[Trial provision in clinical routine. Definition of terms and investigation of normal practice]. / Probestellungen im Klinikalltag. Begriffsdefinition und Untersuchung der gängigen Praxis.

BACKGROUND: It has become common for hospitals to borrow medical devices from manufacturers to test and try them during the daily routine before purchasing which today is known as trial provision. This study aims at offering a precise definition of trial provisions and a description of the way of proceeding. METHODS: A total of 60 medical practitioners in 5 German hospitals were surveyed (surgeons n = 40, 66.7 %, radiologists n = 12, 20 % and anesthesiologists n = 8, 13.3 %). Manufacturers and distributors of medical devices (n = 10) and hospital administration executives (n = 8) were also interviewed. RESULTS: Trial provisions are a promotional marketing tool for manufacturers of medical devices. By lending the device over a specific period for testing before purchasing, hospitals can gain experience in the usage and handling of devices on which a purchase decision can be made. The survey revealed that there are basically three procedural methods which can, however, differ even within one hospital. CONCLUSION: Trial provisions influence purchasing decisions in clinics. If implemented incorrectly trial provisions may compromise physical integrity, safety and health of patients and can thus lead to judicial and legal consequences for hospitals and medical staff.

Ergonomics of disposable handles for minimally invasive surgery.

BACKGROUND: The ergonomic deficiencies of currently available minimally invasive surgery (MIS) instrument handles have been addressed in many studies. In this study, a new ergonomic pistol handle concept, realized as a prototype, and two disposable ring handles were investigated according to ergonomic properties set by new European standards. METHODS: In this study, 25 volunteers performed four practical tasks to evaluate the ergonomics of the handles used in standard operating procedures (e.g., measuring a suture and cutting to length, precise maneuvering and targeting, and dissection of a gallbladder). Moreover, 20 participants underwent electromyography (EMG) tests to measure the muscle strain they experienced while carrying out the basic functions (grasp, rotate, and maneuver) in the x, y, and z axes. The data measured included the number of errors, the time required for task completion, perception of pressure areas, and EMG data. The values for usability in the test were effectiveness, efficiency, and user satisfaction. Surveys relating to the subjective rating were completed after each task for each of the three handles tested. RESULTS: Each handle except the new prototype caused pressure areas and pain. Extreme differences in muscle strain could not be observed for any of the three handles. Experienced surgeons worked more quickly with the prototype when measuring and cutting a suture (approximately 20%) and during precise maneuvering and targeting (approximately 20%). On the other hand, they completed the dissection task faster with the handle manufactured by Ethicon. Fewer errors were made with the prototype in dissection of the gallbladder. In contrast to the handles available on the market, the prototype was always rated as positive by the volunteers in the subjective surveys. CONCLUSIONS: None of the handles could fulfil all of the requirements with top scores. Each handle had its advantages and disadvantages. In contrast to the ring handles, the volunteers could fulfil most of the tasks more efficiently using the prototype handle without any remarkable pressure areas, cramps, or pain.

Ergonomic usability testing of operating room devices.

Medical errors in the operating room due to design, technological factors and poor human factors engineering are common. Determining the factors which facilitate or hinder successful performance during the use of medical systems is critical to the creation of standardized metrics for usability of medical devices in the operating room. Creation of a standardized evaluation for usability based on international standards and user-centered design principles can help determine what role these factors have in medical errors. In addition, device design can be evaluated to promote safety, measured objectively by metrics such as reduction in medical errors with a decrease in performance time.

[Working conditions in the operating room: surgeons surveyed during the annual meeting of the German society of surgery 2004]. / Ergebnisse der Umfrage zu den Arbeitsbedingungen im OP auf dem Deutschen Chirurgenkongress 2004.

For the evaluation of working place conditions in the operating room a survey was conducted among the surgeons working in German hospitals. Questions regarded the personal profile, the architectural situation, the devices and instruments as well as the working posture. The answers to the 60 questions display a high potential for improvement within all fields. Every single group working in the operating room, as well as their professional organizations are asked to work on the optimization of the working place conditions in the operating room in terms of improvement of quality and efficiency.

Ergonomic testing of two different types of handles via virtual reality simulation.

