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Biomedical subjects

E Kolb

Publications and source records attributed to E Kolb.

At least 19 recordsLinked to original sources
PubMed2001

Rheology of a confined granular material.

We study the rheology of a granular material slowly driven in a confined geometry. The motion is characterized by a steady sliding with a resistance force increasing with the driving velocity and the surrounding relative humidity. For lower driving velocities a transition to stick-slip motion occurs, exhibiting a blocking enhancement with decreasing velocity. We propose a model to explain this behavior pointing out the leading role of friction properties between the grains and the container's boundary.

Journal Article↗
PubMed2001

A recipe for primordial soup.

If the universe emerged from a state of high temperature and high density, we can study the origin of the universe by recreating those conditions in the laboratory. While we can not reproduce the Big Bang, we can recreate its conditions and study the physical processes responsible for producing the rich and varied universe we observe today.

Extraterrestrial Environment↗
PubMed1997

Potential nitrosamine formation and its prevention during biological denitrification of red beet juice.

High nitrate intake has been shown to result in an increased risk of endogenous formation of N-nitroso compounds. Certain vegetables and vegetable juices contain high concentrations of nitrate. Biological denitrification using strains of Paracoccus denitrificans (P.d.) has been proposed as effective means to reduce nitrate contents in such vegetable juices. During this bacterial denitrification process, substantial nitrite concentrations are transiently formed. This study investigated whether N-nitrosation reactions might occur. The easily nitrosatable amine morpholine was added to red beet juice at high concentration (100 ppm) during denitrification 10 different batches of red beet juice served as raw material. Each batch was submitted to denitrification in the presence and absence of ascorbic acid. In the absence of ascorbic acid, formation of N-nitrosomorpholine (NMOR) was observed in the low ppb range (0.5-8 ppb). Addition of ascorbic acid (500 mg/litre) inhibited the formation of NMOR, except for those instances where the pH was less than 6 and/or nitrate turnover was low (< 200 mg NO3-/litre/hr). Under conditions leading to high rates of nitrate turnover (> 200 mg NO3-/litre/hr), nitrosamine formation can reliably be prevented by ascorbic acid. The results show that bacterial denitrification of red beet juice high in nitrate can be accomplished without the risk of nitrosamine formation.

Ascorbic Acid↗
PubMed1997

[Nutritional biochemical aspects of the significance, of the utilization, of metabolism and of the administration of vitamin E and of selenium in sheep (review)].

A review is given on the significance, availability, metabolism and application of vitamin E and selenium in sheep. Vitamin E deficiency commonly occurs in spring. Selenium deficiency occurs in certain areas where the selenium content of plants is low. A further factor is the low availability of selenium as a consequence of reduction reactions in the forestomachs. When the supply of vitamin E and selenium is suboptimal, activity of the immune system and growth are impaired.

Administration, Oral↗
PubMed1995

Influence of craniofacial surgery on the social attitudes toward the malformed and their handling in different cultures and at different times: a contribution to social world history.

A historic overview including the European, American, Asian, and African continents is given on attitudes toward and the handling of humans with congenital malformations in ancient cultures and on pertinent customs in some prehistoric peoples. Figures of early works of art showing malformed individuals are presented testifying to this worldwide and timeless problem of humankind. In parallel, analogous patient photographs from our hospital before and after reconstructive surgery are shown. Philosophies of ancient Greece, rome, and China on the subject of malformed infants essentially did not differ from the known attitudes of the less developed tribes in Europe and pre-Columbian America, although the means of elimination of unwanted offspring were rather passive (exposure) than active (manual killing). A radical change in attitudes and practices occurred with the spread of the Christian religion and its political installment in Europe. The care for the underprivileged including the malformed ones was considered a Christian duty to be performed with compassion and love. In our century, the clocks have been and apparently are turned back again. Atheistic and Darwinian influences, political atheism, and the belief in "higher ethics" issued by "superman" have led to a relapse into barbarism, also within the medical system. We, as craniofacial surgeons, are privileged to have the means to turn the clocks forward again by rehabilitating the physically most underprivileged: those with conspicuous craniofacial malformations. The necessary techniques exist and are applied, as the figures of patients from our hospital demonstrate, but the will and the emotional strength for their consequent application require more than our hands.

