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Biomedical subjects

J Lever

Publications and source records attributed to J Lever.

At least 19 recordsLinked to original sources
PubMed1997

Pregnancy after liver transplantation under tacrolimus.

BACKGROUND: The maternal and fetal risk of pregnancy after organ transplantation under tacrolimus has not been reported. This was prospectively studied in 27 pregnancies by 21 female liver recipients who were treated with tacrolimus before and throughout gestation. METHOD: Twenty-seven babies were born between October 1990 and April 1996. In 15 cases, samples were obtained at or after delivery and stored (-40 degrees C) for comparison of tacrolimus concentration in the maternal blood with different combinations of cord and infant venous blood, breast milk, or a section of the placenta. RESULTS: The 21 mothers had surprisingly few serious complications of pregnancy and no mortality. Two infants with 23 and 24 weeks gestation died shortly after birth. The mean birth weight of the other 25 was 2638+/-781 g after a gestational period of 36.6+/-3.3 weeks. Mean birth weight percentile for gestational age was 50.2+/-26.2 (median 40). On the day of delivery, the mean tacrolimus concentrations (ng/ml) were 4.3 in placenta versus 1.5, 0.7, and 0.5 in maternal, cord, and child plasma, and 0.6 in the first breast milk specimens. The infants had a 36% incidence of transient perinatal hyperkalemia (K+>7.0 meq/L) and a mild reversible renal impairment, which were thought to reflect in part maternal homeostasis. One newborn had unilateral polycystic renal disease (the only anomaly). All 25 babies have had satisfactory postnatal growth and development with a current mean weight percentile of 62+/-37 (median 80). CONCLUSIONS: Pregnancy by postliver transplant mothers under tacrolimus was possible with a surprisingly low incidence of the hypertension, preeclampsia, and other maternal complications historically associated with such gestations. As in previous experience with other immunosuppressive regimens, preterm deliveries were common. However, prenatal growth for gestational age and postnatal infant growth for postpartum age were normal.

Adult↗
PubMed1996

Functional outcome of thoracolumbar burst fractures without neurological deficit.

Thoracolumbar burst fractures are a major cause of disability; however, there are few studies on the functional outcome of patients with this injury. The purpose of this study is to evaluate the functional outcome of patients with thoracolumbar burst fractures using a generic and a condition-specific health status survey. The SF-36 survey (generic) and the Roland scale (condition-specific) were administered to 24 patients who had a minimum of 2 years follow-up after a thoracolumbar burst fracture without neurologic deficit. The average SF-36 score was 65% (compared to 45% for dialysis and 66% for diabetes) and the Roland score was 65% (compared to 58% for low back pain). Of the patients, 33% were able to return to their previous employment, but only 8% were able to return to their pre-injury level of sports. There was a strong correlation (r = 0.71) between the Roland scale and the SF-36 pain scale. There were poor correlations between the Roland scale and residual kyphosis (r = 0.003), and between the SF-36 pain scale and residual kyphosis (r = 0.10). There was no significant difference in the functional outcome of those patients treated operatively versus nonoperatively.

Adult↗
PubMed1995

Capillary blood versus arterial or venous blood for tacrolimus monitoring in liver transplantation.

Tacrolimus has been found to be useful in clinical solid organ transplantation. A very careful monitoring of the tacrolimus levels and dose adjustments are essential, at least in the immediate post-liver transplantation, situation. However, quite often after liver transplantation, patients have limited venous access for daily monitoring of tacrolimus levels. When the blood is sampled from a multilumen central venous catheter, used also for intravenous administration of tacrolimus, falsely elevated concentrations of tacrolimus have been observed. The present study examines the concentration of tacrolimus in capillary blood samples obtained from finger stick and compares its concentrations in simultaneously drawn samples from arterial line, peripheral venous puncture, and multilumen centrally placed venous catheter from the port used for tacrolimus infusion and the port not used for tacrolimus infusion. Ten adult post-liver transplantation recipients were studied. Whole blood concentration of tacrolimus in capillary blood was comparable to that of arterial blood, as well as to that of peripheral venous blood samples (r2 = 0.99; P = 0.72). Concentrations of tacrolimus in venous blood drawn from the port of the multilumen catheter used for intravenous tacrolimus infusion were 3-23 times higher (P = 0.0015), while the concentrations of venous blood drawn from the port not used for tacrolimus infusion were 1.7-4.5 times higher (P = 0.016), as compared with arterial, capillary, or peripheral venous whole blood concentrations.

