Novel ventriculo-peritoneal shunt in Alzheimer's disease cerebrospinal fluid biomarkers

Alzheimer's disease is an age-related dementia and its incidence is rising in developed countries as the population ages. Amyloid plaques and tau-rich neurofibrillary tangles are pathologic hallmarks of the disease. Treatment is symptomatic, consisting of compounds that block enzymatic acetylcholine degradation (acetylcholinesterase inhibitors). Cognitive benefits of the four approved antidementia drugs are typically modest and limited in duration. While Alzheimer's disease is undoubtedly multifactorial in cause, advancing age is the most important risk factor. Any robust theory of pathogenesis must account for the profound influence of age on the emergence of Alzheimer's disease. There is evidence that senescent changes in cerebrospinal fluid production, circulation, turnover and clearance of amyloid beta-peptides may be a key factor in the onset and progression of Alzheimer's disease. The effect of increasing cerebrospinal fluid circulation and turnover in Alzheimer's disease patients by implanting a novel, low-flow drainage system (COGNIshunt) has been studied and promising trends in cognitive stabilization and improvement in cerebrospinal fluid biomarkers have been found.

Reduction of brain lipid peroxidation by CSF drainage in Alzheimer's disease patients

Alzheimer's disease (AD) is associated with an increase in cerebrospinal fluid (CSF) levels of the isoprostane 8,12-iso-iPF2alpha-VI, a specific marker of in vivo lipid peroxidation. Poor cerebral clearance of end products of oxidative reactions via CSF circulation may contribute to and sustain ongoing stress. CSF drainage via a low-flow ventriculoperitoneal (VP) shunt may improve removal of these products, reducing oxidative stress. We quantified this biomarker in patients with AD undergoing to VP shunt placement at baseline and after one-year period. CSF sampling occurred at baseline and quarterly visits for one year. Levels of this isoprostane were determined simultaneously at the end of the study by gas chromatography negative ion chemical ionization mass spectrometry. Over one-year, CSF 8,12-iso-iPF2alpha-VI levels consistently decreased versus baseline (51% of initial level), while CSF protein, glucose, cell count and IgG concentrations remained within normal limits. This finding supports the hypothesis that improving CSF drainage enhances extra-cellular clearance of end products of oxidative reactions and lowers brain lipid peroxidation.

Intrathecal ziconotide in the treatment of refractory pain in patients with cancer or AIDS: a randomized controlled trial

CONTEXT

Ziconotide (formerly SNX-111) selectively blocks N-type voltage-sensitive calcium channels and may be effective in patients with pain that is refractory to opioid therapy or those with intolerable opioid-related adverse effects.

OBJECTIVE

To assess the safety and efficacy of intrathecal ziconotide in patients with pain that is refractory to conventional treatment.

DESIGN, SETTING, AND PATIENTS

Double-blind, placebo-controlled, randomized trial conducted from March 12, 1996, to July 11, 1998, at 32 study centers in the United States, Australia, and the Netherlands. Patients were 111 individuals ages 24 to 85 years with cancer or AIDS and a mean Visual Analog Scale of Pain Intensity (VASPI) score of 50 mm or greater. Patients were randomly assigned in a 2:1 ratio to receive ziconotide or placebo treatment.

INTERVENTIONS

Intrathecal ziconotide was titrated over 5 to 6 days, followed by a 5-day maintenance phase for responders and crossover of nonresponders to the opposite treatment group.

MAIN OUTCOME MEASURE

Mean percentage change in VASPI score from baseline to the end of the initial titration period.

RESULTS

Of the evaluable population, 67 (98.5%) of 68 patients receiving ziconotide and 38 (95%) of 40 patients receiving placebo were taking opioids at baseline (median morphine equivalent dosage of 300 mg/d for the ziconotide group and 600 mg/d for the placebo group; P =.63, based on mean values), and 36 had used intrathecal morphine. Mean (SD) VASPI scores were 73.6 (1.8) mm in the ziconotide group and 77.9 (2.3) mm in the placebo group (P =.18). Mean VASPI scores improved 53.1% (95% confidence interval [CI], 44.0%-62.2%) in the ziconotide group and 18.1% (95% CI, 4.8%-31.4%) in the placebo group (P<.001), with no loss of efficacy of ziconotide in the maintenance phase. Pain relief was moderate to complete in 52.9% of patients in the ziconotide group compared with 17.5% in the placebo group (P<.001). Five patients receiving ziconotide achieved complete pain relief, and 50.0% of patients receiving ziconotide responded to therapy compared with 17.5% of those receiving placebo (P =.001).

