105. MEIOTIC ACROBATS: MONOTREME SEX CHROMOSOME ORGANISATION DURING SPERMATOGENESIS

Monotremes feature an extraordinarily complex sex chromosome system which shares extensive homology with bird sex chromosomes but no homology to sex chromosomes of other mammals (1,2,3). At meiotic prophase I the ten sex chromosomes in platypus (nine in echidna) assemble in a sex chromosome chain. We previously identified the multiple sex chromosomes in platypus and echidna that form the meiotic chain in males (1,2,4). We showed that sex chromosomes assembly in the chain in a specific order (5) and that they segregate alternately (1). In secondary spermatocytes we observed clustering of X and Y chromosomes in sperm (6). Our current research investigates the formation of the synaptonemal complex, recombination and meiotic silencing of monotreme sex chromosomes. Meiotic sex chromosome inactivation (MSCI) has been observed in eutherian mammals, marsupials and birds but has so far not been investigated experimentally in monotremes. We found that during pachytene the X5Y5 end of the chain closely associates with the nucleolus and accumulates repressive chromatin marks (e.g. histone variant mH2A). In contrast to the differential accumulation of mH2A we observe extensive loading of the cohesin SMC3 on sex chromosomes in particular during the pachytene stage of meiotic prophase I. We have also used markers of active transcription and gene expression analysis to investigate gene activity in platypus meiotic cells. I will discuss how these findings contribute to our current understanding of the meiotic organisation of monotreme sex chromosomes and the evolution of MSCI in birds and mammals. (1) Grützner et al. (2004), Nature 432: 913–917.(2) Rens et al. (2007), Genome Biology 16;8(11): R243.(3) Veyrunes et al. (2008), Genome Research, 18(6): 995–1004.(4) Rens et al. (2004), Proceedings of the National Academy of Sciences USA. 101 (46): 16 257–16 261.(5) Daish et al. (2009), Reprod Fertil Dev. 21(8): 976–84.(6) Tsend-Ayush et al. (2009), Chromosoma 118(1): 53–69.

Anodically bonded submicron microfluidic chambers

We demonstrate the use of anodic bonding to fabricate cells with characteristic size as large as 7 x 10 mm(2), with height of approximately 640 nm, and without any internal support structure. The cells were fabricated from Hoya SD-2 glass and silicon wafers, each with 3 mm thickness to maintain dimensional stability under internal pressure. Bonding was carried out at 350 degrees C and 450 V with an electrode structure that excluded the electric field from the open region. We detail fabrication and characterization steps and also discuss the design of the fill line for access to the cavity.

Retropharyngeal pseudomeningocele

A 38-year-old male was found to have a retropharyngeal pseudomeningocele along with C1 - C2 dislocation. Absence of any possible history, misleading circumstantial evidence and rarity of the entity made it impossible to diagnose the condition preoperatively. Concurrent medical problems dominated and the patient died. As a result, outcome of the pseudomeningocele could not be evaluated.

Late presentation of a type III axis fracture with spondyloptosis

A 58-year-old man presented with an undiagnosed Effendi type III classification fracture and spondyloptosis of the axis with remarkably normal neurology. We discuss his surgery 4 years since the initial injury, and the presentation, features and management of fractures of the axis.

Single walled carbon nanotubes induce indirect cytotoxicity by medium depletion in A549 lung cells

The ability of two types of single walled carbon nanotubes (SWCNT), namely Arc Discharge (AD) and HiPco single walled carbon nanotubes, to induce an indirect cytotoxicity in A549 lung cells by means of medium depletion was investigated. The nanotubes were dispersed in a commercial cell culture medium and subsequently removed by centrifugation and filtration. Spectroscopic analysis confirmed the removal of the nanotubes and showed differing degrees of alteration of the composition of the medium upon the removal of the nanotubes. The ability to induce an indirect cytotoxic effect by altering the medium was evaluated using two endpoints, namely the Alamar Blue (AB) and the Clonogenic assay. Exposure of the A549 cells to the depleted medium which had previously contained carbonaceous nanoparticles, revealed significant cytotoxicity for both endpoints employed. The results presented demonstrate that single walled carbon nanotubes can induce an indirect cytotoxicity by alteration of cell culture medium (in which they have previously been dispersed) which potentially results in a false positive toxic effect being observed in cytotoxicity studies.

