Search

Background: Untargeted metabolomics approaches based on mass spectrometry obtain comprehensive profiles of complex biological samples. However, on average only 10% of the molecules can be annotated. This low annotation rate hampers biochemical interpretation and effective comparison of metabolomics studies. Furthermore, de novo structural characterization of mass spectral data remains a complicated and time-intensive process. Recently, the field of computational metabolomics has gained traction and novel methods have started to enable large-scale and reliable metabolite annotation. Molecular networking and machine learning-based in-silico annotation tools have been shown to greatly assist metabolite characterization in diverse fields such as clinical metabolomics and natural product discovery., Aim of Review: We highlight recent advances in computational metabolite annotation workflows with a special focus on their evaluation and comparison with other tools. Whilst the progress is substantial and promising, we also argue that inconsistencies in benchmarking different tools hamper users from selecting the most appropriate and promising method for their research. We summarize benchmarking strategies of the different tools and outline several recommendations for benchmarking and comparing novel tools., Key Scientific Concepts of Review: This review focuses on recent advances in mass spectral library-based and machine learning-supported metabolite annotation workflows. We discuss large-scale library matching and analogue search, the current bloom of mass spectral similarity scores, and how molecular networking has changed the field. In addition, the potentials and challenges of machine learning-supported metabolite annotation workflows are highlighted. Overall, recent developments in computational metabolomics have started to fundamentally change metabolomics workflows, and we expect that as a community we will be able to overcome current method performance ambiguities and annotation bottlenecks., (© 2022. The Author(s).)

Objectives: To assess survival of patients with muscle-invasive bladder cancer (MIBC) who underwent radical cystectomy (RC) with or without neo-adjuvant chemotherapy (NAC) according to the pathological response at RC., Methods: 965 patients with MIBC (cT2-4aN0M0) who underwent RC with or without NAC were analyzed. Among the collected data were comorbidity, clinical and pathological tumor stage, tumor grade, nodal status (y)pN, and OS. Case-control matching of 412 patients was performed to compare oncological outcomes. Kaplan-Meier curves were created to estimate OS for patients who underwent RC with or without NAC, and for those with complete response (pCR), partial response (pPR), or residual or progressive disease (PD)., Results: Patients with a pCR or pPR at RC, with or without NAC, had better OS than patients who had PD (both p values < 0.001). Moreover, the incidence of pCR was significantly higher in patients receiving NAC prior to RC than in patients undergoing RC only (31% versus 15%, respectively; p < 0.001). Case-control matching displayed better OS of patients who underwent RC with NAC, median survival not reached, than of those who underwent RC only, median 4.5 years (p = 0.023)., Conclusions: This study showed that patients with MIBC who underwent NAC with RC had a significant better OS than those who underwent RC only. The proportion of patients with a pCR was higher in those who received NAC and RC than in those who were treated by RC only. The favorable OS rate in the NAC and RC cohort was probably attributed to the higher observed pCR rate., (© 2022. The Author(s).)

A large number of quantitative trait loci (QTL) for resistance to late blight of potato have been reported with a "conventional" method in which each phenotypic trait reflects the cumulative genetic effects for the duration of the disease process. However, as genes controlling response to disease may have unique contributions with specific temporal features, it is important to consider the phenotype as dynamic. Here, using the net genetic effects evidenced at consecutive time points during disease development, we report the first conditional mapping of QTL underlying late blight resistance in potato under five environments in Peru. Six conditional QTL were mapped, one each on chromosome 2, 7 and 12 and three on chromosome 9. These QTL represent distinct contributions to the phenotypic variation at different stages of disease development. By comparison, when conventional mapping was conducted, only one QTL was detected on chromosome 9. This QTL was the same as one of the conditional QTL. The results imply that conditional QTL reflect genes that function at particular stages during the host-pathogen interaction. The dynamics revealed by conditional QTL mapping could contribute to the understanding of the molecular mechanism of late blight resistance and these QTL could be used to target genes for marker development or manipulation to improve resistance.

