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Biomedical subjects

E Jones

Publications and source records attributed to E Jones.

At least 127 records · Page 7Linked to original sources
PubMed1996

The use of intracellular single-chain antibody fragments to inhibit specifically the expression of cell surface molecules.

One possible method to inhibit specifically the function of a protein inside a cell is to express an intracellular antibody combining site that can block function or prevent expression of the targeted molecule. In this report the parameters involved in the production and expression of functional, endoplasmic reticulum-retained, single chain Fv antibody fragments (scFv) were investigated. These intracellular scFv constructs were tested for their ability to inhibit specifically the expression of a CHO cell line pretransfected with the relevant cell surface antigen CD2. No scFv was detected in the cell supernatant although functional scFv, as assayed by ELISA, was detected in an NP-40 soluble fraction if an N-linked glycosylation site had been introduced into the antibody construct. This demonstrates that functional antibody combining sites can be produced even though they are not secreted. Inhibition of CD2 was obtained but was not complete and differed between clones. Levels of scFv could be increased by gene amplification but the level of functional binding activity remained constant and no further inhibition of CD2 expression was obtained. Immunofluorescence analysis at the single-cell level of the permeabilised transfected cell lines showed that less than 8% of cells expressed detectable levels of intracellular scFv, indicating selection against cells producing high levels of single-chain antibody. This selection was not seen when comparable single-chain TCR constructs, known to be retained intracellularly, were used. Thus, production of scFv with binding activity is not sufficient for good inhibition of gene expression although introduction of an N-linked glycosylation site is beneficial. The best strategy is probably to screen a panel of scFv constructs and use those that are secreted rather than those that are retained intracellularly.

Amino Acid Sequence↗
PubMed1996

Preliminary results for positron emission mammography: real-time functional breast imaging in a conventional mammography gantry.

In order to optimally integrate radiotracer breast imaging within the breast clinic, anatomy and pathology should be easily correlated with functional nuclear medicine breast images. As a first step in the development of a hybrid functional/anatomic breast imaging platform with biopsy capability, a conventional X-ray mammography gantry was modified to image the compressed breast with positron emitters. Phantom studies with the positron emission mammography (PEM) device showed that a 1-cc hot spot could be detected within 5 min. A preliminary clinical trial demonstrated in vivo visualization of primary breast cancer within 4 min. For sites where positron-emitting radionuclides are available, PEM promises to achieve low-cost directed functional examination of breast abnormalities, with the potential for achieving X-ray correlation and image-guided biopsy.

Breast↗
PubMed1996

Endocytosis and recycling of neurokinin 1 receptors in enteric neurons.

Neurotransmission depends on the availability of transmitter and on the presence of functional, high-affinity receptors at the plasma membrane that are capable of binding ligand. The pathway, mechanism and function of endocytosis and recycling of the substance P or neurokinin 1 receptor in enteric neurons were studied using fluorescent substance P, receptor antibodies and confocal microscopy. In both the soma and neurites, substance P induced rapid, clathrin-mediated internalization of the neurokinin 1 receptor into early endosomes, which also contained the transferrin receptor. After 4-8 h, there was a return in surface neurokinin 1 receptor immunoreactivity in the soma, which was not prevented by cycloheximide, and was thus independent of new protein synthesis. This return was prevented by acidotropic agents, therefore required endosomal acidification. This suggests that the neurokinin 1 receptor recycles in the soma. In contrast, in neurites, substance P and the neurokinin 1 receptor remained in endosomes and recycling was not detected. Neurons of the myenteric plexus were heavily innervated by substance P-containing nerve fibers, and K(+)-stimulated release of endogenous substance P from cultured neurons induced internalization of the neurokinin 1-receptor. Therefore, endogenous substance P may induce endocytosis of the neurokinin 1 receptor. In the soma, endocytosis and recycling correlated with loss and recovery of functional binding sites for substance P. suggesting that this process contributes to the regulation of peptidergic neurotransmission. Thus, ligand-induced endocytosis of the neurokinin 1 receptor in myenteric neurons is associated with a loss of surface receptors and functional binding sites. Since release of endogenous substance P induces neurokinin 1 receptor internalization, and neurokinin 1 receptor neurons are innervated by substance P-containing fibers, endocytosis of neuropeptide receptors may regulate neurotransmission.

