Establishment of immunoglobulin M(IgM)-immunosorbent agglutination assay (ISAGA) for diagnosis of toxoplasmosis

AIM

To establish an immunosorbent agglutination assay (ISAGA) for detection of IgM antibodies against Toxoplasma gondii.

METHODS

In the ISAGA, wells of microtiter plates were coated with anti-human IgM antibodies and sealed with 1% bovine serum albumin. After the test sera were added and incubated, the plates were washed, T. gondii tachyzoite antigen suspension was added, and incubated overnight at 37 degrees C. The ISAGA results were evaluated by comparing with those detected by Danish ISAGA and ELISA and those detected by slide enzyme immunoassay (S-EIA).

RESULTS

Forty-four sera from Danish pregnant women were tested by the IgM-ISAGA, 41(93.2%) were consistent with the Danish results. Sixty-seven sera from Danish and Shanghai pregnant women were detected by IgM-IgM-ISAGA and S-EIA, the total consistency rate was 92.5%. A significant correlation was found between the titers of the ISAGA and S-EIA, with a Pearson correlation coefficient of 0.589(P < 0.001). The titers of ISAGA were eighteen times higher than those of S-EIA. This method enables the detection of IgM antibodies as low as approximately 0.08 IU/ml.

CONCLUSION

The IgM-ISAGA is therefore sensitive, specific, easy to perform, and is useful for mass screening and diagnosing recent Toxoplasma infection or reactivation.

Synthesis and characterization of hydroxyapatite, fluoride-substituted hydroxyapatite and fluorapatite

Powders of hydroxyapatite (HA), partially fluoride-substituted hydroxyapatite (fHA), and fluorapatite (FA) were synthesized in house using optimum methods to achieve relatively pure powders. These powders were assessed by the commonly used bulk techniques of X-ray diffraction (XRD), Fourier transform infra-red (FTIR) and FT-Raman spectroscopies, inductively coupled plasma atomic emission spectroscopy (ICP-AES), and F-selective electrode. In addition, the current study has employed transmission electron microscopy (TEM), involving morphological observation, electron diffraction and energy-dispersive X-ray spectrometry (EDX), as an effective analytical technique to evaluate the powders at a microscopic level. The HA and fHA particles were elongated platelets about 20 x 60 nm in size, while FA particles were over twice this size. Calcination of the HA and fHA powders at 1000 degrees C for 1 h resulted in increased grain size and crystallinity. The calcined fHA material appeared to possess a crystal structure intermediate between HA and FA, as evidenced by the (3 0 0) peak shift in XRD, as well as by the position of the hydroxyl bands in the FTIR spectra. This result was consistent with electron diffraction of individual particles. Small levels of impurities in some of the powders were identified by EDX and electron diffraction, and the carbonate content was detected by FTIR. The use of TEM in conjunction with the bulk techniques has allowed a more thorough assessment of the apatites, and has enabled the constituents in these closely related apatite powders to be identified.

OxLDL upregulates growth-regulation oncogene alpha expression in human endothelial cells

OBJECTIVE

To explore the effect of oxLDL on CXC chemokine growth-regulated oncogene alpha (GRO alpha) expression in human endothelial cells and the possible functional significance of the effect.

METHODS

LDL was isolated by sequential ultracentrifugation and oxidized to oxLDL. Reverse transcription-polymerase chain reaction with GAPDH as internal standard was applied and CXC chemokine GRO alpha mRNA in endothelial ECV304 cells was examined. ELISA was used to determine GRO alpha protein expression on ECV304 cells surface and in the medium. With static cell adhesion assays, the physiological significance of elevated GRO alpha expression was tested.

RESULTS

OxLDL, not LDL, treatment of ECV304 cells significantly induced the expression of GRO alpha mRNA that was not detectable in untreated cells. Induction of expression was first evident at 1 h, became maximal at 2 h, and was substantially decreased by 4 h. In a concentration- and time-dependent manner, oxLDL, and not LDL, induced a significant upregulation of GRO alpha surface expression in ECV304 cells that was at a barely detectable level in unstimulated ECV304 cells. GRO alpha protein in the medium did not change significantly. Exposure of ECV304 cells to 40 micrograms protein/ml oxLDL for 24 h resulted in a marked increase in the number of U937 cells bound to ECV304 cells and antibodies to GRO alpha inhibited adhesion.

