The effect of tezosentan, a non-selective endothelin receptor antagonist, on shear stress-induced changes in arterial diameter of the anaesthetized dog

The effects of changes in the mean ( S _m) and pulsatile ( S _p) components of arterial wall shear stress on arterial dilatation of the iliac artery of the anaesthetized dog were examined in the absence and presence of the endothelin receptor antagonist tezosentan (10 mg kg⁻¹ I.V.; Ro 61-0612; [5-isopropyl-pyridine-2-sulphonic acid 6-(2-hydroxy-ethoxy)-5-(2-methoxy-phenoxy)-2-(2-1 H -tetrazol-5-yl-pyridin-4-yl)-pyrimidin-4-ylamide]). Changes in shear stress were brought about by varying local peripheral resistance and stroke volume using a distal infusion of acetylcholine and stimulation of the left ansa subclavia. An increase in S _m from 1.81 ± 0.3 to 7.29 ± 0.7 N m⁻² (means ± S.E.M.) before tezosentan caused an endothelium-dependent arterial dilatation which was unaffected by administration of tezosentan for a similar increase in S _m from 1.34 ± 0.6 to 5.76 ± 1.4 N m⁻² (means ± S.E.M.). In contrast, increasing the S _p from 7.1 ± 0.8 to a maximum of 11.5 ± 1.1 N m⁻² (means ± S.E.M.) before tezosentan reduced arterial diameter significantly. Importantly, after administration of tezosentan subsequent increases in S _p caused arterial dilatation for the same increase in S _p achieved prior to tezosentan, increasing from a baseline of 4.23 ± 0.4 to a maximum of 9.03 ± 0.9 N m⁻² (means ± S.E.M.;   P < 0.001  ). In conclusion, the results of this study provide the first in vivo evidence that pulsatile shear stress is a stimulus for the release of endothelin from the vascular endothelium.     

Increased glomerular angiotensin II binding in rats exposed to a maternal low protein diet in utero

In the rat, protein restriction during pregnancy increases offspring blood pressure by 20–30 mmHg. We have shown in an earlier study that this is associated with a reduction in nephron number and increased glomerular sensitivity to angiotensin II (Ang II) in vivo . Hence, we hypothesized that exposure to a maternal low-protein diet increases glomerular Ang II AT₁ receptor expression and decreases AT₂ receptor expression. To test this hypothesis, pregnant Wistar rats were fed isocalorific diets containing either 18% (control) or 9% (LP) protein from conception until birth. At 4 weeks of age, the kidneys of male offspring were harvested to measure cortical AT₁ and AT₂ receptor expression, ¹²⁵I-Ang II glomerular binding, tissue renin activity, tissue Ang II and plasma aldosterone concentrations. AT₁ receptor expression was increased (62%) and AT₂ expression was decreased (35%) in LP rats. Maximum ¹²⁵I-Ang II (¹²⁵I-Ang II) binding ( B _max) was increased in LP rats (control n = 9, 291.6 ± 27.4 versus LP n = 7, 445.7 ± 27.4 fmol (mg glomerular protein)⁻¹, P < 0.01), but affinity ( K _D) was not statistically different from controls (control 2.87 ± 0.85 versus LP 0.84 ± 0.20 pmol ¹²⁵I-Ang II, P = 0.059). Renal renin activity, tissue Ang II and plasma aldosterone concentrations did not differ between control and LP rats. Increased AT₁ receptor expression in LP rat kidneys is consistent with greater haemodynamic sensitivity to Ang II in vivo . This may result in an inappropriate reduction in glomerular filtration rate, salt and water retention, and an increase in blood pressure.     

