Changes in the angle-force curve of human elbow flexors following eccentric and isometric exercise

The aim of this study was to explore and compare the magnitude and time-course of the shift in the angle-force curves obtained from maximal voluntary contractions of the elbow flexors, both before and 4 consecutive days after eccentric and isometric exercise. The maximal isometric force of the elbow flexors of fourteen young male volunteers was measured at five different elbow angles between 50° and 160°. Subjects were then divided into two groups: the eccentric group (ECC, n=7) and the isometric group (ISO, n=7). Subjects in the ECC group performed 50 maximal voluntary eccentric contractions of the elbow flexors on an isokinetic dynamometer (30°^.s^–1), while subjects in the ISO group performed 50 maximal voluntary isometric muscle contractions with the elbow flexors at a lengthened position. Following the ECC and ISO exercise protocols, maximal isometric force at the five angles, muscle soreness, and the relaxed (RANG) and flexed (FANG) elbow angles were measured at 24 h intervals for 4 days. All results were presented as the mean and standard error, and a quadratic curve was used to model the maximal isometric force data obtained at the five elbow angles. This approach not only allowed us to mathematically describe the angle-force curves and estimate the peak force and optimum angle for peak force generation, but also enabled us to statistically compare the shift of the angle-force curves between and within groups. A large and persistent shift of the angle-force curve towards longer muscle lengths was observed 1 day after eccentric exercise (P<0.01). This resulted in a ~16° shift of the optimum angle for force generation, which remained unchanged for the whole observation period. A smaller but also persistent shift of the angle-force curve was seen after isometric exercise at long muscle length (P<0.05; shift in optimum angle ~5°). ECC exercise caused more muscle damage than ISO exercise, as indicated by the greater changes in RANG and ratings of muscle soreness (P<0.05). It was suggested that the shift in the angle-force curve was proportional to the degree of muscle damage and may be explained by the presence of overstretched sarcomeres that increased in series compliance of the muscle.     

A common Ile796Val polymorphism of the human SREBP cleavage-activating protein (SCAP) gene

We identified a new common amino acid polymorphism of isoleucine/valine at codon 796 in exon 16 of the gene for human sterol regulatory element binding protein (SREBP) cleavage-activating protein (SCAP), a central regulator of lipid synthesis and metabolism in animal cells. It can be detected as an MslI restriction fragment length polymorphism. The allelic frequencies were: isoleucine (A) allele, 0.57 and valine (G) allele, 0.43. This polymorphism may be useful for genetic studies of disorders affecting intracellular lipid metabolism and hyperlipidemia. Received: August 17, 1999 / Accepted: August 19, 1999     

丙型肝炎病毒基因分型及其与干扰素治疗应答的关系

目的为了解山西省丙型肝炎病毒的基因型和基因型对干扰素疗效的预示价值。方法用ＨＣＶ５’ＮＣ区酶切分型方法对９４例丙型肝炎病人进行基因分型，并观察其中４５例患者对干扰素α１ｂ治疗的应答。结果显示ＨＣＶⅠ组（Ⅰ、Ⅱ型）感染８０例（８５１％），ＨＣＶⅡ组（Ⅲ、Ⅳ型）感染１２例（１２８％），ＨＣＶⅠ／Ⅱ组混合感染２例（２１％）。在接受干扰素治疗的病例中，ＨＣＶⅠ组感染（３５例）的应答率为３７１％，持续应答率为１７１％，而Ⅱ组感染（１０例）的应答率为８０％，持续应答率为６０％，两组相比，有显著性差异（Ｐ＜００５，Ｐ＜００２５）。结论表明山西省以ＨＣＶⅠ组感染为主，干扰素对ＨＣＶⅡ组感染的疗效优于ＨＣＶⅠ组感染，ＨＣＶ基因型有预测干扰素疗效的意义。     

Stature estimation based on hand length and foot length

This study was carried out to estimate the relationship between hand length, foot length and stature using multiple linear regression analyses based on a sample of male and female adult Turks residing in Adana. Measurements of hand length, foot length and stature were taken from 155 adult Turks (80 male, 75 female) aged 17-23 years. The participants were students of the Medical Faculty of Cukurova University. A multiple linear regression model was fitted to the observed data. Stature was taken as the response or dependent variable, hand length and foot length were taken as explanatory variables or regressors. All possible (simple and multiple) linear regression models for each of males, females and both genders together were tested for the best model. The multiple linear regression model for both genders together was found to be the best model with the highest values for the coefficients of determination R2 = 0.861 and R2adjusted = 0.859, and multiple correlation coefficient R = 0.928.     

