[Changes in blood oxytocin levels in cases of pregnancy induced hypertension]

Serial measurements of plasma oxytocin concentration were done by radioimmunoassay in 38 cases of pregnancy induced hypertension (PIH) and 38 cases of normal pregnancy (NP). The results showed that there was no obvious difference in the plasma oxytocin concentration between patients with early PIH and NP, but a higher concentration in cases with PIH at term pregnancy than that in NP and a significantly higher level in intrapartum women with PIH. The results also indicated a much higher oxytocin concentration in cases of moderate and severe PIH as compared to that of NP. An obviously higher level of plasma oxytocin was found in severe PIH than in mild PIH. Based on this study we suggest that the clinical use of oxytocin in cases with PIH should be different from that in NP.

Human norepinephrine transporter. Biosynthetic studies using a site-directed polyclonal antibody

Antibodies have been raised against synthetic peptides derived from the predicted primary sequence of the human cocaine- and antidepressant-sensitive norepinephrine (NE) transporter (NET). One antibody (N430), raised and purified against a putative intracellular human norepinephrine transporter (hNET) epitope, detects hNET expression in a stably transfected cell line (LLC-NET) by indirect immunofluorescence only in the presence of detergent, while no immunoreactivity is observed in either the parental cells (LLC-PK1) or in LLC-NET cells incubated with preimmune sera or peptide absorbed antibody. N430 immunoblots of LLC-NET cell extracts reveal two major immunoreactive hNET species in these cells, migrating at 80 and 54 kDa, respectively. Pulse-chase N430 immunoprecipitation studies confirm that the 54-kDa species is a transient, glycosylated intermediate of a longer lived, more highly glycosylated protein with an apparent M(r) of 80,000. In contrast, a 54-kDa species is the primary hNET product in vaccinia virus T7-infected HeLa cells, transiently transfected with hNET cDNA. PNGase F digestion of extracts prepared from LLC-NET- and hNET-transfected HeLa cells convert all immunoreactive species to a 46-kDa form, equivalent to that observed following incubation of whole cells with the glycosylation inhibitor tunicamycin. As transiently transfected HeLa and stable LLC-NET cells exhibit a pharmacologically similar NE transport activity, it appears likely that the additional glycosylation evident in the stable line does not contribute significantly to antagonist sensitivity. On the other hand, NE transport and antagonist ([125I]RTI-55) binding assays on whole LLC-NET cells treated with tunicamycin reveal a pronounced reduction in NE transport activity and hNET membrane density paralleled by an inability of NET proteins to replenish the higher M(r) hNET pool. These findings suggest an obligate role for N-linked glycosylation in hNET biosynthetic maturation, stability, and functional expression. In summary, N430 antibody is a useful tool for the visualization and characterization of hNET gene products and has permitted the first direct evaluation of biosynthetic steps leading to functional catecholamine transporter expression.

Gene targeting and its application to the study of B-cell development

The use of gene targeting technology for the study of gene functions in vivo continues to expand. The application of this technology as well as further improvements in the technology itself enable us to examine the influence of various genetic elements and gene products on B-lymphocyte development and function.

Stable expression of biogenic amine transporters reveals differences in inhibitor sensitivity, kinetics, and ion dependence

We have constructed stable cell lines expressing transporters for dopamine (DA), norepinephrine (NE), and serotonin (5-HT) by transfection with cloned cDNAs. The parental LLC-PK1 cell does not express any of these neurotransmitter transporters. Therefore, monoamine transport activities in each of these cell lines are due to the transfected DNA only, allowing comparison in the same background. Drug inhibition profiles for each cell line are distinct and as expected for each transporter. LLC-NET and LLC-DAT cells transported both NE and DA and both cell types exhibited a lower KM for DA transport than for NE transport. Analysis of Vmax data for LLC-NET cells suggests that substrate is bound to the NE transporter during the rate-limiting step(s) in transport. The cocaine analog 2-beta-carbomethoxy-3 beta-(4-[125I]iodophenyl)tropane binds to each cell type, and is displaced by transport substrate in each case. Binding and transport measurements on parallel cell cultures allowed estimation of turnover numbers for norepinephrine, dopamine, and serotonin transporters. All three transporters require external Na+ and Cl-. The Na+ concentration dependence suggests that a single Na+ ion is involved in transport catalyzed by norepinephrine and serotonin transporters while more than one Na+ ion participate in transport mediated by the dopamine transporter.

