Search PubMed⌕ Search

Biomedical subjects

L Chow

Publications and source records attributed to L Chow.

66 records · Page 4Linked to original sources
PubMed1981

Detection of serum antibody to herpes simplex virus type I by enzyme-linked immunosorbent assay (ELISA).

For setting up an Enzyme-Linked Immunosorbent Assay (ELISA) to detect antibodies to herpes simplex virus type 1 (HSV-1), the virus was propagated in Vero cells and partially purified by sonification and ultracentrifugation on 30% sucrose solution. DEAE ion-exchange column chromatography was used for purification of goat anti-human IgG serum. The anti-human IgG immune serum and alkaline phosphatase were conjugated by glutaraldehyde method. ELISA test was performed by reacting HSV-1 antigen coated in polystyrene tubes with serum specimens and enzyme-IgG conjugates. The color produced by enzyme-substrate reaction was measured on a spectrophotometer. The results obtained by the ELISA had a good agreement with those obtained by a standard neutralization procedure on 119 serum specimens tested for antibody to HSV-1.

Antibodies, Viral↗
PubMed1981

Acid protease in adult Schistosoma japonicum (Formosan strain).

Acid protease in Schistosoma japonicum (Formosan strain) was found. The isoelectric point of the enzyme was found to be 4.4 and 6.0 by the isoelectrofocusing technique and the molecular weight was estimated to be about 31,000 daltons determined by Sephadex gel filtration. The Km of the enzyme for human globin was found to be 2.9 X 10(-4) M.

Animals↗
PubMed1980

Identification of mosquito blood meals by cellulose acetate and starch gel electrophoresis.

Cellulose acetate (CAE) and starch gel electrophoresis (SGE) were examined for their ability to identify species hemoglobins in mosquito blood meals. Blood meals analyzed serologically by the precipitin (PT) and passive hemagglutination inhibition (PHI) techniques served as standards for comparison. CAE, could not differentiate blood meals from divergent vertebrate hosts (man, rabbits, and mice) solely on the basis of the migratory properties of their respective hemoglobins. However, all could be differentiated when the migratory properties of both their hemoglobins and serum albumins were considered. CAE, like PT, was consistently able to identify blood meals for 18--24 hr post-ingestion. In contrast, PHI was able to identify blood meals for up to 48 hr post-feeding. SGE lacked the sensitivity of CAE, PHI and PT. SGE could only differentiate blood meals for 5--7 hr after ingestion. These results indicate that CAE has potential as a rapid technique for determining the origin of blood meals ingested by arthropod disease vectors.

Aedes↗
PubMed1979

Identification and mapping of the transcriptional and translational products of the yeast plasmid, 2mu circle.

We have identified two major and approximately ten minor poly(A)-containing RNA species in S. cerevisiae which arise from in vivo transcription of the yeast plasmid, known as 2mu circle. The two major species, which are 1325 and 1275 bases in length, are transcribed from the two unique halves of the plasmid and extend into the inverted repeat sequences which separate the unique regions. The map positions of the minor transcripts, which range in length from 350 to 2600 bases, indicate that except for a small region of the genome in which no transcription is observed, both strands of the entire 2mu circle genome are transcribed. We also present evidence demonstrating that RNA transcribed from 2mu circular DNA is used to program the synthesis of specific proteins in yeast: that is, yeast RNA complementary to 2mu circle DNA can be translated in vitro to produce specific polypeptides of substantial size. Finally, the pattern of transcription of 2mu circle suggests the possibility that messenger RNA species are derived by cleavage of larger transcripts, and in addition, that the intramolecular recombination of 2mu circle which occurs in yeast functions as a genetic switch to allow separate expression of two sets of genes on the 2mu circle genome.

Binding Sites↗
PubMed1978

Cholesterol oxidation in primates by simultaneous sterol balance and breath analysis.

Six female adult rhesus monkeys and baboons with exteriorized enterohepatic circulations were simultaneously assessed following [26-14C]cholesterol pulse labeling by 14CO2 breath analysis and combined isotopic and chromatographic sterol balance during metabolic steady state. Bile acid synthesis and/or secretion were compared with 14CO2 breath analysis of cholesterol oxidation during short term physiological changes, and with total bile acid diversion and feedback inhibition, and biliary tract obstruction. Cholesterol oxidation by breath analysis compared closely with acidic sterol losses during steady-state conditions (145.6 +/- 23.9 vs 144.6 +/- 24.4 mg/24 h) and was sensitive enough to detect changes resulting from diurnal variation and fasting. The 14CO2 test detected inhibition of bile acid synthesis consequent to bile acid feedback (355 +/- 32 to 88 +/- 31 mg/24 h, P less than 0.001) or biliary tract obstruction (158 +/- 27 to 60 +/- 28 mg/24 h, P less than 0.05) but underestimated increased synthesis induced by acute bile diversion (245 +/- 24 vs. 868 +/- 104 mg/24 h, P less than 0.01 at 24 h). Insignificant 14C was detected by carcass analysis following cessation of exhaled 14CO2.

