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Biomedical subjects

C A Ryan

Publications and source records attributed to C A Ryan.

At least 73 records · Page 4Linked to original sources
PubMed1999

Identification of metal allergens in the local lymph node assay.

BACKGROUND: The murine local lymph node assay (LLNA) has recently been endorsed as a validated alternative to guinea pig methods for the identification of skin sensitization hazard. Nevertheless, there has been some debate regarding the utility of this method for the detection of metal contact allergens. OBJECTIVE: In these investigations, we have used the LLNA to determine the skin sensitization potential of 13 metal salts, 8 of which were considered to possess a significant ability to sensitize man, whereas the remaining 5 were judged to lack such potential. RESULTS: The predictions from the LLNA were correct for 7 of the 8 (88%) sensitizing metals and for 4 of the 5 (80%) nonsensitizers when considered against the experience of these metals as human skin sensitizers. Thus, the overall predictive accuracy of the LLNA in relation to metals was 11/13 (85%), which is very similar to the accuracy of approximately 88% in relation to a much larger number of low-molecular-weight organic chemicals, as reported previously. CONCLUSION: These data provide support for the potential utility of the LLNA in hazard identification of metal contact allergens.

Allergens↗
PubMed1999

Care during menopause: comparison of a women's health practice and traditional care.

Despite the growth in primary care-based women's health centers, little is known about the characteristics of women's health patients and the quality of care provided in women's health centers versus traditional practices. Our objective was to compare a women's health practice and a general internal medicine practice on issues of care during menopause. A cross-sectional survey was administered simultaneously to patients aged 50-70 and their primary care physicians in a women's health practice and an affiliated general internal medicine practice. The survey asked patients about health behaviors, past and current hormone use, menopausal symptoms, and attitudes about menopause. Physicians were asked to estimate their patients' attitudes. Patients in women's health practices were younger, more likely to be smokers, and more likely to have had a prior hysterectomy. Women's health patients were somewhat more likely to report concerns related to menopausal symptoms. Women's health patients and patients attending the general internal medicine practice reported similar rates of past or current use of hormone therapy, after adjusting for prior hysterectomy and age. Physicians in women's health and general medicine were similar in their ability to estimate their patients' attitudes. In the general internal medicine practice, female physicians tended to better estimate their patients' attitudes than their male colleagues. Patients seeking care in a women's health practice differed in symptoms and concerns about the menopause compared with patients in a traditional primary care setting. Physicians' understanding of patients' menopausal concerns did not differ between the two practices. However, there may be gender differences in physicians' understanding of patients' concerns.

Attitude to Health↗
PubMed1999

Suppressors of systemin signaling identify genes in the tomato wound response pathway.

In tomato plants, systemic induction of defense genes in response to herbivory or mechanical wounding is regulated by an 18-amino-acid peptide signal called systemin. Transgenic plants that overexpress prosystemin, the systemin precursor, from a 35S::prosystemin (35S::prosys) transgene exhibit constitutive expression of wound-inducible defense proteins including proteinase inhibitors and polyphenol oxidase. To study further the role of (pro)systemin in the wound response pathway, we isolated and characterized mutations that suppress 35S::prosys-mediated phenotypes. Ten recessive, extragenic suppressors were identified. Two of these define new alleles of def-1, a previously identified mutation that blocks both wound- and systemin-induced gene expression and renders plants susceptible to herbivory. The remaining mutants defined four loci designated Spr-1, Spr-2, Spr-3, and Spr-4 (for Suppressed in 35S::prosystemin-mediated responses). spr-3 and spr-4 mutants were not significantly affected in their response to either systemin or mechanical wounding. In contrast, spr-1 and spr-2 plants lacked systemic wound responses and were insensitive to systemin. These results confirm the function of (pro)systemin in the transduction of systemic wound signals and further establish that wounding, systemin, and 35S::prosys induce defensive gene expression through a common signaling pathway defined by at least three genes (Def-1, Spr-1, and Spr-2).

Catechol Oxidase↗
PubMed1999

The effect of a structured neonatal resuscitation program on delivery room practices.

PURPOSE: This study evaluated the introduction of the Neonatal Resuscitation Program (NRP) of the American Academy of Pediatrics and the American Heart Association into the delivery room of an Irish maternity hospital. DESIGN: Prospective, controlled observational study of 51 deliveries before and 51 deliveries following the training of delivery room personnel in the NRP. SAMPLE: Participants were 33 nurse-midwives and 11 pediatric resident physicians. MAIN OUTCOME VARIABLE: Evaluation of postdelivery, newborn resuscitation practices. RESULTS: The introduction of the NRP was associated with significant improvements in delivery room preparation, in the evaluation and management of the newborn infant, and in thermal protection at birth. Although there was a trend to use more free-flow oxygen following the introduction of the NRP, this was not statistically significant. Bag and mask ventilation was also used more frequently following NRP training. However, there were no significant differences in the use of endotracheal intubation, chest compressions, and medications. Fifteen of the 51 infants became hypothermic prior to the introduction of the NRP; none of the infants developed hypothermia in the post-NRP part of the study.

