Experimental study on the model of coronary artery thrombosis in dog

We have developed a model of coronary artery thrombosis in dog by using the method stimulating coronary adventitia with direct current. The results have shown that the thrombi are similar to human artery thrombi in composition and the model of coronary artery thrombosis is satisfactory and the time of forming thrombosis is shorter than that by other methods.

[Some biochemical indexes in white rabbit's blood affected by acute high intensity microwave]

Irradiation of white rabbits by 10, 50, 100 and 200 mW/cm2 microwave respectively can cause the disorder of protein metabolism, the abnormality of blood sugar, and the change of the activity of serum alpha-hydroxybutyrate dehydrogenase, lactate dehydrogenase, glutamic oxalacetic transaminase, glutamic pyruvic transaminase, acid phosphatase ect. These changes can be used as indexes in the evaluation of the effect of acute high intensity microwave exposure. The effect on the organism mainly depends on the intensity of exposure provided the dose of microwave remains the same.

[The effect of sodium prasterone sulfate on lactation]

To study the relationship between sodium prasterone sulfate and lactation, blood samples were collected from 120 cases. Sixty cases were in study group (at different periods: during the 3rd trimester, and 1st, 3rd day postpartum) including 30 cases using 100mg sodium prasterone sulfate, 30 cases (using 200mg sodium prasterone sulfate), 60 cases were in control group. The serum levels of estradiol (E2), prolactin (PRL) and plasma levels of oxytocin (OT) were measured by radioimmunoassay, and the production of breast milk was observed. The results showed no statistically significant difference of serum E2, PRL and plasma OT between (sodium prasterone sulfate) study groups and control groups, and the production of breast milk indicated also no significant difference between the 2 groups. The conclusion is that low-dose sodium prasterone sulfate (200mg/day, 600mg/week) did not affect the production of breast milk.

Transcriptional repression of fibronectin gene expression in v-src transformation

V-src-dependent and -independent alterations in the steady-state content, rates of synthesis, and turnover of fibronectin protein and mRNA were identified using rat fibroblasts which are temperature sensitive for p60v-src activity. Activation of p60v-src caused a fivefold reduction in the rate of fibronectin biosynthesis. The v-src-dependent decrease in fibronectin biosynthesis resulted from a similar reduction in the steady-state content of fibronectin mRNA. This change was reversible and required more than 24 h, implying an indirect effect of p60v-src on fibronectin gene expression. The rate of fibronectin mRNA turnover and pattern of alternative splicing were unchanged following p60v-src activation, indicating that these regulatory steps are insensitive to v-src transformation. A v-src-specific reduction of at least threefold was measured for the rate of fibronectin gene transcription, and gene transfer studies using fibronectin promoter-CAT reporter genes indicated that transcriptional repression occurs at the level of initiation. When p60v-src was inactive, CAT reporter genes controlled by 4.9 or 3.2 kb of the rat fibronectin promoter exhibited relatively increased CAT activity (approximately twofold) compared to another CAT reporter construction controlled by only 880 bp of the fibronectin promoter. In contrast, CAT activity was relatively reduced (approximately twofold) for the reporter constructions containing 4.9 or 3.2 kb of the promoter when p60v-src was active. These findings indicate that the distal portion of the fibronectin promoter contains a v-src-sensitive element(s) which mediates a decrease in the rate of fibronectin transcription initiation by negative control.

Biogenic amine flux mediated by cloned transporters stably expressed in cultured cell lines: amphetamine specificity for inhibition and efflux

