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R Weeks

Publications and source records attributed to R Weeks.

At least 19 recordsLinked to original sources
PubMed1997

Isolation and expression of an isoform of human CDP-diacylglycerol synthase cDNA.

Phosphatidic acid (PA) is a phospholipid involved in signal transduction and in glycerolipid biosynthesis. CDP-diacylglycerol synthase (CDS) or CTP:phosphatidate cytidylyltransferase (EC 2.7.7.41) catalyzes the conversion of PA to CDP-diacylglycerol (CDP-DAG), an important precursor for the synthesis of phosphatidylinositol, phosphatidylglycerol, and cardiolipin. We describe in this study the isolation and characterization of a human cDNA clone that encodes amino acid sequences homologous to Escherichia coli, yeast, and Drosophila CDS sequences. Expression of this human cDNA under the control of a GAL1 promoter in a null cds1 mutant yeast strain complements its growth defect and produces CDS activity when induced with galactose. Transfection of this cDNA into mammalian cells leads to increased CDS activity in cell-free extracts using an in vitro assay that measures the conversion of [alpha-32P]CTP to [32P]CDP-DAG. This increase in CDS activity also leads to increased secretion of tumor necrosis factor-alpha and interleukin-6 from endothelial ECV304 cells upon stimulation with interleukin-1beta, suggesting that CDS overexpression may amplify cellular signaling responses from cytokines.

Amino Acid Sequence↗
PubMed1996

Pharmacological inhibition of gelatinase B induction and tumor cell invasion.

The 92 kDa matrix metalloproteinase (gelatinase B, MMP-9) plays a major role in the facilitation of tumor metastasis and in inflammatory disorders characterized by excessive matrix protein destruction. MMP-9 is transcriptionally induced in multiple cell types by exposure to the inflammatory mediators bacterial endotoxin, interleukin-1 (IL-1) or tumor necrosis factor-alpha (TNF-alpha). CT-2519, (1-(5-isothiocyanatohexyl)-3,7-dimethylxanthine), a synthetic small molecule from an anti-inflammatory compound library, was evaluated for its effect on endotoxin and cytokine-induced MMP-9 synthesis by a monocytic leukemic cell line, THP-1, and a monocyte/macrophage line, RAW 264.7. CT-2519 dose-dependently inhibited endotoxin and cytokine-induced synthesis of MMP-9 by these cells. Furthermore, both MMP-9 secretion and matrix invasion by cells of a human fibrosarcoma cell line, HT-1080, were inhibited by CT-2519 in a dose-dependent manner. Northern blot analyses and studies utilizing MMP-9 promoter constructs indicated that the inhibitory action of CT-2519 occurs at the level of transcriptional suppression. Given the observation that cellular activation by endotoxin, IL-1 and TNF-alpha may be mediated, at least in part, through induction of certain species of phosphatidic acid (PA), the effect of CT-2519 on lipid levels was analyzed. CT-2519 effectively reduced endotoxin-mediated increases in particular cellular lipid levels. Pharmacologic modulation of cytokine-dependent gene products, such as MMP-9, may offer an important therapeutic approach to the treatment of neoplastic and inflammatory disorders.

Animals↗
PubMed1996

Analgesic rebound headache in clinical practice: data from a physician survey.

BACKGROUND: Frequent, excessive use of over-the-counter or prescription analgesics may lead to analgesic rebound headache. Little is known about the magnitude of the health problem posed by analgesic rebound headache, its epidemiology, the characteristics of analgesic rebound headache sufferers, or about physicians' approaches to treatment. METHODS: Four hundred seventy-three practitioners, who had previously expressed an interest in the treatment of headache, were mailed a questionnaire designed to capture information about the frequency and management of analgesic rebound headache and about the characteristics of analgesic rebound headache sufferers. RESULTS: Completed questionnaires were returned by 174 practitioners (37%) from 40 states, the District of Columbia, and Puerto Rico. More than 40% of respondents indicated that analgesic rebound headache was present in at least 20% of their patients. On average, the physicians reported that 73% of patients with analgesic rebound headache were women. Analgesic rebound headache was most likely to occur in patients aged 31 to 40 years. No one analgesic was consistently identified as causative, although acetaminophen, butalbital + aspirin + caffeine, and aspirin were commonly used by patients. Eighty percent of respondents indicated that depression was commonly observed in analgesic rebound headache sufferers; 77% indicated that physical conditions (especially gastrointestinal symptoms) were commonly observed. A variety of therapeutic strategies, including pharmacotherapy, were used in the management of analgesic rebound headache. CONCLUSION: Analgesic rebound headache was recognized as a distinct entity and a substantive component in more than 40% of the practices of 174 surveyed practitioners. General practitioners, who see a wide variety of patient types with a spectrum of complaints, need to be able to diagnose analgesic rebound headache by taking a good history.

