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Biomedical subjects

M Sámel

Publications and source records attributed to M Sámel.

At least 19 recordsLinked to original sources
PubMed1997

[Ethical problems in molecular genetics and their reflection in clinical medicine].

There are at least two groups of issues connected with an impact of a realization of the "Human Genome Project": a) philosophical; b) ethical, which can be divided into four groups: 1) the influence of DNA technologies on everyday applications of bioethical principles; 2) ethical aspects of genetic diversity; 3) ethical aspects of genetic screening; 4) somatic and germ-cell gene therapy; Unlike essential philosophical issues practical realization of issues in question can be largely expressed as only revitalization of old ones and concerns: the principle of justice-equal access and priorities; protection of reproductive choices; disclosure to patients and to relatives at genetic risk (disclosure and exclusion tests); prenatal diagnosis for "mild to moderate" diseases with and without genetic indication-commercialization; insurance policy; non-directive and directive genetic counseling. Maybe there are regional and other differences, but in practice, the main ethical issues are likely to involve screening for genetic risk of common diseases of adult life e.g. hypertension, diabetes, gout, dyslipoproteinemia, genes for premature atherosclerosis, etc. because of the possible direct impact on a patient, an implication for life-insurance, employers and commercial exploitation.

Ethics, Medical↗
PubMed1997

[Relation between levels of essential fatty acids in maternal milk, in maternal blood and in the blood of neonates 1 and 5 days after birth].

BACKGROUND: Linolenic, linoleic, and arachidonic acids as well as other polyunsaturated fatty acids are necessary for health as the precursors of eicosanoids and for the structure of developing membranes. OBJECTIVES: The aim of the present study was the determination of the level of 11 individual free fatty acids (FFA) in the milk and in the blood of mothers and newborns during the perinatal period. METHODS: In 21 women the FFA was determined in their colostrum as well as in the venous blood at the delivery in the hospital, and then again 5 days later at leaving the hospital. Simultaneously, the blood of newborns was collected as umbilical samples at birth and as venous blood on the 5th day. The study was performed on health term infants and mothers with normal gestational age. RESULTS: The results show a marked increase in total milk FFA as well as in most, but not all, individual FFAs during the followed period of the first 5 days. The values in the milk were always remarkably higher (the increase more than 2 orders) than in the blood. We have found no significant statistical correlation between values in the blood and those in the milk. The concentrations of all very important omega-3 FFAs (which are present in fish oil and in foods of marine fish origin) were always lower in all blood and milk samples in comparison with the levels of omega-6 FFAs (which are prevailing in lipids of our usual nutrition as are margarines and most of commercial oils). CONCLUSIONS: Our findings seem to be very important for preventive medicine and need to study further the relationship of low intake of O3FA to increased incidence of various allergies and other pathological syndromes in children. The very large range of a variance in the values of FFAs in the milk suggests the need of more profound study of the role of the food composition probably during the whole period of pregnancy, mainly as to the type of lipid composition. (Tab. 1, Fig. 6, Ref. 24.)

Fatty Acids, Nonesterified↗
PubMed1994

[Ethical principles in working with live animals and human fetal tissue in biomedical research].

The regulations for the protection of experimental animals which are suggested are based on internationally recognized ethical principles. The research institutions should establish and maintain appropriate policies and procedures to ensure the human care and use of live vertebrate animals. Recent developments in the use of human fetal tissue for therapeutical transplantations represent some serious ethical problems. Proposals for the ethical use of human fetal tissues are suggested. (Ref. 8).

Animal Welfare↗
PubMed1994

Development of brown adipose tissue in the rat and thyroxine administration influence.

The role of the thyroid hormone in the activity of brown adipose tissue (BAT) is in most papers underestimated and it is the noradrenaline which is considered as the main regulator. The aim of the presented experiments was the study of the effect of 2 or 3 administrations of thyroxine (T4) applied to young rats of different age on the weight of BAT. T4 was injected in relatively large doses, i.e. 1 microgram/gram BW/day dissolved in 0.005 mmol NaOH intraperitoneally. Changes in T4 injected animals were compared with their litter-mate control, which were injected with solvents. In control animals the relative weight in mg/100 g BW was significantly higher during the entire first postnatal month in comparison with adult animals. Three administrations of T4 caused significant increase in relative as well as in absolute weight in all age groups. The difference was significant in dry tissue also. When the change was expressed in percentage the greatest effect of T4 was found in 15- and 19-day-old animals. Another experiment followed the effect of only two injections of T4 on BAT to animals of 7 different litters but of the same age, i.e. on day 5 and 6 and euthanized as 7-day-old. In all litters the increase after T4 treatment was significant; the increase in % ranged from 20 to 40% and was influenced by the level in controls. The relative weight in control animals ranged from 620 to 920 mg/100 g BW. This between-litter variance is greater than the effect of T4.(ABSTRACT TRUNCATED AT 250 WORDS)

Adipose Tissue, Brown↗
PubMed1994

[Changes in cholesterol and triacylglycerol serum levels in rats during postnatal ontogenesis].

