Incidence, epidemiology, risk factors and prognosis of atrio-esophageal fistula following percutaneous catheter ablation. An exhaustive natiowide registry

Introduction

A rare but often fatal complication of atrial fibrillation (AF) ablation is the formation of an atrioesophageal fistula (AEF) whose true prevalence and risk factors remain obscure.

Objective

To determine incidence, epidemiology, risk factors and prognosis of AEF using a – as exhaustive as possible – nationwide survey

Method

All French centers performing AF ablation were identified and survey were sent concerning the habits, techniques of AF ablation and eventual cases of AEF.

Results

82 of the 103 centers (80%) performing ablation of AF in France were included in the study performing 129286 ablations from 2006 (93% of the total AF ablation in France). 33 AEF were declared (26 AEF and 4 esopericardial fistula) (0.026% risk per procedure) with a stable annual incidence over time, unchanged after the advent of thermal probe. Sensititvity of CT scan for AEF diagnosis was 81%. Mortality was 60%, significantly lower in case of surgical mangement (31 vs 93%, p=0.001). No case of AEF happened after cryoablation and only two AEF occurred in redo ablation. In multivariate analysis, lack of use of contact force catheters and the realization of posterior/roof ablation lines emerged as independent factors associated with the risk of AEF with OR 23.6 (95% CI [4.5; 21]) p=0.0002 and OR 3.7 (95% CI [1.1, 13]) p=0.04) while the lack of thermal probes remained of borderline significance.

Conclusion

The rate of AEF after AF ablation in a nationwide and well exhaustive survey can be evaluated to 0.026% with an annual incidence remaining stable over time. A normal CT scan does not rule out the diagnosis. Prognosis remains poor with a mortality of 60% and crucially dependant of immediate surgical correction.

Funding Acknowledgement

Type of funding source: None

Relations between voltage mapping and diagnosis and genetics in patients with arrhythmogenic right ventricular cardiomyopathy

Introduction

Relations between voltage mapping and diagnosis or genetic background in patients with arrhythmogenic right ventricular cardiomyopathy (ARVC) have not been investigated so far.

Objective

We investigate if diagnosis or genetic background were linked to voltage mapping in ARVC.

Method

70 patients with proved or suspected ARVC undergoing 3D endocardial mapping and genetic testing have been retrospectively included. Localisation and extension of bipolar low voltage areas were correlated to ARVC diagnosis and presence of a culprit mutation.

Results

44/70 fulfilled ARVC Task Force criteria and 25/70 had culprit mutations. Endocardial (38/44 vs 16/26, p=0.02) and especially infero-lateral scars (31/44 vs 9/26, p=0.003) were more often present in patients fulfilling Task force criteria vs suspected ARVC, with larger scars (area 23±27 vs 8±11 cm2, p=0.04, perimeter 17±10 vs 11±7 cm, p=0.03) (sensitivity 86%). Mutated patients had more infero-lateral (19/25 vs 21/45, p=0.01), multiple (12/20 vs 11/34, p=0.04) and larger scars (perimeter 21±10 vs 12±7 cm, p=0.01) vs non mutated patients. In patients with ARVC diagnosed according to the Task Force criteria, there was a trend toward more infero-lateral (p=0.09) and larger scars (p=0.08) in mutated cases. PKP2-mutated cases tended to have less ourflow tract (p=0.08) and less multiple scars (p=0.09) vs other mutations.

Conclusion

3D endocardial mapping could have an important role for ARVC diagnosis and may be able to detect minor forms with otherwise insufficiant criteria for diagnosis. More frequent and larger infero-lateral scars are present in mutated patients with bordeline differences according to the mutated genes.

Funding Acknowledgement

Type of funding source: None

Hybrid surgical ablation for persistent or long standing persistent atrial fibrillation: A French single centre experience

BACKGROUND

Hybrid ablation for the treatment of atrial fibrillation is a single combined procedure consisting in a minimally thoracoscopic surgical ablation followed by a catheter ablation. This promising technique is recommended in persistent atrial fibrillation according to the current guidelines but is not routinely performed in France, mainly due to the absence of reimbursement by the French National Health Insurance.

AIMS

The aim of this prospective and single-centre study was to analyse, for the first time in France, the feasibility, efficacy and complication rates of hybrid ablation in patients with persistent atrial fibrillation.

METHODS

Hybrid ablation was performed in 15 consecutive patients (13 men, mean age 61±6 years) with persistent (7 patients) or long standing persistent (8 patients) atrial fibrillation.

RESULTS

Hybrid ablation was completed in 14/15 patients. Eleven patients returned in sinus rhythm during the procedure. Two patients (13%) had major per-procedural complications and 2 had minor complications. During an average follow-up of 25±6 months, 6 patients (40%) underwent a redo catheter ablation because of atrial tachycardia, mainly peri-mitral atrial flutter. At 1 year follow up, 14/15 patients were in sinus rhythm, including 11 free of antiarrhythmic drugs.

Usefulness of interim analyses in portending study results in antipsychotic and antidepressant trials

It is unknown whether interim analyses portend final study results. Fatigue, pressure to complete trials and recruitment differences may mitigate against this. We examined the similarity of efficacy results of the first and second half of recruited patients to complete trials and explore possible intervening variables. Using data from the NewMeds repository of patient level data from placebo-controlled randomized trials of antipsychotics (AP) (22 studies, n=7056) and antidepressants (AD) (39 studies, n=12,217) we compared treatment effect size (placebo vs. active treatment) of the first and second half of patients recruited in completed trials. We found that in AP studies median difference in treatment effect between cohorts was -0.03, indicating that overall first and second cohorts yielded similar results. In AD studies, median difference between cohorts was 0.04, indicating that overall the second cohort had slightly larger active-placebo-difference. Overall, on average there were minimal differences in effect size between the first and the second cohorts, and in 30 of 39 trials interim results were a good estimate of the results on the 2nd cohort. In AD trials first and second cohort results were more similar when the proportion of patients per study centre and recruitment time of the two cohorts was similar. Results suggest that interim analyses in AD and AP studies may reliably serve to estimate ultimate effects and, at least in AD trials, are more accurate when the same sites are used to a similar extent and recruitment time of the two consequent cohorts is similar.

