Studies of blood viscosity with a newly constructed rotational viscometer which operates via a desk top computer

Increasing interest is being shown in blood viscosity and the whole field of haemorheology. This study presents a newly constructed rotational Couette type viscometer which operates via a commercially available desk top computer and a digital plotter. The influence of haematocrit on blood viscosity is shown and the study also presents blood viscosity values of six to eight healthy men at 24 degrees C and 37 degrees C. At 37 degrees C values are shown both at natural haematocrit and at haematocrit 45%.

The profilin--actin complex: further characterization of profilin and studies on the stability of the complex

Two forms of profilin can be isolated from calf spleen profilactin by chromatography on phosphocellulose. They can be distinguished by C-terminal analysis, which suggests that one of them lacks the C-terminal tyrosine and the penultimate glutamine residue. This is confirmed by treatment of profilin (+Tyr) with carboxypeptidase A, which removes the C-terminal tyrosine (rapidly) and the penultimate glutamine residue (slowly), and thereby converts it to the other form as judged by chromatography on phosphocellulose. The two forms of profilin differ also in solubility and in mobility during so-called 'charge shift' electrophoresis, indicating differences in their ability to bind detergents. Recombination studies using profilin with or without a modified C-terminus demonstrated that this part of profilin is relatively unimportant for the interaction with actin. On the other hand, experiments with native and modified actin revealed that the C-terminus of actin is of the utmost importance for the stability of the profilactin complex. Analysis of the u.v. absorbance and far-u.v. circular dichroism spectra of profilin and actin did not reveal any major changes in the conformation of the proteins accompanying the modifications at the C-terminal ends. Finally, it is reported that purified profilactin contains variable amounts of a protein factor which causes an apparent stabilization of profilactin in solution.

Omeprazole provides protection against experimentally induced gastric mucosal lesions

Omeprazole, given orally to rats, protects the gastric mucosa against various necrotizing agents, in doses (ED50 values 12-40 mumol/kg) which inhibit acid secretion. However, the protection is due to reduced acid secretion since omeprazole given intravenously in doses which completely inhibit acid secretion is not protective. The mechanism of the protective effect of omeprazole is unknown, but does not seem to be due to stimulation of the endogenous synthesis of prostaglandins since the effect was not blocked by indomethacin.

Differentiation among inhibitory actions of omeprazole, cimetidine, and SCN- on gastric acid secretion

The action of the substituted benzimidazole omeprazole (H 168/68) was studied in three different in vitro preparations: the isolated guinea pig gastric mucosa, isolated intact and permeable rabbit gastric glands, and hog fundic microsomal membrane vesicles containing H+-K+-ATPase. The effects of omeprazole were compared with those of cimetidine and thiocyanate (SCN-). Under all the conditions studied, cimetidine only counteracted histamine-induced acid secretion, consonant with its H2-receptor antagonism. In contrast, omeprazole and SCN- were found not only to inhibit histamine-induced secretion but also basal acid formation and acid formation induced by dibutyryl cAMP and a high cell medium concentration of K+. Moreover, acid production induced by ATP in permeable gastric glands was antagonized by omeprazole and SCN-, whereas cimetidine was without effect. The interaction pattern of omeprazole and SCN- was differentiated by studies using the weak base antipyrine in the isolated mucosal preparation, where it was found that antipyrine could reverse the inhibition induced by SCN- but not that of omeprazole. Furthermore, omeprazole was found to inhibit the isolated H+-K+-ATPase, whereas cimetidine or SCN- was without effect. In the isolated mucosal preparation omeprazole caused an increase in K+ secretion rates in parallel with the inhibition of acid formation. This was in contrast to what was observed for cimetidine and SCN-, which exhibited no such increased K+ secretion. The results obtained from intact mucosa and isolated glands are in agreement with the ability of omeprazole to inhibit the isolated H+-K+-ATPase and thus provide evidence of a novel mechanism of action for this inhibitor.

