Application of ABO genotyping using polymerase chain reaction method to assess engraftment in bone marrow transplantation--a case report

We described a case of acute promyelocytic leukemia with O blood type who received bone marrow transplantation during a second remission from his HLA identical, B blood type sibling. Using PCR genotyping of the ABO group and analysis of the variable number of tandem repeats of the D1S80 locus, we could quickly document the successful early engraftment in this patient. We emphasize that the use of PCR ABO genotyping is a quick and valuable method which could be applied to assess the engraftment and its follow up in those transplant cases with donors of mismatched blood groups.

Effects of phosphodiesterase inhibitors on spontaneous electrical activity (slow waves) in the guinea-pig gastric muscle

1. The effects of the phosphodiesterase inhibitors caffeine, theophylline, isobutylmethylxanthine (IBMX) and rolipram on spontaneous electrical activity (slow waves) were studied in the circular muscle of the guinea-pig gastric antrum. 2. All the inhibitors reduced slow wave frequency without changing the membrane potential and the slow wave configuration, but at higher concentrations they blocked the slow waves and caused membrane hyperpolarization. In the presence of the inhibitors a low level of irregular electrical activity could be observed in many preparations. 3. Isoprenaline, forskolin, dibutyryl cAMP and 8-bromo-cAMP all produced effects essentially similar to those of phosphodiesterase inhibitors. K+ (12 mM) and removal of K+ both depolarized the membrane and these were not affected by IBMX (1-3 microM). A decrease in frequency caused by IBMX was also not significantly affected by 12 mM K+ or K+ removal and only partially antagonized by TEA or 4-aminopyridine. 4. These results suggest that an increase in intracellular cAMP inhibits pacemaker activity of slow waves. An increase in K+ conductance does not seem to be a major factor in this inhibition. Slow waves appear to be a compound electrical activity in a group of muscle cells and are likely to be disintegrated by xanthine derivatives.

Significance of c-erbB-2 expression in normal and neoplastic epithelium of biliary tract

There were few, but conflicting, reports dealing with the clinical significance of c-erbB-2 in biliary tract cancer. We evaluated the expression of c-erbB-2 in normal epithelium of bile ducts (n = 46), gallbladder cancer (n = 11), carcinoma of the ampulla of Vater (n = 18), and intrahepatic cholangiocarcinoma (CC) (n = 18). c-erbB-2 protein is present in 63% (29/46) of surface epithelium in large and septal bile ducts, but not in peripheral small ducts. Overexpression of the gene product was found in 27.8% (5/18) of intrahepatic CC, 27.8% (5/18) of carcinoma of the ampulla of Vater, and 63.6% (7/11) of gallbladder cancer. But, there was no c-erbB-2 overexpression in the hyperplasia or atypical hyperplastic bile duct epithelium (p = 0.002). In terms of prognostic implication, expression of c-erbB-2 did not correlate to the histopathological grade (p = 0.60) and tumor stage (p = 0.63). The results indicate that c-erbB-2 protein may play some roles in physiology of normal bile ducts. Overexpression of the gene product occurs in one forth to about two thirds of carcinoma of biliary tract, and may be used as phenotypic marker for neoplastic transformation. However, the gene product may not be important in the aggressive behavior of tumor.

Sustained contraction produced by caffeine after ryanodine treatment in the circular muscle of the guinea-pig gastric antrum and rabbit portal vein

1. Caffeine inhibited spontaneous mechanical activity at 0.3-1 mM, but produced a tonic contraction at concentrations higher than 3 mM in the circular muscle of the guinea-pig gastric antrum. In the circular muscle of the rabbit portal vein, caffeine at concentrations higher than 1 mM produced an early phasic contraction followed by a small tonic component. The caffeine-induced contraction was abolished by removal of the external Ca2+ more rapidly in the gastric antrum than the portal vein. 2. When the preparations were pretreated with ryanodine (1 microM) a sustained contraction developed on wash-out of caffeine (10 mM) both in the gastric antrum and portal vein. This contraction was not affected by nicardipine (3 microM) or verapamil (3 microM), but was readily abolished by removal of the external Ca2+ or by addition of cobalt (1 mM). Spontaneous electrical activity, the slow wave, in gastric muscles was blocked in the presence of 10 mM caffeine, but reappeared during the sustained contraction. 3. Both the contractions induced directly by caffeine and those produced following caffeine wash-out after ryanodine treatment were accompanied by a maintained increase in intracellular Ca2+ concentration measured with fura-2. 4. The presence or absence of Ca2+ during the application of ryanodine did not affect the ability of caffeine to initiate sustained contractions, provided Ca2+ was present during the exposure to caffeine. 5. It is concluded that caffeine can induce a sustained contraction after ryanodine treatment both in the guinea-pig gastric antrum and rabbit portal vein, by activating a Ca2+ influx pathway insensitive to organic Ca2+ channel blockers. No clear evidence was obtained for involvement of the Ca2+ influx pathway activated through depletion of intracellular Ca2+ stores. A hypothesis is proposed that the plasma membrane of these preparations is similar to the sarcoplasmic reticulum membrane in that Ca2+permeability can be increased almost irreversibly by a combination of caffeine and ryanodine in the presence of the external Ca2+.

MDR1 gene expression in acute myeloid leukemia: clinical correlation

Acute myeloid leukemia (AML) has a poor long-term prognosis, with a disease-free survival rate of only 20%. Drug resistance remains the major obstacle in this disease, although relatively little data are available on the correlation of multi-drug resistance (MDR) and clinical outcome. We examined 28 bone marrow samples from 24 patients with AML. The MDR1 RNA levels were determined by slot blot analysis. The incidence of positive expression of MDR1 mRNA in patients was 64.7% in samples from newly-diagnosed patients and 85.7% in relapse samples. The overall complete remission rate was 45%. However, the complete remission rate was lower for patients in the MDR1 RNA positive group than in the negative group. In three cases, the MDR1 RNA expression steadily rose during the period of disease progression and after several courses of chemotherapy. We suggest that a high frequency of MDR1 gene expression in patients with AML and higher MDR1 RNA levels are associated with a lower incidence of complete remission as well as a shorter disease-free time. The expression of MDR1 is a poor prognostic factor for AML treatment and it may play an important role in resistance to chemotherapy.