CONCLUSION

Intrathecal ziconotide provided clinically and statistically significant analgesia in patients with pain from cancer or AIDS.

Alzheimer's disease, normal-pressure hydrocephalus, and senescent changes in CSF circulatory physiology: a hypothesis

There is evidence that production and turnover of CSF help to clear toxic molecules such as amyloid-beta peptide (Abeta) from the interstitial-fluid space of the brain to the bloodstream. Two changes in CSF circulatory physiology have been noted as part of ageing: first, a trend towards lower CSF production, hence a decrease in CSF turnover; and second, greater resistance to CSF outflow. Our hypothesis is that, all else being equal, the initially dominant physiological change determines whether CSF circulatory failure manifests as Alzheimer's disease (AD) or as normal-pressure hydrocephalus (NPH). If CSF production failure predominates, AD develops. However, if resistance to CSF outflow predominates, NPH results. Once either disease process takes hold, the risk of the other disorder may rise. In AD, increased deposition of Abeta in the meninges leads to greater resistance to CSF outflow. In NPH, raised CSF pressure causes lower CSF production and less clearance of Abeta. The disorders may ultimately converge in vulnerable individuals, resulting in a hybrid as has been observed in several clinical series. We postulate a new nosological entity of CSF circulatory failure, with features of AD and NPH. NPH-AD may cover an important subset of patients who carry the diagnosis of either AD or NPH.

Topotecan in the treatment of acquired immunodeficiency syndrome-related progressive multifocal leukoencephalopathy

Progressive multifocal leukoencephalopathy (PML) affects about 1 in 20 individuals with the acquired immunodeficiency syndrome (AIDS) and has been associated with poor survival. This report describes the results of a phase II clinical trial using the drug topotecan, a semisynthetic analogue of camptothecan, administered to a cohort of subjects with AIDS-related PML. Data were evaluated on 11 of 12 subjects enrolled in the study. Three responded to therapy. Additionally, one patient was treated off-protocol and showed a response to treatment. Progression occurred after the first course; however, a partial response was noted after five courses. One study patient died from accidental overdose of topotecan. Overall, responders had higher pretreatment Karnofsky and lower Kurtzke expanded disability status scale scores than nonresponders. The most frequent toxicities were hematologic (anemia, neutropenia, and thrombocytopenia). Five patients had dose delays; all delays were due to hematologic adverse events. This study demonstrates that topotecan treatment may be associated with decreased lesion size and prolonged survival from the infection. Because of the small number of subjects in the study, further studies are required to evaluate the efficacy of topotecan in treating this disease.

Pharmacokinetics and pharmacodynamics of intrathecal ziconotide in chronic pain patients

The pharmacokinetics and pharmacodynamics of ziconotide were assessed over a 48-hour period following intrathecal (i.t.) administration (1, 5, 7.5, or 10 micrograms) to 22 patients with chronic, nonmalignant pain. Plasma and cerebrospinal fluid (CSF) samples were obtained over a 24-hour period. Analgesic efficacy was monitored using Visual Analog Scale of Pain Intensity (VASPI) and Category Pain Relief Scores (CPRS) measurements. Pharmacokinetic (PK) parameters were calculated by noncompartmental methods. Plasma ziconotide data were insufficient for PK calculations. In CSF, the median half-life of ziconotide was 4.5 hours. The median CSF clearance and volume of distribution were 0.26 mL/min and 99 mL, respectively. CSF pharmacokinetics of ziconotide were linear, based on cumulative exposure and peak CSF concentrations. A dose-related analgesia was observed. Pharmacokinetic-pharmacodynamic efficacy and safety analyses showed that higher CSF ziconotide concentrations were generally associated with analgesia and increased incidence of nervous system adverse events following a 1-hour i.t. infusion.