CONCLUSION

OxLDL functionally upregulated GRO alpha expression in endothelial cells.

[Study on high-efficiency gene transfer of pseudotyped HIV vector]

OBJECTIVE

To investigate the high-efficiency of pseudotyped HIV as gene transfer vector.

METHODS

Three plasmids of pseudotyped HIV gene transfer vector system were transferred into packaging cell line 293T by Ca3 (PO4)2 precipitation method. GFP (Green Fluorescence Protein) or HSV-tk gene was constructed in the plasmid pHR'CS respectively (pHR'CS.GFP or pHR'CS.HSV-tk). The pseudotyped HIV particles were observed through electronic microscopy and were measured through spectrofluorophotometer. High titer pseudotyped HIV was harvested from volume of virus-producing cell supernatant and concentrated. Ovarian epithelial cancer cell line SKOV3 and normal human gingival fibroblast cell GF were infected by pseudotyped HIV. PCR and RT-PCR were resorted to demonstrate the successful transduction and transcription of the HSV-tk gene. After administration of GCV, the changes of those cells and apoptosis were observed through optical microscopy. The cytotoxicity efficacy of HSV-tk/GCV system was evaluated by MTT method. The growth inhibition rate (GIR) of cells and inhibition concentration 50 (IC50) were counted.

RESULTS

The above plasmids were effectively transferred into 293T cell. A lot of pseudotyped HIV particles were observed through electronic microscopy. The virus supernatant had a high absorbing value at 510 nm through spectrofluorophotometer, which proved the existence of virus. After pseudotyped HIV infection, SKOV3 and GF had remarkable infection rate. 600 bp strand was seen through PCR and RT-PCR. Changes and apoptosis of cells followed by administration of GCV were observed. The MTT method showed that the cytotoxicity efficacy of GCV was high to SKOV3 and GF cell.

CONCLUSIONS

The pseudotyped HIV is a high-efficiency gene transfer vector.

Investigation of the role of the domain linkers in separate site catalysis by Clostridium symbiosum pyruvate phosphate dikinase

Pyruvate phosphate dikinase (PPDK) catalyzes the reversible reaction: ATP + P(i) + pyruvate <--> AMP + PP(i) + PEP using Mg2+ and NH4+ ions as cofactors. The reaction takes place in three steps, each mediated by a carrier histidine residue located on the surface of the central domain of this three-domain enzyme: (1) E-His + ATP <--> E-His-PP.AMP, (2) E-His-PP.AMP + P(i) <--> E-His-P + AMP + PP(i), (3) E-His-P + pyruvate <--> E-His + PEP. The first two partial reactions are catalyzed at an active site located on the N-terminal domain, and the third partial reaction is catalyzed at an active site located on the C-terminal domain. For catalytic turnover, the central domain travels from one terminal domain to the other. The goal of this work is to determine whether the two connecting linkers direct the movement of the central domain between active sites during catalytic turnover. The X-ray crystal structure of the enzyme suggests interaction between the two linkers that may result in their coordinated movement. Mutations were made at the linkers for the purpose of disrupting the linker-linker interaction and, hence, synchronized linker movement. Five linker mutants were analyzed. Two of these contain 4-Ala insertions within the solvated region of the linker, and three have 3-residue deletions in this region. The efficiencies of the mutants for catalysis of the complete reaction as well as the E-His + ATP <--> E-His-PP.AMP partial reaction at the N-terminal domain and the E-His + PEP <--> E-His-P + pyruvate reaction at the C-terminal domain were measured to assess linker function. Three linker mutants are highly active catalysts at both active sites, and the fourth is highly active at one site but not the other. These results are interpreted as evidence against coordinated linker movement, and suggest instead that the linkers move independently as the central domain travels between active sites. It is hypothesized that while the linkers play a passive role in central domain-terminal domain docking, their structural design minimizes the conformational space searched in the diffusion process.

