Pharmacokinetic study of iminodibenzyl antipsychotic drugs,clocapramine and Y-516 in dog and man

The pharmacokinetic properties of the iminodibenzyl antipsychotic drugs clocapramine (CCP, 3-chloro-5-[3-(4-carbamoyl-4-piperidino piperidino) propyl]-10, 11-dihydro-5H-dibenzo[b, f]azepine) and Y-516 (3-chloro-5-[3-(2-oxo-1, 2, 3, 5, 6, 7, 8, 8a-octahydroimidazo [1,2-a] pyridine-3-spiro-4-piperidino) propyl]-10, 11-dihydro-5H-dibenzo[b, f]azepine) were investigated in dog and man. Dogs were administered CCP and Y-516 intravenously, intraperitoneally, and orally, and the concentrations of the parent drugs and their metabolites in the plasma and urine were determined. Half-life (t1/2) was approximately the same by all three administration routes, being approximately 5 h for CCP and 3 h for Y-516. Bioavailability following oral administration was 0.16±0.01 (mean ± SD, n=3) for CCP and 0.29±0.07 for Y-516. The fractions of dose absorbed following oral administration were 0.43±0.07 and 0.79±0.24, and the fractions of dose metabolized in the liver due to the first-pass effect were 0.63±0.05 and 0.63±0.04 for CCP and Y-516, respectively. Y-516 was detected in the plasma after intraperitoneal and oral administration of CCP. The ratio of the AUC of Y-516 to that of CCP was 0.06 following intraperitoneal administration and 0.40 following oral administration. This indicated that while the metabolism of CCP into Y-516 may occur partly in the liver due to the first-pass effect, it occurs mostly within the gastrointestinal tract itself or its mucosa. When CCP and Y-516 were given orally to man, the plasma concentrations of both parent drugs increased in a dose-dependent manner. The t1/2 of CCP at a dose of 50 mg was 46±6 h (n=3) while that of Y-516 at a dose of 25 mg was 15±2 h (n=5), so that elimination from the circulation was slower than in the dog in both cases. As in the dog, Y-516 was detected in the plasma following administration of CCP, but its concentration was approximately one fifth that of CCP and lower than that found in the dog. From the ratios of Y-516 produced upon oral administration of CCP in dog and man, we concluded that Y-516 is involved to a considerable degree in the pharmacological action of CCP in the dog and, though to a lesser degree, in man as well.     

Dual β-Catenin and γ-Catenin Loss in Hepatocytes Impacts Their Polarity through Altered Transforming Growth Factor-β and Hepatocyte Nuclear Factor 4α Signaling

Hepatocytes are highly polarized epithelia. Loss of hepatocyte polarity is associated with various liver diseases, including cholestasis. However, the molecular underpinnings of hepatocyte polarization remain poorly understood. Loss of β-catenin at adherens junctions is compensated by γ-catenin and dual loss of both catenins in double knockouts (DKOs) in mice liver leads to progressive intrahepatic cholestasis. However, the clinical relevance of this observation, and further phenotypic characterization of the phenotype, is important. Herein, simultaneous loss of β-catenin and γ-catenin was identified in a subset of liver samples from patients of progressive familial intrahepatic cholestasis and primary sclerosing cholangitis. Hepatocytes in DKO mice exhibited defects in apical-basolateral localization of polarity proteins, impaired bile canaliculi formation, and loss of microvilli. Loss of polarity in DKO livers manifested as epithelial-mesenchymal transition, increased hepatocyte proliferation, and suppression of hepatocyte differentiation, which was associated with up-regulation of transforming growth factor-β signaling and repression of hepatocyte nuclear factor 4α expression and activity. In conclusion, concomitant loss of the two catenins in the liver may play a pathogenic role in subsets of cholangiopathies. The findings also support a previously unknown role of β-catenin and γ-catenin in the maintenance of hepatocyte polarity. Improved understanding of the regulation of hepatocyte polarization processes by β-catenin and γ-catenin may potentially benefit development of new therapies for cholestasis.

