Effects of external pH on ionic currents in smooth muscle cells from the basilar artery of the guinea pig.

pHo is an important determinant of vascular tone in cerebral blood vessels. We investigated the effects of changes in pHo on isolated smooth muscle cells from the basilar artery of the guinea pig. Single cells contracted rapidly in response to an elevation in pHo (constant CO2), and contraction was blocked by nifedipine, suggesting a role for dihydropyridine-sensitive Ca2+ channels. In whole-cell patch-clamp experiments, changes in pHo (pHo 5.7-8.1, pHi 7.2 with 10 mM HEPES) strongly affected the amplitude of the peak Ca2+ channel current (10 mM Ba2+, +15 mV, holding potential of -55 mV), with an apparent pK of 6.9. The current-voltage curves were minimally shifted, indicating no important effect of surface charge. To separate the slowly inactivating L-type Ca2+ channel current from the more rapidly inactivating B-type current, the decaying portions of inward currents from cells studied with repetitive 1-second pulses (+15 mV, holding potential of -55 mV) were fit to a two-component model. Titration curves for the L-type and B-type currents indicated maximum increases by factors of 3.65 and 1.28 at alkaline pHo and gave apparent pK values of 7.71 and 6.47 (Hill coefficient unity). The time constant of inactivation for the B-type current at +15 mV was little affected by pHo, whereas that for the L-type current increased somewhat with increasing pHo. Additional experiments showed no significant effect of pHo on holding current or on voltage-activated outward currents (pCai 7 with 11 mM EGTA). Our results provide additional evidence for participation of Ca2+ channels in regulating basal tone in cerebral smooth muscle and indicate that pHo regulates current through slowly inactivating, dihydropyridine-sensitive L-type Ca2+ channels.     

Functional integrity of endothelium determines Ca2+ channel availability in smooth muscle: involvement of nitric oxide

Endothelium regulates smooth muscle contractility in part via nitric oxide (NO). We tested the hypothesis that endothelial dysfunction, either produced by injury or simulated pharmacologically by reducing the bioavailability of NO, results in elevated Ca2+ channel availability (ngmax=maximum conductance/cell capacitance) in smooth muscle cells isolated from the vessel. Using basilar arteries of normotensive Wistar rats, we measured ngmax in smooth muscle cells from control vessels, from vessels in which endothelium was injured using Na fluoroscene plus light, and from vessels in which the bioavailability of NO was reduced by pretreatment with the NO scavenger 1H-imidazol-1 -yloxy,2-(4-carboxyphenyl)-4,5-dihydro-4,4,5,5-tetramethyl-3-oxide , potassium salt (C-PTIO), or the endothelial nitric oxide synthase (eNOS) inhibitor N(G)-nitro-L-arginine methyl ester (L-NAME). Values of ngmax in these four groups of cells were 0.28+/-0.02 nS/pF (n=22), 0.51+/-0.05 nS/pF (n=15), 0.430+/-.03 nS/pF (n=12), and 0.47+/-0.04 nS/pF (n=14) (P<0.05, ANOVA), respectively. To determine whether larger currents associated with endothelial dysfunction exhibit altered sensitivity to exogenous NO, we quantified the response to various concentrations of NO donor, Na nitroprusside (SNP), in 37 cells from control vessels and 33 cells from vessels pretreated with L-NAME. SNP exhibited identical potency (half-maximum values, 18.7 and 21.1 nM) but greater apparent efficacy (maximum fractional block, 0.82 versus 0.63) in down-regulating Ca2+ channel currents in cells isolated from vessels with dysfunctional endothelium. Our results are consistent with a direct influence of endogenous NO on Ca2+ channel availability in smooth muscle cells, and indicate that Ca2+ channel availability in isolated smooth muscle cells may be a sensitive measure of the functional integrity of the endothelium in the parent vessel.     

Comparison of caprine,human and bovine strains of respiratory syncytial virus

Summary A new continuous ovine kidney cell line allowing the growth of caprine, human and bovine respiratory syncytial virus was used to minimize host cell related variations for the direct comparison of the viral ultrastructures, serological relationships and structural protein profiles. Results show that all three strains are closely related although a closer relationship was found between bovine and caprine RS.     

