[Quality of the performance of clinical laboratories]. / A klinikai laboratóriumok teljesítményének minósége.

The quality performance of clinical laboratories plays a basic role in the quality and effectiveness of health care. The reliability of laboratory tests, however, depends on the quality assurance system existing in the working place, which comprises not only the analytical activities but includes all preventive measures and their regular control in connection with the preanalytical phase, as well as the plausibility control and interpretation of results. The external quality assessment of laboratory work gives information about the systematic errors existing between results of different laboratories, and it helps to discover rough errors of either random or systematic origin. The external quality assessment of medical laboratories has its beginning in early 1970's in Hungary and since 1975 it is organized continuously by the National Institute. In recent years, the external quality assessment of laboratories is performed in cooperation and support of the INSTAND e.V./WHO Collaborating Center (Düsseldorf). The paper surveys the quality performance of laboratories in routine clinical chemistry, haematology, blood-coagulation, hormone and blood-gas analysis. Moreover, the evaluation of results on the basis of reference and assigned values measured in the reference laboratories and according to the statistical error of results of participants is also discussed. Further improvement in the quality performance of health laboratory service needs the introduction of unified quality system which includes details of all elements of knowledges and technical activities necessary to fulfill requirement of reliable and effective laboratory work.

Effects of glucocorticoid treatment of the carbonic anhydrase activity of brain tissue in the early postnatal age in the rat.

The carbonic anhydrase activity in the brain tissue shows a considerable increase with proceeding gliogenesis during the first three postnatal weeks in the rat. The administration of 10 to 30 micrograms corticosterone or 5 to 10 micrograms dexamethasone per g body weight to 3-day old rats produced a marked acceleration in maturation of enzyme activity in the neocortex and hippocampus. The noradrenaline-induced stimulation of enzyme activity under in vitro conditions was also enhanced in corticosterone pretreated rats. There was no difference between the influence of noradrenaline and cAMP on stimulation of enzyme activity in either control or glucocorticoid-pretreated rats. In contrast to the corticosterone, the pretreatment with dexamethasone failed to stimulate the noradrenaline or cAMP effects on enzyme activity which may be due to differences in receptor-mediated responses for glucocorticoids. The glucocorticoid-induced acceleration of enzyme activity in the early postnatal period may be attributed to an enhanced development of glial elements.

Effects of ACTH 1-24 on hydrolysis of beta-casomorphin-4-nitroanilide in brain homogenates in vivo and in vitro.

Administration of ACTH 1-24 to 3-10 days old rats produced a significant decrease in hydrolysis of beta-casomorphin-4-nitroanilide (beta-CM-4NA) in the cytosolic fraction of brain homogenate in the first three hours after injection. Corticosterone treatment did not modify the hydrolysis of the substrate. ACTH 1-24 but not ACTH 4-10, Met-enkephalin or Leuenkephalin given to the brain homogenate resulted in a dose-dependent decrease in liberation of 4NA from beta-CM-4NA. Kinetic data suggest competitive inhibition of ACTH molecule on hydrolysis of beta-CMA-4NA. The ACTH treatment, however, did not influence the hydrolysis of Pro-Gly-4NA or Pro-Pro-4NA in the brain homogenate in vitro.

[Maternal behavior after the administration of morphine or naloxone to pregnant female rats and the pain sensitivity and brain mu-opioid receptors in the progeny]. / Materinskoe povedenie posle vvedeniia beremennym samkam krys morfiia i naloksona, bolevaia chuvstvitel'nost' i miu-opioidnye retseptory mozga potomkov.

Morphine or naloxone injected twice a day (10 mg/kg/day) to rat females from 15 to 18 days of gestation had no effect on their litter size or body weight of pups. Time necessary for the female to bring pups into the nest from the opposite end of the cage, that is a characteristic of maternal care and negatively correlated with the mean body weight of the pup in the litter, did not change after treatment with drugs during gestation. Newborns treated with mu-opioid receptor ligands during intrauterine development had an elevated number of 3H-naloxone binding sites in the brain. However, the number of 3H-naloxone binding sites on the 9 and 16 days of life, as well as pain thresholds under electric stimulation of the tail at a month age were equal in these rats and offsprings of the intact or saline treated mothers.

Effects of systemic and intracerebral administration of glucose oxidase on the blood sugar level in rats.

