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Biomedical subjects

D O'Connor

Publications and source records attributed to D O'Connor.

At least 73 records · Page 4Linked to original sources
PubMed1997

Efficacy of psychosocial treatments for noisemaking in severe dementia.

Noisemaking is one of the most disturbing behavior disorders associated with dementia. Standard management practices, including pharmacological interventions, are not very successful in treating the behavior. Very little research has been carried out to evaluate innovative treatments or to determine the etiology of noisemaking. In this article, we report on a series of 12 case studies in which we tested the efficacy of some psychosocial interventions in reducing the frequency of noisemaking in long-term-care residents with severe dementia. Interventions were contingent reinforcement of quiet behavior and environmental stimulation tailored to individual preferences. Of the 12 patients recruited into the study, 2 died during the course of observations, 3 were not observed to be as noisy as reported by staff, and 3 showed a clear reduction in noise during the intervention period. Four patients did not show any overall reduction in noisemaking during psychosocial interventions. Future research could differentiate between types of interventions in successful cases and attempt to control further for the consistent application of interventions by long-term-care staff.

Aged↗
PubMed1997

Immunization registry: problems and prospects for boosting vaccine coverage of children.

Case studies are presented on three organizational models for immunization registries in local communities: agency-based, facility-based, and population-based systems. The strengths and limitations of the respective approaches are highlighted. Each model faces three similar challenges: generating "real-time" information on the status of children who fall behind on their immunizations, assuring confidentiality of registrants and medical information, and maintaining operations amidst adverse social conditions that are at the root of underimmunization of children. With sufficient resources and cooperation among many private and public interests, registries have considerable potential to increase vaccination coverage among our population.

Child↗
PubMed1997

In vivo skeletal responses to porous-surfaced implants subjected to small induced motions.

Cylindrical porous-coated implants were placed in the distal femoral metaphyses of twenty dogs and were subjected to zero, twenty, forty, or 150 micrometers of oscillatory motion for eight hours each day for six weeks with use of a specially designed loading apparatus. The in vivo skeletal responses to the different magnitudes of relative motion were evaluated. Histological analysis demonstrated growth of bone into the porous coatings of all of the implants, including those that had been subjected to 150 micrometers of motion. However, the ingrown bone was in continuity with the surrounding bone only in the groups of implants that had not been subjected to motion or that had been subjected to twenty micrometers of motion; in contrast, the implants that had been subjected to forty micrometers of motion were surrounded in part by trabecular bone but also in part by fibrocartilage and fibrous tissue, and those that had been subjected to 150 micrometers of motion were surrounded by dense fibrous tissue. Trabecular microfractures were identified around three of the five implants that had been subjected to forty micrometers of motion and around four of the five that had been subjected to 150 micrometers of motion, suggesting that the ingrown bone had failed at the interface because of the large movements. The architecture of the surrounding trabecular bone also was altered by the micromotion of the implant. The implants that had stable ingrowth of bone were surrounded by a zone of trabecular atrophy, whereas those that had unstable ingrowth of bone were surrounded by a zone of trabecular hypertrophy. The trabeculae surrounding the fibrocartilage or fibrous tissue that had formed around the implants that had been subjected to forty or 150 micrometers of motion had been organized into a shell of dense bone tangential to the implant (that is, a neocortex outside the non-osseous tissue).

Animals↗
PubMed1997

Craniofacial skeletal fixation using biodegradable plates and cyanoacrylate glue.

This study examined the feasibility of fixation of craniofacial bone using Lactosorb biodegradable plates adhered to bone with butyl-2-cyanoacrylate adhesive (Histoacryl) in a pig. The stability and bone-healing characteristics of this rigid fixation method were studied and compared with standard rigid fixation using metal plates and screws on osteotomy sites in the frontal bones and infraorbital rims. Rectangular osteotomies (2.0 x 3.0 cm) were performed on the right and left sides of the frontal bone and wedge-shaped osteotomies (1.5 x 1.7 cm) were made on the left and right infraorbital rims in seven Yorkshire pigs. Metal plates were applied with screws to the osteotomies on one side, and the other side was fixed with a biodegradable plate and butyl-2-cyanoacrylate. The animals were sacrificed at 8 weeks, and both sides were compared biomechanically and histologically. Radiographic, biomechanical, and histologic analyses were performed to evaluate skeletal stability, contour, accurate positioning of bony fragments, bone healing, and maximum torque to failure of the repair sites. Clinical and radiographic observations demonstrated stability of the bone fragments without any evidence of displacement. According to Student's t test for paired data, no statistical difference was found in the maximum torque to failure of fragments fixed with biodegradable plates and glue compared with those fixed with metal plates and screws (p > 0.05), whether or not a gap existed at the osteosynthesis site. Although the sample size was small, no differences were noted between the two types of treatment groups. This study demonstrates that rigid internal fixation of osteotomized cranial bone fragments using biodegradable plates and butyl-2-cyanoacrylate is as effective as metal plate and screw fixation in this animal model.

