Neonatal GABAergic transmission primes vestibular gating of output for adult spatial navigation

GABAergic interneurons are poised with the capacity to shape circuit output via inhibitory gating. How early in the development of medial vestibular nucleus (MVN) are GABAergic neurons recruited for feedforward shaping of outputs to higher centers for spatial navigation? The role of early GABAergic transmission in assembling vestibular circuits for spatial navigation was explored by neonatal perturbation. Immunohistochemistry and confocal imaging were utilized to reveal the expression of parvalbumin (PV)-expressing MVN neurons and their perineuronal nets. Whole-cell patch-clamp recording, coupled with optogenetics, was conducted in vitro to examine the synaptic function of MVN circuitry. Chemogenetic targeting strategy was also employed in vivo to manipulate neuronal activity during navigational tests. We found in rats a neonatal critical period before postnatal day (P) 8 in which competitive antagonization of GABAergic transmission in the MVN retarded maturation of inhibitory neurotransmission, as evidenced by deranged developmental trajectory for excitation/inhibition ratio and an extended period of critical period-like plasticity in GABAergic transmission. Despite increased number of PV-expressing GABAergic interneurons in the MVN, optogenetic-coupled patch-clamp recording indicated null-recruitment of these neurons in tuning outputs along the ascending vestibular pathway. Such perturbation not only offset output dynamics of ascending MVN output neurons, but was further accompanied by impaired vestibular-dependent navigation in adulthood. The same perturbations were however non-consequential when applied after P8. Results highlight neonatal GABAergic transmission as key to establishing feedforward output dynamics to higher brain centers for spatial cognition and navigation.

Virtual reality: a technology to promote active learning of physiology for students across multiple disciplines

The usefulness of virtual reality (VR) technology in physiology education is largely unexplored. Although VR has the potential to enrich learning experience by enhancing the spatial awareness of students, it is unclear whether VR contributes to active learning of physiology. In the present study, we used a mixed-method research approach to investigate students' perceptions of physiology learning based on VR simulations. Quantitative and qualitative data indicate that the implementation of VR learning environments improves the quality of physiology education by promoting active learning in terms of interactive engagement, interest, problem-solving skills, and feedback. In the Technology-Enabled Active Learning Inventory, which consisted of 20 questions to which students responded along a 7-point Likert scale, the majority of students agreed that VR learning of physiology not only stimulated their curiosity (77%; P < 0.001) but also allowed them to obtain knowledge through diverse formats (76%; P < 0.001), participate in thought-provoking dialogue (72%; P < 0.001), and interact better with peers (72%; P < 0.001). Positive responses in the social, cognitive, behavioral, and evaluative domains of active learning were received from students across different disciplines, including medicine, Chinese medicine, biomedical sciences, and biomedical engineering. Their written feedback showed that VR enhanced their interest in physiology and facilitated the visualization of physiological processes to improve their learning. Overall, this study supports that the integration of VR technology into physiology courses can be an effective teaching strategy.NEW & NOTEWORTHY Virtual reality (VR) improves physiology education by promoting active learning in terms of interactive engagement, interest, problem-solving skills, and feedback. Positive responses toward multiple components of active learning were received from students across different disciplines. The majority of students agreed that VR learning of physiology not only stimulated their curiosity but also allowed them to obtain knowledge through diverse formats, participate in thought-provoking dialogue, and interact better with peers.

