Gastrin-releasing peptide-related peptides in a human malignant lung carcinoid tumor

Recent immunohistochemical findings have indicated the presence of gastrin-releasing peptide in normal and pathological human lungs. Gastrin-releasing peptide is a 27-amino acid peptide isolated from porcine gut which bears considerable carboxyterminal homology with bombesin. We have characterized the gastrin-releasing peptide-like peptides present in a human malignant lung carcinoid tumor by gel chromatography and reverse-phase high-performance liquid chromatography. Our results show that this tumor did not contain bombesin; however, this tumor expressed a gastrin-releasing peptide-like compound, several amino-terminal fragments, and a carboxy-terminal fragment of gastrin-releasing peptide.

Identification of pro-opiomelanocortin-derived peptides in the human adrenal medulla

Extracts from adult human adrenals contained high concentrations of immunoreactive beta-endorphin and alpha-melanotropin. Lower quantities of immunoreactive adrenocorticotropic hormone could also be detected. Distribution studies showed the presence of pro-opiomelanocortin fragments in the adrenal medulla. No alpha-melanotropin, beta-endorphin, or adrenocorticotropic hormone could be found in adrenal extracts from several other mammalian species. Analysis of the beta-endorphin-like immunoreactivity using region specific radioimmunoassays interfacing with gel filtration and reverse-phase high-performance liquid chromatography showed the majority of the beta-endorphin-like material to exist as nonacetylated beta-endorphin-(1-31) with a small percentage of lipotropin-sized molecules. The alpha-melanotropin-like immunoreactivity cochromatographed on gel filtration and reverse-phase high-performance liquid chromatography with desacetyl alpha-melanotropin. The data suggest that pro-opiomelanocortin is expressed in the adrenal medulla of humans but is not detectable in the adrenal glands of many other mammalian species.

Measurement of total opioid peptides in rat brain and pituitary by radioimmunoassay directed at the alpha-N-acetyl derivative

A sensitive assay, which cross-reacts with and is specific for diverse opioid peptides, is described. This is based on the prior acetylation of samples and subsequent radioimmunoassay with an antiserum highly specific for the acetylated NH2 terminus of opioid peptides. The result is a procedure that can be used to investigate multiple forms of opioid peptides in extracts of biological material. The sensitivity of the assay is approximately 15 fmol of beta-endorphin per incubation tube, i.e., approximately 100-fold greater sensitivity than the radioreceptor assay used in our laboratory. The peptide concentration required for 50% displacement of trace ranged from 0.65 nM (beta-endorphin) to 1.6 nM (Met-enkephalin). The assay apparently shows an absolute requirement for a free (or acetylated) NH2 terminus corresponding to either a Leu- or Met-enkephalin sequence. Use of the assay with and without prior acetylation of sample provides a method for estimation of the ratio of acetylated:nonacetylated opioid peptides in crude or fractionated extracts. The procedure is used to investigate the forms of opioid peptide found in rat brain and pituitary.

Identification of gastrin releasing peptide-related substances in guinea pig and rat brain

Rat and guinea pig brain extracts were examined for the occurrence of gastrin-releasing peptide (GRP)-like substances by sequence specific radioimmunoassays interfaced with gel filtration and reversed phase high performance liquid chromatography (RP-HPLC). Tryptic digestion of the immunoreactive peptides followed by RP-HPLC was used to further characterize GRP-related peptides in brain. Using these analytical techniques it was found that guinea pig brain extracts contained a peptide with characteristics identical to authentic GRP (27 amino acid residues long). A carboxyterminal fragment with the characteristics of GRP(18-27) as well as a respective aminoterminal fragment with the characteristics of GRP(1-16) were also present in guinea pig brain extracts. The GRP(18-27) seems to correspond to the bombes in related material that has been described previously in mammalian brain extracts. Rat brain extracts also contained a peptide with the characteristics of GRP(18-27). The corresponding aminoterminal fragment, however, behaved differently on RP-HPLC from authentic GRP(1-16) and it was not recognized by antibodies directed to the aminoterminal tridecapeptide fragment of authentic GRP. Similarly the GRP-like peptide from rat brain did not comigrate on RP-HPLC with authentic GRP and was unreactive to antibodies directed toward the aminoterminus of GRP.

