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Biomedical subjects

L Boquist

Publications and source records attributed to L Boquist.

At least 19 recordsLinked to original sources
PubMed1990

Chronic achilles paratenonitis with tendinosis: an experimental model in the rabbit.

An experimental model for inducing chronic Achilles paratenonitis with tendinosis in the rabbit is presented. Thirteen rabbits were exercised in a kicking machine producing passive flexions and extensions of the ankle joint. Active contractions of the triceps surae muscles were induced by electric stimulation via surface electrodes. The animals were exercised for 5 to 6 weeks, with a rate of 150 flexions and extensions per minute for 2 h, three times a week. Light microscopic examination showed degenerative changes of the tendon, and increased number of capillaries, infiltrates of inflammatory cells, edema, and fibrosis in the paratenon. We conclude that chronic Achilles paratenonitis with tendinosis can be experimentally induced in a standardized manner in rabbits.

Achilles Tendon↗
PubMed1990

Kinetics of proteoglycans and cells in growth plate of normal, diabetic, and malnourished rats.

The metabolism of proteoglycans in normal growth plate and the changes in growth plate morphology induced by diabetes and malnutrition were studied in rats. The proteoglycans had a significantly faster turnover (half-life measured with [35S]sulfate labeling: 25-30 h) than the cells in the growth plate. Morphometric studies showed significant reductions of cell number, zone height, and [3H]thymidine incorporation in growth plates from rats with untreated streptozotocin-induced diabetes compared to normal rats. Similar, although less pronounced alterations were observed in malnourished, nondiabetic rats. Disaggregation and degradation of proteoglycans are probably necessary prerequisites for calcification. Our data indicate that the proteoglycans are in a dynamic state of rapid biosynthesis and degradation throughout the growth plate with a shift in the balance at the calcification front toward less synthesis and more degradation.

Animals↗
PubMed1989

Effects of sodium nitroprusside on blood glucose concentration, B-cell morphology and islet glutamate dehydrogenase activity in mice.

Mice injected with sodium nitroprusside (NaNP) exhibited a marked, transient hyperglycemia and enhanced activity of glutamate dehydrogenase in the pancreatic islets. Ultrastructurally, the islet B-cells of NaNP-treated mice showed expanded granular endoplasmic reticulum, prominent Golgi complex, increased amount of secretory granules, mitochondrial enlargement and vacuolation, and mitochondrion-secretory granule complexes. Stereological analyses disclosed increased volume of endoplasmic reticulum, Golgi complex and mitochondria, and increased number of secretory granules in the B-cells 1 h after the injection of NaNP. Isolated mouse islets exposed to NaNP showed stimulated activity of glutamate dehydrogenase both in the presence of 2 and 18 mM glucose, whereas the release of insulin was stimulated at 2 mM glucose, but inhibited at 18 mM glucose. The observations demonstrate that NaNP induces transiently altered structure and function in mouse islet B-cells.

Animals↗
PubMed1989

Inhibition by acetylsalicylate of the hyperglycemic response induced in mice by sodium nitroprusside.

The injection of sodium nitroprusside (SNP) into mice induced a hyperglycemic response which was reduced by pretreatment with acetylsalicylate (ASA). The activity of glutamate dehydrogenase was significantly increased in islets from pancreases removed after SNP injection. This effect was prevented by pretreatment with ASA. Isolated mouse islets incubated with SNP exhibited stimulated activity of glutamate dehydrogenase both in the presence of low and high glucose concentrations, whereas the release of insulin was stimulated at low but inhibited at high glucose concentrations. These changes were abolished in the additional presence of ASA. The findings indicate that the hyperglycemic action of SNP may be related to changes in the generation of cyclooxygenase products.

Animals↗
PubMed1986

Inhibition by streptozotocin of the activity of succinyl-CoA synthetase in vitro and in vivo.

