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.

Cine MR CSF flow study in hydrocephalus: what are the valuable parameters?

To evaluate the changes of intracranial cerebrospinal fluid (CSF) dynamics in hydrocephalus, we studied the various parameters of cine phase contrast (PC) magnetic resonance (MR) CSF flow images in cases of acutely progressive hydrocephalus, comparing them with those in normal CSF circulation. The MR images were obtained with 1.5 T unit using the 2 dimensional cine PC sequence with cardiac gating in 10 non-obstructive hydrocephalus (NOH), 3 obstructive hydrocephalus (OH), and 10 controls. The temporal velocity information from the anterior and posterior cervical pericord spaces, third and fourth ventricles, and aqueduct were plotted as wave form. The wave forms were analyzed for configurations, amplitude parameters (Smax, Smin, Sdif), and temporal parameters (R-S, R-SMV, R-D, R-DMV). The statistical significance of each parameter was examined with paired t-test. All patients with OH underwent endoscopic thrid ventriculostomy, whereas all NOH underwent shunting procedures. In 5 ROIs, distinct reproducible configuration features were obtained at aqueductal and cervical pericord spaces. Statistically significant differences between control and hydrocephalus only in temporal parameters were determined. In NOH, the graph showed R-DMV shortening (p < 0.01) at anterior cervical pericord space. In OH, there were R-DMV shortening (p < 0.05) at anterior cervical pericord space, R-SMV shortening (p < 0.02) at posterior cervical pericord space. Also the level of obstructions could be determined in all OHs. The analysis of MR CSF flow images may give us valuable information on the site of obstruction, explaining the cause of hydrocephalus, thus deciding the necessity of shunting procedures using in vivo images.

Surgical options of hypertensive intracerebral hematoma: stereotactic endoscopic removal versus stereotactic catheter drainage

The authors analyzed the difference between two surgical procedures, stereotactic endoscopic removal (SER) and stereotactic catheter drainage (SCD), in 18 patients of ganglionic intracerebral hematoma (ICH). Ten patients underwent SCD and eight SER within 24 hours of insult. The mean age was 53.3 (33-81) years and male to female ratio was 11:7. The mean volume of hematoma was 34.4 (23-105) ml. All patients had major neurological deficits without signs of transtentorial herniation. Mean follow-up was 8 (6-10) months. Under local anesthesia, Otzuki's cannula was placed through a burr hole. ICH was removed with suction and forceps under endoscopic guidance. Hemostasis was performed with Nd-YAG laser. For SCD, we used silicone catheter and urokinase. The hematoma was drained in 3-5 days in SER, whereas 7-10 days in SCD. Postoperative rebleeding occurred in one case of SER. Mortality rate was 13% in SER, 10% in SCD. The patients who gained most from these treatments were those who had been admitted with an impaired level of consciousness. The whole procedure can be done under direct vision in SER, so SER might replace SCD with similar mortality.

Routine biliary sphincterotomy may not be indispensable for endoscopic pancreatic sphincterotomy

BACKGROUND AND STUDY AIMS

It is generally accepted that biliary sphincterotomy is mandatory to avoid possible cholestasis and infection due to edema after pancreatic sphincterotomy. However, biliary sphincterotomy is an invasive procedure and the above claim on dual sphincterotomy has not been proven by a prospective randomized study. The aim of our study was to determine whether cholangitis develops more frequently when the patients have not undergone concomitant biliary sphincterotomy during the endoscopic pancreatic sphincterotomy.

PATIENTS AND METHODS

From January 1990 to November 1997, 60 patients (38 men, 22 women, age range 19-45 years) with non-alcoholic chronic calcifying pancreatitis were prospectively enrolled. The patients with jaundice (bilirubin > or = 3 mg/dl), cholangitis, or parenchymal liver disease were excluded. The patients were randomly subjected either to dual sphincterotomy (group I, n = 30) or to pancreatic sphincterotomy alone (group II, n = 30). Groups I and II were further classified as IA (or IIA) and IB (or IIB), according to the level of serum alkaline phosphatase (sALP) and the diameter of the common bile duct (CBD). Group IA (or IIA) was defined when abnormal in both sALP (> or = 2 times the upper limit of normal) and CBD diameter (> or = 12 mm), whereas group IB (or IIB) was defined when normal, or solely abnormal in sALP or CBD diameter.

