A three-dimensional tissue culture model for the study of attach and efface lesion formation by enteropathogenic and enterohaemorrhagic Escherichia coli.

We sought to develop a practical and representative model to study the interactions of enteropathogenic and enterohaemorrhagic Escherichia coli (EPEC and EHEC, respectively) with human intestinal tissue. For this purpose, human intestinal epithelial HCT-8 cells were cultured under low-shear microgravity conditions in a rotating cell culture system. After 10 days, layered cell aggregates, or 'organoids', developed.

Proteomic analysis of rat atrial secretory granules: a platform for testable hypotheses.

The recent development of powerful proteomic tools has enabled investigators to directly examine the population of proteins present in defined biological systems. We report here the first proteomic analysis of atrial secretory granules. Approximately 100 distinct protein components of the atrial secretory granule proteome were detected using subcellular fractionation and one-dimensional SDS-PAGE in conjunction with peptide mass fingerprinting by MALDI-TOF mass spectrometry.

Mapping protein expression in mouse pancreatic islets by immunolabeling and electron energy loss spectrum-imaging.

A combination of immuno-electron microscopy and electron energy-loss spectrum-imaging was used to map the distributions of endocrine polypeptide hormones and proteins in mouse pancreatic islet of Langerhans. Tissue was analyzed from control animals and from mice that were heterozygous for the Anx7 gene, which defines a Ca2+/GTP-dependent membrane fusion and ion channel protein. The heterozygous Anx7 (+/-) mouse displays defects in IP3 receptor mediated Ca2+ signaling and insulin secretion.

Anx7 is required for nutritional control of gene expression in mouse pancreatic islets of Langerhans.

Background: Gene expression in islets of Langerhans is profoundly sensitive to glucose and other nutrients. Islets of Langerhans in the Anx7(+/-) knockout mouse exhibit a profound reduction in ITPR3 protein expression, defective intracellular calcium signaling, and defective insulin secretion. Additional data presented here also show that mRNA for ITPR3 is virtually undetectable in isolated Anx7(+/-) islets.

Influence of the Anx7 (+/-) knockout mutation and fasting stress on the genomics of the mouse adrenal gland.

The Anx7 gene codes for a Ca(2+)/GTPase with calcium channel and membrane fusion properties that has been proposed to regulate exocytotic secretion in chromaffin and other cell types. We have previously reported that the homozygous Anx7 (+/-) knockout mouse has an embryonically lethal phenotype. However, the viable heterozygous Anx7 (+/-) mouse displays a complex phenotype that includes adrenal gland hypertrophy, chromaffin cell hyperplasia, and defective IP(3) receptor (IP(3)R) expression.

Gliotoxin-induced cytotoxicity proceeds via apoptosis and is mediated by caspases and reactive oxygen species in LLC-PK1 cells.

Renal failure associated with aspergillosis is caused by pathogenic fungi. Gliotoxin is a toxic epipolythiodioxopiperazine metabolite produced by the pathogens. The present study investigated the cytotoxicity and underlying mechanisms induced by gliotoxin in LLC-PK1 cells, a porcine renal proximal tubular cell line.

Defects in inositol 1,4,5-trisphosphate receptor expression, Ca(2+) signaling, and insulin secretion in the anx7(+/-) knockout mouse.

The mammalian anx7 gene codes for a Ca(2+)-activated GTPase, which supports Ca(2+)/GTP-dependent secretion events and Ca(2+) channel activities in vitro and in vivo. To test whether anx7 might be involved in Ca(2+) signaling in secreting pancreatic beta cells, we knocked out the anx7 gene in the mouse and tested the insulin-secretory properties of the beta cells. The nullizygous anx7 (-/-) phenotype is lethal at embryonic day 10 because of cerebral hemorrhage.

Differential binding of proteins to peroxisomes in rat hepatoma cells: unique association of enzymes involved in isoprenoid metabolism.

Farnesyl diphosphate synthase (FPPS: EC2.5.1.

Detection of fragmented DNA in apoptotic cells embedded in LR white: A combined histochemical (LM) and ultrastructural (EM) study.

