Induction de la tolérance aux allogreffes de peau dans les chimères de l'amphibien urodèle, Pleurodeles waltlii Michah

Development ◽  
1974 ◽  
Vol 32 (3) ◽  
pp. 805-818
Author(s):  
Par P. Goujon
Keyword(s):  
Adult Stage ◽  
Posterior Part ◽  
The Other ◽  
Skin Grafts ◽  
Skin Allograft ◽  
Reciprocal Exchange ◽  
Other Hand ◽  
Skin Allografts ◽  
Pleurodeles Waltlii ◽  
Natural Tolerance

Induction of skin allograft tolerance in chimaeras of urodele amphibian, Pleurodeles waltlii Michah. Allogenic chimaeras were produced in Pleurodeles waltlii (Amphibian, Urodele) by associating the anterior and the posterior parts of two different embryos. A reciprocal exchange between two homologue embryos gave rise to reciprocal allogenic chimaeras. Skin grafts performed in the adult stage between two reciprocal chimaeras are always tolerated. On the other hand, when two skin grafts coming from the anterior and the posterior part of one chimaera are grafted on a common host, one of them may be tolerated and the other rejected: each part of a chimaera keeps its own antigenicity. In allogenic chimaeras, the average natural tolerance for skin allografts is 30 % higher than in sibling controls.

scholarly journals Extraordinary morphological changes in valve morphology during the ontogeny of several species of the Australian ostracod genus Bennelongia (Crustacea, Ostracoda)

2013 ◽  
Author(s):  
Patrick De Deckker ◽  
Koen Martens
Keyword(s):  
Adult Stage ◽  
Morphological Changes ◽  
The Other ◽  
Left Valve ◽  
Ventral Region ◽  
Valve Morphology ◽  
Other Hand ◽  
Early Instar ◽  
Juvenile Stages

Ostracods belonging to the genus Bennelongia differ much in valve morphology between adults and juveniles. Adult valves are asymmetrical, characterised by a beak-like feature in the antero-ventral region of the left valve, and, with some notable exceptions, mostly have smooth or weakly-ornamented valves. Juvenile specimens, on the other hand, have valves that are almost symmetrical, with no beak-like feature and are often heavily ornamented.We have examined the last 3 - 4 juvenile stages of 6 Bennelongia species from 5 different lineages, in order to decipher the types of external valve ornamentation and their recurrences during ontogeny and across lineages. It is clear that ornamentation is more prevalent at the early instar stages compared to the last 2 pre-adult stages, and especially when compared to the adult stage itself.We also examined the surprising presence of a calcified inner lamella with a prominent inner list in the pre-adult stages of Bennelongia species, that is usually absent in juveniles of other ostracods, thus questioning if heterochronic processes have provided an intermediate valve morphology between the simple (normal) cypridinid juvenile state and the heavily derived and modified state of adult Bennelongia.We discuss the possible (speculative) functionality of the ornamentation in juveniles.

Etude histologique de la régénération pharyngienne de Syllis gracilis Grube (Annélide, Polychète)

1974 ◽  
Vol 52 (1) ◽  
pp. 169-177 ◽  
Author(s):  
B. Boilly ◽  
N. Thibaut
Keyword(s):  
Anterior Part ◽  
Posterior Part ◽  
Muscle Cells ◽  
The Other ◽  
Direct Transformation ◽  
Other Hand ◽  
To Come ◽  
Anterior Regeneration ◽  
Radial Muscle

During anterior regeneration of Syllis gracilis Grube (Annelida, Polychaeta), the pharynx (pharyngeal sheath, proboscis, proventricle, and ventricle) completely regenerates. Most of the regenerated pharynx (pharyngeal sheath, proboscis, and proventricle) proceeds from direct transformation of the stomodeal invagination. On the other hand, the ventricle seems to come from both the posterior end of the regenerated proventricle (anterior part of the ventricle) and the intestine of the stump (posterior part of the ventricle corresponding to the ventricular coeca).Tile differentiation of the pharynx is precocious and mainly appears in a particular disposition, and a typical evolution of the cells of the mesodermal sheath surrounding the stomodeal invagination. Starting from the 11th day after amputation, the proventricle differs from the presumptive proboscis by a thick mesodermal sheath which forms the radial muscle cells, the transverse diaphragms, and the peritoneal epithelium. On the other hand, the differentiation of the ventricle comes later (17th day after the section was done).