BACKGROUND: Ergonomics in laparoscopic surgery is an unsolved problem. Deficiencies of the instrument handles are well-known and described in several reports and studies. Today, virtual training modules for laparoscopic surgery are available. The aim of this study was to evaluate the ability of a virtual reality (VR) simulator to determine the ergonomic properties of two different laparoscopic instrument handles. METHODS: Two different types of handles, a ring and an axial handle from Richard Wolf, were used to perform the short clip and cut task of the Xitact 500 LS simulator. The task was repeated every 2 days for a period of 5 weeks. After every trial the volunteers were asked structured questions about their preferences while using the two handles. RESULTS: The axial handle was superior or equal to the ring handle in all criteria. Learning curves over the entire time and day by day were similar. No differences were found for travel distances and error rates, but task times were different for both handles. The subjects preferred the axial handle at the end of the study. CONCLUSION: It is possible to determine differences in ergonomics of handle design with a VR trainer. In this study, the Richard Wolf axial handle was superior to the ring handle.

Monitor position in laparoscopic surgery.

BACKGROUND: One of the key problems in laparoscopy is the ergonomic positioning of the monitor. In this study we tested task performance and muscle strain of subjects in relation to monitor position during laparoscopic surgery. METHODS: Eighteen subjects simulated laparoscopic suturing by threading tiny pearls with a curved needle. This was repeated in three monitor positions (15 min each): frontal at eye level (A), frontal in height of the operating field (B), and 45 degrees to the right side at eye level (C). Subjects were not allowed to turn their heads during these sessions. After the test they were asked for their preferred monitor position. During all tests the electromyographic (EMG) activity of the main neck muscles was recorded and the number of pearls was counted. RESULTS: The EMG activity was significantly lower for position A compared to positions C and B (p < 0.05). No significant difference was found between positions B and C. The number of threaded pearls as an indicator for task performance was highest for position B. The difference was statistically significant compared to position C (p = 0.0008) but not between positions A and C (p = 0.0508) or A and B (p = 0.0575). When asked for the preferred monitor position, nine subjects chose two monitors in the frontal positions A and B. No subject preferred the monitor at the side position (C). CONCLUSION: Regarding EMG data, the monitor positioned frontal at eye level is preferable. Reflecting personal preferences of subjects and task performance, it should be of advantage to place two monitors in front of the surgeon: one in position A for lowest neck strain and the other in position B for difficult tasks with optimal task performance. The monitor position at the side is not advisable.

Ergonomic aspects of five different types of laparoscopic instrument handles under dynamic conditions with respect to specific laparoscopic tasks: an electromyographic-based study.

BACKGROUND: The ergonomic deficiencies of various minimally invasive surgery (MIS) instrument handles are well-known. In the past, many studies have been performed to gain a better understanding of ergonomics in MIS. The current study investigates muscle strain during various dynamic tasks with different instrument handles. METHODS: Five different handle designs were tested: the axial handle (Aesculap), the vario handle (own model), multifunctional and ring handles (both Karl Storz), and the shank handle (Wilo). Ten subjects without any surgical training tested the following instrument functions: precise dynamic movement, rotation of the closed instrument, and simultaneous opening and closing of the effector. During these three trials, task performance (errors/duration) and the electromyographic activity of the hand and lower arm muscles were measured. RESULTS: Regarding the errors and the time required to carry out the tasks, the five handles showed similar results. The muscle activity was lowest for the precise dynamic movement task and highest during the rotation task. The axial handle required significantly more muscle activity than all other handles. CONCLUSION: On the basis of these data, it was possible to construct characteristic muscle activation patterns for each handle. However, these patterns were not task specific. Accordingly, they may form a basis to improve the ergonomics of MIS handles with regard to muscle strain.

Ergonomic aspects of four different types of laparoscopic instrument handles with respect to elbow angle. An electromyogram-based study.

