Nitrite infusion in humans and nonhuman primates: endocrine effects, pharmacokinetics, and tolerance formation

BACKGROUND

The recent discovery that nitrite is an intrinsic vasodilator and signaling molecule at near-physiological concentrations has raised the possibility that nitrite contributes to hypoxic vasodilation and to the bioactivity of nitroglycerin and mediates the cardiovascular protective effects of nitrate in the Mediterranean diet. However, important questions of potency, kinetics, mechanism of action, and possible induction of tolerance remain unanswered.

METHODS AND RESULTS

In the present study, we performed biochemical, physiological, and pharmacological studies using nitrite infusion protocols in 20 normal human volunteers and in nonhuman primates to answer these questions, and we specifically tested 3 proposed mechanisms of bioactivation: reduction to nitric oxide by xanthine oxidoreductase, nonenzymatic disproportionation, and reduction by deoxyhemoglobin. We found that (1) nitrite is a relatively potent and fast vasodilator at near-physiological concentrations; (2) nitrite functions as an endocrine reservoir of nitric oxide, producing remote vasodilation during first-pass perfusion of the opposite limb; (3) nitrite is reduced to nitric oxide by intravascular reactions with hemoglobin and with intravascular reductants (ie, ascorbate); (4) inhibition of xanthine oxidoreductase with oxypurinol does not inhibit nitrite-dependent vasodilation but potentiates it; and (5) nitrite does not induce tolerance as observed with the organic nitrates.

CONCLUSIONS

We propose that nitrite functions as a physiological regulator of vascular function and endocrine nitric oxide homeostasis and suggest that it is an active metabolite of the organic nitrates that can be used therapeutically to bypass enzymatic tolerance.

Erythrocytes are the major intravascular storage sites of nitrite in human blood

Plasma levels of nitrite ions have been used as an index of nitric oxide synthase (NOS) activity in vivo. Recent data suggest that nitrite is a potential intravascular repository for nitric oxide (NO), bioactivated by a nitrite reductase activity of deoxyhemoglobin. The precise levels and compartmentalization of nitrite within blood and erythrocytes have not been determined. Nitrite levels in whole blood and erythrocytes were determined using reductive chemiluminescence in conjunction with a ferricyanide-based hemoglobin oxidation assay to prevent nitrite destruction. This method yields sensitive and linear measurements of whole blood nitrite over 24 hours at room temperature. Nitrite levels measured in plasma, erythrocytes, and whole blood from 15 healthy volunteers were 121 plus or minus 9, 288 plus or minus 47, and 176 plus or minus 17 nM, indicating a surprisingly high concentration of nitrite within erythrocytes. The majority of nitrite in erythrocytes is located in the cytosol unbound to proteins. In humans, we found a significant artery-to-vein gradient of nitrite in whole blood and erythrocytes. Shear stress and acetylcholine-mediated stimulation of endothelial NOS significantly increased venous nitrite levels. These studies suggest a dynamic intravascular NO metabolism in which endothelial NOS-derived NO is stabilized as nitrite, transported by erythrocytes, and consumed during arterial-to-venous transit.

Inhaled nebulized nitrite is a hypoxia-sensitive NO-dependent selective pulmonary vasodilator

The blood anion nitrite contributes to hypoxic vasodilation through a heme-based, nitric oxide (NO)-generating reaction with deoxyhemoglobin and potentially other heme proteins. We hypothesized that this biochemical reaction could be harnessed for the treatment of neonatal pulmonary hypertension, an NO-deficient state characterized by pulmonary vasoconstriction, right-to-left shunt pathophysiology and systemic hypoxemia. To test this, we delivered inhaled sodium nitrite by aerosol to newborn lambs with hypoxic and normoxic pulmonary hypertension. Inhaled nitrite elicited a rapid and sustained reduction ( approximately 65%) in hypoxia-induced pulmonary hypertension, with a magnitude approaching that of the effects of 20 p.p.m. NO gas inhalation. This reduction was associated with the immediate appearance of NO in expiratory gas. Pulmonary vasodilation elicited by aerosolized nitrite was deoxyhemoglobin- and pH-dependent and was associated with increased blood levels of iron-nitrosyl-hemoglobin. Notably, from a therapeutic standpoint, short-term delivery of nitrite dissolved in saline through nebulization produced selective, sustained pulmonary vasodilation with no clinically significant increase in blood methemoglobin levels. These data support the concept that nitrite is a vasodilator acting through conversion to NO, a process coupled to hemoglobin deoxygenation and protonation, and evince a new, simple and inexpensive potential therapy for neonatal pulmonary hypertension.

