The activity of the high-affinity K+ uptake system Kdp sensitizes cells of Escherichia coli to methylglyoxal

Expression of the Kdp system sensitizes cells to methylglyoxal (MG) whether this electrophile is added externally or is synthesized endogenously. The basis of this enhanced sensitivity is the maintenance of a higher cytoplasmic pH (pHi) in cells expressing Kdp. In such cells, MG elicits rapid cytoplasmic acidification via KefB and KefC, but the steady-state pHi attained is still too high to confer protection Lowering pHi further by incubation with acetate increases the sensitivity of cells to MG.     

Apoptosis of neutrophils

Cercarial behavior patterns were examined in 4 species of frog lung flukes (Haematoloechus spp.). Cercariae of Haematoloechus complexus, Haematoloechus medioplexus, Haematoloechus longiplexus, and Haematoloechus varioplexus were exposed to 3 species of experimental arthropods and an inanimate control. The number of cercariae attached to an experimental host at 5 min postexposure was recorded. Haematoloechus longiplexus and H. complexus cercariae attached to experimental hosts at higher rates than cercariae of H. medioplexus and H. varioplexus. Cercariae of H. longiplexus attached to experimental hosts in approximately the same numbers as H. complexus, but H. longiplexus penetrated only damselfly naiads, and only at the base of the zygopteran caudal gills. Cercariae of H. complexus, a second intermediate host generalist, were able to penetrate and enter several arthropod species at the intersegmental membranes. Haematoloechus medioplexus and H. varioplexus are restricted to development in dragonfly naiads and cercariae rarely attached to and never penetrated experimental hosts. These behavioral patterns dictate the range of hosts suitable for metacercarial development of H. complexus, H. longiplexus, H. medioplexus, and H. varioplexus. The evolution of disparate patterns of behavior among the cercariae of these 4 congeners has directly affected subsequent patterns of transmission to the definitive host.     

Head-related transfer functions of the barn owl: measurement and neural responses

Sounds arriving at the eardrum are filtered by the external ear and associated structures in a frequency and direction specific manner. When convolved with the appropriate filters and presented to human listeners through headphones, broadband noises can be precisely localized to the corresponding position outside of the head (reviewed in Blauert, 1997). Such a 'virtual auditory space' can be a potentially powerful tool for neurophysiological and behavioral work in other species as well. We are developing a virtual auditory space for the barn owl, Tyto alba, a highly successful auditory predator that has become a well-established model for hearing research. We recorded catalogues of head-related transfer functions (HRTFs) from the frontal hemisphere of 12 barn owls and compared virtual and free sound fields acoustically and by their evoked neuronal responses. The inner ca. 1 cm of the ear canal was found to contribute little to the directionality of the HRTFs. HRTFs were recorded by inserting probetube microphones to within about 1 or 2 mm of the eardrum. We recorded HRTFs at frequencies between 2 and 11 kHz, which includes the frequencies most useful to the owl for sound localization (3-9 kHz; Konishi, 1973). Spectra of virtual sounds were within +/- 1 dB of amplitude and +/- 10 degrees of phase of the spectra of free field sounds measured near to the eardrum. The spatial pattern of responses obtained from neurons in the inferior colliculus were almost indistinguishable in response to virtual and to free field stimulation.     

A chemoenzymatic synthesis of UDP-(2-deoxy-2-fluoro)-galactose and evaluation of its interaction with galactosyltransferase

The left internal mammary artery-to-the left pulmonary artery shunt was created in a 16-year-old boy with single ventricle, severe pulmonary stenosis palliated by Glenn shunt at the age of two. Four years follow-up angiogram demonstrated a significant increase of the diameter of the left internal mammary artery from 4 to 7 mm. The internal mammary artery is a good alternative conduit for a systemic-to-pulmonary artery shunt for a cyanotic heart disease because of its growth potential.     

Agreement between face-to-face and telephone-administered mood ratings in patients with rapid cycling bipolar disorder

BACKGROUND AND PURPOSE: Clinical trials have demonstrated that high dose radiation therapy and daily cisplatin (CDDP) could increase local control and survival in carcinoma from various sites. The present phase I-II study has combined high dose radiation therapy and daily CDDP at escalating dosages. METHODS: From August 1994 to December 1995, 23 patients with non-resectable carcinoma of the pancreas were enrolled in a phase I-II multicentric, pilot study to test the toxicity and the effectiveness of high dose radiotherapy and daily cisplatin (CDDP) at escalating dosages. A dose of 6 mg/sqm/day of CDDP was selected for the phase II step since no grade IV toxicity occurred in any patient in the phase I step. RESULTS: Toxicity was considered fairly acceptable. At the time of analysis, the 23 patients who entered the study had clear evidence of evolutive disease either locally or distantly in the liver. It is suggested that high dose radiotherapy (60 Gy continuously) and daily CDDP have little effect on local control of the tumor and survival, and only a moderate effect on pain. CONCLUSIONS: In unresectable, apparently non-metastatic cancers of the pancreas, there is an urgent need for new agents or new combinations of agents to be tested.     

Apolipoprotein B gene polymorphisms in Taiwanese ischemic stroke patients

We analyzed the AluI restriction fragment length polymorphism (RFLP) of the apolipoprotein B (apoB) gene to determine the association between AluI allelic distribution and the occurrence of ischemic stroke in Taiwan. A total of 44 healthy volunteers and 159 ischemic stroke patients were included in the study. The allele frequency of AluI was very similar in the two groups, 0.87 in the patient group and 0.89 in the control group, for the major allele A-. The distribution of A-/A-, A-/A+, and A+/A+ genotypes of the patients was not significantly different from that of the controls. Among ischemic stroke patients, the A+ allele of the AluI restriction site was significantly associated with elevated apoB levels. The results of this study suggest that the presence of the rare AluI RFLP may contribute to an elevated plasma apoB level, which is a known risk factor for ischemic stroke.     

Redox potentials for yeast, Escherichia coli and human glutathione reductase relative to the NAD+/NADH redox couple: enzyme forms active in catalysis

The flavoenzyme glutathione reductase catalyzes the NADPH-dependent reduction of glutathione disulfide, yielding two molecules of glutathione. The oxidation-reduction potentials, Eox/EH2 (two-electron reduced enzyme), for yeast, Escherichia coli, and human glutathione reductase have been determined between pH 6.0 and 9.8 relative to the nonphysiological substrate couple NAD+/NADH and were found to be -237, -243, and -227 mV (+/-5 mV) at pH 7.0 and 20 degreesC, respectively. The potential as a function of pH demonstrated slopes of -51, -45, and -42 mV/pH unit, respectively, at low pH and -37, -31, and -34 mV/pH unit, respectively, at high pH. The change in slope indicated pKa values of 7.4, 8.5, and 7.6, respectively. The slopes indicate that two protons are associated with the two-electron reduction of Eox at low pH and that only one proton is involved with the two-electron reduction of Eox at high pH, provided that the effects of nearby titratable residues are considered in the data analysis. The influence of four such groups, Cys50, Cys45, His456', and either Tyr107 or the flavin-(N3), has been included (residue numbering refers to the yeast sequence). The enzyme loses activity upon deprotonation of the acid-base catalyst at high pH. Since the pKa ascribed to the EH2-to-EH- ionization is lower than the pKa of the acid-base catalyst, both the EH2 and EH- forms of glutathione reductase must be catalytically active, in contrast to the closely related enzyme lipoamide dehydrogenase, for which only EH2 is active.