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The thermal denaturation of the A and B variants of bovine β-lactoglobulin has been examined using optical rotatory dispersion and sedimentation velocity techniques. An equation is derived which describes the time dependence of optical rotation in terms of parameters relevant to a system involving two consecutive first order reactions. Analysis of simulated and experimental curves according to the procedure of Guggenheim (Phil. Mag., 2 (1926) 538) suggests that two consecutive first order unfolding reactions dominate the early stages of the denaturation. Optical rotatory dispersion and circular dichroism analysis in the far ultraviolet region of the spectrum shows that there is a significant increase in the proportion of β-structure in the molecule on thermodenaturation. In addition, thermodenaturation causes an aggregation of the protein, the extent of which depends on both the time and temperature of heat treatment.

1-Phenethylbiguanide (DBI, phenformin) is an orally administered hypoglycemic agent which is not related to the sulfonylurea drugs.DBI has been effective in treating diabetic subjects who require small amounts of insulin and as an adjunct to insulin therapy in the labile diabetic patient; however, the high incidence of gastrointestinal side effects it produces limits its use.No systemic toxicity following administration of DBI has been noted in man.The authors present their experience with DBI in treating 49 patients, and describe current theories concerning its mechanism of action.

All who desire to be called teachers should be interested in con tinuous personal growth in their profession. To realize continuous growth teachers need access to self-evaluative techniques and super vision. Most teachers do not have adequate supervision; therefore, the need becomes paramount in importance for self-evaluative tech niques by which the school staff can improve themselves and the school program thereby.1

The assignment of the carbon-13 magnetic resonance spectrum of l -tryptophan in aqueous solution and in trifluoroacetic acid is made by comparison with the spectra of indoles, by double resonance and by deuteration experiments. On the basis of work on small peptides, it is possible to assign all the downfield resonances in denatured proteins to single types of carbon atoms, with the exception of the carbonyl carbons and the histidine Cγ resonance. In the upfield region there are only about eleven resonances which correspond to single types of carbon atoms from eight different amino acid residues. The spectra of a particular protein denatured by heat, 6 M guanidine · HCl or formic acid are all similar. The spectrum of a native protein is much broader than that of the denatured protein due to small differences in chemical shift which result from environmental changes of some carbon atoms, and line broadening due to decreased mobility of carbon atoms.

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The heat denaturation of lysozyme has been studied by proton magnetic resonance spectroscopy at 220 MHz in water at pH 2.8. At 20°C a broad resonance is observed at 6.8δ due to the arginine NH2resonances, which becomes a well defined triple resonance at 40°C, without any change in the rest of the spectrum. This sharpening of the arginine NH2resonances is due to their increased mobilities and/or some normalisation of their chemical shifts. It is proposed that the surface structure of lysozyme is loosened at 40°C, without any change in the hydrophobic core and this is considered to be an intermediate phase in its heat denaturation. The heat denatured product at 80°C in D2O retains some noncovalent interactions, since further treatment with guanidine deuterochloride or mercaptoethanol causes sharpening of the aromatic region of the spectrum.

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Sulfamethoxypyridazine (Kynex) has recently been introduced as a new antibacterial sulfonamide with good gastrointestinal absorption and prolonged action. It has been proposed for use both as a prophylactic agent and for the therapy of subacute or chronic infections where sulfonamides have previously been employed.1To date no reports of major toxic reactions to sulfamethoxypyridazine have been noted in the literature. It is the purpose of this report to present two cases of severe toxicity with predominantly hematological manifestations secondary to sulfamethoxypyridazine. Report of Cases Case 1.— A 36-year-old housewife noted headache, heavy yellow postnasal drip, and fever on June 13, 1957. Two days later her private physician started therapy with sulfamethoxypyridazine, 0.5 Gm. twice a day. A total of 15 tablets were taken in seven and one-half days. On the eighth day the patient observed a "rash" and that evening vomited "coffee ground" material. The following day the rash

SummaryRibonuclease-treated homogenates of liver that do not incorporate mevalonic acid into non-saponifiable material or cholesterol were devoid of ATP. ATP was present and mevalonic acid incorporation occurred when ribonuclease pretreatment was carried out in presence of an autoclaved extract of liver. The results are interpreted as indicating existence of a polynucleotide factor essential for maintenance of a positive balance with respect to ATP in liver homogenates.

The beam-following study was devoted to bracketing improvement and noise reduction. Nonlinear systems in the bracketing-improvement study were investigated in which: (1) the system gain was a nonlinear function of the coupler output, (2) the time constant of the lead network was a function of the distance from the localizer transmitter, and (3) a beam position sensor automatically engaged at the moment the rate signal became larger than the displacement signal. Typical REAC solutions are included. A perception filter characterized as a low-pass filter with a variable cut-off frequency and a controlled limit on the second-derivative of the output was developed in the nonlinear program for minimizing beam-noise effects on the ILS-A/P-A/C control system. Data taken on the REAC are presented as evidence that the performance of passive (RC) integrators in a second-order low-pass filter with limiting on the second derivative of the output is similar to corresponding portion of the perception filter.