Effectiveness of endoscopic surgery training for medical students using a virtual reality simulator versus a box trainer: a randomized controlled trial.

BACKGROUND: The first step toward increasing the level of patient safety in endoscopic surgery is for all endoscopic surgeons to acquire fundamental skills, including psychomotor skills, in the preoperation stage of training. The current study aimed to evaluate the effectiveness of virtual reality (VR) simulator training and box training for training the fundamental skills of endoscopic surgery. METHODS: For this study, 35 medical students at Kyushu University were divided into three groups: simulator (SIM) group (n = 20), box trainer (BOX) group (n = 20), and control group (n = 15). None of the students had any experience assisting with endoscopic surgery or any previous training for endoscopic surgery. The students in the SIM group underwent training using a VR simulator, the Procedicus MIST, 2 h per day for 2 days. The students in the BOX group underwent training using a box trainer 2 h per day for 2 days. The students in the control group watched an educational video for 30 min. The endoscopic surgical skills of all the students were evaluated before and after training with a task of suturing and knot tying using a box trainer. RESULTS: Although no significant differences were found between the three groups in the total time taken to complete the evaluation task before training, there were significant improvements in the SIM and BOX groups after training compared with the control group. Box training increased errors during the task, but simulator training did not. CONCLUSION: The findings showed that box training and VR training have different outcomes. The authors expect that the best curriculum for their training center would involve a combination that uses the merits of both methods.

Laparoscopic cholecystectomy using a newly developed laparoscope manipulator for 10 patients with cholelithiasis.

BACKGROUND: Laparoscopic surgery has continued to gain popularity in almost all fields of abdominal surgery, and robotic systems have been introduced in general surgery. Naviot is a new remote-controlled laparoscope manipulator system controlled by the operator's hand. This study assessed its introduction into clinical practice. METHODS: A group of 10 consecutive patients with cholelithiasis underwent laparoscopic cholecystectomy assisted by the Naviot system (Naviot group). Another group of 41 patients who underwent laparoscopic cholecystectomy with a conventional human camera holder (human camera group) were selected for a comparison of their operative results with those of the Naviot group. RESULTS: The operative time of 89.3 +/- 27.1 min for the Naviot group was significantly longer than that of 74.8 +/- 28.1 min for the human camera group (p < 0.05). However, when the setup time for the Naviot system was excluded, the operative time was not significantly different from that for the human camera group. Other operative results showed no significant difference between the two groups. CONCLUSIONS: The authors believe that the new Naviot system is feasible for clinical use, and that it enables surgeons to perform solo gastrointestinal surgery.

Ca(2+)-induced switching of troponin and tropomyosin on actin filaments as revealed by electron cryo-microscopy.

Muscle contraction is regulated by the intracellular Ca(2+ )concentration. In vertebrate striated muscle, troponin and tropomyosin on actin filaments comprise a Ca(2+)-sensitive switch that controls contraction. Ca(2+ )binds to troponin and triggers a series of changes in actin-containing filaments that lead to cyclic interactions with myosin that generate contraction. However, the precise location of troponin relative to actin and tropomyosin and how its structure changes with Ca(2+ )have been not determined. To understand the regulatory mechanism, we visualized the location of troponin by determining the three-dimensional structure of thin filaments from electron cryo-micrographs without imposing helical symmetry to approximately 35 A resolution. With Ca(2+), the globular domain of troponin was gourd-shaped and was located over the inner domain of actin. Without Ca(2+), the main body of troponin was shifted by approximately 30 A towards the outer domain and bifurcated, with a horizontal branch (troponin arm) covering the N and C-terminal regions of actin. The C-terminal one-third of tropomyosin shifted towards the outer domain of actin by approximately 35 A supporting the steric blocking model, however it is surprising that the N-terminal half of tropomyosin shifted less than approximately 12 A. Therefore tropomyosin shifted differentially without Ca(2+). With Ca(2+), tropomyosin was located entirely over the inner domain thereby allowing greater access of myosin for force generation. The interpretation of three-dimensional maps was facilitated by determining the three-dimensional positions of fluorophores labelled on specific sites of troponin or tropomyosin by applying probabilistic distance geometry to data from fluorescence resonance energy transfer measurements.

