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Biomedical subjects

M Harvey

Publications and source records attributed to M Harvey.

At least 127 records · Page 7Linked to original sources
PubMed1993

Direct isolation and expansion of human CD34+ hematopoietic stem cells.

The isolation and expansion of CD34+ cells has numerous applications as supportive therapy for cytopenias that occur postchemotherapy. In this report, we describe a simple system to directly isolate and culture human CD34+ cells. Using this system, CD34+ cells isolated from bone marrow were cultured in the presence of GM-CSF, G-CSF, erythropoietin, stem cell factor, IL-1, IL-3, and IL-6. Cell expansions up to 100-fold were noted during the first 2 weeks of culture with high maintenance of CD34+ cells during the first week of culture. Maximal expansions of progenitors were observed at one week of culture, with, on average, 20-fold increases in CFU-GM number. The results support the feasibility of CD34+ cell expansion for clinical application.

Antigens, CD↗
PubMed1993

Genetic background alters the spectrum of tumors that develop in p53-deficient mice.

Using gene targeting in embryonic stem cells, we have generated mice with one or two null p53 germ line alleles. Mice with both p53 alleles inactivated are developmentally normal but highly susceptible to the early development of spontaneous tumors. Initial studies were performed in mice with a mixed inbred genetic background (75% C57BL/6 and 25% 129/Sv) (Donehower et al., Nature (London) 356, 215-221, 1992). To study the effect of genetic background on tumorigenesis in p53-deficient mice, we have put the p53 null allele into a pure 129/Sv background and monitored tumor development. 129/Sv mice with two p53 null alleles developed tumors sooner than the mixed genetic background p53-deficient animals. The most frequently observed tumor in p53 null mice of both genetic backgrounds was a malignant lymphoma. Because the 129/Sv strain has a low incidence of lymphoma, the frequent occurrence of lymphomas in all p53 null mice suggests that this particular tumor type may be a direct result of p53 loss and not a result of a particular genetic background. In addition to malignant lymphomas, the 129/Sv p53-deficient mice showed an increased incidence of aggressive teratocarcinomas (8 of 18 tumor-bearing males), a tumor type rare in virtually all inbred mice except for 129 strains. Thus, it appears that loss of p53 may accelerate a prior tumor predisposition and that genetic background can play a role in mediating both the rate and spectrum of tumor development in these mice.

Animals↗
PubMed1993

Titration of power output during radiofrequency catheter ablation of atrioventricular nodal reentrant tachycardia.

Radiofrequency lesions in the anterior, superior aspect of the tricuspid annulus result in selective elimination of fast pathway function in patients with typical atrioventricular (AV) nodal reentry tachycardia. This technique is simple and effective, but has been associated with a significant risk of inadvertent complete AV block. The purpose of this study was to compare the safety and effectiveness of two different techniques for radiofrequency catheter ablation of the fast AV nodal pathway. Initially, a fixed power output was used at each target site. This method was compared retrospectively to a newer technique where power output was gradually incremented at each site. Radiofrequency power was initially applied at 10 watts for 10-15 seconds. If no junctional ectopy or a change in PR interval was seen, power output was incremented by 2 to 4 watts every 10 to 15 seconds up to a maximum of 30 watts. Thirty seven of 38 (96%) patients treated using this incremental power output were cured of their AV nodal reentry tachycardia. None of these patients developed inadvertent complete AV block. In contrast, 92% of historic controls treated with a fixed power output between 20 and 30 watts achieved a primary success and nine of these 89 (10%) historic controls developed inadvertent complete AV block (P = 0.04). There was no difference in the amplitudes of atrial, His, or ventricular electrograms at the effective sites between the two groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Atrioventricular Node↗
PubMed1993

Radiofrequency catheter ablation of ventricular tachycardia in patients with coronary artery disease.

