Role of SMU.2055 gene in regulating acid resistance of Streptococcus mutans UA159 / 南方医科大学学报

<p><b>OBJECTIVE</b>To evaluate the effect of SMU.2055 gene on acid resistance of Streptococcus mutans.</p><p><b>METHODS</b>A SMU.2055-dificient mutant strain of S. mutans was constructed using homologous recombination technique. The growth of the wild-type and mutant strains was monitored in both normal and acidic conditions. The lethal pH level, glycolysis, proton permeability, cell permeability and biofilm formation of the two strains were compared.</p><p><b>RESULTS</b>PCR and sequence analyses verified the successful construction of the SMU.2055-dificient mutant strain. The growth and biofilm formation capacity of the mutant strain were obviously lowered in both normal and acidic conditions. The mutant strain also showed increased lethal pH level, proton permeability, and cell permeability with impaired H-ATPase activity in acidic conditions, but its minimum glycolytic pH remained unaffected.</p><p><b>CONCLUSION</b>The SMU.2055-deficient S. mutans mutant exhibits a lowered acid resistance, which affects the growth, lethal pH, proton permeability, H-ATPase activity, cell permeability and biofilm formation but not the minimum glycolytic pH of the mutant strain.</p>

Postmortem interval estimation by time-dependent changes of morphology and biomechanical properties in brain tissues / 医用生物力学

Objective To explore the regularity of time-dependent changes in morphology and biomechanical properties of brain tissues in pigs, and value the feasibility of deducing the postmortem interval (PMI). Methods Brain tissues were taken from 42 pigs and kept in an artificial climate chamber with the temperature of 25 ℃ and humidity of 75%. The samples were collected from telencephalon at sequential time intervals (0, 12, 24, 36, 48, 60 h；n=6) according to the principle of predefined time, position, direction, ratio, quantity and shape. The samples fixed with formaldehyde were then immediately tested by mechanical testing machine to obtain their biomechanical parameters and the histological sections were prepared. Results With the extension of PMI (0-60 h), brain tissues gradually became discolored, weak, mudding and liquefied under the influence of autolysis and putrefaction. Both clearance area of the white matter and its integrated optical density (IOD) significantly increased during 0-48 h. Biomechanical properties of brain tissues including the limit load, average force, elastic modulus and fracture energy all presented a declining tendency at the interval of 12-60 h. The limit load was considered highly statistically significant, and statistical differences were found in average force, elastic modulus and fracture energy. Conclusions There exists a significantly negative structure-activity relationship between the morphology of brain tissues and biomechanical properties. The limit load of postmortem brain tissues in 60 h is the optimum in the window period, which can be used as a new method for estimating PMI.

Postmortem interval estimation by time-dependent changes of morphology and biomechanical properties in brain tissues / 医用生物力学

Objective To explore the regularity of time-dependent changes in morphology and biomechanical properties of brain tissues in pigs,and value the feasibility of deducing the postmortem interval (PMI).Methods Brain tissues were taken from 42 pigs and kept in an artificial climate chamber with the temperature of 25 ℃ and humidity of 75％.The samples were collected from telencephalon at sequential time intervals (0,12,24,36,48,60 h;n =6) according to the principle of predefined time,position,direction,ratio,quantity and shape.The samples fixed with formaldehyde were then immediately tested by mechanical testing machine to obtain their biomechanical parameters and the histological sections were prepared.Results With the extension of PMI (0-60 h),brain tissues gradually became discolored,weak,mudding and liquefied under the influence of autolysis and putrefaction.Both clearance area of the white matter and its integrated optical density (IOD) significantly increased during 0-48 h.Biomechanical properties of brain tissues including the limit load,average force,elastic modulus and fracture energy all presented a declining tendency at the interval of 12-60 h.The limit load was considered highly statistically significant,and statistical differences were found in average force,elastic modulus and fracture energy.Conclusions There exists a significantly negative structure-activity relationship between the morphology of brain tissues and biomechanical properties.The limit load of postmortem brain tissues in 60 h is the optimum in the window period,which can be used as a new method for estimating PMI.

