Microwave Spectroscopy of Myocardial Ischemia and Infarction. 2. Biophysical Reconstruction

The proposed dielectrical relaxation model of the myocardium in the microwave spectrum has been verified both on test solutions and on normal canine myocardium. Furthermore, the model was utilized to reconstruct the changes in tissue properties (including myocardial bulk resistance and water content) following myocardial acute ischemia and chronic infarction. It was shown that the reconstructed myocardial resistance and water content correlate dynamically with the process of the development of acute myocardial ischemic injury. In chronic cases the reconstructed resistance and water content of infarcted myocardium are significantly different from that of normal myocardium: the resistance is lower and water content is higher than in normal myocardium. © 2000 Biomedical Engineering Society. PAC00: 8764-t, 8719Xx     

Localisation of CEA, β-HCG,SP1, and keratin in the tissue of lung carcinomas

Summary One hundred and twenty seven cases of lung tumors were studied by the immunoperoxidase technique for the presence of CEA and-HCG. Twenty-nine of these tumors were additionally stained for keratin and SP1. CEA and SP1 could be demonstrated in 80% of the studied cases, while-HCG was found in only 9%. SP1 revealed an almost identical staining pattern to CEA and keratin was found only in squamous cell carcinomas. The tissue positivity of none of these three markers correlated with tumor size, lymphnodal involvement or histological type.This study was supported by Deutsche Stiftung für Krebsforschung - Dr. Mildred Scheel-Stiftung     

DNA damage in cytologically normal urothelial cells of patients with a history of urothelial cell carcinoma

In order to determine if patients with a history of previous urothelial cell carcinoma (UCC) but with current normal urinary cytology have DNA damage in urothelial cells, the single-cell gel electrophoresis (comet) assay was conducted with cells obtained by urinary bladder washings from 44 patients (28 with a history of previous UCC). Increased DNA damage was observed in cytologically "normal" urothelial cells of patients with a history of UCC when compared with referents with no similar history and after correcting the data for smoking status and age (P < 0.018). Increased DNA damage also correlated with the highest tumor grade, irrespective of time or course of the disease after clinical intervention (Kendall tau correlation, 0.37, P = 0.016). Moreover, aneuploidy, as assessed by DNA content ratio (DCR; 75th/25th percentile of total DNA fluorescence of 50 comets/patient) was unaltered by smoking status, but increased with UCC grade: 1.39 +/- 0.12 (median +/- 95% confidence interval; referents); 1.43 +/- 0.11 (Grade I UCC; P = 0.264, against referents); 1.49 +/- 0.16 (Grade II UCC; P = 0.057); 1.57 +/- 0.16 (Grade III UCC; P = 0.003). Micronucleated urothelial cells (MNC) were also scored on Giemsa-stained routine cytological smears and were found not to correlate with DNA damage or DCR. MNC frequencies were higher for patients with a history of UCC and/or smoking than referents with neither history, but there was no statistical difference between groups. Taken together, these results suggest that the normal-appearing urothelium of patients resected for UCC still harbor genetically unstable cells.     

Amino-acid alterations in the β-tubilin gene of Neurospora crassa that confer resistance to carbendazim and diethofencarb

We have previously shown that increased sensitivity to diethofencarb in the carbendazim(MBC)-resistant F914 strain of Neurospora crassa is caused by a single amino-acid change in -tubulin, ¹⁹⁸Glu to Gly. Three diethofencarb-resistant mutants that are also resistant to MBC were isolated from strain F914. They contained single base-pair-substitution mutations in the -tubulin gene. The amino acid changes in -tubulin, Phe from ²⁵⁰Leu, Val from ¹⁶⁵Ala, and Ala from ²³⁷Thr, were responsible for diethofencarb-resistance in the mutant strains FR511, FR513, and FR421, respectively. The amino acid at position 198 of -tubulin in these mutants was Gly, which is the same as in strain F914. -tubulin genes with ¹⁹⁸Glu were constructed by site-directed mutagenesis. The altered -tubulin genes derived from FR511 and FR421 transformed the wild-type strain to resistance to MBC, indicating that ²⁵⁰Phe and ²³⁷Ala in -tubulin are responsible for resistance not only to diethofencarb but also to MBC.     

