Involvement of calcitonin gene-related peptide in the modulation of human myometrial contractility during pregnancy

Calcitonin gene-related peptide (CGRP) is a potent vasodilator and relaxes smooth muscle of a variety of tissues, but the effects of CGRP on human myometrial contractions and the changes in CGRP receptors (CGRP-Rs) in human myometrium have not been described. We report that CGRP induced dose-dependent relaxation in spontaneously contracting myometrium from pregnant women. This relaxation effect is diminished in myometrium obtained from patients during labor and in the nonpregnant state. CGRP-induced relaxations are inhibited by a CGRP-R antagonist (CGRP(8-37)), a soluble guanylate cyclase inhibitor (LY(83583)), and a nitric oxide synthase inhibitor (L-NAME). Both Western blotting and mRNA analysis showed that CGRP-Rs are present in human myometrium, and that the expression of these receptors is increased during pregnancy and decreased during term labor. Immunofluorescent staining revealed that CGRP-Rs are abundant in the myometrial cells of pregnant women who are not in labor, and are minimal in uterine specimens from women in labor and in the nonpregnant state. We conclude that increased CGRP-Rs in myometrium, and resulting enhanced myometrial sensitivity to CGRP, may play a role in maintaining human myometrium in a quiescent state during pregnancy, and that a decline in the CGRP-Rs at term could contribute to the initiation of labor.

Transcription of cspA, the gene for the major cold-shock protein of Escherichia coli, is negatively regulated at 37 degrees C by the 5'-untranslated region of its mRNA

The gene for CspA, the major cold-shock protein in Escherichia coli, is tightly regulated at both optimal and low temperatures. While CspA is drastically induced after temperature downshift, it is hardly detectable at 37 degrees C. Here we demonstrate that the deletion of parts of the 5'-untranslated region (5'-UTR) of the cspA mRNA results in constitutive expression of CspA at 37 degrees C. By analyzing the amounts and the stabilities of the mRNAs produced from the deletion constructs, we rule out the possibility that the CspA production is due to the stabilization of the mutant mRNAs. We propose that significant premature termination or pausing occurs during the transcription of the unusually long 5'-UTR of the cspA mRNA at 37 degrees C, which represents a new mechanism that contributes to the tight repression of CspA production at higher temperature.

p21Waf1/Cip1/Sdi1 induces permanent growth arrest with markers of replicative senescence in human tumor cells lacking functional p53

We have shown previously that wild type p53 can rapidly induce replicative senescence in EJ human bladder carcinoma cells lacking functional p53. A major effector of p53 functions is p21Waf1/Cip1/Sdi1, a potent cyclin-dependent kinase inhibitor. p21Waf1/Cip1/Sdi1 has been shown to be involved in both p53 dependent and independent control of cell proliferation, differentiation and death. To directly investigate the effects of p21Waf1/Cip1/Sdi1 in the p53 response observed in EJ tumor cells, we established p21Waf1/Cip1/Sdi1 inducible lines using the tetracycline-regulatable vector system. p21Waf1/Cip1/Sdi1 induction caused irreversible cell cycle arrest in both G1 and G2/M, and diminished Cdk2 kinase activity. In addition, p21Waf1/Cip1/Sdi1 induction led to morphological alterations characteristic of cells undergoing replicative senescence with morphological, biochemical and ultrastructural markers of the senescent phenotype. Furthermore, sustained p21Waf1/Cip1/Sdi1 induction sensitized EJ cells to apoptotic cell death induced by mitomycin C, a cross-linking DNA damaging agent. These findings support the function of p21Waf1/Cip1/Sdi1 as an inducer of replicative senescence and a major mediator of this phenomenon in response to p53. Moreover, our results imply that therapeutic intervention in human cancers might be aimed at sustained elevation of p21Waf1/Cip1/Sdi1 expression.

Inverse relationship between severity of experimental pyelonephritis and nitric oxide production in C3H/HeJ mice

The contribution of nitric oxide to host resistance to experimental pyelonephritis is not well understood. We examined whether the inhibition of nitric oxide synthesis alters the sensitivity of lipopolysaccharide (LPS) responder (C3H/HeN) and nonresponder (C3H/HeJ) mice to experimental Escherichia coli pyelonephritis. C3H/HeJ and C3H/HeN mice were implanted subcutaneously with minipumps containing an inhibitor of nitric oxide, NG-nitro-L-arginine methyl ester (L-NAME), or a corresponding vehicle. Ascending urinary tract infection by bladder catheterization with two strains of E. coli, an O75 strain bearing Dr fimbriae and an O75 strain bearing P fimbriae, was developed in tested animals. Twenty-four hours following bladder infection, the kidneys of C3H/HeN and C3H/HeJ mice were colonized at a similar rate. However, 5 weeks postinoculation, C3H/HeN mice cleared infection while C3H/HeJ mice showed persistent colonization. Twenty-four hours following infection, C3H/HeN mice treated with L-NAME showed no significant increase of renal tissue infection compared to the saline-treated control group. However, L-NAME-treated C3H/HeJ mice showed an approximately 100-fold increase in E. coli infection rate compared to the saline-treated controls in the Dr+ group but showed no change compared to those in the P+ group. Dissemination of Dr+ E. coli but not P+ E. coli to the liver and uterus was significantly enhanced with L-NAME treatment in C3H/HeJ mice only. Nitric oxide had no direct killing effect on E. coli in vitro. Nitrite production by various organs was found to be significantly lower in C3H/HeJ mice than in C3H/HeN mice. Alteration of nitric oxide and LPS responsiveness was significantly associated with the increased sensitivity of C3H/HeJ mice to experimental Dr+ but not to P+ E. coli pyelonephritis. These findings are consistent with the hypothesis that nitric oxide synthase activity in concert with LPS responsiveness may participate in the antibacterial defense mechanisms of the C3H mouse urinary tract. This phenomenon is strain dependent and possibly related to the invasive properties of E. coli.

Passive protective effect of egg-yolk antibodies against enterotoxigenic Escherichia coli K88+ infection in neonatal and early-weaned piglets

The protective effects of egg-yolk antibodies obtained from hens immunized with fimbrial antigens from a local strain (Escherichia coli K88+ MB, Manitoba, Canada) of K88+ piliated enterotoxigenic E. coli (ETEC) were evaluated in 3- and 21-day-old piglets in which ETEC diarrhea was induced and also in early-weaned piglets in a commercial farm. The results demonstrated that the E. coli K88+ MB-induced diarrhea in 3-day-old piglets was cured 24 h after treating with egg-yolk antibodies while those treated with egg-yolk powder from conventional hens continued to have diarrhea and 62.5% of them died of severe diarrhea. For 21-day-old weaned piglets, those fed egg-yolk antibodies had transient diarrhea, positive body weight gains and 100% survival during the period of the experiment, whereas control piglets that were treated with placebo had severe diarrhea and dehydration and some died within 48 h after infection. In the field trial, the incidence and severity of diarrhea of 14-18-day-old weaned piglets fed egg-yolk antibodies were much lower than in those fed a commercial diet containing an antibiotic. These results indicate that the neonatal and early-weaned piglets that received the egg-yolk antibodies were protected against ETEC infection.

