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Biomedical subjects

S Cheng

Publications and source records attributed to S Cheng.

At least 163 records · Page 9Linked to original sources
PubMed1997

Prospective randomized comparative study of bipolar electrocoagulation versus heater probe for treatment of chronically bleeding internal hemorrhoids.

BACKGROUND: Our purpose was to compare the efficacy, complications, failure rates, and crossovers of heater and bipolar probe treatments of chronically bleeding internal hemorrhoids. METHODS: Eighty-one patients (31 female, 50 male) with mean age of 53 years had large (grade 2 to 3) internal hemorrhoids with bleeding for a mean of 12 years, had failed medical management, and were randomized in a prospective study of anoscopic treatments to heater versus bipolar probes. Failure was defined as a major complication or failure to reduce the size of all internal hemorrhoids with three or more treatments. RESULTS: With similar background variables and no difference in treatment times, rectal bleeding and other symptoms were controlled in a shorter time with the heater probe than with the bipolar probe (77 versus 121 days). Five complications (fissures, bleeding, or rectal spasm) occurred with the bipolar probe, and two occurred with the heater probe. The heater probe caused more pain during treatments but had significantly fewer failures and crossovers. CONCLUSIONS: For patients who had failed medical management of chronically bleeding internal hemorrhoids, the techniques and complications of heater and bipolar probes were similar, but pain was more common, failures and crossovers were less frequent, and the time to symptom relief was shorter with the heater probe than with the bipolar probe.

Chronic Disease↗
PubMed1997

An economic analysis of patients with active arterial peptic ulcer hemorrhage treated with endoscopic heater probe, injection sclerosis, or surgery in a prospective, randomized trial.

BACKGROUND: There are no published, detailed assessments of the direct costs of endoscopic hemostasis for actively bleeding peptic ulcers. We compared the direct costs of care for patients with active ulcer hemorrhage treated with endoscopic or medical-surgical therapies and correlated these costs with patient outcomes. METHODS: In a prospective, randomized, controlled trial, 31 patients with active ulcer hemorrhage at emergency endoscopy were randomly assigned to heater probe, injection, or medical-surgical treatment. For further ulcer bleeding, heater probe and injection patients were re-treated endoscopically and medical-surgical patients were referred for surgery. Direct costs were estimated using fixed and variable costs for resources consumed and Medicare reimbursement rates for physician fees. RESULTS: Compared to medical-surgical treatment, the heater probe and injection groups had significantly higher primary hemostasis rates (100% and 90% vs 8%) and lower rates of emergency surgery (0% and 10% vs 75%), blood transfusions, and median direct costs per patient ($4153 and $5247 vs $11,149). Furthermore, compared to medical-surgical treatment, the heater probe group had a significantly lower incidence of severe ulcer rebleeding (11% vs 75%). CONCLUSIONS: Heater probe and injection sclerosis are similarly efficacious treatments for active ulcer hemorrhage, and both treatments yield significantly lower direct costs of medical care and cost savings.

Aged↗
PubMed1997

Resolution of chronic anal fissures after treatment of contiguous internal hemorrhoids with direct current probe.

BACKGROUND PURPOSES: (1) to prospectively evaluate efficacy and safety of direct current (DC) probe treatment of chronic anal fissures associated with internal hemorrhoids, and (2) to estimate direct and indirect costs of anoscopic treatment versus surgery. METHODS: Ten patients with chronic fissures of 11 mm (mean length) had symptoms for 5 months (mean) in spite of medical management; all had internal hemorrhoidal disease. DC coagulation was applied to two or three contiguous internal hemorrhoids per outpatient session. Eleven mA (mean) of DC current was delivered for 7 minutes (mean) per hemorrhoid segment. RESULTS: All 10 patients had relief of chronic anal pain within two treatments and nine anal fissures healed within 4 weeks. One patient developed a perianal abscess and fistula requiring surgery. There were no recurrences in 20 months (mean) of follow-up with medical management. Mean direct and indirect costs (in terms of lost time from work or usual activity) of DC probe treatments were estimated to be 10% to 30% lower and 2 to 10 times less, respectively, than standard surgery for chronic anal fissures. CONCLUSION: DC probe treatment for chronic anal fissures associated with internal hemorrhoidal disease is an important advance as an effective, safe, and cost-effective nonsurgical treatment in selected patients.

Adolescent↗
PubMed1997

A randomized prospective study of endoscopic bipolar electrocoagulation and heater probe treatment of chronic rectal bleeding from radiation telangiectasia.

