Nuclear magnetic resonance relaxation in cross-linked lysozyme crystals: an isotope dilution experiment.

Nuclear magnetic resonance (nmr) relaxation times are measured for water protons in cross-linked lysozyme crystals below the freezing event as a function of the mole fraction of protons in the water phase. Proton longitudinal nmr relaxation in these samples is nonexponential and the slow longitudinal relaxation component becomes slower linearly with decreasing proton mole fraction in the water. The data are analyzed using a cross relaxation model that eliminates the necessity of postulating long residence times for water molecules in the domain of the protein. The observed isotope dilution behavior is consistent with the cross relaxation model. The deuterium nmr relaxation is also reported for deuterium oxide in the cross-linked protein crystal sample below the freezing event and the relaxation is shown to be accurately exponential.     

A vibrational study of the CD2 stretching bands of selectively deuterated palmitic and stearic acids

The C-D stretching regions of the infrared and Raman spectra of 14 different palmitic and stearic acids containing isolated CD₂ groups are reported. Anomalous behaviour is observed when substitution occurs near the terminal methyl group, which behaviour can not be explained in terms of crystal field effects.     

Le ionophore A23187

The acrosomic status of spermatozoa prepared for IVF has been evaluated by means of immunofluorescence test from Fenichel and Hsi using calcium A 23187 ionophore as inductor of acrosome reaction (AR). The spontaneous AR remains slight, even after 6 hour-incubation in Menezo B2 (6,8+2,7%). The response to ionophore, moderate before (11,2+9%), frankly increases after a 6h-capacitation (28,9+8,3%) in a group of 25 IVF couples (tubal indication, normal semen, positive fertilization). Nevertheless, it remains slight or null in 4 cases of unexplained repeated failure of fertilization. The response to ionophore A 23187 allows to explore the kinetics of capacitation of spermatozoa and their ability to perform AR. Its significance in terms of fecondance remains to be precised.     

A specific and potent immunotoxin composed of antibody ZME-018 and the plant toxin gelonin

Murine monoclonal antibody ZME-018 recognizes a 240 Kda glycoprotein present on the surface of most human melanoma cells and on over 80% of human biopsy specimens tested. Gelonin is a ribosome-inactivating plant toxin similar in nature and rivaling the activity of ricin A chain. ZME-018 was coupled to purified gelonin using the reagents SPDP and 2-iminothiolane. The ZME-gelonin conjugate was purified by S-300 Sephacryl and Blue Sepharose chromatography, removing unreacted gelonin and antibody, respectively. PAGE analysis showed that ZME was coupled to 1, 2, or 3 gelonin molecules. The ZME-gelonin conjugate was 10(6)-fold more active than gelonin itself in inhibiting the growth of log-phase human melanoma cells in culture. The immunoconjugate was not cytotoxic to antigen negative T-24 (human bladder carcinoma) cells. Treatment of melanoma cells with recombinant IFN-alpha or TNF substantially augmented the cytotoxicity of the immunoconjugate while treatment with IFN-gamma had a minor effect. Using the human tumor colony assay of melanoma cells obtained from fresh biopsy specimens, greater than 90% growth suppression was observed in 2 of 4 samples tested at a concentration of 250 ng/ml. In addition, 25% growth suppression was observed with a third sample tested, and no growth suppression was observed in 1 sample. Thus, clonogenic melanoma cells are sensitive in vitro to the cytotoxic activity of this immunotoxin at concentrations which we presume are pharmacologically relevant.     

Pyrolysis of precambrian kerogens: Constraints and capabilities

Summary Precambrian kerogens are currently considered to be the primary candidates for the search of biochemical fossils. Degradation of kerogens by relatively mild pyrolysis techniques, such as under high vacuum, can liberate indicative structural moieties which were incorporated in, and perhaps shielded by, these solid and highly condensed, basically aromatic substances. It is necessary to observe analytical constraints (sample size and shape, temperature, pressure, time, etc.) in order to prevent an overabundant yield of secondary pyrolyzates (inter- and intramolecular rearrangements) which can prevent kerogen characterization. Potential biochemical fossils have been found in Precambrian kerogens. Demonstratable syngenetic biochemical fossils are expected after kerogen diagenesis and catagenesis is understood in sufficient detail, and when pyrolysis is augmented by multiple, improved analytical techniques.Dedicated to the Memory of H.C. Urey (1893–1981)     

α-methyl-6-aminodopamine: Depletion of catecholamines in mouse brain and peripheral tissues

A new synthetic agent R, S-2-amino-1(2-amino-4, 5-dihydroxyphenyl) propane dihydrobromide, also referred to as α-methyl-6-aminodopamine (α-Me-6-ADA), has been found to produce acute (one day) and longer-term (seven day) depletion of norepinephrine (NE) levels in mouse brain and peripheral tissues. A 100 mg/kg dose of α-Me-6-ADA (i.v., free base) produced greater than 85% depletion of NE in the heart and spleen at one day and one week after treatment. Intracranially, α-Me-6-ADA (100 μg i.vtr.) depleted NE in the telencephalon and brain stem by 79% and 21% respectively at seven days. In addition DA was depleted by 45% in the ipsilateral striatum. The α-Me-6-ADA appears to have a relative selectivity for noradrenergic nerves, as an intracranial dose of 10 μg, which decreased NE in mouse whole brain by 52% at one day, failed to alter the DA content. These data suggest that α-Me-6-ADA may be a neurotoxin.     

Radioimmunoassay for the detection and quantitation of bruceantin

A radioimmunoassay for a new anticancer drug, bruceantin, has been developed using [³H]acetylbruceantin and antibody induced by immunizing rabbits with succinylbruceantin-bovine serum albumin conjugates. [³H]Acetylbruceantin was synthesized by reacting bruceantin with [³H]acetyl anhydride. The assay is simple and reproducible. The standard curve was linear on a logit-log plot, and the lower limit of sensitivity of the assay was 1 ng/ml. Using this assay, drug levels were easily determined in tissues of experimental animals following bruceantin administration. The assay procedure does not require sample extraction for plasma, urine, and bile. Bruceantin in other tissues can be extracted quantitatively with ethanol before being measured by the radioimmunoassay.