Search PubMed⌕ Search

Biomedical subjects

I Schmidt

Publications and source records attributed to I Schmidt.

At least 19 recordsLinked to original sources
PubMed2000

The homeodomain of Nkx2.2 carries two cooperatively acting nuclear localization signals.

NK-2 family members of homeodomain proteins have been identified as important regulators of growth and development in the ventral forebrain, heart, lung, and thyroid. In addition, Nk2.2 expression has been detected in the pancreas, where it is vital for the final differentiation of beta-cells. In our present paper, we have analyzed the domains necessary for nuclear transport of Nkx2.2. With the help of deletion mutants we identified two separate nuclear localization signals (NLS). Interestingly, both NLSs are situated in the homeodomain. They belong to the monopartite class of NLS; the proximal NLS has the sequence KKRKRR and lies at the very N-terminus of the homeodomain, while the more distal NLS RYKMKRAR is at the homeodomain C-terminus. Each NLS per se is sufficient for nuclear transport of Nkx2.2 into the nucleus, although inefficiently. Both identified NLSs act cooperatively in mediating complete nuclear transport of Nkx2.2.

Amino Acid Sequence↗
PubMed2000

[The Marjolin's ulcer": a malignant and rarely complication after burn trauma of the upper extremity - a case report].

The,Marjolin's ulcer" is a malignant lesion which is developed especially at chronic wounds after burn trauma. The latency from primary trauma to the malignant transformation is about 30 years. The lesion is more aggressive than other squamous cell carcinomas. We report on the combined radiation and surgical therapy of an 65-year-old patient with this lesion on the right hand and regional lymph node metastases. The extensive tissue defect after wide excision was reconstructed with a reversal radial forearm flap.

Aged↗
PubMed2000

Significance of gaseous NO for ammonia oxidation by Nitrosomonas eutropha.

Nitrification by the obligately lithoautotrophic ammonia oxidizer Nitrosomonas eutropha was significantly inhibited when nitric oxide was removed from the culture medium by means of intensive aeration and turbulence. Nearly complete recovery of ammonia oxidation could be achieved by adding 100 ppm NO to the supplied air. Inhibition of ammonia oxidation occurred also upon addition of the NO binding agent 2,3-Dimercapto-1-propane-sulfonic acid (DMPS). Recovery of ammonia oxidation occurred within 3 h in the presence of 100 ppm NO and within 76 h in the absence of externally added NO. In co-cultures of N. eutropha and the NO detoxifying bacterium Pseudomonas PS88, hardly any nitrification was detectable and release of NO was extremely low when the heterotroph was provided with an organic substrate. When cells of Pseudomonas PS88 were added to a mixotrophically nitrifying culture of N. eutropha the release of NO decreased drastically upon the addition and ammonia oxidation ceased. These results confirm for the first time the significance of NO in the course of ammonia oxidation by N. eutropha.

Ammonia↗
PubMed1999

Safety issues for plasma derivatives and benefit from NAT testing.

Manufacturing processes for plasma derivatives are in general highly effective for removal or inactivation of enveloped viruses and the products are safe with regard to the clinically important viruses HIV, HCV and HBV. They are not so effective for the elimination for non-enveloped viruses, especially Parvovirus B19 (B19). A certain risk remains of B19 contamination for some plasma derivatives that is caused, firstly, by the occurrence of highly contaminated donations (up to 10(14)genomes/ml) and secondly, by the extreme heat resistance and small size of B19 which makes it difficult to remove or inactivate. NAT is a beneficial tool for detection of virus contamination. It is routinely used for the detection of HCV-RNA in plasma pools, thereby preventing the processing of HCV-RNA positive material. NAT assays may also be valuable for testing the removal of viruses during manufacturing. This may be especially important if a virus cannot be tested by infectivity assays.

Blood Donors↗
PubMed1999

Mutation in the leptin receptor (Leprfa) causes fat-storage-independent hyperleptinaemia in neonatal rats.

