Dietary trace elements and esophageal cancer mortality in Shanxi, China

To explore the relation between esophageal cancer and dietary trace elements in humans, we estimated the average daily intake of zinc, copper, iron, selenium, molybdenum, silicon, cadmium, and nickel in 21 Chinese communes, where the annual mortality rate from esophageal cancer among the population 30 years of age and over ranged from 0 to 495/100,000 person-years. We also estimated the relative level of calcium consumption. Zinc and copper intake were inversely related to esophageal cancer mortality, and calcium intake levels was positively related to esophageal cancer mortality. The predicted esophageal cancer mortality among a vegetarian population with a high level of dietary calcium and a low level of dietary zinc was 5.3 times as high as that in a vegetarian population with a low level of dietary calcium and a high level of dietary zinc. The influence of a high level of dietary calcium in a vegetarian population may be explained by a reduction in the absorption of dietary zinc.

ATP-sensitive potassium channels in neonatal and adult rabbit ventricular myocytes

The properties of the ATP-sensitive potassium (KATP) current were studied in freshly isolated rabbit ventricular myocytes using the patch clamp technique. Removing ATP from the bath (intracellular) solution activated a large K+ conductance in patches from neonatal cells with properties similar to those of KATP channels in other preparations. In membrane patches from neonatal ventricular myocytes, the density of KATP channels was higher than the density of inwardly rectifying K+ channels and the mean patch KATP current was approximately 10 times that of the inwardly rectifying K+ current, at a patch membrane potential of -60 mV. Glibenclamide (10 microM) in the bath solution decreased the number of functional KATP channels, the open-state probability, and the mean patch membrane current. The single-channel conductance of the KATP channel was dependent on the external K+ concentration, and the relationship between channel conductance and external K+ concentration was fit by an exponential equation. In addition, the voltage dependence, channel density, and open-state probability of this channel were compared between neonatal and adult isolated ventricular myocytes. The single-channel conductance and channel density of the KATP channel in neonatal myocytes were significantly smaller than in adult cells. These results suggest that age-related changes occur in the properties of KATP channels.

Lipid peroxidation in experimental uveitis: sequential studies

Previously we have detected the occurrence of retinal lipid peroxidation initiated by phagocyte-derived oxygen radicals in experimental autoimmune uveitis (EAU). In the current studies, the confirmation of inflammation-mediated lipid peroxidation was proceeded further to include measurement of multiple parameters, including conjugated dienes, ketodienes, thiobarbituric acid reactive substances and fluorescent chromolipids. The assay for myeloperoxidase, a measure for the number of polymorphonuclear leukocytes in the inflammatory sites was also carried out. The levels of all these parameters were followed through the course of EAU development. The sequential evaluation of histologic changes using both light and electron microscopy was also carried out and the results were correlated with lipid peroxidation indices. These data suggest that the retinal lipid peroxidation plays a causative role in the subsequent retinal degeneration.

The carboxy-terminal region of the glycoprotein hormone alpha-subunit: contributions to receptor binding and signaling in human chorionic gonadotropin

The glycoprotein hormones are heterodimeric and contain a common alpha-subunit, which is noncovalently associated with a hormone-specific beta-subunit. The alpha-subunit has been highly conserved throughout evolution; for example, the five amino acid residues of the carboxy-terminus, Tyr-Tyr-His-Lys-Ser-COOH, are identical in nine of the 10 available amino acid sequences. It has been shown that enzymatic removal of these five amino acid residues, while not affecting holoprotein formation, results in a heterodimer that exhibits very little, if any, binding to the CG/LH receptor. Using site-directed mutagenesis on the human alpha-subunit, we have prepared two deletion mutants, Des-(88-92)alpha and Des-(89-92)alpha, and two point mutants, where each of the two tyrosines, 88 and 89, was replaced with phenylalanine, in order to delineate more specifically the contributions of these aromatic side-chains to receptor binding. The cDNAs for wild-type hCG alpha and mutants were introduced into a pcDNAINEO expression vector, and the cDNA for hCG beta was inserted into a pRSV plasmid; both were transiently cotransfected into DUXB-11 cells. The media were collected, and RIAs showed that all mutants formed heterodimers; moreover, there was no discernable difference in subunit assembly between wild-type hCG alpha and the various mutant alpha-subunits. The gonadotropin mutants were assayed in vitro using a competitive binding assay with [125I]hCG and stimulation of progesterone production in the transformed murine Leydig cell line MA-10.(ABSTRACT TRUNCATED AT 250 WORDS)

Two human liver cDNAs encode UDP-glucuronosyltransferases with 2 log differences in activity toward parallel substrates including hyodeoxycholic acid and certain estrogen derivatives

