[Kinetic parameters of calcium binding to tissue structures in human acute hypercalcaemia].

Calcium binding kinetic by tissue structures was analysed in 19 health volunteers (13 men and 6 women) of the age group of 33 +/- 6.5 under conditions of acute hypercalcaemia followed by a drip i.v. infusion of calcium gluconate over 2.5 hours. At the end of each 30-minute period the calcium amount retained by tissue structures was recorded and the kinetic parameters of calcium binding were determined according to Langmuir and Scatchard. In all volunteers there was a segment of binding isotherm with positive cooperativity (direct regression in Scatchard) with analogous buffer capacity (beta) for calcium in Langmuir (0.58 +/- 0.24 L kg). One half of volunteers demonstrated cooperativity at [Ca++] 1.3-1.5, while another--at [Ca++] 1.0-1.3 mmol/L which corresponded to the differences in the association constant (Ka) and the number of interactive sites (n) with [Ca++] 1 mmol/L. Additionally, two segments of binding isotherm were detected with the successive binding of calcium to one set of noninteractive sites with similar kinetic parameters of calcium binding (beta, K(a), n). Four different curves of calcium binding in healthy volunteers were established. This study may serve as the basis for a functional diagnostic test of disorders of the tissue calcium-binding properties in different pathological conditions.

[The dynamics of biochemical markers of remodelling of bone tissue after liver transplantation].

The sample of 45 recipients (30 females and 15 males) after orthotopic transplantation of liver was examined thrice in dynamics. Three groups were formed according the resulted values of T-criterion of bone mineral density in the area of lumbar vertebrae. The bone mineral density of group A was considered as osteoporosis, of group B as osteopenia and of group C as physiologic norm. In early period (1-4 months) after orthotopic transplantation of liver gross disorders of bone metabolism were established in all recipients independently of the degree of bone mass loss. In distant period (up to 32 months) after orthotopic transplantation of liver the bone losses decreased entailing full normalization of bone metabolism in 37% of recipients with osteoporosis, 82% with osteopenia and 91% with normal bone mineral density.

[Level of aminoterminal type 1 procollagen propeptide--the bone formation marker--in the sera of healthy males].

The biochemical bone formation marker aminoterminal type 1 procollagen propeptide (total P1NP) was determined in 91 serum samples from healthy male donors aged 19 to 60 years, by using an "Elecsys Total P1NP" kit of reagents ("Roche-Diagnostics", Germany) on an "Elecsys 2010" electric chemiluminescence analyzer ("Roche-Hitachi", Japan). A relationship was found between the serum concentration of total P1NP and the age of the examined males. At the age of 19-20 years, the content of the propeptide is highest, at the age of 21-24 years, it decreased by 1.5-2 times, by the age of 30 years, there is its moderate decrease, which is then followed by its stabilization. The detected age-related changes reflect accelerated bone metabolism in young males during formation of the bone mass peak. The findings may be used as references in measuring male total P1NP on Elecsys automatic analyzers.

[Biochemical markers of bone formation in hemodialysis and after allotransplantation of cadaveric kidney].

AIM: To ascertain informative value of estimation of bone forming markers in patients on chronic hemodyalisis (CHD) and recipients of cadaveric kidney (CK). MATERIAL AND METHODS: Parathyroid hormone (PTH), beta-crosslaps (CTX), osteocalcin (OC), amino-terminal procollagen propeptide 1 (PINP), bone alkaline phosphatase (BAP), bone mineral density (BMD) were determined in 152 patients on CHD (89 males and 63 females aged 49 +/- 13 years) and 195 CK recipients (106 males and 89 females aged 42 +/- 12 years) 30 +/- 38 months after kidney transplantation. RESULTS: PTH, CTX and BAP determination specifies skeletal disease (secondary hyperparathyroidism or adynamic bone disease) in CHD patients. In patients with CK recipients osteoporosis differed from osteopenia by higher levels of PTH, CTX, OC in the absence of any differences in BAP, PINP. All bone forming markers were lower than CTX showing suppression of bone forming. Bone fractures in CK recipients' anamnesis were associated with OC and BAP decrease in men and low border of normal OC in women. Determination of bone formation and resorption markers in patients on CHD and CK recipients is of great clinical importance.

[The peculiarities of bone exchange disorder and its regulation in men after long terms following orthotopic heart transplantation and cadaveric kidney transplantation].

