Minimally invasive right colectomy with transrectal natural orifice extraction: could this be the next step forward?

BACKGROUND: The transvaginal natural orifice specimen extraction (NOSE) approach for right-side colon surgery has been proven to exhibit favorable short-term outcomes. However, thus far, no study has reported the advantages of transrectal NOSE for right-side colon surgery. The aim of this study was to compare the technical feasibility, safety, and short-term outcomes of minimally invasive right hemicolectomy using the transrectal NOSE method and those of conventional mini-laparotomy specimen extraction. METHODS: A study was conducted on consecutive patients who had minimally invasive right hemicolectomy either for malignancy or benign disease at Chang Gung Memorial Hospital, Linkou, Taiwan, between January 2017 and December 2018. The patients were divided into two groups: conventional surgery with specimen extraction using mini-laparotomy and NOSE surgery. Surgical outcomes, including complications, postoperative short-term recovery, and pain intensity, were analyzed. RESULTS: We enrolled 297 patients (151 males, mean age 64.9 ± 12.8 years) who had minimally invasive right hemicolectomy. Of these 297 patients, 272 patients had conventional surgery with specimen extraction through mini-laparotomy and 25 patients had NOSE surgery (23 transrectal, 2 transvaginal). The diagnosis of colon disease did not differ significantly between the conventional and NOSE groups. Postoperative morbidity and mortality rates were comparable. The postoperative hospital stay was significantly (p = 0.004) shorter in the NOSE group (median 5 days, range 3-17 days) than in the conventional group (median 7 days, range 3-45 days). Postoperative pain was significantly (p = 0.026 on postoperative day 1 and p = 0.002 on postoperative day 2) greater in the conventional group than in the NOSE group. CONCLUSIONS: NOSE was associated with acceptable short-term surgical outcomes that were comparable to those of conventional surgery. NOSE results in less postoperative wound pain and a shorter hospital stay than conventional surgery. Larger studies are needed.

In vitro methionine oxidation of Escherichia coli-derived human stem cell factor: effects on the molecular structure, biological activity, and dimerization.

The effect of oxidation of the methionine residues of Escherichia coli-derived recombinant human stem cell factor (huSCF) to methionine sulfoxide on the structure and activity of SCF was examined. Oxidation was performed using hydrogen peroxide under acidic conditions (pH 5.0). The kinetics of oxidation of the individual methionine residues was determined by quantitation of oxidized and unoxidized methionine-containing peptides, using RP-HPLC of Asp-N endoproteinase digests. The initial oxidation rates for Met159, Met-1, Met27, Met36, and Met48 were 0.11 min-1, 0.098 min-1, 0.033 min-1, 0.0063 min-1, and 0.00035 min-1, respectively, when SCF was incubated in 0.5% H2O2 at room temperature. Although oxidation of these methionines does not affect the secondary structure of SCF, the oxidation of Met36 and Met48 affects the local structure as indicated by CD and fluorescence spectroscopy. The 295-nm Trp peak in the near-UV CD is decreased upon oxidation of Met36, and lost completely following the oxidation of Met48, indicating that the Trp44 environment is becoming significantly less rigid than it is in native SCF. Consistent with this result, the fluorescence spectra revealed that Trp44 becomes more solvent exposed as the methionines are oxidized, with the hydrophobicity of the Trp44 environment decreasing significantly. The oxidations of Met36 and Met48 decrease biological activity by 40% and 60%, respectively, while increasing the dissociation rate constant of SCF dimer by two- and threefold. These results imply that the oxidation of Met36 and Met48 affects SCF dimerization and tertiary structure, and decreases biological activity.

S-carbobenzoxyglutathione: a competitive inhibitor of mammalian glyoxalase II.

An effective competitive inhibitor of mammalian glyoxalase II has been synthesized and studied. The compound, S-carbobenzoxyglutathione, is almost totally inactive as an inhibitor of mammalian glyoxalase I. This is in marked contrast to other glyoxalase II competitive inhibitors, which in general are even more effective against glyoxalase I. S-Carbobenzoxyglutathione has found utility as an affinity ligand for the purification of rat liver glyoxalase II, and it may well have use in the study of the glyoxalase enzymes in vivo.

Comparison of N-linked oligosaccharides of recombinant human tissue kallikrein produced by Chinese hamster ovary cells on microcarrier beads and in serum-free suspension culture.

