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D J Griffiths

Publications and source records attributed to D J Griffiths.

At least 19 recordsLinked to original sources
PubMed1998

S-phase-specific activation of Cds1 kinase defines a subpathway of the checkpoint response in Schizosaccharomyces pombe.

Checkpoints that respond to DNA structure changes were originally defined by the inability of yeast mutants to prevent mitosis following DNA damage or S-phase arrest. Genetic analysis has subsequently identified subpathways of the DNA structure checkpoints, including the reversible arrest of DNA synthesis. Here, we show that the Cds1 kinase is required to slow S phase in the presence of DNA-damaging agents. Cds1 is phosphorylated and activated by S-phase arrest and activated by DNA damage during S phase, but not during G1 or G2. Activation of Cds1 during S phase is dependent on all six checkpoint Rad proteins, and Cds1 interacts both genetically and physically with Rad26. Unlike its Saccharomyces cerevisiae counterpart Rad53, Cds1 is not required for the mitotic arrest checkpoints and, thus, defines an S-phase specific subpathway of the checkpoint response. We propose a model for the DNA structure checkpoints that offers a new perspective on the function of the DNA structure checkpoint proteins. This model suggests that an intrinsic mechanism linking S phase and mitosis may function independently of the known checkpoint proteins.

Cell Cycle Proteins↗
PubMed1998

A new external urethral occlusive device for female urinary incontinence.

OBJECTIVE: Determine the efficacy of a new external anti-incontinence urethral device. METHODS: A before-after 1 month trial, open longitudinal study of 155 women complaining of urinary incontinence recruited from a referral urogynecology practice and local media advertising was performed. Primary outcomes included assessing the efficacy of the device using visual analogue scales, quality-of-life questionnaires, 1- and 48-hour standardized pad tests, and voiding diary. Secondary outcomes consisted of the evaluation of the adverse effects and the clinical profile of patients willing to use the device after study completion. RESULTS: Ninety-six (62%) of 155 women enrolled completed the study. Scores on the visual analogue scales improved for the symptoms of stress incontinence, urgency, and urge incontinence (P < .001). The score for irritation/discomfort increased (P < .001). Data from diaries showed that 38 (44%, n = 86) patients were dry. Of 454 recorded patient-days, 325 (72%) were dry days. On pad testing, incontinence was cured in 49% (1-hour pad test, n = 59, P < .001) and 44% (48-hour pad test, n = 32, P < .001) of patients. Quality-of-life scores were significantly improved in 48% (n = 96, Incontinence Impact Questionnaire, P < .001) and 32% (n = 96, Urogenital Distress Inventory, P < .001) of patients. There was no increase in bacteriuria. After study completion, 61 (39%) women chose to continue using the device, but this was not predictable from baseline data. CONCLUSION: Use of this device resulted in a significant reduction in incontinence and improvement in quality-of-life issues with minimal adverse events in the majority of women. This new anti-incontinence device could become a useful addition to the armamentarium of nonsurgical options.

Adult↗
PubMed1997

Human retrovirus-5 proviral DNA is rarely detected in salivary gland biopsy tissues from patients with Sjögren's syndrome.

OBJECTIVE: To examine whether human retrovirus-5 (HRV-5) infection is associated with Sjögren's syndrome. METHODS: Salivary gland DNA was tested by nested polymerase chain reaction (PCR) for HRV-5 proviral DNA. Rigorous precautions were taken to prevent false-positive results from PCR contamination. Positive samples were confirmed by testing with an additional independent set of primers and were then sequenced. RESULTS: Ninety-two samples were examined (55 from Sjögren's syndrome patients, 37 from non-Sjögren's syndrome patients), 2 of which were positive. One was from a patient who had sicca symptoms but who did not satisfy the criteria for a diagnosis of Sjögren's syndrome. The other was from a patient with secondary Sjögren's syndrome. Owing to the extremely low virus load in minor salivary glands, the number of HRV-5-infected patients may be underestimated. In total, 3 different sequences of HRV-5 were identified which were 98% identical to the original sequence but which displayed variations between and within individuals. CONCLUSION: This is the first study to systematically seek a disease association with HRV-5, although with this method, an association with Sjögren's syndrome was not identified.

Amino Acids↗
PubMed1997

Bacteriuria in pregnancy: a comparison of Bangladeshi and Caucasian women.