Africa↗
PubMed1995

Enhanced virus resistance of transgenic mice expressing the human MxA protein.

MxA is a GTPase that accumulates to high levels in the cytoplasm of interferon-treated human cells. Expression of MxA cDNA confers to transfected cell lines a high degree of resistance against several RNA viruses, including influenza, measles, vesicular stomatitis, and Thogoto viruses. We have now generated transgenic mice that express MxA cDNA in the brain and other organs under the control of a constitutive promoter. Embryonic fibroblasts derived from the transgenic mice were nonpermissive for Thogoto virus and showed reduced susceptibility for influenza A and vesicular stomatitis viruses. The transgenic animals survived challenges with high doses of Thogoto virus by the intracerebral or intraperitoneal route. Furthermore, the transgenic mice were more resistant than their nontransgenic littermates to intracerebral infections with influenza A and vesicular stomatitis viruses. These results demonstrate that MxA is a powerful antiviral agent in vivo, indicating that it may protect humans from the deleterious effects of infections with certain viral pathogens.

Animals↗
PubMed1995

[The significance of vitamin A for the immune system (review)].

The significance of vitamin A and of its metabolites (retinoic acid a. o.) for the functional capacity of the cells of the immune system (macrophages, T- and B-lymphocytes, killer-cells a. o.) is discussed with special consideration to that of the gastro-intestinal-tract and of the mammary gland. Recommendations for the application of vitamin A in combination with the vitamins D, E and C are given.

Animals↗
PubMed1994

Application of purified bone morphogenetic protein (BMP) in cranio-maxillo-facial surgery. BMP in compromised surgical reconstructions using titanium implants.

After a review of the clinically relevant literature on early modified whole bone products (demineralized bone; AAA bone (Urist et al., 1975))--predecessors of purified bone morphogenetic protein (BMP)--and a summary of the only published clinical experience with purified human BMP (in orthopedic surgery; from the group of Urist; Johnson et al., 1988-1992), an introductory overview of our experience with our own preparations of BMP from bovine bone in 271 procedures on the face and cranium in 145 patients is presented. In this first article of a series of three, major preprosthetic reconstructions using iliac bone grafts and titanium screw implants are described. All patients are examples of compromised bone and/or soft tissue conditions and cannot be considered routine indications for the operations performed. The most endangered implants became osseointegrated after 6 to 8 1/2 months as judged from clinical examination and CT imaging. These results demonstrate the efficacy of purified, concentrated BMP preparations, able unequivocally to induce bone even in areas with seemingly lost implants.

Adult↗
PubMed1994

Application of purified bone morphogenetic protein (BMP) preparations in cranio-maxillo-facial surgery. Reconstruction in craniofacial malformations and post-traumatic or operative defects of the skull with lyophilized cartilage and BMP.

New ways of craniofacial reconstruction in old post-traumatic or fresh donor site craniectomy defects and in congenital malformations (Apert's and Crouzon's syndromes) are described. In all instances a stacked composite of lyophilized cartilage strips interspersed with BMP layers was applied to fill the defects and indentations or used in combination with autologous bone struts to rebuild the cranium completely in synostotic malformations. The stratified implants interlaced with BMP induced early bone formation, and in addition were rigid enough from the beginning to serve as bridging elements over and between autologous bone struts in the cage-like forehead reconstructions. The reconstructed areas became clinically solid after a few months. CT images taken in 4 cases showed progressive calcification starting in the BMP layers, sometimes already visible after a few weeks. These results indicate that the usual slow process of calcification/ossification of lyocartilage alone is considerably accelerated by the combination with BMP. From intermediate term observations (more than one year) we conclude that complete consolidation of the whole implants, so far without signs of resorption, will consistently be the final outcome of this type of reconstruction.

