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M W Watson

Publications and source records attributed to M W Watson.

16 recordsLinked to original sources
PubMed1995

The CrP operon of Chlamydia psittaci and Chlamydia pneumoniae.

One of the critical developmental events during the unique intracellular life cycle of Chlamydiae is their differentiation from a metabolically active, replicative form or reticulate body (RB) to an infectious extracellular form of the organism (elementary body or EB). This process is characterized by the expression of two extraordinarily cysteine-rich envelope proteins of molecular masses 9 kDa and 60 kDa. We describe the molecular cloning and sequence determination of the 9 kDa cysteine-rich proteins (CrPs) of C. pneumoniae and C. psittaci. Comparison of these 9 kDa CrP amino acid sequences with those of C. trachomatis showed regions of structural variation and conservation. Transcription of the 9 kDa CrP genes occurred as both a monocistronic message and as a bicistronic message which included the 60 kDa CrP gene. Transcription of the 9 kDa and 60 kDa CrP genes was tightly linked to the chlamydial growth cycle with synthesis of their mRNAs and consequent translation of the 60 kDa CrPs occurring as RBs differentiated to form EBs. The maximal rate of transcription occurred late in the growth cycle from a single but highly conserved promoter which had close similarity with the Escherichia coli consensus promoter sequences. A stem and loop structure which could be involved in regulating translation of mRNA occurred in all three species between the transcriptional start point and the ribosome binding site. Although transcription is initiated from a single promoter in all three chlamydial species, transcriptional termination points for the monocistronic and bicistronic mRNAs differ in both number and position.

Amino Acid Sequence↗
PubMed1994

Immunoreactivity of the 60 kDa cysteine-rich proteins of Chlamydia trachomatis, Chlamydia psittaci and Chlamydia pneumoniae expressed in Escherichia coli.

The 60 kDa cysteine-rich proteins (CrPs) of Chlamydia are developmentally regulated outer envelope proteins synthesized late in the chlamydial growth cycle. These proteins, found only on the extracellular infectious elementary bodies, elicit major antibody responses in chlamydial infection. We have cloned and expressed in Escherichia coli the complete 60 kDa CrP genes from Chlamydia trachomatis, C. psittaci and C. pneumoniae. The recombinant products were expressed as either 'native' proteins or as fusions with the bacteriophage T7 gene 10 protein. Electron microscopy showed that recombinant proteins were produced as insoluble inclusions within the E. coli host cells. The recombinant 60 kDa CrPs were purified and used to raise high titre polyclonal antisera. In immunoblot analysis these antisera reacted with the 60 kDa CrPs from purified elementary bodies of all three chlamydial species in a genus-specific manner. Further molecular analysis allowed the genus-specific cross-reacting epitopes to be localized by using overlapping synthetic peptides covering the C. trachomatis 60 kDa CrP. Immunogold labelling experiments, using purified infectious elementary bodies from the three chlamydial species indicated that the 60 kDa CrPs are not surface accessible to antibody binding.

Amino Acid Sequence↗
PubMed1992

Use of anatomical dolls by Boston-area professionals.

Anatomical dolls are a widely used but controversial tool for interviewing child victims of sexual abuse. The present research examines how a representative sample of professionals who evaluate children actually use the dolls. Contrary to past reports, the results revealed that 96.6% of professionals who use the dolls had received training in anatomical doll use, 77.8% followed some standard protocol for interviewing, and 97.3% had at least 1 year of experience with anatomical dolls. The results also revealed that the majority of professionals did not engage in the "leading" behaviors of presenting unclothed dolls to children or undressing the dolls for the child, again contrary to past reports. The present research indicates that the professionals in this sample are more experienced and better trained than is typically thought.

Child↗
PubMed1991

Metabolism of 99mTc-L,L-ethyl cysteinate dimer in healthy volunteers.