The plasma leptin concentration adjusted for fat mass is affected by mutant gene dosage in older animals segregating for Leprfa. Because the plasma of neonatal rats contains leptin, although their adipocytes contain virtually no triglyceride, we determined whether mutation dose-dependent differences in plasma leptin concentration exist before the postnatal onset of triglyceride storage. Plasma samples were obtained 10 min after birth of each rat pup and leptin concentration determined by radioimmunoassay. Plasma leptin in homozygous wild-type (+/+) pups was 1.6 +/- 0.2 ng/ml (n = 20) and 2.4 +/- 0.2 ng/ml in +/fa (n = 32) littermates (least-square means +/- SE, P < 0.05, two-way ANOVA with litter and genotype as factors). The corresponding values for +/fa (n = 21) and fa/fa (n = 15) littermates were 2.4 +/- 0.2 and, 4.0 +/- 0.3 ng/ml respectively (P < 0.001). Leprfa gene dose-dependent elevations in plasma leptin are, therefore, present at birth and constitute the only Leprfa-related phenotypic trait presently known to precede the onset of increased fat storage.

Animals↗
PubMed1999

Development of vasomotor control in lean (+/?) and genetically obese (fa/fa) rat pups.

Using laser Doppler flowmetry, we determined whether vasomotor control is already functional in 7-, 11-, and 16-day-old rat pups, and whether differences in vasomotor responses between 16-day-old lean (+/?) and fatty (fa/fa) pups occur. For 3 h, at the end of their daily light phase, the pups were exposed to 30-min step changes of ambient temperature (Ta) alternating between thermoneutrality and cold loads resulting in a 50-100% increase of metabolic rate (MR) above its thermoneutral value, while core temperature (Tc), skin blood flux at the hindpaw, and MR were recorded. In all age groups, blood flux changed significantly in response to these Ta changes. The time needed for a significant change in blood flux was shorter in the 7-day-old than in the 16-day-old lean pups, while the Ta dependency of Tc was more pronounced in the younger pups. Comparison of the responses of the 16-day-old fatty and lean pups showed a parallel shift to lower values in the correlation of Ta with MR in the fa/fa pups, but no difference in the correlation of Ta with blood flux. This demonstrates that the vasomotor control system in the rat is already functional by the age of 7 days, and that the fa/fa lesion influences the vasomotor control less than the metabolic cold defense.

Animals↗
PubMed1999

The nuclear localization signal (NLS) of PDX-1 is part of the homeodomain and represents a novel type of NLS.

The beta-cell homeodomain transcription factor PDX-1 has vital functions both in controlling the expression of pancreatic polypeptide hormones and in the development of the pancreas. The transactivating and DNA-binding properties of PDX-1 have been well characterized, but nuclear transport is still undefined. Here we show that PDX-1 bears a nuclear localization signal (NLS) that is part of helix 3 of the homeodomain. PDX-1 deletion mutants were tagged with enhanced green fluorescent protein (EGFP) and expressed in COS-7 cells. Subcellular localization of the respective PDX-1-EGFP fusion proteins was analyzed by direct fluorescence microscopy and Western immunoblotting using an anti-(GFP). As a result we were able to demonstrate that the homeodomain or helix 3 alone was sufficient and necessary for transport into the nucleus. Point mutations of basic amino acid residues within helix 3 led to identification of an NLS with six amino acids being crucial for nuclear transport of PDX-1. Because this NLS does not match known examples of NLSs, the PDX-1 NLS may represent a novel class of NLS.

Amino Acid Sequence↗
PubMed1999

Organization of the motor centres for the innervation of different muscles of the tongue: a neuromorphological study in the frog.

