[Analysis of volatile organic components of organic solvents used in Bao'an District of Shenzhen].

Objective: To understand the volatile organic components in the organic solvents used by enterprises in Baoan District, Shenzhen. Methods: From January to December 2020, a total of 541 organic solvent samples used by 86 companies were collected for volatile organic component analysis, and the main volatile components and high-risk occupational hazards in organic solvents used in different industries were analyzed. Results: A total of 201 volatile organic components were detected in 541 organic solvents. The top 5 components detected include xylene (29.76%, 116/541), toluene (21.81%, 118/541), methanol (20.70%, 112/541), n-hexane (14.79%, 80/541) and ethylbenzene (14.23%, 77/541). The detection rates of benzene, trichloroethylene, n-hexane, and 1, 2-dichloroethane, which were high-risk occupational hazards, were 2.40% (13/541), 3.70% (20/541), 14.79% (80/541), and 1.66% (9/541), respectively. The volatile components in organic solvents used in different industries was different. Benzene is more frequently detected in organic solvents used in the printing industry, trichloroethylene was more frequently detected in organic solvents used in the electronics industry, and n-hexane was more commonly found in organic solvents used in the electronics industry, printing and other industries, and 1, 2-dichloroethane has been more frequently detected in organic solvents used in the machinery industry. Conclusion: There are many types of organic solvents used by enterprises in Bao'an District, with complex components and differences in different industries.

[A survey of cervical and lumbar spine diseases of express delivery employees].

Objective: To understand the current situation and influencing factors of cervical and lumbar spine diseases of the express delivery employees, and provide scientific basis for carrying out their occupational health protection in a targeted manner. Methods: From February 2020 to January 2021, the current situation research method was used to obtain 527 express delivery employees by cluster sampling. Online questionnaires were used to investigate sociodemographic characteristics and emotional characteristics, and clinical data were obtained by digital X-ray (DR) examination of the neck and waist. Pearson χ(2) test and multivariate logistic regression were used to analyze the influencing factors of cervical and lumbar spine diseases in express delivery employees. Results: The prevalence rates of cervical spine and lumbar spine diseases among express delivery employees were 49.15% (259/527) and 67.74% (357/527) , respectively. Univariate analysis showed that there were statistically significant differences in the distribution of cervical and lumbar spine disease among express delivery employees with different ages, length of service, working hours per week, and different degrees of distress due to emotional factors (P<0.05) . Multivariate analysis showed that express delivery employees aged ≥25 years old had a higher risk of cervical spine disease (P<0.05) , the express delivery employees who worked 49-55 hours per week had a lower risk of cervical spine disease (P<0.05) . Express delivery employees aged≥35 years old had a lower risk of lumbar spine disease (P<0.05) , and the risk of lumbar spine disease was higher among express delivery workers who suffered moderate or more distress due to emotional factors (such as anxiety, depression, or irritability) in the past 4 weeks (P<0.05) . Conclusion: The prevalence of cervical and lumbar spine diseases is relatively high among express delivery employees. It is recommended to adjust the weekly working hours of express delivery employees, organize psychological counseling training, and effectively protect the occupational health rights of express delivery employees.

[Investigation on occupational injury of sanitation workers in Shenzhen City].

Objective: To understand the occurrence of occupational injuries among sanitation workers in Shenzhen, and provide a scientific basis for the prevention of occupational injuries among sanitation workers. Methods: From May to November 2020, a cluster sampling method was used to select some street sanitation workers in Shenzhen to conduct a questionnaire survey. A total of 2200 questionnaires were recovered, of which 2167 were valid (98.5% effective recovery rate) . The socio-demographic data, length of service, type of work and occurrence of occupational injuries of sanitation workers were collected, and the distribution characteristics of occupational injuries and their relationship with factors such as type of work were analyzed. Results: Among the 2167 sanitation workers, 240 (11.1%) had experienced occupational injuries. The most common occupational injuries among sanitation workers were sharp injury, heat stroke and motor vehicle traffic accident, with the incidence rates of 6.1% (133/2167) , 2.4% (53/2167) and 1.7% (36/2167) respectively. There were statistically significant differences in the distribution of occupational injuries among sanitation workers with different lengths of work and types of work (P<0.05) . The incidence of occupational injury among sanitation workers with more than 5 years of service was significantly higher than that of workers with less than 5 years of service (P<0.05) . The incidence of sharp injury among garbage sorting and transportation personnel was higher (7.9%, 21/265) , the incidence of heat stroke among manual cleaners was higher (3.1%, 42/1366) , and the incidence of motor vehicle traffic accident among mechanized cleaners was higher (5.4%, 10/184) . Conclusion: There are many cases of occupational injuries among sanitation workers in Shenzhen. Targeted measures should be taken to prevent the occurrence of different types of work and different types of occupational injuries, and to improve the occupational health level of sanitation workers.

