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Biomedical subjects

P Jackson

Publications and source records attributed to P Jackson.

At least 163 records · Page 9Linked to original sources
PubMed1989

The application of high resolution two-dimensional polyacrylamide gel electrophoresis to the identification and purification of a protein, NG8.4, present in Neisseria gonorrhoea and the subsequent development of a radioimmunoassay.

A soluble protein of unknown function was shown, by two-dimensional polyacrylamide gel electrophoresis, to be present in Neisseria gonorrhoeae at significantly higher concentrations than in the other related bacteria tested. The data indicate the possibility of this protein being specific to Neisseria gonorrhoeae. This protein was designated as NG 8.4 and purified. A radioimmunoassay was developed for the measurement of this protein and subsequently used to determine the degree of cross reaction exhibited by a number of species of bacteria. Of the bacteria tested only those of the genus Neisseria gave a significant reaction in the assay.

Antigens, Bacterial↗
PubMed1989

N-terminal mutations activate the leukemogenic potential of the myristoylated form of c-abl.

The two major forms of the c-abl gene differ from their activated counterpart, the v-abl oncogene of the Abelson murine leukemia virus by the replacement of their N-terminal sequences with viral gag sequences. Overexpression of p150c-abl type IV in a retroviral vector similar to Abelson virus does not transform NIH 3T3 fibroblasts, even though it is expressed and myristoylated at levels comparable to pp160v-abl. Members of a nested set of deletion mutations of the N-terminus of c-abl type IV in this expression system will activate abl to transform murine fibroblasts. The smallest of these deletions, delta XB, efficiently transforms lymphoid cells in vitro and causes leukemia in vivo demonstrating that gag sequences are not necessary for abl-induced leukemogenesis. The delta XB mutation defines an N-terminal regulatory domain, which shares a surprising homology with chicken oncogene v-crk and phospholipase C-II. Although overexpression of the myristoylated form of c-abl does not transform cells, it nonetheless has a profound effect on cell growth.

Abelson murine leukemia virus↗
PubMed1989

Development and validation of a sensitive immunohistochemical oestrogen receptor assay for use on archival breast cancer tissue.

In a preliminary paper (Teasdale et al. 1987) comparing the oestrogen receptor (ER) content of breast cancers by the biochemical dextran coated charcoal (DCC) method and by two histochemical methods, peroxidase immunocytochemistry (ERICA) and immunogold-silver staining (IGSS), it was indicated that ERICA is more sensitive than DCC and that IGSS is as specific as ERICA but less sensitive. This paper describes the comparison of the above three assay methods with two other biochemical methods, iso-electric focusing (IEF) and an enzyme immuno-assay (EIA) on a larger number of cancers. All methods gave statistically comparable results except that IGSS remained less sensitive than the rest. Various modifications to IGSS showed that an immunogold streptavidin enhancement method (IG-SAM) produced sensitivity and specificity equal to that of ERICA. Since IGSS and its modifications are the only methods which can be used on archival paraffin-embedded cancers and IG-SAM gives results highly comparable to ERICA, retrospective studies can be performed on patients whose outcome and response to various treatments are known. Most recent studies have shown that ER positive results can be obtained from 10-year-old paraffin blocks.

Antibodies, Monoclonal↗
PubMed1989

In situ hybridization technique using an immunogold silver staining system.

An in situ hybridization technique using an immunogold silver staining detection system was used to detect biotinylated DNA probes in cultured cells and in formalin-fixed paraffin-embedded tissue. The detection method is rapid, reliable and economical, producing an insoluble signal at the site of hybridization which is visible at low-power light microscopy and which can be enhanced by epipolarization microscopy.

Cell Line↗
PubMed1989

Chlordiazepoxide vs. methadone in opiate withdrawal: a preliminary double blind trial.

A double blind trial of chlordiazepoxide vs. methadone in the management of the opiate withdrawal syndrome was conducted in a group of 24 regular heroin takers. Subjective and objective measures including physiological parameters were recorded to compare the severity of opiate withdrawal between the two groups. No significant difference was found in terms of subjective withdrawal distress between the two treatment conditions, although there was a tendency to a return of withdrawal symptoms in the methadone group towards the end of treatment. A nurse rating scale demonstrated a significantly higher level of withdrawal signs in the chlordiazepoxide group on day 3. Physiological measures suggested that neither group experienced a severe withdrawal illness. A similar number in each group (37%) became completely drug free.

Adult↗
PubMed1989

Evaluation of high vaginal insemination at oocyte recovery in patients undergoing in vitro fertilization.

The value of high vaginal insemination at the time of oocyte recovery for in vitro fertilization (IVF) has been assessed. A previous study reported a dramatic increase in the incidence of pregnancy in women after high vaginal insemination (53%) compared with those without insemination (23%). Of 306 patients undergoing IVF, 97 (32%) became pregnant and 20 (21%) miscarried. Those patients with tubal damage numbered 187. Sixty (33%) became pregnant and 10 (17%) miscarried. The data were assessed according to the numbers of conceptuses replaced, the age of the patient, and whether a spontaneous luteinzing hormone surge or human chorionic gonadotropin was a trigger for ovulation, each with a significant effect on the outcome of treatment. No significant effect of the use of high vaginal insemination was found.

Abortion, Spontaneous↗
PubMed1989

Identification of a talin binding site in the cytoskeletal protein vinculin.

