Measurements of deuteron threshold electrodisintegration: A probe of short-range meson exchange.
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Journal Article↗
Biomedical subjects
K Wang
Publications and source records attributed to K Wang.
Regulation of skeletal muscle stiffness and elasticity by titin isoforms: a test of the segmental extension model of resting tension.
To explore the role of titin filaments in muscle elasticity, we measured the resting tension-sarcomere length curves of six rabbit skeletal muscles that express three size classes of titin isoform. The stress-strain curves of the split fibers of these muscles displayed a similar multiphasic shape, with an exponential increase in tension at low sarcomere strain followed by a leveling of tension and a decrease in stiffness at and beyond an elastic limit (yield point) at higher sarcomere strain. Significantly, positive correlations exist between the size of the expressed titin isoform, the sarcomere length at the onset of exponential resting tension, and the yield point of each muscle. Immunoelectron microscopic studies of an epitope in the extensible segment of titin revealed a transition in the elastic behavior of the titin filaments near the yield point sarcomere length of these muscles, providing direct evidence of titin's involvement in the genesis of resting tension. Our data led to the formulation of a segmental extension model of resting tension that recognizes the interplay of three major factors in shaping the stress-strain curves: the net contour length of an extensible segment of titin filaments (between the Z line and the ends of the thick filaments), the intrinsic molecular elasticity of titin, and the strength of titin thick filament anchorage. Our data further suggest that skeletal muscle cells may control and modulate stiffness and elastic limit coordinately by selective expression of specific titin isoforms.
Animals↗
Nebulin as a giant actin-binding template protein in skeletal muscle sarcomere. Interaction of actin and cloned human nebulin fragments.
Nebulin is a family of giant sarcomere matrix proteins of 600-900 kDa in most vertebrate skeletal muscles. Recent sequence analysis suggests that human nebulin is mainly composed of a large number (greater than 200) of conserved repeats of approximately 35 residues. Two cloned nebulin fragments, consisting of 6 and 8 of the repeats, have been expressed in E. coli using the pET3d vector. Both F-actin cosedimentation and solid-phase binding assays demonstrated a specific binding of these nebulin fragments to actin. This finding suggests that nebulin is a giant protein which binds actin at multiple sites in a template-manner. The presence of an actin-binding template protein in the skeletal muscle sarcomere may have significant implications in the assembly and function of the contractile apparatus.
Actins↗
Strands hybridize in postreplicative adenovirus overlap recombination.
We describe a postreplicative mechanism for adenovirus overlap recombination. An adenovirus minichromosome system was used to study overlap recombination driven by adenovirus DNA replication. Crossing-over appeared to occur equally at, but not within, the borders of the overlap between partner molecules. We propose that recombination in the minichromosome system proceeds through an intermediate formed by direct hybridization of complementary sequences on displaced strands generated by adenovirus-specific DNA replication. Some, but not all, heterologous regions in the intermediate are susceptible to mismatch correction. This pathway is intrinsically nonreciprocal and differs significantly from other adenovirus recombinational mechanisms that have been described previously.
Adenoviruses, Human↗
Diagnosis of polyhydramnios in early gestation: indication for prenatal diagnosis?
Previously published reports have indicated that idiopathic polyhydramnios may be associated with trisomies 18 and 21 and that chromosomal analysis is indicated. Furthermore, the natural history and fetal outcome of polyhydramnios diagnosed in early gestation have not been well delineated. We identified 138 pregnancies with polyhydramnios prior to 26 weeks' gestation. Of 131 complete cases, 21 were diagnosed as severe, 18 as moderate, and 92 as mild polyhydramnios. Congenital abnormalities were noted in 18 of 21 severe cases (86 per cent). Two of the remaining three cases were twin-to-twin transfusion. Thirteen of 18 cases with moderate polyhydramnios (72 per cent) were associated with anomalies; six of the remaining cases were twin-to-twin transfusion. Sixteen of 92 cases of mild polyhydramnios (17 per cent) were associated with congenital abnormalities. In 69 of 76 cases of mild hydramnios not associated with anomalies (91 per cent), the hydramnios resolved prior to delivery. Only 2 of 16 (13 per cent) associated with anomalies resolved. In 4 of 5 cases (80 per cent) with moderate hydramnios and no anomalies, the amniotic fluid volume was normal on subsequent ultrasound. No case of moderate polyhydramnios associated with anomalies or maternal conditions nor any case of severe polyhydramnios resolved. There were seven cases of chromosomal abnormalities in this series; all were associated with sonographic findings in addition to the presence of polyhydramnios. On the basis of these data, we doubt the benefit of amniocentesis following the early diagnosis of idiopathic polyhydramnios in the absence of other ultrasound findings.
