Electrical injury mechanisms: dynamics of the thermal response

The thermal response of the human upper extremity to large electric currents was examined using an axisymmetric unidimensional model containing bone, skeletal muscle, fat, and skin in coaxial cylindrical geometry. Appropriate thermal and electrical properties were assigned to each tissue, and the tissue response to joule heating was determined by a finite-element numerical technique. We found that when the tissues are electrically in parallel, skeletal muscle sustained the largest temperature rise and then heated adjacent tissues. Thus, when bone is not in series with other tissues, joule heating of bone is unlikely to be responsible for thermal damage to adjacent tissue. In addition, the effect of tissue perfusion on the thermal response was found to be essential for rapid cooling of the centrally located tissues.     

Acute and delayed vasoconstriction after subarachnoid hemorrhage: local cerebral blood flow, histopathology, and morphology in the rat basilar artery.

The decreased local cerebral blood flow (LCBF) and cerebral ischemia that occur after subarachnoid hemorrhage (SAH) may be caused by acute and/or delayed vasospasm. In 36 Sprague-Dawley (350-450 g) rats SAH was induced by transclival puncture of the basilar artery. Mean arterial blood pressure (MABP), LCBF, intracranial pressure (ICP), and cerebral perfusion pressure (CPP) were measured in all rats for 30 min before and 60 min after SAH was induced. One set of control (n : 7) and experimental animals (n : 7) was sacrificed after the 60 min of initial post-hemorrhage measurements were recorded. Four days after SAH induction, LCBF and MABP were measured again for 60 min in subgroups of surviving experimental rats (n : 7) and control rats (n : 7). Histopathologic and morphologic examinations of the basilar artery were performed in each subgroup. There was a sharp drop in LCBF just after SAH was induced (55.50 +/- 11.46 mlLD/min/100 g and 16.1 +/- 3.6 mlLD/min/100 g for baseline and post-SAH, respectively; p < 0.001). The flow then gradually increased but had not returned to pre-SAH values by 60 min (p < 0.05). At 4 days after SAH induction, although LCBF was lower than that observed in the control group and pre-SAH values, it was not significantly different from either of these flow rates (p > 0.05). ICP (baseline 7.05 +/- 0.4 mmHg) increased acutely to 75.2 +/- 7.1 mmHg, but returned to normal levels by 60 min after SAH. CPP (baseline 84.5 +/- 6.3 mmHg) dropped accordingly (to 18.6 +/- 3.1 mmHg), and then increased, reaching 72.2 +/- 4.9 mmHg at 60 min after SAH (p > 0.05). Examinations of the arteries revealed decreased inner luminal diameter and distortion of the elastica layer in the early stage. LCBF in nonsurviver rats (n : 8) was lower than that in the animals that survived (p < 0.01). At 4 days post-hemorrhage, the rats' basilar arteries showed marked vasculopathy. The findings showed that acute SAH alters LCBF, ICP, and CPP, and that decreased LCBF affects mortality rate. Subsequent vasculopathy occurs in delayed fashion, and this was observed at 4 days after the hemorrhage event.     

Electrical injury mechanisms: electrical breakdown of cell membranes

Electric fields are capable of damaging cells through both thermal and nonthermal mechanisms. While joule heating is generally recognized to mediate tissue injury in electrical trauma, the possible role of electrical breakdown of cell membranes has not been thoroughly considered. Evidence is presented suggestive that in many instances of electrical trauma the local electrical field is of sufficient magnitude to cause electrical breakdown of cell membranes and cell lysis. In theory, large cells such as muscle and nerve cells are more vulnerable to electrical breakdown. To illustrate the significance of cell size and orientation, a geometrically simple model of an elongated cell is analyzed.     

Agarose gel electrophoresis in isozyme separation and visualization

Isozyme analysis of rodent-human somatic cell hybrids has been used frequently to detect specific human chromosomes. The majority of these isozyme systems employs starch gels, the use of which can be laborious when screening large numbers of cell lines. We describe the development of two procedures to detect the long arms of human chromosomes 1 and 2 in Chinese hamster-human cell hybrids by a rapid and reproducible method using 1-mm-thick agarose gels. Detection of human chromosome 1q was accomplished by screening for human fumarate hydratase activity, whose gene has been mapped to 1q42.1. Detection of chromosome 2q was performed by screening for the isozyme isocitrate dehydrogenase 1, which has been localized to 2q32-qter. These systems provide a basis for the further development of procedures for detecting chromosome-specific isozyme markers in agarose gels.     

