A potentially fatal drug reaction.
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Anticonvulsants↗
Biomedical subjects
D Patel
Publications and source records attributed to D Patel.
Valproate as an antidepressant in major depressive disorder.
Thirty-three outpatients who met DSM-IV criteria for major depressive disorder (MDD) with no history of manic or hypomanic symptomatology were enrolled in an 8-week open trial of valproate. By Week 4, 15 of the 28 completers (54%) demonstrated a significant clinical response as defined by a score reduction of 50 percent or more or a total score of 9 or lower on the Hamilton Rating Scale for Depression (HRSD). Mean HRSD scores of the completers decreased 48.8 percent at Week 4 (p < .0001). At Week 8, 19 of the 22 completers (86%) showed a significant response. Mean HRSD scores decreased from 22 +/- 5 at baseline to 7 +/- 4 at Week 8 (p < .0001). With the intent-to-treat analysis at Week 8, 66 percent were responders, and total group mean HRSD scores decreased 55 percent (p < .0001). The data suggest that valproate may be an effective treatment for MDD. Double-blind, placebo-controlled trials are needed to further document its efficacy in the treatment of MDD.
Adult↗
Validation of retroviral detection for rodent cell-derived products and gene therapy applications.
The availability of sensitive assays for detecting infectious murine retroviruses has become critical for the development and acceptance of a number of biopharmaceuticals, including monoclonal antibody-derived products and gene therapy vectors. Comparative studies demonstrated that the PG4 S+L- retrovirus infectivity test routinely yields higher titres than the mink cell test for xenotropic, amphotrophic and MCF murine retroviruses. A validation study for the PG4 S+L- assay demonstrated very good linearity (r2 of 0.95 to 0.99), reproducibility within a study (+/-0.35 log10 units), and precision between tests (+/-0.45 log10 units). Interference (or selectivity) in the presence of a non-specific antibody was insignificant (less than 0.2 log10 units). Sensitivity levels established from measurements as virus titres approach zero demonstrated a threshold value of 2-3 focus forming units (FFU)/ml. Two methods for increasing assay sensitivity were used including: (i) increased product samplings combined with a Poisson distribution analysis, and (ii) a 14-day co-cultivation with Mus dunni cells. Each of these methods was shown to increase sensitivity by at least one log10 unit. Murine retroviruses may also be detected by a less sensitive immunofluorescence assay (IFA) using specific monoclonal antibodies; this assay is essential for detecting certain recombinant ecotropic MuLVs. In summary, murine retroviral detection ranked by sensitivity is mink S+L- < IFA with monoclonal antibodies < PG4 S+L- < Mus dunni co-cultivation followed by PG4 S+L-.
Animals↗
Separation of T and B lymphocytes from human peripheral blood mononuclear cells using density perturbation methods.
The fractionation of sub-populations of peripheral blood mononuclear cells has become an essential routine procedure and some of the main fractionation methods used today are immunomagnetic separations. We describe a less expensive method for the separation of subpopulations of mononuclear cells using density perturbation, which uses the binding of antibody-coated dense polystyrene beads to increase the density of specific sub-populations of cells. By incubating a total mononuclear fraction from human peripheral blood together with antibody-coated beads, in a commercially-available lymphocyte separation medium (Nycoprep 1.077), a depletion of 94.9 +/- 1.68% of the T cells could be obtained by this procedure; a depletion of 69.7 +/- 1.78% of the B cells was also achieved. These results indicate the potential for the separation of different sub-populations of peripheral blood mononuclear cells on the basis of the immunological identity of the surface of cells using density perturbation methods involving antibody-coated dense polystyrene beads.
Antibodies, Monoclonal↗
Synthesis and biological evaluation of 14-alkoxymorphinans. 11. 3-Hydroxycyprodime and analogues: opioid antagonist profile in comparison to cyprodime.
A series of 3-hydroxy-substituted analogues (3-7) of the mu selective opioid antagonist cyprodime has been synthesized in order to evaluate the role of a hydroxy group at C-3 concerning mu opioid antagonist selectivity. Compounds 3-7 were tested in bioassays (electrical stimulated mouse vas deferens preparation and myenteric-plexus longitudinal muscle preparation of the guinea pig ileum) and opioid receptor binding assays. Antagonism of mu receptor-mediated responses induced by the mu selective agonist DAMGO afforded equilibrium dissociation constants in the mouse vas deferens preparation (Ke values) for compounds 3-7 which agreed closely with their affinities as determined by opioid receptor binding assays (Ki values). At kappa and delta receptors differences were apparent. Although the compounds had high affinity for both kappa and delta receptors in opioid receptor binding, they were very poor at antagonizing agonist responses mediated by kappa and particularly delta agonists in the mouse vas deferens preparation. None of the compounds tested showed agonist potency in the mouse vas deferens preparation or the myenteric-plexus longitudinal muscle preparation of the guinea pig ileum.