Smear cytology in the intra-operative assessment of periodontoid pseudotumour of the craniocervical junction

OBJECTIVE

Periodontoid pseudotumours are lesions of presumed degenerative aetiology which typically occur in elderly patients with cervical myelopathy. The clinical and radiological differential diagnosis includes neoplastic and inflammatory lesions, and the exclusion of such lesions may be of value in the intra-operative management of the patient. This audit aimed to examine the value of intra-operative smear cytology in the management of this condition.

METHODS

The intra-operative smear cytological features of four cases of periodontoid pseudotumour were reviewed.

RESULTS

In each case the intra-operative cytological interpretation was in keeping with a non-neoplastic and non-inflammatory process.

CONCLUSION

These results suggest that intra-operative smear cytology can provide information on the value in the intra-operative management of patients with this lesion.

Sudden arrhythmic death syndrome: a national survey of sudden unexplained cardiac death

OBJECTIVE

To describe the characteristics of sudden arrhythmic death syndrome (SADS) and compare its incidence with official national mortality statistics for unascertained deaths.

DESIGN AND SETTING

Sudden unexplained deaths were prospectively surveyed through 117 coroners' jurisdictions in England. Consecutive cases meeting the following criteria were included: white Caucasian, aged 4-64 years, no history of cardiac disease, last seen alive within 12 h of death, normal coroner's autopsy, cardiac pathologist's confirmation of a normal heart and negative toxicology.

MAIN OUTCOME MEASURES

The estimated mortality from SADS was calculated and the official mortality statistics for unascertained causes of deaths in 4-64-year-olds was identified for the same time period.

RESULTS

115 coroner's cases were reported and 56 (49%) SADS victims were identified: mean age 32 years, range 7-64 years and 35 (63%) male. 7 of 39 cases (18%) had a family history of other premature sudden deaths (<45). The estimated mortality from SADS was 0.16/100 000 per annum (95% CI 0.12 to 0.21), compared with an official mortality of 0.10/100 000 per annum for International Classification of Diseases 798.1 (sudden death, cause unknown-instantaneous death) or 1.34/100 000 per annum for unascertained causes of death.

CONCLUSIONS

Deaths from SADS occur predominantly in young males. When compared with official mortality, the incidence of SADS may be up to eight times higher than estimated: more than 500 potential SADS cases per annum in England. Families with SADS carry genetic cardiac disease, placing them at risk of further sudden deaths. SADS should therefore be a certifiable cause of death prompting specialised cardiological evaluation of families.

Dynamic degenerative lumbar spondylolisthesis: diagnosis with axial loaded magnetic resonance imaging

STUDY DESIGN

Retrospective review of case notes and imaging.

OBJECTIVE

To show the advantage of axial loaded magnetic resonance imaging (MRI) for identification of dynamic degenerative spondylolisthesis as a suspected cause of spinal claudication.

SUMMARY OF BACKGROUND DATA

Degenerative spondylolisthesis typically occurs at L4/L5 and is usually evident on plain radiography. However, dynamic degenerative spondylolisthesis may become evident on erect radiographs when not shown on supine radiographs or MRI.

METHODS

The case notes and imaging (radiography, conventional MRI, and axial loaded MRI) in 2 patients with symptoms of spinal claudication were reviewed.

RESULTS

A 44-year-old female presented with a 3-year history of intermittent low back pain and right leg numbness after a fall. A 52-year-old female presented with a 4-year history of low back pain, bilateral leg weakness, and right leg numbness. In both cases, conventional MRI studies showed mild-to-moderate degenerative disc disease only with no evidence of abnormal spinal alignment or nerve root compression. Axial loaded MRI clearly showed the development of a degenerative spondylolisthesis with central canal stenosis and facet ganglion formation in 1 case.

CONCLUSIONS

Axial loaded MRI identified occult dynamic degenerative spondylolisthesis, which correlated with the clinical picture but was not shown on initial conventional MRI or plain radiography.

