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Biomedical subjects

G Watson

Publications and source records attributed to G Watson.

At least 73 records · Page 4Linked to original sources
PubMed1989

Use of the mouse for the isolation and investigation of stomach-associated, spiral-helical shaped bacteria from man and other animals.

Spiral-helical shaped bacteria other than Campylobacter pylori have been shown to infect the human stomach. The characteristic helical morphology of these bacteria appears to be similar to that of bacteria found in the stomachs of many other animal species. Early reports on gastric bacteria suggested that rodents may be useful for investigation and isolation of stomach-associated bacteria. Therefore, anaesthetised mice were given, through a stomach tube, a heavy suspension of a spiral-helical bacterium from a cat, scrapings of gastric mucus from primates, or a homogenised whole-antral biopsy from a human patient. At intervals after inoculation, gastric biopsies were examined by lightmicroscopy and electronmicroscopy for the presence of spiral-helical bacteria. Significant colonisation was observed in 40% of mice 1 week, and in 80% of mice 11 weeks, after inoculation with suspensions of the cat isolate. Mice were also successfully colonised by spiral bacteria present in homogenised human biopsy material and by other spiral bacteria from a monkey. These observations suggest that mice may prove to be useful animals for the study of gastric bacteria that are, as yet, non-cultivable and for analysis of some of the attributes commonly thought to be involved in colonisation.

Animals↗
PubMed1989

Androgen-regulated gene expression.

While a great deal of knowledge on the mechanisms of steroid hormone regulated gene expression now exists, specific information relating to androgens is lacking. A number of experimental systems have been developed and show promise as models for molecular studies of androgen regulation. Further development of these models must address the issue of whether or not the androgen receptor behaves similarly to other steroid receptors. This will require progress in the purification of the receptor itself or the cloning of its gene. Several features of androgen-regulated gene expression in the mouse kidney are applicable to a number of important biological problems. First, the presence of a variety of inducible mRNAs, whose responses to androgen are controlled at several genetic and molecular levels, should be valuable in obtaining basic information on mechanisms of gene regulation by hormones. Second, a genetic approach, for which the mouse is a convenient organism, will enable identification of novel regulatory elements that are responsible for variations in the hormonal activation of genes and that drive the evolution of species-specific gene expression phenotypes. Finally, the trophic effects of androgens in the mouse kidney afford opportunities to study a gene expression phenotype that is involved in cell growth; it will be of interest to determine how androgen induction of gene expression in kidney proximal tubule cells relates to the hormone-mediated growth of these cells.

Alcohol Dehydrogenase↗
PubMed1988

Mechanism of induction of mouse kidney alcohol dehydrogenase by androgen. Androgen-induced stimulation of transcription of the Adh-1 gene.

The three alcohol dehydrogenase genes in the mouse are subject to developmental, hormonal, and genetic control as revealed by variation in expression among inbred strains. The primary purpose of this study was to determine the mechanism by which androgen regulates the expression of the Adh-1 gene in kidney. In addition, the fold-induction in several inbred strains was examined in a search for possible genetic variation in the induction process, and Adh-1 expression in several tissues was studied. Testosterone treatment of female mice results in a 10-12-fold increase in alcohol dehydrogenase activity and a corresponding increase in the rate of enzyme synthesis accounts for this induction. The induction of Adh-1 mRNA after androgen treatment is sufficient to account for the induction in enzyme synthesis. An increase in Adh-1 transcription accounts for a substantial part of the increase in Adh-1 mRNA level following androgen simulation. This conclusion was reached using nuclear "run-on" assays, in vivo labeling, and a kinetic analysis of Adh-1 mRNA accumulation and loss in response to hormone. This induction requires androgen receptor. The fold induction by androgen of Adh-1 mRNA is similar in eight inbred mouse strains. There is almost a 100-fold variation in Adh-1 mRNA concentrations among various mouse tissues. Tissues with lowest level of expression are brain and heart, while liver and adrenals have the highest content of Adh-1 mRNA.

Alcohol Dehydrogenase↗
PubMed1988

Conjugation of monoclonal antibodies to a synthetic peptide substrate for protein kinase: a method for labelling antibodies with 32P.

