Sustained efficacy of a single intra-articular dose of FX006 in a rat model of repeated localized knee arthritis

OBJECTIVE

To evaluate the efficacy of a single intra-articular (IA) dose of FX006, an extended-release formulation of triamcinolone acetonide (TCA) in poly(lactic-co-glycolic acid) (PLGA) microspheres, on the sequelae of repeated episodes of synovitis.

DESIGN

Three flares of localized synovitis in the right knee of rats were induced over 4 weeks following a single IA injection of various doses of FX006, Kenalog(®) (TCA immediate release or TCA IR), or vehicle. Gait scores were employed to assess analgesic effect, and the joints were evaluated by histology at the end of the study. TCA plasma concentrations and corticosterone levels were monitored through the study.

RESULTS

A single IA dose of 0.28 mg FX006 significantly improved gait scores through all three reactivations. TCA IR at 0.06 mg (providing comparable plasma TCA exposure, 10-fold higher Cmax) demonstrated comparable benefit through the first reactivation only and reduced-to-no efficacy thereafter. Significantly improved histological joint scores were observed with effective doses of FX006 but not with TCA IR. Corticosterone levels were initially decreased following both TCA IR and FX006 treatment, but recovered by Day 14.

CONCLUSIONS

In localized, repeated synovitis in rats, sustained release of TCA following a single IA injection of FX006 significantly prolonged analgesia relative to TCA IR and significantly improved histological scores with no adverse effect on the HPA axis. Since synovitis can contribute to the pathophysiology of multiple joint diseases such as osteoarthritis (OA), RA and gout, FX006 may be an important treatment option for these conditions.

Brain proton magnetic resonance spectroscopy (1H-MRS) in Alzheimer's disease: changes after treatment with xanomeline, an M1 selective cholinergic agonist

OBJECTIVE

Higher than normal cellular levels of the phospholipid catabolic intermediate glycerophosphocholine have been found in postmortem brain tissue of persons with Alzheimer's disease. Proton magnetic resonance spectroscopy (1H-MRS) can detect a choline resonance that is largely due to glycerophosphocholine. The authors tested the hypothesis that treatment with xanomeline, an M1 selective muscarinic cholinergic agonist, would be associated with a decrease in the 1H-MRS choline resonance.

METHOD

Patients with mild to moderate Alzheimer's disease received placebo or xanomeline for 6 months. 1H-MRS spectra were collected at baseline and after treatment discontinuation for 12 patients, two taking placebo and 10 taking xanomeline at a dose of 25 mg t.i.d. (N = 4), 50 mg t.i.d. (N = 3), or 75 mg t.i.d. (N = 3).

RESULTS

For the combined group of patients taking xanomeline, there was a significant decrease in the choline/creatine ratio from baseline to endpoint.

CONCLUSIONS

Treatment of Alzheimer's disease with a cholinergic agonist is associated with a decrease in the MRS choline resonance. Xanomeline may reduce breakdown of cholinergic neuron membranes by reducing the cellular requirement for free choline for acetylcholine synthesis.

Protocols to demonstrate slowing of Alzheimer disease progression. Position paper from the International Working Group on Harmonization of Dementia Drug Guidelines. The Disease Progression Sub-Group

Two suggested clinical trial designs for assessing progression of Alzheimer disease are the randomized withdrawal design and the randomized start design. The most promising of these, the randomized start design, has the potential to demonstrate a delay in progression, but there remain problematic design, ethical, and statistical issues to be solved before the protocol can be used in a clinical trial. The development of biological markers of the disease process using neuroimaging or other measures also may provide a robust method of measuring disease progression and demonstrating the biological effect of a drug on the disease process.

Effects of central muscarinic-1 receptor stimulation on blood pressure regulation

Stimulation of central nervous system muscarinic-1 (M1) receptors in animals increases blood pressure, heart rate, and sympathetic outflow. In Alzheimer's disease, stimulation of central M1 receptors is reduced. When the oral formulation of the selective M1 agonist xanomeline was tested for the treatment of Alzheimer's disease, an increased incidence of syncope was observed. Therefore, we used Alzheimer's disease as a model of relative M1 deficiency to determine the effect of M1 receptor stimulation on blood pressure regulation in humans. Eight Alzheimer's patients and 6 healthy age- and sex-matched subjects underwent blood pressure, heart rate, forearm vascular resistance, plasma norepinephrine, and heart rate variability measurements during 90 minutes after ingestion of xanomeline or placebo, then during 45 minutes of head-up tilt. Alzheimer's patients were studied on three occasions: after placebo, the first dose of xanomeline, and 3 days of xanomeline. Normal subjects were studied after placebo and the first dose of xanomeline. A subset of 5 Alzheimer's patients was studied with the peripheral muscarinic antagonist methscopolamine. Oral xanomeline increased supine systolic and diastolic blood pressures in normal subjects and heart rate and plasma norepinephrine in all subjects. During the placebo tilt, 0 of 8 Alzheimer's patients and 2 of 6 healthy subjects developed near-syncope, and during the first-dose xanomeline tilt, 4 of 8 Alzheimer's patients and 3 of 6 healthy subjects had near-syncope. The maximal decrease in systolic blood pressure during tilt was greater with xanomeline than placebo in both groups (P<.03). Methscopolamine did not prevent xanomeline-induced hypotension. Central M1 receptor stimulation with the oral formulation of xanomeline in humans is associated with sympathetic stimulation under supine conditions and impaired baroreflex compensation during tilt. Alzheimer's patients, who presumably lack M1 receptor activity, may have a reduced risk of tilt-induced syncope compared with normal subjects. Both groups, however, have enhanced susceptibility to hypotension and syncope when M1 receptor activity is pharmacologically increased.