Inward-rectifying anion channels are expressed in the epithelial cells of choroid plexus isolated from ClC-2 'knock-out' mice

Choroid plexus epithelial cells express inward-rectifying anion channels which have a high HCO₃⁻ permeability. These channels are thought to have an important role in the secretion of cerebrospinal fluid. The possible relationship between these channels and the ClC-2  Cl⁻  channel was investigated in the present study. RT-PCR, using specific ClC-2 primers, amplified a 238 bp fragment of mRNA from rat choroid plexus, which was 99 % identical to the 5' sequence of rat ClC-2. A 2005 bp clone was isolated from a rat choroid plexus cDNA library using a probe for ClC-2. The clone showed greater than 99 % identity with the sequence of rat ClC-2. Inward-rectifying anion channels were observed in whole-cell recordings of choroid plexus epithelial cells isolated from ClC-2 knock-out mice. The mean inward conductance was 19.6 ± 3.6 nS (   n = 8  ) in controls (3 heterozygote animals), and 22.5 ± 3.1 nS (   n = 10  ) in three knock-out animals. The relative permeability of the conductances to I⁻ and  Cl⁻  ( P _I : P _Cl) was determined. I⁻ was more permeant than  Cl⁻  in both heterozygotes ( P _I: P _Cl= 4.0 ± 0.9, n = 3) and knock-out animals ( P _I : P _Cl= 4.1 ± 1.4, n = 3). These results indicate that rat choroid plexus expresses the ClC-2 variant that was originally reported in other tissues. ClC-2 does not contribute significantly to inward-rectifying anion conductance in mouse choroid plexus, which must therefore express a novel inward-rectifying anion channel.     

Role of symptoms and lung function in determining asthma control in smokers with asthma

Background:  Cigarette smoking in asthma increases the severity and accelerates the decline in lung function. The relative role of symptoms and lung function in determining asthma control in smokers with asthma is not known.
Aim of the study:  The aim of this study was to compare asthma control in smokers vs never-smokers with asthma, using the validated Juniper asthma control questionnaire (ACQ), and assess if any difference was because of a particular symptom or the forced expiratory volume in one second (FEV₁) value.
Methods:  This was a cross-sectional study of 134 asthmatics (74 never-smokers and 60 smokers) with ≥15% reversibility in FEV₁ after salbutamol. All subjects completed the ACQ, recording FEV₁ and asthma symptoms (night awakening, morning symptoms, dyspnoea, wheeze, activity limitation and use of reliever inhaler).
Results:  Compared with the never-smokers, smokers with asthma had significantly worse median (IQR) total asthma control score [1.6 (1.1–2.3) vs 2.8 (1.7–3.4); ( P  < 0.0001)] and in each of the six individual symptom question scores ( P  < 0.001), but no difference in FEV₁ levels ( P  = 0.908).
Conclusion:  Asthma control is significantly worse in asthmatics who smoke compared with never-smokers, with all symptoms related to asthma control uniformly worse in smokers, independent of FEV₁.     

Leukotriene EM4 plasma levels in adult asthmatic patients with variable disease severity

Chavis C, van Vyve T, Chanez P, Farce M, Bousquet J, Michel FB, Godard P. Leukotriene E4 plasma levels in adult asthmatic patients with variable disease severity.
Cysteinyl leukotrienes 'C-LTs' are local inflammatory mediators involved in bronchial asthma. Seventeen asthmatic patients 'FEV₁ ranging from 41 to 99.8% of predicted values' and 11 healthy subjects were studied. The clinical severity of asthma was assessed by the Aas score. Plasma C-LTs were measured by enzyme immunoassay 'EIA' after sample purification by solid-phase extraction 'SPE', to investigate whether differences may exist between asthmatic and control subjects and whether leukotriene E₄'LTE₄' levels were related to the severity of disease. LT measurements showed that 87.6±1.2% was recovered as LTE₄ and 9.4±1.3% as LTC4. In asthmatic subjects, LTE₄ plasma levels were found to be significantly higher than those in the control group '1.073±0.133 and 0.53±0.19 ng/ml of plasma, respectively; P < 0.002'. Moreover, there was a significant correlation between LTE₄ plasma levels and the Aas clinical score ' P < 0.005'. These data suggest that plasma LTE₄ levels might be used to assess the severity of asthma.     

