The Relationship between Oxygenator Exhaust Pco2 and Arterial Pco2 During Hypothermic Cardiopulmonary Bypass

During cardiopulmonary bypass the partial pressure of carbon dioxide in oxygenator arterial blood (Paco2) can be estimated from the partial pressure of gas exhausting from the oxygenator (PEco2). Our hypothesis is that PEco2 may be used to estimate Paco2 with limits of agreement within 7 mmHg above and below the bias. (This is the reported relationship between arterial and end-tidal carbon dioxide during positive pressure ventilation in supine patients.)

During hypothermic (28-32°C) cardiopulmonary bypass using a Terumo Capiox SX membrane oxygenator, 80 oxygenator arterial blood samples were collected from 32 patients during cooling, stable hypothermia, and rewarming as per our usual clinical care. The Paco2 of oxygenator arterial blood at actual patient blood temperature was estimated by temperature correction of the oxygenator arterial blood sample measured in the laboratory at 37°C. PEco2 was measured by connecting a capnograph end-to-side to the oxygenator exhaust outlet. We used an alpha-stat approach to cardiopulmonary bypass management.

The mean difference between PEco2 and Paco2 was 0.6 mmHg, with limits of agreement (±2 SD) between -5 to +6 mmHg. PEco2 tended to underestimate Paco2 at low arterial temperatures, and overestimate at high arterial temperatures.

We have demonstrated that PEco2 can be used to estimate Paco2 during hypothermic cardiopulmonary bypass using a Terumo Capiox SX oxygenator with a degree of accuracy similar to that associated with the use of end-tidal carbon dioxide measurement during positive pressure ventilation in anaesthetized, supine patients.

Severe Uncontrolled Pain in Buttock in a Patient on Naltrexone: A Diagnostic Challenge

A 26-year-old woman with a history of intravenous drug use was admitted to hospital with worsening pain in the right buttock radiating to the lateral part of the thigh and to the calf with no suspicion of cauda equina compression. Eventually, a diagnosis of sacroiliitis was made and appropriate antibiotics were administered. Provision of analgesia for this patient was difficult. On admission her medications included naltrexone, venlafaxine and tramadol. Initially naltrexone was continued and analgesia provided by epidural local anaesthetic and clonidine, intravenous ketamine and oral agents. After several days, naltrexone was ceased and opioids were used in addition to the other analgesics. The epidural analgesia was only partially effective, perhaps because of inadequate blockade of the L4-S1 nerve roots, which carry sensation from the sacroiliac joint.

Naltrexone is a long-acting opioid antagonist. If opioid analgesia is planned, it is necessary to cease naltrexone for 24 to 72 hours. In an emergency, if non-opioid techniques prove ineffective, short-acting opioids can be titrated to effect in a monitored environment.

Adequate Images in Intraoperative Transoesophageal Echocardiography: A Quality Improvement Project

A suggested standard examination (SSE) for intraoperative transoesophageal echocardiography for cardiac surgery was developed at the Green Lane Department of Cardiothoracic and Otorhinolaryngology Anaesthesia at the Auckland City Hospital. The examination includes views to be recorded in all patients pre- and post-cardiopulmonary bypass. There are also additional views to be recorded in patients with valvular pathology. Using the SQUIRE (Standards for Quality Improvement Reporting Excellence) guidelines, we report an audit comparing acquisition ratios before and after introduction of the SSE. A baseline mean acquisition ratio of 0.62 was achieved, which was not significantly changed by the introduction of the SSE. Nevertheless, we found the SSE to be a useful audit tool and believe it might be of interest to others to assist with perioperative transoesophageal echocardiography quality assurance and education.

Phenotype-genotype correlations in patients with Marinesco-Sjögren syndrome

Marinesco-Sjögren syndrome (MSS; MIM 248800) is an autosomal recessive disorder characterized by congenital cerebellar ataxia, early cataracts, developmental delay, myopathy and short stature. Alterations in the gene SIL1 cause MSS in some patients with typical findings. In this study, molecular investigations including sequencing of the SIL1 gene, western blotting and microscopic investigations in fibroblast cultures were carried out in a cohort of 15 patients from 14 unrelated families, including the large, inbred family reported by Superneau et al., having the clinical features of MSS to provide insights into the pathophysiology of the disorder. A total of seven different mutations were found in eight of the patients from seven families. The mutations caused loss of the BIP-associated protein (BAP) protein in four patients by western blot. Novel clinical features such as dental abnormalities, iris coloboma, eczema and hormonal abnormalities were noticed in some patients, but there was no clear way to distinguish those with and without SIL1 mutations. Cultured fibroblasts contained numerous cytoplasmic inclusion bodies, similar to those identified in the brain of the whoozy mouse in five unrelated patients, three with and two without SIL1 mutations, suggesting some SIL1 negative patients share a common cellular pathogenesis with those who are SIL1 positive.

Penile biometry on prenatal magnetic resonance imaging

OBJECTIVE

In view of the implementation of magnetic resonance imaging (MRI) as an adjunct to ultrasonography in prenatal diagnosis, this study sought to demonstrate normal penile growth on prenatal MRI.