BACKGROUND: Our purposes were to (1) evaluate efficacy and safety of bipolar or heater probe endoscopic coagulation compared to prior medical therapy for bleeding radiation telangiectasia, and (2) consider the impact of treatments on patients' impression of their overall health and activity. METHODS: Twelve months of medical management had failed in 18 men and 3 women with chronic, recurrent hematochezia and anemia after radiation treatment of pelvic malignancies. Patients had multiple rectal telangiectasias coagulated with bipolar or heater probes in a randomized, prospective study. RESULTS: Rectal bleeding stopped within four treatment sessions. During 12 months of endoscopic versus medical therapy, severe bleeding episodes diminished significantly for bipolar probe versus 12 months of prior medical therapy (75% vs 33%) and heater probe (67% vs 11%); mean hematocrits rose significantly for patients undergoing bipolar (38.2 vs 31.9) and heater probe (37.6 vs 28.4) treatments, and their impression of overall health improved. During long-term follow-up, new telangiectasias or rectal bleeding were easily controlled. No major complications resulted. CONCLUSIONS: (1) Bipolar or heater probes were safe and effective relative to medical therapy for palliation of patients with lower gastrointestinal bleeding from radiation telangiectasias, and (2) all patients improved in ability to travel and exercise and in their overall impression of their health.

Aged↗
PubMed1997

NMR study of solid C60(gamma-cyclodextrin)2.

A solid complex of C60 with gamma-cyclodextrin (gamma-CyD) was examined with NMR spectroscopic methods in order to understand the dynamics of C60, and the interaction between C60 and gamma-CyD. A 13C solid-state cross-polarization magic angle spinning (CP/MAS) NMR spectra shows C60 resonance at 142.6 ppm. This provides the evidence of interaction between 13C spins in C60 and 1H spins in the gamma-CyD host. Ambient temperature experiments on the 13C CP/MAS NMR, with varying contact time, shows that the water associated with gamma-CyDs plays an important role in the nuclear relaxation processes. The dynamics of C60 in gamma-CyD was investigated using temperature and field-dependent 13C spin-lattice relaxation time measurements. The influence of water on the dynamics of C60 was less significant below 250 K.

Carbon↗
PubMed1997

Effect of co-lipids in enhancing cationic lipid-mediated gene transfer in vitro and in vivo.

Complexes of DNA and cationic lipids are promising vectors for gene transfer. Most cationic lipid formulations contain both a cationic component and a neutral co-lipid. We found that the co-lipid could influence DNA uptake in COS-1 cells, but processes subsequent to uptake were even more important in determining gene expression. We compared dioleoylphosphatidylethanolamine (DOPE) and structural analogs of DOPE combined with cationic lipids and found that DNA uptake and transgene expression did not always correlate. Transgene expression was dependent on DNA uptake into the cell, on entry of DNA into the cytoplasm, and on release of DNA from the lipid complex. We found that some co-lipids had a greater effect on DNA uptake, whereas others had a greater effect on steps subsequent to entry. Based on those results, we tested the hypothesis that co-lipids conferring different properties could be combined to enhance gene transfer. The results showed that a combination of co-lipids had a synergistic effect on expression. We also found that structural analogs of DOPE were more effective than DOPE in enhancing gene transfer to mature human airway epithelia studied in vitro and to mouse lung studied in vivo. These data provide insight into the mechanism by which co-lipids influence cationic lipid-mediated gene transfer and show that optimization of the effects of co-lipids can enhance gene transfer both in vitro and in vivo.

Animals↗
PubMed1997

An optical phantom with tissue-like properties in the visible for use in PDT and fluorescence spectroscopy.

The design and characterization of optical phantoms which have the same absorption and scattering characteristics as biological tissues in a broad spectral window (between 400 and 650 nm) are presented. These low-cost phantoms use agarose dissolved in water as the transparent matrix. The latter is loaded with various amounts of silicon dioxide, Intralipid, ink, blood, azide, penicillin, bovine serum, and fluorochromes. The silicon dioxide and Intralipid particles are responsible for the light scattering whereas the ink and blood are the absorbers. The penicillin and the azide are used to ensure the conservation of such phantoms when stored at 4 degrees C. The serum and fluorochromes, such as Coumarin 30, produce an autofluorescence similar to human tissues. Various fluorochromes or photosensitizers can be added to these phantoms to simulate a cancer photodetection procedure. The absorption and fluorescence spectroscopy of the porphyrin-type fluorescent markers used clinically for such photodetection procedures is similar in these phantoms and in live tissues. The mechanical properties of these gelatinous phantoms are also of interest as they can easily be moulded and reshaped with a conventional cutter, so that complex structures and shapes, with different optical properties, can be designed. The optical properties of these phantoms were determined between 400 and 650 nm by measuring their effective attenuation coefficient (mu eff) and total reflectance (Rd). The microscopic absorption and reduced scattering coefficients (mu a, mu s') were deduced from mu eff and Rd using a Monte Carlo simulation.

Animals↗
PubMed1997

Design and construction of a hybrid immunoglobulin domain with properties of both heavy and light chain variable regions.

