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Biomedical subjects

P Wild

Publications and source records attributed to P Wild.

At least 127 records · Page 7Linked to original sources
PubMed1981

Fibroblast traction as a mechanism for collagen morphogenesis.

To make visible the traction forces exerted by individuals cells, we have previously developed a method of culturing them on thin distortable sheets of silicone rubber. We have now used this method to compare the forces exerted by various differentiated cell types and have examined the effects of cellular traction on re-precipitated collagen-matrices. We find that the strength of cellular traction differs greatly between cell types and this traction is paradoxically weakest in the most mobile and invasive cells (leukocytes and nerve growth cones). Untransformed fibroblasts exert forces very much larger than those actually needed for locomotion. This strong traction distorts collagen gels dramatically, creating patterns similar to tendons and organ capsules. We propose that this morphogenetic rearrangement of extracellular matrices is the primary function of fibroblast traction and explains its excessive strength.

Animals↗
PubMed1980

Silicone rubber substrata: a new wrinkle in the study of cell locomotion.

When tissue cells are cultured on very thin sheets of cross-linked silicone fluid, the traction forces the cells exert are made visible as elastic distortion and wrinkling of this substratum. Around explants this pattern of wrinkling closely resembles the "center effects" long observed in plasma clots and traditionally attributed to dehydration shrinkage.

Animals↗
PubMed1980

Correlative light- and electron-microscopic study of parathyroid glands in dogs of different age groups.

The parenchyma of parathyroid (PT) glands of neonatal, growing and adult dogs consisted of dark and light chief cells. In growing and adult dogs, dark chief cells had an electron-dense cytoplasm, prominent rough endoplasmic reticulum (rER) and Golgi apparatus. Based on the secretion cycle proposed by Roth and Capen [1974], they were referred to as active cells. Light chief cells had an electronlucent cytoplasm, inconspicuous rER and Golgi apparatus. They were referred to as inactive cells in resting stages or in stages of transition between active and inactive forms or vice versa. In neonatal dogs, dark chief cells were similar to those in growing and adult dogs and light chief cells had the features of the cells referred to as cells in transitional stages. There were no cells in resting stages. The morphological findings suggest that PT activity in growing dogs was similar to that in adult dogs, whereas in neonatal dogs it was different; this may be related to the animal's developmental status or to changes in serum calcium concentration after birth.

Aging↗
PubMed1980

Morphometric analysis of parathyroid glands in neonatal and growing dogs.

In dogs and aged 6 days or 5 months, the parathyroid (PT) glands exhibited differences of both the distribution and ultrastructure of dark and light cells. Morphometric estimates of cytoplasm, nucleus, mitochondria, rough endoplasmic reticulum (rER), Golgi apparatus, secretory granules, lysosomes and plasma membranes of both dark and light cells were obtained by point counting volumetry from PT glands of dogs of the two age groups and calculated per one hypothetical average PT cell. It was evident that in the PT glands of 6-day-old puppies the volume of the average PT cell was significantly smaller than in the PT glands of the 5-month-old dogs, but the cell surface was not significantly different. The volume of mitochondria, rER and lysosomes was higher in the average PT cell of the 5-month-old dogs, whereas the surface of Golgi apparatus and rER did not differ. Though the difference of the cellular and mitochondrial volume is probably related to the age difference between the two groups, the findings on Golgi apparatus, plasma membranes and lysosomes suggest that the secretory activity or at least the potency for the secretion of parathyroid hormone was higher in PT glands of the 6-day-old dogs than in the 5-month-old dogs.

Animals↗
PubMed1980

Response of dog parathyroid glands to short-term alterations of serum calcium.

Parathyroid (PT) glands of dogs were exposed to low or high serum calcium by infusion of either EGTA or CaCl2. Infusion of EGTA resulted in an increase of parathyroid hormone (PTH) and infusion of CaCl2, in a decrease of this hormone. The PT glands excised either at the beginning or at the end of the infusions were examined by electron microsoopy. After infusion of EGTA, activated cells showed a dense matrix, prominent Golgi apparatus, rough endoplasmic reticulum (rER) with narrow cisternae, and an incrased tortuosity of the plasma membrane, accompanied by an enlargement of the intercellular spaces. Infusion of CaCl2 resulted in a distention of the rER cisternae, disorganization of the Golgi apparatus and a decreased tortuosity of the plasma membrane. It is concluded that (1) PT cells may contract in the course of activation; (2) storage capacity for PTH is low, and (3) PT cells may be stimulated or inhibited to promote biosynthesis of PTH within minutes.

Animals↗
PubMed1979

Mitochondrial calcium uptake during infection of chicken embryo cells with Semliki Forest virus.

The key role of the mitochondria in the regulation of cellular Ca2+ led to a study of mitochondrial Ca2+ uptake during the infection of chicken embryo cells with Semliki Forest virus. Mitochondrial Ca2+ uptake was stimulated during the first 5 h of infection but declined later in infection. The early stimulation suggests an increase of cytoplasmic ionized Ca2+, whereas the later decrease indicates mitochondrial injury. This functional deterioration was correlated with an increase of the permeability of the inner mitochondrial membrane. Polarographic experiments showed that electron transport is impaired, whereas transduction of energy to Ca2+ uptake is intact.

Calcium↗
PubMed1979

Identification of immunoreactive sites in bovine parathyroid cells to antibodies raised against the NH2-terminal sequence of parathyroid hormone.

The NH2-terminal sequence of bovine parathyroid hormone (1-84) was localized with different immunocytochemical methods on the light and electron microscopic level in bovine parathyroid glands and in isolated bovine parathyroid parenchymal cells. The peroxidase labeled staphylococcal protein A and the peroxidase anti-peroxidase method were found to be advantageous for light and electron microscopic localization, respectively. Reaction product was found light microscopically in the cytoplasma of the parenchymal cells and electron microscopically largely over the secretion granules of the parenchymal cells. The immunoreactive sites were subsequently identified to represent only intact parathyroid hormone (1-84) by gel electrophoresis derived enzyme linked immunosorbent assay.

Animals↗
PubMed1978

Systemic cartilage defect in a calf.

A 6-month-old Ayrshire calf had a systemic growth defect of cartilage. The most severe changes occurred in articular cartilage and epiphyseal plates of long bones where disturbance of ossification, necrosis, erosion, vascular invasion, proliferation of cartilaginous and fibrous tissue were seen. The lesions probably were the result of a failure in the initial phases of ossification and mechanical pressure was responsible for their severity in the cartilage of the limbs.

Animals↗
PubMed1975

[Systemic cutaneous and subcutaneous amyloidosis in the horse].

A 9-year-old horse had numerous firm, painless nodules of the skin and subcutis. Moderately vascular granulation tissue with numerous uni- or multinuclear reticuloendothelial cells was in the nodules and the regional lymph nodes but not in the viscera. By using special stains and electron microscopy, widespread amyloid deposits, mainly in the cytoplasm of reticuloendothelial cells, were identified. Amyloid was probably produced within the reticuloendothelial cells, then expelled from the dying cell and deposited in the intercellular space.

Amyloidosis↗