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W Gregory

Publications and source records attributed to W Gregory.

At least 19 recordsLinked to original sources
PubMed1997

The phosphorylation of bovine DNase I Asn-linked oligosaccharides is dependent on specific lysine and arginine residues.

The secretory glycoprotein DNase I acquires mannose 6-phosphate moieties on its Asn-linked oligosaccharides, indicating that it is a substrate for UDP-GlcNAc:lysosomal enzyme N-acetylglucosamine-1-phosphotransferase (phosphotransferase) (Cacia, J., Quan, C., and Frenz, J. (1995) Glycobiology 4, 99). Phosphotransferase recognizes a conformation-dependent protein determinant that is present in lysosomal hydrolases, but absent in most secretory glycoproteins. To identify the amino acid residues of DNase I that are required for interaction with phosphotransferase, wild-type and mutant forms of bovine DNase I were expressed in COS-1 cells and the extent of oligosaccharide phosphorylation determined. Phosphorylation of DNase I oligosaccharides decreased from 12.6% to 2.3% when Lys-50, Lys-124, and Arg-27 were mutated to alanines, indicating that these residues are required for the basal level of phosphorylation. Mutation of lysines at other positions did not impair phosphorylation, demonstrating the selectivity of this process. When Arg-27 was replaced with a lysine, phosphorylation increased to 54%, showing that phosphotransferase prefers lysine residues to arginines. Mutation of Asn-74 to a lysine also increased phosphorylation to 50.3%, and the double mutant (R27K/N74K) was phosphorylated 79%, equivalent to the values obtained with lysosomal hydrolases. Interestingly, Lys-27 and Lys-74 caused selective phosphorylation of the neighboring Asn-linked oligosaccharide. Finally, mutation of Lys-117 to an alanine stimulated phosphorylation, demonstrating that some residues may be negative regulators of this process. We conclude that selected lysine and arginine residues on the surface of DNase I constitute the major elements of the phosphotransferase recognition domain present on this secretory glycoprotein.

Amino Acid Sequence↗
PubMed1996

Cyclin D1 and prognosis in human breast cancer.

We have used immunohistochemical staining to assess the expression of cyclin D1 in formalin-fixed sections of 345 breast carcinomas, dating back 20 years. Clinical follow-up data were available on all patients. Approximately 50% of the tumours showed excessive nuclear staining for cyclin D1 as compared with normal epithelium. Some tumours showed strong cytoplasmic staining in the absence of nuclear staining, and around 25% of the tumours were judged to be negative for nuclear cyclin D1. Contrary to expectations, moderate/strong staining for cyclin D1 was associated with improved relapse-free and overall survival relative to patients whose tumours stained weakly or negatively. Conversely, tumours that were considered negative for cyclin D1 staining had an adverse prognosis, and the poor outcome was further accentuated if the tumours were also oestrogen receptor-negative. A possible explanation for our findings is that tumours in which cyclin D1 levels are abnormally low may have sustained mutations in other genes, such as RBI and that it is this abnormality that has the more significant impact on survival from breast cancer.

Adult↗
PubMed1995

Cyclical tumour variations in premenopausal women with early breast cancer.

The hormonal milieu at the time of tumour excision may have a significant impact on survival in premenopausal patients with breast cancer, with those undergoing surgery between days 3 and 12 of the menstrual cycle having a worse prognosis. To investigate possible mechanisms which might explain this finding, histological features of tumours from 363 patients included in two studies from Guy's Hospital have been reviewed. Axillary nodal involvement occurred in 71/115 (62%) of patients whose primary tumour was excised between days 3 and 12 of the cycle, compared with 116/248 (47%) of patients undergoing surgery at other phases of the cycle (chi 2 = 7.04, P < 0.01). Vascular invasion was observed in 54/115 (47%) of primary tumours removed between days 3 and 12 and 82/248 (33%) of tumours removed at other times (chi 2 = 6.47, P < 0.02). Multivariate analysis of factors influencing survival indicated that both axillary nodal status and phase of the cycle were highly significant independent predictors of prognosis.

Breast Neoplasms↗
PubMed1995

Myeloma during a decade: clinical experience in a single centre.

