Efficacy and safety of medical cannabinoids in older subjects: a systematic review

This systematic review aims to integrate the evidence on indications, efficacy, safety and pharmacokinetics of medical cannabinoids in older subjects. The literature search was conducted using PubMed, EMBASE, CINAHL and Cochrane Library. We selected controlled trials including solely older subjects (≥65 years) or reporting data on older subgroups. 105 (74%) papers, on controlled intervention trials, reported the inclusion of older subjects. Five studies reported data on older persons separately. These were randomized controlled trials, including in total 267 participants (mean age 47-78 years). Interventions were oral tetrahydrocannabinol (THC) (n=3) and oral THC combined with cannabidiol (n=2). The studies showed no efficacy on dyskinesia, breathlessness and chemotherapy induced nausea and vomiting. Two studies showed that THC might be useful in treatment of anorexia and behavioral symptoms in dementia. Adverse events were more common during cannabinoid treatment compared to the control treatment, and were most frequently sedation like symptoms. Although trials studying medical cannabinoids included older subjects, there is a lack of evidence of its use specifically in older patients. Adequately powered trials are needed to assess the efficacy and safety of cannabinoids in older subjects, as the potential symptomatic benefit is especially attractive in this age group.

Source levels and harmonic content of whistles in white-beaked dolphins (Lagenorhynchus albirostris)

Recordings of white-beaked dolphin whistles were made in Faxafl6i Bay (Iceland) using a three-hydrophone towed linear array. Signals from the hydrophones were routed through an amplifier to a lunch box computer on board the boat and digitized using a sample rate of 125 kHz per channel. Using this method more than 5000 whistles were recorded. All recordings were made in sea states 0-1 (Beaufort scale). Dolphins were located in a 2D horizontal plane by using the difference of arrival time to the three hydrophones, and source levels were estimated from these positions using two different methods (I and II). Forty-three whistles gave a reliable location for the vocalizing dolphin when using method II and of these 12 when using method I. Source level estimates on the center hydrophone were higher using method I [average source level 148 (rms) +/- 12 dB, n = 36] than for method II [average source level 139 (rms) +/- 12 dB, n = 36]. Using these rms values the maximum possible communication range for whistling dolphins given the local ambient noise conditions was then estimated. The maximum range was 10.5 km for a dolphin whistle with the highest source level (167 dB) and about 140 m for a whistle with the lowest source level (118 dB). Only two of the 43 whistles contained an unequal number of harmonics recorded at the three hydrophones judging from the spectrograms. Such signals could be used to calculate the directionality of whistles, but more recordings are necessary to describe the directionality of white-beaked dolphin whistles.

Structural and mechanistic insights into the interaction between Rho and mammalian Dia

Formins are involved in a variety of cellular processes that require the remodelling of the cytoskeleton. They contain formin homology domains FH1 and FH2, which initiate actin assembly. The Diaphanous-related formins form a subgroup that is characterized by an amino-terminal Rho GTPase-binding domain (GBD) and an FH3 domain, which bind somehow to the carboxy-terminal Diaphanous autoregulatory domain (DAD) to keep the protein in an inactive conformation. Upon binding of activated Rho proteins, the DAD is released and the ability of the formin to nucleate and elongate unbranched actin filaments is induced. Here we present the crystal structure of RhoC in complex with the regulatory N terminus of mammalian Diaphanous 1 (mDia1) containing the GBD/FH3 region, an all-helical structure with armadillo repeats. Rho uses its 'switch' regions for interacting with two subdomains of GBD/FH3. We show that the FH3 domain of mDia1 forms a stable dimer and we also identify the DAD-binding site. Although binding of Rho and DAD on the N-terminal fragment of mDia1 are mutually exclusive, their binding sites are only partially overlapping. On the basis of our results, we propose a structural model for the regulation of mDia1 by Rho and DAD.

The prognostic value of extracellular matrix component concentrations in serum during treatment of adult respiratory distress syndrome with extracorporeal CO2 removal

The time-dependent concentrations of hyaluronan, aminoterminal propeptide of type III procollagen, and laminin were determined in sera of 16 patients with severe adult respiratory distress syndrome during treatment with an extracorporeal CO2 removal device. Patients were classified according to lung parameters as responders (n = 10) and non-responders (n = 6) to extracorporeal CO2 removal. At the beginning of treatment strongly elevated serum concentrations of all studied extracellular matrix components were found. During the first 6-11 days of treatment the concentrations of aminoterminal propeptide of type III procollagen and hyaluronan increased further in non-responders but decreased in the majority of responders, while laminin decreased in both groups. No significant correlations were found between the serum concentrations of connective tissue components and the parameters of lung function. By non-parametric analysis of variance, significant differences between responders and non-responders according to treatment time could be established. By analysing the time course of the serum concentrations of hyaluronan and aminoterminal propeptide of type III procollagen, a total differentiation between responders and nonresponders was made possible by the trends of these analytes as early as three days after the start of treatment. The determination of aminoterminal propeptide of type III procollagen and hyaluronan in serum of patients with adult respiratory distress syndrome might therefore have prognostic significance in extracorporeal CO2 removal.