[A preliminary comparison on ophthalmic examination indices of workers with different occupations in Shenzhen].

Objective: To compare the ophthalmic examination indices of different occupational groups in Shenzhen and analyze the possible health problems, so as to provide research basis for further health intervention. Methods: In March 2021, 5426 professionals with ophthalmic examination index data were selected from the basic health database of "Shenzhen occupational population protection action". Among them, radiation workers (694), port operators (1756), sanitation workers (946), teachers (224), video workers (154), police (927) and firefighters (100) were selected as the investigated occupational population. They were exposed to noise 625 workers with traditional occupational hazards such as noise, chemical poisons and dust were used as the control population.Ophthalmic examination indices included right eye vision, left eye vision, outer eye, conjunctiva, cornea, lens, and fundus oculi. The differences of each index in different occupational groups were compared. Results: Compared with the control group, the port operator group showed lower abnormal rates of binocular vision and fundus oculi (P<0.05), but higher abnormal rates of conjunctiva (P=0.029), the environmental sanitation worker group showed higher abnormal rates of binocular vision and conjunctiva (all P<0.01), the teacher group had higher abnormal rates of binocular vision, but only the difference of left eye vision was statistically significant (P=0.021), and the video worker group had higher abnormal rates of right and left eyes vision (P=0.029、0.006) . Conclusion: There were some degrees of ophthalmic problems in different occupational population, therefore targeted intervention measures should be taken according to the characteristics of each group.

Data-driven machine-learning analysis of potential embolic sources in embolic stroke of undetermined source.

BACKGROUND AND PURPOSE: Hierarchical clustering, a common 'unsupervised' machine-learning algorithm, is advantageous for exploring potential underlying aetiology in particularly heterogeneous diseases. We investigated potential embolic sources in embolic stroke of undetermined source (ESUS) using a data-driven machine-learning method, and explored variation in stroke recurrence between clusters. METHODS: We used a hierarchical k-means clustering algorithm on patients' baseline data, which assigned each individual into a unique clustering group, using a minimum-variance method to calculate the similarity between ESUS patients based on all baseline features. Potential embolic sources were categorised into atrial cardiopathy, atrial fibrillation, arterial disease, left ventricular disease, cardiac valvulopathy, patent foramen ovale (PFO) and cancer. RESULTS: Among 800 consecutive ESUS patients (43.3% women, median age 67 years), the optimal number of clusters was four. Left ventricular disease was most prevalent in cluster 1 (present in all patients) and perfectly associated with cluster 1. PFO was most prevalent in cluster 2 (38.9% of patients) and associated significantly with increased likelihood of cluster 2 [adjusted odds ratio: 2.69, 95% confidence interval (CI): 1.64-4.41]. Arterial disease was most prevalent in cluster 3 (57.7%) and associated with increased likelihood of cluster 3 (adjusted odds ratio: 2.21, 95% CI: 1.43-3.13). Atrial cardiopathy was most prevalent in cluster 4 (100%) and perfectly associated with cluster 4. Cluster 3 was the largest cluster involving 53.7% of patients. Atrial fibrillation was not significantly associated with any cluster. CONCLUSIONS: This data-driven machine-learning analysis identified four clusters of ESUS that were strongly associated with arterial disease, atrial cardiopathy, PFO and left ventricular disease, respectively. More than half of the patients were assigned to the cluster associated with arterial disease.

Reduced risk of new onset stroke after kidney transplantation in Asian dialysis patients: a propensity score-matched, competing risk study in Taiwan.

