In vitro evidence for atrial natriuretic factor-(5-28) production by macrophages of adult rat thymi

Although recent evidence suggests the presence of the 15-kilodalton (K) mol wt (Mr) precursor of atrial natriuretic factor (ANF) and pro-ANF mRNA in the thymus of human and rat neonates, the cellular origin of the peptides in the tissues remains to be elucidated. We report here that in adult male rats, the 15K M(r) presumptive precursor for ANF and a smaller 3K M(r), N-terminal truncated congener of the peptide, ANF-(5-28), are localized in a small population of thymic macrophages. The production of ANF in the thymus was further confirmed by demonstrating the presence of a single band of pro-ANF mRNA signal of approximately 0.8 kilobases from the tissue extract, corresponding to that in the heart. To examine the distribution of pro-ANF mRNA at a cellular level, colorimetric in situ hybridization with digoxigenin-labeled 30-mer oligonucleotides complementary to the first 10-amino acid sequence of ANF-(1-28) was employed. Positive staining was found in thymic cells localized mainly in subcapsular areas, with diffuse staining of positive cells in both the cortex and medulla mainly concentrated around the cortico-medullary junction of the tissue. The identity of the ANF-positive cells was further investigated using a double staining technique to costain immunoreactive (ir) ANF and the macrophage markers ED1 and S22 or the T-cell marker OX-19 in both thymic sections and in monolayer cultures of thymic cells. In the latter, approximately 17% of the adherent cells stained positive for irANF after 48 h in culture. Of these cells, more than 95% also stained positive for the macrophage marker ED1, whereas approximately 36% of the ED1-positive cells were colocalized with irANF. In contrast, no irANF-positive cells were colocalised with the pan-T-cell marker OX-19. In tissue sections, irANF was found in cells distributed predominantly around the cortico-medullary junctions and subcapsular areas, with diffuse staining of the cells in the medullary and cortical regions. Sephadex G-50 gel chromatographic profiles of thymic extracts revealed a major peak of immunoreactivity consistent with 15K M(r) and a smaller peak that coeluted with rat ANF-(1-28) of 3K M(r). HPLC analysis of the 3K M(r) species showed a single peak of immunoreactivity, which eluted with a retention time identical to that of synthetic rat ANF-(5-28).(ABSTRACT TRUNCATED AT 400 WORDS)

Susceptibility changes following bolus injections

The general mechanism of bulk magnetic susceptibility (BMS) induced MRI contrast following a bolus injection is elaborated. Combining radiolabeled tracer data for the first pass of a bolus injection through the human brain with the application of Wiedemann's law allows us to calculate the lower limit for the time course of the vascular BMS following the injection of any contrast agent. Superparamagnetic iron oxide particles produce a much larger effect than any mononuclear Ln(III) chelate. We also calculate the BMS changes occurring after a dilution bolus injection (of isosmolal physiological saline) subsequent to a prior slow infusion of an intravascular contrast agent. This technique bears some resemblance to the increasingly important approach that exploits changes in only the level of blood oxygenation. The calculation indicates that contrast changes after the dilution bolus injection are smaller than those following Ln(III) agent injections but larger than those due to changes in blood oxygenation and suggests a way to possibly enhance the latter. We present an in vivo study demonstrating the dilution bolus injection technique in the mouse brain, and that features its rapid repeatability. Extrapolation of these results to the human, however, indicates that the saline volumes required for venous injections, except possibly for cardiac studies, would be prohibitively large. Smaller, catheter-delivered arterial bolus injections are feasible. We also suggest a method for using an agent bolus injection to measure the parenchymal BMS, and thus the iron content, of pathologically iron-loaded tissue.

