CrkRS

We have isolated and characterised a novel human protein kinase, Cdc2-related kinase with an arginine/serine-rich (RS) domain (CrkRS), that is most closely related to the cyclin-dependent kinase (CDK) family. CrkRS is a 1490 amino acid protein, the largest CDK-related kinase so far isolated. The protein kinase domain of CrkRS is 89% identical to the 46 kDa CHED protein kinase, but outside the kinase domains the two proteins are completely unrelated. CrkRS has extensive proline-rich regions that match the consensus for SH3 and WW domain binding sites, and an RS domain that is predominantly found in splicing factors. CrkRS is ubiquitously expressed in tissues, and maps to a single genetic locus. There are closely related protein kinases in both the Drosophila and Caenorhabditis elegans genomes. Consistent with the presence of an RS domain, anti-CrkRS antibodies stain nuclei in a speckled pattern, overlapping with spliceosome components and the hyperphosphorylated form of RNA polymerase II. Like RNA polymerase II, CrkRS is a constitutive MPM-2 antigen throughout the cell cycle. Anti-CrkRS immunoprecipitates phosphorylate the C-terminal domain of RNA polymerase II in vitro. Thus CrkRS may be a novel, conserved link between the transcription and splicing machinery.

Children followed with difficulty: how do they differ?

OBJECTIVE

To determine if very low birthweight children followed with ease differ in any perinatal or sociodemographic characteristics, or outcomes, compared with children followed with more difficulty.

METHODOLOGY

Consecutive children of birthweight < 1000 g or with gestational ages < 28 weeks born in 1991 (n = 51) or of birthweight < 1500 g born in 1992 (n = 166) at the Royal Women's Hospital, Melbourne, surviving to 5 years of age, were assessed at 5 years of age, corrected for prematurity. Those who attended on the first mutually agreed appointment without substantial reluctance were considered to have been followed with ease. The remainder were considered to have been followed with difficulty. Outcomes included impairments such as cerebral palsy, blindness, deafness, and low IQ. Children had a disability if they had any of cerebral palsy, blindness, deafness requiring amplification, or an IQ more than 1 SD below the mean.

RESULTS

Of the 217 survivors, 204 (94%) were assessed fully at 5 years of age. Of the 204 children assessed, 153 (75%) were followed with ease, and 51 (25%) with difficulty. Of data available in the perinatal period, significantly fewer children followed with more difficulty came from intact families, and more of their mothers had fewer than 12 years of schooling. More children followed with difficulty had a disability (41% compared with 19%), as they predominantly had lower IQ scores (mean difference in IQ - 12.7, 95% confidence interval - 18.0, - 7.4). The association between difficulty of assessment and both higher rates of disability and lower IQ scores remained after adjustment for significant perinatal and sociodemographic variables.

CONCLUSIONS

Children followed with difficulty can partly be recognized on several sociodemographic characteristics in the perinatal period, and have substantially worse sensorineural outcomes than those followed with ease. In any longitudinal study, the more incomplete the follow up, the lower will be the rate of adverse sensorineural outcome.

Dynamic fibular function: a new concept

Fibular function has long been a point of controversy in the literature. Until recently the fibula's role during gait has been thought of as entirely static. A review of the literature reveals an important dynamic function for the fibula in maintaining ankle mortise stability during weight bearing. Roentgenographic and anatomical studies confirm the hypothesis of progressive distal fibular descent. A taut interosseous membrane and deepened mortise result when be flexors of the foot contract during stance phase. Congenital deformities of the ankle may stem from aberration in the dynamic role of the fibula. Stress fractures and problems resulting from impaired distal migration and synostosis formation are interpreted as disorders of the dynamic role of the fibula.

Arrestin isoforms dictate differential kinetics of A2B adenosine receptor trafficking

Adenosine mediates the activation of adenylyl cyclase via its interaction with specific A(2A) and A(2B) adenosine receptors. Previously, we demonstrated that arrestins are involved in rapid agonist-promoted desensitization of the A(2B) adenosine receptor (A(2B)AR) in HEK293 cells. In the present study, we investigate the role of arrestins in A(2B)AR trafficking. Initial studies demonstrated that HEK293 cells stably expressing arrestin antisense constructs, which reduce endogenous arrestin levels, effectively reduced A(2B)AR internalization. A(2B)AR recycling after agonist-induced endocytosis was also significantly impaired in cells with reduced arrestin levels. Interestingly, while overexpression of arrestin-2 or arrestin-3 rescued A(2B)AR internalization and recycling, arrestin-3 promoted a significantly faster rate of recycling as compared to arrestin-2. The specificity of arrestin interaction with A(2B)ARs was further investigated using arrestins fused to the green fluorescent protein (arr-2-GFP and arr-3-GFP). Both arrestins underwent rapid translocation (<1 min) from the cytosol to the plasma membrane following A(2B)AR activation. However, longer incubations with agonist (>10 min) revealed that arr-2-GFP but not arr-3-GFP colocalized with the A(2B)AR in rab-5 and transferrin receptor containing early endosomes. At later times, the A(2B)AR but not arr-2-GFP was observed in an apparent endocytic recycling compartment. Thus, while arrestin-2 and arrestin-3 mediate agonist-induced A(2B)AR internalization with relative equal potency, arrestin isoform binding dictates the differential kinetics of A(2B)AR recycling and resensitization.

A history of the dissolution of retained choledocholithiasis

BACKGROUND

Common duct calculi retained after gallbladder surgery continue to present a clinical challenge especially in the era of minimally invasive surgery. This review examines the strategy of dissolution therapy used throughout the history of biliary tract surgery and its use to the modern surgeon.

DATA SOURCES

Original journal articles and reviews were identified using standard surgical textbooks and MEDLINE. Keywords for searching included choledocholithiasis, dissolution, mono-octanoin, common duct stones, MTBE, cholic acid, and gallstones.

CONCLUSIONS

Dissolution therapy used initially as an alternative to open surgery is now used more effectively as an adjunct to laparoscopic or endoscopic biliary tract surgery. The current review demonstrates a majority of patients with retained choledocholithiasis respond to dissolution and can be safely managed without choledochotomy.

Influence of renal function on the pharmacokinetics of cerivastatin in normocholesterolemic adults

OBJECTIVE

The influence of impaired renal function on the pharmacokinetics of single and multiple doses of cerivastatin was evaluated in this nonrandomized, non-blinded, 7-day, multiple-dose study.

METHODS

Thirty-five adults between the ages of 21 years and 75 years with normal renal function (CL(CR) >90 ml/min/1.73 m2, n = 9), or patients with either mild (CL(CR) 61 ml/min/1.73 m2 to < or =90 ml/min/1.73 m2, n = 9), moderate (CL(CR) 30 ml/min/1.73 m2 to < or =60 ml/ min/1.73 m2, n = 8), or severe (CL(CR) <30 ml/min/ 1.73 m2, but not on dialysis, n = 9) renal impairment were given cerivastatin 0.3 mg daily each evening for 7 days. The steady-state pharmacokinetics of cerivastatin, including the area under the concentration-time curve (AUC)0-24, peak plasma concentration (Cmax), time to reach Cmax (tmax) and elimination half-life (t1/2), were determined on day 1 and day 7. The logarithm of the pharmacokinetic variables was analyzed using analysis of variance (ANOVA). Safety assessments included physical examination, fundoscopy, vital signs, electrocardiogram (ECG), adverse events, and laboratory safety indices.

