Biomedical subjects

C Kovac

Publications and source records attributed to C Kovac.

24 records · Page 2Linked to original sources

PubMed1995

Microheterogeneity of acute phase proteins in patients with clinically active and clinically nonactive osteoarthritis.

Microheterogeneity of two acute phase glycoproteins, alpha-1-acid glycoprotein (AGP) and alpha-1-antichymotrypsin (ACT), concentrations of AGP, ACT, and C-reactive protein (CRP), and levels of three cytokines: interleukin 1 beta (IL-1-beta), interleukin 6 (IL-6), and tumor necrosis factor alpha (TNF-alpha) were determined in 61 serum samples and 7 synovial fluids (SFs) obtained from patients (n = 61) with osteoarthritis. Using affinity immunoelectrophoresis with concanavalin A (conA), a significant decrease in the reactivity of AGP and ACT with this lectin was found in patients with clinically active osteoarthritis when compared to those with clinically nonactive disease (p < 0.001 and p < 0.05, respectively). There was no increase in the concentration of AGP, ACT, and C-reactive protein (CRP) in the sera examined. In particular, no increase in the serum level of these proteins was found in the patients with clinically active disease. Low concentrations of IL-6 and TNF-alpha were found in most sera and SFs examined. In 6 out of 7 SFs available, IL-6 concentrations were higher than in the respective serum samples but for TNF-alpha the same could be shown in one case only. Low concentrations of IL-1-beta were found in 4 serum samples obtained from patients with clinically active osteoarthritis and in no SF specimen studied. In the entire group, serum level of TNF-alpha correlated weakly with the AGP and ACT reactivity coefficients with conA (r = 0.3634, p < 0.005 and r = 0.3324, p < 0.02, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1994

Cardiac involvement in Ribbing's disease.

Cardiac involvement was assessed in 14 patients with Ribbing's disease, a rare hereditary sclerosing bone dysplasia. When compared to age-, sex- and blood pressure-matched controls, the patients with Ribbing's disease had significant alterations in left ventricular systolic and diastolic function and an impaired exercise tolerance. Supraventricular and ventricular arrhythmias also tended to be more frequent in these patients than in controls. In conclusion, Ribbing's disease, initially described as a skeletal disease only, also involves the cardiovascular system. Despite its rarity, the expression of the disease is easily followed and identification of the genetic defect could shed some new light on the pathophysiological mechanisms linking hypertension, myocardial hypertrophy and diastolic dysfunction.

Adolescent↗

PubMed1990

Selective advantage of fra (X) heterozygotes.

The high incidence of the fra (X) syndrome (about 1:2000 male newborns) requires an explanation in view of the low fitness of mentally retarded hemizygous males and heterozygous females. In the past, it has been proposed that the mutation rate may be unusually high, and that mutations occur exclusively in male germ cells. According to an alternative hypothesis, a moderately high mutation rate might combine with a selective advantage of clinically unaffected heterozygotes. In earlier studies, such a combined hypothesis was shown to lead to plausible implications regarding mutation rate and fitness. Moreover, a mutation rate in male germ cells of the magnitude required by the exclusive mutation hypothesis was excluded by studies on comprehensive pedigree data. In this third study in the series, an increased fitness of heterozygous females is demonstrated directly by a comparison of the reproductive performance of heterozygotes with that of adequate controls (mothers and grandparents of Down's syndrome patients). Since, average numbers of children have decreased during recent decades in populations of industrialized countries, heterozygotes (mothers of affected probands and their female relatives in their own generation) were subdivided into those born before and after 1940. Moreover, sibship sizes of probands' mothers and fathers were analyzed separately for family branches in which the fra (X) trait segregated (mostly the maternal branch), or did not segregate (in most instances the paternal branch). In all four categories reproductive performance in heterozygotes was found to be higher than in the controls. This difference was significant statistically for two of the four groups; it was small and nonsignificant only for the parental family branch in which the fra (X) mutant did not segregate and for mothers born after 1940. Fitness estimates ranged between 1.11 and 1.36. A higher incidence of dizygotic twinning suggests a biological component for this increased fertility. On the other hand, fra (X) families have a significantly lower social status than the controls. This suggests a socio-psychological component of their higher fertility. Apparently, both components contribute to their fertility; at present, their relative importance cannot be assessed.

Birth Rate↗

PubMed1976

Activity and properties of CTP: cholinephosphate cytidylyltransferase in adult and fetal rat lung.

