[The evaluation of pharmacological drugs, medical devices, and non-pharmacological or public health interventions: Experimental design limitations. Moving towards new methods?]

In the field of health, evidence-based medicine and associated methods like randomised controlled trials (RCTs) have become widely used. RCT has become the gold standard for evaluating causal links between interventions and health results. Originating in pharmacology, this method has been progressively expanded to medical devices, non-pharmacological individual interventions, as well as collective public health interventions. Its use in these domains has led to the formulation of several limits, and it has been called into question as an undisputed gold standard. Some of those limits (e.g. confounding biases and external validity) are common to these four different domains, while others are more specific. This paper describes the different limits, as well as several research avenues. Some are methodological reflections aiming at adapting RCT to the complexity of the tested interventions, and at overcoming some of its limits. Others are alternative methods. The objective is not to remove RCT from the range of evaluation methodologies, but to resituate it within this range. The aim is to encourage choosing between different methods according to the features and the level of the intervention to evaluate, thereby calling for methodological pluralism.

MRI of acute osteomyelitis in long bones of children: Pathophysiology study

INTRODUCTION

The classic pathophysiology of acute osteomyelitis in children described by Trueta has a metaphyseal infection as the starting point. This hypothesis was recently brought into question by Labbé's study, which suggested a periosteal origin. Thus, we wanted to study this disease's pathophysiology through early MRI examinations and to look for prognostic factors based on abnormal findings.

MATERIAL AND METHODS

This was a prospective, multicentre study that included cases of long bone osteomyelitis in children who underwent an MRI examination within 7days of the start of symptoms and within 24hours of the initiation of antibiotic therapy. We also collected clinical, laboratory and treatment-related data.

RESULTS

Twenty patients were included, including one with a bifocal condition. The lower limb was involved in most cases (19/21). Staphylococcus aureus was found most frequently. Metaphyseal involvement was present in all cases. No isolated periosteal involvement was found in any of the cases. No prognostic factors were identified based on the various abnormal findings on MRI.

CONCLUSION

Our study supports the metaphyseal origin of acute osteomyelitis in children.

LEVEL OF EVIDENCE

II.

The early life nutritional environment and early life stress as potential pathways towards the metabolic syndrome in mid-life? A lifecourse analysis using the 1958 British Birth cohort

Background

Lifecourse studies suggest that the metabolic syndrome (MetS) may be rooted in the early life environment. This study aims to examine the pathways linking early nutritional and psychosocial exposures and the presence of MetS in midlife.

Methods

Data are from the National Child Development Study including individuals born during 1 week in 1958 in Great Britain and followed-up until now. MetS was defined based on the National Cholesterol Education Program Adult Treatment Panel III classification. Mother’s pre-pregnancy body mass index (BMI) was used as a proxy of the early nutritional environment and Adverse Childhood Experiences (ACE) as a proxy for early psychosocial stress. Socioeconomic characteristics, pregnancy and birth conditions were extracted as potential confounders. Adult health behaviors, BMI, socioeconomic environment and psychological state were considered as mediating variables.

Multivariate models were performed by including variables sequentially taking a lifecourse approach.

Results

37.5 % of men and 19.8 % of women had MetS. Participants with an obese/overweight mother presented a higher risk of MetS than those whose mother had a normal pre-pregnancy BMI. Men exposed to two ACE or more, and women exposed to one ACE, were more at risk of MetS compared to unexposed individuals. After including confounders and mediators, mother’s pre-pregnancy BMI was still associated with MetS in midlife but the association was weakened after including participant’s adult BMI. ACE was no longer associated with MetS after including confounders in models.

