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Biomedical subjects

C S Johnson

Publications and source records attributed to C S Johnson.

159 records · Page 9Linked to original sources
PubMed1974

Pregelation aggregation of sickle cell hemoglobin.

Quasi-elastic light scattering was used to detect the initial stage of aggregation of hemoglobin S solutions. Aggregation of a hemolysate upon deoxygenation was found to occur at concentrations above 11 g/dl, but purified hemoglobin S solutions showed evidence of aggregation only for concentrations greater than 14 g/dl. A transition from a nonaggregated to an aggregated state was observed when the oxygen pressure in solution was reduced below a critical value. The total intensity of the scattered light during the early stages of aggregation was found to increase linearly with time. This result is consistent with a linear association process in which any size aggregate can combine with any other size aggregate.

Adult↗
PubMedDate not supplied

Tracheoesophageal speech: predictors of success and social validity ratings.

PURPOSE: The purpose of this study was to examine long-term success rates and predictors of success for patients who had undergone either primary or secondary tracheoesophageal puncture. An additional aim was to compare judgments of communication effectiveness made by a speech-language pathologist with those made by the patient or significant other. PATIENTS AND METHODS: Thirty-six laryngectomees were initially rated on a 5-point functional communication scale. These ratings resulted in the formation of two distinct groups that were identified as "successful" and "unsuccessful." The groups were compared on the basis of age at time of surgery and 10 categorical variables that have been implicated in the success or failure of tracheoesophageal puncture surgery. RESULTS: Results indicated that nearly two thirds of the patients had successful communication at an average of approximately 4 years posttracheoesophageal puncture. For the 13 patients judged as "unsuccessful," reduced vision, limited arm/hand movement, and history of radiotherapy were found in significantly greater numbers. When communication profile ratings made by a speech-language pathologist were compared with those made by the patient or significant other (P/SO), approximately one-third varied by at least "1" scale value, with the vast majority resulting in comparatively higher ratings by the speech-language pathologist. CONCLUSION: The findings of this study are in general agreement with previously published success rates for tracheoesophageal puncture and attest to the long-term nature of these success rates in a majority of patients. Additional investigation is necessary to identify factors that may contribute to discrepancies between clinician expectations and those of the patient or significant other.

Female↗
PubMedDate not supplied

Age and growth factors in porcine full-thickness wound healing.

It has been recognized that the rate of cutaneous wound healing declines with age, yet the molecular processes that affect this decline remain poorly understood. The purpose of this study was to compare reepithelialization and contraction rates, and growth factor profiles in full-thickness wounds in swine of various ages. Multiple full-thickness excisional wounds were created on the dorsum of 24-month-old (n=2), 4-month-old (n=2), and 2-month-old (n=2) Yucatan Minipigs. The extent of reepithelialization was shown to decrease with increasing age in a manner that was statistically significant among the 2-month-old (79%), 4-month-old (48%), and 24-month-old pigs (22%). Enzyme-linked immunosorbent assay results showed that endogenous vascular endothelial growth factor concentrations in the 2- and 4-month-old animals peaked on day 4, reaching levels of 482 pg/ml and 420 pg/ml, respectively. In the 24-month-old pigs the vascular endothelial growth factor concentration peaked later (day 6), and was present at a lower level (229 pg/ml). On day 4 the vascular endothelial growth factor levels in the older pigs reached only 120 pg/ml, representing a four-fold decrease in concentration compared to the younger pigs. A comparison of platelet-derived growth factor-BB concentrations across the age groups showed similar patterns in the 2- and 4-month-old pigs (peaks of 77 and 91 pg/ml on days 2 and 3, respectively), and levels in the 24-month-old were below the sensitivity level (31.5 pg/ml) of the assay. Transforming growth factor-beta1 levels across the age groups did not differ in a manner that was statistically significant, and all age groups peaked on day 9. Wound contraction showed no statistical differences among the age groups from days 3 to 9. On day 11, however, wound contraction in 2-month-old pigs was about 10% faster than in 24-month-old pigs (p < 0.05). These data suggest a possible new algorithm for treating wounds in aged skin, by which exogenous growth factors can be added to the wound microenvironment in doses and at times that match the growth factor profiles observed in wounds made in younger skin.