Two human liver UDP-glucuronosyltransferase cDNA clones, HLUG25 [Jackson, M. R., et al. (1987) Biochem. J. 242, 581-588] and UDPGTh-2 [Ritter, J. K., et al. (1990) J. Biol. Chem. 266, 7900-7906] have previously been shown to encode isozymes active in the glucuronidation of hyodeoxycholic acid (HDCA) and certain estrogen derivatives (estriols and 3,4-catechol estrogens), respectively. Here we report that the UDPGTh-2-encoded isoform (udpgth-2) and the HLUG25-encoded isoform (udpgth-1) have parallel aglycon specificities. Following expression in COS-1 cells, each isoform metabolized three types of dihydroxy- or trihydroxy-substituted ring structures, including the 3,4-catechol estrogen (4-hydroxyestrone), estriol and 17-epiestriol, and HDCA, but the udpgth-2 isozyme is 100-fold more efficient than udpgth-1. udpgth-1 and udpgth-2 are 86% identical overall (76 differences out of 528 amino acids), including 55 differences in the first 300 amino acids of the amino terminus, a domain which confers isoform substrate specificity. The data indicate that a high level of conservation in the amino terminus is not required for the preservation of substrate selectivity. Analysis of glucuronidation activity encoded by UDPGTh-1/UDPGTh-2 chimeric cDNAs constructed at their common restriction sites, SacI (codon 297), NcoI (codon 385), and HhaI (codon 469), showed that nine amino acids between residues 385 and 469 are important for catalytic efficiency, suggesting that this region represents a domain which is critical for catalysis but distinct from that responsible for aglycon selection.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of lipid peroxides and superoxide dismutase on systemic lupus erythematosus: a preliminary study

Serum lipid peroxide (LPO) levels, superoxide dismutase (SOD) activity in peripheral blood erythrocytes, serum ANA, anti-dsDNA, and C3 were measured in 83 patients with systemic lupus erythematosus (SLE) and in 29 healthy controls. Compared to the controls, LPO levels were significantly increased in active SLE patients while SOD activity was markedly decreased. From the active phase to the inactive phase, a gradual decline in LPO levels and an increase in SOD activity were observed. There was a close correlation between LPO levels and disease activity or the parameters including ANA titers, anti-DNA titers, and C3 levels; a significant negative correlation was found between SOD activity and LPO levels or these parameters. Further, a marked difference in SOD activity was found in untreated active cases with and without nephritis. As the SLE patients improved, LPO levels gradually declined and SOD activity increased. The present study indicates that free radicals and resultantly formed lipid peroxide levels are higher in patients with SLE than those in normal persons, probably contributing to the production of autoantibodies, nephritis, and vasculitis of other organs, and that excessively generated free radicals may play an important role in the pathogenesis of SLE, which is possibly due to diminished SOD activity.

Availability of the B beta(15-21) epitope on cross-linked human fibrin and its plasmic degradation products

The binding of radiolabeled monoclonal antifibrin antibody 59D8 (specific for fibrin but not fibrinogen) to a series of degraded fibrin clots showed that the availability of the B beta(15-21) epitope (against which 59D8 had been raised) was inversely proportional to the extent of clot lysis. Examination of digest supernatants revealed that the B beta(15-21) epitope was released from clots as a high molecular weight degradation product in the presence of calcium ions but that the generation of low molecular weight peptides occurred in the absence of calcium ions. To address the question of epitope accessibility, we compared levels of fibrin clot binding among four radioactively labeled antibodies: antifibrin monoclonal antibody 59D8, two antifibrinogen monoclonal antibodies that cross-reacted with fibrin, and an affinity-purified polyclonal antifibrinogen antibody. We expected that the antifibrinogen antibodies would show enhanced binding to clots in comparison with the antifibrin antibody. However, the epitope accessibility experiments showed that all four antibody preparations bound fibrin clots at comparable levels. Taken together, these studies demonstrated that one fibrin-specific epitope, B beta(15-21), remains available on clots as they undergo degradation by plasmin and, importantly, that the epitope is not solubilized at a rate faster than the rate at which the clot is itself solubilized. The availability of the B beta(15-21) epitope during the course of plasminolysis assures the potential utility of antifibrin antibodies such as 59D8 for detecting thrombi and targeting plasminogen activators.

Developmental changes in membrane Ca2+ and K+ currents in fetal, neonatal, and adult rabbit ventricular myocytes

Whole-cell calcium current (ICa) and inwardly rectifying potassium current (IK1) were studied in 21-day fetal, 28-day fetal (total gestation, 31 days), 2-5-day neonatal, and adult rabbit ventricular myocytes isolated by enzymatic dissociation. Whole-cell peak ICa and IK1 at -100 mV increased significantly after birth. Cell size approximated from cell membrane capacitance also increased with age, with the most significant increase occurring after birth. When normalized to cell surface area, peak ICa density increased from day 21 of gestation to the neonate and then increased again from neonate to adult. In all age groups, peak ICa occurred at a test potential of +10 mV, and the shape of the Ca2+ current-voltage relation did not change with age. These findings suggest that there are no significant developmental changes in the voltage dependence of ICa. Therefore, the measured age-related increase in Ca2+ current density may result from increased channel expression. IK1 also exhibited a pattern of increasing current density with age. For IK1, the increase in current density was most rapid between day 21 and the perinatal period and much slower after birth. These results demonstrate that ICa and IK1 undergo significant changes during late fetal and postnatal development.

Determination of procaine in equine plasma and urine by high-performance liquid chromatography

The variability in plasma and urine equine procaine measurement between three independent laboratories using current methods led to the development of a sensitive, reliable, and reproducible high-performance liquid chromatographic method. Standardbred mares were administered either a penicillin G procaine preparation intramuscularly or procaine hydrochloride subcutaneously, and blood and urine were collected at defined time intervals. By HPLC the detection limits for procaine in plasma and urine were 1 and 10 ng/mL, respectively. In contrast procaine in plasma could not be detected by GC-NPD, while the urinary detection limit was 50 ng/mL. The concentration of fluoride in the collection tubes and repetitive freeze-thawing modified plasma procaine measurement. Urinary pH was a factor in estimation of urine procaine levels with greater recovery and reproducibility of results at pH 5 as compared to pH 7. This HPLC method provides a simple, sensitive, and reliable quantitation of procaine in equine plasma and urine.

