This paper deals with the extant view that neuroendocrine cells, in particular regulatory peptidecontaining neurons and gastro-entero-pancreatic endocrine cells, have a common embryonic origin in ‘neuroendocrine-programmed epiblast’. For a common origin to be of significance, programming of the features shared by these cell types should occur at a single site and at the same time. It is argued that this is most unlikely. Hence the neuroendocrine programme must be imparted to cells in different parts of the embryo, possibly at different times i.e. the same or closely related parts of the genome must be activated in cells in different localities, quite possibly by different mechanisms. The import of the argument presented is that similarities between different cell types are not necessarily the outcome of a common embryonic origin (in any meaningful sense of the phrase). Neuroendocrine cells exemplify this principle.

The organization of an 18 kilobase (kb) nuclear DNA fragment containing the entire human interleukin 2 (IL-2) gene was investigated by Southern blot analysis and DNA sequencing. A 6 kb cluster of the KpnI families is located 3 kb upstream from the 5’ end of the IL-2 gene. The members of the cluster and their arrangements are identical to previous determinations of the KpnI cluster present in the human β-globin gene region. One of the Alu family and a d(A-C)₁₄d(T-C)₂₄ sequence are linked and are located 2.5 kb downstream from the 3’ end of the IL-2 gene. This Alu sequence is flanked with 10 basepair (bp) direct repeats, and the Alu and the homocopolymer sequences seem to form a composite movable element, as deduced from the finding that this unit is also flanked with 6 bp direct repeats. Tissue-specific DNA rearrangements were examined in the 5’ flanking region of the human IL-2 gene.

By sodium dodecyl sulfate (SDS)-gel electrophoresis, several types of connectin, an elastic protein of vertebrate skeletal muscle, different in their electrophoretic mobility, were detected in embryonic, neonatal and adult skeletal muscles of the chicken: embryonic, α, β, β’, neonatal α, and adult α, β, β’. The relative mobility was slower in the following order: embryonic α<neonatal α<adult α<embryonic β<embryonic β’=adult β<adult β’. As revealed by fluorescent immunoblots, embryonic types of connectin were reactive with polyclonal antibodies against adult β-connectin which is the proteolytic product of adult α-connectin. Embryonic and neonatal α-connectins were found from day 7 of incubation to day 3 posthatch, and from the day of hatch to day 7 posthatch, respectively. Adult α-connectin appeared on day 5 after hatch. Embryonic β-connectin was present until day 3 posthatch and adult β’-connectin was detected from day 5 after hatch on. Embryonic β’-and/or adult β-connectins were present from the 7th day of incubation and thereafter. The two types of connectin were not distinguishable by SDS-gel electrophoresis.

The effects of pirenzepine, a selective antimuscarinic agent, on both carbachol-stimulated amylase release and [³H]N-methyl scopolamine ([³H]NMS) binding were studied in isolated mouse pancreatic acini. Pirenzepine at concentrations between 0.1-3.0 μM was found to inhibit carbachol-stimulated amylase release without any appreciable effect on the basal amylase secretion. The inhibition by pirenzepine was rapid and reversible. Biphasic dose-response curves to carbachol for amylase release shifted to the right with an increase in pirenzepine concentration, and pA₂ value was estimated to be 6.8. IC₅₀ of pirenzepine for carbachol-stimulated amylase release was 440 nM, and the potency of pirenzepine on the inhibition of amylase release was 2% relative to atropine. The effect of pirenzepine was selective for carbachol; amylase release stimulated by other secretagogues such as cholecystokinin (CCK), bombesin and Ca²⁺ ionophore A23187, was not affected by pirenzepine. In addition, pirenzepine was found to inhibit the specific binding of [³H]NMS, a muscarinic antagonist, to mouse pancreatic acini. The potency of pirenzepine in this action was 1% relative to atropine. The inhibitory effect of pirenzepine on receptor binding was selective for the muscarinic receptor. These results indicate that pirenzepine is a specific but relatively weak antagonist of muscarinic receptor in mouse pancreatic acini.

