Vagus nerve stimulation parameters evoke differential neuronal responses in the locus coeruleus

Vagus nerve stimulation (VNS) is used to treat drug-resistant epilepsy and depression, with additional applications under investigation. The noradrenergic center locus coeruleus (LC) is vital for VNS effects; however, the impact of varying stimulation parameters on LC activation is poorly understood. This study characterized LC activation across VNS parameters. Extracellular activity was recorded in rats' left LC while 11 VNS paradigms, utilizing variable frequencies and bursting characteristics, were pseudorandomly delivered to the left cervical vagus for five cycles. Neurons' change from baseline firing rate and timing response profiles were assessed. The proportion of neurons categorized as responders over 5 VNS cycles doubled in comparison to the first VNS cycle (p < 0.001) for all VNS paradigms, demonstrating an amplification effect. The percentage of positively consistent/positive responders increased for standard VNS paradigms with frequencies ≥10 Hz and for bursting paradigms with shorter interburst intervals and more pulses per burst. The synchrony between pairs of LC neurons increased during bursting VNS but not standard paradigms. Also, the probability of evoking a direct response during bursting VNS was higher with longer interburst intervals and a higher number of pulses per burst. Standard paradigms between 10-30 Hz best positively activates LC with consistency to VNS while the best bursting paradigm to increase activity was 300 Hz, seven pulses per burst separated by 1 s. Bursting VNS was effective in increasing synchrony between pairs of neurons, suggesting a common network recruitment originating from vagal afferents. These results indicate differential activation of LC neurons depending on the VNS parameters delivered.

Comparative Enhancement of Motor Function and BDNF Expression Following Different Brain Stimulation Approaches in an Animal Model of Ischemic Stroke

BACKGROUND

Combinatory intervention such as high-frequency (50-100 Hz) excitatory cortical stimulation (ECS) given concurrently with motor rehabilitative training (RT) improves forelimb function, except in severely impaired animals after stroke. Clinical studies suggest that low-frequency (≤1 Hz) inhibitory cortical stimulation (ICS) may provide an alternative approach to enhance recovery. Currently, the molecular mediators of CS-induced behavioral effects are unknown. Brain-derived neurotrophic factor (BDNF) has been associated with improved recovery and neural remodeling after stroke and thus may be involved in CS-induced behavioral recovery.

OBJECTIVE

To investigate whether inhibitory stimulation during RT improves functional recovery of severely impaired rats, following focal cortical ischemia and if this recovery alters BDNF expression (study 1) and depends on BDNF binding to TrkB receptors (study 2).

METHODS

Rats underwent ECS + RT, ICS + RT, or noCS + RT treatment daily for 3 weeks following a unilateral ischemic lesion to the motor cortex. Electrode placement for stimulation was either placed ipsilateral (ECS) or contralateral (ICS) to the lesion. After treatment, BDNF expression was measured in cortical tissue samples (study 1). In study 2, the TrkB inhibitor, ANA-12, was injected prior to treatment daily for 21 days.

RESULTS

ICS + RT treatment significantly improved impaired forelimb recovery compared with ECS + RT and noCS + RT treatment.

CONCLUSION

ICS given concurrently with rehabilitation improves motor recovery in severely impaired animals, and alters cortical BDNF expression; nevertheless, ICS-mediated improvements are not dependent on BDNF binding to TrkB. Conversely, inhibition of TrkB receptors does disrupt motor recovery in ECS + RT treated animals.