Animals↗
PubMed1996

Catalytic properties of human manganese superoxide dismutase.

The depletion of superoxide catalyzed by human manganese superoxide dismutase (MnSOD) was observed spectrophotometrically by measuring the absorbance of superoxide at 250-280 nm following pulse radiolysis and by stopped-flow spectrophotometry. Catalysis showed an initial burst of activity lasting approximately 1 ms followed by the rapid emergence of a greatly inhibited catalysis of zero-order rate. These catalytic properties of human MnSOD are qualitatively similar to those reported for MnSOD from Thermus thermophilus (Bull, C., Niederhoffer, E. C., Yoshida, T., and Fee, J. A.(1991) J. Am. Chem. Soc. 113, 4069-4076). However, there are significant quantitative differences; the emergence of the inhibited form is approximately 30-fold more rapid for human MnSOD. The turnover number for human MnSOD at pH 9.4 and 20 degrees C was kcat = 4 x 10(4) s-1 and kcat/Km = 8 x 10(8) M-1 s-1, determined by a simulated fit of the model of Bull et al. (1991) to the pulse radiolysis data. We also report that the maximum of the visible absorption spectrum of human MnSOD (epsilon480 = 525 M-1 cm-1) showed a strong dependence on pH that could be described by an ionization of pKa 9.4 +/- 0.1 with a maximum at low pH.

Base Sequence↗
PubMed1995

p53 phosphorylation mutants retain transcription activity.

To investigate the effect of phosphorylation on the transcription activity of p53, ten phosphorylation mutants were constructed covering all the identified phosphorylation sites of rat p53. These included mutants of two casein kinase I sites (Ser6 and Ser9), two DNA-PK sites (Ser15 and Ser39), a p34cdc2 site (Ser313), the adjacent Ser312 and a casein kinase II site (Ser390). Two double phosphorylation mutants (Ser4, 6 and Ser15, 390) and one triple phosphorylation mutant (Ser4, 6 and 15) were also constructed. The transcription activity of all the p53 phosphorylation mutants was tested by transfection into two different types of cells, Saos-2 cells and p53(-/-) fibroblasts derived from p53 knock out mice, which both lack endogenouse p53. Surprisingly, all the p53 phosphorylation mutants retain transcription activity and the seven mutants tested can also suppress cell growth.

Animals↗
PubMed1995

Biomechanical evaluation of the canine and porcine models for experimental craniofacial surgery.

This investigation compared the variation of the biomechanical properties of canine and porcine craniofacial bones in homotypical (same site in opposite sides of an animal) and heterotypical (same site in different animals) sites. Biomechanical analysis is a reliable method to assess bone healing, because fracture repair correlates closely with the changes in biomechanical properties. Paired bone fragments were harvested in nine dogs and nine minipigs from each side of the skull from three different sites-the frontal bone, the supraorbital rim, and the zygomatic arch- and submitted to torque to failure. Maximum torque, stiffness, and toughness were recorded and comparative analysis performed. A normal range of variation between paired craniofacial bones in two useful animal models is provided. The results showed that the variability between homotypic left and right sides was not significant, whereas the variability between heterotypic sites in separate animals was. Maximum torque was the most reliable of the three parameters considered, because the data fell over a much narrower range. We conclude that the use of the contralateral side is a valid control in experimental procedures that may alter the biomechanical properties of one side.

Analysis of Variance↗
PubMed1995

Cyanoacrylate fixation of the craniofacial skeleton: an experimental study.

This study examined the feasibility of achieving bone fixation of the upper facial skeleton using n-butyl-2-cyanoacrylate. We compared the fixation obtained with this adhesive to that obtained with plates and screws in an animal model. The stability of fixation of both osteotomies and onlay grafts was studied in six minipigs. Three osteotomies were performed on each side of the skull. Additionally, a parietal split-thickness autograft was fixated to the nasal bone as an onlay. Plates and screws were used on the right and adhesive on the left. The animals were killed at 6 weeks, and both sides were compared biomechanically and histologically. Clinical assessment showed stability of all fragments. No statistical difference was found in the comparison of the maximum torque to failure between analogous plated and glued sides. Radiographic cephalometry revealed no significant displacement of the fragments. Histologic analysis demonstrated bony union. In this study, n-butyl-2-cyanoacrylate was as effective as plates and screws in the fixation of surgically created osteotomies of the upper facial skeleton.

Animals↗
PubMed1995

Cerebral iron oxide distribution: in vivo mapping with MR imaging.

