Acanthamoeba Encephalitis: Isolation of Genotype T1 in Mycobacterial Liquid Culture Medium

We report a case of Acanthamoeba encephalitis diagnosed from an antemortem brain biopsy specimen, where the organism was first isolated in mycobacterial liquid medium and first identified by using a sequence generated by a commercial panfungal sequencing assay. We correlate susceptibility results with clinical outcome.     

Resident-to-resident aggression in long-term care facilities: insights from focus groups of nursing home residents and staff

OBJECTIVES: To more fully characterize the spectrum of resident‐to‐resident aggression (RRA). DESIGN: A focus group study of nursing home staff members and residents who could reliably self‐report. SETTING: A large, urban, long‐term care facility. PARTICIPANTS: Seven residents and 96 staff members from multiple clinical and nonclinical occupational groups. MEASUREMENTS: Sixteen focus groups were conducted. Content was analyzed using nVivo 7 software for qualitative data. RESULTS: Thirty‐five different types of physical, verbal, and sexual RRA were described, with screaming or yelling being the most common. Calling out and making noise were the most frequent of 29 antecedents identified as instigating episodes of RRA. RRA was most frequent in dining and residents' rooms, and in the afternoon, although it occurred regularly throughout the facility at all times. Although no proven strategies exist to manage RRA, staff described 25 self‐initiated techniques to address the problem. CONCLUSION: RRA is a ubiquitous phenomenon in nursing home settings, with important consequences for affected individuals and facilities. Further epidemiological research is necessary to more fully describe the phenomenon and identify risk factors and preventative strategies.     

Inhibitory and stimulatory regulation of testicular inhibin B secretion by luteinizing hormone and follicle-stimulating hormone,respectively, in the rhesus monkey (Macaca mulatta)

This study examined the relative role of FSH and LH in governing testicular inhibin B secretion in the rhesus monkey. Adult male monkeys, rendered hypogonadotropic and hypogonadal by administration of a GnRH receptor antagonist (acyline), were implanted with testosterone (T)-filled or empty capsules. Following T-induced restoration of spermatogenesis, both groups received recombinant human FSH and vehicle for 12 d. Juvenile male monkeys received an 11-d infusion of single-chain recombinant human LH and recombinant human FSH, either alone or in combination. In adults, chronic hypogonadotropism resulted in a modest reduction of circulating inhibin B levels, which was more than fully reversed by FSH. In the presence of T, which exerted a marked suppression in inhibin B secretion, FSH restored inhibin B levels only to those observed before acyline treatment. In juveniles, treatment with single-chain recombinant human LH led to a suppression of inhibin B secretion and curtailed the FSH-induced stimulation of this testicular hormone. The T-induced decrease in inhibin B secretion was associated with suppression in inhibin-beta(B) mRNA levels, but FSH stimulation of inhibin B secretion occurred in the absence of clear changes in expression of this subunit gene. These findings indicate that inhibin B secretion by the monkey testis is governed by the inhibitory and stimulatory action of LH and FSH, respectively. The action of LH is presumably indirect and likely mediated by T inhibition of inhibin-beta(B) gene expression. The molecular basis of the stimulatory action of FSH on inhibin B secretion requires further study.     

Historical review on thymosin α1 in oncology: preclinical and clinical experiences

Introduction: Thymosin α1 (Tα1) is a naturally occurring polypeptide that regulates immune cell development and function, and is also capable of interacting with multiple target cells with relevant biological effects. The rationale of Tα1 use in cancer treatment stems from the consideration that tumor progression is favored by a failure of the immune response and in turn induces immune suppression. This paper will review the historical background of Tα1 use in oncology, aiming to highlight the importance of Tα1 as an immunotherapeutic tool to be used in combination with chemotherapy, a concept that is not yet fully established in clinic.

Areas covered: The efficacy and safety of combining Tα1 with chemotherapy and cytokines were first evaluated in murine tumor models, providing essential information about effects, mechanisms of action, doses and treatment protocols. The therapeutic potential of the chemo-immunotherapy protocol on metastatic melanoma and lung cancer has been confirmed in controlled clinical trials. Critical for the efficacy of the chemo-immunotherapy protocol is the dual action of Tα1 on immune effector and tumor cells.

Expert opinion: On the basis of the preclinical and clinical results available, the use of the chemo-immunotherapy protocol, in which the role of Tα1 is central, is strongly recommended.     

