Decreased nitric-oxide synthase activity causes impaired endothelium-dependent relaxation in the postischemic heart

Endothelial nitric-oxide synthase (eNOS) is an important regulator of endothelial function and vascular tone in biological tissues. While endothelial dysfunction occurs following ischemia and has been attributed to altered NO. formation, the biochemical basis for this dysfunction is unknown. Therefore, studies were performed to determine the effects of myocardial ischemia and reperfusion on eNOS in isolated rat hearts subjected to periods of global ischemia or ischemia followed by reperfusion. eNOS activity was assayed by L-[14C]arginine to L-[14C]citrulline conversion and alterations in the amount and distribution of eNOS determined by Western blotting and immunohistochemistry. While activity was preserved after 30 min of ischemia with a value of 1.1 +/- 0.1 pmol x min-1 x mg of protein-1, it decreased by 77% after 60 min and became nearly undetectable after 120 min. Reperfusion resulted in only a partial restoration of activity. The decline in activity with ischemia was due, in part, to a loss of eNOS protein. Hemodynamic studies showed that the onset of impaired vascular reactivity paralleled the loss of functional eNOS. Subjecting isolated eNOS to conditions of acidosis, which occur during ischemia, followed by restoration of pH as occurs on reperfusion, caused a combination of reversible and irreversible loss of activity similar to that seen in ischemic and reperfused hearts. Thus, loss of endothelial function following ischemia is paralleled by a loss of eNOS activity due to a combination of pH-dependent denaturation and proteolysis.

RelB regulation of chemokine expression modulates local inflammation

The resolution of acute inflammation is incompletely understood but presumably requires the elimination of both inflammatory cells and production of inflammatory cytokines. In the case of recruited bone-marrow-derived inflammatory cells such as granulocytes and macrophages, their short life span helps eliminate these cells and the cytokines they produce. By contrast, resident permanent cells such as fibroblasts require other mechanisms to stop the production of chemokines generated in response to inflammatory triggers such as lipopolysaccharide. Here we demonstrate that RelB is an important regulator of chemokine expression in fibroblasts, thereby playing a key role in the resolution of acute inflammation. Activation of normal fibroblasts by lipopolysaccharide induced a transient production of chemokines, closely followed by induction of RelB expression. However, stimulated RelB-/- fibroblasts exhibited dramatic persistent induction of seven chemokines (RANTES, MIP-1 alpha, MIP-1 beta, MIP-2, IP-10, JE/MCP-1, and KC/CINC). The persistent overexpression of chemokines correlated with increased NF- kappa B binding as well as with increased p50, p65/RelA, and I kappa B alpha expression. Transfection of RelB cDNA into RelB-deficient fibroblasts reversed the lipopolysaccharide-induced chemokine overexpression. In vivo, activated RelB-/- fibroblasts dramatically increased recruitment of granulocytes into tissues. In view of the apparent role of RelB in the resolution of acute inflammation in tissues and previous work showing a requirement for RelB in the initiation of immune responses through the differentiation of antigen-presenting cells, RelB may be an important factor regulating the transition from innate to adaptive immunity.

Inhibition of constitutive nitric oxide synthase (NOS) by nitric oxide generated by inducible NOS after lipopolysaccharide administration provokes renal dysfunction in rats

Excess NO generation plays a major role in the hypotension and systemic vasodilatation characteristic of sepsis. Yet the kidney response to sepsis is characterized by vasoconstriction resulting in renal dysfunction. We have examined the roles of inducible nitric oxide synthase (iNOS) and endothelial NOS (eNOS) on the renal effects of lipopolysaccharide administration by comparing the effects of specific iNOS inhibition, -N6-(1-iminoethyl)lysine (L-NIL), and 2,4-diamino6-hydroxy-pyrimidine vs. nonspecific NOS inhibitors (nitro- -arginine-methylester). cGMP responses to carbamylcholine (CCh) (stimulated, basal) and sodium nitroprusside in isolated glomeruli were used as indices of eNOS and guanylate cyclase (GC) activity, respectively. LPS significantly decreased blood pressure and GFR (112+/-4 vs. 83+/-4 mmHg; 2.66+/-0.29 vs. 0. 96+/-0.22 ml/min, P < 0.05) and inhibited the cGMP response to CCh. GC activity was reciprocally increased. L-NIL and 2, 4-diamino-6-hydroxy-pyrimidine administration prevented the decrease in GFR (2.71+/-0.28 and 3.16+/-0.18 ml/min, respectively), restored the normal response to CCh, and GC activity was normalized. In vitro application of L-NIL also restored CCh responses in LPS glomeruli. Neuronal NOS inhibitors verified that CCh responses reflected eNOS activity. L-NAME, a nonspecific inhibitor, worsened GFR (0.41+/-0.15 ml/min), a reduction that was functional and not related to glomerular thrombosis, and eliminated the CCh response. No differences were observed in eNOS mRNA expression among the experimental groups. Selective iNOS inhibition prevents reductions in GFR, whereas nonselective inhibition of NOS further decreases GFR. These findings suggest that the decrease in GFR after LPS is due to local inhibition of eNOS by iNOS, possibly via NO autoinhibition.

Disruption of monolayer integrity enables activation of a cystic fibrosis "bypass" channel in human airway epithelia

Cystic fibrosis (CF) is a genetic disease characterized by marked reduction in Cl- conductance across many epithelia. Two kinds of Cl- channels have been associated with CF. One channel, termed the cystic fibrosis transmembrane conductance regulator (CFTR), is directly coded by the CF gene. The other channel is an outwardly rectifying depolarization induced Cl- channel (ORDIC) that is distinguished from other outwardly rectifying chloride channels (ORCCs) because its activity is induced most reliably by patch excision and depolarization. An issue in current CF research is whether ORDIC channels are indirectly activated by CFTR to contribute a significant portion of apical membrane Cl- conductance in airway cells. We now show that ORDIC channels are readily activated in patches excised and depolarized from isolated cells, but are rarer or refractory to activation in patches from the apical membranes of confluent human airway epithelia. These findings have important implications for proposed therapies that would bypass the CFTR conductance by activating ORDIC channels.

Genetic association of the low-density lipoprotein receptor-related protein gene (LRP), an apolipoprotein E receptor, with late-onset Alzheimer's disease

The presence of the APOE epsilon 4 allele encoding apolipoprotein E4 (apoE4) is the major genetic risk factor for late-onset Alzheimer's disease (AD). However, the molecular and cellular mechanisms by which APOE epsilon 4 renders AD risk are unclear. In this report, we present genetic evidence that an apoE receptor, LRP, may be associated with the expression of late-onset AD. Using a biallelic genetic marker in exon 3 of LRP, late-onset AD cases markedly differed from the control subjects in the distribution of LRP genotypes, and this difference was highly accentuated among AD cases with positive family history of senile dementia. Furthermore, the numbers of neutritic plaques were significantly altered as a consequence of different LRP genotypes in postmortem AD cases. Taken together, our results implicate the pathophysiology of LRP in the expression of late-onset AD.

