Alterations in markers of bone metabolism and adipokines following a 3-month lifestyle intervention induced weight loss in obese prepubertal children

BACKGROUND

Adipokines may influence bone metabolism in children, but this phenomenon is not well understood. Therefore, we studied the relationships between bone markers and adipokines during weight loss in obese children.

MATERIALS AND METHODS

We determined serum leptin, soluble leptin receptor (sOB-R), adiponectin, BALP (bone alkaline phosphatase), CTX-I (C-terminal telopeptide of type I collagen), body composition and bone mineral density (by dual-energy X-ray absorptiometry) in 100 obese prepubertal children before and after 3 months of lifestyle intervention (low-energy diet, physical activity). The control group consisted of 70 non-obese children.

RESULTS

Obese children had higher BALP activity by about 20% (p<0.001) and similar value of CTX-I compared with non-obese children. After weight loss (-0.96 BMI-SDS mean change), the BALP value in obese patients decreased (p<0.001), whereas CTX-I concentration was unchanged. Changes in BALP were positively correlated with changes in BMI (Body Mass Index) (r=0.352, p<0.001), but not associated with adipokine levels. Trend analysis using SDS-BMI subgroups showed that greater reduction of body mass was associated with a greater decrease of BALP (p=0.035) and leptin values (p<0.001), as well as a greater increase of sOB-R (p<0.003).

CONCLUSIONS

Obesity during the prepubertal period is associated with an alteration in the adipokines profile and greater whole-body bone mass as a result of increased bone formation rather than reduced bone resorption. Changes in bone metabolism during lifestyle intervention seem to be related to weight loss but not to changes in adipokines. Further studies should elucidate the influence of long-term therapy on bone mass in childhood.

Serum concentration of biochemical bone turnover markers in vegetarian children

PURPOSE

In general, most children on well-planed vegetarian diets can achieve normal growth and development. However, elimination of animal products from the diet decreases the intake of some essential nutrients, such as calcium and vitamin D, and may influence bone metabolism. This is especially important in childhood and adolescence, when growth and bone turnover are most intensive. The aim of this study was to investigate the serum concentrations of biochemical bone turnover markers in prepubertal vegetarian children.

MATERIAL AND METHODS

We examined 50 children on vegetarian and 50 on omnivorous diets aged 2-10 years. Dietary constituents were analyzed using a local nutritional program. Serum bone formation (OC, BALP) and resorption (CTX) markers were determined by specific enzyme immunoassays (ELISA) and 25-hydroxyvitamin D by the chemiluminescence method (CLIA).

RESULTS

The average daily energetic value and the percentage of energy from protein, fat and carbohydrates in the diets were similar in both groups of children and were within the recommended range. The vegetarian children showed about a two-fold lower daily intake of calcium and vitamin D than their omnivorous counterparts. The level of 25-hydroxyvitamin D in the serum of vegetarian children was also nearly 2-fold lower compared with omnivores. In vegetarians, as compared to non-vegetarians, mean serum concentrations of OC, BALP and CTX were lower by about 20%, 10% and 15%, respectively.

CONCLUSION

Our preliminary results suggest that an inadequate dietary intake of calcium and vitamin D may impair bone turnover rate in vegetarian children. The parameters of bone metabolism should be monitored in these children in order to prevent bone abnormalities.

Osteoprotegerin and C-telopeptide of type I collagen in Polish healthy children and adolescents

PURPOSE

Most metabolic bone diseases are characterized by a disturbances in bone resorption, therefore biochemical markers concerning this process are of special interest. Recently, the novel cytokine osteoprotegerin (OPG), belonging to the tumor necrosis factor receptor family has been established as an endogenous inhibitor of osteoclastogenesis and resorption process. In addition serum C-telopeptide of type I collagen (s-CTX) is one of the resorption markers released into circulation as a result of the osteoclast mediated degradation of type I collagen. However, a clinical application of OPG and s-CTX in children may be difficult by less information of suitable reference data in relation to age, race and sex. The aim of our study was to invastigate serum concentrations of both markers in polish healthy children and adolescents.

