A new strategy for the application of CA19-9 in the differentiation of pancreaticobiliary cancer: analysis using a receiver operating characteristic curve

OBJECTIVE

Clinicians might be misled in interpreting an elevated CA19-9 when differentiating pancreaticobiliary cancer from benign clinical conditions such as acute cholangitis or cholestasis, because in these conditions, the concentration of CA19-9 may also be elevated. The aims of our study were to calculate new individual cutoff values for CA19-9 according to clinical situations using a receiver operating characteristic (ROC) curve and to define a new strategy for interpreting CA19-9 in pancreaticobiliary cancer.

METHODS

One hundred sixty patients with pancreatic diseases (cancer 90, benign disease 70), 322 patients with biliary tract diseases (biliary cancer 152, benign disease 170), and 20,035 asymptomatic controls were enrolled in the present study. An ROC curve was described by plotting the sensitivity on the y-axis against 1-specificity on the x-axis for each of several cutoff values.

RESULTS

The area under the ROC curve was significantly greater for pancreatic cancer than for biliary cancer (p < 0.05). For patients with pancreatic cancer, CA19-9 proved to be useful. At a cutoff value of 37 U/ml, sensitivity and specificity were 76.7% and 87.1%, respectively. For patients with biliary cancer, CA19-9 was not helpful. However, when patients with biliary disease were divided into two groups according to the presence of cholangitis or cholestasis, CA19-9 proved to be more useful for the group without cholangitis or cholestasis than for the group with cholangitis or cholestasis (p < 0.05). In the former group, the sensitivity and specificity of CA19-9 were 77.6% and 83%, respectively, at the cutoff value of 37 U/ml. For the latter group, the sensitivity and specificity of CA19-9 were 74% and 41.5% respectively, whereas the specificity reached 87% at 300 U/ml. CA19-9 in diagnosing pancreatic cancer was useful regardless of accompanying acute pancreatitis or cholestasis. The serum concentration of CA19-9 in asymptomatic individuals was 9.42 +/- 9.95 U/ml. Only 1 of 157 patients with a concentration of CA19-9 above 37 U/ml was found to have gallbladder cancer. The positive and negative predictive values were 0.65% and 0.78%, respectively.

CONCLUSIONS

The use of CA19-9 for the differentiation of pancreaticobiliary cancer should be applied individually, depending on the clinical situation.

Choledochal cyst associated the with anomalous union of pancreaticobiliary duct (AUPBD) has a more grave clinical course than choledochal cyst alone

OBJECTIVE

Since choledochal cyst is frequently associated with the anomalous union of pancreaticobiliary duct (AUPBD), AUPBD has been regarded to be the etiologic factor of choledochal cyst. However, the clinical significance of AUPBD an patients with choledochal cyst has not been clearly defined. Therefore, to clarify the significance of AUPBD in choledochal cyst patients, we compared the clinical features of patients with choledochal cyst according to the presence or absence of AUPBD.

METHODS

Among 52 cases which were diagnosed as choledochal cyst out of 5,037 ERCP referrals between August 1990 and December 1996, we selected 44 cases, in which the pancreaticobiliary junction was clearly visualized on cholangio-pancreaticography. These cases were divided into AUPBD-present group (n = 28) and AUPBD-absent group (n = 16). Clinical features were compared between the two groups. Furthermore, in AUPBD-present group, clinical data were also analyzed according to Kimura's classification of AUPBD.

RESULTS

In our study, AUPBD was associated with choledochal cyst in 28 (64%) cases. AUPBD was found only in type I and IV according to Todani's classification of choledochal cyst. There were no significant differences between the AUPBD-present group and the AUPBD-absent group in the incidence of gallstone disease, while the incidence of acute inflammation was 93% (26/28) in the AUPBD-absent group (p < 0.01). Carcinoma developed only in the AUOBD-present group (9/28, 32%) (p < 0.05). Pancreatic disorders (i.e. pancreatic stone, pancreatitis or pancreatic cancer) occurred in 12 of 28 cases in the AUPBD-present group (43%), while only in 1 of 16 cases in the AUPBD-absent group (6%) (p < 0.05).

