effect on concentration of NAM in blood. It appeared that feeding diets with different NIA content affected apparent niacin synthesis in the rumen.

Animal Feed↗
PubMed1991

A technique for the collection of reticular effluent of sheep.

Two sheep were equipped with rumen and omasal fistulae. A teflon tube with 1 mm outer diameter (OD) was permanently fixed between the abomasal fistula and the reticulo-omasal orifice. The effluent sampling tube was introduced through the abomasal cannula, through the omasal canal into the reticulo-omasal orifice by aid of the teflon tube. The technique allowed direct collection of reticular effluent from sheep. Intermittent flow of reticular effluent was observed. The moments of flow coincided with the end of the second phase of reticular contractions. From the flow pattern it was concluded that the motility of the reticulo-omasal orifice was not affected by the sampling procedure. From the similarities in the pH values, DM contents, and total protozoal counts in the effluent and in the reticular samples, it was concluded that representative samples of effluent could be obtained by the method. One animal was used for sampling for a period of eight months and then again 2 1/2 years later. A fraction of 97 to 98% of the DM present in the reticular effluent and in the reticular samples passed a sieve with 1 mm pore size. From the analyses of reticular content and reticular effluent it was concluded that the reticulo-omasal orifice does not have a significant discriminating function for the selective passage of particles and protozoa into the omasum.

Animals↗
PubMed1991

Effects of calcitriol on stimulation of ion transport in pig jejunal mucosa.

1. Active sodium (Na+) and chloride (Cl-) fluxes were studied in vitro in Ussing-type chambers with stripped jejunal mucosa of piglets which suffered from pseudo-vitamin D deficiency rickets, type I. The piglets are devoid of renal calcitriol (1,25-dihydroxy vitamin D3) production and have only small amounts of calbindin in their jejunal enterocytes. 2. In the presence of 0.01 mM-indomethacin non-stimulated short-circuit current (Isc), transepithelial potential difference (PD), tissue conductance (Gt) and unidirectional Na+ (JNa) and Cl- fluxes (JCl) were not affected by the low calcitriol (LC) concentration in plasma. 3. Adding 10 mM-theophylline to the serosal solution in the presence of 0.01 mM-indomethacin caused significantly greater increases in Isc in LC mucosa than in mucosa of vitamin D3-treated and control piglets with normal calcitriol (NC) concentrations in plasma. Omission of indomethacin significantly increased Isc stimulation provoked by theophylline with LC and NC mucosa. The increase, however, was significantly greater with LC than with NC mucosa. 4. Omission of calcium (Ca2+) from the serosal bathing solution significantly depressed Isc stimulation by 10 mM-theophylline in indomethacin-treated LC and NC mucosa. But depression was greater with LC than with NC mucosa. 5. Blocking Ca2+ entry into the cytosol by adding either 0.1 mM-TMB-8 or 0.5 mM-d,l-verapamil to the serosal bathing solution abolished the difference in Isc response to theophylline between indomethacin-treated LC and NC mucosa due to greater depression of Isc in LC than in NC mucosa. 6. The combined effects of theophylline and A23187 on Isc stimulation were calcitriol dependent. In the presence of indomethacin this dependence was only significant when A23187 was given prior to theophylline. In the absence of indomethacin the combined effects of A23187 and theophylline on Isc were always significantly greater in LC than in NC mucosa, irrespective of the order of adding the two agents. 7. Addition of theophylline stimulated net Na+ and Cl- secretion in indomethacin-treated LC and NC mucosa. The increases of net Na+ and Cl- fluxes fully accounted for the rise of Isc with NC mucosa but accounted only partly for the increase in Isc with LC mucosa. This resulted in significant increase in theophylline-stimulated residual ion flux (JR) in LC mucosa which probably resulted from enhanced secretion of bicarbonate.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1990

Binding properties of plasma vitamin D-binding protein and intestinal 1,25-dihydroxyvitamin D3 receptor in piglets with pseudo-vitamin D-deficiency rickets, type I: treatment effects with pharmacological doses of vitamin D3.