MATERIAL AND METHODS

We examined 102 healthy children and adolescents in 6-24 years of age, divided on prepubertal, pubertal and postpubertal groups. OPG and s-CTX were determined by ELISA kits from Biomedica (Austria) and Osteometer (Denmark) respectively.

RESULTS

The highest mean values of OPG were in prepubertal girls (4.64 +/- 0.57 pmol/L) and boys (4.28 +/- 0.86 pmol/L). Next, in older children and adolescents gradually decreased of OPG concentration was observed. We also obtained the decreased of s-CTX concentration in studied children except these in pubertal period. Generally, we obtained significant positive correlation between OPG and s-CTX in all observed groups (n = 102, r = 0.653; p < 0.0001).

CONCLUSIONS

We report the age-related decrease in circulating endogenous OPG during childhood and adolescence. Serum OPG concentration in postpubertal period may be similar to those presented in young adults. Prospective studies are needed to investigate the influence of OPG on bone metabolism in children.

Serum homocysteine, folate, vitamin B12 and total antioxidant status in vegetarian children

PURPOSE

The results of several studies point to the positive role of vegetarian diets in reducing the risk of diabetes, some cancers and cardiovascular diseases. However, exclusion of animal products in vegetarian diets may affect the cobalamin status and cause an elevation of the plasma homocysteine level. The aim of this study was to assess the effect of vegetarian diets on serum concentrations of homocysteine, folate, vitamin B12 and total antioxidant status (TAS) in children.

MATERIAL AND METHODS

The study included 32 vegetarians (including 5 vegans), age 2-10 years. Dietary constituents were analyzed using a local nutritional programme. Serum homocysteine, folate and vitamin B12 were determined with fluorescence and chemiluminescence immunoassays. The concentration of TAS was measured by a colorimetric method.

RESULTS

Average daily energy intake and the percentage of energy from protein, fat and carbohydrates in the diets of the studied children were just above or similar to the recommended amounts. It could be shown that vegetarian diets contain high concentrations of folate. In vegan diets it even exceeds the recommended dietary allowance. Mean daily intake of vitamin B12 in the studied diets was adequate but in vegans was below the recommended range. The serum concentrations of homocysteine, folate, vitamin B12 and TAS in vegetarian children remained within the physiological range.

CONCLUSIONS

The presented data indicate that vegetarian children, contrary to adults, have enough vitamin B12 in their diet (excluding vegans) and normal serum concentrations of homocysteine, folate and vitamin B12. Therefore, in order to prevent deficiencies in the future, close monitoring of vegetarian children (especially on a vegan diet) is important to make sure that they receive adequate quantities of nutrients needed for healthy growth.

Low serum leptin concentration in vegetarian prepubertal children

PURPOSE

Vegetarian diet may play a positive role in reducing risk of several chronic diseases such as diabetes, coronary heart disease and some types of cancer. There are different vegetarian dietary patterns, some of which are nutritionally adequate for children, whereas other may lack some essential nutrients. Leptin, a hormone from adipose tissue plays a key role in the control of body fat stores and energy expenditure. Higher leptin levels were observed in obese subjects and lower in anorectic patients. Recent studies support that diet may be a factor which influences leptin levels. The aim of this study was to investigate serum concentrations of leptin, lipids and apolipoproteins in prepubertal children with two different nutritional habits: vegetarian and omnivorous diet.

MATERIAL AND METHODS

We examined 22 vegetarians and 13 omnivores in age 2-10 years. Serum leptin concentration was determined by immunoenzyme assay (ELISA) and serum lipids were measured by enzymatic and immunoturbidimetric methods.

RESULTS

Average daily dietary energy intake and the percentage of energy from protein, fat and carbohydrates were similar for both groups of children. We observed that in vegetarian diet there is a high rate of fiber nearly twice as high as in omnivorous diet. Vegetarians had lower total cholesterol and HDL- and LDL-cholesterol concentrations than children on traditional mixed diet. There is no significant differences in triglyceride concentration between studied groups. The apolipoproteins levels in vegetarian children were significantly below that of omnivores. The serum concentration of leptin was lower in vegetarians (3.0 +/- 1.1 ng/mL) than in nonvegetarians (5.1 +/- 2.0 ng/mL) (p < 0.01).