Post-awakening cortisol secretion during basic military training

Salivary free cortisol concentrations in the first 30 min after awakening were assessed in 12 healthy army recruits at the beginning, middle and end of an 11-week intensive physical training course. To ensure strict adherence to protocol saliva collection was supervised and collected on each sampling day immediately on waking and again 15 and 30 min later. Self-rated psychological assessments of state levels of stress, arousal and fatigue were performed in the evening of each sampling day. A within-subjects repeated-measures analysis of participants who completed the course (12 of the original 20) showed a significant main effect of cortisol concentration across all three sampling points after awakening (F((2,22))=54.516, p<0.0001) and a significant main effect of weeks into the training course (F((3,33))=4.390, p=0.010). Further analysis of this effect of measurement-week revealed that at weeks 3 and 6 total cortisol secretion estimated by area under the curve was lower (F((3,33))=4.602, p=0.008) compared to the beginning and end of the course. Surprisingly self-reported stress, arousal and fatigue did not differ significantly across weeks, despite the large dropout rate (40%) and self-evident pressures of the course. We conclude that when controlling for many confounding variables, including participant adherence, post-awakening cortisol levels are sensitive to stressful challenge over a period of weeks.

Quality of life assessment using the Short Form-12 (SF-12) questionnaire in patients with cervical spondylotic myelopathy: comparison with SF-36

STUDY DESIGN

Clinical outcome study comparing the Short Form-36 (SF-36) and Short Form-12 (SF-12) assessment scales in patients with cervical spondylotic myelopathy (CSM).

OBJECTIVES

To compare the validity, reliability, and sensitivity to change of the SF-12 and SF-36 scales in CSM patients undergoing decompressive surgery.

SUMMARY OF BACKGROUND DATA

The SF-36 is a generic Health Related Quality of Life (HRQoL) questionnaire, consisting of 36 questions that can be reported as a Physical (PCS) and Mental Component Summary (MCS). Recently, an abbreviated version of SF-36, the SF-12, which uses only 12 questions drawn from the SF-36, has been described.

METHODS

In this prospective study, patients with CSM undergoing decompressive surgery, self-completed the SF-36 questionnaire before surgery and at 6 months after surgery. SF-12 item responses were abstracted from the responses given to the SF-36 questionnaire. The validity, reliability, and sensitivity to change of the PCS and MCS components of SF-12 and SF-36 scales were compared.

RESULTS

Overall, 105 patients underwent anterior (N = 58) or posterior (N = 47) decompressive surgery. After surgery, there were improvements in the PCS components of both the SF-36 (40 +/- 2 to 54 +/- 2) and SF-12 (34 +/- 2 to 48 +/- 3), as well as in the MCS component of the SF-36 (48 +/- 2 to 63 +/- 2) and SF-12 (43 +/- 2 to 59 +/- 2) (P < 0.001). The sensitivity to change and absolute sensitivity for both SF-12 and SF-36 were comparable, but the reliability of SF-36 was marginally greater. There were close and linear correlations between the SF-36 and SF-12 scores for both the PCS and MCS components, before and after surgery (R = 0.86 to 0.93; P < 0.0001).

CONCLUSIONS

Both the SF-12 and SF-36 scales are valid and sensitive to changes in physical and mental health status in CSM patients, undergoing decompressive surgery. Despite its abbreviated nature, the SF-12 appears to be an adequate substitute for SF-36, and its brevity should increase its attractiveness to both clinicians and patients.

Factors Determining Patient Choice of Device for GH Therapy

AIM

To assess the factors determining patient choice of GH device, and whether offering free patient choice improves compliance with GH therapy.

METHODS

A prospective cross-sectional study performed on patients offered free choice of GH device in a regional growth clinic. In a subgroup having home delivery, GH compliance was assessed using ampoule counts.

RESULTS

125 patients (74 (59%) male), median (range) 9.30 (1.0-18.3) years were commenced on GH from January 2001 to March 2004, and offered free choice of device. 68 (54%) chose a needled device, and 57 (46%) needle-free. There was no statistical difference in age, sex or diagnostic category between the two groups. Light blue devices were more likely to be chosen by males (p=0.056). Questionnaires giving reasons for choosing a device were available in 40, and a further 50 gave reasons for both choosing a specific device and not choosing others. Other than choice of needled/needle-free device, the factor most likely to determine choice was 'ease of use'. Only 6 (4.8%) subsequently changed device, and compliance remained high but unchanged at approximately 90%.

CONCLUSIONS

There are no specific features which determine what GH device a patient will choose. For those units offering free patient choice, a wide range of different devices should be made available.

