MRI guides diagnostic approach for ischaemic stroke

BACKGROUND AND AIM

Identification of ischaemic stroke subtype currently relies on clinical evaluation supported by various diagnostic studies. The authors sought to determine whether specific diffusion-weighted MRI (DWI) patterns could reliably guide the subsequent work-up for patients presenting with acute ischaemic stroke symptoms.

METHODS

273 consecutive patients with acute ischaemic stroke symptoms were enrolled in this prospective, observational, single-centre NIH-sponsored study. Electrocardiogram, non-contrast head CT, brain MRI, head and neck magnetic resonance angiography (MRA) and transoesophageal echocardiography were performed in this prespecified order. Stroke neurologists determined TOAST (Trial of Org 10172 in Acute Stroke Treatment) classification on admission and on discharge. Initial TOAST stroke subtypes were compared with the final TOAST subtype. If the final subtype differed from the initial assessment, the diagnostic test deemed the principal determinant of change was recorded. These principal determinants of change were compared between a CT-based and an MRI-based classification schema.

RESULTS

Among patients with a thromboembolic DWI pattern, transoesophageal echocardiography was the principal determinant of diagnostic change in 8.8% versus 0% for the small vessel group and 1.7% for the other group (p<0.01). Among patients with the combination of a thromboembolic pattern on MRI and a negative cervical MRA, transoesophageal echocardiography led to a change in diagnosis in 12.1%. There was no significant difference between groups using a CT-based scheme.

CONCLUSIONS

DWI patterns appear to predict stroke aetiologies better than conventional methods. The study data suggest an MRI-based diagnostic algorithm that can potentially obviate the need for echocardiography in one-third of stroke patients and may limit the number of secondary extracranial vascular imaging studies to approximately 10%.

Investigation of non-linear acoustic losses at the open end of a tube

At high acoustic level, non-linear losses at the end of a tube are usually interpreted as the consequence of a jet formation at the tube end resulting in annular vortices dissipating part of the acoustic energy. Previous work has shown that two different regimes may occur. The present work, using particle image velocimetry visualization, lattice Boltzmann method simulation in 2D, and an analytical model, shows that the two different regimes correspond to situations for which the annular vortices remain attached to the tube (low acoustic particle velocity) or detached (high acoustic particle velocity).

Hereditary angioedema and pregnancy: successful management of recurrent and frequent attacks of angioedema with C1-inhibitor concentrate, danazol and tranexamic acid - a case report

Hereditary angioedema (HAE) is a rare but potentially life-threatening condition caused by deficiency of C1 esterase inhibitor. It is characterized by subcutaneous swelling in any part of the skin, gastrointestinal and respiratory tracts. We present the case of a pregnant woman with known HAE that deteriorated during pregnancy with frequent attacks that were managed successfully with danazol, tranexamic acid and regular intravenous administration of C1 esterase inhibitor.

Increasing the use of evidence in health policy: practice and views of policy makers and researchers

Background

Better communication is often suggested as fundamental to increasing the use of research evidence in policy, but little is known about how researchers and policy makers work together or about barriers to exchange. This study explored the views and practice of policy makers and researchers regarding the use of evidence in policy, including: (i) current use of research to inform policy; (ii) dissemination of and access to research findings for policy; (iii) communication and exchange between researchers and policy makers; and (iv) incentives for increasing the use of research in policy.

Methods

Separate but similar interview schedules were developed for policy makers and researchers. Senior policy makers from NSW Health and senior researchers from public health and health service research groups in NSW were invited to participate. Consenting participants were interviewed by an independent research company.

Results

Thirty eight policy makers (79% response rate) and 41 researchers (82% response rate) completed interviews. Policy makers reported rarely using research to inform policy agendas or to evaluate the impact of policy; research was used more commonly to inform policy content. Most researchers reported that their research had informed local policy, mainly by increasing awareness of an issue. Policy makers reported difficulty in accessing useful research syntheses, and only a third of researchers reported developing targeted strategies to inform policy makers of their findings. Both policy makers and researchers wanted more exchange and saw this as important for increasing the use of research evidence in policy; however, both groups reported a high level of involvement by policy makers in research.

Conclusion

Policy makers and researchers recognise the potential of research to contribute to policy and are making significant attempts to integrate research into the policy process. These findings suggest four strategies to assist in increasing the use of research in policy: making research findings more accessible to policy makers; increasing opportunities for interaction between policy makers and researchers; addressing structural barriers such as research receptivity in policy agencies and a lack of incentives for academics to link with policy; and increasing the relevance of research to policy.

