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Biomedical subjects

D Murphy

Publications and source records attributed to D Murphy.

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

Muscarinic antagonists are anxiogenic in rats tested in the black-white box.

Central cholinergic (ACh) projections have been shown to modulate stress-induced activation of the hypothalamic-pituitary-adrenal (HPA) axis and are integral to the expression of electrophysiological correlates of arousal, namely hippocampal theta rhythm. The degree to which these actions of ACh are behaviorally relevant has received comparatively less attention, and we sought to investigate if manipulations of ACh systems might also affect behaviors related to stress and arousal. We chose to examine indices of anxiety as revealed by changes in behavior elicited by the black-white box test, a relatively novel and recently validated model of rodent anxiety. Groups of rats were injected with either scopolamine hydrobromide (SCOP; 0, 0.05, and 0.10 mg/kg i.p.) or the peripherally acting scopolamine methyl bromide (methyl-SCOP; 0, 0.05, and 0.10 mg/kg i.p.) to compare and contrast the effects of central and peripheral ACh blockade on measures of anxiety. SCOP pretreatment significantly lowered latencies for rats to escape from the white to black compartment, while methyl-SCOP elevated latencies to reenter the white chamber from the black. Both drugs increased the amount of time rats spent in the black compartment and also suppressed exploration as revealed by decreased episodes of intercompartmental locomotion. Neither drug deleteriously affected locomotor activity, however; in fact, SCOP significantly increased locomotion in the white chamber. In the absence of motor disturbances to account for any group differences, we contend that both central and peripheral ACh blockade may affect measures of anxiety, perhaps by directly or indirectly affecting HPA activity. Central ACh systems may underlie sensory filtering whereby irrelevant stimuli are excluded from sensory processing. Antagonism of ACh transmission may render an animal incapable of correctly processing sensory information leading to hyperresponsiveness, which can manifest itself as enhanced anxiety and fear.

Animals↗
PubMed1996

Ectopic vasopressin expression in MMTV-v-Ha-ras transgenic mice delays the onset of mammary tumorigenesis.

Neuropeptides are often ectopically expressed by non-endocrine tumours. We used transgenic mice to assess the effect of ectopic expression of the neuropeptide, vasopressin, in mammary tumours induced by the transgenetic expression of an activated ras oncogene. Mice bearing a mouse mammary tumour virus-vasopressin (MMTV-VP) fusion transgene synthesise authentic VP in mammary ducts and alveoli. Bitransgenic mice bearing both MMTV-VP and MMTV-v-Ha-ras transgenes developed tumours that were histologically indistinguishable from those of single MMTV-v-Ha-ras animals. However, tumour onset was significantly delayed in the bitransgenic animals. These data provide evidence that an ectopic neuropeptide can slow the development of ras tumours in vivo.

Animals↗
PubMed1996

Laparoscopic management of generalized peritonitis due to perforated colonic diverticula.

PURPOSE: The use of laparoscopic peritoneal lavage in conjunction with parenteral fluids and antibiotic therapy in the management of generalized peritonitis secondary to perforated diverticular disease of the colon was assessed. PATIENTS AND METHODS: This cohort comprised 8 patients with generalized peritonitis secondary to perforated diverticular disease of the left colon that was diagnosed laparoscopically. All the patients had purulent peritonitis, but no fecal contamination. They were treated with laparoscopic peritoneal lavage and intravenous fluids and antibiotics. RESULTS: All patients made a complete recovery, with resumption of normal diet within 5 to 8 days. No patient has required surgical intervention during a 12- to 48-month follow-up. This approach merits further assessment as an alternative to the traditional open surgical management.

Adult↗
PubMed1996

RNAs encoded by a 3.5-kb bovine vasopressin gene construct are targeted to the neurohypophysis of transgenic mice.