Interfacial friction of thin 3He slabs in the Knudsen limit

A high precision torsional oscillator has been used to study 3He films of thickness from 100 to 350 nm, in the temperature range 5<T<200 mK. This thickness is much smaller than the viscous penetration depth, and also much smaller than the low temperature inelastic mean-free path of 3He quasiparticles. Such films are observed to decouple from the motion of the oscillator below 60 mK. We interpret the frequency shift and dissipation data in terms of an interfacial friction model.

Intermediate follow-up after treatment of degenerative disc disease with the Bryan Cervical Disc Prosthesis: single-level and bi-level

STUDY DESIGN

Prospective, concurrently enrolled, multicenter trials of the Bryan Cervical Disc Prosthesis (Medtronic Sofamor Danek, Memphis, TN) were conducted for the treatment of patients with single-level and two-level (bi-level) degenerative disc disease of the cervical spine.

OBJECTIVES

The studies were designed to determine whether new functional intervertebral cervical disc prosthesis can provide relief from objective neurologic symptoms and signs, improve the patient's ability to perform activities of daily living, decrease pain, and maintain stability and segmental motion.

SUMMARY OF BACKGROUND DATA

The concept of accelerated degeneration of adjacent disc levels as a consequence of increased stress caused by interbody fusion of the cervical spine has been widely postulated. Therefore, reconstruction of a failed intervertebral disc with functional disc prosthesis should offer the same benefits as fusion while simultaneously providing motion and thereby protecting the adjacent level discs from the abnormal stresses associated with fusion.

METHODS

Patients with symptomatic cervical radiculopathy and/or myelopathy underwent implantation with the Bryan prosthesis after a standard anterior cervical discectomy. At scheduled follow-up periods, the effectiveness of the device was characterized by evaluating each patient's pain, neurologic function, and radiographically measured range of motion at the implanted level.

RESULTS

Clinical success for both studies exceeded the study acceptance criteria of 85%. At 1-year follow-up, the flexion-extension range of motion per level: Discectomy and implantation of the device alleviates neurologic symptoms and signs similar to anterior cervical discectomy and fusion. Radiographic evidence supports maintenance of motion. The procedure is safe and the patients recover quickly. At least 5 years of follow-up will be needed to assess the long-term functionality of the prosthesis and protective influence on adjacent levels.

Higher dietary carbohydrate content during intensified running training results in better maintenance of performance and mood state

The aim of this study was to determine whether consumption of a diet containing 8.5 g carbohydrate (CHO) x kg(-1) x day(-1) (high CHO; HCHO) compared with 5.4 g CHO x kg(-1) x day(-1) (control; Con) during a period of intensified training (IT) would result in better maintenance of physical performance and mood state. In a randomized cross-over design, seven trained runners [maximal O(2) uptake (Vo(2 max)) 64.7 +/- 2.6 ml x kg(-1) x min(-1)] performed two 11-day trials consuming either the Con or the HCHO diet. The last week of both trials consisted of IT. Performance was measured with a preloaded 8-km all-out run on the treadmill and 16-km all-out runs outdoors. Substrate utilization was measured using indirect calorimetry and continuous [U-(13)C]glucose infusion during 30 min of running at 58 and 77% Vo(2 max). Time to complete 8 km was negatively affected by the IT: time significantly increased by 61 +/- 23 and 155 +/- 38 s in the HCHO and Con trials, respectively. The 16-km times were significantly increased (by 8.2 +/- 2.1%) during the Con trial only. The Daily Analysis of Life Demands of Athletes questionnaire showed significant deterioration in mood states in both trials, whereas deterioration in global mood scores, as assessed with the Profile of Mood States, was more pronounced in the Con trial. Scores for fatigue were significantly higher in the Con compared with the HCHO trial. CHO oxidation decreased significantly from 1.7 +/- 0.2 to 1.2 +/- 0.2 g/min over the course of the Con trial, which was completely accounted for by a decrease in muscle glycogen oxidation. These findings indicate that an increase in dietary CHO content from 5.4 to 8.5 g CHO x kg(-1)x day(-1) (41 vs. 65% total energy intake, respectively) allowed better maintenance of physical performance and mood state over the course of training, thereby reducing the symptoms of overreaching.