During a 5-year period all urine culture results from pregnant Caucasian and Bangladeshi women booked for confinement at the Royal London Hospital, London, UK, were reviewed to determine race-specific rates of bacteriuria. The results showed that the overall prevalence of bacteriuria in the Caucasian group was 6.3% compared to 2.0% for the Bangladeshi women. Caucasian women were found to be at significantly greater risk across all pregnancy outcome and history categories, with the greatest risk observed in grand multiparous women (RR: 4.7, 95% CI: 2.8-8.3). Pregnancies that resulted in preterm delivery showed a strong association of bacteriuria in Caucasian women which was not seen in the Bangladeshi women (RR: 4.4, 95% CI: 2.0-8.7). The data suggest that Caucasian women have a significantly higher prevalence of bacteriuria in pregnancy than their Bangladeshi neighbors. Differences in hygiene practices and clothing may explain the observed differences in the bacteriuria rates.

Adult↗
PubMed1997

A novel exogenous retrovirus sequence identified in humans.

A 932-bp retrovirus sequence was cloned by reverse transcriptase PCR from salivary gland tissue of a patient with Sjögren's syndrome. The sequence is related to that of type B and type D retroviruses and was present in a sucrose density gradient fraction corresponding to that of an enveloped retrovirus particle. Sequences amplified from tissues of eight individuals with or without Sjögren's syndrome had over 90% similarity and were present at a level of less than one copy per 10(3) cells. The sequence was not detectable in human genomic DNA by PCR or by Southern hybridization. These data indicate that the sequence represents an infectiously acquired genome, provisionally called human retrovirus 5.

Amino Acid Sequence↗
PubMed1997

A novel mutant allele of Schizosaccharomyces pombe rad26 defective in monitoring S-phase progression to prevent premature mitosis.

A semipermissive growth condition was defined for a Schizosaccharomyces pombe strain carrying a thermosensitive allele of DNA polymerase delta (pol delta ts03). Under this condition, DNA polymerase delta is semidisabled and causes a delay in S-phase progression. Using a genetic strategy, we have isolated a panel of mutants that enter premature mitosis when DNA replication is incomplete but which are not defective for arrest in G2/M following DNA damage. We characterized the aya14 mutant, which enters premature mitosis when S phase is arrested by genetic or chemical means. However, this mutant is sensitive to neither UV nor gamma irradiation. Two genomic clones, rad26+ and cds1+, were found to suppress the hydroxyurea sensitivity of the aya14 mutant. Genetic analysis indicates that aya14 is a novel allele of the cell cycle checkpoint gene rad26+, which we have named rad26.a14. cds1+ is a suppressor which suppresses the S-phase feedback control defect of rad26.a14 when S phase is inhibited by either hydroxyurea or cdc22, but it does not suppress the defect when S phase is arrested by a mutant DNA polymerase. Analyses of rad26.a14 in a variety of cdc mutant backgrounds indicate that strains containing rad26.a14 bypass S-phase arrest but not G1 or late S/G2 arrest. A model of how Rad26 monitors S-phase progression to maintain the dependency of cell cycle events and coordinates with other rad/hus checkpoint gene products in responding to radiation damage is proposed.

Alleles↗
PubMed1997

Transmitter release differs at snake twitch and tonic endplates during potassium-induced nerve terminal depolarization.