In recent years, radiolabelled monoclonal antibodies have been evaluated for their use in the diagnosis and treatment of neoplastic disease. One isotope which has not been assessed for antibody targeting is 32P, even though it has many favourable radiobiological characteristics and has been used clinically for the treatment of certain neoplastic disorders such as polycythaemia rubra vera. The main drawback so far in using 32P has been the absence of a general method for phosphorylating antibodies. We have now developed a novel process for the phosphorylation of immunoglobulins which is rapid, efficient and allows high specific activities to be achieved (greater than 10 muCi micrograms-1). The technique involves the chemical conjugation of Kemptide, a synthetic heptapeptide substrate for kinases, to immunoglobulins. The antibody-Kemptide conjugate can then be phosphorylated using protein kinases and [32P]-gamma-ATP. The procedure does not compromise the binding activity of the antibody. The 32P-labelled monoclonal antibodies were stable in human, mouse and rat plasmas in vitro, although they cleared from the bloodstream of mice with a beta-phase half life of 2 days which is approximately two times faster than that of native antibody. The application of this phosphorylation technique should allow the therapeutic potential of targeted 32P to be assessed.

Animals↗
PubMed1988

An antigenic analysis of the adenovirus type 2 fibre polypeptide.

Twenty-seven monoclonal antisera were generated against the SDS-denatured fibre of adenovirus type 2. The antisera were characterized using radioimmune assay, fluorescent antibody tests, immune precipitation, Western blotting, haemagglutination and neutralization, and formed six groups as follows: A, type-specific neutralizing antisera which exhibited haemagglutination inhibition (Hi+); B, type-specific non-neutralizing antisera which did not exhibit haemagglutination inhibition (Hi-); C, subgroup-specific neutralizing antisera Hi+; D, a subgroup-specific neutralizing antiserum Hi-; E, subgroup-specific non-neutralizing antisera Hi-; F, a subgroup-specific neutralizing antiserum Hi- which did not react in Western blotting tests. The C-terminal 201 amino acids of the fibre were expressed in Escherichia coli and a total of six antisera from groups A, B and C recognized five epitopes carried on this region which in several models is thought to form the knob of the fibre. At least eight epitopes were expressed by the entire native fibre. The five epitopes of the C-terminal end of the fibre formed three antigenic sites. Two sites each consisted of a neutralizing type-specific and a neutralizing group-specific epitope which overlapped in position. The remaining site consisted of a type-specific, non-neutralizing epitope.

Adenoviridae↗
PubMed1988

Lasertripsy for ureteric stones in 120 cases: lessons learned.

The pulsed dye laser has proved to be an effective and safe method of treating ureteric stones; 120 patients have been treated. Ureteroscopic lasertripsy (107 cases) had an overall success rate of 84%. The failures were due to mobile stones inadvertently flushed back into the kidney (14%) and 2% of patients required open ureterolithotomy after failure of two ureteroscopic procedures. "Blind" lasertripsy (13 cases) was safe but not as efficient, the success rate being only 23%.

Female↗
PubMed1988

mRNA synthesis rates in vivo for androgen-inducible sequences in mouse kidney.

A method was developed for measuring in vivo rates of mRNA synthesis in mice by pulse-labeling with the RNA precursor [3H]orotate and then using hybridization to recover specific mRNAs. The efficiency of recovery is determined with synthetic RNAs as internal hybridization standards. The method is particularly applicable to the kidney since this organ shows a strong preferential uptake of the label. Rates of synthesis, expressed as a fraction of total RNA synthesis, were measured for the androgen-inducible mRNAs coding for beta-glucuronidase (GUS), ornithine decarboxylase (ODC), the protein coded by the RP-2 gene, and the so-called kidney androgen-regulated protein (KAP). Control mRNAs coded for beta-actin, phosphoenolpyruvate carboxykinase, and major urinary protein. Testosterone markedly increased the synthesis of the androgen-inducible mRNAs, but not the control mRNAs. Induction was not seen in mutant mice lacking functional androgen receptor protein. For GUS, ODC, and RP-2 mRNAs, the fold induction of synthesis was less than the fold induction of concentration, suggesting that mRNA stabilization also plays a part in the response to androgen. For GUS, ODC, and RP-2 mRNAs, but not KAP mRNA, induction of synthesis was rapidly reversed after testosterone removal. KAP mRNA was also exceptional in that its concentration was disproportionately high compared with its rate of synthesis, implying that it is a particularly stable mRNA.

Animals↗
PubMed1987

The pulsed dye laser for fragmenting urinary calculi.

The properties of a laser which effect stone fragmentation have been studied. The pulsed dye laser emitting at 504 nm. in one microsecond duration pulses appears to be the optimum out of a wide range of parameters tested. The laser is coupled to a 200 micron core fiber; this complete with its cladding has a total diameter of only 0.25 mm. Most calculi are fragmented by a series of pulses of up to 30 mJ. The system is used by firing bursts of pulses with the fiber actually in contact with the stone. The result is a very controlled fragmentation which is particularly suited to use in the confines of the ureter. This modality of treatment utilises less energy than ultrasound or electrohydraulic probes to fragment a stone and the very fine, flexible fiber represents a considerable miniaturization.