METHODS

This was a retrospective study of MRI of 194 male fetuses (18-34 weeks' gestation) with normal anatomy or minor abnormalities. On sagittal T2-weighted MRI sequences, we measured penile length from the glans tip to the scrotal edge (outer length) and from the glans tip to the symphyseal border (total length). Descriptive statistics, as well as correlation and regression analysis, were used to evaluate penile length in relation to gestation. T-tests were calculated to compare mean outer/total length on MRI with published ultrasound data.

RESULTS

Mean length values, including 95% CIs and percentiles, were defined. Penile length as a function of gestational age was expressed by the following regression equations: outer mean length = - 5.514 + 0.622 × gestational age in weeks; total mean length = - 8.865 + 1.312× gestational age in weeks. The correlation coefficients, r = 0.532 and r = 0.751, respectively, were statistically significant (P < 0.001). Comparison of outer penile length on MRI with published ultrasound penile length data showed no significant differences, while total penile length on MRI was significantly greater than ultrasound penile length (P < 0.001).

CONCLUSION

Our MRI results provide a reference range of fetal penile length, which, in addition to ultrasonography, may be helpful in the identification of genital anomalies. Outer penile length on MRI is equivalent to penile length measured on ultrasound, whereas total length is significantly greater.

Male sexual development in utero: testicular descent on prenatal magnetic resonance imaging

OBJECTIVE

To visualize in utero male fetal testicular descent on magnetic resonance imaging (MRI) and to correlate it with gestational age.

METHODS

This retrospective study included 202 MRI examination results of 199 male fetuses (17-39 gestational weeks) with normal anatomy or minor congenital abnormalities, following suspicion of anomalies on prenatal ultrasound examination. Using a 1.5-Tesla unit, multiplanar T2-weighted sequences were applied using a standard protocol to image and identify the scrotal content. The relative frequencies of unilateral and bilateral testicular descent were calculated and correlated with gestational age.

RESULTS

Between 17 and 25 gestational weeks, neither unilateral nor bilateral testicular descent was visualized on MRI. Testicular descent was first observed at 25 + 4 weeks, in 7.7% of cases. 12.5% of 27-week fetuses showed unilateral descent and 50% showed bilateral descent. Bilateral descent was observed in 95.7% of cases, on average, from 30 to 39 weeks.

CONCLUSIONS

Our results chart the time course of testicular descent on prenatal MRI, which may be helpful in the identification of normal male sexual development and in the diagnosis of congenital abnormalities, including the early detection of cryptorchidism.

Female external genitalia on fetal magnetic resonance imaging

OBJECTIVES

To characterize the normal development of the female external genitalia on fetal magnetic resonance imaging (MRI).

METHODS

This retrospective study included MRI examinations of 191 female fetuses (20-36 gestational weeks) with normal anatomy or minor abnormalities, following suspicion of anomalies on prenatal ultrasound examination. Using a 1.5-Tesla unit, the bilabial diameter was measured on T2-weighted sequences. Statistical description, as well as correlation and regression analyses, was used to evaluate bilabial diameter in relation to gestational age. MRI measurements were compared with published ultrasound data. The morphological appearance and signal intensities of the external genitalia were also assessed.

RESULTS

Mean bilabial diameters, with 95% CIs and percentiles, were defined. The bilabial diameter as a function of gestational age was expressed by the regression equation: bilabial diameter = - 11.336 + 0.836 × (gestational age in weeks). The correlation coefficient, r = 0.782, was statistically significant (P < 0.001). Bilabial diameter on MRI was not significantly different from that on ultrasound (P < 0.001). In addition, on MRI we observed changes in morphology of the external genitalia and in signal intensities with increasing gestational age.

CONCLUSIONS

We have provided a reference range of fetal bilabial diameter on MRI, which, in addition to ultrasound findings, may be helpful in the identification of genital anomalies.

Abnormalities of the upper extremities on fetal magnetic resonance imaging

OBJECTIVE

In view of the increasing use of fetal magnetic resonance imaging (MRI) as an adjunct to prenatal ultrasonography, we sought to demonstrate the visualization of upper extremity abnormalities and associated defects on MRI, with regard to fetal outcomes and compared with ultrasound imaging.

METHODS

This retrospective study included 29 fetuses with upper extremity abnormalities visualized with fetal MRI following suspicious ultrasound findings and confirmed by postnatal assessment or autopsy. On a 1.5-Tesla unit, dedicated sequences were applied to image the extremities. Central nervous system (CNS) and extra-CNS anomalies were assessed to define extremity abnormalities as isolated or as complex, with associated defects. Fetal outcome was identified from medical records. MRI and ultrasound findings, when available, were compared.

RESULTS

Isolated upper extremity abnormalities were found in three (10.3%) fetuses. In 26 (89.7%) fetuses complex abnormalities, including postural extremity disorders (21/26) and structural extremity abnormalities (15/26), were demonstrated. Associated defects involved: face (15/26); musculoskeletal system (14/26); thorax and cardio/pulmonary system (12/26); lower extremities (12/26); brain and skull (10/26); and abdomen (8/26). Of the 29 cases, 18 (62.1%) pregnancies were delivered and 11 (37.9%) were terminated. MRI and US findings were compared in 27/29 cases: the diagnosis was concordant in 14 (51.9%) of these cases, and additional findings were made on MRI in 13/27 (48.1%) cases.

