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Biomedical subjects

J M Rowland

Publications and source records attributed to J M Rowland.

At least 19 recordsLinked to original sources
PubMed1993

Reverse transcriptase PCR amplification of EWS/FLI-1 fusion transcripts as a diagnostic test for peripheral primitive neuroectodermal tumors of childhood.

The peripheral primitive neuroectodermal tumors (pPNETs) of childhood, including Ewing's sarcoma, peripheral neuroepithelioma, and Askin's tumor, often present significant diagnostic challenges for the anatomic pathologist. One consistent feature of these tumors is the presence of the t(11;22)(q24;q12) in tumor cells, and this translocation has been useful as a marker for this group of tumors. The recent cloning of the t(11;22) breakpoint has revealed the fusion of the human FLI-1 gene on chromosome 11q24 with a gene of unknown function called EWS on 22q12, and fusion transcripts have been detected. These findings have raised the possibility of using molecular genetic analysis as a tool to diagnose pPNETs. To this end, we have tested pPNETs for the presence of EWS/FLI-1 fusion transcripts by reverse transcriptase-polymerase chain reaction (RT-PCR) using EWS and FLI-1 specific primers. Eight (80%) of 10 pPNET cell lines were positive for amplified products using this technique. These results were confirmed by Southern analysis, which revealed rearrangements of EWS using genomic EWS probes in all eight positive cell lines. We then tested 20 primary pPNET tumors, and identified fusion transcripts by RT-PCR in 18 (90%) of these cases. Cloning and sequencing of PCR products confirmed the presence of EWS and FLI-1 sequences in these products. Furthermore, fusion transcripts were not detected by this technique in a series of non-pPNET pediatric solid tumors. Detection of EWS/FLI-1 fusion transcripts by RT-PCR therefore provides a novel adjunctive tool in the diagnosis of pPNETs.

Adolescent↗
PubMed1992

Age-related marrow changes in the pelvis: MR and anatomic findings.

Short repetition time magnetic resonance images of the pelvis in 70 subjects (aged 1 day to 24 years) without history of bone marrow disease were retrospectively analyzed for the distribution and appearance of red and yellow marrow. The signal intensity and degree of mottling of marrow in six anatomic regions of the pelvis were observed and were assigned a grade. Anatomic correlation was provided with gross and microscopic examination of bone marrow biopsy specimens taken from selected pelvic sites in cadavers of children. Marrow signal intensity increased in all pelvic regions except the acetabulum from birth to age 24 years. Marrow heterogeneity was most prominent in the acetabulum at all ages. Patterns of bone marrow signal intensity and heterogeneity are recognized for four age groups: the infant, child, adolescent, and young adult. Regional and age-related differences in the signal intensity of pelvic marrow correlate with the percentage of fat seen microscopically in marrow.

Adolescent↗
PubMed1990

Differential inhibition of HIV-1 cell binding and HIV-1-induced syncytium formation by low molecular weight sulphated polysaccharides.

Dextran sulphate (MW 5000 and 8000) and a polysulphated glycosaminoglycan (MW 10,000), at concentrations that provided complete protection in a homologous infection assay, failed to block syncytium formation and the resulting cytopathic effect when MT-2 cells were mixed with H9/HIV-1 cells. These substances also had no antiviral activity when added to cells, after virus challenge, at a time when binding and entry were complete. However, a high molecular weight (500,000) dextran sulphate blocked HIV-1 infection at both stages. Thus, the gp120-CD4 interactions mediating HIV-1 binding and HIV-1-induced syncytium formation are differentially affected by this class of polyanionic substances. Furthermore, size may be a determining factor in their potential application as anti-HIV treatment.

Antiviral Agents↗
PubMed1990

Antifusion activity in sera from persons infected with human immunodeficiency virus type 1.