Structural basis for the higher Ca(2+)-activation of the regulated actin-activated myosin ATPase observed with Dictyostelium/Tetrahymena actin chimeras.

Replacement of residues 228-230 or 228-232 of subdomain 4 in Dictyostelium actin with the corresponding Tetrahymena sequence (QTA to KAY replacement: half chimera-1; QTAAS to KAYKE replacement: full chimera) leads to a higher Ca(2+)-activation of the regulated acto-myosin subfragment-1 ATPase activity. The ratio of ATPase activation in the presence of tropomyosin-troponin and Ca(2+) to that without tropomyosin-troponin becomes about four times as large as the ratio for the wild-type actin. To understand the structural basis of this higher Ca(2+)-activation, we have determined the crystal structures of the 1:1 complex of Dictyostelium mutant actins (half chimera-1 and full chimera) with gelsolin segment-1 to 2.0 A and 2.4 A resolution, respectively, together with the structure of wild-type actin as a control. Although there were local changes on the surface of the subdomain 4 and the phenolic side-chain of Tyr230 displaced the side-chain of Leu236 from a non-polar pocket to a more solvent-accessible position, the structures of the actin chimeras showed that the mutations in the 228-232 region did not introduce large changes in the overall actin structure. This suggests that residues near position 230 formed part of the tropomyosin binding site on actin in actively contracting muscle. The higher Ca(2+)-activation observed with A230Y-containing mutants can be understood in terms of a three-state model for thin filament regulation in which, in the presence of both Ca(2+) and myosin heads, the local changes of actin generated by the mutation (especially its phenolic side-chain) facilitate the transition of thin filaments from a "closed" state to an "open" state. Between 394 and 469 water molecules were identified in the different structures and it was found that actin recognizes hydrated forms of the adenine base and the Ca ion in the nucleotide binding site.

Human type II phospholipase A2-induced Mac-1 expression on human neutrophils.

To investigate the effect of type II phospholipase A2 (PLA2-II) on neutrophil function, we assessed the Mac-1 (CD11b/CD18) expression on human neutrophils by flow cytometry after incubation of the cells with human PLA2-II. PLA2-II at a concentration of 10 microg/mL increased the Mac-1 expression by 150% compared with unstimulated cells at 30 min and after. Under these conditions PLA2-II increased the exocytosis from secretory vesicles but not from azurophilic, specific, or gelatinase granules. The results suggest that PLA2-II induces translocation of Mac-1 from the secretory vesicles to the plasma membrane. The Mac-1 induction mediated by PLA2-II was inhibited by an anti-PLA2-II antibody, which was able to inhibit the catalytic activity. However, the Mac-1 induction by PLA2-II was not inhibited by a 5-lipoxygenase, cyclooxygenase inhibitor, or a platelet-activating factor antagonist. Thus, we examined the effects of fatty acids and lysophospholipids on Mac-1 expression. Only arachidonic acid induced Mac-1 expression. These results imply that PLA2-II induces Mac-1 expression on neutrophils via production of arachidonic acid.

Chromosome of the enterohemorrhagic Escherichia coli O157:H7; comparative analysis with K-12 MG1655 revealed the acquisition of a large amount of foreign DNAs.