Statistics of flexible chain configurations

When Monte Carlo methods are employed to study the statistical dimensions of flexible polymer chains, it is necessary that the sampling be statistically unbiased. One Monte Carlo procedure is the so-called "slithering snake" technique, which has proved to be very useful. A question arises, however, as to how long it takes for a "slithering snake" to be completely regenerated to avoid biasing the samples around a particular configuration. It is demonstrated theoretically and verified by Monte Carlo studies that the number of iterations required to completely regenerate a sample polymer is a quadratic function of the chain length. This verification applies to chains in dilute solution but may not hold for bulk polymers.

Early onset anxiolytic efficacy after a single dose of pregabalin: double-blind, placebo- and active-comparator controlled evaluation using a dental anxiety model

To evaluate acute onset of anxiolytic activity using a dental anxiety model, 89 patients were randomised to double-blind single dose pregabalin 150 mg, alprazolam 0.5 mg or placebo 4 h before a scheduled dental procedure. A Dental Anxiety Total score >12 (moderate-to-severe) without meeting Diagnostic and Statistical Manual of Mental Disorders (Fourth edition) (DSM-IV) anxiety disorder criteria was required. Efficacy and safety, assessed 2, 2.5, 3, 3.5 and 4 h postdose, included 100 mm Visual Analogue Scale for Anxiety (VAS-Anxiety; primary outcome), 100 mm VAS-Sedation and Time-to-Onset of Action Scale (TOAS), a patient-rated anti-anxiety drug-benefit scale (no [0] to full benefit [10]). Mixed model analysis found significantly greater VAS-A improvement slopes for pregabalin (t = -2.47; P = 0.014) and alprazolam (t = -2.39; P = 0.018). There was a significant improvement versus placebo in the TOAS from 2 h through endpoint in alprazolam patients and from 3 h onward in pregabalin patients. Pregabalin produced significantly greater increases in VAS-Sedation versus placebo from 2.5 h through 4 h (2 h onward for alprazolam). Notably, there was a higher correlation between TOAS and VAS-Sedation (r = +0.58) than VAS-Anxiety (r = -0.50) on Spearman's analysis. The majority of Adverse Effects (AEs) were mild, and the most frequent for pregabalin, alprazolam, and placebo, respectively, were fatigue (N = 7, 7, 3), dizziness (N = 6, 3, 3), attention disturbance (N = 3, 1, 0), somnolence (N = 3, 0, 0), feeling abnormal (N = 0, 2, 0) and balance disorder (N = 0, 2, 0). These results suggest that onset of clinically meaningful anxiolytic effect after single-dose pregabalin occurs within the first 3-4 h. Additional research is needed to determine whether anxiolytic effect occurs in generalized anxiety disorder populations by day 1 or within 3-4 h post-first dose.

Is Speed of Onset of Anti-anxiety Efficacy with Pregabalin Influenced by Starting Dose?

Objective:

There appears to be no dose-response effect for pregabalin at doses of 300-600 mg, and a modest dose-response effect in the range of 150-300 mg. The goal of the current investigation was to determine the effect of the starting dose on the speed of onset of anxiolytic efficacy.

Methods:

Data were analyzed from 7 trials of outpatients with DSM-IV GAD and a HAM-A total score ≥18. Starting doses of pregabalin ranged from 100 mg (N=301) or 150 mg (N=104), to 200 mg (N=167) and 300 mg (N=388). Assessment of early improvement included the HAM-A total score and CGI-Severity and Improvement scores.

Results:

The mean Week 1 HAM-A change score was similar for a starting dose of 200 mg/d with no titration (-8.24) when compared to patients who started on 200 mg/d and then titrated up to 400 mg/d on Day 4 (-8.64). The mean Week 1 HAM-A change score was somewhat higher for patients started on 300 mg/d, and then titrated to 450 mg/d on Day 4/5 (-8.84) when compared to patients started on a lower (100/150 mg/d) dose and titrated on Day 5 to 400/450 mg/d (-7.32). Starting on a dose of 300 mg/d with no titration resulted in an intermediate Week 1 change score (-7.87). The interaction of starting dose and titration schedule with baseline anxiety severity will be summarized in detail.

Conclusion:

The initial dose of pregabalin appears to have only a weak effect on the speed of onset of anxiolytic improvement.

[Analysis of the interaction between nicotinic acetylcholine receptor and Na+,K(+)-ATPase in the rat skeletal muscle and the Torpedo electric organ membrane preparation]

The interaction between the nicotinic acetylcholine receptor and Na+,K(+)-ATPase described previously was further studied in isolated rat diaphragm and in a membrane preparation of Torpedo californica electric organ. Three specific agonists of the nicotinic receptor: acetylcholine, nicotine and carbamylcholine (100 nmol/L each), all hyperpolarized the non-synaptic membranes of muscle fibers by up to 4 mV. Competitive antagonists of nicotinic acetylcholine receptor, d-tubocurarine (2 mcmol/L) or alpha-bungarotoxin (5 nmol/L) completely blocked the acetylcholine-induced hyperpolarization indicating that the effect requires binding of the agonists to their specific sites. The noncompetitive antagonist, proadifen (5 mcmol/L), exerted no effect on the amplitude of hyperpolarized but decreased K0.5 for this effect from 28.3 +/- 3.6 nmol/L to 7.1 +/- 2.3 nmol/L. Involvement of the Na+,K(+)-ATPase was suggested by data demonstrating that three specific Na+,K(+)-ATPase inhibitors: ouabain, digoxin or marinobufagenin (100 nmol/L each), all inhibit the hyperpolarizing effect of acetylcholine. Acetylcholine did not affectation either the catalytic activity of the Na+,K(+)-ATPase purified from sheep kidney or the transport activity of the Na+,K(+)-ATPase in the rat erythrocytes, i. e. in preparations not containing acetylcholine receptors. Hence, acetylcholine does not directly affect the Na+,K(+)-ATPase. In a Torpedo membrane preparation, ouabain (< or = 100 nmol/L) increased the binding of the fluorescent ligand: Dansyl-C6-choline (DCC). No ouabain effect was observed either when the agonist binding sites of the receptor were occupied by 2 mmol/L carbamylcholine, or in the absence Mg2+, when the binding of ouabain to the Na+,K(+)-ATPase is negligible. These results indicate that ouabain only affects specific DCC binding and only when bound to the Na+,K(+)-ATPase. The data obtained suggest that, in two different systems, the interaction between the nicotinic acetylcholine receptor and the Na+,K(+)-ATPase specifically involve the ligand binding sites of these two proteins.

