Regional changes of ciliary neurotrophic factor and nerve growth factor levels in post mortem spinal cord and cerebral cortex from patients with motor disease.

Ciliary neurotrophic factor (CNTF) rescues motor neurons in animal models of injury and neurodegeneration, and disruption of the mouse CNTF gene results in motor neuron degeneration in mature adults. Glial cells increase nerve growth factor (NGF) expression in neuropathological conditions, and the sensory system can be affected in the amyotrophic lateral sclerosis (ALS) type of motor neuronic disease. We therefore studied CNTF and NGF levels in post mortem spinal cord and cerebral cortex from patients with ALS and matched controls. We report a marked decrease of CNTF in the ventral horn of spinal cord in ALS, with no change in cerebral motor cortex. In contrast, NGF levels were decreased in ALS cerebral motor cortex, where the corticospinal tract originates, but increased in the lateral column of spinal cord, which includes the region of corticospinal tract degeneration in ALS. Both CNTF and NGF levels were decreased in ALS dorsal spinal cord.

Arrest of motor neuron disease in wobbler mice cotreated with CNTF and BDNF.

Ciliary neurotrophic factor (CNTF) and brain-derived neurotrophic factor (BDNF) each promote the survival and differentiation of developing motor neurons, but do so through distinct cellular signaling pathways. Administration of either factor alone has been shown to slow, but not to arrest, progression of motor neuron dysfunction in wobbler mice, an animal model of motor neuron disease. Because CNTF and BDNF are known to synergize in vitro and in ovo, the efficacy of CNTF and BDNF cotreatment was tested in the same animal mode. Subcutaneous injection of the two factors on alternate days was found to arrest disease progression in wobbler mice for 1 month, as measured by several behavioral, physiological, and histological criteria.

Afferent projections to the rat locus coeruleus as determined by a retrograde tracing technique.

Afferent connections to the rat locus coeruleus (LC), which contains exclusively noradrenergic neurons, have been traced using the technique of retrograde transport of horseradish peroxidase (HRP). In order to ensure accurate placement of adequate amounts of HRP in the LC, a microiontophoretic delivery technique coupled with single cell recording was employed. The use of electro physiological "landmarks" as aids in placing the injections is described. Following HRP injections into the LC, forebrain structures containing labelled neurons included the insular cortex, the central nucleus of the amygdala, the medial, lateral and magnocellular preoptic areas, the bed nucleus of the stria terminalis, and the dorsomedial, paraventricular and lateral hypothalamic areas. In the brainstem reactive neurons were observed in the central grey substance, the reticular formation, the raphe, vestibular, solitary tract and lateral reticular nuclei. In particular, the areas of catecholamine cell groups A1, A2 and A5 appeared to contain many reactive cells. Labelled neurons were also observed in the fastigial nuclei and in the marginal zones of the dorsal horns of the spinal cord. This pattern of afferent innervation supports suggestions for a role for the LC in behavioral arousal mechanisms and autonomic regulation.

Dopamine sulfate in ventricular cerebrospinal fluid and motor function in Parkinson's disease.

We measured sequential plasma and CSF levodopa and CSF dopamine sulfate levels following a single dose of levodopa/carbidopa in two patients with advanced Parkinson's disease (PD). We obtained CSF from an Ommaya reservoir implanted in the lateral ventricle several months earlier at the time of transplantation of adrenal medulla to caudate nucleus and could detect dopamine only in its sulfconjugated form. Peak CSF levodopa and dopamine sulfate levels occurred 1 to 1.5 hours after peak plasma concentration of levodopa. The time course of clinical improvement and worsening correlated precisely with the appearance and disappearance of both levodopa and dopamine sulfate in the CSF. The precise correlation between CSF dopamine sulfate and levodopa indicates that in patients with advanced PD the brain retains some capacity to convert levodopa to dopamine. The transient nature of the correlation between motor fluctuations, CSF levodopa, and CSF dopamine sulfate is consistent with suggestions that in patients with advanced PD there is a diminished capacity to store dopamine synthesized from exogenous levodopa. Dopamine sulfate appears to be a useful index of the availability of dopamine in the parkinsonian brain.

Clinical significance of the relationship between O-methyldopa levels and levodopa intake.