Ascorbic acid enhances forskolin-induced cyclic AMP production and pro-ANF mRNA expression of hypothalamic neurons in culture

Besides acting as an important cofactor in the biosynthesis of catecholamine, ascorbic acid (AA) also modulates the activity of peptidyl-glycine alpha-amidating monooxygenase for the post-translational modification of neuropeptides such as alpha-MSH and TRH. We report here a novel action of AA in modulating the secretion and mRNA expression of atrial natriuretic factor (ANF) in rat hypothalamic neurons. Primary cultures of hypothalamic neurons from neonatal rats as previously described were employed in the present studies. Six days after plating, cultures were replenished with serum free media and incubated with vehicle or various doses of AA, alone or in the presence of forskolin. Treatment with AA alone significantly increased irANF secretion from the cultures in a time-related and a dose-dependent manner with an ED50 of approximately 3 microM and an Emax of 100 microM. At the concentration of 10 microM, AA augmented irANF release approximately 3 fold that of the controls (55 +/- 7 pg/well; mean +/- SE, n = 3; P < 0.01), but it failed to affect the abundance of pro-ANF mRNA in the cultures. However, 10 microM of AA markedly enhanced forskolin-induced irANF secretion and pro-ANF mRNA abundance of the cultured cells. This potentiating effect of AA on forskolin stimulation showed a good parallelism to the levels of cAMP produced in the hypothalamic cultures. We thus conclude that AA acts alone or in synergism with forskolin to stimulate the secretion and production of ANF in rat hypothalamic neurons; this latter effect may operate at the genomic level and is mediated, at least in part, through the protein kinase A dependent pathway.

The determination of 5-hydroxytryptamine, related indolealkylamines and 5-hydroxyindoleacetic acid in the bovine eye by gas chromatography-negative ion chemical ionization mass spectrometry

Methods were developed for the analysis of 5-hydroxytryptamine, related indolealkylamines (tryptamine, melatonin, 5-methoxytryptamine, N-acetyl-5-hydroxytryptamine and 6-hydroxymelatonin) and 5-hydroxyindole-3-acetic acid (5HIAA) in bovine retina, aqueous and vitreous humours. 5-Hydroxytryptamine and related indolealkylamines were extracted and derivatized to form their corresponding pentafluoropropionyl spirocyclic derivatives. 5HIAA was extracted and derivatized to the corresponding pentafluoropropionamide-trifluoroethyl derivative. Identification and quantitation by gas chromatography-negative ion chemical ionization mass spectrometry was made with reference to deuteriated internal standards. 5-Hydroxytryptamine was present in all (n = 34) retinal samples analysed (20.53 +/- 1.64 ng) while N-acetyl-5-hydroxytryptamine was detected in half of the samples of retina (0.06 +/- 0.02 ng). Melatonin (0.15 +/- 0.06 ng) and tryptamine (0.78 +/- 0.34 ng) were detected in only a small number of retinas. 5-Methoxytryptamine was not present in retina. 5-Hydroxytryptamine was also present in aqueous (0.76 +/- 0.17 ng ml-1 and vitreous (0.35 +/- 0.05 ng ml-1' humours from bovine eye. Tryptamine, melatonin, 5-methoxytryptamine and N-acetyl-5-hydroxytryptamine were not detected in bovine aqueous and vitreous humours. 5HIAA was found in both bovine aqueous (2.03 +/- 0.38 ng ml-1) and vitreous (0.65 +/- 0.06 ng ml-1) humours, but its consistent determination in retina was obviated by interference from spurious peaks.

Aqueous shift reagents for high-resolution cation NMR. VI. Titration curves for in vivo 23Na and 1H2O MRS obtained from rat blood