Timely insertion of AMPA receptor in developing vestibular circuits is required for manifestation of righting reflexes and effective navigation

Vestibular information processed first by the brainstem vestibular nucleus (VN), and further by cerebellum and thalamus, underlies diverse brain function. These include the righting reflexes and spatial cognitive behaviour. While the cerebellar and thalamic circuits that decode vestibular information are known, the importance of VN neurons and the temporal requirements for their maturation that allow developmental consolidation of the aforementioned circuits remains unclear. We show that timely unsilencing of glutamatergic circuits in the VN by NMDA receptor-mediated insertion of AMPAR receptor type 1 (GluA1) subunits is critical for maturation of VN and successful consolidation of higher circuits that process vestibular information. Delayed unsilencing of NMDA receptor-only synapses of neonatal VN neurons permanently decreased their functional connectivity with inferior olive circuits. This was accompanied by delayed pruning of the inferior olive inputs to Purkinje cells and permanent reduction in their plasticity. These derangements led to deficits in associated vestibular righting reflexes and motor co-ordination during voluntary movement. Vestibular-dependent recruitment of thalamic neurons was similarly reduced, resulting in permanently decreased efficiency of spatial navigation. The findings thus show that well-choreographed maturation of the nascent vestibular circuitry is prerequisite for functional integration of vestibular signals into ascending pathways for diverse vestibular-related behaviours.

[Correlation between nUGT1A1 gene polymorphisms and adverse events of irinotecan plus S-1 for patients with recurrent or metastatic esophageal squamous cell carcinoma: a prospective, open-label, randomized controlled trial (ESWN 01)]

Objective: To investigate the correlation between UGT1A1 polymorphisms and the irinotecan plus S-1 regimen-induced toxicities in Chinese advanced esophageal squamous cell carcinoma (ESCC) patients. Methods: A total of 46 recurrent or metastatic ESCC patients selected from ESWN 01 trial were randomly assigned to irinotecan plus S-1 group [intravenous infusion of irinotecan (160 mg/m(2)) on day 1 and oral S-1 (80-120 mg) on days 1-10, repeated every 14 days]. Peripheral venous blood at baseline was collected and genomic DNA was extracted. The genetic polymorphisms of UGT1A1*6 and UGT1A1*28 were analyzed by polymerase chain reaction (PCR) amplification. Irinotecan plus S-1 regimen-induced toxicities of patients with different UGT1A1 polymorphisms were observed. The correlation between UGT1A1 polymorphisms and the adverse effects was analyzed. Results: Among the 46 patients, the numbers of UGT1A1*6 wild type genotype (GG), mutant heterozygote (GA) and mutant homozygote (AA) were 30, 15 and 1, while those with UGT1A1*28 wild type genotype (TA6/6), mutant heterozygote (TA6/7) and mutant homozygote (TA7/7) were 36, 8 and 2, respectively. Only one patient with UGT1A1*6 AA genotype occurred grade 3 diarrhea, while one of the 2 patients with UGT1A1*28 TA7/7 genotype occurred grade 4 diarrhea. No neutropenia was observed in the patient with UGT1A1*6 AA genotype, however, both of the two patients with UGT1A1*28 TA7/7 genotype occurred grade 3-4 neutropenia. Patients with UGT1A1*28 genetic polymorphism (TA 6/7 or TA7/7) had a higher response rate compared with wild-type TA6/6 carriers. (55.6% versus 26.5%). Conclusions: The homozygous genotype of UGT1A1*6 AA and UGT1A1*28 TA7/7 are rare (<5%) in Chinese ESCC population. Not all homozygous AA and TA7/7 carriers occur severe dose limited toxicities (DLT) when treated with irinotecan (160 mg/m(2)) plus S-1 regimen for 2 weeks. However, it's still necessary torigorously observe the occurrence of severe diarrhea and neutropenia in patients with UGT1A1*6 AA and UGT1A1*28 TA7/7 and adjust the dose timely.

Vision on the internationalization of physiology education: Trends and prospects

Rapid advancement of physiology education has occurred since the twentieth century due to the emergence of new pedagogies and collaborative effort of physiologists worldwide. Physiological organizations and institutions contribute to the teaching of physiology through international congresses, education symposia, teaching workshops, exchange programs, and journal publications. The Internet and information technologies play a crucial role in the promotion and improvement of computer-based physiology education across different countries. Interactive teaching practices and problem-based learning have also become globally applied strategies to enhance students' motivation and facilitate learning effectiveness. In this article, we review the global development and implementation of pedagogical approaches to the teaching of physiology, as well as the emerging trends and practices for physiology education in the future.