Recent studies have established that the RNA coding for the neuropeptide arginine-vasopressin (AVP) is expressed in the neurohypophyseal compartment of the hypothalamo-neurohypophyseal system. In order to determine the molecular mechanisms that direct this novel expression pattern we have now investigated whether an AVP transgene is similarly regulated. Using a reverse transcriptase-polymerase chain reaction (RT-PCR) approach that permits simultaneous analysis of both endogenous and transgene RNA levels, we have demonstrated that RNA derived from a 3.5-kb bovine vasopressin transgene is expressed in the neurohypophysis of transgenic mice, and is up-regulated by a physiological stimulus (salt-loading) in a similar manner to mouse AVP RNA. Sequences conserved between this region of the murine and bovine AVP genes are therefore sufficient to mediate neurohypophyseal expression. These lines of transgenic mice will serve as a model for the delineation of sequences that target expression beyond the neuronal perikaryon.

Animals↗
PubMed1996

Benzodiazepine receptor stimulation blocks scopolamine-induced learning impairments in a water maze task.

Central cholinergic (ACh) blockade produces profound cognitive impairments in human and animal subjects. Our previous research demonstrated that ACh blockade exacerbates stress-induced adrenocorticotrophin (ACTH) and corticosterone (CORT) secretion, and increases anxiety-like behavior (ALB) in rats. The fact that all these responses occur following the same manipulation led us to question whether or not increases in ALB might play a part in the cognitive deficits. This issue was all the more intriguing given that anxiolytic agents such as benzodiazepines are reported to produce learning and memory impairments on their own. We reasoned that a low dose of diazepam (DZP) with no apparent cognitive effects itself, might be able to antagonize an impairment induced by scopolamine (SCOP). Adult male Lister rats (n = 6/group) were administered IP either vehicle (VEH), 0.5 mg/kg DZP, 0.25 mg/kg SCOP, or 0.5 mg/kg DZP, followed 20 min later by 0.25 mg/kg SCOP, and tested 20 min later in a water maze for latency to locate a hidden platform and for path length taken to the platform. Rats were tested in an acquisition phase (Day 1) and a retention phase (Day 2), as well as on a visually guided task. On Day 1, SCOP produced a marked acquisition deficit that was unaffected by DZP. DZP by itself had no obvious effect. However, whereas SCOP resulted in a persistent deficit on the retention task (Day 2), pretreatment with DZP prior to SCOP on Day 1 completely abolished the impairment. There were no group differences on the visually cued task. We contend that SCOP-induced cognitive deficits may, in part, be due to increases in ALB. Stimulation of benzodiazepine receptors may offset the loss of cholinergic systems underlying consolidation mechanisms, but not those mediating immediate task performance. Whether this effect of DZP relates to an action on ALB remains to be elucidated.

Animals↗
PubMed1996

Antiepithelial cell antibodies do not impair paediatric renal allograft survival but appear to be associated with acute viral infections.

There is a reported association between antiepithelial cell (AEC) antibodies and increased renal allograft loss in paediatric recipients. Our unit experienced a dramatic fall in 1-year graft survival so we undertook a study to determine if AEC antibodies could account for such losses. We also studied healthy children and adults as well as a group of individuals with serologically proven viral infection in an attempt to determine the prevalence and possible aetiology of these antibodies. Sera were screened for AEC antibodies in a microcytotoxicity test using a lung epithelial cell line (A549) as target. The prevalence of these antibodies in our paediatric recipients was similar to that reported elsewhere but we found no correlation between the presence of AEC antibody and allograft loss. Within the control populations, we found the antibody was more prevalent in children than in adults (p < 0.0001). We also found a strong age banding pattern, with antibody being present in 50% of children under 10 years and declining with increasing age, so that by the age of 16 years the seroprevalence was similar to that found in our adults. However, AEC antibody had a significantly higher prevalence in individuals with active viral infection than in our healthy control groups (p = 0.00003). A positive association was noted between rubella and respiratory syncytial virus and AEC antibody presence and a negative association with varicella zoster. We conclude that AEC antibodies do not correlate with increased paediatric renal allograft loss but appear to be linked to certain viral infections.

