Naftazone in advanced Parkinson's disease: An acute L-DOPA challenge randomized controlled trial

INTRODUCTION

There is an unmet need to better control motor complications in Parkinson's disease (PD). Naftazone, which exhibits glutamate release inhibition properties, has shown antiparkinsonian and antidyskinetic activity in preclinical models of PD and in a clinical proof of concept study.

METHODS

We conducted a double-blind randomized placebo-controlled cross-over trial in PD patients with motor fluctuations and dyskinesia testing naftazone 160 mg/day versus placebo for 14 days. The two co-primary endpoints were the area under curve (AUC) of motor (MDS-UPDRS part III) and dyskinesia (AIMS) scores during an acute levodopa challenge performed at the end of each period. Secondary endpoints were UDysRS and axial symptoms scores during the challenge; AIMS, UDysRS, and time spent with or without dyskinesia the day before the challenge. The primary analysis was performed in the per protocol population.

RESULTS

Sixteen patients were included in the analysis. There was no difference between naftazone and placebo for the AUC of MDS-UPDRS III (-89, 95%CI[-1071; 893], p = 0.85), and AIMS (70, 95%CI[-192; 332], p = 0.57). At the end of treatment periods, AIMS score tended to be lower with naftazone than placebo (4.4 ± 3.4 versus 6.7 ± 4.4, p = 0.07), but UDysRS scores and other secondary outcomes were not different. Naftazone was safe and well tolerated.

CONCLUSIONS

This study did not confirm previous results on the efficacy of naftazone on dyskinesia nor motor fluctuations highlighting the problem of translating results obtained in preclinical models into clinical trials. Further investigation of naftazone may be conducted in PD with longer treatment duration.

Synthesis and Antitumor Characterization of Pyrazolic Analogues of the Marine Pyrroloquinoline Alkaloids: Wakayin and Tsitsikammamines

A series of aza analogues of the marine alkaloids wakayin and tsitsikammamines A and B have been synthesized. The strategy used was based on [3 + 2] cycloaddition reactions involving 3-ethylamine-indole-4,7-dione and different diazo reagents. All the compounds were evaluated in vitro for antiproliferative activity against five distinct cancer cell lines and for their inhibitory effect on topoisomerase isoenzymes I and II. Some of the compounds inhibited the topoisomerase I and/or II catalyzed relaxation of supercoiled DNA at a concentration comparable to the drugs camptothecin and etoposide. Only a few of them exhibited cytotoxic activity with IC50 values in the micromolar range.

An hypothesis for the interpretation of the contractile response of vascular smooth muscle at the cellular level

The long preservation and recovery of functional (contractile) properties in cultured aortic smooth muscle cells, even after replating or deep-frozen storage and the measurement of their responses are now technically settled issues. We could thus study extensively the responses of single cultured cells from rat thoracic aorta. Responses were elicited by the addition of KCl 40 mmol/L without or with a calcium blocker PN 200-100 (10(-6) mol/L); angiotensin II (10(-11)-10(-6) mol/L) without or with antagonist (losartan 10(-5) mol/L); or serotonin (10(-9)-10(-4) mol/L) without or with antagonist (naftidrofuryl 10(-5) mol/L). Results thus obtained enabled us to propose a new hypothesis for the interpretation of the contractile responses of an elastic vascular smooth muscle. The different maximal effects of different agonists result mainly from the different proportions of cells they can mobilize; the agonist concentration-contraction relationship is mainly due to the increase of the proportion of cells involved up to a maximal value typical of the agonist used. An antagonist primarily reduce the proportion of cells an agonist can mobilize. Some of the consequences of this hypothesis are briefly outlined.

