Absence of HTLV I from New Zealand

Sera from 1,943 individuals from Auckland, New Zealand, were tested for the presence of serum antibodies to human T cell lymphotropic virus I (HTLV I), mainly with an enzyme-linked immunosorbent assay (ELISA) with cell extracts as target antigen. The individuals tested were blood donors and mostly Caucasian, but included indigenous Maoris and representatives of several groups of Pacific islanders now resident in New Zealand. Also included were 37 patients with various hematological malignancies, including seven with T cell leukemias. Although 1% of samples were positive by ELISA, none of these were confirmed as positives by Western blotting. On the basis of these results we consider that it is unlikely that HTLV I infection occurs in Auckland; however, we cannot exclude the possibility that pockets of virus infection may occur in other parts of New Zealand or the South Pacific.     

Large,Consistent Estimates of the Heritability of Cognitive Ability in Two Entire Populations of 11-Year-Old Twins from Scottish Mental Surveys of 1932 and 1947

Twin studies provide estimates of genetic and environmental contributions to cognitive ability differences, but could be based on biased samples. Here we report whole-population estimates using twins from unique mental surveys in Scotland. The Scottish Mental Surveys of 1st June 1932 (SMS1932) and 4th June 1947 (SMS1947), respectively, administered the same validated verbal reasoning test to almost everyone born in 1921 or 1936 and attending school in Scotland. There were 572 twin pairs from the SMS1932, and 517 pairs from the SMS1947. Information on zygosity was unavailable. A novel application of a mixture distribution was used to estimate genetic and environmental components of verbal reasoning variation by maximum likelihood. We found consistent heritability (~0.70) and shared environment (~0.21) estimates. The estimates did not change substantially when additional quantitative traits (height and weight) were added in a multivariate analysis. More generally for studies in genetics, the methodological innovation developed here implies that large (national) data collections can provide sufficient information on twin pairs to estimate genetic parameters, even without zygosity.     

Heat shock proteins HSP25, HSP60, HSP72, HSP73 in isoosmotic cortex and hyperosmotic medulla of rat kidney

The distribution of heat shock proteins (HSP) HSP60, HSP73, HSP72 and HSP25 in the isoosmotic cortex and the hyperosmotic medulla of the rat kidney was investigated using Western blot analysis and immunohistochemistry. HSP73 was homogeneously distributed throughout the whole kidney. The level of HSP60 was high in the renal cortex and low in the medulla. HSP25 and HSP72 were present in large amounts in the medulla. Only low levels of HSP25 and almost undetectable amounts of HSP72 were found in the cortex. HSP25 exists in one nonphosphorylated and several phosphorylated isoforms. Western blot analysis preceded by isoelectric focussing showed that HSP25 predominates in its nonphosphorylated form in the outer medulla but in its phosphorylated form in cortex and inner medulla. Although this intrarenal distribution pattern was not changed during prolonged anaesthesia (thiobutabarbital sodium), a shift from the nonphosphorylated to the phosphorylated isoforms of HSP25 occurred in the medulla. The characteristic intrarenal distribution of the constitutively expressed HSPs (HSP73, HSP60, HSP25) may reflect different states of metabolic activity in the isoosmotic (cortex) and hyperosmotic (medulla) zones of the kidney. The high content of inducible HSP72 in the medulla most likely is a consequence of the osmotic stress imposed upon the cells by the high urea and salt concentrations in the hyperosmotic medullary environment.     

Ganglion cell density and oil droplet distribution in the retina of brown-eared bulbul (Hysipetes amaurotis)