RESULTS

The day-1 AUC in patients with mild renal impairment was similar to that of patients with normal function (19.6 microg/h/l vs 19.2 microg/h/l, respectively). However, the AUC for cerivastatin patients with moderate or severe renal impairment was 40-60% higher (30.8 microg/h/l and 29.0 microg/h/l, respectively). Cmax values for patients with normal, mild, moderate, and severe renal impairment were 3.3, 3.4, 4.6, and 5.2 microg/l, respectively. This modest increase in plasma cerivastatin levels is nearly equivalent to a 0.4-mg daily dose, which has been recently approved in the United States. The mean t1/2 of cerivastatin was less than 4.5 h in all patients, indicating that renal dysfunction did not promote cerivastatin accumulation. This observation was confirmed by the finding that the cerivastatin plasma levels on day 1 and day 7 were similar in all patient groups. Furthermore, the mean AUC and Cmax values for both demethylated and hydroxylated cerivastatin were similar in the patients with the most severe renal dysfunction to the corresponding values in healthy subjects. Cerivastatin was well tolerated in all patients irrespective of renal function. Adverse events were observed in 37% of the subjects; nearly all were mild and generally of short duration, and most resolved without intervention. Incidence of adverse events was similar across all three renal groups and the control group. There were no clinically significant laboratory changes other than those consistent with renal disease.

CONCLUSION

This study demonstrates that dosage adjustment of the daily 0.3-mg cerivastatin dose in patients with significant renal impairment is likely unnecessary.

Selective reduction in A2 adenosine receptor desensitization following antisense-induced suppression of G protein-coupled receptor kinase 2 expression

Phosphorylation of G protein-coupled receptors (GPCRs) by GPCR kinases (GRKs) is considered to play a critical role in the desensitization of responses mediated by these receptors. To explore the role of GRK2 in A2 adenosine receptor desensitization, we attempted to reduce specifically GRK2 expression in NG108-15 cells by stable transfection with an antisense rat GRK2 cDNA sequence. This yielded up to a 69% loss of GRK2 when compared with plasmid-transfected control cells, which correlated with a reduction in kinase activity when measured by the ability of cell lysates to promote light-dependent phosphorylation of rhodopsin. Levels of GRK3 were the same in antisense and plasmid-transfected controls. On addition of the A2 adenosine receptor agonist 5'-(N-ethylcarboxamido)adenosine, cyclic AMP accumulation was greater in GRK2 antisense cells as compared with plasmid control cells. In contrast, cyclic AMP accumulation via agonist stimulation of either IP-prostanoid or secretin receptors or by addition of forskolin was not significantly different among all clones examined. The increase in A2 adenosine receptor response could not be explained by changes in A2A adenosine receptor expression, as assessed by ligand binding experiments with the radioligand 2-3H-labelled 4-[2-[7-amino-2-(2-furyl)[1,2,4]triazolo[2,3-a][1,3,5]triazin-5-++ +ylamino]ethyl]phenol ([3H]ZM241385). These data show for the first time a direct correlation between expression of GRK2 and desensitization of natively expressed A2 adenosine receptors in intact cells, suggesting that GRK2 plays a major role in the regulation of these receptors. Key Words: G protein-coupled receptor kinase-G protein-coupled receptor-Antisense-NG108-15 cells-A2 adenosine receptors-Desensitization.

Pharmacological profile of ZD1611, a novel, orally active endothelin ETA receptor antagonist

The endothelins (ETs), potent vasoconstrictor peptides, have been implicated in the pathogenesis of various cardiovascular disorders. In the present study, we describe the novel, potent, orally active, selective ET(A) receptor antagonist ZD1611 [3-(4-[3-(3-methoxy-5-methylpyrazin-2-ylsulfamoyl)-2-pyridyl ]phenyl)- 2,2-dimethylpropanoic acid]. ZD1611 competitively inhibited (125)I-labeled ET-1 binding at human cloned ET(A) and ET(B) receptors with pIC(50) values of 8.6 +/- 0.1 and 5.6 +/- 0.1, respectively, showing 1000-fold selectivity for the ET(A) receptor. ZD1611 caused a parallel rightward shift of the concentration response curve to ET-1 in the rat isolated aorta yielding a concentration of antagonist that caused a 2-fold rightward shift in the ET-1-response curve (pA(2)) of 7.5 +/- 0.3. When administered i. v. to anesthetized rats and dogs, ZD1611 caused dose-related rightward shifts of partial dose-response curves to the precursor of ET-1, big ET-1. Threshold doses for significant antagonist activity were determined as 0.1 mg/kg and 0.3 mg/kg in the rat and dog, respectively. Importantly, ZD1611 was able to reverse an established big ET-1-induced pressor response in pithed rats in the presence of continuous big ET-1 infusion. Failure of ZD1611 to inhibit the BQ3020 (ET(B)-selective)-induced depressor response in pithed rats indicated a lack of activity at the endothelial ET(B) receptor. ZD1611 was orally active in the rat at 0.3 mg/kg and had a duration of action of more than 7 h, and, in the dog, a dose of 0.6 mg/kg p.o. was active for at least 6 h. In conclusion, these data demonstrate that ZD1611 is a potent and orally active, selective ET(A) receptor antagonist with a long duration of action which may be of therapeutic use.

Effect of G protein-coupled receptor kinase 2 on the sensitivity of M4 muscarinic acetylcholine receptors to agonist-induced internalization and desensitization in NG108-15 cells

NG108-15 cells express predominantly the M4 subtype of the muscarinic receptor for acetylcholine. Stimulation of these receptors by the agonist carbachol causes an inhibition of cellular adenylyl cyclase and a consequent fall in the intracellular cyclic AMP concentration. Pretreatment of the cells with carbachol caused both internalization and desensitization of the M4 receptor. Overexpression of G protein-coupled receptor kinase (GRK) 2 caused an increase in the rate constant for receptor endocytosis (from 0.06 to 0.18 min(-1)) and a decrease in the EC50 for carbachol stimulation of internalization (from 15 to 3 microM). Overexpression of a dominant negative form of GRK2 had more modest effects, reducing the rate constant for endocytosis (from 0.11 to 0.07 min(-1)) and increasing the EC50 for carbachol stimulation of internalization (from 8 to 17 microM). Neither GRK2 nor dominant negative GRK2 overexpression had any effect on the rate constant for receptor recycling following agonist removal. The time course and extent of receptor desensitization in control cells were identical to the corresponding values for receptor internalization, and the rate and extent of desensitization were again increased by GRK2 overexpression. Exposure of the cells to hyperosmolar sucrose (0.6 M) almost completely blocked agonist-induced receptor internalization in both control and GRK2-overexpressing cells. Sucrose treatment also blocked agonist-induced desensitization. We conclude that the internalization and desensitization of the M4 muscarinic receptor in NG108-15 cells can be modulated in response to changes in GRK2 activity and also that internalization plays a key role in desensitization.