Animals↗
Optimization of conditions for specific binding of antibody-coated beads to cells.
It has previously been demonstrated that cells can bind antibody-coated beads; this effect can be used to enhance the fractionation of cells using magnetic fields or by centrifugation on isopycnic, isotonic density gradients. As a general rule, the higher the expression of surface antigens the more beads bind to cells. However, we have also noted that other factors also affect the number of beads found bound to cells. Experiments have been carried out to determine what factors affect binding of antibody-coated beads to cells. The optimum conditions for binding of antibody-coated beads to MOLT-4 T cells were found to be, namely, a 20:1 bead to cell ratio in a 1 ml incubation volume, with continuous end-over-end mixing for 1 h at 25 degrees C. Furthermore, the optimum centrifugation conditions at which the samples were separated on isopycnic, isotonic density gradients were determined as 220 x gmax for 90 min, at 20 degrees C. The results indicate the preferred conditions that are necessary to achieve optimum bead binding by cells and their subsequent fractionation. Different antibody-coated beads were examined including Dynabeads M-450, used as a known standard. In addition we describe, as a possible alternative to Dynabeads, dense polystyrene beads, for the separation of cells on the basis of the immunological identity of the surface of cells using density perturbation methods.
Animals↗
Bisubstrate inhibitors of farnesyltransferase: a novel class of specific inhibitors of ras transformed cells.
We describe the biological properties of a new class of potent farnesyltransferase (FT) inhibitors designed as bisubstrate analog inhibitors. These inhibitors incorporate the structural motifs of both farnesyl pyrophosphate and the CAAX tetrapeptide, the two substrates of the reaction catalyzed by FT. Both the phosphinate inhibitor, BMS-185878, and the phosphonate inhibitor, BMS-184467, exhibited higher in vitro FT selectivity than some of the previously reported CVFM peptidomimentics and benzodiazepine analogs. Xenopus oocyte maturation induced by microinjected oncogenic Ras proteins was blocked by coinjected BMS-184467 and BMS-185878. However, both inhibitors showed poor cell activity presumably because of the doubly charged nature of the compounds. Thus, masking the charge on the carboxylate ion markedly improved the cell permeability of BMS-185878, leading to BMS-186511, the methyl carboxyl ester prodrug. BMS-186511 inhibited FT activity in whole cells as determined by inhibition of p21 Ras protein processing, inhibition of farnesylation of proteins including Ras and the accumulation of unfarnesylated Ras proteins in the cytosolic fraction. While the cellular effects of these bisubstrate analog inhibitors had no significant effect on growth of untransformed NIH3T3 cells, they produced pronounced inhibition of Ras transformed cell growth. Both the anchorage dependent and independent growth of ras transformed cells were severely curtailed by micromolar concentrations of BMS-186511. We also found that both H-ras and K-ras transformed cells are affected by this bisubstrate inhibitor. However, K-ras transformed cells appear to be less sensitive. The inhibition of FT activity in cells and the ensuing inhibition of ras transformed cell growth is further manifested in distinct morphological changes in cells. Cells flattened, became less refractile and grew in contact inhibited monolayer. Moreover, the highly diffused character of the actin cytoskeleton in the ras transformed cells was dramatically reverted to an organized network of stress cables crisscrossing the entire cells upon treatment with BMS-186511. All of these effects of BMS-186511 are limited to ras transformed cells that utilize farnesylated Ras, but are not seen in transformed cells that use geranylgeranyl Ras or myristoyl Ras. Significantly, these FT inhibitors did not produce any signs of gross cytotoxicity in untransformed, ras transformed cells or other oncogene transformed cells.
3T3 Cells↗
Evolutionary origins of apoB mRNA editing: catalysis by a cytidine deaminase that has acquired a novel RNA-binding motif at its active site.
The site-specific C to U editing of apolipoprotein B100 (apoB100) mRNA requires a 27 kDa protein (p27) with homology to cytidine deaminase. Here, we show that p27 is a zinc-containing deaminase, which operates catalytically like the E. coli enzyme that acts on monomeric substrate. In contrast with the bacterial enzyme that does not bind RNA, p27 interacts with its polymeric apoB mRNA substrate at AU sequences adjacent to the editing site. This interaction is necessary for editing. RNA binding is mediated through amino acid residues involved in zinc coordination, in proton shuttling, and in forming the alpha beta alpha structure that encompasses the active site. However, certain mutations that inactivate the enzyme do not affect RNA binding. Thus, RNA binding does not require a catalytically active site. The acquisition of polymeric substrate binding provides a route for the evolution of this editing enzyme from one that acts on monomeric substrates.
