[Analysis on the polymorphisms of human B cell epitopes of 5 specificity antigens in Mycobacterium tuberculosis in China]

OBJECTIVE

To study the diversities of human B cell epitopes of five proteins (Mpt83, Mpt70, LpqH, PstS3, GroES) in Mycobacterium tuberculosis isolates from China.

METHODS

We selected 179 strains isolated from patients with tuberculosis in different regions of China, and cultured these strains by L-J medium. The gene sequences of these 5 proteins were amplified and sequenced by PCR. The variations (single nucleotide polymorphisms, SNP) of the DNA sequences were compared and analyzed according to the immune epitope database (IEDB). The synonymous mutation rate (dS), non-synonymous mutation rate (dN) and dN/dS values were calculated with MEGA6 software.

RESULTS

Among the 179 clinical MTBC isolates, 7 SNP mutations were found in the mpt83gene. The dN/dS value of the whole mpt83 gene was 0.88. One SNP mutation was found in the mpt70 gene. The dN/dS values of the whole pstS3 gene and non-B epitopes areas were 1.74 and 1.40 respectively. But no mutation was found in the groES gene.

CONCLUSION

The mpt83, lpqH and pstS3 genes of 179 MTBC strains contain gene SNPs and human B cell epitopes diversities, while the coding gene and human B cell epitopes of protein mpt70 and groES were conservative.

Origin of ultralow Young׳s modulus in a metastable β-type Ti-33Nb-4Sn alloy

Although there is difficulty in growing a Ti-33Nb-4Sn single crystal due to its ultralow β-phase stability, the single-crystal elastic constants of metastable β-type Ti-33Nb-4Sn (wt%) alloy were extracted successfully from its polycrystal by in-situ synchrotron X-ray diffraction technique, to clarify the origin of the ultralow Young's modulus in its polycrystal. It is indicated that compared to binary TiCr, TiV and TiNb alloys, the Ti-33Nb-4Sn alloy possesses slightly lower β-phase stability with respect to {110}<110>(-)shear (i.e., C׳) but much lower β-phase stability regarding to {001}〈100〉 shear (i.e., C44). An analysis by the Hill approximation suggests that the ultralow isotropic polycrystalline Young׳s modulus (EH) of Ti-33Nb-4Sn alloy originates from the extremely low shear modulus C44 as well as the relatively low C׳. This indicates that in addition to C׳, C44 has a significant contribution to the Young's modulus of polycrystal, which challenges a conventional understanding that the Young's modulus of β-type Ti alloys is predominantly determined by C׳.

Factors affecting the recurrence and survival of hepatocellular carcinoma after hepatectomy: a retrospective study of 601 Chinese patients

OBJECTIVE

Indications for resection of hepatocellular carcinoma (HCC) remain controversial. This study aimed to identify prognostic factors that affect overall survival (OS) and disease-free survival (DFS) in patients with HCC after hepatectomy.

METHODS

From 2004 to 2010, 601 patients with HCC who underwent resection were enrolled. Factors stratified into the host, biochemical, surgical treatment and tumor-related features in terms of recurrence and overall survival were analyzed. Prognostic factors were evaluated by univariate and multivariate analyses, with Kaplan-Meier survival analyses and Cox proportional hazard model.

RESULTS

The overall survival rates of 1-, 3- and 5- year were 79, 62, and 54 %, and the corresponding DFS rates were 51, 38 and 31 %, respectively. In a multivariate analysis, Child-Pugh, serum AFP level, ALT level, time for hepatic resection, tumor differentiation, maximum size of tumors, local necrosis, portal vein tumor thrombus, and TNM Stage were correlated significantly with patients' OS. Gender (P = 0.046), cigarette smoking (P = 0.007), serum AFP level (P = 0.001), GGT level (P = 0.002), maximum size of tumors (P = 0.009), liver cirrhosis (P = 0.025), portal vein tumor thrombus (P = 0.022), microvascular tumor thrombus (P = 0.007) and TNM Stage (P = 0.001) were significantly affected DFS.

CONCLUSION

Preoperative AFP level, maximum size of tumors, portal vein tumor thrombus and TNM Stage were revealed as important prognostic factors for OS and DFS through follow-up of a relatively large cohort of Chinese HCC patients.

Field evidence for earlier leaf-out dates in alpine grassland on the eastern Tibetan Plateau from 1990 to 2006

Worldwide, many plant species are experiencing an earlier onset of spring phenophases due to climate warming. Rapid recent temperature increases on the Tibetan Plateau (TP) have triggered changes in the spring phenology of the local vegetation. However, remote sensing studies of the land surface phenology have reached conflicting interpretations about green-up patterns observed on the TP since the mid-1990s. We investigated this issue using field phenological observations from 1990 to 2006, for 11 dominant plants on the TP at the levels of species, families (Gramineae-grasses and Cyperaceae-sedges) and vegetation communities (alpine meadow and alpine steppe). We found a significant trend of earlier leaf-out dates for one species (Koeleria cristata). The leaf-out dates of both Gramineae and Cyperaceae had advanced (the latter significantly, starting an average of 9 days later per year than the former), but the correlation between them was significant. The leaf-out dates of both vegetation communities also advanced, but the pattern was only significant in the alpine meadow. This study provides the first field evidence of advancement in spring leaf phenology on the TP and suggests that the phenology of the alpine steppe can differ from that of the alpine meadow. These findings will be useful for understanding ecosystem responses to climate change and for grassland management on the TP.

