Carbon Isotopic Fractionation Does Not Occur during Dark Respiration in C3 and C4 Plants

The magnitude of possible carbon isotopic fractionation during dark respiration was investigated with isolated mesophyll cells from mature leaves of common bean (Phaseolus vulgaris L.), a C3 plant, and corn (Zea mays L.), a C4 plant. Mesophyll protoplasts were extracted from greenhouse-grown leaves and incubated in culture solutions containing different carbohydrate substrates (fructose, glucose, and sucrose) with known [delta]13C values. The CO2 produced by protoplasts after incubation in the dark was collected, purified, and analyzed for its carbon isotope ratio. From observations of the isotope ratios of the substrate and respired CO2, we calculated the carbon isotope discrimination associated with metabolism of each of these substrates. In eight of the 10 treatment combinations, the carbon isotope ratio discrimination was not significantly different from 0. In the remaining two treatment combinations, the carbon isotope ratio discrimination was 1[per mille (thousand) sign]. From these results, we conclude that there is no significant carbon isotopic discrimination during mitochondrial dark respiration when fructase, glucose, or sucrose are used as respiratory substrates.

The role of endoscopic retrograde cholangiopancreatography in management of patients recovering from acute biliary pancreatitis in the laparoscopic era

BACKGROUND

Traditionally an episode of acute biliary pancreatitis (ABP) is an indication for direct imaging of the biliary tree. The optimal approach may vary according to local expertise, and endoscopic retrograde cholangiopancreatography (ERCP) is the most common. The fact that the incidence of choledocholithiasis in patients recovering from ABP varies between 3 and 33% raises a question about the necessity of visualizing the biliary tree in all patients recovering from ABP.

METHODS

In order to evaluate this policy, we reviewed 48 ERCPs performed on patients recovering from ABP who were scheduled for laparoscopic cholecystectomy (LC). We checked the correlations between ERCP findings and the severity of pancreatitis, biochemistry values (which were sampled during the acute phase), and ultrasonographic (US) findings.

RESULTS

The ERCP demonstrated common bile duct (CBD) stones in 11 (22.9%) patients. US finding of a dilated CBD and maximal aspartate transaminase (AST) values higher than 90 units/l were significantly correlated with CBD stones (a relative risk [RR] of 2.95 with a 95% confidence interval [CI] for a dilated CBD and RR of 3.89 with a 95% CI of 1.18-12.80 for an AST value higher than 90 units/l). No other parameters were significantly correlated with CBD stones.

CONCLUSION

We, therefore, recommend performing a preoperative ERCP only on patients who present with an ultrasonographic finding of CBD dilatation. The correlation to high AST is still to be proven.

[Infective factors of adult secretory otitis media]

There were histories of the upper expiratory tract infection in 49 out of 86 cases in adult secretory otitis media (SOM). Among them, thirty two cases were administrated antibiotics a week ago when the effusions were collected. The patient's Eustachian tubes in twenty nine cases were clinically ventilated. The endotoxins were positive in 39 out of 86 specimen tested with limulus assay, among these specimen, bacteria were cultured from 11 specimen. The data exibited that the appearance of the SOM is related to the existence of the infective factors in the middle ear cavity. The upper expiratory tract infection before the onset of the middle ear effusions is one of the important causes inducing the disease. The lower rate of bacteria culture than that of endotoxins is related with the administration of antibiotics before the onset of the disease. The administration of antibiotics in the treatment of the middle ear effusions will help to elimilate bacteria in the cavity of the middle ear effusions, improve the ventilating function of the Eustachian tube and make the effusions turn to disappearance.