Interferon gamma receptor 1 gene polymorphism in patients with tuberculosis in China

The aim of the study was to examine the influence of the CA microsatellite polymorphisms of interferon gamma receptor 1 on patients with tuberculosis (TB) in the south-eastern Chinese population. Genomic DNA from patients with TB ( n  = 155) and ethnically matched controls ( n  = 89) were genotyped by short tandem repeat-PCR method. The allele frequency of (CA)₂₅ was 1.70-fold higher among patients than that among controls (95% CI 1.07–2.70) ( P  = 0.025). Compared with the non-(CA)₂₅/non-(CA)₂₅ reference group, the risk to TB of the carriers of (CA)₂₅/(CA)₂₅ genotypes were 6.46-fold (95% CI 1.40–29.74) ( P  = 0.0017) higher. On the contrary, the allele frequency of (CA)₂₆ was 0.29-fold lower in patients than that in controls (95% CI 0.11–0.76) ( P  = 0.012). Genotypes with (CA)₂₆ allele were at 0.35-fold (95% CI 0.13–0.98) ( P  = 0.045) lower to the risk of TB, compared with that of the non-(CA)₂₆/non-(CA)₂₆ in the reference group. The above results indicated that the allele (CA)₂₅ appeared to be susceptible to TB, while the allele (CA)₂₆ to be protective towards TB. Our data also suggest that the CA repeat was a highly polymorphic marker and could be used for linkage and association analysis.     

Influence of Tumour Condition on the Macrophage Activity in Candida albicans Infection

To better understand the interactions between opportunistic fungi and their hosts, we investigated hydrogen peroxide (H₂O₂)_, nitric oxide and TNF-α production by peritoneal macrophages from Ehrlich tumour-bearing mice (TBM) during microbial infections. For this purpose, TBM at days 7, 14 and 21 of tumour progression were inoculated intraperitoneally with C. albicans and evaluated after 24 and 72 h. We observed that TBM showed significant increases in H₂O_2, TNF-α levels and fungal clearance at day 7 after C. albicans infection. However, as the tumour advanced, there was a progressive decline in the release of H₂O₂ and TNF-α that was paired with the dissemination of C. albicans . These results demonstrate that protective macrophage activities against Candida albicans are limited to the initial stages of tumour growth; continued solid tumour growth weakened the macrophage response and as a consequence, weakened the host's susceptibility to opportunistic infections.     

Oxygen Partial Pressure in Outer Layers of Skin of Human Finger Nail Folds

To gain insight into oxygen transport by the cutaneous microcirculation, we have developed oxygen-sensitive microelectrodes (tip diameter ∼5 μm) to measure the distribution of P _O2 in dermal papillae of the finger nail folds of healthy human subjects. Oxygen entry into the tissue was minimised by covering the skin with a layer of paraffin oil. The finger was held under a dissecting microscope and microelectrodes were guided into position. P _O2 varied from 5–25 % of its atmospheric value, P _air (∼160 mmHg), depending on the location within the papilla. Along the axis of a papillary loop, P _O2 decreased from 40.0 ± 4.8 mmHg (mean ± s.e.m. ,   n = 6  ) at the base to 30.4 ± 5.2 mmHg (   n = 6  ) at the tip. The lowest values of P _O2, in the range of 5 % of P _air, were measured in the epidermis where the metabolism of cells was highest and the steepest P _O2 gradients were recorded in the vicinity of the epidermal–dermal boundary. When the local circulation was abruptly reduced or stopped, P _O2 fell exponentially with time, with a time constant of 8.4 ± 1.5 s (   n = 7  ). When flow was reinstated, P _O2 rose exponentially to a new value with a time constant of 4.8 ± 0.8 s (   n = 6  ). The steady state P _O2 following reperfusion was ∼23 % higher than the pre-occlusion value ( P < 0.05, ANOVA and two-tailed Student's t test) indicating localised reactive hyperaemia.     