Twitch and tonic muscle fibers of snake skeletal muscle differ in their synpatic as well as mechanical properties. These experiments were aimed at detemining the basis of the difference in vesicular release properties of nerve terminals at twitch and tonic endplates. Miniature endplate currents (MEPCs) were recorded from voltage-clamped garter snake muscle fibers depolarized by high K+ in either a control Ca2+ or high-Ca2+ solution. MEPC frequency increased at twitch and tonic endplates and remained elevated for 8 h during depolarization in control Ca2+. At twitch endplates depolarized in the presence of high Ca2+, an increase in MEPC frequency was followed by a progressive decline. In contrast, MEPC frequency remained elevated in high Ca2+ at tonic endplates. The observed decrease in MEPC frequency at depolarized twitch endplates in high Ca2+ was not a function of the level of depolarization or initial MEPC frequency, nor was it due to a reduction in MEPC amplitude and loss of MEPCs in baseline noise. An optical assay of presynaptic function in which the activity-dependent dye FM1-43 was used confirmed that quantal releases differs at twitch and tonic endplates. Most twitch nerve terminals were labeled by FM1-43 during prolonged depolarization with control Ca2+ or after brief depolarization with high Ca2+. In contrast, the number of twitch nerve terminals and the degree to which they were stained was greatly reduced after prolonged exposure to high K+ and high Ca2+, whereas depolarized tonic endplates were well stained by FM1-43 during brief and prolonged exposure to high Ca2+. FM1-43 staining also revealed variable levels of quantal release between individual boutons at twitch endplates after prolonged depolarization in high-Ca2+ solution. The observed reduction in presynaptic function at twitch nerve terminals after prolonged depolarization in high-Ca2+ solution was reversible and therefore not due to irreversible damage to terminal boutons. MEPC frequency increased at both twitch and tonic endplates when either Sr2+ or Ba2+ was substituted for high Ca2+ during K(+)-induced depolarization. Over time, in Sr2+ or Ba2+ solutions, MEPC frequency remained elevated at tonic endplates but declined at twitch endplates with a time course similar to that observed in high Ca2+. MEPC amplitudes at both endplates remained constant. We conclude that the regulation of quantal release differs in nerve terminals innervating twitch and tonic endplates and postulate that differential intraterminal accumulation of Ca2+ may underlie the observed difference in presynaptic function.

Animals↗
PubMed1996

Urge incontinence in elderly people: factors predicting the severity of urine loss before and after pharmacological treatment.

Geriatric patients with urge incontinence lose different amounts of urine and respond differently to treatment. Identification of factors predicting the amount of urine loss before or after treatment might help to select therapy. We have sought such factors in 41 elderly patients (23 women and 18 men), mean age 79 years with established urge incontinence that was urodynamically proven to be associated with detrusor hyperreflexia, who were treated with oxybutynin chloride. Urine loss was measured by 24-hour monitoring (mean 378 g/24 hour). Demographic, psychosocial, behavioral, cortical, circulatory, urodynamic, and urological factors were studied before and after treatment. Multiple regression analysis showed that, before intervention, factors predicting the amount of urine loss were fluid intake, voiding frequency, and impaired orientation on cognitive testing. After intervention, urine loss was significantly smaller (mean 259 g/24 hour). Different factors predicted the amount of this persistent incontinence: underperfusion of the cerebral cortex, reduced bladder sensation, and (again) impaired orientation. The analysis confirms that the severity of geriatric urge incontinence associated with detrusor hyperreflexia, particularly incontinence that is resistant to anticholinergic therapy, depends on cortical factors, that bladder sensation plays an important role, and that therapeutic manipulation of fluid intake and voiding frequency may offer a modest reduction in urine loss (e.g., about 40 g/day).

Aged↗
PubMed1996

Variability of post-void residual urine volume in the elderly.

Residual urine volume, though clinically important as a diagnostic tool, is reported to be variable and unreliable. Variability was examined among 14 geriatric patients, mean age 77 years. Residual urine was measured by ultrasound at three different times of day on each of two visits separated by 2-4 weeks. Results were examined by analysis of variance. Mean residual urine was 154 ml. Between-patient variability was large [standard deviation (SD) 246 ml]. There was no significant difference between values in men and women, nor between visits. Within-patient variability was large because of a large systematic variation with time of day (SD 128 ml), with greatest volumes in the early morning. The inherent, random variability of the measurement was much smaller than this (SD 44 ml). If the physiological factors causing the temporal variation could be controlled, more reproducible measurements would be possible.

Aged↗
PubMed1996

Pressure-flow studies of micturition.

The purpose of pressure-flow studies is to identify and quantify the abnormalities of bladder function (bladder outlet obstruction) that underlie disorders of voiding already demonstrated in simpler ways. Techniques of measurement and data quality control are of primary importance. Different methods for analyzing bladder outlet obstruction in the male like the Abrams-Griffiths nomogram and the linPURR have different aims but give broadly consistent results. Methods for assessing detrusor contractility and obstruction in the female patient are briefly discussed.

Female↗
PubMed1996

Urethral function.

Our understanding of the pathophysiological mechanisms of the urethra is still limited but improving. The valsalva leak point pressure measurement has been proposed as a simple and reproducible technique for the evaluation of urethral resistance, and progress has been made in the elucidation of urethral closure pressure generation that may lead to effective pharmacological therapy for treatment of functional obstruction. Magnetic resonance imaging is the newest technique for providing detailed anatomical information on the urethra and peri-urethral tissues.