LLC-PK1 cells have been stably transfected with cDNAs encoding the human norepinephrine transporter (NET), rat dopamine transporter (DAT), and rat serotonin transporter. Using these cell lines, the specificity of each transporter toward agents that inhibit substrate influx and stimulate substrate efflux across the plasma membrane was examined. With 1-methyl-4-phenylpyridinium as a substrate for DAT and NET and serotonin as a substrate for the serotonin transporter, each transporter demonstrated a distinct pattern of inhibition by a panel of amphetamine derivatives and analogs, including amphetamine, methamphetamine (also known as "ecstasy"), p-chloroamphetamine, 3,4-methylenedioxymethamphetamine, methylphenidate (ritalin), and 5-methoxy-6-methyl-2-aminoindan. For each cell line expressing a single biogenic amine transporter, efflux of the accumulated substrate was stimulated by amphetamine derivatives, and this efflux was blocked by mazindol, an inhibitor of all three transporters. Of the amphetamine derivatives tested, some caused efflux at concentrations similar to those that inhibited transport. Other derivatives were much less effective at stimulating efflux than at inhibiting uptake. Methylphenidate caused little or no efflux, although it blocked uptake mediated by both NET and DAT. Other inhibitors of transport, such as cocaine, mazindol, citalopram, and nisoxetine, failed to stimulate efflux from these cells at concentrations that inhibited influx. The results suggest that potency toward individual plasma membrane biogenic amine transporters and the ability to release accumulated amine substrates are independent properties of each amphetamine derivative.

Population-Growth Potential of Epiphyas-Postvittana, the Lightbrown Apple Moth (Lepidoptera, Tortricidae) in Relation to Diet, Temperature and Climate

Life-history parameters and developmental rates of Epiphyas postvittana were determined for four natural food plants and Shorey's diet at each of six temperatures. The rate of development of larvae and the life-history parameters were influenced by both temperature and diet. The highest r(m) value was given by populations feeding on Plantago lanceolata, followed by those on Shorey's diet and Rumex crispus, all at 25 . 2 degrees C, then by Malus pumila at 19 . 9 degrees C and Trifolium repense at 25 . 2 degrees C. Zero population growth occurred at 7 . 1 and 30 . 7 degrees C. A life-table study of five geographical strains of the moth under non-variable conditions (constant temperature and artificial diet) showed that finite rate of increase (lambda) was significantly correlated with climatic features of habitats, viz. mean annual Values of temperature, rainfall and relative humidity. Peak values of lambda occurred at cooler temperatures, moderate levels of habitat moisture and high altitudes (500-1000 m); the Canberra population gave the highest value (lambda = 1 . 157), followed by Armidale (lambda = 1 . 152), Melbourne (lambda = 1 . 141), Mildura (lambda = 1 . 135) and Auckland (lambda = 1 . 118). Higher performance of E. postvittana on herbaceous plants than on woody plants suggests that it primarily evolved as a feeder on herbaceous plants.

[Insulin resistance and pregnancy induced hypertension]

Plasma glucose and serum insulin in oral glucose tolerance test (OGTT) were measured in 40 patients with pregnancy induced hypertension (PIH) and 30 normal pregnancies. Compared with the controls, serum insulin concentration, plasma glucose and their area under the curve (AUC) increased in 15 patient with severe PIH, in 0.5, 1, 2, 3 hours postload (P < 0.05) of OGTT. The relationship between diastolic blood pressure and integrated area under the curve for serum insulin concentration (r = 0.35, P < 0.05) were observed in 15 patients with severe PIH. The results indicated that patients with severe PIH are insulin resistant and hyperinsulinemic after an oral glucose load.

Cre-loxP-mediated gene replacement: a mouse strain producing humanized antibodies

BACKGROUND

The bacteriophage-derived Cre-loxP recombination system operates efficiently in mammalian cells. This system is particularly useful in gene-targeting experiments in the mouse, and has already been used to generate 'clean' deletions of target genes in the germ line, as well as to inactivate target genes in a conditional manner (based on regulated expression of the Cre recombinase). In principle, Cre-loxP-mediated recombination should also allow gene replacement, and thus the introduction of virtually any kind of mutation into the genome.

RESULTS

We used the Cre-loxP system, in mouse embryonic stem cells, to replace the mouse gene C gamma 1, which encodes the constant region of the heavy chain of IgG1 antibodies, with its human counterpart. The mutation was transmitted through the mouse germ line, and the resulting mutant mice were crossed with mice expressing kappa light chains with a human, instead of a mouse, constant region. Mice homozygous for both mutations produce humanized, kappa-chain-bearing IgG1 antibodies at the same level and efficiency as wild-type mice produce murine IgG1 antibodies. These animals should enable the ex vivo production of humanized, chimeric monoclonal antibodies specific for any antigen to which the mouse can respond.