CONCLUSION

AUPBD associated with choledochal cyst may have implications not only as a possible etiologic factor but also as an important factor that may affect the clinical course, surgical planning and prognosis. In cases with choledochal cyst, we should make an effort to evaluate the presence of AUPBD.

Development of dried liposomes containing beta-galactosidase for the digestion of lactose in milk

The hydrolyzed-lactose milk for lactase-deficient subjects has a sweeter taste than whole milk, and some subjects dislike its taste. In order to cope with this shortcoming, we examined whether beta-galactosidase, which hydrolyzes lactose, added to the whole milk in the form of dried liposomes, would be able to digest lactose in milk following the lysis of liposomes in the presence of bile salts. Dried liposomes containing beta-galactosidase were prepared in the presence of trehalose by the dehydration-rehydration vesicle method to overcome the instability of the conventional liposome suspension. The stability of liposomal membranes was evaluated by measuring the activity of entrapped beta-galactosidase under various storage conditions. By treating liposomes with trehalose, which was found to prevent the fusion of liposomes and the leakage of entrapped drug, the entrapping efficiency increased up to fourfold. Over 95% of dried liposomes which had been stored at 17 degrees C for 60 days were reconstituted to liposomes upon rehydration process. From the stability study, dried liposomes were found to retain 87% of beta-galactosidase activity at 17 degrees C after 60 days and to be more stable than the multilamellar vesicle suspension prepared without trehalose. The lysis study showed that dried liposomes were hardly lyzed in the simulated gastric fluid with pepsin, but lyzed immediately more than 90% in 0.01 M deoxycholic acid. Lactose hydrolysis in the presence of deoxycholic acid after the addition of dried liposome-entrapped beta-galactosidase to whole milk was proportional to the quantity of entrapped beta-galactosidase and the amount of dried liposomes added. These results demonstrate that beta-galactosidase entrapped in liposome is stable and reconstituted mostly upon rehydration, and can digest lactose in milk after the efficient lysis of liposomes in the presence of bile salts. This study implies that beta-galactosidase entrapped in liposome may be applied to whole milk for lactase-deficient subjects.

Target temperatures of 48 degrees C versus 60 degrees C during slow pathway ablation: a randomized comparison

INTRODUCTION

The relationship between temperature at the electrode-tissue interface and the loss of AV and ventriculoatrial (VA) conduction is not established, and the optimal target temperature for the slow pathway approach to radiofrequency ablation of AV nodal reentrant tachycardia (AVNRT) is unknown. Therefore, the purpose of this study was to compare target temperatures of 48 degrees C and 60 degrees C during the slow pathway approach to ablation of AVNRT.

METHODS AND RESULTS

The study included 138 patients undergoing ablation for AVNRT. Patients undergoing slow pathway ablation using closed-loop temperature monitoring were randomly assigned to a target temperature of either 48 degrees C or 60 degrees C. The primary success rates were 76% in the patients assigned to 48 degrees C and 100% in the patients assigned to 60 degrees C (P < 0.01). The ablation procedure duration (33 +/- 31 min vs 26 +/- 28 min; P = 0.2), fluoroscopic time (25 +/- 15 min vs 24 +/- 16 min; P = 0.5), and mean number of applications (9.3 +/- 6.5 vs 7.8 +/- 8.1; P = 0.3) were similar in patients assigned to 48 degrees and 60 degrees C, respectively. The mean temperature (46.1 degrees +/- 24.8 degrees C vs 48.7 +/- 3.2 degrees C; P < 0.01), the temperature associated with junctional ectopy (48.1 degrees +/- 2.0 degrees C vs 53.5 degrees +/- 3.5 degrees C, P < 0.0001), and the frequency of VA block during junctional ectopy (24.6% vs 37.2%; P < 0.0001) were less in the patients assigned to 48 degrees C compared to 60 degrees C. The frequency of transient or permanent AV block was similar in each group (2.8% vs 3.6%; P = 0.2). In the 60 degrees C group, only 12% of applications achieved an electrode temperature of 60 degrees C. During follow-up of 9.9 +/- 4.2 months, there was one recurrence of AVNRT in the 48 degrees C group and none in the 60 degrees C group.

