Molecular evidence for the lack of epidermal growth factor receptor gene expression in small cell lung carcinoma cells.

It has been shown that none of the small cell lung carcinoma (SCLC) cell lines possess epidermal growth factor (EGF) binding activity on their surface. We have examined several SCLC cell lines for the possibility that they may have EGF receptors but that the receptors are masked by an EGF-like protein factor(s), which may be produced by an autocrine mechanism. No evidence, however, was found for the production of such factors. We then used an EGF receptor complementary DNA to determine the state of the EGF receptor gene by Southern blot analysis. The receptor gene appears to be present in these cells in an intact, unrearranged form. These cells, however, were found to lack detectable levels of EGF receptor mRNA, suggesting a possible reason for the absence of EGF receptors on the cell surface. Furthermore, karyotype analysis revealed that SCLC cell lines Lu134 and H69 contained a morphologically normal chromosome 7, which carries the EGF receptor gene. Also, these SCLC cells contained the apparently normal chromosome 3 and exhibited the presence of c-raf-1 gene in an unrearranged form. Thus, the previously noted partial deletion of chromosome 3 is not necessarily common to the SCLC cells. Instead, the lack of EGF receptor is frequently found in SCLC cell lines and is distinct from the other types of lung cancer. We postulate that SCLC cells have some active regulatory mechanism which prevents the expression of EGF receptor gene.

[Hemodynamics and serum nitroglycerin concentration during intraoperative use of nitroglycerin patches].

We investigated the effect of number of nitroglycerin (TNG) as patches, containing 5 mg of TNG per sheet, on hemodynamics in 29 adult patients undergoing elective surgery. Patients were randomly allocated to four groups according to the number of the sheets applied (0, 2, 5 and 10 sheets). Hemodynamics as well as plasma TNG concentration were measured at 4 points (just before and 30, 60 or 120 minutes after application of TNG patch) in each group (n > or = 6). Plasma TNG concentrations depended on the number of the sheets and increased until 120 min after the application. Mean arterial pressure decreased gradually and significantly after applying two sheets or more. However, no relation was observed between the plasma concentration of TNG and the decrease in mean arterial pressure. We conclude that induced hypotension can not be intensified by increasing the number of the sheets of TNG patch.

Characterization of an intergroup serological mutant from group II RNA phage GA.

Starting from the group II RNA phage GA which has an amber mutation in the maturation protein cistron, a spontaneous mutant of group II phage GA, whose serological and electrophoretic properties became similar to those of group I phage MS2, was isolated and analyzed. The mutant has now become sensitive to anti-MS2 serum and resistant to anti-GA serum. Analysis of the nucleotide sequence of the coat protein gene revealed that G----A transition was the main change. The deduced amino acid sequence showed that five amino acids were substituted in the mutant, and three of the five became identical to MS2, resulting in increased molecular weight of the coat protein. However, it did not complement MS2. These results suggested that the serological change from group II phage GA type to group I phage MS2 type is induced spontaneously at high frequency by minor nucleotide changes in coat protein gene, and confirmed the previous results at the RNA level that MS2 and GA were related although the closeness between them seems somewhat remoter than that of groups III and IV (18, Inokuchi et al, unpublished data for the nucleotide sequence of group IV phage SP).

Biochemical characterization of RNA coliphage MX1.

In order to clarify the taxonomic status of an RNA coliphage, MX1 (a serological intermediate between groups III and IV), we examined (i) read-through protein synthesis in a cell-free protein-synthesizing system, (ii) the peptide map of the coat protein and (iii) the RNA sequence in the 3'-terminal region of MX1 RNA. We found that the characteristics of MX1 were closer to those of group III phages than to those of group IV. For example, the gel elecrophoretic pattern of the protein coded for by MX1 RNA was the same as that of group III phage proteins. Peptide fingerprints of the coat protein of MX1 showed that seven tryptic peptides overlapped with corresponding peptides of Q beta (group III phage), whereas only two peptides overlapped with those of SP (group IV phage). Furthermore, in the base sequence of the first 200 nucleotides from the 3'-end of MX1 RNA, about 70% of the nucleotides were homologous to those of the Q beta RNA, whereas the homology to SP RNA was only 53%. These results suggest that MX1 is more closely related to group III phages than to group IV phages and we propose that it should be assigned to the former group.