One hundred and fifty-six patients with multiple myeloma were treated over a period of 12 years at St. Bartholomew's Hospital. The progress of the disease was affected in 96/156 patients (61%). Response was defined as achieving a plateau of M component. A partial or complete response was seen in 68/120 patients treated conventionally (56.5%), and in 28/36 patients treated with high-dose therapy (77.7%). The median survival of the group as a whole was 20 months, with a 2-year survival of just over 40%. In the 36 patients treated with high-dose therapy, median survival was 6 years, and in a small group who have had maintenance Interferon therapy, the median has not yet been reached. In a univariate analysis, age, intensity of therapy, haemoglobin and creatinine levels were significant, but multivariate analysis showed that only age and intensity of therapy were independent predictors for survival. The outlook for relapsed patients who showed progression of disease remains poor, but palliation was best achieved by steroid and Interferon in combination. Patients who achieve complete responses and are maintained on Interferon appear to be doing better both in terms of freedom from symptoms and in survival, and methods to enable an elderly population to tolerate this form of therapy need to be explored.

Adult↗
PubMed1995

Long-term refraction and keratometry after penetrating keratoplasty for keratoconus.

We looked for continued corneal ectasia after penetrating keratoplasty (PK) for keratoconus by measuring long-term changes in keratometry and refraction after final suture removal. The records of 587 patients who had had PK for keratoconus and who had attended a single center over a 7-year period were examined. For 184 eyes keratometry or refraction data were available from the first operated eye from the 6-month interval after final suture removal, and, in these patients, these readings were repeated as they continued to be seen for review. The changes in mean keratometry, spherical equivalent, and cylinder over the period of follow-up were then calculated, and these data were assessed by regression analysis. We found no significant change with time in the amount of cylinder when measured by either refraction or keratometry. There was a trend (p = 0.075) toward an increase in the mean keratometry with time, suggesting a gradual flattening of the cornea, and there was a clinically small, but statistically significant (p < 0.001), time-dependent increase in the residual myopia in the years after final suture removal. In conclusion, we found a wide range in the individual values for changes in keratometry or refraction in the years after suture removal following PK for keratoconus but no evidence overall to suggest continued corneal ectasia or a recurrence of keratoconus in these grafts.

Cornea↗
PubMed1994

Herpes simplex virus glycoprotein D acquires mannose 6-phosphate residues and binds to mannose 6-phosphate receptors.

Herpes simplex viruses (HSV) use multiple and sequential receptors to enter host cells. HSV glycoprotein D (gD) has been implicated in binding to cellular receptors that facilitate virus penetration into cells. We used soluble forms of gD that were expressed in Chinese hamster ovary cells to characterize and identify a putative cellular receptor for HSV as the 275-kDa mannose 6-phosphate/insulin-like growth factor II receptor. Soluble gD also bound to the 46-kDa cation-dependent mannose 6-phosphate (Man-6-P) receptor and was extensively modified with Man-6-P residues on its Asn-linked oligosaccharides. Additionally, soluble gD was a high affinity substrate for N-acetylglucosamine-1-phosphotransferase, the first enzyme in the biosynthetic pathway for the addition of Man-6-P residues to lysosomal enzymes. The membrane form of gD immunoprecipitated from HSV-infected cells also bound to the 275-kDa mannose 6-phosphate/insulin-like growth factor II receptor, albeit poorly, and only a small fraction of the membrane gD was modified with Man-6-P. Notwithstanding this low level of mannose phosphorylation, the interaction between gD and Man-6-P receptors may play a role in some aspect of virus entry or egress.

Amino Acid Sequence↗
PubMed1994

Long-term functional outcome after early surgery compared with laser and medicine in open-angle glaucoma.

PURPOSE: This randomly allocated prospective clinical study was designed to assess the relative efficacy of laser trabeculoplasty, medical therapy, and trabeculectomy used as the primary treatment in open-angle glaucoma, with particular regard to the level of intraocular pressure control and the amount of visual field decay. No patient had received any antiglaucoma treatment before entry into the trial. METHODS: One hundred sixty-eight patients were entered into the trial and randomly allocated into one of the three treatment groups--laser, medicine, or surgery. Follow-up was for a minimum of 5 years. The patients were monitored in the standard way, including intraocular pressure estimations and visual field tests (initially using the Friedmann analyzer and later including Humphrey automated perimetry). RESULTS: Despite similar initial composition of the three treatment groups, primary surgery resulted in the lowest mean intraocular pressures. The perimeter Friedmann visual fields were shown to have deteriorated in patients in the medicine-treated group and to a lesser extent in patients in the laser-treated group, but not in patients in the surgery-treated group. Multivariate linear regression analysis showed that the difference in field changes between laser and surgical treatments could be explained entirely by the difference between the intraocular pressure values at 6 months between the two groups. The same was not true for the medicine-treated group. CONCLUSION: Primary trabeculectomy appears to have the desired effect in preserving visual function in patients with high-tension glaucoma. This may be related to laser treatment might be expected to have the same effect.