[The relationship of ECG and pregnancy outcome of older pregnant woman in late pregnancy]

OBJECTIVE

To observe the changes of electrocardiogram (ECG) and pregnancy outcome of the late pregnancy women.

METHODS

Late pregnancy women were divided into two groups by age: over 35 group and under 35 group. The incidence of abnormal electrocardiogram was recorded when the patients were subjected to routine ECG examination. Then the pregnancy, delivery outcome and if there's low birth weight newborn were recorded later.

RESULTS

The incidence of abnormal ECG in over 35 group was significantly higher than that in under 35 group (P < 0.05). And the incidence of ST segment changes, arrhythmia in the group of former was higher than that in the group of latter (P < 0.05). Among the different type of arrhythmia, the incidence of sinus bradycardia and ventricular premature beat in the group of former were higher than those in the group of latter (P < 0.05). But the incidence of sinus tachycardia in the former group was obviously lower than that in the latter group (P < 0.05). The incidence of pregnancy loss in over 35 with abnormal ECG group was significantly higher than that in under 35 with normal or abnormal ECG groups (P < 0.05). The incidence of premature birth in over 35 with abnormal ECG group was significantly higher than that in over 35 with normal ECG group (P < 0.05). The incidence of low body weight in over 35 with abnormal ECG group was significantly higher than that in under 35 with normal ECG group (P < 0.05).

CONCLUSION

The late pregnancy women with the age of over 35 are more likely to have ECG abnormalities, such as arrhythmia, myocardial ischemia and so on. The older pregnant women with abnormal ECG easily suffer from pregnancy losing, premature birth and having a low birth weight baby.

Intra-abdominal high pressure induces intestinal barrier dysfunction in rats

AIM: To study the effect of different degrees of intra-abdominal high pressure on intestinal mucosal barrier dysfunction and to explore the possible mechanisms involved.

METHODS: Forty-five adult male SD rats were randomly divided into a normal control group, a 10 mmHg and a 20 mmHg group (n = 15 for each). Nitrogen pneumoperitoneum was induced to generate intra-abdominal high pressure in animal models. The two pneumoperitoneum groups were further divided into three subgroups (five rats in each subgroup) for testing when pneumoperitoneum was maintained for 1, 2 and 4 h, respectively. Twenty-four hours after the relief of pneumoperitoneum, a spectrophotometer was used to measure the concentration of blue dextran 2000 in different segments of the small intestine. Malondialdehyde (MDA), reduced glutathione (GSH) and superoxide dismutase (SOD) in intestinal tissue homogenates, as well as plasma diamine oxidase (DAO) and D-lactic acid were measured. Morphological changes in the intestinal tissue were observed by light microscopy and electron microscopy.

RESULTS: Compared to the control group, intestinal transit was significantly delayed, but intestinal SOD, GSH and MDA levels and plasma D-lactate level showed no significant changes in the two high intra-abdominal pressure groups (all P > 0.05). Plasma DAO level did not differ significantly between the 10 mmHg group and control group, but was significantly different between the 20 mmHg and control groups (1412.93 ± 1397.19 vs 542.41 ± 314.93, P < 0.05). Under the light microscope, postoperative intestinal mucosa showed no damage in the control group; however, mild (increase in small intestinal subepithelial gaps and villus capillary congestion) and severe (varying degrees of intestinal mucosal changes, small intestinal mucosal congestion and edema, expansion of small intestinal subepithelial gaps, and intestinal villus degeneration, necrosis or loss) pathological changes were observed in the 10 and 20 mmHg groups, respectively. Electron microscopy demonstrated that intestinal villus cells in the 10 mmHg group showed mild swelling of tight junctions, and the 20 mmHg group showed significant changes in the microvillus and mitochondrial structures.

CONCLUSION: High intra-abdominal pressure can delay intestinal transit, alter plasma DAO activity, cause significant damage to intestinal epithelial cells, and increase intestinal permeability.

Proteomic analysis of synovial fibroblast-like synoviocytes from rheumatoid arthritis

OBJECTIVES

The purpose of this study was to identity protein expression patterns of fibroblast-like synoviocytes (FLSs) derived from the synovial tissue of patients with rheumatoid arthritis (RA) and osteoarthritis.

METHODS

Two-dimensional gel electrophoresis (2-DE) in combination with matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF-MS) was used to visualise and identify differential cellular protein expression profiles in FLSs between RA and control groups. Western-blot analysis was performed to further verify selected differentially-expressed proteins.