[Functional interaction between nicotinic cholinergic receptors and Na, K-ATPase in the skeletal muscles]

Acetylcholine (ACh) hyperpolarized the rat diaphragm muscle fibers by 4.5 +/- 0.8 mV (K0.5 = = 36 +/- 6 nmol/l). The AC-induced hyperpolarization was blocked by d-tubocurarine and ouabain in nanomolar concentrations. This effect of ACh was not observed in cultured C2C12 muscle cells and in Xenopus oocytes with expressed embryonic mouse muscle nicotinic acetylcholine receptors (nAChR) or with neuronal alpha 4 beta 2 nAChR. In membrane preparations from the Torpedo californica electric organ, containing both nAChR and Na, K-ATPase, 10 nmol/l ouabain modulated the binding kinetics of the cholinergic ligand dansyl-C6-choline to the nAChR. These results suggest that in-sensitive alpha 2 isoform) and nAChR in a state with high affinity to Ach and d-tubocurarine may form a functional complex in which binding of ACh to nAchR is coupled to activation of the Na, K-ATPase.

[Porcine kidney extract contains a specific inhibitor of the ouabain-sensitive alpha2-isoform of Na, K-ATPase present in rat diaphragm fibres]

In experiments on isolated rat diaphragm muscle, acetylcholine (100 nmol/l) hyperpolarized muscle fibres due to activation of the alpha 2 isoform of Na,K-ATPase. This hyperpolarization was blocked in a dose-dependent manner by ouabain (K0.5 = 8 +/- 4 nmol/l) as well as by a solution of porcine kidney extract (10 kDa cut-off filtration), with the K0.5 approximately equal to a 1:20,000-fold dilution. The inhibitory activity of the developed slowly over a period of 3 hours and, in contrast to ouabain, was still present after 1 hour of washing. Ouabain, but not the extract, inhibits Rb+ uptake in human erythrocytes that only express the alpha = 1 isoform of Na, K-ATPase. Our data suggest that in rat skeletal muscle the alpha 1 isoform of Na,K-ATPase is primarily responsible for ionic homeostasis, while the alpha 2 isoform provides a "regulatable" function and may be controlled by cholinergic stimulation and/or endogenous digitalis-like factors (EDLFs). Porcine kidney extract contains a factor (M. W. < 10 kDa) that selectively inhibits the rat alpha 2 isoform and differs from ouabain. Our experimental protocol can be used as a highly sensitive physiological assay for factors that selectively inhibit the alpha 2 isoform of Na,K-ATPase.

Feasibility of atmospheric pressure desorption/ionization on silicon mass spectrometry in analysis of drugs

The feasibility of atmospheric pressure desorption/ionization on silicon mass spectrometry (AP-DIOS-MS) for drug analysis was investigated. It was observed that only compounds with relative high proton affinity are efficiently ionized under AP-DIOS conditions. The limits of detection (LODs) achieved in MS mode with midazolam, propranolol, and angiotensin II were 80 fmol, 20 pmol, and 1 pmol, respectively. In MS/MS mode the LODs for midazolam and propranolol were 10 fmol and 5 pmol, respectively. The good linearity (r(2) > 0.991), linear dynamic range of 3 orders of magnitude, and reasonable repeatability showed that the method is suitable for quantitative analysis.

Quantitative determination of 1 -hydroxypyrene in bovine urine samples using high-performance liquid chromatography with fluorescence and mass spectrometric detection

An analytical method was developed to determine quantitatively 1-hydroxypyrene (OHP) in bovine urine samples. The procedure includes an enzymatic hydrolysis to cleave the conjugated metabolite, an enrichment step using solid phase extraction with a non-polar rinse step and elution with dichloromethane. A final clean-up on silicagel was performed before high-performance liquid chromatography (HPLC) analysis and fluorescence detection. Alternatively, HPLC and electrospray ionization in the negative ion mode applying selective ion monitoring acquisition revealed to be a highly sensitive detection method allowing the quantitation of low pg of OHP in the urine samples. The method was successfully applied to the determination of OHP in bovine urine samples from animals living in urban and rural areas. Urine concentrations of OHP were significantly higher (median 8.6 microg l(-1)) of bovines living close to a highway.

The effect of relocation after a natural disaster

Twenty-five women remaining in a city devastated by an earthquake were compared with 24 relocated survivors and 25 comparison women. The women were administered a structured PTSD interview, the Hamilton Depression Scale, and SCL-90-R. The women in both exposed groups showed significantly more symptoms of avoidance, arousal, and total PTSD than the comparison group. The women in the relocated city had significantly higher depression scores than the women in the earthquake city. On the SCL-90-R, relocated women were most symptomatic and comparison group women were least symptomatic. Relocation after a disaster appears to be associated more with risk for depression than with PTSD in situations where recovery is delayed following the trauma.

Physically abused adolescents: behavior problems, functional impairment, and comparison of informants' reports

OBJECTIVE

This study, like earlier studies that focused on younger abused children, ascertained whether physically abused adolescents exhibited increased internalizing and externalizing behaviors. Relevance to pediatric practice is discussed.

DESIGN

A cross-sectional design was used to compare the behavior of physically abused adolescents and comparison adolescents using self-reports, parent reports, and teacher reports. The level of agreement among raters was also examined.

PARTICIPANTS

The subjects were 99 physically abused adolescents between the ages of 12 and 18 years, who were recruited from Child Protective Services. Comparison subjects were 99 community-recruited nonabused adolescents who were matched for age, gender, and income with the abused adolescents.

MEASURES

The behavior of the adolescents was assessed using the Child Behavior Checklist, and the comparable Youth Self-Report and Teacher Report Form, which are widely used measures of behavioral and emotional problems. The Child Global Assessment Scale was also used as a measure of functional impairment and of the need for mental health services.

RESULTS

Parents and teachers rated the problems of abused adolescents as significantly greater than the problems of nonabused adolescents on all checklist subscales. Abused adolescents reported significantly greater problems only on externalizing behavior subscales. In addition, based on interviewer ratings, physically abused adolescents exhibited significantly greater functional impairment.

CONCLUSIONS

Similar to previous research on abused children, physically abused adolescents exhibit externalizing and internalizing behavior problems and experience greater functional impairment. Parent, teacher, and adolescent reports of externalizing behaviors were similar, but physically abused adolescents reported fewer internalizing behaviors than did the other informants.

