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Biomedical subjects

J Chong

Publications and source records attributed to J Chong.

At least 37 records · Page 2Linked to original sources
PubMed1994

Small bowel push-type fiberoptic enteroscopy for patients with occult gastrointestinal bleeding or suspected small bowel pathology.

OBJECTIVES: Endoscopic investigation of the small intestine remains the last frontier for gastroendoscopists. We evaluated the diagnostic efficacy and safety of two different push-type, fiberoptic enteroscopes in the investigation of patients with occult gastrointestinal bleeding or suspected small bowel pathology. METHODS: Sixty-six patients (28 men, 38 women; mean age, 68) underwent push-type enteroscopy with either the SIF 10.5L (n = 17; scope length, 2495 mm) or the SIF 3000 (n = 49; length, 2995 mm) enteroscopes (Olympus America, Inc., Lake Success, New York). All patients enrolled had an indication of either occult gastrointestinal bleeding (n = 55) or suspected small bowel pathology (n = 11). Push-type enteroscopy was performed with an overtube and fluoroscopic guidance to better estimate the degree of insertion. Assessments of mucosal visualization, tip deflection, procedure tolerance, and complications were noted. RESULTS: Visualization of the small bowel mucosa and tip deflection was rated excellent in all patients. The mean length of insertion past the ligament of Treitz for the SIF 10.5L was 90 cm and 113 cm for the SIF 3000. Only one complication, a pharyngeal tear, occurred with the SIF 3000. Lesions that may explain the occult GI bleeding were found in 35 out of 55 patients (64%). Twenty-one of these 35 patients (60%) had lesions proximal to the ligament of Treitz, and 14 patients (40%) had lesions distal to the ligament of Treitz. If only distal lesions were considered, the diagnostic yield was 25% (14/55) for occult GI bleeding and 73% (8/11) for suspected small bowel pathology. The most common lesions were arteriovenous malformations (34%), which were successfully cauterized. CONCLUSION: With a relatively high diagnostic yield and therapeutic capability, push-type enteroscopy should play an important role in the investigation and treatment of lesions causing occult GI bleeding and small bowel pathology.

Adult↗
PubMed1994

Epstein-Barr virus-associated gastric carcinoma and Epstein-Barr virus infection of the stomach.

BACKGROUND: Epstein-Barr virus (EBV) has been found to be associated with a type of gastric carcinoma (EBVaGC). However, many questions remain unanswered, such as epidemiology, and pathologic features of EBVaGC and the significance of EBV in the genesis of EBVaGC. EXPERIMENTAL DESIGN: Gastric carcinoma and non-neoplastic mucosa were evaluated to reveal the following issues: the incidence of EBVaGC in Japanese population, pathologic features and EBV genotype, clonality, and gene-expression in EBVaGC, localization of EBV in non-neoplastic stomach, and serum titer of anti-EBV antibodies in EBVaGC-carrying patients. RESULTS: Using PCR and EBER1 in situ hybridization, EBVaGC (definitely amplifiable EBV-DNA and positive EBER1-signal in the nuclei of carcinoma cells) was found in 8 of 72 gastric carcinomas (11%). The dominant genotype of EBV was type A (7/8), with type C (6/8), and F (8/8) restriction enzyme polymorphism, which are the predominant type of EBV found in throat washing of the general population in Japan. EBVaGC was found in the cardia (4/8) or body (4/8) of the stomach, and consisted of 7 advanced and 1 intramucosal carcinoma. By Southern blot analysis of EBVaGC hybridized with right- and left-side probe adjacent to the terminal repeats, EBV was present in a monoclonal episomal form in all of the EBVaGC. EBVaGC lacked expression of EBNA2 (0/8) and LMP1 (0/8) by immunocytochemistry. In non-neoplastic mucosa, EBER1 signal was identified in the infiltrating lymphocytes and shedding epithelial cells predominantly in fundic gland mucosa of patients with EBVaGC (8/8). Patients with EBVaGC showed high titers of anti-VCA IgG (8/8), anti-VCA IgA (2/8) and anti-EA IgG (7/8) antibodies just before surgery. CONCLUSIONS: EBV may infect the surface epithelium of the stomach through the reactivated EBV-carrying lymphocytes. EBV may be a factor initiating EBVaGC. Anti-EBV antibodies or EBER1 in situ hybridization may help to identify patients at high risk for EBVaGC.

Antibodies, Viral↗
PubMed1992

Emulsion stability in a total nutrient admixture for total parenteral nutrition.

