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Biomedical subjects

B Schmitt

Publications and source records attributed to B Schmitt.

At least 91 records · Page 5Linked to original sources
PubMed1997

[Receptor mediated gene transfer in squamous epithelial carcinoma of the head-neck area].

BACKGROUND: The "Adeno-Virus-Enhanced-Receptor-Mediated" (AVET)-System uses the receptor-mediated endocytosis route to introduce DNA into mammalian cells. By the help of a replication defective adenovirus with endosomolytic activity the coentry of receptor-bound DNA particles is faciliated. The transport to the nucleus followed by gene expression is multifold enhanced. METHODS: Two different permanent cell lines from head and neck squamous cell cancer were transfected with the reportergene for luciferase with either AVET or different liposoms in vitro. RESULTS: In comparison it becomes obvious, that AVET shows a multifold higher transfection rate in vitro than the liposomal formulations applied. CONCLUSIONS: AVET could be used for efficient transfection of epithelial cells, that are fairly reluctant to DNA transfer. Further trials in the mouse model must prove a possible application in vivo.

Adenoviruses, Human↗
PubMed1997

Semiquantitative analysis of human papillomavirus DNA in cervical intraepithelial neoplasia by a differential polymerase chain reaction.

A differential polymerase chain reaction (PCR), which takes account of both the human papillomavirus (HPV) type and the amount of viral DNA, was applied to 100 cervical intraepithelial neoplasias (CIN) in order to improve the characterisation of the lesions. One hundred women with cytological smears suggestive of CIN I-III and a colposcopically guided punch biopsy were studied. DNA was phenol-extracted and a consensus PCR with L1 primers and a type-specific PCR for HPV-16 and-18 E6 were performed in parallel. The different sensitivity of the PCR methods allowed a semiquantitative analysis of viral DNA. HPV analysis was possible in all 100 very small cervical punch biopsies. Of the lesions 79% were HPVpositive. The percentage of HPV-16-positive lesions increased significantly (P < 0.001) with the degree of severity of CIN (CIN I: 46%, CIN II: 63%, CIN III: 85%). The percentage of CIN with a high viral load increased also with the grade of CIN (CIN I: 8%, CIN II: 33%, CIN III: 44%). Cytologically positive lesions (Pap IIID or IVa) had significantly more frequently (p < 0.02) a high viral load: 39% vs. 10% of cytologically false negative lesions. In conclusion, type-specific PCR had a very high sensitivity in the detection of HPV-DNA also in cytologically false negative CIN. The addition of the less sensitive consensusPCR allowed a semiquantitative analysis of the viral copy number. The higher amount of viral DNA in cytologically positive lesions, which may correspond to a higher rate of proliferation, reflects a possible role of the viral load in the progression of CIN. In clinical practice, differential HPVPCR could help to improve the management of CIN.

Journal Article↗
PubMed1997

Identification of cytoplasmic subdomains that control pH-sensing of the Na+/H+ exchanger (NHE1): pH-maintenance, ATP-sensitive, and flexible loop domains.

To precisely identify the cytoplasmic subdomains that are responsible for the intracellular pH (pHi)-sensitivity, ATP depletion-induced inhibition and Ca2+ activation of the Na+/H+ exchanger (NHE1), we generated a set of deletion mutants of carboxyl-terminated cytoplasmic domain and expressed them in the exchanger-deficient cell line PS120. We evaluated pHi-sensitivity of these mutants by measuring the resting pHi in cells placed in an acidic medium (pH 6.0) and pHi-dependence of 5-(N-ethyl-N-isopropyl)amiloride-sensitive 22Na+ uptake. Detailed analysis revealed that the cytoplasmic domain of NHE1 is consists of at least four subdomains in terms of pHi-sensitivity of the unstimulated NHE1: I, aa 516-590/595; II, aa 596-635; III aa 636-659; and IV, aa 660-815. Subdomains II and IV were silent for pHi-sensitivity. Subdomain I had a pHi-maintenance function, preserving pHi-sensitivity in a physiological range, whereas subdomain III, overlapping with the high affinity calmodulin (CaM)-binding site, exhibited an autoinhibitory function. Deletion of subdomain I abolished the decrease of pHi-sensitivity induced by cell ATP depletion, indicating that domain I plays a crucial role in this phenomenon. Deletion of subdomain III rendered the inhibition by ATP depletion less efficient, suggesting the possible interaction between subdomains I and III. On the other hand, tandem elongation of subdomain II by insertion did not affect either the inhibitory function of domain III or the removal of this inhibition by ionomycin or thrombin. However, deletion of subdomain II partially abolished the inhibitory effect of subdomain III. Subdomain II thus seems to function as a mobile "flexible loop," permitting the CaM-binding subdomain III to exert its normal function. These findings, together with our previous data, support a concept that cell ATP, Ca2+, and growth factors regulate NHE1 via a mechanism involving direct or indirect interactions of specific cytoplasmic subdomains with the "H(+)-modifier site.".

