Resolving multiple overlapping calorimetric transitions by use of a microcomputer: studies on erythrocyte membranes

Buffer changes and certain drugs cause temperature shifts, amplitude changes, and transition broadening in the differential scanning calorimetric (DSC) analysis of erythrocyte membranes. However, it has been difficult to interpret and quantitate these shifts and changes because the scans are composed of multiple overlapping transitions and because more than one transition may be simultaneously affected. An empirical approach has been developed by using Gaussian modeling to resolve these calorimetric transitions. Data analysis was carried out on a microcomputer using a nonlinear regression program (PCNONLIN) to fit the data scans. These results show that changes in the calorimetric scans of erythrocyte membranes due to alterations in the buffer environment, such as pH and osmolarity, can be resolved by fitting the data scans with the proposed mathematical model and optimizing the resolution parameters with PCNONLIN. In addition, resolution uncovered hidden characteristics that may not have been readily evident. Under certain conditions, for example, apparent transition shifts were shown to actually be amplitude changes and transition broadening. Determination of the limitations and validity of this method was accomplished with simulation studies. This technique offers a simple means for fitting overlapping DSC transitions by use of a commercially available nonlinear regression program that can be run on a microcomputer.     

Studies on the syntheses of hydrogenated quinolines and isoquinolines as analgesics—XVII The steric structure of N-methyl-8-aza-des-N-morphinan

The configuration of positions 13 and 14 in N-methyl-8-aza-des-N-morphinan has been investigated. Potassium t-but-oxide in t-butanol converts N-acetyl-10-oxo-8-aza-des-N-morphinan (XVI) into 10-hydroxy-8,10-(-oxo-ethano)-8-aza-des-N-morphinan (XVII). Formation of these new lactams is possible only when rings B and C are cis. It follows, therefore, that 8-aza-des-N-morphinan synthesized in this investigation has B/C in cis and C/D in trans positions the same as the steric structure of morphinan (M).     

1,1-bis(trimethylsilyl)-1-alkanols as silylcarbene equivalent

Silylcarbenes are generated by the pyrolysis of 1,1-bis(trimethylsilyl)-1-alkanols with elimination of trimethylsilanol.     

Dual-basis orthonormality-constrained variation method

The method of orthonormality-constrained variation is extended using a dual-basis set instead of a single orthonormal basis. The complete and the partial variation methods are discussed and applied to electronic systems. It is found that the present formulation leads to the most general equation in the coupling operator method.     

Four-m calculations on methanol-water solutions

The structural characteristics of methanol in aqueous solutions, on a molecular level, can be elucidated by four types of calculation: molecular orbital, multiparametric optimization of intermolecular potential function, Monte Carlo, and molecular dynamics. As a first step, the potential between water and methanol was determined by ab initio LCAO SCF molecular orbital calculations with the STO—3G basis set and subsequent multiparametric fitting. This and water—water potentials were used for Monte Carlo calculation on an aqueous methanol solution containing a 1:216 mole ratio of methanol to water. Hydration around methanol is briefly discussed.     

Anti-inflammatory activity of new guaiane type sesquiterpene from Wikstroemia indica

In our investigation of in vitro anti-allergic screening of medicinal herbal extracts, the ethyl acetate extract of the root of Wikstroemia indica was observed to inhibit nitric oxide (NO) production in a lipopolysaccharide (LPS) and recombinant mouse interferon-gamma (IFN-gamma) activated murine macrophage-like cell line, RAW 264.7. Fractionation of the active extract led to the isolation of one new guaiane type sesquiterpene, indicanone (1), and two known biflavonoids, sikokianin B (2) and sikokianin C (3). 1 inhibited NO production with IC50 values at 9.3 microM and also inhibit the inducible nitric oxide synhase (iNOS) gene expression. This is the first report of NO production inhibitory activity of Wikstroemia indica and supports the pharmacological use of it, which has been employed as an herbal medicine for the treatment of inflammation.     