Characterization of the nuclease activity of Drosophila Rrp1 on phosphoglycolate- and phosphate-modified DNA 3'-termini

Drosophila Rrp1 includes a carboxy-terminal region homologous to Escherichia coli exonuclease III which is sufficient to repair both oxidative and alkylation damage to DNA. An apurinic/apyrimidinic endonuclease activity intrinsic to Rrp1 was characterized previously. In this work, the 3'-phosphodiesterase and 3'-phosphatase activities of Rrp1 are demonstrated and characterized. Phosphoglycolate- and phosphate-modified DNA 3'-termini are formed by oxygen radical induced DNA cleavage. To demonstrate the 3'-phosphodiesterase activity of Rrp1, a 3'-phosphoglycolate-terminated oligonucleotide substrate was generated by site-specific cleavage of a unique GpC dinucleotide by iron(II) bleomycin. Removal of the terminal phosphoglycolate is detected by mobility shift on a DNA sequencing gel. Rrp1 cleaves the phosphoglycolate and releases a product with a 3'-hydroxyl terminus. Phosphoglycolate is removed more readily than the 3'-terminal dGMP residue. Rrp1 phosphodiesterase activity is not inhibited by 120 mM NaCl, while the 3'-exonuclease is reduced 25-fold. Using a 3'-phosphate-terminated oligonucleotide, the phosphatase activity of Rrp1 is at least 25-fold lower than its phosphodiesterase or apurinic endonuclease, and 56-fold lower than exonuclease III activity on the identical substrate. Rrp1 3'-phosphatase is reduced 25-fold by 80 mM NaCl. These results were confirmed using an assay that measures the ability of Rrp1 to stimulate DNA synthesis on circular DNA substrates nicked by various DNA damage treatments. In that assay, Rrp1 poorly repairs 3'-phosphate-terminated nicks introduced by micrococcal nuclease. The significance of these enzymatic properties for the biological of Rrp1 is discussed.

Single amino acid changes alter the repair specificity of Drosophila Rrp1. Isolation of mutants deficient in repair of oxidative DNA damage

Drosophila Rrp1 has several tightly associated enzymatic activities, including double-strand DNA 3'-exonuclease, apurinic/apyrimidinic endonuclease, 3'-phosphatase, and 3'-phosphodiesterase. The carboxyl-terminal third of Rrp1, homologous to Escherichia coli exonuclease III, is sufficient to repair oxidative and alkylation-induced DNA damage in vivo. Using a screen for partial complementation of repair-deficient E. coli, we isolated three mutants of the nuclease domain of Rrp1: T462A, K463Q, and L484P, that protect against methyl methanesulfonate (MMS)-induced but not t-BuO2H-induced DNA damage. Thr-462 and Lys-463 are highly conserved residues found in a cluster of 5 conserved amino acids (LQETK), while Leu-484 is poorly conserved. Gln-460 Glu-461, Thr-462, and Lys-463 and Leu-484 were altered by site-directed mutagenesis using a plasmid including the entire Rrp1 gene and mutant proteins were purified. Mutants of the three residues Glu-461, Thr-462, and Lys-463 demonstrate 8-200-fold lower phosphodiesterase specific activity than wild-type Rrp1. E461A has a 30-fold reduction in AP endonuclease and is MMS-sensitive, but all other mutants have near-normal AP endonuclease and are MMS-resistant. Glu-461 appears to be essential for the nuclease function for Rrp1. Lys-463 and, to a lesser extent, Thr-462 influence the substrate specificity of the Rrp1 nuclease.

[Rhinocerebral mucormycosis in a case of malignant lymphoma]

Mucormycosis, an uncommon opportunistic fungal infection, usually occurs in immunocompromised patients. It is rapidly progressive and almost always fatal. Patients with lymphoma are susceptible to pulmonary or disseminated mucormycosis, whereas rhinocerebral mucormycosis in such patients, as far as we know, is rarely reported. We present a patient with malignant lymphoma who exhibited such an acute rhinocerebral infection after chemotherapy which manifested initially as a stuffy nose and intractable headache. Then ptosis, proptosis, chemosis and multiple cranial nerve palsies appeared. Eschar was found in the nasal cavity. Direct KOH smear and tissue biopsy revealed mucormycotic infection. He survived because of early diagnosis and prompt treatment.

Dissociation of pigeon-liver malic enzyme in reverse micelles

Pigeon-liver malic enzyme has a tendency to aggregate at a large concentration of protein. The larger aggregates (hexamer and octamer) were demonstrated to be enzymically active with specific activity similar to that of the tetramer. When the enzyme was embedded in a reverse micellar system prepared by dissolving the surfactant sodium bis(2-ethylhexyl)-sulfosuccinate (AOT) in isooctane, the tetrameric enzyme dissociated into monomers. The dissociated monomers were also enzymically active but with diminished specific activity relative to the activity in aqueous media. The decreased enzyme activity in reverse micelles was due to interactions of surfactant with the enzyme molecules, suggesting that the cytosolic malic enzyme is located near the plasma membrane. When the dissociation was monitored by altering the degree of hydration of the system (represented by the ratio [H2O]/[AOT]), the detergent and organic solvent slightly affected KTD, the dissociation constant of tetramer to dimers (T <--> 2 D), but increased KDM, the dissociation constant of dimer to monomers (D <--> 2 M), by 1-2 orders of magnitude; this change caused a 2-3 orders of magnitude increase in the overall dissociation constant KTM (T <--> 4 M). The dissociation of the tetrameric malic enzyme to monomers was favored by approximately 16 kJ/mol in AOT/isooctane reverse micelles versus aqueous media. We propose water-shell and induced-fit models for the enzyme in AOT/isooctane reverse micelles at large and small [H2O]/[AOT] ratios to explain this data, respectively. The asymmetric quaternary structure of the enzyme [Lee, H. J. & Chang, G. G. (1990) FEBS Lett. 277, 175-179] was re-evaluated in terms of the subunit interactions and various interconvertible enzyme forms.

Successful resection of a minute icteric hepatocellular carcinoma--case report

A 38-year-old male was admitted to our department with jaundice. Imaging studies including ultrasonography, ERCP, PTC and computed tomography (CT) revealed a hilar lesion. Right hepatic lobectomy, caudate lobectomy, excision of CBD and restoration of biloenteric continuity was performed. Pathological examination showed an icteric hepatoma (1.2 x 0.8 x 0.8 cm in size) originating in the caudate lobe. The tumor thrombus occupied the common hepatic duct and the right intrahepatic duct. The postoperative course was fairly unremarkable, and the patient has remained in good health for four years after surgery without any sign of recurrence.

A pharmacokinetic evaluation of HIV protease inhibitors, cyclic ureas, in rats and dogs

The pharmacokinetics of a series of novel cyclic, non-peptide inhibitors of HIV protease were studied in rats or dogs after intravenous and oral administration. Six symmetrically substituted cyclic urea compounds (XK234, XM311, XM320, XM321, XM323, and XM412), which effectively inhibited HIV virus replication, with IC90 values of 0.03-1.0 microM (0.017-0.76 microgram mL-1), were evaluated. Plasma concentrations were measured in rats and dogs using specific and sensitive HPLC methods. In rats, the maximum plasma concentrations of 0.21-1.88 micrograms mL-1 were detected within 1 h of oral administration of 10 mg kg-1 of the compounds. The elimination half-lives ranged from 1.25 to 3.3 h in rats and the absolute oral bioavailability ranged from 18 to 100%. In dogs, the maximum plasma concentration and absolute oral bioavailability were 4.37 micrograms mL-1 and 48%, 1.07 micrograms mL-1 and 16%, and 1.48 mg ML-1 and 38% for XK234, XM311, and XM323, respectively. The data demonstrated that the maximum plasma concentrations of these cyclic ureas were several times higher than the IC90 for inhibition of viral replication after single doses of 10 mg kg-1 in rats and dogs. With this combination of high potency against virus replication and good oral bioavailability, these cyclic ureas represent a new class of compounds that are suitable for development as therapeutic agents for the treatment of HIV-associated diseases.

