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Biomedical subjects

J Seibel

Publications and source records attributed to J Seibel.

8 recordsLinked to original sources
PubMed2005

Tissue-specific modulation of cyclooxygenase-2 (Cox-2) expression in the uterus and the v. cava by estrogens and phytoestrogens.

Cyclooxygenase 2 (Cox-2), an enzyme involved in prostaglandin production, is a key player in the development of pathologic changes, such as colorectal cancer, arteriosclerosis and thrombosis. In this study, we investigated the effects of estrogens, selective estrogen receptor modulators (SERMs), pure antiestrogens and phytoestrogens on the tissue-specific expression of Cox-2 in the uterus and the v. cava of ovariectomized female rats. Cox-2 expression could be detected in the uterine epithelium and in the endothelium of the v. cava. Cox-2 expression was time-dependently stimulated after administration of 17beta estradiol (E2) in the uterus. In the v. cava, E2 treatment resulted in a stimulated expression of the progesterone receptor (PR), a gene known to be regulated by E2, whereas Cox-2 was simultaneously down-regulated. Administration of the pure antiestrogen faslodex (Fas) had no effect on Cox-2 expression. In contrast, administration of tamoxifen (Tam) resulted in a decrease of Cox-2 expression in the v. cava but does not stimulate Cox-2 expression in the uterus. Interestingly, the same expression pattern of Cox-2 could be detected after dose-dependent administration of genistein (Gen). Here, down-regulation of Cox-2 could already be detected after administration of merely 0.5 mg/(kgBW) Gen, a dose where no effects on uterine weight were observed. In summary, our results demonstrate a reverse tissue-specific regulation of Cox-2 expression by estrogens in the v. cava and uterus indicating the existence of complex molecular mechanisms which have to be characterized in future studies. Remarkably, Tam and the phytoestrogen Gen, both share the ability to decrease the expression of Cox-2 in the v. cava without effecting its uterine expression. These observations may be of great importance with respect to potential beneficial or adverse effects of estrogens, SERMs and phytoestrogens on the cardiovascular tissue.

Animals↗
PubMed2005

Investigations of the transfructosylation reaction by fructosyltransferase from B. subtilis NCIMB 11871 for the synthesis of the sucrose analogue galactosyl-fructoside.

The exo-fructosyltransferase produced from B. subtilis NCIMB 11871 strain transfers the fructose moiety from donor alpha12 linked saccharides such as sucrose, raffinose and stachyose to the acceptor d-galactose, leading to the sucrose analogue, galactosyl-fructoside. Here, we report detailed kinetic studies. The enzyme showed a remarkably high optimal temperature at 50 degrees C and was effectively immobilised on Eupergit C 250 L and Trisopor-Amino. This is also the first report about the equilibrium of the transfructosylation reaction, its activation energy determination, the structure of the product and its preparative scale isolation.

Bacillus subtilis↗
PubMed1998

Caffeine-derived N-nitroso compounds. V. Carcinogenicity of mononitrosocaffeidine and dinitrosocaffeidine in bd-ix rats.

Mononitrosocaffeidine (MNC) and dinitrosocaffeidine (DNC) are new N-nitroso compounds obtained from in vitro nitrosation of caffeidine, a hydrolysis product of caffeine present in a typically made and widely consumed tea from Kashmir (India), a high incidence area of esophageal and stomach cancer. The chemical synthesis, in vitro metabolic studies and mutagenicity of the compounds has been previously reported. DNC, a nitrosamide is highly mutagenic both with and without metabolic activation whereas MNC, like several other aromatic asymmetric nitrosamines, does not exhibit genotoxic or mutagenic properties. We now report the results of the first carcinogenicity experiments on chronic oral administration of these compounds in BD-IX rats. The acute LD50 of MNC and DNC were about 1300 and 230 mg/kg b.w., respectively. Lung oedema and gastrointestinal haemorrhages were the first symptoms of intoxication observed after 2 days for both the compounds. All three dose groups of MNC treated rats showed localization of tumours in nasal cavity (93.9-100% of all malignant tumours). The tumours were histologically diagnosed as neuroepitheliomas of the olfactory epithelium (neuroblastoma of the bulbus olfactorii) and squamous cell carcinoma of the nasal cavity in the ratio of 3:1. No tumours of the nasal cavity were observed in the untreated controls. DNC, in contrast, induced squamous cell carcinoma of forestomach in 100% animals at low and high doses, of which nearly half the tumours metastasized predominantly into the peritoneum. No forestomach tumours were seen in the untreated controls. The data presented here clearly show the potential for induction of malignant tumours and distinct organ-specificity by MNC and DNC in rats, and support the postulate that a chronic exposure to these compounds may provide a carcinogenic risk for high incidence of gastrointestinal cancers in Kashmir.

Administration, Oral↗
PubMed1982

Endocarditis caused by Actinobacillus actinomycetemcomitans.

Actinobacillus actinomycetemcomitans, a small, gram-negative bacillus with fastidious growth requirements, is a rare cause of endocarditis. The clinical course of this disease is characterized by long duration of symptoms before diagnosis (average of three months), prolonged incubation before growth (average of six days), and a high embolic rate. The optimal antimicrobial regimen cannot be determined from available data, but the combination of ampicillin and an aminoglycoside may offer the best chance for cure. Two cases are presented, one successfully treated. Previously reported cases are reviewed.

Actinobacillus Infections↗
PubMed1981

Vocal cord paralysis and psychopathology. Data and clinical issues.

The nature and cause of psychiatric symptoms associated with the posthyroidectomy bilateral abductor vocal cord paralysis (BAVCP) syndrome are analyzed. The postthyroidectomy BAVCP syndrome is characterized by normal voice, airway obstruction, hypothyroidism, hypoparathyroidism, and psychiatric manifestations. Forty-five (35.2%) of 128 patients with postthyroidectomy BAVCP syndrome had psychiatric manifestations of some kind. The following four categories of psychiatric problems were found: (1) preexisting psychiatric symptoms exacerbated by the postthyroidectomy BAVCP syndrome, (2) psychiatric symptoms initiated by the syndrome, (3) psychiatric symptoms that were etiologically distinct from the syndrome, and (4) misdiagnosis. The variety of psychiatric symptoms, as well as the difficulty in determining the cause of the symptoms, makes it essential that surgeons, internists, and psychiatrists cooperate in the treatment of patients with the postthyroidectomy.

Humans↗
PubMed1980

Psychiatric manifestations of the post-thyroidectomy bilateral abductor vocal cord paralysis syndrome. Cases and theoretical issues.

Post-thyroidectomy bilateral abductor vocal cord paralysis (BAVCP) is a life-threatening syndrome characterized by serious psychiatric manifestations as well as by voice, airway, hypothyroid, and hypoparathyroid symptoms. Of the 128 patients with post-thyroidectomy BAVCP syndrome, 45 (35.2 per cent) had psychiatric complications: 21 of the 128 patients (16.4 per cent) had pre-existing psychiatric symptoms exacerbated by the post-thyroidectomy BAVCP syndrome, 16 (12.5 per cent) had psychiatric symptoms initiated by the syndrome, six (4.7 per cent) had psychiatric symptoms etiologically distinct from the syndrome, and two (1.6 per cent) were misdiagnosed. The role of psychiatric treatment is described. Theoretical aspects of laryngeal dysfunctions associated with psychiatric disorders and psychotropic medications are discussed.

Adult↗