Internal jugular phlebectasia

Phlebectasia, defined as abnormal venous dilation, may occur in a number of different sites. Two cases with definite diagnosis of internal jugular phlebectasia were reported. The first case was a 6-year-old girl with a bulging mass on right neck for 3 years. Angiography and CT scan showed definite diagnosis, and the bulging mass was resected from the internal jugular vein (IJV). The second case was a 66-year-old female patient, also complained of a bulging mass on her right neck. Sonogram and CT scan also showed the same diagnosis. Because it did not bother the patient, she was just under close observation. From the three kinds of diagnostic modalities, we found sonography is an effective technique because of its clarity, safety and low cost.

Is IVP necessary in children with urinary tract infection?

A prospective study was conducted to determine the role of intravenous pyelography (IVP) in detecting the associated urinary tract anomalies in children with urinary tract infection (UTI). A total of 143 cases with confirmed UTI all received renal sonography (RS), voiding cystourethrography (VCUG) and IVP, to evaluate for G-U tract anomaly. Associated G-U tract anomalies were noted in 67 cases (46.85%). No single method was adequate in detecting all abnormalities. Based on the anomalies detected, we proposed and compared two different conditions in which IVP was required. In condition A, in which IVP was performed when abnormal finding were found in RS or VCUG, 67 of 143 cases with UTI (46.85%, 67/143) were required to have IVP, among them 32 cases yielded positive results and 35 cases negative results. Two cases of duplex collecting system (DCS) were found only on IVP would be completely undetected under this proposed condition. However, when IVP was recommended and performed at the time of high grade VUR in VCUG or any abnormality in RS (condition B), 43 of 143 patients (30%, 43/143) with UTI were required to undergo IVP, yielding abnormal findings in 30 cases (70%, 30/43) and normal findings in 13. This would leave four cases of DCS undetected, including the 2 detectable only by IVP plus 2 more that showed low grade VUR on VCUG. However, these 4 cases would not result in progressive renal damage in long-term follow up.(ABSTRACT TRUNCATED AT 250 WORDS)

Preliminary human trial of inactivated golden hamster kidney cell (GHKC) vaccine against haemorrhagic fever with renal syndrome (HFRS)

An inactivated golden hamster kidney cell culture (GHKC) vaccine against haemorrhagic fever with renal syndrome (HFRS) has been developed in recent years. A monovalent GHKC vaccine (lot 88-17) was prepared with L99 strain of the rat-type hantavirus, adapted in suckling mouse brain, cultivated in GHKC, and inactivated with 0.025% formalin, and a preliminary trial of the vaccine was carried out in a small number of human volunteers with the approval of the Ministry of Public Health, PRC, in order to identify safety and antibody response of the vaccine. Three inoculations were made on days 0, 7 and 28 respectively, by the intramuscular route with 1 ml vaccine each time for every volunteer. No obvious side effect was observed in vaccinees within 3 days after each inoculation. All 12 vaccinees (10 received three inoculations, and two received two inoculations of the vaccine) showed positive seroconversion of IgG antibody (by IFAT and ELISA) and neutralizing antibody (by enzyme focus reduction neutralization test, EFRNT), and 10 of them were still seropositive 180 and 360 days after the first inoculation. These results suggest that this vaccine would be safe for human use, and could effectively induce IgG and neutralizing antibody responses.

Atypical Kawasaki disease: report of two cases

Two cases of atypical Kawasaki disease are reported. Case 1 was a five-month-old male infant admitted to this hospital with a 10-day's history of high fever. On examination, he appeared ill-looking and only hepatomegaly was noted. Laboratory studies showed leukocytosis, thrombocytosis, elevated ESR and pleocytosis in CSF. He was treated as sepsis with meningitis. Sudden death occurred on the eighth day of admission, and left coronary artery aneurysm with thrombosis was noted at autopsy. Case 2 was a four-month-old male infant referred to our hospital with fever and cervical lymphadenopathy of 11 day's duration, and unresponsive to antibiotics. Skin rash had developed after oxacillin injection. Echocardiogram, performed on the third day of admission, disclosed a 5-8 mm aneurysm of the left coronary artery and a 4 mm aneurysm of the right coronary artery. Before a specific diagnostic test for Kawasaki disease becomes available, we suggest that a possible diagnosis of Kawasaki disease and echocardiographic evaluation should be considered in case of (1) presence of partial criteria of Kawasaki disease with thrombocytosis; and/or (2) young infants with prolonged unexplained fever.

Identification of amino acids modified by the bifunctional affinity label 5'-(p-(fluorosulfonyl)benzoyl)-8-azidoadenosine in the reduced coenzyme regulatory site of bovine liver glutamate dehydrogenase

Bovine liver glutamate dehydrogenase reacts with the bifunctional affinity label 5'-(p-(fluorosulfonyl)benzoyl)-8-azidoadenosine (5'-FSBAzA) in a two-step process: a dark reaction yielding about 0.5 mol of -SBAzA/mol of subunit by reaction through the fluorosulfonyl moiety, followed by photoactivation of the azido group whereby covalently bound -SBAzA becomes cross-linked to the enzyme [Dombrowski, K. E., & Colman, R. F. (1989) Arch. Biochem. Biophys. 275, 302-308]. We now report that the rate constant for the dark reaction is not reduced by ADP or GTP, but it is decreased 7-fold by 2 mM NADH and 40-fold by 2 mM NADH + 0.2 mM GTP, suggesting that 5'-FSBAzA reacts at the GTP-dependent NADH inhibitory site. The amino acid residues modified in each phase of the reaction have been identified. Modified enzyme was isolated after each reaction phase, carboxymethylated, and digested with trypsin, chymotrypsin, or thermolysin. The digests were fractionated by chromatography on a phenylboronate agarose column followed by HPLC. Gas-phase sequencing of the labeled peptides identified Tyr190 as the major amino acid which reacts with the fluorosulfonyl group; Lys143 was also modified but to a lesser extent. The predominant cross-link formed during photolysis is between modified Tyr190 and the peptide Leu475-Asp476-Leu477-Arg478, which is located near the C-terminus of the enzyme. Thus, 5'-FSBAzA is effective in identifying critical residues distant in the linear sequence, but close within the regulatory nucleotide site of glutamate dehydrogenase.

Anuria following reduction of a giant omphalocoele in a neonate: an unusual complication

Giant omphalocoele in the neonate is a challenging surgical emergency and requires individualized approaches to operative repair. Post-operative complications and associated congenital anomalies still continue to exert a high morbidity and mortality in spite of intensive and improved post-operative care. This case report describes an unusual mechanism which produced anuria in a neonate immediately after operative reduction of a giant omphalocoele. In retrospect, this complication was related to the unique anatomy of the neonate and the type of closure utilized.