A novel complex locus UGT1 encodes human bilirubin, phenol, and other UDP-glucuronosyltransferase isozymes with identical carboxyl termini

Two human liver UDP-glucuronosyltransferase (transferase) cDNAs, HUG-Br1 and HUG-Br2, were previously isolated (Ritter, J. K., Crawford, J. M., and Owens, I. S. (1991) J. Biol. Chem. 266, 1043-1047), and each was shown to encode a bilirubin transferase isozyme which catalyzes the formation of all physiological conjugates of bilirubin IX alpha following expression in COS-1 cells. Sequence data showed that the cDNAs contained identical 3' ends (1469 base pairs in length) to each other and to that of the human phenol transferase cDNA, HLUG P1 (Harding, D., Fournel-Gigleux, S., Jackson, M. R., and Burchell, B. (1988) Proc. Natl. Acad. Sci. U.S.A. 85, 8381-8385). Here we report that the two corresponding bilirubin transferases and the phenol transferase are encoded by a novel locus, UGT1, which is also predicted to encode three other bilirubin transferase-like isozymes all having identical carboxyl termini. The transcriptional arrangement utilizes six nested promoter elements, each of which is positioned upstream of a unique exon 1. Each exon 1 encodes the NH2-terminal domain (286 amino acids) and confers the substrate specificity of the isoform. The 3' end of the locus contains 4 common exons which encode the identical carboxyl termini (246 amino acids). It is predicted that six nested primary transcripts are synthesized and that each exon 1 is differentially spliced to the 4 common exons to produce six unique, mature mRNAs. Although the gene organization is present as a single copy, it provides the flexibility of independent regulation of each isoform which is known to occur in the case of bilirubin and phenol transferase activities. With an understanding of the gene structure, lethal, as well as the nonlethal defects, associated with bilirubin transferase activity can now be determined.

A single amino acid residue replacement in the beta subunit of human chorionic gonadotrophin results in the loss of biological activity

The heterodimer, human chorionic gonadotrophin (hCG), contains an alpha subunit that is common to the glycoprotein hormones and a hormone-specific beta subunit. A comparison of all known beta amino acid sequences shows that an aspartic acid at position 99 (with the numbering scheme for hCG-beta) is one of the seven non-Cys invariant residues. Using site-directed mutagenesis we have replaced hCG-beta Asp99 with Arg. Chinese hamster ovary cells, containing a stably integrated gene for bovine alpha subunit, were transiently transfected with plasmids containing wild-type and mutant hCG-beta cDNAs. The Arg99 beta mutant associated with the alpha subunit, but the resulting heterodimer failed to enhance intracellular cyclic AMP production in a gonadotrophin-responsive transformed murine Leydig cell line. Thus, a single amino acid residue replacement in this glycosylated heterodimer containing 237 amino acid residues is sufficient to abolish activity.

A double (exchange transfusion-carbon clearance) model for testing post-resuscitation reticuloendothelial function

A double exchange transfusion-double carbon clearance method was evaluated for assessing reticuloendothelial (RE) function following exchange transfusion with hemoglobin solutions. Fifty percent of estimated blood volume (3% body weight) was withdrawn from anesthetized Sprague-Dawley rats and isovolumically replaced with shed blood (SB, control), lysed shed blood (LB, pos. control), human stroma-free hemoglobin solution (SFH), or polyhemoglobin solution (PHS). Thirty minutes after the exchange transfusion, colloidal carbon was injected intravenously and its vascular clearance followed for 1 hour. Then, the 50% exchange transfusion was repeated and the second carbon clearance measured. The intravascular carbon clearance constants, K, and clearance half-times, T1/2, were calculated and compared. No apparent differences in RE function were seen among the groups after the initial exchange transfusion. However, following the second exchange transfusion significant (P less than 0.05) slowing of carbon clearance was observed in lysed blood treated animals. The RE function of SFH or PHS treated animals were not different (P less than 0.05) from that of SB animals. A double exchange transfusion-double carbon clearance method seems to reveal changes in RE function that are not apparent after a single exchange transfusion and clearance test.

Antigen-specific suppressor cells in experimental autoimmune uveitis

Anti-I-A antibodies, administered in vivo at the time of S-antigen injection, suppress development of experimental autoimmune uveitis (EAU) in Lewis rats. While the effects of anti-I-A are profound, the exact mechanism for this suppression is unknown. We attempted adoptive transfer of this form of suppression by injecting lymphocytes from anti-I-A-treated animals into syngeneic recipients which were later injected with S-antigen. Histologically, globes of 75% of the anti-I-A-treated animals showed no inflammation while 25% of these animals developed mild uveitis. In the group of animals which were injected with S-antigen and also received spleen cells from anti-I-A-treated rats, only 1 showed mild uveitis while the remaining 7 had no inflammation. The animals undergoing adoptive transfer of spleen cells and which were primed with an irrelevant antigen, readily developed uveitis. Suppression of S-antigen-induced EAU was abrogated by pretreatment of donor animals with cyclophosphamide. In vitro studies revealed that spleen cells of S-antigen-primed, anti-I-A-treated donors specifically suppressed lymphocyte responses to S-antigen. These in vivo and in vitro results suggest that generation of antigen-specific suppressor cells play a role in the anti-I-A immunotherapy of EAU.