Background: The European Association of Endoscopic Surgery (EAES) initiated a consensus development conference on the laparoscopic resection of colon cancer during the annual congress in Lisbon, Portugal, in June 2002., Methods: A systematic review of the current literature was combined with the opinions, of experts in the field of colon cancer surgery to formulate evidence-based statements and recommendations on the laparoscopic resection of colon cancer., Results: Advanced age, obesity, and previous abdominal operations are not considered absolute contraindications for laparoscopic colon cancer surgery. The most common cause for conversion is the presence of bulky or invasive tumors. Laparoscopic operation takes longer to perform than the open counterpart, but the outcome is similar in terms of specimen size and pathological examination. Immediate postoperative morbidity and mortality are comparable for laparoscopic and open colonic cancer surgery. The laparoscopically operated patients had less postoperative pain, better-preserved pulmonary function, earlier restoration of gastrointestinal function, and an earlier discharge from the hospital. The postoperative stress response is lower after laparoscopic colectomy. The incidence of port site metastases is <1%. Survival after laparoscopic resection of colon cancer appears to be at least equal to survival after open resection. The costs of laparoscopic surgery for colon cancer are higher than those for open surgery., Conclusion: Laparoscopic resection of colon cancer is a safe and feasible procedure that improves short-term outcome. Results regarding the long-term survival of patients enrolled in large multicenter trials will determine its role in general surgery.

Background: Laparoscopic surgery is associated with reduced surgical trauma, and therefore with a less acute phase response, as compared with open surgery. Impairment of the immune system may enhance surgical infections, port-site metastases, and sepsis. The objectives of this review was to assess immunologic consequences of benign laparoscopic surgery and to highlight controversial aspects., Methods: A literature search on stress response to nonmalignant laparoscopic and open surgery was conducted using the MEDLINE and Cochrane databases. Cross-references from the reference list of major articles on the subject were used, as well as manuscripts published between 1993 and 2002., Results: Local (i.e., peritoneal) immune function is affected by carbon dioxide pneumoperitoneum. The production of tumor necrosis factor and the phagocytotic capacity of peritoneal macrophages are less lowered. The systemic stress response, as determined by delayed-type hypersensitivity response and leukocyte antigen expression on lymphocytes, shows a preservation of immune function after laparoscopic surgery, as compared with conventional surgery., Conclusions: Intraperitoneal carbon dioxide insufflation attenuates peritoneal immunity, but laparoscopic surgery is associated with a lower systemic stress response than open surgery.

Background: This study was performed to evaluate the (long-term) morbidity associated with hand-assisted laparoscopic surgery (HALS) for various indications., Methods: HALS procedures for various indications were evaluated prospectively from 1995 to 2002. The primary outcome parameters were postsurgical complications and the development of incisional hernias., Results: Twenty-six splenectomies, 51 hand-assisted laparoscopic donor nephrectomies (HLDN), 34 segmental bowel resections, 29 proctocolectomies, and 10 emergency colectomies were evaluated. A Küstner or Pfannenstiel incision was used for handport placement. Minor complications (i.e., wound complications, urinary tract infection) occurred in 15%, 12%, 26%, 7%, and 33% of the patients after, respectively, splenectomy, HLDN, bowel resection, proctocolectomy, and emergency colectomy. Major complications (i.e., hemorrhage, anastomotic leakage) occurred in 15% and 12% of the patients after, respectively, bowel resection and proctocolectomy. Incisional hernias occurred in six patients (4%), all after a wound complication in the Küstner incision., Conclusion: HALS is fast, safe, and feasible for various indications, especially HLDN and (procto-)colectomies. Little advantage can be expected when HALS is applied in splenectomy and segmental bowel (sigmoid) resection.

Background: The aim of this study is to create new ergonomic guidelines for the design of laparoscopic needle holders., Methods: An ergonomic literature study, observations in the operating room, handle-shaft angle measurements, and anthropometric data were used to compile new ergonomic criteria, specified to the function of a laparoscopic needle holder. Based on these guidelines a new needle holder was designed. The prototype and three currently available needle holders were evaluated according to the new guidelines. In addition, a pelvi-trainer test was done to measure the extreme wrist excursions., Results: The ergonomic evaluation of three commonly used handles and the new prototype indicate that the new handle is an ergonomic improvement in the field of laparoscopic needle holders: only the new handle satisfies all criteria. This is validated by the results of the pelvi-trainer test, which showed that the new prototype significantly (p <0.001) reduced the extreme wrist excursions., Conclusion: The new design guidelines for a laparoscopic needle holder result in an ergonomic improvement of the instrument.

