Alzheimer's disease and Down's syndrome: Sharing of a unique cerebrovascular amyloid fibril protein

The cerebrovascular amyloid protein from a case of adult Down's syndrome was isolated and purified. Amino acid sequence analysis showed it to be homologous to that of the β protein of Alzheimer's disease. This is the first chemical evidence of a relationship between Down's syndrome and Alzheimer's disease. It suggests that Down's syndrome may be a predictable model for Alzheimer's disease. Assuming the β protein is a human gene product, it also suggests that the genetic defect in Alzheimer's disease is localized on chromosome 21.     

Comparisons between warm and cold water swim stress in mice

The following experiments evaluated the effects of warm- or cold-water swim stress on tail-flick latencies (TFL) in mice. To first determine the appropriete control group, the TFL's of dry-vs-dunked mice were compared. Dry mice had significantly shorter TFL's than dunked mice, implying that the dampness of the mouse's tail contributed to the increase in the TFL. Therefore, dunked mice were used as the relevant control for the swum mice. Cold water swimming (2°C) produced a significant increase in the TFL; this was not blocked by the opiate antagonist naloxone (3 mg/kg sc) or potentiated by the enkephalinase inhibitor thiorphan (100 mg/kg sc). Warm water swimming (32°C) up to 3 min produced an inconsistent effect on TFL's, implying that the effects were at the threshold of detectability. Naloxone attenuated and thiorphan modestly potentiated the effects of warm water swimming on TFL's. This suggests that warm water swim stress-induced increases in mouse TFL's may involve opioid pathways, whereas cold water swim stress-induced changes in mice TFL's appear not to be opioid mediated.     

Comparison of the in vivo clearance of des-AA and des-AABB rat fibrin monomers prepared by different methods

Solubilization of fibrin monomers (Fm's) is usually performed with dilute acetic acid, urea or sodium bromide. These solvents can affect the biological properties of Fm's. Therefore we describe a new method to keep Fm's in solution, under milder conditions i.e. by generating them in Dcate solutions and avoiding non-physiological conditions. The in vivo behaviour of iodinated rat Fm's injected in rats and prepared by this new method was compared with that of Fm's dissolved in acetic acid, urea or sodium bromide.Fm's prepared in Dcate solutions accumulate rapidly, within 10 minutes after injection, in all organs tested, predominantly in kidney, liver and lung, probably by interaction with endothelial cells. The blood radioactivity remains nearly constant during the first 90 minutes and decreases thereafter exponentially. Fm's dissolved in sodium bromide behave similarly. However, Fm's dissolved in acetic acid or urea behave differently and do not accumulate in organs. This suggests that Fm's loose their capability to accumulate in organs and probably to interact with endothelial cells when they have been dissolved in acetic acid or urea.The slow exponential clearance phase does not differ significantly between the various Fm's and their $\text{T}\text{1}\text{2'S}$ are estimated to lie between 5 and 7 hours.     

Cooperation: The roles of interpersonal value and gratitude

Here we examine the roles of interpersonal valuation and gratitude in the formation of cooperative relationships. Building on prior work, we draw on the concept of a welfare tradeoff ratio (WTR), an internally computed index of the extent to which one person values another person's welfare relative to his or her own. We test several predictions regarding the effects of benefit delivery on changes in WTR, gratitude, and subsequent cooperation. We show that benefit delivery by a stranger: (i) raises the beneficiary's valuation of the stranger's welfare, (ii) predicts downstream cooperative behavior by the beneficiary toward the stranger, and (iii) is coincident with beneficiaries' expressions of gratitude. We find evidence that cooperation and gratitude, while both sparked via benefit delivery and both underpinned by estimates of welfare valuation, are nevertheless produced in parallel via different paths. Specifically, the updated magnitude—not the initial magnitude or degree of change—of a beneficiary's WTR toward a stranger predicts the beneficiary's downstream cooperative behavior. By contrast, the extent to which the beneficiary's WTR positively changes—and not the initial or updated WTR magnitude—predicts gratitude production, a feature proposed to reinforce the benefactor's actions and foreshadow future cooperative intent on the part of the beneficiary. Taken together, our findings point to the possibility that cooperative behavior might operate via internal estimates of welfare valuation, and that gratitude signals benefit reception and the intent to engage in a cooperative relationship.     