Role of SMU.2055 gene in cariogenic capacity of Streptococcus mutans / 南方医科大学学报

<p><b>OBJECTIVE</b>To construct a SMU.2055-dificient mutant strain of Streptococcus mutans (S. mutans) and evaluate its cariogenic capacity in comparison with wild-type S. mutans.</p><p><b>METHODS</b>The SMU.2055-dificient mutant strain of S. mutans was constructed using homologous recombination technique and observed with scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The absorbance at 600 nm and pH values of the wild-type and mutant strains were monitored to evaluate their growth and acid production. After acid adaption, the two strains were challenged with acid shock and their survival rates were determined.</p><p><b>RESULTS</b>PCR and sequence analyses verified the successful construction of the SMU.2055-dificient mutant strain. Observation with SEM revealed obvious changes in the morphology of the mutant strain, which showed reduced irregular substances between the individual bacteria as compared with the wild-type strain. TEM revealed major alterations in the cellular architecture of the mutant strain with blurry cell membrane and disruption of the membrane integrity. The growth capacity of the mutant strain decreased in both normal and acidic conditions but its acid production capacity remained unaffected.</p><p><b>CONCLUSION</b>SMU.2055 gene is associated with morphology maintenance, growth capacity and acid resistance of S. mutans but is not related to the acid production capacity of the bacterium.</p>

Pharmacokinetic and pharmacodynamic characteristics of berberine and jateorhizine in Coptidis Rhizoma powder and their monomeric compounds in type 2 diabetic rats / 中国中药杂志

This article focused on a comparative analysis on the pharmacokinetic and pharmacodynamic characteristics of berberine (BER) and jateorhizine(JAT) in Coptidis Rhizoma powder (HL-P) and their monomeric compounds (BER + JAT, BJ) in type 2 diabetic (T2D) rats to explore the beneficial. effect of HL-P in the treatment of T2D. The T2D rats were treated with HL-P, BER, JAT and BJ, respectively for 63 d. The pharmacokinetic parameters, dynamic changes in blood glucose level and blood lipid values were measured. The results showed that, compared with other corresponding group, t(max), T(½ka) of BER and JAT in HL-P group were reduced, while C(max), AUC(inf), AUC(last), V(L)/F were significantly increased; compared with model group, blood glucose levels were decreased significantly in HL-P group since the 18th day, while those in BER or BJ group were reduced since the 36th day, however, blood glucose levels showed no obvious changes in JAT group; compared with model group, FFA values in all treatment group were decreased significantly. Moreover, TG, HDL and LDL value in HL-P group, LDL value in BER group and HDL value in BJ group were improved significantly. The above results showed that Coptidis Rhizoma powder showed excellent pharmacokinetic characteristics and excellent activity of lowering blood glucose and lipid. It provided a scientific basis for oral application of Coptidis Rhizoma powder in the treatment of T2D.

Relation between expression of cerebral beta-APP in the chronic alcoholism rats and death caused by TSAH / 法医学杂志

OBJECTIVE@#By observing the cerebral beta-amyloid precursor protein (beta-APP) expression in the chronic alcoholism rats with slight cerebral injury, to discuss the correlation of chronic alcoholism and death caused by traumatic subarachnoid haemorrhage (TSAH).@*METHODS@#Sixty male SD rats were randomly divided into watering group, watering group with strike, alcoholism group and alcoholism group with strike. Among them, the alcohol was used for continuous 4 weeks in alcoholism groups and the concussion was made in groups with strike. In each group, HE staining and immunohistochemical staining of the cerebral tissues were done and the results were analyzed by the histopathologic image system.@*RESULTS@#In watering group, there was no abnormal. In watering group with strike, mild neuronic congestion was found. In alcoholism group, vascular texture on cerebral surface was found. And the neurons arranged in disorder with dilated intercellular space. In alcoholism group with strike, diffuse congestion on cerebral surface was found. And there was TSAH with thick-layer patches around brainstem following irregular axonotmesis. The quantity of beta-APP IOD in alcoholism group was significantly higher in the frontal lobe, hippocampus, cerebellum, brainstem than those in watering group with strike and alcoholism group with strike.@*CONCLUSION@#The cerebral tissues with chronic alcoholism, due to the decreasing tolerance, could cause fatal TSAH and pathological changes in cerebral tissues of rats under slight cerebral injury.