The complementarity-determining regions (CDRs) of a human kappa light chain were replaced with CDRs from a murine gamma-1 heavy chain and, by use of molecular modeling, key heavy chain framework residues were identified and thus included to preserve the native conformation of the heavy chain CDRs. Co-expression of this hybrid human kappa chain (V[HB]C[L]) with a human kappa chain counterpart (V[L]C[L], engineered to contain murine light chain CDRs) resulted in the secretion of high levels of a heterodimeric protein (V[HB]C[L]::V[L]C[L]) termed 'kappabody'. This protein also had equivalent affinity for antigen as the Fab' of the parent murine IgG1. High-level secretion was also observed for the hybrid chain as homodimers (V[HB]C[L]::V[HB]C[L]), which is not observed for chimeric chains consisting of a heavy chain variable region and light chain constant region, i.e. V[H]C[L] homodimers or single chains are not secreted. This indicates that regions within the variable domain, required for secretion of light chains, reside outside of the hypervariable regions (CDRs) and that the heavy chain CDRs and supporting residues do not prevent secretion. These results demonstrate the possibility of designing small, single-domain molecules possessing a given binding activity which may be secreted at high levels from mammalian cells.

Amino Acid Sequence↗
PubMed1997

A microplate allele-specific oligonucleotide hybridization assay for detection of factor V Leiden.

Factor V Leiden is the most common genetic risk factor for thrombosis. Currently, the determination of factor V Leiden genotype is limited to laboratories with expertise in molecular methods to develop "home brew" assays using polymerase chain reaction (PCR) to amplify genomic DNA, followed by analysis of Mnl I restriction fragments. These methods are not standardized, are labor intensive, and have low throughput. We describe a method for determination of factor V Leiden genotype using allele-specific oligonucleotide capture probes coated onto 96 well plates, requiring only a thermal cycler and a microplate spectrophotometer to perform. With an automated strip washer and plate reader, genotypes could be determined in 80 min from completion of PCR. Within-run and between-run coefficients of variation for the assay were < 10%. In all 160 cases studied, the microplate assay correctly identified the factor V genotype. The microplate oligonucleotide hybridization assay is a simple and reliable system for determination of factor V Leiden genotype. The assay offers an automatable, high-throughput alternative to current testing methodologies.

Alleles↗
PubMed1997

Utility of ultrasound to assess risk of fracture.

Traditional assessments of bone properties have utilized densitometry techniques such as Dual Energy X-ray Absorptiometry (DXA). Recently, quantitative ultrasound (QUS) has been introduced as an alternative method of assessing bone properties. Advantages of QUS over X-ray techniques include low costs, portability, and nonionizing radiation. Proponents of QUS have claimed that this technology can provide information not only about the density but also about the structure and mechanical properties of bone. There are two major questions that need to be answered for those who seek to diagnose bone disorders with ultrasound: (1) what does quantitative ultrasound actually measure, and, even more importantly, (2) what is its clinical utility? In this review we will briefly examine the first question and will focus on the utility of ultrasound in clinical trials to discriminate between fractures and non-fractures and to predict the risk of fractures.

Adult↗
PubMed1997

A PCR assay for identification of Enterococcus faecium.

Enterococcus faecium has recently emerged as a serious nosocomial pathogen. The prevalence and severity of enterococcal infections, the mortality rate from such infections, and the antibiotic resistance of enterococci are often species dependent. Since conventional biochemical methods fail to differentiate E. faecium from certain newly described enterococcal species, a PCR-based assay was developed for the rapid identification of E. faecium.

Enterococcus faecium↗
PubMed1997

An adenovirus-simian immunodeficiency virus env vaccine elicits humoral, cellular, and mucosal immune responses in rhesus macaques and decreases viral burden following vaginal challenge.

Six female rhesus macaques were immunized orally and intranasally at 0 weeks and intratracheally at 12 weeks with an adenovirus type 5 host range mutant (Ad5hr)-simian immunodeficiency virus SIVsm env recombinant and at 24 and 36 weeks with native SIVmac251 gp120 in Syntex adjuvant. Four macaques received the Ad5hr vector and adjuvant alone; two additional controls were naive. In vivo replication of the Ad5hr wild-type and recombinant vectors occurred with detection of Ad5 DNA in stool samples and/or nasal secretions in all macaques and increases in Ad5 neutralizing antibody in 9 of 10 macaques following Ad administrations. SIV-specific neutralizing antibodies appeared after the second recombinant immunization and rose to titers > 10,000 following the second subunit boost. Immunoglobulin G (IgG) and IgA antibodies able to bind gp120 developed in nasal and rectal secretions, and SIV-specific IgGs were also observed in vaginal secretions and saliva. T-cell proliferative responses to SIV gp140 and T-helper epitopes were sporadically detected in all immunized macaques. Following vaginal challenge with SIVmac251, transient or persistent infection resulted in both immunized and control monkeys. The mean viral burden in persistently infected immunized macaques was significantly decreased in the primary infection period compared to that of control macaques. These results establish in vivo use of the Ad5hr vector, which overcomes the host range restriction of human Ads for rhesus macaques, thereby providing a new model for evaluation of Ad-based vaccines. In addition, they show that a vaccine regimen using the Ad5hr-SIV env recombinant and gp120 subunit induces strong humoral, cellular, and mucosal immunity in rhesus macaques. The reduced viral burden achieved solely with an env-based vaccine supports further development of Ad-based vaccines comprising additional viral components for immune therapy and AIDS vaccine development.