Adult↗
PubMed1995

CT-2576, an inhibitor of phospholipid signaling, suppresses constitutive and induced expression of human immunodeficiency virus.

Viruses such as human immunodeficiency virus (HIV) require cellular activation for expression. Cellular activation in lymphoid cells is associated with augmented accumulation of certain phosphatidic acid (PA) species derived from the hydrolysis of glycan phosphatidylinositol (GPI). This suggests that activation of a phospholipid pathway may play a role in initiation of viral replication. To test this hypothesis, we examined the effect of tat gene expression on the production of cellular PA species, as the Tat protein is essential for HIV expression and has been implicated in activating the expression of multiple host cellular genes. Expression of tat increased the expression of PA. We then tested whether synthetic inhibitors of PA metabolism would inhibit activation of the HIV long terminal repeat by Tat and tumor necrosis factor alpha (TNF-alpha). CT-2576 suppressed both PA generation induced by Tat and HIV long terminal repeat-directed gene expression in response to Tat or TNF-alpha at a posttranscriptional step. CT-2576 also inhibited constitutive as well as TNF-alpha- and interleukin 6-induced expression of HIV p24 antigen in chronically infected U1 cells and in peripheral blood lymphocytes acutely infected with a clinical isolate of HIV. Pharmacological inhibition of synthesis of selected PA species may therefore provide a therapeutic approach to suppression of HIV replication.

Alkaline Phosphatase↗
PubMed1995

Striatal D1 and D2 receptor binding in patients with Huntington's disease and other choreas. A PET study.

We have used PET to study striatal D1 and D2 receptor binding in 10 patients with either the choreic or akinetic-rigid variants of Huntington's disease and in three patients with other causes of chorea. Background rigidity and bradykinesia in choreic patients were scored with a four-point scale. PET studies showed a severe and parallel reduction of both striatal D1 and D2 receptor binding in Huntington's disease patients irrespective of their predominant phenotype (mean reduction 60%). Huntington's disease patients with rigidity showed more pronounced reduction of striatal D1 and D2 binding compared with those without rigidity. A case of chorea associated with systemic lupus erythematosus had normal D2 binding. These results suggest that the presence of chorea per se may not be determined by alterations in striatal dopamine receptor binding, but that rigidity in Huntington's disease is associated with severe striatal D1 and D2 receptor loss.

Adult↗
PubMed1994

CT-1501R selectively inhibits induced inflammatory monokines in human whole blood ex vivo.

The effect of (R)-1-(5-hydroxyhexyl)-3,7-dimethylxanthine (CT-1501R; the nonproprietary name for CT-1501R approved by the United States Name Council is lisofylline), an inhibitor of second messenger signaling through phosphatidic acid, on release of endogenous mediators important in the systemic inflammatory response syndrome (SIRS) was studied using the human whole blood ex vivo assay system. Human blood was stimulated with various endotoxin preparations, zymosan, or protein A, and the levels of secreted monokines were measured by enzyme-linked immunosorbent assay. CT-1501R inhibited tumor necrosis factor alpha (TNF-alpha), interleukin 1 beta (IL-1 beta), and IL-6 release in a dose-dependent manner and was active with all stimuli tested including Salmonella and Escherichia coli-derived endotoxin, endotoxin from both rough and smooth E. coli strains, as well as zymosan and protein A. CT-1501R inhibited monokine release by approximately 50% at 200 microM and 30% at 50 microM and was independent of the relative potency of stimulus. CT-1501R also inhibited IL-1 alpha or IL-1 beta induction of either TNF-alpha or IL-1 beta and inhibited the synergistic effects of stimulation with both human IL-1 beta and murine TNF-alpha on release of human TNF-alpha. Inhibition of monokine release following stimulation with monokine(s) was, in general, greater than that achieved with lipopolysaccharide (LPS) stimulation. Northern blot analysis showed decreased mRNA accumulation of TNF-alpha and IL-1 beta in CT-1501R-treated samples following LPS stimulation suggesting that CT-1501R acts at least in part, at the pretranslational level. In contrast, CT-1501R does not inhibit LPS-stimulated IL-8 or IL-1 receptor antagonist (IL-1ra) release in human whole blood or IL-1 alpha-induced release of PGE2 in human foreskin fibroblast cells. These data suggest that CT-1501R may be of use for clinical intervention in SIRS.