Binding of the cytoskeletal protein vinculin to talin is one of a number of interactions involved in linking F-actin to cell-matrix junctions. To identify the talin binding domain in vinculin, we expressed the NH2-terminal region of the molecule encoded by two closely similar, but distinct vinculin cDNAs, using an in vitro transcription translation system. The 5' Eco RI-Bam HI fragment of a partial 2.89-kb vinculin cDNA encodes a 45-kD polypeptide containing the first 398 amino acids of the molecule. The equivalent restriction enzyme fragment of a second vinculin cDNA (cVin5) lacks nucleotides 746-867, and encodes a 41-kD polypeptide missing amino acids 167-207. The radiolabeled 45-kD vinculin polypeptide bound to microtiter wells coated with talin, but not BSA, and binding was inhibited by unlabeled vinculin. In contrast, the 41-kD vinculin polypeptide was devoid of talin binding activity. The role of residues 167-207 in talin binding was further analyzed by making a series of deletions spanning this region, each deletion of seven amino acids contiguous with the next. Loss of residues 167-173, 174-180, 181-187, 188-194, or 195-201 resulted in a marked reduction in talin binding activity, although loss of residues 202-208 had much less effect. When the 45-kD vinculin polypeptide was expressed in Cos cells, it localized to cell matrix junctions, whereas the 41-kD polypeptide, lacking residues 167-207, was unable to do so. Interestingly, some deletion mutants with reduced ability to bind talin in vitro, were still able to localize to cell matrix junctions.

Amino Acid Sequence↗
PubMed1989

Functions of the two adenovirus early E1A proteins and their conserved domains in cell cycle alteration, actin reorganization, and gene activation in rat cells.

Rat embryo cells were infected with adenovirus type 5 mutants that code for only one of the two early E1A proteins, mutants with defects in one of the two conserved regions common to the two proteins, or mutants with defects in the 46-amino-acid region unique to the 289-amino-acid E1A protein. Cells were scored for altered cell cycle progression, disruption of actin stress fibers, and activation of E2A expression. Mutants lacking either E1A protein were able to cause all of these effects; but mutants lacking a 243-amino-acid protein had less effect, and mutants lacking a 289-amino-acid protein much less effect, than wild-type virus. A mutation in any of the three conserved regions caused a defect in each E1A effect. To investigate the reported function of conserved domain 2 in mitosis, we monitored by fluorescence-activated cell sorter the reduction in Hoechst 33342 fluorescence that occurs when cells divide after undergoing a round of DNA replication in 5-bromodeoxyuridine. A smaller percentage of adenovirus-infected cells than mock-infected cells divided within a given period after completing a round of DNA replication. Viruses with mutations in conserved domain 2 were defective for initiation of cellular DNA replication, as were all other E1A mutants we have examined, but had no specific defect in cell division compared with wild-type virus. Thus, although there may be some specialization of function between the two E1A proteins and between their conserved domains, it was not apparent in the aspects of E1A function and the mutants that we examined.

Actin Cytoskeleton↗
PubMed1989

Relationship between organization of the actin cytoskeleton and the cell cycle in normal and adenovirus-infected rat cells.

Flow cytometry and staining with 7-nitrobenz-2-oxa-1,3-diazole-phallacidin were used to investigate organization of the actin cytoskeleton in rat embryo cells at different stages of normal and adenovirus E1A-induced cell cycles. In uninfected cells in G0-G1 and S phases, actin was predominantly in the form of stress fibers. In G2, this organization changed to peripheral rings of thin filaments, while during mitosis, actin had a diffuse distribution. Infection of quiescent rat cells by adenovirus caused them to enter the cell cycle and replicate DNA and also caused disruption of stress fibers. Rapid disappearance of stress fibers and the appearance of peripheral rings of actin filaments began from 13 h after infection and closely followed synthesis of the E1A proteins. Infected cells began S phase at about 24 h after infection, and cells in G2 and mitosis were seen from 30 to 50 h. Thus, disruption of the actin cytoskeleton is an early effect of E1A and not an indirect consequence of the entry of infected cells into the cell cycle.

Actins↗
PubMed1989

Dietary treatment of hyperlysinaemia.

We describe the lysine restricted, dietary management of three out of four siblings who were identified as having hyperlysinaemia. The diets, started in the neonatal period, were maintained for varying periods with unpredictable success. The propositus, who was not treated, was diagnosed at the age of 5 years, by which time he was already severely handicapped, presumably because of his metabolic disorder. Tentative recommendations are put forward for the management of this seemingly rare disorder. Mild chronic ammonia toxicity may be a factor in the pathogenesis of this condition.

Amino Acid Metabolism, Inborn Errors↗
PubMed1989

Expression of a muscle-type alpha-actinin cDNA clone in non-muscle cells.

We have previously isolated a chick smooth muscle-type alpha-actinin cDNA clone (C17) from a chick embryo fibroblast cDNA library. As part of an investigation into a possible role for a muscle isoform of alpha-actinin in non-muscle cells, we have cloned C17 into a eucaryotic expression vector, pKCR3, and examined the distribution of the expressed protein in non-muscle, monkey COS cells. We report here that the muscle isoform of chick alpha-actinin encoded by C17, was found in focal contacts and periodically distributed along actin filaments.

Actinin↗
PubMed1988

Long-term use of nicotine chewing gum. Occurrence, determinants, and effect on weight gain.

Among 538 clients of a Smokers Clinic who were treated with 2-mg nicotine chewing gum, 34 (6.3%) were still using the gum at one-year follow-up. This group represented 25% of lapse-free abstainers. At one-year follow-up, long-term gum users were using an average of 6.8 pieces of gum per day. Long-term gum users were similar to treatment failures in cigarette consumption and tobacco dependence, while "gum-free" successes were significantly lighter and less-dependent smokers. Long-term gum users used more gum during the four weeks of treatment than treatment failures, who in turn used more than the gum-free successes. It is suggested that for many the long-term use of gum was an essential ingredient of their success. Long-term gum users gained significantly less weight than other long-term treatment successes.

Adult↗