The nonselective cation channel in the basolateral membrane of rat exocrine pancreas

Nonselective Ca²⁺-sensitive cation channels in the basolateral membrane of isolated cells of the rat exocrine pancreas were investigated with the patch clamp technique. With 1.3 mmol/l Ca²⁺ on the cytosolic side, the mean openstate probabilityP _o of one channel was about 0.5. In insideout oriented cell-excised membrane patches the substances diphenylamine-2-carboxylic acid (DPC), 5-nitro-2-(3-phenylpropylamino)-benzoic acid (NPPB) and 3,5-dichlorodiphenylamine-2-carboxylic acid (DCDPC) were applied to the cytosolic side. These compounds inhibited the nonselective cation channels by increasing the mean channel closed time (slow block). 100 mol/l of NPPB or DPC decreasedP _o from 0.5 (control conditions) to 0.2 and 0.04, respectively, whereas 100 mol/l of DCDPC blocked the channel completely. All effects were reversible. 1 mmol/l quinine also reducedP _o, but in contrast to the abov mentioned substances, it induced fast flickering. Ba²⁺ (70 mmol/l) and tetraethylammonium (TEA⁺; 20 mmol/l) had no effects. We investigated also the stilbene disulfonates 4-acetamido-4-isothiocyanatostilbene-2,2-disulfonic acid (SITS), 4,4-diisothiocyanatostilbene-2,2-disulfonic acid (DIDS) and 4,4-dinitro-2,2-stilbenedisulfonate (DNDS). 10 mol/l SITS applied to the cytosolic side increasedP _o from 0.5 to 0.7 and with 100 mol/l SITS the channels remained nearly permanently in its open state (P _o1). A similar activation of the channels was also observed with DIDS and DNDS. These effects were poorly reversible. The stilbene disulfonates acted by increasing the channel mean open time. When the channel was inactivated by decreasing bath Ca²⁺ concentration to 0.1 mol/l, addition of 100 mol/l of SITS had no effect. Similarly, reducing bath Ca²⁺ concentration from 1.3 mmol/l in presence of 100 mol/l SITS (channels are maximally activated) to 0.1 mol/l, inactivated the channels completely. These results demonstrate, that SITS can only activate the channels in the presence of Ca²⁺. SITS had no effects, when applied to the extracellular side in outside out patches. In summary, the substances DPC, NPPB and DCDPC inhibit nonselective cation channels, where DCDPC has the most potent and NPPB the smallest effect; whereas SITS, DIDS and DNDS activate the channel when applied from the cytosolic side in the presence of Ca²⁺ ions.     

Control of pulmonary vascular smooth muscle tone by sarcoplasmic reticulum ca2+ pump blockers: thapsigargin and cyclopiazonic acid

The effect of thapsigargin (TG) and cyclopiazonic acid (CPA) on the mechanical activity of the rat pulmonary artery were investigated. In chemically (-escin)-skinned arterial strips, application of TG (0.1–1 M) or CPA (0.5–10 M) prior and throughout the loading procedure of the internal Ca²⁺ stores (0.3 M free Ca²⁺ ions for 8–10 min) concentration dependently inhibited the subsequent contractile response induced by noradrenaline (NA, 10 M) or caffeine (25 mM). In intact strips repeatedly incubated in a Ca²⁺-containing solution (2.5 mM for 10 min), followed by incubation in a Ca²⁺-free solution 12 min before NA-stimulation, TG and CPA not only inhibited the NA-induced contraction but also increased the tension which appeared during the exposure time to Ca²⁺. The two phenomena developed with similar time courses. The increase in tension during the readmission of Ca²⁺ ions was not antagonized by verapamil (10 M) or nifedipine (1 M) but was blocked by La³⁺ (50 M) and Co²⁺ (1 mM) ions. The amplitude of the verapamil-insensitive TG (or CPA)-induced contraction was dependent on the external [Ca²⁺] [0.1–10 mM, concentration for half maximal effect (EC₅₀) =0.85 mM], not modified by the reduction of the external [Na⁺] (from 130 to 10 mM) and decreased by depolarization of the strip using K⁺-rich (30–120 mM) solutions. Under the latter condition, 38±9 and 83±4% reduction (n=5) was observed in the presence of 60 and 120 mM K⁺ respectively. This contraction was also concentration dependently inhibited by the tyrosine kinase inhibitors genistein (0.5–50 M) and tyrphostin (2–50 M). Sr²⁺ ions, which contracted both depolarized intact and skinned strips, failed to replace Ca²⁺ ions in the verapamil-insensitive contraction induced by TG or CPA (n=4). Finally, TG (1 M) and CPA (10 M) did not modify the pCa tension relationship in skinned strips (n=5). These results show that the main action of TG and CPA in rat pulmonary artery is to prevent the refilling of the internal Ca²⁺ store. TG and CPA also seem to facilitate a Ca²⁺ influx through a specific verapamil-insensitive pathway. The biophysical and molecular characteristics of this pathway remain to be elucitated, although it appears to involve a tyrosine kinase activity.     

