Metallothionein protection of cadmium toxicity

The discovery of the cadmium (Cd)-binding protein from horse kidney in 1957 marked the birth of research on this low-molecular weight, cysteine-rich protein called metallothionein (MT) in Cd toxicology. MT plays minimal roles in the gastrointestinal absorption of Cd, but MT plays important roles in Cd retention in tissues and dramatically decreases biliary excretion of Cd. Cd-bound to MT is responsible for Cd accumulation in tissues and the long biological half-life of Cd in the body. Induction of MT protects against acute Cd-induced lethality, as well as acute toxicity to the liver and lung. Intracellular MT also plays important roles in ameliorating Cd toxicity following prolonged exposures, particularly chronic Cd-induced nephrotoxicity, osteotoxicity, and toxicity to the lung, liver, and immune system. There is an association between human and rodent Cd exposure and prostate cancers, especially in the portions where MT is poorly expressed. MT expression in Cd-induced tumors varies depending on the type and the stage of tumor development. For instance, high levels of MT are detected in Cd-induced sarcomas at the injection site, whereas the sarcoma metastases are devoid of MT. The use of MT-transgenic and MT-null mice has greatly helped define the role of MT in Cd toxicology, with the MT-null mice being hypersensitive and MT-transgenic mice resistant to Cd toxicity. Thus, MT is critical for protecting human health from Cd toxicity. There are large individual variations in MT expression, which might in turn predispose some people to Cd toxicity.     

Superstitious conditioning as a model of delusion formation following chronic but not acute ketamine in humans

Background

Ketamine has previously been shown to induce delusion-like or referential beliefs, both acutely in healthy volunteers and naturalistically among nonintoxicated users of the drug. Delusions are theoretically underpinned by increased superstitious conditioning or the erroneous reinforcement of random events.

Materials and methods

Using a novel and objectively measured superstitious conditioning task, experiment 1 assessed healthy volunteers before and during placebo (n?=?16), low-dose (n?=?15), and high-dose ketamine (n?=?16) under randomized and double-blind conditions. Experiment 2 used the same task to compare ketamine users (n?=?18), polydrug controls (n?=?19), and nondrug-using controls (n?=?17).

Results

In experiment 1, ketamine produced dose-dependent psychotomimetic effects but did not cause changes in superstitious conditioning. Experiment 2 found increased levels of superstitious conditioning among ketamine users compared to polydrug and nondrug-using controls, respectively, as evidenced by both objective task responses and subjective beliefs following the task.

Conclusions

Results indicate that chronic but not acute exposure to ketamine may increase the propensity to adopt superstitious conditioning. These findings are discussed in terms of acute and chronic ketamine models of delusion-like belief formation in schizophrenia.     

Effect of menstrual cycle phase on dopamine D2 receptor availability in female cynomolgus monkeys

Sex differences have been reported in a variety of affective and neurodegenerative disorders that involve dysfunctional dopamine (DA) neurotransmission. In addition, there is evidence for differences in sensitivity to the abuse-related effects of psychostimulants across the menstrual cycle which may result from effects of ovarian hormones on DA function. The goal of the present study was to extend previous work examining menstrual cycle-related changes in DA D2 receptor availability in humans to drug-naive female cynomolgus monkeys (n=7) using the selective D2-like receptor ligand [(18)F]fluoroclebopride (FCP) and a high-resolution microPET P4 scanner. Menstrual cycle phase was characterized by daily vaginal swabs and measurements of serum progesterone levels. PET studies were conducted once during the luteal phase and once during the follicular phase. Regions of interest in the caudate nucleus, putamen, and cerebellum were defined on coregistered MRIs. Distribution volumes were calculated for FCP in each structure and the distribution volume ratio (DVR) for both brain regions relative to the cerebellum was used as a measure of D2 receptor availability. FCP DVRs were significantly higher in the luteal phase compared to the follicular phase in both the caudate nucleus (11.7% difference, p=0.02) and putamen (11.6% difference, p=0.03). These findings extend earlier work in humans and suggest that changes in DA receptor availability may be involved in the variation in symptoms of various neuropsychiatric disorders across the menstrual cycle, including differences in sensitivity to the abuse-related effects of stimulants.     

