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Biomedical subjects

B T Smith

Publications and source records attributed to B T Smith.

124 records · Page 7Linked to original sources

Effects of cortisol on serially propogated fibroblast cell cultures derived from the rabbit retal lung and skin.

Cortisol affects the growth of serially propogated, fibroblast cell cultures derived from the rabbit fetal lung in a manner which is dependent upon the gestational age of the material used: early in gestation (20 days), the hormone (10(-7)-10(-5) M) stimulates [6-3H]thymidine incorporation into DNA, while in late gestation (28 days), cortisol (10(-7) and 10(-6) M) inhibits this process. Cultures derived from the rabbit fetal skin are inhibited by cortisol (10(-5) M) at both gestational ages. Fibroblasts derived from lung, but not from skin, efficiently convert cortisone to cortisol and this activity increases with advancing gestation. Cortisol does not affect the incorporation of [3H]choline into lecithin by confluent cultures of any of the fibroblast types studied.

Animals↗

The rabbit fetal lung as a glucocorticoid target tissue.

Fetal lung cells from 28 day gestation rabbits cultured in the presence of cortisol (5.5 times 10 - minus 6M) or dexamethasone (5.5 times 10- minus 8M) incorporated [3-H] choline into lecithin to a significantly greater extent than did control cultures. 11-Deoxycortisol, 21-deoxycortisol and 11beta-hydroxyprogesterone, at a concentration of 5.5 times 10- minus 5 M, had no effect on lecithin synthesis. However, when lung cells were simultaneously exposed to these steroids and to cortisol at the concentrations quoted, [3-H] choline incorporation was reduced to control values. Cortisone (5.5 times 10- minus M) also enhanced lecithin synthesis, the activity of the steroid likely being related to the capacity of the lung cells to convert cortisone to cortisol. This hypothesis was supported by the observations that 11-ketoprogesterone (1.3 times 10- minus 5M), which totally inhibited the conversion of cortisone to cortisol and which had no effect of its own on [3-H] choline incorporation, inhibited the effect of cortisone on lecithin synthesis but not that of cortisol. These data support the view that glucocorticoids affect lung cell maturation in a manner comparable to the interaction of other steroid hormones with their target tissues. The capacity of the fetal lung to convert cortisone to cortisol may be physiologically significant in light of the high concentration of 11-oxo-steroids in the fetal circulation throughout pregnancy.

Aldosterone↗

Evidence for different gestation-dependent effects of cortisol on cultured fetal lung cells.

The effect of cortisol (5.5 muM) on primary monolayer cultures of trypsin-dispersed lung cells from rabbit fetuses of 20-28 days gestation was monitored with respect to (a) cellular growth as determined by DNA content after 72 h, at which time all cultures were in the exponential phase of growth, and (b) cellular maturation as reflected by the incorporation of [(14)C]-palmitate into saturated lecithin and its release into the culture medium. Cortisol significantly increased growth in cultures prepared from 20 day (control: 59.8+/-8.9 nmol DNA/flask; cortisol: 118.7+/-15.7, P < 0.001) and 22 day (control: 69.2+/-17.2; cortisol: 106.7+/-13.3, P < 0.001) fetuses but had no effect on the growth of cells from 24 or 26 day fetuses. At 28 days, the effect was reversed, cortisol reducing growth by a factor of two (control: 42.0+/-8.5; cortisol: 19.3+/-4.0, P < 0.001). Incorporation of palmitate into lecithin was expressed as picomoles incorporated per micromole DNA per flask, thus correcting for differences in the number of cells. Cortisol had no effect on palmitate incorporation until day 26, at which time it caused a slight increase (control: 51.2+/-5.5: cortisol: 72.8+/-16.2, P < 0.01) which became very striking by day 28 (control: 19.7+/-3.1; cortisol; 286.8+/-47.0, P < 0.001). The proportion of recovered radiolabeled lecithin that was disaturated rose with gestational age from 72% at 20 days to 98% at 28 days. Saturated lecithin made up over 90% at the two gestational ages (26 and 28 days) where cortisol increased palmitate incorporation. In contrast, cortisol had no effect on the incorporation of palmitate into sphingomyelin at any of the gestational ages studied.The results suggest that cortisol may increase fetal pulmonary cellular growth in early gestation while enhancing maturation and slowing growth as term approaches.

17-Hydroxycorticosteroids↗

Marcia Crocker Noyes, medical librarian: the shaping of a career.

This study explores the accomplishments of Marcia Crocker Noyes (1869-1946) in depth and examines how her unobtrusive, yet extremely influential, personality contributed to success in medical librarianship. In the library of the state medical society of Maryland and in the Medical Library Association, this pioneer medical librarian acted as a revitalizing force, and thus was in part responsible for the survival and subsequent growth of both institutions. Perhaps as important as her concrete contributions to medical libraries was the legacy which Miss Noyes bequeathed to her colleagues. She not only shaped the vocation of medical librarianship, but also by her example, stressed the dedication to the future necessary for one to be termed a professional.

History, 19th Century↗

Pharmacoeconomic analysis of oral therapies for onychomycosis: a US model.