Blood pressure elevation in rats by peripheral administration of Tyr-Gly-Gly-Phe-Met-Arg-Phe and the invertebrate neuropeptide, Phe-Met-Arg-Phe-NH2

Phe-Met-Arg-Phe-NH2 (FMRFamide), injected at less than 1 mumol/kg intravenously in the anesthetized rat, produces sharp elevations of blood pressure and changes in respiration. The effects were dependent on the carboxyterminal Arg-Phe (RF) configuration and were stereospecific for these two amino acids. A related peptide with RF carboxyterminus, gamma 1-melanotropic stimulating hormone, also had potent blood pressure stimulating activity. The mechanisms underlying the pressor effect of FMRFamide have not yet been established but this pressor action was not significantly attenuated by standard pharmacologic antagonists or prevented by removal of the adrenal or pituitary gland.

Immunohistochemical localization of dynorphin (1-8) in hypothalamic magnocellular neurons: evidence for absence of proenkephalin

Dynorphin(1-8) immunoreactivity was visualized by immunohistofluorescence in hypothalamic magnocellular neurons of the rat. No immunoreactive met-enkephalin-Arg6-Gly7-Leu8, a fragment of the adrenal medulla pro-enkephalin molecule, was detected in magnocellular neurons. However, a strong met-enkephalin-Arg6-Gly7-Leu8-like immunostaining was seen in other regions of the brain. These results suggest that in magnocellular neurons dynorphin(1-8) exists independently from pro-enkephalin and therefore the magnocellular neurons represent a third opioid peptide neuronal system in brain. These observations, however, do not rule out a coexistence of proenkephalin and dynorphin-related peptides in other regions of the brain.

A comparison of antibody capture radio- and enzyme immunoassays with immunofluorescence for detecting IgM antibody in infants with congenital rubella

IgM antibody capture radioimmunoassay (MACRIA) and enzyme immunoassay (MACEIA) were compared with immunofluorescence (IF) for detecting specific IgM antibody in 99 sera from 76 infants with confirmed congenital rubella, and 61 sera from a comparative group of 59 infants who had miscellaneous abnormalities but in whom congenital rubella was not confirmed. All of 35 specimens collected from confirmed cases within 12 weeks of birth were positive by all three methods and all but one of 17 specimens collected after the age of 18 months were uniformly negative. At intermediate ages discrepancies occurred in 18 specimens, of which eight were positive and 10 negative by IF. Three of these 18 specimens were negative by both antibody capture procedures but showed weak fluorescence; the other 15 were negative by MACEIA, but positive by MACRIA which appears to be the more sensitive of the antibody capture methods. Sera from five infants in the comparative group were clearly positive by all three methods. These five infants were probably congenitally infected with rubella. Sera from the other 54 infants were negative, except for one that gave a weakly positive result by MACRIA alone. Antibody capture procedures offer several advantages over previous methods for detecting IgM antibody. Although MACRIA was found to be slightly more sensitive than MACEIA, the greater stability of the enzyme label, together with the possibility of both visual and quantitative assessment, could make MACEIA the method of choice for detecting rubella-specific IgM.

Novel peptide neuronal system in rat brain and pituitary

Immunohistofluorescence studies of the rat central nervous system with antibodies to Phe-Met-Arg-Phe-NH2 (molluskan cardioexcitatory peptide) revealed a widespread neuronal system in the brain, spinal cord, and posterior pituitary. Immunoreactive axons and cell bodies were mainly located in cortical, limbic, and hypothalamic areas. Immunostaining of serial sections of the brain and pituitary showed that the Phe-Met-Arg-Phe-NH2 immunoreactive neurons were different from neurons labeled by antibodies to either Met-enkephalin or the putative Met-enkephalin precursor Tyr-Gly-Gly-Phe-Met-Arg-Phe, which is structurally related to Phe-Met-Arg-Phe-NH2. Control staining by antiserum absorption and radioimmunoassay indicated that the antibodies that caused the specific immunofluorescence recognized peptides with an amidated Arg-Phe sequence at the carboxyl terminus.

An in-vivo study of renal cadmium and hypertension

A comparative study of renal cadmium burdens in a group of thirty hypertensive patients undergoing treatment and in a group of thirty matched controls is reported, both groups being volunteers selected from a non-occupationally exposed population. The aim of this study was to investigate the possible involvement of cadmium in the aetiology of hypertension at the chronic low levels of environmental exposure. Renal cadmium levels were measured in vivo, using the technique of partial-body neutron activation analysis. The results showed that the mean renal cadmium level in the hypertensive group [3.3 mg (SD 2.3)], was not significantly different from that [4.4 mg (SD 2.7)], in the normotensive group. Whether the level in the hypertensives depends on the treatment is open to question and will be the subject of further investigation. In addition, the results confirm that kidney cadmium levels are elevated in smokers.

