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Biomedical subjects

K Wang

Publications and source records attributed to K Wang.

At least 397 records · Page 22Linked to original sources
PubMed1995

Estrogen augments serotonergic activity in postmenopausal women.

To investigate the influence of estrogen replacement on serotonergic activity in postmenopausal women, the serotonin agonist meta-chlorophenylpiperazine (m-CPP) (0.5 mg/kg) was given orally to 18 normal postmenopausal women, 11 of whom were also tested following 30 days' treatment with estrogen transdermal patches (estraderm 0.1 mg). Fifteen normal, healthy women of reproductive status served as a control group. Cortisol and prolactin responses to m-CPP were measured. Without estrogen, the prolactin and cortisol responses of postmenopausal women to m-CPP were blunted compared to those of reproductive women. Estrogen replacement increased the hormonal responses. It is suggested that decreased serotonergic activity in postmenopausal women might contribute to their vulnerability to affective disorders. Estrogen replacement therapy might decrease this vulnerability and might add to the efficacy of serotonergic antidepressants when warranted.

Administration, Cutaneous↗
PubMed1995

A microtiter plate-based high-throughput DNA purification method.

A fast, reliable, inexpensive, and high-throughput method to purify DNA has been developed. It is based on DNA amplification by polymerase chain reaction utilizing a mini spin-column made from a 96-well membrane-bottomed assay plate. With this method, 50% of the DNA is recovered routinely using Sephacryl-500HR as filtration media. Purified DNA can then be used in various enzymatic manipulations, such as sequencing and hybridization. This provides an economical alternative protocol for routine large-scale purification of DNA templates for sequencing or other enzymatic manipulations.

Base Sequence↗
PubMed1995

Pairwise end sequencing: a unified approach to genomic mapping and sequencing.

Strategies for large-scale genomic DNA sequencing currently require physical mapping, followed by detailed mapping, and finally sequencing. The level of mapping detail determines the amount of effort, or sequence redundancy, required to finish a project. Current strategies attempt to find a balance between mapping and sequencing efforts. One such approach is to employ strategies that use sequence data to build physical maps. Such maps alleviate the need for prior mapping and reduce the final required sequence redundancy. To this end, the utility of correlating pairs of sequence data derived from both ends of subcloned templates is well recognized. However, optimal strategies employing such pairwise data have not been established. In the present work, we simulate and analyze the parameters of pairwise sequencing projects including template length, sequence read length, and total sequence redundancy. One pairwise strategy based on sequencing both ends of plasmid subclones is recommended and illustrated with raw data simulations. We find that pairwise strategies are effective with both small (cosmid) and large (megaYAC) targets and produce ordered sequence data with a high level of mapping completeness. They are ideal for finescale mapping and gene finding and as initial steps for either a high- or a low-redundancy sequencing effort. Such strategies are highly automatable.

Base Composition↗
PubMed1995

Nebulette: a 107 kD nebulin-like protein in cardiac muscle.

A 107-kD protein has been identified in primary cultures of chicken embryonic cardiomyocytes by immunoprecipitations with certain anti-nebulin monoclonal antibodies (mAbs). These mAbs, prepared against a fragment of human skeletal muscle nebulin located near the carboxyl terminus, detect a 107-kD protein in extracts of adult chicken heart, adult mouse heart, and adult rabbit heart by immunoblot analysis. A partial cDNA corresponding to this protein has been isolated by immunological screening of a chicken heart cDNA expression vector library. The partial cDNA encodes a 380-amino acid open reading frame composed entirely of nebulin-like 35-residue modules marked by the highly conserved sequence motifs: SXXXYK and TPD. The open reading frame exhibits 60-85% homology with skeletal muscle nebulins from a variety of species. This cDNA recognizes an approximately 8-kb transcript in cardiac RNA and does not hybridize to skeletal muscle RNAs by northern analysis. Immunofluorescence localization of this nebulin-like protein in primary cultures of chicken cardiomyocytes and embryonic chicken cardiac myofibrils indicates that the protein is localized to the I-Z-I complex of the myofibrils, extending approximately 25% of the thin filament length. Comparisons of the distribution of this protein relative to actin, myosin, and titin in spreading cardiomyocytes suggest that the cardiac nebulin-like protein becomes aligned with the nascent myofibrils early during myofibrillogenesis. To distinguish this petite nebulin-like protein from the 600-900 kD skeletal muscle nebulin, we have named it nebulette.