Effects of spectator ligands on the specific recognition of intrastrand platinum-DNA cross-links by high mobility group box and TATA-binding proteins

The results presented describe the effects of various spectator ligands, attached to a platinum 1,2-intrastand d(GpG) cross-link in duplex DNA, on the binding of high mobility group box (HMGB) domains and the TATA-binding protein (TBP). In addition to cisplatin-modified DNA, 15-base pair DNA probes modified by [Pt(1R,2R-diaminocyclohexane)](2+), cis-[Pt(NH(3))(cyclohexylamine)](2+), [Pt(ethylenediamine)](2+), cis-[Pt(NH(3))(cyclobutylamine)](2+), and cis-[Pt(NH(3))(2-picoline)](2+) were examined. Electrophoretic mobility shift assays show that both the A and B domains of HMGB1 as well as TBP discriminate between different platinum-DNA adducts. HMGB1 domain A is the most sensitive to the nature of the spectator ligands on platinum. The effect of the spectator ligands on protein binding also depends highly on the base pairs flanking the platinated d(GpG) site. Double-stranded oligonucleotides containing the AG*G*C sequence, where the asterisks denote the sites of platination, with different spectator ligands are only moderately discriminated by the HMGB proteins and TBP, but the recognition of dsTG*G*A is highly dependent on the ligands. The effects of HMGB1 overexpression in a BG-1 ovarian cancer cell line, induced by steroid hormones, on the sensitivity of cells treated with [Pt(1R,2R-diaminocyclohexane)Cl(2)] and cis-[Pt(NH(3))(cyclohexylamine)Cl(2)] were also examined. The results suggest that HMGB1 protein levels influence the cellular processing of cis-[Pt(NH(3))- (cyclohexylamine)](2+), but not [Pt((1R,2R)-diaminocyclohexane)](2+), DNA lesions. This result is consistent with the observed binding of HMGB1a to platinum-modified dsTG*G*A probes but not with the binding affinity of HMGB1a and HMGB1 to platinum-damaged dsAG*G*C oligonucleotides. These experiments reinforce the importance of sequence context in platinum-DNA lesion recognition by cellular proteins.

Investigation of the catalytic site within the ATP-grasp domain of Clostridium symbiosum pyruvate phosphate dikinase

Pyruvate phosphate dikinase (PPDK) catalyzes the interconversion of ATP, P(i), and pyruvate with AMP, PP(i), and phosphoenolpyruvate (PEP) in three partial reactions as follows: 1) E-His + ATP --> E-His-PP.AMP; 2) E-His-PP.AMP + P(i) --> E-His-P.AMP.PP(i); and 3) E-His-P + pyruvate --> E.PEP using His-455 as the carrier of the transferred phosphoryl groups. The crystal structure of the Clostridium symbiosum PPDK (in the unbound state) reveals a three-domain structure consisting of consecutive N-terminal, central His-455, and C-terminal domains. The N-terminal and central His-455 domains catalyze partial reactions 1 and 2, whereas the C-terminal and central His-455 domains catalyze partial reaction 3. Attempts to obtain a crystal structure of the enzyme with substrate ligands bound at the nucleotide binding domain have been unsuccessful. The object of the present study is to demonstrate Mg(II) activation of catalysis at the ATP/P(i) active site, to identify the residues at the ATP/P(i) active site that contribute to catalysis, and to identify roles for these residues based on their positions within the active site scaffold. First, Mg(II) activation studies of catalysis of E + ATP + P(i) --> E-P + AMP + PP(i) partial reaction were carried out using a truncation mutant (Tem533) in which the C-terminal domain is absent. The kinetics show that a minimum of 2 Mg(II) per active site is required for the reaction. The active site residues used for substrate/cofactor binding/activation were identified by site-directed mutagenesis. Lys-22, Arg-92, Asp-321, Glu-323, and Gln-335 mutants were found to be inactive; Arg-337, Glu-279, Asp-280, and Arg-135 mutants were partially active; and Thr-253 and Gln-240 mutants were almost fully active. The participation of the nucleotide ribose 2'-OH and alpha-P in enzyme binding is indicated by the loss of productive binding seen with substrate analogs modified at these positions. The ATP, P(i), and Mg(II) ions were docked into the PPDK N-terminal domain crevice, in an orientation consistent with substrate/cofactor binding modes observed for other members of the ATP-Grasp fold enzyme superfamily and consistent with the structure-function data. On the basis of this docking model, the ATP polyphosphate moiety is oriented/activated for pyrophosphoryl transfer through interaction with Lys-22 (gamma-P), Arg-92 (alpha-P), and the Gly-101 to Met-103 loop (gamma-P) as well as with the Mg(II) cofactors. The P(i) is oriented/activated for partial reaction 2 through interaction with Arg-337 and a Mg(II) cofactor. The Mg(II) ions are bound through interaction with Asp-321, Glu-323, and Gln-335 and substrate. Residues Glu-279, Asp-280, and Arg-135 are suggested to function in the closure of an active site loop, over the nucleotide ribose-binding site.