Pharmacokinetics of HIV protease inhibitor DMP 323 in rats and dogs

DMP 323 is a symmetrically substituted cyclic urea compound with demonstrated activity against human immunodeficiency virus (HIV) in vitro. DMP 323 has been measured in rat and dog plasma via liquid-liquid extraction and HPLC. The limit of quantitation is 10 ng/ml using 0.5 ml plasma. Following an intravenous dose of 5 mg/kg to rats, DMP 323 exhibited an apparent volume of distribution at steady-state of 6.36 liters/kg and clearance of 7.12 liters/hr/kg. The same dose administered intravenously to dogs resulted in apparent volume of distribution at steady-state and clearance values of 2.28 liters/kg and 1.48 liters/hr/kg, respectively. Elimination half-lives were 0.95 hr in rats and 1.80 hr in dogs. DMP 323 was rapidly absorbed from oral solution doses in rats (3, 5, and 10 mg/kg) and dogs (5 and 10 mg/kg), achieving maximum plasma concentrations in 1 hr or less in both species. Absolute bioavailability of DMP 323 from oral doses ranged from 15 to 27% in rats and from 37 to 38% in dogs. Pharmacokinetics were unchanged in rats and dogs over 8-day t.i.d. and 5-day b.i.d. multiple oral dose regimens, respectively. Oral doses administered to fed animals resulted in lower plasma concentrations of DMP 323 than the same doses administered to fasted animals. Because of its in vitro high potency and acceptable pharmacokinetics, DMP 323 seems to be a worthy candidate for further study in the effort to develop an inhibitor of HIV protease for use in the therapy of AIDS.

Determination of DMP 728, a IIb/IIIa receptor antagonist, in rat and dog plasma by high-performance liquid chromatography with fluorimetric detection

A specific and sensitive HPLC assay for the determination of DMP 728 in dog and rat plasma has been developed. The method involves solid-phase extraction of DMP 728 and the internal standard from plasma using a C2 column. The extracted compounds are derivatized with benzoin under alkaline conditions. Using a mixture of acetonitrile and 0.1 M potassium phosphate buffer (25:75, v/v, pH 7.4) as mobile phase, the derivatized products are separated on a Regis semipermeable surface C8 column and monitored fluorometrically using 325 nm and 425 nm as excitation and emission wavelengths, respectively. The assay is linear from 2.5 to 1000 ng/ml in dog plasma and from 5 to 1000 ng/ml in rat plasma. The limit of quantitation is 2.5 ng/ml using 0.5 ml of dog plasma and 5 ng/ml using 0.5 ml of rat plasma. The assay has been used in pharmacokinetic studies of DMP 728 in dogs and rats.

Affinity cleavage at the putative metal-binding site of pigeon liver malic enzyme by the Fe(2+)-ascorbate system

Pigeon liver malic enzyme was rapidly inactivated by micromolar concentrations of ferrous sulfate in the presence of ascorbate at neutral pH and 0 or 25 degrees C. Omitting the ascorbate or replacing the ferrous ion with manganese ion did not lead to any inactivation. Manganese, magnesium, zinc, cobalt, or calcium ion at 200 molar excess over ferrous ion offered complete protection of the enzyme from Fe(2+)-induced inactivation. Ni2+ provided partial protection, while Ba2+ or imidazole was ineffective in protection. Addition of 4 mM Mn2+ or 5 mM EDTA into a partially modified enzyme stopped further inactivation of the enzyme. Inclusion of substrates (L-malate or NADP+, singly or in combination) in the incubation mixture did not affect the inactivation rate. The enzyme inactivation was demonstrated to be followed by protein cleavage. Native pigeon liver malic enzyme had a subunit M(r) of 65,000. The inactivated enzyme with residual activity of only 0.3% was cleaved into two fragments with M(r) of 31,000 and 34,000, respectively. The cleavage site was identified as the peptide bond between Asp258 and Ile259. Native pigeon liver malic enzyme was blocked at the N-terminus. Cleavage at the putative metal-binding site exposed a new N-terminus, which was identified to be at the 34-kDa fragment containing the C-terminal half of original sequence 259-557. Our results indicated that Fe2+ catalyzed a specific oxidation of pigeon liver malic enzyme at Asp258 and/or some other essential amino acid residues that caused enzyme inactivation. The modified enzyme was then affinity cleaved at the Mn(2+)-binding site.

Hyperammonemic encephalopathy due to essential amino acid hyperalimentation

Hyperammonemic encephalopathy has occasionally been reported in uremic patients receiving hyperalimentation with essential amino acid (EAA) as a source of nitrogen as one of the remaining treatment options when the enteric routes were prohibited. We encountered this complication in a patient with normal renal function. A rat animal model was designed to elucidate the mechanism of hyperammonemia resulting from hyperalimentation with EAA as a source of nitrogen. Sixty-four male Long-Evan rats were divided into eight groups receiving feeds ad libitum or different formula of hyperalimentation. Hyperammonemia was found in every rat given hyperalimentation with EAA as the only nitrogen source. Using the Tukey honestly significant difference test, the results were significantly higher (p < 0.001) than that of the control group which were given feeds ad libitum and those groups given hyperalimentation for the same number of days but with mixed amino acid (MAA) as the nitrogen source. Adding arginine to EAA for a further four days after initial administration of EAA hyperalimentation for three days only slightly lowered the mean serum ammonia level. When compared to that of the three-day EAA hyperalimentation group, the difference was not statistically significant. Adding arginine, citrulline, and ornithine to EAA for a further four days significantly lowered the mean serum ammonia level. When we changed EAA hyperalimentation to MAA hyperalimentation for a further four days, the mean serum ammonia level decreased dramatically to nearly normal. Hyperalimentation using EAA as the exclusive source of nitrogen resulted in hyperammonemia. A deficiency of arginine or other amino acids of the urea cycle failed to account completely for the hyperammonemia observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Cloning and expression of pigeon liver cytosolic NADP(+)-dependent malic enzyme cDNA and some of its abortive mutants

A full-length 1927-base-pair cDNA of pigeon liver malic enzyme was obtained by utilizing the screening of the cDNA library and polymerase chain reaction techniques. The cDNA contained one open reading frame coding for 557 amino acid residues, flanked by 86 and 167 nucleotides at the 5' and 3' termini, respectively, and was successfully cloned and expressed in Escherichia coli cells. Functionally active recombinant malic enzyme was purified from the cells. This recombinant enzyme has a Km value for L-malate of 160 +/- 30 microM, which is almost identical to that for the natural enzyme (150 +/- 17 microM). The Km value for Mn2+ (4.2 +/- 0.3 microM) is higher than that for the natural pigeon malic enzyme (1.4 +/- 0.2 microM), while the Km value for NADP+ (3.8 +/- 0.3 microM) is lower than that for the natural enzyme (10.8 +/- 0.1 microM). The catalytic constant (kcat) for the recombinant enzyme is decreased by 3.6-fold, but the substrate inhibition constant for L-malate is increased by about 40-fold. Change in the quaternary structure of the recombinant enzyme was revealed in the pH perturbation examination. A truncated pigeon liver malic enzyme, lacking the first 13 amino acid residues, and a recombinant protein, mutated at F19S, N250S, and L353Q, showed no enzymatic activity. Both abortive recombinant mutant proteins were still able to bind with 2',5'-ADP agarose; however, the fluorescence emission spectrum of the protein bound NADPH did not show a blue shift as the natural enzyme. In accordance with these observations, we suggest that the adenosine 2',5'-bisphosphate binding domain of the NADP+ binding site in the beta alpha beta motif may still be retained in these mutant proteins. However, the local hydrophobic environment for the binding of the nicotinamide moiety of the coenzyme molecule may be altered. Therefore, the lack of catalytic activity of the mutant proteins could be attributed to an improper orientation of the bound NADP+.