scholarly journals Clinical implications of the cortical hyperintensity belt sign in fluid-attenuated inversion recovery images after bypass surgery for moyamoya disease

2017 ◽  
Vol 126 (1) ◽  
pp. 1-7 ◽  
Author(s):  
Eika Hamano ◽  
Hiroharu Kataoka ◽  
Naomi Morita ◽  
Daisuke Maruyama ◽  
Tetsu Satow ◽  
...  
Keyword(s):  
Middle Cerebral Artery ◽  
Moyamoya Disease ◽  
Cerebral Artery ◽  
Bypass Surgery ◽  
Vasogenic Edema ◽  
Posterior Part ◽  
The Other ◽  
Neurological Deficits ◽  
Other Hand ◽  
Direct Bypass

OBJECTIVE Transient neurological symptoms are frequently observed during the early postoperative period after direct bypass surgery for moyamoya disease. Abnormal signal changes in the cerebral cortex can be seen in postoperative MR images. The purpose of this study was to reveal the radiological features of the “cortical hyperintensity belt (CHB) sign” in postoperative FLAIR images and to verify its relationship to transient neurological events (TNEs) and regional cerebral blood flow (rCBF). METHODS A total of 141 hemispheres in 107 consecutive patients with moyamoya disease who had undergone direct bypass surgery were analyzed. In all cases, FLAIR images were obtained during postoperative days (PODs) 1–3 and during the chronic period (3.2 ± 1.13 months after surgery). The CHB sign was defined as an intraparenchymal high-intensity signal within the cortex of the surgically treated hemisphere with no infarction or hemorrhage present. The territory of the middle cerebral artery was divided into anterior and posterior parts, with the extent of the CHB sign in each part scored as 0 for none; 1 for presence in less than half of the part; and 2 for presence in more than half of the part. The sum of these scores provided the CHB score (0–4). TNEs were defined as reversible neurological deficits detected both objectively and subjectively. The rCBF was measured with SPECT using N-isopropyl-p-[123I]iodoamphetamine before surgery and during PODs 1–3. The rCBF increase ratio was calculated by comparing the pre- and postoperative count activity. RESULTS Cortical hyperintensity belt signs were detected in 112 cases (79.4%) and all disappeared during the chronic period. Although all bypass grafts were anastomosed to the anterior part of the middle cerebral artery territory, CHB signs were much more pronounced in the posterior part (p < 0.0001). TNEs were observed in 86 cases (61.0%). Patients with TNEs showed significantly higher CHB scores than those without (2.31 ± 0.13 vs 1.24 ± 0.16, p < 0.0001). The CHB score, on the other hand, showed no relationship with the rCBF increase ratio (p = 0.775). In addition, the rCBF increase ratio did not differ between those patients with TNEs and those without (1.15 ± 0.033 vs 1.16 ± 0.037, p = 0.978). CONCLUSIONS The findings strongly suggest that the presence of the CHB sign during PODs 1–3 can be a predictor of TNEs after bypass surgery for moyamoya disease. On the other hand, presence of this sign appears to have no direct relationship with the postoperative local hyperperfusion phenomenon. Vasogenic edema can be hypothesized as the pathophysiology of the CHB sign, because the sign was transient and never accompanied by infarction in the present series.

scholarly journals Lack of Peripherally Induced Tolerance to Established Skin Allografts in Immunologically ReconstitutedScidMice

1992 ◽  
Vol 3 (1) ◽  
pp. 45-50 ◽  
Author(s):  
T. V. Rajan ◽  
Leonard D. Shultz ◽  
Dale L. Greinert
Keyword(s):  
Immune System ◽  
Fetal Liver ◽  
Present Report ◽  
Model System ◽  
Scid Mice ◽  
Peripheral Tolerance ◽  
Skin Grafts ◽  
Skin Allograft ◽  
Clonal Deletion ◽  
Skin Allografts