Animals↗
PubMed1995

Fission yeast rad17: a homologue of budding yeast RAD24 that shares regions of sequence similarity with DNA polymerase accessory proteins.

Following DNA damage or a block to DNA synthesis, checkpoint pathways act to arrest mitosis and prevent the attempted segregation of damaged or unreplicated DNA. The rad17 locus of Schizosaccharomyces pombe is one of seven known radiation-sensitive (rad) loci which are absolutely required to prevent mitosis following DNA damage in fission yeast. Six of these (rad1, rad3, rad9, rad17, rad26 and hus1) are also required for the checkpoint which prevents mitosis from occurring before DNA replication is complete. We report here that the predicted rad17 gene product is a basic hydrophilic protein of 606 amino acids which contains five domains with sequence homology to replication factor C (RF-C)/activator 1 subunits. Western analysis and fusion with Green Fluorescent Protein indicate that the abundance and electrophoretic mobility of Rad17 is not significantly modified following a block to DNA synthesis or following DNA damage, and that Rad17 is localized in the nucleus. Rad17 function is not essential for growth, but is required for the function of the DNA structure-dependent checkpoints. Site-directed mutagenesis has been used to demonstrate the biological significance of the RF-C/activator 1-related domains. These studies have also defined an element of the radiation sensitivity caused by loss of Rad17 function which is not associated with the radiation-induced G2 arrest defect seen in the rad17.d null mutant cells.

Base Sequence↗
PubMed1995

The 14-3-3 proteins encoded by the BMH1 and BMH2 genes are essential in the yeast Saccharomyces cerevisiae and can be replaced by a plant homologue.

The 14-3-3 proteins comprise a family of highly conserved acidic proteins. Several activities have been ascribed to these proteins, including activation of tyrosine and tryptophan hydroxylases in the presence of calcium/calmodulin-dependent protein kinase II, regulation of protein kinase C, phospholipase A2 activity, stimulation of exocytosis and activation of bacterial exoenzyme S (ExoS) during ADP-ribosylation of host proteins. In addition, a plant 14-3-3 protein is present in a G-box DNA/protein-binding complex. Previously, we isolated the BMH1 gene from Saccharomyces cerevisiae encoding a putative 14-3-3 protein. Using the polymerase chain reaction method, we have isolated a second yeast gene encoding a 14-3-3 protein (BMH2). While disruption of either BMH1 or BMH2 alone had little effect, it was impossible to obtain viable cells with both genes disrupted. The cDNA encoding a plant 14-3-3 protein under the control of the inducible GAL1 promoter complemented the double disruption. Transfer of the complemented double disruptant to a medium with glucose resulted in the appearance of a high percentage of large budded cells. After prolonged incubation, these cells became enlarged with irregular buds and chains of cells defective in cell-cell separation became visible. These results suggest an essential role of the 14-3-3 proteins, possibly at a later stage of the yeast cell cycle.

14-3-3 Proteins↗
PubMed1995

Periurethral implantation of glutaraldehyde cross-linked collagen (Contigen) in women with type I or III stress incontinence: quantitative outcome measures.

OBJECTIVE: To evaluate the effectiveness of periurethral collagen (Contigen) implantation as a treatment for stress incontinence, using quantitative measures of urine loss and the patients' subjective response. PATIENTS AND METHODS: Twelve women, age range 46-87 years, had video urodynamic testing--confirming Type I or III stress urinary incontinence and were eligible for periurethral collagen implant. Eleven had had at least one anti-incontinence operation. One woman was withdrawn from the study because of a severe subcutaneous skin reaction 21 days after the skin-test and one patient declined follow-up. Ten patients had up to two implants each, introduced 3-5 months apart under local anaesthetic (5 mL collagen per implant). All patients underwent 10 h pad tests (with 2-hourly pad changes) at baseline and 8 weeks after collagen implant. The following quantitative measures of incontinence severity and voiding function were studied: urine loss during the 10 h test, number of wet pads, weight of urine in the wettest pad, maximum voided volume, residual volume on ultrasound, maximum flow rate and urinary flow curve pattern. Blind to the quantitative results, patients were asked to categorize their outcome as cured, improved and failed. RESULTS: There was a significant decrease in urine loss (P = 0.007), number of wet pads (P = 0.05) and weight of the wettest pad (g) (P = 0.03) from baseline to 8 weeks after the second collagen implant. There was no significant difference at any point in maximum voided volume, maximum urinary flow rate and residual volume after voiding measured on ultrasound. Objectively, two women appeared cured (< 5 g urine loss on 10 h pad test); subjectively, both reported themselves as improved (not cured); one subject stated she was cured and on pad test had 11 g urine loss; two women stated there was no change yet urine loss decreased markedly by > 60% from 434 g to 123 g and 533 g to 199 g. The remaining six stated they were improved although, objectively, their urine loss after the collagen implant remained high (mean 132 g, range 87-185). CONCLUSION: These results show a significant reduction in urine loss at 8 weeks after the second collagen implant and an objective cure rate of 18%. There was little relationship between the objective measure of success and the self-report. Of interest is the fact that no obstructive changes occurred in the voided amount, the flow curve and the residual volume after voiding.