Chromosomes, Human, Pair 17↗
Pseudo AV block secondary to concealed premature His bundle depolarizations.
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Bundle of His↗
Inverted repeats direct repair of adenovirus minichromosome ends.
Adenovirus DNA initiates strand-displacement replication from origins located in identical inverted terminal repetitions (ITRs). Panhandle structures, formed by base pairing between ITRs on the displaced strands, have been proposed as replication intermediates for complementary strand synthesis. We have used a model system, which separates adenovirus replication origin sequences from those involved in panhandle formation, to study the length and sequence integrity of panhandles. By making a series of unidirectional deletion in the panhandle sequence, we show that 31 bp are necessary for panhandle formation. Removal of long stretches of 3'-unpaired nucleotides distal to the panhandle is extremely efficient. Our results argue for the formation of panhandles during adenovirus DNA replication and provide a mechanism for maintaining sequence identity between distantly located inverted repetitions. The size constraint may explain why the adenovirus ITRs are larger than the viral DNA replication origins.
Adenoviridae↗
Nebulin as a length regulator of thin filaments of vertebrate skeletal muscles: correlation of thin filament length, nebulin size, and epitope profile.
Nebulin, a family of giant proteins with size-variants from 600 to 900 kD in various skeletal muscles, have been proposed to constitute a set of inextensible filaments anchored at the Z line (Wang, K., and J. Wright. 1988. J. Cell Biol. 107:2199-2212). This newly discovered filament of the skeletal muscle sarcomere is an attractive candidate for a length-regulating template of thin filaments. To evaluate this hypothesis, we address the question of coextensiveness of nebulin and the thin filament by searching for a correlation between the size of nebulin variants and the length distribution of the thin filaments in several skeletal muscles. A positive linear correlation indeed exists for a group of six skeletal muscles that display narrow thin filament length distributions. To examine the molecular and architectural differences of nebulin size-variants, we carried out immunoelectron microscopic studies to map out epitope profiles of nebulin variants in these muscles. For this purpose, a panel of mAbs to distinct nebulin epitopes was produced against rabbit nebulin purified by an improved protocol. Epitope profiles of nebulin variants in three skeletal muscles revealed that (a) nebulin is inextensible since nebulin epitopes maintain a fixed distance to the Z line irrespective of the degree of sarcomere stretch; (b) a single nebulin polypeptide spans a minimal distance of 0.9 microns from the Z line; (c) nebulin contains repeating epitopes that are spaced at 40 nm or its multiples; (d) nebulin repeats coincide with thin filament periodicity; (e) nebulin variants differ mainly at either or both ends; and (f) nebulin remains in the sarcomere in actin-free sarcomeres produced by gelsolin treatment. Together, these data suggest that nebulin is an inextensible full-length molecular filament that is coextensive with thin filaments in skeletal muscles. We propose that nebulin acts as a length-regulating template that determines thin filament length by matching its large number of 40-nm repeating domains with an equal number of helical repeats of the actin filaments.
Animals↗
Sensory urgency: how full is your bladder?