The unstable distal radial fracture one year post Kapandji intrafocal pinning

Kapandji pinning has been proposed as the treatment of choice for unstable Colles' fractures. The aim of this paper is to evaluate our experience treating unstable Colles' type fractures using this technique. Over a nine month period, 36 patients with Colles' type fractures were treated operatively at St. Vincent's Hospital. 22 of these fractures were deemed unstable and were treated using percutaneous intrafocal Kapandji pinning. 20 of these patients were recalled for review at a mean of 11.3 month post injury. At this stage the wrist was examined clinically and radiologically. Initial satisfactory correction of deformity was achieved by this technique. Between the time of wire removal and final review, however, there was significant recurrence of dorsal angulation (P < 0.05), but no significant radial shortening on radiographs. The patients had a satisfactory clinical result in spite of these radiological parameters.

Anatomical and embryological considerations in the repair of a large vertex cephalocele. Case report

The case of a neonate with a large vertex cephalocele is presented. The anatomical features of this anomaly were evaluated by means of magnetic resonance imaging and magnetic resonance angiography. Fusion of the thalami, dysgenesis of the corpus callosum, and failure of adequate formation of the interhemispheric fissure were characteristics of the major cerebral anomalies associated with the cephalocele. The absence of a falx in the midline, a split configuration of the superior sagittal sinus, and a dysgenetic tentorium with a concomitant abnormal venous drainage pattern were found in association with a large dorsal cyst. Repair of the anomaly was undertaken on the 3rd postnatal day. A cerebrospinal fluid shunt was required to treat hydrocephalus on Day 30. The child is well at age 3 years, but with significant developmental delay. The pathogenesis of this vertex cephalocele relates to semilobar holoprosencephaly and dorsal cyst formation. In addition, a disturbance in the separation of the diencephalic portion of the neural tube from the surface ectoderm or skin during the final phases of neurulation had occurred to help create the large cephalocele. Detailed preoperative imaging studies and awareness of the embryology and anatomy of this lesion facilitated the repair of the cephalocele. The prognosis of the child is determined not only by the presence of hydrocephalus, but also by the number of associated major cerebral anomalies. Options for treatment are discussed.

Somatostatin receptor desensitization in NG108-15 cells. A consequence of receptor sequestration

In NG108-15 cells inhibition of both N-type calcium channel current and adenylyl cyclase by somatostatin (SRIF) was not sustained but rapidly desensitized in the continued presence of the drug. The degree and rate of desensitization were concentration-dependent, and the desensitization was homologous with respect to the delta-opioid receptor. We have been unable to obtain evidence for the involvement of G protein-coupled receptor kinases (GRKs) in this desensitization. SRIF-induced desensitization of N-type calcium channel currents was not reduced in cells stably overexpressing a dominant negative mutant of GRK2 or following intracellular dialysis with GRK2- and GRK3-blocking peptides or with heparin. Inhibitors of protein kinase A, protein kinase C, and protein kinase G were also without effect. In contrast, both the rate and degree of SRIF-induced desensitization were reduced by pretreatment with phenylarsine oxide or concanavalin A, both inhibitors of receptor endocytosis. Furthermore, SRIF-induced desensitization was enhanced by monensin, which prevents receptor recycling back to the plasma membrane. Similarly, SRIF-induced desensitization of adenylyl cyclase inhibition was not reduced in cells stably overexpressing dominant negative mutant GRK2 but was reduced in cells pretreated with the receptor endocytosis inhibitor hyperosmotic sucrose or concanavalin A. These data are consistent with the view that SRIF-induced desensitization in NG108-15 cells results from receptor internalization.

The effect of inhibitors of receptor internalization on the desensitization and resensitization of three Gs-coupled receptor responses

Many G protein-coupled receptors (GPCRs) are known to internalize following agonist exposure, however the relative importance of this mechanism for the desensitization and resensitization of different GPCRs is unclear. In the present study, we have pretreated NG108-15 cells with hypertonic sucrose or concanavalin A (con A), to investigate the effects of these inhibitors of internalization on the agonist-induced desensitization and subsequent resensitization of three Gs-coupled receptor responses. Incubation of cells with sucrose or con A did not affect subsequent acute agonist stimulation of the A2A adenosine receptor or the agonist-induced desensitization of this receptor response. However, the resensitization of the A2A adenosine receptor response following agonist removal was abolished in the presence of sucrose or con A. Sucrose or con A treatment affected neither the desensitization nor resensitization of IP-prostanoid receptor responsiveness. On the other hand con A but not sucrose reduced the agonist-induced desensitization of secretin receptor responsiveness. However, secretin receptor responsiveness did not resensitize within the time period studied whether or not inhibitors of internalization were present. These results indicate that receptor internalization appears to subserve different functions for different GPCRs.

Utility of clinical parameters of tissue oxygenation in a quantitative model of irreversible hemorrhagic shock

The aim of this study was to assess the value of parameters of tissue oxygenation in monitoring the progression to irreversibility in a quantitative model of hemorrhagic shock. Rats were bled to a mean arterial pressure of 40 mmHg and were maintained at this level by further blood withdrawal until the compensation endpoint; this point was defined as the time at which the rat was no longer able to maintain its blood pressure at this level and shed blood was required for transfusion. The shock period was maintained until 0%, 20%, 40%, or 50% of the maximum shed blood volume (MBV) had been returned (n = 10 in each group, total n = 40). The animals were then resuscitated with remaining shed blood plus twice MBV as lactated Ringer's solution to MAP > 80 mmHg. Blood gas and serum lactate samples were measured at baseline, compensation endpoint, and at the time of resuscitation, and 24 h survival was recorded. Increasing the severity of shock progressively worsened the acidosis, with increased base deficit and lacticacidemia, and deterioration in central venous oxygen saturation (CvO2). Tissue oxygenation parameters, particularly CvO2, predicted subsequent mortality. Lactate levels only predicted irreversibility in late, severe shock. This quantitative model of hemorrhagic shock showed that tissue oxygenation parameters can be used to monitor the progression from the decompensated phase of hemorrhagic shock to irreversibility. Furthermore, this experimental study suggests that venous indices may be a valuable tool in reflecting the severity of hemorrhagic insult in a setting when arterial blood samples may not be easily available.

