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Biomedical subjects

L J Lee

Publications and source records attributed to L J Lee.

12 recordsLinked to original sources
PubMed1997

Medical necessity for right heart catheterization.

Because there are no definitive guidelines for performing right heart catheterizations or controlled clinical trials demonstrating medical benefit, the value and necessity of performing routine right heart catheterizations for coronary artery disease have been questioned. This Texas Medical Foundation Health Care Quality Improvement Program project was designed to ensure medical necessity and proper documentation of right heart catheterization when performed as part of a bilateral procedure. Medicare claims data were used to identify Texas facilities where rates of bilateral catheterizations suggested that right heart catheterizations were being performed routinely. Five facilities were found to have rates of bilateral procedures exceeding 70%. Suggested guidelines for performing right heart catheterizations were prepared by the Texas Medical Association Committee on Cardiovascular Diseases. These guidelines, together with the facility's data on its rate of right heart catheterizations, were presented by the Texas Medical Foundation to the staff of each facility. They were asked to examine their individual facility's procedures for ensuring medical necessity and to develop and implement process improvement plans. Medicare claims data were analyzed to determine the rates of bilateral catheterizations before and after the plans were instituted. The statewide rate of bilateral procedures decreased from 27.2% to 21.3% (p < 0.005). Rate reductions for 4 facilities implementing improvement plans were statistically significant (p < 0.001): at the 1st facility, the rate decreased from 74.3% to 25.0%; at the 2nd, from 85.0% to 21.0%; at the 3rd, from 76.7% to 17.7%; and at the 4th facility, from 85.4% to 42.9%. The rate for the facility not implementing an improvement plan increased from 86.4% to 89.1%. Reductions in rates of bilateral procedures at the 4 facilities suggest that many procedures previously performed were routine and not medically indicated. Presentation of data and practice guidelines to facilities may have contributed to their ability to improve processes.

Cardiac Catheterization↗
PubMed1996

A protective anti-peptide antibody against the immunodominant site of the A24 Cruzeiro strain of foot-and-mouth disease virus and its reactivity with other subtype viruses containing the same minimum binding sequence.

A synthetic peptide vaccine of the general sequence Cys-Cys-(200-213)-Pro-Pro-Ser-(l41-158)-Pro-Cys-Gly(peptide A40), where the numbered residues refer to the VP1 sequence of foot-and-mouth disease virus (FMDV) strain A24 Cruzeiro, has previously been shown to elicit neutralizing and protective antibodies in guinea-pigs and cattle. To examine this immunogenic tract in more detail monoclonal antibodies (MAbs) were raised to this peptide. One such MAb C1.1, which recognized the homologous peptide, bound to native virus, neutralized infectivity in vitro and passively protected mice from challenge. Using overlapping dodecameric peptides the minimum binding 'footprint' of this MAb incorporated residues 149-154 which were respectively Gly-Ser-Leu-Ala-Ala-Arg. Since this 'footprint' occurs in several other A subtype strains of FMDV, the extent to which MAb C1.1 could cross-react was also examined. Using a liquid-phase competition ELISA, only viruses with a sequence that encompassed the same minimum binding 'footprint', namely A27 Cundinamarca Colombia/76, A Argentina/79, and A Venceslau Brazil/76 reacted with similar affinity against MAb C1.1. However, further serological examination of C1.1 with these viruses by indirect ELISA, in vitro neutralization and passive protection showed clear functional disparity. In contrast to the liquid-phase ELISA, the ability of C1.1 to react with electrostatically bound virus varied significantly depending on the subtype examined. Moreover, the capacity of this MAb to neutralize these subtypes showed wide divergence which was mirrored by the protection data.

Amino Acid Sequence↗
PubMed1995

The effects of recombinant human insulin-like growth factor (rhIGF)-1 and rhIGF-1/IGF binding protein-3 administration on rat osteopenia induced by ovariectomy with concomitant bilateral sciatic neurectomy.

