A novel 2-aminomuconate deaminase in the nitrobenzene degradation pathway of Pseudomonas pseudoalcaligenes JS45

2-Aminomuconate, an intermediate in the metabolism of tryptophan in mammals, is also an intermediate in the biodegradation of nitrobenzene by Pseudomonas pseudoalcaligenes JS45. Strain JS45 hydrolyzes 2-aminomuconate to 4-oxalocrotonic acid, with the release of ammonia, which serves as the nitrogen source for growth of the microorganism. As an initial step in studying the novel deamination mechanism, we report here the purification and some properties of 2-aminomuconate deaminase. The purified enzyme migrates as a single band with a molecular mass of 16.6 kDa in 15% polyacrylamide gel electrophoresis under denaturing conditions. The estimated molecular mass of the native enzyme was 100 kDa by gel filtration and 4 to 20% gradient nondenaturing polyacrylamide gel electrophoresis, suggesting that the enzyme consists of six identical subunits. The enzyme was stable at room temperature and exhibited optimal activity at pH 6.6. The Km for 2-aminomuconate was approximately 67 microM, and the Vmax was 125 micromol x min(-1) x mg(-1). The N-terminal amino acid sequence of the enzyme did not show any significant similarity to any sequence in the databases. The purified enzyme converted 2-aminomuconate directly to 4-oxalocrotonate, rather than 2-hydroxymuconate, which suggests that the deamination was carried out via an imine intermediate.

Prediction of the secondary structure contents of globular proteins based on three structural classes

The prediction of the secondary structural contents (those of alpha-helix and beta-strand) of a globular protein is of great use in the prediction of protein structure. In this paper, a new prediction algorithm has been proposed based on Chou's database [Chou (1995), Proteins 21, 319-344]. The new algorithm is an improved multiple linear regression method, taking into account the nonlinear and coupling terms of the frequencies of different amino acids and the length of the protein. The prediction is also based on the structural classes of proteins, but instead of four classes, only three classes are considered, the alpha class, beta class, and the mixed alpha+beta and alpha/beta class or simply the alphabeta class. Thus the ambiguity that usually occurs between alpha+beta proteins and alpha/beta proteins is eliminated. A resubstitution examination for the algorithm shows that the average absolute errors are 0.040 and 0.035 for the prediction of alpha-helix content and beta-strand content, respectively. An examination of cross-validation, the jackknife analysis, shows that the average absolute errors are 0.051 and 0.045 for the prediction of alpha-helix content and beta-strand content, respectively. Both examinations indicate the self-consistency and the extrapolating effectiveness of the new algorithm. Compared with other methods, ours has the merits of simplicity and convenience for use, as well as high prediction accuracy. By incorporating the prediction of the structural classes, the only input of our method is the amino acid composition and the length of the protein to be predicted.

[A clinical analysis of 64 cases of pemphigus]

OBJECTIVE

Reasonable therapeutic dosage regimen for pemphigus are analyzed to find the factors related to prognosis.

METHODS

A retrospective study is made on 64 cases of pemphigus who were admitted to our hospital between 1986-1996.

RESULTS

Sixty-two of 64 cases with pemphigus were treated with systemic administration of corticosteroids. The average dosage of prednisone for controlling the diseases were 0.958 mg.kg-1.d-1 for mild-type of pemphigus (12 cases) and 1.145 mg.kg-1.d-1 for severe-type (50 cases) respectively. Furthermore, 26 of 62 cases were treated with corticosteroids only, and the average dosage of prednisone for controlling the diseases was 1.072 mg.kg-1.d-1 while in 36 cases treated with corticosteroids combined with immunosuppressors, the average dosage of prednisone was 1.178 mg.kg-1.d-1. The rate of side-effects and complications were 15.4% in patients with corticosteroids alone and 36.1% in patients with combined therapy. Six of eight patients who died were diagnosed pemphigus vulgaris and seven with a course of disease less than 3 years.

CONCLUSIONS

We recommend a moderate to high dosage of corticosteroids be the first choice to control pemphigus. Those who were effective with steroids are not recommended to use additional immunosuppressors. Patients with pemphigus vulgaris usually have a poor prognosis while those who could survived more than 4 years usually have a better outcome.