OBJECTIVE: To investigate whether women with sensory urgency have an abnormal perception of bladder fullness. DESIGN: Prospective observational study. SETTING: Urodynamic Unit, St George's Hospital, London. SUBJECTS: 15 women with sensory urgency, 15 women with idiopathic detrusor instability and 15 without symptoms of frequency or urgency (control group). INTERVENTIONS: All the women attended for cystometry. Each was asked to complete a visual analogue score of how full she perceived her bladder to be on a scale from 1 to 10. This was done before filling cystometry and at three times during bladder filling. At each time actual filled volume was noted. MAIN OUTCOME MEASURES: Maximum bladder capacity and individual perception of bladder fullness. RESULTS: Women with sensory urgency and detrusor instability had similar maximum bladder capacity although values in both groups were significantly lower than in the control group; thus percentage of maximum bladder capacity was used for analysis. Linear regression was performed for each group of patients and a predicted visual analogue score at 25, 50 and 75% of capacity calculated. These were compared between groups by rank analysis of variance. There was no significant difference between sensory urgency and detrusor instability. However, at 25, 50 and 75% of capacity, both groups had a significantly higher score than the control group. CONCLUSIONS: This abnormal perception would explain symptoms of frequency and urgency in these two groups. These results also confirm the similarity between detrusor instability and sensory urgency.
Adult↗
Effectiveness of zinc bacitracin on production traits and energy metabolism of heat-stressed hens compared with hens kept under moderate temperature.
Two experiments with a total of 100 White Leghorn hens (26 to 59 wk of age) and 120 Rhode Island Red chickens (4 to 12 wk of age) were conducted to study the effect of 100 mg zinc bacitracin (ZBA)/kg of feed on hens and chickens acclimatized to 20 or 34 C environments. Layers were provided ad libitum access to a diet containing 11.12 MJ ME/kg (1 MJ = .239 Mcal) and 174 g CP/kg supplemented with 0 and 100 mg ZBA/kg. Body weight gain, egg number, total egg mass, and feed efficiency of ZBA-treated hens kept at a moderate temperature (20 C) were not significantly improved by 3.5, 2.6, 3.3, and 3.1%, respectively. However ZBA supplementation induced a more pronounced increase in performance in heat-stressed hens. The respective traits were significantly improved by 66.3, 15.4, 16.9, and 5.9%. Additionally, treated hens maintained at 34 C consumed significantly more feed than untreated hens. Eggshell breaking strength of treated hens held under normal conditions was not significantly improved. Feeding ZBA to heat-stressed hens led to a statistically higher breaking strength. Supplementation with ZBA for hens acclimatized to 20 and 34 C reduced fasting heat production by 4.1 and 7.6%, respectively. However, in the 20 C environment the differences were significant at only one of seven ages. The upper critical temperature (UCT) of ZBA-treated hens increased significantly at both temperatures from 34 to 42 wk of age relative to the control group. No significant effects of ZBA on UCT were observed at 24 to 32 wk and 40 to 52 wk of age.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
Non-0:1 Vibrio cholerae bacteremia: a case report and literature review.
We reported a case of non-0:1 group Vibrio cholerae septicemia with myelodysplatic syndrome in Taiwan. We also reviewed the other 22 reported cases of non-0:1 Vibrion cholerae septicemia found in the literature regarding its pathogenesis and treatment. The case mortality rate of these 23 cases was 47.8%. Most of them had immunocompromised diseases, particularly liver cirrhosis and hematologic malignancy. Therefore, the most important factor is the host defense. The cholera-like enterotoxin and E1-Tor-like hemolysin also play a major role, but whether the gall bladder plays a role in organ growth is still unclear. The incidence of gastroenteritis is not well understood because of the low incidence of non-0:1 V. cholerae gastroenteritis as compared with other factors such as shell-fish eating. Ampicillin as the sole antibiotic for non-0:1 V. cholerae is not efficacious. Tetracyclines or chloramphenicol is more effective for treatment.
Aged↗
Tolerance induction by liver grafting and FK 506 treatment in nonhuman primates.
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Animals↗
[Studies on serum levels of normal and cholesterol-fed Beijing duck apo A-I and apo B].