We developed an improved method for the detection of double-strand DNA breaks in apoptotic cells at both the light (LM) and electron microscopic (EM) levels using a modification of the TdT (terminal deoxynucleotidyl transferase)-mediated dUTP nick end-labeling (TUNEL) technique. Cultured rat cerebellar granule cells were exposed to low potassium conditions to induce apoptosis. Twenty-four hr after treatment, one group of cells was fixed in situ with 4% paraformaldehyde and labeled for DNA fragmentation characteristic of apoptosis.

Quinolinic acid protects rat cerebellar granule cells from glutamate-induced apoptosis.

The effects of quinolinic acid (QUIN) on glutamate-induced excitotoxicity were examined in primary cultures of rat cerebellar granule neurons. Exposing these neurons to QUIN (< or =2.5 mM) in the presence of glucose and Mg2+ had no effect on their viability.

A polarized salivary cell monolayer useful for studying transepithelial fluid movement in vitro.

There are no reported, convenient in vitro models for studying polarized functions in salivary epithelial cells. Accordingly, we examined three often-used salivary cell lines for their ability to form a polarized monolayer on permeable, collagen-coated polycarbonate filters. Only the SMIE line, derived from rat submandibular gland, had this ability.

Gliosis in the LP-BM5 murine leukemia virus-infected mouse: an animal model of retrovirus-induced dementia.

Mice infected with the LP-BM5 murine leukemia virus (MuLV) mixture develop severe immunosuppression, neurotransmitter abnormalities and cognitive impairments in the absence of significant viral or macrophage invasion of the CNS. The time-course of the changes in glial activation have been characterized in an effort to understand the cellular basis of the neurobehavioral abnormalities observed in these mice. Glial activation was determined by measuring the relative changes in F4/80 protein and GFAP immunoreactivity using immunoblots.

Detection and localization of synexin (Annexin VII) in Xenopus adult and embryonic tissues using an antibody to the Xenopus N-terminal PGQM repeat domain.

Synexin (Annexin VII) is a widely distributed member of the annexin gene family which forms calcium channels and drives calcium-dependent membrane fusion. In Xenopus laevis, different synexins contain two to six tandem repeats of the tetra amino acid sequence PGQM in the unique N-terminal, with a distribution specific to adult tissues and embryonic stages. Immunogold studies using the PGQM-specific polyclonal antibody showed that synexin is localized in adult muscle to myosin-rich A-bands, Z-bands, and T-tubules, and in other adult tissues to nuclei and mitochondria and other formed elements.

The MPTP-induced parkinsonian syndrome in the goldfish is associated with major cell destruction in the forebrain and subtle changes in the optic tectum.

The neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) can induce a parkinsonian syndrome in humans and nonhuman primates, which is susceptible to treatment and prevention by drugs such as L-DOPA and L-deprenyl. Recently, we have reported that MPTP can also cause a parkinsonian syndrome in the common goldfish, which appears to faithfully mirror the neurochemical and behavioral aspects of the action of MPTP in the higher vertebrates. In addition, we recently identified the likely teleost equivalent of the substantia nigra in the goldfish forebrain, the "nucleus pars medialis," on the basis of its destruction by MPTP and selective protection by the MAO-B blocker L-deprenyl.

Comparison of LR White and Unicryl as embedding media for light and electron immunomicroscopy of chromaffin cells.

LR White and Unicryl are members of the same family of acrylic embedding resins and are very suitable for "on grid" postembedding immunogold labeling. We studied the ultrastructure of LR White- and Unicryl-embedded cultured chromaffin cells and the immunolocalization of three chromaffin cell proteins, the enzymes dopamine-beta-hydroxylase (DbetaH) and tyrosine hydroxylase (TH), and the membrane fusion and Ca2+ channel protein synexin (annexin VII). We report here that Unicryl is preferable to LR White as an embedding medium for electron microscopy when osmium tetroxide fixation is omitted.

Effect of MPTP on dopaminergic neurons in the goldfish brain: a light and electron microscope study.

The neurotoxin MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine) causes a Parkinsonian syndrome in the goldfish (Carassius auratus), characterized by transient bradykinesia, the accumulation of MPP+ in the brain, and a decrease in the forebrain and midbrain content of catecholamines (Pollard et al., FASEB J., 6 (1992) 3108-3116).

Granule swelling in stimulated bovine adrenal chromaffin cells: regulation by internal granule pH.