Transplant glomerulopathy, late antibody-mediated rejection and the ABCD tetrad in kidney allograft biopsies for cause

To define the relative frequency of phenotypes of transplant glomerulopathy, we retrospectively reviewed the findings in 1036 biopsies for clinical indications from 1320 renal transplant patients followed in our clinics between 1997 and 2005. Transplant glomerulopathy, defined by double contours of glomerular basement membranes (D), was diagnosed in 53 biopsies (5.1%) from 41 patients (3.1%) at a median of 5.5 years post-transplant (range 3.8-381 months). In cases with D, we studied the frequency of circulating anti-HLA alloantibody (A), peritubular capillary basement membrane multilayering (B) and peritubular capillary C4d deposition (C). B was present in 48 (91%) of D biopsies. C4d staining by indirect immunofluorescence was detected in 18 of 50 D biopsies studied (36%). By Flow PRA Screening or ELISA, A was detected in 33 (70%) in 47 D cases with available sera, of which 28/33 or 85% were donor-specific. Class II (13/33) or class I and II (17/33) were more common than class I (3/33) antibodies. Thus 73% of transplant glomerulopathy has evidence of alloantibody-mediated injury (A and/or C), with ABCD and ABD being the common phenotypes in biopsies for cause. The remaining 27%, mostly BD, may be a different disease or a stage in which A and C are undetectable.

The Notochordal Cell in the Nucleus Pulposus: A Review in the Context of Tissue Engineering

An understanding of developmental biology can provide useful insights into how different tissue-engineered repairs might be designed. During embryogenesis of the intervertebral disk, the cells of the notochord play a critical role in initiating tissue formation, and may be responsible for development of the nucleus pulposus. In some species, including humans, these notochordal cells may eventually be lost, either through apoptosis or terminal differentiation, and are replaced by chondrocyte-like cells. However, there is some evidence that the notochordal cells may persist in at least some humans. This review discusses some of the potential applications of notochordal cells in tissue engineering of the nucleus pulposus.

Hemodynamic and functional assessment of patients with sickle cell disease and pulmonary hypertension

RATIONALE

Although pulmonary hypertension (PH) is a common complication of sickle cell disease (SCD) associated with high mortality, there exist few data characterizing hemodynamics and cardiopulmonary function in this population.

OBJECTIVES

To characterize hemodynamics and cardiopulmonary function in patients with SCD with and without PH.

METHODS

Patients with SCD with PH (n = 26) were compared with control subjects with SCD but without PH (n = 17), matched for age, hemoglobin levels, and fetal hemoglobin levels.

MEASUREMENTS AND MAIN RESULTS

Upon catheterization, 54% of the patients with PH had pulmonary arterial hypertension, and 46% had pulmonary venous hypertension. When compared with control subjects, patients with PH exhibited lower six-minute-walk distance (435 +/- 31 vs. 320 +/- 20 m, p = 0.002) and oxygen consumption (50 +/- 3% vs. 41 +/- 2% of predicted, p = 0.02), and also had mild restrictive lung disease and more perfusion abnormalities on radionuclide lung scans. The six-minute-walk distance in this population inversely correlated with tricuspid regurgitant jet velocity (r = -0.55, p < 0.001), and mean pulmonary artery pressure (r = -0.57, p < 0.001), and directly correlated with maximal oxygen consumption (r = 0.49, p = 0.004), even after adjustment for hemoglobin, supporting an independent contribution of increasing pulmonary artery pressures to loss of exercise capacity.

CONCLUSIONS

Patients with SCD-associated PH have both pulmonary arterial and venous PH associated with severe limitations in exercise capacity, likely compounded by interstitial lung fibrosis and severe anemia. These data support the use of the six-minute-walk distance as an index of PH and cardiopulmonary function in patients with SCD.