Hepatic reticuloendothelial function following resuscitation with hemoglobin solutions

Red cell substitutes could lead to depressed reticuloendothelial (RE) particulate clearance function. This hypothesis was tested using an animal model of hypovolemia-resuscitation. Anesthetized male Sprague-Dawley rats were subjected to 50% blood volume hemorrhage followed by isovolumic replacement with stroma-free hemoglobin (SFH, 7 gHb/dl), polyhemoglobin (PHS, 14 gHb/dl), or shed blood (SB). At 30 min post-transfusion, the liver was isolated and perfused with colloidal carbon. Hepatic RE function was assessed from the carbon clearance kinetics. In separate experiments, the hepatic Kupffer cells were isolated and cultured from rats that were previously hemorrhaged and transfused with normal saline solution. The cultured Kupffer cells were incubated with SFH or bovine albumin (ALB) and their phagocytic function assessed in-vitro. The hepatic carbon clearance following exchange transfusion with hemoglobin solutions was not significantly altered as compared to shed blood controls (P greater than 0.05). Similarly, phagocytic function of hemoglobin treated Kupffer cells was not significantly different (P greater than 0.05) from that of ALB treated cells.

A sensitive fluorometric assay for reducing sugars

A simple and rapid fluorometric assay for reducing sugars that is sensitive to the nanomolar range has been developed. The assay involves the derivatization of a given sugar with hydrazine at pH 3 to form a hydrazone, which is reacted with fluorescamine following adjustment of pH to first 9.4 and then 7.4. The amount of sugar in a sample is quantitated by measuring the fluorescence intensity at an excitation wavelength of 400 nm and an emission wavelength of 490 nm. The assay is precise and reproducible, as indicated by intra- and inter-run variations of at most 3% and 4%, respectively. In addition to reducing sugars, the assay can also be used to measure aliphatic and aromatic aldehydes, but not acetone. Compared with an existing fluorometric sugar assay, the assay reported here does not require chromatographic separation of the fluorescent derivative from unreacted fluorescamine. The assay can, however, be potentially adapted for postcolumn detection of aldehydes, reducing sugars, and hydrazones in HPLC.

Acute effects of amiodarone on sodium currents in isolated neonatal ventricular myocytes: comparison with procainamide

Recent studies suggest that amiodarone's acute clinical effects in infants and children are related predominantly to its class I antiarrhythmic activity. However, the effects of amiodarone on Na+ currents have not been investigated directly in immature cardiac cells. Accordingly, the tight seal whole cell voltage clamp technique was used to measure time- and voltage-dependent Na+ currents in acutely isolated neonatal ventricular myocytes from 2- to 5-day-old rabbits, before and after addition of amiodarone (0.1-10 microM). To evaluate the class I antiarrhythmic activity of amiodarone in this age group, the effects of amiodarone on Na+ currents were compared with those of procainamide. Similar to procainamide, amiodarone significantly decreased peak inward Na+ current in neonatal ventricular myocytes. Moreover, both amiodarone and procainamide shifted the steady-state inactivation curve to more negative membrane potentials and delayed recovery of the Na+ current from inactivation. Thus, the effects of amiodarone on the Na+ current in immature myocardium are qualitatively similar to those of procainamide, suggesting that amiodarone may act acutely as a class I antiarrhythmic agent in the newborn heart.

Contributions of arginines-43 and -94 of human choriogonadotropin beta to receptor binding and activation as determined by oligonucleotide-based mutagenesis

Members of the glycoprotein hormone family contain a common alpha subunit and a hormone-specific beta subunit. Human choriogonadotropin (hCG) beta is a 145 amino acid residue protein glycosylated at 6 positions (2 N-linked and 4 O-linked oligosaccharides). In an effort to elucidate receptor determinants on hCG beta, we have used site-directed mutagenesis to prepare and express several mutant cDNAs with replacements at arginines-43 and -94. Arg-43 is invariant in all known mammalian CG/lutropin beta amino acid sequences, and Arg-94 is conserved in 10 of the 12 sequences. Moreover, various studies involving synthetic peptides and enzymatic digestions of intact beta chains suggest that these residues may be important in hCG receptor binding. Point mutants were made in which these two arginines were replaced with the corresponding residues in human follitropin beta, Leu-43 and Asp-94. The wild-type and mutant beta chains were expressed in CHO cells containing a stably integrated gene for bovine alpha, and heterodimer formation occurred. These heterologous gonadotropins were active in assays using transformed Leydig cells, competitive binding with standard 125I-hCG, and cAMP and progesterone production, but the potency was considerably less than that associated with the hCG beta wild-type-containing gonadotropin. The double-mutant protein Arg-43 to Leu/Arg-94 to Asp also associated with bovine alpha, but the resultant heterodimer exhibited only low activity. Replacement of each arginine with lysine yielded heterodimers that were at least as potent as bovine alpha-hCG beta wild type, but the Lys-43-containing beta chain appeared to exhibit a low degree of subunit association or reduced stability relative to the expressed hCG beta wild type. These results demonstrate that arginines-43 and -94 contribute to receptor binding through a positive charge.

