From vasopressin receptor to water channel: intracellular traffic, constraint and by-pass

To test a potential "gating" effect of noradrenaline (NA) in the auditory cortex, the acoustic threshold was estimated by determining the rate-level function of neurons before, during, and after microiontophoretic application (5-40 nA) of NA. The rationale behind this experiment was that a gating effect should decrease the threshold for acoustic excitatory responses. From 84 recorded neurons, we observed (1) that application of NA increased the threshold for 48 of 84 cells, and (2) that, on average, the slope of the rate-level functions was unchanged. These effects on the threshold are consistent with the fact that the dominant effect of NA on the evoked response is inhibition for 34 of 84 cells; increases in evoked responses were observed for only 14 of 84 cells. GABA application (0-50 nA) also led to increased response threshold for 19 of 24 cells (unaffected, 5 of 24 cells). However, for three cells the effect of GABA application was antagonized by bicuculline application, while on the same cells bicuculline application did not prevent the noradrenergic increase in threshold. The effect induced by NA on the threshold raises questions about the generality of a gating effect of NA in sensory neocortex.     

Surgical management of total anomalous pulmonary venous drainage: impact of coexisting cardiac anomalies

BACKGROUND: Recent reports have cited improving results for surgical management of isolated total anomalous pulmonary venous drainage. Complex cases (with other cardiac anomalies) are less frequently reported and are associated with higher mortality. METHODS: Retrospective review identified 170 consecutive patients treated for total anomalous pulmonary venous drainage from 1982 to 1996: 44 cases were "complex" (with significant associated cardiac lesions) and 126 cases were "simple." RESULTS: Operative mortality for simple cases decreased from 26% to 8%, and mortality for complex cases remained constant at 52%. Age, size, and the presence of atrial isomerism were univariate predictors of mortality. Multivariable analysis identified only univentricular hearts and associated cardiac lesions as predictors of operative mortality. Pulmonary artery (n = 16) and arteriopulmonary (n = 7) shunting strategies for complex cases resulted in less than 30% long-term survival. CONCLUSIONS: Despite improvement in survival for simple cases, management of total anomalous pulmonary venous drainage with single-ventricle hearts or other associated cardiac lesions remains problematic.     

Isolation and characterization of a monoclonal anti-quadruplex DNA antibody from autoimmune "viable motheaten" mice

A cell line that produces an autoantibody specific for DNA quadruplex structures has been isolated and cloned from a hybridoma library derived from 3-month-old nonimmunized autoimmune, immunodeficient "viable motheaten" mice. This antibody has been tested extensively in vitro and found to bind specifically to DNA quadruplex structures formed by two biologically relevant sequence motifs. Scatchard and nonlinear regression analyses using both one- and two-site models were used to derive association constants for the antibody-DNA binding reactions. In both cases, quadruplexes had higher association constants than triplex and duplex molecules. The anti-quadruplex antibody binds to the quadruplex formed by the promoter-region-derived oligonucleotide d(CGCG4GCG) (Ka = 3.3 x 10(6) M-1), and has enhanced affinity for telomere-derived quadruplexes formed by the oligonucleotides d(TG4) and d(T2G4T2G4T2G4T2G4) (Ka = 5.38 x 10(6) and 1.66 x 10(7) M-1, respectively). The antibody binds both types of quadruplexes but has preferential affinity for the parallel four-stranded structure. In vitro radioimmunofilter binding experiments demonstrated that purified anti-DNA quadruplex antibodies from anti-quadruplex antibody-producing tissue culture supernatants have at least 10-fold higher affinity for quadruplexes than for triplex and duplex DNA structures of similar base composition and length. The antibody binds intramolecular DNA triplexes formed by d(G4T3G4T3C4) and d(C4T3G4T3G4), and the duplex d(CGCGCGCGCG)2 with an affinities of 6. 76 x 10(5), 5.59 x 10(5), and 8.26 x 10(5) M-1, respectively. Competition experiments showed that melted quadruplexes are not effective competitors for antibody binding when compared to native structures, confirming that the quadruplex is bound structure-specifically. To our knowledge, this is the first immunological reagent known to specifically recognize quadruplex structures. Subsequent sequence analysis demonstrates homologies between the antibody complementarity determining regions and sequences from Myb family telomere binding proteins, which are hypothesized to control cell aging via telomeric DNA interactions. The presence of this antibody in the autoimmune repertoire suggests a possible linkage between autoimmunity, telomeric DNA binding proteins, and aging.     