Acute Disease↗
PubMed1996

Identification of a peptide methionine sulphoxide reductase gene in an oleosin promoter from Brassica napus.

A bidirectional promoter can be defined operationally as a short segment of DNA that regulates divergent transcription. In an attempt to investigate whether the intergenic region between the oleosin and a second open reading frame (ORFII) in Brassica napus (L.) is a divergent promoter, and also to characterize the ORFII, cDNA clones homologous to ORFII were isolated from a leaf cDNA library. A representative cDNA (clone D) of one of the two classes identified was identical, in DNA sequence, to the genomic ORFII. The second representative cDNA (clone O) was 97% identical at the nucleotide level to the genomic ORFII. The predicted amino acid sequence of the cDNA clones each exhibit homology with the peptide methionine sulphoxide reductase (PMSR) of Escherichia coli. The gene structure of ORFII was elucidated and the relative positions of the oleosin, ORFII, and the intergenic promoter region were determined. This confirms that the B. napus oleosin-ORFII intergenic region has divergent promoter activity. Consequently this is the first such plant nuclear divergent promoter identified. RFLP-mapping results showed that all four ORFII genes are linked to four of the six copies of the oleosin genes. This suggested that the bidirectional promoter locus is conserved within the B. napus genome. The ORFII gene product is targeted to the chloroplast, which is consistent with previous data indicating the presence of PMSR activity in the chloroplast. The over-expressed recombinant fusion protein (minus the transitpeptide) showed the capability to reduce peptide methionine sulphoxide residues in vitro, indicating PMSR activity. This study demonstrates that ORFII is transcribed and encodes a plant PMSR, and is the first example of the isolation of a eukaryotic PMSR gene.

Amino Acid Sequence↗
PubMed1996

Cloning, expression, and chromosomal localization of the rat mitochondrial capsule selenoprotein gene (MCS): the reading frame does not contain potential UGA selenocysteine codons.

The mitochondrial capsule selenoprotein (MCS) is a selenium-containing polypeptide. It is one of three proteins that are important for the maintenance and stabilization of the crescent structure of the sperm mitochondria. In this paper, we report the isolation and characterization of the rat MCS cDNA and gene. The cDNA contains a reading frame for a 145-amino-acid protein and it lacks the UGA codons, which have been found in the reading frame of the mouse MCS cDNA and have been presumed to encode the selenocysteine in the amino terminal of the deduced mouse amino acid sequence. The deduced amino acid sequence of the rat and mouse MCS shows a high level of homology (79%). The rat MCS gene contains two exons; the intron sequence interrupts the 5' untranslated sequence at the same position as in the mouse MCS gene. The transcription start site is located 184 bp upstream of the translation start site. Alignment of the 5'-flanking regions of the mouse and rat genes reveals that the first 400 nucleotides upstream of the transcription start site exhibit an overall sequence similarity of 73%. This conserved region contains no TATA or CAAT box motifs. Northern blot analysis indicates that the MCS mRNA is detectable only in the testis after day 30 of postnatal development. Moreover, in situ hybridization revealed that the rat MCS gene is mainly expressed in round spermatids. From the analysis of mouse-rat cell hybrids that segregate rat chromosomes, the MCS gene was assigned to rat chromosome 2.

Amino Acid Sequence↗
PubMed1996

The epidemiology of chest and leg wound infections following cardiothoracic surgery.

