Falling perinatal mortality in twins in the UK: organisational success or chance?

In June 2018, Mothers and Babies Reducing Risks through Audits and Confidential Enquiries across the UK (MBRRACE-UK) published a Perinatal Surveillance report of an audit between 2013-2016. This noted that the stillbirth rate for twins nearly halved between 2014-2016; whereas the stillbirth rate for singletons remained static. There was a statistically significant reduction in the rate of stillbirth in twins over this period from 11.07 (95% CI, 9.78-12.47) to 6.16 (95% CI, 5.20-7.24) per 1000 total births. This commentary discusses these observations, the effects of twin chorionicity, and the potential obstetric and neonatal interventions, as well as public health improvements, that may have influenced these findings.

Canadian survey on pandemic flu preparations

Background

The management of pandemic influenza creates public health challenges.

An ethical framework, 'Stand on Guard for Thee: ethical considerations in pandemic influenza preparedness' that served as a template for the World Health Organization's global consultation on pandemic planning, was transformed into a survey administered to a random sample of 500 Canadians to obtain opinions on key ethical issues in pandemic preparedness planning.

Methods

All framework authors and additional investigators created items that were pilot-tested with volunteers of both sexes and all socioeconomic strata. Surveys were telephone administered with random sampling achieved via random digit dialing (RDD). Eligible participants were adults, 18 years or older, with per province stratification equaling provincial percent of national population. Descriptive results were tabulated and logistic regression analyses were used to assess whether demographic factors were significantly associated with outcomes.

Results

5464 calls identified 559 eligible participants of whom 88.5% completed surveys. Over 90% of subjects agreed the most important goal of pandemic influenza preparations was saving lives, with 41% endorsing saving lives solely in Canada and 50% endorsing saving lives globally as the highest priority. Older age (OR = 8.51, p < 0.05) and current employment (OR = 9.48, p < 0.05) were associated with an endorsement of saving lives globally as highest priority. About 90% of respondents supported the obligation of health care workers to report to work and face influenza pandemic risks excepting those with a serious health condition that increased risks. Over 84% supported the government's provision of disability insurance and death benefits for health care workers facing elevated risk. Strong majorities favored stocking adequate protective antiviral dosages for all Canadians (92%) and, if effective, influenza vaccinations (95%). Over 70% agreed Canada should provide international assistance to poorer countries for pandemic preparation, even if resources for Canadians were reduced. While 92% of this group, believed provision should be 7 to 10% of all resources generated, 43% believed the provision should be greater than 10%.

Conclusions

Results suggest trust in public health officials to make difficult decisions, providing emphasis on reciprocity and respect for individual rights.

Clinical ethicists' perspectives on organisational ethics in healthcare organisations

BACKGROUND

Demand for organisational ethics capacity is growing in health organisations, particularly among managers. The role of clinical ethicists in, and perspective on, organisational ethics has not been well described or documented in the literature.

OBJECTIVE

To describe clinical ethicists' perspectives on organisational ethics issues in their hospitals, their institutional role in relation to organisational ethics, and their perceived effectiveness in helping to address organisational ethics issues.

DESIGN AND SETTING

Qualitative case study involving semi-structured interviews with 18 clinical ethicists across 13 health organisations in Toronto, Canada.

RESULTS

From the clinical ethicists' perspective, the most pressing organisational ethics issues in their organisations are: resource allocation, staff moral distress linked to the organisation's moral climate, conflicts of interest, and clinical issues with a significant organisational dimension. Clinical ethicists were consulted in particular on issues related to staff moral distress and clinical issues with an organisational dimension. Some ethicists described being increasingly consulted on resource allocation, conflicts of interest, and other corporate decisions. Many clinical ethicists felt they lacked sufficient knowledge and understanding of organisational decision-making processes, training in organisational ethics, and access to organisational ethics tools to deal effectively with the increasing demand for organisational ethics support.

CONCLUSION

Growing demand for organisational ethics expertise in healthcare institutions is reshaping the role of clinical ethicists. Effectiveness in organisational ethics entails a re-evaluation of clinical ethics training to include capacity building in organisational ethics and organisational decision-making processes as a complement to traditional clinical ethics education.

Prediction of preterm delivery in twin pregnancy: a prospective, observational study of cervical length and fetal fibronectin testing

OBJECTIVE

To evaluate prospectively cervical length measurements and fetal fibronectin detection as predictors of spontaneous preterm delivery in an unselected population of twin pregnancies.

METHODS

Transvaginal ultrasound assessments of cervical length were performed serially at 18, 24, 28 and 32 weeks' gestation. Receiver-operating characteristic curves were generated at each time point to determine the optimal cut-off for cervical length and rate of change in cervical length in the prediction of preterm delivery (< 35 weeks). A bedside assay for the detection of fetal fibronectin in the maternal vaginal secretions was performed prior to cervical length measurements from 24 weeks. Likelihood ratios (LRs) were used to assess the performance of each test.

RESULTS

The spontaneous preterm delivery rate was 16.5% in 91 studied twin pregnancies. A cervical length </= 25 mm at 18 weeks (LR+ 9.7, sensitivity 14.3%) and </= 22 mm at 24 weeks (LR+ 9.6, sensitivity 28.6%) were the best predictors of preterm delivery. A shortening of cervical length >/= 2.5 mm per week between 18 and 28 weeks' gestation also predicted preterm delivery (LR+ 10.8, sensitivity 16.7%). There was no relationship between the detection of fetal fibronectin and preterm delivery.

CONCLUSIONS

This study confirms the value of transvaginal ultrasound assessment of cervical length as a predictor of preterm delivery in twin pregnancies. However, the poor sensitivity of this test makes it unsuitable as a single predictor of preterm delivery. Fetal fibronectin testing does not identify twin pregnancies destined to deliver prematurely.