1)Antibodies against rabbit skeletal muscle troponin C and I were raised in goats. The effect of the antibodies was examined on the calcium-sensitive ATPase of natural actomyosin (myosin B) and actomyosin containing tropomyosin and various combinations of three troponin components (C-I-T). 2) Both anti-troponin C and anti-troponin I accelerated the ATPase of natural actomyosin and actomyosin in the presence of tropomyosin and three troponin components about 2-fold at high calcium concentration (4.6x10^-5 M). At low calcium concentration (2.4x10^-8 M), both antibodies also potentiated the ATPase 2-to 3-fold. 3) In the presence of incomplete combinations of troponin components (troponin I, troponin I-T or troponin C-I), anti-troponin I did not affect the ATPase of actomyosin at all calcium concentrations. 4) In the presence of troponin C-I, anti-troponin C accelerated the actomyosin ATPase definitely at high calcium concentration, but inhibited it at low calcium concentration to some extent. 5) Both anti-troponin I and anti-troponin C coprecipitated with natural actomyosin (actomyosintropomyosin-troponin C-I-T) regardless of calcium concentrations. On the other hand, actomyosin containing tropomyosin-troponin I-C was found to coprecipitate with anti-troponin C, but not with anti-toponin I. 6) When troponin T was replaced by its chymotryptic subfragment, i.e. troponin T₂, the actomyosin ATPase was not affected by anti-troponin I, but was potentiated by anti-troponin C at all calcium concentrations.

The effect of sera from nine patients with fulminant hepatic failure on liver cell growth was investigated by use of adult rat liver cells in primary culture. All nine sera stimulated DNA synthesis in hepatocytes more effectively than normal human serum, which had only slight growth-promoting activity. Moreover four of the sera showed marked stimulatory activity on DNA synthesis of more than 10 times that of normal human serum. The serum with the highest activity had a dose-dependent effect, and its effect at 10% concentration was greater than that of a combination of the optimal concentrations of insulin and epidermal growth factor. Autoradiographic and morphological data showed that cells that replicated and increased in number in the presence of this serum were parenchymal hepatocytes.

The effects of dorsal root stimulation on the release of endogenous glutamate and aspartate from the hemisected or intra-arterially perfused frog spinal cord were studied. The release of amino acids was measured using a gas chromatograph-mass spectrometer. Repetitive stimulation applied to the dorsal roots produced ventral root potentials and caused a significant increase in the glutamate releases above the resting efflux. In low Ca solution, the ventral root potential was abolished and the glutamate efflux following dorsal root stimulation was significantly decreased. In these experiments, the stimulus strength was adjusted just maximal for the fast ventral root potential. The resting efflux and the evoked release of aspartate caused by dorsal root stimulation was much smaller than the glutamate release. It is suggested that glutamate is an excitatory transmitter in primary afferents that mediates the fast synaptic transmission in the frog spinal cord.

The release of glutamate and aspartate from the hemisected frog spinal cord was measured using black widow spider venom (BWSV), substance P (SP) and bradykinin (BK). The concentration of glutamate and aspartate in the perfusate was measured by fragmentography. The release of glutamate and aspartate was increased by treatment with BWSV. Application of 100 μM SP and BK increased the release of glutamate with little change in the aspartate release. The release of glutamate produced by BWSV and peptides was observed in the presence of tetrodotoxin (10^-7 g/ml). It is suggested that BWSV and peptides act on the presynaptic terminals and cause the release of transmitter.

An in situ cDNA-mRNA hybridization histochemistry using a proopiomelanocortin(POMC) cDNA was performed in the rat antropyloric and duodenal mucosa to examine whether adrenocorticotropic hormone (ATCH)-related peptides in the gut are really derived from the expression of POMC gene. ACTH-related peptides were detected immunohistochemically using antiserum against ACTH. Cells with POMC-specific mRNA and ACTH-related peptides were found to scatter in the basal portion of antropyloric and duodenal mucosa, suggesting strongly that POMC is synthesized in some epithelial cells in the gut. Furthermore, it was also observed that some of inflammatory cells such as lymphocytes in the tunica propria were reactive to both POMC cDNA and ACTH-antiserum.

During the immunohistochemical investigations of catecholamine neurons in human fetal brain stems using tyrosine hydroxylase (TH) as a marker, the subnucleus gelatinosus of the nucleus tractus solitarii was found to contain many small TH-immunoreactive neurons, 10-15 μm in diameter. The finding indicates that this particular subdivision of the nucleus tractus solitarii is a catecholaminergic nucleus. Ultrastructural features of the subnucleus were also described.