Purinosome formation as a function of the cell cycle

The de novo purine biosynthetic pathway relies on six enzymes to catalyze the conversion of phosphoribosylpyrophosphate to inosine 5′-monophosphate. Under purine-depleted conditions, these enzymes form a multienzyme complex known as the purinosome. Previous studies have revealed the spatial organization and importance of the purinosome within mammalian cancer cells. In this study, time-lapse fluorescence microscopy was used to investigate the cell cycle dependency on purinosome formation in two cell models. Results in HeLa cells under purine-depleted conditions demonstrated a significantly higher number of cells with purinosomes in the G₁ phase, which was further confirmed by cell synchronization. HGPRT-deficient fibroblast cells also exhibited the greatest purinosome formation in the G₁ phase; however, elevated levels of purinosomes were also observed in the S and G₂/M phases. The observed variation in cell cycle-dependent purinosome formation between the two cell models tested can be attributed to differences in purine biosynthetic mechanisms. Our results demonstrate that purinosome formation is closely related to the cell cycle.Enzymes have been shown to form clusters in a cell to regulate metabolic processes (1–3). More recently, the concept of multienzyme complexes has been expanded to include mesoscale protein assemblies that appear to be substantially larger than a single protein (4). Depending on the metabolic or developmental state of the cells, these types of protein clusters range from transiently associated to very rigid and well defined (4). Examples of such enzyme clusters include the EF-Tu cytoskeleton, RNA degradosome, CTP synthase, carboxysomes, and nucleolus (5–9).In humans, purine nucleotides are synthesized by two different mechanisms. The first mechanism, de novo purine biosynthesis, converts phosphoribosylpyrophosphate (PRPP) to inosine 5′-phosphate (IMP) in 10 highly conserved steps catalyzed by six enzymes. These six enzymes include one trifunctional enzyme (TrifGART: GARS, GART, and AIRS domains), two bifunctional enzymes (PAICS: CAIRS and SAICARS domains; ATIC: AICART and IMPCH domains), and three monofunctional enzymes (PPAT, FGAMS, and ASL). ASL is also necessary for the conversion of IMP to AMP and may be classified as bifunctional (10). The second mechanism uses nucleotide salvage pathways to either phosphorylate a nucleoside (e.g., thymidine kinase) or add a purine base to ribose 5′-phosphate to regenerate the respective monophosphate. For example, hypoxanthine/guanine phosphoribosyl transferase (HGPRT) catalyzes the conversion of hypoxanthine to IMP and the conversion of guanine to guanosine 5′-phosphate (GMP). The de novo pathway is more energy-intensive, with the synthesis of 1 mole of IMP requiring 5 moles of ATP. Therefore, the salvage pathway is the preferred pathway for purine biosynthesis. Cells deficient in HGPRT, such as those that exhibit a Lesch–Nyhan disease (LND) phenotype, rely primarily on the de novo purine biosynthetic pathway to generate purine nucleotides (11–15).Recently, enzymes in the de novo purine biosynthetic pathway were shown to organize and reversibly assemble into punctate cellular bodies known as “purinosomes” under purine-depleted conditions (16). Further investigations into the organization of the purinosome showed that several of the enzymes form a core structure (PPAT, TrifGART, and FGAMS), whereas others appear to interact peripherally (PAICS, ASL, and ATIC) (17). The presence of this protein assembly and its putative function(s) clearly suggest that the spatial organization of pathway enzymes into purinosomes within a cell play an important role in meeting the cellular demand for purines (18). Although many studies have implied up-regulation of the de novo purine biosynthetic pathway during cell cycle progression (14, 19–21), here we used time-lapse microscopy to determine whether a correlation exists between the cell cycle stage and the number of cells with purinosomes or the cells’ purinosome content. Two different cell types, HeLa and LND cells, were used, with the latter deficient in purine salvage, to assess the effect of increased demand on the de novo pathway for purine biosynthesis and the attendant consequences for purinosome assembly.     

Clinical Translation of [68Ga]Ga-NOTA-anti-MMR-sdAb for PET/CT Imaging of Protumorigenic Macrophages

Molecular Imaging and Biology - Macrophage mannose receptor (MMR, CD206) expressing tumor-associated macrophages (TAM) are protumorigenic and was reported to negatively impact therapy...