CONCLUSIONS

Our results suggest that vegetarian diet may be accompanied by lower serum leptin concentration. Further studies on large group of children are needed for understanding this problem better.

Antioxidant status in erythrocytes of cystic fibrosis children

Activities of superoxide dismutase, catalase and glutathione peroxidase in erythrocytes of cystic fibrosis children were studied in order to estimate the severity of their deficiency. Our results point to increased susceptibility of erythrocytes of cystic fibrosis subjects to oxidative injury and indicate that the antioxidant status of patients should be carefully monitored.

[Level of retinol and beta-carotene in plasma of smoking and non-smoking women]

Cigarette smoking during pregnancy generates many oxidants and free radicals and it has been implicated in cellular damage. Retinol and its provitamin beta-carotene are natural factors protecting cells from damaging influence of free oxygen species. The aim of our study was the assessment of vitamin A and beta-carotene levels in plasma of smoking and non-smoking pregnant women. Assignment the groups was based on the concentration of serum cotinine. In the presented studies the mean level of serum cotinine in smoking pregnant women was 1326 +/- 790 micrograms/l (range 350-1930 micrograms/l). In the group of tobacco abstinents the level of cotinine was in a range of 0-60 micrograms/l. Plasma concentrations of retinol and beta-carotene were measured by high pressure liquid chromatography (HPLC). Plasma level of vitamin A was lowered by 20% and was 1.64 +/- 0.42 mumol/l and 2.06 +/- 0.58 mumol/l in smoking and abstinent groups respectively. Women who smoke during pregnancy also have significantly lower levels of beta-carotene in plasma (1.9 +/- 0.5 mumol/l) than non-smokers (2.4 +/- 0.6 mumol/l; p < 0.001). We have observed that plasma concentration of beta-carotene has decreased since 21 gestation week in smokers while in abstinent group increased during pregnancy. The increase of plasma level of beta-carotene indicates that their physiological requirement is satisfied by standard vitamins supplementation. The reduced concentrations of plasma retinol and beta-carotene suggest that consumption of these antioxidants for neutralization of free radicals present in cigarette smoking is enhanced. The observed changes indicate that vitamins intake in smoking pregnant women should be carefully controlled.

[Serum leptin level in prepubertal children with simple obesity. Part one]

The aim of the study was to determine the serum leptin level and anthropometric indices (body mass index - BMI) in a group of prepubertal children with simple obesity. These parameters were compared with the values characteristic for the group of slim children. The study showed that serum leptin levels were significantly higher in obese children compared with the group of slim children (p<0.0001). There was a positive correlation (r=0.48; p<0.05) between leptin levels and nutritional status indices expressed by BMI. Results of this study suggest that leptin level in the group of children with simple obesity does not have an effect on satiety, on reduction of appetite or on the increment of adipose tissue. The study showed also that hyperleptinemia might be an effect of leptin resistance.

[Selected independent risk factors of atherosclerosis in children as the basis of early detection of premature ischemic heart disease]

This review briefly summarises the scientific evidence for the child's future risk of ischemic heart diseases (IHD). The conventional risk factors such as dyslipidemia, hypertension, diabetes and smoking can not account for all the cases of cardiovascular diseases. Therefore other risk factors such as fibrinogen, homocysteine, paraoxonaze and abnormality in antioxidant defence systems are included. Among the lipids parameters the level of lipoprotein (a) and increased plasma cholesterol, specifically LDL-cholesterol may be used as a marker of family history of IHD and hypercholesterolemia. Additionally, low level of HDL-cholesterol is also related with endothelial dysfunction and increased oxidative stress. It has been hypothesised that free radicals mediate in the development of IHD and that antioxidants play a protective role in prevention of this pathology. Many of the major risk factors can be modified through diet, body mass control, exercise and (if necessary) through pharmacological intervention. Therefore, the efficacious prevention should be related with the early detection of risk factors particularly in children with familial dyslipidemia, hypertension and IHD.

