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PubMed1991

Taxonomy, evolution and life cycles.

Three lectures were given, the first on haplodiploidy in the Oxyurida (Nematoda), the second on rodent Oxyurida and the third on the life cycle of Leishmania (Kinetoplastida, Trypanosomatidae). The oral communications and posters were divided into five subsections, covering systematics at supraspecific, specific and subspecific levels, evolution, and life cycles of parasites with hosts in both aquatic and terrestrial environments. A wide range of topics was discussed, including recent developments in the fields of genetics and cellular and molecular biology, and computer-assisted numerical taxonomy.

Animals↗
PubMedDate not supplied

[The life cycle of Maritrema misenensis (A. Palombi, 1940), n. comb. (Trematoda: Microphallidae, Travassos, 1920) from French Mediterranean coast (author's transl)].

The life cycle of Maritrema misenensis (A. Palombi, 1940) n. comb. is described with illustrations. The sporocysts parasite the digestive gland of the Prosobranch snail Cerithium mediterraneum. The cercariae are the same as Cercaria misenensis, A. Palombi, 1940 described from Italian coast. The adults have been obtained by artificial infestations of Larus argentatus michaellis. Their morphological features are same as those of the caribbean species Maritrema patulus W.H. Coil, 1955. When the life cycle of the American species is pointed out, it will be possible to know whether there are two or only one species.

Animals↗
PubMed1987

Chronic illness and the life cycle: a conceptual framework.

This article provides a conceptual framework for thinking about the system created at the interface of chronic illness with the family life cycle. First, a psychosocial typology and time phases of illness schema is described as a necessary, preliminary step to create a common language that bridges the worlds of illness, individual, and family development. This schema organizes similarities and differences between diseases in a manner useful to psychosocial-developmental rather than biomedical inquiry. Then, drawing on several major life-cycle theories in the literature, key concepts (periods of transition, life-structure building and maintaining, centripetality, and centrifugality) are used in a complementary fashion to link these three lines of development. Equipped with these psychosocial languages, consideration is given to transgenerational aspects of illness, loss, and crisis, and the interwoven threads of illness, family, and individual development. Clinical vignettes are provided to highlight this conceptual framework.

Adaptation, Psychological↗
PubMed2002

Crescent bodies of Parachlamydia acanthamoeba and its life cycle within Acanthamoeba polyphaga: an electron micrograph study.

Parachlamydiaceae are endosymbionts of free-living amoeba first identified in 1997. Two developmental stages, elementary and reticulate bodies, were observed; however, their localization and proportions according to culture condition and duration remain unknown. The life cycle of Parachlamydia acanthamoeba within Acanthamoeba polyphaga was studied by transmission electron microscopy of 8-, 36-, and 144-h coculture. Morphometry and quantification were performed using SAMBA software. The elementary body, the predominant stage within the amoebae, was located mainly within their vacuoles. The multiplication of Parachlamydia bacteria by binary fission of reticulate bodies was independently associated with culture in PYG broth (odds ratio [OR] = 4.4; 95% confidence interval [CI], 1.55 to 12.46) and with the presence of reticulate bodies within the amoebae (OR = 2.10; 95% CI, 1.53 to 2.89). A third developmental stage was observed, the crescent body. Its presence outside and inside the amoebae was associated mainly with prolonged incubation time (OR = 3.98; 95% CI, 1.49 to 10.68, and OR = 5.98; 95% CI, 1.75 to 20.4, respectively). Elementary and crescent bodies were released into the extracellular medium within vesicles or after amoebal lysis. For both, phagocytosis was their mode of entry. This electron micrograph study revealed another infective developmental stage, the crescent body, and provided quantitative analysis of the life cycle of P. acanthamoeba within A. polyphaga.

Acanthamoeba↗
PubMed2001

Identifying body residues of HCBP associated with 10-d mortality and partial life cycle effects in the midge, Chironomus riparius.

