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Biomedical subjects

T L Lee

Publications and source records attributed to T L Lee.

At least 91 records · Page 5Linked to original sources
PubMed1990

Mycobacterium chelonei keratopathy with visual rehabilitation by a triple procedure.

We report a chronic keratouveitis following an eye injury, the etiology of which remained obscure despite repeated corneal scrapings and cultures. Eventually, the diagnosis was established by culturing Mycobacterium chelonei from a corneal biopsy specimen. Topical amikacin resolved active inflammation, but dense corneal scarring and a cataract remained. Visual rehabilitation was achieved through a combined penetrating keratoplasty, extracapsular cataract extraction, and intraocular lens implantation. This case illustrates that there should be a high index of suspicion of atypical mycobacteria when faced with any unusual keratitis, particularly following penetrating injuries and corneal grafts.

Cataract Extraction↗
PubMed1990

Malignant hyperthermia.

Two cases of malignant hyperthermia (MH) are presented. The first patient presented initially with tachyarrhythmia intraoperatively and rapid onset of MH crisis. Nasopharyngeal temperature of 43 degrees C was attained after 15-20 minutes of anaesthesia. The patient eventually died of myocardial failure despite external cardiac massage, inotropic support and ventricular pacing. The second patient presented with increasing endogenous hypercarbia following the administration of suxamethonium and isoflurane. The use of the end tidal carbon dioxide monitor led to an early diagnosis of MH. The early use of dantrolene may have contributed to the favourable outcome.

Adult↗
PubMed1988

Interaction of B16 malignant melanoma tumor cells with the murine mesentery in vitro.

We have used organs cultures of murine mesentery as a model system to investigate the mechanisms by which B16-F10 melanoma cells invade normal tissues. The mesentery has the advantage of being a real tissue, consisting of a loose connective tissue, containing a normal complement of stromal cells and extracellular matrix, covered by a continuous epithelium of squamous mesothelial cells which are separated from the connective tissue by a laminin-containing basement membrane. B16-F10 cells seeded onto the mesentery in vitro cause a local retraction of the mesothelial cells exposing the underlying basement membrane onto which the tumor cells spread. Direct contact between the tumor cells and the margins of the mesothelial cells is required to induce retraction. Most of the B16 cells remain on the surface of the mesentery where they spread on the basement membrane without disrupting it. A few B16 cells penetrate the basement membrane and invade the connective tissue interior of the mesentery where they flatten out and assume a fibroblastic morphology. Tumor cells within the connective tissue may continue to translocate and they adhere to and move along the fibers of the connective tissue extracellular matrix without appearing to destroy or disrupt them.

Animals↗
PubMed1986

Determination of piquindone in canine plasma and urine by high-performance liquid chromatography.

This report describes a rapid, sensitive and selective method for the determination of piquindone in canine plasma and piquindone and the N-demethyl metabolite of piquindone in canine urine, utilizing normal-phase high-performance liquid chromatography (HPLC) with isocratic elution at ambient temperature and monitoring the ultraviolet absorbance of the eluent at 254 nm. The trimethyl analogue of piquindone is used as the internal standard in the HPLC assay of plasma. The assay was applied to the measurement of concentrations of piquindone in the plasma and urine of a dog following single intravenous and oral administration of 5 mg/kg doses of piquindone hydrochloride dihydrate.

Administration, Oral↗
PubMed1985

Determination of 4-amino-5-ethyl-3-thiophenecarboxylic acid methyl ester and its acid metabolite in plasma and urine by high-performance liquid chromatography.

