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Biomedical subjects

M Price

Publications and source records attributed to M Price.

At least 73 records · Page 4Linked to original sources
PubMed1993

Multipartite nature of potato virus X.

Potato virus X (PVX) was among the first viruses to be purified. Nonetheless, properties of the purified virus remain contentious. The literature has been heavily influenced by the concept of a virus as a monopartite entity. Despite the fact that electron micrographs invariably show large proportions of shorter virus particles, the latter are universally ignored. Seven distinct classes of particle lengths were detected. Seven RNA species of approximate sizes 6.4, 3.6, 3.0, 2.1, 1.8, 1.4, and 0.9 kb were extracted from these purified virus preparations. This study shows clearly that shorter PVX particles are not breakage products and indicates that they may reflect fundamental properties of the genome strategy. Furthermore, other potexviruses have been found to contain many shorter particles, and the level of these particles is stable during purification. PVX is generally believed to consist of particles of single length even though the literature does not confirm this conclusion. The notion of a single particle length appears to reflect historical concepts of what a virus should be rather than what PVX is. This report considers whether shorter rods present in virus preparations of PVX are distinctive products of infection. The problem addressed is significant because if affects conclusions concerning the mechanisms of PVX biosynthesis and replication.

Blotting, Northern↗
PubMed1993

The impact of incest on identity formation in women.

In conclusion, the purpose of this paper was to elucidate some of the long-term impacts of the incest trauma on women. This includes its impact on identity formation. The process of idealization and the creation of an idealized image as a defensive and adaptive strategy to cope with overwhelming trauma was highlighted. This initially successful coping mechanism later causes problems in limiting the individual's self-perception and restricting her relationships with others. This is frequently manifested in problems that the adult survivor presents in regard to interpersonal relationships, as well as revictimization and an inhibition in identifying and expressing certain aspects of herself. The goal of treatment is therefore twofold. I am in agreement with Alpert (1991), van der Kolk (1987), and others who stress the importance of the validation and integration of the trauma and related affects through the recovery and reliving of past memories. Additionally, an analysis of the character structure that the person developed to cope with overwhelming and damaging experiences is essential. The achievement of a more cohesive, integrated sense of self for an adult survivor of incest can only be accomplished through the working through of past traumas and the understanding of its effect on identity development and character structure. This aspect of the treatment process was best expressed by one of my patients, who said, "the first part of my analysis dealt with remembering and reliving what happened to me, the second part is dealing with who I had to become and not become as a result of it." She later added that she felt the second part is even more difficult and challenging.

Adolescent↗
PubMed1993

Metals and the skin.

Certain metals, and many metal-based compounds, are inherently toxic, and their presence in occupational and environmental settings raises appropriate questions concerning human exposure. Contact of these materials with the skin represents an important route of exposure, which is not well characterized. The purpose of this review, therefore, is to assemble the available, useful information pertinent to risk assessment following dermal contact. Specifically, we summarize here: (1) data relevant to the qualitative and (where possible) quantitative evaluation of metal compound permeation through the skin; (2) the role of each metal in metabolism, particularly with respect to the skin, and the potentially toxic effects that may result from dermal contact; and (3) the immunological characteristics (including allergenicity) of the metals and their derivatives. In total, information on 31 metals has been reviewed. It is clear that many diverse factors determine the ability of metal-based species to permeate biological membranes, not all of which have been fully defined. Therefore, considerably more experimentation, targeted at the development of high-quality transport data, will be required before the specification of practically useful structure-activity relationships are possible.

Animals↗
PubMed1993

Neuroprotectants in Honghua: glucose attenuates retinal ischemic damage.

PURPOSE: This study examined the neuroprotective properties of Honghua, an extract of safflower used as an herbal medicine in China, in several experimental models of retinal ischemia. METHODS: Honghua and other agents were tested (1) in the ex vivo chick embryo retina assay (CER) for anti-excitotoxin efficacy and against simulated ischemia (30 min glucose/oxygen deprivation); and (2) in the in vivo adult rat retina dye-photothrombosis assay. Active components of Honghua were purified by conventional chromatographic techniques. RESULTS: In the CER, Honghua protected against excitotoxicity of glutamate, N-methyl-D-aspartate, kainate, and quisqualate, and against neuronal degeneration caused by simulated ischemia. Honghua more potently protected against simulated ischemia than against the agonists. In the in vivo adult rat retina, ischemic damage was reduced greatly by intravitreal injection of Honghua. An approximately 100-fold purification of an active principle was achieved chromatographically. The purest fractions were rich in glucose, so the effects of glucose in the ischemia models were determined. Many neuroprotective effects of Honghua were mimicked by pure solutions of equivalent glucose concentration. Glucose (> 3.2 mmol/l) in the CER-ischemia assay provided protection. Glucose did not protect against the lesions induced by direct application of the excitotoxic agonists. Intravitreal injection of glucose provided highly significant neuroprotection in the adult rat retina dye-photothrombosis model. CONCLUSIONS: These results suggest that retinal excitotoxic damage in vivo can occur secondary to depletion of cellular energy reserves, and therefore may be prevented by simple procedures that maintain the availability of energy sources.