CONCLUSIONS

Compared to 48 degrees C, a target temperature of 60 degrees C during radiofrequency slow pathway ablation is associated with a higher primary success rate and a higher incidence of VA block during junctional ectopy induced by the radiofrequency energy. AV block is not more common with the higher target temperature, but only if VA conduction is aggressively monitored during applications of radiofrequency energy.

An 86 kDa diapause protein 1-like protein is a component of early-staged encapsulation-relating proteins in coleopteran insect, Tenebrio molitor larvae

Recently, we reported two novel early-staged encapsulation-relating proteins (56 kDa and 48 kDa ERPs) isolated from the hemolymph of coleopteran insect, Tenebrio molitor larvae [Cho et al. (1999) Eur. J. Biochem. (in press)]. Here, a cDNA clone for another early-staged encapsulation-relating protein (86 kDa) was isolated. We found that the 86 kDa protein shows high homology with insect diapause protein 1. The 86 kDa protein was localized in the fat body and hemolymph, but not hemocyte lysate. A significant level of 86 kDa protein was detected in pre-pupae stage, but it decreased rapidly at late larvae and pupae, and no protein was found in embryo, early larvae and adult stages. This diapause protein 1-like protein is likely to be a component of early-staged encapsulation-relating proteins in the insect cellular defense reaction.

Inflammatory pseudotumor of the liver in patients with recurrent pyogenic cholangitis: CT-histopathologic correlation

PURPOSE

To correlate computed tomographic (CT) features of inflammatory pseudotumors of the liver with histopathologic results in patients with recurrent pyogenic cholangitis.

MATERIALS AND METHODS

CT features of 13 cases of inflammatory hepatic pseudotumor in 10 patients with recurrent pyogenic cholangitis were reviewed. Diagnosis was made by means of surgical resection in all patients. CT scans were analyzed for the appearance of masses and ancillary findings in correlation with the histopathologic findings in each resected specimen.

RESULTS

The masses were 2.0-7.0 cm (mean, 3.5 cm). At nonenhanced CT, the masses appeared as ill-defined, hypoattenuating lesions. At contrast material-enhanced CT, the masses exhibited central hypoattenuating areas with an iso- or hyperattenuating thickened periphery in four cases and a multiseptate appearance with hyperattenuating internal septa and periphery in nine cases. CT-histopathologic correlation showed that the central hypoattenuating area indicated the presence of chronic inflammatory infiltrates with foamy histiocytes, plasmacytes, and lymphocytes, while iso- or hyperattenuating areas in the periphery and internal septa of the mass represented fibroblastic proliferation. All patients had CT features of recurrent pyogenic cholangitis, such as hepatolithiasis, intrahepatic duct stricture and dilatation, common bile duct calculi, pneumobilia, or parenchymal atrophy.

CONCLUSION

Although CT features are not specific, inflammatory pseudotumor should be included in the differential diagnosis in patients with recurrent pyogenic cholangitis and a hepatic mass detected at CT.

Intraspinal epidermoid cyst occurring 15 years after lipomyelomeningocele repair. Case report

The authors report the case of a spinal epidermoid cyst that developed in a patient who had undergone surgery for lipomyelomeningocele repair 15 years earlier. The patient presented with symptoms of retethering. Magnetic resonance imaging revealed a cystic intraspinal mass that extended from L-2 to L-5. The mass proved to be an epidermoid cyst. Spinal epidermoid cysts can cause retethering after a repair of lipomyelomeningocele, and the risk of this development can be present for decades.