Transgenerational endocrine pancreatic adaptation in mice from maternal protein restriction in utero

Exposure of pregnant mice to a low-protein diet (LP) impairs endocrine pancreas development in their offspring. There is evidence that this phenomenon may persist in subsequent generations. Here, we evaluated the effect of LP on glucose metabolism and pancreatic morphometry in the F3 offspring of mice at birth and weaning. LP pups in the first generation were smaller at birth, but catch-up growth; F2-LP offspring had higher body mass at birth, but there was no difference in the F3 generation. The pancreatic mass decreased in F1-LP through F3-LP at birth but increased in F2-LP at weaning. The islet volume density and diameter were smaller in all restricted groups at day 1 and 21, and F1-LP had the lowest islet number; at birth, beta cell mass was smaller in F1-LP through F3-LP and remained low throughout suckling. At day 1 and 21, pups were normoglycemic, but were hypoinsulinemic at weaning. Thus, protein restriction in mice during pregnancy produces morphologic changes in pancreatic islets, suggesting that glucose homeostasis is maintained by an increased sensitivity to insulin during the early stages of life in offspring over three consecutive generations.     

Immunohistochemical evaluation of nm23-H1 gene product in transitional cell carcinoma of the bladder

The expression of the nm23-H₁ gene has been suggested to have an inverse association with metastases in certain tumours. The aim of this study was to investigate the relationship of nm23-H₁ immunohistochemical expression with pathological tumour variables and survival in a series of transitional cell carcinomas (TCCs) of the bladder. Formalin-fixed, paraffin-embedded archival tissue from 87 carcinomas (T_a-T₁ 45 cases) and T₂-T₄ (42 cases) was immunostained (Strept ABC/ HRP) with the NDPK-A monoclonal antibody (NDPK-A) against nm23-H₁ protein. The tumours had already been evaluated for immuno-expression of p53 protein. In addition, DNA analysis was performed by flow cytometry. Results were analysed using the linear trend in proportions test, the Fisher's exact test and multivariate analysis. Paradoxically, advanced tumour stage showed significant correlation with nm23-H₁ immunopositivity in muscle invasive TCCs (P_t = 0.01). Patients with nm23-H₁ positive, muscle invasive TCCs had a worse prognosis at a level of suggestive statistical significance (P_F = 0.08). In multivariate analysis, using a Cox's proportional hazards survival model with six variables, tumour grade, disease stage and synchronous p53 and nm23-H₁ detection showed significant correlation with poor patient survival ( P  = 0.014, P  = 0.049 and P  = 0.05, respectively).     

Lymphocyte-Associated Complement: Role of C8 in Certain Cell-mediated Lytic Reactions

⁵¹Cr- labelled chicken erythrocytes (E) were treated with human     and C7 to form     , susceptible to lysis by the terminal complement components C8 and C9 ('reactive lysis') Addition of purified and extensively washed human blood lymphocytes, but not of erythrocytes, to     resulted in a similar but cell-mediated reactive lysis. Contamination of the effector cell preparations with plasma was excluded. The reaction does not require living effector cells. Its dependency on C8 was proved by inhibition with rabbit anti-human C8 as well as with its F(ab')₂ fragments. Although terminal complement components may be of importance for cell-mediated lysis of complement-carrying target cell, no effector role could be assigned to them in antibody-dependent lymphocyte mediated lysis Thus, lysis of antibody-coated chicken erythrocytes in the absence of added complement by purified human lymphocytes was not inhibited by the F(ab')₂ fragment of anti-C8.     

The effect of mitochondrial inhibitors on membrane currents in isolated neonatal rat carotid body type I cells

Inhibitors of mitochondrial energy metabolism have long been known to be potent stimulants of the carotid body, yet their mechanism of action remains obscure. We have therefore investigated the effects of rotenone, myxothiazol, antimycin A, cyanide (CN⁻) and oligomycin on isolated carotid body type I cells. All five compounds caused a rapid rise in intracellular Ca²⁺, which was inhibited on removal of extracellular Ca²⁺. Under current clamp conditions rotenone and CN⁻ caused a rapid membrane depolarization and elevation of [Ca²⁺]_i. Voltage clamping cells to −70 mV substantially attenuated this rise in [Ca²⁺]_i. Rotenone, cyanide, myxothiazol and oligomycin significantly inhibited resting background K⁺ currents. Thus rotenone, myxothiazol, cyanide and oligomycin mimic the effects of hypoxia in that they all inhibit background K⁺ current leading to membrane depolarization and voltage-gated calcium entry. Hypoxia, however, failed to have any additional effect upon membrane currents in the presence of CN⁻ or rotenone or the mitochondrial uncoupler p -trifluoromethoxyphenyl hydrazone (FCCP). Thus not only do mitochondrial inhibitors mimic the effects of hypoxia, but they also abolish oxygen sensitivity. These observations suggest that there is a close link between oxygen sensing and mitochondrial function in type I cells. Mechanisms that could account for this link and the actions of mitochondrial inhibitors are discussed.     