The relationship between the body residue of 2,2',4,4',5,5'-hexachlorobiphenyl (HCBP) and its effects, including 10-d mortality and chronic sublethal effects on the midge, Chironomus riparius, are examined in a partial life cycle assessment. The alga, Chlorella vulgaris, was loaded with 14C-labeled HCBP and fed to midges as the method for delivery of the toxicant. In a 10-d bioassay, median lethal body residue (LR50) was 0.57 (95% CI: 0.49-0.66) mmol/kg. In the partial life cycle test, midges were fed a mixture of 12C- and 14C-HCBP-laden algae and exposed in four separate tests to assess the different developmental stages representing 2nd to 3rd instar, 2nd to 4th, 2nd to pupa, and 2nd to adult stages. A variety of sublethal endpoints were monitored, including developmental time within a stadium, body concentration at the end of each stadium, body weight, and fecundity (the number of ova) for the female pupae and adults. Overall, midge body concentrations of HCBP increased with increasing exposure concentration. Body weight was not significantly affected by HCBP except during the 4th instar. Body residue also increased with each successive stadium. Developmental time increased significantly with increasing body concentration in 2nd to 4th, 2nd to pupa, and 2nd to adult tests, while there was no statistical significance in developmental time for the 2nd to 3rd instar test. The number of ova decreased significantly in adults with increasing body concentration of HCBP, with an average of 345 ova in controls, 289 ova at 0.028 mmol/kg of HCBP, and 258 ova at 0.250 mmol/kg. These data, which relate chronic endpoints to body residues, suggest that sublethal endpoints in invertebrates are useful for defining sublethal hazards of PCBs. These data also suggest that ecological consequences may result from relatively low body burdens of PCBs.

Animals↗
PubMed2004

Environmental impacts of the Japanese beef-fattening system with different feeding lengths as evaluated by a life-cycle assessment method.

The objectives of this study were to evaluate the environmental impacts of a beef-fattening system using the life-cycle assessment (LCA) method and to investigate the effects of feeding length on the LCA results. The functional unit was defined as one animal, and the stages associated with the beef-fattening life cycle, such as feed (concentrate and rough-age) production, feed transport, animal management, animal body (i.e., biological activity of cattle), and the treatment of cattle wastes, were included in the system boundary. Our results suggest that enteric or gut CH4 emissions of cattle were the major source in the impact category of global warming (2,851 kg of CO2 equivalents), whereas NH3 emissions from cattle waste were the major source in the impact categories of acidification (35.1 kg of SO2 equivalents) and eutrophication (6.16 kg of PO4 equivalents). Feed production also contributed a great deal to all categories. A shorter feeding length resulted in lower environmental impacts in all the environmental impact categories examined in the current study, such as global warming and acidification, although there was a difference in effect of reducing environmental impacts among the categories.

Ammonia↗
PubMedDate not supplied

Molecular paleoecology: using gene regulatory analysis to address the origins of complex life cycles in the late Precambrian.

Molecular paleoecology is the application of molecular data to test hypotheses made by paleoecological scenarios. Here, we use gene regulatory analysis to test between two competing paleoecological scenarios put forth to explain the evolution of complex life cycles. The first posits that early bilaterians were holobenthic, and the evolution of macrophagous grazing drove the exploitation of the pelagos by metazoan eggs and embryos, and eventually larvae. The alternative hypothesis predicts that early bilaterians were holopelagic, and new adult stages were added on when these holopelagic forms began to feed on the benthos. The former hypothesis predicts that the larvae of protostomes and deuterostomes are not homologous, with the implication that larval-specific structures, including the apical organ, are the products of convergent evolution, whereas the latter hypothesis predicts homology of larvae, specifically homology of the apical organ. We show that in the sea urchin, Strongylocentrotus purpuratus, the transcription factors NK2.1 and HNF6 are necessary for the correct spatial expression profiles of five different cilia genes. All of these genes are expressed exclusively in the apical plate after the mesenchyme-blastula stage in cells that also express NK2.1 and HNF6. In addition, abrogation of SpNK2.1 results in embryos that lack the apical tuft. However, in the red abalone, Haliotis rufescens, NK2.1 and HNF6 are not expressed in any cells that also express these same five cilia genes. Nonetheless, like the sea urchin, the gastropod expresses both NK2.1 and FoxA around the stomodeum and foregut, and FoxA around the proctodeum. As we detected no similarity in the development of the apical tuft between the sea urchin and the abalone, these molecular data are consistent with the hypothesis that the evolution of mobile, macrophagous metazoans drove the evolution of complex life cycles multiple times independently in the late Precambrian.