Severe prosthetic joint infection in an immunocompetent male patient due to a therapy refractory Pseudallescheria apiosperma

Prosthetic joint infections (PJI) are rarely due to fungal agents and if so they are mainly caused by Candida strains. This case represents a PJI caused by a multi-drug resistant Pseudallescheria apiosperma, with poor in vivo response to itraconazole and voriconazole. This case differs also by the way of infection, since the joint infection did not follow a penetrating trauma. In the majority of cases, Scedosporium extremity infections remain local in immunocompetent individuals. We report a persistent joint infection with multiple therapeutic failures, and subsequent amputation of the left leg. Detailed clinical data, patient history, treatment regime and outcome of a very long-lasting (>4 years) P. apiosperma prosthetic knee infection in an immunocompetent, 61-year-old male patient are presented with this case. The patient was finally cured by the combination of multiple and extensive surgical interventions and prolonged antifungal combination therapy with voriconazole and terbinafine.     

Activation of cAMP-dependent signaling pathway induces mouse organic anion transporting polypeptide 2 expression

Rodent Oatp2 is a hepatic uptake transporter for such compounds as cardiac glycosides. In the present study, we found that fasting resulted in a 2-fold induction of Oatp2 expression in liver of mice. Because the cAMP-protein kinase A (PKA) signaling pathway is activated during fasting, the role of this pathway in Oatp2 induction during fasting was examined. In Hepa-1c1c7 cells, adenylyl cyclase activator forskolin as well as two cellular membrane-permeable cAMP analogs, dibutyryl cAMP and 8-bromo-cAMP, induced Oatp2 mRNA expression in a time- and dose-dependent manner. These three chemicals induced reporter gene activity in cells transfected with a luciferase reporter gene construct containing a 7.6-kilobase (kb) 5'-flanking region of mouse Oatp2. Transient transfection of cells with 5'-deletion constructs derived from the 7.6-kb Oatp2 promoter reporter gene construct, as well as 7.6-kb constructs in which a consensus cAMP response element (CRE) half-site CGTCA (-1808/-1804 bp) was mutated or deleted, confirms that this CRE site was required for the induction of luciferase activity by forskolin. Luciferase activity driven by the Oatp2 promoter containing this CRE site was induced in cells cotransfected with a plasmid encoding the protein kinase A catalytic subunit. Cotransfection of cells with a plasmid encoding the dominant-negative CRE binding protein (CREB) completely abolished the inducibility of the reporter gene activity by forskolin. In conclusion, induction of Oatp2 expression in liver of fasted mice may be caused by activation of the cAMP-dependent signaling pathway, with the CRE site (-1808/-1804) and CREB being the cis- and trans-acting factors mediating the induction, respectively.     

The Impact of Preconception Gastric Bypass Surgery on Maternal Micronutrient Status before and during Pregnancy: A Retrospective Cohort Study in the Netherlands between 2009 and 2019

Post-bariatric weight loss can cause iatrogenic malnutrition and micronutrient depletion. In this study, we evaluated the impact of gastric bypass surgery (GB) and multivitamin supplement use on maternal micronutrient status before and across pregnancy. A retrospective medical chart review of 197 singleton pregnancies after GB with a due date between 2009 and 2019 was performed at a bariatric expertise center in the Netherlands. Hemoglobin, calcium, iron status, folate, vitamin D, vitamin B12 and ferritin levels were determined before and after GB during standard follow-up and at all gestational trimesters and analyzed using linear mixed models. Patients were prescribed standard multivitamin supplements or multivitamins specifically developed for post-bariatric patients (FitForMe WLS Forte (FFM)). Overall, hemoglobin and calcium levels decreased after surgery and during pregnancy, whereas folate, vitamin D, and vitamin B12 levels increased, and iron levels remained stable. FFM use was associated with higher hemoglobin, folate, vitamin D, and ferritin levels. In conclusion, through adequate supplementation and follow-up, GB does not have to result in impaired micronutrient status. Supplements developed specifically for post-bariatric patients generally result in higher micronutrient values than regular multivitamins before and during pregnancy. These data emphasize the urgent need for nutritional counseling including dietary and multivitamin supplement advise for post-bariatric women contemplating and during pregnancy.     

In Vitro Antifungal Susceptibilities and Amplified Fragment Length Polymorphism Genotyping of a Worldwide Collection of 350 Clinical,Veterinary, and Environmental Cryptococcus gattii Isolates