CONCLUSIONS

Visualization of upper extremity abnormalities on fetal MRI enables differentiation between isolated defects and complex ones, which may be related to poor fetal prognosis. MRI generally confirms the ultrasound diagnosis, and may provide additional findings in certain cases.

Ehlers-Danlos arthrochalasia type (VIIA-B)--expanding the phenotype: from prenatal life through adulthood

The Ehlers-Danlos syndromes (EDS) form a clinically and genetically heterogeneous group of inherited connective-tissue disorders characterized by joint hypermobility, tissue fragility and skin abnormalities. Six subtypes have been well characterized based on clinical features and molecular genetic abnormalities. The arthrochalasia type EDS (formerly types VIIA and B) is characterized by severe generalized joint hypermobility with multiple dislocations including congenital bilateral dislocation of the hips, muscular hypotonia and distinct dysmorphic features. The diagnosis of the arthrochalasia type EDS is of importance in the neonatal period because of consequences of physical disability in later life. However, the differential diagnosis may be difficult because of overlap with other hypermobility syndromes. In addition, the significant hypotonia may direct the physician toward various neuromuscular diagnoses. As patients become older, the hypotonia decreases and facial features become less distinct. In this report, we describe seven patients at different ages. Timing of diagnosis varied from prenatal life to adult age. The diagnosis of EDS type VII was confirmed by biochemical studies or mutation analysis showing characteristic mutations in COL1A1 and COL1A2. These mutations result in skipping of exon 6, which leads to defective collagen synthesis. For physicians treating patients with EDS type VII, achieving mobility for the patient is the greatest challenge and it may be impossible because of recurrent dislocations of nearly all joints in severe cases.

Pneumocephalus--an unreported risk of Valsalva's manoeuvre following cochlear implantation

We describe a case of pneumocephalus as an unusual early postoperative complication following cochlear implantation. The aetiology of this condition we attribute to the patient's habit of 'ear popping' using Valsalva's manoeuvre.

Tinnitus in children with hearing loss

The results are reported of a survey of tinnitus in deaf children in secondary-school age. Of 158 children in five units for the partially hearing and two schools for the deaf. 78 were found to have tinnitus. The tinnitus was constant in two children and intermittent in the remaining 76. The frequency with which the tinnitus occurred, and its duration and loudness, are reported. Some children claimed that tinnitus reduced their hearing ability and speech discrimination. It some, tinnitus was associated with headache or vertigo. When it was unilateral, tinnitus was more commonly on the side of the better-hearing ear. A group of children was defined in whom the tinnitus had features that made it a particularly troublesome symptom.

Isolation of mitochondria from tissues and cells by differential centrifugation

Differential centrifugation is used to prepare a "heavy" mitochondrial fraction from liver. These mitochondria are relatively pure, highly coupled, and suitable for respiratory studies. This unit presents protocols for isolation of beef heart mitochondria (also suitable for respiratory studies), skeletal muscle mitochondria, and mitochondria from cultured cells can also be isolated from homogenates by differential centrifugation. Differential centrifugation, which separates cellular organelles based on sedimentation velocity, is a rapid method for preparing mitochondria for metabolic studies.

Purification of a crude mitochondrial fraction by density-gradient centrifugation

Most mitochondria prepared by differential centrifugation are contaminated to some extent by lysosomes, peroxisomes, tubular Golgi membranes, and small amounts of endoplasmic reticulum. Density gradient centrifugation using a variety of density media--sucrose, Percoll, Nycodenz, Iodixanol--is described here and is used to prepare purer fractions of mitochondria. The resulting gradient can be analyzed for three marker enzymes: succinate dehydrogenase (mitochondria), b-galactosidase (lysosomes), and catalase (peroxisomes).

Isolation of peroxisomes from tissues and cells by differential and density gradient centrifugation

Peroxisome purification depends on a two-step procedure: differential centrifugation to prepare a light mitochondrial fraction and fractionation on a density-gradient medium preferably iodixanol or Nycodenz, to isolate the peroxisome enriched fraction. The iodixanol gradient may be a preformed continuous gradient or a self-generating gradient. Alternatively a continuous Nycodenz gradient or a simple Nycodenz barrier may be used for the second step. The unit contains protocols for peroxisome isolation from rat liver, tissue culture cells (HepG2 cells), and yeast spheroplasts. The extent of endoplasmic reticulum contamination of the prep can be assessed using an assay for the marker enzyme NADPH-cytochrome creductase.

Isolation of lysosomes from tissues and cells by differential and density gradient centrifugation

This unit covers the use of Percoll, Nycodenz, and iodixanol for purification of lysosomes from a light mitochondrial pellet or postnuclear supernatant. The first protocol describes isolation of lysosomes from rat liver using a Percoll gradient; it includes some comments on using brain and kidney tissue as source material. Alternatively, this protocol can be modified to enhance the separation of lysosomes by organelle density perturbation. Another alternative uses a discontinuous gradient of Nycodenz to purify lysosomes from a rat liver light mitochondrial pellet. A continuous iodixanol gradient, which can be used to purify other organelles in the light mitochondrial fraction, is yet another alternative for purifying lysosomes. Lysosomes can also be isolated from some of the more commonly used cultured cells. The unit also includes assays for common lysosome marker enzymes.