Nucleation of actin polymerization from profilactin. Opposite effects of different nuclei

The lag in polymerization of calf spleen profilactin in response to addition of MgCl2 can be overcome by small amounts of spectrin-actin-band 4.1 complex, covalently crosslinked actin oligomers or sonicated F-actin. All of these factors also nucleate polymerization of pure actin. Another nucleator of actin polymerization, villin, delays filaments formation from profilactin. A simple model of the interaction of profilin with actin can explain these apparently conflicting results in terms of the polarity with which actin filaments elongate from the different nuclei.

Pharmacokinetics of parenteral and oral melperone in man

The pharmacokinetics of melperone (Buronil, Ferrosan, Sweden) was studied after administration of various parenteral and oral doses to man. After parenteral administration, the data could be fitted to a two-compartment model, but after oral dosing the distribution phase could not be separated from the elimination phase, and so an one-compartment model gave the best fit. The half-lives were about 3-4 h, except after intramuscular injection, when the half-life was about 6 h. The bioavailability of oral doses was about 60% of the intravenous injection. After the highest oral dose of 100 mg, the pharmacokinetics, expressed as AUC or Cmax, showed non-linearity, possibly due to saturation of the hepatic elimination system.

Pharmacokinetics of bendroflumethiazide after low oral doses

The pharmacokinetics of bendroflumethiazide after oral administration of 1.25, 2.5, and 5.0 mg were studied in nine healthy male volunteers. Bendroflumethiazide was analyzed by GLC after extractive alkylation. After the lowest dose, the plasma concentration, could be followed to 14 hr, and the data were adequately fitted by a one-compartment model; the half-life was 3.1 hr. After the 2.5 and 5.0 mg doses, the plasma concentration was followed for 24 hr, and the data were fitted by a two-compartment model with half-lives of 8.9 hr. The urinary sodium concentration was doubled after bendroflumethiazide intake, but the urinary potassium concentration remained almost constant. The renal clearance of bendroflumethiazide was around 30 ml . min-1.

Pharmacokinetics of propranolol

The pharmacokinetics of propranolol after the administration of 40, 80, and 120 mg p.o. and 10 mg i.v. was studied in nine healthy male volunteers. Propranolol was analyzed after extraction and derivatization by gas-liquid chromatography. A multiexponential curve-stripping program was used for the pharmacokinetic analysis. The volume of distribution was about 6 liters . kg-1, bioavailability around 25%, with a mean terminal half-life of 6 hr. There was no evidence of either dose dependent disposition kinetics or an oral threshold dose. A slight increase in urine volume was observed after propranolol administration.

Metabolism of femoxetine

The metabolism of femoxetine, a serotonin uptake inhibitor, has been investigated in rats, dogs, monkeys, and human subjects using two 14C-femoxetine compounds with labelling in different positions. The metabolic pathways were oxidation (and glucuronidation) and demethylation, both reactions most probably taking place in the liver. Nearly all femoxetine was metabolised, and the same metabolites were found in urine from all four species. Only a small percentage of the radioactivity excreted in the urine was not identified. Rat and dog excreted more N-oxide than monkey and man, while most of the radioactivity (60-100%) in these two species was excreted as two hydroxy metabolites. The metabolic pattern in monkey and man was very similar. About 50% was excreted in these two species as one metabolite, formed by demethylation of a methoxy group. A demethylation of a N-CH3 group formed an active metabolite, norfemoxetine. The excretion of this metabolite in urine from man varied from 0 to 18% of the dose between individuals. Most of the radioactivity was excreted with the faeces in rat and dog, while monkey and man excreted most of the radioactivity in urine. This difference in excretion route might be explained by the difference in the metabolite pattern. No dose dependency was observed in any of the three animal species investigated.