Background: Compared to open surgery, minimally invasive surgery (MIS) relies heavily on advanced technology, such as endoscopic viewing systems and innovative instruments. The aim of the study was to objectively compare three technologically advanced laparoscopic viewing systems with the standard viewing system currently used in most Dutch hospitals., Methods: We evaluated the following advanced laparoscopic viewing systems: a Thin Film Transistor (TFT) display, a stereo endoscope, and an image projection display. The standard viewing system was comprised of a monocular endoscope and a high-resolution monitor. Task completion time served as the measure of performance. Eight surgeons with laparoscopic experience participated in the experiment., Results: The average task time was significantly greater (p <0.05) with the stereo viewing system than with the standard viewing system. The average task times with the TFT display and the image projection display did not differ significantly from the standard viewing system., Conclusion: Although the stereo viewing system promises improved depth perception and the TFT and image projection displays are supposed to improve hand-eye coordination, none of these systems provided better task performance than the standard viewing system in this pelvi-trainer experiment.

Background: This study was performed to assess the optimal display location of a flat-screen monitor for laparoscopy. It was also performed to assess the posture (objective), opinion, and preference (subjective) of subjects using a flat-screen monitor positioned in the optimal display location and a cathode-ray tube monitor on a tower next to the operating table (current situation)., Methods: Twelve surgeons performed cholecystectomies using the two display systems alternately. The postures of the operator and the assistant were assessed by an infrared video analysis system., Results: The posture of the assistant is significantly better when using a flat-screen monitor [more neutral head flexions (p = 0.036) and neutral neck torsions (p = 0.012)]. No significant differences were found for the posture of the operator. The operators and assistants felt more comfortable when using a flat-screen monitor (p = 0.008) and they preferred this display to the use of a monitor on a tower., Conclusions: The use of flat-screen monitors is better for the physical and psychological comfort of the users, even though the technical performance is inferior in comparison with that of regular monitors.

Background: Recent studies have shown that the shape of most instrument handles causes user discomfort and that none of the handles currently available on the market satisfies all ergonomic criteria. Therefore, we designed a handle with improved usability; i.e., it is easier to manipulate and its use entails less risk of injury for the operator. The aim of this study was to demonstrate that the intended improvements of the new design were successful., Methods: Six handles representative of the types that are currently available were compared with the new version. Eight surgeons used the seven handles during a precision task and a rough task in a pelvi-trainer. A questionnaire and video analyses were used to assess the usability of the handles., Results: Based on the responses to the questionnaire, we determined that there were significant differences between the new handle and the Aesculap handle (means of rotation and angle between handle and shaft). No significant differences were found between the new handle and the five other handles. The video analyses (documenting extreme vs neutral wrist excursions) showed significant differences between the new handle and the six other handles., Conclusion: Compared to the six existing handles, the new handle has significantly improved usability; in particular, its hinged design obviates the need to make extreme wrist excursions.

Organic anion transporting polypeptides (rodents: Oatps; human: OATPs) are involved in the absorption and elimination of a wide variety of structurally unrelated amphipathic organic compounds. Several members of this protein family mediate the uptake of substrates across the basolateral membrane of hepatocytes as the first step in hepatic elimination. In contrast to the well-characterized Oatp1 and Oatp2, the localization and substrate specificity of the recently cloned Oatp4 have not been investigated in detail. Therefore, we raised an antibody against the C-terminal end of Oatp4 and localized this 85-kDa protein to the basolateral membrane of rat hepatocytes. Similar to Oatp1 and Oatp2, Oatp4 is a multispecific transporter with high affinities for bromosulfophthalein, dehydroepiandrosterone sulfate, leukotriene C4, and anionic peptides. In addition, we compared the substrate specificity of Oatp4 to that of Oatp3, which so far has mainly been shown to mediate intestinal bile acid transport. Oatp3 had a similar broad substrate specificity, but in general much lower affinities than Oatp4. Thus, while Oatp4 seems to work in concert with Oatp1 and Oatp2 in the basolateral membrane of rat hepatocytes, Oatp3 is a multispecific transport system in the small intestine.

