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.

Conditioning of Parsley (Petroselinum crispum L.) Suspension Cells Increases Elicitor-Induced Incorporation of Cell Wall Phenolics.

The elicitor-induced incorporation of phenylpropanoid derivatives into the cell wall and the secretion of soluble coumarin derivatives (phytoalexins) by parsley (Petroselinum crispum L.) suspension cultures can be potentiated by pretreatment of the cultures with 2,6-dichloroisonicotinic acid or derivatives of salicylic acid. To investigate this phenomenon further, the cell walls and an extracellular soluble polymer were isolated from control cells or cells treated with an elicitor from Phytophthora megasperma f. sp. glycinea. After alkaline hydrolysis, both fractions from elicited cells showed a greatly increased content of 4-coumaric, ferulic, and 4-hydroxybenzoic acid, as well as 4-hydroxybenzaldehyde and vanillin. Two minor peaks were identified as tyrosol and methoxytyrosol. The pretreatment effect is most pronounced at a low elicitor concentration. Its specificity was elaborated for coumarin secretion. When the parsley suspension cultures were preincubated for 1 d with 2,6-dichloroisonicotinic, 4- or 5-chlorosalicylic, or 3,5- dichlorosalicylic acid, the cells exhibited a greatly increased elicitor response. Pretreatment with isonicotinic, salicylic, acetylsalicylic, or 2,6-dihydroxybenzoic acid was less efficient in enhancing the response, and some other isomers were inactive. This increase in elicitor response was also observed for the above-mentioned monomeric phenolics, which were liberated from cell walls upon alkaline hydrolysis and for "lignin-like" cell wall polymers determined by the thioglycolic acid method. It was shown for 5-chlorosalicylic acid that conditioning most likely improves the signal transduction leading to the activation of genes encoding phenylalanine ammonia lyase and 4-coumarate: coenzyme A ligase. The conditioning thus sensitizes the parsley suspension cells to respond to lower elicitor concentrations. If a similar mechanism were to apply to whole plants treated with 2,6-dichloroisonicotinic acid, a known inducer of systemic acquired resistance, one can hypothesize that fungal pathogens might be recognized more readily and effectively.

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.

Different types of microsomal enzymes catalyze ortho- or para-hydroxylation in the biosynthesis of carnation phytoalexins.

Cell suspension cultures of carnation (Dianthus caryophyllus L.) accumulate, upon challenge with crude fungal elicitor, various dianthramide phytoalexins, all of which derive from N-benzoylanthranilate. In vitro, microsomes from the elicited carnation cells hydroxylated N-benzoylanthranilate in the 4- and/or 2'-positions to yield the hydroxyanthranilate and/or salicyloyl derivatives. 2'-Hydroxylation was shown to precede 4-hydroxylation in the formation of N-salicyloyl-4-hydroxyanthranilate, and both these activities depended strictly on NADPH and molecular oxygen. 4-Hydroxylation was shown to be catalyzed by cytochrome P-450-dependent monooxygenase(s), whereas the 2'-hydroxylating activity appeared to be due to a novel class of enzymes, also responding synergistically to NADH in combination with NADPH and showing apparent inhibition by cytochrome c but not by carbon monoxide. The difference in type of 4- and 2'-hydroxylases was corroborated by the exclusive inhibition of either activity in imidazole vs. MOPS buffers as well as their differential heat sensitivities. In the course of these studies, low concentrations of N-salicyloylanthranilate turned out to inhibit the cytochrome P-450-dependent 4-hydroxylation more strongly than any of the commercial inhibitor chemicals tested, while neither the substrate, N-benzoylanthranilate, nor the final product, N-salicyloyl-4-hydroxyanthranilate, exhibited such significant inhibition. In addition, 2'-hydroxylation activity was affected much less by N-benzoylanthranilate, N-salicyloylanthranilate or by inhibitor chemicals. The results demonstrate the requirement of two different classes of hydroxylase activities that appear to introduce the antimycotic quality to the dianthramides for phytoalexin defense.

Biosynthesis of psoralens. Psoralen 5-monooxygenase activity from elicitor-treated Ammi majus cells.

Microsomes prepared from cultured Ammi majus cells that had been challenged for 14 h with an elicitor derived from the cell walls of Phytophthora megasperma f.sp. glycinea (Pmg) converted psoralen to bergaptol (5-hydroxypsoralen) in the presence of NADPH and oxygen. The enzymatic activity was characterized as an inducible cytochrome-P-450-dependent monooxygenase associated with the endoplasmic reticulum. All of the steps involved in bergapten (5-methoxypsoralen) biosynthesis in Ammi majus have now been demonstrated in vitro. The results suggest that bergaptol and not hydroxymarmesin in the precursor of bergapten.

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.

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.

Detoxification of the macrolide toxin brefeldin A by Bacillus subtilis.

The macrolide toxin brefeldin A is a determinant of Alternaria leaf blight disease in safflower, which causes severe economic losses worldwide. Soilborne bacteria, classified as Bacillus subtilis spp., were isolated and shown to readily metabolize brefeldin A in laboratory culture to one major product. This product was identified by high resolution 2D 1H NMR and FAB mass spectroscopies as the acid resulting from hydrolysis of the macrolide ring in brefeldin A . In contrast to brefeldin A, the acid completely lacked phytotoxic activity in the standard leaf bioassay. Detoxification of brefeldin A by the lactonase activity from Bacillus subtilis may be exploited in the future to introduce resistance to Alternaria leaf blight in safflower.

