Enzyme histochemistry of human brain tumors and their tissue cultures with special reference to the oxidoreductases in the glioblastoma multiforme

Summary Fresh tissue and tissue cultures of 80 glioblastoma multiforme and 12 monstrocellular sarcoma were histochemically investigated. The activity of the following enzymes was demonstrated in the biopsies and tissue cultures of every tumor: NADH-tetrazolium reductase, NADPH-tetrazolium reductase, lactic dehydrogenase, succinic dehydrogenase, glutamic acid dehydrogenase and cytochrome oxidase. No major differences in the relative activity pattern was shown when fresh tissue and tissue cultures were compared, nor did the enzymatic pattern change during the four week observation time.In both groups major quantitative differences in the enzymatic activity of the tumor cells in the same tissue area or tissue cultures were frequently a striking finding. Differences in the intracellular localization of the enzymatic activity were also observed. In slowly growing gliomas these histochemical variations are absent.     

Comparative Effects of Chronic Haloperidol and Sulpiride Treatment on Nigral and Striatal GABA Content

Nigral and striatal GABA contents were assayed in male rats treated chronically with haloperidol or sulpiride, two dopamine-receptor blocking agents that have different neuropharmacological spectra in regard to their biochemical, behavioural, and clinical properties. No great difference was observed between the chronic effects of haloperidol and sulpiride on nigral and striatal GABA content. However, low doses (30 μg/kg, intraperitoneally) of the dopamine-receptor agonist apomorphine, injected 12 h after the discontinuation of chronic haloperidol or chronic sulpiride treatment, induced opposite changes in nigral GABA levels suggesting the existence of a different “status” of the dopamine receptors during the 12 h-period following the withdrawal of haloperidol or sulpiride.     

Flavonol glycosides from Pteridium aquilinum

Two new flavonol glycosides from aerial parts of Pteridium aquilinum were identified as quercetin 3-O-β-laminaribioside and isorhamnetin 3-o-β-laminaribioside by chemical and spectroscopic methods.     

A novel mechanism for the origin of supernumerary marker chromosomes

A ring chromosome 3 and a 47^th chromosome formed by the portions of 3p and 3q distal to the r(3) breakpoints were found in a girl with mental retardation and minor facial anomalies. The supernumerary chromosome 3, rea(3), had a primary constriction inside its 3p portion (3p23) and was consistently stable both in lymphocytes and fibroblasts. In situ hybridization with alphoid probes revealed that the r(3) maintained its wild-type centromere, whereas the rea(3) showed no alphoid-related signals. This case and a similar one recently reported demonstrate that acentric fragments can acquire a new centromere and become stable, and that supernumerary marker chromosomes can also originate by the junction of the acentric portions distal to the centric region forming a ring. The possibility of such a chromosome segregating will depend on its ability to (re)activate a new centromere.     

The Addition of Dexfenfluramine to Fluoxetine in the Treatment of Obesity: A Randomized Clinical Trial

Current evidence demonstrates that pharmacologic agents, alone or in combination produce short-term weight-loss and may remain effective for extended periods of time in obese patients. We have evaluated the weight loss of a selective inhibitor of serotonin uptake, fluoxetine, alone as compared with combined therapeutic trial with another serotoninergic drug, dexfenfluramine. Thirty-three patients were randomly assigned in a double-blind randomized clinical trial divided to two groups: Group I [Fluoxetine 40 mg and placebo (n=13)] and Group II [Fluoxetine 40 mg plus dexfenfluramine 15 mg at night (n=20)]. Both groups had a significant weight loss at the end of 8 months (Group I, mean ± SEM 6.2 ± 2.8 kg and Group II 13.4 ± 6.3 kg, p < 0.05). Group II patients had a significantly greater weight loss as compared with Group I both in terms of mean weight loss in kg and BMI in kg/m². However significance between Group I and II related to BMI mean values and weight mean values were only achieved after, respectively, 4 and 6 months of treatment. At laboratory level there was an elevation of HDL-cholesterol and lowering of serum lipids values (cholesterol and triglycerides) in both groups. Side effects were relatively minor and no altered clinical vital signs or abnormal laboratory values were observed. We concluded that the combination of fluoxetine (daytime) and dexfenfluramine (at night) may be more effective than fluoxetine alone in weight reduction although the small size of this study does not permit broad generalization.     

Mass spectrometric analysis of the HMGY protein from Lewis lung carcinoma. Identification of phosphorylation sites.

