[Detection of isoferritin level in breast cancer tissue and serum]

ELISA (double-determinant) was used to evaluate the isoferritin level in the breast cancer tissue. The isoferritin concentration was measured in cytosol extracts of 25 breast cancer tissues (BCT), 6 cancer surrounding tissues (CST) and 8 normal breast tissues (NBT). With the results of 16,023 +/- 15,732, 2467 +/- 1360 and 1382 +/- 647 ng/mcp (milligrams of ontosol protein), respectively. The isoferritin concentrations of BCT and CST were 11.6 and 1.8 times as much as that of NBT, and the differences were statistically significant (P < 0.001 and 0.05). The serum isoferritin level was also measured in 96 healthy persons and 68 breast cancer patients (mean 58.7 +/- 35.8 and 473.3 +/- 297.3 ng/ml) with the difference as big as 8.1 times. The results have demonstrated that the level of cytosol isoferritin in BCT is an important parameter of breast tissue malignance and may be also responsible for the serum isoferritin increase. Therefore we think that serum isoferritin may be used as a marker for early diagnosis of breast cancer.

[Biochemical effects of maternal intravenous and intra-amniotic infusion of amino-acids on fetal blood]

Before elective cesarean section, 58 normal term's pregnant women were randomly divided into three groups: intravenous (25 women), intra-amniotic (8 women) and control (25 women) groups. The first two groups received maternal intravenous and intra-amniotic infusion of amino acids respectively. The results showed that maternal intravenous administration of amino-acids led to increased levels of amino acids in maternal venous blood and fetal umbilical cord blood plasma (P < 0.05). There was no increase in fetal uptake of amino acids (P > 0.05). The levels of amino acids in fetal umbilical cord blood plasma of the intra-amniotic group were higher than those of the control group (P < 0.05) and intravenous group (P < 0.05). In the intra-amniotic group, the fetal uptake of amino acids increased (P < 0.05). There were no significant differences in fetal umbilical arterious pH, PO2 and PCO2 among the three groups (P > 0.2). Intra-amniotic infusion of 250ml amino-acids did not change the pressure of amniotic cavity (P > 0.2). The authors suggested that intra-amniotic infusion of amino acids, as a paraplacental nutritional route, should be more effective in the treatment for cases of intrauterine fetal growth retardation particularly for those accompanied by severe placental lesions.

Ionic mechanisms of electronic inhibition and concealed conduction in rabbit atrioventricular nodal myocytes

BACKGROUND

The term "concealed conduction" is used in electrocardiography when a proximal (atrial or ventricular) impulse penetrates the atrioventricular (AV) node but fails to traverse it completely. Its penetration into the node is inferred by its after effects on the propagation of succeeding impulses. Concealed AV nodal conduction is a well-established phenomenon, but its precise cellular and subcellular mechanisms are unknown. It has been suggested that concealed conduction results from a transient impairment of excitability caused by the subthreshold depolarization (ie, electrotonic inhibition) that is elicited downstream of the site of block.

METHODS AND RESULTS

We studied the ionic mechanism of electrotonic inhibition and concealed conduction in single myocytes isolated from the rabbit AV node. Cells were paced using just-threshold current pulses delivered at a constant (basic) cycle length of 1 second. Appropriately timed interpolation of a conditioning pulse of depolarizing but subthreshold current led to failure of the subsequent, previously successful activation. The ability of the subthreshold response to inhibit subsequent excitation was increased when the interval between the conditioning and succeeding pulses was shortened, when the amplitude of the conditioning pulse was increased, or when the inward sodium current was blocked by superfusion with tetrodotoxin (30 microM). Voltage clamp analysis demonstrated that electrotonic inhibition results from partial inactivation of the transient calcium current (ICa.T). Similar results were obtained using a mathematical model (Hodgkin-Huxley type) of the AV nodal myocyte. Additional simulations in a linear array of AV nodal cells showed that when a premature impulse fails to traverse the AV node, the subthreshold depolarization elicited downstream of the site of block may lead to a transient reduction of excitability with consequent delay or block of the succeeding impulse.

CONCLUSIONS

The overall data strongly suggest that some of the electrocardiographic manifestations of concealed AV conduction are the result of electrotonic inhibition of excitability secondary to a transient decrease in ICa.T.

The role of spermatozoa in the pathogenesis of Chlamydia trachomatis salpingitis in a primate model

BACKGROUND AND OBJECTIVES

The role of spermatozoa in carrying microorganisms from the cervix to the fallopian tubes and promoting infection was examined in eight pig-tailed macaques.

