Biomedical subjects

L Harris

Publications and source records attributed to L Harris.

At least 55 records · Page 3Linked to original sources

PubMed1997

The Genome Sequence DataBase version 1.0 (GSDB): from low pass sequences to complete genomes.

The Genome Sequence DataBase (GSDB) has completed its conversion to an improved relational database. The new database, GSDB 1.0, is fully operational and publicly available. Data contributions, including both original sequence submissions and community annotation, are being accomplished through the use of a graphical client-server interface tool, the GSDB Annotator, and via GIO (GSDB Input/Output) files. Data retrieval services are being provided through a new Web Query Tool and direct SQL. All methods of data contribution and data retrieval fully support the new data types that have been incorporated into GSDB, including discontiguous sequences, multiple sequence alignments, and community annotation.

Animals↗

PubMed1997

Arrhythmia and mortality after the Mustard procedure: a 30-year single-center experience.

OBJECTIVES: Our purpose was to assess the risk factors for late mortality, loss of sinus rhythm and atrial flutter after the Mustard operation. BACKGROUND: The Mustard operation provides correction of cyanosis with low surgical risk in transposition of the great vessels. However, right ventricular failure, loss of sinus rhythm, atrial flutter and death are frequent long-term complications. METHODS: Records of 534 children who underwent the Mustard operation at a single center since 1962 were reviewed for demographic, anatomic, electrocardiographic and physiologic predictors and outcomes. RESULTS: There were 52 early deaths (9.7%). Survival analysis was undertaken for 478 early survivors with a mean follow-up interval of 11.6 +/- 7.2 years. There were 77 late deaths (16.1%), with sudden death (n = 31) the most frequent cause. Survival estimates were 89% at 5 years and 76% at 20 years of age. Risk factors were an earlier date of operation, operative period arrhythmia and an associated ventricular septal defect. Risk (hazard) of late death declined in the first decade, with further peaks in the second decade. Sinus rhythm was present in 77% at 5 years and 40% at 20 years. Loss of sinus rhythm was associated with previous septectomy, postoperative bradycardia and late atrial flutter. Freedom from atrial flutter was 92% at 5 years and 73% at 20 years of age. Risk factors for atrial flutter were the occurrence of perioperative bradyarrhythmia, reoperation and loss of sinus rhythm during follow-up. Risk of atrial flutter demonstrates a late increase. CONCLUSIONS: Ongoing loss of sinus rhythm and late peaks in the risk of atrial flutter and death necessitate continued follow-up.

Arrhythmias, Cardiac↗

PubMed1997

Comparative study of the ipsilateral full thickness forearm skin graft in closure of radial forearm flap donor site defects.

The early experience of our unit with the technique of ipsilateral full thickness forearm skin grafting of the radial forearm flap donor site defect is described. The technique provides the advantages of a full thickness skin graft whilst avoiding the need to harvest skin from a remote area. We have compared the results with that of split skin grafts used contemporaneously for the same purpose in our unit; the advantages and disadvantages are outlined. Continued success has encouraged us to utilize this technique routinely with certain modifications which we describe.

Cicatrix↗

PubMed1997

Small-dose propofol by continuous infusion does not prevent postoperative vomiting in females undergoing outpatient laparoscopy.

This study was designed to test the hypothesis that there is a direct prophylactic antiemetic effect of small-dose propofol given by continuous infusion. Sixty female patients undergoing outpatient laparoscopy under general anesthesia were randomized to receive, in a double-blind fashion, either a bolus of 0.1 mg/kg followed by a constant infusion of 1 mg.kg-1.h-1 of propofol or an equivalent volume of 10% Intralipid (placebo) beginning 30 min before induction of anesthesia and continuing until discharge from Stage I postanesthesia care unit (PACU). Anesthesia was induced and maintained in a standard fashion in all patients. The number of emetic episodes before and after discharge from PACU, nausea scores (11-point numerical scale), and time to discharge were evaluated. No significant differences between Intralipid and propofol were found for any of the outcome variables tested. While small-dose propofol is an effective adjuvant in reducing chemotherapy-induced emesis, we were unable to demonstrate any beneficial effect of propofol in reducing postoperative nausea and vomiting when used as the sole prophylactic medication in this patient population. Propofol may have a synergistic effect when administered with other antiemetics, or the specific antiemetic effect of propofol, if it exists, may be dose-dependent and the dose used in this study was below the efficacy threshold.