Urban angina in the mountains: effects of carbon monoxide and mild hypoxemia on subjects with chronic stable angina

Seventeen men with stable angina pectoris who resided at or near sea level performed cardiopulmonary exercise stress tests after they were exposed to either carbon monoxide (3.9%), carboxyhemoglobin, or clean air. Investigators conducted the tests at sea level, and they simulated 2.1-km altitudes (i.e., reduced arterial oxygen saturation by approximately 4%) in a randomized double-blind experiment in which each subject acted as his or her own control. The duration of symptom-limited exercise, heart rate, indicators of cardiac ischemia and arrhythmia, blood pressure, and respiratory gas exchange were measured. Analyses of variance showed that both independent variables-altitude and carbon monoxide-significantly (p < or = .01) reduced total duration of exercise for the group as a whole (n=17) and reduced the time to onset of angina for a subset of 13 subjects who experienced angina during all four test conditions (p < .05). Time to onset of angina was reduced either after exposure to sea-level carbon monoxide (9%) or to simulated high-altitude clean-air exposures (11%), compared with clean air at sea level. Joint exposure to carbon monoxide at a simulated high altitude reduced the time to onset of angina, relative to clean air, by 18% (p < .05). Other cardiological, hemodynamic, and respiratory physiological parameters were also affected adversely by altitude and carbon monoxide exposures. None of the parameters measured were associated significantly with either altitude or carbon monoxide, indicating that the effects of carbon-monoxide-induced and high-altitude-induced hypoxia were additive. The results of this study suggest that high-altitude conditions exacerbate the effects of carbon monoxide exposures in unacclimatized individuals who have coronary artery disease.

Enhanced expression of G protein-coupled receptor kinase 2 selectively increases the sensitivity of A2A adenosine receptors to agonist-induced desensitization

1. G protein-coupled receptor kinases (GRKs) are thought to be important in mediating the agonist-induced phosphorylation and consequent desensitization of G protein-coupled receptor (GPCR) responses. We have previously shown that stable expression of a dominant negative mutant G protein-coupled receptor kinase 2 (GRK2) construct in NG108-15 mouse neuroblastoma x rat glioma cells suppresses the agonist-induced desensitization of A2A and A2B adenosine receptor-stimulated adenylyl cyclase activity (Mundell et al., 1997). To further determine the role of GRK2 in agonist-induced desensitization of these adenosine receptors, we stably overexpressed wild type GRK2 in NG108-15 cells. 2. In homogenates prepared from cells overexpressing GRK2, the acute stimulation of adenylyl cyclase by activation of A2A and A2B adenosine receptors was markedly reduced, but could be reversed by pretreating the cells with AD (adenosine deaminase), to remove extracellular adenosine from the medium. On the other hand, acute stimulation of adenylyl cyclase by secretin, iloprost, NaF and forskolin was the same in GRK2 overexpressing cells and plasmid-transfected control cells. 3. Cells overexpressing GRK2 were more sensitive to adenosine receptor agonist-induced desensitization than plasmid-transfected control cells. This effect was selective since the agonist sensitivity of desensitization for secretin and IP-prostanoid receptor-stimulated adenylyl cyclase activity was not affected by GRK2 overexpression. 4. These results further implicate GRK2 as the likely mechanism by which A2 adenosine receptors undergo short-term desensitization in NG108-15 cells, and indicate that even when overexpressed, GRK2 retains its substrate specificity for native receptors in intact cells. Furthermore, the susceptibility of GPCRs to desensitization appears to depend on the level of GRK expression, such that in cells that express high levels of GRK2, low agonist concentrations may be sufficient to trigger GRK-mediated desensitization.

Evidence for co-expression and desensitization of A2a and A2b adenosine receptors in NG108-15 cells

Using receptor-selective agonists and antagonists, the possible presence of both A2a and A2b adenosine receptor subtypes coupled to activation of adenylyl cyclase was investigated in NG108-15 neuroblastoma x glioma hybrid cells. The relatively non-selective adenosine receptor agonist 5'-(N-ethyl carboxamido)-adenosine (NECA; 1 nM-300 microM) produced a biphasic increase in adenylyl cyclase activity in cell homogenates, best fitted to two components with high (EC50 0.7 microM) and low (EC50 16.0 microM) potency, respectively. The selective adenosine A2a receptor agonist CGS-21680 (1 nM-300 microM) also produced a biphasic increase in adenylyl cyclase. The NECA-dependent increase in adenylyl cyclase activity was almost completely inhibited by the non-selective adenosine receptor antagonist xanthine amine congener (XAC; 30 microM), but only partially inhibited by the selective A2a adenosine antagonist 8-(3-chlorostyryl)caffeine (CSC; 1 microM). Experiments were also performed to investigate the time course of NECA-induced desensitization of putative A2a and A2b receptor responses. The A2a-response was quantified using 10 microM CGS-21680, whilst the A2b response was quantified using 100 microM NECA in the presence of 1 microM CSC. The t0.5 for desensitization for each subtype was found to be around 20 min. Neither activation (with dibutyryl cAMP; 1 mM) nor inhibition (with H-89; 10 microM) of cyclic AMP-dependent protein kinase altered the ability of NECA pretreatment to desensitize A2a or A2b receptor-activated adenylyl cyclase. However zinc (200 microM), an inhibitor of G-protein coupled receptor kinase 2 (GRK2), significantly reversed the agonist-induced desensitization of A2a and A2b receptor-activated adenylyl cyclase. These experiments suggest the co-existence of A2a and A2b receptors coupled in a stimulatory fashion to adenylyl cyclase in NG108-15 cells. Furthermore desensitization of A2a and A2b responses occurs at the same rate and may involve a G-protein-coupled receptor kinase.

G-CSF instillation into rat lungs mediates neutrophil recruitment, pulmonary edema, and hypoxia

Activated neutrophils (PMN) have been implicated in the pathogenesis of adult respiratory distress syndrome (ARDS). Granulocyte colony-stimulating factor (G-CSF) is essential for PMN production and activation of PMN functions. We have recently shown that levels of G-CSF mRNA in a rat model of hemorrhagic shock correlated with severity of shock, PMN infiltration, pulmonary edema, and hypoxia. To determine whether increased tissue levels of G-CSF contribute to PMN recruitment and PMN-mediated injury, we instilled G-CSF into the lungs by intratracheal injection. Animals treated with G-CSF became hypoxic, hypocapnic, and alkalotic and demonstrated increased BAL fluid cellularity compared with control animals. The wet-to-dry ratio increased significantly after G-CSF instillation and peaked at 12 h. Histological examination of the lungs from G-CSF-treated rats revealed marked edema and increased PMN within the interstitium and alveoli. These results indicate that the presence of G-CSF alone in the lung can lead to recruitment of PMN, lung injury, and impaired pulmonary function, suggesting that local production of G-CSF may contribute to the development of lung damage and possibly ARDS in the setting of resuscitated hemorrhagic shock.

A target fibre study on seats in public houses

A target fibre survey was conducted to assess the random occurrence of a blue wool fibre on seats in public houses throughout the United Kingdom. Fibre tape lifts were taken from 80 seats. Four seats yielded matching fibres and five of these were found on one seat. A total of 292 fibres were identified; nine fibres proved indistinguishable from the target after comparison microscopy, microspectro-photometry and attempts at thin layer chromatography, and two of these fibres were still apparently indistinguishable after TLC analysis although only one dye component was visible.