A complete Xba I and Bln I cleavage map was constructed for the chromosome of an enterohemorrhagic Escherichia coli (EHEC) O157:H7 strain isolated from an outbreak in Sakai City, Japan, in 1996. A comparative chromosome analysis with E. coli K-12 strain MG1655 was made. The EHEC chromosome was approximately 5600 kb in length, 1 Mb larger than that of MG1655. Despite the marked difference in chromosome length, the location and direction of seven rRNA operons of the EHEC strain were similar to those for MG1655. Overall organization of genes common in both strains is also highly conserved. Chromosome expansion was observed throughout the EHEC chromosome, albeit in an uneven manner. A large portion of the chromosome enlargement was observed in the region surrounding the replication terminus, particularly in a segment containing the terA locus. Sample sequencing of 3627 random shotgun clones suggested the presence of approximately 1550 kb strain-specific DNAs on the EHEC chromosome, most of which are likely to be of foreign origin.

Complete genome sequence of enterohemorrhagic Escherichia coli O157:H7 and genomic comparison with a laboratory strain K-12.

Escherichia coli O157:H7 is a major food-borne infectious pathogen that causes diarrhea, hemorrhagic colitis, and hemolytic uremic syndrome. Here we report the complete chromosome sequence of an O157:H7 strain isolated from the Sakai outbreak, and the results of genomic comparison with a benign laboratory strain, K-12 MG1655. The chromosome is 5.5 Mb in size, 859 Kb larger than that of K-12. We identified a 4.1-Mb sequence highly conserved between the two strains, which may represent the fundamental backbone of the E. coli chromosome. The remaining 1.4-Mb sequence comprises of O157:H7-specific sequences, most of which are horizontally transferred foreign DNAs. The predominant roles of bacteriophages in the emergence of O157:H7 is evident by the presence of 24 prophages and prophage-like elements that occupy more than half of the O157:H7-specific sequences. The O157:H7 chromosome encodes 1632 proteins and 20 tRNAs that are not present in K-12. Among these, at least 131 proteins are assumed to have virulence-related functions. Genome-wide codon usage analysis suggested that the O157:H7-specific tRNAs are involved in the efficient expression of the strain-specific genes. A complete set of the genes specific to O157:H7 presented here sheds new insight into the pathogenicity and the physiology of O157:H7, and will open a way to fully understand the molecular mechanisms underlying the O157:H7 infection.

Complete nucleotide sequences of 93-kb and 3.3-kb plasmids of an enterohemorrhagic Escherichia coli O157:H7 derived from Sakai outbreak.

Enterohemorrhagic Escherichia coli (EHEC) O157:H7, derived from an outbreak in Sakai city, Japan in 1996, possesses two kinds of plasmids: a 93-kb plasmid termed pO157, found in clinical EHEC isolates world-wide and a 3.3-kb plasmid termed pOSAK1, prevalent in EHEC strains isolated in Japan. Complete nucleotide sequences of both plasmids have been determined, and the putative functions of the encoded proteins and the cis-acting DNA sequences have been analyzed. pO157 shares strikingly similar genes and DNA sequences with F-factor and the transmissible drug-resistant plasmid R100 for DNA replication, copy number control, plasmid segregation, conjugative functions and stable maintenance in the host, although it is defective in DNA transfer by conjugation due to the truncation and deletion of the required genes and DNA sequences. In addition, it encodes several proteins implicated in EHEC pathogenicity such as an EHEC hemolysin (HlyA), a catalase-peroxidase (KatP), a serine protease (EspP) and type II secretion system. pOSAK1 possesses a ColE1-like replication system, and the DNA sequence is extremely similar to that of a drug-resistant plasmid, NTP16, derived from Salmonella typhimurium except that it lacks drug resistance transposons.

Nested genomic structure of haploid germ cell specific haspin gene.

The haspin gene specifically expressed in haploid germ cells encodes a unique Ser/Thr protein kinase. We have cloned a mouse haspin genomic clone using cDNA as a probe. Sequencing data showed that the haspin gene was not interrupted by introns and was bordered by appropriate direct repeat. The transcription start site of the gene was not preceded by a TATA box. The whole transcription unit was located at an intron of integrin alphaM290 gene, and transcription direction of these two genes was different. Southern blotting analysis under stringent condition showed that haspin was a single gene. Phylogenetic analysis suggested that the diversion of haspin gene from other kinase family might be very ancient: the early stage of plant-fungus-animal split.

