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G J Griffiths

Publications and source records attributed to G J Griffiths.

At least 19 recordsLinked to original sources
PubMed2001

Cellular damage signals promote sequential changes at the N-terminus and BH-1 domain of the pro-apoptotic protein Bak.

The pro-apoptotic protein Bak is converted from a latent to an active form by damage-induced signals. This process involves an early exposure of an occluded N-terminal epitope of Bak in intact cells. Here we report a subsequent damage-induced change in Bak, detected using an antibody to the central BH-1 domain. Bak co-immunoprecipitated with Bc1-x(L) both in undamaged cells and early after damage, when the N-terminal epitope was exposed but the BH-1 epitope remained occluded. A subsequent decrease in binding of Bak to Bc1-x(L) correlated with exposure of an epitope in the Bak BH-1 domain. Overexpression of Bc1-x(L) did not affect the kinetics of exposure of the Bak N-terminal epitope but delayed exposure of the BH-1 domain. Cytochrome c release from mitochondria facilitates the activation of apoptotic caspases. The majority of cells with exposed Bak BH-1 domains contained cytosolic cytochrome c. However, a small proportion of cells exhibited exposed Bak BH-1 domains that co-localized with mitochondrial cytochrome c. The data are consistent with a two-step model for the activation of Bak by drug-induced damage signals where dissociation of Bc1-x(L) from the BH-1 domain of Bak occurs immediately prior to or concomitantly with cytochrome c release.

Amino Acid Chloromethyl Ketones↗
PubMed2001

Damage-induced Bax N-terminal change, translocation to mitochondria and formation of Bax dimers/complexes occur regardless of cell fate.

Sequential steps in the activation of the pro-apoptotic protein Bax are described for cells with different sensitivity to cytotoxins. SH-EP1 and SH-SY5Y human neuroblastoma cells, derived from a single precursor cell line, differed in their sensitivity to taxol but showed the same sensitivity to cisplatin. Both drugs, in both cell lines, induced exposure of a constitutively occluded N-terminal epitope of Bax. This was reversible and occurred before the translocation of cytosolic Bax to mitochondria. The N-terminal change in Bax, its subsequent movement to mitochondria and its dimerization/complex formation were insufficient for commitment to death, occurring in the same proportion of cells that either maintained (SH-SY5Y) or lost (SH-EP1) clonogenic survival after taxol treatment. Suppression of taxol-induced apoptosis occurred upstream of cytochrome c release from mitochondria in SH-SY5Y cells. The data suggest that a further drug damage-induced event occurs after Bax dimerization/complex formation but prior to cytochrome c release. This event was absent in the taxol-resistant cells.

Antineoplastic Agents↗
PubMed2000

Albumin as an outcome measure in haemodialysis in patients: the effect of variation in assay method.

BACKGROUND: Serum/plasma albumin is an important predictor of future mortality/morbidity in haemodialysis (HD) patients and has been proposed as an important audit measure. Different methods of albumin assay give different results and the bias between methods may be greater in renal failure patients. METHODS: Albumin concentration in plasma was measured by three methods, two dye-binding methods (bromocresol green (BCG) and bromocresol purple (BCP)) and an immuno-turbidimetric (ITM) method, in 143 HD patients (group I) and 49 non-renal patients (group II). Comparisons were made between means, variation in differences across a range of albumin concentrations and on the percentage of patients within the normal range. RESULTS: In HD patients (group I), BCG over-estimated plasma albumin compared with the other two methods. The difference could be as much as 10 g/l and was more marked in hypoalbuminaemic patients. The BCP method gave results closer to the ITM method, particularly in HD patients. These differences were less marked in group II patients but both methods overestimated albumin compared with the ITM method. Using the BCG local laboratory normal range, 84% of HD patients had plasma albumin concentrations within the normal range but this fell to 57% if the BCP results were used. CONCLUSIONS: The method for determining albumin concentration has a marked effect on the results particularly in HD patients. BCG, the most commonly used method, gives higher results than other methods and correlates poorly with an immunological method. These differences make comparative audit between nephrology units difficult and have implications for other biochemical variables and other specialties.

Biomarkers↗
PubMed2000

Exisulind Cell Pathways.

