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E R Chilvers

Publications and source records attributed to E R Chilvers.

At least 73 records · Page 4Linked to original sources
PubMed1992

Quantification of right to left shunt at rest and during exercise in patients with pulmonary arteriovenous malformations.

BACKGROUND: Current treatment of patients with pulmonary arteriovenous malformations requires serial embolisations by means of steel coils or balloons. Measurement of right to left shunt is the most specific index of response to treatment. A new method of measuring shunt has been developed that is less invasive than traditional methods. METHODS: Right to left pulmonary shunt (expressed as percentage of cardiac output) was measured at rest in 19 patients with pulmonary arteriovenous malformations and six normal subjects by using intravenously injected albumin microspheres labelled with technetium-99m. The technique was compared with a simultaneous shunt measurement in subjects breathing 100% oxygen while they rested. The microsphere technique was adapted to measure the right to left shunt during exercise in 12 patients and five normal subjects with a new method of quantification. RESULTS: The mean (SD) shunt at rest as measured by the microsphere method was 23.2% (15.6%) in the patients and 2.7% (1.2%) in the normal subjects. When these values were compared with those of the 100% oxygen method the difference in mean values was 1% and the limits of agreement between the two methods -32% to +45%. The microsphere method is less invasive (arterial blood gas sampling is not required), quicker, and more comfortable for patients than the 100% oxygen method. In five of the normal subjects the mean (SD) 99mTc microsphere shunt increased from 2.9% (1.3%) at rest to 5.1% (2.9%) during exercise. In the 12 patients studied during exercise the shunt increased from 33.7% (12.7%) at rest to 41.7% (13.3%) during exercise in eight but decreased from 22.6% (2.4%) at rest to 17.6% (2.2%) during exercise in four. Arterial desaturation during exercise correlated with change in the size of the right to left shunt during exercise (r = +0.80). CONCLUSIONS: The microsphere method allows measurement of right to left shunt at rest and during exercise. Serial measurements at rest provide a simple, safe assessment of the physiological response to embolisation in patients with pulmonary arteriovenous malformations.

Adolescent↗
PubMed1991

Beta-adrenoceptor induced inhibition of muscarinic receptor-stimulated phosphoinositide metabolism is agonist specific in bovine tracheal smooth muscle.

The ability of the beta-adrenoceptor agonist isoprenaline to inhibit agonist-stimulated phosphoinositide metabolism was examined in bovine tracheal smooth muscle slices prelabelled with [3H]inositol. Accumulation of [3H]inositol phosphates was enhanced by the muscarinic agonists carbachol, oxotremorine and pilocarpine although the latter were only partial agonists for this response. Histamine stimulation of [3H]inositol phosphates was sensitive to mepyramine but maximal responses were only comparable to those of pilocarpine. Preincubation of tracheal slices with isoprenaline reduced the maximal phosphoinositide response to histamine and pilocarpine but the responses to carbachol and oxotremorine were unaffected. The inhibitory effect of isoprenaline (IC50 = 0.04 microM) was reversed competitively by 1 microM propranolol. The non-selective phosphodiesterase inhibitor isobutylmethylxanthine (IBMX) (1 mM) resulted in a more severe suppression of the histamine and pilocarpine responses and also produced a significant suppression of the maximal response to oxotremorine and a small shift in the carbachol dose-response curve. The different susceptibility of agonist-stimulated phosphoinositide hydrolysis to isoprenaline and IBMX are discussed in relation to the relative intrinsic activity of the agonists and/or the role of different muscarinic receptor subtypes.

1-Methyl-3-isobutylxanthine↗
PubMed1991

Determination of mass changes in phosphatidylinositol 4,5-bisphosphate and evidence for agonist-stimulated metabolism of inositol 1,4,5-trisphosphate in airway smooth muscle.

