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Biomedical subjects

R Connors

Publications and source records attributed to R Connors.

At least 19 recordsLinked to original sources
PubMed2001

Introduction of corneal astigmatism through placement of a scleral fixation ring in eye bank eyes.

PURPOSE: To determine the effect of scleral fixation ring placement in induction of astigmatism by topographic analysis. METHODS: Baseline measurements were used in human eyes from the Utah Lions Eye Bank. In two control eyes, the effect of placing and replacing the eye in the holder was determined. In nine eyes, the effect of placing a 14-mm ring 2.0-mm from the limbus and an 18-mm ring 4.0-mm from the limbus, both in line with and between the rectus muscles, was determined. Induced astigmatism (IA) was determined by Alpins' vector analysis method. RESULTS: Control eyes had a mean variation of 0.26 +/- 0.18 diopters (D) (range, 0.07-0.65). The study eyes had a mean IA of 1.55 D with statistically significant differences noted when comparing 14-mm rings (0.92 +/- 2.00 D) versus 18-mm rings in line with the rectus (3.02 +/- 1.49 D; p = 0.02), with 18-mm rings in line with the rectus muscles (3.02 +/- 1.46 D) versus between the muscles (1.37 +/- 1.14 D; p = 0.03), and all measurements with the 14-mm ring (1.0 +/- 1.49 D) versus the 18-mm ring (2.14 +/- 1.51 D; p = 0.04.). CONCLUSIONS: Significant IA can occur with placement of fixation rings, especially when suture placement is near the insertions of the rectus muscles.

Astigmatism↗
PubMed2001

Baclofen overdose in two siblings.

Baclofen is a muscle relaxant used in both adults and children with neuromuscular disorders to control spasticity. In children, relatively few cases of overdose have been previously reported. We report two cases of baclofen overdose occurring in two siblings. One sibling with cerebral palsy was being treated with baclofen at the time of overdose. Both cases presented with severe respiratory depression requiring mechanical ventilation. Serum baclofen concentrations from both children were significantly elevated. We also review the published literature on baclofen overdose in children and adolescents. These cases emphasize the importance of warning parents about the potential toxicity of baclofen when prescribing the drug to a family member.

Baclofen↗
PubMed2000

Bcl-2 protects neuronal cells against taxol-induced apoptosis by inducing multi-nucleation.

Taxol-induced peripheral neuropathy is a commonly-occurring side-effect in the treatment of cancer patients with taxoteres or taxanes. Taxol is known to induce apoptosis in a number of tumor cells. This report documents that, similar to proliferating cells, taxol induces apoptosis in NGF-differentiated PC12 cells, as assessed by exogenous FITC-annexin-V binding and nuclear fragmentation. It is shown that PC12 cells that stably overexpress Bcl-2 are protected against the toxic effect of taxol, as evidenced by the XTT assay and by a decreased fraction of propididum iodide positive cells in a dye exclusion test. Also the number of annexin-V-positive cells and the number of fragmented nuclei are lower in the Bcl-2 transfected cells. The effect is similar to the protective effect of Bcl-2 against NGF deprivation in differentiated PC12 cells. Although taxol forced both wild-type and Bcl-2-overexpressing cells into a mitotic state, only in Bcl-2-overexpressing cells did this lead to the appearance of metabolically active, multi-nucleated cells. This suggests that Bcl-2 is able to induce an alternative escape pathway, downstream of the G2/M block, in taxol-treated differentiated PC12 cells.

Animals↗
PubMed2000

Bcl-2 protects against apoptosis-related microtubule alterations in neuronal cells.