Adenosine Triphosphate↗
PubMed1997

Benign focal epileptiform discharges in children after severe head trauma: prognostic value and clinical course.

PURPOSE: To assess the occurrence and prognosis of benign focal epileptiform discharges (BFED) in EEG after severe head trauma (SHT) in children. METHODS: Between January 1987 and December 1994, 47 of 828 children with anamnestic SHT showed a single or dominant epileptic focus in EEG. Spike wave localization and morphology were either suggestive for BFED (group I, 21 children) or were suspected to be symptomatic (group II, 26 children). We analyzed the course of epilepsy and epileptic discharges in EEG, neuroradiologic findings, neurologic outcome, and school adjustment. RESULTS: After SHT, spike waves appeared immediately (within 72 h) or delayed (maximum 7 years) and disappeared between ages 3 and 14 years in 14 children of group I and between ages 8 and 23 years in 10 of group II. Children with persistent spike waves in group I were all younger than 14 years; in group II, seven were older than 15 years. Computed tomographic (CT) lesions, ipsilateral to the epileptic focus, were seen in 10 children of group I and 15 of group II. Early seizures occurred in nine children of group I and eight of group II and late-onset seizures in one of group I and nine of group II (p = 0.028). Epilepsy developed in three children of group I and 12 of group II and was drug refractory in six children of group II, all with persistent epileptic foci. Regular schools were attended by 14 (67%) children in group I and 12 (48%) of group II. CONCLUSIONS: Benign focal epileptiform discharges in posttraumatic EEGs have the same favorable prognosis as in benign focal epilepsy and should be handled as recommended for classic benign focal epilepsy.

Adolescent↗
PubMed1997

[Sudden loss of consciousness in childhood].

Sudden loss of consciousness in childhood presents itself usually as a syncope and occurs in approximately 15% of all children. Although syncope in the pediatric age group appears to be an isolated phenomenon with good prognosis, it could also be a manifestation of a life-threatening disease. Thus, even the first syncope should be evaluated in children. A thorough history and a careful physical examination with special attention to cardiovascular and neurologic abnormalities usually point to the etiology of the syncope and must result in the appropriate laboratory tests. About 50% of pediatric syncopes are non-cardiovascular, 20 to 30% are cardiovascular, and 20 to 30% are of unknown etiology. The most frequent syncope in childhood is neurocardiogenic. It is important to distinguish neurocardiogenic syncope from cardiac syncope and epileptic seizures. Neurocardiogenic and cardiac syncopes can be discriminated from epileptic seizures by their usually shorter duration of unconsciousness and rare postsyncopal disorientation. Cardiac syncope is rare in children with a structurally normal heart and may be associated with Wolff-Parkinson-White syndrome, long QT syndrome or congenital AV block. Children with congenital heart defects and cardiomyopathies who present with syncope must raise a high degree of suspicion for a cardiac syncope. Cardiac syncopes often yield a poor prognosis with substantial percentages of sudden death; therefore, a vigorous attempt has to be made to diagnose and adequately treat cardiac syncope in children.

Child↗
PubMed1996

[Limiting costs of implanted defibrillators].

The use of implanted defibrillators is increasing recently. In view of the costs of a gadget, which amount to DM 40,000 to 45,000, arises the questions which juridical requirement have to exist, that after the death of a patient it is possible to reuse a still functional defibrillator. The solution should be that the health insurance keeps the property, whereas the patient receives merely the defibrillator as loan.

Cost Savings↗
PubMed1996

Structure and activity of a chimeric interleukin-8-melanoma-growth-stimulatory-activity protein.

A 72-amino-acid chimeric protein, Chi1, was constructed from the N-terminal part of interleukin 8, IL-8-(1-53), and the C-terminal part of melanoma growth stimulatory activity, MGSA-(54-72). Chi1 protein showed receptor-binding specificity and biological activity similar, but not identical to IL-8 and decidedly different from MGSA. The structure of Chi1 was determined in solution by two-dimensional NMR and molecular-dynamics calculations. The structure resembled the structures of MGSA and IL-8 closely, containing a triple-stranded beta-sheet in the IL-8 part and an amphipathic alpha-helix in the MGSA part. Chi1 formed dimers at millimolar concentrations via the first strand from the N-terminus, analogous to IL-8 and MGSA. In contrast to the latter molecules, however, the alpha-helix of Chi1 did not pack against the beta-sheet part, but was an independent structural element. This structural difference could be explained mainly by the modulation of hydrophobic interactions between the helix and the rest of the protein in Chi1 as compared to IL-8 and MGSA. It is concluded that tight helix packing is not required for receptor binding and biological activity of Chi1.