Alkaline cellulase-producing actinomycete strains were isolated from mud samples collected from East African soda lakes. The strains were identified as novel Streptomyces spp. by 16S rDNA sequence analysis. A cellulase gene (cel12A) from Streptomyces sp. strain 11AG8 was cloned by expression screening of a genomic DNA library in Escherichia coli. From the nucleotide sequence of a 1.5-kb DNA fragment, an open reading frame of 1,113 nucleotides was identified encoding a protein of 371 amino acids. From computer analysis of the sequence, it was deduced that the Cel12A mature enzyme is a protein of 340 amino acids. The protein contained a catalytic domain, a glycine-rich linker region, and a cellulose-binding domain of 221, 12, and 107 amino acids, respectively. FASTA analysis of the catalytic domain of Cel12A classified the enzyme as a family 12 endoglucanase and the cellulose-binding domain as a family IIa CBD. Streptomyces rochei EglS was determined as nearest neighbor with a similarity of 75.2% and 61.0% to the catalytic domain and the cellulose-binding domain, respectively. The cell2A gene was subcloned in a Bacillus high-expression vector carrying the Bacillus amyloliquefaciens amylase regulatory sequences, and the construct was transformed to a Bacillus subtilis host strain. Crude enzyme preparations were obtained by ultrafiltration of cultures of the Bacillus subtilis recombinant strain containing the 11AG8 cell2A gene. The enzyme showed carboxymethylcellulase (CMCase) activities over a broad pH range (5-10) with an optimum activity at pH 8 and 50 degrees C. The enzyme retained more than 95% of its activity after incubation for 30 min under these conditions.

Background: Advanced laparoscopic surgery is complex and time-consuming. Achieving consistent efficacy and safety throughout the entire procedure is always a problem. For this reason, hand-assisted laparoscopic surgery (HALS) was developed., Methods: Devices were designed to allow manual access to the abdomen through the utility laparotomy. By using one hand in the abdomen during laparoscopy, the surgeon regains direct tactile sensation and acquires improved hand-eye coordination. The safety of the individual devices has been tested in RCT for the registration of the individual devices. An index known as Surgical Action Efficiency was calculated for in six patients undergoing laparoscopic colon resection and six patients with hand-assisted colon resections., Results: All of the registered devices are safe. Surgical Action Efficiency for the laparoscopy group was 55 +/- 14%; for the HALS group, it was 71 +/- 4%. This result is statistically significant (p < 0.05)., Conclusion: HALS is a safe and efficient method by which it is possible to combine the established convenience and safety of open surgery with the advantages of minimally invasive surgery.

A number of novel alkaliphilic organotrophic bacteria have been isolated from several saline and alkaline East African soda lakes. The new isolates grow at pH values between 7.0 and 11.0, with pH optima for growth between 9.0 and 10.0. Growth occurs at total salts concentration between 0% and 20% (w/v) with optimum at 0%-7% (w/v). Phylogenetic analyses based on 16S rDNA sequence comparison indicate that these isolates are related (>96% similarity) to members of the Halomonadaceae within the gamma-3 subdivision of the Proteobacteria. These analyses indicate that existing species within the Halomonadaceae fell within three main groups, one group comprising the type species of Halomonas, Halomonas elongata, and a number of other known species including one soda lake isolate. A second group constituting most of the remaining known species of Halomonas and related Chromohalobacter spp. includes 3 soda lake isolates with high DNA-DNA homologies. The third group included Halomonas halodenitrificans, Halomonas desiderata, Halomonas cupida, and 13 soda lake isolates. Phenotypic comparisons indicated that the majority of soda lake strains shared similar morphological, phenotypic, and chemotaxonomic properties to known strains of Halomonas but grew under alkaline conditions. The 3 soda lake isolates with high DNA-DNA homologies were, however, significantly different in antibiotic sensitivity pattern and in the utilization of several substrates, were unable to reduce nitrite, and showed low DNA-DNA homologies with known halomonads in the same group. We propose that these isolates comprise a new species of the genus Halomonas that we name Halomonas magadii sp. nov. The type strain is strain 21 MI (NCIMB 13595).