[Homocysteine and some lipid parameters in hypercholesterolemic children]

High serum homocysteine (tHcy) concentration is increasingly recognised as independent risk factor for atherosclerosis, early coronary heart disease (CHD) and other vascular diseases. It has been proved that adult cardiovascular disease begins in childhood. In the presented studies we determined concentrations of homocysteine, lipids and lipoproteins in plasma of hypercholesterolemic and normocholesterolemic children. In hypercholesterolemic children total cholesterol, LDL cholesterol, apolipoprotein B and triglycerides were significantly higher, whereas HDL cholesterol and apolipoprotein A-I were lower in comparison to the control group. Total serum homocysteine in children with positive family history for cardiovascular disease CHD(+) was significantly higher than in the control groups, and in CHD(-) group. It was respectively 7.3 micromol/1 versus 5.45 micromol/l versus 5.21 micromol/l. The results obtained in our study indicate that in hypercholesterolemic children with positive family history for CHD, the concentration of tHcy can be considered as a separate predictive risk factor for premature cardiovascular disease.

Antioxidant status in erythrocytes of cystic fibrosis children

Activities of superoxide dismutase, catalase and glutathione peroxidase in erythrocytes of cystic fibrosis children were studied in order to estimate the severity of their deficiency. Our results point to increased susceptibility of erythrocytes of cystic fibrosis subjects to oxidative injury and indicate that the antioxidant status of patients should be carefully monitored.

[Homocysteine and hyperhomocysteinemia]

This paper reviews the biochemical and physiological data underlying hyperhomocysteinemia. Elevation of plasma homocysteine arises from disrupted of its metabolism (remethylation to methionine and transsulfuration to cystathionine) and is a function of a complex interaction between multiple genetic and environmental factors. Hyperhomocysteinemia, a conditions that recent epidemiological studies have shown to be associated with an increased risk of vascular diseases, may be a equal importance to hypercholesterolemia, hypertension and smoking in etiology of atherosclerosis. Based on the role of folic acid, vitamin B12 and B6 in homocysteine metabolism supplementation with these vitamins in treatment of hyperhomocysteinemia both in cardiovascular diseases and neural tube defects is reviewed.

Extensive and partial protein hydrolysate preterm formulas: the effect on growth rate, protein metabolism indices, and plasma amino acid concentrations

BACKGROUND

The use of protein hydrolysate preterm formulas is restricted because data on their nutritional adequacy are scarce. The authors evaluated the rate of growth and indices of protein metabolism in low-birth weight infants fed extensive and partial protein hydrolysate preterm formula followed for 12 weeks.

METHODS

A total of 61 low-birth weight infants were assigned randomly to receive extensive protein hydrolysate preterm formula (EH: n = 16), partial protein hydrolysate preterm formula (PH: n = 15), and standard preterm formula (SF; n = 15), or were fed their own mother's fortified breast milk (FBM; n = 15). The infants were investigated at study entry, and at 4, 8, and 12 weeks after study entry.

RESULTS

There were no differences with respect to growth rate (weight gain, increments in length and head circumference), urea, albumin, prealbumin, transferrin, and plasma amino acid concentrations (except for tyrosine on a single occasion) according to the degree of hydrolysis. There were also no differences between groups fed hydrolyzed formulas and SF. However, several differences were found when EH and PH were compared with FBM. Weight gain from the entry to 12 weeks, serum urea at 12 weeks, and total plasma essential amino acids at 8 weeks were significantly higher in groups fed EH and PH than in those fed FBM. In addition, valine was significantly higher in groups fed PH (P < 0.05) than in the group fed FBM at 8 and 12 weeks, tyrosine was higher in EH and PH in comparison with FBM at 4 weeks, and in PH versus FBM at 12 weeks after study entry.

CONCLUSIONS

This study suggests that experimental EH and PH are at least nutritionally equivalent to SFs.