In the serum of young normal rats during the first two months of life the concentrations of triacylglycerols (TG) and of cholesterol (CH) were determined. Low values in both studied parameters found in newborn animals were followed by a marked increase during the first week of life. In comparison with adult animals high values remained during the first five weeks of life. The results are discussed with regard to the high intake of lipids by milk during the period of sucking, as well as from the point of possible mobilization of tissue lipid stores because of the similar trend in the ontogenetic expression of the gene coding the hormone-sensitive lipase (HSL). On the basis of evaluation of the analytical as well as biological variance it was found, that for the level of 50% of confidentiality the serum concentrations of cholesterol should be in the range X +/- 0.26 mmol/l. For the level of 95% the range of values is X +/- 0.67 mmol/l. It is suggested that these results could be used as reference values for serum lipids in the rat during ontogenesis. (Fig. 1, Ref. 21.)

Aging↗
PubMed1994

[Short-term administration of increasing doses of thyroxine has a different effect on serum lipids in male rats and in female rats].

The effects of short-term administration of thyroxine (T4) on serum levels of cholesterol, HDL-cholesterol and triacylglycerols were studied on young adult rats. T4 was injected in three different doses, i.e. 125, 250 and 500 micrograms for four days. The results show significant sexual differences. T4 caused a significant decrease in HDL-cholesterol levels in both sexes. The concentration of cholesterol and triacylglycerol decreased only in males, namely after injections of the highest dose of T4. In females the T4 injections caused no effect in the investigated parameters. It is concluded, that also in short-term applications of hormones, the sex may significantly change the results. Presented results support the latest views on specific interrelationship between thyroid hormone and HDL in comparison with other types of LP. (Tab. 2, Ref. 16.).

Animals↗
PubMed1994

The development of lipid metabolism. Effect of short-term application of thyroxine on the level of fatty acids and albumin in serum during ontogenesis in rat.

In young rats of different age the effect of short-term administration of thyroxine (T4) on the level of 6 FFA was determined. The concentration of FFA was expressed in mmol/l as well as the molar ratio to serum albumin. The results show that the level of the total FFA and the ratio of saturated to unsaturated (S/U) FFA are high in control animals till the age of 21 days in comparison with adult animals. Administration of T4 caused marked increase in the total FFA in the youngest age group (8-day-old) and the effect increased with age. Differences in the trend of changes in individual FFA were found. In the concentration of myristic acid (C 14:0) a significant increase was found only till the age of 16 days; in the case of palmit-oleic acid the increase was significant in all age groups. T4 caused no significant changes in the values of stearic acid (18:0). When the data were expressed in terms of the molar ratio FFA/albumin, the changes were more pronounced. The peak values found in 16-day-old animals were 33.9 +/- 0.75; they represent a 2-times higher supply of FFA to tissues in comparison with control animals. In this study it was also found that the concentration of serum albumin in newborn animals is low and represents just 57% of adult values. The short-term application of T4 caused no changes in the concentration of serum albumin. The mechanism of T4 action on FFA during ontogenesis was not explained in this study.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

The development of lipid metabolism. Changes in the level of fatty acids in serum during postnatal ontogenesis in the rat.

In young rats of 5 different age groups the spectrum (per cent) of 6 FFA was determined. The results show, that palmitic acid (C16:0) represents the main FFA in all age groups; at the end of the first week forms nearly 50 per cent. In adult animals (8-week-old) values decreased to 26 per cent. Similarly, the myristic acid (C14:0) was found highest in suckling animals (10 per cent) and decreased with age. The ratio of saturated to unsaturated FA (S/U) decreased with age. In other animals of 7 different age groups the concentration of total and of individual FFA was investigated. The results were expressed in nmol.l-1. Results showed, that the total concentration of FFA during the first postnatal month is nearly 2-times higher than in adults. The ratio of S/U FFA decreased from 1.81 to 0.85. The concentrations of individual FFA showed different age-dependent trend. Myristic and stearic acids (C14:0 and 18:0) increased with age till the 4th week. The concentrations of palmitic, oleic and linoleic acids were high during the first 3 weeks of age and decreased after weaning. The concentration of palmitate-oleic acid (C16:1) was lowest in all age groups as well as that of palmitic (C 16:0) was always the highest. These results show, that changes in concentration of individual FFA with age are not dependent only on the intake of the milk. (Tab. 3, Fig. 1, Ref. 8).

