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Biomedical subjects

R E Brenner

Publications and source records attributed to R E Brenner.

36 records · Page 2Linked to original sources
PubMed1993

Proliferation and collagen biosynthesis of osteoblasts and chondrocytes in short rib syndrome type beemer.

We report on a case of lethal short-limbed skeletal dysplasia with extremely short ribs, median cleft upper lip and palate, malrotation of intestine, lung hypoplasia with bilateral segmentation defect, atrial septum defect, union of distal urethra and vagina, and complex brain malformations. Based on radiological criteria and the pattern of associated abnormalities a short rib syndrome without polydactyly (Type Beemer) was diagnosed. Morphologically, the growth plate showed a reduced proliferation zone and an enlarged zone of hypertrophic cartilage. In addition, islands of persistent hypertrophic cartilage were present even in the metaphysis. In monolayer cell cultures supplemented with 10% fetal calf serum proliferation was normal in articular chondrocytes, reduced in costal chondrocytes, and elevated in osteoblasts from the patient. Clonal growth of costal and articular chondrocytes in methylcellulose could be stimulated normally by insulin-like growth factor-I (IGF-I), IGF-II, and human growth hormone (hGH). However, the response to transforming growth factor beta 1 (TGF-beta 1) was markedly elevated in articular chondrocytes of the patient compared to those of 3 fetal controls. Quantitative collagen synthesis in both osteoblasts and chondrocytes from the patient did not differ significantly from that of controls. Osteoblasts synthesized predominantly collagen I and minor amounts of collagen III, chondrocytes synthesized primarily collagen II. All collagen chains including CNBr-peptides of collagen II showed normal migration in PAA gel electrophoresis.

Cartilage↗
PubMed1993

Immunohistochemical localization of interstitial collagens in bone tissue from patients with various forms of osteogenesis imperfecta.

Immunohistochemical studies of bone from individuals with osteogenesis imperfecta (OI) type II, OI type III, or OI type IV demonstrate a similar pattern, but varying extent, of the abnormal presence of interstitial collagens in bone matrix. OI type II bone had nests of cartilage with type II collagen, and significant type III collagen in the bone matrix. In OI types III and IV, type II collagen was present only in epiphyseal cartilage but bone still contained type III collagen. These findings resembled those in developing fetal bone indicating the "immature" nature of OI bone.

Adult↗
PubMed1993

In vitro expression of osteoblastic markers in cells isolated from normal fetal and postnatal human bone and from bone of patients with osteogenesis imperfecta.

We studied the expression of osteoblastic markers in cultured cells isolated from the bone of 15 patients with different clinical forms of osteogenesis imperfecta (OI) and of seven fetal and postnatal controls. Cultured bone cells of ten OI patients produced abnormal collagen type I. Similar to controls, OI bone cells produced predominantly collagen type I with traces of collagen types III and V. The 1,25(OH)2 vitamin D3-stimulated synthesis of osteocalcin, a specific osteoblastic marker protein, was similar in OI bone cells and age-matched controls. Bone cells from fetal controls and from patients with the perinatal lethal OI type II produced less osteocalcin than bone cells from postnatal controls and surviving OI patients. OI bone cells responded to parathyroid hormone (PTH) by increased production of cAMP similar to controls. Bone cells from fetal controls and from OI type II donors showed a decreased response to PTH. Activity of the bone-liver-kidney isoenzyme alkaline phosphatase (AP) was detected in all control and OI bone cells. The expression of all osteoblastic markers was similar in bone cells producing abnormal collagen type I. These observations show that OI bone cells in vitro express a pattern of osteoblastic markers similar to age-matched control bone cells indicating that osteoblastic differentiation is not altered by the underlying defects of collagen type I metabolism in OI bone cells.

Alkaline Phosphatase↗
PubMed1993

The proton NMR spectrum in acute EAE: the significance of the change in the Cho:Cr ratio.