Aged↗
PubMed1994

Distribution and aetiology of blindness and visual impairment in mesoendemic onchocercal communities, Kaduna State, Nigeria. Kaduna Collaboration for Research on Onchocerciasis.

During a field trial of ivermectin in Kaduna State, 6831 people age 5 years and above, living in 34 mesoendemic onchocercal communities in Kaduna State, northern Nigeria, were examined for ocular disease. Visual function assessments included tests of visual acuity and visual fields. A total of 185 individuals (2.7%) were bilaterally blind by acuity criteria with a further 28 blind by field constriction. The overall prevalence of blindness was 3.1%. A further 118 individuals were visually impaired by WHO criteria. Examination for the cause of blindness revealed that 43% of eyes in bilaterally blind patients were blind due to onchocerciasis. A further 11% were blind from optic atrophy much of which was probably onchocercal in origin. Glaucoma was the next most common cause of blindness in the bilaterally blind (11%). Only 6% of eyes were blind from cataract as the primary cause. In the visually impaired population cataract was the most common primary cause of impaired/blind eyes (31%), followed by onchocerciasis (19%) [corrected].

Adolescent↗
PubMed1994

A randomized trial of two etoposide schedules in small-cell lung cancer: the influence of pharmacokinetics on efficacy and toxicity.

PURPOSE: Etoposide is a schedule-dependent drug, as demonstrated by the superiority of 5 consecutive daily infusions over a continuous 24-hour infusion in patients with small-cell lung cancer. A randomized trial has therefore been conducted to compare an extended 8-day regimen with the 5-day schedule. PATIENTS AND METHODS: Ninety-four patients with small-cell lung cancer (35 limited disease, 59 extensive disease) were randomized to receive single-agent etoposide 500 mg/m2, either as 5 daily 2-hour infusions of 100 mg/m2 or as 8 daily 75-minute infusions of 62.5 mg/m2, both repeated every 3 weeks for six cycles. Single-agent carboplatin was administered at relapse in both arms of the study. Patients were stratified at randomization according to extent of disease and Karnofsky performance status (KPS). RESULTS: The overall response rate was 81% in the 5-day arm and 87% in the 8-day arm, with median survival durations of 7.1 and 9.4 months, respectively (no significant differences). The time over which plasma etoposide exceeded low plasma concentrations was significantly longer in patients who responded compared with patients who did not respond. This was most significant for time at concentrations greater than 1, 1.5, and 2 micrograms/mL. Hematologic toxicity was significantly worse in the 5-day arm of the study (cycle no. 1 nadir neutrophil count, 0.8 x 10(9)/L v 1.7 x 10(9)/L). Stepwise regression analysis found duration of exposure to plasma etoposide greater than 3 micrograms/mL to be predictive of nadir neutrophil count and duration of exposure to plasma etoposide greater than 2 micrograms/mL to be predictive of nadir WBC count. CONCLUSION: The 5-day and 8-day regimens had equivalent activity in small-cell lung cancer. A pharmacokinetic association between concentrations of etoposide and response and toxicity was found. Antitumor activity was associated with the maintenance of lower levels of etoposide than found to be associated with hematologic toxicity. This supports the hypothesis that the schedule of etoposide administration may affect efficacy and toxicity, and that prolonged exposure to low concentrations of etoposide may improve the therapeutic ratio for this drug.

Adult↗
PubMed1993

Markers of prognosis in breast cancer--the relationship between binding of the lectin HPA and histological grade, SPF, and ploidy.