Bcl-2 is a gene with clear anti-apoptotic properties in neurodegenerative conditions. One of the earliest hallmarks of degeneration in neuronal cell cultures is the loss of neurite morphology. Therefore the effect of Bcl-2 on neuronal morphology and microtubule stability was studied in nerve growth factor differentiated PC12 cells. Microtubule dynamics were modulated using the microtubule stabilizer taxol and the microtubule destabilizer, okadaic acid, a protein phosphatase inhibitor. It was shown that Bcl-2 protects against both taxol- and okadaic acid induced neurite retraction. Bcl-2 overexpression also significantly reduced the increased ratio of acetylated tubulin over total tubulin induced by taxol treatment. Interestingly, Bcl-2 attenuates the decrease of the same ratio after exposure to okadaic acid, suggesting that Bcl-2 is able to normalize the level of acetylated tubulin. In addition, cell death and nuclear fragmentation, induced by okadaic acid, were reduced in Bcl-2 overexpressing cells. This protection is either downstream or independent of tau phosphorylation as quantitative immunocytochemistry with AT8 showed that Bcl-2 did not modify the level of tau phosphorylation. The data suggest that the protective effect of Bcl-2 on the neuronal cytoskeleton is probably linked to changes in the post-translational modification of tubulin.

Acetylation↗
PubMed1999

Bcl-2 protects against FCCP-induced apoptosis and mitochondrial membrane potential depolarization in PC12 cells.

This report addresses the relation between Bcl-2 and mitochondrial membrane potential (DeltaPsi(m)) in apoptotic cell death. Rat pheochromocytoma (PC12) cells are differentiated into neuron-like cells with nerve growth factor (NGF). It is known that Bcl-2 can attenuate apoptosis induced by deprivation of neurotrophic factor. The protective effect of Bcl-2 has been correlated with preservation of DeltaPsi(m). Protonophores, such as carbonyl cyanide p-trifluoromethoxyphenylhydrazone (FCCP), collapse the proton gradient across the mitochondrial inner membrane, resulting in a complete abolition of the mitochondrial membrane potential. Based on the analysis of morphology, of phosphatidylserine exposure and of nuclear fragmentation we conclude that FCCP induces apoptosis in PC12 cells, which can be prevented by overexpression of Bcl-2. To determine whether the cytoprotective effect of Bcl-2 is due to stabilization of DeltaPsi(m), we investigated the effect of Bcl-2 on changes in DeltaPsi(m), induced by FCCP in PC12 cells. We showed that treatment with FCCP induced a reduction in DeltaPsi(m), as assessed with the lipophilic cationic membrane potential-sensitive dye JC-1, and that Bcl-2 protects against FCCP-induced changes in NGF differentiated PC12 cells. Our data indicate that Bcl-2 protects against FCCP-induced cell death by stabilizing DeltaPsi(m).

Animals↗
PubMed1996

Self-injury in trauma survivors: 1. functions and meanings.

Self-injury is increasingly linked to traumatic childhood experiences, and is identified in this paper as a means by which some trauma survivors cope with post-traumatic effects. It is proposed that self-injury serves a number of functions, organized here into four categories: re-enactment of the original trauma, expression of feelings and needs, reorganization of the self, and management of dissociative process.

Adaptation, Psychological↗
PubMed1996

Self-injury in trauma survivors: 2. levels of clinical response.

Responding effectively to trauma survivors who engage in self-injury can be challenging, even for experienced therapists. This paper outlines therapeutic goals and appropriate clinical responses, including remaining present at and open to communication about disclosures of self-injury, helping clients to intervene in their own process of self-injury, and working with clients to resolve underlying issues. Alternatives to self-injury are discussed and cautions are offered about common therapeutic responses likely to be particularly unhelpful.

Countertransference↗
PubMed1994

Adult survivors of childhood sexual abuse: survivor's disclosure and nurse therapist's response.

Recent literature pertinent to adult survivors suggests that childhood sexual abuse is a serious problem, and that disclosure is on the rise. The aftereffects of childhood sexual abuse can cause dysfunction in various aspects of the survivor's physical and mental health. Understanding the traumagenic dynamics of childhood sexual abuse and its aftereffects provides direction for the nurse therapist during both the client's disclosure and intervention planning. This knowledge assists the therapist in promoting mental health and healing, as well as providing comfort for the therapist. The nurse therapist's reactions to the client's disclosure can affect the way the client feels about disclosure and the therapeutic relationship. If a negative message is conveyed to the survivor at the time of disclosure, the feelings of betrayal, stigmatization, and powerlessness that the survivor experienced as a child will be replicated. This can damage the therapeutic relationship and delay the healing process. When disclosure is received and acted upon in a sensitive, therapeutic manner, the survivor is empowered and can enter with the nurse therapist into an effective therapeutic alliance. Nurse therapists should gain awareness of the types of emotional responses that can be engendered in the health professional during disclosure. Awareness of these emotional reactions can lead to the identification of coping strategies useful to both the therapist and the adult survivor. Coping strategies useful to the therapist include maintaining adequate boundaries, understanding oneself and one's responses to sexual-abuse issues, utilizing ongoing consultation or supervision, and preventing burnout.(ABSTRACT TRUNCATED AT 250 WORDS)

Adaptation, Psychological↗
PubMed1993

An evaluation of the physical and functional characteristics of infant resuscitators.