We have studied by nuclear magnetic resonance spectroscopy the evolution of the proton spectral changes in acute experimental allergic encephalomyelitis. We found an in vivo elevation in the ratio between the peaks assigned to "choline containing compounds" (Cho) and creatine plus phosphocreatine (Cr). This was associated with an increase in choline, betaine, and phosphorylcholine (PC) as well as a reduction in N-acetylaspartate (NAA), aspartate, N-acetylaspartatylglutamate and inositol in vitro. Histological examination revealed inflammation with no evidence of demyelination or neuronal loss. We conclude that the increase in the ratio of Cho:Cr was due to an increase in the concentrations of PC, betaine, and choline in association with inflammation, and not as others have suggested, with demyelination. The reported reduction in NAA may be due to dysfunction of neurones rather than their loss.

Animals↗
PubMed1993

Defective collagen fibril formation and mineralization in osteogenesis imperfecta with congenital joint contractures (Bruck syndrome).

We describe a male patient with osteogenesis imperfecta (OI) who was born with contractures of the knee, elbow and ankle joints. During the first 4 years he suffered from recurrent fractures. He has white sclerae, mild dentinogenesis imperfecta, multiple wormian bones, severe scoliosis and short stature. Morphological analysis of cortical bone revealed typical characteristics of OI including varying width of the osteoid, swollen mitochondria and a dilated endoplasmic reticulum of the osteoblasts. Collagen fibrils of the osteoid had a varying diameter, a feature not found in typical OI patients. Analysis of compact bone showed that the size of apatite crystals and the extractability of collagen with pepsin were markedly elevated compared to controls and other OI type III and IV patients. Lysyl hydroxylation of collagen from the organic bone matrix and the electrophoretic mobility of collagen alpha 1(I)- and alpha 2(I)-chains were normal. Our results provide evidence that this patient belongs to a subtype of OI. The biochemical studies indicate that the underlying defect involves defective fibril-formation of collagen type I leading to an altered mineralization of bone.

Abnormalities, Multiple↗
PubMed1993

Serum concentrations of procollagen I C-terminal propeptide, osteocalcin and insulin-like growth factor-I in patients with non-lethal osteogenesis imperfecta.

Serum concentrations of procollagen I C-terminal propeptide (PICP) were studied in 74 patients with various forms of non-lethal osteogenesis imperfecta and 27 unaffected family members. Using the standard deviation (SD) score, PICP concentrations were found to be > or = -1 SD in 16%, between -1 and -2 SD in 26% and < or = -2 SD in 58% of the patients with osteogenesis imperfecta compared to healthy controls. PICP values were lowest in osteogenesis imperfecta type I (-2.4 +/- 0.4 SD, n = 37) followed by type III (-1.9 +/- 0.5 SD, n = 13) and type IV (-1.3 +/- 0.7 SD, n = 20). Four patients with osteogenesis imperfecta with an atypical clinical course had normal or even elevated levels which may indicate heterogeneity in the underlying primary defects. In osteogenesis imperfecta type I, PICP concentrations proved to be a helpful serum marker for pedigree screening. Osteocalcin was high in 25 of 28 patients with osteogenesis imperfecta in the first decade but only in 1 of 18 older patients. Insulin-like growth factor-I was within the normal range in 53 cases of osteogenesis imperfecta, decreased in 2 and elevated in 3 patients. We conclude that PICP concentration is a useful parameter in the clinical management of osteogenesis imperfecta, including the assessment of future therapeutic interventions.

Adolescent↗
PubMed1993

Different regulation of clonal growth by transforming growth factor-beta 1 in human fetal articular and costal chondrocytes.