Clinical implications of I-125 dosimetry of bone and bone-soft tissue interfaces

The dose to bone from I-125 photon interactions is expected to be approximately five times greater than the dose to soft tissue for the same photon fluence because of the dominance of the photoelectric effect. However, adverse clinical effects are not observed for I-125 implants near bone. Both the strong absorption of I-125 photons in bone and the narrowness (about 10 mu) of the high dose transition zone at a bone-soft tissue interface act to limit the volume of radiation sensitive tissue in the high dose region. Examples of calculated implant dose distributions in bone and in soft tissue cavities in bone are presented. Radiobiological measurements are consistent with the theoretical interface calculations. Calculation of the macroscopic dose distribution uses a recently measured radial dose function, while at the bone-soft tissue interface an analytic theory of the transition zone that is applicable to regular shaped cavities is used. Radiobiological experiments comparing cell survival for cells irradiated with 70 kvP X rays at Al-water and polystyrene-water interfaces are consistent with the transition zone calculations.

Inhibition of recA-mediated strand exchange by adducts of azacytosine-containing DNA and the EcoRII methylase

Wild type Escherichia coli cells containing elevated levels of DNA (cytosine-5)methyltransferases have increased sensitivity to the toxic effects of 5-azacytidine. The methyltransferases form tight binding complexes with azacytosine in DNA which could interfere with the recA recBCD repair pathway which is largely responsible for cell survival after treatment with the drug. We therefore determined if these complexes interfered with recA-mediated strand exchange in vitro. 32P-Labeled DNA fragments containing a single EcoRII site, with cytosine in the (-) strand replaced by 5-azacytosine, were prepared. We investigated the effect of the EcoRII methyltransferase on recA-mediated strand exchange with homologous M13 DNA by electrophoresis in agarose gels. In the absence of the methylase the rate and extent of strand exchange of azacytosine-containing DNA is the same as control DNA. In the presence of the methyltransferase strand exchange is inhibited, but some incorporation of duplexes into recA-single-stranded DNA (ssDNA) complexes still occurs. The formation of these complexes is dependent on the length of the fragment 3' to the methylase binding site on the strand complementary to the ssDNA. The greater the length the greater the number of complexes that form. S-Adenosyl-L-methionine, which enhances binding of the methyltransferase to azacytosine-containing DNA, causes an increase in the inhibition of strand exchange and an increase in the number of inactive complexes formed. The complexes can be dissociated with guanidinium chloride which denatures the methyltransferase and leads to release of the (+) strand. The (-) strand remains associated with the ssDNA. This result implies that a plectonemic joint is formed between recA-ssDNA complexes and azacytosine-containing DNA-methyltransferase complexes. However, branch migration in these complexes is inhibited. Denaturation of the methyltransferase allows branch migration to proceed to completion, releasing the (+) strand.

Collagen and elastin in the obstructed fetal bladder

Histological findings of muscle, collagen and elastin in obstructed fetal bladders were compared with those of age-matched controls. Muscle thickness was markedly increased, however, the relative collagen content in the muscle was decreased. The ratio of thick-to-thin collagen fibers was markedly increased as was the amount of elastin. These findings suggest that the ratio of thick collagen to elastin has an important role in determining the compliance of the obstructed fetal bladder.

Collagen and elastin in the normal fetal bladder

The development of muscle, collagen and elastic fibers was studied histologically in 15 human fetal bladder specimens. Muscle thickness progressively increased and the relative collagen content in the muscle decreased during gestation. The ratio of thick-to-thin collagen fibers also decreased, whereas elastic fibers increased. These findings document the normal process of maturation of the fetal bladder and serve as a basis for comparison with congenitally obstructed fetal bladders.

Effect of emitted bioenergy on biochemical functions of cells

The 3-5 microns infrared spectra of the external "Qi" generated by a "Qigong" master from his palm was measured using a III-V compound semiconductor InSb detector. It was found that certain Qigong master can emit two opposite kinds of "Qi": the "facilitating" (beneficial) and "inhibiting" (destroying) "Qi". During the facilitating "Qi" emission, large amount of infrared wave were detected by a temperature rise of the air in the vicinity. When the inhibiting "Qi" was emitted, the infrared wave was absorbed from the environment resulting in a cooling of the air. The temperature rise or drop possibly reflects the fact that the blood flow to the palm was increased or decreased by dilating or constricting the blood vessels through parasympathetic or sympathetic nerves. The biochemical effects of emitted "Qi" from the same Qigong master on the human fibroblast FS-4 were investigated. The facilitating "Qi" caused 1.8% increase of the cell growth in 24 hrs, 10-15% increase of DNA synthesis and 3-5% increase of protein synthesis of the cell in a 2-hr period; while inhibiting "Qi" caused 6% decrease of cell growth in a 24 hr period, 20-23% decrease of DNA synthesis and 35-48% of protein synthesis in a 2-hr period. In addition, we found that the respiration rate of boar sperm increased 12.5-13.0% after receiving 5 min exposure in facilitating "Qi," and a decrease to 45-48% by exposure to 2-min of inhibiting "Qi." The results could be attributed to the effects of emitted "Qi" or energy containing infrared light (wave) and possibly some other types of energy.

Subunit location and sequences of the cysteinyl peptides of pig heart NAD-dependent isocitrate dehydrogenase

Pig heart NAD-dependent isocitrate dehydrogenase has a subunit structure consisting of alpha 2 beta gamma, with the alpha subunit exhibiting a molecular weight of 39,000 and the beta and gamma each having molecular weights of 41,000. The amino-terminal sequences (33-35 residues) and the cysteinyl peptide sequences have now been determined by using subunits separated by chromatofocusing or isoelectric focusing and electroblotting. Displacement of the N-terminal sequence of the alpha subunit by 11-12 amino acids relative to that of the larger beta and gamma subunits reveals a 17 amino acid region of great similarity in which 10 residues are identical in all three subunits. The complete enzyme has 6.0 free SH groups per average subunit of 40,000 daltons, but yields 15 distinguishable cysteines in isolated tryptic peptides. Six distinct cysteines in sequenced peptides have been located in the alpha subunit. The beta and gamma subunits contain seven and five cysteines, respectively, with tryptic peptides containing three cysteines being common to the beta and gamma subunits. The three subunits appear to be closely related, but beta and gamma are more similar to each other than either is to the alpha subunit. The NAD-specific isocitrate dehydrogenase from pig heart has been shown to have 2 binding sites/enzyme tetramer for isocitrate, manganous ion, NAD+, and the allosteric activator ADP [Colman, R. F. (1983) Pept. Protein Rev. 1, 41-69]. It is proposed that the catalytically active tetrameric enzyme is organized as a dimer of dimers in which the alpha beta and alpha gamma dimers are nonidentical but functionally similar.