Folic acid use in pregnancy and embryo selection

OBJECTIVE

Folic acid supplement use is recommended in pregnancy to reduce the risk of neural tube defect but concerns have been raised that increasing folic acid intake may select for embryos with genotypes that increase disease risk in the offspring. Our aim was to test for this effect.

DESIGN

Observational prospective cohort study.

SETTING

Aberdeen Maternity Hospital.

POPULATION OR SAMPLE

Women born before the introduction of folic acid advice (1970-80) and carrying singleton pregnancies (n = 1234) and their offspring (n = 1083) born after (2001-03).

METHODS

We measured the genotype (MTHFR C677T and A1298C, MTR A2756G, MTRR A66G and TCN G776C) of mothers and their offspring, maternal supplement intake, intake of folate and vitamin B12 from natural foods and maternal blood folate and B12 status at 19 weeks of gestation.

MAIN OUTCOME MEASURES

B vitamin related genotype of the offspring.

RESULTS

There were no significant differences in any of the five genotype frequencies between mothers and their babies. There was no deviation from Hardy-Weinberg equilibrium in either generation and no change in the frequency of doubly homozygous MTHFR variants (677 TT/1298 CC). The genotype of the offspring was not related to maternal periconceptual supplement use, folate intake from foods or plasma and red cell folate measured at 19 weeks of gestation.

CONCLUSIONS

We found no evidence to support the concern that folic acid fortification or supplement use in pregnancy results in selection of deleterious genotypes.

Nasal continuous positive airway pressure from high flow cannula versus Infant Flow for Preterm infants

OBJECTIVE

To compare the feasibility of continuous positive airway pressure (CPAP) support generated by high flow nasal cannula with conventional CPAP for prevention of reintubation among preterm infants with a birth weight of <or=1,250 g.

STUDY DESIGN

Preterm infants were randomized to CPAP generated via high flow cannula or the Infant Flow Nasal CPAP System (VIASYS, Conshohocken, PA, USA) at extubation. Primary outcome was incidence of reintubation within 7 days. Secondary outcomes included change in oxygen use and frequency of apnea and bradycardias postextubation.

RESULTS

Forty neonates were randomized. Twelve of 20 infants randomized to high flow cannula CPAP were reintubated compared to three of 20 using Infant Flow (P=0.003). The high flow cannula group had increased oxygen use and more apneas and bradycardias postextubation.

CONCLUSIONS

CPAP delivered by high flow nasal cannula failed to maintain extubation status among preterm infants <or=1,250 g as effectively as Infant Flow CPAP.

Absence of conception after caesarean section: voluntary or involuntary?

BACKGROUND

Women who deliver by caesarean section have been shown to be less likely to have a subsequent pregnancy. It is not clear whether this is due to a direct effect of the procedure on future fertility or due to deliberate avoidance of a future pregnancy.

OBJECTIVE

To investigate whether absence of conception following caesarean section is voluntary or involuntary.

DESIGN

Follow up of a population-based retrospective cohort.

SETTING

Grampian region, Scotland.

POPULATION

Women who had no further viable pregnancies within 5 years of an initial delivery.

METHODS

Cases included women who delivered their first child by caesarean section between 1980 and 1995 but had no further viable pregnancies by December 2000. Controls included women who delivered their first child during the same period, by means of either spontaneous vaginal delivery (SVD) or instrumental vaginal delivery (IVD), and who had no further viable pregnancies by December 2000. Eligible women were identified from the Aberdeen Maternity and Neonatal Databank (AMND) and sent postal questionnaires to determine the extent to which not conceiving after first delivery was voluntary and the reasons for avoiding further pregnancies. Characteristics of the different mode of delivery groups were compared using univariate techniques.

MAIN OUTCOME MEASURES

Extent to which absence of conception following an initial delivery by caesarean section is voluntary.

RESULTS

Questionnaires were returned by 3204 (60%) of 5300 women identified from the AMND. Of these, 1675 women had not conceived at all during the follow-up period (median duration = 13 years). Absence of conception was voluntary in 488 (69%; 95% CI 66-73%) women following caesarean section, 340 (71%; 95% CI 67-76%) following SVD and 354 (72%; 95% CI 68-76%) following IVD. Few women considered seeking fertility treatment (caesarean section = 72 [10%], SVD = 50 [11%], IVD = 39 [8%]). Of the women who decided to delay or avoid a further pregnancy, fewer women who delivered by SVD reported that the birth experience influenced their decision (caesarean section = 163 [32%], SVD = 67 [18%], IVD = 136 [35%]; P < 0.001).

