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J Fallon

Publications and source records attributed to J Fallon.

29 records · Page 2Linked to original sources
PubMed1990

Evaluation of metastatic cardiac calcification in a model of chronic primary hyperparathyroidism.

Recent reports have fueled an interest in the prevalence and significance of metastatic calcium deposition in patients with chronic hyperparathyroidism. Experimental data are limited by the lack of suitable in vivo animal models. We have developed a model of marked hypercalcemia and overproduction of parathyroid hormone using somatic gene transfer. Briefly, the process involves infection of cultured rodent fibroblasts (RAT-1 cells) with a retroviral expression vector that contains the gene encoding human parathyroid hormone. Fibroblasts are grown to confluence on collagen-coated dextran microcarrier beads and are injected into the peritoneal cavities of syngeneic Fisher rats. Human parathyroid hormone production in rat serum is quantified by an immunoradiometric assay for human parathyroid hormone (1-84), which does not recognize rat parathyroid hormone. These rats consistently show production of human hormone within a week. Levels increase progressively, often to 1 ng/ml within 60 days of injection. Serum calcium showed a concomitant rise to an average of 15.5 mg/dl. In this study, 13 rats that had been transplanted with parathyroid hormone-producing fibroblasts were killed 80 days after injection. Examination of the skeleton revealed demineralization and histopathologic sequelae of parathyroid hormone excess with extensive osteoclastic bone resorption. Examination of the hearts revealed calcification in five of 13 hearts. There was no involvement of major coronary arteries or conducting systems, but there was calcification of cardiac myocytes, primarily in subepicardial region. This model may permit an understanding of the mechanisms for sudden cardiac death in severe hypercalcemia.

Animals↗
PubMed1989

Collateralization and GAD immunoreactivity of descending pallidal efferents.

The first phase of this study involves injecting a different fluorescent retrograde axonal tracer into the subthalamic nucleus, the substantia nigra, and the mesopontine tegmentum. Multiple labeled cells are found within the caudal third of the globus pallidus. The entopeduncular nucleus and adjacent basal forebrain structures such as the substantia innominata, lateral hypothalamus, bed nucleus of the stria terminalis, and central nucleus of the amygdala all exhibit some dye containing cell, although multiple labeled cells are rare. The second phase of this study involves injecting a different fluorescent retrograde tracer into either the substantia nigra, or the mesopontine tegmentum, and subsequent processing of the tissue for glutamic acid decarboxylase (GAD) immunocytochemistry. Many dye and antibody double-labeled cells could be found within the entopeduncular nucleus and the caudal third of the globus pallidus. This is in contrast to the surrounding basal forebrain regions with brainstem efferents which were rarely GAD-positive. This study indicates that the collateral pattern and immunocytochemistry of globus pallidus neurons with descending efferents are distinct from other basal forebrain neurons having similar efferents. These results also extend previous findings and suggest that the neuron of the pallidal complex are heterogeneous with respect to their patterns of projections. In particular, the present findings question previous assumptions concerning the homology of pallidal segments between primate and rodent species.

Animals↗
PubMed1986

End-to-end versus end-to-side microvascular anastomosis patency in experimental venous repairs.

In this experimental study, venous end-to-end and end-to-side microvascular anastomoses in similar and diameter-discrepant vessels were compared. In 50 rats, end-to-end microvascular repair of the divided epigastric vein and end-to-side repair of the epigastric vein into the femoral vein showed 5-day patency rates of 75 and 88 percent, respectively. These data are not statistically different. In 20 rats, microvascular repair of end epigastric to end femoral veins (size discrepant) and end epigastric to side femoral veins showed 5-day patency rates of 50 and 85 percent, respectively. These data are statistically different (p less than 0.05). We conclude from these experimental data that end-to-side venous repairs may be useful in lowering the anastomosis thrombosis rate seen when size-discrepant veins are repaired.

Animals↗
PubMed1982

Current PTFE grafts: a biomechanical, scanning electron, and light microscopic evaluation.

Two currently available brands of PTFE grafts (Goretex and Impra) were studied in a canine femoral artery model to determine whether changes in the manufacturing processes of the two grafts, which increased their strength, had altered the biophysical properties and the histological reactivity of either graft. Both grafts were found to be similar except for differences in their suturability. Their in vivo dynamic compliances were almost identical (1.2 +/- 0.35 vs. 1.2 +/- 0.45). (Scanning electron microscopy showed endothelialization of the grafts only adjacent to the anastomoses, and light microscopy demonstrated similar degrees of histologic incorporation by the host tissues, though of slower tempo than that previously described. These results are examined and discussed with regard to the suitability of this model for characterizing new arterial prostheses of small to medium diameter.

Animals↗
PubMed1982

Relationship between alveolar bone measured by 125I absorptiometry with analysis of standardized radiographs: 1. Magiscan.

PREVIOUS STUDIES have shown that 125I absorptiometry gives an accurate and sensitive measure of alveolar bone mass. The purpose of this study was to determine the relationship between alveolar bone mass determined by 125I absorptiometry and bone density obtained by analysis of standardized intraoral radiographs by the Magiscan System. A defect of increasing size was made at one site of the alveolar bone in a human skull. The amount of bone remaining at each step was calculated using 125I absorptiometry. Standardized radiographs were also taken at each step and the relative density in the area of the defect was determined by the Magiscan System. The Magiscan's System Computer Memory permits analysis of identical areas on a longitudinal series of films of the same alveolar bone location. The results indicate that in estimating amounts of alveolar bone the Magiscan analysis of standardized intraoral radiography is similar in sensitivity and accuracy to 125I absorptiometry.

Absorption↗
PubMed1980

Observations on the "cytoskeleton" of human platelets.

Structural study of rapidly lysed platelets supports the view that that shape change involves a change in state of the microfilaments which contain actin. The microtubule "bundle" appears to be a continuous coil. Proteolysis of a high molecular weight band is observed in platelets which can no longer form filopodia after suppression by local anesthetics.

Blood Platelets↗
PubMed1980

Dose reduction and discontinuation of antipsychotic medication.

In 1977 staff members on a 30-bed inpatient ward in a state hospital implemented a program to discontinue the medication of chronic schizophrenic patients who had been hospitalized continuously for five years or more. Six-month follow-up of the 15 patients who met the selection criteria showed that seven were still off medication, and two had improved enough to be discharged. The program was later adopted throughout the hospital; an audit conducted 90 days after its implementation showed that 31 per cent of the patients hospitalized continuously for 90 days or longer were not receiving antipsychotic medication. The authors emphasize the benefits to patients of reducing or discontinuing antipsychotic medication where possible.

Adult↗
PubMedDate not supplied

Planimetry study of the percent of body surface represented by the hand and palm: sizing irregular burns is more accurately done with the palm.

Sizing irregular burns is commonly done with use of the patient's hand as a template representing 1% of the body surface. To verify that this is accurate over a broad range of ages or to see if the surface of the palm is a more consistent template, a planimetry study was done. This revealed that the surface area of the palm averaged 0.52% total body surface area (+/- 0.07) and the palmar surface of the hand 0.85% total body surface area (+/- 0.08). The surface of the palm was a more consistent template and represented 0.5% of the body surface over a broad range of ages.

Adolescent↗