Oxidation of the skeletal muscle Ca2+ release channel alters calmodulin binding

This study presents evidence for a close relationship between the oxidation state of the skeletal muscle Ca2+ release channel (RyR1) and its ability to bind calmodulin (CaM). CaM enhances the activity of RyR1 in low Ca2+ and inhibits its activity in high Ca2+. Oxidation, which activates the channel, blocks the binding of 125I-labeled CaM at both micromolar and nanomolar Ca2+ concentrations. Conversely, bound CaM slows oxidation-induced cross-linking between subunits of the RyR1 tetramer. Alkylation of hyperreactive sulfhydryls (<3% of the total sulfhydryls) on RyR1 with N-ethylmaleimide completely blocks oxidant-induced intersubunit cross-linking and inhibits Ca2+-free 125I-CaM but not Ca2+/125I-CaM binding. These studies suggest that 1) the sites on RyR1 for binding apocalmodulin have features distinct from those of the Ca2+/CaM site, 2) oxidation may alter the activity of RyR1 in part by altering its interaction with CaM, and 3) CaM may protect RyR1 from oxidative modifications during periods of oxidative stress.

Posttraumatic stress disorder and family functioning in adolescent cancer

Twenty three adolescents with a history of cancer, 27 physically abused adolescents, and 23 healthy, nonabused adolescents were administered structured posttraumatic stress disorder (PTSD) interviews and self-report questionnaires regarding family functioning. Thirty five percent of adolescent cancer subjects met criteria for lifetime PTSD as compared to only 7% of the abused adolescents: 17% of the cancer subjects and 11% of the abuse subjects met criteria for current PTSD. Adolescents with cancer viewed their mothers and fathers as significantly more caring and more protective than the comparison and abused adolescents. Cancer subjects who met criteria for lifetime PTSD saw their families as significantly more chaotic than those who did not have PTSD. Eighty three percent of cancer subjects who had lifetime PTSD also had mothers who had PTSD.

Differential diagnosis of parkinsonism with [18F]fluorodeoxyglucose and PET

The clinical differentiation between typical idiopathic Parkinson's disease (IPD) and atypical parkinsonian disorders (APD) is complicated by the presence of signs and symptoms common to both forms of parkinsonism. Metabolic brain imaging with [18F]fluorodeoxyglucose (FDG) and positron emission tomography (PET) may be a useful adjunct in differentiating APD from IPD. To explore this possibility, we studied 48 parkinsonian patients suspected as having possible APD because of a deteriorating response to dopaminergic treatment, the development of autonomic dysfunction, or both. A group of 56 patients with likely IPD served as control subjects. We used quantitative FDG/PET to measure regional rates of cerebral glucose use in IPD and APD patients. We used discriminant analysis to categorize IPD and APD patients based on their regional metabolic data. We found that a linear combination of caudate, lentiform, and thalamic values accurately discriminated APD from IPD patients (p < 0.0001). Significant metabolic abnormalities were present in the striatum and the thalamus of 36 of 48 (75%) APD patients. Our findings show that measurements of regional glucose metabolism can be used to discriminate patients with suspected APD from their counterparts with classic IPD. FDG/PET may be a useful adjunct to the clinical examination in the differential diagnosis of parkinsonism.

Adolescent physical abuse and suicide attempts

OBJECTIVE

The rate of suicide attempts and the exposure to risk factors for suicide in an unselected sample of confirmed cases of physically abused adolescents recruited directly from the New York State Central Register for Nassau and Suffolk Counties was compared with those of a community sample of nonabused adolescents.

METHOD

Semistructured and structured diagnostic interviews were used in the assessment of psychopathology of adolescents and their parents

RESULTS

The proportion of adolescents attempting suicide did not differ for the two groups. However, the abused adolescents showed significantly greater exposure to risk factors for adolescent suicide, including family disintegration, and diagnoses of depression, disruptive behavior disorders, and substance abuse and dependence. Comparisons of the 8 physically abused adolescents who attempted suicide with the 91 who did not attempt suicide showed that the following factors were associated with significantly greater risk for suicide attempts: adolescents' perceptions of their families as lacking cohesiveness and maternal support, higher adolescent "hostility" ideation scores, adolescent diagnoses of disruptive disorders and conduct disorders, adolescent substance abuse/dependence, and exposure to a suicide attempt by a family member or a friend.

CONCLUSION

A transactional model of abuse, family and personal stressors, and the development of adolescent vulnerability leading to psychopathology is offered to explain the results.

A carboxy-terminal peptide of the alpha 1-subunit of the dihydropyridine receptor inhibits Ca(2+)-release channels

Excitation-contraction coupling in skeletal muscle is thought to involve a physical interaction between the alpha 1-subunit of the dihydropyridine receptor (DHPR) and the sarcoplasmic reticulum (SR) Ca(2+)-release channel (also known as the ryanodine receptor). Considerable evidence has accumulated to suggest that the cytoplasmic loop between domains II and III of the DHPR alpha 1-subunit is at least partially responsible for this interaction. Other parts of this subunit or other subunits may, however, contribute to the functional and/or structural coupling between these two proteins. A synthetic peptide corresponding to a conserved sequence located between amino acids 1487 and 1506 in the carboxy terminus of the alpha 1-subunit inhibits both [3H]ryanodine binding to skeletal and cardiac SR membranes and the activity of skeletal SR Ca(2+)-release channels reconstituted into planar lipid bilayers. A second, multiantigenic peptide synthesized to correspond to the same sequence inhibits both binding and channel activity at lower concentrations than the linear peptide. These peptides slow the rate at which [3H]ryanodine binds to its high-affinity binding site and decrease the rate at which [3H]ryanodine dissociates from this site. A third polypeptide synthesized in Escherichia coli and corresponding to amino acids 1381-1627 and encompassing the above sequence has similar effects. This portion of the alpha 1-subunit of the transverse tubule DHPR is therefore a candidate for contributing to the interaction of this protein with the Ca(2+)-release channel.

Development of a criteria set and a structured interview for disorders of extreme stress (SIDES)

Data regarding the development of a structured interview measuring alterations that may accompany extreme stress are presented. A list of 27 criteria often seen in response to extreme trauma and not addressed by DSM-IV criteria for posttraumatic stress disorder (PTSD) were generated based on a systematic review of the literature and a survey of 50 experts. A structured interview for disorders of extreme stress (SIDES) measuring the presence of these criteria was administered to 520 subjects as part of the DSM-IV PTSD field trials. Inter-rater reliability as measured by Kappa coefficients for lifetime Disorders of Extreme Stress was .81. Internal consistency using coefficient alpha ranged from .53 to .96. Results indicate that the SIDES is a useful tool for investigation of response to extremes stress.