Nitric oxide reverses prostaglandin-induced inhibition in ovarian progesterone secretion in rats

The present studies were undertaken to determine whether nitric oxide (NO) is involved in the regulation of ovarian progesterone and oestradiol secretion in rats. Immature female Sprague-Dawley rats at 27 days of age were injected s.c. with 4 IU pregnant mare's serum gonadotrophin (PMSG) and were killed 72 h after the injection. The ovaries were collected, weighed and cultured in Dulbecco's modified Eagle's medium containing saline, NO donor, NO synthesis inhibitor or prostaglandin F2 alpha (PGF2 alpha). After 24 h culture, the medium concentrations of progesterone and oestradiol were measured by radioimmunoassay. Results showed that: (i) diethylenetriamine (DETA)/NO (1 x 10(-6), 1 x 10(-5), 1 x 10(-4) M), an NO donor, caused a dose-dependent increase in progesterone synthesis (355 +/- 43, 443 +/- 46, 647 +/- 55 ng/g ovary respectively, P < 0.01) with a concomitant decrease in ovarian oestradiol secretion (408.1 +/- 50.7, 272.9 +/- 28.2, 132.6 +/- 34.6 pg/g ovary respectively, P < 0.01); (ii) neither progesterone nor oestradiol concentrations in the culture medium were altered by DETA without NO; (iii) NG-nitro-l-arginine methyl ester (1 x 10(-4) M), an inhibitor of NO synthesis, did not significantly affect progesterone and oestradiol secretion by rat ovaries; (iv) PGF2 alpha(1 x 10(-6) M) caused a fall in progesterone and oestradiol synthesis; (v) co-incubation with DETA/NO, significantly reversed the PGF2 alpha-induced decrease in progesterone concentrations from 184 +/- 29 to 388 +/- 60 ng/g (P < 0.01), but not that of oestradiol. It can be concluded that NO up-regulates progesterone secretion and down-regulates oestradiol secretion in rat ovaries, and NO can reverse PGF2 alpha-induced inhibition in ovarian progesterone secretion.

Regulation of inducible nitric oxide synthase messenger ribonucleic acid expression in pregnant rat uterus

Nitric oxide synthases catalyze the synthesis of the biomediator, nitric oxide, from L-arginine in a variety of tissues. The expression and regulation of inducible isoform of nitric oxide synthase (NOS II) in the uterus were assessed in this study by reverse transcription-polymerase chain reaction with the use of specific primers. Results showed the following: 1) NOS II mRNA expression in the rat uterus was substantially increased during pregnancy and decreased during labor at term; 2) RU-486 (an antagonist of progesterone) induced preterm labor and was associated with a marked decrease in NOS II mRNA expression to 60.9%, 20.3%, and 2.9% at, respectively, 6, 12, and 24 h after treatment compared with the control value (100%); 3) progesterone administration in pregnant rats significantly increased uterine NOS II gene expression (374.1% vs. 100%); 4) NOS II mRNA in the uterus was significantly reduced by prostaglandin F2alpha (PGF2alpha; 11.6% vs. 100% in control); 5) treatment with progesterone prevented PGF2alpha-induced inhibition in NOS II mRNA expression; 6) ICI 164384, an antiestrogen, significantly increased serum progesterone concentration and stimulated NOS II expression by the uterus in a time-dependent manner; 7) as shown by immunofluorescent studies, cells stained by NOS II antibodies were apparent in the decidual compartment as well as in areas between myometrial cell bundles in the pregnant rat uterus. The density of staining decreased in the specimens at labor and postpartum. We conclude that NOS II gene expression in the rat uterus was enhanced during pregnancy and decreased during labor and postpartum. NOS II in rat uterus is up-regulated by progesterone and down-regulated by estrogens and prostaglandins, consistent with their role in uterine activity regulation during pregnancy and labor.

Uterine relaxation responses to calcitonin gene-related peptide and calcitonin gene-related peptide receptors decreased during labor in rats

OBJECTIVES

Our purpose was to investigate (1) whether uterine relaxation responses to calcitonin gene-related peptide are differentially regulated during pregnancy and labor, (2) the involvement of nitric oxide in smooth muscle relaxant action of calcitonin gene-related peptide in the rat uterus, (3) whether receptors for calcitonin gene-related peptide are expressed in rat uterus, and if so (4) whether the concentrations of these receptors are differently regulated during pregnancy and labor.

STUDY DESIGN

Rats were killed on day 18 of gestation, at the time of spontaneous labor, or postpartum day 2. The uteri were removed for in vitro contractility measurements, nitric oxide production, and calcitonin gene-related peptide receptor binding assay.

RESULTS

(1) Calcitonin gene-related peptide induced a dose-dependent relaxation in spontaneously contracting uterine strips from pregnant rats on day 18 of gestation; (2) the relaxation effects of calcitonin gene-related peptide on the uterus were decreased during spontaneous delivery at term and post partum compared with that during pregnancy; (3) calcitonin gene-related peptide-induced relaxation was inhibited by pretreatment of the uterine tissue with a calcitonin gene-related peptide receptor antagonist, calcitonin gene-related peptide(8-37); (4) nitric oxide synthesis inhibitor (N(G)-nitro-L-arginine methyl ester) and soluble guanylate cyclase inhibitor (LY83583) significantly decreased calcitonin gene-related peptide-induced relaxation of the rat uterus during pregnancy; (5) calcitonin gene-related peptide increased the uterine nitric oxide production in pregnant rats, and this increase was obliterated in the presence of calcitonin gene-related peptide(8-37); and (6) calcitonin gene-related peptide receptors are present in rat uterus, and the concentration of these receptors dramatically increases during pregnancy and decreases during labor at term.

CONCLUSIONS

Calcitonin gene-related peptide inhibits uterine spontaneous contractions in rats during pregnancy but not during labor and post partum. The inhibitory effects of calcitonin gene-related peptide on uterine contractility appear to be modulated, at least in part, by the activation of nitric oxide generation in the rat uterus. Changes in calcitonin gene-related peptide receptors could contribute to the changes in calcitonin gene-related peptide-mediated uterine relaxation during pregnancy and labor.

[The relationship between HBV infection and injury of tubuli and interstitium in IgA nephropathy]

OBJECTIVE

To clarify the correlation between HBV infection and the injury of tubuli and interstitium of IgA nephropathy.

METHODS

Renal biopsy specimens from 91 patients with primary IgA nephropathy were investigated by use of in situ hybridization (HBV DNA), immunohistochemistry (HBsAg, HBcAg, CD3, CD8) and HBV DNA, HBAg-CD43 double staining techniques.

RESULTS

The positive rate of HBAg in renal tissue as detected by immunohistochemistry was 69.2% and that of HBV DNA detected by in situ hybridization was 42.9%. Double staining showed that HBV DNA positive tubular epithelial cells might coexpress HBsAg and/or HBcAg. The numbers of the infiltrated CD3+ cells and CD8+ cells in cases with positive HBV infections markers were significantly higher than those of cases without infection (P < 0.01). In addition, CD43+ T lymphocytes infiltrated around or invaded into the tubuli walls which had positive HBcAg or HBsAg expression.

