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Biomedical subjects

M Gordon

Publications and source records attributed to M Gordon.

At least 19 recordsLinked to original sources
PubMed1992

In vitro expression and secretion of functional mammalian intrinsic factor using recombinant baculovirus.

Intrinsic factor was produced at levels of 1-2 mg per 1 (0.25 micrograms per 10(6) cells) by growth of recombinant baculovirus-infected Sf9 cells in spinner culture. The recombinant IF showed a binding affinity for cobalamin (2.6.10(-10) M) and for the intrinsic factor-cobalamin receptor (3.5.10(-10) M) nearly identical with native IF. Purification of the recombinant intrinsic factor could be accomplished by affinity chromatography, but final purification by gel chromatography (FPLC) was necessary to separate intrinsic factor from a 62 kDa protein secreted from uninfected Sf9 cells. This protein binds selectively to the cobalamin-Sepharose column, but demonstrates no cobalamin binding activity after elution. Microgram quantities of radiolabelled protein could be produced for metabolic and autoradiographic studies. The stability of intrinsic factor to pancreatic proteinases was nearly identical with human gastric intrinsic factor, both native and recombinant as produced in mammalian cells. Glycosylation of the intrinsic factor was demonstrated by lectin binding to the recombinant protein separated on SDS-PAGE, and by a shift in apparent molecular mass from 47 kDa to 43 kDa following treatment of Sf9 cells with tunicamycin. Most of the recombinant IF was produced by Sf9 cells in the first 48 h post infection.

Animals↗
PubMed1992

Efficacy of 131I ablation following thyroidectomy in patients with invasive follicular thyroid cancer.

The role of thyroid ablation following thyroidectomy for invasive follicular cancer remains controversial. The use of iodine 131 (131I) ablation as adjuvant therapy may facilitate follow-up of patients in whom serum thyroglobulin levels and 131I total body scans are used to detect metastatic disease. It is uncertain if 131I ablation improves survival of patients with follicular thyroid cancer. Thus, the purpose of this study was to determine if survival is enhanced following ablation, with particular reference to those patients with minimally invasive cancer. Between the years 1955 to 1988, 142 patients with invasive thyroid follicular cancer were treated at the British Columbia Cancer Agency, of whom 71 had minimal invasion and no extrathyroidal extension of tumor. In this group of patients, 46 underwent hormone suppression only, 17 had ablation, and 8 had neither. The average follow-up was 9 years and extended beyond 15 years in many patients. Data were entered in a mainframe computer, and Kaplan-Meier survival analysis was used, comparing crude survival, disease-specific survival, and disease-free survival. There was no significant difference between groups. In patients with follicular thyroid cancer and capsular invasion only, 131I ablation does not improve survival compared with patients treated with thyroid hormone suppression only.

Adenocarcinoma↗
PubMed1992

Human p150,95 alpha-subunit: genomic organization and analysis of the 5'-flanking region.

LFA-1, Mac-1, and p150,95 comprise a family of cell-surface glycoproteins that mediate adhesive interactions of myeloid and lymphoid cells. These glycoproteins are heterodimers composed of a common beta-subunit and distinct alpha-subunits. The chromosomal gene for the alpha-subunit of p150,95 was isolated to provide a framework from which to study the mechanisms for expression of the gene. The gene spans 30 kb of DNA and contains 31 exons. In agreement with a previous report by Corbi et al. (1990), the exons were found to be divided into five groups separated by large introns. The extracellular domains are encoded in exons 2 through 30 while the transmembrane and cytoplasmic domains are encoded in exons 30 and 31. We have expanded these findings in a number of ways. The first exon contains the 5' untranslated region. The 2,163-bp 5'-flanking sequence contains the first intron and several putative transcriptional initiation sites preceded by two TATA sequences and two GC-like boxes. Additional sequence motifs for a variety of DNA-binding proteins are present and discussed. Fusions of the bacterial chloramphenicol acetyltransferase gene (CAT) to approximately 5.3 kb of 5'-flanking DNA and also to subcloned fragments of this region were constructed and transfected into the human promonocytic cell line, U937. CAT expression was inducible with phorbol-12-myristate-13-acetate (PMA) and full expression was dependent on the presence of intron 1 and sequences upstream from the 2,163-bp flanking DNA. Additionally, intron 1 and a region further upstream contain functional cis-acting sequences.