Cholinephosphate cytidylyltransferase (CTP : cholinephosphate cytidylyltransferase, EC 2.7.7.15) is located in both the microsomal and supernatant fractions of adult lung when the tissue is homogenized in 0.145 M NaCl. The activity is located predominantly in the supernatant fraction in fetal lung. Cholinephosphate cytidylyltransferase in the supernatant from fetal lung is stimulated 4- to 6-fold by the additions of total lung lipid. Serine phosphoglycerides and inositol phosphoglycerides specifically caused stimulation whereas choline phosphoglycerides and ethanolamine phosphoglycerides produced no stimulation. Lysophosphatidylcholine cause some stimulation, but only at high concentrations. A number of detergents were investigated. All produced inhibition except for the ampholytic detergent, miranol H2M which was not inhibitory. None of the detergents produced any stimulation of activity. Cytidylyltransferase activity in fetal lung when assayed in the absence of lipid is about 25% of the adult. The activity when assayed in the presence of lipid is equal or slightly higher than adult levels. The activity, measured without added phospholipid, increases 5- to 6-fold within 12 h after birth, to values higher than in the adult. The activity, measured in the presence of phospholipid, increased almost linearly from -2 day until +1 day. There is an inverse relationship between the concentration of phospholipid in the fetal lung supernatant and the degree of lipid stimulation. Chromatographic experiments with Biogel A 1.5 columns have shown that cytidylyltransferase can exist in two molecular sizes, a small molecular size that requires phospholipid for activity, and a larger molecular weight species which does not require the addition of phospholipid for activity. Fetal lung has a higher proportion of the low molecular weight form than adult lung. The small molecular weight species can be converted to the larger molecular weight form by the addition of phospholipids.

Aging↗

PubMedDate not supplied

[Determination of regional rate of glucose metabolism in lumbar muscles in patients with generalized tendomyopathy using dynamic 18F-FDG PET].

Generalized tendomyopathy (GTM), or fibromyalgia (FM), is a disease characterized by wide-spread pain in the musculoskeletal system which usually begins at a single site, e.g., as low-back pain or cervical syndrome, and develops into generalized pain over months or years. The disorder affects primarily women, beginning around the age of 35 and reaching its peak during or after the menopause. Its etiology is still unknown. Secondary forms are observed particularly in rheumatoid arthritis. In order to get more information on FM we determined the local metabolic rate of glucose in vivo in the skeletal muscle (lumbar region) with dynamic 18F-FDG positron emission tomography (PET). 2 healthy volunteers and 6 female patients with FM reaching in age from 31 to 53 years were scanned. As 18F-FDG PET scanning is a metabolic tool, it is crucial to observe standardized conditions of metabolic steady-state. We used, therefore, the hyperinsulinemic euglycemic insulin clamp technique to stimulate the myogenic glucose uptake under stable plasma-glucose levels. The local metabolic rates of glucose utilization were estimated with a non-linear least squares fit on the 3 compartment 18F-FDG-model. A lumped constant of 0.67 was assumed. Under glucose clamp conditions patients with FM showed a significantly (p < 0.001) lower metabolic rate of glucose (4.3 +/- 1.1) mumol/100 g tissue/min compared with normal volunteers (8.5 +/- 2.3 mumol/100 g/min). Due to a significantly (p < 0.005) increased glucose backflow from tissue into the vascular space (k2 in the kinetic model) the rate of phosphorylation was markedly reduced in patients with FM.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMedDate not supplied

[Methods for detection of changes in muscle tonus].

Muscular spasm is a frequent symptom which is difficult to record precisely. On the basis of literature on the subject and of own studies, we undertook to describe various methods of examination which could be used to demonstrate such changes. Up to now, palpation is still the most important and most exact method for the experienced examiner. In this way local as well as extended muscular spasms can be made evident. The disadvantage however is the lack of objective proof. The easy-to-use Tissue-Compliance-Meter of Fischer, which measures the consistency of soft tissue, documents the intraindividual difference rather than the interindividual difference. This is due to the individually variable thickness of the subcutaneous fatty tissue. However, on the whole there is a good correlation to the findings of palpation. The pendulous-test and badismography allow especially the conclusion with regard to unilateral changes of tonus in the gluteal and upper leg muscles. This method also very well suits the intraindividual comparison, but less so the interindividual one. The continuous electromyogram is able to show the enhanced activity in spasmotic muscles also during sleep. The evaluation of enhanced muscle activity remains uncertain when using plain electromyogram. Recording of muscle tissue oxygen pressure is of little use to evaluate muscle spasm. Nonetheless, it provides interesting insights into pathogenetic questions. Thermography, measuring the blood circulation at the skin surface, is especially suited for perceiving intraindividual differences in case of muscle spasm. Nuclear magnetic resonance spectroscopy allows for noninvasive pH measurements in the muscle and therewith renders certain data concerning the degree of tension of this tissue. It is not yet suited for routine examination. The value of positron emission tomography for registering muscle spasm remains uncertain. Hopefully, this method, which documents the muscle energy metabolism, will enable us to more clearly evaluate muscle spasm than previous methods have done. Light and electron microscopic studies have provided contradictory results concerning histological changes in muscle biopsy in case of muscle spasm.

Adenosine Diphosphate↗