Peak oxygen uptake in relation to growth and maturation in 11- to 17–year-old humans

This study used multilevel modelling to examine peak oxygen uptake ( ) during growth and maturation. Body mass, stature, triceps and subscapular skinfold thicknesses, blood haemoglobin concentration, and of boys and girls, [mean (SD)] aged 11.1 (0.4) years at the onset of the study, were measured at ages 11, 12, 13 and 17 years. Sexual maturation was assessed on the first three occasions and was assumed to be Tanner stage 5 at 17 years. The analysis was founded on 388 determinations from 132 children. The initial model revealed mass, stature and age as significant explanatory variables of with an additional positive effect for stage of maturity. Girls' values were significantly lower than those of boys and a significant age-by-sex interaction described a progressive divergence in boys' and girls' . The introduction of skinfold thicknesses produced a model with an improvement in fit. The stature term was negated and the mass exponent almost doubled. The sex and age-by-sex terms were reduced but remained significant. Many of the observed maturity effects were explained with stage 5 becoming non-significant. Blood haemoglobin concentration was a nonsignificant parameter estimate in both models. Fat-free mass was the dominant influence on the growth of but the multilevel regression models demonstrated that, with body size and fatness allowed for, increased with age and maturation in both sexes. Electronic Publication     

Key factors in children’s competence to consent to clinical research

Background

Although law is established on a strong presumption that persons younger than a certain age are not competent to consent, statutory age limits for asking children’s consent to clinical research differ widely internationally. From a clinical perspective, competence is assumed to involve many factors including the developmental stage, the influence of parents and peers, and life experience. We examined potential determining factors for children’s competence to consent to clinical research and to what extent they explain the variation in competence judgments.

Methods

From January 1, 2012 through January 1, 2014, pediatric patients aged 6 to 18 years, eligible for clinical research studies were enrolled prospectively at various in- and outpatient pediatric departments. Children’s competence to consent was assessed by MacArthur Competence Assessment Tool for Clinical Research. Potential determining child variables included age, gender, intelligence, disease experience, ethnicity and socio-economic status (SES). We used logistic regression analysis and change in explained variance in competence judgments to quantify the contribution of a child variable to the total explained variance. Contextual factors included risk and complexity of the decision to participate, parental competence judgment and the child’s or parents decision to participate.

Results

Out of 209 eligible patients, 161 were included (mean age, 10.6 years, 47.2 % male). Age, SES, intelligence, ethnicity, complexity, parental competence judgment and trial participation were univariately associated with competence (P?<?0.05). Total explained variance in competence judgments was 71.5 %. Only age and intelligence significantly and independently explained the variance in competence judgments, explaining 56.6 % and 12.7 % of the total variance respectively. SES, male gender, disease experience and ethnicity each explained less than 1 % of the variance in competence judgments. Contextual factors together explained an extra 2.8 % (P?>?0.05).

Conclusions

Age is the factor that explaines most of to the variance in children’s competence to consent, followed by intelligence. Experience with disease did not affect competence in this study, nor did other variables.

Clinical trial registration

Development and use of a standardized instrument for assessing children’s competence to consent in drug trials: Are legally established age limits valid?, NTR3918.

     

Morphological changes in the skin in response to external α-irradiation

Summary The author studied the changes occurring in the skin of the rabbit in external alpha-irradiation. The latter has a pronounced injurious effect, the morphological manifestations of which are analogous to those observed in the action of other types of ionizing radiation. Besides this, the reaction of the alpha-irradiated tissue has a specific feature in the form of a sharp contrast between the degree of affection of the superficial and deep layers. The injury mostly involves the epidermis. This is due to the physical properties of alpha-radiation.Presented by Active Member AMN SSSR I. G. Rufanov     

Altered uterine contractility in response to β-adrenoceptor agonists in ovarian cancer