CONCLUSION

After HBV infection, the renal cells could express HBAg and induce infiltration of CD3+ cells and CD8+ cells, resulting in aggravation of the injury of tubuli and interstitium. Therefore, it is considered that HBV infection might play an important role in the occurrence and progress of IgA nephropathy.

Immunohistochemical localization of constitutive and inducible cyclo-oxygenases in rat uterus during the oestrous cycle and pregnancy

The uterus is a rich source of eicosanoids synthesized from arachidonic acid metabolism through the cyclo-oxygenase pathway. Two isoforms of cyclo-oxygenase, constitutive (COX-I) and inducible (COX-II) enzyme, have been reported. In the present study, we have immunohistochemically mapped the distribution of both COX-I and COX-II during various physiological states of the rat uterus. Uterine tissue was collected from female rats (a) during different stages of the oestrous cycle, (b) on days 1, 4, 8 and 18 of gestation, (c) after spontaneous delivery and (d) post partum, and fixed in Bouin's fixative. After paraffin wax embedding, 5-microm-thick sections were immunohistochemically stained by the ABC technique. Observation of the stained sections under the light microscope revealed that, in non-pregnant rat uterus, both COX-I and COX-II were abundantly expressed in the endometrium, with minimal staining observed in the myometrium. Staining was more prominent in epithelial cells than in stromal cells. The intensity of staining in epithelial cells was highest at pro-oestrus and oestrus and lowest at dioestrus. In pregnant rats, although the expression of both COX-I and COX-II was localized primarily to the endometrium with very little staining in the myometrium on day 1 of gestation, both of these enzymes were also apparent in myometrial cells by day 4 of gestation. The staining intensity of endometrial and myometrial cells increased further with the progression of gestation, being maximal at the time of spontaneous delivery. During the post-partum period, however, the staining intensity for both of the enzymes in endometrium and myometrium was decreased. Thus, our studies show that the expression of cyclo-oxygenases in various uterine cells vary with the oestrous cycle and with pregnancy. Furthermore, prominent increases in the expression of cyclo-oxygenases in the myometrium during pregnancy and parturition imply that the cyclo-oxygenase system in the myometrium may play a major role in modulating uterine contractility during pregnancy and labour.

Role and regulation of nitric oxide in the uterus during pregnancy and parturition

OBJECTIVE

To review the English-language literature as it relates to the role and regulation of uterine nitric oxide (NO) during pregnancy and parturition, special emphasis being placed on the interactions of NO with other uterotonic agents.

METHODS

A thorough literature review of the English-language literature using a Medline search was performed.

RESULTS

Current data support the view that NO is generated in the uterus and inhibits uterine contractility. Gestation, parturition, steroid hormones, and prostaglandins modulate both the generation and the effects of NO on the uterus. The changes in NO and its effects are consistent with the theory that NO plays a role in uterine quiescence during pregnancy. A change in this system at term or preterm could play a role in inhibition of labor and delivery.

CONCLUSION

Uterine NO may play a role in maintaining uterine quiescence during pregnancy.

The CspA family in Escherichia coli: multiple gene duplication for stress adaptation

CspA was originally found as the major cold-shock protein in Escherichia coli, consisting of 70-amino-acid residues. It forms a beta-barrel structure with five anti-parallel beta-strands and functions as an RNA chaperone. Its dramatic but transient induction upon cold shock is regulated at the level of transcription, mRNA stability and translation. Surprisingly, E. coli contains a large CspA family, consisting of nine genes from cspA to cspI. Phylogenetic analysis of these gene products and the cold-shock domain of human YB-1 protein reveals that there are two major branches in the evolution of CspA homologues: one branch for CspF and CspH, and another for all the other known CspA homologues from both prokaryotes and eukaryotes. The locations of these genes on the E. coli chromosome suggest that the large CspA family probably resulted from a number of gene duplications and, after subsequent adaptation, resulted in specific groups of genes that respond to different environmental stresses; for example, cspA, cspB and cspG for cold-shock stress and cspD for nutritional deprivation. The E. coli CspA family will be discussed in terms of their structures and functions, and their gene structures and regulation.

Role of the cold-box region in the 5' untranslated region of the cspA mRNA in its transient expression at low temperature in Escherichia coli

Upon temperature downshift, a group of proteins called cold shock proteins, such as CspA, CspB, and CsdA, are transiently induced in Escherichia coli. However, when the 5' untranslated region (5' UTR) of cspA mRNA is overproduced at low temperature, the expression of cold shock genes is prolonged or derepressed. It has been proposed that this effect is due to highly conserved 11-base sequences designated the "cold box" existing in the 5' UTRs of cspA, cspB, and csdA. Here, we demonstrate that the overproduction of the 5' UTR of not only cspA but also cspB and csdA mRNAs causes derepression of all three genes at the same time. Conversely, when the cold-box region was deleted from the cspA 5' UTR its derepression function was abolished. The amount of mRNA from the chromosomal cspA gene was much higher in cells overproducing the wild-type 5' UTR by means of a plasmid than it was in cells overproducing the cold-box-deleted 5' UTR. The stability of the chromosomal cspA mRNA in cells overproducing the wild-type 5' UTR was almost identical to that in cells overproducing the cold-box-deleted 5' UTR. Therefore, the derepression of cspA caused by overproduction of 5' UTR at the end of the acclimation phase occurs at the level of transcription but not by mRNA stabilization, indicating that the cold-box region plays a negative role in cspA transcription in cold shock-adapted cells. The role of the cold-box region was further confirmed with a cspA mutant strain containing a cold-box-deleted cspA gene integrated into the chromosome, which showed a high level of constitutive production of CspA but not CspB during exponential growth at low temperature.

Molecular cloning of a cDNA encoding the neuropeptides APGWamide and cerebral peptide 1: localization of APGWamide-like immunoreactivity in the central nervous system and male reproductive organs of Aplysia

While much is known about the neural and endocrine mechanisms that control egg laying in the gastropod mollusk Aplysia, relatively little is known about the regulation of male reproductive activity in this simultaneous hermaphrodite. In the present study, we have cloned and sequenced a cDNA that encodes a precursor protein, the predicted posttranslational processing of which presumably generates nine copies of the neuropeptide Ala-Pro-Gly-Trp-NH2 (APGWamide), five connecting peptide sequences, and a C-terminal peptide. The sequence of one connecting peptide is identical to the previously characterized cerebral peptide 1. Northern blot analysis identified two major APGWamide mRNA transcripts (approximately 1.3 kb, approximately 2.4 kb), which were present in central nervous system ganglia, but were most abundant in the right cerebral and right pedal ganglia. Immunohistochemical studies using sexually mature Aplysia demonstrated that the vast majority of APGWamide-like immunoreactivity was localized in 30-40 neurons along the anterior and medial margins of the right cerebral ganglion and in a cluster of 15-20 neurons in the right pedal ganglion. A total of only about ten immunoreactive neurons were located in other ganglia. Immunohistochemistry also demonstrated that APGWamide was present in the reproductive organs that participate in the storage or transport of sperm, including the small hermaphroditic duct (site of sperm storage before mating), the white hemiduct (also known as the copulatory duct), and penial complex. As a group, these data suggest that APGWamide may play a role in regulating male reproductive function in Aplysia, as it does in other gastropods.