Sildenafil therapy in patients with sickle cell disease and pulmonary hypertension

Pulmonary hypertension is a frequent complication of sickle cell disease that is associated with haemolysis, impaired nitric oxide bioavailability and high mortality. We sought to evaluate the safety and efficacy of selective pulmonary vasodilators and antiproliferative agents in this at-risk population. After optimising sickle cell disease therapy to stabilise haemoglobin and fetal haemoglobin levels, we evaluated the safety and efficacy of sildenafil in 12 patients with sickle cell disease and pulmonary hypertension. Sildenafil therapy (mean duration 6 +/- 1 months) decreased the estimated pulmonary artery systolic pressure [50 +/- 4 to 41 +/- 3 mmHg; difference 9 mmHg, 95% confidence interval (CI): 0.3-17, P = 0.043] and increased the 6-min walk distance (384 +/- 30 to 462 +/- 28 m; difference 78 m, 95% CI: 40-117, P = 0.0012). Transient headaches occurred in two patients and transient eye-lid oedema in four patients. No episodes of priapism occurred in the three men in the study; two of them were on chronic exchange transfusions and one had erectile dysfunction.

IN CONCLUSION

(1) sickle cell disease patients with anaemia and pulmonary hypertension have significant exercise limitation; (2) the 6-min walk distance may be a valid endpoint in this population; (3) therapy with sildenafil appears safe and improves pulmonary hypertension and exercise capacity. Additional phase I studies in males with sickle cell disease followed by phase II/III placebo controlled trials evaluating the safety and efficacy of sildenafil therapy in sickle cell disease patients with pulmonary hypertension are warranted.

The measurement of blood and plasma nitrite by chemiluminescence: pitfalls and solutions

There are a number of difficulties involved in the quantification of nitrite in biological systems. These difficulties result from oxidation of nitrite (within minutes) by heme proteins, such as hemoglobin, myoglobin, cytoglobin, and neuroglobin; its low levels in vivo; and its ubiquitous presence in laboratory buffers and glassware. The goal of this review is to present an assay suitable for the sensitive and specific measurement of intravascular nitrite in mammals using the chemiluminescence-based nitric oxide analyzer and to inform the reader on how to evade the pitfalls pertinent to nitrite determination in biological matrices.

Emerging role of nitrite in human biology

Nitric oxide (NO) plays a fundamental role in maintaining normal vascular function. NO is produced by endothelial cells and diffuses both into smooth muscle causing vasodilation and into the vessel lumen where the majority of this highly potent gas is rapidly inactivated by dioxygenation reaction with oxyhemoglobin to form nitrate. Diffusional barriers for NO around the erythrocyte and along the endothelium in laminar flowing blood reduce the inactivation reaction of NO by hemoglobin, allowing sufficient NO to escape for vasodilation and also to react in plasma and tissues to form nitrite anions (NO(2)(-)) and NO-modified peptides and proteins (RX-NO). Several recent studies have highlighted the importance of the nitrite anion in human biology. These studies have shown that measurement of plasma nitrite is a sensitive index of constitutive NO synthesis, suggesting that it may be useful as a marker of endothelial function. Additionally, recent evidence suggests that nitrite represents a circulating storage pool of NO and may selectively donate NO to hypoxic vascular beds. The conversion of nitrite to NO requires a reaction with a deoxygenated heme protein, suggesting a novel function of hemoglobin as a deoxygenation-dependent nitrite reductase. This review focuses on the role of nitrite as a circulating NO donor, its potential as an index of NO synthase (NOS) activity and endothelial function, and discusses potential diagnostic and therapeutic applications.

Expression of Drosophila lamin C is developmentally regulated: analogies with vertebrate A-type lamins

Vertebrate nuclear lamins form a multigene family with developmentally controlled expression. In contrast, invertebrates have long been thought to contain only a single lamin, which in Drosophila is the well-characterized lamin Dm0. Recently, however, a Drosophila cDNA clone (pG-IF) has been identified that codes for an intermediate filament protein which harbors a nuclear localization signal but lacks a carboxy-terminal CAAX motif. Based on these data the putative protein encoded by pG-IF was tentatively called Drosophila lamin C. To address whether the pG-IF encoded protein is expressed and whether it encodes a cytoplasmic intermediate filament protein or a nuclear lamin we raised antibodies against the recombinant pG-IF protein. The antibodies decorate the nuclear envelope in Drosophila Kc tissue culture cells as well as in salivary and accessory glands demonstrating that pG-IF encodes a nuclear lamin (lamin C). Antibody decoration, in situ hybridization, western and northern blotting studies show that lamin C is acquired late in embryogenesis. In contrast, lamin Dm0 is constitutively expressed. Lamin C is first detected in late stage 12 embryos in oenocytes, hindgut and posterior spiracles and subsequently also in other differentiated tissues. In third instar larvae lamins C and Dm0 are coexpressed in all tissues tested. Thus, Drosophila has two lamins: lamin Dm0, containing a CaaX motif, is expressed throughout, while lamin C, lacking a CaaX motif, is expressed only later in development. Expression of Drosophila lamin C is similar to that of vertebrate lamin A (plus C), which loses its CaaX motif during incorporation into the lamina.

