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Biomedical subjects

E Yeung

Publications and source records attributed to E Yeung.

At least 19 recordsLinked to original sources
PubMed2001

A proteinase inhibitor II of Solanum americanum is expressed in phloem.

Although proteinase inhibitor proteins are known to confer insect resistance in transgenic plants, their endogenous roles remain undefined. Here, we describe the expression of a proteinase inhibitor II (PIN2) protein from Solanum americanum in phloem of stems, roots and leaves suggesting a novel endogenous role for PIN2 in phloem. The phloem consists of parenchyma cells, sieve elements (SE), and companion cells (CC) which are in close association with SE. We isolated two cDNAs encoding PIN2, SaPIN2a and SaPIN2b, from a S. americanum cDNA library using a tomato PIN2 cDNA as hybridization probe. SaPIN2a shows 73.6% identity to SaPIN2b. Southern blot analysis confirmed that two genes occur in S. americanum. Northern blot analysis showed that both are wound-inducible and are expressed in flowers. Unlike SaPIN2b and other previously characterized plant PIN2 proteins, SaPlN2a is abundantly expressed in stems. In situ hybridization studies on stem sections showed that SaPIN2a mRNA is expressed in CC and some SE, likely the immature developing SE. of external and internal phloem. Western blot analysis using SaPIN2a-specific antibodies showed SaPIN2a accumulation in stems, leaf midribs and fruits. Immunohistochemical localization, using these antibodies, revealed SaPIN2a expression in external and internal phloem of stem. Immunoelectron microscopy of stem, root and leaf sections further localized SaPIN2a to the CC and predominantly to the SE, particularly the parietal cytoplasm adjacent to the cell wall, the lumen and the sieve-area pores. These results suggest that, other than a possible role in plant defense, SaPIN2a could be involved in regulating proteolysis in the SE.

Amino Acid Sequence↗
PubMed2001

Field measurements of electromagnetic interference in hearing aids.

This investigation was a preliminary field study to determine the acoustic and perceptual characteristics of hearing aid distortion generated by digital wireless telephones, the usability of the telephones under field conditions, and the extent of bystander interference under field conditions. A two-channel analog-to-digital converter was used to monitor voltages generated by an acoustic (real-ear) and electromagnetic probe. Digital recordings of interference and speech plus interference were made on a laptop computer. Fifty-three hearing aid wearers listened to interference and speech plus interference through personal communication service 1900 and time division multiple access digital wireless telephones and rated them in terms of annoyance experienced and usability of the wireless telephone. Ratings of annoyance were also done for the bystander condition. Approximately 80 percent of the sample rated the telephones as unusable; on the other hand, 70 to 90 percent experienced no annoying interference from telephones being used by another person seated nearby (bystander condition).

Acoustic Stimulation↗
PubMed1998

Characteristics of psychiatrists who perform ECT.

OBJECTIVE: Use of ECT is highly variable, and previous study has linked its availability to the geographic concentration of psychiatrists. However, less than 8% of all U.S. psychiatrists provide ECT. The authors analyzed the characteristics of psychiatrists who use ECT to understand more fully the variation in its use and how changes in the psychiatric workforce may affect its availability. METHOD: Data from the 1988-1989 Professional Activities Survey were examined to investigate the influence of demographic, training, clinical practice, and geographic characteristics on whether psychiatrists use ECT. RESULTS: Psychiatrists who provided ECT were more likely to be male, to have graduated from a medical school outside the United States, and to have been trained in the 1960s or 1980s rather than the 1970s. They were more likely to provide medications than psychotherapy, to practice at private rather than state and county public hospitals, to treat patients with affective and organic disorders, and to practice in a county containing an academic medical center. CONCLUSIONS: Demographic and training characteristics significantly influence whether a psychiatrist uses ECT. Opposing trends in the U.S. psychiatric workforce could affect the availability of the procedure. Expanding training opportunities for ECT and making education, training, and testing more consistent nationwide could improve clinicians' consensus about ECT and narrow variation in its use.

Confidence Intervals↗
PubMed1998

Tripartite involvement in health care clinical education.

This paper discusses the importance of an appropriate student-clinical educator-university lecturer (tripartite) relationship in clinical education and substantiates this importance with the experiences of the dynamics of such relationship in a physiotherapy course.

Faculty↗
PubMed1996

Inflammatory pseudotumour of the spleen.

Inflammatory pseudotumours are benign tumour-like masses of unknown aetiology that show microscopically a range of inflammatory and reactive responses and are of importance because they may be mistakenly identified as neoplasms. This case report describes a 15 year old girl with a cystic inflammatory pseudotumour of the spleen in whom a partial splenectomy was performed with a satisfactory outcome.