Two separate, rapid, sensitive and selective high-performance liquid chromatographic (HPLC) assays were developed for the determination of 4-amino-5-ethyl-3-thiophene-carboxylic acid methyl ester (I) and its acid metabolite, 4-amino-5-ethyl-3-thiophene-carboxylic acid (II), in plasma and urine. The analysis of I is performed directly on a hexane extract of plasma or urine (buffered to pH 11) by normal-phase HPLC analysis using a 10-micron silica gel column with an eluting solvent of hexane-ethanol (95:5) and UV detection of the effluent at 254 nm. A methyl analogue, 4-amino-5-methyl-3-thiophenecarboxylic acid methyl ester, was used as the internal standard. The analysis of II is performed on the residue of either a diethyl-ether-washed protein-free filtrate of plasma or a methylene chloride-isopropanol (95:5) extract of urine (buffered to pH 5.3) using a 10-micron alkyl phenyl (reversed-phase) column with an eluting solvent of water-methanol-1 M phosphoric acid, pH 2.5 (70:30:0.05) with UV detection of the effluent at 254 nm. An isopropyl analogue, 4-amino-5-isopropylthiophene-3-carboxylic acid (IV), was used as the internal standard. The assay of compounds I and II were applied to the determination of plasma and urine concentrations of I and II in the dog and in man following oral administration of I X HCl. The data obtained demonstrated the extremely rapid and virtually complete deesterification of I (ester) to II (acid) in both species.

Animals↗
PubMed1985

Review of problems of massive blood transfusion in a surgical intensive care unit.

A retrospective review of 29 surgical patients who were massively transfused perioperatively according to a standard transfusion protocol was carried out. Volume of blood transfused was 2,300 mls to 12,440 mls, with a mean of 5,168 mls. Results of this study showed: administration of bicarbonate should be individualised and based on blood gas analysis. deficiency in factor V and factor VIII in CPD adenine blood did not cause disturbance in haemostasis. Postoperative thrombocytopenia was significant, 89.28% had platelet count less than 150 X 10(9)/L. Further drop in platelet count was observed 24 hours postoperatively. Hyperkalaemia was not observed, hypokalaemia following surgery with massive blood transfusion was observed in 53.6% of our patients.

Acid-Base Imbalance↗
PubMed1983

Determination of cibenzoline in plasma and urine by high-performance liquid chromatography.

A rapid, sensitive and selective high-performance liquid chromatographic (HPLC) assay was developed for the determination of cibenzoline (CipralanTM) in human plasma and urine. The assay involves the extraction of the compound into benzene from plasma or urine buffered to pH 11 and HPLC analysis of the residue dissolved in acetonitrile-phosphate buffer (0.015 mol/l, pH 6.0) (80:20). A 10-microns ion-exchange (sulfonate) column was used with acetonitrile-phosphate buffer (0.015 mol/l, pH 6.0) (80:20) as the mobile phase. UV detection at 214 nm was used for quantitation with the di-p-methyl analogue of cibenzoline as the internal standard. The recovery of cibenzoline in the assay ranged from 60 to 70% and was validated in human plasma and urine in the concentration range of 10-1000 ng/ml and 50-5000 ng/ml, respectively. A normal-phase HPLC assay was developed for the determination of the imidazole metabolite of cibenzoline. The assays were applied to the determination of plasma and urine concentrations of cibenzoline and trace amounts of its imidazole metabolite following oral administration of cibenzoline succinate to two human subjects.

Chromatography, High Pressure Liquid↗
PubMed1982

Determination of amdinocillin in plasma and urine by high-performance liquid chromatography.

A rapid, sensitive and specific high-performance liquid chromatographic (HPLC) assay was developed for the determination of amdinocillin (formerly mecillinam) in human plasma and urine. The assay is performed by direct injection of a plasma protein-free supernatant or a dilution of urine. A 10 micrometer muBondapak phenyl column with an eluting solvent of water--methanol--1 M phosphate buffer, pH 7 (70:30:0.5) was used, with UV detection of the effluent at 220 nm. Azidocillin potassium salt [potassium-6-(D-(-)-alpha-azidophenyacetamido)-penicillanate] was used as the internal standard and quantitation was based on peak height ratio of amdinocillin to that of the internal standard. The assay has a recovery of 74.4 +/- 6.3% (S.D.) in the concentration ranges of 0.1-20 microgram per 0.2 ml of plasma with a limit of detection equivalent to 0.5 microgram/ml plasma. The urine assay was validated over a concentration range of 0.025-5 mg/ml of urine, and has a limit of detection of 0.025 mg/ml (25 microgram/ml) using a 0.1-ml urine specimen per assay. The assay was applied to the determination of plasma and urine concentrations of amdinocillin following intravenous administration of a 10 mg/kg dose of amdinocillin to two human subjects. The HPLC and microbiological assays were shown to correlate well for these samples.

