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1.
Additional information is presented in support of the hypothesis (Polednak: Am. J. Phys. Anthropol. 41:49-58, 1974) that in some black populations certain connective-tissue responses, which are involved in protection against infection and repair after injury, also may predispose to specific chronic diseases. These diseases include some autoimmune disorders (i.e., systemic lupus erythematosus, sarcoidosis, and scleroderma) and various benign and malignant tumors involving connective-tissue cells. Complex interactions between genetic factors (HLA and non-HLA loci) and environmental agents may be involved both in the etiology of these autoimmune diseases and in population differences in the incidence of these diseases. A framework is reviewed whereby cellular responses to infectious agents, involving chiefly immunoglobulin-producing cells and macrophages, may have consequences in terms of pathogenesis of specific chronic diseases more common in some black populations. The possible role of natural selection in maintaining some of these diseases is also considered, along with the need for involvement of biomedical anthropologists in their investigation.  相似文献   

2.
3.
The effects of invasive species on native fauna are understudied, even though their consequences should be taken into consideration for the proper conservation and management of marine systems. Furthermore, bioinvasions may have greater consequences if they affect key structural species with slow dynamics such as marine sponges. We propose that reproductive output could be used as a potential early warning signal to detect possible future changes in population trends of long-lived species (i.e. sponges) as a result of biological invasions. The aim of this study was to investigate the effects of invasive algal (Womersleyella setacea) overgrowth on sponge reproduction by comparing the presence of reproductive elements (spermatic cysts, oocytes, embryos, and larvae) in sponges covered by a thick carpet of the invasive algae and in sponges dwelling in the same habitat but without the invasive algae. Three variables were calculated to assess the impact of the invasive alga on sponge reproduction: the reproductive effort, the proportion of individuals in reproduction, and the size of the reproductive structures. We studied eight sponge species representing the main components of the deep rocky reefs of the area. Our results showed that W. setacea had a strong negative effect on sponge reproduction in six out of eight sponge species studied, with lower and even nil reproductive structures on the sponges subjected to the algal overgrowth. Thus, considering that sexual reproduction is necessary for the persistence of most sponge populations, a significant and constant reduction of the reproductive effort may compromise their viability and affect future trends in these benthic systems.  相似文献   

4.
Hoof overgrowth in Holstein--Friesian dairy cattle   总被引:1,自引:0,他引:1  
The genetic etiology of hoof overgrowth, a widespread problem in Holstein-Friesian cattle, was examined. Although all four feet are affected, the hind feet usually have a greater degree of overgrowth. There is a distinct age tendency for the trait; the younger cows' hooves grow faster than those of the older cows, but the overgrowth in older cows reaches greater proportions. Analysis of variance of chi-square frequency tests showed that there is a component of heritability involved in the expression of the trait, but that it follows a more complex model than a simple autosomal recessive gene would show.  相似文献   

5.
Proteoglycans of human gingival epithelium and connective tissue.   总被引:1,自引:0,他引:1       下载免费PDF全文
Proteoglycans extracted from separated specimens of healthy human gingival epithelium and from connective tissue have been purified. The epithelial proteoglycans fractionated as a single included peak on Sepharose 4B-CL and contained heparan sulphate and dermatan sulphate glycosaminoglycans. The connective-tissue proteoglycans separated into three major populations on Sepharose 4B-CL, one of which was excluded from this gel under associative conditions (0.5 M-sodium acetate, pH 7.4). Subsequent fractionation of the excluded material under dissociative conditions (4 M-guanidinium chloride/0.05 M-sodium acetate, pH 7.4) revealed an absence of any aggregate formation of molecules within this population. The connective-tissue proteoglycans contained heparan sulphate, dermatan sulphate and chondroitin 4-sulphate, the proportions of which varied with the molecular size of the proteoglycans. Amino acid analysis of the protein cores of gingival-epithelial and connective-tissue proteoglycans revealed differences that were similar to the differences described between other types of proteoglycans such as those from skin.  相似文献   