Conclusions

The early nutritional environment, represented by mother’s pre-pregnancy BMI, was associated with the risk of MetS in midlife. An important mechanism involves a mother-to-child BMI transmission, independent of birth or perinatal conditions, socioeconomic characteristics and health behaviors over the lifecourse. However this mechanism is not sufficient for explaining the influence of mother’s pre-pregnancy BMI which implies the need to further explore other mechanisms in particular the role of genetics and early nutritional environment. ACE is not independently associated with MetS. However, other early life stressful events such as emergency caesarean deliveries and poor socioeconomic status during childhood may contribute as determinants of MetS.

The results of seton drainage combined with anti-TNFα therapy for anal fistula in Crohn's disease

AIM

Combined infliximab and sphincter-sparing surgery can be effective in perianal fistula associated with Crohn's disease (CD). This study aimed to assess the efficacy of local surgery combined with infliximab on sustained fistula closure and to identify predictive factors for response after this combined treatment.

METHOD

Between 2000 and 2010, 81 patients with fistulising perianal CD were included in this observational study. Drainage with a loose seton was followed by infliximab therapy. The primary end-points were the rate of complete fistula closure and time required for this to occur.

RESULTS

The fistula was complex in 71 (88%) of the 81 patients. Local proctological surgery was carried out in 77 (95%), including seton drainage in 62 (80.5%) of these. This was continued for a median duration of 3.8 months and the patient then received infliximab therapy. The median follow-up after treatment was 64 months (2-263). Initial complete closure of the fistula occurred in 71 (88%) cases at a median interval of 12.4 months (1-147) from the start of treatment. Recurrence was observed in 29 (41%) patients at a median interval of 38.5 months (2-48) from the start of treatment. They were treated again with combined treatment with successful closure in 19 (65.5%) patients. The total rate of closure of the fistula was 75.3%. Female gender, anal stenosis, rectovaginal and complex fistula formation were factors independently associated with failure of combined treatment.

CONCLUSION

Seton drainage for several months combined with infliximab therapy is effective in closing the fistula in 75% of patients with complex perianal fistula formation associated with CD.

Validation of a new tool: the calorie intake tool, to easily estimate the energy intake of diseased aged patient

OBJECTIVE

The aim of the study was to validate the Calorie Intake Tool (CIT), a new tool to estimate energy intake.

DESIGN, SETTING AND PATIENTS

100 patients older than 75 were randomly selected in seven geriatric units at Toulouse University Hospital.

MEASUREMENTS

Energy intake was calculated for each subject with the CIT and by weighing the food consumed.

RESULTS

Total calorie intake did not differ significantly between the two methods, 1318 ± 586 for CIT and 1353 ± 625 for food weighing. The Intraclass Correlation coefficient (ICC) was higher than 0.89 for total calorie intake and the Bland and Altman analysis was consistent with these results and showed a bias for high calorie intake (mean error 35 ± 420 kcal).

CONCLUSION

The study shows that the CIT for the evaluation of calorie intake in elderly diseased patients is valid against the reference method (weighing the food consumed).

Long-term carcinologic results of advanced esthesioneuroblastoma: a systematic review

Surgical resection followed by radiotherapy can be considered like the optimal treatment modality for limited esthesioneuroblastoma. However, therapeutic management of locally advanced tumors remains a challenge. The aim of our study was to access and compare the oncologic results of the different treatment modalities in advanced esthesioneuroblastoma. We performed a systematic review using the Medline, and Cochrane database in accordance with PRISMA criteria and included all the cases of advanced esthesioneuroblastoma published between 2000 and 2013. We also retrospectively included 15 patients with an advanced esthesioneuroblastoma managed at our tertiary care medical center. Long-term survival rates defined as the time from diagnosis or randomization to the date of death or last follow-up were evaluated for each treatment with Kaplan-Meier survival curve analyses. 283 patients have been included. The mean follow-up was 78 months. Five-year highest survival rates were obtained in patients treated by surgery associated with radiotherapy. Ten-year highest survival rates were obtained in patients treated by the association of surgery, radiotherapy and chemotherapy (p = 0.0008). Within the surgical group, 5-year highest survival rates were obtained in patients treated by endoscopic resection (p = 0.003). Surgical resection combined with radiotherapy offers the gold standard of care. Adjuvant chemotherapy seems to improve the long-term survival in patients with locally advanced esthesioneuroblastoma. Endoscopic resection in advanced tumors should be discussed on a case-by-case basis.

