A repeating fast radio burst source in a globular cluster

Fast radio bursts (FRBs) are flashes of unknown physical origin¹. The majority of FRBs have been seen only once, although some are known to generate multiple flashes^2,3. Many models invoke magnetically powered neutron stars (magnetars) as the source of the emission^4,5. Recently, the discovery⁶ of another repeater (FRB 20200120E) was announced, in the direction of the nearby galaxy M81, with four potential counterparts at other wavelengths⁶. Here we report observations that localized the FRB to a globular cluster associated with M81, where it is 2 parsecs away from the optical centre of the cluster. Globular clusters host old stellar populations, challenging FRB models that invoke young magnetars formed in a core-collapse supernova. We propose instead that FRB 20200120E originates from a highly magnetized neutron star formed either through the accretion-induced collapse of a white dwarf, or the merger of compact stars in a binary system⁷. Compact binaries are efficiently formed inside globular clusters, so a model invoking them could also be responsible for the observed bursts.

Chronic pain after open inguinal hernia repair: expertise-based randomized clinical trial of heavyweight or lightweight mesh

BACKGROUND

There is a shortage of high-quality studies regarding choice of mesh in open anterior inguinal hernia repair in relation to long-term chronic pain. The authors hypothesized that heavyweight compared with lightweight mesh causes increased postoperative pain.

METHODS

An RCT was undertaken between 2007 and 2009 at two sites in Sweden. Men aged 25 years or older with an inguinal hernia evaluated in the outpatient clinic were randomized in an unblinded fashion to heavyweight or lightweight mesh for open anterior inguinal hernia repair. Data on pain affecting daily activities, as measured by the Short-Form Inguinal Pain Questionnaire 9-12 years after surgery, were collected as the primary outcome. Differences between groups were evaluated by generalized odds and numbers needed to treat.

RESULTS

A total of 412 patients were randomized; 363 were analysed with 320 questionnaires sent out. A total of 271 questionnaires (84.7 per cent) were returned; of these, 121 and 150 patients were in the heavyweight and lightweight mesh groups respectively. Pain affecting daily activities was more pronounced in patients randomized to heavyweight versus lightweight mesh (generalized odds 1.33, 95 per cent c.i. 1.10 to 1.61). This translated into a number needed to treat of 7.06 (95 per cent c.i. 4.28 to 21.44). Two reoperations for recurrence were noted in the heavyweight mesh group, and one in the lightweight mesh group.

CONCLUSION

A large-pore lightweight mesh causes significantly less pain affecting daily activities a decade after open anterior inguinal hernia repair. Registration number: NCT00451893 (http://www.clinicaltrials.gov).

The circumstellar envelope around the S-type AGB star W Aql. Effects of an eccentric binary orbit

CONTEXT

Recent observations at subarcsecond resolution, now possible also at submillimeter wavelengths, have shown intricate circumstellar structures around asymptotic giant branch (AGB) stars, mostly attributed to binary interaction. The results presented here are part of a larger project aimed at investigating the effects of a binary companion on the morphology of circumstellar envelopes (CSEs) of AGB stars.

AIMS

AGB stars are characterized by intense stellar winds that build CSEs around the stars. Here, the CO(J = 3→2) emission from the CSE of the binary S-type AGB star W Aql has been observed at subarcsecond resolution using ALMA. The aim of this paper is to investigate the wind properties of the AGB star and to analyse how the known companion has shaped the CSE.

METHODS

The average mass-loss rate during the creation of the detected CSE is estimated through modelling, using the ALMA brightness distribution and previously published single-dish measurements as observational constraints. The ALMA observations are presented and compared to the results from a 3D smoothed particle hydrodynamics (SPH) binary interaction model with the same properties as the W Aql system and with two different orbital eccentricities. Three-dimensional radiative transfer modelling is performed and the response of the interferometer is modelled and discussed.

RESULTS

The estimated average mass-loss rate of W Aql is Ṁ = 3.0×10-6 M⊙ yr-1 and agrees with previous results based on single-dish CO line emission observations. The size of the emitting region is consistent with photodissociation models. The inner 10″ of the CSE is asymmetric with arc-like structures at separations of 2-3″ scattered across the denser sections. Further out, weaker spiral structures at greater separations are found, but this is at the limit of the sensitivity and field of view of the ALMA observations.

CONCLUSIONS

The CO(J = 3→2) emission is dominated by a smooth component overlayed with two weak arc patterns with different separations. The larger pattern is predicted by the binary interaction model with separations of ~10″ and therefore likely due to the known companion. It is consistent with a binary orbit with low eccentricity. The smaller separation pattern is asymmetric and coincides with the dust distribution, but the separation timescale (200 yrs) is not consistent with any known process of the system. The separation of the known companions of the system is large enough to not have a very strong effect on the circumstellar morphology. The density contrast across the envelope of a binary with an even larger separation will not be easily detectable, even with ALMA, unless the orbit is strongly asymmetric or the AGB star has a much larger mass-loss rate.

From population genomics to conservation and management: a workflow for targeted analysis of markers identified using genome-wide approaches in Atlantic salmon Salmo salar

A genotyping assay for the Ion Torrent Ion PGM platform was developed for fast and cost-effective targeted genotyping of key single nucleotide polymorphisms (SNPs) earlier identified using a genome-wide SNP array in Atlantic salmon Salmo salar. The method comprised a simple primer design step for multiplex-polymerase chain reaction (PCR), followed by two rounds of Ion Torrent Ion PGM sequencing to empirically evaluate marker efficiency in large multiplexes and to optimise or exclude them when necessary. Of 282 primer pairs initially tested, 217 were successfully amplified, indicating good amplification success (>75%). These markers included the sdy partial gene product to determine genetic sex, as well as three additional modules comprising SNPs for assessing neutral genetic variation (N_SNP = 150), examining functional genetic variation associated with sea age at maturity (N_SNP = 5), and for performing genetic subpopulation assignment (N_SNP = 61). The assay was primarily developed to monitor long-term genetic changes in S. salar from the Teno River, but modules are likely suitable for application in a wide range of S. salar populations. Furthermore, the fast and versatile assay development pipeline offers a strategy for developing targeted sequencing assays in any species.

Target Delineation in Radiosurgery for Cerebral Arteriovenous Malformations

A study of 6 selected arteriovenous malformation (AVM) patients was performed to investigate the feasibility of delineating an AVM on MR images and to compare the AVM volume outlined on different images. Conventional stereotaxic angiograms, stereotaxic MR images and MR angiograms using several different pulse sequences were obtained prior to radiosurgery. Treatment plans were made from the conventional stereotaxic angiograms. These plans were then transferred to a separate dose planning computer which displayed the MR images with the superimposed isodose lines. The radiated volumes of AVM and brain tissue were measured from these MR images. Last, an assessment was made of the radiation volume needed for an appropriate treatment of the AVM if the treatment plan was made from the MR images rather than from the conventional stereotaxic angiogram. It was possible to delineate medium and large size AVM nidi on stereotaxic MR images based on an integration of information obtained from various pulse sequences. The estimated volumes of the AVM nidi were found to be larger on the conventional stereotaxic angiograms than on the stereotaxic MR images. Consequently, a dose plan based on a conventional stereotaxic angiogram would result in a higher integral dose to the brain with the same target dose. By using reliable MR information it is expected that the volume of brain exposed to radiation could be decreased and the adverse effects of stereotactic radiosurgery for AVM thereby minimized.