Abnormal cellular glycosylation as demonstrated by the binding of a lectin from Helix pomatia (HPA) to paraffin-embedded sections has been shown in several studies to be associated with aggressive biological behaviour and poor long-term patient prognosis in breast cancer. This study aims to address the possibility that expression of the HPA binding ligand may be of prognostic significance through an association with increased cellular proliferation (as measured by S-phase fraction and histological grade), anaplasia (reflected in histological grade), or ploidy (DNA index). In a 24 year retrospective study, paraffin-embedded sections of 366 primary breast cancers were stained for binding of HPA. All tumours were assessed for histological grade. Flow cytometry was performed on all cases for which sufficient tumour tissue was available (358/366 cases) and S-phase fraction (SPF) and ploidy calculated. Data regarding patient age at diagnosis, nodal status, and tumour size were also recorded. Life table analyses revealed survival advantage for HPA 'non stainers' in comparison to 'stainers' (p < 0.001); for patients with tumours of low grade vs. high grade (p < 0.001); and for those with tumours of low SPF vs. high SPF (p < 0.001). No survival advantage was shown for those with diploid vs. aneuploid tumours (p = 0.17). No association was apparent between HPA binding and grade, SPF, or ploidy (Chi squared values not significant). This was confirmed by multivariate analysis in which nodal status, tumour size, and SPF were independently predictive of survival. There was no confounding effect of grade, SPF, or ploidy upon the correlation between survival and HPA binding. HPA was, however, not independently predictive owing to its strong association with nodal status. The results of this study suggest that the prognostic significance of altered glycosylation, as detected by HPA binding, is unlikely to be through an association with proliferative rate, degree of anaplasia, or cellular ploidy, but may rather be through a direct association with the presence of nodal metastases.

Breast Neoplasms↗
PubMed1993

Radiographic patterns of intrathoracic disease in breast carcinoma: prognostic implications.

The chest radiographic appearances of patients with intrathoracic metastases from breast cancer are variable and their relationship to patient outcome is unknown. This study aimed to classify and determine the frequency of various radiographic patterns and, in addition, to establish whether these patterns can be used to predict patient prognosis. A retrospective study was made of the patients of a major breast unit who over a 3 year period were found to have developed intrathoracic metastases. In each case, the earliest plain chest X-ray showing signs of metastasis was reviewed and the frequency of the different radiographic patterns determined. Comparison was made between these patterns and patient mortality. The chest radiographs of 92 patients who developed intrathoracic metastases during a 3 year period were analysed. Pulmonary nodules were found in 66%, pleural effusions in 41% (bilateral in 18%), lymphadenopathy in 25%, lymphangitis in 18% and pleurally-based nodules in 11%. Median survival of the whole group was 13.5 months. Patients with bilateral, but not unilateral, effusions had a significantly poorer prognosis (median survival 3 months). Although the median survival of patients with lymphangitis seemed poor (5.5 months), this difference was not statistically significant. Multivariate analysis showed bilateral effusions to be the only independent predictor of worse outcome. We have found that of the plain radiographic patterns seen in intrathoracic metastasis from breast cancer, only bilateral pleural effusions can be used to predict a worse prognosis than that associated with intrathoracic metastasis as a whole.

Adult↗
PubMed1993

Combination chemotherapy for intermediate and high grade non-Hodgkin's lymphoma.

One hundred and eighteen consecutive adults with newly diagnosed intermediate and high-grade non-Hodgkin's lymphoma were treated with chemotherapy comprising Doxorubicin, Cyclophosphamide, Vincristine and Prednisolone with mid-cycle Methotrexate (MTX) and leucovorin rescue ('CHOP-M'). Intrathecal MTX was given with each treatment cycle as central nervous system (CNS) prophylaxis. 'Clinical remission' was achieved in 70/110 evaluable patients (64%), complete remission: 45/110, (41%), good partial remission: 25/110 (23%). Twenty two patients (19%) died prior to completion of therapy, 18 patients had persistent disease. Hyponatremia (< 137 mmol l-1), advanced age and hypoalbuminaemia (< 32 g l-1) correlated adversely with achievement of CR (P = 0.0007, 0.0005 and 0.04 respectively). With a minimum follow up of 41 years, 47 of the seventy patients (67%) in whom clinical remission was achieved remain well, 19 have developed recurrent disease, resulting in an actuarial projected remission duration of 70% at 8 years. Four died in CR. There has been only one isolated CNS recurrence. On univariate analysis, hypoalbuminaemia, hyponatremia and beta 2 microglobulin (> 3) correlated with unfavourable outcome in terms of duration of remission (P = 0.0009, 0.007 and 0.04 respectively). On multivariate analysis, only the serum sodium (0.002) and advanced age (0.01) were predictive for remission duration. Fifty patients (45%) are alive, the overall actuarial projected survival is thus 42% at 8 years. On univariate analysis, age, hypoalbuminaemia, hyponatraemia, liver involvement and the presence of B symptoms correlated unfavourably with survival. On multivariate analysis, hypoalbuminaemia, advanced age, hyponatraemia, male gender (aged > 50) and diffuse large cell or large cell, immunoblastic histology (Working Formulation) had an adverse effect (P = 0.003, < 0.0001, < 0.0001, 0.002, and 0.03). It was further possible, using cut-off points of 32 g l-1 and 136 mmol l-1 for albumin and sodium respectively to define prognostic categories for patients who differed significantly in terms of survival.

