Structure of the WYL-domain containing transcription activator, DriD, in complex with ssDNA effector and DNA target site

Transcription regulators play central roles in orchestrating responses to changing environmental conditions. Recently the Caulobacter crescentus transcription activator DriD, which belongs to the newly defined WYL-domain family, was shown to regulate DNA damage responses independent of the canonical SOS pathway. However, the molecular mechanisms by which DriD and other WYL-regulators sense environmental signals and recognize DNA are not well understood. We showed DriD DNA-binding is triggered by its interaction with ssDNA, which is produced during DNA damage. Here we describe the structure of the full-length C. crescentus DriD bound to both target DNA and effector ssDNA. DriD consists of an N-terminal winged-HTH (wHTH) domain, linker region, three-helix bundle, WYL-domain and C-terminal WCX-dimer domain. Strikingly, DriD binds DNA using a novel, asymmetric DNA-binding mechanism that results from different conformations adopted by the linker. Although the linker does not touch DNA, our data show that contacts it makes with the wHTH are key for specific DNA binding. The structure indicates how ssDNA-effector binding to the WYL-domain impacts wHTH DNA binding. In conclusion, we present the first structure of a WYL-activator bound to both effector and target DNA. The structure unveils a unique, asymmetric DNA binding mode that is likely conserved among WYL-activators.

M. mazei glutamine synthetase and glutamine synthetase-GlnK1 structures reveal enzyme regulation by oligomer modulation

Glutamine synthetases (GS) play central roles in cellular nitrogen assimilation. Although GS active-site formation requires the oligomerization of just two GS subunits, all GS form large, multi-oligomeric machines. Here we describe a structural dissection of the archaeal Methanosarcina mazei (Mm) GS and its regulation. We show that Mm GS forms unstable dodecamers. Strikingly, we show this Mm GS oligomerization property is leveraged for a unique mode of regulation whereby labile Mm GS hexamers are stabilized by binding the nitrogen regulatory protein, GlnK1. Our GS-GlnK1 structure shows that GlnK1 functions as molecular glue to affix GS hexamers together, stabilizing formation of GS active-sites. These data, therefore, reveal the structural basis for a unique form of enzyme regulation by oligomer modulation.

Structures of the DarR transcription regulator reveal unique modes of second messenger and DNA binding

The mycobacterial repressor, DarR, a TetR family regulator (TFR), was the first transcription regulator shown to bind c-di-AMP. However, the molecular basis for this interaction and the mechanism involved in DNA binding by DarR remain unknown. Here we describe DarR-c-di-AMP and DarR-DNA structures and complementary biochemical assays. The DarR-c-di-AMP structure reveals a unique effector binding site for a TFR, located between DarR dimer subunits. Strikingly, we show this motif also binds cAMP. The location of the adenine nucleotide binding site between subunits suggests this interaction may facilitate dimerization and hence DNA binding. Indeed, biochemical assays show cAMP enhances DarR DNA binding. Finally, DarR-DNA structures reveal a distinct TFR DNA-binding mechanism involving two interacting dimers on the DNA. Thus, the combined data unveil a newly described second messenger binding motif and DNA binding mode for this important family of regulators.

Structure of the T. brucei kinetoplastid RNA editing substrate-binding complex core component, RESC5

Kinetoplastid protists such as Trypanosoma brucei undergo an unusual process of mitochondrial uridine (U) insertion and deletion editing termed kinetoplastid RNA editing (kRNA editing). This extensive form of editing, which is mediated by guide RNAs (gRNAs), can involve the insertion of hundreds of Us and deletion of tens of Us to form a functional mitochondrial mRNA transcript. kRNA editing is catalyzed by the 20 S editosome/RECC. However, gRNA directed, processive editing requires the RNA editing substrate binding complex (RESC), which is comprised of 6 core proteins, RESC1-RESC6. To date there are no structures of RESC proteins or complexes and because RESC proteins show no homology to proteins of known structure, their molecular architecture remains unknown. RESC5 is a key core component in forming the foundation of the RESC complex. To gain insight into the RESC5 protein we performed biochemical and structural studies. We show that RESC5 is monomeric and we report the T. brucei RESC5 crystal structure to 1.95 Å. RESC5 harbors a dimethylarginine dimethylaminohydrolase-like (DDAH) fold. DDAH enzymes hydrolyze methylated arginine residues produced during protein degradation. However, RESC5 is missing two key catalytic DDAH residues and does bind DDAH substrate or product. Implications of the fold for RESC5 function are discussed. This structure provides the first structural view of an RESC protein.

A cold wave of winter 2021 in central South America: characteristics and impacts

During the austral winter (June-August) of 2021, the meteorological services of Brazil, Argentina, Peru, Paraguay, Bolivia, and Chile all issued forecasts for unusually cold conditions. Record-low minimum temperatures and cold spells were documented, including one strong cold wave episode that affected 5 countries. In this study, we define a cold wave as a period in which daily maximum and minimum air temperatures are below the corresponding climatological 10th percentile for three or more consecutive days. The intense cold wave event in the last week of June, 2021, resulted in record-breaking minimum daily temperatures in several places in central South America and Chile. Several locations had temperatures about 10 °C below average, central South America had freezing conditions, and southern Brazil even saw snow. The cold air surge was characterized by an intense upper-air trough located close to 35° S and 70° W. The southerly flow to the west of this trough brought very cold air northward into subtropical and tropical South America. A northward flow between the lower-level cyclonic and anticyclonic perturbations caused the intense southerly flow between the upper-level ridge and trough. This condition facilitated the inflow of near-surface cold air from southern Argentina into southeastern Brazil and tropical South America east of the Andes. In the city of São Paulo, the cold wave caused the death of 13 homeless people from hypothermia. Frost and snow across southern and southeastern Brazil caused significant damage to coffee, sugarcane, oranges, grapes, and other fruit and vegetable crops. Wine and coffee production fell, the latter by 30%, and prices of food and commodities in the region rose.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00382-023-06701-1.