Dual-purpose canola—a new opportunity in mixed farming systems

The term dual-purpose canola describes the use of a canola crop for forage before seed production. It could potentially provide a profitable and flexible break-crop option for mixed farms, but there have been no studies to test the concept in Australia. We investigated the feasibility of using canola in this way in field experiments near Canberra, Australia, from 2004 to 2006, using European winter and mid–late maturing Australian spring canola varieties. Winter varieties sown from early March to mid-April produced 2.5–5.0 t/ha of biomass providing 0.3–3.5 t/ha of high-quality forage grazed by sheep in winter. The spring varieties produced similar amounts of vegetative biomass from April sowing but were unsuited to the earlier March sowing as they flowered in early winter and did not recover from grazing. The canola forage was readily eaten by sheep; alkane-based estimates of diet composition indicated that >85% of the organic matter intake consisted of canola. Canola forage was also highly digestible (86–88%) and Merino hoggets grew at 210 g/day from a dry matter intake of 1530 g DM/day. The canola generally recovered well when grazed in winter before bud elongation. Delays in flowering associated with heavy grazing ranged from 0 to 4 days when grazed before buds were visible, to 28 days if the crop had commenced flowering. Significant delays in flowering (>14 days) associated with winter grazing did not reduce seed yield or oil content when favourable spring conditions allowed compensatory growth. Yield loss was observed when winter and spring conditions were unfavourable for compensatory growth, or if grazing continued too late into spring (late September) irrespective of seasonal conditions. The yield loss was more than offset by the value of the grazed forage and the mean gross margin for dual-purpose canola over the four experiments was $240 to $500 higher than for grain-only canola depending on the value assumed for the forage. The study indicates there is considerable scope to capture value from grazing early-sown canola crops during winter without significant, uneconomic trade-offs with seed yield. Further investigations in other medium to high rainfall environments in southern Australia are warranted.

How we do it: patient participation in cochlear implant selection

. Involving patients and parents in the choice of their cochlear implant encourages an active role in the process and facilitates 'bonding' and 'ownership' of the device. . The most frequent reasons given by patients for selecting a device included cochlear implant comfort and appearance. . We describe the Implant Programme based at the Royal National Throat, Nose and Ear Hospital, London, and also examine patient satisfaction with the scheme.

Impact of subsoil water use on wheat yield

Water stored deep in the soil profile is generally considered valuable to crop yield because it becomes available during grain filling, but the value of subsoil water for grain yield has not been isolated and quantified in the field. We used rainout shelters with irrigation to control the water supply to wheat crops that had different amounts of subsoil water available to isolate and quantify the efficiency with which the subsoil water was converted to grain yield. Under moderate post-anthesis stress, 10.5 mm of additional subsoil water used in the 1.35–1.85 m layer after anthesis increased grain yield by 0.62 t/ha, representing an efficiency of 59 kg/ha.mm. The additional yield resulted from a period of higher assimilation 12–27 days after anthesis and was related to an increase in grain size rather than other yield components. Under more severe stress with earlier onset, extra water use below 1.25 m was accompanied by additional water use in upper soil layers and it was more difficult to isolate and quantify the benefit of deep water to grain yield. The additional water used from all layers from the time the stress was imposed was converted to grain at 30–40 kg/ha.mm, but this increased to 60 kg/ha.mm for water used after anthesis. The high efficiency for subsoil water use is 3 times that typically expected for total seasonal water use, and twice that previously estimated for total post-anthesis water use in a similar environment. The results demonstrate that relatively small amounts of subsoil water can be highly valuable to grain yield.

A prospective randomized controlled trial evaluating alcohol on loudness perception in cochlear implant users

AIM

The aim of this study was to determine the effects of alcohol on the psychophysical responses in patients with cochlear implants. This has not been previously studied. It was also hoped to provide information that could suggest possible sites of action of the known effects of alcohol on the auditory pathway.

DESIGN

A prospective randomized placebo-controlled trial, with full ethical approval.

PARTICIPANTS

Eight successful cochlear implant users were selected, of whom two had bilateral implants which were tested separately. In total 10 cochlear implants were tested.

INTERVENTION

Alcohol was given in the form of vodka (50% alcohol, 1 mL/kg body weight) with 500 mL of orange and cranberry juice. The placebo control was given in the form of 500 mL of orange and cranberry juice alone.

OUTCOME MEASUREMENT

The 'comfort level' (C level) was recorded before, and 1 h after alcohol or placebo ingestion for each patient's cochlear implant. Blood alcohol concentration was determined prior to alcohol or placebo consumption and then repeated after 45, 60, 90 and 180 min.

RESULTS

The mean blood alcohol concentration 1 h after ingestion was 50 mg/dL. In the 'alcohol' arm the mean electrical unit increase in the C level was 19.9 with a standard deviation of 2.2. In the control arm the mean change in C level was 0.10 with a standard deviation of 0.3.

CONCLUSIONS

In this first prospective randomized control study of the effect of alcohol on sound perception in cochlear implant users, alcohol significantly increased the upper end of the dynamic range (C levels) in comparison with placebo (P = <0.0001 using paired t-test analysis). This effect is likely to be the result of change in the auditory pathways proximal to the cochlea.