Analysis of diversity among 3-chlorobenzoate-degrading strains of Rhodopseudomonas palustris

The phenotypic and genetic characteristics of 14 strains of the purple nonsulfur bacterium Rhodopseudomonas palustris were studied to assess diversity within this species. While all strains had certain phenotypic characteristics in common, including the ability to metabolize benzoate and degrade 2- and 3-chlorobenzoate, there were also significant differences among the strains such as the rate of growth in media containing benzoate as a carbon source. Genetic characterization of the strains revealed there were three divergent lineages in the species. Based on 16S rRNA gene sequences, the 14 strains could be grouped into three distinct clusters (A, B, and C), and this clustering was congruent with that based on gene sequences of form II ribulose-1,5-bisphosphate carboxylase/oxygenase (RubisCO). Although BOX-PCR genomic DNA fingerprints of all 14 strains exhibited differences, analysis of the fingerprint images and UPGMA/product-moment analysis of similarities showed there were three groupings that were entirely consistent with clusters based on other characteristics of the strains. Thus, regardless of the method of analysis used, strains in groups A and B consistently clustered together and were separate from those of group C. These results suggest that strains in groups A-B and C represent phylogenetically related clones that have diverged from one another. This indicates that at least three lineages of Rhodopseudomonas palustris exist among the strains included in this study, and that each may be particularly well adapted to a distinct ecological niche.

Effect of ketorolac and low-molecular-weight heparin individually and in combination on haemostasis

Low-molecular-weight heparins, when used in surgical patients for thromboprophylaxis, may be used concurrently with ketorolac, a non-steroidal anti-inflammatory drug that is used for analgesia. Because these two agents can influence the haemostatic system, it is important to identify any such effect. The haemostatic interaction between dalteparin and ketorolac was assessed in a double-blind, placebo-controlled, randomized, crossover study of healthy male volunteers each given all four combinations of ketorolac/placebo and dalteparin/placebo. The effect of ketorolac and dalteparin on haemostasis was assessed by measuring in-vitro platelet aggregation, anti-factor-Xa, activated partial thromboplastin times and skin bleeding time. The results were analysed for evidence of an interaction between ketorolac and dalteparin. Ketorolac inhibited platelet aggregation in whole blood and platelet-rich plasma. The administration of dalteparin led to a significant increase in levels of anti-factor-Xa and a significant prolongation in the activated partial thromboplastin time, although it remained within the range of the normal population. There was no evidence of any interaction between ketorolac and dalteparin with regard to platelet aggregation, anti-factor-Xa activity or activated partial thromboplastin time. The administration of ketorolac significantly prolonged the skin bleeding time. There was a significant interaction between ketorolac and dalteparin to prolong the bleeding time, although dalteparin alone had no effect on bleeding time. There was an interaction between ketorolac and dalteparin, which affected bleeding times. Such an interaction raises the possibility of haemorrhagic complications developing perioperatively when these agents are used concomitantly. Further studies are required to examine the clinical importance of this interaction.

Increased nitrotyrosine in the diabetic placenta: evidence for oxidative stress

OBJECTIVE

To evaluate the presence of nitrotyrosine (NT) residues in placental villous tissue of diabetic pregnancies as an index of vascular damage linked to oxidative stress.

RESEARCH DESIGN AND METHODS

Villous tissue was collected and flash frozen after delivery from 10 class C and D IDDM patients (37.9+/-3.2 weeks) and 10 normotensive pregnant individuals (37.5+/-3.8 weeks). Serial sections of tissue were immunostained with specific antibodies to NT, endothelial nitric oxide synthase (eNOS), inducible nitric oxide synthase (iNOS), and manganese superoxide dismutase (MnSOD). Sections were scored for intensity of immunostaining (0-3) by three observers blinded to the identity of tissue.

RESULTS

All tissues demonstrated immunostaining for eNOS in both syncytiotrophoblast and stem villous vascular endothelium with no apparent differences between groups. Immunostaining for iNOS was seen in the villous stroma, but again was not different between the two groups. Significantly more intense NT staining was apparent in vascular endothelium and villous stroma (both P < 0.02) of diabetic placentas. The endothelium of large villous vessels of diabetic tissues also showed more intense immunostaining for MnSOD (P < 0.01).

CONCLUSIONS

In these diabetic pregnancies, we were unable to show increased eNOS, unlike previous findings in preeclamptic pregnancies. The presence of NT may indicate vascular damage in the diabetic placenta due to peroxynitrite action formed from increased synthesis/interaction of nitric oxide and superoxide. The apparently paradoxical increase in MnSOD expression may be an adaptive response to increased superoxide generation.

Puerperal thromboprophylaxis: comparison of the anti-Xa activity of enoxaparin and unfractionated heparin

Low molecular weight heparins are used extensively for thromboprophylaxis. The aim of this study was to compare the activity of the low molecular weight heparin, enoxaparin, 20 mg and 40 mg, given once per day with unfractionated heparin, 7500iu given twice per day, in terms of their anti-Xa activity in puerperal women following caesarean section and with an additional risk factor for venous thromboembolism. Seventeen women were randomised to receive one of the three treatments. The anti-Xa activity associated with each treatment was measured prior to treatment and at 2, 4, 6, 12 and 24 hours. The mean anti-Xa values of the groups receiving enoxaparin, 20 mg and 40 mg, were significantly higher than those of the group receiving unfractionated heparin. There was no difference between the two enoxaparin groups in terms of the anti-Xa activity profiles. This study suggests that the use of enoxaparin is superior to unfractionated heparin in terms of anti-Xa activity.