Glycosylation heterogeneity in recombinant human tissue kallikrein (r-HuTK) produced by Chinese hamster ovary (CHO) cells from microcarrier culture and from a serum-free suspension cell recycle process has been compared. Significant differences in the degree of sialylation were observed in glycoform distribution and oligosaccharide heterogeneity. High-performance liquid chromatography with a pellicular anion-exchange column under low pH eluant conditions was used to characterize the number and types of N-linked complex type oligosaccharides present. The oligosaccharides were released by N-glycanase and, after reduction, were resolved into a number of peaks containing one, two, three, and four sialic acids with an additional subfractionation based on the nature of the antennary structure. The microcarrier process resulted in a reduced amount of sialylated oligosaccharide species as compared to the suspension cell process. Removal of sialic acid followed by chromatography of the asialooligosaccharides under high pH anion-exchange conditions indicated that the same antennary structures were present but in slightly different relative amounts. The oligosaccharide profiles are indicative of a highly complex array of microheterogeneity present, encompassing mono-, di-, tri-, and tetrasialylated complex type oligosaccharides.

Multimeric forms of rat liver glyoxalase II.

Rat liver glyoxalase II has been purified to homogeneity by a rapid, two-step procedure involving affinity chromatography on S-carbobenzoxyglutathione coupled to Sepharose 4B. The purified enzyme gives a major band corresponding to 30,000 daltons (monomer) and a minor band corresponding to 120,000 daltons (tetramer) with sodium dodecylsulfate polyacrylamide gel electrophoresis. Evidence is given for the interconversion of the monomer and tetramer forms of glyoxalase II via the dimer and the trimer.

Structural studies on acid unfolding and refolding of recombinant human interferon gamma.

Interferon gamma is distinguished from other types of interferons in its instability upon acid treatment, as demonstrated by a loss of antiviral activity. Acid unfolding and refolding experiments were performed with recombinant DNA derived human interferon gamma. When the protein was subjected to unfolding and refolding, the refolded protein showed two peaks (peaks I and II) in gel filtration which have been shown to differ in size, structure, and antiviral activity. When the smaller, peak II, form was unfolded by dialysis against 0.01 M HCl containing 0.1 M NaCl (pH 2) and refolded by dialysis against various solvents at neutral pH, it re-formed as peak II but also generated peak I, and the ratio of the two forms was dependent on protein concentration and solvent conditions. Higher protein concentrations and higher ionic strength led to a greater ratio of peak I to peak II. Phosphate buffers caused precipitation of peak I. Since peak II is 4-8 times more active than peak I in the antiviral bioassay, generation of peak I by acid treatment of peak II should lead to a decrease in antiviral activity.

Acid unfolding and self-association of recombinant Escherichia coli derived human interferon gamma.

The secondary and tertiary structure of recombinant human interferon gamma, determined by far- and near-UV circular dichroism, showed a transition from the native state to an unfolded state below pH 4.5. The acid unfolding was extensively studied at pH 3.5 as a function of NaCl concentration. Addition of 0.05-0.2 M NaCl to a pH 3.5 sample increased the amount of beta-sheet structure with no change in the amount of alpha-helix and also induced reversible self-association of interferon gamma to form large aggregates from the monomer. When samples at pH 3.5 were dialyzed against 0.1 M ammonium acetate (pH 6.9) to refold interferon gamma, the samples that contained NaCl in acid formed aggregates upon dialysis while those without NaCl formed a dimer apparently identical with the starting protein (i.e., before acid treatment). Thus, the self-association of interferon gamma in acid is closely correlated with its aggregation behavior in 0.1 M ammonium acetate after removal of acid.

Metabolites of Bacillus sp. isolated from flax-suppressive soil.

A culture of Bacillus sp. was isolated from the suppressive flax soil. It could inhibit the growth of many plant pathogens that were found in suppressive flax soil, and an acidic ethyl acetate extract of culture broth of the isolated Bacillus showed significant inhibition of the growth of some plant pathogens. The antimicrobial activity of culture extracts (15 times concentrated) was higher than that of 400 micrograms/ml actidione or 200 micrograms/ml mycostatin (nystatin). The antimicrobial substances were relatively stable. After heating at 100 degrees C for 10 min. and 30 min., the activities were still 100% and 72%, respectively. Properties of the compounds were investigated by UV, TLC, GC and GCMS. The component with the retention time of 13.4 min in a gas chromatography was biologically active and the parent peak was at m/z 142.