Adolescent↗

PubMed1997

Analysis of whole-cell fatty acid profiles of verotoxigenic Escherichia coli and Salmonella enteritidis with the microbial identification system.

Differentiation of strains within bacterial species, based on gas chromatographic analysis of whole-cell fatty acid profiles, was assessed with 115 strains of verotoxigenic Escherichia coli and 315 strains of Salmonella enteritidis. Fatty acid-based subgroups within each of the two species were generated. Variability of fatty acid profiles observed in repeat preparations from the same strain approached that observed between subgroups, limiting the usefulness of using fatty acid profiles to subgroup verotoxigenic E. coli and S. enteritidis strains.

Bacterial Toxins↗

PubMed1996

Supratentorial primitive neuroectodermal tumors in children.

A retrospective review of 36 children diagnosed with a supratentorial primitive neuroectodermal tumor (PNET) at the Hospital for Sick Children was performed for the period 1970-1995. All children but one received their initial treatment at our institution. There were 18 males and 18 females and the median age at diagnosis was 35 months. Twenty-two PNETs were lobar, 3 were deep in the hemisphere, and 10 were located in the pineal region. One child presented with intracranial leptomeningeal disseminated disease. The tumors were mostly undifferentiated although 22 had some evidence of differentiation along one or more neuroepithelial lines. Five children had a biopsy, 24 had subtotal resection, and 7 had gross total resection. Twenty-six children had adjuvant radiotherapy and 13 had chemotherapy. At last follow-up 30 patients were dead and 6 were alive. The median survival was 23 months and the 2, 3, and 5 year survivals were 50%, 34%, and 18% respectively. All of the survivors received craniospinal radiation and 4 received chemotherapy. There was a statistically significantly worse survival in young children. There was a trend to better survival in children treated since 1984, and in children undergoing gross total resection. Because of the extremely poor survival, we recommended that all children undergo gross total resection followed by chemotherapy. For children older than 3 years of age craniospinal radiation should also be given.

Antineoplastic Agents↗

PubMed1996

The significance of heregulin in breast cancer tumor progression and drug resistance.

The erbB-2 receptor plays an important role in the prognosis of breast cancer and is expressed at high levels in nearly 30% of tumors in breast cancer patients. While evidence accumulates to support the relationship between erbB-2 overexpression and poor overall survival in human breast cancer, understanding of the biological consequence(s) of erbB-2 overexpression remains elusive. The discovery of heregulin has allowed us to identify a number of related but distinct biological endpoints which appear responsive to signal transduction through the erbB-2/4 receptor. These endpoints of growth, invasiveness, and differentiation have clear implications for the emergence, maintenance, and/or control of malignancy, and represent established endpoints in the assessment of malignant progression in human breast cancer. Preliminary studies in vitro have shown that heregulin induces a biphasic growth effect on cells with erbB-2 overexpression. Interestingly, we observed that expression of heregulin correlates with a more aggressive/invasive, vimentin-positive phenotype in breast cancer cells lines. Therefore, we have postulated that heregulin is involved in breast cancer tumor progression. We have shown that heregulin induces in vitro chemoinvasion and chemotaxis of breast cancer cells as well as growth in an anchorage dependent and independent manner. Interestingly, a heregulin neutralizing antibody inhibits chemotaxis and results in cell growth inhibition and blockade of the invasive phenotype. Strikingly, genetically engineered cells which constitutively express heregulin demonstrate critical phenotypic changes that are associated with a more aggressive phenotype. Specifically, these cells are no longer dependent on estrogen for growth and are resistant to tamoxifen in vitro and in vivo, and moreover these cells metastasize to lymph nodes in athymic nude mice. These tumors appear to have lost bcl-2 expression as compared with the control tumors. In addition, presumably by activation/regulation of topoisomerase II, the heregulin-transfected cells become exquisitely sensitive to doxorubicin and VP-16. Clearly, mechanistic aspects of the erbB-2/4 and heregulin interaction need to be understood from a therapeutic standpoint which could provide additional insights into synergistic treatments for certain patients, or improve treatment regimens for a large number of women. The study of heregulin and its co-expression with erbB-2/4 receptor and the assessment of its involvement in the progression from the in situ stage of breast tumors to the invasive one will additionally increase the relevance of heregulin as a prognostic/diagnostic factor. We believe that our studies provide new insights into breast cancer diagnosis, prognosis, and treatment.

