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Biomedical subjects

J Urban

Publications and source records attributed to J Urban.

At least 19 recordsLinked to original sources
PubMed1992

15gag proteinase of myeloblastosis-associated virus: specificity studies with substrate-based inhibitors.

The specificity of the proteinase of myeloblastosis-associated virus (MAV) was studied with (a) 21 substrate-based inhibitors, (b) 9 inhibitors with pseudopalindrome sequences, (c) 8 chimeric inhibitors, and (d) 3 compounds designed as human immunodeficiency virus 1 (HIV-1) proteinase inhibitors. The central inhibitory unit (transition state or cleaved bond analog) and the role of the inhibitor side chains from P4 to P4' were investigated. MAV proteinase prefers an aromatic side chain in P1 and a small aliphatic nonpolar chain in P2 and P2'. Residues in P5 and P4 positions are outside of the short catalytic cleft of the enzyme, but still influence binding considerably. The data obtained provide evidence that the MAV proteinase has generally lower specificity and poorer binding than the HIV proteinase.

Amino Acid Sequence↗
PubMed1992

[Folk healing causing severe diabetic coma].

The authors demonstrate on the case of a 21-year-old female diabetic (type I), who had been well compensated with insulin for five years, the life threatening procedure of a popular healer. By eliminating insulin he induced severe keto acidotic coma.

Adult↗
PubMed1992

Reduced-bond tight-binding inhibitors of HIV-1 protease. Fine tuning of the enzyme subsite specificity.

Truncation of a peptide substrate in the N-terminus and replacement of its scissile amide bond with a non-cleavable reduced bond results in a potent inhibitor of HIV-1 protease. A series of such inhibitors has been synthesized, and S2-S3' subsites of the protease binding cleft mapped. The S2 pocket requires bulky Boc or PIV groups, large aromatic Phe residues are preferred in P1 and P1' and Glu in P2'. The S3' pocket prefers Phe over small Ala or Val. Introduction of a Glu residue into the P2' position yields a tight-binding inhibitor of HIV-1 protease, Boc-Phe-[CH2-NH]-Phe-Glu-Phe-OMe, with a subnanomolar inhibition constant. The relevant peptide derived from the same amino acid sequence binds to the protease with a Ki of 110 nM, thus still demonstrating a good fit of the amino acid residues into the protease binding pockets and also the importance of the flexibility of P1-P1' linkage for proper binding. A new type of peptide bond mimetic, N-hydroxylamine -CH2-N(OH)-, has been synthesized. Binding of hydroxylamino inhibitor of HIV-1 protease is further improved with respect to reduced-bond inhibitor.

Amino Acid Sequence↗
PubMed1992

Mutagenic activity of copper(II) chromate and dichromate complexes with polypyridines.

Copper(II) chromate and dichromate complexes with 2,2'-bipyridyl and 1,10-phenathroline were tested for their mutagenic activity in the standard Ames test. All of six tested complexes exhibited markedly lower mutagenic activity than the reference compounds--potassium dichromate and sodium chromate. The blockage of Cr(VI) reduction capability in the presence of the complex Cu2+ ion and the competition between copper and chromium ions in the interaction with cellular components are discussed in the light of the results of our previous chemical study.

2,2'-Dipyridyl↗
PubMed1992

Resistance to Ascaris suum in parasite naïve and naturally exposed growers, finishers and sows.

