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Biomedical subjects

J M Mbuyi-Muamba

Publications and source records attributed to J M Mbuyi-Muamba.

At least 19 recordsLinked to original sources
PubMed1998

Low frequency of HLA-B27 and scarcity of ankylosing spondylitis in a Zairean Bantu population.

Ankylosing spondylitis (AS) is an inflammatory rheumatic disease which is thought to be rarely seen in African Blacks. Its genetic predisposition has been stressed in Caucasians where the HLA-B27 antigen is firmly linked to the disease. In the present study, HLA-B27 antigen was determined in 146 individuals of Bantu root. Only one of these subjects was found to possess HLA-B27 antigen. This study correlates the low frequency of HLA-B27 with the observed scarcity of AS in patients attending a clinic in Kinshasa for osteoarticular diseases.

Adult↗
PubMed1998

HLA-DR gene frequencies in a Zaïrean population with particular reference to rheumatic diseases.

Epidemiological studies have shown that rheumatic diseases such as rheumatoid arthritis and systemic lupus erythematosus are uncommon in black Africans, and in this population the prevalence and the clinical features of these rheumatic diseases are variable. Environmental and genetic factors have been pointed out to explain this variability. In the present study, HLA-DR genes have been determined in a Zaïrean population in order to compare our results with those found elsewhere in other black populations of the same Bantu origin. Our results show that the frequency of HLA-DR1 is higher than in Nigerians, Zimbabweans and Xhosas, the decrease in Xhosas being statistically significant (p < 0.006). The HLA-DR3 frequency is higher in Zaïreans than in Nigerians but not significantly, while it is lower than in Xhosas (p < 0.003) and in Zimbabweans (not significant). The HLA-DR4 frequency is higher in Zaïreans than in Nigerians but it is lower than in Xhosas and Zimbabweans; the differences are not statistically significant. The HLA-DR8 frequency is lower in Zaïreans than in Nigerians while it is higher than in Xhosas (p < 0.002) and in Zimbabweans (not significant). These data suggest that genetic factors partly explain the clinical and epidemiological variability of rheumatic diseases in black Africans.

Adult↗
PubMed1997

Role of alfacalcidiol on bone quality and immunomodulation in autoimmune disease and organ transplantation.

In autoimmune diseases, as well as in organ transplantation, corticosteroids are often an obligatory part of the treatment regimen. The deleterious effect of corticosteroids on bone metabolism is well known, although still controversial [1-3]. It is easier to maintain bone mass than to restore it. Although the treatment of choice for prevention of bone loss is hormone replacement therapy, it cannot always be applied, and for many reasons compliance is low over the world. Alternative strategies to prevent bone loss are now tried out in many centers. Calcitonin and bisphosphonates are well-known antiresorbing drugs, but costs and long-term efficiency for calcitonin and fear for bone toxicity for the bisphosphonates limits their use for prevention. An attractive strategy to prevent osteoporosis is the treatment with alfacalcidiol because it is a natural product with important effects on bone metabolism in physiological and pharmacological dosages. Calcium absorption from the gut and mineralization of the bone matrix are optimalized by alfacalcidiol. The purpose of this paper is to report on our experience with alfacalcidiol concerning bone mass and quality in corticosteroid-induced osteoporosis in experimental animals and on long-term bone quality in autoimmune diseases and organ transplantation. We have studied the effects of alfacalcidiol on bone mass and quality in ovariectomized animals with and without corticosteroids. In these fundamental studies we have found that alfacalcidiol had a profound protective and curative effect not only on bone mass but also on bone quality as tested by mechanical testing, namely, impact torsional loading test of whole bones. The combination of alfacalcidiol with estrogens was less effective than alfacalcidiol, but more effective than estrogens alone [4-6] (Fig. 1).

Autoimmune Diseases↗
PubMed1996

Hydroxyprolinuria in normal Zairean children.

Hydroxyprolinuria has been measured in 378 normal Zairean children aged between 3 and 13 years using the Kivirikko's method; 192 of them were boys and 186 were girls. Results show an age-related increase of urinary excretion of hydroxyproline in both sexes, girls having higher absolute values than boys. However, this difference is pronounced when values are corrected according to body size. Our values are slightly higher than those found in the literature.

Adolescent↗
PubMed1994

Bone tissue composition: biochemical anatomy of bone.

Bone is chemically built up as a mineralized matrix which comprises collagen and a small amount of noncollagenous proteins. This paper points out some useful methods to evaluate the bone composition. Demineralizing extraction of bone powder with EDTA allows the determination of matrix size and degree of extractability. These parameters vary with bone type, anatomical site of the bone, disease, species, and drug treatment. The study of bone particles in situ can be done by separation of bone powder according to their density. A shift of the bone particles to higher density fractions reflects an increased amount of older, more mineralized osteons in the bone with its consequences on the mechanical competence of the bone. Quantity and quality of bone matrix mineralization are related to bone cell activity which can be studied indirectly by further exploration of the composition of the bone matrix. Many noncollagenous proteins are buried in the extracellular bone matrix from where they can be released when bone is resorbed. These proteins can then act on bone cells in an autocrine or paracrine manner. Altered concentrations of noncollagenous proteins in bone matrix are described in three pathological conditions associated with changes in other bone properties: osteoarthritis, osteopenia, and osteogenesis imperfecta. The functional significance and origin of these changes will have to be subjected to further study.

