Quantitative analysis of Pc 4 localization in mouse lymphoma (LY-R) cells via double-label confocal fluorescence microscopy

Photodynamic therapy (PDT) is a novel cancer therapy that uses light-activated drugs (photosensitizers) to destroy tumor tissue. Reactive oxygen species produced during PDT are thought to cause the destruction of tumor tissue. However, the precise mechanism of PDT is not completely understood. To provide insight into the in vitro mechanisms of PDT, we studied the subcellular localization of the photosensitizer HOSiPcOSi(CH3)2-(CH2)3N(CH3)2 (Pc 4) in mouse lymphoma (LY-R) cells using double-label confocal fluorescence microscopy. This technique allowed us to observe the relative distributions of Pc 4 and an organelle-specific dye within the same cell via two, spectrally distinct, fluorescence images. To quantify the localization of Pc 4 within different organelles, linear correlation coefficients from the fluorescence data of Pc 4 and the organelle-specific dyes were calculated. Using this measurement, the subcellular spatial distributions of Pc 4 could be successfully monitored over an 18 h period. At early times (0-1 h) after introduction of Pc 4 to LY-R cells, the dye was found in the mitochondria, lysosomes and Golgi apparatus, as well as other cytoplasmic membranes, but not in the plasma membrane or the nucleus. Over the next 2 h, there was some loss of Pc 4 from the lysosomes as shown by the correlation coefficients. After an additional incubation period of 2 h Pc 4 slowly increased its accumulation in the lysosomes. The highest correlation coefficient (0.65) was for Pc 4 and BODIPY-FL C5 ceramide, which targets the Golgi apparatus, and also binds to other cytoplasmic membranes. The correlation coefficient was also high (0.60) for Pc 4 and a mitochondria-targeting dye (Mitotracker Green FM). Both of these correlation coefficients were higher than that for Pc 4 with the lysosome-targeting dye (Lysotracker Green DND-26). The results suggest that Pc 4 binds preferentially and strongly to mitochondria and Golgi complexes.

Transcriptional repression of p21((Waf1/Cip1/Sdi1)) gene by c-jun through Sp1 site

Previously, we found that c-jun represses the tumor suppressor p21((Waf1/Cip1/Sdi1)) (p21) gene expression. In this study, we further investigated the mechanism of the inhibitory effect of c-jun on p21. After analysis of a series of deletion and point mutants of p21 promoter, we found that Sp1-3 site (-77 and -83) relative to the transcription start site played an important role for c-jun-repressing-responsive element in the p21 promoter. Both Sp1 and Sp3 transcription factors were the key factors for this event. However, the data from electrophoretic mobility shift assay indicated that c-jun did not change the Sp1 DNA-binding affinity, suggesting that additional factors may be involved in the repression of p21 by c-jun. Furthermore, c-jun could inhibit butyrate-inducing p21 gene expression through Sp1, indicating at least one common pathway whereby p21 expression is affected by c-jun and butyrate in opposing actions. Moreover, the hyperphosphorylated retinoblastoma protein (Rb) increased in c-jun expressing cells, indicating that phosphorylated Rb may play a role in regulating Sp1 to repress p21 expression. This is the first demonstration of how housekeeping factors and oncogene product counteract the function of tumor suppressor genes to control cell cycle progression.

Trimeric ring-like structure of ArsA ATPase

ArsA protein is the soluble subunit of the Ars anion pump in the Escherichia coli membrane which extrudes arsenite or antimonite from the cytoplasm. The molecular weight of the subunit is 63 kDa. In the cell it hydrolyzes ATP, and the energy released is used by the membrane-bound subunit ArsB to transport the substrates across the membrane. We have obtained two-dimensional crystals of ArsA in the presence of arsenite on negatively-charged lipid monolayer composed of DMPS and DOPC. These crystals have been studied using electron microscopy of negatively-stained specimens followed by image processing. The projection map obtained at 2.4 nm resolution reveals a ring-like structure with threefold symmetry. Many molecular assemblies with the same ring-shape and dimensions were also seen dispersed on electron microscopy grids, prepared directly from purified ArsA protein solution. Size-exclusion chromatography of the protein sample with arsenite present revealed that the majority of the protein particles in solution have a molecular weight of about 180 kDa. Based on these experiments, we conclude that in solution the ArsA ATPase with substrate bound is mainly in a trimeric form.