The in vitro susceptibilities of a worldwide collection of 350 Cryptococcus gattii isolates to seven antifungal drugs, including the new triazole isavuconazole, were tested. With amplified fragment length polymorphism (AFLP) fingerprinting, human, veterinary, and environmental C. gattii isolates were subdivided into seven AFLP genotypes, including the interspecies hybrids AFLP8 and AFLP9. The majority of clinical isolates (n = 215) comprised genotypes AFLP4 (n = 76) and AFLP6 (n = 103). The clinical AFLP6 isolates had significantly higher geometric mean MICs for flucytosine and fluconazole than the clinical AFLP4 isolates. Of the seven antifungal compounds examined in this study, isavuconazole had the lowest MIC₉₀ (0.125 μg/ml) for all C. gattii isolates, followed by a 1 log₂ dilution step increase (MIC₉₀, 0.25 μg/ml) for itraconazole, voriconazole, and posaconazole. Amphotericin B had an acceptable MIC₉₀ of 0.5 μg/ml, but fluconazole and flucytosine had relatively high MIC₉₀s of 8 μg/ml.The basidiomycetous yeast Cryptococcus gattii is responsible for life-threatening invasive disease in apparently healthy humans and animals (7, 19). A typical C. gattii infection is acquired through the respiratory tract, from which it can further disseminate to the central nervous system, resulting in fatal meningitis (7, 19, 32). Cryptococcosis caused by the primary pathogenic yeast C. gattii was, until a decade ago, a rarely encountered infection outside tropical and subtropical regions (17, 26, 27). However, this changed due to an unprecedented outbreak that emerged in the temperate climate of Vancouver Island (British Columbia, Canada) that subsequently expanded farther into the Pacific Northwest (1, 8, 10, 16). Its sibling species, Cryptococcus neoformans, differs ecologically and epidemiologically from C. gattii since it occurs on a global scale and is linked with disease occurring in immunocompromised individuals, such as HIV-positive patients and transplant patients who receive immune-suppressive medicines (7, 10, 18, 19, 31).Cryptococcus gattii can be discerned from C. neoformans using a wide range of microbiological and molecular techniques (7, 20). A convenient method is the use of canavanine-glycine-bromothymol blue (CGB) medium, which allows C. gattii but not C. neoformans to grow and which changes the pH indicator in the medium from green-yellowish to blue (18). With the increasing use of molecular techniques, such as PCR fingerprinting, restriction fragment length polymorphism (RFLP) analysis of the PLB1 and URA5 loci, and amplified fragment length polymorphism (AFLP) fingerprint analysis, as well as several multilocus sequence typing (MLST) approaches, it became clear that C. gattii could be divided into five distinct genotypes, named AFLP4/VGI, AFLP5/VGIII, AFLP6/VGII, AFLP7/VGIV, and AFLP10 (the last one of which is a recently observed novel genotype) (2, 6, 7, 13, 16, 20, 21, 23). Until recently, a serotype agglutination assay was widely used to distinguish C. neoformans (serotypes A and D) from C. gattii (serotypes B and C) (7, 27). In general, serotype B strains are found in each of the five C. gattii AFLP genotypes, but it seems that C. gattii serotype C strains are restricted to genotypes AFLP5/VGIII and AFLP7/VGIV (2, 6, 16, 21, 27).In addition, it was found that C. gattii and C. neoformans can form interspecies hybrids, named genotype AFLP8 (C. neoformans var. neoformans AFLP2/VNIII serotype D × C. gattii AFLP4/VGI serotype B) and AFLP9 (C. neoformans var. grubii AFLP1/VNI serotype A × C. gattii AFLP4/VGI serotype B). These interspecies hybrids have, until now, been isolated only from clinical samples, and they might have a higher virulence potential than regular C. gattii or C. neoformans isolates (4, 5; F. Hagen, K. Tintelnot, and T. Boekhout, unpublished data).Treatment of cryptococcosis depends on, besides the immune status of the patient, the severity and localization of the infection (11). Severe cases of cryptococcosis in immunocompetent and -compromised patients are treated according to the guidelines of the Infectious Diseases Society of America, according to which treatment consists of an induction therapy for 2 weeks with a combination of amphotericin B and flucytosine, followed by a 10-week consolidation therapy with fluconazole (11, 24).Cryptococcus neoformans has been extensively studied for its in vitro susceptibility to a wide variety of antifungal compounds, including the new triazoles posaconazole, voriconazole, ravuconazole, and isavuconazole (12, 14, 28, 29, 33). Despite the ongoing C. gattii outbreak, only a few studies using relatively small sets of C. gattii isolates have been performed to investigate their in vitro susceptibilities to amphotericin B, flucytosine, fluconazole, and the new triazole antifungals (12, 15, 28-30). A few studies divided the C. gattii isolates into groups according to their serotype or genotype (15, 29).Therefore, we studied the in vitro susceptibilities of each of the C. gattii genotypes from a large worldwide collection, subdivided by AFLP genotyping, to amphotericin B, flucytosine, fluconazole, itraconazole, voriconazole, posaconazole, and the new experimental broad-spectrum antifungal triazole isavuconazole.