Stimulation of muscarinic receptors in bovine tracheal smooth muscle (BTSM) causes a sustained increase in muscle tone, but a transient increase in the second messenger Ins(1,4,5)P3. To examine whether this brief increase in Ins(1,4,5)P3 mass results from transient formation or is due to agonist-stimulation of Ins(1,4,5)P3 metabolism, we have studied the relationship between mass changes in PtdIns(4,5)P2 and Ins(1,4,5)P3 accumulation, and changes in [3H]InsP3, [3H]PtdIns, [3H]PtdInsP1 and [3H]PtdInsP2 in carbachol-stimulated myo-[3H]inositol-prelabelled BTSM slices. Carbachol (0.1 mM) caused a rapid transient increase in Ins(1,4,5)P3 concentration (basal, 12.9 +/- 0.8 pmol/mg of protein; 5 s carbachol treatment, 27.1 +/- 1.5 pmol/mg of protein), with values returning to basal levels by 30 s, but a sustained accumulation of total [3H]InsP3s, with [3H]Ins(1,3,4)P3 being the predominant isomer present at later time points. In contrast, PtdIns(4,5)P2 mass, determined by radioreceptor assay of Ins(1,4,5)P3 in desalted alkaline hydrolysates of acidified chloroform/methanol tissue extracts, declined rapidly (basal, 941 +/- 22 pmol/mg of protein; 120 s carbachol, 365 +/- 22 pmol/mg of protein; t1/2 14 s) and remained at this new steady-state level for at least 20 min in the continued presence of carbachol. Addition of 10 microM-atropine 2 min after carbachol caused a prompt return of PtdIns(4,5)P2 concentration to prestimulated values (t1/2 210 s). Ongoing resynthesis of PtdIns(4,5)P2 after carbachol stimulation was demonstrated in [3H]inositol-labelled tissue by observing a persistent increase in the specific radioactivity of [3H]PtdInsP2, shown to be exclusively [3H]PtdIns(4,5)P2, over a 10 min period. These findings strongly suggest the occurrence of persistent receptor-mediated increases in PtdIns(4,5)P2 hydrolysis and Ins(1,4,5)P3 formation which, in conjunction with the transient accumulation of Ins(1,4,5)P3 observed, provide evidence that regulation of the metabolism of Ins(1,4,5)P3 is a major determinant of Ins(1,4,5)P3 concentration in this tissue under agonist-stimulated conditions.

Animals↗
PubMed1991

Platelet-activating factor stimulates a rapid accumulation of inositol (1,4,5)trisphosphate in guinea pig eosinophils: relationship to calcium mobilization and degranulation.

The effect of platelet-activating factor (PAF) on inositol (1,4,5)trisphosphate (Ins[1,4,5]P3) mass, calcium mobilization, and the release of granule enzymes was studied on guinea pig peritoneal eosinophils (EOSs). PAF evoked a concentration-dependent accumulation of Ins(1,4,5)P3 with a drug concentration that elicits 50% of the maximum attainable response (EC50) of 10 nmol/L; the production of this second messenger was maximal at 1 mumol/L of PAF. Kinetic analysis of PAF (1 mumol/L)-induced Ins(1,4,5)P3 accumulation demonstrated it to be transient with a 3.8-fold increase over resting levels observed at 5 seconds. Thereafter, the level of Ins(1,4,5)P3 declined, returning to vehicle-treated levels 60 seconds after PAF challenge. Lyso-PAF, the inactive precursor and metabolite of PAF, was inactive at all concentrations examined. PAF also induced a rapid, concentration-dependent (EC50, 12 nmol/L) rise in the cytosolic-free calcium concentration ([Ca++]i) in fura 2-AM-loaded EOSs that was transient, peaking after the maximum increase in Ins(1,4,5)P3 mass was observed. A highly significant positive correlation was found between the peak increase in Ins(1,4,5)P3 and the peak rise in [Ca++]i. Functionally, PAF evoked a concentration-dependent release of granule constituents from both the small (arylsulfatase B; EC50, 3 nmol/L) and specific (EOS peroxidase; EC50, 2.7 nmol/L) granules that lagged, temporally, behind both Ins(1,4,5)P3 accumulation and the rise in [Ca++]i. Both the biochemical and functional effects of PAF examined in this study were antagonized by WEB 2086 (300 nmol/L), a selective PAF receptor-blocking drug. It is concluded that stimulus (PAF)-response coupling in guinea pig peritoneal EOSs may involve the receptor-mediated formation of Ins(1,4,5)P3 and subsequent release of intracellularly stored Ca++. This sequence of events may link PAF receptor activation to Ca(++)-dependent cellular responses, such as degranulation.

