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E Straus

Publications and source records attributed to E Straus.

At least 55 records · Page 3Linked to original sources
PubMed1979

Cholecystokinin in the brains of obese and nonobese mice.

Extracts of the cerebral cortes of genetically obese (ob/ob) mice with hyperphagia contain 0.05 +/- 0.02 microgram (mean +/- standard error) of cholecystokinin octapeptide equivalent per gram of wet weight compared to 0.15 +/- 0.01 microgram per gram for their nonobese littermates and 0.20 +/- 0.01 microgram per gram for normal LAF1 mice. These findings are suggestive of a causal relation between the diminished brain immunoreactive cholecystokinin content and the unrestrained appetite of the obese mice.

Animals↗
PubMed1979

Gastrointestinal peptides in the brain.

Both immunoreactive intact cholecystokinin (CCK33) and its COOH-terminal octapeptide (CCK8) are detected in brain and gut extracts of monkey, dog, and pig using an antiserum with equivalent sensitivities for detecting CCK8 in the free form or when incorporated in the intact molecule. The failure to detect intact cholecystokinin in extracts from monkey or dog by using an antiserum developed by immunization with porcine CCK33 is due to marked species differences in the NH2-terminal portion of the molecule. Immunohistochemical staining reveals the presence of CCK peptides in rabbit cerebral cortical tissue neurons. Subcellular fractionation of rat cerebral cortical tissue demonstrates that CCK immunoreactivity is concentrated in the pellet identified by electron microscopy to contain a high proportion of synaptic vesicles. A converting enzyme that differs from trypsin has been partially purified from canine and porcine cerebral cortical extracts. It converts porcine CCK to smaller immunoreactive forms, but fails to convert big gastrin to heptadecapeptide gastrin. This enzyme differs from trypsin not only in substrate specificity but also in several physicochemical properties. Cerebral cortical extracts from hyperphagic ob/ob mice have strikingly lower contents of CCK than those from their lean littermates and other normal mice. These studies taken together are consistent with a role for CCK as a neurotransmitter involved in the overall regulation of appetite.

Animals↗
PubMed1978

Species specificity of cholecystokinin in gut and brain of several mammalian species.

Immunoreactive intact cholecystokinin and its COOH-terminal octapeptide are found in brain as well as in extracts of gut of the monkey, dog, and pig, by using an antiserum with equivalent sensitivities for detecting the octapeptide in free form or incorporated in the intact molecule. The failure to detect intact cholecystokinin in extracts from monkey or dog by using an antiserum developed by immunization with porcine cholecystokinin is presumed to be due to marked species differences in the NH2-terminal portion of the molecule. Tryptic digestion converted the intact cholecystokinin from all species to a peptide resembling the COOH-terminal octapeptide. The amount of cholecystokinin in the brain is comparable to that found in the gastrointestinal tract, the traditional site for this peptide.

Animals↗
PubMed1978

Characterization of a nontrypsin cholecystokinin converting enzyme in mammalian brain.

An enzyme has been partially purified from canine and porcine cerebral cortical extracts that differs from trypsin in that it manifests some degree of hormone specificity since it converts porcine cholecystokinin to smaller immunoreactive forms, i.e., the COOH-terminal dodecapeptide and octapeptide fragments, but fails to convert big gastrin (34 amino acids) to heptadecapeptide gastrin. This enzyme is distinguishable from trypsin not only in substrate specificity, but also in several physiochemical properties. It is not inhibited in the presence of concentrations of lima bean trypsin inhibitor sufficient to inhibit 1 mg of trypsin per ml of incubation mixture. It is inactivated when incubated with substrate at 45 degrees C for 1 hr, whereas trypsin remains fully active when incubated under the same conditions at 55 degrees C. The enzyme elutes in the void volume on Sephadex G-50 and G-75 gel filtration. On sucrose gradient centrifugation, the proteolytic activity associated with trypsin is recovered above albumin but that of the solubilized brain enzyme is recovered below gamma globulin. The enzyme is not detectable in splenic extracts, which do contain nonspecific proteases capable of completely degrading cholecystokinin. Further investigation is required to determine whether the enzyme in the gut that converts cholecystokinin to the bioactive and immunoactive COOH-terminal fragments resembles or is different from the brain converting enzyme.

Animals↗
PubMed1978

Localization of cholecystokinin-like immunoreactivity in isolated nerve terminals.