The lateral view head-neck index (LVHNI): a diagnostic tool for the sequelae of slipped capital femoral epiphysis

INTRODUCTION

It is a well-known fact that slipped capital femoral epiphysis (SCFE) is one of the causes of premature hip osteoarthritis and anterior femoroacetabular impingement. But there are no reliable, published diagnostic methods to measure the residual deformity of slipped capital femoral epiphysis. We propose using the lateral view head-neck index (LVHNI) measurement on a specific lateral X-ray view of the hip for this purpose.

HYPOTHESIS

The LVHNI can detect and quantify the posterior translation of the femoral head and this index can be measured reliably.

MATERIALS AND METHODS

A prospective radiography study was performed by three observers. The hip X-rays of patients who were being treated by arthroplasty for hip osteoarthritis (total hip replacement or hip resurfacing) between January 2010 and December 2011 were analyzed. The LVHNI, which quantifies the posterior translation of the femoral head, was measured on a lateral view of the hip in 45° flexion/45° abduction/30° external rotation. The presence of a pistol grip deformity on A/P X-rays was also assessed.

RESULTS

The analysis was performed on 131 hips in 120 patients having an average age of 61 years (range 37-91). The chosen LVHNI threshold of 9% resulted in a sensitivity of 89.1% (95% CI: 78.8%-95.5%) and a specificity of 82.4% (95% CI: 71.2%-89.7%) for detecting the presence of a pistol grip deformity. Twenty percent of the hips with no visible deformity on A/P X-rays had a pathological index value. The inter-observer reproducibility was good for the LHNI [intraclass correlation coefficient (ICC): 0.61; 95% CI: 0.51-0.71] and for detecting a pistol grip deformity (ICC: 0.74; 95% CI: 0.62-0.85). The intra-observer reproducibility was excellent for the LHNI (ICC: 0.78; 95% CI: 0.57-0.88) and the pistol grip deformity (ICC: 0.85; 95% CI: 0.74-0.92).

CONCLUSION

The LVHNI is a reliable and reproducible tool to identify deformities secondary to SCFE on specific lateral femoral neck X-rays. If the index value is greater than 9%, SCFE sequelae may be present. In addition, this study showed that 20% of hips with normal A/P X-rays had a pathological index.

LEVEL OF EVIDENCE

Level IV, prospective diagnostic study without control group.

Effect of voxel size on the accuracy of 3D reconstructions with cone beam CT

OBJECTIVES

The various types of cone beam CT (CBCT) differ in several technical characteristics, notably their spatial resolution, which is defined by the acquisition voxel size. However, data are still lacking on the effects of voxel size on the metric accuracy of three-dimensional (3D) reconstructions. This study was designed to assess the effect of isotropic voxel size on the 3D reconstruction accuracy and reproducibility of CBCT data.

METHODS

The study sample comprised 70 teeth (from the Institut d'Anatomie Normale, Strasbourg, France). The teeth were scanned with a KODAK 9500 3D® CBCT (Carestream Health, Inc., Marne-la-Vallée, France), which has two voxel sizes: 200 µm (CBCT 200 µm group) and 300 µm (CBCT 300 µm group). These teeth had also been scanned with the KODAK 9000 3D® CBCT (Carestream Health, Inc.) (CBCT 76 µm group) and the SCANCO Medical micro-CT XtremeCT (SCANCO Medical, Brüttisellen, Switzerland) (micro-CT 41 µm group) considered as references. After semi-automatic segmentation with AMIRA® software (Visualization Sciences Group, Burlington, MA), tooth volumetric measurements were obtained.