Frequency shift/concentration calibration curves applicable to the use of shift reagents (SRs) for in vivo 23Na MRS studies can be obtained from experiments with whole blood. Here, they are reported for titrations of rat blood with the SRs DyTTHA3- and TmDOTP5-. There are a number of considerations that must be made in order to derive accurate calibration curves from the experimental data. These include the effects of bulk magnetic susceptibility (BMS, since the SRs are paramagnetic), the effects of water flux (since addition of the SR stock solution to blood renders the plasma hyperosmotic), and the consequences of restricted distribution of the SR anion in the erythrocyte suspension. We give in some detail the BMS shift theory that obtains in this case and show also how it applies to excised perfused organ as well as in vivo studies. Also, we report significant effects of adjuvant Ca2+ additions in the TmDOTP5- titrations. These are very important to the successful use of this SR in vivo. Finally, our considerations of BMS lead naturally to an understanding of its manifestations in the shifts of the 1H2O resonance frequencies of cell suspensions and tissues induced by SRs. Since these are being increasingly reported, and often misinterpreted, we devote an experiment and some discussion to this subject. We show that this phenomenon cannot be used to quantitatively discriminate intra- and extracellular 1H2O signals.

Considerations for High Frame Rate Operation of Two-Dimensional a-Si:H Imaging Arrays

Large area, two-dimensional, amorphous silicon arrays are under development for x-ray imaging applications. Theoretical limits on frame rates imposed by array design and operational requirements are examined. Measurements of image lag as a function of frame rate are reported.

Localization of DNA topoisomerase II in Chinese hamster fibroblasts by confocal and electron microscopy

The localization of the 170- and the 180-kDa isoforms of the enzyme DNA topoisomerase II in growing Chinese hamster fibroblasts has been studied by confocal immunofluorescence microscopy and immunogold electron microscopy after labeling with affinity-purified isoform-specific polyclonal antibodies. Immunofluorescence and immunogold studies, together with quantitative image analysis, show that the two isoforms are present in the nucleoplasm and in the nucleolus. In the nucleoplasm both isoforms are frequently localized at the periphery of heterochromatin regions. In the nucleolus the immunofluorescence and immunogold signals relative to surface area are higher than in the nucleoplasm; both isoforms are localized predominantly in the fibrillar zones. During mitosis both isoforms remain detectable in the cytoplasm. The differential expression of the two isoforms during the cell cycle, observed in other studies, suggests that they have different functions, and their presence in both the nucleoplasm and the nucleolus suggests that these functions are required in both of these nuclear compartments.

Photoresponse Linearity of a-Si:H Imaging Pixels

Amorphous silicon imaging arrays with ∼3×105 pixels have recently been developed and x-ray images of low contrast anatomical phantoms have been demonstrated. This paper reports on the linearity of response of these a-Si:H imaging pixels as a function of reverse bias voltage. The fraction of the imaging pixel's full signal range that maintains a linear response has been found to increase with increasing voltage.

Mechanism of action of developmentally regulated sea urchin inhibitor of eIF-4

The developmentally regulated inhibitor of eIF-4 function found in unfertilized sea urchin eggs has been partially purified and its mechanism of action studied in vitro using purified recombinant eIF-4 alpha and cell-free translation systems. The results demonstrate that although the phosphorylation of eIF-4 alpha is necessary to promote protein synthesis, it is not sufficient to maintain all aspects of eIF-4 function. The egg inhibitor does not change eIF-4 alpha phosphorylation state. During the blockage of initiation caused by the egg inhibitor, eIF-4 alpha remains phosphorylated but accumulates in a 48S initiation intermediate. This suggests that the egg inhibitor functions by preventing the release of eIF-4 alpha from the small ribosomal subunit. The characteristics of the inhibitor in a reticulocyte translation system demonstrate that eIF-4 activity is inhibited within 3-6 min. However, the inhibitor's characteristics in a mRNA-dependent translation system contrast with this. Preincubation with the inhibitor for 5-25 min prior to the addition of mRNA does not prevent endogenous eIF-4 from participating in translation but diminishes its ability to be reutilized, consistent with the accumulation of eIF-4 alpha on the small ribosomal subunit. The ribosomal localization of the inhibitor suggests that it could prevent eIF-4 alpha release by direct binding. The gradual inactivation of the inhibitor following fertilization indicates that it represents a component of a novel regulatory cascade that modulates eIF-4 activity.