Long-term persistence of a multi-resistant methicillin-susceptible Staphylococcus aureus (MR-MSSA) clone at a university hospital in southeast Sweden, without further transmission within the region

The objective of this study was to characterise isolates of methicillin-susceptible Staphylococcus aureus (MSSA) with resistance to clindamycin and/or tobramycin in southeast Sweden, including the previously described ECT-R clone (t002) found in Östergötland County, focusing on clonal relatedness, virulence determinants and existence of staphylococcal cassette chromosome (SCC) mec remnants. MSSA isolates with resistance to clindamycin and/or tobramycin were collected from the three county councils in southeast Sweden and investigated with spa typing, polymerase chain reaction (PCR) targeting the SCCmec right extremity junction (MREJ) and DNA microarray technology. The 98 isolates were divided into 40 spa types, and by microarray clustered in 17 multi-locus sequence typing (MLST) clonal complexes (MLST-CCs). All isolates with combined resistance to clindamycin and tobramycin (n = 12) from Östergötland County and two additional isolates (clindamycin-R) were designated as spa type t002, MREJ type ii and were clustered in CC5, together with a representative isolate of the ECT-R clone, indicating the clone's persistence. These isolates also carried several genes encoding exotoxins, Q9XB68-dcs and qacC. Of the isolates in CC15, 83% (25/30) were tobramycin-resistant and were designated spa type t084. Of these, 68% (17/25) were isolated from new-borns in all three counties. The persistence of the ECT-R clone in Östergötland County, although not found in any other county in the region, carrying certain virulence factors that possibly enhance its survival in the hospital environment, highlights the fact that basic hygiene guidelines must be maintained even when MRSA prevalence is low.

Detection and characterisation of SCCmec remnants in multiresistant methicillin-susceptible Staphylococcus aureus causing a clonal outbreak in a Swedish county

The purpose of this study was to investigate if multiresistant methicillin-susceptible Staphylococcus aureus (MR-MSSA) causing a clonal outbreak in Östergötland County, Sweden, were derived from methicillin-resistant S. aureus (MRSA) by carrying remnants of SCCmec, and, if so, to characterise this element. A total of 54 MSSA isolates with concomitant resistance to erythromycin, clindamycin and tobramycin from 49 patients (91% clonally related, spa type t002) were investigated with the BD GeneOhm MRSA assay and real-time polymerase chain reaction (PCR) targeting the SCCmec integration site/SCCmec right extremity junction. DNA sequencing of one isolate representing the MR-MSSA outbreak clone was performed by massive parallel 454 pyrosequencing. All isolates that were part of the clonal outbreak carried SCCmec remnants. The DNA sequencing revealed the carriage of a pseudo-SCC element 12 kb in size, with a genomic organisation identical to an SCCmec type ΙΙ element, except for a 41-kb gap. This study demonstrates the presence of a pseudo-SCC element resembling SCCmec type II among MR-MSSA, suggesting possible derivation from MRSA. The presence of SCCmec remnants should always be considered when SCCmec typing is used for MRSA detection, and may not be suitable in locations with a high prevalence of MR-MSSA, since this might give a high number of false-positive results.

No induction of thiopurine methyltransferase during thiopurine treatment in inflammatory bowel disease

The aim of this study was to follow, during standardized initiation of thiopurine treatment, thiopurine methyltransferase (TPMT) gene expression and enzyme activity and thiopurine metabolite concentrations, and to study the role of TPMT and ITPA 94C > A polymorphisms for the development of adverse drug reactions. Sixty patients with ulcerative colitis or Crohn's disease were included in this open and prospective multi-center study. Thiopurine naïve patients were prescribed azathioprine (AZA), patients previously intolerant to AZA received 6-mercaptopurine (6-MP). The patients followed a predetermined dose escalation schedule, reaching target dose at Week 3; 2.5 and 1.25 mg/kg body weight for AZA and 6-MP, respectively. The patients were followed every week during Weeks 1-8 from baseline and then every 4 weeks until 20 weeks. TPMT activity and thiopurine metabolites were determined in erythrocytes, TPMT and ITPA genotypes, and TPMT gene expression were determined in whole blood. One homozygous TPMT-deficient patient was excluded. Five non compliant patients were withdrawn during the first weeks. Twenty-seven patients completed the study per protocol; 27 patients were withdrawn because of adverse events. Sixty-seven percent of the withdrawn patients tolerated thiopurines at a lower dose at Week 20. There was no difference in baseline TPMT enzyme activity between individuals completing the study and those withdrawn for adverse events (p = 0.45). A significant decrease in TPMT gene expression (TPMT/huCYC ratio, p = 0.02) was found, however TPMT enzyme activity did not change. TPMT heterozygous individuals had a lower probability of remaining in the study on the predetermined dose (p = 0.039). The ITPA 94C > A polymorphism was not predictive of adverse events (p = 0.35).

Pharmacogenetics during standardised initiation of thiopurine treatment in inflammatory bowel disease

BACKGROUND

Firm recommendations about the way thiopurine drugs are introduced and the use of thiopurine methyltransferase (TPMT) and metabolite measurements during treatment in inflammatory bowel disease (IBD) are lacking.

AIM

To evaluate pharmacokinetics and tolerance after initiation of thiopurine treatment with a fixed dosing schedule in patients with IBD.

PATIENTS

60 consecutive patients with Crohn's disease (n = 33) or ulcerative colitis (n = 27) were included in a 20 week open, prospective study.

METHODS

Thiopurine treatment was introduced using a predefined dose escalation schedule, reaching a daily target dose at week 3 of 2.5 mg azathioprine or 1.25 mg 6-mercaptopurine per kg body weight. TPMT and ITPA genotypes, TPMT activity, TPMT gene expression, and thiopurine metabolites were determined. Clinical outcome and occurrence of adverse events were monitored.

RESULTS

27 patients completed the study per protocol, while 33 were withdrawn (early protocol violation (n = 5), TPMT deficiency (n = 1), thiopurine related adverse events (n = 27)); 67% of patients with adverse events tolerated long term treatment on a lower dose (median 1.32 mg azathioprine/kg body weight). TPMT activity did not change during the 20 week course of the study but a significant decrease in TPMT gene expression was found (TPMT/huCYC ratio; p = 0.02). Patients with meTIMP concentrations >11,450 pmol/8 x 10(8) red blood cells during steady state at week 5 had an increased risk of developing myelotoxicity (odds ratio = 45.0; p = 0.015).

CONCLUSIONS

After initiation of thiopurine treatment using a fixed dosing schedule, no general induction of TPMT enzyme activity occurred, though TPMT gene expression decreased. The development of different types of toxicity was unpredictable, but we found that measurement of meTIMP early in the steady state phase helped to identify patients at risk of developing myelotoxicity.