Lethal outcome of uterine infection in pregnant but not in nonpregnant rats and increased death rate with inhibition of nitric oxide

PROBLEM

Limited information is available on potential differences in sensitivity to urogenital infections between pregnant and nonpregnant hosts.

METHOD OF STUDY

In this study, we evaluated Escherichia coli infectious complications in pregnant and nonpregnant rats and the effect of nitric oxide (NO) inhibitor, NG-nitro-L-arginine methyl ester (L-NAME), on the outcome of an experimental uterine infection.

RESULTS

Of the infected pregnant animals, 31% were found dead in 24-48 hr. The death rate was increased 2-fold (66%) with L-NAME treatment. No deaths occurred in nonpregnant animals with or without L-NAME treatment. The rate of uterine infection in pregnant animals was about 10-fold higher than in nonpregnant animals.

CONCLUSION

We propose that infectious complications of pregnancy may be related to gestation-dependent sensitivity to the pathogenic microorganism and the host NO status.

Deletion analysis of cspA of Escherichia coli: requirement of the AT-rich UP element for cspA transcription and the downstream box in the coding region for its cold shock induction

In order to analyse the mechanism of cold shock induction of CspA, a major cold shock protein of Escherichia coli, deletion analysis of the cspA gene was carried out. It was found that (i) the AT-rich sequence (-47 to -38) upstream of the cspA -35 region may act as the UP element playing a crucial role in cspA transcription at both 37 degrees C and 15 degrees C; (ii) the unusually long 5'-UTR of the cspA mRNA has negative effects on cspA expression at 37 degrees C; and (iii) in contrast, the 5'-UTR exerts a positive effect on mRNA stabilization at low temperature. Furthermore, it was demonstrated that the 14 base downstream box (DB) locating 12 bases downstream of the initiation codon of the cspA mRNA and complementary to a region near the decoding region of 16S rRNA was essential for the mRNA translation during the growth lag acclimation phase immediately after cold shock. During this phase, translation of non-cold shock gene mRNAs is blocked, since they require cold shock-specific ribosomal factors for the formation of the translation initiation complex. It is proposed that DB in cold shock mRNAs allows the formation of a stable initiation complex at low temperature in the absence of the cold shock ribosomal factors.

Novel mutations and a mutational hotspot in the MODY3 gene

Maturity-onset diabetes of the young 3 (MODY3) is a type of NIDDM caused by mutations in the transcription factor hepatocyte nuclear factor-1alpha (HNF-1alpha) located on chromosome 12q. We have identified four novel HNF-1alpha missense mutations in MODY3 families. In four additional and unrelated families, we observed an identical insertion mutation that had occurred in a polycytidine tract in exon 4. Among those families, one exhibited a de novo mutation at this location. We propose that instability of this sequence represents a general mutational mechanism in MODY3. We observed no HNF-1alpha mutations among 86 unrelated late-onset diabetic patients with relative insulin deficiency. Hence mutations in this gene appear to be most strongly associated with early-onset diabetes.

The HumD21S11 system of short tandem repeat DNA polymorphisms in Japanese and Chinese

HumD21S11 is a short tandem repeat DNA polymorphic system with a complex basic structure of (TCTA)4-6 (TCTG)5-6 (TCTA)3 TA (TCTA)3 TCA (TCTA)2 TCCA TA (TCTA)n. Using the allelic ladder prepared by us, the distribution of alleles among Japanese and Chinese was investigated, and four new alleles 28.2, 34, 35.2, and 36.2, were discovered. DNA sequencing was performed on the newly found alleles as well as on family samples and led to the discovery of different gene structures within alleles 28 and 32. Forensic materials, including hairs and seminal stains, were tested in parallel with blood samples from the same individual and were successfully typed for D21S11.

Promoter-independent cold-shock induction of cspA and its derepression at 37 degrees C by mRNA stabilization

The gene for CspA, the major cold-shock protein of Escherichia coli is known to be dramatically induced upon temperature downshift. Here, we report that three-base substitutions around the Shine-Dalgarno sequence in the 159-base 5'-untranslated region of the cspA mRNA stabilizes the mRNA 150-fold, resulting in constitutive expression of cspA at 37 degrees C. This stabilization was found to be at least partially due to resistance against RNase E degradation. The cold-shock induction of cspA was also achieved by exchanging its promoter with the non-cold-shock Ipp promoter. The results presented indicate that the cspA gene is efficiently transcribed even at 37 degrees C. However, the translation of the cspA mRNA is blocked because of its extreme instability at 37 degrees C. The presented results also demonstrate that the cspA gene is constitutively transcribed at all temperatures; however, its expression at 37 degrees C is prevented by destabilizing its mRNA.

Complete growth inhibition of Escherichia coli by ribosome trapping with truncated cspA mRNA at low temperature

BACKGROUND

CspA, the major cold-shock protein of Escherichia coli, is transiently induced upon temperature downshift and considered to play an important role in low-temperature adaptation.

RESULTS

Overproduction of truncated cspA mRNAs retaining translational ability was found to completely block cell growth at low temperatures. This effect was termed 'low-temperature antibiotic effect of truncated cspA expression (LACE)'. In contrast to the significant reduction of polysomes in normal cells upon cold shock, cells under LACE maintained a high polysome profile, producing only truncated cspA products. Growth inhibition of cells under LACE was suppressed when CspA was overproduced together with the truncated cspA mRNA.

CONCLUSION

LACE is caused by the overproduction of a truncated cspA mRNA in the absence of CspA production, which in turn traps all the cellular ribosomes in a non-adaptive form incapable of forming initiation complexes with other cellular mRNAs. LACE may provide a novel approach to the development of a new antibiotic.

Response of pediatric malignant solid tumors following ifosfamide or ifosfamide/carboplatin/etoposide: a single hospital experience

One hundred thirty-eight pediatric patients have received treatment for malignant solid tumors with ifosfamide with mesna, and 71 have received a combination with ifosfamide/carboplatin/etoposide (ICE). Responses were obtained in many types of pediatric tumors, yet comparison of responses was not possible because of inadequate numbers of tumors of differing histiotypes. Comparison of results between patients with all tumors treated with ifosfamide or ICE indicated that there was a higher response rate for patients treated with ICE, with an estimated odds ratio of 2.74 (95% C.I. 1.45-5.179). Excluding patients without prior chemotherapy and radiotherapy, the odds ratio for 2.801 (95% C.I. 1.45-5.4) suggests a similar result. There remain no guarantees that the more costly treatment with ICE, which requires cytokine support, will offer therapeutic benefits against resistant solid tumors.