The activity of succinyl-CoA synthetase from mouse liver and kidney was inhibited by streptozotocin in vitro. Streptozotocin behaved essentially as a non-competitive inhibitor, and the following kinetic values were obtained (in the presence of 10 nM streptozotocin): apparent Km 1.7 mM, apparent Ki 10 nM, and kcat 440 nkat X kg-1. Compared with non-diabetic control mice, the succinyl-CoA synthetase activity was significantly decreased in the islets and kidneys of mice with early (1 h) and manifest (greater than or equal to 2 days) streptozotocin diabetes, whereas the activity in the liver was not significantly altered. Inhibited succinyl-CoA synthetase activity is believed to play a prominent role in the cellular effects of streptozotocin.

Animals↗
PubMed1986

Factors affecting Ca2+ transport in mouse islet and kidney mitochondria.

The transport of Ca2+ in islet and kidney mitochondria respiring on succinate was inhibited by atractylate and fluorocitrate, and stimulated by pyruvate, isocitrate, alpha-ketoglutarate, dibutyryl cAMP, oligomycin and bongkrekate, and by in vivo administration of glucagon, glyceraldehyde or glucose. The kidney [beta-hydroxybutyrate]/[acetoacetate] ratio was increased in glyceraldehyde treated mice. The data suggest a relationship, which might be influenced by cAMP, between activity of pyruvate, isocitrate and alpha-ketoglutarate dehydrogenases and transport of Ca2+ in islet and kidney mitochondria. A contributory role of reductive carboxylation for Ca2+ uptake, and a role of citrate for Ca2+ retention are discussed.

Animals↗
PubMed1985

Quantitative morphological assessment of parathyroid activity in response to variations in calcium concentration in vitro.

Isolated parathyroid glands from gerbils incubated at low (0.5 mM), normal (1.25 mM) or high (3 mM) calcium concentration for 1 or 6 h were studied with regard to the following stereological parameters: the volume densities of the nucleus, mitochondria, endoplasmic reticulum, Golgi zone, lipid bodies, lysosomes, secretory granules and storage granules, and the surface densities of the cell membrane and endoplasmic reticulum. In glands incubated for 1 h no significant differences were seen between the experimental groups in any of the parameters investigated, however, the volume density of the Golgi zone and the surface density of the cell membrane were significantly increased in glands incubated for 6 h at low calcium concentration, compared with those incubated at high calcium concentration. The enlargement of the Golgi zone in stimulated glands was also evident when the two glands from the same animal incubated at different calcium concentrations were compared. The data suggest that the early response of parathyroid glands to altered concentration of extracellular calcium includes functional activities associated with the Golgi zone.

Animals↗
PubMed1979

Experimental study of follicle formation in suppressed parathyroid glands of Mongolian gerbils.

Parathyroid follicle formation was studied in Mongolian gerbils subjected to different concentrations of calcium in vivo and in vitro, using light and electron microscopic methods, including the potassium pyroantimonate technique and x-ray microanalysis for identification of cations. Follicles were frequent at high calcium concentration, but sparse at intermediate and low levels of calcium. Two main types of follicle were differentiated: "degenerative follicles" containing cellular debris and lined by smooth-surfaced epithelium which occasionally showed degenerative changes; and "secretory follicles" characterized by amorphous and granular contents, and an epithelium possessing microvilli and cytoplasmic projections. Amorphous masses were also seen in dilated intercellular spaces and in dilated cisterns of rough endoplasmic reticulum in the follicle epithelium. Calcium-containing precipitates were found in degenerating chief cells, and between degenerating cells and follicles. Parathyroid follicles are believed to be formed by degeneration of suppressed chief cells (degenerative follicles), and by secretion of hormonal and/or other substances into dilated intercellular spaces which progressively increase in size to form follicular cavities (secretory follicles), thereby possibly reducing the level of metabolically active parathyroid hormone. Functional suppression is believed to underlie the development of parathyroid follicles.

Animals↗
PubMed1979

Stereological study of B-cell mitochondria in alloxan-treated mice.