Amino Acid Sequence↗
PubMed1996

Cerebellomedullary compression in recessive craniometaphyseal dysplasia.

Craniometaphyseal dysplasia (CMD) is a very rare disorder of bone remodelling characterised by sclerosis of the skull base, vault and facial bones and metaphyseal splaying of tubular bones. The recessive form appears to be more severe than the dominant. Cranial nerve deficits have been reported in infancy and early childhood in a few patients, but the long-term history of recessive CMD is not well documented. We report cerebellomedullary compression in a girl with recessive CMD recognised at 14 years because of progressive truncal ataxia. MRI revealed backward angulation of the thickened clivus, narrowing of the foramen magnum and upward deviation of the cerebellum by a markedly thickened occipital squama, tonsillar herniation and obliteration of the infratentorial cerebrospinal fluid spaces. Posterior cranial fossa decompression resulted in marked improvement of the ataxia. Compression of posterior cranial fossa structures has to be considered in the natural history and management of CMD.

Brain Diseases↗
PubMed1995

Cytoplasmic domain of the ubiquitous Na+/H+ exchanger NHE1 can confer Ca2+ responsiveness to the apical isoform NHE3.

The Na+/H+ exchanger isoforms NHE1 and NHE3 are regulated differently by various stimuli. Calcium has been recognized as one of the major second messengers in such exchanger regulation. We previously proposed that Ca(2+)-induced activation of NHE1 occurs via displacement of its autoinhibitory domain from the H+ modifier site due to direct binding of Ca2+/calmodulin. To further validate this hypothesis, the functional role of the cytoplasmic domain was studied in both wild-type and chimeric exchangers, i.e. NHE1, NHE3, NHE1 with the cytoplasmic domain of NHE3 (N1N3), and NHE3 with the cytoplasmic domain of NHE1 (N3N1). After expression in exchanger-deficient fibroblasts (PS120), early response (< 80 s) to external stimuli was assessed as 5-(N-ethyl-N-isopropyl)amiloride-sensitive 22Na+ uptake. Among stimuli tested (ionomycin, alpha-thrombin, phorbol ester, hyperosmotic stress, and platelet-derived growth factor) that are all known to activate NHE1, only ionomycin and thrombin induced a significant intracellular Ca2+ mobilization and early activation of 22Na+ uptake, implying that Ca2+ is a main regulator of NHE1 in the early phase of the agonist response. However, all the stimuli did not activate NHE3 or N1N3. In contrast, a significant stimulation of 22Na+ uptake in response to ionomycin and thrombin was observed in N3N1, accompanied by an alkaline shift of pHi sensitivity (approximately 0.2 pH units). Deletion of the cytoplasmic calmodulin-binding domain within N3N1 resulted in a constitutive alkaline shift of pHi sensitivity and abolished the activation by ionomycin and thrombin. Together, these data reinforce our concept of Ca(2+)-induced activation of NHE1. Furthermore, they provide evidence for a functional interaction of the autoinhibitory domain of NHE1 with the H(+)-modifier site of a different isoform, NHE3.

Amiloride↗
PubMed1995

CD30 ligand signal transduction involves activation of a tyrosine kinase and of mitogen-activated protein kinase in a Hodgkin's lymphoma cell line.

CD30 is a transmembrane receptor of the nerve growth factor/tumor necrosis factor receptor superfamily. Its expression associated with Hodgkin's lymphoma and a subset of non-Hodgkin's lymphoma. Recently, its ligand (CD30L) has been cloned. CD30L enhances the proliferation of peripheral T cells and the Hodgkin's cell line HDLM-2 but seems to exert antiproliferative effects on large cell anaplastic lymphoma cell lines. Since tyrosine kinases are critical regulators of cell growth, we investigated whether CD30L induced changes in cellular tyrosine phosphorylation in CD30-positive lymphoma cell lines. Stimulation with CD30L or with an agonistic mAb against CD30, M44, induced a rapid, transient, and concentration-dependent tyrosine phosphorylation of a cytosolic protein of M(r) 42,000 (p42) in the Hodgkin's lymphomas cell line HDLM-2 but not in other CD30-positive lymphomas. In HDLM-2 cells, the phrobol ester phorbol 12-myristate 13-acetate also stimulated tyrosine phosphorylation of p42, and this effect was enhanced by M44. In marked contrast, agents stimulating the protein kinase A pathway, like forskolin or dibutyryl cAMP, did not affect tyrosine phosphorylation of P42. By immunoprecipitation with mAbs against mitogen-activated protein kinase (MAPK; p42ERKII), a M(r) 42,000 protein was identified which comigrated with p42 on SDS gels and which was phosphorylated on tyrosine residues in response to stimulation of CD30. Immune complex kinase assays showed that M44 mAb induced the activation of MAPK (p42ERKII) and the phosphorylation of a MAPK substrate, myelin basic protein. Taken together, the results suggest that CD30L induces the tyrosine phosphorylation and activation of the MAPK p42ERKII isoform in HDLM-2 cells. These findings may have implications for the understanding of the pathogenesis of Hodgkin's disease.