[The timing and mode of surgery in patients with severe acute pancreatitis]

OBJECTIVE

To investigate the timing and mode of surgical management in patients with severe acute pancreatitis (SAP).

METHOD

The timing, mode of operation and mortality were reviewed retrospectively in 50 SAP cases undergoing laparotomy in our hospital from 1985 to 1994.

RESULT

The overall mortality was 14% and 85.7% of the mortality falls on the age between 40 to 60 years, with no difference in etiology and sex. The operative mortality reduced gradually in patients with longer duration of illness (P > 0.05). The operative mortality of 31.8% in patients undergoing laparotomy within 12 h after hospitalization was significantly higher (P < 0.05) than in these operated on later. When the number of injured extra-pancreatic organs increased, the mortality also increased significantly (chi(2) = 5.99, P < 0.05). The related mortality with shock, pancreatic necrosis and multiorgan failure (MOF) was 31.8%, 31.6% and 28%, respectively (P < 0.05). The main procedures of surgical management were pancreatic debridement and/or drainage, and combined surgical measures.

CONCLUSION

The laparotomy timing is an important factor influencing mortality as well as the severity of pancreatic necrosis, sepsis, and MOF. Delayed laparotomy and 24 h preoperative management is recommended. Surgery adopted should be simple, efficient in drainage and debridement.

Differential involvement of opioid receptors in intrathecal butorphanol-induced analgesia: compared to morphine

The present experiments were performed to investigate the differential involvement of the opioid receptor subtypes in the antinociception of intrathecal (IT) butorphanol compared to IT morphine. A single dose (26 nmol) of IT nor-binaltorphimine (nor-BNI), beta-funaltrexamine (beta-FNA), and naltrindole (NTI) demonstrated a significant attenuation in the overall antinociception of IT butorphanol (52 nmol) or IT morphine (26 nmol). However, IT butorphanol elicits thermal antinociceptive effect through kappa > delta > or = mu, whereas morphine acts on mu >delta >> kappa. These results indicate that the antinociceptive effect of both IT butorphanol and IT morphine are mediated through mu, delta, and kappa opioid receptors in different relative orders.

[The changes of erythrocyte deformability and cardial function in coronary heart disease with various degrees of coronary stenosis]

According to the extent of coronary maximal stenosis, 29 cases of coronary heart disease (CHD) were classified into two groups: (I) obvious stenosis (OS, narrowing > or = 50% in luminal diameter, n = 15); (II) mild stenosis (MS, marrowing < 50% in luminal diameter, n = 14). The results showed that erythrocyte deformability index (DI), left ventricular ejection fraction (EF%) and fractional shortening (FS%) in the CHD patients were decreased as compared with those in the control group (P < 0.05 or 0.01), and the DI, EF and FS in the OS group were significantly lower than those in the MS group (P < 0.05). These suggest that DI, EF and FS may be of predictable value in identifying CHD patients with or without significant coronary stenosis.

[Short-and long-term therapeutic effects of brachytherapy on intracavitary residual tumor in 563 nasopharyngeal carcinoma (NPC) patients]

OBJECTIVE

To evaluates the effect of brachytherapy on intracavitary residual tumor in patients with NPC after external radiation therapy.

METHODS

Five hundred fifty three NPC patients with residual tumor in the nasopharynx were treated with large dose brachytherapy (20-25 Gy). The treatment results were retrospectively evaluated.

RESULTS

Within 3 months after brachytherapy, the overall regression rate of the residual tumor was 90.4%. Upon long-term follow-up, the 1-, 3-, and 5-year survival rate was 89.6%, 67.0% and 55.4%, respectively. The major complications of the after-loading treatment were nasal obstruction (16.2%), necrosis of the naso-pharynx (0.9%) and perforation of soft palate in 2 patients.

CONCLUSION

Brachytherapy is effective in the treatment of residual NPC especially in patients in early stage. It may not be helpful for stage IV patients.

