Relationship between syncopal symptoms and head-up tilt test modes.

OBJECTIVE: Head-up tilt test (HUTT) is an important tool in the diagnosis of pediatric vasovagal syncope. This research will explore the relationship between syncopal symptoms and HUTT modes in pediatric vasovagal syncope. METHODS: A retrospective analysis was performed on the clinical data of 2513 children aged 3-18 years, who were diagnosed with vasovagal syncope, from Jan. 2001 to Dec. 2021 due to unexplained syncope or pre-syncope. The average age was 11.76 ± 2.83 years, including 1124 males and 1389 females. The patients were divided into the basic head-up tilt test (BHUT) group (596 patients) and the sublingual nitroglycerine head-up tilt test (SNHUT) group (1917 patients) according to the mode of positive HUTT at the time of confirmed pediatric vasovagal syncope. RESULTS: (1) Baseline characteristics: Age, height, weight, heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP), and composition ratio of syncope at baseline status were higher in the BHUT group than in the SNHUT group (all P < 0.05). (2) Univariate analysis: Age, height, weight, HR, SBP, DBP, and syncope were potential risk factors for BHUT positive (all P < 0.05). (3) Multivariate analysis: syncope was an independent risk factor for BHUT positive, with a probability increase of 121% compared to pre-syncope (P<0.001). CONCLUSION: The probability of BHUT positivity was significantly higher than SNHUT in pediatric vasovagal syncope with previous syncopal episodes.

Effects of the Long-Term Continuous Cropping of Yongfeng Yam on the Bacterial Community and Function in the Rhizospheric Soil.

Replant disease caused by continuous cropping commonly occurs in yam with consecutive monoculture. However, little is known about how the continuous cropping of yam affects the rhizospheric soil bacterial community structure. In this study, the effects of continuous cropping on rhizospheric soil characteristics, bacterial diversity, and community structure were investigated in the Yongfeng yam fields under monoculture for 1, 5, 10, 15, and 20 years. Long-term monoculture caused soil acidification and increased the concentration of available potassium (AK) and available phosphorus (AP), and soil bacterial richness, but decreased the soil bacterial diversity. An exception was for the field under monoculture for 20 years as it showed the highest bacterial diversity. The relative abundance of beneficial bacteria, such as Proteobacteria, Actinobacteria, and Chloroflexi decreased while the relative abundance of harmful bacteria, including Gemmatimonadetes and Acidobacteria, increased with an extended continuous cultivation time. The networks varied among yams with different cultivation years and became complex with the increase in cultivation years. However, after time in monoculture, the bacterial network decreased gradually and existed stably. These changes in bacterial community composition and co-occurrence of networks may increase the potential risk of soil-borne disease and reduce the yield and quality of Yongfeng yam.

[Differences of age and gender in orthostatichypertension-a single-center study].

OBJECTIVE: To explore the differences of Chinese people's age and gender in orthostatic hypertension (OHT) by a single-center experience study.
 METHODS: A total of 2 994 patients with unexplained syncope and dizziness, who were outpatients or had been hospitalized in Second Xiangya Hospital, Central South University from January 2000 to August 2012, were chosen and subjected to the head-up tilt table test (HUTT). Their ages ranged from 2.00 to 78.00 years old, with an average at 19.07±14.78 years old. There were 1 406 and 1 588 cases for male and female, respectively. A total of 745 patients were OHT, who were divided into a adult group (≥18 years old, 247/904 cases) and a children group (<18 years old, 498/2 090 cases). The difference of the occurrence rate, classification, and 3 min quantity of blood pressure were analyzed.
 RESULTS: 1) The incidence of OHT in HUTT was 24.88% (745/2 994 cases). There was no statistical difference between the males and the females(25.75% vs 24.12%, χ2=1.058, P>0.05), but it was higher in the adult group compared with that in the children group (27.05% vs 23.83%, χ2=4.125, P=0.042). There were 52 cases (6.98%) of high systolic and high diastolic blood pressure (sOHT merge dOHT), 16 cases (2.15%) of simple high systolic blood pressure OHT (sOHT), and 677 cases (90.87%) of simple high diastolic blood pressure OHT (dOHT) in the 745 patients with OHT. The incidence of dOHT and sOHT merge sOHT in the adults group were significantly higher than those in the children group (1.11% vs 0.29%, χ2=7.965, P<0.01; 2.88% vs 1.24%, χ2=9.849, P<0.01, respectively); there was no statistical difference in simple dOHT between males and females (23.56% vs 22.20%, χ2=0.668, P>0.05); there was also no statistical difference in sOHT plus dOHT and dOHT between males and females (sOHT merge dOHT: 1.71% vs 1.76%, χ2=0.014, P>0.05; dOHT: 23.68% vs 21.66%, χ2=1.742, P>0.05; 1.71% vs 1.76%, χ2=0.014, P>0.05, respectively); but the dOHT was significantly higher in the males than that in the females in the children group (24.53% vs 19.74%, χ2=6.933, P>0.05). 2) There was no difference in the increment of systolic blood pressure in sOHT plus dOHT [(25.62±4.96) mmHg vs (23.54±5.83) mmHg, t=1.385, P>0.05] and the increment of diastolic blood pressure in dOHT [(13.46±3.49) mmHg vs (13.23±3.22) mmHg, t=0.840, P>0.05] between the adults group and the children group. There was no difference in the increment of systolic blood pressure in sOHT [(25.44±4.96) mmHg vs (23.68±5.35) mmHg, t=1.411, P>0.05] and the increment of diastolic blood pressure in dOHT [(14.09±4.28) mmHg vs (13.05±3.82) mmHg, t=1.887, P>0.05] between the adults group and the children group.
 CONCLUSION: The incidence of OHT is higher in the adults group than that in the children group. There is no difference in systolic and diastolic blood pressure increment within 3 minutes during HUTT between the adults and children.