Subcellular fractionation of the rat cerebral cortex demonstrated the presence of immunoreactive cholecystokinin in the pellet identified by electron microscopy as containing a high proportion of synaptic vesicles. The recovery in this pellet of 40% of the total immunoreactivity in the initial cortical extract is quite comparable to the recovery of other peptides such as vasoactive intestinal polypeptide and somatostatin, which are also located in synaptosomes and for which roles as neuroregulators or transmitters have been suggested. The evidence of concentration of cholecystokinin-like peptides in the synaptosomal pellet is consistent with our earlier demonstration by immunohistochemical techniques of cholecystokinin's presence in rabbit cerebral cortical neurons. These observations and the evidence for diminished concentration of cholecystokinin-like peptides in the brains of hyperphagic mice are consistent with cholecystolinin's suggested role as a neuroregulator for appetite.

Animals↗
PubMed1978

Immunoreactive secretin in gastrointestinal mucosa of several mammalian species.

Immunoreactive secretin in hydrochloric acid extracts is relatively constant in the duodenum and proximal jejunum of pig and dog (3 microgram per g), but peaks in the distal duodenum of guinea pig (1 microgram per g), no secretin being detectable in the ileum of these species. Secretin is relatively constant throughout the small intestine of the rat and rabbit (0.4 to 0.1 microgram per g). Sephadex gel filtration patterns of all species and throughout the gastrointestinal mucosa revealed primarily a single peak with elution characteristics identical with that of purified or synthetic porcine secretin. The "big" secretin prominent in Boots secretin may be an alteration product perhaps attributable to chemicals used to stabilize the preparation. The "intermediate secretin" described by others has not been detected. It is concluded that in a variety of mammalian species most of the immunoreactive secretin extractable from the intestinal tract lies distal to the proximal duodenum and is not distinguishable from duodenal secretin in terms of molecular size.

Animals↗
PubMed1977

Cholecystokinin and its COOH-terminal octapeptide in the pig brain.

Two components--one resembling intact cholecystokinin in size and charge and immunologic specificity, and the other resembling the COOH-terminal octapeptide of cholecystokinin--have been found in extracts of the pig cerebral cortex. The relative concentrations of the two peptides in the extracts were dependent on the extractant, boiling 0.1 M HCl being more effective than boiling water for the extraction of intact cholecystokinin but less effective for the extraction of the octapeptide. The physiologic role of these peptides in the brain has yet to be elucidated.

Animals↗
PubMed1977

Canine Zollinger-Ellison syndrome.

The unusual finding of peptic esophagitis and duodenal ulceration in a dog was associated with a malignant pancreatic islet cell tumor producing gastrin and ACTH. The finding of a gastrinoma in a non-human species introduces the potential for developing an animal model for the study of the protean genetic biochemical, physiologic and metabolic aspects of the Zollinger-Ellison syndrome.

Adrenocorticotropic Hormone↗
PubMed1976

Some considerations in the preparation of raioiodoinsulin for radioimmunoassay and receptor assay.

125I-insulins, prepared by iodination with chloramine T in marked excess or by stepwise, stoichiometric addition of the oxidizing agent, were compared with respect both to their molecular distribution of iodine and to their suitability for use in a cultured lymphocyte receptor assay. Iodination of insulin in aqueous solution results in the same distribution of iodine atoms, independent of experimental method and dependent only on the average iodine number. This distribution can be calculated on the basis of a Monte Carlo simulation, For insulin iodinated at an average of 0.8 I atoms per molecule, approximately 50 per cent of the radioactivity is in other than monoiodoninsulin. Purification methods that separate on the basis of charge, such as starch-gel electrophoresis, are then required, to obtain monoiodoinsulin. More highly iodinated insulin do bind to the lymphocyte receptor, although, as in radioimmunoassay, the overiodinated species are less satisfactory for use as tracers. The shelf life of iodinated insulin appears to be related better to the average iodine content than to any other factor, presumably because of decay catastrophe. There is no evidence to suggest that exposure to chloramine T in marked excess for a few seconds is deleterious to insulin.

Chloramines↗
PubMed1976

Artifacts in the radioimmunoassay of peptide hormones in gastric and duodenal secretions.

Observations of apparently high concentrations of gastrin and insulin in gastric and duodenal secretions as determined by radioimmunoassay may arise from artifacts caused by proteolytic enzymes. The double-antibody and charcoal separation techniques as commonly employed fail to recognize extensive proteolytic damage to labeled antigen and to antibody.

Antigen-Antibody Reactions↗
PubMed1975

Molluscan gastrin: concentration and molecular forms.

Blood and gastrointestinal tissues of the sea hare Aplysia californica and the land snail Otala lactea contain immunoreactive gastrin in heterogeneous forms similar to those of mammals. The observation that blood concentrations in terms of porcine gastrin standard are comparable to those of pig, man, and dog suggests significant homology between the structures of molluscan and mammalian gastrins.

Animals↗