Effects of Tcte1 knockout on energy chain transportation and spermatogenesis: implications for male infertility

STUDY QUESTION

Is the Tcte1 mutation causative for male infertility?

SUMMARY ANSWER

Our collected data underline the complex and devastating effect of the single-gene mutation on the testicular molecular network, leading to male reproductive failure.

WHAT IS KNOWN ALREADY

Recent data have revealed mutations in genes related to axonemal dynein arms as causative for morphology and motility abnormalities in spermatozoa of infertile males, including dysplasia of fibrous sheath (DFS) and multiple morphological abnormalities in the sperm flagella (MMAF). The nexin-dynein regulatory complex (N-DRC) coordinates the dynein arm activity and is built from the DRC1-DRC7 proteins. DRC5 (TCTE1), one of the N-DRC elements, has already been reported as a candidate for abnormal sperm flagella beating; however, only in a restricted manner with no clear explanation of respective observations.

STUDY DESIGN SIZE DURATION

Using the CRISPR/Cas9 genome editing technique, a mouse Tcte1 gene knockout line was created on the basis of the C57Bl/6J strain. The mouse reproductive potential, semen characteristics, testicular gene expression levels, sperm ATP, and testis apoptosis level measurements were then assessed, followed by visualization of N-DRC proteins in sperm, and protein modeling in silico. Also, a pilot genomic sequencing study of samples from human infertile males (n = 248) was applied for screening of TCTE1 variants.

PARTICIPANTS/MATERIALS SETTING METHODS

To check the reproductive potential of KO mice, adult animals were crossed for delivery of three litters per caged pair, but for no longer than for 6 months, in various combinations of zygosity. All experiments were performed for wild-type (WT, control group), heterozygous Tcte1+/- and homozygous Tcte1-/- male mice. Gross anatomy was performed on testis and epididymis samples, followed by semen analysis. Sequencing of RNA (RNAseq; Illumina) was done for mice testis tissues. STRING interactions were checked for protein-protein interactions, based on changed expression levels of corresponding genes identified in the mouse testis RNAseq experiments. Immunofluorescence in situ staining was performed to detect the N-DRC complex proteins: Tcte1 (Drc5), Drc7, Fbxl13 (Drc6), and Eps8l1 (Drc3) in mouse spermatozoa. To determine the amount of ATP in spermatozoa, the luminescence level was measured. In addition, immunofluorescence in situ staining was performed to check the level of apoptosis via caspase 3 visualization on mouse testis samples. DNA from whole blood samples of infertile males (n = 137 with non-obstructive azoospermia or cryptozoospermia, n = 111 samples with a spectrum of oligoasthenoteratozoospermia, including n = 47 with asthenozoospermia) was extracted to perform genomic sequencing (WGS, WES, or Sanger). Protein prediction modeling of human-identified variants and the exon 3 structure deleted in the mouse knockout was also performed.

MAIN RESULTS AND THE ROLE OF CHANCE

No progeny at all was found for the homozygous males which were revealed to have oligoasthenoteratozoospermia, while heterozygous animals were fertile but manifested oligozoospermia, suggesting haploinsufficiency. RNA-sequencing of the testicular tissue showed the influence of Tcte1 mutations on the expression pattern of 21 genes responsible for mitochondrial ATP processing or linked with apoptosis or spermatogenesis. In Tcte1-/- males, the protein was revealed in only residual amounts in the sperm head nucleus and was not transported to the sperm flagella, as were other N-DRC components. Decreased ATP levels (2.4-fold lower) were found in the spermatozoa of homozygous mice, together with disturbed tail:midpiece ratios, leading to abnormal sperm tail beating. Casp3-positive signals (indicating apoptosis) were observed in spermatogonia only, at a similar level in all three mouse genotypes. Mutation screening of human infertile males revealed one novel and five ultra-rare heterogeneous variants (predicted as disease-causing) in 6.05% of the patients studied. Protein prediction modeling of identified variants revealed changes in the protein surface charge potential, leading to disruption in helix flexibility or its dynamics, thus suggesting disrupted interactions of TCTE1 with its binding partners located within the axoneme.

LARGE SCALE DATA

All data generated or analyzed during this study are included in this published article and its supplementary information files. RNAseq data are available in the GEO database (https://www.ncbi.nlm.nih.gov/geo/) under the accession number GSE207805. The results described in the publication are based on whole-genome or exome sequencing data which includes sensitive information in the form of patient-specific germline variants. Information regarding such variants must not be shared publicly following European Union legislation, therefore access to raw data that support the findings of this study are available from the corresponding author upon reasonable request.

LIMITATIONS REASONS FOR CAUTION

In the study, the in vitro fertilization performance of sperm from homozygous male mice was not checked.

WIDER IMPLICATIONS OF THE FINDINGS

This study contains novel and comprehensive data concerning the role of TCTE1 in male infertility. The TCTE1 gene is the next one that should be added to the 'male infertility list' because of its crucial role in spermatogenesis and proper sperm functioning.

STUDY FUNDING/COMPETING INTERESTS

This work was supported by National Science Centre in Poland, grants no.: 2015/17/B/NZ2/01157 and 2020/37/B/NZ5/00549 (to M.K.), 2017/26/D/NZ5/00789 (to A.M.), and HD096723, GM127569-03, NIH SAP #4100085736 PA DoH (to A.N.Y.). The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported.

