Age-related changes in tactile spatial resolution from 6 to 16 years old

The aim of this study was to determine age-related changes in tactile spatial resolution from 6 to 16 years old. Two hundred and twenty-two healthy children (105 boys and 117 girls) were assessed. The tactile spatial resolution threshold was determined using a classic set of JVP domes with a procedure adapted for children. Preadolescence appears to be an important step in tactile spatial resolution since children aged between 6 and 9 years old had a worse tactile spatial resolution than older children. Both peripheral and central explanations for this improvement of tactile spatial resolution with age are considered. The authors suggest that cortical maturational processes are likely to explain the better results of older children.     

Age differences in tactile pattern recognition at the fingertip

Young (21-26 years, n=20) and old (55-86 years, n=25) participants were tested for their ability to recognize raised letters (6-mm high, 1-mm relief) by touch. Spatial resolution thresholds were also measured with grating domes to derive an index of the degree of afferent innervation at the fingertip. Letter recognition in the young group was very consistent and highly accurate (mean, 86% correct), contrasting with the performance of the old group, which was more variable and comparatively low in accuracy (mean, 53% correct). In both groups, spatial resolution thresholds accounted for a substantial portion of the variance in the performance, suggesting a strong link between age-dependent variations in tactile innervation and recognition accuracy. The patterns of errors in the old group showed that an inability to encode internal elements specific to certain letters was at the source of most confusion among letters. Whether this inability reflected only deficient peripheral encoding mechanisms or some other alterations at the central level is discussed.     

Tactile spatial acuity in elderly persons: assessment with grating domes and relationship with manual dexterity

In this study, we sought to better define the limit of spatial resolution at the fingertips of elderly participants (n = 30, age 60-95 years) using an extended set of JVP grating domes, incorporating four new grating dimensions (2.5-, 3.5-, 4.0- and 4.5-mm width). A secondary aim was to examine whether deficits in tactile acuity could be related to hand dysfunction in older adults. Spatial resolution thresholds were determined by the finest grating whose orientation (dominant index finger) could be reported reliably. Manual dexterity was assessed with the Grooved Pegboard Test (GPT). The extended set of domes improved threshold measurements in a majority of participants (21/30). Still, accurate threshold estimates could not be obtained in one third of the participants, mostly in the older age group (8/9, 74-95 years). Grating resolution thresholds at the index finger were strongly correlated (r = 0.66, p<0.01) with dexterity scores derived from the GPT. From these results, we conclude that the 2.5- and 3.5-mm grating domes are suitable additions when assessing spatial acuity at the fingertips of older subjects between 60 and 70 years of age (mean threshold, 2.7+/-0.6 mm). For the older ones, the 4.0- and 4.5-mm domes can improve threshold measurements but interpretation of values can be complicated by the presence of undiagnosed pathologies (e.g., diffuse polyneuropathy) as people advance in age. The strong relationship between grating resolution thresholds and dexterity scores indicates that an impaired spatial acuity at the fingertips may translate into great difficulties in tasks requiring fine manipulations. These findings have important implications for the assessment of hand function in older adults.     

Age differences in tactile pattern recognition at the fingertip

Young (21–26 years, n?=?20) and old (55–86 years, n?=?25) participants were tested for their ability to recognize raised letters (6-mm high, 1-mm relief) by touch. Spatial resolution thresholds were also measured with grating domes to derive an index of the degree of afferent innervation at the fingertip. Letter recognition in the young group was very consistent and highly accurate (mean, 86% correct), contrasting with the performance of the old group, which was more variable and comparatively low in accuracy (mean, 53% correct). In both groups, spatial resolution thresholds accounted for a substantial portion of the variance in the performance, suggesting a strong link between age-dependent variations in tactile innervation and recognition accuracy. The patterns of errors in the old group showed that an inability to encode internal elements specific to certain letters was at the source of most confusion among letters. Whether this inability reflected only deficient peripheral encoding mechanisms or some other alterations at the central level is discussed.     