The mechanism by which the antigen-specific immune system distinguishes between foreign antigens (toward which it mounts an immune response) and self-antigens (of which it is tolerant) is not completely understood. Studies using “superantigens” and transgenic mice have allowed investigations into some of the mechanisms of clonal deletion, anergy, and peripheral tolerance. In the present report, we have attempted to develop a new model system to investigate the possible mechanism(s) of peripheral tolerance to allografts. In this system, skin grafts from C57BL/6J (B6;H-2bmice are grafted onto T- and B-lymphocyte-deficient C.B-17-scid/scid(H-2d; hereafter referred to asscid) mice. Because of their lack of functional lymphocytes, thescidmice readily accept the allogeneic skin grafts. After the allografts healed, the scid mice were reconstituted with T-cell-deficient fetal liver from coisogeneic C.B-17-∤/∤ mice or bone marrow from weanling congenitally athymic BALB/c-nu/nu(H-2d; hereafter referred to asnude) mice. Upon immunological reconstitution, the scid mice reiected the established B6 skin allografts, suggesting that an immune system developing in the presence of an intact peripheral skin allograft fails to develop tolerance to the peripheral allograft. This model system may be useful for the study of the mechanisms required for the induction of peripheral tolerance.

Epidermal culture and grafting. A brief review

1993 ◽  
Vol 83 (8) ◽  
pp. 462-465
Author(s):  
C Muehleman ◽  
RD Wise
Keyword(s):  
Infectious Disease ◽  
Disease Transmission ◽  
Donor Site ◽  
The Other ◽  
Skin Grafts ◽  
Infectious Disease Transmission ◽  
Wound Coverage ◽  
Cutaneous Wounds ◽  
Other Hand ◽  
Technological Advances

In summary, technological advances in culturing epidermis for the purpose of grafting allow this approach in the treatment of cutaneous wounds. Certainly, full- and split-thickness autografts offer immediate availability and permanent wound coverage, but they also involve a large, painful donor site. Cultured epidermal autografts can provide permanent wound coverage, but the delay required for cultivation of confluent sheets of keratinocytes makes them somewhat less desirable. Both allografts and cultured allografts, on the other hand, are available for immediate use, but the possibility of infectious disease transmission may be a concern. In any case, all types of skin grafts function as biological dressings that promote the proliferation of the host's epidermis and, thus, facilitate the ability of the patient's skin to repair itself.

A study of cometary eruptions through OH radio-lines

1999 ◽  
Vol 173 ◽  
pp. 249-254
Author(s):  
A.M. Silva ◽  
R.D. Miró
Keyword(s):  
Short Duration ◽  
Growth Curves ◽  
The Other ◽  
Initial Mass ◽  
Radio Lines ◽  
Other Hand ◽  
Sudden Rise

AbstractWe have developed a model for theH2OandOHevolution in a comet outburst, assuming that together with the gas, a distribution of icy grains is ejected. With an initial mass of icy grains of 108kg released, theH2OandOHproductions are increased up to a factor two, and the growth curves change drastically in the first two days. The model is applied to eruptions detected in theOHradio monitorings and fits well with the slow variations in the flux. On the other hand, several events of short duration appear, consisting of a sudden rise ofOHflux, followed by a sudden decay on the second day. These apparent short bursts are frequently found as precursors of a more durable eruption. We suggest that both of them are part of a unique eruption, and that the sudden decay is due to collisions that de-excite theOHmaser, when it reaches the Cometopause region located at 1.35 × 105kmfrom the nucleus.

Closing the GAP—A 5Å Scanning Microscope

1969 ◽  
Vol 27 ◽  
pp. 6-7
Author(s):  
A. V. Crewe
Keyword(s):  
Normal Form ◽  
The Other ◽  
Resolving Power ◽  
Scanning Microscope ◽  
Conventional Microscope ◽  
Other Hand ◽  
Closing The Gap ◽  
Thermal Sources ◽  
Better Than ◽  
Transmission Microscope

We have become accustomed to differentiating between the scanning microscope and the conventional transmission microscope according to the resolving power which the two instruments offer. The conventional microscope is capable of a point resolution of a few angstroms and line resolutions of periodic objects of about 1Å. On the other hand, the scanning microscope, in its normal form, is not ordinarily capable of a point resolution better than 100Å. Upon examining reasons for the 100Å limitation, it becomes clear that this is based more on tradition than reason, and in particular, it is a condition imposed upon the microscope by adherence to thermal sources of electrons.