Amino acid residues in both the protein splicing and endonuclease domains of the PI-SceI intein mediate DNA binding

A structure-based model describing the interaction of the two-domain PI-SceI endonuclease with its 31-base pair DNA substrate suggests that the endonuclease domain (domain II) contacts the cleavage site region of the substrate, while the protein splicing domain (domain I) interacts with a distal region that is sufficient for high affinity binding. To support this model, alanine-scanning mutagenesis was used to assemble a set of 49 PI-SceI mutant proteins that were purified and assayed for their DNA binding and cleavage properties. Fourteen mutant proteins were 4- to >500-fold less active than wild-type PI-SceI in cleavage assays, and one mutant (T225A) was 3-fold more active. Alanine substitution at two positions in domain I reduces overall binding >60-fold by perturbing the interaction of PI-SceI with the minimal binding region. Conversely, mutations in domain II have little effect on binding, reduce binding to the cleavage site region only, or affect binding to both regions. Interestingly, substitutions at Lys301, which is part of the endonucleolytic active site, eliminate binding to the cleavage site region but permit contact with the minimal binding region. This experimental evidence demonstrates that the protein splicing domain as well as the endonuclease domain is involved in binding of a DNA substrate with the requisite length.

[Identification and study on effect of new stress protein from Neisseria gonorrhoeae]

OBJECTIVE

To investigate the influence of changing environmental growth conditions on the virulence of Neisseria gonorrhoeae.

METHODS

The gonococci were subjected to 1 mmol/L hydrogen peroxide (sublethol concentration) for one hour.

RESULTS

A novel gonococcal stress protein with molecular weight of 62,000 was identified by radioactive labeling and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Gonococci exposed to 1.0 mmol/L hydrogen peroxide made it significantly more resistant to higher concentrations of hydrogen peroxide and to neutrophils than control organisms (P < 0.01).

CONCLUSIONS

These results suggest that the 62,000 stress protein might increase the virulence of N. gonorrhoeae and might be an adapted regular protein produced by N. gonorrhoeae survived within human neutrophils.

[Effect of zinc deficiency on apoptosis of spermatogenic cells of rat tostis]

OBJECTIVE

To study the changes of testis apoptosis in zinc deficient rats will promote the understanding of the molecular mechanism of zinc deficiency in the development and function of testis.

METHODS

16 Wistar rats were divided randomly into zinc control group (ZC) and zinc deficiency group (ZD). The serum and testis zinc contents were measured with atomic absorse method; the apoptosis of spermatogenic cells was studied with in situ nick translation (ISNT) technique.

RESULTS

Under zinc deficient status, the zinc contents of the serum and testis were obviously decreased (P < 0.05). The apoptosis number of spermatogenic cells was significantly increased (P < 0.01).

CONCLUSION

The adequate amount of zinc is essential to the development of testis, whereas zinc deficiency can harmfully affect it. This effect is perhaps carried out in different ways, but the increasing apoptosis numbers of spermatogenic cells might be one of molecular miechanisms of the effect of zinc defficiency on testis development.

Functional comparison of the three isoforms of the Na+/Ca2+ exchanger (NCX1, NCX2, NCX3)

Three distinct mammalian Na+/Ca2+ exchangers have been cloned: NCX1, NCX2, and NCX3. We have undertaken a detailed functional comparison of these three exchangers. Each exchanger was stably expressed at high levels in the plasma membranes of BHK cells. Na+/Ca2+ exchange activity was assessed using three different complementary techniques: Na+ gradient-dependent 45Ca2+ uptake into intact cells, Na+ gradient-dependent 45Ca2+ uptake into membrane vesicles isolated from the transfected cells, and exchange currents measured using giant patches of excised cell membrane. Apparent affinities for the transported ions Na+ and Ca2+ were markedly similar for the three exchangers at both membrane surfaces. Likewise, generally similar responses to changes in pH, chymotrypsin treatment, and application of various inhibitors were obtained. Depletion of cellular ATP inhibited NCX1 and NCX2 but did not affect the activity of NCX3. Exchange activities of NCX1 and NCX3 were modestly increased by agents that activate protein kinases A and C. All exchangers were regulated by intracellular Ca2+. NCX1-induced exchange currents were especially large in excised patches and, like the native myocardial exchanger, were stimulated by ATP. Results may be influenced by our choice of expression system and specific splice variants, but, overall, the three exchangers appear to have very similar properties.