Allosteric regulation of glycogen breakdown by the second messenger cyclic di-GMP

Streptomyces are our principal source of antibiotics, which they generate concomitant with a complex developmental transition from vegetative hyphae to spores. c-di-GMP acts as a linchpin in this transition by binding and regulating the key developmental regulators, BldD and WhiG. Here we show that c-di-GMP also binds the glycogen-debranching-enzyme, GlgX, uncovering a direct link between c-di-GMP and glycogen metabolism in bacteria. Further, we show c-di-GMP binding is required for GlgX activity. We describe structures of apo and c-di-GMP-bound GlgX and, strikingly, their comparison shows c-di-GMP induces long-range conformational changes, reorganizing the catalytic pocket to an active state. Glycogen is an important glucose storage compound that enables animals to cope with starvation and stress. Our in vivo studies reveal the important biological role of GlgX in Streptomyces glucose availability control. Overall, we identify a function of c-di-GMP in controlling energy storage metabolism in bacteria, which is widespread in Actinobacteria.

Molecular dissection of the glutamine synthetase-GlnR nitrogen regulatory circuitry in Gram-positive bacteria

How bacteria sense and respond to nitrogen levels are central questions in microbial physiology. In Gram-positive bacteria, nitrogen homeostasis is controlled by an operon encoding glutamine synthetase (GS), a dodecameric machine that assimilates ammonium into glutamine, and the GlnR repressor. GlnR detects nitrogen excess indirectly by binding glutamine-feedback-inhibited-GS (FBI-GS), which activates its transcription-repression function. The molecular mechanisms behind this regulatory circuitry, however, are unknown. Here we describe biochemical and structural analyses of GS and FBI-GS-GlnR complexes from pathogenic and non-pathogenic Gram-positive bacteria. The structures show FBI-GS binds the GlnR C-terminal domain within its active-site cavity, juxtaposing two GlnR monomers to form a DNA-binding-competent GlnR dimer. The FBI-GS-GlnR interaction stabilizes the inactive GS conformation. Strikingly, this interaction also favors a remarkable dodecamer to tetradecamer transition in some GS, breaking the paradigm that all bacterial GS are dodecamers. These data thus unveil unique structural mechanisms of transcription and enzymatic regulation.

ssDNA is an allosteric regulator of the C. crescentus SOS-independent DNA damage response transcription activator, DriD

DNA damage repair systems are critical for genomic integrity. However, they must be coordinated with DNA replication and cell division to ensure accurate genomic transmission. In most bacteria, this coordination is mediated by the SOS response through LexA, which triggers a halt in cell division until repair is completed. Recently, an SOS-independent damage response system was revealed in Caulobacter crescentus. This pathway is controlled by the transcription activator, DriD, but how DriD senses and signals DNA damage is unknown. To address this question, we performed biochemical, cellular, and structural studies. We show that DriD binds a specific promoter DNA site via its N-terminal HTH domain to activate transcription of genes, including the cell division inhibitor didA A structure of the C-terminal portion of DriD revealed a WYL motif domain linked to a WCX dimerization domain. Strikingly, we found that DriD binds ssDNA between the WYL and WCX domains. Comparison of apo and ssDNA-bound DriD structures reveals that ssDNA binding orders and orients the DriD domains, indicating a mechanism for ssDNA-mediated operator DNA binding activation. Biochemical and in vivo studies support the structural model. Our data thus reveal the molecular mechanism underpinning an SOS-independent DNA damage repair pathway.

DNA mismatches reveal conformational penalties in protein-DNA recognition

Transcription factors recognize specific genomic sequences to regulate complex gene-expression programs. Although it is well-established that transcription factors bind to specific DNA sequences using a combination of base readout and shape recognition, some fundamental aspects of protein-DNA binding remain poorly understood1,2. Many DNA-binding proteins induce changes in the structure of the DNA outside the intrinsic B-DNA envelope. However, how the energetic cost that is associated with distorting the DNA contributes to recognition has proven difficult to study, because the distorted DNA exists in low abundance in the unbound ensemble3-9. Here we use a high-throughput assay that we term SaMBA (saturation mismatch-binding assay) to investigate the role of DNA conformational penalties in transcription factor-DNA recognition. In SaMBA, mismatched base pairs are introduced to pre-induce structural distortions in the DNA that are much larger than those induced by changes in the Watson-Crick sequence. Notably, approximately 10% of mismatches increased transcription factor binding, and for each of the 22 transcription factors that were examined, at least one mismatch was found that increased the binding affinity. Mismatches also converted non-specific sites into high-affinity sites, and high-affinity sites into 'super sites' that exhibit stronger affinity than any known canonical binding site. Determination of high-resolution X-ray structures, combined with nuclear magnetic resonance measurements and structural analyses, showed that many of the DNA mismatches that increase binding induce distortions that are similar to those induced by protein binding-thus prepaying some of the energetic cost incurred from deforming the DNA. Our work indicates that conformational penalties are a major determinant of protein-DNA recognition, and reveals mechanisms by which mismatches can recruit transcription factors and thus modulate replication and repair activities in the cell10,11.