3T3 Cells↗
PubMed1994

PET studies of the presynaptic and postsynaptic dopaminergic system in Tourette's syndrome.

Dysfunction of the dopaminergic pathway has been postulated to underlie the symptomatology of Tourette's syndrome. Presynaptic functional integrity of dopaminergic terminals was assessed with 18F-dopa PET in 10 patients with Tourette's syndrome, three of whom were drug free and seven of whom were on neuroleptic treatment. Dopamine D2 receptor site density was measured with 11C-raclopride PET in a further group of five drug free patients with Tourette's syndrome. Mean caudate and putamen 18F-dopa influx constants were similar in patients with Tourette's syndrome and controls, and there was no difference in striatal 18F-dopa uptake between the treated and untreated Tourette's syndrome groups. Mean caudate and putamen 11C-raclopride binding potentials in patients with Tourette's syndrome were also similar to control values. The findings suggest that striatal metabolism of exogenous levodopa and the density of striatal D2 receptors are both normal in patients with Tourette's syndrome and that Tourette's syndrome does not arise from a primary dysfunction of dopaminergic terminals.

Adolescent↗
PubMed1994

Potential role for phosphatidic acid in mediating the inflammatory responses to TNF alpha and IL-1 beta.

Tumor necrosis factor alpha (TNF alpha), interleukin 1 beta (IL-1 beta), and endotoxin (LPS) are potent pro-inflammatory mediators which induce multiple and diverse biological responses in a wide variety of cell types. However, these pro-inflammatory mediators also have significant overlap and redundancy in their biological effects. This suggests that there is significant diversity in second messenger signal transduction systems induced by these stimuli to explain the diversity in biological responses, as well as significant redundancy. Here we show that one such second messenger common to several proinflammatory stimuli may be phosphatidic acid (PA). Intracellular PA species, which may have intracellular signaling functions, are rapidly induced in P388 monocytic leukemia cells by TNF alpha, IL-1 beta, or LPS. These PA species vary according to the bond type (i.e., sn-1 ester vs. ether vs. vinyl ether), acyl chain length, and the degree of saturation in the sn-1 and sn-2 positions. Although PA itself may have direct second messenger activities, many of the PA species induced are converted to diacylglycerol species (DG), which are structurally distinct from the DGs generated by phosphatidylcholine-specific phospholipase C (PC-PLC). Lisofylline [(R)-1-(5-hydroxyhexyl)-3,7-dimethylxanthine; LSF] selectively inhibits generation of selected species of PA in P388 cells induced by TNF alpha, IL-1 beta or LPS. TNF alpha-induced sphingomyelin hydrolysis, PLC-mediated PC hydrolysis, and DG kinase-mediated PA formation or TNF alpha-induced NF-kappa B activation and apoptosis are not inhibited by LSF. LSF has a marked protective effect in a variety of acute inflammatory animal models that may be due to inhibition of this shared second messenger pathway involving PA.

Animals↗
PubMed1993

A double-blind placebo-controlled trial of intranasal capsaicin for cluster headache.

It has been suggested that treatment of cluster headache (CH) patients with topical capsaicin may desensitize sensory neurons by depleting the nerve terminals of substance P. We attempted to determine whether capsaicin is effective in aborting CH attacks. Patients in acute cluster were randomized to receive either capsaicin or placebo in the ipsilateral nostril for 7 days. Patients recorded the severity of each headache for 15 days. Headaches on days 8-15 of the study were significantly less severe in the capsaicin group vs the placebo group. There was also a significant decrease in headache severity in the capsaicin group on days 8-15 compared to days 1-7, but not in the placebo group. Episodic CH patients appeared to benefit more than chronic CH patients. These results indicate that intranasal capsaicin may provide a new therapeutic option for the treatment of this disease.