The effective treatment of the rachitic symptoms of pseudo-vitamin D-deficiency rickets, type I (PVDRI) by massive doses of vitamin D3 was examined. For this purpose, the affinities and the maximum binding capacities (Bmax) of the plasma vitamin D-binding protein (DBP) and of the intestinal 1,25-dihydroxyvitamin D3 (1,25-(OH)2D3) receptor for vitamin D3, 25-hydroxyvitamin D3 (25-OHD3) and 1,25-(OH)2D3, were investigated in normal piglets and in rachitic piglets that suffered from PVDRI. The piglets were 5 to 10 weeks old and of both sexes. The Bmax of plasma DBP for 25-OHD3 was 6.77 +/- 0.45 microM for PVDRI piglets and 7.30 +/- 0.41 microM for control piglets and showed no differences between the two groups. Equilibrium association constants (Ka) of DBP for 25-OHD3 were 4.3 x 10(8) M-1 for PVDRI piglets and 4.0 x 10(8) M-1 for controls and showed also no differences between the two groups. Similarly the Ka of DBP for 1,25-(OH)2D3 was also the same for rachitic and control piglets (1.45 x 10(7) and 1.54 x 10(7) M-1, respectively). Due to the lower circulating concentration of 1,25-(OH)2D3 in the plasma of rachitic piglets compared to that of controls its free metabolite index was significantly lower in rachitic (0.42 +/- 0.05 x 10(-5)) than in control piglets (3.63 +/- 0.30 x 10(-5)). The Kd and Bmax of the intestinal nuclear receptor for 1,25-(OH)2D3 of rachitic and control piglets were 0.31 +/- 0.05 and 0.33 +/- 0.05 nM and 674 +/- 103 and 719 +/- 123 fmol/mg protein, respectively, and were also not different between the two groups of piglets. It was concluded from these observations that the rachitic symptoms of PVDRI piglets resulted solely from the lower free 1,25-(OH)2D3 concentration in plasma compared to that of normal piglets. The relative affinities of the intestinal 1,25-(OH)2D3 receptor for vitamin D3 and 25-OHD3 were also measured. It was found that 50% displacement of 1,25-(OH)2D3 from the intestinal receptor of PVDRI and control piglets required a 220,000- and 245,000-fold excess of the free concentration of vitamin D3, respectively, and a 20- to 42- and 23- to 71-fold excess of the free concentration of 25-OHD3, respectively.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1990

Studies of the porcine intestinal calcitriol receptor in pseudo-vitamin D deficiency rickets type I.

1. Calcitriol (1,25-dihydroxyvitamin D3) concentrations in plasma of humans and pigs with pseudo-vitamin D deficiency rickets type I (PVDRI) have been reported to be significantly lower than in normal subjects and animals. Sometimes, however, calcitriol concentrations are relatively high in these subjects and animals (50-80 pmol/l) and nevertheless clinical symptoms of rickets develop. We have studied whether or not the development of rachitic lesions in piglets with PVDRI is due to altered binding properties of the intestinal calcitriol receptor in addition to the defective renal production of calcitriol. PVDRI piglets with clinical and biochemical symptoms of rickets (hypocalcaemia, increased activity of alkaline phosphatase) and with calcitriol concentrations in plasma of 83.7 +/- 4.2 pmol/l (n = 7) were used. They were compared with unaffected piglets with normal calcitriol concentrations (178.0 +/- 17.7 pmol/l, n = 9). 2. The equilibrium dissociation constant (Kd) of the receptor in the PVDRI piglets (0.31 +/- 0.05 nmol/l) and in control piglets (0.33 +/- 0.05 nmol/l) and the maximum binding capacity (Bmax.) (674 +/- 103 and 719 +/- 122 fmol/mg of protein, respectively) were not different (n = 9). 3. The association rate constant (kass) at 4 degrees C [0.15 x 10(7) and 0.24 x 10(7) (mol/l)-1 min-1] and the dissociation rate constant (kdiss) (0.40 x 10(-3) and 0.48 x 10(-3) min-1; half-life of dissociation = 24.1 and 28.9 h, respectively) were also not different between diseased and control piglets.(ABSTRACT TRUNCATED AT 250 WORDS)

Alkaline Phosphatase↗
PubMed1990

Hypocalcemia reduces rate of disappearance of glucose from plasma.