The variable affection of rib and limb growth in human skeletal dysplasias suggests the presence of site-specific regulatory mechanisms for chondrocyte proliferation. We therefore studied the clonal growth of normal human costal and articular chondrocytes from the same four fetuses (15 to 30 wk of gestation) in a semisolid medium (0.8% methylcellulose) with a basal supplementation of 5% heat-inactivated FCS. IGF-I[0.3-12.5 ng/mL (0.04-1.6 nmol/L)], IGF-II [0.3-12.5 ng/mL (0.04-1.7 nmol/L)], and hGH [0.5-25 ng/mL (0.02-1.1 nmol/L)] stimulated clonal growth of articular and costal chondrocytes without site-specific difference. In contrast, a significant difference was found for transforming growth factor-beta 1, which proved to be a potent growth factor for fetal articular chondrocytes but did not stimulate or only minimally stimulated fetal costal chondrocytes [p < 0.05 for 0.3 ng/mL (0.01 nmol/L) TGF-beta 1 and p < 0.01 for 1.25 ng/mL (0.05 nmol/L) TGF-beta 1 using paired t test]. Preincubation with an IGF-I receptor antibody (alpha IR-3) completely prevented the proliferative effect of IGF-I, IGF-II, and hGH, indicating that hGH acts via autocrine or paracrine induction of IGF. The antibody partly reduced TGF-beta 1 action on articular chondrocytes [p < 0.05 for 0.3 ng/mL (0.01 nmol/L) TGF-beta 1, NS for 1.25 ng/mL (0.05 nmol/L) TGF-beta 1 using paired t test]. These results indicate that TGF-beta 1 is involved in the regulation of human fetal growth and has a different effect in ribs and limbs.

Cartilage↗
PubMed1993

[Osteogenesis imperfecta in childhood and adolescence].

BACKGROUND: 209 patients with osteogenesis imperfecta type I, III and IV were studied to provide data on the natural course of the disease until the end of the second decade. RESULTS: Weight and length at birth were normal in most cases of type I and IV, markedly reduced in type III. Fractures and deformities at birth were most frequent in type III. High fracture rates occurred in type III and IV up to 8-10 years of age. Skeletal deformities developed primarily in the lower extremities and the spine, again most frequently in type III. Radiological features were--besides osteopenia--Wormian bones of the skull, pseudoarthroses, deformity of the pelvis, popcorn epiphyses (most frequent in type III) and hyperplastic callus (most frequent in type IV). Longitudinal growth of patients with type I was in the lower normal range, while patients with type III and IV developed marked growth deficiency. Motor performance was not severely impaired in most cases of type I; however, all type III patients and 71% of type IV patients were confined to a wheelchair in later life. CONCLUSION: As defined, type I patients had a mild clinical course until early adulthood. Type III and IV represented a spectrum of severely affected patients. Although type IV patients were less affected at birth, their postnatal course in some respects resembled that of type III.

Activities of Daily Living↗
PubMed1992

Collagen metabolism in cultured osteoblasts from osteogenesis imperfecta patients.

Collagen produced in vitro by bone cells isolated from 19 patients with different forms of osteogenesis imperfecta (OI) was analysed. Clinically, four patients were classified as OI type I, 10 patients as OI type III and five patients as OI type IV. Bone cells of 12 of the 19 OI patients produced structurally abnormal type I collagen. Electrophoretically uniformly slower migrating collagen type I alpha-chains were found in one case of OI type I, in seven cases of OI type III and in one case of OI type IV; two cultures of OI type III produced two different populations of collagen type I alpha-chains, and one culture of OI type IV showed reduction-sensitive dimer formation of alpha 1(I) chains, resulting from the inadequate incorporation of a cysteine residue into the triple helical domain of alpha 1(I). Quantitative analysis of collagen metabolism led to the distinction of two groups of cultured OI osteoblasts. In osteoblasts of OI type I, mainly production of collagen was decreased, whereas secretion, processing and pericellular accumulation of (pro)collagen type I was similar to that in control osteoblasts. In contrast, in osteoblasts of OI types III and IV, production as well as secretion, processing and pericellular accumulation of (pro)collagen type I were significantly decreased. Low levels of type I collagen were found irrespective of the presence or absence of structural abnormalities of collagen type I in all OI types.