Preparation and characterization of recombinant DNA-derived human interferon-gamma.

An attempt was made to prepare a highly purified, active recombinant DNA-derived human interferon-gamma. When the protein was denatured in urea and refolded, gel filtration and sedimentation velocity experiments indicated the presence of two forms, which are different in size and are not in a rapid reversible equilibrium. The two forms could be chromatographically separated. Far-UV circular dichroic spectra indicated the presence of secondary structures for both forms. Near-UV circular dichroic spectra revealed that the smaller form is folded into a rigid tertiary structure. The antiviral activity of the two forms of interferon-gamma showed a significant difference, i.e. the smaller form was 4-8-fold more active than the larger form. A variety of experiments show that the smaller form is more active, homogeneous, soluble, and stable than the larger form.

The McKusick-Kaufman hydrometrocolpos-polydactyly syndrome--a case report.

Hydrometrocolpos is a rare congenital anomaly and serious life threatening condition in the newborn infant due to its long-term compression sequelae and associated congenital anomalies. Prenatal diagnosis of hydrometrocolpos by sonogram allows appropriate management during the prenatal and neonatal period. The combination of hydrometrocolpos and polydactyly is the cardinal hallmark feature of McKusick-Kaufman Syndrome. We present a case of congenital hydrometrocolpos due to vaginal atresia combined with polydactyly of both feet, mild atrial septum defect, bilateral hydronephrosis, fetal ascites and polyhydramnios. Pathogenesis and treatment of hydrometrocolpos and its associated congenital anomalies are discussed.

Role of single disulfide in recombinant human tumor necrosis factor-alpha.

Two analogs of tumor necrosis factor-alpha (TNF-alpha) were produced by in vitro site-directed mutagenesis. In these analogs, cysteine residues at positions 69 and 101, which form a disulfide bond, were changed to alanine or leucine. CD spectra showed that the analogs are apparently similar in secondary and tertiary structure to the natural sequence TNF-alpha. In addition, the molecular size of the analogs was identical to that of the natural sequence TNF-alpha as determined by gel filtration. However, fluorescence spectra and quenching indicated that the removal of the disulfide bond alters the local conformation around tryptophan residues. The cytolytic, macrophage activation, and lipogenic activities decreased in the order of the natural sequence TNF-alpha greater than the alanine analog greater than the leucine analog, suggesting that the surface involving the disulfide bond plays a role in these biological functions and the introduced modifications decrease the activity. Differential effect of the modifications was suggested in the antiviral activity, since in this assay only the leucine analog showed significantly lower activity.

Role of polycationic C-terminal portion in the structure and activity of recombinant human interferon-gamma.

Purified recombinant human interferon-gamma, produced in Escherichia coli, was digested with trypsin under mild conditions, resulting in a preparation containing approximately 90% of a Mr = 15,800 protein and 10% of a 14,400 protein. The Mr = 15,800 protein has an intact N terminus and the Mr = 14,400 protein lacks 14 N-terminal residues. Both proteins lack C terminus of approximately 13 residues. This preparation containing the Mr = 15,800 and 14,400 proteins was identical with the intact protein with respect to conformation and dimerization, as analyzed by circular dichroism and gel filtration. However, the antiviral activity of this preparation was 1000-fold lower than that of the intact molecule. Since the majority of this preparation is the Mr = 15,800 protein, these results suggest that the C terminus does not affect the protein conformation and self-association, but greatly alters antiviral activity.

Detection and quantitation of recombinant granulocyte colony-stimulating factor charge isoforms: comparative analysis by cationic-exchange chromatography, isoelectric focusing gel electrophoresis, and peptide mapping.

Routine quantitation of recombinant human granulocyte colony-stimulating factor charge isoforms in the purified protein product requires development of a reliable analytical method. In this report, isoelectric focusing gel electrophoresis, peptide mapping, and cation-exchange high-performance liquid chromatography are compared and evaluated in the analysis of charge isomers that may be present in the recombinant factor. Due to a lack of sensitivity and reliability, isoelectric focusing gel electrophoresis and peptide mapping are not recommended. However, peptide mapping can distinguish aberrant peptides with differences in charges and provide separation for subsequent structural characterization. By this approach, an N-terminally blocked formylmethionyl species was identified to be the minor charge isoform in the purified preparations of recombinant human granulocyte colony-stimulating factor. In contrast to electrophoresis and peptide mapping, a strong cationic-exchange chromatographic procedure was found to be the most selective, sensitive, and reproducible analytical method. The sensitivity and reliability of the method were evaluated and validated using the formylmethionyl isoform and several deamidated analogs (Gln----Glu) made by site-directed mutagenesis. Recombinant human granulocyte colony-stimulating factor preparations contain a very low to undetectable level of the formylmethionine isoform and have no detectable deamidated isoforms.