Superoxide and peroxynitrite generation from inducible nitric oxide synthase in macrophages

Superoxide (O-2) and nitric oxide (NO) act to kill invading microbes in phagocytes. In macrophages NO is synthesized by inducible nitric oxide synthase (iNOS, NOS 2) from L-arginine (L-Arg) and oxygen; however, O-2 was thought to be produced mainly by NADPH oxidase. Electron paramagnetic resonance (EPR) spin trapping experiments performed in murine macrophages demonstrate a novel pathway of O-2 generation. It was observed that depletion of cytosolic L-Arg triggers O-2 generation from iNOS. This iNOS-mediated O-2 generation was blocked by the NOS inhibitor N-nitro-L-arginine methyl ester or by L-Arg, but not by the noninhibitory enantiomer N-nitro-D-arginine methyl ester. In L-Arg-depleted macrophages iNOS generates both O-2 and NO that interact to form the potent oxidant peroxynitrite (ONOO-), which was detected by luminol luminescence and whose formation was blocked by superoxide dismutase, urate, or L-Arg. This iNOS-derived ONOO- resulted in nitrotyrosine formation, and this was inhibited by iNOS blockade. iNOS-mediated O-2 and ONOO- increased the antibacterial activity of macrophages. Thus, with reduced L-Arg availability iNOS produces O-2 and ONOO- that modulate macrophage function. Due to the existence of L-Arg depletion in inflammation, iNOS-mediated O-2 and ONOO- may occur and contribute to cytostatic/cytotoxic actions of macrophages.

Age and gender differences in the self-esteem of Chinese children

A Chinese version of the Self-Description Questionnaire 1 (SDQ-1; Marsh, 1988) was used to investigate age and gender differences in a sample of 303 male and 296 female 10-year-old children and 116 male and 116 female 13-year-old children attending typical Beijing public schools. Significant Age x Gender interaction effects were found on all 8 SDQ-1 scales. Main effects for age were found on the Physical Abilities, Reading, and School subscales and for gender on the same three subscales plus Peer Relations. Further analysis indicated that the older girls tended to report significantly lower self-esteem than both the younger girls and older boys in the areas of physical abilities, reading, mathematics, and general self-concept. The boys reported more positive self-perceptions on most nonacademic self-scales, but both the older boys and older girls reported less favorable self-esteem than their younger peers on the scales for reading and school in general.

[The inhibition effect of foreign retinoblastoma gene mediated by recombinant adenovirus vector on the growth of smooth muscle cells]

OBJECTIVE

To study the effect of foreign retinoblastoma (Rb) gene mediated by recombinant adenovirus vector on vascular smooth muscle cell (SMC) and the possibility by using Rb gene for gene therapy of atherosclerosis and artery restenosis.

METHODS

Rb gene recombinant adenovirus vector was constructed to transfect into rabbits' aortic SMC in vitro. The efficiency of transfection and expression was detected by biochemical staining, immunocytochemical analysis and polymerase chain reaction technique. The role of Rb gene for SMC proliferation, DNA synthesis and cell cycle were observed by cell counting. 3H-incorporation and cytometer respectively.

RESULTS

Adenovirus vector transfered the Rb gene into SMC effectively. The expression of Rb gene restricted the proliferation of SMC, decreased the DNA synthesis and plaaied a role in the cell cycle.

CONCLUSION

Rb gene mediated by adenovirus can be used to treat atherosclerosis.

[Saline load test for diet instruction in patients with essential hypertension]

The saline loading test was performed in 53 hospitalized patients with essential hypertension. According to Sullivan's standard, 22 of the 53 patients were salt-sensitive (SS), 31 were salt-resistant (SR). The blood pressure in two groups of patients response to salt restriction diet were compared. The results showed that the decrease in level of blood pressure in SS group was higher than that in SR group after salt restriction diet (SS, 23.2 +/- 1.9/14.0 +/- 1.4 vs 21.4 +/- 1.7/13.1 +/- 1.3kPa, P < 0.01-0.05; SR, 23.4 +/- 2.0/14.1 +/- 1.4 vs 23.1 +/- 1.8/13.8 +/- 1.4kPa, P > 0.05). It was concluded that salt restriction diet was stressed on SS than SR patients.

The glossy1 locus of maize and an epidermis-specific cDNA from Kleinia odora define a class of receptor-like proteins required for the normal accumulation of cuticular waxes

Mutations at the glossy1 (gl1) locus of maize (Zea mays L.) quantitatively and qualitatively affect the deposition of cuticular waxes on the surface of seedling leaves. The gl1 locus has been molecularly cloned by transposon tagging with the Mutator transposon system. The epi23 cDNA was isolated by subtractive hybridization as an epidermis-specific mRNA from Senecio odora (Kleinia odora). The deduced amino acid sequence of the GL1 and EPI23 proteins are very similar to each other and to two other plant proteins in which the sequences were deduced from their respective mRNAs. These are the Arabidopsis CER1 protein, which is involved in cuticular wax deposition on siliques, stems, and leaves of that plant, and the protein coded by the rice expressed sequence tag RICS2751A. All four proteins are predicted to be localized in a membrane via a common NH2-terminal domain, which consists of either five or seven membrane-spanning helices. The COOH-terminal portion of each of these proteins, although less conserved, is predicted to be a water-soluble, globular domain. These sequence similarities indicate that these plant orthologs may belong to a superfamily of membrane-bound receptors that have been extensively characterized from animals, including the HIV co-receptor fusin (also termed CXCR4).

Mitogenic signaling mediated by oxidants in Ras-transformed fibroblasts

NIH 3T3 fibroblasts stably transformed with a constitutively active isoform of p21(Ras), H-RasV12 (v-H-Ras or EJ-Ras), produced large amounts of the reactive oxygen species superoxide (.O2-). .O2- production was suppressed by the expression of dominant negative isoforms of Ras or Rac1, as well as by treatment with a farnesyltransferase inhibitor or with diphenylene iodonium, a flavoprotein inhibitor. The mitogenic activity of cells expressing H-RasV12 was inhibited by treatment with the chemical antioxidant N-acetyl-L-cysteine. Mitogen-activated protein kinase (MAPK) activity was decreased and c-Jun N-terminal kinase (JNK) was not activated in H-RasV12-transformed cells. Thus, H-RasV12-induced transformation can lead to the production of .O2- through one or more pathways involving a flavoprotein and Rac1. The implication of a reactive oxygen species, probably .O2-, as a mediator of Ras-induced cell cycle progression independent of MAPK and JNK suggests a possible mechanism for the effects of antioxidants against Ras-induced cellular transformation.

