新疆地区酸马奶中酵母菌的鉴定及其生物多样性分析

从新疆少数民族牧民家庭采集的28份传统工艺酿造酸马奶样品中分离出87株酵母菌,并对其进行了生理生化鉴定、分子生物学鉴定和生物多样性分析。生化试验结果表明,新疆地区酸马奶中的酵母菌为Saccharomyces unisporus(占总分离株的48.3%),Kluyveromyces marxianus(27.6%),Pichia membranaefaciens(15.0%)和Saccharomyces cerevisiae(9.2%)。选取其中的6株酵母菌和1株参考菌株,进行大亚基(26S)rDNA D1/D2区域(600bp左右)碱基序列分析,并通过GenBank进行同源序列搜索以确定各菌株的归属,进一步验证生理生化方法的正确性。从得到的结果中可以看出,S.unisporus和K.marxianus为新疆地区酸马奶中的优势菌。     

Mathematical analysis of the global dynamics of a model for HTLV-I infection and ATL progression

Mathematical analysis is carried out that completely determines the global dynamics of a mathematical model for the transmission of human T-cell lymphotropic virus I (HTLV-I) infection and the development of adult T-cell leukemia (ATL). HTLV-I infection of healthy CD4(+) T cells takes place through cell-to-cell contact with infected T cells. The infected T cells can remain latent and harbor virus for several years before virus production occurs. Actively infected T cells can infect other T cells and can convert to ATL cells, whose growth is assumed to follow a classical logistic growth function. Our analysis establishes that the global dynamics of T cells are completely determined by a basic reproduction number R(0). If R(0)< or =1, infected T cells always die out. If R(0)>1, HTLV-I infection becomes chronic, and a unique endemic equilibrium is globally stable in the interior of the feasible region. We also show that the equilibrium level of ATL-cell proliferation is higher when the HTLV-I infection of T cells is chronic than when it is acute.     

The assessment of circulating 25(OH)D and 1,25(OH)2D: where we are and where we are going

The field of Vitamin D assay technology has progressed significantly over the past 4 decades. Further, the clinical utility of these measurements has moved from esoteric into mainstream clinical diagnosis. This movement has been fueled by the realization that Vitamin D is involved in bodily systems beyond skeletal integrity. The clinical assay techniques for circulating 25(OH)D and 1,25(OH)₂D have progressed away from competitive protein binding assay (CPBAs) that utilize tritium reporters to radioimmunoassay (RIAs) that utilize both I¹²⁵ and chemiluminescent reporters. These advances have allowed direct serum analysis of 25(OH)D in an automated format that provides a huge sample throughput. Detection of circulating 25(OH)D can also be achieved utilizing direct high-performance liquid chromatographic (HPLC) or liquid chromatography coupled with mass spectrometry (LC–MS) techniques. These methods are accurate, however, they require expensive equipment and restrict sample throughput in the large clinical laboratory. Direct serum detection of 1,25(OH)₂D is unlikely to occur for many reasons as a sample pre-purification will always be required. However, a semi-automated chemiluminescent detection system with automated sample preparation is in final development for the determination of circulating 1,25(OH)₂D. These advances will allow both 25(OH)D and 1,25(OH)₂D to be detected in an accurate, rapid fashion to meet the clinical demands we see emerging.     

The assessment of circulating 25(OH)D and 1,25(OH)2D: Where we are and where we are going

The field of Vitamin D assay technology has progressed significantly over the past 4 decades. Further, the clinical utility of these measurements has moved from esoteric into mainstream clinical diagnosis. This movement has been fueled by the realization that Vitamin D is involved in bodily systems beyond skeletal integrity. The clinical assay techniques for circulating 25(OH)D and 1,25(OH)₂D have progressed away from competitive protein binding assay (CPBAs) that utilize tritium reporters to radioimmunoassay (RIAs) that utilize both I¹²⁵ and chemiluminescent reporters. These advances have allowed direct serum analysis of 25(OH)D in an automated format that provides a huge sample throughput. Detection of circulating 25(OH)D can also be achieved utilizing direct high-performance liquid chromatographic (HPLC) or liquid chromatography coupled with mass spectrometry (LC–MS) techniques. These methods are accurate, however, they require expensive equipment and restrict sample throughput in the large clinical laboratory. Direct serum detection of 1,25(OH)₂D is unlikely to occur for many reasons as a sample pre-purification will always be required. However, a semi-automated chemiluminescent detection system with automated sample preparation is in final development for the determination of circulating 1,25(OH)₂D. These advances will allow both 25(OH)D and 1,25(OH)₂D to be detected in an accurate, rapid fashion to meet the clinical demands we see emerging.     