RESULTS

A total of 1633 and 1603 protein spots were examined in synovial FLSs of RA patients and controls, respectively. Ninety-two spots in the RA group were statistically over- or under-expressed compared with controls. Among them, 33 proteins over-expressed by more than 3-fold were then identified by MALDI-TOF-MS analysis. These proteins included enzymatic and structural proteins (e.g. PKM1/M2, α-enolase, ERp60, lamin-A/C), signal transduction proteins (e.g. annexin 11, peroxiredoxin 1, TrpRS), heat-shock/chaperone proteins (e.g. TCP-1, GRP75, HspB5, Bip) and some unknown protein species. Three proteins, namely α-enolase, GRP75 and PKM2, were verified by Western blot and the results were found to be consistent with proteomic analysis.

CONCLUSIONS

The differentially expressed proteins identified in RA synovial FLSs might be candidate RA-associated proteins and may prove to be promising diagnostic indicators or new therapeutic targets for RA.

[Effect of down-regulation of Id3 expression by microRNA on proliferation and apoptosis of A549 cells]

AIM

To investigate the effect of microRNA-mediated exogenous Id3 gene silencing on proliferation and apoptosis of human lung adenocarcinoma A549 cells in vitro.

METHODS

A recombinant miRNA expression vector (pcDNA6.2-GW/EmGFPmiR-Id3, pcDNA/miRId3) which targets human Id3 gene was constructed. After 24 h of transfection, the transfection efficiency was monitored by inverted fluorescence microscopy.EGFP expression efficiency in A549 cells was analyzed by flow cytometry (FCM).Id3 expression vector pEGFP/Id3 and pcDNA/miRId3 were cotransfected into A549 cells by liposome-mediated method. After 24 h of transfection, the transfection efficiency was monitored by inverted fluorescence microscopy.Semi-quantitative RT-PCR and Western blot were used for identifying Id3 mRNA and protein expression respectively in A549 cells after transfection. Cell proliferation rate and apoptosis ratio were evaluated by MTT assay and Annexin V/7-ADD staining followed by FCM to observe the down-regulatory effect of Id3 expression by miRNA-mediated RNA interference (RNAi).

RESULTS

pcDNA/miRId3 and pEGFP/Id3 were successfully transfected into A549 cells. RT-PCR and Western blot results showed that after 24 h of cotransfection of pEGFP/Id3 and pcDNA/miRId3 in A549 cells, the exogenous expression of Id3 both at mRNA and protein levels were significantly reduced compared with the pEGFP/Id3 group. MTT assay and Annexin V/7-AAD staining showed that after 24 h of transfection with pEGFP/Id3, the proliferation rates were significantly reduced and apoptotic cell ratios were significantly higher than those of pEGFP-transfected cells.Whereas there were not any significant differences in proliferation rates or apoptotic cell ratios between pcDNA/miRId3+pEGFP/Id3 cotransfected group and pEGFP or miRNA negative controls.

CONCLUSION

Exogenous expression of Id3 in A549 cells could inhibit proliferation and induce apoptosis of A549 cells. Cotransfection of pcDNA/miRId3 and pEGFP/Id3 into A549 could reverse the Id3-induced proliferation inhibition and apoptosis. Construction and application of Id3-targeting miRNA expression vector may build some foundations for investigation the mechanisms of Id3-induced proliferation inhibition and apoptosis in A549 cells.

[The change of thioredoxin system in myocardial tissue of type 2 diabetic rats undergoing myocardial injury]

The aim of the present study is to investigate the change of thioredoxin (Trx) system in myocardial tissue of type 2 diabetic rats after myocardial injury and the underlying mechanism. Adult Sprague Dawley rats were randomly divided into two groups: normal control (NC) group and diabetes (DM) group. Rats in DM group were subjected to high-sugar, high-fat diet and streptozotocin (STZ) injection. Rats in NC group were only given normal diet and equal amount of citric acid buffer injection. At week 1, 2, 4, 12, 21 after STZ injection, plasma glucose concentration and the concentrations of insulin, creatine kinase MB (CK-MB), cardiac troponin I (cTnI) in serum were measured. Myocardial Trx and thioredoxin reductase (TR) activities, as well as caspase-3 activity, were determined by respective assay methods. Protein and mRNA levels of Trx, TR, Trx interacting protein (TXNIP) were determined by Western blot and real time PCR, respectively. The results showed that type 2 diabetic rat model was successfully established at week 1 after STZ injection, and myocardial injury was induced from week 2. Moreover, caspase-3 activity was significantly increased at week 4, 12 in diabetic rats. The activities of myocardial Trx and TR in diabetic rats was decreased from week 2, and continually aggravated as the disease developed. Compared with those in NC group, the mRNA levels of Trx1, Trx2, TR1, TR2 in DM group decreased at week 4, and then increased in week 12. In DM group, the protein levels of Trx1, Trx2, TR1 and TR2 increased significantly at week 12. The mRNA expressions of myocardial TXNIP in diabetic rats were significantly increased at week 4, 12, 24 and protein expression was increased at week 12. These results suggest diabetes can decrease myocardial Trx, TR activity, inducing myocardial cell apoptosis and heart injury. The inhibitory effect of diabetes is mainly associated with TXNIP up-regulation and Trx nitration.