The effect of melperon on ocular readaptation time, as assessed by a new recording technique

A new simplified technique recording readaptation time after photo stress, RAT, is described. The psychometric properties in terms of internal consistency and retest reliability were tested, and the effect on RAT after intake of melperon at two different dose levels was investigated and correlated to blood plasma levels. The results show that there was a satisfactory consistency of RAT at each occasion but stability over a 1 month period could not be demonstrated. Significantly dose-dependent changes were recorded after intake of melperon but the prolongation of RAT was not significantly correlated to blood plasma levels.

Pharmacokinetics of femoxetine in man

The pharmacokinetics of a structurally new 5HT-uptake inhibitor, femoxetine (FG 4963), with antidepressant properties have been investigated in man using a radioactive as well as a non-labelled substance. A two compartment open model gives a good description of the data, both after oral and intravenous administration. The substance was almost completely absorbed after an oral dose, but only 5-10% reached the systemic circulation due to extensive first pass metabolism. The metabolites had distribution and excretion rates similar to the parent compound. Only a small part (less than 2%) was excreted as femoxetine in the urine. The urinary excretion of the parent compound varied more than a 100-fold depending on the pH of the urine. The urine pH, however, did not influence the plasma concentration of femoxetine. Most of the substance (up to 80%) was eliminated by urinary excretion of metabolites, and only a small part of the radioactive dose was excreted in the faeces (up to 11%). The pharmacokinetic parameters were not found to be dose dependent in the range investigated, but it was not possible to decide whether the bioavailability was dependent on the dose. The variation between subjects was rather large, giving only a limited possibility for prediction of the plasma concentration from one subject to another.

The effect of oxazepam on ocular readaptation time

The readaptation time (RAT) is the interval during which a person exposed to a bright intense light flash cannot perceive a given target. In this study the target used was an optokinetic pattern and the elicited nystagmus (OKN) was registered with electrooculography (EOG), thus giving an objective registration of RAT. Oxazepam in therapeutic doses was given to five healthy subjects and the RAT and serum concentrations of the drug were registered simultaneously at different time intervals. An almost parallel increase of RAT and serum concentration of oxazepam was recorded. This suggests that RAT reflects the depressant effect on the CNS of this drug and it may be used as an objective method of following the clinical effect of a depressant drug as a function of time after intake.

Differences in microtubule stability to colchicine in extracts of guinea pig, rat and rabbit brain

1. Microtubules (MT) from a guinea pig brain 25,000 g supernatant are not depolymerized by colchicine in contrast to MT from similar preparations of rat and rabbit. 2. The colchicine-stability was lost if the guinea pig brain homogenate was centrifuged at a higher g-level, further purified or if only the grey matter was used. 3. The association constant of colchicine to tubulin did not differ between a stable and a labile guinea pig brain preparation. 4. The GTP-hydrolysis was higher in the guinea pig preparation containing stable MT, than in the preparation containing labile MT. Additional GTP added to the polymerized MT before colchicine exposure, labilized the MT. Preincubation with NaF decreased the GTP-hydrolysis and caused a colchicine depolymerization. 5. The results indicate species differences in colchicine sensitivity of in vitro polymerized MT, probably depending on differences in GTP-hydrolysis.

Tocopherol and local X-ray irradiation of two transplantable rat tumours

The influence of tocopherol in an intramuscular dose of 5 mg/100 g body wt. on the effect of local X-ray irradiation of 2 intramuscularly transplanted tumours in the rat was studied. A significantly enhanced effect of irradiation by tocopherol was found, in contrast to the tumour radioprotecting effect with large doses of tocopherol earlier described in literature.