Animals↗
PubMed1995

The effect of cisplatin and transplatin on the conformation and association of F-actin.

The effects of cisplatin and transplatin on the conformation and association of F-actin were studied by ESR, turbidimetry and CD measurement. The results indicate that the major component affecting F-actin secondary conformation is derived from their effect on the tertiary or quaternary conformation and association states of F-actin. The effect of platinum is seen by the fact that binding of cisplatin causes first an increase in molecular size followed by a later decrease. The induction time for the association depended on the concentration of cisplatin. Transplatin was able to reach the target site more readily, resulting in the dissociation of F-actin even at a very low concentration.

Actins↗
PubMed1995

Tb3+ binding to human erythrocyte spectrin resulting in conformation change and aggregation.

The Tb3+ binding to spectrin tetramer (SPT) was studied by Tb3+ fluorescence titration and CD spectra. The results indicated that the total high-affinity Tb3+ binding sites are n1 = 330, with average Kd = 3.6 x 10(-6) M. Among them, ca. 90 sites are of higher affinity and are probably more specific to Tb3+ than the remaining sites. There are 520 low affinity Tb3+ binding sites with average Kd = 1.5 x 10(-5) M. Fluorescence and CD spectra revealed that the alpha-helix content of SPT decreased with Tb3+ binding to specific sites and further binding did not result in conformation change. Tb3+ binding to SPT and the subsequent reactions were studied by employing stopped-flow fluorescence and light scattering methods. The studies demonstrate that this is a multistep reaction assembly: high-affinity terbium binding-conformation change-aggregation-low-affinity terbium binding--the second conformation change. The critical Tb3+ concentration-induced spectrin dimer (SPD) aggregation was determined with a light scattering method.

Binding Sites↗
PubMed1995

Phosphorylation of alpha-crystallin in rat lenses is stimulated by H2O2 but phosphorylation has no effect on chaperone activity.

Alpha crystallin (alpha), a phosphorylated structural protein of the lens, has been shown to be a chaperone preventing other lens proteins from aggregating. It is now demonstrated that with oxidative stress imposed on cultured rat lenses, the incorporation of labeled phosphate into the alpha polypeptide chains increased by two to four times over a 90-min period in comparison to control experiments. The phosphorylation rate of the B chain, alpha B, was twice that of the A chain, alpha A. However, phosphorylation of the alpha chains has an insignificant effect on the chaperone activity of alpha or the individual alpha A and alpha B chains as measured by suppressing the thermally induced aggregation of beta low or gamma crystallins. It was also found that the alpha A aggregates are more effective chaperones than the alpha B aggregates. The size of the macromolecules resulting from reaggregation of the isolated non-phosphorylated or phosphorylated alpha B chains are not markedly effected by phosphorylation. However, phosphorylation of the alpha A chain leads to a heterogeneous population with two major species, one similar in size to alpha A and another approximately twice as large. It is concluded that the phosphorylation of alpha is associated with some other function of the protein than that of chaperone activity and that this function may be linked to a protective response to oxidative stress.

Animals↗
PubMed1995

Effects of needle age, long-term temperature and CO(2) treatments on the photosynthesis of Scots pine.