APOBEC-1 Deaminase↗
Studies of hepatic warm ischemia in the obese Zucker rat.
The effects of warm ischemia were investigated in obese Zucker rats with severe hepatic steatosis in order to develop a nontransplant fatty liver ischemia model. Obese (Ob) and lean (Ln) Zucker rats were subjected to in vivo partial hepatic warm ischemia of 45 or 90 min. Injury was assessed by serum alanine aminotransferase, animal survival, and liver histology. Liver lipids were quantified in control animals. After 90-min ischemia and 2-hr reperfusion, liver malondialdehyde was measured and neutrophils in 12 microscopic fields were counted after esterase staining. After 45 and 90 min of ischemia, Ob animals had significantly higher alanine aminotransferase at 1-hr and 24-hr reperfusion, compared with Ln animals (P < 0.01). After 90 min of ischemia, none of the Ln and 8/9 Ob animals died within 48 hr (P < 0.01). Histologically, Ob animals had more hepatocyte necrosis than did Ln animals. Hepatic neutral and phospholipid content (mg/g) in Ob versus Ln animals was 45.2 +/- 2.6 versus 8.2 +/- 0.7 (P < 0.01) and 36.2 +/- 1.9 versus 27 +/- 2.2 (P < 0.05), respectively. After reperfusion, liver malondialdehyde content increased significantly in Ob animals (8.5 +/- 0.4 vs. 12.3 +/- 0.8 pM/mg protein; P < 0.05), but not in Ln animals. Neutrophils, scant in control livers, increased significantly (P < 0.01) after ischemia/RP, but it increased to a similar degree in Ob and Ln animals. Obese Zucker rats with hepatic steatosis are more susceptible to warm ischemia/reperfusion injury than lean animals, and lipid peroxidation may be an important contributory mechanism. Further studies in this model might help to investigate the human problem.
Alanine Transaminase↗
Detection of ambulatory ischaemia is not of practical clinical value in the routine management of patients with stable angina. A long-term follow-up study.
It has been reported that medically treated patients with stable angina and positive exercise test for ischaemia have an adverse 1-2 year outlook if they are shown also to have transient, and predominantly silent, ischaemic episodes detected by ambulatory ST segment monitoring during their daily activities: it has been suggested that this investigation could be used to identify patients more likely to benefit from early investigation and treatment. We assessed the long-term (up to 65 months) prognostic significance of transient ischaemic episodes during daily activities in 172 patients routinely attending cardiac outpatients with medically treated stable angina who had undergone exercise testing and 48 h of ambulatory ST segment monitoring between February 1988 and August 1989 for this purpose. A positive exercise test for ischaemia was not a prerequisite for inclusion. One hundred and four patients (60.5%) had a positive exercise test for ischaemia and 72 (42%) had transient ischaemia during daily activities (63 had both tests positive). Over a median 50-month follow-up period 54 patients suffered at least one cardiac event (primary event: cardiac death n = 7; non-fatal myocardial infarction n = 11; unstable angina n = 18; elective CABG/PTCA n = 18). Two further patients suffered non-cardiac death. Cardiac events, either objective (cardiac death or non-fatal myocardial infarction) or subjective (unstable angina or revascularisation) were no more likely to occur in those with transient ischaemia during daily life when compared with those without, at follow-up times up to 65 months.(ABSTRACT TRUNCATED AT 250 WORDS)
Adult↗
Effect of the StuI polymorphism in the LDL receptor gene (Ala 370 to Thr) on lipid levels in healthy individuals.
We have examined the effect on plasma lipid levels of a single base change in exon 8 of the LDL receptor gene that causes an amino acid change Ala 370 to Thr in a sample of 318 Icelandic individuals selected at random from the general population. The change destroys a StuI restriction site and was detected by digestion of pooled samples in groups of 5. The frequency of the loss of the cutting site was 0.05 (95% CI = 0.014-0.054). In men, those with the Thr allele (n = 18) had 8.3% higher total cholesterol, 11.8% higher LDL cholesterol and 10.3% higher apolipoprotein B than those with the common Ala allele, whereas in women those with the Thr allele (n = 12) had levels lower by 7.4%, 13.3% and 10.1% respectively. These differences reached statistical significance only in the men (p < 0.05). Functional analysis of CHO cells transfected with constructs of the LDL receptor cDNA carrying the Ala370 and Thr370 alleles showed that within the limits of the assays there was no difference in function of the LDL receptor protein as measured by uptake and degradation of LDL. The data raise the possibility that amino acid substitutions that could affect LDL receptor function below the limits of detection by conventional assays, may have an effect on plasma lipid levels in the general population.
