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Biomedical subjects

L Chan

Publications and source records attributed to L Chan.

At least 253 records · Page 14Linked to original sources
PubMed1994

Human very-low-density lipoprotein receptor complementary DNA and deduced amino acid sequence and localization of its gene (VLDLR) to chromosome band 9p24 by fluorescence in situ hybridization.

A complementary DNA for the very-low-density lipoprotein receptor (VLDLR) that codes for a protein of 873 amino acids was cloned from a human heart cDNA library. The mature protein of 846 amino acids, preceded by a 27-residue signal peptide, shares 97% amino acid sequence identity with the rabbit VLDLR. Like the low-density lipoprotein receptor, the VLDLR contains five different domains, all of which are highly conserved between human and rabbit. A tetrapeptide NPVY that potentially serves as a signal for clustering of the VLDLR on coated pits is present in the cytoplasmic domain, which is 100% conserved between human and rabbit. We localized the VLDLR gene to chromosome 9p24 by fluorescence in situ hybridization using the cloned cDNA as hybridization probe. The high amino acid sequence homology of the VLDLR between two mammalian species suggests that the receptor plays a fundamental role in lipoprotein metabolism and that energy metabolism mediated by triglyceride utilization may be an evolutionarily highly conserved mechanism.

Amino Acid Sequence↗
PubMed1994

Regulation of apo B mRNA expression in liver and intestine during liver regeneration induced by CCl4.

Acute liver damage in CCl4-treated rats is accompanied by a decrease of the lipoprotein particles HDL and VLDL. However, once the regenerative process has occurred both lipoproteins increase to values higher than control. In this study we have further analyzed the molecular mechanism involved in the induction of the hyperlipidemia during liver regeneration in rats treated with CCl4. The expression of apolipoprotein (apo) B gene at the apo B mRNA editing level has been analyzed during the regenerative process of the liver. The percent of apo B-48 and apo B-100 mRNA was determined and compared to the plasma levels of LDL and VLDL. These results confirm the existence of two different hyperlipidemic stages during liver regeneration. Total apo B mRNA is increased in liver and intestine during both hyperlipidemic stages. The ratio of apo B-100/apo B-48 mRNA remains constant during the first hyperlipidemic stage but the serum levels of VLDL are decreased. Then once the regenerative process has occurred, the steady-state levels of total apo B mRNA remaining, increased with higher amounts of apo B-100 than apo B-48. At this experimental time point the high levels of total apo B mRNA correlate with serum levels of VLDL that are significantly higher than control. These results indicate that apo B gene expression is induced at the mRNA level in liver and intestine during liver regeneration affecting the apo B mRNA editing mechanism in a complex manner and suggest further regulation at the translational or post-translational level.

Animals↗
PubMed1994

Secondary arterioenteric fistula involving the sigmoid colon.

An arterioenteric fistula is a life-threatening condition. Whereas most arterioenteric fistulae involve the duodenum, they can occur at any point along the gastrointestinal tract, and those to the lower tract may present with less classic symptoms than arterioduodenal fistulae. It is likely that more patients with arterioenteric fistulae will present to the emergency department (ED) in the future because of an increasing number of elective aortic aneurysm repairs in an aging population. We present a patient with a secondary fistula involving the sigmoid colon who presented to the ED with abdominal pain and a tender abdominal mass.

Aged↗
PubMed1994

A shortened dengue IgM capture ELISA using simultaneous incubation of antigen and peroxidase-labeled monoclonal antibody.

A shortened IgM capture ELISA for the detection of dengue IgM antibodies using simultaneous incubation of antigen and peroxidase-labeled monoclonal antibody was described. The shortened two-step assay was compared with the four-step IgM capture ELISA on sera from dengue patients confirmed by the hemagglutination inhibition (HI) test. When paired acute and convalescent sera were tested, the shortened ELISA showed 100% agreement with HI results. It detected dengue IgM antibodies in the acute sera of 66% of patients with a primary dengue infection, 60% of patients with a secondary infection, and 98% of patients with a presumptive secondary infection. When the results of 151 dengue patients were combined, 75% of the acute sera were positive by the shortened IgM capture ELISA.

Journal Article↗
PubMed1994

The effect of spinal immobilization on healthy volunteers.

