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PubMed1997

Collisions with ice/volatile objects: geological implications--a qualitative treatment.

An aperiodic collision of the Earth with extra-terrestria] ice/volatile bodies is proposed as a mechanism to produce rapid changes in the geologic record. Due to the volatile nature of these bodies, evidence for their impacts, particularly in the ocean might be subtle and best seen as 'spikes' in the geochemical or fossil record against normal background. Differing effects would result depending on the site of the major break-up of the object: in the atmosphere, on land, or in the ocean. This paper focuses on the effects of adding material to the seas, oceans, and atmosphere. The treatment is largely qualitative, however mass balance calculations were used to estimate the relative mass needed to affect changes in a variety of reservoirs. Although actual impactors probably have a variable composition, the effects of water-, C-, N-, and S-containing objects are discussed. In the atmosphere, effects could include increased rain acidity, increased levels of nutrients, and enhanced greenhouse warming/cooling. Oceanic effects might include increased oceanic productivity (nitrogen-containing objects). As a result of increased chemical weathering and/or greenhouse effects, increased temperatures coupled with enhanced productivity could result in wider-spread oceanic anoxia or altered calcite/aragonite stability. Possible examples of such impacts from the geologic record and potential biotic effects are given.

Acid Rain↗
PubMed2006

Aldehyde dehydrogenase is essential for both adult and larval ethanol resistance in Drosophila melanogaster.

The enzyme aldehyde dehydrogenase (ALDH) is essential for ethanol metabolism in mammals, converting the highly toxic intermediate acetaldehyde to acetate. The role of ALDH in Drosophila has been debated, with some authors arguing that, at least in larvae, acetaldehyde detoxification is carried out mainly by alcohol dehydrogenase (ADH), the enzyme responsible for converting ethanol to acetaldehyde. Here, we report the creation and characterization of four null mutants of Aldh, the putative structural locus for ALDH. Aldh null larvae and adults are poisoned by ethanol concentrations easily tolerated by wild-types; their ethanol sensitivity is in fact comparable to that of Adh nulls. The results refute the view that ALDH plays only a minor role in ethanol detoxification in larvae, and suggest that Aldh and Adh may be equally important players in the evolution of ethanol resistance in fruit-breeding Drosophila.

Alcohol Dehydrogenase↗
PubMed2001

Protein kinase C phosphorylates nonmuscle myosin-II heavy chain from Drosophila but regulation of myosin function by this enzyme is not required for viability in flies.

Conventional myosins (myosin-IIs) generate forces for cell shape change and cell motility. Myosin heavy chain phosphorylation regulates myosin function in simple eukaryotes and may also be important in metazoans. To investigate this regulation in a complex eukaryote, we purified the Drosophila myosin-II tail expressed in Escherichia coli and showed that it was phosphorylated in vitro by protein kinase C(PKC) at serines 1936 and 1944, which are located in the nonhelical globular tail piece. These sites are close to a conserved serine that is phosphorylated in vertebrate, nonmuscle myosin-IIs. If the two serines are mutagenized to alanine or aspartic acid, phosphorylation no longer occurs. Using a 341 amino acid tail fragment, we show that there is no difference in the salt-dependent assembly of wild-type phosphorylated and mutagenized polypeptides. Thus, the nonmuscle myosin heavy chain in Drosophila, which is encoded by the zipper gene, appears to be similar to rabbit nonmuscle myosin-IIA. In vivo, we generated transgenic flies that expressed the various myosin heavy chain variants in a zipper null or near-null genetic background. Like their wild-type counterparts, such variants are able to completely rescue the lethal phenotype due to severe zipper mutations. These results suggest that while the myosin-II heavy chain can be phosphorylated by PKC, regulation by this enzyme is not required for viability in Drosophila. Conservation during 530-1000 million years of evolution suggests that regulation by heavy chain phosphorylation may contribute to nonmuscle myosin-II function in some real, but minor, way.

Amino Acid Sequence↗
PubMed1997

Geological record and reconstruction of the late Pliocene impact of the Eltanin asteroid in the Southern Ocean.