CONCLUSIONS

Cre-loxP-mediated gene replacement is a simple and efficient general method of targeted mutagenesis in the mouse.

Deletion of a DNA polymerase beta gene segment in T cells using cell type-specific gene targeting

Deletion of the promoter and the first exon of the DNA polymerase beta gene (pol beta) in the mouse germ line results in a lethal phenotype. With the use of the bacteriophage-derived, site-specific recombinase Cre in a transgenic approach, the same mutation can be selectively introduced into a particular cellular compartment-in this case, T cells. The impact of the mutation on those cells can then be analyzed because the mutant animals are viable.

Comparison of the effects of antimitotic drugs on alpha-tubulin mRNA, microtubules and nicotinic receptor-mediated catecholamine secretion in adrenal chromaffin cells in culture

1. Four hour treatments of adrenal chromaffin cells with colchicine (10, 100 microM and 1 mM), tubulozole (10 microM) or podophyllotoxin (100 microM) decreases alpha-tubulin mRNA content. Vinblastine (10 microM) and taxol (10 microM), however, do not decrease alpha-tubulin mRNA content. 2. Immunocytochemical techniques demonstrate that 4 hr treatments with all of the antimitotic drugs (colchicine, podophyllotoxin, taxol, tubulozole and vinblastine) produce abnormal microtubule arrays. 3. The effects of 4 hr treatments with the antimitotic drugs on adrenal catecholamine secretion are all qualitatively the same; each drug selectively inhibits adrenal nicotinic acetylcholine receptor-stimulated catecholamine release, while having no inhibitory actions on release stimulated through noncholinergic mechanisms. 4. These studies demonstrate that autoregulation of tubulin synthesis occurs in cultured adrenal chromaffin cells. 5. All of the antimitotic drugs selectively inhibit nicotinic receptor-mediated adrenal catecholamine release under treatment conditions that affect adrenal microtubules. These results support the possibility that the actions of the antimitotic drugs on adrenal nicotinic receptors may involve microtubules.

[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.

Influence of Environmental-Conditions on Flight Duration of Epiphyas-Postvittana (Walker) (Lepidoptera, Tortricidae)

Flight responses of the light brown apple moth, Epiphyas postvittana (Walker), to changes in air temperature, atmospheric humidity, feeding and mating activities were studied under controlled conditions. Flights occurred within the air temperature range from 10 to 30-degrees-C, with the longest flight duration at 20-degrees-C for both sexes. A change of atmospheric humidity significantly influenced flight duration of females, but not of males, at 20-degrees-C. The longest flight duration of the female moths occurred at a relative humidity of 60%. Provision of honey solution or water improved flight duration of the moths aged three days or older. Mating increased flight duration of females from the age of three days onwards, presumably as a result of reduced body weight associated with oviposition.

Rapid increase in inositol phosphate levels in norepinephrine-stimulated vascular smooth muscle

We examined the correlation between agonist-stimulated increases in inositol phosphates and force development in vascular smooth muscle. Segments of rat tail artery were preincubated with [3H]inositol and treated with norepinephrine (10(-5) M) for 3-10 s. Tissue levels of inositol monophosphate (IP), inositol bisphosphate (IP2), and inositol trisphosphate (IP3) were measured. IP and IP2 increased significantly after 3 s of norepinephrine treatment. IP3 increased significantly after 5 s of norepinephrine treatment. Analysis of tissue extracts by high-pressure liquid chromatography demonstrated that the only isomer of IP3 present in any tissue extract was the 1,4,5-isomer [Ins(1,4,5)P3]. Contractile response to norepinephrine stimulation showed that the increase in inositol phosphates coincides well with the time course of force development. This is the first report demonstrating such an early increase in Ins(1,4,5)P3 in agonist-stimulated vascular smooth muscle. These results are consistent with the hypothetical role of Ins(1,4,5)P3 as a mediator linking agonist-receptor activation to increased intracellular calcium and force development in norepinephrine-stimulated vascular smooth muscle.

