High levels of NGF have recently been detected in cerebral cortex and hippocampus, and it was suggested that NGF supports cholinergic, basal forebrain neurons. The present study directly examined whether NGF levels are altered in the neonatal hippocampus following cholinergic denervation by transection of the fimbria. Ten days after transection, hippocampal cholinergic innervation, as assessed by AChE histochemistry and CAT immunohistochemistry, was decreased, and both hippocampal NGF mRNA and protein were elevated about 50%. This indicates possible lesion-induced transcriptional control of neonatal hippocampal NGF levels. This increase was specific to lesions of cholinergic systems, as entorhinal cortex ablation, which removes other afferent fibers to the hippocampus, did not cause a similar increase. At 30 d after fimbria transection, hippocampal NGF mRNA and protein did not differ from control levels, but the decrease in AChE and CAT staining persisted. Peripheral sympathectomy carried out in the adult rat resulted in 2- to 5-fold increases in NGF protein levels in heart atrium and ventricle, as well as submandibular gland, with no concomitant increase in NGF mRNA. Therefore, the control of NGF levels in the adult PNS is probably posttranscriptional. Our results strongly suggest that NGF is involved in the regulation of central cholinergic neurons and is transiently elevated in the neonatal hippocampus following cholinergic lesion.

Acetylcholine↗

PubMed1986

C-myc expression is dissociated from DNA synthesis and cell division in Xenopus oocyte and early embryonic development.

The combined use of a human c-myc probe and of an antibody raised against the human c-myc gene product demonstrated that the Xenopus cells contained a 2.5-kb c-myc transcript and synthesized a c-myc immunoreactive 65-kd polypeptide. In full-grown oocytes, p65c-myc was predominantly located in the nucleus. In non-dividing Xenopus oocytes c-myc mRNA was present at a steady-state level 10(4) times higher than that of growing somatic A6 cells. This very high level of c-myc transcript was reached early in oogenesis and remained constant thereafter. The rate of p65c-myc synthesis also reached high levels, but only in vitellogenic oocytes, suggesting a post-transcriptional control. Although the cell cycle is resumed at a very fast pace in developing embryos, no further increase in total embryonic content of c-myc RNA could be demonstrated up to the swimming tadpole stage. Furthermore, in embryos the rate of synthesis of p65c-myc decreased to a level markedly lower than that of cell cycle-arrested vitellogenic oocytes. This observation suggests that the function of the c-myc gene in the cell cycle may not be implicated directly in sustaining DNA synthesis or mitosis.

Animals↗

PubMed1986

Beta 2-adrenoceptor selectivity in four series of beta-adrenoceptor agonists.

We studied the effect of two catechol and two resorcinol series of beta-adrenoceptor agonists on isolated papillary (beta 1-adrenoceptors) and soleus (beta 2-adrenoceptors) muscles preparations from the guinea-pig. One of the catechol and one of the resorcinol series were substituted by branched alkyl groups on the amino nitrogen, and the other two series were substituted by cycloalkyl groups. It was found that: the catechol derivatives were more potent than their corresponding resorcinol derivatives on both the papillary and the soleus muscle preparations, the resorcinol derivatives were more selective for the soleus muscle than their corresponding catechol derivatives, the substitution on the amino nitrogen gave compounds that were highly selective for the soleus muscle, both in the catechol and the resorcinol series. Greatest selectivity was obtained with a tertiary butyl group. the branched alkyl substitution on the amino nitrogen favoured selectivity for the soleus muscle more than cycloalkyl substitution did.

Adrenergic beta-Agonists↗

PubMed1986

Structure and expression of the chicken beta nerve growth factor gene.