[Association of abdominal obesity and obesity types with carotid intima-media thickness in children in China]

Objective: To evaluate the association of abdominal obesity and obesity types with carotid intima-media thickness (cIMT) in children and provide scientific evidence for the prevention of abnormal vascular structure. Methods: Based on the "Children's Cardiovascular Health Cohort" conducted in Huantai county of Zibo, Shandong province from November 2017 to January 2018, a total of 1 240 children, including 657 boys (53.0%), who had completed data of sex, age, physical examinations, blood biochemical indices and lifestyle variables (collected by questionnaires) were included for the analysis. Covariance analysis was used to compare the levels of cIMT in groups with normal waist circumference, pre-abdominal obesity and abdominal obesity. Logistic regression analysis was used to evaluate the association of pre-abdominal obesity and abdominal obesity with high cIMT, and the association of combined effect of general overweight or obesity and abdominal obesity or pre-abdominal obesity with high cIMT. Results: The levels of cIMT in children with pre-abdominal obesity (0.47±0.03) mm and abdominal obesity (0.50±0.04) mm were higher than that in children with normal waist circumference (0.45±0.05) mm, the difference was significant (P<0.001). The detection rates of high cIMT in children with pre-abdominal obesity(20.8%) and abdominal obesity (49.5%) were higher than that in children with normal waist circumference (8.8%), the difference was significant (P<0.001). Compared with normal waist circumference, pre-abdominal obesity and abdominal obesity were significantly associated with high cIMT (pre-abdominal obesity: OR=2.53, 95%CI: 1.67-3.84; abdominal obesity: OR=8.56, 95%CI: 5.97-12.29) after adjustment for potential covariates. Compared with normal body mass index and normal waist circumference, abdominal obesity or pre-abdominal obesity alone (OR=2.24, 95%CI: 1.36-3.69), and mixed overweight and obesity (OR=6.94, 95%CI: 4.87-9.90) were significantly associated with high cIMT. Conclusions: The association between abdominal obesity and high cIMT was significant in children, and the association was stronger between mixed overweight or obesity and high cIMT, suggesting that we should consider mixed overweight and obesity in the prevention of abnormal vascular structure.

[Detection of hypertension based on measurements at three occasions in different days and its relationship with obesity in children]

Objective: To analyze the trends in blood pressure (BP) values and the elevated BP based on the measurements at three occasions in different days and its relationship with obesity in children and provide scientific evidence for the identification and prevention of hypertension in children. Methods: A public primary school in Huantai county of Zibo, Shandong province, was selected as the investigation field by using a convenient cluster sampling method. The baseline survey of "Children's Cardiovascular Health Cohort" was carried out from November 2017 to January 2018. All the students with willingness and informed consent in this school were included in the survey, and the valid sample size was 1 505 children (aged 6-11 years). Children with elevated BP at the measurement of the first occasion should had a second measurement 2 weeks later, and a third measurement was given 2 weeks later if BP was still high at the measurement of the second occasion. Hypertension was confirmed if elevated BP was detected in the measurements at all the three occasions in different days. Multivariate linear regression model was used to assess the trend in BP values in children in the measurements at three occasions in different days, Cochran-Armitage trend analysis was used to evaluate the trend of elevated BP, and logistic regression model was used to analyze the relationship of elevated BP with obesity at three occasions in different days. Results: In this study, with the increase of follow-up visits, the BP levels continued to rise (trend P<0.05). The elevated BP rates at three occasions were 15.5%, 4.0% and 1.9%, respectively, showing a significantly downward trend (trend P<0.05). Compared with both normal weight and normal waist circumference, the association between obesity types (general obesity only, abdominal obesity only, and mixed obesity) and elevated BP at three occasions increased (the first occasion: OR=3.62, 95%CI: 2.65-4.96; the second occasion: OR=9.50, 95%CI: 4.95-18.22; and the third occasion: OR=8.94, 95%CI: 3.48-22.96; all P<0.05). Stratified analysis by gender showed similar results. Conclusions: The elevated BP rates based on the measurements at three occasions in different days in children aged 6-11 years showed a significant decrease trend. The association between different types of obesity (especially mixed obesity) and elevated BP in children became stronger gradually with the progress of the follow up.

