Major L. Cohn

Neuroendocrine Peptides - Analysis by Reversed Phase High Performance Liquid Chromatography

Abstract A high performance liquid chromatographic (HPLC) method is described for determining the biologically active neuroendocrine peptides thyrotropin releasing hormone (TRH), leucine (leu) and methionine (met) enkephalin, angiotensin II, delta sleep inducing peptide (DSIP), luteinizing hormone releasing hormone (LHRH), substance P and growth hormone release inhibiting factor (somatostatin). The selection of mobile phases was limited to these systems that do not exhibit strong absorbtion at 215 nm and 254 nm. Under isocratic conditions at room temperatures with the appropriate selection of mobile phase it was possible by reversed phase chromatography to resolve all of the peptides investigated. We can resolve with the systems employed peptides differing by only one amino acid in chain length as well as peptides differing by only one amino acid in the chain sequence. The method is rapid, does not require derivitization, can be used with aqueous matrixes and is sensitive in the nanomolar range. Our resea...

A direct effect of dibutyryl cycluc AMP on the duration of narcosis induced by sedative, hypnotic, tranquiliser and anaesthetic drugs in the rat ☆

Abstract The ability of exogenously administered N6, O2′-dibutyryl analogue of cyclic AMP to shorten, in a dose-related manner, the duration of narcosis of eight structurally different agents (chloral hydrate, paraldehyde, diazepam, amobarbital, halothane, ketamine, ethanol and methanol) has been demonstrated in the rat. No other nucleotide, neurotransmitter, biogenic amine or hormone tested, shortened, in a dose-related manner the sleeping time induced by the anaesthetic agents.

Epidural morphine and methylprednisolone. New therapy for recurrent low-back pain.

Twenty patients with intractable, postoperative, recurrent low-back pain were treated with a sequential, epidural injection of morphine (8 mg) and methylprednisolone acetate (80 mg). Concomitantly administered, these drugs provided 50-100% pain relief lasting 6-24 months and elicited prolongations of mood elevation and morphine-induced side effects. Evidence from computed tomography and electromyography, however, indicated no amelioration of pre-existing pathologies.

Regulation of behavioral events by thyrotropin releasing factor and cyclic AMP.

Like dibutyryl cyclic AMP, thyrotropin releasing factor (TRF) has potent antianesthetic properties, but only dibutyryl cyclic AMP shortens narcosis dose-relatedly. In contrast, only TRF reverses amobarbital-induced hypothermia (dose-relatedly). In naive rats, dibutyryl cyclic AMP (25-200 mug) induces convulsions while TRF (5-100 mug) produces intermittent hyperactivity and sedation but never convulsions. To determine whether behavioral events may be regulated in the central nervous system through an interaction of the two naturally occurring compounds, TRF (5-100 mug) and dibutyryl cyclic AMP (25-200 mug) were injected simultaneously into the lateral ventricle of the brain of naive rats or rats anesthetized with amobarbital (80 mg/kg). TRF (12.5-50 mug) and dibutyryl cyclic AMP (100-200 MUG) DID NOT SHORTEN NARCOSIS FURTHER THAN DIBUTYRYL CYCLIC AMP alone. Amobarbital protected against the lethal effects of the two compounds injected simultaneously. Long-lasting locomotor disorders and mortality rate increased with increasing doses of TRF (12.5-25 mug) and dibutyryl cyclic AMP (100-200 MUG) GIVEN TO NAIVE RATS. Results did not support the postulate that cyclic AMP is the second messenger of TRF.

Comparisons between the antianesthetic action of dibutyryl cyclic AMP and analeptic drugs on amobarbital-induced narcosis in the rat.

The dose-related antianesthetic and antidotal property of dibutyryl cyclic AMP, devoid of toxic effects, imparts uniqueness to the nucleotide as an arousal agent. Of the analeptic drugs studied (d-amphetamine, picrotoxin, pentylenetetrazol, caffeine, theophylline, strychnine, ethamivan and doxapram), only picrotoxin demonstrated antianesthetic properties. However, picrotoxin was associated with severe toxicity at all dose levels tested. No analeptic drug is effective in reversing the central nervous system depression produced by sedative, hypnotic or tranquilizer drug overdosage.

Studies on the distribution and properties of the multiple forms of mammalian lipoamide dehydrogenase

Abstract Lipoamide dehydrogenase (NAD + ·NADH:lipoamide oxidoreductase, EC 1.6.4.3) was obtained from pig heart muscle by three different isolation procedures and subjected to electrofocusing and analytical acrylamide gel electrophoresis. Five or six enzymically active anodal species are resolved by these techniques. Three higher mobility species are obtained from lipoamide dehydrogenase derived from pyruvate dehydrogenase complex having isoelectric points of between pH 5.6 and 6.0, while three slower mobility species obtained from α-ketoglutarate dehydrogenase-derived lipoamide dehydrogenase have isoelectric points of between pH 6.5 and 6.8. These multiple species are invariant throughout these isolation procedures. They are identified as charge isomers with similar molecular weights and amino acid composition. Evidence is presented that these multiple species are not solely the result of alteration of lipoamide dehydrogenase by the proteolytic enzymes of pig heart.

Measurements of brain amobarbital concentrations in rats anesthetized and overdosed with amobarbital and treated centrally with dibutyryl cyclic AMP

Abstract Three doses of amobarbital, an anesthetic dose (80 mg/kg), a minimum lethal dose (130 mg/kg), and a high lethal dose (180 mg/ kg) were administered intraperitoneally to groups of rats. All rats were injected intracerebroventricularly with 0.9% saline or dibutyryl cyclic AMP, 200 μg/rat. While those rats treated with saline solution were still sleeping at decapitation and those treated with dibutyryl cyclic AMP were awake, there were no significant differences in their brain concentrations of amobarbital.

Low-Frequency Magnetic Field Technology: Quantifying Spinal Range of Motion

Reliability of a sensitive, noninvasive technique for quantifying spinal range of motion was assessed by investigators who measured lumbar mobility of 19 subjects with no history of low-back pain or spinal abnormalities. The measurement method used low-frequency, quasistatic magnetic dipole field and sensors which disturb this field in a precisely quantifiable manner. Sensors, affixed to the skin over T12 to L1 interspace and over the sacrum at the level of S1, were directly interfaced with an IBM PC-AT microcomputer, which was used for error-free collection and storage of data. Measurement results compared favorably to those obtained from the biplanar radiographic technique. Statistical analysis showed an extremely high degree of intraobserver and interobserver reliability. Additional advantages included simplicity and noninvasiveness. Overall, the magnetic field technique proved a significant advancement in clinically quantifying spinal mobility, allowing precise determination of impairment under American Medical Association guidelines.

PROPERTIES OF MULTIPLE MOLECULAR FORMS OF LIPOAMIDE DEHYDROGENASE 1

ABSTRACT. Multiple forms of lipoamide dehydrogenase (NAD + -NADH: lipoamide oxidoreductase, EC 1.6.4.3) have been isolated from a variety of mammalian tissues. Sixmain enzymically active anodal species can be separated of which three are associated with the pyruvate dehydrogenase complex and three with the α-ketoglutarate dehydrogenase complex. Whether or not these isozymes exist in vivo or arise as a consequence of the experimental conditions employed in the isolation of lipoamide dehydrogenase has beenthe subject of several previous investigations. Further experimental efforts, includingthe use of the proteolytic enzyme inhibitor, pepstatin, during enzyme purification and isolation of the isozymes from sonicated fresh pig heart mitochondria, provide evidenceagainst a solely artifactual origin.