Mechanisms for the coordination of intercellular calcium signaling in insulin-secreting cells

Insulin-mediated increases in cytosolic calcium are synchronized among the cells in a pancreatic islet, and result in pulsatile secretion of insulin. Pancreatic beta cells express the gap junction protein connexin43 and are functionally coupled, making gap junctional communication a likely mechanism for the synchronization of calcium transients among islet cells. To define the mechanism by which pancreatic islet cells coordinate calcium responses, we studied mechanically-induced intercellular calcium waves in the communication-deficient rat insulinoma cell line RINm5f, and in RINm5f cells transfected with the gap junction protein connexin43. Both RINm5f and RINm5f cells transfected with connexin43 propagated calcium waves that required release of calcium from intracellular stores, did not involve gap junctional communication, and appeared to be mediated by autocrine activity of secreted ATP acting on P2U purinergic receptors. Connexin43 transfectants also propagated calcium waves that required gap junctional communication and influx of extracellular calcium through voltage-gated calcium channels. Gap junction-dependent intercellular calcium waves were inhibited by preventing plasma membrane depolarization. These studies demonstrate two distinct pathways by which insulin-secreting cells can coordinate cytosolic calcium rises, and show that it is by ionic traffic that gap junctions synchronize calcium-dependent events in these cells.

High-level secretion of two antibody single chain Fv fragments by Pichia pastoris

The diagnostic and therapeutic applications of antibody single-chain Fv (sFv) fragments often require large amounts of protein that can be problematic and expensive to obtain. Here we report the secretion of two sFv fragments by the yeast Pichia pastoris at levels up to 250 mg/l. Soluble sFv fragments were purified from culture supernatants in one step by affinity or metal-chelating chromatography, and were indistinguishable from their bacterially expressed counterparts in terms of affinity. Secretion of functional sFv fragments by Pichia pastoris provides a low cost, high yield alternative to current sFv expression systems.

[Endovascular treatment of brain arteriovenous malformation]

Eighteen patients with arteriovenous malformations (AVMs) of the brain were treated with endovascular techniques between 1993 and 1996. The following angiograms showed complete obliteration of the nidus in 2 patients, 70%-90% reduction in nidus volume in 5, 50%-70% reduction in 3, and < 50% in the remaining 3. Two patients suffered from moderate neurologic deficits after embolization. One week after the treatment, 4 patients with superficial AVMs underwent surgery, and 2 with deep-situated AVMs received gamma-knife therapy. 14 patients were followed up, suffered from more frequent epilepsy, and 1 had intracranial haemorrhage 6 months after embolization. A few AVMs can be cured by endovascular embolization. In regard to some large AVMs or AVMs situated at important functional areas, embolization can facilitate surgery and radiotherapy afterwards.

Pulse oxymetry evaluation of oxygen saturation in the upper extremity with an arteriovenous fistula before and during hemodialysis

We noticed that some patients with arteriovenous (AV) fistula on chronic hemodialysis experience pain in the limb with the fistula a short time after being connected to the dialysis machine. We postulated that the pain is caused by relative ischemia and therefore performed this study to determine whether oxygen saturation (SaO2) of the extremities with AV fistula decreases during hemodialysis. Seventy-two patients with a side-to-side primary AV fistula were evaluated by pulse oxymetry. SaO2 was measured before hemodialysis and 20 minutes after initiation of dialysis. The contralateral arm served as a control. In 48 patients, SaO2 difference between the arms of each patient before hemodialysis was less than 4%. SaO2 values of this group of patients did not change significantly 20 minutes after initiation of dialysis. In 24 patients, SaO2 differences between the hands of each patient before hemodialysis were 4% or more. In this group of patients, SaO2 values of the hands with the AV fistula decreased significantly 20 minutes after hemodialysis from a mean of 90.85 +/- 2.84% to 81.60 +/- 3.94 (P < 0.001). SaO2 remained unchanged in the contralateral arm. Nine patients in this group complained of pain and change in sensation in the arm with the fistula during hemodialysis. One patient complained of severe pain in the arm with the fistula before hemodialysis, and SaO2 was unmeasurable. We conclude that, in some patients, SaO2 of the arm with the AV fistula decreases only during hemodialysis. This phenomenon may be symptomatic. A predialysis SaO2 difference of 4% or more between the arms predicts decreased SaO2 of the arm with the AV fistula during hemodialysis.