[Expression and characterization of HIV-1 Gag p17-p24 protein]

The biological and immunological characteristics of HIV-1 core protein p17-24 expressed by recombinant vaccinia viruses were studied. The results of indirect immunofluorescence assay (I-IFA), Western blot and dot ELISA showed that the two recombinants could express the p24 gag and p17-24 gag fusion proteins in infected cell lines respectively. The electromicroscope observation revealed that the expressed proteins could also assemble into virus-like particles. The recombinant vaccinia viruses can also stimulate mice for the formation of anti HIV-1 Gag p24 antibody. When infected with the recombinant viruses, the chromosome DNA ladder caused by the apoptosis of the BHK cell was observed.

The multiple roles of conserved arginine 286 of 1-aminocyclopropane-1-carboxylate synthase. Coenzyme binding, substrate binding, and beyond

A pyridoxal 5'-phosphate (PLP)-dependent enzyme, 1-aminocyclopropane-1-carboxylic acid (ACC) synthase (S-adenosyl-L-Met methylthioadenosine-lyase, EC 4.4.1.14), catalyzes the conversion of S-adenosyl-L-methionine (AdoMet) to ACC. A tomato ACC synthase isozyme (LE-ACS2) with a deletion of 46 amino acids at the C terminus was chosen as the control enzyme for the study of the function of R286 in ACC synthase. R286 of the tomato ACC synthase was mutated to a leucine via site-directed mutagenesis. The ACC synthase mutant R286L was purified using a simplified two-step purification protocol. Circular dichroism (CD) analysis indicated that the overall three-dimensional structure of the mutant was indistinguishable from that of the control enzyme. Fluorescence spectroscopy revealed that the binding affinity of R286L ACC synthase for its cofactor PLP was reduced 20- to 25-fold compared with control. Kinetic analysis of R286L showed that this mutant ACC synthase had a significantly reduced turnover number (k(cat)) of 8.2 x 10(-3) s(-1) and an increased K(m) of 730 microM for AdoMet, leading to an 8,000-fold decrease in overall catalytic efficiency compared with the control enzyme. Thus, R286 of tomato ACC synthase is involved in binding both PLP and AdoMet.

Quantitative laser scanning confocal autofluorescence microscopy of normal, premalignant, and malignant colonic tissues

Laser scanning confocal autofluorescence microscopy (LSCAM) using 351- to 364-nm excitation light was used to quantitatively compare fluorescent spectral emission of unstained, frozen histological sections of normal, premalignant, and malignant colonic tissues. To identify the spatial origins of fluorescent signals accurately, the same frozen section slides used for microscopy were fixed and histochemically stained immediately following LSCAM imaging. Tissue fluorescence emission was quantified in terms of the intrinsic fluorescence coefficient beta (lambda), defined as the fluorescence power per unit tissue volume per unit wavelength (centered at lambda) divided by the incident light irradiance. Over all emission wavelengths, colonic tissues emitted autofluorescence ranging from beta (lambda) approximately 10(-1.5) to 10(-3.0) cm-1. In the 530- to 610-nm spectral region, markedly increased autofluorescence (beta up to 10(-2.5)) was observed in the dysplastic cells of adenomatous polyps, as compared to normal epithelial cells. Compared to adenomatous polyps, decreased dysplastic cell autofluorescence was observed in adenocarcinoma. The brightest fluorescence in the lamina propria, which was attributed to eosinophils (beta approximately 10(-2.5)) in previous studies, was also observed in other granular structures (beta up to 10(-1.4)). LSCAM reveals quantitative significant differences in fluorescence emission between normal and diseased colonic tissues.