Base Sequence↗
PubMed1992

Prevalence of hepatitis B surface antigen, hepatitis C antibody, and HIV-1 antibody among residents of a long-term-care facility.

OBJECTIVE: To determine the prevalence of hepatitis B antigen (HBsAg), antibody to hepatitis C virus (anti-HCV), and antibody to human immunodeficiency virus (anti-HIV) among residents of a long-term care facility. DESIGN: Anonymous unlinked serosurvey. SETTING: Accredited university-affiliated long-term-care facility in Toronto with 300 chronic-care hospital patients, 350 nursing home residents, and 200 residents of a senior citizens' apartment complex. INTERVENTIONS: Sera from left-over blood samples obtained from residents in November 1990 were tested for HBsAg, anti-HCV, and anti-HIV using standard methods. RESULTS: A total of 508 sera were tested. The number (%) positive for HBsAg, anti-HCV, and anti-HIV, respectively were: 3(0.6%), 7(1.4%), and 0(0%). CONCLUSIONS: This is the first report defining rates of infection with bloodborne infective agents among residents of a long-term care facility. These results support the use of hepatitis B vaccine for medical and nursing staff and the implementation of universal precautions in long-term care facilities.

Aged↗
PubMed1992

Transplantation of cultured premyelinating oligodendrocytes into normal and myelin-deficient rat brain.

Cultures of oligodendroglial cells at various stages of maturation, from progenitors to maturing oligodendrocytes, were prepared from neonatal rat brain primary cultures and then were prelabeled in the culture dish with the fluorescent dye, fast blue (FB). Single cell suspensions were grafted into normal or myelin-deficient rat brains. The normal as well as the myelin-deficient in vivo environment allowed cell survival, migration, and differentiation. The FB+ cells expressed the oligodendroglial markers, glycerol phosphate dehydrogenase, galactocerebroside, and myelin basic protein. In the normal rat transplanted cells were identifiable at all times studied up to 24 weeks. Extensive migration of FB+ cells was observed in whole-brain sagittal sections. Our results show that the plasticity of oligodendroglia differentiation, extensively studied in vitro, can now be investigated in the normal and myelin-deficient in vivo environment.

Animals↗
PubMed1992

Factors predicting postoperative sentence scores in postlinguistically deaf adult cochlear implant patients.

A sample of 64 postlinguistically profoundly to totally deaf adult cochlear implant patients were tested without lipreading by means of the Central Institute for the Deaf (CID) sentence test 3 months postoperatively. Preoperative promontory stimulation results (thresholds, gap detection, and frequency discrimination), age, duration of profound deafness, cause of deafness, lipreading ability, postoperative intracochlear thresholds and dynamic ranges for electrical stimulation, depth of insertion of the electrode array into the scala tympani, and number of electrodes in use were considered as possible factors that might be related to the postoperative sentence scores. A multiple regression analysis with stepwise inclusion of independent variables indicated that good gap detection and frequency discrimination during preoperative promontory testing, larger numbers of electrodes in use, and greater dynamic ranges for intracochlear electrical stimulation were associated with better CID scores. The CID scores tended to decrease with longer periods of profound deafness.

Adolescent↗
PubMed1992

Dental anxiety and oral health in young Israeli male adults.

Dental anxiety may be a serious limiting factor in providing adequate dental treatment. The present study sought to define the prevalence of dental anxiety in a cross-section of young Israeli adults (389 male Israeli army recruits) to correlate anxiety scores with their oral health status and to compare the findings with existing data. The main stimuli triggering anxiety were found to be in the following descending order: seeing the needle, feeling the drill, and feeling pain despite local anaesthesia. A positive correlation was found between the degree of anxiety and the dental status; the highest percentage of untreated patients was found in the high anxiety group. It is concluded that young adult Israeli males manifest dental anxiety in a manner similar to that reported in the United States and Sweden. Dental anxiety may be an important factor in the avoidance of seeking dental care.

Adolescent↗
PubMed1991

A phase I trial of recombinant human interleukin-1 beta alone and in combination with myelosuppressive doses of 5-fluorouracil in patients with gastrointestinal cancer.

