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PubMed1990

Synthesis, purification and initial structural characterization of octarellin, a de novo polypeptide modelled on the alpha/beta-barrel proteins.

We have attempted to construct an artificial polypeptide that folds like the eight-stranded parallel beta-barrel structures. Our approach consists of repeating eight times a unit peptide designed to adopt a 'beta-strand/alpha-helix' pattern. A first 'test' sequence for this structural unit was deduced from a series of parameters defined after an analysis of three natural alpha/beta-barrel proteins and including principally the lengths of the secondary structure elements, the alpha/beta packing and the fitting on average Garnier profiles. The gene encoding this structural unit was synthesized, cloned and expressed in Escherichia coli either as a monomer or as direct repeats of 2-12 units. Preliminary structural characterization of the 7-, 8- and 9-fold unit polypeptides by circular dichroism measurements indicates the presence of the predicted amount of alpha-helix in the three proteins. Further analysis by urea-gradient gel electrophoresis demonstrates that, in the conditions tested, only the 8-fold unit polypeptide forms a compact structure through a cooperative and rapid two-state folding transition involving long-range molecular interactions.

Amino Acid Sequence↗

PubMed1982

Alcohol drinking induced in the monkey by tetrahydropapaveroline (THP) infused into the cerebral ventricle.

In the female macaque monkey acclimated to a primate chair, Collison cannulae were stereotaxically implanted bilaterally in the lateral cerebral ventricle. The voluntary self-selection of ethyl alcohol versus water was determined repeatedly during a series of 12-day test sequences in which the concentration of the alcohol solution offered to the primate was increased systematically over 12 successive days from 3% to 30%. Following control preference sequences, the dopamine-dopaldehyde condensation product, tetrahydropapaveroline (THP), was infused daily in each monkey's cerebral ventricle (ICV) in a volume of 200-400 microliter. THP was dissolved in an artificial CSF, with pH adjusted to 3.8 with 0.1 mg/ml ascorbate, and infused in one of ten doses varying from 0.125-400 microgram. EAch monkey was administered one low and one high dose of the condensation product throughout each of two successive alcohol preference tests. When THP was infused in doses of less than 2.0 microgram, the monkeys' alcohol preference failed to change. However, a marked increase in alcohol intake, in terms of both g/kg/day as well as the proportion of alcohol to water selected, was produced by THP infused ICV in doses of 5.0 to 20.0 microgram. Although average intakes in the latter animals were between 4.0 and 5.0 g/kg/day, the monkeys selected certain concentrations of alcohol in amounts of up to 7.0 g/kg/day. The two highest doses of THP, 40.0 and 400.0 microgram, inhibited the self-selection of alcohol even when presented in low, non-aversive concentrations in the 3% to 6% range. Overall, these results with the primate corroborate earlier findings in the rat of abnormal alcohol intake produced by centrally infused THP. They further support the theory that amine-aldehyde metabolites, if present in certain concentrations in the brain, may constitute a causal neurochemical factor in the addictive or otherwise immoderate drinking of alcohol.

Alcohol Drinking↗

PubMed1991

Single-unit recording in the ventral cochlear nucleus of behaving cats.

A method is described for single-unit recording in the ventral cochlear nucleus (VCN) of behaving cats. Five cats were implanted with titanium head-restraint devices and acetal plastic recording chambers. The recording chamber directed microelectrodes through the cerebellum and into the VCN. Electrophysiological recordings were obtained from isolated VCN units while the cats engaged in an auditory discrimination task. The task required the cats to discriminate changes in the temporal pattern of a series of tone or noise bursts. Cats initiated the testing sequence by depressing a lever, and obtained food by releasing the lever when the pattern of stimuli changed from one 200-ms burst/s to four 50-ms bursts/s. Stimulus features (i.e., frequency, level, duration) were manipulated to characterize the physiological responses of VCN units. Preliminary data suggest that peri-stimulus time histograms (PSTHs) and rate-level functions (RALVs) obtained from behaving cats are similar to those previously described in anesthetized and decerebrate cats when units are tested with tones in quiet backgrounds. However, in comparison to anesthetized and decerebrate cats, units obtained in behaving cats demonstrate a more sensitive rate representation of stimulus level when tested in continuous background noise.

Acoustic Stimulation↗

PubMed1977

Effect of histamine and methacholine on nasal airway resistance in atopic and nonatopic subjects. Comparison with bronchial challenge and skin test responses.