Elderly migration: household versus individual approaches

"This paper employs a household approach to elderly migration analyses and compares it with the traditional individual approach. The first part of the paper develops some concepts about household mobility and relates them to individual mobility. It then compares the two mobility measurements in a case study using the Public Use Microdata Sample (PUMS) from the 1990 [U.S.] Census. The results show that the mean household size for the elderly moving together tends to be smaller than that for elderly stayers. It also demonstrates the utility of the household approach on profiling elderly movers' living arrangement choices. The second part of the paper calibrates a set of discrete choice models based on the household and individual approaches."

Spectral and chromatographic properties of 2-methoxyphenylmetyrapone and its potential metabolites

In the search for new metyrapone derivatives as radioligands for the functional diagnosis of adrenal pathology, 2-methoxyphenylmetyrapone [2-MPMP, 1-(2-methoxyphenyl)-2-methyl-2-(3-pyridyl)-1-propanone] (1), and related 2-substituted phenylmetyrapone derivatives, have been separated as potent inhibitors of adrenal 11 beta-hydroxylase, with high affinity for adrenal mitochondrial binding sites. Surprisingly, 2-[11C]MPMP showed a rapid loss of the radioactive label, which prompted investigation of its metabolism. Synthetic 2-MPMP (1) and its seven potential metabolites (2-8) have been identified spectroscopically (1H- and 13C-NMR and mass spectrometry) and further characterised by chromatography (TLC and gradient reversed-phase HPLC). Chromatographic and mass analysis of urinary extracts from rats dosed with 2-MPMP have confirmed the major metabolites as 2-hydroxyphenylmetyrapone (2-OHPMP), 2) and its N-oxide (2-OHPMP-NO, 6), which are present predominantly as conjugates.

Bacterial expression and characterization of an anti-desipramine single-chain antibody fragment

Tricyclic antidepressant toxicity is a leading cause of death from intentional drug overdose. Monoclonal antibody Fab' fragments specific for the tricyclic antidepressant, desipramine, reverse acute drug toxicity but may themselves have adverse effects at therapeutic doses. To evaluate the characteristics of smaller antibody fragments, we cloned, expressed and characterized a 26 kD single chain Fv fragment (G5-sFv). A DNA sequence encoding VH-linker-V1 was constructed from hybridoma mRNA encoding a high affinity monoclonal desipramine specific IgG1 and expressed in E. coli. G5-sFv was produced at high levels as insoluble inclusion bodies. Single chain Fv was solubilized, folded in a redox buffer and affinity purified on desipramine-Sepharose. The affinity of G5-sFv for desipramine was similar to that of the corresponding monoclonal Fab' as measured by surface plasmon resonance (Fab' 5.5 +/- 0.5 x 10(8) M-1, sFv 2.3 +/- 0.5 x 10(8) M-1). G5-sFv administered to rats after a tracer dose of 3H-desipramine produced rapid and marked redistribution of drug from tissues into serum. G5-sFv was stable at 4 C for greater than 6 months but lost activity at higher temperatures. We conclude that desipramine-specific-single chain Fv expressed in E. coli retains the affinity of the parent antibody for desipramine. The pharmacokinetic effect of G5-sFv on desipramine distribution suggests that it may be useful as an antidote for desipramine overdose.