Animals↗
PubMed1991

Lack of effect of zaprinast on methacholine-induced contraction and inositol 1,4,5-trisphosphate accumulation in bovine tracheal smooth muscle.

1. The effects of zaprinast (M&B 22948), a selective guanosine 3':5'-cyclic monophosphate (cyclic GMP) phosphodiesterase inhibitor, and sodium nitroprusside on cyclic GMP content, phosphoinositide hydrolysis and airway smooth muscle tone were examined in flurbiprofen pretreated bovine tracheal smooth muscle (BTSM). 2. Anion-exchange chromatography of the soluble fraction of BTSM homogenates resolved three peaks of Ca2+/calmodulin-independent phosphodiesterase (PDE) activity that corresponded to type Ia (cyclic GMP-specific, zaprinast-inhibitable), type II (cyclic GMP-stimulated) and type IV (Ro 20 1724-inhibitable) PDE isoenzymes. Zaprinast caused a selective inhibition of the type Ia PDE isoenzyme (IC50 0.94 microM) with respect to the type II and IV (IC50 s 93 microM and 197 microM respectively) isoenzymes. 3. Pretreatment of BTSM strips with zaprinast (10 microM) for 20 min affected neither the initial rate of force development, nor the resultant magnitude of contraction induced by methacholine (10 microM). In addition, zaprinast (10 microM; 20 min) did not affect the cumulative concentration-response relationship induced by methacholine. In contrast, sodium nitroprusside (300 microM) either alone, or in combination with zaprinast (10 microM), significantly attenuated tone induced by low, but not high concentrations of methacholine. This resulted in a non-parallel, rightwards shift of the methacholine concentration-response curves (nitroprusside: 4.0 fold; nitroprusside/zaprinast: 4.8 fold at the EC50 values), without a reduction in the maximum tone generated. 4. In BTSM slices, zaprinast (10 or 100 microM) did not influence basal or methacholine (10 microM)-stimulated cyclic GMP accumulation or inositol 1,4,5-trisphosphate (Ins(1,4,5)P3) mass accumulation over a 60s incubation period, although it did significantly increase cyclic GMP content over longer (30 min) stimulation periods. 5. In [3H]-inositol prelabelled BTSM slices, stimulated in the presence of 5mM LiCl, methacholine (10 microM) caused a marked increase in total [3H]-inositol phosphate accumulation. This effect was not inhibited by zaprinast (10 microM), sodium nitroprusside (300 microM), or a combination of these drugs despite these agents markedly increasing tissue cyclic GMP content. 6. These findings demonstrate that despite zaprinast being a potent and selective inhibitor of the type Ia PDE isoenzyme in a cell-free system, this drug only increases cyclic GMP content in BTSM following prolonged agonist-stimulation. This may explain its lack of inhibitory effect on methacholine-induced tone. The inability of drugs which increase tissue cyclic GMP content and exhibit anti-spasmogenic activity to inhibit methacholine-stimulated Ins(1,4,5)P3 formation suggests that, unlike vascular smooth muscle, cyclic GMP-dependent mechanisms do not regulate receptor-mediated phosphoinositide hydrolysis in BTSM.

3',5'-Cyclic-GMP Phosphodiesterases↗
PubMed1990

Heterogeneity of [3H]inositol 1,4,5-trisphosphate binding sites in adrenal-cortical membranes. Characterization and validation of a radioreceptor assay.