Generation of a mouse strain that produces immunoglobulin kappa chains with human constant regions

Humanized antibodies are highly efficient as immunotherapeutic reagents and have many advantages over rodent antibodies. A mouse strain was generated by gene targeting to replace the mouse kappa light chain constant (C) region gene with the human C kappa gene. Mice homozygous for the replacement mutation (C kappa R) produced normal concentrations of serum antibodies, most of which carry chimeric kappa light chains, and mounted normal immune responses to hapten-protein conjugates. This technology provides a feasible option for the generation of high-affinity humanized antibodies by means of the powerful somatic hypermutation-selection mechanism.

(+)Naloxone potentiates the inotropic effect of epinephrine in the isolated dog heart

Naloxone potentiates the inotropic effect of circulating catecholamines in the isolated canine heart. The stereospecificity of this response was evaluated with the aid of the less active (+)enantiomer of naloxone. The more common (-)isomer of naloxone increased the contractile response to epinephrine only at the higher dose tested (4 mg). This effect of naloxone was not observed at a tenfold lower dose (0.4 mg), indicating a very narrow dose-response range. (+)Naloxone was effective at the lower dose and was, therefore, equal to or better than (-)naloxone in potentiating the inotropic effect of epinephrine. When introduced afterward, (-)naloxone did not add to the effect of (+)naloxone. These data suggest that naloxone modifies cellular responsiveness to catecholamines through a nontraditional opiate receptor, through a nonopiate receptor, or through a nonreceptor mechanism.

Independent control of immunoglobulin switch recombination at individual switch regions evidenced through Cre-loxP-mediated gene targeting

We have employed a method based on the Cre-loxP recombination system of bacteriophage P1 to generate a mouse strain in which the JH segments and the intron enhancer in the IgH locus are deleted. By analysis of immunoglobulin isotype switch recombination in heterozygous mutant B cells activated by lipopolysaccharide plus interleukin-4, we show that, on the mutant chromosome, switch recombination at the mu gene switch region is strongly suppressed, whereas the switch region of the gamma 1 gene is efficiently rearranged. These data demonstrate an independent control of switch recombination at individual switch regions and suggest that, in the process of switch recombination, the alignment of the recombining strands occurs independently of and probably after the introduction of double-strand breaks into the switch regions involved.

Mechanisms of oxygen-induced contraction of ductus arteriosus isolated from the fetal rabbit

The present study was designed to investigate the effect of O2 on intracellular Ca concentration ([Ca]i) in the ductus arteriosus and the mechanisms for O2-induced ductal contraction. The force of isometric contraction of the ring of the ductus arteriosus isolated from fetal rabbits at 30 days of gestation (term, 31 days) was measured. The ductus arteriosus was loaded with fura 2, a calcium-sensitive dye, and [Ca]i was determined from the ratio of fluorescence intensity at 340 and 380 nm excitation wavelengths. The ductus arteriosus was initially superfused with hypoxic control solutions and contraction was induced by application of oxygenated solutions. The O2-induced contraction of the ductus arteriosus was associated with increases in [Ca]i and was eliminated in the absence of extracellular calcium. An increase in [K]o from 5 to 50 mM, which causes membrane depolarization, induced ductal contraction. The calcium channel blockers verapamil, diltiazem, and nickel caused a similar inhibition of O2-induced contraction as well as KCl-induced contraction. The role of intracellular calcium stores in O2-induced ductal contraction was examined using ryanodine, an inhibitor of calcium uptake and release from the sarcoplasmic reticulum. The inhibition of O2-induced contraction by ryanodine was minimal. Infusion of glibenclamide, an inhibitor for opening the ATP-sensitive potassium channel, caused contraction of the ductus arteriosus in the hypoxic solution. Cromakalim, an opener of ATP-sensitive potassium channels, completely relaxed the contraction induced by O2. These data suggest that O2 increases [Ca]i and causes contraction in the ductus arteriosus. Application of O2 may change from anaerobic to aerobic metabolism and depolarize membrane potential by closing the ATP-sensitive potassium channel, which in turn increases calcium influx via the voltage-dependent calcium channel. Mechanisms other than the ATP-sensitive potassium channel may also be involved in the O2-induced contraction and remain to be studied.