Hemorrhagic shock induces G-CSF expression in bronchial epithelium

Hemorrhagic shock (HS) initiates a series of inflammatory processes that includes the activation of polymorphonuclear granulocytic neutrophils (PMN). We tested the hypothesis that HS induces granulocyte colony-stimulating factor (G-CSF), a cytokine that augments PMN effector functions, in the lungs of rats. Sprague-Dawley rats were subjected to compensated or decompensated HS followed by resuscitation and death at 4 or 8 h. Animals subjected to HS demonstrated acute lung injury with PMN infiltration, edema, and hypoxia. Using semiquantitative reverse transcriptase-polymerase chain reaction, we detected a 1.9- to 7.1-fold increase in G-CSF mRNA levels in the lung of animals subjected to HS compared with sham controls. Levels of G-CSF mRNA increased with increased duration of the ischemic phase of resuscitated shock. In situ hybridization revealed that bronchoepithelial cells were the major cellular site of G-CSF mRNA. Thus production of G-CSF mRNA by bronchoepithelial cells is dramatically increased in a rat model of HS that also demonstrated lung injury. Increased local G-CSF levels may contribute to PMN recruitment and activation and resultant lung injury in HS.

Pharmacokinetic profile of ABELCET (amphotericin B lipid complex injection): combined experience from phase I and phase II studies

Amphotericin B (AmB) has been the most effective systemic antifungal agent, but its use is limited by the dose-limiting toxicity of the conventional micellar dispersion formulation (Fungizone). New formulations with better and improved safety profiles are being developed and include ABELCET (formerly ABLC), but their dispositions have not been well characterized; hence, the reason for their improved profiles remains unclear. This report details the pharmacokinetics of ABELCET examined in various pharmacokinetic and efficacy studies by using whole-blood measurements of AmB concentration performed by high-pressure liquid chromatography. The data indicated that the disposition of AmB after administration of ABELCET is different from that after administration of Fungizone, with a faster clearance and a larger volume of distribution. It exhibits complex and nonlinear pharmacokinetics with wide interindividual variability, extensive distribution, and low clearance. The pharmacokinetics were unusual. Clearance and volume of distribution were increased with dose, peak and trough concentrations after multiple dosings increased less than proportionately with dose, steady state appeared to have been attained in 2 to 3 days, despite an estimated half-life of up to 5 days, and there was no evidence of significant accumulation in the blood. The data are internally consistent, even though they were gathered under different conditions and circumstances. The pharmacokinetics of ABELCET suggest that lower concentrations in blood due to higher clearance and greater distribution may be responsible for its improved toxicity profile compared to those of conventional formulations.

Chronic ethanol promotes the neuronal differentiation of NG108-15 cells independently of toxin-sensitive G-proteins

The ability of ethanol to promote neuronal differentiation of NG108-15 mouse neuroblastoma x rat glioma hybrid cells was investigated using morphological, biochemical and electrophysiological techniques. Ethanol concentration-(10-200 mM) and time-(1 h-3 days) dependently reduced cell proliferation, but increased acetylcholinesterase (AChE) activity and cell protein content. Chronic ethanol (200 mM) also time-dependently increased voltage-sensitive Ca(2+) currents in the cells. Similar effects were obtained with chronic treatment of the cells with the standard differentiating agents sodium butyrate or forskolin. Chronic treatment of NG108-15 cells with primary alcohols (0.1-200 mM) of varying chain length all reduced cell proliferation and increased cell protein content and AChE activity with the potency order butanol>propanol>ethanol>methanol. Chronic treatment of NG108-15 cells with cholera toxin (50 ng ml(-1)) or pertussis toxin (50 ng ml(-1)) did not induce differentiation of the cells, nor did it modify the effects of 50 or 200 mM ethanol on cell proliferation, AChE activity or cellular protein content. Chronic cholera toxin did however abolish agonist-stimulated adenylyl cyclase activity in the cells, whereas pertussis toxin abolished receptor-mediated inhibition of adenylyl cyclase activity. Furthermore, inhibitors of protein kinase C (GF 109203X, 5 μM), protein kinase A (H-89, 10 μM) or Ca(2+)/calmodulin-dependent protein kinase II (KN-62, 3 μM) all failed to modify the effects of 200 mM ethanol on cell proliferation, AChE activity and cellular protein content. These experiments indicate that chronic ethanol is able to promote neuronal differentiation of NG108-15 cells independently of toxin-sensitive G-proteins and some protein kinases.

A dominant negative mutant of the G protein-coupled receptor kinase 2 selectively attenuates adenosine A2 receptor desensitization

G protein-coupled receptor kinases (GRKs) are thought to be important in mediating the agonist-induced phosphorylation and consequent desensitization of G protein-coupled receptor responses. NG108-15 mouse neuroblastoma X rat glioma cells express a wide range of G protein-coupled receptors and significant levels of GRK2. Therefore, to determine the role of GRK2 in agonist-induced desensitization of various G(s)-coupled receptors in NG108-15 cells, we stably transfected cells with a dominant negative mutant GRK2 construct (Lys220Arg). In homogenates prepared from cells overexpressing the dominant negative mutant GRK2, the acute stimulation of adenylyl cyclase by various receptor and nonreceptor agonists was the same as in control cells stably transfected with plasmid only. NG108-15 cells express both A2a and A2b adenosine receptors, which mediate activation of adenylyl cyclase, with both of these responses being subject to agonist-induced desensitization with a t1/2 of 15-20 min. In dominant negative mutant GRK2 cells, the rates of desensitization of A2a and A2b receptor-stimulated adenylyl cyclase were markedly slower than in plasmid transfected controls, with the latter being similar to wild-type cells. After a 20-min treatment with an adenosine agonist, the desensitization of A2a and A2b receptor-stimulated adenylyl cyclase in dominant negative mutant GRK2 cells was less than half that seen in plasmid transfected control cells. On the other hand, the agonist-induced desensitization of secretin and IP-prostanoid receptor-stimulated adenylyl cyclase was the same in dominant negative mutant GRK2 cells as in plasmid transfected control cells. These results indicate that in intact cells, GRK2 may mediate the desensitization of adenosine A2 receptors. Furthermore, there seems to be selectivity of GRK2 action between G(s)-coupled receptors because the agonist-induced desensitization of secretin and IP-prostanoid receptor-stimulated adenylyl cyclase was not affected by dominant negative mutant GRK2 overexpression.

Development of Strategies to Identify the Learning Needs of Baccalaureate Nursing Students

Meeting the learning needs of nursing students today requires a shift in paradigms and the use of multimethods of teaching. This article describes case-control research undertaken to measure the effects of learning strategies on the final grades of first semester junior level, baccalaureate nursing students. The strategies used and how the students learned to use the strategies are presented. Research results did not provide statistical significance because of the small sample size. However, several trends related to ethnicity, student age, and the content of nursing courses were found. These findings suggest the need for further nursing education research in the areas of information processing and the use of learning strategies within academic and clinical settings.