CONCLUSIONS

Irrespective of mode of delivery, not conceiving following the birth of the first child is mainly voluntary. The experience of the previous birth is one of several factors affecting women's decisions to avoid a subsequent pregnancy.

Numerical simulation of particle motion in an ultrasound field using the lattice Boltzmann model

In this paper we investigate the motion of small particles suspended in a fluid through which an ultrasound field is propagating. The application of the lattice Boltzmann model to this problem is considered using a two dimensional model. Particles in an ultrasound field are observed to move with a mean particle motion. Further, the time-averaged force on a fixed cylinder is computed and found to be in good agreement with a theoretical expression for the radiation force. Simulations are performed with a single particle, although the approach can equally be applied for a larger number of particles.

Ponderal index is a poor predictor of in utero growth retardation

OBJECTIVE

To evaluate the usefulness of ponderal index (PI) and related indices of weight and length in identifying asymmetric growth, body thinness and organ asymmetry associated with IUGR.

DESIGN

Cross sectional study.

SETTING

Aberdeen Maternity Hospital.

POPULATION

The population includes term (>/=37 weeks) singleton live births (n= 53,934) between 1986 and 1996, ultrasound measurements in 2522 pregnancies, 712 unselected term pregnancies in 1979/1980 and stillbirths (24-36 weeks) between 1986 and 1995 where the fetus was diagnosed as suffering from acute (n= 73) or chronic (n= 30) anoxic death.

METHODS

The strength of association between direct measures of IUGR and various indices of weight and length was determined by linear and multiple stepwise linear regression.

MAIN OUTCOME MEASURES

Weight, length, PI and skinfold thicknesses (triceps, biceps, flank thighs, back) were measured at birth. Abdominal circumference, biparietal diameter and femur length were measured by ultrasound at >/=37 weeks. Ratio of liver, heart and kidney to brain were measured in stillbirths.

RESULTS

Weight alone was a better predictor of skinfold thickness, abdominal circumference and the ratio of abdominal circumference to biparietal diameter than weight divided by length raised to the power 1, 2, 3 (PI), 4 or 5. The inclusion of gestational age made little difference to the predictive ability of weight for these full term births. Weight, but not PI, was significantly different between the two groups of stillborn fetuses (chronic and acute), which had significantly different (P < 0.001) organ ratios.

CONCLUSION

Body weight alone was a better predictor of anthropometric ratios, organ asymmetry and measures of thinness at birth thought to be associated with IUGR than the PI. The inclusion of a length term generally reduced the predictive ability with the highest powers resulting in the poorest prediction.

Relationship between birth weight and adult lung function: controlling for maternal factors

BACKGROUND

There is conflicting evidence on the "fetal origins hypothesis" of association between birth weight and adult lung function. This may be due to failure to control for confounding maternal factors influencing birth weight. In the present study access to birth details for adults aged 45-50 years who were documented as children to have asthma, wheezy bronchitis, or no respiratory symptoms provided an opportunity to investigate this association, controlling for maternal factors.

METHODS

In 2001 the cohort was assessed for current lung function, smoking status, and respiratory symptoms. Birth details obtained from the Aberdeen Maternity and Neonatal Databank recorded birth weight, gestation, parity, and mother's age and height.

RESULTS

381 subjects aged 45-50 years were traced and tested for lung function; 323 (85%) had birth details available. A significant linear trend (p<0.01) was observed between birth weight and current forced expiratory volume in 1 second (FEV(1)) and forced vital capacity (FVC) values (adjusted for height, age, sex, weight, deprivation category (Depcat), childhood group, and smoking status). This trend remained significant after adjusting birth weight for gestation, parity, sex, mother's height and weight (p = 0.01). The relationship between birth weight and FEV(1) and FVC remained significant when adjusted for smoking history. There was no association between birth weight and current wheezing symptoms.

CONCLUSION

There is a positive linear trend between birth weight, adjusted for maternal factors, and lung function in adulthood. The strength of this association supports the "fetal origins hypothesis" that impairment of fetal growth is a significant influence on adult lung function.