The Gut of Healthy Infants in the Community as a Reservoir of ESBL and Carbapenemase-Producing Bacteria

The recent rapid rise of multi-drug resistant Enterobacteriaceae (MDR-E) is threatening the treatment of common infectious diseases. Infections with such strains lead to increased mortality and morbidity. Using a cross-sectional study, we aimed to estimate the prevalence of gut colonization with extended spectrum beta-lactamase (ESBL) producing Enterobacteriaceae among healthy infants born in Pakistan, a setting with high incidence of MDR-E infections. Stool samples were collected from 104 healthy infants between the ages of 5 and 7 months. Enterobacteriaceae isolates were screened for resistance against several antimicrobial classes. Presence of ESBL and carbapenemase genes was determined using multiplex PCR. Sequence types were assigned to individual strains by multi-locus sequence typing. Phylogenetic analysis of Escherichia coli was done using the triplex PCR method. Forty-three percent of the infants were positive for ESBL-producing Enterobacteriaceae, the majority of which were E. coli. We identified several different ESBL E. coli sequence types most of which belonged to the phylogenetic group B2 (23%) or D (73%). The widespread colonization of infants in a developing country with ESBL-producing Enterobacteriaceae is concerning. The multiple sequence types and reported non-human sources support that multiple non-epidemic MDR lineages are circulating in Pakistan with healthy infants as a common reservoir.

Infrared Spectroscopic Observation of a G-C+ Hoogsteen Base Pair in the DNA:TATA-Box Binding Protein Complex Under Solution Conditions

Hoogsteen DNA base pairs (bps) are an alternative base pairing to canonical Watson-Crick bps and are thought to play important biochemical roles. Hoogsteen bps have been reported in a handful of X-ray structures of protein-DNA complexes. However, there are several examples of Hoogsteen bps in crystal structures that form Watson-Crick bps when examined under solution conditions. Furthermore, Hoogsteen bps can sometimes be difficult to resolve in DNA:protein complexes by X-ray crystallography due to ambiguous electron density and by solution-state NMR spectroscopy due to size limitations. Here, using infrared spectroscopy, we report the first direct solution-state observation of a Hoogsteen (G-C⁺ ) bp in a DNA:protein complex under solution conditions with specific application to DNA-bound TATA-box binding protein. These results support a previous assignment of a G-C⁺ Hoogsteen bp in the complex, and indicate that Hoogsteen bps do indeed exist under solution conditions in DNA:protein complexes.

Clinical and epidemiological features of myasthenia gravis in Chilean population

OBJECTIVE

To provide an estimated prevalence and describe the clinical features of myasthenia gravis (MG) in Chile.

METHOD

We carried out (i) a prevalence study of MG using the capture-recapture method and the hospital register of pyridostigmine prescription in South-East Santiago (ii) a nationwide survey of MG patients.

RESULTS

Prevalence in adults in South-East Santiago was estimated to be 8.36/100 000 inhabitants (CI: 95%, 7.98-8.80). From the nationwide survey, 405 questionnaires were analysed, there was a female/male ratio of 2.2:1. The mean age of onset of symptoms was 38.7 years (range 1-89). The onset was ocular in 46.4%, oculobulbar in 11.6%, bulbar in 8.9%, limbs in 11.6% and generalized in 21.4%. Of the 13.3% of patients who had had a diagnosis of thymoma, only four of these patients were >60 years old at onset. Thymomas were commoner in patients living in mining counties. Patients ≥60 years old at onset of MG formed 19.5% of the sample, female/male ratio 0.97:1. Associated autoimmune diseases were reported in 14% of patients and in family members of 31.8% of patients. A total of 78 patients had to change work due to MG and 68 needed help in carrying out daily activities.

CONCLUSIONS

This study reduces the gap in information about MG in South America. The prevalence of MG in Chile is within the range described worldwide. We did not see an increase in male frequency in the older age of onset group and thymoma was more frequent in the fifth and sixth decades.

Optimization and Control of Agent-Based Models in Biology: A Perspective

Agent-based models (ABMs) have become an increasingly important mode of inquiry for the life sciences. They are particularly valuable for systems that are not understood well enough to build an equation-based model. These advantages, however, are counterbalanced by the difficulty of analyzing and using ABMs, due to the lack of the type of mathematical tools available for more traditional models, which leaves simulation as the primary approach. As models become large, simulation becomes challenging. This paper proposes a novel approach to two mathematical aspects of ABMs, optimization and control, and it presents a few first steps outlining how one might carry out this approach. Rather than viewing the ABM as a model, it is to be viewed as a surrogate for the actual system. For a given optimization or control problem (which may change over time), the surrogate system is modeled instead, using data from the ABM and a modeling framework for which ready-made mathematical tools exist, such as differential equations, or for which control strategies can explored more easily. Once the optimization problem is solved for the model of the surrogate, it is then lifted to the surrogate and tested. The final step is to lift the optimization solution from the surrogate system to the actual system. This program is illustrated with published work, using two relatively simple ABMs as a demonstration, Sugarscape and a consumer-resource ABM. Specific techniques discussed include dimension reduction and approximation of an ABM by difference equations as well systems of PDEs, related to certain specific control objectives. This demonstration illustrates the very challenging mathematical problems that need to be solved before this approach can be realistically applied to complex and large ABMs, current and future. The paper outlines a research program to address them.

Vascular endothelial growth factor serum concentrations in hypercholesterolemic patients

OBJECTIVE

Vascular endothelial growth factor (VEGF) promotes normal and pathological angiogenesis. VEGF is a chemotactic factor for macrophages and vascular smooth muscle cells, and induces synthesis of metalloproteinases and adhesion molecules. VEGF expression is regulated by hypoxia, cytokines, oncogenes, and oxidized low-density lipoprotein (LDL). The purpose of this study was to determine the relationship between levels of lipid parameters and VEGF, to investigate whether pravastatin treatment influences VEGF serum concentrations, and to examine the relationship between VEGF and the variations in post-treatment lipid and inflammatory parameters.

MATERIAL AND METHODS

Eighteen patients aged 48+/-6.8 years with total cholesterol (TC) >6.1 mmol/L comprised the hypercholesterolemic group. The controls included 12 individuals aged 50+/-7.4 years with TC <5.1 mmol/L. TC, high-density lipoprotein cholesterol (HDLC), triglycerides, LDLC, C-reactive protein (CRP), and VEGF were determined in both groups at baseline, and in the hypercholesterolemic group after 4 months of treatment with 20 mg/day pravastatin.