A recent clinical trial of controlled-release carbidopa/levodopa preparation afforded us the opportunity to examine the effects of chronically increasing circulating 3-O-methyldopa (OMD) levels on the clinical response to levodopa. In patients taking standard Sinemet, both mean plasma OMD levels and the area under the plasma concentration-versus-time curve (AUC) obtained during 8-hour periods of blood sampling correlated highly with the total daily intake of levodopa. In patients taking the controlled-release formulation, the mean daily intake of levodopa was doubled. This, in turn, led to a doubling of the mean OMD level and its AUC, whereas the AUC for levodopa was unchanged. Despite the increase in circulating OMD there was no reduction in mobility in either the "on" or "off" conditions. Thus, doubling plasma OMD levels did not seem to interfere with brain uptake of levodopa sufficiently to cause a deterioration in its therapeutic efficacy in these patients.

A pharmacokinetic and pharmacodynamic comparison of Sinemet CR (50/200) and standard Sinemet (25/100).

Seventeen patients with advanced Parkinson's disease who had fluctuations in motor performance while taking standard Sinemet (STD) 25/100 underwent daylong pharmacokinetic and clinical observation studies while taking both STD and Sinemet CR, a new controlled-release formulation containing 50 mg carbidopa and 200 mg levodopa. During treatment with Sinemet CR, there was an increase in the interdose interval, a reduction in the number of medication doses taken each day, an increase in total "on" time, and a reduction in the number of "off" episodes. Total daily levodopa intake was greater with Sinemet CR, although the bioavailability of levodopa and carbidopa from the two preparations was equivalent. The variability in plasma levodopa levels was significantly less with Sinemet CR. The slower release of drug from Sinemet CR was reflected in a prolongation of the Tmax for levodopa and a prolongation of the interval from Tmax to the succeeding trough levodopa level. Clinically, peak antiparkinsonian effect occurred later and lasted longer with the CR preparation.

Prognostic indicators of survival in ALS. ALS CNTF Treatment Study Group.

We analyzed data from the 245-patient placebo group of the ALS CNTF Treatment Study Group study, a large, prospective, multicenter study of recombinant human ciliary neurotrophic factor to determine prognostic factors for length of survival in ALS. Variables examined included baseline demographic characteristics, indices of disease severity, pulmonary function, and clinical laboratory tests. Shorter survival was associated with greater age, lower percent-predicted forced vital capacity (FVC%), and lower serum chloride at study entry. A shorter interval from symptom onset to diagnosis of ALS and greater weight loss in the 2 months before study entry also predicted shortened survival times. The rate of muscle strength loss before study entry did not predict risk of mortality. Serum chloride, reflecting the degree of respiratory acidosis, was identified for the first time as being correlated with prognosis in ALS. The relationship between a patient's FVC% and the probability of survival is described.

Sustained enteral administration of levodopa increases and interrupted infusion decreases levodopa dose requirements.

We placed a 60-year-old man with Parkinson's disease and marked therapeutic response fluctuations on a continuous enteral infusion of levodopa. On around-the-clock infusion, motor performance declined, although the infusion rate was progressively increased. We therefore interrupted the infusion each night. The patient could then progressively reduce levodopa intake while remaining continuously "on." Continuous infusion of levodopa downregulates, and interrupted infusion can restore, and even enhance, the sensitivity of striatal dopamine receptors.

"Early" initiation of levodopa treatment does not promote the development of motor response fluctuations, dyskinesias, or dementia in Parkinson's disease.

We reviewed the histories of patients seen in a large Parkinson's disease clinic from 1983 to 1989 to determine if there is a relationship between the timing of initiation of levodopa therapy and the development of motor response fluctuations, dyskinesias, and dementia. There were no factors predisposing to the development of response fluctuations or dementia. Younger age at disease onset predisposed to the development of dyskinesia. Dyskinesias occurred in a greater proportion of patients in whom the initiation of levodopa therapy was delayed by more than 2 years from disease diagnosis than among those in whom treatment was started earlier. We thus failed to identify any adverse consequences of early levodopa treatment in our patient population.

Controlled-release levodopa/carbidopa. I. Sinemet CR3 treatment of response fluctuations in Parkinson's disease.

