Site and mechanism of behavioral tolerance to cocaine: A study of dopamine release in Wistar-Kyoto and spontaneously hypertensive rats

Wistar-Kyoto and spontaneously hypertensive rats received i.v. infusions of cocaine hydrochloride (60 mg/kg per day) for 3, 7, and 14 days, or saline for 7 days. Acute cocaine challenge (40 mg/kg, s.c.) was given to treated and control rats 24 hr after the termination of each infusion period. There were no strain differences in brain levels of cocaine during cocaine infusion, nor after cocaine challenges. There were no strain differences in resting levels of [³H]dopamine release. Release of [³H]dopamine decreased in nuclei accumbens of 7- and 14-day cocaine-infused animals. Release of [³H]dopamine was maximal in both brain regions 2 hr after acute cocaine challenge. After 14 days of cocaine infusion, cocaine challenge in both strains reduced [³H]dopamine release in the nucleus accumbens, but not in the striatum; the reduction being greater in Wistar-Kyoto rats. The behavioral tolerance which accompanies similar cocaine infusion regimens may be related to striatal tolerance to cocaine-induced dopamine release.     

The int genes of bacteriophages P22 and λ are regulated by different mechanisms

Bacteriophage P22 and λ are related bacteriophages with similar gene organizations. In λ the cII-dependent P_I promoter is responsible for λint gene expression. The only apparent counterpart to P_I in P22 is oriented in the opposite direction, and cannot transcribe the P22 int gene. We show that this promoter, called P_al, is active both in vivo and in vitro, and is dependent upon the P22 cII-like gene, called c1. We have also determined the DNA sequence of a 3.3 kb segment that closes the gap between previously reported sequences to give a continuous sequence between the P22 p_L promoter and the int gene. The newly determined sequence is densely packed with genes from the p_L direction, and the proteins predicted by the sequence show excellent correlation with the proteins mapped by Youderian and Susskind in 1980. However, the sequence contains no apparent genes in the opposite (p_al) direction, and no additional binding motifs for the P22 c1 protein. We conclude that int gene expression in P22 is regulated by a different mechanism than in λ.     

Novel (E)-3-(3-Oxo-4-substituted-3,4-dihydro-2H-benzo[b][1,4]oxazin-6-yl)-N-hydroxypropenamides as Histone Deacetylase Inhibitors: Design,Synthesis and Bioevaluation

Herein, we report the design, synthesis and evaluation of novel (E)-3-(3-oxo-4-substituted-3,4-dihydro-2H-benzo[b][1,4]oxazin-6-yl)-N-hydroxypropenamides ( 4 a – i , 7 a – g ) targeting histone deacetylases. Three human cancer cell lines were used to test the cytotoxicity of the synthesized compounds (SW620, colon; PC-3, prostate; NCI−H23, lung cancer); inhibitory activity towards HDAC; anticancer activity; as well as their impact on the cell cycle and apoptosis. As a result, compounds 4 a – i bearing the alkyl substituents seemed to be less potent than the benzyl-containing compounds 7 a – g in all biological assays. Compounds 7 e – f were found to be the most active HDAC inhibitors with IC₅₀ of 1.498±0.020 μM and 1.794±0.159 μM, respectively. In terms of cytotoxicity and anticancer assay, 7 e and 7 f also showed good activity with IC₅₀ values in the micromolar range. In addition, the cell cycle and apoptosis of SW620 were affected by compound 7 f in almost a similar manner to that of reference compound SAHA. Docking assays were carried out for analysis the binding mode and selectivity of this compound toward 8 HDAC isoforms. Overall, our data confirmed that the inhibition of HDAC plays a pivotal role in their anticancer activity.     

Treatment-resistant depression: definition,prevalence, detection,management, and investigational interventions

Treatment-resistant depression (TRD) is common and associated with multiple serious public health implications. A consensus definition of TRD with demonstrated predictive utility in terms of clinical decision-making and health outcomes does not currently exist. Instead, a plethora of definitions have been proposed, which vary significantly in their conceptual framework. The absence of a consensus definition hampers precise estimates of the prevalence of TRD, and also belies efforts to identify risk factors, prevention opportunities, and effective interventions. In addition, it results in heterogeneity in clinical practice decision-making, adversely affecting quality of care. The US Food and Drug Administration (FDA) and the European Medicines Agency (EMA) have adopted the most used definition of TRD (i.e., inadequate response to a minimum of two antidepressants despite adequacy of the treatment trial and adherence to treatment). It is currently estimated that at least 30% of persons with depression meet this definition. A significant percentage of persons with TRD are actually pseudo-resistant (e.g., due to inadequacy of treatment trials or non-adherence to treatment). Although multiple sociodemographic, clinical, treatment and contextual factors are known to negatively moderate response in persons with depression, very few factors are regarded as predictive of non-response across multiple modalities of treatment. Intravenous ketamine and intranasal esketamine (co-administered with an antidepressant) are established as efficacious in the management of TRD. Some second-generation antipsychotics (e.g., aripiprazole, brexpiprazole, cariprazine, quetiapine XR) are proven effective as adjunctive treatments to antidepressants in partial responders, but only the olanzapine-fluoxetine combination has been studied in FDA-defined TRD. Repetitive transcranial magnetic stimulation (TMS) is established as effective and FDA-approved for individuals with TRD, with accelerated theta-burst TMS also recently showing efficacy. Electroconvulsive therapy is regarded as an effective acute and maintenance intervention in TRD, with preliminary evidence suggesting non-inferiority to acute intravenous ketamine. Evidence for extending antidepressant trial, medication switching and combining antidepressants is mixed. Manual-based psychotherapies are not established as efficacious on their own in TRD, but offer significant symptomatic relief when added to conventional antidepressants. Digital therapeutics are under study and represent a potential future clinical vista in this population.     