Serum homocysteine and lipoprotein (a) concentrations in hypercholesterolemic and normocholesterolemic children

The relationship between lipids, lipoproteins, total homocysteine, and lipoprotein (a) was studied in hypercholesterolemic and normocholesterolemic children. In hypercholesterolemic children, concentrations of total cholesterol, low-density lipoprotein (LDL) cholesterol, apolipoprotein B, and triglycerides were significantly higher compared to levels in controls, whereas concentrations of high-density lipoprotein (HDL) cholesterol and apolipoprotein A-I were lower compared to those in the control group. Total serum homocysteine concentrations in children with a positive family history for cardiovascular disease CHD(+) (7.28 micromol/L) were significantly higher than those in the control group (5.45 micromol/L), and in the group of CHD(-) children (5.25 micromol/L). The median value of lipoprotein (a) in patients was 31.5 mg/dL (range, 11-209 mg/dL) and in the control group, 19 mg/dL (range, 11-95 mg/dL). Concentrations of Lp (a), exceeding 30 mg/dL, were present in 45% of CHD(+) children, in 29% of CHD(-) children, and in only 11% of the control group.

[Selected parameters of antioxidant capacity in renal allograft recipients]

Various oxidant species, oxygen free radicals (OFR) implicated in patients with chronic renal diseases treated with dialysis and after cadaveric renal transplantation. Oxidative stress occurs when free radical generation exceeds antioxidant defence. We therefore examined markers of lipid peroxidation and antioxidant potential in blood (serum, plasma, RBC) of very carefully (clinically and biochemically) selected 102 subjects (56 female and 46 male, mean age 37.5 +/- 7 years). Included were 51 renal allograft recipients (RARs); 15 patients with glomerulopathies (GL); 36 healthy age- and sex-matched volunteers as a control group (C). All RARs were divided into two subgroups: RARs-A (n = 28) were treated with triple drug therapy including cyclosporin A (CsA) and RARs-Z (n = 23) were on double drug regimen: prednisone, azathioprine. Patients with coronary artery disease (CAD), diabetes, serum creatinine concentration > 2.0 mg/dl, acute rejection and infections were excluded. We used several automated assays to estimate: malondialdehyde (MDA); total radical-trapping antioxidant potential (TRAP), glutathione peroxidase (GPx), glutathione (GSH), superoxide dismutase (SOD), catalase (CAT), vit. E and lipid profiles. Patients of RARs-A were found to have significantly elevated triglycerides; cholesterol-LDL; MDA; TRAP and decreased activity of RBC glutathione peroxidase as compared with those of RARs-Z and group C.

IN CONCLUSION

our data show that oxidative stress (with prooxidant effect of CsA partly at least), with reduced in antioxidant potential of defences system is associated with kidney transplantation.

[The role of leptin in human obesity]

The mechanism involved in body mass regulation in humans includes genetic, environmental, and behavioural factors. Human obesity is usually associated with a positive energy balance. Genetic studies in obese mice have revealed the Ob. gene, its products leptin and the leptin receptor to be important factors in the regulation of both appetite and energy expenditure. Leptin is a 16-kilodaltons adipocyte-derived hormone -which circulates in the serum as the free and bound forms. The leptin serum level reflects the amount of energy stored in adipose tissue. Leptin acts through the leptin receptor, -which belongs to the cytokine - receptor family. In rodents as well as in humans, homozygous mutations in genes encoding leptin or the leptin receptor cause early-onset morbid obesity, hyperphagia, and reduced energy expenditure. Recent studies have demonstrated that Ob. gene expression is increased in human obesity. However, mutations of Ob. gene present in the mouse are rare in the human population.

[Levels of lipid peroxides and of some antioxidants in placenta and cord blood of newborns whose mothers smoked during pregnancy]

Cigarette smoking during pregnancy increases the risk of oxidative damage and induces not only intrauterine foetal growth retardation, but also causes disturbances in postnatal growth and development. In the presented studies oxidative damage was estimated through the measurement of lipid peroxides concentration and the level of some antioxidants in placenta and in cord blood of newborns whose mothers smoked during pregnancy. We observed that the concentration of lipid peroxides was higher in cord blood and in placenta tissue (8%) than in the newborns of non-smoking mothers, but the activity of superoxide dismutase and glutathione peroxidase were lower by 20% and 16% respectively. Plasma level of vitamin A (p<0.005), vitamin E (p<0.05), fS-carotene (p< 0.0001) and total plasma antioxidant capacity (p<0.05) were significantly lower in the newborn of smoking than the non-smoking mother group. It is suggested that placental tissue protected the foetus against oxidative stress, but not sufficiently. Antioxidant activities of cord blood may also be insufficient in dismutation of free radicals and their detoxication in order to protect newborns against smoking dependent metabolic disturbances.