Animals↗
PubMed1996

Limited Radiation Therapy for Selected Patients With Pathological Stages IA and IIA Hodgkin's Disease.

The first definitive reports that early stages Hodgkin's disease (HD) could be cured by radiotherapy were published by Vera Peters in 1950 and by Easson and Russell in 1963. Since then, advances in understanding the natural history, refining the histopathologic classification, and development of a staging system have improved the management of HD. Several studies of early stage HD show greater than 80% actuarial 10- to 15-year freedom from relapse, and less than a 10% mortality from HD after treatment with radiation therapy alone. Radiotherapy has become so successful in the treatment of early stage HD (with combination chemotherapy reserved for relapse) that the risk of dying from other causes approaches the risk of dying from HD itself at 15 to 20 years following treatment. This article outlines the principles of treatment for favorable prognosis clinical stages IA and IIA HD, with emphasis on identifying patients with favorable features who may be treated effectively with mantle irradiation only.

Journal Article↗
PubMed1996

Extended harvest times are not necessary for the detection of in vitro clastogens in regulatory cytogenetics studies.

The choice of harvest time in in vitro cytogenetics assays is a critical factor in determining the sensitivity of the assay for detecting clastogenic potential. As yet there is no harmonization of regulatory requirements in this aspect. It has been suggested that the use of extended harvest times can improve the sensitivity of detecting some chemicals which either induce cell cycle delay or produce lesions which induce chromosome aberrations at divisions subsequent to the first post-treatment mitosis. The incidence of such chemicals encountered in the routine testing of chemicals for regulatory submissions is not known. Therefore a large database of 550 chemicals tested in nine laboratories using standard regulatory protocols, including a late harvest time, was assessed for the incidence of chemicals uniquely positive only at a delayed harvest time. The number of such chemicals was very low ( < 0.2%) and the chromosome damage induced by these chemicals may not result from direct genotoxic mechanisms. Based on these data it is recommended that there is no need to include an extended harvest time in in vitro cytogenetics assays except where it might help to resolve an equivocal result.

Animals↗
PubMed1996

Autosomal dominant polycystic kidney disease--the patient on renal replacement therapy.

In Europe approximately 6% of all patients on chronic renal replacement therapy suffer from polycystic kidney disease. Survival of patients with polycystic kidney disease on renal replacement therapy is better than for other primary renal diseases, despite a similar cardiovascular risk profile. We documented a significantly higher erythropoietin level in polycystic patients even in advanced uraemia and on dialysis. A better haemoglobin level seems to improve long-term survival because of a possible beneficial effect on cardiac function. There is no increased risk of renal cell carcinoma in patients with autosomal dominant polycystic kidney disease. Polycystic patients on dialysis should be followed for cardiac valve abnormalities and cerebral aneurysms.

Cardiovascular Diseases↗
PubMed1996

Social support: some pragmatic implications for health care professionals.

The role of social support in promoting recovery from chronic illness has been the focus of a debate within the nursing and social science research communities. This paper reviews the literature on this important issue and discusses the implications for patient management. In providing holistic patient care, health care professionals need to reflect on the impact of this research for their clinical practice.

Chronic Disease↗
PubMed1996

Decision making in resuscitation from out of hospital cardiac arrest.

OBJECTIVE: To determine which factors are perceived by senior house officers (SHOs), consultants, and medical registrars in accident and emergency (A&E) medicine as being important in decision making. METHODS: 132 SHOs in A&E medicine, of 172 attending an induction course at the start of their job (77%), completed a questionnaire relating to 20 factors of possible importance in decision making; 73 completed the questionnaire at six weeks and 55 at six months. Ten medical registrars and 31 consultants in A&E medicine also completed the questionnaire. RESULTS: The SHOs were able to recognise bystander cardiopulmonary resuscitation and early advanced I support, as well as the presence of ventricular fibrillation, as important prognostic factors. There was considerable variation in all three groups in their opinions on the importance of the other factors considered. There was no obvious change in SHO responses over the period of training. CONCLUSIONS: Lack of guidelines may result in more patients receiving resuscitation than are salvageable, as doctors maintain a low threshold for continuing resuscitation to avoid missing potential survivors. A decision making algorithm is recommended.