Pentameric two-dimensional crystallization of rabbit C-reactive protein on lipid monolayers

As a member of the pentraxin family, C-reactive protein plays various roles in the nonspecific immunity of animals. Though soluble, C-reactive protein always functions on membranes. In order to study the structure of the membrane-bound protein and the reaction between protein and membranes, two-dimensional (2D) crystallization of rabbit C-reactive protein on lipid monolayers was performed. The 2D crystals composed of pentameric proteins were obtained on lipid monolayers by specific adsorption for the first time. The projection map at 26-A resolution is presented, which exhibits P2 symmetry with lattice parameters a = 158(+/-3) A, b = 92(+/-1) A, and gamma = 107(+/-1) degrees. The current work may give a basis for the further study on the structure of complexes made up of C-reactive protein with its functional binding molecules on membranes.

The nature of the catalytic domain of 2'-5'-oligoadenylate synthetases

2'-5'-Oligoadenylate (2-5(A)) synthetases are a family of interferon-induced enzymes that are activated by double-stranded RNA. To understand why, unlike other DNA and RNA polymerases, they catalyze 2'-5' instead of 3'-5' phosphodiester bond formation, we used molecular modeling to compare the structure of the catalytic domain of DNA polymerase beta (pol beta) to that of a region of the P69 isozyme of 2-5(A) synthetase. Although the primary sequence identity is low, like pol beta, P69 can assume an alphabetabetaalphabetabetabeta structure in this region. Moreover, mutation of the three Asp residues of P69, which correspond to the three catalytic site Asp residues of pol beta, inactivated the enzyme without affecting its substrate and activator binding capacity, providing further credence to the concept that this region is the catalytic domain of P69. This domain is highly conserved among all 2-5(A) synthetase isozymes. Biochemical and mutational studies demonstrated that dimerization of the P69 protein is required for its enzyme activity. However, a dimer containing a wild type subunit and an inactive catalytic domain mutant subunit was also active. The rate of catalysis of the heterodimer was half of that of the wild type homodimer, although the two proteins bound double-stranded RNA and ATP equally well.

Reversal of hypertension by angiotensin II type 1 receptor antisense gene therapy in the adult SHR

Pharmacological blockade of the renin-angiotensin system in both hypertensive patients and animal models such as the spontaneously hypertensive rat (SHR) effectively reduces blood pressure (BP). Recent studies have established that virally mediated delivery (vector LNSV) of antisense to the angiotensin II type 1 receptor (LNSV-AT1R-AS) will attenuate or abolish the development of hypertension in the SHR. However, the effectiveness of this gene therapy approach to reduce high BP once it is established in the adult has not been ascertained. In this study, we investigated the hypothesis that viral delivery of AT1R-AS into the adult SHR will reduce BP and reverse the vascular reactivity associated with the hypertension. Intracardiac injection of virus particles containing LNSV-AT1R-AS into adult SHR resulted in a 30- to 60-mmHg reduction in BP that was maintained for up to 36 days compared with SHR treated with virus alone (LNSV without antisense). Measurement of renal resistance arteriolar reactivity demonstrated a leftward shift in the KCl and phenylephrine concentration-response relationships and an impaired endothelium-dependent relaxation to ACh in LNSV-treated SHR compared with control Wistar-Kyoto rats. These vascular alterations were reversed in the LNSV-AT1R-AS-treated SHR. Collectively, these data demonstrate that virally mediated gene delivery of AT1R-AS can effectively reduce BP and reverse renovascular pathophysiology associated with the hypertensive state when administered to the adult SHR.

Mitochondrial depolarization accompanies cytochrome c release during apoptosis in PC6 cells

Cytochrome c is released from mitochondria into the cytosol in cells undergoing apoptosis. The temporal relationship between cytochrome c release and loss of mitochondrial membrane potential was monitored by laser-scanning confocal microscopy in single living pheochromocytoma-6 cells undergoing apoptosis induced by staurosporine. Mitochondrial membrane potential monitored by tetramethylrhodamine methyl ester decreased abruptly in individual cells from 2 to 7 h after treatment with staurosporine. Depolarization was accompanied by cytochrome c release documented by release of transfected green fluorescent protein-tagged cytochrome c in these cells. The results show that mitochondrial depolarization accompanies cytochrome c release in pheochromocytoma-6 cells undergoing apoptosis.