Adult↗
PubMed1995

Tacrolimus analysis: a comparison of different methods and matrices.

We determined the through blood and plasma concentrations of tacrolimus from the day of transplantation through 30 days posttransplantation in four liver and four kidney transplant patients by three different methods. The first method involved a solid phase extraction of the blood or plasma using Sep-Pak columns (SPs) followed by quantitation of tacrolimus using an enzyme-linked immunosorbent assay (ELISA); the second method involved a liquid-liquid extraction using methylene chloride (MC) followed by quantitation of tacrolimus using the ELISA, and the third method involved a high-performance liquid chromatography (HPLC) fractionation of the extract obtained from the solid-phase extraction and quantitation of tacrolimus in the fractions by ELISA. The trough plasma tacrolimus concentrations ranged from 0.1 to 5.2 ng/ml. While the trough plasma concentrations of tacrolimus were similar and independent of the method of analysis in kidney transplant patients and in liver transplant patients with normal biochemical profile, in patients with liver dysfunction, tacrolimus plasma concentrations were higher when measured by SP-ELISA and MC-ELISA methods as compared to the HPLC-ELISA method. In plasma samples obtained from liver transplant patients with liver dysfunction, the presence of some metabolites that cross-reacted with the antibody used in the ELISA could be documented in the HPLC fraction corresponding to the metabolites. This indicates that while tacrolimus metabolites that cross-react significantly with the antibody used in the ELISA do not accumulate in kidney transplant patients, they can appear in the plasma of patients, they can appear in the plasma of patients with liver dysfunction. The trough blood tacrolimus concentrations in patients were significantly higher than the corresponding plasma concentrations and ranged from 1.4 to 107 ng/ml.(ABSTRACT TRUNCATED AT 250 WORDS)

Chromatography, High Pressure Liquid↗
PubMed1995

Clinical pharmacokinetics of tacrolimus.

Tacrolimus, a novel macrocyclic lactone with potent immunosuppressive properties, is currently available as an intravenous formulation and as a capsule for oral use, although other formulations are under investigation. Tacrolimus concentrations in biological fluids have been measured using a number of methods, which are reviewed and compared in the present article. The development of a simple, specific and sensitive assay method for measuring concentrations of tacrolimus is limited by the low absorptivity of the drug, low plasma and blood concentrations, and the presence of metabolites and other drugs which may interfere with the determination of tacrolimus concentrations. Currently, most of the pharmacokinetic data available for tacrolimus are based on an enzyme-linked immunosorbent assay method, which does not distinguish tacrolimus from its metabolites. The rate of absorption of tacrolimus is variable with peak blood or plasma concentrations being reached in 0.5 to 6 hours; approximately 25% of the oral dose is bioavailable. Tacrolimus is extensively bound to red blood cells, with a mean blood to plasma ratio of about 15; albumin and alpha 1-acid glycoprotein appear to primarily bind tacrolimus in plasma. Tacrolimus is completely metabolised prior to elimination. The mean disposition half-life is 12 hours and the total body clearance based on blood concentration is approximately 0.06 L/h/kg. The elimination of tacrolimus is decreased in the presence of liver impairment and in the presence of several drugs. Various factors that contribute to the large inter- and interindividual variability in the pharmacokinetics of tacrolimus are reviewed here. Because of this variability, the narrow therapeutic index of tacrolimus, and the potential for several drug interactions, monitoring of tacrolimus blood concentrations is useful for optimisation of therapy and dosage regimen design.

Drug Interactions↗
PubMed1995

Selective labeling of the dopamine transporter by the high affinity ligand 3 beta-(4-[125I]iodophenyl)tropane-2 beta-carboxylic acid isopropyl ester.