Study on tumor affinity of technetium-99m-labeled radiopharmaceuticals. (2) 99mTc-Sn-diphosphonate (99mTc-EHDP), 99mTc-Sn-dimercaptosuccinic acid (99mTc-DMSA), and 99mTc-Sn-diethyl stilbestrol diphosphate (99mTc-DSDP)]

The authors have examined the tumor affinity of various 99mTc-labelled radiopharmaceuticals to Ehrlich's tumor for the purpose of delineating positively human malignant neoplasm. This paper includes biologic distributions of 99mTc-Sn-diphosphonate (99mTc-EHDP), 99mTc-Sn-dimercaptosuccinic acid (99mTc-DMSA) and 99mTc-Sn-diethyl stilbestrol diphosphate (99mTc-DSDP, 99mTc-Honvan) as the second report on the tumor affinity to the Ehrlich-bearing mice. (a) Tumor concentration of 99mTc-EHDP was lowest and the positive delineation of implanted tumor with 99mTc-EHDP was poorest in sequential images, though the active accumulation to some soft tissue maglinant neoplasms, the breast cancer and the thyroid cancer, has been reported. (b) Tumor concentration and tumor to blood ratio of 99mTc-DMSA were not so high on the contrary of our expectation that 197Hg-DMSA may show the high tumor concentration and the high tumor to blood ratio like 197Hg chlormerodrin as same renal scanning radiopharmaceuticals. (c) Tumor concentration of 99mTc-DSDP was highest. Tumor to blood concentration ratio, however, was lower than that of the above mentioned radiopharmaceuticals but tumor to liver ratio and/or tumor to lung ratio was over 1.0 at the earlier time. Biologic distribution of 99mTc-DSDP was similar to that of 32P labeled DSDP and then it is presumed that 99mTc is labeled at phosphate ester of DSDP which is dephospholytated immediately by phospholylase in vivo following the intravenous injection. Therefore, it may be assumed that the accumulation mechanism of 99mTc-DSDP to Ehrlich's tumor is related to the phospholylase activity in neoplasms but is not known precisely.     

Application and limitation of a mathematical distortion model of an absorbance signal in electrothermal atomic absorption spectrometry

A distortion model of instrumental function is described, based on the response signal. Its limitations are investigated by using quasi-signals generated by an oscillator and a moving carbon rod.     

Periodate oxidation analysis of carbohydrates: Part IV. Simultaneous determination of aldehydes in di-aldehyde fragments as 2,4-dinitrophenylhydrazones by thin-layer or liquid chromatography

A method for the simultaneous determination of aldehydes in dialdehyde fragments, obtained from carbohydrate samples by periodate oxidation, is proposed. Reaction mixtures obtained from the periodate oxidation of carbohydrate samples are deionized by resins, and evaporated to dryness. The syrupy residues are treated with 2,4-dinitrophenylhydrazine hydrochloride in 1.2-dimethoxyethane at 25°C for 3 h. The resultant mixtures of hydrazones are separated by t.l.c. or l.c., and individual hydrazones are determined by spectrophotometric measurement. Reliable analyses of carbohydrate linkages are possible with 50–250-μg samples.     

Dilatometric study of monovalent counter-ion association with carboxylates

Volume changes accompanying the protonation of mono-, di- and poly-carboxylates in water were measured at 25° using the circulation dilatometer. The carboxylates include alkali metal and tetra-alkylammonium (TAA) salts of acetic, pivalic, glutaric acid and samples of poly(methacrylic acid) (PMA) having various molecular weights and degrees of stereoregularity. It was found that TAA counter-cation exerts specific influence on the differential molar volume change on protonation of the pivalate and PMA in contrast to the absence of such specificity in the corresponding alkali metal salts. These results were interpreted by the proposed association of the hydrophobic ammonium cation with the carboxylate anions. Volume contraction is accompanied by the association. It was also proposed, on the basis of these findings, that alkali metal counter-ion is not likely to be ‘site bound’ by the respective charges of PMA. PMA configuration has a minor effect on the volume change.