Using stereological techniques, including semi-automatic image analysis, the B-cell mitochondria were studied in the pancreatic islets from one group of control mice and two groups of mice killed 10 min and 60 min, respectively, after alloxan administration. Ten min following alloxan the mitochondrial volume and envelope surface densities, the mean mitochondrial volume and surface area, and the area of mitochondrial profiles were significantly increased, whereas the mitochondrial numerical density was not significantly altered. At the 60 min observation time the mitochondrial volume density, the mean mitochondrial volume and surface areas, and the area of mitochondrial profiles were significantly decreased, whereas the mitochondrial envelope surface was not significantly altered. The findings indicate a rapid swelling, followed by disintegration of the mitochondria in the B-cells of alloxan-treated mice, thereby supporting our view that mitochondrial lesions play a primary role in the development of alloxan diabetes. These lesions are believed to be due to ionic alterations in the B-cells ("Pi-pH hypothesis").

Alloxan↗
PubMed1979

Stereological study of endoplasmic reticulum, Golgi complex and secretory granules in the B-cells of normal and alloxan-treated mice.

Different B-cell organelles (lamellar and vesicular endoplasmic reticulum, Golgi complex, whole secretory granules and secretory granule cores) were studied stereologically in pancreatic islets from control mice and mice killed 10 or 60 min following alloxan injection. Ten min following alloxan a significant decrease was observed in the volume, surface and numerical densities of whole secretory granules and their cores, and a significant increase was found in the volume and surface densities of vesicular endoplasmic reticulum. At the 60 min observation time, a significant decrease was seen in the volume density of lamellar endoplasmic reticulum and Golgi complex, and in the volume, surface and numerical densities of whole secretory granules and their cores, and a significant increase was observed in the volume and surface densities of vesicular endoplasmic reticulum, and in the mean values for volume and surface of whole secretory granules and their cores. The stereological data indicate swelling of endoplasmic reticulum, decreased Golgi area, and decreased number and total volume and surface of secretory granules during the first hour after alloxan administration to mice. The observations may be consistent with inhibited insulin synthesis.

Alloxan↗
PubMed1979

Carbonic anhydrase activity in mouse endocrine pancreas.

Histochemical staining for carbonic anhydrase (CAH) was demonstrated in the mouse pancreas. Light microscopically, a strong reaction for CAH was found in the B-cell region of the islets, in blood vessels inside and outside the islets, and in centroacinar cells and ductules. In contrast, no distinct reaction was seen in the peripheral A- and D-cell regions of the islets, or in the cytoplasm of the acinar cells. A weak, irregular staining could, however, be observed in some nuclei of the acinar parenchyma. A newly-developed ultrastructural modification disclosed a distinct reaction in a varying number of the secretory granules of the B-cells, whereas a sparse, irregularly-distributed reaction was observed in the nuclei and cytoplasmic ground substance, and in association to the plasma membranes and microvilli of these cells. The CAH reaction was in all portions of the pancreas abolished by acetazolamide. The specificity of these results is discussed. The findings are suggested to indicate presence of a true CAH activity in the B-cells of the mouse pancreas.

Animals↗
PubMed1979

Extra-osseous osteosarcoma: a clinical and histopathological study of four cases.

Four cases of extra-osseous osteosarcoma were found among 242 cases recorded as osteosarcoma in the Swedish Cancer Registry during the years 1958 to 1968. The tumours occurred in middle-aged and elderly patients. Three of the tumours were situated in the proximal part of the thigh and one in the scapular region. Histopathologically, all tumours were subclassified as osteoblastic osteosarcomas. The patients were treated by primary local excision which in one case was followed by a radical en bloc excision of the entire tumour bed. All cases subjected to simple excision died of metastatic disease five to twenty-four months after diagnosis. The patient treated by en bloc excision is alive and apparently free from disease fourteen years after diagnosis.

Adult↗
PubMed1979

Laryngeal chondrosarcoma in Sweden.

Between 1958 and 1972, 5 cases of posterior cricoid chondrosarcoma were reported to the Swedish Cancer Registry. These cases, and one recently observed case of laryngeal chondrosarcoma, are presented in this study of one female and five male patients. The tumours grow slowly and recur locally, but have not metastasized, and none of the patients has died from tumour disease. The clinical and morphological findings indicate that these tumours represent secondary chondrosarcomas developing from pre-existing benign ecchondromas. The reason for the uniformity as to localization is not known. The microscopic appearance varied in different parts of the same tumour. The presently obtained data and review of the literature indicate that laryngeal chondrosarcomas are extremely rare, locally invasive, but usually not metastasizing tumours. Conservative laryngeal operation is suggested as primary treatment. Total laryngectomy is necessary only after local recurrences involving a major portion of the cricoid cartilage.