Commercially reared growers, finishers, and sows of Danish Landrace x Yorkshire crossbred were inoculated orally with Ascaris suum at 50 eggs kg-1 body weight. White spots on the serosal surface of livers and total larval recoveries from lungs were recorded 7 days later. The response in pigs originating from a specific pathogen free and parasite free herd (parasite naïve) was observed in the three different age groups and compared with age-matched pigs from a herd maintained in a facility contaminated with A. suum (naturally exposed). The pre-inoculation immune status of the various groups was characterized serologically using antigen preparations derived from various stages of A. suum. Inoculation of all age groups of parasite naïve pigs with A. suum eggs produced relatively high liver white spots and lung larvae, although expression of these counts as a percentage of the inoculum showed a moderate age-related resistance from growers to finishers to sows. In contrast, pigs naturally exposed to A. suum expressed strong immunity to a challenge infection as few or no larvae were detected in the lungs. In addition, growers, finishers, and sows from the naturally exposed herd had significantly higher levels of serum IgG/IgA to several different A. suum antigens compared with pigs from the parasite nave herd. Liver white spots, expressed as a percentage of the inoculum, were highest in growers from the naturally exposed herd but were markedly reduced in finishers and sows from that herd. In fact, few or no white spots were observed in naturally exposed sows, while sows from the parasite-naïve herd had in excess of 300 liver white spots following challenge. These results indicate that commercially raised pigs that are exposed to A. suum develop a strong protective immunity that ultimately produces a complete pre-hepatic barrier to larval migration, while pigs raised parasite free remain susceptible to infection.

Age Factors↗
PubMed1992

Influence of the pH-value on the growth of Staphylococcus epidermidis, Staphylococcus aureus and Propionibacterium acnes in continuous culture.

A cutaneous isolate of Staphylococcus epidermidis, Staphylococcus aureus and Propionibacterium acnes was grown in continuous culture at varying pH-values ranging from 5.0 to 8.5. In terms of the specific growth rate as well as the bacterial density during the plateau phase there were remarkable differences. In particular, Propionibacterium acnes grew much better in the pH 6.0 to 7.0 range than in a more acidic or alkaline milieu. Staphylococcus epidermidis resembled Staphylococcus aureus showing no major difference at pH 5.5 and 7.0. These findings substantiate the hypothesis that minor changes of the pH in the pH 5.5 to pH 6.0 range as to be induced by chemically neutral or alkaline skin cleansers on the human skin surface can increase the number of propionibacteria but not staphylococci remarkably due to the relative alkalinity by itself.

Culture Media↗
PubMed1991

Purified Fc epsilon R+ bone marrow and splenic non-B, non-T cells are highly enriched in the capacity to produce IL-4 in response to immobilized IgE, IgG2a, or ionomycin.

Non-B, non-T cells from spleen and bone marrow cells produce IL-4 in response to cross-linkage of high affinity receptors for Fc epsilon R or Fc gamma RII, and to treatment with calcium ionophores. Cells bearing high affinity Fc epsilon R constituted 1 to 2% of non-B, non-T cells of spleen and of total bone marrow cells from naive donors. In mice whose immune systems had been polyclonally activated by injection with anti-IgD antibodies or had been infected with Nippostrongylus brasiliensis larvae, the frequency of Fc epsilon R+ cells in splenic non-B, non-T cells was also 1 to 2% but in bone marrow from anti-IgD-injected mice donors the frequency was approximately 5%. Cell sorting experiments revealed that all of the capacity to produce IL-4 in response to immobilized IgE or IgG2a or to ionomycin was found in the Fc epsilon R+ fraction. Among the Fc epsilon R+ spleen cells from naive donors, the frequency of IL-4-producing cells was 1/20 to 1/40 whereas in mice that had been injected with anti-IgD or infected with N. brasiliensis, the frequency of IL-4 producing cells in the Fc epsilon R+ population was approximately 1/5.

Animals↗
PubMed1991

Molecular cloning of gp 80, a glycoprotein complex secreted by kidney cells in vitro and in vivo. A link to the reproductive system and to the complement cascade.

cDNA clones coding for the gp 80 heterodimeric glycoprotein complex secreted constitutively at the apical surface of Madin-Darby canine kidney (MDCK) cells have been isolated from MDCK cDNA libraries in lambda gt11 and lambda gt10. The cloned sequences encode a polypeptide chain of 445 amino acids. The deduced amino acid sequence of the gp 80 protein reveals 80% homology to rat SGP-2, a major secretory protein of the testes epithelium and 83% homology to SP-40,40, a human complement-associated protein. SGP-2 and SP-40,40 have been proposed to be serum and seminal forms of the same protein. The sequence homology as well as the results of Southern and Northern blot analyses and immunological studies suggest that gp 80 is the canine homolog of the rat SGP-2 and the human SP-40,40. The protein is expressed in the embryonic kidney already early during organogenesis. In the adult kidney the protein has been localized along the luminal surfaces of the proximal and distal tubule and the collecting duct cells.