Aging↗
PubMed1993

[The effect of age and thyroxine on lipogenesis during ontogeny. Activity of malic enzyme].

In young rats of different ages of postnatal development the effect of short-term administration of thyroxine (T4) on the activity of malic enzyme (ME) was studied in brown adipose tissue (BAT), liver, heart and kidney. Thyroxine was injected in a dose sufficient to saturate all receptor sites, i.e. 1 microgram per 1 gram of B.W. during 3 consecutive days. The highest activities of ME were found in BAT. An increase in enzyme activities with age was observed in all tissues studied in control animals. Injections of T4 increased the activity od ME in the liver; in BAT a significant increase was found only the younger age group (6 days). In older animals (40 days) with high values in BAT of controls no further increase induced by T4 was observed. In the kidney as well as in the heart no significant changes were found after T4 administration. It is concluded that in developing animals BAT may play a more important role in lipid synthesis than considered so far. (Fig. 1, Ref. 7.)

Adipose Tissue, Brown↗
PubMed1993

[Molecular medicine].

The introduction of new methods into medicine, such as recombinant DNA, production of monoclonal antibodies, and particularly polymerase chain reactions, yielded much knowledge and information in fields like preventive medicine (prenatal screening), reproduction strategies (preimplantation diagnosis of genetic defects), molecular diagnosis (oncological and infectious diseases), gene therapy, etc. In many areas the practical use of these sophisticated approaches has become technically feasible yet due to the high cost involved it is still limited. The introduction of some screening programs will be associated with ethical problems of serious impact. To date we can already establish presymptomatic diagnosis of some progressive diseases for which however no therapy is available. Potential abuse of confidential genetic information as well as the possibilities of using gene therapy for "corrective eugenics" are loaded with serious ethical problems. Prospective doctors have to be prepared for this situation in the course of undergraduate studies of medicine. (Ref. 11.)

Abortion, Eugenic↗
PubMed1989

Comparison of indirect and direct methods for determination of sinoatrial conduction time.

We have performed an electrophysiologic study (EPS) in 18 subjects (mean age 21 +/- 17 years) with normal sinus node function (group A) and in 15 patients (mean age 43 +/- 26 years) with sinus node dysfunction (group B). Three extrastimulus methods (both Strauss and Kirkorian methods and our modification of the extrastimulus method) were carried out in 31 patients of both groups and sinoatrial conduction times (SACTSTR, SACTKIR,SACTMOD) could be estimated in 27 of them. SACT by the Narula method (SACTNAR) was assessed in 25 patients of both groups. Sinus node electrograms (SNEs) were attempted in 22 patients and were obtained in 17 of them. Among the indirect methods, by comparison with SACTSTR in group A the best correlation was for SACTMOD (r = 0.81) and the weakest for SACTKIR (r = 0.67); there was no significant difference between SACTs estimated by Strauss and other methods. In group B the weakest correlation was also for SACTKIR (r = 0.68), whereas the correlations for both SACTMOD and SACTNAR were similar (r = 0.72 and r = 0.74, respectively); in this group SACT was significantly underestimated only by the Kirkorian method (P less than 0.01; sensitivity of 45%). By our method sensitivity was 82%, similar to both the Strauss and Narula methods (92 and 92%, respectively). By comparison of indirect methods with the direct measurement of SACT we have found similar good correlations for the Strauss, our own, and the Narula methods in group A (r = 0.81, r = 0.75, r = 0.79, respectively) and in group B (r = 0.81, r = 0.86, and r = 0.72, respectively); here too the weakest correlation was, in both groups, for the Kirkorian method (r = 0.67, and r = 0.68, respectively). The SACT in group B was the more significantly underestimated (P less than 0.001). Significant underestimation of SACT occurred also by our method and the Strauss method (P less than 0.01, and P less than 0.001, respectively), whereas the Narula method did not significantly underestimate the directly measured SACT. From the SNEs after atrial pacing we have shown the limitation of the Kirkorian method and observed the conspicuous beat-to-beat variability of SACTdirect' as the possible explanation of chaotic pattern of return cycles by the extrastimulus methods in some patients of group B.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗
PubMed1989

[Kinetics of thyroxine in ontogenesis studies using the metabolism of radiothyroxine].