The recent development on age estimation / 法医学杂志

The main methods of age estimation at present mostly rely on characteristic physical and chemical changes of skeleton, soft tissue, cells, biomacromolecules and the other substances. Because physiological changes of tissues and organs during growth are extremely complicated, all methods have their limitations. In practical, it is necessary to combine several methods together in order to improve the accuracy of age estimation. This article reviewed recent development on age estimation domestically and abroad and discussed advantage and disadvantage of different methods.

Changes of cyclin D1 expression following human brain contusion / 法医学杂志

OBJECTIVE@#To study the relationships of Cyclin D1 expression with the posttraumatic intervals (PTI) following the cerebra, brainstem or cerebella contusion in human.@*METHODS@#88 cases of brain contusions of the closed head injury were investigated with pathological and Cyclin D1 immunohistochemistry methods. The results were analyzed by image analysis technique (IAT).@*RESULTS@#The immunoreactivity of Cyclin D1 was almost disappeared in the core cells of the brain contusion. Cyclin D1-positive cells started to increase in the boundary of the brain contusion in the 1h group. Cyclin D1-positive cells were increased significantly in the 3 h-30 d groups and maintained at a high level in the boundary of the brain contusion of those groups. It is suggested that the Cyclin D1-positive cells were primarily origin from microglia and other glia. A few neurons expressed Cyclin D1.@*CONCLUSION@#Cyclin D1 can express in several kinds of brain cells following the contusion, especially in the glia cells. Cyclin D1-positive cells were increased obviously and rapidly after injury, so it could be used as a reference marker for early stage brain injury.

Relationship between expression of nestin in experimental brain contusion and injury time / 法医学杂志

OBJECTIVE@#To observe the alteration of nestin intervals in the experimental traumatic brain injury and investigate its relation to the injury intervals.@*METHODS@#The rat brain contusion was conducted by falling impact injury. After various survival interval (0.5, 6, 12 h and 1, 3, 7, 14, 28 d), immunohistochemical SP method was used for observing the expression of nestin in the cortex, hippocampal dentate gyrus and the corpus callosum on injury side.@*RESULTS@#Expression of nestin positive cells increased at 0.5 h and reached the maximum level in 7 d after brain contusion, then the expression decreased gradually. The intensity of nestin staining in the the cortex and the hippocampal dentate gyrus decreased to normal on 28 d. As to the corpus callosum of injury side it remained weak on 28 d.@*CONCLUSION@#The changes of nestin immunohistochemical staining can be used as an index for forensic estimation of early injury time.

Primarily study and significance of ET-1 during ischemia with RT-PCR / 法医学杂志

OBJECTIVE@#To explore the relationship between expression of endothelin in heart and ischemia.@*METHODS@#Using the RT-PCR method, we enquiry changes of ET-1 RNA after 60min ischemia in hearts of rats.@*RESULTS@#Although the two group appear positive, they are different significantly, which indicate that ischemia may lead to the increase of ET-1 mRNA.@*CONCLUSION@#The experiment, therefore, pave a way for immunochemical study.

HLA-B Alleles Associated with Susceptibility or Resistance to Human Immunodeficiency Virus Type 1 in a Xinjiang Uygur Population, China / 中国病毒学