Mechanisms of yeast stress tolerance and its manipulation for efficient fuel ethanol production

Yeast strains of Saccharomyces cerevisiae have been extensively studied in recent years for fuel ethanol production, in which yeast cells are exposed to various stresses such as high temperature, ethanol inhibition, and osmotic pressure from product and substrate sugars as well as the inhibitory substances released from the pretreatment of lignocellulosic biomass. An in-depth understanding of the mechanism of yeast stress tolerance contributes to breeding more robust strains for ethanol production, especially under very high gravity conditions. Taking advantage of the "omics" technology, the stress response and defense mechanism of yeast cells during ethanol fermentation were further explored, and the newly emerged tools such as genome shuffling and global transcription machinery engineering have been applied to breed stress resistant yeast strains for ethanol production. In this review, the latest development of stress tolerance mechanisms was focused, and improvement of yeast stress tolerance by both random and rational tools was presented.

Hypoxia-inducible factor 1α cDNA cloning and its mRNA and protein tissue specific expression in domestic yak (Bos grunniens) from Qinghai-Tibetan plateau

Adaptation to hypoxia is regulated by hypoxia-inducible factor 1 (HIF-1), a heterodimeric transcription factor consisting of an oxygen-regulated alpha-subunit and a constitutively expressed beta-subunit. How animals living on Qinghai-Tibetan plateau adapt to the extreme hypoxia environment is known indistinctly. In this study, the Qinghai yak, which has been living at 3000-5000 m altitude for at least two millions of years, was selected as the model of high hypoxia-tolerant adaptation species. The HIF-1alpha ORFs (open reading frames) encoding for two isoforms of HIF-1alpha have been cloned from the brain of the domestic yak. Its expression of HIF-1alpha was analyzed at both mRNA and protein levels in various tissues. Both its HIF-1alpha mRNA and protein are tissue specific expression. Its HIF-1alpha protein's high expression in the brain, lung, and kidney showed us that HIF-1alpha protein may play an important role in the adaptation to hypoxia environment.

Seasonal changes in weight and body composition of yak grazing on alpine-meadow grassland in the Qinghai-Tibetan plateau of China

Forty-five male yaks (born April 2001) were studied to determine how seasonal changes on the Qinghai-Tibetan plateau affected BW and body composition. Thirty yaks were weighed monthly from birth to 26 mo of age to determine seasonal changes in BW. The remaining 15 yaks were allocated randomly to five groups (three yaks per group), designated for slaughter at 13, 15, 18, 22, and 25 mo to measure seasonal effects on body chemical composition. All yaks were grazed on the alpine-meadow grassland of the plateau without any supplementation. All BW and body composition data were calculated on an individual basis. Body weight and body composition data were both compared across seven growth periods spanning 2 yr and defined by season. From April (birth) to December 2001 of the first growing season, yak BW increased (P < 0.01); however, during the subsequent cold season (December 2001 to May 2002), BW decreased (P < 0.01). The second growing season ran from May 2002 (13 mo of age) to October 2002 (18 mo of age), and the second live weight-loss season ran from October 2002 until May 2003. The weight loss experienced by yaks during the first weight-loss season was 25.64% of the total weight gain in the first growing season. The weight loss experienced by yaks during the second weight-loss season was 29.73% of the total weight gain in the second growing season. Energy retention in the second growing season was 291.07 MJ, 50.8% of which was consumed during the subsequent cold season. Energy accumulation in the summer (from May to July) and fall (from July to October) of the second growing season did not differ (5.01 and 6.30 MJ/kg of EBW gain, respectively; P = 0.63). The energy mobilized during the second winter (from October 2002 to February 2003) was 16.49 MJ/kg of EBW, and in the second spring (from February to May 2003), it was 9.06 MJ/kg of EBW. These data suggest that the decrease in grazing yak BW during the first cold season is much less than during the second cold season, and that the energy content per unit of BW mobilized is greater (P = 0.02) in winter than in spring. Results from this study demonstrate highly efficient compensatory growth in grazing yaks following the first weight loss period during the first cold season. This benefit could be exploited by herders to improve yak production. Yaks may have developed a type of self-protection mechanism to overcome the long cold seasons in the Qinghai-Tibetan plateau.

[Expression of MMP-2 and MMP-3 in periodontal tissues of rat periodontitis model]

OBJECTIVE

To investigate the expression of MMP-2 and MMP-3 in periodontal tissues of rat periodontitis model at different stages of inflammation of varied severity.