Anti-inflammatory oleanane triterpenes from Tripterygium wilfordii cell suspension cultures by fungal elicitation

Treatment of cell suspension cultures of Tripterygium wilfordii with an autoclaved Botrytis sp. homogenate rapidly increased the synthesis of a family of oleanane and friedelane triterpenes, including the antiinflammatory oleanane triterpene 3β,22α-dihydroxyolean-12-en-29-oic acid. This compound exceeded 30 mg · l(-1) in 13 day elicitations with 12 l bioreactors, in contrast to control levels of less than 5 mg · l(-1). Cell cultures treated with the fungal elicitor provided higher triterpene yields in less time than cultures in a diterpene production medium or whole plants. Elicited production has been developed for commercial application in light of the successful treatment of rheumatoid arthritis with Tripterygium extracts.

Immunoglobulin heavy and light chain genes rearrange independently at early stages of B cell development

The compartment of mouse B cell progenitors can be resolved into five developmentally related fractions by multicolor flow cytometry. Using this system and employing mutant mice in which the membrane exon of the mu chain, the lambda 5 gene, or the JH locus was inactivated by gene targeting, we found that expression of the pre-B cell receptor complex is necessary for the transition from the large CD43+ to the small CD43- pre-B cell stage. We report the occurrence of immunoglobulin heavy and light chain gene rearrangement at the stage of large B cell precursors. We show that neither the pre-B cell receptor complex nor any gene rearrangement in the heavy chain locus is required for the induction of kappa light chain gene rearrangement in early B cell progenitors.

HCO3(-)-dependent intracellular pH regulation in the premature myocardium

This study investigated developmental changes in Na(+)-H+ exchange and HCO3(-)-Cl- exchange activities in newborn and adult rabbit hearts. pHi was measured using the fluorescent dye 2',7'-bis(2-carboxyethyl)-5(6)-carboxyfluorescein in isolated myocytes. Myocardial mechanical function was measured in the isolated ventricular preparation. Intracellular acidosis with normal pHo was induced by an NH4Cl (10 mM) prepulse technique. Upon removal of NH4Cl, pHi fell transiently and then recovered toward the control level. In the HCO3-/CO2-buffered solution, the rate of recovery of pHi in the newborn was greater than in the adult. In the HCO3-/CO2-buffered solution, 5-(N-ethyl-N-isopropyl)amiloride (EIPA), an inhibitor of Na(+)-H+ exchange, inhibited the recovery of pHi completely in the adult. In the newborn, however, significant recovery of pHi was observed in the presence of EIPA. In the presence of both EIPA and 4-acetamido-4'-isothiocyanatostilbene-2',2'-disulfonic acid (SITS), an inhibitor of HCO3(-)-Cl- exchange, the recovery of pHi was not observed in the two age groups. In the HEPES-buffered solution that did not contain HCO3-/CO2, the rate of recovery of pHi after NH4Cl removal was similar in the two age groups. In the HEPES-buffered solution, the recovery of pHi was completely inhibited by EIPA in the two age groups. In the presence of EIPA in the HCO3-/CO2-buffered solution, contractile function decreased during acidosis after NH4Cl removal and did not recover in the adult. In the newborn, significant recovery of contractile function was observed after NH4Cl removal in the presence of EIPA. The recovery of mechanical function observed in the presence of EIPA in the newborn was inhibited by SITS. These data suggest that, although there is no developmental change in the Na(+)-H+ exchange activity, HCO3(-)-Cl- exchange is more active in the premature myocardium. The presence of the HCO3(-)-Cl- exchanger is important in maintaining myocardial contractile function during acidosis, especially when Na(+)-H+ exchange is inhibited and may partly explain the greater resistance of the premature myocardium to acidosis.

