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Biomedical subjects

C Johnson

Publications and source records attributed to C Johnson.

At least 325 records · Page 18Linked to original sources
PubMed1991

Agonist-induced fluctuations in cytoplasmic calcium in primary cultures of bovine endothelial cells.

Endothelial cells play an important role in the vascular responsiveness to many stimuli by releasing locally active agents. The intracellular signal which links the external stimulus to the release of the active compounds is almost certainly an elevation in cytoplasmic calcium (Cai2+). Thus a detailed knowledge of Cai2+ regulation is central to an understanding of the physiology and pharmacology of endothelial cells. The present experiments, on single bovine aortic endothelial cells, demonstrate that agonists stimulate complex changes in Cai2+. These include rapid and regular fluctuations in Cai2+ which are different from the oscillations reported in other endothelial cells and non-excitable cells. The fluctuations are completely abolished in media containing low calcium, 2 mM-cobalt or caffeine but are not affected if the cells are bathed in isotonic potassium solutions. The hypothesis is put forward that the fluctuations in Cai2+ are associated with localized influxes of calcium and are possibly involved with the recycling of calcium between the internal stores, the cytoplasm and the external medium.

Adenosine Triphosphate↗
PubMed1991

Single-dose and three-day regimens of ofloxacin versus trimethoprim-sulfamethoxazole for acute cystitis in women.

We compared the safety and efficacy of a single 400-mg dose of ofloxacin, ofloxacin (200 mg) once daily for 3 days, and trimethoprim-sulfamethoxazole (160:800 mg) twice daily for 7 days for the treatment of acute uncomplicated cystitis (urinary tract infection [UTI]) in women. At 5 weeks posttreatment, 35 (81%) of 43 patients treated with single-dose ofloxacin, 40 (89%) of 45 treated with 3 days of ofloxacin, and 41 (98%) of 42 treated with trimethoprim-sulfamethoxazole were cured (P = 0.03, single-dose ofloxacin group versus trimethoprim-sulfamethoxazole group). Retreatment for symptomatic recurrent UTI was given to 7 (16%) of 43 patients initially treated with single-dose ofloxacin, 3 (7%) of 45 patients treated with 3 days of ofloxacin, and 0 of 42 patients treated with trimethoprim-sulfamethoxazole (P = 0.01, single-dose ofloxacin group versus trimethoprim-sulfamethoxazole group). There was a trend in each of the three treatment groups toward an association between persistent or recurrent episodes of significant bacteriuria and a history of UTI in the past year and with diaphragm use. Ofloxacin was more effective than trimethoprim-sulfamethoxazole in eradicating Escherichia coli from rectal cultures during or soon after therapy, but there were no differences at later follow-up visits. Adverse effects were equally common among the three treatment groups. We conclude that single-dose ofloxacin was less effective than 7 days of trimethoprim-sulfamethoxazole for treatment of uncomplicated cystitis in women, while the 3-day ofloxacin regimen and the trimethoprim-sulfamethoxazole regimen were not significantly different in efficacy.

Acute Disease↗
PubMed1991

Use of a monoclonal antibody enzyme-linked immunosorbent assay to measure human respiratory glycoprotein production in vitro.

High-molecular-weight glycoprotein from human airway cultures was used to generate murine monoclonal antibodies, one of which recognizes a high-molecular-weight, hyaluronidase-resistant glycoprotein localized by immunofluorescent microscopy and immunogold electron microscopy to the secretory granules of human airway submucosal gland mucous cells and goblet cells. This monoclonal antibody was used to develop an enzyme-linked immunosorbent assay (ELISA) that was adapted to the study of respiratory glycoprotein secretion from human airways in vitro. Using the assay, the effect of a known mucus secretagogue, the cholinergic agonist methacholine, was studied on explant cultures of tissue from human bronchus or from human nasal mucosa. In studies of human bronchus explants, methacholine, 100 and 10 microM, stimulated increased secretion of respiratory glycoprotein (RGP) by 109 +/- 8% (n = 14; P less than 0.001) and 96 +/- 14% (n = 9; P less than 0.001), respectively, above control values. In studies of human nasal turbinate mucosal explants, methacholine, 100 and 10 microM, stimulated increased secretion of RGP by 75 +/- 28% (n = 7; P less than 0.01) and 70 +/- 21% (n = 4; P less than 0.01) above control values. An ELISA for the measurement of RGP secretion may provide a sensitive and more specific method for the performance of in vitro studies of RGP secretion from human tissues.