Molecular genetic analysis of the DiGeorge syndrome among Korean patients with congenital heart disease

The DiGeorge syndrome (DGS) is a developmental defect of the third and fourth pharyngeal pouches, which is associated with congenital heart defects, hypoparathyroidism, cell-mediated immunodeficiency, velo-pharyngeal insufficiency and craniofacial dysmorphism. The aetiological factor in a great majority of DGS cases is monosomy for the chromosomal region 22q11. To analyze DGS at the molecular level, a new molecular probe (DGCR680) encompassing the ADU balanced translocation breakpoint was prepared. When 13 Korean patients with DGS-type congenital heart disease were analyzed with this probe, 9 turned out to have a deletion at this locus, and all of them except one exhibited a typical facial dysmorphism associated DGS. Though only 9 independent patients were detected to have a deletion at the locus using the commercial probe N25 (D22S75), which maps at about 160 kb from the ADU breakpoint to the telomeric end, results from fluorescence in situ hybridization revealed a deletion in all cases tested at this locus. Two patients who had a deletion at the locus D22S75 but not at DGCR680 did not exhibit any DGS-type facial abnormalities. This result implies that the 680 bp probe covering the ADU translocation breakpoint might be a candidate for a molecular marker that can distinguish a specific phenotype, such as facial features associated with the DiGeorge syndrome. This study also suggested that systematic approaches with several small DNA probes along the DGCR could help to dissect the complex phenotypes associated with the DiGeorge syndrome, such as cardiac defects, abnormal faces, thymic hypoplasia, cleft palate, and hypocalcemia, etc.

Usefulness of cholangioscopy in patients with focal stricture of the intrahepatic duct unrelated to intrahepatic stones

BACKGROUND

Intrahepatic duct strictures are usually caused by intrahepatic duct stones and cholangitis. However, focal strictures of the intrahepatic duct unrelated to intrahepatic stones often pose diagnostic problems. This study was undertaken to prospectively evaluate the usefulness of percutaneous transhepatic cholangioscopy in patients with focal intrahepatic duct stricture and no evidence of a stone.

METHODS

Seventeen patients with focal strictures of the intrahepatic duct without any evidence of a stone were included. Percutaneous transhepatic cholangioscopic examination including procurement of biopsy specimens was performed after percutaneous transhepatic biliary drainage.

RESULTS

A histopathologic diagnosis was obtained in all patients (9 adenocarcinomas, 1 squamous cell carcinoma, 2 hepatocellular carcinomas, 2 adenomas, and 3 benign strictures). Of the 9 patients with bile duct adenocarcinoma, 8 underwent surgery and a curative resection was possible in 7 patients (88%). Five patients (63%) had early-stage bile duct cancer in which cancer invasion was limited to the mucosa or fibromuscular layer and there was no evidence of lymph node metastasis.

CONCLUSIONS

Percutaneous transhepatic cholangioscopy in patients with focal stricture of the intrahepatic duct unrelated to choledocholithiasis is useful for diagnosis including the detection of early bile duct cancer.

Mutational analysis of aspartate residues in the transmembrane regions and cytoplasmic loops of rat vesicular acetylcholine transporter

The vesicular acetylcholine transporter (VAChT) is responsible for the transport of the neurotransmitter acetylcholine (ACh) into synaptic vesicles using an electrochemical gradient to drive transport. Rat VAChT has a number of aspartate residues within its predicted transmembrane domains (TM) and cytoplasmic loops, which may play important structural or functional roles in acetylcholine transport. In order to identify functional charged residues, site-directed mutagenesis of rVAChT was undertaken. No effect on ACh transport was observed when any of the five aspartate residues in the cytoplasmic loop were converted to asparagine. Similarly, changing Asp-46 (D46N) in TM1 or Asp-255 (D255N) in TM6 had no effect on ACh transport or vesamicol binding. However, replacement of Asp-398 in TM10 with Asn completely eliminated both ACh transport and vesamicol binding. The conservative mutant D398E retained transport activity, but not vesamicol binding, suggesting this residue is critical for transport. Mutation of Asp-193 in TM4 did not affect ACh transport activity; however, vesamicol binding was dramatically reduced. With mutant D425N of TM11 transport activity for ACh was completely blocked, without an effect on vesamicol binding. Activity was not restored in the conservative mutant D425E, suggesting the side chain as well as the negative charge of Asp-425 is important for substrate binding. These mutants, as well as mutant D193N, clearly dissociated ACh binding and transport from vesamicol binding. These data suggest that Asp-398 in TM10 and Asp-425 in TM11 are important for ACh binding and transport, while Asp-193 and Asp-398 in TM4 and TM10, respectively, are involved in vesamicol binding.