Norepinephrine stimulates the direct breakdown of phosphatidyl inositol in rat tail artery

When segments of rat tail artery were labeled with [3H]inositol and then stimulated with norepinephrine (NE), the inositol phosphates produced were primarily IP and IP2, together with a small but significant amount of Ins(1,4,5)P3 and a very small amount of Ins(1,3,4,5)P4. It has been unclear in many studies whether or not the relatively large levels of IP and IP2 produced in [3H]inositol-labeled tissue represent indirect products of phosphatidyl inositol(4,5)bis phosphate breakdown (through Ins(1,4,5)P3) or direct products of phosphatidyl inositol 4 monophosphate and phosphatidyl inositol breakdown. In order to answer this question tail artery segments were prelabeled with [3H]inositol and then permeabilized with beta escin and stimulated with norepinephrine and GTP gamma S, so that increases in IP, IP2, and Ins(1,4,5)P3 were still observed. If these permeable segments were stimulated with agonist in the presence of compounds known to inhibit Ins(1,4,5)P3 5-phosphatase, such as glucose 6P, (2,3)diphosphoglycerate, or Ins(1,4,5)P3, the levels of labeled Ins(1,4,5)P3 and labeled IP2 were increased, while the level of stimulated labeled IP was unchanged. This indicated that some of the IP2 and IP formed in these cells was produced from PIP2 but that some of these compounds might be formed from PIP or PI. When the isomers of inositol monophosphate, Ins 1P and Ins 4P, were separated by HPLC, it was shown that after prelabeled tail artery was stimulated by norepinephrine for periods of 1-2 min, the predominant isomer formed was Ins 4P, indicating either PIP2 or PIP as the source. However, after 5-20 min stimulation, both Ins 1P and Ins 4P were formed in equal amounts, suggesting that during sustained stimulation of smooth muscle PI itself was broken down directly. Therefore it appears that within 1-2 min of norepinephrine addition to vascular smooth muscle the bulk of the IP and IP2 produced are derived from PIP2 via IP3, while after 20 min of norepinephrine treatment much of the IP comes directly from PI. This suggests that the regulation of PLC in this tissue is more complicated than has been previously believed.

Dynorphin, naloxone, and overflow of norepinephrine during cardiac nerve stimulation in dogs

The effects of dynorphin-(1-9) and naloxone on norepinephrine (NE) overflow and myocardial contractility were determined during left cardiac nerve stimulation in the anesthetized dog. Stimulation-induced increases in NE overflow from the left ventricle were monitored during control conditions, during infusion of dynorphin-(1-9), during dynorphin plus naloxone, and after naloxone alone. Four electrical stimulations were applied for 1 min at 20-min intervals. Repeated left cardiac nerve stimulations (control group) reduced stimulated NE overflow 50-60% by 1 h. If stimulations were only conducted at 0 and 1 h, the decline in NE overflow was not observed. Intracoronary dynorphin (2 nmol.min-1.kg-1, 20 min) lowered the stimulation-induced increase in NE overflow further and reduced first time derivative of left ventricular pressure (dP/dt) and myocardial O2 consumption responses. Naloxone (100 micrograms/kg) prevented all of the dynorphin-mediated effects. When given alone, naloxone increased both NE overflow and left ventricular dP/dt during stimulation and prevented or significantly delayed the gradual decline in overflow observed in stimulated controls. A postjunctional effect of dynorphin was evaluated by comparing contractile responses to the intracoronary infusion of NE before and during dynorphin. Dynorphin did not alter contractile function at rest or during NE infusion. In summary, dynorphin-(1-9) depresses nerve stimulation-induced, cardiac NE overflow, and myocardial contractility in a naloxone-reversible fashion. Alone, naloxone appears to regulate stimulated NE overflow through a qualitatively different mechanism. Endogenous opioids may normally moderate myocardial function during cardiac nerve stimulation by regulating junctional NE concentrations through a combination of effects on NE release and/or its subsequent reuptake.

Norepinephrine-induced phosphatidylcholine hydrolysis by phospholipases D and C in rat tail artery