Genomic analysis of male germ cell-specific actin capping protein alpha.

The Gsg3 gene which expresses specifically in haploid germ cells is a mouse testicular homolog of somatic cell type actin capping protein alpha (ACP alpha). We have obtained a mouse Gsg3 genomic clone using cDNA as a probe. Sequencing data showed that the Gsg3 gene was not interrupted by introns. The transcription initiation site of the gene was preceded not by a TATA box or GC rich promoter motifs, but by two consensus cAMP-response element (CRE) motifs at the putative position. Southern blotting analysis showed that Gsg3 is a single copy gene in the mouse, and conserved in mammals. Phylogenetic analysis showed that Gsg3 is a novel ACP alpha specific for haploid germ cells.

Complete nucleotide sequence of the prophage VT1-Sakai carrying the Shiga toxin 1 genes of the enterohemorrhagic Escherichia coli O157:H7 strain derived from the Sakai outbreak.

Shiga toxins 1 and 2 (Stx1 and Stx2) are encoded by prophages lysogenized in enterohemorrhagic Escherichia coli (EHEC) O157:H7 strains. Lytic growth of the phage particles carrying the stx1 genes (stx1A and stx1B) of the EHEC O157:H7 strain RIMD 0509952, which was derived from the Sakai outbreak in 1996 in Japan, was induced after treatment with mitomycin C, but the plaque formation of the phage was not detected. We have determined the complete nucleotide sequence of the prophage VT1-Sakai. The integration site of the prophage was identified within the yehV gene at 47.7 min on the chromosome. The stx1 genes were downstream of the Q gene in the prophage genome, suggesting that their expression was regulated by the Q protein, the regulator of the late gene expression of the phage, which is similar to that of the stx1 or stx2 genes carried by the lambdoid phages reported previously. The sequences of the N gene and its recognition sites, nutL and nutR, were not homologous to those of the phages carrying the stx genes thus far reported, but they were very similar to those of bacteriophage phi21. The sequences of the repressor proteins, CI and Cro, that regulate expression of the early genes had low similarities with those of the known repressors of other phages, and their operator sequences were different from any sequence reported. These data suggest that multiple genetic recombination among bacteriophages with different immunities took place to generate the prophage VT1-Sakai. Comparison between the sequences of VT1-Sakai and lambda suggests that the ancestor of VT1-Sakai was produced by illegitimate excision, like lambda gal and bio phages.

Protease gene structure and env gene variability of the AIDS virus.

The protease gene structure and the env gene variability have been precisely compared between the AIDS virus and members of the HTLV/BLV family. The conserved amino acid sequence (LVDT) which is repeated in the proteases of the HTLV/BLV family is not repeated in AIDS virus. Comparative analysis of the env gene sequences reveals the striking fact that the env gene of AIDS virus is 8-12-times more variable than those of the HTLV/BLV family. Within the AIDS virus env gene, the surface glycoprotein region is more liable to vary than is the transmembrane region; unexpectedly, however, this liability is not a characteristic feature of the AIDS virus because it is more prominent in other retroviruses including members of the HTLV/BLV family.

Two distinct polypeptides may be translated from a single spliced mRNA of the X genes of human T-cell leukemia and bovine leukemia viruses.

Human T-cell leukemia and bovine leukemia viruses have a potential transforming gene, termed X. In addition to the major open reading frame known to encode a functional protein, the X gene harbors another short open reading frame which overlaps this major one. Both of these open reading frames are found on a single spliced X mRNA in a potentially functional form. Circumstantial evidence strongly suggests that they are both translated from the single X mRNA molecule, showing striking similarity to the translation mechanism of an adenovirus Elb gene mRNA. We note that the short open reading frame has the capability to encode a putative nuclear protein with structural features similar to those of an AIDS virus trans-acting protein.

Identification of a potential protease-coding gene in the genomes of bovine leukemia and human T-cell leukemia viruses.