IL-12 suppression during experimental endotoxin tolerance: dendritic cell loss and macrophage hyporesponsiveness

Endotoxin tolerance, the transient, secondary down-regulation of a subset of endotoxin-driven responses after exposure to bacterial products, is thought to be an adaptive response providing protection from pathological hyperactivation of the innate immune system during bacterial infection. However, although protecting from the development of sepsis, endotoxin tolerance also can lead to fatal blunting of immunological responses to subsequent infections in survivors of septic shock. Despite considerable experimental effort aimed at characterizing the molecular mechanisms responsible for a variety of endotoxin tolerance-related phenomena, no consensus has been achieved yet. IL-12 is a macrophage- and dendritic cell (DC)-derived cytokine that plays a key role in pathological responses to endotoxin as well as in the induction of protective responses to pathogens. It recently has been shown that IL-12 production is suppressed in endotoxin tolerance, providing a likely partial mechanism for the increased risk of secondary infections in sepsis survivors. We examined the development of IL-12 suppression during endotoxin tolerance in mice. Decreased IL-12 production in vivo is clearly multifactorial, involving both loss of CD11c(high) DCs as well as alterations in the responsiveness of macrophages and remaining splenic DCs. We find no demonstrable mechanistic role for B or T lymphocytes, the soluble mediators IL-10, TNF-alpha, IFN-alphabeta, or nitric oxide, or the NF-kappaB family members p50, p52, or RelB.

Gabapentin for essential tremor: a multiple-dose, double-blind, placebo-controlled trial

Essential tremor (ET) is a common movement disorder that often becomes refractory to conventional pharmacologic management. Open-label studies suggest that gabapentin is efficacious for ET, but the results of controlled trials have been mixed. To determine the efficacy and tolerability of gabapentin in ET, we conducted a double-blind, placebo-controlled, cross-over trial evaluating two doses (1800 mg per day and 3600 mg per day; N = 25). Patients on other ET medications were maintained on their concurrent medications for 3 months prior to study initiation and throughout the study. Twenty patients (mean age, 69.9 +/- 6.1 yrs) completed the study. Overall, patient global assessments (p <0.05), observed tremor scores (p <0.005), water pouring scores (p <0.05), and activities of daily living scores (p <0.005) significantly improved. Accelerometry scores, spirographs, and investigator global impression scores did not improve. The results were similar for high and low doses. Statistical regression models did not demonstrate any significant predictors for response. Gabapentin may be effective in some cases of ET.

Association of homozygous 7048G7049 variant in the intron six of Nurr1 gene with Parkinson's disease

OBJECTIVE

To determine whether the Nurr1 gene, which is critical for the development and maintenance of nigral dopaminergic neurons, is a risk factor associated with PD.

BACKGROUND

The Nurrl gene is highly expressed in the dopaminergic neurons in the midbrain. Knockout of the gene results in agenesis of nigral dopaminergic neurons and heterozygous knockout mice increases 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced neurotoxicity.

METHODS

This study included 105 patients with familial PD (fPD) and 120 patients with sporadic PD (sPD) and 221 age-matched healthy control subjects. The polymorphisms and mutations of the Nurr1 gene in patients with PD were initially examined by heteroduplex analysis and sequencing analysis from PCR-amplified Nurr1 gene fragments. A polymorphism in the BseRI restriction site was identified, and a relatively large-scale analysis then was conducted by three independent investigators who were blinded to the clinical status of the subjects.

RESULTS

A homozygous 7048G7049 polymorphism was found in intron 6 of the Nurr1 gene, which was significantly higher in fPD (10/105; 9.5%) and in sPD (5/120; 4.2%) compared with healthy control subjects (2/221; 0.9%). The mean age and the SD at onset of these homozygote patients with PD was 52 +/- 15 years for fPD and 46 +/- 7 years for sPD. The clinical features of these homozygote patients with PD did not differ from those of typical PD.

CONCLUSIONS

The homozygote polymorphism of 7048G7049 in intron 6 of the Nurr1 gene is associated with typical PD.