Serial nasal, intracutaneous, or bronchial challenges were carried out with solutions containing 2- or 3-fold increments in histamine (H) or methacholine (Meth) concentration until nasal airway resistance (NAR) increased by more than 100%, a large intracutaneous reaction was elicited, or FEV1 decreased by 20% or more. Thirty nonatopic and 48 asymptomatic atopic subjects were studied, the latter group divided into rhinitic patients with and without asthma. Several types of data analysis demonstrated there was no significant difference in the nasal or cutaneous effects of H or Meth between the atopic and nonatopic groups. Comparable results were obtained in a subgroup of 39 subjects (13 normal, 13 atopic, and 13 atopic with asthma) who underwent all six test sequences (i.e., nasal, cutaneous, and bronchial with both drugs). As expected, the asthmatics showed significantly increased bronchial reactivity to both agents. In comparison with Meth, H had a much greater effect on the nasal mucosa and skin than on the bronchi. It is concluded that, contrary to bronchial responses, but in accord with cutaneous reactivity, the nasal responses of nonatopic subjects, atopic persons with allergic rhinitis alone, and subjects with both allergic rhinitis and asthma show no intergroup differences on testing with H or Meth.

Airway Resistance↗

PubMed1976

Elastic behavior of brain tissue in vivo.

A measurement system and a test sequence have been developed to determine the in vivo elastic response of brain tissue in terms of a pressure-depth ratio. This parameter appears sensitive to changes in the tissue environment that may occur due to the influence of, e.g., anesthetic agents, hyperventilation, etc., and thus may be useful in evaluating such influences. The measurements are made with the dura-arachnoid membranes intact, thus maintaining the influence of the cerebrospinal fluid compartment on the response behavior of the brain tissue that comprises the subpial region. As an integral part of the test, the procedure also serves to determine the depth or position of the subpial region and thus assures that the subsequent pressure-depth measurements invole brain tissue response. Finally, some discussion is given to relating the measured pressure-depth ratio to the classical elastic modulus. Values of the pressure-depth ratio and the corresponding elastic modulus for seven dogs are given.

Animals↗

PubMed2025

Cell-free DNA aneuploidy score as a dynamic early response marker in prostate cancer.

Cell-free circulating tumor DNA (ctDNA) has emerged as a promising biomarker for response evaluation in metastatic castration-resistant prostate cancer (mCRPC). The current study evaluated the modified fast aneuploidy screening test-sequencing system (mFast-SeqS), a quick, tumor-agnostic and affordable ctDNA assay that requires a small input of DNA, to generate a genome-wide aneuploidy (GWA) score in mCRPC patients, and correlated this to matched metastatic tumor biopsies. In this prospective multicenter study, GWA scores were evaluated from blood samples of 196 mCRPC patients prior to treatment (baseline) with taxanes (docetaxel and cabazitaxel) and androgen receptor signaling inhibitors (ARSI; abiraterone and enzalutamide), and from 74 mCRPC patients at an early timepoint during treatment (early timepoint; median 21 days). Z-scores per chromosome arm were tested for their association with tumor tissue genomic alterations. We found that a high tumor load in blood (GWAhigh) at baseline was associated with poor response to ARSI [HR: 2.63 (95% CI: 1.86-3.72) P < 0.001] but not to taxanes. Interestingly, GWAhigh score at the early timepoint was associated with poor response to both ARSIs [HR: 6.73 (95% CI: 2.60-17.42) P < 0.001] and taxanes [2.79 (95% CI: 1.34-5.78) P = 0.006]. A significant interaction in Cox proportional hazards analyses was seen when combining GWA status and type of treatment (at baseline P = 0.008; early timepoint P = 0.018). In summary, detection of ctDNA in blood by mFast-SeqS is cheap, fast and feasible, and could be used at different timepoints as a potential predictor for outcome to ARSI and taxane treatment in mCRPC.

Humans↗

PubMed1983

Characterization of the chicken vimentin gene: single copy gene producing multiple mRNAs.

