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H Daniel

Publications and source records attributed to H Daniel.

At least 145 records · Page 8Linked to original sources
PubMed1986

Effect of proteins on availability of zinc. II. Bioavailability of zinc from casein and whey protein--retention study in young rats.

The availability of zinc from two semi-synthetic diets with isolated whey protein (Wp D) or with isolated casein (Cas D) as protein component (20% W/W) was compared in a 21-day study with growing male rats (initial weight 40 g; 14 animals/group). Zinc concentration in both diets (18 ppm) was adequate to meet the requirements of the animals fed ad libitum. For radiolabeling approximately 13 micrograms 65Zn (= 4 microCi) was given daily by intragastric intubation to each animal. The investigation was designed primarily as a retention study, but also general parameters like weight development, food and water intake, organ weights etc. were registered and the activity of alkaline phosphatase was determined in serum and femur tissue. A significantly higher percentage of 65Zn was retained in the whole body from the Wp D (36.5%) than from the Cas D (31.6%) during the experimental period. The same is valid for the percentage retention of 65Zn in the femur and for the 65Zn concentration in femur and hair as well as for the total zinc concentration (65Zn and non-labeled zinc) of the femur. The other parameters determined were not unequivocally influenced by the protein component of the diet. The study clearly demonstrated that the availability of zinc by the growing rat was better from a diet with whey protein than from one with casein as the protein component. The reason on this phenomenon has to be elucidated by further investigations.

Alkaline Phosphatase↗
PubMed1986

Effect of metabolizable sugars on the mucosal surface pH of rat intestine.

In a layer juxtaposed to the mucosal surface of distal duodenum and of jejunum, and designated as "acid microclimate," the proton concentration is significantly higher than in the bulk phase of the intestinal lumen. The aim of the present study was to quantify the effect of different sugars on the mucosal surface pH value when these substrates were either added to the in vitro preparation of rat distal duodenal and mid-jejunal segments or administered by intragastric intubation and by i.v. infusion. All pH measurements were carried out in vitro by surface microelectrodes in oxygenated phosphate buffer. Glucose, fructose, mannose, galactose and 3-O-methylglucose were applied in vitro, glucose, maltose, fructose, galactose, 3-O-methylglucose and whey protein for the intragastric intubation and glucose, fructose and galactose for the intravenous infusion. Only substrates that could be metabolized in the intestinal epithelia were able to depress surface pH to a considerable extent. Substrate concentration at which half-maximum decrease of surface pH was obtained (K delta pH) was calculated to be 4.5 mM for glucose, 14.5 mM for fructose and 34.5 mM for mannose. The study was the first to demonstrate that metabolizable sugars are not only able to lower surface pH of intestinal epithelia when they are added in vitro but that they are also effective after intragastric intubation or i.v. infusion. It is plausible that generation of the protons, which are secreted into the acid microclimate zone, is closely related to the intracellular metabolization of glucose. The existence of a high proton concentration on the immediate mucosal surface could be of considerable significance for the absorption of weak electrolytes, a group to which different nutrients belong.

3-O-Methylglucose↗
PubMed1986

Aluminum lactate treatment alters the lung biological activity of quartz.

Previous studies of surface modification of quartz particles have suggested that the biological activity of silica is at least in part related to its surface properties. In the present study, we exposed the tracheal lobe of 8 sheep to either 100 ml saline (saline group), 100 mg of quartz (Minusil-5) in 100 ml saline (SI group) or 100 mg of Al lactate treated quartz in 100 ml saline (SI-Al group). The 24 sheep were studied by bronchoalveolar lavage at days 0, 12, 24, 40, 60 and by autopsy at day 60. In the saline group, BAL analyses were as previously reported [1]. In the SI group, we found significant and sustained increases in total BAL cells (x 2, P less than 0.05), macrophages and lymphocytes (x 2, P less than 0.05), neutrophils (x 5-10, P less than 0.01), IgG (x 1.2-1.8, P less than 0.05), fibronectin (x 2-3, P less than 0.05), lactate dehydrogenase (x 3, P less than 0.01) and alkaline phosphatase (x 2, P less than 0.05). Histologically, a macrophagic and lymphocytic alveolitis was observed at day 60. In the SI-Al group, these changes were significantly attenuated and in the above parameters, SI-Al group did not differ from saline group after day 24. These data of BAL and histology of the sheep tracheal lobe model document clearly that aluminum lactate treatment alters the biological activity of quartz.

