Biomedical subjects

S Weigel

Publications and source records attributed to S Weigel.

8 recordsLinked to original sources

PubMed2000

The nuclear export signal within the E4orf6 protein of adenovirus type 5 supports virus replication and cytoplasmic accumulation of viral mRNA.

During the late phase of adenovirus infection, viral mRNA is efficiently transported from the nucleus to the cytoplasm while most cellular mRNA species are retained in the nucleus. Two viral proteins, E1B-55 kDa and E4orf6, are both necessary for these effects. The E4orf6 protein of adenovirus type 5 binds and relocalizes E1B-55 kDa, and the complex of the two proteins was previously shown to shuttle continuously between the nucleus and cytoplasm. Nucleocytoplasmic transport of the complex is achieved by a nuclear export signal (NES) within E4orf6. Mutation of this signal sequence severely reduces the ability of the E1B-55 kDa-E4orf6 complex to leave the nucleus. Here, we examined the role of functional domains within E4orf6 during virus infection. E4orf6 or mutants derived from it were transiently expressed, followed by infection with recombinant adenovirus lacking the E4 region and determination of virus yield. An arginine-rich putative alpha helix near the carboxy terminus of E4orf6 contributes to E1B-55 kDa binding and relocalization as well as to the synthesis of viral DNA, mRNA, and proteins. Further mutational analysis revealed that mutation of the NES within E4orf6 considerably reduces its ability to support virus production. The same effect was observed when nuclear export was blocked with a competitor. Further, a functional NES within E4orf6 contributed to the efficiency of late virus protein synthesis and viral DNA replication, as well as total and cytoplasmic accumulation of viral late mRNA. Our data support the view that NES-mediated nucleocytoplasmic shuttling strongly enhances most, if not all, intracellular activities of E4orf6 during the late phase of adenovirus infection.

Adenovirus E1A Proteins↗

PubMed1999

P(2)O, the Phosphorus Analogue of N(2)O, as a Ligand in a Tetranuclear Cluster.

The first complex to contain the N(2)O analogue P(2)O as a ligand is the tetranuclear cluster [{Cp*Fe}{Cp"Co}(3)(P(2)O)(PO)(P(2))] (1), which is formed by the oxidation in air of [{Cp*Fe}{Cp"Co}(2)(P(4))(P)] (Cp*=C(5)Me(5); Cp"=1,3-tBu(2)C(5)H(3)). The bent P(2)O ligand is doubly side-on as well as terminally coordinated (sigma,sigma,pi,pi) to the four metal atoms (see picture). In addition, 1 contains a PO and a P(2) ligand.

Journal Article↗

PubMed1998

Inactivation of p53 but not p73 by adenovirus type 5 E1B 55-kilodalton and E4 34-kilodalton oncoproteins.

The adenovirus E1B 55-kDa and E4 34-kDa oncoproteins bind and inactivate the p53 tumor suppressor gene product, resulting in cell transformation. A recently discovered cellular protein, p73, shows extensive similarities to p53 in structure and function. Here we show that the simultaneous transient expression of E1B 55-kDa and E4 34-kDa proteins is sufficient to drastically shorten the intracellular half-life of p53, leading to strongly reduced steady-state p53 levels. Concomitantly, the E1B 55-kDa and E4 34-kDa proteins act synergistically to inactivate the transcriptional activity of p53. Mutational analysis suggests that physical interactions between the E1B 55-kDa protein and p53 and between the E1B 55-kDa and E4 34-kDa proteins are both required for p53 degradation. In contrast, the ability of p53 to interact with the cellular mdm2 oncoprotein or with its cognate DNA element appears to be dispensable for its destabilization by adenovirus gene products. The adenovirus E1B 55-kDa protein did not detectably interact with p73 and failed to inhibit p73-mediated transcription; also, the E1B 55-kDa and E4 34-kDa proteins did not promote p73 degradation. When five amino acids near the amino termini were exchanged at corresponding positions between p53 and p73, this rendered p53 resistant and p73 susceptible to complex formation and inactivation by the E1B 55-kDa protein. Our results suggest that while p53 inactivation is a central step in virus-induced tumor development, efficient transformation can occur without targeting p73.

Adenovirus E1B Proteins↗

PubMed1998

Schizophrenia-specific basic symptoms. A successful replication.

Several investigations showed that the Frankfurt Complaint Questionnaire (FCQ) has no diagnostic specificity. However, in a preceding study two new FCQ subscales were developed: FCQ-S, sensitive to schizophrenia, and FCQ-A, sensitive to alcoholism. The aim of the present study was to replicate the diagnostic sensitivity of those subscales. Four groups were considered: schizophrenics with marked negative symptoms (n = 25); schizophrenics with no or mild negative symptoms (n = 25); alcoholics (n = 25); patients with obsessive-compulsive disorder (n = 15). FCQ original subscales and total score did not differ between groups. As expected, in FCQ-S both schizophrenic groups had significantly higher scores than the other groups; FCQ-A failed to show group differences but was significantly related to alcoholism markers.