Adolescent↗
PubMed1993

Patterns of survival in patients with Hodgkin's disease: long follow up in a single centre.

BACKGROUND: Prolonged remission can now be induced in the majority of patients with Hodgkin's disease with chemotherapy and/or irradiation. However, there is a significant proportion of patients in whom this approach fails, either at presentation or subsequently. Survival is the definitive endpoint to assess treatment efficacy. In this study, the survival patterns of a large group of consecutive patients treated in a single institution are presented. RESULTS: The overall median survival was 18.3 years. Clinical remission (complete remission plus good partial remission) was induced in 443 (85%); the median survival of patients in remission has not been reached. Fifty-eight patients achieved responses less than clinical remission with initial therapy (partial response) or had progressive disease, the median survival of this group being 1.4 years. With further therapy, remission was subsequently induced in 10; 5 are still alive, 5 have died between 1.9 years and 14.3 years. Twenty patients died before completion of therapy. Recurrence has been documented in 147 of the patients in remission (following initial therapy) over a median follow up period of 13 years (minimum 5 years). One hundred forty-three of these patients were retreated following recurrence (105 chemotherapy, 28 radiotherapy, 6 combined modality treatment and 4 surgery). Second remission was induced in 109/143 (76%). There was a trend towards better second remission induction in patients whose first remission was longer than 1 year (p = 0.06). The median duration of second remission was inferior to first remission duration (p < 0.001). There was no correlation between duration of first remission and survival following recurrence (p = 0.8) or with duration of second remission (p = 0.54). There was no significant difference in duration of second remission between patients who were initially treated with radiotherapy or chemotherapy (p = 0.3). The median survival following second remission was 12.0 years, being the same for patients with initially localized disease (stages I and II) treated with radiation alone and for patients with advanced Hodgkin's disease (stages III and IV) treated with chemotherapy. Survival after recurrence is significantly better for patients under 50 years at the time of recurrence (p < 0.001). Second recurrence was documented in 46 patients, third remission being reinduced in 22, the median survival of the latter being 5.1 years. CONCLUSION: These results illustrate the importance of prolonged follow up in defining the clinical course of patients with HD and are vital for planning experimental chemotherapy at the time of treatment failure or recurrence.

Adolescent↗
PubMed1992

Characterization of the signal for rapid internalization of the bovine mannose 6-phosphate/insulin-like growth factor-II receptor.

The signal for rapid internalization of the mannose 6-phosphate/insulin-like growth factor II receptor has been localized to the sequence Tyr-Lys-Tyr-Ser-Lys-Val in positions 24-29 of its 163-residue cytoplasmic tail. Most of the activity of this signal is mediated by the carboxyl 4 amino acids, especially Tyr26 and Val29 (Canfield, W. M., Johnson, K. F., Ye, R. D., Gregory, W. and Kornfeld, S. (1991) J. Biol. Chem. 266, 5682-5688). In this study, we have tested the effect of a series of mutations on the internalization rate of a mutant receptor that contains a 29-amino acid cytoplasmic tail terminating with the 4-amino acid internalization sequence Tyr-Ser-Lys-Val. Replacement of Tyr26 with Phe or Trp gave rise to mutant receptors that were internalized at 10% the wild-type rate, while receptors with Ala, Leu, Ile, Val, or Asn at this position were totally inactive. Val29 could be replaced by other large hydrophobic residues (Phe, Leu, Ile, or Met) with no loss of activity, but the presence of Ala, Gly, Arg, Gln, or Tyr in this position inactivated the signal. Ser27 could be effectively replaced by many different amino acids, but not by Pro or Gly. However, Gly27 could be tolerated if the residues at positions 28 and 29 were also changed. A change in the 2-residue spacing between Tyr26 and Val29 destroyed the signal. These data show that the essential elements of this signal are an aromatic residue, especially a Tyr in the first position, separated from a large hydrophobic residue in the last position by 2 amino acids. The residues in positions 2 and 3 of the signal may have a modulating effect on its activity. The Tyr-Ser-Lys-Val signal could be moved to a more proximal region of the cytoplasmic tail with only a modest loss of activity. In addition, the signal could be effectively replaced by the putative 4-residue signals of seven other receptors and membrane proteins known to undergo rapid endocytosis, including the Tyr-Thr-Arg-Phe sequence of the transferrin receptor, a Type II membrane protein. These results are compatible with the 4-residue signals of this type being interchangeable, even among Type I and Type II membrane proteins.