Endoscopic lithotripsy of gastric bezoars using a laser-ignited mini-explosive device

This paper reports the successful experiences of in vitro and in vivo studies on endoscopic fragmentation of gastric bezoars using a laser-ignited mini-explosive device. This new technique has been used clinically in 31 patients with gastric bezoars since January 1988. All patients were completely cured without any complication. The relationship between gastric bezoars and ulcers, and the technique of treatment were discussed.

[Kawasaki disease complicated with hemorrhagic enteritis mimicking intestinal obstruction: report of one case]

A 6-month-old little boy presented with fever and cervical lymphadenopathy for four days. On admission, he was found to have conjunctival congestion of both eyes, reddened and fissured lips, straw-berry tongue, macular rash at the trunk and erythematous change on the BCG injection site. The diagnosis of Kawasaki disease was made and aspirin therapy (100 mg/kg/day) was started. On the 3rd hospital day, he developed abdominal distention, jaundice, poor activity and tachypnea. Bowel sound was silent on auscultation. Nasogastric tube was inserted for decompression and bilious material was drained out continuously. In addition, bloody, mucoid stool passage was noted. An abdominal radiography revealed dilatation of the small bowel and paucity of the colon gases. On the abdominal ultrasound, hydrops of gallbladder, marked ascites and silent and dilated bowel loops were found. Despite of supportive care, abdominal symptoms persisted and condition deteriorated. Laparotomy was done on the following day. At operation, it was found that the patient developed severe petechia on the long segment of small intestine from 15cm distal to the Treitz ligament to ileocecal valve and some fibrin plagues on the terminal ileum at 25cm proximal to the ileocecal valve were also found.

Transdermal dual-controlled delivery of contraceptive drugs: formulation development, in vitro and in vivo evaluations, and clinical performance

Several transdermal contraceptive device (TCD) formulations were developed to provide a dual-controlled transdermal delivery of levonorgestrel (LN), a potent progestin, and 17 beta-estradiol (E2), a natural estrogen. Using a sensitive HPLC method, the in vitro release and skin permeation profiles of LN and E2 from various TCD formulations were simultaneously characterized in the hydrodynamically well-calibrated Valia-Chien skin permeation cells and both were found to follow zero-order kinetics. The rates of drug release and skin permeation were observed to vary significantly depending upon some formulation parameters. Six-month stability studies were performed on seven formulations at room and elevated temperatures (37 and 45 degrees C), and two (Formulations 4 and 5) were found to be acceptable, based on drug recovery, release rate, and skin permeation rate data. Judging from the 6-month accelerated stability studies, it is projected these two formulations will have shelf-life of at least 2 years. As a result of development of an efficient manufacturing process, Formulation 4 was selected for further evaluation. One-week primary skin irritation evaluation in 6 rabbits indicated that Formulation 4 is nonirritating, and it was thus selected for Phase I clinical bioavailability/dose proportionality studies in 12 healthy female volunteers of child-bearing age. Results of pharmacokinetic and pharmacodynamic analyses demonstrated that it is capable of achieving and maintaining a steady-state serum level of LN throughout the 3-week treatment period by weekly applications of one or two TCD patches (10 or 20 cm2). A dose proportionality was obtained in the serum drug levels, daily dose delivered, and contraception efficacy. An excellent correlation was obtained for the rates of transdermal delivery determined by the in vitro studies using human cadaver skin, the in vivo studies in rabbits, and the clinical studies in living subjects.

Protein metabolism during nutrient deprivation and refeeding of neonatal heart cells

Pathological conditions or nutrient deprivation in the heart cause an imbalance between rates of protein synthesis and degradation, often resulting in a severe depletion of cardiac protein. We used cultured neonatal rat heart cells, a model system exhibiting positive nitrogen balance, to examine the effects of 10 h of starvation on myocardial glucose and protein metabolism. Cellular capacity for glucose utilization was depressed after starvation, as evidenced by lower hexokinase and other glycolytic enzyme activities and a 21% decrease in glucose usage. A 21.0% decrease in protein synthetic rate and an increase in protein degradation rate combined to yield a 29.5% decrease in total cellular protein during starvation. Degradation rates increased 29.0, 46.7, and 59.6% in 2-, 24-, and 96-h prelabeled cells, respectively, indicating that lability increased with half-life of proteins. During refeeding of starved, cultured cells, at least three proteins were synthesized at a lower rate. At the same time, proteins with approximate molecular masses of 45, 84, 92, and 174 kDa exhibited increased synthesis.

Cysteinyl peptide labeled by 3-bromo-2-ketoglutarate in the active site of pig heart NAD+-dependent isocitrate dehydrogenase

The substrate affinity label 3-bromo-2-ketoglutarate (BrKG) reacts covalently with pig heart NAD+-specific isocitrate dehydrogenase with complete inactivation and incorporation of about 0.8 mol of reagent/mol of average enzyme subunit [Bednar, R.A., Hartman, F.C., & Colman, R.F. (1982) Biochemistry 21, 3681-3689]. Protection against inactivation is provided by isocitrate and Mn2+. We have now identified a critical modified peptide by comparison of the peptides labeled by BrKG at pH 6.1 in the absence and presence of isocitrate and Mn2+. Modified enzyme, isolated from unreacted BrKG, was incubated with [3H]NaBH4 to reduce the keto group of protein-bound 2-ketoglutarate and thereby introduce a radioactive tracer into the modified amino acid. Following carboxymethylation and digestion with trypsin, the specific modified peptide was isolated by reverse-phase HPLC, first in 0.1% trifluoroacetic acid with a gradient in acetonitrile and then in 20 mM ammonium acetate, pH 5.8, with an acetonitrile gradient. Gas-phase sequencing gave the modified peptide: Ser-Ala-X-Val-Pro-Val-Asp-Phe-Glu-Glu-Val-Val-Val-Ser-Ser-Asn-Ala-Asp-Gl u-Glu- Asp-Ile-Arg. The corresponding tryptic peptide that was isolated from unmodified enzyme yielded the same sequence except for (carboxymethyl)cysteine at position 3, suggesting that cysteine is the target of 3-bromo-2-ketoglutarate. Pig heart NAD+-dependent isocitrate dehydrogenase is composed of three distinct subunits (alpha, beta, and gamma) that can be separated by chromatofocusing in urea and identified by analytical gel isoelectric focusing. The peptide modified by 3-bromo-2-ketoglutarate, which is in or near the substrate site, is derived only from the separated gamma subunit.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of hormones and development on the expression of the rat 1,25-dihydroxyvitamin D3 receptor gene. Comparison with calbindin gene expression

