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Biomedical subjects

R Mallett

Publications and source records attributed to R Mallett.

At least 19 recordsLinked to original sources
PubMed2006

The importance of accurate pathological assessment of lymph node involvement in colorectal cancer.

This review presents an up-to-date analysis of the importance of accurate pathological lymph node staging in colorectal cancer. Lymph node staging is reliant on the technique of the surgeon and the pathologist as well as methods employed in the histopathology laboratory, and is vital for determining appropriate therapy. The significance of micrometastatic nodal disease is evaluated and new techniques for pathological evaluation are discussed. Recommendations for evaluation of lymph node status in colorectal cancer are provided based on current scientific evidence, and standardization of pathological dissection and laboratory handling is advocated.

Colorectal Neoplasms↗
PubMed2005

Pathways to care and ethnicity. 1: Sample characteristics and compulsory admission. Report from the AESOP study.

BACKGROUND: Many studies have found high levels of compulsory admission to psychiatric hospital in the UK among African-Caribbean and Black African patients with a psychotic illness. AIMS: To establish whether African-Caribbean and Black African ethnicity is associated with compulsory admission in an epidemiological sample of patients with a first episode of psychosis drawn from two UK centres. METHOD: All patients with a first episode of psychosis who made contact with psychiatric services over a 2-year period and were living in defined areas were included in the (AESOP) study. For this analysis we included all White British, other White, African-Caribbean and Black African patients from the AESOP sampling frame. Clinical, socio-demographic and pathways to care data were collected from patients, relatives and case notes. RESULTS: African-Caribbean patients were significantly more likely to be compulsorily admitted than White British patients, as were Black African patients. African-Caribbean men were the most likely to be compulsorily admitted. CONCLUSIONS: These findings suggest that factors are operating at or prior to first presentation to increase the risk of compulsory admission among African-Caribbean and Black African patients.

Adolescent↗
PubMed2005

Pathways to care and ethnicity. 2: Source of referral and help-seeking. Report from the AESOP study.

BACKGROUND: Previous research has found that African-Caribbean and Black African patients are likely to come into contact with mental health services via more negative routes, when compared with White patients. We sought to investigate pathways to mental health care and ethnicity in a sample of patients with a first episode of psychosis drawn from two UK centres. METHOD: We included all White British, other White, African-Caribbean and Black African patients with a first episode of psychosis who made contact with psychiatric services over a 2-year period and were living in defined areas. Clinical, socio-demographic and pathways to care data were collected from patients, relatives and case notes. RESULTS: Compared with White British patients, general practitioner referral was less frequent for both African-Caribbean and Black African patients and referral by a criminal justice agency was more common. With the exception of criminal justice referrals for Black African patients, these findings remained significant after adjusting for potential confounders. CONCLUSIONS: These findings suggest that factors are operating during a first episode of psychosis to increase the risk that the pathway to care for Black patients will involve non-health professionals.

Adolescent↗
PubMed2003

The effect of curing with plasma light on the shrinkage of dental restorative materials.

Commercially available light activated dental composites were used in this study to compare the shrinkage following curing with plasma light (Apollo95E, DMDS) and a convention halogen dental curing light (Prismetics Lite II, Dentsply). Polymerization shrinkage was determined by measuring the strain in one dimension by means of a contacting transducer. The percentage linear shrinkage were: Spectrum H = 1.84 + 0.31, P = 1.49 + 0.35*; Ana aesthetic H = 2.04 + 0.38, P = 1.85 + 0.27; Esthet.x H = 1.66 + 0.28, P = 1.69 + 0.25; Dyract AP H = 2.39 + 0.33, P = 2.18 + 0.35*; Apollo Restore H = 1.88 + 0.36, P = 1.42 + 0.33*; Surefil H = 0.88 + 0.28, P = 0.99 + 0.30 where * = significantly different, t-test at P < 0.05. The results suggested that there was less shrinkage when curing some, but not all, materials using the plasma light, although this could be attributed to a reduced level of polymerization.

Composite Resins↗
PubMed2001

A comparative evaluation of conventional and pretargeted radioimmunotherapy of CD20-expressing lymphoma xenografts.

