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Biomedical subjects

S J Murphy

Publications and source records attributed to S J Murphy.

At least 19 recordsLinked to original sources
PubMed2004

Differential trafficking of transforming growth factor-beta receptors and ligand in polarized epithelial cells.

Epithelial cells in vivo form tight cell-cell associations that spatially separate distinct apical and basolateral domains. These domains provide discrete cellular processes essential for proper tissue and organ development. Using confocal imaging and selective plasma membrane domain activation, the type I and type II transforming growth factor-beta (TGFbeta) receptors were found to be localized specifically at the basolateral surfaces of polarized Madin-Darby canine kidney (MDCK) cells. Receptors concentrated predominantly at the lateral sites of cell-cell contact, adjacent to the gap junctional complex. Cytoplasmic domain truncations for each receptor resulted in the loss of specific lateral domain targeting and dispersion to both the apical and basal domains. Whereas receptors concentrate basolaterally in regions of direct cell-cell contact in nonpolarized MDCK cell monolayers, receptor staining was absent from areas of noncell contact. In contrast to the defined basolateral polarity observed for the TGFbeta receptor complex, TGFbeta ligand secretion was found to be from the apical surfaces. Confocal imaging of MDCK cells with an antibody to TGFbeta1 confirmed a predominant apical localization, with a stark absence at the basal membrane. These findings indicate that cell adhesion regulates the localization of TGFbeta receptors in polarized epithelial cultures and that the response to TGFbeta is dependent upon the spatial distribution and secretion of TGFbeta receptors and ligand, respectively.

Adherens Junctions↗
PubMed2003

Mortality in Barrett's oesophagus: results from a population based study.

BACKGROUND: Patients with Barrett's oesophagus have an increased risk of oesophageal adenocarcinoma but this cancer only accounts for a small proportion of deaths in these patients. Other causes of death are reportedly raised in this group. We examined cause specific mortality among individuals in a population based Barrett's oesophagus register. METHODS: We constructed a register of all patients diagnosed with columnar mucosa (including specialised intestinal metaplasia) of the oesophagus within Northern Ireland between 1993 and 1999. Deaths occurring within this cohort until 31 December 2000 were identified and mortality rates were compared with the general population. RESULTS: Overall mortality was not raised in Barrett's patients. During 7413 person years of follow up in 2373 patients there were 253 deaths (standardised mortality ratio (SMR) 96 (95% confidence interval (CI) 84-107)). Mortality from oesophageal cancer was raised in patients with specialised intestinal metaplasia (SMR 774 (95% CI 317-1231)) but only 4.7% of patients died from this cancer. Mortality from stroke (SMR 65 (95% CI 37-93)) was significantly lower than the general population while mortality from non-cancerous digestive system diseases was significantly higher (SMR 211 (95% CI 111-311)). Mortality rates from all other causes were similar to those of the general population. CONCLUSIONS: This study demonstrates that the overall mortality rate in patients with Barrett's oesophagus is closely similar to that of the general population. Oesophageal cancer mortality was raised but is an uncommon cause of death in these patients who also appear to have a reduced risk of death from stroke.

Adenocarcinoma↗
PubMed2001

The effect of brief halothane anesthesia during daily gavage on complications and body weight in rats.

We examined retrospectively the effects of brief halothane anesthesia during daily gavage administration of vehicle on gavage-related complications and body weight in ovariectomized female Wistar rats. The number of gavage-related deaths or animals requiring euthanasia due to gavage problems was dramatically reduced, but the occurrence of incomplete vehicle retention during gavage was increased appreciably in halothane-anesthetized animals. Halothane-anesthetized rats maintained daily body weight for a longer period than did awake animals. Our observations suggest that the use of brief inhalational anesthesia reduces gavage-associated death and euthanasia due to esophageal trauma and minimizes stress-related weight loss.

Anesthesia↗
PubMed2000

Neuroprotective effects of female gonadal steroids in reproductively senescent female rats.