Calcium Oxalate↗
PubMed1987

An assessment of the pulsed dye laser for fragmenting calculi in the pig ureter.

The pulsed dye laser was used to fragment ureteric calculi in 10 pig ureters, compared to electrohydraulic disintegration in six pig ureters. The stones were impacted in the proximal ureter and approached by rigid ureteroscopy. Four ureters did not have stones impacted but had ureteroscopes passed. The stones were fragmented and the particles left to pass spontaneously. The degree of inflammatory reaction was graded at the site of fragmentation as well as in the middle and lower ureter. The degree of inflammation seen at the site of fragmentation was significantly less in the laser group than in the electrohydraulic group (p = 0.0027). It was noted that the degree of inflammation seen in the lower ureter was significantly greater than that seen at the site of fragmentation (p = 0.01), and that this grade of inflammation correlated well with the size of ureteroscope used (p = 0.0026). Further, the degree of dilatation of the ureter and pelvicalyceal system was significantly greater when the larger calibre ureteroscope had been used (p = 0.0056) ranging up to hydronephrosis with flattening of the papillae. If there is any parallel which can be drawn between the pig ureter and the human ureter then it suggests that ureteroscopy is more significant than the modality of fragmentation used. The contribution of the laser may therefore be more by the miniaturization of instrumentation which will be made possible than by any advantage it may have as a fragmenter.

Animals↗
PubMed1987

Pulsed dye laser fragmentation of ureteral calculi: initial clinical experience.

The pulsed dye laser, emitting at wavelengths of 504 nm. for 1 microsecond. at a frequency of 5 Hz. transmitted via a 250 mu in diameter silicon-coated quartz fiber, was passed into the ureter through the working channel of a 9.5F rigid ureteroscope. Seventeen patients with ureteral calculi too large to be extracted directly, who were unable to be treated by extracorporeal shock wave lithotripsy or who otherwise would have required transureteral or percutaneous ultrasonic stone removal, underwent attempted stone fragmentation by pulsed dye laser application. Of the 17 calculi 16 were fragmented to spontaneously passable or easily extractable fragments. There was no significant ureteral injury, thermal or otherwise, attributable to laser energy action. At 3-month followup 15 of the 17 ureters had improved and 2 showed evidence of ureterscopic injury. The mechanism of stone fragmentation by laser is small volume "shock wave" formation.

Coloring Agents↗
PubMed1987

Genetic variations in kinetic constants that describe beta-glucuronidase mRNA induction in androgen-treated mice.

The kinetics of beta-glucuronidase mRNA induction by androgen in mouse kidney were determined for A, B, and CS haplotypes of the beta-glucuronidase gene. After a lag period, the kinetics of mRNA (R) induction are approximated by the turnover equation dR/dt = k1 - k2R. The A haplotype differs from the B primarily in the duration of the lag period and in k1, the rate constant determining the initial slope of the induction curve. The CS haplotype differs from B primarily in k2, the first-order rate constant that determines the half-time for induction. None of the haplotypes differs significantly in the half-life of beta-glucuronidase mRNA as measured by deinduction. Thus, there was no correlation between the half-time or extent of induction and the half-life of the RNA. Comparing half-times for induction with the half-life of the mRNA suggests that message stabilization can at most account for only part of the induction. We conclude that transcriptional activation of the beta-glucuronidase gene must be an important component of induction. Estimating absolute numbers of mRNA molecules and absolute rates of gene transcription, it appears that before induction there is approximately one molecule of beta-glucuronidase mRNA per cell and that each gene copy is transcribed once every 35 to 40 h. Depending on the haplotype examined, after induction, mRNA goes up to 80 to 400 molecules per induced cell. In the A haplotype, which has the highest induction, this corresponds to one transcript from each gene every 6 min if there is no induced stabilization of beta-glucuronidase mRNA, and one every 30 min if there is. Thus, it seems unlikely that more than one transcript is ever being synthesized at the same time from the beta-glucuronidase gene.

Animals↗
PubMed1987

An unusual case of neonatal myasthenia.

An unusual case of neonatal myasthenia gravis is reported in an infant who had respiratory failure due to diaphragmatic weakness. Although power and tone in the limbs were normal, fatiguability of both diaphragm and peripheral muscles was demonstrated. Acetylcholine receptor antibodies were absent in the mother, which suggests that an alternative humoral mechanism may have been responsible for the transient (6-week) neonatal weakness.

Female↗
PubMed1986

Androgen induction of messenger RNA concentrations in mouse kidney is posttranscriptional.