METHODS

The periodontal tissues were immunohistochemically stained by antibody of MMP-2 and MMP-3.

RESULTS

MMP-2 and MMP-3 were both strongly positive in gingival epithelia and fibroblasts in periodontal ligament in rat periodontitis model. And chronic periodontitis showed lower expression of MMP-2 and MMP-3 than that of acute gingivitis and acute peridontitis.

CONCLUSION

The expression of MMP-2 and MMP-3 varies in different stage of periodontitis. MMP-2 and MMP-3 may play an important role in development of periodontitis.

Leptin cDNA cloning and its mRNA expression in plateau pikas (Ochotona curzoniae) from different altitudes on Qinghai-Tibet Plateau

Leptin, an adipocyte-derived hormone, plays an important role in body energy homeostasis. Plateau pika (Ochotona curzoniae), an endemic and keystone species living only at 3000-5000 m above sea level on Qinghai-Tibet Plateau, is a typically high hypoxia and low temperature tolerant mammal with high resting metabolic rate (RMR), non-shivering thermogenesis (NST), and high ratio of oxygen utilization to cope with harsh plateau environment. To explore the molecular mechanism of ecological acclimation in plateau pika, we first cloned pika leptin cDNA and compared its mRNA expression in different altitudes (3200 and 3900 m) using real-time RT-PCR (Taqman probe) technology. The full-length pika leptin cDNA was 3015 with 504 bp open-reading frame encoding the precursor peptide of 167 amino acids including 21 residues of signal peptide. Pika leptin was 70-72% homologous to that of other species and was of similarly structural characteristics with other species. The pika-specific genetic diversity in leptin sequence occurred at twenty sites. With the increase in altitude, there were larger fat store and high level of ob gene expression in plateau pika. Our results indicated that leptin is sensitive to cold and hypoxia plateau environment and may play one of important roles in pika's ecological adaptation to harsh plateau environment.

[Expression of type III collagen mRNA in rat periodontal ligamemt in response to different occlusal force]

OBJECTIVE

To investigate the altered expression level of type III collagen mRNA in the periodontal ligament of rat molar in response to changes in occlusal force.

METHODS

A model of the rat experimental occlusal trauma was established, in which the occlusal surface on the upper first molar of (250+/-20) g male SD rats was approximately 1 mm elevated unilaterally. Another model was establishde, in which the upper first molar was extracted to remove occlusal force against the lower first molar. The rats were perfusion-fixed at 12 h and on the 3rd, 7th, 14th and 30th day after treatment. The prepared sagittal sections were processed to study the expression of type III collagen mRNA in rat periondontal ligament by in situ hynbridization.

RESULTS

Following the bite-raising,the number and the desity of the positive cells of type III collagen mRNA in the periodontal ligament of the lower first molar increased gradually. The expression of type III collagen mRNA was the strongest on the 7th day (124.03 +/- 14.82). Comparde to the normal rats,the expression level of type III collagen mRNA in the periodontal ligament of the lower first molar significantly decreased on the 14th day (63.07 +/- 5.69). When occlusal force was removed the expression level of type III collagen mRNA in the periodontal ligament of the lower first molar showed a rapid decrease. Subsequently, a gradual increase was recognized. Compared to the normal animal,a more significant increase (154.39 +/- 17.61) was detected on the 7th day after occlusal force was removed.

CONCLUSION

The results suggest that type III collagen may play important roles in the process of periodontium remodeling against different occlusal force.

Online monitoring and characterization of flocculating yeast cell flocs during continuous ethanol fermentation

Both intrinsic and observed kinetic investigations for those ethanol fermentations using self-flocculated yeast strains have been hindered by the lack of real online monitoring techniques and proper characterization methods for the flocs. An optical detecting technique, the focused beam reflectance measurement probe developed by Lasentec (Redmond, WA) was inserted into a fermentor to monitor the floc chord length distributions. Using a simulating system composed of the floc-buffer suspensions, the total floc chord length counts per second were directly correlated with the floc biomass concentrations so that the floc biomass concentrations can be in situ detected. Furthermore, a characterization method of the flocs was established by properly weighted treatments of the detected floc chord length distributions. When a real yeast floc ethanol fermentation system was detected during its intrinsic kinetic investigations in which the floc size needed to be controlled at a level of micrometer scale to eliminate inner mass transfer limitations, it was found and validated that CO(2) produced during fermentation exerted significant disturbances. By applying 1/length-weighted treatment, these disturbances were effectively overcome.