BACKGROUND: Only few studies have tested different ergonomic aspects of the working posture assumed by laparoscopic surgeons. Although no experimental data are available for a laparoscopic setting, a working posture with a horizontal forearm or an elbow angle 90 degrees to 120 degrees has been recommended for performing minimally invasive surgery (MIS). The comparison of electromyogram (EMG) activities in different muscles provides information about the force developed by each muscle and allows assessment of its contribution to a functional movement. The current study aimed to investigate whether certain handles do not support this posture. METHODS: For this study, 12 volunteers were postured in two different standardized arm positions, defined by elbow angles of 90 degrees and 120 degrees. They were manipulating a 0.1-N and a 2.5-N microswitch with four different types of instrument handle design: axial handle, ring handle, shank handle, Hirschberg handle. During the test, the EMG activities of five forearm muscles were recorded and normalized with respect to the maximum voluntary activity of the respective muscle. RESULTS: Virtually no significant difference in EMG activity was found between the two elbow angles in any of five forearm muscles for a simple grasping maneuver. Thus, the muscle activity required to manipulate different types of MIS handles is similar for the elbow angles of 120 degrees and 90 degrees. CONCLUSIONS: The current study did not show relevant differences between the two elbow angles for any of the four handles during a simple grasping maneuver with respect to the force required in the main forearm muscles.

Scyptolin A and B, cyclic depsipeptides from axenic cultures of Scytonema hofmanni PCC 7110.

Two novel cyclic depsipeptides were isolated from axenic cultures of the terrestrial cyanobacterium Scytonema hofmanni PCC 7110 and designated scyptolin A and B. Amino acid analyses in context with mass and 1H/13C NMR spectroscopies revealed a composition typical for heterologous cyanopeptolins but containing the uncommon residue 3'-chloro-N-methyl-Tyr (cmTyr) and a unique sidechain. Scyptolin A and B both consist of the N-acylated peptide But(1)-Ala(2)-Thr(3)-Thr(4)-Leu(5)-Ahp(6) (3-amino-6-hydroxy-2-oxo-1-piperidine)-Thr(7)-cmTyr(8)-Val(9), which forms a 19-membered ring by esterification of the carboxyl of Val(9) with the hydroxyl of Thr(4). In scyptolin B, the hydroxyl of the Thr(3) residue is additionally esterified with N-butyroyl-Ala. Both scyptolin A and B exhibit selective inhibition of porcine pancreatic elastase in vitro with IC(50) values of 3.1 microg/ml.

Transformation of acridone synthase to chalcone synthase.

Acridone synthase (ACS) and chalcone synthase (CHS) catalyse the pivotal reactions in the formation of acridone alkaloids or flavonoids. While acridone alkaloids are confined almost exclusively to the Rutaceae, flavonoids occur abundantly in all seed-bearing plants. ACSs and CHSs had been cloned from Ruta graveolens and shown to be closely related polyketide synthases which use N-methylanthraniloyl-CoA and 4-coumaroyl-CoA, respectively, as the starter substrate to produce the acridone or naringenin chalcone. As proposed for the related 2-pyrone synthase from Gerbera, the differential substrate specificities of ACS and CHS might be attributed to the relative volume of the active site cavities. The primary sequences as well as the immunological cross reactivities and molecular modeling studies suggested an almost identical spatial structure for ACS and CHS. Based on the Ruta ACS2 model the residues Ser132, Ala133 and Val265 were assumed to play a critical role in substrate specificity. Exchange of a single amino acid (Val265Phe) reduced the catalytic activity by about 75% but grossly shifted the specificity towards CHS activity, and site-directed mutagenesis replacing all three residues by the corresponding amino acids present in CHS (Ser132Thr, Ala133Ser and Val265Phe) fully transformed the enzyme to a functional CHS with comparatively marginal ACS activity. The results suggested that ACS divergently has evolved from CHS by very few amino acid exchanges, and it remains to be established why this route of functional diversity has developed in the Rutaceae only.

Purification and antigenicity of flavone synthase I from irradiated parsley cells.

Flavone synthase I, a soluble 2-oxoglutarate-dependent dioxygenase catalyzing the oxidation of flavanones to flavones in several Apiaceae species, was induced in parsley cell cultures by continuous irradiation with ultraviolet/blue light for 20 h. The enzyme was extracted from these cells and purified by a revised purification protocol including the fractionation on hydroxyapatite, Fractogel EMD DEAE, and Mono Q anion exchangers, which resulted in an apparently homogeneous flavone synthase at approximately 10-fold higher yield as compared to the previous report. The homogeneous enzyme was employed to raise an antiserum in rabbit for partial immunological characterization. The specificity of the polyclonal antibodies was demonstrated by immunotitration and Western blotting of the crude ammonium sulfate-fractionated enzyme as well as of the enzyme at various stages of the purification. High titer cross-reactivity was observed toward flavone synthase I, showing two bands in the crude extract corresponding to molecular weights of 44 and 41 kDa, respectively, while only the 41 kDa was detected on further purification. The polyclonal antiserum did not cross-react with recombinantly expressed flavanone 3beta-hydroxylase from Petunia hybrida or flavonol synthase from Citrus unshiu, two related 2-oxoglutarate-dependent dioxygenases involved in the flavonoid pathway.

