Biomedical subjects

Kathleen Harris

Publications and source records attributed to Kathleen Harris.

4 recordsLinked to original sources

PubMed2005

Myosin-binding protein C phosphorylation, myofibril structure, and contractile function during low-flow ischemia.

BACKGROUND: Contractile dysfunction develops in the chronically instrumented canine myocardium after bouts of low-flow ischemia and persists after reperfusion. The objective of this study is to identify whether changes in the phosphorylation state of myosin-binding protein C (MyBP-C) are a potential cause of dysfunction. METHODS AND RESULTS: During low-flow ischemia, MyBP-C is dephosphorylated, and the number of actomyosin cross-bridges in the central core of the sarcomere decreases as thick filaments dissemble from the periphery of the myofibril. During reperfusion, MyBP-C remains dephosphorylated, and its degradation is accelerated. CONCLUSIONS: Dephosphorylation of MyBP-C may initiate changes in myofibril thick filament structure that decrease the interaction of myosin heads with actin thin filaments. Limiting the formation of actomyosin cross-bridges may contribute to the contractile dysfunction that is apparent after low-flow ischemia. Breakdown of MyBP-C during reperfusion may prolong myocardial stunning.

Actins↗

PubMed2005

Metoclopramide effect on breastfeeding the preterm infant: a randomized trial.

OBJECTIVE: To investigate the effect of metoclopramide on breast milk volume and duration of breastfeeding in women delivering preterm. METHODS: Women who planned to breastfeed and delivered between 23 and 34 weeks of gestation were eligible to participate in this randomized, double-blind, placebo-controlled study. Women were randomized to receive 10 mg of metoclopramide or placebo 3 times a day for 10 days, starting within 96 hours of birth. Breastfeeding education was standardized for all women. Mothers recorded the volume of breast milk expressed at each pumping for 17 days. Duration of breastfeeding was measured by monthly follow-up phone calls to each subject. RESULTS: Sixty-nine women were enrolled and 57 (82%) women completed the study: 28 in the metoclopramide group and 29 in the placebo group. The 2 groups were similar in age, education, ethnicity, gestational age, and marital status. There was no significant difference between breast milk volumes in the metoclopramide and placebo groups at each of the 17 days of the study (P = .26 to .98; test for mean metoclopramide effect P = .80). There was no significant difference between groups in duration of breastfeeding, with a median of 8.8 weeks, an interquartile range of 3.4 to 12.0 weeks for the metoclopramide group and a median of 8.6 weeks, and an interquartile range of 5.6 to 16.9 weeks for the placebo group (P = .09). CONCLUSION: Metoclopramide did not improve breast milk volume or duration of breastfeeding in this population of women. Regardless of therapy received, breastfeeding duration in this study of preterm mothers was poor. LEVEL OF EVIDENCE: I.

Adult↗

PubMed2002

Lidocaine iontophoresis versus eutectic mixture of local anesthetics (EMLA) for IV placement in children.

UNLABELLED: Pain during venipuncture is a major source of concern to children and their caretakers. Iontophoresis is a novel technique that uses an electrical current to facilitate movement of solute ions (lidocaine) across the stratum corneum barrier to provide dermal analgesia. In this study, we compared dermal analgesia provided by lidocaine iontophoresis and eutectic mixture of local anesthetics (EMLA). After informed consent, 26 children, aged 7-16 yr, who required venous cannulation on multiple occasions, were enrolled in this prospective, randomized, crossover study to receive EMLA and iontophoresis on separate occasions. During a third session, each subject received his or her preferred treatment. Pain during venipuncture was assessed by the subject, parent, observer, and technician performing the procedure, by use of a 100-mm visual analog scale. The observer also used the Children's Hospital of Eastern Ontario Pain Scale to rate the subject's pain. Ratings of subject satisfaction were also assessed. There were no significant differences between the two groups in the subject-rated visual analog scale or the Children's Hospital of Eastern Ontario Pain Scale scores. Eleven (50%; 95% confidence interval [CI], 31%-69%) of the 22 subjects who completed both sessions preferred iontophoresis. Five subjects (23%; 95% CI, 10%-44%), including two who did not tolerate treatment with iontophoresis, preferred EMLA, and six (27%; 95% CI, 13%-48%) had no preference for the intervention to provide dermal analgesia. We conclude that lidocaine iontophoresis provides similar pain relief for insertion of IV catheters as EMLA and is a useful noninvasive alternative to establish dermal analgesia for venous cannulation. IMPLICATIONS: Iontophoresis is a technique that uses an electrical current to facilitate movement of solute ions (lidocaine) across the stratum corneum barrier to provide dermal analgesia. Lidocaine iontophoresis provides similar pain relief for insertion of IV catheters as eutectic mixture of local anesthetics and is a useful noninvasive alternative to establish dermal analgesia for venous cannulation.

Administration, Topical↗

PubMedDate not supplied

Superantigens and chronic rhinosinusitis: skewing of T-cell receptor V beta-distributions in polyp-derived CD4+ and CD8+ T cells.

BACKGROUND: Recent studies have suggested that Staphylococcus aureus secrete superantigenic toxins that play a role in the etiology of chronic rhinosinusitis with nasal polyposis (CRSwNP). Twenty S. aureus superantigens (SAg's) have been identified, each of which bind the V beta-region of the T-cell receptor (TCR) outside the peptide-binding site. Approximately 50 distinct V beta-domains exist in the human repertoire, and distinct SAg's will bind only particular domains generating a pattern of V beta-enrichment in lymphocytes dependent on the binding characteristics of a given toxin. The aim of this study was to analyze the pattern of V beta-expression in polyp-derived lymphocytes from CRSwNP patients. METHODS: Polyps were harvested from 20 patients with CRSwNP and 3 patients with antrochoanal polyps. Flow cytometry was used to analyze the V beta-repertoire of polyp-derived CD4+ and CD8+ lymphocytes. Data were analyzed in light of the known skewing associated with SAg exposure in vivo and in vitro. Skewing was defined as a percentage of V beta-expression >2 SD of that seen in normal blood. RESULTS: Seven of 20 subjects exhibited skewing in V beta-domains with strong associations with S. aureus SAg's. The three antrochoanal polyps failed to show any significant V beta-skewing. CONCLUSION: This study establishes evidence of S. aureus SAg-T-cell interactions in polyp lymphocytes of 35% of CRSwNP patients. Although these results are consistent with intranasal exposure of polyp lymphocytes to SAg's, additional study is necessary to establish the role of these toxins in disease pathogenesis.

CD4-Positive T-Lymphocytes↗