[Changes of carbohydrate metabolism in normal pregnancy and its relationship with placental lactogen concentrations]

OBJECTIVE

To observe the changes of glucose metabolism and its relationship with human placental lactogen (HPL) in normal pregnant women.

METHOD

94 normal pregnant women had their serum HPL concentration tested and had undergone a 75 g oral glucose tolerance tests (OGTT). Both serum insulin and glucose levels at different time intervals were determined, and the areas under curve (IAUC, GAUC) were caculated, also insulin resistance (IAI) was evaluated.

RESULTS

GAUC, IAUC, IAI and HPL are all significantly increased with advance of gestation (P < 0.05). Multiple correlation coefficient study demonstrated that HPL is significantly positively correlated with GAUC, IAUC and IAI(P < 0.001). But when IAUC and IAI were controlled, the relationship between HPL and GAUC was not found.

CONCLUSION

There are hyperinsulinemia and insulin resistance during pregnancy, and they are related to HPL. HPL is one of the factors that contributing to carbohydrate metabolism changes during pregnancy.

Ribulose-1,5-bisphosphate carboxylase/oxygenase activase deficiency delays senescence of ribulose-1,5-bisphosphate carboxylase/oxygenase but progressively impairs its catalysis during tobacco leaf development

Transgenic tobacco (Nicotiana tabacum L. cv W38) plants with an antisense gene directed against the mRNA of ribulose-1,5-biphosphate carboxylase/oxygenase (Rubisco) activase grew more slowly than wild-type plants in a CO2-enriched atmosphere, but eventually attained the same height and number of leaves. Compared with the wild type, the anti-activase plants had reduced CO2 assimilation rates, normal contents of chlorophyll and soluble leaf protein, and much higher Rubisco contents, particularly in older leaves. Activase deficiency greatly delayed the usual developmental decline in Rubisco content seen in wild-type leaves. This effect was much less obvious in another transgenic tobacco with an antisense gene directed against chloroplast-located glyceraldehyde-3-phosphate dehydrogenase, which also had reduced photosynthetic rates and delayed development. Although Rubisco carbamylation was reduced in the anti-activase plants, the reduction was not sufficient to explain the reduced photosynthetic rate of older anti-activase leaves. Instead, up to a 10-fold reduction in the catalytic turnover rate of carbamylated Rubisco in vivo appeared to be the main cause. Slower catalytic turnover by carbamylated Rubisco was particularly obvious in high-CO2-grown leaves but was also detectable in air-grown leaves. Rubisco activity measured immediately after rapid extraction of anti-activase leaves was not much less than that predicted from its degree of carbamylation, ruling out slow release of an inhibitor from carbamylated sites as a major cause of the phenomenon. Nor could substrate scarcity or product inhibition account for the impairment. We conclude that activase must have a role in vivo, direct or indirect, in promoting the activity of carbamylated Rubisco in addition to its role in promoting carbamylation.

Signal model of noise in open-loop fiber-optic gyros

The characteristics of noise in fiber-optic gyros are analyzed quantitatively. Based on its physical characteristics and on autocorrelation function evidence, the noise is modeled as the addition of fractal Brownian motion (FBM) and Gaussian white noise (GWN). The value of self-similarlity parameter H in FBM and the intensity of GWN, sigma(w), in the model are robustly determined with an algorithm based on an orthonormal wavelet transform, which demonstrates well the coexistence of the long- and short-term correlation components of the gyro noise. Moreover, it is revealed that FBM dominates the gyro noise, whereas the GWN is minor.

Studies of the catabolic pathway of degradation of nitrobenzene by Pseudomonas pseudoalcaligenes JS45: removal of the amino group from 2-aminomuconic semialdehyde

Pseudomonas pseudoalcaligenes JS45 utilizes nitrobenzene as the sole source of nitrogen, carbon, and energy. Previous studies have shown that degradation of nitrobenzene involves the reduction of nitrobenzene to nitrosobenzene and hydroxylaminobenzene, followed by rearrangement to 2-aminophenol, which then undergoes meta ring cleavage to 2-aminomuconic semialdehyde. In the present paper, we report the enzymatic reactions responsible for the release of ammonia after ring cleavage. 2-Aminomuconic semialdehyde was oxidized to 2-aminomuconate in the presence of NAD by enzymes in crude extracts. 2-Aminomuconate was subsequently deaminated stoichiometrically to 4-oxalocrotonic acid. No cofactors are required for the deamination. Two enzymes, 2-aminomuconic semialdehyde dehydrogenase and a novel 2-aminomuconate deaminase, distinguished by partial purification of the crude extracts, catalyzed the two reactions. 4-Oxalocrotonic acid was further degraded to pyruvate and acetaldehyde. The key enzyme, 2-aminomuconate deaminase, catalyzed the hydrolytic deamination that released ammonia, which served as the nitrogen source for growth of the organism.