A total parenteral nutrition solution containing lipid was tested up to 28 days at 4 degrees C followed by an additional 2 days at 22 degrees C (room temperature) for stability of the emulsion. The total nutrient admixture (TNA) contained 1000 ml 10% FreAmine, 1000 ml 50% dextrose, 500 ml 10% Soyacal, electrolytes, vitamins and trace elements. Stability was determined by direct observation, light and electron microscopy, Coulter counter, pH, osmolality, and fatty acid profile. Samples were tested when fresh at 0 hours, after 2 days at 22 degrees C, 14 days at 4 degrees followed by 2 days at 22 degrees C, and 28 days at 4 degrees C followed by 1 and 2 days at 22 degrees C. Light microscopy measured particles greater than 2 microns in diameter; 99% of these particles were less than 6 microns, with no increase with time. Electron microscopy found that lipid particle size increased slightly up to 30 days, at which time the mean diameter was 0.36 +/- 0.01 micron. Coulter counter studies found that lipid droplet diameter increased while at 22 degrees C; however, on day 30, 99% of the particles were less than 1.97 microns. Mean pH and osmolality were 6.35 +/- 0.04 and 1880 +/- 14.5 mOsm/kg, respectively, with no change over time. Analysis of fatty acids by gas chromatography showed that fatty acid profiles and amounts of triglyceride, phospholipid and total lipid did not change. Thus, the emulsion in the TNA was stable for 28 days refrigeration, followed by 2 days at room temperature.

Drug Stability↗
PubMed1992

Immunohistochemical and histopathologic correlates of Alzheimer's disease-associated Alz-50 immunoreactivity quantified in homogenates of cerebral tissue.

Alz-50 is a monoclonal antibody that immunoreacts with neurofibrillary tangles and neurites in brains with Alzheimer's disease (AD). In addition, the levels of Alz-50 immunoreactivity in brain, measured by either enzyme-linked immunosorbent assay or ALZ-enzyme-linked immunosorbant assay (EIA), are increased in AD relative to age-matched controls. The current study compares the distribution and extent of Alz-50 immunostaining with quantified levels of Alz-50 immunoreactivity measured in adjacent frozen blocks of tissue by ALZ-EIA. The brain tissue studied was obtained from individuals with AD, AD + Down's syndrome (AD + DN), Parkinson's disease with dementia (PD), or AD + PD, and from nondemented aged controls. In AD, AD + DN, and AD + PD, there were significantly higher densities of Alz-50-immunoreactive (AFI) neurons, more abundant diffuse AFI neurites, and higher ALZ-EIA values than in aged controls. In PD, the overall mean density of AFI neurons was significantly lower than in AD and AD + DN, but AFI neurites were as abundant as they were in brains with an AD diagnosis. However, PD was readily distinguished from AD and AD + DN by significantly lower mean ALZ-EIA values, and significantly lower densities of neurofilament-immuno-reactive AD lesions. Multiple-regression analysis demonstrated significant correlations between ALZ-EIA levels and the severity of AD lesions, and the density of AFI neurites, but not with the density of AFI neurons. Therefore, ALZ-EIA levels may represent only a portion of the Alz-50 immunoreactivity detectable by immunohistochemical staining.

Alzheimer Disease↗
PubMed1990

Paediatric acquired immunodeficiency syndrome (PAIDS) in Trinidad and Tobago.

The first twenty-one cases of Paediatric Acquired Immunodeficiency Syndrome (PAIDS) in Trinidad and Tobago were studied. An overwhelming majority of patients were of African descent. Most of the children presented within the first year of life, the average time between presentation and death was 4 1/2 months, and the majority presented with either diarrhoea or pneumonia or failure to thrive, common conditions in the West Indies. Fever lasting longer than two weeks as well as hepatomegaly were clues which led to a definitive diagnosis.

AIDS Serodiagnosis↗
PubMed1989

Gold-conjugated arabinogalactan-protein and other lectins as ultrastructural probes for the wheat/stem rust complex.