Animals↗
PubMed1993

Ankylosing spondylitis in two Zaïrian brothers.

Ankylosing spondylitis has never been described in Zaïre and is considered to be rare in black African populations. We report two cases observed in the University Hospital of Kinshasa. The two patients are brothers. The diagnosis is based on anaemnestic, clinical and radiological findings. We therefore demonstrate the existence of this disease in Zaïre and presume that other similar cases may be diagnosed.

Arthrography↗
PubMed1993

Drug trials in developing countries: the need for ethics.

Drug trials in developing countries may contribute to a better understanding of the properties of antirheumatic drugs. Before this can be done, however, there is a need for ethical committees to oversee the trials and for effective regulation of drug availability.

Anti-Inflammatory Agents↗
PubMed1989

Collagen and non-collagenous proteins in different mineralization stages of human femur.

Mineralized tissues exhibit varying degrees of mineralization in different areas within the same bone. Using the technique of density gradient fractionation, bone powder from the diaphysis of human femur has been separated in different fractions corresponding to the degree of mineralization. Isolated bone fractions were analysed for their content in collagen and non-collagenous proteins. The results showed marked differences between compact and spongy bones, this latter containing higher proportions of little mineralized bone particles than the former (p less than 0.01). The ethylenediaminetetra-acetic acid (EDTA) extractability and the bone matrix size decreased relative to the decrease in specific gravity of bone particles. Among the matrix components of different fractions, sialoprotein consistently increased with the increase in specific gravity while proteoglycan decreased in reverse manner to the increase in collagen. However, in the most mineralized fraction (specific gravity: 2.33 g/cm3), the proteoglycan amount increased while collagen decreased. In conclusion, this study of bone maturation in human femur confirms the suitability of the technique of density gradient fractionation in the studies of bone matrix-mineral interactions. Apart from the fraction with the highest specific gravity, the analytical results obtained in fractions are similar to those observed in age-related bone changes, suggesting that the increase in mineralization degree of bone particles may be related to their age.

Aging↗
PubMed1987

Studies on EDTA extracts and collagenase digests from osteoporotic cancellous bone of the femoral head.

Using EDTA extraction and collagenase digestion, cancellous bone of the femoral heads from 10 normal and 9 osteoporotic subjects were analyzed for their contents of collagen, sialoprotein, proteoglycan and carbohydrate. The percentage of extracted matrix proteins of the osteoporotic bone in EDTA was significantly decreased, as was the collagenase-resistant fraction (p less than 0.05). The sialic acid level in osteoporotic bone matrix was lower than in controls (p less than 0.05). The alterations found in bone matrix constituents in osteoporotic bone relative to controls suggest that in osteoporosis and fractures, not only bone mass changes, but also bone quality changes play a role in bone strength.

Aged↗
PubMed1987

Biochemical anatomy of human bone: comparative study of compact and spongy bone in femur, rib and iliac crest.

Using EDTA extraction procedure, compact and spongy bone from human femur, rib and iliac crest were compared in terms of their content in collagen, sialoprotein, proteoglycan and carbohydrate. The bone matrix sizes displayed significant variations, the femur having the smallest size and iliac crest the largest one. No significant difference in the matrix size has been found between the spongy and compact bone. The EDTA extractability of the spongy bone was higher than that of the compact bone, with femur showing the lowest extractability. The collagen content of the 3 bones studied was similar although the femur had slightly lower values. The sialic and uronic acids and hexose contents were higher in the femur than in the rib and iliac crest. The collagen/hexose, collagen/sialic acid and collagen/uronic acid ratios in the bone matrix were highest in the iliac crest and lowest in the femur, suggesting that alterations in the amounts of bone matrix can affect the mechanical properties of different parts of the bony skeleton and vice versa.

Bone and Bones↗
PubMed1986

Bone mass measured by photonabsorptiometry and radiogrammetry in Wistar rats. Age and sex variations.

Using radiogrammetric and photonabsorptiometric methods, we determined changes in bone mass in Wistar rats as a function of age and sex. In the four age groups studied (10-, 18-, 30-, and 78-week-old rats), males displayed greater bone mass than females. With increasing age, bone mass also increases up to the 78th week. However, the rate of this increase was slower in the 78-week age group. Whereas the length and periosteal diameter of the bones studied were increased in old age groups, the endosteal diameter decreased in females and increased in males. The results show that, unlike human bone, rat bone mass persistently increases with aging, and female rats continue to gain bone at the endosteal site. Furthermore, these findings demonstrate that radiogrammetric morphometry and photonabsorptiometry may be used as an experimental tool to investigate bone mass changes in small animals.