RESULTS

The Bland-Altman method showed no difference in tooth volumes despite a slight underestimation for the CBCT 200 µm and 300 µm groups compared with the two reference groups. The underestimation was statistically significant for the volumetric measurements of the CBCT 300 µm group relative to the two reference groups (Passing-Bablok method).

CONCLUSIONS

CBCT is not only a tool that helps in diagnosis and detection but it has the complementary advantage of being a measuring instrument, the accuracy of which appears connected to the size of the voxels. Future applications of such measurements with CBCT are discussed.

DNA replication stress response involving PLK1, CDC6, POLQ, RAD51 and CLASPIN upregulation prognoses the outcome of early/mid-stage non-small cell lung cancer patients

Lung cancer is the leading cause of cancer deaths worldwide. Clinical staging classification is generally insufficient to provide a reliable prognosis, particularly for early stages. In addition, prognostic factors are therefore needed to better forecast life expectancy and optimize adjuvant therapeutic strategy. Recent evidence indicates that alterations of the DNA replication program contribute to neoplasia from its early stages and that cancer cells are frequently exposed to endogenous replication stress. We therefore hypothesized that genes involved in the replication stress response may represent an under-explored source of biomarkers. Expressions of 77 DNA replication-associated genes implicated in different aspects of chromosomal DNA replication, including licensing, firing of origins, elongation, replication fork maintenance and recovery, lesion bypass and post-replicative repair were determined in primary tumors and adjacent normal tissues from 93 patients suffering from early- or mid-stage non-small cell lung cancer (NSCLC). We then investigated a statistically significant interaction between gene expressions and survival of early-stage NSCLC patients.The expression of five genes, that is, POLQ, PLK1, RAD51, CLASPIN and CDC6 was associated with overall, disease-free and relapse-free survival. The expression levels are independent of treatment and stage classification. Except RAD51, their prognostic role on survival persists after adjustment on age, sex, treatment, stage classification and conventional proliferation markers, with a hazard ratio of 36.3 for POLQ (95%CI 2.6–517.4, P=0.008), 23.5 for PLK1 (95%CI 1.9–288.4, P=0.01), 20.7 for CLASPIN (95%CI 1.5–275.9, P=0.02) and 18.5 for CDC6 (95%CI 1.3–267.4, P=0.03). We also show that a five-gene signature including POLQ, PLK1, RAD51, CLASPIN and CDC6 separates patients into low- and high-risk groups, with a hazard ratio of 14.3 (95% CI 5.1–40.3, P<0.001). This ‘replication stress' metamarker may be a reliable predictor of survival for NSCLC, and may also help understand the molecular mechanisms underlying tumor progression.

Estimating controlled direct effects in the presence of intermediate confounding of the mediator–outcome relationship: Comparison of five different methods

In mediation analysis between an exposure X and an outcome Y, estimation of the direct effect of X on Y by usual regression after adjustment for the mediator M may be biased if Z is a confounder between M and Y, and is also affected by X. Alternative methods have been described to avoid such a bias: inverse probability of treatment weighting with and without weight truncation, the sequential g-estimator and g-computation. Our aim was to compare the usual linear regression adjusted for M to these methods when estimating the controlled direct effect between X and Y in the causal structure and to explore the size of the potential bias. Estimations were computed in several simulated data sets as well as real data. We observed an increased bias of the controlled direct effect estimation using linear regression adjusted for M for larger effects of X on M and larger effects of Z on M. The sequential g-estimator and g-computation gave unbiased estimations with adequate coverage values in every situation studied. With continuous exposure X and mediator M, inverse probability of treatment weighting resulted in some bias and less satisfactory coverage for large effects of X on M and Z on M.

[Hypertension and perceived material insecurity in a disadvantaged Caribbean population]

OBJECTIVE

To assess the relationship between hypertension and perceived material insecurity in a disadvantaged Caribbean population.