Cell-to-cell fusion plays an important role in the pathogenesis of human immunodeficiency virus type 1 (HIV-1) infections. An assay to measure the antifusion activity of serum has been developed by using the fusion event that occurs between H9 cells chronically infected with HIV-1 (H9IIIB) and fusion-susceptible MT-2 cells. The endpoint is determined by measuring neutral red uptake in cells after syncytium formation is allowed to occur in the presence of various serum dilutions. The assessment of antifusion activity in serum by neutral red uptake has been shown to correlate with syncytium reduction as determined by direct counting. The optimal number and ratio of cells in the suspension for efficiency and speed of the assay have been determined. With this assay it was shown that 50% of 36 serum specimens capable of neutralizing cell-free virions failed to inhibit syncytium formation. The assay can thus measure a distinct activity in HIV-1-immune human sera which is a subset of neutralization activity. Because of the potential role of this activity in the rate of disease progression and protective immune responses, the antifusion assay will be an important tool for the investigation of disease pathogenesis and for acquired immunodeficiency syndrome vaccine development. The assay can also be applied to the investigation of the pathogenesis of the fusion event at the cellular level. The ability to use absorbance measurements rather than syncytium counts as the endpoint facilitates direct computer-assisted data analysis, which expedites the performance of the assay.

Cell Fusion↗
PubMed1989

Pharmacokinetics of doxylamine given as Bendectin in the pregnant monkey and baboon.

The object of the present study was to determine the maternal plasma pharmacokinetics of doxylamine (the antihistamine component of Bendectin) following Bendectin administration. Bendectin was administered daily, po, at a dosage approximately 10 times the maximum human therapeutic dosage (7 mg/kg/day) throughout organogenesis (approximately days 22 through 50 of gestation) to three cynomolgus monkeys, four rhesus monkeys, and five baboons. Two pharmacokinetic experiments were performed in each animal, one on the first day of treatment and one on the last day of treatment. Although this study was not designed specifically as a teratologic examination, no morphologic abnormalities were observed when the fetuses were examined on approximately day 100 of gestation. A single-compartment, parallel first- and second-order elimination model was used to analyze the data. Although considerable interindividual variation was evident, no significant differences between species were observed when the half-life for the absorption of doxylamine from the gut or the elimination of doxylamine and metabolites from the plasma were compared. The plasma elimination half-lives and the clearance values were not altered by the 29 days of Bendectin treatment for any of the species. Only the half-life for the absorption of doxylamine in the baboon was reduced by daily dosing with Bendectin, but this did not alter doxylamine elimination. Thus, the pharmacokinetics of doxylamine administered as Bendectin were similar in the three nonhuman primate species examined and were not altered by repeated daily administration.

Animals↗
PubMed1988

Valproic acid developmental toxicity and pharmacokinetics in the rhesus monkey: an interspecies comparison.

This study was undertaken to assess the developmental toxicity and drug distributional and metabolic characteristics of prenatal valproic acid (VPA) exposure in rhesus monkeys. Oral administration of 20-600 mg/kg/day VPA (approximately 1-15 X human therapeutic dose) to 33 animals on variable gestational days (GD) during organogenesis resulted in dose-dependent developmental toxicity manifested as increased embryo/fetal mortality, intrauterine growth retardation, and craniofacial and skeletal defects. Biphasic plasma elimination curves were observed for total and free VPA on the first (GD 21) and last (GD 50) days of treatment in the 100- and 200-mg/kg/day dose groups. VPA exhibited dose-independent elimination kinetics at the plasma concentrations observed in this study. There was no significant change in pharmacokinetic parameters (maternal plasma elimination rate, area under the curve, peak plasma concentration) between the first and last days of treatment at either dose level. Placental transfer studies indicated that embryos were exposed to half the free VPA concentrations present in maternal plasma on GD 37. Comparisons of interspecies sensitivity to VPA-induced developmental toxicity in the mouse, rat, monkey, and man are made.

Abnormalities, Drug-Induced↗
PubMed1988

Evaluation of valproic acid (VPA) developmental toxicity and pharmacokinetics in Sprague-Dawley rats.