Adolescent↗
PubMed1995

Agalactosyl IgG and antibody specificity in rheumatoid arthritis, tuberculosis, systemic lupus erythematosus and myasthenia gravis.

Agalactosyl IgG (Gal(0) is a glycoform lacking terminal galactose from the oligosaccharides situated on the Fc. The percentage of circulating IgG that is Gal(0) is increased in a a number of autoimmune diseases, and in certain chronic infections associated with autoantibody production. However it is not known whether this represents decreased galactosylation of all IgG, or an increase in the relative concentration of a subset of agalactosyl antibodies of specificity relevant to the disease process. Since there is currently no way to separate agalactosyl from galactosylated IgG, we devised an assay for the relative degree of galactosylation of antibody to tetanus toxoid (TT), an antigen irrelevant to the diseases studied, and compared this value with the %Gal(0) of the whole circulating IgG. In rheumatoid arthritis (RA) and tuberculosis (TB), a raised %Gal(0) in serum IgG was reflected in a parallel rise in the extent to which antibody to TT was agalactosyl. In SLE a rise in %Gal(0) was seen in the presence of very little rise in agalactosyl anti-TT, and in myasthenia gravis (MG), where serum %Gal(0) is normal, an abnormally low percentage of the anti-TT was agalactosyl. These results imply that in RA and TB a systemic influence is downregulating the galactosylation even of irrelevant IgG. However in SLE and MG antibodies of specificities not studied here must be responsible for the %Gal(0) found in serum. It remains to be seen whether these are the autoantibodies involved in the disease process.

Antibody Specificity↗
PubMed1994

Repeated haloperidol increases both calmodulin and a calmodulin-binding protein in rat striatum.

Repeated treatment with the antipsychotic drug, haloperidol, leads to an increased behavioral sensitivity to dopamine agonists exhibited upon withdrawal from the drug. An increase in the particulate content of the endogenous Ca(2+)-binding protein, calmodulin, has been demonstrated after repeated treatment of rats with haloperidol. In this study, the anatomical specificity of the effect of repeated haloperidol treatment on the content and subcellular localization of calmodulin was investigated. Responsivity of calmodulin localization to dopaminergic input following drug treatment was assessed by determining the subcellular localization of calmodulin following an in vivo amphetamine challenge before sacrifice. Male, Sprague-Dawley rats were treated with 0.5 mg/kg haloperidol (s.c.) for 3 weeks and withdrawn from the drug for 4 days. Repeated haloperidol increased calmodulin content only in the striatum but altered the subcellular distribution of calmodulin in rat limbic forebrain and frontal cortex. In the latter areas, the soluble calmodulin was increased while the particulate calmodulin was decreased. There was no change in calmodulin in either hippocampus or cerebellum in response to drug treatment. Challenge with the dopamine mimetic, amphetamine, before sacrifice was effective in redistributing calmodulin only in striatum from rats that had been treated repeatedly with haloperidol, demonstrating an increased sensitivity of the translocation process. In order to determine whether a change in a calmodulin-binding protein would accompany the drug-induced increase in calmodulin, striatal calmodulin-binding proteins were examined using a biotinylated calmodulin overlay technique. Repeated haloperidol treatment enhanced calmodulin binding to a 150 kDa protein in striatal membranes. The 150 kDa protein exhibited the same gel mobility and subcellular distribution as myosin light chain kinase immunoreactivity. There was an increase in myosin light chain kinase immunoreactivity in striatal membranes after repeated haloperidol that was apparent in animals withdrawn either 4 or 10 days from haloperidol treatment. Therefore, repeated haloperidol could increase the rat striatal content of calmodulin and potentially that of the calmodulin-binding protein, myosin light chain kinase. Increases in striatal calmodulin and myosin light chain kinase may signal a greatly enhanced sensitivity of actin-myosin interactions after repeated haloperidol that could contribute to haloperidol-induced neurochemical or morphological changes involved in drug-induced synaptic plasticity.

Amphetamine↗
PubMed1994

High temperature microwave thermotherapy of the prostate.