Self-inflating resuscitators (SIRs) are commonly used to assist ventilation in the newborn. Despite their widespread use, there is limited information available on the functional and physical characteristics of SIRs. We studied five new infant bag-valve units to compare their physical characteristics, including reservoir, accumulator, and dead space volumes (VD), pressure relief mechanism (PRM), inspiratory resistance (RI), and functional mechanics including stroke volume (SV), fraction of delivered oxygen (FDO2), and cycle frequency at -5 degrees C, 20 degrees C, and 49 degrees C, using a test lung apparatus and experienced respiratory therapists. In addition, deficiencies and features that may render them less than ideal were sought. All SIRs met minimum standards for reservoir and accumulator volumes, RI (< 20 cmH2O/L/sec), SV (20-70 ml), and FDO2 (> 90%) as determined by the Canadian Standards Association (CSA) and the American Society for Testing of Materials (ASTM). However, the following deficiencies were noted: 1) MPR and Pulmanex had no PRM (ASTM requirement); 2) MPR could not cycle at -5 degrees C; 3) the VDs for Pulmanex (10 ml) and MPR (15 ml) were high; 4) the CPR connector broke during normal use, and the MPR connector frequently disconnected; 5) the Laerdal expiratory valve was incompetent; and 6) the Laerdal and CPR could be misassembled for use. Our study shows that some commercially available SIRs do not meet all CSA and ASTM standards and may not be ideal in specific clinical situations. The choice of a SIR may be dictated by the clinical situation in which its use is intended.

Equipment Design↗
PubMed1992

Prolonged extracorporeal support for nonneonatal respiratory failure.

Extracorporeal membrane oxygenation (ECMO) is effective for newborns with pulmonary failure unresponsive to conventional therapy. However, ECMO for the older child and adult has been controversial and not widely utilized. Over 4 years, 24 patients (aged 4 months to 16 years; 11 boys, 13 girls) underwent venoarterial ECMO (duration, 7 to 19 days) for respiratory failure. The diagnoses were: viral pneumonia (7), hydrocarbon aspiration (6), sepsis with adult respiratory distress syndrome (ARDS) (2), bacterial pneumonitis (2), tracheal stenosis (1), bilateral pulmonary contusion (1), diaphragmatic hernia with ARDS (1), ketoacidosis with ARDS (1), pulmonary artery injection of hydrocarbon (1), drowning (1), and epiglottis with barotrauma (1). Pre-ECMO blood gas ranges (and means) were PO2 18 to 65 (46), and PCO2 47 to 112 (65). Nineteen patients received dopamine, dobutamine, or other inotrope for associated cardiac and/or renal failure. Cannulation for ECMO was through neck or groin vessels in 17, and sternotomy in 7. ECMO flow rates were 150 to 250 mL/kg/min, to maintain PO2 greater than 100 and PCO2 less than 40. Nine patients (41%) survived ECMO, with eight long-term survivors, (4 hydrocarbon aspiration or injection, 1 pulmonary contusion, 1 viral pneumonia, 1 ARDS, 1 barotrauma), three of whom have mild neurological deficit. All patients with sternotomy, and 8 of 15 with neck and/or groin cannulation, required 1 to 5 explorations for hemorrhage while on ECMO. All survivors had primarily pulmonary failure; patients with combinations of pulmonary, cardiac, and renal failure did not survive. ECMO can be life-saving in the child with isolated pulmonary failure, but its efficacy in patients with multiorgan failure is uncertain.

Adolescent↗
PubMed1992

Relationship of cross-brain oxygen content difference, cerebral blood flow, and metabolic rate to neurologic outcome after near-drowning.