Circulating cell adhesion molecule concentrations in diabetic women during pregnancy

OBJECTIVE

To determine whether circulating concentrations of defined cell adhesion molecules, which are thought to reflect endothelial expression, are increased in insulin-dependent diabetic women during pregnancy.

METHODS

Pregnant diabetic women demonstrating good glycemic control and without major complications before pregnancy were studied at 8-12 (n = 15), 18 (n = 15), 28 (n = 16), 32 (n = 16), and 36 (n = 16) weeks' gestation. A subgroup of ten diabetic women was sampled longitudinally through all five gestational ages. The diabetic women were compared with healthy nondiabetic women sampled cross sectionally at 12 (n = 20), 28 (n = 19), and 36 (n = 19) weeks' gestation. Nonpregnant diabetic (n = 22) and nonpregnant nondiabetic women (n = 28) also were studied. Plasma concentrations of the cell adhesion molecules E-selectin, intercellular adhesion molecule-1 (ICAM-1), and vascular endothelial cell adhesion molecule-1 (VCAM-1) were measured by enzyme-linked immunosorbent assay.

RESULTS

Significantly higher median (range) concentrations of E-selectin (63.0 [20.2-107.0] ng/mL) and ICAM-1 (281.5 [171.6-778.4] ng/mL) but not VCAM-1 (459.7 [301.0-909.7] ng/mL) were found in nonpregnant diabetic women compared with nonpregnant nondiabetic women (43.5 [18.1-93.2], 243.6 [174.4-329.2], and 476.0 [253.8-929.4] ng/mL, respectively). During pregnancy these significant differences between diabetic and control groups were lost. The median (range) concentration of E-selectin (50.0 [21.2-96.3] ng/mL) was significantly lower in pregnant compared with nonpregnant diabetic women. The plasma concentrations of E-selectin and ICAM-1 did not change significantly with gestation in either diabetic or nondiabetic pregnant groups. Vascular endothelial cell adhesion molecule-1 concentration changed significantly with gestation in the diabetic pregnant group only.

CONCLUSION

Circulating concentrations of defined vascular cell adhesion molecules are not increased abnormally in diabetic women with good glycemic control during otherwise uncomplicated pregnancy.

Recognition of a Nocardia transvalensis complex by resistance to aminoglycosides, including amikacin, and PCR-restriction fragment length polymorphism analysis

Amikacin resistance, rare among nocardiae, was observed in 58 clinical isolates of nocardiae. All of these isolates hydrolyzed hypoxanthine, and 75 to 100% utilized citrate, D-galactose, and D-trehalose as sole carbon sources. Based on utilization of I-erythritol, D-glucitol, i-myo-inositol, D-mannitol, and ribitol and susceptibility to amoxicillin-clavulanic acid, the 58 isolates were separable into four groups. One group was negative for I-erythritol and ribitol and included all the isolates belonging to Nocardia asteroides complex antibiogram type IV. The remaining three groups were positive for I-erythritol and ribitol and were grouped within Nocardia transvalensis. The group that included the type strain was designated N. transvalensis sensu stricto, and the other two groups were designated new taxons 1 and 2. PCR-restriction fragment length polymorphism (RFLP) analysis of a 439-bp segment of the 65-kDa heat shock protein gene with XhoI and HinfI produced identical patterns for 53 (91%) and 58 (100%) isolates, respectively, and differentiated them from all other Nocardia taxa. NarI- and HaeIII-derived RFLP patterns clearly differentiated each of the four biochemically defined taxa. These four groups were also distinguishable by using the chromogenic substrates in Dade MicroScan test panels. By high-performance liquid chromatography, these isolates exhibited the same unique mycolic acid-ester elution patterns that differed from those of all other clinically significant nocardiae. Gas-liquid chromatographic analysis of fatty acids also produced similar patterns for all isolates that distinguished them from all other Nocardia taxa, but did not differentiate the four taxa within the complex. We propose the designation N. transvalensis complex for these four groups of nocardiae, pending further genetic evaluation.

Rapid identification of clinically significant species and taxa of aerobic actinomycetes, including Actinomadura, Gordona, Nocardia, Rhodococcus, Streptomyces, and Tsukamurella isolates, by DNA amplification and restriction endonuclease analysis

A previously described PCR-restriction fragment length polymorphism (RFLP) identification schema for Nocardia that used an amplified 439-bp segment (amplicon) of the 65-kDa heat shock protein gene was evaluated for potential use with isolates of all clinically significant aerobic actinomycetes. The study included 28 reference (American Type Culture Collection) strains and 198 clinical isolates belonging to 20 taxonomic groups. Of these 198 isolates, 188 could be differentiated by this PCR-RFLP method. Amplicons from all aerobic actinomycete isolates lacked BstEII recognition sites, thereby distinguishing them from those of mycobacteria that contain one or more such sites. Of 29 restriction endonucleases, MspI plus HinfI produced RFLP patterns that differentiated 16 of the 20 taxa. A single RFLP pattern was observed for 15 of 20 taxa that included 65% of phenotypically clustered isolates. Multiple patterns were seen with Gordona bronchialis, Nocardia asteroides complex type VI, Nocardia otitidiscaviarum, Nocardia transvalensis, and Streptomyces spp. Streptomyces RFLP patterns were the most heterogeneous (five patterns among 19 isolates), but exhibited a unique HinfI fragment of > 320 bp. RFLP patterns that matched those from type strains of Streptomyces albus, Streptomyces griseus, or Streptomyces somaliensis were obtained from 14 of 19 Streptomyces isolates. Only 10 of 28 isolates of N. otitidiscaviarum failed to yield satisfactory amplicons, while only 6 of 188 (3.2%) clinical isolates exhibited patterns that failed to match one of the 21 defined RFLP patterns. These studies extended the feasibility of using PCR-RFLP analysis as a rapid method for the identification of all clinically significant species and taxa of aerobic actinomycetes.