Deletion of Sod1 in Motor Neurons Exacerbates Age-Related Changes in Axons and Neuromuscular Junctions in Mice

Whole-body knock-out of Cu,Zn superoxide dismutase (Sod1KO) results in accelerated, age-related loss of muscle mass and function associated with neuromuscular junction (NMJ) breakdown similar to sarcopenia. In order to determine whether altered redox in motor neurons underlies this phenotype, an inducible neuron-specific deletion of Sod1 (i-mnSod1KO) was compared with wild-type (WT) mice of different ages (adult, mid-age, and old) and whole-body Sod1KO mice. Nerve oxidative damage, motor neuron numbers and structural changes to neurons and NMJ were examined. Tamoxifen-induced deletion of neuronal Sod1 from two months of age. No specific effect of a lack of neuronal Sod1 was seen on markers of nerve oxidation (electron paramagnetic resonance of an in vivo spin probe, protein carbonyl, or protein 3-nitrotyrosine contents). i-mnSod1KO mice showed increased denervated NMJ, reduced numbers of large axons and increased number of small axons compared with old WT mice. A large proportion of the innervated NMJs in old i-mnSod1KO mice displayed a simpler structure than that seen in adult or old WT mice. Thus, previous work showed that neuronal deletion of Sod1 induced exaggerated loss of muscle in old mice, and we report that this deletion leads to a specific nerve phenotype including reduced axonal area, increased proportion of denervated NMJ, and reduced acetyl choline receptor complexity. Other changes in nerve and NMJ structure seen in the old i-mnSod1KO mice reflect aging of the mice.

Genomic testing for copy number and single nucleotide variants in spermatogenic failure

PURPOSE

To identify clinically significant genomic copy number (CNV) and single nucleotide variants (SNV) in males with unexplained spermatogenic failure (SPGF).

MATERIALS AND METHODS

Peripheral blood DNA from 97/102 study participants diagnosed with oligozoospermia, severe oligozoospermia, or non-obstructive azoospermia (NOA) was analyzed for CNVs via array comparative genomic hybridization (aCGH) and SNVs using whole-exome sequencing (WES).

RESULTS

Of the 2544 CNVs identified in individuals with SPGF, > 90% were small, ranging from 0.6 to 75 kb. Thirty, clinically relevant genomic aberrations, were detected in 28 patients (~ 29%). These included likely diagnostic CNVs in 3/41 NOA patients (~ 7%): 1 hemizygous, intragenic TEX11 deletion, 1 hemizygous DDX53 full gene deletion, and 1 homozygous, intragenic STK11 deletion. High-level mosaicism for X chromosome disomy (~ 10% 46,XY and ~ 90% 47,XXY) was also identified in 3 of 41 NOA patients who previously tested normal with conventional karyotyping. The remaining 24 CNVs detected were heterozygous, autosomal recessive carrier variants. Follow-up WES analysis confirmed 8 of 27 (30%) CNVs (X chromosome disomy excluded). WES analysis additionally identified 13 significant SNVs and/or indels in 9 patients (~ 9%) including X-linked AR, KAL1, and NR0B1 variants.

CONCLUSION

Using a combined genome-wide aCGH/WES approach, we identified pathogenic and likely pathogenic SNVs and CNVs in 15 patients (15%) with unexplained SPGF. This value equals the detection rate of conventional testing for aneuploidies and is considerably higher than the prevalence of Y chromosome microdeletions. Our results underscore the importance of comprehensive genomic analysis in emerging diagnostic testing of complex conditions like male infertility.

Abstract 788: Differences in somatic TP53 mutation type in breast tumors by race and receptor status

Somatic driver mutations in TP53 are associated with triple negative breast cancer (TNBC) and poorer outcomes. African American women with breast cancer are more likely to have TNBC and TP53 driver mutations. Missense driver mutations in TP53 can be loss-of function (LOF) or gain-of-function (GOF). Additionally, some variants show dominant negative (DNE) activity. There are a number of hot-spot TP53 mutations, many occurring at CpG sites. Given the differences in TNBC status and TP53 driver mutation frequency by race, we wanted to determine if there are differences in TP53 mutation type by race. From multiple databases and a literature review, we identified 98 studies with patient race and TP53 mutation details. We compiled TP53 mutations from 2964 breast tumors from these 98 studies. The cohort included 715 (24.1%) Asian, 258 (8.7%) African (AA), and 1931 (65.1%) European (EA) ancestry individuals. Additionally, 60 patients (2%) had Hispanic or Latina ethnicity. Of the somatic TP53 mutations, 939 (31.7%) were GOF, 1739 (58.7%) were LOF, while the remaining 286 (9.6%) were not able to be classified by existing literature. With respect to DNE activity, 1246 (42%) showed DNE, 1190 (40.1%) showed no DNE, and 528 (17.8%) were unknown DNE status. CpG hotspots accounted for 613 (20.6%) mutations. Using Fisher's Exact test, we did not identify significant associations between any of the functional categories and overall race. However, 35.8% of tumors from EA individuals had GOF mutations compared to 29% in AA individuals (p=0.04). Mutations with DNE activity were positively associated with TNBC (OR=1.37, p=0.03) and negative estrogen receptor (ER) status (OR=1.38; p=0.005). Patients with hotspot mutations were slightly younger (mean age 53.61) compared to those with non-hotspot mutations (mean age 55.04), and this association neared significance (p=0.065). Larger cohorts are needed, in particular the AA cohort, to further elucidate some of these borderline findings. In summary, ER negative and TNBC breast tumors are more likely to have DNE TP53 mutations which could reflect biological processes.