Heat shock in mechanically wounded carrot root disks causes destabilization of stable secretory protein mRNA and dissociation of endoplasmic reticulum lamellae

In many organisms, the synthesis of heat shock proteins during heat shock is concomitant with the cessation of at least a portion of normal cellular protein synthesis. Heat shocked barley aleurone layers selectively stop the synthesis and secretion of secretory proteins. Exposure to 40°C causes a disruption of endoplasmic reticulum (ER) lamellae, which we have hypothesized leads to the destabilization of otherwise stable mRNA previously associated with ER‐bound polyribosomes. We report here that this was also observed in wounded carrot ( Daucus carota L.) root parenchyma tissue which synthesizes and secretes cell wall proteins when mechanically wounded. Nondenaturing cationic polyacrylamide gel electrophoresis of radiolabeled proteins indicated that heat shock caused the cessation of the synthesis and secretion of extensin, a hydroxyproline‐rich cell wall glycoprotein. Northern blot analyses indicated that the mRNA levels for both extensin and another cell wall protein (p33) were rapidly diminished during heat shock. Under nonheat shock conditions extensin mRNA had a half‐life of greater than 4 h, but this appeared to be reduced to less than 30 min during heat shock. There was also a concomitant dissociation of ER lamellae in wounded, heat shocked carrot root tissue, as observed by transmission electron microscopy. These observations indicate that this response may be universal among plant secretory tissues.     

Internal pH crisis, lysine decarboxylase and the acid tolerance response of Salmonella typhimurium

Salmonella typhimurium possesses an adaptive response to acid that increases survival during exposure to extremely low pH values. The acid tolerance response (ATR) includes both log-phase and stationary-phase systems. The log-phase ATR appears to require two components for maximum acid tolerance, namely an inducible pH homeostasis system, and a series of acid-shock proteins. We have discovered one of what appears to be a series of inducible exigency pH homeostasis systems that contribute to acid tolerance in extreme acid environments. The low pH-inducible lysine decarboxylase was shown to contribute significantly to pH homeostasis in environments as low as pH 3.0. Under the conditions tested, both lysine decarboxylase and σ^s-dependent acid-shock proteins were required for acid tolerance but only lysine decarboxylase contributed to pH homeostasis. The cadBA operon encoding lysine decarboxylase and a lysine/cadaverine antiporter were cloned from S. typhimurium and were found to be 79% homologous to the cadBA operon from Escherichia coli . The results suggest that S. typhimurium has a variety of means of fulfilling the pH homeostasis requirement of the ATR in the form of inducible amino acid decarboxylases.     

Translatable RNA Populations Associated with Maintenance of Primary Root Elongation and Inhibition of Mesocotyl Elongation by Abscisic Acid in Maize Seedlings at Low Water Potentials

Previous work indicated that accumulation of abscisic acid (ABA) acts differentially to maintain elongation of the primary root and inhibit elongation of the mesocotyl of maize (Zea mays L.) seedlings at low water potentials ([psi]w). Subsequent results indicated specific locations in the elongation zones where elongation is maintained, inhibited, or unaffected by endogenous ABA at low [psi]w. This information was utilized in this study to identify in vitro translation products of RNA associated with the maintenance or inhibition of elongation in the primary root and mesocotyl, respectively, by endogenous ABA at low [psi]w. The results distinguished products associated specifically with the elongation responses from those nonspecifically associated with ABA accumulation or low [psi]w, as well as normal cell development and maturation. In the primary root, the maintenance of elongation at low [psi]w by ABA was associated with the maintenance of expression of three products that were also expressed during elongation at high [psi]w, the expression of a novel product, and the suppression of two products. In the mesocotyl, the inhibition of elongation by ABA after transplanting to low [psi]w was associated with the induction of a novel translation product. However, the induction of this product, as well as accumulation of ABA and inhibition of elongation, occurred without a decline in tissue water content. The results demonstrate the necessity of examining the association of gene expression with elongation responses to low [psi]w with a high degree of spatial resolution.     

Effect of different donor cells on human immunodeficiency virus type 1 replication and selection in vitro.

We sought to determine the effects of different host cells on human immunodeficiency virus type 1 (HIV-1) infection in vitro. First, 17 primary viruses of various phenotypes were examined for replicative capacity in peripheral blood mononuclear cells (PBMC) from 10 healthy donors. While the range of infection was variable over a 40-fold range, it was substantially less than that previously reported (L. M. Williams and M. W. Cloyd, Virology 184:723-728, 1991). In particular, no donor cells demonstrated total resistance to HIV-1 infection. We next cocultured PBMC from an HIV-1-infected patient with stimulated PBMC from three healthy donors to determine the effect of host cells on selection for a particular HIV-1 quasispecies. By using DNA sequencing, it was found that the dominant quasispecies (AD30-15) after culture was nearly identical in the cells of different donors. Furthermore, after 6 months in vivo, the patient developed a dominant proviral population in PBMC that was most closely related to the quasispecies preferentially selected in vitro, although this quasispecies was only a minor fraction of the sequences present earlier in PBMC. In subsequent biological characterizations, it was found that AD30-15 grew much better in PBMC and macrophages than did other related quasispecies. Hence, we conclude that the primary mechanism of in vitro selection for a particular HIV-1 variant in this case is mediated by the phenotypic properties of the virus and is less dependent on host cell origin. The findings reported here have important practical implications for studies of HIV-1 replication in primary cells derived from healthy donors.