We studied escalating doses of recombinant human interleukin-1 beta (IL-1 beta) alone and after a myelosuppressive dose of 5-fluorouracil (5-FU) in patients with gastrointestinal cancer. Transient neutropenia, monocytopenia, and lymphocytopenia were observed followed by a 1.3- to 6.0-fold (mean, 3.46-fold) dose-dependent neutrophil leukocytosis (P less than .00001) on the days of IL-1 beta administration. Increases in platelet counts were observed at a median of 14 days (range, 6 to 23) after IL-1 beta administration. Transient hypoglycemia, rebound hyperglycemia, elevations in serum cortisol, and C-reactive protein were observed. Side effects included fever, rigors, and headache in the majority of patients. Hypotension was observed in three of five patients at the highest dose level (0.1 micrograms/kg) and was dose-limiting. Fewer days of neutropenia were noted after 5-FU plus IL-1 beta than after 5-FU alone; however, this difference did not reach statistical significance. These data show that IL-1 beta has stimulatory effects in human hematopoiesis.

Adult↗
PubMed1991

Assessment of competency: the role of neurobehavioral deficits.

We present a practical set of guidelines for assessing competency in patients with cognitive deficits due to neurologic disorders such as stroke, head injury, Alzheimer disease, and multi-infarct dementia. Our focus is the evaluation of cognitive processes underlying the ability to make competent decisions, with an emphasis on the identification of areas of preserved function that may be used to bypass intellectual deficits. The assessment of the cognitive processes underlying competency involves a series of steps designed to evaluate attention, language, memory, and frontal lobe function. The examiner must first show that the patient has an adequate level of attention for participation in the further testing of specific cognitive functions; second, that the patient is able to comprehend relevant instructions, retain information long enough to evaluate it in relation to relevant recent and remote experiences, and express his or her wishes; and finally, that the patient has sufficiently intact judgment and awareness. The examiner must determine whether the patient's preserved cognitive abilities are sufficient for him or her to make an adequate judgment in relation to the specific question being asked. If cognitive function is found to be significantly impaired, the examiner should do a detailed assessment for the presence of compensatory abilities that can be used to bypass the deficits. For example, the examiner should assess whether patients who cannot speak are still able to express their wishes by pointing, using gesture, or even by drawing pictures. Unless such an assessment has been done, patients should not be considered incompetent.

Attention↗
PubMed1991

Interferon-alpha overrides the deficient adhesion of chronic myeloid leukemia primitive progenitor cells to bone marrow stromal cells.

Primitive blast colony-forming cells (BI-CFC) from chronic myeloid leukemia (CML) patients are defective in their attachment to bone marrow-derived stromal cells compared with normal BI-CFC. We investigated the effect of recombinant interferon-alpha 2a (IFN-alpha) on this interaction between hematopoietic progenitor cells and bone marrow-derived stromal cells by culturing normal stromal cells with IFN-alpha (50 to 5,000 U/mL). At 50 U/mL we found that: (1) the capacity of stromal cells to bind two types of CML primitive progenitor cells (BI-CFC and long-term culture-initiating cells) was increased; and (2) the amount of sulfated glycosaminoglycans (GAGs) in the stromal layer was increased. However, sulfated GAGs were not directly involved in binding CML BI-CFC, unlike binding by normal BI-CFC, which is sulfated GAG-dependent. Neuraminidase-treated control stromal cells bound an increased number of CML BI-CFC, reproducing the effect of IFN-alpha, whereas the binding to IFN-alpha-treated stromal cells was unaffected by neuraminidase treatment. Thus, the enhanced attachment by primitive CML progenitor cells to INF-alpha-treated stromal cells might be due to changes in the neuraminic acid composition in the stromal cell layer. Our in vitro evidence may provide insights into the mechanism of action of IFN-alpha in vivo. Prolonged administration may alter the marrow microenvironment in some patients such that it can restrain the aberrant proliferation of Philadelphia chromosome (Ph)-positive stem cells while permitting Ph-negative stem cells to function normally.

Bone Marrow↗
PubMed1991

Adapting milieu therapy to short-term psychiatric hospitalization of children.

Traditional concepts of long-term residential treatment of children are adapted for use on short-term psychiatric units. A model of milieu therapy is proposed which emphasizes the fostering of discriminate interpersonal attachments. Specific interventions, the use of limits, and the role of other therapies are discussed in the context of this model.

Child↗