We evaluated the relationship of global cerebral blood flow, cross-brain oxygen content difference, cerebral metabolic rate for oxygen, intracranial pressure, and cerebral perfusion pressure to functional neurologic outcome in 12 comatose children on 2 consecutive days after near-drowning. Five children survived with functional neurologic outcome; five died and two survived with severe neurologic damage. Children who survived with functional neurologic outcome had a significantly higher cross-brain oxygen content difference (7.89 +/- 2.62 vs 3.91 +/- 1.59 ml/dl; p = 0.028) at 24 hours and a higher cerebral metabolic rate for oxygen 48 hours after admission (3.19 +/- 2.86 vs 0.96 +/- 0.45 ml/100 gm per minute; p = 0.030) compared with those who died or survived in a damaged state. There were no significant differences in global cerebral blood flow, intracranial pressure, and cerebral perfusion pressure between groups at either 24 or 48 hours. Our preliminary data suggest that a higher cross-brain content difference value is an important early variable associated with functional neurologic recovery after near-drowning. However, a single cross-brain oxygen content difference value must be interpreted with caution because considerable variability may occur among patient groups.

Adolescent↗
PubMed1992

An evaluation of the physical and functional characteristics of resuscitators for use in pediatrics.

OBJECTIVE: To evaluate the physical and functional characteristics of pediatric self-inflating resuscitators. DESIGN: Tested under simulated clinical conditions. Results were analyzed by descriptive analysis. SETTING: A pulmonary laboratory in a university hospital. METHODS: Eight new pediatric self-inflating resuscitators were obtained from the manufacturers and evaluated for functional characteristics including: a) fraction of delivered oxygen at 10 L/min and a tidal volume of 300 mL; b) maximum stroke volume against no resistance; and c) maximum cycling frequency at -5 degrees C, 20 degrees C, and 48 degrees C. The resuscitators were also evaluated for physical characteristics, including potential for misassembly, pressure relief valves, expiratory valve leak, and inspiratory resistance. RESULTS: All resuscitators met the minimum standards of the Canadian Standards Association and American Standards for Testing of Materials. However, one bag cycled at only 32 breaths/min at -5 degrees C, marginally within accepted standards. Only five self-inflating resuscitators had pop-off valves. These valves malfunctioned, with valve activation occurring well above the accepted standards. Three of the self-inflating resuscitators could be misassembled for use. Four of the resuscitators were unable to deliver tidal volumes required for preoxygenation in a 20-kg child. CONCLUSIONS: While these self-inflating resuscitators met the minimum standards, they are all unable to deliver 100% oxygen. One unit is probably not appropriate in the out-of-hospital setting when ambient temperatures are less than 0 degrees C. Those resuscitators that can be misassembled are dangerous in unskilled hands. In addition, reliance on pop-off valve activation to limit airway pressure is dangerous.

Child↗
PubMed1990

Mucosal proliferation characteristics in ureterosigmoidostomy: effect of calcium supplement.

Ureterosigmoidostomy, frequently performed in children for urinary diversion, is a known premalignant condition. Dietary calcium supplements have been shown to normalize mucosal proliferative patterns in other human premalignant colonic conditions, which might decrease the risk of cancer. However, calcium supplementation has not been investigated in ureterosigmoidostomy. We used a rat model to study the effects of increased dietary calcium on the progression to carcinoma in ureterosigmoidostomy. Twenty-five Wister rats underwent ureterosigmoidostomy by anastomosis of bladder trigone and ureters to sigmoid, and were divided into two groups: group 1, regular diet (14); and group 2, calcium supplemented (2%) diet (11). All animals received the diet for 9 months. At death the anastomosis was weighed and examined histologically. In addition, ornithine decarboxylase (ODC), an enzyme involved in polyamine synthesis that becomes elevated in neoplastic and proliferative disorders, was determined at the anastomosis and 8 cm proximal (normal colon). All animals developed proliferative metaplastic polyposis at the anastomosis. Tumor weights were 2.6 +/- 1.1 g for group 1 and 4.8 +/- 1.2 g for group 2 (P less than .05). The ODC levels were: group 1, normal colon 78.2 +/- 15.6 and tumor 321.3 +/- 58.8 (P less than .002); and group 2, normal colon 425.8 +/- 65.4 and tumor 568.0 +/- 40.9 (P = NS). The difference between group 1 normal colon and group 2 normal colon was significant (P less than .001), as was group 1 tumor and group 2 tumor (P less than .02).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Neurosonographic changes in newborns treated with extracorporeal membrane oxygenation.