RESULTS

A significant correlation was observed between concentrations of VEGF and TC, LDLC and TG, and a significant difference in VEGF concentration was observed between the control group (mean 142 ng/L) and the hypercholesterolemic group (mean 272.9 ng/L). A significant decrease was observed in TC (14.7 %), LDLC (21.5 %), CRP (22.7 %), and VEGF (14.8 %) after 4 months of treatment with pravastatin.

CONCLUSIONS

A relationship was found between serum levels of VEGF and most atherogenic lipoproteins. In patients with hypercholesterolemia treated with pravastatin, a reduction in VEGF and CRP was seen in addition to lipid decreases.

[Retinopathy of prematurity in the Murcia region of Spain. Incidence and severity]

OBJECTIVE

To determine the incidence and severity of Retinopathy of Prematurity (ROP) in the Murcia region of Spain.

METHODS

This was a retrospective study of all infants born preterm in the Murcia region during 2004, who were screened for ROP. Our screening criteria were: Infants with a gestational age <or= 32 weeks (GA) or with a birth weight <or= 1500 g (BW). We evaluated sex, GA, BW, parity and ophthalmologic evaluation. We then performed a descriptive study and a statistical analysis.

RESULTS

The study sample involved 115 infants with an average GA of 29.67 weeks and BW of 1325 g. The incidence of ROP and severe ROP was 32.1% and 15.6% respectively. The likelihood of the premature infant developing severe ROP was found to be 88.8% if it was born before 29 weeks GA or weighed less than 1000 g BW. Significant differences (p < 0.001), in terms of GA and BW between infants with and without ROP, were found.

CONCLUSIONS

A third of the preterm infants screened for ROP in the Murcia region developed the disease, and the 50% of these required treatment. The current screening criteria used in our region are appropriate. If more restrictive criteria were used, some severe ROP cases would not be detected. In order to be able to modify the current guidelines for screening for ROP, further studies are required.

Critical assessment of the current guidelines for the management and treatment of morbidly obese patients

An interdisciplinary panel of specialists met in Mallorca in the first European Symposium on Morbid Obesity entitled; "Morbid Obesity, an Interdisciplinary Approach". During the two and half days of the meeting, the participants discussed several aspects related to pathogenesis, evaluation, and treatment of morbid obesity. The expert panel included basic research scientists, dietitians and nutritionists, exercise physiologists, endocrinologists, psychiatrists, cardiologists, pneumonologists, anesthesiologists, and bariatric surgeons with expertise in the different weight loss surgeries. The symposium was sponsored by the Balearic Islands Health Department; however, this statement is an independent report of the panel and is not a policy statement of any of the sponsors or endorsers of the Symposium. The prevalence of morbid obesity, the most severe state of the disease, has become epidemic. The current recommendations for the therapy of the morbidly obese comes as a result of a National Institutes of Health (NIH) Consensus Conference held in 1991 and subsequently reviewed in 2004 by the American Society for Bariatric Surgery. This document reviews the work-up evaluation of the morbidly obese patient, the current status of the indications for bariatric surgery and which type of procedure should be recommended; it also brings up for discussion some important real-life clinical practice issues, which should be taken into consideration when evaluating and treating morbidly obese patients. Finally, it also goes through current scientific evidence supporting the potential effectiveness of medical therapy as treatment of patients with morbid obesity.

WITHDRAWN: Drugs for treating neurocysticercosis (tapeworm infection of the brain)

BACKGROUND

Anthelminthic drugs may shrink brain cysts in neurocysticercosis, but can also cause severe adverse effects.

OBJECTIVES

The objective of this review was to assess the effects of drug treatment in human neurocysticercosis in relation to survival, cyst persistence, subsequent seizures and hydrocephalus.

SEARCH STRATEGY

We searched the Cochrane Infectious Diseases Group specialized trials register (September 2002), The Cochrane Central Register of Controlled Trials (The Cochrane Library Issue 3, 2002), MEDLINE (1966 to September 2002), EMBASE (1980 to August 2002), LILACS (September 2002). We contacted researchers and experts in the field, and pharmaceutical companies.

SELECTION CRITERIA

Randomised or quasi-randomised trials comparing a cysticidal drug with a placebo or a control group receiving symptomatic therapy, in patients with neurocystercosis.

DATA COLLECTION AND ANALYSIS

Assessment of trial quality and data extraction was done independently by two reviewers.

MAIN RESULTS

Four studies involving 305 people met the inclusion criteria. None reported on withdrawal of anticonvulsant therapy, headache relief, disability or death as outcomes. A difference just approaching significance was detected between cysticidal therapy and placebo in relation to cyst persistence up to six months (relative risk 0.83, 95% confidence interval 0.70 to 0.99). Two trials reported on seizures after one to two years follow-up and found no difference (relative risk 0.95, 95% 0.59 to 1.51). There was no difference detected for hydrocephalus (relative risk 2.19, 95% confidence interval 0.29 to 16.55).

AUTHORS' CONCLUSIONS

There is insufficient evidence to assess whether cysticidal therapy in neurocysticerosis is associated with beneficial effects.

Parathyroid hormone and bone marker levels in patients with morbid obesity before and after biliopancreatic diversion

BACKGROUND

Scopinaro biliopancreatic diversion (BPD) is associated with malabsorption of calcium and vitamin D, which manifests as a secondary hyperparathyroidism (SHP) and may lead to osteopenia.

METHODS

96 morbidly obese patients were studied (age 19-60 years, 23 men and 73 women, with mean initial BMI 53) following intervention by Scopinaro BPD. The change in iPTH levels, urine DPD, Pyrilinks-D of DPC and serum CTx were studied at 0, 3, 6, 12, 18 and 24 months after surgery. Postoperatively, they were given supplements of calcium and vitamin D3. The control group consisted of 67 non-obese women and 10 men.