Further studies on the influence of genotype and dietary protein on the performance of broilers

An experiment was conducted to quantify genetic differences in response to dietary protein level of male vs female broilers. Broilers (1 d old) from a "high-yield" strain cross (Ross x Ross 208) and a "fast-growing" strain cross (Peterson x Arbor Acres) were placed on fresh pine shavings in floor pens. From Day 0 to 18, all birds were fed a 23% CP starter diet. During Days 18 to 53 male birds were fed either a 16, 18, 20, 22, 24, or 26% CP diet (3,200 kcal ME/kg) and female birds were fed the 16, 20, or 24% CP diet. Significant differences (P < 0.05) were noted in the performance of the different strains. Ross x Ross 208 male birds had a higher body weight (3.37 vs 3.16 kg), higher feed intake (7.08 vs 6.78 kg), higher breast yield (31.76 vs 29.25%), higher carcass yield (73.90 vs 71.85%), and a lower adjusted feed conversion ratio (FCR; 2.10 vs 2.16 g:g) than Peterson x Arbor Acres males at 53 d of age. As compared to Peterson x Arbor Acres females, Ross x Ross 208 female broilers also had a higher body weight (2.68 vs 2.55 kg), higher breast meat yield (33.61 vs 30.80%), higher carcass yield (75.31 vs 73.91%), and lower adjusted FCR (1.97 vs 2.04 g:g). Qualitative differences in the response of these strains were confirmed and better qualitative data is presented that can be used to predict the important output parameters from the import inputs in broiler production.     

Synthesis and glutathione S-transferase structure-affinity relationships of nonpeptide and peptidase-stable glutathione analogues

A series of nonpeptidic glutathione analogues where the peptide bonds were replaced by simple carbon-carbon bonds or isosteric E double bonds were prepared. The optimal length for the two alkyl chains on either side of the mercaptomethyl group was evaluated using structure-affinity relationships. Affinities of the analogues 14a-f, 23, and 25 were evaluated for a recombinant GST enzyme using a new affinity chromatography method previously developed in our laboratory. Analysis of these analogues gives an additional understanding for GST affinity requirements: (a) the carbon skeleton must conserve that of glutathione since analogue 14a showed the best affinity (IC50 = 5.2 microM); (b) the GST G site is not able to accommodate a chain length elongation of one methylene group (no affinity for analogues 14c,f); (c) a one-methylene group chain length reduction is tolerated, much more for the "Glu side" (14d, IC50 = 10.1 microM) than for the "Gly side" (14b, IC50 = 1800 microM); (d) the mercaptomethyl group must remain at position 5 as shown from the null affinity of the 6-mercaptomethyl analogue 14e; (e) the additional peptide isosteric E double bond (25) or hydroxyl derivative (23) in 14e did not help to retrieve affinity. This work reveals useful information for the design of new selective nonpeptidic and peptidase-stable glutathione analogues.     

Homology and functional similarity of an hrp-linked pathogenicity locus, dspEF, of Erwinia amylovora and the avirulence locus avrE of Pseudomonas syringae pathovar tomato

The "disease-specific" (dsp) region next to the hrp gene cluster of Erwinia amylovora is required for pathogenicity but not for elicitation of the hypersensitive reaction. A 6.6-kb apparent operon, dspEF, was found responsible for this phenotype. The operon contains genes dspE and dspF and is positively regulated by hrpL. A BLAST search revealed similarity in the dspE gene to a partial sequence of the avrE locus of Pseudomonas syringae pathovar tomato. The entire avrE locus was sequenced. Homologs of dspE and dspF were found in juxtaposed operons and were designated avrE and avrF. Introduced on a plasmid, the dspEF locus rendered P. syringae pv. glycinea race 4 avirulent on soybean. An E. amylovora dspE mutant, however, elicited a hypersensitive reaction in soybean. The avrE locus in trans restored pathogenicity to dspE strains of E. amylovora, although restored strains were low in virulence. DspE and AvrE are large (198 kDa and 195 kDa) and hydrophilic. DspF and AvrF are small (16 kDa and 14 kDa) and acidic with predicted amphipathic alpha helices in their C termini; they resemble chaperones for virulence factors secreted by type III secretion systems of animal pathogens.     