The 3' exon of the chicken beta nerve growth factor (NGF) gene was isolated by the use of a murine cDNA probe. DNA sequence analysis of the clone suggests a mature chicken NGF protein of 118 amino acids, showing approximately 85% homology to mouse and human NGF. In addition to this conservation of the mature NGF, parts of the propeptide and the untranslated 3' end of the NGF gene are also highly homologous in chicken, human and mouse. Therefore, these sequences probably subserve important functions. Expression of NGF mRNA in various chicken tissues was examined by RNA blot analysis with a chicken NGF probe. A single mRNA of 1.3 kb was detected at high levels in heart and brain of 10-week-old roosters, and, at lower levels in spleen, liver and skeletal muscle. These data suggest a correlation between NGF expression and the density of sympathetic innervation in peripheral organs, in analogy with findings for mammalian tissues. In the adult avian brain, NGF mRNA is found at higher concentration in the optic tectum and cerebellum than in the cortex and hippocampus. This pattern of NGF expression differs from that previously described for the rat brain. During late stages of development (day 18), NGF mRNA was expressed both in heart and brain of embryos but at lower levels than in the adult.

Amino Acid Sequence↗

PubMed1986

Development and regional expression of beta nerve growth factor messenger RNA and protein in the rat central nervous system.

The presence of nerve growth factor (NGF) mRNA and protein in the rat central nervous system is documented. Blot-hybridization analysis showed an abundance of NGF mRNA in the hippocampus, cerebral cortex, and olfactory bulb. Enzyme immunoassay confirmed significant levels of a NGF-like protein in the hippocampus and cerebral cortex. Bioassay of a NGF-like immunoaffinity-purified protein from these regions was physiologically indistinguishable from NGF. Immunohistochemistry revealed a widespread distribution of NGF-like reactivity in the adult brain, preferentially in fiber tracts. NGF mRNA accumulation began at birth, with adult levels reached 3 weeks postnatally. Enzyme immunoassay detected the presence of a NGF-like protein in the embryonic rat brain. Postnatally, the level of NGF-like protein reached a maximum at 3 weeks. Additionally, a distinct fetal form of NGF may exist.

Animals↗

PubMed1986

Iron losses in sweat.

The losses of iron in whole body cell-free sweat were determined in eleven healthy men. A new experimental design was used with a very careful cleaning procedure of the skin and repeated consecutive sampling periods of sweat in a sauna. The purpose was to achieve a steady state of sweat iron losses with minimal influence from iron originating from desquamated cells and iron contaminating the skin. A steady state was reached in the third sauna period (second sweat sampling period). Iron loss was directly related to the volume of sweat lost and amounted to 22.5 micrograms iron/l sweat. The findings indicate that iron is a physiological constituent of sweat and derived not only from contamination. Present results imply that variations in the amount of sweat lost will have only a marginal effect on the variation in total body iron losses.

Adult↗

PubMed1986

Multiple growth-associated nuclear proteins immunoprecipitated by antisera raised against human c-myc peptide antigens.

Different antisera raised against various regions of the human c-myc protein were used to identify four human c-myc proteins with apparent molecular masses in sodium dodecyl sulfate-polyacrylamide gels ranging from 64 to 68 kilodaltons (phosphoproteins pp64 and pp67 and nonphosphorylated proteins p65 and p68). pp64 and p65 were the major detectable c-myc proteins, and pp67 and p68 were minor but specific components of the immunoprecipitates. The c-myc proteins were all localized in the cell nucleus. Accumulation of [35S]methionine-labeled p65 was observed after pulse-labeling and chase, suggesting that the stable p65 c-myc protein is generated posttranslationally from short-lived precursors. pp64, pp67, and p68 possessed short half-lives and may therefore be precursors of the stable p65. Confirmation of the nuclear localization of the human c-myc proteins was obtained by immunofluorescent staining. The human c-myc proteins were revealed as a pattern of punctate nuclear staining with, particularly for p65, nucleolar enhancement that left an unstained annulus surrounding the nucleolus.

Antigens, Neoplasm↗

PubMed1985

Coexpression of the sis and myc proto-oncogenes in developing human placenta suggests autocrine control of trophoblast growth.

First trimester human placentas actively express the sis proto-oncogene, the structural gene for the B chain of platelet-derived growth factor (PDGF). Using the in situ hybridization technique, the 4.2 kb c-sis transcript has been localized to the cytotrophoblastic component, especially the highly proliferative and invasive cytotrophoblastic shell, paralleling the distribution of c-myc transcripts in early placenta. Explants of first trimester placenta release significant levels of PDGF-like activity into the medium under apparent developmental control. Moreover, cultured trophoblasts display abundant high-affinity PDGF receptors and respond to exogenous authentic PDGF by an activation of the c-myc gene and DNA synthesis. The developing human placenta may therefore represent a case of autocrine growth regulation in a normal tissue, in which cells bearing receptors for a growth factor can also synthesize and respond to that factor.

