Insights Into the Dehydration Behavior of Thiamine Hydrochloride (vitamin B1) Hydrates: Part II

Thiamine hydrochloride (THCl) can exist as an anhydrate (AH) and as a hemihydrate (HH). AH sorbs water as a function of environmental water vapor pressure to form a nonstoichiometric hydrate (NSH). NSH dehydration is initiated at ～40°C to yield AH, an isomorphic desolvate (ID) of NSH (Chakravaty et al., 2009, J Pharm Sci). Upon heating, dehydration of HH occurs only at elevated temperatures (>120°C) and is accompanied by chemical decomposition. When heated at reduced temperature (60–90°C) and pressure (20–760 mTorr), HH was incompletely dehydrated with partial loss of long‐range lattice order. Complete dehydration of HH to AH was achieved through a solvent‐mediated transformation in ethanol. The crystal structures of NSH and HH exhibit pronounced differences in the hydrogen bonding of water. The dehydration mechanism of NSH and HH can be explained by the “continuous and unified” dehydration model.¹⁰. © 2009 Wiley‐Liss, Inc. and the American Pharmacists Association J Pharm Sci 99: 1882–1895, 2010     

Regulation of the pulmonary circulation in the fetus and newborn

During the development of the pulmonary vasculature in the fetus, many structural and functional changes occur to prepare the lung for the transition to air breathing. The development of the pulmonary circulation is genetically controlled by an array of mitogenic factors in a temporo-spatial order. With advancing gestation, pulmonary vessels acquire increased vasoreactivity. The fetal pulmonary vasculature is exposed to a low oxygen tension environment that promotes high intrinsic myogenic tone and high vasocontractility. At birth, a dramatic reduction in pulmonary arterial pressure and resistance occurs with an increase in oxygen tension and blood flow. The striking hemodynamic differences in the pulmonary circulation of the fetus and newborn are regulated by various factors and vasoactive agents. Among them, nitric oxide, endothelin-1, and prostaglandin I(2) are mainly derived from endothelial cells and exert their effects via cGMP, cAMP, and Rho kinase signaling pathways. Alterations in these signaling pathways may lead to vascular remodeling, high vasocontractility, and persistent pulmonary hypertension of the newborn.     

Role of FAB classification of acute leukemias in era of immunophenotyping

French-American-British classification for leukemias had been widely accepted due to its objectiveness and good reproducibility. WHO classification of leukemias was formulated in 1997 with a purpose of further enhancing the objectivity. However, the requirement of cytogenetics and immunophenotyping makes it difficult for many countries like India to put WHO classification in routine use. This study was carried to know the effectiveness of FAB classification in an era of technical advancement. A retrospective analysis of all acute leukemias over a period of 2 years was done. Out of total of 469 cases of acute leukemias, 193 were diagnosed as Acute Lymphoblastic Leukemia (ALL), 200 as Acute Myeloid Leukemia (AML), and 76 cases diagnosed as Acute Leukemia, cytochemically undifferentiated. Hence, only 16% of all leukemias remained unclassifiable. Subclassification of AML cases revealed a much higher percentage of AML-M3, as compared to western literature. In conclusion, FAB classification, based on morphology and simple cytochemical stains, remains effective enough, although cytogenetics and immunophenotyping can add to diagnostic accuracy in some cases.     

Verapamil induces upregulation of P-glycoprotein expression on human monocyte derived dendritic cells

Overexpression of P-glycoprotein, a transmembrane drug efflux pump that mediates efflux of chemotherapeutic agents contributes to drug resistance in many leukaemia and other cancerous cells. Non-malignant cells including leukocytes also express P-glycoprotein, but physiologic functions for P-glycoprotein are poorly defined. Recently, P-glycoprotein expression has been described in human mononuclear phagocytes and Langerhans cells. It has been shown to play a role in phagocytic cell transmigration through endothelial-lined vessels in an ablumenal-lumenal direction, a process that mimics their migration into lymphatic vessels. Using the monoclonal antibody 4E3, and the P-glycoprotein antagonist, verapamil, the expression of P-glycoprotein on human monocyte-derived dendritic cells was evaluated. Dendritic cells used in this study were CD1a⁺, CD11c⁺, CD14^-, CD80⁺, CD83⁺, CD86⁺ and MHC-II^High. The expression of these markers increased significantly as the cells matured. P-glycoprotein expression was upregulated as the dendritic cells matured as well as in the presence of the “inflammatory stress” of the pathogenic bacteria Strept. pyogenes. Addition of verapamil or Strept. pyogenes to the culture medium during the final 24 hours significantly upregulated P-glycoprotein expression. Immortalized cell lines did not upregulate P-glycoprotein in the presence of verapamil. Evaluation of other normal cells showed that P-glycoprotein upregulation in the presence of verapamil was also a characteristic of macrophages. This novel observation of the upregulation of P-glycoprotein in the presence of verapamil appears to be a characteristic of activated myeloid derived antigen presenting cells and suggest that P-glycoprotein is essential for these cells as when it is blocked, they respond by increasing expression of this protein. In summary, this work describes that human dendritic cells generated from plastic-adherent monocytes rapidly upregulate expression of P-glycoprotein as they mature, and in the presence of inflammatory stress and the pharmacological agent verapamil, which blocks P-glycoprotein activity, suggesting that P-glycoprotein may play a role in activation as well as in migration of dendritic cells.     