Most peripheral B cells in mice are ligand selected

Using amplified cDNA and genomic libraries, we have analyzed the VH gene repertoire of pre-B cells and various B cell subsets of conventional mice at the level of VH genes belonging to the J558 VH gene family. The sequence data were evaluated on the basis of a newly established list of 67 J558 VH genes that comprise approximately two-thirds of the J558 VH genes of the murine IgHb haplotype. The results of the analysis demonstrate that VH gene utilization in pre-B cells, although biased to some extent by B cell autonomous VH gene selection, scatters over the whole range of J558 VH genes present in the germline. In contrast, in mature, peripheral B cells comprising long-lived mu + delta high B cells as well as Ly-1 B cells, small overlapping sets of germline VH genes are dominantly expressed. The data indicate that the recruitment of newly generated B cells into the long-lived peripheral B cell pool is mediated through positive selection by internal and/or external antigens. Because of the absence of immunoglobulin class switching and somatic hypermutation, this process is different from the selection of memory B cells in T cell-dependent immune responses.

Full length mouse glycophorin gene constructed using recombinant polymerase chain reaction

Recently, an incomplete cDNA clone for a major mouse glycophorin gene, pGP315, and a genomic clone, pGX7 (which contains the first exon and nucleotide sequences around the transcription start sites) was isolated and sequenced by Matsui et al. (1). Since there were no available restriction sites for the construction of a full length mouse glycophorin A gene, the recombinant PCR technique was adapted to splice together the above two partial sequence clone inserts to obtain a full length recombinant DNA fragment (1053 bp) containing the proper sequence of mouse glycophorin A cDNA. The PCR reconstructed DNA fragments were verified by: gel electrophoresis to contain the expected sizes, hybridization to probes made from the DNA components before recombination, and confirmed by the restoration of a previously destroyed restriction enzyme site. The corrected gene sequence for pGP315 is also reported.

B cell development regulated by gene rearrangement: arrest of maturation by membrane-bound D mu protein and selection of DH element reading frames

In productively rearranged murine VH-DH-JH genes (encoding immunoglobulin heavy chain variable regions), the DH elements are preferentially used in one particular reading frame (RF1), although the recombination breakpoints at the DH-JH border vary. Despite this variability, the bias of RF usage is not due to cellular selection by antigen but is quantitatively established at the stage of DH-JH rearrangement: RF3 is counterselected on the basis of stop codons. RF2 allows the expression of a truncated mu chain (D mu protein) from most DH-JH joints. Using B cells in which the membrane exon of the mu chain is disrupted by homologous recombination on one of the two homologous chromosomes, we obtain evidence that membrane-bound D mu signals arrest of differentiation, presumably by preventing VH-DHJH joining. In addition to RF3 and RF2 counterselection, promotion of DH-JH joining in areas of sequence homology further enforces RF1 usage.

Enkephalin lowers vascular resistance in dog hindlimb via a peripheral nonlimb site

The intravenous administration of methionine enkephalin in anesthetized dogs produces an abrupt decline in mean arterial pressure, left ventricular pressure, and the maximal rate of left ventricular pressure development. All of these changes are prevented by receptor blockade with the opiate antagonist, naloxone. To evaluate peripheral vascular contributions to these responses, experiments were conducted in a constant pressure-isolated perfused hindlimb. In this model, the sharp decline in mean arterial pressure associated with enkephalin injection (5 micrograms/kg iv) coincided with an equally sharp decline in vascular resistance (rise in blood flow) in the hindlimb. Both were blocked by naloxone pretreatment (1 mg/kg). When equal doses of enkephalin were administered directly into the femoral inflow (external iliac artery), both arterial pressure and hindlimb flow responses were all but eliminated. This observation ruled out significant direct vascular interactions in the response and indicated a site of action outside the hindlimb. Additional catheters were placed in the bracheocephalic artery and descending aorta to permit the comparison of arterial injections conducted, respectively, into the cerebral or abdominal circulations. Injections introduced into the descending aorta consistently produced the greatest response, followed by injections (in descending order of effectiveness) into the jugular, the brachiocephalic, and external iliac. The response in the hindlimb vasculature was initiated at a site somewhere between the diaphragm and terminal aorta. The vascular response to enkephalin was subsequently eliminated by blocking ganglionic transmission with the nicotinic antagonist mecamylamine. These observations suggest that the opioids probably interrupt local vasomotor traffic via opiate receptors in regional sympathetic ganglia or in the spinal cord.