Analysis of the cbbXYZ operon in Rhodobacter sphaeroides

Three genes, cbbX, cbbY, and cbbZ were found downstream from the form I ribulose 1,5-bisphosphate carboxylase/oxygenase (RubisCO) genes of Rhodobacter sphaeroides. As in chemoautotrophic bacteria, cbbZ was shown to encode phosphoglycolate phosphatase (PGP), whereas the identities of cbbX and cbbY are not known. To determine the physiological function of the cbbXYZ gene products, we constructed R. sphaeroides strains in which the genes were inactivated and characterized the resultant mutant strains according to growth phenotype and levels of RubisCO and PGP. Only a mutation in cbbX resulted in a discernible phenotype, namely, impaired photoautotrophic growth. No PGP activity was observed in any of the mutants, suggesting that the three genes are transcriptionally linked. Studies with a spontaneous chemoautotrophic competent derivative of the CBBX mutant suggested that the cbbXYZ gene products are not essential for chemoautotrophic growth. PGP activity determined in the wild-type strain grown under a variety of growth conditions, and in various strains containing mutations in Calvin-Benson-Bassham cycle structural and regulatory genes, indicated that transcription of the cbb(I) operon influenced expression of the downstream cbbXYZ operon.

The molecular regulation of the reductive pentose phosphate pathway in Proteobacteria and Cyanobacteria

In phototrophic and chemoautotrophic proteobacteria, genes encoding enzymes of the Calvin-Benson-Bassham pathway of CO2 fixation are often found in clusters that are transcribed from a single promoter under control of the LysR-type transcriptional activator, CbbR. Mutations affecting CbbR prevent induction of cbb genes. Gel-retardation assays have demonstrated CbbR binding to putative regulatory regions of cbb operons, and in two cases, footprinting experiments have delimited the nucleotide sequence protected by CbbR. Fusion of cbb control sequences to reporter genes has allowed the regions required for promoter activity to be defined, and recent experiments indicate that the cbb regulon in Rhodobacter is controlled by a global two-component signal transduction system that also regulates other metabolic processes in this organism. Different ways of regulating CBB cycle enzymes that also have roles in heterotrophic metabolism have recently been discovered. In cyanobacteria, the genes of the CBB pathway are organized and regulated differently, and these oxygen-evolving phototrophic bacteria have evolved different strategies to control the assimilation of CO2.

DNA amplification and restriction endonuclease analysis for differentiation of 12 species and taxa of Nocardia, including recognition of four new taxa within the Nocardia asteroides complex

Nineteen reference and 156 clinical strains of the genus Nocardia belonging to 12 taxonomic groups were studied for restriction fragment length polymorphism (RFLP) by using an amplified 439-bp segment of the 65-kDa heat shock protein gene. Of 30 restriction endonucleases, digestion with MspI and then digestion with BsaHI produced RFLP band patterns which separated all 12 groups except N. asteroides type IV from 6 of 12 N. transvalensis isolates and N. carnea from the N. asteroides type VI isolates. Commonly encountered species such as N. nova, N. farcinica, N. brasiliensis sensu stricto, and N. otitidiscaviarum were easily separated. Each taxon resulted in a single RFLP band pattern that included > or = 96% of all biochemically grouped isolates for 9 of 12 taxa with MspI and for 8 of 12 taxa with BsaHI. With the use of both patterns, only 6 of 175 (3.4%) isolates failed to fit the biochemically defined group patterns. These studies provide the first evidence for the separate identities of four antibiogram-defined (but currently unnamed) groups within the N. asteroides complex (types I, II, IV, and VI) and the presence of two subgroups within N. transvalensis. They also provide genotypic evidence for the separate identities of N. nova and N. farcinica. The lack of BstEII recognition sites in amplicons obtained from nocardiae provides a simple and rapid method for the differentiation of nocardiae from mycobacteria. DNA amplification with RFLP analysis is the first rapid method that distinguishes all clinically significant taxa and recognized species within the genus Nocardia.

PCR amplification and restriction endonuclease analysis of a 65-kilodalton heat shock protein gene sequence for taxonomic separation of rapidly growing mycobacteria

A total of 129 reference and clinical strains of rapidly growing mycobacteria (RGM) belonging to 10 taxonomic groups were studied for restriction fragment length polymorphism patterns from a PCR-amplified 439-bp segment of the 65-kDa heat shock protein (HSP) gene. Of 24 endonucleases evaluated, restriction fragment length polymorphism patterns produced by HaeIII and BstEII and then by AciI and CfoI gave the best separation. Sixty percent of all RGM taxa studied were differentiated by HaeIII digests alone. Single unique patterns were observed with HaeIII and/or BstEII for Mycobacterium fortuitum (100%), M. chelonae (94%), M. abscessus (96%), M. smegmatis (100%), M. mucogenicum (formerly the M. chelonae-like organism) (100%), and the sorbitol-negative third biovariant of M. fortuitum (100%). Evidence is presented in support of two subgroups within M. peregrinum, M. smegmatis, and the unnamed third biovariant of M. fortuitum (sorbitol positive and sorbitol negative). PCR-based technology provides a rapid, accurate system for the identification of clinically important species of RGM which should be particularly useful for reference laboratories.

