Transcriptional regulation of early growth response genes in FOS-expressing PC-12 cells

Deregulated c-fos expression in the rat pheochromocytoma cell line, PC-12, causes pronounced downregulation of nerve growth factor (NGF)-induced c-fos and c-jun activation, accompanied by a block in NGF-induced differentiation of PC-12 cells. The FOS-expressing PC-12 cells were exposed to diverse agents such as NGF, epidermal growth factor (EGF), basic fibroblast growth factor (bFGF), interleukin-1 beta (IL-1 beta), interleukin-6 (IL-6), dibutyryl cyclic adenosine 3',5' monophosphate (db cAMP), and Ca-ionophore; and the expression of egr-1, c-fos, c-jun, jun-B, and jun-D was analyzed. Pronounced downregulation of c-fos, c-jun, and--to a lesser extent--jun-B was observed on treatment with NGF, bFGF, db cAMP, and Ca-ionophore, whereas EGF-induced activation of these early response genes was not inhibited in FOS-expressing PC-12 cells. Ca-ionophore- and db cAMP-induced egr-1 activation in PC-12 fos cells was completely inhibited. Both parent and PC-12 fos cells expressed similar high basal levels of jun-D, whose expression was the least regulatable by all of these agents. Transfection of fos promoter-chloramphenicol acetyltransferase (promoter-CAT) plasmid into these stable FOS-expressing PC-12 cells revealed that these effects are exerted at the fos promoter level.

Erythrocyte and plasma cholinesterase activity in normal pregnancy

Erythrocyte acetylcholinesterase and plasma cholinesterase was estimated in 50 normal pregnant women and 22 age matched normal non-pregnant women. Plasma cholinesterase was significantly decreased while erythrocyte cholinesterase was significantly increased during pregnancy. These changes may be related to altered haemodynamics and or other inter-related changes occurring in pregnancy.

Nerve growth factor-induced differentiation in PC-12 cells is blocked by fos oncogene

Rat pheochromocytoma (PC-12) cells respond to nerve growth factor (NGF) by cessation of cell division and by expression of several properties resembling those of differentiated sympathetic neurons. Within minutes after addition, NGF rapidly stimulates transient expression of c-fos. To investigate the possible role of c-fos in NGF-induced differentiation, activated mouse c-fos genes were introduced into PC-12 cells by electroporation. Constitutive expression of fos inhibited NGF-induced differentiation although transfected cells harbored intact NGF receptors. Dibutyryl cyclic AMP (db cAMP) and basic fibroblast growth factor (b-FGF)-induced differentiation were also inhibited. Transcriptional activation of c-fos, c-jun, and ornithine decarboxylase (ODC) by NGF was down-regulated, whereas expression of egr-1 was unaffected in PC-12 fos clones. These results suggest that deregulated expression of fos can interfere with the normal role of NGF in neuronal differentiation.

A sensitive technique to monitor gene transfer and expression in bone marrow stem cells

The polymerase chain reaction technique (PCR), a primer-mediated enzymatic amplification of specific target sequences, was used to monitor gene transfer into hematopoietic progenitor stem cells. A gene coding for human interleukin 1 alpha (IL-1 alpha) was cotransfected with the rous sarcoma virus (RSV) CAT plasmid into mouse bone marrow cells by electroporation. Individual chloramphenicol (CAM)-resistant bone marrow progenitor colonies (granulocyte-macrophage colony-forming units; CFU-GM) containing 50-100 cells were analyzed by PCR for the presence and expression of IL-1 alpha and CAT sequences. Amplified IL-1 alpha DNA sequences were detected from a 50-cell CFU-GM colony. CAT and IL-1 alpha RNA expression was demonstrated from the CAM-resistant CFU-GM colonies.

Placental transfer of paracetamol

Paracetamol (1 g orally) was given to each of 10 healthy pregnant women undergoing normal vaginal delivery at the onset of second stage of labour. Following delivery, there was no significant difference in the serum concentration of paracetamol in the mother and the foetus (p less than 0.1), the mean value being 5.925 +/- 2.15 mg/ml and 7.875 +/- 2.22 mg/ml respectively. Paracetamol may be recommended as a safe analgesic-antipyretic during pregnancy and labour.

Idiopathic sclerosing encapsulating peritonitis

Sclerosing encapsulating peritonitis (SEP) was diagnosed in two men, one middle-aged woman, and a prepubertal girl, none of whom had been treated with beta-blockers, peritoneal dialysis, or peritoneal shunting. Idiopathic SEP has hitherto been reported mainly in adolescent females. It is hypothesised that in these patients, who were from two adjacent districts of Rajasthan, an aetiological factor was consumption of cereals infected with fungus that contained biologically active amines.