Assessment of low-flow CSF drainage as a treatment for AD: results of a randomized pilot study

OBJECTIVE

This prospective, randomized, controlled study was designed to investigate the safety, feasibility, and preliminary efficacy of long-term CSF drainage via a low-flow ventriculoperitoneal shunt in subjects suffering from AD.

METHODS

Twenty-nine subjects selected for probable AD (National Institute of Neurological and Communicative Diseases and Stroke-Alzheimer's Disease and Related Dementias Association criteria) were screened to exclude normal pressure hydrocephalus or other etiologies of dementia and randomized to treatment (shunt) or no treatment groups. The study endpoint was the comparison of group performance on psychometric testing at quarterly intervals for 1 year. Shunted subjects had CSF withdrawn for MAP-tau and Abeta((1-42)) assays at the same time intervals.

RESULTS

There was no mortality from the surgical procedure, and no patient sustained a subdural hematoma. Five notable postoperative adverse events, which resolved without permanent neurologic deficit, were reported in the shunt group. Group mean Mattis Dementia Rating Scale total scores showed little change over the year in the shunt-treatment group, in contrast to a decline in the control group (p = 0.06). Mini-Mental State Examination mean scores supported a trend in favor of shunt treatment (p = 0.1). There was a concomitant decrease in ventricular CSF concentrations of AD biomarkers MAP-tau and Abeta((1-42)).

CONCLUSIONS

The surgical procedure and the device are reasonably safe. Adverse events were consistent with shunt procedures for hydrocephalus in this older population. The endpoint data show a trend in favor of the treated group. A larger, randomized, double-blinded, controlled, clinical trial is underway.

Changes in monocyte/macrophage neurotoxicity in the era of HAART: implications for HIV-associated dementia

OBJECTIVE

To determine changes in CD14/CD69 cells of HIV seropositive patients with HIV-1 associated dementia (HAD) on highly active antiretroviral therapy (HAART) and to determine the effect of soluble factors from cultured monocyte/macrophage (M/M phi) on neural cell functional proteins.

DESIGN AND METHODS

Whole blood from patients with HAD, HIV seronegative subjects, and HIV seropositive subjects with no dementia (HIV-ND) was analyzed for CD14/CD69 cells using flow cytometry. M/M phi were isolated and cultured, and supernatants tested for neurotoxicity. Modulation of neural cell proteins and mitogen-activated protein kinases in response to supernatant exposure was examined by Western blot.

RESULTS

CD14/CD69 levels from HAART-treated HAD subjects were significantly elevated over those from HIV-ND subjects and controls. However, levels were significantly lower than those reported in similarly selected HAD subjects tested prior to the HAART era. Treatment of neural cells with M/M phi-derived culture supernatants from HAART-treated HAD subjects was not associated with cell death, but resulted in a trend towards lower activation of the JNK, AKT, and ERK kinases, decreased expression of SNAP-25, and increased expression of neurofilament light than was observed after treatment with HIV-ND M/M phi supernatants.

CONCLUSIONS

The clinical phenotype of HAD appears to be evolving from a subacute dementing disease to a more protracted disorder. Decreased CD14/CD69 levels may reflect changes in some aspects of the pathophysiology of brain injury in the era of HAART. Changes in neural cell signaling, structural and functional proteins may represent more subtle neurotoxicity, manifested in cell dysfunction rather than frank cell death.

A reverse transcriptase-polymerase chain reaction assay for detecting Highlands J virus

Highlands J (HJ) virus is an arbovirus frequently recovered at high rates in mosquitoes collected in the eastern United States. HJ virus is primarily a veterinary pathogen causing disease in domestic birds including turkeys, chickens, and partridges. It has an enzootic cycle similar to eastern equine encephalitis (EEE) virus and is often used as an indicator species in EEE surveillance programs. Current immunologic techniques to identify HJ virus are often inefficient and can involve cross-reactivity of antibodies. Therefore, we developed a molecular-based assay by a reverse transcriptase (RT)-polymerase chain reaction (PCR) technique. Primers were constructed from conserved sequences of the E1 coding region from 19 strains of HJ virus. PCR amplifications from serial dilutions of HJ virus-infected Vero cell culture supernatants indicated that this assay could detect viral RNA at concentrations of 10 plaque-forming units per reaction. Extracted RNAs from western equine encephalitis, EEE, LaCrosse, and Jamestown Canyon viruses were not detected with this assay. RNA extracted directly from the brain tissue of a dead house sparrow and from a pool of Culiseta mosquitoes yielded a PCR product of the expected size. The RT-PCR technique developed was both sensitive and specific for detecting HJ virus from infected cell culture supernatants, bird brain tissues, and mosquitoes. This new assay will permit rapid and accurate diagnosis of HJ virus, both enhancing surveillance activities for EEE transmission risk and monitoring infections in domestic poultry and wild birds.

