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Biomedical subjects

A Smolka

Publications and source records attributed to A Smolka.

25 records · Page 2Linked to original sources
PubMed1988

Monoclonal antibodies to the H+-K+ ATPase of gastric mucosa selectively stain the non-pigmented cells of the rabbit ciliary body epithelium.

Monoclonal antibodies developed against the transport enzyme H+-K+ ATPase of gastric mucosa selectively bind to the nonpigmented cell layer in both the pars plana and pars plicata of the rabbit ciliary body epithelium. The most specific of these antibodies (HK 12.18) reacts with the nonpigmented cells but with no other cell type in ciliary body, retina or iris. Antibody reactivity is evinced by a distinct particulate staining which is greater on the surfaces of the nonpigmented cells than within the cytoplasm and seems most intense on the apical membrane between the pigmented and nonpigmented cell layers. This pattern of staining was present in 2-3-day-old pups and in young adults, in both pigmented and albino animals. Similar staining was not observed in control sections treated with preimmune serum, nonspecific mouse monoclonal antibody, or HK 12.18 preabsorbed to gastric microsomes. In addition to staining intact ciliary body, the antibody HK 12.18 can be shown to react with a population of cells lacking pigment granules in suspensions of dissociated ciliary body epithelium. This antibody may therefore be useful as a marker for the identification of nonpigmented cells in tissue culture.

Animals↗
PubMed1986

Immunoassay of pig and human gastric proton pump.

Monoclonal antibodies against the K+-dependent adenosine triphosphatase (ATPase) responsible for acid secretion in the pig gastric mucosa were generated by hybridoma technology. Two of these antibodies, shown to bind selectively to subunits of the ATPase and to label intracellular membranes of pig and rabbit parietal cells, were used to develop a sensitive (less than 1 pmol) immunoassay for the ATPase. Enzyme samples were adsorbed to the wells of polystyrene microtitration plates and then incubated sequentially with monoclonal antibody, antimouse immunoglobulin G coupled to alkaline phosphatase, and p-nitrophenyl phosphate. Standard curves relating the absorbance of the wells at 410 nm to log10 micrograms ATPase were fitted by a three-parameter logistic, with a useful assay range of 0.05-10 micrograms ATPase. The immunoassay allows measurement of proton-pumping ATPase levels in human gastric biopsy specimens and may therefore be useful in studies of gastric mucosal function.

Adenosine Triphosphatases↗
PubMed1984

Isolation of pepsinogen granules from rabbit gastric mucosa.

Pepsinogen granules were isolated from rabbit stomachs by a combination of differential and isopycnic gradient centrifugation. The isolation procedure utilized 1 M sucrose and alkaline pH to stabilize the granules. The isolated granules were shown to be 8.4-fold enriched in pepsinogen and free of mitochondria and microsome enzyme markers. In addition to pepsinogen, a cation-insensitive but anion-sensitive Mg2+-ATPase co-purified with the zymogen. The enzyme was unaffected by aurovertin, oligomycin, and ouabain, but inhibited by high concentrations of vanadate, N,N'-dicyclohexylcarbodiimide, and azide. The enzyme activity was stimulated by tetrachlorosalicylanilide and the combination of valinomycin and nigericin in K+-containing media. The similarities between this enzyme and other secretory granule ATPases are discussed.

Adenosine Triphosphatases↗
PubMed1983

Monoclonal antibodies against gastric H+ + K+ ATPase.

Monoclonal antibodies were prepared against a purified membrane fraction from hog gastric mucosa containing the H+ + K+ ATPase. On sodium dodecyl sulfate gels the molecular weight of this fraction corresponds to a single band of about 95,000. In contrast, on isoelectric focusing gels three groups of peptides are resolved with isoelectric points of 5.7, 6.2, and 8.5. One of the monoclonal antibodies (HK111) was shown to react selectively with the acidic peptide, whereas another antibody (HK113) reacted with the alkaline peptide, showing that the three peptides were antigenically distinct. Both monoclonal antibodies selectively labeled the parietal cell, and antibody HK111 labeled the tubulovesicles of the resting parietal cell and the microvilli of the secretory canaliculus of the secreting cell. This finding suggests translocation of membrane from the tubulovesicles to the secretory surface on stimulation.

Adenosine Triphosphatases↗
PubMed1983

Proton secretion by the gastric parietal cell.

The parietal cell occupies a unique niche among eukaryotic cells in that it develops a proton gradient of more than 4 million-fold across the membrane of the secretory canaliculus. At rest, the cell is still able to develop a proton gradient across intracellular membranes, such that the acid compartment has a pH of less than 4. Acidification depends on the simultaneous presence of ATP, K+ and Cl- as demonstrated in permeabilized cells. With acidification of the luminal side of the proton pump, there is a corresponding alkalinization of the cytosolic face as revealed by carboxyfluorescein fluorescence enhancement. Disposal of the resultant alkali depends on carbonic anhydrase activity and the functioning of a coupled Na+:H+ and Cl-:OH-antiport across the basal lateral membrane. Accordingly, with secretion there is an increased cellular Cl- level, which is exported across the apical membrane in association with K+. The Na+ pump dependent secretion of KCl across this membrane is one of the major sites of the gastric ATPase. Membranes isolated from secreting tissue contain a KCl permeation pathway largely absent from membranes isolated from resting tissue. The pump itself acts as an H+ for K+ exchange ATPase which is most probably composed of at least two peptides of 100 000 Mr. That catalytic cycle consists of formation and breakdown of a covalent aspartyl phosphate. Formation of the intermediate depends on loss of K+ from cytosolic binding sites, and breakdown of the intermediate depends on K+ binding to the luminal face of the enzyme. During breakdown, an acid labile E . P is formed, and, at high ATP concentrations, loss of this form of the enzyme is probably the rate limiting step.

Adenosine Triphosphatases↗