Does Near-Infrared Spectroscopy Provide an Early Warning of Low Haematocrit following the Initiation of Hypothermic Cardiopulmonary Bypass in Cardiac Surgery?

This study investigated 151 patients undergoing cardiac surgery to determine whether measurement of regional cerebral oxygen saturation (rScO2) using near-infrared spectroscopy (NIRS) can indicate a low haematocrit after initiation of hypothermic cardiopulmonary bypass (CPB). Haematocrit, rScO2, haemoglobin level, arterial partial pressures of carbon dioxide and oxygen, systemic blood pressure, and nasopharyngeal and rectal temperatures were determined 5 min after the initial administration of heparin for CPB and 90 s after completion of the first cardioplegic solution injection. Immediately after initiation of hypothermic CPB, rScO2, haemoglobin and haematocrit values were significantly lower than those before CPB. No significant correlations were found between the change in haematocrit and changes in left, right and mean rScO2; thus, changes in rScO2 before and after initiation of hypothermic CPB did not reflect changes in haematocrit values. This indicates that NIRS cannot provide early warning of a low haematocrit immediately after initiation of hypothermic CPB in cardiac surgery.

Identification of 11 novel mutations in 49 Korean patients with mucopolysaccharidosis type II

Mucopolysaccharidosis type II (MPS II) or Hunter syndrome is a rare lysosomal storage disorder caused by a deficiency of iduronate-2-sulfatase (IDS). As MPS II is X-linked, patients are usually males with heterogeneous mutations ranging from point mutations to gross deletions and recombination. In 2003, we reported a mutation analysis of 25 patients with MPS II. In this study, 31 mutations in another 49 Korean patients (45 families) with MPS II are reported: 12 missense, nine deletions, four splicing, two nonsense, two insertions, one deletion/insertion, and IDS-IDS2 recombination mutations. Among these mutations, 11 were novel ones (4 missense mutations: Ser61Pro, Pro97Arg, Pro228Ala, and Pro261Ala; 5 deletions: c.344delA, c.420delG, c.768delT, c.1112delC and c.1402delC; 1 deletion/insertion: c.1222delinsTA; and 1 insertion mutation: c.359_360insATCC). The IDS-IDS2 recombination mutations were most frequently observed; all patients with this mutation had the severe MPS II phenotype. However, most of the patients (5/7) with the G374G splicing mutation had an attenuated phenotype, except for two sibling cases with the severe phenotype. Except for a few recurrent mutations such as the G374G, R443X, L522P, and recombination mutations, each patient had a unique individual mutation. Therefore, careful interpretation of genotype-phenotype correlations is warranted.

Pretreatment of rice straw with ammonia and ionic liquid for lignocellulose conversion to fermentable sugars

Pretreatment technology is a prerequisite to facilitate the release of sugars from a lignocellulosic biomass prior to fermentation. Recently, some pretreatment methods have been tried with ionic liquids, but they were still expensive and unpractical. In this study, an efficient pretreatment method using ammonia and ionic liquid was developed for the recovery of bio-digestible cellulose from a lignocellulosic byproduct, rice straw, and the increase of ionic liquid utilization. The combined use of ammonia and ionic liquid ([Emim]Ac) treatment exhibited a synergy effect for rice straw with 82% of the cellulose recovery and 97% of the enzymatic glucose conversion. This cooperative effect showed over 90% of the glucose conversion even with a reduced enzyme usage and incubation time. The ionic liquid was successfully recycled more than 20 times. The 20th-recycled ([Emim]Ac) showed 74% of the cellulose recovery and 78% of the glucose conversion to rice straw. Compared with the conventional pretreatment, our combined method for lignocellulosic biomass pretreatment was an economical and eco-friendly.