Regulatory roles of perineuronal nets and semaphorin 3A in the postnatal maturation of the central vestibular circuitry for graviceptive reflex

Perineuronal nets (PN) restrict neuronal plasticity in the adult brain. We hypothesize that activity-dependent consolidation of PN is required for functional maturation of behavioral circuits. Using the postnatal maturation of brainstem vestibular nucleus (VN) circuits as a model system, we report a neonatal period in which consolidation of central vestibular circuitry for graviception is accompanied by activity-dependent consolidation of chondroitin sulfate (CS)-rich PN around GABAergic neurons in the VN. Postnatal onset of negative geotaxis was used as an indicator for functional maturation of vestibular circuits. Rats display negative geotaxis from postnatal day (P) 9, coinciding with the condensation of CS-rich PN around GABAergic interneurons in the VN. Delaying PN formation, by removal of primordial CS moieties on VN with chondroitinase ABC (ChABC) treatment at P6, postponed emergence of negative geotaxis to P13. Similar postponement was observed following inhibition of GABAergic transmission with bicuculline, in line with the reported role of PN in increasing excitability of parvalbumin neurons. We further reasoned that PN-CS restricts bioavailability of plasticity-inducing factors such as semaphorin 3A (Sema3A) to bring about circuit maturation. Treatment of VN explants with ChABC to liberate PN-bound Sema3A resulted in dendritic growth and arborization, implicating structural plasticity that delays synapse formation. Evidence is thus provided for the role of PN-CS-Sema3A in regulating structural and circuit plasticity at VN interneurons with impacts on the development of graviceptive postural control.

Development of neural correlates of linear motion in the rat vestibular nucleus

The capability of the central vestibular system in utilizing cues arising from the inner ear determines the ability of animals to acquire the sense of head orientations in the three-dimensional space and to shape postural movements. During development, neurons in the vestibular nucleus (VN) show significant changes in their electrophysiological properties. An age-dependent enhancement of membrane excitability is accompanied by a progressive increase in firing rate and discharge regularity. The coding of horizontal and vertical linear motions also exhibits developmental refinement in VN neurons. Further, modification of cell surface receptors, such as glutamate receptors, of developing VN neurons are well-orchestrated in the course of maturation, thereby regulating synaptic efficacy and spatial coding capacity of these neurons in local circuits. Taken together, these characteristic features of VN neurons contribute to developmental establishment of space-centered coordinates within the brain.

Maturation profile of inferior olivary neurons expressing ionotropic glutamate receptors in rats: role in coding linear accelerations

Using sinusoidal oscillations of linear acceleration along both the horizontal and vertical planes to stimulate otolith organs in the inner ear, we charted the postnatal time at which responsive neurons in the rat inferior olive (IO) first showed Fos expression, an indicator of neuronal recruitment into the otolith circuit. Neurons in subnucleus dorsomedial cell column (DMCC) were activated by vertical stimulation as early as P9 and by horizontal (interaural) stimulation as early as P11. By P13, neurons in the β subnucleus of IO (IOβ) became responsive to horizontal stimulation along the interaural and antero-posterior directions. By P21, neurons in the rostral IOβ became also responsive to vertical stimulation, but those in the caudal IOβ remained responsive only to horizontal stimulation. Nearly all functionally activated neurons in DMCC and IOβ were immunopositive for the NR1 subunit of the NMDA receptor and the GluR2/3 subunit of the AMPA receptor. In situ hybridization studies further indicated abundant mRNA signals of the glutamate receptor subunits by the end of the second postnatal week. This is reinforced by whole-cell patch-clamp data in which glutamate receptor-mediated miniature excitatory postsynaptic currents of rostral IOβ neurons showed postnatal increase in amplitude, reaching the adult level by P14. Further, these neurons exhibited subthreshold oscillations in membrane potential as from P14. Taken together, our results support that ionotropic glutamate receptors in the IO enable postnatal coding of gravity-related information and that the rostral IOβ is the only IO subnucleus that encodes spatial orientations in 3-D.