The effects of asphyxia on renal function in fetal sheep at midgestation

To determine whether damage to the fetal kidneys plays a role in the formation of hydrops fetalis following a severe asphyxial episode, six chronically catheterised fetal sheep, at 0.6 gestation (90 days; term 150 days), were subjected to 30 min of complete umbilical cord occlusion. During the occlusion period, mean arterial pressure, heart rate and renal blood flow decreased (   P < 0.001  ). There were falls in arterial pH and P _O2 and a rise in P _CO2 (   P < 0.001  ). Urine flow rate decreased (   P < 0.005  ), as did the excretion rates of sodium and osmoles (   P < 0.05  ). However, by 60 min after release of occlusion, urine flow rate was similar to control values. By the end of day 1, most renal variables returned to normal. At post-mortem, 72 h after occlusion, all asphyxiated fetuses showed gross signs of hydrops. Body weight was higher (   P < 0.05  ) due to fluid accumulation in the peritoneal (   P < 0.001  ) and pleural cavities (   P < 0.05  ) as well as subcutaneously (   P < 0.05  ). Amniotic/allantoic fluid volume was increased (   P < 0.05  ). Kidney histology was normal except for clusters of apoptotic cells in some proximal tubules. In conclusion, this severe asphyxial episode caused surprisingly little damage to the kidney and the changes in renal function were very transient. Thus renal damage was not important in the development of hydrops. Possibly, the midgestation fetal kidney has a limited capacity to increase urinary salt and water excretion in response to increased fluid delivery across the placenta.     

Effects of maternal hypoxia or nutrient restriction during pregnancy on endothelial function in adult male rat offspring

Compromised fetal growth impairs vascular function; however, it is unclear whether chronic hypoxia in utero affects adult endothelial function. We hypothesized that maternal hypoxia (H, 12% O₂, n = 9) or nutrient restriction (NR, 40% of control, n = 7) imposed from day 15–21 pregnancy in rats would impair endothelial function in adult male offspring (relative to control, C, n = 10). Using a wire myograph, endothelium-dependent relaxation in response to methacholine was assessed in small mesenteric arteries from 4- and 7-month-old (mo) male offspring. Nitric oxide (NO) mediation of endothelium-dependent relaxation was evaluated using N ^ω-nitro- l -arginine methyl ester ( l -NAME; NO synthase inhibitor). Observed differences in the NO pathway at 7 months were investigated using exogenous superoxide dismutase (SOD) to reduce NO scavenging, and sodium nitroprusside (SNP; NO donor) to assess smooth muscle sensitivity to NO. Sensitivity to methacholine-induced endothelium-dependent relaxation was reduced in H offspring at 4 months ( P < 0.05), but was not different among groups at 7 months. l -NAME reduced methacholine sensitivity in C ( P < 0.01), H ( P < 0.01) and NR ( P < 0.05) offspring at 4 months, but at 7 months l -NAME reduced sensitivity in C ( P < 0.05), tended to in NR ( P = 0.055) but had no effect in H offspring. SOD did not alter sensitivity to methacholine in C, but increased sensitivity in H offspring ( P < 0.01). SNP responses did not differ among groups. In summary, prenatal hypoxia, but not nutrient restriction impaired endothelium-dependent relaxation at 4 months, and reduced NO mediation of endothelial function at 7 months, in part through reduced NO bio-availability. Distinct effects following reduced maternal oxygen versus nutrition suggest that decreased oxygen supply during fetal life may specifically impact adult vascular function.     