Role of the invariant aspartic acid 99 of human choriogonadotropin beta in receptor binding and biological activity

The four human glycoprotein hormones are heterodimers that contain a common alpha subunit and a hormone-specific beta subunit. Within this hormone family, 23 amino acid sequences from 11 mammalian species are available. There are 19 invariant amino acid residues in the beta subunits, 12 of which are Cys that form six disulfide bonds. Of the remaining seven conserved amino acid residues, we have investigated the role of an Asp which occurs at position 99 in human choriogonadotropin beta (hCG beta). Site-directed mutagenesis was used to replace hCG beta Asp99 with three residues, Glu, Asn, and Arg, and to prepare an inversion double mutant protein, Arg94----Asp and Asp99----Arg. The cDNAs were placed in a eukaryotic expression vector, and the plasmids were transiently transfected into Chinese hamster ovary cells containing a stably integrated gene for bovine alpha. Radioimmunoassays demonstrated that the mutant forms of hCG beta were capable of subunit assembly to the same extent as hCG beta wild type. The heterologous heterodimers were assayed in vitro using transformed mouse Leydig cells (MA-10) by competitive inhibition of 125I-hCG binding and stimulation of progesterone production. The gonadotropins containing Glu and Asn were active, although the potency was less than that associated with the hCG beta wild type-containing gonadotropin. In contrast, the Arg99-containing mutant protein and the inversion mutant protein Asp94/Arg99 were devoid of activity. Thus, in hCG beta Asp99 can be substituted with certain residues without total loss of function, although replacement with a positively charged residue leads to an inactive heterodimer. The primary role of Asp99 in hCG beta seems to involve, either directly or indirectly, receptor recognition.

Isolation and sequencing of the Epstein-Barr virus BNLF-1 gene (LMP1) from a Chinese nasopharyngeal carcinoma

The BamHI fragment containing the Epstein-Barr virus (EBV) LMP1 gene was cloned from a genomic library of the nude mouse-propagated Chinese nasopharyngeal carcinoma CAO. The sequence of the LMP1 gene and its promoter and enhancer was determined. The nucleotide sequence of the CAO isolate differed from those of the B95-8 and Raji isolates in the promoter/enhancer region; the amino acid sequence of the protein also differed. Structural differences in the protein were located mainly in the 20 N-terminal residues and the array of repeated amino acids in the C-terminal part of the protein, in which the CAO isolate displays a cluster of seven perfect repeats of 11 amino acids (aa). Three of these repeats have no counterpart in the other virus strains. This, together with two deletions of five and 10 aa in the C-terminal part, yields a protein of 404 aa, compared to 386 aa for B95-8 and Raji. The larger LMP1 protein was detected on immunoblots of tissue samples from the CAO nude mouse tumour, and was also present in EBV-negative B cell lines and immortalized keratinocytes transfected with the cloned gene. A XhoI restriction site in exon 1 of the B95-8 BNLF-1 gene was absent from the CAO EBV isolate, as well as from 36 of 37 Chinese NPC biopsies tested. In contrast, 17 of 19 NPC biopsies of African origin retained this XhoI site.

[Determination of baicalin in xiaoer feire kechuan mixture by dual-wavelength spectrophotometry]

A method for the determination of baicalin in traditional Chinese medicine Xiaoer Feire Kechuan Mixture with dual-wavelength spectrophotometry is described. The interference of coexisting ingredients may be eliminated without separation of the samples. Both 751 and UV-3000 spectrophotometers were used.

Genetic diversity among toxigenic and nontoxigenic Vibrio cholerae O1 isolated from the Western Hemisphere

Multilocus enzyme electrophoresis was used to examine genetic relationships among and between toxigenic and non-toxigenic isolates of Vibrio cholerae O1 obtained from patients and the environment in the US Gulf Coast and surrounding areas. A total of 23 toxigenic and 23 non-toxigenic strains were examined. All the toxigenic and 7 of the non-toxigenic strains had the same alleles at 16 enzyme loci, whereas the balance of the nontoxigenic strains had 9 distinct combinations of alleles. This study suggests that all of the toxigenic strains belong to a single clone, and that while some of the non-toxigenic isolates were related, most were of diverse origin.

Calcium current measurements in acutely isolated neonatal cardiac myocytes

Action potentials and voltage clamp-induced ionic currents were recorded in acutely isolated neonatal rabbit cardiac myocytes using the whole-cell voltage clamp technique. Time- and voltage-dependent Ca2+ currents in neonatal myocytes were elicited by depolarizations from a holding potential of -80 mV to various clamp potentials. The maximal measured inward Ca2+ current was 206 +/- 10 pA (mean +/- SEM, n = 51). The peak current occurred at a mean membrane potential of 7.8 +/- 1.3 mV (n = 51). The Ca2+ current voltage relation was shifted 26 mV in the positive direction when the external Ca2+ concentration was increased 10-fold. Ca2+ current rundown was observed with a half-time of approximately 20 min. Cells dialyzed with solution containing the Ca2+ chelating agent, EGTA (0.04 mM), had action potential durations similar to those previously reported in papillary muscle. In contrast, a higher concentration of EGTA (14 mM) prolonged the action potential duration. Control of the cell internal ionic composition was achieved by dialysis of the cell with a time constant for Na+ ions of 1.2 to 2.6 min. Tetrodotoxin (10 microM), included in some experiments to block Ca2+ entry via Na+ channels, was shown to be more than 98% effective. These results characterize the whole-cell voltage clamp technique as applied to immature heart cells.