The role of the 5'-end untranslated region of the mRNA for CspA, the major cold-shock protein of Escherichia coli, in cold-shock adaptation

During cellular adaptation to low temperature, Escherichia coli transiently synthesizes the major cold-shock protein CspA. It was found that adaptation to cold shock is blocked when the 143-base sequence of the 5' untranslated region (5' UTR) of the cspA mRNA is overproduced. The overproduction of this UTR at 15 degrees C caused the synthesis of not only CspA but also other cold-shock proteins such as CspB and CsdA to be no longer transient but rather prolonged. In addition, inhibition of both the synthesis of cellular proteins other than cold-shock proteins and cell growth was observed. Interestingly, when CspA was also overproduced together with the 5' UTR, normal cold-shock adaptive response was resumed without a prolonged lag period of cell growth. This indicates that the 5' UTR of the cspA mRNA and its gene product CspA play a critical role in the regulation of the expression of cold-shock genes and cold-shock adaptation. An 11-base common sequence (cold box) was found in the 5' UTRs of cspA, cspB, and csdA mRNAs. Indeed, the 25-base sequence within the 5' UTR of the cspA mRNA containing the cold-box sequence was able to prolong CspA production at 15 degrees C. We propose that a putative repressor binds to the cold-box sequence of the cold-shock mRNAs during the adaptive process and this binding in turn blocks the transcription of the cold-shock genes or destabilizes their mRNAs. CspA appears to promote either directly or indirectly the repressor function.

Differential expression of cyclooxygenase-1 and -2 proteins in rat uterus and cervix during the estrous cycle, pregnancy, labor and in myometrial cells

The synthesis of prostaglandins in the uterus at term are modulated by two isoforms of the enzyme cyclooxygenase (COX): constitutive COX-1 and inducible COX-2. This study aims to characterize the expression of the protein for COX-1 and -2 in the rat uterus and cervix during the estrous cycle, pregnancy, and labor, and in cultured myometrial cells. Western immunoblotting of proteins was performed and quantitation of protein was obtained densitometrically. Results indicate: 1) the rat uteri, cervix, and isolated myometrial cells express both COX-1 and COX-2 proteins, 2) during pregnancy, both COX-1 and -2 increase, with a dramatic increase at parturition (250%-280%), 3) a 2-fold increase of cervical COX-2 is seen at spontaneous labor, 4) during proestrus and estrus, uterine expression of COX-2 is elevated, 5) both COX-1 and -2 were expressed by rat myometrial cells and treatment with IL-1 beta (10 ng/mL) produced a significant increase in COX-2, and 6) immunocytochemical studies show that both COX-1 and -2 were primarily localized to the epithelial cells of the endometrium and smooth muscle cells in the circular layers of the myometrium in the uterus and to the epithelial cells and smooth muscle cells in the cervix. Thus, we propose that increased expression of COX-2 may be involved at term in increased uterine contractility and cervical ripening.

[Clinical significance of determinations of blood catecholamine, glucose and isulin in burn patients]

Blood catecholamine (CA), glucose and insulin were determined in 30 severe burn patients, of whom 22 were males, and 8 females. Mean burn area was 58.6 percent TBSA. These patients were in hypovolemic shock.

RESULTS

CA release was persistent in severe burn patients showing two peaks in shock period and infection period (P < 0.01). The quantity of epinephrine (E) was normal, while norepinephrine (NE) was presistently high (P < 0.01), and it was over two fold of the normal value. The value seemed to reflect the severity of the injury. When CA did not show a rise in the shock period, or lowered abruptly in the sepsis period, the patients were in high risk. Increasing CA produced increase in gluconeogenesis with insufficiency in SI secretion.

[Analysis of chemokine (S) produced by mouse thymic stromal cell lines]

By using Boyden Chamber and PACS methods, we analysed the chemotactic activity of five mouse thymic stromal cell (MTSC) lines' culture supernatant for neutrophil, monocyte/macrophage and lymphocyte, and the phenotype of the attracted lymphocyes, MTEC 1, MTEC 2, MTEC 3, MTEC 5 are mouse thymus epithelial cell lines. MTDC 4 is a mouse thymus dendritic cell line. The results indicate that all of the five MTSC supernatants have chemotactic activity for the target cells mentioned above but in different degree. Chemokines produced by the MTSC cells can be classified into three categories: (1) Chemokines produced by MTEC 1 and MTEC 2 are more potent for the attraction of neutrophils and lymphocytes. (2) MTDC 4 derived chemokines are highly potent for the attraction of monocytes/macrophages. (3) Chemokines produced by MTEC 3 and MTEC 5 are equally attractive to neutrophils, lymphocytes and monocytes/macrophages. Most of the MTSC-SN are more potent for the migration of B lymphocyte than for T lymphocyte. The MTSC-SN exhibits higher chemotactic activity to CD4-CD8+ T cell subset than to CD4+CD8-T cell subset. The characterization of chemokines in MTSC-SN will benefit the finding of new chemokines and the analysis of the mechanism of thymus homing.

[Hepatitis B virus infection and pathogenesis of glomerulonephritis]

In order to investigate the role of hepatitis B virus (HBV) infection in the pathogenesis of HBV associated glomerulonephritis, 50 cases of glomerulonephritis with positive HBV infection marker antigenemia and/or HBAg detected by immunohistochemistry in renal tissue were collected. The distribution and localization of HBV DNA were observed by using in situ hybridization. In addition, Southern blot analysis was performed in 23 of the 50 cases to reveal the state of renal HBV DNA. Thirty Six cases (72%) were found to be HBV DNA positive by in situ hybridization, which was localized in the nucleus of tubular cells. In 26 cases HBV DNA was simultaneously detected in the nucleus of glomerular mesangial and epithelial cells as well as in the mesangial matrix. Seventeen of the 23 cases proved to be HBV DNA positive by Southern blot analysis. In which 3 cases were identified as having non-replicating free HBV DNA, while 14 cases (82%) were of the integrated form. Since there was abundant evidence of the renal tissue being infected with HBV, it was considered that the HBAg deposited on glomeruli not only originated from circulation but also from the HBV infected glomerular cells. In addition to the humoral immune injury mediated by HBAg-HBAb immune complex, the cellular mechanism mediated by target antigen (HBcAg) may be also involved in the pathogenesis of HBV associated glomerulonephritis.

[A study on the appearance of hepatitis B virus markers in renal tissue of glomerulonephritis]

HBV antigens (HBcAg, HBsAg and HBeAg) in 246 cases of renal biopsy specimens with various types of glomerulonephritis were examined by immunohistochemical techniques. Southern blot hybridization was used to detect HBV DNA in 18 cases. The results showed that HBV antigens were frequently found in the tubular cells in addition to the appearance of HBV antigens on the glomeruli of certain glomerulonephritis. The positive rte of HBcAg in the tubular cells was 21.54%, which is higher than that of glomeruli (10.98%). Renal HBV DNA was positive in 15 cases and among them HBcAg expression in renal tissue in 14 cases and HBV antigenemia in 12 cases. The results suggest that HBV may also be implicated in the pathogenesis of certain cases of glomerulonephritis and the appearance of HBV antigen antibody immunocomplex in renal tissue, aside from originating in the circulation, there is the possibility of it originating from renal cells in situ.

Use of Tl-201 to detect untreated pediatric Hodgkin disease

PURPOSE

To evaluate the usefulness of thallium-201 scintigrams in depiction of supradiaphragmatic lymphadenopathy associated with newly diagnosed Hodgkin disease in pediatric patients.