6.
Hepatic parenchymal and nonparenchymal cells are highly susceptible to ethanol and its metabolites, and excessive alcohol consumption results in damage to the liver. Ethanol induces an increased prevalence for bacterial overgrowth in the small intestine and translocation of endotoxin into the portal blood. Some studies have pointed to a role for activation of Kupffer cells by gut bacteria-derived endotoxin as a primary event in mechanisms of alcoholic liver injury (ALD). GW4064, a potent farnesoid X receptor (FXR) agonist, has been developed as a hepatoprotective agent, and has been used in animal models of a variety of liver diseases. At the same time, previous experimental results showed that BAs and GW4064 inhibit bacterial overgrowth in the small intestine. It is logical to postulate that GW4064 may control or alleviate the ethanol-induced liver injury through inhibiting gut bacterial overgrowth. GW4064 activates FXR, which induces the expression of several genes with potential functions in mucosal defense to prevent intestinal bacteria overgrowth and translocation into the circulation induced by ethanol, and then will alleviate ethanol-induced liver injury. The hypothesis will provide the brand-new direction that we may prevent and treat ALD by using GW4064 through activating FXR to control gut bacteria overgrowth.  相似文献   

7.
We have investigated conditions that inhibit the tendency of CHO K1 cells to form cellular bridges between microcarriers and dense clumps of cellular overgrowth in microcarrier cultures. Microcarrier aggregation by cellular bridge formation was found to occur only during periods of rapid cell growth. The level of microcarrier aggregation decreased with increasing agitation intensity. Dense masses of cellular overgrowth formed inside bridges connecting the microcarriers and in clumps that protruded off the microcarrier surface. To replace cells that were continuously sheared from the microcarriers, cell growth occurred preferentially in areas of overgrowth after confluent microcarriers were maintained in a serum-free medium. This ultimately led to poor surface coverage as bare spots developed on the microcarrier away from the areas of dense cellular overgrowth. The development of bare spots was inhibited when confluent microcarriers were maintained in medium supplemented with 1% serum. The development of cellular overgrowth was inhibited by dimethyl sulfoxide. Thus, maintaining confluent microcarriers in medium supplemented with 1% dimethyl sulfoxide and 1% calf serum resulted in microcarriers that appeared similar to monolayer cultures. There was also a decrease in bridging in cultures supplemented with either 1% calf serum or 1% dimethyl sulfoxide/1% calf serum compared to serum-free cultures.  相似文献   

8.
P D Ross  F B Howard  M S Lewis 《Biochemistry》1991,30(25):6269-6275
Five highly palindromic DNA dodecamers, four of which may form G-A or I-A purine-purine mispairs at either the 5.8 or 6.7 positions, have been studied at sedimentation equilibrium in the analytical ultracentrifuge. Each DNA oligonucleotide forms an equilibrium mixture of ordered antiparallel hairpin and double-stranded helical structures in solutions of 0.1 or 0.5 M NaCl between 5 and 40 degrees C. The dimeric duplex is favored by conditions of high salt and low temperature. The monomer-dimer equilibrium constants vary from 5 x 10(6) to 5 x 10(3) and are unique for each DNA dodecamer. Analysis of the temperature dependence of the equilibrium constants shows that the double helix to hairpin conversion is driven by a positive entropy change and is associated with an endothermic enthalpy change. The mispair substitutions at the 5.8 positions and the IA(6.7) mispair have the greatest tendency toward hairpin formation and exhibit significantly larger entropy changes than the nonmispaired dGGTACGCGTACC parent sequence and the thermodynamically similar GA(6.7) DNA. The consequences of such hairpin-double helix equilibria must be considered in the interpretation of other kinds of experiments carried out on oligonucleotides at different concentrations.  相似文献   

9.
Summary Experimental overgrowth was produced in chick embryo brains according to the method described earlier (1955, 1959). Pieces of overgrown mesencephalic tissue were cultured in vitro or studied with transplantations to the braincavity of host embryos.When cultured in vitro, cell strands developed in some cultures, showing differences in growth rate and capacity of fibrinolytic activity as compared with normal neural epithelium.After transplantation to the brain-cavity, one case out of six showed a well delimited tumorous formation of a very benign appearance. In the other five cases, the graft tissue had completely merged with the host tissue, showing invasion into the latter. Numerous mitoses were seen and lots of rosette formations. It is concluded that the overgrowth cells may show a strong tendency to invade brain tissue.The cost of this investigation was defrayed by a grant from the Swedish Medical Research Council.  相似文献   