Characterization of tissue-engineered scaffolds microfabricated with PAM

PAM (pressure-activated microsyringe) is a new microfabrication technique that allows the fabrication of two- and three-dimensional scaffolds with a well-defined geometry using polymers soluble in volatile solvents. In this study, polymeric scaffolds were realized with four different polymers--PCL, PLLA, PLGA, and a blend of PCL and PLLA--and with three different geometries-square grids, hexagonal grids, and octagonal grids. The scaffolds were characterized in terms of porosity, hydrophilicity, cell adhesion, and their mechanical properties. An analysis of the measured data shows that the physical and mechanical properties of the scaffold depend on its geometry and line width, both of which are easily modulated using PAM.     

Perioperative management of the patient with liver disease and management of the chronic alcoholic

Each year millions of Americans undergo surgical procedures requiring local, general, or spinal epidural anesthesia. A disproportionate number of the patients are older than age 65, and up to 10% of the patients have end-stage liver disease. Most patients do not suffer complications as a result of the surgical procedure or the anesthetic. However, about 3% to 10% of patients experience significant morbidity, often caused by infections or cardiac or pulmonary complications. Patients who have serious liver disease are generally believed to be at increased risk for perioperative morbidity and mortality. Appropriate preoperative evaluation is the cornerstone of successful intra- and postoperative management of the effects of anesthesia and surgery and is necessary for combating complications that may result from preexisting liver disease.     

Pharmacological characterization of novel water-soluble cannabinoids

Presently, there are numerous structural classes of cannabinoid receptor agonists, all of which require solubilization for experimental purposes. One strategy for solubilizing water-insoluble tetrahydrocannabinols is conversion of the phenolic hydroxyl to a morpholinobutyryloxy substituent. The hydrochloride salts of these analogs are water-soluble and active in vivo when administered in saline. The present investigation demonstrated that hydrochloride salts of numerous substituted butyryloxy esters are water-soluble and highly potent. The substitutions include piperidine, piperazine, and alkyl-substituted amino moieties. It was also discovered that incorporation of a nitrogenous moiety in the alkyl side chain increased the pharmacological potency of tetrahydrocannabinol. For example, an analog containing a pyrazole in the side chain (O-2545) was found to have high affinity and efficacy at cannabinoid 1 (CB(1)) and CB(2) receptors, and when dissolved in saline, it was highly efficacious when administered either intravenously or intracerebroventricularly to mice. A series of carboxamido and carboxylic acid amide analogs exhibited high pharmacological potency, but their hydrochloride salts were not water-soluble. On the other hand, incorporation of imidazoles into the terminus of the side chain led to water-soluble hydrochloride salts that were highly potent when administered in saline to laboratory animals. It is now possible to conduct cannabinoid research with agonists that are water-soluble and thus obviating the need of solubilizing agents.     

Novel compounds that interact with both leukotriene B4 receptors and vanilloid TRPV1 receptors

The aim of this study was to investigate the interaction of a series of novel compounds with leukotriene B(4) receptors (BLT) and vanilloid receptor (TRPV1). First, we characterized leukotriene B(4) (LTB(4)) ethanolamide. In guinea pig isolated lung parenchyma, LTB(4) ethanolamide antagonized the contractile action of LTB(4) with an apparent K(B) value of 7.28 nM. Using a Boyden chamber assay, we demonstrated that this compound stimulated human neutrophil migration in a similar manner to LTB(4) but with lower efficacy. In rat TRPV1 (rTRPV1)-expressing Chinese hamster ovary (CHO) cells and dorsal root ganglion (DRG) neurons, LTB(4) and LTB(4) ethanolamide acted as low-efficacy agonists, increasing intracellular calcium concentration ([Ca(2+)](i)) in a capsazepine-sensitive manner. These results prompted us to hypothesize that a molecule may possess pharmacophores such that it is capable of dual antagonism of BLT and TRPV1 receptors. Two novel compounds, N-[2-fluoro-4-[3-(11 hydroxyheptadec-8-enyl)-thioureiomethyl]-phenyl]-methanesulfonamide (O-3367) and N-[4-[3-(11 hydroxyheptadec-8-enyl)-thioureio-methyl]-phenyl]-methanesulfonamide (O-3383), were synthesized. In human neutrophils, both compounds acted as antagonists, significantly attenuating the BLT receptor-mediated ability of LTB(4) to induce migration, with pIC(50) values of 7.22 +/- 0.17 and 5.95 +/- 0.16, respectively. In rTRPV1-expressing CHO cells, they caused a significant rightward shift in the log concentration-response curve for the TRPV1 receptor agonist capsaicin (3-methoxy-4-hydroxy)benzyl-8-methyl-6-nonenamide). In DRG neurons O-3367 significantly attenuated the capsaicin-induced increases in [Ca(2+)](i) with a pIC(50) value of 5.94 +/- 0.004. O-3367 and O-3383 represent novel structural templates for generating compounds possessing dual antagonism at BLT and TRPV1 receptors. In view of the crucial role of both TRPV1 and BLT receptors in the pathophysiology of inflammatory conditions, such compounds may betoken a novel class of highly effective therapeutics.     