MATERIALS AND METHODS

Thallium-201 and gallium-67 scans of the chest and neck were obtained in 33 consecutive patients. Mediastinal, cervical, supraclavicular, and axillary lymph node activity was evaluated by independent raters, and results were compared in a blinded fashion with those on chest computed tomographic (CT) scans.

RESULTS

Gallium and thallium scans demonstrated similar accuracy in depiction of CT-defined mediastinal masses. The kappa statistic indicated moderate to strong agreement with CT results. Similarly, there was no statistically significant difference between the accuracy of thallium and gallium scans in depiction of extramediastinal lymphadenopathy.

CONCLUSION

Thallium scintigraphy is effective for depiction of lymphadenopathy in pediatric patients with untreated Hodgkin disease. Serial thallium studies may provide an alternative to gallium scans in monitoring response to treatment.

Assembly of a chromosomal replication machine: two DNA polymerases, a clamp loader, and sliding clamps in one holoenzyme particle. II. Intermediate complex between the clamp loader and its clamp

The Escherichia coli replicase, DNA polymerase III holoenzyme, derives its processivity from the beta subunit sliding clamp that encircles DNA and tethers the replicase to the template. The beta dimer is assembled around DNA by the gamma complex clamp loader in an ATP-dependent reaction. In this report, the essential contact between the clamp loader and beta is identified as mediated through the delta subunit of the gamma complex. The delta subunit appears to contact the face of the beta dimer ring that contains the two C termini. Surprisingly, ATP is required for the gamma complex to bind beta, but not for delta to bind beta. This indicates that delta is buried in the gamma complex and suggests a role for ATP in exposing delta for interaction with beta. A protease protection assay has been developed to specifically probe the delta subunit within the gamma complex. The results of the assay are consistent with an ATP-induced conformational change in the gamma complex that alters the state of the delta subunit within it. The implication of these key features to the clamp loading mechanism of the gamma complex is discussed.

Assembly of a chromosomal replication machine: two DNA polymerases, a clamp loader, and sliding clamps in one holoenzyme particle. I. Organization of the clamp loader

The gamma complex of DNA polymerase III holoenzyme, the replicase of Escherichia coli, couples ATP hydrolysis to the loading of beta sliding clamps onto primed DNA. The beta sliding clamp tethers the holoenzyme replicase to DNA for rapid and processive synthesis. In this report, the gamma complex has been constituted from its five different subunits. Size measurements and subunit stoichiometry studies show a composition of gamma 2 delta 1 delta' 1 1 chi 1 psi 1. Strong intersubunit contacts have been identified by gel filtration, and weaker contacts were identified by surface plasmon resonance measurements. An analogous tau complex has also been constituted and characterized; it is nearly as active as the gamma complex in clamp loading activity, but as shown in the fourth report of this series, it is at a disadvantage in binding the delta, delta', chi, and psi subunits when core is present (Xiao, H., Naktinis, V., and O'Donnell, M. (1995) J. Biol. Chem. 270, 13378-13383). The single copy subunits within the gamma complex provide the basis for the structural asymmetry inherent within DNA polymerase III holoenzyme.

Molecular biology and pharmacology of cloned opioid receptors

The cloning and expression of DNA for the three major opioid receptor types (mu, delta, and kappa) present new research opportunities for the characterization of opioid drugs and their interactions with these receptors. Genomic and cDNA clones for opioid receptors exist for several animal species including mouse, rat, guinea pig, and human. These include clones for all three human opioid receptor types. The receptor proteins consist of about 400 amino acids and have the characteristic seven transmembrane domain structure of G-protein-coupled receptors. There is about 60% amino acid identity between opioid receptor types and about 90% identity between a receptor type cloned from different animal species. All opioid receptor types mediate the inhibition of adenylyl cyclase in response to agonist binding. Radioligand binding and functional studies using the cloned receptors tend to support current conclusions on opioid drug receptor selectivity and activity. Investigations of opioid receptor chimeras and single amino acid mutants are providing information on the ligand recognition sites of these receptors and essential support for the development of computational opioid receptor models. A molecular model of the human delta opioid receptor is included in this review.

Subsequent malignancies in children and adolescents after treatment for Hodgkin's disease

PURPOSE

We assessed the cumulative risk of malignancies following treatment for Hodgkin's disease in childhood and adolescence and investigated related patient and treatment characteristics.

PATIENTS AND METHODS

Medical records of 499 Hodgkin's disease patients treated between 1962 and 1993 were reviewed. There were 385 adolescents (> or = 10 years of age at diagnosis) and 114 preadolescents (< 10 years). Most patients (n = 346) were treated with radiation plus multiagent chemotherapy, while 30 received only chemotherapy and 123 only radiation therapy. Radiation doses ranged from 20 to 42 Gy.

RESULTS

At a median follow-up duration of 9 years (range, 0.1 to 27.4), 25 patients have had second malignancies: 19 solid tumors, four acute nonlymphoblastic leukemias (ANLLs), 1 non-Hodgkin's lymphoma (NHL), and one chronic myeloid leukemia (CML). Three patients have had a third malignancy. The estimated cumulative risk of second malignancies increased from 1.5% at 5 years to 7.7% at 15 years. All but two of the patients with second malignancies were > or = 10 years of age at initial diagnosis, which reflects the higher risk among patients treated for Hodgkin's disease as adolescents (P = .01). Second malignancies were more common among female patients (P = .0002), even when those breast cancer were excluded (P = .007), and in those treated for recurrent Hodgkin's disease (P = .02). Patients with ANLL/NHL were older at diagnosis of Hodgkin's disease than those with solid tumors, (median age, 18.3 v 13.8 years; P = .04). There was no difference between groups treated with radiation therapy alone, chemotherapy alone, or radiation plus multiagent chemotherapy.

CONCLUSION

Adolescents treated for Hodgkin's disease are at greater at risk of second malignancies than younger patients. Overall, adolescent females treated for recurrent Hodgkin's disease appear to be at greatest risk, while preadolescents appear to be protected from this late complication.

Ethnic differences in erythrocyte catechol-O-methyltransferase activity in black and white Americans

Catechol-O-methyltransferase (COMT) catalyzes the O-methylation of catecholamine and catechol drugs such as levodopa and methyldopa. Human COMT activity is inherited as an autosomal co-dominant trait; approximately 25% of white individuals have low activity consistent with homozygosity for a low activity allele, about 50% have intermediate activity (i.e., heterozygous genotype) and 25% have high activity. COMT activity has not been characterized in African-Americans or other black populations. To investigate potential ethnic and gender differences in COMT, we measured erythrocyte COMT activity in 195 unrelated black and 202 unrelated white healthy individuals living in the Southeast United States. Overall, the black population had significantly higher COMT activity than the white population (median 15.7 vs. 11.4 U/ml of packed red blood cell volume; P < .001). Maximum likelihood estimation of COMT activity distribution identified significant ethnic differences, with high activity in 23% of whites and 55% of blacks, intermediate activity in 50% of whites and 38% of blacks and low activity in 27% of whites and 7% of blacks. No greater differences in COMT activity were observed in either ethnic group. We conclude that red blood cell COMT activity is significantly higher in black subjects than white subjects. Hardy-Weinberg estimates indicate that this ethnic difference is due to a higher frequency of high activity COMT alleles in blacks vs. whites (0.74 vs. 0.48).