The genomes of bovine leukemia and human T-cell leukemia viruses both contain an unidentified region between the gag and pol genes. These regions harbor an open reading frame that is in a different phase from the reading frames of the gag and pol genes. Based on the deduced amino acid sequences, we show here that they potentially encode a gag precursor-cleaving protease, which is known to be fused to the gag and pol products of avian and murine retroviruses, respectively. This finding raises the interesting question of the expression and evolution of retroviral genes.

One of the retinoic acid-inducible cDNA clones in mouse embryonal carcinoma F9 cells encodes a novel isoenzyme of fructose 1,6-bisphosphatase.

Rae-30, one of the retinoic acid (RA)-inducible cDNA clones in mouse embryonal carcinoma F9 cells, was sequenced and the deduced RAE-30 protein showed about a 70% homology to mammalian fructose 1,6-bisphosphatase (EC 3.1.3.11) (FBPase), in comparison to over 85% homology observed among the previously documented rat liver, pig kidney and human leukemic HL-60 cell FBPases. The Rae-30 mRNAs were not detected in various tissues of adult mice, including the liver and kidney, but were detected in a placenta and predominantly in the intestine of adult mice. These findings indicate that the Rae-30 cDNA encodes a novel isoenzyme of FBPase, which is likely to be involved in early differentiation in mammalian cells.

Radiation therapy of invasive thymoma.

Between 1978 and 1987, 30 cases of invasive thymomas were treated with radiotherapy after surgery. Surgical therapy consisted of total resection in 15 patients, subtotal resection in 1 patient, and biopsy in 14 patients. Myasthenia gravis (MG) was associated in nine patients (MG(+) group), but in 21 patients there was no evidence of myasthenia gravis (MG(-) group). Irradiation in the dose range of 30 to 58.7 Gy was delivered. The total average 5-year survival rate was 71.8%; it was 39.2% in MG(+) group and 78.3% in MG(-) group, though there was no significant statistical difference. Myasthenia gravis was well controlled by the tumorectomy and associated radiotherapy in 7 of the 9 patients. However, in 3 of 7 patients (42.9%) myasthenia gravis recurred at 2 years, 2 years and 7 months, and 5 years and 8 months after initial therapy. Total body irradiation of 2 Gy with 0.1 Gy fractions was administered for uncontrollable myasthenia gravis in one patient with marked improvement. Radiation therapy is an important therapeutic modality for unresectable malignant thymoma as well as for postoperative combined therapy. Total body irradiation may be an effective method to treat patients with otherwise resistant myasthenia gravis.

Radiotherapy of spontaneous carotid-cavernous sinus fistulas.

Between 1984 and 1986, 7 patients with spontaneous carotid-cavernous fistulas (CCF) were treated by radiotherapy delivering 3,000 cGy (200 cGy, 5 times per week) to the sellar region. Improvements of clinical signs and symptoms were seen in all patients within 6 months of treatment. During a follow-up period of 7 to 35 months, 6 patients remained in good clinical condition and only one patient developed a recurrence. As an adverse effect, one patient developed early menopause, but no other side-effects or complications were seen. Radiotherapy should be considered in patients with spontaneous CCF, when CCF are seen in middle-high aged patients and progressive without relief of symptoms.

N-[2-[(substituted chroman-8-yl)oxy]ethyl]-4-(4-methoxyphenyl)butylamines: synthesis and wide range of antagonism at the human 5-HT1A receptor.