Citation Format: Nijole Pollock, Johnny Ramroop, Joseph McElroy, Amanda E. Toland. Differences in somatic TP53 mutation type in breast tumors by race and receptor status [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 788.

Familial Infertility (Azoospermia and Cryptozoospermia) in Two Brothers-Carriers of t(1;7) Complex Chromosomal Rearrangement (CCR): Molecular Cytogenetic Analysis

Structural aberrations involving more than two breakpoints on two or more chromosomes are known as complex chromosomal rearrangements (CCRs). They can reduce fertility through gametogenesis arrest developed due to disrupted chromosomal pairing in the pachytene stage. We present a familial case of two infertile brothers (with azoospermia and cryptozoospermia) and their mother, carriers of an exceptional type of CCR involving chromosomes 1 and 7 and three breakpoints. The aim was to identify whether meiotic disruption was caused by CCR and/or genomic mutations. Additionally, we performed a literature survey for male CCR carriers with reproductive failures. The characterization of the CCR chromosomes and potential genomic aberrations was performed using: G-banding using trypsin and Giemsa staining (GTG banding), fluorescent in situ hybridization (FISH) (including multicolor FISH (mFISH) and bacterial artificial chromosome (BAC)-FISH), and genome-wide array comparative genomic hybridization (aCGH). The CCR description was established as: der(1)(1qter->1q42.3::1p21->1q42.3::7p14.3->7pter), der(7)(1pter->1p2 1::7p14.3->7qter). aCGH revealed three rare genes variants: ASMT, GARNL3, and SESTD1, which were ruled out due to unlikely biological functions. The aCGH analysis of three breakpoint CCR regions did not reveal copy number variations (CNVs) with biologically plausible genes. Synaptonemal complex evaluation (brother-1; spermatocytes II/oligobiopsy; the silver staining technique) showed incomplete conjugation of the chromosomes. Associations between CCR and the sex chromosomes (by FISH) were not found. A meiotic segregation pattern (brother-2; ejaculated spermatozoa; FISH) revealed 29.21% genetically normal/balanced spermatozoa. The aCGH analysis could not detect smaller intergenic CNVs of few kb or smaller (indels of single exons or few nucleotides). Since chromosomal aberrations frequently do not affect the phenotype of the carrier, in contrast to the negative influence on spermatogenesis, there is an obvious need for genomic sequencing to investigate the point mutations that may be responsible for the differences between the azoospermic and cryptozoospermic phenotypes observed in a family. Progeny from the same parents provide a unique opportunity to discover a novel genomic background of male infertility.

HyPer2 imaging reveals temporal and heterogeneous hydrogen peroxide changes in denervated and aged skeletal muscle fibers in vivo

To determine the role of denervation and motor unit turnover in the age-related increase in skeletal muscle oxidative stress, the hydrogen peroxide (H₂O₂) specific, genetically-encoded, fluorescent cyto-HyPer2 probe was expressed in mouse anterior tibialis (AT) muscle and compared with ex vivo measurements of mitochondrial oxidant generation. Crush of the peroneal nerve induced increased mitochondrial peroxide generation, measured in permeabilised AT fibers ex vivo and intra vital confocal microscopy of cyto-HyPer2 fluorescence showed increased cytosolic H₂O₂ in a sub-set (~24%) of individual fibers associated with onset of fiber atrophy. In comparison, mitochondrial peroxide generation was also increased in resting muscle from old (26 month) mice compared with adult (6-8 month) mice, but no age effect on fiber cytosolic H₂O₂ in vivo was seen. Thus ageing is associated with an increased ability of muscle fibers to maintain cytosolic redox homeostasis in the presence of denervation-induced increase in mitochondrial peroxide generation.

Malignant Hyperthermia and Day Stay Surgery

Patients who are malignant hyperthermia susceptible are often admitted overnight for observation, even after minor surgery. They may be declined care in a stand-alone day stay unit. This prospective audit set out to investigate whether patients susceptible to malignant hyperthermia can be safely treated as day stay patients.

The audit was conducted for four years from late 2000. All patients who were known to be susceptible to malignant hyperthermia, and their untested relatives, who received day stay anaesthesia were included in the audit. Malignant hyperthermia status, age, duration of anaesthesia, anaesthetic technique, type of procedure, intraoperative and postanaesthesia care unit observations and complications were recorded. All patients received a trigger-free anaesthetic technique. Detailed postanaesthesia care unit monitoring was undertaken and patients were observed for two and a half hours postoperatively.

Seventy-two patients were included in the audit. General anaesthesia was administered to 85% and regional to 15%. Only minor complications arose in the postoperative period, and none suggested a malignant hyperthermia reaction. Postanaesthesia care unit nursing staff contacted 49 (68%) of the patients the following day, and there was no evidence of malignant hyperthermia reactions.

This audit suggests that malignant hyperthermia susceptible patients can be safely managed as day stay patients in appropriate facilities, with appropriate postoperative care.

Safe Duration of Postoperative Monitoring for Malignant Hyperthermia Susceptible Patients

Postoperative management of malignant hyperthermia (MH) susceptible patients has changed substantially over the last 20 years, with many patients now managed as day cases. Our previous policy was to monitor known MH susceptible patients (and relatives of known MH susceptible individuals not yet investigated by muscle biopsy) for four hours in the Post Anaesthetic Care Unit. However, anaesthetic literature reports suggest that MH reactions usually commence within one hour of anaesthesia. For this reason we conducted a retrospective review of Post Anaesthetic Care Unit data in 254 MH susceptible/related patients treated between 1991 and late 2000. On the basis of this review we instituted a policy change and reduced our monitoring time to one hour in the Post Anaesthetic Care Unit with a further 1.5h in a step-down unit if indicated. A prospective study in a further 68 MH susceptible/related patients showed that no MH reactions were missed due to the shorter monitoring period.