Amperometric biosensor for phenols based on a tyrosinase-graphite-epoxy biocomposite

A new biocomposite, based on the incorporation of the enzyme tyrosinase into a graphite-epoxy resin matrix, was used for the effective biosensing of phenolic compounds. The enzyme retains its bioactivity on confinement in the epoxy resin environment. This renewable (polishable) and rigid bioprobe offers convenient quantification for various phenolic substrates. The fast response (steady-state time = 25 s) accrues from the close proximity of the enzyme and graphite sites. The influence of various experimental variables was explored for optimum biosensing performance. Flow-injection monitoring of phenolic compounds at a rate of 50 samples h-1 yielded a detection limit of 1 x 10(-6) mol l-1 and a relative standard deviation of 1.4% (n = 40).

Characterization of [3H]naltrindole binding to delta opioid receptors in mouse brain and mouse vas deferens: evidence for delta opioid receptor heterogeneity

Naltrindole (NTI) is a potent and selective nonpeptide delta opioid receptor antagonist. This study reports on the binding characteristics of [3H]NTI (specific activity = 30.5 Ci/mmole) for mouse brain and vas deferens (MVD) tissues. In brain, [3H]NTI had unusually high specific binding to delta receptors (80% at its Kd concentration) relative to other selective delta receptor radioligands. Saturation Kd values with 95% confidence intervals for mouse brain and MVD tissue preparations were 56.2 (41.8-75.7) and 104 (25.8-420) pM, respectively. These Kd values were significantly different (P = .028) and [3H]NTI binding to both tissues was best fit by a one-site model. Receptor densities were 83.9 (66.8-106) fmol/mg of protein for mouse brain and 14.8 (7.03-31.2) fmol/mg of protein for the MVD. Binding inhibition studies showed that NTI and the delta opioid receptor agonists [4'-Cl-Phe4]DPDPE and [D-Ala2, Glu4]deltorphin had high affinity for the sites labeled by [3H]NTI in both tissue preparations whereas mu [Tyr-Pro-psi-MePhe-D-Pro-NH2 (PL-17)] and kappa (U-69593) agonists had micromolar affinity. Both agonists recognized multiple sites in mouse brain under control (with 5 mM Mg++) and treatment (with 50 microM guanylyl-5'-imido-diphosphate and 100 mM NaCl) conditions but only single-site binding was observed for MVD (only control condition tested). [D-Ala2, Glu4]deltorphin showed about 6.5-fold selectivity for a portion (approximately 33%) of mouse brain sites (Ki = 130 pM) compared to sites labeled by [3H]NTI in MVD (Ki = 1200 pM) under control conditions. No significant difference was observed for [4'-Cl-Phe4]DPDPE binding affinity to both tissues (Ki = 450-680 pM) under control conditions. The affinity of opioid agonists, but not antagonists at [3H]NTI binding sites in mouse brain, was substantially reduced by the presence of guanylyl-5'-imidodiphosphate and sodium ions consistent with guanine nucleotide-binding protein regulation of the delta receptors. The portions of high- and low-affinity sites recognized by [4'-Cl-Phe4]DPDPE and [D-Ala2, Glu4]deltorphin in mouse brain labeled by [3H]NTI under treatment conditions were not significantly different (each subtype represented approximately 50% of the total population) suggesting delta receptor heterogeneity in this tissue. It is concluded that [3H]NTI binds to delta opioid receptor affinity states and subtypes with equal affinity and can be used for their characterization in conjunction with different treatment conditions and ligands.

Identification of a human delta opioid receptor: cloning and expression

The delta opioid receptor is an important target for analgesic drug development. This report describes the identification of delta opioid receptor clones from human cDNA libraries and the preparation of a human delta receptor cDNA in the pcDNA3 expression vector for transfection studies. The cDNA encodes a 372 amino acid protein that has 93% amino acid identity to mouse and rat delta receptors. COS-7 cells transfected with this clone express over 1.0 pmol receptor/mg protein when measured by saturation binding with [3H]naltrindole. The delta receptor selective ligands NTB, BNTX, [4'-Cl-Phe4]DPDPE and [D-Ala2,Glu4]deltorphin all have Ki values under 10 nM while the affinities of the mu and kappa opioid receptor ligands CTAP and U-69593, respectively, are over 4.0 microM. Agonists show binding to multiple affinity states of the receptor consistent with the presence of G-protein coupled and uncoupled forms of the expressed receptor. The 8-fold higher affinity of NTB relative to BNTX suggests that the human delta receptor is of the delta 2 subtype.

Effect of the relative position of the UGA codon to the unique secondary structure in the fdhF mRNA on its decoding by selenocysteinyl tRNA in Escherichia coli

The fdhF mRNA for formate dehydrogenase H of Escherichia coli contains a UGA codon at position 140. This termination codon is decoded by selenocysteinyl tRNA (the selC product) with the aid of its own specific elongation factor, SelB. For this decoding, a unique secondary structure immediately downstream of the UGA codon has been shown to be essential (Zinoni, F., Heider, J., and Böck, A. (1990) Proc. Natl. Acad. Sci. U. S. A. 87, 4660-4664). We examined the positional effect of the UGA codon relative to the secondary structure on its decoding using a fdhF-lacZ fusion gene. When the UGA codon was separated by one codon (position -1) from the secondary structure, the UGA decoding, as measured by the beta-galactosidase activity, dropped to approximately 76% of the normal level but was still almost as fully dependent upon selC and selenium in the culture medium as in the case of the UGA codon in the normal position (position 0). However, when the UGA codon was separated by two codons (position -2), the decoding level further dropped to 20% of the normal level, and in addition, became dependent only on selC but independent of selenium. When the UGA codon was further separated by three codons (position -3), the decoding level of UGA (-3) became higher than the decoding of UGA (-2) and was completely independent from selC and selenium, indicating that the UGA codon was nonspecifically suppressed. A similar nonspecific suppression was observed for the UGA codon at position -4, but at a lower level. When two UGA codons were tandemly placed at positions 0 and -1, they were still able to be decoded at 17% of the normal level in a selC- and selenium-dependent manner. In the absence of the SelB function, the decoding level of UGA(0) dropped to 1.6% of the normal level, whereas the UGA(-1) decoding dropped to 7.5%. These results indicate that the UGA codon at position 0 is not only most effectively decoded by selenocysteinyl tRNA but also tightly blocked from its nonspecific suppression in the absence of any components required for the decoding.