Rat tail arterial segments were incubated with [3H]choline to selectively label endogenous phosphatidylcholine. Norepinephrine (NE; 10(-5) M) addition for periods of 10 s to 30 min significantly increased the concentration of extracellular phosphatidylcholine metabolites, [3H]choline, and [3H]phosphocholine. The release of [3H]choline and [3H]phosphocholine from the segments was NE dose dependent (10(-6)-10(-3) M). NE also increased the formation of [3H]phosphatidylethanol in [3H]myristate-labeled tail artery in the presence of ethanol, characteristic of phospholipase D activity. NE-induced phosphatidylcholine hydrolysis was blocked by pretreatment with prazosin (10(-5) M) and was unchanged by pretreatment with propranolol (10(-5) M). 4 beta-phorbol 12,13-dibutyrate (PDBu, 10(-6) M) stimulated the release of [3H]choline, which was inhibited by pretreatment with staurosporine (10(-5) M). The stimulatory effect of NE on phosphatidylcholine metabolism was not altered by either pretreatment with staurosporine (10(-5) M) or calcium-free buffer. In summary, we have demonstrated NE-stimulated phosphatidylcholine hydrolysis by phospholipase D and C in intact vascular smooth muscle. This effect of NE was dose dependent and was mediated through the alpha 1-adrenergic receptor. Norepinephrine and PDBu stimulated phosphatidylcholine hydrolysis through different mechanism(s), and the stimulatory effect of NE did not seem to require protein kinase C and calcium influx.

Domains of type X collagen: alteration of cartilage matrix by fibril association and proteoglycan accumulation

During endochondral bone formation, hypertrophic cartilage is replaced by bone or by a marrow cavity. The matrix of hypertrophic cartilage contains at least one tissue-specific component, type X collagen. Structurally type X collagen contains both a collagenous domain and a COOH-terminal non-collagenous one. However, the function(s) of this molecule have remained largely speculative. To examine the behavior and functions of type X collagen within hypertrophic cartilage, we (Chen, Q., E. Gibney, J. M. Fitch, C. Linsenmayer, T. M. Schmid, and T. F. Linsenmayer. 1990. Proc. Natl. Acad. Sci. USA. 87:8046-8050) recently devised an in vitro system in which exogenous type X collagen rapidly (15 min to several hours) moves into non-hypertrophic cartilage. There the molecule becomes associated with preexisting cartilage collagen fibrils. In the present investigation, we find that the isolated collagenous domain of type X collagen is sufficient for its association with fibrils. Furthermore, when non-hypertrophic cartilage is incubated for a longer time (overnight) with "intact" type X collagen, the molecule is found both in the matrix and inside of the chondrocytes. The properties of the matrix of such type X collagen-infiltrated cartilage become altered. Such changes include: (a) antigenic masking of type X collagen by proteoglycans; (b) loss of the permissiveness for further infiltration by type X collagen; and (c) enhanced accumulation of proteoglycans. Some of these changes are dependent on the presence of the COOH-terminal non-collagenous domain of the molecule. In fact, the isolated collagenous domain of type X collagen appears to exert an opposite effect on proteoglycan accumulation, producing a net decrease in their accumulation, particularly of the light form(s) of proteoglycans. Certain of these matrix alterations are similar to ones that have been observed to occur in vivo. This suggests that within hypertrophic cartilage type X collagen has regulatory as well as structural functions, and that these functions are achieved specifically by its two different domains.

Dialyzed fetal bovine serum increases cytogenetic fragile X expression

Short-term whole blood cultures from 9 unrelated male individuals with the fragile X [fra(X)] syndrome were exposed to 5-fluorodeoxyuridine (FUdR). The fra(X) frequency was higher in 8 of 9 cases where the complete medium contained dialyzed fetal bovine serum (DFBS). In 3 of the cases, the fra(X) frequency nearly tripled (e.g., 12/100 to 33/100) while in 2 others, it nearly doubled (e.g., 15/100 to 29/100). When DFBS cultures from 2 other fra(X) individuals were exposed to increasing folic acid concentrations ranging from 2 to 4,000 x 10(-6) M, there was virtually no change in fra(X) expression. In 6 of 9 DFBS cultures, the mitotic index decreased, and it increased in 3. Therefore, although the fra(X) frequency increased, in most DFBS cultures the mitotic index decreased. Whether the reduction in mitotic index indicates an inverse correlation between reduced mitotic index and increased fra(X) expression, at least in cultures from some individuals, will be determined by additional studies.

IN CONCLUSION

(1) medium supplementation with dialyzed fetal bovine serum should be considered when using FUdR for fra(X) identification in order to avoid potentially false negative results; (2) there appears to be no direct correlation between increased mitotic index and increased fra(X) expression in whole blood cultures; (3) increased folic acid concentrations do not affect fra(X) expression when FUdR fra(X) induction is employed; therefore requesting people to refrain from taking vitamins, including folic acid, before fra(X) testing (a practice that still persists in some places) appears unnecessary.