Purification and characterization of human tissue prokallikrein and kallikrein isoforms expressed in Chinese hamster ovary cells.

We report here the expression of recombinant human prokallikrein and kallikrein in engineered Chinese hamster ovary cells transfected with a human genomic gene encoding preprokallikrein. At high expression levels, recombinant prokallikrein, an inactive proenzyme form, is predominantly secreted into the culture medium. Upon chromatographic separations, the inactive prokallikrein as well as the mature kallikrein after thermolysin activation of the proenzyme can be prepared to apparent purity. Both prokallikrein and kallikrein can be further separated into two distinct high- and low-molecular-weight isoforms. Kallikrein preparations are fully active in standard kallikrein activity assays such as esterase activity and kinin release from kininogen. Both kallikrein and prokallikrein display multiple molecular forms with differences in both molecular sizes and charges. The structural differences in high- and low-molecular-weight kallikreins or prokallikreins were found to be due to glycosylation, with the high-molecular-weight species glycosylated at three Asn-linked sites and the low-molecular-weight species at two of the three Asn-linked sites. The multiply charged kallikrein isoforms are derived from different numbers of sialic acids attached at the detected Asn-linked carbohydrates. In comparison with kallikrein, prokallikrein appears to show a significant decrease in the magnitude of near uv-circular dichroism bands, suggesting a change in local conformation. This conformational change correlates with the loss of activity in proenzyme due to the presence of propeptide.

Structure and activity of glycosylated human interferon-gamma.

Structural properties and activity of recombinant human interferon-gamma (IFN-gamma) purified from Chinese hamster ovary (CHO) cells or a natural source were determined and compared with those of Escherichia coli-derived IFN-gamma. One preparation of CHO-derived IFN-gamma showed three bands, with the middle band being a doublet, in a SDS-polyacrylamide gel. The two higher-molecular-weight bands were shown to be glycosylated. Western blot analysis indicated that the three bands are IFN-gamma and lack an intact carboxyl terminus. The circular dichroic (CD) spectra showed that conformation of the CHO-derived IFN-gamma is similar in the native state, in acid, and after renaturation from acid to the E. coli-derived IFN-gamma. These results indicate that neither glycosylation nor carboxy-terminal processing affects conformational properties of the protein, as detected by CD spectroscopy. However, the antiviral activity was fourfold lower for the preparation of CHO-derived IFN-gamma than for the E. coli-derived IFN-gamma. A different preparation or a natural IFN-gamma preparation with less extensive carboxy-terminal processing showed similar conformational properties and antiviral activity to the E. coli-derived IFN-gamma. These results indicate that the carboxyl terminus, but not glycosylation, plays an important role in the antiviral activity of IFN-gamma.

The effect of C-terminal processing on the activity of human interferon-gamma.

Homogeneous recombinant human interferon-gamma (IFN-gamma) obtained from Escherichia coli (E. coli) was treated with a protease-containing fraction prepared from mechanically lysed E. coli cells. Polyacrylamide gel electrophoresis of the resulting product revealed two major components of molecular weight less than that of intact IFN-gamma. These were purified by ion exchange chromatography in the presence of 7 M urea and shown to have intact IFN-gamma N-terminal sequences, suggesting that they resulted via C-terminal cleavages of IFN-gamma. Amino acid analysis indicated that 4 C-terminal residues of IFN-gamma were lacking in one, and 15 in the other. The species lacking 4 C-terminal residues had activities virtually indistinguishable from those of IFN-gamma in antiviral and growth inhibitory assays using Encepharomyocarditis-treated HeLa or T98G cells and in a macrophage activation assay using macrophage-like U937 cells. The species lacking 15 C-terminal residues had markedly decreased activities in each of these assays, and had decreased binding affinity for IFN-gamma cell surface receptors. These observations define the C-terminal residues important for IFN-gamma's biological activity--information which should be useful in designing analogs of IFN-gamma with enhanced or altered biological activities.