BACKGROUND: Kidney transplantation (KT) has been found to reduce cardiovascular events and mortality in chronic dialysis patients. There is little data, however, regarding the risk reduction of cerebrovascular events after KT in Asian populations. This study evaluates the risk of cerebrovascular events after KT in Taiwan. METHODS: Tapping Taiwan's National Health Insurance claims data of patients with a diagnosis of end-stage renal disease (ESRD), we enrolled all KT recipients from 1999 to 2011 (n = 2908). For each KT patient, four controls (patients also diagnosed with ESRD) without KT were propensity matched by birth date, sex, selected comorbidities and duration of dialysis. All subjects were followed to the end of 2011. RESULTS: The incidence rate for stroke in the KT recipients and comparison group were 52.63 and 137.26 per 10 000 person-years, respectively. After adjustment for age, gender and comorbidities with competing mortality, KT recipients had 60% reduction in all kinds of stroke, compared to those who did not receive procedure. They were found to have a 48 and 74% reduction in ischemic and hemorrhagic stroke risk, respectively. Subgroup analyses also showed similar trends in the improvement of stroke after KT. While elderly patients, men, and those with diabetes, hypertension and coronary artery disease are at increased risk for stroke, our log-rank test revealed those that received KT had significantly lower cumulative incidence rates of stroke than those that did not (P < 0.001). CONCLUSIONS: KT was associated with reduced risk of new onset stroke in chronic dialysis patients in Taiwan.

Long-term risk of stroke in type 2 diabetes patients with diabetic ketoacidosis: A population-based, propensity score-matched, longitudinal follow-up study.

AIM: To investigate the long-term risk of stroke in type 2 diabetes (T2D) patients with previous episodes of diabetic ketoacidosis (DKA). METHODS: This retrospective nationwide population-based cohort study was conducted using Taiwan's National Health Insurance database. Claims data from 2000 to 2002 were extracted for 3572 T2D patients with DKA and 7144 controls matched for age, gender, diabetes complications severity index, frequency of clinical visits and baseline comorbidities. Patients with type 1 diabetes (T1D), identified by glucagon C-peptide stimulation or glutamic acid decarboxylase (GAD) antibody blood tests and possession of a catastrophic illness certificate were excluded. All patients were tracked until a new stroke diagnosis, death or the end of 2011. RESULTS: Of the 3572 selected patients, 270 with DKA and 404 of the 7144 controls were diagnosed with a new stroke, giving an incidence rate ratio (IRR) of 1.56 (95% CI: 1.34-1.82; P<0.0001). DKA patients had a higher risk of ischaemic stroke than those without DKA (IRR: 1.62, 95% CI: 1.34-1.96; P<0.0001), and DKA patients with hypertension and hyperlipidaemia were at even greater risk of stroke. Also, DKA patients were at particular risk for stroke during the first half-year following DKA diagnosis. After adjusting for patient characteristics and comorbidities, these patients were 1.55 times more likely to have a stroke than those without DKA (95% CI: 1.332-1.813, P<0.0001). CONCLUSION: T2D patients with previous DKA have a higher risk of stroke, especially ischaemic strokes.

Increased risk of sudden sensorineural hearing loss in patients with depressive disorders: population-based cohort study.

OBJECTIVES: To evaluate the incidence rates and risk of sudden sensorineural hearing loss among patients with depressive disorders. METHOD: Data for 27 547 patients with newly diagnosed depressive disorders and 27 547 subjects without depressive disorders between 2001 and 2008 were yielded from the Taiwan National Health Insurance Research Database. Sudden sensorineural hearing loss incidence at the end of 2011 was determined. Cumulative incidence and adjusted hazard ratio were computed. RESULTS: Sudden sensorineural hearing loss incidence was 1.45 times higher in the depressive disorders group compared to the non-depressive disorders group (p = 0.0041), with an adjusted hazard ratio of 1.460. A significant increased risk of developing sudden sensorineural hearing loss was noted in patients with diabetes mellitus, chronic kidney disease and hyperlipidaemia (p < 0.05). CONCLUSION: The results suggest an increased risk of developing sudden sensorineural hearing loss in patients with depressive disorders. Co-morbidities such as diabetes mellitus, chronic kidney disease and hyperlipidaemia significantly aggravated the risk. Depressive disorders might be considered a risk factor for sudden sensorineural hearing loss. It remains to be seen whether control of depressive disorders can decrease the incidence of sudden sensorineural hearing loss in patients with depressive disorders.