Regulation of T lymphocyte trafficking into lymph nodes during an immune response by the chemokines macrophage inflammatory protein (MIP)-1 alpha and MIP-1 beta

By virtue of their target cell specificity, chemokines have the potential to selectively recruit leukocyte subpopulations into sites of inflammation. Their role in regulation of T lymphocyte traffic into lymph nodes during the development of an immune response has not previously been explored. The sensitization phase of contact hypersensitivity induced by the hapten, dinitrofluorobenzene (DNFB) in the mouse was used as a model of T lymphocyte trafficking in response to antigenic stimulation. Rapid accumulation of CD8+ and CD4+ T cells in the draining lymph nodes was closely associated with strongly enhanced expression of macrophage inflammatory protein (MIP)-1 alpha and MIP-1 beta mRNAs and proteins. Mast cells accumulating in the nodes during DNFB sensitization were the predominant source of MIP-1 beta, whereas MIP-1 alpha was expressed by multiple cell types. Neutralization of these chemokines profoundly inhibited T lymphocyte trafficking into lymph nodes and altered the outcome of a subsequent challenge to DNFB. Thus, beta-chemokines regulate T lymphocyte emigration from the circulation into lymph nodes during an immune response and contribute significantly to the immunologic outcome.

Mast cell activation and migration to lymph nodes during induction of an immune response in mice

The mast cell response in skin and lymph nodes was examined during the sensitization phase of dinitrofluorobenzene (DNFB)-induced contact hypersensitivity in mice. Degranulation of 62% of mast cells in DNFB-exposed skin was evident within 30 min of a dual application of DNFB, reaching a peak of 77% at 24 h, and persisting in 42% after 5 d. Abundant expression of macrophage inflammatory protein (MIP)-1alpha and MIP-1beta mRNAs and proteins was observed in keratinocytes, and mast cell degranulation was significantly inhibited after administration of neutralizing antibodies to MIP-1alpha, but not MIP-1beta. During DNFB sensitization, the mast cell density in the skin decreased by half, concurrent with a fivefold expansion of mast cell numbers in draining lymph nodes. Fluorescent-labeled mast cells injected into the skin appeared in draining lymph nodes after application of DNFB, followed by subsequent migration to the spleen. In lymph nodes, mast cells were an abundant and predominant source of MIP-1beta, neutralization of which partially inhibited T lymphocyte recruitment. These results indicate that mast cells contribute to the induction of this primary immune response by activation at and migration from the site of antigen encounter to draining lymph nodes, wherein they mediate T lymphocyte recruitment by production of MIP-1beta.

Effects of motorcycle exhaust on cytochrome P-450-dependent monooxygenases and glutathione S-transferase in rat tissues

The effects of motorcycle exhaust (ME) on cytochrome P-450 (P-450)-dependent monooxygenases were determined using rats exposed to the exhaust by either inhalation, intratracheal, or intraperitoneal administration. A 4-wk ME inhalation significantly increased benzo[a]pyrene hydroxylation, 7-ethoxyresorufin O-deethylation, and NADPH-cytochrome c reductase activities in liver, kidney, and lung microsomes. Intratracheal instillation of organic extracts of ME particulate (MEP) caused a dose- and time-dependent significant increase of monooxygenase activity. Intratracheal treatment with 0.1 g MEP extract/kg markedly elevated benzo[a]pyrene hydroxylation and 7-ethoxyresorufin O-deethylation activities in the rat tissues 24 h following treatment. Intraperitoneal treatment with 0.5 g MEP extract/kg/d for 4 d resulted in significant increases of P-450 and cytochrome b5 contents and NADPH-cytochrome c reductase activity in liver microsomes. The intraperitoneal treatment also markedly increased monooxygenases activities toward methoxyresorufin, aniline, benzphetamine, and erythromycin in liver and benzo[a]pyrene and 7-ethoxyresorufin in liver, kidney, and lung. Immunoblotting analyses of microsomal proteins using a mouse monoclonal antibody (Mab) 1-12-3 against rat P-450 1A1 revealed that ME inhalation, MEP intratracheal, or MEP intraperitoneal treatment increased a P-450 1A protein in the hepatic and extrahepatic tissues. Protein blots analyzed using antibodies to P-450 enzymes showed that MEP intraperitoneal treatment caused increases of P-450 2B, 2E, and 3A subfamily proteins in the liver. The ME inhalation, MEP intratracheal, or MEP intraperitoneal treatment resulted in significant increases in glutathione S-transferase activity in liver cytosols. The present study shows that ME and MEP extract contain substances that can induce multiple forms of P-450 and glutathione S-transferase activity in the rat.