A case of recurrent typhoid fever in the United States: importance of the grandmother connection and the use of large restriction fragment pattern analysis of genomic DNA for strain comparison

An 8-year old girl was infected for a second time with Salmonella typhi by contact with her grandmother, a known typhoid carrier. The S. typhi from both patient and grandmother had closely related genomic pulsed field gel electrophoresis patterns that differed from epidemiologically unrelated strains. The girl responded well to a 14-day course of oral trimethoprimsulfamethoxazole. The grandmother was treated successfully with a 28-day regimen of oral ciprofloxacin. Typhoid fever remains an endemic disease in the United States, largely because of recognized chronic stool carriers. Most of these carriers had typhoid in the preantibiotic era and remain potential sources of disease when they provide meals for others, not uncommonly grandchildren. The importance of this "grandmother" connection to endemic typhoid fever is reviewed, as is the potential use of pulsed field gel electrophoresis pattern analysis for comparison of strains of S. typhi.

Identification of epitopes and affinity purification of thyroid stimulating auto-antibodies using synthetic human TSH receptor peptides

We prepared a series of overlapping peptides (29 in total, 20 amino acids each) containing the sequence of the entire extracellular domain of the human TSH receptor. Three peptides (181-200, 376-394, and EC3 (629-639)) bound IgG from patients with Graves' disease in an enzyme linked immunoassay. Peptide 181-200 bound IgG from 9 of 10, EC3 from 8 of 10, and 376-394 from 6 of 10 patients respectively, compared to 0 of 9 controls. We affinity purified TSHr auto-antibodies from four Graves' patients using the three above noted peptides bound to epoxy-activated sepharose. Thyroid stimulating activity was enriched in the bound fraction from at least two of the three peptide affinity columns in each of the four patients, although the pattern of affinity enrichment differed between patients. One patient was found to possess a combination of stimulatory and inhibitory TSHr antibodies and, after affinity purification, the anti-376-394 and anti-EC3 fractions were enriched in stimulatory activity, suggesting that those regions of the receptor were epitopes for stimulatory antibodies. However, affinity purification against peptide 181-200 produced an IgG preparation that was not stimulatory, but was a potent thyroid inhibitor. Thus, we have not only partially purified TSHr auto-antibodies, but also successfully separated stimulatory and inhibitory antibodies from a single patient using combination TSHr peptide affinity.

Nucleotide sequence and functional analysis of cbbR, a positive regulator of the Calvin cycle operons of Rhodobacter sphaeroides

Structural genes encoding Calvin cycle enzymes in Rhodobacter sphaeroides are duplicated and organized within two physically distinct transcriptional units, the form I and form II cbb operons. Nucleotide sequence determination of the region upstream of the form I operon revealed a divergently transcribed open reading frame, cbbR, that showed significant similarity to the LysR family of transcriptional regulatory proteins. Mutants containing an insertionally inactivated cbbR gene were impaired in photoheterotrophic growth and completely unable to grow photolithoautotrophically with CO2 as the sole carbon source. In the cbbR strain, expression of genes within the form I operon was completely abolished and that of the form II operon was reduced to about 30% of the wild-type level. The cloned cbbR gene complemented the mutant for wild-type growth characteristics, and normal levels of ribulose 1,5-bisphosphate carboxylase/oxygenase (RubisCO) were observed. However, rocket immunoelectrophoresis revealed that the wild-type level of RubisCO was due to overexpression of the form II enzyme, whereas expression of the form I RubisCO was 10% of that of the wild-type strain. The cbbR insertional inactivation did not appear to affect aerobic expression of either CO2 fixation operon, but preliminary evidence suggests that the constitutive expression of the form II operon observed in the cbbR strain may be subject to repression during aerobic growth.

The Rubisco activase (rca) gene is located downstream from rbcS in Anabaena sp. strain CA and is detected in other Anabaena/Nostoc strains

A gene encoding ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) activase (rca) was found downstream from the rbcLrbcS operon in the heterocystous cyanobacterium Anabaena sp. strain CA. Two unknown open reading frames were shown to be located between rbcS and rca in strain CA and all the genes, rbcLrbcS, ORF1, ORF2, and rca were in the same transcriptional orientation. The deduced amino acid sequence of the Anabaena Rubisco activase showed both similarities and differences to the plant enzyme with considerable differences at the carboxy and amino termini. Proposed ATP-binding sites were conserved in the cyanobacterial protein. Recombinant cyanobacterial Rubisco activase, however, reacted with antisera to spinach Rubisco activase. Hybridization studies, using the Anabaena sp. strain CA rca gene as a heterologous probe, detected homologous sequences in heterocystous Anabaena/Nostoc strains but not in unicellular or nonheterocystous filamentous cyanobacteria, suggestive of a close evolutionary relationship of chloroplasts and heterocystous cyanobacteria.

Uniform designation for genes of the Calvin-Benson-Bassham reductive pentose phosphate pathway of bacteria

Structural and regulatory genes encoding enzymes and proteins of the reductive pentose phosphate pathway have been isolated from a number of bacteria recently. In the phototroph Rhodobacter sphaeroides, and in two chemoautotrophic bacteria, Alcaligenes eutrophus and Xanthobacter flavus, these genes have been found in distinct operons. However, in these three organisms and in other bacteria where certain of these genes have been discovered, a uniform nomenclature to designate these genes has been lacking. This report represents an effort to provide uniformity to the designation of these genes from all bacteria.

Identification, expression, and deduced primary structure of transketolase and other enzymes encoded within the form II CO2 fixation operon of Rhodobacter sphaeroides

Previous studies had indicated that the form II or B cluster of CO2 fixation structural genes is part of a large operon in Rhodobacter sphaeroides (Gibson, J. L., Chen, J.-H., Tower, P. A., and Tabita, F. R. (1990) Biochemistry 29, 8085-8093). In this investigation, we have sequenced the DNA between the prkB and rbpL genes and provide evidence for three distinct open reading frames which encode additional structural genes of the Calvin reductive pentose phosphate pathway; these genes encode the enzymes transketolase, glyceraldehyde phosphate dehydrogenase, and aldolase. Noteworthy is transketolase, which may be expressed to high levels in Escherichia coli. This study thus represents the initial description of the primary structure of bacterial transketolase, a key enzyme of the reductive and the oxidative pentose phosphate pathways. Each of the genes are separated by short stretches of intergenic sequence, consistent with earlier evidence which suggested that these genes are cotranscribed and part of a large operon controlled by sequences upstream from fbpB.