Differential expression of two distinct forms of mRNA encoding members of a dipeptidyl aminopeptidase family

We have identified two cDNAs encoding dipeptidyl aminopeptidase-like proteins (DPPXs) in both bovine and rat brains that have different N-terminal cytoplasmic domains but share an identical transmembrane domain and a long C-terminal extracellular domain. In both species, one of the cDNAs encodes a protein (designated DPPX-S) of 803 amino acid residues with a short cytoplasmic domain of 32 amino acids, and the other cDNA encodes a protein (designated DPPX-L) with a longer cytoplasmic domain--the bovine cDNA encodes 92 amino acids and the rat cDNA encodes 88 amino acids. The membrane topology of DPPX-S and -L is similar to that of other transmembrane peptidases, and DPPX-S share approximately 30% identity and 50% similarity with reported yeast and rat liver dipeptidyl aminopeptidase amino acid sequences, suggesting that DPPX is a member of the dipeptidyl aminopeptidase family. DPPX-S mRNA is expressed in brain and some peripheral tissues including kidney, ovary, and testis; in contrast, DPPX-L mRNA is expressed almost exclusively in brain. No transcripts for either form are found in heart, liver, or spleen. In situ hybridization studies show that the two transcripts have different distributions in the brain. DPPX-L mRNA is expressed in limited regions of brain with the highest level of expression in the medial habenula. More widespread expression is seen for DPPX-S mRNA. The differential distribution of mRNAs for the DPPX-S and -L suggests that these proteins are involved in the metabolism of certain localized peptides and that the cytoplasmic domain may play a key role in determining the physiological specificity of DPPX.

Mechanical ventilation and high-efficiency vacuum cleaning: A combined strategy of mite and mite allergen reduction in the control of mite-sensitive asthma

BACKGROUND

The relationship between exposure to house dust mite (HDM) allergens and prevalence of sensitization to these allergens in patients with asthma has been confirmed in many studies. Mite population growth is regulated by humidity. Reducing humidity and removing allergen by efficient vacuuming should control mite allergen and reduce symptoms.

OBJECTIVE

We sought to investigate the effect of mechanical ventilation and high-efficiency vacuuming on HDM numbers and Der p 1 concentrations in the homes of mite-sensitive asthmatic subjects and to evaluate the effect of any reductions on symptoms.

METHODS

The homes of 40 HDM-sensitive asthmatic subjects were randomized to receive (1) mechanical ventilation and a high-efficiency vacuum cleaner (HEVC); (2) mechanical ventilation alone; (3) an HEVC alone; and (4) no intervention. Homes and patients were monitored for 12 months. Change in absolute humidity, mite numbers, Der p 1 concentrations, lung function, bronchial hyperresponsiveness, and symptom scores were analyzed.

RESULTS

Homes with mechanical ventilation achieved significantly lower humidity levels than those without (P <.001), with an associated reduction of mite numbers (P <.05) and Der p 1 concentrations (P <.001 ¿in nanograms per gram, P =.006 ¿in milligrams per square meter) in bedroom carpets and some other mite sources in the ventilated areas of the homes. The addition of a vacuum cleaner enhanced this effect. There was a trend for an improvement in histamine PC(20) (P =.085) in the patients whose homes were ventilated.

CONCLUSION

The use of a mechanical ventilation system in suitable homes resulted in some reduction in numbers of HDM and Der p 1 concentrations. The addition of an HEVC slightly enhanced the effect but not sufficiently to see an improvement in symptoms.

Histone-histone propinquity by aldehyde fixation of chromatin

Histones have been fixed within the chromatin complex using either formaldehyde or glutaraldehyde. Evidence is presented which argues that in short time periods formaldehyde fixation leads to the formation of reversible covalent bonds between histone and DNA. On the other hand, fixation of chromatin with glutaraldehyde leads initially to the formation of polymers of F1 histone, and at a later stage of multiple small oligomers of the remaining histones. There oligomers then increase in size until they become too large to detect by polyacrylamide gel electrophoresis. Exclusive formation of histone dimers or tetramers was not observed. The simplest model for histone distribution on DNA which encompasses these observations is one in which histones are organized as a fairly extensive linear overlapping array.

Clinico-immunologic aspects of botulinum toxin type B treatment of cervical dystonia

In this multicenter study of 100 patients with cervical dystonia, we examined the immunogenicity of botulinum toxin type B (BTX-B) and correlated the clinical response with the presence of blocking antibodies (Abs) using a novel mouse protection assay. One-third of the patients who were negative for BTX-B Abs at baseline became positive for BTX-B Abs at last visit. Thus, the high antigenicity of BTX-B limits its long-term efficacy.