Adolescent↗
Contrasting structural impacts induced by cis-syn cyclobutane dimer and (6-4) adduct in DNA duplex decamers: implication in mutagenesis and repair activity.
The relative biological importance of cis--syn cyclobutane dimer and pyrimidine(6-4)pyrimidone photoadduct ([6-4] photoadduct) appears to be dependent on the biological species, dipyrimidine sites and local conformational variation induced at the damaged sites. The single-strained deoxynucleotide 10-mers containing the site-specific (6-4) adduct or cis--syn cyclobutane dimer of thymidylyl(3'-->5')-thymidine were generated by direct photolysis of d(CGCATTACGC) with UVC (220-260 nm) irradiation or UVB (260-320 nm) photosensitization. Three-dimensional structures of the duplex cis--syn and (6-4) decamers of d(CGCATTACGC)xd(GCGTAATGCG) were determined by NMR spectroscopy and the relaxation matrix refinement method. The NMR data and structural calculations establish that Watson-Crick base pairing is still intact at the cis--syn dimer site while the hydrogen bonding is absent at the 3'-side of the (6-4) lesion where the T-->C transition mutation is predominantly targeted. Overall conformation of the duplex cis--syn decamer was B-DNA and produced a 9 degree bending in the DNA helix, but a distinctive base orientation of the (6-4) lesion provided a structural basis leading to 44 degree helical bending. The observed local structure and conformational rigidity at the (6-4) adduct of the thymidylyl(3'-5')-thymidine (T-T [6-4]) lesion site suggest the potential absence of hydrogen bonding at the 3' sides of the (6-4) lesion with a substituted nucleotide during replication under SOS conditions. Contrasting structural distortions induced ny the T-T (6-4) adduct with respect to the T-T cis--syn cyclobutane pyrimidine photodimer may explain the large differences in mutation spectrum and repair activities between them.
Base Sequence↗
Acute and chronic response of articular cartilage to holmium:YAG laser irradiation.
A Ho:YAG (holmium-yttrium-aluminum-garnet) laser system operating at a wavelength of 2.1 microns has been introduced recently for use in arthroscopic surgery. The acceptability of this new tool will be determined not only by its ability to resect tissue, but also by its long-term effects on articular surfaces. Two studies were performed to evaluate the acute and chronic effects of the laser on cartilaginous tissue. The acute in vitro effects of 2.1-micron laser irradiation were evaluated, including measurement of ablation efficiency, ablation threshold, and thermal damage in meniscal and articular cartilage. To document the chronic effects on articular cartilage in vivo, a 10-week healing study was performed. Eight sheep weighing 30 to 40 kg underwent bilateral arthrotomy procedures. Multiple full-thickness and partial-thickness defects were created. Animals were euthanized at 0, 2, 4, and 10 weeks. The results of the healing study showed (1) no healing of full- or partial-thickness defects in hyaline cartilage at 10 weeks; (2) fibrocartilaginous granulation tissue filling full-thickness defects at 2 and 4 weeks that was no longer evident at 10 weeks; (3) chondrocyte necrosis extending to > 900 microns distal to ablation craters at 4 weeks, with no evidence of repair at later dates; (4) chondrocyte hyperplasia at the borders of the damage zone at 2 weeks but not at euthanization occurring at later periods.
Animals↗
Neurologic and developmental outcome in treated congenital toxoplasmosis.
