Explant organ culture: A review

Organ explant culture models offer several significant advantages for studies of patho-physiologic mechanisms like cell injury, secretion, differentiation and structure development. Organs or small explants/slices can be removed in vivo and maintained in vitro for extended periods of time if careful attention is paid to the media composition, substrate selection, and atmosphere. In the case of human tissues obtained from autopsy or surgery, additional attention must be paid to the postmortem interval, temperature, hydration, and cause of death. Explant organ culture has been effectively utilized to establish outgrowth cell cultures and characterize the histiotypic relationships between the various cell types within an organ or tissue.J. Resau is a visiting scientist at the NCI-LMO-DCE in Frederick, MD 21702, U.S.A.K. Sakamoto is a visiting scientist from the Department of Surgery, Gunma University School of Medicine, Maebashi, Japan     

Macrophage activation for tumor cytotoxicity: Control of cytotoxic activity by the time interval effector and target cells are exposed to lymphokines

Macrophages continuously exposed to lymphokines (LK) and target cells throughout a 48-hr cytotoxicity assay exhibit 3-fold more tumoricidal activity than do cells optimally treated with LK before addition of tumor cells. Increased cytotoxic activity induced by continuous LK treatment was not due to direct toxic effects of LK on tumor target cells or to alterations in target cell susceptibility to cytopathic effects of LK-activated macrophages. Moreover, sensitivities of responsive macrophages to LK activation signals and time courses for onset and loss of tumoricidal activity during continuous exposure or LK pulse were identical. Analysis of macrophage or LK dose responses and time courses for development of cytotoxicity each suggest that differences in tumoricidal activity between macrophages continuously exposed or pulsed with LK were quantitative: the number of cytotoxic events was increased 2.7 ± 0.2-fold (mean ± SEM for 11 experiments) during continuous LK treatment. Optimal levels of macrophage tumoricidal activity then occur only if effector cells, target cells and activation stimuli are simultaneously present for a defined time interval: tumor cells need not be present during the initial 2 to 3 hr of culture; LK can be removed after 8 hr with little or no loss of cytotoxic activity. However, removal of LK or target cells during the critical 4- to 8-hr interval decreased levels of cytotoxicity 3-fold. Thus, nonspecific effector function by LK-activated macrophages in controlled by both the physicochemical nature of the LK mediator and the time interval effector and target cells are exposed to LK.     

Visualization of the 10-nm filament vimentin rings in vascular endothelial cells in situ : Close resemblance to vimentin cytoskeletons found in monolayers in vitro

Surface staining of the intact vascular endothelial cell layer lining the lumen of guinea pig thoracic aorta with antibodies to vimentin revealed that at least 70% of the cells contained intact perinuclear rings of 10-nm filaments. This correlated with the observations made on these cells in culture: 60–80% of the endothelial cells at confluence have complete perinuclear rings. By one- and two-dimensional gel electrophoresis and immunoprecipitation we confirmed that vimentin [17, 18] is the major constituent polypeptide of the 10-nm filaments in guinea pig endothelial cells. These results indicate that the vimentin [17] 10-nm filament cytoskeleton found in guinea pig endothelial cells in vitro is similar to the cytoskeleton found in situ.     

Macrophage activation for tumor cytotoxicity: genetic variation in macrophage tumoricidal capacity among mouse strains.

Development of activated tumoricidal macrophages following Mycobacterium bovis, strain BCG infection in vivo or lymphokine treatment in vitro was examined with more than 20 mouse strains. Peritoneal macrophages from 8 of 22 strains failed to develop tumoricidal capacity by 7 days after intraperitoneal BCG infection. Macrophages from 6 of 6 in vivo nonresponder strains also failed to develop tumoricidal capacity after in vitro treatment with lymphokines. Identification of nonresponder mouse strains should provide a useful resource for analysis of intermediary reactions in macrophage activation.     

Macrophage function in tumor-bearing mice: dissociation of phagocytic and chemotactic responsiveness

Infusion of CBA mice with lymphoid cells from the H-2 compatible but Mls-antigen incompatible C3H × CBA hybrid results in a specifically reduced capacity of the recipients lymphocytes to react in the MLC against C3H-cells. Although this reduction is immunologically specific the results of this investigation have shown that such mice exhibit a strongly reduced capacity to produce humoral antibodies against heterologous erythrocytes and a T-cell independent antigen (PVP).     

Cognitive effects of olanzapine treatment in schizophrenia

Improvement in some but not all domains of cognition during treatment with the atypical antipsychotic drugs clozapine, quetiapine, olanzapine, and risperidone has been reported in some but not all studies. It has been recently suggested that these reports are an artifact, related to lessening of the impairment due to typical neuroleptic drugs and anticholinergic agents. The purpose of this study was to further test the hypothesis that olanzapine, an atypical antipsychotic drug reported to have anticholinergic properties, improves cognition in patients with schizophrenia, including domains of cognition related closely to work and social function (ie, verbal learning and memory) and that this improvement is independent of improvement in psychopathology. Thirty-four patients with schizophrenia who were partial responders to typical antipsychotic drug treatment were evaluated with a comprehensive neurocognitive battery, including measures of executive functioning; verbal and visual learning and memory; working memory; immediate, selective, and sustained attention; perceptual/motor processing; and motor skills prior to and following treatment with olanzapine for 6 weeks. The Brief Psychiatric Rating Scale (BPRS) was used to assess psychopathology in patients treated with typical antipsychotic drugs. Subjects were switched to olanzapine (average dose 13.4 mg, range 5-20 mg) and reassessed following 6 weeks and 6 months of treatment. Significant improvement was noted in 9 of 19 cognitive tests, including measures of selective attention, verbal learning and memory, and verbal fluency. No cognitive test was worsened by olanzapine treatment. Improvements in the BPRS Total and Positive Symptom Subscale scores were noted. Improvements in verbal learning and memory, sustained attention, and psychomotor tracking were independent of improvement in psychopathology. These data suggest that olanzapine improved some but not all cognitive deficits in schizophrenia, including verbal memory, a cognitive domain impaired by anticholinergic drugs. The basis for the improvement in cognitive scores, which should lead to improvement in role functioning if real, is discussed.