Cardiological assessment of first-degree relatives in sudden arrhythmic death syndrome

4.1% of sudden cardiac deaths in the 16-64 age-group are unexplained. In this group, cardiac pathological findings are normal and toxicological tests are negative; termed sudden arrhythmic death syndrome (SADS). We searched for evidence of inherited cardiac disease in cases of SADS. Of 147 first-degree relatives of 32 people who died of SADS, 109 (74%) underwent cardiological assessment. Seven (22%) of the 32 families were diagnosed with inherited cardiac disease: four with long QT syndrome; one with non-structural cardiac electrophysiological disease; one with myotonic dystrophy; and one with hypertrophic cardiomyopathy. Families of people who die of SADS should be offered assessment in centres with experience of inherited cardiac disease.

Evidence for a Mott-Hubbard transition in a two-dimensional 3He fluid monolayer

The heat capacity and magnetization of a fluid 3He monolayer adsorbed on graphite plated with a bilayer of HD have been measured in the temperature range 1-60 mK. Approaching the density at which the monolayer solidifies into a sqrt[7]xsqrt[7] commensurate solid, we observe an apparent divergence of the effective mass and magnetization corresponding to a T=0 Mott-Hubbard transition between a 2D Fermi liquid and a magnetically disordered solid. The observations are consistent with the Brinkman-Rice-Anderson-Vollhardt scenario for a metal-insulator transition. We observe a leading order T2 correction to the linear term in heat capacity.

Effect of eccentric exercise on patients with chronic exertional compartment syndrome

There are a number of similarities between chronic exertional compartment syndrome (CECS) and the effects of high force eccentric contractions in healthy controls. We hypothesised that CECS patients would be particularly susceptible to pain, fatigue and swelling after eccentric exercise. Ten CECS patients [aged 30.3 (8.0) years, mean (SD)], 7 males) and 14 healthy controls [aged 32.3 (9.0) years, 7 males] performed 40 maximal eccentric contractions of the anterior tibial muscles at an angular velocity of 90(o) s(-1). Maximal voluntary isometric contractions (MVC), force generated by electrical stimulation at 10 Hz and 50 Hz and muscle thickness (measured by real-time ultrasound scanning) were measured before exercise and for 10 min afterwards. Ratings of pain and tenderness were made before exercise, then 24 h and 48 h later. The two groups were comparable for initial isometric strength and muscle size. MVC force immediately after exercise fell to 90 (2.5)% [mean (SEM)] in patients and 86.5 (2.4)% in controls (P<0.0005 for both groups) and had not recovered after 10 min. Preferential loss of force at the low stimulation frequency occurred in both groups to a similar extent (20%, P<0.0005) and continued to decline over 10 min of recovery. There was no significant change in muscle thickness in either group. Only mild pain and tenderness were reported by the controls. The patients showed great individual variation but their mean pain scores were significantly higher during dorsiflexion and palpation (P<0.05) 24 h after exercise. After 48 h the patients reported more pain during dorsiflexion (P=0.005), plantarflexion (P<0.05) and palpation (P<0.05). These results suggest that some, but not all, CECS patients may be more susceptible to the pain associated with eccentric contractions that is thought to be the cause of damage and inflammation of connective tissue.

An evaluation of the usefulness of two terminology models for integrating nursing diagnosis concepts into SNOMED Clinical Terms

OBJECTIVES

We evaluated the usefulness of two models for integrating nursing diagnosis concepts into SNOMED Clinical Terms (CT).

METHODS

First, we dissected nursing diagnosis term phrases from two source terminologies (North American Nursing Diagnosis Association Taxonomy 1 (NANDA) and Omaha System) into the semantic categories of the European Committee for Standardization (CEN) categorical structure and ISO reference terminology model (RTM). Second, we critically analyzed the similarities between the semantic links in the CEN and ISO models and the semantic links used to formally define diagnostic concepts in SNOMED CT.

RESULTS

Our findings demonstrated that focus, bearer/subject of information, and judgment were present in 100% of the NANDA and Omaha term phrases. The Omaha term phrases contained no additional descriptors beyond those considered mandatory in the CEN and ISO models. The comparison among the semantic links showed that SNOMED CT currently contains all but one of the semantic links needed to model the two source terminologies for integration. In conclusion, our findings support the potential utility of the CEN and ISO models for integrating nursing diagnostic concepts into SNOMED CT.