10.
Inclination toward eveningness is often associated with risky behavior. But the existing studies are scarce, inconsistent and usually limited to self-reported measures. We sought to investigate in young adults whether morningness-eveningness is associated with risky behavior in dangerous driving situations, with self-reported drunk driving and with alcohol consumption. Results show that, indeed, inclination toward eveningness is associated with these risky behaviors. We also demonstrate a link between morningness-eveningness and sensation seeking. Therefore, young adults with a tendency toward eveningness might be more at risk to face negative consequences of alcohol abuse or to be involved in a road accident.  相似文献   

11.
Ubiquitination is an essential process regulating turnover of proteins for basic cellular processes such as the cell cycle and cell death (apoptosis). Ubiquitination is initiated by ubiquitin-activating enzymes (E1), which activate and transfer ubiquitin to ubiquitin-conjugating enzymes (E2). Conjugation of target proteins with ubiquitin is then mediated by ubiquitin ligases (E3). Ubiquitination has been well characterized using mammalian cell lines and yeast genetics. However, the consequences of partial or complete loss of ubiquitin conjugation in a multi-cellular organism are not well understood. Here, we report the characterization of Uba1, the only E1 in Drosophila. We found that weak and strong Uba1 alleles behave genetically differently with sometimes opposing phenotypes. Whereas weak Uba1 alleles protect cells from cell death, clones of strong Uba1 alleles are highly apoptotic. Strong Uba1 alleles cause cell cycle arrest which correlates with failure to reduce cyclin levels. Surprisingly, clones of strong Uba1 mutants stimulate neighboring wild-type tissue to undergo cell division in a non-autonomous manner giving rise to overgrowth phenotypes of the mosaic fly. We demonstrate that the non-autonomous overgrowth is caused by failure to downregulate Notch signaling in Uba1 mutant clones. In summary, the phenotypic analysis of Uba1 demonstrates that impaired ubiquitin conjugation has significant consequences for the organism, and may implicate Uba1 as a tumor suppressor gene.  相似文献   

12.
Studies documenting and quantifying personality traits are common in animal behavior. Such studies often consider the nature of individual variation and personality as correlated with a variety of natural history, physiological, or ecological traits, and therefore consider the importance of personality for strategies in wild systems. Though such studies have contributed markedly to our understanding of the important aspects of personality that may covary with a variety of factors that might affect fitness, much of the research on animal personalities is taxonomically limited. To supplement and compliment the laboratory study of reptile personality, we examined the patterns of multiple personality traits in wild Eastern painted turtles (Chrysemys picta) in the field. We examined patterns of aggression, sociability, and boldness across these traits in different contexts in 103 adult, wild-caught turtles. We found strong correlations both within and among the focal behavioral axes, representing robust evidence for personality in this species. Specifically, we found strong relationships among many measures of aggression, as well as relationships between aggression and our measures of boldness. Finally, we note a tendency for sociability in our turtles, with animals scoring high on sociability showing lower tendency toward aggression. Overall, our study provides robust evidence for correlated suites of behavioral traits, or personality, in a semi-aquatic turtle surveyed in the wild. Future work should continue to expand the range of traits examined to more fully consider the ecological consequences of variation in personality in this and similar species.  相似文献   

13.
A homologous chimeric prostate was produced by implantation of intact fetal urogenital sinus(es) (UGS) into the ventral prostate gland (VP) of an adult athymic mouse. A 10- to 20-fold overgrowth of the chimeric lobe of ventral prostate gland, as measured by glandular wet weight and by DNA content, was observed 4 to 9 wk following UGS implantation. The overgrowth was prostate-like as indicated by histologic composition and by responses to endogenous androgen, and was composed of both host and donor cells in about equal proportions as shown by glucose phosphate isomerase isozymic profiles. Unlike the canine model for prostatic hyperplasia, the mouse prostatic overgrowth occurred in the complete absence of exogenous sex steroids. The histoarchitecture of the chimeric VP and the isozymic detection of the contribution to the overgrowth by host cells have provided strong evidence that adult prostatic cells have been recruited to respond proliferatively by cellular interactions with fetal UGS. The demonstration of cellular interactions followed by reactivation of the fetal growth potential provides direct experimental evidence in support of McNeal's hypothesis that the reactivation of fetal growth potential may account for the development of human benign prostatic hyperplasia (BPH).  相似文献   

