Metabolic activation of fluoropyrrolidine dipeptidyl peptidase-IV inhibitors by rat liver microsomes.

The current study evaluated the potential for two dipeptidyl peptidase-IV (DPP-IV) inhibitor analogs (1S)-1-(trans-4-([(4-trifluoromethoxyphenyl)sulfonyl]amino)cyclohexyl)-2-[(3S)-3-fluoropyrrolidin-1-yl]-2-oxoethanaminium chloride and (1S)-1-(trans-4-([(2,4-difluorophenyl)sulfonyl]amino)cyclohexyl)-2-[(3S)-3-fluoropyrrolidin-1-yl]-2-oxoethanaminium chloride (MRL-A and MRL-B), containing a fluoropyrrolidine moiety in the structure, to undergo metabolic activation. The irreversible binding of these tritium-labeled compounds to rat liver microsomal protein was time- and NADPH-dependent and was attenuated by the addition of reduced glutathione (GSH) or N-acetylcysteine (NAC) to the incubation, indicating that chemically reactive intermediates were formed and trapped by these nucleophiles. Mass spectrometric analyses and further trapping experiments with semicarbazide indicated that the fluoropyrrolidine ring had undergone sequential oxidation and defluorination events resulting in the formation of GSH or NAC conjugates of the pyrrolidine moiety. The bioactivation of MRL-A was catalyzed primarily by rat recombinant CYP3A1 and CYP3A2. Pretreatment of rats with prototypic CYP3A1 and 3A2 inducers (pregnenolone-16alpha-carbonitrile and dexamethasone) enhanced the extent of bioactivation which, in turn, led to a higher degree of in vitro irreversible binding to microsomal proteins (5- and 9-fold increase, respectively). Herein, we describe studies that demonstrate that the fluoropyrrolidine ring is prone to metabolic activation and that GSH or NAC can trap the reactive intermediates to form adducts that provide insight into the mechanisms of bioactivation.     

Simulated apoptosis/neurogenesis regulates learning and memory capabilities of adaptive neural networks.

Characterization of neuronal death and neurogenesis in the adult brain of birds, humans, and other mammals raises the possibility that neuronal turnover represents a special form of neuroplasticity associated with stress responses, cognition, and the pathophysiology and treatment of psychiatric disorders. Multilayer neural network models capable of learning alphabetic character representations via incremental synaptic connection strength changes were used to assess additional learning and memory effects incurred by simulation of coordinated apoptotic and neurogenic events in the middle layer. Using a consistent incremental learning capability across all neurons and experimental conditions, increasing the number of middle layer neurons undergoing turnover increased network learning capacity for new information, and increased forgetting of old information. Simulations also showed that specific patterns of neural turnover based on individual neuronal connection characteristics, or the temporal-spatial pattern of neurons chosen for turnover during new learning impacts new learning performance. These simulations predict that apoptotic and neurogenic events could act together to produce specific learning and memory effects beyond those provided by ongoing mechanisms of connection plasticity in neuronal populations. Regulation of rates as well as patterns of neuronal turnover may serve an important function in tuning the informatic properties of plastic networks according to novel informational demands. Analogous regulation in the hippocampus may provide for adaptive cognitive and emotional responses to novel and stressful contexts, or operate suboptimally as a basis for psychiatric disorders. The implications of these elementary simulations for future biological and neural modeling research on apoptosis and neurogenesis are discussed.     

Probenecid Inhibits Respiratory Syncytial Virus (RSV) Replication

RNA viruses like SARS-CoV-2, influenza virus, and respiratory syncytial virus (RSV) are dependent on host genes for replication. We investigated if probenecid, an FDA-approved and safe urate-lowering drug that inhibits organic anion transporters (OATs) has prophylactic or therapeutic efficacy to inhibit RSV replication in three epithelial cell lines used in RSV studies, i.e., Vero E6 cells, HEp-2 cells, and in primary normal human bronchoepithelial (NHBE) cells, and in BALB/c mice. The studies showed that nanomolar concentrations of all probenecid regimens prevent RSV strain A and B replication in vitro and RSV strain A in vivo, representing a potential prophylactic and chemotherapeutic for RSV.     

Fender-kicker syndrome

Two patients with metatarsal and phalangeal fractures are reported. The unusual etiology of the fractures was the same in both cases. The condition for which we suggest the title “Fender-Kicker” syndrome, is probably a common though frequently unrecognized entity.     

Lipid synovial effusion unique occurrence in systemic lupus erythematosus

A patient who had systemic lupus erythematosus developed an acute synovitis symptomatically resembling septic arthritis: however, the synovial effusion was chylous, a unique occurrence. Significant differences, quantitatively and qualitatively, between the lipids of the blood and those of the synovial fluid suggested the possibility of synthesis of the lipids in synovial tissues.     

Chemotherapy-Induced Neutropenia and Febrile Neutropenia in the US: A Beast of Burden That Needs to Be Tamed?

Neutropenia and febrile neutropenia (FN) are common complications of myelosuppressive chemotherapy. This review provides an up-to-date assessment of the patient and cost burden of chemotherapy-induced neutropenia/FN in the US, and summarizes recommendations for FN prophylaxis, including the interim guidance that was recommended during the coronavirus disease 2019 (COVID-19) pandemic. This review indicates that neutropenia/FN place a significant burden on patients in terms of hospitalizations and mortality. Most patients with neutropenia/FN presenting to the emergency department will be hospitalized, with an average length of stay of 6, 8, and 10 days for elderly, pediatric, and adult patients, respectively. Reported in-hospital mortality rates for neutropenia/FN range from 0.4% to 3.0% for pediatric patients with cancer, 2.6% to 7.0% for adults with solid tumors, and 7.4% for adults with hematologic malignancies. Neutropenia/FN also place a significant cost burden on US healthcare systems, with average costs per neutropenia/FN hospitalization estimated to be up to $40 000 for adult patients and $65 000 for pediatric patients. Evidence-based guidelines recommend prophylactic granulocyte colony-stimulating factors (G-CSFs), which have been shown to reduce FN incidence while improving chemotherapy dose delivery. Availability of biosimilars may improve costs of care. Efforts to decrease hospitalizations by optimizing outpatient care could reduce the burden of neutropenia/FN; this was particularly pertinent during the COVID-19 pandemic since avoidance of hospitalization was needed to reduce exposure to the virus, and resulted in the adaptation of recommendations to prevent FN, which expanded the indications for G-CSF and/or lowered the threshold of use to >10% risk of FN.     

SOME ULTRAVIOLET PHOTOMICROGRAPHS OF B. SUBTILIS

1. Type-specific antipneumococcus immunity has been induced in rabbits by immunization with antigen prepared by combining a specific derivative of the capsular polysaccharide of Type III Pneumococcus with globulin from horse serum. 2. Rabbits immunized with this antigen acquire active immunity against infection with virulent Type III pneumococci. 3. The sera of the immune rabbits contain type-specific antibodies which precipitate the Type III capsular polysaccharide, agglutinate Type III pneumococci, and specifically protect mice against Type III infection. 4. The experimental data are discussed with reference to: (1) the concurrence in the immune sera of type-specific antibodies for Pneumococcus and precipitins for horse globulin; (2) the determining influence of the capsular polysaccharide on the specificity of the antigen as a whole; (3) the unity of the type-specific precipitins, agglutinins, and protective antibodies induced by a single compo of the pneu mococcus in chemical union with an unrelated, animal protein.