STUDY OBJECTIVE: To determine the effects of standard spinal immobilization on a group of healthy volunteers with respect to induced pain and discomfort. DESIGN: Prospective study. SETTING: University teaching hospital. TYPE OF PARTICIPANTS: Twenty-one healthy volunteers with no history of back disease. INTERVENTIONS: Subjects were placed in standard backboard immobilization for a 30-minute period. Number and severity of immediate and delayed symptoms were determined. MEASUREMENTS AND MAIN RESULTS: One hundred percent of subjects developed pain within the immediate observation period. Occipital headache and sacral, lumbar, and mandibular pain were the most frequent symptoms. Fifty-five percent of subjects graded their symptoms as moderate to severe. Twenty-nine percent of subjects developed additional symptoms over the next 48 hours. CONCLUSION: Standard spinal immobilization may be a cause of pain in an otherwise healthy subject.

Adolescent↗
PubMed1994

Cervical fracture as the initial presentation of multiple myeloma.

Cervical-spine injury may occur in elderly patients with a history of minor trauma. We present the case of a patient who suffered a pathologic cervical-spine fracture as the initial presentation of multiple myeloma. A review of the medical conditions that predispose the elderly to cervical-spine fracture in the absence of major trauma is presented.

Cervical Vertebrae↗
PubMed1994

A comparison of drug interaction software programs: applicability to the emergency department.

STUDY OBJECTIVE: To compare the features of available drug interaction software programs in terms of general applicability to an emergency department setting. DESIGN: Prospective evaluation of drug interaction software programs based on presence or absence of a variety of performance features. SETTING: University and community hospital EDs. PARTICIPANTS: Eight commercially available drug interaction software programs. RESULTS: Programs were evaluated according to designated performance and data base features. Tabulated results were compiled for purposes of comparison. CONCLUSION: Although no computer program tested completely met the specific needs of a busy ED, many programs have features with at least some general applicability.

Drug Information Services↗
PubMed1994

Chronic renal transplant rejection.

The most common cause of renal allograft failure, after the first year posttransplant, is chronic rejection (CR). The impact on allograft loss of CR has remained constant despite the improvements in immunosuppression that have occurred. This process is characterized by a gradual decline in graft function over months to years. Proliferation of vascular smooth muscle cells and fibrosis of the large arteries are the main pathologic characteristics of CR. The clinical course varies widely among patients, from stable function for years to graft failure within several months. The precipitating factors of CR may be many and are unknown. Chronic rejection is likely to be, at least in part, immune mediated. A history of acute rejection episodes correlates strongly with the development of CR. No method has been clearly shown to prevent or treat CR.

Adult↗
PubMed1994

Increased nephron oxygen consumption: potential role in progression of chronic renal disease.

We have previously reported that remnant kidneys demonstrate marked increases in oxygen consumption (QO2) when normalized for sodium transport as compared with normal kidneys. This increase in oxygen consumption could be attenuated by dietary maneuvers such as protein restriction and phosphate restriction and also by calcium channel blockers. The basis of this enhanced metabolic activity, however, has not been fully defined. Furthermore, circumstances of increased oxygen consumption are associated with enhanced oxygen radical generation. These oxygen radicals could lead to renal tissue lipid peroxidation if the remnant kidney contains insufficient oxygen radical scavengers. This review summarizes available evidence for increased nephron oxygen consumption as a cause of tubulointerstitial injury and its relationship to progression of chronic renal disease.

Animals↗
PubMed1994

Genetic relatedness as a determinant of predisposition to Ascaris lumbricoides and Trichuris trichiura infection.

The present study examines the role of host genetics in predisposition to Ascaris lumbricoides and Trichuris trichiura infection, by comparing the associations between age-standardized infection intensities of parents and their children (genetically related), with age-standardized infection intensities of parents alone (not related), within families previously demonstrated to exhibit familial predisposition. The lack of a consistent trend in infection intensity associations within families, in particular the lack of a stronger association between parents and their children than between unrelated parents, suggests that host genetic factors are not a major determinant of infection status. If there is a genetic basis for predisposition, then the data suggest that the effects of this genetic basis are overwhelmed by other, environmental or behavioural features of the family household.

Adolescent↗
PubMed1994

Experience with lower urinary tract disruptions associated with pelvic fractures: implications for emergency room management.