Cloning of parsley flavone synthase I.

A cDNA encoding flavone synthase I was amplified by RT-PCR from leaflets of Petroselinum crispum cv. Italian Giant seedlings and functionally expressed in yeast cells. The identity of the recombinant, 2-oxoglutarate-dependent enzyme was verified in assays converting (2S)-naringenin to apigenin.

Ergonomics: requirements for adjusting the height of laparoscopic operating tables.

BACKGROUND AND OBJECTIVES: In the last few years many new instruments and devices have been developed and introduced into the operating room (OR). A debate has been ongoing about the optimal ergonomic posture for the operating staff. From practical experience, we have learned that the operating tables cannot be adjusted adequately to allow surgeons of different stature to maintain a comfortable posture. The goal of this study was to establish the most ergonomic table height for the particular physique of the surgeon and the different types of laparoscopic instrument handles that he or she uses. METHODS: In a simulated model, two probands of different stature (50th [BS 50] and 95th [BS 95] percentile) used laparoscopic instruments with four different handle designs (shank, pistol, axial, and rod). The instruments were inserted into a board in three different angles ([IA] = 20 degrees, 30 degrees, 40 degrees). Additionally the elbow angles (EA) of the volunteers were fixed to either 90 degrees or 120 degrees. For every variable (size of surgeon and his or her elbow angle, design of handle, insertion angle of the instrument) the height of the board, as a parameter for the level of the abdominal wall of a patient with pneumoperitioneum, was measured from the floor. RESULTS: All parameters had an effect on the optimal operating table height. The lowest required operating table level was 30 cm, the highest was 60.5 cm. In laparoscopic surgery-long shafted instruments and patients with pneumoperitoneum-the tabletops are too high for over 95% of all surgeons. As skin incision and wound suture are performed the conventional way, the operating tabletop must be adjustable up to the common height of 122 cm. The maximal difference between the optimal heights of the OR-table for one volunteer using two different handles with different insertion angles of the instruments (BS 95, EA 90 degrees, IA 20 degrees, rod handle to BS 50, EA 120 degrees, IA 40 degrees, axial handle) was about 27 cm. CONCLUSION: New operating tables with a much lower adjustability are necessary to fulfill ergonomic requirements. The use of differently designed handles can hinder the ergonomic posture of the surgeon, because each handle requires a different working height.

Specificities of functionally expressed chalcone and acridone synthases from Ruta graveolens.

The common rue, Ruta graveolens L., expresses two types of closely related polyketide synthases that condense three malonyl-CoAs with N-methylanthraniloyl-CoA or 4-coumaroyl-CoA to produce acridone alkaloids and flavonoid pigments, respectively. Two acridone synthase cDNAs (ACS1 and ACS2) have been cloned from Ruta cell cultures, and we report now the cloning of three chalcone synthase cDNAs (CHS1 to CHS3) from immature Ruta flowers. The coding regions of these three cDNAs differ only marginally, and the translated polypeptides show about 90% identity with the CHSs from Citrus sinensis but less than 75% with the Ruta endogeneous ACSs. CHS1 was functionally expressed in Eschericha coli and its substrate specificity compared with those of the recombinant ACS1 and ACS2. 4-Coumaroyl-CoA was the preferred starter substrate for CHS1, but cinnamoyl-CoA and caffeoyl-CoA were also turned over at significant rates. However, N-methylanthraniloyl-CoA was not accepted. In contrast, highly active preparations of recombinant ACS1 or ACS2 showed low, albeit significant, CHS side activities with 4-coumaroyl-CoA, which on average reached 16% (ACS1) and 12% (ACS2) of the maximal activity determined with N-methylanthraniloyl-CoA as the starter substrate, while the conversion of cinnamoyl-CoA was negligible with both ACSs. The condensation mechanism of the acridone ring system differs from that of chalcone/flavanone formation. Nevertheless, our results suggest that very minor changes in the sequences of Ruta CHS genes are sufficient to also accommodate the formation of acridone alkaloids, which will be investigated further by site-directed mutagenesis.