Expression of recombinant endochitinase from the Antarctic bacterium, Sanguibacter antarcticus KOPRI 21702 in Pichia pastoris by codon optimization

An endochitinase was previously purified and the gene was cloned from the psychrophilic Antarctic bacterium, Sanguibacter antarcticus (KCTC 13143). In the present study, recombinant endochitinase, rChi21702, was expressed using a yeast expression system (Pichia pastoris) and codon optimization. The expressed rChi21702 was purified by Phenyl-Sepharose column chromatography. Optimal expression yielded 1-mg purified enzyme from 1-L bioreactor culture. When p-NP-(GlcNAc)(2) was used as a substrate, the specific activity of the enzyme was determined to be 20U/mg. In vitro assays and thin-layer chromatography demonstrated that the recombinant enzyme has endochitinase activity that produces diacetyl-chitobiose as a dominant end product when chitooligomers, colloidal chitin, and the chromogenic p-NP-(GlcNAc)(2) are used as substrates. Optimal activity for rChi21702 was observed at 37 degrees C and a pH of 7.6. Interestingly, rChi21702 exhibited 63% of optimal activity at 10 degrees C and 44% activity at 0 degrees C. Taken together, the results indicate that rChi21702 has psychrotolerant endochitinase activity even after recombinant expression in yeast cells.

Hydrogen production of the hyperthermophilic eubacterium, Thermotoga neapolitana under N2 sparging condition

Gas sparging was found to be a useful technique to reduce hydrogen partial pressure in the liquid phase to enhance the hydrogen yields of strictly anaerobically fermentative bacteria. The effect of nitrogen (N(2)) sparging on hydrogen yield was investigated in sterile and non-sterile conditions using a pure strain of the hyperthermophilic eubacteria, Thermotoga neapolitana with glucose or xylose as a carbon source. The maximum hydrogen accumulations reached 41% of the gaseous mixtures after 30-40 h. Two applications of N(2) sparging after the H(2) content in the headspace reached the maximum levels gave an increase of H(2) production by 78% from 1.82 to 3.24 mol H(2)/mol glucose and by 56% from 1.41 to 2.20 mol H(2)/mol xylose. This result suggested that the removal of the produced H(2) from the gas headspace of the limited-volume, closed culture vial when it achieves the maximum level of H(2) tolerance of the bacterium is a necessary technique to improve its H(2) yield.

Detection of pathogen based on the catalytic growth of gold nanocrystals

A homogenous detection of pathogen (Giardia lamblia cysts) based on the catalytic growth of gold nanoparticles (AuNPs) has been studied. In this study, centrifugal filters were employed as tools to concentrate and separate the pathogen cells, and moreover amplify the detection signal. The catalytic growth of gold nanoparticles was verified to be positively related to gold seeds concentration. On this basis, homogenous detection of the pathogenic bacteria in liquid phase was established by means of conjugating antibody to gold seeds. Under the given experimental condition, detection limit of G. lamblia cysts was determined as low as 1.088 x 10(3) cells ml(-1). The additional nonspecific binding tests were also conducted to verify the detection specificity. This sensing platform has been proved to be a sensitive, reliable and simple method for large-scale pathogen detection, and provide valuable insight for the development of gold nanocrystals based colorimetric biosensors.

Simulation on combined rapid gravity filtration and backwash models

Combined rapid gravity filtration and backwash models have been applied to simulate filtration and backwash cycles. The simulated results from the backwash model suggest that an optimum air flow rate exists to maximise particle removal efficiency in the backwash operation for a certain backwash system. The simulation of combined rapid gravity filtration and backwash models suggests that the filter should not be completely cleaned up in the backwash and a certain amount of particles retained on filter grains after backwash can be beneficial for subsequent filtration runs. This is consistent with the experimental results in the literature.

Simulation of combined rapid gravity filtration and backwash models

Combined rapid gravity filtration and backwash models are applied to simulate filtration and backwash cycles. The simulated results from the backwash model suggest that air flow rate can be optimised to maximise particle removal efficiency in the backwash for a particular system. The simulation of combined rapid gravity filtration and backwash models suggests that efficient backwash operation is essential for maintaining the life time of a filter. However, the filter is not advised to be completely cleaned up in the backwash and the particles retained on filter grains after the backwash can be beneficial for subsequent filtration runs.