Cardiopulmonary Resuscitation↗
PubMed1999

Cytokine mRNA expression in human epidermis after patch treatment with rhus and sodium lauryl sulfate.

BACKGROUND: Cytokines have been shown to play a pivotal role in the development and elicitation of contact hypersensitivity reactions. The sources of these cytokines in the skin include T cells, keratinocytes, and Langerhans cells. OBJECTIVE: In an effort to characterize the cytokines involved in the elicitation phase of a contact allergic response, we examined mRNA expression in human epidermis following patch testing with a known allergen and vehicle. METHODS: Allergic subjects were patch tested with poison ivy allergen (rhus), irritant (sodium lauryl sulfate [SLS]) and vehicle controls for 24 hours. Epidermal samples were obtained from the patch sites by a suction blister technique. Total RNA was isolated from the epidermis and the level of cytokine gene expression was determined using reverse transcriptase polymerase chain reaction (RT-PCR). PCR products for the various cytokines were confirmed and semiquantitated by liquid hybridization with (32)P-labeled product-specific probes. RESULTS: Results of liquid hybridization confirmed the presence of message for interleukin (IL)-2, IL-4 and IL-10 in rhus, SLS, and vehicle treated sites. Generally, in rhus treated sites, the steady state level of message for IL-2 was highest, followed by IL-4 and IL-10, in decreasing levels. In contrast, only minimal expression of mRNA for these cytokines was observed in irritant and vehicle treated sites. Interestingly, interferon (IFN)-gamma mRNA was not detected at 24 hours in rhus, SLS, or vehicle treated sites. CONCLUSION: These preliminary results indicate differences in the steady state levels of cytokine mRNA in allergen versus vehicle and irritant treated sites at 24 hours after treatment.

Cytokines↗
PubMed1998

delta-Tonoplast intrinsic protein defines unique plant vacuole functions.

Plant cell vacuoles may have either storage or degradative functions. Vegetative storage proteins (VSPs) are synthesized in response to wounding and to developmental switches that affect carbon and nitrogen sinks. Here we show that VSPs are stored in a unique type of vacuole that is derived from degradative central vacuoles coincident with insertion of a new tonoplast intrinsic protein (TIP), delta-TIP, into their membranes. This finding demonstrates a tight coupling between the presence of delta-TIP and acquisition of a specialized storage function and indicates that TIP isoforms may determine vacuole identity.

Amino Acid Sequence↗
PubMed1998

Migration, ethnicity and environment: HIV risk factors for women on the sugar cane plantations of the Dominican Republic.

OBJECTIVE: To determine risk factors for HIV infection among women living in the sugar cane plantation communities (bateyes) of a large private sugar cane company in the Dominican Republic. DESIGN: Cross-sectional study of sexually active female volunteers living in the bateyes. METHODS: Of 98 bateyes, 23 were randomly selected and visited by a mobile medical unit, to interview, examine and test volunteers for seroreactivity to HIV and syphilis. RESULTS: The 490 subjects ranged in age from 16 to 72 years (median, 37 years); 53% were born in Haiti, 36% in Dominican Republic bateyes, and 12% elsewhere in the Dominican Republic; 58% had no formal education; and 87% had no income. HIV seropositivity was found in 28 women (5.7%), including 8.8% of those aged < 35 years. By logistic regression analysis, HIV infection was independently associated with age < 35 years [odds ratio (OR), 4.5; P < 0.01), being single with children (OR, 4.3; P < 0.01), more than one lifetime sex partners (OR, 3.4; P = 0.06), engaging in sex during menses (OR, 3.2; P = 0.02), and self-description as a prostitute (OR, 4.4; P = 0.05)1. For Haitian women, those coming to the Dominican Republic alone were more likely to have HIV infection than those coming with a male partner. Less than 4% of women reported condom use at last intercourse. CONCLUSIONS: Women in the bateyes have a much higher rate of HIV infection than that estimated for women in the general population of Dominican Republic and a rate comparable to that of female sex workers in the Dominican Republic. AIDS prevention in the bateyes should address condom education and distribution as well as employment opportunities and education for women.

Adolescent↗
PubMed1998

Assessment of the skin sensitization potential of topical medicaments using the local lymph node assay: an interlaboratory evaluation.

