[Expected risk of congenital toxoplasmosis in Florence and its province. Statistical research in 1984]. / Rischio atteso di toxoplasmosi connatale in Firenze e provincia. Ricerca statistica nell'anno 1984.

Research has been carried out to determine the prevalence of toxoplasma infection in 1176 women of fertile age in Florence and province for 1984 so as to calculate expected congenital foetal risk of toxoplasmosis. Prevalence proved to be 22% in women aged from 15 to 20 and 60% in the 41-45 group, with an average annual sero-conversion rate of 1.5%. As pregnancy lasts 9 months, this rate is cut by 1/4, namely it drops from 1.5% to 1.125%. Transmission of the infection from mother to foetus occurs in about 1/3 of cases. 9256 pregnancies were reported in Florence and province. The expectation was therefore 104 primary infections and 35 infected newborns of whom 11-12 clinically diagnosable at birth. The estimated rate of toxoplasmosis in pregnancy is therefore 11% for Florence and foetal infection is about 4%. Two-thirds of the newborns with toxoplasma infection are asymptomatic but, if left untreated, they may develop serious neurological and behavioural sequelae. It is therefore necessary to learn the immune state with respect to toxoplasma for all fertile women before pregnancy and study negative findings during gestation.

Initial assessment of the performance of an 0.3 T permanent magnet in whole body NMR imaging.

An 0.3 Tesla permanent magnet was constructed and incorporated into a complete whole body NMR imager. Axial, sagittal and coronal images from human subjects were obtained using a two-dimensional Fourier Transform analysis of selected planes 8 mm thick, combined with an efficient multislice technique that produces sections centered 12 mm apart. Images were obtained based on inversion recovery and spin echo modes. The permanent magnetic field is uniform to 10 ppm over 38 cm. The magnet requires no special maintenance and has an extremely small fringe field. The magnet design, with its field vertical to the long axis of the subject, permits use of a solenoidal radiofrequency receiving coil for optimal signal-to-noise ratio. Images were shown that are of high quality and produced under conditions simulating those necessary for efficient patient throughout in a clinical setting. Many of the unique features of NMR imaging, such as ability to directly obtain axial, sagittal and coronal projections, the variety of imaging modes, the natural sources of contrast, and the ability to visualize clearly medium and large blood vessels, were demonstrated.

Structural studies of natural actomyosin from thermally acclimated frogs.

Natural actomyosin was isolated from skeletal muscle of frogs (Rana catesbeiana) acclimated at 25 degrees C and 5 degrees C. It was found that preparations isolated from warm-acclimated frogs may display considerable degradation of myosin heavy chains as compared with preparations isolated from cold-acclimated frogs. However, degradation may be minimized by inclusion of protease inhibitors during purification, indicating enhanced protease activity in preparations of natural actomyosin from warm-acclimated frogs. When purified in the presence of protease inhibitors, natural actomyosin from both warm-acclimated and cold-acclimated frogs exhibits comparable subunit composition of SDS-gel electrophoresis. The overall gel pattern is similar to that obtained from rabbit natural actomyosin except that in the frog, troponin-T and troponin-C appear to co-migrate with tropomyosin and myosin light chain 2, respectively.

Structural properties of frog muscle myosin.

Frog myosin is a labile molecule, undergoing irreversible aggregation and rapid loss of ATPase; however, a procedure is described which provides highly purified myosin, with stable solubility and enzymatic properties, from skeletal muscle of Rana catesbeiana. Frog myosin contains heavy chains and light chains 1, 2, and 3. Light chain 3 is present in excess over light chain 1, and light chain 2 may occur as either, or both, of 2 closely migrating bands. On two-dimensional electrophoresis, light chain 1 generates an isoelectric component with pK 5.60; light chain 2 generates a complex pattern with 3 or 4 major components; and light chain 3 generates 2 major components with pK 5.00 and 4.92. The same subunit composition is obtained for frogs acclimated at 25 and 5 degrees C; however, proteolytic artifacts may occur in myosin preparations purified in the absence of protease inhibitors, especially in warm-acclimated frogs.

A new analytical procedure for two-dimensional electrophoresis of cellular proteins: comparison of protein compositions of parent strain and a K+-accumulation mutant of E. coli.

An improved two-dimensional analytical electrophoretic technique fractionates according to molecular weight in the presence of dedecyl sulfate in the first dimension, then fractionates according to isoelectric point in a perpendicular dimension. Electrofocusing in the second dimension achieves nearly complete removal of most protein components while providing true estimates of their isoelectric points. Because not all proteins penetrate isoelectric focusing gels, some proteins may go unrecognized using conventional two-dimensional systems where isoelectric focusing precedes electrophoresis. However, such components do enter dodecyl sulfate gels; hence the presence and molecular weight of those components can be established by the new procedure. A concurrent finding was that, in general, penetration of isoelectric focusing gels by discrete protein subunits dissolved in 9 M urea is an all-or-none phenomenon depending on the solubility of the specific subunit. The procedure was applied to comparison of the protein compositions of a parental strain (CBH) of Escherichia coli and a derived mutant strain (RD-2) deficient in ability to accumulate K+. The strains showed similar two-dimensional patterns except for one discrete isoelectric component absent in the parent strain but present in the mutant.