Animals↗
PubMed1986

Intestinal uptake of nicotinic acid as a function of microclimate-pH.

The investigations aimed at clarifying the pH-dependence of 3H-nicotinic acid uptake into isolated strips of rat jejunum. Nicotinic acid is a weak-electrolyte with pKa 4.90. Thus, it was anticipated that the penetration rate of this vitamin into the intestinal epithelial cells is closely related to the amount of the diffusible i.e. non-ionic form which for its part is a function of the "virtual pH" on the mucosal surface. As determined by microelectrodes the surface pH was found to be between 5.41 and 6.80 when the strips were incubated in buffers between pH 4.5 and 9.0. At surface pH 5.83 the unidirectional flux rate was twice as high, at pH 5.41 three times as high as at surface pH values between 5.95 and 6.80. At each pH the unidirectional flux of nicotinic acid was linearly dependent on the substrate concentration in a range between 0.1 microM and 1 mM, indicating simple diffusion as transport mechanism. Accordingly, the uptake rate was not affected by the substrate analogon, isonicotinic acid (5 microM and 250 microM). It can be concluded that the predominant part of the nicotinic acid is transported through the brush border membrane obeying the laws of a non-ionic diffusion. A relatively small portion of this substrate, however, was taken up by the tissue even when the vitamin was entirely dissociated, possibly by ionic diffusion or by binding.

Animals↗
PubMed1986

Chemistry of brotizolam and its metabolites.

Of a series of azepines annelated with two 5-ring heterocycles, 1, brotizolam (2-bromo-4-(2-chlorophenyl)-9-methyl-6H-thieno[3,2-f]-1,2,4-triazolo [4,3-a]-1,4-diazepine, We 941), 2, was found to possess excellent hypnotic properties. A summary of the two different methods of preparation of 2 (routes A and B) is given. Synthesis of the major metabolites of 2, 6-hydroxy-brotizolam (We 1061), 14, obtained from the intermediates 9 and 10 by method B, 2-bromo-4-(2-chlorophenyl)-9-hydroxymethyl-6H-thieno [3,2-f]-1,2,4-triazolo-[4,3a]-1,4-diazepine (WE 964), 16, and 2-bromo-4-(2-chlorophenyl)-6-hydroxy-9-hydroxymethyl-6H-thieno- [3,2-f]-1,2,4-triazolo-[4,3-a]-1,4-diazepine (We 1073), 17, are described in detail. In contrast to the classical 3-hydroxy-1,4-benzodiazepines, e.g. oxazepam, 14 isomerizes easily in weak alkali. This isomerization is discussed.

Animals↗
PubMed1985

Inferior olive destruction induces dysfacilitation of the red nucleus activity.

The spontaneous discharge frequency of the red nucleus neurones was evaluated in rat before and after total destruction of the inferior olive with the 3-acetylpyridine. It was found that the sustained firing recorded in the control animals (33.7 +/- 23.7/s) drastically decreased to a low rate (4.6 +/- 7.1/s) after the intoxication. This effect took place between 2 h 15 min and 2 h 45 min after the injection. which is the critical period corresponding to the inferior olive degeneration and the consequent climbing fiber deafferentation. It lasted at least as long as the acute experiment. The conclusions are reached that the inferior olive destruction leading to an enhanced cerebellar inhibition, produces a dysfacilitatory effect on the red nucleus neurones.

Animals↗
PubMed1985

Long term modification of cerebellar inhibition after inferior olive degeneration.