Radioimmunotherapy with anti-CD20 monoclonal antibodies is a promising new treatment approach for patients with relapsed B-cell lymphomas. However, the majority of patients treated with conventional radiolabeled anti-CD20 antibodies eventually have a relapse because the low tumor-to-blood and tumor-to-normal organ ratios of absorbed radioactivity limit the dose that can be safely administered without hematopoietic stem cell support. This study assessed the ability of a streptavidin-biotin "pretargeting" approach to improve the biodistribution of radioactivity in mice bearing Ramos lymphoma xenografts. A pretargeted streptavidin-conjugated anti-CD20 1F5 antibody was infused, followed 24 hours later by a biotinylated N-acetylgalactosamine-containing "clearing agent" and finally 3 hours later by (111)In-labeled DOTA-biotin. Tumor-to-blood ratios were 3:1 or more with pretargeting, compared with 0.5:1 or less with conventional (111)In-1F5. Tumor-to-normal organ ratios of absorbed radioactivity up to 56:1 were observed with pretargeting, but were 6:1 or less with conventional (111)In-1F5. Therapy experiments demonstrated that 400 microCi (14.8 MBq) or more of conventional (90)Y-1F5 was required to obtain major tumor responses, but this dose was associated with lethal toxicity in 100% of mice. In marked contrast, up to 800 microCi (29.6 MBq) (90)Y-DOTA-biotin could be safely administered by the pretargeting approach with only minor toxicity, and 89% of the mice were cured. These data suggest that anti-CD20 pretargeting shows great promise for improving current therapeutic options for B-cell lymphomas and warrants further preclinical and clinical testing.

Animals↗
PubMed2000

A tetravalent single-chain antibody-streptavidin fusion protein for pretargeted lymphoma therapy.

Single-chain Fv antibody fragments from the CD20-specific murine monoclonal antibody B9E9 were genetically engineered as streptavidin fusions [single-chain Fv-streptavidin (scFvSA) fusion protein] for use in pretargeted radioimmunotherapy. The scFvSA constructs were expressed as soluble, tetrameric species in the periplasm of Escherichia coli. Expression levels were affected by the order of the variable regions and the length and composition of the single-chain Fv linker. The best expressor was obtained with the variable regions in the heavy chain-light chain configuration separated by a 25-mer Gly4Ser linker. This construct produced 250-300 mg of soluble, tetrameric fusion protein per liter of fermentor culture. The fusion protein (Mr 173,600) was purified from crude lysates by iminobiotin affinity chromatography with an overall yield of about 50% and was analyzed for functionality both in vitro and in vivo. Immunoreactivity of the scFvSA fusion protein and its nanomolar affinity to CD20-positive Ramos cells were comparable with the B9E9 monoclonal antibody. The fusion protein had a biotin dissociation rate identical to recombinant streptavidin and bound an average of 3.6 biotins/molecule of a possible 4 biotins/molecule. Labeled fusion protein cleared from the blood of BALB/c mice with a P half-life of about 16 h. In nude mice bearing Ramos xenografts, the fusion protein demonstrated sufficient tumor localization of functional streptavidin to enable efficient, tumor-specific targeting of a subsequently administered radionuclide-chelate/biotin molecule. These results suggest that large quantities of functional scFvSA can be produced for clinical testing as a therapy for non-Hodgkin's lymphoma.

Amino Acid Sequence↗
PubMed2000

Factors in the onset of schizophrenia: a comparison between London and Trinidad samples.

OBJECTIVE: Sociodemographic factors play an important role in the genesis of mental disorders. High rates of unemployment and other social factors have been reported previously among African-Caribbeans with schizophrenia in London. The aim of the present study was to compare these factors in Trinidad with London African-Caribbeans. METHOD: Using internationally defined criteria, patients with first-onset schizophrenia were recruited in both countries, and information on the onset of symptoms, help-seeking, pathways into care, premorbid personality and educational and employment status were collected. These two samples are compared on a number of these factors. A total of 56 cases of first onset of psychosis coming into contact with psychiatric services in Trinidad were studied. Of these, 46 cases were diagnosed as having schizophrenia using the CATEGO program. Over a period of 2 years, 38 African-Caribbean patients with schizophrenia were recruited in London. RESULTS: African-Caribbean patients with schizophrenia in London were more likely to be admitted for perceived threat to others and to have shown loss of interest and serious neglect and to have assaulted others. A lower proportion were admitted via a psychiatrist and a higher proportion by the police. The unemployment rate among the London sample of African-Caribbeans was much higher than that in the general population, whereas this was not the case for the Trinidad patients. CONCLUSION: These findings are discussed in the context of culture and aetiology of schizophrenia, and suggestions with regard to future research are made.