L- and T-type calcium channels in acutely isolated neonatal and adult cardiac myocytes

We have compared transsarcolemmal Ca2+ currents in acutely isolated neonatal (1- to 5-d-old) and adult rabbit cardiac myocytes prepared using similar enzymatic techniques. Time- and voltage-dependent inward Ca2+ currents were measured using the whole-cell voltage clamp technique. In neonatal myocytes, peak Ca2+ currents measured 114 +/- 10 pA (mean +/- SEM, n = 18) as compared with 2014 +/- 403 pA in adult myocytes (n = 5, p less than 0.001). Although adult myocytes had a larger surface area (estimated from cell capacitance) than neonatal cells (113 +/- 15 x 10(-6) versus 28 +/- 2 x 10(-6) cm2, p less than 0.001), the calculated peak current density was also significantly larger in adult cells (17.9 +/- 2.5 compared to 4.3 +/- 0.4 microA/cm2 for neonatal cells, p less than 0.001). The voltage dependence of the peak Ca2+ current was similar in neonatal and adult myocytes. Early transient (T-type) Ca2+ currents were also studied by comparing the current induced by depolarization to -20 mV from holding potentials of -40 and -80 mV. T-type Ca2+ channels were present in 91% of the adult cells but were evident in only 39% of the neonatal cells. In summary, voltage-gated Ca2+ current amplitude, current density, and T-type Ca2+ channel prevalence all increase with maturation. These data suggest that neonatal myocytes may be relatively deficient in Ca2+ channel activity when compared to adult myocytes.

Nonneoplastic enhancing lesions mimicking intracanalicular acoustic neuroma on gadolinium-enhanced MR images

The authors describe five patients with nonneoplastic lesions of the facial and/or vestibulocochlear nerves that demonstrated focal enhancement within the internal auditory canal on magnetic resonance (MR) images. MR and surgical findings for four patients with unilateral sensorineural hearing loss and one with Ramsay Hunt syndrome were reviewed. Three patients with hearing loss underwent surgical exploration and decompression of the internal auditory canal. The MR findings in all four patients with hearing loss were similar: Focal enhancement of the internal auditory canal was depicted on postcontrast T1-weighted images. Nonneoplastic lesions of the seventh and eighth cranial nerves may show focal enhancement on MR images, which mimics the appearance of a small intracanalicular neuroma. This potential for misdiagnosis may have important therapeutic implications.

Delineation via site-directed mutagenesis of the carboxyl-terminal region of human choriogonadotropin beta required for subunit assembly and biological activity

The choriogonadotropin beta subunit is unique in the human glycoprotein hormone family in containing a carboxyl-terminal extension, with four sites of O-glycosylation, that is not present in the other beta subunits. We have used site-directed mutagenesis to define boundaries on the extent to which truncations can be made at the COOH terminus without abolishing subunit assembly and biological activity. Two COOH-terminal deletion mutant chains of human choriogonadotropin beta, des(93-145) and des(101-145), were prepared and expressed in Chinese hamster ovary cells containing a stably integrated gene for bovine alpha. The heterologous gonadotropin, bovine alpha-human choriogonadotropin des(101-145) beta, formed a heterodimer and, when assayed with transformed murine Leydig cells in vitro, competed with the binding of standard human choriogonadotropin and stimulated both cAMP and progesterone production, albeit with a reduced potency relative to bovine alpha-human choriogonadotropin beta wild type. In contrast, human choriogonadotropin des(93-145) beta, expressed under identical conditions in the presence of bovine alpha, failed to form heterodimer and thus exhibited no competitive binding and was without effect on cAMP and progesterone levels. Consequently, removal of the putative determinant loop region of the beta subunit (residues 93-100), which is believed to be important in determining receptor specificity, abolishes association with alpha. Hence, in addition to its possible role as a receptor determinant, this region of the molecule appears to be critical for proper folding or subunit interaction. The truncated form of human choriogonadotropin beta lacking residues 101-145 is the shortest form of the subunit yet described that retains biological activity. Moreover, these results demonstrate that the proposed disulfide between Cys-26 and Cys-110 is not required for subunit assembly or for receptor binding and subsequent intracellular signaling.

Single-channel recording of inwardly rectifying potassium currents in developing myocardium

Properties of the inwardly rectifying K+ channel, which contributes to the maintenance of the resting membrane potential, were studied in neonatal rabbit ventricular myocytes using the patch-clamp technique. Inward rectification was evident in single-channel current-voltage (I-V) relations at potentials positive to the potassium equilibrium potential (Ek = 0 mV with [K+]o = [K+]i = 150 mM, [Mg2+]i = 2 mM). The single-channel conductance was 3.2 +/- 0.1 pS in physiological (5.4 mM) [K+]o. The zero-current potential shifted 48.4 +/- 2.4 mV for a ten-fold change in [K+]o in neonatal cells. External Ba2+ blocked the current in a dose-dependent manner. The voltage dependence, open-state probability and channel density of this channel were compared between neonatal and adult ventricular myocytes isolated by similar techniques. The open-state probability of the channel was approximately the same in neonatal (0.39 +/- 0.06, n = 13) as in adult cells (0.4 +/- 0.05, n = 11). However, in symmetrical transmembrane K+ concentration [( K+]o = [K+]i = 150 mM), the single channel conductance was significantly smaller in neonatal (25 +/- 0.3 pS, n = 25) as compared with adult cells (31 +/- 0.4 pS, n = 12). In addition, the relationship between resting membrane potential and [K+]o was measured in neonatal and adult myocytes. The resting membrane potential in the neonate was less dependent on [K+]o than in the adult. These results are consistent with an age-related change in resting membrane K+ permeability which may result from a developmental change in the single-channel conductance properties of the inwardly rectifying K+ channel.