Serum hyaluronic acid in patients with veno-occlusive disease following bone marrow transplantation

The development of hepatic veno-occlusive disease following bone marrow transplantation is associated with high-dose combination cytoreductive therapy. Experimental models have suggested that drug-induced injury to hepatic sinusoidal endothelial cells is involved in the pathogenesis of this syndrome. Hyaluronic acid is a polysaccharide that is metabolized, almost exclusively, by hepatic sinusoidal endothelial cells. The aim of the present study was to evaluate serum hyaluronic acid as a marker for endothelial cell injury in patients with veno-occlusive disease following bone marrow transplantation. Hyaluronic acid was measured in sera from patients with and without veno-occlusive disease using an enzyme-linked protein binding assay. Mean peak serum hyaluronic acid levels were significantly greater in patients who had a diagnosis of VOD compared to those transplant patients who did not, 1173.4 +/- 982.9 vs 444.9 +/- 735.6 ng/ml (P = 0.01). Serial serum samples obtained from a separate cohort of patients also demonstrated that serum hyaluronic acid levels were higher in patients with moderate or severe veno-occlusive disease compared to those with none or mild disease at days 7, 17 and 25 following transplantation (greatest difference at day 25: 366 +/- 327 vs 126 +/- 151, P = 0.01). Serum hyaluronic acid levels are increased in veno-occlusive disease and increase over time in patients with severe disease. Further studies are required to determine if elevated serum hyaluronic acid levels are due to decreased clearance by injured hepatic sinusoidal endothelial cells or increased production from early hepatic fibrogenesis associated with the acute liver injury.

Tumor necrosis factor-alpha soluble receptor p55 (sTNFp55) and risk of preeclampsia in Peruvian women

We conducted a large case-control study to assess the risk of preeclampsia with elevated sTNFp55 concentrations (markers of excessive TNF-alpha release) in Peruvian women. A total of 125 women with preeclampsia and 179 normotensive women were included in a study conducted during the period, June 1997 through January 1998. Antepartum (third-trimester) plasma sTNFp55 was measured by enzyme linked immunosorbent assay. Mean plasma sTNFp55 concentrations were 32.4% higher among preeclampsia cases (920.1+/-30.4 pg/ml) as compared with controls (694.8+/-15.0 pg/ml, Student's t-test P<0.001). There was a strong linear increase in risk of preeclampsia with increasing concentrations of sTNFp55 (linear trend P-value <0. 001). After adjusting for confounding factors, women in the highest quartile experienced a 10-fold increased risk of preeclampsia as compared with women in the lowest quartile (adjusted odds ratio, 10.3; 95% confidence interval, 4.1-25.9). Compared with women in the highest quartile, women in the second and third quartiles experienced a 3-fold or greater increased risk of preeclampsia (adjusted odds ratios were 3.1 and 3.8, respectively). Excessive TNF-alpha release (as measured by the detection of the soluble receptor sTNFp55 in maternal plasma collected before delivery) is increased in pregnancies complicated by preeclampsia as compared with normotensive pregnancies. These findings are consistent with most previous studies.

Maternal second trimester serum tumor necrosis factor-alpha-soluble receptor p55 (sTNFp55) and subsequent risk of preeclampsia

Preeclampsia is characterized by diffuse vascular endothelial dysfunction. Tumor necrosis factor-alpha (TNF-alpha), which plays a key role in the cytokine network responsible for immunoregulation, is also known to contribute to endothelial dysfunction and other metabolic disturbances noted in preeclampsia. Results from cross-sectional studies and one longitudinal study indicate that TNF-alpha (or its soluble receptor, sTNFp55) is increased in the peripheral circulation and amniotic fluid of women with preeclampsia as compared with normotensive women. Between December 1993 and August 1994, prediagnostic sTNFp55 concentrations (a marker of excessive TNF-alpha release) were measured in 35 women with preeclampsia and 222 normotensive women to determine whether elevations precede the clinical manifestation of the disorder. Logistic regression procedures were used to calculate maximum likelihood estimates of odds ratios and 95% confidence intervals. Mean second trimester (15-22 weeks' gestation) serum sTNFp55 concentrations, measured by enzyme-linked immunosorbent assay, were 14.4% higher in preeclamptic women than in normotensive controls (716.6 pg/ml (standard deviation 193.6) vs. 626.4 pg/ml (standard deviation 158.0); p = 0.003). The relative risk of preeclampsia increased across successively higher quintiles of sTNFp55 (odds ratios were 1.0, 1.3, 2.1, and 3.7, with the lowest quintile used as the referent; p for trend = 0.007). After adjustment for maternal age, adiposity, and parity, the relative risk between extreme quintiles was 3.3 (95% confidence interval 0.8-13.4). These findings indicate that the level of TNF-alpha in maternal circulation is increased prior to the clinical manifestation of the disorder, and they are consistent with the hypothesized role of cytokines in mediating endothelial dysfunction and the pathogenesis of preeclampsia. Further work is needed to identify modifiable risk factors for the excessive synthesis and release of TNF-alpha in pregnancy, and to assess whether lowering of TNF-alpha concentrations in pregnancy alters the incidence and severity of preeclampsia.