Effects of capsaicin on human nasal mucosa

In order to determine the effects of capsaicin on the sympathetic innervation of human nasal mucosa, the effects of capsaicin on the contractile response of isolated human nasal mucosal blood vessels to field stimulation and methoxamine were investigated. Results showed that capsaicin enhanced field stimulation but there were no effects on mucosal contraction induced by methoxamine. Likewise, the drug had no effects on mucosal basal tension but potentiated mucosal contractions by norepinephrine. The study indicated that capsaicin may increase sympathetic function with the potentiating effects of norepinephrine. Because no effects of capsaicin on the resting tension of the nasal mucosa in vitro were noted, it is therefore deduced that local reactions in nasal mucosa by capsaicin in vivo should be via central or local reflexes.

Identification of the functional regions required for hepatitis D virus replication and transcription by linker-scanning mutagenesis of viral genome

To define the important cis-elements in hepatitis delta virus (HDV) RNA, the viral genome was mutated by a linker-scanning mutagenesis strategy that maintained the native rod-like structure of HDV RNA. Mutant HDV cDNAs or their corresponding RNA transcripts were transfected into a Huh-7-derived cell line which continuously expressed small hepatitis delta antigen to study the viral replication and transcription. Here we report the following findings. (i) Although most of the mutant RNAs could self-process to generate the 1.7-kb genomic RNA and all their stabilities were similar, positions which surround the genomic ribozyme domain were found to be important for the self-processing of the dimeric RNA. (ii) The replication of viral RNA was greatly diminished in many mutants, suggesting that multiple regions in HDV RNA were required for replication. (iii) In certain mutants, replication of the HDV antigenomic RNA was selectively abolished but that of the genomic RNA was not. Therefore, this was the first report to show that the cis-elements needed for the replication of genomic or antigenomic HDV RNA could be different. (iv) A continuous region (nt 1625 to nt 431), spanning the HDAg mRNA initiation site and containing the in vitro identified RNA promoter, was found to be important for mRNA production in vivo. (v) The HDV RNA replication and transcription was previously proposed to be governed by a single "double-acting promoter." However, two mutants which were deficient in mRNA synthesis still retained active viral RNA replication. It suggested that the HDV replication could initiate from sites other than this single promoter. This study therefore provided an insight into the cis-elements required for HDV RNA replication and transcription and further contributed to our understanding of HDV life cycle.

[Voltage dependence of late Na channel with burst mode in isolated cardiac myocytes]

Patch clamp technique was employed to record single Na channel currents in isolated guinea-pig ventricular myocytes. Burst mode could be elicited by step depolarization and terminates immediately after repolarization. The unitary current of burst mode was not only dependent on Na concentration in the pipettes but also on the test voltage. The open time constant increased as testing voltage becomes more positive. The results from stepwise-depolarization and ramp depolarization experiments showed that the more steps or the faster the upstroke velocity of depolarization used, the more the burst mode would occure.

Modulation of cytochrome P-450-dependent monooxygenases, glutathione and glutathione S-transferase in rat liver by geniposide from Gardenia jasminoides