Ultrasonographic guidance for needle biopsy of breast lesions

The use of imaging-guided needle biopsies of the breast to establish the histology of lesions has become an important tool in the clinical management of breast pathology. Avoiding excision of benign lesions and allowing definitive surgery of malignant lesions to be planned from the outset are to the benefit of the patient and also decrease the cost of breast health care. The use of ultrasonographic guidance for such procedures provides a safe and effective real time technique to sample tissue while the patient lies in a comfortable supine position. The operator who has a good understanding of the procedure will be able to obtain reliable specimens efficiently and consistently.

Physiologic and molecular characterization of the role of nitric oxide in hemorrhagic shock: evidence that type II nitric oxide synthase does not regulate vascular decompensation

To determine the role of nitric oxide (NO) in decompensated and irreversible hemorrhagic shock, rats were subjected to hemorrhagic shock (HS) for 3 or 5 h. Lung, liver, and plasma samples were studied for evidence of NO formation using Northern analysis and immunohistochemistry for Type II NOS, as well as measurement of plasma nitrite/nitrate, cyclic GMP, and nitrosylated hemoglobin levels. Comparisons were made with similarly instrumented time-matched sham rats. Type II NOS mRNA and protein were detectable in lung and liver only in the irreversible phase of HS (5 h). A large accumulation of nitrosylated hemoglobin and nitrite/nitrate appeared in the irreversible phase. Significant accumulation of cyclic GMP or nitrite/nitrate was not detectable in the decompensation phase. Despite the hemodynamic decompensation at 3 h of HS, Type II NOS mRNA and protein expression, as well as NO metabolites were not elevated. To assess whether NO plays a physiologically significant role in decompensation, rats in the decompensation phase and sham animals were subjected to nonspecific NOS inhibition. Both groups displayed a similar magnitude and duration of blood pressure elevation. Hemodynamic decompensation in HS is not mediated by Type II NOS induction. NO production increases only after prolonged HS; significant NO production is observed only in severe, irreversible HS.

Granulocyte colony-stimulating factor (G-CSF) production in hemorrhagic shock requires both the ischemic and resuscitation phase

Granulocyte colony-stimulating factor (G-CSF) is the cytokine that is critical for polymorphonuclear neutrophilic granulocyte (PMN) production as well as being a potent agonist of PMN activation. We have recently reported that in the lung and the liver of rats resuscitated after hemorrhagic shock (HS) G-CSF mRNA expression is induced. It is not known if both phases of HS, the ischemic and the reperfusion phase, are required for G-CSF mRNA induction. The present study was designed to test the hypothesis that the upregulation of G-CSF mRNA expression is the consequence of HS followed by resuscitation and that ischemia alone is insufficient to induce G-CSF mRNA expression in the affected organs. Male Sprague-Dawley rats were subjected to resuscitated and unresuscitated shock protocols of varying severity. Control animals were subjected to anesthesia and all surgical preparations except for hemorrhage. Lungs and livers were isolated and their RNA extracted. Using semiquantitative reverse transcriptase-polymerase chain reaction (RT-PCR), we demonstrated that G-CSF mRNA was induced in the lung and liver of shock animals above the level observed in control animals. Upregulation of G-CSF mRNA relative to controls occurred only in animals undergoing resuscitated HS and not in ones subjected to unresuscitated HS. These results indicate that G-CSF production specific for the hemorrhage component of shock is dependent on resuscitation. As a consequence, the production of this cytokine may be decreased through modifications in the resuscitation protocols.

Effect of the potassium channel opener ZM260384 on skeletal muscle function during restricted blood flow in the anaesthetized cat

The aim of the present experiment was to determine whether the potassium channel opener 2-(2,2-bis(difluoromethyl)-6-nitro-3,4-dihydro-2H-1, 4-benzoxazine-4-yl)pyridine-N-oxide (ZM260384) was capable of accelerating the decline in skeletal muscle function during restricted blood flow in vivo. Cats (3.0-4.5 kg body weight) were anaesthetized with alphaxalone-alphadalone and breathed spontaneously following tracheotomy. Isometric tension was measured in the extensor digitorum longus-anterior tibialis (EDL-TA) muscle group. Ischaemia was induced by perfusing the hindlimb with the animal's own blood at a rate of 12.5 ml min-1 using a roller pump and stimulating the common peroneal nerve to induce repetitive submaximal tetanic contractions in the EDL-TA. The number of stimulation voltage increments required each minute to maintain a constant level of submaximal mechanical output and the time to exhaustion were used as indices of the rate of tension decline. The rate of tension decline in the ischaemic EDL-TA in the presence of ZM260384 at 3 mg kg-1, a maximally hypotensive dose predicted to be within the dose range required to exert direct effects on skeletal muscle, was measured and compared with the rate of tension decline in the presence of ZM260384 at 0.03 mg kg-1, also maximally hypotensive dose but below the predicted dose range for skeletal muscle effects. The number of voltage increments per minute was 1.93 +/- 0.07 and 1.48 +/- 0.14 (P < 0.05) in the presence of 3 and 0.03 mg kg-1 ZM260384, respectively. Time to exhaustion was 17.5 +/- 4.2 and 7.2 +/- 0.8 min (P < 0.05) in the presence of 3 and 0.03 mg kg-1 ZM260384, respectively. Given that there was no difference between these two groups in any haemodynamic variable measured, the results of the present study suggest that ZM260384 (3 mg kg-1) increases the rate of isometric force loss in ischemic skeletal muscle in vivo.

Does vitamin C cause hemolysis in premature newborn infants? Results of a multicenter double-blind, randomized, controlled trial

OBJECTIVE

We tested the hypothesis that vitamin C supplementation of premature neonates is associated with hemolysis.

STUDY DESIGN

A double-blind, randomized, controlled trial of vitamin C supplementation (50 mg/day) was undertaken in premature neonates (birth weight, 1000 to 1500 gm). Infants were randomly assigned to receive vitamin C (Ce-Vi-Sol) (n = 32) or placebo (n = 24) for 14 days. Twenty-three subjects per group were required to detect a difference of 1 SD in corrected carboxyhemoglobin values (alpha = 0.05, beta = 0.10).

RESULTS

Day 14 vitamin C levels were lower in control subjects than in supplemented neonates (62 +/- 24 vs 125 +/- 62 micromol/L, p = 0.005). There was no difference in corrected blood carboxyhemoglogin concentrations (0.72 +/- 0.44 vs 0.72 +/- 0.23%; p = 0.95), other parameters of hemolysis, weight gain, blood sampled, presumed septic episodes, necrotizing enterocolitis, feeding intolerance, or transfusion. On day 14, bilirubin values were higher in control subjects than in the supplemented group (77 +/- 37 vs 55 +/- 33 micromol/L; p = 0.04). When a distant outlier in the nonsupplemented group was excluded (163 micromol/L), statistical significance was lost (73 +/- 32 vs 55 +/- 33 micromol/L; p = 0.09).

CONCLUSION

Oral supplementation of premature infants with vitamin C is not associated with evidence of increased erythrocyte destruction, hyperbilirubinemia, or other morbidity.

