Influence of dietary protein level on protein self-selection and plasma and brain amino acid concentrations

Control of protein intake was studied in young rats that were allowed to choose between either protein-free and 55% casein diets or 15% and 55% casein diets. Animals on the protein-free vs. 55% casein regimen exhibited a lower weight gain, a lower cumulative energy intake and a greater cumulative total protein intake during the 13-day study compared to rats selecting between 15% and 55% casein. The daily average proportion of total food selected as casein by animals choosing between protein-free and 55% casein diets increased from 15% to 38% during the course of the study. In contrast, rats choosing between 15% and 55% casein chose 18-22% of total food as protein throughout the entire study. Long-term protein intake or protein selection did not correlate significantly with whole-brain contents of 5-HT or 5-HIAA. Our results suggest that protein intake is not regulated at a constant proportion of total calories, but is controlled between a minimum level that will support rapid growth and a maximum that, if exceeded, would require the animal to undergo substantial metabolic adaptation. The mechanism controlling protein selection may involve diet-induced changes in the brain content of total free indispensable amino acids.     

A portable device for the rapid concentration of viruses from large volumes of natural freshwater

A portable device for the rapid concentration of viruses from natural freshwaters described and its performance in field use is evaluated. The system handled up to 500 litres of water in less than 90 min at a cost of only 2 pounds per sample. Where the samples contained sufficient bacteriophages for detection by direct plating the apparent phage recoveries were greater than 75%. Plant and animal viruses were also concentrated from waters with this system.     

Study of the HLA system in Burkitt's lymphoma

Seventy-eight patients with Burkitt's lymphoma and seventy controls from Ghana were typed for HLA-A, B, C and DR antigens, to determine whether there is an association between the HLA system and Burkitt's lymphoma. Increased relative risk was observed in Burkitt's lymphoma patients with DR7, HLA-A1 and B12 (BW44).     

Determination of glucokinase and hexokinase activity in liver extracts previously purified on Molselect G-50 dextran gel

Hexokinase and glucokinase activity in the supernatant of a rabbit liver homogenate obtained at 18,000g was determined by a spectrophotometric method. Preliminary purification to remove low-molecular-weight components by gel filtration on Molselect G-50 dextran was shown to prevent reduction of NADP unconnected with the hexokinase reaction.Presented by Academician of the Academy of Medical Sciences of the USSR V. S. Il'in.Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 82, No. 7, pp. 891–892, July, 1976.     

Isolation and characterization of entomopox virions from virus-containing inclusions of Amsacta moorei (Lepidoptera: Arctiidae)

Preparations of Amsacta moorei entomopox virions were obtained from virus-containing inclusions (VCI) by using a carbonate-thioglycolate solution (pH 10.7–11.5). The virions possessed a uniform coat (“halo”) surrounding the viral envelope and exhibited an RNA polymerase activity. The “halo” could be removed by prolonged exposure to the carbonate-thioglycolate solution. Virions obtained by this treatment, however, possessed low infectivity and no detectable RNA polymerase activity. Removal of the “halo” by trypsin resulted in virions which possessed RNA polymerase activity and relatively high infectivity.Preparations of particles with and without the “halo” were similar in percent DNA, protein per OD₂₆₀, number of particles per OD₂₆₀, and RNA polymerase activity. Particles without the “halo,” however, were less dense (1.262 g/cm³) in CsCl than those with the “halo” (1.282 g/cm³) and 15–45 times more infective.Parallel studies of “nonhaloed” Amsacta virions (trypsin-treated) and vaccinia virions showed that both viruses contained similar amounts of protein per OD₂₆₀, but Amsacta virions contained only 36% of the DNA found in vaccinia.     

Cerebellar subjects show impaired coupling of reach and grasp movements

We examined how cerebellar deficits in isolated reaching or grasping movements contribute to abnormalities in a combined reach and grasp movement, and whether people with cerebellar damage show abnormalities in the spatiotemporal relationships of reach and grasp movements. We studied subjects with cerebellar damage and matched controls as they performed a combined reach and grasp, an isolated reach, and an isolated grasp. These movements were performed under slow-accurate and fast speed conditions. Subjects were also tested for their ability to correctly estimate the target size based on visual information. We measured the three-dimensional position of the index finger, thumb and wrist joint during all tasks. Results showed that cerebellar subjects overestimated the target size to a greater extent than did controls. During movement testing, cerebellar subjects were impaired on isolated reach and isolated grasp. However, they did not worsen parameters of reach or grasp movements during the combined reach and grasp. Instead there were distinct deficits in the coupling of the reach and grasp movement. Compared with controls, cerebellar subjects showed abnormalities in the sequence of the reach and grasp movement and highly variable timing of peak grip aperture. In the slow-accurate condition, cerebellar subjects decomposed the reach and grasp movement into separate reach then grasp components, and produced multiple peaks in grip aperture. In the fast condition, cerebellar subjects did not decompose, produced a single peak grip aperture, and dropped the target more often. These results indicate that cerebellar damage can cause a specific breakdown in the coupling of reach and grasp movements. The cerebellum may be involved in combining reach and grasp movements into a single motor program.     

信号转导和转录激活因子6基因多态性与湖北汉族人变应性哮喘的相关性研究

目的　探讨信号转导和转录激活因子 (STAT) 6基因 3′非翻译区G2 96 4A位点多态性和第一外显子GT串联重复序列遗传多态性与湖北汉族人变应性哮喘易感性的关系。方法　用聚合酶链反应 限制性片段长度多态性 (PCR RFLP)技术检测STAT6基因G2 96 4A位点多态性 ;用聚合酶链反应 短串联重复多态性 (PCR STR)技术对STAT6基因第一外显子微卫星进行分型 ,并将PCR产物克隆及测序鉴定 ;采用病例 对照法研究了 1 35例变应性哮喘患者和 1 0 9例对照。结果　 ( 1 )湖北地区汉族人群STAT6基因G2 96 4A位点基因型以GA型最为常见 ;哮喘组与对照组STAT6基因G2 96 4A位点的等位基因频率和基因型频率GG、GA、AA之间差异无统计学意义 (P >0 .0 5)。 ( 2 )STAT6基因第一外显子微卫星多态性共检出GT串联重复次数为 1 3、1 4、1 5、1 6的 4种等位基因 ;第一外显子微卫星的多态性检测出 1 3/1 4基因型在哮喘患者组和正常对照组相比差异具有统计学意义(P =0 .0 0 1 4 )。 ( 3)STAT6基因第一外显子GT二核苷酸串联重复序列多态性中 1 3 GT重复等位基因与 2 96 4A变异体之间存在连锁不平衡 (P =0 .0 0 0 0 2 1 8)。结论　STAT6基因 3′非翻译区G2 96 4A位点多态性与湖北汉族人哮喘易感性无明显相关性 ;第一外显子GT二核苷酸串联重     

Effect of pH and glutathione on lipid peroxidation in tocopherol-enriched liposomes

Tocopherol-enriched liver microsomes are more resistant to lipid peroxidation at an alkaline pH of 8.5 in comparison with microsomes incubated at pH 7.5. An alkaline pH provides conditions for two-electron oxidation of tocopherol, which causes the lipid molecule to revert to the initial state (O₂/H exchange). A possible mechanism of inhibition of lipid peroxidation within the physiological range of pH with participation of a glutathione-dependent enzyme is discussed. Translated fromByullenten' Eksperimental'noi Biologii i Meditsiny, Vol. 120, N ^o 9, pp. 268–270, September, 1995 Presented by E. I. Chazov, Member of the Russian Academy of Medical Sciences