The murine local lymph node assay (LLNA) is a method for the predictive identification of chemicals that have a potential to cause skin sensitization. Activity is measured as a function of lymph node cell (LNC) proliferative responses stimulated by topical application of test chemicals. Those chemicals that induce a threefold or greater increase in LNC proliferation compared with concurrent vehicle controls are classified as skin sensitizers. In the present investigations we have evaluated further the reliability and accuracy of the LLNA. In the context of an international interlaboratory trial the sensitization potentials of six materials with a history of use in topical medicaments have been evaluated: benzoyl peroxide, hydroquinone, penicillin G, streptomycin sulfate, ethylenediamine dihydrochloride, and methyl salicylate. Each chemical was analyzed in the LLNA by all five laboratories. Either the standard LLNA protocol or minor modifications of it were used. Benzoyl peroxide and hydroquinone, both human contact allergens, elicited strong LLNA responses in each laboratory. Penicillin G, another material shown previously to cause allergic contact dermatitis in humans, was also positive in all laboratories. Streptomycin sulfate induced equivocal responses, in that this material provoked a positive LLNA response in only one of the five laboratories, and then only at the highest concentration tested. Ethylenediamine dihydrochloride dissolved in a 3:1 mixture of acetone with water, or in 4:1 acetone:olive oil (one laboratory), was uniformly negative. However, limited further testing with the free base of ethylene diamine yielded a positive LLNA response when applied in acetone:olive oil (AOO). Finally, methyl salicylate, a nonsensitizing skin irritant, was negative at all test concentrations in each laboratory. Collectively these data serve to confirm that the local lymph node assay is sufficiently robust to yield equivalent results when performed independently in separate laboratories and indicate also that the LLNA is of value in assessing the skin sensitization potential of topical medicaments.

Administration, Topical↗
PubMed1998

Inducible interleukin 4 (IL-4) production and mRNA expression following exposure of mice to chemical allergens.

Previous investigations have indicated that different classes of chemical allergen provoke discrete immune responses in mice characterized by the development of selective cytokine secretion patterns by draining lymph node cells. It was found that, in mice exposed chronically to chemical respiratory allergens, lymph node cells produced high levels of mitogen-inducible interleukin 4 (IL-4), a cytokine necessary for the development of IgE antibody responses. In contrast, exposure of mice to contact allergens resulted in only low levels of IL-4 production. The studies described here were conducted to determine whether differentially induced expression of IL-4 messenger RNA was independent of the need for mitogen stimulation, unlike secretion of IL-4 protein. Mice were exposed to concentrations of trimellitic anhydride (TMA), a respiratory allergen, or to 2,4-dinitrochlorobenzene (DNCB), a contact allergen, under conditions of equivalent immunogenicity and where the former, but not the latter, resulted in significant production of mitogen-inducible IL-4 protein. The steady state levels of IL-4 mRNA in draining lymph nodes were measured by reverse transcription-polymerase chain reaction after a single or repeated daily application of the test chemical to the ears of chronically sensitized mice. Expression of mRNA for IL-4 was evaluated relative to the expression of a housekeeping gene, glyceraldehyde 3-phosphate dehydrogenase. Both chemicals elicited increased steady state levels of IL-4 mRNA by draining lymph node cells compared with vehicle-treated and naive controls. However, using two different treatment protocols, a chronic and an abbreviated chronic protocol and at all times examined, the elevation in IL-4 mRNA steady state levels induced by TMA was greater than that observed with DNCB. These data provide further support for the differential stimulation by contact and respiratory chemical allergens of cytokine secretion patterns in mice and demonstrate that the divergent production of IL-4 in response to these classes of allergen is at least partly transcriptionally regulated.

Allergens↗
PubMed1998

Prosystemin from potato, black nightshade, and bell pepper: primary structure and biological activity of predicted systemin polypeptides.

Prosystemin is the precursor protein of the 18 amino acid wound signal systemin which activates systemic defense in tomato leaves against insect herbivores (McGurl B, Pearce G, Orozco-Cardenas M, Ryan CA, Science 255 (1992) 1570-1573). Here, we report the isolation of cDNA sequences encoding prosystemin from potato (Solanum tuberosum), black nightshade (S. nigrum), and bell pepper (Capsicum annuum), all members of the Solanaceae family, using reverse-transcription polymerase chain reaction (RT-PCR). Pairwise comparisons of the predicted prosystemin proteins from the three species with tomato prosystemin and among each other indicated sequence identities ranging from 73% to 88%. The deduced systemin polypeptides were synthesized and tested for their capacities to induce the synthesis of the defensive proteinase inhibitors in tomato leaves. Potato and pepper systemins were approximately as active as tomato systemin, whereas nightshade systemin was ten-fold less active. The accumulation of proteinase inhibitor mRNA transcripts could be induced in each of these plants by treatment with the homologous systemin. As in the tomato, in potato, black nightshade, and bell pepper plants, prosystemin homologs appear to function as precursors of systemic wound signals.

Amino Acid Sequence↗