Cell Pathways has developed exisulind (Aptosyn), an oral apoptosis modulator and cGMP phosphodiesterase inhibitor, for the potential treatment of several oncologic indications including precancerous adenomatous polyposis coli (APC), also known as familial adenomatous polyposis (FAP), precancerous sporadic colonic polyps, cervical dysplasia and the prevention of tumor recurrence in prostate and breast cancer. An NDA filing for the treatment of precancerous APC, for which the US FDA designated exisulind a Fast Track product in July 1998, was initially expected in March 1999 [291313]. However, in January of the same year the company stated that it anticipated a delay in the NDA filing. The decision was based on unsatisfactory phase III data [308912], [313124]. In June 1999, the company completed analysis of the phase III trial data [328000] and the NDA was submitted in August 1999. An NDA was accepted for review by the FDA in October 1999 for the treatment of APC [328000], [338007], [344721], after data from three additional trials were submitted to the FDA in support of the NDA. At this time phase II/III trials were also ongoing for prostate and breast cancer recurrence [287250], [326795]. Approval for the indication of FAP had been expected by the end of 2000 [365737] but in September 2000 the FDA completed its initial review and advised Cell Pathways that exisulind will not be approved at this time. Cell Pathways has received a 'non-approvable' letter and intends to advise the FDA of its intent to amend the NDA and to request a meeting to address the deficiencies in the NDA [383249], [383560]. The first of the three additional trials submitted to the FDA in October 1999 was a 6-month, open-label trial involving 48 of the patients who completed a phase II/III study of exisulind in early 1999. After 6 months of treatment with exisulind, 25 patients who had previously been taking placebo experienced a 50% reduction in polyp formation. The patients continuing treatment with exisulind exhibited a further 50% reduction from their already reduced rate of polyp formation [344991]. The second study was an extension study of 11 patients who participated in a 6-month, open-label, phase I/II, dose-ranging, safety and efficacy trial. As of October 1999, these patients were still on therapy and had been receiving exisulind for between 36 and 50 months. They had all experienced statistically significant reductions in polyp formation rates [344991]. The third study was a double-blind, placebo-controlled safety study of 26 patients. All patients exhibited a trend of reduced new polyp formation when compared to placebo. Exisulind was generally well-tolerated by all patients during the course of the studies [344991]. In July 2000, Cell Pathways signed a marketing and distribution agreement for Canada with Paladin Labs, allowing Paladin exclusive rights to commercialize exisulind within Canada [376072]. Also in July 2000, Cell Pathways announced that patents covering methods of identifying compounds that selectively stimulate apoptosis have been allowed in Europe and Japan. The patents describe the mechanism of action of Cell Pathways' SAANDs, including exisulind, and use of that knowledge in screening for new drugs [374888]. In January 1999, the company received US-05858694 covering the mechanism of action of exisulind [311504].

Animals↗
PubMed1999

Cell damage-induced conformational changes of the pro-apoptotic protein Bak in vivo precede the onset of apoptosis.

Investigation of events committing cells to death revealed that a concealed NH2-terminal epitope of the pro-apoptotic protein Bak became exposed in vivo before apoptosis. This occurred after treatment of human Jurkat or CEM-C7A T-lymphoma cells with the mechanistically disparate agents staurosporine, etoposide or dexamethasone. The rapid, up to 10-fold increase in Bak-associated immunofluorescence was measured with epitope-specific monoclonal antibodies using flow cytometry and microscopy. In contrast, using a polyclonal antibody to Bak, immunofluorescence was detected both before and after treatment. There were no differences in Bak protein content nor in subcellular location before or after treatment. Immunofluorescence showed Bcl-xL and Bak were largely associated with mitochondria and in untreated cells they coimmunoprecipitated in the presence of nonioinic detergent. This association was significantly decreased after cell perturbation suggesting that Bcl-xL dissociation from Bak occurred on exposure of Bak's NH2 terminus. Multiple forms of Bak protein were observed by two dimensional electrophoresis but these were unchanged by inducers of apoptosis. This indicated that integration of cellular damage signals did not take place directly on the Bak protein. Release of proteins, including Bcl-xL, from Bak is suggested to be an important event in commitment to death.

Apoptosis↗
PubMed1993

Transrectal ultrasound appearances of granulomatous prostatitis.

Granulomatous prostatitis is an unusual, but well-recognized entity frequently mistaken for carcinoma on both digital rectal examination and transrectal ultrasound. The ultrasonographic findings of 11 patients with histologically-proven granulomatous prostatitis are reviewed.

Adult↗
PubMed1993

Side effects and patient acceptability of transrectal biopsy of the prostate.

The side effects and patient acceptability of 230 ultrasound guided prostatic needle biopsies performed by the transrectal route in an out-patient setting were reviewed retrospectively. Most of the side effects were transient and mild; one patient required hospitalization for urinary retention. Patient acceptability was good; over 70% of patients reported no significant pain from the biopsy procedure.

Biopsy, Needle↗
PubMed1993

Prostatic 'capsule'--a comparative study of histological and ultrasonic appearances.