Animals↗
PubMed1992

Effect of diet on posttransplant hyperlipidaemia.

Twenty-five patients with a renal transplant for 15 months to 19.4 years, hyperlipidaemia and stable graft function underwent three months of dietary management. Plasma lipid and apolipoprotein concentrations and lipoprotein electrophoresis were measured after a 12 hour fast at enrollment and after three months of diet. The aims of diet were to reduce energy intake in the overweight, restrict fat to 25-30% of total intake, reduce saturated fat content to less than 10% of total energy and cholesterol to less than 300 mg/d. After three months of diet there was a significant fall in mean cholesterol/HDL cholesterol risk ratio and a rise in mean HDL cholesterol concentration. Six patients reverted to a normal lipoprotein electrophoretic pattern with a significant reduction in mean total cholesterol, LDL cholesterol, cholesterol/HDL cholesterol ratio, apoprotein B and apoB/apo A-1 ratio. Most of the other patients who made dietary modifications showed some improvement in their lipid parameters. Dietary modification should be the initial approach to the management of posttransplant hyperlipidaemia.

Adult↗
PubMed1992

Regional expression of the homeobox gene Nkx-2.2 in the developing mammalian forebrain.

A novel mouse homeobox-containing gene, Nkx-2.2, has been isolated. Nkx-2.2 is a member of a family of genes whose homeodomains are homologous to that of the Drosophila NK-2 gene. Nkx-2.2 transcripts are found in localized domains of the brain during mouse embryogenesis. Nkx-2.2 expression in the brain abuts and partially overlaps with the expression domains of two other related homeobox-containing genes, TTF-1 and Dlx. The expression domains of the three genes in the developing prosencephalon coincide with anatomical boundaries, particularly apparent in the diencephalon. This result raises the possibility that these genes may specify regional differentiation of the developing diencephalon into its anatomically and functionally defined subregions. Nkx-2.2 may be involved in specifying diencephalic neuromeric boundaries.

Animals↗
PubMed1992

Ecological effects of short-term ciprofloxacin treatment of travellers' diarrhoea.

Forty-two subjects travelling to Mexico for 11 days were enrolled in a randomized, double-blind, placebo-controlled trial comparing ciprofloxacin 250 mg twice daily for three days or placebo for treatment of travellers' diarrhoea. Seventeen (41%) subjects were randomized to treatment. By the last treatment day, all seven evaluable subjects in the ciprofloxacin group, and three of eight evaluable subjects in the placebo group were cured (P = 0.04). The mean time to cure was 26 h for ciprofloxacin and 60 h for placebo-treated patients (P = 0.03). Faecal specimen were collected pre-travel, after four days in Mexico, 48 h post-travel and four weeks post-travel. Potentially pathogenic Escherichia coli strains carrying diarrhoeagenic virulence genes were detected by DNA hybridization tests, during or after travel, in 41% of treated and 31% of asymptomatic travellers. Travel, irrespective of diarrhoea and type of treatment, had a minor impact on the aerobic and anaerobic microflora. In travellers with ongoing diarrhoea, a suppression of the numbers of anaerobic bacteria was found, but the microflora was otherwise virtually unaffected. Significantly increased frequencies of E. coli resistant to ampicillin, doxycycline, chloramphenicol and co-trimoxazole were found during and after travel in all categories of travellers, though more frequently in subjects who experienced diarrhoea. The susceptibility of Bacteroides spp. remained unchanged. The sensitivity of E. coli to ciprofloxacin was not affected by travel, except in four ciprofloxacin-treated subjects who acquired multiresistant E. coli with ciprofloxacin MICs of > or = 0.125 mg/L post-travel. Bacteroides strains with MICs of > or = 64 mg/L were isolated post-travel from four ciprofloxacin-treated patients, and from one of the other 34 travellers not treated with ciprofloxacin.

Administration, Oral↗
PubMed1992

Human lumbar vertebrae. Quantitative three-dimensional anatomy.

This study details the quantitative three-dimensional surface anatomy of human lumbar vertebrae based on a study of 60 vertebrae. The two lower vertebrae (L4 and L5) appeared to be transitional toward the sacral region, whereas the upper two vertebrae (L1 and L2) were transitional toward the thoracic region. Means and standard errors of the means for linear, angular, and area dimensions of vertebral bodies, spinal canal, pedicle, pars interarticularis, spinous and transverse processes were obtained for all lumbar vertebrae. This information provides a better understanding of the spine, and allows for a more precise clinical diagnosis and surgical management of spinal problems. The information is also necessary for constructing accurate mathematical models of the human spine.

Cadaver↗
PubMed1992

Expression of the murine Dlx-1 homeobox gene during facial, ocular and limb development.