14.
In sessile and sedentary organisms, competition for space may have fitness consequences that depend strongly on ecological context. Colonial hydroids in the genus Hydractinia use an inducible defense when encountering conspecifics, and intraspecific competition is common in natural populations, often resulting in complete overgrowth of subordinate competitors. My goal in this study was to quantify the impacts of agonistic interactions in Hydractinia [GM] (an undescribed species from the Gulf of Mexico) in terms of three primary fitness components: colony survival, growth rate, and immature gonozooid production. The results demonstrate that the fitness consequences of intraspecific competition depend on the size at which competitive encounters are initiated and the growth form (an indicator of competitive ability) of the competitors. Moreover, some competing colonies consistently produced more immature gonozooids than the controls without competition, and they exhibited extremely low mortality even after 90 days of growth. These results have several ramifications. First, agonistic interactions do not always proceed to competitive elimination. Second, the increase in production of immature gonozooids--an investment in future reproduction--in response to intraspecific competition supports the hypothesis that indeterminately growing organisms increase sexual reproductive effort when growth becomes limiting. Lastly, in light of known ontogenetic variation in the ability of Hydractinia to differentiate among genetically related colonies, strongly size-dependent fitness consequences are consistent with an adaptive, kin-discriminating allorecognition system.  相似文献   

15.
The data on the degree of overgrowth of the Rybinsk Reservoir and reserves of macrophytes biomass received in 2003 and 2009 are presented. It is shown that, in years with low water levels, vast areas of shallows with thickets of coastal aquatic plants dry up and, therefore, the degree of weediness of the reservoir and reserves of macrophyte biomass within it fall significantly. At a high water level, some of them are flooded, which leads to a significant increase in the degree of weediness of the reservoir. Each time it is higher than the previous peak, which testifies to the pulsating character of the overgrowths and to the general tendency toward a slower reduction of the reservoir area.  相似文献   

16.
Encrusting algae are well-known to be able, for long periods, to withstand shading and overgrowth by other organisms. How this is achieved remains a mystery. It had been proposed that connections with unshaded (non-overgrown) parts of the thallus may allow transfer of nutrients to the shaded part. From this model, I proposed and tested the hypothesis that shaded patches of the intertidal red alga, Hildenbrandia rubra, would survive overgrowth longer, or better, when connected to unshaded thallus than when experimentally separated from surrounding alga. Experimental treatments were shading (black or transparent 80 mm perspex discs or no cover) and scraping (scraped around the disc to remove contacts, a control for effects of scraping, no treatment). The 9 orthogonal combinations of cover and scraping were applied to 3 independent, random replicates (i.e. 27 plots) in each of four randomly chosen sites.

In all 4 sites, over 13 months, shaded H. rubra survived in greater abundance (as % cover) where in contact with surrounding thallus. In one site, there was no effect of shading unless the thallus was isolated. In two sites, shading reduced cover, but was more deleterious where the thallus was isolated. In the fourth site, there were artefacts due to a perspex cover, but still less cover of alga where it was isolated.

This encrusting alga can withstand a long period of complete shading, provided there is connection to unshaded thallus. Interpreting or predicting overgrowth interactions in terms of competitive outcomes is therefore dependent on consideration of whether the overgrown species is actually being affected. It also depends on the duration of overgrowth and, as shown here, the extent to which connectivity with unshaded thallus is effective at preventing or reducing any consequences. Observations and experiments that do not ascertain these are difficult to interpret.  相似文献   