RESULTS

The iPTH levels gradually increased after BPD, with a substantial difference compared to presurgery levels at month 6. In spite of the calcium and vitamin D supplements, 77% of the patients with presurgery SHP did maintain high levels of iPTH after 2 years. The percentage of SHP among the patients with normal pre-surgery iPTH was 58%. The basal figures of DPD/cre were significantly higher than in the control group, 9.06 (4.6-13.5) nM/mMcre vs 3.9 (2.8-5.6) in men and 6.75 (5.4-7.9) vs 7.67 (3.3-11.6) in women, but not CTx, 0.24 (0.02-0.89) vs 0.22 (0.07-0.55). After the operation, there was a noticeable increase which persisted at 2 years. There was a lack of correlation between the levels of iPTH and the bone resorption markers, i.e. the first ones decreased from month 6 in men and from month 12 in women, while the levels of iPTH continued to increase.

CONCLUSION

In obese patients, we found no correlation between iPTH levels and BMI. Supplements of calcium and vitamin D did not prevent the appearance of SHP following BPD. The patients with high pre-surgery iPTH levels have a higher risk of malabsorption of calcium and vitamin D. Following malabsorptive bariatric surgery, there is an increase in bone resorption, which results in DPD and CTx increase. Those markers do not correlate with iPTH, and this may suggest that there is a phenomenon of bone reshaping parallel to the loss of weight.

Routine or selective carotid artery shunting for carotid endarterectomy (and different methods of monitoring in selective shunting)

BACKGROUND

Temporary interruption of cerebral blood flow during carotid endarterectomy can be avoided by using a shunt across the clamped section of the carotid artery. This may improve outcome.

OBJECTIVES

The objective of this review was to assess the effect of routine versus selective, or never, shunting during carotid endarterectomy, and to assess the best method for selecting patients for shunting.

SEARCH STRATEGY

For the original review the authors searched the Cochrane Stroke Group trials register, Medline (1966 to 1994), Embase (1980 to 1995) and Index to Scientific and Technical Proceedings (1980 to 1994). They also hand searched Annals of Surgery (1981 to 1995), British Journal of Surgery (1985 to 1995), European Journal of Vascular Surgery (1988 to 1995) and World Journal of Surgery (1978 to 1995). For the updated review, for the dates January 1994 - December 2000 we: 1. Repeated all these searches performed for the original review and developed more comprehensive search strategies for Medline and Embase. The Cochrane Stroke Group Trials Register was last searched in May 2001. 2. Hand searched the Journal of Vascular Surgery, Stroke, Annals of Vascular Surgery, American Journal of Surgery and Cardiovascular Surgery. 3. Hand searched the abstracts from the International Stroke Conference, AGM of the Vascular Surgical Society (UK), AGM of the Association of Surgeons of Great Britain and Ireland and the Annual Meeting of the Society for Vascular Surgery (USA). 4. Searched reference lists from all relevant trials All the authors of studies included in the initial review, and other authors known to have published relevant work, were contacted requesting information about further published or unpublished data.

SELECTION CRITERIA

Randomised and quasi-randomised trials of routine shunting compared with no shunting or selective shunting, and trials that compared different shunting policies in patients undergoing carotid endarterectomy.

DATA COLLECTION AND ANALYSIS

For the original review two reviewers independently performed the searches and applied the inclusion criteria. The data were extracted by one reviewer and double-checked. Trial quality was assessed. During the update, two reviewers independently performed the searches and applied the inclusion criteria. No new relevant randomised controlled trials were found.

MAIN RESULTS

Despite recommendation from the original review that further studies were required, no new trials of adequate quality and fitting the inclusion criteria were found. The initial review included three trials. Two trials involving 590 patients compared routine shunting with no shunting. The other trial involving 131 patients compared shunting with a combination of electroencephalographic and carotid pressure measurement, with shunting by carotid pressure measurement alone. Allocation was adequately concealed in one trial, and one trial was quasi-randomised. Analysis was by intention-to-treat where possible. For routine versus no shunting, there was no significant difference in the rate of all stroke, ipsilateral stroke or death up to 30 days after surgery, although data were limited. There was no significant difference between the risk of ipsilateral stroke in patients selected for shunting with the combination of electroencephalographic and carotid pressure assessment compared to pressure assessment alone, although again the data were limited.

REVIEWER'S CONCLUSIONS

When first published in 1995, this review concluded that the data available were too limited to either support or refute the use of routine or selective shunting in carotid endarterectomy. It was suggested that large scale randomised trials using no shunting as the control group were required. No one method of monitoring in selective shunting has been shown to produce better outcomes. No further prospective randomised or quasi-randomised trials have been performed since then and the conclusions therefore remain unchanged.

[Heart rate and physical activity to assess energy expenditure in children]

The aim of the present study was to validate assessment of oxygen consumption (VO2) from heart rate (HR) and physical activity (PA) electronically recorded. Every minute, mean VO2 were validated with indirect calorimetry. We studied 25 children (12 girls, 13 boys), 12.1 +/- 0.7 years old. Measurements were made during about 60 minutes while kids were supine, sitting, standing and walking at four intensities. Minute by minute heart rate was converted to VO2 and energy expenditure using 2 different functions for active and inactive situations. A linear function (VO2 = a + beta HR) was used when counts were 7 or higher and HR higher than a prefixed point (intersection between the 2 line functions). A nonlinear equation (VO2 = a + beta HR3) was used in the remaining minutes. Mean predicted VO2 for every minute were similar to measured VO2 (2 ways interaction ANOVA, p = 0.99). Mean VO2 correlated significantly with VO2 predicted by equation (r = 0.99, p < 0.01). High degree of agreement was found (Bland-Altman comparisons). Combined heart rate and physical activity predicted oxygen consumption with a precision similar to the indirect calorimetric method.