Geniposide is an iridoid glycoside extracted from the fruits of Gardenia jasminoides, which are used as a food colorant and as a traditional Chinese medicine for treatment of hepatic and inflammatory diseases. The effects of geniposide and G. jasminoides fruit crude extract on liver cytochrome P-450 (P-450)-dependent monooxygenases, glutathione and glutathione S-transferase were investigated using rats treated orally with the iridoid glycoside (0.1 g/kg body weight/day) or the fruit crude extract (2 g/kg/day) for 4 days. The treatments decreased serum urea nitrogen level but increased liver to body weight ratio, total hepatic glutathione content and hepatic cytosolic glutathione S-transferase activity. Treatments with geniposide and G. jasminoides decreased P-450 content, benzo[a]pyrene hydroxylation, 7-ethoxycoumarin O-deethylation, and erythromycin N-demethylation activities in liver microsomes without affecting aniline hydroxylation activity. The natural products had no effect on glutathione content and monooxygenase activities in kidney microsomes. Immunoblotting analyses of liver microsomal proteins using mouse monoclonal antibody 2-13-1 to rat P4503A1/2 revealed that geniposide and G. jasminoides crude extract decreased the intensity of a P4503A-immunorelated protein. Protein blots probed with mouse monoclonal antibody 1-12-3 to rat P4501A1 and rabbit polyclonal antibody against human P4502E1 showed that both treatments had little or no effect on P4501A and 2E proteins. The present findings demonstrate that geniposide from G. jasminoides has the ability to inhibit a P4503A monooxygenase and increase glutathione content in rat liver.

Suppression of microsomal cytochrome P450-dependent monooxygenases and mitochondrial oxidative phosphorylation by fullerenol, a polyhydroxylated fullerene C60

The acute toxicity of fullerenol-1 was determined using mice pretreated intraperitoneally (i.p.) with polyhydroxylated C60 derivatives. The LD50 value of fullerenol-1 was estimated to be 1.2 g/kg. Pretreatments with 0.5 and 1.0 g/kg fullerenol-1 decreased cytochromes P450 and b5 contents, and NADPH-cytochrome P450 reductase, benzo[a]pyrene hydroxylase, 7-ethoxycoumarin O-deethylase, aniline hydroxylase, and erythromycin N-demethylase activities in liver microsomes. Pretreatments with 0.01 and 0.1 g/kg fullerenol-1 had no effect on these monooxygenases. Additions of fullerenol-1 to mouse liver microsomes suppressed monooxygenases activities toward benzo[a]pyrene, 7-ethoxycoumarin, aniline, and erythromycin with IC50 values of 42, 94, 102 and 349 microM, respectively. Fullerenol-1 exhibited noncompetitive and mixed-type of inhibition in benzo[a]pyrene hydroxylation and 7-ethoxycoumarin O-deethylation, respectively. Additions of fullerenol-1 to rat liver mitochondria resulted in a dose-dependent inhibition of ADP-induced uncoupling and markedly inhibited mitochondrial Mg2+ -ATPase activity with an IC50 value of 7.1 microM. These results demonstrate that fullerenol-1 can suppress the levels of the microsomal enzymes in vivo and decrease the activities of P450-dependent monooxygenase and mitochondrial oxidative phosphorylation in vitro.

[Effects of Andrographis paniculata component on nitric oxide, endothelin and lipid peroxidation in experimental atherosclerotic rabbits]

OBJECTIVE

To observe the effects of Andrographis Paniculata component (API0134) on nitric oxide (NO), endothelin (ET), cyclic guanosine monophosphate (cGMP), lipid peroxide (LPO) and superoxide dismutase (SOD) in experimental atherosclerotic rabbit.

METHODS

An atherosclerotic rabbit model was established by feeding high cholesterol diet supplemented by bovine serum albumin injection bolus. The rabbits were randomly divided into the control, model, and API0134 treated group. Blood samples were collected before 4 weeks and 8 weeks after relevent treatment.

RESULTS

Before 4 and after 8 weeks API0134 administration, compared with model group, the NO, cGMP and activity of SOD increased (P < 0.01), while LPO and ET decreased (P < 0.01).

CONCLUSIONS

API0134 possesses the effects of antioxidation, preserving endothelial function, and maintaining the balance of NO/ET.

Interaction of rabbit C-reactive protein with phospholipid monolayers studied by microfluorescence film balance with an externally applied electric field

C-reactive protein (CRP) is one of the most characteristic acute-phase proteins in humans and many other animals. It binds to phosphorylcholine in a calcium-dependent manner. In addition, CRP activates the complement systems via the classical pathway. The interaction between rabbit CRP (rCRP) and model biological membrane is studied using dimyristoylphosphatidylethanolamine and dipalmitoylphosphatidylcholine monolayers. Observations with fluorescence microscopy indicate that rCRP is more likely to be incorporated in the liquid phase of monolayers. Such incorporation does not depend on the presence of calcium and is not inhibited by phosphocholine. The area occupied by the protein when incorporated into the monolayer was estimated. The dipole moment density of the protein crossing the air/water interface was measured by applying an external electric field. Our results indicate that calcium binding leads to a conformational change in CPR, which might modify the orientation of CRP in the monolayer. In addition, a negative charge or negative difference in dipole moment density facilitates the incorporation of CPR into the monolayer.