BACKGROUND: Earlier studies have shown that infants with untreated congenital toxoplasmosis and generalized or neurologic abnormalities at presentation almost uniformly develop mental retardation, seizures, and spasticity. Children with untreated subclinical disease at birth have developed seizures, significant cognitive and motor deficits, and diminution in cognitive function over time. OBJECTIVE: To determine neurologic, cognitive, and motor outcomes for children with congenital toxoplasmosis who were treated for approximately 1 year with pyrimethamine and sulfadiazine. DESIGN AND METHODS: Systematic, prospective, and longitudinal neurologic, cognitive, and motor evaluations were performed for 36 individuals with congenital toxoplasmosis. These infants were born between December 1981 and January 1991 and were treated with pyrimethamine and sulfadiazine for approximately 1 year beginning in the first months of life. Compliance with medications was documented. These individuals were evaluated in a standardized manner in a single center in the first months of life and at approximately 1, 3.5, 5, 7.5, and 10 years of age. Their cognitive function was compared with the cognitive function of a nearest-age, same-sex sibling when such siblings older than 3.5 years were available for study. RESULTS: Signs of active central nervous system infection (eg, cerebrospinal fluid [CSF] pleiocytosis, hypoglycorrhachia, elevated CSF protein, and, in some instances, seizures and motor abnormalities) resolved during therapy. Six of the 36 children had perinatal seizures. Four had their anticonvulsant therapy discontinued successfully within the first months of life, and two additional children developed new seizures at 3 and 5 years of age. Tone and motor abnormalities resolved by 1 year of age in 12 of 20 infants who exhibited abnormalities of tone and motor function at their initial neonatal evaluation. By February 1992, 29 of the 36 children had been evaluated when they were 1 year old, and 23 (79%) had a mean +/- standard deviation Mental Developmental Index (MDI) of 102 +/- 22 (range, 59 to 140). Six (21%) had a measure of their cognitive function that was less than 50. Results of sequential IQ tests, performed at 1.5 year intervals or greater, did not differ significantly over time (P > .05). Seven children with MDIs greater than 50 were compared with sibling controls; they had scores of 87 +/- 11 (range, 68 to 97) and their siblings had scores of 112 +/- 15 (range, 85 to 132) (P = .008). Seventeen of 18 children without hydrocephalus and six of eight children with obstructive hydrocephalus responsive to shunting had normal or near-normal neurologic and developmental outcomes. Children with hydrocephalus ex vacuo present at birth, with high CSF protein, and with lack of response to shunting have done less well. CONCLUSIONS: Neurologic and developmental outcomes were significantly better for most of these treated children than outcomes reported for untreated children or those treated for only 1 month (P < .001). Although the level of cognitive function for treated children was less than for their uninfected siblings (P < .008), there was no significant deterioration in neurologic and cognitive function of the treated children tested sequentially. These favorable treatment outcomes justify systematic identification and treatment of pregnant women with acute gestational Toxoplasma infection and young infants with congenital toxoplasmosis.
Child Development↗
Clinical characteristics of black asthmatic children.
A prospective study of 455 black asthmatic children (277 boys) attending the Baragwanath Hospital asthma clinic was undertaken. A history was obtained by means of a standardised questionnaire and skin tests were performed. Cough was the commonest presenting symptom and upper respiratory tract infections, exercise and cold weather the commonest symptom precipitants. The relative incidences of the other precipitants reflected the environment of the study population. Associated atopic conditions were present in 75.5% of patients and a family background in 22.2%. Other respiratory diagnoses were commonly made, particularly tuberculosis, which was diagnosed in 7.4%. Fewer than one-third had no positive skin reaction. The commonest allergens were grasses, pollen and house-dust mites. The high proportion of house-dust mite sensitivity (44.2%) contradicts beliefs that they are rare at higher altitudes.
Adolescent↗
Hypoxaemia during paediatric dental anaesthesia in the community.
The object of this paper is to measure the incidence of hypoxaemia during paediatric dental anaesthesia in the community and thus support or refute the recommendations for monitoring in the Poswillo report. Fifty unpremedicated children, ASA grade 1, between the ages of 2 and 16 years undergoing general anaesthesia for teeth extraction were studied. Patients were anaesthetised with a standard anaesthetic which consisted of 30% oxygen in 70% nitrous oxide and supplemented with halothane. A pulse oximeter was used to measure the oxygen saturation continuously. A 12% incidence of hypoxaemia was recorded and a 32% incidence of a 5% fall in the oxygen saturation from the baseline. Three children became hypoxaemic during the operative period and three during the recovery period. Although the incidence of hypoxaemia in this study was significantly lower than in previous studies, the incidence suggests that careful monitoring is essential and the recommendations that have been put forward in the Poswillo report are fully justified.
Adolescent↗
Evidence that random and imprinted Xist expression is controlled by preemptive methylation.
The mouse Xist gene is expressed exclusively from the inactive X chromosome and may control the initiation of X inactivation. We show that in somatic tissues the 5' end of the silent Xist allele on the active X chromosome is fully methylated, while the expressed allele on the inactive X is completely unmethylated. In tissues that undergo imprinted paternal Xist expression and imprinted X inactivation, the paternal Xist allele is unmethylated, and the silent maternal allele is fully methylated. In the male germline, a developmentally regulated demethylation of Xist occurs at the onset of meiosis and is retained in mature spermatozoa. This may be the cause of imprinted expression of the paternal Xist allele. A role for methylation in the control of Xist expression is further supported by the finding that in differentiating embryonic stem cells during the initiation of X inactivation, differential methylation of Xist alleles precedes the onset of Xist expression.
Animals↗