X-linked ADGRG2 mutation and obstructive azoospermia in a large Pakistani family

We performed whole exome sequencing to identify an unknown genetic cause of azoospermia and male infertility in a large Pakistani family. Three infertile males were subjected to semen analysis, hormone testing, testicular histology, ultrasonography, karyotyping, Y-chromosome microdeletion and CFTR testing. The clinical testing suggested a diagnosis of obstructive azoospermia (OA). To identify the cause, we performed whole exome sequencing (WES) for 2 infertile brothers and 2 fertile family members. For segregation analysis and variant confirmation, we performed Sanger sequencing. WES data analysis of the family revealed segregated variants in 3 candidate genes. We considered novel nonsense variant c.2440C > T(p.Arg814*) in X-linked gene ADGRG2 as biologically most plausible. It is predicted to truncate the protein by 204 amino acids (aa) at a key transmembrane domain. Adgrg2-knockout male mice show sperm loss due to obstructive fluid stasis, while ADGRG2 mutations cause OA in the infertile male patients. Our analysis of testicular histology reveals secondary severe reduction of spermatogenesis, consistent with human and knockout mouse phenotypes. The ADGRG2 nonsense mutation is absent in the largest population databases, ExAC and gnomAD. Analysis of the novel nonsense mutation in extended family members confirmed co-segregation of the mutation with OA in all affected males. The likely pathogenic nature of the mutation is supported by its truncation effect on the transmembrane domain and distinctive ultrasound results. The study demonstrates effectiveness of WES in discovering a genetic cause of azoospermia.

A scoping review to explore how universal design for learning is described and implemented by rehabilitation health professionals in school settings

BACKGROUND

Universal design for learning (UDL) is a framework that provides guidelines to support children with diverse needs in the classroom and promotes inclusion of all children. Although UDL is recognized as a promising approach for school-based rehabilitation health professionals (RHPs), there are no studies that synthesize evidence on the use of UDL by RHPs in the school setting. Therefore, the research question for this study is: How is UDL described and implemented in school settings by RHPs? This study specifically examined literature from occupational therapy, physiotherapy, and speech-language pathology.

METHODS

A scoping review was completed to (a) summarize how UDL is described in the rehabilitation literature, (b) summarize the recommended and reported role of RHPs in the delivery of UDL, and (c) identify gaps in the evidence base. CINAHL, Embase, MEDLINE, PsychINFO, Sociological Abstracts, Web of Science, and ERIC electronic databases were searched. Numerical summaries and theoretical thematic analysis were used to describe the data both quantitatively and qualitatively.

RESULTS

Inclusion criteria were achieved for 45 of the 3,998 screened documents. Most of the included documents lacked a definition of UDL. Analysis suggested that speech-language pathologists and occupational therapists implement UDL in a variety of ways within the school setting. No physiotherapy literature was found, and limited high-level empirical research has been conducted within rehabilitation.

CONCLUSION

This scoping review provides a broad understanding of how RHPs describe and implement UDL-aligned services in school settings. UDL is a promising framework that provides RHPs with guidance on how to support children with diverse needs in the classroom, with the overall aim to promote inclusion of all children. There is a need for further research to determine the effectiveness of UDL as implemented by RHPs and to examine the role of physiotherapists in using UDL-type services.

Familial deletion of the HOXA gene cluster associated with Hand-Foot-Genital syndrome and phenotypic variability

Hand-Foot-Genital syndrome is a rare autosomal dominant condition characterized by distal limb anomalies and urogenital malformations. This disorder is associated with loss-of-function mutations in the HOXA13 gene. HOXA13 plays an important role in the development of distal limbs and lower genitourinary tract of the fetus. We report a novel familial 589 kb deletion in the 7p15.2 region identified in a male toddler and his mother. The proband had severe penoscrotal hypospadias, mild skeletal anomalies of the hands and feet, cardiac, renal, and gastrointestinal anomalies. His mother had a bicornuate uterus, cervical incompetence, and minor anomalies of her hands and feet. This family was found to have the smallest reported deletion of 7p15.2 to date, and presented with features typical of Hand-Foot-Genital syndrome in the mother, but much more severe phenotype in her son. This deletion included the entire HOXA cluster in addition to the SKAP2 and EVX1 genes. An RT-PCR analysis was performed to determine the expression of the HOXA genes in the proband and to explore a parent-of-origin effect. Our expression studies did not support the hypothesis of an imprinted status of the HOXA2, HOXA3, HOXA5, and HOXA11 genes in peripheral blood. To our knowledge, this is the first familial 7p15.2 deletion. This family raises possibility for sexual dimorphism as a mechanism for phenotypic variability in patients with the HOXA gene cluster deletions. © 2016 Wiley Periodicals, Inc.

Implementing Client-Centred Practice: Why is it so Difficult to Do?

This paper explores the challenges of implementing client-centred occupational therapy practice. While many occupational therapists believe in the principles of client-centred practice and espouse them, it seems much more difficult to implement these into everyday practice. Findings from three qualitative studies with three different populations (i.e., family-centred care for children and their families, community-based home care, facility-based care for older adults) are used to illustrate the challenges which are divided into three broad categories: challenges at the level of the system, at the level of the therapist and at the level of the client. Suggestions for change at each level are addressed. Organizations, therapists and clients must work together to facilitate these changes and ensure that each occupational therapy client receives respectful, supportive, coordinated, flexible and individualized service.