GOAL OF THIS STUDY

The aim of this study was to determine whether spermatozoa play a role in the transport of Chlamydia trachomatis into the upper reproductive tract and in the pathogenesis of chlamydial salpingitis.

STUDY DESIGN

Five monkeys were inoculated with Chlamydia trachomatis in the cervix and mated, and three other monkeys were infected in the cervix but not mated.

RESULTS

Culture positive results were obtained for cervical samples from all animals. After cervical inoculation, no mated animals and one unmated animal had positive culture results for samples from the fallopian tubes. After mating, no spermatozoa examined in samples taken from the upper tract or cul de sac had elementary bodies (EBs) on their surfaces, and only one sample obtained from the cervix showed C. trachomatis attached to the spermatozoa, as determined by fluorescent antibody (FA) staining. Two of the mated monkeys became pregnant; one spontaneously aborted late in gestation, and the other delivered a normal female infant. The fallopian tubes of all eight monkeys were challenged directly with serovar D and examined for evidence of salpingitis. Repeat laparoscopy was performed to monitor the inflammatory response. Tubal specimens for isolation and polymerase chain reaction (PCR) were obtained. Hysterectomies were performed between 3 and 4 weeks after tubal inoculation. Histopathologic examination of the fallopian tubes revealed widespread inflammation consisting of focal collections of lymphocytes and plasma cells in the submucosa. Peritubal adhesions were observed in four of five mated monkeys and in two of three unmated monkeys.

CONCLUSION

This study failed to confirm that spermatozoa play a role in the pathogenesis of C. trachomatis infection.

Ectopic expression and function of the Antp and Scr homeotic genes: the N terminus of the homeodomain is critical to functional specificity

The transcription factors encoded by homeotic genes determine cell fates during development. Each homeotic protein causes cells to follow a distinct pathway, presumably by differentially regulating downstream ‘target’ genes. The homeodomain, the DNA-binding part of homeotic proteins, is necessary for conferring the specificity of each homeotic protein's action. The two Drosophila homeotic proteins encoded by Antennapedia and Sex combs reduced determine cell fates in the epidermis and internal tissues of the posterior head and thorax. Genes encoding chimeric Antp/Scr proteins were introduced into flies and their effects on morphology and target gene regulation observed. We find that the N terminus of the homeodomain is critical for determining the specific effects of these homeotic proteins in vivo, but other parts of the proteins have some influence as well. The N-terminal part of the homeodomain has been observed, in crystal structures and in NMR studies in solution, to contact the minor groove of the DNA. The different effects of Antennapedia and Sex combs reduced proteins in vivo may depend on differences in DNA binding, protein-protein interactions, or both.

Ellagic acid embryoprotection in vitro: distribution and effects on DNA adduct formation

Ellagic acid (EA) is a naturally occurring plant phenol that was recently demonstrated to protect cultured rat embryos from the embryotoxic effects of N-methyl-N-nitrosourea (MNU). The teratogenic mechanism of action of MNU, as well as other methylating agents, is debated: both cell death and mutation have been proposed. In some model systems, EA has been reported to selectively decrease the mutagenic DNA adduct O6-methylguanine (O6MG) when compared to the cytotoxic DNA adduct N7-methylguanine (N7MG). The present study was initiated to determine 1) the distribution of 14C-EA and 3H-MNU in the rat whole embryo culture model system and 2) the effects of EA on MNU-induced DNA adduct formation in this model system. 14C-EA (50 microM for 2 hr, known embryoprotective concentration; no MNU added) was used to demonstrate access of EA to the embryo within the 2 hr exposure period. The majority of EA (99.5%) remained in the media while tissue concentrations of 57.0 and 47.9 pmol/mg were attained in the yolk sacs and embryos, respectively. Similarly, MNU (75 microM for 1 hr, known effective concentration; no EA added) was distributed between the media, yolk sacs, and embryos at 99.7%, 73.7 and 112.9 pmol/mg, respectively. When non-radiolabeled EA (50 microM for 2 hr) was used to protect embryos prior to exposure to 3H-MNU (75 microM for 1 hr), the distribution of MNU in the model system was unchanged.(ABSTRACT TRUNCATED AT 250 WORDS)

Simultaneous fluorescence measurement of calcium and membrane potential responses to endothelin