A comparison of the analgesic efficacy and side-effects of paravertebral vs epidural blockade for thoracotomy--a systematic review and meta-analysis of randomized trials

Epidural analgesia is considered by many to be the best method of pain relief after major surgery. It is used routinely in many thoracic surgery centres. Although effective, side-effects include hypotension, urinary retention, incomplete (or failed) block, and, in rare cases, paraplegia. Paravertebral block (PVB) is an alternative technique that may offer comparable analgesic effectiveness and a better side-effect profile. We undertook a systematic review and meta-analysis of all relevant randomized trials comparing PVB with epidural analgesia in thoracic surgery. Data were abstracted and verified by both authors. Studies were tested for heterogeneity, and meta-analyses were done with random effects or fixed effects models. Weighted mean difference (WMD) was used for numerical outcomes and odds ratio (OR) for dichotomous outcomes, both with 95% CI. We identified 10 trials that had enrolled 520 thoracic surgery patients. All of the trials were small (n<130) and none were blinded. There was no significant difference between PVB and epidural groups for pain scores at 4-8, 24 or 48 h, WMD 0.37 (95% CI: -0.5, 121), 0.05 (-0.6, 0.7), -0.04 (-0.4, 0.3), respectively. Pulmonary complications occurred less often with PVB, OR 0.36 (0.14, 0.92). Urinary retention, OR 0.23 (0.10, 0.51), nausea and vomiting, OR 0.47 (0.24, 0.53), and hypotension, OR 0.23 (0.11, 0.48), were less common with PVB. Rates of failed block were lower in the PVB group, OR 0.28 (0.2, 0.6). PVB and epidural analgesia provide comparable pain relief after thoracic surgery, but PVB has a better side-effect profile and is associated with a reduction in pulmonary complications. PVB can be recommended for major thoracic surgery.

The adult phenotype in Costello syndrome

We report clinical findings in 17 adults with Costello syndrome ranging in age from 16 to 40 years. Two patients in this series have had bladder carcinoma, the only malignancy reported to affect adults with Costello syndrome. Benign tumors included multiple ductal papillomata in two women, and a fourth ventricle mass in one man, thought to be a choroid plexus papilloma. Endocrine problems in this series were osteoporosis, central hypogonadism, and delayed puberty. Other health problems were symptomatic Chiari malformations in three patients. Four patients had adult-onset gastro-esophageal reflux, three of whom had Chiari malformations. Fourteen adults had mild to moderate intellectual disability with three individuals having severe intellectual disability; 15 individuals attained some reading and writing skills and 14 showed ongoing acquisition of new skills into adulthood. On the basis of this data, we recommend that neuro-imaging be considered in adults with Costello syndrome if they develop symptoms suggestive of a Chiari malformation. In the event of pubertal delay, endocrine investigations are indicated and hormone treatment may be required. Bone density assessments should be performed in adults with Costello syndrome, particularly in those with pubertal abnormalities. Screening for microscopic hematuria as a marker for bladder carcinoma may be indicated, although this requires further evaluation.

Incidence of meningitis and of death from all causes among users of cochlear implants in the United Kingdom

BACKGROUND

During 2002, there was an increase in reports of bacterial meningitis among people with cochlear implants in Europe and North America. One model of implant, which included a space-occupying 'positioner', was recalled. Implantation of a positioner was shown to be a risk factor for meningitis among children in the United States. The situation in the United Kingdom was not known.

METHODS

We ascertained the cohort of people who had received cochlear implants with intra-cochlear electrodes in UK hospitals prior to 1 October 2002 and were permanently resident in the United Kingdom. We compared the incidence of meningitis, and the causes and incidence of death from all causes, between the cohort and reference populations.

RESULTS

Of 1851 children (66 with positioners), none had contracted meningitis. Neither the incidence rate of meningitis, nor the cumulative mortality from all causes, differed significantly between implanted children and values expected for the general population. Of 1779 adults (139 with positioners), five had contracted meningitis with three fatalities. No case of meningitis involved a positioner and four of the cases, including the fatalities, possessed risk factors unrelated to implantation. Although the incidence rate of meningitis was significantly higher in implanted adults than the general population, cumulative mortality from all causes was never higher, and was significantly lower at some time points after implantation.

CONCLUSION

Specific evidence of the association between bacterial meningitis and implantation with a positioner that arose in the United States and mainland Europe during 2002 has not been found in the United Kingdom.

Diffusion tensor imaging for the assessment of upper motor neuron integrity in ALS

BACKGROUND

High angular resolution diffusion tensor imaging (HARD) is an MRI technique that exploits the mobility of water molecules to yield maps of structural order and directionality of white matter tracts with greater precision than six-direction diffusion tensor imaging (DTI) schemes.

OBJECTIVE

To assess whether HARD is more sensitive than conventional MRI or neurologic assessment in detecting the upper motor neuron (UMN) pathology of patients with ALS.

METHODS

Twenty-five patients with definite UMN clinical signs and 23 healthy volunteers underwent conventional MRI. HARD datasets were collected from a subset of these participants plus four patients with isolated lower motor neuron (LMN) signs. ALS symptom severity was assessed by a neurologist, the conventional MR images were reviewed by neuroradiologists, and the DTI maps were subject to quantitative region of interest analysis.