Inflammatory cytokines in animal health and disease

Inflammatory cytokines, including tumor necrosis factor (TNF), interleukin-1 (IL-1), IL-6 and IL-8, are rapidly induced early in a disease or injury process. They mediate and modulate myriad healing processes but, if overexpressed, may exacerbate the severity of a disease condition. In order to test this concept and to establish a foundation for the role of inflammatory cytokines in the pathogenesis of gram-negative bacterial infections in the respiratory tract of animals, the patterns of inflammatory cytokine expression were determined in experimental porcine pleuropneumonia. We observed that IL-1 and IL-6, but not TNF, were rapidly and dramatically elevated in the lavage fluid of the lung within 24 h of infection. The increased levels of IL-1 might contribute to increased severity of disease, but elevated IL-6 levels were consistent with a protective acute phase response. Additional studies were performed to examine the hypothesis that IL-4 expression later in infection might be involved in turning off the inflammatory response and promoting an antigen-specific humoral immune response. Interleukin-4 efficiently suppressed inflammatory cytokine production in alveolar macrophages. Its expression was induced in peripheral blood mononuclear cells by TNF, IL-4, and by reexposure to a specific antigen. To obtain the maximum amount of information on the role of inflammatory cytokines in animals of veterinary significance it will be useful to perform studies in species such that evolutionary relatedness will allow widespread application of the findings. Furthermore, the variety of molecules involved in inflammatory cytokine regulation will require much more extensive investigations of the relevant enzymes, inhibitors and receptors in veterinary species. Finally, the complexity and redundancy of immune defenses in animals mean that attempts to modulate health status through manipulation of inflammatory cytokines must be performed with caution and that a multiplicity of processes will be affected.

Prederivatization and high-performance liquid chromatographic analysis of alkaloids of bulbs of Fritillaria

A method of prederivatization and HPLC with UV detection was developed for the simultaneous analysis of five major steroidal alkaloids of the Fritillaria species: verticine, verticinone, isoverticine, ebeiedine, and ebeiedinone. Derivatization was carried out by esterification of the hydroxyl-containing Fritillaria alkaloids to the corresponding naphthoates with 1-naphthoyl chloride. Reaction conditions were optimized and the yields of the derivatization were between 94 and 100% for all test alkaloids. Derivatized alkaloids were characterized by mass spectrometry and HPLC-MS. The validated HPLC-UV method demonstrated linear UV response at the sampling ranges used, and a test limit of 1 microgram/mL was determined for all analytes. This analytical method is simple, convenient, and readily reproducible. The developed method was applied to the analysis of the major pharmacologically active alkaloids in three medicinally used Fritillaria species: F. cirrhosa, F. thunbergii, and F. hupehensis. Five major Fritillaria alkaloids were simultaneously analyzed qualitatively and quantitatively from crude extracts of each of these herbs.

Is male gender a risk factor for conversion of laparoscopic into open cholecystectomy?

BACKGROUND

Based on a clinical observation that the conversion rate of laparoscopic cholecystectomy (LC) to open cholecystectomy (OC) is higher in males, we decided to review our records and to verify whether a significant difference in conversion rates exists between sexes.

METHODS

A retrospective study on conversion rates of elective laparoscopic cholecystectomy (LC) into open cholecystectomy (LC) in relation to gender was carried out in 329 patients: 267 females and 62 males.

RESULTS

Our data revealed that the probability of conversion is fivefold greater in males than females, 21% vs 4.5%, respectively (p = 0.0001). We attribute this striking difference to significantly more adhesions p = 0.0002) and anatomical difficulties (p = 0.003) in males during LC, leading to conversion.

CONCLUSIONS

We conclude that conversion of LC to OC is more prevalent among males and is probably attributable to a greater incidence of anatomical difficulties.

How does infected bile affect the postoperative course of patients undergoing laparoscopic cholecystectomy?

OBJECTIVES

To assess the rate of infected bile in patients undergoing laparoscopic cholecystectomy (LC) and to study the influence on the postoperative infective complications in this group of patients.

METHODS

Bile samples of 247 patients undergoing LC were collected and cultured for aerobic and anaerobic bacteria. All patients were given prophylactic antibiotics.

RESULTS

The overall rate of infected bile was 12.8% (56 positive cultures); of these, 54 were aerobic and 2 anaerobic bacteria. Only 2 patients developed infection at the umbilical site, and in both, the bile was sterile. None of the patients with positive bile cultures developed any signs of infection during a mean follow-up period of 26 months.