The study found bone exchange disorder manifested by accelerated bone resorption, retarded bone formation, and the loss of the bone mineral density (BMD) of the axial and peripheral skeleton in 19 men (39 observations) 66 +/- 44 months following orthotopic heart transplantation (OTHT) and in 92 men 45 +/- 28 months after cadaveric kidney transplantation. An accelerated bone resorption, more pronounced in cadaveric kidney (CK) recipients, is associated with hyperparathyroidism (HPT) and renal dysfunction, while bone formation retardation is associated with a decrease in insulin-like growth factor-1 level. An increase in osteoprotegerin level is of compensatory character. The prominence of HPT depends on the degree of renal dysfunction; in CK recipients it also depends on the degree of the reduction in the levels of biologically active testosterone and estradiol. Reduction in BMD of the peripheral skeleton after OTHT are associated with the degree of renal dysfunction and a decrease in free testosterone index; after CK transplantation it is associated with HPT, the cumulative dose of glucocorticoids, reduction in the levels of biologically active testosterone and estradiol, as well as sex-hormone binding globulin (SHBG); reduction in spine BMD is only associated with SHBG.

[Biochemical markers of bone metabolism and bone tissue losses after allotransplantation of the cadaveric kidney: a cross-sectional].

The biochemical markers of bone metabolism (osteocalcin (OC), C- and N-terminal procollagen I propeptides (PICP) and PINP), bone alkaline phosphatase (BALP), deoxypyridinoline (DPD), beta-crosslaps (beta-CL), bone acid phosphatase (BAP), osteoprotegerin (OPG), insulin-like growth factor I (IGF-I), and parathyroid hormone (PTH)), daily urinary calcium excretion (DUCE) (intestinal calcium absorption), and lumbar and hip bone mineral density (BMD) were determined in 195 patients (78 females and 74 males with normal function of the grafted kidney and 11 females and 31 males with chronic renal failure (CRF) 40 +/- 33 months after renal transplantation (RT). All RT recipients received triple immunosuppressive therapy (cyclosporin, prednisolone, and azathioprine). All groups showed a significant increase in resorption markers and a moderate increase in bone formation markers (except BALP), which suggested bone remodeling dissociation, as well as elevated levels of PTH and OPG and decreased DUCE and BMD in the vertebral column and hip. Increased bone metabolism and decreased intestinal calcium absorption were largely pronounced in CRF. In the majority of recipients, the BMD reduction in the vertebral column and hip was moderate (osteopenia) and only in male recipients with CRF, axial osteopenia was concurrent with peripheral osteoporosis. The main predictor of accelerated bone metabolism and BMD losses following RT was hyperparathyroidism mainly caused by decreased renal graft function. Decreased IGF-I may be a cause of bone remodeling dissociation after RT/ and the increase in OPG seems to be compensatory, which suppresses bone resorption and reduces bone losses.

[The functional characteristics of the calcium-regulating systems and the calcium content of the blood following a cadaveric kidney allograft]. / Osobennosti funktsional'nogo sostoianiia kal'tsiireguliruiushchikh sistem i soderzhanie kal'tsiia v krovi posle allotransplantatsii trupnoi pochki.

Total plasma calcium (Ca), Ca renal reabsorption, Ca tissue transport, parathyroid hormones and calcitonin were measured in fasting 30 recipients of a renal allotransplant, 95 healthy subjects, 9 primary hyperparathyroidism patients, 12 patients with bronchial asthma and exogenic hypercorticism. Total Ca proved normal in 26 but lowered in 4 recipients. Canalicular Ca reabsorption got enhanced in 17 recipients with high parathormone levels in 10 of them. Normal Ca reabsorption was registered in 13 recipients through parathormone elevated in 6 of them. Tissue Ca binding enhanced in its high reabsorption in the transplant. The binding did not depend either on parathormone secretion intensity or cyclosporin A treatment, being partially determined by steroid therapy. When investigated under Ca intravenous drop infusion in 20 recipients and 14 healthy subjects, Ca tissue binding confirmed its physiochemical nature and revealed in one third of the recipients impaired buffer capacity of the tissues as well as Ca retention and release rates. The impairment was related neither to changes in the basal level nor with secretion fluctuations of parathormone and calcitonin. Increased tissue Ca binding accounts for the absence of hypercalcemia in renal transplantation.

[Calcium-binding properties of tissue proteins after kidney allotransplantation]. / Kal'tsiisviazyvaiushchie svoistva tkanevykh belkov posle allotransplantatsii pochki.