Pain threshold values during periodontal probing: assessment of maxillary incisor and molar sites

Probing pain threshold (PPT) assessments were conducted in the facial and oral sulci of maxillary central incisors and first molars of 10 periodontally healthy adults. All subjects were systemically healthy, free of pain, and reported no current medication usage. A computer-linked electronic probe, modified to deliver steadily increasing forces up to 200 grams, was used to collect the data. The system contained a subject operated "off-switch" which, upon activation, signaled the computer to record the subject's PPT. Assessments of each subject's PPTs were conducted on 3 separate occasions at 7-day intervals. Results indicated that the facial sulci of the incisors were the most pain sensitive. They displayed a mean PPT of 50.9 +/- 26.6 grams. The oral sulci of the incisors exhibited a mean PPT of 76.5 +/- 45.2 grams. Facial and oral sulci of the molars evidenced mean PPT values of 102.6 +/- 52.1 grams and 113.5 +/- 51.3 grams, respectively. These data suggest that sulci associated with incisor teeth are nearly twice as pain sensitive as sulci associated with molar teeth. In addition, facial sulci are significantly more pain sensitive than oral sulci. Data did not indicate a visit effect nor a side-of-mouth effect on PPT values.     

Oncocytic cancers of the thyroid. Hürthle cell cancers

Nonvalvular atrial fibrillation is a frequent finding in elderly patients; the risk of thromboembolic complications is comparable to that reported in patients with rheumatic atrial fibrillation. Recently, 6 multicenter clinical trials (5 primary prevention, 1 secondary prevention trail) have been published which demonstrate equivocally that oral anticoagulation therapy significantly reduces the embolic risk in patients with nonvalvular atrial fibrillation by about 67% to 87%. The target INR of anticoagulation with warfarin in 2 of these trials was 1.4 to 2.8 ("low-dose" warfarin); interestingly, the magnitude of risk reduction was similar to these 2 studies with "low-dose" warfarin as it has been reported by the others using full-dose warfarin with an INR target between 2.0 and 4.5. Side effects of oral anticoagulation (severe bleeding complications) were low in these trials. Thus, the benefit-risk ratio in these 6 clinical trials encourage the use of oral anticoagulation in patients with nonvalvular atrial fibrillation. It will be a challenge to transfer these results to clinical practice, and to define in more detail the risk-benefit ratios for subgroups of patients with atrial fibrillation, e.g. patients > 75 years of age, or patients with "lone" or paroxysmal atrial fibrillation. It is well established that patients with chronic atrial fibrillation undergoing medical or DC-cardioversion are at risk for thromboembolic complications. In previous studies, this risk appears to be in the range of 2% without concomitant anticoagulation, but only 0.33% in those patients with concomitant anticoagulation. Thus, it is widely accepted that patients should be anticoagulated for at least 2 weeks prior and after planned cardioversion. Recently, an alternative concept has been proposed omitting anticoagulation before cardioversion; instead, transesophageal echocardiography is used to exclude intracardiac thrombi. Because it is known that mechanical function of the left atrium and appendage is still impaired after cardioversion, this concept of echocardiographic-guided cardioversion does not assign the necessity of anticoagulation at the day of cardioversion, and 2 weeks afterwards. The safety aspects of this concept of echocardiographic-guided cardioversion is under current investigation.     

Rerouting of the intratemporal facial nerve: an analysis of the literature

Anterior rerouting of the intratemporal facial nerve in the infratemporal fossa approach is employed to access to the jugular bulb, hypotympanum, and lateral skull base, whereas posterior rerouting of the facial nerve, as employed in the transcochlear craniotomy, is most frequently used for surgery of the posterior fossa, cerebellopontine angle, prepontine region, and petrous apex. Facial nerve rerouting may lead to facial paresis or paralysis. This review of the literature is intended to define the physiologic "cost" of these procedures, so that the neurotologic surgeon can determine if the morbidity incurred in these techniques is worth the resultant exposure. Inconsistencies in reporting facial function places into question the validity of some of the cumulative data reported. Postoperatively, grades I-II facial nerve function was seen in 91% of patients undergoing short anterior rerouting, 74% of patients undergoing long anterior rerouting, and 26% of patients undergoing posterior complete rerouting. Although facial nerve rerouting allows unhindered exposure to previously inaccessible regions, it is achieved at the cost of facial nerve function. Facial nerve dysfunction increases with the length of facial nerve rerouted.