Muscle Damage in Marathon Runners

In brief: Healthy people as well as highly trained athletes commonly experience delayed muscle soreness after severe exercise. Although many theories have been advanced, the pathophysiological basis for delayed muscle soreness is not known. The authors studied muscle biopsy samples from ten male runners immediately before and after a marathon and at one, three, five, and seven days after the marathon. Results showed muscle degeneration after training and after the marathon, and there was a significant inflammatory response throughout the week of recovery after the marathon. Therefore, the authors suggest that anyone experiencing postexercise delayed soreness is probably suffering from some degree of acute inflammation.     

Developmental profiles of infants with an <Emphasis Type="Italic">FMR1</Emphasis> premutation

Background

Emerging evidence suggests that a subset of FMR1 premutation carriers is at an increased risk for cognitive, emotional, and medical conditions. However, because the premutation is rarely diagnosed at birth, the early developmental trajectories of children with a premutation are not known.

Methods

This exploratory study examined the cognitive, communication, and social-behavioral profiles of 26 infants with a premutation who were identified through participation in a newborn screening for fragile X syndrome pilot study. In this study, families whose newborn screened positive for an FMR1 premutation were invited to participate in a longitudinal study of early development. Twenty-six infants with the premutation and 21 matched, screen-negative comparison babies were assessed using validated standardized measures at 6-month intervals starting as young as 3 months of age. The babies were assessed up to seven times over a 4-year period.

Results

The premutation group was not statistically different from the comparison group on measures of cognitive development, adaptive behavior, temperament, or overall communication. However, the babies with the premutation had a significantly different developmental trajectory on measures of nonverbal communication and hyperresponsivity to sensory experiences. They also were significantly more hyporesponsive at all ages than the comparison group. Cytosine-guanine-guanine repeat length was linearly associated with overall cognitive development.

Conclusions

These results suggest that infants with a premutation may present with subtle developmental differences as young as 12 months of age that may be early markers of later anxiety, social deficits, or other challenges thought to be experienced by a subset of carriers.

     

Granulocyte colony-stimulating factor receptors in human acute myelocytic leukemia

The binding of granulocyte colony-stimulating factor (G-CSF) to normal and human acute myeloid leukemia (AML) cells was investigated with radiolabeled recombinant human G-CSF (rhG-CSF). In all 14 cases of primary AML specific receptors for G-CSF were demonstrated on purified blast cells. The average numbers of G-CSF receptors ranged from very low to 428 receptors per cell (mean). Normal granulocytes showed G-CSF binding sites on their surface at higher densities (703 to 1,296 sites per cell). G-CSF receptors appeared to be of a single affinity type with a dissociation constant (kd) ranging between 214 and 378 pmol/L for AML blasts and 405 to 648 pmol/L for granulocytes. In 12 of 14 cases, including those with relatively low specific binding, G-CSF was a potent inducer of DNA synthesis of blasts in vitro; therefore, apparently relatively few receptors are required to permit activation of AML cell growth. However, in two cases cell cycling was not activated in response to G-CSF despite G-CSF receptor availability. The results show that G-CSF receptors of high affinity are frequently expressed on the blasts of human AML, but their presence may not be a strict indicator of the proliferative responsiveness of the cells to G- CSF.     

Critical role of CD28/B7 costimulation in the development of human Th2 cytokine-producing cells

CD28 is a major costimulatory signal receptor for T cells. We have used human naive CD4+ cells from cord blood to analyze the effect of the CD28/B7 costimulatory pathway on development of T helper (Th) subsets. We show that CD28 costimulation is critical for development of the Th2 cytokine-producing cells and that in the absence of CD28 costimulation, cells are not primed to produce Th2 cytokines and consequently "default" to the Th1 subset, independent of the presence of exogenous cytokines. After CD28 costimulation, cells differentiate into a subset that produces Th2 cytokines. However, further CD28 costimulation is not required to maintain Th2 cytokine production. We conclude that D28 costimulation is critical for the development of Th0 and Th2 subsets, but not for the maintenance of cytokine production.     

维A类化合物4-APR抑制肿瘤侵袭、转移的作用

用体内外实验模型,研究了新维A类化合物4-乙酰胺苯基维A酸酯(4-APR)对肿瘤侵袭、转移的抑制作用。4-APR 43.3mg·kg^-1po即能减少小鼠Lewis肺癌的自发性肺转移瘤数。半体内实验证明4-APR10^-5mol·L^-1和10^-6mol·L^-1对B16-F10癌细胞的人工肺转移瘤数分别抑制67.9%和36.6%。体外实验显示,4-APR对B16-F10细胞侵袭重组基底膜的抑制率分别为54.2%和41.9%。     

炎宁冲剂的抗炎与解热作用研究

目的：研究炎宁冲剂的抗炎与解热作用。方法：采用角叉菜胶致大鼠足跖炎性肿胀。二甲苯致小鼠耳毛细血管通透性增高,以及大鼠皮下羧甲基纤维素囊中白细胞出游等急性炎症模型研究炎宁冲剂的抗炎作用。采用啤酒酵母液引起家兔发热的方法研究炎宁冲剂的解热作用。结果：炎宁冲剂对以上实验动物均具有明显的抗炎和解热作用。结论：炎宁冲剂对急性炎症具有明显的抗炎作用。对啤酒酵母液引起家兔发热具有明显解热作用。     

Auditory evoked magnetic fields in adults with fragile X syndrome

Hyper-reactivity and anxiety to sensory stimuli have been described in patients with fragile X syndrome (FXS), and may be related to abnormal processing in afferent sensory pathways. We used magnetoencephalography (MEG) to measure auditory responses to pure tones in 11 adults with FXS and 11 non-FXS subjects. The amplitude for the N100m auditory evoked field component was significantly higher for patients with FXS than for subjects. FXS subjects also had less lateralized N100m anterior-posterior dipole locations. These data may suggest that more neurons are activated by acoustic stimuli in FXS, consistent with subjective experience of increased stimulus intensity. Anomalous cerebral lateralization may suggest an early critical window for effects on neocortical development of the fragile X mental retardation protein (FMRP) produced by the FMR1 gene in individuals with FXS.     

Sleeping position and sudden infant death syndrome (SIDS): effect of an intervention programme to avoid prone sleeping

The proportion of prone sleeping among sudden infant death syndrome (SIDS) victims and infants in general, and the rate of SIDS were prospectively studied in the county of Hordaland, Norway, three years before (1987–89) and three years after (1990–92) a campaign to discourage prone sleeping. Before the campaign, 64% of random reference infants were put prone versus 8% after (p < 0.0001). Concurrently, the rate of SIDS decreased from 3.5 to 1.6 per 1000 live births (63 infants before and 30 after the campaign, p = 0.0002). Prone sleeping was not considered a statistically significant risk factor for SIDS before (OR 2.0,95% CI 0.8–4.5), but was highly significant (OR 11.3,95% CI 3.6–36.5) after the campaign. Prone sleeping is an important risk factor for SIDS, but the association may be missed in epidemiological studies if prone is the predominant sleeping position. Behaviour with regard to sleeping position may be changed rapidly by means of a simple campaign.