The kinetics of calcium binding to tissue substrates in hypercalcaemia, induced by intravenous constant rate infusion of calcium gluconate were studied in 19 patients after renal transplantation and in 14 healthy volunteers. Langmuir, Scatchard and Hill analysis revealed the positive cooperative mechanism of calcium binding to tissue in all patients and in healthy volunteers. These results provide indirect evidence of binding of calcium to tissue proteins. The significant decrease of the values of specific buffer capacity of tissue proteins, pool of exchangeable calcium and also the effective Ka were observed in 37% of patients. These changes are proposed to play a role in the pathological calcification of vessels and soft tissues in patients after renal transplantation.

[Correlations of cardiorespiratory and metabolic reactions in humans with graded physical load]. / Vzaimosviaz' kardiorespiratornykh i metabolicheskikh reaktsii cheloveka pri stupenchato vozrastaiushohei fizicheskoi nagruzke.

Bicycle ergometry tests of graded workloads were performed by 9 healthy men, aged 25 to 40 years. During the tests cardiorespiratory parameters, lactate and pyruvate concentrations, as well as lactate dehydrogenase (LDH) and NADP-dependent isocitrate dehydrogenase (ICDH) activities were measured. It was shown that the threshold of anaerobic metabolism can be measured not only by traditional methods (with respect to variations in pulmonary ventilation and venous blood lactate) but also in terms of ICDH increase as a function of the workload. Mathematical processing of the resulting data did not reveal a correlation between the total oxygen debt and lactate in blood. In contrast, a close correlation between the debt and LDH activity at the end of the test was found. These observations have demonstrated that biochemical measurements should find a wider application in evaluations of energy costs of various workloads.

[Tolerance of functional and exercise tests during 1-year antiorthostatic hypokinesia]. / Perenosimos't obsleduemymi funktsiona'lno-nagruzochnykh prob v usloviiakh godovoi antiortostaticheskoi gipokinezii.

During 370 days 9 healthy young volunteers were exposed to antiorthostatic hypokinesia. Group A consisting of 4 subjects performed exercises similar to those regularly made by Mir crewmembers and Group B consisting of 5 subjects did not exercise for 120 days and then performed experimental exercise regimens. It was demonstrated that the health status of men long exposed to head-down tilting can be controlled with the aid of various countermeasures. As a result of the exposure, orthostatic and exercise tolerance diminished. In view of the fact that the changes observed were more pronounced in the Group B subjects, it can be concluded that the countermeasures used were more effective in Group A subjects.

[Effect of a 30-day period of hypokinesia on various physiologic and biochemical indicators during maximal physical load]. / Vliianie 30-sutochnoi gipokinezii na nekotorye fiziologicheskie i biokhimicheskie pokazateli pri maksimal'noi fizicheskoi nagruzke.

Exercise tolerance of test subjects who remained bed rested (Group A) and who exercised while being supine (Group B) was measured before and after 30-day head-down tilt (-8 degrees). Special attention was given to the parameters that characterize energy supply of working muscles. The data obtained after 30-day bed rest did not reveal any changes in the Group B subjects and showed the following changes in the Group A subjects: maximum oxygen consumption decreased by 10.1% (p less than 0.05), the time within which the anaerobic metabolism threshold was attained decreased by 17.2% (p less than 0.05), and lactate concentration at the workload end decreased by 24.7%, while the pyruvate concentration and the lactate/pyruvate ratio remained unchanged. The results indicate that prolonged aerobic workload after 30-day bed rest seems to be limited by functional changes in oxygen transport rather than by the factors associated with changes in energy supply of working muscles.

[Functional status of the human cardiorespiratory system after 30 hours' antiorthostatic hypokinesia]. / Funktsional'noe sostoianie kardiorespiratornoi sistemy cheloveka posle 30-sutochnoi antiortostaticheskoi gipokinezii.

Before and after 30-day head-down tilt (-8 degrees) the cardiorespiratory function of six healthy volunteers was assessed using an exercise test (aerobic workload on the treadmill that grew to the maximal level). After hypokinesia the maximal oxygen consumption decreased by 9.9% and total oxygen debt by 23% (P less than 0.05). The bioelectric activity of the heart showed a decrease of the TA wave by 34% and the TD wave by 30% (P less than 0.05). These changes give evidence that the functional capacity of the cardiorespiratory system declined and as a consequence the ability of the test subjects to perform sustained physical work of aerobic character also decreased.