In 1995, an expedition on board the research vessel FS Polarstern explored the impact site of the Eltanin asteroid in the Southern Ocean, the only known asteroid impact into a deep ocean basin. Analyses of the geological record of the impact region place the event in the late Pliocene (approximately 2.15 Myr) and constrain the size of the asteroid to be >1 km. The explosive force inferred for this event places it at the threshold of impacts believed to have global consequences, and its study should therefore provide a baseline for the reconstruction and modelling of similar events, which are common on geological timescales.

Aluminum Silicates↗
PubMed1987

Mass extinctions caused by large bolide impacts.

Evidence indicates that the collisions of Earth and a large piece of Solar System debris such as a meteoroid, asteroid or comet caused the great extinctions of 65 million years ago, leading to the transition from the age of the dinosaurs to the age of the mammals.

Biological Evolution↗
PubMed1986

Biological extinction in earth history.

Virtually all plant and animal species that have ever lived on the earth are extinct. For this reason alone, extinction must play an important role in the evolution of life. The five largest mass extinctions of the past 600 million years are of greatest interest, but there is also a spectrum of smaller events, many of which indicate biological systems in profound stress. Extinction may be episodic at all scales, with relatively long periods of stability alternating with short-lived extinction events. Most extinction episodes are biologically selective, and further analysis of the victims and survivors offers the greatest chance of deducing the proximal causes of extinction. A drop in sea level and climatic change are most frequently invoked to explain mass extinctions, but new theories of collisions with extraterrestrial bodies are gaining favor. Extinction may be constructive in a Darwinian sense or it may only perturb the system by eliminating those organisms that happen to be susceptible to geologically rare stresses.

Animals↗
PubMed1998

Current trends, diagnosis, and treatment of enuresis.

This survey describes the evolution of our concept of monosymptomatic bedwetting over the last decades. It takes you briefly through psychology and enuresis. The minor role of bladder pathology is described ending up with focusing on the mismatch between bladder capacity at night-time and urine production. Monosymptomatic bedwetting should currently be regarded as an umbrella diagnosis allocated to children where daytime urinary problems have been excluded. Within the diagnosis of monosymptomatic bedwetting we can nowadays identify at least two groups. One is related to children who have a large night-time urine production and a normal bladder capacity, and the other is related to children who have a large night-time production, but a bladder capacity too small for the normal urine production. The genetic aspects are currently investigated. The results and this kind of research will probably end up in a further subgrouping.

Deamino Arginine Vasopressin↗
PubMed1993

Surgical resection in the management of small-cell carcinoma of the lung.

Surgery has had little impact on long-term survival in patients with small-cell lung cancer (SCLC). With the evolution of modern techniques, however, surgery may play an increasingly valuable role in SCLC. Surgery may potentially cure a select minority of SCLC patients. Patients with peripheral nodules and those with regional disease achieving a complete response to chemotherapy may benefit from adjuvant surgical resection for removal of residual disease. In some cases, surgery may also be preferred over adjuvant radiotherapy, since the latter necessitates lowering the total chemotherapy dose administered to SCLC patients.

Carcinoma, Small Cell↗
PubMed1999

[Philadelphia chromosome-positive chronic myeloid leukemia in the elderly: presenting features, natural history and survival].

BACKGROUND: Among patients with chronic myeloid leukaemia (CML) old people represent a minority whose disease characteristics are not well known. The aim of the study was to analyze the presenting features, the evolutive course, and the survival of older persons with Ph-positive CML. PATIENTS AND METHODS: Forty-four individuals > 65 years diagnosed with Ph-positive CML in a single centre were compared with 292 younger patients. RESULTS: Comparison of the presenting features of chronic phase Ph-positive CML patients yielded the following significant differences: predominance of female sex (15 males/29 females versus 155/137; p = 0.02), higher proportion of patients with anaemic syndrome (12% versus 2%; p = 0.001), lower frequency of splenomegaly (41% versus 68%; p = 0.001), and higher serum levels of uric acid (p = 0.0006) in the older group. Although the latter patients survived significantly less (median survival 36.6 months, 95% CI: 27-46.2, versus 57.6 months, 95%: 51.2-64.1; p = 0.004), 9 of the 33 deaths registered in this group (27%) occurred in the chronic phase of CML, versus 15 (9%) of the 166 deaths in the younger group (p = 0.003). When chronic phase deaths were excluded and leukaemia-related deaths only considered (i.e., those occurring in the BC or the accelerated phase of CML), old patients still had a shorter survival but the difference was no longer significant. CONCLUSIONS: Ph-positive CML features are essentially the same in older and young individuals, since most of the differences observed are attributable rather to the patients' advanced age than to the leukaemia itself.