The primary structure of the Lewis lung carcinoma protein HMGY belonging to the nuclear group of proteins HMGI (high mobility group I) was determined using electrospray and fast atom bombardment mass spectrometry. It was demonstrated that the sequence of the tumor protein corresponds to the amino acid sequence derived from the cDNA from cultured cells and that the N-terminal serine residue is N-acetylated. Moreover, the two high performance liquid chromatography-purified forms Y1 and Y2 of the protein HMGY were shown to differ at the level of serine phosphorylation, since they contain three phosphate and two phosphate groups, respectively, in the C-terminal region. No other modification was detected in the remaining part of the molecule.     

A novel fibronectin receptor with an unexpected subunit composition (alpha v beta 1)

The integrins are a family of heterodimeric cell surface receptors for extracellular matrix molecules. An analysis of integrin subunits expressed by a number of cell lines identified a novel heterodimer. The alpha subunit of this integrin was immunologically and electrophoretically indistinguishable from the vitronectin receptor alpha subunit (alpha v) and the beta subunit was indistinguishable from beta 1. Affinity chromatography experiments and cell adhesion assays indicated that this receptor complex is a new fibronectin receptor. Its unexpected subunit composition demonstrates the importance of the beta subunit in determining the ligand specificity of integrins and suggests that the current integrin classification scheme needs revision.     

Nerve growth factor induces increased expression of a laminin-binding integrin in rat pheochromocytoma PC12 cells

Rat pheochromocytoma PC12 cells exposed to nerve growth factor differentiate as sympathetic neurons and extend neurites on laminin and to a much lesser extent on fibronectin. Analysis of laminin fragments indicated that neurite outgrowth occurs mainly on fragment P1, corresponding to the center of the cross, and only poorly on fragment E8, a long arm structure that is active with other neuronal cells. Integrin antibodies prevented adhesion and neurite sprouting of these cells on laminin, fragment P1, and fibronectin. By affinity chromatography we isolated an integrin-type receptor for laminin consisting of two subunits with molecular massess of 180 and 135 kDa. The latter is recognized by an antiserum to integrin beta 1 subunit. The bound laminin receptor could be displaced by EDTA, but not by Arg-Gly-Asp or Tyr-Ile-Gly-Ser-Arg peptides. Affinity chromatography on laminin fragments showed that the 180/135 kDa receptor binds to P1. The expression of the 180-kDa alpha subunit of the laminin receptor at the cell surface was increased 10-fold after NGF treatment. The effect of NGF is specific since the amount of a 150-kDa fibronectin-binding integrin alpha subunit remained unchanged. Moreover, the increased expression of the 180/135 kDa receptor at the cell surface corresponded to a selective increase in cell adhesion to laminin and to fragment P1. The 180/135-kDa complex is thus an integrin-type receptor for laminin whose expression and binding specificity correlates with the capacity of NGF-induced PC12 cells to extend neurites on laminin.     

Cocultivation of Fanconi anemia cells and of mouse lymphoma mutants leads to interspecies complementation of chromosomal hypersensitivity to DNA cross-linking agents

Summary We have studied the effects of cocultivation on the frequency of mitomycin C (MMC)-induced chromosomal aberrations. This was carried out by cocultivating Fanconi anemia (FA) cells from the genetic complementation groups A and B with both normal mouse lymphoma L5178Y cells and the derived FA-like mutant cells, MCN-151 and MCE-50, assigned to complementation groups I and II, respectively. The results show a partial complementation of the defect (i.e. a reduction in the frequency of chromosomal aberration) in FA group A cells cocultured with normal or group II mouse cells, and a partial correction of mouse group I cells cocultived with normal or FA group B human cells. No reciprocal effects were observed between FA group A cells and mouse group I mutant cells; the frequencies of MMC-induced chromosomal aberrations in these cells remained unchanged by cocultivation. Moreover, no complementation was observed for both FA group B cells and mouse group II cells, after cocultivation with normal cells of either mouse or human origin. This implies that a diffusible factor released by normal human and mouse cells, and by FA group B and mouse group II mutant cells, can correct at least in part the chromosomal defect of FA group A and mouse group I mutant cells. With normal human or mouse cells, the frequency of chromosomal breakage after cocultivation remains the same as that observed in non-cocultived cells. This suggests that no detectable clastogenic factor is released by human FA or FA-like mouse cells.