Twice single doses of 100,000 IU of vitamin D in winter is adequate and safe for prevention of vitamin D deficiency in healthy children from Ushuaia, Tierra Del Fuego, Argentina

In order to improve vitamin D status of children from Ushuaia (55°S), at the South of Argentina, double supplementation with 100.000 IU of vitamin D was administered at the beginning of winter (March 2004), and 3 months later during winter (June 2004). In 2004, serum 25-hydroxyvitamin D (25OHD) was measured before the first supplementation, a month after, and 3 months after receiving the second supplementation (March, April and September). We studied 18 healthy children from Ushuaia, age (mean ± S.D.) 7.3 ± 4.4 years old (range 1.2–14.6), seven girls and 11 boys. Before treatment, serum 25OHD was 29.3 ± 5.9 ng/ml. It increased significantly 1 month after the first supplementation (April): 35.3 ± 4.4 ng/ml (p < 0.001), and decreased significantly 3 months after the second supplementation: 22.4 ± 4.6 ng/ml (September (p < 0.001). No child was neither deficient (<10 ng/ml) nor insufficient (10–15 ng/ml) of vitamin D. On April, a month after the first supplementation, no children had vitamin D intoxication levels (>50 ng/ml). These results disclosed that to prevent vitamin D deficiency for children at zones of risk at the south of our country, double supplementation of 100,000 IU of vitamin D during autumn and winter, would be adequate and safe.     

Theory of optical spectra of photosystem II reaction centers: location of the triplet state and the identity of the primary electron donor

Based on the structural analysis of photosystem II of Thermosynechococcus elongatus, a detailed calculation of optical properties of reaction-center (D1-D2) complexes is presented applying a theory developed previously. The calculations of absorption, linear dichroism, circular dichroism, fluorescence spectra, all at 6 K, and the temperature-dependence of the absorption spectrum are used to extract the local optical transition energies of the reaction-center pigments, the so-called site energies, from experimental data. The site energies are verified by calculations and comparison with seven additional independent experiments. Exciton relaxation and primary electron transfer in the reaction center are studied using the site energies. The calculations are used to interpret transient optical data. Evidence is provided for the accessory chlorophyll of the D1-branch as being the primary electron donor and the location of the triplet state at low temperatures.     

Estimation of effective vaccination rate: pertussis in New Zealand as a case study

In some cases vaccination is unreliable. For example vaccination against pertussis has comparatively high level of primary and secondary failures. To evaluate efficiency of vaccination we introduce the idea of effective vaccination rate and suggest an approach to estimate it. We consider pertussis in New Zealand as a case study. The results indicate that the level of immunity failure for pertussis is considerably higher than was anticipated.     

A sensitive procedure for determination of cathepsin D: activity in alveolar and peritoneal macrophages

Summary Several new synthetic substrates fulfilling the specificity requirements of cathepsin D were synthesized. One of these D-Phe-Ser(O-CH₂-C₆H₅)-Phe-Phe-Ala-Ala-pAB (pAB = p-aminobenzoate) proved to be highly sensitive and convenient for measuring activity. Enzyme determination was carried out in a two-step reaction. In the first step the enzyme hydrolyzes the Phe-Phe bond of the substrate at pH 3.4. In the second step aminopeptidase M (EC 3.4.11.2) degrades one of the products Phe-Ala-Ala-pAB at pH 7 to 8 with the release of free pAB, which is then determined by a diazotization procedure. Activity can be measured in as little as 1 to 5 µg of macrophage protein. The activity of cathepsin D in rat alveolar macrophages was almost ten times higher than in resident peritoneal macrophages, and more than 25 times higher than in blood monocytes. The data indicate that transformation of blood monocytes into macrophages is associated with a much greater increase of cathepsin D activity in alveolar than peritoneal macrophages.Abbreviations BOC tert-butoxycarbonyl - H₄-furan tetrahydrofuran - DMF dimethylformamide - HPLC high pressure liquid chromatography - pNA p-nitroanilide - pAB p-aminobenzoate - -CH₂C₆H₅ benzyl - Bz benzoyl - Et₃N triethylamine - CF₃CO₂II trifluoroacetic acid     

Synthesis and antiproliferative activity of conjugates of adenosine with muramyl dipeptide and nor-muramyl dipeptide derivatives

We synthesized a series of MDP(D,D) and nor-MDP(D,D) derivatives conjugated with adenosine through a spacer as potential immunosuppressants. New conjugates 8a–k were evaluated on two leukemia cell lines (Jurkat and L1210) and PBMC from healthy donors. The conjugates 8a–k and MDP(D,D)/nor-MDP(D,D) derivatives 7e, f, i, j were active against L1210 cell line. Unconjugated nor-MDP(D,D) had better antiproliferative properties, but the conjugates 8b, f, g had the highest values of selectivity index. Both cell lines as well as PBMC were resistant to analogs 11a, b with the 6-aminohexanoic linker.     