CONCLUSION

The overall rate of septic complications following LC is extremely low, and at least in our study no correlation was found between infected bile and septic complications.

Characterization of metabolites of clozapine N-oxide in the rat by micro-column high performance liquid chromatography/mass spectrometry with electrospray interface

The metabolism of clozapine N-oxide was investigated in the rat (n = 6) after a single oral dose of 20 mg kg-1. The organic extracts of rat urine were separated by conventional high performance liquid chromatography (HPLC) and individual collected fractions were analyzed by micro-column electrospray HPLC/mass spectroscopy. The compounds identified in rat urine were clozapine N-oxide, clozapine, N-desmethylclozapine, 8-deschloro-8-hydroxyclozapine, 8-deschloro-8-thiomethylclozapine, N-desmethylclozapine, 8-deschloro-8-hydroxyclozapine, 8-deschloro-8-thiomethylclozapine, N-desmethyl-8-deschloro-8-thiomethylclozapine and 8-deschloro-8-methylsulfinylclozapine. With the exception of the unchanged clozapine N-oxide, no other metabolite containing a N-oxide functional group could be found, the concentrations of clozapine N-oxide, clozapine and N-desmethylclozapine excreted from rat urine were determined utilizing a conventional HPLC procedure with UV detection. The recoveries of these three analytes reported as the percentage of the dosage from the 0.24 h urine are 0.93 +/- 0.54%, 0.06 +/- 0.03% and 0.01 +/- 0.006% respectively.

Is gamma-actin a regulator of amino acid transport?

A mutated yeast cell line incapable of growth in minimal medium with proline as the sole nitrogen source was restored to normal growth by transfection with a cDNA from mouse Ehrlich cells. The cloned cDNA (E51) was found to be 90% homologous to gamma-actin. Immediately after transfection with E51 cDNA, both alpha-aminoisobutyric acid (AIB) and proline uptake in the mutated yeast were increased, particularly at pH 5. The expression of the same E51 cDNA also enhanced amino acid uptake in Xenopus laevis oocytes after injection into the Xenopus nuclei. A mutated mammalian lymphocyte cell line (GF-17), deficient in system A transport, also showed increased Na(+)-dependent transport after transfection with E51 cDNA. Whereas the mock transfected GF-17 cells failed to grow in the selection medium, the transfectants with E51 cDNA grew better than the untransfected cells. The data are consistent with the conclusion that expression of E51 cDNA can modify inactive, endogenous amino acid transporters, permitting substantial amino acid uptake in cells deficient in amino acid transporter(s) and permitting rapid cell growth. The data suggest that the gamma-actin-like protein coded for by E51 cDNA may play a significant regulatory role in amino acid transport.

Identification of lactams as in vitro metabolites of piperidine-type phenothiazine antipsychotic drugs

The metabolism of the piperidine-type phenothiazine antipsychotic agents thioridazine, mesoridazine and sulforidazine was studied in vitro with 10,000 g liver supernatants obtained from rats and dogs. After incubations at 37 degrees C for different time intervals, the incubates were extracted with dichloromethane and the isolated compounds analyzed by HPLC, direct probe MS and on-line HPLC-MS. Five lactam metabolites of these three drugs were unequivocally identified in the rat in vitro system, but none was found in dog preparations; at least one lactam metabolite was identified for each drug in the rat. The lactams of thioridazine and thioridazine ring sulfoxide were characterized as metabolites of thioridazine for the first time in any system. The other three lactam metabolites, namely the lactams of mesoridazine, sulforidazine and mesoridazine ring sulfoxide, were found in vitro for the first time, although they have been previously reported as in vivo metabolites of these drugs. The results indicate that rat would be a more suitable animal model than dog for further studies on the formation of lactam metabolites of these drugs.