Age Factors↗
PubMedDate not supplied

Effects of an oral contraceptive combination with or without androgen on mammary tissues: a study in rats.

OBJECTIVES: Oral contraceptive (OC) therapy has long been known to produce hypoandrogenemia. However, androgens are not part of any OC therapy available to women. This project was designed to evaluate the effects of low-estradiol containing OC, with or without methyltestosterone (MT), on cell proliferation and progesterone receptor (PgR) expression in mammary gland epithelia of virgin female rats. METHODS: Sixty rats were divided into four groups. One group received OCs, whereas a second group received OC plus MT. A third group of rats was treated with an antiandrogen to mimic the hypoandrogenemic effects caused by OC therapy. All treated groups were compared with age-matched untreated controls. RESULTS: After 15 weeks of treatment, no inflammatory, precancerous, or cancerous lesions were observed in any treatment group. OC plus MT therapy caused significant suppression of epithelial proliferation, a reduction in the number of proliferating cell nuclear antigen-labeled cells, and an increase in the number of PgR-labeled cells. CONCLUSIONS: Our results suggest that a medication containing an estrogen-progestin-androgen combination has antiproliferative effects in mammary glands of experimental animals that could prove to have breast-protective potential in women.

Androgens↗
PubMedDate not supplied

In vivo effects of recombinant human and murine interleukin-1 alpha (IL-1 alpha) on murine hematopoiesis.

Interleukin-1 alpha (IL-1 alpha) has profound effects on hematopoiesis that could be exploited therapeutically. The cytokine potentiates immature myeloid and erythroid progenitor cells and suppresses late-stage erythropoiesis. To evaluate the species specificity of IL-1 alpha's activities, we compared the dose-related in vivo effects of recombinant murine IL-1 alpha (MuIL-1 alpha) with recombinant human IL-1 alpha (HuIL-1 alpha) on mouse hematopoietic precursor cells. Normal mice were treated with a single i.p. injection of either HuIL-1 alpha or MuIL-alpha at various doses and assayed 48 hours later. MuIL-1 alpha induced a significantly greater suppression of mature erythroid progenitors (CFU-E) than an equivalent dose of HuIL-1 alpha. Likewise, the immature erythroid (BFU-E) as well as the mature macrophage (CFU-M) progenitors were stimulated to a significantly greater extent with MuIL-1 alpha than with HuIL-1 alpha. These results demonstrate that isologous system should be utilized to optimally evaluate the in vivo use of IL-1 alpha for potentiating hematopoiesis.

Animals↗
PubMedDate not supplied

Accuracy of Pap smear and mammogram self-reports in a southwestern Native American tribe.

The use of Pap smears and mammograms in the Native American population is not well documented and the validity of women's self-reports is unknown. The purpose of this study was to examine the agreement between women's self-reports of their Pap smear and mammogram histories with their medical records in one Native American tribe. Two hundred fifty-one women between the ages of 35 and 65 answered questions regarding their Pap smear and mammogram histories. These women then underwent an education program and one year later they again answered questions about their Pap smear and mammogram histories. Two hundred four of the original 251 women completed the education program and the second questionnaire. On the first questionnaire, 51.0% of women's claims to have received a Pap smear within the past 12 months were verified by the record audit and 69.2% of claims of receiving a mammogram within the past 12 months were verified. On the second questionnaire, 46.7% of women who said they had received a Pap smear within the past 12 months had their claims verified by their records, and 45.2% of women's claims of receiving a mammogram within the past 12 months were verified. These results suggest that patient recall alone should not be used to determine date of last procedure.

Adult↗