Adolescent↗
PubMed1992

Osteogenesis imperfecta: a clinical study of the first ten years of life.

One hundred twenty-seven children with osteogenesis imperfecta (O.I.) were studied during the first 10 years of life. According to Sillence, 40 patients were assigned to type I, 39 to type III, and 48 to type IV O.I. Centiles for height, weight, and the annual number of fractures could be established for the different types of O.I. The development of the skeletal changes could be documented for the different forms of the disease. At birth, the skeletal changes were significantly more severe in type III than in type IV patients. During the first 10 years of life the number of fractures, extent of skeletal deformities, and growth retardation did not differ between types III and IV. Only fracture nonunion, dentinogenesis imperfecta, and congenital cardiac malformations were more frequent in type III than in type IV. Papillary calcifications of the kidney and kidney stones were diagnosed in 4 type III and 2 type IV patients. Hemihypertrophy of the body developed in 2 type I patients. Although types III and IV patients suffered from severe short stature, serum insulin-like growth factor (IGF) I was in the normal range.

Body Height↗
PubMed1992

Hyperplastic callus formation in osteogenesis imperfecta.

Osteogenesis imperfecta, an inherited disorder of connective tissues, affects roughly (OI) 4000 people in Germany (11). The main clinical symptoms are fragile bones, progressing skeletal deformities, generalized osteoporosis and short stature. Incidentally, the clinical manifestations can range from perinatal lethal forms to phenotypical normal adults. In many instances the underlying causes of the disease are mutations in gene coding for collagen I, the predominant protein in most connective tissues. Fracture healing is usually not impaired, although in a unique group of OI-patients, a tumor-like hyperplastic callus occurs with excessive deposition of extracellular matrix constituents. Biochemical analysis of the callus is reminiscent of bone from early stages of human development and normal fracture healing (e.g. collagen type composition, degree of posttranslational modification). This underlines that, besides collagen mutations, the regulation of collagen synthesis and their posttranslational processing might be disturbed in patients with hyperplastic callus formation.

Bony Callus↗
PubMed1992

Defective stimulation of proliferation and collagen biosynthesis of human bone cells by serum from diabetic patients.

We studied the influence of fasting serum from nine insulin-dependent diabetic children and adolescents under insufficient metabolic control on normal human bone cells in vitro compared with serum from eight sex- and age-matched controls. Cell number 24 h after plating was significantly less under diabetic serum, indicating impaired cell attachment, spreading and initiation of cell proliferation. Cell number after five days was reduced by 1% diabetic serum, while higher serum concentrations had diverging effects on osteoblast proliferation. Collagen synthesis of human osteoblasts was significantly reduced by 8% diabetic serum compared to 8% control serum, while synthesis of non-collagenous proteins was not affected. Duration of diabetes (several weeks up to 12 years) had no influence on these parameters. The serum from one patient, which was studied a second time under excellent metabolic control three months later, however, had lost its inhibitory influence on collagen synthesis of osteoblasts. The pattern of the interstitial collagen types I, III and V was not altered by diabetic serum. These results indicate that defective regulation of proliferation and collagen synthesis of osteoblasts by components present in human diabetic serum may be an important factor in the development of diabetic osteopenia. The negative influence might be explained in part by reduced levels of IGF-I and elevated levels of IGF binding protein-1 in the diabetic sera.

Adolescent↗
PubMed1992

Excessive collagen formation in fibrolamellar carcinoma of the liver: a morphological and biochemical study.

We have studied the excessive deposition of extracellular matrix in a patient with fibrolamellar carcinoma of the liver. The collagen matrix was predominantly composed of collagens I, III, and V. Since specific mRNAs for collagens I and III were detected by in situ hybridization, we also provide evidence that the fibroblastoid stromal cells were the major source of this collagen. Occasionally, also tumor cells could be shown to express collagen III-mRNA. Furthermore, some tumor cells showed positive signals for TGF-beta 1, while isolated stromal cells expressed interleukin-6. This cytokine expression may probably be related to the altered control of collagen gene expression.

