Phosphate transport system inParacoccus denitrificans

P_i uptake in cells or spheroplasts ofParacoccus denitrificans is biphasic; only the first rapid phase represents net P_i transport. The second phase is limited by the rate of P_i utilization inside the cell, i.e., mainly by its esterification, and as such it was inhibited by DCCD. The P_i/dicarboxylate antiporter does not seem to be operative, and its inhibitorn-butylmalonate did not exert specific inhibition. P_i transport is inhibited by SH reagents; the most potent inhibitor is PCMB, and mersalyl is much less effective. However, neither inhibitor affects efflux of accumulated P_i. The gradient of potassium ions may be involved in the P_i uptake, which is lowered in the presence of valinomycin. FCCP alone does not release accumulated P_i from spheroplasts unless they are preincubated with SCN^?. The results indicate that P_i enters the cell by symport with protons.     

The relation between the synergistic effect of cytostatics and metabolism of V 79B cells in vitro.

A single-dose simultaneous application of methotrexate (MTX; 0.002/microgram ml-1) and cisplatin (cis-Pt; 0.0002/microgram ml-1) had a permanent synergistic effect on both synchronized and asynchronous cell populations of V 79B cells. Successive combination of the drugs was manifested synergistically when MTX was applied first. The synchronized cell population was more sensitive to the cytostatics than the asynchronous population. Treatment with MTX alone, or the combination of MTX-cis-Pt, as well as their successive combination with the first drug being cis-Pt, caused gluconeogenesis.     

Background Parenchymal Enhancement of the Contralateral Normal Breast: Association with Tumor Response in Breast Cancer Patients Receiving Neoadjuvant Chemotherapy

PURPOSE: This study investigated the association between background parenchymal enhancement (BPE) and pathologic response to neoadjuvant chemotherapy (NAC). METHODS: A total of 46 patients diagnosed with invasive breast cancer were analyzed. Each patient had three magnetic resonance imaging (MRI) studies, one pre-treatment and two follow-up (F/U) MRI studies. BPE was measured as the averaged enhancement of the whole fibroglandular tissues. The pre-treatment BPE and the changes in the F/U MRI were compared between patients achieving pathologic complete response (pCR) versus those not. Subgroup analyses based on age, estrogen receptor (ER), and human epidermal growth factor receptor 2 (HER2) status of their cancers were also performed. RESULTS: The pre-treatment BPE was higher in the pCR group than that in the non-pCR group. Compared to baseline, BPE at F/U-1 was significantly decreased in the pCR group but not in the non-pCR group. In subgroup analysis based on age, these results were seen only in the younger group (< 55 years old), not in the older group (≥ 55 years old). Older patients had a significantly lower pre-treatment BPE than younger patients. In analysis based on molecular biomarkers, a significantly decreased BPE at F/U-1 was only found in the ER-negative pCR group but not in the non-pCR, nor in the ER-positive groups. CONCLUSIONS: A higher pre-treatment BPE showing a significant decrease early after starting NAC was related to pCR in pre/peri-menopausal patients.     

Tryptophan synthase activity,tryptophan and serine contents in pea (Pisum sativum L.) plants during their ontogenesis

Considerable changes in tryptophan synthase aotivity occur during the ontogenesis of pea plants (Pisum sativum L.) in their individual parts. Maximal tryptophan synthase activity is connected with the vigorous growth period of the individual organs and of the entire plant. The content of free serine which is present in excess and is one of the substrates in the reaction catalyzed by tryptophan synthase, also changes, as well as the content of free tryptophan, the product of the reaction. The changes in the contents of these amino acids do not correspond to the variation in tryptophan synthase activity and mainly follow the alterations in the total nitrogen metabolísm. The limiting factor in the biosynthesis ofL-tryptophanin vivo is probably the availability of the aromatic precursor, above all of indole-3-glycerophosphate. The content of bound tryptophan also shifts in the pea plants owing to the enrichment of proteins in older parts of pea plants with this amino acid.     

Novel quercetin derivatives in treatment of peroxynitrite-oxidized SERCA1

Sarco/endoplasmic reticulum calcium ATP-ase (SERCA) is regulated by low concentrations of peroxynitrite and inhibited by high levels, as indicated in human diseases. We studied quercetin (Q) and its novel derivatives monochloropivaloylquercetin (MPQ) and chloronaphthoquinonequercetin (CHQ) as agents with expected preventive properties against peroxynitrite-induced SERCA impairment. Q and MPQ protected the SERCA1 against peroxynitrite induced activity decrease, while CHQ potentiated the inhibitory effect of peroxynitrite. Quercetin derivatives were found to be weaker antioxidants compared with Q, as indicated by their ability to scavenge peroxynitrite and prevent of SERCA1 carbonylation, both decreasing in the order (Q > MPQ > CHQ). Quantum-chemical values of theoretical parameter E _HOMO also indicated lower antioxidant capacities for MPQ and CHQ. Prooxidant properties estimated by calculations of frontier molecular orbitals (E _LUMO) correlated with experimentally determined SH-group decrease induced by the compounds studied. Both methods showed a decrease of prooxidant properties as follows: CHQ > MPQ > Q. In addition, experimentally measured half-wave potentials indicated stronger prooxidant properties of quercetin derivatives as compared to Q. More expressive alterations of conformation in the transmembrane region of SERCA1 induced by quercetin derivatives, as compared with Q, may at least partially correlate with their higher lipophilicities. The protective effects of Q and MPQ on different isoforms of SERCA activity may be useful in prevention and treatment of inflammation or muscle diseases. The inhibitory effect of CHQ on SERCA isoforms may be beneficial in therapeutic approaches aimed at anti-tumor treatment.     

Physical fitness of the Czechoslovak population between the ages of 12 and 55 years. Oxygen consumption and pulse oxygen.