RESULTS

As a complication after sphincterotomy, pancreatitis developed in one of eight patients (12.5%) in group IA, whereas cholangitis occurred in one of 22 (4.5%) and hemorrhage in one of 22 (4.5%) cases in group IB. By contrast, in group IIA, the cholangitis developed in 56% (five of nine patients), which was significantly more frequent than in any other groups (P < 0.05). Hemorrhage (one of 21, 4.8%) and pancreatitis (one of 21, 4.8%) occurred in group IIB.

CONCLUSIONS

Our results suggest that dual sphincterotomy may be indicated only in patients who have both dilated choledochus and elevated alkaline phosphatase in chronic pancreatitis. Routine biliary sphincterotomy may not be indispensable for pancreatic sphincterotomy.

Treatment of total hyphema with relatively low-dose tissue plasminogen activator

The purpose of this study is to investigate the efficacy of tissue plasminogen activator (tPA) in the treatment of total hyphema following ocular trauma or intraocular surgery. Three patients (3 eyes) representing unresolved total hyphema for more than 5 days and uncontrolled high intraocular pressure received intracameral injections of 10 microgram of recombinant tPA. Intracameral tPA injection resulted in complete resolution of hyphema in all 3 eyes. Resolution occurred mostly within 24 to 48 hours after injection. Possible side effects of tPA injection, such as increased intraocular pressure and corneal edema, were not observed. However, 1 eye had vitreous hemorrhage after repeated injections of tPA. Intracameral injection of tPA seems to be a safe and effective method for the treatment of unresolved total hyphema. However, repeated intracameral tPA injections may cause unwanted complications such as vitreous hemorrhage.

Ballooning of the papilla during contrast injection: the semaphore of a choledochocele

BACKGROUND

Choledochocele is a rare abnormality involving the intramural segment of the common bile duct. ERCP is essential to demonstrate a choledochocele. The aim of this study was to investigate the duodenoscopic and cholangiographic findings during ERCP.

METHODS

Over a 4-year period, 17 symptomatic patients (8 men, 9 women; age range 45 to 83 years) were identified as having choledochoceles. The diagnosis of choledochocele was made by both duodenoscopic and cholangiographic findings.

RESULTS

As a characteristic duodenoscopic finding, the enlarged bulging papilla was noted in 8 patients (47%), whereas a normal-appearing papilla was noted in 9 patients (53%) before the injection of contrast media. However, in all 17 patients progressive enlargement or ballooning of the papilla was noted during contrast injection. The maximum diameter of the choledochocele, determined by cholangiography, was significantly larger (19 +/-4 mm) in patients with initially bulging papilla than in those with normal-appearing papilla (9+/-3 mm) (p < 0.05).

CONCLUSIONS

Ballooning of the papilla during contrast injection may be a specific duodenoscopic finding for choledochocele. To avoid missing the diagnosis of a choledochocele, especially when it is small, it is important to watch the papilla carefully during contrast injection.

Association of periampullary diverticula with primary choledocholithiasis but not with secondary choledocholithiasis

BACKGROUND AND STUDY AIMS

Several endoscopic studies have reported an association between periampullary diverticula and biliary calculi, but the results are inconsistent when the anatomic site of the stones is considered. The aims of our study are to evaluate the association between periampullary diverticula and gallstones according to their site and to clarify the origin of the common bile duct stones by analyzing their composition.

PATIENTS AND METHODS

During a period of 10 months, 611 of 632 consecutive patients having endoscopic retrograde cholangiopancreatography (ERCP) were prospectively enrolled. The data about periampullary diverticula and gallstones were analyzed according to the site of the stones. The stones were initially grouped on the basis of their gross morphology and cross-sectional appearance, and finally analyzed by quantitative infrared spectroscopy.