Ten out of 40 near-term neonates on extracorporeal membrane oxygenation (ECMO) therapy developed abnormal neurosonograms. We identified two abnormal patterns. Hyperechoic areas of intracranial hemorrhage were observed in two patients (a significantly lower incidence than previously reported). Diffuse or focal echogenic areas of hypoxia-ischemia resulting from periventricular leukomalacia, cerebral edema or large vessel infarction had not previously been noted in nine of these patients. Three of the ten patients survived with neurological sequelae. Recognition of hemorrhage or a hypoxic-ischemic pattern should serve as a warning to initiate or accelerate the weaning of infants from ECMO.

Brain Diseases↗
PubMed1986

Duodenal atresia: a comparison of techniques of repair.

Although duodenal atresia is a common cause of congenital intestinal obstruction, the optimal technique of repair remains controversial. In a 10-year period, 41 newborns (20 male, 25 premature) underwent either side-to-side duodenoduodenostomy (SDD, 10 infants), side-to-side duodenojejunostomy (SDJ, 9 infants), or diamond-shaped duodenoduodenostomy (DDD, 22 infants) in a nonrandomized series. One-layer anastomosis was used in each case, and gastrostomy was placed in most patients. Groups were compared for survival, prematurity, associated anomalies, time until feeding onset, total hospitalization time, and complications. The three groups were identical for survival (all 100%), prematurity (60% SDD, 67% SDJ, 59% DDD), and serious associated anomalies (cardiac, gastrointestinal, Down's; 33% SDD, 44% SDJ, 50% DDD). The time until feeding onset was shortest with DDD (4.1 +/- 0.4 days), compared with 8.0 +/- 1.1 days for SDD and 9.6 +/- 1.9 days for SDJ (both P less than .05 v DDD). Total hospitalization was significantly less in DDD (16.2 +/- 2.1 days) v 24.2 +/- 3.1 days for SDD (P less than .05) and 28.3 +/- 4.3 days for SDJ (P less than .01). One complication necessitating reoperation occurred in each group (SDD, adhesions; SDJ, stenotic anastomosis; and DDD, missed second atresia). These data suggest that DDD is superior to SDD and SDJ for repair of duodenal atresia, resulting in earlier feeding and discharge.

Duodenal Obstruction↗
PubMed1986

Extracorporeal membrane oxygenation for newborn respiratory failure.

Jugular vein-carotid artery extracorporeal membrane oxygenation (ECMO) was utilized in 22 newborns (16 male and 6 female) 1 to 12 days old with respiratory failure due to meconium aspiration (12 patients), diaphragmatic hernia (4), persistent fetal circulation (3), hyaline membrane disease (2), and Rh incompatibility (1). Prior to ECMO, all patients had alveolar-arterial O2 pressure gradients greater than 580 mm Hg (predicted mortality greater than 90%), weighed more than 1,800 gm, had a gestation period of longer than 35 weeks, and had no cerebral hemorrhage. The duration of ECMO was 41 to 310 hours (mean, 134.5 hours). Nineteen (86%) of the 22 patients survived ECMO. Death was caused by lung disease (2) and cerebral hemorrhage (1). Four other patients died 6 to 40 days after ECMO of pulmonary hypoplasia (1), pneumonia (1), cerebral edema (1), and hepatorenal failure (1). Complications during ECMO were few and easily managed. Fifteen infants (68%) are alive 1 to 18 months after ECMO. Three have neurological deficit (2 severe, 1 mild). Bayley Developmental Examinations in 4 survivors now more than 12 months old are normal. Extracorporeal membrane oxygenation is an aggressive but effective technique of life support in newborns refractory to conventional respiratory management. Potential complications of ECMO mandate strict aseptic technique, constant monitoring, and multidisciplinary patient management.

Female↗