We have used specific cDNAs to the rat vitamin D receptor (VDR) and to the mammalian vitamin D-dependent calcium-binding proteins (calbindin-D9k in intestine and calbindin-D28k in kidney) in order to obtain a better understanding of the regulation of the VDR gene and its relationship to calbindin gene expression. Hormonal regulation and development expression of the rat VDR gene were characterized by both Northern and slot blot analyses. Administration of 1,25-dihydroxyvitamin D3 (1,25(OH)2D3; 25 ng/day for 7 days) to vitamin D-deficient rats resulted in an increase in calbindin mRNA in intestine and kidney but no change in VDR mRNA in these tissues. Vitamin D-deficient rats responded to dexamethasone treatment (100 micrograms/100 g of body weight/day for 4 days) with a 2.5-fold increase in intestinal VDR mRNA which was accompanied by a 4-fold decrease in intestinal calbindin-D9k mRNA. Developmental studies indicated a pronounced increase in renal VDR mRNA and calbindin-D28k mRNA between birth and 1 week of age. In the intestine, an induction of VDR and calbindin-D9k gene expression was observed at a later time, during the 3rd postnatal week (the period of increased duodenal active transport of calcium). Taken collectively, our data indicate that in the adult rat, target tissue response to hormone is not modified by a corresponding alteration in new receptor synthesis. However, developmental studies indicate that the induction of 1,25(OH)2D3 receptor mRNA is correlated with the induction of calbindin gene expression. Our results also demonstrate that glucocorticoid administration can result in an alteration in intestinal calbindin and VDR gene expression.

Aspartyl peptide labeled by 2-(4-bromo-2,3-dioxobutylthio)adenosine 5'-diphosphate in the allosteric ADP site of pig heart NAD+-dependent isocitrate dehydrogenase

The nucleotide affinity label 2-(4-bromo-2,3-dioxobutylthio)adenosine 5'-diphosphate (2-BDB-TADP) reacts covalently with pig heart NAD+-dependent isocitrate dehydrogenase with a limiting value of 75% inactivation and loss of ADP activation concomitant with incorporation of about 1 mol of reagent/mol of average enzyme subunit (Huang, Y.-C., Bailey, J. M., and Colman, R. F. (1986) J. Biol. Chem. 251, 14100-14107). Complete protection against the functional changes is provided by ADP + Mn2+, and reagent incorporation is decreased to about 0.5 mol/mol of average enzyme subunit. We have now identified the critical modified peptide by comparison of the peptides labeled by 2-BDB-TADP at pH 6.8 in the absence and presence of ADP + Mn2+. After removal of excess reagent, modified enzyme was treated with [3H]NaBH4 to reduce the keto groups of the reagent and introduce a radioactive tracer into the reagent which is covalently linked to the protein. Following carboxymethylation and digestion with trypsin, the specific modified peptide was isolated using two successive high performance liquid chromatography steps: 1) 0.1% trifluoroacetic acid with an acetonitrile gradient; and 2) 20 mM ammonium acetate, pH 5.8, with an acetonitrile gradient. Gas phase sequencing gave the modified peptide Leu-Gly-Asp-Gly-Leu-Phe-Leu-Gln in which aspartic acid is the target of 2-BDB-TADP. Isolation of the corresponding tryptic peptide from unmodified enzyme yielded the sequence Leu-Gly-Asp-Gly-Leu-Phe-Leu-Gln-CmCys-CmCys-Lys. Isocitrate dehydrogenase is composed of three distinct subunits (alpha, beta, and gamma), separable by chromatofocusing in urea and identified by analytical gel isoelectric focusing. The evidence indicates that the specific peptide labeled by 2-BDB-TADP, which is at or near the ADP site, can be derived from the gamma subunit.

[The biological effect of sodium butyrate (NaBT) on SGC-7901 cells]

Changes of (Na+-K+)-ATPase activity, cAMP and fibronectin (FN) content and cell surface microvilli were studied cytochemically, immunocytochemically and scanning electron microscopically on human stomach Glandular carcinoma (SGC-7901) cells treated with NaBT(2.5 mM). It was found that NaBT not only inhibited cell growth but also remarkably decreased the activity of cell surface (Na+-K+)-ATPase of SGC-7901 cells. Note worthy was that, in comparison with the untreated tumor cells, the increase of the intensity of intracellular cAMP and FN immunofluorescence in NaBT-treated tumor cells was striking. Moreover, in contrast to untreated tumor cells, the cell surface of NaBT-treated tumor cells showed more smooth and fewer microvilli under SEM. That NaBT may induce differentiation of SGC-7901 cells through inhibition of (Na+-K+)-ATPase activity and modulation of cellular cAMP and FN content was discussed.

Transcriptional regulation and chromosomal assignment of the mammalian calbindin-D28k gene

To determine whether 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3] regulates transcription of the rat renal calbindin-D28k gene, the rate of calbindin-D28k mRNA synthesis was measured directly in nuclei using the in vitro nuclear transcription assay. Nuclei were prepared from kidneys of vitamin D-deficient rats at various times after a single ip injection of 1,25-(OH)2D3, and transcription was allowed to proceed in vitro in the presence of [32P]UTP for 30 min at 29 C, at which time the incorporation of UTP into trichloroacetic acid-precipitable material was optimal. Incorporation of UTP was decreased by 64.6% by alpha-amanitin, which selectively inhibits polymerase II. Purified [32P]RNA was analyzed for newly synthesized calbindin-D-28k gene transcripts by hybridization to calbindin-D28k cDNA immobilized on nitrocellulose filters. Using this assay we found that the first significant increase in calbindin-D28k gene transcription occurred at 1 h, and the peak of transcriptional activity occurred at 2 h. Within 12 h of 1,25-(OH)2D3 treatment, calbindin-D28k gene transcription returned to control levels. Using Northern blot analysis, a significant increase in calbindin-D RNA was first observed 2 h after hormone administration, reaching a maximum at 12 h. Renal calbindin-D28k protein levels are significantly increased by 3 h and reach a maximum value 48 h after hormone administration. Our results suggest that the early increase in renal calbindin-D28k may be due to transcriptional regulation. The long time lag between transcription and the peak of calbindin mRNA and calbindin protein accumulation may reflect the involvement of post-transcriptional mechanisms.(ABSTRACT TRUNCATED AT 250 WORDS)

Chronic torsion of the wandering spleen

Torsion of a wandering spleen can occasionally produce chronic disabling clinical findings that are mistaken for a variety of digestive disturbances. Since the clinical complaints are misleading, a correct and timely radiographic analysis can prevent an extensive but unnecessary pursuit of other more common conditions. Images of an ectopic, enlarged, disoriented spleen with a devitalized parenchyma and adherent pseudocapsule can quickly establish the diagnosis of chronic splenic torsion.