We compared the effect of administration of recombinant human insulin-like growth factor-1 (rhIGF-1) alone or the rhIGF-1/IGF binding protein-3 (IGFBP-3) complex on osteopenia in rats. Female Sprague-Dawley rats (8 months old) underwent combined ovariectomy and bilateral sciatic neurectomy (OVX-NX) or sham operation only. After 2 months, the OVX-NX animals were injected subcutaneously with rhIGF-1 alone or with rhIGF-1A IGFBP-3 equimolar complex for 4 weeks. The IGF-1 contents and dose were 0.3 mg/kg of body weight (BW) three times/week, 3 mg/kg of BW once/week, or 3 mg/kg of BW three times /week. At the end of the experiment, the 4th and 5th lumbar vertebrae (L4, L5) and the proximal tibiae were removed after tetracycline labeling, and histomorphometrical analyses were performed on undecalcified sections using Villanueva's staining. The cancellous bone volume at L5 significantly increased by thickening of the trabecular width in rats treated with the complex. However, the increase in the values at the proximal tibia was not significant. The bone formation rates (BFR/BS) in the lumbar vertebrae of rats treated with the complex three times a week at doses of 0.3 mg/kg of BW and 3 mg/kg of BW were both significantly increased but the parameter increase was less marked with the dose of 3 mg/kg of BW once/week. The BFR/BS did not increase significantly in animals treated with IGF-1 alone. These findings clearly demonstrated that the effect of systemically administered rhIGF-1 on bone formation was markedly potentiated when combined with IGFBP-3 in estrogen deficiency combined with reduced activity. The action of IGF-1 was less potent on the bone in paralyzed limbs. The action of rhIGF-1/IGFBP-3 on trabecular bone appeared to depend not only on the dose but also on the frequency of administration and the parts of the skeleton in rats.

Analysis of Variance↗
PubMed1994

Purification of dopamine neurons by flow cytometry.

The heterogeneity and preponderence of other cell types present in cultures has greatly impeded our ability to study dopamine neurons. In this report, we describe methods for isolating nearly pure dopamine neurons for study in culture. To do so, the lipid-soluble dye, 1,1'-dioctadecyl-3,3,3'3'-tetramethylindocarbocyanine perchlorate (diI) was injected into the embryonic rat striata where it was taken up by nerve terminals and transported overnight back to the innervating perikarya in the ventral midbrain. Midbrain cells were then dissected, dissociated and separated on the basis of their (rhodamine) fluorescence by flow cytometry. Nearly all cells recovered as fluorescent positive (> 98%) were also immunoreactive for the dopamine specific enzyme tyrosine hydroxylase (80%-96%). Little contamination by other cells types was observed after labeling for specific neuronal and glial markers. Purified dopamine neurons continued to thrive and elaborate neuronal processes for at least 3 days in culture. Using this new model, it may now be possible to directly study the cellular and molecular processes regulating the survival and functioning of developing, injured and transplanted dopamine neurons.

Animals↗
PubMed1988

Renal transport kinetics of chlorothiazide in the isolated perfused rat kidney.

The effect of protein binding on the renal excretion of chlorothiazide was examined in the isolated perfused rat kidney. Drug studies were performed in three rats at 6.00% bovine serum albumin + 0% dextran and in three rats at 0.25% bovine serum albumin + 3.83% dextran. Chlorothiazide was introduced into the recirculating perfusate at an initial concentration of 100 micrograms/ml, and was assayed using high-performance liquid chromatography. Functional viability of the kidney was assessed by measuring the fractional excretion of sodium and glucose, and the glomerular filtration rate. The protein binding of drug in perfusate was determined by equilibrium dialysis. These experimental conditions resulted in an approximate 14-fold increase of percent free (from 5.3-72.0%), and a 3-fold increase of renal (from 1.03-3.30 ml/min) and secretion (from 1.01-2.83 ml/min) clearances. The data were best fitted by a model in which one Michaelis-Menten term was used to describe active transport, and secretion was dependent upon free concentrations of chlorothiazide in the perfusate. The maximum velocity of secretion (Vm = 85.6 micrograms/min) and Michaelis constant (Km = 2.1 micrograms/ml) of chlorothiazide was estimated using a nonlinear least-squares regression program. These results suggest that for compounds of low renal extraction, free drug concentrations are the driving force for carrier-mediated tubular secretion.

Animals↗
PubMed1986

Renal transport kinetics of furosemide in the isolated perfused rat kidney.

Direct quantitative data and corresponding theory are provided for the effect of protein binding on the renal transport of furosemide. Drug studies were performed with various combinations of bovine serum albumin and dextran. This resulted in a percent unbound (fu) of furosemide ranging from 0.785 to 85.8%. The corrected renal (CLr/GFR) and secretion (CLs/GFR) clearances of furosemide were observed to increase with percent free, but in a nonproportional manner. Plots of CLr/GFR or CLs/GFR vs. fu appeared to have a prominent y intercept as well as a convex ascending curve. In addition, the excretion ratio [ER = CLr/(fu . GFR)] was reduced from 60.8 to 8.72 as fu increased. Overall, the data were best fitted to a model in which two Michaelis-Menten terms were used to describe renal tubular transport, and secretion was dependent upon free drug concentrations in the perfusate. The results demonstrate that the renal mechanisms of furosemide excretion are more complex than previously reported and that active secretion may involve two different transport systems over the concentration range studied.