BACKGROUND AND PURPOSE: Young adult female rats sustain smaller infarcts after experimental stroke than age-matched males. This sex difference in ischemic brain injury in young animals disappears after surgical ovariectomy and can be restored by estrogen replacement. We sought to determine whether ischemic brain injury continues to be smaller in middle-aged, reproductively senescent female rats compared with age-matched males and to test the effect of ovarian steroids on brain injury after experimental stroke in females. METHODS: Four groups of 16-month old Wistar rats (males [n=9], untreated females [n=9], and females pretreated with 17beta-estradiol [25-microgram pellets administered subcutaneously for 7 days; n=9] or progesterone [10-mg pellets administered subcutaneously for 7 days; n=9] were subjected to 2 hours of middle cerebral artery occlusion with the intraluminal filament technique, followed by 22 hours of reperfusion. Physiological variables and laser-Doppler cerebral cortical perfusion were monitored throughout ischemia and early reperfusion. In a separate cohort of males (n=3), untreated females (n=3), females pretreated with 17beta-estradiol (n=3), and females pretreated with progesterone (n=3), end-ischemic regional cerebral blood flow was measured by [(14)C]iodoantipyrine autoradiography. RESULTS: As predicted, infarct size was not different between middle-aged male and female rats. Cortical infarcts were 21+/-5% and 31+/-6% of ipsilateral cerebral cortex, and striatal infarcts were 44+/-7% and 43+/-5% of ipsilateral striatum in males and females, respectively. Both estrogen and progesterone reduced cortical infarct in reproductively senescent females (5+/-2% and 16+/-4% in estrogen- and progesterone-treated groups, respectively, compared with 31+/-6% in untreated group). Striatal infarct was smaller in the estrogen- but not in the progesterone-treated group. Relative change in laser-Doppler cerebral cortical perfusion from preischemic baseline and absolute end-ischemic regional cerebral blood flow were not affected by hormonal treatments. CONCLUSIONS: We conclude that the protection against ischemic brain injury found in young adult female rats disappears after reproductive senescence in middle-aged females and that ovarian hormones alleviate stroke injury in reproductively senescent female rats by a blood flow-independent mechanism. These findings support a role for hormone replacement therapy in stroke injury prevention in postmenopausal women.

Administration, Cutaneous↗
PubMed2000

LY353381.HCl, a selective estrogen receptor modulator, and experimental stroke.

BACKGROUND AND PURPOSE: The impact of postmenopausal estrogen replacement therapy on stroke prevention and stroke severity remains controversial. Previously we have shown that cerebral tissue infarction volume sustained after middle cerebral artery (MCA) occlusion is smaller in female than in male animals. This protection is lost after ovariectomy but is restored by 17ss-estradiol replacement. However, the therapeutic range for estradiol is suboptimal, since only doses resulting in a narrow range of plasma levels are protective in brain. The present study tested the hypothesis that a benzothiophene analogue and selective estrogen receptor modulator, LY353381.HCl (LY), reduces tissue infarction after MCA occlusion in estrogen-deficient, ovariectomized female rats. METHODS: Ovariectomized female Wistar rats received LY 10 mg/kg (n=16) or an equivalent volume of vehicle (n=14) by gavage for 5 to 8 days. Subsequently, each animal was anesthetized with halothane (1.2%) and treated with 2 hours of MCA occlusion by the intraluminal filament technique and 22 hours of recovery. Infarction volumes in the cerebral cortex and caudoputamen were determined by 2, 3,5-triphenyltetrazolium chloride staining and digital image analysis. End-ischemic regional cerebral blood flow (CBF) was measured in separate animal cohorts by quantitative [(14)C]iodoantipyrine autoradiography. RESULTS: Caudoputamen infarction was reduced by LY treatment (49+/-6% versus 64+/-4% of ipsilateral caudoputamen in LY and vehicle groups, respectively; P:<0.05). Cerebral cortical infarction was not different in the LY compared with vehicle group (7+/-3% versus 13+/-4% of ipsilateral cerebral cortex, respectively). Intra-ischemic blood pressure, arterial blood gases, and temporalis muscle temperature were controlled and equivalent between treatment groups. Averaged laser-Doppler flow during MCA occlusion was 36+/-3% of baseline in the LY group versus 29%+/-2% in the vehicle group. However, end-ischemic CBF or blood flow distribution within the MCA territory was not altered by LY treatment. Cortical or caudoputamen tissue volumes with end-ischemic CBF <20 mL/100 g per minute were similar in both groups. CONCLUSIONS: We conclude that LY confers neuroprotection from focal cerebral ischemia in caudoputamen in ovariectomized female rats. The mechanism of protection is not linked to preservation of ischemic cerebral blood flow, as determined by end-occlusion quantitative autoradiography.

Animals↗
PubMed2000

Progesterone exacerbates striatal stroke injury in progesterone-deficient female animals.