Adverse events leading to modification of therapy in a large cohort of patients with inflammatory bowel disease

BACKGROUND

Adverse events leading to discontinuation or dose reduction of thiopurine therapy occur in 9-28% of patients with inflammatory bowel disease.

AIMS

To evaluate the influence of thiopurine methyltransferase status and thiopurine metabolites in a large patient population for the risk of developing adverse event.

METHODS

Three hundred and sixty-four patients with inflammatory bowel disease and present or previous thiopurine therapy were identified from a local database.

RESULTS

The adverse event observed in 124 patients (34%) were more common in adults than children (40% vs. 15%; P < 0.001) and in low to intermediate (<or=9.0 U/mL red blood cell) than normal thiopurine methyltransferase activity (P = 0.02). Myelotoxicity developed later than other types of adverse event. An increased frequency of adverse event was observed in patients with tioguanine (thioguanine) nucleotide above 400 or methylated thioinosine monophosphate above 11 450 pmol/8 x 10(8) red blood cell. A shift to mercaptopurine was successful in 48% of azathioprine-intolerant patients and in all cases of azathioprine-induced myalgia or arthralgia.

CONCLUSIONS

A pre-treatment determination of thiopurine methyltransferase status might be appropriate as patients with low to intermediate thiopurine methyltransferase activity are more prone to develop an adverse event; determination of metabolite levels can be useful in the case of an adverse event. Mercaptopurine therapy should be considered in azathioprine-intolerant patients.

Impaired Transport as a Mechanism of Resistance to Thiopurines in Human T-Lymphoblastic Leukemia Cells

In order to better understand the mechanisms of resistance to thiopurines, we studied two sublines of the MOLT4 T-lymphoblastic leukemia cell line, resistant to 6-mercaptopurine (6-MP) and 6-thioguanine (6-TG). We found that the underlying mechanism of resistance in both resistant cell lines was a markedly reduction in initial transport of 6-MP (3- and 5-fold, respectively, in 6-MP- and 6-TG-resistant cells). No significant alteration of activities of hypoxanthine-guanine phosphoribosyl transferase, thiopurine methyltransferase or inosine monophosphate dehydrogenase, the key enzymes involved in the metabolism of thiopurines was detected. We conclude that defected initial transport of thiopurines by cells may very well explain their resistance to these drugs.

Gastric emptying and duodeno-gastro-oesophageal reflux in gastro-oesophageal reflux disease

BACKGROUND

Previous studies present conflicting results regarding relationship between gastric emptying and gastro-oesophageal reflux disease. Reflux of duodenal content to oesophagus is generally considered to be associated with more severe disease.

AIM

To assess presence of a gastric emptying disorder in persons with reflux of duodenal contents to oesophagus and to identify any correlation with gastric emptying and oesophageal motility.

METHODOLOGY

A total of 15 subjects with (B+) and 15 subjects without (B-) bile reflux to oesophagus determined by 24-hour bilirubin monitoring were studied with scintigraphic solid gastric emptying and 24-hour oesophageal manometry.

RESULTS

There was no difference in lag phase [median 23.7 (range 10.8-44.0) vs 24.6 (8.1-40.1) min], half emptying time [74.6 (48.0-93.6) vs 82.8 (54.4-153.9) min] or emptying rate [0.89 (0.59-1.34) vs 0.83 (0.36-1. 15)%/min] for B- and B+ subjects, respectively. In addition, there was no difference in emptying rate of gastric fundus between B- and B+ subjects. Subjects with bile reflux had less effective oesophageal contractions of oesophageal body [9.4(3.3-37)%] compared to subjects without bile reflux [32(19-47)%, p = 0.002]. However, there was no correlation between oesophageal motility and gastric emptying.

CONCLUSION

Results suggest that a gastric emptying disorder is a less likely contributing cause of bile reflux to the oesophagus, but bile reflux is associated with less effective oesophageal motility.

Diagnostic performance of duplex ultrasonography in the detection of high grade internal carotid artery stenosis

OBJECTIVES

to establish on a national basis whether the diagnostic accuracy of carotid duplex justifies carotid surgery without preoperative angiography.

DESIGN

prospective national multicentre study with 10 participating university and county hospitals.

MATERIAL AND METHODS

one hundred and thirty-four patients, aged 69+/-9 years, were subjected to routine carotid duplex ultrasonography and angiography. The influence of relevant factors on the relation between ultrasonographic and angiographic variables was evaluated using multiple regression analysis. The capacity of carotid ultrasonography to detect internal carotid artery (ICA) stenosis > or =80% was assessed by receiver operating characteristic analysis.

RESULTS

the correlation between peak systolic velocity in ICA (PSV(ICA)) and the angiographic degree of stenosis was strong and significantly influenced only by the applied Doppler angle. Accordingly, the optimal PSV(ICA) cutpoint values for the diagnosis of ICA stenosis > or =80% (ECST method) differed substantially (2.1 and 3.2 m/s) between the two considered angle ranges (0-49 degrees and 50-62 degrees ), the ability to identify high grade ICA stenosis being significantly better at small Doppler angles (0-49 degrees ).

CONCLUSION

ultrasonographic duplex technique identifies high grade ICA stenosis with a high degree of accuracy, which can be further improved by the application of small Doppler angles and the use of angle range specific PSV(ICA) cut-off points.

An FTIR and CD study of the structural effects of G-tract length and sequence context on DNA conformation in solution

Fourier transform infrared (FTIR) and CD spectroscopy have been used to investigate the structural effects of G-tract length and flanking sequence on the conformation of DNA G-tracts in aqueous solution. Particularly, a possible predisposition for A-form features has been probed, since this may be important for protein-DNA interactions. Five different G-tract-containing DNA duplexes have been studied: d[CATGGCCATG](2), d[CATGGGCCCATG](2), d[CATGGGGCCCCATG](2,) d[AGGGGCCCCT](2), and d[TGGGGCCCCA](2). In addition, a DNA duplex lacking a G-tract center was probed (d[CATATGCATATG](2)). The CD and FTIR results show that the G-tract-containing sequences are all in a dominating B-DNA conformation in solution. However, certain spectral variations reflect structural effects of sequence context and G-tract length. CD spectra and FTIR results in the 1800-1500 cm(-1) region show that the base-stacking pattern is greatly affected by the sequence context. The FTIR backbone 1250-1000 cm(-1) region shows the antisymmetric non-bridging phosphate vibration around 1225 cm(-1) in all sequences, demonstrating the overall B-conformation of the backbone. The FTIR sugar 900-800 cm(-1) region shows variable contributions of two bands around 865 cm(-1) and 840 cm(-1), reflecting the N and S-type of sugar pucker. The relative intensities of the 865 cm(-1) and 840 cm(-1) bands have been proposed in the literature to quantitatively yield the contribution of N and S-type of sugar pucker, respectively. This correlation is supported by the present study. Furthermore, the contributions of N-type sugar in the DNA sequences studied indicate structural propensities that agree with trends in reported crystal structures of the same sequences: (1) d[CATGGCCATG](2), for which FTIR shows the lowest contribution of N-type sugar puckering in solution, crystallizes in a B-like conformation; (2) d[AGGGGCCCCT](2), with the highest degree of N-type sugar puckering of all the sequences studied, crystallizes in an A-like conformation; (3) d[CATGGGCCCATG](2), with an N-type contribution intermediate between that of d[CATGGCCATG](2) and d[AGGGGCCCCT](2), crystallizes in an A/B intermediate conformation.