Selective production of epothilone B by heterologous expression of propionyl-CoA synthetase in Sorangium cellulosum

The metabolic engineering of epothilones, as secondary metabolites, was investigated using Sorangium cellulosum to achieve the selective production of epothilone B, a potent anticancer agent. Thus, the propionyl-CoA synthetase gene (prpE) from Ralstonia solanacearum was heterologously expressed in S. cellulosum to increase the production of epothilone B. Propionyl-CoA synthetase converts propionate into propionyl-CoA, a potent precursor of epothilone B. The recombinant S. cellulosum containing the prpE gene exhibited a significant increase in the resolution of epothilones B/A, with an epothilone B to A ratio of 127 to 1, which was 100 times higher than that of the wild-type cells, demonstrating its potential use for the selective production of epothilone B.

Repeated batch production of epothilone B by immobilized Sorangium cellulosum

Production of extracellular epothilone B, one of the potent anticancer agents, by free and immobilized Sorangium cellulosum was studied using the repeated batch culture process. The concentration of alginate used in immobilization was directly related to the mass transfer rate of nutrients, mechanical stability, and the epothilone B production yield. With the optimized 3% (w/v) calcium alginate carrier, a prolonged repeated batch culture was investigated for the 5 repeated batches for 24 days. The maximum productivity of epothilone B obtained from the alginate-immobilized cells was 5.03 mg/l/day, which is 3 times higher than that of free cells (1.68 mg/l/day).

Monte Carlo simulation of the photon beam characteristics from medical linear accelerators

The MCNPX code has been employed on a personal computer to calculate the dosimetric characteristics of the photon beams from the 6 MV Siemens MX2 and the 10 MV Varian Clinac 2100C linear accelerators. A model of the treatment head includes the major geometric structure within the beam path. The model was used to calculate the energy spectra of the photon beam, percentage depth dose and the dose profiles. The accuracy of the calculated results is examined by comparing them with the measured dose distributions for the two machines. The computed and measured depth dose curves agree to within 2% for all the depths beyond the build-up region for both treatment machines. The calculations agree to within 2% of the measured profiles within the 100-50% dose level. It has been found that the MCNPX code is an effective tool for simulating the clinical photon beam.

Fed-batch cultures of Escherichia coli cells with oxygen-dependent nar promoter systems

The recombinant proteins produced from Escherichia coli as a host cell need to be made at as low a cost as possible because of the end of the monopoly following expiry of the patent on early pharmaceutical proteins, and thus expanding applications to non-pharmaceutical large-scale products. We review in this article how the various promoters used in recombinant E. coli could affect its protein products, especially with emphasis on relatively new oxygen-dependent nar promoters for beta-galactosidase production. Several studies carried out in the authors' laboratory show that the nar promoter does not require any chemicals except 1% nitrate and oxygen for protein production. And according to recent work with the modified strains it is possible to produce the enzyme (beta-galactosidase) even without the nitrate ions at 45% of its total protein content when its cell density reached OD = 176.

The development of fetal surgery

The history of fetal surgery features an absolute dependency upon the possibility of diagnosis before birth. Powerful new imaging methods, the techniques of sampling amniotic fluid and fetal tissue, and modern molecular genetics for the prenatal diagnosis of various congenital diseases have removed the veil of secrecy from the fetus. Even though most prenatally detected congenital malformations can be managed after maternal transport, a few simple anatomic defects require fetal surgery, albeit with predictably poor results. The understanding of intrauterine physiology and pathophysiology in several congenital malformations has been worked out in animal model study, and the natural history of congenital defects revealed by prenatal observations on human fetuses. Selection criteria for intrauterine intervention have been developed. Over the last two decades, surgical techniques for open and endoscopic fetal surgery have been defined and anesthesia and tocolysis for fetal surgery improved. As we enter the 21st century, this field of surgery will surely expand.

The structural and functional organization of the yeast mediator complex

The Mediator complex of Saccharomyces cerevisiae is required for diverse aspects of transcription by RNA polymerase II (pol II). Mediator is composed of two functionally distinct subcomplexes, Rgr1 and Srb4. To identify the structures and functions of each subcomplex, we expressed recombinant proteins for each subunit and assayed their interactions with each other and with basal transcription proteins. The Rgr1 subcomplex is composed of the Gal11 module, which binds activators, and the Med9/10 module. The Med9/10 module is required for both transcriptional activation and repression, and these activities appear to be carried out by two submodules. Proteins in the Med9 submodule interact physically and genetically with Srb10/11, suggesting that the Med9 submodule mediates the repression of pol II. Purified recombinant Srb4 subcomplex stimulated basal transcription of pol II but had little effect on activated transcription and phosphorylation of the C-terminal domain of the Rpb1 subunit of pol II. Both subcomplexes of Mediator interacted with a distinct set of basal transcription factors and pol II. The modular organization of Mediator and the associated functions suggest that the Mediator complex may recruit and/or stabilize the preinitiation complex through several points of contact with transcriptional regulators and basal transcription factors.