RESULTS

Diverticula were found in 165 of 611 cases (27%) and the incidence increased with age (p<0.01). The incidence of gallbladder or common bile duct stones was higher in patients with periampullary diverticula (73/165,44%) than without (130/446,29%) (p<0.01). Considering the site of the gallstones, this significance was found only in patients with common bile duct stones not associated with gallbladder stones (p<0.001). Of the 40 who had gallstones only in the common bile duct, 32 gave a history of cholecystectomy more than two years previously and had been free of symptoms postoperatively, and on analysis most of the stones (30/36,83%) were brown pigment stones. These therefore were assumed to be primary common bile duct stones. The common bile duct stones with associated gallbladder stones were identical to their paired gallbladder stones in gross and cross-sectional appearance and chemical composition. They were assumed to be secondary common bile duct stones and the difference in the incidence of calculi according to the presence of diverticula was not significant.

CONCLUSION

The incidence of gallstones was significantly higher in periampullary diverticula, and when the site and the origin of the gallstones was considered the association between diverticula and gallstones was significant in patients with primary common bile duct stones but not with the secondary ones.

Two metal-binding sites in a lead ribozyme bound to competitively by Pb2+ and Mg2+--induced structural changes as revealed by NMR

We reported recently that a lead ribozyme with modified bases cleaved at an additional site at high Pb2+ concentrations (>0.1 mM), and that the cleavage at a canonical site was enhanced nearly fourfold at the optimum combination of Pb2+ and Mg2+ concentrations [Kim, M. H., Katahira, M., Sugiyama, T. & Uesugi, S. (1997) J. Biochem. (Tokyo) 122, 1062-1067]. Here we have identified two metal-binding sites (sites 1 and 2) of the lead ribozyme at the residue level by NMR. Both sites are located in an asymmetric internal loop of the lead ribozyme. Site 1 is composed of residues of an enzyme strand and site 2 of residues of a substrate strand. The two sites are bound to competitively by Pb2+ and Mg2+. It was revealed that at certain Pb2+ and Mg2+ concentrations, site 1 is occupied by Pb2+ and site 2 is occupied by Mg2+. The dependency of the cleavage at the canonical and other sites on the Pb2+ and Mg2+ concentrations is interpreted by considering the species of metal ions bound to the two sites. It is suggested that the addition of the two metal ions produces similar and different effects on the structure of the lead ribozyme, and the two metal ions have a synergistic effect on the structure.

Cloning and sequencing of a cyclodextrin glycosyltransferase gene from Brevibacillus brevis CD162 and its expression in Escherichia coli

A cyclodextrin glycosyltransferase (CGTase) gene of Brevibacillus brevis CD162 was cloned into Escherichia coli using pUC19 as a vector. Determination of the nucleotide sequence showed the presence of an open reading frame of 2079 bp encoding a polypeptide of 693 amino acid residues, composed of a 20-amino acid signal sequence and a 673-amino acid mature enzyme. Neither a TATA- nor a TTGA-like sequence was observed within the cloned DNA fragment. However, the fragment was expressed in Escherichia coli by the lac promoter of pUC19 and 74% of the total activity was secreted into the fermentation medium. The amino acid sequence of the mature CGTase showed the highest homology of 86% to that of Bacillus sp. KC201. The CGTase purified to homogeneity from the recombinant E. coli exhibited the same properties as those of native CGTase from Brevibacillus brevis CD162 in terms of molecular mass, reaction conditions, stability and the production of cyclodextrins.

