Naturally occurring antibodies reactive with sperm proteins: apparent deficiency in AIDS sera

A set of naturally occurring immunoglobulin M (IgM) antibodies that are reactive with a defined subset of proteins in the acrosomal cap region of human sperm has been identified. These antibodies are present in a broad spectrum of human sera from males and females, 1 day to 40 years of age, and are absent or markedly deficient in a large proportion of sera from individuals with the acquired immune deficiency syndrome (AIDS) or at risk for AIDS. The subset of proteins with which the IgM antibodies are reactive includes a factor (or factors) capable of inhibiting lectin-induced T-lymphocyte proliferation. The prevalence of the sperm-reactive IgM antibodies indicates that they are not elicited by sperm. Further, immunoreactivity of the sperm proteins resulting in depletion of specific circulating IgM antibodies, or other interactions between the sperm proteins and elements of the immune system, may be a factor in the suppressed state of the immune system in AIDS.     

不同程度跛行奶牛血浆中E_2、GnRH、FSH和PGF2a的检测与分析

为研究跛行对产后奶牛主要生殖激素的影响,实验采用5分制跛行评价标准,在黑龙江地区某规模化牧场,对产后40 d泌乳牛(未使用任何生殖激素类药物)进行跛行评分,然后对跛行评分为1~5分奶牛血浆样品中的促性腺激素释放激素(Gn RH)、促卵泡生长激素(FSH)、雌二醇(E2)和前列腺素(PGF2a)含量进行测定,分析不同跛行评分奶牛血浆样品中4种激素的变化。共获得49头泌乳奶牛作为研究对象,其中1分为8头,2分为19头,3分为14头,4分为4头,5分为4头。研究结果显示,与健康奶牛相比,随着跛行评分的增加,E2、Gn RH、FSH和PGF2a的含量均呈现不同程度的减少趋势。研究结果提示,跛行能影响奶牛产后主要的生殖激素分泌。     

Synthetic competitive antagonists of corticotropin-releasing factor: effect on ACTH secretion in the rat

Polypeptide analogs of the known members of the corticotropin-releasing factor (CRF) family were synthesized and tested in vitro and in vivo for enhanced potency or competitive antagonism. Predictive methods and physicochemical measurements had suggested an internal secondary alpha-helical conformation spanning about 25 residues for at least three members of the CRF family. Maximization of alpha-helix-forming potential by amino acid substitutions from the native known sequences (rat/human and ovine CRF, sauvagine, and carp and sucker urotensin 1) led to the synthesis of an analog that was found to be more than twice as potent as either of the parent peptides in vitro. In contrast, certain amino-terminally shortened fragments, such as alpha-helical CRF or ovine CRF residues 8 to 41, 9 to 41, and 10 to 41, were found to be competitive inhibitors in vitro. Selected antagonists were examined and also found to be active in vivo.     

Motivated forgetting mediated by implicit verbal chaining: a laboratory analog of repression

After learning an A-B paired-associates list, college students read a list of D words, several of which were consistently accompanied by unavoidable electric shock. The D words were members of implicit B-C, C-D chains, inferred from published word-association norms. In a subsequent recall test of the original A-B list, the B words that were implicitly associated with the shocked D words were forgotten significantly more often than control words.     

腹腔镜下保守手术治疗不同类型子宫内膜异位症并发不孕患者疗效的对比研究

目的 探讨腹腔镜下保守手术治疗不同类型子宫内膜异位症(简称内异症)合并不孕患者的疗效。方法 选择因内异症合并不孕行腹腔镜保守性手术治疗的145例患者,术后随访1～5年,观察自然妊娠结局及复发情况。结果 深部浸润组术后GnRH-a用药情况分别与卵巢组和腹膜组比较,均差异有统计学意义(均P<0.05),而卵巢组与腹膜组比较,差异无统计学意义(P>0.05);三组累积妊娠率分别比较,均差异无统计学意义(P>0.05);深部浸润组、卵巢组、腹膜组三组患者术后妊娠距手术的间隔时间分别为(37.4±1.5)、(9.3±2.3)、(6.5±1.9)个月,深部浸润组与卵巢组及腹膜组比较,均延长(P<0.05);三组复发率比较,差异无统计学意义但P值较小(P=0.052)。结论 深部浸润型内异症患者手术后平均妊娠时间延长,但累积妊娠率与卵巢型和腹膜型内异症相似。     

Oxytocin: crystal data of a seleno analog

The sulfur atom in position 6 of deamino-oxytocin (1-beta-mercapto-propionic acid-oxytocin) was replaced by selenium. The crystals of the resulting deamino-6-seleno-oxytocin are similar to those of the "wet" form of deamino-oxytocin, but they are stable upon prolonged exposure to air.     