Background: Sensory feedback is reduced considerably in minimally invasive procedures by the interposition of instruments, causing loss of direct manual contact with the tissue. The purpose of this study was to evaluate the feedback quality of commercially available reusable and disposable laparoscopic dissectors., Methods: A total of 31 participants were asked to feel a simulated arterial pulse with their bare fingers and through laparoscopic dissectors, tweezers, an orthopedic forceps, and a laparoscopic low-friction prototype. The absolute sensory threshold was determined by the psychophysical method of limits., Results: The sensory feedback quality was significantly better for the reusable dissectors tested than for the disposable dissector (p < 0.001). Nevertheless, the reusable dissectors were at least eight times less sensitive than bare fingers. Furthermore, sensitivity qualities were highly variable, depending on the dissector tested., Conclusions: This study showed that the overall sensitivity loss through instruments could be accurately assessed, proving that the sensory feedback for commercially available instruments was low compared to bare fingers. The good sensory feedback results of the prototype indicated that careful design could decrease the overall sensitivity loss.

With the development of endoscopic surgery, new hazards of high-frequency (HF) electrosurgery have been recognized. The potential risks of monopolar electrosurgery, the limitations of bipolar technique, and the need to reduce instrument interchange have favored the use of ultrasonic technology, which becomes more and more popular. This work aims at presenting the main features of the currently available ultrasonically activated scalpels, as well as their advantages, limitations, and indications.

Two novel alkaliphilic aerobic organotrophic bacteria have been isolated from a moderately saline and alkaline East African soda lake. The new isolates grow at pH values between 6 and 10, with a pH optimum for growth of 9.0, and at a salt concentration between 0% and 10% (w/v). Phylogenetic analysis based on 16S rDNA sequence shows that these isolates are very closely related (99.6% similarity) and are members of the monospecific genus Dietzia (98.8% and 98.7% similarity). DNA/DNA hybridization revealed a relatedness of 83% between the two isolates, but only 8% between them and the type strain Dietzia maris. The G + C content as measured by thermal denaturation is 66.1 mol%. Phenotypic comparisons between D. maris and one isolate showed that they share very similar morphological and chemotaxonomic properties, but differ significantly in carbon source utilization profiles and halotolerance in alkaline medium. We propose a second species of this genus which we name Dietzia natronolimnaios (type strain 15LN1 = CBS 107.95).

Background: Total extraperitoneal laparoscopic surgery is an alternative to the laparoscopic transperitoneal route; however, its effects on hemodynamics have not been adequately studied. This experimental study compared the effects of intraperitoneal insufflation and extraperitoneal insufflation on hemodynamics and oxygen transport., Methods: Sixteen pigs were randomly assigned for intraperitoneal insufflation or extraperitoneal insufflation with 15 mmHg carbon dioxide. Hemodynamic and oxygen transport parameters were taken during an hour of insufflation and analyzed for statistical differences., Results: During extraperitoneal CO2 pneumoperitoneum central venous filling pressures (central venous pressure, pulmonary capillary wedge pressure and mean pulmonary arterial pressure) and end-tidal CO2 increased slower but to a similar magnitude in comparison to intraperitoneal insufflation. Cardiac output and indices of oxygen consumption and oxygen delivery were equally affected by both types of insufflation. Arterial CO2 pressure increased significantly more during intraperitoneal insufflation., Conclusion: The data from this study suggest that extraperitoneal insufflation might result in less cardiovascular impairment than intraperitoneal insufflation.