Absorptiometry, Photon↗
PubMed1984

Chemical composition of normal and osteoarthrotic cancellous bone of the femoral head. Studies of EDTA extracts and collagenase digests.

Using EDTA extraction and collagenase digestion, cancellous bone from the femoral heads of ten normal and eight osteoarthrotic individuals was analyzed for its content of collagen, sialoprotein, proteoglycan, and carbohydrate. The EDTA extractability of the matrix proteins of the osteoarthrotic bone was significantly increased (P less than 0.001), as was the soluble collagenase-resistant fraction (SCRF). EDTA residues, bone matrix size, the collagenase-resistant fraction (CRF), and the insoluble collagenase-resistant fraction (ICRF) of the osteoarthrotic cases were not different from those of the controls. The amounts of carbohydrate and proteoglycans were considerably elevated in the bone matrix of the osteoarthrotic bone (P less than 0.01 and P less than 0.001, respectively). In the EDTA extracts, sialoprotein and proteoglycan contents were found in significant higher amounts (P less than 0.05 and P less than 0.01, respectively) in the osteoarthrotic cases. In the SCRF, the hexose and sialic acid contents were higher in the osteoarthrotic bone (P less than 0.01), while in the ICRF all the analyses were significantly increased in the osteoarthrotic bone (P less than 0.001). The ratios of collagen to non-collagenous components were lower in the osteoarthrotic than in normal bones. The quantitative and qualitative variations in cancellous bone proteins from the femoral head in osteoarthrosis found in this study suggest that alterations in subchondral bone play a role in the pathophysiology of cartilage degeneration in osteoarthrosis.

Aged↗
PubMed1984

Effects of pregnancy on bone matrix proteins in Wistar rats.

Using an EDTA extraction procedure, bones from pregnant Wistar rats were analyzed for their content of collagen and non-collagenous components (sialoprotein, proteoglycan and carbohydrate). The bone matrix size was found to be smaller in pregnant rats than in normal rats (19.5% vs 17.5% of the dry weight bone). The EDTA extractability of the bone protein from pregnant rats was higher than that from controls (2.6% vs 1.9% dry weight bone). EDTA extracts from pregnant rats contained higher amounts of soluble collagen (1.6% vs 0.5% of dry weight tissue) and lower amounts of non-collagenous components (1.65% vs 2.23% for hexoses, 2.38% vs 3.95% for sialic acid and 1.24% vs 1.73% for uronic acid). In bone matrix, collagen content was lower in the pregnant rats (9.45% vs 10.6%). Similarly, the amounts of non-collagenous components were slightly decreased in the bone matrix from the pregnant rats. The respective values were: 0.91% vs 0.93% for hexoses, 0.45% vs 0.52% for sialic acid and 0.39% vs 0.50% for uronic acid. These results suggest that in pregnancy collagen and non-collagenous protein content in bone is decreased while the total mineral content is increased.

Animals↗
PubMed1983

A comparative trial of timegadine and D-penicillamine in rheumatoid arthritis.

Forty-four patients with definite or classical rheumatoid arthritis were entered in a 48-week open study, comparing the long-term effects of Timegadine and D-penicillamine. Twenty-three and 21 patients were respectively allocated to the Timegadine and D-penicillamine groups. Two patients of the former group were lost for follow-up, soon after the first baseline. Thus data were available only for 42 patients, 21 in each group of whom eleven completed the 48-week period in each group. Seven patients in the Timegadine group stopped because of ineffectiveness, 2 because of skin eruption and 1 because of acute interstitial pneumonitis. In the D-penicillamine group, 9 patients dropped out: 3 because of proteinuria, 2 because of stomatitis, 1 because of dizziness and 1 because of headache. Pain (visual analogue scale), number of swollen and painful joints improved significantly in both groups (p less than 0.05). The acute phase reactants alpha1-acid-glycoprotein and ESR and the thrombocyte count significantly decreased in the penicillamine group (p less than 0.05). The other clinical, hematological and immunological tests did not change; neither did the liver and kidney function tests. The clinical results suggest that Timegadine is as effective as D-penicillamine in the treatment of rheumatoid arthritis. D-penicillamine takes advantage over Timegadine by decreasing significantly the acute phase reactants. However, Timegadine has a low profile of side-effects.

Adult↗
PubMed1983

Piroxicam versus naproxen in rheumatoid arthritis.

Forty-five patients with definite or classical rheumatoid arthritis were randomly allocated into two groups and treated with piroxicam 20 mg once daily or naproxen 250 mg twice daily in a 3-month, double-blind study. The results were available in 38 patients (21 in the piroxicam group and 17 in the naproxen group). Both drugs showed significant effects on the majority of clinical parameters compared to baseline. However, piroxicam was significantly superior to naproxen in reducing the grade of swollen joints. Moreover, piroxicam had better efficacy as shown by the number of patients who preferred it to previous therapy; 13 (62% of the patients entered) compared to 8 patients (47%) who preferred naproxen. Tolerance of the two drugs was similar. Two patients in each group dropped out due to side-effects.

Adult↗