Length and moment arm of human leg muscles as a function of knee and hip-joint angles

Summary Lengths of muscle tendon complexes of the quadriceps femoris muscle and some of its heads, biceps femoris and gastrocnemius muscles, were measured for six limbs of human cadavers as a function of knee and hip-joint angles. Length-angle curves were fitted using second degree polynomials. Using these polynomials the relationships between knee and hip-joint angles and moment arms were calculated. The effect of changing the hip angle on the biceps femoris muscle length is much larger than that of changing the knee angle. For the rectus femoris muscle the reverse was found. The moment arm of the biceps femoris muscle was found to remain constant throughout the whole range of knee flexion as was the case for the medial part of the vastus medialis muscle. Changes in the length of the lateral part of the vastus medialis muscle as well as the medial part of the vastus lateralis muscle are very similar to those of vastus intermedius muscle to which they are adjacent, while those changes in the length of the medial part of the vastus medialis muscle and the lateral part of the vastus lateralis muscle, which are similar to each other, differ substantially from those of the vastus intermedius muscle. Application of the results to jumping showed that bi-articular rectus femoris and biceps femoris muscles, which are antagonists, both contract eccentrically early in the push off phase and concentrically in last part of this phase.     

应用长链RT-PCR法扩增我国登革2、4型病毒株全长cDNA

目的：采用长链RT-PCR技术扩增登革2型及4型病毒基因组全长cDNA，为构建登革病毒全长cDNA克隆、表达，深入阐明致病机理及探索新型疫苗奠定基础。方法：根据已测定的登革2、4型病毒全基因组序列，设计上下游引物。从感染登革病毒的乳鼠脑中提取病毒基因组RNA，采用长链RT-PCR技术进行扩增。为检验扩增产物的特异性，以PCR产物为模板扩增覆盖基因组的10个片段。将含有复杂二级结构的5′非编码区扩增片段，在377A型自动测序仪进行序列分析。结果：扩增出登革2、4型病毒基因组全长近11kb cDNA分子，非编码区测序结果表明扩增产物为登革2、4型病毒所特有。结论：利用长链RT-PCR首次成功扩增出登革病毒全长cDNA分子。     

Proliferation and telomere length in acutely mobilized blood mononuclear cells in HIV infected patients

The aim of the study was to investigate the mobilization of T cells in response to a stressful challenge (adrenalin stimulation), and to access T cells resided in the peripheral lymphoid organs in HIV infected patients. Seventeen patients and eight HIV seronegative controls received an adrenalin infusion for 1 h. Blood was sampled before, during and 1 h after adrenalin infusion. Proliferation and mean telomere restriction fragment length (telomeres) of blood mononuclear cells (BMNC) and purified CD8+ and CD4+ cells were investigated at all time points. In patients, the proliferation to pokeweed mitogens (PWM) was lower and decreased more during adrenalin infusion. After adrenalin infusion the proliferation to PWM was restored only in the controls. In all subjects telomeres in CD4+ cells declined during adrenalin infusion. Additionally, the patients had shortened telomeres in their CD8+ cells, and particularly HAART treated patients had shortened telomeres in all cell-subtypes. The finding that patients mobilized cells with an impaired proliferation to PWM during and after adrenalin infusion has possible clinical relevance for HIV infected patients during pathological stressful conditions, such as sepsis, surgery and burns. However, this study did not find a correlation between impaired proliferation and telomeres. It is concluded that physiological stress further aggravates the HIV-induced immune deficiency.     

Multipoint linkage mapping of the Xq25-q26 region in a family affected by the X-linked lymphoproliferative syndrome

We have performed, in a large Swiss family, a study of linkage between various DNA markers in the Xq24-27 region and the locus for the X-linked lymphoproliferative syndrome (XLP). Our results indicated that the marker DXS37 in Xq25-q26 is genetically linked to the XLP syndrome. The multipoint linkage analysis showed that the disease locus is distal to DXS11, but proximal to the hypoxanthine phosphoribosyl-transferase gene (HPRT).