The Clinical Utility of the Test of Playfulness

Occupational therapists' increased focus on play as an occupation has created a need for play assessments that reflect this perspective. This study examined the clinical utility of the recently developed Test of Playfulness (ToP) (Bundy, 1997a) when used with children with disabilities. Changes in the participant's views of the child, the therapy goals, and the intervention plans after using the ToP were explored. Fourteen paediatric occupational therapists assessed children using the ToP, completed a clinical utility questionnaire and attended a focus group. Participants found the ToP easy to administer and score, however some found interpreting the results difficult. The ToP highlights the interactions between the child, activity and environment, and illustrates the child's strengths in his/her role as a player. The results suggest the ToP is a useful tool for assessing playfulness. Additional education and research is needed to provide further direction for intervention and incorporation into practice.

Safe duration of postoperative monitoring for malignant hyperthermia patients administered non-triggering anaesthesia: an update

The postoperative care of malignant hyperthermia (MH) patients is subject to international variation, with a paucity of data in the literature to guide management. Over a series of three studies, our aim was to evaluate whether MH-susceptible patients (and relatives who had not yet been investigated), who had received a non-triggering anaesthetic, could be managed in the same way as the standard surgical population. Following a retrospective study, 206 anaesthetics were administered in a prospective second study to MH-susceptible/related individuals who were monitored for a minimum of one hour in the post anaesthesia care unit and a further 90 minutes in a step-down facility. No problems relating to MH were encountered. The postoperative monitoring time was subsequently changed and, in a third study, patients were managed no differently from standard surgical patients. One hundred and twenty-five anaesthetics were administered with no evidence of problems. This data shows that standard postoperative monitoring times are safe and appropriate in MH-susceptible patients.

Managing the health of the elite athlete: a new integrated performance health management and coaching model

Elite athletes endeavour to train and compete even when ill or injured. Their motivation may be intrinsic or due to coach and team pressures. The sports medicine physician plays an important role to risk-manage the health of the competing athlete in partnership with the coach and other members of the support team. The sports medicine physician needs to strike the right ethical and operational balance between health management and optimising performance. It is necessary to revisit the popular delivery model of sports medicine and science services to elite athletes based on the current reductionist multispecialist system lacking in practice an integrated approach and effective communication. Athlete and coach in isolation or with a member of the multidisciplinary support team, often not qualified or experienced to do so, decide on the utilisation of services and how to apply the recommendations. We propose a new Integrated Performance Health Management and Coaching model based on the UK Athletics experience in preparation for the London Olympic and Paralympic Games. The Medical and Coaching Teams are managed by qualified and experienced individuals operating in synergy towards a common performance goal, accountable to a Performance Director and ultimately to the Board of Directors. We describe the systems, processes and implementation strategies to assist the athlete, coach and support teams to continuously monitor and manage athlete health and performance. These systems facilitate a balanced approach to training and competing decisions, especially while the athlete is ill or injured. They take into account the best medical advice and athlete preference. This Integrated Performance Health Management and Coaching model underpinned the Track and Field Gold Medal performances at the London Olympic and Paralympic Games.

Sequence capture and massively parallel sequencing to detect mutations associated with malignant hyperthermia

BACKGROUND

Malignant hyperthermia (MH) is a potentially fatal pharmacogenetic disorder in which intracellular calcium homeostasis in the skeletal muscle of susceptible individuals is disrupted upon exposure to halogenated anaesthetics. While MH is linked to the ryanodine receptor (RYR1) on chromosome 19 and the α1S subunit of the voltage-dependent L-type calcium channel (CACNA1S) on chromosome 1, mutations have been found in only 50-70% of patients, and subsequently, there is a need for a more powerful screening tool.

METHODS

Genomic DNA capture and next-generation sequencing was used to screen 32 genes involved in excitation-contraction coupling, skeletal muscle calcium homeostasis, or immune response in two MH patients. Lymphoblastoid cell lines were used to functionally characterize candidate RYR1 mutations in one family.

RESULTS

Sequence analysis revealed two putative causative mutations in RYR1 in one patient. Segregation analysis and functional analysis support a causative role of the detected variants. The amount of Ca(2+) released after stimulation with 4-chloro-m-cresol from B lymphocytes of the MH-susceptible patients in the family was significantly greater compared with that of Ca(2+) released from cells of an MH-negative family member. In the other patient, no causative mutations were identified in the 32 genes screened.

CONCLUSIONS

In this study, we successfully demonstrate the use of genomic DNA capture and next-generation sequencing for identification of putative mutations causing MH. We also suggest that whole exome sequencing may be necessary to identify MH causing mutations in patients where no mutations in RYR1 and CACNA1S have been identified thus far.