Increased risk of pulmonary tuberculosis in patients with previous non-tuberculous mycobacterial disease.

OBJECTIVE: To investigate whether or not there is an increased risk of pulmonary tuberculosis (PTB) after non-tuberculous mycobacterial (NTM) disease. DESIGN: A retrospective cohort study of 212 NTM patients and 4240 control cases. RESULTS: Patients with previous NTM disease had a significantly higher incidence of PTB than controls (incidence rate ratio [IRR] 14.74, 95%CI 8.71-24.94, P < 0.0001). Cox's proportional hazards analysis yielded an adjusted hazards ratio (aHR) of 10.15 (95%CI 5.67-18.17, P < 0.05) for NTM-associated PTB. The majority of the PTB cases (17/23, 73.9%) were diagnosed within 6 months after the diagnosis of NTM disease. Older age (≥65 years, aHR 4.45, 95%CI 1.94-10.22, P < 0.05), male sex (aHR 1.75, 95%CI 1.01-3.13, P < 0.05), human immunodeficiency virus (HIV) infection (aHR 12.49, 95%CI 3.20-48.79, P < 0.05) and chronic obstructive pulmonary disease (aHR 4.46, 95%CI 2.19-9.10, P < 0.05) were independent risk factors for developing PTB after NTM disease. The cumulative incidence of PTB in patients with previous NTM disease was significantly higher than in controls (P < 0.0001, Kaplan-Meier analysis). However, there was no significant difference in the survival rates in the two cohorts. CONCLUSION: Increased PTB prevalence after NTM disease was demonstrated. HIV infection was the greatest independent risk factor for subsequent development of PTB.

Hyperthyroidism and thyroid cancer risk: a population-based cohort study.

AIM: Thyroid hormones regulate the rate of metabolism and affect the differentiation and growth of many tissues in the body. We investigated the association between hyperthyroidism and cancer risk in Taiwan. PATIENTS AND METHODS: A random sample of 1 000 000 individuals from Taiwan's National Health Insurance database was enrolled. We found 17 033 patients to have newly diagnosed hyperthyroidism between 2000 and 2005. These patients were recruited along with a match cohort of 34 066 patients without hyperthyroidism. Starting from index date, we followed up all patients for 4 years to identify those who developed cancer. RESULTS: During the 4-year follow-up study, cancer was diagnosed in 1.23% of patients with hyperthyroidism and 1.02% of the member of the comparison cohort. Regression analysis showed that patients with hyperthyroidism were at greater risk of cancer incidence, especially thyroid cancer, compared the comparison cohort (HR: 1.213; 95% CI: 1.022-1.440; p<0.05 and HR: 7.355; 95% CI: 3.885-13.92; p<0.05, respectively). After adjusting for age, gender, diabetes mellitus, hypertension, hyperlipidemia, gout, geographic region, and income, patients with hyperthyroidism remained at increased risk of cancer incidence and thyroid cancer (Adjusted HR: 1.206; 95% CI: 1.015-1.433 and 6.803; 95% CI: 3.584-12.91, respectively) (both p<0.05). The longer the duration of hyperthyroidism, the greater the risk of thyroid cancer. CONCLUSIONS: This 4-year follow up study suggests that patients with hyperthyroidism are at increased risk of cancer, especially thyroid cancer.

Extrapulmonary tuberculosis: a study comparing diabetic and nondiabetic patients.