[Fermentation conditions of engineering strain utilizing starch for production of alkaline proteinase]

The highest activity of alkaline proteinase produced by Bacillus pumilus c172(pBX 96) transformant was 9,000 U/ml in shaking flask where corn meal and bean cake meal were carbon and nitrogen sources, respectively. The enzyme activity was raised under the conditions of initial pH 7.0, MgCl2 instead of MgSO4, and glucose (0.1%) in the substrate. The fermentation of c172(pBx 96) transformant was carried out with parameters of pH, reducing sugar, total sugar and enzyme activity.

Induction of tolerance to intrathecal butorphanol in rats

BACKGROUND

Butorphanol, an opioid agonist/antagonist, has been administered spinally and epidurally in humans for moderate to severe pain. However, unlike intrathecal (i.t.) morphine, virtually no information is available regarding butorphanol's ability to induce analgesic tolerance at the spinal cord level upon chronic i.t. administration.

METHODS

Continuous infusion of i.t. butorphanol was given via an osmotic minipump. Rats were randomly assigned to four groups (n = 7 each) to receive i.t. infusion (1 microliter/h) consisting of saline, or butorphanol (13, 26, or 52 nmol/h) for 96 h. Tail-flick (TF) latencies were measured during the period of i.t. infusion.

RESULTS

A dose-dependent antinociceptive effect, as measured by TF latency, was demonstrated in the groups receiving i.t. butorphanol as compared to the saline group. The overall antinociceptive effects calculated from the areas under the curve (AUC's) were 372 +/- 3.0, 394 +/- 7.5, and 433 +/- 20 for the 13, 26, and 52 nmol/h butorphanol-infused groups, respectively; the AUC's of the 26 and 52 nmol/h groups were significantly different from the AUC of 356 +/- 3.4 for the saline-infused group (p < 0.01, one way ANOVA; p < 0.05, post hoc Dunnett's test). The TF latencies of the 26 and 52 nmol/h groups were 3.77 +/- 0.05 and 3.73 +/- 0.03 s at the baseline (before the i.t. infusion), respectively; and gradually increased significantly (p < 0.01, two way repeated measure ANOVA; p < 0.05, post hoc Student-Newman-Keuls or SNK test) to the peak values of 4.31 +/- 0.14 and 4.90 +/- 0.28 s, respectively; then decreased significantly from the peaks (p < 0.05, post hoc SNK test) to the final values of 3.87 +/- 0.06 and 4.10 +/- 0.13 s at the end of the 96-h infusion, respectively. The TF values of the saline and the 13 nmol/h groups did not show statistically significant differences throughout the 96-h infusion period.

CONCLUSIONS

Therefore, continuous infusion of i.t. butorphanol at the rate of 26 and 52 nmol/h induced tolerance to tail-flick analgesia within 96 h.

[Tailed normal chromatographic peak expressed by plate model]

An equation for describing tailed normal chromatographic peak is derived based on the plate model. In terms of the de Moivre-Laplace theorem, which states that a binomial distribution can be approximated by the Gaussian distribution for large sample size, it is suggested that the concentration distribution along the distance downstream from the inlet of chromatographic column conforms to the Gaussian distribution function, but the concentration distribution with elution volume (or elution time) does not. The equation developed here, which is similar to the Gaussian distribution function, indicates that the normal chromatographic elution curve should be a tailing one. It is also shown that the symmetric Gaussian elution curve is an approximate solution of the plate model and can be obtained by the approximation of the equation here. The equation is proved to be congruent to the results of the diffusion model. Thus, the plate model and diffusion model are equivalent to each other in describing chromatographic process although different mechanism is based on.