Severe chronic urticaria is associated with elevated plasma levels of D-dimer

Background:  Patients with chronic urticaria (CU) frequently show signs of thrombin generation as a result of the activation of the extrinsic pathway of coagulation and signs of fibrinolysis as shown by slightly increased mean D-dimer plasma levels. Here, we studied patients with severe CU to see whether the activation of coagulation and fibrinolysis parallels the severity of the disease.
Methods:  Eight consecutive patients with severe exacerbations of CU and 13 with slight CU were studied. Plasma prothrombin fragment F₁₊₂ as well as D-dimer were measured by ELISA. Serum histamine-releasing activity was assessed by basophil histamine release assay. Seventy-four normal subjects were used as controls.
Results:  In patients with severe CU, median levels of both D-dimer (11.20 nmol/l) and F₁₊₂ (592 pmol/l) largely exceeded those found in patients with slight CU [D-dimer: 2.66 nmol/l ( P  = 0.001) and F₁₊₂: 228 pmol/l ( P  = 0.003)] and in normal subjects [D-dimer: 1.41 nmol/l ( P  = 0.0001) and F₁₊₂: 159 pmol/l ( P  = 0.0001)]. Sera from 25% of patients with severe CU and 31% of those with slight CU, but from none of normal subjects, showed in vitro histamine-releasing activity. D-dimer and F₁₊₂ levels were significantly correlated each other ( r  = 0.64, P  = 0.002) and with CU severity score ( r  = 0.80–0.90, P  = 0.0001), but no correlation was observed between serum histamine-releasing activity and coagulation parameters or severity score.
Conclusions:  Severe exacerbations of CU are associated with a strong activation of coagulation cascade and fibrinolysis. Whether this activation is the cause of CU or acts as an amplification system is still a matter of debate.     

Correlation among urinary eosinophil protein X, leukotriene E4, and 11-dehydrothromboxane B2 in patients with spontaneous asthmatic attack

Various kinds of cells and their mediators are thought to be involved in the pathogenesis of bronchial asthma. However, changes in each mediator or relationship among mediators during an asthmatic attack have not been well documented. In this study, to clarify whether eosinophil protein X (EPX) is a marker which is distinct from leukotriene E₄ (LTE₄), or 11-dehydrothromboxane B₂ (11DTXB₂), we measured the urinary excretion of EPX, LTE₄, and 11DTXB₂ in 14 asthmatics who were admitted to the hospital with either an acute asthmatic attack or status asthmaticus. These patients included eight atopic and six non-atopic types of bronchial asthma, with a median age of 34.0 years. Urinary excretion of EPX was significantly high on admission with the asthmatic attack, and returned to control levels 175 [122 –384] μg/day when the patients were in the improved state (1036–317 μg/day, P  < 0.01). Similar findings were observed in LTE₄ (155–59 ng/day, P  < 0.01) and 11DTXB₂ (991–442 ng/day, P  < 0.01). No significant differences in values were observed between atopic and non-atopic types of asthma in all three substances. When the individual data during the attack state were analysed, a significant correlation was observed between changes (%) in urinary EPX and those in urinary LTE₄, but no such relationship was observed between changes (%) in urinary EPX and those in urinary 11DTXB₂. These results suggest that measuring urinary EPX levels may be a useful marker for the understanding and management of the disease.     

Increased Expression of Glutathione by Estradiol, Tumor Necrosis Factor-Alpha, and Interleukin 1-Beta in Endometrial Stromal Cells

Problem  The intracellular antioxidant system, based on glutathione (GSH), plays a key role in endometrial detoxification reactions and has been proposed to be involved in the pathogenesis endometriosis. This study was designed to evaluate whether estradiol (E₂) and proinflammatory cytokines have any effects on expression of glutathione in endometrial stromal cells (ESCs).
Method of study  Glutathione levels were measured utilizing high-performance liquid chromatography following in vitro culture and treatment of ESCs with estradiol, tumor necrosis factor-alpha (TNF-α) and interleukin 1-beta (IL-1β).
Results  The GSH level in E₂ (10⁻⁸  m ) treatment group was significantly higher than in the control group at 48 h ( P  < 0.05). In vitro treatment of ESCs with TNF-α 10 ng/mL as well as E₂ (10⁻⁸  m ) plus TNF-α 10 ng/mL for 48 hr also led to a significant increase in GSH level ( P  < 0.05; P  < 0.05, respectively). Both IL-1β 10 ng/mL and E₂ (10⁻⁸  m ) plus IL-1β 10 ng/mL for 48 hr increased GSH level significantly ( P  < 0.05; P  < 0.05, respectively) as well.
Conclusions  These findings might suggest that increased production of estradiol and proinflammatory cytokines in the peritoneal cavity possibly leads to the establishment of endometriosis through increased level of GSH.     