Effects of ovarian source, patient age, and menstrual cycle phase on in vitro maturation of immature human oocytes

OBJECTIVE

To determine the efficiency of in vitro maturation, expressed by nuclear maturation, of oocytes aspirated during gynecologic surgeries or collected from excised ovaries. To assess the effect of patient age and cycle phase at collection on the oocyte's ability to mature in vitro. To examine the time course of oocyte maturation in vitro.

DESIGN

Nuclear maturation based on patient criteria compared.

SETTING

University-based IVF program and research center.

PATIENT(S)

Consented patients undergoing gynecologic surgeries or patients undergoing oophorectomy.

INTERVENTION(S)

Oocytes were maintained in culture for 48 hours and evaluated for maturation.

MAIN OUTCOME MEASURE(S)

Nuclear maturation evaluated as germinal vesicle breakdown (GVBD) or progression to the metaphase II (MII) stage.

RESULT(S)

A significantly higher percentage of oocytes collected during the follicular phase of the menstrual cycle underwent GVBD than did oocytes collected during the luteal phase (60% versus 48%, respectively). The percentage of oocytes reaching the MII stage, from these two groups, was not different. No statistically significant differences in maturation were observed in oocytes from different ovarian sources or from patients >40 or <40 years of age.

CONCLUSION(S)

These data suggest that oocytes collected during the follicular phase are more likely to undergo GVBD than oocytes collected during the luteal phase. In this study, ovarian source, age, or cycle phase did not influence the final meiotic maturation of oocytes to metaphase II.

Cerebral vasoreactivity by transcranial Doppler in carbon disulfide poisoning cases in Korea

The abnormalities of cerebral vasoreactivity were evaluated in CS2 poisoning cases. In 34 retired workers with CS2 poisoning (case group) and 20 healthy individuals (control group), blood flow velocities were measured in the middle cerebral arteries (MCA) by transcranial Doppler. Compared with the control group, the case group showed lower mean values of blood flow velocities and pulsatile indices. The differences in CO2 reactivities of both groups were remarkable (1.10-2.19% decrease/mmHg CO2 for cases and 3.35-5.08 for controls). Multiple regression analyses were conducted to adjust the effect of age, sex, and exposure level (non-low-high exposure) to CO2 reactivity and pulsatile index. The exposure level was statistically significant in the regression model for CO2 reactivity of both MCA and for pulsatile index of the right MCA. Our study noted a decrease of CO2 reactivity and pulsatile index of cerebral vessels related with CS2 exposure. These findings suggested that CS2 exposure could lead to a decrease of cerebral vasoreactivities by the atherosclerotic change of cerebral vessels.

Activin A stimulates meiotic maturation of human oocytes and modulates granulosa cell steroidogenesis in vitro

OBJECTIVE

To test the hypothesis that activin A promotes in vitro human oocyte meiotic maturation while inhibiting steroid secretion by nonluteinized antral granulosa cells.

DESIGN

Prospective randomized controlled study.

SETTING

A university medical center.

PATIENT(S)

Nine women ranging in age from 31-44 years who were undergoing oophorectomy for nonovarian pathology.

INTERVENTION(S)

Analysis of meiotic maturation of oocytes and steroid secretion by granulosa cells cultured in the presence or absence of activin A.

MAIN OUTCOME MEASURE(S)

Germinal vesicle breakdown (GVBD) and attainment of metaphase II (MII) in oocytes, and progesterone and E2 secretion by granulosa cells.

RESULT(S)

Activin A significantly enhanced GVBD (91% vs. 65%) for control and maturation to MII (56% vs. 35% for control) of immature oocytes. Activin A significantly suppressed basal, and inhibin A-and FSH-stimulated progesterone and E2 secretion by nonluteinized granulosa cells.

CONCLUSION(S)

Activin A is a promoter of oocyte maturation in vitro and a modulator of granulosa cell steroidogenesis in culture.

MR cholangiopancreatography of pancreaticobiliary diseases: comparing single-shot RARE and multislice HASTE sequences

OBJECTIVE

In this study, we compared the single-shot rapid acquisition with relaxation enhancement (RARE) sequence with the multislice half-Fourier acquisition single-shot turbo spin-echo (HASTE) sequence to assess the ability of each technique to show various pancreaticobiliary diseases using MR cholangiopancreatography.