PATIENTS AND METHODS

We used data from a cross-sectional study involving 2420 disadvantaged subjects aged 18-69 years, included consecutively at three Guadeloupian health centers. Hypertension was diagnosed over two consultations with a total of six blood pressure measurements. Perceived material insecurity was assessed using a closed-ended question.

RESULTS

The prevalence of hypertension was estimated at 17.7% among subjects who believed their material situation would improve in the future, at 28.2% among those who believed it would remain the same, and at 43.3% among those who believed it would deteriorate. A multivariate logistic regression analysis showed that hypertension risk more than doubled (OR: 2.35 - P: 0.002) among subjects who believed that their material situation would deteriorate in the future compared to those who believed that their situation would improve, with no significant sex-related differences. This relationship was especially strong among subjects aged 40 years or more (OR: 3.30 - P<10(-3)), and among subjects with low education level (OR: 3.81 - P: 0.003), but was independent of the other tested variables.

CONCLUSION

In this disadvantaged population, perceived material insecurity is a psychosocial factor strongly associated with hypertension, independently of subjects' risk behaviors. Subjects aged 40 years or more and subjects with a low education level seem the most vulnerable.

Gene expression signature of advanced pancreatic ductal adenocarcinoma using low density array on endoscopic ultrasound-guided fine needle aspiration samples

AIMS

The purpose of this study was to investigate the clinical feasibility and utility of low-density array analysis on samples obtained from endoscopic ultrasound-guided fine needle aspiration biopsy in locally advanced and/or metastatic pancreatic ductal adenocarcinoma and chronic pancreatitis.

PATIENTS AND METHODS

In this prospective multicenter study, we quantified candidate gene expression in biopsies sampled from 44 locally advanced and/or metastatic pancreatic carcinoma and from 17 pseudotumoural chronic pancreatitis using dedicated low-density array microfluidic plates.

RESULTS

We first demonstrated that 18S gene expression is stable and comparable in normal pancreas and pancreatic cancer tissues. Next, we found that eight genes (S100P, PLAT, PLAU, MSLN, MMP-11, MMP-7, KRT7, KRT17) were significantly over expressed in pancreatic cancer samples when compared to pseudotumoural chronic pancreatitis (p value ranging from 0.0007 to 0.0215): Linear discriminative analysis identified S100P, PLAT, MSLN, MMP-7, KRT7 as highly explicative variables. The area under receiver operating curve establishes the clinical validity of the potential diagnostic markers identified in this study (values ranging from 0.69 to 0.76). In addition, combination of S100P and KRT7 gave better diagnosis performances (Area Under Receiver Operating Curve 0.81, sensitivity 81%, specificity 77%).

CONCLUSION

We demonstrate that molecular studies on EUS-guided FNA material are feasible for the identification and quantification of markers in PDAC patients diagnosed with non-resectable tumours. Using low-density array, we isolated a molecular signature of advanced pancreatic carcinoma including mostly cancer invasion-related genes. This work stems for the use of novel biomarkers for the molecular diagnosis of patient with solid pancreatic masses.

Use of a risk analysis method to improve care management for outlying inpatients in a university hospital

OBJECTIVE

To improve the quality of care provided for inpatients outlying in inappropriate wards of a teaching hospital because of lack of vacant beds in appropriate specialty wards.

METHODS

A multidisciplinary team consisting of hospital doctors, nurses and managers performed a prospective risk analysis of the process of care provided for outlying patients during their hospitalisation. The design of the study was Failure Modes, Effects and Criticality Analysis (FMECA). Failure modes were defined and classified according to their criticality, in order to identify priority actions for improvement. Criticality indices were calculated by multiplying occurrence, severity and detection scores.

RESULTS

Measures for improvement indicated by the most critical failure modes were the identification of specialist doctors in appropriate specialty wards to be responsible for the care of outlying patients falling within their sphere of competence; the identification of a nurse coordinator in each department to improve communication between the emergency department, appropriate specialty wards and outlying wards; the standardisation of medical records throughout the whole hospital to ensure better traceability and access to information.