Comparative nigrostriatal dopaminergic imaging with iodine-123-beta CIT-FP/SPECT and fluorine-18-FDOPA/PET

SPECT imaging of the dopamine transporter is now an alternative to PET in the quantification of nigrostriatal dopaminergic function. We compared [123I] beta CIT-FP/SPECT and [18F]FDOPA/PET in the assessment of nigrostriatal dopaminergic function in Parkinson's disease (PD) and normal aging.

METHODS

We studied 12 mildly affected PD patients (mean age: 61.0 +/- 13.2 yr; H&Y Stage I-II) with both [123I] beta CIT-FP and [18F]FDOPA. Fifteen normal volunteers (mean age: 45.5 +/- 22.1 yr) served as controls for both tracers. We measured the striato-occipital ratio (SOR) for both tracers at approximately 100 min postinjection.

RESULTS

We found a highly significant correlation between SOR measures obtained for both tracers (r = 0.79, p < 0.0001). In normal volunteers a significant age-related decline in striatal uptake was noted with [123I] beta CIT-FP (r = -0.56, p < 0.04) but not with [18F]FDOPA. SOR values for both tracers discriminated PD patients from controls with comparable accuracy (F[1,25] = 52.1 and 53.0, p < 0.0001 for [123I] beta CIT-FP and [18F]FDOPA, respectively). UPDRS motor ratings correlated with SOR values obtained by both imaging techniques (r = -0.69 and -0.60, p < 0.04 for [123I] beta CIT-FP and [18F]FDOPA, respectively).

CONCLUSION

These results indicate that [123I] beta CIT-FP/SPECT can provide quantitative descriptors of presynaptic dopaminergic function comparable to those obtained with [18F]FDOPA/PET.

Fluorodopa positron emission tomography with an inhibitor of catechol-O-methyltransferase: effect of the plasma 3-O-methyldopa fraction on data analysis

Flurodopa (FDOPA) is an analogue of L-di-hydroxyphenylalanine (L-dopa) used to assess the nigrostriatal dopamine system in vivo with positron emission tomography (PET). However, FDOPA/PET quantitation is complicated by the presence of the 3-O-methyl-FDOPA (3OMFD) fraction in brain and plasma. Pretreatment with entacapone (OR-611), a peripheral catechol O-methyl-transferase (COMT) inhibitor, greatly reduces the plasma 3OMFD fraction and provides an ideal situation to evaluate the contribution of the plasma 3OMFD fraction in several kinetic models of FDOPA uptake. We performed FDOPA/PET with and without the OR-611 preadministration in six Parkinson's disease (PD) patients. We measured the time-course of the plasma FDOPA and 3OMFD fractions using high-pressure liquid chromatography (HPLC). We calculated striato-occipital ratios (SOR), and estimated the striatal FDOPA uptake rate constant graphically using the plasma FDOPA and occipital tissue time activity curves (KiFD and KiOCC, respectively). We also estimated striatal dopa decarboxylase (DDC) activity (k3D) using a model incorporating independent measurements of 3OMFD transport kinetic rate constants. With the preadministration of OR-611, the pharmacological efficiency in plasma was prolonged significantly (21.1-37.7%; p < 0.01). We also observed significant mean elevations in SOR and KiOCC by 21.8 and 53.5%, respectively (p < 0.05). KiFD and k3D did not show significant change. We conclude that OR-611 prolongs the circulation time of FDOPA in the plasma but does not alter rate constants for striatal FDOPA uptake or decarboxylation.

The metabolic topography of normal aging

Normal aging is associated with the degeneration of specific neural systems. We used [18F] fluorodeoxyglucose (FDG)/positron emission tomography (PET) and a statistical model of regional covariation to explore the metabolic topography of this process. We calculated global and regional metabolic rates for glucose (GMR and rCMRglc) in two groups of normal subjects studied independently on different tomographs: Group 1--130 normal subjects (62 men and 68 women; range 21-90 years); Group 2--20 normal subjects (10 men and 10 women; range 24-78 years). In each of the two groups, the Scaled Subprofile Model (SSM) was applied to rCMRglc data to identify specific age-related profiles. The validity of these profiles as aging markers was assessed by correlating the associated subject scores with chronological age in both normal populations. SSM analysis disclosed two significant topographic profiles associated with aging. The first topographic profile, extracted in an analysis of group 1 normals, was characterized by relative frontal hypometabolism associated with covariate metabolic increases in the parietooccipital association areas, basal ganglia, mid-brain, and cerebellum. Subject scores for this profile correlated significantly with age in both normal groups (R2 = 0.48 and 0.33, p < 0.0001 for groups 1 and 2, respectively). Because of clinical similarities between normal motoric aging and parkinsonism, we explored the possibility of shared elements in the metabolic topography of both processes. We performed a combined group SSM analysis of the 20 group 2 normals and 22 age-matched Parkinson's disease patients, and identified another aging-related topographic profile. This profile was characterized by relative basal ganglia hypermetabolism associated with covariate decreases in frontal premotor cortex. Subject scores for this profile also correlated significantly with age in both normal groups (group 1: R2 = 0.30, p < 0.00001; group 2: R2 = 0.59, p < 0.01). Healthy aging is associated with reproducible topographic covariation profiles associated with specific neural systems. FDG/PET may provide a useful metabolic marker of the normal aging process.

Relocation after a disaster: posttraumatic stress disorder in Armenia after the earthquake

OBJECTIVE

To explore the relationship between exposure to the earthquake in Armenia on December 7, 1988, and relocation from the disaster zone, and the subsequent development of posttraumatic stress disorder (PTSD), depression, and behavioral difficulties in children.

METHOD

The PTSD module of the Diagnostic Interview for Children and Adolescents-Revised and the Depression Self-Rating Scale were administered to 25 children, aged 11 through 13 years, who had high exposure to the earthquake and remained in the earthquake city. They were compared with a demographically similar group of 24 children exposed to the earthquake who were relocated to another city after the earthquake and 25 nonexposed children. For each child the mothers responded to the Child Behavior Checklist and the teachers responded to the Teacher's Report Form.