Vestibular discrimination of gravity and translational acceleration

According to Einstein's equivalence principle, linear accelerations experienced during translational motion are physically indistinguishable from changes in orientation relative to gravity experienced during tilting movements. Nevertheless, despite these ambiguous sensory cues provided by the primary otolith afferents, perceptual and motor responses discriminate between gravity and translational acceleration. There is growing evidence to suggest that the brain resolves this ambiguity primarily by combining signals from multiple sensors, the semicircular canals being a main extra otolith contributor. Here, we summarize the experimental evidence in support of the canal influences on the neural processing of otolith cues, provide specific experimental results in rhesus monkeys, and discuss and compare previously proposed models that combine otolith and semicircular-canal signals in order to provide neural estimates of gravity and linear acceleration.

LF15-0195 prevents the induction and inhibits the progression of rat anti-GBM disease

BACKGROUND

LF15-0195 is a novel immunosuppressant that is currently in phase II clinical trials for the treatment of vasculitis. This study examined whether LF15-0195 could suppress the induction and progression of rat anti-glomerular basement membrane (anti-GBM) glomerulonephritis.

METHODS

Rapidly progressive glomerulonephritis was induced in primed rats by the administration of anti-GBM serum. In the first experiment, LF15-0195 was given daily by subcutaneous injection (days 0 to 14) to treat the induction of anti-GBM disease analyzed at day 14. In a second experiment, rats received LF15-0195 as an intervention treatment from days 7 to 28 (continuous therapy) or days 7 to 12 (pulse therapy) to treat the progression of disease assessed at day 28.

RESULTS

Continuous LF15-0195 treatment during the induction of anti-GBM disease (experiment 1) prevented proteinuria and loss of renal function, and markedly reduced histological kidney lesions and renal fibrosis. LF15-0195 also reduced kidney leukocyte infiltrate, urine excretion of interleukin-1beta (IL-1beta) and transforming growth factor-beta (TGF-beta), and the serum antibody response, but not kidney deposition of Ig and C3. When LF15-0195 treatment was initiated at day 7, both continuous and pulse therapy partially inhibited disease progression by suppressing the loss of renal function, interstitial macrophage and T-cell accumulation, tubular cell proliferation, and renal fibrosis.

CONCLUSION

LF15-0195 prevents the induction and suppresses the progression of rat anti-GBM disease through multiple mechanisms of action, suggesting that this drug may have significant therapeutic potential in human glomerulonephritis. The similar efficacy of continuous and pulse intervention treatment in this model indicates that short-term LF15-0195 treatment may achieve optimal benefit without prolonged bone marrow suppression.

Cytokine responses and myocardial injury in coronary artery bypass grafting

OBJECTIVE

Cardiopulmonary bypass is acknowledged to be one of the major causes of a complex systemic inflammatory response after cardiac surgery, and it may contribute to postoperative complications and even multiple organ dysfunction. We here compared the cytokine responses and the degree of myocardial injury after coronary artery bypass grafting with or without cardiopulmonary bypass.

METHODS

Nine patients underwent off-pump revascularization and 13 with cardiopulmonary bypass. Plasma levels of tumor necrosis factor-alpha (TNF-alpha), interleukin (IL)-6, IL-8 and IL-10 were measured before anesthesia induction, and 5 min, 1, 4, and 20 h after reperfusion to the myocardium. Levels of the MB isoenzyme of creatine kinase (CK-MB) were also measured after the operation.

RESULTS

Levels of TNF-alpha were low in both groups. A delayed elevation of IL-6 was noted in the off-pump group. IL-8 and IL-10 levels were significantly higher in the CPB than in the off-pump patients after reperfusion (p=0.006 and 0.001 respectively). Postoperative CK-MB levels were significantly higher in the CPB than in the off-pump group (p=0.001). Cytokine levels correlated with CK-MB values.

CONCLUSION

The results indicated that off-pump revascularization was associated with reduced cytokine responses and less severe myocardial injury. The degree of myocardial injury, as defined by CK-MB release, correlated with cytokine release. Intervention designed to reduce cytokine responses in cardiac surgery may be advantageous for patients with severe comorbidity.