Fra(X)(q27.2), the common fragile site, observed in only one of 760 cases studied for the fragile X syndrome

Cell cultures from 760 whole blood, amniotic fluid, chorionic villus sample, and peripheral umbilical blood sample specimens were exposed to multiple fra(X)(q27.3) induction systems (none had aphidicolin). Fifty-three exhibited the rare fragile site, fra(X)(q27.3) or FRAXA, none of which demonstrated the common fragile site or FRAXD at band Xq27.2. Only one cell in one of the negative whole blood FUdR-treated cultures from a mentally retarded male showed FRAXD. Therefore, it appears that FRAXD occurs very rarely in cultures treated to induce FRAXA since only one positive cell was observed in over 88,000 analyzed. It appears that very low frequencies of fra(X)(q27) can be accounted for only in part by the presence of the common fragile site since only one of 9 cases, each with one fra(X)(q27) positive cell, exhibited FRAXD and the others were FRAXA. After confirmation of FRAXA with direct DNA testing in a large number of low frequency cases, it should be possible to rely on the detection of very low frequencies of fra(X)(q27.3), e.g., 1% with at least 2 positive cells.

Recovery of DNA from agarose gels using a modified Elutrap

We have made a significant improvement in the electroelution device, Elutrap (Schleicher and Schuell) by substituting an agarose gel barrier, which is made from 0.6% agarose (SeaKem GTG; FMC Corporation), into the elution chamber in place of the manufacturer specified BT2 membrane. This modification substantially increases the DNA recovery from agarose gels, even in samples containing less than 1 microgram of DNA, and shortens elution times particularly for large sizes of DNA (greater than 4.4 kbp). Additionally, the gel barrier provides a reproducible quantity and quality of DNA recovery. The high quality of the eluted DNA using the modified Elutrap makes this system suitable for further DNA manipulations.

Screening for opioids in dog heart

Dog hearts divided into right and left atria, right and left ventricles and intraventricular septum were homogenized in acid for extraction. Total opioids, and specific peptides (methionine-enkephalin, methionine-enkephalin-arg6-gly7-leu8) were determined by radioreceptor and radioimmunoassay, respectively. Catecholamines were quantitated amperometrically following HPLC. The effects of anesthetic agents (pentobarbital, alpha-chloralose), hemorrhage and ganglionic blockade (hexamethonium and atropine) were evaluated. Total opioids, enkephalins and epinephrine were distributed uniformly throughout the myocardium, while norepinephrine was preferentially concentrated in the atria. Immunoreactive methionine-enkephalin accounted for only 1 to 2% of the total cardiac opioids estimated by radioreceptor assay. Hemorrhage lowered methionine-enkephalin content throughout the myocardium with no significant effect on total opioids or catecholamines. Ganglionic blockade increased total opioid, methionine-enkephalin-arg6-gly7-leu8 and catecholamine content without altering methionine-enkephalin content. HPLC of left ventricular extracts demonstrated that 50% of met-enkephalin-immunoreactivity eluted at retention times equal to synthetic metenkephalin. In summary, there appears to be substantive opioid concentrations within canine myocardium which respond to physiological and pharmacological interventions. These cardiac opioid responses do not parallel changes observed for catecholamines under the same conditions.

Influence of Larval Rearing Conditions on the Body Size and Flight Capacity of Epiphyas-Postvittana Moths

Effects of rearing conditions of larvae on the body weight and flight duration of the light brown apple moth, Epiphyas postvittana (Walker), were evaluated in the laboratory. The body weight of both male and female moths at emergence decreased with increasing temperature from 15 to 28-degrees-C during larval stages; in contrast, flight duration increased with rising temperature. There was no effect of larval density on flight duration, although the body weight of moths decreased as density increased. Variation in water content of artificial diet showed a significant influence on flight duration of female moths, but not on body weight in either sex. Flight duration was different only for females when their larvae were reared on young leaves of four host plants. Female moths from larvae on Rumex crispus and Plantago lanceolata flew for significantly longer periods than those from larvae on Trifolium repens and Pyrus malus. Larvae fed on young leaves yielded adults that flew for longer periods than those fed on senescent leaves. Inconsistency in relationships between body weight and flight duration of moths with respect to influences of different environmental factors during the larval stages indicates that flight capacity is unlikely to be influenced by body size in this species.