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Biomedical subjects

E Ritz

Publications and source records attributed to E Ritz.

At least 991 records · Page 55Linked to original sources
PubMed1975

Structural changes of cortical bone in secondary hyperparathyroidism: replacement of lamellar bone by woven bone.

In femoral cortical bone of 16 uremic patients with long standing renal insufficiency an increased fraction of woven bone was found both in Haversian and in interstitial bone. Either partly resorbed Haversian systems were replaced by non lamellar woven bone or single Haversian systems showed partly well organized lamellar bone and partly disorganized non lamellar texture without signs of antecedent resorption. The replacement of lamellar bone by woven bone was measured morphometrically in undecalcified ground sections. Woven bone was defined by its lack of structural birefringence under polarized light. In advanced cases of secondary hyperparathyroidism more than 60% of cortical bone were composed of woven bone. The substitution of immature less organized woven bone for mature well orfanized lamellar bone has important implications for the biomechanical properties of the skeleton.

Adult↗
PubMed1975

Tumor-associated transplantation antigens in immune rejection of mouse malignant cell hybrids.

The inability of mouse cell hybrids derived from two malignant parental cells to produce tumors in syngeneic F1 hosts was analyzed. YC hybrids, derived from the fusion of C1.1D and L1210 clls, failed to induce any tumor in adult mice, while 91% of x-irradiated newborn mice developed tumors and died. Some telocentric chromosomes were lacking in hybrid tumors; however, none of the immunologically intact adult mice developed tumors when grafted with tumors grown in x-irradiated newborn mice. This indicates that histocompatibility factors interfered in the failure of YC tumors to grow to adult hosts. Syngeneic F1 mice immunized with Y2C hybrid cells had cytotoxic antibodies against Y2C hybrids and C1.1D and L1210 parental cells. Complete absorption of cytotoxic antibodies directed against hybrid cells by mixtures of both parental cell lines demonstrates the absence of any new antigen on hybrid cells.Hyb rid cells had a higher density of C1.1D-tumor antigenic sites, as compared to C1.1D parental cells. This possibly explains the higher antigenicity and/or the higher sensitivity to immune lysis of hybrid cells.

Animals↗
PubMed1975

Nonmalignancy of hybrids derived from two mouse malignant cells. II. Analysis of malignancy of LM (TK-) Cl 1D parental cells.

The possibility that Cl 1D cell line, an L-cell line derivative, was a mixture of malignant and nonmalignant cells was investigated because previous experiments showed that some hybrids derived from Cl 1D and tumor cell lines grew in vivo, whereas others apparently did not have that capacity. More highly malignant Cl 1D cells were not selected by animal passage of tumors obtained from inoculation of cultures. The tumor-producing capacity of this line (10%) was greatly increased (81%) in X-irradiated hosts. These observations suggested that the low capacity of Cl 1D cells to grow in vivo did not result from varying degrees of malignancy but mainly from interference of immunogenetic factors between cells and their inbred hosts of origin. Numerous hybrids between tumor and host cells were in all tumors examined.

Animals↗
PubMed1975

Slipped epiphyses in renal osteodystrophy.

Clinical, biochemical, roentgenological, and histological features of slipped epiphyses (epiphysiolysis) in 11 out of 112 children with renal osteodystrophy have been analysed. Characteristic age-related patterns of involvement of different epiphyses are described. Quantitative measurements of iliac bone histology, serum parathyroid hormone levels, and clinical history show the presence of more advanced osteitis fibrosa in children with epiphysiolysis than in those without. A good correlation was found between serum parathormone levels and osteoclastic resorption, endosteal fibrosis as well as osteoid. Histological studies show that the radiolucent zone between the epiphyseal ossification centre and the metaphysis in x-rays is not caused by accumulation of cartilage and chondro-osteoid (as usually found in vitamin D deficiency rickets) but by the accumulation of woven bone and/or fibrous tissue. The response to vitamin D therapy in most cases was good. Parathyroidectomy was required in only one case.

Adolescent↗
PubMed1975

Bone volume and mineral density of iliac crest spongiosa in uremia.

Bone mass and bone mineral content were measured in non-dialyzed and dialyzed uremic patients. Bone mass, measured by micromorphometry and a gas displacement method, was higher in uremic than in age and sex matched control subjects (micromorphometry-U:25.8 +/- 8.24%; Co:15.6 +/- 4.38; gas displacement-U:211 +/- 66 mm3/cm3; Co:191 +/- 45). In hemodialyzed patients, bone mass was lower the longer the patients had been on dialysis (r = 0.38; P 0.05). Bone mineral content (specific weight) was diminished in uremia (1.82 +/- 0.095 g/ml; controls 1.854 +/- 0.0173). In hemodialyzed patients, specific weight was higher, as was Ca content of bone assessed by neutron activation analysis. It is concluded, that negative Ca balance was the major cause of bone loss and that bone loss is thus preventable.

Bone Resorption↗
PubMed1975

Pathophysiology and therapy of hypercalciuria in patients who form recurrent stones.

There are two alternative mechanisms that might be responsible for idiopathic hypercalciuria in recurrent stone formers: increased intestinal absorption of calcium with parathyroid suppression and overflow hypercalciuria (primary intestinal hyperabsorption) or renal calcium leak with compensatory hyperparathyroidism and intestinal hyperabsorption (primary renal-tubular hypercalciuria). In this study, urinary excretion of cAMP, the intracellular effector substance synthetised under parathyroid hormone stimulation, was found to be in the normal range. This finding would argue against intestinal hyperabsorption of calcium as the primary cause of hypercalciuria.

Benzothiadiazines↗