The effect of renal sympathetic denervation on nocturnal dipping in patients with resistant hypertension; observational data from a tertiary referral centre in the Republic of Ireland

OBJECTIVE

Renal sympathetic denervation (RSD) is an emerging device based treatment for patients with resistant hypertension. Nocturnal dipping (ND) is defined as a decrease in BP of 10-20 % during sleep, and has been shown to be protective against cardiovascular disease. This study examined the effect of RSD on the 24 h BP profile of patients with resistant hypertension.

METHODS AND RESULTS

The first 23 consecutive patients with resistant hypertension scheduled for renal denervation in a single centre were included. 24 h ambulatory blood pressure monitors (ABPM) were given to patients pre-procedure and 9 months post-procedure. RSD led to a statistically non-significant reduction in overall 24 h ABPM BP (150/85 ± 12/9 vs. 143/84 ± 15/11 mmHg; P > 0.05) despite a reduction in the number of antihypertensive medications (4.9 ± 1.2 vs. 4.3 ± 1.2; P = 0.001). There were improvements in systolic ND 1.7 ± 8 vs. 5.2 ± 8 %; P < 0.05), diastolic ND (5.2 ± 8 vs. 10.2 ± 9 %; P < 0.05) and mean arterial pressure (MAP) ND (4.2 ± 8 vs. 8.0 ± 8 %; P < 0.05). Non-significant changes in ND status were observed in systolic (17 vs. 43 % of participants; P > 0.05), diastolic (30 vs. 43 % of participants; P > 0.05) and MAP (22 vs. 39 % of participants; P > 0.05) measurements.

CONCLUSIONS

These data suggest that RSD may lead to an improvement in nocturnal dipping in selected patients with resistant hypertension. This may have cardiovascular benefits even if reduction in BP is not achieved with RSD.

Induction of bystander response in human glioma cells using high-energy electrons: a role for TGF-beta1

We examined bystander cell death produced in T98G cells by exposure to irradiated cell conditioned medium (ICCM) produced by high-energy 20 MeV electrons at a dose rate of 10 Gy min(-1) and doses up to 20 Gy. ICCM induced a bystander response in T98G glioma cells, reducing recipient cell survival by more than 25% below controls at 5 and 10 Gy. Higher doses increased survival to near control levels. ICCM was analyzed for the presence of transforming growth factor alpha (TGF-alpha) and transforming growth factor beta1 (TGF-beta1). Monoclonal antibodies for TGF-alpha (mAb TGF-alpha) and TGF-beta1 (mAb TGF-beta1) were added to the ICCM to neutralize any potential effect of the cytokines. The results indicate that TGF-alpha was not present in the ICCM and addition of mAb TGF-alpha to the ICCM had no effect on bystander cell survival. No active TGF-beta1 was present in the ICCM; however, addition of mAb TGF-beta1 completely abolished bystander death of reporter cells at all doses. These results indicate that bystander cell death can be induced in T98G glioma if a large enough radiation stress is applied and that TGF-beta1 plays a downstream role in this response.

Relative biological effectiveness of 280 keV neutrons for apoptosis in human lymphocytes

The relative biological effectiveness (RBE) of neutrons varies from unity to greater than ten depending upon neutron energy and the biological endpoint measured. In our study, we examined apoptosis in human lymphocytes to assess the RBE of low energy 280 keV neutrons compared to Cs gamma radiation and found the RBE to be approximately one. Similar results have been observed for high energy neutrons using the same endpoint. As apoptosis is a major process that influences the consequences of radiation exposure, our results indicate that biological effect and the corresponding weighting factors for 280 keV neutrons may be lower in some cell types and tissues.

TNF-related apoptosis-inducing ligand mediates human neuronal apoptosis: links to HIV-1-associated dementia

TNF-related apoptosis-inducing ligand (TRAIL) is a type II integral membrane protein that interacts with multiple receptors and cell types including neurons. In this report, TRAIL protein levels were increased in human monocyte-derived macrophages (MDM) after HIV-1 infection and immune activation. In HIV-1 encephalitic (HIVE) human brain tissue, TRAIL-expressing macrophages were found in association with active caspase-3 positive neurons. Cytotoxic TRAIL receptors 1 and 2 were expressed on neurons in primary human fetal cultures and HIV-1 encephalitic brain tissue. Furthermore, TRAIL induced a dose-dependent effect on neuronal apoptosis. These results support a role for TRAIL in mononuclear phagocyte (MP)-mediated neurotoxicity in HIV-1-associated dementia (HAD).

Up-regulation of soluble tumor necrosis factor receptor two in plasma of HIV-seropositive individuals who use opiates

Previously, we reported an increase in soluble tumor necrosis factor-alpha receptor two (sTNF-R2) and soluble CD14 (sCD14) in the plasma of HIV-seropositive individuals with neurocognitive dysfunction compared to their cognitively intact counterparts. As intravenous drug use is not only a risk factor for HIV but also an immunomodulator, we sought to examine the effects of drug use on soluble markers of immune activation. These relationships were investigated in 25 patients with late stage HIV-1 disease. TNF-alpha, sTNF-R1, sTNFR2, and sCD14 were measured in patient plasma. These values were correlated with drug use and neurocognitive function. sTNF-R2 was significantly up-regulated in those patients who used opiates compared to those who did not. There was no difference in TNF-alpha, sTNF-R1, or sCD14 between the groups. Further, there was no connection between opiate use and neurocognitive dysfunction.