RESULTS

The hypothesis that relocated children would present with less PTSD, depression, and behavioral problems was not confirmed. Both groups of children with high exposure to the earthquake, one remaining in the earthquake city and one relocating, demonstrated significantly higher rates of PTSD, depression, and behavioral difficulties than the comparison group. There were no differences between the relocated children and those who remained in the earthquake zone.

CONCLUSION

Children who were relocated after a natural disaster did no worse than children who remained in the disaster zone. Relocation should be considered as an alternative after catastrophic natural disasters in situations where resources are so limited that rebuilding cannot take place for an indefinite period of time.

Identification of PTSD in cancer survivors

The authors measured the rate and determinants of posttraumatic stress disorder (PTSD) in a group of cancer survivors. Patients who had a history of cancer diagnosis with at least 3 years since diagnosis, receiving no active treatment, such as chemotherapy or radiation, were interviewed (N = 27). Patients, who were part of the DSM-IV PTSD field trial, were compared with a community-based control group matched for age and socioeconomic status. One member of the survivor group (4%) and no members of the control group met criteria for current PTSD (NS). Six of the survivors (22%) and no control subjects met lifetime criteria (P < 0.02). Cancer patients have a higher rate of PTSD than found in the community. Symptoms closely resemble those of individuals who have experienced other traumatic events.

Posttraumatic stress disorder in mothers of pediatric cancer survivors

Prevalence of posttraumatic stress disorder (PTSD) in 24 mothers of pediatric cancer survivors was compared with its prevalence among 23 mothers of healthy children. Significantly more mothers of pediatric cancer survivors were diagnosed with lifetime PTSD. Significant differences were also found in lifetime arousal, as well as current and lifetime reexperience and avoidance symptom clusters. Significant difference existed in the distribution of the number of prediagnosis high-magnitude events experienced by the mothers diagnosed with current PTSD as compared with the prediagnosis experience of the mothers who were not diagnosed with current PTSD. Illness severity, level of perceived family and extrafamilial social support, and Symptom Checklist-90-Revised global severity index scores did not significantly differ in the PTSD-positive and PTSD-negative groups.

Combined FDOPA and 3OMFD PET studies in Parkinson's disease

PET has been used to quantify striatal 6-[18F]fluoro-L-dopa (FDOPA) uptake as a measure of presynaptic dopaminergic function. It has been suggested that the estimation of dopa-decarboxylation (DDC) rate, kD3, using a compartmental approach to dynamic FDOPA/PET data, can provide a better objective marker of parkinsonism. This modeling process, however, requires many assumptions to estimate DDC activity with acceptable errors.

METHODS

We combined FDOPA 3-O-methyl-fluorodopa PET studies on three normal subjects and five Parkinson's disease patients.

RESULTS

The contradicted modeling assumptions are: (a) the rate constants across the blood-brain barrier, KD1 and kD2, for 3OMFD and FDOPA were in similar range (ratio approximately equal to 1) and thus not equal to assumed values of KM1/KD1 of 2.3 derived from rat studies and applied to human FDOPA studies and (b) the KD1/kD2 ratio for frontal cortex was not equal to that for the striatum (0.70 +/- 0.15 versus 1.07 +/- 0.3; p < 0.002). Discriminant analyses indicate that simple estimates like the striatum-to-occipital ratio, or the graphically derived unidirectional transport rate constant (KiFD) separate normals from Parkinson's disease patients at least as accurately as estimates of striatal DDC activity (kD3).

CONCLUSION

Measurements of striatal DDC activity with dynamic FDOPA/PET and compartmental modeling may be based on incorrect assumptions. Even though such complex models yield microparameters that may be applicable to certain clinical research demands, they may produce misleading results in other experimental settings.

Clinical significance of striatal DOPA decarboxylase activity in Parkinson's disease

We performed dynamic PET studies with fluorodopa (FDOPA) in 9 normal volunteers and 16 patients with Parkinson's disease to investigate the applicability of dopa decarboxylase (DDC) activity measurements as useful markers of the parkinsonian disease process.

METHODS

From the 3-O-methyl-FDOPA (3OMFD)/PET studies, we obtained mean population values of the kinetic rate constants for 3OMFD (K1M = 0.0400 and k2M = 0.0420). We applied these values to calculate striatal DDC activity using the FDOPA compartmental model. We estimated k3D in this group using dynamic FDOPA-PET and population mean K1M and k2M values. We then applied the mean population K1M and k2M values to estimate k3D(pop) to a new group (6 normal volunteers and 11 patients) studied only with dynamic FDOPA-PET. In all FDOPA/PET studies, we calculated striatal uptake rate constants (KiFD) using a graphical method and also measured the striato-occipital ratio (SOR).

RESULTS

Although DDC activity has been postulated as a precise indicator of presynaptic nigrostriatal dopaminergic function, KiFD and SOR provided better between-group discrimination than did estimates of striatal DDC activity. KiFD and k3D(pop) both correlated significantly with quantitative disease severity ratings, with a similar degree of accuracy (r = 0.69 and 0.63 for k3D(pop) and KiFD, respectively; p < 0.01).

CONCLUSION

Although estimated striatal DDC activity correlates with clinical disability, this measure is comparably less effective for early diagnosis. We conclude that a simple estimate such as striatal KiFD is superior to k3D measurements for most clinical and research applications.

Early differential diagnosis of Parkinson's disease with 18F-fluorodeoxyglucose and positron emission tomography

Early-stage Parkinson's disease (EPD) is often clinically asymmetric. We used 18F-fluorodeoxyglucose (FDG) and PET to assess whether EPD can be detected by a characteristic pattern of regional metabolic asymmetry. To identify this pattern, we studied 10 EPD (Hoehn and Yahr stage I) patients (mean age 61.1 +/- 11.1 years) using 18F-FDG and PET to calculate regional metabolic rates for glucose. The scaled subprofile model (SSM) was applied to metabolic asymmetry measurements for the combined group of EPD patients and normal subjects to identify a specific covariation pattern that discriminated EPD patients from normal subjects. To determine whether this pattern could be used diagnostically, we studied a subsequent group of five presumptive EPD patients (mean age 50.9 +/- 18.3), five normal subjects (mean age 44.6 +/- 15.3), and nine patients with atypical drug-resistant early-stage parkinsonism (APD) (mean age 44.6 +/- 14.0). In each member of this prospective cohort, we calculated the expression of the EPD-related covariation pattern (subject scores) on a case-by-case basis. We also studied 11 of the EPD patients, five patients with APD, and 10 normal subjects with 18F-fluorodopa (FDOPA) and PET to measure presynaptic nigrostriatal dopaminergic function, and we assessed the accuracy of differential diagnosis with both PET methods using discrimination analysis. SSM analysis disclosed a significant topographic contrast profile characterized by covariate basal ganglia and thalamic asymmetries. Subject scores for this profile accurately discriminated EPD patients from normal subjects and APD patients (p < 0.0001). Group assignments into the normal or parkinsonian categories with FDG/PET were comparable to those achieved with FDOPA/PET, although APD and EPD patients were not differentiable by the latter method. Metabolic brain imaging with FDG/PET may be useful in the differential diagnosis of EPD.