Circulating vitamin D3 and 25-hydroxyvitamin D in humans: An important tool to define adequate nutritional vitamin D status

Circulating 25-hydroxyvitamin D [25(OH)D] is generally considered the means by which we define nutritional vitamin D status. There is much debate, however, with respect to what a healthy minimum level of circulation 25(OH)D should be. Recent data using various biomarkers such as intact parathyroid hormone (PTH), intestinal calcium absorption, and skeletal density measurements suggest this minimum level to be 80 nmol (32 ng/mL). Surprisingly, the relationship between circulating vitamin D₃ and its metabolic product—25(OH)D₃ has not been studied. We investigated this relationship in two separate populations: the first, individuals from Hawaii who received significant sun exposure; the second, subjects from a lactation study who received up to 6400 IU vitamin D₃/day for 6 months.Results (1) the relationship between circulating vitamin D₃ and 25(OH)D in both groups was not linear, but appeared saturable and controlled; (2) optimal nutritional vitamin D status appeared to occur when molar ratios of circulating vitamin D₃ and 25(OH)D exceeded 0.3; at this point, the V_max of the 25-hydroxylase appeared to be achieved. This was achieved when circulating 25(OH)D exceeded 100 nmol.We hypothesize that as humans live today, the 25-hydroxylase operates well below its V_max because of chronic substrate deficiency, namely vitamin D₃. When humans are sun (or dietary) replete, the vitamin D endocrine system will function in a fashion as do these other steroid synthetic pathways, not limited by substrate. Thus, the relationship between circulating vitamin D and 25(OH)D may represent what “normal” vitamin D status should be.     

Analysis of a competitive prey–predator system with a prey refuge

Gauss's competitive exclusive principle states that two competing species having analogous environment cannot usually occupy the same space at a time but in order to exploit their common environment in a different manner, they can co-exist only when they are active in different times. On the other hand, several studies on predators in various natural and laboratory situations have shown that competitive coexistence can result from predation in a way by resisting any one prey species from becoming sufficiently abundant to outcompete other species such that the predator makes the coexistence possible. It has also been shown that the use of refuges by a fraction of the prey population exerts a stabilizing effect in the interacting population dynamics. Further, the field surveys in the Sundarban mangrove ecosystem reveal that two detritivorous fishes, viz. Liza parsia and Liza tade (prey population) coexist in nature with the presence of the predator fish population, viz. Lates calcarifer by using refuges.     

Vitamin D in foods and as supplements

Numerous studies have shown that the vitamin D status is far from optimal in many countries all over the world. The main reason for this is lack of sunshine. Only a limited number of foods naturally contain vitamin D. Good sources of vitamin D(3) are fish (not only fatty fish), egg yolk, and offal such as liver. Some foods such as milk are fortified with vitamin D in some countries. Dietary vitamin D intake is low in many countries, especially as the dietary sources are limited. The use of supplements is important and seems to be high in some countries. Current dietary intake recommendations are too low to preserve/reach optimal S-25-OHD concentrations, when UVB radiation is not available. We suggest that the recommendations should be increased to at least 10 microg per day in all age groups when solar UVB is scarce. The elderly may need a daily vitamin D intake of 25 microg. If dietary intake of vitamin D is to be increased, food habits will have to change. From a public health point of view it is better to increase the potential sources of vitamin D by fortifying specific products that are consumed commonly in a whole population, or if necessary by especially vulnerable groups. Supplement use is probably the right alternative for vulnerable groups such as infants and inactive elderly in whom this is more easily implemented.     

Circulating vitamin D3 and 25-hydroxyvitamin D in humans: An important tool to define adequate nutritional vitamin D status

Circulating 25-hydroxyvitamin D [25(OH)D] is generally considered the means by which we define nutritional vitamin D status. There is much debate, however, with respect to what a healthy minimum level of circulation 25(OH)D should be. Recent data using various biomarkers such as intact parathyroid hormone (PTH), intestinal calcium absorption, and skeletal density measurements suggest this minimum level to be 80 nmol (32 ng/mL). Surprisingly, the relationship between circulating vitamin D₃ and its metabolic product—25(OH)D₃ has not been studied. We investigated this relationship in two separate populations: the first, individuals from Hawaii who received significant sun exposure; the second, subjects from a lactation study who received up to 6400 IU vitamin D₃/day for 6 months.

