Two-step hard acid deprotection/cleavage procedure for solid phase peptide synthesis

A new two-step deprotection/cleavage procedure for t-butoxycarbonyl (Boc) based solid phase peptide synthesis is reported. First the protective groups are removed from 4-(oxymethyl)-phenylacetamidomethyl (PAM) resin attached peptide with the weak hard acid, trimethylsilyl bromide-thioanisole/trifluoroacetic acid (TFA). In the second step, the peptide is cleaved from the resin with a stronger hard acid such as trimethylsilvl trifluoromethanesulfonate in TFA or with HF. The method is also shown to deformylate Nⁱⁿ-formyltryptophan moiety efficiently. The usefulness of this procedure for practical solid phase peptide synthesis is demonstrated by comparison with other deprotection methods in the synthesis of urotensin II and human endothelin.     

Co-localization of SCPB-like and FMRFamide-like immunoreactivities in crustacean nervous systems

A monoclonal antibody to the molluscan small cardioactive peptide SCPB and a polyclonal antibody to FMRFamide were used to localize antigens in the stomatogastric nervous system and brain of two species of Cancer. Both antibodies labeled cell bodies, axons, and neuropilar processes in the brain and in the stomatogastric nervous system. All of the SCPB immunoreactive neurons were co-labeled with antibody to FMRFamide. However, antibody to FMRFamide labeled additional neurons of the commissural ganglion and the brain that were not immunoreactive to the monoclonal SCPB antibody.     

再论妊娠期糖尿病与胎儿生长发育

目的 研究妊娠期糖尿病与胎儿生长发育中糖代谢特点的关系。方法 选择妊娠期糖尿病25例（GDM组），正常孕妇20例（对照组），分别测孕妇空腹血糖、糖耐量、C肽、IGF－I、新生儿出生2h内空腹血糖，并依据新生儿出生体重分为大于胎龄儿组（LGA组，≥4000g），适于胎龄儿组（AGA组，2500－3999g)。结果 C肽及新生儿出生2h内空腹血糖GDM组与对照组差异有显著性；糖耐量各时点血糖值餐后2h血糖值LGA和AGA组差异有显著性。结论 血糖始终是影响胎儿生长发育的重要因素，孕妇餐后2h血糖水平与巨大儿的发生呈正相关。     

Conformations of neurotensin in solution and in membrane environments studied by 2-D NMR spectroscopy

Two-dimensional HOHAHA and ROESY nuclear magnetic resonance techniques are used to obtain complete proton resonance assignments and to perform a conformational investigation of the neuropeptide neurotensin (pGlu-Leu-Tyr-Glu-Asn-Lys-Pro-Arg-Arg-Pro-Tyr-Ile-Leu) in aqueous solution, methanol, and membrane-mimetic [deuterated sodium dodecylsulfate (SDS)] environments. Results suggest the absence of discernible elements of secondary structure in water and methanol. ROESY spectra confirm that Lys-Pro and Arg-Pro peptide bonds are all-trans, but that a significant population of cis Arg-Pro bonds arises in aqueous solution, which increases in the environment of SDS micelles. The conformational ensemble of the peptide is observed to narrow as it becomes bound through its cationic mid-region to SDS micelles, with the accompanying advent of local extended structure. The overall results indicate the inherent conformational flexibility of neurotensin, and emphasize the environmental dependence of conformation in peptides of medium length.     

Suppression of experimental allergic encephalomyelitis by the encephalitogenic peptide, in solution or bound to liposomes

We have investigated the ability of liposome-bound encephalitogenic peptide to suppress experimental allergic encephalomyelitis (EAE) in the guinea pig. EAE was induced by challenge with the encephalitogenic peptide, residues 113-122 of human myelin basic protein (MBP) in complete Freund's adjuvant. The peptide was acylated with stearic acid in order to anchor it to the lipid bilayer. The liposomal-bound peptide effectively suppressed clinical signs of EAE at relatively low doses, when given subcutaneously or intraperitoneally without incomplete Freund's adjuvant, several days after challenge. In vitro proliferation of lymphocytes from treated, protected animals in response to the peptide was greatly decreased but that to the purified protein derivative of tuberculin antigen was not, indicating an antigen-specific effect. However, histological signs of EAE were not reduced. The free peptide in solution was somewhat less effective when given intraperitoneally but was as or nearly as effective as liposome-bound peptide when given subcutaneously. Binding to liposomes may decrease the rate of clearance or degradation of the peptide when given intraperitoneally.     