CONCLUSIONS

Using FMECA, we were able to identify the most critical failure modes of the complex process of care provided for outlying patients and to suggest subsequent improvement measures. Follow-up indicators were defined to assess implementation.

[Cochlear implants in elderly: performance outcomes in the long term]

OBJECTIVES

To study and compare the evolving capacities of speech discrimination with cochlear implants in older patients compared to patients implanted at a younger age.

METHODOLOGY

A retrospective study comparing a group of 52 patients aged over 65 with a control group of 58 patients aged between 30 and 50 years, followed for 5 years after implantation. We analyzed and compared the evolution of speech discrimination in silence (disyllabic words, sentences) and noise (sentences, S/N ratio: +10 dB) after implantation.

RESULTS

In the group of elderly patients, the speech discrimination in silence remains stable over time (for disyllabic words, score at 6 months: 72.8 +/- 20.2%; score at 5 years: 73.7% +/- 19.7). Discrimination in noise tends to improve (mean score at 6 months: 70.5% +/- 21.5; score at 5 years: 76.9% +/- 16.9). The results obtained are in silence are comparable to the results of the group of patients aged between 30 and 50. In noise, their performance remains lower than the control group (mean differences between scores: -10.8; confidence interval at 95%: -17.9, -5.3).

CONCLUSION

The cochlear implant is effective over the long term in elderly patients, for speech discrimination in quiet and in noise. In silence, their performance is comparable to younger patients with implants.

Surgical-site infections and surgery of the salivary glands

OBJECTIVES

To determine the surgical-site infection (SSI) incidence rate targeted on salivary gland surgery over a 2-year period (from January 2007 to December 2008). Then identify any risk factors associated with SSI in all the patients operated with no antibiotic prophylaxis in accordance with French Anesthesiology Society guidelines.

POPULATION AND METHODS

Ninety-three patients were operated during the standard SSI surveillance period. A case-control (one case for five controls) study was then conducted aiming to identify risk factors.

RESULTS

The SSI incidence rate was 9.7%. The case-control study failed to identify any relevant risk factor with univariate analysis.

CONCLUSION

As no risk factors could be identified, we suggest that surgical antibioprophylaxis could be relevant in salivary glands surgery and should be evaluated in this setting.

[Construction and validation of a quantitative assessment of speech intelligibility for speech disorders]

Intelligibility of speech measure is based on the perception of the listeners.

OBJECTIVE

The aim of this study was the construction and the validation of a quantitative test of speech disorders severity allowing the the follow up and the measure of management impact.

MATERIAL AND METHOD

After a first step of construction and feasibility, the psychometric validation was performed. 37 patients with a speech disorder and 13 normal subjects were recorded. The reference was the global score obtained by reading a text. The whole recordings were scored by a panel of 5 judges. The test was composed by a automatic series of words (the months of the year) with a phono-orthographic score, the semantic transcription of a list of words and sentences, a qualitative score of spontaneous speech obtained by the description of a photography.

RESULTS

The intra and inter judges reliability are correct (intraclasse coefficient of 0.97 and 0.98). The different parts of the test are well correlated to the reference proof (r = 0.75 to 0.82). Chronbach alpha is 0.98, the limits of agreement are 14.88 +/- 3 on a maximum score of 88. The dispersion is enough for a good differentiation of the patients. (11 to 88, avec mean 62.93, SD 22.45) with a significant difference p < 0.002 between the control group and the population with speech disorders.

CONCLUSION

This test constructed on the concept of a composite assessment is validated.