Spontaneous, synchronous electrical activity in neonatal mouse cortical neurones

Spontaneous [Ca²⁺]_i transients were measured in the mouse neocortex from embryonic day 16 (E16) to postnatal day 6 (P6). On the day of birth (P0), cortical neurones generated widespread, highly synchronous [Ca²⁺]_i transients over large areas. On average, 52% of neurones participated in these transients, and in 20% of slices, an average of 80% participated. These transients were blocked by TTX and nifedipine, indicating that they resulted from Ca²⁺ influx during electrical activity, and occurred at a mean frequency of 0.91 min⁻¹. The occurrence of this activity was highly centred at P0: at E16 and P2 an average of only 15% and 24% of neurones, respectively, participated in synchronous transients, and they occurred at much lower frequencies at both E16 and P2 than at P0. The overall frequency of [Ca²⁺]_i transients in individual cells did not change between E16 and P2, just the degree of their synchronicity. The onset of this spontaneous, synchronous activity correlated with a large increase in Na⁺ current density that occurred just before P0, and its cessation with a large decrease in resting resistance that occurred just after P2. This widespread, synchronous activity may serve a variety of functions in the neonatal nervous system.     

The Effects of Mitogens, IL-2 and Anti-CD3 Antibody on the T-Cell Receptor Vβ Repertoire

Phytohaemagglutinin (PHA), Concanavalin A (Con A), interleukin-2 (IL-2), and monoclonal antibodies to CD3 (CD3MoAbs) are used for the assessment of the T-cell receptor (TCR) BV gene family expression in autoimmune disorders and multiple sclerosis, and to produce clones for assessment of cytokine profiles in progressive human immunodeficiency virus infection. The authors examined the effects of these stimulants on the TCR Vβ repertoire of resting and blastic CD4⁺ and CD8⁺ normal human peripheral blood lymphocytes, using three-colour cytofluorometry and a panel of anti-TCR Vβ monoclonal antibodies. IL-2 was associated with an increased percentage of blastic CD4⁺ cells expressing V_β5.1 (from median of 3.7% to 8.0%, P  = 0.0002) and blastic CD8⁺ cells expressing V_β5.3 (1.0 to 1.5%, P  = 0.0039). CD3MoAb caused a slight increase in V_β6.7 + blastic CD4⁺ cells (4.5 to 6.9%, P  = 0.0078). PHA did not alter the Vβ repertoire of blastic cells. Con A caused skewing in CD8⁺ blastic cells, toward expression of V_β5.2/5.3 (3.1 to 8.1%) and V_β5.3 (0.8 to 4.8%) ( P  = 0.0020). Thus, IL-2 stimulation causes slight alterations in the Vβ repertoire that should be taken into account in certain research settings. Con A produced skewing in CD8⁺ blastic cells suggesting that, in the presence of CD8, either Con A binds selectively to certain Vβ or the three-dimensional complex created by Con A's binding to other T-cell surface molecules induces preferential V_β5 stimulation.     

In vitro activities of new quinolones against Brucella melitensis isolated in a tertiary-care hospital in Turkey

We have evaluated the in vitro activities of seven fluoroquinolones against 69 strains of Brucella melitensis . According to their minimum inhibitory concentration for 90% growth (MIC₉₀) values, the most active agent was found to be sparfloxacin (MIC₉₀ 0.12 mg/L) followed by levofloxacin, ciprofloxacin, ofloxacin (MIC₉₀ 0.50 mg/L) and grepafloxacin (MIC₉₀ 1 mg/L), gemifloxacin (MIC₉₀ 2 mg/L) and gatifloxacin (MIC₉₀ 4 mg/L).