Amino Acid Sequence↗
PubMed1991

Increased frequency of interleukin 4-producing T cells as a result of polyclonal priming. Use of a single-cell assay to detect interleukin 4-producing cells.

A limiting dilution assay capable of detecting interleukin 4 (IL4) production by a single cell has been developed. This assay is based on the stimulation of T cells, in the presence of IL2 (5 U/ml), with anti-CD3 antibody bound to the surface of Terasaki wells. Cells of the IL4-selective indicator line, CT.4S, are added 24-36 h later and IL4 production is determined based on their survival 24-48 h thereafter. A frequency of 0.98 was obtained for IL4 production by T cells of the D10.G4 cell line. T cells from naive donors capable of producing IL4 in response to anti-CD3 plus IL2 were quite rare, with a frequency in four experiments ranging between 0.0003 and 0.0018. Treatment of mice with polyclonal activators known to increase the IL 4-producing capacity of T cells when assayed in bulk culture caused striking increases in the frequency of IL4-producing cells. Similarly, culturing cells in vitro with anti-CD3, IL2 and IL4 for 5 days caused a marked increase in the frequency of cells capable of producing IL4, to 0.031.IL4 production by individual T cells is dependent upon IL2. Thus, in naive T cell populations, the frequency of IL4-producing cells in response to stimulation with anti-CD3 in the absence of IL2 was below the limit of detection. T cells from primed donors showed a striking inhibition in the frequency of IL4-producing cells in response to anti-CD3 when IL2 was not present. The availability of a simple assay to measure the frequency of cells capable of producing IL4 should have substantial utility in allowing the evaluation of conditions that regulate IL4 production in vivo and in vitro.

Animals↗
PubMed1990

Cord blood triglyceridemia in cases of placental insufficiency.

Cord blood triglyceride concentration increased in cases of placental insufficiency. The significant relationship has been found between elevated triglyceride, decreased Apgar score, and low pH values. We suggest that the measurement of cord blood triglyceridemia might be used as a valuable indicator of chronic fetal distress.

Apgar Score↗
PubMed1990

[Contribution of the treatment of discoloured teeth].

New dental materials and their combinations increase the aesthetic and functional quality of treatment. A great improvement in the aesthetic treatment of discoloured teeth is the use of dental ceramic combined with composites.

Ceramics↗
PubMed1990

[Weight reduction in obese patients in the early period after myocardial infarct].

During the early rehabilitation stage to 27 obese subjects after a non-complicated myocardial infarction a low energy diet was administered (2 and 5 MJ resp.--19 patients) or diet no. 7 or 9 (9 and 6 MJ--8 patients). The regime was started on average 8.4 days (at least 5 days) after the acute attack, its tolerance was satisfactory, there were no complications. In the group with a markedly low energy diet the cholesterol and total lipid levels declined. The body weight declined in both groups. It was revealed that early body weight reduction in obese subjects with non-complicated myocardial infarction involves no risk and the hospitalization period can be effectively used also as introduction to the regime in secondary prevention of ischaemic heart disease.

Diet, Reducing↗
PubMed1989

Umbilical cord gamma-glutamyl transpeptidase and placental dysfunction.

Placental dysfunction has been suspected if human placental lactogen level and/or cystine-aminopeptidase activity were lower than 10th centile. Significant rise in gamma-glutamyl transpeptidase (GGTP) has been found in samples of arterial cord blood of newborns born to mothers with placental insufficiency. We observed the relationship between GGTP activity and decrease in cord pH and lower Apgar score of corresponding infants. We suggest that chronic hypoxemia as a consequence of placental dysfunction may result in damage of fetal liver cells.