[Threshold values of salt in instruction of salt-restricted diet for patients with heart disease]

The low-salt diet was basic means for therapeutic heart diseases. The salt threshold value represented individual's degree of salt taking or dietetic habit. The salt threshold value was measured in 60 patients with essential hypertension, 60 patients with congestive heart failure and 40 normal subjects. The salt threshold value revealed no significant difference in three groups (4.3% +/- 1.6%, 4.0% +/- 1.3% and 4.1% +/- 1.4%, P > 0.05). According to the salt threshold value, 120 patients were classed into three groups: high, middle and low salt threshold value group (n1 = 36, n2 = 74, n3 = 10). The patients were given selective and unitary low-salt diet with random before and after respectively. The results showed that acceptable level of patients to the diet in selective condition was significantly higher than that in unitary condition (81.7% vs 70.8%, P < 0.05). In conclusion, individualized selectivity restriction salt according to salt threshold value had advantage of no reducing appetite, patient's acceptance with ease and cooperative treatments.

Suppression of cAMP formation by adenosine in myenteric ganglia from guinea-pig small intestine

Effects of the adenosine receptor agonist 2-chloro-N6-cyclopentyl-adenosine (CCPA) on stimulation of cAMP formation by histamine, 5-hydroxytryptamine, substance P and forskolin were determined for enzymatically dissociated ganglia from the myenteric plexus of guinea-pig small intestine. Each of the 4 substances stimulated cAMP production. CCPA blocked the stimulation of cAMP by histamine, but not by 5-hydroxytryptamine or substance P. CCPA marginally suppressed stimulation by forskolin. CCPA alone suppressed basal levels of cAMP. The adenosine receptor antagonist 8-cyclopentyl-1,3-dimethylxanthine (CPT) reversed the inhibitory action of CCPA on stimulation of cAMP formation by histamine. Exposure to adenosine deaminase or CPT increased cAMP in the ganglia. The results are consistent with a hypothesis that stimulation of adenylate cyclase and elevation of intraneuronal cAMP in enteric neurons are steps in the signal transduction cascade for the excitatory actions of 5-hydroxytryptamine, substance P and histamine. They are consistent also with an original hypothesis from electrophysiologic studies which states that stimulation of adenosine A1 receptors suppresses cAMP formation and thereby slow synaptic excitation in response to histamine, but not to 5-hydroxytryptamine or substance P. The results support evidence from intracellular microelectrode studies which suggested that endogenous adenosine accumulates to levels sufficient for tonic suppression of cAMP formation in myenteric ganglia in vitro.

Measurement of myeloperoxidase in leukocyte-containing tissues

An improved method is reported for measurement of myeloperoxidase (MPO) activity in tissues. While spectrophotometric methods based on oxidation of O-dianisidine or other dyes have been reported for MPO measurement in pure polymorphonuclear leukocytes (PMNs), these methods often fail to accurately assay MPO activity in tissues. We observe that tissue myoglobin or vascular hemoglobin markedly effects the spectrophotometric assay for MPO. Under optimal conditions of 0.53 mM O-dianisidine, 0.15 mM H2O2, pH 6.0, either myoglobin or hemoglobin produced absorbance at 460 nm in a concentration-dependent manner similar to that of MPO. In perfused heart tissue, myoglobin caused a major problem with the assay resulting in an inability to obtain accurate linear results as a function of MPO concentration and PMN number. To eliminate the effect of tissue myoglobin or vascular hemoglobin on the assay, one-step gel filtration chromatography of tissue extracts was introduced. MPO, myoglobin, and hemoglobin were easily separated using a Sephadex G-75 column according to the difference in their molecular weights. A linear relationship between the MPO activity and PMN number was observed only after processing the tissue extracts through the Sephadex G-75 column. Thus, MPO activity in PMN-containing tissues can be precisely quantitated after one-step purification on a molecular exclusion column. Enzyme purification with removal of myoglobin is essential for obtaining accurate measurement of MPO activity and quantitation of PMNs in muscle tissue.

Genetic evidence for the involvement of tau in progressive supranuclear palsy

A dinucleotide repeat polymorphism in a tau intron was identified and used in a case-control study to analyze the genetic association of tau with several neurodegenerative diseases with tau pathology. Subjects with the homozygous tau AO alleles were excessively represented in the progressive supranuclear palsy (PSP) group, compared with the age-matched healthy control group. Consequently, this allele is more frequently found in PSP than in a group of healthy subjects. This trend was not found in Alzheimer's disease or parkinsonism-dementia complex of Guam, both of which are accompanied by major tau pathology. The result suggests a possible involvement of tau in the pathogenesis of PSP.

Postnatal expression of melanocortin-3 receptor in rat diencephalon and mesencephalon

In situ hybridization was applied to examine the postnatal expression of melanocortin-3 (MC-3) receptor mRNA in the rat brain. Very weak and limited signals were seen in the hypothalamus on postnatal day 0 (P0) and in the dorsal lateral thalamus on P4. A marked increase was noted in several regions of the diencephalon and mesencephalon on P7. The highest levels were reached on P21, which was the time when an adult-like pattern was established. On P21, intense signals were seen in the ventromedial nucleus and the arcuate nucleus of the tuberal hypothalamus, the habenular nucleus of the epithalamus and the ventral tegmental area. [125I] Nle4, D-Phe7-alpha-MSH showed overlapping, but wider labelling of melanocortin receptors, that followed a similar developmental course. alpha-MSH-like immunoreactivity was seen widely in the forebrain and midbrain from P14. In contrast to the staining of alpha-MSH in neurons and their process, gamma 2-MSH-like immunoreactivity was detected strongly in the blood vessels. The neuronal localization of MC-3 receptor mRNA suggests that this receptor may mediate the neurotropic actions of melanocortin peptides in the developing brain.

Modulations of breast fibroblast and carcinoma cell interactions by a dextran derivative (CMDB7)

Modulation of interactions between human breast carcinoma cells (MCF-7ras) and fibroblasts from normal breast tissue (MG3) and from a post-radiation fibrosis with recurrent breast carcinoma (FPR7) by a dextran derivative (CMDB7) was investigated. In a coculture system, MCF-7ras proliferation was increased (50%) by fibroblasts, and fibroblasts showed a 84% growth increase with MCF-7ras. This co-stimulation did not depend on fibroblast origin. CMDB7 can inhibit the growth of MCF-7ras but not the growth of fibroblasts. The addition of CMDB7 blocks the MCF-7ras stimulation by fibroblasts but not the fibroblast stimulation by MCF-7ras. Fibroblast-Conditioned Medium stimulated over 2-3 fold MCF-7ras's DNA synthesis but CMDB7 did not influence this paracrine stimulation. IGFI, IGFII stimulated MCF-7ras's DNA synthesis whereas bFGF inhibited it. CMDB7 did not block IGFI and IGFII's stimulatory effects but increased bFGF's inhibitory effects. These results indicate that CMDB7 can inhibit fibroblast-breast cancer cell interactions possibly by interfering with paracrine growth factor loops.