Aged↗
PubMed1995

The rad18 gene of Schizosaccharomyces pombe defines a new subgroup of the SMC superfamily involved in DNA repair.

The rad18 mutant of Schizosaccharomyces pombe is very sensitive to killing by both UV and gamma radiation. We have cloned and sequenced the rad18 gene and isolated and sequenced its homolog from Saccharomyces cerevisiae, designated RHC18. The predicted Rad18 protein has all the structural properties characteristic of the SMC family of proteins, suggesting a motor function--the first implicated in DNA repair. Gene deletion shows that both rad18 and RHC18 are essential for proliferation. Genetic and biochemical analyses suggest that the product of the rad18 gene acts in a DNA repair pathway for removal of UV-induced DNA damage that is distinct from classical nucleotide excision repair. This second repair pathway involves the products of the rhp51 gene (the homolog of the RAD51 gene of S. cerevisiae) and the rad2 gene.

Amino Acid Sequence↗
PubMed1994

14-3-3 protein homologs required for the DNA damage checkpoint in fission yeast.

During the cell cycle, DNA is replicated and segregated equally into two daughter cells. The DNA damage checkpoint ensures that DNA damage is repaired before mitosis is attempted. Genetic studies of the fission yeast Schizosaccharomyces pombe have identified two genes, rad24 and rad25, that are required for this checkpoint. These genes encode 14-3-3 protein homologs that together provide a function that is essential for cell proliferation. In addition, S. pombe rad24 null mutants, and to a lesser extent rad25 null mutants, enter mitosis prematurely, which indicates that 14-3-3 proteins have a role in determining the timing of mitosis.

14-3-3 Proteins↗
PubMed1994

Identification and characterization of new elements involved in checkpoint and feedback controls in fission yeast.

To investigate the mechanisms that ensure the dependency relationships between cell cycle events and to investigate the checkpoints that prevent progression through the cell cycle after DNA damage, we have isolated mutants defective in the checkpoint and feedback control pathways. We report the isolation and characterization of 11 new loci that define distinct classes of mutants defective in one or more of the checkpoint and feedback control pathways. Two mutants, rad26.T12 and rad27.T15, were selected for molecular analysis. The null allele of the rad26 gene (rad26.d) shares the phenotype reported for the "checkpoint rad" mutants rad1, rad3, rad9, rad17, and hus1, which are defective in the radiation checkpoint and in the feedback controls that ensure the order of cell cycle events. The null allele of the rad27 gene (rad27.d) defines a new class of Schizosaccharomyces pombe mutant. The rad27 complementing gene codes for a putative protein kinase that is required for cell cycle arrest after DNA damage but not for the feedback control that links mitosis to the completion of prior DNA synthesis (the same gene has recently been described by Walworth et al. (1993) as chk1). These properties are similar to those of the rad9 gene of Saccharomyces cerevisiae. A comparative analysis of the radiation responses in rad26.d, rad26.T12, and rad27.d cells has revealed the existence of two separable responses to DNA damage controlled by the "checkpoint rad" genes. The first, G2 arrest, is defective in rad27.d and rad26.d but is unaffected in rad26.T12 cells. The second response is not associated with G2 arrest after DNA damage and is defective in rad26.d and rad26.T12 but not rad27.d cells. A study of the radiation sensitivity of these mutants through the cell cycle suggests that this second response is associated with S phase and that the checkpoint rad mutants, in addition to an inability to arrest mitosis after radiation, are defective in an S phase radiation checkpoint.

Amino Acid Sequence↗