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Biomedical subjects

L S Fang

Publications and source records attributed to L S Fang.

At least 19 recordsLinked to original sources
PubMed2001

Estradiol and para-chlorophenylalanine downregulate the expression of brain aromatase and estrogen receptor-alpha mRNA during the critical period of feminization in tilapia (Oreochromis mossambicus).

The period of maximal feminizing action of 17beta-estradiol (E(2)) upon sex ratio is before 10 days posthatching in tilapia (Oreochromis mossambicus). The effect of E(2) at this time is mimicked by para-chlorophenylalanine (p-CPA), a serotonin (5-hydroxytryptamine; 5-HT) synthesis inhibitor. The effect of E(2) on sexual differentiation may be mediated by the 5-HT system, which is consistent with the suggestion in mammals. The masculinizing actions of 17alpha-methyltestosterone (MT) are most potent later at up to day 20 of age, and may depend on MT induction of aromatase activity. In the present study, the effects of gonadal steroids and p-CPA on brain aromatase and estrogen receptor (ER) mRNA expression during the critical period of sexual differentiation were investigated. Treatment of tilapia with E(2) resulted in a significant decrease in the expression of brain aromatase and ERalpha between days 0 and 10, but not subsequently. The effect of E(2) at this time can be mimicked by p-CPA. Treatment of tilapia with MT, by contrast, resulted in a significant increase in brain aromatase, ERalpha and ERbeta mRNA expression when given between days 10 and 20. The downregulation of brain aromatase and ERalpha mRNA expression by E(2) before 10 days of age and, in turn, the upregulation of brain aromatase and ERalpha and ERbeta mRNA expression by MT at up to day 20 of age coincide with the period in which E(2) and MT have the maximal effect on gonadal feminization and masculinization, respectively.

Actins↗
PubMed2000

Junceellolides E-G, new briarane diterpenes from the West Pacific Ocean gorgonian Junceella fragilis.

Three new diterpenes, junceellolides E-G (1-3), along with an unnamed known diterpene 4, possessing the briarane carbon skeleton, have been isolated from the gorgonian Junceella fragilis collected in Taiwanese tropical waters. The structures of the new metabolites 1-3 were elucidated by extensive spectral analyses. The six-membered rings in junceellolides E and F (1 and 2) were found to exist in boat conformations. The structure, including the relative configuration of junceellolide E (1) was further confirmed by a single-crystal X-ray analysis.

Animals↗
PubMed1998

Novel cytotoxic diterpenes, excavatolides A-E, isolated from the Formosan gorgonian Briareum excavatum.

The chemistry of Briareum excavatum, a Formosan gorgonian coral, was investigated. This study has led to the isolation of five novel marine natural products, excavatolides A-E (1-5), together with brianolide (6). The structures of the above compounds were established by spectral and chemical methods. The relative configuration of excavatolide B (2) was further confirmed by a single-crystal X-ray structure analysis. Cytotoxicity of these compounds toward various cancer cell lines also is described.

Animals↗
PubMed1997

Evaluation of renal artery stenosis with dynamic gadolinium-enhanced MR angiography.

OBJECTIVE: The purpose of this study was to compare dynamic gadolinium-enhanced three-dimensional spoiled gradient-recalled MR angiography with conventional arteriography in the evaluation of proximal renal artery stenosis (RAS). MATERIALS AND METHODS: MR angiography and conventional arteriographic examinations of 30 patients evaluated for RAS were analyzed retrospectively. Three-dimensional MR angiography was performed with an RF spoiled gradient-recalled imaging sequence acquired during the dynamic i.v. injection of gadolinium (0.2-0.3 mmol/kg), MR data and conventional arteriograms were independently evaluated for the number and location of renal arteries and the degree and location of stenoses. The patients had a mean age of 70 years old and a mean serum creatinine level of 2.9 mg/dl, reflecting a population in whom atherosclerotic RAS was the primary concern. RESULTS: Gadolinium-enhanced MR angiography revealed 100% of main renal arteries. For RAS of 50% or greater occlusion, the technique was 100% sensitive and 71% specific; the negative predictive value was 100%. The technique was 100% sensitive and 71% specific for RAS of 75% or greater occlusion. CONCLUSION: Dynamic gadolinium-enhanced three-dimensional spoiled gradient-recalled MR angiography has a high sensitivity for revealing proximal RAS and is a quick and reliable technique for obtaining helpful anatomic information.

Aged↗
PubMed1995

Atheroembolic renal failure after invasive procedures. Natural history based on 52 histologically proven cases.