Animals↗
PubMed1984

Grief work with substance abusers.

This article focuses on the implementation and outcome of a grief group study conducted with substance abusers. Group participants were chosen through a stratified random sampling from a residential drug and alcohol treatment facility. Control and experimental groups were used to test the efficacy of grief group therapy. Study results indicated that treatment group participants were significantly less depressed and better able to resolve painful feelings about their losses. The grief group approach is generic and can be modified to meet the needs of varied target groups. The distinctive approach and the empirical results both were completed by a clinician without disrupting the facility, patients or clinician's daily practices.

Adaptation, Psychological↗
PubMed1982

Cloning and expression of the beta-D-phosphogalactoside galactohydrolase gene of Lactobacillus casei in Escherichia coli K-12.

Lactose metabolism in Lactobacillus casei 64H is associated with the presence of plasmid pLZ64. This plasmid determines both phosphoenolpyruvate-dependent phosphotransferase uptake of lactose and beta-D-phosphogalactoside galactohydrolase. A shotgun clone bank of chimeric plasmids containing restriction enzyme digest fragments of pLZ64 DNA was constructed in Escherichia coli K-12. One clone contained the gene coding for beta-D-phosphogalactoside galactohydrolase on a 7.9-kilobase PstI fragment cloned into the vector pBR322 in E. coli strain chi 1849. The beta-D-phosphogalactoside galactohydrolase enzyme isolated from E. coli showed no difference from that isolated from L. casei, and specific activity of beta-D-phosphogalactoside galactohydrolase was stimulated 1.8-fold in E. coli by growth in media containing beta-galactosides. A restriction map of the recombinant plasmid was compiled, and with that information, a series of subclones was constructed. From an analysis of the proteins produced by minicells prepared from transformant E. coli cells containing each of the recombinant subclone plasmids, it was found that the gene for the 56-kilodalton beta-D-phosphogalactoside galactohydrolase was transcribed from an L. casei-derived promoter. The gene for a second protein product (43 kilodaltons) was transcribed in the opposite direction, presumably under the control of a promoter in pBR322. The relationship of this second product to the lactose metabolism genes of L. casei is at present unknown.

Cloning, Molecular↗
PubMed1978

Presence of a single enzyme catalyzing the pyrophosphorolysis of UDP-glucose and UDP-galactose in Bifidobacterium bifidum.

The enzyme preparation catalyzing the pyrophosphorolyses of UDP-glucose and UDPgalactose almost at the same rate was purified about 900-fold from Bifidobacterium bifidum grown on glucose medium. The two activities were always associated with each other, and their activity ratio was always constant throughout the purification steps. The final preparations was revealed homogeneous by polyacrylamide gel electrophoresis in the presence and absence of sodium dodecyl sulfate. There was no significant difference in thermal stabilities of the two activities. From these results it was concluded that the UDPglucose and UDPgalactose pyrophosphorylase activities in B. bifidum are catalyzed by a single enzyme protein.

Actinomycetaceae↗
PubMedDate not supplied

Effect of organ perfusion on renal drug transport. Application to furosemide in the isolated perfused rat kidney.

Angiotensin II was used as a probe to study the effect of changes in perfusate flow rate on the renal clearance parameters of furosemide in the isolated perfused rat kidney. Drug studies were performed in three rats with no angiotensin II present in the perfusate (treatment I) and in three rats with a 2.7 ng/min infusion of angiotensin II into the perfusate (treatment II). Furosemide was introduced into the recirculating perfusate at an initial concentration of 3.5 micrograms/ml and was assayed using HPLC. The protein binding of furosemide in perfusate was determined by equilibrium dialysis. Angiotensin II was found to have a dramatic effect on the renal hemodynamics, resulting in a 42% decrease in perfusate flow, a 27% decrease in GFR, and a 25% increase in filtration fraction. Values for the fractional excretion of glucose were very low and consistent, with or without angiotensin II (3.0-3.5%). Although the fraction unbound of furosemide was unchanged between treatments (0.770 for treatment I vs. 0.695% for treatment II), the renal and secretion clearances of furosemide were reduced by about 30% in the presence of angiotensin II. However, if the renal clearance (CLr) was corrected for free fraction (fu) and glomerular filtration rate (GFR) [ER = CLr/(fu.GFR)], there was no difference between the excretion ratio (ER) values of furosemide after the two treatments (29.0 for treatment I vs. 29.6 for treatment II). These results imply that the altered clearance parameters of furosemide are more likely the consequence of a reduction in functional nephron mass rather than a change in intrinsic secretory transport per unit mass of nephron.

Angiotensin II↗