Naturally regenerated 20-25-year-old Scots pine (Pinus sylvestris L.) trees were grown in open-top chambers in the presence of an elevated temperature or CO(2) concentration, or both. The elevated temperature treatment was administered year-round for 3 years. The CO(2) treatment was applied between April 15 and September 15 for 2 years. The photosynthetic responses of 1- and 2-year-old needles to varying photon flux densities (0-1500 micro mol m(-2) s(-1)) and CO(2) concentrations (350, 700 and 1400 micro mol mol(-1)) during measurement were determined. The CO(2) treatment alone increased maximum photosynthetic rate and light-use efficiency, but decreased dark respiration rate, light compensation and light saturation regardless of needle age. In contrast, the temperature treatment decreased maximum photosynthetic rate and photosynthetic efficiency, but increased dark respiration rate, light compensation and light saturation. The aging of needles affected the photosynthetic performance of the shoots; values of all parameters except photosynthetic efficiency were less in 2- than in 1-year-old needles. The CO(2) treatment decreased and the temperature treatment enhanced the reduction in maximum photosynthesis due to needle aging.

Journal Article↗
PubMed1995

Treatment of duodenal carcinoid by strip biopsy.

In a 70-year-old man with diarrhea and weight loss, upper gastrointestinal endoscopy showed a 0.4-cm nodular lesion at the anterior duodenal bulb with a fissure at the tip of the lesion. The histologic diagnosis of the biopsied specimen revealed a duodenal carcinoid confined to the submucosa. We used strip biopsy to resect the lesion. After resection, diarrhea subsided and weight was increased. Strip biopsy may be a safe and effective choice for management of a duodenal carcinoid if it is < 1 cm in size or confined to the submucosa, especially when mitoses are absent.

Aged↗
PubMed1995

Octreotide and heater probe thermocoagulation for arrest of peptic ulcer hemorrhage. A prospective, randomized, controlled trial.

We carried out a prospective, randomized, controlled trial over a 7-month period to assay the hemostatic effects of octreotide and heater probe thermocoagulation (HPT) in 54 patients with active peptic ulcer bleeding or nonbleeding visible vessels at the ulcer base. Nineteen patients received octreotide 100 micrograms bolus i.v. followed by 25 micrograms/h i.v. for 3 days. Twenty patients received HPT. Fifteen patients received ranitidine 100 mg i.v. every 12 h. The three groups were matched for sex, age, location of bleeders, endoscopic findings, shock, and initial hemoglobin. Ultimate hemostasis was obtained in 11 (58%) of the octreotide group, 18 (90%) of the heater probe group, and 8 (53%) of the control group (p < 0.05). Volume of blood transfused, number of patients receiving operation, hospital stay, and number of deaths were not statistically significant among the three groups. We conclude that HPT is more effective than octreotide in the arrest of peptic ulcer bleeding.

Aged↗
PubMed1995

Heater probe thermocoagulation and multipolar electrocoagulation for arrest of peptic ulcer bleeding. A prospective, randomized comparative trial.

Both heater probe thermocoagulation (HPT) and multipolar electrocoagulation (MPEC) are promising techniques to control peptic ulcer bleeding. However, their hemostatic effects are still not proven conclusively in controlled trials. Here we have tried to do that. Patients with a bleeding ulcer or a nonbleeding visible vessel at the ulcer base received either HPT or MPEC randomly. We compared hemostatic rates, rebleeding rates, hospital stay, volume of blood transfusion, number of operations, and mortality between both groups. A total of 80 patients entered this trial. Patients of both groups had similar ultimate hemostatic rates (HPT 92.5%, MPEC 85%), days in hospital (HPT 5.4, MPEC 5.0), volume of blood transfusion (mean values: HPT 1,774 ml, MPEC 1,974 ml), number of operations (HPT 3, MPEC 3), and mortality (HPT 2, MPEC 3). Both therapeutic approaches are safe and effective for peptic ulcer bleeding.

Aged↗
PubMed1995

Reciprocal expression of phosphoenolpyruvate carboxykinase and acute phase genes during acute inflammation.