Animals↗
PubMed1999

Complex Life Cycles in a Variable Environment: Predicting When the Timing of Metamorphosis Shifts from Resource Dependent to Developmentally Fixed.

To test models of the timing of and size at metamorphosis, researchers manipulate food at several times during the larval phase of an animal's complex life cycle. Data from diverse taxa show that the age at metamorphosis becomes resource independent (i.e., fixed) at some point during the larval phase. Although existing models have been modified to incorporate a fixed rate of development, none predicts when phenotypic plasticity in metamorphic timing is lost. A graphical model is presented that extends knowledge of a genotype's optimal age and size at metamorphosis in different environments in which resources remain constant throughout the larval phase (i.e., the genotype's reaction norm) to predict when development rate becomes fixed in response to resource variability during the larval phase. Model predictions concur with data from food-switching experiments on anuran tadpoles and barnacle nauplii. As interest in the timing of and size at metamorphosis expands from well-studied taxa (e.g., amphibians) to the many others that have complex life cycles, the predictive model provides a useful tool to design and improve experiments.

Wilbur‐Collins model↗
PubMed1995

The revenge motive: a developmental perspective on the life cycle and the treatment process.

In this article, vengeance and other manifestations of aggression and hostility are differentiated, then the developmental origins and later manifestations of the revenge motive through the life cycle are traced. Consideration is given to each phase of the life cycle, each of which may impart its distinctive stamp onto the patient's desires for revenge. Consistent with this developmental perspective, it is pointed out that desires for revenge may have important adaptive functions, helping the patient contain anxieties associated with developmental tasks that have not been mastered. A brief case example is used to illustrate how unresolved problems from various developmental stages may lend a particular coloration to the patient's later vengeful motives. Also provided is another case history of an early adult homosexual woman. The article is concluded with a set of technical recommendations for working with such patients in psychotherapy and psychoanalysis.

Adolescent↗
PubMed2002

Public participation in life cycle assessment and risk assessment: a shared need.

Life cycle assessment (LCA) and risk assessment are operationally different but share the common purpose of supporting decisions about reducing threats to human welfare. Both analysis methods also involve a complex mixture of science and value judgments reflecting epistemological as well as moral and esthetic values. The inability of risk assessment and LCA to be "value free" has been a source of considerable controversy in both communities. Recognition of the contingent and social nature of human interpretation of the risks and environmental impacts created by public and private decisions has led to an increased appreciation of the importance of involving interested and affected parties in risk characterization. Comparison of the value-based nature of LCA and risk assessment demonstrates the need for participation in LCA. Although the need for participation by affected parties in decision-making processes is gaining acceptance, there is little agreement as to how participation should be structured. Risk assessment and LCA have a shared need for research examining the design and analysis of participation processes appropriate to a given decision context. A proposed framework recommends participation strategies designed to enhance the effectiveness of policy-driven analyses such as risk assessment and LCA based on the level of trust that interested and affected parties have for other policy participants.

Decision Making↗
PubMed1977

New aspects of the life cycle of Pneumocystis carinii.

Pneumocystis is recognized as a cause of pneumonitis in vertebrates, including man. So far an extra-cellular life cycle has been proposed; thick-walled cysts are the site of the formation of so-called intracystic bodies. These intracystic bodies are set free and are supposed to develop into free living thin-walled Pneumocysts ("trophic" stage) (Seifert and Pliess, 1960; Vavra and Kucera, 1970; Campbell, 1972). In this paper we present, based on elaborative ultrastructural studies, data on the existence of both intra-cellular and extra-cellular stages of the parasite which result in a new proposal for the life cycle of the parasite. This short communication will be followed by a more detailed description of our observations.

Animals↗
PubMed2001

Vascular remodelling during the normal and malignant life cycle of the mammary gland.