PURPOSE: The previous studies of extrapulmonary tuberculosis (EPTB) have not focused on the impacts of diabetes mellitus. We conducted a retrospective study to explore the difference between EPTB patients with and without diabetes. METHODS: The EPTB patients receiving initial treatments from Taipei Medical University Hospital between January 2003 and March 2008 were recruited. They were divided into with-diabetes (WD) group or non-diabetes (ND) group according to coexistence of diabetes mellitus or not, respectively. All characteristics of these two groups were compared. RESULTS: Seventy-five patients were enrolled into our study. Fifteen patients and 60 patients were recruited into WD and ND groups, respectively. The basic characteristics and tuberculosis sites of the two groups were compared. The prevalence of hypertension (66.7% vs. 38.3%, p=0.048) and chronic liver diseases (33.3% vs. 3.3%, p=0.003) in WD group were higher than in ND group. The incidence of tuberculous peritonitis in WD group was higher than in ND group (26.7% vs. 6.7%, p=0.046). The odds ratio of tuberculous peritonitis for WD group was 5 091 (95% CI 1.103-23.493, p=0.037). The random glucose level (10.9+/-5.8 vs. 6.8+/-1.6 mmol/L, p=0.025), the fasting glucose level (8.6+/-4.4 vs. 5.6+/-0.9 mmol/L, p=0.038), and the hemoglobin A1c level (7.4+/-1.1 vs. 5.6+/-0.4%, p=0.037) were higher in WD group than in ND group. The total bilirubin level was higher in WD group than in ND group (18.4+/-6.2 vs. 13+/-7.2 micromol/L, p=0.042). Presenting symptoms and other laboratory data were not different statistically between these two groups. CONCLUSIONS: This is the first study about the impacts of diabetes on EPTB. The prevalence of hypertension and chronic liver diseases, the incidence of tuberculous peritonitis, and the total bilirubin level were higher in EPTB patients with diabetes than those without diabetes.

The interaction of Cu2 + ions and NaDC micelles.

By mixing an aqueous solution of CuCl2 with an NaDC aqueous solution of various concentration and initial molar ratio, seven coordinated samples with distinct appearances and characters were obtained. Their structures and components were investigated by FT-IR spectroscopy, EXAFS (the extended X-ray absorption fine structure), thermal analysis, X-ray diffraction, laser light scattering, TEM (transmission electron micrograph), element analysis and ICP (inductively coupled plasma) analysis. The following conclusions were given: (1) The complexes of Cu2+-NaDC with distinct appearances and properties were synthesized. (2) After Cu(DC)2 dissolved in NaDC aqueous solution, larger micelles (30-90 nm diameter) formed in the supernate, it is a mixed micelle with Cu(DC)2 and NaDC. So these micelles are a new kind of micelle containing two kinds of metal ions. This is a new result using metal ions as bridges to form micelle. (3) According to the different concentration of Cu2+ to NaDC, the complexes formed as gel or poly-crystals. Both the composition of gel complexes and the coordination structure of carboxyl groups with metal ions varied with the initial molar ratio of Cu2+ to Na+. The gel complexes exhibits the non-stoichiometric character. (4) These results are in agreement with physiological condition. All the different states such as gel, precipitate, micelles of various structures are present in bile of gallbladder. We can suggest an ideal model of the interaction between Cu2+ and bile salts in vivo.

Sequence, transcriptional analysis and chromosomal location of the Xanthomonas campestris pv. campestris uvrB gene.

The uvrB gene of Xanthomonas campestris pv. campestris, a Gram-negative plant pathogenic bacterium inhabiting soil and infected plants, was cloned and sequenced. This gene has the capacity to encode a polypeptide of 673 amino acid residues with a calculated molecular mass of 75.9 kDa. Its deduced amino acid sequence shows a high degree of similarity and possesses domain conservation to those of bacterial UvrB. The uvrB mutant, isolated by gene replacement, is extremely sensitive to ultraviolet irradiation. Like the situation in the X. campestris pv. campestris recA gene, no SOS box is present upstream of the uvrB gene. Northern blotting and transcriptional fusion assay with lacZ indicated that X. campestris pv. campestris uvrB is expressed constitutively at high levels and cannot be further induced by UV irradiation. These results suggest a regulatory mechanism different from that for the expression of Escherichia coli uvrB. Using a gene-tagging strategy in conjunction with pulsed-field gel electrophoresis, the uvrB gene was located near 1 o'clock on the X. campestris pv. campestris 17 chromosome (4.8 Mb) map, which is far apart from the lexA-recA-recX cluster near 5 o'clock.

UDP-glucose dehydrogenase gene of Xanthomonas campestris is required for virulence.