Cell Line↗

PubMed1985

Mycoplasma mimicry of lymphokine activity in T-cell lines.

During screening of T-T hybridomas for B-cell-stimulating factors (BSF) we found in the conditioned medium of such a line (TUH-14) an activity that turned out to cosediment with a contaminating strain of Mycoplasma arginini on centrifugation. Since it only affected B blasts and only to a minor extent small cells and since it did not induce immunoglobulin secretion, the mycoplasma strain seemed to mimic a BSF. M. arginini was also found in two other T-T hybridoma producer lines but not in a clone of the EL-4 line. Three other M. arginini isolates were not stimulatory for B cells. The presented results point towards the importance of careful control for mycoplasma contamination in established cell lines.

Animals↗

PubMed1985

Growth-dependent synthesis of c-myc-encoded proteins: early stimulation by serum factors in synchronized mouse 3T3 cells.

Synthesis of the c-myc gene product was measured during the entire cell cycle of subconfluent mouse 3T3 cells with an antibody raised against a human c-myc synthetic peptide. The antiserum recognized two mouse c-myc-encoded proteins with apparent molecular weights in sodium dodecyl sulfate-polyacrylamide gels of 62,000 and 60,000. Cell-derived p62 was compared with the mouse c-myc gene product synthesized in vitro. Immunoprecipitation, electrophoretic analyses, and peptide mapping provided evidence that p62 is encoded by the mouse c-myc gene. The rate of synthesis of the c-myc proteins was tightly coupled to the cellular growth state of nontransformed A31 3T3 cells, but not to that of their benzo(a)pyrene-transformed derivative (BPA31). Furthermore, the synthesis of the c-myc proteins was stimulated by the exposure of confluent, density-arrested A31 cells to platelet-derived growth factor or fibroblast growth factor. Tightly synchronized cell populations were obtained on the addition of serum factors to subconfluent, serum-deprived A31 cells, and c-myc expression could be monitored for more than one complete cell cycle. One hour after stimulation the steady-state level of the 2.2 kilobase c-myc transcript increased 30-fold relative to that of quiescent cells and decreased thereafter to the level observed during exponential growth. The rate of synthesis of c-myc-encoded proteins was determined by immunoprecipitation after a 2-h labeling period. After an initial sevenfold increase detectable 2 h after serum addition, the rate of synthesis remained constant throughout the rest of the cell cycle. No further changes associated with the late prereplicative period, S phase, G2, or mitosis could be demonstrated. Pulse-chase and long-term labeling experiments revealed different half-lives for the two c-myc-encoded proteins. The half-lives of the c-myc proteins, however, were independent of the cellular growth state. The sustained expression observed throughout the cell cycle suggests that the growth-related function of c-myc may be required during the G0-G1 transition and in all phases of the cycle of the growing cell.

Animals↗

PubMed1985

Unusual neurological symptoms in a case of severe crotalid envenomation.

In Sweden bites by non-European venomous snakes are reported to the Poison Information Centre 5-10 times annually. These incidents generally take place in private homes and may result in severe poisoning. We report a recent case of envenomation from a bite by Crotalus durissus terrificus with a prolonged, atypical course. The patient, a 24-year old man, was admitted to hospital approximately eight hours after the snakebite. On admission we noted coma, circulatory failure, hypofibrinogenaemia with bleeding from fang marks on his right arm, melaena and haematemesis. Antishock therapy including intravenous fluids, steroids and epinephrine was instituted immediately and within six hours infusion of polyvalent antivenom was started. Next day, when the initial disturbances were corrected, peripheral neurological features were noted and the patient gradually became comatose. Antivenin therapy was reinstituted. The coma lasted for one week and recovery extended over several months with persisting neurological symptoms. Six months after the bite there were still pathological findings in the electromyogram.

Adult↗