[The effects of He-Ne laser on the revascularization of the distal part of the subdermal vascular network skin flap]

The distal part of the subdermal vascular network (SVN) random skin flap on the rabbit was radiated with He-Ne laser at an energy density of 3.15 J/cm2. The blood vessels of the flap were perfused with Chinese ink. Histological examinations and image analysis were applied to evaluate the effects of He-Ne laser radiation on the SVN skin flap. It was found that the revascularization and the survival rate of the SVN random skin flap were highly related with the proportion of the length to width of the flap in the early stage. The radiation of the He-Ne laser could improve the microcirculation of the flap and increase its survival rate, which was mainly resulted from dilation of the blood vessels, especially the veins, and anastomosis of the vessels between the flap and the recipient site.

Neural network for solving extended linear programming problems

A neural network for solving extended linear programming problems is presented and is shown to be globally convergent to exact solutions. The proposed neural network only uses simple hardware in which no analog multiplier for variables is required, and has no parameter tuning problem. Finally, an application of the neural network to the L(1 )-norm minimization problem is given.

Identification of two rat genes orthologous to the human interleukin-8 receptors

The genes encoding two functional human interleukin-8 (IL-8) receptors have been identified by molecular cloning techniques and they are members of the rhodopsin G-protein coupled receptor (GCR) superfamily. We report the molecular cloning of two rat GCR genes (rat CXCR1-like and rat CXCR2) whose conceptualized amino acid sequences are approximately 70% identical to the human IL-8 A and B receptor subtypes. The murine GRO-like peptide, macrophage inflammatory peptide-2 (MIP-2), elevates intracellular calcium levels in HEK293 cells expressing the rat CXCR2 receptor. Southern blot analysis of restriction-digested rodent and human genomic DNAs indicate that rat CXCR1-like and CXCR2 are: 1) each single copy genes in the rat genome; 2) most closely related to the human IL-8 receptor genes; and 3) orthologous to two previously identified murine genes. CXCR2 mRNA is detected in adult rat lung, spleen, and neutrophils. CXCR1-like mRNA can be detected in adult rat lung, native rat macrophages, and a rat alveolar macrophage cell line (NR8383). These data identify the rat orthologs of the human IL-8 receptors, and describe cellular and tissue targets of rat C-X-C chemokine peptides.

Stimulation of formation of adenosine 3',5'-phosphate by histamine in myenteric ganglia isolated from guinea-pig small intestine

Effects of histamine and related agonists and antagonists on formation of cAMP were determined for enzymatically dissociated ganglia from the myenteric plexus of the guinea-pig small intestine. Formation of cAMP was stimulated by histamine in both dose- and time-dependent manners. The stimulatory action of histamine was suppressed by the histamine H2 receptor antagonist, cimetidine. The histamine H1 receptor antagonists, tripelennamine or pyrilamine also suppressed the stimulatory action of histamine, but only at concentrations 3-4 orders higher than required for cimetidine. Formation of cAMP was stimulated dose-dependently by the histamine H2 receptor agonist, dimaprit. The histamine H1 receptor agonist, 2-methyl-histamine, also stimulated cAMP production, but required a threshold concentration 4-5 orders higher than dimaprit. We conclude that histamine acts at the histamine H2 receptor subtype to stimulate adenylate cyclase and the formation of cAMP in myenteric ganglia of the guinea-pig small bowel.

Molecular modeling and design of invariant chain peptides with altered dissociation kinetics from class II MHC

We have used molecular modeling to design substitutions in an invariant chain-derived peptide (CLIP), so as to alter the stability of its complex with class II major histocompatibility complex (MHC) proteins. We sought first to test whether CLIP binds in the same way to different class II MHC proteins. We designed destabilizing substitutions of two residues (Met 91 and Met 99) previously predicted to act as the major anchor residues for binding to all class II MHC and measured their effect on CLIP's dissociation rate from a series of three murine I-A MHC proteins. Even a conservative substitution preserving size and hydrophobicity but reducing flexibility (leucine, a branched residue) caused large accelerations in dissociation rates (up to 25-fold) at either position in all three MHC alleles, supporting the consistent role of these positions as the major anchors for MHC binding. These data also support the view that the special flexibility of the methionine side chains at these positions is essential for binding to diverse MHC molecules. We also used molecular modeling to design allele-specific enhancements of peptide binding. Designed substitutions of CLIP Pro 96 by Ala (for Ad), Glu (Ak), and Tyr (Au) each yielded strong enhancement of binding (up to 128-fold) for their targeted allele and only moderate or destabilizing effects to the other alleles. These results demonstrate the accuracy of the molecular models and the predictive value of this modeling. Moreover, they provide strong evidence for the proposed general model of invariant chain association, indicating that it binds to all class II MHC in the same conformation.

Localization of ACTH receptor mRNA by in situ hybridization in mouse adrenal gland

Stimulation of steroidogenesis in the adrenal cortex is a major physiological action of adrenocorticotropic hormone (ACTH). This action is presumed to be mediated by the ACTH receptor and is functionally connected with the hypothalamus-pituitary-adrenal axis. To gain information concerning the distribution of the ACTH receptor in this axis, we examined mRNA for the ACTH receptor in the adrenal gland, pituitary and hypothalamus of the mouse, by using in situ hybridization. The Y-1 mouse adrenal tumour cell line was also examined. The specific hybridization signal for ACTH receptor mRNA was uniformly distributed in the Y-1 cells, although the level of expression was low. The adrenal cortex showed a strong signal for the ACTH receptor mRNA in both the zona fasciculata and the zona glomerulosa, sites that are involved in the mediation of the action of ACTH on the synthesis and release of glucocorticoids and aldosterone. In the zona reticularis of the cortex, a small number of cells showed positive hybridization signals. Moreover, a few scattered cells were positive in the adrenal medulla. In contrast, the hybridization results for both the hypothalamus and the pituitary proved to be negative. These results indicate that the mouse ACTH receptor is a peripheral receptor that is exclusively located in the adrenal gland.