[Effect of budesonide on bone density and metabolism in asthmatic children]

OBJECTIVE

To assess the effect of inhaled budesonide on the mineral density, content and bone metabolism in children with asthma.

MATERIAL AND METHODS

From September 1996 to July 1997, a cross-sectional study was conducted in 38 prepubertal children aged 6 to 11 years, selected from the pediatric chest outpatient clinic of the Instituto Autónomo Hospital Universitario de Los Andes, Mérida, Venezuela. Three study groups were assembled: 9 asthmatic children treated with inhaled budesonide (300 micrograms/day) for over 6 months (Group A); 14 asthmatic children not treated with inhaled corticosteroids (Group B); and 15 non-asthmatic children (Group C). All of them underwent testing of bone formation and resorption markers, and measurement of bone mineral density (DMO) and content (CMO). Statistical analysis consisted of central tendency and dispersion measures, analysis of variance, and Fisher and Scheffe tests for comparison of means.

RESULTS

In the groups studied (A, B, and C) calcium serum levels were 9.1 +/- 0.3; 9.6 +/- 0.4; 9.3 +/- 0.6 mg/ml, respectively; osteocalcin levels were 14.8 +/- 4.6; 13.0 +/- 2.5; 11.9 +/- 3.4 ng/dl; the type I collagen carboxyterminal telopeptide (ICTP) levels were 19.6 +/- 16.5; 14.2 +/- 15.4; 13.0 +/- 18.3 micrograms/l; the DMO levels were 0.67 +/- 0.06; 0.68 +/- 0.06; 0.69 +/- 0.06 g/cm2; and the CMO levels were 1,158.8 +/- 217.4; 1,106.4 +/- 256.1; 1,176.5 +/- 240.5 g, respectively. No statistically significant differences were observed between the groups.

CONCLUSIONS

The administration of 100-400 micrograms/day of inhaled budesonide for a period of six months, did not change the bone mineral density and metabolism of asthmatic children.

Drugs for treating neurocysticercosis (tapeworm infection of the brain)

BACKGROUND

Anthelminthic drugs may shrink brain cysts in neurocysticercosis, but can also cause severe adverse effects.

OBJECTIVES

The objective of this review was to assess the effects of drug treatment in human neurocysticercosis in relation to survival, cyst persistence, subsequent seizures and hydrocephalus.

SEARCH STRATEGY

We searched the Cochrane Infectious Diseases Group trials register and Medline. We contacted researchers and experts in the field and drug manufacturers.

SELECTION CRITERIA

Randomised or quasi-randomised trials comparing a cysticidal drug with a placebo or a control group receiving symptomatic therapy, in patients with neurocystercosis.

DATA COLLECTION AND ANALYSIS

Assessment of trial quality and data extraction was done independently by two reviewers.

MAIN RESULTS

Four studies involving 305 people met the inclusion criteria. None reported on withdrawal of anticonvulsant therapy, headache relief, disability or death as outcomes. A difference just approaching significance was detected between cysticidal therapy and placebo in relation to cyst persistence up to six months (relative risk 0.83, 95% confidence interval 0.70 to 0.99). Two trials reported on seizures after one to two years follow-up and found no difference (relative risk 0.95, 95% 0.59 to 1.51). There was no difference detected for hydrocephalus (relative risk 2.19, 95% confidence interval 0.29 to 16.55).

REVIEWER'S CONCLUSIONS

There is insufficient evidence to assess whether cysticidal therapy in neurocysticerosis is associated with beneficial effects.

Patch angioplasty versus primary closure for carotid endarterectomy

BACKGROUND

Carotid patch angioplasty (with either a venous or a synthetic patch) may reduce the risk of carotid artery restenosis and subsequent ischaemic stroke.

OBJECTIVES

The objective of this review was to assess the effect of routine or selective carotid patch angioplasty compared to carotid endarterectomy with primary closure.

SEARCH STRATEGY

We searched the Cochrane Stroke Group trials register, Medline (1966 to 1995), Embase (1980 to 1995) and Index to Scientific and Technical Proceedings (1980 to 1994). We handsearched Annals of Surgery (1981 to 1995), British Journal of Surgery (1985 to 1995), European Journal of Vascular and Endovascular Surgery (1987 to 1995) and World Journal of Surgery (1978 to 1995).

SELECTION CRITERIA

Randomised trials comparing carotid patch angioplasty with primary closure in any patients undergoing carotid endarterectomy.

DATA COLLECTION AND ANALYSIS

Two reviewers independently assessed eligibility, trial quality and extracted the data.

MAIN RESULTS

Six trials involving 794 patients and 882 operations were included. The quality of trials was generally poor. Follow-up varied from hospital discharge to five years. Carotid patch angioplasty showed a reduction in the risk of stroke of any type, ipsilateral stroke, and stroke or death, during the perioperative period and longterm follow-up. However, data were not available from all trials, the number of events was small and there was significant loss to follow-up. Patching appeared to reduce the risk of perioperative arterial occlusion (six trials, odds ratio 0.17, 95% confidence interval 0.06 to 0.46). Patching was also associated with decreased restenosis during longterm follow-up in five trials, (odds ratio 0.32, 95% confidence interval 0.19 to 0.53). However, these results are uncertain because of loss to follow-up and the small number of events. Very few arterial complications, including haemorrhage, infection, cranial nerve palsies and pseudo-aneurysm formation were recorded with either patch or primary closure.

REVIEWER'S CONCLUSIONS

Limited evidence suggests that carotid patch angioplasty may lower the risk of perioperative arterial occlusion and restenosis. It is unclear whether this reduces the risk of death or stroke.

Treating neurocysticercosis medically: a systematic review of randomized, controlled trials

OBJECTIVE

To summarize the evidence from randomized controlled trials on the effects of cysticidal therapy used for treating human cysticercosis.