Arabinogalactan-protein (AGP, "beta-lectin") was isolated from leek seeds, tested for specificity, conjugated with gold colloids, and used as a cytochemical probe to detect beta-linked bound sugars in ultrathin sections of wheat leaves infected with a compatible race of stem rust fungus. Similar sections were probed with other gold-labeled lectins to detect specific sugars. AGP-gold detected beta-glycosyl in all fungal walls and in the extrahaustorial matrix. Other lectin gold conjugates localized galactose in all fungal walls except in walls of the haustorial body. Limulus polyphemus lectin bound only to the outermost layer of intercellular hyphal walls of the fungus. Binding of these lectins was inhibited by their appropriate haptens and was diminished or abolished in specimens pretreated with protease, indicating that the target substances in the tissue were proteinaceous or that polysaccharides possessing affinity to the lectin probes had been removed by the enzyme from a proteinaceous matrix by passive escape. Binding of Lotus tetragonolobus lectin was limited to the two outermost fungal wall layers but was not hapten-inhibitable. Limax flavus lectin, specific for sialic acids, had no affinity to any structure in the sections. In the fungus, the most complex structure was the outermost wall layer of intercellular hyphal cells; it had affinity to all lectins tried so far, except to Limax flavus lectin and to wheat germ lectin included in an earlier study. In the host, AGP and the galactose-specific lectins bound to the inner domain of the wall in areas not in contact with the fungus. At host cell penetration sites, affinity to these lectins often extended throughout the host wall, confirming that it is modified at these sites. Pre-treatment with protease had no effect on lectin binding to the host wall. After protease treatment, host starch granules retained affinity to galactose-specific lectins, but lost affinity for AGP.

Carbohydrate Metabolism↗
PubMed1989

Pharmacologic intervention in prehospital care: a critical appraisal.

In more than 15 years of paramedic operation, fewer than 15 prehospital studies have been undertaken on the pharmacologic intervention by paramedics. Many of these studies suffer from inadequate sample size or deficient study design. There is no evidence that any medication given by the prehospital care provider is beneficial or cannot safely be delayed until arrival at hospital. Multicenter trials must be designed and implemented if we are to provide the evidence necessary to evaluate our current practice.

Arrhythmias, Cardiac↗
PubMed1989

Visual accommodation and target detection in the vicinity of a window post.

The visual environment of a driver in a car or a pilot in an airplane has intervening objects from the vehicle such as A-pillar posts between the windscreen and the doors in the car or cockpit pillars in the airplane. The presence of such objects can bias the observer's visual accommodation response because of the Mandelbaum effect (e.g., Owens, 1979). When subjects were allowed to focus toward a distance by looking through a large aperture in an intervening post, the detection (monocular) of a briefly presented distant target was found to be significantly better than when no aperture was present. When the size of the aperture was decreased from 2.3 to 1.15 deg diameter, target detection performance was significantly decreased and remained constant as further reduction of foveal cues was made. Although the detection results were generally in agreement with the visual accommodation results, detection accuracy changed significantly only with marked changes in accommodation. In addition to an accommodation bias, interference to target detection was also observed for those targets occurring at a laterally proximal position to the intervening object.

Accommodation, Ocular↗
PubMed1988

A clinician's guide for conducting randomized trials in individual patients.

In determining optimal treatment for a patient conventional trials of therapy are susceptible to bias. Large-scale randomized trials can provide only a partial guide and have not been or cannot be carried out for most clinical disorders. However, randomized controlled trials (RCTs) in individual patients (N of 1 RCTs) may in some circumstances provide a solution to this dilemma. In an N of 1 RCT a patient undergoes pairs of treatment periods (one period of each pair with the active drug and one with matched placebo, assigned at random); both the patient and the clinician are blind to allocation, and treatment targets are monitored. N of 1 RCTs are useful for chronic, stable conditions for which the proposed treatment, which has a rapid onset of action and ceases to act soon after it is discontinued, has shown promise in an open trial of therapy. The monitoring of treatment targets usually includes quantitative measurement of the patient's symptoms with the use of simple patient diaries or questionnaires. Pairs of treatment periods are continued until effectiveness is proved or refuted. The cooperation of a pharmacy is required for the preparation of matching placebos and conduct of the trial. Formal statistical analysis may be helpful for interpreting the results. The practical approach presented in this paper allows clinicians to conduct their own N of 1 RCTs.

Clinical Trials as Topic↗
PubMed1988

Aesthesiometric threshold changes over the course of a workshift in miners exposed to hand-arm vibration.