The influence of hypocalcemia on glucose disposal from plasma was studied in 4.5 to 24 kg weaned, fasted, calcitriol deficient piglets, which suffered from type I inherited pseudo vitamin D deficiency rickets. The plasma glucose concentration of the piglets was clamped to 40% above its preinfusional level by a continuous intravenous infusion of glucose. This suppressed hepatic glucose production. Since the clamped plasma glucose concentration was below its renal threshold, the rate of steady state glucose infusion served as an estimate for glucose disposal from plasma. It was found that hypocalcemia, generated either by calcitriol deficiency or by continuous EDTA infusions, reduced glucose disposal from plasma by 56-76% compared to normocalcemic control piglets. It was suggested that the effect was not compounded by plasma phosphate, calcitriol or insulin. It was further suggested that hypocalcemia depressed the rate of glucose utilization.

Animals↗
PubMed1989

Purification procedure for the determination of niacin vitamers in gastrointestinal contents and blood.

A solid phase extraction procedure for subsequent simultaneous HPLC analysis of free nicotinic acid (NIA) and nicotinamide (NAM) in dried or liquid rumen and gastrointestinal contents from sheep is described. Twenty-five mg dried samples were suspended in 1.0 ml of 0.1 mol/l Li2SO4 and centrifuged. The supernatants were passed through two 500 mg solid phase extraction columns (Bond Elut NH2 and Sep Pak C18), mounted in series, and eluted by a four step pH gradient procedure. Recoveries of the two vitameres were between 70 and 75%. Purification was satisfactory when the method was applied to different fractions of rumen content (e.g. to food residues, to a microbial preparation and to rumen fluid), to intestinal contents of sheep and to blood. In rumen fluid no free NIA and NAM was found. Food particles and rumen microbes contained no free NAM.

Animals↗
PubMed1989

Evaluation of elution parameters in reversed phase HPLC for the determination of niacin vitamers and metabolites.

A procedure for separation of nicotinic acid (NIA), nicotinamide (NAM), nicotinuric acid (NUR) and N1-methyl-nicotinamide (NMN) from biological samples by isocratic HPLC is described. The effects a) of different buffer systems (citrate, acetate, propionate), b) of different pH values (between pH 2.4 and 3.35), c) of different ionic concentrations of the eluents (between 10 and 100 mM) and d) of different methanol concentrations added to the eluent on retention times of the four compounds were tested. Results were described by multiple regression equations which allow selection of suitable analytical conditions according to the specific composition of different biological materials. The procedure yielded satisfactory separation of NIA and NAM from various purified fractions of rumen and intestinal contents and blood.

Animals↗
PubMed1989

Role of 1,25-(OH)2D3 during pregnancy; studies with pigs suffering from pseudo-vitamin D-deficiency rickets, type I.

Biochemical parameters of Ca homeostasis in fetal and maternal plasma and placental transfer of Ca, Pi and vitamin D metabolites were measured during pregnancy and at parturition. Control pigs and pigs with inherited pseudo-vitamin D-deficiency rickets, type I (PVDR), which are devoid of renal calcitriol production, were used. Although sows with PVDR normally require treatment with massive doses of vitamin D at intervals of 4 weeks to stabilize Ca and Pi concentrations in plasma, these plasma parameters tended to normalize during the first 3 months of pregnancy when the vitamin D treatment was discontinued about 4 weeks before conception. In homozygote sows plasma calcitriol concentrations remained unphysiologically low and the 25OHD3 concentrations increased steadily during pregnancy reaching higher levels than those found in control sows. Despite hypocalcaemia and hypophosphataemia of the homozygote sows at term, fetal Ca and Pi concentrations were normal. This demonstrated a higher feto-maternal concentration gradient in PVDR pigs than in control pigs. It is concluded that maintenance of Ca and Pi homeostasis of the feto-maternal system, including active transplacental transport in pigs, is at least partly independant from calcitriol.

Alkaline Phosphatase↗
PubMed1989

Placental transport of calcium and phosphorus in pigs.