99mTc-L,L-Ethyl cysteinate dimer (ECD) is a brain-perfusion imaging agent, which exhibits selective retention in brain and rapid renal excretion. The pharmacokinetics and metabolism of ECD were studied in vivo in healthy humans and its metabolism in vitro was evaluated in tissue from human brain. In vitro studies showed 99mTc-L,L-ECD to be metabolized to a polar 99mTc-complex. It has been shown previously that most of the activity of 99mTc retained in the brain of the monkey in vivo is in the form of a polar 99mTc complex (Walovitch, Hill, Garrity, Cheesman, Burgess, O'Leary, Watson, Ganey, Morgan and Williams, 1989). Whole body images of the distribution of 99mTc-L,L-ECD (10 mCi i.v.) in four adult males showed good uptake in brain, with slow elimination (6.8 +/- 0.3% injected dose [mean +/- SE] at 5 min), with less than 25% decrease in activity during 4 hr of imaging. Background areas in the head and lungs washed out rapidly, providing ideal imaging conditions. Elimination of 99mTc from venous blood was biphasic, with a plateau of activity between 2-15 min (7-8% injected dose) before a terminal phase, with a t1/2 of a few hours. Organic extraction of whole venous blood showed greater than 50% of the 99mTc-L,L-ECD to be in the form of polar metabolite(s) at 5 min. They were identified in the urine as the 99mTc ethylenediylbis-L-cysteine, monoethyl ester complex (ECM) and the 99mTc-ethylenediylbis-L-cysteine complex (EC). These metabolites were excreted rapidly (75% injected dose in urine within 6 hr). The results of this study support the hypothesis that the selective retention in brain, rapid blood elimination and renal excretion of 99mTc-L,L-ECD is due to its metabolic transformation to polar end products.

Adult↗
PubMed1991

Genetic diversity and identification of human infection by amplification of the chlamydial 60-kilodalton cysteine-rich outer membrane protein gene.

The 60-kDa cysteine-rich outer membrane protein genes of Chlamydia psittaci, Chlamydia pneumoniae, and Chlamydia trachomatis have very different 5' ends, but two areas flanking this variable region show absolute sequence conservation. This observation permitted differentiation of the three species of Chlamydia by the polymerase chain reaction (PCR), forming the basis of a diagnostic test for chlamydial infections. The PCR product containing the variable region of the respective 60-kDa CrP genes was also subjected to restriction endonuclease digestion, enabling differentiation of individual type strains of C. psittaci. Differentiation was possible between lymphogranuloma venereum and trachoma isolates of C. trachomatis. The PCR-based diagnostic test was successful with all strains of chlamydiae studied. The PCR primers showed high specificity and did not produce any product with common bacterial pathogens that may share the same sites of infection.

Bacterial Outer Membrane Proteins↗
PubMed1989

Chlamydia trachomatis 60 kDa cysteine rich outer membrane protein: sequence homology between trachoma and LGV biovars.

An 820 bp AccI-PstI fragment of the 60 kDa cysteine rich outer membrane protein (CrP) gene from C. trachomatis serovar L1 was used as a probe to locate the 60 kDa CrP gene of a recent serovar B trachoma isolate (Jali 20/OT). The probe hybridized to a single 1.8 kb SpeI fragment in Southern blot analyses of different restriction endonuclease digests of C. trachomatis serovar B DNA. This fragment was ligated into Lambda Zap II arms and Bluescript SK(-) recombinants, released by infection with the helper phage R408, were used as template for DNA sequence determination. Sequence analysis demonstrated a very high level of homology between the Jali 20/OT 60 kDa CrP and the previously published serovar L1 60 kDa CrP with only 8 out of 507 amino acid substitutions between the two proteins.

Amino Acid Sequence↗
PubMed1988

Treatment of tardive dyskinesia: preliminary report on use of tetrabenazine.

Tetrabenazine has been used for treatment of tardive dyskinesia sporadically over the past twenty years. Dose has usually been decided empirically without assaying blood levels. This report describes 23 cases treated successfully with tetrabenazine. Our method of measuring levels of tetrabenazine and its metabolites in biological samples is described briefly.