Preparation of Datex-Ohmeda Aestiva® and Aisys® anaesthetic machines for use in malignant hyperthermia susceptible patients

Preparation of anaesthesia machines for use by malignant hyperthermia susceptible patients requires purging the machines of halogenated anaesthetic agents. The endpoint of this process is to reach a gas concentration of 5 ppm or less, which has been arbitrarily chosen as the safe limit of exposure to avoid triggering a malignant hyperthermia event. We examined the washout characteristics of sevoflurane and desflurane from the Datex-Ohmeda Aestiva® Anaesthesia System and Aisys® Anaesthesia Carestation®anaesthetic machines. The machines were contaminated for two hours using either sevoflurane 2 vol% or desflurane 6 vol%. At the end of the priming period, the patient breathing circuit and reservoir bag, carbon dioxide absorbent, sampling line and test lung were replaced with uncontaminated components. During the test period, machines were purged using oxygen flows of 10 l/minute. The average time to reach 5 ppm with the Aestiva machines was 51 minutes with sevoflurane and 71 minutes with desflurane. The average time to reach 5 ppm for the Aisys machines was 55 minutes with sevoflurane and 69 minutes with desflurane. All configurations of machines and anaesthetic gases demonstrated a rebound effect in agent concentration above 5 ppm when the fresh gas flow was subsequently reduced from 10 to 2 l/minute. Aestiva and Aisys anaesthetic machines require a prolonged period to adequately purge them of halogenated volatile anaesthetic agent. The rebound effect poses a serious concern, suggesting that after the purging period, fresh gas flows of 10 l/minute should be maintained for the duration of anaesthesia care of the malignant hyperthermia susceptible patient.

Safety of exposure of malignant hyperthermia non-susceptible patients and their relatives to anaesthetic triggering agents

As the reliability of malignant hyperthermia normal in vitro contracture test results has been questioned, this study set out to determine the reliability of malignant hyperthermia normal results in New Zealand. Three hundred and twenty-nine anaesthetics were administered to malignant hyperthermia normal patients, identified through the Palmerston North Hospital malignant hyperthermia database. Anaesthetic records were retrieved and scrutinised for a malignant hyperthermia reaction using the Malignant Hyperthermia Clinical Grading Scale. Patients were exposed to one or more of eight triggering agents and multiple anaesthetic agents were administered in 41% of cases. Six variables were analysed, and although a minority of variables were abnormal in a small number of patients, none of the findings supported a malignant hyperthermia reaction. While the analysis was limited by the adequacy of the anaesthesia records, it was supported by negative DNA analysis in 55% of patients. This study supports several previous studies in demonstrating that patients in New Zealand tested non-susceptible to malignant hyperthermia can safely be given triggering agents.

Identification and characterization of Mycobacterium tuberculosis antigens in urine of patients with active pulmonary tuberculosis: an innovative and alternative approach of antigen discovery of useful microbial molecules

Despite the clear need to control tuberculosis, the diagnosis and prevention of this serious disease are poorly developed and have remained fundamentally unchanged for more than 50 years. Here, we introduce an innovative approach to directly identify Mycobacterium tuberculosis antigens produced in vivo in humans with tuberculosis. We combined reversed phase high performance liquid chromatography and mass spectrometry and categorize four distinct M. tuberculosis proteins produced presumably in lung lesions and excreted in the urine of patients with pulmonary tuberculosis. The genes (MT_1721, MT_1694, MT_2462 and MT_3444) coding for these proteins were cloned and the recombinant molecules were produced in Escherichia coli. The proteins were recognized by immunoglobulin G antibodies from tuberculosis patients but not from non-diseased subjects. In addition, the recombinant proteins were recognized strongly by peripheral blood mononuclear cells from healthy purified protein derivative of tuberculin-positive individuals and to a lesser extent from patients with tuberculosis. These molecules are the only proteins reported to date that are derived directly from bodily fluids of tuberculosis patients, therefore are interesting candidate antigens for the development of vaccine and/or antigen detection assay for accurate diagnosis of active tuberculosis.

Malignant hyperthermia associated with exercise-induced rhabdomyolysis or congenital abnormalities and a novel RYR1 mutation in New Zealand and Australian pedigrees

Malignant hyperthermia (MH) is rarely associated with specific myopathies or musculoskeletal abnormalities. Three clinical investigations of MH associated with either non-specific myopathies or congenital disorders in three separate families are presented. Two of these cases also show evidence of exercise-induced rhabdomyolysis. In each case MH susceptibility was confirmed by in vitro contracture testing of quadriceps muscle. DNA sequence analysis of each kindred revealed the presence of a common novel mutation that results in an arginine401-cysteine substitution in the skeletal muscle ryanodine receptor gene (RYR1). Haplotype analysis using chromosome 19q markers indicated that the three families are likely to be unrelated, providing confirmation that the MH/central core disease region 1 of RYR1 is a mutation hot spot.

In vitro microtubule-based organelle transport in wild-type Dictyostelium and cells overexpressing a truncated dynein heavy chain

The transport of vesicular organelles along microtubules has been well documented in a variety of systems, but the molecular mechanisms underlying this process are not well understood. We have developed a method for preparing extracts from Dictyostelium discoideum which supports high levels of bidirectional, microtubule-based vesicle transport in vitro. This organelle transport assay was also adapted to observe specifically the motility of vesicles in the endocytic pathway. Vesicle transport can be reconstituted by recombining a high-speed supernatant with KI-washed organelles, which do not move in the absence of supernatant. Furthermore, a microtubule affinity-purified motor fraction supports robust bidirectional movement of the salt-washed organelles. The plus and minus end-directed transport activities can be separated by exploiting differences in their affinities for microtubules in the presence of 0.3 M KCl. We also used our assay to examine organelle transport in a strain of Dictyostelium overexpressing a 380-kDa C-terminal fragment of the cytoplasmic dynein heavy chain, which displays an altered microtubule pattern (380-kDa cells; [Koonce and Samso, Mol. Biol. Cell 7:935-948, 1996]). We have found that the frequency and velocity of minus end-directed membrane organelle movements were significantly reduced in 380-kDa cells relative to wild-type cells, while the frequency and velocity of plus end-directed movements were equivalent in the two cell types. The 380-kDa C-terminal fragment cosedimented with membrane organelles, although its affinity was significantly lower than that of native dynein. An impaired membrane-microtubule interaction may be responsible for the altered microtubule patterns in the 380-kDa cells.