The role of vitamin D in regulating placental transport of calcium and phosphate in pigs was studied using the "Hannover Pig Strain" which suffers from pseudo-vitamin D-deficiency rickets, type I. Sows and fetuses of normal phenotype (heterozygotes) and of homozygote phenotype which suffered from clinical symptoms of rickets were used. The homozygote animals are devoid of renal 25-cholecalciferol-1-hydroxylase. In the rachitic sows which normally depend on treatment with pharmacological doses of vitamin D3 at intervals of four to six weeks, vitamin D-treatment was discontinued two months before conception. Ca, P and 1.25-(OH)2D3 concentrations in plasma of sows and fetuses (Aa. umb., V. umb.) were measured in samples obtained at term during cesarian section. Mean concentrations of Ca and P in heterozygote sows at parturition were 2.34 mmol/l and 2.33 mmol/l, respectively, and were significantly higher than in homozygote sows, 1.58 mmol/l and 1.26 mmol/l, respectively. Ca concentrations in plasma of the umbilical vein of fetuses from both homozygote and heterozygote sows were normal, however, (3.23 mmol/l and 2.96 mmol/l, respectively) and statistically not different from each other. No significantly different P concentrations in arterial plasma of fetuses from heterozygote or homozygote sows were seen, either. The concentrations of Ca and P in the arterial umbilical plasma were significantly higher (p less than 0.001) than in venous plasma of both homozygote and heterozygote fetuses, indicating net placental transfer of these elements in both genotypes. The concentration of 1.25-(OH)2D3 in hypocalcemic sows at term (25.5 +/- 8.25 pg/ml) was significantly lower than that in the normocalcemic (heterozygote) sows (84.1 +/- 25.6 pg/ml). The 1.25-(OH)2D3 concentration in arterial plasma of fetuses from homozygote sows was only 46% that of fetuses from normocalcemic sows which showed transfer of calcitriol from mother to fetus. It is concluded from these studies that in pigs, renal production and physiological concentrations of 1.25-(OH)2D3 in either mother or fetus is not essential for the maintainance of the Ca and P homeostasis in the fetal-maternal system.

Animals↗
PubMed1988

Intestinal absorption of calcium in newborn piglets. Role of vitamin D.

The role of vitamin D for intestinal absorption of Ca was studied in neonatal piglets. Piglets of normal phenotype (heterozygotes) and piglets which suffered from pseudo-vitamin D deficiency rickets, type I, which were devoid of renal 25-cholecalciferol-1-hydroxylase were used for the experiments. Intestinal absorption of Ca was measured after an oral dose of 3-7 MBq 45CaCl2. Intestinal absorption of Ca was the same in heterozygotes and homozygotic rachitic piglets during the first 3-4 weeks of life. Ca absorption began to decline in rachitic piglets at the age of 4 weeks. In 8-week-old rachitic piglets intestinal Ca absorption was 50% of control piglets. Body weights of heterozygotes and rachitic piglets were the same at birth and no different weight gains were seen between the two groups during the first 4-5 weeks of life. No differences were observed during the first weeks of life in the concentrations of plasma Ca, inorganic-phosphate and alkaline-phosphatase activity between the groups. Hypocalcemia and hypophosphatemia developed in rachitic piglets between the 3rd and 5th weeks of life. Concentrations of 1,25-(OH)2D3 in plasma declined in heterozygote piglets from 130 +/- 26 to 88 +/- 19 pg/ml and in rachitic piglets from 67 +/- 37 to 23 +/- 11 pg/ml during the first 6 weeks. An intestinal nuclear 1,25-(OH)2D3 receptor was absent in neonatal piglets of both experimental groups. It is concluded that intestinal absorption of Ca in piglets during the first 2-4 weeks of life is independent of vitamin D.

Alkaline Phosphatase↗
PubMed1987

Phosphate transport in brush-border membranes from control and rachitic pig kidney and small intestine.