[Clinical significance of changes in T wave and ST segment amplitudes on electrocardiogram from supine to standing position among children with unexplained chest tightness or pain in resting stage].

OBJECTIVE: To investigate the clinical significance of changes in T wave and ST segment amplitudes on electrocardiogram (ECG) from supine to standing position in children with unexplained chest tightness or pain in resting stage. METHODS: A total of 122 6-14-year-old children with a chief complaint of unexplained chest tightness or pain (resting stage) underwent head-up tilt test (HUTT). According to HUTT results, these children were divided into HUTT-positive (n=61) and HUTT-negative groups (n=61). They underwent 12-lead ECG in the supine and standing positions, and heart rate and T wave and ST segment amplitudes in II, III, aVF and V5 leads were measured. RESULTS: In the HUTT-negative group, heart rates were significantly higher in the standing position than in the supine position (P<0.05), T wave amplitudes in II, III, aVF, and V5 leads were significantly lower in the standing position than in the supine position (P<0.05), and ST segment amplitudes in II, aVF and V5 leads were significantly higher in the standing position than in the supine position (P<0.05). In the HUTT-positive group, heart rates were significantly higher in the standing position than in the supine position (P<0.05), T wave amplitudes in II, III, aVF and V5 leads were significantly lower in the standing position than in the supine position (P<0.05), and ST segment amplitude in V5 lead was significantly higher in the standing position than in the supine position (P<0.05). There were no significant differences between the two groups with respect to ST segment amplitude and T wave amplitude in II, III and aVF leads of the supine or standing position (P>0.05). Compared with the HUTT-negative group, the HUTT-positive group had significantly greater T wave amplitude differences in II, III, aVF and V5 leads, and heart rate difference from supine to standing position (P<0.05). CONCLUSIONS: Among the children with unexplained chest tightness or pain in resting stage, T wave amplitude differences in II, III, aVF and V5 leads and heart rate difference from supine to standing position are greater in the HUTT-positive group than in the HUTT-negative group. This suggests that the changes in T wave amplitude on ECG from supine to standing position can indicate autonomic nervous system dysfunction.

[Investigation of 24-hour blood pressure monitoring for evaluating treatment outcome of nerve-mediated syncope in children].

OBJECTIVE: To investigate the clinical significance of 24-hour blood pressure monitoring (ABPM) for evaluating the treatment outcome of nerve-mediated syncope (NMS) in children. METHODS: Twenty-eight children with NMS confirmed by a head-up tilt table test (HUTT) (12 males and 16 females, aged 6-13 years) and with a chief complaint of unexplained syncope or pre-syncope between February 2010 and August 2012, were included in the study. These children received health education combined with therapy using oral rehydration salts solution and were then reexamined for clinical symptoms as well as HUTT and ABPM results. RESULTS: Of 28 NMS cases, 22 were vasodepressive type, 5 were mixed type, and 1 was cardioinhibitory type. The follow-up showed that 27 (96%) of all cases had improved clinical symptoms, and 18 (64%) had improved HUTT results. The ABPM follow-up revealed no significant changes in 24-hour mean systolic pressure, 24-hour mean diastolic pressure, daytime mean systolic pressure, daytime mean diastolic pressure, nighttime mean systolic pressure, nighttime mean diastolic pressure, day-night difference of systolic pressure, and day-night difference of diastolic pressure after treatment (P>0.05). The percentage of children with a dipper blood pressure pattern increased from 29% (8/28) before treatment to 50% (14/28) after treatment; the percentage of children with a non-dipper blood pressure pattern decreased from 71% (20/28) before treatment to 50% (14/28) after treatment. CONCLUSIONS: As an effective, objective and non-invasive monitoring means, ABPM is of some clinical significance for evaluating the treatment outcome of NMS in children.

Uric acid spherulites in the reflector layer of firefly light organ.