This study was intended to determine the number and density of both retinal ganglion cells and the oil droplets of cone photoreceptor cells in brown-eared bulbul (Hysipetes amaurotis). For this study birds were killed with proper dose of anesthetic (pentobarbital, 30 mg/kg), and the eyes were removed from the orbital cavity to isolate the retina. For the ganglion cell study retinal whole-mount specimens were prepared and stained with 0.1% cresyl violet. The different types of oil droplets were counted from color microphotographs of freshly prepared retinal samples. The mean total number of ganglion cells was estimated at approximately 2.5×10⁶; with an average density of 16 523 cells/mm². Two high-density areas, namely the central area (CA) and the dorso-temporal area (DTA), are located in the central and dorso-temporal retinas, respectively, in bulbuls (24 032 cells/mm² in the CA; 23 113 cells/mm² in the DTA). Small ganglion cells persisted in the highest density areas, whereas the largest soma sizes were found in the lowest density areas of the retina. Four types of different colored oil droplets — red, orange, green and clear — were identified with an average density of 29 062/mm². Among the different colors, the green oil droplets had a significantly higher population (13 083/mm²) than the others across the retina. The central retina had a significantly higher number of all types of oil droplets, at a density of 60 552/mm². The density and size of the different colored oil droplets were inversely related across the regions of the retina. Taken together, it is concluded that the CA of the retina is an excellent quality area for visual perception due to peak density of ganglion cells and oil droplets. Moreover, each specific oil droplet makes a distinct contribution to visual perception, thereby ensuring that the bird has a retina that best matches its natural environment and feeding behavior.     

Effects of fat content on fat hedonics: cognition or taste?

Understanding and perhaps overriding preferences for fat is important, given the relationship between higher dietary fat consumption and poorer health. We have examined the roles of potential mechanisms for differences in fat preference: actual fat content and expected fat content. The subjects were women (n=192, ages=50-69) recruited to a study of low-fat dietary change. Subjects were randomized to one of the four cells: participants received either a high- or low-fat milkshake at baseline, and half of each group was told that their milkshake was low in fat and the other half high in fat. Women who received a high-fat milkshake consumed more grams than women who received a low-fat milkshake. Women who expected low-fat shakes reported liking them more than those who expected high-fat milkshakes. These data indicate that both physiology and cognition play a role in determining consumption of high- and low-fat foods.     

Kinetic Studies of the Copolymerization of Ethylene with Norbornene by ansa‐Zirconocene/Methylaluminoxane Catalysts: Evidence of a Long‐Lasting “Quasi‐Living” Initial Period

Copolymers of ethylene (E) with norbornene (N) were synthesized using the catalysts rac‐Et(Ind)₂ZrCl₂/MAO ( 1 ), 90%rac/10%meso‐Et(4,7‐Me₂Ind)₂ZrCl₂/MAO ( 2 ), and rac‐H₂C(3‐t‐BuInd)₂ZrCl₂/MAO ( 3 ). Catalyst activity, molar mass (MM), and copolymer composition were studied as a function of time. The polymers showed an unusually narrow molar mass distribution (MMD) and a significant increase of their MM with time for up to one hour, suggesting a “quasi‐living” polymerization at 30 °C. The experimental data were fitted to kinetic equations and the propagation and transfer reactions were described in quantitative terms. Norbornene greatly depressed the propagation rate, along with the chain transfer rate. The more sterically hindered catalysts of the series showed lower propagation and chain transfer turnover frequency than 1 and yielded polymers with a low ( 2 ) to very low ( 3 ) norbornene content. The presence of norbornene in solution seemed to be one of the main factors responsible for the observed “quasi‐living” character of the copolymerization, probably due to coordination of norbornene to the active site. Time‐resolved kinetic studies also allowed for the calculation of the fraction of active metal centers, ranging from 56% ( 3 ) and 66–68% ( 1 ) to 94% ( 2 ) of the total zirconium present, depending on catalyst structure.

Left: molar mass (top) and polydispersity (bottom) as a function of the normalized polymer yield. The dashed line is the theoretical curve for ideal living polymerization. Catalysts 1 (□), 2 (?), and 3 (○) at N/E ratio 12.5 and catalyst 1 (?) at N/E ratio 28.4. Right: enlargement of the low yield section.     

Gas transport during high-frequency ventilation: Theoretical model and experimental validation

We present a theoretical model of gas transport through the dead space during high-frequency ventilation (HFV) with volumes less than dead space volume. The analysis is based on the axial distribution of transit times of gas moving through the dead space. The model predicts that for tidal volumes (V) much less than dead space (V_d), gas exchange will be proportional to the product of frequency (f) and V². If gas transport is analyzed in terms of Fick's law, then the effective diffusion coefficient (D_eff) can be shown to be equal to fV² times a constant, whose value equals the square of the coefficient of dispersion of axial transit times through the dead space . Experimental results in straight tubes fit the predictions of this model quite well. A through the entire dead space of about 30% is more than sufficient to account for gas exchange during HFV in physical models or in intact animals. An axial dispersion of this magnitude can be measured directly from a typical Fowler dead space determination in healthy subjects.     