Genomic clones and cDNA plasmids were isolated for the intermediate filament protein vimentin from chicken. The identity of the various clones was determined both by mRNA selection [Paterson, B. M. & Roberts, B. E. (1981) in Gene Amplification and Analysis, Structural Analysis or Nucleic Acids, eds. Chirikjian, J. G. & Papas, T. S. (Elsevier, North Holland), Vol. 2, pp. 418-435] and nucleotide sequence analysis. Restriction analysis, hybridization data, and heteroduplex studies confirmed that all of the genomic isolates contained overlapping fragments of an identical vimentin gene. No evidence for the existence of a second vimentin gene could be found by a Southern analysis either by using coding fragments from the purified vimentin gene or by using cDNA plasmids as probe. Likewise, copy-number experiments verified that the vimentin gene was present only once in the haploid chicken genome. However, in a RNA blot analysis, at least two equally abundant vimentin mRNA species of approximately 2,200 and 2,500 nucleotides in length were detected in all RNAs tested. Sequence analysis revealed that the vimentin gene contained two sets of tandem polyadenylylation sites, 249 and 532 nucleotides downstream from the stop codon for protein synthesis. It is proposed that the larger mRNA species arise because of complete transcription of the 3'-end of the vimentin gene (560 nucleotides of 3' nontranslated sequence), whereas the smaller mRNA species terminate after the first set of polyadenylylation sites.

Animals↗

PubMed1986

Use of the Mega Code to evaluate team leader performance during advanced cardiac life support.

The Mega Code is a simulated cardiac arrest during which students practice as members of a team and learn to integrate the knowledge and skills of advanced cardiac life support (ACLS). This study used the Mega Code and American Heart Association (AHA) standards to evaluate 32 medical residents (MDs) and nine critical care nurses (RNs) in the role of ACLS team leader. All had been previously trained in ACLS. The testing sequence included ventricular fibrillation (VF) refractory to initial countershock (defib), asystole after second defib, recurrent VF after drug therapy, and finally sinus rhythm after third defib. A blood gas report indicated respiratory acidosis and hypoxemia. Assessment of patient status was poor in both groups, although MDs did significantly (p = .001) better than RNs. Other problem areas were drug therapy and trouble-shooting are not adequately stressed in the AHA ACLS curriculum; moreover, there is no lecture that specifically addresses the team approach to resuscitation and the role of team leader. We found that the Mega Code effectively evaluated individual and group performance. Results of objective-based Mega Code testing can be used both to improve ACLS curriculum and to indicate areas to be stressed during refresher training.

Cardiology↗

PubMed1989

Clinical implications of resilient denture lining material research. Part I: Flexibility and elasticity.

The clinical use of resilient denture liners is based on their flexibility and elasticity. The nine commercial resilient denture liners measured were less flexible during and after simulated chewing and clenching test sequences. The elasticity of the intraoral-cure liners reached maximal values at 24 hours. Although interpretations require caution, the results imply that the dentist should (1) use maximum liner thickness in the denture base when conditioning abused supporting tissues because of the material's tendency to stiffen under function, and (2) leave a functional impression in the mouth for at least 24 hours before pouring the cast.

Chemical Phenomena↗

PubMedDate not supplied

Instrumented evaluation of knee laxity: a comparison of five arthrometers.

We performed a prospective study on 50 subjects with normal knees and 50 patients with chronic unilateral disruption of the anterior cruciate ligament. In a randomized testing sequence, both groups were examined with five arthrometers: the MEDmetric KT-1000, the Stryker Knee Laxity Tester, the Acufex Knee Signature System, the Dyonics Dynamic Cruciate Tester, and the Genucom Knee Analysis System. Each examination was performed according to protocol with the knee at 30 degrees of flexion. The total anterior laxity measurements of the normal subjects using the Dyonics Dynamic Cruciate Tester and Acufex Knee Signature System were approximately half of the KT-1000, Stryker, and Genucom values. A comparison of the side-to-side measurements revealed no statistically significant difference in the values of the five arthrometers. However, the Genucom showed an unacceptably high number of normal subjects with laxity values that suggested an anterior cruciate ligament tear. Total anterior laxity measurements of the anterior cruciate ligament deficient knees were almost twice those of normal knees with each device except the Genucom. Comparison of the mean side-to-side difference in the patients with ACL deficiency demonstrated statistically significant differences in the values recorded with the five arthrometers. The side-to-side difference was greatest with the KT-1000 and least for the KSS. In the 89 N Lachman test, the KT-1000 and Stryker demonstrated the highest diagnostic accuracy. The maximum manual test improved the accuracy of each device. This study establishes the total anterior laxity measurements cannot be generalized from one device to another in either group of subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1988

Binding of 9-aminoacridine to bulged-base DNA oligomers from a frame-shift hot spot.

