No abstract

No abstract

Treatment of mouse (Ehrlich ascites tumor and L929) and human (FS4, GM258, etc.) cells with homologous interferons results in the induction of several proteins. Extracts obtained from cells labeled with [35Simethionine in the absence or presence of interferon were fractionated on poly(I)poly(Cagarose columns. The proteins retained on the columns revealed, upon sodium dodecyl sulfate/polyacrylamide gel electrophoresis, three protein bands in mouse cells (Mr 120,000; 80,000; and 67,000) and two in human cells (Mr 120,000 and 80,000) which were detected in the extracts of interferon-treated but not of untreated cells. These proteins were retained on double-stranded RNA [poly(I)poly(C)agarosej columns but very poorly, if at all, on single-stranded RNA [poly(I) or poly(C)agaroseJ columns, suggesting that they have an affinity for double-stranded RNA. In addition, interferon treatment of human fibroblasts greatly increased the labeling of three other protein bands (Mr 88,000; 67,000; and 56,000) which were detected in whole extracts but were not appreciably retained on poly(I).poly(C)agarose columns. The appearance of the induced proteins was blocked by actinomycin D if added together with interferon, indicating that transcription of certain genetic information is required. The possible correlation between the induced proteins described here and the elevated levels of certain enzymes in interferontreated cells (a protein kinase and 2'-5'-oligoadenylate synthetase) is at present unclear.Interferons are known for their potent antiviral activity. The replication of a wide variety of RNA and DNA viruses is blocked in cells pretreated with interferon (1, 2). Interferon treatment also results in various other effects, such as: alterations at the cell surface, inhibition of cell multiplication, antitumor effects in experimental animals and in man, effects on immune functions, etc. (3, 4). The mechanism(s) whereby interferon treatment results in various biological effects remains to be elucidated.The establishment of the antiviral effect of interferon is blocked by actinomycin D (5-7) and by inhibitors of protein synthesis (6-8), suggesting that the expression of certain cellular genetic information is required. This is supported by experiments showing that enucleated cells fail to develop an antiviral effect upon interferon treatment (9, 10). Studies from various laboratories have revealed that the level of at least two enzymes is greatly elevated in various cell types upon interferon treatment. These are: (i) a protein kinase(s) which, in the presence of ATP and double-stranded (ds) RNA, phosphorylates at least two proteins of Mrs 64,000-67,000 and 35,000-38,000, and histones (11-14). The Mr 35,000-38,000 protein appears to be the small subunit of the initiation factor eIF-2 required for protein synthesis (15, 16). (ii) The other is an enzyme (2'-5'-oligoadenylate synthetase) which synthesizes 2'-5'-linked oligoadenylates with the structure pppA(2'p5'A)n from ATP in the presence of ds RNA (17, 18). These oligonucle...

Characteristics of inaccessible respondents in a telephone survey were investigated. City employees (N = 514) of San Antonio, Texas, answered a series of questions on birth date, employment, seniority, monthly salary, occupation, and 18-year old voters. Refusal rates were examined across ethnicity, salary, and age with the highest rate occurring for the oldest age group. Overall percentage of refusals (10.9) and pattern of refusals by age were similar to those of face-to-face surveys. An analysis of inaccessible black respondents (refusers and those not reached, n -140) indicated an unusually high inaccessibility rate (42%). Neither refusals nor inaccessibility resulted in large differences between the distributions of persons contacted and persons interviewed. Thus, the chance of bias in the survey responses seems minimal.