Specific metal-ion binding sites in a model of the P4-P6 triple-helical domain of a group I intron

Divalent metal ions play a crucial role in RNA structure and catalysis. Phosphorothioate substitution and manganese rescue experiments can reveal phosphate oxygens interacting specifically with magnesium ions essential for structure and/or activity. In this study, phosphorothioate interference experiments in combination with structural sensitive circular dichroism spectroscopy have been used to probe molecular interactions underlying an important RNA structural motif. We have studied a synthetic model of the P4-P6 triple-helical domain in the bacteriophage T4 nrdB group I intron, which has a core sequence analogous to the Tetrahymena ribozyme. Rp and Sp sulfur substitutions were introduced into two adjacent nucleotides positioned at the 3' end of helix P6 (U452) and in the joining region J6/7 (U453). The effects of sulfur substitution on triple helix formation in the presence of different ratios of magnesium and manganese were studied by the use of difference circular dichroism spectroscopy. The results show that the pro-Sp oxygen of U452 acts as a ligand for a structurally important magnesium ion, whereas no such effect is seen for the pro-Rp oxygen of U452. The importance of the pro-Rp and pro-Sp oxygens of U453 is less clear, because addition of manganese could not significantly restore the triple-helical interactions within the isolated substituted model systems. The interpretation is that U453 is so sensitive to structural disturbance that any change at this position hinders the proper formation of the triple helix.

Rapid subcutaneous IgG replacement therapy at home for pregnant immunodeficient women

The use of slow or rapid, subcutaneous, IgG (SCIG) infusions in pregnant women with primary antibody deficiencies has been described earlier, though only in single-case reports. In this study, we have evaluated the effect of rapid, SCIG infusions during 11 pregnancies in nine women [six women with common variable immunodeficiency (CVID), two with IgG-subclass deficiencies, and one with combined IgA and IgG2 deficiency]. The weekly infusions were given by the women themselves at a dose of 100 mg/kg/week throughout the pregnancy. No adverse systemic reactions or pronounced, local tissue reactions were recorded during or after the more than 400 infusions. The 11 babies were healthy and were born after 38-42 weeks of uneventful gestation. The concentrations of maternal S-IgG at the time of delivery in the four women with CVID ranged from 6.0 to 8.3 g/L, with cord/maternal S-IgG ratios of 1.0-1.5. The IgG subclasses were transferred to the infants. The SCIG home-therapy regime was greatly appreciated by the women.

Platelet-leukocyte cross talk in whole blood

Thrombosis and inflammation involve complex platelet-leukocyte interaction, the details of which are not fully elucidated. Therefore, we investigated cross talk between platelets and leukocytes in whole blood, under the following physiological conditions: at 37 degrees C, with normal calcium concentrations, and with shear force. Platelet P-selectin and leukocyte CD11b expression were used to monitor platelet and leukocyte activation, respectively, and platelet-leukocyte aggregation (PLA) was analyzed. The leukocyte-specific agonist N:-formyl-methionyl-leucyl-phenylalanine (10(-6) mol/L) increased P-selectin-positive platelets from 2.5+/-0. 1% to 5.1+/-0.6% (P:<0.05). The increase was inhibited by either the platelet-activating factor (PAF) antagonist SR27417, the superoxide anion scavenger superoxide dismutase, the 5-lipoxygenase inhibitor Zileuton, or the 5-lipoxygenase-activating protein inhibitor MK-886, suggesting the involvement of PAF, superoxide anion, and 5-lipoxygenase products in leukocyte-induced platelet activation. The platelet-specific agonist collagen (1 microg/mL) increased leukocyte CD11b expression from 2.94+/-0.52 to 3.81+/-0.58 (P:<0. 05); this was not inhibited by the thromboxane A(2) receptor antagonist ICI 192.605 or the PAF antagonist SR27417. Platelet P-selectin expression induced by N:-formyl-methionyl-leucyl-phenylalanine and leukocyte CD11b expression induced by collagen could be suppressed by glycoprotein IIb/IIIa blockade or P-selectin blockade. This study documents platelet-leukocyte cross talk under conditions that mimic a physiological state and suggests that this involves multiple mediators and mechanisms. Furthermore, new evidence of integrin and selectin involvement in intracellular and intercellular signaling during platelet-leukocyte cross talk is provided.

[Commission of inquiry scrutinized complications of carotid surgery. Half of the complications could be explicable by errors or dubious indications]

As carotid endarterectomy is a prophylactic procedure, it would seem particularly important to analyze complications with an aim to avoiding them. All carotid endarterectomies in Sweden are registered, and all serious complications (death and permanent neurological deficit) are analyzed in detail, classified and discussed within the profession. During the period 1994-1996 the frequency was 4.3 percent (technical causes in 17 percent, contraindications in 8 percent and dubious indications in 21 percent, but correct indication and surgery in 54 percent). Thus, even when conditions are optimal there is a certain price to pay for the prevention of ischemic stroke.

[Multidisciplinary cooperation behind a quality registry for carotid surgery. Good coverage during the first two years]

Carotid surgery prevents recurrent stroke in patients with symptomatic tight stenosis of the carotid artery. The Swedish Carotid Surgery Monitoring Registry seeks to promote selection of patients with significant spontaneous risk for recurrent stroke, with an eye toward expediting evaluation and minimizing surgical complications. To this end, professionals at participating hospitals are informed about their own patient selection and surgery risk in comparison with those in the country as a whole and with set targets. We report the results from the first two years, during which it is estimated that more than half of all patients eligible for carotid surgery in Sweden were included in the registry. Although almost all patients had recent onset of relevant neurological symptoms, less than 60% had a documented tight (80-99% occlusion) stenosis. While the final decision to operate a patient was made within 4 weeks of onset of symptoms for only 18% of the patients the first year, this proportion increased to 33% in the following year. The total incidence of surgery related stroke, myocardial infarct and death was 7.7%, while the incidence of severe stroke, myocardial infarct and death was 3.0%.

Angiographic long-term follow-up data for arteriovenous malformations previously proven to be obliterated after gamma knife radiosurgery

OBJECTIVE

To investigate whether angiograms obtained 2 years after radiosurgery, proving total arteriovenous malformation (AVM) occlusion, represent the final state of treated AVMs and adjacent normal vessels.

METHODS

Angiograms were obtained for 48 patients 5 to 24 years after gamma knife radiosurgery and 4 to 17 years after the AVMs had been proven to be totally occluded after the treatment; changes in normal vessels and signs of recanalization were recorded. Ten of the patients developed clinical symptoms attributable to the AVMs or the treatment after having been declared cured, whereas the other patients did not exhibit symptoms.