BACKGROUND AND PURPOSE: We have previously shown that female animals experience substantial protection from brain injury after reversible middle cerebral artery occlusion (MCAO) compared with their male or ovariectomized female counterparts. The reproductive steroid estrogen has been shown to provide neuroprotection from a variety of experimental insults, but the importance of progesterone as an anti-ischemic treatment has not been well explored. We evaluated histological outcomes after MCAO in ovariectomized female rats with or without acute or chronic progesterone replacement therapy. METHODS: Age-matched, adult female Wistar rats were ovariectomized and treated with 0, 30, or 60 mg/kg progesterone IP 30 minutes before ischemia (n=12 to 14 per group) or with 30 mg/kg progesterone IP daily for 7 to 10 days before ischemia (n=16). Each animal subsequently underwent 2 hours of MCAO with the intraluminal filament technique, followed by 22 hours of reperfusion. Ipsilateral parietal cortex perfusion was monitored with laser Doppler flowmetry throughout ischemia. Cortical, caudate-putamen, and hemispheric infarction volumes were determined with 2,3,5-triphenyltetrazolium chloride staining and digital image analysis. RESULTS: Intraischemic plasma progesterone levels were 5+/-3, 102+/-20,* 181+/-28,* and 133+/-25* ng/mL in the 0, 30, and 60 mg/kg acute progesterone group and the 30 mg/kg chronic progesterone group, respectively (*P<0.05 compared with 0 mg/kg). Caudate-putamen infarction volume (percent contralateral structure) was significantly increased by chronic progesterone treatment: 45.6+/-5.1%* in the 30 mg/kg chronic progesterone group and 29.2+/-5.3%, 35.8+/-5.1%, and 42.0+/-5.0% in the 0, 30, and 60 mg/kg acute progesterone groups, respectively (*P<0.05 compared with 0 mg/kg). Cortical and total hemispheric infarction volumes (percent contralateral structure) were unchanged by progesterone treatment. CONCLUSIONS: Exogenous progesterone therapy does not ameliorate histological injury after MCAO in previously ovariectomized, adult female rats. Furthermore, chronic progesterone administration can exacerbate infarction in subcortical regions.

Animals↗
PubMed2000

Hypertonic saline worsens infarct volume after transient focal ischemia in rats.

BACKGROUND AND PURPOSE: Hypertonic saline (HS) has been advocated as a hyperosmolar agent for the treatment of cerebral edema, especially after traumatic brain injury. We tested the hypothesis that continuous intravenous HS administered during reperfusion from transient focal cerebral ischemia attenuates infarct volume. METHODS: Halothane-anesthetized male Wistar rats were subjected to 2 hours of middle cerebral artery occlusion (MCAO) by the intraluminal occlusion technique. At the onset of reperfusion, rats received a 10-mL/kg intravenous bolus of 0.9% saline (SAL, n=8) or 7.5% SAL (chloride:acetate 50:50, n=8) followed by a continuous infusion for 22 hours. In a second series of experiments, ischemic damage was determined in cohorts treated with equivolumetric 3% saline (n=8) or 20% mannitol (n=8). In a third series, regional cerebral blood flow was measured ([(14)C]iodoantipyrine autoradiography) at 6 hours of reperfusion in 7.5%-SAL-treated (n=5) or SAL-treated (n=5) animals. RESULTS: In SAL rats, serum Na(+) was 137+/-3 and 138+/-2 mEq/L (mean+/-SEM) at baseline and 22 hours of reperfusion, respectively. In 7.5% SAL, serum Na(+) was 136+/-2 and 154+/-2 mEq/L at baseline and reperfusion, respectively. Physiological variables and reduction in laser-Doppler signal during MCAO and early reperfusion were not different between the 2 treatment groups. Cortical infarct volume was larger in 7.5%-SAL-treated rats (121+/-14 mm(3); 30+/-3% of contralateral cortex; P<0.05) than in SAL (64+/-15 mm(3); 16+/-4% of contralateral cortex). Striatal infarct volume was unchanged by HS therapy. Ipsilateral cortical tissue volume was increased relative to the contralateral side (by 26+/-5% with SAL; by 41+/-5% with 7.5% SAL). In contrast, ischemic damage was unaffected by 3%-SAL or 20%-mannitol treatment compared with SAL. Regional cerebral blood flow during reperfusion was heterogeneous in all animals, but there was no evidence of postischemic hypoperfusion or blood flow maldistribution in 7.5%-SAL-treated animals. CONCLUSIONS: These data demonstrate that hypernatremia resulting from postischemic HS infusion worsens cortical infarct volume in transient focal cerebral ischemia. The deleterious effect is not linked to exacerbation of delayed hypoperfusion during early reperfusion (6 hours); however, blood flow defects at later recovery time points remain to be excluded. These results may have implications for HS therapy in clinical ischemic stroke.

Animals↗
PubMed1999

Regional expression of heat shock protein 72 mRNA following mild and severe hypoxia in neonatal piglet brain.