Evaluation of risk from space radiation with high-energy heavy ion beams

The most challenging radiation in space consists of fully ionized atomic elements with high energy for which only the few lowest energy ions can be stopped in shielding materials. The health risk from exposure to these ions and their secondary radiations generated in shield materials is poorly understood since there are few human data and a systematic study in relevant animal model systems has not been made. The accuracy of risk prediction is described as the major limiting factor in the management of space radiation risk. The expected impact of systematic studies is examined using the limited available biological data and models. Given the limitations of current predictions, models must be developed that are able to incorporate the required fundamental scientific data into accurate risk estimates. The important radiation components that can be provided for laboratory testing are identified. The use of ground-based accelerator beams to simulate space radiation is explained and quantitative scientific constraints on such facilities are derived. Three facilities, one each in the United States, in Germany and in Japan, currently have the partial capability to satisfy these constraints. A facility has been proposed using the Brookhaven National Laboratory Booster Synchrotron in the United States; in conjuction with other on-site accelerators, it will be able to provide the full range of heavy ion beams and energies required.

PAC and cosmid contig spanning the HOXA cluster on human chromosome 7p15

To construct the PAC and cosmid contig map spanning the HOXA cluster on human chromosome 7, we used 9 DNA markers (D7S2243, D7S3010, HOXA1, EVX1, 750, pBH8, p60, p8.0, and HOXA11), among which the final 4 were generated in this study by shotgun cloning strategy. From the libraries, 5 PAC and 35 cosmid clones were screened and as a result, an overlapping continuous array of cosmid and PAC clones covering the genomic region (about 200 kb) spanning the entire cluster were constructed. The isolated cosmids contained several consecutive HOX genes of regional group, probably sharing the regulatory processes such as alternative splicing or polyadenylation, and thus could be used as useful materials for elucidating the molecular mechanism of HOX gene expression in the future.

Dimeric inhibin: a direct marker of ovarian aging

OBJECTIVE

To investigate whether luteal secretion of inhibin-a is altered in the perimenopausal transition and to evaluate whether luteal inhibin secretion is correlated with other markers of ovarian reserve such as FSH and inhibin-b.

DESIGN

Prospective study.

SETTING

Reproductive Endocrinology Laboratories at The Ohio State University.

PATIENT(S)

Twenty-five women 39-52 years of age with regular menstrual cycles.

INTERVENTION(S)

Daily urine samples were monitored (LH predictor kit) to identify the day of ovulation. Blood samples obtained on days 6 and 8 after the LH surge and on day 3 of the subsequent follicular phase were assayed for FSH, E2, progesterone. inhibin-a, and inhibin-b.

MAIN OUTCOME MEASURE(S)

Serum levels of inhibin-a, inhibin-b, FSH, E2, and progesterone.

RESULT(S)

Luteal phase inhibin-a and follicular phase inhibin-b were correlated inversely with age in perimenopausal women. In addition, luteal phase inhibin-a and follicular phase inhibin-b levels were correlated inversely with follicular phase FSH levels.

CONCLUSION(S)

Both luteal phase inhibin-a and follicular phase inhibin-b levels are correlated inversely with age during the fifth decade of life. These findings suggest that corpus luteum function is altered during the perimenopausal transition. Moreover, these direct measures of ovarian function may be more sensitive indicators of "ovarian reserve" than indirect indicators such as pituitary FSH secretion.

Isolation and characterization of a pufferfish MLL (mixed lineage leukemia)-like gene (fMll) reveals evolutionary conservation in vertebrate genes related to Drosophila trithorax

The MLL gene is interrupted and fused to a number of partner genes as a result of chromosomal translocations in human leukemias. MLL is a very large protein with a unique domain structure and large regions of homology to Drosophila trx. To define the key structural and functional domains of the MLL protein in vertebrates, we have cloned the genomic region encoding an MLL-like gene in the compact model vertebrate genome of Fugu rubripes. While the similarity between the mouse and human MLL proteins is very high, a lower overall similarity is present between the Fugu and mammalian proteins. Several new highly conserved regions were identified in the portion of the protein included in the MLL leukemia-associated fusion proteins. The conserved nature of regions of similarity between vertebrate forms of MLL and the Drosophila TRX proteins, as well as other domains previously suggested to have a functional role in MLL (including the AT hooks and the DNA methyltransferase domain), was also observed. Therefore, strong evolutionary constraints limited sequence divergence within these domains. The information derived from this comparative analysis will form the basis for the functional study of the MLL protein, particularly as it relates to human leukemogenesis.