Ethanol destabilizes liver Gal beta l, 4GlcNAc alpha2,6-sialyltransferase, mRNA by depleting a 3'-untranslated region-specific binding protein

Asialoconjugates are viable biomarkers for alcohol abuse. We previously showed that chronic ethanol feeding down-regulated liver Gal beta l, 4GlcNAc alpha2,6-sialyltransferase (ST6Gal l) mRNA by destabilizing it. Since RNA-binding proteins are known to stabilize many eukaryotic mRNAs by interacting with the 3'-untranslated region (UTR), we have delineated the possible mechanism by which ethanol destabilizes ST6Gal l mRNA. Using (32)P-labeled RNA probes generated from a 2.7-kb 3'-UTR of ST6Gal l mRNA, we identified a liver cytosolic 41-kDa specific binding protein that interacts with its 3'-UTR domain and protects it from degradation in normal rat liver but disappears after chronic ethanol treatment. Mapping of the binding region revealed that four RNA probes of 80-base pair (bp) length spanning the 304 bp of the 3'-UTR of ST6Gal l mRNA showed equal binding intensity. The corresponding cDNA sequences for the four 80-bp RNA probes share the 13-bp consensus sequence. Mutagenesis analysis identified that four nucleotides, AG and TC, among the consensus sequences were critical for the RNA-protein interaction. Therefore, 5'-CAGCCTCCTCCCT-3' serves as a cis-element critically involved in this interaction. The RNA-protein complex formation progressively decreased with increasing dietary ethanol, resulting in its virtual disappearance with 36% of the dietary calories as ethanol. Concomitantly, the same ethanol diet decreased sialic acid index of plasma apolipoprotein J by 45% (p < 0.05). Thus, depletion of a binding protein that specifically interacts with its 3'-UTR region of ST6Gal l mRNA may account for its destabilization and consequent appearance of asialoconjugates as alcohol biomarkers.     

Sepsis-induced cholestasis, steatosis, hepatocellular injury, and impaired hepatocellular regeneration are enhanced in interleukin-6 -/- mice

OBJECTIVE: Hepatic dysfunction is an important but poorly understood component of sepsis. In severe sepsis, liver dysfunction is characterized by cholestasis, steatosis, hepatocellular injury, impaired regeneration, a decreased response to the cytokine interleukin-6, and high mortality. To determine whether loss of interleukin-6 activity caused hepatic dysfunction and mortality, we induced sepsis in wild-type (interleukin-6 +/+) and interleukin-6 knockout (interleukin-6 -/-) mice. We hypothesized that sepsis in interleukin-6 -/- mice would increase cholestasis, steatosis, hepatocellular injury, and mortality and impair hepatocyte regeneration. DESIGN: Randomized prospective experimental study. SETTING: University medical laboratory. SUBJECTS: Male adolescent C57Bl6 interleukin-6 +/+ and interleukin-6 -/- mice. INTERVENTIONS: Mild sepsis was induced using cecal ligation and single puncture (CLP). Severe, lethal sepsis was induced using cecal ligation and double puncture (2CLP). Some mice received recombinant human interleukin-6 at the time of CLP/2CLP. All animals were fluid resuscitated at the time of surgery and every 24 hrs thereafter. In survival cohorts, mortality at 16, 24, 48, and 72 hrs was recorded. In separate cohorts, surviving animals were killed at 24 and 48 hrs, and liver tissue was harvested. A separate cohort of mice received bromodeoxyuridine for detection of regeneration. MEASUREMENTS AND MAIN RESULTS: 2CLP was 100% fatal within the first 12 hrs in interleukin-6 -/- mice. Mortality from 2CLP in interleukin-6 +/+ mice before 24 hrs was nil but was 90% by 72 hrs. At 72 hrs, CLP was 40% fatal in interleukin-6 +/+ mice but 90% in interleukin-6 -/- mice. CLP induced cholestasis, steatosis, and hepatocellular injury in interleukin-6 -/-, but not interleukin-6 +/+, mice. Regeneration was absent following CLP in interleukin-6 -/- animals but occurred in interleukin-6 +/+ mice. Early administration of recombinant human interleukin-6 did not reverse abnormalities in interleukin-6 -/- mice. CONCLUSIONS: The absence of interleukin-6 is an important determinant of hepatic dysfunction and mortality in sepsis.