[Evaluation of iron status in women with pregnancy complicated by tobacco smoking]

Relatively common iron deficiency in pregnant women is assumed to be enhanced by cigarette smoking. In the presented studies we determined cotinine in serum and urine of 75 pregnant women in order to select groups of smoking women and tobacco abstinence. In the smoking group, a mean concentration of cotinine 1039 +/- 560 mg/L in serum and 1025 +/- 540 mg/L in urine were observed. For assessment of iron status we determined in serum: iron, iron-binding capacity (TIBC), transferrin, transferrin saturation, soluble transferrin receptor and ferritin. In serum of smoking woman in comparison to non smoking, the level of ferritin and transferrin was higher but non significantly. Significant increase of TIBC (p < 0.05) and decrease of transferrin saturation (p < 0.05) was observed. Therefore iron deficiency in transport compartment can not be excluded. The concentration of soluble transferrin receptor was the same in both groups studied. However, in late pregnancy (above 27 week of gestation) ferritin concentration less than 20 mg/L of serum was observed in 70% of smoking and only in 39% of non smoking women (p < 0.05). We concluded that cigarette smoking during pregnancy did not have any effect on the entry of iron-bearing transferrin to cells mediated by soluble transferrin receptor, but affected the level of iron-storage ferritin, which leads to iron deficiency in the storage compartment (ID I).

[Serum tyrosine in children with phenylketonuria and mild hyperphenylalaninemia]

Serum tyrosine concentration, Phe/Tyr scores and psychomotor/mental development scores were analysed in 32 children with phenylketonuria (PKU) and 39 with mild hyperphenylalaninaemia. Observation period included the first 6 years of life. Tendency to tyrosine deficiency was observed; stronger in dietary treated PKU patients than in those with mild hyperphenylalaninaemia. Statistically significant differences between patient groups were found only in 3 and 6 years old children (lower tyrosine values in PKU patients). It was observed that evaluation of Phe/Tyr score value might be usefull in differentiation between PKU and mild hyperphenylalaninaemia. Moreover, the above score may help in the evaluation of hypo- and hyperalimentation state in the course of dietary treatment. The level of tyrosine deficiency in the analysed patient groups did not influence their normal intellectual development.

[Compensatory antioxidant activity in blood of women whose pregnancy is complicated by cigarette smoking]

In pregnancy complicated by the cigarette smoking the risk of oxidative damage depends not only on the amount of physiologically enhanced free oxygen species but may be affected by intoxication with tobacco smoke radicals. In the presented studies oxidative damage was estimated through measurement of lipid peroxidation, level of total antioxidant activity and selected antioxidants in plasma and erythrocytes of non-smoking and smoking pregnant women. No differences were found between those two groups in the level of lipid peroxidation and antioxidant activity. Plasma concentration of vitamin A was lower by 15% in smoking than in non-smoking women but vitamin E level did not change. In erythrocytes of the smoking group, concentration of reduced glutathione was 35% higher than in the non-smoking group but activity of glutathione peroxidase and concentration of vitamin E were the same. The observed changes indicate that protection of erythrocytes against free radicals may be sufficient to prevent lipid peroxidation and may manifest local and adaptive response of metabolism for tobacco smoking by pregnant women.

[Biochemical markers of bone turnover and their use]

Although the clinician's ability to diagnose and monitor bone disease has improved in the past decade, there is still a need for more specific methods of assessing disturbances in bone metabolism. This article presents a review of biochemical bone markers and their practical applications in various disease states. Bone resorption and formation markers are considered to be useful in diagnosis and anticancer treatment of primary osseous tumours and metastatic bone diseases. However, better understanding of cellular and molecular events in the different phases of remodeling seems to be necessary to develop more adequate clinical diagnostic procedures and treatment for bone diseases.