Atheromatous plaque material containing cholesterol crystals may dislodge and cause distal ischemia. To characterize atheroembolic renal failure, we retrospectively evaluated all patients at the Massachusetts General Hospital from 1981 to 1990 with both renal failure and histologically proven atheroembolism after angiography or cardiovascular surgery. Over the 10-year period, 52 patients were identified. They tended to be elderly men with a history of hypertension (81%), coronary artery disease (73%), peripheral vascular disease (69%), and current smoking (50%). Within 30 days of their procedure, only 50% of patients had cutaneous signs of atheroembolism, and 14% had documented blood eosinophilia. Urinalysis was often abnormal. Hemodynamically unstable patients died shortly after their procedure, yet renal function in the remainder continued to decline over 3 to 8 weeks. Patients who received dialysis had a higher baseline serum creatinine than those who did not (168 +/- 44 mumol/L versus 133 +/- 18 mumol/L, p = 0.02), with dialysis starting a median of 29 days after the procedure. Patients with renal failure due to atheroembolism alone, as opposed to multiple renal insults, were more likely to recover renal function (24% versus 3%, p = 0.03) and had a lower risk of death during the 6 months after their procedure (log-rank p = 0.002). Renal failure due to procedure-induced AE is characterized by a decline in renal function over 3 to 8 weeks. This time course is not consistent with most other iatrogenic causes of renal failure, such as radiocontrast or nephrotoxic medications, which present earlier and often resolve within 2 to 3 weeks after appropriate intervention.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1993

Time of flight renal MR angiography: utility in patients with renal insufficiency.

We studied the renal arteries prospectively in 16 patients with renal insufficiency using a combination of two-dimensional and three-dimensional time of flight magnetic resonance angiography (MRA). Results were compared with conventional angiography. All renal arteries were identified by MRA. Accuracy for classifying renal arteries into patent, moderately (30-70%) stenotic, severely (> 70%) stenotic, or occluded was 91%. With regard to the presence or absence of severe occlusive disease (> 70% stenosis or occlusion) the sensitivity was 100%, with a specificity of 93%.

Aged↗
PubMed1993

Renal function in patients at risk of contrast material-induced acute renal failure: noninvasive, real-time monitoring.

Real-time changes in renal function were studied in a group of 20 patients at risk of contrast-material-induced acute renal failure during different angiographic procedures. Renal function was evaluated with an ambulatory renal monitor (ARM) after a single injection of the glomerular filtration agent technetium-99m diethylenetriaminepentaacetic acid (DTPA). The ARM was used to continuously monitor the clearance of Tc-99m DTPA activity from the extracellular space in the arm of the patient during angiography. A one-compartment model was used to calculate on-line the rate constant for clearance of Tc-99m DTPA from the extracellular space. Changes in the rate constant were compared with changes in plasma creatinine level measured 1-4 days after angiography. The results showed that the ARM measured rapid changes in renal function during angiography with a resolution time of 5-10 minutes in patients with normal to moderately decreased renal function and 15-20 minutes in patients with severe renal dysfunction. The sensitivity of this technique was superior to that of plasma creatinine level analysis.

Acute Kidney Injury↗
PubMed1990

Purification and characterization of bilirubin UDP-glucuronyltransferase from the liver of eel, Anguilla japonica.

1. The enzyme bilirubin uridine diphosphate glucuronyltransferase (UDPGT) was purified and characterized from the liver of eel, Anguilla japonica. 2. The molecular weight of the enzyme was 88,000. 3. The optimal working pH of the enzyme was 7.5-8.0. The optimal working temperature of the enzyme was around 46 degrees C. 4. The Km of bilirubin and uridine diphosphate glucuronic acid for this enzyme was 1.6 mM and 1.8 mM respectively. 5. The concentration of bilirubin did not show any significant effect of inhibition on this enzyme up to 3.3 mM. 6. Since this is the first time UDPGT has been purified and characterized from poikilothermic aquatic animals, it provided interesting information on evolution and adaptation of this enzyme when compared to that of mammals.

Anguilla↗
PubMed1990

The blue-green blood plasma of marine fish.

1. The blue-green coloration of the blood plasma in some marine fishes, which is attributed to a protein bound tetrapyrrol (biliverdin), is an anomaly in vertebrates. 2. Recent studies have shown that biliverdin not only occurs in many fish, but is also present in the blood of tobacco hornworm, the wings of moth and butterfly, the shell of bird eggs, the serum and egg of frog, the placenta of dog and in the blood of humans suffering from hepatic diseases. 3. In this review, we begin with a historical account of the description of the presence of blue-green blood plasma in fish, and then consider the biochemistry, metabolism, physiology, and the ecological implications of biliverdin in fish. 4. A comparative description of the occurrence of biliverdin in fish and other animals is presented. 5. The mechanism of accumulation of biliverdin in fish blood and its evolutionary significance are also considered. It is suggested that this process may serve as a useful model for further research on bile pigment metabolism in other animals.