The occurrence of wound infections following cardiothoracic surgery has significant implications. However, the epidemiology of all chest and leg wound infections is infrequently described, and the effects on morbidity, mortality, and cost of care remain undefined. We identified 182 superficial and deep chest and leg infections in 163 patients following 1,554 coronary artery bypass graft (CABG), valve, and CABG/valve procedures over 30 months. The overall infection rate was 11.7%; infections of specific sites involved in the 1,554 procedures occurred at the following rates: 3.1%, superficial chest wounds; 2.3%, deep chest wounds; 4.6%, superficial leg wounds; and 2.2%, deep leg wounds. Chest infection rates were similar for all procedures. Multiple infections occurred in 9.8% of patients and were associated with female sex, diabetes, and prolonged surgery (P < .05). Purulent drainage and fever were more common in chest infections; erythema and pain were more common in leg infections (P < .05). Staphylococcus aureus (32.9%), coagulase-negative staphylococci (27.4%), and Enterobacteriaceae (26.0%) were identified most commonly. Enterobacteriaceae were more commonly isolated from leg wounds (P < .05). Adverse outcomes included reexploration (20.9%), flap surgery (12.3%), and death (4.3%). All adverse outcomes were more commonly associated with deep chest infections (P < .05), but superficial chest and leg infections also had a substantial impact on cardiothoracic surgery-related morbidity. Studies are needed to define site-specific risk factors so that the full potential of prevention and control measures can be realized.

Coronary Artery Bypass↗
PubMed1996

Nosocomial outbreak of gastroenteritis due to Salmonella senftenberg.

We describe a prolonged nosocomial outbreak of Salmonella senftenberg, an uncommon human pathogen. We detected 22 cases of infection due to S. senftenberg that occurred from March 1993 through November 1994 and involved 18 patients and four healthy employees. All infected persons had consumed food prepared by the hospital kitchen. The estimated attack rate for the period of the outbreak was 0.19-0.23 cases per 100,000 meals served. Infection control interventions included observation of food preparation, disinfection of kitchen devices, and education of food handlers. The consumption of lettuce (11 of 15 patients who could recount extended dietary histories vs. 4 of 20 controls; P = .005), cauliflower (5 of 15 vs. 0/20; P = .02), cottage cheese (4 of 15 vs. 0/20; P = .03), and deli turkey (8 of 15 vs. 0/20; P < .001) was associated with S. senftenberg infection. The isolates had identical antibiograms and pulsed-field gel electrophoretic patterns. Cultures of stool samples from food handlers as well as food items, kitchen devices, and kitchen surroundings were negative for S. senftenberg. Interruption of the outbreak occurred coincidentally with the institution of infection control measures. This prolonged outbreak of salmonellosis was probably related to contamination in the kitchen from turkey, with cross-contamination via equipment.

Adult↗
PubMed1996

CD4-IgG binding threshold for inactivation of human immunodeficiency virus type 1.

The stoichiometry of human immunodeficiency virus type 1 (HIV-1) inactivation by soluble receptor CD4-IgG hybrid dimers (CD4-IgG) was examined. The extent of HIV-1 inactivation was measured in a sensitive plaque-forming assay, and the corresponding level of CD4-IgG binding was determined by immunofluorescence of infected cells. Ninety percent virus inactivation occurred at relatively low levels of CD4-IgG binding (10% of the saturating level). At even lower binding levels (1.4% of maximum binding), virus survival was 44%. Over a broad range of binding conditions, the survival curve followed a model in which viruses binding more than a threshold level of CD4-IgG were completely inactivated, while viruses binding less remained infectious. The data indicate that CD4-IgG binding to 1.4% of gp120 binding sites equals the threshold for inactivation. Thus, virus inactivation can begin when 3 CD4-IgG (of approximately 216 gp120 sites) bind per virion.

Antigen-Antibody Reactions↗
PubMed1996

Are there genetic risks associated with microassisted reproduction?

Of all the techniques available for microassisted reproduction, the direct injection of individual sperm cells or spermatids into the cytoplasm of the oocyte (ICSI) is the most invasive, through which any possible selection against sperm cells with genomic defects would be excluded. It has, however, been shown that such a possible selection is present neither in the female genital tract nor at the zona pellucida. Selection against genetic-based defects occurs after the fertilization of the oocyte, during both embryonic and fetal development. Based on the data to date, it can be assumed that ICSI would not result in either a significant increase in genetic-based diseases, or in an increase in the number of infertile males. If, however, mutations of X-chromosomal or Y-chromosomal genes should play a major role in male fertility disorders, one could expect, over generations, an increase, though probably very slight, in the number of males with such disorders.