Acrocephalosyndactylia↗
PubMed1994

[The problem of a high content of vitamin A in the liver of calves, cattle, sheep and swine for the consumer. Amount of accumulation and mechanism of teratogenic effect (review article)].

Cases of hypervitaminosis A in men--especially in pregnant women, with development of malformations--are reported. The existence of withdrawal times to slaughter after the application of vitamin-A-containing preparations with a content of 10,000 to 10(6) international units and more is described. The content of vitamin A in the liver of monogastric animals is closely related to that in the feed. In ruminants about 40 to 70% of the vitamin A of the feed is decomposed by the microorganisms in the forestomachs. The amount of vitamin A stored in the liver after a therapeutic application is dependent of the initial content. The velocity of the depletion of the stores at a carotene- and vitamin-A-poor feeding is described. In ruminants and pigs in the account of the properties of the placenta no embryotoxicity of a therapeutic dose of vitamin A is to be expected. The mechanism of the teratogenesis by vitamin A in mice is described.

Abnormalities, Drug-Induced↗
PubMed1994

[Biochemical analysis in dogs of the beagle breed. 2. The content of Na, K, Ca, Mg, total P, Fe, Cu and Zn in tissue of fetuses and dogs of different ages].

In dog fetuses in the age of 45 and 55 days as well as in dogs in the age of one day, of 28 days, of 6 and of 18 months the content of minerals (Na, K, Ca, Mg, total-P), of Fe, of Cu and of Zn in different tissues (cerebrum, cerebellum, brain stem, lung, heart respectively left and right ventricle, liver, spleen, kidney respectively cortex and medulla, pancreas, M. biceps femoris and M. longissimus dorsi) was analysed. During the prenatal and postnatal development there are changes in the content of the mentioned elements in many tissues, that are necessary for the specialisation for certain functions.

Aging↗
PubMed1994

[The concentration of ascorbic acid, glucose and cortisol in the blood plasma of sheep and the excretion of ascorbic acid in the urine after i.v. administration of the compound].

In lambs, adult female sheep and wethers the influence of the intravenous injection of ascorbic acid (AA) in a dose of 10, 20 or 30 mg/kg body weight (b.w.) on the concentration of AA in the plasma up to 420 minutes thereafter was analysed. Further the concentration of glucose respectively of cortisol in the plasma was determined in some experiments. The results can be used as a basis for investigations in sheep with infectious and parasitic diseases for the determination of the degree of the saturation of the body with AA. For therapeutic purposes the repeated application of a dose of 20 mg AA/kg b.w. is recommended. In wethers a dose dependent excretion of AA in the urine after an i.v. injection of a dose of 10, 20 or 30 mg/kg b.w. was observed. The injection of ACTH, cortisol, adrenaline and noradrenaline had no substantial influence on the concentration of AA in the plasma. In the course of 24 hours there was no alteration in the concentration of AA in the plasma.

Animals↗
PubMed1993

The 3' half of the mouse mammary tumor virus orf gene is not sufficient for its superantigen function in transgenic mice.

The Mouse Mammary Tumor Virus (MMTV) long terminal repeat contains an open reading frame (orf) of 960 nucleotides encoding a 36 kDa polypeptide with a putative transmembrane domain and five N-glycosylation sites in the N-terminal part of the protein. Transgenic mice bearing either the complete or the 3' terminal half of the orf sequence of MMTV-GR under the control of the SV40 promoter were raised. As shown previously by FACS analysis transgenic mice which express the complete orf gene have a significant deletion of V beta 14 expressing T cells at 6 weeks of age. Here we show that no clonal deletion of V beta 14 bearing T cells takes place in transgenic mice that contain orf sequences from the fifth ATG to the termination codon. The pattern of tissues expressing the truncated transgene was studied by the Polymerase Chain Reaction (PCR) and was very similar to the one obtained in the V beta 14 deleting animals. These data suggest that the amino-terminal portion of the ORF protein (pORF) is required for a superantigen function, while our previous data indicated that determinants from the carboxy-terminus play an important role for TCR V beta specificity.

Amino Acid Sequence↗