Relationships among physical traits,age and social status in Thomson's and Grant's gazelles

Territorial male Thomson's and Grant's gazelles on a commercial game ranch near Nairobi, Kenya, were older, heavier and possessed longer horns than bachelor conspecifics. Among territorial Thomson's gazelles, males accompanied by females were older than solitary individuals but differed little in frame and horn dimensions. Small sample sizes precluded similar analyses for Grant's gazelles. These results suggest the importance of size, age and perhaps experience in determining social status.     

Tannin allocation in blackbrush (Coleogyne ramosissima)

Blackbrush (Coleogyne ramosissima) is a spinescent shrub occurring in nearly monospecific stands in the southwestern United States. Winter browsing by domestic goats stimulates spring twig production by blackbrush plants. Current season's twigs produced by older branches growing on the outer edges of the plant canopy (terminal branches) contained 2.37 times more tannins than did older twigs. Within blackbrush plants, current season's twigs on terminal branches contained 1.34 times more tannins than did current season's twigs on sprouts and younger branches (basal branches). When analysed separately, current season's terminal twigs contained 1.47 times more tannins than did leaves, while current season's basal twigs contained 1.10 times more tannins than did leaves. Phytochemicals, mainly phenolics, in blackbrush reduce its risk of being over-utilized by domestic herbivores, and the occurrence and distribution of tannins in blackbrush lend support to hypotheses dealing with secondary compounds as plant defences.     

Effect of neoaplectanid and heterorhabitid nematodes (Nematoda: Rhabditoidea) on the millipede Oxidus gracilis

At high dosages, infective-stage juveniles of Neoaplectana carpocapsae and Heterorhabditis heliothidis were able to penetrate into and kill the garden millipede. Nematode development was inhibited by host defense reactions which consisted of encapsulation and enmeshment in tracheoles and connective tissue surrounding the millipede's midgut. Foreign bacteria quickly entered the millipede's hemocoel at death and out-competed the nematode's symbiotic bacteria, Xenorhabdus sp. The dauer stages of an unidentified rhabditid nematode were associated with the living millipede. These nematodes reproduced on the millipede's cadaver.     

Hydroxycinnamoyl acid amides and aromatic amines in the inflorescences of some araceae species

Hydroxycinnamoyl acid amides (HCA's) were found to be important components in the inflorescences of different Araceae species. HCA's occurred in large amount in spathes and in the male and female flowers, and were totally absent from the sterile flowers, commonly found on Araceae spadices. Differences in the distribution of HCA's were noted between male and female flowers. Thus the amount of neutral HCA's was always greater in the male than in the female flowers and the female flowers generally contained more basic HCA'S. In the inflorescences of some Araceae species in the Monsteroideae and Philodendroideae (genera Monstera, Raphidophora and Philodendron), the aromatic amines tyramine and dopamine were very abundant, with concentrations ranging from 1 to 4 mg of each amine per g fr. wt.     

Women's evaluations of other women's natural body odor depend on target's fertility status

A large research literature indicates that men perceive women as more attractive when they are at high fertility than at low fertility within the ovulatory cycle. However, it remains unclear whether women also perceive women as more attractive at high fertility. This study examined women's ratings of samples of natural body odor collected from naturally-cycling women at high and low fertility within the cycle and from hormonal contraceptive-using women at mid-cycle. Like men, women rated naturally-cycling women's high-fertility scent samples as more attractive than their low-fertility samples. Women rated hormonal contraceptive (HC) users' scent samples as more attractive than naturally-cycling women's high- and low-fertility samples, though the difference between HC and high-fertility samples was statistically significant only when raters were treated as the unit of analysis. These findings reveal a potentially important role for scent communication in women's perceptions of other women and are consistent with the notion that the ovulatory cycle could influence women's interactions with one another. The findings also highlight the need for rigorous investigations of the possible impacts of hormonal contraception on women's attractiveness and social relationships with other women.     

Whether to have a second child or not? An integrative approach to women's reproductive decision-making in current China

The transition to low fertility worldwide has led to introduction of diverse frameworks across disciplines to understand its causes and consequences. Previous attempts to compare the relative importance of the key factors influencing women's fertility decision-making largely focused on a single rather than multiple steps of decision-making—an important problem if different factors are associated with different steps. Furthermore, insufficient attention has been paid explicitly to husband's and already-born children's influences, two potentially important factors. Here we introduce a framework covering three steps of reproductive decision-making—ideal family size, fertility desire and fertility intention—and test it using multi-level survey data collected from Chinese one-child mothers. Mother's attitudes towards having two children were paramount factors underlying her ideal family size, and husband's and the firstborn child's attitudes were critical to her desire to have a second child, which in turn played a decisive role in her intention to have a second child. Although husband's attitude was related to all steps, most factors were only relevant to one step; e.g., perceived child mortality and value for old-age security predicted ideal family size, admiration—a prerequisite for social learning—for two-child families predicted fertility desire, and physical/economic constraints primarily predicted fertility intention. Our study emphasizes multiple decision-makers in family reproduction; indicates the relative importance of fertility-influencing factors could vary with steps of decision-making; and has important implications for population policy in low-fertility societies.     