Aged↗
PubMed2000

Chronic pain in a family of 6 in the context of litigation.

We describe a family of 6 (2 parents and 4 children), evaluated 6 and 8 years after a minor car accident for chronic pain. A near identical complex of multiple physical, constitutional, and psychological symptoms were shared by all family members, all of whom bore the diagnosis of fibromyalgia. The case was brought to court after nearly a decade of symptomatology and extensive use of the health care system. The minor compensation awarded was consumed ultimately by legal fees. Psychosocial/personality issues and iatrogenic and medico-legal contributions in the evolution and resolution of the legal claim are discussed.

Accidents, Traffic↗
PubMed1996

Impact process: an important geological phenomenon.

The impact process was for a long period of time, even after a wider acceptance among the geological community, considered to be a marginal phenomenon in the Earth sciences. The first decade or two have showed an importance of the process itself and consequent events only too clearly. The present paper is a review describing the history and development of the impact hypothesis, structure and origin of impact craters, influence of huge impacts on the living environment and other aspects of the impact process from the point of view of geology s.l.

Animals↗
PubMed1996

Origin of the terrestrial planets and the moon.

Our ideas about the origin and evolution of the solar system have advanced significantly as a result of the past 25 years of space exploration. Metal-sulfide-silicate partitioning seems to have been present in the early dust components of the solar nebula, prior to chondrule formation. The inner solar nebula was depleted in volatile elements by early solar activity. The early formation of the gas giant, Jupiter, affected the subsequent development of inner solar system and is responsible for the existence of the asteroid belt, and the small size of Mars. The Earth and the other terrestrial planets accreted in a gas-free environment, mostly from volatile-depleted planetesimals which were already differentiated into metallic cores and silicate mantles. The origin of the Moon by a single massive impact with a body larger than Mars explains the angular momentum, orbital characteristics and unique nature of the Earth-Moon system. The density and chemical differences between the Earth and Moon are accounted for by deriving the Moon from the mantle of the impactor.

Aluminum Silicates↗
PubMedDate not supplied

A hundred years of progress in electrocardiography. 1: Early contributions from Waller to Wilson.

The 1887 introduction of electrocardiography as a noninvasive investigative technique on man by Augustus Waller, and Wilhelm Einthoven's electrocardiograph from 1901 remain the two major landmarks in the 100-year history of electrocardiography. The progress in our knowledge of the mechanism and interpretation of the ECG has evolved throughout these 100 years in a succession of relatively small steps contributed by many unsung heroes, although often even relatively minor contributions by a few dominant "stars", notably Thomas Lewis and Frank Wilson, are perceived as giant leaps. The gradual evolution of our concepts of the ECG are reviewed against the historical background of the events involved from the time of Waller's discovery to the end of the second world war.

Electrocardiography↗
PubMed1993

[Impact of life events in the course of depression].

The impact of recent life events in the provoking of depressive episodes is well-established, but their weight in the course of depression has not been frequently studied. Some data can nevertheless be extracted from published research: First, life events occurring before the beginning of the episode are predicative neither of the response to treatment, nor of the long-term evolution of major depressive episodes. Reactional depression seem to be more sensitive to placebo than non-reactional depressions, and, minor reactional depression could have a better spontaneous course. Second, stressful life events and long-lasting difficulties contemporary with the episode are some of the more important clues for durability, and sometimes chronicity, of depressive symptoms. Some of those events are independent (not controlled by the subject), but some are also dependent, produced by the subject and his depressive state. On the other hand, certain types of life events (like "neutralizing events" or "fresh start events") and the stress reduction of long-lasting difficulties, seem to favour remission of minor depressions. Third, weight of life events in relapse and recurrence of depression is significant, but seems to be less important than in the release of first depressive episodes. The interaction between life events and the genesis of depression can be observed from sociological, psychological or biological point of view. Future analysis should be based on the distinction between vulnerability factors, which modulate the impact of life events, and susceptibility factors, which can have a sensibilization role.