Metallothionein and HSP-72 are induced in the liver by hemorrhagic shock and resuscitation but not by shock alone

BACKGROUND

Previous reports have indicated that HSP-72 and metallothionein mRNA undergo induction in the liver after resuscitated hemorrhagic shock. In this study we investigated whether unresuscitated shock triggers induction and whether protein induction also occurs.

METHODS

Rats were subjected to resuscitated and unresuscitated shock protocols of varying severity; livers were isolated and processed for Northern, Western, and immunohistochemical analysis. Cadmium binding assay was used to measure metallothionein protein.

RESULTS

Unresuscitated shock led to no induction of HSP-72 or metallothionein. Severe resuscitated shock led to prompt induction of HSP-72 mRNA and protein in hepatocytes, up to 20-fold over sham group; metallothionein mRNA induction appeared later than HSP-72 and did not lead to elevated protein levels. Mild resuscitated shock had little effect.

CONCLUSIONS

These findings indicate resuscitated severe shock, not shock alone, leads to induction of HSP-72 and metallothionein in the liver. Metallothionein expression lags behind HSP-72 expression.

Cytomegalovirus infections in Toronto child-care centers: a prospective study of viral excretion in children and seroconversion among day-care providers

OBJECTIVES

To prospectively determine the rate of cytomegalovirus shedding in children and the rate of seroconversion to cytomegalovirus in providers at 38 infant-toddler day care centers in Toronto, Canada.

METHODS

Urine was collected for shell vial assay in 471 children between the ages of 3 and 42 months. Providers (n = 206) were tested for the presence of cytomegalovirus antibody by latex agglutination. Of the 68 providers who were seronegative, 56 were retested approximately 1 year later.

RESULTS

Viruria was documented in 79 (17%) children and antibody in 67% of providers. Seropositivity was significantly related to country of birth outside Canada, presence of children at home < 5 years of age and increased household size. Seroconversion was documented in 12.5% (n = 7). Of these providers 71% worked at centers where workers never wore gloves for diaper changing vs. 33% of those who did not seroconvert (P = 0.06), and all were younger than 30 years vs. 59% of those who did not seroconvert (P = 0.04). In centers with viruria the association of seroconversion with lack of glove use was enhanced (P = 0.04). Seroconversion was marginally more likely in providers working with infants only than with infants and toddlers or with toddlers alone. Logistic regression confirmed that seroprevalence was more likely in providers who were born outside Canada, had children younger than age 5 years in the household and with an increased number of people in the household. Seroconversion was more likely if the provider worked at centers not using gloves for diaper changes, worked with infants only rather than with toddlers and infants and was < 30 years old, with each factor contributing independently to the model.

CONCLUSIONS

Cytomegalovirus infection is common in children and providers in Toronto day-care centers.

Laparoscopic cholecystectomy in the transplant population

BACKGROUND

The results of laparoscopic cholecystectomy in a group of transplant recipients were reviewed to determine the safety and efficacy of the procedure in the setting of immunosuppression.

METHODS

All solid-organ-transplant recipients who underwent laparoscopic cholecystectomy over a 3-year period were reviewed. Indication for operation, conversion to open procedure, length of stay, and complications were characterized. These results were compared to the registry data of all laparoscopic cholecystectomies performed at the same institution.

RESULTS

There were 26 transplant patients who underwent laparoscopic cholecystectomy including renal, heart, double lung, and heart-lung recipients. The mean age was 47 years. Symptomatic cholelithiasis was the most common indication in 73% of patients followed by acute cholecystitis in 11%. Seven patients (27%) underwent conversion to an open procedure. Three patients (11.5%) experienced a minor complication in hospital. Median length of stay was 2.5 days. One patient died during a subsequent unrelated operation. These results compared favorably to the registry experience at the same institution where the mean age was 49 years, 24% of cases were performed for acute cholecystitis, there was a 10% complication rate, median length of stay was 2 days, and 3 deaths occurred in hospital. The only statistically significant difference was a lower conversion rate (11% vs 27%) in the registry vs transplant group.

CONCLUSIONS

This experience confirms that laparoscopic cholecystectomy is as safe in the transplant population as the general population. Despite a slightly higher conversion rate to an open procedure, the advantages of short hospital stay, low morbidity, and early return to preoperative routines remain equivalent.

The effects of pharmacological modulation of KATP on the guinea-pig isolated diaphragm

The purpose of the present study was to investigate the functional consequences of KATP modulation in the normal and the metabolically inhibited guinea-pig isolated diaphragm using the K+ channel openers cromakalim, pinacidil, RP49356 (N-methyl-2-(3-pyridil)-tetrahydrothiopyran-2-carbothiami de-1-oxide) and ZM260384 (2-(2,2-bis(difluoromethyl)-6-nitro-3,4-dihydro-2H-1,4-benzoxazine -4-yl)pyridine-N-oxide) and the K+ channel inhibitors glibenclamide, phentolamine and ciclazindol. All K+ channel openers accelerated the decline in function induced by intermittent tetanic contractions following metabolic inhibition and delayed the development of contracture. Cromakalim also improved the recovery of twitch tension following 10 min intermittent tetanic stimulation in the hypoxic guinea-pig diaphragm preparation. Of the K+ channel inhibitors tested, only ciclazindol, at the highest concentration tested (10 microM), significantly delayed the decline in tetanic tension following metabolic inhibition in the guinea-pig isolated diaphragm. None of the inhibitors significantly accelerated the development of contracture. All inhibitors however, antagonised the actions of the K+ channel opener, cromakalim. The results indicate that opening of KATP can accelerate the decline in function following metabolic inhibition in the guinea-pig isolated diaphragm. In the absence of K+ channel openers however, KATP does not appear to contribute to this decline under the conditions of the present study.

Hemorrhagic shock

A great deal has been learned about the pathophysiologic condition of hemorrhagic shock. The response of the hormonal and inflammatory mediator systems in patients in hemorrhagic shock appears to represent a distinct set of responses different from those of other forms of shock. The classic neuroendocrine response to hemorrhage attempts to maintain perfusion to the heart and brain, often at the expense of other organ systems. This intense vasoconstriction occurs via central mechanisms. The response of the peripheral microcirculation is driven by local tissue hypoperfusion that results in vasodilation in the ischemic tissue bed. Activation of the systemic inflammatory response by hemorrhage and tissue injury is an important component of the pathophysiologic condition of hemorrhagic shock. Activators of this systemic inflammatory response include ischemia/reperfusion injury and neutrophil activation. Capillary "no-flow" with prolonged ischemia and "no-reflow" with reperfusion may initiate neutrophil activation in patients in hemorrhagic shock. The mechanisms that lead to decompensated and irreversible hemorrhagic shock include (1) "arteriolar hyposensitivity" as manifested by progressive arteriolar vasodilation and decreased responsiveness of the microcirculation to alpha-agonists, and (2) cellular injury and activation of both proinflammatory and counterinflammatory mechanisms. These changes represent a failure of the microcirculation. Redistribution of cardiac output and persistent gut ischemia after adequate resuscitation may also contribute to the development of irreversible hemorrhagic shock. Treatment of hemorrhagic shock includes rapid operative resuscitation to limit activation of the mediator systems and abort the microcirculatory changes that result from hemorrhagic shock. Volume resuscitation and control of hemorrhage, should occur simultaneously. The end point in volume resuscitation of hemorrhagic shock must be maintenance of organ system and cellular function. Whether we use adequate urine output, correction of lactic acidemia, optimization of oxygen delivery, or oxygen consumption as our specific goal, the general objective is to provide adequate crystalloid solution and packed red blood cells to achieve and maintain normal organ and cellular perfusion and function.