Key neuroprotective role for endogenous adenosine A1 receptor activation during asphyxia in the fetal sheep

BACKGROUND AND PURPOSE

The fetus is well known to be able to survive prolonged exposure to asphyxia with minimal injury compared with older animals. We and others have observed a rapid suppression of EEG intensity with the onset of asphyxia, suggesting active inhibition that may be a major neuroprotective adaptation to asphyxia. Adenosine is a key regulator of cerebral metabolism in the fetus.

METHODS

We therefore tested the hypothesis that infusion of the specific adenosine A1 receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine (DPCPX), given before 10 minutes of profound asphyxia in near-term fetal sheep, would prevent neural inhibition and lead to increased brain damage.

RESULTS

DPCPX treatment was associated with a transient rise and delayed fall in EEG activity in response to cord occlusion (n=8) in contrast with a rapid and sustained suppression of EEG activity in controls (n=8). DPCPX was also associated with an earlier and greater increase in cortical impedance, reflecting earlier onset of primary cytotoxic edema, and a significantly smaller reduction in calculated cortical heat production after the start of cord occlusion. After reperfusion, DPCPX-treated fetuses but not controls developed delayed onset of seizures, which continued for 24 hours, and sustained greater selective hippocampal, striatal, and parasagittal neuronal loss after 72-hour recovery.

CONCLUSIONS

These data support the hypothesis that endogenous activation of the adenosine A1 receptor during severe asphyxia mediates the initial suppression of neural activity and is an important mechanism that protects the fetal brain.

Gas exchange and heart rate in the harbour porpoise, Phocoena phocoena

The respiratory physiology, heart rates and metabolic rates of two captive juvenile male harbour porpoises (both 28 kg) were measured using a rapid-response respiratory gas analysis system in the laboratory. Breath-hold durations in the laboratory (12 +/- 0.3 s, mean +/- SEM) were shorter than field observations, although a few breath-holds of over 40 s were recorded. The mean percentage time spent submerged was 89 +/- 0.4%. Relative to similarly-sized terrestrial mammals, the respiratory frequency was low (4.9 +/- 0.19 breaths.min-1) but with high tidal volumes (1.1 +/- 0.011), enabling a comparatively high minute rate of gas exchange. Oxygen consumption under these experimental conditions (247 +/- 13.8 ml O2.min-1) was 1.9-fold higher than predicted by standard scaling relations. These data together with an estimate of the total oxygen stores predicted an aerobic dive limit of 5.4 min. The peak end-tidal O2 values were related to the length of the previous breath-hold, demonstrating the increased oxygen uptake from the lung for the longer dives. Blood oxygen capacity was 23.5 +/- 1.0 ml.100 ml-1, and the oxygen affinity was high, enabling rapid oxygen loading during ventilation.

Systemic sclerosis and bilateral lung transplantation: a single centre experience

Lung involvement is the leading cause of death in systemic sclerosis (SSc), but lung transplantation (LT) for systemic disease remains controversial. Our objective was to comprehensively evaluate post-LT outcomes for SSc compared to idiopathic pulmonary fibrosis (IPF). We retrospectively evaluated bilateral LT recipients (LTRs) with SSc or IPF at our centre between January 1, 2003 and December 31, 2007. The primary end-point was all-cause mortality at 1 yr post-LT. Secondary end-points included assessments of acute rejection (AR), pulmonary function, infection and chronic rejection. 14 patients with SSc and 38 patients with IPF underwent LT. Apart from a younger SSc cohort (53.2 versus 58.8 yrs; p = 0.02), the two groups were well matched. 1-yr all-cause mortality was no different between SSc (6.6%) and IPF (13.1%) groups, after adjusting for age (p = 0.62). Rates of (AR) ≥2 were significantly increased for the SSc compared with the IPF group (hazard ratio (HR) 2.91; p = 0.007). Other end-points, including chronic rejection, infection and pulmonary function, showed no differences. SSc LTRs experience similar survival 1 yr post-LT when compared to IPF. AR rates may be significantly higher in the SSc group. Longer follow-up is necessary to determine the effects of gastrointestinal dysfunction and AR on late allograft function in SSc LTR.