A hallmark of epithelial cells is polarization, which is achieved by the orchestration of external cues, such as cellular contact, extracellular matrix, signal transduction, growth factors, and spatial organization.¹ Hepatocytes in the liver show a unique polarity by forming several apical and basolateral poles within a cell.² The apical poles of adjacent hepatocytes form a continuous network of bile canaliculi into which bile is secreted, whereas the basolateral membrane domain forms the sinusoidal pole, which secretes various components, such as proteins or drugs, into the blood circulation.³ Loss of hepatic polarity has been associated with several cholestatic and developmental disorders, including progressive familial intrahepatic cholestasis (PFIC) and primary sclerosing cholangitis (PSC).^4,5 Although the molecular mechanisms governing hepatocyte polarity have been extensively studied in the in vitro systems, there is still a significant gap in our understanding of how polarity is established within the context of tissue during development or maintained during homeostasis.^6,7 Similarly, the molecular pathways contributing to hepatic polarity are not entirely understood, and a better comprehension of hepatic polarity regulation is thus warranted.Previous studies have confirmed the role of hepatocellular junctions, such as tight and gap junctions, in the maintenance of hepatocyte polarity.^8,9 Studies done in vitro and in vivo have shown that loss of junctional proteins, such as zonula occludens protein (ZO)-1, junctional adhesion molecule-A, and claudins, lead to impairment of polarity and distorted bile canaliculi formation.10, 11, 12, 13 In addition, proteins involved in tight junction assembly, such as liver kinase B1, are also involved in polarity maintenance.¹⁴ Among adherens junction proteins, various in vitro cell culture models have confirmed the role of E-cadherin in the regulation of hepatocyte polarity, possibly through its interaction with β-catenin.^15,16 However, there is a lack of an in vivo model to study the role of adherens junction proteins in hepatocyte polarity and their misexpression contributing to various liver diseases.β-Catenin plays diverse functions in the liver during development, regeneration, zonation, and tumorigenesis.17, 18, 19 The relative contribution of β-catenin as part of the adherens junction is challenging to study because like in other tissues, γ-catenin compensates for the β-catenin loss in the liver.^20,21 To address this redundancy, we previously reported a hepatocyte-specific β-catenin and γ-catenin double-knockout (DKO) mouse model was reported.²² Simultaneous deletion of β-catenin and γ-catenin in mice livers led to cholestasis, partially through the breach of cell-cell junctions. However, more comprehensive understanding of the molecular underpinnings of the phenotype is needed.In the current study, prior preclinical findings of dual β-catenin and γ-catenin loss were extended to a subset of PFIC and PSC patients. In vivo studies using the murine model with hepatocyte-specific dual loss of β-catenin and γ-catenin showed complete loss of hepatocyte polarity compared to the wild-type controls (CONs). Loss of polarity in DKO liver was accompanied by epithelial-mesenchymal transition (EMT), activation of transforming growth factor (TGF)-β signaling, and reduced expression of hepatocyte nuclear factor 4α (HNF4α). Our findings suggest that β-catenin and γ-catenin and in turn adherens junction integrity, are critical for the maintenance of hepatocyte polarity, and any perturbations in this process can contribute to the pathogenesis of cholestatic liver disease.     

Nasal congestion as a side effect of cromolyn sodium

Cromolyn sodium, a recently introduced antiasthmatic medication, is known occasionally to produce maculopapular and urticarial rashes, and increased bronchospasm. A patient is reported with a previously unpublished side effect of this medication, i.e., severe nasal congestion.     

Adrenaline turnover rates in the medial preoptic area and mediobasal hypothalamus in relation to the release of luteinizing hormone in female rats

The turnover rates of adrenaline in the medial preoptic area and mediobasal hypothalamus, areas which, respectively, include the cell bodies and terminals of luteinizing hormone-releasing hormone neurons, have been measured in female rats on pro-oestrus, the day of the preovulatory surge of luteinizing hormone, and on dioestrus, the preceding day. A rise in the rate of turnover was found in the medial preoptic area coinciding with the surge of luteinizing hormone in the late afternoon of pro-oestrus; the rate of turnover at this time was higher than at the same time on dioestrus. No changes in turnover rate were found in the mediobasal hypothalamus within either of these days.The results indicate that the adrenaline-containing projections to the preoptic area may be actively involved in the production of the spontaneous preovulatory surge of luteinizing hormone in rats.     

Egg allergy, influenza vaccine, and immunoglobulin E antibody.

In a study of 70 patients with asthma, rhinitis, and eczema, those giving a definite history of allergic reactions to egg more frequently showed positive skin tests to egg extracts (p = less than 0.003), the wheal diameters of which were significantly larger (p = less than 0.01) than in patients with only a possible or no such history. Patients with a definite history of egg allergy had significantly higher levels of specific IgE antibody against egg yolk, egg white, and allantoic fluid than patients in the other two groups (p = less than 0.005). Seven patients, all of whom had given a definite history of allergy to egg, were found to have positive skin prick tests to influenza vaccine, at the concentration used in medical practice. Two of these patients had previously been given influenza vaccine and both had developed adverse reactions. Of the 22 patients giving a definite history of allergy to egg, the 7 (35 per cent) with positive skin tests to influenza vaccine had significantly larger skin tests and higher levels of specific IgE antibody to the egg extracts than the group as a whole (p = less than 0.001). Allergic reactions to influenza vaccine are likely to occur in patients who have a definite history of allergy to egg and large skin prick test reactions or high levels of specific IgE antibody to egg extracts. Those at risk can best be identified by skin prick testing with egg extracts and undiluted influenza vaccine.     

Lymphopenia in acute nitrofurantoin pleuropulmonary reactions

Each of 5 patients with acute nitrofurantoin pleuropulmonary reactions had profound lymphopenia and 4 had eosinophilia developing early in the clinical course after the drug was withdrawn. The 2 patients tested had only one third of the normal numbers of E rosettes (T lymphocytes) in the peripheral blood during recovery. Lymphoblastic transformation tests with purified nitrofurantoin were done in 3 patients and all of them were negative; responses to phytohemagglutinin, concanavalin A, and pokeweed were decreased but still normal. The diagnosis of various nitrofurantoin hypersensitivity reactions relies on clinical data. The mechanisms of these reactions presently remain unclear.