Transurethral microwave thermotherapy of the prostate has been touted as a minimally invasive means of treating symptomatic prostatism. High temperatures (>55 degrees C) appear to yield improved results but require general anesthesia. To determine if high temperature thermotherapy of the prostate was feasible in an outpatient, nonanesthetic setting, we subjected men with symptomatic prostatism secondary to benign prostatic hyperplasia to treatment with a newly developed circumferentially cooled transurethral microwave thermotherapy device, the UroWave. Intraprostatic temperatures were measured on-line and treatment was targeted to achieve temperatures ranging from 45 degrees C-65 degrees C. Fifty-five men with benign prostatic hyperplasia underwent transurethral microwave thermotherapy using the UroWave in an outpatient setting without general anesthesia. Baseline mean peak urinary flow rates were 8.0 cc/sec and mean American Urology Association of the prostate displayed three distinct phases: an initial slow heating phase, a plateau phase of variable duration and a rapid secondary heating phase. The final intraprostatic temperature did not correlate with urethral or rectal temperatures or the amount of power applied. At six months, peak flow increased by 50% and symptoms score declined by 52%. Ninety-four percent of patients had a transurethral resection of the prostate-like defect at cystoscopy with a greater proportion at higher temperatures. Side effects were rare and no patients had to be admitted to hospital. Transurethral microwave thermotherapy at high intraprostatic temperatures can be achieved with general anesthesia. Symptom relief was considerable and anatomic changes resembling a transurethral resection of the prostate were noted in the majority of patients. Intraprostatic temperatures are the only means of assessing the thermal damage to the prostate and thus the effectiveness if therapy. Future studies must develop less invasive means of monitoring intraprostatic temperatures and define the role of the bladder neck. Ultimately, randomized controlled trials will define the value of this treatment.

Journal Article↗
PubMed1994

Cytomegalovirus cholangitis after renal transplantation.

Clinically significant cytomegalovirus cholangitis is well recognized in patients with AIDS but is less common in other groups of immunocompromised patients. The authors describe a 59-year-old man who had undergone renal transplantation in whom this condition developed, and they emphasize that this diagnosis should be considered in renal transplant patients presenting with biliary obstruction. Careful examination of biopsy material for cytomegalovirus inclusion bodies is necessary.

Cholangitis↗
PubMed1993

Transrectal drainage of deep pelvic collections under fluoroscopic guidance.

Although transrectal drainage of pelvic fluid collections, guided by fluoroscopy, computed tomography (CT) and ultrasonography (US), has been reported, the cumulative experience is small. The authors describe a technique for fluoroscopically guided transrectal drainage and present the results obtained for 13 patients. Each patient underwent diagnostic CT and then fluoroscopically guided drainage. A barium enema tube assembly, consisting of an enema tube, a Lunderquist PTC (percutaneous transhepatic cholangiogram) needle and a small portion of a red rubber catheter, was used to facilitate insertion of the drainage catheter. The procedure was defined as successful if complete clearance occurred after drainage, as temporizing if partial drainage was achieved and clinical improvement occurred, and as failed if the collection showed no response to drainage. Twelve of the patients had abscesses, 9 of which were successfully treated by drainage alone; one drainage was temporizing and two failed. The collection in the last patient represented a hematoma, which did not respond to drainage. The authors conclude that the technique they describe is suitable for draining moderate to large pelvic abscesses. The procedure is safe and can easily be performed in both male and female patients.

Abscess↗
PubMed1992

Accelerated gallstone dissolution in methyl tert-butyl ether by sonication. An in vitro study.

OBJECTIVES: The authors tested the effect of 195 KHz therapeutic ultrasound energy on gallstone dissolution in concert with methyl tert-butyl ether (MTBE) in vitro. METHODS: Sixteen sets of three gallstones matched for weight and appearance were selected from 16 surgically resected human gallbladders. One stone from each set was analyzed for its density pattern by computed tomography (CT) and biochemically for cholesterol content. Based on CT appearance, the stones were classified into eight noncalcified, four partially calcified, and four heavily calcified sets. The three stones were subjected to dissolution with MTBE: one with simultaneous sonication via an experimental ultrasound unit, one with manual stirring, and one acted as control without added treatment. RESULTS: Sonication reduced the dissolution time of noncalcified stones by 96% (range, 94%-98%; standard deviation [SD], 2%) relative to controls, and it was three to four times more effective than manual stirring. It was similarly effective in helping to dissolve partially calcified stones, but not heavily calcified stones. CONCLUSIONS: This study demonstrates the positive effect of sonication in accelerating gallstone dissolution with MTBE in vitro for stones without heavy calcification.

Cholelithiasis↗
PubMed1991

Self-expandable stainless steel endoprostheses for treatment of malignant bile duct obstruction.