Neuronal injury regulates fractalkine: relevance for HIV-1 associated dementia

Fractalkine (FKN), a chemokine highly expressed in the central nervous system, participates in inflammatory responses operative in many brain disorders including HIV-1 associated dementia (HAD). In this report, HIV-1 progeny virions and pro-inflammatory products led to FKN production associated with neuronal injury and apoptosis. FKN was produced by neurons and astrocytes; but differentially produced by the two cell types. Laboratory tests paralleled those in infected people where cerebrospinal fluid FKN levels in HIV-1 infected cognitively impaired (n=16) patients were found to be increased when compared to infected patients without cognitive impairment (n=8, P=0.0345). These results demonstrate a possible role of FKN in HAD pathogenesis.

Macrophages, chemokines and neuronal injury in HIV-1-associated dementia

Human immunodeficiency virus type-one (HIV- 1)-associated dementia (HAD) is manifested as a spectrum of behavioral, motor and cognitive dysfunctions. The disorder commonly occurs during late stage HIV disease and remains an important complication despite highly active antiretroviral therapies. A metabolic encephalopathy, fueled by neurotoxic secretions from brain mononuclear phagocytes (MP) (macrophages and microglia) underlies HIV- I neuropathogenesis. One pivotal question, however, is how brain MP evolve from neurotrophic to neurotoxic cells. The interplay between the virus, the macrophage and the neuron has just recently begun to be unraveled. Along with a multitude of other MP secretory products, chemokines effect neuronal function by engaging neuronal receptors then activating pathways that alter synaptic transmission, cell growth, injury and protection. Both neurons and glia secrete chemokines. Interestingly, HIV-1 and its gene products can mimic chemokine neuronal signaling by binding to neuronal chemokine receptors or by other non-specific mechanisms. The elucidation of mechanisms involved in chemokine-mediated neural compromise will likely provide unique insights into the pathogenesis and treatment, not only of HAD, but of a wide range of neurodegenerative disorders.

Plasma levels of soluble CD14 and tumor necrosis factor-alpha type II receptor correlate with cognitive dysfunction during human immunodeficiency virus type 1 infection

The relationship between monocyte immune responses and cognitive impairment during progressive human immunodeficiency virus type 1 (HIV-1) infection was investigated in 28 subjects receiving highly active antiretroviral therapy. The mean+/-SEM CD4(+) T lymphocyte count and virus load for all patients were 237+/-41 cells/mm(3) and 77,091+/-195,372 HIV-1 RNA copies/mL, respectively. Levels of soluble tumor necrosis factor-alpha type II receptor (sTNF-RII) and soluble CD14 (sCD14) were measured in plasma by ELISA and were correlated with results from neuropsychological, magnetic resonance imaging, and magnetic resonance spectroscopy tests. Plasma sCD14 and sTNF-RII levels were elevated in subjects with cognitive impairment and in those with brain atrophy. Furthermore, both factors were correlated with spectroscopic choline:creatine ratios. These findings support the idea that peripheral immune responses are linked to cognitive dysfunction during advanced HIV-1 disease.

Cotton dust and endotoxin exposure and long-term decline in lung function: results of a longitudinal study

BACKGROUND

To evaluate the relationship between long-term exposure to cotton dust and Gram-negative bacterial endotoxin on lung function, we conducted an 11-year follow-up study of cotton textile workers in Shanghai, China.

METHODS

Workers at a nearby silk-thread manufacturing mill were used as a referent population. Ninety percent of the original cohort of 445 cotton and 467 silk textile workers--both active and retired--were identified for testing in the 11th year. Questionnaires and spirometric testing were performed, as well as cotton dust and endotoxin sampling at three points over the 11-year follow-up period: at baseline, at Year 5, and at Year 11. After excluding deaths and subjects on sick-leave, 84% of the original cohort had complete health and environmental data.

RESULTS

The data were reanalyzed using generalized estimating equations feedback model which allow for subject transfer over time between work areas, various exposure levels to dust and endotoxin, and FEV1. Cotton workers had a larger loss of FEV1 during the first 5 years of study (-40 mls/yr) as compared with the second 6 years of follow-up (-18 mls/yr). During the same periods, the average decline among silk workers was slightly higher in the first period, but was more consistent (-30 mls/yr vs. -27 mls/yr), and these differences could not be explained by worker selection or dropout. When cumulative exposure to dust and endotoxin were estimated and used in a multivariate model (GEE) for FEV1 loss, cumulative dust, but not endotoxin, was associated with 11-year loss in FEV1 after adjustments for confounders. There was evidence of feedback between dust-exposure levels and FEV1, indicating the existence of a healthy-worker survivor effect. After accounting for a healthy-worker survivor effect, we found a significant relationship between dust exposure and FEV1 decline.

CONCLUSIONS

Our results suggest that cotton dust is more strongly associated with chronic airflow limitation than associated endotoxins. Further work is needed to clarify potential reversibility after cessation of exposure, and the relative contributions of dust, endotoxin, and tobacco to chronic respiratory impairment in cotton and other vegetable-exposed workers.

Order effects and the weighting process in workload assessment

Operators controlling a power grid were subjects in a mental workload experiment in which they performed their normal tasks under simulated quiet and busy conditions. Workload was assessed using the NASA Task-Load Index (TLX). It was found that there were significant differences between the two conditions, but there were no order effects. The value of the weighting procedure was assessed by correlating unweighted and weighted workload ratings. Although the correlations were high, they were not perfect, indicating some value for weighting the dimensions of the TLX. Large individual differences were observed in perceived workload.