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Biomedical subjects

A Morris

Publications and source records attributed to A Morris.

At least 145 records · Page 8Linked to original sources
PubMed1995

Placenta accreta encountered during dilation and evacuation in the second trimester.

OBJECTIVE: To assess the frequency of placenta accreta encountered during dilation and evacuation (D&E) in the second trimester. METHODS: Among 16,827 second-trimester D&E procedures performed at our hospitals and clinics, seven cases of placenta accreta, either suspected clinically or proven histologically, were encountered. These cases were analyzed for history of prior cesarean delivery, placenta localization, and histology of hysterectomy specimens. RESULTS: Six of the seven cases suspected clinically were confirmed histologically. All placenta accreta patients had at least one cesarean delivery (mean 1.7), and five had a preoperative sonogram demonstrating some form of placenta previa. The prevalence of clinical placenta accreta encountered during D&Es in the second trimester was 0.04%, the same as that reported for placenta accreta diagnosed clinically in the third trimester. CONCLUSION: Placenta accreta can be a potential complicating factor in the patient undergoing D&E in the second trimester.

Abortion, Induced↗
PubMed1995

The prevalence of different human papillomavirus types and p53 mutations in laryngeal carcinomas: is there a reciprocal relationship?

This study investigates whether a reciprocal association occurs between HPV infection and somatic mutation of the tumour suppressor gene p53 in laryngeal carcinomas. Using immunohistochemical techniques, 87 tumours were examined for expression of the mutant form of p53 phosphoprotein using the monoclonal antibody PAB 1801. The prevalence of different HPV types in these tumours was determined by using the polymerase chain reaction and restriction enzyme analysis. Over-expression of p53 was noted in 50/87 (57.5%) of the tumours investigated but not in any of the non-neoplastic laryngeal mucosa (controls). There was no statistical correlation between p53 immunoreactivity and the clinicopathological parameters of laryngeal carcinomas. HPV DNA was detected in 8/36 (22.2%) of the tumours: HPV-6 in three, HPV-11 in one, HPV-16 in two, and unknown HPV type in two. In p53-mutant tumours, HPV was present in 4/20 tumours but none of these were high risk HPV types. In p53-normal tumours, on the other hand, HPV was present in 4/16 tumours but two of these were definitely high risk HPV-16. These results imply the reciprocal association between HPV and somatic mutations of p53 found in the case of cervical carcinoma.

Base Sequence↗
PubMed1995

Vertebral column injuries and lap-shoulder belts.

OBJECTIVE: To present cases of vertebral column fractures or fracture dislocations that occur to restrained front seat occupants where there is no evidence of body contact with interior car components based on both medical records and car inspection. MATERIALS AND METHODS: Reviewed were car crash injury cases investigated at the University of Michigan Transportation Research Institute and at the University of Birmingham (England) as well as the National Accident Severity Study files of the National Highway Traffic Safety Administration. Medical records and car inspections in the cases presented did not indicate any evidence of body contact with interior car structures. MAIN RESULTS: Vertebral fractures or fracture dislocations sustained by front seat occupants who were wearing lap-shoulder belts are rare, as evidenced by the relatively few cases identified in the literature and in the crash injury files reviewed. CONCLUSIONS: Infrequently, in frontal crashes, vertebral fractures or fracture dislocations can occur to lap-shoulder belted front seat car occupants without head or torso impacts with interior car structures. Cervical spine injuries are due to neck flexion over the shoulder portion of the restraint. Thoracolumbar fractures can occur in the frontal crash even at low crash velocity.

Accidents, Traffic↗
PubMed1995

Over-expression of tumour suppressor gene p53 in laryngeal squamous cell carcinomas and its prognostic significance.

p53 is a nuclear phosphoprotein which acts as a tumour suppressor factor, regulating cell growth and division. Mutations in the p53 gene appear to be the most common genetic alterations in human cancer. The aim of this study was to investigate p53 expression in laryngeal squamous cell carcinomas and to assess its role as a marker of prognostic significance. Using immunohistochemical staining techniques, a series of laryngeal carcinomas (n = 87) were examined for expression of the mutant form of p53 phosphoprotein using the monoclonal antibody PAB 1801. p53 over-expression was noted in 50 biopsies of laryngeal carcinomas (57.5%) but not in any of the non-neoplastic laryngeal mucosa which were used as the control. There was no statistical correlation between p53 immunoreactivity and the clinicopathological parameters of the cancers including: site of tumour, TNM staging, differentiation grading and tumour recurrence. These findings indicate that p53 expression is strongly associated with carcinoma cells and not with normal cells in the larynx. However, p53 expression is probably unrelated to the biological aggressiveness of these tumours.

Antibodies, Monoclonal↗
PubMed1995

General primer-mediated polymerase chain reaction for simultaneous detection and typing of human papillomavirus DNA in laryngeal squamous cell carcinomas.