Effects of recombinant drug-specific single chain antibody Fv fragment on [3H]-desipramine distribution in rats

Tricyclic antidepressant overdose can be reversed in rats by drug-specific antibody Fab fragments, but the required Fab dose may itself by toxic. We studied the potential use of a smaller, recombinant desipramine (DMI)-specific single chain Fv fragment (B9-sFv) for this purpose. Anesthetized rats received a tracer (subtoxic) dose of [3H]-DMI followed in 15 min by B9-IgG, B9-Fab, B9-sFv (0.1 mumol of binding sites) or BSA. Each of the active treatments produced a rapid and substantial increase in the serum radiolabel concentration, whereas BSA did not (P < 0.001). The increase in serum radiolabel concentration 1 min after treatment was 13.3-fold with B9-IgG, 10.0-fold with B9-Fab and 7.3-fold with B9-sFv. Serum antibody concentrations were also highest after B9-IgG and lower with B9-Fab or B9-sFv. The 24-hr urinary excretion of radiolabel did not differ among groups, but was extensive even in the BSA group and probably represented the excretion of DMI metabolites. B9-sFv concentrations in urine or buffer at 37 degrees declined by >90% over 24 hr, but this fragment was much more stable in serum, retaining 70% of its activity after 96 hr. These data demonstrate that B9-sFv can alter markedly the distribution of [3H]-DMI in vivo. The rapidity of this effect, and its magnitude in comparison with Fab fragment or IgG, suggest that further study of B9-sFv as a treatment of DMI overdose is warranted.

Urinary metabolic profile in rat of 1-(2-methoxyphenyl)-2-methyl-2-(3-pyridyl)-1-propanone: a potential radioligand for functional diagnosis of adrenal pathology

1. The metabolism of 1-(2-methoxyphenyl)-2-methyl-2-(3-pyridyl)-1-propanone (2-MPMP) was studied in the male Sprague-Dawley rat after 50 mg/kg, i.v. dose. 2. Organic solvent extracts of urine samples were directly analysed by reversed-phase gradient hplc. The identified metabolites were also isolated by preparative tlc, and analyzed by direct probe mass spectrometry. In the case of conjugated metabolites, the urine samples were deconjugated by enzyme hydrolysis prior to extraction. The structures of metabolites were confirmed by comparison of their chromatographic behaviours, UV spectra, and mass spectra with those of authentic standards. 3. The metabolites identified in the 0-24-h urine samples were 2-hydroxyphenyl-metyrapone (2-OHPMP) and 2-hydroyphenylmetyrapone N-oxide (2-OHPMP-NO), which were present predominantly as their glucuronide and/or sulphate conjugates. 4. 2-MPMP and four of its metabolites present in the 0-24-h urine samples were quantified by a reversed-phase hplc method. The mean total urinary excretion was 75.4% of the administered dose. The major metabolites present in the urine were conjugates of 2-OHPMP-NO (54.4%) and of 2-OHPMP (18.6%). The excretion of the unchanged drug, unconjugated 2-OHPMP and 2-OHPMP-NO accounted for 1.1, 1.1 and 0.2% of the dose respectively.

Puqiedinone, a novel 5 alpha-cevanine alkaloid from the bulbs of Fritillaria puqiensis, an antitussive traditional Chinese medicine

A novel 5 alpha-cevanine alkaloid, puqiedinone [1], was isolated from the bulbs of Fritillaria puqiensis, a traditional Chinese medicine used widely for its antitussive and expectorant properties. The structure of 1 was assigned as (20R,22S,25R)-20-deoxy-5 alpha-cevanine-3 beta-ol-6-one based on spectral analysis and comparison with the structures of related known compounds. Puqietinone [2] was also identified from the same herbal plant and the structure was revised as (22R,25S)-N-methyl-22,26-epiminocholest-3 beta-ol-6-one based on spectroscopic and X-ray crystallographic methods.