The mammary gland life cycle is exemplified by massive, physiologically dictated changes in cell number and composition, architecture, and functionality. These drastic upheavals, by necessity, also involve the mammary endothelium, which undergoes angiogenic expansion during pregnancy and lactation followed by ordered regression during involution. In this review, we summarise data obtained using the Mercox methyl methacrylate corrosion cast technique to analyse the mammary gland vasculature during normal development and carcinogenesis. Concomitant with epithelial cell expansion, the mammary vasculature grows during the first half of pregnancy by sprouting angiogenesis whereas the last half of pregnancy and lactation are characterised by the non-proliferative intussusceptive angiogenesis. The vasculature of the lactating gland is composed of a well-developed capillary meshwork enveloping the secretory alveoli with basket-like honeycomb structures. During involution, regression of the vasculature is achieved by regional collapse of the honeycomb structures, capillary retraction, and endothelial attenuation. This process appears partly to involve apoptosis. However, an additional mechanism involving remodelling without cell death, which we have termed angiomeiosis, must exist to explain the morphological observations. Interestingly, in mammary tumours of neuT transgenic mice, both sprouting and intussusceptive angiogenesis was observed simultaneously in the same nodules, a finding with potential implications for cancer therapy. The underlying molecular mechanisms controlling angiogenic modulation in the mammary gland, particularly angiogenic regression and the endothelial:parenchymal interplay, are poorly understood. However, the data summarised in this review indicate that precisely these molecular mechanisms offer novel alternatives for specific and effective treatment of breast cancer.

Animals↗
PubMed1983

Structure of microvillar enzymes in different phases of their life cycles.

Structural changes have been studied during the life cycles of three glycosidases: sucrase-isomaltase (EC 3.2.48-10), lactase-phlorizin hydrolase (EC 3.2.1.23-62), maltase-glucoamylase (EC 3.2.1.20); and three peptidases: aminopeptidase A (EC 3.4.11.7), aminopeptidase N (EC 3.4.11.2) and dipeptidyl peptidase IV (EC 3.4.14.5). The final forms of the enzymes can be divided into at least two groups: the sucrase-isomaltase type, characterized as dimers, which are asymmetric in their hydrophilic parts, have two types of active site and anchor only on one subunit; and the aminopeptidase N type, characterized as dimers, which are symmetric in their hydrophilic part, have only one type of active site and anchor on both subunits. These enzymes are likely to be synthesized on rough endoplasmic reticulum and simultaneously glycosylated into endoglycosidase H-sensitive forms. They are later reglycosylated to endoglycosidase H-resistant forms, which have relative molecular masses similar to the final forms. Enzymes of the sucrase-isomaltase type seem to be synthesized with a polypeptide-chain length corresponding to the sum of both subunits, whereas enzymes of the aminopeptidase N type seem to be synthesized with a polypeptide-chain length corresponding to the constituent subunits themselves. Not much is known about the catabolism of these enzymes. The enzyme activities and the amounts of enzyme protein decrease at the top of the villi, probably due to release into the lumen. The subunits of aminopeptidase N are cleaved by pancreatic proteases to smaller peptides, and sucrase-isomaltase may lose its sucrase polypeptide, while both enzymes remain bound to the membrane.

Aminopeptidases↗
PubMed2006

Life cycle investigation of CO2 recovery and sequestration.

The Life Cycle Assessment of four CO2 recoverytechnologies, combined with nine CO2 sequestration systems, serves to expand the debate of CO2 mitigation methods beyond a single issue-prevention of global warming-to a wider range of environmental concerns: resource depletion, acidic and toxic gases, wastes, etc, so that the overall, and unexpected, environmental impacts may be revealed.

Carbon Dioxide↗
PubMed2005

Ethnic differences in patterns of suicide across the life cycle.