Nucleotide sequence, transcriptional analysis, and expression of genes encoded within the form I CO2 fixation operon of Rhodobacter sphaeroides

In Rhodobacter sphaeroides, many of the structural genes encoding enzymes of the Calvin cycle are duplicated and grouped within two separate clusters. In this study, the nucleotide sequence of a 5627-base pair region of DNA that contains the form I Calvin cycle gene cluster has been determined. The five open reading frames are arranged in the order, fbpA prkA cfxA rbcL rbcS and are tightly linked and oriented in the same direction. The results of insertional mutagenesis studies suggest the genes are organized within an operon. Consistent with this proposal, the cfxA gene has been tentatively identified as a gene encoding the Calvin cycle enzyme, aldolase. Measurement of the activities of various Calvin cycle enzymes in the insertion mutants showed that inactivation of genes within one CO2 fixation cluster affected expression of genes within the second cluster, revealing a complex regulatory network.

Extreme ultraviolet transmission of a synthetic diamond thin film

The transmission of a thin film of synthetic diamond was measured at various wavelengths in the extreme ultraviolet. The measurements agree with a prediction based on published carbon attenuation coefficients assuming the density of natural diamond. A betterfit to the data results when an additional approximately 200-A layer of silicon is included in the model. It is believed that this silicon layer exists as silicon carbide.

Rat cholesterol side-chain cleavage cytochrome P-450 (P-450scc) gene. Structure and regulation by cAMP in vitro

The entire rat P-450scc gene has been cloned, positions/sequences of the exon-intron boundaries (I-IX) are described and 940 base pairs (bp) of 5'-flanking DNA have been sequenced, compared to mouse, bovine and human genes, and analyzed by functional assays. Primer extension analysis mapped the transcription start site 32 bp upstream of the initiator methionine codon. The rat P-450scc promoter was ligated to the human growth hormone (GH) gene yielding p-940RsccGH. This rat P-450scc fusion gene and a mouse gene (p-1500MsccGH) were transiently transfected into primary cultures of rat granulosa cells and Y1 adrenal cells. In the Y1 cells primer extension analysis showed that the rat P-450sccGH gene was expressed at lower basal levels than that of the mouse gene but showed greater stimulation (4-8-fold) in response to 8-bromo-cyclic AMP than the mouse (3-4-fold). Similar results were obtained when the fusion genes were transfected into primary cultures of rat granulosa cells and production of GH was measured in the media of the cells stimulated with forskolin. Furthermore, we document that gonadotropins (follicle-stimulating hormone/luteinizing hormone) can induce luteinization of granulosa cells in vitro, that this process is associated with constitutive maintenance of P-450scc mRNA in the absence of hormones/cAMP, that these events associated with luteinization are differentiation-stage specific and occur only in granulosa cells of preovulatory follicles but not in small antral follicles, that the process can be inhibited by cycloheximide if the protein synthesis inhibitor is present during the first 6 h of exposure to luteinizing hormone but not if added for short durations (3-5 h) later, and that once luteinization is induced P-450scc mRNA expression and progesterone biosynthesis are not strictly dependent on cAMP. Thus, the P-450scc gene is regulated by both cAMP-dependent and cAMP-independent mechanisms, each of which are associated with a specific stage of granulosa cell differentiation. The DNA domains involved in regulating these two diverse processes remain to be determined. Although there was remarkable sequence homology among rat, mouse, bovine, and human genes within 70 bp of the transcriptional start site, no other sequence similarities revealed conserved functional domains among the four genes. Although some cAMP-responsive element-like sequences are present in the rat gene, these were not conserved in the other species; including the mouse which showed high sequence homology with the rat throughout 900 bp of 5'-flanking DNA. Thus, the cAMP domains specific to this and other steroidogenic genes remain to be clearly identified.

Recent studies on the molecular biology and biochemistry of CO2 fixation in phototrophic bacteria

Rhodobacter sphaeroides was found to contain two clusters of chromosomally encoded CO2 fixation structural genes. Recent studies indicate that genes within each cluster are cotranscribed, suggesting that there is a single long transcript for each cluster. All of the genes have been sequenced, homologies noted, specific mutations obtained, and interesting upstream regulatory sequences found. Site-directed mutagenesis studies of the Anacystis rbcS has begun to provide information relative to RubisCO structure and function. In addition, RubisCO-negative strains of photosynthetic bacteria have been constructed to screen for altered RubisCO sequences.

The form II fructose 1,6-bisphosphatase and phosphoribulokinase genes form part of a large operon in Rhodobacter sphaeroides: primary structure and insertional mutagenesis analysis