Stimulus features of chicks and other factors evoking parental protective behaviour in ring-billed gulls

We examined the role of certain stimuli in parental approach and protection of ‘straying’ chicks by noting the response of ring-billed gulls, Larus delawarensis, to different stimuli placed within their territories. Playback of chick calls and presentation of surgically devocallzed chickes each elicited and oriented parental approach and protective behaviour, although a combination of the two was more effective. Other factors affecting a parent's reaction included the parent's reproductive state whether other offspring were present, the chick's location, and the chick'ssize relative to the parent's own chicks. These response tendencies should increase a gull's probability of responding selectively toward its own chicks before it can individually recognize them, while rejecting foreign chicks.     

Fluorometric Determination of DNA in Aquatic Microorganisms by Use of Hoechst 33258

A method for the determination of microbial DNA in aquatic environments by the use of Hoechst 33258 has been developed. With unsophisticated instrumentation and simple extraction procedures, it is possible to detect from 0.05 to 10 μg of DNA in bacterial cultures or natural water samples. The method is specific for DNA; DNase I treatment of extracts of natural microbial populations removed 95 to 100% of the observed fluorescence. DNA content ranged from 165 ng ml⁻¹ for relatively eutrophic Potomac River water to 27 ng ml⁻¹ for coastal Atlantic Ocean water and was correlated to an acridine orange direct count (r = 0.90).     

Structural biology at the European X-ray free-electron laser facility

The European X-ray free-electron laser (XFEL) facility, under construction in the Hamburg region, will provide high-peak brilliance (greater than 10³³ photons s⁻¹ mm⁻² mrad⁻² per 0.1% BW), ultrashort pulses (approx. 10 fs) of X-rays, with a high repetition rate (up to 27 000 pulses s⁻¹) from 2016 onwards. The main features of this exceptional X-ray source, and the instrumentation developments necessary to exploit them fully, for application to a variety of scientific disciplines, are briefly summarized. In the case of structural biology, that has a central role in the scientific case of this new facility, the instruments and ancillary laboratories that are being planned and built within the baseline programme of the European XFEL and by consortia of users are also discussed. It is expected that the unique features of the source and the advanced features of the instrumentation will allow operation modes with more efficient use of sample materials, faster acquisition times, and conditions better approaching feasibility of single molecule imaging.     

Factors influencing the weight of the doe during pregnancy in different breeds of rabbits

The effect of breed, year of production, age of doe at conception, season of conception and parity on doe's weight at conception, at the 1st, 2nd, 3rd and 4th week of gestation, after kindling and on doe's total weight gain during gestation were studied using data from 250 pregnant does from five breeds of rabbits: Bauscat, Giza White, Baladi Red, Gray Giant Flander and Baladi White. Breed and year of production were the most important factors affecting doe's weight during pregnancy and after kindling while the other factors were of minor influence. Age of doe at conception was not significant for all the weights and total weight gain recorded. Season of conception was the most important factor affecting doe's total weight gain during gestation while all the other factors were of minor importance. The effect of parity was significant for doe's weight at the 4th week of gestation, otherwise it was not significant for the weights and total weight gain recorded. Breed rank for doe's weight at different stages of gestation differed from that for doe's total weight gain during pregnancy. Weights and total weight gain of pregnant does recorded during 1978/79 were higher than those recorded during 1977/78.     

Enhancing effect of lithium and potassium ions on lectin-induced lymphocyte proliferation in aging and down's syndrome subjects

The effect of different concentrations of LiCl or KCl (0.6–20 meq/liter) on PHA-stimulated lymphocytes from young, old, and Down's syndrome subjects was studied. LiCl showed a dramatic enhancing effect on [³H]thymidine incorporation induced by a suboptimal dose of PHA in old subjects and Down's syndrome patients. An increase of [³H]thymidine incorporation in human lymphocytes stimulated by a suboptimal dose of PHA was also observed with KCl. This effect was higher in old subjects than that observed in young and Down's subjects. LiCl and KCl can modulate and partially restore the derangement in early events of mitogen stimulation which seems to be present in lymphocytes from both old and Down's syndrome subjects.     