Combined analgesia and local anesthesia to minimize pain during circumcision

BACKGROUND

Pain of circumcision is only partially relieved by single modalities, such as penile nerve block, lidocaine-prilocaine cream, and sucrose pacifiers.

OBJECTIVE

To assess the effectiveness of a combination of interventions on the pain response of infants undergoing circumcision.

METHODS

Cohort study. Group 1 included infants circumcised using the Mogen clamp and combined analgesics (lidocaine dorsal penile nerve block, lidocaine-prilocaine, acetaminophen, and sugar-coated gauze dipped in grape juice). Group 2 included infants circumcised using the Gomco clamp and lidocaine-prilocaine. Infants were videotaped during circumcision, and pain was assessed using facial activity scores and percentage of time spent crying.

RESULTS

There were 57 infants in group 1 and 29 infants in group 2. Birth characteristics did not differ between groups. Infants in group 1 were older than infants in group 2 (17 days vs 2 days) (P < .001). The mean duration of the procedure was 55 seconds and 577 seconds for infants in group 1 and 2, respectively (P < .001). Facial action scores and percentage of time spent crying were significantly lower during circumcision for infants in group 1 (P < .001). The percentage of time spent crying was 18% and 40% for infants in groups 1 and 2, respectively. No adverse effects were observed in infants in group 1; 1 infant in group 2 had a local skin infection.

CONCLUSIONS

Infants circumcised with the Mogen clamp and combined analgesia have substantially less pain than those circumcised with the Gomco clamp and lidocaine-prilocaine cream. Because of the immense pain during circumcision, combined local anesthesia and analgesia using the Mogen clamp should be considered.

Perceived efficacy and goal setting in young children

One of the central tenets of client-centred occupational therapy is to enable clients to select goals to work on in therapy (Law, 1998). The process of identifying and prioritizing goals is fairly abstract, therefore occupational therapy goals for children are often prescribed by the therapist or by parents and teachers. The purpose of this study was to pilot test a measure and a process that would provide young children with the opportunity to assess their performance on daily tasks and to establish goals for occupational therapy intervention. Parents and children completed the Perceived Efficacy and Goal Setting System (PEGS), a measure of children's perception of their competence performing fine and gross motor tasks. Children 5-9 years of age were able to discriminate among tasks and to rate whether or not they were able to perform each task competently. They were also able to use this information to select and prioritize goals for intervention. While parents often rated the child's competence lower than the child did, there was a high level of agreement regarding which tasks were difficult for the child. Parents and children often did not agree about the specific selection or priority of these tasks for intervention, however, which highlights the need for further research.

A comparison of intensive neurodevelopmental therapy plus casting and a regular occupational therapy program for children with cerebral palsy

The purpose of this research was to evaluate the combined effect of intensive neurodevelopmental therapy (NDT) and casting in improving hand function, quality of upper-extremity movement and range of motion in children aged between 18 months and 4 years with cerebral palsy (CP). A randomized crossover design was used to evaluate the difference between intensive NDT plus casting and a less intensive regular occupational therapy (OT) program. Blinded assessments of hand function, quality of upper-extremity movement, and parents' perception of hand-function performance were carried out at baseline, 4 months (end of first intervention period), 6 months (after a 2-month 'washout' period), and 10 months (end of second intervention period). Analysis of the outcomes revealed no significant differences in hand function, quality of upper-extremity movement, or parents' perception of hand-function performance between the two treatment groups-intensive NDT plus casting or regular OT programs. There does not appear to be any beneficial effect of an increased amount of therapy for the children in this study.

Gender and comorbid psychopathology in adolescents with alcohol dependence

OBJECTIVE

Although several mental disorders have been shown to be common in adolescents with substance use disorders, prior studies have not specifically focused on alcohol dependence and have not had sufficient sample sizes to examine gender effects. This study contrasts mental disorder diagnoses and symptoms between a sample of adolescents with alcohol dependence and a community control sample of adolescents and incorporates gender analyses.

METHOD

Adolescents (aged 14 years 0 months to 18 years 0 months) with alcohol dependence (females: n = 55; males: n = 78) and community-dwelling control adolescents without substance use disorders (females: n = 44; males: n = 42) were assessed by means of a semistructured interview for DSM-III-R.

RESULTS

While cannabis and hallucinogen use disorders were common in the alcohol dependence group, females and males had similar rates. Conduct disorder (CD), oppositional defiant disorder, attention-deficit hyperactivity disorder, major depression (MD), and posttraumatic stress disorder (PTSD) had significantly higher rates in the alcohol dependence than in the community control group. Depression and PTSD symptoms were more strongly associated with alcohol dependence in females than in males. A configural frequency analysis showed that CD and MD tended to occur together in both female and male adolescents with alcohol dependence.

CONCLUSIONS

While alcohol-dependent females and males similarly exhibited more comorbid disorders than control adolescents, gender affects the relationship of alcohol dependence to MD and PTSD. Rather than reflecting distinct types, the comorbid disorders of CD and MD jointly characterize many adolescents with alcohol dependence.

