Search PubMed⌕ Search

Biomedical subjects

J Blahos

Publications and source records attributed to J Blahos.

At least 37 records · Page 2Linked to original sources
PubMed1994

[The effect of aluminum on the structure and metabolism of collagen].

BACKGROUND: Aluminium is considered to be the etiopathogenetic factor in various pathological conditions. It was demonstrated already previously that metals even under conditions in vivo link with collagen structures and influence the protein metabolism. Therefore the authors investigated the effect of aluminium (Al) on collagen and its metabolism. METHODS AND RESULTS: In the described trial aluminium was used as potassium alum, oxalate alum or aluminium chloride. The effect of aluminium was investigated in rats, chick embryos or fibroblast cultures. Using electron microscopy of collagen from the tail tendons, the development of transverse striation following 15 weeks of i.m. Al administration was revealed. At the same time also an increase of temperature of contraction of this collagen by 1.5 to 3.7 degrees C occurred, depending on the Al compound used. On fibroblast cultures an inhibitory effect of Al on their proliferation was found. In chick embryos Al caused a decline of the radioactive hydroxyproline concentration and thus also a reduced collagen synthesis practically in all investigated tissues. Similarly the negative effect of Al was manifested in the incorporation of radioactive glucosamine into proteoglycans of granulation tissue of rats. In cartilaginous collagen enhanced proline hydroxylation caused by Al was observed. CONCLUSIONS: Although it is not possible, with regard to Al chemistry, to make an unequivocal statement on the nature of the compound which causes a particular reaction in biological systems, it may be said, based on the achieved results, that Al has an effect on biological systems due to its bond with collagen structures and by influencing their metabolism.

Aluminum↗
PubMed1993

Studies on the immunomodulatory effects of vitamin D.

The effect of vitamin D on T lymphocytes was investigated using the test of active E-rosettes formation. It was found that: 1. A single oral administration of 600,000 IU of vitamin D2 causes a significant increase in the formation of active E-rosettes. The peak of the increase was found 24 hours after the administration of vitamin D. The formation of E-rosettes the seventh day of the study was comparable with the pre-administration value; 2. Sera with higher concentration of 1,25-dihydroxyvitamin D[1,25(OH)2D] cause a significant increase in the formation of active E-rosettes; 3. Vitamin D is capable of reverting significantly the effect of a serum factor which suppresses the active E-rosettes formation. The authors observed a significant decrease in the effect of trypsin on the lymphocytes after oral administration of a single oral dose of 600,000 IU of vitamin D2. The trypsin-treated lymphocytes regained their lost capacity to bind sheep red blood cells (SRBC) when incubated with AB serum at 37 degrees C for 3 hours. The recovery of E-rosettes-forming capacity of trypsinised lymphocytes considerably increased when the cells were incubated with serum containing higher concentration of 1,25(OH)2D of 600,000 IU of vitamin D2.

Adjuvants, Immunologic↗
PubMed1993

[Hypocalcemic states].

The authors review contemporary knowledge of acute and chronic hypocalcaemia. They mention in more detail the most typical symptom of acute hypocalcaemia, tetany, and emphasize some chronic symptoms of chronic hypocalcaemia. Diagnostic difficulties may arise in particular in epileptic states, hypocalcaemic organic psychosyndrome and cataract. Diagnosis of their hypocalcaemic cause is important from the therapeutic and preventive aspect. The authors mention also states which may cause hypocalcaemia and finally they give an account of therapeutic possibilities in acute and chronic hypocalcaemia. Data from the literature are supplemented by the authors' data on the prevalence, pathogenesis and treatment of hypocalcaemia.

Acute Disease↗
PubMed1992

[Life style risk factors in the etiopathogenesis of osteoporosis and possibilities of prevention].

The prevalence of osteoporosis and its complications, in particular fractures of the femur, are rising and at present special attention is devoted to osteoporosis from the scientific, health and socio-economic aspect. The authors deal with factors of civilization which are involved in the aetiopathogenesis of osteoporosis and its complications and which can be influenced by preventive provisions. These factors which are part of the modern lifestyle comprise physical load, nutritional influences, the influence of toxic substances and drugs. As to nutritional factors the authors pay attention to an adequate calcium intake. They deal in detail also with aluminium intoxications. Attention is also drawn to the possible pathogenetic importance of stress and the authors contemplate on the inclusion of osteoporosis among diseases of civilization.

Calcium, Dietary↗
PubMed1992

[New views on the pathogenesis of osteoporosis].

The author points out new aspects on pathogenetic factors of osteoporosis and its complications. the character of these factors shows that osteoporosis may be considered as a "civilization disease". The incidence of osteoporosis in all civilized countries is increasing and there is a striking resemblance of factors involved in the pathogenesis of osteoporosis to factors involved in the pathogenesis of other "typical civilization diseases" as are cardiovascular diseases or cancer. In more detail are mentioned the roles of physical exercise, nutrition, drugs and various toxic factors.

Humans↗
PubMed1990

[Vitamin D and the immune system].

The authors draw attention to the contemporary broad concept of the vitamin D endocrine system comprising in addition to the gut, bones and kidneys, some other tissues and cells incl. cells of the immune system. They give an account of findings on receptors for the active hormonal metabolite of vitamin D, 1,25-dihydroxycalciferol [1,25(OH)2D], in the cells of the immune system and summarized contemporary ideas on the mechanism of action of 1,25(OH)2D in these cells. They discuss the role of 1,25(OH)2D in non-specific and specific immune processes, and based on data from the literature and results of their own experimental work, they evaluate the possibility to apply the immunoregulating action of vitamin D in clinical practice.