Protective effects of berberine and phentolamine on myocardial reoxygenation damage

The protective effects of berberine and phentolamine against anoxia and reoxygenation damage in isolated rat hearts have been investigated. Incorporation of berberine (24.5 mumol/L) in both anoxic and aerobic perfusion media resulted in a significant reduction of CPK release during the reoxygenation period, and the ultrastructural damage was reduced as compared with the control group; the myocytes in the berberine-treated group displayed mild intracellular edema, well-registered myofibrils without contracted bands, and swollen mitochondria with partially broken cristae but without dense bodies. Berberine did not inhibit calcium and sodium accumulation or magnesium and potassium loss. Treatment with phentolamine (6.6 mumol/L), an alpha-adrenoceptor antagonist, had similar effects, though the CPK release profile was shifted to the right and downwards. These results suggest that although berberine and phentolamine have some beneficial effects on myocardial reoxygenation injury, they may not abolish the injury. Therefore alpha-adrenoceptor stimulation may not be the major mechanism behind the injury.

Catalytic properties of the human cytochrome P450 2E1 produced by cDNA expression in mammalian cells

A full-length cDNA encoding human cytochrome P450 2E1 was expressed in mammalian cell lines using the vaccinia virus expression system. Immunoblot analysis showed that the expressed protein reacted with a polyclonal antibody against rat 2E1 and comigrated with P450 2E1 from human liver microsomes. P450 2E1 expressed in Hep G2 cells, a human cell line which contains both cytochrome b5 and NADPH:P450 oxidoreductase, was able to metabolize several known P450 2E1 substrates: N-nitrosodimethylamine (NDMA), N-nitrosomethylbenzylamine (NMBzA), p-nitrophenol, phenol, and acetaminophen. Apparent Km and Vmax values for NDMA demethylation were 22 microM and 173 pmol/min/mg microsomal protein, respectively. P450 2E1 expressed in TK-143 cells, which do not contain b5, displayed Km and Vmax values of 31 microM and 34 pmol/min/mg microsomal protein, respectively. Incorporation of purified rat liver b5 into TK-143 microsomes increased the Vmax 2.2-fold and decreased the Km to 22 microM. Addition of b5 to Hep G2 microsomes resulted in a 1.6-fold increase in Vmax, but showed no effect on the Km. P450 2E1 expressed in Hep G2 cells was shown to metabolize NMBzA with a Km of 47 microM and Vmax of 213 pmol/min/mg microsomal protein. Addition of b5 lowered the Km to 27 microM, but had no effect on Vmax. These results demonstrate conclusively that P450 2E1 is responsible for the low Km forms of NDMA demethylase and NMBzA debenzylase observed in liver microsomes and that these activities are affected by cytochrome b5.

Demonstration of megavoltage and diagnostic x-ray imaging with hydrogenated amorphous silicon arrays

Flat-panel imagers consisting of the first large area, self-scanning, pixelated, solid-state arrays made with hydrogenated amorphous silicon (a-Si:H) are under development by the authors for applications in diagnostic x-ray and megavoltage radiotherapy imaging. The arrays, designated by the acronym MASDA for multi-element amorphous silicon detector array, consist of a two-dimensional array of a-Si:H photodiodes and thin-film transistors and are used in conjunction with scintillating materials. Imagers utilizing MASDA arrays offer a variety of advantages over existing technologies. This article presents initial megavoltage and diagnostic-quality x-ray images taken with several such arrays including the first examples of anatomical-phantom images. The external readout electronics and imaging techniques required to obtain such images are outlined, the construction, operation, and advantages of the arrays briefly reviewed, and the future potential of this new technology discussed.

Detection of antigens associated with lung carcinoma in sera by monoclonal antibodies WLA-2C4 and CL-3

The levels of tumor-associated antigens (TAAS) corresponded to monoclonal antibodies WLA-2C4 and CL-3 in sera of 57 lung cancer patients, 100 healthy adults and 50 non-tumor disease patients were assayed with SABC-ELISA of immunobinding inhibition test. The threshold values of WLA-2C4 and CL-3 (RBI) were 12% and 36%, respectively. The positive results of lung carcinomas with at least one of the two TAAS were as follows: squamous cell carcinoma 89%; adenocarcinoma 83%; small cell carcinoma 67% and their mean positive rate was 79%. Whereas the positive rate in healthy adults and non-tumor disease patients was only 6%. These results indicate that using monoclonal antibodies WLA-2C4 and CL-3 simultaneously may be helpful to the serological diagnosis of lung carcinoma.