Eight Parkinson patients with response fluctuations completed an open-label trial of a controlled-release carbidopa/levodopa preparation (Sinemet CR3). At the end of 6 weeks, percent "on" time and mean interdose interval increased, the number of daily doses and "off" periods was decreased, and the variability of plasma levodopa levels and disability scores was reduced. However, response fluctuations continued to occur, day-to-day consistency was poor, and the bioavailability of levodopa appeared less than that of standard Sinemet. Overall benefit waned over the next 3 to 6 months. Oral controlled-release carbidopa/levodopa is capable of reducing fluctuations in plasma levodopa levels and clinical performance in Parkinson's disease. The response to this particular controlled-release formulation was suboptimal and unsustained.

Controlled-release levodopa/carbidopa. II. Sinemet CR4 treatment of response fluctuations in Parkinson's disease.

Sixteen patients with Parkinson's disease and therapeutic response fluctuations entered an open-label trial of a controlled-release carbidopa/levodopa preparation, Sinemet CR4. Sinemet CR4 behaved as a slow release preparation. At the end of 6 weeks CR4 treatment, there was an increase in percent "on" time and mean interdose interval; the number of daily doses and "off" periods were diminished and a slight reduction in the variability of plasma levodopa levels was observed. Overall benefit waned over the next 6 months, despite addition of standard levodopa or Sinemet to overcome the delayed onset of antiparkinsonian effect of CR4 which resulted from prolongation in the Tmax for levodopa. The major benefits of CR4 were reduction in off time and in the number of daily off periods, with fewer levodopa doses per day and prolongation of the interdose interval.

The effect of L-dopa infusions with and without phenylalanine challenges in parkinsonian patients: plasma and ventricular CSF L-dopa levels and clinical responses.

We monitored the motor response and plasma and ventricular CSF (CSFv) concentrations of L-dopa during IV infusions of L-dopa in two patients with advanced Parkinson's disease. Concentrations of L-dopa in CSFv mirrored, but lagged behind, those in plasma. In the fasting state, the duration, but not the magnitude, of the motor response was greater with increasing plasma and CSFv levels of L-dopa. During IV infusions of L-dopa following oral administration of phenylalanine, a large neutral amino acid that shares a transport system into the brain with L-dopa, the duration of the motor response was markedly attenuated despite undiminished CSFv levels of L-dopa. These observations suggest that either L-dopa entry into CSFv and the brain are differentially affected by phenylalanine or that phenylalanine affects other steps in the motor response. These observations demonstrate that, except in the fasting state, L-dopa in CSFv is not a reliable predictor of motor response.

Clinical pharmacokinetics of anti-parkinsonian drugs.

Of the neurological disorders, none can claim a battery of therapeutic agents based upon as rational a pharmacology as can Parkinson's disease. In this review, the clinical pharmacokinetics of the major classes of anti-Parkinsonian drugs is discussed. Although they are the oldest drugs in the anti-Parkinsonian armamentarium, little pharmacokinetic data are available regarding the anticholinergic and antihistaminic agents. Based on elimination half-lives of 10 to 18 hours, most could probably be effectively given on a twice-daily schedule. Amantadine is unique among anti-Parkinsonian agents both in lacking a clearly defined mechanism of action and in being eliminated from the body exclusively by renal excretion of unchanged drug. Thus the normal decline of renal function in the elderly Parkinsonian population becomes an important factor in avoiding potential drug toxicity. The pharmacokinetics and pharmacodynamics of levodopa are complex. Since it is an amino acid, it follows metabolic pathways and must compete for absorption and brain uptake with a number of large neutral amino acids. It has a short elimination half-life and, as Parkinson's disease progresses, the brain loses its capacity to store the drug and becomes dependent in a moment-to-moment fashion on plasma levodopa concentrations, creating therapeutic response fluctuations in over 50% of patients. Pharmacokinetic considerations in the management of these response fluctuations are discussed. The newest class of anti-Parkinsonian agents are the direct acting dopamine receptor agonists. These drugs, all derivatives of ergot, have more prolonged durations of anti-Parkinsonian action than levodopa. However, other than bromocriptine, clinical experience with members of this class of drugs is still limited.