SUBJECTS AND METHODS

MR cholangiopancreatography was performed using both the single-shot RARE and the multislice HASTE pulse sequences in 80 consecutive subjects in whom we had proof of a range of diagnoses. The study population included healthy subjects (n = 9), patients with benign lesions (n = 41), and patients with malignant lesions (n = 30). We analyzed each image using the following criteria: the cause of the lesions, the image quality (i.e., the amount of artifact and the sharpness of anatomic structures such as the right and left hepatic ducts, the extrahepatic bile duct, and the main pancreatic duct), and the reviewers' preference of images. The images were evaluated independently by two radiologists who were unaware of the results of the other cholangiopancreatographic sequence and of the diagnosis.

RESULTS

Artifacts were less prominent in images that were obtained using the single-shot RARE sequence (p = .0192); however, the sharpness of anatomic structures was the same using either sequence (p = .1673). For images that were obtained using the single-shot RARE technique, the sensitivity, specificity, and accuracy in distinguishing malignant from other abnormalities were 83%, 78%, and 80%, respectively; for the multislice HASTE technique, these values were 77%, 72%, and 74%, respectively (p > .05). Disease-specific accuracy in determining the correct diagnosis was 54% and 59%, respectively (p > .05). In patients in whom all the ducts needed to be defined, the single-shot RARE technique was preferred to the multislice HASTE technique (p < .01).

CONCLUSION

The single-shot RARE technique shows fewer artifacts and is preferred to the multislice HASTE technique. However, both techniques show the same degree of sharpness of anatomic structures, both are able to reveal malignant diseases, and both provide enough information to determine a specific diagnosis.

Pharmacokinetics of propentofylline and the quantitation of its metabolite hydroxypropentofylline in human volunteers

Propentofylline (PPF, 3-methyl-1-(5-oxohexyl)-7-propylxanthine) has been reported to be effective for the treatment of both vascular dementia and dementia of the Alzheimer type. The pharmacological effects of PPF may be exerted via the stimulation of nerve growth factor, increased cerebral blood flow, and inhibition of adenosine uptake. The objectives of this experiment are to determine the kinetic behavior of PPF, to identify, and to quantify its metabolite in human. Blood samples were obtained from human volunteers following oral administration of 200 mg of PPF tablets. For the identification and quantification of the metabolite, 3-methyl-1-(5-hydroxyhexyl)-7-propylxanthine (PPFOH), PPFOH was synthesized and identified by gas chromatography/mass spectroscopy (GC/MS) and 1H-nuclear magnetic resonance spectroscopy. The molecular weight of synthesized metabolite is 308 dalton. The PPF and PPFOH in plasma were extracted with diethyl ether and identified by electron impact GC/MS. The plasma concentrations of PPF and PPFOH were determined by gas chromatography/nitrogen phosphorus detector in plasma and their pharmacokinetic parameters were determined. The mean half-life of PPF was 0.74 hr. The areas under the curve (AUCs) of PPF and PPFOH were 508 and 460 ng.hr/ml, respectively. Cmax of PPF was about 828.4 ng/ml and the peak concentration was achieved at about 2.2 hr (Tmax). These results indicate that PPF is rapidly disappeared from blood due to extensive metabolism into PPFOH.

Biliary papillomatosis: clinical, cholangiographic and cholangioscopic findings

BACKGROUND AND STUDY AIMS

Biliary papillomatosis (BP) is a very rare disease and its clinical features and outcome are not well known. The aims of this study were to describe the characteristic cholangiographic findings and to define the role of cholangioscopic examination in the diagnosis and treatment of this disorder.

PATIENTS AND METHODS

Nine patients (six men and three women, mean age 57 years) were diagnosed as BP among 5361 cases of endoscopic retrograde cholangiography (ERC) from 1990 to 1997 in our institution. The cholangiographic and cholangioscopic findings as well as clinical features were retrospectively analyzed.