Adult↗
PubMed1999

Early manifestations, personality traits and pathways into care for Asian and white first-onset cases of schizophrenia.

BACKGROUND: Previous studies have shown that manifestations of symptoms and premorbid personality of patients with schizophrenia differ across cultures. However, these have only been demonstrated in cultural settings apart from each other. METHOD: We set out to compare these across different ethnic groups from a catchment area in west London. The Asian and the white group had similar inception rates of schizophrenia and we therefore decided to compare these two groups to ascertain similarities in social, demographic and personality factors and pathways into care. First-onset cases of schizophrenia were studied on a number of parameters using previously validated instruments. RESULTS: There were more similarities than differences between the two groups. When compared with the findings of a previous multicentre study in India, London Asians, like their counterparts in India, were more likely than the London white sample to present with loss of appetite, become more religious and behave as if hearing voices. However, compared to their Indian counterparts, the onset of symptoms was more likely to be insidious and alternative sources of healing were less likely to be approached. CONCLUSIONS: These findings are discussed in relation to the findings for white patients and recommendations made for future research.

Adult↗
PubMed1999

Life events, ethnicity and perceptions of discrimination in patients with severe mental illness.

BACKGROUND: Whilst it is commonly believed that black and ethnic minority (B&EM) people living in the UK experience social disadvantage compared with the white British (WB) population, no study has specifically addressed this issue in patients with severe mental illness. We sought to test the hypothesis that B&EM patients experience more negative life events than their WB counterparts, and to examine the extent to which they attribute these events to discrimination. METHOD: Thirty-four WB, 78 African Caribbean (AC) and 35 other ethnic minority patients with psychotic illnesses, defined using Research Diagnostic Criteria, were asked to complete a Racial Life Event Questionnaire examining life events and perceptions of discrimination at baseline and 12 and 24 months later. RESULTS: African Caribbean patients experienced more 'Financial' life events across the study period, otherwise there were no significant differences between patient groups in number of life events experienced. The B&EM group collectively (n = 113), however, were significantly more likely than the WB group (n = 34) to attribute 'Assault', and 'Legal' life events to discrimination. The AC patient group were significantly more likely than the other two ethnic groups to attribute the 'Financial' and 'Health' life events they experienced to discrimination. The B&EM group was also significantly more likely, and particularly the AC patient group, to report that members of their own ethnic group are adversely affected by discrimination. Further analyses showed skin colour rather than ethnicity or nationality to be the major contributing factor to perception of discrimination; thus, the Irish (n = 11) had similar scores to the WB while Africans (n = 16) scored like the ACs. CONCLUSION: Our study shows that B&EM patients do not experience significantly more life events than WB patients; however, their perception of these events is clearly different, and significantly more often attributed to racism. It is reasonable to suppose that patients may be disinclined to utilise services they believe to be prejudiced against them on the basis of their skin colour, and service providers need to be aware of this in order to create health care services that B&EM patients feel confident to use.

Adult↗
PubMed1999

Fertility and marital rates in first-onset schizophrenia.

BACKGROUND: Many studies have demonstrated that in schizophrenia there are decreased rates of marriage, fertility and marital fertility. However, it is not clear whether this finding occurs as a social consequence of having the illness or is an inherent part of the illness. One would expect it to vary across cultures if it were being mediated by social and cultural factors. METHOD: We investigated this by reviewing the marital and fertility data from a multi-ethnic first-contact group of patients in London with CATEGO broadly defined schizophrenia, and comparing this with similar data from a group of controls who were matched for age, gender and ethnicity. RESULTS: Our sample comprised 38 White British, 38 Caribbean and 24 Asian subjects. The Asian group were significantly older (mean age 38, P < 0.003) and had a greater percentage of females (50%). When compared to controls, the White and Caribbean patients, but not the Asians, had decreased marital and stable relationship rates. There was also decreased fertility and marital fertility as evidenced by number of children among the Whites and Caribbeans, but again significantly not among the Asians. Marital status did not predict fertility rates, particularly among the Caribbeans. Regression analysis demonstrated an effect for age on the number of children but not on marital status. CONCLUSIONS: These findings suggest that marital and reproductive behaviour are reduced in schizophrenia, but this effect may be mediated by social and cultural factors and therefore not apply consistently across ethnicity. Further research is needed to prospectively investigate populations to determine whether impairments of this nature are inherent or consequential to the illness.