Components of image intensive diagnosis. Codifying visual features for effusion cytology

Components of visual assessment in the diagnosis of effusions were analyzed using relative operating characteristic. Diagnostic performance in the assessment of malignancy and the specification of metastatic origin was measured for two expert cytologists. The component of performance attributable to feature interpretation was measured in protocols which minimized the effects of clinical information and visual search in the decision process. Feature interpretation, as a process, contributed significantly to the evaluation of malignancy and marginally to the specification of metastatic origin. For each of these diagnostic tasks, the process of feature interpretation was codified in the construction of explicit models. The expert cytologists were asked to define a set of localized visual features that incorporate essential visual elements for diagnosis. These features were evaluated for a set of test cases, and regression models were constructed defining malignancy and metastatic origin. Relative operating characteristic analysis indicated that the predictive value of the models for diagnosis was very similar to the component of human performance attributable to feature interpretation.

Serial reconstruction of microtubular arrays within dendrites of the cat retinal ganglion cell: the cytoskeleton of a vertebrate dendrite

Serial reconstruction at the EM level of cat retinal ganglion cell dendrites reveals that: (1) the microtubular array is discontinuous, (2) microtubular endings are associated with smooth endoplasmic reticulum (SER), mitochondria, and plasma membrane, (3) individual microtubules always maintain a minimum distance from other microtubules (87 nm), SER (43 nm) and plasma membrane (69 nm), and (5) individual microtubules can 'wander' independent of adjacent microtubules throughout the dendritic volume. These observations, taken with some recent biochemical and immunohistochemical data by other workers, suggest that the microtubules are surrounded by a coat of high molecular weight, microtubular-associated proteins (HMW MAPs), which effectively creates a 90 nm tube around a central microtubular core. Our results suggest that bundles of these 'MAP-tubes' may serve as a major component of the dendritic cytoskeleton in the cat ganglion cells.

Microtubular disarray in cortical dendrites and neurobehavioral failure. II. Computer reconstruction of perturbed microtubular arrays

A previous report details morphological alterations in dendritic structure of cortical neurons in severe neurobehavioral retardation of unknown etiology. Using computer graphic techniques, the present study describes perturbations in the 3-dimensional character of the microtubular array, which correspond to degenerative change in dendritic geometry. In large proximal processes, two types of array have been reconstructed. Segmented microtubules may form a continuous helical swirl which underlies a bulge in the dendritic cylinder. Alternatively, small groups of microtubules, while maintaining orderly internal organization, may be disoriented with respect to the long axis of the process. In varicose regions of the dendrite the microtubular array is discontinuous. Microtubules course side by side through constructed regions, only to splay out and terminate within expanded regions. These pathological alterations in the microtubular array contrast sharply with the cortical dendritic microtubular array reconstructed from the normal adult mouse. Perturbation in those parameters which determine packing of microtubules within the dendritic process is also documented. In the pathological condition, microtubules lose the ability to exclude one another from close approach. The role of cross-linking molecules in maintaining the integrity of the microtubular array, and the role of microtubules in maintaining the geometry of the dendrite, are considered.

Microtubule disarray in cortical dendrites and neurobehavioral failure. I. Golgi and electron microscopic studies

Cortical biopsies obtained from 5 young children with severe neurobehavioral retardation of unknown etiology have been analyzed using Golgi and EM techniques. The normally cylindrical geometry of individual dendritic processes of pyramidal and non-pyramidal neurons is interrupted by the formation of distinct varicosities. While over 90% of observed cells are affected, the extent of varicosity formation varies from cell to cell and is most prominent in medium and small pyramidal cells. Varicosities may occur in the periphery only, or they may extend proximally to primary dendritic trunks. Accompanying changes include thin and irregular proximal processes, loss of dendritic spines, and predominance of long, thin tortuous spines. Ultrastructural analysis reveals characteristic changes in the cytoskeleton of these processes. Microtubules, within the larger proximal processes, twist and turn, relative to one another and relative to the long axis of the process. In varicose regions, microtubules course in roughly parallel array through constricted segments, only to splay away from one another on entering an expansion. Synapses are evident on constricted and expanded segments, as well as on spines. Alterations in dendritic structure of both pyramidal and non-pyramidal neurons may represent a primary target in the pathobiological process underlying neurobehavioral failure.

Growing optic nerve fibers follow neighbors during embryogenesis

The embryonic development of the optic nerve of the zebrafish, Brachydanio rerio, was studied by three-dimensional computer reconstruction from serial section electron micrographs. Growing fibers from retinal ganglion cells had growth cones in contact with more mature fibers from adjacent cell bodies. In the observed growth pattern, the optic fibers immediately behind the eye were ordered in such a way that the rectangular coordinates of the fiber positions were approximately proportional to the polar coordinates of their cell body positions. We suggest that this transformation is achieved by a simple following mechanism that translates the time and position of ganglion cell differentiation into a well-defined spatial organization within the optic nerve.