1. Na-Pi co-transport was analysed using renal cortical and small intestinal brush-border membrane vesicles which were isolated from control (normal, heterozygotes) and rachitic piglets (homozygotes). 2. A kinetic analysis of Na-dependent initial linear uptake of Pi was performed using vesicles obtained from control animals. The results suggest similar kinetic properties for the renal and small intestinal co-transport system. (i) A sigmoidal dependence on Na concentration of Pi uptake suggests the involvement of more than one Na ion in the co-transport. (ii) Increasing Na concentration leads to an increase in the apparent affinity of the transport system for Pi and has minimal effect on the apparent Vmax (maximum velocity of uptake). (iii) Increasing pH leads to an increase in Pi transport rate. 3. The kinetic characteristics of the Na-Pi co-transport system in vesicles obtained from rachitic animals were similar to those in controls. The apparent Vmax, but not the apparent Km (Michaelis constant) for Na and Pi, is reduced in intestinal and renal brush-border membranes isolated from rachitic animals as compared to control animals. Injection of vitamin D3, three days prior to killing of rachitic litter-mates, increased the Na-Pi uptake rate in the brush-border membrane vesicles isolated from these piglets. 4. It is concluded that intestinal and renal brush-border membranes from piglets contain a similar Na-Pi co-transport system and that in vitamin-D-dependent rickets the number of operating transport units is reduced in both membranes.

Animals↗
PubMed1987

Vitamin D3 metabolism in a pig strain with pseudo vitamin D-deficiency rickets, type I.

Vitamin D metabolism was studied in the 'Hannover Pig', a strain which suffers from pseudo vitamin D-deficiency rickets, type I. Animals of this strain are known to be devoid of renal 25-hydroxyvitamin D3-1 alpha-hydroxylase and -24-hydroxylase activities. Pigs with florid rickets and hypocalcaemia were treated with single im injections of 0.25 to 1.25 mg of vitamin D3, doses that have been shown in previous studies to be effective in producing transient healing of rachitic symptoms. The levels of vitamin D3 and its most relevant physiological metabolites in plasma were estimated at intervals before and after this vitamin D3 treatment. Vitamin D3 rose from 14.8 +/- 8.1 to 364 +/- 190 nmol/l (mean +/- SD) 2 to 3 days post injectionem, 25-hydroxyvitamin D3 from 131.0 +/- 46.2 to 1068 +/- 160 nmol/l within 7 days post injectionem. The 1 alpha, 25-dihydroxyvitamin D3 concentration in plasma was elevated from 73.9 +/- 25.0 to 281 +/- 168 pmol/l 2 to 3 days post injectionem and declined continually from that time. 24R,25-dihydroxyvitamin D3 and 25S,26-dihydroxyvitamin D3 levels after treatment showed different responses in different animals being either elevated or unchanged. Clinical healing of the pigs with these doses of vitamin D3 was attributed to the transient rise of 1 alpha,25-dihydroxyvitamin D3 in plasma. It was assumed that 1 alpha,25-dihydroxyvitamin D3 synthesis takes place under these circumstances in extrarenal tissues.

24,25-Dihydroxyvitamin D 3↗
PubMed1986

Absence of renal 25-hydroxycholecalciferol-1-hydroxylase activity in a pig strain with vitamin D-dependent rickets.

Cholecalciferol-1-hydroxylase activities were estimated in renal cortex homogenates and mitochondrial preparations from three groups of 6- to 12-week-old pigs. Five animals suffering from an inherited form of vitamin D-deficiency rickets showed symptoms of florid rickets when used for this study. Six pigs were normocalcemic heterozygous litter mates of the rachitic strain and three pigs were normal controls (German land-race and wild pigs). The renal cortex homogenates and mitochondrial preparations were incubated for 5-30 min at 37 degrees C with 25-(26-27-methyl-3H) OHD3 as substrate. 1,25(OH)2D3 was subsequently identified in normal phase (Zorbax-Sil) and reversed phase (Zorbax-ODS) HPLC eluates. 1-hydroxylase activities were demonstrated in both normal controls and heterozygote offspring and were ten times above minimum detectability of the assay. The km was 255 +/- 74 (SD) and 278 +/- 85 nmol X 1(-1) in controls and heterozygote offspring, respectively. The Vmax in the two groups was between 0.11 and 0.794 and decreased with age of the animals. Km and Vmax did not differ between the two groups. In homozygous, hypocalcemic rachitic animals no 1-hydroxylase activity was detectable in either homogenates or mitochondrial preparations. Addition of kidney homogenate from a rachitic animal to a homogenate from a normal pig did not specifically depress 1-hydroxylase activity in the mixture. Treatment of rachitic pigs with 1.0 microgram/day of 1,25(OH)2D3 for 4 weeks also had no effect on 1-hydroxylase activity. It is concluded that the rachitic pigs suffer from an inborn error of renal 1,25(OH)2D3 production.(ABSTRACT TRUNCATED AT 250 WORDS)