Effect of tidal volume and frequency on the temporal fall in lung compliance

In this study we have investigated how changes in respiratory frequency and tidal volume in anesthetized dogs affect the fall in dynamic compliance (Cdyn) that occurs with time after a hyperinflation. Results showed that increasing frequency [at controlled arterial (PaCO2)] PCO2 from 16 to 32 breaths/min had no effect on either the rate of fall or the magnitude of the fall up to 1 h after the hyperinflation. However, increasing the tidal volume from 300 to 750 ml abolished the fall in Cdyn from 10 to 50 min after the hyperinflation; the fall within the first 10 min remained unchanged. We also examined the effect of a simulated "hyperinflation" on the compliance of strips of parenchymal tissue in vitro. This result indicated that in the absence of surface forces, parenchymal tissue demonstrates a fall in compliance, which is complete within 10 min. Overall our findings are consistent with the hypothesis that the fall in Cdyn after hyperinflation is a two-phase process. The initial rapid fall in Cdyn (i.e., within 10 min) may simply represent a passive recovery process from the hyperinflation stress on the parenchymal tissue. The slower fall occurring after 10 min likely results from progressive increases in surface tension, and this increase can apparently be blocked by increases in tidal volume.

Modulation of rat calbindin-D28 gene expression by 1,25-dihydroxyvitamin D3 and dietary alteration

We have used a specific cDNA to the mammalian 28,000 Mr vitamin D-dependent calcium binding protein (calbindin-D28k) to study the regulation of the expression of this mRNA in rat kidney and brain. The effects of 1,25-dihydroxyvitamin D3 (1,25-(OH)2D3) and dietary alteration on genomic expression were characterized by both Northern and slot blot analysis. Administration of 1,25-(OH)2D3 for 7 days (25 ng/day) to vitamin D-deficient rats resulted in a marked increase in renal calbindin-DmRNA, renal calbindin, and serum calcium. When vitamin D-deficient rats were supplemented for 10 days with calcium (3% calcium gluconate in the water, 2% calcium in the diet) serum calcium levels were similar to the levels observed in the 1,25-(OH)2D3-treated rats. However, in the calcium-supplemented rats the levels of renal calbindin and renal calbindin mRNA were similar to the levels observed in the vitamin D-deficient rats, suggesting that calcium alone without vitamin D does not regulate renal calbindin gene expression in vivo. In dietary alteration studies in vitamin D-replete rats, renal calbindin protein and mRNA increased 2.5-fold in rats fed diets low in phosphate providing evidence that in the rat the nutritional induction of calbindin is accompanied by a corresponding alteration in the concentration of its specific mRNA. Under low dietary calcium conditions, the levels of renal calbindin protein and mRNA were similar to the levels observed in control rats, although 1,25-(OH)2D3 serum levels were markedly elevated, suggesting that factors in addition to 1,25-(OH)2D3 can modulate renal calbindin gene expression.(ABSTRACT TRUNCATED AT 250 WORDS)

Chromatography and electrophoresis of creatinine and other guanidino compounds

Chromatographic methods, in general, are considered as the definitive and reference procedure. The HPLC procedures reviewed all seem to provide improved and adequate specificity and sensitivity for CRN assay. The HPLC methods are relatively easy to use, have nearly complete recoveries (greater than or equal to 95%) and have good precision. The within- and between-day variations are often less than 4% [85,87,90,94-97,99]. Most of the methods developed [84,85,90,91,94,97,99] were tested for potential interference and the specificity for CRN was demonstrated. One important advantage of the HPLC method [85] is that the presence of an interfering substance in the biological sample can most likely be detected by its influence on the sharpness and resolution of the CRN peak. It is understandable that there are possibilities that other constituents in the biological sample may also be co-eluting with CRN and the investigator should carefully examine the chromatogram obtained for any sign of interference. Ginman and Colliss [107] reported that azathioprine, cyclosporin A, cefotaxime and prednisolone used in patients after renal transplant interfered with the HPLC assay: the results are 40% higher than those by Jaffe method. These interferences, however, were corrected with a slight modification of the HPLC conditions [107]. Because of the non-specificity associated with the Jaffe reaction, the results obtained from Jaffe-based assays often exceed those from HPLC methods [95,108,109]. Such overestimation would be especially significant when the serum CRN is in the normal range where small changes may be indicative of a significant change in a patient's renal function [95,111]. It appears that HPLC methods are the methods of choice for simultaneous analysis of endogenous guanidino compounds. Depending on the purpose of analysis, one would choose a particular type of method, e.g., one among those representative methods listed in Table 1. If one is interested in measuring MG and GSA levels in serum or plasma, then depending on the sensitivity requirement and available instrumentations, one could choose many method listed in Table 1. However, if one needs to measure AARG, ARG and ARA, in addition to MG and GSA, then method 4 in Table 1 would be more appropriate. If TAU is the compound of interest, then one of the methods 2,3,4,5, and 7 with an appropriate deproteinization procedure would be desirable.

Analysis of rat vitamin D-dependent calbindin-D28k gene expression

We report the use of a cloned cDNA for mammalian calbindin-D28k (28-kDa vitamin D-dependent calcium-binding protein) to study the expression of the rat calbindin gene. Tissue distribution studies, using Northern analysis, indicated that calbindin-D28k-mRNA is detected in rat kidney and brain but is not detected in rat intestine, testes, bone, pancreas, liver, lung, or skeletal muscle. Both rat kidney and brain contain three RNA species (1.9, 2.8, and 3.2 kilobase pairs). The regulation of the gene was characterized by both Northern and slot blot analysis. Hormonal regulation, developmental expression of calbindin-D28k-mRNA, and the effect of dietary alteration were examined. In the kidney all three species of mRNA were dependent on the presence of 1,25-dihydroxyvitamin D3 (1,25-(OH)2D3) for their induction. The time course of induction of renal calbindin-D28k-mRNA indicated that a significant increase in calbindin-D-mRNA was detectable as early as 2 h following a single injection of 1,25-(OH)2D3 (200 ng/100 g of body weight), reaching a maximum at 12 h. Unlike the kidney high levels of calbindin-D28k-mRNA were observed in the brain of vitamin D-deficient rats. The concentration of calbindin-D28k-mRNA in brain was unchanged after 1,25-(OH)2D3 administration. Developmental studies indicated that calbindin-D-mRNA in rat kidney and brain is present prior to birth but is developmentally regulated in a tissue-specific manner. The most pronounced changes in the abundance of renal calbindin-D28k-mRNA occur between birth and 1 week of age. Unlike the kidney a large increase in brain calbindin-D28k-mRNA occurs at a later time, between 1 and 2 weeks of age (the period of major synapse formation). In dietary alteration studies results of Northern blot analysis indicate that low dietary phosphorus results in increased calbindin-D-mRNA in kidney but not in brain. These studies represent the first analysis of the rat calbindin-D28k gene and its regulation in vivo. Our findings suggest that in rat kidney and brain there are significant differences both in the expression of the gene for calbindin-D28k and its regulation by 1,25-(OH)2D3.

