Altered growth factor requirements and cell cycle control in rat hepatoma cells versus adult rat hepatocytes in culture.

Adult rat hepatocytes multiply in primary cultures when incubated in arginine-free MX-83 medium supplemented with dialyzed fetal calf serum, insulin, glucagon, hydrocortisone, epidermal growth factor, and transferrin. In the absence of mitogens, the fraction of the cells engaged in DNA synthesis dropped sharply. However, cells initiated DNA synthesis in response to the mitogenic mixture indicating that hepatocyte proliferation is controlled by G1----S transition rates.

Nonlinear relationship between pacing and evoked QT intervals.

The paced evoked response is an established biosensor which has been used in the design of a rate responsive pacemaker. The unit is capable of sensing the interval between the delivery of a pacing stimulus and the downslope of the evoked T wave. With fixed rate pacing this interval has been shown to shorten with exercise and the main cause of this effect is thought to be mediated by the increase in the plasma catecholamines which are released on exertion.

Differences between normal and transformed murine fibroblasts in the expression of various promoter/enhancer-chloramphenicol acetyltransferase constructs.

High levels of poly(A)+ RNAs homologous to certain endogenous retrovirus-related DNA sequences are frequently seen in carcinogen-transformed rodent cells. To explore the underlying mechanism, transient expression assays were done to determine whether carcinogen- or radiation-transformed C3H 10T 1/2 cell lines differ from normal 10T 1/2 cells in terms of their ability to express the chloramphenicol acetyltransferase (CAT) gene when it is linked to various promoter/enhancer sequences, including two independently isolated intracisternal A particle (IAP) long terminal repeat sequences designated prcm and pMIA6. We found that with several constructs, CAT activity was always 3- to 10-fold higher in the transformed 10T 1/2 cell lines than in the normal 10T 1/2 cells.

Hydrocortisone-induced accumulation of fibronectin mRNA and cell surface-associated fibronectin.

A Morris hepatoma 7777-derived cell line, DTH-3, was used to study the control of fibronectin gene expression. In cultures of DTH-3 cells in conventional medium supplemented with serum or in chemically defined MX-83 medium supplemented with insulin no cell surface fibronectin was detectable by indirect immunofluorescence techniques using specific polyclonal antibodies. By Northern blot hybridization analysis a dose- and time-dependent accumulation of 8 kb fibronectin mRNA in response to hydrocortisone treatment was demonstrated.

Automatic pacemaker termination of two different types of supraventricular tachycardia.

A new antitachycardia pacemaker system was used in a 58 year old woman to terminate two different types of supraventricular tachycardia by a single automatic pacing mode. During the invasive electrophysiologic study before pacemaker implantation (in the absence of medication), sustained episodes of atrioventricular (AV) nodal reentrant tachycardia and two short-lasting episodes of nonsustained atrial tachycardia were induced. After implantation, sustained episodes of both AV nodal tachycardia and atrial tachycardia were initiated.

Tone-burst modulated color-center-laser spectroscopy.

A new modulation technique useful for high-resolution spectroscopy with tunable infrared lasers is described. The high sensitivity of this method is demonstrated by measurements of NOupsilon = O? 2 overtone transitions and of transitions in the fundamental band of OH with a color-center laser operating near 2.7 microm.

Impaired autologous mixed lymphocyte reactivity in Hodgkin's disease.

In patients with Hodgkin's disease, the impaired immune reactivity, especially of the thymus dependent system, is well established. This decreased immune response of the lymphocytes from the peripheral blood contrast to an increased lymphocytopoiesis in the the lymphatic organs with a hyperplasia of these tissues. We studied the reactivity of peripheral T lymphocytes from 20 patients with Hodgkin's disease and 26 healthy control persons against autologous and allogeneic non T cells respectively in the mixed lymphocyte culture (MLC).

In vitro induction of experimental autoimmune orchitis: characterization of a primary T lymhocyte response against testicular self antigens.

Lymphocytes from normal, young adult rats were autosensitized in vitro against trypsin-dissociated autologous testis cells. The autoimmune response had been assayed both by determination of the lymphocyte proliferation, using a (3H)thymidine incorporation test, as well as by determination of their specific cytostatic activity against monolayer-forming testis cells which was measured in a terminal 51Cr uptake assay. The actively responding cells in this system are T lymphocytes.

Experimental autoimmune orchitis: in vitro induction of an autoimmune disease.

Experimental autoimmune orchitis (EAO) can be induced in vitro. Normal lymph node lymphocytes cultured with autologous dissociated testis cells form rosette-like aggregates and later undergo blast transformation and proliferation. These stimulated lymphocytes cause in vivo EAO lesions, when injectd into syngeneic recipients.