Xanthomonas campestris pv. campestris (Xc) is the casual agent of black rot in crucifers. The Xc gene (udgH) coding for UDP-glucose dehydrogenase, an enzyme catalyzing the conversion of UDP-glucose to UDP-glucuronic acid, was previously shown to be required for the biosynthesis of xanthan gum, a substance necessary for the bacterium to cause disease. In this study, the transcription start site of the udgH was determined and the promoter activity monitored by the xylE reporter system indicated that expression of the udgH increases following cell growth and that the udgH gene may possess a second promoter that is responsive to stationary-phase change retaining high levels of expression. Results of Southern hybridization suggest that the udgH gene may be ubiquitous in Xanthomonas, coincident with the notion that members of this genus are capable of xanthan gum biosynthesis. Mutation of the udgH gene in Xc and X. campestris pv. vesicatoria, the casual agent of leaf spot in pepper and tomato, was found to cause a loss of virulence.

Characterization of stress-responsive genes, hrcA-grpE-dnaK-dnaJ, from phytopathogenic Xanthomonas campestris.

Sequencing of a 6.4-kb DNA fragment, cloned from the plant pathogenic bacterium Xanthomonas campestris pv. campestris 17 revealed five ORFs whose deduced amino acid sequences show strong similarities to the bacterial HrcA, GrpE, DnaK, DnaJ, and PdxK. The four heat shock genes are organized in the order hrcA-grpE-dnaK-dnaJ, a genome organization found in many gram-positive bacteria, but only in one gram-negative species (Xylella fastidiosa). These observations suggest that the HrcA-CIRCE system, comprising at least four genes arranged in this order, already existed for the regulation of stress responses before bacteria diverged into gram-negative and gram-positive groups. Primer-extension results suggested the presence of promoters at the regions upstream of grpE and dnaK. In the presence of stress, heat or ethanol (4%), the X. campestris pv. campestris 17 grpE and dnaK promoters were induced two- to three-fold over controls. Since the grpE and dnaK promoters possess E. coli sigma(32) promoter-like sequences, they are functional in E. coli, although at levels much lower than in X. campestris pv. campestris 17. Furthermore, expression of the X. campestris pv. campestris 17 dnaK promoter in E. coli was elevated by the cloned X. campestris sigma(32) gene, indicating that the cognate sigma(32) works more efficiently for the X. campestris promoters.

Riboflavin synthesis genes ribE, ribB, ribH, ribA reside in the lux operon of Photobacterium leiognathi.

Nucleotide sequence of the riboflavin synthesis genes ribE, ribB, ribH, ribA (GenBank Accession No. AF364106) resided in the lux operon of Photobacterium leiognathi PL741 has been determined, and the amino acid sequences of riboflavin synthetase (RibE), DHBP synthetase (RibB), lumazine synthetase (RibH), GTP cyclohydrolase II (RibA) encoded by the riboflavin synthesis genes are deduced. Nucleotide sequence reveals that the ribE gene encodes the riboflavin synthetase responsible for converting lumazine to riboflavin, the ribB gene encodes the DHBP synthetase responsible for 3,4-dihydroxyl-2-butanone 4-phosphate synthesis, the ribH gene encodes the lumazine synthetase responsible for lumazine synthesis, and the ribA gene encodes the GTP cyclohydrolase II responsible for lumazine synthesis. Functional analysis illustrates that the specific segments lay behind the ribH and ribA genes might form potential loops Omega(oT) and Omega(TI)--Omega(TII); Omega(oT) is functioned as mRNA stability loop or/and for subregulation by alternative modulation, and Omega(TI)--Omega(TII) could be the transcriptional terminator of the lux operon. The gene order of the ribE, ribB, ribH, ribA genes resided in the lux operon and linked to the lum operon is <--ter*-lumQ-lumP-R&R-luxC-luxD-luxA-luxB-luxN-luxE-luxG-ribE-ribB-ribH-ribA-ter--> (R&R: regulatory region; ter: transcriptional terminator), whereas the R&R is the regulatory region for the lum and the lux operons, and ter and ter* are the transcriptional terminators for the lux and lum operons.

Distinguishing malignant from normal oral tissues using FTIR fiber-optic techniques.

Oral tissue samples were studied using mid-IR fiber-optic attenuated total reflectance spectroscopy and other spectral techniques. The 1745 cm(-1) band, which is assigned to the ester group (C==O) vibration of triglycerides, is a reliable marker that is present in normal tissues but absent or a weak band in malignant oral tissues. Other bands such as C--H stretching bands and the amide bands are also helpful in distinguishing malignant tissues from normal tissues. Subtraction spectra confirmed the above conclusion. In addition, Raman spectroscopic measurements were in agreement with the results observed from FTIR spectra.