Pharmacological frontiers in the treatment of AIDS dementia

Even in the era of highly active antiretroviral therapy, AIDS dementia remains an important and devastating complication of human immunodeficiency virus (HIV-1) infection. Based on the 1997 AIDS case rate of 56 per 100 000 population in the USA, a reasonable estimated incidence of AIDS dementia is 3-8 per 100000, similar to that of multiple sclerosis. The pharmacology of AIDS dementia has been dominated by antiretroviral therapies, the best studied of which is azidothymidine. New and specific therapies are needed to treat and prevent brain injury in the setting of HIV infection. Rational therapy has been limited by the absence of large, adequate and well-controlled clinical trials using neuroprotective agents or those with disease-modifying potential, as well as by an incomplete understanding of the pathophysiology of AIDS dementia. In this review, a summary of evidence-based hypotheses of HIV-associated brain injury is followed by information on current nonantiretroviral therapeutic trials and their scientific rationale.

A randomized, controlled trial of remacemide for motor fluctuations in Parkinson's disease

BACKGROUND

Preclinical studies suggest that glutamate antagonists help ameliorate motor fluctuations in patients with PD treated with levodopa.

METHODS

In a multicenter, randomized, double-blind, placebo-controlled, parallel-group, dose-ranging study, the authors assessed the safety, tolerability, and efficacy of the glutamate receptor blocker remacemide hydrochloride in 279 patients with motor fluctuations treated with levodopa. The primary objective was to assess the short-term tolerability and safety of four dosage levels of remacemide during 7 weeks of treatment. Patients were also monitored with home diaries and the Unified PD Rating Scale (UPDRS) to collect preliminary data on treatment efficacy.

RESULTS

Remacemide was well tolerated up to a dosage of 300 mg/d on a twice daily schedule and 600 mg/d on a four times daily schedule. The most common dosage-related adverse events were dizziness and nausea, as observed in previous studies of remacemide. The percent "on" time and motor UPDRS scores showed trends toward improvement in the patients treated with 150 and 300 mg/d remacemide compared with placebo-treated patients, although these improvements were not significant.

CONCLUSION

Remacemide is a safe and tolerable adjunct to dopaminergic therapy for patients with PD and motor fluctuations. Although this study had limited power to detect therapeutic effects, the observed improvement is consistent with studies of non-human primates with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-induced parkinsonian signs and symptoms. Additional studies are warranted to confirm these results over an extended period of observation, and to explore the potential neuroprotective effects of remacemide in slowing the progression of PD.

Fenoldopam, a dopamine agonist, for hypertensive emergency: a multicenter randomized trial. Fenoldopam Study Group

Despite successful therapies for chronic hypertension, hospital admissions for hypertensive emergency more than tripled between 1983 and 1992.

OBJECTIVE

To examine the safety and efficacy of fenoldopam, the first antihypertensive with selective and specific action on vascular dopamine (DA1) receptors, in a clinical trial involving emergency department patients with true hypertensive emergencies.

METHODS

Patients with a sustained diastolic blood pressure (DBP) of > or =120 mm Hg and evidence of target organ compromise were randomized in a double-blinded manner to one of four fixed doses of intravenous fenoldopam (0.01, 0.03, 0.1, or 0.3 microg/kg/min) for 24 hours. The primary endpoint was the magnitude of DBP reduction in each of the three higher-dose groups after four hours of fenoldopam treatment compared with the lowest-dose group.