Part of the hepatic response to injury is mediated by the expression of a gene family known as acute phase genes. Expression of acute phase genes is induced by the presence of cytokines in the circulation such as tumor necrosis factor alpha, interferon gamma, and interleukins-1 and -6. Simultaneous with the transcription of acute phase genes, there is a decrease in the expression of other genes such as albumin. In the present study, we report the decrease in transcription of the gene coding for phosphoenolpyruvate carboxykinase (PEPCK), a key regulatory enzyme in the gluconeogenic pathway, in rat liver during an acute inflammatory state induced by bacterial endotoxin. Steady-state mRNA levels of PEPCK decrease 3 h after endotoxin injection, returning to 70% of normal levels after 24 h. This decrease in PEPCK mRNA levels was due to a decline in the rate of transcription of the gene, most likely mediated by an increase in the circulating levels of insulin. However, expression of the PEPCK gene was not induced by an increase in the cellular levels of cAMP during inflammation. Such a lack of response to cAMP may be due to the inactivation of, or decrease in, the levels of the transcriptional factor(s) responsible for PEPCK transcription.

Animals↗
PubMed1995

Analysis of the promoter and cis-acting elements regulating expression of herpes simplex virus type 2 latency-associated transcripts.

In latently infected neurons, herpes simplex virus type 2 (HSV-2) expresses one abundant family of transcripts, the latency-associated transcripts (LATs). We demonstrate here that the sequence lying about 700 bp upstream of the 5' end of the HSV-2 major LAT acts as a very strong promoter in transient expression assays in both neuronal and nonneuronal cells. Transcription starts about 27 to 32 bp downstream of a functional TATA box. The proximal fragment from -102 to +34 includes the basal promoter and accounts for constitutive transcriptional activity in various cell lines. The distal region from -392 to -103 contributes to particularly strong promoter activity in neuronal cell lines and involves multiple cis-acting elements. A functional activating transcription factor/cyclic AMP (cAMP) response element binding protein motif lies just upstream of the TATA. By DNase I footprint and methylation protection assays, we identified several additional protein-binding sites upstream of the activating transcription factor/cAMP response element binding protein motif. A GC-rich element, termed LAT-3, was located between bases -128 to -102. A 2-bp substitution in LAT-3 markedly reduced promoter activity and abolished protein-binding ability in vitro. Gel retardation assay showed no competition for protein binding to LAT-3 by other GC-rich elements. LAT-3 appears to be a novel cis-acting element that may contribute to the neuronal responsiveness of the HSV-2 LAT promoter.

Animals↗
PubMed1995

Architecture of atrial musculature in humans.

OBJECTIVE: To investigate the gross arrangement of the principal muscular bundles of the two atria, and to suggest how it may contribute to contraction and spread of atrial excitation. DESIGN: A prospective analysis based on anatomical examination of adult human hearts. SETTING: A national heart and lung institute and a tertiary referral centre for cardiac disease. MATERIAL: 9 normal postmortem human hearts. METHODS: Dissection of atrial muscles with macrophotography. RESUltS--The atrial walls consist of circumferential and longitudinal muscular bundles, the former being arranged at the base of the atria with the latter predominating in the parietal walls. The muscular bundles in the right atrium are larger than those in the left. The main muscles forming the right atrial wall are the terminal crest and terminal pectinate muscles. The terminal crest, the most obvious muscle, is arranged longitudinally with its pectinate muscles connecting to the musculature of the atrioventricular vestibule. No structure resembling the terminal crest is seen in the left atrium. Instead the left atrial wall is composed of intermingled series of muscles, chief of these being the interatrial band and the septoatrial bundle. The former is arranged circumferentially at the atrial base, while the latter is mainly longitudinal. The wall of the right atrium is not of uniform thickness because of the presence of the terminal crest and its pectinate muscles on its internal surface. By contrast, the left atrial wall is much more uniform and its average thickness is greater than that of the right atrium. The rim of the oval fossa is the most important muscular structure on the septal surface and is formed by the infolded atrial walls. The other principal muscles of the atria attach to it, so that the rim provides mechanical support for overall movement of the atrial walls. Comparison of the gross arrangement of the atrial musculature with earlier echocardiographic measurements showed that this arrangement of the muscle explains movement of the atrioventricular ring and overall atrial contraction, and provides a suitable substrate for preferential conduction. CONCLUSION: The anatomical features of the atrial musculature explain the known facts concerning atrial contraction and preferential conduction.