Adolescent↗
PubMed1999

The first contact of patients with schizophrenia with psychiatric services: social factors and pathways to care in a multi-ethnic population.

BACKGROUND: African-Caribbean patients have less desirable routes of entry into the psychiatric services than other ethnic groups in Britain but this may not apply to the first contact with services. METHODS: Patients' pathways to care, type of admission or referral and sectioning details were recorded for all first contact patients presenting to south London psychiatric services over a 2-year period. We also conducted a retrospective analysis of data from the Camberwell Register, comparing rates of compulsory admission between 'Whites' and 'African-Caribbeans' for first and readmissions, over a 20-year period. RESULTS: Our first contact sample comprised 38 White, 38 African-Caribbean and 24 Asian patients with CATEGO defined broad schizophrenia. GP referral was found to be the most common mode of contact and there were no significant differences between the ethnic groups with regard to compulsory admission. Similarly, data from the Camberwell Register showed no significant difference in rates of compulsory admission between first admission White and African-Caribbean patients. However, when all readmissions were examined, African-Caribbeans were more likely to be admitted involuntarily. CONCLUSIONS: Our findings suggest that reports of less desirable routes of entry for African-Caribbean patients into the psychiatric service do not apply to their first admission but are likely to develop over time and repeated contact with the services.

Adolescent↗
PubMed1999

Social factors and first onset schizophrenia among Asians and whites.

Previous studies from the Indian subcontinent had suggested that the onset and outcome of schizophrenia is linked with social factors. We set out to study the inception rates and social factors in whites and Asians who were presenting for the first time ever to various catchment facilities in Ealing catchment area. A total of 62 cases (38 white and 24 Asians) were diagnosed as having schizophrenia. Using well established and previously validated standardised instruments we collected information on various social factors and inception rates of schizophrenia. The inception rates and social factors were largely similar in these two groups. By and large the social factors in the two groups were broadly similar except that Asians were significantly more likely to show increased religious activity compared with their white counterparts. Contrary to previous findings Asians were more likely to have had longer duration of symptoms prior to seeking help. These findings are discussed in relation to Asian support systems and suggestions made for future research.

Adult↗
PubMed1999

First-contact incidence rate of schizophrenia on Barbados.

BACKGROUND: The incidence rate for broad schizophrenia among second-generation African-Caribbean people in the United Kingdom has been reported as high. Ethnicity, migration and psychosocial stressors have been suggested as causal factors. AIMS: To determine the incidence of schizophrenia for the whole population of Barbados using an identical methodology to two previous studies in Trinidad (Bhugra et al, 1996) and London (Bhugra et al, 1997). METHOD: A 12-month study of all persons in the 18-54-year age group presenting with a psychosis for the first time was carried out on the population of Barbados. Information was collected using World Health Organization screening and measurement instruments. RESULTS: On an island of just over a quarter of a million, 40 out of the 53 patients that met the inclusion criteria were categorised as S+ (narrow) schizophrenia, giving an incidence rate of 2.8/10,000 (95% CI 1.97-3.7). The incidence rate for broad schizophrenia was calculated at 3.2/10,000 (95% CI 2.3-4.1), which is significantly lower than the comparable rate for London's African-Caribbeans of 6.6/10,000 (95% CI 4.5-8.7). CONCLUSIONS: The very high rate for broad schizophrenia among African-Caribbean people in the UK is probably due to environmental factors.

Adolescent↗
PubMed1997

Incidence and outcome of schizophrenia in whites, African-Caribbeans and Asians in London.