RESULTS

One hundred seven participants from 21 centers were enrolled, and 94 patients received fenoldopam. Evidence of acute target-organ damage included new renal dysfunction or hematuria (50%), acute congestive heart failure or myocardial ischemia (48%), and papilledema or grade III-IV hypertensive retinopathy (34%). The DBP decreased in a dose-dependent fashion, with significant differences between the 0.1- and 0.3-microg/kg/min groups compared with the lowest-dose group. Treatment was well tolerated, and there were no deaths or serious adverse events during follow-up, up to 48 hours. All patients were successfully transitioned to oral or transdermal antihypertensives with maintenance of blood pressure control.

CONCLUSIONS

Fenoldopam safely and effectively lowers blood pressure in a dose-dependent manner in patients with hypertensive emergencies. Observations supporting potential risk factors for hypertensive emergency are discussed.

Ziconotide, a new N-type calcium channel blocker, administered intrathecally for acute postoperative pain

BACKGROUND AND OBJECTIVES

Voltage-sensitive calcium channel conductance is essential for the nervous system to signal a painful event. However, intrathecal administration of L-type calcium channel blockers does not provide analgesia. The present investigation was designed to assess the safety and analgesic efficacy of ziconotide, a new N-type calcium channel blocker, when administered intrathecally to patients with acute postoperative pain.

METHODS

This randomized, double-blind, pilot study included patients undergoing elective total abdominal hysterectomy, radical prostatectomy, or total hip replacement. After intrathecal injection of local anesthetic and before surgical incision, a continuous intrathecal infusion of either placebo or 1 of 2 doses of ziconotide (0.7 microg/h or 7.0 microg/h) was started and continued for 48 to 72 hours postoperatively. Primary and secondary efficacy variables were the mean daily patient controlled analgesia (PCA) morphine equivalent consumption and visual analog pain intensity (VASPI) scores, respectively.

RESULTS

Thirty patients received study drug; 26 were evaluable for efficacy. Mean daily PCA morphine equivalent consumption was less in patients receiving ziconotide than in placebo-treated patients, and the difference was statistically significant between 24 and 48 hours (P = .040). VASPI scores during the first 8 hours postoperatively were markedly lower in ziconotide-treated than in placebo-treated patients. In 4 of 6 patients receiving the high-dose of ziconotide (7 microg/h), adverse events, such as dizziness, blurred vision, nystagmus, and sedation contributed to study drug being discontinued after 24 hours. After ziconotide discontinuation, these symptoms resolved.

CONCLUSIONS

Ziconotide showed analgesic activity, as shown by decreased PCA morphine equivalent consumption and lower VASPI scores. Because of a favorable trend of decreased morphine consumption with an acceptable side-effect profile in the low-dose ziconotide group, 0.7 microg/h may be closer to the ideal dose than 7 microg/h. Large-scale studies are required to clarify this issue.

The effects of fenoldopam, a selective dopamine receptor agonist, on systemic and renal hemodynamics in normotensive subjects

OBJECTIVE

Acute renal failure, frequently a consequence of renal vasoconstriction and subsequent renal ischemia, is a common problem for which no proven preventive or therapeutic agents exist. Fenoldopam is a new, selective, dopamine-1 receptor agonist that causes both systemic and renal arteriolar vasodilation. In hypertensive patients, fenoldopam rapidly decreases blood pressure, increases renal blood flow, and maintains or improves the glomerular filtration rate. We sought to determine a dose of fenoldopam that increases renal blood flow without inducing hypotension in normotensive patients and to explore the role of volume status (sodium replete vs. deplete) in these effects.

DESIGN

Randomized, double-blind, placebo-controlled, cross-over study.

SETTING

Clinical research unit.

PATIENTS

Fourteen normal male volunteers.

INTERVENTIONS

Renal plasma flow (para-aminohippurate clearance) and glomerular filtration rate (inulin clearance) were measured during three fixed, escalating doses of fenoldopam (0.03, 0.1, and 0.3 Lg/kg/min) on both a high-sodium and a low-sodium diet.