Attitude of Health Personnel↗
PubMed1996

Evidence for a tumor suppressor gene distal to BRCA1 in prostate cancer.

PURPOSE: The breast-ovarian cancer susceptibility gene, BRCA1, has been implicated by both epidemiologic and genetic studies to be involved in prostate cancer. We wished to test the frequency of BRCA1 deletion and that of other markers in the region of proximal 17q in prostate tumor cells. MATERIALS AND METHODS: We used a dual-color fluorescence in situ hybridization (FISH) assay using P1 phage probes for the BRCA1 gene and 3 flanking sites at 17q12-21, as well as a chromosome 17 centromere-specific alpha-satellite probe, to detect deletions in single-cell suspensions and touch preparations from 23 primary clinical stage B prostate tumors and adjacent nontumor prostate tissues. Lymphoblastoid cells and prostate cells from a normal donor were used to determine control loss values. RESULTS: Significant loss (p < 0.05) of at least 1 of the P1s was detected in 16 of 23 (70%) cases, and in 4 of those cases all markers were lost, consistent with whole chromosome loss. Of the 12 cases with subchromosomal loss, 8 had loss distal to BRCA1. Loss was detected in 5 cases previously reported by using allelic imbalance (AI) methodologies, and was detected in an additional 11 non-AI cases, suggesting that FISH is more sensitive than AI for deletion detection in prostate tumor cells. CONCLUSIONS: The data suggest that the region distal to BRCA1 may contain 1 or more prostate-specific tumor suppressor genes and that BRCA1 itself plays only a minor role in prostate cancer development.

BRCA1 Protein↗
PubMed1996

Mesenchymal cell activation is the rate-limiting step of granulation tissue induction.

During wound repair a 3-day lag occurs between injury and granulation tissue development. When full-thickness, 8-mm-round, excisional wounds were made in the paravertebral skin of outbred Yorkshire pigs and harvested at various times, no granulation tissue was observed before day 4. Day 4 wounds were 3% filled with granulation tissue, day 5 wounds 48% filled, and day 7 wounds 88% filled. The prerequisites for granulation tissue induction are not known but hypothetically include fibrin matrix maturation or cell activation. To examine whether matrix maturation was necessary, wounds were allowed to heal for 5 or 7 days and then aggressively curetted, resulting in the formation of fresh fibrin clots in the newly formed wound spaces. In contrast to original wounds, no lag phase was observed; wounds curetted on day 5 were 23% filled with granulation tissue 1 day later and 99% filled 3 days later, whereas wounds curetted on day 7 were 47% filled 1 day later and completely filled within 2 days. Thus, granulation tissue formation resumed promptly and independently of fibrin clot matrix maturation. This observation suggested that mesenchymal cell activation might be the rate-limiting step in granulation tissue formation. To address this hypothesis more directly, cultured porcine or human fibroblasts, grown to 80% confluence in Dulbecco's minimal essential medium plus 10% fetal calf serum, were added to new wounds. These wounds were sealed with a freshly made exogenous fibrin clot. In some wounds, platelet releasate was added to the fibrin clot. Granulation tissue did not form in day 3 wounds, which had received either fibrin alone, fibrin and platelet releasate, or fibrin and fibroblasts. In contrast, granulation tissue was observed in wounds receiving fibrin, human fibroblasts, and platelet releasate. By day 4, wounds receiving cultured human fibroblasts, fibrin, and platelet releasate were 14% filled with granulation tissue compared with less than 4% granulation tissue in control wounds. Thus, fibroblast activation is a limiting step of granulation tissue formation, and continued cell stimulation is required for accelerated development.

Animals↗
PubMed1995

Loss of chromosome 17 loci in prostate cancer detected by polymerase chain reaction quantitation of allelic markers.

Using a polymerase chain reaction/microsatellite marker system, we demonstrated that 6 of 22 (27%) clinical stage B (early) primary prostate tumors showed loss of heterozygosity at one or more of five loci on chromosome 17. The sensitivity of this study was increased by use of a PhosphorImager and statistical analysis of replicate tumor-normal DNA pairs. Two patients showed tumor-specific interstitial loss at a locus in close proximity to the familial breast cancer gene BRCA1. These findings suggest that genes on the proximal long arm of chromosome 17 play a pivotal role in the early development of at least a subset of prostatic tumors.

Alleles↗