The benthic phase of the life cycle ofParapenaeus longirostris (Crustacea,Decapoda, Penaeidae) along the Mediterranean coast of Israel

The population ofP. longirostris along the Mediterranean coast of Israel spends the benthic phase of its life cycle (from body size over 15 mm) on muddy bottom deeper than 45 m. New age groups are recruited within the depth zone of 45–300 m and migrate in both inshore and offshore directions. Inshore migration is limited by unsuitable sandy ground. The limiting line for offshore migration was not found.An age group could be detected during one year within a body size range of TL = 40 mm to TL = 84.5 mm for males and to TL = 102.5 mm for females. Reproductive activity in shallow water, down to a depth of 73 m, takes place during the whole year, while in depths of 150–300 m there is an arrest of reproductive activity from June to August.     

The pathogenesis of trehalose dimycolate-induced interstitial pneumonitis: III. Evidence for a role for T lymphocytes

Trehalose dimycolate, a glycolipid component of the cell walls of mycobacteria, induces interstitial pneumonitis and alveolar hemorrhages in C57BL/6 and C57BL/10 mice. Homozygous nude (nu/nu) mice of these backgrounds are not susceptible to this form of pulmonary injury. However, after administration of T-lymphocyte-enriched spleen cell preparations from syngeneic donors, homozygous nude mice become susceptible to trehalose dimycolate. The observations suggest that production of pulmonary lesions by this mycobacterial component is dependent on T lymphocytes. While the mechanisms are still under study, we propose that trehalose dimycolate can function as an activator of T lymphocytes and that products of activated T cells are responsible for production of the pulmonary lesions.     

Anatomical aspects of hormonal regulation of abscission in citrus – The shoot-peduncle abscission zone in the non-abscising stage

Although mature citrus fruits [ Citrus sinensis (L.) Osbeck cv. Shamouti] did not abscise at the peduncle-shoot abscission zone (AZ–A) when incubated in ethylene environment, abscission processes did occur in a limited number of cell layers situated in the inner bark, the starch sheath region, and in the pith of AZ–A. These processes were regulated by 2,4-D and ethylene treatments. Cells responding to the "separation processes", particularly in the ethylene treatment, underwent either (a) cell wall swelling, dissolving and breakdown, or (b) growth and expansion in a radial plane. Further away from the dissolving area, the response of some cells of the mid and outer bark took the form of divisions or growth in a circumferential plane, while other cells remained unchanged. Non-responding tissues of the outer bark formed a "sleeve" of undissolved cells, and the vascular cylinder produced no abscission in AZ–A. It is concluded that the partial cell wall dissolution in AZ–A explains the increased activity of cellulase and polygalacturonase in the non-abscising AZ–A of the mature fruit (Greenberg et al. 1975. Physiol. Plant. 37: 1–7).     

Propolis Enhances 5-Fluorouracil Mediated Antitumor Efficacy and Reduces Side Effects in Colorectal Cancer: An in Vitro and in Vivo Study

In this study, we investigated the combined treatment of 5-fluorouracil (5-FU) and Anatolian propolis extract (PE) on colorectal cancer (CRC)using in vitro and in vivo studies. We exposed luciferase-transfected (Lovo-Luc CRC) cells and healthy colon cells (CCD-18Co) to varying concentrations of 5-FU and PE to assess their genotoxic, apoptotic, and cytotoxic effects, as well as their intracellular reactive oxygen species (iROS) levels. We also developed a xenograft model in nude mice and evaluated the anti-tumor effects of PE and 5-FU using various methods. Our findings showed that the combination of PE and 5-FU had selectivity against cancer cells, particularly at higher doses, and enhanced the anti-tumor effectiveness of 5-FU against colon CRC. The results suggest that PE can reduce side effects and increase the effectiveness of 5-FU through iROS generation in a dose-dependent manner.