Calcitriol↗
PubMed1990

[Method for the determination of ionized calcium in clinical practice].

The authors give an account of their experience with the problem of assessment of ionized calcium (Ca2+) in clinical work. To assess Ca2+ they use an ICA 2 analyzer of Radiometer Co. Copenhagen which makes it possible to assess concurrently the Ca2+ concentration at a given pH (Ca2+/act. pH), pH and Ca2+ calculated for pH 7.4 (Ca2+/pH 7.4) in capillary and venous blood. The authors confirmed the significant difference between Ca2+/act. pH in venous and capillary blood which is due to the pH and they did not find a significant difference in Ca2+/pH 7.4 in venous and capillary blood. They found that the specimens of capillary blood can be kept in capillaries in the refrigerator at +4 degrees C for four hours without a significant changes of the Ca2+/act.pH level. During subsequent time intervals, i.e. after 24, 48 and 72 hours following collection of the blood sample, there is a significant rise of Ca2+/act.pH due in particular to a significant drop of the pH of the blood samples. The Ca2+/pH 7.4. concentration in capillary blood does not change throughout the 72-hour follow up period. The authors provided also evidence that slight physical strain (30 min. walk on flat ground) does not cause significant changes in the concentration of capillary Ca2+/act.pH nor of Ca2+/pH 7.4 due to the three-minute compression of the arm by the tonometer cuff with a pressure equal to the diastolic blood pressure of the examined subject. The reported results make simpler and more accurate assessment of Ca2+ in clinical and ambulatory practice possible.

Blood Chemical Analysis↗
PubMed1989

Comparison of effects of verapamil, low calcium diet and betamethasone on duodenal calcium absorption efficiency in the chick.

The results indicate that oral administration of verapamil for 2 weeks to the chick is followed by an increase in the efficiency of the duodenal absorption of calcium. In these chicks both a decrease in serum calcium level and an increase in the activity of renal 1 alpha-hydroxylase were observed. The increased calcium absorption following prolonged treatment with verapamil resembles that induced by a low calcium diet. The mechanism of both responses presumably involves an increased production of 1,25-dihydroxyvitamin D3. Both verapamil- and low calcium diet-induced adaptations are capable of overcoming the inhibitory action of betamethasone on intestinal calcium absorption. No effects on calcium absorption were noted if verapamil was administered intraperitoneally which suggests that verapamil exerts its action directly on the intestinal mucosa.

25-Hydroxyvitamin D3 1-alpha-Hydroxylase↗
PubMed1989

Effect of 1,25-dihydroxycholecalciferol on fracture healing and on general posttraumatic skeletal response in rats.

The authors investigated the effect of 1,25-dihydroxycholecalciferol (1,25(OH)2D3) on the local healing process following an artificial fracture of the rat tibia and on the general posttraumatic response of the skeleton to local trauma. The results showed a significant increase in dry weight of fractured tibias as compared with contralateral intact bones which was due to the newly formed callus. 1,25(OH)2D3 significantly increased the weights of tibias which can be explained by its stimulatory effect on callus formation. The uptake of 85Sr into bones resembling the metabolic pathways of calcium was significantly higher in fractured bones as compared with intact ones. 1,25(OH)2D3 significantly reduced the uptake of 85Sr. There was a significantly higher whole body retention of 85Sr in the rats with fractured bones. The administration of 1,25(OH)2D3 significantly reduced the retention of 85Sr in the fractured bone and the concomitant reduction of the whole body retention of 85Sr most likely reflected the increase in intestinal calcium absorption induced by 1,25(OH)2D3 with the consequent decrease in the specific activity of 85Sr administered in a single injection. The general posttraumatic response was reflected by increased dry weight of non-fractured bones. 1,25(OH)2D3 showed a contributory effect on this increase which may indicate that the general response consisted in increased bone formation. The uptake of 85Sr in non-fractured bones was reduced which was also most probably due to a decrease of specific activity of 85Sr. 1,25(OH)2D3 significantly accentuated the reduction of the uptake.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

[The role of aluminum-induced inhibition of the intestinal absorption of calcium in the pathogenesis of aluminum osteopathy].

The aim of the study was to investigate the effect of aluminium on duodenal calcium absorption, the impairment of which can represent a pathogenic factor in the development of aluminium bone lesions. The authors investigated in the chick the effect of Al(OH)3 administered orally and of AlCl3 administered subcutaneously on the duodenal absorption of 47Ca, on serum concentration of calcium, phosphorous, aluminium and 1,25-dihydroxycholecalciferol and on bone morphology. Oral administration of Al(OH)3 for 8, 15, and 22 days was without any significant change. Subcutaneous administration of Al/Cl/3 for 8 day was associated with a significant increase in serum aluminium and 1,25-dihydroxycholecalciferol levels and with a significant decrease of the duodenal absorption of 47Ca. Decreased intestinal absorption of calcium may play a pathogenic role in the development of aluminium osteopathy. Increased serum 1,25-dihydroxycholecalciferol reflects presumably a compensatory mechanism of the lowered calcium absorption.

Aluminum↗
PubMed1987

The effect of verapamil and the calcium ionophore A 23187 on the calcium and phosphorus content of bone.

Verapamil was administered 30 days to adult male rats in a dose of 2 mg/rat per day and the calcium ionophore A 23187 to another group in a dose of 10 micrograms/rat per day. After verapamil, the bone calcium and phosphorus concentration rose significantly compared with the control group, whereas after ionophore A 23187 the bone calcium concentration fell statistically significantly.

Animals↗