The histological and transrectal ultrasound (TRUS) appearances at corresponding sites of the periphery of the prostate gland have been compared in 30 benign and 27 malignant glands taken at autopsy. In the benign series, the histological capsule was frequently absent and correlated poorly with the consistent TRUS findings of a regular, well-defined 'ultrasonic capsule'. It is concluded that 'the capsule' should be replaced as a tumour-staging landmark by a more realistic terminology. Carcinoma may be described as intra- or extra-prostatic, or confined or unconfined with respect to the gland. In the malignant glands, there was no correlation between morphologically unconfined cancers and irregular or absent ultrasound 'capsule' when corresponding areas were compared. This disparity must contribute to an underestimation of tumour extent with TRUS.

Humans↗
PubMed1992

Volume of normal prostate, of prostate cancer, and of benign prostatic hyperplasia: are correlations with prostate specific antigen clinically useful?

This retrospective study correlated prostate volume, determined by transrectal ultrasonography, with serum prostate specific antigen (PSA), by Deming regression analysis, in patients with confirmed benign prostatic hyperplasia (BPH) and patients with non-metastatic (M0) or metastatic (M1) prostate cancer. In BPH, a highly significant correlation was found between log10[PSA] and prostate volume. When this PSA/volume regression pattern for BPH was used as a reference standard, all 17 patients with M1 prostate cancer and 83% of the 23 patients with M0 disease were discriminated from BPH.

Aged↗
PubMed1992

Inter-relation between measurement of serum prostatic specific antigen and transrectal ultrasound in the diagnosis of benign prostatic hyperplasia and prostatic cancer.

Serum prostatic specific antigen (PSA) and ultrasound-determined prostatic volume (UPV) were measured in 50 patients with histologically proven benign prostatic hyperplasia (BPH) and in 40 patients with histologically proven prostatic cancer of whom 17 had evidence of distant metastases (M1) and 23 did not (M0). A good correlation between log PSA and UPV was demonstrated in the BPH group and rearrangement of the linear regression equation allowed calculation of a single variable--the log PSA corrected to a standard prostate volume for any given individual. A volume-corrected PSA correctly identified all patients with M1 disease and greatly improved but did not eliminate overlap of M0 disease with BPH. Reduction of serum PSA to a single volume-corrected variable will allow the introduction of practical and optimum protocols for the management of patients with prostatic enlargement.

Aged↗
PubMed1991

Transrectal ultrasound of the ejaculatory apparatus.

Most interest in transrectal ultrasound (US) of the prostate has concentrated on its role in the diagnosis and management of prostatic cancer. The increasingly detailed investigation of male patients with infertility has recently led to interest in the use of US in investigating the structure and function of the ejaculatory ducts and seminal vesicles. The anatomy and pathology of the ejaculatory ducts and seminal vesicles as demonstrated by transrectal US are discussed and illustrated.

Ejaculatory Ducts↗
PubMed1990

Transrectal ultrasound in the investigation of haemospermia.

The transrectal ultrasound findings in 52 patients with haemospermia were reviewed. Scan abnormalities were demonstrated in 43 patients (83%). These included benign prostatic hyperplasia (24 patients), seminal vesicle abnormalities (10 patients), prostatic calcification (32 patients) and two patients with prostatitis. No patient was proven to have prostatic malignancy. Transrectal ultrasonography can suggest a cause of haemospermia in the majority of patients without resort to invasive investigations, and can exclude underlying prostatic malignancy. It is recommended as the first radiological investigation in patients presenting with haemospermia.

Adult↗
PubMed1990

Experience with ultrasound guided transperineal prostatic needle biopsy 1985-1988.

A consecutive series of 143 ultrasound guided biopsies of the prostate have been analysed. In 84 patients, in whom carcinoma was suspected by both digital examination and ultrasound, 49 cancers were confirmed histologically. In 29 patients in whom digital examination suggested cancer but ultrasound was normal, 2 cancers were confirmed. In 20 patients with a normal digital examination but a suspicious ultrasound appearance, no cancers were proven.

Adenocarcinoma↗
PubMed1990

Origin and structure of benign prostatic hyperplasia.

The development of microradiography of the prostate gland has provided a new approach to investigating the origin and structure of benign hyperplasia. It has demonstrated that benign prostatic hyperplasia is usually microadenomatous in structure, although reticular types do occur. It originates at the lateral boundary of the periurethral muscle in the position of the transitional zone. In contrast, stromal nodules are homogeneous and amorphous in structure and develop at the site of the short straight urethral ducts within the periurethral muscle.

Adolescent↗