Adult↗

PubMed1986

Hypoglycemia following insulin and proinsulin. A comparison.

The counterregulatory hormonal response to proinsulin-induced hypoglycemia was investigated in eight volunteers. Proinsulin cleared slower from the circulation than insulin. Hypoglycemia occurred slower (2P less than 0.005) and was prolonged, while the overall hypoglycemic activities were comparable. The antilipolytic effect of proinsulin was also prolonged (2P less than 0.001). The response of epinephrine to hypoglycemia was less pronounced after proinsulin (2P less than 0.05). The amount of epinephrine was correlated to the rate of fall in plasma glucose (P less than 0.005). The production of lactate induced by beta-stimulation was also correlated to the fall of glucose (P less than 0.005). The responses of prolactin (2P less than 0.02), norepinephrine (2P less than 0.02), cortisol, and growth hormone were attenuated following proinsulin. The decreases of serum potassium and serum phosphate (2P less than 0.05) were less pronounced. Symptoms like sweating (2P less than 0.01) and dizziness (2P less than 0.01) were milder after proinsulin. It is concluded that the rate of fall in glucose concentration determines the differing counterregulatory responses. We don't relate the differing counterregulatory responses to special insulin-like properties of proinsulin, but to the slower kinetics which is emphasized by the intravenous bolus injection.

3-Hydroxybutyric Acid↗

PubMed1985

Postnatal methyl mercury exposure: effects on ontogeny of renal and hepatic ornithine decarboxylase responses to trophic stimuli.

The effects of postnatal methyl mercury exposure on the ontogeny of renal and hepatic responsiveness to trophic stimuli were examined. Increased ornithine decarboxylase (ODC) activity was used as an index of tissue stimulation. In the rat, renal ODC responsiveness to growth hormone, angiotensin, vasopressin, isoproterenol, and serotonin was absent at birth and matured 3 to 4 weeks later. However, pups exposed to methyl mercury showed marked, ODC responses to these same agents as early as 10 to 19 days of postnatal age, accompanied by a significant renal hypertrophy. In contrast to the kidney, the liver of normally developing rats was responsive to trophic factors even in the neonate. In this tissue, there was no consistent effect of neonatal methyl mercury treatment on ODC responses at any developmental stage tested; although absolute liver weights were reduced, liver/body weight ratio was not affected. These results demonstrate that postnatal methyl mercury exposure causes a precocious onset of ODC responses to trophic agents specifically in the kidney. Altered responsiveness may mediate some of the effects of this organomercurial on overall renal development and function.

Animals↗

PubMed1982

Organ specificity of neonatal methyl mercury hydroxide poisoning in the rat: effects of ornithine decarboxylase activity in developing tissues.

To determine the organ specificity of neonatal mercury hydroxide (CH3HgOH) exposure on biochemical development of its potential target tissues, effects on rat brain, liver, heart and kidney were compared utilizing the ontogenetic pattern of ornithine decarboxylase (ODC) activity, an early index of perturbation of cellular maturation. CH3HgOH was given daily beginning at birth for up to 21 days, using three dose levels (1, 2.5 or 5 mg/kg s.c.). In the brain, CH3HgOH treatment resulted in an initial reduction in ODC followed by a subsequent elevation of activity, a maturational pattern known to be associated with delayed cellular development. In contrast to the effects of CH3HgOH on brain, the pattern obtained in the liver, an initial elevation followed by a subsequent decline, is usually associated with compression of the time couse of cellular development. In the heart and kidney, CH3HgOH produced sustained elevations of ODC representing prolongation of the developmental period of rapid tissue growth and development; these patterns were associated with tissue hypertrophy which was sustained through the preweaning stage for both tissues and well into the postweaning period for the kidney. The results obtained with ODC clearly demonstrate that neonatal CH3HgOH poisoning causes organ-specific biochemical lesions which can play a role in subsequent effects on overall tissue development.

Aging↗

PubMedDate not supplied

Antibiotic sequential therapy for febrile neutropenia in pediatric patients with malignancy.

Children suffering malignant diseases can experience phases of bone marrow depression during intensive chemotherapy. The influence of antibiotic sequence therapy on the course of diseases was examined in 41 pediatric patients with malignant diseases. Inclusion criteria were neutropenia (ANC < 500/microL), rectal body temperature over 38.5 degrees C, and increased C-reactive protein (CRP, cutoff > 5.0 mg/L). The first stage of therapy comprised the following antibiotics: piperacillin, teicoplanin, and gentamicin. In stage 2 imipenem, teicoplanin, and tobramycin were administered. Fluconazole was the antifungal drug of choice in stages 1 and 2. In the first level of antibiotic therapy 68% of the patients showed a positive reaction. The C-reactive protein was a sensitive parameter, which significantly decreased with 3 days of therapy. A total of 72% of the bacteriological smears were sterile. All patients survived the septic phase.

Adolescent↗