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Biomedical subjects

J Petrovic

Publications and source records attributed to J Petrovic.

11 recordsLinked to original sources

Salvage rectal surgery--overview.

Recurrence of the disease represents the major problem in patients who undergo "curative" resection for rectal cancer, with published rate ranging from 3 to 50%. Most relapses occur within first two years of follow-up. Depending on the site of the recurrence, it can be local or distant. It also can be solitary or diffuse. In terms of potential surgical cure the best results are achieved with solitary, localized metastases. The most common sites of the solitary metastases are pelvis, liver and lung, with a fairly even distribution among these three sites. Other sites of the localized metastases can be peritoneum, lymph nodes, brain, bone, abdominal wall, ureter and kidney. These sites are less common, but not so amenable to resection. Local recurrence varies depending on the original type of surgery. It can be stated that surgical technique directly influences local recurrence rate in patients with rectal cancer. According to the results from a number of different authors 5-year survival rate after reresection is 2-13% of all patients with locally recurrent cancer, both alone and associated with distant metastases. The most important moment in this problem is to decide when not to operate. The absolute contraindications for salvage surgery are: "frozen pelvis", aneuploid tumors and those with mucinous component, clinical or CT evidence of invasion of the pelvic nerves, lymphatics or veins, or ureter bilaterally. Also, evidence of involvement of the lateral pelvic sidewalls and/or upper sacral marrow, and/or S2 is an absolute contraindication for surgery. Thus, main goals of this type of surgery are respectively: palliation of symptoms, a good quality of life and, if possible, cure with low treatment-related complication rates.

Humans↗

Nanofabricated media with negative permeability at visible frequencies.

A great deal of attention has recently been focused on a new class of smart materials--so-called left-handed media--that exhibit highly unusual electromagnetic properties and promise new device applications. Left-handed materials require negative permeability micro, an extreme condition that has so far been achieved only for frequencies in the microwave to terahertz range. Extension of the approach described in ref. 7 to achieve the necessary high-frequency magnetic response in visible optics presents a formidable challenge, as no material--natural or artificial--is known to exhibit any magnetism at these frequencies. Here we report a nanofabricated medium consisting of electromagnetically coupled pairs of gold dots with geometry carefully designed at a 10-nm level. The medium exhibits a strong magnetic response at visible-light frequencies, including a band with negative micro. The magnetism arises owing to the excitation of an antisymmetric plasmon resonance. The high-frequency permeability qualitatively reveals itself via optical impedance matching. Our results demonstrate the feasibility of engineering magnetism at visible frequencies and pave the way towards magnetic and left-handed components for visible optics.

Journal Article↗

Detection and imaging of atmospheric radio flashes from cosmic ray air showers.

The nature of ultrahigh-energy cosmic rays (UHECRs) at energies >10(20) eV remains a mystery. They are likely to be of extragalactic origin, but should be absorbed within approximately 50 Mpc through interactions with the cosmic microwave background. As there are no sufficiently powerful accelerators within this distance from the Galaxy, explanations for UHECRs range from unusual astrophysical sources to exotic string physics. Also unclear is whether UHECRs consist of protons, heavy nuclei, neutrinos or gamma-rays. To resolve these questions, larger detectors with higher duty cycles and which combine multiple detection techniques are needed. Radio emission from UHECRs, on the other hand, is unaffected by attenuation, has a high duty cycle, gives calorimetric measurements and provides high directional accuracy. Here we report the detection of radio flashes from cosmic-ray air showers using low-cost digital radio receivers. We show that the radiation can be understood in terms of the geosynchrotron effect. Our results show that it should be possible to determine the nature and composition of UHECRs with combined radio and particle detectors, and to detect the ultrahigh-energy neutrinos expected from flavour mixing.

Journal Article↗

Antibacterial activity of Cichorium intybus.

Antibacterial activity of the water, ethanol and ethyl acetate extracts of Cichorium intybus was investigated. All the tested extracts showed antibacterial activity, the ethyl acetate extract being the most active. Water extract inhibits Agrobacterium radiobacter sp. tumefaciens, Erwinia carotovora, Pseudomonas fluorescens and P. aeruginosa.

Anti-Bacterial Agents↗

Age-related progressive brachial artery endothelial dysfunction precedes the changed carotid and left ventricular geometry in healthy humans.

In this study the authors evaluated correlation between aging and brachial endothelial and vascular smooth muscle dysfunction, changes in carotid geometry, and left ventricular remodeling. Vasomotor influences of brachial endothelium and brachial smooth muscle function to reactive hyperemia and nitroglycerin (400 microg, sublingual spray) were assessed by noninvasive ultrasound in 66 healthy subjects of different ages (20-82 years). Carotid intima-media thickness and left ventricular mass index were also assessed by ultrasound and compared with brachial hemodynamic parameters. All results were analyzed by linear regression analysis. The response of brachial artery diastolic diameter to reactive hyperemia decreased with aging (p<0.0001). Also, the response of brachial artery diastolic diameter to nitroglycerin increased relative to aging (p<0.004). Age-related correlations between increased carotid intima-media thickness and brachial artery diastolic diameter response to reactive hyperemia (p<0.01) as well as between increased carotid intima-media thickness and increased left ventricular mass index (p<0.001) were found. However, there was no correlation between brachial artery diastolic diameter response to reactive hyperemia and increased left ventricular mass index (p>0.05). The study showed that aging influences not only brachial endothelial vasomotor properties but also vascular and cardiac geometry. The authors believe that modern therapeutic approach should take these results into consideration to establish new vasculo-protective and cardioprotective strategies.