Controlling cell attachment on contoured surfaces with self-assembled monolayers of alkanethiolates on gold

This paper describes a method based on experimentally simple techniques--microcontact printing and micromolding in capillaries--to prepare tissue culture substrates in which both the topology and molecular structure of the interface can be controlled. The method combines optically transparent contoured surfaces with self-assembled monolayers (SAMs) of alkanethiolates on gold to control interfacial characteristics; these tailored interfaces, in turn, control the adsorption of proteins and the attachment of cells. The technique uses replica molding in poly(dimethylsiloxane) molds having micrometer-scale relief patterns on their surfaces to form a contoured film of polyurethane supported on a glass slide. Evaporation of a thin (< 12 nm) film of gold on this surface-contoured polyurethane provides an optically transparent substrate, on which SAMs of terminally functionalized alkanethiolates can be formed. In one procedure, a flat poly(dimethylsiloxane) stamp was used to form a SAM of hexadecanethiolate on the raised plateaus of the contoured surface by contact printing hexadecanethiol [HS(CH2)15CH3]; a SAM terminated in tri(ethylene glycol) groups was subsequently formed on the bare gold remaining in the grooves by immersing the substrate in a solution of a second alkanethiol [HS(CH2)11(OCH2CH2)3OH]. Then this patterned substrate was immersed in a solution of fibronectin, the protein adsorbed only on the methyl-terminated plateau regions of the substrate [the tri(ethylene glycol)-terminated regions resisted the adsorption of protein]; bovine capillary endothelial cells attached only on the regions that adsorbed fibronectin. A complementary procedure confined protein adsorption and cell attachment to the grooves in this substrate.

[Effects of clomiphene citrate treatment on endometrial estrogen and progesterone receptors expressions]

OBJECTIVE

To assess the effects of clomiphene citrate (CC) on estrogen receptors (ER) and progesterone receptors (PR) expressions in glandular, epithelial and stromal cells of endometrium.

METHODS

Endometrium samples of 16 normal ovulatory women (11 with unexplained and 5 female infertility) were taken in the late proliferative phase (12th day) and late secretory phase (10 days after ovulation), both in spontaneous and CC-induced cycles. ER and PR in glandular, epithelial and stromal cells of endometrium were localized and their histological score (H-score) were measured semi-quantitatively by monoclonal antibodies immunohistochemical analysis.

RESULTS

The H-score of ER and PR contents were significantly lower in late proliferative phase and secretory phase of CC cycles when compared with that in spontaneous cycles (P < 0.01, P < 0.05). The decrease of receptor contents in glandular cells was significantly pronounced than that in stromal cells (P < 0.05). In late proliferative phase the decrease of ER was significantly severe than that of PR. On the contrary in late secretory phase the decline of PR was more significant.

CONCLUSIONS

Based on these data, we suggested that CC inhibited the ER and PR induction in endometrium and affected endometrial development. These may be one of the causes of low pregnancy rate in CC-induced cycles.

Actions of Daiichi DQ-2511 on electrical and synaptic behavior of enteric neurons in the guinea-pig small intestine

Intracellular recording of electrical and synaptic behavior of neurons in the enteric nervous system of guinea-pig small intestine was used to evaluate actions of DQ-2511 (3-[[[2-(3, 4-dimethoxyphenyl)ethyl]carbamoyl]methyl]amino-N-methylbenzamide). DQ-2511 is a new drug with gastrointestinal prokinetic action. DQ-2511 was most effective in the nanomolar range. The drug depolarized some of the neurons and this was accompanied by increased input resistance and augmented excitability. DQ-2511 in nanomolar concentrations increased the amplitude of fast excitatory postsynaptic potentials at nicotinic synapses. Slow inhibitory postsynaptic potentials, produced by release of norepinephrine from sympathetic postganglionic fibers, were suppressed by DQ-2511. This appeared to reflect presynaptic suppression of release of norepinephrine because postsynaptic responses to exogenously applied norepinephrine were unaffected. The results suggest that the prokinetic action of DQ-2511 on gastrointestinal transit might emerge from actions that augment excitatory synaptic transmission in the microcircuits of the enteric nervous system while suppressing inhibitory sympathetic neurotransmission.

ApoE and CYP2D6 polymorphism with and without parkinsonism-dementia complex in the people of Chamorro, guam

Parkinsonism-dementia complex (PDC), a neurodegenerative disorder in the Chamorro, Guam population, has been epidemiologically ascribed to the ingestion of the neurotoxin cycasin. This disease is characterized neuropathologically by the presence of abundant neurofibrillary tangles (NFTs). We analyzed a genetic risk factor of Alzheimer's disease (AD), apolipoprotein E, hypothesized to be linked to NFT formation, and a genetic risk factor of Parkinson's disease (PD), CYP2D6 mutation, linked to slower metabolism of exogenous toxins, in Chamorro, Guam individuals with and without PDC. The representation of the G-to-C mutation in exon 9 of the CYP2D6 gene was higher in Chamorro and Filipino than in Caucasian individuals, but this mutant allele had similar high frequencies in both PDC patients and healthy Chamorro individuals. We found no alleles of these genes associated with AD or PD to be overrepresented among those with PDC.

Genetic studies in Alzheimer's disease with an NACP/alpha-synuclein polymorphism

The non-Abeta component of Alzheimer's disease amyloid (NAC) is copurified with amyloid from the brain tissue of Alzheimer's disease victims and is immunohistochemically localized to amyloid fibrils. NAC is a hydrophobic peptide fragment from the NAC precursor protein (NACP/alpha-synuclein) that is localized to presynaptic terminals. We used a polymorphic dinucleotide repeat sequence in a genomic clone of NACP for genetic association and linkage studies. Screening of Alzheimer's disease families failed to establish linkage between NACP and Alzheimer's disease. Nevertheless, one of the NACP polymorphisms (NACP allele 2) was shown to have significant association with healthy elderly control individuals with apolipoprotein E risk. This may indicate a possible protective function of the allele.

Ductal cyst formation in collagen-embedded adult human islet preparations. A means to the reproduction of nesidioblastosis in vitro

Neogenesis of endocrine islets from ductal epithelium termed nesidioblastosis has been described in vivo after various experimental conditions (90% pancreatectomy or pancreas wrapping in the rodent) and in clinical pathologies. In the adult regenerating pancreas, a proliferation and organization of ductal epithelium into tubular structures precedes its differentiation into endocrine cells. Reproduction of nesidioblastosis in vitro may provide a novel approach to human islet propagation in vitro. With this aim, adult human islet preparations were cultured in diverse three-dimensional (3D) gels in the presence of serum. After 3-5 days in rat tail collagen gels, proliferating (bromodeoxyuridine-positive) cystic structures appeared associated with islets and as isolated spheres. Percentage labeling indexes of the cysts were 4.1, 18.7, 15.4, and 13.3% after 3, 5, 7, and 10 days of culture, respectively. Immunohistochemistry confirmed the ductal (carbohydrate antigen 19-9) and epithelial (keratin-1) nature of the cysts. No cysts were formed in agarose gels or Vitrogen 100, whereas the cyst number was increased by the quantity of serum (20% > 10%) and gels rich in extracellular matrix components and growth factors (Matrigel). The latter lead to tubular networks. Single endocrine islet cells were observed in the ductal cysts after 7 (2.8%) to 10 (5.6%) days in rat tail collagen. Our observations paralleled the changes characteristic of the regenerating pancreas in vivo. 3D culture may permit the identification of matrix and media constituents promoting the neogenesis of islets and may be the means to increase the mass of endocrine tissue obtained from adult cadaveric pancreases for transplantation.