Med9/Cse2 and Gal11 modules are required for transcriptional repression of distinct group of genes

The yeast Mediator is composed of two subcomplexes, Rgr1 and Srb4, known to be required for diverse aspects of transcriptional regulation; however, their structural and functional organizations have not yet been deciphered in detail. Biochemical analyses designed to determine the subunit composition of the Rgr1 subcomplex revealed that the regulator-interacting subcomplex has a modular structure and is composed of the Gal11, Med9/Cse2, and Med10/Nut2 modules. Genome-wide gene expression and Northern analyses performed in the presence or absence of the various Mediator modules revealed a distinct requirement for the Gal11, Med9/Cse2, and Med10/Nut2 modules in transcriptional repression as well as activation. GST pull-down analysis revealed that the transcriptional repressor Tup1 binds to distinct but overlapping regions of the Gal11 module that were shown previously to be transcriptional activator binding sites. These data suggest that competition between transcriptional activators and repressors for a common binding site in the Mediator and distinct conformational changes in the Mediator induced by repressor binding may underlie the mechanism of transcriptional repression in eukaryotes.

Biliary atresia associated with meconium peritonitis caused by perforation of small bowel atresia

BACKGROUND/PURPOSE

This report describes our experiences with 5 cases of biliary atresia associated with meconium peritonitis caused by perforation of small bowel atresia.

METHODS

A review of medical records was undertaken in an effort to recognize cases of biliary atresia associated with meconium peritonitis.

RESULTS

Five patients of 171 with biliary atresia (2.9%) were detected to have meconium peritonitis caused by perforation of small bowel atresia. The biliary atresia was not suspected during the initial operation for meconium peritonitis. Total parenteral nutrition (TPN) made it difficult to make an early differential diagnosis of biliary atresia because of the presence of TPN-associated cholestatic jaundice, and the Roux-en-Y limb used for hepatic portoenterostomy could not be made long enough to prevent cholangitis caused by preexisting short bowel. The main complications were severe, intractable cholangitis, short bowel syndrome with malnutrition; TPN-associated liver injury; and wound problems. Two patients died of ascending cholangitis, 1 patient of liver failure that was exacerbated by TPN-associated liver injury, and 1 patient is awaiting a liver transplant. Only 1 patient is in good health, being anicteric and showing normal growth and development.

CONCLUSIONS

Biliary atresia is evidently closely associated with meconium peritonitis caused by perforation of small bowel atresia. The management of these patients is more difficult than that of patients with the usual form of biliary atresia, because of the necessity for a long period of TPN and the combined short bowel syndrome. The ideal management of these conditions has yet to be determined.

Fistula-in-ano in infants: is nonoperative management effective?

PURPOSE

Recently, a number of studies have reported positive results from the nonoperative management of fistula-in-ano in infancy, although it has not been of use in all patients. The purpose of this study was to discern the effective treatment methods of fistula-in-ano in infants.

METHODS

A retrospective review was done of 310 children who required operative management for fistula-in-ano or perianal abscess between January 1991 and July 2000. Eighteen patients displayed an onset of symptoms at less than 1 year of age and a duration of symptoms longer than 12 months. The authors analyzed these patients' medical records.

RESULTS

All patients were boys. The mean duration of the symptoms was 26.6 +/- 27.5 months. Fourteen patients had shown an onset of symptoms at less than 6 months of age. The longest duration was 10 years. The patients showed conservative periods of over 12 months because their parents did not want them to undergo surgery. The disease in these patients followed 2 patterns. One (6 patients) was an onset of symptoms followed by a silent fistula-in-ano state. The other (12 patients) was an onset of symptoms followed by an intermittent relapse of inflammation. All patients underwent fistulotomy, and none of them had recurrent fistula during the follow-up period.