Postnatal expression of TrkB receptor in rat vestibular nuclear neurons responsive to horizontal and vertical linear accelerations

We examined the maturation expression profile of tyrosine kinase B (TrkB) receptor in rat vestibular nuclear neurons that were activated by sinusoidal linear acceleration along the horizontal or vertical axis. The otolithic origin of Fos expression in these neurons was confirmed with labyrinthectomized controls and normal controls, which showed only sporadically scattered Fos-labeled neurons in the vestibular nucleus. In P4-6 test rats, no Fos-labeled neurons were found in the vestibular nucleus, but the medial and spinal vestibular neurons showed weak immunoreactivity for TrkB. The intensity of TrkB immunoreactivity in vestibular nuclear neurons progressively increased in the second postnatal week but remained low in adults. From P7 onward, TrkB-expressing neurons responded to horizontal or vertical otolithic stimulation with Fos expression. The number of Fos-labeled vestibular nuclear neurons expressing TrkB increased with age, from 13-43% in P7 rats to 85-90% in adult rats. Our results therefore suggest that TrkB/neurotrophin signaling plays a dominant role in modulating vestibular nuclear neurons for the coding of gravity-related horizontal head movements and for the regulation of vestibular-related behavior during postnatal development.

Effects of diet, packaging, and irradiation on protein oxidation, lipid oxidation, and color of raw broiler thigh meat during refrigerated storage

This study was designed to evaluate the effects of dietary treatment, packaging, and irradiation singly or in combination on the oxidative stability of broiler chicken thigh meat. A total of 120 four-week-old chickens were divided into 12 pens (10 birds/pen), and 4 pens of broilers were randomly assigned to a control oxidized diet (5% oxidized oil) or an antioxidant-added diet [500 IU of vitamin E + 200 mg/kg of butylated hydroxyanisole (BHA)] and fed for 2 wk. After slaughter, thigh meats were separated, ground, packaged in either oxygen-permeable or oxygen-impermeable vacuum bags, and irradiated at 0 or 3 kGy. Lipid oxidation (TBA-reactive substances), protein oxidation (carbonyl), and color of the meat were measured at 1, 4, and 7 d of refrigerated storage. The lipid and protein oxidation of thigh meats from birds fed the diet supplemented with antioxidants (vitamin E + BHA) was significantly lower than the lipid and protein oxidation of birds fed the control diet, whereas the lipid and protein oxidation of broilers fed the oxidized oil diet was higher than that of birds fed the control diet. Vacuum packaging slowed, but irradiation accelerated, the lipid and protein oxidation of thigh meat during storage. Dietary antioxidants (vitamin E + BHA) and irradiation treatments showed a stronger effect on lipid oxidation than on protein oxidation. A significant correlation between lipid and protein oxidation in meat was found during storage. Dietary supplementation of vitamin E + BHA and the irradiation treatment increased the lightness and redness of thigh meat, respectively. It is suggested that appropriate use of dietary antioxidants in combination with packaging could be effective in minimizing oxidative changes in irradiated raw chicken thigh meat.

[Neuronal plasticity of otolith-related vestibular system]

This review focuses on our effort in addressing the development and lesion-induced plasticity of the gravity sensing system. After severance of sensory input from one inner ear, there is a bilateral imbalance in response dynamics and spatial coding behavior between neuronal subpopulations on the two sides. These data provide the basis for deranged spatial coding and motor deficits accompanying unilateral labyrinthectomy. Recent studies have also confirmed that both glutamate receptors and neurotrophin receptors within the bilateral vestibular nuclei are implicated in the plasticity during vestibular compensation and development. Changes in plasticity not only provide insight into the formation of a spatial map and recovery of vestibular function but also on the design of drugs for therapeutic strategies applicable to infants or vestibular disorders such as vertigo and dizziness.