Intravenous administration of 10 to 40 U/g b.w. glucose oxidase produced hypoglycaemia in a dose-dependent manner. The enzyme-induced drop of the blood sugar level was associated with significant rise in serum potassium and the concentration of free fatty acids. Intracerebral application of glucose oxidase through chronically implanted cannula into the ventromedial, lateral hypothalamus, preoptic region and amygdaloid complex of nuclei failed to change the blood sugar level, although a moderate increase of the free fatty acids and corticosterone concentrations occurred. The local application of enzyme in the locus coeruleus region led to a significant rise of the blood sugar concentration. The observations suggest the sensitivity of brainstem catecholaminergic neuronal system to hypoglycaemia.

[Quality assurance in clinical laboratory diagnosis]. / Minöségbiztosítás a klinikai laboratóriumi diagnosztikában.

Both the internal and the external quality controls are necessary to achieve reliable and comparable laboratory tests. The internal quality control includes preanalytical, analytical and postanalytical checking of factors to eliminate all interferences of laboratory tests. The use of reliable methods which result in a good accuracy and precision, however, can provide results which are not comparable to the results of other laboratories. The role of the external quality control is to check differences between the laboratories and to make the results as comparable as possible. The accuracy and precision of Hungarian laboratories improved during the past decade which can be attributed to the better technical conditions, on the one hand, and to the regular internal and external quality control, on the other hand. An increasing number of the small laboratories, mostly in the service of general practitioners, are unable to perform the same quality of laboratory tests as that of the central laboratories, since their technical conditions are old-fashioned and inadequate to use up-to-date methods. The urgency of improvement in technical condition of small laboratories is obvious from both professional and economical reasons.

Changes of enzyme activity in T-cells during induced maternal behaviour in rats.

Continuous exposure to foster pups elicits specific behavioural patterns in adult naive female or male rats. The first exposure induces active avoidance of young. By day 2 or 3 adults show neutral behaviour. Next day complete maternal behaviour begins to develop; e.g. retrieving of pups, nursing and crouching. The avoidance reaction activates stress mechanisms, and the developed maternal behaviour is associated with moderate prolactin release. The question is raised whether pup-induced catecholamine and prolactin release is able to alter enzyme activity in T-cells. Using Arg-Pro-; Leu-Pro; and Pro-Pro-4-nitroanilide as substrates the activity of a marker enzyme dipeptidyl peptidase IV, DP IV, EC. 3.4.14.5., was measured in T-cell suspension prepared from the thymi of adrenalectomized female and male Wistar rats. We found that changes of DP IV activity during the pup-induced avoidance phase could be prevented by propranolol pretreatment indicating the role of catecholamines in this phenomenon. Prolactin released during artificial maternal behaviour in female rats resulted in an elevation of DP IV activity which failed to develop, if they were given daily injections of bromocriptine or apomorphine. It is concluded that pup-exposure is the most physiological way to influence hormonal mechanisms and immune functions, which are highly responsive to sensory stimuli.

Dipeptidyl peptidase IV (DP IV) and superoxide dismutase activity in thymus-derived lymphocytes: effects of inhibitory peptides and Zn2+ in vitro.

DP IV and superoxide dismutase (SOD) activity in thymus-derived lymphocytes of rats was assayed in vitro. The DP IV activity was measured fluorimetrically by hydrolysis of Leu-Pro-AMC, and the SOD activity by the inhibition of autooxidation of L-adrenaline. In order of their competitive inhibitory potency the following peptides were tested against DP IV and SOD activity: Ile-Pro-Ile (diprotin A), Val-Pro-Leu (diprotin B), Ile-Pro, Leu-Pro, Val-Pro, Tyr-D--Ala-Ala-Pro, Phe-Pro, Tyr-Pro, Ala-Ala-Pro and Gly-Pro. The peptides, in the order of their potency against DP IV, were effective to inhibit the SOD activity in T lymphocytes. Zn2+ ions exerted an inhibition on both DP IV and SOD activity in a near equimolar concentration. The involvement of Zn2+ as well as the peptides liberated by hydrolysis of polypeptides in regulation of cell-mediated immune responses has been discussed.

Adenosine and pituitary-adrenocortical axis activity in the rat.