CD30 Ligand↗
PubMed1995

Baculovirus-driven expression and purification of glycine receptor alpha 1 homo-oligomers.

The glycine receptor is a ligand-gated anion channel protein of postsynaptic membranes. We expressed a homo-oligomeric receptor composed of human alpha 1 subunits in Spodoptera frugiperda cells by infection with a recombinant Autographa californica nuclear polyhedrosis virus. A substantial fraction of the recombinant receptor was incorporated as a functional channel protein into the cell's plasma membrane at expression levels 4- to 30-fold higher than in other eukaryotic heterologous expression systems or native rat spinal cord membranes, respectively. Upon detergent solubilization, the alpha 1 receptor was found to exist in a predominantly monodisperse state and could be affinity-purified to near homogeneity. This preparation is a potential starting point for future crystallisation studies.

Animals↗
PubMed1995

p53 mutation and MDM2 amplification are rare even in human papillomavirus-negative cervical carcinomas.

BACKGROUND: Mutation of the p53 tumor suppressor gene is the most commonly found genetic alteration in human cancer. The E6 gene product of human papillomavirus (HPV) 16 and 18 can inactivate the p53 protein by promoting its degradation. Because most HPV-positive cervical carcinoma cell lines contain wild-type p53 whereas HPV-negative cell lines have point mutations in the p53 gene, a major role in the development of HPV-negative cervical cancer has been attributed to p53. Recent studies, however, have observed no consistent presence of p53 mutation in HPV-negative primary cervical carcinomas. The MDM2 oncogene, which forms an autoregulatory loop with the wild-type p53 protein, has been found amplified in a high percentage of human sarcomas, thus abolishing the antiproliferative function of p53. METHODS: Forty-three primary cervical carcinomas and 10 autopsy-derived distant metastases from one patient were examined for p53 mutation and MDM2 amplification. These tumors had been selected from 238 cervical cancers that had been HPV-typed by Southern blot hybridization and polymerase chain reaction as a representative sample for their HPV status and their clinicopathologic characteristics. Seventeen of the cases had a remarkably good or poor clinical outcome. Human papillomavirus DNA sequences had been detected in 30 of these 43 primary tumors and 13 were negative for HPV by both methods. p53 mutation in the highly conserved exons 5-8 was studied by single-strand conformation polymorphism analysis and direct sequencing. MDM2 amplification was analyzed by Southern blot hybridization. RESULTS: Only two missense point mutations and one nucleotide sequence polymorphism were detected: a TAC-->TGC transition in codon 234 in exon 7, resulting in a Tyr-->Lys substitution, a CGT-->TGT transition in codon 273 in exon 8, resulting in an Arg-->Cys substitution and a polymorphism (CGA-->CGG) in codon 213 in exon 6. Both tumors revealing the point mutations were HPV-negative carcinomas. Amplification of the MDM2 gene was observed in 1 of the 53 specimens tested. CONCLUSIONS: In contrast to data derived from cultured cervical carcinoma cell lines and primary sarcomas, these results indicate that p53 mutation and amplification of the MDM2 oncogene are rare even in HPV-negative primary cervical carcinomas. However, to the authors; knowledge, this is the first observation of MDM2 amplification in humans outside sarcomas and neuroepithelial tumors.

Adult↗
PubMed1995

Kinetic study in vitro of Escherichia coli promoter closure during transcription initiation.

The rate of closure of two Escherichia coli promoters borne by plasmid pBR322, following transcription initiation from the open complex, was probed in vitro by the protection of unpaired thymines in the open complex against oxidation by KMnO4. Run-off transcription kinetics were also studied under identical conditions. Closure of the open promoter appears to be by far the rate-limiting step of transcription initiation and elongation for the linearized beta-lactamase gene, and is strongly dependent on template topology for the RNAI gene. It is suggested that the corresponding signals are deposited 30 bases at least downstream of transcription initiation and that promoter closure, and its clearance by elongating RNA polymerase, may occur almost simultaneously.