RESULTS

ERC findings showed multiple small, round-to-ovoid filling defects in the bile duct and ductal wall irregularity in all the patients. Seven out of nine patients underwent percutaneous transhepatic cholangioscopic (PTC) examination. Additional small papillary lesions in the intrahepatic bile duct were detected by cholangioscopic examination in four patients whose ERC findings only revealed the extrahepatic lesions. Two of these four patients underwent curative resection. In these two patients, the initial surgical plan was changed from Whipple's operation to hepatico-pancratico-duodenectomy after preoperative cholangioscopic examination due to the detection of new lesions in the intrahepatic bile duct.

CONCLUSIONS

ERC findings of BP were highly characteristic. When BP is suspected by conventional imaging including ERC, preoperative percutaneous transhepatic cholangioscopic examination is, however, strongly recommended. This procedure may be beneficial to precisely determine the ductal extension of the disease, hence to decide whether or not hepatic resection is needed as well as to confirm the histology.

Sequence analysis of the 5'-flanking region of the gene encoding human HOXA-7

We have isolated and characterized the immediate 5'-flanking region (886 bp) of the gene encoding human HOXA-7. When the total sequence was compared with those of mice, 93% of the 3' 518 bp (nt 370-886) sequences were identical, in which the 245 bases just preceding the AUG initiator codon (nt 614) was as highly conserved as in the coding region (nt 614-886). Sequences further upstream (nt 1-370) by comparison were highly diverged. In the 245 bp region, 8 stop and 3 initiation (including the initiator) codons were located, and a 50-aa long presumptive polypeptide was encoded. Nucleotide sequence analysis revealed three Sp1 and one AP2 binding sites, as well as one CAAT box. However, there was no consensus sequence for a TATA box in the 5' flanking region. One RARE repeat, one krox20 and three Hox-PBC binding sites were detected. Since many of the factor recognition sites were located in the immediate 5' flanking sequences of a highly-conserved region, it might be speculated that a regulatory mechanism for Hox gene expression is conserved throughout the evolution and one possible mechanism could be at the post-translational level.

Inhibitory effect of calyculin A, a Ser/Thr protein phosphatase type I inhibitor, on renin secretion

We have recently shown that several putative selective inhibitors of Ca2+-calmodulin-dependent myosin light chain kinase (MLCK), such as ML-9 [1-(5-chloronaphthalene-1-sulfonyl)-1H-hexahydro-1,4-diazepine], reversibly stimulate renin secretion [C. S. Park, S.-H. Chang, H. S. Lee, S.-H. Kim, J. W. Chang, and C. D. Hong. Am. J. Physiol. 271 (Cell Physiol. 40): C242-C247, 1996]. We hypothesized that Ca2+ inhibits renin secretion, via phosphorylation of 20-kDa myosin light chain (MLC20), by activating MLCK. In the present studies, we have investigated the types of protein phosphatase (PP) involved in the control of renin secretion through inhibition of MLC dephosphorylation using inhibitors of various types of serine/threonine-specific protein phosphatases. Cyclosporin A, a putative inhibitor of PP type 2 (calcineurin), was without effect. Calyculin A and okadaic acid, putative selective inhibitors of both PP type 1 (PP1) and type 2A (PP2A), significantly inhibited renin secretion under control conditions. Calyculin A had inhibitory effects at least 10-fold more potent than okadaic acid, suggesting that PP1, rather than PP2A, is involved in the control of renin secretion. Furthermore, calyculin A blocked the reversal of renin secretion preinhibited by raised intracellular Ca2+ concentrations in a concentration-dependent manner. Calyculin A (10(-6) M) significantly inhibited renin secretion stimulated by lowering intracellular Ca2+ concentrations and blocked the stimulatory effect of ML-9 on renin secretion. Taking all of these results into consideration, we hypothesize that dephosphorylation of MLC20 by Ca2+-independent PP1 stimulates renin secretion, whereas phosphorylation of MLC20 by Ca2+-calmodulin-dependent MLCK inhibits it. This hypothesized regulatory model of renin secretion predicts that the rate of renin secretion at a given time is determined by the ratio of phosphorylated to dephosphorylated MLC20, which is, in turn, determined by the dynamic balance between activity of MLCK and MLC phosphatase.