Psychosocial correlates of chronic fatigue syndrome in adolescent girls

Behavior problems and family functioning were investigated in a sample of 10 adolescent girls with chronic fatigue syndrome (CFS), 10 matched healthy adolescent girls, and 10 adolescents with childhood cancer in remission. Based on the adolescent girls' reports, the CFS group had significantly higher scores than the cancer and healthy comparison adolescent girls on somatic complaints and also significantly higher scores than the cancer controls on internalizing symptoms and depression. Parent reports resulted in significantly higher scores in the CFS group than the adolescent girls from the healthy comparison groups on internalizing scores and somatic complaints. There were no significant differences on any family variables.

Prospective analysis of colorectal carcinoma. Determination of an age-site and stage relationship and the correlation of DNA index with clinicopathologic parameters

PURPOSE

A prospective study of colorectal cancer (1987-1991) using flow cytometry was performed to determine the relationship of age with DNA index (DNA-I), sites of disease, Dukes stage, grade, and survival.

METHODS

The flow cytometry was performed on 138 fresh, unfixed, surgical specimens using 4',6'-diamidino-2-phenylindole, a DNA fluorochrome.

RESULTS

The mean age was 66.9 (42.8 percent > or = 70; range, 22-92; median, 68) years, and 48.6 percent were female. The patients' stages were (in percent): A, 4.4; B, 53.0; C, 38.2; D, 4.4. Tumor grades of differentiation (in percent) were well, 14.4; moderate, 68.9; poor, 16.7; and sites (in percent) were: rectum, 19.6; sigmoid/left, 50.7; transverse/right, 29.0. Aneuploidy (DNA-I not equal to 1.0; CV, 3.5 percent) was found in 58.8 percent. Age (by decade of presentation) was compared with site and Dukes stage. Older patients had more transverse/right-sided lesions (P = 0.003). Patients with Dukes C and D tumors had a lower age (by decade of presentation) than patients with B2 lesions (P = 0.03). Age was not related to DNA-I or grade or DNA-I with sex, grade, site, stage, or survival (P > 0.05).

CONCLUSIONS

This prospective study suggests that colorectal cancer tends to present at an earlier stage and in the more proximal colon in the older population. Because right-sided lesions are beyond the reach of sigmoidoscopy, these findings have prognostic and screening implications.

Relationship of glycosylated hemoglobin, fetal macrosomia, and birthweight macrosomia

Previous studies have shown that glycosylated hemoglobin (Hb A1C) once elevated correlated with fetal malformations, poor perinatal outcome, and macrosomia. To determine whether Hb A1C was related to fetal diabetic complications such as polyhydramnois, fetal macrosomia, and fat line detected on ultrasonographic evaluation, 66 diabetic patient, types I, II, and III, were followed longitudinally. These ultrasound markers were further assessed regarding the reliability of predicting birthweight macrosomia. Fetal macrosomia and birthweight macrosomia were defined by weight greater than the 90th percentile for gestational age based on the Williams growth curve. The Hb A1C values were compared to women with and without fetal diabetic complications. Fetal diabetic complications occurred in 13 (20%) of the cases and birthweight macrosomia occurred in 19 (29%) of the cases. Of those 13 women with fetal diabetic complications, 11 (85%) had Hb A1C greater than 6.3%. This level was significantly different in women with the ultrasound markers vs those without. Ultrasound-determined macrosomia in predicting birthweight macrosomia has a sensitivity, specificity, positive and negative predictive values of 53%, 94%, 77%, and 83%, respectively. There is a critical level of Hb A1C at which ultrasound fetal diabetic markers were observed; this level is greater than 6.3%. We conclude that there is a target level of glycemic control that one must avoid to prevent birthweight macrosomia.

Input functions for 6-[fluorine-18]fluorodopa quantitation in parkinsonism: comparative studies and clinical correlations

PET has been used to quantify striatal 6-[18F]fluoro-L-dopa (FDOPA) uptake as a measure of presynaptic dopaminergic function. Striatal FDOPA uptake rate constants (Ki) can be calculated using dynamic PET imaging with measurements of the plasma FDOPA input function determined either directly or by several estimation procedures.

METHODS

We assessed the comparative clinical utility of these methods by calculating the striato-occipital ratio (SOR) and striatal Ki values in 12 patients with mild to moderate PD and 12 age-matched normal volunteers. The plasma FDOPA time-activity curve (KiFD); the plasma 18F time-activity curve (KiP); the occipital time-activity curve (KiOCC); and a simplified population-derived FDOPA input function (KiEFD) were used to calculate striatal Ki.

RESULTS

Mean values for all striatal Ki estimates and SOR were significantly lower in the PD group. Although all measured parameters discriminated PD patients from normals, KiFD and KiEFD provided the best between-group separation. KiFD, KiEFD and KiOCC measures correlated significantly with quantitative disease severity ratings, although KiFD predicted quantitative clinical disability most accurately.

CONCLUSION

These results suggest that KiFD may be an optimal marker of the parkinsonian disease process. KiEFD may be a useful alternative to KiFD for most clinical research applications.

Post-traumatic stress disorder in physically abused adolescents

OBJECTIVE

In an investigation of the prevalence of post-traumatic stress disorder (PTSD), other Axis I psychiatric disorders, and social and behavioral difficulties, 27 physically abused adolescents were compared with 27 nonabused controls who were recruited through random-digit dialing procedures.

METHOD

The Structured Clinical Interview for Diagnosis (PTSD module), Kiddie-Schedule for Affective Disorders and Schizophrenia, and Youth Self-Report were administered to all subjects; mothers were interviewed regarding their adolescent's behavior using the Kiddie-Schedule for Affective Disorders and Schizophrenia for School-Age Children and Child Behavior Checklist.