We aimed to prospectively examine β-adrenoceptor-mediated uterine contractility in women suffering from gynecological malignancies. Myometrial specimens were obtained from non-pregnant women undergoing hysterectomy for benign gynecological disorders, and ovarian, endometrial, synchronous ovarian–endometrial, and cervical cancer. Contractions of myometrial strips in an organ bath before and after cumulative dosages of β₂- and β₃-adrenoceptor agonists with preincubation of propranolol, SR 59230A, and butoxamine were studied. All agonists induced a dose-dependent attenuation for uterine contractility in endometrial or cervical cancer, similar to that observed in the reference group. Contradictory effects were observed for ovarian cancer alone or in combination with endometrial cancer. CL 316243 or ritodrine abolished the relaxation, whereas BRL 37344 increased the uterine contractility in ovarian cancer. Moreover, β-adrenoceptor antagonists caused varied effects for β₂- or β₃-adrenoceptor agonists. Our experiments demonstrate that ovarian cancer, alone or as synchronous ovarian–endometrial cancer, substantially alters uterine contractility in response to β-adrenoceptor agonists.     

Are age-related increases in force variability due to decrements in strength?

The purpose of this investigation was to examine the relationship between strength and the magnitude and time sequential structure of force variability. Young and old adults produced isometric force via index finger abduction to a visually presented target corresponding to a constant force level of 5 or 25% maximal voluntary contraction (MVC). Cluster analysis was used to divide subjects into groups based on age and strength. The variability of older adults was greater and showed more time dependent structure than their younger counterparts. The force output of weaker subjects was also more variable and had a stronger sequential structure. Indeed, when MVC was controlled for there was no significant age effect on force variability. The relationship between strength and variability remained significant, however, when chronological age was controlled for. The findings revealed that the established age-related changes in force variability are more fundamentally due to the association between strength and force variability and provide a further challenge to using chronological age as a marker of the biological aging process in studies of motor control.     

What contributes to depression in Parkinson's disease?

BACKGROUND: Depression is a common problem in patients with Parkinson's disease, but its mechanism is poorly understood. It is thought that neurochemical changes contribute to its occurrence, but it is unclear why some patients develop depression and others do not. Using a community-based sample of patients with Parkinson's disease, we investigated the contributions of impairment, disability and handicap to depression in Parkinson's disease. METHODS: Ninety-seven patients seen in a population-based study on the prevalence of Parkinson's disease completed the Beck Depression Inventory (BDI). Clinical and historical information on symptoms and complications of Parkinson's disease were obtained from the patients by a neurologist. In addition, clinician and patient ratings of disability on the Schwab and England scale were obtained and a quality of life questionnaire was completed. RESULTS: Moderate to severe depression (BDI > or = 18) was reported by 19.6% of the patients. Higher depression scores were associated with advancing disease severity, recent self-reported deterioration, higher akinesia scores, a mini-mental score of < 25 and occurrence of falls. Disability as rated by the neurologist accounted for 34% of the variance of depression scores. Self-reported impairment of cognitive function and the feeling of stigmatization accounted for > 50% of the variance of depression scores. CONCLUSIONS: Depression in patients with Parkinson's disease is associated with advancing disease severity, recent disease deterioration and occurrence of falls. Regression analysis suggests that depression in Parkinson's disease is more strongly influenced by the patients' perceptions of handicap than by actual disability. The treatment of depression should therefore be targeted independently of treatment of the motor symptoms of Parkinson's disease, and consider the patients' own perception of their disease.     

How to estimate overweight in pubescent asthmatics?

PurposeThe purpose of our research was to compare the body mass index (BMI) and selected anthropometric parameters in asthmatic and non-asthmatic pubescents.Material and MethodsThe study group consisted of 64 asthmatic boys and 45 girls; the control group consisted of 68 non-asthmatic boys and 48 non-asthmatic girls. All the children were 12–14 years old.We measured anthropometric parameters by a standardized method and the percentage of fat using the simple 2-site skinfold method. Additionally, we calculated the percentage of body composition (Matiegka) and the components of somatotype (Heath-Carter). Statistical significance was estimated at the level of p<0.05 by ANOVA test.ResultsThe asthmatic boys were significantly shorter than the non-asthmatic (p=0.015), however, we did not find any significant differences in weight and/or BMI in boys nor girls. The asthmatic boys had significantly higher fat mass % than the non-asthmatic ones (p<0.001). Moreover, they had significantly lower muscle mass % (p<0.001) as well as the bone mass % (p<0.001). The asthmatic girls had higher fat mass % than the non-asthmatic ones (p=0.028) and lower muscle mass % (p<0.001). The simple 2-site skinfold method also showed higher fat % in the asthmatic boys (p<0.001) but not in the girls. Examining the Heath-Carter somatotype components, the higher endomorphy was the only significant difference in asthmatic boys (p<0.001) and near significant in asthmatic girls (p=0.053).ConclusionExamination of the BMI alone is not sufficient in asthmatic children because of their high percentage of fat. That is why additionally testing fat % is recommended.     