Nitric oxide, sepsis, and arginine metabolism

Nitric oxide is one of the most versatile molecules produced by mammalian cells. Its role in sepsis and inflammation has been the subject of intense investigation since its discovery as a cell product in 1987. The role of arginine in sepsis and trauma has also received considerable attention, but most of the earlier studies on arginine preceded the studies on nitric oxide and the discovery that arginine serves as the nitrogen donor for nitric oxide synthesis. This review will explore the role that nitric oxide plays in sepsis and the effects of arginine metabolism on nitric oxide synthesis.

Effects of acute and chronic ethanol on cyclic AMP accumulation in NG108-15 cells: differential dependence of changes on extracellular adenosine

1. This study investigated the effects of acute and chronic ethanol on basal, agonist- and forskolin-stimulated cyclic AMP formation in NG108-15 mouse neuroblastoma x rat glioma hybrid cells, and examined the role of changes in extracellular adenosine concentrations on the effects observed. 2. NG108-15 cells incubated acutely with ethanol (1-200 mM) displayed concentration-dependent increases in basal and iloprost-stimulated (300 nM; a prostanoid IP receptor agonist) cyclic AMP accumulation but a concentration-dependent decrease in forskolin-stimulated (10 microM) accumulation. 3. Cells treated chronically with ethanol (200 mM) for 48 h displayed increases over control in basal, iloprost- (0.001-10 microM) and forskolin (0.01-100 microM)-stimulated cyclic AMP formation. However, chronic ethanol did not affect [3H]-iloprost binding to cell membranes. 4. Inclusion of adenosine deaminase (ADA; 1 unit ml-1) during the incubation period to measure cyclic AMP accumulation completely abolished the increase in basal accumulation following chronic ethanol, but did not affect the increase in iloprost stimulation. On the other hand ADA partially reversed the increase in forskolin stimulation following chronic ethanol, but even in the presence of high concentrations of ADA (5 units ml-1) the forskolin stimulation remained elevated above control. 5. Cells treated chronically with the adenosine receptor agonist 5'-(N-ethylcarboxamido)-adenosine (NECA; 10 microM for 48 h) displayed a reduction in subsequent NECA- and forskolin-stimulated cyclic AMP accumulation, but iloprost stimulation was not affected. ADA included acutely during the incubation period to measure cyclic AMP accumulation abolished the reduction in forskolin but not NECA stimulation produced by the chronic NECA pretreatment. 6. We have previously noted that ethanol inhibits NG108-15 cell proliferation and alters cell morphology.To mimic this, cells were incubated in the absence of foetal calf serum for 48 h. Following this time, basal, iloprost- and forskolin-stimulated cyclic AMP formation was enhanced over that in cells grown in the presence of serum.7. These results indicate that chronic ethanol enhances cyclic AMP formation in intact NG108-15 cells by more than one mechanism: one involves increased extracellular adenosine concentrations and the other a change in the transduction system beyond the receptor, possibly involving the adenylyl cyclase enzyme. Furthermore the ethanol-induced changes in cyclic AMP accumulation may relate to alterations in NG108-15 cell growth and development.

Tuberculin sensitivity and the BCG scar in tuberculosis contacts

SETTING

Tuberculosis clinic, St Vincents Hospital, Dublin.

OBJECTIVE

To determine the influence of past BCG vaccination on tuberculin sensitivity in tuberculosis contacts.

DESIGN

Prospective cohort study of tuberculin sensitivity using the Mantoux technique (5 TU).

RESULTS

In 1050 contacts of 96 cases of tuberculosis, BCG scars were noted in 76% of the contacts. Approximately 50%, 30% and 20% of the contacts respectively had negative (0-4 mm), positive (5-14 mm) and strongly positive (15+ mm) Mantoux responses. The presence of a BCG scar was not found to significantly influence the degree of tuberculin sensitivity. The degree of tuberculin sensitivity increased after 20 years and decreased after 60 years of age. Contacts of sputum-positive cases of tuberculosis had larger Mantoux responses.

CONCLUSIONS

The study suggests that age of the contact and sputum status of the index case are important determinants of the degree of tuberculin sensitivity. Attributing a 'positive' Mantoux response to past BCG vaccination may be encouraging a false sense of security in contacts recently exposed to an infectious case of tuberculosis. Contact management guidelines may need to be reviewed and perhaps modified to reflect this finding.

Inhibition of ADP-ribosyltransferase increases synthesis of Gs alpha in neuroblastoma x glioma hybrid cells and reverses iloprost-dependent heterologous loss of fluoride-sensitive adenylate cyclase

Exposure of NG108-15 cells to 50 mM nicotinamide [an inhibitor of mono(ADP-ribosyl)transferase] for 18 hr led to an increase in membrane associated Gs alpha measured either as cholera toxin substrate or by immunoblotting with a specific antiserum. Prolonged exposure of NG108-15 cells to iloprost is followed by homologous loss of iloprost sensitivity, and heterologous loss of fluoride-dependent activation of adenylate cyclase. Nicotinamide reversed the loss of fluoride sensitivity, but failed to restore iloprost-dependent activation of adenylate cyclase. These results with nicotinamide in NG108-15 cells contrasted with those from platelets, which also exhibit heterologous desensitization of fluoride sensitivity following prolonged exposure to iloprost. Treatment of platelets with 50 mM nicotinamide for 18 hr led to an increase of 75.0 +/- 19.4% in the amount of membrane associated cholera toxin substrate. However, there was no associated increase in the abundance of Gs alpha as determined by immunoblotting. Furthermore, in platelets there was no restoration by nicotinamide of the iloprost-dependent loss of fluoride-sensitive adenylate cyclase activity. It follows that heterologous desensitization in platelets is accompanied by inactivation of Gs alpha, which is retained within the plasma membrane in its inactive state. The nicotinamide-dependent increase in the abundance of membrane associated cholera toxin substrate and immunoreactive Gs alpha in NG108-15 cells is associated with an increase of 72.0 +/- 20.3% in the levels of mRNA encoding Gs alpha. The capacity of nicotinamide to increase the abundance of membrane associated Gs alpha was reversed when the cells were cultured in the presence of 20 micrograms/mL cycloheximide. These results suggest that the ability of nicotinamide to increase the abundance of Gs alpha in NG108-15 cells is mediated by de novo protein synthesis.

Methodological issues in patient satisfaction surveys

Examines some of the methodological problems encountered in conducting patient satisfaction surveys, including the sampling frames, quality of survey data and instruments, non-response problems, and reporting and interpretation of results. Proposes guidelines and lays out an agenda for future research.