Animals↗
PubMed1976

Characterization of a mini-ColC1 plasmid.

An in vitro constructed plasmid, pVH15, consisting of the entire genome of the plasmid ColE1, the tryptophan operon of Escherichia coli, and regions of the bacteriophage PHI80pt190, spontaneously gave rise in E. coli to a mini-ColE1 plasmid consisting of approximately one-half of the ColE1 genome and a small segment of phi80pt190 DNA. This mini-ColE1 plasmid, designated pVH51, has a molecular weight of approximately 2.1 X 10(6) and possesses a single EcoRI restriction site. Heteroduplex analyses showed that about 90% of the pVH51 plasmid hybridizes to about 50% of the ColE1 plasmid. Phenotypically, pVH51 did not produce colicin E1 but conferred immunity to this colicin. The number of mini-ColE1 plasmid molecules per cell was maintained at a four- to fivefold higher level than normal ColE1. A mini-ColE1 hybrid plasmid, designated pML21 and consisting of pVH51 and the kan fragment of plasmid pSC105 inserted at the EcoRI restriction site of mini-ColE1, was maintained at a lower copy number level than pVH51. As in the case of normal ColE1, both pVH51 and pML21 continued to replicate in the presence of chloramphenicol. The promotion of conjugal transfer of pVH51 and pML21 by a self-transmissible plasmid was greatly reduced compared with normal ColE1.

Chloramphenicol↗
PubMed1976

A restriction endonuclease analysis of the bacterial plasmid controlling the ecoRI restriction and modification of DNA.

Genetic analyses of DNA restriction and modification mechanisms have been encumbered by the inability to rigorously select for mutant phenotypes associated with these systems. The application of restriction endonucleases has now proved to be a successful approach to the genetic analyses of small genomes that are recalcitrant to the more standard genetic techniques. Restriction endonucleases EcoRI and HindIII were used to analyze the structure of the plasmid genome responsible for the EcoRI restriction endonuclease and modification methylase. This plasmid in the original clinical isolate of Escherichia coli appears to be identical to the ColE 1 plasmid except for a 1.95 kilobase pair segment which contains these genes. A preliminary restriction map of this plasmid is presented.

Base Sequence↗
PubMedDate not supplied

Power Doppler imaging and resistance index measurement in the evaluation of acute renal transplant rejection.

PURPOSE: This study was designed to test the hypotheses that power Doppler imaging has a predictive value in the assessment of acute renal allograft rejection and that the information garnered from the combination of resistance index (RI) determination and power Doppler imaging has an even greater predictive value in this assessment. METHODS: Power Doppler images obtained prior to 96 sequential renal allograft biopsies in 92 patients with suspected renal transplant rejection were retrospectively graded for parenchymal vascularity on a scale of 1 to 4: 1, normal, uniform cortical flow; 2, mild peripheral cortical hypoperfusion; 3, vascular pruning in cortex and medulla; and 4, no visible parenchymal flow, with flow seen only in central vessels. Power Doppler grades and RIs for these cases were compared to graft biopsy results. RESULTS: No statistically significant association was observed between parenchymal vascularity as graded by power Doppler imaging, RI, and the presence of acute transplant rejection. CONCLUSIONS: Neither grading of vascularity on power Doppler images, RI measurement, nor the combination of these methods is an accurate means of detecting renal allograft rejection.

Acute Disease↗
PubMedDate not supplied

Idiopathic pulmonary artery aneurysm: digital subtraction pulmonary angiography grossly underestimates the size of the aneurysm.

Pulmonary artery aneurysm is a rare disease entity. The majority of cases are associated with congenital cardiovascular diseases, infection, and trauma; idiopathic pulmonary artery aneurysm is extremely rare. Although conventional and digital subtraction pulmonary angiography remains as the imaging modality of choice for the pulmonary vessels, it is invasive and sometimes may be inaccurate. With the advent of spiral computed tomographic angiography (CTA), pulmonary artery aneurysm can be diagnosed noninvasively and accurately. We report a case of a 68-year-old man with idiopathic pulmonary artery aneurysm of the descending branch of right pulmonary artery where the true caliber of the aneurysm was significantly underestimated in the digital subtraction pulmonary angiography. The literatures of this rare condition are reviewed with the emphasis on the application of CTA in this disease.

Aged↗