BACKGROUND: Radiofrequency (RF) ablation of idiopathic ventricular tachycardia (VT) has been demonstrated to be highly efficacious, but the efficacy of RF ablation of VT in patients with coronary artery disease has been unknown. Therefore, the purpose of this study was to determine the feasibility of RF ablation of VT in patients with coronary artery disease. METHODS AND RESULTS: Fifteen consecutive patients with coronary artery disease and a history of myocardial infarction underwent an attempt at RF ablation of 16 hemodynamically stable monomorphic VTs that had been documented clinically on a 12-lead ECG and that had not been successfully managed by pharmacological or device therapy. One VT was incessant, five occurred more than 25 times, and the remainder occurred two to 20 times. An additional four VTs that had not been documented clinically also were targeted for ablation. The mean age of the patients was 68 +/- 7 years (+/- SD), and their mean left ventricular ejection fraction was 0.27 +/- 0.08. The mean cycle length of the 20 VTs targeted for ablation was 438 +/- 82 msec. Ablation sites were selected based on endocardial activation mapping, pace mapping, identification of an isolated mid-diastolic potential, or concealed entrainment. Sixteen of the 20 VTs (80%) were successfully ablated in 11 of 15 patients (73%), using a mean of 4.2 +/- 3 applications of RF energy, and no recurrences of the ablated VTs occurred during 9.1 +/- 3.3 months of follow-up. The mean duration of the ablation procedures was 128 +/- 30 minutes. No complications occurred in any of the patients. CONCLUSIONS: The results of this study demonstrate that RF ablation of hemodynamically stable VT is feasible as adjunctive therapy in selected patients with coronary artery disease.

Aged↗
PubMed1993

In vitro growth characteristics of embryo fibroblasts isolated from p53-deficient mice.

Fibroblast cultures were derived from mouse embryos containing either one (p53+/-) or two (p53-/-) inactivated p53 alleles and compared to normal embryo fibroblasts for a number of growth parameters. Early passage p53-deficient embryo fibroblasts (p53-/-) divided faster than normal embryo fibroblasts, achieved higher confluent densities, and had a higher fraction of division-competent cells under conditions of low cell density. Flow cytometry studies of early passage embryo fibroblasts showed that the percent of p53-deficient cells in G0/G1 was lower than in normal cells, consistent with the argument that p53 mediates a G1 block. When p53-deficient and normal cells were passaged for long periods of time, the homozygote (p53-/-) fibroblasts grew at a high rate for over 50 passages and never entered a non-growing senescent phase characteristic of the heterozygote (p53+/-) and normal (p53+/+) cells. The p53-deficient fibroblasts were genetically unstable during passaging, with the p53-/- cells showing a high degree of aneuploidy and the p53+/- cells displaying a moderate level of chromosomal abnormalities by passage 25. Surprisingly, the heterozygote cells lost their single wild type allele very early during culturing and in spite of this loss most heterozygote lines entered into senescence. We conclude that the loss of p53 by itself is insufficient to confer immortality on a cell, but does confer a growth advantage. Taken together, the findings confirm that the absence of p53 promotes genomic instability, which in turn may result in genetic alterations which directly produce immortality.

Animals↗
PubMed1993

Role of pre-admission clinics in a general surgical unit: a 6-month audit.

We report a 6-month audit of the running of a pre-admission assessment clinic for routine general surgical admissions. An attendance rate of 91.4% of fit patients ready for surgery on the day of admission was achieved. Of all patients attending the pre-admission clinics, 79.5% underwent surgery as planned. Pre-admission clinics are recommended as a method of improving the efficiency of elective surgical admissions.

Adolescent↗
PubMed1993

A simple apparatus for fast and inexpensive recovery of DNA from polyacrylamide gels.

A typical elution procedure for DNA should be easy, quick, inexpensive, highly efficient and must provide DNA of good purity and quality to carry out any further enzymatic reactions. Although a number of procedures and apparatus for the specific isolation of DNA from polyacrylamide gels have been described, none possess all these qualities. In this report, we describe the use of a simple apparatus with which DNA molecules can be eluted from polyacrylamide gels with a recovery efficiency of about 90% prior to ethanol precipitation. The quality of these elution products is good enough to allow their use in any further enzymatic reactions. In addition to the fact that more than a dozen individual samples can be eluted and isolated in less than two hours (less than one hour for a single sample), the estimated low cost per electroeluted sample makes it the most affordable and economical elution method available.

Base Sequence↗
PubMed1992

Dbp73D, a Drosophila gene expressed in ovary, encodes a novel D-E-A-D box protein.

Proteins of the D-E-A-D family of putative ATP-dependent RNA helicases have been implicated in translation initiation and RNA splicing in a variety of organisms from E. coli to man. The Drosophila vasa protein, a member of this family, is required in the female germ line for fertility and for specification of germ line and posterior positional information in progeny embryos. We report the isolation of another D-E-A-D gene from Drosophila, which, like vasa, is expressed in germ line tissue. The predicted amino acid sequence of this new gene, Dbp73D, contains all of the highly conserved helicase motifs, but is otherwise the farthest-diverged member of the family so far identified.