Comparison of aged and young adult patients with cholelithiasis: a prospective controlled study

BACKGROUND

Surgical operations for gallstones are associated with increased perioperative mortality in the elderly. The presence of pre-existing cardiovascular disease and acute cholangitis might be the cause as found in the literature.

METHODS

From August 1989 to December 1990, twenty-nine patients (Age > or = 70 years) with cholelithiasis undergoing biliary surgery in Veterans General Hospital-Taipei were collected as experimental group. Twenty-nine patients from 62 patients (Age < or = 50 years) with cholelithiasis were selected as control group. The basic data, symptomatology, blood biochemistry, peri-operative complications, mortality and gallstone compositions were analyzed and compared between both groups.

RESULTS

There was a higher male to female ratio (4.8:1) in the aged group. Aged patients had higher incidence of common bile duct stone (11/29 versus 3/29, P < 0.025), while young adult patients had higher incidence of intrahepatic stone (1/29 versus 10/29, P < 0.05). The perioperative morbidity and mortality was higher in the aged group (37.9% and 3.4%) as compared with the young age group (3.4% and 0%, P < 0.005).

CONCLUSIONS

Aged cholelithiatic patients were associated with male preponderance, more common bile duct stones, higher perioperative morbidity and mortality, as compared with the young adult cholelithiatic patients.

Pharmacokinetics and bioavailability of bemoradan, a long-acting inodilator in healthy males

Bemoradan is a potent, long-acting orally active inodilator. The pharmacokinetics and bioavailability of bemoradan were studied in twelve normal males following oral administration of single, ascending doses of the bemoradan HCL salt in capsules. Plasma and urine levels of bemoradan were determined by HPLC (detection limits: approximately 0.5 ng/ml for plasma and 5 ng/ml for urine). Bemoradan was rapidly absorbed from the capsule formulation at all doses (Cmax occurred at 2.1-2.4 hours). Bemoradan was slowly eliminated from the body (harmonic mean t1/2 16-23 hours). There was a dose-proportional increase in the AUC (0-48) values of bemoradan in humans following the administration of 0.5, 1, 1.5 and 2 mg of bemoradan. The AUC (0-48) values increased to 2.3, 3.4 and 4.0 times when the dose was increased to 2, 3 and 4 times. Urinary excretion of unchanged bemoradan accounted for approximately 5-12% of the dose. Results from this study and previous studies in rats and dogs indicate that bemoradan is well and rapidly absorbed after oral dosing, has linear pharmacokinetics and long elimination half-lives across species.

The pharmacokinetics and metabolism of DuP 532, a non-peptide angiotensin II receptor antagonist, in rats and dogs

DuP 532, 2-propyl-4-pentafluoroethyl-1-([2'-(1H-tetrazol-5-yl)biph eny l-4-]methyl) imidazole-5-carboxylic acid, is an orally active, non-peptide angiotensin II (AII) receptor antagonist. DuP 532 is more potent and longer acting than losartan, another AII receptor antagonist currently undergoing phase III clinical trials. The pharmacokinetics and the effect of the salt form on the bioavailability of DuP 532 were determined in rats and dogs. In rats, the absolute oral bioavailability and half-life averaged 8.0% and 3.5 h, respectively, after the sodium bicarbonate solution and 7.6% and 3.6 h, respectively, after the methyl cellulose suspension. In dogs, the absolute oral bioavailability averaged 13.4% after the sodium bicarbonate solution and 11.9% after hard gelatin capsules containing the neat powder. The data demonstrated that there were no differences in bioavailability between the free acid and the sodium salt of DuP 532 after oral administration to rats and dogs. The in vitro metabolism of 14C-DuP 532 was evaluated with rat, dog, and human liver microsomes. HPLC analyses with UV and radiochemical flow detection showed that recovery of DuP 532 was greater than 99%, suggesting that there was little if any metabolism by liver microsomal enzymes. Therefore, the low oral bioavailability in rats was probably due to poor absorption of DuP 532 from the GI tract rather than extensive metabolism.

Bile duct injury and bile leakage in laparoscopic cholecystectomy

Between January 1991 and July 1992, 350 laparoscopic cholecystectomies were performed. There were six biliary complications (1.7 per cent): common bile duct (CBD) injury (one patient), delayed CBD necrosis (one), immediate postoperative bile leakage (one) and delayed bile leakage (three). All six patients required laparotomy. Primary repair with long-arm T tube splinting for 3 months was performed for the CBD injury. Religation of the cystic duct was carried out after immediate postoperative bile leakage. Laparotomy with T tube choledochostomy only was performed in the three patients with delayed bile leakage, and hepatojejunostomy Roux-en-Y was undertaken for CBD necrosis. The patient with primary repair of the CBD injury required choledochojejunostomy Roux-en-Y 18 months later for stenosis. Episodes of intermittent cholangitis occurred in the patient with CBD necrosis. The outcome for the four patients with bile leakage was good. There were no deaths.

High-performance liquid chromatographic determination of a potent AII receptor antagonist (DMP 811) in plasma

An HPLC assay for DMP 811, 4-ethyl-2-propyl-1-[(2'-(1H-tetrazol-5-yl)biphenyl-4-yl)methyl]imi dazole-5- carboxylic acid (I) in rat and dog plasma has been developed. Compound I was isolated from plasma using a liquid-liquid back extraction procedure. The extraction recovery was greater than 81%. Separation of I from endogenous components in plasma was achieved on an E. Merck C8 column using a mobile phase of 0.05 M ammonium acetate, brought to pH 3.75 with acetic acid, and acetonitrile (78:22, v/v). The eluent was monitored by fluorescence with excitation and emission set at 235 and 370 nm, respectively. The assay was linear from 2 to 2000 ng/ml. Inter- and intra-day coefficients of variation for the rat-plasma assay ranged from 0.9 to 5.2% (5-2000 ng/ml) and 2.7 to 16.5% (2-2000 ng/ml), respectively. The respective coefficients of variation for the dog-plasma assay were 1.9 to 5.6% and 1.2 to 14.0%. The percent differences from the accuracy results were 12% or less. Using 0.5 ml of plasma for extraction, the minimum quantifiable limit was 2 ng/ml. This method has been used to quantify plasma levels of I in rats or dogs following 3-10 mg/kg i.v. or p.o. doses.