Adolescent↗
PubMed1990

Altered collagen metabolism in osteogenesis imperfecta fibroblasts: a study on 33 patients with diverse forms.

The pattern of collagen metabolism was analysed in fibroblast cultures from patients with diverse forms of osteogenesis imperfecta (OI). Generally, OI fibroblasts show an insufficient collagen synthesis which is most obvious in patients between 2 and 9 years of age during which period control fibroblasts have an elevated collagen synthesis. OI fibroblasts remain on a basal level except for fibroblasts from OI type IV patients which seem to approach normal levels. In addition, OI fibroblasts generally show a slightly increased degradation of newly synthesized collagen which again is most obvious between 2 and 9 years. These differences in collagen degradation, however, only contribute to a minor extent to the lack of net collagen synthesis during early childhood. No correlation could be found between the degree of overmodification of collagen and its degradation since fibroblasts of both OI type I and OI type II have an elevated degradation though only the latter ones produce overmodified collagen molecules. Pulse labelling of collagen with radioactivity labelled sugars was used to distinguish between normal collagen chains or CNBr-derived peptides and those which were overmodified. In all three cases studied (OI II, OI III, OI IV) the entire triple helical domain of alpha 1(I) and alpha 2(I) was overglycosylated. The amount of overmodification, however, was not uniform but rather unique for each patient studied. We assume that the molecular defects in the majority of OI cases may be located in the mechanisms operating on the control of both the age appropriate synthesis of collagen and its degree of post-translational modification.

Cells, Cultured↗
PubMed1989

Osteogenesis imperfecta: insufficient collagen synthesis in early childhood as evidenced by analysis of compact bone and fibroblast cultures.

We analysed the composition of compact bone from 30 patients suffering from various forms of osteogenesis imperfecta (OI). Collagen and total protein content per cell of controls increased with the age of the donors, but were generally low in OI. In fibroblast cultures controls had a maximum of collagen synthesis between 2 and 9 years of age, an observation which was not seen in OI cells. In bone collagen both OI type II patients showed overhydroxylation of lysyl residues as did some patients with OI type III (25%) and OI type IV (33%). The collagen of OI type I patients was never found to be overmodified. In controls, collagen III was found exclusively during fetal time while it was present in significant amounts in bone tissue of all types of OI. The proportion of collagen V was somewhat higher in OI bones (about twice) than in controls. Our data suggest that the normal increase of collagen synthesis is defective in patients with OI. Perhaps some of these changes are due to specific molecular defects in collagen while others may be due to defective regulation of the maturation process.

Adolescent↗
PubMed1989

Biochemical analysis of callus tissue in osteogenesis imperfecta type IV. Evidence for transient overmodification in collagen types I and III.

We analyzed tissue and cells from a stationary and a rapidly growing hyperplastic callus from a patient with osteogenesis imperfecta (OI) type IV and compared the results with those of compact bone and skin fibroblasts of an age-matched control. Collagen and protein contents per cell were low in the callus tissues and collagen I and III were overmodified as evidenced by an elevated level of hydroxylysine. The degree of lysyl hydroxylation was highest in those regions that appeared most immature by histological examination. Lysyl hydroxylation approached normal levels in collagen from the stationary callus and from the center of the growing callus. Overmodification of collagen was not seen in compact bone or cell cultures (neither skin fibroblasts nor callus cells) from the patient. Elevation of hydroxylysine in collagen from OI patients is generally attributed to mutations that delay triple helix formation. Our observations suggest that the varying degree of collagen modifications may occur in consequence of regulatory mechanisms during bone development and tissue repair. These mechanisms may be defective in some patients with OI as seen in this case with hyperplastic callus formation.

Adolescent↗