Autopsy↗
PubMed1995

Atrial electromechanical sequence in normal subjects and patients with DDD pacemakers.

OBJECTIVE: To assess the effect of right atrial appendage pacing on atrial electromechanical interrelations in patients with DDD pacemakers. DESIGN: Prospective study by M mode echocardiogram, Doppler echocardiogram, and apexcardiogram, along with electrocardiogram and phonocardiogram. SETTING: Tertiary cardiac referral centre. PATIENTS: 20 patients with DDD pacemakers and 20 age matched normal controls. RESULTS: Age, RR interval, atrial size, left ventricular size, and fractional shortening were similar in the two groups. Atrial electromechanical delay (the time from the onset of P wave or atrial pacing spike on ECG to the onset of atrial contraction on M mode echogram) was 68 (SD 7) ms at the lateral site of right atrium, 82 (9) ms at the central fibrous body, 93 (11) ms at the lateral site of left atrium in normals. In patients with DDD pacing, however, this delay increased to 85 (22) ms, 117 (23) ms, and 138 (25) ms respectively (all P < 0.01). Interatrial mechanical delay (the time from the onset of right atrial motion to the onset of the left) increased from 25 (6) ms in normal controls to 53 (18) ms in patients (P < 0.01). Intra-atrial mechanical dispersion (the time from the earliest to the latest onset of regional atrial motion around the atrioventricular ring) in the right atrium increased from 6 (2) ms in normals to 19 (2) ms in patients (P < 0.01), but it remained unchanged in the left atrium (6 (2) ms in normal controls v 7 (2) ms in patients, P > 0.05). Peak atrial shortening rate was not different between the two groups. Differences of atrial electromechanical activity between the two groups were also reflected on Doppler echocardiogram and apexcardiogram. CONCLUSIONS: Right atrial appendage pacing disturbs the normal coordinate sequence of right atrial mechanical activity and leads to a striking and variable increase in intra-atrial conduction time as well as in interatrial conduction time. Left atrial contraction remains synchronous although the timing of the start of its contraction was delayed. These values can be determined in individual patients to allow optimal setting of DDD pacemakers.

Aged↗
PubMed1995

Non-invasive detection of left atrial mechanical failure in patients with left ventricular disease.

OBJECTIVE: To define patients with left atrial mechanical failure and identify its echocardiographic, physiological, and clinical associations. DESIGN: Prospective study with cross sectionally guided M mode and Doppler echocardiograms, and with apexcardiograms, electrocardiograms, and phonocardiograms. SETTING: Tertiary cardiac referral centre. PATIENTS: 10 patients with left atrial mechanical failure and 20 healthy controls of similar age. RESULTS: 10 patients with left atrial mechanical paralysis were identified among 4036 adults over a 1 year interval. Nine were in sinus rhythm and one had a DDD pacemaker. Left atrial mechanical activity was absent on M mode echocardiograms of the left sided atrioventricular ring and the aortic root. A Doppler A wave on transmitral flow and a clearly defined A wave on the left ventricular apexcardiogram were also absent, though evidence of right atrial mechanical movement was present in nine patients. Mean (SD) age was 63 (19) years and six were men. Nine had left ventricular disease and one had undergone extensive resection of the left atrium. Abnormal measurements of left ventricular end diastolic dimension (62 (13) mm), fractional shortening (15 (6)%), isovolumic relaxation time (19 (12) ms), left atrial size (45 (10) mm), and transmitral Doppler E wave deceleration time (110 (35) ms) were recorded. CONCLUSION: Left atrial mechanical failure may be present in patients with left ventricular disease despite normal sinus rhythm. Normal atrial activation on 12 lead electrocardiogram suggests it is primarily mechanical in origin. The possibility of left atrial mechanical failure must be considered when Doppler patterns of transmitral flow are used to assess left ventricular diastolic function.

Adult↗