Characterization of the apurinic endonuclease activity of Drosophila Rrp1

Drosophila Rrp1 (Recombination repair protein 1) belongs to a family of DNA repair nucleases that includes Escherichia coli exonuclease III, Streptococcus pneumoniae exonuclease A, bovine BAP, mouse APEX endonuclease, and human APE. Within a 252 amino acid region, colinear homology is shared between all members. Rrp1 is unique in that it includes a 427 amino acid N-terminal region not related to any known sequence. The protein copurifies with an apurinic endonuclease and a double-stranded DNA 3'-exonuclease. In this study, a 5'-end-labeled 37 base pair oligonucleotide substrate containing a single apurinic site was used to characterize the endonuclease activity of Rrp1. This substrate is utilized efficiently by Rrp1: the specific activity observed is 1 x 10(5) units/mg. The abasic double-stranded DNA oligonucleotide is cleaved only at the abasic site to create a single-strand break. Strand breaks are not detected in the complementary strand, in the single-stranded DNA oligonucleotide, or in the base-paired control substrate. After endonucleolytic cleavage at the abasic site, exonucleolytic processing at the nick is slow and requires a molar excess of Rrp1, while exonuclease III degrades the nicked substrate more efficiently. The Rrp1 cleavage product comigrates with a DNaseI cleavage product, and the newly formed terminus supports DNA synthesis by DNA polymerase. Therefore, Rrp1 cleaves the phosphodiester backbone at one position 5' to the apurinic site and leaves a 3'-hydroxyl terminus. Rrp1 is a class II apurinic endonuclease and is likely to be important in DNA repair in Drosophila.

Drosophila Rrp1 complements E. coli xth nfo mutants: protection against both oxidative and alkylation-induced DNA damage

Drosophila Rrp1 protein has four tightly associated enzymatic activities: DNA strand transfer, ssDNA renaturation, dsDNA 3'-exonuclease and apurinic/apyrimidinic (AP) endonuclease. The carboxy-terminal region of Rrp1 is homologous to Escherichia coli exonuclease III and several eukaryotic AP endonucleases. All members of this protein family cleave abasic sites. Rrp1 protein was expressed under the control of the E. coli RNA polymerase tac promoter (pRrp1-tac) in two repair deficient E. coli strains (BW528 and LG101) lacking both exonuclease III (xth) and endonuclease IV (nfo). Rrp1 confers resistance to killing by oxidative, antitumor and alkylating agents that damage DNA (hydrogen peroxide, t-butylhydroperoxide, bleomycin, methyl methanesulfonate, and mitomycin C). Complementation of the repair deficiency by Rrp1 provides up to a two log increase in survival and requires the C-terminal nuclease region of Rrp1, but not its N-terminal region. The AP endonuclease activity in extracts from the repair deficient strain LG101 is increased up to 12-fold when the strain contains pRrp1-tac. These results indicate that pRrp1-tac directs the synthesis of active enzyme, and that the nuclease activities of Rrp1 are likely to be the cause of the increased resistance to DNA damage of the mutant cells.

Effects of cromakalim on the electrical slow wave in the circular muscle of guinea-pig gastric antrum

1. In circular muscle strips of the antrum of guinea-pig stomach, the effects of cromakalim were studied on mechanical activity and intracellular membrane potential. 2. Cromakalim inhibited mechanical activity at concentrations higher than 1 microM, accompanied by membrane hyperpolarization and a decrease in membrane resistance. The hyperpolarization was markedly potentiated in K(+)-free solution and was still observed in the absence of Na+. 3. Slow wave electrical activity was relatively resistant to cromakalim. Changes in its amplitude and frequency were not consistent but blockade of slow waves was never observed. In many preparations cromakalim induced spike-like potentials at the top of slow waves, or when spike-like potentials already existed they were potentiated. However, mechanical activity was always inhibited. 4. Inhibition by cromakalim of the phasic contractions associated with the slow waves, could not be reversed by increasing the external K+ concentration (12-30 mM). 5. The results suggest that in guinea-pig stomach muscle mechanical suppression by cromakalim does not simply result from membrane hyperpolarization or from inhibition of slow waves. A clear dissociation was found between the mechanical and electrical activities. Slow waves, particularly their frequency, are relatively insensitive to membrane hyperpolarization.

Metabolism and disposition of EXP631--a novel antidepressant analgesic

EXP631, 4-(3-thienyl)-alpha, alpha,1-trimethyl-4-piperidine-methanol hemi-fumarate salt (I), is a centrally acting non-opioid analgesic compound with monoamine uptake blocking properties. EXP631 has analgesic effects in several animal models. It is intended to be used for the treatment of moderate to moderately severe acute and chronic pain. To characterize the disposition of EXP631, the plasma levels of EXP631 were determined in rats and dogs after single intravenous and oral doses. In rats, EXP631 was rapidly absorbed following a single oral solution dose of 5-20 mg kg-1 with maximum plasma levels detected within 1.2 h post dose. The absorption was complete with an oral bioavailability of 92-131%. The pharmacokinetics was dose independent as measured by either Cmax or AUC values. In fasted dogs, EXP631 was absorbed rapidly and well (F = 81%) from an oral solution with the maximum concentration detected at 20 min post dose. In fed dogs, the absorption from capsules was slower (1.38 h) compared to the solution, but the absorption was complete (F = 115%). An N-desmethyl metabolite (II) was found in both rat and dog plasma samples. The structure was confirmed by mass spectroscopy, nuclear magnetic resonance spectroscopy and comparative chromatographic retention times. The metabolite is inactive as an analgesic.

Vitamin A, Vitamin E or beta-carotene status and hepatitis B-related hepatocellular carcinoma

A case-control study was carried out in 59 patients with newly diagnosed hepatocellular carcinoma and 101 control subjects, who were all male hepatitis B carriers. The odds ratios of hepatocellular carcinoma occurring among hepatitis B carriers in the lowest quartile and those highest quartile of dietary and serum status were 5.3 (1.9 to 15.0) and 86.9 (20.0 to 377.2), respectively. The odds ratios for hepatitis B carriers in the lowest quartile and those in the highest quartile of dietary and serum beta-carotene status were 1.7 (0.7 to 4.1) and 5.0 (1.9 to 13.2). Vitamin E status did not differ in case patients and control subjects. Low education level, heavy consumption of alcohol, and smoking status were also associated with increased odds of hepatocellular carcinoma. Serum retinol, positively associated with dietary retinol, demonstrated an independent effect on hepatocellular carcinoma. This effect may reflect changes in the physiologic condition of the patients at the time of entering the hospital.

