The topoisomerase II alpha gene status in primary breast cancer is a predictive marker of the response to anthracycline-based neoadjuvant chemotherapy

This study aimed at evaluating the usefulness of topoisomerase II alpha (TOP2A) for predicting the effect of anthracycline-based neoadjuvant chemotherapy in breast cancer. The TOP2A status was examined using fluorescent in situ hybridization (FISH) in 14 pre-chemotherapeutic breast cancer tissues, and was also assessed by immunohistochemistry (IHC) in 14 pairs of pre- and post-chemotherapeutic breast cancer specimens. TOP2A gene aberration by IHC tended to show a correlation with pathological responses but this was not statistically significant (p=0.060). On the other hand, the low TOP2A/CEP17 ratio correlated with good pathological responses (p=0.012). TOP2A overexpression was not significantly associated with response (p=0.580). Our results thus suggest that the TOP2A/CEP17 ratio may be a useful predictor of the effects of anthracycline-based neoadjuvant chemotherapy in breast cancer.     

Short-term potentiation at the parallel fiber-Purkinje cell synapse

Changes in synaptic efficacy at the parallel fiber (PF)-Purkinje cell (PC) synapse are postulated to be a cellular basis for motor learning. Although long-term efficacy changes lasting more than an hour at this synapse, i.e., long-term potentiation and depression, have been extensively studied, relatively short lasting synaptic efficacy changes, namely short-term potentiation (STP) lasting for tens of minutes, have not been discussed to date. Here we report that this synapse shows an apparent STP reliably by a periodic burst pattern of homosynaptic stimulation. This STP is presynaptically expressed, since it accompanies with a reduced paired-pulse facilitation and is resistant to postsynaptic Ca(2+) reduction by BAPTA injection or in P/Q-type Ca channel knockout cerebella. This novel type of synaptic plasticity at the PF-PC synapse would be a clue for understanding the presynaptic mechanisms of plasticity at this synapse.     

Feature of food allergy developed during infancy (2)--acquisition of tolerance against hen's egg, cow's milk, wheat, and soybean up to 3 years old]

BACKGROUND: Once food elimination is introduced, it is important to know for doctors when patients generally develop oral tolerance against eliminated food. To clarify the point, following study was conducted. METHODS: We analyzed 304 patient profiles with food allergy in our division between 1994 and 2001. The diagnosis of oral tolerance was determined by the results of food challenges or the accidental episodes of ingestion. RESULTS: By the age of 3 years old, 78% of food allergy patients with soybean, 63% of those with wheat, 60% of those with cow's milk, 51% of those with egg yolk, and 31% of those with egg white developed oral tolerance, respectively. IgE CAP RAST scores against cow's milk, egg yolk, and egg white in the patients without tolerance were significantly higher than those in the patients with tolerance. CONCLUSION: Patients developed oral tolerance firstly against soybean followed by wheat, cow's milk, egg yolk and egg white during the first 3 years of life. The specific IgE antibody levels against egg and cow's milk are important for the diagnosis of tolerance.     

Effects of intra- and extracellular H+ and Na+ concentrations on Na+-H+ antiport activity in the lacrimal gland acinar cells

Kinetic properties of the Na⁺-H⁺ antiport in the acinar cells of the isolated, superfused mouse lacrimal gland were studied by measuring intracellular pH (pH_i) and Na⁺ activity (aNa_i) with the aid of double-barreled H⁺- and Na⁺-selective microelectrodes, respectively. Bicarbonate-free solutions were used throughout. Under untreated control conditions, pH_i was 7.12±0.01 and aNa_i was 6.7±0.6 mmol/l. The cells were acid-loaded by exposure to an NH ₄ ⁺ solution followed by an Na⁺-free N-methyl-d-glucamine (NMDG⁺) solution. Intracellular Na⁺ and H⁺ concentrations were manipulated by changing the duration of exposure to the above solutions. Subsequent addition of the standard Na⁺ solution rapidly increased pH_i. This Na⁺-induced increase in pH_i was almost completely inhibited by 0.5 mmol/l amiloride and was associated with a rapid, amiloride-sensitive increase in aNa_i. The rate of pH_i recovery induced by the standard Na⁺ solution increased in a saturable manner as pH_i decreased, and was negligible at pH_i 7.2–7.3, indicating an inactivation of the Na⁺-H⁺ antiport. The apparent K _m for intracellular H⁺ concentration was 105 nmol/l (pH 6.98). The rate of acid extrusion from the acid-loaded cells increased proportionally to the increase in extracellular pH. Depletion of aNa_i to less than 1 mmol/l by prolonged exposure to NMDG⁺ solution significantly increased the rate of Na⁺-dependent acid extrusion. The rate of acid extrusion increased as the extracellular Na⁺ concentration increased following Michaelis-Menten kinetics (V _max was 0.55 pH/min and the apparent K _m was 75 mmol/l at pH_i 6.88). The results clearly showed that the Na⁺-H⁺ antiport activity is dependent on the chemical potential gradient of both Na⁺ and H⁺ ions across the basolateral membrane, and that the antiporter is asymmetric with respect to the substrate affinity of the transport site. The data agree with the current model of activation and inactivation of the antiporter by an intracellular site through changes in the intracellular Na⁺ and H⁺ concentrations.     