Effects of clonidine on habituation and sensitization of acoustic startle in normal, decerebrate and locus coeruleus lesioned rats.

Rats were presented with startle-eliciting tones after injection of clonidine (0.01, 0.02, 0.04, 0.08, 0.5, 1.0 or 2.0 mg/kg) or saline. Clonidine potently depressed startle amplitude and the effect was monotonically related todose. Pretreatment with piperoxane (10 mg/kg) antagonized this effect but pretreatment with phentolamine (10 mg/kg) did not. Clonidine still depressed startle in acutely decerebrate rats and in rats with bilateral ablation of the locus coeruleus. Clonidine did not interfere with sensitization to background noise and did not interfere with the ability to startle but instead improved within-session habituation. The results represent one of the few instances in the literature where a drug appears to improve habituation without directly interfering with the ability to respond. The possibility that clonidine might affect startle by stimulating central epinephrine rather than norepinephrine receptors is discussed.

Endogenous NGF and CNTF levels in human peripheral nerve injury.

Nerve growth factor (NGF) is trophic to sensory and sympathetic fibres, and ciliary neurotrophic factor (CNTF) to motoneurones, in animal models of peripheral nerve injury: NGF excess produces hyperalgesia. In this first study of injured human nerves and sensory ganglia, we quantified and localized endogenous NGF and CNTF in 59 neonate and adult patients with brachial plexus and peripheral nerve injury. NGF levels were generally depleted in injured nerves, but relatively preserved acutely in nerve segments distal to injury. NGF immunostaining was observed in Schwann cells in distal nerve segments with pockets of high levels in some neuromas. CNTF levels and immunostaining in Schwann cells were markedly decreased distally within days of injury. We propose that early local administration of NGF and CNTF-like agents may help prevent degenerative changes in injured nerves, while at later stages local anti-NGF treatment (e.g. of some neuromas) may ameliorate chronic pain.

The physiological identification of pyramidal tract neurons within transplants in the rostral cortex taken from the occipital cortex during development.

Axons from neurons in the occipital cortex transiently extend to the pyramidal tract (PT) during the early postnatal development of rats. Normally, these axons are eliminated by the end of the third postnatal week. However, if a portion of fetal occipital cortex is transplanted to the parietofrontal region in newborn hosts then some neurons in the transplant will extend pyramidal tract axons and maintain them. Intracortical microstimulation and electrophysiological recording techniques were used to identify the physiological characteristics of the transplanted pyramidal tract cells and to determine if motor effects could be elicited from the occipital transplant. Microstimulation of the transplant did not reliably evoke movement but the low density and disarray of PT cells within the transplant might account for this. Recording from within the transplant revealed that the overall cell activity was depressed. We were able to identify neurons within the transplant which responded antidromically to stimulation of the pyramidal tract, indicating that their axons have the capacity to conduct impulses and are therefore likely to have developed some viable connections. The functional significance of such projections remains uncertain.

Performance of the Amyotrophic Lateral Sclerosis Functional Rating Scale (ALSFRS) in multicenter clinical trials.

The Amyotrophic Lateral Sclerosis Functional Rating Scale (ALSFRS) is a 10-item functional inventory which was devised for use in therapeutic trials in ALS. Each item is rated on a 0-4 scale by the patient and/or caregiver, yielding a maximum score of 40 points. The ALSFRS assesses patients' levels of self-sufficiency in areas of feeding, grooming, ambulation and communication. Rotated factor analysis of the ALSFRS found that the rating items group logically and consistently into four categories. The ALSFRS has been validated both cross-sectionally and longitudinally against muscle strength testing, the Schwab and England ADL rating scale, the Clinical Global Impression of Change (CGIC) scale, and independent assessments of patient's functional status. In this report, we use the data provided by the placebo patients who participated in the ALS CNTF Treatment Study (ACTS) to demonstrate the robustness, test-retest reliability and consistency of the ALSFRS as employed in a large, multicenter clinical trial.

The ALSFRS-R: a revised ALS functional rating scale that incorporates assessments of respiratory function. BDNF ALS Study Group (Phase III).