Amdinocillin↗
PubMed1979

High-pressure liquid chromatographic determination of amoxicillin in urine.

A rapid and specific high-pressure liquid chromatographic (HPLC) assay was developed for the simultaneous determination of amoxicillin and its pencilloic acid metabolite in urine. The two compounds, assayed directly in urine or after dilution with water-methanol (85:15), are separated by reversed-phase chromatography and quantitated spectrofluorometrically following postcolumn derivatization with fluorescamine. Linear calibration curves were measured in the ranges of 25-250 and 50-400 ng injected for amoxicillin and the penicilloic acid metabolite, respectively. The sensitivity limit of the assay is 2.5-5.0 microgram/ml of urine for amoxicillin and the penicilloic acid metabolite. Urine samples (0-8 hr) taken from six subjects following single 250-mg po doses and assayed by HPLC showed ranges of cumulative percent of the dose excreted as amoxicillin and the penicilloic acid metabolite (reported as amoxicillin equivalents) of 50.2-68.0, and 21.6-30.0%, respectively. An excellent correlation (r = 0.985) was demonstrated for the measurement of amoxicillin concentrations by the HPLC and microbiological assays.

Amoxicillin↗
PubMed1979

Simultaneous automated determination of free and total sulfisoxazole and sulfamethoxazole in plasma and urine.

A fully automated method for the determination of sulfisoxazole, N4-acetylsulfisoxazole, sulfamethoxazole, and N4-acetylsulfamethoxazole in human plasma and urine was developed. Untreated plasma is analyzed by automation of dialysis, hydrolysis, color development, and quantitation. The method has a sensitivyt limit of 2 microgram/ml of plasma and has been used successfully to determine sulfonamide levels following administration of sulfoxazole and a combination drug product containing sulfamethoxazole and trimethoprim in humans. Samples are processed at the rate of 40 per hour, with a minimum of sample handling, data reduction, and materials.

Autoanalysis↗
PubMed1978

Chemotaxis of Salmonella typhimurium to amino acids and some sugars.

Patterns of chemotaxis by Salmonella typhimurium strain LT-2 to l-amino acids and to several sugars were quantitated by the Adler capillary procedure. Competition experiments indicated that LT-2 possesses three predominant receptors, or interacting sets of receptors, for amino acids. These were termed the aspartate, serine, and alanine classes, respectively. Studies with strains carrying point and deletion mutations affecting components of the phosphoenolpyruvate: glycose phosphotransferase system (PTS) made unlikely a role in primary reception of d-glucose by the three soluble PTS components, namely HPr, enzyme I, and factor III. A ptsG mutant defective in membrane-bound enzyme IIB' of the high-affinity glucose transport system was shown to exhibit normal chemotaxis providing pleiotropic effects of the mutation were eliminated by its genotypic combination with other pts mutations or, phenotypically, by addition of cyclic AMP and substrate. A correlation was demonstrated between chemotaxis to glucose and activity of the low-affinity glucose transport complex, membrane-bound enzymes IIB:IIA, and an enzyme IIB:IIA mutant was shown to have a preponderant defect in chemotaxis to glucose and mannose. Of four systems capable of galactose transport, only the beta-methylgalactoside transport system was implicated in chemotaxis to galactose. Some properties of a mutant possibly defective in processing of signals for chemotaxis to sugars is described.

Amino Acids↗