Antimetastatic effect of defibrinogenation with batroxobin depends on the natural killer activity of host in mice

Summary Using batroxobin, a thrombin-like enzyme found in snake venom, the effects of defibrinogenation on artificial lung metastasis in mice were studied. The role of natural killer (NK) cells in the inhibitory effects of defibrinogenation on metastasis was also investigated. Artificial lung metastasis experiments were performed by inoculating either B16-F10 cells or B16-BL/6 cells, highly metastatic strains of B16 melanoma cells, into C57BL/6 mice via the tail vein. The administration of batroxobin significantly inhibited lung metastasis, as did NK activity augmented by poly (I) · poly (C) administration. When both batroxobin and poly (I) · poly (C) were administered, lung metastasis was more markedly inhibited. When NK activity was suppressed by administration of anti-(asialo GM₁) antibody, lung metastasis was markedly increased. When batroxobin was administered with anti-(asialo GM₁) antibody, no inhibitory effects on lung metastasis, such as those seen with batroxobin alone, were observed. The administration of batroxobin had no effect at all on spleen lymphocyte NK activity. These results indicated that defibrinogenation due to batroxobin inhibits lung metastasis, and these effects depend on NK activity of the host.Abbreviations used NK natural killer - BU batroxobin units - FCS fetal calf serum     

Fast and slow blockades of the inward-rectifier K+ channel by external divalent cations in guinea-pig cardiac myocytes

The present patch-clamp study shows that external Mg²⁺, Ca²⁺ and Sr²⁺ decrease the unit amplitude of inward current through the inward-rectifier K⁺ channel in a concentration-dependent manner. Sr²⁺ produces a voltage-dependent flickering block as well, and the fractional electrical distance between the external orifice and the Sr²⁺ binding site () is 0.73. The decrease of unit amplitude is reversible and voltage independent while it does not increase the noise level on the open-channel current. Unit current decreased by Mg²⁺ or Ca²⁺ has a longer mean open time, which is inversely proportional to the unit amplitude. External Mg²⁺ does not decrease the amplitude of unit outward current. A surface potential shift, measured using voltage-dependent Cs⁺ block (=1.60), failed to explain the current decrease. Therefore, we conclude that (1) the external divalent cations cause an extremely fast channel block, which appears as a decreased amplitude of the unit current on the recording system; (2) the blocking site (fast site) is present near the external orifice of the channel, and it is separate from the blocking site (slow site) to which Cs⁺ and Sr²⁺ bind.     

Restricted expression of transgenic HLA-DRA gene in thymic epithelial cells and its role in acquisition of T cell tolerance to self-superantigens and processed DRα-derived peptide

We have established a set of transgenic mouse lines in which the HLA-DRA gene was expressed in different cell types. In one line (DRα-24), DRαEβ^b molecules were expressed on thymic medullary and cortical epithelial cells and all lineages of bone marrow-derived antigen-presenting cells (APC) except for thymic macrophages. By contrast, expression of the molecules in another line (DRα-30) was found on thymic medullary and cortical epithelial cells but not on bone marrow-derived APC in the thymus and periphery. To evaluate the role of thymic epithelial cells in acquisition of T cell tolerance, comparative analysis of DRα-24 and DRα-30 was performed. In DRα-30, T cells expressing TcR Vβ5 and Vβ11 were eliminated to comparable levels to those in DRα-24, suggesting that expression of the DRαEβ^b molecules on thymic epithelial cells are sufficient for clonal deletion of the self-superantigen-reactive T cells. In addition, CD4⁺ T cells from DRa-30 as well as those from DRα-24 were tolerant to DRα-derived peptide/I-A^b complex expressed on spleen cells from DRα-24 even in the presence of exogenous interleukin-2. These observations suggest that expression of the DRα chain in thymic epithelial cells could induce T cell tolerance directed toward naturally processed DRα-derived peptide bound to I-A^b molecules, probably via clonal deletion of the self-reactive T cells.