Pilot testing of the Canadian Occupational Performance Measure: clinical and measurement issues

The Canadian Occupational Performance Measure (COPM) is a measure of a client's self-perception of occupational performance in the areas of self-care, productivity and leisure. The COPM is administered using a semi-structured interview in which the client identifies significant issues in daily activities which are causing difficulty. Extensive pilot testing of the COPM has been completed with 268 clients in communities across Canada and in New Zealand, Greece and Britain. Results indicate the COPM has a median administration time of 30 minutes, is able to identify a wide range of occupational performance issues and appears to be responsive to changes in measurement issues centering around the interview, test construction, scoring, timing of the assessment, respondents, and the assessment process are discussed.

Risks to hearing from a rock concert

We measured noise exposure and temporary threshold shift (TTS) from a rock concert for 22 volunteers, using dosimetry, questionnaires, and audiometry. Most (81%) participants showed TTS of 10 dB or more 5 to 25 minutes after exposure; of these, 76% showed continued TTS at 40 to 60 minutes. Family physicians should counsel patients about the risks of recreational noise.

Client-centered assessment

When occupational therapists assess function or occupational performance, they must consider each person's unique needs and abilities, as well as the environmental and social factors that may be affecting the clients' performance. Therefore, occupational therapists must use evaluation tools that are individualized and sensitive to the clients' varying needs and situations. One approach to individualized evaluation is the use of a client-centered process of setting goals and assessing change. This paper describes the development of a methodology for a client-centered assessment currently being used in Canada, the Canadian Occupational Performance Measure (COPM). The conceptual model, administration and scoring procedures, and preliminary feedback to the COPM are described.

Reliability and construct validity of the Clinical Observations of Motor and Postural Skills

The Clinical Observations of Motor and Postural Skills (COMPS) is a screening tool for children with motor incoordination. A study of reliability (test-retest, interrater, and internal consistency) and construct validity with 132 children, both with and without developmental coordination disorder, is reported here. Test-retest reliability over 2 weeks was high: .92 for a group of 48 children. Interrater reliability for occupational therapists experienced in pediatrics was also excellent: .87 for a group of 72 children. Internal consistency of the COMPS was high, particularly when one of the seven items (Schilder's arm extension) was deleted. The test discriminates well between children with and without motor problems and has many properties of a good screening test.

Propofol is a 'safe' anaesthetic agent in malignant hyperthermia susceptible patients

In this study we investigated in vitro and in vivo effects of propofol in malignant hyperthermia susceptible (MHS) patients in order to assess the safety of propofol infusion as a non-triggering anaesthetic technique for diagnostic and therapeutic procedures. In vitro, human MHS muscle samples were exposed to propofol and changes in (a) baseline tension and (b) contracture tension on exposure to halothane and caffeine were measured. In vivo, (a) anaesthesia was induced in ten muscle biopsy positive MHS patients with propofol 2.5 mg/kg and (b) anaesthesia was produced in five muscle biopsy positive MHS patients with infusions of propofol up to 10 mg/kg/hr. In vitro, human MHS muscle did not develop contractures with propofol alone. Propofol had no significant effect on contracture development in response to halothane and caffeine. In vivo, no evidence of an MH response was detected following induction or maintenance of anaesthesia with propofol. Our results and literature review are in agreement that propofol is a 'safe' induction and maintenance agent in MHS patients. Propofol can be used for muscle biopsy anaesthesia because it does not alter the sensitivity of diagnostic muscle biopsy testing.

Play deprivation in children with physical disabilities: the role of the occupational therapist in preventing secondary disability

Self-initiated free play experiences are vital for the normal growth and development of all children. In this paper, children with physical disabilities who are deprived of normal play opportunities are viewed as having a second disability that hinders their potential for independent behavior and performance. Physical, social, personal, and environmental barriers that may limit the play experiences of children with physical disabilities are delineated. Studies of the interactions of these children during play are discussed, and a case is made for the promotion of active, free play in the home, the school, and the community. As facilitators of this process, occupational therapists must consider a variety of factors, including the unique capabilities of the child, the influence of parent-child and peer relationships, the role of other caregiving adults, the adaptation of toys and materials, and the impact of the environment and setting.

Occupational performance measures: a review based on the guidelines for the client-centred practice of occupational therapy

In 1987, Health and Welfare Canada and the Canadian Association of Occupational Therapists Task Force recommended that work go forward to develop an outcome measure for occupational therapy which reflects the Occupational Performance Model. The first step in this process was to review critically those outcome measures which assess occupational performance and that are currently available in the literature. This paper will present the review process, describe in more detail eight assessments that fulfilled many of the review criteria, discuss the limitations of these measures using the "Guidelines for the Client-centred Practice of Occupational Therapy as the framework, and make recommendations for the development of a new outcome measure for use in occupational therapy.

The Canadian occupational performance measure: an outcome measure for occupational therapy

The Canadian Association of Occupational Therapists, in collaboration with Health and Welfare Canada have developed and published a conceptual model for occupational therapy, the Occupational Performance model. This paper describes the development of an outcome measure, The Canadian Occupational Performance Measure (COPM), which is designed to be used with these guidelines for client-centred clinical practice. The COPM is an outcome measure designed for use by occupational therapists to assess client outcomes in the areas of self-care, productivity and leisure. Using a semi-structured interview, the COPM is a five step process which measures individual, client-identified problem areas in daily function. Two scores, for performance and satisfaction with performance are obtained. This paper describes the rationale and development of the COPM as well as information about its use for therapists.