Plasma tumor necrosis factor-alpha soluble receptor p55 (sTNFp55) concentrations in eclamptic, preeclamptic and normotensive pregnant Zimbabwean women

We sought to examine the relationship between excessive tumor necrosis factor-alpha (TNF-alpha) release (as measured by sTNFp55 plasma concentrations) and risk of eclampsia and preeclampsia, respectively, among sub-Saharan African women delivering at Harare Maternity Hospital, Zimbabwe. In total, 33 pregnant women with eclampsia, 138 women with preeclampsia and 185 normotensive women were included in a case-control study conducted during the period, June 1995 through April 1996. Postpartum plasma sTNFp55 was measured by enzyme linked immunosorbent assay. Women with eclampsia had significantly higher sTNFp55 than normotensive controls (1.87 vs 1.35 ng/ml, P<0.001). Similarly, women with preeclampsia had sTNFp55 concentrations higher than normotensive controls (1.69 vs 1.35 ng/ml, P < 0.001). The odds ratio for eclampsia was 5.00 (adjusted odds ratio (OR) 5.00, 95% confidence interval (CI) 1.20-20.92) among women in the highest quartile of the control sTNFp55 distribution compared with women in the lowest quartile. The corresponding odds ratio and 95% CI for preeclampsia was 2.37 (1.11-5.06). Postpartum plasma sTNFp55 concentrations are increased among Zimbabwean women with eclampsia and preeclampsia as compared with their normotensive counterparts. These findings are consistent with the hypothesized role of cytokines in mediating endothelial dysfunction and the pathogenesis of preeclampsia/eclampsia. Additional work is needed to identify modifiable risk factors for the excessive synthesis and release of TNF-alpha in pregnancy; and to assess whether measurements of sTNFp55 early in pregnancy may be used to identify women likely to benefit from anti-inflammatory therapy.

Plasma thrombopoietin levels in marrow transplant patients with veno-occlusive disease of the liver

Platelet transfusion requirements are higher among patients with veno-occlusive disease (VOD), compared to patients without VOD. One possible explanation is inadequate production of thrombopoietin (TPO), a protein synthesized in the liver. We prospectively studied 28 patients to test the hypothesis that plasma TPO levels were decreased in patients who developed VOD. Plasma TPO levels to day +30 were measured by ELISA (normal, 0.36+/-0.15 fmol/ml). VOD developed in 18/28 patients. Platelet transfusion requirements were significantly different in patients with and without VOD (97+/-46.1 units vs 51+/-33.2 units, P = 0.008). Plasma TPO levels were elevated at baseline (10.8+/-13.0 fmol/ml) and increased after transplant, with peak values of 32.3+/-10.3 fmol/ml at day +7. TPO levels were significantly higher at days +7 and +17 among patients with VOD than among those without VOD (P < 0.01). Regression analysis of TPO levels vs platelet counts showed a significant inverse relationship. We conclude that TPO levels were higher in patients with VOD and were inversely correlated with platelet counts, suggesting that regulation of TPO levels was related to platelet mass. Thrombocytopenia in patients with VOD cannot be explained by inadequate hepatic synthesis of TPO.