[Expression of p53 gene in oral squamous cell carcinoma and its relations with clinical and pathological parameters and prognosis of patients]

One hundred and eleven cases of oral squamous cell carcinoma (OSCC) were examined for overexpression of p53 protein by using immunohistochemical technique. Association of p53 protein overexpression with clinical and pathological parameters as well as prognosis of patients were also analyzed, p53 protein overexpression was commonly observed (69.4%) in the OSCC patients and might be used as a marker of carcinogenesis of OSCC. The level of p53 protein overexpression was correlated with the decreased three and/or five-year survival rate of OSCC. The presence of p53 was not correlated with patient's sex and age, site and size of tumor, degree of differentiation, node status or clinical stage of OSCC. Single factor COX proportional hazards regression model analysis indicated that there was no significant relationship between p53 overexpression and prognosis of OSCC. Multivariable COX model analysis failed to establish effective life function or risk rate function. This showed that all the parameters analyzed in this study as well as p53 overexpression were not significant or effective risk factors to predict prognosis of OSCC patients.

Cloning and characterization of CER2, an Arabidopsis gene that affects cuticular wax accumulation

Cuticular waxes are complex mixtures of very long chain fatty acids and their derivatives that cover plant surfaces. Mutants of the ECERIFERUM2 (cer2) gene of Arabidopsis condition bright green stems and siliques, indicative of the relatively low abundance of the cuticular wax crystals that comprise the wax bloom on wild-type plants. We cloned the CER2 gene via chromosome walking. Three lines of evidence establish that the cloned sequence represents the CER2 gene: (1) this sequence is capable of complementing the cer2 mutant phenotype in transgenic plants; (2) the corresponding DNA sequence isolated from plants homozygous for the cer2-2 mutant allele contains a sequence polymorphism that generates a premature stop codon; and (3) the deduced CER2 protein sequence exhibits sequence similarity to that of a maize gene (glossy2) that also is involved in cuticular wax accumulation. The CER2 gene encodes a novel protein with a predicted mass of 47 kD. We studied the expression pattern of the CER2 gene by in situ hybridization and analysis of transgenic Arabidopsis plants carrying a CER2-beta-glucuronidase gene fusion that includes 1.0 kb immediately upstream of CER2 and 0.2 kb of CER2 coding sequences. These studies demonstrate that the CER2 gene is expressed in an organ- and tissue-specific manner; CER2 is expressed at high levels only in the epidermis of young siliques and stems. This finding is consistent with the visible phenotype associated with mutants of the CER2 gene. Hence, the 1.2-kb fragment of the CER2 gene used to construct the CER2-beta-glucuronidase gene fusion includes all of the genetic information required for the epidermis-specific accumulation of CER2 mRNA.

Complex Optical Surfaces Formed by Replica Molding Against Elastomeric Masters

Complex, optically functional surfaces in organic polymers can be fabricated by replicating relief structures present on the surface of an elastomeric master with an ultraviolet or thermally curable organic polymer, while the master is deformed by compression, bending, or stretching. The versatility of this procedure for fabricating surfaces with complex, micrometer- and submicrometer-scale patterns was demonstrated by the production of (i) diffraction gratings with periods smaller than the original grating; (ii) chirped, blazed diffraction gratings (where the period of a chirped grating changes continuously with position) on planar and curved surfaces; (iii) patterned microfeatures on the surfaces of approximately hemispherical objects (for example, an optical surface similar to a fly's eye); and (iv) arrays of rhombic microlenses. These topologically complex, micropatterned surfaces are difficult to fabricate with other techniques.

Nitric oxide synthase generates superoxide and nitric oxide in arginine-depleted cells leading to peroxynitrite-mediated cellular injury

Besides synthesizing nitric oxide (NO), purified neuronal NO synthase (nNOS) can produce superoxide (.O2-) at lower L-Arg concentrations. By using electron paramagnetic resonance spin-trapping techniques, we monitored NO and .O2- formation in nNOS-transfected human kidney 293 cells. In control transfected cells, the Ca2+ ionophore A23187 triggered NO generation but no .O2- was seen. With cells in L-Arg-free medium, we observed .O2- formation that increased as the cytosolic L-Arg levels decreased, while NO generation declined. .O2- formation was virtually abolished by the specific NOS blocker, N-nitro-L-arginine methyl ester (L-NAME). Nitrotyrosine, a specific nitration product of peroxynitrite, accumulated in L-Arg-depleted cells but not in control cells. Activation by A23187 was cytotoxic to L-Arg-depleted, but not to control cells, with marked lactate dehydrogenase release. The cytotoxicity was largely prevented by either superoxide dismutase or L-NAME. Thus, with reduced L-Arg availability NOS elicits cytotoxicity by generating .O2- and NO that interact to form the potent oxidant peroxynitrite. Regulating arginine levels may provide a therapeutic approach to disorders involving .O2-/NO-mediated cellular injury.

Swelling and Ca2+-activated anion conductances in C127 epithelial cells expressing WT and delta F508-CFTR

CFTR is a chloride channel that is required for fluid secretion and salt absorption in many exocrine epithelia. Mutations in CFTR cause cystic fibrosis. CFTR expression influences some ion channels, but the range of channels influenced, the mechanism of the interaction and the significance for cystic fibrosis are not known. Possible interactions between CFTR and other ion channels were studied in C127 mouse mammary epithelial cell lines stably transfected with CFTR, delta F508-CFTR, or vector. Cell lines were compared quantitatively using an 125I efflux assay and qualitatively using whole-cell patch-clamp recording. As expected, 125I efflux was significantly increased by forskolin only in the CFTR line, and forskolin-stimulated whole-cell currents were time- and voltage independent. All three lines responded to hypotonic challenge with large 125I efflux responses of equivalent magnitude, and whole-cell currents were outwardly rectified and inactivated at positive voltages. Unexpectedly, basal 125I efflux was significantly smaller in the delta F508-CFTR cell line than in either the CFTR or control cell lines (P < 0.0001), and the magnitude of the efflux response to ionomycin was largest in the vector cell line and smallest in the cell line expressing delta F508-CFTR (P < 0.01). Whole-cell responses to ionomycin had a linear instantaneous I-V relation and activated at depolarizing voltages. Forskolin responses showed simple summation with responses to ionomycin or hypotonic challenge. Thus, we found no evidence for interactions between CFTR and the channels responsible for swelling-mediated responses. Differences were found in basal and ionomycin-stimulated efflux, but these may arise from variations in the clonally selected cell lines that are unrelated to CFTR expression.