As shown by an increase in plasma corticosterone concentrations, adenosine administration stimulated pituitary-adrenocortical activity. This effect was prevented by dexamethasone (2 mg/kg i.p.). Added in vitro, adenosine reduced both adrenal basal and adrenocorticotropic hormone (ACTH)-stimulated corticosterone release, while it stimulated pituitary ACTH release. This ACTH response was blocked by dexamethasone but not by Tyr-somatostatin. Restraint stress increased adenosine content in the anterior pituitary, suggesting its possible involvement in hormonal stress response. Because the effect of adenosine on plasma corticosterone was still present in rats with a pharmacological block of the endogenous corticotropin-releasing factor release, we propose that adenosine is involved in the regulation of adrenocortical secretion at the level of the anterior pituitary and that this role is exerted through an interaction with a stimulatory adenosine receptor.

Changes of dipeptidyl peptidase (DP IV) activity in the T lymphocytes of rats following administration of ACTH, dexamethasone and opiates.

The aim of the work was to study the effect of glucocorticoids, opiates and stressful stimuli on dipeptidyl peptidase IV (DP IV, EC 3.4.14.5) activity of T lymphocytes prepared from the thymus of intact and adrenalectomized rats. Four week old male rats of Wistar strain were used. The in vivo administration of ACTH, dexamethasone and morphine treatment resulted in an increase of DP IV activity in the cell suspension. In adrenalectomized rats ACTH treatment failed to modify the enzyme activity, however, pain or emotional stress resulted in an elevated DP IV activity. Morphine and D-Met2-Pro5-enkephalinamide resulted in a dose dependent activation of DP IV in T cells, an effect which could be modified by naloxone pretreatment. Our findings show that DP IV mechanisms in T cells are highly sensitive to exogenous and endogenous steroids, opiates and biologically active substances released in response to stress in rats.

Recent development in hormone research.

A classical distinction between endocrine cells and neurons cannot be accepted without exception. This dichotomy was first challenged by the concept of neurosecretion. Recent observations indicate that hormone synthesis takes place in many extraendocrine tissues since the gene expression for prohormone synthesis seems to be common for all eukaryotes although the secretion of biological active hormone products is limited by posttranslational processing for differentiated cells. Increasing number of data support the view that regulation of pituitary hormone secretion is under multifactorial control in addition to specific signaling molecular effects of hormone-releasing hormones. Such modulators are co-secreted messengers from hypothalamic sources or co-functioning at the pituitary cell level. Multichannel regulation of pituitary tropic hormones appears to be important for understanding the interactions of pharmacological agents with pituitary hormone release, on the one hand, and the modulation of hormone release in pathological conditions, on the other hand. Perinatal transient hazards may induce permanent alterations in adaptive behavior when tested in adult age. Corticosteroid-induced deviation of avoidance behavioral reactions may be opposed by simultaneous administration of ACTH-like peptides. These observations revealed that a balance of the glucocorticoids and ACTH-like peptides in perinatal period basically determine the adaptative reaction of animals in adult age. Immune system may be called as a mobile brain since its tremendous information capacity and its responsiveness to alterations of chemical environmental signals. Recent data support the view that there is a bidirectional communication between the neuro-endocrine adaptational axis and the immune system. Stress hormones can alter the immune response and mononuclear cells produce factors that change the neuroendocrine regulation. In addition to these, prohormones are synthesized in mononuclear cells that may be involved in regulation of signalization between cells and in activation of endocrine system and brain functions.

Age-related changes in adrenocorticoid and opioid receptor capacity of thymus-derived lymphocytes in rats.

The experiments were performed in 4-day, 4-week, and 4-month old rats. The total binding capacity of high affinity receptors for 3H-naloxone and 3H-corticosterone in thymus-derived lymphocytes was measured in vitro. There was no change in the affinity constant of the receptors for the ligands during the life-time mentioned before. The maximal binding capacity for 3H-corticosterone in thymus-derived lymphocytes showed a marked increase in 1-month and 4-month old ages as compared to the values obtained by the end of the first postnatal week. In contrast, the maximal binding capacity of lymphocytes for 3H-naloxone showed a significant decline with age. Changes in the binding capacity for the two ligands refer to changes in composition of of cells within the thymus and to alterations in cell system in sensitivity to either corticosteroids or opioids.

Exocrine pancreatic secretion: effect of subarachnoidal application of cholecystokinin octapeptide in rats.

Administration of cholecystokinin octapeptide (CCK-8) intravenously, or in the subarachnoidal surface of the olfactory lobe in rats, caused an increase in pancreatic protein and amylase secretion. It was observed that for subarachnoidal administration of CCK-8 both protein and amylase outputs were higher than that seen after i.v. injection. This result is consistent with the presence of central CCK receptors which when activated can enhance pancreatic exocrine secretion. The blockade of the effect of CCK by administration of CCK-8-specific antisera proves the specificity of the subarachnoidal CCK-8 stimulation.