RESULTS

There was evidence of AVM nidi at the sites of previously occluded AVMs for two patients and of nidi adjacent to those sites for another two patients. Three of the four recurrent AVMs were associated with hemorrhaging. All patients who experienced hemorrhaging from previously occluded AVMs were < or = 14 years of age at the time of gamma knife radiosurgery. There were signs of segmental narrowing in normal vessels that had been irradiated with high doses (nine patients) or a low dose (one patient). The segmental narrowing decreased with time for four of these patients, was unchanged for four, and increased for two. These vascular changes did not produce clinical symptoms in any of the patients.

CONCLUSION

There is a small possibility that AVMs may reappear after having been totally occluded after radiosurgery, especially in pediatric patients. Segmental narrowing in normal arteries after radiosurgery is a benign condition that rarely progresses and does not produce clinical symptoms.

Optical spectroscopic study of the effects of a single deoxyribose substitution in a ribose backbone: implications in RNA-RNA interaction

The 2'-OH group in the ribose sugars of an RNA molecule plays an important role in guiding tertiary interactions that stabilize different RNA structural motifs. Deoxyribose, or 2'-OH by 2'-H, substitution in both the single-stranded and the duplex part of an RNA backbone has been routinely used to evaluate what role the 2'-OH plays in different tertiary interactions that guide an RNA-RNA contact. A deoxyribose substitution not only has the effect of removing a hydrogen bond donating group, but also introduces a sugar moiety with a preference for C2'-endo pucker in a backbone of predominantly C3'-endo sugars. This study evaluates the effects of a single deoxyribose substitution in both single-stranded and double-helical forms of RNA oligomers. A single-stranded, nonrepetitive 7-mer oligoribonucleotide (7-mer RNA) and four different variants having the same base sequence but with a single deoxyribose sugar at different positions in the strands have been studied by ultraviolet (UV) absorption, circular dichroism (CD), and Fourier transform infrared (FTIR) spectroscopy. Duplexes were formed by association with the complementary strand of the 7-mer RNA. The results show that both RNA and DNA single strands have preorganized conformations with spectral properties resembling those of A- and B-form helices, respectively, with RNA being more heterogeneous than its DNA counterpart. A single deoxyribose substitution perturbs the structure of the RNA backbone, with the effect being more pronounced in the single-stranded than in the duplex structure. The perturbation depends on the position of the 2'-H substitution in the strand.

Flow dependence of forearm noradrenaline overflow, as assessed during mental stress and sodium nitroprusside infusion

OBJECTIVE

To evaluate the influence of blood flow on measurements of regional sympathetic nerve activity by radiotracer methodology ([3H]noradrenaline).

DESIGN

Ten healthy men were studied under two conditions of elevated forearm blood flow: mental stress (Stroop colour word conflict test) and an intra-arterial infusion of sodium nitroprusside.

METHODS

Arterial blood pressure was measured invasively and forearm blood flow with strain-gauge plethysmography. Arterial and venous plasma adrenaline and noradrenaline were measured with high-performance liquid chromatography, and regional and total noradrenaline spillover were calculated.

RESULTS

During mental stress, mean arterial pressure increased by 17%, heart rate by 16 beats/min, forearm blood flow by 117%, while forearm vascular resistance decreased by 44% (P < 0.001 for all). Sodium nitroprusside increased forearm blood flow dose-dependently, but elicited only minor effects on systemic haemodynamics. Mental stress increased arterial plasma noradrenaline by 52% (P < 0.001), and total body noradrenaline spillover by 75% (P < 0.001). During sodium nitroprusside infusion, arterial plasma noradrenaline increased only slightly and total body noradrenaline spillover was unaffected Forearm noradrenaline overflow increased from 5.4 +/- 0.9 to 16.9 +/- 2.6 pmol/min per I (P < 0.001) during mental stress and from 6.6 +/- 0.8 to 16.9 +/- 3.7 pmol/min per I (P < 0.001) during the second dose-step of sodium nitroprusside infusion. By intra-individual comparisons of forearm noradrenaline overflow increases during mental stress and during sodium nitroprusside infusion, with similar forearm blood flow increases, the flow dependence of forearm noradrenaline overflow was estimated. During mental stress, about 60% (median value, range 29-112%) of the increase in forearm noradrenaline overflow was attributed to the increase in forearm blood flow, whereas 40% was considered to reflect increased sympathetic nerve activity.

CONCLUSIONS

There seems to be a considerable flow dependence of the regional overflow of noradrenaline, that is, a component of simple wash-out of noradrenaline from the forearm tissues during vasodilation. However, the present results still indicate that sympathetic nerve activity in the forearm is increased during mental stress, justifying the radiotracer technique for semiquantitative measurements, also during vasodilation.

[Thrombolysis changes the care of stroke]

Thrombolysis using tissue plasminogen activator (tPA) is not the leading strategy in the development of pharmacological treatments for acute ischaemic stroke. The prospect of tPA becoming routine treatment in ischaemic stroke raises several issues the magnitude of the treatment load, the requisite neurological and neuroradiological diagnostic qualifications, identification of local reperfusion effects in the brain, and the pre-hospital and hospital management of acute stroke patients. The results of large randomised trials of intravenous tPA treatment are reviewed in the article, and the current state of our knowledge about interventional thrombolysis is reported. Recruitment for the second European intravenous tPA trail, ECASS II, has recently been completed, and the study findings will be available during the latter half of 1988. In the USA, tPA is already recommended treatment for acute ischaemic stroke within three hours after the onset of symptoms. In Europe, the formulation of guidelines awaits the results of ECASS II.

Evaluation of the post-operative lumbar spine with MR imaging. The role of contrast enhancement and thickening in nerve roots

PURPOSE

Two new signs of lumbar nerve-root affection have been reported in recent years on the basis of MR examinations, namely: thickening in nerve roots; and contrast enhancement in nerve roots. The aim of this study was to assess contrast enhancement in nerve roots in a standardised way, and to evaluate the clinical significance of contrast enhancement and of nerve-root thickening in the symptomatic post-operative lumbar spine.

MATERIAL AND METHODS

A total of 121 patients (who had previously been operated on for lumbar disc herniation) underwent 152 MR examinations, mainly on a 1.5 T system. Focal nerve-root enhancement was identified by visual assessment. Intradural enhancement was also quantified by pixel measurements that compared the affected nerve roots before and after contrast administration. Non-affected nerve roots were used as reference.

RESULTS

Enhanced nerve roots in the dural sac increased at least 40-50% in signal intensity after contrast administration compared to pre-contrast images and also compared to non-affected nerve roots. Intradural nerve-root enhancement was seen in 10% of the patients and focal enhancement in the root sleeve was seen in a further 26%. Nerve-root thickening was seen in 30%. Good correlation with clinical symptoms was found in 59% of the patients with intradural enhancement, in 84% with focal enhancement, and in 86% with nerve-root thickening. The combination of thickening and enhancement in the nerve root correlated with symptoms in 86% of the patients.