Self-selecting albino rats exhibit differential preferences for pure macronutrient diets: Characterization of three subpopulations

Analyses of natural feeding behavior in albino male Sprague-Dawley rats demonstrate that, when allowed to self-select from pure macronutrient diets (protein, carbohydrate and fat), these rats of the same genetic strain can be categorized into 3 subpopulations according to either their 24-h or their 12-h nocturnal patterns of nutrient intake. A majority of the animals (HC for high carbohydrate, 50% of the total population) consumed a diet rich in carbohydrate relative to protein or fat, while a smaller population of rats (HF, 30%) preferred the fat diet, and an even smaller population (HP, 20%) chose a high-protein diet. These 3 subpopulations, after a few weeks of maintenance on the diets, differed in their body weight, with the HF rats having a higher body weight than the HP animals, who tended to weigh more than the lightest HC rats. Whereas all subgroups exhibited a similar bimodal distribution of feeding during the nocturnal cycle, with peaks during the early and late dark periods, they were distinguishable on the basis of their nutrient consumption during specific phases of the dark cycle. This difference was most apparent in the early dark phase, when the 3 subgroups exhibited exaggerated preferences for the specific nutrient that was generally preferred over the 24-h cycle. This is in contrast to the middle dark phase, when diet preferences were attenuated or lost, and the late dark phase, when most rats were similar in showing an increased preference for protein and fat and a decreased preference for carbohydrate. The HF group was further distinguished by an unusually strong burst of feeding during the first 2 h of the dark period and an extra peak of feeding in the middle dark period (7th h), both of which were relatively high in fat content.     

适用于医学动态监测数据的稳健参数估计方法

目的 :介绍并分析适用于医学动态监测数据的稳健参数估计方法。方法 :结合分布假设和稳健统计给出了参数估计方法。首次提出了一种迭代求取形状参数稳健估计的算法。结果 :该方法对医学动态监测中某种生理量异常所占百分比值统计量的参数估计优于临床普遍采用的方法。结论 :通过对分布拟合、估计优效性和可实现性、估计稳健性等的理论分析和模拟实验表明该方法是一种高效、可靠的稳健参数估计方法     

The kinetics and distribution of C9 and SC5b-9 in vivo: effects of complement activation.

Many diseases associated with complement activation are characterized by tissue deposition of components of the terminal complement complex (TCC). The ninth component of complement (C9) plays an important role in the cytolytic effects, and may contribute to the non-lethal cell-regulating functions of the TCC. In this study we examined the behaviour of radiolabelled human C9 and its soluble complexed form SC5b-9 in vivo in order to determine the effects of complement activation on its turnover, distribution and molecular size. In normal rabbits the metabolic parameters of 125I-C9 (median and range) were: plasma half-life (t1/2) 25.9 (20.6-29.5) h, fractional catabolic rate (FCR) 5.7 (5.3-7.0)%/h, and extravascular/intravascular ratio (EV/IV) 0.7 (0.6-1.1). The distribution of radiolabelled C9 amongst body tissues was similar to that observed for rabbit serum albumin (RSA). Activation of the complement cascade with i.v. injection of cobra venom factor (CVF) resulted in rapid disappearance of C9 from the plasma and accumulation of protein-bound radiolabeled in the spleen (exceeding the plasma concentration) and the liver. RSA metabolism and distribution were unaffected by CVF. Fine performance liquid chromatography (FPLC) gel filtration of plasma samples suggested that monomeric C9 was the only major radiolabelled protein present during normal turnovers, whereas CVF administration was accompanied by the prompt appearance of a high mol. wt species consistent in size with SC5b-9. When injected directly, 125I-SC5b-9 disappeared rapidly from the plasma, falling by 50% in 0.7 (0.6-0.8) h, and less than 15% remaining after 4 h with accumulation of protein-bound label in the spleen and liver. These results demonstrate the complexity of C9 metabolism during complement activation.