Comparative analysis of enzyme activity in human colostrum, milk, and serum.

Changes of enzyme activity in the colostrum, milk, and serum samples of 14 mothers were followed. For the enzyme assay, the colostrum and the milk samples were diluted, 1:10 and 1:5, respectively. The activity of the following enzymes were measured: lactate dehydrogenase (LDH); gammaglutamyl transpeptidase (GGT); aspartate aminotransferase (ASAT); alanine aminotransferase (ALAT); cholinesterase; alkaline, and acid phosphatase. Milk, LDH, ASAT, and ALAT activities did not change during the first four days of lactation, yet were significantly higher than the corresponding activities of serum. The activity of GGT and alkaline and acid phosphatase in milk showed a marked decrease by day 4 postpartum; however, the GGT stayed much higher than that of serum, while the activity of the other two enzymes decreased to the level of the serum. By contrast, as compared to the colostrum, the cholinesterase activity in the breast milk showed a significant increase.

Superoxide dismutase activity in thymus cell suspension: effects of methionine-enkephalin and morphine.

Superoxide dismutase activity of rat thymus-derived cells was studied by the inhibition of L-adrenaline auto-oxidation oxidation in vitro. The incubation of cells in the presence of methionine-enkephalin (Met-Enk) or morphine (2-20.10(-7) M and 2-8.10(-6) M, respectively) was performed in Krebs-bicarbonate buffer at 37 degrees C for 180 min. After a lag period of 30 to 60 min of incubation, both Met-Enk and morphine decreased the inhibitory activity of cell suspension on the adrenaline autooxidation. Naloxone blocked the effects of opioids in near equimolar concentrations. The observations suggest the interaction of opioids on superoxide anion production of T cell lymphocytes.

The effect of indomethacin, ibuprofen and paracetamol on the TRH induced TSH secretion in the rat.

1. The response of TSH to TRH and the TRH content of the hypothalamus, following indomethacin, ibuprofen and paracetamol treatment, was measured in male rats. 2. Daily treatment of indomethacin (3 mg/kg)) for 3 days markedly reduced T4 concentration in the serum, the TRH content of the hypothalmus gland and inhibit Pituitary TSH response to the low T4 level in the blood. 3. Ibuprofen (12 mg/kg) and paracetamol (50 mg/kg) did not influence T4 or TSH levels of the serum nor the TRH content of the hypothalmus. 4. TRH-induced TSH secretion was not influenced by indomethacin, ibuprofen or paracetamol treatment.

Somatostatin-induced inhibition of lipolysis: in vitro studies.

Incubation of epididymal fat tissue slices with somatostatin (SS) led to the inhibition of epinephrine-induced release of free fatty acids (FFA) and glycerol in a dose-dependent manner. The SS administration did not suppress the lipolysis evoked by dibutyryl cAMP. The experimental findings indicate that SS exerts an inhibition of catecholamines-induced lipolysis at the level of adipocytes although the mechanism of action requires further investigations.

Effect of 1-desamino-D-arginine vasopressin, ACTH 4-10 and adrenaline on acquisition of active avoidance response in prenatally ethanol-treated rats.

The acquisition of active avoidance response was studied in 45 to 50-day old rats exposed to ethanol during pregnancy. The offsprings showed no retardation in somatic development although there was a marked deficit in learning of avoidance response. Daily administration of 1-desamino-D-arginine vasopressin (0.1 to 5 micrograms/100 g b.w.), ACTH 4-10 (0.1 to 2 micrograms/100 g b.w.) and adrenaline (0.2 to 2.0 micrograms/100 g b.w.) facilitated the learning performance in a dose-dependent manner. The retention of responding was tested after the interruption of training for 7 days. The prenatally ethanol-exposed rats with DDAVP pretreatment during the 5-day training procedure showed a better performance than that of the vehicle-treated ethanol-exposed rats but they were inferior to the controls. The present data indicate a complexity of biochemical changes due to the prenatal exposure to ethanol and the learning deficit can be modified by either neuropeptides or catecholamines, by such humoral mediators which are known to influence learning behavior and memory consolidation under different experimental conditions and due to different noxious stimuli from noxious stimuli from either external or internal environment.