RESULTS

Motor cortex hypointensity on T2-weighted images and corona radiata hyperintensity on proton density-weighted images distinguished patients with UMN involvement from volunteers with 100% specificity, but only 20% sensitivity. Fractional anisotropy (FA) was reduced in the posterior limb of the internal capsule in patients with UMN involvement compared to volunteers. A FA threshold value with a sensitivity of 95% to detect patients with ALS (including those with isolated LMN signs) had a specificity of 71%.

CONCLUSIONS

High angular resolution diffusion tensor imaging may be more sensitive than conventional MRI or neurologic assessment to the upper motor neuron (UMN) pathology of ALS, but it lacks the specificity required of a diagnostic marker. Instead, it is potentially useful as a quantitative tool for monitoring the progression of UMN pathology.

Annual patterns in bacterioplankton community variability in a humic lake

Bacterioplankton community composition (BCC) was monitored in a shallow humic lake in northern Wisconsin, USA, over 3 years using automated ribosomal intergenic spacer analysis (ARISA). Comparison of ARISA profiles of bacterial communities over time indicated that BCC was highly variable on a seasonal and annual scale. Nonmetric multidimensional scaling (MDS) analysis indicated little similarity in BCC from year to year. Nevertheless, annual patterns in bacterioplankton community diversity were observed. Trends in bacterioplankton community diversity were correlated to annual patterns in community succession observed for phytoplankton and zooplankton populations, consistent with the notion that food web interactions affect bacterioplankton community structure in this humic lake. Bacterioplankton communities experience a dramatic drop in richness and abundance each year in early summer, concurrent with an increase in the abundance of both mixotrophic and heterotrophic flagellates. A second drop in richness, but not abundance, is observed each year in late summer, coinciding with an intense bloom of the nonphagotrophic dinoflagellate Peridinium limbatum. A relationship between bacterial community composition, size, and abundance and the population dynamics of Daphnia was also observed. The noted synchrony between these major population and species shifts suggests that linkages across trophic levels play a role in determining the annual time course of events for the microbial and metazoan components of the plankton.

The effects of arbuscular mycorrhizas on soil aggregation depend on the interaction between plant and fungal species

•  Arbuscular mycorrhizal fungi (AMF) and roots mediate soil stabilization, although the mechanisms and how their interactions affect soil stabilization are not known. We tested the effects of specific plant-fungus combinations on aggregate stabilization, and whether hyphal length and root biomass determine stabilization, predicting that fungi producing more hyphae, and plants with higher root biomasses, would better stabilize soils. •  The percentage of water-stable aggregates (%WSA_1-2 mm ), hyphal lengths, and root biomass were measured from a five AMF × nine plant factorial experiment. Arbuscular mycorrhizal fungi with greater extradical mycelium production were represented by the Gigasporaceae and plants of high root biomass by grasses. Other taxa represented lower hyphal lengths and root biomass. •  An interaction between symbionts with respect to %WSA_1-2 mm was observed. Root biomass and total hyphal lengths were not positively correlated with %WSA. Combinations of grasses with Gigasporaceae fungi had the lowest %WSA. •  Mechanisms underlying aggregation were not elucidated by measuring root biomass and total hyphal lengths alone, suggesting other physiological or architectural mechanisms may be responsible.

Seasonal dynamics of phytoplankton and planktonic protozoan communities in a northern temperate humic lake: diversity in a dinoflagellate dominated system

Species diversity and richness, and seasonal population dynamics of phytoplankton, planktonic protozoa, and bacterioplankton sampled from the epilimnion of Crystal Bog in 2000, were examined in order to test the hypothesis that these groups' diversity and abundance patterns might be linked. Crystal Bog, a humic lake in Vilas County, Wisconsin, is part of the North Temperate Lakes Long-Term Ecological Research Site. Phytoplankton and planktonic protozoa were identified and enumerated in a settling chamber with an inverted microscope. Bacterial cells were enumerated with the use of fluorescence 4', 6'-diamidino-2-phenylindole (DAPI)-staining procedures, and automated ribosomal intergenic spacer analysis (ARISA) was used to assess bacterioplankton diversity. Bacterial cell counts showed little seasonal variation and averaged 2.6 x 10(6) cells/mL over the ice-free season. Phytoplankton and planktonic protozoan numbers varied by up to two orders of magnitude and were most numerous in late spring and summer. Dinoflagellates largely dominated Crystal Bog throughout the ice-free period, specifically Peridiniopsis quadridens in the spring, Peridinium limbatum in summer, and Gymnodinium fuscum and P. quadridens in fall. Brief blooms of Cryptomonas, Dinobryon, and Synura occurred between periods of dinoflagellate domination. The dominant dinoflagellate, Peridinium limbatum, was calculated to have a growth rate of 0.065 day(-1) and a doubling time of 10.7 days. Heterotrophic nanoflagellates (HNFs) were a consistent component of the planktonic protozoa; seasonal patterns were determined for three genera of HNFs (Monosiga, Bicosoeca, and Desmarella moniliformis). Three genera of ciliates (Coleps, Strobilidium, and Strombidium) comprised the greater part of the planktonic protozoa in Crystal Bog. The number of species of planktonic protozoa was too low to calculate a diversity index. Shannon-Weaver diversity indices for phytoplankton and bacterioplankton in the epilimnion followed very similar seasonal patterns in this lake, supporting the hypothesis that in freshwaters, diversity patterns of these groups are linked.