BACKGROUND: Several previous studies have indicated high rates of schizophrenia in African-Caribbeans in the UK compared to White population. METHOD: All people aged 18 to 64 years residing in two health districts in London who made contact with hospital or community services over a 1-year (Whites) or 2-year (ethnic minorities) period were screened for psychotic symptoms. RESULTS: One hundred and twenty-three patients passed the screen, of whom 100 were assigned a schizophrenic class by the CATEGO program. Of these, 38 were White, 38 African-Caribbean and 24 Asian. The incidence rate for broad schizophrenia was significantly higher for African-Caribbeans than for Whites. Asians showed a high rate among people age 30 and over, particularly women. Poor outcome at 1-year follow-up was significantly more common for African-Caribbeans than for the other two groups. The proportion of African-Caribbeans with a poor outcome was two and a half times greater than that of Whites. On a range of seven socio-demographic variables, African-Caribbeans differed from the other two groups only on unemployment. CONCLUSIONS: A multitide of factors play a role in the aetiology of schizophrenia. Comparison of environmental factors in these groups may identify factors that contribute to the aetiology of schizophrenia.

Adolescent↗
PubMed1997

Increased rate of psychosis among African-Caribbeans in Britain is not due to an excess of pregnancy and birth complications.

BACKGROUND: It has been suggested that the increased rate of psychotic illness among African-Caribbeans living in Britain is due to an excess of pregnancy and birth complications (PBCs). METHOD: We therefore compared the frequency of PBCs in a group of White psychotic patients (n = 103) and a comparable group of patients of African-Caribbean origin (n = 61); the latter consisted of 30 first-generation (born in the Caribbean) and 31 second-generation (born in Britain) individuals. RESULTS: White psychotic patients were more than twice as likely to have a history of PBCs as their African-Caribbean counterparts (odds ratio = 2.34, 95% confidence interval (CI) 0.88-6.47, P = 0.062). The same trend was observed among patients with a DSM-III diagnosis of schizophrenia (odds ratio = 1.65, 95% CI 0.56-4.97, P = 0.32). The rate of PBCs was similar among the first- and second-generation Caribbean psychotic patients. CONCLUSIONS: The increased rate of psychotic illness that has been reported among the African-Caribbean population in Britain is not due to an increased prevalence of PBCs.

Adult↗
PubMed1996

Management of thyroid carcinoma with radioactive 131I.

PURPOSE: To evaluate the role of radioactive 131I in the management of patients with well differentiated carcinoma of the thyroid. METHODS AND MATERIALS: Between 1965 and 1995, a total of 117 patients with well-differentiated carcinoma of the thyroid underwent either lobectomy or thyroidectomy followed by 100-150 mCi of 131I. RESULTS: With a median follow-up of 8 years, only four patients (3%) developed a recurrence of their disease. The 5-year actuarial survival was 97% with a 10-year survival of 91%. There were no severe side effects noted after 131I therapy. CONCLUSIONS: Radioactive 131I is a safe and effective procedure for the majority of patients with well-differentiated thyroid carcinoma. We currently recommend that all patients undergo a subtotal or total thyroidectomy followed by 131I thyroid scanning approximately 4 weeks after surgery. If the thyroid scan shows no residual uptake and all disease is confined to the thyroid, we recommend following patients with annual thyroid scans and serum thyroglobulin levels. If there is any residual uptake detected in the neck or if the tumor extends beyond the thyroid, we recommend routine thyroid ablation of 100-150 mCi of radioactive 131I.

Adolescent↗
PubMed1996

First-contact incidence rates of schizophrenia in Trinidad and one-year follow-up.

BACKGROUND: Incidence rates of schizophrenia among UK African-Caribbeans have been reported as high. Various explanations including selective migration and genetic vulnerability have been proposed. METHOD: In one calendar year, all new cases of psychosis presenting to various psychiatric services in two clearly defined geographical catchment areas in Trinidad-one in the rural south and the other an urban area-were studied. Standardised diagnostic instruments were applied and information collected using WHO screening and measurement instruments. RESULTS: A total of 56 cases were collected, giving an incidence rate of 2.2/1000 of broad schizophrenia with a rate of 1.6 for S+ schizophrenia. CONCLUSION: These rates are similar to those from the WHO study in Honolulu and Aarhus, and much lower than the rates for African-Caribbeans in London. The cases were followed up for one year and the poor outcome rate for schizophrenia was 19%. The findings are discussed in a cross-cultural context and suggestions for future research made.

Adult↗