Alterations of GABAA receptor subunit mRNA levels in the aging Fischer 344 rat inferior colliculus

The inhibitory neurotransmitter, gamma-aminobutyric acid (GABA) is critically involved in shaping neuronal responses to simple and complex acoustic stimuli in the central auditory structure, the inferior colliculus (IC). Studies in rat and human suggest that age-related changes in markers for GABA neurotransmission occur in the IC. In particular, these changes include findings indicative of an age-related increase in the efficacy/potency of GABA to inhibit ligand binding at the GABAA receptor picrotoxin site in the Fischer (F344) rat IC. Such changes in GABAA receptor modulation suggest the potential for an alteration in GABAA receptor subunit composition in the old rat IC. To test this idea, the present study used in situ hybridization to quantify age-related changes in GABAA receptor subunit mRNA levels in the three major subdivisions of the IC in the F344 rat: dorsal cortex (DCIC), external cortex (ECIC), and the central nucleus (CIC). In support of earlier findings of an age-related change in GABAA receptor modulation, the present study found: (1) GABAA receptor subunit mRNA levels were significantly altered in the IC of old rats, and (2) age-related changes in subunit levels appeared to be regionally selective and subunit specific. A highly significant increase in the level of the gamma 1 subunit mRNA was observed with little change in the levels of the alpha 1, beta 2, and gamma 2 subunit mRNAs. A nonstatistically significant increase in alpha 2 subunit mRNA was also observed. This observed increase in alpha 2 subunit mRNA could be important since previous expression studies have shown that the alpha 2 and gamma 1 subunits coassemble and are incorporated into GABAA receptors which appear to be more sensitive to GABA. If the observed changes in subunit mRNA levels with age correlate well with enhanced GABAA receptor function in the IC of old rats, this, in turn, may represent a compensatory mechanism in response to presynaptic GABAergic changes.

Placebo-controlled trial of lubiprostone for constipation associated with Parkinson disease

OBJECTIVE

To evaluate the efficacy and tolerability of lubiprostone (Amitiza) for constipation in Parkinson disease (PD) in a double-blind, randomized, controlled study.

METHODS

Patients with PD and clinically meaningful constipation (constipation rating scale score > 10 [range: 0-28]) were recruited from 2 academic movement disorder centers to participate in the study. After enrollment, patients were initially followed for 2 weeks and then were randomly assigned 1:1 to lubiprostone, and the dose was titrated up to 48 μg/day. They returned 4 weeks later for a final assessment. Data included stool diaries and global impressions (co-primary endpoints), demographics, Unified Parkinson's Disease Rating Scale scores, constipation scale scores, visual analog scale (VAS) scores, a stool diary, and adverse events.

RESULTS

Fifty-four subjects (39 male, mean age 67.0 ± 10.1 years, and mean duration of PD 8.3 ± 5.4 years) were randomly assigned to lubiprostone or placebo. One patient in the drug group discontinued the study because of logistics, and one patient in the placebo group discontinued the study because of lack of efficacy. A marked or very marked clinical global improvement was reported by 16 of 25 (64.0%) subjects receiving drug vs 5 of 27 (18.5%) subjects receiving placebo (p = 0.001). The constipation rating scale (p < 0.05), VAS (p = 0.001), and stools per day in the diary (p < 0.001) all improved with drug compared with placebo. Adverse events with drug were mild, most commonly intermittent loose stools.

CONCLUSION

In this randomized controlled trial, lubiprostone seemed to be well tolerated and effective for the short-term treatment of constipation in PD.

The relationship between body mass index and waist circumference: implications for estimates of the population prevalence of overweight

OBJECTIVE

Body mass index (BMI) based on self-reported height and weight is a systematically biased, but acceptable measure of adiposity and is commonly used in population surveys. Recent studies indicate that abdominal obesity is more strongly associated with obesity-related health problems than is adiposity measured by BMI. The purpose of this study was to determine the relationships of both measured and self-reported BMI with measured waist circumference in a randomly selected sample of Australian adults.

DESIGN

Cross-sectional survey with self-reported and laboratory-based measures of adiposity.

SUBJECTS

1140 randomly-selected Australian adults aged 18-78 y resident in the city of Adelaide, South Australia.

MEASUREMENTS

Data on self-reported and measured height and weight as well as measured waist circumference were drawn from the Pilot Survey of the Fitness of Australians database. The proportion of men and women with acceptable BMI (BMI</=25 kg/m2) and with excess abdominal adiposity (>/=94 cm for men and >/=80 cm for women) was determined. Differences in the prevalence of overweight based on BMI alone or BMI and waist circumference were also determined.

