Key elements of preparedness for pandemic coronavirus disease 2019 (COVID-19) in nuclear medicine units

European Journal of Nuclear Medicine and Molecular Imaging -     

A new mutation in GJC2 associated with subclinical leukodystrophy

Recessive mutations in GJC2, the gene-encoding connexin 47 (Cx47), cause Pelizaeus–Merzbacher-like disease type 1, a severe dysmyelinating disorder. One recessive mutation (p.Ile33Met) has been associated with a much milder phenotype––hereditary spastic paraplegia type 44. Here, we present evidence that a novel Arg98Leu mutation causes an even milder phenotype––a subclinical leukodystrophy. The Arg98Leu mutant forms gap junction plaques in HeLa cells comparable to wild-type Cx47, but electrical coupling was 20-fold lower in cell pairs expressing Arg98Leu than for cell pairs expressing wild-type Cx47. On the other hand, coupling between Cx47Arg98Leu and Cx43WT expressing cells did not show such reductions. Single channel conductance and normalized steady-state junctional conductance–junctional voltage (G _j–V _j) relations differed only slightly from those for wild-type Cx47. Our data suggest that the minimal phenotype in this patient results from a reduced efficiency of opening of Cx47 channels between oligodendrocyte and oligodendrocyte with preserved coupling between oligodendrocyte and astrocyte, and support a partial loss of function model for the mild Cx47 associated disease phenotypes.     

Docetaxel and oxaliplatin combination in second-line treatment of patients with advanced gastric cancer

Background In advanced gastric cancer few data are available on the efficacy or safety of new drug combination regimens after progression following first-line chemotherapy. Methods Patients with histologically confirmed advanced gastric cancer and Eastern Cooperative Oncology Group (ECOG) performance status (PS) less than 2, progressing after first-line chemotherapy, were eligible. Patients were treated with docetaxel 75 mg/m² on day 1 and oxaliplatin 80 mg/m² on day 2, every 3 weeks, until progression or unacceptable toxicity. Results Between May 2002 and April 2005, 38 patients were enrolled. Men accounted for 73.7% of the patients and the median age was 59 years. The primary tumor was not resected in 47.4% of the patients; the peritoneum was the most frequent metastatic site (60.5%). The first-line treatment was cisplatin, epirubicin, and infusional 5-fluorouracil (ECF) in 81.5% of the patients and cisplatin and infusional 5-fluorouracil (CF) in 15.7%. The median number of cycles was 4.3. The treatment was well tolerated, with no toxic deaths. National Cancer Institute (NCI) grade III-IV neutropenia was frequent (26.3%), but no febrile neutropenia was reported. Severe asthenia (15.7%) and severe nausea (15.7%) required dose reductions in 2 patients and treatment discontinuation in another. The overall response rate was 10.5%, and 18 patients (47.3%) experienced disease stabilization (7 of them with significant clinical benefit). Median time to progression was 4.0 months (range, 2–8 months) and median overall survival was 8.1 months (range, 3–26 months). Thirteen patients (34.2%) also received third-line chemotherapy, with an irinotecan-containing regimen, and their median overall survival was higher than that of the other patients (16.3 vs 6.0 months) Conclusion The combination of oxaliplatin and docetaxel shows only marginal activity as second-line treatment, but it has a good tolerability profile. This suggests that there is room for optimizing the schedule as well as for planning sequential treatments in gastric cancer.     

Augmented acquisition of cocaine self-administration and altered brain glucose metabolism in adult female but not male rats exposed to a cannabinoid agonist during adolescence.

Marijuana consumption during adolescence has been proposed to be a stepping-stone for adult cocaine addiction. However, experimental evidence for this hypothesis is missing. In this work we chronically injected male and female Wistar rats with either the cannabinoid agonist CP 55,940 (CP; 0.4 mg/kg) or its corresponding vehicle. Adult acquisition (seven 30 min daily sessions) and maintenance (fourteen 2 h daily sessions) of cocaine self-administration (1 mg/kg), food-reinforced operant learning under conditions of normal (ad libitum access to food), and high motivation (food-restriction schedule) were measured. Additionally, brain metabolic activity was analyzed by means of [(18)F]-fluorodeoxyglucose positron emission tomography. During the acquisition phase, female CP-treated rats showed a higher rate of cocaine self-administration as compared to vehicle-treated females and males; no differences were found between both male groups. This effect disappeared in the maintenance phase. Moreover, no differences among groups were evident in the food-reinforced operant task, pointing to the cocaine-specific nature of the effect seen in self-administration rather than a general change in reward processing. Basal brain metabolic activity also changed in CP-treated females when compared to their vehicle-treated counterparts with no differences being found in the males; more specifically we observed a hyper activation of the frontal cortex and a hypo activation of the amygdalo-entorhinal cortex. Our results suggest that a chronic exposure to cannabinoids during adolescence alters the susceptibility to acquire cocaine self-administration, in a sex-specific fashion. This increased susceptibility could be related to the changes in brain metabolic activity induced by cannabinoids during adolescence.     

Chronic antidepressants induce redistribution and differential activation of alphaCaM kinase II between presynaptic compartments.

Changes in synaptic plasticity are involved in pathophysiology of depression and in the mechanism of antidepressants. Ca(2+)/calmodulin (CaM) kinase II, a protein kinase involved in synaptic plasticity, has been previously shown to be a target of antidepressants. We previously found that antidepressants activate the kinase in hippocampal neuronal cell bodies by increasing phosphorylation at Thr(286), reduce the kinase phosphorylation in synaptic membranes, and in turn its phosphorylation-dependent interaction with syntaxin-1 and the release of glutamate from hippocampal synaptosomes. Here, we investigated the chronic effect of different antidepressants (fluoxetine, desipramine, and reboxetine) on the expression and function of the kinase in distinct subcellular compartments in order to dissect the different kinase pools affected. Acute treatments did not induce any change in the kinase. In total tissue extracts chronic drug treatments induced activation of the kinase; in hippocampus (HC), but not in prefrontal/frontal cortex, this was partially accounted for by increased Thr(286) phosphorylation, suggesting the involvement of different mechanisms of activation. In synaptosomes, all drugs reduced the kinase phosphorylation, particularly in HC where, upon fractionation of the synaptosomal particulate into synaptic vesicles and membranes, we found that the drugs induced a redistribution and differential activation of the kinase between membranes and vesicles. Furthermore, a large decrease in the level and phosphorylation of synapsin I located at synaptic membranes was consistent with the observed decrease of CaM kinase II. Overall, antidepressants induce a complex pattern of modifications in distinct subcellular compartments; at presynaptic level, these changes are in line with a dampening of glutamate release.