Adjustment Disorders↗
PubMedDate not supplied

Image-guided fine needle aspiration biopsy. One year experience.

An analysis of one year experience with fine needle aspiration biopsies (FNAB) guided by computed tomography or ultrasound was conducted in a tertiary care reference center. We performed 66 procedures, two of them considered insufficient (97% technical success). The overall sensitivity was 90% and the specificity 100%. There were five false negative and no false positive results. The cytological diagnosis was confirmed with core biopsy of surgical specimen (available in 30 patients, 47%), discharge diagnosis and/or clinical evolution. Twenty seven patients had a positive FNAB for malignancy. The complication rate was 12%, all of them considered as minor complications which resolved with conservative management. There was a concordance between FNAB results and final diagnosis in 91.5% of the cases. Fine needle aspiration biopsy is a very useful diagnostic procedure if performed adequately.

Adolescent↗
PubMed2003

Scale microornamentation of uropeltid snakes.

Microornamentation was examined on the exposed oberhautchen surface of dorsal, lateral, and ventral scales from the midbody region of 20 species of the fossorial snake family Uropeltidae and seven species of fossorial scolecophidian and anilioid outgroups. No substantial variation was observed in microornamentation from the different areas around the midbody circumference within species. All oberhautchen cells were flat and exhibited no major surface features other than occasional posterior margin denticulations, small pores/pits, and narrow, low ridges. This is largely consistent with the hypothesis that friction reduction and dirt shedding are the main selective pressures on microornamentation, given that reducing shine is not of key importance in fossorial animals. Variations among taxa were observed in the shape and size of oberhautchen cells, in the presence of pores/pits, in the presence and size of denticulations on posterior cell margins, and in the level or imbricate nature of cell borders. Six microornamentation characters were formulated, scored, and plotted onto a selected phylogeny. Character evolution and phylogenetic signal were explored, accepting the incomplete understanding of intraspecific variation and of uropeltid interrelationships. There is evidence that all but one of these characters evolved homoplastically, probably by multiple independent origin. There is no clear evidence for character state reversal, but greater phylogenetic resolution is required to test this further. Phylogenetic signal appears to exist in some instances, including possible microornamentation synapomorphies for Uropeltidae and Melanophidium. These derived character states are found elsewhere within Squamata. A microornamentation of narrow, finely, and regularly spaced ridges is associated with scale iridescence. These ridges, and possibly pores/pits, are also associated with scales that are less wettable, and that therefore might be expected to be better at shedding dirt in moist conditions. Testable hypotheses are presented that might explain minor variations in the form of ridges and pits among uropeltids.

Animals↗
PubMed2003

Dynamics of hepatitis C virus quasispecies turnover during interferon-alpha treatment.

Interferon-alpha (IFN) has been shown to accelerate the evolution of hepatitis C virus (HCV) variants (quasispecies) in nonresponder patients. Different sensitivities of HCV variants to IFN are discussed as a possible mechanism. In the present study, quasispecies were investigated in detail by a newly established and validated direct solid-phase sequencing of the hypervariable region 1 (HVR1), during the initial 3 months of IFN therapy. According to single strand conformation polymorphism (SSCP) analysis, 14 of 26 (54%) virologic nonresponders with quasispecies evolution were identified. Six representative patients with SSCP changes were selected for frequent HVR1 sequencing. Pre-existing variants were identified by cloning and sequencing of the pretreatment serum HCV sample. In one patient the major type was substituted by a minor variant within 3 days of treatment while in the majority of patients the pretreatment major type did not decline before days 26-57 of treatment. Total serum HCV RNA levels remained constant in all patients. In conclusion, although quasispecies evolution during IFN therapy is common, it occurs after a wide range of time intervals after initiation of therapy. Thus, nonresponse to IFN cannot exclusively be explained by changes in the quasispecies.

Adult↗