Treatment of S antigen uveoretinitis with lipoxygenase and cyclo-oxygenase inhibitors

The role of metabolites of arachidonic acid (AA) in experimental autoimmune uveoretinitis was studied using inhibitors of AA metabolism. Nordihydroguaiaretic acid (NDGA), which inhibits predominantly the lipoxygenase (LO) pathway, or indomethacin, a specific cyclo-oxygenase (CO) inhibitor, was administered to rats immunized with retinal S antigen. Levels of various AA metabolites were measured in the inflamed uvea, and the severity of intraocular inflammation was quantitated by morphometric analysis. Histopathologically, the uveoretinitis was significantly suppressed following treatment with NDGA, while indomethacin treatment resulted in augmentation of the disease (p less than 0.05). These results tend to indicate that the inhibition of the LO rather than the CO pathway may be more beneficial in the treatment of autoimmune uveitis.

The distribution of S-100 protein in articular cartilage from osteoarthritic joints

The distribution and localization of S-100 protein was compared with safranin-O staining and H and E morphology in relatively unaffected, degenerative, and osteophytic regions of human articular cartilage from 26 joints obtained at the time of total joint replacement for osteoarthritis. S-100 protein immunoreactivity in osteophyte cartilage was more intense than in unaffected regions and comparable to the staining intensity found in metaplastic cartilage tufts in degenerating cartilage. Immunoreactivity for S-100 protein appeared more prominent in the deep layers of osteophyte cartilage adjacent to areas of matrix calcification.

[The anchoring of newly synthesized adenovirus DNA to the nuclear matrix]

After adenovirus infected HeLa cells were pulse labeled and pulse-chase labeled with 3H-thymidine, the nuclear matrix and DNA remaining tightly bound to the matrix were obtained by sequential cell fractionation. Measuring the radioactivity of labeled DNA indicated that newly synthesized viral DNA specifically attach to the nuclear matrix and the amount of binding DNA is in direct proportion to the viral DNA replication activity: then the DNA gradually detach from the matrix and are involved in viral assembly. Electron microscopic autoradiography of the extracted cells showed the virion and viral DNA associated with the nuclear matrix, and thus further confirmed the anchoring of newly synthesized viral DNA to the nuclear matrix.

Receptor binding of epidermal growth factor in cultured human choriocarcinoma cell lines: effects of actinomycin-D and methotrexate

Binding of epidermal growth factor (EGF) to its receptor was evaluated in the four cultured choriocarcinoma cell lines BeWo, NaUCC-1, NaUCC-2, and NaUCC-3. Also, the effect of the anti-tumor drugs actinomycin-D (Act-D) and methotrexate (MTX) on the EGF receptor binding was investigated in these cell lines. Incubation of these cells with [125I]EGF at 37 degrees C resulted in a higher binding than that at 22 degrees C or at 4 degrees C. These bindings were saturable during 30- to 60-min incubation, and were specific and reversible. Scatchard analysis showed that the maximal number of receptor binding sites was 2.89 X 10(3)/cell in BeWo cells, 2.04 X 10(3)/cell in NaUCC-1 cells, 1.84 X 10(3)/cell in NaUCC-2 cells, and 1.01 X 10(3)/cell in NaUCC-3 cells. Preincubation with Act-D or MTX for 24 hr decreased the number of receptor binding sites (26%-53%) and slightly increased the receptor binding affinities. Combination of the two drugs resulted in a further diminution of EGF receptor binding sites in BeWo, NaUCC-1, and NaUCC-3 cells, respectively, but reversed the Act-D effect in NaUCC-2 cells. These results indicated that choriocarcinoma tissue is rich in EGF receptors, that the anti-tumor drugs Act-D and MTX diminish the receptor binding sites in the tissue, and suggest that MTX might induce a drug resistance to Act-D in some choriocarcinoma tissue.

[Rupture of splanchnic artery aneurysms (a report of 19 cases)]

During the past 30 years, 19 patients were admitted in our hospital with acute rupture of splanchnic artery aneurysms. There were 12 hepatic artery, 5 gastroduodenal-pancreaticoduodenal and 2 superior mesenteric artery aneurysms. The aneurysms ruptured into the biliary tract in 13 patients, and 3 into the abdominal cavity, and 3 into the upper gastrointestinal tract. Twelve aneurysms resulted from choledochitis or pancreatitis, 5 from atherosclerosis and 2 from trauma. It is difficult to make a correct diagnosis preoperatively. The most valuable examination is selective angiography of the celiac and superior mesenteric arteries. Nine of our patients were correctly diagnosed preoperatively by arteriography. Thirteen patients were treated by surgery and 7 died. Prognosis depended on anatomic relations of the aneurysms and the primary underlying disease.