Tactile Spatial Acuity in Childhood: Effects of Age and Fingertip Size

Tactile acuity is known to decline with age in adults, possibly as the result of receptor loss, but less is understood about how tactile acuity changes during childhood. Previous research from our laboratory has shown that fingertip size influences tactile spatial acuity in young adults: those with larger fingers tend to have poorer acuity, possibly because mechanoreceptors are more sparsely distributed in larger fingers. We hypothesized that a similar relationship would hold among children. If so, children’s tactile spatial acuity might be expected to worsen as their fingertips grow. However, concomitant CNS maturation might result in more efficient perceptual processing, counteracting the effect of fingertip growth on tactile acuity. To investigate, we conducted a cross-sectional study, testing 116 participants ranging in age from 6 to 16 years on a precision-controlled tactile grating orientation task. We measured each participant''s grating orientation threshold on the dominant index finger, along with physical properties of the fingertip: surface area, volume, sweat pore spacing, and temperature. We found that, as in adults, children with larger fingertips (at a given age) had significantly poorer acuity, yet paradoxically acuity did not worsen significantly with age. We propose that finger growth during development results in a gradual decline in innervation density as receptive fields reposition to cover an expanding skin surface. At the same time, central maturation presumably enhances perceptual processing.     

Noninformative vision improves the spatial resolution of touch in humans

Research on sensory perception now often considers more than one sense at a time. This approach reflects real-world situations, such as when a visible object touches us. Indeed, vision and touch show great interdependence: the sight of a body part can reduce tactile target detection times [1], visual and tactile attentional systems are spatially linked [2], and the texture of surfaces that are actively touched with the fingertips is perceived using both vision and touch [3]. However, these previous findings might be mediated by spatial attention [1, 2] or by improved guidance of movement [3] via visually enhanced body position sense [4--6]. Here, we investigate the direct effects of viewing the body on passive touch. We measured tactile two-point discrimination thresholds [7] on the forearm while manipulating the visibility of the arm but holding gaze direction constant. The spatial resolution of touch was better when the arm was visible than when it was not. Tactile performance was further improved when the view of the arm was magnified. In contrast, performance was not improved by viewing a neutral object at the arm's location, ruling out improved spatial orienting as a possible account. Controls confirmed that no information about the tactile stimulation was provided by visibility of the arm. This visual enhancement of touch may point to online reorganization of tactile receptive fields.     

Comparison of the influenza virus-specific effector and memory B-cell responses to immunization of children and adults with live attenuated or inactivated influenza virus vaccines

Cellular immune responses to influenza virus infection and influenza virus vaccination have not been rigorously characterized. We quantified the effector and memory B-cell responses in children and adults after administration of either live attenuated (LAIV) or inactivated (TIV) influenza virus vaccines and compared these to antibody responses. Peripheral blood mononuclear cells were collected at days 0, 7 to 12, and 27 to 42 after immunization of younger children (6 months to 4 years old), older children (5 to 9 years old), and adults. Influenza virus-specific effector immunoglobulin A (IgA) and IgG circulating antibody-secreting cells (ASC) and stimulated memory B cells were detected using an enzyme-linked immunospot assay. Circulating influenza virus-specific IgG and IgA ASC were detected 7 to 12 days after TIV and after LAIV immunization. Seventy-nine percent or more of adults and older children had demonstrable IgG ASC responses, while IgA ASC responses were detected in 29 to 53% of the subjects. The IgG ASC response rate to LAIV immunization in adults was significantly higher than the response rate measured by standard serum antibody assays (26.3% and 15.8% by neutralization and hemagglutination inhibition assays, respectively). IgG ASC and serum antibody responses were relatively low in the younger children compared to older children and adults. TIV, but not LAIV, significantly increased the percentage of circulating influenza virus-specific memory B cells detected at 27 to 42 days after immunization in children and adults. In conclusion, although both influenza vaccines are effective, we found significant differences in the B-cell and antibody responses elicited after LAIV or TIV immunization in adults and older children and between young children and older age groups.     