CONCLUSIONS

Although the advantages of a nonoperative management of fistula-in-ano in infants include the avoidance of general anesthesia and surgical intervention, the lesions cannot be cured by a period of conservation. Surgical management is more effective in respect to the time factor.

Molecular cloning and characterization of thermostable DNA ligase from Aquifex pyrophilus, a hyperthermophilic bacterium

A DNA ligase gene from the hyperthermophilic bacterium Aquifex pyrophilus (Ap) was cloned and sequenced. An open reading frame of 2,157 bp that codes for a 82-kDa protein showed 40%-60% homology with a series of NAD+-dependent DNA ligases from different organisms. The recombinant enzyme Ap DNA ligase expressed in Escherichia coli was purified to homogeneity and characterized. The activity of Ap DNA ligase gradually increased in proportion to the concentration of monovalent salt up to 200 mM NaCl, 150 mM KCl, 200 mM NH4Cl, and 350 mM potassium glutamate. The optimum temperature and pH of Ap DNA ligase were greater than 65 degrees C and 8.0-8.6, respectively, for nick-closing activity. More than 75% of the ligation activity was retained after incubation at 95 degrees C for 60 min, whereas the half-lives of Thermus aquaticus and Escherichia coli DNA ligases at 95 degrees C were < or =15 min and 5 min, respectively. Thermostable Ap DNA ligase was applied to repeat expansion detection (RED) and could be a useful enzyme in DNA diagnostics.

Characterization of an oxygen-dependent inducible promoter, the nar promoter of Escherichia coli, to utilize in metabolic engineering

The nar promoters, whose transcription is maximally induced under microaerobic conditions in the presence of nitrate ion, were characterized in fed-batch culture to determine whether they can be used for metabolic engineering, by which overall production of valuable chemicals can be increased. For this purpose, we tested whether the expression level of a reporter gene, the lacZ gene from the nar promoter, could be maintained constant throughout the induction period by manipulation of dissolved oxygen (DO) levels at a given nitrate ion concentration. First, E. coli was grown under aerobic conditions (DO 80%) to absorbance at 600 nm (OD(600)) of 35, then the nar promoter was induced by reduction of DO to different levels, combined with different frequencies and duration of alternating microaerobic and aerobic conditions throughout the entire induction period. For a wild-type nar promoter (pMW61) in a mutant host E. coli with a mutation in the narG gene on the chromosome of the host (RK5265), it was possible to maintain production of beta-galactosidase activity per cell (specific beta-galactosidase activity) at a constant rate at 5000, 10,000, 15,000, and 20,000 Miller units, using different combinations of nitrate ion concentrations (0.1%, 0.5%, and 1%) and DO levels. In addition, it was possible to maintain production of specific beta-galactosidase activity at a constant rate at about 10,000 Miller units in the absence of nitrate ion when a nitrate-independent nar promoter (pMW618) in the narL(-) mutant of the W3110 E. coli strain (W3110narL(-)) was used. Based on these results, we conclude that the nar promoter system provides a convenient expression system for metabolic engineering as well as for maximal production of recombinant proteins under conditions of fed-batch culture.

[Anatomical study and clinical application of medial femoral condylar bone flap pedicled with the saphenous vessels]

OBJECTIVE

To investigate a new operative method for repairing nonunion and defect of tibia.

METHODS

First, observe the relation between the joint branches of descending genicular artery and the saphenous branch of descending genicular artery in 10 cadevers. Then the medial femoral condylar bone flap pedicled with the saphenous vessels was prepared in 4 cadavers for simulated purpose. Clinically, two patients with tibial nonunion were treated by transplantation of this pedicled bone flap.

RESULTS

In the 4 simulated operations, the ink which was injected into the femoral artery could be released from the joint branches. And in the clinical operation, the area of the pedicled bone flaps were 5.0 cm x 2.0 cm x 1.5 cm and 4.5 cm x 1.5 cm x 1.5 cm respectively. Followed up for 8 to 12 weeks, the fracture unioned well.

CONCLUSION

This operation is simple and reliable, it is characterised by 1. unnecessary to anastomosis the vessels 2. reliable blood supply 3. high quality of bone flap 4. either bone flap or bone-skin flap can be chosen 5. long vessel pedicle.