RESULTS

Compared with the prevalence based on self-reported BMI alone, the prevalence of overweight among men based on self-reported BMI and waist circumference combined was 2.4%, 5.3%, 19.1% and 7.5% greater for men aged 18-39 y, 40-59 y, 60-78 y and for all men, respectively. Among women, compared with the prevalence based on self-reported BMI alone, the prevalence of overweight based on the combined measures was 9.9%, 24.0%, 33.3% and 20.6% greater for women aged 18-39 y, 40-59 y, 60-78 y and for all women, respectively.

CONCLUSIONS

If waist circumference is used as the criterion, then the prevalence of overweight among Australian adults, and probably other Caucasian populations, may be significantly greater than indicated by surveys relying on self-reported height and weight. The development of valid self-reported measures of waist circumference for use in population surveys may allow more accurate epidemiological monitoring of overweight and obesity.

A double-blind, placebo-controlled and longitudinal study of riluzole in early Parkinson's disease

BACKGROUND

To the extent that excitotoxicity may play a role in the pathogenesis of certain neurodegenerative disorders, antagonists of glutamate, an excitatory neurotransmitter, should exert neuroprotective effects in these disorders, including Parkinson's disease (PD).

METHODS

Patients in early stages of PD, not previously treated with levodopa, were randomized to receive riluzole 50mg capsules orally, taken twice daily or a matching placebo. All subjects were evaluated at baseline (pre-treatment), at 1, 3 and 6 months (post-treatment), and following a 6-week washout. After the washout, all subjects were offered an enrollment in an open label, 1-year, extension study. The principal investigator (JJ), however, remained blinded to the original assignment during the entire study. The patients were assessed by the Unified Parkinson's Disease Rating Scale (UPDRS), Activities of Daily Living (ADL), Hoehn & Yahr (HY) stage, and Schwab and England (SE) ADL scale. The quantitative assessments included Movement Time (MT) and Reaction Time (RT). Additionally, the time to initiate dopaminergic therapy was assessed. Safety was determined at each visit by clinical history and examination, a panel of blood safety laboratory tests including complete blood count, chemistry profile, and liver function studies.

RESULTS

Twenty patients with a mean age of 62+/-9.02 (range: 46-73) years and mean duration of symptoms of 18+/-9.53 (range: 6-36) months were enrolled. One patient withdrew from the study because he needed more aggressive treatment of his symptoms. Analysis of the efficacy variables showed no meaningful symptomatic effect of riluzole on UPDRS score. Likewise, there was no significant change in the median HY stage, SE ADL rating, or the MT/RT. Seventeen patients (mean age 62+/-9.26) elected to continue in the open label extension study. Although the observed deterioration in UPDRS scores seemed to be more pronounced in the placebo group than in the riluzole group, the difference did not reach statistical significance. There was no statistically significant difference in the latency between enrollment and start of symptomatic therapy when patients initially treated with riluzole were compared to those initially treated with placebo (8.3 vs 9 months).

CONCLUSIONS

This pilot and extension study showed that riluzole, 100mg/day, was well tolerated in patients with early PD. No evidence of symptomatic effect of riluzole was observed. Because of the exploratory nature of the design and small size of the study, it was not possible to determine whether riluzole affected the natural history of PD. The encouraging results from our study, however, suggest that larger, longitudinal studies are warranted.

Do benefits and barriers differ by stage of adoption for colorectal cancer screening?

In 2003, over 148,300 people were expected to be diagnosed and 56,000 to die from colorectal cancer (CRC). First-degree relatives (FDRs) of people with colon cancer have a two- to eight-fold increased risk for CRC. Despite evidence that screening is effective, adherence with screening recommendations in this at-risk population is low. This study's purposes were to (1) identify perceived benefits and barriers of fecal occult blood testing (FOBT), sigmoidoscopy and colonoscopy, and (2) compare demographic characteristics and perceived benefits and barriers by stage of adoption for CRC screening. Participating FDRs (n = 257) completed a 40-min structured telephone interview. Despite high rates of agreement with the benefits of screening, most FDRs were not contemplating being screened. Of those 50 and older, most were in precontemplation for FOBT, sigmoidoscopy and colonoscopy. Older age was related to stage for FOBT and sigmoidoscopy, but not colonoscopy. Lack of provider recommendation also was related to stage. Consistent with theoretical predictions, precontemplators had (1) higher rates of endorsement of specific barriers to screening and (2) lower rates of endorsement of benefits than contemplators or actors. For morbidity and mortality reduction, participation in routine, periodic screening is imperative. These findings can guide development of screening-promoting interventions.