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Biomedical subjects

C R Thomas

Publications and source records attributed to C R Thomas.

137 records · Page 8Linked to original sources
PubMed1975

Capillary density in developing and healing tuberculous lesions produced by BCG in rabbits. A quantitative study.

Dermal tuberculous lesions were produced in rabbits by the intradermal injection of BCG. At various times after infection, anesthetized animals were perfused with a gelatin-colloidal carbon medium via the abdominal aorta. The capillary density of the nonnecrotic granulation tissue in the lesions was determined quantitatively by counting the capillaries under an ocular grid of a microscope. The capillary density in normal skin near the lesions was 3.8 plus or minus 0.5 in millimetersof capillary lengths per square millimeter in 250-mu tissue sections. The capillary density of the nonnecrotic tissue in BCGlesions averaged 6.1 plus or minus 0.6 mm/sq mm, an increase of 60%. The capillary density remained more or less constant as the BCG lesions grew and then regressed. The development of delayed hypersensitivity seemed to increase the capillary density, but this increase may have been a response to an extension of the necrosis at the time delayed hypersensitivity developed. Capillary densities in tuberculin reactions resembled those in BCG lesions. In the early stages, the increaseed capillary network of dermal BCG lesions was derived mainly from the subpapillary vascular plexus of the deep dermis supplied branches that surrounded the lower half of the caseous necrotic center and anastomosed with capillaries from the subpapillary plexus supplying the upper half. When the necrotic center extended, nearby capillaries thrombosed and in turn became necrotic. Peripherally, new capillaries formed and anastomosed with existing capillaries. From these vessels, mononuclear phagocytes emigrated, destroyed the tubercle bacilli, and enabled the lesion to heal. In the BCG lesions at all stages of development and healing, the capillary network in the nonnecrotic areas seemed adequate to supply and nourish the defense cells controlling the infection.

Animals↗
PubMedDate not supplied

In vitro potentiation of the activity of synthetic ovine corticotropin-releasing factor by arginine vasopressin.

The ability of arginine vasopressin (AVP) to potentiate the actions of synthetic ovine corticotropin-releasing factor (CRF) was examined using anterior pituitary fragments. Marked potentiation of ACTH release was observed upon incubating the fragments with a combination of 2 nM AVP and 1 nM CRF. Potentiation of CRF-induced ACTH release was also observed when the fragments were incubated with a combination of 1 nM AVP and 0.5 nM CRF. These results suggest that AVP may play a role in the release of ACTH from the adenohypophysis.

Adrenocorticotropic Hormone↗
PubMedDate not supplied

In vitro pituitary hormone releasing activity of 40 residue human pancreatic tumor growth hormone releasing factor.

The hypophysiotropic activities of a synthetic human pancreatic growth hormone releasing factor (hpGRF) with 40 residues was examined in vitro using rat pituitary halves. At concentrations from 10(-10) M to 10(-7) M the peptide stimulated GH release in a dose-dependent manner with the ED50 being 1.2 x 10(-9) M. The concentration of 10(-10) M hpGRF is comparable to the basal hypophyseal portal blood levels of other known hypothalamic hypophysiotropic hormones. However, GH release was enhanced three-fold by concentration as low as 10(-12) M, though no dose-response relationship was observed up to 10(-10) M. Thus, this peptide not only stimulates the release of GH in a dose-dependent manner, but at lower concentrations also maintains elevated GH levels. The release of ACTH, beta-endorphin, LH, and FSH was not affected by hpGRF at any of the concentrations tested. At hpGRF concentrations less than 10(-7) M, the release of TSH and PRL were unaffected. However, at 10(-6) M, TSH release was enhanced about 2.5 fold and prolactin release was elevated slightly.

Animals↗
PubMedDate not supplied

Immunocytochemical localization of growth hormone releasing factor (GHRF)-containing structures in the rat brain using anti-rat GHRF serum.

The distribution of growth hormone releasing factor (GHRF) immunoreactive structures in the rat hypothalmus was studied after colchicine treatment with PAP immunocytochemistry in vibratome sections using an antiserum directed to rat hypothalamic GHRF. The majority of the GHRF-immunoreactive cell bodies were found in the arcuate nucleus, the medial perifornical region, and the ventral premammillary nuclei of the hypothalamus. Scattered cells were seen in the lateral basal hypothalamus, the medial and lateral portions of the ventromedial nucleus, and the dorsomedial and paraventricular nuclei. Immunoreactive fibers were observed in all the regions mentioned above. GHRF terminals were located in the central region of the median eminence. In addition, GHRF-immunoreactive neuronal processes were seen in the ventral region of the dorsomedial nucleus, the medial preoptic and suprachiasmatic regions, dorsal portion of the suprachiasmatic nucleus, bed nucleus of the stria terminals and the hypothalamic portion of the stria terminals. The localization of GHRF-immunoreactive terminals in the median eminence reinforces the view that GHRF plays a physiological role in the regulation of pituitary function. In addition, the localization of GHRF-immunoreactive structures in areas not usually considered to project to the median eminence suggest that GHRF may act as a neuromodulator or neurotransmitter.