Improved prenatal detection of fra(X)(q27.3): methods for prevention of false negatives in chorionic villus and amniotic fluid cell cultures

The reliable detection of fra(X)(q27.3) in prenatal samples is important for providing genetic counseling. We have identified 5 new cases of prenatal fragile X [fra(X)] detection in 3 chorionic villus sample (CVS) and 2 amniotic fluid (AF) cell cultures. In 4 of the 5 cases, either excess thymidine (THY) or a combination of THY and 5-fluorodeoxyuridine (FUdR) was clearly superior to FUdR alone as fra(X) inducers. Amniocytes from one case were cultured only in RPMI-1640 and later exposed to FUdR or THY separately. They showed only 2% fra(X) while parallel cultures initiated in Chang medium and incubated in RPMI for at least 7 days (recovery) before fra(X) induction exhibited strikingly increased fra(X) frequencies. Chang medium alone will not allow fra(X) induction in AF (Jenkins EC, Brown WT [1986]: "Genetic Disorders and the Fetus: Diagnosis, Prevention and Treatment." New York: Plenum Press, pp 185-204). Now, using CVS cells, we report that only 1% and 0% fra(X) were detected using FUdR or THY in cells cultured in RPMI for 4 days after removal from Chang medium. Cells with 7 days "recovery" in RPMI exhibited increases from 2 to 6%. Therefore, we have found that Chang medium is very helpful when the appropriate recovery time in another medium is allowed before fra(X) induction. Some false negative reports can be attributed to: induction in Chang medium alone; lack of sufficient recovery time after initiating cells in Chang before induction; and unavailability of the excess THY fra(X) induction system.(ABSTRACT TRUNCATED AT 250 WORDS)

Distribution of autosomal fragile sites in specimens cultured for prenatal fragile X diagnosis

We reviewed the distribution of autosomal fragile sites (FS) and spontaneous chromosome breaks or gaps (CB) at chromosome locations other than those recognized as FS from 100 amniotic fluid samples (AF), 19 chorionic villus samples (CVS), and 5 percutaneous umbilical blood samples (PUBS) referred for fragile X [fra(X)] analysis. We present data on the degree of expression of autosomal fragility in AF, CVS, and PUBS samples, and the relationship between degree of expression and induction system. The most common observed FS were: 3p14, 9p32, and 6q26 in AF; 9q32, 3q27, and 8q22 in CVS; and 3p14, Xq22, and 16q23 in PUBS cases. Distribution of FS and CB, when compared by induction system, was not found to be identical. Our data also indicate that the presence of any particular FS cannot be used as an indicator for the effectiveness of the fra(X) induction system in prenatal samples.

Naloxone enhances cardiac contractile responses to epinephrine without altering epinephrine uptake from plasma

Naloxone potentiates the inotropic effect of selected beta-agonists in the canine isolated heart. This could be accomplished by elevating circulating catecholamines through a reduction in their disposal or by the facilitation of events at or subsequent to the cardiac beta-receptor. To evaluate the first hypothesis, epinephrine was infused intravenously into a blood-perfused isolated heart-lung preparation. Catecholamines were determined and myocardial and pulmonary epinephrine uptakes were calculated. Naloxone enhanced the inotropic effect (peak +dP/dt) during epinephrine infusion. Coronary blood flow and coronary venous epinephrine concentrations were also elevated after naloxone. Calculated myocardial and pulmonary uptake of epinephrine were, however, unaltered by naloxone. The increased coronary sinus epinephrine after naloxone was evaluated further in experiments redesigned to eliminate the influence of changing coronary blood flow. Epinephrine was infused into the left common coronary and coronary blood flow as maintained constant, 100% above the resting flow rate. Naloxone enhanced the contractile response to epinephrine without altering coronary artery or coronary sinus epinephrine concentrations or myocardial epinephrine uptake. By comparison, corticosterone, an extra-neuronal uptake inhibitor, also potentiated the inotropic effect of infused epinephrine under identical conditions. However, corticosterone was accompanied by a significant increase in coronary sinus epinephrine concentration and a decrease in myocardial epinephrine uptake. We therefore concluded that the ability of naloxone to enhance the inotropic effect of epinephrine is not mediate through an increase in plasma epinephrine concentration secondary to a decrease in the disposal of circulating catecholamines.