Immunonephelometric quantification of free haemoglobin

A fully mechanized immunonephelometric method for rapid and specific determination of free haemoglobin in serum, plasma, or aqueous haemolysates is described. It utilizes commercially available rabbit antiserum against human haemoglobin and the Behring Nephelometer Analyser. A single determination is performed within 6 minutes and requires 250 microliters total sample volume. The measuring range is about 9-2300 mg/ml haemoglobin. Precision is characterized by intraassay coefficients of variation of 3.4% and 1.6%, and interassay coefficients of variation of 8.2% and 5.6% for haemoglobin concentrations of 29 mg/l and 119 mg/l, respectively. Accuracy of the method is shown by close correlation to haemoglobin determination by cyanohaemiglobin spectrometry (r = 0.9837). Interference may occur for visibly lipaemic samples. A preliminary comparison of different specimens drawn in parallel shows lowest haemoglobin concentrations in citrate plasma, followed by heparin plasma and by serum, while EDTA-plasma is unsuitable for this analysis.

Binding of chondroitin sulfate, dermatan sulfate and fat-storing cell-derived proteoglycans to rat hepatocytes

1. The interaction of isolated rat hepatocytes with exogenous 3H-labeled chondroitin-4-sulfate and dermatan sulfate and with biosynthetically 35S-labeled proteoglycans secreted by cultured rat liver fat-storing cells has been studied. 2. All ligands are bound by hepatocytes in a concentration-dependent manner. Scatchard-plot analysis of the data revealed the existence of high- and low-affinity binding modes. 3. The cell-bound exogenous [3H]glycosaminoglycans could be displaced by each unlabeled ligand and by heparin, whereas displacement of the endogenous material was less effective. 4. Binding of all ligands to hepatocytes increased with time. For the exogenous glycosaminoglycans the two- to threefold amount was retained at 37 degrees C as compared to 4 degrees C; it was markedly reduced by pretreatment of the cells with trypsin. 5. Degradation of the exogenous ligands could be detected neither for the cell-bound fraction nor for the free glycosaminoglycans in the culture medium. 6. The binding of the ligands to hepatocytes is viewed as a cell-matrix interaction. Its possible pathobiochemical relevance in liver fibrosis or neoplasia is discussed.

Deoxyribonucleotide biosynthesis in yeast: assay and properties of ribonucleotide reductase in permeabilized Saccharomyces cerevisiae cells

Yeast cells permeabilized by freeze-thaw cycles in a sorbitol-containing medium provide an experimentally favorable system for the study of ribonucleotide reduction in a small number of cells or in mutant strains. Ribonucleotide reductase activities determined in such cells are about twice those found in cell extracts but properties of the enzyme, except pH optimum, are closely comparable in both assay procedures. In contrast with other organisms, the activities measured in permeabilized cells from both diploid or haploid strains exceed the demand for deoxyribonucleotide formation during replication of the yeast genome. The method has been applied to yeast cultures growing in the presence of the ribonucleotide reductase inhibitor hydroxyurea and a twofold increase of enzyme activity has been established in such cells. On the other hand, analysis of a series of hus mutants, selected for hydroxyurea sensitivity in the laboratory of Singer and Johnston did not reveal obvious alterations of the enzyme vs the parental strains, suggesting that the hus phenotype may be due to lesions other than in ribonucleotide reductase.

Deoxyribonucleotide biosynthesis in yeast (Saccharomyces cerevisiae). A ribonucleotide reductase system of sufficient activity for DNA synthesis

Ribonucleotide reductase, the central enzyme of DNA precursor biosynthesis, has been isolated and characterized from baker's yeast. The enzyme activity, measured in extracts from three different, exponentially growing yeast strains, is high enough to meet the substrate requirement of DNA replication, in contrast to very low activities found in most other organisms. In thymidylate-permeable yeast cells ribonucleotide reductase activity is stimulated under both starvation and excess of intracellular dTMP. On the other hand growth of yeast in presence of 20 mM hydroxyurea did not increase enzyme activity. Yeast ribonucleotide reductase is composed of two non-identical subunits, inactive separately, of which one binds to immobilized dATP. The relative molecular mass of the holoenzyme is about 250 000. The enzyme reduces all four natural ribonucleoside diphosphates with comparable efficacy. GDP reduction requires dTTP as effector, ADP reduction is stimulated by dGTP, whereas pyrimidine nucleotide reduction is stimulated by any deoxyribonucleotide and ATP. Enzyme activity is independent of exogenous metal ions and is insensitive towards chelating agents. Hydroxyurea inactivates yeast ribonucleotide reductase in a slow reaction; half-inhibition (I50) is reached only at 2-6 mM hydroxyurea concentration. Up to 50% reactivation occurs spontaneously after removal of the inhibitor. In accord with previous attempts by others, extensive purification of the yeast enzyme has failed owing to its extreme instability in solution; the half-life of about 11 h could not be influenced by any protective measure. Taken together, yeast ribonucleotide reductase combines features known from Escherichia coli and mammalian enzymes with differing, individual properties.

Aurintricarboxylic acid and polynucleotides as novel inhibitors of ribonucleotide reductases

Ribonucleoside diphosphate reductases isolated from Escherichia coli, baker's yeast, Ehrlich ascites tumor cells, and unicellular green alga (Scenedesmus obliquus) are inhibited strongly and uniformly by the polymeric triphenylmethane dye, aurintricarboxylic acid. The molecule appears to interact simultaneously with the enzyme's various nucleotide and catalytic (iron-organic radical) sites. Oligo- and polyribonucleotides are also inhibitory. These reactions serve as models of the probably physiologic regulation of ribonucleotide reduction exerted by natural inhibitors. Partial characterization of an inhibitor fraction found in wheat seed embryo is described.