The present study examined the effect of hypoxia on expression of 72-kDa heat shock protein (hsp72) mRNA in the newborn brain. The studies were carried out in anesthetized and mechanically ventilated newborn piglets, age 3-5 days. Hypoxic insult was induced by decreasing the fraction of inspired oxygen (FiO2) from 21% to 6% or 10% for 1 h. Oxygen pressure in the microvasculature of the cortex (cortical pO2) was measured by oxygen dependent quenching of the phosphorescence of phosphor dissolved in blood. Following the two hours of normoxic recovery, regional expression of the 72-kDa heat shock protein (hsp72) mRNA was determined using in situ hybridization and autoradiography. Two grades of hypoxia were studied. Mild hypoxia (cortical pO2 = 10-30 mm Hg) induced the expression of hsp72 mRNA predominantly in the subcortical white matter. In individual animals of this group, the extent of expression varied from isolated regions to widespread involvement of the white matter. Severe hypoxia (cortical pO2 = 3-10 mm Hg) induced the expression of hsp72 mRNA in both white and gray matter regions, with strong expression occurring in the cerebral cortex of individual animals. The present results indicate that immature white matter is more sensitive than gray matter to the hypoxia induced expression of hsp72 mRNA. Further, increased expression of hsp72 mRNA may be an indicator of a pathologic degree of hypoxic stress, and the observed increase may indicate that in the newborn brain the immature white matter is particularly sensitive to injury by hypoxia-ischemia and reperfusion.

Animals↗
PubMed1999

Cationic lipids and polymers are able to enhance adenoviral infection of cultured mouse myotubes.

Adenovirus-mediated gene transfer has been used to promote efficient expression of various reporter and therapeutic transgenes such as minidystrophin in skeletal muscle tissue. However, down-regulation of the adenovirus internalisation receptors, alpha(v)/beta3 and alpha(v)beta5, in adult myofibres and in mature cultured myotubes makes them less susceptible to infection than neonatal muscle or cultured myoblasts. It has been reported elsewhere that adenoviral transduction of cells that are normally refractory to infection can be enhanced by complexing virus particles with cationic lipids or cationic polymers. In this study we describe increased levels of adenovirus-mediated transduction of cultured C2C12 myotubes, when the vector is complexed with either of the cationic lipids Lipofectamine or 1,3-dioleoyloxy-2-(6-carboxyspermyl)propylamide (DOSPER) or the cationic polymer polyethylenimine. The presence of polycations allowed a smaller dose of adenovirus vector to be used to attain the same level of infection seen with adenovirus alone, which has important relevance to future in vivo studies. Electron microscopic analysis of adenovirus/polycation complexes showed large aggregates as opposed to single adenovirus particles in the absence of polycations. Finally, by complexing adenovirus particles with polycations, partial protection against the neutralising effect of adenovirus antiserum was observed.

Adenoviridae↗
PubMed1998

Prehospital treatment of acute asthma in a rural state.

BACKGROUND: Acute asthma exacerbations can be life threatening and are recognizable to emergency medical service (EMS) personnel; however, the therapies and medications which these emergency service personnel can use to treat exacerbations are limited. Several studies have demonstrated the effective use of beta2-agonist therapy in the treatment of patients complaining of wheezing or dyspnea, yet few EMS personnel can administer them. OBJECTIVE: The purpose of this study was to determine what therapeutic interventions emergency personnel around the state of New Mexico could use when responding to a call for a severe asthma exacerbation. METHODS: Questionnaires were distributed over a period of three years, 1992-1994, to all Emergency Service Agencies in New Mexico. RESULTS: Eighty percent of the emergency medical personnel administer oxygen to patients experiencing acute asthma exacerbations. Seventeen percent of EMS personnel administer epinephrine, 4% administer steroids, and only 23% administer beta2 agonists. Only in more populated areas were EMS personnel allowed to administer beta2 agonists, and those personnel had to have at least intermediate-level training. Most emergency response teams in the state consisted of EMT Basics and provided only basic life support services. In rural New Mexico, transport to a hospital can often take over one hour, which left EMS crews feeling helpless. CONCLUSIONS: We conclude that due to the rural nature of New Mexico, EMS personnel should be trained in the use of beta2 agonists and allowed to administer them to patients with acute asthma exacerbations. In addition, standard protocols for the pre-hospital management of acute asthma exacerbations should be instituted.

Acute Disease↗
PubMed1997

BOX-polymerase chain reaction-based DNA analysis of nonserotypeable Streptococcus pneumoniae implicated in outbreaks of conjunctivitis.

Nonserotypeable isolates predominate in epidemic conjunctivitis caused by Streptococcus pneumoniae. Previous evaluations of outbreaks of pneumococcal conjunctivitis have relied on epidemiologic factors and the nontypeability of the isolates to infer that a single clone was involved. In the present study, BOX-polymerase chain reaction DNA analysis was used to characterize nonserotypeable S. pneumoniae isolated by conjunctival culture during a recent conjunctivitis outbreak and to compare these isolates with those from outbreaks described earlier. The recent outbreak was caused by a single pneumococcal clone. Outbreaks in separate parts of the United States in 1980-1981 were all caused by the same clone. Cluster analysis revealed a high degree of genetic relatedness among isolates causing conjunctivitis compared with that among other nonserotypeable S. pneumoniae, with the closest relatedness being found among the 1996 and 1980-1981 conjunctival isolates.

Conjunctivitis↗