The long term effects of inferior olive destruction on the activities of the Purkinje cells and their target neurones in the cerebellar nuclei were studied in the rat. Careful observations were also made of motor behaviour throughout the study. Albino rats were injected with 3-acetylpyridine to produce a neurotoxic destruction of the inferior olive and then were used for acute recording experiments at 1-2 days, 5-7 days, 12-18 days, 35-38 days, 75-97 days and 230-252 days. After degeneration of the inferior olive, there was an initial period lasting for a few days, characterized by a high firing frequency of Purkinje cells associated with a very low level of activity of the neurones in the cerebellar nuclei. During this period, there was a deep depression of motor activity. A period of adaptation follows during the first month, characterized by a slow recovery of the initial firing frequency of the cerebellar units and a gradual recovery of spontaneous locomotion; nevertheless the firing pattern and motor behaviour remain abnormal. From one month on the unit activities disturbances and the motor deficiencies stabilize. The hypothesis is advanced that Purkinje cell inhibition on their target neurones, which increases during the initial period, gradually diminishes during the adaptation time, and then stabilizes to a subnormal state.

Aging↗
PubMed1985

Effect of proteins on availability of zinc. I. Gastrointestinal transit time of casein and whey protein and zinc absorption in weaned rats.

The availability of zinc from isolated casein (CasD) was compared with that from whey protein (WpD) in 23-25 day old rats. The study was designed to show the course of the gastrointestinal transit time of either chyme (radiolabeled by 141Ce as a non-absorbable marker) or zinc (as 65Zn) in groups of 9 to 12 animals each. Animals were killed either 1/4, 1/2, 1, 2, 6, 12 or 24 hours after intragastric intubation of the protein suspensions. Immediately afterwards, intragastric pH was measured and the determination of zinc retention in intestinal tissues and liver as well as in the carcass was performed. 30 and 60 minutes after intubation the intragastric pH of the CasD group was significantly lower than that of the WpD group. The precipitation behaviour of the two protein fractions - compact curd formation by the CasD versus flocculent structure of the WpD - was determining for the pattern of gastric emptying. With the WpD the chyme was emptied according to an exponential function; while the CasD precipitate left the stomach in three distinct phases. With either protein suspension zinc left the stomach ealier than the bulk of the chyme, indicating a partial disintegration of the zinc-protein-complexes. With the WpD, zinc was emptied exponentially, whereas with the CasD a biphasic emptying pattern was found. Ileum was found to be the main zinc absorbing segment, mainly due to the long time of contact with zinc. After 2 and 12 hours zinc retention from the CasD was significantly higher than that from the WpD, however, after 24 hours retention was significantly better from the WpD. From the present study it can be concluded that, for comparison of zinc availability from diets containing different proteins, short-term experiments are not appropriate. Furthermore, it can be supposed that preabsorptive processes in the stomach are crucial for the availability of zinc.

Animals↗
PubMed1985

Localization of acid microclimate along intestinal villi of rat jejunum.

Considering the significance that pH value could have for digestive and absorptive processes, these investigations were aimed at precisely localizing the position of the acid microclimate, i.e., of proton accumulation along the surface of intestinal villi. The determinations were carried out under microscopic control on jejunal segments of rats incubated at 25 degrees C in O2-saturated phosphate buffer (pH 7.4). Specially manufactured antimony microelectrodes (tip diam 50 microns) and calomel reference electrodes were used for pH registration. Highest proton concentration (214-224 nmol/l not equal to pH 6.67-6.65) was found 10-100 microns below the tip of the villus in the zone of digestive and absorptive epithelial cells. Toward the crypt, a steep decrease of proton concentration was registered with alkaline values 200 microns below the villus tip. Toward the bulk phase, the decrease of the proton concentration was moderate due to the existence of the unstirred water layer as an effective diffusion barrier. The pH value of the bulk phase was reached 440 microns over the villus tip, a distance possibly identical to the thickness of the unstirred water layer.

Acid-Base Equilibrium↗
PubMed1985

[Activity of neurons of the red nucleus after destruction of the inferior olive in the rat].

The spontaneous frequency of discharge of the red nucleus neurones has been evaluated in the rat before and after total and bilateral destruction of the inferior olive by 3-acetylpyridine. The suppression of the inferior olive increasing the cerebellar inhibition, produces, as a consequence, a consequence, a disfacilitation of the activity of the red nucleus neurones. The process persists for a few days, then a progressive compensation takes place. A month later the average frequency of discharge is recovered but a normal unit activity and motor behaviour are not restaured.

Animals↗
PubMed1984

[Effective intraluminal concentration of riboflavin and pyridoxine in various intestinal segments of the rat].