Correlation between adiponectin polymorphisms and non-alcoholic fatty liver disease with or without metabolic syndrome in Chinese population

BACKGROUND

To investigate the effect of single nucleotide polymorphisms (SNP) 45 and 276 of the adiponectin gene on non-alcoholic fatty liver disease (NAFLD) with or without metabolic syndrome.

METHODS

A total of 165 NAFLD, 83 NAFLD with metabolic syndrome and 160 healthy controls from Chinese population were genotyped for the adiponectin gene (+45T>G and +276G>T) by PCR-restriction fragment length polymorphism methods. Plasma adiponectin and insulin levels were determined by enzyme-linked immunosorbent assay and radioimmunoassay, respectively. Insulin resistance (IR) was evaluated by using homeostasis model assessment of IR (HOMA-IR).

RESULTS

NAFLD with metabolic syndrome had further extent of IR and hypoadiponectinemia. No association of SNP45 or SNP276 was found in NAFLD or NAFLD with metabolic syndrome. Subjects carrying the G allele of SNP45 showed higher levels of triglyceride (TG), fasting blood sugar (FBS), HOMA, body mass index (BMI), and alanine transaminase (ALT), as well as lower plasma adiponectin levels. In the normal-weight group of SNP276, subjects carrying the G allele showed higher HOMA and subjects carrying the T allele showed lower BMI.

CONCLUSIONS

Our study observed further hypoadiponectinemia and IR in NAFLD with metabolic syndrome. The T45G and G276T of the adiponectin gene may not be the important determinants of NAFLD in Chinese people, but some of them still influence serum ALT, BMI, IR, lipid, glucose metabolism and plasma adiponectin concentration.

Linear relation on the correlation in complex networks

Correlation in complex networks follows a linear relation between the degree of a node and the total degrees of its neighbors for six different classes of real networks. This general linear relation is an extension of the Aboav-Weaire law in two-dimensional cellular structures and provides a simple and different perspective on the correlation in complex networks, which is complementary to an existing description using Pearson correlation coefficients and a power law fit. Analytical expression for this linear relation for three standard models of complex networks: the Erdos-Renyi, Watts-Strogatz, and Barabasi-Albert networks is provided. The slope and intercept of this linear relation are described by a single parameter a together with the first and second moment of the degree distribution of the network. The assortivity of the network can be related to the sign of the intercept.

Trends in the prevalence of peptic ulcer disease and Helicobacter pylori infection in family physician-referred uninvestigated dyspeptic patients in Hong Kong

BACKGROUND

Peptic ulcer disease is mainly caused by Helicobacter pylori infection and the use of non-steroidal anti-inflammatory drugs.

AIM

To investigate the trends in the prevalence of peptic ulcer disease, H. pylori infection and non-steroidal anti-inflammatory drug use in uninvestigated dyspeptic patients over recent years in Hong Kong.

METHODS

Data from consecutive patients with uninvestigated dyspeptic symptoms referred by family physicians for open access upper endoscopy during 1997 and 2003 were analysed in relation to peptic ulcer disease, H. pylori infection and non-steroidal anti-inflammatory drug use.