Animals↗
PubMed1991

The black and deaf movements in America since 1960. Parallelism and an agenda for the future.

This paper traces the political and educational movements of both black and hearing-impaired Americans since 1960 and compares their common as well as disparate but equally significant experiences. The purpose of the comparisons is to identify problems and proven solutions that collectively suggest a strategy for the continuing movement of hearing-impaired people. The authors, through their ethnicity--three are black and two are white--and personal and professional experiences bring divergent but relevant points of view to the question of multicultural coalitions and their abilities to effect social change. Four principles or suggestions for advancing the agenda of hearing-impaired Americans are presented: (1) the need to define the issues that will continue to confront hearing-impaired Americans through the year 2000, (2) the need to enlarge the membership and participation of existing coalitions, (3) the need to address local, vocational, technical, and educational issues, and (4) the need to facilitate hearing-impaired networking groups within religious, social, business, and cultural organizations.

Black or African American↗
PubMed1991

Serum total cholesterol: HDL cholesterol ratios in US white and black adults by selected demographic and socioeconomic variables (HANES II).

BACKGROUND: Framingham Study findings suggest that total cholesterol (TC):High density lipoprotein cholesterol (HDL-C) ratio is a useful summary of the joint contribution of TC and HDL-C to coronary heart disease (CHD) risk. Information on the distribution of TC:HDL-C in the US population is limited to selected populations and the relationship of the ratio distribution and its correlates has received little attention. METHOD: TC/HDL-C ratios were examined in a representative sample of the United States adult population ages 20 to 74 years, between February 1976 and February 1980 during NHANES II, using stratification and multivariate regression analyses. RESULTS: Age-adjusted mean ratios were higher in men compared with women and were higher in Whites compared with Blacks. White men had the highest TC/HDL-C mean ratios. These relationships remained after stratification by age, education, body mass index, alcohol use, cigarette smoking, and physical activity. Using multivariate analyses, the ratios were positively related to BMI, age, and smoking; and negatively related to female sex, alcohol use, being Black, and physical activity. CONCLUSIONS: Using a ratio reference point of greater than or equal to 4.5 from the Framingham study, at least an estimated 44 million persons ages 25 to 74 years in the US were found to be at higher risk of developing coronary heart disease.

Adult↗
PubMed1991

Fine needle aspiration diagnosis of hyperplastic and neoplastic follicular nodules of the thyroid. A morphometric study.

The differentiation of hyperplastic nodules, follicular adenomas and follicular carcinomas from fine needle aspiration (FNA) cytology smears may be difficult. To better define the diagnostic criteria, we studied the morphometric parameters of nuclear area (NA), nuclear:cytoplasmic ratio and nuclear roundness (NR) in single cells and cell aggregates. In addition, we quantitated the percentage of touching or overlapping nuclei (NO) and the percentage of extent of nuclear area of overlap (NAO) in cellular aggregates. We measured cellular samples from FNA aspirates obtained from 20 hyperplastic nodules, 21 follicular adenomas, 5 encapsulated follicular carcinomas and 22 invasive follicular carcinomas, all of which were subsequently confirmed by histologic examination. Cellular aggregates provided the maximum diagnostic information. Stepwise discriminant analysis revealed that nuclear size, nuclear roundness and the percentage NAO allow optimum differentiation of hyperplasia, adenomas and carcinomas. Clearly, all of the poorly differentiated carcinomas (large NA, low NR, high NO and NAO) could be reliably diagnosed. Discriminant analysis allowed the differentiation of carcinoma from adenoma in 20/22 carcinomas (91%) and all 21 adenomas (although 2 adenomas were called hyperplasias and 3 hyperplasias were called adenomas).