Radiothyroxine turnover rate was studied postnatally in 9, 18, and 35 day old rats in various intervals during 24 hours after intrajugular injection. Value of fractional turnover rate indicated higher thyroid activity in 18 day old rats than in those aged 9 or 35 days. These results support our previous conclusions on the maturation of thyroidal regulatory mechanisms in this period of development which were based on the rate of radioiodine uptake and changes in serum thyroxine concentrations. In another series of animals, the distribution of radiothyroxine in comparison with distribution of radioiodide was studied 4 hours after intrajugular injection on days 8, 12, 16, 20, 24, and 30 of postnatal development. In case of hormone distribution, all values in the brain, liver, kidney, intestine, and serum were much higher in young animals than in adult 60 day old rats. Particularly, in the brain up to 16th day, the concentration of T4 was six times higher than in adult animals. The highest percentage of the injected radiothyroxine dose was found in the liver, intestine and stomach, total values in these organs exhibited a progressive increase from 20% on day 8 to 50% on day 24. When compared with litter-mates injected with inorganic radioiodide, the radioactivity in animals treated with hormone was in most organs markedly higher. The opposite results were found only in the stomach, i.e. the uptake of iodide exceeded the uptake of hormone. These results suggests, that differences between age groups are not due by differences in vascularity and although indirectly they may be considered as reflecting changes in size of thyroxine binding sites.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗
PubMed1984

The effects of open heart surgery on growth hormone, cortisol and insulin levels in man. Hormone levels during open heart surgery.

Plasma growth hormone, cortisol, insulin and blood glucose concentrations were measured intra- and postoperatively in ten patients who underwent open heart surgery with moderate hypothermia. Diazepam-ketamine anaesthesia for 10-20 min failed to precipitate any significant alterations in the levels of measured hormones and blood glucose. In the pre-bypass period of surgery, an increase in cortisol and a slight elevation in growth hormone levels was observed; insulin level showed no change in spite of marked hyperglycaemia. The bypass period, including hypothermia and haemodilution, was accompanied by unchanged cortisol and elevated growth hormone levels, while insulin demonstrated a slight rise which did not correspond with the degree of hyperglycaemia. The post-bypass period with rewarming the restoring spontaneous circulation was characterized by further marked increase in cortisol and growth hormone levels and, in spite of decreasing levels of blood glucose, by a paradoxical elevation in plasma insulin. It is suggested that hypothermia, haemodilution, reduced tissue perfusion affecting endocrine glands, as well as denaturation of some hormones in the oxygenator, participate in the moderate endocrine response, disproportionate to the stress of cardiopulmonary bypass surgery. The rise in hormone levels on terminating bypass seems to be dependent on the improved blood flow to endocrine glands due to recovered spontaneous circulation, rewarming and, as for insulin, presumably even on the reduced inhibitory effect of catecholamines.

Adolescent↗
PubMed1983

Venepuncture, catheterization and failure to position correctly during central venous cannulation.

The authors analyse the incidence of puncture, catheterization and failures of positioning in a series of 420 central venous catheterizations performed in 388 patients, using six transcutaneous approaches: supraclavicular and infraclavicular subclavian, external and internal transjugular, antecubital and brachiocephalic. Puncture failures were recorded at 7.9% per 36 failures from 456 attempts, catheterization failures at 5.8% per 26 failures from 446 attempts, and misplacements at a rate of 5.7% per 23 misplacements during 420 catheterizations. The results show that, in respect of puncture, catheterization and success of positioning, the supraclavicular subclavian approach may be recommended preferentially. The internal jugular, brachiocephalic and infraclavicular subclavian approaches are also advantageous. A high rate of failures and misplacements was recorded in the antecubital and external jugular groups. The antecubital veins, however, should be reserved for orthopnoeic sitting patients, the success rate being significantly increased if the patients are sitting.

Adolescent↗
PubMed1983

Surgical, infectious and thromboembolic complications of central venous catheterization.

The authors have analysed the incidence of specific complications in a series of 420 intracaval catheters placed in 388 patients, using six transcutaneous puncture techniques: supraclavicular and infraclavicular subclavian, external and internal jugular, antecubital and brachiocephalic approaches. Strict and moderate criteria were used to evaluate the frequency of complications. Using strict criteria, the lowest rate of surgical complications (5%) was found with the antecubital and external jugular approach, followed by infraclavicular (6.7%) and supraclavicular (9.3%) subclavian techniques; the highest rate was seen with internal jugular (10%) and brachiocephalic (15%) routes. As to inflammatory and infectious complications, the sequence was as follows: brachiocephalic (2.5%), infraclavicular (4.4%) and supraclavicular (5.3%) subclavian, and internal jugular (7%) veins; a 10% incidence was associated with external jugular and antecubital techniques. Manifest thromboembolic complications were observed only in the brachiocephalic and antecubital groups (2.5% and 10%, respectively), the overall incidence of pulmonary embolism being 0.2%. None of the approaches used can be recommended as an exclusive method of choice. The risks of central venous catheterization should be minimalized by adherence to strict principles of placing as well as care of the indwelling intravenous catheters.

Adolescent↗