M. van Sande

A new ordered phase in the AlPd system

Abstract Using electron diffraction and electron microscopy a new phase has been observed in a rapidly solidified Al-6%Pd alloy. Depending on the cooling rate this phase is present in the as quenched cellular-dentritic structure along the cell boundaries or in finer precipitates mostly along the domain boundaries of the fcc solid solution. In both cases the precipitates agglomerate and grow to bigger size after heating in the electron microscope. The new phase having a complicated structure and a large unit cell is closely related to the Al 4 Mn phase which is hexagonal.

Proteases and their inhibitors: today and tomorrow

A major incentive in inhibitor research is that control of limited proteolysis constitutes a valuable pharmacological tool. Protease inhibitors have proved to be successful in influencing pathogenesis in many experimental models but a breakthrough to use in human therapy has mainly been restricted to aprotinin and angiotensin converting enzyme (ACE) inhibitors. However, the success of ACE inhibitors as pharmacological tools in hypertension has proved to be a strong stimulant for new protease inhibitor approaches to drug therapy. While emphasis in the search for next generations of ACE inhibitors may move from the circulation renin-angiotensin system to the local tissue systems, including heart, brain and genital tract, persistent and insightful design of renin inhibitors has already yielded highly specific molecules with potent activities in several in vivo models. The development of orally effective long-acting inhibitors will finally allow an evaluation to be made of their therapeutic profile with regard to the family of ACE inhibitors. The close relationship between renin and HIV-1 protease presents an exceptional opportunity for transfer of the knowledge acquired in renin inhibitor development during the past decade, to an accelerated generation of specific HIV-1 protease inhibitors as effective agents in treatment of AIDS. The self-assembly of 2 identical monomers into a symmetrical structure in HIV-1 protease is not only an elegant way to create an active enzyme while encoding a minimal amount of genetic information, but is also in concordance with the bilobular active-site found in mammalian aspartic proteases.(ABSTRACT TRUNCATED AT 250 WORDS)

Aminopeptidase P and dipeptidyl peptidase IV activity in human leukocytes and in stimulated lymphocytes

Human white blood cells were shown to contain high aminopeptidase P activity. The specific activities found in the high-speed supernatant of the extracts of granulocytes, lymphocytes and monocytes ranged from 30 to 70 units per mg protein. Culturing lymphocytes during 7 days in the presence of phytohaemagglutinin resulted in a 70-200% increase in the specific aminopeptidase P activity and a 200% increase in the specific activity of dipeptidyl peptidase IV. The time-course of the activity of both aminopeptidase P and dipeptidyl peptidase IV during the stimulation of human T-lymphocytes by phytohaemagglutinin indicates an involvement of these two enzymes in the proliferative process of these immunocompetent cells. Due to their substrate specificity their potential substrates must have the N-terminal Xaa-Pro sequence known to be present in several immunologically important polypeptides.

A reinvestigation of the γ phase in CuAl alloys: a new long-period superstructure

Abstract In the CuAl system for aluminium concentrations between 30.8 and 40.9 at.% several structures occur which are related to the γ-brass structure. Electron microscopy, electron diffraction and high resolution imaging techniques were used to analyse these phases; apart from the previously described P- and R-type γ-brass phases a new long-period inversion boundary superstructure was discovered. This new phase was observed for alloy compositions intermediate between those corresponding to P-type and R-type γ-brass. Cooling experiments were performed to investigate the stability of this superstructure at room temperature. It was observed that after very slow cooling from 700 °C to room temperature a decomposition into P- and R-type γ-brass occurred. The results are discussed in terms of the stability of the γ-brass and related structures.

Méthode de dosage de l'haptoglobine des liquides biologiques par électrophorèse en gel de gélose et valeurs obtenues chez des sujets normaux

Abstract An electrophoretic method for the determination of haptoglobin concentration in biological fluids is described ; it makes use of the agar-gel electrophoretic technique devised by Wieme. It gives as accurate and reproducible results as the Laurell and Nymans filter-paper method, generally considered as the electrophoretic reference method. This agar-gel technique is much more rapid and allows to perform serial determinations. The results of 160 determinations made on sera of normal subjects are reported. The mean normal values are different according to sex and haptoglobin type.

Protéinogrammes et enzymogrammes des protéines musculaires en pathologie humaine

Abstract By electrophoresis in agar a study was made of the water-soluble proteins and lactate dehydrogenase of the muscular tissue in 33 fragments of human muscles obtained by biopsy or autopsy. Normal subjects, myopathies, cases of Steinerts disease and of neurogenic amyotrophia were studied and the results compared. The proteinograms make it possible to confirm that alterations are observed in albumen and m globulins which are characteristic of the muscular tissue. The alterations are especially marked in Steinerts disease, they are relatively less marked in neurogenic amyotrophia. The fastest globulin fraction seems to be also the most resistant to the alterations observed. In the enzymograms of lactate dehydrogenase, the alterations observed in myogenic and neurogenic amyotrophias are alike. In Steinerts disease the results obtained are practically normal.

Alpha1-antitrypsin, alpha2-macroglobulin and complement C4 in human benign prostatic hyperplasia

SummaryThe concentrations of the globulins α1-antitrypsin, α2-macroglobulin and complement C4 have been determined in tissue samples of benign prostatic hyperplasia, from patients with and without prior treatment before open surgery. Globulins have been determined by means of radial immunodiffusion. Results obtained show that α1-antitrypsin is present in high concentrations in human prostate. Treatment with anti-androgens influences the α2-macroglobulin concentration in the different prostatic lobes. Complement C4 concentration is not influenced by the treatment.

Distribution de deux peptides de l'acide γ-aminobutyrique dans le liquide céphalo-rachidien et le cerveau humains

Abstract The distribution of two peptides of γ-aminobutyric acid, homocarnosine and α-(γ-aminobutyryl)-lysine, was studied in human brain and cerebrospinal fluid. Adult brain and cerebrospinal fluid α- (γ-aminobutyryl) -lysine levels and adult brain homocarnosine levels are higher than those found in children. On the other hand, it is known that the cerebrospinal fluid from children contains higher concentrations of homocarnosine than those observed in adults. There exists a significant correlation between the levels of these two dipeptides in biopsied cerebral tissue.

Experimental evidence for pretransitional fluctuations and domain movements

A review is given of the observation techniques by electron microscopy and electron diffraction which allow information to be obtained on phase transitions and pretransitional phenomena in solids. The review is illustrated with a few examples of different types of transitions. The α→ β phase transition in quartz is discussed in some more detail. It is shown that in this case defect mobility is responsible for the observed pretransitional phenomena. Observations are reported of shimmering phenomena in two alloy systems: CuZnAl and a γ-brass (Cu4A19). The experimental conditions of appearance of the phenomena in these different systems are compared and related with possible physical origins.

Lipids in human benign prostatic hypertrophy

SummaryLipids in human prostate have been the subject of limited research and the most complete studies were published forty years ago. In this study we report on the total lipid, total cholesterol, free cholesterol and triglyceride content in human benign prostatic hypertrophy. By means of thin-layer chromatography, we separated the cholesterolesters in five fractions. The effect of treatment with anti-androgens before prostatectomy was examined.