The concentrations of several mRNAs in mouse kidney increase in response to testosterone. To determine if the increases are generated at the level of gene transcription, we have assayed transcription rates for several androgen-inducible mRNAs in kidney nuclei in vitro. No significant changes were found in the synthesis of three mRNAs whose concentrations increase 10-20-fold during testosterone treatment. Kinetic analysis of changes in transcript levels after testosterone administration and withdrawal suggests that mRNA stabilization is a major factor in the inductions. Thus, the androgen-mediated induction of these kidney mRNAs is generated predominantly at the posttranscriptional level.

Animals↗
PubMed1986

Diagnosis and treatment of posterior urethral injury.

The initial investigation and diagnosis in 28 patients with posterior urethral trauma are presented. Twenty-five patients underwent either primary realignment for complete rupture or cystostomy alone for partial rupture. The results of their management are reported.

Adolescent↗
PubMed1985

Genetic variation for enzyme structure and systemic regulation in two new haplotypes of the beta-glucuronidase gene of Mus musculus castaneus.

Two new haplotypes of the [Gus] gene complex have been characterized following their transfer from Mus musculus castaneus, where they were found, to a C57BL/6J genetic background. The [GUS]CS haplotype carries a new structural allele, Gus-scs, coding for enzyme with decreased thermolability and lacking an antigenic site present in other beta-glucuronidase allozymes. The [Gus]CL haplotype carries another new structural allele, Gus-scl, that codes for enzyme with increased thermolability and possessing the antigenic site. Both CS and CL beta-glucuronidase have the same catalytic activity/molecule as the standard B allozyme from C57BL/6J mice. Mice carrying either the [Gus]CS or [Gus]CL haplotype have reduced enzyme activity in all tissues examined at all stages of development. The reduced enzyme activity is partially accounted for by reduced rates of enzyme synthesis, and the remainder probably results from increased rates of enzyme turnover. beta-Glucuronidase mRNA levels in these mice were not reduced suggesting that the observed reduction in enzyme synthesis is due to a decreased efficiency of translation for CS and CL mRNA.

Alleles↗
PubMed1985

Weak androgen reduces the rate constant of beta-glucuronidase induction.

Administration of androgen to mice induces kidney beta-glucuronidase. Measuring beta-glucuronidase activity, rate of beta-glucuronidase synthesis, beta-glucuronidase mRNA activity and beta-glucuronidase mRNA concentration, the time course of induction was compared using a strong androgen, dihydrotestosterone (DHT), and a weakly androgenic progestin, medroxyprogesterone acetate (MPA). Using MPA resulted in a longer lag, a 3-4-fold slower rate of induction as defined by the forward rate constant, ka, a lower final extent of induction, and a slightly lower turnover constant, kb. Differences in kinetics of induction were consistent for all 4 measured parameters, and mimicked previously described genetic differences in these rate constants. The coordinate induction of beta-glucuronidase protein and beta-glucuronidase mRNA indicates that the response to androgen is regulated at a pre-translational level. That substitution of MPA for DHT decreases ka, rather than increasing kb, suggests that induction of beta-glucuronidase follows an increased rate of mRNA synthesis rather than a decreased rate of mRNA turnover. Finally, the results are consistent with a model in which the kinetic constants for beta-glucuronidase induction are dependent on the concentration of receptor molecules in the active conformational state.

Animals↗
PubMed1985

Properties of rat and mouse beta-glucuronidase mRNA and cDNA, including evidence for sequence polymorphism and genetic regulation of mRNA levels.

cDNA clones containing partial sequences for beta-glucuronidase (beta G) were constructed from rat preputial gland RNA and identified by their ability to selectively hybridize beta G mRNA. One such rat clone was used to isolate several cross-hybridizing clones from a mouse-cDNA library prepared from kidney RNA from androgen-treated animals. Together, the set of mouse clones spans about 2.0 kb of the 2.6-kb beta G mRNA. Using these cDNA clones as probes, a genomic polymorphism for DNA restriction fragment size was found that proved to be genetically linked to the beta G gene complex. A fragment of beta G cDNA was subcloned into a vector carrying an SP6 polymerase promoter to provide a template for the in vitro synthesis of single-stranded RNA complementary to beta G mRNA. This provided an extremely sensitive probe for the assay of beta G mRNA sequences. Using either nick-translated cDNA or transcribed RNA as a hybridization probe, we found that mouse beta G RNA levels are strongly induced by testosterone, and that induction by testosterone is pituitary-dependent. During the lag period preceding induction, during the induction period itself, and during deinduction following removal of testosterone, beta G mRNA levels paralleled rates of beta G synthesis previously measured by in vivo pulse-labelling experiments. Genetic variation in the extent of induction affected either the level of beta G mRNA or its efficiency of translation depending on the strain of mice tested.

Amino Acid Sequence↗