[Cytological study of subretinal fluid]

OBJECTIVES

To determine the cellular components of subretinal fluid and the origin of cells participating in the proliferation in the membranous tissue of proliferative vitreoretinopathy (PVR).

METHODS

35 subretinal fluid samples were studied by cytology using autofluorescent and immunohistochemical assays.

RESULTS

There were a large quantity of retinal pigment epithelium (RPE) and small quantity of pigment epithelial cells originated from epithelial cells of ciliary body and iris, there were also various quantities of neuroretinal cells and macrophages. Neither T-lymphocytes nor B-lymphocytes were found in this group of samples.

CONCLUSIONS

RPE, pigment epithelial cells, neuroretinal cells and macrophages are in subretinal fluid and may participate in the formation and development of PVR in various degrees.

Vanadate activates membranous nonreceptor protein tyrosine kinase in rat adipocytes

The insulin-like effects of vanadate are independent of the insulin receptor and insulin receptor substrate 1 (IRS-1) phosphorylation. A cytosolic protein tyrosine kinase (CytPTK), sensitive to inhibition by nanomolar concentrations of staurosporine (concentration at which 50% inhibition occurs [IC50], 1-2 nmol/l), has been implicated in some (i.e., glucose oxidation, lipogenesis) but not all (i.e., hexose uptake, inhibition of lipolysis) of the insulin-like effects of vanadate. We report here the existence of another nonreceptor protein tyrosine kinase in rat adipocytes, located exclusively in the plasma membranes (MembPTK), which we suggest is associated with hexose uptake and the antilipolytic activity of vanadate. MembPTK is a nonglycoprotein with an estimated molecular weight of 55-60 kDa. In a cell-free experiment, vanadate activates MembPTK seven- to ninefold (median effective dose, 17 +/- 2 micromol/l). Vanadate-activated MembPTK is inhibited by staurosporine (IC50, 60 +/- 5 nmol/l). In intact adipocytes, staurosporine antagonized vanadate-induced hexose uptake (IC50, 6.0 +/- 0.3 micromol/l) and significantly reversed the antilipolytic effect of vanadate (IC50, 5.0 +/- 0.4 micromol/l). After vanadate treatment, a phosphorylated P55 protein is immunoprecipitated by antibodies to both phosphotyrosine and phosphatidylinositol (PI) 3-kinase. In conclusion, rat adipocytes contain an additional vanadate-activatable nonreceptor membranous protein tyrosine kinase that may participate in the effects of vanadate not carried out by CytPTK. We also suggest that after treatment with vanadate, MembPTK is activated by autophosphorylation and interacts with PI 3-kinase. This may explain how vanadate activates PI 3-kinase without involving receptor activation and IRS-1 phosphorylation.

[Genetic divergence of Cordyceps sinensis as estimated by random amplified polymorphic DNA analysis]

Random amplified polymorphic DNA(RAPD) has been used in analyzing 13 winter worm, summer grasses (Cordyceps sinensis [Berk.], Sacc.) from 5 areas in Qingzang plateau. For 19 arbitrary primers, each individual showed about 65 RAPD markers. The genetic distances among those 13 winter worm, summer grasses were correlated to their geographic distances. Molecular phylogenetic tree constructed by UPGMA and NJ suggested that 13 winter worm, summer grasses could be divided into 3 clusters: east cluster, north cluster and middle cluster, in consistence with their origins and genetic divergence among different clusters. Furthermore, our results implied that the RAPD markers of winter worm, summer grasses showed a geographic specificity and could be a better genetic marker in studying genetic diversity and phylogeny of winter worm, summer grasses.

[Effects of low concentration carbon monoxide on human physiological function]

Human volunteers were exposed to various low concentrations of carbon monoxide (CO) in a closed cabin. The results showed that 35 mg/m3 of CO caused slight subjective symptoms and reduction in contrast vision, operating efficiency and T-wave of ECG. At 80 mg/m3 and 115 mg/m3 the above changes were more severe and a rise in hearing threshold level was observed. It demonstrated that an inhibitory effect on the CNS and heart were caused by low concentrations of CO. According to the absorption curves for human exposed to CO, it is suggested that the sense effect level and vision effect level for CO are 7% COHb, and the hearing effect level is 9% COHb.