Fructose 1,6-bisphosphatase (FBPase) and phosphoribulokinase (PRK) are two key enzymes of the reductive pentose phosphate pathway or Calvin cycle of photosynthetic carbon dioxide assimilation. Early studies had indicated that the properties of enzymes isolated from photosynthetic bacteria were clearly distinct from those of enzymes obtained from the chloroplasts of higher plants [for a review, see Tabita (1988)]. The eucaryotic enzymes, which are light activated by the thioredoxin/ferredoxin system (Buchanan, 1980), were each shown to contain a putative regulatory amino acid sequence (Marcus et al., 1988; Porter et al., 1988). The enzymes from photosynthetic bacteria are not controlled by the thioredoxin/ferredoxin system but exhibit complex kinetic properties and, in the case of PRK, there is an absolute requirement of NADH for activity. In the photosynthetic bacterium Rhodobacter sphaeroides, the structural genes of the Calvin cycle, including the genes that encode FBPase (fbp) and PRK (prk), are found in two distinct clusters, and the fbp and prk genes are closely associated in each cluster. In the present investigation, we have determined the nucleotide sequence of the fbpB and prkB genes of the form II cluster and have compared the deduced amino acid sequences to previously determined sequences of light-activated enzymes from higher plants and from other eucaryotic and procaryotic sources. In the case of FBPase, there are several regions that are conserved in the R. sphaeroides enzymes, including a protease-sensitive area located in a region equivalent to residues 51-71 of mammalian FBPase.(ABSTRACT TRUNCATED AT 250 WORDS)

A single-blind, placebo-controlled study of glycosaminoglycan-peptide complex ('Rumalon') in patients with osteoarthritis of the hip or knee

A randomized, single-blind, placebo-controlled trial was carried out in 62 patients (30 with osteoarthritis of the hip, 32 with osteoarthritis of the knee) to examine the efficacy of glycosaminoglycan-peptide complex in the treatment of osteoarthritis. Patients received 8-week courses of trial medication, each consisting of intramuscular injections of 3 x 2 ml ampoules per week, alternating with 8-week periods free of trial medication, in addition to conventional drug therapy and physiotherapy, as required. After 2-years' treatment, glycosaminoglycan-peptide-treated patients showed significant improvements, as compared with placebo, in relation to night pain, pain during the day, joint mobility and walking ability. Similar results were seen with both osteoarthritis of the hip and knee. In osteoarthritis of the knee it was also possible to assess joint swelling and this also showed a significant improvement. There were no significant changes in range of joint movement except for a significant decrease in active flexion in the patients with osteoarthritis of the knee treated with placebo. In contrast with many anti-osteoarthritic drugs, glycosaminoglycan-peptide complex was very well tolerated. These results suggest that glycosaminoglycan-peptide complex may be a valuable alternative form of long-term therapy for patients with osteoarthritis.

Localization and mapping of CO2 fixation genes within two gene clusters in Rhodobacter sphaeroides

Two fructose 1,6-bisphosphatase structural genes (fbpA and fbpB) have been identified within two unlinked gene clusters that were previously shown to contain the Rhodobacter sphaeroides sequences that code for form I and form II ribulose 1,5-bisphosphate carboxylase-oxygenase and phosphoribulokinase. The fbpA and fbpB genes were localized to a region immediately upstream from the corresponding prkA and prkB sequences and were found to be transcribed in the same direction as the phosphoribulokinase and ribulose 1,5-bisphosphate carboxylase-oxygenase genes based on inducible expression of fructose 1,6-bisphosphatase activity directed by the lac promoter. A recombinant plasmid was constructed that contained the tandem fbpA and prkA genes inserted downstream from the lac promoter in plasmid pUC18. Both gene products were expressed in Escherichia coli upon induction of transcription with isopropyl beta-D-thiogalactoside, demonstrating that the two genes can be cotranscribed. A Zymomonas mobilis glyceraldehyde 3-phosphate-dehydrogenase gene (gap) hybridized to a DNA sequence located approximately 1 kilobase upstream from the form II ribulose 1,5-bisphosphate carboxylase-oxygenase gene. Although no corresponding gap sequence was found within the form I gene cluster, an additional region of homology was detected immediately upstream from the sequences that encode the form I and form II ribulose 1,5-bisphosphate carboxylase-oxygenases.

Organization of phosphoribulokinase and ribulose bisphosphate carboxylase/oxygenase genes in Rhodopseudomonas (Rhodobacter) sphaeroides

A heterologous phosphoribulokinase (PRK) gene probe was used to analyze two recombinant plasmids isolated from a Rhodopseudomonas (Rhodobacter) sphaeroides gene library. These plasmids were previously shown to carry the genes for form I and form II ribulose 1,5-bisphosphate carboxylase/oxygenase (RuBPC/O). Southern blot hybridization analysis indicated that there were two PRK genes linked to the RuBPC/O coding sequences. Restriction mapping showed the arrangement of the duplicate sets of PRK and RuBPC/O to be distinct. Subcloning of the hybridizing PRK sequences downstream of the lac promoter of pUC8 allowed expression of the two PRK enzymes in Escherichia coli. Analysis of the purified proteins by sodium dodecyl sulfate-slab gel electrophoresis revealed polypeptides with molecular weights of 32,000 and 34,000 corresponding to the form I and form II PRKs, respectively. Preliminary experiments on sensitivity to NADH regulation suggested that the two PRK enzymes differ in catalytic properties.

Isolation of the Rhodopseudomonas sphaeroides form I ribulose 1,5-bisphosphate carboxylase/oxygenase large and small subunit genes and expression of the active hexadecameric enzyme in Escherichia coli

A library of cloned Rhodopseudomonas sphaeroides DNA was screened by colony hybridization for form I ribulose 1,5-bisphosphate carboxylase/oxygenase (RuBPC/O) sequences using heterologous RuBPC/O probes. A recombinant plasmid was identified that hybridized to both the Anacystis nidulans and the R. sphaeroides form II RuBPC/O genes. Subcloning of a hybridizing 4-kb SmaI fragment allowed expression of active enzyme in Escherichia coli that was identical to form I RuBPC/O based on polyacrylamide gel electrophoresis and Western immunoblot analysis.