Native acridone synthases I and II from Ruta graveolens L. form homodimers.

Acridone synthase II cDNA was cloned from irradiated cell suspension cultures of Ruta graveolens L. and expressed in Escherichia coli. The translated polypeptide of Mr 42,681 revealed a high degree of similarity to heterologous chalcone and stilbene synthases (70-75%), and the sequence was 94% identical to that of acridone synthase I cloned previously from elicited Ruta cells. Highly active recombinant acridone synthases I and II were purified to apparent homogeneity by a four-step purification protocol, and the affinities to N-methylanthraniloyl-CoA and malonyl-CoA were determined. The molecular mass of acridone synthase II was estimated from size exclusion chromatography on a Fractogel EMD BioSEC (S) column at about 45 kDa, as compared to a mass of 44 +/- 3 kDa found for the acridone synthase I on Superdex 75. Nevertheless, the sedimentation analysis by ultracentrifugation revealed molecular masses of 81 +/- 4 kDa for both acridone synthases. It is proposed, therefore, that the acridone synthases of Ruta graveolens are typical homodimeric plant polyketide synthases.

Rapid purification of the peptide toxins microcystin-LR and nodularin.

An isolation procedure was developed to provide within one day microcystin-LR, a cyclic heptapeptide toxin from Microcystis aeruginosa PCC 7806. After ODS (octadecylsilyl) solid phase extraction, the crude toxin fraction was chromatographed using a strong anion exchange column. The toxin was eluted with 0.02 M ammonium bicarbonate. An at least 95% purity was revealed on HPLC separation by monitoring at 214 nm. Application of the procedure to the cyclic pentapeptide toxin nodularin from Nodularia spumigena AV2 was examined.

Induction of two prenyltransferases for the accumulation of coumarin phytoalexins in elicitor-treated Ammi majus cell suspension cultures.

Two dimethylallyl diphosphate:umbelliferone dimethylallyltransferase (prenyltransferase) activities, catalysing the 6-prenylation and the 7-O-prenylation, respectively, of umbelliferone in the course of phytoalexin synthesis, increased in Ammi majus cell suspension cultures in response to elicitor treatment. Both enzyme activities were dependent on Mg2+ or Mn2+ with significant preference for Mg2+ in the 6-prenylation reaction. Whereas dark-grown cells did not contain these activities, both prenyltransferase activities were induced rapidly by the addition of elicitor reaching a first maximum after 10-14 hr and a second maximum beyond 30 hr. Other coumarin specific, elicitor-induced enzyme activities of A. majus cells, in contrast, showed only one maximum of activity within the 50 hr experimental period, while the pattern of induction of phenylalanine ammonia-lyase activity resembled that of the prenyltransferases with maxima at ca 8 hr and 20-30 hr. Preliminary data suggest that the apparent biphasic induction of these enzyme activities is due to post-translational enzyme modifications.

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.

Differential regulation and distribution of acridone synthase in Ruta graveolens.

Cell suspension cultures of Ruta graveolens L. accumulate polyketide metabolites such as acridone alkaloids and flavonoid pigments. Whereas flavonoid synthesis is induced by light, the production of alkaloids can be enhanced in dark-cultured cells by treatment with fungal elicitors. Acridone synthase (ACS) catalyzes the committed condensing reaction of acridone biosynthesis yielding 1,3-dihydroxy-N-methylacridone from N-methylanthraniloyl- and malonyl-CoAs. The reaction proceeds in a manner analogous to that of chalcone synthase (CHS) which catalyzes the first committed step in flavonoid biosynthesis and cDNA and protein sequences of Ruta ACS possess a high degree of sequence homology to heterologous CHSs. ACS transcript abundance and specific activity were monitored in cultured R. graveolens cells irradiated either continuously with white light or treated with fungal elicitor over a period of 24 h and found to increase transiently upon elicitor treatment and to decrease upon light irradiation. Immunodetection with a rabbit polyclonal ACS antiserum revealed that the amounts of ACS polypeptide decreased slightly in light-irradiated cells but increased in elicitor-treated Ruta cells. Fluorescence microscopy and tissue print hybridizations were employed to aid in localizing the sites of storage and biosynthesis of acridone alkaloids in Ruta plants. Yellow fluorescing alkaloids were detected particularly in root tissue adjacent to the rhizodermis, but also in the endodermis and vascular tissue of the hypocotyl. ACS transcript abundance in situ followed the same spatial pattern, indicating that the synthesis of acridones likely proceeds at all sites of deposition rather than exclusively in the root. Expression in planta and the induction response of ACS suggest that the alkaloids serve as phytoanticipins or phytoalexins in the defense of Ruta particularly to soil-borne pathogens or as feeding deterrents.

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.

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.

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.

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.

[Laparoscopic techniques in therapy of choledocholithiasis]. / Laparoskopische Techniken zur Therapie der Choledocholithiasis.

Several methods for therapy of common bile duct stones (CBDS) during laparoscopic cholecystectomy are available. After intraoperative cholangiography laparoscopic removal of CBDS can be achieved via the cystic duct or a choledochotomy using a thin cholangioscope, balloon catheters and Dormia baskets. Lithotripsy (electrohydraulic or laser) is necessary in presence of larger stones. Also combined procedures with intraoperative antegrade or retrograde papillotomy have been described. Published studies show that laparoscopic common bile duct exploration can be performed successfully by experienced surgeons. However, these procedures are demanding and time-consuming. Further evaluation is essential.