Background: Disadvantages related to CO2 pneumoperitoneum have led to development of the abdominal wall retractor (AWR), a device designed to facilitate laparoscopic surgery without conventional pneumoperitoneum (15 mmHg CO2). We investigated the effects of the AWR on hemodynamics and gas exchange in humans. We also investigated whether the use of an AWR imposed extra technical difficulties for the surgeon. A pilot study revealed that cholecystectomy without low-pressure pneumoperitoneum was technically impossible., Methods: A prospective randomized controlled trial: Twenty patients undergoing laparoscopic cholecystectomy were randomly allocated into group 1: AWR with low-pressure pneumoperitoneum (5 mmHg), or group 2: conventional pneumoperitoneum (15 mmHg)., Results: Surgery using the AWR lasted longer, 72 +/- 16 min (mean +/- SD) vs 50 +/- 18 min compared with standard laparoscopic cholecystectomy. There were no differences between the groups with respect to hemodynamic parameters, although a small reduction of the cardiac output was observed using conventional pneumoperitoneum (from 3.9 +/- 0.7 to 3. 2 +/- 1.1 l/min) and an increase during AWR (from 4.2 +/- 0.9 to 5.2 +/- 1.5 l/min). Peak inspiratory pressures were significantly higher during conventional pneumoperitoneum compared to AWR. A slight decrease in pH accompanied by an increase in CO2 developed during pneumoperitoneum and during the use of the AWR. In both groups arterial PO2 decreased., Conclusions: The results indicate that the view was impaired during use of the AWR and therefore its use was difficult and time-consuming. Possible advantages of this devices' effects on hemodynamics and ventilatory parameters could not be confirmed in this study.

During laparoscopy elevations in arterial pressure and a decrease in cardiac output have been reported. Laparoscopic surgery performed in the prone position may be advantageous for some surgical procedures, but the hemodynamic effects of pneumoperitoneum in this position have not been studied. We studied the effects of different levels of increased intraabdominal pressure on hemodynamics and oxygen transport in eight pigs in the prone and the supine position. Increases in intraabdominal pressure did not result in decreased cardiac output or in a reduction of oxygen transport and consumption in either position. These results suggest that laparoscopy in the prone position does not result in more severe hemodynamic depression than laparoscopy in the supine position.

Obtaining a clear view during laparoscopic surgery in the posterior abdominal cavity, on the abdominal backwall, or during colon surgery is time consuming and therefore one of the major objections to these procedures. In an experimental setting we positioned the animals in the prone position using the abdominal flanks to introduce the trocars. Our experience with this position is that a clear and unobstructed view of the abdominal back wall and the large intestines is obtained, facilitating laparoscopic procedures in these areas.

Rapid implementation of left ventricular assistance without thoracotomy for temporary support of patients with severe, life-threatening, acute cardiac power failure potentially expands applications of such support devices. A thoracoscopic technique for direct cannulation of the left atrium is described. In healthy closed-chest pigs, it proved a feasible method for effective volume unloading of the left ventricle.

Unlabelled: The absorption kinetics of different pharmaceutical formulations of orally and rectally administered flecainide have been assessed in a cross-over study in 7 healthy volunteers. The subjects received single doses of flecainide after a washout period of at least one week. A tablet, an oral solution, a rectal solution and a 10 min i.v. infusion during 10 min each containing 100 mg flecainide were administered to the subjects in a randomized order. The mean absolute bioavailability was 98%, 78% and 81% for the rectal and oral solutions and the tablet. The lag time after administration of the oral solution was 0.33 h and it was 0.86 h after the tablet and 0.18 h after the rectal solution. The mean time to the peak serum concentration (tmax) after the rectal solution (0.67 h) was shorter than after either the tablet (4 h) or oral solution (1 h). The maximum serum concentration (Cmax) was 0.29 mg.l-1 after the rectal solution, 0.14 mg.l-1 after the tablet and 0.17 mg.l-1 after the oral solution. All the volunteers showed significantly higher serum flecainide concentrations during the first 20 min of the absorption phase after rectal administration of 100 mg flecainide as a solution compared to its oral administration., In Conclusion: based on the absolute bioavailability, Cmax, tmax, and lag times, rectal administration of flecainide solution gave a better absorption profile than after oral tablet or solution.