Structural differences in the catalytic subunits of form I and form II ribulose 1,5-bisphosphate carboxylase/oxygenase from Rhodopseudomonas sphaeroides

There are significant differences in the large subunits of form I and form II ribulose 1,5-bisphosphate carboxylase/oxygenase isolated from Rhodopseudomonas sphaeroides. Two-dimensional peptide mapping of carboxymethylated large subunits clearly indicates that there are differences in the primary structure of the two proteins. These results are supported by limited proteolysis with three different proteases and by subsequent analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. These data, in conjunction with immunological studies and investigations on the regulation of the two enzymes, support the conclusion that the large subunits of form I and form II ribulose 1,5-bisphosphate carboxylase/oxygenase may be different gene products.

Marital relationships, evaluations of spouse and self, and anxiety

Questionaire data were gathered from 164 married couples to test hypotheses that husbands' and wives' anxiety levels will be low to the extent that: (a)they share decision-making power, share household role responsibilities, and express high maritial solidarity; and (b) they hold positive evaluations of one another, perceive positive reactions from one another, and show positive self-evaluations. The first hypothesis was supported only for solidarity. The second hypothesis received strong support for husbands and wives. For wives, solidarity was the strongest predictor of anxiety, while self-evaluation was the most important factor for husbands.

Activation of ribulose 1,5-bisphosphate carboxylase from Rhodopseudomonas sphaeroides: probable role of the small subunit

The activation properties of the form I and form II ribulose 1,5-bisphosphate carboxylases from Rhodopseudomonas sphaeroides were examined. Both enzymes have a requirement of Mg2+ for optimal activity. Mn2+, Ni2+, and Co2+ can also support activity of the form I enzyme, whereas only Mn2+ can substitute for Mg2+ with the form II enzyme. The effect of different preincubations on the carboxylase reaction was also examined. Both enzymes exhibited a lag when preincubated with other than Mg2+ and CO2 before assay, but the lag was much more pronounced and the rate of the reaction was slower with the form I enzyme under these conditions. Activation of the form I carboxylase By Mg2+ and CO2 occurred more rapidly than that of the form II enzyme. The results obtained with the two distinct forms of carboxylase from R. sphaeroides, as well as studies with the spinach and Rhodospirillum rubrum enzymes, thus indicate that the presence of the small subunit affects the rate of activation by Mg2+ and CO2 as well as the rate of reactivation of ribulose bisphosphate-inactivated enzyme.

Isolation and preliminary characterization of two forms of ribulose 1,5-bisphosphate carboxylase from Rhodopseudomonas capsulata

The presence of two distinct forms of ribulose 1,5-bisphosphate carboxylase has been demonstrated in extracts of Rhodopseudomonas capsulata, similar to the form I (peak I) and form II (peak II) carboxylases previously described from R. sphaeroides (J. Gibson and F. R. Tabita, J. Biol. Chem 252:943-949, 1977). The two activities, separated by diethylaminoethyl-cellulose chromatography, were shown to be of different molecular size after assay on polyacrylamide gels. The higher-molecular-weight carboxylase from R. capsulata was designated form I-C, whereas the smaller enzyme was designated form II-C. Catalytic studies revealed significant differences between the two enzymes in response to pH and the effector 6-phosphogluconate. Immunological studies with antisera directed against the carboxylases from R. sphaeroides demonstrated antigenic differences between the two R. capsulata enzymes; cross-reactivity was observed only between R. sphaeroides anti-form II serum and the corresponding R. capsulata enzyme, form II-C.

Different molecular forms of D-ribulose-1,5-bisphosphate carboxylase from Rhodopseudomonas sphaeroides

Ribulose-1,5-bisphosphate (Rbu-P2) carboxylase isolated from Rhodopseudomonas sphaeroides 2.4.1.Ga was separated into two different forms by DEAE-cellulose column chromatography. Both forms, designated Peak I and Peak II have been purified to homogeneity by the criterion of polyacrylamide disc-gel electrophoresis. The Peak I carboxylase has a molecular weight of 550,000, while the Peak II carboxylase is a smaller protein having a molecular weight of approximately 360,000. Sodium dodecyl sulfate electrophoresis revealed a large subunit for both enzymes which migrates similarly to the large subunit of spinach Rbu-P2 carboxylase. The Peak I enzyme also exhibited a small subunit having a molecular weight of 11,000. No evidence for a smaller polypeptide was found associated with the Peak II enzyme. Antisera prepared against the Peak I enzyme inhibited Peak I enzymatic activity, but had no effect on the activity of the Peak II enzyme. The two enzymes exhibited marked differences in catalytic properties. The Peak I enzyme exhibits optimal activity at pH 8.0 and is inhibited by low concentrations of 6-phosphogluconate, while the Peak II enzyme has a pH optimum of 7.2 and is relatively insensitive to 6-phosphogluconate.

Carbon dioxide assimilation in blue-green algae: initial studies on the structure of ribulose 1,5-bisphosphate carboxylase

D-Ribulose 1,5-bisphosphate carboxylase was purified from the blue-green alga Anabaena cylindrica (Lemm) by procedures involving acid precipitation, ammonium sulfate fractionation, and Sephadex G-200 gel filtration. The enzyme was homogeneous by the criterion of polyacrylamide disc gel electrophoresis and was a multimer of a single-size polypeptide chain of 54,000 daltons. The carboxylases from four species of blue-green algae (Anabaena, Nostoc strain MAC, Agmenellum quadruplicatum strain PR-6, and Anacystis nidulans strain TX20) were closely similar in molecular size, since enzyme activity was eluted at the same volume after sucrose gradient centrifugation. Further analysis by gel filtration indicated that the four blue-green algal carboxylases were nearly identical in molecular weight, ranging from 449 to 453,000. The amino acid composition of the Anabaena carboxylase was determined and was found to resemble closely the composition of the large subunit from eukaryotic photosynthetic organisms.