The ALS Functional Rating Scale (ALSFRS) is a validated rating instrument for monitoring the progression of disability in patients with amyotrophic lateral sclerosis (ALS). One weakness of the ALSFRS as originally designed was that it granted disproportionate weighting to limb and bulbar, as compared to respiratory, dysfunction. We have now validated a revised version of the ALSFRS, which incorporates additional assessments of dyspnea, orthopnea, and the need for ventilatory support. The Revised ALSFRS (ALSFRS-R) retains the properties of the original scale and shows strong internal consistency and construct validity. ALSFRS-R scores correlate significantly with quality of life as measured by the Sickness Impact Profile, indicating that the quality of function is a strong determinant of quality of life in ALS.

A retrospective study of percutaneous endoscopic gastrostomy in ALS patients during the BDNF and CNTF trials.

Percutaneous endoscopic gastrostomy (PEG) provides a reliable route for nutrition and hydration in ALS patients with dysphagia. We performed a retrospective analysis of the CNTF and BDNF databases to determine the clinical status of ALS patients within 30 days preceding PEG insertion. This analysis revealed an approximately 50% reduction of function across multiple measures of ALS disease status. A trend to earlier intervention with PEG was apparent upon review of published studies and the CNTF and BDNF studies. By comparing the rate of decline pre- and post-PEG, nutritional supplementation via PEG stabilized the weight loss experienced by patients. Death within 30 days post-PEG was associated with a marked reduction in forced vital capacity (FVC) and identified a group of ALS patients in whom PEG should be cautiously performed. These data emphasize the importance of sequential measurement of FVC in managing ALS patients to guide the timing of nutritional intervention with PEG.

Intrathecal ciliary neurotrophic factor delivery for treatment of amyotrophic lateral sclerosis (phase I trial).

OBJECTIVE: This Phase I trial of ciliary neurotrophic factor (CNTF) delivered intrathecally for the treatment of patients with amyotrophic lateral sclerosis was designed to determine the safety of this new mode of administration as well as the pharmacokinetics and drug distribution. METHODS: CNTF was administered using a drug pump implanted into the lumbar subarachnoid space in each of four patients with amyotrophic lateral sclerosis. Escalating doses (0.4, 0.8, 1.6, 4, and 8 micrograms/h) were infused for 48 hours per week in 2-week cycles until the highest tolerated dose was achieved. Patients were observed for side effects, and standardized muscle and respiratory function tests were performed. Cerebrospinal fluid (CSF) levels of CNTF were determined using simultaneous lumbar and cervical taps. Plasma and CSF levels of antibodies, CSF cells and protein, and routine blood chemistries were monitored, as were weight and vital signs. RESULTS: Pharmacokinetic studies of four patients demonstrated that the distribution and clearance of recombinant human (rH)CNTF are similar to those of many small, water-soluble agents (morphine, baclofen, clonidine) and that the steady-state concentration of rHCNTF at the cervical level was 18 to 36% of that at the lumbar level. Lumbar CSF levels were in the range of 44 to 1230 ng/ml. Intrathecally administered rHCNTF had different adverse effects than the systemically delivered drug. With intrathecal administration, no asthenia, fever, chills, nausea, weight loss, increased cough, or sputum production was found. All patients who received rHCNTF intrathecally experienced dose-related CSF pleocytosis (primarily lymphocytic) and rises in protein levels. No clinical signs of meningeal irritation, such as stiff neck, photophobias, or nausea, were seen. However, one patient who had lumbar spinal stenosis developed severe burning and cramping leg pain. A second patient developed a severe headache and leg and back cramping. No abnormal clinical chemistry or hematological findings were encountered. Plasma levels of rHCNTF were below detection. Antibodies to rHCNTF were found in the systemic circulation of only one patient. The gradual decline in motor strength and performance of standard skills did not improve or worsen. CONCLUSIONS: In this first trial of a recombinant neurotrophic factor to be administered intrathecally by drug pump, the CNTF was well distributed along the spinal canal. Pain syndromes (headache, radicular pain) that were dose-related occurred in two patients, but systemic side effects, which had been observed with subcutaneous rHCNTF, did not occur. Intrathecal drug pump delivery of neurotrophic factors may be the most appropriate way in which to test the efficacy of these high-molecular weight proteins, because high CSF levels can be achieved without significant systemic side effects.