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A fraction with lymphokine properties was isolated from supernatant medium of the continuous cultured human lymphoblast cell line, 1788. Culture medium containing 2% human serum was used for cell growth in order to minimize antigenicity of supernatant fractions isolated from the medium. The culture medium was passed through an Amicon XM-100 membrane, concentrated over a PM-10 membrane, lyophilized, and reconstituted to a final concentration of approximately 40:1. Studies in vivo and in vitro showed that the active fraction contained skin reactive factor (when injected intradermally into guinea pigs and humans), lymphotoxin, migration inhibition factor, chemotactic factor, and macrophage activation factor. This same preparation, when injected intralesionally into cutaneous tumors, induced an inflammatory reaction followed by tumor regression. The fraction confined between membranes of pore size 10,000-100,000 daltons was active in promoting tumor regression, while the fraction less than 10,000 daltons was inactive. Patients with skin lesions from metastatic carcinoma of the breast and other malignancies were studied, and 16 out of 30 treated lesions were judged to have undergone either complete or greater than 50% regression. Of these, 8 were biopsied before and after lymphokine injection, and 6 out of 9 were negative for tumor cells. Additional studies in vitro with material fractionated on Sephadex G-200 indicated that the macrophage-activating component binds to alpha-2 macroglobulin in the culture medium.

Mice were actively immunized against Friend leukemia virus tumorigenesis by vaccination with cell-free homogenates derived from infected splenocytes emulsified in Freund's adjuvant. Adoptive immunity was also achieved by transferring splenocytes from actively immunized donor animals intravenously into syngeneic recipient animals challenged with the virus. Furthermore, RNA-rich extracts derived from spleens of actively immunized donor animals were capable of transferring immunity to FLV leukemia when injected into recipient animals challenged with the virus. The "immune RNA," when incubated with normal splenocytes in vitro, followed by washing, resulted in a cell population that also induced adoptive immunity after transfer to normal animals challenged with virus either before, simultaneously with, or after injection of the treated splenocytes. RNase, but not DNase or other enzymes, inactivated the biologie activity of the protective RNA from immune donors. In addition, isogeneic mouse serum that contained neutralizing antibody to FLV also inhibited the protective effect of the specific RNA; sera from control mice immunized with unrelated antigens failed to neutralize the specific RNA. These results indicate that an RNA extract that contains a virus-associated or -induced antigen is formed in the spleens of actively immunized animals and possesses the ability to either directly induce protective immunity in recipient animals challenged with virus or, indirectly, to convert normal splenocytes in vitro to adoptively confer immunity to similar recipients. Further investigations concerning the mechanism by which such immunogenic RNA functions in vivo and in vitro, as well as the physicochemical nature of the RNA complex, especially that portion associated with the tumor virus-associated antigen, are needed.

In vitro incubation of isolated X. laevis oocytes with progesterone induces the specific labeling of proteins during maturation. They are detected as several discrete peaks with a double-labeling technique that involves the injection of [3H] leucine into hormone-treated and [14C] leucine into control cells. The peaks are separated by sodium dodecyl sulfate polyacrylamide gel electrophoresis. Identical proteins are obtained with two other steroids that provoke maturation and with p-chloromercuribenzoate. The same progesterone-induced proteins are observed even if oocytes have been treated with actinomycin D or ethidium bromide or have been enucleated. Cycloheximide suppresses the labeling of proteins that are induced by progesterone, if administered either at the time of radioactive amino acid exposure or after prelabeling the oocytes to determine whether the hormone-induced peaks are due to compartmental changes of the proteins. A cytoplasmic fraction, obtained from maturing oocytes before GVBD, promotes maturation when injected into resting oocytes and therefore contains an MPF. After this injection, GVBD occurs earlier than during incubation with progesterone and is accompanied by the formation of the same proteins and of MPF, both suppressed by cycloheximide. The possibility that MPF is an induced protein is then discussed. It has been also found that there is a decrease in membrane permeability, as evidenced by decreased leucine uptake into proteins of oocytes incubated in radioactive amino acids and exposed to progesterone. The same decrease occurs after injection of MPF-containing cytoplasm into oocytes.

Leucocyte migration inhibition detected in vitro by the capillary tube technique (LMCT) has proved a useful tool for detection of tumor-specific cell-mediated hypersensitivity (TCMH) in man. Investigations in pateints with renal tumors are reported. It is shown that TCMH is a feature of hypernephroma in man, that the antigenic specificity is found in autologous as well as allogeneic tumor tissue and in fetal kidney tissue. The pattern of reactivity compared to postoperative survival and occurrence of metastases and postoperative clinical course shows a clear association between TCMH and tumor elimination. The capacity of hypernephroma patients to develop a cell-mediated immune response is generally not reduced. In allogeneic combinations, small noninvading tumors usually have a high antigenicity, whereas tumors with early dispersion show a low antigenicity. The development of TCMH and associated tumor elimination therefore may be depending preferably on the antigenicity of the tumor, less on the immune capacity of the tumor host.

This paper considers neural representation through the lens of active inference, a normative framework for understanding brain function. It delves into how living organisms employ generative models to minimize the discrepancy between predictions and observations (as scored with variational free energy). The ensuing analysis suggests that the brain learns generative models to navigate the world adaptively, not (or not solely) to understand it. Different living organisms may possess an array of generative models, spanning from those that support action‐perception cycles to those that underwrite planning and imagination; namely, from explicit models that entail variables for predicting concurrent sensations, like objects, faces, or people—to action‐oriented models that predict action outcomes. It then elucidates how generative models and belief dynamics might link to neural representation and the implications of different types of generative models for understanding an agent's cognitive capabilities in relation to its ecological niche. The paper concludes with open questions regarding the evolution of generative models and the development of advanced cognitive abilities—and the gradual transition from pragmatic to detached neural representations. The analysis on offer foregrounds the diverse roles that generative models play in cognitive processes and the evolution of neural representation. [ABSTRACT FROM AUTHOR]

Parnia et al. recently published suggestions for the study of death and experiences recalled in a near‐death context. We have serious reservations about the authors' statements. In this commentary, we discuss the omissions and knowledge gaps inherent to the authors' paper, which among others include incorrect neurological claims about brain death and misunderstandings regarding the terminology of consciousness. Although we believe that (near‐)death research deserves a framework guideline, the paper by Parnia and colleagues is misleading and, contrary to the authors' intention, hinders the scientific understanding of near‐death experiences and the neural mechanisms occurring in the dying brain. [ABSTRACT FROM AUTHOR]