[Working posture of laparoscopy-practicing surgeons: ideal and reality]. / Die Arbeitshaltung des laparoskopisch tätigen Chirurgen: Ideal und Wirklichkeit.

Since laparoscopic surgery has been established the advantages for the patients of minimal invasive surgery have been discussed extensively. But this method holds considerable disadvantages, due to the non-ergonomic surgeons working position. This is mainly caused by the false positioning of the monitor and operating table as well by the use of foot switches and differing instrument handles. The common working position of the laparoscopically working surgeon leads to serious risks for the patient. The industry and hospital administrations do not know anything about this and only few surgeons are aware of these dangers. The authors want to draw attention to the insufficiencies of the laparoscopic working place. Due to missing resources until now no general concept has been developed that meets current standards.

Purification of recombinant flavanone 3beta-hydroxylase from petunia hybrida and assignment of the primary site of proteolytic degradation.

Flavanone 3beta-hydroxylase catalyzes the Fe(II)/oxoglutarate-dependent hydroxylation of (2S)-flavanones to (2R,3R)-dihydroflavonols in the course of flavonol/anthocyanin or catechin biosynthesis. The enzyme from Petunia hybrida consists of a 41,655-Da polypeptide that is prone to rapid proteolysis in crude plant extracts as well as on expression in Escherichia coli, and commercial protease inhibitors were inefficient in stopping the degradation. To pinpoint the primary site of proteolysis and to improve the activity yields, two revised schemes of purification were developed for the recombinant polypeptides. Applying a four-step protocol based on extraction and ion-exchange chromatography at pH 7.5, the primary, catalytically inactive proteolytic enzyme fragment (1.1 mg) was isolated and shown to cross-react on Western blotting as one homogeneous band of about 38 kDa. Mass spectrometric analysis assigned a mass of 37,820 +/- 100 Da to this fragment, and partial sequencing revealed an unblocked amino terminus identical to that of the native 3beta-hydroxylase. Thus, the native enzyme had been degraded by proteolysis of a small carboxy-terminal portion, and the primary site of cleavage must be assigned most likely to the Glu 337-Leu 338 bond, accounting for a loss of about 3800 Da. Alternatively, the enzyme degradation was greatly reduced when the extraction of recombinant bacteria was carried out with phosphate buffer at pH 5.5 followed by size exlusion and anion-exchange chromatography. This rapid, two-step purification resulted in a homogeneous 3beta-hydroxylase of high specific acitivity (about 32 mkat/kg) at roughly 5% yield, and the procedure is a major breakthrough in mechanistic investigations of this class of labile dioxygenases.

The monomeric polypeptide comprises the functional flavanone 3beta-hydroxylase from Petunia hybrida.

Flavanone 3beta-hydroxylase catalyzes the Fe(II)/oxoglutarate-dependent hydroxylation of (2S)-flavanones to (2R,3R)-dihydroflavonols in the biosynthesis of flavonoids, catechins and anthocyanidins. The enzyme had been partially purified from Petunia hybrida and proposed to be active as a dimer of roughly 75 kDa in size. More recently, the Petunia 3beta-hydroxylase was cloned and shown to be encoded in a 41655 Da polypeptide. In order to characterize the molecular composition, the enzyme was expressed in a highly active state in Escherichia coli and purified to apparent homogeneity. Size exclusion chromatographies of the pure, recombinant enzyme revealed that this flavanone 3beta-hydroxylase exists in functional monomeric and oligomeric forms. Protein cross-linking experiments employing a specific homobifunctional sulfhydryl group reagent or the photochemical activation of tryptophan residues confirmed the tendency of the enzyme to aggregate to oligomeric complexes in solution. Thorough equilibrium sedimentation analyses, however, revealed a molecular mass of 39. 2+/-12 kDa for the recombinant flavanone 3beta-hydroxylase. The result implies that the monomeric polypeptide comprises the catalytically active flavanone 3beta-hydroxylase of P. hybrida, which may readily associate in vivo with other proteins.