Aged↗
PubMed1979

Transplantable osteosarcoma in mice. Structural characterization of a transplantable osteosarcoma obtained in an allogenic system.

Light microscopic, histochemical and ultrastructural studies of a transplantable mouse osteosarcoma were carried out. The osteosarcoma grew in CBA mice after injection of cultured cells derived from a Dunn osteosarcoma. The tumour differed from the original Dunn osteosarcoma with respect to metastatic potential and structural features. The transplantable tumour was an anaplastic, richly vascularized fibroblastic osteosarcoma with alkaline phosphatase activity and rather sparse osteoid formation, resulting in death of the animals within 6 to 8 weeks. Virus particles were found intracellularly, mainly localized to cisterns of rough endoplasmic reticulum, and extracellularly often close to plasma membranes and collagen fibres. Sign suggestive of formation of collagen fibres by tumour cells were observed. A possible viral influence upon the tumour was suggested also by its growth behaviour in vitro. The results indicate that this new transplantable tumour, obtained in an allogenic system, represents a clonal derivative of the original Dunn osteosarcoma.

Animals↗
PubMed1979

Mitochondrion-secretory granules complexes in pancreatic islet B-cells.

Mitochondrion-Secretory Granule Complexes (MSGC) are present in rodent pancreatic islet B-cells, characteristically showing fusion of mitochondria and secretory granules, absence of granule membrane and external mitochondrial membrane at place of contact, often invagination of internal mitochondrial membrane at place of contact forming an electron lucent space directly continuous with the "halo" of the secretory granules, and occurrence of potassium pyroantimonate precipitates in either or both of mitochondria and secretory granules. The MSGC are believed to possess functional significance, possibly playing a role in translocation of ions between mitochondria and secretory granules in the B-cells.

Animals↗
PubMed1979

Influence of 1,25-dihydroxycholecalciferol on parathyroid activity in patients with primary hyperparathyroidism.

Parathyroid morphology and blood chemistry were studied in five patients with primary hyperparathyroidism treated with 1,25-dihydroxycholecalciferol (1,25-DHCC) for 2 to 11 days before planned operation. Before the institution of treatment all patients were hypercalcemic, whereas the serum immunoreactive parathyroid hormone (iPTH) concentration either was elevated or normal. During the treatment the urinary phosphate excretion was significantly increased, whereas the calcium excretion and the serum concentrations of calcium and phosphate were unaffected or only slightly changed. Serum iPTH decreased during the first days of treatment, but returned then to increased levels close to the pretreatment ones. The treatment was tolerated well by the patients. Light and electron microscopy of the removed parathyroid glands disclosed one adenoma in each of the five patients, the other glands exhibiting either a slight hyperplasia or a normal appearance. Both the adenomatous and the non-adenomatous parathyroid tissue showed a predominance of dark chief cells and three of the adenomas exhibited a varying number of atrophic and oxyphil cells. The non-adenomatous glands were composed of atrophic and dark chief cells. Signs of low functional activity were ultrastructurally observed in the parathyroid parenchymal cells. It is suggested that 1,25-DHCC treatment of patients with primary hyperparathyroidism inhibits parathyroid hormone secretion.

Adult↗
PubMed1979

Structural changes in parathyroid glands exposed to vitamin D metabolites in vitro.

Isolated parathyroid glands from normal adult Mongolian gerbils were incubated for 10 minutes to 16 1/2 hours at high, medium or low concentrations of Ca2+, with or without added 1,25-dihydroxycholecalciferol (1.25-DHCC) or 25-hydroxycholecalciferol (25-HCC), after which they were studied electron microscopically. 1,25-DHCC appeared to potentiate the inhibitory action of high calcium on parathyroid activity, whereas 25-HCC had no structurally detectable effect.

Animals↗