Intraglomerular fibronectin and laminin turn-over in chronically rejected kidney allografts in humans

Chronic rejection is primarily responsible for the late loss of allografted organs and remains an important clinical problem. Chronic rejection in the kidney is characterised by arteriolosclerosis and nephrosclerosis, glomerulonephritis and interstitial fibrosis. Recently, a large number of studies have indicated that proteolytic enzymes play important roles as mediators of glomerular injury. The aim of the study was to assess intraglomerular fibronectin and laminin contents as well as cysteine proteinases in activity chronically rejected human kidneys. We investigated kidney tissue from graftectomy specimens obtained from 11 patients with end-stage renal disease following chronic rejection. A group of 9 patients undergoing nephrectomy because of cancer served as a control group, but only not involved parts of the kidneys were used. When intraglomerular laminin contents were related to DNA content, significant accumulation in chronically rejected allografts was found in comparison to controls (382 +/- 171 micrograms per microgram DNA and 190 +/- 82 micrograms per microgram DNA, respectively, p < 0.01. The accumulation of fibronectin was higher than in controls, however the difference was not significant. When proteinase activity was related to intraglomerular DNA content, significantly enhanced cathepsin B and L activity was found in rejected kidney allografts (57 +/- 16 nmol AMC/min per mg DNA) in comparison to controls (15 +/- 2 nmol AMC/min per mg DNA). Summarizing, we observed accumulation of fibronectin and laminin in glomeruli and simultaneously an excess of proteolytic activity in human chronically rejected kidneys. The above phenomenon indicates that a very active metabolic process takes place in glomeruli during rejection.

Antioxidant defence of red blood cells and plasma in stored human blood

Blood collected routinely from donors, and preserved with CPDA-1 anticoagulant (citrate, phosphate, dextrose, adenine), was investigated. The concentration of reduced glutathione, and glutathione peroxidase, glutathione S-transferase, glutathione reductase, superoxide dismutase, and catalase activities in erythrocytes, as well as the total radical-trapping antioxidant parameter in plasma were determined on days 1, 3, 7, 12, 16, 20 and 25 of storage. At the end of the study, a 30% decrease in the reduced glutathione concentration (P < 0.001) and decreases in glutathione S-transferase (over 20%, P < 0.001), glutathione reductase (over 8%, P < 0.01) and superoxide dismutase (over 10%, P < 0.001) activities in erythrocytes, together with up to a 30% diminution of total antioxidant activity in plasma (P < 0.001) were noted. Thus, during blood storage, glutathione-dependent antioxidant systems in erythrocytes and antioxidant defence in plasma are depleted. From the present study, a twelve-day period can be considered a safe storage limit. The sequence of events occurring in stored blood, leading to peroxidative injury in erythrocytes, is discussed.

Antioxidant and glutathione-associated enzymes in Wilms' tumour after chemotherapy

The present study demonstrates the activities of antioxidant and glutathione-associated enzymes and the level of glutathione in Wilms' tumour (nephroblastoma) samples after chemotherapy (mainly actinomycin D and vincristine). We observed higher activity of superoxide dismutase in Wilms' tumour compared to adjacent morphologically unchanged kidney. On the other hand, in this tumour lower activities of catalase and the glutathione-associated enzymes glutathione synthetase, gamma-glutamyl transpeptidase, glutathione reductase and total glutathione S-transferases (GST) were found. Using isoelectric focusing we separated different forms of GST in tested tissues and revealed lower activities of the basic enzymes in Wilms' tumour, which may be responsible for the decrease of total GST activity. Moreover, we found the acidic isoenzymes to be the predominant class of GST in nephroblastoma. In Wilms' tumours with unfavourable histology a high activity of these isoenzymes together with a high level of GSH were observed. We suggest that these parameters may participate in the known phenomenon of anticancer drug resistance of tumours with unfavourable histology.

[The analysis of cadmium and lead levels in the umbilical blood and first urine in newborn infants]

Umbilical blood Cd and Pb concentration determined by AAS (PE Zeeman 3030) equaled 0.15 micrograms/dl and 4.09 micrograms/dl, respectively. The Cd level in the first urine equaled 0.02 micrograms/dl, that of Pb, 0.78 micrograms/dl.