Amino Acid Sequence↗
PubMed1992

Clinical pharmacokinetics of epirubicin: the importance of liver biochemistry tests.

The influence of liver biochemistry tests on epirubicin pharmacokinetics has been investigated in 52 women with advanced breast cancer, 27 of whom had radiologically proven liver metastases. Patients received epirubicin 12.5-120 mg m-2 given as an i.v. bolus. Epirubicin levels were measured by HPLC following the first cycle of treatment. Epirubicin elimination, expressed as clearance (dose/AUC), in the 22 patients with normal AST and bilirubin was compared with that of 30 patients with a raised AST +/- raised bilirubin. Epirubicin clearance was significantly reduced in the patients with a raised AST, whether their serum bilirubin was normal (22 patients) or elevated (eight patients). In the 30 patients with a raised AST +/- raised bilirubin, epirubicin clearance correlated strongly with the level of AST (r = -0.72) but not with serum bilirubin, alkaline phosphatase, albumin or creatinine. Using a multiple regression analysis, AST was the only one of these biochemical variables predictive of epirubicin clearance (r2 = 0.47, P = 0.0006). We conclude that a raised serum AST is a more sensitive and reliable measure of abnormal epirubicin pharmacokinetics than increased bilirubin. These findings have implications for anthracycline treatment in patients with abnormal liver biochemistry.

Adult↗
PubMed1992

Patterns of survival in patients with advanced Hodgkin's disease (HD) treated in a single centre over 20 years.

A total of 164 consecutive adults with newly confirmed stage IIIB, IVA or IVB Hodgkin's disease (HD) commenced cyclical combination chemotherapy comprising mustine, vinblastine, prednisolone and procarbazine (MVPP) every 6 weeks (145 patients) or minor variants (19) at St Bartholomew's Hospital between 1968 and 1984. The median follow-up period is 14 years. Complete remission (CR) was achieved in 97/164 (59%) and partial remission (PR) in 23/164 (14%) with lesser responses or death being documented in 44. Achievement of CR correlated with stage, serum albumin and serum beta2 microglobulin level at presentation on univariate and multivariate analysis; 55/97 (58%) remain in continuous CR, the median duration of remission not having been reached. Twelve patients died in first remission; there have been 30 recurrences, one occurring after 13 years. Second remission was achieved in 17/30; 6/17 remain in continuous second remission and two have died in second remission. There have been nine second recurrences, third remission being achieved in 6/9. Two continue in third remission, two patients have died in third remission: 82/164 patients are alive with a minimum follow-up of 6 years. Eighty-two patients have died; 66 with evidence of HD, six with second malignancy, one each of haemorrhage and infection, eight of unrelated causes, the cause of death was unknown in one. The overall median survival from presentation is 14 years, being the same for patients in CR and PR with minimal residual abnormality (good partial remission, GPR), and being better for those for whom remission was achieved than those for whom it was not. The median survival following first recurrence is 4 years, being significantly longer for younger patients (less than 50 years). These results emphasise the importance of long-term follow-up to determine the clinical course of HD and are vital for planning experimental chemotherapy at the time of early treatment failure or recurrence.

Adolescent↗
PubMed1992

The pharmacogenetics of chemical carcinogenesis.

The human body is endowed with a large number of xenobiotic chemical metabolizing enzymes, a significant proportion of which are polymorphic and thus render one individual at greater or lesser risk than another of chemically-induced disease. All examples of genetic polymorphism of chemical metabolizing enzymes have been reviewed in relation to their potential to activate and detoxicate procarcinogens and promutagens. Many examples are cited whereby phenotype can act as a carcinogenic risk factor. With the availability of a large amount of DNA sequence data for chemical metabolizing enzymes there has emerged a number of polymerase chain reaction (PCR) strategies aimed at discerning one metabolic phenotype or another. This is seen as a very positive and democratic scientific development, widening the franchise for studies of disease risk. Nevertheless, it is argued that, at these early stages with many laboratory-based scientists scarcely familiar with epidemiological study design, a cautious approach should obtain when interpreting single studies.

Animals↗