Rectal absorption of morphine HCl from aqueous vehicles at different pHs in man has been compared with an orally administered solution. Plasma concentrations of morphine were measured by electrochemical HPLC analysis after a single dose of 10 mg morphine HCl, in a cross-over study in 7 volunteers. Rectal absorption of morphine was dependent on pH, which could be explained as being due to pH partitioning. The absorption rate and bioavailability could be greatly improved, as compared to orally administered morphine, by adjusting the pH. It was concluded that a rectal solution adjusted to pH 7 to 8 provided an entirely adequate dosage form.

The pharmacokinetics of Indocyanine Green (ICG) has been studied in 15 patients given 0.5, 1.0 and 2.0 mg.kg-1. The plasma disappearance and biliary excretion rate were measured in patients with tightly fitting catheters under slight negative pressure in order to achieve complete collection of bile. Recovery of unchanged ICG in bile over 18 h after the i.v. injection was 80% of the dose in all three dose groups. Plasma disappearance in all 3 groups was biphasic, showing an initial phase with a t1/2 of 3-4 min and a secondary phase with a dose-dependent apparent t1/2 of 67.6, 72.5 and 88.7 min, respectively. After 0.5 and 1.0 mg.kg-1 the biliary excretion rate curves showed an ascending phase with a mean t1/2 of 5 min and a descending phase with a mean t1/2 of 72 min. It was inferred that the secondary component of the plasma-decay mainly reflected the biliary excretion rate. After 2.0 mg.kg-1 in some patients the biliary excretion curve showed features of saturation; the t1/2 of the descending phase ranged from 73 to 440 min, and the time of maximal excretion was increased from 1.3 to 2.7 h after injection, whilst the mean maximal excretion rate was in the same range as the excretion rate after the 1.0 mg.kg-1 dose. The non-linear pharmacokinetics was only moderately reflected in the measured plasma disappearance patterns. Two compartment analysis of the plasma levels indicated a clearance of 230-260 ml.min-1, whereas the clearance conventionally calculated from the initial t1/2 was 475 ml.min-1.(ABSTRACT TRUNCATED AT 250 WORDS)

In bile specimens from postoperative patients with biliary drainage following cholecystectomy, in addition to unchanged dibromosulfophthalein (DBSP), a single polar metabolite of DBSP was found after i.v. injection of 5 mg/kg of the diagnostic dye. This metabolite, which has not previously been detected, was resistant to beta-glucuronidase and arylsulfatase and was remarkably stable in strongly acid and alkaline solutions. It exhibited the same spectrum and colour change interval as unchanged DBSP. Further studies of its identity revealed that it gave a ninhydrin-positive reaction and that its Rf-value on TLC could be restored by Raney-nickel reduction. Amino-acid analysis after reduction and acid hydrolysis showed an increase in glutamic acid and alanine that can be considered as splitting products of conjugated glutathione following these procedures. Estimation of the quantity of this possible glutathione conjugate indicates that it is formed less rapidly than the glutathione derivative of the tetrabromoanalogue BSP, and that it represents up to 25% of the total dye excreted in bile. The observed metabolism of DBSP in man may complicate its use in the study of hepatic transport function, and negates the previous assumption that, as in certain other animal species, the dye is excreted unchanged.

The oral absorption of bezitramide 5 mg was studied in 7 human volunteers, using a specific radioimmuno-assay which measured both bezitramide and its active metabolite R-4618. A lag time of 0.5-1.0 h and a Cmax of 5.4 ng/ml plasma were found, the latter occurring 2.5-3.5 h after administration. The apparent elimination half-life varied from 11 to 24 h. Less than 0.3% of the dose was excreted unchanged in the urine. High concentrations in the faeces of some individuals indicate incomplete absorption and/or biliary secretion. The analgesic effect, using a standardized superficial electrical stimulation method, reached its maximum between 2.5 and 3.5 h after dosing, in accordance with the absorption phase. The duration of the effect was highly variable. Experiments in rats (n = 6, 3H-bezitramide 2.5 micrograms), demonstrated extensive biliary excretion (up to 70% of total radioactivity) and less than 3% of the label was removed by urinary excretion.