Evaluation of methods using adherence to substrate and density gradient for the isolation of human monocytes.

A new method for monocyte isolation based on cell adherence to gelatin-coated plastic and dislodgement of the adhering monocytes at low temperature was compared with 5 other methods based on cell adherence to substrate and density gradient separation. All methods produced yields of monocytes ranging approximately between 50-70% with about the same degree of purity (less than 90%) except for the method using Percoll density gradient centrifugation where the purity of monocytes was about 80%. When lidocaine at different concentrations was used for cell dislodgement or Percoll density gradient for separation, phagocytosis, Fc receptor function and cytotoxicity were adversely affected, unlike in methods using EDTA or low temperature for dislodgement of the adherent cells. In monocyte chemotaxis assays the rate of migration was affected but not the number of migrating cells for all the isolation procedures investigated. Cell spreading function was apparently well maintained only when gelatin coated plastic was used for adherence and low temperature for cell dislodgement. These data indicate that the newly described method, similar to methods using EDTA for cell dislodgement, yielded relatively intact monocytes but unlike the latter method with better preserved cell spreading. Thus, this method can be considered for standardization to obtain pure monocyte populations from peripheral blood which then can be submitted for comprehensive biochemical and physiologic studies.

Viral hepatitis and hydraulic parameters: an alternative hypothesis.

Point source outbreaks of viral hepatitis have been associated with the consumption of contaminated food and water, yet epidemiologic analysis of the disease in the general population usually provides strong correlations with sub-standard socioeconomic conditions. However, statistical analysis of municipal public health records in Worcester, Massachusetts showed that significant correlations existed between the incidence of viral hepatitis and certain water and sewer parameters. A 5-yr period spanning the epidemic outbreak of 1969 to 1970 was analyzed. Significantly higher incidences of the disease occurred in those areas of the city served by old water and sewer pipes, combined sewers and the low pressure water distribution system. Based on this epidemiologic evidence, the authors propose that an alternate hypothesis, based on hydraulic arguments, can be made which will explain the observations. Although neither hypothesis, socioeconomic or hydraulic, can be excluded solely on the basis of epidemiologic results, this new hypothesis may prove useful in the design of methods for environmental control of viral hepatitis.

The reappearance of a classical epidemic of infectious hepatitis in Worcester, Massachusetts.

Worcester, MA, experienced an outbreak of hepatitis during 1969-1970, an expected event which had occurred previously at eight-year intervals since reporting of the disease began in 1950. Other Massachusetts communities of similar character and the nation did not experience an epidemic during that same period. An extensive epidemiologic study of the disease illustrated that the epidemic followed the classical pattern in which individuals 5-14 years old were most affected irrespective of sex. During the interepidemic years from 1968-1972 in Worcester, and in all years (1968-1972) in both New Bedford and Springfield, MA, those primarily affected were young adults 15-30 years old, with male cases predominating. Sociodemographic statistical analyses also indicated the classical pattern of the less affluent, less educated, and sometimes the more crowded populations being at greater risk of contracting the disease. This outbreak of hepatitis was comparable to another in Greenland two years later in which immunologic methods differentiated between type A and type B viral infections. The data from both studies support the conclusion that the type B virus, often associated with parenteral drug use, is the predominate infectious agent during the interepidemic (endemic) periods. The type A virus is most likely responsible for the periodic epidemics.

Effect of procaine HCLl on ATP: calcium-dependent alterations in red cell shape and deformability.

Procaine hydrochloric acid, a cationic anesthetic, although unable to prevent the effect of calcium ionophore A23187 on erythrocytes, inhibited the discocyte--echinocyte transformation, increased viscosity, and decreased filterability of red cells undergoing ATP depletion. The effects were abolished by washing ATP-depleted, procaine HCl-treated red cells prior to these determinations. Procaine HCl had no effects on volume, incubated osmotic fragility, or monovalent cation composition of ATP-depleted red cells. The drug increased 45Ca uptake by ATP-depleted red cells but did not change the fraction of membrane-bound calcium. Sodium dodecyl sulfate acrylamide gel electrophoresis of membrane proteins from ATP-depleted red cells revealed formation of high molecular weight protein complexes, which were not formed when biconcave shape and ATP content were maintained by incubation with adenine (0.54 mM) and inosine (12.7 mM); Formation of these complexes was not prevented when the biconcave shape was maintained by procaine HCl. It was concluded that the maintenance of the biconcave shape and normal deformability during ATP depletion by procaine HCl was not related to a displacement of membrane-bound calcium and inhibition of ATP-dependent rearrangement of red cell membrane proteins.