Amino Acid Sequence↗
PubMed1992

Mice deficient for p53 are developmentally normal but susceptible to spontaneous tumours.

Mutations in the p53 tumour-suppressor gene are the most frequently observed genetic lesions in human cancers. To investigate the role of the p53 gene in mammalian development and tumorigenesis, a null mutation was introduced into the gene by homologous recombination in murine embryonic stem cells. Mice homozygous for the null allele appear normal but are prone to the spontaneous development of a variety of neoplasms by 6 months of age. These observations indicate that a normal p53 gene is dispensable for embryonic development, that its absence predisposes the animal to neoplastic disease, and that an oncogenic mutant form of p53 is not obligatory for the genesis of many types of tumours.

Alleles↗
PubMed1992

Factors associated with successful vocational rehabilitation in persons with arthritis.

OBJECTIVE: The objective of this study was to analyze factors associated with successful vocational rehabilitation (return to work) among persons receiving state-federal vocational rehabilitation services because of work disability from arthritis. METHODS: Multivariate analyses were used to determine the association of sociodemographic, disease-related, and agency factors with work outcome among a group of 456 persons with arthritis receiving state-federal vocational rehabilitation services during 1985-1988. RESULTS: Agency-sponsored physical restoration services (P less than 0.0001) and retraining (P less than 0.0001) were the variables most strongly correlated with return to work. Age, sex, race, disease severity, financial status, and educational level assessed at intake were not significantly associated with work rehabilitation outcome. CONCLUSION: Factors potentially amenable to agency intervention were more strongly associated with work rehabilitation outcome than were sociodemographic or disease-related variables.

Adult↗
PubMed1992

Impedance monitoring during radiofrequency catheter ablation in humans.

Radiofrequency catheter ablation of accessory pathways and the atrioventricular junction often requires multiple applications of energy. The inability to determine the effects of any given application on the underlying tissue may contribute to this problem. In the present study, impedance was monitored in 20 patients undergoing radiofrequency catheter ablation, and the relationship between an initial decrease in impedance and subsequent effects were examined. An initial fall in impedance of more than 10 omega was 78% sensitive and 88% specific for predicting subsequent evidence of tissue heating (interruption of conduction or an abrupt rise in impedance due to coagulum formation). In contrast, initial values of voltage, current, or impedance did not distinguish between effective and ineffective applications of radiofrequency energy. Continuous monitoring of impedance may facilitate radiofrequency catheter ablation.

Adult↗
PubMed1992

Transcription of the mouse secretory protease inhibitor p12 gene is activated by the developmentally regulated positive transcription factor Sp1.

We have previously shown that a trans-acting protein produced in some tissue culture cells positively control the transcriptional activity directed by the mouse p12 promoter. This nuclear protein exerts its positive activity by interacting with a regulatory sequence designated p12.A and located between the TATA and CCAAT box elements on the p12 gene promoter. Using DNase I and dimethyl sulfate methylation interference footprinting techniques coupled with gel retardation assays, we found evidence that the protein which binds to the p12.A element is the well-known transcription factor Sp1. Mutational analysis in transient transfection assays confirmed the positive activity exerted by this protein in every cell line tested. In agreement with this observation, we detected a p12.A-Sp1 binding activity in nuclear extracts prepared from all cell lines used. However, a similar binding activity could not be detected in a number of nuclear extracts prepared from normal mouse tissues. In this report, we provide the evidence that the lack of Sp1-binding activity results from the degradation of Sp1 in the kidney, liver, and pancreas of the mouse.

Animals↗
PubMed1992

Expression of cauliflower mosaic virus ORF II in a baculovirus system.

The cauliflower mosaic virus ORF II encoding the aphid transmission factor (ATF) was mutagenized to introduce a BamHI restriction site upstream from the initiation codon and then cloned into an eukaryotic viral expression vector (Autographa californica nuclear polyhedrosis virus). All recombinant viruses tested in Spodoptera frugiperda (SF21) cells expressed a protein of about 18 kD which comigrated in PAGE with ATF from infected plants. Western blotting using an oligopeptide antiserum to ATF confirmed the identity of the 18-kD protein from infected cells as the product of the ORF II sequences (P18). Subcellular fractionation of cells infected with the recombinant AcMNPV demonstrated that the expressed P18 accumulated intracellularly in an insoluble form. Antiserum was produced in rabbit against the partially purified P18 expressed in SF21 cells. When used to immunogold label ultrathin sections of cauliflower mosaic virus (CaMV)-infected turnip tissue, this antiserum was shown to be highly specific, labelling only the electronlucent inclusion bodies (containing P18) and not other plant cellular components.

