Collecting and processing records from the ultracentrifuge in "real-time" using an on-line computer

An analytical system consisting of an analytical cantrifuge coupled 'on-line' to a computer was assembled and tested. Collection of records from up to 9 solutions was achieved through programmes which sum readings to reduce noise as well as controlling the positioning of the scanner. With this system it was found that the limit on accuracy for molecular weights at concentrations less than 0.01 g cm-3 was +/- 3% estimated from sedimentation equilibrium experiments. The same system was used to collect records for similar concentrations from velocity experiments by employing a scanning schlieren. In this case the accuracy in estimating sedimentation coefficients was similar to those found when measuring photographs. Since the collection yields detailed information about the shape of the sedimenting boundary, the centroids of the boundary were routinely computed by second moment analysis rather than relying on the position of the maximum of the schlieren peak. In the same analysis estimates of diffusion coefficients were made routinely by calculating corrected height/area ratios for each scan. These calculations were made during the real-time of the experiment, so making available molecular parameters rather than records which must be evaluated some time after stopping the experiment.     

Ethoxylation of fatty amines

It is well known that long chain alcohols and phenols cannot react with ethylene oxide in the absence of catalysts, whereas primary fatty amines can take up at least two moles of oxide to form tertiary amines. It has been found that further ethoxylation of this two mole adduct in the absence of added catalyst can proceed only if ethoxylation temperatures are lowered considerably. The present paper demonstrates that this low-temperature ethoxylation is really catalyzed by a previously overlooked highly alkaline compound generated during the course of the reaction. It is shown that this is a long-chain quaternary ammonium compound, and the mechanism of its formation is described. As the addition of ethylene oxide proceeds, this quaternary gradually decomposes and the reaction essentially comes to a halt when it has all disappeared.     

Extensive restriction site polymorphism at the human phenylalanine hydroxylase locus and application in prenatal diagnosis of phenylketonuria

A total of 10 restriction site polymorphisms have been identified at the human phenylalanine hydroxylase locus using a full-length human phenylalanine hydroxylase cDNA clone as a hybridization probe to analyze human genomic DNA. These polymorphic patterns segregate in a Mendelian fashion and concordantly with the disease state in various PKU kindreds. The frequencies of the restriction site polymorphisms at the human phenylalanine hydroxylase locus among Caucasians are such that the observed heterozygosity in the population is 87.5%. Thus, most families with a history of classical phenylketonuria can take advantage of the genetic analysis for prenatal diagnosis and carrier detection of the hereditary disorder.     

Immunocytochemical studies on Schistosoma mansoni. II. Soluble cercarial antigens in cercarial and schistosomules

The localization of soluble, cercarial antigen preparation (CAP) in cercariae and schistosomules of Schistosoma mansoni was performed at the light and electron microscope levels using the unlabeled antibody method. Reaction produce was observed associated with the contents of the pre- and postacetabular glands and with the filamentous coat of mature cercariae. No reaction product was observed associated with the glycoacalyx of schistosomules. However, several schistosomules did retain remnants of their filamentous coats and reaction product was observed associated with those remains. CAP components were also observed in the area surrounding the intrasporocyst cercariae.     

Relaxation time and effective mass of ions in liquid helium

A measurement of momentum relaxation times for charged particles in liquid helium is reported. The method is to measure the change in the reflection coefficient of a microwave cavity caused by the admission of ions. The measured relaxation times can be combined with the known dc mobilities of the ions to yield values for the effective masses. Most extensive measurements were performed using positive ions in He II. A temperature-dependent effective mass, increasing from approximately 40 helium masses at 1.3 K to over twice this value near the lambda point is found. The data are shown to be consistent with the electrostriction model of the ion, including contributions to the mass from both normal and superfluid components. A core radius of approximately 6 Å is shown to account both for the mass and for the mobility in the viscous flow region. Data on the negative carrier near 1.8 K yield an effective mass of 100 to 200 helium masses, and are consistent with the bubble model. The radius implied both by the mass and an analysis of mobility data in the viscous flow regime is 14±3 Å, quite consistent with the value deduced from other measurements. A measurement on the positive carrier in saturated (NBP) helium vapor indicates a mass of 75±20 helium masses. Both the mass and the mobility of this carrier are consistent with a droplet of radius 11±2 Å forming on the ion. The theoretical droplet radius is 12.6 Å.This work was supported in part by the Air Force Office of Scientific Research, The U.S. Atomic Energy Commission, and Research Corporation.     

Very low birth weight children at school age: comparison of neonatal management methods

The outcome of 293 infants born to a geographically defined community and weighing 501-1500 g was investigated. Medical intervention in the newborn period had been avoided. Morbidity was assessed at school age. Of the infants, 236 had been live born in the labour ward of this hospital; of these, 117 (49.6%) died in the neonatal period, one (0.4%) died in the first year, four (1.7%) were untraced, 13 (5.5%) had major handicap, 29 (12.3%) had minor handicap, and 72 (30.5%) were considered to be normal. In terms of survival, handicap, and intellectual with that of infants born over the same period (1963-71) in areas where intensive methods of perinatal care were used. These results imply that postnatal survival and potential of infants of very low birth weight are by no means prejudiced when only experienced nursing care is available.     

Comparison of high-performance liquid chromatographic serum profiles of humans and dogs

The sera of 30 healthy male beagles were analyzed by reversed-phase high-performance liquid chromatography. The profiles were compared with those obtained from the sera of 30 healthy human donors. The chromatograms of each group were very reproducible; however, there were characteristic differences between the two groups. The compounds observed in both the human and canine profiles were identified as creatinine, uric acid, tyrosine, hypoxanthine, xanthine, kynurenine, inosine and tryptophan. Compounds present only in the canine profiles were identified as cytindine, riboflavin and 5-methyl-cytidine. Compounds present only in the human profiles include uridine, guanosine, hippuric acid and the dietary dependent compounds theobromine and caffeine. The compounds present in both human and canine sera were quantitated and compared statistically. The amounts of these compounds were very similar, except for uric acid.