Adult↗
PubMed1986

Direct injection high-performance liquid chromatography of tetrabenazine and its metabolite in plasma of humans and rats.

A convenient, selective, and sensitive reversed-phase HPLC assay was developed to measure concentrations of the dopamine-depleting agent, tetrabenazine (1,3,4,6,7,11b-hexahydro-3-isobutyl-9,10-dimethoxy-2H-benzo(a)quinoli zin-2-one) and its dihydro metabolite in the plasma of patients with tardive dyskinesia receiving therapeutic doses of the drug and in the plasma of rats. The method involves plasma protein precipitation, oxidation of the compounds with mercuric acetate at 110 degrees C for 1 h, addition of internal standard, and injection into the instrument. Fluorescence detection was utilized at excitation and emission wavelengths of 265 and 418 nm, respectively. The peaks from the drug, its metabolite, and at least three other substances were best resolved at 60 degrees C using a mobile phase of water:acetonitrile:acetic acid:triethylamine (65:33:2:0.15) at a flow rate of 0.6 mL/min; the 4.6 mm X 10 cm column contained 5 micron of octadecylsilane packing. To assess the applicability of the assay, the drug was administered intravenously to rats, and plasma concentrations were determined before (by UV-HPLC) and after (by fluorescence-HPLC) the oxidative procedure. In addition, the MS spectra of tetrabenazine and the dihydro metabolite, isolated from biological samples, were identical to those of authentic samples. Excellent linearity was observed between the peak area ratios and concentrations over the ranges 0.5-200 and 2-1000 ng/mL of the drug and the metabolite, respectively. Minimum quantifiable concentrations of the drug and its metabolite were 0.5 and 2.0 ng/mL, respectively. The sensitivity was found to be adequate for pharmacokinetic studies of tetrabenazine in humans and rats.

Animals↗
PubMed1984

Agents and recipient objects in the development of early symbolic play.

The development of 2 components of early symbolic play--children's symbolic transformations of agents of action and recipient objects of action--was assessed in 48 children from 14 to 25 months of age. A 5-step sequence was predicted based on a combined weighting of agent substitutions and recipient object substitutions in each step. Children observed an adult model who pretended to talk into a telephone using each agent and object substitution in all combinations and then were allowed to demonstrate their own imitative pretending for each step. Based on the children's profiles of steps passed and failed, the sequence was found to form a Guttman scale and be age related. 2 types of possible underlying sequences were discussed.

Child Development↗
PubMedDate not supplied

Pharmacokinetics of tetrabenazine and its major metabolite in man and rat. Bioavailability and dose dependency studies.

The pharmacokinetics of tetrabenazine (TBZ), a catecholamine and serotonin depletor, and its major metabolite, dihydrotetrabenazine (HTBZ), were studied in four patients affected by tardive dyskinesia, who were under treatment with different doses of TBZ (12.5-37.5 mg, t.i.d.), and in the rat. In the patients, the steady-state area under the plasma concentration-time curves (AUCs) of the metabolite were 82.6-199-fold higher than those of TBZ. The drug showed a small and erratic bioavailability (F = 0.06 +/- 0.026, mean +/- SD). It appears to be extensively metabolized, as no unchanged TBZ could be detected in the urine of the patients. Single oral doses of 0.5-10 mg/kg and single iv dose of 1 mg/kg of TBZ were each administered to four to six rats. The clearance of the drug following iv administration to the rat (mean +/- SD, 58.9 +/- 6.01 ml X min-1 X kg-1) was very close to the rat hepatic blood flow indicating a perfusion-limited clearance. An F value of 0.17 was obtained following iv and po doses of 1 mg/kg TBZ in the rat. The oral absorption of TBZ seems to be rapid and almost complete. Plots of the AUCs of TBZ and HTBZ vs. five different po doses (0.5-10 mg/kg) were linear with correlation coefficients of 0.998 and 0.986 for TBZ and HTBZ, respectively, suggesting linear kinetics in the examined dosage range. In both the patients and rats, the plasma profile of TBZ followed characteristics of a multiexponential pharmacokinetic model.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