Rabbit anti-Beijing duck apo A-I and apo B antisera were prepared by immunizing New Zealand rabbits with duck apo A-I and LDL, respectively. Rocket immunoelectrophoresis and radial immunodiffusion were used to determine the serum levels of apo A-I and apo B of 55 normal Beijing ducks and 8 cholesterol-fed Beijing ducks. Normal ducks contained about 145 mg apo A-I and 73 mg apo B per 100 ml serum; cholesterol-fed ducks contained about 167 mg apo A-I and 75 mg apo B per 100 ml serum.
Animals↗
Characterization of sodium-selective optode membranes based on neutral ionophores and assay of sodium in plasma.
Plasticized poly(vinyl chloride) membranes that incorporate a highly lipophilic sodium-selective neutral ionophore (ETH 4120) and novel H(+)-selective chromo-ionophores, lipophilic isologs of Nile Blue, are used in the competitive binding of Na+ and H+ for a reversible, optical determination of sodium activities in buffered solutions at different selected pH values. These optode membranes are used to assay total sodium concentrations in pH-buffered human blood plasma.
Electrodes↗
[Identification of Schisardra by TLC-densitometry].
This paper deals with the determination of the lignins in 10 species of Schisandra crude drugs by TLC-densitometry. The result shows that all the 10 species are unidentical in the lignin constituents; the same species vary in the contents with habitats; and the TLC chromatograms of the 10 species differ distinctly from each other.
Chromatography, Thin Layer↗
An analysis of neuronal responses in nucleus centrum medianum to electrical stimulation of the superficial peroneal nerve.
Excitatory and inhibitory responses recorded extracellularly in neurons at various levels of the central nervous system induced by electrical noxious stimulation of peripheral nerves were frequently reported in studies on the mechanisms of acupuncture analgesia. However, the correlation between the responses and excitation of distinct afferent fibers was rarely investigated. The question whether the responses mentioned above are truly nociceptive in property is of significance to answer, and this is what we want to clarify in the present study. Sixty five neurons responding to electrical stimulation of the left superficial peroneal nerve were extracellularly recorded in the nucleus centrum medianum (CM) contralateral to the stimulation in 34 cats paralyzed with gallamine triethiodide and ventilated artificially under anaesthetics. Peristimulus histograms of the responses of CM neurons were plotted correspondingly, to the excitation of A delta and C-fibers, which was monitored by means of compound action potentials. To identify the nociceptive property of the responses ketamine or morphine was intravenously administered in some cases, capsaicin was topically applied at the superficial peroneal nerve proximal to the stimulated location in a few cases. Besides, the effect of electroacupuncture (EA) at Zusanli (St36) and Huantiao (GB30) points on the responses was observed. A total of 65 CM neurons recorded included 55 excited and 10 inhibited neurons.(ABSTRACT TRUNCATED AT 250 WORDS)
Action Potentials↗
Menstrual irregularities associated with bupropion treatment.
The authors report two cases of menstrual irregularities associated with bupropion treatment. This is the first report of such an association, and it is supported by data collected by the Burroughs Wellcome Co. Since the mode of action of this effective new antidepressant is basically unknown and does not operate through any of the putative mechanisms of the classical antidepressants, its side effect profile is of heuristic as well as practical importance.
Adult↗
Rapid restriction map constructions using a modified pWE15 cosmid vector and a robotic workstation.
This paper describes a number of techniques for rapid restriction mapping of cosmid clones. First, we have replaced the cloning site of cosmid vector pWE15 with a polylinker containing 15 infrequently cleaved restriction enzyme sites that are placed asymmetrically on each side of the BamHI cloning site. DNA cloned into this vector can be fully recovered by using several pairs of restriction enzymes. Second, we have designed a simple electrical circuit device that allows the performance of asymmetric voltage gradient field inversion gel electrophoresis (AFIGE) to improve the resolution of DNA molecules in the range of 20-50 kbp. AFIGE can be obtained by simply placing the device in between a commercially available switching unit and the gel box in a standard field inversion system. Finally, the restriction digestion procedure has been automated by using a Beckman Biomek 1000 robotic workstation. Using this automated system, 96 restriction reactions, including gel loading, can be performed in less than two hours. In summary, these methods represent at least a tenfold improvement in the speed and/or mapping data that can be obtained in a single gel.
Animals↗