Effects of barbiturates on ultrastructure and polymerization of microtubules in vitro

Barbiturates were examined for in vitro effects on ultrastructure of the frog sciatic system and polymerization of microtubules (MT) in a brain supernatant. Exposure for 5-17 h to 2.0 mM barbiturates caused a considerable loss of MT in ganglionic cell bodies and sciatic axons. This was mostly followed by a proliferation of 10 nm filaments. Under similar conditions treatment with 1 mM NaCN or 0.1 mM 2,4-DNP did not change the number or ultrastructure of MT and filaments. Eight barbiturates, varying in binding ratios to serum albumin and partition coefficients, were tested for effects on polymerization of MT using viscometry. Inhibitory effects were found which correlated with their reported ability to bind to albumin and brain fractions. Dimethylsulphoxide and ethanol were used as solvents for some of the barbiturates. These solvents at 1% had stabilizing effects on MT. The present results are discussed in relation to previous findings of inhibition of rapid axonal transport in vitro in the frog sciatic system by barbiturates.

Plasma level and broncholytic effect of choline theophyllinate after a single dose of a press-coated tablet formulation

The broncholytic effect and plasma concentrations of theophylline in 10 asthmatic patients were studied for 8 hours after a single dose of 600 mg choline theophyllinate in press-coated 200 mg tablets. Therapeutic concentrations of theophylline were rapidly achieved and the plasma peak averaged 10.4 mug/ml after 2 hours. The broncholytic effect was closely related to the plasma level of theophylline. The largest change was in FEV1, which was significantly increased 1 to 6 hours after the dose. No patient complained of adverse effects. A theophylline concentration of 7 mug/ml plasma was adequate for a broncholytic effect, but a higher level was required for a maximal response. The results provide a basis for further studies to establish a dosage schedule suitable for prolonged therapy.

Plasma theophylline level and ventilatory function in chronic obstructive pulmonary disease during prolonged oral treatment with choline theophyllinate

Plasma levels of theophylline and broncholytic activity have been studied in 12 patients with chronic obstructive pulmonary disease during prolonged oral treatment with choline theophyllinate, administered as a press-coated tablet (BrondaxinR). The plasma levels determined immediately before and 80 minutes after each dose showed very good agreement with those calculated on the basis of data from a previous single dose study. The plasma concentration and improvement in ventilatory function were closely correlated throughout the 48 hours of the study. A tendency towards further reduction of bronchial obstruction was observed during the second day, despite essentially unchanged plasma levels of theophylline. The results provide a rational basis for determination of an optimal dose schedule for oral treatment with choline theophyllinate to reduce the symptoms of obstructive bronchial disease.

Hypertension, asymmetric renal parenchymal defect, sterile urine, and high E. coli antibody titre

During an 11-year period four children were seen with asymmetric renal parenchymal reduction, arterial hypertension, and sterile urine. The history and radio-logical or histological findings, or both, were consistent with "abacterial pyelonephritis" induced by bacterial infection in early childhood. All four had raised antibody titres to Escherichia coli. Three possibilities may explain the high antibody titres and insidious course of the renal damage-the presence of bacterial variants or amorphous bacterial antigen in the kidneys or the fact that because of cross-reactivity between certain E. coli O antigens and renal tissue the "E. coli antibodies" were, in fact, autoantibodies.

Effect of bis(p-hydroxyphenyl)-cyclohexylidenemethane (F6060) on the conversion of pregnenolone to delta 4-3-ketosteroids in vitro

Bis(p-hydroxyphenyl)-cyclohexylidenemethane (F6060) is shown to inhibit the in vitro conversion of pregnenolone to progesterone and other Δ4-3-ketosteroids. A 50% inhibition was noted at ∼ 1·10−4 m F6060. Diethylstilboestrol also showed a comparable inhibitory action under the conditions used but 17β-oestradiol did not affect pregnenolone oxidation. Incubations were performed with the 10 000·g supernatant of human ovarian structures; rat ovaries and adrenals. As a substrate 14C-labelled pregnenolone was used. Radioactive conversion products were determined by thin layer chromatography followed by quantitative scanning. The part of reaction products more polar than pregnenolone tended to increase when progesterone production was moderately inhibited by F6060 in human ovarian homogenates.