Adrenal medullary chromaffin cells secrete catecholamines through exocytosis of their intracellular chromaffin granules. Osmotic granule swelling has been implicated to play a role in the generation of membrane stress associated with the fusion of the granule membrane. However, controversy exists as to whether swelling occurs before or after the actual fusion event.

Cyclic AMP-independent secretion of mucin by SW1116 human colon carcinoma cells. Differential control by Ca2+ ionophore A23187 and arachidonic acid.

The regulation of mucin secretion by SW1116 human colon carcinoma cells has been studied using monoclonal antibody 19-9, which has previously been used to detect mucin in the serum of cancer and cystic fibrosis patients. We found that SW1116 cells constitutively secrete considerable amounts of mucin as the predominant glycoprotein. The secretion of mucin by these cells is independent of cyclic AMP levels, but can be further stimulated by the Ca2+ ionophore A23187.

Flat embedding and immunolabelling of SW 1116 colon carcinoma cells in LR white: an improved technique in light and electron microscopy.

Human SW 1116 colon carcinoma cells were grown on matrix-covered coverslips and flat embedded in specially prepared gelatin capsules in the hydrophylic resin LR White. Dehydration and polymerization were carried out so as to maximize preservation of antigenicity. Sections were cut perpendicular to the substratum.

Identification and ultrastructural localization of a calretinin-like calcium-binding protein (protein 10) in the guinea pig and rat inner ear.

Calretinin has been identified as a brain specific calcium-binding protein which appears as a prominent protein in the cochlear nucleus. We identified and localized calretinin in the guinea pig and rat inner ear using polyclonal antibodies. Immunoblot analyses of guinea pig and rat auditory nerve homogenates revealed an immunoreactive band migrating with the same molecular weight as the purified protein, at Mr = 29 k.

Identification and localization of a kainate binding protein in the frog inner ear by electron microscopy immunocytochemistry.

A kainate binding protein (KBP) was studied in Rana pipiens inner ear using monoclonal and polyclonal antibodies against affinity purified KBP from frog brain. The KBP identified and analyzed in inner ear tissue homogenates, with one- and two-dimensional immunoblots, was similar to the affinity purified KBP and to the antibody-identified frog brain KBP. As brain KBP, inner ear KBP had 5 main components in the molecular weight dimension, centered at Mr = 48,000; however, inner ear KBP had a greater abundance of the higher molecular weight components.

Characterization of a calcium current in a vertebrate cholinergic presynaptic nerve terminal.

Calcium currents were recorded from a cholinergic presynaptic nerve terminal in the chick ciliary ganglion using the whole-cell voltage-clamp technique. The presynaptic element of this synapse is in the form of a calyx that envelops the postsynaptic ciliary neuron. A method was developed to isolate the ciliary neuron, expose the calyx, and apply patch-clamp electrodes under visual control.

Preparation of affinity-purified, biotinylated tetanus toxin, and characterization and localization of cell surface binding sites on nerve growth factor-treated PC12 cells.

Biotinylated derivatives of tetanus toxin were prepared and isolated by chromatofocusing and ganglioside-affinity chromatography. Biotinylation was monitored by the appearance of a 210,00 dalton complex upon SDS-polyacrylamide gel electrophoresis in the presence of avidin, and by selective binding to an avidin-Sepharose gel. At molar biotin:toxin ratios from 1:1 to 20:1 only biotinylated derivatives with low toxicity were obtained; these derivatives, however, retained 60-80% of their specific binding affinity for brain synaptosomes.

Distribution of a putative kainic acid receptor in the frog central nervous system determined with monoclonal and polyclonal antibodies: evidence for synaptic and extrasynaptic localization.

A frog brain kainic acid receptor (KAR) was studied using monoclonal and polyclonal antibodies against the affinity-purified receptor. Immunocytochemistry was done on sections of the frog CNS, and the distribution of immunostaining was compared with the distribution of high- and low-affinity 3H-kainic acid (3H-KA) binding sites determined with in vitro receptor autoradiography. These studies showed (1) similar distributions of high- and low-affinity 3H-KA binding sites, (2) identical patterns of immunostaining with the polyclonal antibodies and 2 monoclonal antibodies, and (3) an antibody binding distribution which closely matched that of 3H-KA binding, suggesting that the antibodies recognize the primary KAR in frog brain.