Cobalt labelling studies on the localization and morphology of the frog's hypoglossal nucleus have revealed three subnuclei. The dorsomedial subnucleus innervates the geniohyoid, hyoglossus, genioglossus and the intrinsic tongue muscles. The ventrolateral subnucleus supplies the sternohyoid, geniohyoid, omohyoid and intrinsic tongue muscles. The intermediate subnucleus innervates the omohyoid, geniohyoid and intrinsic tongue muscles. Neurons innervating protractor, retractor and intrinsic tongue muscles differ in their soma surface area and in their dendritic arborization pattern. It is concluded that there exists a musculotopic organization in the frog's hypoglossal nucleus and that motoneurons subserving different function in tongue movements disclose characteristic morphological differences.

Animals↗
PubMed1999

Leptin responsiveness and gene dosage for leptin receptor mutation (fa) in newborn rats.

To determine the degree to which the leptin receptor mutation (fa) influences the responsiveness to leptin during the first postnatal week, we injected recombinant leptin (600 pmol. g-1. day-1 sc from day 1 to day 7) into wild-type (+/+), heterozygous (+/fa), and fatty (fa/fa) rat pups. Growth and final body fat content of these leptin-treated pups were compared with those of saline-treated littermates of the same genotype. The body mass of the leptin-treated +/+ pups, but not that of the +/fa and fa/fa pups, increased more slowly than that of their respective controls, and fat content at day 7 was reduced by 37% in +/+ pups, by 22% in +/fa pups, but not at all in fa/fa pups. Plasma leptin remained excessively high throughout the day under this treatment, but a 30-fold lower leptin dose, causing only moderate changes of plasma leptin, still reduced the body fat of +/+ pups significantly. We conclude that leptin participates in the control of even the earliest stages of fat deposition and that the response to supraphysiological doses of leptin is markedly reduced in 1-wk-old pups with one fa allele and absent in pups with two fa alleles.

Adipose Tissue↗
PubMed1998

Purification and characterization of cytosolic cytochrome P450 forms from yeasts belonging to the genus Trichosporon.

The yeast Trichosporon spec. SBUG 752 isolated from soil produced cytochrome P450 during the stationary phase of growth on glucose. After cell disruption and ultracentrifugation, large amounts of P450 (250 pmol/mg protein) were found in the cytosolic fraction. In contrast, no P450 was detectable in the microsomes. Similar results were also obtained from some other yeast species of the genus Trichosporon. After purification to electrophoretic homogeneity, the P450 from Trichosporon spec. SBUG 752 migrated in SDS-PAGE with an apparent Mr of 43,000. Final purification by isoelectric focusing yielded two different isoenzymes in their spectrally active state-P450TS1 and P450TS2-having pI values of 5.9 and 6.2, respectively. Partial N-terminal amino acid sequencing revealed a high degree of sequence homology between P450TS1 and P450TS2 and their close relationship to the soluble P450 forms of the CYP55 family which are known to act as nitric oxide reductases in some filamentous fungi. The P450TS1 from Trichosporon spec. SBUG 752 catalyzed nitric oxide reduction under anaerobic conditions in an NADH- and NADPH-dependent manner-an activity not yet described for yeasts. These results demonstrate the existence of soluble P450 forms in yeasts exhibiting functional and structural characteristics similar to those of the P450 forms of the CYP55 family.

Amino Acid Sequence↗
PubMed1998

Resident characteristics and organizational factors influencing the quality of drug use in Swedish nursing homes.

Appropriateness of drug use is an important indicator of the quality of care in nursing homes. In this study, we analyzed the influence of resident characteristics and selected organizational factors on the appropriateness of psychotropic drug use in 33 Swedish nursing homes. Specific criteria based on published guidelines and recommendations were developed to measure appropriateness. Residents diagnosed with a psychiatric disorder and younger residents had more deviations from the criteria; however, resident mix did not explain variations in appropriateness of drug use at the facility level. Facilities with better nurse staffing and drug intervention teams had fewer deviations from the criteria, but only 15-20% of the variation in drug prescribing was explained by these predictors.

Aged↗
PubMed1998

Anaerobic ammonia oxidation by cell-free extracts of Nitrosomonas eutropha.