Transdermal controlled administration of indomethacin. I. Enhancement of skin permeability

It was observed experimentally that indomethacin delivered in an aqueous suspension has a greater skin permeation rate in an ionized form than in a nonionized form. In this investigation, a matrix-type transdermal drug delivery system was developed to deliver indomethacin molecules in nonionized form. The skin permeation rate of nonionized indomethacin molecules from this system could be substantially improved by incorporating skin permeation enhancers, such as straight-chained alkanols, alkanoic acids, and esters. These enhancers form microreservoirs with indomethacin in the lipophilic silicone polymer matrix. By varying the alkyl chain length of alkanol, alkanoic acid, and its ester, the concentration of permeation enhancer, or the loading dose of indomethacin in the polymer matrix, the skin permeation rate of nonionized indomethacin molecules can be enhanced by as much as 30 times, which is almost sevenfold greater than the rate for ionized indomethacin molecules.

Evaluation of the effects of multiple-dose activated charcoal on the absorption of orally administered salicylate in a simulated toxic ingestion model

The effects of multiple-dose activated charcoal administration on the absorption of orally administered salicylate were evaluated in a simulated overdose model. Thirteen adult volunteers were each given 24 81-mg aspirin tablets during a control phase, and during three randomized treatment periods the volunteers received 50 g activated charcoal for one, two, or three doses (separated by four hours). The control phase and treatment periods were separated by a one-week interval. Urine was collected for 48 hours to determine percent total salicylate excretion. Ten subjects completed all four phases of the study. Mean +/- SD percent recovery of salicylate from urine was: control, 91.0 +/- 6.12; one-dose charcoal, 68.3 +/- 12.46; two-dose charcoal, 65.9 +/- 13.48; and three-dose charcoal, 49.2 +/- 12.48. Each charcoal treatment significantly lowered the absorption of aspirin as compared with the control (P less than .01). There was no significant difference between one-dose and two-dose charcoal regimens. There was a statistically significant decrease in salicylate absorption with the three-dose charcoal regimen as compared to one-dose and two-dose regimens (P less than .01). We conclude that activated charcoal is effective in inhibiting absorption of orally administered salicylate, in a small-dose aspirin ingestion model, with a three-dose multiple charcoal regimen being superior to either single-dose or two-dose regimens.

Segmental intestinal muscular thinning: a possible cause of intestinal obstruction in the newborn

Intestinal obstruction proximal to a transition zone without an interposed physical barrier usually indicates Hirschsprung disease. The authors report one case of focal small bowel muscular thinning just distal to a transition zone that produced clinical and radiographic findings that simulated long-segment Hirschsprung disease in a 2-day-old infant.

Effect of high-frequency ventilation on lung mechanics at high transpulmonary pressure

The different tidal volumes and frequencies of high-frequency ventilation (HFV) compared with conventional mechanical ventilation (CMV) may have different effects on lung mechanics. To test this hypothesis, we compared the effects of 3 h of HFV and CMV on total lung capacity (TLC), functional residual capacity (FRC), the shape of the pressure-volume (PV) curve (%V10), and dynamic compliance (Cdyn), as well as venous admixture and alveolar-arterial O2 gradient. We studied a total of 12 dogs at lung inflations equivalent to 15 cmH2O positive end-expiratory pressure (PEEP) (group I) and 8 dogs at lung inflations equivalent to 0 cmH2O PEEP (group II). For CMV, we used a standard-volume ventilator at a mean tidal volume of 13.8 ml/kg. For HFV, we used an oscillator-type ventilator at 15 Hz and an average tidal volume of 4.3 ml/kg. Our results showed that ventilation with 3 h of PEEP raised lung volume, and lung volumes on HFV were higher than those on CMV in both groups. Specifically, in group I, the volume during ventilation rose on both CMV (150 ml) and HFV (250 ml). These volume changes persisted beyond the ventilation period, such that TLC was unchanged on CMV but had risen 200 ml on HFV. FRC also rose 200 and 300 ml after HFV and CMV, respectively. In group II, the volume during ventilation fell 100 ml on CMV and rose slightly (40 ml) on HFV. TLC and FRC both tended to fall more on CMV.(ABSTRACT TRUNCATED AT 250 WORDS)

Bioavailability of three oral dosage forms of cisapride, a gastrointestinal stimulant agent

Relative bioavailability of the investigational gastrointestinal stimulant agent cisapride after oral administration was determined in healthy men. Treatments administered were (A) two 5-mg tablets; (B) one 10-mg tablet; (C) 10 mL of a 1-mg/mL suspension; and (D) 10 mL of a 1-mg/mL aqueous reference solution. The study had a randomized four-way, crossover design; drug administration was followed by a standard breakfast. Plasma cisapride concentrations in blood samples drawn over 48 hours were measured by high-performance liquid chromatography. Individual and mean values for bioavailability parameters were subjected to analysis of variance followed by multiple comparison testing. Time to maximum concentration was shortest after administration of the solution. There was a significant difference in mean peak plasma concentrations between treatment A (48.8 +/- 12.8 ng/mL) and treatment D (41.6 +/- 10.6 ng/mL), with treatment A producing a 17.3% higher peak concentration. No significant differences between treatments were found for area under the plasma concentration-time curve. The overall mean elimination half-life was 7.01 hours. The results of the study indicate that the tablet and suspension dosage forms of cisapride are bioequivalent to the reference solution.

Vitamin D-dependent calcium binding proteins in the kidney and intestine of the X-linked hypophosphatemic mouse: changes with age and responses to 1,25-dihydroxycholecalciferol

We have previously observed decreased intestinal 9 kilodalton (kd) vitamin D-dependent calcium binding protein (CaBP) and decreased calcium absorption in juvenile X-linked hypophosphatemic (Hyp) mice. The present studies were undertaken to examine whether the kidney CaBPs (9 kd and 28 kd) are also affected in young Hyp mice and to investigate the ability of 1,25-dihydroxycholecalciferol [1,25-(OH)2D3] to increase CaBP in the intestine and kidney. The 28 kd CaBP and the 9 kd CaBP were measured in the kidneys and the 9 kd CaBP in the intestines of normal and Hyp mice from 1 week to 40 weeks of age. At all times between 3 and 6 weeks, intestinal CaBP in Hyp mice was decreased by more than 50% (P less than 0.005-0.001) and no significant decrease was present in the adult Hyp mice (12 and 40 weeks of age). By contrast, both kidney CaBPs were decreased only slightly in young Hyp mice. Between 1 and 6 weeks of age, the 9 kd CaBP in Hyp mice was 82% +/- 4% of control (P less than 0.001) and the 28 kd protein was 89% +/- 3% of control (P less than 0.001). Minipumps containing 1,25-(OH)2D3 or vehicle were implanted in 4-week and 13-week-old Hyp mice for 3 days to provide a dose of 0.12 micrograms/kg mouse X day. The 9 kd CaBP was increased approximately 3-fold (P less than 0.001) by 1,25-(OH)2D3 in the intestines of Hyp mice at both ages. The 9 kd kidney CaBP in Hyp mice also was increased by 1,25-(OH)2D3 treatment at both ages, but only by 33-52%. The 28 kd CaBP in the kidney was not affected by 1,25-(OH)2D3 treatment of Hyp mice at either age. We conclude that (9 kd and 28 kd) CaBPs levels in both intestine and kidney are decreased in juvenile Hyp mice although to much different degrees. The administration of 1,25-(OH)2D3 to Hyp mice increases the 9 kd CaBP in both intestine and kidneys, whereas the renal 28 kd CaBP is unaffected.