The study was designed to determine the intraluminal concentration of riboflavin and pyridoxine in different gastrointestinal segments of rats as a function of time after intragastric application of the vitamins. A semi-liquid diet with 14C-riboflavin and 3H-pyridoxine was delivered by tube. After a period of 30 minutes, 1, 2, 6, 12 or 24 hours, respectively, concentrations of the vitamins were determined by radio-chemical methods in stomach, duodenum, jejunum and ileum. In the duodenum highest concentration of riboflavin (10.4 nmol/l) was reached 2 hours, that of pyridoxine (5.5 nmol/l) 1.5 hours after intubation. In jejunum maximum concentration of both vitamins--4.1 nmol/l riboflavin and 3.0 nmol/l pyridoxine--was found 1.5 hours after tube feeding. As discussed for riboflavin, precise information about the physiologically relevant intraluminal concentration of micro-nutrients in the absorbing intestinal segments is essential, especially if transport mechanisms have to be elucidated.

Animals↗
PubMed1984

Synthesis and antidepressant activity of 4-aryltetrahydrothieno[2,3-c]pyridine derivatives.

A series of substituted 4-aryltetrahydrothieno[2,3-c]pyridines was prepared by acid-catalyzed cyclization of 1-aryl-2-[(2-thienylmethyl)amino]ethanol derivatives. The compounds were examined for their antidepressant activity, as demonstrated by their ability to inhibit the uptake of norepinephrine (NE) and serotonin (5-HT) and to prevent tetrabenazine-induced ptosis (TBZ) in mice. Significant inhibition of both neurotransmitters is observed for several of the tested compounds, while some of them are selective inhibitors of either NE or 5-HT uptake. Optimal activity is associated with the introduction of lipophilic substituents into the 4-position of the phenyl ring and less lipophilic substituents into the 2-position of the thiophene ring (11, 23). Compound 33 bearing substituents in positions 2 and 6 of the phenyl ring is inactive. This might be a consequence of an out of plane conformation of this compound.

Animals↗
PubMed1983

In vitro kinetics of the intestinal transport of riboflavin in rats.

Transmural intestinal transport of riboflavin was studied in a concentration range between 0.033 and 10.0 microM by an in vitro perfusion technique by using everted jejunal segments of rats. The transport was found to have a dual characteristic: at low, i.e., physiologically relevant concentrations, a carrier-mediated saturable component predominated; at higher concentrations this component was increasingly obscured by simple diffusion as the prevailing transport mechanism. The transport constant KT of the saturable component was calculated to be 0.54 microM. The Q10-value was 2.31 for a low concentration (0.322 microM) and 1.44 for a high concentration (10.0 microM) of the substrate. When Na+ was partially replaced by Li+ or choline+ in the media or when ouabain was added to the serosal medium, the saturable component of the transport was completely abolished. The substrate analogue lumiflavin reduced the transport rate of riboflavin at low substrate concentration only. Generally, the results indicate that it is essential to consider the physiologically relevant concentration of micronutrients in studies concerning the mechanism of their intestinal transport.

Animals↗
PubMed1983

Hydrolysis of FMN and FAD by alkaline phosphatase of the intestinal brush-border membrane.

Both FMN and FAD were found to be hydrolysed with saturation kinetics by purified alkaline phosphatase (aPase E.C. 3.1.3.1) as well as by a brush-border membrane preparation (BBMp) from rat jejunum. With aPase the KM-value was 11.0 mmole/l when FMN was applied and 4.4 mmole/l when FAD was used. The apparent KM-values with the BBMp were calculated to be 22.9 mmole/l for FMN and 5.7 mmole/l for FAD as substrates. The BBMp contained FMN- and FAD-hydrolysing activity besides that due to the aPase. Regarding the high phosphatase activities associated with the brush-border membrane, it seems unlikely that FMN and FAD penetrate this membrane without being split. The transmural intestinal transport of 14C-riboflavin was tested in vitro in the presence of non-labelled FMN and FAD. The transport rate of the labelled riboflavin was found to be reduced by the coenzymes. It could be concluded that 14C-riboflavin competed with the non-labelled riboflavin released by the phosphatases for the binding sites of a hypothetical transport carrier.

Alkaline Phosphatase↗