Adenoma↗
PubMed1991

Molecular definition of the shortest region of deletion overlap in the Langer-Giedion syndrome.

The Langer-Giedion syndrome (LGS), which is characterized by craniofacial dysmorphism and skeletal abnormalities, is caused by a genetic defect in 8q24.1. We have used 13 anonymous DNA markers from an 8q24.1-specific microdissection library, as well as c-myc and thyroglobulin gene probes, to map the deletion breakpoints in 16 patients with LGS. Twelve patients had a cytogenetically visible deletion, two patients had an apparently balanced translocation, and two patients had an apparently normal karyotype. In all cases except one translocation patient, loss of genetic material was detected. The DNA markers fall into 10 deletion intervals. Clone L48 (D8S51) defines the shortest region of deletion overlap (SRO), which is estimated to be less than 2 Mbp. Three clones--p17-2.3 EE (D8S43), L24 (D8S45), and L40 (D8S49) - which flank the SRO recognize evolutionarily conserved sequences.

Bacteriophage lambda↗
PubMed1991

Dose-dependent thermal response of tumor pH and energy metabolism evaluated by in vivo 31P NMR spectroscopy and microelectrodes.

In vivo 31P NMR spectroscopy and pH microelectrodes were employed to measure the energy metabolism and pH of a mammary carcinoma in the flank of the C3H mouse before and serially up to a week after various hyperthermia treatments. Water bath hyperthermia was used to treat the tumor at 43.5 degrees C for 30 min (TCD0/30, NMR measurement only), 1 h (TCD10/30), and 2 h (TCD60/30), respectively. The data indicate that, except at 4 h after TCD60/30 treatment, all pH values measured by NMR (pHn) were significantly higher (P less than or equal to 0.001) compared to pH values measured by microelectrodes (pHe) at all treatment levels and times. The magnitude of the difference between pHn and pHe (delta pH) was significantly decreased from the pretreatment level only at 4 h after hyperthermia treatment (0.51 pH units for TCD60/30 and 0.21 pH units for TCD10/30). The ratio of beta-nucleoside triphosphate to inorganic phosphate (beta-NTP/Pi) and pHn were more sensitive to hyperthermia treatment than pHe. The beta-NTP/Pi ratio failed to recover to the pretreatment ratio after 1 or 2 h hyperthermia treatment, while a total recovery was observed within 72 h for 30 min hyperthermia treatment. Our data suggest that the temporal profile of beta-NTP/Pi, pHn, and delta pH may be indicative of the biological outcome of hyperthermia treatment.

Animals↗
PubMed1991

Promoting bicycle helmets: a new focus for injury prevention.

Bicycle accidents cause many serious injuries and deaths in the United States, often as a result of head injury in riders not wearing helmets. Helmets reduce the incidence of head injury, and an aggressive safety education campaign has been shown to increase the number of children wearing helmets while riding. Such a campaign has been initiated in the Central Indiana area. The campaign is designed to educate families and to promote bicycle helmet use among children and their parents. Suggestions are given on how physicians can help educate, distribute information and encourage bicycle helmet use through their contact with families. A resource list is included so these materials can be easily obtained. Ultimately, we hope such a program will increase helmet use and consequently reduce morbidity and mortality from head injury in Indiana's children.

Bicycling↗
PubMed1990

Binding of platelet activating factor to albumin.

Binding of platelet activating factor (1-O-alkyl-2-O-acetyl-sn-glycero-3-phosphocholine) to albumin is an important facet of the biological activity of this phospholipid. Measurement of that binding has been hampered by the physical nature of the lipid, which made estimation of the free and bound concentrations difficult. With the use of ultracentrifugation to generate an albumin gradient and to produce a region free of protein, the successful measurement of free PAF and PAF bound to albumin was accomplished. This study has demonstrated that PAF binds to albumin at four binding sites and that the average equilibrium dissociation constant for this binding is 1.10(-7) M. Consideration of these data has led to the hypothesis that the receptor active form of PAF is the albumin-PAF complex, rather than free PAF.

Humans↗