METHODS

Published and unpublished studies in any language identified through MEDLINE (1966 - June 1999) specialized databases, abstracts, proceedings and contact with experts were analysed. Those which compared, using randomized or quasi-randomized methods, any cysticidal drug with placebo or symptomatic therapy were entered in the study. Data were extracted independently by two reviewers and trial quality assessed. Meta-analysis using fixed effects models calculated provided there was no significant heterogeneity, expressed as relative risk.

RESULTS

Four trials met the inclusion criteria, treating intraparenchymatous neurocysticercosis with either albendazole or praziquantel compared to placebo or no treatment. In the two trials reporting clinical outcomes, treatment was not associated with a reduction in the risk of seizures, although numbers were small (RR 0.95, 95% CI 0.59-1.51). Four trials reported radiological outcomes, and cysticidal treatment was associated with a lower risk of cyst persistence of scans taken within six months of start of treatment (RR 0.83, 95% CI 0.70-0.99). Subsidiary analysis assuming different outcomes in patients lost to follow-up did not alter the findings of the main analysis.

CONCLUSIONS

There is insufficient evidence to determine whether cysticidal therapy is of any clinical benefit to patients with neurocysticercosis. The review does not exclude the possibility that more patients remain seizure-free when treated with cysticidal drugs. Further testing through placebo-controlled trials is required.

Oral transmucosal fentanyl citrate as an additional premedicant for adult cardiac surgery patients

OBJECTIVE

To investigate the efficacy of a combination of midazolam and oral transmucosal fentanyl citrate (OTFC) as a preoperative medication for adult cardiac surgery patients compared with the use of midazolam alone.

DESIGN

A randomized, prospective study.

SETTING

University teaching hospital.

PARTICIPANTS

Patients scheduled for elective coronary artery bypass surgery.

INTERVENTIONS

All patients were given 50 micrograms/kg of midazolam intramuscularly in their rooms. Group I received 300 micrograms of OTFC Oralet (Anesta Corp, Salt Lake City, UT) if they weighed less than 70 kg and 400 micrograms of OTFC Oralet if they weighed more than 70 kg. Group II received a placebo Oralet. A radial artery catheter, two internal jugular venous catheters, and a pulmonary artery catheter inserted through one of the internal jugular catheters were placed in each study patient. Fentanyl was administered intravenously as a rescue drug.

MEASUREMENTS AND MAIN RESULTS

Ninety percent of midazolam/OTFC patients reported feeling no pain during catheter placement, compared with 50% of midazolam/placebo patients. Fifty percent of the placebo group required fentanyl supplement of 50 micrograms intravenously because of complaints of pain, compared with 10% of the OTFC group. The midazolam/OTFC group scored approximately 20% better than the placebo group in the independent observer score of patient analgesia and the anesthesiologist rating for ease of invasive catheter placement. No myocardial ischemic events were noted in either group as determined by electrocardiogram. All patients found the Oralet mode of delivery very acceptable.

CONCLUSIONS

The OTFC Oralet provides effective analgesia and sedation when combined with midazolam for invasive catheter placement in adult cardiac surgery patients. The OTFC Oralet with its gradual onset lessens the possibility of overmedicating with fentanyl, and it offers a very acceptable mode of delivery for a preemptive analgesic.

A systematic review of the randomised trials of carotid patch angioplasty in carotid endarterectomy

OBJECTIVES

To determine whether patch angioplasty is more effective than primary closure in carotid endarterectomy, and whether one type of patch is better than another.

DESIGN

Systematic review of the randomised trials.

MATERIALS

Trials were identified from the Cochrane Stroke Review Group database plus additional handsearching, electronic searching, and personal contact.

METHODS

Two authors independently selected studies for inclusion and extracted details of trial quality and data on the following outcomes: any stroke; stroke ipsilateral to the operated artery; death; occlusion or restenosis, and other significant arterial complications. Meta-analysis of odds ratios (OR) was performed using the Peto method.

RESULTS

Six trials (882 operations) compared routine patching with primary closure. Routine patching was associated with significant reductions in the risks of ipsilateral stroke during the perioperative period (OR 0.34, 95% CI 0.15-0.76) and during long-term follow-up (OR 0.38, 95% CI 0.16-0.88). Significant reductions in the odds of any stroke, stroke or death, acute arterial occlusion and long-term restenosis were also found. However, these results were based on very small numbers of outcome events and may be biased by losses to follow-up and publication bias. Three trials (326 operations) compared the use of polytetrafluoroethylene patches with venous patches. There were too few events (strokes, deaths, arterial complications) to determine whether there were significant differences between the patch materials. Fewer pseudoaneurysms occurred in those who received synthetic patches but the clinical consequence of this was unclear.

CONCLUSIONS

Routine carotid patch angioplasty was associated with promising reductions in the risks of ipsilateral stroke and death, but the results should be interpreted cautiously because of the small number of outcome events, significant losses to follow-up, and poor trial methodology. Ideally, a large definitive trial should be performed. There is insufficient evidence to support the preferential use of one particular type of patch versus another.

[Organizational models for the hematology areas of the district hospitals of Catalonia]

PURPOSE

The haematological assistance in Catalonia is based upon the district hospitals, in the first step, and the stage III hospitals located usually in higher population nuclei, in the second step. The purpose of this work was to analyse the resources of the "primary haematological assistance" network provided by the district hospitals, to evaluate them and to propose a model for their organisation.

MATERIAL AND METHODS

An enquiry was carried out to all members of the Grup de Treball d'Hospitals Comarcals de Catalunya (Catalonia's District Hospitals Task Force). The evaluable data included demographic figures of the population assisted, personnel of each haematological area, organising structure, clinical activity, cytomorphology, blood banks, laboratories and continuous formation activities.