Base Sequence↗
PubMed1995

A clinical and immunological study on 92 workers occupationally exposed to anhydrides.

This study aimed at investigating sensitizing and hazardous effects of a new acid anhydride, pyromellitic dianhydride (PMDA), in addition to those of phthalic anhydride, maleic anhydride and trimellitic anhydride, in a group of 92 exposed workers in two German chemical plants. Of the 92 workers, 56 reported work-related complaints with a predominance of phlegm and dyspnoea in those exposed to anhydride dust for less than 1 year. Haemorrhagic rhinitis occurred only after a prolonged exposure of more than 15 years. Specific IgE antibodies to anhydride-HSA conjugates could be detected in 15 exposed subjects, 12 of whom had work-related symptoms. The IgE-positive group had significantly more impaired lung function parameters than the IgE-negative group. The proportion of IgE-positive subjects was highest in the groups with dyspnoea (5/18), cough (6/24) and rhinitis (11/44) whereas only 1 of 11 workers with haemorrhagic rhinitis had such antibodies. A follow-up study of 23 affected workers was performed after 10 months to assess clinical symptoms, lung function and IgE antibody levels. This follow-up study showed the absence of obstructive ventilation patterns in three out of six subjects in addition to cessation of symptoms in most initially affected workers who were no longer exposed. On the other hand, 14 workers under continuous exposure had comparable pathological findings on re-examination. Our results confirm that anhydrides including the lesser known PMDA, behave as respiratory irritants and as immediate-type sensitizers. They predominantly induced reversible symptoms in workers whose exposure stopped after a working period of about 0.7 years. Abnormal lung function parameters normalized in nearly 50% of these subjects.

Adult↗
PubMed1995

[Rural communes and small towns in the urban hierarchy].

"A determining factor in the demographic and employment dynamics of rural communes and certain small towns [in France] is how far they are from the nearest large town. Demographic dynamics and employment trends are somewhat adverse for those living far from urban influences. The main reasons for this would appear to be the slump in agriculture. This said, demographic and employment trends are much improved nearer the large towns, especially since the towns exerting the influence have more inhabitants." (SUMMARY IN ENG AND GER AND SPA)

Demography↗
PubMed1995

[Thoracic actinomycosis].

Thoracic actinomycosis is a rare disease without characteristic clinical signs. Approximately 90% of patients suffering from thoracic actinomycosis have undergone diagnostic and therapeutic procedures based on a wrong diagnostic hypothesis (malignancies 35-44%, other pulmonary disorders 33-35%). The opportunities for a timely and adequate diagnosis by the use of clinical examination, laboratory studies, microbiology studies, radiologic imaging or invasive measures are limited. In 85%, thoracic actinomycosis has not been identified prior to thoracotomy, open biopsy and histological examination. Based on a wrong diagnostic hypothesis, resective thoracic surgery according to the principles of oncologic surgery can hardly be avoided. We report on a 43-year-old male suffering from actinomycosis of the left hemithorax. Clinical signs, differential diagnosis, treatment and clinical course are described. The role of surgery in the treatment protocol of thoracic actinomycosis is discussed. In pulmonary and pleural disorders of unknown origin, differential diagnosis should include thoracic actinomycosis as early as possible. Due to the considerably high mortality rate of untreated disease, the outcome of thoracic actinomycosis can only be improved by a timely and combined employment of surgical and antibiotic therapy.

Actinomycosis↗
PubMed1994

Angelman syndrome due to paternal uniparental disomy of chromosome 15: a milder phenotype?

The Angelman syndrome (AS) is a neurological disorder characterized by severe mental retardation, absent speech, seizures, gait disturbances, and a typical age-dependent facial phenotype. Most cases are due to an interstitial deletion on the maternally inherited chromosome 15, in the critical region q11-q13. Rare cases also result from paternal uniparental disomy of chromosome 15. In a group of 14 patients with sporadic AS diagnosed in Switzerland, we found 2 unrelated females with paternal isodisomy for the entire chromosome 15. Their phenotypes were milder than usually seen in this syndrome: one girl did not show the typical AS facial changes; both patients had late-onset mild seizures; as they grew older, they had largely undisturbed gross motor functions, in particular no severe ataxia. Both girls were born to older fathers (45 and 43 years old, respectively). The apparent association of a relatively milder phenotype in AS with paternal uniparental disomy will have to be confirmed by detailed clinical descriptions of further patients.

Adult↗