Estimating the prevalence of dental phobias.

This paper estimates the prevalence of dental phobias in the community. Information collected from diverse sources yields a rate for dental phobias within the range 10-14 per cent. It is concluded that the difficulty experienced in obtaining subjects/clients to undertake remedial programmes to overcome dental fear is not due to a shortage of such phobics in the community at large.

Preparation of human immunoglobulin by caprylic acid precipitation.

Caprylic acid was used to precipitate nonimmunoglobulin proteins from human plasma. The crude IgG present in the supernatant (which contained 26-29% of the total protein in terms of absorbance units or 78-87% of IgG by weight) was fractionated on DEAE-cellulose, to yield pure IgG as shown by disc electrophoresis, immunoelectrophoresis and gel filtration. Pure IgG was free of plasmin and plasminogen and did not exhibit any fragmentation or aggregation during storage for periods up to 4 weeks at 40 degrees C, and its anticomplementary activity was low. Antibodies to viral agents were recovered unchanged.

Preparation of human immunoglobulin free of plasmin and anticomplement activities.

Human IgG separated by Cohn fractionation showed variability in the content of aggregates, plasminogen and anticomplement activity. The plasminogen was removed or markedly reduced by affinity chromatography on Sepharose-lysine. Anticomplement activity was reduced by chromatography of Cohn fraction II on DEAE-cellulose. Preparations of IgG obtained by chromatography of intermediates from Cohn fractionation (e.g. Cohn FII + FIII or FII + FIII W) on DEAE-cellulose were devoid of aggregates, plasminogen and exhibited reduced anticomplement activity. The initial levels of specific antibody activity to viral agents were recovered in the IgG fractions. Fragmentation of IgG during storage was prevented or greatly reduced by removal of plasminogen by affinity chromatography on Sepharose-lysine.

Some biological and physical properties of molluscum contagiosum virus propagated in cell culture.

Molluscum contagiosum virus propagated in FL cells of human amnion origin has a one-step growth cycle time of 12 to 14 h. The appearance and exponential increase of intracellular virus preceded the release of extracellular virus by approximately 2 h. Demonstration of comparable titers of extracellular and intracellular virus at the end of the replication cycle indicated that a substantial amount of virus remained associated with cells exhibiting cytopathogenic changes. Mean buoyant density values of virus in sucrose ranged from 1.275 to 1.278 g/cm3, but in CsCl the virus banded at densities at 1.325 to 1.340 and 1.261 to 1.281 g/cm3. Although virus infectivity was not affected by high concentrations of CsCl, it was found by polyacrylamide gel electrophoresis that the salt removed several nonglycosylated polypeptides with estimated molecular weights of 15,000 to 60,000. This suggested that the high-density band (1.325 to 1.340) may reflect the loss of these structural components. The half-life of virus infectivity was approximately 26.5 h at 26 degrees C and 11.2 h at 37 degrees C. Although the virus was rapidly inactivated at 50 degrees C, it could be stabilized at this temperature by the presence of 1.0 M MgCl2. Virus did not agglutinate newborn chick, adult chicken, or type "0" human erythrocytes. Virus infectivity was found to be sensitive to acid pH but resistant to treatment with diethyl ether or chloroform. The replication of molluscum virus in FL cells was not inhibited by 5-iodo-2'-deoxyuridine, 5-bromo-2'-deoxyuridine, or cytosine arabinonucleoside in noncytotoxic concentrations of 200 to 400 mug/ml, but greater than 99% reduction in the yield of herpes simplex virus or vaccinia virus in FL cells was obtained with 200 mug of these compounds per ml. Guanidinium chloride in concentrations of 100 to 200 mug/ml reduced molluscum virus yields by more than 99.9%.

Preparation of human immunoglobulin by ammonium sulfate precipitation.

Crude IgG precipitated from plasma by the addition of an equal volume of 4 M ammonium sulfate was fractionated on DEAE-cellulose column to obtain pure IgG as shown by disc electrophoresis, immunoelectrophoresis and gel filtration. The processed IgG was free of plasmin and plasminogen and did not undergo fragmentation or aggregation on storage at 40 degrees C for at least 4 weeks. The anticomplement activity was low and the antibody activity was retained.