Changes of sleep EEG slow-wave activity in response to sleep manipulations: to what extent are they related to changes in REM sleep latency?

SUMMARY  Sleep interventions may have direct effects on slow-wave activity (SWA, i.e. power of the sleep EEG signal in the 0.75-4.5 Hz range) as well as indirect ones caused by changes in REM sleep (REMS) latency. The effects of changes in REMS latency on SWA were investigated by analysing simulations with a mathematical model. Mean SWA in the first non-REMS episode shows an initial increase and a later decline as a function of REMS latency. In the second non-REMS episode, mean SWA decreases with increasing REMS latency. These results of the simulations were validated with experimental data.
In the evaluation of the effects of sleep interventions on SWA the effects of the timing of REMS have to be accounted for. The analysis of SWA over a sufficiently long constant amount of time spent in non-REMS proves to be relatively independent of REMS latency, which allows conclusions about the effects of sleep interventions on SWA per se.     

Dendritic cells adhere to and transmigrate across lymphatic endothelium in response to IFN-α

Migration of DC into lymphatic vessels ferries antigenic cargo and pro-inflammatory stimuli into the draining LN. Given that tissues under the influence of viral infections produce type I IFN, it is conceivable that these cytokines enhance DC migration in order to facilitate an antiviral immune response. Cultured lymphatic endothelium monolayers pretreated with TNF-α were used to model this phenomenon under inflammatory conditions. DC differentiated in the presence of either IFN-α2b or IFN-α5 showed enhanced adhesion to cultured lymphatic endothelial cells. These pro-adhesive effects were mediated by DC, not the lymphatic endothelium, and correlated with increased DC transmigration across lymphatic endothelial cell monolayers. Transmigration was guided by chemokines acting on DC, and blocking experiments with mAb indicated a role for LFA-1. Furthermore, incubation of DC with IFN-α led to the appearance of active conformation epitopes on the CD11a integrin chains expressed by DC. Differentiation of mouse DC in the presence of IFN-α also increased DC migration from inflammed footpads toward popliteal LN. Collectively, these results indicate a role for type I IFN in directing DC toward LN under inflammatory conditions.     

Does psychotherapy homework lead to improvements in depression in cognitive-behavioral therapy or does improvement lead to increased homework compliance?

The bidirectional causal relationships between psychotherapy homework (HW) compliance and changes in depression were assessed in 2 groups of depressed outpatients treated with cognitive-behavioral therapy using nonrecursive structural equation modeling techniques. The data were consistent with the hypothesis that HW compliance had a causal effect on changes in depression, and the magnitude of this effect was large. Patients who did the most HW improved much more than patients who did little or no HW. In contrast, depression severity did not appear to influence HW compliance. HW compliance did not appear to be a proxy for any other, unobserved (3rd) variable, such as motivation. Although the causal effect of HW on depression was large, the correlation between HW and depression was small. Some possible explanations, along with suggestions for future studies, are proposed.     

Deficits in adaptive upper limb control in response to trunk perturbations in Parkinson’s disease

The ability of patients with Parkinsons disease (PD) to compensate for unexpected perturbations remains relatively unexplored. To address this issue PD subjects were required to compensate at the arm for an unexpected mechanical perturbation of the trunk while performing a trunk-assisted reach. Twelve healthy and nine PD subjects (off medication) performed trunk-assisted reaching movements without vision or knowledge of results to a remembered target in the ipsilateral (T1) or contralateral (T2) workspace. On 60% of the trials trunk motion was unrestrained (free condition). On the remaining 40% of randomly selected trials trunk motion was arrested at movement onset (blocked condition). If subjects appropriately changed arm joint angles to compensate for the trunk arrest, there should be spatial and temporal invariance in the hand trajectories and in the endpoint errors across conditions. The control group successfully changed their arm configuration in a context-dependent manner which resulted in invariant hand trajectory profiles across the free and blocked conditions. More so, they initiated these changes rapidly after the trunk perturbation (group mean 70 ms). Some PD subjects were unable to maintain invariant hand paths and movement errors across conditions. Their hand velocity profiles were also more variable relative to those of the healthy subjects in the blocked-trunk trials but not in the free-trunk trials. Furthermore, the latency of compensatory changes in arm joint angles in movements toward T1 was longer in the PD group (group mean 153 ms). Finally, PD subjects arm and trunk were desynchronized at movement onset, confirming our previous findings and consistent with PD patients known problems in the sequential or parallel generation of different movement components. The findings that individual PD subjects were unsuccessful or delayed in producing context-dependent responses at the arm to unexpected perturbations of the trunk suggests that the basal ganglia are important nodes in the organization of adaptive behavior.     