1. The characterization of a radioreceptor assay for determining Ins(1,4,5)P3 concentration in tissue extracts is described which utilizes the binding of [3H]Ins(1,4,5)P3 to an adrenal-cortex membrane fraction. 2. Analysis of [3H]Ins(1,4,5)P3 binding by isotope dilution demonstrated an apparent single population of binding sites (KD 3.65 +/- 0.18 nM, Bmax. 872 +/- 70 fmol/mg of protein). Specific binding of [3H]Ins(1,4,5)P3 was enhanced at alkaline pH values (maximum at pH 8.5), with complete loss of specific binding at pH less than 6. These binding sites displayed strict stereo- and positional specificity for Ins(1,4,5)P3, with L-Ins(1,4,5)P3, Ins(1,3,4)P3 and DL-Ins(1,3,4,5)P4 causing 50% displacement of specific [3H]Ins(1,4,5)P3 binding (IC50 values) at concentrations of 14 +/- 3 microM, 3.0 +/- 0.3 microM and 0.53 +/- 0.03 microM respectively. 3. Kinetic analysis of binding data, however, revealed a high-affinity [3H]Ins(1,4,5)P3 binding site (KD 0.052 nM) in addition to the lower-affinity site (KD 2.53 nM) already demonstrated in displacement studies. 4. It is shown that the presence of the high-affinity site can be exploited to increase the sensitivity of the [3H]Ins(1,4,5)P3 radioreceptor assay, allowing accurate detection of 20 fmol of Ins(1,4,5)P3 in 300 microliters of tissue extract. 5. Further validation of the specificity of the above assay for Ins(1,4,5)P3 was provided by incubating tissue extracts with either a 5-phosphatase or 3-kinase preparation. It was shown that identical loss occurred of both Ins(1,4,5)P3 mass and [3H]Ins(1,4,5)P3, added to parallel incubations. 6. The ability of the assay to measure basal and agonist-stimulated increases in Ins(1,4,5)P3 concentration has been demonstrated with rat cerebral cortex and bovine tracheal smooth-muscle slices and a range of cultured and isolated cell preparations.

Adrenal Cortex↗
PubMed1990

Characterisation of stereospecific binding sites for inositol 1,4,5-trisphosphate in airway smooth muscle.

1. A 'P2' membrane fraction of bovine tracheal smooth muscle displays high affinity (KD 3.8 +/- 0.2 nM), saturable (Bmax 1003 +/- 170 fmol mg-1 protein) and reversible binding of D-myo[3H]-inositol 1,4,5-trisphosphate ([3H]-Ins(1,4,5)P3). 2. This binding site shows strict stereo- and positional specificity for the D-Ins(1,4,5)P3 isomer with L-Ins(1,4,5)P3, DL-Ins(1,3,4,5)P4 and D-Ins(1,3,4)P3 displacing [3H]-Ins(1,4,5)P3 with Ki values of 20 microM, 0.35 microM and 2.4 microM, respectively. 3. Specific binding of [3H]-Ins(1,4,5)P3 is enhanced at alkaline pH values (maximal at pH 7.75) and, in distinct contrast to [3H]-Ins(1,4,5)P3 binding in rat cerebellum membranes, is not inhibited by Ca2+ (5-500 microM). 4. Heparin displaces [3H]-Ins(1,4,5)P3 specific binding with an IC50 of 7.6 +/- 1.0 micrograms ml-1. 5. Comparative studies demonstrated specific [3H]-Ins(1,4,5)P3 binding in bovine cardiac atrial preparations (Bmax 75 +/- 5 fmol mg-1 protein) and very low specific [3H]-Ins(1,4,5)P3 binding in bovine cardiac ventricle and skeletal muscle membranes (less than or equal to 25 fmol mg-1 protein).