Plasma atrial natriuretic peptide (ANP) concentration and fluid balance during rapid intravenous saline infusions in camels

Human muscle samples were obtained with the percutaneous biopsy technique. The samples were membrane-hyperpermeabilized (skinned) using a chemical or freeze-drying technique. Short single fibre segments were dissected from the sample, transferred to an experimental chamber, connected to a force transducer and manipulator, and exposed to temperature-controlled solutions. The force generating-capacity, the sensitivity of the contractile apparatus to calcium and the caffeine threshold for calcium release from the sarcoplasmic reticulum could be studied in the short muscle fibre segments obtained from man with the percutaneous muscle biopsy technique. The average length of the fibre segments between the connectors was 0.44±0.21 mm. Thus, detailed studies of the contractile machinery can be made on human skinned muscle fibres with only minimal discomfort to the patient or subject during biopsy, which should be useful in studies of neuromuscular disease, muscle plasticity or in applied physiology.     

牛磺酸对高血压和血管活性物质的影响

在原发性高血压(EH)患者、大鼠腹主动脉狭窄和高盐摄入引起高血压模型上,观察到口服牛磺酸治疗4周后均明显降低平均动脉压和收缩压,42.2%的患者血压恢复正常,并能抑制EH患者和高血压大鼠血浆内皮素(ET)、血管紧张素II(AII)水平的升高,增加高血压大鼠血浆降钙素基因相关肽(CGRP)和主动脉组织中的牛磺酸含量.以上结果表明,牛磺酸在降压作用同时伴有缩血管物质的降低和舒血管物质的增加,为以牛磺酸作为降血压辅助药物提供了依据.     

体外培养新生大鼠心房壁中的CGRP-IR和NPY-IR神经细胞

对体外培养新生SD大鼠心房壁的神经细胞，按SternbergerPAP法进行了降钙素基因相关肽（CGRP）和神经肽Y（NPY）免疫细胞化学研究。结果显示：CGRP-IR阳性细胞数量较少，实验的5份标本只有2份见到阳性细胞，而NPY-IR阳性细胞在所有实验标本中均可见到。本研究在培养条件下证实心内神经节中有CGRP-IR阳性细胞存在，支持心脏有器官内感觉神经细胞的设想。同时对心内神经细胞的化学性质进行了讨论。     

Prostaglandins and CGRP release from cardiac sensory nerves

Summary (1) The possible influence of Prostaglandins (PG) E₁ and I₂ as well as ischaemia, ouabain and bradykinin on the outflow of calcitonin gene-related peptide (CGRP)- and neuropeptide Y (NPY)-like immunoreactivity (LI) from the guinea-pig heart was studied in vitro. (2) Exposure to PGE₁ (10^–5 M), but not PGI₂ (10^–5 M), induced an increased outflow, suggesting release of CGRP-LI. PGE₁ simultaneously increased the contractile force and heart rate while no effects were observed on perfusate volume or outflow of NPY-LI. PGI₂ had no effect on contractile parameters or coronary flow. In separate experiments on capsaicin-pretreated animals, the stimulatory effects of PGE₁ on heart rate and contractile force remained unchanged while no increased CGRP-LI outflow was detectable. (3) Ouabain, bradykinin and reperfusion after total stop-flow ischaemia was associated with an indomethacin-resistant increase in perfusate levels of CGRP-LI but not of NPY-LI. While ouabain markedly increased the contractile force, exposure to bradykinin or ischaemia did not induce any clear-cut changes in contractile force or heart rate. (4) Capsaicin-exposure evoked a markedly increased outflow of CGRP-LI but not of NPY-LI in combination with an increase in heart rate and a decrease in contractile force. Repeated administration of capsaicin induced tachyphylaxis. The stimulatory effects of capsaicin on CGRP-LI outflow and heart rate, but not the negative inotropic effect, did not occur in capsaicin-pretreated animals. (5) It is concluded that PGE₁, but not PGI₂, can activate cardiac capsaicin-sensitive fibres as revealed by increased outflow of CGRP-LI. The cardiostimulatory effects induced by PGE₁ are not related to CGRP release, however. A possible prostaglandin link in the CGRP-LI released by ouabain, bradykinin or ischaemia seems unlikely. Send offprint requests to: A. Franco-Cereceda at the above address