Isolable N-heterocyclic carbene adducts of the elusive diiodophosphine.

Reactions of PH-substituted phosphinidene-imidazolylidenes with I2 afford isolable NHC-adducts of the transient diiodophosphine PHI2. The products, which show a surprising structural diversity, are according to DFT studies best formulated as charge-transfer complexes of onio-substituted cationic phosphines with I- and are capable of reaction under formal transfer of an NHC-P+ unit.

Cytogenetic, ras, and p53: studies in cases of canine neoplasms (hemangiopericytoma, mastocytoma, histiocytoma, chloroma).

Four case reports of mesenchymal neoplasms showing chromosomal abnormalities are presented. In a case of hemangiopericytoma trisomy 2 and centric fusion 19;21 were present. In a mastocytoma a deleted chromosome 35 was seen. A homogeneously staining region (HSR) on chromosome 1 was detected in a histiocytoma. Trisomy 5 and monosomy 31 were observed in a case of granulocytic sarcoma (chloroma). The lack of mutations in exons 1 and 2 of oncogenes N-ras, K-ras, and H-ras and exons 5, 6, 7, and 8 of tumor suppressor gene p53 in these four patients and in a larger series of investigated dogs (25 hemangiopericytomas, 12 mastocytomas, and 8 histiocytomas) is highlighted.

Endothelial cells differentially express functional CXC-chemokine receptor-4 (CXCR-4/fusin) under the control of autocrine activity and exogenous cytokines.

Analysis of endothelial cell (EC) chemokine receptor expression by RT-PCR revealed that EC essentially do not express CC-chemokine receptors whereas they express all known CXC-chemokine receptors. Endotheliotropic functions of ligands for CXCR-1, CXCR-2, and CXCR-3 have previously been described. We have consequently performed a detailed analysis of endothelial CXCR-4 expression. CXCR-4 is constitutively expressed by quiescent, resting EC. Cytokine stimulation revealed that bFGF upregulates endothelial CXCR-4 expression, whereas TNF alpha downregulates endothelial CXCR-4 expression. Expression of CXCR-4 mRNA as well as protein is also upregulated in autocrine activated, migrating bovine aortic endothelial cells (BAEC). Furthermore, migrating BAEC preferentially present CXCR-4 on the cell surface as evidenced by cytochemistry and FACS analysis. Lastly, the monospecific CXCR-4 ligand SDF-1 was found to act as a potent inducer of EC chemotaxis. In summary, the data indicate that the CXCR-4/SDF-1 receptor ligand interaction may be an important regulator of activated endothelial cell functions as they occur during vascular remodeling and angiogenesis.

Cytogenetic alterations in eight mammary tumors and tumor-suppressor gene p53 mutation in one mammary tumor from dogs.

OBJECTIVE: To identify mutations in canine mammary tumors. ANIMALS: 10 tumor-bearing dogs. PROCEDURE: Culture of neoplastic cells originating from mammary tumors was performed, and trypsin-G banding was used for cytogenetic investigations. The same tumors were subjected to molecular genetic screening by use of DNA extraction, polymerase chain reaction, DNA elution, and DNA sequencing for ras oncogenes and the p53 tumor suppressor gene. RESULTS: A broad spectrum of chromosome aberrations was observed, including trisomies, reciprocal translocations, and structural and numerical X-chromosome alterations and deletions. Molecular genetic analysis revealed a tumor suppressor p53 gene mutation in codon 249 of exon 7 in one instance. Interestingly, analyzed mammary tumors were free of mutations in N-ras, K-ras and H-ras, exons 1 and 2. CONCLUSIONS: Chromosome alterations are wide-spread in canine mammary tumors, but no ras family mutations were detected in tumors from these 10 dogs. CLINICAL RELEVANCE: Knowledge about chromosome, oncogene, and tumor suppressor gene damage could be helpful for diagnosis and prognosis of neoplastic diseases in dogs.

Crystallization and preliminary X-ray crystallographic analysis of squalene-hopene cyclase from Alicyclobacillus acidocaldarius.

The membrane-associated protein squalene-hopene cyclase from Alicyclobacillus acidocaldarius was overexposed in Escherichia coli and purified by ion exchange and gel permeation chromatography. Crystals of three interrelated forms were grown by vapor diffusion under identical conditions. The crystals diffract to about 2.3 A resolution, but they are unstable in the X-ray beam. An interpretable heavy-atom derivative was obtained.

Site-directed mutagenesis of putative active-site residues in squalene-hopene cyclase.

Squalene-hopene cyclase (SHC) catalyzes the complex polycylization of squalene to hopene, similar to the cyclization of oxidosqualene to sterols. Sequence analysis of SHC revealed a highly conserved aspartate-rich motif (DDTA), comparable to the DCTA motif of oxidosqualene cyclases, which is supposed to be part of the active site. In order to determine the importance of the motif in squalene cyclization, the conserved residues Asp376 and Asp377 in the DDTA motif of SHC from Alicyclobacillus acidocaldarius were individually replaced by glutamate, glutamine, glycine, and arginine. With the exception of the [Glu376]SHC mutant, all other substitutions resulted in almost or complete loss of enzyme activity. Compared to that of the wild-type enzyme, the specific activity of the [Glu376]SHC mutant enzyme was reduced to 10%, accompanied by a significant decrease in the apparent Vmax, whereas the apparent K(m) remained unchanged, CD measurements indicated that mutations did not affect the secondary structure. It is proposed that Asp376 and Asp377 are crucial for catalysis and may act as point charges to stabilize intermediate cations. Moreover, for squalene-hopene cyclase, a high content of alpha-helical conformation could be found, providing the first structural information for a triterpene cyclase.