Animals↗
PubMed1990

Phosphoinositide metabolism in airway smooth muscle.

Contraction of airway smooth muscle (ASM) results from an increase in cytoplasmic free Ca2+ and appears to be independent of changes in membrane potential or the presence of extracellular Ca2+. Inositol 1,4,5-trisphosphate (Ins(1,4,5)P3), the product of receptor-mediated hydrolysis of a membrane phosphoinositide, phosphatidylinositol 4,5-bisphosphate, is capable of releasing Ca2+ from intracellular stores in this tissue and has been proposed as the intracellular second messenger responsible for agonist-induced changes in cytosolic Ca2+ and hence contraction. In this report, we discuss the evidence for this signaling system in ASM and present new data on mass changes in Ins(1,4,5)P3 in carbachol-stimulated bovine tracheal smooth muscle. The rapid, transient accumulation of this second messenger in ASM is thought to reflect regulation of the enzymes involved in the metabolism rather than the synthesis of this inositol polyphosphate. The potential mechanisms of this regulation are discussed in relation to the initiation and maintenance of contraction in ASM.

Animals↗
PubMed1990

Effect of percutaneous transcatheter embolization on pulmonary function, right-to-left shunt, and arterial oxygenation in patients with pulmonary arteriovenous malformations.

The effects of percutaneous transcatheter embolization on pulmonary function and exercise capacity were assessed in 15 patients with pulmonary arteriovenous malformations (PAVM). Vital capacity (VC), FEV1, DLCO, SaO2, exercise performance, and right-to-left shunt (100% oxygen method) were measured before and 2 to 6 months after treatment. Surgical correction had been attempted in 9 patients prior to referral, and 11 had associated hereditary hemorrhagic telangiectasia (HHT). Lung function tests before intervention showed normal VC and FEV1/VC ratios, reduced DLCO (mean 71% predicted, range 36 to 123%), a resting supine SaO2 of 86% (range 67 to 95%) and mean shunt fraction of 33% (range 15 to 47%). Despite further marked falls in SaO2 on exertion, exercise capacity was well preserved. Following steel coil embolization of all PAVM with a feed vessel internal diameter greater than 3 mm (one to four sessions per patient), mean shunt fraction improved from 33 to 19% and resting SaO2 from 86 to 92% with no change in VC. A consistent improvement in diffusing capacity was seen only in patients with coexisting HHT. Exercise capacity increased in the majority (unchanged in 6), and SaO2 during maximal exercise improved in all except one patient. There were no long-term complications following embolization. These findings indicate that embolization of all macroscopic PAVM, undertaken primarily to reduce the risk of paradoxical embolization, is safe and results in substantial improvements in resting and exercise SaO2 without evidence of loss of normal lung. The right-to-left shunts remaining following embolization may reflect the presence of numerous microscopic PAVM in these patients.

Adolescent↗
PubMed1990

Formation of inositol polyphosphates in airway smooth muscle after muscarinic receptor stimulation.

The effect of muscarinic-receptor stimulation on [3H]inositol mono-, bis-, tris- and tetrakisphosphate (InsP1, InsP2, InsP3 and InsP4) accumulation was examined in bovine tracheal smooth muscle slices prelabeled with myo-[3H]inositol. Carbachol (0.1 mM) caused a rapid increase in [3H]InsP3 and [3H]InsP2 followed by delayed increases in [3H]InsP1 and [3H]InsP4 accumulation. Analysis of the [3H]InsP3 isomers by HPLC showed an immediate although transient increase in [3H]Ins(1,4,5)P3 with a progressive and sustained accumulation of [3H]Ins(1,3,4)P3. [3H]Ins(1,3,4)P3 was confirmed as the predominant (greater than 80%) [3H]InsP3 isomer present at 1 and 30 min using an enzymatic method which causes selective hydrolysis of Ins(1,3,4)P3. Lithium enhanced markedly the carbachol-stimulated accumulation of [3H]InsP1 and [3H]InsP2 with a lower potency than that observed in other tissues but had no significant influence on [3H]InsP3 or [3H]InsP4 values. These data support a role for Ins(1,4,5)P3 in initiating airway smooth muscle contraction and indicate the importance of the Ins(1,3,4,5)P4/Ins(1,3,4)P4 pathway in this tissue.