17.
Recessive lethal mutations of the lethal(2)giant discs (l(2)gd) and lethal(2)fat (l(2)ft) loci of Drosophila melanogaster cause imaginal disc hyperplasia during a prolonged larval stage. Imaginal discs from l(2)ft l(2)gd or Gl(2)gd double homozygotes show more extensive overgrowth than in either single homozygote, and double homozygous l(2)ft l(2)gd mitotic clones in adult flies show much more overgrowth than is seen in clones homozygous for either l(2)gd or l(2)ft alone. dachsous (ds) also acts as an enhancer of l(2)gd, producing dramatically overgrown discs and causing failure to pupariate in double homozygotes. The comb gap (cg) mutation, which also interacts with ds, greatly enhances the tendency of imaginal discs from l(2)gd larvae to duplicate as they overgrow. If l(2)gd homozygotes are made heterozygous for l(2)ft, then several discs duplicate, indicating that l(2)ft acts as a dominant enhancer of l(2)gd. l(2)ft also acts as a dominant enhancer of l(2)gd, and conversely l(2)gd acts as a dominant modifier of l(2)ft. The enhancement of overgrowth caused by various mutant combinations is accompanied by changes in expression of Decapentaplegic and Wingless. These results show that tumor suppressor genes act in combination to control cell proliferation, and that tissue hyperplasia can be associated with ectopic expression of genes involved in pattern formation.  相似文献   

18.
Activity of hydrolases, acid and alkaline phosphatases (AP and A1P) in connective-tissue capsules as well as the amount of cyclic nucleotides in the rat blood plasma with implantation of polyurethane on the basis of polyoxytetramethylenglycol and 4,4'-diphenylmethane diisocyanate with lactose in the main chain were studied. Data obtained indicate that polyurethane with lactose in the main chain is biocompatible and nontoxic and may be recommended for the purposes of endoprosthesis.  相似文献   

19.
It has been proposed that scleroderma in particular or connective-tissue diseases in general may be caused by exposure to silicone-containing materials used for breast augmentation. We performed a historical cohort study to estimate the point prevalence of this potential complication sometimes referred to as "human adjuvant disease." Three-hundred and seventy-eight patients who underwent augmentation mammaplasty with silicone-containing envelope-type prostheses from 1970 through 1981 were surveyed. Regional musculoskeletal syndromes, fibrositis, or osteoarthritis occurred in a third (38 of 125) of our responders. No patient developed an inflammatory systemic rheumatic disease during the period of observation (mean 6.8 years for the 125 subjects). Using calculations based on risk for development of rheumatic disease, it does not appear likely that augmentation mammaplasty is a significant or major inducer of inflammatory connective-tissue diseases in general. However, the number of patients surveyed was small, and our results must be considered preliminary. We could not exclude a specific risk for the development of scleroderma.  相似文献   

20.
The Marfan syndrome is a dominantly inherited connective-tissue disorder characterized by ocular, cardiovascular, and musculoskeletal abnormalities. Although the underlying biochemical and molecular defect(s) of this pleiotropic disease is currently unknown, we have consistently observed apparent diminished content of elastin-associated microfibrillar fibers accumulating in skin, or produced by cultured fibroblasts, from patients with the Marfan syndrome and have documented the cosegregation of these immunofluorescent abnormalities of microfibrillar fibers with the Marfan syndrome phenotype in family studies. Recently, an unusual patient has been described with unilateral phenotypic features of the Marfan syndrome, providing an unique opportunity to compare microfibrillar fibers and other connective-tissue components between the affected and nonaffected sides. In the present report, we demonstrate striking differences in apparent content of microfibrillar fibers, as determined by indirect immunofluorescence of skin and fibroblast cultures, that are revealed when multiple homologous samples derived from different sides of the patient's body are compared. In contrast, no differences in apparent content of type III collagen or in the biosynthesis and apparent structure of types I and III (pro)collagens were found. HLA types and chromosome heteromorphisms were identical in fibroblasts from both sides of the body, eliminating the formal possibility of chimerism and suggesting that a postzygotic mutation accounts for the asymmetric manifestation of the Marfan syndrome in this patient. The observation of striking decreases in microfibrillar fibers on the affected side of the body provides further evidence that abnormalities of this component of the elastic fiber system may be central to the pathogenesis and possibly the etiology of the Marfan syndrome.  相似文献   

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