A series of N-[2-[(substituted chroman-8-yl)oxy]ethyl]-4-(4-methoxyphenyl)butylamines was prepared and examined for their 5-HT1A receptor antagonist activity. The parent compound 3a and seven analogs bearing five kinds of substituents on the chroman ring were prepared from the corresponding 8-hydroxychroman intermediates. Radioligand binding assays proved the compounds 3a-h to have high affinity for the rat hippocampal 5-HT1A receptor with varied selectivity for adrenaline alpha1 and dopamine D2 receptors. Their antagonism was evaluated in a forskolin-stimulated adenylate cyclase assay performed with CHO cells expressing the human 5-HT1A receptor. Among the series, the C6-fluoro analog 3c showed both extremely potent affinity (Ki = 0.22 nM) and antagonism (EC50 = 13 nM) for the 5-HT1A receptor. Correlation analysis using substituent descriptors revealed a linear and negative correlation between molar refractivity of the C6-substituent and the binding affinity expressed in pKi.

Synthesis and pharmacological characterization of novel 6-fluorochroman derivatives as potential 5-HT1A receptor antagonists.

A series of novel 6-fluorochroman derivatives was prepared and evaluated as antagonists for the 5-HT1A receptor. N-2-[[(6-Fluorochroman-8-yl)oxy]ethyl]-4-(4-methoxyphenyl)butylami ne (3; J. Med. Chem. 1997, 40, 1252-1257) was chosen as a lead, and structural modifications were done on the aliphatic portion of the chroman ring, the tether linking the middle amine and the terminal aromatic ring, the aromatic ring, and lastly the amine. Radioligand binding assays proved that the majority of the novel compounds behaved as good to excellent ligands at the 5-HT1A receptor, some of which were selective with respect to alpha1-adrenergic and D2-dopaminergic receptors. The antagonist activity of the compounds was assessed in the forskolin-stimulated adenylate cyclase assays in CHO cells expressing the human 5-HT1A receptors. Among the modifications attempted, introduction of an oxo or an optically active hydroxy moiety at the chroman C-4 position was effective in ameliorating the receptor selectivity. Six analogues were selected through the in vitro screens and further evaluated for their in vivo activities. A 4-oxochroman derivative (31n), having a terminal 1, 3-benzodioxole ring, demonstrated antagonist activities toward 8-OH-DPAT-induced behavioral and electrophysiological responses in rats.

Biodegradation behavior of ultra-high-strength hydroxyapatite/poly (L-lactide) composite rods for internal fixation of bone fractures.

The purpose of this study was to investigate the biodegradation behavior of the ultra-high-strength hydroxyapatite/poly(L-lactide) (HA/PLLA) composite rods for fracture repair. Two kinds of composite materials were used in this study: u-HA/PLLA. which contained 30% by weight of uncalcined HA as reinforcing particles, and c-HA/PLLA, which contained 30% by weight of calcined HA as reinforcing particles. These composite rods were implanted in the subcutis and in the medullary cavities of rabbits. The specimens were removed at specific intervals between 2 and 52 weeks and the mechanical strength was measured for the rods in the subcutis, and the molecular weight and crystallinity were measured for the rods in both the subcutis and medullary cavities. The rod surfaces were examined using a scanning electron microscope (SEM). The specimens were examined histologically by light microscopy. The bending strength of the composites implanted in the subcutis was maintained at more than 200 M Pa at 25 weeks and at 150 MPa at 52 weeks. The molecular weight dropped to 45% of the initial values at 8 weeks and to approximately 10% at 52 weeks. Significant differences in the molecular weight were seen between c-HA/PLLA and u-HA/PLLA, with u-HA/PLLA showing a faster rate of decrease than c-HA/PLLA after 8 weeks. SEM demonstrated that HA particles disappeared increasingly from the rod surfaces over time and that the spaces left by these HA particles formed many pores in the composite surfaces at 52 weeks. Histologically, a fibrous tissue layer was formed around the composite rod from 4 weeks in the subcutis and in the diaphyseal area of the medullary canal. This became more mature over time. Bony tissue contact to the composites without fibrous tissue layers was seen in the metaphyseal area of the medullary canal. During the experimental period, there were no inflammatory cells such as mono- or multi-nuclear phagocytes. Although further long-term studies for degradation are needed, the composites have promising mechanical strength and no adverse tissue reaction for use as fracture-fixation devices during the experimental periods.