Animals↗
PubMed1989

Characterization of agonist-stimulated incorporation of myo-[3H]inositol into inositol phospholipids and [3H]inositol phosphate formation in tracheal smooth muscle.

The effects of the muscarinic agonist carbachol, histamine and bradykinin on incorporation of [3H]inositol into the phosphoinositides and the formation of [3H]InsPs were examined in bovine tracheal smooth-muscle (BTSM) slices labelled with [3H]inositol. These agonists result in substantial and dose-related increases in the incorporation of [3H]inositol into the phospholipids. Carbachol and histamine stimulated the incorporation of [3H]inositol into the phospholipids to the same degree, despite histamine being only 35% as effective as carbachol on [3H]InsP accumulation. Histamine and carbachol, at maximal concentrations, were non-additive with respect to both the stimulated incorporation of [3H]inositol and [3H]InsP formation. For carbachol this effect on incorporation was found to occur to a similar extent in PtdInsP and PtdInsP2 as well as PtdIns. The initial effect of carbachol on [3H]inositol incorporation was rapid (maximal by 10 min); however, with prolonged stimulation large secondary declines in PtdInsP and PtdInsP2 labelling were observed, with depletion of the much larger PtdIns pool only evident in the presence of Li+. Lowering buffer [Ca2+] increased the incorporation of [3H]inositol under basal conditions, but did not attenuate the subsequent agonist-stimulated incorporation effect. The large changes in specific radioactivity of the phosphoinositides, and consequently the [3H]InsP products, after carbachol stimulation resulted in the apparent failure of atropine to reverse the [3H]InsP response completely. Labelling muscle slices with [3H]inositol in the presence of carbachol or labelling for longer periods (greater than 6 h) prevented subsequent carbachol-stimulated effects on incorporation without significantly altering the dose-response relationship for carbachol-stimulated [3H]InsP formation and resulted in steady-state labelling conditions confirmed by the ability of atropine to reverse fully the [3H]InsP response to carbachol. This study demonstrates the profound effects of a number of agonists on [3H]inositol incorporation into the phospho- and polyphosphoinositides in BTSM with important consequent changes in the specific radioactivity of these lipids and the resulting [3H]InsP products. In addition, a selective depletion of PtdInsP and PtdInsP2 over PtdIns has been demonstrated with prolonged muscarinic-receptor stimulation.

Animals↗
PubMed1989

Mass changes of inositol(1,4,5)trisphosphate in trachealis muscle following agonist stimulation.

Agonist-stimulated changes in D-Ins(1,4,5)P3 has been examined in tracheal smooth muscle using a specific radioreceptor assay utilizing the binding of [3H] or [32P]Ins(1,4,5)P3 to a bovine adrenal cortex preparation. Carbachol produced a maximal increase in Ins(1,4,5)P3 concentration after 5 s (basal: 12.9 +/- 0.8; stimulated: 27 +/- 1.5 pmol/mg protein) with an EC50 of 6.7 +/- 0.8 microM. With longer stimulation periods Ins(1,4,5)P3 rapidly returned to basal values by 30 s. This is the first report of mass measurements of Ins(1,4,5)P3 in smooth muscle.

Animals↗
PubMed1989

A simple enzymic method to separate [3H]inositol 1,4,5- and 1,3,4-trisphosphate isomers in tissue extracts.

