BackgroundCardiopulmonary arrest in children is an uncommon event, and often fatal. Resuscitation is often attempted, but at what point, and under what circumstances do continued attempts to re-establish circulation become futile? The uncertainty around these questions can lead to unintended distress to the family and to the resuscitation team.ObjectivesTo define the likely outcomes of cardiopulmonary resuscitation in children, within different patient groups, related to clinical features.Data SourcesMEDLINE, MEDLINE in-Process & Other non-Indexed Citations, EMBASE, Cochrane database of systematic reviews and Cochrane central register of trials, Database of Abstracts of Reviews of Effects (DARE), the Health Technology Assessment database, along with reference lists of relevant systematic reviews and included articles.Study Eligibility CriteriaProspective cohort studies which derive or validate a clinical prediction model of outcome following cardiopulmonary arrest.Participants and InterventionsChildren or young people (aged 0 – 18 years) who had cardiopulmonary arrest and received an attempt at resuscitation, excluding resuscitation at birth.Study Appraisal and Synthesis MethodsRisk of bias assessment developed the Hayden system for non-randomised studies and QUADAS2 for decision rules. Synthesis undertaken by narrative, and random effects meta-analysis with the DerSimonian-Laird estimator.ResultsMore than 18,000 episodes in 16 data sets were reported. Meta-analysis was possible for survival and one neurological outcome; others were reported too inconsistently. In-hospital patients (average survival 37.2% (95% CI 23.7 to 53.0%)) have a better chance of survival following cardiopulmonary arrest than out-of-hospital arrests (5.8% (95% CI 3.9% to 8.6%)). Better neurological outcome was also seen, but data were too scarce for meta-analysis (17% to 71% ‘good’ outcomes, compared with 2.8% to 3.2%).LimitationLack of consistent outcome reporting and short-term neurological outcome measures limited the strength of conclusions that can be drawn from this review.Conclusions and Implications of Key FindingsThere is a need to collaboratively, prospectively, collect potentially predictive data on these rare events to understand more clearly the predictors of survival and long-term neurological outcome.Systematic Review Registration NumberPROSPERO 2013:CRD42013005102
This study was carried out to determine if exposure to hot environmental temperatures had a direct, detrimental effect on sperm quality. For this the effect of whole-body heat exposure on epididymal spermatozoa of laboratory mice was investigated. C57BL/6 mice (n = 7) were housed in a microclimate chamber at 37ºC-38ºC for 8 h per day for three consecutive days, while control mice (n = 7) were kept at 23ºC-24ºC. Cauda epididymal spermatozoa were obtained 16 h after the last heat treatment. The results showed that sperm numbers were similar in the two groups (P = 0.23), but after heat treatment, a significant reduction in the percentage of motile sperm was present (P < 0.0001). Membrane changes of the spermatozoa were investigated by staining with phycoerythrin (PE)-conjugated Annexin V, which detects exteriorization of phosphotidylserine from the inner to the outer leaflet of the sperm plasma membrane, and 7-aminoactinomycin D (7-AAD), which binds to the sperm nucleus when the plasma membrane is damaged. The percentage of spermatozoa showing positive staining with Annexin V-PE or 7-AAD or both, was significantly higher (P < 0.05) in heat-exposed mice compared with controls. These results show that whole-body heat exposure to 37ºC-38ºC induces membrane changes in the epididymal spermatozoa of mice, which may lead to apoptosis.
This study explores the potential effects of interspecific differences in breeding systems on testis organisation and sperm morphology of native murid rodents. It poses the questionwhat are the effects of depressed levels of intermale sperm competition, as indicated by small relative testes mass, on the morphology of testes and spermatozoa in murine rodents? Species from three separate murine tribes, those of the Hydromyini, Rattini and Arvicanthini, were investigated with low relative testes mass being used as a proxy for low, or non-existent, levels of intermale sperm competition. The findings show that in only one of the tribes with low relative testes mass, that of the Hydromyini, was there a reduced testicular area occupied by seminiferous tubules, but in two of the tribes significantly smaller seminiferous tubule diameters were present. In all three tribes, most species with low relative testes mass had a highly derived sperm morphology that, unlike in species with large relative testes mass, had spermatozoa where the head lacked an apical hook, was highly variable in form, often had a very large acrosome overlying the apical region of the nucleus which suggests divergent processes of sperm-egg interaction at the time of fertilisation, and a significantly shorter tail. It is therefore hypothesised that, unlike in species with a large relative testes mass where high levels of intermale sperm competition maintain a streamlined sperm head with an apical hook to aid in zona penetration, in most species of murine rodents with low relative testes mass there is greater reliance on enzymatic digestion of the extracellular matrix around the egg, and especially that of the zona pellucida, to facilitate sperm penetration at the time of fertilisation.
The plains rat, Pseudomys australis, and the spinifex hopping mouse, Notomys alexis, show marked differences in the size of their testes and in the number of spermatozoa within the epididymides. In the present study, the dynamics of sperm production and the duration of sperm transit along the male excurrent ducts were compared between these two species. The durations of the cycle of the seminiferous epithelium, spermatogenesis and sperm transit were determined by tracking cells using autoradiography after [(3)H]thymidine incorporation. Daily sperm production was determined from counts of testicular spermatids after homogenization and further estimates of sperm transit were obtained by dividing sperm reserves within the various regions of the extratesticular ducts by the daily sperm production of the attached testis. In the plains rat, the mean duration of the cycle of the seminiferous epithelium was 11.2 days, the duration of spermatogenesis was 45 days, daily sperm production was 2.6 x 10(7) spermatozoa per gram of testis and epididymal transit of spermatozoa took approximately 9 days (caput 0.8 days; corpus 1.5 days; cauda 6.5 days). In contrast, in the hopping mouse, the mean duration of the cycle of the seminiferous epithelium was 14 days, the duration of spermatogenesis was 56 days and daily sperm production per gram of testis was < 1.0 x 10(7). Epididymal transit of spermatozoa was completed in about 4 days (caput + corpus < 1 day; cauda 3 days); however, spermatozoa may be stored for an additional 1.5-2.0 days in the vas deferens. These results indicate that, in addition to small testes, the hopping mouse shows a low efficiency of sperm production, a relatively long duration of spermatogenesis and rapid passage of spermatozoa through the epididymis, all of which contribute to low epididymal sperm counts. These data are considered in relation to interspecific differences in sperm competition.
Spermatozoa from the Australian conilurine rodent, Notomys alexis, display a remarkable degree of variability in head morphology. This variation was quantified by differential counting (n= 18 animals) and image analysis (n=4 animals) of spermatozoa recovered from the cauda epididymidis and vasa deferentia. Variability in sperm morphology was exhibited in all individuals examined regardless of age. Sperm heads examined by phase contrast microscopy could be classified into four main types, and in addition, often bizarre forms occurred that ranged in shape from having a small dorsocaudal projection to being ovoid or dome-shaped. Measured by image analysis, sperm nuclear size for Notomys alexis ranged from 2.21 to 6.94 pm2 (mean 4.34 f 0.94 pm2) as compared with a range of 4.53-5.82 pm2 (mean 5.33 +_ 0.26 pm2) for spermatozoa from Pseudomys australis, a closely related species. The acrosome of Notornys alexis spermatozoa also exhibited considerable morphological variation as detected by immunolocalisation with a monoclonal antibody to a mammalian acrosomal antigen. This variability exhibited by both the acrosome and the nucleus of the sperm head in Notomys alexis may relate to low levels of intermale sperm competition that probably occurs in these animals.
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