RESULTS

The enquiry was answered by 15 of the 21 district hospitals (71.4%) with haematologists in Catalonia. The population assisted in those hospitals is 2,100,000 (ranging between 55,000 an 450,000). All centres are integrated in the National Health network. Eleven of the hospitals analysed have only one haematologist (73.3%). If his dedication is 100% of the time, this would represent a doctor for 105,000 people. The time devoted to work is 690 hours a week for all the population, with a mean of 3,043. Four patients assisted per hour. The total number of hospital beds is 3,353 (50-450), with a mean number of 1 haematologist for every 167.6 beds. The number of patients hospitalized due to blood diseases ranges between 3 and 13 per month. Six of the 15 centres are adjunct to the outpatient clinic. Two centres have a blood bank and 7 have developed an autotransfusion programme. All the centres but one perform oral anticoagulant treatment follow-up, the number of patients assisted ranging from 20 to 210 per week. None of the hospitals has a separate Haematology Service; in most of them haematology is structurally and functionally dependent from Laboratories and in some there is a mixed Laboratory/Internal Medicine functional organisation, depending of the Medical Direction. No haematologist is ever on call specifically for his specialty. Continuous formation activities are carried out in 9 of the 15 centres (60%).

COMMENT

Several measures are proposed to improve the haematological assistance, acting on different levels: continuous formation, patient flows and circuits, resident doctors training, anticoagulant treatment network, organisation models, credit cards from the Spanish Association of Haematology.

[Macrosomia and death. Relationship with maternal diabetes]

The incidence of macrosomic newborns and fetal death and its possible relation to maternal diabetes mellitus (DM) was registered during six months at the Hospital de Ginecoobstetricia "Dr. I. Morones", IMSS. Both criteria for macrosomia 4,000 g and 4,500 g, were taken for data collection. We had a total of 15,217 newborns, of these, 872 (5.73%), weighed > 4,000 g, and there were 42 mothers with DM, 4.2% of the group. Taking 4,500 g as criteria for macrosomia, there were 105 newborns (0.69%) of the total and there were 8 mothers with DM, 7.6%. 501 of the pregnancies finished by cesarean section and 337 by delivery. There were 151 fetal deaths, 9.9 for 1,000 newborns, eight fetuses had a weight over 4,000 g, and two mothers had DM. It is concluded that maternal diabetes mellitus occurred in less than 5% of the mothers with macrosomic newborns (> 4,000 g). The incidence of macrosomia is lower than in European populations. Fetal deaths were higher than expected because this hospital concentrates patients with obstetrical complications.

Does the angiographic appearance of a carotid stenosis predict the risk of stroke independently of the degree of stenosis?

We aimed to determine whether the angiographic characteristics of recently symptomatic carotid stenosis predict risk of subsequent ischaemic stroke independently of the degree of stenosis. First, two observers compared the angiographic characteristics of patients who subsequently suffered a carotid distribution ischaemic stroke ipsilateral to the stenosis (n = 50) with those of stroke-free controls (n = 100) matched for the degree of stenosis of the symptomatic internal carotid artery. No significant differences were found. Secondly, seven independent observers attempted to identify the angiograms of 50 patients who subsequently suffered a stroke from those of 50 stroke-free controls matched for degree of stenosis, age and sex. None of the observers identified the stroke case more often than was expected by chance alone. We conclude that clinicians cannot differentiate between 'high risk' and 'low risk' carotid stenoses on the basis of angiographic characteristics other than the degree of stenosis.

A new formula for prenatal ultrasonographic weight estimation in extremely preterm fetuses

A new formula for the prenatal estimation of the weight of extremely preterm fetuses was derived using ultrasound measurements and birth weights of 73 premature infants delivered before 30 completed weeks of pregnancy and weighing between 400 and 1,680 g at birth. The actual birth weight lay within +/- 15% of the estimated weight calculated with this formula in 92% of the cases. Preliminary testing of the reliability of the formula was performed on a further test group of 19 nonselected cases. The formula developed in this study offers a reliable and simple method of prenatal estimation of fetal weight between 23 and 30 weeks of gestation.

Trends and survival in AIDS-associated malignancies

Data from 1569 AIDS cases reported to the population-based AIDS Registry of Catalonia have been analysed to describe the epidemiology and temporal evolution of both Kaposi's sarcoma (KS) and non-Hodgkin lymphoma (NHL). Of the 1569 cases reported, 53 (3.4%) presented with NHL and 135 (8.6%) with KS. KS cases were more frequent among homosexual/bisexual men and the age of KS cases was significantly higher than all others presenting diseases (38.22 years). NHL cases were more frequently among men but no significant age difference was found. The percentage of KS over time decreased significantly only among intravenous drug users. Cases presenting with a NHL had by far the worst prognosis (median survival time = 169 days). Biases affecting the measurement of AIDS associated malignancies (AAM) using surveillance data are analysed. The prevalence of AAM will increase during the next few years, and NHL may be one of the leading causes of death among AIDS patients in the near future.

Impaired response to recombinant hepatitis B vaccine in HIV-infected persons

We studied the immunogenicity of the standard schedule of recombinant hepatitis B vaccine (20 micrograms per dose at months 0, 1, and 6) in 21 anti-human immunodeficiency virus (HIV)-positive persons. Relatively low titers of anti-HBs developed in only five subjects (23.8%) 1 month after the third dose; all five had T4 cell counts greater than 700 cells/mm and none of the 11 subjects with a T4 cell count below this value responded. Five of the 16 nonresponders to the vaccine later had acquired immunodeficiency syndrome (AIDS)-related complex (two) and AIDS (three), while none of the responders did. Our results show that anti-HIV-positive persons are poor responders to the recombinant hepatitis B vaccine, and that the absence of a response is an indicator of a more severe immune deficiency and of a poor prognosis. An optimal regimen of hepatitis B vaccination in HIV-infected persons is still to be established.