The objective of this study was to investigate whether aesthesiometric threshold changes occur over the course of a workshift in vibration exposed hard rock miners relative to workers unexposed to vibration during the shift. The subjects were 99 miners and 40 smelter workers; four subjects declined to participate and nine were excluded from the analysis because of apparent failure to comprehend the testing procedure. Two point discrimination and depth sense aesthesiometry were conducted at the beginning and at the end of the workshift in all digits of both hands excluding the thumbs. In addition to the use of a vibrating tool during the shift, age, digital temperature, signs of arm injury, presence of fingertip callus, and handedness were documented. In the analysis the difference between postshift and preshift readings was studied in relation to these variables, particularly exposure to the jackleg drill during the shift. With the exception of exposure of the jackleg drill, no associations were observed between these variables and change over the workshift in aesthesiometric results, on both unadjusted comparison of means and backward elimination regression analysis. A statistically significant association, however, was found between the use of a jackleg drill and change in two point discrimination and in depth sense aesthesiometric results over the course of the shift, for the right hand. Evidence of the occurrence of a learning effect, particularly for two point discrimination aesthesiometry, was observed. The occurrence of an effect in the right, but not the left, hand reflects dominant handedness and relatively greater vibration exposure in the right hand in our subjects. This study supports the incorporation of an exposure free interval before aesthesiometric testing of vibration exposed workers.

Fingers↗
PubMed1986

Determining optimal therapy--randomized trials in individual patients.

Although the treatment of an individual patient in routine clinical practice has been likened to an experiment, the method is so susceptible to bias that we have come to demand multi-patient, double-blind, randomized controlled trials on matters of efficacy. Unfortunately, such trials have not or cannot be carried out for many clinical disorders; even when they have been executed their results may be difficult to extrapolate to individual patients. To resolve this problem, we have begun to use double-blind randomized trials in which a single patient undergoes a series of pairs of treatments, consisting of one active and one placebo or alternative treatment per pair, with the order determined by random allocation. Appropriate treatment targets (signs, symptoms, or laboratory tests) are used as the measure of efficacy, and the trial is continued until efficacy is established or disproved. We describe such a trial, which resulted in a dramatically beneficial modification of treatment in a patient with partially reversible airflow limitation. We have established a clinical service that facilitates the widespread use of the method in our community.

Aged↗
PubMed1985

Effect of ethanol on lecithin:cholesterol acyltransferase (LCAT) activity.

The effect of variable doses of ethanol on plasma lecithin: cholesterol acyltransferase (LCAT) activity was examined in male, atherosclerosis-susceptible squirrel monkeys over a 12-month period. Primates were divided into three groups: 1) Controls fed isocaloric liquid diet; 2) Low Ethanol monkeys given liquid diet with vodka substituted isocalorically for carbohydrate at 12% of calories; and 3) High Ethanol animals fed diet plus vodka at 24% of calories. There were no significant differences between the treatments in serum glutamate oxaloacetate transaminase (SGOT), a measure of liver function. However, plasma LCAT activity (% esterification/min) measured in vitro was significantly reduced in High Ethanol monkeys while cholesterol esterification was elevated in the Low Ethanol group and intermediate in Controls. Similarly, the in vivo appearance of radiolabeled cholesteryl ester in high density lipoproteins (HDL) following the intravenous injection of 3H mevalonolactone was highest in the Low Ethanol primates, intermediate in Controls and significantly lower in monkeys fed the high alcohol diet. In vitro measurement of LCAT enzyme efficiency was similar for the three groups while substrate efficiency was lower in the High Ethanol treatment. Although LCAT activator (apoprotein A-I) was not markedly altered by dietary ethanol and the concentration of LCAT substrates (HDL free cholesterol and phosphatidyl choline) was significantly elevated in the High Ethanol group, subtle modifications in substrate-product composition may account for the observed reduction in cholesterol esterification. These include potential substrate and/or product LCAT inhibition resulting from increased concentrations of plasma free cholesterol, HDL lysophosphatidyl choline, and higher HDL2/HDL3 subfraction ratios, as well as alterations in HDL phospholipid fatty acid profiles in the High Ethanol group. Results from this study provide the first evidence of an anomalous enhancement in LCAT activity in nonhuman primates fed ethanol at 12% of calories and a marked depression in cholesterol esterification at the 24% dose which may be due to substrate alterations and product inhibition prior to overt biochemical evidence of liver dysfunction.

Animals↗
PubMed1976

The ultrastructure of the Spilocaea state of Venturia inaequalis in vivo.

There are indications that the fungus enzymatically degrades the cuticle and epidermal cell wall. The epidermal cells and to a lesser degree the palisade mesophyll cells beneath a sporulating lesion (susceptible reaction) are killed or seriously disrupted. Various stages of conidiogenesis, including development of the pprimary conidium, were observed. A conidium is delimited by a two-layered transverse septum. Before condium secession, a new two-layered inner wall is laid down around the entire conidiogenous cell adjacent to the plasmalemma. The apical region of the new inner wall proliferates beyond the annellation scar left by the seceded conidium and eventually produces another conidium.

Ascomycota↗