Complexes of 9-aminoacridine and two derivatives with oligomers based on the sequence of a hot spot for frame-shift mutations, 5'dGATGGGGCAG, are investigated by proton NMR and equilibrium dialysis. Competition dialysis experiments show that the drug binds bulge-containing oligomers more strongly than regular duplexes of similar sequence and length, with one apparent strong site. A duplex containing an extra cytidine in a run of C's has the highest affinity for 9-aminoacridine among the sequences tested. An oligomer containing five consecutive G.C pairs shows cooperative drug binding, indicating that G tracts of this length may have an altered helical structure. Complexes of a regular 8-mer and a 9-mer containing a bulged guanosine are examined in detail by two-dimensional NMR techniques. 9-Aminoacridine preferentially binds at TpG sites in the 8-mer but binds primarily at the bulged guanosine in the G-bulge 9-mer. Drug-DNA NOE's in the 8-mer complex are compared with the crystal structure of 9-aminoacridine and 5-iodo-CpG [Sakore et al. (1979) J. Mol. Biol. 135, 763-785]. The NMR data suggest that the drug intercalates across the base pairs of both strands with the amino group projecting into the minor groove.

Aminacrine↗

PubMed1992

Effect of head orientation on the diagnostic sensitivity of posturography in patients with compensated unilateral lesions.

Patients with compensated unilateral vestibular lesions often have no detectable abnormality on conventional posturography. The purpose of this study was to determine whether a change in head orientation could improve the diagnostic sensitivity of the test for these patients. Twenty-four patients with known unilateral vestibulopathy and twenty-four normal controls were tested on the EquiTest apparatus in four head positions: head centered, head tilted right, head tilted left, and head extended. The sensory organization test was performed for each head position, using a single trial for each sensory condition. The test sequence was randomized to account for simple order effects. The subject's equilibrium was quantified by a performance index and a composite score of all sensory conditions was calculated for each head position. Patients with unilateral vestibulopathy had more postural sway with the head tilted contralateral to the side of lesion. The difference between the mean composite scores for ipsilateral and contralateral head tilts was statistically significant (p less than 0.05). When individual trials were compared, equilibrium scores were significantly different only for sensory conditions that required vestibular input. Head extension increased postural sway in both patients and controls. Equilibrium scores were significantly different for all sensory conditions in which the support was sway-referenced. We suggest that the results of head extension in patients are similar to those found in normal individuals.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1988

The diagnosis of polyarteritis nodosa. II. Empirical verification of a decision analysis model.

We evaluated our literature-based estimates of diagnostic test characteristics and aggressive and conservative strategies for the diagnosis of polyarteritis nodosa (PAN) by reviewing 1980 through 1985 data from the University of Chicago Medical Center, Michael Reese Hospital, and Northwestern University Medical School. Test specificity was calculated by reviewing pathology and radiology reports on all relevant procedures done at the University of Chicago Medical Center in 1984 and 1985. There were no reports of false-positive findings (including angiography); thus, test specificity was 100% for muscle, nerve, kidney, liver, and testicular biopsy, which was comparable with our literature-based estimate of 97%. Test sensitivity was based on the 18 confirmed cases of PAN from the 3 institutions and was similar to that in published reports, ranging from 0% for liver biopsy to 100% for visceral angiography. Review of each case for diagnostic test sequence showed an average of 2 diagnostic procedures to confirm the diagnosis (range 1-6). Eight of 18 patients were evaluated according to the conservative strategy we proposed from our literature-based decision analysis approach. No patient was evaluated with the aggressive strategy, although 1 patient had 6 invasive procedures. Of the remaining 10 patients, 9 represented cases that might have been confirmed had the conservative approach been used, and if it had been used, 6 patients would have had the diagnosis confirmed. Thus, the minimum sensitivity of our conservative strategy is 78%, although based on these data, it could be as high as 100%.(ABSTRACT TRUNCATED AT 250 WORDS)

Evaluation Studies as Topic↗

PubMed1990

Identification of Brassica oleracea monosomic alien chromosome addition lines with molecular markers reveals extensive gene duplication.

Chromosomes of Brassica oleracea (2n = 18) were dissected from the resynthesized amphidiploid B. napus Hakuran by repeated backcrosses to B. campestris (2n = 20), creating a series of monosomic alien chromosome addition line plants (2n = 21). Using morphological, isozyme and restriction fragment length polymorphism markers (RFLPs), 81 putative loci were identified. Of nine possible synteny groups, seven were represented in the 25 monosomic addition plants tested. Sequences homologous to 26% of the 61 DNA clones utilized (80% were cDNA clones) were found on more than one synteny group, indicating a high level of gene duplication. Anomalous synteny associations were detected in four 2n = 21 plants. One of these plants showed two markers from one B. oleracea chromosome associated with a second complete B. oleracea synteny group, suggesting translocation or recombination between non-homologous chromosomes in Hakuran or the backcross derivatives. The other three 2n = 21 plants each contained two or more B. oleracea synteny groups, suggesting chromosome substitution.