RESULTS

Among 2700 patients included, 405 (15%) had peptic ulcer disease and 14 (0.5%) had gastric cancer. There was a reduced trend from 1997 to 2003 in the prevalence of peptic ulcer disease (17, 20, 14, 16, 13, 14 and 14%, respectively, chi2 = 5.80, P = 0.016) (mainly because of decrease in duodenal ulcers), H. pylori infection (44, 50, 49, 44, 40, 40, 36 and 43%, respectively, chi2 = 13.55, P < 0.001) and non-steroidal anti-inflammatory drug use (13, 5, 5, 6, 3, 4, 4 and 5% respectively, chi2 = 13.61, P < 0.001). The prevalence of peptic ulcer disease, H. pylori infection and non-steroidal anti-inflammatory drug use between 2001 and 2003 were significantly lower than that between 1997 and 2000 (17% vs. 13%, OR = 0.78, 95% CI: 0.63-0.96, P = 0.020 for peptic ulcer disease; 47% vs. 39%, OR =0.72, 95% CI: 0.60-0.86, P < 0.001 for H. pylori infection; and 6% vs. 4%, OR = 0.56, 95% CI: 0.39-0.82, P = 0.002 for non-steroidal anti-inflammatory drug use). H. pylori infection was associated with both duodenal ulcer (OR = 15.87, 95% CI: 10.60-23.76, P < 0.001) and gastric ulcer (OR = 3.12, 95% CI: 2.15-4.53, P < 0.001) whereas non-steroidal anti-inflammatory drug use was only associated with gastric ulcer (OR = 2.97, 95% CI: 1.70-5.20, P < 0.001).

CONCLUSIONS

The prevalence of peptic ulcer disease, mainly duodenal ulcers, was reduced in association with a decreasing trend in the prevalence of H. pylori infection and non-steroidal anti-inflammatory drug use from 1997 to 2003.

Visual performance on detection tasks with double-targets of the same and different difficulty

This paper reports a study of measurement of horizontal visual sensitivity limits for 16 subjects in single-target and double-targets detection tasks. Two phases of tests were conducted in the double-targets task; targets of the same difficulty were tested in phase one while targets of different difficulty were tested in phase two. The range of sensitivity for the double-targets test was found to be smaller than that for single-target in both the same and different target difficulty cases. The presence of another target was found to affect performance to a marked degree. Interference effect of the difficult target on detection of the easy one was greater than that of the easy one on the detection of the difficult one. Performance decrement was noted when correct percentage detection was plotted against eccentricity of target in both the single-target and double-targets tests. Nevertheless, the non-significant correlation found between the performance for the two tasks demonstrated that it was impossible to predict quantitatively ability for detection of double targets from the data for single targets. This indicated probable problems in generalizing data for single target visual lobes to those for multiple targets. Also lobe area values obtained from measurements using a single-target task cannot be applied in a mathematical model for situations with multiple occurrences of targets.

Photodegradation mechanism and rate improvement of chlorinated aromatic dye in non-ionic surfactant solutions

A typical insoluble chlorinated aromatic dye (CAD), disperse red (DR), was used to explore the reaction mechanism and kinetics of photodegradation in non-ionic surfactant solutions. The use of an additional hydrogen source and photosensitizer is also studied to improve the decay rates. The decay rate of dye in surfactants depends on the Km of surfactants and their ability to offering an effective hydrogen source. The photodegradation of CAD can be divided into three stages: the initial lag stage. the fast degradation stage and the final retardation stage. The lag stage will vanish and the decay rates of dye can be greatly improved by 2.5-3.6 times after adding an additional hydrogen source (NaBH4) or photosensitizer (acetone) to the surfactant micellar solution. However, the use of an additional hydrogen source or photosensitizer has dosage limitations in such applications. The photoreduction of DR is the main reaction mechanism, in which photodechlorination is observed first with the generation of HCI as the final product, then followed by photodecolorization by breaking the azo bond of the chromophore.