Sodium nitroprusside and cGMP decrease Ca2+ channel availability in basilar artery smooth muscle cells

 We studied the effect of the nitric oxide (NO) donor, sodium nitroprusside (SNP), on the macroscopic and single-channel currents due to the 22-pS Ca²⁺ channel in smooth muscle cells from guinea pig basilar artery. In nystatin-perforated whole-cell recordings, 50 nM SNP decreased the macroscopic current to 63±12% of control values, without changing the voltage dependence of the current. In cell-attached patches with BAY-K8644 in the pipette, SNP caused a comparable decrease in single-channel availability (n ·P _o) that was dose dependent over the range of 10 nM to 10 μM SNP. SNP had no effect on single-channel properties, including slope conductance, voltage dependence of activation, the number of open states, the time constants of the open states, and the proportion of time spent in each open state. The effect of SNP (50 nM) on single Ca²⁺ channel openings was reproduced by 8-Br-cGMP (100 μM), which also reduced channel availability without altering channel properties. The protein kinase inhibitor H-8 (1.5 μM), which exhibits relative specificity for cGMP-dependent protein kinase, completely inhibited the decrease in single-channel availability expected with SNP. The dose-dependent decrease in Ca²⁺ channel availability caused by SNP was not altered by prior application of 8-Br-cAMP or forskolin, both of which cause an increase in Ca²⁺ channel availability in these cells. Our findings suggest that NO decreases openings of Ca²⁺ channels in basilar artery smooth muscle cells without altering channel properties, and that it does so by a mechanism likely to involve cGMP-dependent protein kinase. Received: 2 July 1996 / Received after revision: 30 September 1996 / Accepted: 2 October 1996     

Linkage disequilibrium analysis of childhood-onset spinal muscular atrophy (SMA) in the French -- Canadian population

Spinal muscular atrophy (SMA) is, after Duchenne muscular dystrophy,the most common neuromuscular disorder in childhood. The generesponsible for childhood SMA has been mapped to the q11. 2– q13. 3 region of chromosome 5. We have extended ourlinkage studies of SMA In the French - Canadian population toInclude microsatellite markers at the D5S125, D5S351, D5S435,JK53CA1/ 2 and MAPI B locl. These markers span about 4 cM ofthe SMA candidate region. We observed significant evidence forlinkage between SMA and all the markers tested. The analysisof recombinant chromosomes provide evidence for the followinggenetic order: D5S125-D5S435-MAP1B-3'-JK53CA1/2 and places D5S351proximal to JK53CA1/2. Furthermore, we confirm the current localizationof the SMA gene distal to D5S435. Finally, we provide demonstrationof significant linkage disequilibrium between childhood-onsetSMA and four of the five marker loci, D5S125, D5S435, D5S351and JK53CA1/2. Analysis of SMA-region haplotypes suggests thatthere may be a predominant SMA allele that is present on about17% of SMA chromosomes in this sample of the French - Canadianpopulation. We conclude that the observed linkage disequilibriumis likely due to genetic drift among regions of Quebec, consistentwith this population's early history.     

Upper eyelid movements measured with a search coil during blinks and vertical saccades.

Upper eyelid movements were recorded in nine human subjects by mounting a miniature coil of wire directly on the eyelid and subjecting the search coil to a vertically directed alternating magnetic field. The metrics of blinks and lid movements accompanying saccades were described by "main sequence" relationships, linking maximum velocity to amplitude and duration to amplitude. In general, lid movements were faster than those reported previously in the literature, but there was considerable intersubject variability. On average, the main sequence relationships for blinks were independent of either starting lid position or whether the blinks were generated spontaneously, reflexively, or voluntarily. For the down phase of the average blink, both the maximum velocity and duration increased almost linearly with amplitude. The maximum velocity of the down phase was faster than that of the up phase. For lid movements accompanying vertical saccades, the maximum velocities in the up and down directions were similar and increased nonlinearly with amplitude, saturating at about 120 mm/sec (approximately 450 degrees/sec). Duration increased approximately linearly with amplitude. The down phases of blinks were much faster than those of saccade-related lid movements. By comparison, the maximum velocities of the up phase of blinks and of saccade-related lid movements were almost equal. The large intersubject variability suggests caution when using normative data to interpret abnormal lid motion for clinical purposes.     