Cardioprotective effect of adenosine pretreatment in coronary artery bypass grafting

OBJECTIVE

There are several reports of the use of adenosine as a cardioprotective agent during cardiac surgery. Adenosine treatment might affect neutrophils and inflammatory mediators. The present prospective randomized study was designed to investigate the effect of adenosine pretreatment on myocardial recovery and inflammatory response in patients undergoing elective coronary artery bypass surgery.

DESIGN

A prospective, randomized, controlled study.

SETTING

Operative unit and ICU in a university hospital in Finland.

PATIENTS

Thirty male patients undergoing primary, elective coronary revascularization.

INTERVENTIONS

Patients in the adenosine group received a 7-min infusion of adenosine (total, 650 microg/kg) before the initiation of cardiopulmonary bypass.

MEASUREMENTS

Postoperative creatine kinase (CK)-MB release and hemodynamics were recorded. Perioperative leukocyte and cytokine release were measured.

RESULTS

Adenosine pretreatment resulted in less CK-MB release and an improved postbypass cardiac index. Similar leukocyte counts and cytokine responses were seen in both groups perioperatively. Neutrophil counts were similar between the groups before and after myocardial ischemia when measured simultaneously in arterial and coronary sinus blood.

CONCLUSIONS

The present results support the hypothesis that adenosine pretreatment is cardioprotective in humans, but the present dose failed to regulate the inflammatory responses after coronary artery bypass grafting.

[Experimental study on effect of bushen huoxue xiezhuo decoction in treating minimal change nephropathy]

OBJECTIVE

To explore the therapeutic effect and mechanism of Bushen Huoxue Xiezhuo Decoction (BHXD) in treating minimal change nephropathy (MCN) in rats.

METHODS

The MCN model rats established by a single intravenous injection of Adriamycin were divided into the model, BHXD group, and a normal group was set up for control. The effect of treatment on renal function, hemorrheologic parameters, renal tissue TGF-beta 1 expression and polyanion sites on glomerular basement membrane were observed dynamically.

RESULTS

After treatment, all the parameters between the BHXD group and the model group were significantly different respectively, morphological observation also showed the pathological changes in the BHXD group were milder than those in the model group.

CONCLUSION

BHXD treatment could markedly improve the renal function, alleviate blood hypercoagulability and hyperviscosity, protect the anion barrier and delay the progression of glomerular fibrosis and sclerosis.

Inflammatory cytokines and soluble receptors after coronary artery bypass grafting

Much interest has been focused on the overexpression of proinflammatory cytokines, but studies on their soluble receptors are rare. For a comprehensive picture of cytokine activation in cardiac surgery, a combination of cytokines and the corresponding soluble receptor concentration should be determined. Blood samples were collected from the radial artery and coronary sinus perioperatively in ten patients undergoing coronary artery bypass grafting with cardiopulmonary bypass. TNF-alpha, IL-6, sTNFRI, sTNFRII, and sIL-6R levels in the plasma were determined. Systemic TNFRI, TNFRII and IL-6 increased significantly after reperfusion to the myocardium, while perioperative systemic sIL-6r levels were similar. Arterial and sinus levels of TNFRI, TNFRII and sIL-6r were similar before cardiopulmonary bypass. Five minutes after reperfusion to the myocardium, higher sinus TNFRI and TNFRII and lower sinus sIL-6R levels were observed as compared to the arterial levels. The myocardium release of sTNFRI (r=0.57, P=0.089) and sTNFRII (r=0.64, P=0.047) positively correlated with the change of cardiac index after cardiopulmonary bypass. Myocardium releases sTNFRI and sTNFRII after ischaemic-reperfusion injury, and this may be of benefit to cardiac performance. sIL-6R is constantly being produced in areas other than the myocardium, while sIL-6R levels are reduced by consumption in the myocardium after ischaemic-reperfusion injury.

Anti-inflammatory effects of 17beta-estradiol pretreatment in men after coronary artery surgery

OBJECTIVE

To investigate the anti-inflammatory and hemodynamic effects of 17beta-estradiol in men undergoing elective coronary artery bypass graft surgery (CABG).

DESIGN

Prospective, randomized, controlled.

SETTING

Operating room and intensive care unit in a university hospital.