A novel retractor for use in cochlear implantation

A new self-retaining scalp retractor is described, which elevates the scalp away from the skull to allow better access and vision in preparing the bony recess for a cochlear implant and protect the pericranium from surgical trauma. It is designed for use with the present generation of small vertical scalp incisions in cochlear implant surgery. In these incisions, the part of the skull drilled to create the implant bed is not directly under the wound; instead, it extends under a flap of scalp and pericranium for 5 cm or more. The retractor is simple to use, and the authors believe that it represents a new type of retractor, which may have other uses in the fields of orthopedic; ear, nose, and throat, cosmetic, and plastic surgery. Photographs demonstrate the instrument in use. A cochlear implant company has agreed to manufacture the instrument.

Fractionation of lipoprotein subclasses in self-generated gradients of iodixanol

Chapter 5 described the use of self-generated gradients of iodixanol for the fractionation of human plasma lipoproteins into the major classes: high-density, low-density, and very low density (HDL, LDL, and VLDL). During the metabolism of plasma HDL and LDL, the lipid and apoprotein composition of the lipoprotein particles changes in such a manner that a series of subclasses exists, each with a distinctive range of densities (1). Thus, in KBr gradients, the two major subclasses, HDL(2) and HDL(3), have densities of 1.063-1.125 g/mL and 1.125-1.21 g/mL, respectively (1). In some individuals a third subclass (HDL1) is recognized (1.055-1.063 g/mL). Electrophoretic (2) and immunological (3,4) techniques have identified additional subfractions. Likewise, subclasses of LDL have been identified and isolated using shallow KBr gradients (5,6). The major LDL subfractions are LDL(1), LDL(2), and LDL(3), which have densities of 1.025-1.034 g/mL, 1.034-1.044 g/mL, and 1.044-1.060 g/mL, respectively (6), and electrophoretic analysis has identified more subfractions (7). The subfractions of LDL are of particular interest, as the presence of small, dense LDL particles in the plasma appears to be associated with a predisposition to cardiovascular disease, and they are recognized as a major causative factor in atherosclerosis (8). Methods for monitoring the LDL subclass pattern in population studies and in dietary and drug intervention trials are thus of considerable interest. This chapter is concerned primarily with the subfractionation of LDL. Although HDL subfractionation systems using iodixanol self-generated gradients have not yet been validated by direct comparison with other methods (e.g., gradient gel electrophoresis or KBr gradient centrifugation), a protocol is included.

Effects of insulin lispro and chronic vitamin C therapy on postprandial lipaemia, oxidative stress and endothelial function in patients with type 2 diabetes mellitus

BACKGROUND

Insulin therapy may influence cardiovascular disease (CVD) and lipid metabolism in type 2 diabetes (T2D). Exaggerated postprandial lipaemia (PPL) is a feature of diabetic dyslipidaemia affecting CVD via enhanced oxidative stress (OS) and endothelial dysfunction. We assessed endothelial function and OS during PPL following insulin and vitamin C. Twenty (17 M) T2D patients were studied (mean Hba1c 8.4%) at baseline, following 6 weeks of insulin lispro (0.2 Iu kg-1) and vitamin C 1-g daily. Eight-h lipid and glucose profiles were measured following a fatty meal. Endothelial function (flow-mediated vasodilatation: FMD) and OS were measured at fasting, 4 h and 8 h.

MATERIALS AND METHODS

Glucose, body mass index, and total and LDL cholesterol remained unchanged. FMD improved. Placebo group: fasting, 1.1 +/- 1.2 to 4.2 +/- 1.1% (P < 0.001); 4-h, 0.3 +/- 1.2 to 3.1 +/- 0.9% (P < 0.01); 8-h, 0.7 +/- 1.1 to 3.76 +/- 1.1% (P < 0.001). Vitamin C group: fasting, 0.9 +/- 1.1 to 6.1 +/- 1.3% (P < 0.001); 4-h, 0.7 +/- 1.5 to 4.9 +/- 2.1% (P < 0.001); 8-h, 0.8 +/- 0.9 to 5.8 +/- 0.6% (P < 0.01). Post-prandial lipaemia was attenuated: TG area-under-curve (mmol L-1 8 h-1), 52.6 +/- 11 to 39.1 +/- 12.5 (placebo group), P < 0.02; and 56.9 +/- 8 to 40.1 +/- 10.3 (vitamin C group), P < 0.02. Oxidative stress was reduced, with greater changes in the vitamin C group.

CONCLUSION

Insulin may thus exert vascular benefits in T2D, by modifying fasting and postprandial lipid metabolism resulting in reduced OS and improved EF. Vitamin C therapy may augment the vascular benefits of insulin in T2D through additional effects on OS and EF.

Cochlear implantation in Jervell and Lange-Nielsen syndrome

A case of familial prolonged QT interval and congenital sensorineural hearing loss is described emphasising the diagnostic and management implications. Jervell and Lange-Nielsen syndrome is important because of its potential association with sudden death in children with congenital sensorineural deafness. It is known to be associated with mutations of the genes KCNQ1 (KVQTI) and KCNE1 (Isk). The underlying molecular abnormality leads to cardiac and cochlear dysfunction through a potassium channel defect. All children with congenital sensorineural hearing loss who have suffered unexplained syncopal attacks or convulsions should be screened for this syndrome. There is also a strong case for including a 12 lead ECG as part of the investigative work up of all children with congenital sensorineural deafness in whom a firm aetiology has not been established.