Adult↗

Biochemical studies of the renal radiopharmaceutical compound dimercaptosuccinate. IV. Interaction of 99mTc-DMS and 99Tc-DMS complexes with blood serum proteins.

As a crucial step towards understanding the mechanism of localisation of radiopharmaceuticals in specific target organs, the interaction of the radiopharmaceuticals 99mTc-DMS and 99Tc-DMS with blood serum proteins was studied. The interaction of 99mTc-DMS radiopharmaceutical was examined from two aspects: total protein binding as well as specificity of binding to certain classes of proteins. After in vitro labelling of human sera with 99mTc-DMS, the following values of bound radioactivity to total serum proteins were determined: 65% +/- 3.2% by gel-filtration chromatography; 72% +/- 4.6% by dialysis; while on the basis of precipitation by perchloric and trichloroacetic acid 72.7% +/- 6.8% and 71% +/- 2.3%, respectively. Distribution of 99mTc-DMS or 99Tc-DMS among serum proteins was analysed by agarose gel electrophoresis of the sera at pH 8.6 after in vivo and in vitro labelling of human sera with 99m-Tc-DMS, while the same analysis was performed with 99Tc-DMS complex after in vitro labelling of human and rat sera as well as after in vivo application to the rats. The results obtained demonstrate that carrier serum proteins investigated by agarose gel electrophoresis were in the migration zone of alpha 2-, alpha 1- and beta 1-globulins, whereas the radioactivity found in the serum albumin zone was negligible. Interaction of both Tc-DMS complexes with proteins was very similar, and this conclusion was in good correlation with our previously obtained results in investigations concerning the biochemical behaviour of these complexes.

Alpha-Globulins↗

Characterization of the DNA in Drosophila melanogaster.

DNA has been quantitatively extracted from Drosophila melanogaster at various stages of embryonic development and analyzed by isopycnic centrifugation in CsCl and by fractionation on methylated albumin columns. The DNA is composed of three main classes of DNA, as defined by their buoyant density, rho, in CsCl: a bulk DNA, rho = 1.699 g cm(-3), and two satellite DNAs, rho = 1.685 g cm(-3) and rho = 1.669 g cm(-3). These three types of DNA persist throughout the development of the insect. In the unfertilized egg, 80% of the total DNA consists of the satellite DNAs; this amount decreases to 18% during the first three hours after fertilization and then remains constant through embryogenesis. There is a concomitant increase of the satellite DNA's with the bulk DNA after blastoderm formation.

Animals↗

Satellite DNAs in the embryos of various species of the genus Drosophila.

A tentative evolutionary pattern has been found for two classes of the multiple satellite DNA's found in the genus Drosophila. The satellite DNA's from five Drosophila species (D. melanogaster, D. simulans, D. nasuta, D. virilis and D. hydei) were analyzed and found to fall into three arbitrary CsCl buoyant density classes: Class I, rho = 1.661-1.669 g cm(-3), DNA molecules composed of primarily dA and dT moieties; Class II, rho = 1.685 and rho = 1.692, DNA molecules of low GC content; and Class III, rho = 1.711, a DNA of high GC composition. The dAT satellite DNA's appear in all the species studied except D. hydei, the species of most recent evolutionary divergence, whereas the heavy satellite appears only in the two species of most recent divergence, D. virilis and D. hydei.

Animals↗

Inhibition of the proteasome reduces transfer-induced diabetes in nonobese diabetic mice.

Inhibition of the 26S proteasome reduces the severity of several immune-mediated diseases. Here, we report that the proteasome also regulates transfer-induced diabetes in nonobese mice. Treatment of recipient mice with the proteasome inhibitor N(alpha)-benzyloxycarbonyl-l-leucyl-l-leucyl-l-leucinal (MG132) resulted in a 76% reduction in transfer-induced diabetes. The closely related inhibitor carbobenzoxy-l-leucyl-l-leucinal that inhibits calpains but not the proteasome had no protective effect, suggesting that MG132 acted via inhibition of the proteasome. MG132 decreased proliferation of transferred T cells in the pancreatic lymph nodes in vivo and prevented their expansion in a dose-dependent manner in vitro, consistent with a direct effect by MG132 on the T cells. MG132 did not prevent migration of transferred T cells into the islets but reduced the number of mice with severe infiltration. We suggest that MG132 prevents transfer-induced diabetes by directly targeting the autoreactive T cells and lowering their diabetogenic potential.

Adoptive Transfer↗