An evaluation of treatment practices in 13 countries, not including the United States, has shown oral terbinafine to be more cost-effective (from a government payer perspective) than griseofulvin, itraconazole, and ketoconazole in the treatment of onychomycosis of toenails and fingernails. The purpose of this study was to evaluate the clinical and economic effects of oral griseofulvin, itraconazole, ketoconazole, and terbinafine in the treatment of onychomycosis from the perspective of a third-party payer in the United States. A previously constructed decision-analytic model evaluating the costs of onychomycosis in 13 countries outside the United States was updated to determine the costs of treating onychomycosis in the United States. Clinical management patterns were assessed to identify and quantify physician visits, laboratory tests, and adverse drug reaction treatment components for patients with toenail and fingernail onychomycosis. A random-effects model meta-analysis of treatment efficacy (mycologic cure) and New York Metropolitan Medicare charge data for physician fees were used in the treatment model. A sensitivity analysis assessing alternative dosing regimens and a rank order stability analysis investigating the effects of length of treatment, success rates, relapse rates, and drug acquisition costs on overall results were also conducted. Terbinafine had the lowest cost per mycologic cure after one treatment regimen for onychomycosis in both toenail and fingernail infections ($791.00 and $454.00, respectively). The costs of treating toenail and fingernail infections were comparatively higher for therapy with itraconazole ($1535.00 and $767.00, respectively), griseofulvin ($2385.00 and $837.00, respectively), and ketoconazole ($10,025.00 and $1512.00, respectively). As a primary treatment choice, terbinafine also had the lowest overall expected cost per patient for both toenail and fingernail infections ($977.00 and $550.00, respectively). Griseofulvin had expected costs ($1543.00 and $822.00, respectively) similar to itraconazole ($1588.00 and $894.00, respectively), whereas ketoconazole was the most expensive primary treatment choice ($2359.00 and $1287.00, respectively). This study demonstrates that terbinafine is an economical and cost-effective treatment for patients with dermatophytic onychomycosis, supporting European and Canadian studies. Except for the rank order of griseofulvin and itraconazole, sensitivity analyses show that these results are fairly stable.

Administration, Oral↗

Inhibition of lung maturation by monoclonal antibodies against fibroblast-pneumonocyte factor.

Fetal lung maturation, especially the onset of surfactant formation by alveolar type II cells, seems to be regulated by endogenous fetal glucocorticoids. Recent studies suggest that glucocorticoids do not act directly on the type II cell but rather on the lung mesenchyme. In response to glucocorticoids, the mesenchyme produces and secretes a polypeptide, fibroblast-pneumonocyte factor, which in turn stimulates surfactant synthesis by the alveolar type II cell. We report here the generation of hybridomas secreting monoclonal antibodies to rat lung fibroblast-pneumonocyte factor. Two monoclonal antibodies studied in detail reduced the cortisol-stimulated synthesis of saturated phosphatidylcholine in organotypic cultures of fetal rat lung cells and blocked the stimulatory effect of fibroblast-pneumonocyte factor in type II cells from these cultures. When embryonic chicks were injected on day 15 of incubation with either monoclonal antibody, they showed on days 20 and 21 biochemical evidence of delayed lung maturation as compared with controls. These effects were organospecific. Our observations support a physiological role for fibroblast-pneumonocyte factor in prenatal lung maturation.

Animals↗

Outcomes of tendon transfer surgery and occupational therapy in a child with tetraplegia secondary to spinal cord injury.

OBJECTIVE: Tendon transfer surgery to augment hand function lost to spinal cord injury (SCI) has gained acceptance as a rehabilitation option for adults but has yet to be fully explored in children. In this study, hand function and performance of activities of daily living in an 11-year-old child with an SCI were evaluated before and after surgical transfers of the brachioradialis to the flexor pollices longus and the extensor carpi radialis longus to the flexor digitorum profundus. METHOD: With the use of a single-subject AB design, repeated measures of pinch force, the Jebsen Test of Hand Function for Children and the Grasp and Release Test were obtained before tendon transfer surgery and at 2 1/2 6, and 12 months after surgery. Activities of daily living were assessed with the Functional Independence Measure (FIM) and the Common Object Test (COT) before surgery and 12 months after surgery. RESULTS: Each assessment revealed a significant improvement in hand function after surgery. Pinch force was measurable only after tendon transfers and increased throughout the first year. By two standard deviation analyses, after surgery there were significantly more task completions for all Grasp and Release Test objects, and task completion times were shorter for the light and heavy objects of the Jebsen Test of Hand Function for Children. FIM results showed that self-catheterization and cutting food were possible only after surgery, and results of the COT revealed new unilateral and bilateral abilities that facilitated the client's independence in writing, eating, applying toothpaste, and brushing teeth. CONCLUSION: This single-subject study demonstrates the benefits of tendon transfers for active grasp in a child with an SCI.

Activities of Daily Living↗

A prospective evaluation of upper extremity tendon transfers in children with cervical spinal cord injury.

Three children (five hands) between 6 and 11 years of age with cervical level spinal cord injuries underwent tendon transfers to restore voluntary lateral pinch. Repeated measures of pinch force and the Grasp and Release Test (GRT) were obtained before surgery and at regular intervals after tendon transfers. The Functional Independence Measure (FIM) was administered before surgery and at 12 months after surgery. Responses to open-ended questions were used to supplement the FIM data at 1 year after surgery. Before surgery, no measurable force was obtained in any hand; after tendon transfers, pinch and finger flexion forces increased throughout the follow-up period. On the GRT, manipulation of the heavy objects was possible only after tendon transfers. Improvements were realized in feeding, grooming, bladder management, play, and school tasks. Each child requested surgery to restore pinch in the nondominant hand. Two hands required tenolysis procedures. Despite capsulotomies and aggressive therapy, three hands continued to have range limitations at the metacarpophalangeal joints.

Activities of Daily Living↗

Paracrine regulation of lung maturation.

Although there is much yet to be learned about the regulation of fetal lung maturation, the study of this process has yielded much information that may serve as a paradigm for the understanding of fetal growth regulation in general. Two particularly interesting fetal adjustments of general regulatory phenomena have emerged: the ability of local tissue metabolism to anatomically or temporally isolate endocrine effects and the role of paracrine factors in coordinating the responses of different cells in complex organs.

Animals↗