Klinefelter syndrome and its variants: an update and review for the primary pediatrician

Klinefelter syndrome is the most common chromosomal abnormality in humans. Recent prospective, unbiased studies have clarified many of the previous misconceptions associated with Klinefelter syndrome, thereby improving our recognition and management of this condition for affected individuals. The primary-care physician has an important role in caring for these individuals and their families by providing anticipatory guidance regarding issues relating to endocrinology, behavior, development, and preventive medical care. Furthermore, the primary-care giver can serve as a valuable source of support and advocacy for the family of a boy with Klinefelter syndrome. We review the current state of knowledge regarding Klinefelter syndrome and its variants, with an emphasis on medical and early developmental interventions.

Scanning for telomeric deletions and duplications and uniparental disomy using genetic markers in 120 children with malformations

We screened 120 children with sporadic multiple congenital anomalies and either growth or mental retardation for uniparental disomy (UPD) or subtelomeric deletions. The screening used short tandem repeat polymorphisms (STRP) from the subtelomeric regions of 41 chromosome arms. Uninformative marker results were reanalyzed by using the next available marker on that chromosome arm. In total, approximately 25,000 genotypes were generated and analyzed for this study. Subtelomeric deletions of 1 Mb in size were excluded for 27 of 40 chromosome arms. Among the 120 subjects none was found to have UPD, but five subjects (4%, 95% confidence interval 1-9%) were found to have a deletion or duplication of one or more chromosome arms. We conclude that UPD is not a frequent cause of undiagnosed multiple congenital anomaly syndrome. In addition, we determined that 9p and 7q harbor chromosome length variations in the normal population. We conclude that subtelomeric marker analysis is effective for the detection of subtelomeric duplications and deletions, although it is labor intensive. Given a detection rate that is similar to prior studies and the large workload imposed by STRPs, we conclude that STRPs are an effective, but impractical, approach to the determination of segmental aneusomy given current technology.

Syndromic ear anomalies and renal ultrasounds

OBJECTIVE

Although many pediatricians pursue renal ultrasonography when patients are noted to have external ear malformations, there is much confusion over which specific ear malformations do and do not require imaging. The objective of this study was to delineate characteristics of a child with external ear malformations that suggest a greater risk of renal anomalies. We highlight several multiple congenital anomaly (MCA) syndromes that should be considered in a patient who has both ear and renal anomalies.

METHODS

Charts of patients who had ear anomalies and were seen for clinical genetics evaluations between 1981 and 2000 at Cedars-Sinai Medical Center in Los Angeles and Dartmouth-Hitchcock Medical Center in New Hampshire were reviewed retrospectively. Only patients who underwent renal ultrasound were included in the chart review. The literature was reviewed for the epidemiology of renal anomalies in the general population and in MCA syndromes with external ear anomalies. We defined a child as having an external ear anomaly when he or she had any of the following: preauricular pits and tags; microtia; anotia; or cup, lop, and other forms of dysplastic ears. A child was defined as having a renal anomaly if an ultrasound revealed any of the following: unilateral or bilateral renal agenesis; hypoplasia; crossed ectopia; horseshoe, pelvic, cystic kidney; hydronephrosis; duplicated ureters; megaureter; or vesicoureteric reflux.

RESULTS

Because clinical genetics assessments were made by the same clinician at both sites (J.M.G.), data were combined. A total of 42 patients with ear anomalies received renal ultrasound; 12 (29%) of them displayed renal anomalies. Of the 12 patients with renal anomalies, 11 (92%) also received a diagnosis of MCA syndrome. Eleven of 33 patients (33%) with MCA syndromes had renal anomalies, whereas 1 of 9 patients (11%) with isolated ear anomalies had renal anomalies. Specific disorders seen were CHARGE association, Townes-Brocks syndrome, branchio-oto-renal syndrome, Nager syndrome, and diabetic embryopathy.

CONCLUSIONS

We conclude that ear malformations are associated with an increased frequency of clinically significant structural renal anomalies compared with the general population. This is due to the observation that auricular malformations often are associated with specific MCA syndromes that have high incidences of renal anomalies. These include CHARGE association, Townes-Brocks syndrome, branchio-oto-renal syndrome, Nager syndrome, Miller syndrome, and diabetic embryopathy. Patients with auricular anomalies should be assessed carefully for accompanying dysmorphic features, including facial asymmetry; colobomas of the lid, iris, and retina; choanal atresia; jaw hypoplasia; branchial cysts or sinuses; cardiac murmurs; distal limb anomalies; and imperforate or anteriorly placed anus. If any of these features are present, then a renal ultrasound is useful not only in discovering renal anomalies but also in the diagnosis and management of MCA syndromes themselves. A renal ultrasound should be performed in patients with isolated preauricular pits, cup ears, or any other ear anomaly accompanied by 1 or more of the following: other malformations or dysmorphic features, a family history of deafness, auricular and/or renal malformations, or a maternal history of gestational diabetes. In the absence of these findings, renal ultrasonography is not indicated.