Magnetoacoustic Waves and the Kelvin-Helmholtz Instability in a Steady Asymmetric Slab: I: The Effects of Varying Density Ratios

Recent observations have shown that bulk flow motions in structured solar plasmas, most evidently in coronal mass ejections (CMEs), may lead to the formation of Kelvin-Helmholtz instabilities (KHIs). Analytical models are thus essential in understanding both how the flows affect the propagation of magnetohydrodynamic (MHD) waves, and what the critical flow speed is for the formation of the KHI. We investigate both these aspects in a novel way: in a steady magnetic slab embedded in an asymmetric environment. The exterior of the slab is defined as having different equilibrium values of the background density, pressure, and temperature on either side. A steady flow and constant magnetic field are present in the slab interior. Approximate solutions to the dispersion relation are obtained analytically and classified with respect to mode and speed. General solutions and the KHI thresholds are obtained numerically. It is shown that, generally, both the KHI critical value and the cut-off speeds for magnetoacoustic waves are lowered by the external asymmetry.

[The sentinel lymph node technique in colorectal cancer using in vivo dye--utility and limits]

The aim of this work is to analyze the importance of sentinel lymph node technique in the treatment of colorectal cancer. There are presented data from literature concerning sentinel lymph node, especially papers about the place of sentinel lymph node method in the treatment of colorectal cancer. This work also shows the experience of Surgical Clinical Department of Coltea Hospital in the use of sentinel lymph node method in colorectal cancer (8 patients with colon cancer and 9 with rectal cancer). There are presented the criteria for inclusion in the study group (26 patients initially proposed for the study) and the exclusion criteria, the diagnostic method using an in vivo dye and the pathology study. The study of the literature and our experience leads to the conclusion that the identification of the sentinel lymph node in colorectal cancer doesn't modify the dissection of the lymphatic area. This procedure may change the adjuvant treatment for colorectal cancer. The discussion is still open concerning the importance of lymphatic micro metastases found by RT-PCR and immunohistochemistry methods. More studies are necessary to clarify these problems.

Insertional polymorphisms of full-length endogenous retroviruses in humans

Human endogenous retrovirus K (HERV-K) is distinctive among the retroviruses in the human genome in that many HERV-K proviruses were inserted into the human germline after the human and chimpanzee lineages evolutionarily diverged [1, 2]. However, all full-length endogenous retroviruses described to date in humans are sufficiently old that all humans examined were homozygous for their presence [1]. Moreover, none are intact; all have lethal mutations [1, 3, 4]. Here, we describe the first endogenous retroviruses in humans for which both the full-length provirus and the preintegration site alleles are shown to be present in the human population today. One provirus, called HERV-K113, was present in about 30% of tested individuals, while a second, called HERV-K115, was found in about 15%. HERV-K113 has full-length open reading frames (ORFs) for all viral proteins and lacks any nonsynonymous substitutions in amino acid motifs that are well conserved among retroviruses. This is the first such endogenous retrovirus identified in humans. These findings indicate that HERV-K remained capable of reinfecting humans through very recent evolutionary times and that HERV-K113 is an excellent candidate for an endogenous retrovirus that is capable of reinfecting humans today.

A HERV-K provirus in chimpanzees, bonobos and gorillas, but not humans

Evidence from DNA sequencing studies strongly indicated that humans and chimpanzees are more closely related to each other than either is to gorillas [1-4]. However, precise details of the nature of the evolutionary separation of the lineage leading to humans from those leading to the African great apes have remained uncertain. The unique insertion sites of endogenous retroviruses, like those of other transposable genetic elements, should be useful for resolving phylogenetic relationships among closely related species. We identified a human endogenous retrovirus K (HERV-K) provirus that is present at the orthologous position in the gorilla and chimpanzee genomes, but not in the human genome. Humans contain an intact preintegration site at this locus. These observations provide very strong evidence that, for some fraction of the genome, chimpanzees, bonobos, and gorillas are more closely related to each other than they are to humans. They also show that HERV-K replicated as a virus and reinfected the germline of the common ancestor of the four modern species during the period of time when the lineages were separating and demonstrate the utility of using HERV-K to trace human evolution.

Many human endogenous retrovirus K (HERV-K) proviruses are unique to humans

BACKGROUND

Endogenous retroviruses contribute to the evolution of the host genome and can be associated with disease. Human endogenous retrovirus K (HERV-K) is related to the mouse mammary tumor virus and is present in the genomes of humans, apes and cercopithecoids (Old World monkeys). It is unknown how long ago in primate evolution the full-length HERV-K proviruses that are in the human genome today were formed.

RESULTS

Ten full-length HERV-K proviruses were cloned from the human genome. Using provirus-specific probes, eight of the ten were found to be present in a genetically diverse set of humans but not in other extant hominoids. Intact preintegration sites for each of these eight proviruses were present in the apes. A ninth provirus was detected in the human, chimpanzee, bonobo and gorilla genomes, but not in the orang-utan genome. The tenth was found only in humans, chimpanzees and bonobos. Complete sequencing of six of the human-specific proviruses showed that full-length open reading frames for the retroviral protein precursors Gag-Pro-Pol or Env were each present in multiple proviruses.

CONCLUSIONS

At least eight full-length HERV-K genomes that are in the human germline today integrated after humans diverged from chimpanzees. All of the viral open reading frames and cis-acting sequences necessary for HERV-K replication must have been intact during the recent time when these proviruses formed. Multiple full-length open reading frames for all HERV-K proteins are present in the human genome today.

[Intra-anesthetic hypothermia]

Oesophageal temperature was recorded after induction of anesthesia, and further, at one, two and three hours. Temperature in the operation hall was continuously monitored. In relation to the temperature in the operating hall the effects on the patient were of three kinds: 1. operating halls with low temperatures (under 21 degrees C) where all the patients become hypothermic; 2. operating halls with an intermediate temperature (21-24 degrees C), where 67% of the patients remain normothermic; 3. operating halls with high temperatures (above 24 degrees C) where all the patients remain normothermic, although these temperatures are uncomfortable for the medical personnel, and increase the septic risk of the patient. When the oesophageal temperature of the patients falls by 0.5 degrees C chills will occur in 40% of the patients. Thermal falls of less than 0.5 degrees C will also determine chills but in only 10.5% of the cases. Immediate postanesthesia chills are also recorded in normothermic patients, but there is a direct relationship between the temperature in the operating hall, the degree of hypothermia and the frequency of chills, while the site of the surgery or the duration of the operation have but an unsignificant influence on intra-anesthetic temperature.