The Wallstent biliary endoprosthesis is a mesh of stainless steel that is delivered percutaneously over a 7-French catheter but expands to achieve a 1-cm lumen when released across a bile-duct stricture. The small transhepatic track required makes insertion easier, less painful, and probably safer when compared with plastic stents, and the large internal lumen reduces the rate of occlusion by encrusted bile. Wallstent endoprostheses were inserted under local anesthesia in 41 consecutive patients with malignant obstructive jaundice. Biliary drainage was considered the treatment of choice in all of these patients. The diagnosis was based on biopsy results in 32 patients and on radiologic appearances in nine. The patients were followed up in outpatient clinics for 16 months and had repeated radiologic examinations only if they had symptoms suggesting stent occlusion. No cases of hemobilia due to damaged hepatic vessels occurred. Two patients had septicemia treated with antibiotics. Three patients had recurrent jaundice due to growth of tumor below or above the stents. Endoprosthesis migration was not seen. No cases of stent occlusion due to encrustation of bile occurred. The median survival of patients was 105 days (range, 10-545 days). Our experience shows that Wallstent endoprostheses can be inserted with little discomfort for the patient and with relatively few complications. They provide good palliation in patients with malignant obstructive jaundice.

Adult↗
PubMed1988

Combined endoscopic and percutaneous stent insertion to overcome a problem of percutaneous stent insertion.

Non-operative stent insertion is a well-accepted means of palliating malignant biliary obstruction. The endoscopic approach is often considered the procedure of choice, with the percutaneous technique reserved for endoscopy failures. We recently encountered a patient in whom both techniques proved unsuccessful initially, and in whom palliation was finally achieved by means of a combined endoscopic and percutaneous transhepatic procedure.

Aged↗
PubMed1988

Bypass of obstructing bile duct calculus by an endoprosthesis inserted via a T-tube track.

A surgically introduced biliary endoprosthesis in a patient with a cholangiocarcinoma prevented extraction of a calculus in the lower common bile duct through a T-tube track. The problem was solved by the introduction of a second endoprosthesis across the ampulla of Vater through the T-tube track in order to prevent obstruction of the common bile duct by the calculus.

Adenoma, Bile Duct↗
PubMed1988

Percutaneous transhepatic endoprostheses for hilar cholangiocarcinoma.

In patients with unresectable hilar cholangiocarcinoma, percutaneous transhepatic endoprosthesis insertion is one of the available methods of palliation. We reviewed our experience with it in 35 consecutive patients with hilar cholangiocarcinoma who were judged on clinical or radiologic evidence to be unsuitable for resective or palliative surgery. The 30-day mortality rate was 14 percent (5 of 35 patients). Of the remaining 30 patients, endoprosthesis placement was successful in 28, with 2 patients discharged with a permanent external drainage catheter. Twenty-four patients survived a median of 3 months (range 1 to 17 months), and 2 were lost to follow-up. Good or fair palliation of symptoms was achieved in 50 percent of the discharged patients and in 66 percent of those living longer than 3 months. We believe that percutaneous transhepatic endoprostheses can provide useful palliation in patients with hilar cholangiocarcinoma, even in the presence of advanced disease.

Adenoma, Bile Duct↗
PubMed1988

A wearable multichannel tactile display of voice fundamental frequency.

This paper describes a wearable sensory aid that provides the deaf with tactually encoded information about intonation. Fundamental frequency is represented as both place and rate of vibration in a linear array of solenoids. Pitch extraction is accomplished through low-pass filtering and peak detection. A microcomputer is used to measure pitch period, which in turn determines which of the solenoids is actuated. By comparing consecutive periods, the system discriminates against random, noise-related inputs. The device is switchable between 1-, 8-, and 16-channel operation. The electronics package is contained in a case that may be worn on a belt. The solenoid array is worn on the forearm. The system is powered by five, rechargeable lithium cells and runs for at least 6 hours between charges. Proposed developments include the incorporation of digital pitch extraction methods and the option to use the spatial output dimension to encode speech parameters other than fundamental frequency.

Deafness↗
PubMed1986

Bile duct obstruction: radiologic evaluation of level, cause, and tumor resectability.

In a prospective study of 65 patients with bile duct obstruction, various radiologic modalities were compared for their capability to demonstrate the level and cause of obstruction and to indicate accurately tumor resectability. Ultrasound (US) was performed in 65 patients, computed tomography (CT) in 51, direct cholangiography (DC) in 57, and angiography in 35. The level of obstruction was correctly indicated by US in 95% of patients and by CT in 90%, and the cause was correctly indicated by US in 88%, by CT in 63%, and by DC in 89%. In predicting tumor resectability, US was correct in 71% of patients, compared with 42% for CT, 58% for DC, and 25% for angiography. US therefore appears to be the single most useful modality in the evaluation bile duct obstruction.

Bile Duct Neoplasms↗