CONCLUSION

Nerve-root enhancement (whether focal or intradural) and thickening in the nerve root are significant MR findings in the post-operative lumbar spine. In combination with disc herniation or nerve-root displacement, these two signs may strengthen the indication for repeat surgery. However, root enhancement within 6 months of previous surgery may be a normal post-operative finding.

Attenuation of forearm vasodilator responses to mental stress by regional beta-blockade, but not by atropine

Forearm blood flow during mental stress (Stroop's colour word conflict test) was studied in 18 healthy men before and during regional beta-adrenoceptor blockade (propranolol 0.5 mg), muscarinic receptor blockade (atropine 0.2 mg) and combined blockade, and compared with results obtained in untreated controls. Forearm blood flow was measured with venous occlusion plethysmography, and forearm vascular resistance was calculated. Arterial and venous blood sampling was performed for determination of adrenaline and noradrenaline in plasma. Mental stress increased heart rate, systolic and diastolic blood pressures and forearm blood flow, and lowered the forearm vascular resistance, to the same degree as in our previously studied controls. Neither of the intra-arterially administered drugs had any discernible systemic effects. Beta-blockade increased forearm vascular resistance by 32% and decreased forearm blood flow by 21% compared with unblocked levels during mental stress, whereas forearm vasodilation was maintained throughout the stress test in the control group (P < 0.05). Intra-arterial atropine had no certain effects. Arterial adrenaline levels during mental stress were similar in the receptor-blocked and control groups. In conclusion, the sustained forearm vasodilation during mental stress appears to be partly mediated via beta 2-adrenoceptor stimulation (i.e. by adrenaline), but we obtained no support for a cholinergic vasodilating mechanism.

Blockade of endogenous nitric oxide production results in moderate hypertension, reducing sympathetic activity and shortening bleeding time in healthy volunteers

BACKGROUND

Short-term infusion of NG-monomethyl-L-arginine (L-NMMA) reversibly inhibits endogenous nitric oxide (NO) production in humans. We studied responses to more long-lasting (60 min) infusions, at doses high enough to cause effective inhibition of endogenous NO.

METHODS

Eight healthy volunteers had catheters (pulmonary, arterial and venous) placed. Measurements included hemodynamics, endogenous NO levels in nasal air, bleeding time, and cyclic guanosine monophosphate (cGMP) and catecholamines in plasma. L-NMMA was infused at 0.3 mg.kg-1.min-1 during 30 min, followed by 0.15 (n = 6) or 0.3 (n = 2) mg.kg-1.min-1 during 30 min.

RESULTS

L-NMMA significantly elevated mean arterial pressure by 12 +/- 3%, due to an increase in systemic vascular resistance. Cardiac output decreased by 23 +/- 3%, due to a decrease in stroke volume. Pulmonary vascular resistance (P < 0.05) increased, but mean pulmonary arterial pressure was stable. Forearm vascular resistance (P < 0.05) decreased. Bleeding time was shortened by 31 +/- 4% (P < 0.01). L-NMMA infusion reduced NO concentrations in nasal air by 64 +/- 2% (P < 0.01). Arterial pressure remained elevated and nasal NO remained depressed 90 min after the infusion, whereas most other responses were reversed at that time. Plasma cGMP showed only minor changes. Plasma norepinephrine decreased, suggesting reflexogenic inhibition of sympathetic activity, whereas epinephrine levels were low and stable throughout the experiment.

CONCLUSION

Dosage of (13.5 mg.kg-1 in 60 min) L-NMMA infusion in humans was well tolerated. Pronounced and long-lasting inhibition of endogenous NO production, as evidenced by measurements in nasal air, resulted in unevenly distributed vasoconstriction, a transient decrease in cardiac output, and reflexogenic sympathetic withdrawal. Furthermore, bleeding time was shortened, suggesting platelet activation.

Magnetic resonance imaging of obliterated arteriovenous malformations up to 23 years after radiosurgery

The authors report outcomes in 18 patients with arteriovenous malformations (AVMs) who were treated with gamma knife radiosurgery and in whom magnetic resonance (MR) imaging was obtained a mean of 14 years (range 8-23 years) after treatment and 10 years (range 4-17 years) after confirmed obliteration of the AVM. All patients were asymptomatic after radiosurgery and during the time of the study. In five patients (28%), cyst formation was observed that corresponded to the site of the obliterated AVM. Cyst formation and contrast enhancement on MR imaging could not be statistically correlated to the radiation dose. In 11 (61%) of the 18 patients, contrast enhancement that was not related to a recanalization of the nidus was observed in the target area. In three patients (17%), an increased T2-weighted signal was detected at the site of previous AVM; this was interpreted as gliosis or demyelination, which appeared to be dose dependent. The study illustrates that cyst formation, contrast enhancement, and an increased T2-weighted signal can be observed in asymptomatic patients in the area that was targeted for AVM radiosurgery up to 23 years after the procedure. The report provides new and essential information about long-term effects on normal tissue after radiosurgery and provides a basis for the interpretation of MR studies in the follow up of small AVMs treated by radiosurgery.

Plasma angiotensins and human forearm circulation: effects of sympatho-adrenal activation

Complex interactions appear to exist between the renin-angiotensin system and sympathetic neurotransmission, and sympathetic activity may influence local angiotensin II formation. Arterial and forearm venous plasma levels of angiotensin I and II were therefore studied in 11 healthy males at rest during sympathetic activation elicited by mental stress, and during adrenaline induced vasodilation. Specific assays for angiotensin-(1-8) octapeptide and for angiotensin-(1-10) decapeptide (i.e. angiotensin II and I, respectively), were used. Special precautions to minimize ex vivo formation and/or degradation of angiotensins were employed. Mental stress increased regional noradrenaline overflow three-fold, with a concomitant three-fold increase in forearm blood flow, whereas intravenous adrenaline infusion increased forearm blood flow two-fold and noradrenaline overflow four-old. There was a constant positive veno-arterial concentration difference for angiotensin I under all conditions tested, compatible with local angiotensin I formation. We found no veno-arterial concentration difference for angiotensin II or regional net angiotensin II overflow under the conditions tested. These results in the forearm circulation support previous animal experimental evidence in skeletal muscle and provide no evidence in favour of a de novo formation of angiotensin II in skeletal muscle in vivo during basal conditions. Furthermore, sympathetic nerve stimulation does not seem to enhance angiotensin II generation importantly in this vascular bed.

Sustained forearm vasodilation in humans during mental stress is not neurogenically mediated

To evaluate the possible neurogenic influence on forearm vasodilation during mental stress (Stroop's colour word conflict test), haemodynamic and catecholamine responses were registered in 12 healthy men after axillary blockade. Forearm blood flow was measured with venous occlusion plethysmography and forearm vascular resistance was calculated, with intraarterial blood pressure data. Blood samples for arterial and venous adrenaline and noradrenaline determinations were collected. Basal forearm blood flow increased markedly after axillary blockade, but the relative responses of forearm blood flow and forearm vascular resistance to mental stress were the same as in previously studied unblocked individuals (about +125% and about -40%, respectively). There was no increase in noradrenaline overflow from the forearm during mental stress in the nerve blocked arm. Heart rate and arterial systolic pressure responses as well as catecholamine responses to mental stress were augmented in the nerve blocked group, presumably due to a certain arousal caused by the experimental procedure. Increases in forearm blood flow and decreases in forearm vascular resistance during infusion of adrenaline were similar in the nerve blocked and in the control arm. In conclusion, vasodilation in the forearm during mental stress occurs in the absence of nervous control of the vascular bed. The reactivity of the vascular bed to an exogenous vasodilator (adrenaline) remains unchanged after axillary blockade.