Möbius and Möbius-like syndromes (TTV-OFM, OMLH)

There exists a spectrum of syndromes characterized by cranial nerve palsies, limb anomalies, and craniofacial malformations. Criteria based on type and severity of limb anomaly or presence or absence of cranial nerve palsy may alter the syndrome nomenclature due to a selection bias but do not appear to benefit syndrome delineation to any extent. Patients with seventh nerve palsy and abduction weakness are usually diagnosed as having Möbius syndrome by ophthalmologists. The observed ocular motility findings range from primarily abduction deficiencies to patients who have a Duane or gaze palsy pattern of horizontal movements. Some cases previously described as "sixth nerve and partial third" may better fall into one of the latter groups, since an isolated adduction deficit as a manifestation of third nerve involvement is rare. The presence of clinical appearance of Duane syndrome in these Möbius-type patients raises the possibility of abnormal innervation of the lateral rectus as an explanation of some patterns of motility observed.

Association of adenovirus DNA transcribed activity with nuclear matrix of host cells

With gentle cell extraction techniques, various DNA components in the HeLa cells after 6 h of adenovirus infection have been obtained. Adenovirus, early transcribed regions (E2a, E1b) and a late transcribed region (L2) were used as probes in Southern hybridization, respectively. The experiment showed that only actively transcribed adenovirus DNA fragments would tightly bind to the nuclear matrix of host cells. We inferred that the nuclear matrix of host cells plays an important role in viral DNA transcription.

The effect of thiamine deficiency on the structure and physiology of the rat forebrain

Dietary thiamine deficiency, enhanced by pyrithiamine administration in adult rats, produces overt lesions in the brain that are especially prominent in the thalamus. The present study was undertaken to determine whether the thalamic lesions could be correlated with alterations in the physiological properties of neurons in the thalamus and somatosensory cortex. The regimen for experimentally inducing thiamine deficiency produced large lesions in the thalamus of every case; the lesions included most, if not all, of the neurons in the intralaminar thalamic nuclei. The extent of the lesion in the intralaminar thalamus was highly correlated with the loss of bilaterally synchronous spontaneous activity in the cerebral cortex. This correlation was seen in animals analyzed as early as 1-18 hr after the appearance of opisthotonus, the crisis state of thiamine deficiency, and as late as 2-9 weeks of recovery following thiamine replacement therapy. The loss of bilateral synchronous bursting neuronal activity following intralaminar thalamic lesions is consistent with the proposed role of the intralaminar thalamus as a pacemaker for rhythmic cortical activity (Armstrong-James et al., Exp. Brain Res., 1985; Fox and Armstrong-James, Exp. Brain Res. 63: 505-518, 1986). The location and size of the central lesions within the thalamus suggest that the observed neuronal loss could result from a nonhemorrhagic infarction in the ventromedial branches of the superior cerebellar arteries. Experimental thiamine deficiency also produced alterations in the receptive field properties of the somatosensory cortex neurons in all animals examined. Changes in cortical receptive field properties were correlated with the destruction of sensory relay neurons in the thalamic ventrobasal complex. The loss of the central lateral thalamic input to the cortex and the loss of somatosensory relay neurons in the ventrobasal thalamus in experimental thiamine deficiency produce alterations in cortical function which may contribute to deficits in memory and cognition analogous to those which characterize Korsakoff's psychosis in humans.

Dissociation of hCG-receptor complex and detection of hCG receptors in human chorionic tissues

We developed a radioreceptor assay (RRA) system for investigating occupied hCG receptors by using a rat testis membrane fraction. Treatment with dithiothreitol, neuraminidase, and low pH (3.3) buffer partially dissociated hCG from its receptor with dissociation rates of 42.8%, 35.2%, and 68.7%, respectively. Specific receptor rebinding was unaffected and showed competitive inhibition of [125I]hCG rebinding by unlabeled hCG. Scatchard plot analysis yielded a rebinding Km of 1.798-3.496/pM. High concentrations of NaCl and MgCl2 had no obvious effect on the [125I]hCG-receptor complex. Triton X-100 and high concentration MnCl2 treatments resulted in the loss of the receptor rebinding activity. We also investigated human chorionic tissue (at 8 weeks, 11 weeks, 16 weeks, 24 weeks, and term) for hCG receptors using the above method. Treatments with different agents increased [125I]hCG binding in this tissue preparation 139-226%, but Scatchard analysis failed to demonstrate any specificity. [125I]hCG uptake by the choriocarcinoma BeWo cell-line increased 151-193% after similar treatments, but this increase could not be competitively inhibited by unlabeled hCG. Treatment with dithiothreitol, neuraminidase, and low pH (3.3) buffer seems feasible for detecting hCG-occupied receptors. Our results suggest that there are no hCG receptors distributed on the surface of the syncytiotrophoblast of human placenta.

Inherited snowflake cataracts

The authors report two unusual pedigrees of flake-like cataracts inherited as an isolated mendelian trait, presumably autosomal dominant. The most striking biomicroscopic feature is an accumulation of large white irregular flakes ('type B opacities') scattered throughout the equatorial cortex, with apparently less involvement of the nucleus. Some of these opacities are globular, but most are flattened and have feathery edges. These type B opacities are clinically and microscopically identical in the two families. Type B lesions are characterized histologically by irregular pale-staining areas. Ultrastructurally, these areas show large collections of microglobular degeneration immediately adjacent to normal-appearing lens fibers. Electron probe studies demonstrate normal calcium levels. 'Type A' opacities are biomicroscopically smaller, punctate, and clinically non-specific. Ultrastructurally, type A opacities include clusters of medium sized lenticular globules, each of which is larger than the individual microglobular abnormalities of type B lesions, although the aggregated type B lesion is considerably larger than an individual type A lesion. The microscopic appearance of this inherited cataract appears to be unique.