BACKGROUND: In firefly light organs, reflector layer is a specialized tissue which is believed to play a key role for increasing the bioluminescence intensity through reflection. However, the nature of this unique tissue remains elusive. In this report, we investigated the role, fine structure and nature of the reflector layer in the light organ of adult Luciola cerata. PRINCIPAL FINDINGS: Our results indicated that the reflector layer is capable of reflecting bioluminescence, and contains abundant uric acid. Electron microscopy (EM) demonstrated that the cytosol of the reflector layer's cells is filled with densely packed spherical granules, which should be the uric acid granules. These granules are highly regular in size (∼700 nm in diameter), and exhibit a radial internal structure. X-ray diffraction (XRD) analyses revealed that an intense single peak pattern with a d-spacing value of 0.320 nm is specifically detected in the light organ, and is highly similar to the diffraction peak pattern and d-spacing value of needle-formed crystals of monosodium urate monohydrate. However, the molar ratio evaluation of uric acid to various cations (K(+), Na(+), Ca(2+) and Mg(2+)) in the light organ deduced that only a few uric acid molecules were in the form of urate salts. Thus, non-salt uric acid should be the source of the diffraction signal detected in the light organ. CONCLUSIONS: In the light organ, the intense single peak diffraction signal might come from a unique needle-like uric acid form, which is different from other known structures of non-salt uric acid form. The finding of a radial structure in the granules of reflector layer implies that the spherical uric acid granules might be formed by the radial arrangement of needle-formed packing matter.

[Causes of unexplained syncope in children].

OBJECTIVE: To investigate the common causes of unexplained syncope in children. METHODS: A total of 434 children with unexplained syncope who were aged from 3.0 to 17.9 years (192 males and 242 females) and who saw the doctor between January 2006 and October 2011. were examined in order to explore the detailed histories and causes of syncope and to analyze variance in causes among different ages, genders, syncope frequencies and head-up tilt test (HUTT) results. RESULTS: (1) The causes of occasional syncope included persistent standing (30%), movement (13%), change in body position(9%), sitting(7%), and playing(6%). Persistent standing was more common as a cause in females than in males (P<0.01). Micturition syncope was mainly seen in males. Sultry weather was the main cause of syncope in females. Change in body position was a more common cause in the ≥12 years group than in the <12 years group (P<0.05), while other causes showed no significant differences among different age groups. Change in body position was a more common cause of syncope in children with negative HUTT results than in those with positive HUTT results (P<0.05). (2) All causes of occasional syncope can induce repeated syncope, and most repeated syncope (56%) had the same cause. CONCLUSIONS: The common causes of unexplained syncope include persistent standing, movement and changes of body position in children. Avoiding these causes is helpful for prevention of childhood syncope.

[Diagnosis of vasovagal syncope in children with postural orthostatic tachycardia syndrome].

OBJECTIVE: To study the diagnosis of vasovagal syncope (VVS) in children with postural orthostatic tachycardia syndrome (POTS). METHODS: The clinical data of 57 children with POTS diagnosed by the head-up tilt test between January 2007 and December 2010 were studied retrospectively. Of the 57 children, there were 29 boys and 28 girls who were aged from 5 to 16 years (12.2±1.9 years). RESULTS: Twenty-four (42%) out of 57 children were diagnosed with VVS by prolonging the duration of the head-up tilt test (for the children with orthostatic tolerance): cardioinhibitory (20 cases), mixed (3 cases) and vasoinhibitory (1 case). The POTS children with VVS were older than those without (13.0±1.4 years vs 11.5±2.1 years; P<0.05). There were no significant differences in gender and clinical symptoms between the POTS children with and without VVS. CONCLUSIONS: Some children with POTS may have coexisting VVS, suggesting that it is important to avoid misdiagnosis of VVS by prolonging the duration of head-up tilt test in POTS children with orthostatic tolerance. There are no obvious differences in gender and clinical symptoms between the POTS children with and without VVS.

Relationship between pitch value or S/D ratio of torsion of cord and fetal outcome.

OBJECTIVE: To evaluate whether applying pitch values at different positions of the umbilical cord or the umbilical artery blood flow systolic/diastolic (S/D) ratio measured by color ultrasound could forecast excessive torsion of cord and help in selection of the appropriate mode of delivery. METHODS: This study included 184 pregnant women between 37 and 41 weeks of gestation and their neonates. We analyzed the umbilical cord's spiral distance, and the umbilical artery blood flow parameters at the cord's initial section, middle section and the section into the placenta. We also examined the fetal umbilical cord after birth, performed blood gas analysis of umbilical cord blood and recorded the neonatal Apgar score. RESULTS: Excessive torsion of cord diagnosed by ultrasound and in postnatal anatomy had the same rate of 91%. With lower pitch values (<2.0) and higher S/D ratios (>3.0), the possibility of fetal distress was increased, the neonatal Apgar score was decreased and umbilical blood pH values < 7.2 were more common. CONCLUSION: Pitch values and blood flow S/D ratios in different sections of the umbilical cord measured by color ultrasound could forecast excessive torsion of cord and have great significance in reducing the perinatal death rate caused by umbilical cord factors.