Expression of Drosophila Rrp1 protein in Escherichia coli. Enzymatic and physical characterization of the intact protein and a carboxyl-terminally deleted exonuclease-deficient mutant

Drosophila Rrp1 protein purified from embryos has four tightly associated enzymatic activities: DNA strand transfer, single-strand DNA renaturation, 3'-exonuclease, and apurinic endonuclease. Copurifying with these activities is a single polypeptide that has an apparent M(r) of 105,000 when estimated by SDS-polyacrylamide gel electrophoresis. To determine if this polypeptide is sufficient for these activities, it has been overexpressed in Escherichia coli. In crude extracts of E. coli cells, an ATP-independent Mg(2+)-dependent strand transfer activity is observed upon activation of the promoter that drives expression of Rrp1. Rrp1 protein purified from induced E. coli cells has electrophoretic, chromatographic, and enzymatic properties similar to those of Drosophila Rrp1 protein. The carboxyl-terminal region of Rrp1 (amino acids 428-679) is homologous to E. coli exonuclease III. Rrp1 deleted for this region cannot carry out DNA strand transfer, but can renature complementary single-strand DNA. The strand transfer activity of this truncated protein can be restored if DNA 3'-exonuclease is provided in trans by pretreating the double-strand DNA substrate with E. coli exonuclease III. This demonstrates a likely role of the exonuclease in the in vitro DNA strand transfer reaction carried out by Rrp1 protein. Such a role is also suggested by an analysis of the polarity of the strand transfer reaction.

Inhibitory effects of cyanide on mechanical and electrical activities in the circular muscle of gastric antrum of guinea-pig stomach

Effects of cyanide (CN) on spontaneous mechanical and electrical activities were studied in the circular muscle of the guinea-pig gastric antrum. CN (0.05-0.5 mM) inhibited both mechanical and electrical activities, but the inhibition was stronger in the former than the latter (slow wave). When glucose was removed for more than 30 min, slow wave was also blocked by CN. It is likely that ATP necessary for the generation of spontaneous activity can be supplied through either glycolysis or oxidative phosphorylation. CN slightly depolarized the membrane and the inhibition by CN was not affected by glibenclamide, a blocking agent of ATP-regulated K+ channel, suggesting that this channel is not activated by CN treatment. Basal level of intracellular Ca2+ measured with fura-2 tended to increase during the mechanical inhibition by CN. This was also clearly demonstrated in excess (60 mM) K+ solution. These results suggest that intracellular Ca2+ regulation is impaired and that there is uncoupling between intracellular Ca2+ and tension development in the presence of CN.

Simultaneous monitoring of bemoradan pharmacokinetics and hemodynamics in mongrel dogs

This study was designed to determine the relationship between the hemodynamic responses to bemoradan, a novel cardiotonic agent, and its plasma levels after single administration of an oral dose or a 15 minute i.v. infusion to mongrel dogs, and to demonstrate that the clinical capsule formulation of bemoradan elicits a pharmacological response in the dog. Four conscious, instrumented mongrel dogs received each of four bemoradan treatments (30 micrograms kg-1 i.v., 100 micrograms kg-1 i.v., 100 micrograms kg-1 suspension p.o., or 1 mg capsule p.o.) in a Latin square cross-over design. Plasma levels of bemoradan up to 24 h post-dosing were determined by HPLC. Cardiac contractility (dP/dt), heart rate, and arterial blood pressure were continuously monitored for 8 h and again at 24 h. Results of the study indicate that there was a significant correlation between bemoradan plasma levels and dP/dt. The 1 mg clinical capsule formulation was well absorbed when compared to an oral suspension and an i.v. dose. Peak increases in dP/dt of 64 per cent at 15 min for the suspension and 53 per cent at 1 h for the capsule were observed.

Human placental alkaline phosphatase. An improved purification procedure and kinetic studies

An improved method for the purification of human placental alkaline phosphatase is described. The partially purified enzyme from Sigma was further purified by successive Concanavalin A-Sepharose and Q-Sepharose chromatography. The whole procedure may be completed in one working day. Highly purified enzyme was obtained with a 39% yield. The intrinsic fluorescence of the enzyme decreased at elevated temperature. The conformation of the enzyme molecule was studied by the fluorescence quenching technique. Upward Stern-Volmer plots were obtained for the quenching data which suggested that, in addition to collisional quenching, static quenching was involved in the quenching mechanism. The dynamic and static quenching constants were found to be 0.7 +/- 0.16 M-1 and 0.44 +/- 0.1 M-1, respectively, using acrylamide as the quenching agent. The corresponding values were 0.43 +/- 0.23 M-1 and 0.84 +/- 0.18 M-1, respectively, with KI as the quenching agent. Mg2+ and PO4(3-) induced protein conformational changes which altered both the dynamic and static quenching constants. Mg2+ was found to be a non-essential activator for the placental alkaline-phosphatase-catalyzed hydrolysis of 4-nitrophenyl phosphate. At pH 9.8, Mg2+ increased Vmax by 1.2-fold without affecting the Kd of the substrate. The tetranitromethane-modified enzyme showed slower migration toward the anode on electrophoresis and increased Kd for Mg2+.

[Parathyroid storm: report of two cases]

Parathyroid storm in patients with primary hyperparathyroidism has previously been described as hyperparathyroid crisis, parathyroid intoxication or acute hyperparathyroidism. Whatever the nomenclature, all emphasize the severity and urgency of this disease entity. Although fewer than 200 cases have been described since the first report by Dawson in 1932, it is generally agreed that parathyroid storm is more prevalent than commonly appreciated. The symptoms and signs of the syndrome are not only due to the hypercalcemia, but also to the toxic effects of the parathyroid hormone (PTH). Its wide, but nonspecific clinical presentations make it easily confused with other cardiovascular or renal diseases. The mortality rate in untreated cases of parathyroid storm is essentially 100%. With combined medical-surgical treatment, it is still reported to be as high as 40%. Two patients with parathyroid storm were encountered at our institute recently, they both presented with severe hypercalcemia, consciousness disturbance and acute renal failure. The serum level of the intact form of PTH (iPTH) in both patients was greater than 1,000 pg/mL. Case 1, a 63-year-old female, presented with hypercalcemic crisis. Initially, good responsiveness to a saline infusion, steroids and furosemide administration was noted. Unfortunately, she became comatous after fine-needle aspiration of the parathyroid tumor. The recurrent storm was refractory to medical therapy, but was treated successfully by surgical removal of the single adenoma. This is a rare reported case regarding a hyperparathyroid storm after fine-needle aspiration of a parathyroid adenoma.(ABSTRACT TRUNCATED AT 250 WORDS)

Extracorporeal shock-wave lithotripsy of gallbladder stones

Recently, extracorporeal shock-wave lithotripsy has been introduced as a nonoperative treatment for gallstone disease. To evaluate its applicability in Taiwan, where cholesterol stones are not very frequent, 18 patients out of 194 (9.3%) were selected according to the Munich inclusion criteria to receive this treatment. Chenodeoxycholic acid and ursodeoxycholic acid were administered as adjunctive litholytic therapy. Twenty-eight sessions of lithotripsy were performed, resulting in a 83% satisfactory fragmentation rate (< or = 5 mm). No serious complications were encountered; however, two patients later underwent laparoscopic cholecystectomy. The stones disappeared in four patients after treatment, but recurred in one after discontinuation of oral bile acids. The long-term result was discouraging compared to European reports. A 13% stone-free rate was noticed at one year and 25% was anticipated during the 13-18 month follow-up. It is our conclusion that low eligibility, low cost-effectiveness and poor treatment results will restrict the wide-spread use of this nonoperative therapy in Taiwan.