Breast Neoplasms↗

PubMed1996

Health personnel: perceived differences in professional relationships and work role.

This study questions the validity of the assumption that the workplace culture and experiences of health personnel are largely similar. The study compares nurses, occupational therapists, physiotherapists and speech therapists concerning their perceptions of professional issues within their own profession, and their perceptions of professional issues within the medical profession. Respondents completed a questionnaire containing 55 items referring to their own profession, and 55 items referring to the medical profession. Six scales were derived from the large survey instrument addressing issues regarding status/cohesiveness of the profession, professional relationships, and the role of the patient in health delivery in the respondent's profession, and in the medical profession. Nurses emerged as different to other health personnel on most dimensions. Few differences emerged among allied health professionals. Physiotherapists were more positive than occupational therapists about the status/cohesiveness of their profession, and regarded the contributions of the patient to health delivery as less important. Speech therapists did not differ significantly from occupational therapists on any dimension.

Adult↗

PubMed1996

Effect of rice cereal feedings on bone mineralization and calcium homeostasis in cow milk formula fed infants.

OBJECTIVE: We conducted a prospective randomized, single-blinded clinical trial to test the hypothesis that intake of formula plus cereals between the ages of 16 and 26 weeks postnatally (as compared to formula alone) would lead to lower bone mineral content (BMC), higher parathyroid hormone (PTH) concentration, lower serum calcium (Ca), magnesium (Mg) and osteocalcin (OC); and increased continuous night sleep. METHODS: At 16 weeks postnatally, 41 healthy, term infants were randomized to formula alone or formula and cereal. RESULTS: We found no significant differences in growth or sleep pattern, nor in BMC between groups. Serum PTH concentration was significantly increased in the cereal group at 26 weeks. CONCLUSION: We speculate that the increase in PTH is due to relative Ca deficiency or is responsive to increased phosphate load in the cereal group.

Animals↗

PubMed1996

Autogenous soft-tissue procedures and osseointegrated alloplastic reconstruction: their role in the treatment of complex craniofacial defects.

Between 1990 and 1994, twenty-seven patients with extraoral craniofacial defects were treated at the Craniofacial Osseointegration and Maxillofacial Prosthetic Rehabilitation Unit in Edmonton. Fourteen patients required management by a combination of alloplastic and autogenous techniques to optimize their reconstructive result. Autogenous soft-tissue procedures were performed almost twice as often in patients whose deformity was the result of trauma. Autogenous soft-tissue procedures included soft-tissue expansion, static facial slings, free and pedicled vascularized bone grafts, eyebrow reconstruction, brow lifts, and scar revisions. These reconstructive procedures are illustrated in three cases.

Adult↗

PubMed1996

A selective and differential medium for Vibrio harveyi.