Cloning of hypoxia-inducible factor 1alpha cDNA from a high hypoxia tolerant mammal-plateau pika (Ochotona curzoniae)

Hypoxia-inducible factor 1 is a transcription factor composed of HIF-1alpha and HIF-1beta. It plays an important role in the signal transduction of cell response to hypoxia. Plateau pika (Ochotona curzoniae) is a high hypoxia-tolerant and cold adaptation species living only at 3000-5000 m above sea level on the Qinghai-Tibet Plateau. In this study, HIF-1alpha cDNA of plateau pika was cloned and its expression in various tissues was studied. The results indicated that plateau pika HIF-1alpha cDNA was highly identical to those of the human (82%), bovine (89%), mouse (82%), and Norway rat (77%). The deduced amino acid sequence (822bp) showed 90%, 92%, 86%, and 86% identities with those of the human, bovine, house mouse, and Norway rat, respectively. Northern blot analyses detected two isoforms named pLHIF-1alpha and pSHIF-1alpha. The HIF-1alpha mRNA was highly expressed in the brain and kidney, and much less in the heart, lung, liver, muscle, and spleen, which was quite different from the expression pattern of mouse mRNA. Meanwhile, a new variant of plateau pika HIF-1alpha mRNA was identified by RT-PCR and characterized. The deduced protein, composed of 536 amino acids, lacks a part of the oxygen-dependent degradation domain (ODD), both transactivation domains (TADs), and the nuclear localization signal motif (NLS). Our results suggest that HIF-1alpha may play an important role in the pika's adaptation to hypoxia, especially in brain and kidney, and pika HIF-1alpha function pattern may be different from that of mouse HIF-1alpha. Furthermore, for the high ratio of HIF-1alpha homology among the animals, the HIF-1alpha gene may be a good phylogenetic performer in recovering the true phylogenetic relationships among taxa.

Energy metabolism and protein balance in growing rats fed different levels of dietary fibre and protein

A study was performed to investigate the effect of different levels of dietary fibre (DF) and dietary protein on visceral organ size, digestibility, nitrogen balance and energy metabolism in rats. Thirty-six male Wistar rats, initial body weight about 76 g were used in a factorial design consisting of three levels of DF (low, 100 g/kg DM: medium, 250 g/kg DM and high, 290 g/kg DM) and two levels of dietary protein (low, 120 g/kg DM and high, 223 g/kg DM). The added fibre source was soybean hulls and Danish fish meal was used as sole source of dietary protein. Measurements of gas-exchange were done on six rats (one group) while urine and faeces were collected individually. The ratio of food/empty body gain increased (P<0.05) with increasing DF and decreasing levels of dietary protein. The weight of the digestive tract was larger (P<0.05) in rats fed the high fibre diet than in those fed the low fibre diet. The digestibility of nutrients and energy decreased linearly with increasing level of soybean fibre (P<0.05). An increased intake of DF was associated with a concomitant loss of protein and energy to faeces. The microbial degradation of NSP and other unabsorbed carbohydrates caused considerably changes in N metabolism of the colon. In rats fed the low protein diets increased levels of DF decreased N excretion in urine and increased N excretion in faeces, while the ratio of retained/digested protein remained constant. When rats were fed the high protein diet protein retention dropped in response to DF both absolute and relative to digested amount, indicating that energy intake could be a limiting factor. Heat production as a percentage of metabolizable energy (HP/ME) was higher (P<0.05) in rats fed the low protein diet than in rats fed the high protein diet, but no significant difference was found among DF levels.

Simvastatin and niacin, antioxidant vitamins, or the combination for the prevention of coronary disease

BACKGROUND

Both lipid-modifying therapy and antioxidant vitamins are thought to have benefit in patients with coronary disease. We studied simvastatin-niacin and antioxidant-vitamin therapy, alone and together, for cardiovascular protection in patients with coronary disease and low plasma levels of HDL.

METHODS

In a three-year, double-blind trial, 160 patients with coronary disease, low HDL cholesterol levels and normal LDL cholesterol levels were randomly assigned to receive one of four regimens: simvastatin plus niacin, vitamins, simvastatin-niacin plus antioxidants; or placebos. The end points were arteriographic evidence of a change in coronary stenosis and the occurrence of a first cardiovascular event (death, myocardial infarction, stroke, or revascularization).

RESULTS

The mean levels of LDL and HDL cholesterol were unaltered in the antioxidant group and the placebo group; these levels changed substantially (by -42 percent and +26 percent, respectively) in the simvastatin-niacin group. The protective increase in HDL2 with simvastatin plus niacin was attenuated by concurrent therapy with antioxidants. The average stenosis progressed by 3.9 percent with placebos, 1.8 percent with antioxidants (P=0.16 for the comparison with the placebo group), and 0.7 percent with simvastatin-niacin plus antioxidants (P=0.004) and regressed by 0.4 percent with simvastatin-niacin alone (P<0.001). The frequency of the clinical end point was 24 percent with placebos; 3 percent with simvastatin-niacin alone; 21 percent in the antioxidant-therapy group; and 14 percent in the simvastatin-niacin-plus-antioxidants group.

CONCLUSIONS

Simvastatin plus niacin provides marked clinical and angiographically measurable benefits in patients with coronary disease and low HDL levels. The use of antioxidant vitamins in this setting must be questioned.