Vasopressin stimulates calcium signaling and chloride-dependent depolarization in glomerular mesangial cells. We describe a technique whereby both calcium and membrane potential changes can be simultaneously monitored with fluorescent probes. This technique was validated by comparison with single parameter measurements in basal and vasopressin-stimulated mesangial cells. It was shown that the calibration for calcium is unaffected by that for membrane potential, whereas the calibration for membrane potential is affected by prior calcium calibration. Accordingly, it was necessary to calibrate for the former first. The technique was then applied to investigate the effects of endothelin, which was found to elicit a concentration-dependent calcium release response and a chloride-dependent depolarization of mesangial cells. The interaction between the calcium signaling response to vasopressin and endothelin was also investigated. When vasopressin stimulation occurred subsequent to endothelin stimulation, and vice versa, a calcium response was still evident. However, these agonists displayed partial heterologous desensitization in that prior stimulation with vasopressin attenuated the subsequent response to endothelin, and vice versa. This suggests the presence of functionally distinct hormone-responsive calcium pools. The technique of double-parameter fluorescent measurement outlined could potentially be applied to other cellular signaling parameters by the use of the appropriate probes.

The actin genes of Onchocerca volvulus

The genome of Onchocerca volvulus was found to contain 2 actin gene classes (called 1 and 2) of 2 genes each. The 4 genes are located in 2 clusters (called A and B), each containing a gene class member. Five short introns of 122-207 bp occur within each gene. The sequences of the fourth intron and the 5' and 3' untranslated regions of all the 2 gene classes are completely different even though their coding regions share 95% identity. Mature transcripts from the actin genes have the nematode spliced leader (SL) at their 5' ends. One actin cDNA was found to be derived from an actin pre-mRNA which locks both the 5 introns and the 5' SL, suggesting that in at least some transcripts cis-splicing is completed before trans-splicing occurs.

Characterization of beta-adrenergic receptors in DiFi and HT-29 cells

The beta-adrenergic receptors present in two human colorectal adenocarcinoma cell lines were characterized by measuring specific binding of [125I]-cyanopindolol (CYP). Whole, cultured, DiFi (derived from a familial adenomatous polyposis [FAP] patient) and HT-29 cells were used in radioligand binding assays. Scatchard analysis of specific 125I-CYP binding gave KDS of 38.6 +/- 5.7 pM in DiFi cells and 54 +/- 9.1 pM in HT-29 cells. However, binding site density (Bmax) in the DiFi cells was greater than that in HT-29 cells. In DiFi cells, the kinetically determined KD was similar to that calculated from Scatchard analysis. Studies in DiFi cells of the displacement of specific 125I-CYP binding by nonselective (propranolol), beta 1-selective (metoprolol and atenolol), and beta 2-selective (ICI 118-551) antagonists revealed only a single class of beta 2-adrenergic receptors. This provides the first evidence that colorectal adenocarcinoma cell lines contain beta-adrenergic receptors and shows that only beta 2-adrenergic receptors are present in DiFi cells. Mechanisms possibly affecting beta-adrenergic-receptor expression in such cells are discussed in relation to colon carcinogenesis.

[ELISA of serum isoferritin and its clinical application]

Serum isoferritin levels were detected by ELISA in 96 normal, 11 cases of hepatocellular carcinoma (HCC), 28 breast cancer (BC), 31 lung cancer (LC), 26 breast fibroma, 11 pneumonia and 11 tuberculosis. The results reveal significant differences of serum isoferritin levels between the normals and the patients, and between the malignant cases and benign cases (P < 0.01). Serum isoferritin demonstrates higher sensitivity in detecting HCC, LC and BC and thus is of great value in the differential diagnosis of these cancers.

The topology of phase response curves induced by single and paired stimuli in spontaneously oscillating chick heart cell aggregates

The topological properties of the phase resetting of biological oscillators by an isolated stimulus delivered at various phases of the cycle depend on whether the stimulus is "weak" or "strong." When multiple stimuli are delivered to the oscillator, the response to stimulation also depends on the time between the stimuli, and the rate at which the oscillator returns to an underlying limit cycle attractor. If the time between two consecutive "weak" stimuli is sufficiently short, the effects produced by the pair of stimuli may be characteristic of a single "strong" stimulus. These results are demonstrated in a model experimental system, spontaneously beating aggregates of cells derived from embryonic chick heart, and are illustrated by consideration of a simple theoretical model of nonlinear oscillators, the Poincaré oscillator.