The early stages of filamentous phage phiLf infection require the host transcription factor, Clp.

Xanthomonas campestris pv. campestris produces great amounts of an exopolysaccharide (EPS), xanthan gum. Eight eps loci involved in biosynthesis of the EPS were previously located in the chromosome map of strain Xc17. In this study, the eps8 region was cloned, sequenced and found to contain a crp homologue whose deduced amino acid sequence possesses similarity to that of the cyclic AMP receptor protein of bacteria, with the highest identity (97%) being shared with the X. campestris pv. campestris B-1459 clp gene previously shown to be involved in pathogenicity and regulation of the production of xanthan, extracellular enzymes, and pigment (de Crecy-Lagard V., Glaser P., Lejeune P., Sismeiro O., Barber C.E., Daniels M.J., and Danchin A., J. Bacteriol. 172:5877-5883, 1990). Based on sequence identity, pleiotropic effects of the mutation, the ability to complement an Escherichia coli cya crp mutant, and Southern hybridization detecting a single copy in the chromosome, we propose this eps8 gene to be the Xc17 clp. In addition to the previously reported properties, a clp mutant (AU56E) cannot be plaqued with filamentous phage phiLf, although it retains the capability to support phiLf DNA replication and release authentic phage particles upon electroporation of the RF DNA. Infective center assays demonstrated that the frequency of infection is 460- to 7,500-fold lower in AU56E compared to that in the wild-type Xc17. Electron microscopy, which showed no surface appendages other than the monotrichous flagellum, confirmed that AU56E drastically diminishes in the efficiency of phage adsorption. These results suggest Clp to be regulating the biosynthesis of the primary receptor, most likely a type IV pilus. Upstream to clp is a homologue of the E. coli speD gene required for spermidine synthesis. Mutation of the clp flanking regions and transcriptional analyses suggest clp to be monocistronic and the only gene contained at the eps8 locus.

[Synthesis and spectroscopic properties of rare earth complexes with o-phthalate and 1,10-phenanthroline].

The complexes of rare earth ions (Nd3+, Sm3+) with o-phthalate and 1,10-phenanthroline have been synthesized and characterized by elemental analysis, 1H NMR, IR, and DTA-TG. The compositions of complexes have been confirmed to be RE2L3.2H2O and RE2L3 phen.2H2O (RE: rare earth ions, L: o-phthalic, phen: 1,10-phenanthroline), their far-IR and FT-Raman spectra have been discussed and studied.

Sugar interaction with metal ions. Crystal structure and FT-IR spectroscopic study of strontium galactarate mono-hydrate.

The crystal structure of strontium galactarate mono-hydrate, Sr2+ x C6H8O8(2-) x H2O, Mr = 313.76, monoclinic, P2(1)/c, a = 10.268(2), b = 10.333(2), c = 10.194(2) A, beta = 117.87(3) degrees, lambda(Mo K alpha) = 0.71073 A, Z = 4, Dx = 2.180 Mg m(-3), V = 956.1(3) A3, mu = 5.676 mm(-1), F(000) = 624, T = 293(2) K, R = 0.0260 for 1690 observed reflections and 145 parameters refined, has been determined. The galactarate ion is centro-symmetrical in the crystal structure, although it contains independent half-ions. The Sr2+ ion is nine-coordinated (tricapped trigonal prism) with five Sr-O bonds from carboxylic groups, and four from hydroxyl groups. The water molecule does not take part in the coordination. Six hydrogen bonds are formed, three of them related to the water molecule. The spectroscopic evidence shows that the carboxylic acid dimers of the free acid dissociate. The asymmetric stretching vibrations of the anionic COO groups in the salt are observed at 1609 and 1548, and 1581 cm(-1), assigned to a mono-dentate and a tetra-dentate coordination, respectively. The symmetric stretching vibration is located at 1397 cm(-1). The hydroxyl groups of the galactarate skeleton take part in the metal-oxygen interaction, and the hydrogen-bonding network is rearranged upon sugar metalation.