The authors measured oxygen consumption in a Czechoslovak population aged from 12 to 55 years. An abrupt increase was found between 12 and 18 years, when the maximum was reached (males 3.28, females 2.17 l/min), followed by a slower decrease to 55 years. Relative O2 consumption (per kg body weight) showed a continuous decrease from 12 years, when maximum values were recorded (49 ml/min . kg for boys, 46 ml/min . kg for girls), to 55 (33 ml/min . kg for males, 27 ml/min . kg for females). In the adult population (18--55 years), no differences were observed in the values at the various levels of submaximal loading. The pulse oxygen attained the maximum at 18 (males 16.8, females 11 ml).     

Cholinesterase activity in quail primary lymphoid organs

The present histochemical study was carried out to analyze the distribution and topography of acetylcholinepositive nerve fibers in the thymus and bursa of Fabricius of quails. The AChE-positive nerve fibers were demonstrated by direct thiocholine histochemical method. Nerve fibers present in the thymuses form periarterial nerve plexuses located mostly in the interlobular septa and on the cortico-medullary junction. Vessels-independent nerve fibers occur also in the parenchyma of thymic medulla, but rarely in parenchyma of the cortex. Within the connective tissue between the bursa of Fabricius and the wall of proctodeum we observed conspicuous AChE-positive ganglia, often in close relationship to greater arteries. Within the wall of bursa of Fabricius, AChE-positive nerve fibers create nerve plexuses around arteries. We observed a close relationship between lymphoid follicules in bursal submucosa and mucosa and AChE-positive nerve fibers. Nerve fibers create a ring around lymphoid follicles, but do not penetrate into the germinal center of the follicle. Arteries inside quail thymuses and bursae of Fabricius contain rich AChE-positive nerve plexuses, when compared to the veins, which have a very poor presence of AChE-positive nerves. According to lesser presence and decreased density of AChE-positive nerve fibers in older animals, we described age-dependent changes in both quail primary lymphoid organs.     

The effect of phonation into a straw on the vocal tract adjustments and formant frequencies. A preliminary MRI study on a single subject completed with acoustic results

Phonation into a straw is used in voice training and therapy. This study investigated its’ effects on the vocal tract adjustments.Magnetic resonance images were taken from one female phonating first on [a:], then into a plastic drinking straw and then again on [a:]. Acoustic samples were recorded from her and 10 other females. The samples were analyzed for fundamental frequency, sound pressure level (SPL), five lowest formant frequencies (F₁–F₅) and SPL of the speaker's formant cluster range (2.5–4.5 kHz).During and after phonation into a straw, the midsagittal area of the vocal tract increased and the velar closure improved. The ratio of the transversal area of the lower pharynx over that of the epilarynx increased both during (27%) and after the straw (20%). The overall SPL and the SPL of the speaker's formant cluster increased. The frequencies of F₂, F₄ and F₅ decreased, while F₃ increased. The distances between F₄ and F₃ and F₅ and F₄ decreased by 49%. For the 10 subjects, F₃ increased, F₄ decreased and the distance between F₃ and F₄ decreased significantly.The results suggest that exercising with a straw helps establishing a speaker's formant cluster, which increases loudness and thus improves vocal economy.     

Free Radicals in Rabbit Spinal Cord Ischemia: Electron Spin Resonance Spectroscopy and Correlation with SOD Activity

1. In nonanesthetized rabbits temporal occlusion of the abdominal aorta was used to induce oxidative stress in the lower part of the body including distal segments of the spinal cord.2. Spinal cord samples were taken from the animals exposed to 25-min aortic occlusion (AO ) or to occlusion followed by 1- or 2-hr reperfusion (AO/R1 or AO/R2, respectively) or from sham-operated animals (C). The presence of free radicals (FR) in the spinal cord samples frozen in liquid N₂ was assessed by ESR spectroscopy without spin trapping. Moreover, superoxide dismutase (SOD) activity and conjugated diene (CD) levels were measured in the samples.3. In the AO group FR were detected in the spinal cord regions close to the occlusion (lower thoracic and distal segments) along with a decrease in SOD activity. The calculated g value (g = 2.0291) indicated that the paramagnetic signal recorded might be attributed to superoxide radicals. FR were absent in the AO/R1 group. Concurrently, the SOD activity revealed a significant tendency to return to the control level. FR appeared again in the AO/R2 group, mostly in the upper and middle lumbar regions, along with a decrease in SOD activity. No sample from the C group revealed FR. A significant increase in CD levels was observed in the thoracolumbar region only in the AO/R2 group. The temporary absence of FR in the AO/R1 group suggests activation of defense antioxidant mechanisms (e.g., specific enzymatic systems such as SOD), which might have been exhausted later.4. Changes in SOD activity similar to those observed in the thoracolumbar region, though less noticeable, occurred in the obviously noncompromised tissue (upper cervical region). This points to a kind of generalized reponse of the animal to aortic occlusion.5. Direct ESR spectroscopy revealed the presence of FR as well as their time course in the spinal cord during the early phase of ischemia/reperfusion injury and the inverse relationship between FR and SOD activity.     

Time course of lipid peroxidation during incomplete ischaemia followed by reperfusion in rat brain

The time course of lipid peroxidation was studied in the rat brain cortex after ischaemia and reperfusion. The ischaemia was induced by 4-hour occlusion of both common carotid arteries and was followed by reperfusion of different duration (10, 30 or 60 min). The extent of lipid peroxidation was determined by measurement of conjugated dienes (CD) and TBA reactive products. Maximal values of CD and TBA reactive products were found after 10- and 30-minute reperfusion. This indicated the most suitable time interval for studying the effect of antioxidants and oxygen radical scavengers in this model of brain ischaemia.