Cell-free extracts of Nitrosomonas eutropha oxidized ammonia to nitrite with NO2 (N2O4) as electron acceptor. The ammonia oxidation activity was shown to be sensitive against oxygen. In the absence of oxygen ammonia and NO2 were consumed in a ratio of approximately 1:2 and hydroxylamine occurred as an intermediate. NO was released in amounts equimolar to the consumption of NO2. After passing the cell suspension through a French pressure cell and fractionating it by density gradient centrifugation using a linear sucrose gradient, two soluble and two membrane fractions were detectable. Highest ammonia oxidation activity was measured in the membrane fractions and highest hydroxylamine oxidation activity in the soluble fractions. The KS values of the ammonia oxidizing system in cell-free extracts was about 20 microns NH3 and remained unchanged between pH 7.25 to 8.25.

Ammonia↗
PubMed1998

Leptin selectively increases energy expenditure of food-restricted lean mice.

OBJECTIVE: To find out whether leptin can attenuate hypometabolic torpor-like states of metabolic rate (MR) in adult lean animals, as it attenuates the morning suppression of thermoregulatory thermogenesis in suckling-age rat pups. DESIGN: Leptin effects on MR and food intake were studied in mice aged 4-7 months, in which a high incidence of exaggerated circadian reductions of MR had been induced by chronic food-restriction and, for comparison, in free-feeding mice. PROTOCOL: Continuous recordings of MR, for a group of seven mice maintained at an ambient temperature of 24 degrees C, while they were repeatedly-with pauses of at least six days-treated for three consecutive days with either recombinant murine leptin (20, 200 or 600 pmol x g(-1) x d[-1]) or saline. RESULTS: Leptin treatment caused dose-dependent 5-15% increases in energy expenditure by moderating the decreases in MR during the circadian minima, without affecting either the MR during the circadian maxima or food intake. Similar treatment of free-feeding mice caused dose-dependent decreases of food intake without changing MR. CONCLUSION: Leptin controls thermoregulatory energy expenditure when food supplies are scarce and changes food intake, rather than energy expenditure, when food is abundant.

Animal Nutritional Physiological Phenomena↗
PubMed1998

Carnitine palmitoyltransferase I (CPT I) activity and its regulation by malonyl-CoA are modulated by age and cold exposure in skeletal muscle mitochondria from newborn pigs.

Whole-body lipid utilization is progressively enhanced during the first postnatal day in pigs, especially during cold exposure and muscular shivering thermogenesis. This study was designed to examine early postnatal changes in fatty acid oxidation potential, carnitine palmitoyltransferase I activity and regulation by malonyl-CoA in skeletal muscle mitochondria isolated from newborn and 5-d-old piglets. At 5 d of life, pigs were maintained for a 4-h period in thermoneutral (30 degreesC) or cold (20 degreesC) conditions. Intermyofibrillar and subsarcolemmal mitochondria were isolated from longissimus dorsi and rhomboïdeus muscles. In subsarcolemmal mitochondria, carnitine palmitoyltransferase I activity increased with age (P < 0.01) and was 80% lower (P < 0.001) than in intermyofibrillar mitochondria. Intermyofibrillar mitochondria had high enzyme activities and fatty acid oxidation potential from birth. The fatty acids 16:0, 18:1(n-9) and 18:2(n-6) were oxidized at a higher rate than 18:0 (-37%) and 8:0 (-55%). Sensitivity of carnitine palmitoyltransferase I to malonyl-CoA inhibition and malonyl-CoA levels decreased by 47% (P < 0.05) and 33% (P < 0.01) with age, respectively. After 4 h of cold exposure, sensitivity of carnitine palmitoyltransferase I to malonyl-CoA was unaffected in the rhomboideus and tended to be greater (P < 0.06) in longissimus dorsi muscle. Malonyl-CoA levels were lower (P < 0.05) in the rhomboideus and were unaffected in longissimus dorsi muscle. These results demonstrate that fatty acid oxidation is effective from birth in isolated intermyofibrillar mitochondria. The postnatal enhancement of fatty acid utilization observed in vivo can be explained, at least in part, by a rise in carnitine palmitoyltransferase I activity in subsarcolemmal mitochondria and a modulation of its activity by malonyl-CoA in intermyofibrillar mitochondria.