Adenoviruses, Human↗
PubMed1997

Calcaneal bone mineral density predicts fracture occurrence: a five-year follow-up study in elderly people.

A 5-year follow-up study investigated calcaneal bone mineral density (BMD) and changes in BMD in relation to fracture occurrence. The subjects comprised two cohorts born in 1914 and 1910 living in the city of Jyväskylä in central Finland. One hundred and three men (82%) and 188 women (73%), aged 75, and 57 men (74%) and 136 women (65%), aged 80, of the eligible population participated in the baseline bone measurements. The follow-up bone measurements were obtained for 59 men (68%) and 119 women (66%), aged 80 years, and for 21 men (53%) and 61 women (48%), aged 85 years. During the follow-up period, 8 men and 36 women from the younger and 11 men and 24 women from the older cohort sustained at least one fracture. When the baseline levels of BMD were related to fracture occurrence, the results clearly showed that with increased BMD values the probability of fracture decreased. Where men and women had similar BMD values, they also had a similar fracture probability. Except for one woman in the older cohort, none of those who had initial BMD values more than 1 standard deviation above the mean for their age developed a fracture during the follow-up period. The mean annual decrease in BMD was greater in the women (2.5-2.7%) than in the men (0.8-1.0%). The BMD change tended to associate with fracture occurrence only in the 75-year-old women (p = 0.075). The results suggest that calcaneus BMD can be used as a predictor of fracture occurrence in 75- to 80-year-old men and women. However, associating fractures with the change in BMD was difficult due to the limited number of survivors and initial differences in BMD values.

Aged↗
PubMed1997

[Construction of mycobacterium tuberculosis genomic library].

OBJECTIVE: To provide effective tools for identification and characterization of M. tuberculosis genes/antigenes and to evaluate their roles in diagnosis, vaccination, drug resistance, and pathogenesis. METHODS: M. tuberculosis genomic DNA obtained from H 37 Ra strain was partially digested with DNase I. The DNA fragments ranging from 4-8 kb were isolated from agarose gel and ligated to EcoR I adaptor, and the products were linked to lamda gt11 arms and packaged using an in vitro packaging extract. The different diluted bacteriophages were used to transfect bacteria Y1090. RESULTS: The efficiency and titer of the library were 85% and 3 x 10(5) pfu/ml, respectively. The library contained 1.3 x 10(5) individual recombinant phage whose foreign DNA inserted fragment size was 3.5 kb on average. CONCLUSION: The genomic DNA library constructed here can provide sufficient clone to cover H37Ra gene.

Genome, Bacterial↗
PubMed1997

[The effects of lidocaine on lymphocyte beta-adrenergic receptor at different pH].

The effects of lidocaine on beta-adrenergic receptor binding and the yield of epinephrine-stimulated cAMP at different pH were measured by radioligand binding assay and radioimmunoassay. The results showed that the binding of H-DHA to the receptor and yield of epinephrine-stimulated cAMP increased with increasing pH (P < 0.001) and lidocaine inhibitory potency also increased with increasing pH (P < 0.001); The results indicate that the response to beta-agonists would increase with pH during cardiopulmonary resuscitation when lidocaine is not present, but it would not increase with pH when lidocaine is present, suggesting that lidocaine may inhibit binding of beta-agonists to receptor by changing lipid fluidity of cell membrane with increasing pH.

Anesthetics, Local↗
PubMed1997

[Preliminary study of anatomic relation among nasopalatine duct, central incisor root and floor of nasal cavity with X-ray measurement].

The authors studied anatomic constructure of anaterior maxilla. They observed the position relationships among nasopalatine duct, central incisor root and floor of nasal cavity through X-ray measurement. The results showed: (1) Average distance between the anterior wall of nasopalatine duct and cortical plate of anterior maxilla was 7.80 +/- 1.43 mm. (2) Average distance between the anterior wall of nasopalatine duct and central incisor root was 4.15 +/- 1.48 mm. (3) Average distance between the tip of central incisor root and floor of nasal cavity was 12.62 +/- 2.47 mm. (4) Average length of the nasopalatine duct was 15.04 +/- 2.20 mm. The results are beneficial of dental implantation and orthognathic surgery.

Adult↗