Site-directed mutagenesis of the active site serine290 in flavanone 3beta-hydroxylase from Petunia hybrida.

Flavanone 3beta-hydroxylase (FHT) catalyzes a pivotal reaction in the formation of flavonoids, catechins, proanthocyanidins and anthocyanidins. In the presence of oxygen and ferrous ions the enzyme couples the oxidative decarboxylation of 2-oxoglutarate, releasing carbon dioxide and succinate, with the oxidation of flavanones to produce dihydroflavonols. The hydroxylase had been cloned from Petunia hybrida and expressed in Escherichia coli, and a rapid isolation method for the highly active, recombinant enzyme had been developed. Sequence alignments of the Petunia hydroxylase with various hydroxylating 2-oxoglutarate-dependent dioxygenases revealed few conserved amino acids, including a strictly conserved serine residue (Ser290). This serine was mutated to threonine, alanine or valine, which represent amino acids found at the corresponding sequence position in other 2-oxoglutarate-dependent enzymes. The mutant enzymes were expressed in E. coli and purified to homogeneity. The catalytic activities of [Thr290]FHT and [Ala290]FHT were still significant, albeit greatly reduced to 20 and 8%, respectively, in comparison to the wild-type enzyme, whereas the activity of [Val290]FHT was negligible (about 1%). Kinetic analyses of purified wild-type and mutant enzymes revealed the functional significance of Ser290 for 2-oxoglutarate-binding. The spatial configurations of the related Fe(II)-dependent isopenicillin N and deacetoxycephalosporin C synthases have been reported recently and provide the lead structures for the conformation of other dioxygenases. Circular dichroism spectroscopy was employed to compare the conformation of pure flavanone 3beta-hydroxylase with that of isopenicillin N synthase. A double minimum in the far ultraviolet region at 222 nm and 208-210 nm and a maximum at 191-193 nm which are characteristic for alpha-helical regions were observed, and the spectra of the two dioxygenases fully matched revealing their close structural relationship. Furthermore, the spectrum remained unchanged after addition of either ferrous ions, 2-oxoglutarate or both of these cofactors, ruling out a significant conformational change of the enzyme on cofactor-binding.

A new method for extracting wooden foreign bodies from the upper esophagus.

A foreign body impacted in the esophagus is an emergency case that requires immediate treatment. Often the foreign body can be removed easily using forceps or loops. Sometimes, however, safe grasping and extraction may become very difficult. A patient swallowed a chestnut which then stuck in the upper esophagus. The chestnut was removed with a gynecological instrument with a spiral tip used for myoma fixation. Thereafter this technique was applied to in vitro tests with various kinds of meat and wood. In the clinical case, the chestnut could be removed with the spiral tip of the instrument for myoma fixation, whereas in the in vitro tests it was impossible to grasp meat or cut it into pieces. The removal of foreign bodies, such as wood, with the spiral tip of the instrument for myoma fixation during rigid esophagoscopy is an alternative to extraction with forceps or loops. This method is ineffective for the removal of pieces of meat.

Indole alkaloid biosynthesis in Catharanthus roseus: new enzyme activities and identification of cytochrome P450 CYP72A1 as secologanin synthase.

The molecular characterization of CYP72A1 from Catharanthus roseus (Madagascar periwinkle) was described nearly a decade ago, but the enzyme function remained unknown. We now show by in situ hybridization and immunohistochemistry that the expression in immature leaves is epidermis-specific. It thus follows the pattern previously established for early enzymes in the pathway to indole alkaloids, suggesting that CYP72A1 may be involved in their biosynthesis. The early reactions in that pathway, i.e. from geraniol to strictosidine, contain several candidates for P450 activities. We investigated in this work two reactions, the conversion of 7-deoxyloganin to loganin (deoxyloganin 7-hydroxylase, DL7H) and the oxidative ring cleavage converting loganin into secologanin (secologanin synthase, SLS). The action of DL7H has not been demonstrated in vitro previously, and SLS has only recently been identified as P450 activity in one other plant. We show for the first time that both enzyme activities are present in microsomes from C. roseus cell cultures. We then tested whether CYP72A1 expressed in E. coli as a translational fusion with the C. roseus P450 reductase (P450Red) has one or both of these activities. The results show that CYP72A1 converts loganin into secologanin.