A new medium, termed Vibrio harveyi agar, has been developed for the isolation and enumeration of V. harveyi. It is possible to differentiate V. harveyi colonies from the colonies of strains representing 15 other Vibrio species with this medium. This medium has been shown to inhibit the growth of two strains of marine Pseudomonas spp. and two strains of marine Flavobacterium spp. but to allow the growth of Photobacterium strains. Colonies displaying typical V. harveyi morphology were isolated from the larval rearing water of a commercial prawn hatchery with V. harveyi agar as a primary isolation medium and were positively identified, by conventional tests, as V. harveyi. This agar displays great potential as a primary isolation medium and offers significant advantages over thiosulfate-citrate-bile salts-sucrose agar as a medium for differentiating V. harveyi from other marine and estuarine Vibrio species.

Culture Media↗

PubMed1996

Active parental consent in school-based research. An examination of ethical and methodological issues.

To date, most school-based research has used passive parental consent. However, the Family Privacy Protection Act of 1995 aims to change these requirements. The proposed legislation requires written parental consent if minors are to be asked "sensitive" questions as part of any program or activity funded in whole or in part by the federal government. This act is representative of a growing trend toward restricting research involving minors. Whether or not this act is passed by Congress, two lines of concern are highlighted by this legislation. The first deals with ethical issues surrounding consent procedures. For instance, are parental rights compromised when active consent is not mandated? A second line of inquiry pertains to the effect of active consent procedures on response rates and sample bias. In this article, the authors discuss ethical issues surrounding passive and active consent procedures and then report response rates from two projects in which active consent procedures were implemented.

Adolescent↗

PubMed1996

The role of primary chemotherapy in early breast cancer.

Primary chemotherapy was first attempted in the early 1970s in an attempt to improve local control and survival in patients with large breast tumors. While it is now clear that primary chemotherapy can achieve high response rates and allow more conservative surgery, it is less apparent if survival is improved in these patients. It is logical, then, to consider moving this form of treatment to an earlier stage of disease in which the probability of resistant clones is less in patients with lower tumor burden. Many questions still remain unanswered in the evaluation of the role of primary chemotherapy in the treatment of early breast cancer: Is the best method of diagnosis fine needle aspiration or incisional biopsy? What diagnostic tests are important before chemotherapy? Can better conservative local treatment be achieved using the primary modality of chemotherapy? Is local control, disease response, and/or survival improved by using chemotherapy before local measures? Several important studies have been performed in the treatment of early stage disease with primary chemotherapy and will be discussed with these questions in mind. In addition, investigation of markers that predict response to chemotherapy may help us better select patients who would benefit from primary chemotherapy. Those patients who are determined to have a poorer prognosis would be candidates for novel investigational treatments.

Antineoplastic Agents↗

PubMed1996

Sudden cardiac death in the adult with congenital heart disease.

Preliminary results of a review of sudden cardiac death in the adult with congenital heart disease were presented at the Canadian Adult Congenital Heart (CACH) Network meeting during the Canadian Cardiovascular Society's annual meeting in October 1994. Of 125 patients who were known to have died, sufficient details were available for 92 to determine the circumstance of death. Sudden death occurred in 23 patients (estimated incidence 5.3 per 1000 patients followed per year) at an average age of 33.5 +/- 11.9 years. Surgical procedures included intracardiac repair in 12, palliative procedures in only six and no cardiac surgery in six. Nine patients with sudden death had Eisenmenger syndrome. Right or left ventricular abnormalities were present in 15 of 21 patients with premorbid echocardiographic evaluation. A prior history of ventricular arrhythmia was available in only three patients. Sudden death is a significant cause of mortality in adults with congenital heart disease. Determination of risk factors will be an important aspect of the patient database under development by the CACH Network.

Adult↗

PubMed1995

Efficient plasmid DNA replication in Xenopus egg extracts does not depend on prior chromatin assembly.

