Effects of isolation and culture on prostaglandin synthesis by porcine aortic endothelial and smooth muscle cells

Freshly isolated neonatal porcine aortic tissue (smooth muscle with or without endothelium present) produced approximately 30 ng/mg wet tissue of 6-oxo-prostaglandin F1 alpha (the stable hydrolysis product from prostacyclin) and approximately 15 ng/mg of prostaglandin E2, as measured by radioimmunoassay after 24 h incubation in culture medium. Primary cultures of porcine endothelial and smooth muscle cells (isolated by enzymic digestion of aortic tissue) exhibited the same pattern of prostaglandin production, but absolute values were greater than for fresh tissue, particularly in the case of endothelium. Subcultures of endothelium produced smaller amounts of prostaglandins, although the pattern remained similar. In contrast, subcultures of smooth muscle cells produced a greater total amount of prostaglandins than did primary cultures, and the main product was prostaglandin E2. Experiments with [14C] prostaglandin H2 or [14C]arachidonic acid confirmed that aortic tissue, cultured endothelium, and primary cultures or aortic smooth muscle cells synthesized prostacyclin, and demonstrated that subcultured smooth muscle cells enzymically isomerised prostaglandin H2 to prostaglandin E2. Kinetic studies showed that prostaglandin production by cultured vascular cells was transiently increased by subculture or changing the growth medium, and that production per cell declined with increasing cell density. The change in pattern of prostaglandin production during culture was shown to be due to a rapid decline in the rate of prostacyclin production (which apparently began immediately after tissue isolation), together with a more gradual rise in prostaglandin E2 production. These results indicate that the amounts and ratios of prostaglandins produced by vascular endothelial and smooth muscle cells are greatly affected by the conditions used to isolate and culture the cells; vascular cells in vivo may similarly alter their pattern of prostaglandin production in response to local changes in their environment.     

Effect of phenethylbiguanide on sugar and amino acid transport in rabbit ileum

Phenethylbiguanide has been shown to be an inhibitor of sugar and amino acid uptake in both $\text{in vivo}$ and $\text{in vitro}$ conditions. This action could be due to a competition for sodium sites on the sugar and amino acid carrier molecules. The effects of phenethylbiguanide on $\text{in vitro}$ intestinal preparations indicate that this compound has a time-dependent effect, it is most effective when placed on the mucosal surface but is also effective on the serosal surface. Furthermore, competition studies indicate that it is a competitive inhibitor of sugar uptake and a non-competitive inhibitor of amino acid uptake. These results are consistent with the differences in the mechanism of coupled transport between sugars and amino acids, but, do not substantiate the idea that phenethylbiguanide competes for the sodium site on the ternary carrier.     

Combination v. sequential therapy with melphalan, 5-fluorouracil and methotrexate for advanced ovarian cancer.

The results of a national clinical trial to compare combination and sequential chemotherapy for stage III or IV ovarian cancer are reported. Of the 253 patients from 16 centres across Canada who were admitted to the trial 13 were excluded from the analysis. All the patients were observed for 2 to 5 years from entry into the trial. There were no differences in response to therapy or in survival between the patients treated with melphalan followed by 5-fluorouracil and then by methotrexate in high dosage and the patients treated with the same agents in combination. Patients with minimal residual disease after resection of stage III ovarian cancer had a good prognosis. Other favourable prognostic factors were age (less than 55 years), performance status (90% or 100% on the Karnofsky scale) and histologic grade of the tumour.     

Computer programs for analysis of nucleic acid hybridization, thermal denaturation, and gel electrophoresis data.

Computer programs for the analysis of data from techniques frequently used in nucleic acids research are described. In addition to calculating non-linear, least-squares solutions to equations describing these systems, the programs allow for data editing, normalization, plotting and storage, and are flexible and simple to use. Typical applications of the programs are described.     

Chemo-adoptive immunotherapy against a guinea-pig leukemia

Summary Strain-2 guinea-pigs bearing the transplantable L₂C leukemia were treated with cytoxan 24 h prior to receiving an injection of either allogeneic or syngeneic spleen cells from donors preimmunized to the leukemia. Treatment with the drug alone produced a remission period which lasted for 4–5 weeks before eventual relapse and death. An IP transfer of spleen or peritoneal exudate (PE) cells from syngeneic strain-2 guinea-pigs hyperimmunized to the leukemia greatly extended the survival times of drug-treated animals beyond that observed in animals receiving normal strain-2 cells. Long-term survivors were refractory to a subsequent challenge with a lethal inoculum of L₂C cells. A reduced tumor load was essential for an immunotherapeutic effect of adoptively transferred cells. The use of sensitized lymphocytes alone failed to control the established disease. Hyperimmune spleen cells from strain-13 and Hartley guinea-pigs also demonstrated a slight capacity to inhibit the proliferation of leukemia cells when injected into diseased animals previously treated with the drug. Due to inadequate drug suppression, however, the injection of allogeneic cells from either immune strain-13 or Hartley guinea-pigs did not prolong the latent period for the appearance of the leukemia to the same extent as either immune strain-2 spleen or PE cells. A marked delay in the onset of disease was noted when immune spleen cells from either syngeneic or allogeneic sources were mixed in vitro with L₂C leukemia cells at a ratio of 200:1 before injection back into normal strain-2 animals. However, an exposure of L₂C blast cells in vitro with heat-inactivated serum obtained from L₂C-immune strain-2 animals significantly enhanced the onset of disease.     

Human lymphocyte subpopulations: the effect of pregnancy.

Peripheral blood lymphocytes from pregnant and nonpregnant females were studied for the presence of the following surface receptors: (i) Receptor for heat-aggregated human IgG (AggIgG); (ii) Receptor(s) for complement components; (iii) Receptor for sheep red blood cells (SRBC). Absolute numbers of lymphocytes with receptors for complement and those with receptors for SRBC were present in equal numbers in both groups. However, in the pregnant females there was a significantly lower number of lymphocytes with receptors for AggIgG. It is hypothesized that some of the immunological changes which occur during pregnancy may be mediated partly through changes in the total numbers of certain lymphocyte subpopulations.