Genetic and biochemical analyses of the biosynthesis of the yellow carotenoid 4,4'-diaponeurosporene of Staphylococcus aureus.

The major pigment produced by Staphylococcus aureus Newman is the deep-yellow carotenoid 4,4'-diaponeurosporene; after prolonged cultivation, this pigment is in part converted to the orange end product staphyloxanthin. From this strain a 3.5-kb DNA fragment was identified which after being cloned into Escherichia coli and Staphylococcus carnosus conferred the ability to produce 4,4'-diaponeurosporene. DNA sequencing of this fragment revealed two open reading frames (ORFs) which are very likely cotranscribed. ORF1 encodes a 254-amino-acid hydrophobic protein, CrtM (M(r), 30,121). The deduced sequence of CrtM exhibits in three domains similarities to the sequences of Saccharomyces cerevisiae and human squalene synthases and phytoene synthases of various bacteria. ORF2 encodes a 448-amino-acid hydrophobic protein, CrtN, with an M(r) of 50,853 whose deduced sequence is similar to those of phytoene desaturases of other bacteria. At the N terminus of CrtN a classical FAD-, NAD(P)-binding domain is found. Spectrophotometry and gas chromatography-mass spectrometry analyses of the carotenoid production of E. coli and S. carnosus clones containing either ORF1 or both ORFs together suggest that ORF1 and ORF2 represent the dehydrosqualene synthase gene (crtM) and the dehydrosqualene desaturase gene (crtN), respectively. The results furthermore suggest that the biosynthesis of 4,4'-diaponeurosporene starts with the condensation of two molecules of farnesyl diphosphate by dehydrosqualene synthase (CrtM); it is shown that the reaction product of this enzyme is dehydrosqualene and not squalene. Dehydrosqualene (4,4'-diapophytoene) is successively dehydrogenated by a desaturase (CrtN) to form the yellow main intermediate 4,4'-diaponeurosporene.

[Renal leiomyoma. Apropos of a case]. / Léiomyome rénal. A propos d'un cas.

Leiomyoma of the kidney is a rare tumor, for which little investigational imaging data is available, and which is poorly characterized by histological methods. We are here concerned with one case that benefitted from an extensive radiological workup, and we provide a comparison with other cases mentioned in the literature.

[Fine needle cytopuncture of the pancreas. Apropos of 45 cases]. / Cytoponction pancréatique à l'aiguille fine. A propos de 45 observations.

In this report, we examined the sensitivity and specificity of pancreatic fine needle aspiration cytology in the diagnosis of pancreatic cancer. Aspiration cytodiagnosis was performed in 45 patients (36 cancers and 9 benign pancreatic lesions) using a 22 Gauge fine needle either percutaneously in 25 patients with real-time ultrasonic guidance or during surgery in 20 patients. Cytologic examination included a precise description and the classification in one of the 4 Papanicolaou classes, the fourth only being considered as positive in terms of cancer. No complication occurred with either technic. Overall sensitivity was 75 p. 100, 74 p. 100 percutaneously and 77 p. 100 intraoperatively, but specificity was 78 p. 100 due to two false-positive results recorded among the 9 benign lesions. Retrospective analysis of cytologic examinations of the 29 class IV lesions led us to differentiate cases with "sure malignancy" (20 cases) from those with "strong suspicion of malignancy" (9 cases including the 2 false-positives). Only class IV lesions with "sure malignancy" call for aggressive treatment, whereas a "strong suspicion of malignancy", which may result from carcinoma or severe cellular abnormalities occasionally found in inflammatory pancreatic lesions, should lead to a second pancreatic aspiration.

Migrant children in the German kindergarten: data, problems, and pedagogical models.

PIP: The integration of migrant children into German society is a controversial pedagogical task for educational institutions. An important part of this task is assigned to the kindergarten, since the early learning of social values and norms increases the chance of integration. The increasing number of migrant children in kindergartens has confronted teachers with new problems and changed tasks. In the 1980s, almost all kindergartens have migrant children enrolled in them; in some urban areas, there are kindergartens with 50% or more migrant children students. Some migrant children confront the use, or the continous use, of the German language for the 1st time in kindergarten. A secondary danger is abandoning a child with incomplete knowledge and inadequate German. These children will encounter new language problems in school. Although very little information is available on migrant parents' opinions of kindergartens, the limited data available indicate that parents generally respond favorably, although they fear alienation from their children. The migrant parents expect the kindergartens to teach their children German. The German kindergarten will not and cannot prepare children for life in their home country, even if it is kindly disposed towards a multitude of cultures. The kindergarten is only able to prepare children for life in Germany. Migrant children have special problems with bilingualism and cultural distance. Migrant children do not "cause" problems. Rather they offer an occasion to reflect on the work of the kindergarten and to include new and different experiences.^ieng

[The investigation of pancreatic pathology by "grey range" echotomography. Study of 80 cases (author's transl)]. / Exploration pancréatique par l'échotomographie "gamma des gris". Etude de 80 dossiers.

Over an 18-month period, the authors studied 305 cases of patients with or suspected of having pancreatic disease. Although atraumatic and free of danger, it must be borne in mind that echotomography is hampered by the air and water barrier of the hollow organs of the intestines since 20% of subjects cannot be explored. Well defined full or empty pancreatic tumours and acute inflammatory syndromes have well defined echographic appearances. In cases of chronic pancreatitis or poorly defined tumours the diagnosis is more difficult and ultrasound examination often only provides an additional element in a clinical argument. The great reliability of this examination should lead to its use at the beginning of investigations, with the possibility of the result orienting the clinician towards less harmless examinations.