PURPOSE: To map the distribution of an iron oxide label in the central nervous system with in vivo magnetic resonance (MR) imaging. MATERIALS AND METHODS: Unilateral osmotic disruption of the blood-brain barrier (BBB) in rats (n = 40) was followed by injection of monocrystalline iron oxide nanoparticles (MION) into the carotid artery. MR images (1.5 T) were obtained in and ex vivo, and results were correlated with histologic section-matched iron maps. RESULTS: A mean of 0.2% of the injected MION was found in the brain 24 hours after unilateral osmotic disruption of the BBB. The spatial distribution of iron oxide within the brain correlated with areas known to have high relative perfusion. Iron was found in cell bodies and dendrites of cortical neurons and astrocytes and in the interstitial space. The threshold in concentration for detection of MION in the brain was 62.2 ng Fe/mm2. CONCLUSION: MR imaging is well suited to noninvasive in vivo mapping of the intracerebral iron oxide distribution.

Animals↗
PubMed1994

Carbon catabolite repression in Kluyveromyces lactis: isolation and characterization of the KIDLD gene encoding the mitochondrial enzyme D-lactate ferricytochrome c oxidoreductase.

In the "petite-negative" yeast Kluyveromyces lactis carbon catabolite repression of some cytoplasmic enzymes has been observed. However, with respect to mitochondrial enzymes, in K. lactis, unlike the case in the "petite-positive" yeast Saccharomyces cerevisiae, growth on fermentable carbon sources does not cause repression of respiratory enzymes. In this paper data are reported on carbon catabolite repression of mitochondrial enzymes in K. lactis, in particular on L- and D-lactate ferricytochrome c oxidoreductase (LCR). The L- and D-LCR (E.C. 1123, E.C. 1124) in yeast catalyze the stereospecific oxidation of D and L isomers of lactate to pyruvate. This pathway is linked to the respiratory chain, cytochrome c being the electron acceptor of the redox reaction. We demonstrate that the level of mitochondrial D- and L-LCR is controlled by the carbon source, being induced by the substrate lactate and catabolite-repressed by glucose. We cloned the structural gene for D-LCR of K. lactis (KlDLD), by complementation of growth on D,L-lactate in the S. cerevisiae strain WWF18-3D, carrying both a CYB2 disruption and the dld mutation. From the sequence analysis an open reading frame was identified that could encode a polypeptide of 579 amino acids, corresponding to a calculated molecular weight of 63,484 Da. Analysis of mRNA expression indicated that glucose repression and induction by lactate are exerted at the transcriptional level.

Amino Acid Sequence↗
PubMed1994

Incidence of dementia in a population older than 75 years in the United Kingdom.

BACKGROUND: Incidence studies have been relatively neglected in psychiatric epidemiology. They are particularly important for dementia, since prevalence rates are affected by length of survival, which itself falls with increasing age and presence of dementia. METHODS: Two-wave community study of 1195 elderly subjects aged older than 75 years, restudied 2.4 years after a community prevalence study. A two-stage method was used, comprising the Mini-Mental State Examination followed in a stratified sample by the Cambridge Examination for Mental Disorders of the Elderly (CAM-DEX) interview. Incidence rates were based on person-years at risk. RESULTS: Annual incidence rates for dementia were 2.3% for subjects initially aged 75 to 79 years, 4.6% for ages 80 to 84 years, and 8.5% for ages 85 to 89 years, approximately doubling every 5 years. Rates did not differ significantly by sex, educational level, or social class. Twice as many additional individuals received a diagnosis of minimal dementia not reaching case threshold. CONCLUSIONS: The findings show high rates of new onset dementia, increasing markedly with age, and suggest rapid acceleration of one or more processes that is common in advanced age.

Age Distribution↗
PubMed1994

Clinical stage IB endometrial adenocarcinoma with an isolated small bowel metastasis.

Although patients with widely disseminated endometrial adenocarcinoma can have tumor involving the intestine, a focal metastasis to the small bowel with no other evidence of extra-uterine spread has not been reported. A patient with a clinical stage IB, grade 2 superficially invasive endometrial adenocarcinoma was found to have an isolated distant metastasis to the small intestine. The patient has been asymptomatic and disease free for almost 4 years following postoperative treatment with whole abdominal radiation therapy on a Gynecologic Oncology Group protocol. The finding of a solitary small bowel metastasis was not predictable based on the current understanding of the biologic behavior of endometrial adenocarcinomas. This case emphasizes the need for a thorough abdominal exploration in patients with endometrial adenocarcinoma by surgeons trained to detect and resect abdominopelvic tumors, and it validates the need for innovative treatment protocols for women with gynecologic malignancies.

Anastomosis, Surgical↗