Tactile sensitivity,tactile acuity,and affective touch: from childhood to early adolescence

The development of somatosensation and affective touch acquires a central role throughout our lives, for several reasons. In adults, these functions are driven by different, neuroanatomically and functionally segregated fibres. To date, very little is known about the basic features of these fibres in childhood and this lack of knowledge is mirrored in the affective touch domain, where there are no studies on the main physiological features of the tactile processes linked to the stimulation of the hairy skin, namely the preferential site of affective touch. Thus, our study aims to analyze (1) tactile sensitivity and tactile acuity of children’s hairy forearms; (2) a possible dissociation between somatosensation and the affective touch; and (3) the presence/absence of the perception of affective touch already in childhood. To these aims, participants (160 children, aged 6 to 14?years), were administered with the Von Frey (tactile sensitivity) and the 2 Point Discrimination (tactile acuity) tests. Affective touch was measured following the classic protocol and pleasantness ratings were recorded. Our findings showed a correlation between age and somatosensation, suggesting a progressive reduction of sensitivity and acuity as age grows. Further, there was no overlap between affective touch and somatosensation, suggesting a behavioural segregation. Lastly, we found higher pleasantness ratings for Affective versus Neutral stimulations at all ages and an enhanced preference for Affective as age grows. We concluded that both somatosensation and affective touch are already present as two separate components of touch in childhood and change as a function of age.     

Usefulness and limitation of measurement of insulin-like growth factor binding protein-3 (IGFBP-3) for diagnosis of growth hormone deficiency.

To analyze the utility of insulin-like growth factor binding protein-3 (IGFBP-3) radioimmunoassay for diagnosis of growth hormone deficiency (GHD) we measured IGFBP-3 in sera from normal children, short children and patients with GHD. The sensitivity (true positive ratio) of IGFBP-3 for complete GHD (cGHD) was 93%, while the specificity (true negative ratio) for normal short children (NS) was 88%. In contrast, the sensitivity of IGFBP-3 for partial GHD (pGHD) was only 43%. The poor discrimination between patients with pGHD and NS may be the result of their relatively similar GH level, as compared to cGHD, or due to the limitations of GH stimulation tests. The specificity of IGFBP-3 for NS was excellent in children of all ages: less than 10 years old (87%) and older than 10 (88%). However, sensitivity for GHD was good for children less than 10 years old (84%) but poor for children older than 10 (64%). IGFBP-3 may be less sensitive for diagnosing GHD in older children because IGFBP-3 levels may also increase during puberty due to mechanisms independent of the GH-IGF-I axis.     

Intestinal parasites in Kampuchea, Takeo Province

Fresh stool samples obtained from 1407 adult patients who sought treatment in Takeo province hospital and 332 Takeo preschool and school-age children from 3 to 18 years of age were examined for the presence of intestinal parasites using the technique of native preparation and the flotation method of Faust with subsequent staining with Lugol solution to demonstrate cysts. In hospital patients, a total of 13 protozoan and 9 helminth species were diagnosed. The prevalence of Entamoeba histolytica (cysts and trophozoites) was highest in the age group 15-18 years (18.3%), the peak prevalence of Gairdia lamblia (27.6%) occurred in children of the age group 6-9 years. The highest frequency distribution of Pentatrichomonas hominis (20.1%) was recorded in 3 to 5 years old, that of Enteromonas hominis (12.8%) in 6 to 9 years old. The predominant helminth was Ancylostoma duodenale, with the peak prevalence (65.2%) in patients older than 18 years, followed by Ascaris lumbricoides and Strongyloides stercoralis. Almost half of children patients under 6 was infected with at least two species of parasites, patients over 6 were infected simultaneously with two or more intestinal parasites in an absolute majority of cases. In Takeo preschool and school children the spectrum of diagnosed protozoan and helminth species was somewhat narrower than seen in hospital patients, but their prevalence rates were higher, except for the flagellate Pentatrichomonas hominis. The highest prevalence rates recorded were for E. histolytica 29.5% (age category 10-14 years), for G. lamblia 34.8% (age category 6-9 years), for P. hominis 19.3% (age category 3-5 years), for E. hominis 10.5% (age category 3-5 years), for A. duodenale 85.9% (age category 15-18 years), for A. lumbricoides 26.1% (age category 6-9 years), and for S. stercoralis 18.8% (age category 6-9 years). As many as 70% of children at the age between 6 and 15 years were simultaneously infected with two or three species of intestinal parasites.     