Brassica↗

PubMed1992

Mapping and characterization of 129 cosmids on human chromosome 11p.

We constructed cosmid libraries from human-hamster somatic cell hybrids that possess all or part of the short arm of chromosome 11 as their only human complement and isolated 129 human 11p clones. These cosmids map to 22 of 25 intervals distinguished by a hybrid panel for chromosome 11p. Forty-eight single-copy sequences were subcloned from 25 cosmids. Six of 17 (35%) single-copy sequences tested identify 11 new polymorphisms. Restriction endonuclease analysis identified CpG islands in 16 of 68 cosmids (23.5%). Analysis of the distribution of restriction endonuclease sites recognizing CpG dinucleotides showed that clusters of these sites, including those associated with the 5' region of an 11p13 Wilms' tumor gene, WT1, can span greater distances than generally recognized. The cosmids reported here should contribute to the construction of long-range physical maps and the isolation of additional genes on the short arm of chromosome 11.

Blotting, Southern↗

PubMed1986

Postextrasystolic potentiation: analysis of methods of induction.

Studies were conducted in 15 patients with coronary artery disease to determine if the type of pacing used to induce an extrasystole had a bearing on subsequent postextrasystolic potentiation (PESP) and if the fact that these were evaluated in jeopardized or nonjeopardized portions of the ventricle altered the ability to assess PESP. Two types of pacing were used. In the first group, all beats in the test sequence (basic heart rate, extrasystole, and postextrasystole) were delivered from a programmed external pacemaker. This group was termed the "all-paced" (AP) group, and the postextrasystole was introduced before a compensatory pause could occur, so that loading conditions within the ventricle at the last regular beat and after the extrasystole were not different. In the second group, the extrasystole was coupled to the sensed intrinsic heart rate of the patient, and the postextrasystole was allowed to occur spontaneously. This group was termed the "sensed-paced" (SP) group. Despite differences in basic heart rates and postextrasystolic intervals between the two groups, comparable results were obtained with the two techniques. However, the postextrasystole in the SP group occurred much earlier than expected, probably due to intrinsic cardioacceleration during ventriculography. The net result was that loading conditions in this group before and after the extrasystole were also not different from each other. Results from the pacing techniques were not influenced by whether they were obtained from jeopardized or nonjeopardized segments.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiac Catheterization↗

PubMed1975

Response patterns to noxious and non-noxious stimuli in rostral trigeminal relay nuclei.

Postimulus time histogram analysis of second-order neuron responses in rostral trigeminal relay nuclei of cat demonstrated characteristic firing patterns after noxious (tooth pulp) and non-noxious (tooth tap) stimuli. The response to noxious stimulation was prolonged and frequently bimodal while the response to non-noxious stimulation was brief. The same neurons were fired by electrical stimuli applied directly to nucleus caudalis but with longer latencies suggesting a contributory role of nucleus caudalis to the characteristic prolonged bimodal response pattern to noxious stimuli. Interacting noxious and non-noxious stimuli using condition-test sequences demonstrated further stimulus mode-related changes in firing patterns. Electrical conditioning stimuli in nucleus caudalis reduced some responses while strychnine sulfate applied into nucleus caudalis augmented the responses evoked in rostral nuclei by both noxious and non-noxious peripheral stimuli. Nucleus caudalis appeared to contain elements which may modulate activity in rostral trigeminal nuclei by either augmenting or reducing specific firing patterns of second-order neurons in rostral relay nuclei.

Animals↗

PubMed1983

Correlation of sequence hydrophobicities measures similarity in three-dimensional protein structure.

The degree of similarity in the three-dimensional structures of two proteins can be examined by comparing the patterns of hydrophobicity found in their amino acid sequences. Each type of amino acid residue is assigned a numerical hydrophobicity, and the correlation coefficient rH is computed between all pairs of residues in the two sequences. In tests on sequences from two properly aligned proteins of similar three-dimensional structures, rH is found in the range 0.3 to 0.7. Improperly aligned sequences or unrelated sequences give rH near zero. By considering the observed frequency of amino acid replacements among related structures, a set of optimal matching hydrophobicities (OMHs) was derived. With this set of OMHs, significant correlation coefficients are calculated for similar three-dimensional structures, even though the two sequences contain few identical residues. An example is the two similar folding domains of rhodanese (rH = 0.5). Predictions are made of similar three-dimensional structures for the alpha and beta chains of the various phycobiliproteins, and for delta hemolysin and melittin.

Amino Acid Sequence↗