The Formation of Otoliths in the Frog Rana esculenta. Scanning Electron Microscopic and X-Ray Diffraction Studies

Two crystal forms of calcium carbonate were observed: calcite (utricle) and aragonite (saccule, lagena, endolymphatic sac). The first step in otolith formation is the appearance of organic structures in the macula. The subsequent step is characterized by fast growing primitive crystals with a prismatic habitus that successively transform into adult or mature crystals. With the metamorphosis, the aragonite crystals of the endolymphatic organ show clear signs of erosion that can be related to a process of CaCO₃ mobilization from such deposits.     

Effect of carbon dioxide on differentiation and on the level of a soluble b-type cytochrome in Phycomyces blakesleeanus

A soluble b-type cytochrome has been detected and partly characterized in mycelial extracts of Phycomyces blakesleeanus. As it is already known, CO₂ delays sporangiophorogenesis, but it also lowers the level of this cytochrome. A possible causal relationship between sporangiophorogenesis and the b-type-cytochrome level may exist. There is some correlation between the extent of the delay of sporangiophorogenesis and of the decrease in cytochrome-b level in wild type and mutants that are either resistant or sensitive to CO₂.     

Blood amino acids in chronic HBsAg positive liver disease

Typical changes in blood aminoacid concentrations have been described in patients with severe liver disease. In this study we measured the serum amino acid levels, by Beckman Aminoacid Analyzer, in 11 healthy subjects and 24 HBsAg-positive patients with biopsy-proven liver disease (4 CPH, 10 CAH, 10 cirrhosis). A significant decrease in total aminoacids was observed in CAH and cirrhosis groups (-24% and -22% respectively). The three branched chain aminoacids (BCAA = val + leu + isoleu) were reduced by 24% (P less than 0.002) and 37% (P less than 0.001) in the CAH and cirrhosis groups respectively. Tyrosine was the only of the aromatic aminoacids (AAA) to increase in cirrhotics (+ 34%, P less than 0.02). The molar ratio BCAA/AAA was 3.6 in controls, 3.8 in CPH, 3.1 in CAH (P less than 0.025) and 1.9 in cirrhosis (P less than 0.001). A linear correlation was found between molar ratio BCAA/AAA and serum albumin in all patients (P less than 0.001). These results document the presence of specific quantitative changes in serum aminoacids of HBsAg positive patients, which appear related to severity of liver disease and comparable to the alterations described in non viral chronic liver disease.     

FAST (Flexible Analysis by Software Tool) and CHAMP (CHemico-physical AMinoacidic Parameter data bank): a new tool to investigate protein structure

A flexible package designed to study protein structure is described.The package is devoted to the analysis of protein sequencesby drawing structural profiles of specific structure-relatedamino acid parameters. An Aminoacidic Parameters Data Bank (CHAMP)containing 32 different series of physico-chemical parametersof amino acids is available. Sequences can be loaded from anyASCII format data bank or from keyboard. The program possessesa routine which enables easy updating of the protein data bankand CHAMP Data Bank. FAST reads statistical correlations betweentwo plots in order to identify structural similarities. Plotscan be printed, saved or used for correlation, comparison orgraph overlap by using common spreadsheets (e.g. Lotus 123).Plots can be smoothed by a running mean or a running median.The program also has a special feature—a global flexibilityanalysis of proteins. The package runs on IBM or compatiblesand requires DOS 3.0 or later. Received on June 20, 1989; accepted on August 2, 1989     

Possible role of 06-methylguanine-DNA-transferase in the response of patients with primary tumor of the brain to chemotherapy using chloro-ethyl-nitroso-urea: results of a current study

We have started a study to measure the MT activity in surgical specimens from high grade human malignant gliomas, with the dual aim to (i), know whether lack of activity can be demonstrated in these tumors, and (ii), relate the measured levels of MT to the histology of the tumors and to the response of patients to chemotherapy with 1-(2-Chloroethyl)-3-Cyclohexyl-1-Nitrosourea (CCNU). To date, 12 Gliomas have been assayed. In 11 tumors, MT activities ranging from 30 to 150 fmoles/mg protein have been measured. The only negative specimen derived from a patient who had received radiotherapy before surgery. At the present stage of the study, therefore, we have no unequivocal evidence for the existence of MT-deficient Gliomas.     

Effect of Glutathione and N-Acetylcysteine on in Vitro and in VIVO Cardiac Toxicity of Doxorubicin

The effects of two sulfhydryl compounds, glutathione (GSH) and N-acetylcysteine (NAC), on the cardiotoxicity of doxorubicin (DXR) were tested on in vitro and in vivo models. DXR was administered to rats as 4 weekly i.v. doses of 3mg/kg. GSH (1.5 mmoles/kg), given i.v. 10 min before and 1 hr after DXR, was found to prevent the development of the delayed cardiotoxic effects of DXR, as assessed by electrocardiographic and mechanical parameters, as well as by histological examination of left ventricular preparations. In contrast, equimolar oral doses of NAC (1 hr before and 2hrs after DXR) were found to be ineffective. Both GSH and NAC prevented the negative inotropic effect produced by DXR on isolated rat atria. A good correlation exists between the cardioprotective effects of the two agents and their ability to enhance the non-protein sulfhydryl group content of the myocardium. Differences observed in vivo between GSH and NAC might be accounted for by pharmacokinetic factors.     

Regional Reductions of Transketolase in Thiamine-Deficient Rat Brain

Abstract: Thiamine deficiency impairs oxidative metabolism and causes metabolic encephalopathy. An early reduction in transketolase (TK) activity may be an important pathogenic event. To assess the role of TK, we have delineated the regional/cellular distribution of TK protein and mRNA in adult rat brain in pyrithiamine-induced thiamine deficiency. TK activity declined in both vulnerable and spared regions. Immunoblots showed a parallel reduction of TK protein. With a few exceptions, immunocytochemistry indicated an overall decline of TK immunoreactivity and the decrease was not specific to vulnerable areas. In contrast to the pronounced, general decline of TK protein, in situ hybridization revealed a regional decrease of 0–25% of TK mRNA in thiamine deficiency. Northern blots indicated a similar level of TK mRNA in whole brain in thiamine deficiency. These results show that the decline of TK activity results from a proportional decrease of TK protein, and the deficiency may be due to an instability of TK protein or an inhibition of TK mRNA translation. The lack of correlation of the distribution, and the absence of specific alteration, of TK in affected regions suggest that the reduced TK may not be linked directly to selective vulnerability in thiamine deficiency.