MEASUREMENTS AND MAIN RESULTS

Fenoldopam significantly increased renal plasma flow in a dose-dependent manner compared with placebo: 670 + 148 vs. 576 + 85 mUmin at 0.03 iLg/kg/min; 777 + 172 vs. 579 + 80 mUmin at 0.1 tig/kg/min; and 784 + 170 vs. 592 + 165 mUmin at 0.3 ilg/kg/min (p < .05 fenoldopam vs. placebo at all three doses). Glomerular filtration rate was maintained. At the lowest dose (i.e., 0.03 ILg/kg/min), significant renal blood flow increases occurred without changes in systemic blood pressure or heart rate. At 0.1 and 0.3 Lgl/kg/ min, systolic blood pressure did not change, but diastolic blood pressure was slightly lower in the fenoldopam group than in the placebo group: 62.5 + 6.4 vs. 63.6 + 2.6 mm Hg, respectively, at 0.3 tg/kg/min (p < .05). None of the effects of fenoldopam were altered by volume status.

CONCLUSIONS

Fenoldopam increased renal blood flow in a dose-dependent manner compared with placebo, and, at the lowest dose, significantly increased renal blood flow occurred without changes in systemic blood pressure or heart rate. These findings will be useful in designing future studies exploring the role of fenoldopam in preventing or treating renal failure in patients who are not hypertensive.

Toward earlier diagnosis of amyotrophic lateral sclerosis: revised criteria. rhCNTF ALS Study Group

We modified the World Federation of Neurology (WFN) diagnostic criteria for ALS to facilitate early diagnosis and used these criteria for enrollment of ALS patients in a clinical trial. The criteria developed required lower motor neuron (LMN) involvement in at least two limbs and upper motor neuron involvement in at least one region (bulbar, cervical, or lumbosacral). The EMG finding of fibrillation potentials was required for evidence of LMN involvement. Electrodiagnostic studies, neuroimaging, and laboratory studies were also used to exclude disorders that might mimic ALS. Using these criteria, the diagnosis of ALS was made at a mean time of 9.7 months from onset of symptoms, which compares favorably with the 12-month period cited in the literature. Using clinical assessment at completion of the trial, the diagnosis of ALS was believed to be accurate in those patients entered in the trial. However, pathologic confirmation of the diagnosis of ALS was not obtained. Based on our preliminary experience, we propose that these ALS diagnostic criteria will facilitate early diagnosis of ALS. Future studies should prospectively compare these criteria with the WFN criteria currently in use.

The management of severe chronic pain with a focus on new treatment modalities

Pain is the most common reason for consultation with a physician, but because pain is not objectively measurable, it is often neglected or underestimated. Chronic, severe pain is a major complication of cancer and HIV-1 infection. Current therapy typically employs stepwise treatment first with nonopioid analgesics, followed by weak and then strong opioids. Nevertheless, treatment can be limited both by side effects and by the development of tolerance, and patients with neuropathic pain are often resistant to all conventional therapies. Much has been learned about the neuroanatomy and physiology of both acute and chronic pain. Drugs now being developed, such as alpha(2)-receptor agonists, the N-type calcium channel blocker, SNX-111 and NMDA antagonists, take advantage of current knowledge of the neurochemistry of pain transduction and target neurotransmitter modulation as a means of achieving analgesia. These new drugs and alternative administration methods, such as intraspinal drug delivery and preemptive analgesia for postoperative pain, should add substantially to the current analgesic armamentarium.

Motor complications of chronic levodopa therapy in Parkinson's disease

We report on motor complications of chronic levodopa therapy among 811 levodopa-responsive patients with idiopathic Parkinson's disease (PD), stratified by duration after diagnosis. Predictable "offs" were noted in 20.2% of patients in the first 5 years, in 58.3% after 15 years. Unpredictable or sudden offs and early morning dystonia were less common. Longer duration was associated with greater percentages of patients with off periods or dyskinesias (up to 70% after 15 years), although patients with 6-15 years' duration saw relatively little increase in frequency of those complications, and a minority of patients (approximately 30%) with duration into the second decade did not experience off periods or dyskinesia. Across groups, mean Hoehn and Yahr stage and daily levodopa dosage progressively increase (and mean Schwab and England disability ratings decrease), but more conservatively than in prior reports in the postlevodopa era. We note that with advancing PD duration, levodopa complications are more common, but in many cases there appear to be relatively stable periods in terms of levodopa dosage and disease severity, and a minority of patients will be relatively free of motor complications into the second decade of their disease.