Use of a renal tubule cell line (LLC-PK1) to study the nephrotoxic potential of a kappa-type Bence-Jones protein

The cytotoxicity of a Bence-Jones protein was assessed using a porcine renal tubule cell line (LLC-PK1), with the aim of developing a model for studying the potential nephrotoxicity of these proteins. The effects of a kappa Bence-Jones protein on cell viability were studied by means of biochemical methods (supravital dye uptake and measurement of cellular enzyme activities) and morphological electron microscopy. After a 24-h-treatment with Bence-Jones protein, a moderate cytotoxicity (about 15%) was noted but only a minor difference compared to treatment with bovine albumin in the same conditions. The morphological study showed a few cells in the process of lysis, but their numbers were insufficient for the demonstration of a clear cytotoxic effect. Immunocytochemical studies showed Bence-Jones protein fixation on some cells, especially on the outer membrane. Labeling of the hyaloplasm and basal pole of a few cells pointed to internalization of protein by LLC-PK1 cells. Although the cytotoxicity of the Bence-Jones protein tested here was only moderate, the use of this model enabled its cytotoxic effect to be distinguished from that of beta-lactoglobulin. This isolate could serve as a "moderate control" for a later study with a BJP having caused acute renal failure.

Mitochondrial biogenesis in rabbit articular chondrocytes transferred to culture

The effect of the switch to aerobic growth conditions was examined in rabbit articular chondrocytes transferred to culture. Spectroscopic analysis of the cytochromes of the respiratory chain shows that only cytochrome b is present in chondrocytes from cartilage, cytochromes c, c1, and a.a3 being undetectable as compared with the typical spectrum found in a primary cell culture on day 4. Steady state levels of RNA transcripts of nuclear (cytochrome c) and mitochondrial genes (cytochrome b and cytochrome oxidase subunits II and III) involved in the oxidative metabolism were determined relative to the RNA transcripts of the nuclear gene for glyceraldehyde phosphate dehydrogenase involved in the glycolytic pathway and to mitochondrial ribosomal RNAs. Chondrocytes transferred to culture showed a general increase in the levels of all transcripts, but the effect on mitochondrial transcripts was much greater (x 20) than the effect on nuclear transcripts (x 3-4). These results show the absence of a coordinate regulation of the expression of mitochondrial and nuclear genes coding for components of the respiratory chain. The increase in mitochondrial DNA triggered by culture conditions does not appear to be sufficient to account for the enhanced transcription. Concomitant with these mitochondrial changes, the level of transcripts for the collagen II gene involved in the differentiation function decreases dramatically (3% of the control on day 3).

Rhodamine 123 uptake and mitochondrial DNA content in rabbit articular chondrocytes evolve differently upon transfer from cartilage to culture conditions

Mitochondrial DNA (mtDNA) represents 0.15% of the total cell DNA (at least an order of magnitude less than in liver or heart) of rabbit articular chondrocytes. Besides the already well-documented low respiratory activity, chondrocyte differentiation thus involves a specific control of mitochondrial biogenesis. When transferred to in vitro conditions, chondrocytes increase their stock of mtDNA at the same time they resume growth, even more efficiently (8 times) than they do for cell volume (4.4 times). On the contrary, overall mitochondrial activity, estimated as the uptake of rhodamine 123, does not follow the same trend (2.5 times increase). Chondrocytes apparently keep these functional characteristics for some generations in culture.

Mitochondrial uptake of rhodamine 123 by rabbit articular chondrocytes

Rhodamine 123 was used to stain and analyze by flow cytometry the mitochondria of rabbit articular chondrocytes. Stationary primary cultures and exponentially growing subcultures were compared to enzymatically released chondrocytes from cartilage. The increase in mitochondrial fluorescence, when chondrocytes are transferred from cartilage to culture environment, is suggestive of some change in chondrocyte adaptation and/or differentiation in these conditions.

Mitochondrial analysis in living cells: the use of rhodamine 123 and flow cytometry

Flow cytometry combines the advantages of microscopy and biochemical analysis in a single highly sensitive technique for a rapid examination of numerous individual living cells. It has become a potent and essential tool in the studies of the physiology of the whole cell and its organelles. Rhodamine 123 is a vital fluorescent dye used in flow cytometry. As it is specifically concentrated in mitochondria because of the transmembrane potential that these organelles maintain in living cells, rhodamine 123 is thus a useful probe for monitoring the abundance and activity of mitochondria. A critical survey of the routine use of rhodamine 123 together with flow cytometry in mitochondrial research is presented.