Animals↗
PubMed1996

Lycra working splint for the rheumatoid arthritic hand with MCP ulnar deviation.

Rheumatoid arthritis is described by Swanson (1995) as 'the greatest crippler from the standpoint of severity and prolonged disability' (p. 1307). One key factor in keeping persons with rheumatoid arthritis independent in their activities of daily living is maintaining functional use of their hands. In rural areas, where a move to assisted accommodation may require a person to leave the locality, this splint may help older citizens to remain functional and at home. The deformity and instability caused in rheumatoid arthritic hands by radial deviation of the wrist and subsequent ulnar deviation of the metacarpophalangeal (MCP) joints can greatly affect functional use of the hands. In this article, design and fabrication instructions for a lycra working splint which is suitable for the rheumatoid arthritic hand with MCP ulnar deviation are presented. Health professionals working in rural areas will find this splint inexpensive and easy to design, either alone or, ideally, with the assistance of regional occupational therapists.

Activities of Daily Living↗
PubMed1996

Detection of Mycobacterium tuberculosis in cerebrospinal fluid following immunomagnetic enrichment.

The detection of Mycobacterium tuberculosis by culture of cerebrospinal fluid (CSF) is unacceptably slow. Low numbers of organisms and the presence of reaction inhibitors may prevent detection of M. tuberculosis by PCR. We used immunomagnetic enrichment to accelerate and enhance the detection of mycobacteria in CSF after demonstrating the utility of the method with pure suspensions. Growth was detected earlier in Bactec cultures of magnetically recovered mycobacteria than in untreated CSF (7 versus 15 days). We detected M. tuberculosis DNA by PCR in the immunomagnetically enriched sample but not in untreated CSF. PCR fingerprintings of the immunomagnetically recovered M. tuberculosis and of the isolate subsequently recovered by culture were identical.

Adult↗
PubMed1996

Neurohypophyseal and fluid homeostasis in transgenic rats expressing a tagged rat vasopressin prepropeptide in hypothalamic neurons.

We have developed a transgenic system that, for the first time, facilitates monitoring of the regulatory dynamics of a central peptidergic system from transcription of a neuropeptide gene to the storage and release of the mature secretory product. A rat vasopressin (VP) transgene (5-VCAT-3), the expression of which is restricted to hypothalamic vasopressinergic magnocellular neurons in rats, contains a sequence that, if translated, would place a unique hexadecapeptide (DRSAGYYGLFKDRKEK, abbreviated to DR-12-EK) at the C-terminus of the VP precursor. We have raised an antibody against this "tag" and, using immunohistochemistry, electron microscopy, RIA, and HPLC, have shown for the first time that a VP transgene RNA is translated into a protein product found, in a processed form, in secretory granules in the posterior pituitaries of transgenic rats. Disruption of the C-terminus of the VP precursor by the peptide tag is well tolerated and does not disrupt VP production or disturb salt and water balance. An osmotic stimulus increased hypothalamic DR-12-EK levels, but changes in posterior pituitary DR-12-EK levels were more complex. After 5 days of salt-loading, DR-12-EK levels fell, as would be expected if its release was coordinate with that of VP. However, after 10 days of salt-loading, posterior pituitary DR-12-EK levels increased, despite the lower level of VP. This probably reflects the greater response of the transgene to osmotic challenge at the RNA level, increasing the proportion of DR-12-EK-containing translation products transported to the posterior pituitary relative to those derived from the endogenous gene. The exaggerated response of the tagged transgene to osmotic challenge at both RNA and protein levels affords a new opportunity to study the regulatory dynamics of the VP system at the molecular level, but within the physiologically advantageous context of the intact animal.

Amino Acid Sequence↗