Inactivation of the protein phosphatase 2A regulatory subunit A results in morphological and transcriptional defects in Saccharomyces cerevisiae

We have determined that TPD3, a gene previously identified in a screen for mutants defective in tRNA biosynthesis, most likely encodes the A regulatory subunit of the major protein phosphatase 2A species in the yeast Saccharomyces cerevisiae. The predicted amino acid sequence of the product of TPD3 is highly homologous to the sequence of the mammalian A subunit of protein phosphatase 2A. In addition, antibodies raised against Tpd3p specifically precipitate a significant fraction of the protein phosphatase 2A activity in the cell, and extracts of tpd3 strains yield a different chromatographic profile of protein phosphatase 2A than do extracts of isogenic TPD3 strains. tpd3 deletion strains generally grow poorly and have at least two distinct phenotypes. At reduced temperatures, tpd3 strains appear to be defective in cytokinesis, since most cells become multibudded and multinucleate following a shift to 13 degrees C. This is similar to the phenotype obtained by overexpression of the protein phosphatase 2A catalytic subunit or by loss of CDC55, a gene that encodes a protein with homology to a second regulatory subunit of protein phosphatase 2A. At elevated temperatures, tpd3 strains are defective in transcription by RNA polymerase III. Consistent with this in vivo phenotype, extracts of tpd3 strains fail to support in vitro transcription of tRNA genes, a defect that can be reversed by addition of either purified RNA polymerase III or TFIIIB. These results reinforce the notion that protein phosphatase 2A affects a variety of biological processes in the cell and provide an initial identification of critical substrates for this phosphatase.

Oxygen dissociation curve in the adult respiratory distress syndrome

The oxygen tension for half saturation (P50) was determined for venous blood in thirteen patients with the adult respiratory distress syndrome undergoing intensive therapy. The mean value for P50 was found to be significantly lower than the value found in ten normal control subjects (22.9 mmHg and 26.7 mmHg respectively; t = 3.03, P < 0.01). The extent of reduction in P50 was not related to serum phosphate level nor was it a predictor of short-term outcome. It is unlikely that the slight left-shifted oxygen-haemoglobin dissociation curve contributes in a major way to an oxygen delivery deficiency and its cause is unexplained.

A rational design of synthetic peptide vaccine with a built-in adjuvant. A modular approach for unambiguity

We describe a peptide vaccine model containing a built-in adjuvant. This model used a multiple antigen peptide system (MAPS) to amplify peptide antigens and a lipoamino acid, tripalmitoyl glyceryl cysteine (P3C), as a built-in adjuvant. An 18-residue peptide antigen (B2) derived from the third variable domain (amino acid 312-329) of the glycoprotein gp120 of type I human immunodeficiency virus (HIV-1) was used in this model. This peptide antigen is a suitable target since it consists of neutralizing, T-helper, and T-cytotoxic epitopes. The peptide antigen in a tetravalent MAPS format (B2M-P3C) with a lipophilic attachment was synthesized by two routes for comparison: a direct stepwise approach and an indirect modular approach. In the stepwise approach, each residue was sequentially added to the peptide resin to give B2M-P3C and the P3C was incorporated to the side chain of a carboxyl terminal lysine as Fmoc-Lys(P3C). In the modular approach, a module containing a chloroacetylated core matrix of MAPS (M-P3C) with a carboxyl tetrapeptide bearing Lys(P3C) and a second module containing the peptide antigen B2 with a cysteine at its terminus were synthesized and purified separately, and then coupled to each other to form B2M-P3C. In the modular approach, the molecular ion of B2M-P3C was unambiguously identified by ion-spray mass spectrometry. B2M-P3C, administered in liposomes without any adjuvant such as Freund's complete adjuvant, was used to immunize mice and found to induce gp120-specific antibodies in vitro, and prime cytotoxic T lymphocytes in vivo.(ABSTRACT TRUNCATED AT 250 WORDS)