Effects of prolonged intensive lipid-lowering therapy on the characteristics of carotid atherosclerotic plaques in vivo by MRI: a case-control study

High-resolution magnetic resonance imaging (MRI) with flow suppression not only provides useful information on luminal and wall areas of the carotid artery but also can identify the principal tissue components of the carotid atherosclerotic plaque. The effects of intensive lipid-lowering therapy on these MRI tissue characteristics were examined in patients with coronary disease (CAD). Eight CAD patients who have been receiving intensive lipid-lowering treatment (niacin 2.5 g/d, lovastatin 40 mg/d, and colestipol 20 g/d) for 10 years in the Familial Atherosclerosis Treatment Study (FATS) follow-up were randomly selected from among 60 such treated patients. Eight CAD patients who were matched to the treated patients for age (+/-3 years), baseline low density lipoprotein (+/-5 mg/dL), and triglycerides (+/-50 mg/dL) but who had never been treated with lipid-lowering drugs were selected as controls. For each of these 32 carotid arteries, luminal and plaque areas were measured by planimetry, in a blinded protocol, from the magnetic resonance image that showed most plaque. Fibrous tissue, calcium, and lipid deposits were identified on the basis of established criteria. Plaque composition was estimated as a fraction of total planimetered area. Patients treated with 10-year intensive lipid-lowering therapy, compared with control subjects, had significantly lower low density lipoprotein cholesterol levels (84 versus 158 mg/dL, respectively; P<0.001) and higher high density lipoprotein cholesterol levels (51 versus 37 mg/dL, respectively; P<0.001). As a group, treated patients, compared with untreated control subjects, had a smaller core lipid area (0.7 versus 10.2 mm(2), respectively; P=0.01) and lipid composition (1% versus 17%, respectively). Group differences in luminal area (55 [treated] versus 44 [control] mm(2), P=NS) and plaque area (58 [treated] versus 64 [control] mm(2), P=NS) tended to favor treatment. MRI appears useful for estimating carotid plaque size and composition. Hyperlipidemic CAD patients frequently (97%) have at least moderate (>/=40% area stenosis) carotid plaque. In this case-control study, prolonged intensive lipid-lowering therapy is associated with a markedly decreased lipid content, a characteristic of clinically stable plaques.

Antioxidant supplements block the response of HDL to simvastatin-niacin therapy in patients with coronary artery disease and low HDL

One strategy for treating coronary artery disease (CAD) patients with low HDL cholesterol (HDL-C) is to maximally increase the HDL-C to LDL-C ratio by combining lifestyle changes with niacin (N) plus a statin. Because HDL can prevent LDL oxidation, the low-HDL state also may benefit clinically from supplemental antioxidants. Lipoprotein changes over 12 months were studied in 153 CAD subjects with low HDL-C randomized to take simvastatin and niacin (S-N), antioxidants (vitamins E and C, beta-carotene, and selenium), S-N plus antioxidants (S-N+A), or placebo. Mean baseline plasma cholesterol, triglyceride, LDL-C, and HDL-C levels of the 153 subjects were 196, 207, 127, and 32 mg/dL, respectively. Without S-N, lipid changes were minor. The S-N and S-N+A groups had comparably significant reductions (P</=0.001) in plasma cholesterol, triglyceride, and LDL-C. However, increases in HDL-C, especially HDL(2)-C, were consistently higher in the S-N group than in the S-N+A group (25% vs 18% and 42% vs 0%, respectively). With S-N, but not with S-N+A, there was a selective increase in apolipoprotein (apo) A-I (64%) in HDL particles containing apo A-I but not A-II [Lp(A-I)] and their particle size. Thus, in CAD patients with low HDL-C, S-N substantially increased HDL(2)-C, Lp(A-I), and HDL particle size. These favorable responses were blunted by the antioxidants used owing to a striking selective effect on Lp(A-I). This unexpected adverse interaction between antioxidants and lipid therapy may have important implications for the management of CAD.

Electron-beam tomography coronary calcium scores are superior to Framingham risk variables for predicting the measured proximal stenosis burden