Body mass index, prevalence of overweight and obesity in Lithuanian children and adolescents, 1985-2002

The study provides the body mass index (BMI), the prevalence of overweight (OW) and obesity (OB) in Lithuanian children and adolescents, 1985-2002. In the 2000-2002 more than 9000 schoolchildren of 7-18 years old were investigated in the 5 biggest towns and surrounding settlements of Lithuania. These data were compared with the 1985 data. The prevalence of OW and OB was estimated using the International Obesity Task Force (IOTF) cut-off points. The prevalence of OW in Lithuanian children and adolescents was higher among younger schoolchildren in comparison with older adolescents. OW was lower among the older girls in comparison with the older boys: 4.60%-11.50%/4.80%0-13.62% in the 7-13 years girls/boys, versus 1.50%-6.60%/3.90%-9.50% in the 14-18 years old girls/boys. The prevalence of OW among younger Lithuanian adolescents did not change significantly in the last 15 years, but it slightly decreased in older boys and demonstrably diminished in older adolescent girls. In generally, the prevalence of OW among Lithuanian adolescents is low in comparison with the prevalence of OW in children from the other countries.     

Prevalence of enterotoxigenic Bacteroides fragilis in patients with diarrhea: a controlled study

In this age matched controlled study performed in Malatya, a city in east region of Turkey, enterotoxigenic Bacteroides fragilis (ETBF) was investigated in stool specimens obtained from children and adults with and without diarrhea. A nested polymerase chain reaction (PCR) method was used to detect the enterotoxin gene of B. fragilis in a total of 418 stool samples, including 221 samples from 117 children (aged 0-16 years) and 104 adults (aged >16 years) with diarrhea, and 197 samples from 102 children and 95 adults as control group that was the same age group with those having diarrhea. ETBF was detected in 13 of 117 diarrheal children (11.1%) and 8 of 102 control children (7.8%) (P>0.05). In children aged 1-5 years, the rate of ETBF was significantly higher in patients than in controls (25% versus 9.5%, respectively; P<0.05). On the other hand ETBF was detected similar rates (2.2% and 2.4%, respectively) in children younger than 1 year in both patients and controls. ETBF positivity was not significantly difference between patient and control groups who were older than 5 years of age and adults. The frequency of ETBF in the controls was slightly higher in older persons than in younger ones; however, it was not significant. The rate of ETBF as the only enteropathogen in the patients with ETBF was significantly higher than in controls with ETBF (88% versus 39%, respectively; P<0.02). We found that in east region of Turkey, the prevalence of ETBF was higher in the childhood diarrhea, particularly in aged 1-5. As the only enteropathogen, ETBF may play an important role in diarrheal diseases. Persons after 6 years old can be carrier for ETBF regardless diarrhea.     

Schistosoma haematobium treatment in 1-5 year old children: safety and efficacy of the antihelminthic drug praziquantel

Background

Morbidity due to schistosomiasis is currently controlled by treatment of schistosome infected people with the antihelminthic drug praziquantel (PZQ). Children aged up to 5 years are currently excluded from schistosome control programmes largely due to the lack of PZQ safety data in this age group. This study investigated the safety and efficacy of PZQ treatment in such children.

Methods

Zimbabwean children aged 1–5 years (n = 104) were treated with PZQ tablets and side effects were assessed by questionnaire administered to their caregivers within 24 hours of taking PZQ. Treatment efficacy was determined 6 weeks after PZQ administration through schistosome egg counts in urine. The change in infection levels in the children 1–5 years old (n = 100) was compared to that in 6–10 year old children (n = 435).

Principal Findings

Pre-treatment S. haematobium infection intensity in 1–5 year olds was 14.6 eggs/10 ml urine and prevalence was 21%. Of the 104 children, 3.8% reported side effects within 24 hours of taking PZQ treatment. These were stomach ache, loss of appetite, lethargy and inflammation of the face and body. PZQ treatment significantly reduced schistosome infection levels in 1–5 year olds with an egg reduction rate (ERR) of 99% and cure rate (CR) of 92%. This was comparable to the efficacy of praziquantel in 6–10 year olds where ERR was 96% and CR was 67%.