Antenatal screening in Oxford for fetal neural tube defects

Between May 1975 and the end of 1977, 6443 antenatal patients were screened mainly between 16 and 22 weeks of pregnancy for neural tube defects (NTDs) at the John Radcliffe Hospital, Oxford, by maternal serum alpha-fetoprotein (AFP) measurement; a take-up of 72 per cent. Seventeen out of 18 (94 per cent) patients with open NTD pregnancies (9 out of 9 with anencephaly and 8 out of 9 with open spina bifida) had positive screening tests, and all except one were offered and accepted a termination of pregnancy. Two hundred and forty-five (3.8 per cent) patients with unaffected pregnancies also had positive screening tests, although only 1.4 per cent had an amniocentesis. Following ultrasonography, about 50 per cent of patients with unaffected pregnancies with positive screening tests were not offered an amniocentesis because they had a multiple pregnancy or their gestational age had been underestimated. The odds of having a fetus with an NTD among the women who had an amniocentesis was about 1 to 6 (1 to 11 for open spina bifida alone). Two apparently normal pregnancies were terminated. A survey of the acceptability of the screening programme among a consecutive sample of 73 patients who knew that they had a positive screening test revealed that all except one had no objection to screening in general, and 68 (93 per cent) wanted to be tested again in a future pregnancy. The approximate direct cost of the programme was 2 pounds to 3 pounds per patient screened, or about 1000 pounds per NTD detected (about 2200 pounds per open spina bifida detected).

Cellular content of amniotic fluid as predictor of central nervous system malformations

Prospective observations on 442 consecutive samples have confirmed that pregnancies with CNS malformations are regularly associated with an abnormal cellular content of amniotic fluid. A crude semiquantitative test of the cell content can give valuable clinical information in relation to borderline amniotic fluid alpha-fetoprotein values, and help to detect false positive AFP's.

Insulin-like actions of nickel and other transition-metal ions in rat fat-cells

NiC12 (1-6mM) decreased adrenaline and glucagon-stimulated lipolysis in rat fat-cells, and also considerably stimulated [U-14C]glucose incorporation into fat-cell lipids. 2. These insulin-like effects were also observed with CuCl, CuCl2, CoCl2 and (to a lesser extent) with MnCl2. 3. NiCl2 was less effective in mimicking insulin effects on [U-14C]fructose metabolism than on glucose utilization. 4. It is tentatively suggested that these transition-metal ions may mimic actions of insulin at the fat-cell plasma membrane which decrease lipolysis and stimulate glucose transport, but do not mimic certain other effects of the hormone on intracellular metabolic processes. 5. These results are discussed with reference to suggestions that redistributions of cellular Ca2+ are associated with insulin action in fat-cells.

The dispersal of an initial concentration of motile bacteria

The dispersal of an initial concentration of identical Brownian particles is accurately described by the solution of the conventional diffusion equation, and a diffusion coefficient can be assigned to the assembly of particles. However, the dispersal of an initial concentration of motile bacteria is not well described by the same solution, in spite of the similarity between the random motion of a bacterium and a Brownian particle. Reasons for the failure of the Gaussian solution of the diffusion equation to describe the dispersal of Escherichia coli are discussed. An equation is formulated which gives the concentration of dispersing organisms as a function of space and time if the speed distribution function of the assembly of organism is known and reproduction is suppressed. For three assumed speed distributions the results are compared with concentrations measured by previous authors.

The activities and intracellular distribution of nicotinamide-adenine dinucleotide phosphate-malate dehydrogenase, phosphoenolpyruvate carboxykinase and pyruvate carboxylase in rat, guinea-pig and rabbit tissues

1. Measurements are presented of the activity and intracellular distribution of phosphoenolypruvate carboxykinase, pyruvate carboxylase and NADP-malate dehydrogenase in rat, guinea-pig and rabbit liver and kidney cortex, together with previously obtained measurements of these enzymes in adipose tissue. 2. In all three tissues pyruvate carboxylase activity was greatest in the rat and lowest in the rabbit. 3. Guinea pig and rabbit were very similar to each other with respect to the extramitochondrial-mitochondrial distribution of phosphoenolpyruvate carboxykinase in all three tissues. 4. NADP-malate dehydrogenase was present in all three tissues in the rat, present in kidney cortex and adipose tissue in the guinea pig and absent from all tissues examines in the rabbit.