RESULTS

The three physically abused adolescents who received a diagnosis of PTSD on the PTSD module of the Structured Clinical Interview for Diagnosis reported their PTSD symptoms were in reaction to extrafamilial sexual assaults and not to physical abuse. In contrast, the abused adolescents showed significantly higher prevalence rates of depression, conduct disorder, internalizing and externalizing behavior problems, and social deficits.

CONCLUSIONS

Findings suggest that physically abused adolescents may be more at risk for behavioral and social difficulties than for PTSD.

Immunosuppressive therapy in pediatric inflammatory bowel disease: results of a survey of the North American Society for Pediatric Gastroenterology and Nutrition. Subcommittee on Immunosuppressive Use of the Pediatric IBD Collaborative Research Forum

We report the results of a survey of the membership of the North American Society for Pediatric Gastroenterology and Nutrition designed to determine pediatric gastroenterologists' attitudes toward the use of immunosuppressive therapy for inflammatory bowel disease (IBD), and to assess how these medications are actually being used in the treatment of children with IBD. One hundred five physicians (27% of surveys) responded. Eighty-eight (84%) had prescribed 6-mercaptopurine and/or azathioprine for IBD, and 66 believed that they were effective. Only 12 had used cyclosporine and four methotrexate. All physicians who had used immunosuppressives in IBD had prescribed them for patients with Crohn's disease, but only 50% had prescribed them for ulcerative colitis. The predominant indications for use included intractable symptoms despite traditional medical therapy (92%) and for corticosteroid-sparing effects (86%). Potential toxicities of greatest concern included marrow and immune suppression and malignancy. The vast majority of responders were not certain what to recommend with respect to the use of immunosuppressive agents prior to and during pregnancy. A clinical database was compiled from 165 retrospective case reports submitted by 45 physicians (33 medical facilities). At the start of immunosuppressive therapy, patients were 15.3 +/- 4.0 yr of age, and 52% were Tanner IV-V. Eighty-one percent had Crohn's disease, 8% ulcerative colitis, and 11% indeterminant colitis. One hundred twenty-two were treated with 6-mercaptopurine, and 43 with azathioprine. Five also received cyclosporine concomitantly. Overall, 68% of patients treated with an immunosuppressive improved. Complications requiring discontinuation of immunosuppressive therapy occurred in 6% of patients. It appears that immunosuppressives are commonly used to treat children with IBD despite a paucity of data regarding their safety and efficacy in this age group. Controlled, prospective trials are warranted to better define the role of immunosuppressive therapy in pediatric IBD.

Ovarian cysts are common in premenarchal girls: a sonographic study of 101 children 2-12 years old

Previous studies of sonograms in premenarchal girls have reported the typical ovary to be homogeneous in echogenicity, with cysts an uncommon finding, particularly in children less than 6 years old. These studies found no macrocysts (cysts greater than 9 mm in greatest length) in patients less than 11 years old. This information contradicts published pathology studies and our sonographic experience. The goal of this study was to determine the prevalence of cysts in the ovaries of premenarchal girls. The pelvic sonograms of 101 consecutive premenarchal girls between 2 and 12 years old, without known gynecologic or endocrinologic disease, were prospectively studied. One hundred fifty-five ovaries were adequately imaged in three dimensions. Ovaries were evaluated for the presence or absence of cysts (as defined by sonographic criteria), and the length of the cyst or of the largest cyst, if several were noted, was measured. Cysts were identified in 106 ovaries (68%). Cysts were seen in patients of all ages, particularly in the younger children (2-6 years old). Thirteen of the cysts, noted in 11 patients between 2 and 10 years old, were macrocysts. The typical sonographic appearance of the ovary in premenarchal girls is not homogeneous. Cysts are common in premenarchal girls between 2 and 12 years old and are the cause of the typical heterogeneous image. Macrocysts can be seen in healthy girls less than 11 years old.

Relationship of common laboratory parameters to the activity of Crohn's disease in children

The Pediatric Crohn's Disease Activity Index (PCDAI) has been proposed as a simple instrument to aid in the classification of patients by disease severity. The PCDAI includes subjective patient reporting of symptoms, physical examination, nutritional parameters, and several common laboratory tests (hematocrit, erythrocyte sedimentation rate, albumin). In this report we examine the relationship of each of the laboratory parameters to the PCDAI, as well as to a modified Harvey-Bradshaw Index score and physician global assessment of disease activity. Data were gathered from the clinical and laboratory observations from 133 children and adolescents at 12 pediatric gastroenterology centers in North America. A statistically significant relationship (p less than 0.05) was noted between each of the laboratory tests and the PCDAI for patients with either disease limited to the small bowel or in those with colonic involvement. For patients with disease limited to the small bowel, a statistically significant (p less than 0.05) relationship was also noted between the three laboratory parameters and the modified Harvey-Bradshaw Index and global assessment. For patients with large-bowel involvement, the erythrocyte sedimentation rate was statistically related to the modified Harvey-Bradshaw Index and global assessment (p less than 0.01), as was hematocrit to global assessment (p less than 0.01). Although the laboratory parameters used in the PCDAI appear to generally reflect disease activity in most patients, no single laboratory test is adequate to reflect disease activity in all patients. Future work will need to identify additional laboratory measures to reflect the inflammatory process and serve as important adjuncts in the assessment of disease activity.

Identification and characterization of a ouabain-like compound from human plasma

The plasma membrane sodium-potassium pumps that regulate intracellular sodium in most animal cells have specific, high-affinity receptors for the digitalis glycosides and their aglycones. This has fostered speculation that there is an endogenous ligand. We have purified and structurally identified by mass spectroscopy an endogenous substance from human plasma that binds with high affinity to this receptor and that is indistinguishable from the cardenolide ouabain. This human ouabain-like compound (OLC) displaces [3H]ouabain from its receptor, inhibits Na,K-ATPase and ouabain-sensitive 86Rb+ uptake, and has cardiotonic actions quantitatively similar to commercial ouabain. Immunoreactive OLC was detected in the plasma of many mammals, and high concentrations were found in the adrenals. The circulating OLC may modulate intracellular Na+ and affect numerous Na+ gradient-dependent processes including intracellular Ca2+ and pH homeostasis in many tissues. Furthermore, altered circulating levels of OLC may be associated with the pathogenesis of certain forms of hypertension.