Transcriptional activation of the c-myc proto-oncogene in murine keratinocytes enhances the response to epidermal growth factor

To investigate the relationship between activation of the c-myc proto-oncogene and the controls of cellular growth and differentiation of epidermal cells, a transcriptionally activated c-myc gene (DM-myc) was introduced into the established murine keratinocytes, BALB/MK. Exponential growth rates of myc-transfectants were not significantly different from that of parental BALB/MK cells. C-myc RNA transcripts were not detectable in confluent, mitogen-deprived cultures of parental BALB/MK cells, whereas four out of five clones expressed elevated levels of myc mRNA under these conditions. All of the cell lines, however, displayed density-dependent growth arrest in the G0/1 phase of the cell cycle. Maximal stimulation of quiescent BALB/MK cells with epidermal growth factor (EGF) caused a 70- to 100-fold increase of [methyl-3H]-thymidine incorporation into DNA. In the four subclones that expressed the myc gene, the peak thymidine incorporation into DNA was significantly higher than in BALB/MK cells, ranging from 340- to 650-fold control levels. This increased sensitivity to EGF was not due to autocrine mitogenic activity or to a change of EGF binding. Type beta transforming growth factor strongly inhibited the EGF-induced DNA synthesis in BALB/MK cultures as well as in each of the five transfectants (IC50 4-40 pM). Furthermore, both BALB/MK cells and the transfected subclones could be induced to form cornified cell envelopes by increasing the extracellular concentration of calcium. Thus, the constitutive expression of c-myc in BALB/MK appears to affect predominantly the reinitiation of DNA synthesis by EGF.

Dayglow photometry: a new approach

A unique photometer capable of measuring line intensities of <0.1% of the bright background continuum (5 x 10(6)/A) has been developed and successfully commissioned for the measurement of daytime OI 630.0-nm emission from the thermosphere. The photometer employs a low resolution (10(4)) Fabry-Perot etalon, temperature tuned narrowband (3-A) interference filter, radial chopper, and up/down counting system. The optimum choice of the photometer parameters and a unique method of eliminating the background enabled us to overcome the limitations of the earlier attempts to make measurements on such phenomena as dayglow and has opened up a wide range of uses. However, at present, it is being discussed only in the context of dayglow measurements.

A method to detect transfected chloramphenicol acetyltransferase gene expression in intact animals

A rapid procedure is described for assaying chloramphenicol acetyltransferase (CAT, EC 2.3.1.28) enzyme activity in intact animals following transfection of the RSV CAT plasmid into mouse bone marrow cells by electroporation. The reconstituted mice were injected with [14C]chloramphenicol and ethyl acetate extracts of 24-h urine samples were analyzed by TLC autoradiography for the excretion of 14C-labeled metabolites. CAT expression in vivo can be detected by the presence of acetylated 14C-labeled metabolites in the urine within 1 week after bone marrow transplantation and, under the conditions described, these metabolites can be detected for at least 3 months. CAT expression in intact mice as monitored by the urine assay correlates with the CAT expression in the hematopoietic tissues assayed in vitro. This method offers a quick mode of screening for introduced CAT gene expression in vivo without sacrificing the mice.

Ureteric re-implantation in the neuropathic bladder

During the last 5 years 174 children with neuropathic bladder were studied, and only 7 required urinary diversions. A total of 31 ureteroneocystostomies were performed in 17 patients, 16 of whom had gross vesico-ureteric reflux. Revisionary surgery was required in four children and two underwent pyeloplasty. Deterioration followed ureteroneocystostomy in two patients, but 13 (76 per cent) of the children were significantly improved.

Use of electroporation for high-molecular-weight DNA-mediated gene transfer

Electroporation was used to introduce high-molecular-weight DNA into murine hematopoietic cells and NIH3T3 cells. CCRF-CEM cells were stably transfected with SV2NEO plasmid and the genomic DNA from G-418-resistant clones (greater than 65 kb) was introduced into mouse bone marrow and NIH3T3 cells by electroporation. NEO sequences and expression were detected in the hematopoietic tissues of lethally irradiated mice, with 24% of individual spleen colonies expressing NEO. The frequency of genomic DNA transfer into NIH3T3 cells was 0.25 X 10(-3). Electroporation thus offers a powerful mode of gene transfer not only of cloned genes but also of high-molecular-weight DNA into cells.

Use of electroporation to study the cytotoxic effects of fluorodeoxyuridylate in intact cells

The introduction of 2'-deoxyuridine 5'-monophosphate and its analog, 5-fluoro-2'-deoxyuridine 5'-monophosphate, into intact CCRF-CEM and NIH3T3 cells was achieved by electroporation. Following electroporation, cells were shown to be fully functional as monitored by the incorporation of deoxyuridylate, after conversion to thymidylate, into DNA. Pretreatment of cells with fluorodeoxyuridine completely abolished this effect. In contrast, introduction of the fluoro analog into cells by electroporation markedly inhibited both DNA synthesis and cell growth in a time-dependent manner. Thus, electroporation offers a powerful tool to permeabilize cells to a variety of cellular metabolites and antimetabolites.