PARTICIPANTS

Twenty-one men undergoing primary, elective CABG surgery.

INTERVENTION

17beta-estradiol, 2mg, was given orally twice in 14 hours before the operation.

MEASUREMENTS AND MAIN RESULTS

Leukocyte counts, plasma myeloperoxidase, tumor necrosis factor-alpha, interleukin (IL)-6, IL-8, and IL-10 were measured perioperatively. Leukocyte counts were lower in the 17beta-estradiol group than in controls at 6 hours (11.4 +/- 2.0 hours v 15.5 +/- 4.7 hours x 10(9)/L) and 20 hours (11.6 +/- 1.9 hours v 13.6 +/- 2.5 hours x 10(9)/L) after reperfusion (p = 0.03). The release of myeloperoxidase was lower in the 17beta-estradiol group than in controls (5 minutes; 634.4 +/- 213.1 microg/mL v 773.1 +/- 209.3 microg/mL; 4 hours, 305.0 +/- 108.0 microg/mL v 441.3 +/- 191.6 microg/mL; p = 0.02). Systemic vascular resistance index was lower just after cardiopulmonary bypass, and cardiac index was higher postoperatively in the 17beta-estradiol group as compared with controls.

CONCLUSION

Pretreatment with 17beta-estradiol can limit leukocyte activation in men after CABG surgery.

Possible prevention by abieslactone of development of diethylnitrosamine-initiated GST-P positive foci in the rat liver

Triterpenoid compounds, isolated from plants of Abies genus (Pinceae), are known to exert anti-tumor promotion activities in mouse skin carcinogenesis. In the present study, we investigated whether AVB-1 and acid and acid methyl ester derivatives have inhibitory effects on rat hepatocarcinogenesis by using a liver medium-term bioassay for carcinogens (Ito's test), immunohistochemically assessing the numbers and areas per cm(2) of preneoplastic lesions, glutathione S-transferase placental form (GST-P)-positive foci. In experiment 1, 6-week-old male Fisher 344 rats were given a single intraperitoneal injection of diethylnitrosamine (200 mg/kg b.w.) and subjected to two-thirds partial hepatectomy at week 3. From weeks 2 to 8, the compounds were given three times a week at a dose of 1 mg/kg b.w. by i.g. gavage and found to significantly decrease the number of GST-P-positive foci in the liver. In experiment 2, AVB-1 was given three times a week at doses of 3, 1, or 0.3 mg/kg b.w. by i.g. gavage from weeks 2 to 8. All doses of AVB-1 significantly decreased the numbers of GST-P-positive foci. Thus, our results suggest that AVB-1 is a chemopreventive agent for rat hepatocarcinogenesis.

Autoxidation of substituted phenols catalyzed by cobalt Schiff base complexes in supercritical carbon dioxide

This first study of O(2) oxidation (autoxidation) of substituted phenols catalyzed by a dioxygen carrier in supercritical carbon dioxide (scCO(2)) provides additional insights into the established mechanism of reactions that have been much studied in conventional solvents. As has been long believed, the cobalt(II) dioxygen carriers of the class represented by [[N,N'-bis(3,5-di-tert-butylsalicylidene)-1,2-cyclohexanediaminato(2-)]cobalt(II)], Co(salen), show both oxidase and oxygenase activities during oxygenation of substituted phenols in scCO(2). The catalytic autoxidation of 2,6-di-tert-butylphenol (DTBP) and 3,5-di-tert-butylphenol (35-DTBP) in scCO(2) was studied by analysis of products in batch reactions with carefully controlled variables, in the presence of a large excess of O(2), at 207 bar of total pressure and a reaction temperature of 70 degrees C. The oxidation of 35-DTBP yielded only traces of products under the same experimental conditions that converted DTBP totally to a mixture of the oxygenation product 2,6-di-tert-butyl-1,4-benzoquinone (DTBQ) and the related product of radical coupling 3,5,3',5'-tetra-tert-butyl-4,4'-diphenoquinone (TTDBQ). The effects on conversion of DTBP to products and on selectivity between the two products were studied for variations in temperature and the concentrations of catalyst, oxygen, and methylimidazole. Selectivity in favor of the O-transfer product DTBQ over the self-coupling of the phenoxy radical was observed upon changing the oxygen concentration. In contrast, selectivity remained unaffected over a wide range of temperatures and catalyst concentrations. The oxygen dependence of both the conversion and selectivity showed saturation effects identifying the dioxygen complex as the effective oxidant in both the initial radical formation step and the oxygenation of that radical. No direct reaction is observed between the electrophilic phenoxy radical and O(2).