Plasmodium falciparum: analysis of chromosomes separated by contour-clamped homogenous electric fields

We have established improved conditions for separating the chromosomes of Plasmodium falciparum by pulsed field gradient gel electrophoresis (PFG) using a contour-clamped homogenous electric field (CHEF) apparatus. Thirteen clearly separable chromosomal bands were reproducibly isolated from the strain FCR3 and their sizes have been determined. Evidence that indicates one band may contain two chromosomes is presented. The relationship between the PFG separable DNA and the number of unique chromosomes in P. falciparum is considered. We have established a relationship between the maximum resolvable sizes of the chromosomes and the pulse times. The chromosomal location of twenty-seven P. falciparum DNA probes is also reported.

Sequence homologies, N sequence insertion and JH gene utilization in VHDJH joining: implications for the joining mechanism and the ontogenetic timing of Ly1 B cell and B-CLL progenitor generation

Sequence analysis of rearranged VHDJH genes of B lineage cells from various stages of ontogeny indicates that short sequence homologies at the breakpoints of recombination contribute to V region gene assembly. Such homologies are regularly seen at DJH junctions of neonatal pre-B cells, most of which do not contain N sequences. In the same cells, but not at later developmental stages, preferential usage of the JH1 element is observed. After birth, N sequence insertion increases with time and is always more prominent at the VHD border than the DJH border. In pre-B cells from adult animals and in mature B cells, in cases where N sequences were not detectable, sequence homologies at the DJH border were found in only half of the instances. This lower incidence could be due to N sequence addition to one of the recombining DNA ends and/or cellular selection. Inspection of VHDJH junctions for N sequence insertion, sequence homologies at the DJH border and JH1 usage allows the estimation of the timepoint in ontogeny at which particular B cell subsets are seeded into the immune system. Specifically, the present data show that the cells of the Ly1 B cell subset are generated not only neonatally but also beyond the first weeks of life. However, the DJH junctions of the progenitors of chronic B cell leukemias which originate from the same B cell subset resemble those of neonatal pre-B cells, suggesting that these cells have already undergone a transforming event at this early developmental stage.

Progress toward an internal control system for fragile-X induction by 5-fluorodeoxyuridine in whole-blood cultures

We have been attempting to develop a consistently reliable internal control to assure the effectiveness of the 5-fluorodeoxyuridine (FUdR) fragile-X [fra(X)] induction system. We carried out a systematic study of whole-blood specimens cultured from 56 individuals from two different laboratories. An analysis of nearly 9,000 cells demonstrated: (1) the importance of establishing baseline levels of fragile sites in each laboratory, and (2) that a combination of common fragile sites (different for each laboratory) could serve as a consistently reliable indicator of the effectiveness of the FUdR fra(X) induction system. It was suggested that a non-FUdR culture(s) should be incorporated into a laboratory's fra(X)-screening protocol, so that if there are any doubts about the effectiveness of the FUdR system a comparison to background or spontaneously occurring fragile sites can be made within the laboratory. Repeat cultures are recommended where no increase in common fragile-site frequency is observed in the FUdR induction system, and where fra(X) was strongly suspected but not found. In addition, the necessity of using more than one fra(X) induction system in whole-blood cultures was demonstrated, including the effectiveness of an FUdR/excess thymidine double-induction system. Finally, 2 cases of apparent mosaicism for Klinefelter syndrome in fra(X) individuals were observed.