Host genetic factors, such as human leukocyte antigen (HLA) alleles, are important in Human immunod-eficiency virus (HIV) infection and its progression to AIDS. HLA class I genes, especially highly polymorphicHLA-B genes, are involved in the activation of HLA-restricted cytotoxic T lymphocytes (CTLs) against HIV, andthus control susceptibility to or protect against this virus. The present study was aimed to determine the distributionof HLA-B alleles in the Chinese Uygur ethnic group and its association with HIV infection. One hundred ten healthycontrol (HIV negative) and 128 HIV positive Chinese Xinjiang Uygur ethnic individuals were used in this study.HLA typing for B allele was performed by polymerase chain reaction (PCR) with sequence-specific primers (SSP).Hardy-Weinberg equilibrium was calculated using POPGENE software for the healthy control group. The HLA-Bfrequency of each allele was compared between the patients and the controls using the chi-square test. In HIV-1-pos-itive group, gene frequency of allele B * 4901 was significantly higher compared to the healthy control subjects (P=0.02, OR=3.06, 95%CI=1.16～8.10 forB*4901). In contrast, the gene frequency of B * 40 in healthy controlswas significantly higher than in the HIV-positive patients (P=0.02, OR=0.39, 95%CI=0.07～0. 92 for B* 40).In this study, HLA allele B * 4901 may be associated with increased susceptibility to HIV-1 infection, whereas the B* 40 allele may be associated with resistance to H HIV-1 infection.

Association of HLA-B alleles with human immunodeficiency virus type 1 infection in the Yi ethnic group in Sichuan province / 生物医学与环境科学（英文）

<p><b>OBJECTIVE</b>To determine the distribution of HLA-B alleles in the Chinese Yi ethnic group and its association with HIV infection.</p><p><b>METHODS</b>One hundred and six unrelated healthy HIV negative and 73 HIV positive Chinese Yi ethnic individuals were typed by PCR-SSP.</p><p><b>RESULTS</b>The frequency of alleles B*07, Bx 35, and B*46 were increased in HIV-1-positive subjects, whereas the alleles B*55, B*44 and B*78 were absent in the HIV-infected persons studied. The B*46 allele was present in a significantly higher gene frequency among HIV-1-positive individuals (P=0.02, OR=3.32, 95% CI=1.13-9.78) compared with control subjects.</p><p><b>CONCLUSION</b>HLA-B*46 may be associated with its susceptibility to HIV-1 infections.</p>

Effect of peroxynitrite on the reactivity of rabbit pulmonary arteries in vitro / 生理学报

To investigate the effect of peroxynitrite (ONOO(-)) on the reactivity of rabbit pulmonary artery, the responses of rabbit pulmonary artery rings (PARs) pre-incubated with ONOO(-) to endothelium-dependent and receptor-dependent relaxants ACh and ADP, endothelium-dependent and receptor-independent relaxant calcium ionophore A23187, endothelium-independent relaxant sodium nitroprusside (SNP) and alpha(1)-adrenoceptor agonist phenylephrine (PE) were observed in vitro in an accumulative manner. (1) Relaxations of PARs to ACh, calcium ionophore A23187 and ADP were markedly impaired with shift of accumulative dose-response curve of each agonist to the right. Inhibition of endothelium-dependent and receptor-dependent or independent relaxation by ONOO(-) was dose-dependent. (2) ONOO(-) incubation inhibited SNP-induced relaxation in a dose-dependent manner. (3) Contractile response of PARs to PE varied with the different doses of ONOO(-). In PARs pre-incubated with 0.5 mmol/L ONOO(-), contractile response was significantly enhanced with shift of PE accumulative dose-response curve to the left, whereas in PARs pre-incubated with 1.0 mmol/L or 2.0 mmol/L ONOO(-), it was markedly reduced with right shift of PE accumulative dose-response curve. (4) Vehicle of ONOO(-) had no effect on responses to each agonist.Decomposed ONOO(-) had minimal effect on the response to PE and ADP, in contrast, relaxation of PARs to ACh, A23187 and SNP were enhanced. These results indicate that ONOO(-) may contribute to regulatory disorder of pulmonary artery reactivity.