Characterization of a cysteine-free analog of recombinant human basic fibroblast growth factor.

Using oligo site-directed mutagenesis, we have modified our synthetic gene for human basic fibroblast growth factor (bFGF) to replace all four cysteine codons with serine codons. The corresponding protein was expressed in Escherichia coli and purified from inclusion bodies by solubilization in urea followed by a series of column chromatographies and a folding step. The resulting protein, having no cysteine residues, is unable to form either intramolecular or intermolecular disulfide bonds. The secondary and tertiary structures of the purified analog, as determined by circular dichroism and fluorescence spectroscopy, were identical within experimental error to recombinant bovine and human bFGF with unaltered amino acid sequences. Reflecting the similar conformation, the analog protein exhibited mitogenic activity on NIH 3T3 cells which was indistinguishable from the natural sequence molecule.

Spontaneous dissociation-association of monomers of the human-stem-cell-factor dimer.

In its native state, recombinant human-stem-cell-factor (SCF) dimer can spontaneously and rapidly undergo hybridization when two different SCF dimer species are incubated together. SCF species differing in molecular charge, e.g., a wild-type SCF form and a variant with Asp at position 10 instead of Asn, were used in the hybridization studies; the original species and newly formed dimer hybrid can be separated and quantified by cationic-exchange h.p.l.c. The hybridization reaches an equilibrium where the ratio of hybrid dimer to each of the original species is 2. Kinetic studies of the initial rate of hybridization enable a rate constant for monomer dissociation to be determined. This rate constant is influenced by pH, temperature and salt concentration. The pH and salt effects suggest that salt bridges between charged amino acids at the monomer-monomer interface may be present. From the temperature effects, the activation energy for monomer dissociation was determined to be 85.6 kJ/mol, which is typical for oligomeric proteins. Heavily glycosylated recombinant SCF from Chinese-hamster ovary cells exchanged equally well with the bacterially derived non-glycosylated SCF, indicating that the attached carbohydrate moieties had no effect on monomer exchange.

Isolation and characterization of human tissue kallikrein produced in Escherichia coli: biochemical comparison to the enzymatically inactive prokallikrein and methionyl kallikrein.

This report describes bacterial expression, isolation, and characterization of human tissue kallikrein recombinantly produced in Escherichia coli. Successful production of enzymatically active recombinant human kallikrein requires the following processes: expression, solubilization and refolding of prokallikrein, thermolysin activation, and chromatographic separation. All experimental data confirmed that bacterially derived human kallikrein is properly folded and exhibits expected biochemical functions. As confirmed by SDS-PAGE and reverse-phase HPLC, recombinant kallikrein is apparently pure and is devoid of reduced or other partially folded kallikrein forms. Recombinant kallikrein behaves as a monomeric molecule in solution and exhibits full enzymatic activity in hydrolyzing peptide substrates. The molecule can bind to aprotinin to form kallikrein-inhibitor complex at a 1:1 molar ratio. Peptide mapping analysis derived from pepsin digestion of recombinant kallikrein assigned five disulfide bonds which match those of porcine kallikrein predicted from X-ray structure. Peptides containing unpaired cysteines or mispaired disulfide bonds were not detected. Both properly folded prokallikrein and methionyl kallikrein, containing a propeptide and an initiator methionine at their N-termini, respectively, were also produced and isolated. These two molecules are structurally similar to recombinant kallikrein, but are not enzymatically active.

Reversibility of acid denaturation of recombinant interferon-gamma.

It has been shown that interferon-gamma (IFN-gamma) loses activity after acid treatment and this property can be used to distinguish it from other types of interferons. Therefore, reversibility of acid denaturation of IFN-gamma was examined using the recombinant human protein. The fluorescence spectra showed that conformation of the protein is similar before and after acid treatment, suggesting reversibility of the acid denaturation. The antiviral activity of the protein was also identical in the same treatment. However, the antiviral activity was significantly reduced when it was determined by directly diluting the acidic samples into the assay medium containing high salts and serum proteins. Similar results were obtained with the recombinant murine IFN-gamma. This observation demonstrates that acid denaturation of the IFN-gamma is dependent on the way the protein is renatured, and hence that the difference in response to acid treatment between IFN-gamma and other interferons is quantitative rather than qualitative.