The "Deglutition Handicap Index" a self-administrated dysphagia-specific quality of life questionnaire: temporal reliability

OBJECTIVE

The aim of this study is to contribute to the psychometric validation of the self-administrated dysphagia-specific quality of life questionnaire, the Deglutition Handicap Index. Created on the model of the "Voice Handicap Index". this questionnaire consists of 30 statements on deglutition related aspects in daily life (5 point-rating scale). It is subdivided in three domains of 10 items: physical (symptoms), functional (nutritional and respiratory consequences) and emotional (psychosocial consequences).

MATERIAL AND METHOD

57 patients were included suffering of any kind of swallowing disorders. 17 questionnaires were eliminated because 1 to 3 items were not anchored. A test retest performed in an interval of 2 weeks, allowed the measure of the intraclasse correlation coefficient and the limits of agreement with Bland and Altman graphics.

RESULTS

The intraclasse correlation coefficient was respectively 0.77 (0.64-0.90), 0.87 (0.79-0.94), 0.90 (0.84-0.96), 0.91 (0.85-0.96) for the Physical, Functional, Emotional and Total Scores. The limits of agreement are 9 points for the subscales and 20 points for the total score.

CONCLUSION

The DHI has been validated in term of content, concurrent and construct validity. The reliability was satisfied in term of internal consistency. It is now validated for the temporal reliability. The DHI is the solely specific quality of life questionnaire related to deglutition available for all kind of oropharyngeal swallowing disorders in adults available in clinical practice.

[Physico-chemical stability and sterility of non-opioid analgesics in solution]

OBJECTIVES

The combination of non-opioid analgesic drugs (P: paracetamol, K: ketoprofen and N: nefopam) is currently recommended for postoperative pain control. In practice, these analgesics are often administered in the same solution. We investigated the chemical stability and sterility of three mixtures of analgesics (P+K, P+N and K+N).

METHODS

For each mixture, concentrations of active principles were measured using high-performance liquid chromatography over 24 hours. These mixtures were cultured for microbiological colonization.

RESULTS

Our study demonstrated chemical and bacteriologic stability of these three mixtures over a 24-hour period. The results allow the use of P+K, P+N and K+N in the same ready to use solution.

Fossil ectomycorrhizae from the Middle Eocene

Fossil ectomycorrhizae were found recently among permineralized plant remains in the middle Eocene Princeton chert of British Columbia. The ectomycorrhizae are associated with roots of Pinus and have a Hartig net that extends to the endodermis, a pseudoparenchymatous mantle, and contiguous extramatrical hyphae that are simple-septate. The mycorrhizal rootlets lack root hairs and dichotomize repeatedly to form large, coralloid clusters. Reproductive structures are absent. Based on the morphological characteristics, and the identity of the host, the closely related basidiomycete genera Rhizopogon and Suillus are suggested as comparable extant mycorrhizal fungi. These exquisitely preserved specimens represent the first unequivocal occurrence of fossil ectomycorrhizae and demonstrate that such associations were well-established at least 50 million years ago.

Effects on sound localization of configuration and type of hearing impairment

Localization ability of 87 bilaterally hearing-impaired listeners was tested in the horizontal and vertical planes, frontally and laterally. In those with sensorineural hearing loss, it was found that deficits in localization accuracy in different regions of auditory space could be related to different configurations of hearing loss. For example, there were associations between vertical plane discrimination and high-frequency sensitivity; and front-rear discrimination and mid-to-high-frequency sensitivity. These results agree with theoretical expectations, while the outcome overall contrasts with previous reports that localization performance is unrelated to audiometric configuration. A comparison of 13 listeners with conductive/mixed types of impairment with a sensorineural-loss group, matched for degree of loss, showed that a conductive component adds significantly to localization disturbance, particularly in the horizontal plane. The probable reason is a disturbance of low-frequency interaural time cues, and this occurs because a higher proportion of low-frequency sound is likely to be transmitted via bone conduction relative to air conduction. Correlations between hearing loss and localization are only moderate, suggesting that aspects of hearing impairment, in addition to simple attenuation, may also reduce auditory localization performance.