3-Hydroxyacyl CoA Dehydrogenases↗
PubMed1998

The impact of regular multidisciplinary team interventions on psychotropic prescribing in Swedish nursing homes.

OBJECTIVE: To evaluate the impact of regular multidisciplinary team interventions on the quantity and quality of psychotropic drug prescribing in Swedish nursing homes. DESIGN: A randomized controlled trial. SETTING: A sample of 33 nursing homes: 15 experimental homes and 18 control homes representing 5% of all Swedish nursing homes. PARTICIPANTS: The sample consisted of 1854 long-term care residents with an average age of 83 years. Seventy percent of the residents were women, and 42% had a documented diagnosis of dementia. An additional 5% had a psychotic disorder, and 7% had a diagnosis of depression. INTERVENTION: Experimental homes participated in an outreach program that was designed to influence drug use through improved teamwork among physicians, pharmacists, nurses, and nurses' assistants. Multidisciplinary team meetings were held on a regular basis throughout the 12-month study period. MEASUREMENTS: Lists of each resident's prescriptions were collected 1 month before and 1 month after the 12-month intervention. Measures included the proportion of residents with any psychotropic drug, polymedicine, and therapeutic duplication and proportion of residents with nonrecommended and acceptable drugs in each psychotropic drug class, as defined by current Swedish guidelines. RESULTS: Baseline results show extensive psychotropic drug prescribing, with the most commonly prescribed drugs being hypnotics (40%), anxiolytics (40%), and antipsychotics (38%). After 12 months of team meetings in the experimental homes, there was a significant decrease in the prescribing of psychotics (-19%), benzodiazepine hypnotics (-37%), and antidepressants (-59%). Orders for more acceptable antidepressants also increased in the experimental homes. In the control homes there was increased use of acceptable antidepressants, but there were no significant reductions in other drug classes. CONCLUSIONS: There is excessive prescription of psychotropic drugs in Swedish nursing homes. Improved teamwork among caregivers can improve prescribing as defined by clinical guidelines.

Aged↗
PubMed1998

Dissociation of the CD4 and CXCR4 binding properties of human immunodeficiency virus type 1 gp120 by deletion of the first putative alpha-helical conserved structure.

To evaluate conserved structures of the surface gp120 subunit (SU) of the human immunodeficiency virus type 1 (HIV-1) envelope in gp120-cell interactions, we designed and produced an HIV-1 IIIB (HXB2R) gp120 carrying a deletion of amino acids E61 to S85. This sequence corresponds to a highly conserved predicted amphipathic alpha-helical structure located in the gp120 C1 region. The resultant soluble mutant with a deleted alpha helix 1 (gp120 DeltaalphaHX1) exhibited a strong interaction with CXCR4, although CD4 binding was undetectable. The former interaction was specific since it inhibited the binding of the anti-CXCR4 monoclonal antibody (12G5), as well as SDF1alpha, the natural ligand of CXCR4. Additionally, the mutant gp120 was able to bind to CXCR4(+)/CD4(-) cells but not to CXCR4(-)/CD4(-) cells. Although efficiently expressed on cell surface, HIV envelope harboring the deleted gp120 DeltaalphaHX1 associated with wild-type transmembrane gp41 was unable to induce cell-to-cell fusion with HeLa CD4(+) cells. Nevertheless, the soluble gp120 DeltaalphaHX1 efficiently inhibited a single round of HIV-1 LAI infection in HeLa P4 cells, with a 50% inhibitory concentration of 100 nM. Our data demonstrate that interaction with the CXCR4 coreceptor was maintained in a SUgp120 HIV envelope lacking alphaHX1. Moreover, in the absence of CD4 binding, the interaction of gp120 DeltaalphaHX1 with CXCR4 was sufficient to inhibit HIV-1 infection.

Amino Acid Sequence↗