This study was undertaken to assess the pharmacokinetics and developmental toxicity of the anticonvulsant, valproic acid (VPA), a human teratogen, in Sprague-Dawley rats. Oral administration of 200-800 mg/kg VPA (5-20x human therapeutic dose) from Gestational Days (GD) 8 to 17 resulted in increasing maternal toxicity at the higher doses with 100% maternal lethality at 800 mg/kg. Although there was an increased incidence of resorptions at 600 mg/kg (48 +/- 43%) compared to controls (18 +/- 24%), it was not statistically significant. Fetal examination on GD 20 revealed dose-dependent fetal growth retardation (p less than or equal to 0.05) as evidenced by decreased fetal weight and length in addition to underossification of both the axial and appendicular skeleton. The incidence of skeletal defects, including abnormal vertebrae, ribs, and craniofacial dysmorphia, also increased with higher doses of VPA. Cardiac anomalies observed in the two highest treatment groups consisted of great vessel malformations with or without associated ventricular septal defects (VSDs). Urogenital defects were also noted in the 600 mg/kg group. The plasma elimination half-life on GD 8 was 1.0 +/- 0.3 hr at 200 mg/kg and 2.3 +/- 0.7 hr at 600 mg/kg. Maximal concentrations of total and free drug were 341 +/- 18 micrograms/ml and 181 +/- 11 micrograms/ml, respectively, in the low-dose group and 911 +/- 379 micrograms/ml and 542 +/- 224 micrograms/ml in the high-dose group. No significant changes in any pharmacokinetic parameters (t1/2, AUC, Cmax, tmax) were observed over the 10-day treatment period at either dose level.

Administration, Oral↗
PubMed1987

Evaluation of the teratogenicity and pharmacokinetics of diflunisal in cynomolgus monkeys.

This study examined the pharmacokinetics and potential teratogenicity of the nonsteroidal antiinflammatory drug, diflunisal, in cynomolgus monkeys. Pregnant cynomolgus monkeys were administered 0.5% methyl cellulose, 20 mg/kg/day diflunisal, or 80 mg/kg/day diflunisal on Days 25 to 48 of gestation. There was no evidence of maternal toxicity, increased abortion rate, fetal growth retardation, or malformation. These data demonstrate that diflunisal is not teratogenic in cynomolgus monkeys over a dosage range of 20 to 80 mg/kg/day. Peak plasma levels of diflunisal were found 1 hr after oral administration of [14C]diflunisal at a dosage of 60 mg/kg and declined to low levels by 24 hr. The plasma elimination half-life was calculated to be 10.2 hr over the period of 1 to 8 hr postadministration. Intact diflunisal accounted for 96.4% of total plasma radioactivity at 0.5 hr and declined to a value of 74% at 8 hr. Plasma protein binding averaged greater than 99% over a concentration range of 62.5 to 250 micrograms/ml. Urinary excretion of diflunisal and metabolites averaged 66.5% of the dosage over the first 4 days postadministration, compared with 0.8% in the feces. The majority of activity represented conjugates of diflunisal. Embryo concentrations of diflunisal on Days 35 to 37 of gestation were 0.7 and 1.1% of maternal plasma level at 4 hr postadministration of 20 or 60 mg/kg, respectively.

Abnormalities, Drug-Induced↗
PubMed1986

Effects of ibuterol, a beta-2 adrenergic prodrug, on intraocular pressure.

Ibuterol, a prodrug of terbutaline, was approximately 100 times more potent than terbutaline in producing ocular hypotension in the treated eye of normal and sympathectomized (SX) rabbits. In normal rabbits, ibuterol produced no change in IOP of the contralateral eye whereas in unilaterally SX rabbits a rise in IOP occurred in the SX (contralateral) eye when the normal eye was treated with ibuterol. Ibuterol also suppressed ocular hypertension induced by water loading and delayed the IOP recovery rate although its onset of action was delayed. Aqueous flow was increased significantly at 1 hr after ibuterol in fluorophotometric studies in normal rabbits. Pretreatment with forskolin antagonized rather than enhanced ibuterol-induced ocular hypotension. Pretreatment with diclofenac failed to suppress the development of tachyphylaxis to the ocular hypotensive effect of ibuterol. Although ibuterol is an effective ocular hypotensive agent in rabbits, the effects of this agent on aqueous flow are complex and tachyphylaxis to the ocular hypotensive effect develops fairly rapidly.