Results (1) the relationship between circulating vitamin D₃ and 25(OH)D in both groups was not linear, but appeared saturable and controlled; (2) optimal nutritional vitamin D status appeared to occur when molar ratios of circulating vitamin D₃ and 25(OH)D exceeded 0.3; at this point, the V_max of the 25-hydroxylase appeared to be achieved. This was achieved when circulating 25(OH)D exceeded 100 nmol.

We hypothesize that as humans live today, the 25-hydroxylase operates well below its V_max because of chronic substrate deficiency, namely vitamin D₃. When humans are sun (or dietary) replete, the vitamin D endocrine system will function in a fashion as do these other steroid synthetic pathways, not limited by substrate. Thus, the relationship between circulating vitamin D and 25(OH)D may represent what “normal” vitamin D status should be.     

Type II functional response for continuous, physiologically structured models

The goal of this work is to formulate a general Holling-type functional, or behavioral, response for continuous physiologically structured populations, where both the predator and the prey have physiological densities and certain rules apply to their interactions. The physiological variable can be, for example, a development stage, weight, age, or a characteristic length. The model leads to a Fredholm integral equation for the functional response, and, when inserted into population balance laws, it produces a coupled system of partial differential-integral equations for the two species, with a nonlocal integral term that arises from rules of interaction in the functional response. The general model is, typically, analytically intractable, but specialization to a structured prey-unstructured predator model leads to some analytic results that reveal interesting and unexpected dynamics caused by the presence of size-dependent handling times in the functional response. In this case, steady-states are shown to exist over long times, similar to the stable age-structure solutions for the McKendick-von Foerster model with exponential growth rates determined by the Euler-Lotka equation. But, for type II responses, there are early transient oscillations in the number of births that bifurcate in a few generations into either the decaying or growing steady-state. The bifurcation parameter is the initial level of prey. This special case is applied to a problem of the biological control of a structured pest population (e.g., aphids) by a predator (e.g., lady beetles).     

Functional Differentiation of Multiple Dopamine D1-Like Receptors by NNC 01-0012

Abstract: Although members of the multiple vertebrate/mammalian dopamine D1 receptor gene family can be selectively classified on the basis of their molecular/phylogenetic, structural, and tissue distribution profiles, no subtype-specific discriminating agents have yet been identified that can functionally differentiate these receptors. To define distinct pharmacological/functional attributes of multiple D1-like receptors, we analyzed the ligand binding profiles, affinity, and functional activity of 12 novel NNC compounds at mammalian/vertebrate D1/D1A and D5/D1B, as well as vertebrate D1C/D1D, dopamine receptors transiently expressed in COS-7 cells. Of all the compounds tested, only NNC 01-0012 displayed preferential selectivity for vertebrate D1C receptors, inhibiting [³H]SCH-23390 binding with an estimated affinity (∼0.6 n M ) 20-fold higher than either mammalian/vertebrate D1/D1A or D5/D1B receptors or the D1D receptor. Functionally, NNC 01-0012 is a potent antagonist at D1C receptors, inhibiting to basal levels dopamine (10 µ M )-stimulated adenylyl cyclase activity. In contrast, NNC 01-0012 (10 µ M ) exhibits weak antagonist activity at D1A receptors, inhibiting only 60% of maximal cyclic AMP production by dopamine, while acting as a partial agonist at vertebrate D1B and D1D receptors, stimulating adenylyl cyclase activity by ∼33% relative to the full agonist dopamine (10 µ M ), an effect that was blocked by the selective D1 receptor antagonist NNC 22-0010. These data clearly suggest that the benzazepine NNC 01-0012, despite lacking the N -methyl residue in the R3 position, is a selective and potent D1C receptor antagonist. Moreover, the differential signal transduction properties exhibited by NNC 01-0012 at these receptor subtypes provide further evidence, at least in vertebrates, for the classification of the D1C receptor as a distinct D1 receptor subtype.     