The aim of this study was to investigate the prevalence of different human papillomavirus (HPV) types in laryngeal squamous cell carcinomas using general primer-mediated polymerase chain reaction (PCR). Tumour sections from 42 patients with laryngeal carcinomas were investigated. For HPV DNA amplification, consensus primers were used which were directed to the L1 coding region of the HPV genome. Analysis of the PCR products was done using 2% agarose gel electrophoresis followed by restriction enzyme analysis to identify different HPV types. Amplification of the human TGF-beta 1 DNA was successfully performed in 36/42 (85.7%) of samples confirming the presence of sufficient DNA for viral amplification. HPV DNA was detected in 8/36 (22.2%) of the tumours examined (three HPV-6, two HPV-16, one HPV-11, two unknown HPV types). HPV DNA was not detected in any of the non-neoplastic laryngeal mucosa which was used as control (n = 15). Fifty per cent of women had HPV-positive tumours compared with 8% of men (chi2 = 5.8, P < 0.05). Our data indicate that while the overall prevalence of HPV in laryngeal carcinomas is fairly high (22.2%), the frequency of high-risk types (HPV-16 & HPV-18) is low (5.5%). HPV probably acts as a promoter in the multistep process of carcinogenesis in squamous mucosal cells of the larynx.

Aged↗
PubMed1995

Evolutionary dynamics of the FMR1 locus.

Rare haplotypes for close flanking markers are associated with increased allele size and frequency of the fragile X mutation. Exceptional founder haplotypes can be identified, but many haplotypes with rare alleles contribute to full mutations. A transition matrix constructed from the data predicts that a population with reduced variability will manifest a slowly increasing frequency of premutations and full mutations, reach a distribution close to the observed one after a few hundred generations, and then slowly be depleted of these alleles. This prediction is opposite to less well supported inference of increasing frequency of progressive amplification, but the data are inadequate to reach any firm conclusions. Factors that may determine the evolution of these systems, but cannot now be evaluated, are discussed.

Biological Evolution↗
PubMed1995

Activation by interferon-gamma of expression of ICAM-1 and MHC class II antigens in tumour cells from colorectal carcinomas.

Aims-To determine whether lack of MHC class II antigen and intercellular adhesion molecule-1 (ICAM-1) expression in some tumours is due to the inability of the tumour cells to respond to the cytokine interferon-gamma (IFN-gamma), an important activator of these surface molecules.Methods-Cells from 40 colorectal tumours which did not constitutively express class II MHC antigens or ICAM-1 were kept in short term culture after disaggregation for a few days to two weeks without significant loss of viability. These were treated with IFN-gamma. Expression of class II MHC antigens and ICAM-1 was determined using immunohistological techniques.Results-There was clear induction in vitro of both MHC class II antigens and ICAM-1 in cells from eight of the tumours, with between 50 and 80% of the tumour cells in the cultures staining positively. The staining was apparent within 24 hours, appeared maximal at about three days, and declined thereafter. There were no obvious differences in cell morphology or viability between the cultures which were inducible and those which were not, nor were there obvious differences between the tumours from which they were derived.Conclusions-Expression of MHC class II antigens and ICAM-1 may be induced by IFN-gamma in a small proportion of colorectal tumours which do not constitutively express these antigens, showing that only a minority of tumours are capable of responding to this cytokine.

Journal Article↗
PubMed1995

Induction of intercellular adhesion molecule 1 and class II histocompatibility antigens in colorectal tumour cells expressing activated ras oncogene.

Aims-To determine whether there is a correlation between activation of the ras oncogene and the induction of MHC class II antigens and intercellular adhesion molecule 1 (ICAM-1) by interferon-gamma (IFN-gamma).Methods-Expression of class II antigens, ICAM-1 and intracellular ras oncoprotein (p21) in established colorectal cell lines and short term cultures of primary colorectal tumour cells was determined by flow cytometry and mutation in the ras gene by sequencing of amplified segments of the gene.Results-The cell lines showed a variation in their modulation of MHC class II antigens and ICAM-1, ranging from no induction to a 98-fold increase in class II antigen expression in the HT29 cell line. Previous work indicated that most tumours could not be induced to express class II antigens. Four of the five least inducible lines either contained mutant ras or highly expressed the oncoprotein. The four highly inducible cell lines all contained non-mutant ras. Of the 21 tumours studied in primary culture, 10 were inducible, one of which contained mutant ras. Of the remaining non-inducible tumours, four were mutant.Conclusions-Correlations between ras activation and failure to respond to IFN-gamma could not be shown to be significant. Therefore, ras activation, and concomitant subversion of intracellular signalling pathways, is probably not the major determinant in failure to activate class II antigens and ICAM-1.

Journal Article↗
PubMed1994

Effect of carboxyterminal modification on the oligomeric structure of human beta hemoglobin.