Prothrombotic genotypes are not associated with pre-eclampsia and gestational hypertension: results from a large population-based study and systematic review

DNA samples collected as part of a large population-based case-control study were genotyped to examine the associations of five prothrombotic gene polymorphisms with pre-eclampsia (PE) and gestational hypertension (GH). The polymorphisms studied were: G1691A in Factor V (Factor V Leiden; FVL), prothrombin G20210A, methylenetetrahydrofolate reductase (MTHFR) C677T, plasminogen activator inhibitor-1 4G/5G and the platelet collagen receptor alpha2beta1 C807T. A group of 404 women who developed PE were retrospectively compared with 303 women with GH and 164 control women. The frequency of genotypes did not differ significantly between cases of PE or GH and controls for any of the five polymorphisms studied. We conclude that these prothrombotic genotypes are not associated with the development of PE or GH in our population. The systematic review supports our conclusion, for all but cases of severe disease. which appear to be associated with FVL and, to a lesser extent, MTHFR C677T. There is little value in antenatal screening for prothrombotic polymorphisms to predict the development of pre-eclampsia or gestational hypertension.

Assessment of hand-arm vibration syndrome in a northern Ontario base metal mine

The objective of this study was to determine the prevalence of hand-arm vibration syndrome (HAVS) in 617 workers at a base metal mine in northern Ontario. Workers who were employed at the mine between the years 1989 and 1994 and who continued to live within a 100 km radius of the mine were sent a self-reported questionnaire to identify individuals with possible vibration-induced symptoms in their upper extremities. Of the 162 workers who attended the medical examination, 50% were diagnosed with HAVS, 26% had other diagnoses with some workers having multiple afflictions e.g., both HAVS and carpal tunnel syndrome (CTS). No vibration-induced symptoms were reported in 35% of the workers who were clinically normal. The study was designed to educate, advise, and to make recommendations on the prevention of HAVS. Ongoing commitments to technological improvements, mandatory and regular rest periods, and continuing educational sessions on the syndrome should help to reduce the prevalence of this disease.

Risk factors for sporadic cases of Escherichia coli O157 infection: the importance of contact with animal excreta

To determine environmental risk factors for sporadic E. coli O157 infection in Scotland we undertook a prospective, matched case-control study between 1 October 1996 and 31 March 1999. One hundred and eighty-three cases and 545 matched controls were recruited. Contact with animal faeces (OR = 3.65; 95% CI 1.81, 7.34: P < 0.0005) and likely contact with animal faeces (OR = 4.8; 95% CI 2.42, 9.48; P < 0.0005) emerged as strong risk factors for infection. Certain exposures (mainly food-related) were inversely associated with infection i.e. were statistically protective. Most striking was the consumption of bottled water (OR = 0.28; 95% CI 0.15, 0.52; P < 0.0005). Transmission of E. coli O157 does not occur simply through contaminated food. Members of the public need to be aware of the potential for acquiring E. coli O157 through contamination of the environment with animal faeces so that they may take measures to mitigate their risk.

Can obstetric complications explain the high levels of obstetric interventions and maternity service use among older women? A retrospective analysis of routinely collected data

OBJECTIVE

To determine whether the higher levels of obstetric intervention and maternity service use among older women can be explained by obstetric complications.

DESIGN

A retrospective analysis of routinely collected data from the Aberdeen Maternity and Neonatal Databank.

PARTICIPANTS

All residents of Aberdeen city district delivering singleton infants at the Maternity Hospital 1988-1997 (28,484 deliveries).

MAIN OUTCOME MEASURES

Odds ratios for each intervention in older maternal age groups compared with women aged 20-29. Interventions considered include obstetric interventions (induction of labour, augmentation, epidural use, assisted delivery, caesarean section) and raised maternity service use (more than two prenatal scans, amniocentesis, antenatal admission to hospital, admission at delivery of more than five days, infant resuscitation, and admission to the neonatal unit).

METHODS

Logistic regression was used to investigate the association between maternal age and the incidence of interventions. The odds ratios for each intervention were then adjusted for relevant obstetric complications and maternal socio-demographic characteristics.

RESULTS

Levels of amniocentesis, caesarean section, assisted delivery, induction, and augmentation (in primiparae) are all higher among older women. Maternity service use also increases significantly with age: older women are more likely to have an antenatal admission, more than two scans, a hospital stay at delivery of more than five days, and have their baby admitted to a neonatal unit. Controlling for relevant obstetric complications reveals several examples of effect modification, but does not eliminate the age effect for most interventions in most groups of women.

CONCLUSIONS

Higher levels of intervention among older women are not explained by the obstetric complications we considered.