道地药材霍山石斛及其相似种的分子鉴定

为检测霍山石斛与霍山产铜皮石斛、霍山产铁皮石斛及其它产地的几种药用石斛的差异,对霍山石斛及其相似种进行ISSR分子标记比较研究。结果表明,尽管霍山石斛及其相似种的外部形态差异较小,但在ISSR分子标记指纹图谱上却存在着显著而稳定的差异。因此,根据ISSR分子标记指纹图谱所显示的多态性位点差异,能准确鉴别霍山石斛及其相似种植物及药材。此方法简单、稳定性高、可重复性好,在霍山石斛的分子鉴定研究中有较大的应用价值。     

补充维生素D对小鼠发育行为的影响研究

目的:本研究通过对子代小鼠维生素D的干预,探讨维生素D对子代小鼠行为的重要影响,为孕期补充维生素D提供理论依据。方法:建立孕鼠维生素D缺乏的实验模型。将子代小鼠分为三组:肌注维生素D的低剂量饮食组(a组,补充组)、肌注生理盐水的低剂量饮食组(b组,缺乏组)和正常饮食组(c组)。在第24天和第60天时,采用旷场实验、Morris水迷宫实验、社交试验对子代小鼠的行为进行监测。结果:孕期维生素D缺乏对子代小鼠的维生素D水平有显著的影响,子代小鼠出生10天时血清维生素D的浓度分别为:低剂量饮食组12.98±0.65μg/L,正常饮食组35.38±1.13μg/L,两组浓度值差异显著(P0.05)。旷场实验中,第24天时,缺乏组子代小鼠的运动总路程为1044±89.21 cm,显著少于补充组(1701.56±150.5 cm)和正常组(1755±154.2 cm),而其在中央区停留的时间为34.84±3.54 s,显著高于补充组(21.36±3.05 s)和正常组(21.77±3.64 s),其在周边停留的时间为265.2±3.54 s,显著少于补充组(278.6±3.05 s)和正常组(278.2±3.64 s);第60天时缺乏组子代小鼠在中央区停留的时间为28.79±3.68 s,显著高于补充组(17.21±2.59 s)和正常组(18.37±1.99 s),其在周边停留的时间为271.2±3.68 s,显著少于补充组(282.7±2.54 s)和正常组(281.6±1.99 s)。缺乏组在第60天时行动总路程为1653±141 cm低于其他两组,但差异不显著。Morris水迷宫实验中,三组子代小鼠第24天的穿越次数均显著高于第60天,呈现先增加后降低的趋势,而缺乏组的降低趋势更为明显。平台停留时间方面,三组子代小鼠在第60天均多于第24天,呈增加趋势。社交实验中,第24天时三组小鼠探索空笼子的时间没有明显差异,但缺乏组小鼠与代表新伙伴的陌生鼠1接触的时间低于与空笼子的接触时间,而正常组和补充组小鼠与陌生鼠接触的时间明显多于空笼子。第60天时三组小鼠探索空笼子的时间也没有明显差异,虽然缺乏组小鼠与陌生鼠的接触时间略高于与空笼子的接触时间,但差异不显著,而正常组和补充组小鼠与陌生鼠接触的时间仍明显多于空笼子。结论:向维生素D缺乏的子代小鼠补充维生素D能够对子代小鼠的兴奋性、空间认知能力、学习记忆能力和社交行为产生良性影响,在发育早期进行维生素D补充具有重要的预防作用。     

Synthesis and dopamine receptor pharmacological evaluations on ring C ortho halogenated 1-phenylbenzazepines

A series of 1-phenylbenzazepines containing bromine or chlorine substituents at the ortho position of the appended phenyl ring (2′-monosubstituted or 2′,6′- disubstituted patterns) were synthesized and evaluated for affinity towards dopamine D₁R, D₂R and D₅R. As is typical of the 1-phenylbenzazepine scaffold, the compounds displayed selectivity towards D₁R and D₅R; analogs generally lacked affinity for D₂R. Interestingly, 2′,6′-dichloro substituted analogs showed modest D₅R versus D₁R selectivity whereas this selectivity was reversed in compounds with a 2′-halo substitution pattern. Compound 10a was identified as a D₁R antagonist (K_i = 14 nM; IC₅₀ = 9.4 nM).     

The catalytically inactive precursor of cathepsin D induces apoptosis in human fibroblasts and HeLa cells

In several reports cathepsin D has been implicated in apoptosis. In some systems the effects of agents considered to be mediated by cathepsin D were inhibited in the presence of pepstatin A, an inhibitor of the enzyme. In other studies the effect of a mutant cathepsin D deprived of activity was indistinguishable from that of the normal enzyme. Here we show that in human fibroblasts and in HeLa cells apoptosis can be induced by microinjecting into cytosol either mature cathepsin D or its inactive precursor procathepsin D. The microinjected precursor remains in the uncleaved form. These results confirm that the proapoptotic effect of cathepsin D in the cytosol is independent of its catalytic activity and suggest that the interaction of cathepsin D with the downstream effector does not involve the active site of the enzyme, since in the proenzyme the active site is masked by the prosequence.