Animals↗
PubMed1986

Effects of topical diclofenac sodium in a rabbit model of ocular inflammation and leukotaxis.

A useful model that combines paracentesis with administration of a leukotactic factor was developed in order to study the effects of topical diclofenac sodium on various aspects of ocular inflammation. The increases in intraocular pressure (IOP) and secondary aqueous humor protein concentration induced in rabbits by anterior chamber paracentesis, as well as leukocyte accumulation in the anterior chamber induced by formyl-methionyl-leucyl-phenylalanine, were significantly reduced by topical application of diclofenac sodium at concentrations of 2 mM (0.064%, w/v) and higher. Lower doses consistently affected only IOP and secondary protein concentrations. A slight paracentesis-induced miosis was refractory to diclofenac sodium. That this potent inhibitor of prostaglandin synthesis can reduce important signs of ocular inflammation is well supported in this model.

Administration, Topical↗
PubMed1986

Studies on the circadian rhythm of IOP in rabbits: correlation with aqueous inflow and cAMP content.

We investigated the relationship of aqueous humor inflow rate and cyclic AMP concentrations to the spontaneous and dramatic changes in IOP associated with onset of darkness in our previously described model of circadian rhythm of intraocular pressure. After onset of darkness, rabbits entrained in an environment with a daily alternating cycle of 12 hours light and 12 hours darkness (12L:12D) showed an 85% increase in outflow pressure, a nearly 60% increase in aqueous inflow rate and an 80% increase in aqueous cAMP. Animals desynchronized by an unpredictable light cycle showed no increase in IOP or inflow rate when measured at the same time intervals as were the entrained animals. Thus, the IOP, aqueous inflow rate and aqueous cAMP are all seen to change in the same direction in a pharmacologically unperturbed rabbit eye. Previous pharmacological studies in rabbits have correlated an increase in cAMP with a decrease in IOP and aqueous inflow.

Animals↗
PubMed1984

Comparison of the metabolism of cortisol and triamcinolone acetonide in the early, mid, and late gestational age rhesus monkey (Macaca mulatta).

The metabolism of radiolabeled cortisol and triamcinolone acetonide (TAC) was compared in the early, middle, and late gestational age rhesus monkeys. Trace amounts of 14C-cortisol and 10 mg/kg 3H-TAC (Kenalog) were simultaneously administered i.m. to the maternal animal. Whole 30-day embryos or 61- to 137-day fetal organs, amniotic fluid, and placenta were collected from 0.5 to 24 h after dose administration and analyzed by high-performance liquid chromatography (HPLC). Serial blood samples collected from all maternal animals and the late gestational age fetuses were similarly processed. The maternal plasma concentration of total radioactivity derived from TAC 1-60 min after dose administration was significantly less on day 30 of gestation as compared to day 60 at the 5-, 10-, and 60-min time points. At 60 and 130 days of gestation, however, the maternal plasma concentrations of total radioactivity were similar. Concentrations of cortisol-derived radioactivity in the maternal plasma were the same across gestational age. The plasma TAC and cortisol metabolic profiles, as determined by HPLC, were not significantly different throughout pregnancy. In late pregnancy 30 min after dose administration, the fetal to maternal plasma cortisol ratio was 0.34, whereas the same ratio for TAC was 0.96. By 1 h after dose administration, less than 8% of the total 14C radioactivity in fetal tissues was cortisol and over 92% of the 3H was TAC. The extensive fetoplacental metabolism of cortisol to inactive metabolites and the resistance of TAC to metabolic conversion results in greater TAC than cortisol exposure of the developing rhesus monkey conceptus.

