Binding of IgG to amyloid beta A4 peptide via the heavy-chain hinge region with preservation of antigen binding

Amyloid beta A4 peptide is found in the extracellular region of the senile plaque and in the angiopathy of Alzheimer's disease. Several other proteins, including IgG, also reside in these abnormal structures. In an attempt to understand how these structures are assembled and to determine how proteins are recruited, interactions of various proteins with synthetic beta A4 peptide have been examined in vitro. Purified IgG binds directly to synthetic beta A4 peptide with high avidity. The domain between amino acids 12-28 of beta A4 binds IgG. beta A4 peptide binds the hinge region of the immunoglobulin heavy chain, and preserves the ability of the immunoglobulin to bind antigen. A protein which does not bind directly to beta A4 peptide can be targetted to the senile plaque and angiopathy by binding to IgG, which avidly binds beta A4 peptide.

Interaction of indoleacrylic acid with Trp aporepressor from Escherichia coli

Trans-beta-Indoleacrylic acid (IAA) binds with moderately high affinity to the dimeric protein, trp aporepressor from Escherichia coli. IAA is itself nonfluorescent, and, upon binding, IAA quenches approximately 95% of the intrinsic tryptophan fluorescence of the protein. Since there is an overlap between the absorbance of IAA and the emission of tryptophan, this quenching appears to be due to resonance energy transfer. To adequately fit binding isotherms, it was necessary to use a model in which the binding of IAA to one subunit is able to quench fluorescence from both subunits of the protein. This model also assumes that binding to the two subunits occurs independently. Binding data were obtained as a function of the concentration of trp aporepressor, over the range of 1 x 10(-8) to 5 x 10(-5) M, in order to test the possibility that protein subunit association or dissociation occurs. When analyzed in terms of the above model, no significant protein concentration dependence is seen for the IAA association constant, indicating that either (i) the protein does not undergo changes in oligomerization over this concentration range or that (ii) different states of aggregation bind IAA with similar affinity. The affinity of IAA was found to increase at higher ionic strength and at lower pH. Also, evidence is presented for a photoinduced change in the configuration of IAA.

Prolonged regional nerve blockade by controlled release of local anesthetic from a biodegradable polymer matrix

BACKGROUND

Prolonged nerve blockade is potentially useful in the management of many acute and chronic pain problems. Aside from infusions via an indwelling catheter, most currently available nondestructive techniques for prolonging local anesthetic action cannot provide more than 1-2 days of blockade. Bioerodible polymer matrixes have been used to deliver a variety of drugs in patients and animals for periods lasting weeks to years. Previously, dibucaine and bupivacaine were incorporated into copolymers of 1,3 bis(p-carboxyphenoxy) propane-sebacic acid anhydride (1:4), and demonstrated sustained release in vitro following incubation of the drug-polymer matrixes in phosphate-buffered solution (pH 7.4, 37 degrees C).

METHODS

In the present study, cylindrical pellets made from polymer matrixes incorporated with bupivacaine-HCl were implanted surgically along the sciatic nerves of rats. Neural block was assessed by direct observation of motor skills and by leg-withdrawal latency to a hot surface. Biochemical and histologic examinations were performed 2 weeks after implantation.

RESULTS

Sensory and motor blockade was produced for periods ranging from 2 to 6 days. Contralateral control legs receiving polymer implants without drug showed no block. Blockade was reversible, and animals appeared to recover sensory and motor function normally. Biochemical indexes of nerve and muscle function were indistinguishable from contralateral controls.

CONCLUSIONS

This biodegradable polymer system provides a promising new alternative for the delivery of local anesthetics to peripheral nerves to produce prolonged blockade for the management of acute and chronic pain.

Studies on antibiotic 230 as a molluscicide

In the course of studying molluscicidal effects of microorganisms, a microorganism belonging to Streptomycetaceae, Streptomyces griseolus (Strain 230) was isolated from soil and a certain microbial ingredient proved to have a molluscicidal activity. The effective substance was named antibiotic 230. As a result of several investigations on the antibiotic, the following chemical features were made clear. The chemical substance was an indol-carbazole-heterocyclic compound, the molecular weight 446 and the molecular formula C28H26N4O3. The antibiotic demonstrated a molluscicidal effect against Oncomelania snails and their eggs both in the laboratory and in the field. The compound had a wide bacteriostasis spectrum and a slight toxicity to fish in addition to the above, but it was non-toxic to plants.

[HPLC--detection of hydroxyl radicals in striatum extracellular fluid in rats subjected to reperfusion after cerebral ischemia and the action of vitamin E]

The formation of hydroxyl radical in the extracellular fluid in striatum of rats subjected to 4-vessel occlusion during ischemia and reperfusion was measured by HPLC with UV detector using salicylic acid as a trapping agent. Hydroxyl radicals react with salicylic acid yielding 2,3- and 2,5-dihydroxybenzoic acids which can be separated by liquid chromatography. The striatum was perfused with artificial cerebrospinal fluid containing 0.5 mmol.L-1 salicylic acid at a flow rate of 2.5 microliters.min-1. The results indicate that the concentration of 2,5-dihydroxybenzoic acid in the perfusates was highest during 25 min reperfusion and no change was found during ischemia. Vit E at 30, 60 and 120 mg.kg-1 i.p. 20 min before ischemia was shown to dose dependently suppress the rise of 2,5-dihydroxybenzoic acid after reperfusion. The results suggest that the HPLC method is useful and reliable for the measurement of hydroxy radical in global ischemia in vivo.