A broad beta chain band region containing multiple components was observed with both native beta and Des(His-146, Tyr-145) beta chains following isoelectric focusing on agarose gels (pH 6.0-8.0). In contrast to the tetramer-monomer system of beta chains, a distinct separation of three components (tetramer, dimer and monomer) was seen for Des(His-146, Tyr-145) beta chains indicative of an oligomeric structural beta model with a stable dimer species. Protein dilution (500 to 15.6 microM in heme) amplified the more cathodic (presumably dimeric and monomeric) components of these chains, and titration with partner alpha chains resulted in a selective depletion of the monomer (most cathodic) component which could be quantitatively correlated with assembly of the hemoglobin tetramer.

Crystallography, X-Ray↗
PubMed1994

Tumour necrosis factor alpha and interleukin-1 beta induce specific subunits of NFKB to bind the HIV-1 enhancer: characterisation of transcription factors controlling human immunodeficiency virus type 1 gene expression in neural cells.

In human astrocytoma and neuroblastoma cell lines tumour necrosis factor alpha (TNF alpha) and interleukin 1 beta (IL-1 beta) induced NFKB and an additional KB-specific protein of approximately 80 K to bind the HIV-1 enhancer. One nucleoprotein complex contained prototypical NFKB comprising of p50 and p65 subunits and a second contained the p65 subunit and an 80 K factor, p80. Over a 24 hr period of cytokine stimulation the p50/p65 complex of NFKB was present in the nucleus whilst the second complex declined in abundance after two hours due to the decline of p80. In unstimulated cells, DNAse I footprinting revealed a previously unidentified octamer-like binding site in the negative regulatory element (NRE) of the HIV-1 long terminal repeat (LTR) which specifically bound protein factors present in human astrocytoma, neuroblastoma and murine oligodendroglioma cell lines. A second unique motif, also in the NRE, was observed with extracts from one human neuroblastoma cell line and a murine oligodendroglioma. Footprinting analysis also confirmed that Sp1, TATA, Site A and Site B motifs of the LTR were occupied by nuclear factors present in neural cells.

Astrocytoma↗
PubMed1994

Report of the American-European consensus conference on ARDS: definitions, mechanisms, relevant outcomes and clinical trial coordination. The Consensus Committee.

The acute respiratory distress syndrome (ARDS), a process of non-hydrostatic pulmonary edema and hypoxemia associated with a variety of etiologies carries a high morbidity, mortality (10-90%) and financial cost. The reported annual incidence in the United States is 150,000 cases, but this figure has been challenged and may be different in Europe. Part of the reason for these uncertainties is the heterogeneity of diseases underlying ARDS and the lack of uniform definitions for ARDS. Thus, those whose wish to know the true incidence and outcome on this clinical syndrome are stymied. The European American Consensus Committee on ARDS was formed to focus on these issues and on the pathophysiologic mechanisms of the process. It was felt that international coordination between North America and Europe in clinical studies of ARDS was becoming increasingly important in order to address the recent plethora of potential therapeutic agents for the prevention and treatment of ARDS.

Clinical Protocols↗
PubMed1994

Report of the American-European Consensus conference on acute respiratory distress syndrome: definitions, mechanisms, relevant outcomes, and clinical trial coordination. Consensus Committee.

The acute respiratory distress syndrome (ARDS), a process of nonhydrostatic pulmonary edema and hypoxemia associated with a variety of etiologies, carries a high morbidity rate, mortality rate (10% to 90%), and financial cost. The reported annual incidence in the United States is 150,000 cases, but this figure has been challenged and may be different in Europe. Part of the reason for these uncertainties is the heterogeneity of diseases underlying ARDS and the lack of uniform definitions for ARDS. Thus, those who wish to know the true incidence and outcome of this clinical syndrome are stymied. The European American Consensus Committee on ARDS was formed to focus on these issues and on the pathophysiologic mechanisms of the process. It was felt that international coordination between North America and Europe in clinical studies of ARDS was becoming increasingly important to address the recent plethora of potential therapeutic agents for the prevention and treatment of ARDS.

Clinical Trials as Topic↗
PubMed1994

The American-European Consensus Conference on ARDS. Definitions, mechanisms, relevant outcomes, and clinical trial coordination.

The acute respiratory distress syndrome (ARDS), a process of nonhydrostatic pulmonary edema and hypoxemia associated with a variety of etiologies, carries a high morbidity, mortality (10 to 90%), and financial cost. The reported annual incidence in the United States is 150,000 cases, but this figure has been challenged, and it may be different in Europe. Part of the reason for these uncertainties are the heterogeneity of diseases underlying ARDS and the lack of uniform definitions for ARDS. Thus, those who wish to know the true incidence and outcome of this clinical syndrome are stymied. The American-European Consensus Committee on ARDS was formed to focus on these issues and on the pathophysiologic mechanisms of the process. It was felt that international coordination between North America and Europe in clinical studies of ARDS was becoming increasingly important in order to address the recent plethora of potential therapeutic agents for the prevention and treatment of ARDS.

Americas↗