Oxidative enzyme activities of the vastus lateralis muscle and the functional status in patients with COPD

BACKGROUND: Enzymatic and histochemical abnormalities of the peripheral muscle may play a role in exercise intolerance in patients with chronic obstructive pulmonary disease (COPD). A study was undertaken to measure the mitochondrial enzyme activity of the vastus lateralis muscle in patients with COPD and to evaluate the relationship between enzyme activities and functional status. METHODS: Fifty seven patients with COPD of mean (SD) age 66 (7) years with forced expiratory volume in one second (FEV(1)) 39 (15)% predicted and peak oxygen uptake (VO(2)) of 14 (4) ml/min/kg and 15 normal subjects of similar age were included in the study. Each subject performed a stepwise exercise test up to maximal capacity during which five-breath averages of VO(2) were measured. Muscle specimens were obtained by percutaneous needle biopsy of the vastus lateralis muscle and the activity of two mitochondrial enzymes (citrate synthase (CS) and 3-hydroxyacyl CoA dehydrogenase (HADH)) was measured. The functional status of the patients was classified according to peak VO(2). RESULTS: CS and HADH activities were markedly reduced in patients with COPD compared with normal subjects (22.3 (2.7) versus 29.5 (7.3) micromol/min/g muscle (p<0.0001) and 5. 1 (2.0) versus 6.7 (1.9) micromol/min/g muscle (p<0.005), respectively). The activity of CS decreased progressively with the deterioration in the functional status while that of HADH was not related to functional status. Using a stepwise regression analysis, percentage predicted functional residual capacity (FRC), the activity of CS, oxygen desaturation during exercise, age, and inspiratory capacity (% pred) were found to be significant determinants of peak VO(2). The regression model explained 59% of the variance in peak VO(2) (p<0.0001). CONCLUSIONS: The oxidative capacity of the vastus lateralis muscle is reduced in patients with moderate to severe COPD compared with normal subjects of similar age. In these individuals the activity of CS correlated significantly with peak exercise capacity and independently of lung function impairment.     

Pulmonary lymphangiectasia revisited

PURPOSE: Pulmonary lymphangiectasia (PL) is a rare, poorly documented disease characterized by abnormal pulmonary lymphatics. Although case reports are published, little is known about survivors past the neonatal period. METHODS: This is a retrospective review of histologically proven PL in fetuses, infants, and long term survivors since 1965. RESULTS: Eleven children (8 boys, 3 girls) and 8 aborted fetuses (7 male, 1 female) were identified. The fetuses weighed 463.4 g (177 to 681 g). Six were aborted between 19 to 24 weeks of gestation for multiple malformations or anencephaly, and 2 spontaneously aborted: one with PL only, the other with twin-twin transfusion syndrome. Clinical PL was diagnosed between 0 and 11 months of age. Six children died (2 neonatal, 4 within 10 days), 5 survived. Two deaths occurred after cardiac surgery. Among survivors, the symptomatology and frequency of admissions diminished over time. Symptoms included progressive respiratory distress, chronic cough, recurrent pneumonia, bronchial asthma, and choking. One child with bilateral chylothorax was later diagnosed with Noonan syndrome; 2 patients had minor cardiac malformations. Rapid deterioration occurred with mild respiratory infections with only supportive treatment available. Chest x-ray showed marked hyperinflation with interstitial infiltrate. CONCLUSIONS: This is the first long-term study of primary PL and will help counsel parents. Although fatal in the neonatal period, survival is possible if diagnosed past the neonatal period and improvement is expected.     

Randomized study on the efficacy of cognitive-behavioral therapy for insomnia secondary to breast cancer, part I: Sleep and psychological effects.

PURPOSE: Chronic insomnia is highly prevalent in cancer patients. Cognitive-behavioral therapy (CBT) is considered the treatment of choice for chronic primary insomnia. However, no randomized controlled study has been conducted on its efficacy for insomnia secondary to cancer. Using a randomized controlled design, this study conducted among breast cancer survivors evaluated the effect of CBT on sleep, assessed both subjectively and objectively, and on hypnotic medication use, psychological distress, and quality of life. PATIENTS AND METHODS: Fifty-seven women with insomnia caused or aggravated by breast cancer were randomly assigned to CBT (n = 27) or a waiting-list control condition (n = 30). The treatment consisted of eight weekly sessions administered in a group and combined the use of stimulus control, sleep restriction, cognitive therapy, sleep hygiene, and fatigue management. Follow-up evaluations were carried out 3, 6, and 12 months after the treatment. RESULTS: Participants who received the insomnia treatment had significantly better subjective sleep indices (daily sleep diary, Insomnia Severity Index), a lower frequency of medicated nights, lower levels of depression and anxiety, and greater global quality of life at post-treatment compared with participants of the control group after their waiting period. Results were more equivocal on polysomnographic indices. Therapeutic effects were well maintained up to 12 months after the intervention and generally were clinically significant. CONCLUSION: This study supports the efficacy of CBT for insomnia secondary to breast cancer.