Animals↗
PubMedDate not supplied

The assessment of gestational age and litter size in the guinea pig using a radiographic method.

The gestational age and litter size in the guinea pig can be accurately assessed by taking an x-ray of the animal. From a measurement of the fetal head length on the x-ray plate a fetal weight can be calculated using previously accumulated data, included here. The gestational age can be assessed from this weight to within +/- two days, using the fetal growth data of Draper (1920), Eckstein, McKeown and Record (1955) and Ibsen (1928). The litter size can be readily ascertained from the x-ray plate.

Animals↗
PubMedDate not supplied

Ten-year follow-up of Southwest Oncology Group 8269: a phase II trial of concomitant cisplatin-etoposide and daily thoracic radiotherapy in limited small-cell lung cancer.

PURPOSE: To report the long-term follow-up of Southwest Oncology Group-8269, a phase II North American cooperative group trial of concurrent cisplatin, etoposide, vincristine (PEV), and thoracic radiotherapy (TRT) for limited small-cell lung cancer (L-SCLC). METHODS: 114 eligible patients from 47 institutions enrolled between April, 1985 and March 1986. Patients had documented L-SCLC. Induction chemotherapy consisted of three cycles of PEV. TRT was administered at 1.8 Gy/fraction in 25 daily fractions to a total dose of 45 Gy, to begin concomitantly. Consolidative chemotherapy included two cycles of vincristine, methotrexate, etoposide, doxorubicin and cyclophosphamide. Prophylactic cranial irradiation (PCI) was concurrent with the 3rd cycle of chemotherapy. The PCI dose was 30 Gy in 15 fractions of 2 Gy/fraction. RESULTS: As of May 2000, 5 of 114 remain alive and progression-free with a minimum follow-up interval of 13.2 years, as of May 2000. The median follow-up interval is 14.2 years. Thirty eight patients died of causes other than SCLC and five patients are still alive and progression-free. Of the remaining 71 patients dying of SCLC, local failure (LF) occurred in 24% (17 patients), distant metastasis (DM) occurred in 35% (25 patients), simultaneous LF and DM occurred in 25% (18 patients), and was indeterminate in 16% (11 patients). Thus, LF was a component of failure in 49%. Twenty patients had the CNS as the initial site of failure. Eleven patients (10%) developed fatal second primary cancers, including two with acute myelogenous leukemia, two with squamous cell lung cancer, one each with breast, pancreas, prostate, renal cell, and myelodysplasia. One patient developed both a melanoma and non-Hodgkin's lymphoma. CONCLUSION: There are long-term survivors with concomitant TRT and PEV. LF and DM are common. Pattern of failure suggests needs to improve local and systemic control.

Antineoplastic Combined Chemotherapy Protocols↗
PubMedDate not supplied

Mechanical strength of single microcapsules determined by a novel micromanipulation technique.

A micromanipulation technique has been developed to measure the bursting force of single dry microcapsules coated onto a surface, such as those normally used in carbonless copying paper. For measuring the bursting force of a given microcapsule, a single fine probe with a flat end about 10 microns in diameter was used to squeeze the microcapsule against a flat surface until it burst. The force being imposed on the microcapsule was measured by a transducer connected to the probe. The bursting force and diameter of single dry microcapsules in two samples, different in size and wall thickness, were measured by this technique. The bursting force of the microcapsules in one sample ranged from 50 to 220 microN and the diameter from 1.3 to 7.0 microns, whilst the bursting force in the other was from 20 to 175 microN and the diameter from 0.7 to 3.7 microns. This technique makes it possible to compare the mechanical strength of microcapsules made of different formulations, and to infer information about microcapsule mechanical properties.

Capsules↗
PubMedDate not supplied

An operational model for patient-centered informatics.

There are no multidisciplinary operational models to guide nursing informaticists and clinical system users in the design and implementation of computer-supported multidisciplinary care. The Patient-Centered Informatics Model is offered as just such a pragmatic guide. It fuses earlier work with new concepts and allows a visual depiction of crucial elements-influencing factors such as regulations and healthcare delivery models, system attributes such as healthcare delivery methods, knowledge base and supporting technology and categories of results of application processing. The model can help users and executives organize their thinking about the design, implementation, and evaluation of clinical systems in complex settings.

Computer Simulation↗