[Prognostic factors in neuroblastoma in children]

The paper presents the review of prognostic factors which were investigated from the first interests of neuroblastoma, as a model for cancer biology in pediatric oncology. The authors on the basis of other authors experiences and on the own observations, as well stress the importance of basic sciences from the field of molecular biology, cytogenetics and biochemistry, leading to better understanding of the nature of neuroblastoma and to introduction of rational treatment. The stratification of neuroblastoma patients according to the known prognostic variables influenced favourably treatment results.

[Defense system antioxidants in blood of children with neoplasms. II. Antioxidant enzymes and lipid peroxidation in erythrocytes]

The aim of the work was to investigate selected parameters of antioxidant defence in red blood cells of children suffering from various types of solid tumors. In patients with these tumors, glutathione reductase and glutathione S-transferase activities were found to be reduced in comparison to healthy children.

[Blood antioxidant defense in children with malignant disease. I. Plasma antioxidant activity and level of ceruloplasmin and transferrin]

In this study we examined selected elements of the antioxidant defence system in the plasma of children with the most common solid tumors (nephroblastoma, neuroblastoma, rhabdomyosarcoma, osteosarcoma). We observed a significant increase of plasma antioxidant activity (AOA) in the majority of the examined children. This factor changed during clinical treatment, i.e. induction of chemotherapy, surgery and/or radiotherapy and during maintenance chemotherapy. We conclude that the elevated plasma antioxidant activity in children with malignancy may be due to the higher concentration of ceruloplasmin in affected children than in their healthy counterparts.

Lipid peroxidation in hypertrophic rat kidney

During compensatory growth of kidney, microsomal lipid peroxidation is unchanged in the hypertrophy phase and is doubled in a period of hyperplasia. The maximum lipid peroxidation is preceded by a 2-fold increase in the content of cytochrome P-450. Both in microsomes and cytosol, intense peroxidation of lipids is accompanied by a decrease in glutathione content.

Development of tyrosine aminotransferase and para-hydroxyphenylpyruvate dioxygenase activities in fetal and neonatal human liver

In livers of fetuses of 220--340 g body wt, total cytosolic tyrosine aminotransferase activity was 1.0 nmol of product/mg of protein per min, and the corresponding values for autopsy livers of newborns of 740--1,475 g and 2,600--3,650 g were 1.5 and 5.7, respectively, as compared with the adult value of 12.7. On the other hand, para-hydroxyphenylpyruvate dioxygenase activity is at adult level already in fetuses less than 340 g body wt. The Km value for tyrosine of tyrosine aminotransferase (1 mM) was considerably higher than the corresponding value for para-hydroxyphenylpyruvate of para-hydroxyphenylpyruvate dioxygenase (50 micro M). These results suggest that tyrosine aminotransferase is the rate limiting enzyme in the catabolism of tyrosine in premature infants.

The effect of unilateral nephrectomy and sham operation on tyrosine content and activity of tyrosine aminotransferase in the rat

During the first four days after unilateral nephrectomy the free tyrosine content in plasma, liver and hypertrophic kidney was decreased by more than 50% as compared with the values observed in intact rat. After sham operation, the content of tyrosine was decreased to the same extent. The activity of tyrosine aminotransferase in liver was doubled two days after sham operation: no such increase was observed after unilateral nephrectomy. At the same time a decline of the enzyme activity in kidney was demonstrated after both types of surgery. Hydrocortisone in a single i.p. dose stimulated enzyme activity in the liver of intact rats three-fold, and more than four-fold after nephrectomy and sham operation. In kidney of intact rat, as a result of hydrocortisone treatment, the enzyme activity was doubled; it was, however, insensitive to this treatment after unilateral nephrectomy, and increased only by 20% after sham operation. It is suggested that the changes in tyrosine content and tyrosine aminotransferase activity observed after unilateral nephrectomy were not due to stress alone, but underwent regulation aimed at assuring a sufficient level of this amino acid for metabolism.