Animals↗
PubMed1988

Urinalysis in the diagnosis of urinary tract infections.

Urinary tract infection is the commonest human bacterial infection. Bacteriuria alone does not appear to produce progressive renal damage or hypertension. However, it can produce considerable morbidity. Urinalysis is a simple, relatively sensitive, and reliable way of diagnosing urinary tract infection. It is not clear that routine screening should be performed in all patients, but pregnant females, patients with known anatomic abnormalities, and patients with recent genitourinary instrumentation should be screened. The major determinant of therapeutic success in patients with urinary tract infections is the anatomic site of infection. Superficial mucosal infection of the bladder is well treated with a single dose of an appropriate antibiotic, whereas deep tissue infection of the kidney or prostate should be treated with a prolonged and intensive course of therapy. Urinalysis is an insensitive tool in the localization of infection. However, the presence of white cell casts on the examination of the urinary sediment is pathognomonic of upper tract infection and would lead one to pursue an aggressive course of therapy. Examination of the concentrating ability is of limited help in this regard because of the wide range of overlap of concentrating ability in patients with upper and lower tract infections. In selected instances, urinalysis is of help in guiding therapy of urinary tract infections. This is particularly true of the patients with acute urethral syndrome where therapy is guided by the presence or absence of pyuria. Urinalysis, a simple front-line test, is of paramount importance in the evaluation and management of the patient with urinary tract infection.

Antibody-Coated Bacteria Test, Urinary↗
PubMed1987

Prediction of outcome in acute renal failure.

In an attempt to predict outcome in acute renal failure (ARF) we have utilized multiple logistic regression to analyze clinical data from 151 patients with ARF seen over a 15-month period. Recovery of renal function occurred in 60% of patients with a 58% survival. Our analysis demonstrated sepsis, respiratory failure, and oliguria to be the major predictors of nonrecovery of renal function. A logistic equation was generated for prediction of outcome and was validated in a second independent group of patients with ARF. Prediction of outcome could be achieved with a sensitivity of 75% and a specificity of 80%. Maximum sensitivity (100%) was associated with a 17% specificity, while maximum specificity (98%) yielded a sensitivity of 20%.

Acute Kidney Injury↗
PubMed1986

A comparative study on the binding characteristics of the tight serum biliverdin-protein complexes in two fishes: Anguilla japonica and Clinocottus analis.

The binding characteristics of biliverdin to its carrier protein in the blue-green blood of Clinocottus analis (woolly sculpin) and Anguilla japonica (freshwater eel) were operationally defined by various chemical probing methods and spectra analysis. The biliverdin in C. analis is a rotatable coiled molecule enveloped in a hydrophobic pocket of its carrier protein. The biliverdin in A. japonica is an open form molecule with external hydrogen bond or weak ester bond interacting with the carrier protein. This, for the first time, shows that the novel firm binding biliprotein complexes in the blood of different species are biochemically different. Their comparative and evolutionary significance is discussed.

Anguilla↗
PubMed1985

Pharmacokinetics of intravenous amdinocillin in healthy subjects and patients with renal insufficiency.

Five healthy volunteers and 31 patients with various degrees of renal impairment received a 10-mg/kg intravenous dose of amdinocillin by infusion over 15 min to establish the disposition profile of the drug in plasma and urine. Both clearance from plasma and elimination rate constant showed a linear relationship with creatinine clearance. It was noted that in subjects with creatinine clearances of greater than 50 ml/min, the elimination half-life remained relatively constant; however, as the creatinine clearance decreased from 50 to 5 ml/min, there was a progressive rise in the elimination half-life. Despite the removal of the drug by hemodialysis (32 to 72% of the dose), concentrations of amdinocillin in plasma remained in the therapeutic range. In patients undergoing peritoneal dialysis, less than 4.0% of the infused dose was removed by dialysis during the hourly exchanges over a 14- to 18-h period. Although the clearance from plasma and the half-life of amdinocillin were altered up to fourfold in patients with creatinine clearances of less than 15 ml/min, the amdinocillin dosage per se may not need to be reduced for these patients if the frequency of dosing is reduced from six to three or four times daily. This is based on drug accumulation estimates of 56% from a regimen of 10 mg/kg every 8 h in these patients as compared with less than 10% from a regimen of 10 mg/kg every 4 h in subjects with normal renal function. In addition, supplemental doses may not be necessary during or at the end of hemodialysis for patients undergoing hemodialysis.

Adult↗