Animals↗
PubMed1992

Isolation of temperature-sensitive diphtheria toxins in yeast and their effects on Drosophila cells.

We have isolated temperature-sensitive diphtheria toxins (DT-A(ts)) to develop a method that allows temporal impedement of cellular functions. Four DT-A(ts) genes were isolated in a mutagenesis screen using the yeast, Saccharomyces cerevisiae. When expressed in yeast, these DT-A(ts) arrest growth at 18 degrees C but not at 30 degrees C. Three DT-A(ts) were subsequently tested in the R1-R6 photoreceptor cells of transgenic fruit flies, Drosophila melanogaster. The toxins show similar temperature dependence in both organisms, suggesting that they may be useful in a wide range of non-homeothermic species. DNA sequence analysis revealed that three of the four DT-A(ts) mutations are novel. Interestingly, the fourth DT-A(ts) carries the same point mutation as the extensively characterized CRM197, an ADP ribosyltransferase-defective form of diphtheria toxin.

Animals↗
PubMed1991

Homelessness as psychological trauma. Broadening perspectives.

Most mental health literature on homelessness has focused on characteristics that may be risk factors for homelessness. The authors of this article argue that homelessness itself is a risk factor for emotional disorder and use the construct of psychological trauma--focusing on social disaffiliation and learned helplessness--to understand the potential effects of homelessness. Psychological trauma is likely among homeless individuals and families for three reasons. (a) The sudden or gradual loss of one's home can be a stressor of sufficient severity to produce symptoms of psychological trauma. (b) The conditions of shelter life may produce trauma symptoms. (c) Many homeless people--particularly women--become homeless after experiencing physical and sexual abuse and consequent psychological trauma. Research suggests that negative psychological responses to traumatic events can be prevented or mitigated by a supportive and empowering posttrauma environment. The implications of trauma theory for improving the psychosocial conditions of homeless people are discussed.

Adaptation, Psychological↗
PubMed1990

An evaluation of a community based antismoking campaign.

The short and long term effectiveness of a community based antismoking campaign (The Levin Smoke-Free Fun Week: 2-9 November 1985) was evaluated by three surveys of Levin residents (n = 511). The first survey, carried out one week after the campaign ended, found that 29.1% of Levin smokers attempted to reduce tobacco consumption in response to the campaign. Of the total smoking sample (n = 134), 4.4% quit altogether, 10.4% quit for part of the week, while 12.6% reduced their consumption or changed to low tar cigarettes. A follow up survey conducted three months later found a reduced, but still sizeable, proportion of the smokers (14.8%) maintaining those original benefits. Four point four percent were found to be still not smoking, while 10.4% were found to have reduced the number of cigarettes they consumed per day compared to their precampaign level. Seven point four percent had reverted to their previous level, while 2.2% had increased their consumption. A final survey carried out one year after the campaign found that 17.9% of smokers had either given up smoking for good or had reduced their cigarette consumption. Of the total sample, 8.2% had quit smoking, while 9.7% had reduced their consumption. Two point two percent had maintained their precampaign level, while 2.9% had increased their consumption. Measures taken of average cigarette consumption over the three surveys found an overall drop from 15.7 per day before the campaign, to 8.8 per day, one year after the campaign ended.

Adolescent↗
PubMed1990

Bromfenac, acetaminophen, and placebo in orthopedic postoperative pain.

In a double-blind, placebo-controlled, single-dose, parallel-group study, oral doses (5, 10 and 25 mg) of the prostaglandin synthetase inhibitor bromfenac were compared with acetaminophen (1000 mg) and placebo for postoperative orthopedic pain. Analgesic measurements were made by nurse observers by use of standard verbal rating and visual analog scales. For most pain intensity and pain relief measurements, 1000 mg acetaminophen was statistically superior to placebo, demonstrating assay sensitivity, and 10 and 25 mg doses of bromfenac were statistically better than both placebo and 5 mg bromfenac for ordinal and analog ratings of pain intensity and pain relief; 25 mg bromfenac produced significantly longer time to remedication than acetaminophen. The 5 mg dose of bromfenac was statistically superior to placebo for some measures, including remedication time. There were no untoward adverse effects or alterations in vital signs. Overall, 10 mg bromfenac produced analgesia equivalent to that of 1000 mg acetaminophen in this pain context.

Acetaminophen↗