Capsaicin↗
PubMed1992

Molecular organization of Leishmania RNA virus 1.

The complete 5284-nucleotide sequence of the double-stranded RNA genome of Leishmania RNA virus 1 (LRV1) was determined and contains three open reading frames (ORFs) on the plus (+) (mRNA) strand. The predicted amino acid sequence of ORF3 has motifs characteristic of viral RNA-dependent RNA polymerases. ORF2, which may encode the major viral coat protein, overlaps ORF3 by 71 nucleotides, suggesting a +1 translational frameshift to produce a gag-pol type of fusion protein. Two alternative models for the frameshift are presented. The 5' splice leader sequence of kinetoplastid mRNAs is not in LRV1 RNA. This suggests that the 450-base region at the 5' end of the LRV1 (+)-strand, which contains ORF1 and is highly conserved among viral strains, does not encode protein but has a role in initiation of translation and/or RNA stability. The similarity of LRV1 genomic organization, replication cycle, and RNA-dependent RNA polymerase sequence to those of the yeast virus ScV L-A suggests a common ancestral origin. The possibility that LRV1 affects pathogenesis in leishmaniasis is intriguing.

Amino Acid Sequence↗
PubMed1992

LRV1 viral particles in Leishmania guyanensis contain double-stranded or single-stranded RNA.

The 32-nm-diameter spherical viral particles found in the cytoplasm of Leishmania guyanensis CUMC1-1A sediment at 130S and have a buoyant density of approximately 1.4 g/ml in cesium chloride gradients. These particles contain a 5.3-kb double-stranded RNA, while single-stranded RNA that corresponds to the viral positive strand is associated with less-dense particles. These results suggest a conservative and sequential mode of LRV1 viral RNA replication that is exemplified by the ScV L-A virus of yeast.

Animals↗
PubMed1992

Massive pleural effusion: an unusual presentation of Castleman's disease.

Giant lymph node hyperplasia (Castleman's Disease) is a rare cause of pleural effusion. We report the case of a 51 yr old West Indian male, who presented with a recurrent massive pleural effusion, due to a tumour arising from the pleura. He underwent parietal pleurectomy and subtotal excision of the tumour. Histological analysis of the specimen showed the features of multicentric Castleman's disease. Nine months following surgery he remains well, with no recurrence of the effusion.

Castleman Disease↗
PubMed1985

Analgesics for pain relief after gynaecological surgery. A two-phase study.

A two-phase, double-blind study was performed to assess the efficacy of various drugs in the relief of postoperative pain. Oral analgesia with two compounds (paracetamol 320 mg, caffeine 32 mg, codeine phosphate 8 mg and meprobamate 150 mg (Stopayne; Rio Ethicals) and dipyrone 500 mg, pitofenone hydrochloride 5 mg and fenpiverinium bromide 0,1 mg (Baralgan HS; Albert)) was found to produce satisfactory pain relief, and it is suggested that these oral compounds may be used from 12 hours postoperatively in uncomplicated cases. Parenteral administration of either pethidine 100 mg or dipyrone 2500 mg was found to be an ineffective form of pain relief, and it is suggested that the use of these drugs should be reviewed. In both phases of the study side-effects were infrequent and mild, and smoking did not have an influence on the results.

Acetaminophen↗
PubMed1983

Effects of trimazosin and prazosin on blood pressure and on pressor responses to phenylephrine in rats.

As part of an ongoing investigation into the cardiovascular properties of trimazosin, 99 male Sprague-Dawley rats were anesthetized and cannulas were placed in jugular veins for administration of drugs. The rats were injected with phenylephrine and then treated with either solvent, diazoxide, prazosin, or trimazosin. Blood pressure and heart rate were measured by a pressure transducer and a biotachometer, respectively; both were recorded continuously. Preliminary results indicate that trimazosin was less potent but more efficacious in lowering blood pressure than was prazosin and caused less blockade of the alpha-1-adrenoceptors even when its hypotensive effect exceeded that of prazosin. The differences in hypotensive potency and in alpha-1-receptor blockade are consistent with the fact that trimazosin has less affinity than does prazosin for alpha-1-receptors in vitro. The greater efficacy of trimazosin, compared to prazosin, is further evidence that in addition to alpha-1-receptor blockade, another mechanism contributes to the hypotensive effect of trimazosin. This mechanism has yet to be elucidated.

Animals↗