Antigen compartmentation and T helper cell tolerance induction

The process of antigen recognition depends in part on the amount of peptide antigen available and the affinity of the T cell receptor for a particular peptide-major histocompatibility complex (MHC) molecule complex. The availability of self antigen is limited by antigen processing, which is compartmentalized such that peptide antigens presented by MHC class I molecules originate in the cytoplasm, whereas peptide antigens presented by MHC class II molecules are acquired from the endocytic pathway. This segregation of the antigen-processing pathways may limit the diversity of antigens that influence the development and selection of, e.g., CD4-positive, MHC class II-specific T cells. Selection in this case might involve only a subset of self-encoded proteins, specifically those that are plasma membrane bound or secreted. To study these aspects of immune development, we engineered pigeon cytochrome for expression in transgenic mice in two forms: one in which it was expressed as a type II plasma membrane protein, and a second in which it was targeted to the mitochondria after cytoplasmic synthesis. Experiments with these mice clearly show that tolerance is induced in the thymus, irrespective of antigen compartmentation. Using radiation bone marrow chimeras, we further show that cytoplasmic/mitochondrial antigen gains access to the MHC class II pathway by direct presentation. As a result of studying the anatomy of the thymus, we show that the amount of antigen and the affinity of the TCR affect the location and time point of thymocytes under-going apoptosis.

Change in expression of heart carnitine palmitoyltransferase I isoforms with electrical stimulation of cultured rat neonatal cardiac myocytes

Electrical stimulation of neonatal rat cardiac myocytes in culture produces increases in myocyte size (hypertrophy) and organization of actin into myofibrillar arrays. The maturation of the cells is associated with enhanced contractile parameters and cellular calcium content. The numbers and intensity of cellular mitochondrial profiles increase, as measured by scanning laser confocal microscopy. Consistent with the hypertrophic response is increased cellular content of beta-myosin heavy chain and cytochrome oxidase subunit Va messages, as well as increases in cytochrome oxidase activity in the stimulated cardiac myocytes. Myocyte contractile capacity is associated with increased expression of the muscle carnitine palmitoyltransferase (CPT-I) isoform as measured by Northern analysis, immunoblotting, and altered sensitivity of CPT-I activity to malonyl-CoA in the stimulated cells. The data suggest that a switch from the liver isoform of CPT-I, prominent in the neonatal rat heart, to the muscle CPT-I which predominates in adult rat heart, takes place in the neonatal cardiac myocytes over the same time period as the hypertrophic-mediated changes in myofibrillar assembly and increased contractile activity.

Delta F508-CFTR channels: kinetics, activation by forskolin, and potentiation by xanthines

Trafficking, activation, and kinetics of delta F508-cystic fibrosis transmembrane conductance regulator (CFTR) and CFTR were compared in stably transduced C127I mouse mammary epithelial cells. Western blots detected a small amount of fully glycosylated delta F508-CFTR Efflux of 125I was stimulated by forskolin with the same mean effective concentration (EC50; approximately 0.5 microM) for CFTR and delta F508-CFTR cells, but the maximum response was reduced more than fivefold and its latency increased approximately threefold in delta F508-CFTR cells. In delta F508-CFTR cells, 3-isobutyl-1-methylxanthine (IBMX; EC50 = 1.45 microM) and 8-cyclopentyl-1,3-dipropylxanthine (CPX; EC50 = 58 microM) increased the peak forskolin-stimulated efflux rate approximately 2.5-fold and decreased the time to peak. A sevenfold increase in intracellular adenosine 3',5'-cyclic monophosphate (cAMP) levels accompanied potentiation of forskolin-induced 125I efflux by IBMX but not by CPX. Elevation of intracellular cAMP increased linear voltage-independent whole cell currents 30-fold in CFTR and 4-fold in delta F508-CFTR cells; the response rate in delta F508-CFTR cells was much slower. Single-channel currents were detected in 57 of 68 cell-attached patches from forskolin-prestimulated CFTR cells vs. 6 of 35 patches in delta F508-CFTR cells. Mean number of active channels per patch was 4.1 for CFTR [open probability (Po) = 0.34] and 0.2 for delta F508-CFTR (Po = 0.11). The lower Po of delta F508-CFTR resulted from an approximately threefold longer mean interburst interval. We estimate that forskolin-stimulated chloride conductance of delta F508-CFTR C127I cells is < 5% of CFTR cells. CPX is approximately 25-fold more potent than IBMX in potentiating delta F508-CFTR and may operate by a mechanism other than elevation of cAMP.

Swelling and fibronectin accumulation in articular cartilage explants after cyclical impact

The objective of this study was to determine if repeated impact could damage living cartilage and lead to osteoarthritis-like changes in its biology. Canine cartilage explants were subjected to impacts of as much as 50 MPa once every 5 seconds for 30 minutes. On each impact cycle, the loading rate was 100 MPa/sec to the assigned peak stress, which was held for 1 second. After impact testing, the cartilage was kept in defined culture for as long as 10 days. Radiosulfate incorporation in the region that received direct impact varied with load 0-4 hours after impact, but it did not vary with load at 20-24 hours after impact. Even so, most explants were visibly damaged by 20 or 50 MPa, and there was subtle evidence of damage from impacts of 5 or 10 MPa. For example, ion-induced swelling in 0.01 M NaCl was increased, suggesting that the physical integrity of the matrix was reduced relative to controls. Self-diffusion of water, measured by proton magnetic resonance imaging was also increased in the deeper zones of the explant, consistent with changes in structure at the molecular level. Ten days after impact, the water content and the fibronectin content of the loaded region of the explant were both increased. In combination, these osteoarthritis-like changes suggested that the physical strength of normal cartilage limits its ability to withstand cyclical impact.

Adenosine deaminase inhibition prevents free radical-mediated injury in the postischemic heart

In the presence of its substrates hypoxanthine and xanthine, xanthine oxidase generates oxygen free radicals that cause postischemic injury. Recently, it has been demonstrated that the burst of xanthine oxidase-mediated free radical generation in the reperfused heart is triggered by a large increase in substrate formation, which occurs secondary to the degradation of adenine nucleotides during ischemia. It is not known, however, whether blocking this substrate formation is sufficient to prevent radical generation and functional injury. Therefore, studies were performed in isolated rat hearts in which xanthine oxidase substrate formation was blocked with the adenosine deaminase inhibitor erythro-9-(2-hydroxy-3-nonyl)adenine (EHNA), and measurements of contractile function and free radical generation were performed. Chromatographic measurements of the intracellular adenine nucleotide pool showed that preischemic administration of EHNA blocked postischemic hypoxanthine, xanthine, and inosine formation. Electron paramagnetic resonance spin trapping measurements of free radical generation showed that inhibition of adenosine deaminase with EHNA blocked free radical generation and that it also increased the recovery of contractile function by more than 2-fold. Exogenous infusion of hypoxanthine and xanthine totally reversed the protective effects of EHNA. These results demonstrate that blockade of xanthine oxidase substrate formation by adenosine deaminase inhibition can prevent free radical generation and contractile dysfunction in the postischemic heart.

