This study analyzed the expression of stress-response (heat-shock) protein 60 (srp 60) in a series of 158 human brain tumours. Immunohistochemical procedures were employed; cells of the human cervical cancer line HeLa S3 exposed to hyperosmolar stress served as positive controls. Deposits of reaction products were found in the cytoplasm. Approximately half of the glioblastomas multiforme (17/31), breast carcinoma metastases (6/10), and lung carcinoma metastases (5/11) as well as about one-third of the astrocytomas (5/13) and meningiomas (8/23) had tumour cells that expressed srp 60. A positive reaction for srp 60 was also seen in some medulloblastomas (2/16), primitive neuroectodermal tumours (PNETs) (2/11), schwannomas (2/21), and pituitary adenomas (2/7), but no positive reactions were observed with oligodendrogliomas and ependymomas. Compared with srp 60-negative tumours, srp 60-positive tumours coexpressed one or more stress-related proteins, among which srp 90, srp 72, srp 27, alphaB-crystallin and ubiquitin occurred with higher frequencies; a high correlation between srp 60 and the other five srps (0.88 - 0.97, p<0.01, Pearson correlation coefficient) was observed in srp 60-positive tumours. In contrast, the correlation coefficient in srp 60-negative tumours was not significant (-0.26 - 0.71). There was a tendency for the proliferating cell nuclear antigen (PCNA)-labeling index to be higher in glioblastomas, astrocytomas, medulloblastomas, PNETs, and breast and lung carcinoma metastases that expressed srp 60 than in those that did not. No significant immunohistochemical reactions of srp 60, PCNA and p53 protein were seen with sections of normal brain tissues. We conclude that primary and metastatic tumours of the brain produce srp 60 and that srp 60 in certain brain tumour cells may coexpress the other five srps. In addition, srp 60 expression might depend, in part, on proliferating potential.
Monkey cells persistently infected by measles virus (MV) Biken strain (Biken-CV-1 cells) showed no cytopathic effects and lacked surface expression of a homolog of human cell receptor, membrane cofactor protein CD46. Transfection of a human CD46 gene into these cells induced extensive cell fusion, indicating that down regulation of the endogenous CD46 homolog was essential for the maintenance of a noncytopathic mode of infection. Surface expression of the exogenously introduced human CD46 was also drastically down regulated in the persistently infected cells compared with uninfected cells. The down regulation was specific for CD46 and did not affect surface expression of exogenously introduced CD4. Exogenous human CD46 was synthesized efficiently in the persistently infected cells, but it did not accumulate on the cell surface. Fusion of Biken-CV-1 cells required the extracellular hemagglutinin (H-protein)-binding domain but not the cytoplasmic domain. Replacing the transmembrane and cytoplasmic domains of CD46 with a glycosylphosphatidylinositol anchor did not prevent cell fusion but completely alleviated down regulation of the glycosylphosphatidylinositol-anchored CD46 in Biken-CV-1 cells. Deletion analyses revealed that the membrane-distal sequences of the CD46 cytoplasmic domain were not only unnecessary but also inhibitory for CD46 down regulation. By contrast, the six amino acid residues proximal to the membrane contained a sequence required for CD46 down regulation in the persistently infected cells. These results indicate that CD46 is down regulated in the persistently infected cells by a mechanism that recognizes a membrane-proximal sequence in the CD46 cytoplasmic domain.
Abstract Crystals of sodium hydrogen l-tartrate monohydrate (NaHC4H4O6·H2O) were grown from the aqueous solution, while potassium hydrogen l-tartrate (KHC4H4O6) crystallized as anhydrate. Their crystal structures were determined by X-ray diffraction method. The hydrogen bonds between the carboxyl and carboxylate groups in these crystals are rather long; O···O 2.533(3) and 2.531(1) Å for the sodium and potassium compounds, respectively. The sodium and potassium ions are coordinated by eight O atoms at the corners of distorted square antiprism, Na+···O 2.404(2)—2.826(3) Å and K+···O 2.718(1)—3.059(1) Å. The crystal and molecular structures have been compared with those of the corresponding rubidium, caesium, and ammonium salts, and discussed with the aid of semiempirical and ab initio MO methods.