Plasticity of adrenoceptor responsiveness on irANP secretion and pro-ANP mRNA expression in hypothalamic neuron cultures: modulation by dexamethasone

Atrial Natriuretic Peptide (ANP) or its smaller congeners are produced and secreted from the rat hypothalamus. Whereas immunoreactive (ir)ANP secretion and proANP mRNA expression in hypothalamic cell cultures of neonatal rats were augmented by norepinephrine acting through its alpha 2-adrenoceptors (AR), in the perifusion studies of adult hypothalamic fragments beta-AR was involved in the upregulation of irANP release. Here, we report that dexamethasone (DM) modulates irANP secretion and pro-ANP mRNA expression from hypothalamic neurons in culture by switching the adrenoceptor responsiveness of the cells from alpha 2- to that of beta-AR. In long term cultures of hypothalamic cells, treatment with clonidine (alpha 2-AR agonist) increased irANP secretion in a dose related manner. This effect of clonidine was abolished by DM, a glucocorticoid which by itself had little effect on the basal release of irANP. In contrast, isoprenaline, a beta-AR agonist which was ineffective when applied alone, enhanced irANP secretion from hypothalamic cultures in the presence of DM. Concurrent incubation of DM (5 nM) and isoprenaline (10 microM) augmented irANP release approximately 3 fold above that of cultures treated with DM alone (22.6 +/- 2.2; mean +/- SE, n = 4). However, phenylephrine, an alpha 1-AR agonist alone or in the presence of DM failed to stimulate irANP release. These immunoassay findings were accompanied by corresponding changes in the abundance of pro-ANP mRNA in the cultures as examined by colorimetric Northern blot analysis employing a 30 mer oligonucleotide probe corresponding to the first 10 amino acid sequence of rANP1-28. We conclude from the above observations that glucocorticoids modulate irANP secretion and pro-ANP mRNA expression in hypothalamic neurons by altering the responsiveness of the cells from alpha 2-AR to that of beta-AR.

A solid phase extraction technique for the isolation and identification of opiates in urine

A quantitative method was developed for the simultaneous analysis of morphine, codeine, hydromorphone, hydrocodone, and oxycodone in urine by gas chromatography/mass spectrometry. Samples were hydrolyzed with beta-glucuronidase and then extracted by solid phase extraction on Bond Elute Certify cartridges at pH 6.8. Nalorphine was used as the internal standard. The opiates were analyzed by full-scan electron impact GC/MS after derivatization with acetic anhydride-pyridine. The standard curves for all five drugs were linear between 50 and 1000 ng/mL, with correlation coefficients exceeding 0.99. Coefficients of variation were less than 7%. The method was applied to the analysis of postmortem urines positive by EMIT opiate assay, and the effect of the hydrolysis procedure on recovery of each drug was measured. The results indicate that the hydrolysis procedure is effective in increasing the recovery of all five drugs from urine. The described method enables the laboratory to identify the five opiates most commonly encountered in forensic and clinical laboratories. Its sensitivity for all five drugs is well below GC/MS cutoffs for codeine and morphine employed in NIDA laboratories, and it provides for conclusive full-scan drug identification.