[Addison's disease in pregnancy: a report of six cases]

OBJECTIVE

To review six cases of pregnancy with Addison's disease at Obstetrics and Gynecology Hospital, Shanghai Medical University from 1949 to 1994.

METHOD

This is a clinical retrospective analysis. Five of the 6 patients were treated with hormone replacement therapy, and the remaining one received no hormone treatment due to lack of symptoms during pregnancy and neglect of previous adrenal surgery by obstetricians.

RESULTS

The patient received no treatment occurred Addisonian crisis and died soon after delivery. The other five patients had smooth course of delivery and postpartum period.

CONCLUSIONS

Hormone replacement therapy is important for patients with Addison's disease in pregnancy especially for acute decompensation of adrenal function. Pregnant women with history of adrenal surgery should be monitored carefully even without any symptoms and hormone treatment is necessary. Vaginal delivery is encouraged unless there is obstetric indication.

Cloning of rat 92-kDa type IV collagenase and expression of an active recombinant catalytic domain

A full-length cDNA for rat 92-kDa type IV collagenase was isolated and sequenced. RNase protection assay revealed tissue specific differential expression of the 92-kDa type IV collagenase in the rat during development. Natural and modified forms of the 92-kDa type IV collagenase were expressed. One active protein, 92-CD, contained only the putative catalytic domain. Large quantities of the 92-CD were expressed in Escherichia coli, extracted from inclusion bodies, purified, and refolded to an active form. This recombinant protein was able to cleave denatured and native collagen and was inactivated by known MMP inhibitors.

Metabolism of subtoxic levels of selenium in animals and humans

Since high levels of selenium are used as cancer chemopreventive agents in animals and humans, a better understanding of the metabolism of subtoxic levels is desirable. Absorption from rat small intestine using in situ double perfusion, ligated intestinal segments, and brush border membrane vesicles (BBMV) was used to study selenium absorption. A level of 1.2 mM intraluminal selenite was required to inhibit 50 percent of the transepithelial transport of 3-0-methylglucose, indicating a high tolerance of the intestinal tract to selenium. The relative efficiency patterns for uptake of different selenocompounds during in vitro perfusion and in vivo ligated segments were identical with selenomethionine (SeMet) > selenate > selenite. In contrast, selenite was taken up most rapidly by BBMV, followed by SeMet and selenate in decreasing order. Ligated segments, double perfusion experiments, and uptake by BBMV indicated that selenium as selenodiglutathione or selenodicysteine was taken up faster than when present as selenite. Selenate and SeMet appeared in the vascular effluent largely unchanged, but selenite was metabolized extensively during absorption. Most of the selenium in plasma from subjects living in a high selenium area of China was associated with albumin, which is likely a result of high dietary intake of SeMet. Cracked fingernails and extensive hair loss were the symptoms of selenium toxicity in these individuals. Low adverse effect level of dietary (mean LOAEL) selenium was calculated to be about 1540 +/- 653 micrograms per day (or 28 micrograms/kg body weight) and the maximum safe dietary (mean NOAEL) selenium was calculated to be 819 +/- 126 micrograms per day (or 15 micrograms/kg body weight).

Anchorage mediated by integrin alpha6beta4 to laminin 5 (epiligrin) regulates tyrosine phosphorylation of a membrane-associated 80-kD protein

Detachment of basal keratinocytes from basement membrane signals a differentiation cascade. Two integrin receptors alpha6beta4 and alpha3beta1 mediate adhesion to laminin 5 (epiligrin), a major extracellular matrix protein in the basement membrane of epidermis. By establishing a low temperature adhesion system at 4 degrees C, we were able to examine the exclusive role of alpha6beta4 in adhesion of human foreskin keratinocyte (HFK) and the colon carcinoma cell LS123. We identified a novel 80-kD membrane-associated protein (p80) that is tyrosine phosphorylated in response to dissociation of alpha6beta4 from laminin 5. The specificity of p80 phosphorylation for laminin 5 and alpha6beta4 was illustrated by the lack of regulation of p80 phosphorylation on collagen, fibronectin, or poly-L-lysine surfaces. We showed that blocking of alpha3beta1 function using inhibitory mAbs, low temperature, or cytochalasin D diminished tyrosine phosphorylation of focal adhesion kinase but not p80 phosphorylation. Therefore, under our assay conditions, p80 phosphorylation is regulated by alpha6beta4, while motility via alpha3beta1 causes phosphorylation of focal adhesion kinase. Consistent with a linkage between p80 dephosphorylation and alpha6beta4 anchorage to laminin 5, we found that phosphatase inhibitor sodium vanadate, which blocked the p80 dephosphorylation, prevented the alpha6beta4-dependent cell anchorage to laminin 5 at 4degreesC. In contrast, adhesion at 37 degrees C via alpha3beta1 was unaffected. Furthermore, by in vitro kinase assay, we identified a kinase activity for p80 phosphorylation in suspended HFKs but not in attached cells. The kinase activity, alpha6beta4, and its associated adhesion structure stable anchoring contacts were all cofractionated in the Triton-insoluble cell fraction that lacks alpha3beta1. Thus, regulation of p80 phosphorylation, through the activities of p80 kinase and phosphatase, correlates with alpha6beta4-SAC anchorage to laminin 5 at 4 degrees C in epithelial cells of the skin and intestine. Transmembrane signaling through p80 is an early tyrosine phosphorylation event responsive to and possibly required for anchorage to laminin 5 by HFK and LS123 epithelial cells.

Immunological localisation of melanocortin 1 receptor on the cell surface of WM266-4 human melanoma cells

The localisation of melanocortin 1 receptor (MC1R) in WM266-4 human melanoma cells was investigated by applying an antipeptide antiserum specific for the cloned human MC1R (MSH receptor). In enzyme-linked immunosorbent assay (ELISA), the immunoreactivity was detected in the membrane fraction of WM266-4 cells. The ELISA reactivity could be inhibited by an antiserum pre-absorbed with its specific synthetic peptide. In immunocytochemistry, the specific immunoreactivity was demonstrated on the surface of the cells by using either biotin-avidin immunoalkaline phosphatase- or TRITC-staining method. These results indicate that the MC1R is prominently present on the plasma membrane of WM266-4 human melanoma cells.