Simplifying principles for chemical and enzyme reaction kinetics

Tihonov's Theorems for systems of first-order ordinary differential equations containing small parameters in the derivatives, which form the mathematical foundation of the steady-state approximation, are restated. A general procedure for simplifying chemical and enzyme reaction kinetics, based on the difference of characteristic time scales, is presented. Korzuhin's Theorem. which makes it possible to approximate any kinetic system by a closed chemical system, is also reported. The notions and theorems are illustrated with examples of Michaelis-Menten enzyme kinetics and of a simple autocatalytic system. Another example illustrates how the differences in the rate constants of different elementary reactions may be exploited to simplify reaction kinetics by using Tihonov's Theorem. All necessary mathematical notions are explained in the appendices. The most simple formulation of Tihonov's 1st Theorem ‘for beginners’ is also given.     

Huntington's disease: A generalized membrane defect

Huntington's disease, a progressively degenerative neurological disorder inherited as an autosomal dominant trait, results in selective neuronal loss in the basal ganglia and other areas of the brain. Based on research in our laboratory employing electron spin resonance, analytical, enzymatic, biochemical and morphological techniques to study erythrocyte membranes, which are completely outside the central nervous system, we have suggested that Huntington's disease is associated with a generalized membrane defect involving a protein and probably manifested at the external membrane surface. Other workers have subsequently obtained biophysical, biochemical, and morphological results on extraneural tissue in Huntington's disease including erythrocytes, lymphocytes, platelets,and cultured skin fibroblasts that supports this hypothesis. This review will summarize and evaluate the current knowledge of the involvement of a membrane defect in the etiology and pathogenesis of Huntington's disease.     

Effect of phenylhydrazine on the multiple hemoglobins of Rana catesbeiana tadpoles

Tadpoles of Rana catesbeiana immersed in or injected with phenylhydrazine show a preferential loss from the circulation of the electrophoretically fastest hemoglobin (Hb) and retention of the electrophoretically slower Hb's on polyacrylamide disk-gels.The electrophoretically slowest Hb has previously been found to be synthesized in the kidney while the other Hb's are synthesized in the liver. We postulate that the differential response of the tadpole hemoglobins to the action of phenylhydrazine results from the different Hb's being found in different red blood cell lines that originate in different erythropoietic tissues.     

Chemical mutagens: Dosimetry,Haber's rule and linear systems

We present an overall scheme for chemical mutagen risk assessment, which leads naturally to consideration of Haber's rule, a classical concept of toxicology. A rationale is given for considering compartmental models based on mammalian anatomy and physiology as the most reasonable and practical conceptual framework for risk assessment. Haber's rule is extended to the area of chemical dosimetry, defined in terms of our compartmental models. Then it is proved that Haber's rule holds for any system of linear ordinary differential equations with constant coefficients which is physically realizable. Finally, we comment on non-linearities and on the Blum-Druckey model for time-to-occurrence of tumors.     

Effects of a protein-free diet on the DNA-synthesizing and dividing cells in the lymphoid organs of rats. Changes induced by phytohemagglutinin and cortisone invivo

Levels of ³H-thymidine-labeled lymphocytes on autoradiographs of cell smears and mitotic indices (M.I.) were determined in the popliteal lymph nodes (PLN), spleen and thymus of rats fed with a balanced or a protein deprived (PD) diet for 7 weeks. The latter diet reduced the number of labeled cells per 10³ in the spleen but not in the PLN's and the thymus. The M.I.'s were reduced 50% in the spleen and dropped drastically in the thymus. Subplantar injection of phytohemagglutinin (PHA) provoked a sharp increase in the M.I.'s of the PLN's and the spleen, and also moderately increased the labeling index in the PLN's in normal rats. In PD rats PHA no longer influenced the mitoses in the PLN's and the spleen while it considerably increased the proportion of labeled cells in the latter. These discrepancies between DNA-synthesis and mitoses in the thymus and the spleen suggest a premitotic block of the cell cycle after protein deprivation. The effects of a 5 day-cortisone treatment resembled in a large measure the changes induced by a protein-free diet including the arrest of the cell cycle. The thymic lymphocytes were more sensitive to the hormone in PD than in normal rats. On the contrary, in the PLN's and the spleen mainly cortisone-resistant cells remained alive among the DNA-synthesizing lymphocytes after protein deprivation. All these data agree with the hypothesis of an intervention of endogenous glucocorticoids in the protein deficiency-induced lymphoid involution.