Endogenous peroxynitrite mediates lipopolysaccharide-induced injury in cultured pulmonary artery endothelial cells / 生理学报

This study, using cultured bovine pulmonary artery endothelial cells (BPAECs), was undertaken to investigate the roles of endogenous ONOO(-) in LPS-caused injury in endothelial cells. The fluorescent intensity of nitrotyrosine (NT), a specific marker of ONOO(-) generation, in BPAECs represented the content of endogenous ONOO(-) generation. The fluorescent intensity of NT and the number of NT positive cells were detected with flow cytometry (FCM), and the percentage of NT positive cells was calculated. The results are as follows. (1) LPS (1, 5 and 10 microg/ml) caused a marked increase in fluorescent intensity of NT in a dose-dependent manner, which was significantly increased compared to the vehicle group (P<0.01).The number and percentage of NT positive cells were markedly increased (both P<0.05 vs vehicle group). Aminoguanidine (AG), a selective inhibitor of inducible nitric oxide synthase (iNOS), inhibited LPS-induced increase in fluorescent intensity of NT in BPAECs. However, the number and percentage of NT positive cells had a tendency to reduce. (2) LPS brought about an enhancement in MDA content and the activity of LDH in cultured supernatant. AG reversed the enhancement in MDA content induced by LPS (P<0.01). In contrast, AG had a marginal effect on the activity of LDH. (3) LPS induced an increase in apoptotic rate in BPAECs in a dose-dependent manner. The number of apoptotic cells markedly increased as well. Some BPAECs stained with fluorescent probe ethidium bromide showed morphological features of apoptosis with chromatin condensation and nuclear fragmentation. AG reduced the apoptotic rate and the number of apoptotic cells, both of which were still higher than those of vehicle group (P<0.05). LPS led to inhibition of mitochondrial respiration and membrane potential in an accumulation manner. In conclusion, LPS caused injury to cultured BPAECs and increased the production of ONOO(-).The cytotoxicity of LPS may be mediated by the endogenous ONOO(-).

Effect of naloxone on cognitive function in vascular dementia in rats.

BACKGROUND & OBJECTIVES: The endogenous opioid system plays an important role in cognitive functions and may also contribute to the progression of some kind of dementia. Naloxone has been shown to exert beneficial effects on memory deficits in patients with senile dementia and reverse some of the effects induced by endogeneous opioids. We therefore investigated the effects of naloxone on cognitive function in rats with vascular dementia (VD). METHODS: Vascular dementia was established by permanent occlusion of the common carotid arteries. Rats were divided into three groups viz., sham-operated controls, naloxone treated VD rats (naloxone 0.8 mg/kg, i.p. daily for 7 days), and nontreated VD rats. The Morris water maze test was performed to study spatial learning and memory. The extracellular recording technique was used to record long-term potentiation (LTP) of the Schaffer collateral-CA1 synapse in the rat hippocampal slices. RESULTS: In the hidden platform trials, escape latencies of the naloxone treated VD rats were significantly shorter than that of the nontreated VD rats (P < 0.001). In the probe trials, the number of enteries in the target area of the naloxone treated VD rats (8.36 +/- 1.38 times/min) were more than that of the nontreated VD rats (4.64 +/- 1.73 times/min) (P < 0.01). The magnitudes of LTP recorded in the CA1 pyramidal neurons of the naloxone treated VD rats were significantly augmented when compared to the nontreated VD rats (P < 0.05). INTERPRETATION & CONCLUSION: Naloxone could facilitate spatial learning and memory and enhance LTP in the CA1 region of hippocampus in rats with VD. It is postulated that naloxone might exert beneficial effects on cognitive function in VD in rats by modulating the synaptic plasticity in the hippocampal neuronal network.

Study on the change of bFGF in reticular formation of medulla oblongata after primary brain-stem injury / 法医学杂志

OBJECTIVE@#To study the effect of primary brain-stem injury on the expression of basic fibroblast growth factor (bFGF) in the reticular formation of medulla oblongata.@*METHODS@#Immunohistochemical SABC was used to study the change of bFGF expression in the reticular formation of medulla oblongata after brain-stem injury by striking.@*RESULTS@#The numbers of positive cells and positive intensity of the study group in the reticular formation of medulla oblongata were significantly elevated than those of the control group and the postmortem injury group.@*CONCLUSION@#The expression of bFGF is elevated in reticular formation after brain-stem injury.