A novel method to separate [3H]Ins(1,4,5)P3 and [3H]Ins(1,3,4)P3 in tissue extracts is described. It is based on the selective metabolism of Ins(1,3,4)P3 by a crude cerebral supernatant in a Mg2+-free buffer followed by separation of [3H]inositol trisphosphates using conventional anion-exchange chromatography. Evaluation of the assay was performed using [3H]Ins(1,3,4)P3 standards and tissue extracts containing different proportions of [3H]Ins(1,4,5)P3 and [3H]Ins(1,3,4)P3. Parallel h.p.l.c. separations of extracts established the selective and complete metabolism of [3H]Ins(1,3,4)P3 under the above conditions and demonstrated that the enzymic method provides an accurate estimate of the trisphosphate isomers in rat cerebral cortex, parotid gland and bovine tracheal smooth muscle.

Animals↗
PubMed1989

Changes in extracellular calcium within the physiological range influence receptor-mediated inositol phosphate responses in brain and tracheal smooth muscle slices.

The effect of changes in extracellular calcium concentration ([Ca2+]e) on the incorporation of myo-[2-3H]-inositol into phosphoinositides and agonist-stimulated 3H-inositol phosphates (3H-InsPs) was examined in rat cerebral cortex and bovine tracheal smooth muscle slices. In brain slices, reduction in [Ca2+]e from 2.4 to 1.2 mmol/l resulted in an approximate doubling of the carbachol and noradrenaline-stimulated 3H-InsP response with no effect on the EC50 values. An identical effect of varying [Ca2+]e was observed for carbachol-stimulated 3H-InsP formation in tracheal smooth muscle with a further increase in 3H-InsPs evident at [Ca2+]e 0.6 mmol/l. In this tissue the effect of changes in [Ca2+]e on the incorporation of myo-[2-3H]-inositol into the total phosphoinositide pool directly paralleled the changes in 3H-InsPs except in conditions of no added calcium when 3H-InsP responses were markedly impaired. Additional studies in brain slices using buffer where the added calcium varied between 0 and 2.4 mmol/l, showed that both the carbachol stimulated formation of separate inositol phosphates during short incubation periods and incorporation of myo-[2-3H]-inositol into PtdInsP and PtdInsP2 under basal conditions was maximal at [Ca2+]e 0.3 mmol/l. Omitting Ca2+ from the buffer resulted in maximal labelling of PtdIns but a decrease in PtdInsP and PtdInsP2 labelling (compared with the level at [Ca2+]e 0.3 mmol/l) and a markedly impaired inositol polyphosphate response. Alterations in [Ca2+]e following 3H-inositol labelling but immediately prior to carbachol stimulation did not influence 3H-inositol polyphosphate responses. It is therefore clear that even relatively small changes in [Ca2+]e markedly influence agonist-stimulated 3H-InsP responses in brain and tracheal smooth muscle slices and that these reflect changes in the labelling of substrate inositol lipids.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Bronchoalveolar lavage in an immunosuppressed rabbit model of invasive pulmonary aspergillosis.

A rabbit model of invasive aspergillosis has been used to investigate the pathogenesis of Aspergillus infection in the immunosuppressed host. The animals received hydrocortisone daily and a single dose of cyclophosphamide 2 days prior to intratracheal instillation of conidia from Aspergillus fumigatus. Bronchoalveolar lavage (BAL) was performed in 3 infected and 2 control saline treated animals sacrificed on days 1, 2, 4, 7 and 10 following inoculation. Infective load within the lung was quantified using an assay for chitin which is an important component of fungal cell walls (in particular the hyphal cell wall) and is not present in vertebrate tissue. The total BAL white cell count did not discriminate between infected and saline treated animals and Aspergillus was cultured from one lavage specimen only. Infected animals developed a marked neutrophil alveolitis by day 2 in contrast to a near total absence of neutrophils in the lavages of the control animals. Phagocytosis of conidia by alveolar macrophages was prominent but did not prevent progressive infection as confirmed by measurement of lung chitin. This pattern of cellular response within the alveolar airspace reflects the complex nature of the response to Aspergillus infection in the immunosuppressed host.

Analysis of Variance↗