24,25-Dihydroxyvitamin D 3↗
PubMed1986

The passage of protozoa from the reticulo-rumen through the omasum of sheep.

1. Protozoa in rumen contents and omasal effluent of growing wethers were counted. The wethers were equipped with rumen and abomasal cannulas, and omasal sleeves attached to the omasal-abomasal orifice. Rumen fluid dilution rates were elevated by continuous infusions of hypertonic mineral solutions (3-4 litres/d) for 24 d. Rumen contents and omasal effluent were sampled between 9 and 21 h during the last 10 d of each experiment. 2. Protozoal concentrations in omasal effluent were only 0.2-0.3 those found in the rumen under normal conditions. The ratio of protozoal concentrations in rumen: those in omasal effluent was for small Diplodinium spp. 4.6 (SD 0.9), for Ophryoscolex spp. 4.3 (SD 1.0), for Dasytricha ruminantium 4.0 (SD 0.5), for Isotricha spp. 3.8 (SD 0.8), for Entodinium spp. 3.6 (SD 0.9) and for Polyplastron multivesiculatum 2.6 (SD 0.5). 3. Elevation of rumen fluid dilution rate by 20 and 55% respectively, increased protozoal concentrations in omasal effluents from 22 to 33% and from 31 to 47% those in rumen contents. The apparent residence times of protozoa in the rumen were decreased 50% by the infusion of a mineral-salt solution. The increase in rumen fluid dilution rate had no significant effect on concentrations of protozoa in the rumen or on the differences of the apparent residence times between different species. The apparent residence time of holotrichs remained the same before and after infusion of the mineral-salt solution. 4. Apparent residence times of individual species of protozoa in the rumen were, under normal feeding conditions, 2.55 d, and were four to six times longer than the mean residence time of CrEDTA in the rumen.

Animals↗
PubMed1986

[The quantitative determination of vitamin D3 and its metabolites in plasma].

A method is described which enables determination of vitamin D3 and its physiologically most important metabolites, i.e. 25-OHD3, 24,25-(OH)2D3, 25,26-(OH)2D3 and 1,25-(OH)2D3 in a plasma sample of about 2 to 4 ml. The whole procedure involves two preparative and one analytical steps: Extraction with methanol/methylene chloride (2:1), chromatographic separation on Lipidex 5000 using a stepwise gradient of n-hexane and chloroform and finally HPLC separation on Zorbax-Sil columns with n-hexane isopropanol mixtures and subsequently reversed phase separation on RP 18-columns and mixtures of methanol and water. Except for 1,25-(OH)2D3 all D compounds were quantified by UV-detection with 1.4 ng of substance being the lowest detectable amount. 1,25-(OH)2D3 was measured by radioimmunoassay. Prior to HPLC analysis the extract was separated into three fractions on Lipidex 5000 which contained 1) vitamin D3, 2) 25-OHD3 and 3) the dihydroxy metabolites. The three fractions were separated by HPLC using different mixtures of isopropanol/n-hexane and methanol/water, respectively. Retention times of the individual D-components longer than 10 min appeared to be essential to separate these compounds from accompanying material. Overall recoveries of the individual metabolites were for vitamin D3 48.9%, for 25-OHD3 54.2%, for 24,25-(OH)2D3 50.9% and for 1,25-(OH)2D3 52.5%. Application of the methods to plasma samples from pigs with pseudovitamin D deficiency rickets, typ I, revealed a reduced concentration of 1,25-(OH)2D3 and 24,25-(OH)2D3 and an elevated level of 25-OHD3 in these animals. The results obtained by this method contributed substantially to a better understanding of the aetiological factors associated with this disease.

Biotransformation↗