The iodine-125 analog of the dopaminergically selective cocaine analog 3 beta-(4-iodophenyl)tropane-2 beta-carboxylic acid isopropyl ester (RT1-121) was evaluated as a probe for the dopamine transporter in rat striatum. Saturation and kinetic studies indicated that [125I]RTI-121 binds to both high and low affinity components. The Kd of the high affinity component was 0.14 +/- 0.01 nM (mean +/- standard error), whereas the low affinity component demonstrated an affinity of 1.59 +/- 0.09 nM. The corresponding numbers of striatal binding sites labeled by [125I]RTI-121 were 295 +/- 6 and 472 +/- 59 pmol/g of tissue (original wet weight), respectively. Intrastriatal injections of 6-hydroxydopamine eliminated > 90% of specific [125I]RTI-121 binding in the striatum. The pharmacological profile of specific [125I]RTI-121 binding in the rat striatum was consistent with that of the dopamine transporter. There was a strong (r = 0.98, p < 0.0001) correlation between the potencies of drugs that displaced specific [125I]RTI-121 binding and the potencies of these drugs to inhibit the uptake of [3H]dopamine. In contrast, no correlation was found for the potencies of drugs to inhibit the uptake of either [3H]norepinephrine or [3H]serotonin. Autoradiographs produced using [125I]RTI-121 demonstrated a distribution of label consistent with the distribution of dopaminergic neurons in rat brain. Because of its high affinity and high selectivity for the dopamine transporter, [125I]RTI-121 may be an extremely useful ligand for the dopamine transporter.

Animals↗
PubMed1993

FK506 measurement: comparison of different analytical methods.

In this study, we used solid-phase extraction with Sep-Pak and a liquid-liquid extraction with methylene chloride as two primary methods of extracting FK506 from plasma. The extracts were either analyzed directly by enzyme-linked immunosorbent assay (ELISA) or subjected to high-performance liquid chromatography (HPLC) separation and different fractions were analyzed by ELISA. Serial blood samples were obtained from four kidney transplant patients and four patients who underwent liver transplantation, from day 1 until day 30-35 posttransplantation. There was no significant difference in the FK506 plasma concentration as measured by all four methods in normal transplant patients. However, in liver transplant patients, the solid-phase extraction method gave higher FK506 concentrations than the methylene chloride extraction during the early postoperative period. The concentrations measured after methylene chloride extraction were higher than that after HPLC-ELISA. This higher FK506 concentration measured by direct ELISA could be attributed to possible cross-reacting metabolites that were present in the plasma of patients with abnormal liver functions. Once liver function returns to normal, all four methods give identical plasma concentrations for FK506.

Chemistry Techniques, Analytical↗
PubMed1992

A cocaine analog and a GBR analog label the same protein in rat striatal membranes.

Because some evidence suggests that cocaine and GBR12935 bind to different sites, we utilized photoaffinity probes from both classes of compounds to see if they label the same protein. [125I]RTI-82 a cocaine analog, and [125I]DEEP, a GBR analog, labeled protein(s) showing the same molecular weight, a similar pharmacological profile and a similar sensitivity to neuraminidase.

Animals↗
PubMed1991

Clinical significance of primitive reflexes in Alzheimer's disease.

STUDY OBJECTIVE: To establish the relationship between cognition, behavior, function, and clinical characteristics on the one hand, and the presence of primitive reflexes (PR) (pout, snout, palmomental and grasp) in patients with Alzheimer's disease (AD). DESIGN: Cross-sectional survey. SETTING: Secondary care geriatric practice specializing in the assessment of cognitive impairment. SUBJECTS: 136 consecutive patients presenting with AD. MEASUREMENTS: PR were assessed in standardized fashion by a single clinician. Cognitive function was measured using the Standardized Mini-Mental Status Examination, activities of daily living (ADL) and instrumental activities of daily living (IADL) were measured using the Lawton scale, and behavior was measured using the Behavioural Problem Checklist. RESULTS: There was no difference in age or duration of dementia in those with and without PR, nor was there any difference in cognitive function. Despite this, patients with PR showed a greater degree of functional limitation and dysfunctional behavior. There was also a higher incidence of rigidity, gait abnormalities, and apraxia in patients with PR. CONCLUSIONS: Patients with primitive reflexes had more severe impairment in ADL function and dysfunctional behavior for an equal level of cognitive function.