[Inhibition of parvovirus H-1 on transplantable human hepatoma and its histological and histobiochemical studies]

A transplantable human hepatoma model, the QGY-9204, was used in this study. The growth kinetics of hepatoma in nude mice were compared after injection of parvovirus H-1 into the tumor growth. Significant difference in growth curves were seen between injected groups with H-1 dosages of 5 x 10(7) PFU and 5 x 10(8) PFU and that of control. It indicated that parvovirus H-1 was capable of suppressing the growth of human hepatoma. Previous studies showed H-1 is oncotropic, oncosuppressive and oncolytic. For histological, ultrastructural and histochemical examinations, transplantable hepatomas were taken at different time interval post H-1 (1 x 10(8) PFU per tumor growth) injection. For H-1 DNA amplification and H-1 nonstructural protein expression, PCR and ABC approach in hepatoma paraffin sections were used. The H-1 treated groups exhibited obvious signs of necrosis. It started on 3rd day post infection (3 d.p.i.) and the area of necrosis enlarged consecutively on 7 d.p.i., 10 d.p.i. and 14 d.p.i., but none was seen in saline-injected group even on 14 d.p.i. H-1 virions were also detected in the damaged tumor cells with numerous vacuoles in cytoplasm. Specific band (908 bp) of H-1 DNA and ABC immunostaining indicated H-1 DNA replication and NS-1 expression in tumors of treated groups, their time course was well in accordance with that process of necrosis. These results suggest that parvovirus H-1 promotes tumor necrosis by its DNA replication and cytotoxic NS-1 protein expression, and thus, it inhibits hepatoma growth and induces oncosuppression and oncolysis.

Two new rat alpha-globin sequences as identified by the conserved region PCR

Based on the notion that regions of structural genes which encode critical domains of the corresponding proteins are highly conserved among closely related species, oligonucleotide primers were designed and used to amplify the alpha-globin sequence(s) of the Sprague-Dawley (SD) rat. Data of these amplified sequence constructs showed that two new rat alpha-globin specific sequences have been identified. Southern hybridization confirmed the presence of these sequences in the rat genome.

The relationship of serum vitamin A, cholesterol, and triglycerides to the incidence of ovarian cancer

Prospective and retrospective studies have suggested that serum vitamin A and total cholesterol levels may be associated with cancer. Our study showed that the mean (+/- SEM) concentrations of serum vitamin A 489 +/- 33.28 (mean +/- SEM micrograms/liter and serum total cholesterol 174.7 +/- 8.96 (mean +/- SEM) mg/dl from ovarian cancer patients in Singapore were significantly lower than the respective values of 668 +/- 25.10 (mean +/- SEM) microgram/liter and 210.7 4.48 (mean +/- SEM) mg/dl from noncancerous control subjects (P less than 0.0001 for both compounds). In addition, ovarian cancer patients did not show significantly lower serum triglyceride levels than the control subjects. Age did not significantly correlate the serum vitamin A and total cholesterol concentrations, but there was correlation with respect to the serum triglyceride levels. There were moderate correlations between vitamin A and cholesterol levels (r = 0.36, P less than 0.0027) and between cholesterol and triglyceride levels (r = 0.37, P less than 0.0024) in the control subjects but not in the cancer patients. Vitamin A levels correlated moderately with triglyceride levels in both the cancer patients (r = 0.42, P less than 0.0258) and the control subjects (r = 0.33, P less than 0.0069). The inverse relationship between the incidence of ovarian cancer and serum vitamin A and serum total cholesterol concentrations may have distinct implications for preventive medicine and public health.

Serum selenium concentrations in ovarian cancer patients using a simplified fluorimetric procedure

The serum selenium (Se) concentrations were determined to be 105.6±15.6 μg/L ([Formula: see text]) and 116.7±18.4 μg/L ([Formula: see text]) for the ovarian cancer patients and the control subjects in Singapore, respectively (p<0.0065). When we separated the patients into three age groups, namely <30, 30-50, and >50 yr, the ovarian cancer patients showed significantly lower mean serum Se levels than the control subjects for the 30-50-yr age group only. However, when the analysis of variance was used to evaluate the data, the values indicated that the age of the subject did not significantly affect the serum Se level. Our findings suggest that there is an inverse relationship between serum Se concentration and the incidence of human ovarian cancer.A modified simple fluorimetric method for the determination of serum Se concentration is described. The procedure, with a sensitivity limit of 5 μg/L and percentage recoveries of 96.2-100.7%, requires only 0.2 mL of serum sample.