We have analysed the expression pattern of the mouse homeobox containing gene Dlx-1. This gene harbors a homeodomain related to that found in the Drosophila distal-less (dll) gene. In addition to its expression in the developing forebrain, Dlx-1 is transcribed in several structures containing cells of neural crest origin such as the facial mesenchyme and various elements of the peripheral nervous system. Dlx-1 transcripts are also detected in the differentiating retina and during limb morphogenesis, in the apical ectodermal ridge. The possible involvement of Dlx-1 during facial, ocular and limb development is discussed.

Animals↗
PubMed1992

Examination of potato virus X proteins synthesized in infected tobacco plants.

Nucleotide sequence analysis of potato virus X (PVX) genomic RNA predicts five open reading frames (ORFs). Previous analysis of total RNAs from PVX-infected leaf tissue suggested that six subgenomic RNAs are synthesized during infection. However, the proteins encoded by the genomic RNA, the subgenomic RNAs, or the predicted ORFs have not been identified in vivo. To characterize the coding properties of the viral RNA, particularly to determine whether the five predicted ORFs function in vivo, total protein extracts prepared from PVX-infected leaf tissue were analyzed by using antibodies raised against virus-specific synthetic peptides and against the virus capsid protein. Dot blot analyses showed that these antibodies reacted to PVX-infected extracts, indicating in vivo expression of the five predicted ORFs. In addition, Western blot (immunoblot) analysis of the extracts showed that ORF 1, 2, 3, and 4 peptide antisera and coat protein antiserum detect predominantly a single protein.

Amino Acid Sequence↗
PubMed1992

Cell-type-specific expression of the rat thyroperoxidase promoter indicates common mechanisms for thyroid-specific gene expression.

A 420-bp fragment from the 5' end of the rat thyroperoxidase (TPO) gene was fused to a luciferase reporter and shown to direct cell-type-specific expression when transfected into rat thyroid FRTL-5 cells. Analysis of this DNA fragment revealed four regions of the promoter which interact with DNA-binding proteins present in FRTL-5 cells. Mutation of the DNA sequence within any of these regions reduced TPO promoter activity. The trans-acting factors binding to these sequences were compared with thyroid transcription factor 1 (TTF-1) and TTF-2, previously identified as transcriptional activators of another thyroid-specific gene, the thyroglobulin (Tg) gene. Purified TTF-1 binds to three regions of TPO which are protected by FRTL-5 proteins. Two of the binding sites overlap with recognition sites for other DNA-binding proteins. One TTF-1 site can also bind a protein (UFB) present in the nuclei of both expressing and nonexpressing cells. TTF-1 binding to the proximal region overlaps with that for a novel protein present in FRTL-5 cells which can also recognize the promoter-proximal region of Tg. Using a combination of techniques, the factor binding to the fourth TPO promoter site was shown to be TTF-2. We conclude, therefore, that the FRTL-5-specific expression of two thyroid restricted genes, encoding TPO and Tg, relies on a combination of the same trans-acting factors present in thyroid cells.

Animals↗
PubMed1991

A mouse gene related to Distal-less shows a restricted expression in the developing forebrain.

Many genes known to be involved in embryogenesis and morphogenesis of the fruitfly Drosophila melanogaster encode proteins with a highly conserved region of 60 amino acids called the homeodomain. Mammalian counterparts for most of these genes have been identified, including those homologous to the Drosophila homeotic genes or to genes such as evenskipped, engrailed or caudal. We have isolated a murine homeobox gene that encodes a homeodomain similar to that encoded by the Drosophila Distalless (Dll) gene. Dll has a crucial role in Drosophila limb morphogenesis, partially specifying pattern along the proximo-distal axis of the limb. The murine counterpart is expressed in a restricted region of the developing brain, within the diencephalon and the adjacent telencephalic regions.

Amino Acid Sequence↗
PubMed1991

Characterization of high affinity binding sites for charybdotoxin in human T lymphocytes. Evidence for association with the voltage-gated K+ channel.

Charybdotoxin (ChTX) inhibits with high affinity a voltage-gated K+ channel that is present in human T lymphocytes. In this system, 125I-ChTX binds specifically and reversibly to a single class of sites which display a Kd of 8-14 pM, as measured by either equilibrium or kinetic binding protocols. The maximum density of sites, 542 sites/cell, correlates well with the density of K+ channel as determined by electrophysiological experiments. Binding of 125I-ChTX is modulated by the ionic strength of the incubation media and by Ca2+. Increasing concentrations of either K+, Na+, or Ca2+ cause inhibition of toxin binding. Inhibition of binding by Ca2+ is due, primarily, to an effect on toxin dissociation rates. Increasing the pH of the external media from 6.8 to 8.5 enhances toxin binding, due to an increase in affinity with no significant effect on the maximum density of receptor sites. Different agents that block the voltage-gated K+ channel in human T lymphocytes, inhibit toxin binding. Mitogen-stimulated T cells display 2.5-3-fold increase in toxin binding as compared with unstimulated control cells. These data, taken together, suggest that 125I-ChTX binding sites identified in this study, represent the predominant voltage-gated K+ channel present in peripheral human T lymphocytes. Therefore, 125I-ChTX is a useful probe for elucidating the physiological role of this type of K+ channel.

Binding Sites↗