Life Beyond 1MeV

1980 ◽  
Vol 38 ◽  
pp. 30-33
Author(s):  
K.H. Westmacott
Keyword(s):  
Electron Microscopy ◽  
Past Experience ◽  
The Other ◽  
Good Case ◽  
Other Hand ◽  
The U.S

Life beyond 1MeV – like life after 40 – is not too different unless one takes advantage of past experience and is receptive to new opportunities. At first glance, the returns on performing electron microscopy at voltages greater than 1MeV diminish rather rapidly as the curves which describe the well-known advantages of HVEM often tend towards saturation. However, in a country with a significant HVEM capability, a good case can be made for investing in instruments with a range of maximum accelerating voltages. In this regard, the 1.5MeV KRATOS HVEM being installed in Berkeley will complement the other 650KeV, 1MeV, and 1.2MeV instruments currently operating in the U.S. One other consideration suggests that 1.5MeV is an optimum voltage machine – Its additional advantages may be purchased for not much more than a 1MeV instrument. On the other hand, the 3MeV HVEM's which seem to be operated at 2MeV maximum, are much more expensive.

Can the Academic Self-Concept be Positive and Realistic?

2005 ◽  
Vol 19 (3) ◽  
pp. 129-132 ◽  
Author(s):  
Reimer Kornmann
Keyword(s):  
Academic Performance ◽  
Opposite Effect ◽  
Self Esteem ◽  
Point Of View ◽  
The Other ◽  
Self Concept ◽  
High Ability ◽  
Self Image ◽  
Other Hand

Summary: My comment is basically restricted to the situation in which less-able students find themselves and refers only to literature in German. From this point of view I am basically able to confirm Marsh's results. It must, however, be said that with less-able pupils the opposite effect can be found: Levels of self-esteem in these pupils are raised, at least temporarily, by separate instruction, academic performance however drops; combined instruction, on the other hand, leads to improved academic performance, while levels of self-esteem drop. Apparently, the positive self-image of less-able pupils who receive separate instruction does not bring about the potential enhancement of academic performance one might expect from high-ability pupils receiving separate instruction. To resolve the dilemma, it is proposed that individual progress in learning be accentuated, and that comparisons with others be dispensed with. This fosters a self-image that can in equal measure be realistic and optimistic.

Stories and the Self

2020 ◽  
Vol 32 (2) ◽  
pp. 47-58 ◽  
Author(s):  
Stefan Krause ◽  
Markus Appel
Keyword(s):  
Meta Analysis ◽  
The Self ◽  
The Other ◽  
Lower Degree ◽  
Contrast Effects ◽  
Self Perception ◽  
Self Perceptions ◽  
Other Hand ◽  
The One ◽  
Implicit And Explicit

Abstract. Two experiments examined the influence of stories on recipients’ self-perceptions. Extending prior theory and research, our focus was on assimilation effects (i.e., changes in self-perception in line with a protagonist’s traits) as well as on contrast effects (i.e., changes in self-perception in contrast to a protagonist’s traits). In Experiment 1 ( N = 113), implicit and explicit conscientiousness were assessed after participants read a story about either a diligent or a negligent student. Moderation analyses showed that highly transported participants and participants with lower counterarguing scores assimilate the depicted traits of a story protagonist, as indicated by explicit, self-reported conscientiousness ratings. Participants, who were more critical toward a story (i.e., higher counterarguing) and with a lower degree of transportation, showed contrast effects. In Experiment 2 ( N = 103), we manipulated transportation and counterarguing, but we could not identify an effect on participants’ self-ascribed level of conscientiousness. A mini meta-analysis across both experiments revealed significant positive overall associations between transportation and counterarguing on the one hand and story-consistent self-reported conscientiousness on the other hand.

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