Activities of Daily Living↗
PubMed1990

Malignant cell autolysis caused by intracytoplasmic liberation of lysosomal enzymes.

An ultrastructural study of the action of peptidoglycans on malignant lymphocytes was made. Glycans acted upon lysosomes labilizing and rupturing the lysosomal membrane. Lysosomal enzymes were discharged directly into the cell cytoplasm. Nucleus, mitochondria and all organelles were digested in situ, resulting in a completely structureless cell. Finally, cancerous cells disintegrated by the detachment of cytoplasmic fragments.

Animals↗
PubMed1989

Eye injuries associated with 'war games'.

Eye injuries sustained by 4 patients who took part in 'war games' (in which young men shoot at each other with pistols powered by compressed carbon dioxide and firing latex rubber bullets filled with non-toxic paint) are described. In 3 cases the injuries were severe, including traumatic cataract, and 1 of these patients has a permanent macula scar with vision reduced to 6/36. Although eye protection is recommended, it was found that in the 'battle situation' combatants did not always follow regulations. Attention is drawn to the seriousness of disregarding the need for correct protective glasses.

Adolescent↗
PubMed1977

Purine and pyrimidine nucleotides in some mutant human lymphoblasts.

To study the role of purine ribonucleotides as possible regulators of the rate of de novo purine biosynthesis in living human cells, we measured intracellular ribonucleotide concentrations by high-pressure liquid chromatography in a series of cloned human lymphoblast mutants selected by resistance to 8-azaguanine, in which the severity of hypoxanthine-guanine phosphoribosyltransferase (HGPRT) deficiency could be correlated with increases in the rate of de novo purine biosynthesis and increases in intracellular concentrations of phosphoribosyl pyrophosphate (PP-ribose-P). Compared with appropriate normal controls, intracellular purine ribonucleotide concentrations were not reduced in HGPRT-deficient lymphoblasts but there were striking increases in intracellular concentrations of some pyrimidine nucleotides and nucleotide sugars which appeared to be related to the degree of the deficiency. Similar changes were found in lymphoblasts from a Lesch-Nyhan boy. These data support the hypothesis that the accelerated rate of purine biosynthesis in HGPRT-deficient cells result from increases in intracellular PP-ribose-P concentration and not from changes in intracellular purine ribonucleotide concentrations. The possibility that the abnormality of pyrimidine nucleotide metabolism results from coordinate regulation of purine and pyrimidine biosynthesis by PP-ribose-P was not substantiated by measurement of rates of pyrimidine synthesis and experimental elevation of intracellular concentrations of PP-ribose-P after incubation of cells with inorganic phosphate.

Adenine Nucleotides↗
PubMed1977

Purine and pyrimidine nucleotide concentrations in cells with decreased hypoxanthine-guanine-phosphoribosyltransferase (HGPRT) activity.

1. In order to investigate the role of purine ribonucleotides in the regulation of de novo purine synthesis in living human cells deficient in HGPRT, intracellular ribonucleotide concentrations have been measured in HGPRT lymphoblasts, fibroblasts and erythrocytes and in appropriate HGPRT controls by high pressure liquid chromatography. 2. Purine Purine ribonucleotide concentrations were not reduced in HGPRT cells, supporting the hypothesis that accelerated purine biosynthesis de novo results from increased availability of PP-ribose-P and not from altered feedback regulation by purine ribonucleotides in HGPRT deficient cells. 3. Striking increases in intracellular concentrations of some pyrimidine nucleotides and nucleotide sugars were detected in HGPRT lymphoblasts and erythrocytes, but not in fibroblasts. 4. The possibiiity that this abnormality of pyrimidine metabolism might result from coordinate regulation of purine and pyrimidine synthesis de novo by PP-ribose-P was not substantiated by measurements of rates of pyrimidine synthesis and experimental elevation of intracellular concentrations of PP-ribose-P following incubation of cells with inorganic phosphate.

Cell Line↗