Animals↗
PubMed1983

Comparative teratogenicity of triamcinolone acetonide, triamcinolone, and cortisol in the rat.

Pregnant rats were injected im with 0.5 mg/kg triamcinolone acetonide (TAC) on day 12, 13, or 14 of gestation and the fetuses were examined for cleft palate on day 20. All three TAC-treated groups showed an increased proportion of fetuses with cleft palate compared to an untreated control group. Only the group treated on day 13 showed a significant increase in the proportion of litters affected. This indicates that day 13 of gestation is the most sensitive day for cleft palate induction by TAC in the rat. Pregnant rats were then treated on day 13 of gestation with either TAC, triamcinolone (TA), or cortisol. TAC was 59 times as potent as TA in inducing cleft palate, with ED50 values of 1.1 mg/kg and 65 mg/kg respectively. Cortisol induced a significant increase in cleft palates at 500 mg/kg, but the efficacy of this compound was too low to calculate an ED50 and relative teratogenic potency value. Other developmental abnormalities including umbilical hernias, resorption, and fetal death resulted from TAC treatment. Fetal growth retardation was produced by all three compounds. The rank order of teratogenic potency was determined to be TAC greater than TA greater than cortisol.

Animals↗
PubMed1983

Comparative distribution and metabolism of triamcinolone acetonide and cortisol in the rat embryomaternal unit.

Triamcinolone acetonide (TAC) is teratogenic in rats while cortisol has been reported as not teratogenic. The objective of this investigation was to determine whether this difference in teratogenicity could be due to a difference in the metabolism and distribution of the parent compound in the embryomaternal unit. 3H-TAC and 14C-cortisol were administered intramuscularly to pregnant rats on day 12 of gestation. These dams were killed at each of the following time points after injection: 0.5, 1, 3, 6 and 24 hr. Maternal plasma and embryos were analyzed by high performance liquid chromatography (HPLC) and liquid scintillation counting. The plasma concentration of parent TAC was significantly greater than that for parent cortisol at all time points. The plasma elimination half-life for TAC, 86 min, was also calculated to be significantly longer than that for cortisol, 8 min. Furthermore, the percentage of total plasma radioactivity representing HPLC resolved TAC was much higher than that representing cortisol at all time points. The concentration of TAC in the embryos was significantly greater than for cortisol at all time points. The elimination half-life for unchanged TAC in the embryos was 142 min compared to 22 min for cortisol. The percentage of total radioactivity in the embryos representing unchanged TAC was similar to that found in maternal plasma while the percentage of total radioactivity representing unchanged cortisol was much lower than that found in maternal plasma. These findings support the hypothesis that differences in the distribution and metabolism of the parent compound are a critical factor in determining the teratogenicity of that compound.

Animals↗
PubMed1983

Distribution and metabolism of triamcinolone acetonide in the rat embryomaternal unit during a teratogenically sensitive period.

The distribution and metabolism of triamcinolone acetonide (TAC) in the rat embryomaternal unit were investigated during a teratogenically sensitive period. Pregnant rats (Day 12 of gestation) were injected im with 0.125 or 0.5 mg/kg [3H]TAC. Maternal plasma and embryos were collected at selected time points and analyzed by HPLC and liquid scintillation counting. No significant differences in the percentage of total radioactivity representing unchanged TAC, concentration of TAC, or its elimination half-life were detected in either plasma or embryos of the two dose groups. These results provide evidence that the metabolism and distribution of TAC in the rat embryomaternal unit are dose independent over this known teratogenic dose range. To determine whether multiple administration of TAC resulted in any alterations in maternal or embryonal exposure, the same parameters were evaluated following one (Day 12), two (Days 12 and 13), or three (Days 12, 13, and 14) injections of [3H]TAC (0.5 mg/kg, im). The only alterations detected were an increase in the percentage of total radioactivity in maternal plasma representing unchanged TAC at 1 hr following the second or third injection and an increase in the embryonal concentration of TAC at the same time points.

Abnormalities, Drug-Induced↗