Multiple signaling pathways for Cl(-)-dependent depolarization of mesangial cells: role of Ca2+, PKC, and G proteins

We have previously reported that vasopressin activates chloride channels, leading to depolarization of glomerular mesangial cells via both calcium-dependent and calcium-independent pathways (S.G. Kremer, W.V. Breuer, and K. L. Skorecki, J. Cell. Physiol. 138: 97-105, 1989). However, the calcium-independent pathways were not defined. Using fluorescent probes, we now demonstrate that activation of protein kinase C (PKC) results in cellular depolarization in the absence of a calcium signal. This depolarization is also mediated by an enhanced conductance to chloride. Downregulation of PKC partially attenuated but did not abolish the depolarization response to vasopressin. Depolarization persisted when, in addition, calcium responses were also abolished and prostaglandin production was eliminated, suggesting an additional pathway for depolarization. G protein activation by aluminum fluoride also resulted in cellular depolarization mediated by an enhanced conductance to chloride, which persisted when calcium and PKC-signaling pathways were eliminated. This suggests the presence of a calcium- and PKC-independent pathway for G protein-mediated chloride-dependent depolarization. These findings point to the presence of at least three separate signaling pathways available for the activation of mesangial cell chloride channels, i.e., calcium, PKC, and a G protein.

[Identification of medicinal gualou (fruit-rind of Trichosanthes) and its mixed fruits in Sichuan]

Our investigation shows that in Sichuan Province there are 7 species of medicinal gualou (fruid-rind of Trichosanthes) and its confused fruits (6 species of Trichosanthes and 1 species of Citrullus), among which 2 species are included in the Chinese Pharmacopoeia. The drug and its confused fruits are similar in shape. This paper emphatically deals with the tissue identification of the above mentioned 7 species.

Primary structure and pharmacological activity of a nonapeptide related to neuromedin U isolated from chicken intestine

An extract of chicken intestine contained neuromedin U-like immunoreactivity (36 pmol/g wet tissue weight). The primary structure of the predominant molecular form (NMU-9), comprising 94% of the total immunoreactivity, was established as: Gly-Tyr-Phe-Phe-Phe-Arg-Pro-Arg- Asn-NH2. This sequence differs from that of pig neuromedin U-8 (NMU-8) by the substitution of Leu3 by Phe and, like the corresponding peptide from the guinea pig, is extended from the NH2-terminus by a Gly residue. A minor component of neuromedin U comprised 25 amino acid residues. An extract of chicken whole brain contained much less NMU-like immunoreactivity (1.5 pmol/g) and the nonpeptide was the only molecular form detected. Synthetic chicken NMU-9 produced a concentration-dependent contraction of smooth muscle from the rat uterus and its effect was unchanged in the presence of tetrodotoxin, atropine and indomethacin. The potency of chicken NMU-9 (EC50 360 +/- 60 nM; mean +/- S.E., n = 6) was approximately 8-fold less than that of pig NMU-8 (EC50 46 +/- 8 nM) but the maximum contraction produced by both agonists was not significantly different.

A comparison of trans-RNA splicing in trypanosomes and nematodes

Many aspects of the biology of kinetoplastids are unique, so it is surprising that they share with nematodes an unusual post-transcriptional process called trans-splicing. During this process, a small conserved RNA sequence is added to the 5' non-translated ends of transcribed RNAs of protein-encoding genes. Trypanosomes and nematodes are the only organisms to date in which these sequences have been described, and the biological significance of trans-splicing remains a mystery but may be of wider occurrence in invertebrates. In this review, John Donelson and Wenlin Zeng compare the process in nematodes and trypanosomes and speculate on its raison d'être.

Postnatal ontogeny of dopamine D2 receptors in rat striatum

Studies of the ontogeny of dopamine D2 receptors in rat striatum were carried out using [3H]spiroperidol as ligand in the presence of 30 nM ketanserin. D2 receptors increased with age, and saturation studies indicated that this was due to an increase in receptor density (Bmax) and not to a change in affinity (KA). By 21 days of age, receptor density had reached adult levels. Hill plots indicated no cooperativity in the binding from 7 to 21 days of age. Pharmacologically, receptors at 7, 14 and 21 days of age were similar to those of adult rats, exhibiting characteristics of dopamine D2 receptors. These studies provide a basic analysis of dopamine D2 receptors in rat striatum during early postnatal development.