Small plasmids replicate efficiently in unfertilized Xenopus eggs provided they are injected before rather than after activation of the cell cycle. Here we use Xenopus egg extracts to test the hypothesis that efficient replication results from chromatin assembly prior to activation giving preloaded plasmids a head start toward the formation of a replicating pseudonucleus (Sanchez, J.A., Marek, D., and Wangh, L.J. (1992) J. Cell Sci. 103, 907-918). As in ovum, plasmid DNA preincubated in unactivated egg cytoplasmcytostatic factor extracts) replicate more efficiently after extract activation than does the same DNA added to the same extract after activation. Unlike in ovum, however, plasmids that replicate efficiently in vitro do not assemble into chromatin during preincubation and become topologically knotted instead. But even DNA knotting does not explain subsequent efficient replication. Also, plasmids preassembled into chromatin in vitro do not replicate efficiently in activated egg cytoplasm unless first preincubated in a CSF extract. We conclude that unactivated eggs contain replication-enhancing activities that can act independently of plasmid chromatin assembly and DNA topology. These postulated "preloading" factor(s) may be related to licensing factor, an activity that controls initiation of DNA replication in eukaryotic cells. The experimental conditions described here will permit characterization of preloading/licensing factor(s) in the context of a small plasmid substrate.

Animals↗

PubMed1995

Conformational similarity and systematic displacement of complementarity determining region loops in high resolution antibody x-ray structures.

Comparison of seven high resolution x-ray structures shows that the conformations of canonical complementarity determining region (CDR) loops, which are shared by these antibodies, are very similar. However, large spatial displacements (up to 2.7 A) of the essentially identical CDR loops become evident when the antibody beta-sheet frameworks, to which the loops are attached, are least-squares superposed. The loop displacements follow, and amplify, small positional differences in framework/loop splice points. Intradomain structural variability and, to a lesser extent, domain-domain orientation appear to cause the observed loop divergences. The results suggest that the selection of framework regions for loop grafting procedures is more critical than previously thought.

Amino Acid Sequence↗

PubMed1995

Coronary sinus morphology in patients with atrioventricular junctional reentry tachycardia and other supraventricular tachyarrhythmias.

BACKGROUND: Coronary sinus access by electrode catheters is easier in patients with atrioventricular junctional reentry tachycardia (AVJRT) than in patients with other supraventricular tachyarrhythmias. The reason for this has not been addressed. METHODS AND RESULTS: The size and shape of the proximal coronary sinus were measured in 15 patients with AVJRT and 14 control subjects after angiographic visualization. Coronary sinus dimensions, morphology, and angle of origin from the right atrium were measured. The proximal coronary sinus in patients with AVJRT was larger than in the control population. The mean ostium diameter was 12.2 +/- 2 mm compared with control dimensions of 8.5 +/- 1.5 mm, P = .00001. At a distance of 5 mm from the ostium, the coronary sinus measured 10.2 +/- 1.8 mm compared with 8.1 +/- 1.9 mm, P = .007. The dilatation persisted 10 mm into the coronary sinus, with a measurement of 9 +/- 1.4 mm compared with 7.6 +/- 2 mm, P = .04. In 73% of AVJRT patients, the proximal coronary sinus had the appearance of a wind sock. This morphology was seen only in 7% of control patients, in whom the coronary sinus was tubular (in 93%). There was considerable interindividual variability in the angle of origin. CONCLUSIONS: The proximal coronary sinus in patients with AVJRT was significantly different from a control population. The ostium was 44% larger and remained more dilated to at least 10 mm from the ostium. The appearance was like a wind sock in AVJRT patients and tubular in the control patients. These findings may have important implications for arrhythmia pathogenesis in such patients.

Adolescent↗

PubMed1995

Female adolescents of alcohol misusers: disordered eating features.

Studies show that children of alcohol-abusing parents constitute an at-risk population. This study attempted to understand the impact of parental alcohol misuse on the disordered eating behaviors of their female adolescent children, based on a sample of 532 teenagers from alcohol-misusing parents in Minnesota. These female adolescents had significantly higher prevalence rates of all the seven eating disordered symptoms that were studied. The study also identified a few protective factors: Those who did not develop any of the disordered eating symptoms were more satisfied with their present weight. Further, they worried less about abuse from parents and perceived that their school personnel cared about them.

Adolescent↗