Chromosome rearrangement by ectopic recombination in Drosophila melanogaster: genome structure and evolution

Ectopic recombination between interspersed repeat sequences generates chromosomal rearrangements that have a major impact on genome structure. A survey of ectopic recombination in the region flanking the white locus of Drosophila melanogaster identified 25 transposon-mediated rearrangements from four parallel experiments. Eighteen of the 25 were generated from females carrying X chromosomes heterozygous for interspersed repeat sequences. The cytogenetic and molecular analyses of the rearrangements and the parental chromosomes show: (1) interchromosomal and intrachromosomal recombinants are generated in about equal numbers; (2) ectopic recombination appears to be a meiotic process that is stimulated by the interchromosomal effect to about the same degree as regular crossing over; (3) copies of the retrotransposon roo were involved in all of the interchromosomal exchanges; some copies were involved much more frequently than others in the target region; (4) homozygosis for interspersed repeat sequences and other sequence variations significantly reduced ectopic recombination.

Hamartoma of spleen: a case report

Hamartoma of the spleen is a rare benign tumor. Only about 105 cases in English-writing literature were reported after first description by Rokitansky in 1861. We reported one case of asymptomatic splenic hamartoma in Taiwan which was found incidentally by ultrasonographic examination. Ultrasonography of abdomen revealed a slightly hypoechoic and nearly isoechoic tumor mass in the spleen. Computed tomography of the abdomen revealed a well-defined, low-attenuation mass in the spleen, which became isodense after contrast injection. Celiac arteriography and superselective splenic arteriography revealed a hypervascular mass with fine tumor vessels and tumor stains in the spleen. Splenectomy was performed and the microscopic examinations revealed typical red-pulp type hamartoma of the spleen.

Recombinant human fibrinogen and sulfation of the gamma' chain

Human fibrinogen and the homodimeric gamma'-chain-containing variant have been expressed in BHK cells using cDNAs coding for the alpha, beta, and gamma (or gamma') chains. The fibrinogens were secreted at levels greater than 4 micrograms (mg of total cell protein)-1 day-1 and were biologically active in clotting assays. Recombinant fibrinogen containing the gamma' chain incorporated 35SO4 into its chains during biosynthesis, while no incorporation occurred in the protein containing the gamma chain. The identity of the sulfated gamma' chain was verified by its ability to form dimers during clotting. In addition, carboxypeptidase Y digestion of the recombinant fibrinogen containing the gamma' chain released 96% of the 35S label from the sulfated chain, and the radioactive material was identified as tyrosine O-sulfate. These results clarify previous findings of the sulfation of tyrosine in human fibrinogen.

Pressure Dependence of Superconductivity in Single-Phase K 3 C 60

The superconducting compound K(3)C(60) (with transition temperature T(c) = 19.3 kelvin at ambient pressure), formed as a single phase by reaction of alkali vapor with solids of the icosahedral C(60) molecule (buckminsterfullerene), shows a very large decrease of T(c) with increasing pressure. Susceptibility measurements on sintered pellets showing bulk superconductivity are reported up to 21 kilobars of pressure, where T(c) is already less than 8 kelvin. The results are consistent with a piling up of the density of states at the Fermi level.

Kinetic comparison of caiman epsilon-crystallin and authentic lactate dehydrogenases of vertebrates

Kinetic comparison of epsilon-crystallins isolated from the avian and reptilian species and the authentic lactate dehydrogenases (LDHs) was undertaken in order to clarify the identities of these structural lens proteins in relation to their enzymatic activity. Caiman epsilon-crystallin similar to the previously characterized duck epsilon-crystallin appeared to possess a genuine and stable LDH activity as detected by nitro blue tetrazolium staining on polyacrylamide gels and conventional kinetic assays. Kinetic parameters for pyruvate, L-lactate, NAD+, and three structural analogues of the coenzyme in this epsilon-crystallin catalyzed reaction were also determined and compared. Despite the structural similarities between epsilon-crystallins and chicken heart LDH, differences in charge and kinetic properties have been revealed by native isozyme electrophoresis and kinetic analysis as examined by initial velocity and substrate inhibition studies. It is found that the kinetic data analyzed for caiman epsilon-crystallin were more fitted with a compulsory ordered Bi-Bi sequential mechanism similar to those for the authentic LDHs and duck epsilon-crystallin. Caiman epsilon-crystallin has for the first time been established as a heart-type LDH based on the kinetic analysis and comparison with the authentic heart- and muscle-type LDHs from pig and chicken.

Role of the conserved active site residue tryptophan-24 of human dihydrofolate reductase as revealed by mutagenesis

The active sites of all bacterial and vertebrate dihydrofolate reductases that have been examined have a tryptophan residue near the binding sites for NADPH and dihydrofolate. In cases where the three-dimensional structure has been determined by X-ray crystallography, this conserved tryptophan residue makes hydrophobic and van der Waals interactions with the nicotinamide moiety of bound NADPH, and its indole nitrogen interacts with the C4 oxygen of bound folate through a bridge provided by a bound water molecule. We have addressed the question of why even the very conservative replacement of this tryptophan by phenylalanine does not seem to occur naturally. Human dihydrofolate reductase with this replacement of tryptophan by phenylalanine has increased rate constants for dissociation of substrates and products and a considerably decreased rate of hydride transfer. These cause some changes in steady-state kinetic behavior, including substantial increases in Michaelis constants for NADPH and dihydrofolate, but there is also a 3-fold increase in kcat. The branched mechanistic pathway for this enzyme has been completely defined and is sufficiently different from that of wild-type enzyme to cause changes in some transient-state kinetics. The most critical changes resulting from the amino acid substitution appear to be a 50% decrease in stability and a decrease in efficiency from 69% to 21% under intracellular conditions.

The importance of loop region residues 40-46 in human dihydrofolate reductase as revealed by site-directed mutagenesis

Site-directed mutagenesis has been used to delete 2 residues (Gly45-Lys46) from a flexible "loop" region between residues 40 and 46 of human dihydrolate reductase. Steady-state kinetic studies show that the Km values for the deletion mutant enzyme for both dihydrofolate and nicotinamide adenine dinucleotide phosphate (reduced) (NADPH) as well as the pH rate profile are virtually identical to that of the wild type. In contrast, the Vmax value of the mutant enzyme is decreased 2.5-fold. The results suggest that the loop region may play a role in the catalytic efficiency but not necessarily in the binding of substrates. Agents such as KCl, urea, and organomercurials at concentrations which show activating effects on the wild-type human dihydrofolate reductase have little or no effect on the deletion mutant. Competitive enzyme-linked immunosorbent assay experiments using peptide-specific antibodies against cyanogen bromide fragments generated from human dihydrofolate reductase show that the binding of folate, NADPH, and methotrexate, either in binary or in ternary complexes with the wild-type enzyme, causes a striking reduction in the binding of the antibodies. Compared with wild type, the binding of these ligands with the deletion mutant enzyme causes much less inhibition (2-16-fold less) in the binding of all three antibodies. The altered properties of the mutant enzyme can be explained on the basis of a need for the flexible loop 40-46 for reversible protein unfolding during activation and also for conformational changes induced by ligand binding, thus "communicating" the effects of ligand binding.