Epigenetic heterogeneity at imprinted loci in normal populations

Genomic imprinting is the phenomenon by which the two alleles of certain genes are differentially expressed according to their parental origin. Extensive analysis of allelic expression at multiple imprinted loci in a normal population has not performed so far. In the present study, we examined the allelic expression pattern of three imprinted genes in a panel of 262 Japanese normal individuals. We observed differences in the extent of maintenance of allele-specific expression of the three genes. The allelic expression of small nuclear ribonucleoprotein N (SNRPN) was stringently regulated while that of multimembrane-spanning polyspecific transporter-like gene 1 (IMPT1) showed a large degree of variation. Significant biallelic expression of insulin-like growth factor II (IGF2) was observed in about 10% of normal individuals. Our findings add to the accumulating evidence for variable allelic expression at multiple loci in a normal human population. This epigenetic heterogeneity can be a stable trait and potentially influence individual phenotypes.

[Subtotal laryngectomy reconstructed by platysma myocutaneous flaps]

OBJECTIVE

To study the feasibility, surgical techniques and the results of laryngeal function preservation during subtotal laryngectomy in laryngeal carcinoma.

METHODS

A retrospective review was made of 13 patients treated by subtotal laryngectomy and laryngeal reconstruction from 1991 to 1996. Eleven patients were male and 2 were female. The age ranged from 46 to 72 years, with a mean of 53.25. All cases were of stage IV. The essence of this operation is to reconstruct the new larynx with two platysma myocutaneous flaps following subtotal laryngectomy.

RESULTS

The success rate of voice rehabilitation was 100%. Among them, the acceptability rating scores in 11 cases were 7 and the intelligibility scores ranged from 95% to 98%. The other two cases had acceptability 5 and intelligibility form 90% to 94%. The three-year survival rate was 84.6% (11/13), 5-year survival rate was 76.9% (10/13).

CONCLUSION

This form of laryngeal reconstruction in subtotal laryngectomy is helpful to restore laryngeal function and decrease the rate of total laryngectomy. The procedure is easy, safe and applicable to patients treated by subtotal laryngectomy.

Cross-axis adaptation of the translational vestibulo-ocular reflex

The adaptive plasticity of the translational vestibulo-ocular reflex (VOR) was investigated in rhesus monkeys after 2-h exposure to either vertical or torsional optic flow stimulation accompanied by lateral translation stimuli (0.5 Hz). Because of the inherent ambiguity in the otolith system for the detection of gravitoinertial accelerations, we hypothesized that cross-axis adaptation of the translational VOR during lateral motion would be preferentially selective for a torsional optic flow stimulus that would mimic a roll tilt movement. However, we found that both vertical and torsional adaptation was possible. Furthermore, there was no significant preference for whether the torsional adaptation was in phase or out of phase with the apparent tilt induced by the motion stimulus. These results suggest that, at least at 0.5 Hz, there seems to be no preferential, visually induced adaptive capacity of the otolith system for tilt/translation reinterpretation during motion. Like the rotational VOR, translational VOR appears to exhibit a general form of cross-axis adaptation that operates for different directions of optic flow stimulation.

Cephalometric image analysis and measurement for orthognathic surgery

Automatic identification of landmarks in cephalometry is very important and useful for orthognathic surgery. A computerised automatic cephalometric analysis system (CACAS), based on image processing, is presented. For an original X-ray image, median filtering and histogram equalisation are used to improve image quality. The edge of an X-ray image is detected by a wavelet transform and Canny filter. Seventeen landmarks in cephalometry are successfully identified by knowledge-based edge tracing and changeable templates. Seventy-three measurements based on distances, angles and ratios between landmarks are computed automatically. The reliability of the landmarks and the validity of the measurements are compared for automatic and manual operation. The values of measurements obtained by CACAS are more precise and reliable: the mean error for linear measurements is less than 0.9mm; the mean error for angular measurements is less than 1.2 degrees. The rate of validity is over 80%, even if the image quality is poor. For an image with a high signal-to-noise ratio, the rate of validity of landmarking and measurements using the CACAS system is over 90%.