Interpretation/Significance

PZQ treatment is as safe and efficacious in children aged 1–5 years as it is in older children aged 6–10 years in whom PZQ is the drug of choice for control of schistosome infections.     

Providing information about a flavor to preschoolers: effects on liking and memory for having tasted it

This study sought to determine if providing affectively positive information about a flavor to preschool-aged children during tasting will increase recognition of and liking for the flavor and if the recognition and liking are associated. Forty-six 3- to 6-year-old children tasted 10 flavors: 5 presented with affectively positive information and 5 without. The 10 flavors were then presented again interspersed with 10 distracter flavors. Children reported whether they had tasted the flavor previously and provided hedonic ratings for each flavor. Children's ability to remember having tasted a flavor was greater when the flavor was presented with affectively positive information than without in children throughout the age range of 3-6 years. In children younger than 4.5 years, the provision of information had no effect on hedonic rating, whereas in older children, the provision of information was associated with greater hedonic ratings. We conclude that providing affectively positive information to children about a flavor can increase their ability to recognize the flavor as previously tasted and increases hedonic rating of the flavor in children older than 4.5 years.     

Predicting future community-level ocular Chlamydia trachomatis infection prevalence using serological,clinical, molecular,and geospatial data

Trachoma is an infectious disease characterized by repeated exposures to Chlamydia trachomatis (Ct) that may ultimately lead to blindness. Efficient identification of communities with high infection burden could help target more intensive control efforts. We hypothesized that IgG seroprevalence in combination with geospatial layers, machine learning, and model-based geostatistics would be able to accurately predict future community-level ocular Ct infections detected by PCR. We used measurements from 40 communities in the hyperendemic Amhara region of Ethiopia to assess this hypothesis. Median Ct infection prevalence among children 0–5 years old increased from 6% at enrollment, in the context of recent mass drug administration (MDA), to 29% by month 36, following three years without MDA. At baseline, correlation between seroprevalence and Ct infection was stronger among children 0–5 years old (ρ = 0.77) than children 6–9 years old (ρ = 0.48), and stronger than the correlation between active trachoma and Ct infection (0-5y ρ = 0.56; 6-9y ρ = 0.40). Seroprevalence was the strongest concurrent predictor of infection prevalence at month 36 among children 0–5 years old (cross-validated R² = 0.75, 95% CI: 0.58–0.85), though predictive performance declined substantially with increasing temporal lag between predictor and outcome measurements. Geospatial variables, a spatial Gaussian process, and stacked ensemble machine learning did not meaningfully improve predictions. Serological markers among children 0–5 years old may be an objective tool for identifying communities with high levels of ocular Ct infections, but accurate, future prediction in the context of changing transmission remains an open challenge.     

Decline of tactile acuity in aging: a study of body site,blood flow,and lifetime habits of smoking and physical activity

Tactile acuity of 60 older subjects (≥?65 years) and 19 younger subjects (18–28 years) was assessed by two-point gap thresholds at the upper and lower surfaces of the forefinger, at the upper and lower surfaces of the feet, and at the volar surface of the forearm. The older subjects were assigned to one of four groups of 15 subjects each, depending on reported lifetime habits of physical activity and smoking: (1) active smokers, (2) active nonsmokers, (3) inactive smokers, and (4) inactive nonsmokers. Peripheral blood flow was assessed at the forefinger, foot, and forearm by means of laser-Doppler imaging and skin temperature recordings, under resting conditions and during and after a 5-min exposure to mild cooling (28°C). Consistent with previous studies, tactile acuity thresholds in the foot and finger averaged about 80% higher in the older subjects than in the younger subjects, but only about 22% higher in the forearm. Although the upper surface of the fingertip was more sensitive than the lower surface in both younger and older subjects, the age-related decline in tactile acuity was nearly identical on both sides of the finger and foot. The latter finding refutes the hypothesis that the larger effect of aging in the extremities results from greater physical wear and tear on the contact surfaces of the hands and feet. Self-reported lifetime histories of physical activity and smoking were not significantly associated with measures of cutaneous blood flow or tactile thresholds. Possible reasons for this lack of association are discussed, including the inherent limitations of testing only healthy older subjects, and the concept of “successful aging”.     