In vitro evidence for modulation of morphological and functional development of hypothalamic immunoreactive atrial natriuretic peptide neurons by cyclic 3',5'-adenosine monophosphate

In the hypothalamus of the rat, the precursor of atrial natriuretic peptide (ANP) is produced and processed into its smaller congeners of 3K mol wt species, which are secreted from neurons with cell bodies in the periventricular areas and the paraventricular nuclei of the tissue. Employing long term monolayer cultures of neonatal rat hypothalamic cells, we have identified a small population of cells that stained positive for immunoreactive (ir) ANP. Seventy-two +/- 7% (mean +/- SE; n = 4 per 1000 cells) of the irANP positive cells were colocalized with the staining of neuron-specific enolase; some of the cells possessed multiple neurites and showed irANP staining in the perikarya, in the varicosities along neuronal processes, and at the terminals of long neurites. Over the range of 10(-6)-10(-4) M, forskolin, 3-isobutyl-1-methylxanthine, or 8-bromo-cAMP significantly augmented the total number of irANP-positive cells and those possessing neurites in a dose-related and time-dependent manner. At 10(-4) M, 4 days of forskolin treatment increased the number of irANP-positive neurons 4-fold (P less than 0.01) while tripling that of the cells with long neurites (P less than 0.01). Furthermore, it approximately tripled the number of cells (P less than 0.01) showing positive signals for pro-ANP mRNA, as ascertained by colorimetric in situ hybridization using a 30-basepair antisense oligonucleotide probe labeled with digoxigenin. Consistent with the above observation, forskolin, 3-isobutyl-1-methylxanthine, or 8-bromo-cAMP treatment significantly augmented the total amount of irANP present in the cultures, with an ED50 of forskolin approximating 5 x 10(-5) M. Although treatment with 10(-7) M phorbol 12-myristate 13-acetate approximately doubled the production of irANP in the cultures (P less than 0.05), phorbol 12-myristate 13-acetate had little effect on modulating the number or neurite outgrowth of irANP neurons. Thus, our present findings suggest that protein kinase-A pathways are of greater importance than protein kinase-C pathways in regulating both the functional and morphological development of ANP-producing neurons during the ontogenesis of the rat hypothalamus.

Evidence for atrial natriuretic peptide-(5-28) production by rat placental cytotrophoblasts

Atrial natriuretic peptide (ANP), a 28-amino acid peptide, is produced and secreted by cardiac atriocytes to modulate cardiovascular and renal functions. We report here the production of ANP-(5-28) and its 15K mol wt (M(r)) presumptive precursors by cytotrophoblasts of rat placentae. Placental tissues were collected from Sprague-Dawley fetal rats on days 12, 16, 18, and 20 of gestation and acid extracted for immunoreactive (ir) ANP assay. The contents of placental irANP increased over the course of fetal growth, with the highest amount (mean +/- SE, 1083 +/- 125 pg/tissue; n = 7) found near term. Sephadex G-50 gel chromatographic profiles of the placental extract revealed a major peak of irANP coeluted with the 3K M(r) of synthetic rat (r) ANP-(1-28) and a minor peak in the position consistent with that of 15K M(r). HPLC analysis of the 3K M(r) species showed a single peak of immunoreactivity, which eluted with a retention time similar to that of rANP-(5-28). In placental sections, irANP and pro-ANP mRNA were localized by immunoperoxidase staining and colorimetric in situ hybridization in a subpopulation of placental cytotrophoblasts, but not in syncytiotrophoblasts or chorionic cells. Northern blot analysis showed a single band of pro-ANP mRNA in rat placental tissues similar in size to that found in the heart (approximately 0.85 kilobases), with the highest level of pro-ANP mRNA signal detected in the placentae of 16-day gestation fetuses. Our findings suggest that ANP is expressed and produced by a small population of rat placental cytotrophoblasts and that the 15K M(r) precursor peptide is extensively processed into the N-terminal-truncated form of ANP-(5-28) in the tissue.

[Application of the regression orthogonal design to the fertilization of Psoralea corylifolia L. for optimum yield]

This paper probes into the determination of the optimum amount of fertilization by applying regression orthogonal design. After a significance test by regression equation, a regression equation can be set up, i. e. Y = 25.21 + 9.18 Xn + 15.68 Xp - 0.4 Xn2 - 0.98 Xp2 + 0.062 Xn Xp. This equation can be used to describe the relationship between yield and amount of fertilization.