Forearm vasodilator mechanisms during mental stress: possible roles for epinephrine and ANP

The contribution of epinephrine (Epi) to forearm vasodilator responses to mental stress was evaluated in 12 healthy men by comparing hemodynamic and plasma catecholamine responses to mental stress and to intravenous and intra-arterial infusions of epinephrine. Mental stress decreased forearm vascular resistance (FVR) by 45%, increased arterial Epi from 0.23 to 0.44 nmol/l in arterial plasma, and increased forearm norepinephrine overflow. Intra-arterial Epi infusion decreased FVR concentration dependently by up to 43%. Intravenous Epi infusion decreased diastolic arterial pressure and increased heart rate and systolic blood pressure dose dependently. FVR decreased by up to 39% at 4.60 nmol/l Epi in arterial plasma. The average Epi contribution to forearm vasodilation during mental stress was calculated to be between 9 and 30%, depending on if responses to stress were compared with intravenous or intra-arterial Epi infusion. Arterial atrial natriuretic peptide immunoreactivity increased by 23% during stress, supporting a vasodilator influence, whereas vasopressin immunoreactivity was unaffected. Thus secretion of Epi explains only part of the stress-induced forearm vasodilation. Intravenous infusion of Epi appears to activate sympathetic counterregulation.

Intracranial traumatic and non-traumatic haemorrhagic complications of warfarin treatment

An increased referral of patients with anticoagulation related haemorrhages necessitated an analysis of causes and outcome of these complications in a patient group that reflected Swedish therapeutic traditions of anticoagulation treatment. Prospectively, all patients from Stockholm evaluated for warfarin related intracranial haemorrhage occurring during 1987 were analysed and their 6 month outcome recorded. Sixty-eight patients were included. The results of intracranial haemorrhagic complications were catastrophic with a 77% mortality rate. Their incidence was much higher than expected. Forty-one patients had non-traumatic intracerebral haematomas, 1 had a non-traumatic subarachnoid haemorrhage and 26 had traumatic injuries. In the 42 patients with non-traumatic haemorrhages, the indications for anticoagulation were cerebral ischaemic events in a majority (27/42). The remaining 15 patients had different indications for anticoagulation. They also had an increased frequency of hypertension (p < 0.05). In the 26 patients with traumatic haematomas, only 6/26 patients had previous cerebral ischaemic injuries (p < 0.01). Valvular heart prosthesis was their most common indication (11/26) for anticoagulation. Caution in instituting anticoagulation therapy in patients with hypertension or cerebrovascular disease, which is an important indication for anticoagulation in Sweden, is mandatory. Adherence to strict treatment regimens and their continuous reevaluation may help to avoid complications. The finding of more patients than expected with haemorrhagic complications is not compatible with the risk evaluations used to justify anticoagulation therapy in the patient groups studied. Clinical practice must have changed with time, showing that risk evaluations from controlled trials or retrospectively collected clinical data from selected patients are not necessarily applicable for long-term clinical practice.

Determination of cause of death among breast cancer cases in the Swedish randomized mammography screening trials. A comparison between official statistics and validation by an endpoint committee

Between 1976 and 1982, four randomized mammography screening trials started in five screening centres in Sweden, involving 282,777 women (156,911 invited and 125,866 controls) with the aim to study if invitation to screening reduced the breast cancer mortality. An overview of the trials was performed to reduce the confidence intervals for the relative risk estimates. All 1,296 deaths occurring in women with breast cancer detected after randomization were evaluated by an independent endpoint committee (EPC), consisting of four physicians who reviewed collected medical information that was blinded regarding mammography screening. If there was disagreement between the EPC members at the initial individual evaluation the final classification was made at consensus meetings. In only 6.9% (n = 89) of the cases was there disagreement as to whether breast cancer was or was not the underlying cause of death. It was also found that 'breast cancer as underlying cause of death' and 'breast cancer as underlying or contributory cause of death' according to Statistics Sweden resulted in relative risk estimates very similar to those based on the classification by the EPC. The study thus supports the use of official health statistics in the evaluation of randomized breast screening trials in Sweden.

Acute and chronic calcium antagonist treatment elevates sympathetic activity in primary hypertension

Eleven men with mild to moderate primary hypertension were studied at rest and during mental stress before and during intravenous infusion of the calcium antagonist felodipine. Eight of them were restudied during long-term treatment (extended-release felodipine, 10 mg daily). For comparison, 10 normotensive control subjects were studied with the short-term protocol. Heart rate, cardiac output, central cardiovascular pressures, and forearm blood flow were registered. Arterial and venous sampling was performed. Norepinephrine spillovers to arterial plasma and from the forearm were assessed with the use of radiotracer methodology. In the hypertensive patients, felodipine lowered mean arterial blood pressure acutely by 8% (P < .01). Systemic vascular resistance decreased by 22% (P < .001), cardiac output increased by 20% (P < .01), and norepinephrine spillover to arterial plasma increased by 61% (P < .001). Forearm vascular resistance fell by 30% (P < .001), but norepinephrine overflow from the forearm increased by 115% (P < .001). These forearm responses were not seen in normotensive subjects despite similar systemic responses to felodipine infusion. After 8 weeks of treatment, mean arterial pressure decreased to 15% below baseline (P < .001), cardiac output returned toward pretreatment levels, and systemic vascular resistance remained low. Forearm blood flow returned toward basal levels, but forearm vascular resistance remained lowered. Total body and forearm norepinephrine spillover values were as elevated as in the acute situation. The hemodynamic "defense reaction" and the sympathoadrenal response to mental stress were essentially unaffected by felodipine. Stress-induced small elevations of neuropeptide Y-like immunoreactivity persisted during felodipine. Thus, the vasodilatation induced by felodipine elicits sympathetic counterregulation, which persists in the long term with respect to peripheral and total sympathetic activities, despite resetting of the baroreflex control of heart rate.