Decline of tactile acuity in aging: a study of body site, blood flow, and lifetime habits of smoking and physical activity

Tactile acuity of 60 older subjects (> or = 65 years) and 19 younger subjects (18-28 years) was assessed by two-point gap thresholds at the upper and lower surfaces of the forefinger, at the upper and lower surfaces of the feet, and at the volar surface of the forearm. The older subjects were assigned to one of four groups of 15 subjects each, depending on reported lifetime habits of physical activity and smoking: (1) active smokers, (2) active nonsmokers, (3) inactive smokers, and (4) inactive nonsmokers. Peripheral blood flow was assessed at the forefinger, foot, and forearm by means of laser-Doppler imaging and skin temperature recordings, under resting conditions and during and after a 5-min exposure to mild cooling (28 degrees C). Consistent with previous studies, tactile acuity thresholds in the foot and finger averaged about 80% higher in the older subjects than in the younger subjects, but only about 22% higher in the forearm. Although the upper surface of the fingertip was more sensitive than the lower surface in both younger and older subjects, the age-related decline in tactile acuity was nearly identical on both sides of the finger and foot. The latter finding refutes the hypothesis that the larger effect of aging in the extremities results from greater physical wear and tear on the contact surfaces of the hands and feet. Self-reported lifetime histories of physical activity and smoking were not significantly associated with measures of cutaneous blood flow or tactile thresholds. Possible reasons for this lack of association are discussed, including the inherent limitations of testing only healthy older subjects, and the concept of "successful aging".     

潍坊市2007-2012年消除麻疹策略与效果评价

目的了解潍坊市2007-2012年麻疹疫情流行规律,为消除麻疹策略提供科学依据。方法采用描述性流行病学方法,研究探讨潍坊市2007-2012年麻疹流行规律。结果2007-2012年潍坊市报告麻疹确诊病例385例,均为散发病例,无死亡病例,年均发病率为0．72／10万,其中2008、2010年出现两个发病高峰,发病率分别为1．49／10万、1．17／10万,2012年发病率降至0．033／10万。3-5月为发病高峰,病例主要集中在寿光、诸城、安丘、青州四个市,占72．73％（280／385）。发病年龄最小2个月,最大63岁,病例年龄以〈1岁婴儿和20-44岁成年人为主。职业以民工、工人、农民和散居儿童为主,民工、工人和农民所占比例平均为52．47％（202／385）;散居儿童所占比例平均为22．08％（85／385）;民工、工人、农民和散居儿童发病人群所占比例逐渐升高,托幼儿童和学生逐渐降低。≥8月龄病例中有明确麻疹疫苗免疫史者96例,占26．74％;其中8月龄～14岁有明确麻疹免疫史者66例,占该年龄组病例的66％。结论潍坊市麻疹发病年龄构成以小于1岁婴儿和20～44岁成年人为主,出现向两极移动现象,1岁以下婴幼儿发病呈上升趋势。今后要提高常规免疫接种率和及时接种率,降低小年龄儿童麻疹发病率,适时对重点地区、重点人群开展麻疹疫苗强化免疫,消除免疫空白。     

The prevalence of helicobacteriosis in regions of Siberia based on serological study data

687 adults in 5 regions of Siberia and 79 children and young persons in Novosibirsk were examined. IgG antibodies to H. pylori in their blood sera were determined with the use the enzyme immunoassay. The detection rate of antibodies among the adult population varied within 70-87%, depending on the region, being somewhat lower among the population north of latitude 60 degrees (75%) in comparison with the population residing south of this latitude (86%, p < 0.001). In Novosibirsk the number of seropositive persons was found to be unrelated to sex, age and clinical manifestations of digestive tract diseases. A high detection rate of antibodies to H. pylori was registered in persons aged 25-34 years with a minor increase in older age groups. In children the detection rate increased with age: 29% in children of 5-10 years old and 56% in children 11-14 years old. By the age of 15 more than a half of the children had antibodies.