OBJECTIVE: The authors analyzed suicide across the life cycle of different ethnic groups in an urban population equally divided between blacks (44.6%) and whites (48.1%). METHOD: Two data sets were used: 1) all suicides in Fulton County, Ga., from January 1994 through December 2002 and 2) all U.S. suicides reported by the National Center for Injury Prevention in 1999 and 2000. RESULTS: The population rates for suicide in Fulton County were 1.22 per 100,000 black females, 10.74 per 100,000 black males, 9.89 per 100,000 white females, and 21.04 per 100,000 white males. In Fulton County, age at completed suicide was more than a decade lower in blacks than in whites. The median age of black victims was 32 years, with an interquartile range (IQR) of 23-45, and the median for whites was 44 years (IQR=31-58); the difference was significant. The mean ages of victims who were black (mean=36.1 years, SD=17.0) and of "other" race (mean=35.7, SD=14.3) were significantly lower than the mean for whites (mean=46.2, SD=18.5). The national data were similar, but minorities accounted for an even smaller percentage of suicides. Median age at completed suicide for African Americans nationally was 34 years (IQR=24-45) compared to 44 years (IQR=32-58) for Caucasians. CONCLUSIONS: African Americans commit suicide at rates much lower than those for whites, but they do so when much younger and they have a narrow, age-defined window of vulnerability. Age-specific psychopathological processes and protective factors may define suicide risk for each demographic group.

Adult↗
PubMed2006

Marine ecotoxic effect of pulse emissions in life cycle impact assessment.

Characterization factors for ecotoxicity in life cycle impact assessment are traditionally calculated as the product of effect and fate factors. Steady-state multiple compartment models are used to calculate the fate factor, while effect factors are derived from species sensitivity distributions (SSDs) for multiple substances using average or marginal gradients. Others have shown that steady-state multicompartment models can be used to calculate characterization factors if linear dose-response functions are used. Average gradients are linear dose-response functions per definition. Marginal gradients are first-order Taylor approximations of the effect function and require marginal exposure at all points of the compartment. Instantaneous mixing, giving marginal exposure within compartments, is an implicit assumption of the multicompartment model. This paper investigates if the assumption of marginal exposure results in significant errors for the characterization factor. Ecotoxic effect of pulse emissions is simulated in a transient three-dimensional single compartment model of the marine aquatic environment. Results show that the error in characterization factors for the Taylor approximation is less than a factor of two for multisubstance SSDs assuming concentration addition only in the aggregation of toxic effect of substances. Assuming a combination of response and concentration addition may result in a deviation of several orders of magnitude.

Animals↗
PubMed1970

[Study On The Ticks Of Chejudo-Life Cycle]

This study was conducted to study the life cycle of Haemaphysalis bispinosa and Boophilus microplus. The results obtained are summarized as follows. 1. The period of blood-sucking from a host was 20-25 days (average 22.5 days) for Haemaphysalis bispinosa and was 28-43 days (average 35.5 days) for Boophilus microplus. 2. The parasitism period of Haemaphysalis bispinosa on the host was the same as the blood sucking period, but the parasitism period of Boophilus microplus was only 20-23 days (average 21.5 days) because the Boophilus microplus molted its skin while still on the host. 3. The period from hatching to death for Haemaphysalis bispinosa was 73-123 days (average 101 days) and was 63-92 days (average 77.5 days) for Boophilus microplus. 4. The ticks were waiting on the grass for their host. I could find ticks especially on miscanthus purpurascens, braken, and miscanthus grasses. Larvae had climbed to a height of 15-35 cm and there formed groups of 500. Young adults had climbed to a height of 80 cm and there formed groups from 1 to 5. 5. The number of eggs laid was 2,452 by Haemaphysalis bispinosa and 2,836 by Boophilus microplus. 6. Larvae could not survive the winter. Nymph and young adults of Haemaphysalis bispinosa survived the winter. Boophilus microplus survived the winter as eggs.

Journal Article↗
PubMed1984

Host specificity and host range of the genus Sarcocystis in three snake-rodent life cycles.

Three Sarcocystis species with snake-rodent life cycles were studied for their host range and host specificity in systematically related intermediate and definitive hosts. While S. singaporensis and S. villivillosi developed only in murids closely related to the genus Rattus, a third Sarcocystis species (natural definitive host: Bitis nasicornis - syn. Isospora dirumpens ?) showed a broad intermediate host range. This species was found to use several Bitis species as definitive hosts. S. singaporensis and S. villivillosi in contrary produced sporocysts only in three Python species and in Aspidites melanocephalus .

Animals↗