Optic neuritis: findings on MRI, CSF examination and HLA class II typing in 60 patients and results of a short-term follow-up

Optic neuritis (ON) is a common first manifestation of multiple sclerosis (MS), and examination of patients with ON provides opportunities to study the early clinical stages of MS. This prospective study compares results of brain magnetic resonance imaging (MRI), cerebrospinal fluid (CSF) examinations and HLA-Dw2 phenotyping in 60 consecutive patients with ON. At a median of 17 days after the onset of ON, 69% had oligoclonal IgG bands, and at a median on 79 days after onset, 53% had multiple (> or = 3) white matter lesions on MRI. Subgroup analyses revealed that MRI abnormalities and oligoclonal IgG bands were equally common in patients examined early or late after the onset of ON. Strong correlations were found between the presence of MRI abnormalities and oligoclonal IgG bands. The HLA-Dw2 phenotype was significantly increased in ON patients compared with controls, but also significantly different from a group of MS patients from the same geographical area. A significant relation was found between Dw2 phenotype and oligoclonal IgG bands. During a mean follow-up time of about 2 years, the diagnosis in 17 of the patients changed to clinically definite MS. Initially, 16 of them had oligoclonal IgG bands and 12 had three or more MRI lesions. Both MRI and CSF studies are important diagnostic tools in the workup of ON patients.

Antibiotic prophylaxis in recurrent erysipelas

Recurrences of erysipelas are especially prevalent in patients suffering from local impairment of circulation and intervention might thus be of benefit. Therefore a prospective, randomized, open study was undertaken to evaluate whether daily antibiotic prophylaxis would reduce the risk of recurrence. Patients with venous insufficiency or lymphatic congestion who had suffered two or more episodes of erysipelas during the previous 3 years and were admitted to the Infectious Disease Department at Roslagstull Hospital, Stockholm, Sweden, between November 1988 and November 1991 were included. Fourty patients, 20 on prophylaxis and 20 controls were followed according to a life table analysis during a median time of 15 months. Phenoxymethylpenicillin was prescribed as daily prophylaxis (while erythromycin was given to patients allergic to penicillin). Recurrences of erysipelas appeared to be reduced by daily antibiotic prophylaxis but the effect was not dramatic (p = 0.06). Only in patients with a high recurrence rate continuous antibiotic prophylaxis against erysipelas is indicated.

Cardiovascular and sympatho-adrenal responses to mental stress in primary hypertension

1. Eleven untreated men with mild to moderate primary hypertension and 10 normotensive control subjects were studied at rest and during a mental stress test (Stroop colour word conflict test), which has previously been used in studies of hypertensive patients with regard to non-invasive cardiovascular variables and venous plasma catecholamine concentrations. 2. Heart rate, central cardiovascular pressures, cardiac output (thermodilution) and forearm blood flow (strain gauge plethysmography) were determined. Systemic and forearm vascular resistances were calculated. Arterial and venous plasma adrenaline and noradrenaline concentrations were measured by h.p.l.c., and arterial noradrenaline spillover and noradrenaline overflow from the forearm were assessed by isotope methodology ([3H]noradrenaline). Neuropeptide Y-like immunoreactivity was measured by radioimmunoassay. 3. In hypertensive patients heart rate, arterial blood pressure, cardiac output and forearm blood flow increased by 28%, 13%, 37% and 115%, respectively, and forearm and systemic vascular resistances decreased by 48% and 21%, respectively (P < 0.001 for all responses), during stress. These responses were not different from those of the control group. 4. Arterial noradrenaline spillover rose by 63% and noradrenaline overflow from the forearm rose by 150% in the hypertensive patients in response to mental stress (P < 0.001); no significant group differences could be demonstrated. However, the forearm noradrenaline overflow response to stress tended to be greater in the hypertensive group (P = 0.11). Arterial adrenaline concentrations doubled in both groups (P < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Target delineation in radiosurgery for cerebral arteriovenous malformations. Assessment of the value of stereotaxic MR imaging and MR angiography

A study of 6 selected arteriovenous malformation (AVM) patients was performed to investigate the feasibility of delineating an AVM on MR images and to compare the AVM volume outlined on different images. Conventional stereotaxic angiograms, stereotaxic MR images and MR angiograms using several different pulse sequences were obtained prior to radiosurgery. Treatment plans were made from the conventional stereotaxic angiograms. These plans were then transferred to a separate dose planning computer which displayed the MR images with the superimposed isodose lines. The radiated volumes of AVM and brain tissue were measured from these MR images. Last, an assessment was made of the radiation volume needed for an appropriate treatment of the AVM if the treatment plan was made from the MR images rather than from the conventional stereotaxic angiogram. It was possible to delineate medium and large size AVM nidi on stereotaxic MR images based on an integration of information obtained from various pulse sequences. The estimated volumes of the AVM nidi were found to be larger on the conventional stereotaxic angiograms than on the stereotaxic MR images. Consequently, a dose plan based on a conventional stereotaxic angiogram would result in a higher integral dose to the brain with the same target dose. By using reliable MR information it is expected that the volume of brain exposed to radiation could be decreased and the adverse effects of stereotactic radiosurgery for AVM thereby minimized.

Even the smallest remnant of an AVM constitutes a risk of further bleeding. Case report

A case with an ill-defined arteriovenous malformation in the parieto-occipital region is presented. Open surgery was unsuccessful in removing the AVM totally, and treatment with gamma knife radiosurgery was then attempted. At 14 months after this treatment the AVM was believed to be obliterated. The patient had a new intracranial haemorrhage 59 months after radiosurgery. Renewed angiography showed an obvious AVM outside the previously irradiated area. Retrospective analysis of the angiogram at 14 months after radiosurgery revealed early filling of a draining vein as a sign of residual AVM at this time. Renewed radiosurgical treatment was performed. It is believed that an ill-defined margin, laminar flow, and effects of previous surgery might add to difficulties in a proper visualisation and delineation of an AVM. Further, a small remaining shunt may be overlooked if the angiogram is not carefully analysed or if the angiogram is of inferior quality. It should be stressed that partial or almost total obliteration of an AVM is no protection against rebleeding.

Breast cancer screening with mammography: overview of Swedish randomised trials

Despite encouraging results from screening trials the efficacy of mammography in reducing mortality remains somewhat controversial. Five studies have been done in Sweden. This overview, based on 282,777 women followed for 5-13 years in randomised trials in Malmö, Kopparberg, Ostergötland, Stockholm, and Gothenburg, reveals a 24% (95% confidence interval 13-34%) significant reduction of breast cancer mortality among those invited to mammography screening compared with those not invited. To avoid the potential risk of differential misclassification causes of death were assessed by an independent end-point committee after a blinded review of all fatal breast cancer cases. The mortality reduction was similar, irrespective of the end-point used for evaluation ("breast cancer as underlying cause of death" or "breast cancer present at death"). There was a consistent risk reduction associated with screening in all studies, although the point estimate of the relative risk for all ages varied non-significantly between 0.68 and 0.84. The cumulative breast cancer mortality by time since randomisation was estimated at 1.3 per 1000 within 6 years in the invited group compared with 1.6 in the control group. The corresponding figures after 9 years are 2.6 and 3.3 and after 12 years 3.9 and 5.1. The largest reduction of breast cancer mortality (29%) was observed among women aged 50-69 at randomisation. Among women 40-49 there was a non-significant 13% reduction. In this younger age group cumulative breast cancer mortality was similar in the invited and control group during the first 8 years of follow-up. After 8 years there was a difference in favour of the invited women. There was no evidence of any detrimental effect of screening in terms of breast cancer mortality in any age group. Among women aged 70-74 years screening seems to have had only a marginal impact.