Erythropoietin: hypothesis of action tested by analog computer

The action of erythropoietin on the pool of undifferentiated bone marrow cells has been examined with the aid of a model tested with an analog computer. The model is consistent with reported experimental results. The essential aspects of the action are (i) the effect is exerted during the S phase of the cell's cycle; (ii) " effective " erythropoietin is present in the cell only during G(1) and part of S; and, (iii) hormone molecules survive in the cell for only a limited time in effective form and require a certain time to assume this form.     

Antigen competition: antigens compete for a cell occurring with limited frequency

Experimentally altered ability of transferred spleen cells to generate hemolytic plaque-forming cells provided evidence that antigens compete for a type of multipotential cell that contributes to the formation of immunologically competent units. De'ay of exposure of transferred spleen cells to antigen provided results which suggest that different types of cells interact to form competent, antigen-reactive units even in the absence of antigen.     

Stimulation of gonadotropin release by a non-GnRH peptide sequence of the GnRH precursor

The human gonadotropin-releasing hormone (GnRH) precursor comprises the GnRH sequence followed by an extension of 59 amino acids. Basic amino acid residues in the carboxyl terminal extension may represent sites of processing to biologically active peptides. A synthetic peptide comprising the first 13 amino acids (H X Asp-Ala-Glu-Asn-Leu-Ile-Asp-Ser-Phe-Gln-Glu-Ile-Val X OH) of the 59-amino acid peptide was found to stimulate the release of gonadotropic hormones from human and baboon anterior pituitary cells in culture. The peptide did not affect thyrotropin or prolactin secretion. A GnRH antagonist did not inhibit gonadotropin stimulation by the peptide, and the peptide did not compete with GnRH for GnRH pituitary receptors, indicating that the action of the peptide is independent of the GnRH receptor. The GnRH precursor contains two distinct peptide sequences capable of stimulating gonadotropin release from human and baboon pituitary cells.     

Discovery of a Jupiter/Saturn analog with gravitational microlensing

Searches for extrasolar planets have uncovered an astonishing diversity of planetary systems, yet the frequency of solar system analogs remains unknown. The gravitational microlensing planet search method is potentially sensitive to multiple-planet systems containing analogs of all the solar system planets except Mercury. We report the detection of a multiple-planet system with microlensing. We identify two planets with masses of approximately 0.71 and approximately 0.27 times the mass of Jupiter and orbital separations of approximately 2.3 and approximately 4.6 astronomical units orbiting a primary star of mass approximately 0.50 solar mass at a distance of approximately 1.5 kiloparsecs. This system resembles a scaled version of our solar system in that the mass ratio, separation ratio, and equilibrium temperatures of the planets are similar to those of Jupiter and Saturn. These planets could not have been detected with other techniques; their discovery from only six confirmed microlensing planet detections suggests that solar system analogs may be common.     

Pancreatic secretion by nonparallel exocytosis: potential resolution of a long controversy

The idea that pancreatic digestive enzyme secretion can occur in a nonparallel manner has been controversial because of its presumed incompatibility with the exocytosis secretory mechanism. Correlation and regression analysis of enzyme output by the rabbit pancreas after it is stimulated with cholecystokinin and chymodenin revealed that digestive enzymes are secreted in a highly linked fashion, compatible with exocytosis and with nonparallel secretion. Thus, exocytosis and nonparallel secretion are not contradictory processes, but rather nonparallel secretion is due to exocytosis from heterogeneous sources within the pancreas.     

芦荟内酯豆腐的研制

以芦荟和大豆为原料研制了芦荟内酯豆腐，其最佳工艺参数为：豆乳浓度1：7，GDL（D－葡萄糖酸－δ－内酯）添加量0.3%，芦荟汁添加量为豆乳的10％，在85℃下，加热40min得成品，该产品呈淡绿色，具纯正豆香味及芦荟特有香味，并具有保健和美容作用。     

Todorokites: a new family of naturally occurring manganese oxides

Todorokites are found in numerous terrestrial deposits and are important copper- and nickel-bearing materials in manganese nodules. Their structures are highly disordered, not well known, and controversial. High-resolution transmission electron microscopy reveals that terrestrial todorokites consist of tunnel structures of previously unreported dimensions and that these tunnel structures are intergrown coherently on a unit cell scale. Many types and degrees of disorder are evident in the high-resolution images. These newly discovered structures indicate a need for a revised nomenclature of tunnel manganese oxides, and such a system is suggested.     