A role for tumour necrosis factor-alpha, Fas and Fas-Ligand in marrow failure associated with myelodysplastic syndrome

Apoptosis of haemopoietic cells in the marrow of patients with myelodysplastic syndrome (MDS) has been suggested as a mechanism for peripheral cytopenias. We determined the expression of Fas (CD95), Fas-Ligand (Fas-L) and TNF-alpha factors known to be involved in apoptosis, in the marrow of 44 patients with MDS and characterized their functional relevance in in vitro assays of haemopoiesis. Multidimensional flow cytometry revealed phenotypically aberrant blasts as defined by orthogonal light scatter and CD45 expression in the marrow of 24/44 patients. Among those blasts Fas expression was increased on CD34-positive cells and on cells co-expressing HLA-DR. In addition, Fas-L was expressed on some CD34+ cells of MDS patients but was never detected on CD34+ cells in normal marrow. Fas and Fas-L mRNAs as well as mRNA for TNF-alpha, known to increase Fas expression in normal marrow, were up-regulated in patients with MDS. TNF-alpha protein and sTNF-R1 levels in marrow plasma were higher in MDS patients than in controls (P<0.002 and <0.003, respectively). However, results were dependent upon disease category: TNF-alpha levels were significantly higher in patients with refractory anaemia (RA) than in patients with RA with excess blasts (RAEB) or RAEB in transformation (RAEB-T) (P=0.043). Conversely, the proportion of Fas-L-positive cells was lowest in patients with RA (P=0.037). In marrow cultures, Fas-Ig, rhuTNFR:Fc or anti-TNF-alpha antibody, by blocking Fas or TNF mediated signals, respectively, significantly increased the numbers of haemopoietic colonies compared to untreated cells (P<0.001, P<0.003, P<0.001, respectively). These results show significant dysregulation in the expression of TNF-alpha, Fas and Fas-L in the marrow from MDS patients. Altered expression of these molecules appears to be of functional relevance in the dysregulation of haemopoiesis in MDS and may be amenable to therapeutic interventions.

Oral beclomethasone dipropionate for treatment of intestinal graft-versus-host disease: a randomized, controlled trial

BACKGROUND & AIMS

Beclomethasone dipropionate (BDP), a topically active steroid, seemed to be an effective treatment for intestinal graft-versus-host disease (GVHD) in a phase I study. The aim of this study was to compare the effectiveness of oral BDP to that of placebo capsules in treatment of intestinal GVHD.

METHODS

Sixty patients with anorexia and poor oral intake because of intestinal GVHD were randomized to receive prednisone (1 mg.kg-1.day-1) plus either oral BDP (8 mg/day) or placebo capsules. Initial responders who were eating at least 70% of caloric needs at evaluation on day 10 continued to take study capsules for an additional 20 days while the prednisone dose was rapidly tapered. The primary end point was the frequency of a durable treatment response at day 30 of treatment.

RESULTS

The initial treatment response at day 10 was 22 of 31 (71%) in the BDP/prednisone group vs. 16 of 29 (55%) for the placebo/prednisone group. The durable treatment response at day 30 was 22 of 31 (71%) vs. 12 of 29 (41%), respectively (P = 0.02).

CONCLUSIONS

The combination of oral BDP capsules and prednisone was more effective than prednisone alone in treating intestinal GVHD. Oral BDP allowed prednisone doses to be rapidly tapered without recurrent intestinal symptoms.

Crystal structure of the ferromagnetic polymer potassium Bis(carbonato)cuprate(II)

The crystal structure of the title compound, K2Cu(CO3)2, has been determined by single-crystal X-ray diffraction at 295(1) K, and refined by least squares to a residual of 0.027 for 1441 'observed' reflections. Crystals are orthorhombic, space group Fdd2, a 11.425(3), b 17.658(4), c 6.154(2) A, Z 8. The structure comprises potassium cations embedded in an infinite three-dimensional polymeric anionic array of square-planar coordinated copper atoms with bridging carbonate groups [Cu-O 1.934(2), 1.936(2) Ǻ]. Within the latter, the non- coordinating oxygen-carbon bond is shorter [1.259(3) Ǻ] than the other two [1.303(3), 1.307(2) Ǻ] and the O-C-O angle opposite it is correspondingly reduced to 117.1(2)°. The CO3 plane lies at 83.9° to the CuO4 'plane'.