Apgar Score↗
PubMed1989

Acid-base status of the newborn in relation to cord blood serum creatine kinase isoenzymes' activities.

Creatine kinase (CK) isoenzymes are considered to be specific tissue injury markers. The purpose of this study was to evaluate CK isoenzymes (CK-MM, CK-MB, and CK-BB) in umbilical cord blood sera of newborns in relation to their acid-base status. Investigations were performed in a group of 75 newborns delivered after 37 weeks of pregnancy. We estimated CK-isoenzymes with the use of DEAE-Sepharose C1-6B column chromatography. Total CK activity was measured using kits supplied by Boehringer-Mannheim (Monotest-R CK-NAC aktiviert). Newborns were considered hypoxic if umbilical artery blood pH was under 7.2 and/or base excess less than -10 mmol/L. Of 75 newly born infants 26 had features of perinatal hypoxia. We were unable to demonstrate significant differences in total CK, CK-MM and CK-MB activities in examined groups of newborns. We found a significant rise of CK-BB activity in cord sera of hypoxic infants. Our results show that the fetal brain is the most vulnerable to a hypoxic state.

Acid-Base Equilibrium↗
PubMed1987

Constitutive apical secretion of an 80-kD sulfated glycoprotein complex in the polarized epithelial Madin-Darby canine kidney cell line.

The biosynthesis, processing, and apical secretion of a group of polypeptides (Kondor-Koch, C., R. Bravo, S. D. Fuller, D. Cutler, and H. Garoff. 1985. Cell. 43:297-306) are studied in MDCK cells using a specific polyclonal antiserum. These polypeptides are synthesized as a precursor protein which has an apparent Mr of 65,000 in its high mannose form. This precursor is converted into a protein with an apparent Mr of 80,000 containing complex carbohydrates and sulfate. After intracellular cleavage of the 80-kD protein, the 35-45-kD subunits are secreted as an 80-kD glycoprotein complex (gp 80) linked together by disulfide bonds. Secretion of the protein complex occurs by a constitutive pathway at the apical surface of the epithelial monolayer. Since the immediate post-translational precursor, the 65-kD protein, is hydrophilic in nature as shown by its partitioning behavior in a phase-separated Triton X-114 solution, gp 80 is segregated into the apical exocytotic pathway as a soluble molecule. The proteolytic maturation of gp 80 is blocked in the presence of chloroquine and its secretion is retarded. The 80-kD precursor is released at the apical cell surface, demonstrating that proteolytic processing is not necessary for the apical secretion of this protein. If N-glycosylation is inhibited by tunicamycin treatment the protein is secreted in equal amounts at both cell surfaces, indicating a role of the carbohydrate moieties in the vectorial transport of this protein.

Animals↗
PubMed1986

Mechanical and biochemical properties of human articular cartilage in osteoarthritic femoral heads and in autopsy specimens.

We studied the mechanical and biochemical properties of articular cartilage from 22 osteoarthritic femoral heads obtained at operation and 97 femoral heads obtained at autopsy. Cartilage from the zenith and from the antero-inferior aspect of each head was tested both in tension and in compression. Water content, swelling ability and proteoglycan content were measured, the cartilage was examined histologically and the density of the underlying bone was assessed. Fifty-five of the autopsy specimens were defined as macroscopically normal because they exhibited no progressive fibrillation patterns on staining with Indian ink; but significant changes in water content, bone density and tensile strength related to age were seen in this group. In 20 pairs of femoral heads which were both macroscopically normal, we found, surprisingly, that cartilage from the left and right sides of the same patient was sometimes very different. Compared with the normal autopsy specimens the osteoarthritic specimens had a significantly increased swelling ability, a lower proteoglycan content and impaired mechanical properties, being both weaker in tension and softer in compression. Abnormal autopsy specimens had values intermediate between those of osteoarthritic and normal groups. Results from this abnormal group suggest that there is no primary loss of proteoglycan in early osteoarthritis.

Adolescent↗