Pharmacokinetics and dose proportionality of domperidone in healthy volunteers

Domperidone is a potent gastrokinetic agent and antinauseant currently undergoing clinical trials in the United States. The bioequivalence of 20 mg of domperidone given as free-base tablets and maleate salt tablets, and the bioavailability of base and maleate tablets relative to a solution, were studied in 21 fasting men using a crossover design. Plasma samples collected for up to 48 hours were analyzed for domperidone levels, using a sensitive and specific radioimmunoassay (RIA). The absorption of domperidone was very rapid, with mean peak plasma concentration (Cmax) values of 18.8, 15.0, and 20.7 ng/mL attained at 0.9, 1.2, and 0.6 hours after the administration of base tablet, maleate tablet, and solution, respectively. The mean elimination half-life (t1/2) ranged from 12.6 to 16.0 hours. The mean oral clearance (CL/F) after the solution dose was 4,735 +/- 2,017 mL/min and the mean apparent volume of distribution (Vd/F) was 6,272 +/- 5,100 L, indicating an extensive distribution of domperidone in the body. The area under the plasma concentration-time curve (AUC) data demonstrated bioequivalence of base and maleate tablets. The relative bioavailability for base tablet and maleate tablet was 107 +/- 50% and 116 +/- 47%, respectively, of that of the solution. Dose proportionality of domperidone was also studied in 12 subjects at solution doses of 10, 20, and 40 mg. Linear correlations between the dose and Cmax and AUC values were observed. Mean CL/F remained relatively constant after doses of 10, 20, and 40 mg (5,255 +/- 3,159, 4,842 +/- 1,774, and 4,380 +/- 1,289 mL/min, respectively), indicating linear pharmacokinetics of domperidone over the dose range studied.

[Gastric cancer treated by hematoporphyrin derivative(HPD)-laser--histopathological study of 10 gastrectomy specimens]

10 patients with gastric carcinoma treated by HPD-laser preoperatively are reported. The gastric lesions were irradiated with laser beam delivered by a quartz fibre through the fiberoptic gastroscope 48-72 hours after intravenous injection of HPD (5.0 mg/kg) about 2 weeks before operation. In the resected specimens, the histological changes following HPD-laser therapy were studied. The cancer cells in the irradiated areas showed degeneration and necrosis in varying degrees. Because of the fact that the light spots were small and the penetration not deep enough, the cancer cells beyond the irradiated area and those infiltrating more deeply or beyond the gastric wall did not show any evident changes while metastatic cancers in the lymph nodes showed no changes at all. These facts may suggest that the HPD-laser therapy should not be used as the main therapeutic method to replace operation, radiotherapy or chemotherapy for gastric cancers in either advanced or early stage.

Inactivation of NAD-dependent isocitrate dehydrogenase by affinity labeling of the allosteric ADP site by 2-(4-bromo-2,3-dioxobutylthio)adenosine 5'-diphosphate

A new reactive ADP analogue has been synthesized: 2-(4-bromo-2,3-dioxobutylthio)adenosine 5'-diphosphate (2-BDB-TADP). Reaction of ADP with m-chloroperoxybenzoic acid gave ADP 1-oxide, which was treated with NaOH, followed by reaction with carbon disulfide to yield 2-thioadenosine 5'-diphosphate. The final product was synthesized by condensation of 2-thioadenosine 5'-diphosphate with 1,4-dibromobutanedione. Reaction of pig heart NAD-specific isocitrate dehydrogenase with this nucleotide analogue (0.4 mM) causes a time-dependent loss of activity to a limiting value of 75% inactivation. The rate constant for inactivation exhibits a nonlinear dependence on the concentration of 2-BDB-TADP, with kmax = 0.021 min-1 and KI = 0.067 mM. Complete protection against inactivation by 0.2 mM 2-BDB-TADP is provided by ADP + Mn2+, but not by Mn2+ alone, isocitrate, alpha-ketoglutarate, or NAD. Incorporation of 2-BDB-TADP is proportional to the extent of inactivation, reaching 1 mol of reagent/mol of enzyme subunit when the enzyme is maximally inactivated. However, when inactivation is totally prevented by incubation with 2-BDB-TADP in the presence of ADP and Mn2+, 0.5 mol of reagent/mol of subunit is still incorporated, suggesting that inactivation may be attributed to 0.5 mol of reagent/mol of average subunit. In the native enzyme, the Km for total isocitrate is 1.8 mM and is decreased 6-fold to 0.3 mM in the presence of 1 mM ADP, whereas in the modified enzyme, with 25% residual activity, the Km for total isocitrate is about the same in the absence (2.0 mM) or presence (1.8 mM) of ADP. These results indicate that 2-BDB-TADP acts as an affinity label of the ADP allosteric site of NAD-dependent isocitrate dehydrogenase.

Pharmacokinetics and dose proportionality of ketoconazole in normal volunteers

Ketoconazole is an orally effective, broad-spectrum, systemic antifungal agent. The pharmacokinetics and bioavailability of ketoconazole given as a 200-mg single dose in a tablet, suspension, or solution were studied in 24 fasting healthy males by using a crossover design. Levels of ketoconazole in plasma were determined for up to 48 h by a sensitive reverse-phase high-performance liquid chromatography method. The absorption of ketoconazole was rapid, with mean maximum concentrations of the drug in plasma of 4.2, 5.0, and 6.2 micrograms/ml attained at 1.7, 1.2, and 1.0 h, respectively, after administration of the tablet, suspension, and solution, respectively. The mean distribution and elimination half-life values were 1.5 to 1.7 and 7.5 to 7.9 h, respectively. The mean oral clearance of the solution dose was 209 (+/- 82.9 [standard deviation]) ml/min, and the mean apparent volume of distribution was 88.31 (+/- 68.72) liters. The relative bioavailabilities for the tablet and suspension were 81.2 (+/- 33.5) and 89.0 (+/- 23.1)%, respectively, of that of the solution. The data indicated the bioequivalence of the tablet to the suspension and of the suspension of the solution. Dose proportionality of ketoconazole was also studied in 12 volunteers after they received solution doses of 200, 400, and 800 mg. Linear correlations between the dose and the maximum concentration of the drug in plasma, the time to the maximum concentration, and the area under the concentration-time curve were observed. However, the increase in the area under the curve was more than proportional to the dose given. The levels in plasma seemed to decay at a lower rate after 400- and 800-mg doses. The mean oral clearance decreased from 244.9 to 123.6 and 80.0 ml/min, respectively, as the dose increased from 200 to 400 and 800 mg. The apparent dose-dependent kinetics may have been due to the presystemic elimination and capacity-limited hepatic metabolism which become saturated at higher doses.