How many cases need to be reviewed to compare performance in surgical pathology?

Recent studies have shown increased interest in measuring error rates in surgical pathology. We sought to determine how many surgical pathology cases need to be reviewed to show a significant difference from published error rates for review of routine or biopsy cases. Results of 4 series with this type of diagnostic material involving a total of 11,683 cases were reviewed to determine the range of published false-negative, false-positive, typing error, threshold error, and clinically significant error rates. Error rates ranged from 0.00% to 2.36%; clinically significant error rates ranged from 0.34% to 1.19%. Assuming a power of 0.80 and a 1-sided alpha of 0.05, the number of cases needed to be reviewed to show that a laboratory with either twice or one half the published error rate was significantly different from the range of published error rates varied from 3.30 to 50, 158. For clinically significant errors, the number of cases varied from 665 to 5,886. Because the published error rates are low, a relatively large number of cases need to be reviewed and a relatively great difference in error rate needs to exist to show a significant difference in performance in surgical pathology.     

Lethal shock in irradiated rabbits in response to administration of homologous γ-globulin

Summary A solution of homologous -globulin (50 mg in 10 ml of physiological saline) was injected intravenously in rabbits 1 h after the irradiation with 800 r. Eight of 9 rabbits died of shock soon after the injection, although the same dose of the preparation did not result in shock when injection was administered 3 days after exposure to irradiation of healthy animals. The author explains the findings by a varying reactivity of the irradiated organism at various phases of radiation sickness, and by the importance of higher -globulin concentrations in the blood for the advent of shock.Presented by N. A. Kraevskii Active Member, Academy of Medical Sciences, USSR Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 58, No. 10, pp. 31–33, October, 1964     

Sensitivity to ether anesthesia and to γ-rays in mutagen-sensitive strains of Drosophila melanogaster

An ether-resistant strain of Drosophila melanogaster, Eth-29, has previously been found to be radiosensitive. Some mutagen-sensitive strains are known to be hypersensitive to X-rays in larvae. The correlation between sensitivities to ether anesthesia and to y-rays was examined in adult flies of 12 mutagen-sensitive strains and 6 control strains. A wide variation in sensitivities to ether anesthesia, γ-ray knock-down and γ-ray lethality was demonstrated. No correlation between DNA-repair capacity and ether sensitivity or γ-ray knock-down sensitivity was shown. Only mei-9 and mus201, which are deficient in excision repair, as well as Eth-29 were found to be sensitive to γ-ray lethality. These findings indicate that the targets for ether anesthesia, knock-down and lethality may be different. Lethality appears to be caused by DNA damage, while the other 2 endpoints appear not to be related to DNA damage.     

Adjusting reach to lift movements to sudden visible changes in target’s weight

People can adjust their reach-to-grasp movements online to sudden changes in the spatial properties of a target. We investigated whether they can also do this when a non-spatial property, weight, suddenly changes. Guiding your movement by using visual cues about an object’s weight depends heavily on experience and is expected to be processed by the (slow) ventral stream rather than the (fast) ‘online control’ dorsal stream. In the first experiment, participants reached out and lifted an object with an expected or an unexpected weight. As predicted, there was an effect of expected weight on the time between the end of the reaching phase and the object’s lift-off. In the second experiment, the object sometimes visibly changed weight after the participants had started their movement. The lifting time did not depend on whether the object had changed weight. Thus, participants can make online adjustments to a visually indicated change in weight. These results are interpreted as being contrary to existing theories of online control.