Characterization of the molecularly cloned murine alpha-globin transcription factor CP2

We recently cloned human and murine cDNAs that encode CP2, a transcription factor that interacts with the murine alpha-globin promoter. In this report, we exploited our ability to express CP2 in bacteria and eukaryotic cells to further investigate factor activities in vitro and in vivo. CP2 expressed in bacteria was significantly enriched and used in a series of DNase I footprinting and electrophoretic gel shift assays. The results suggest that CP2 binds a hyphenated recognition sequence motif that spans one DNA helix turn. In addition, the enriched bacterial protein activated transcription of alpha-globin promoter templates approximately 3- to 4-fold in vitro. We then tested the effect of elevating CP2 levels 2.5- to 5.5-fold in vivo using both transient and stable transformation assays. When a reporter construct comprised of the intact murine alpha-globin promoter driving the bacterial chloramphenicol acetyltransferase (CAT) gene was introduced into these overexpressing cells, we observed a 3- to 6-fold increase in CAT activity when compared to cells expressing normal levels of CP2. These results define the CP2 factor binding site in more detail and help characterize the activities of the factor in vivo.

Binding of BW 373U86, a non-peptidic delta opioid receptor agonist, is not regulated by guanine nucleotides and sodium

BW 373U86 is a novel, non-peptidic delta-opioid receptor ligand with agonist properties in mouse brain and in the mouse isolated vas deferens. The sensitivity of BW 373U86, and of the peptide delta-opioid agonists [D-Pen2,D-Pen5]enkephalin (DPDPE) and [D-Ala2,Glu4]deltorphin, to regulation by guanine nucleotides and sodium was evaluated in competition studies against the 5 selective radioligand [3H]naltrindole. The IC50 values for DPDPE and [D-Ala2,Glu4]deltorphin were significantly increased in brain and mouse vas deferens in the presence of Gpp(NH)p and NaCl. In contrast, the IC50 values for BW 373U86 were not altered in the presence of Gpp(NH)p and NaCl in either tissue. The data indicate that the agonist properties of BW 373U86 may not be affected by the supposed uncoupling of the alpha-subunit of the G-protein from a receptor thought to be G-protein linked.

Isolation and characterization of cDNAs encoding wheat 3-hydroxy-3-methylglutaryl coenzyme A reductase

The enzyme 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGR, EC 1.1.1.34) is a key enzyme in the isoprenoid biosynthetic pathway. We have isolated partial cDNAs from wheat (Triticum aestivum) using the polymerase chain reaction. Comparison of deduced amino acid sequences of these cDNAs shows that they represent a small family of genes that share a high degree of sequence homology among themselves as well as among genes from other organisms including tomato, Arabidopsis, hamster, human, Drosophila, and yeast. Southern blot analysis reveals the presence of at least four genes. Our results concerning the tissue-specific expression as well as developmental regulation of these HMGR cDNAs highlight the important role of this enzyme in the growth and development of wheat.

Unexpected antinociceptive potency of cyclic [D-Tca1]CTAP: potential for a novel mechanism of action

This study tested the hypothesis that compounds which may bind simultaneously to delta and mu receptors may be more potent antinociceptive agents than would be predicted from their binding affinities at individual mu and delta opioid receptors. D-Tca-Cys-Tyr-D-Trp-Arg-Thr-Pen-Thr-NH2 ([D-Tca1]CTAP) (where D-Tca is a cyclic D-tryptophan analogue) was synthesized and evaluated in radioligand competition assays, opioid bioassays, and in an antinociceptive assay (the tail-flick test in mice). Additionally, the metabolic stability of [D-Tca1]CTAP was evaluated in striatal and cerebellar tissue slices. In rat brain in vitro, [D-Tca1]CTAP competed weakly for sites labelled by [3H]D-Phe-Cys-Tyr-D-Trp-Om-Thr-Pen-Thr-NH2 ([3H]CTOP) (mu-ligand), and [3H][D-Pen2,pCl-Phe4,D-Pen5]enkephalin (delta-ligand); [D-Pen2,D-Pen5]enkephalin (DPDPE) (delta-agonist) was 6.5-fold less and 230-fold more potent, respectively, against these ligands. Additionally, in mouse isolated vas deferens and guinea pig isolated ileum smooth muscle preparations, [D-Tca1]CTAP proved to be weak as either a delta (IC50 of approximately 2 microM) or mu (IC50 > 8 microM) receptor agonist. Surprisingly, however, i.c.v. [D-Tca1]CTAP produced antinociception with potency similar to DPDPE. The antinociceptive actions of [D-Tca1]CTAP were apparently not due to a metabolite or the release of endogenous opioids, as this compound proved stable in both striatal and cerebellar tissue slices and its antinociceptive actions were not enhanced by the 'enkephalinase' inhibitor thiorphan. The suggestion that [D-Tca1]CTAP might be acting by binding simultaneously to mu and delta receptors to produce its antinociceptive effect is supported by the demonstrated antagonism resulting from mu receptor blockade with either beta-funaltrexamine (beta-FNA) or naloxonazine, or by delta receptor blockade by ICI 174,864 ([N,N-diallyl-Tyr1,Aib2,3,Leu5] enkephalin). Furthermore, the antinociceptive properties of [D-Tca1]CTAP were antagonized by (naltrindole-5'-isothiocyanate) (5'-NTII), an antagonist at the delta 2 opioid receptor subtype, but not by the delta 1 antagonist [D-Ala2,D-Leu5,Cys6]enkephalin (DALCE). Additionally, no antagonism was produced by nor-binaltorphimine (nor-BNI), a kappa antagonist. From these data, [D-Tca1]CTAP appears to bind to mu, and 5'-NTII-sensitive delta 2, opioid receptors, and may represent the first of a class of compounds which may act at an opioid receptor complex via 'self-potentiation'.

Ring substituted and other conformationally constrained tyrosine analogues of [D-Pen2,D-Pen5]enkephalin with delta opioid receptor selectivity

The conformationally restricted, cyclic disulfide-containing delta opioid receptor selective enkephalin analogue [D-Pen2,D-Pen5] enkephalin (DPDPE) was modified by 2' (CH3) and 3' (I, OCH3, NO2, NH2) ring substitutions and by beta-methyl conformationally constrained beta-methyltyrosine derivatives in the 1 position. The potency and selectivity of these analogues were evaluated by bioassay in the mouse vas deference (MVD, delta receptor assay) and guinea pig ileum (GPI, mu receptor assay) assays and by radioreceptor binding assays in the rat brain using [3H]CTOP (mu ligand) and [3H][p-ClPhe4]DPDPE (delta ligand). The analogues showed highly variable potencies in the binding assays and in the bioassays. Aromatic ring substituents with positive Hammett constants had decreased potency, while substituents with negative Hammett constraints has increased potency for the opioid receptor. The most potent and most selective compound based on the binding was [2'-MeTyr1]DPDPE (IC50 = 0.89 nM and selectivity ratio 1310 in the binding assays). The 6-hydroxy-2-aminotetralin-2-carboxylic acid-containing analogue, [Hat1]DPDPE, also was highly potent and selective in both assays, demonstrating that significant modifications of tyrosine in enkephalins are possible with maintenance of high potency and delta opioid receptor selectivity. Of the beta-methyl-substituted Tyr1 analogues, [(2S,3R)-beta-MeTyr1]DPDPE was the most potent and the delta receptor selective. The results with substitution of beta-MeTyr or Hat instead of Tyr also demonstrate that topographical modification in a conformationally restricted ligand can significantly modulate both potency and receptor selectivity of peptide ligands that have multiple sites of biological activity.