Affinity labeling of the allosteric ADP activation site of NAD-dependent isocitrate dehydrogenase by 6-(4-bromo-2,3-dioxobutyl)thioadenosine 5'-diphosphate

Pig heart NAD-dependent isocitrate dehydrogenase is allosterically activated by ADP which reduces the Km of isocitrate. The new ADP analogue 6-(4-bromo-2,3-dioxobutyl)thioadenosine 5'-diphosphate (BDB-TADP) reacts irreversibly with the enzyme at pH 6.1 and 25 degrees C, causing a rapid loss of the ability of ADP to increase the initial velocity of assays conducted at low isocitrate concentrations and a slower inactivation measured using saturating isocitrate concentrations. The rate constant for loss of ADP activation exhibits a nonlinear dependence on BDB-TADP concentration; in the presence of 0.2 mM MnSO4, KI for the reversible enzyme-reagent complex is 0.069 mM with kmax at saturating reagent concentrations equal to 0.031 min-1. For reaction at the site causing overall inactivation, KI for the initial reversible enzyme-reagent complex is estimated to be 0.018 mM with kmax = 0.0083 min-1 in the presence of 0.2 mM MnSO4. Total protection against both reactions is provided by 1 mM ADP plus 0.2 mM MnSO4 or by 0.1 mM ADP plus 0.2 mM MnSO4 plus 0.2 mM isocitrate, but not by NAD, ATP, or ADP plus EDTA. The BDB-TADP thus appears to modify two distinct metal-dependent ADP-binding sites. Incubation of isocitrate dehydrogenase with 0.14 mM BDB-[beta-32P]TADP at pH 6.1 in the presence of 0.2 mM MnSO4 results in incorporation of 0.81 mol of reagent/mol of average subunit when the ADP activation is completely lost and the enzyme is 68% inactivated. The time-dependent incorporation is consistent with the postulate that covalent reaction of 0.5 mol of BDB-TADP/mol of average enzyme subunit causes complete loss of ADP activation, while reaction with another 0.5 mol of BDB-TADP would lead to total inactivation. The enzyme is composed of three distinct subunits in the approximate ratio 2 alpha:1 beta:1 gamma. The distribution of BDB-[beta-32P]TADP incorporated into modified enzyme is 63:30:7% for alpha:beta:gamma throughout the course of the reaction. These results indicate the 6-(4-bromo-2,3-dioxobutyl)thioadenosine 5'-diphosphate functions as an affinity label of two types of potential metal-dependent ADP sites of NAD-dependent isocitrate dehydrogenase and that these allosteric sites are present on two (alpha and beta) of the enzyme's three types of subunits.

6-[(4-bromo-2,3-dioxobutyl)thio]-6-deaminoadenosine 5'-monophosphate and 5'-diphosphate: new affinity labels for purine nucleotide sites in proteins

Two new adenine nucleotide analogues have been synthesized and characterized: 6-[(4-bromo-2,3-dioxobutyl)thio]-6-deaminoadenosine 5'-monophosphate and 5'-diphosphate. The bromoketo and dioxobutyl moieties have the ability to react with the nucleophilic side chains of several amino acids, as well as with arginine. 6-[(4-Bromo-2,3-dioxobutyl)thio]-6-deaminoadenosine 5'-monophosphate reacts irreversibly with rabbit muscle pyruvate kinase, causing inactivation. Addition of ADP to the reaction mixture (in the presence of Mg2+) markedly decreases the rate of inactivation. Pig heart NAD-dependent isocitrate dehydrogenase is allosterically activated by ADP, which reduces the Km for isocitrate. 6-[(4-Bromo-2,3-dioxobutyl)thio]-6-deaminoadenosine 5'-diphosphate reacts irreversibly with isocitrate dehydrogenase, causing, rapidly, a loss of the ability of ADP to increase the initial velocity of assays conducted at low isocitrate concentrations and, more slowly, inactivation. Addition of ADP to the reaction mixture (in the presence of Mn2+) protects this enzyme against the loss of allosteric activation. It is proposed that the 6-[(4-bromo-2,3-dioxobutyl)thio]-6-deaminoadenine nucleotides react at the active site of pyruvate kinase and at the ADP activating site of isocitrate dehydrogenase and that these compounds may have general applicability as affinity labels of catalytic and regulatory adenine nucleotide sites in proteins.

Creatinine X--potential nonrenal elimination of endogenous creatinine in humans and its clinical significance

From an analysis of the data in the literature for creatinine renal clearance and steady-state serum level and published equations, we estimated a wide range (1.4-76.3 ml/min) of nonrenal clearances of endogenous creatinine. Nonrenal clearance might contribute 0-34% of the total body clearance in patients with normal renal function. This paper discusses the clinical significance of the potential overestimation of renal function by using published nomograms or equations (derived from a direct inverse relationship between the creatinine clearance and steady-state level or the assumption of nonexistence of nonrenal elimination of creatinine) for indirect estimation of creatinine clearances from serum creatinine levels.

Pharmacokinetics of chlorpheniramine after intravenous and oral administration in normal adults

Plasma and urinary levels of chlorpheniramine (CPM) and its 2 demethylated metabolites were measured by HPLC after i.v. and oral dosing. In 5 mg (maleate) i.v. bolus studies in 2 subjects, plasma CPM levels were fitted to triexponential equations with terminal half-lives (t 1/1) of 23 and 22 h and area of 3.6 and 3.21/kg, respectively. Intravenous data predicted hepatic blood extraction ratios for the 2 subjects to be 0.06 and 0,07, respectively. Absolute bioavailability from oral solution (10 mg) was 59 and 34%, and from tablets (8 mg) 44 and 25%, respectively, indicating extensive gut first-pass metabolism. Mean t 1/2 from 7 oral fasting studies in 5 subjects was 28 h (19-43 h). Mean absorption lag time was 0.7 h (0.4-1.3 h), and mean peak time was 2.8 h (2-4 h). In 2 subjects, 6 mg solutions were given every 12 h for 9 doses; good correlation between single and multiple dose kinetics was found. Significant accumulation was demonstrated in simulation studies with frequent daily dosing. Estimated accumulation ratios vary from 4.1 to 9.4 (mean 6.5). The t 1/2 from urinary data (collected for 12 days) was consistent with plasma data. The above results suggest the need to reexamine the current practice of frequent daily dosing and the use of sustained or controlled release dosage forms of this drug. The possible cause of reduced plasma clearance of CPM in renal patients is discussed.