Cloning of the PYR4 gene encoding orotidine-5′-phosphate decarboxylase in Cephalosporium acremonium

Summary We have cloned the Cephalosporium acremonium pyr4 gene by cross-hybridization with the equivalent gene from Neurospora crassa, the closest relative from which this gene is available. The C. acremonium pyr4 gene complements an E. coli pyrF mutant lacking orotidine-5-phosphate decarboxylase (OMPdecase), and most probably does not contain introns. Maxicell analysis in E. coli shows that it encodes a 46 kDa polypeptide. The C. acremonium OMPdecase contains a highly conserved pentadecapeptide characteristic for this category of enzyme. Extensive sequence comparison suggests an important role of this region in enzymatic activity.     

Effect of injury to the zone of the medial forebrain bundle and preoptic region on activity of an epileptiform focus induced by penicillin (on the phenomenon of the hyperactive determinant dispatch station)

Experiments on cats showed that injury to the medial forebrain bundle (MFB) and also partly to the preoptic region on the side of application of penicillin to the cerebral cortex (middle suprasylvian gyrus) causes depression of paroxysmal activity (spike potentials) in the penicillin focus, and also in a secondary mirror focus arising in the symmetrical zone of the opposite cortex. Injury to MFB on the side of the mirror focus causes depression of paroxysmal spike potentials only in that focus and does not affect activity in the primary epileptiform focus. The effects described are examined from the standpoint of views regarding the role of the determinant dispatch station (DDS) in the activity of the CNS: A primary epileptiform focus is a hyperactive DDS which induces the appearance of secondary foci, supports them, and determines the character of their activity. The results of the investigation suggests a role for MFB in the modulation of cortical epileptiform activity.Laboratory of General Pathology of the Nervous System, Institute of General Pathology and Pathophysiology, Academy of Medical Sciences of the USSR, Moscow. Laboratory of Electrophysiology, V. F. Filatov Odessa Research Institute for Eye Diseases and Tissue Therapy, Ministry of Health of the Ukrainian SSR. Translated from Byulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 82, No. 12, pp. 1413–1416, December, 1976.     

Effect of avitaminosis B6 in mice on T-lymphocyte function in vitro

The effect of different degrees of avitaminosis B₆ in mice on the cytolytic activity of T lymphocytes, measured as the quantity of Na₂Cr⁵¹O₄ released from lysed target cells, was studied on a model of the primary immune response in a mixed lymphocyte culture in vitro. Keeping animals for 3 weeks on a diet without pyridoxine did not affect the ability of the lymphocytes to proliferate in vitro or their cytolytic activity. In animals receiving a diet without pyridoxine for 45 days the content of pyridoxal-5-phosphate in the spleen was 55% lower than in the control. Lymphocytes taken from these animals, when cultured in vitro, showed sharply weakened ability to incorporate [³H]thymidine into DNA in response to the alloantigen. The cytolytic activity of these lymphocytes also was reduced. The ability of different forms of pyridoxine to restore the functions of T lymphocytes, when disturbed by avitaminosis B₆, was studied.Laboratory of Systemic Blood Diseases, Oncologic Scientific Center, Academy of Medical Sciences of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR N. A. Kraevskii.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 84, No. 8, pp. 185–188, August, 1977.     

Intratumorous distribution of catecholaminergic clone cells of human neuroblastoma

Summary The intratumorous distribution of catecholaminergic clone cells in 23 human neuroblastomas was studied using Falck-Hillarp's method, and the findings compared with the catecholamine (CA) content within the tumour. All the specimens contained elements with CA fluorescence, and the pattern of fluorescence was classified from the distribution of CA-positive cells and neurofibrils, as diffuse cellular (DC); diffuse fibrillary (DF), sporadic (S), clustered (C), island-shaped (I), and bundled (B). The strength of CA fluorescence of both cellular and fibrillary elements correlated well with the CA content within the tumour. In addition, all tumours of urinary VMA-negative cases also contained significantly larger amounts of CA than other, non-functioning, tumours in the paediatric age group. The results of this study suggest that firstly, the ratio of CA-positive cells to CA-positive neuronal processes is proportionately higher in the poorly-differentiated neuroblastomas and that secondly, even tumours negative for urinary VMA or HVA might be polyclonal and contain catecholaminergic elements.This study was supported in part by a Research Grant from the Ministry of Education, Japan (No. 59570549)