Late-onset life-threatening angioedema and upper airway obstruction caused by angiotensin-converting enzyme inhibitor: report of a case

Angioedema is a rare but potentially lethal adverse effect when associated with upper airway obstruction. Sporadic cases of angioedema secondary to angiotensin converting enzyme inhibitors (ACEI) have been reported in the literature. The overall incidence is around 0.1% to 0.2%, and the time of onset is usually during the first week of ACEI therapy. Late-onset angioedema secondary to treatment with ACEIs is much more frequent than appreciated, and is largely unrecognized because of the absence of temporal correlation between ACEI therapy and the development of angioedema. Since angioedema may progress to upper airway obstruction, otolaryngologists must be aware of this association. Most importantly, late-onset angioedema should alert the clinician to discontinue the ACEI immediately to prevent further morbidity. This report presents an example of late-onset angioedema which was precipitated by taking a double dose of captopril incidentally. The case is discussed, and the literature, pathophysiology and treatment of angioedema are reviewed.

Four types of late Na channel current in isolated ventricular myocytes with reference to their contribution to the lastingness of action potential plateau

Patch clamp technique was employed to record single Na channel current in isolated guinea-pig ventricular myocytes. Four types of late Na channel currents were observed with whole cell and inside-out recording, which are (1) isolated brief openings, (2) scattered openings, (3) long openings and (4) bursts. The occurrence frequencies of the four types were different. Bursts appeared about 1 in every 2,000 depolarizations, with an open time constant longer than others. However, all the four types of late current openings, as well as the early openings occurring immediately upon depolarization, could be blocked by tetrodotoxin. It was also found that at a certain stimulation frequency, normal action potential duration (APD) was not invariable as supposed before, but varied from stimulation to stimulation. Special Na channel blocker, TTX, shortened the APD and refractory period and abolished the dispersion. The above results suggest that the activities of the various types of late Na channel play an important role in the formation of action potential plateau.

Effects of amphetamine on human nasal mucosa

The present study was devised to determine the effects of amphetamine on the sympathetic function of human nasal mucosa. A tissue bath method was employed on the vitro preparations of nasal turbinate mucosa from adult patients with nasal allergies or hypertrophic rhinitis. The effects of amphetamine on the contractile response of isolated human nasal mucosal blood vessels were investigated following electrical field stimulation and methoxamine. The results showed that amphetamine inhibited field stimulation and antagonized the effects on mucosal contraction induced by methoxamine. Likewise, the drug increased mucosal basal tension but had local drug toxicity when a 10(-4) M solution was used. Amphetamine could potentiate mucosal contraction induced by norepinephrine or epinephrine. The study indicated that amphetamine may increase sympathetic function by potentiating the effect of norepinephrine and that high concentration of amphetamine may actually antagonize alpha-adrenoceptors.

Noradrenergic innervation of nasal polyps and polypoid mucosae

In order to study the sympathetic innervation of nasal polyps and polypoid mucosae, the glyoxylic catecholaminergic histofluorescence method was employed in the examination of specimens taken from patients who had nasal disorders with polyps or polypoid mucosae. One percent neutral red was used as a counterstain. Abundant sympathetic fibers were present around the vessels of the pedicle of nasal polyps. However, no sympathetic innervation was found in the body and apex of the polyps. In the microscopical views of polypoid formations, there were no obvious differences between non-diseased nasal mucosa and polypoid mucosa in the distribution of sympathetic innervation. Based on these results, the following conclusions were drawn: (1) The loss of the sympathetic innervation was suggested to an important role in the pathogenesis of nasal polyps. (2) During polypectomy, the polyp had better be removed along with the pedicle for there is abundant sympathetic innervation and it will result in reduced bleeding.