Atomic structure of adenosine deaminase complexed with a transition-state analog: understanding catalysis and immunodeficiency mutations

The crystal structure of a murine adenosine deaminase complexed with 6-hydroxyl-1,6-dihydropurine ribonucleoside, a nearly ideal transition-state analog, has been determined and refined at 2.4 angstrom resolution. The structure is folded as an eight-stranded parallel alpha/beta barrel with a deep pocket at the beta-barrel COOH-terminal end wherein the inhibitor and a zinc are bound and completely sequestered. The presence of the zinc cofactor and the precise structure of the bound analog were not previously known. The 6R isomer of the analog is very tightly held in place by the coordination of the 6-hydroxyl to the zinc and the formation of nine hydrogen bonds. On the basis of the structure of the complex a stereoselective addition-elimination or SN2 mechanism of the enzyme is proposed with the zinc atom and the Glu and Asp residues playing key roles. A molecular explanation of a hereditary disease caused by several point mutations of an enzyme is also presented.     

Long-term synaptic changes produced by a cellular analog of classical conditioning in Aplysia

A change in synaptic strength arising from the activation of two neuronal pathways at approximately the same time is a form of associative plasticity and may underlie classical or Pavlovian conditioning. A cellular analog of a classical conditioning protocol produces short-term associative plasticity at the connections between sensory and motor neurons in Aplysia. A similar training protocol produced long-term (24-hour) enhancement of excitatory postsynaptic potentials (EPSPs). EPSPs produced by sensory neurons in which activity was paired with a reinforcing stimulus were significantly larger than unpaired controls 24 hours after training. Thus, associative plasticity at the sensory to motor neuron connection can occur in a long-term form in addition to the short-term form. In this system, it should be possible to analyze the molecular mechanisms underlying long-term associative plasticity and classical conditioning.     

Reduction of naturally occurring motoneuron death in vivo by a target-derived neurotrophic factor

Treatment of chick embryos in ovo with crude and partially purified extracts from embryonic hindlimbs (days 8 to 9) during the normal cell death period (days 5 to 10) rescues a significant number of motoneurons from degeneration. The survival activity of partially purified extract was dose-dependent and developmentally regulated. The survival of sensory, sympathetic, parasympathetic, and a population of cholinergic sympathetic preganglionic neurons was unaffected by treatment with hindlimb extract. The massive motoneuron death that occurs after early target (hindlimb) removal was partially ameliorated by daily treatment with the hindlimb extract. These results indicate that a target-derived neurotrophic factor is involved in the regulation of motoneuron survival in vivo.     

Immunization of Male Mice with a New Recombinant GnRH Fusion Protein Reduces the Testicular Function

The objective of the present study was to evaluate the effect of an immunogenic maltose-binding protein-gonadotropin releasing hormone （GnRH-6-MBP） using genetic engineering. The synthetic mammalian tandem repeated GnRH hexamer gene was inserted into the expression plasmid pMAL-c2x. Recombinant GnRH-6-MBP protein was over- expressed in E.coli strain BL21. Amylose resin with affinity chromatograph was used to purify target protein. The reactiongenicity of fusion protein was identified by indirect enzyme linked immunosorbent assay （ELISA）, and the antigenicity and biological effects of GnRH-6-MBP were tested in mice. In the experiment, 20 male Kunming white mice of 20 d old were randomly divided into treatment and control group. Ten mice were immunized with 100 μg GnRH-6-MBP administered subcutaneously （s.c.） thrice at 2-week intervals with GnRH-6-MBP. Mice were sacrificed after 3 weeks following the booster injection, the testis was removed, weighed and measured, and the histological structure was observed. The reactiongenicity of fusion protein to GnRH antibody was much higher than the control. Active immunization against GnRH-6-MBP reduced remarkably （P 〈 0.01） the length and weight of the testis, and shortened the girth and width of the testis （P 〈 0.05）, and suppressed testicular spermatogenesis compared to the control mice. These results indicate that the recombinant GnRH-6-MBP acted as a strong immunogen and caused atrophy of the testis.     

Chemical methylation of inorganic mercury with methylcobalamin, a vitamin B12 analog

Chemical methylation of mercuric chloride with methylcobalamin has been studied. Methylated mercury was detected by gas chromatography; and analysis of the products of the reaction by thin-layer chromatography revealed that the methylation proceeded at a remarkably high rate when methylcobalamin and inorganic mercury were mixed. Dimethylmercury was an initial product of the reaction.     

Major enhancement of the affinity of an enzyme for a transition-state analog by a single hydroxyl group

The compound 1,6-dihydropurine ribonucleoside, prepared by reduction of nebularine in the presence of ultraviolet light, is bound by adenosine deaminase approximately 10(8)-fold less tightly than 6-hydroxy-1,6-dihydropurine ribonucleoside, a nearly ideal transition-state analog. This difference in affinities, which is associated with the presence of a single hydroxyl group in the second compound, suggests the degree to which one or a few hydrogen bonds may stabilize the transition state in an enzyme reaction of this type.