A retrospective review of prospectively gathered data from 249 trauma patients was undertaken to study the association of lower urinary tract disruptions with pelvic fractures and to confirm guidelines for the initial investigation and management of such patients in the emergency room. Of 249 patients with pelvic fractures, 124 (50%) had haematuria and 17 (7%) had lower urinary tract disruptions (7 urethral ruptures, 9 bladder ruptures and 1 patient with both bladder and urethral ruptures). Gross haematuria or blood at the urethral meatus was noted in 16 of 17 patients with urological injuries. Twenty-five per cent of patients with unstable pelvic fractures had lower urinary tract disruption compared to 6% of patients with stable fractures (P < 0.05). Retrograde urethrography followed by cystography is indicated in all cases of pelvic fractures with blood at the urethral meatus, macroscopic haematuria or associated signs such as inability to void and perineal haematoma. Urinary diversion alone was used in partial urethral ruptures while surgical exploration and repair were performed in complete urethral ruptures and in most cases of bladder ruptures.

Adolescent↗
PubMed1994

Effect of an endothelin-receptor antagonist on ischemic acute renal failure.

In the isolated perfused rat kidney, endothelin (ET) added to the perfusate at concentrations ranging from 50 to 500 pmol/l resulted in a dose-dependent reduction in renal perfusate flow (RPF) and inulin clearance (CIn). The decrease in RPF (17 +/- 3 vs. 34 +/- 3 ml.min-1 x g-1; P < 0.01 compared with control) and CIn (89 +/- 13 vs. 317 +/- 19 microliters.min-1 x g-1; P < 0.01 compared with control) by ET (500 pmol/l) was prevented by the ET antagonist BQ-123 (10 microM), with full recovery of RPF [36 +/- 2 vs. 34 +/- 3 ml.min-1 x g-1; not significant (NS) compared with control] and CIn (299 +/- 51 vs. 317 +/- 19 microliters.min-1 x g-1; NS compared with control). In the absence of ET, perfusion of the kidney with a similar concentration of BQ-123 (10 microM) did not induce any changes in RPF (36 +/- 5 vs. 34 +/- 3 ml.min-1 x g-1; NS compared with control) or CIn (320 +/- 14 vs. 317 +/- 19 microliters.min-1 x g-1; NS compared with control). After 60 min of arterial clamping, BQ-123 (10 microM) given before the onset of ischemia and during reflow improved CIn (88 +/- 4 vs. 19 +/- 3 microliters.min-1 x g-1; n = 6, P < 0.01) and net tubular sodium reabsorption (TNa) compared with no treatment. On the other hand, the same dose (10 microM) of BQ-123 given only during the reperfusion period was not effective in preventing the decreases in either CIn or TNa.(ABSTRACT TRUNCATED AT 250 WORDS)

Absorption↗
PubMed1994

Getting the most out of low-dose syringe prefilling of a high-cost biotechnology agent.

The recent increased usage of high-cost biotechnology agents has placed a tremendous impact on the hospital pharmacy budget. One approach in improving cost containment is to minimize waste during the preparation of these agents. This is particularly practical and possible in the process of low-dose syringe repackaging of Sargramostim (GM-CSF) used for the treatment of neutropenia. In search of ways to reduce waste, this study looked into the dos and don'ts of repackaging this agent in syringes. Decreased waste is very significant if GM-CSF is properly reconstituted with bacteriostatic water for injection and if a syringe equipped with a permanently attached needle is used. Another 10% of the solution from each vial could be saved if the solution is withdrawn with a technique involving the vial in a right-side-up position.

Biotechnology↗
PubMed1994

Evaluation of the bacteriological contamination of a closed feeding system for enteral nutrition.

A closed enteral delivery system consisting of a cardboard tetrapack containing the sterile ready-to-use liquid feed and an independent sterile administration set, has been devised. We found bacterial contamination within 24 hours in this system in patients on ventilatory support in intensive care. This emphasises the need for meticulous care in handling enteral feeding systems to prevent environmental contamination.

Asepsis↗
PubMed1994

Apolipoprotein B synthesis: a square lattice model.

We have formulated a random walk model for emerging apolipoprotein B interaction with its translocation channel on the surface of the rough endoplasmic reticulum based on the assumption that this interaction is a diffusion-mediated process. From this model, we found that a substantial proportion of mRNA-ribosome complexes was not bound to their translocation channels at any given moment of quasi-steady state. The duration of polypeptide chain elongation was an important determinant of the number of mRNA-ribosome complexes bound to their channels, but it had little net effect on the integrated rate of protein synthesis and translocation. The rates of protein synthesis and translocation for different secretory proteins that were cotranslationally translocated were very similar provided that they had similar mRNA concentration. We conclude that one of the control mechanisms regulating apolipoprotein B production may rely on the properties of translocation channels to determine the fate of newly synthesized apolipoprotein B molecules.

Animals↗