Previous studies of electron-beam tomography (EBT) have correlated coronary calcium scores with simplistic visual estimates of disease severity. In a clinical trial designed to evaluate 2 treatment strategies in coronary artery disease (CAD) patients with low levels of high-density lipoprotein cholesterol, we used quantitative coronary angiography to measure composite proximal stenosis burden from the baseline coronary angiogram and assessed the traditional Framingham risk variables in 146 patients. Stenosis burden is the sum, per patient, of percent stenosis for the worst lesion found in each of 9 standard proximal coronary segments. EBT estimates of coronary calcium (Agatston score, calcium volume score) were obtained for 115 of these patients. Stenosis burden was correlated with the calcium scores and risk variables. The best traditional correlates of stenosis burden were smoking status (r = 0.31, p = 0.001), prior myocardial infarction (r = 0.24, p = 0.005), body mass index (r = 0.23, p = 0.005), pack-years smoking (r = 0.20, p = 0.05), and age (r = 0.17, p = 0.04). With adjustment for age, all these correlations improved (eg, body mass index x age [r = 0.28, p = 0.001]). In addition, total cholesterol x age (r = 0.22, p = 0.008), fibrinogen x age (r = 0.19, p = 0.03), and systolic blood pressure x age (r = 0.18, p = 0.03) became significant correlates. Spearman correlations of the calcium scores with stenosis burden were considerably greater (Agatston: r = 0.62, p <0.0001; calcium volume: r = 0.63, p <0.0001). In multivariate regression analysis, calcium score, body mass index, and history of myocardial infarction were independent correlates of stenosis burden (R(2) = 0.45). At a given point in time, the EBT coronary calcium scores are greatly superior to the Framingham risk factors in predicting the measured proximal stenosis burden. Agatston and calcium volume scores are comparably predictive of stenosis burden.

Ca(2+)-dependent inhibition of actin-activated myosin ATPase activity by S100C (S100A11), a novel member of the S100 protein family

S100C (S100A11, calgizzarin) inhibits the actin-activated myosin Mg(2+)-ATPase activity of smooth muscle in a dose-dependent manner: its half-maximal effect occurs at a S100C/actin molar ratio of 0.05 and its maximal effect occurs at a ratio of 0.20. Furthermore, S100C was found to bind to actin with a stoichiometry of 1:6-7 in the presence of Ca(2+), with an affinity of 1 x 10(-6) M determined by cosedimentation assays. Other Ca(2+)-binding proteins such as S100A1, S100A2, S100B, and calmodulin did not inhibit actin-activated myosin Mg(2+)-ATPase activity. Calmodulin, S100A1, and S100B reversed the inhibitory effect of calponin in a Ca(2+)-dependent manner, S100A2 had no effect, and S100C had additional inhibitory effects. The results suggest that S100C might be involved in the regulation of actin-activated myosin Mg(2+)-ATPase activity through its Ca(2+)-dependent interaction with actin filaments.

Intracoronary thrombus and platelet glycoprotein IIb/IIIa receptor blockade with tirofiban in unstable angina or non-Q-wave myocardial infarction. Angiographic results from the PRISM-PLUS trial (Platelet receptor inhibition for ischemic syndrome management in patients limited by unstable signs and symptoms). PRISM-PLUS Investigators

BACKGROUND

The present study describes the effects of tirofiban, a nonpeptide platelet glycoprotein (GP) IIb/IIIa receptor blocker, on the characteristics of culprit lesions in patients with unstable angina (UA) or non-Q-wave myocardial infarction (NQWMI).

METHODS AND RESULTS

Of 1915 patients enrolled in PRISM-PLUS, 1491 had a readable film obtained a median of 65 hours after randomization. A core laboratory examined the culprit lesions for intracoronary thrombus burden (primary end point) and for TIMI flow grade distribution and severity of the obstruction and of underlying coronary artery disease (secondary end points). The combination of tirofiban plus heparin compared with heparin alone significantly reduced the intracoronary thrombus burden of the culprit lesions (OR=0.77, P=0.022), improved the perfusion grade (OR=0.65, P=0.002), and decreased the severity of the obstruction (P=0.037), but it did not influence the severity of the underlying plaque. Persistence of a thrombus in 45% of patients was associated with a 2.4-fold increase in the odds of death at 30 days (P=0.005) and a 2-fold increase in the odds of myocardial infarction (P=0.002).

CONCLUSIONS

The addition of tirofiban to heparin reduced the thrombus burden of the culprit lesion and improved distal perfusion in patients with UA or NQWMI, which supports the clinical benefit observed with the combination treatment.

Importance of endothelial function in mediating the benefits of lipid-lowering therapy

Trials of lipid lowering by various methods have clearly demonstrated the benefits, clinically and angiographically. Evidence of slowed arterial disease progression and even regression has been convincing but modest, at best. For example, among those treated intensively in the Familial Atherosclerosis Treatment Study (FATS), the mean improvement in proximal stenosis severity was <1% per patient, and only 12% of all lesions showed convincing regression. Despite these modest arterial benefits, the associated reductions in major cardiovascular events have been surprisingly great (24-35% in 3 recent large trials and > or =50% in angiographic trials using combination therapies). The process of plaque disruption helps explain this discrepancy. Disruption can be predicted by a large accumulation of core lipid in the plaque and a high density of lipid-laden macrophages in its thinned fibrous cap. Lesions with these characteristics comprise only 10-20% of the overall lesion population but account for 60-90% of the acute clinical events. Lipid-lowering therapy has beneficial effects on these "high-risk" features of plaque morphology. The composite of data presented here supports the hypothesis that lipid-lowering therapy selectively depletes lipids from this relatively small but dangerous subgroup of fatty lesions, effectively stabilizing them.