A highly sensitive enzyme-linked immunosorbent assay for Clostridium perfringens enterotoxin

A highly sensitive enzyme-linked immunosorbent assay (ELISA) for quantitation of Clostridium perfringens enterotoxin (CPE) by a sandwich method with polystyrene beads was elaborated. The ELISA was very sensitive with a detection limit of 1 pg/ml of CPE. Clostridium perfringens culture fluid did not interfere with the assay. This ELISA may be useful for the mass screening for Cl. perfringens producing small amounts of CPE.

[A primary report on thrombolytic therapy of acute myocardial infarction in 40 cases]

Forty cases with acute myocardial infarction were treated by thrombolysis from June, 1989 through September, 1990. 32 males and 8 females. Age 44-76 (60 +/- 7.1) years. Coronary angiography was performed in 19 patients 10 days after intravenous thrombolysis on average. With intravenous thrombolysis the reperfusion rates were 69.2% (9/13) for streptokinase and 53.8% (7/13) for urokinase (Green Cross Company, Japan) according to the clinical criteria. No reperfusion was observed in 8 cases treated by China-made urokinase. The reperfusion rate of intracoronary thrombolysis was 85.7% (6/7). 5 cases had hemorrhagic complications, skin ecchymosis in 2 and mild gastrointestinal bleeding in 3, and no transfusion was necessary. No intracranial hemorrhage was noticed.

Insulin rapidly induces rat liver S14 gene transcription

We evaluated the role insulin plays in the regulation of hepatic S14 gene transcription using the streptozotocin-induced diabetic rat model. Nuclear run-on activity and mRNAS14 levels were reduced by more than 85% in diabetic rats compared to those in intact animals. After the administration of insulin, both S14 run-on activity and mRNAS14 levels were rapidly induced. Within 1 h of insulin administration, S14 run-on activity and mRNAS14 were induced 5- and 8-fold, respectively. S14 gene expression was restored to intact levels within 4 h, with overall increases in run-on activity and mRNAS14 of 7- and 20-fold, respectively. The full induction of mRNAS14 cannot be accounted for solely by activation of S14 gene transcription, implicating insulin effects at the posttranscriptional level. However, our results show that the principal target for insulin action on the S14 gene is transcriptional. Administration of dibutryl cAMP and theophylline fully blocked the insulin-mediated increase in S14 gene transcription, indicating that hepatic cAMP levels play a dominant negative role in regulating S14 gene transcription in vivo. Fructose administration to starved diabetic rats induced only a marginal 60% increase in mRNAS14 and S14 run-on activity within 4 h, while insulin plus fructose or insulin plus glucose fully restored S14 gene expression to intact levels within the same time period. Thus, dietary fructose or a metabolite generated from fructose alone cannot induce S14 gene transcription or mRNAS14 to intact levels in the starved diabetic rat. Acute effects of dietary carbohydrate on hepatic S14 gene transcription are insulin dependent.(ABSTRACT TRUNCATED AT 250 WORDS)

Dumbbell metastatic cystosarcoma phyllodes of the heart and lung

Cystosarcoma phyllodes is an uncommon breast tumor that rarely metastasizes. A case of dumbbell cystosarcoma phyllodes metastatic to the heart and lung diagnosed antemortem is described. The roles of diagnostic echocardiography and surgical excision are discussed. Atrial extension of a lung malignancy through a pulmonary vein is not an absolute contraindication to operation, but careful patient selection and operative planning are required.

Effects of clofilium on ischemic subendocardial Purkinje fibers 1 day postinfarction

One day after ligation of the canine anterior descending coronary artery, clofilium, a long-acting class III antiarrhythmic agent, was studied for its effects on normal and ischemic Purkinje fibers. In normal Tyrode's solution (4 mM potassium, 2.7 mM calcium) clofilium (10(-7) to 10(-5) M) increased action potential duration. Although only 2 of 10 normal Purkinje fibers developed early after depolarizations and early afterdepolarization-initiated triggered activity, 10 of 11 ischemic Purkinje fibers developed these features. Consequently, action potentials in ischemic fibers were prolonged to durations greater than 10 s. The triggered activity in the ischemic Purkinje fibers produced repetitive activity in adjacent normal ventricular muscle. In vivo, 3 days after ligation, the administration of 3 to 10 mg/kg clofilium induced grouped beating. Action potentials recorded subsequently from these same hearts in vitro showed early afterdepolarizations, triggered activity and a similar grouping of responses. Therefore, clofilium differentially produced early afterdepolarizations in ischemic Purkinje fibers. This is a mechanism by which clofilium could be arrhythmogenic in an ischemic heart.

Dietary obesity in rats: influence on carbohydrate metabolism

When male rats were fed a high diet from 3 to 20 weeks of age, they weighed 633 g which was 30% more than the animals fed a high glucose diet. Blood samples after a 16 to 18 hour fast, from the rats fed the high fat and high glucose diets contained, respectively: 130 +/- 11, 110 +/- 8 mg glucose/100 ml; 27 +/- 5, 24 +/- 3 microunits immunoreactive insulin (IRI)/ml; 791 +/- 58, 1104 +/- 179 meq nonesterified fatty acids (NEFA)/L. A tolerance test, by stomach tube, with 125 mg of glucose/100g body weight indicated that the rats fed the high fat diet had significantly higher mean plasma glucose concentrations, lower IRI responses and a lower leve of NEFA than rats fed a high glucose diet. Switching diets for 5 weeks resulted in body weights of about 600 g for both groups of rats. Those rats switched from the high fat to the high glucose diet did show an improved glucose tolerance, while the reverse was true of rats switched from the high carbohydrate to the high fat diet.