Mapping the antigenic epitopes of human dihydrofolate reductase by systematic synthesis of peptides on solid supports

All of the 181 possible overlapping hexapeptides as well as 179 octapeptides covering the amino acid sequence of human dihydrofolate reductase (hDHFR) were synthesized on polyethylene supports. The synthetic procedure of Geysen et al. (Geysen, H. M., Rodda, S. J., Mason, T. J., Tribbick, G., and Schoofs, P. G. (1987) J. Immunol. Methods 102, 259-274) was modified to obtain up to 100 nmol of peptide on each pin. Peptides constituting antigenic epitopes on hDHFR were identified by examining the binding of antibodies raised against both native and denatured hDHFR to these peptides by enzyme-linked immunosorbent assay. The peptides bound in a similar pattern to polyclonal antibodies against both native and denatured dihydrofolate reductase (DHFR). Six major epitopes were located corresponding to residues 27-33, 45-51, 67-74, 133-139, 153-158, and 176-181 using both hexapeptides and octapeptides. An additional epitope, constituting residues 14-21, was found by the use of octapeptides. Most of the epitopes are hydrophilic and reside largely in "loop" regions at the boundaries of secondary structural elements of hDHFR. This observation is consistent with our previous results which suggested that ligand binding at the active site of the enzyme can cause a dramatic reduction in antibody binding to DHFR due to conformational constraints in flexible loop regions in various parts of the molecule. The similarity of the immunogenic profiles of native versus denatured hDHFR indicates that the two forms of the antigen share the same amino acid sequence-specific epitopes. Competitive enzyme-linked immunosorbent assay showed that the binding of anti-hDHFR antiserum to both native and denatured hDHFR was inhibited by approximately 30% by the seven antigenic peptides, indicating that a significant proportion of the antibodies elicited by this enzyme is specific for short peptides. Besides revealing the antigenic structure of DHFR our results provide a rational basis for the design of mutant DHFRs to study the importance of loop residues in the conformational dynamics of the enzyme.

A sensitive high performance liquid chromatography microassay for bemoradan, a novel cardiotonic agent, in plasma/serum using a semi-automatic liquid/solid extraction sample preparation system--AASP

A high performance liquid chromatographic method for the measurement of bemoradan levels in plasma/serum is described. This method uses Varian's AASP (Varian Associates, Sunnyvale, CA, USA), a semi-automatic liquid/solid extraction sample preparation system. It requires only small volumes of plasma/serum samples (0.2-1 mL) and needs no organic solvent for sample preparation. The mean recovery of bemoradan at plasma or serum concentrations of 0.5-100 ng/mL is 82%. The assay has a detection limit of 0.5 ng/mL (when 1 mL of plasma/serum is used) and is linear in the concentration range 0.5-500 ng/mL.

Molecular and genetic organization of the suppressor of sable and minute (1) 1B region in Drosophila melanogaster

Recessive mutations at the suppressor of sable [su(s)] locus in Drosophila melanogaster result in suppression of second site mutations caused by insertions of the mobile element 412. In order to determine whether su(s) mutations might have other phenotypes, a saturation mapping of the su(s) region was carried out. The screen yielded 76 mutations that comprise ten genetic complementation groups ordered distal to proximal as follows: l(1)1Bh, l(1)1Bi, M(1)1B, su(s), l(1)1Bk, l(1)1Ca, mul, tw, l(1)lDa and brc. Twenty-three of the mutations are su(s) alleles, and all are suppressors of the 412-insertion-caused v1 allele. Although the screen could have detected su(s) mutations causing sex-specific dominant lethality or sterility as well as all types of recessive lethality or sterility, the only other phenotype observed was male sterility that is enhanced by cold temperature. This type of sterility is exhibited only by alleles induced by base-substitution-causing mutagens. Genetic functions of the poly(A+) messages transcribed from the su(s) microregion were identified by the reintroduction of cloned sequences into embryos by P element transformation. su(s) function has been attributed to a 5-kb message. The segment of DNA encoding only this 5-kb message rescues both the suppression and cold-sensitive male sterility phenotypes of su(s). Minute (1) 1B has been provisionally identified as encoding a 3.5-kb message; lethal (1)1Bi encodes a 1-kb message; and lethal (1)1Bk encodes a 4-kb message. The possible functions of su(s) and M(1)1B are discussed.

[Some difficult problems in the classification of acute leukemia]

The authors presented 5 cases of ANLL and 6 cases of ALL according to FAB classification and further classified them with leukemic cell morphology, cytochemistry and immunophenotyping. Five cases of them belonged to low grade peroxidase ANLL (LP-ANLL), 4 to hybrid acute leukemia (HAL) and 2 to acute undifferentiated leukemia (AUL). The importance of immunophenotyping of leukemic cells in classification of acute leukemia was emphasized and the criteria for diagnosis of LP-ANLL, HAL and AUL discussed. The authors are of the opinion that the diagnosis of these three kinds of acute leukemia is difficult and the prognosis is serious.

Effects of conversion of an invariant tryptophan residue to phenylalanine on the function of human dihydrofolate reductase

The binding site residue Trp-24 is conserved in all vertebrate and bacterial dihydrofolate reductases of known sequence. To determine its effects on enzyme properties, a Trp-24 to Phe-24 mutant (W-24-F) of human dihydrofolate reductase has been constructed by oligodeoxynucleotide site-directed mutagenesis. The W-24-F mutant enzyme appears to have a more open or flexible conformation as compared to the wild-type human dihydrofolate reductase on the basis of results of a number of studies. These studies include competitive ELISA using peptide-specific antibodies against human dihydrofolate reductase, thermal stability, and protease susceptibility studies of both mutant W-24-F and wild-type enzymes. It is concluded that Trp-24 is important for maintaining the structural integrity of the native enzymes. Changes in relative fluorescence quantum yield indicate that Trp-24 is buried and its fluorescence quenched relative to the other two tryptophan residues in the wild-type human reductase. Kinetic studies indicate that kcat values for W-24-F are increased in the pH range of 4.5-8.5 with a 5-fold increase at pH 7.5 as compared to the wild-type enzyme. However, the catalytic efficiency of W-24-F decreases rapidly as the pH is increased from 7.5 to 9.5. The Km values for dihydrofolate are also increased for W-24-F in the pH range of 4.5-9.5 with a 30-fold increase at pH 7.5, while the Km value for NADPH increases only ca. 1.4-fold at pH 7.5 as compared to the wild type.(ABSTRACT TRUNCATED AT 250 WORDS)