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Biomedical subjects

R J Lock

Publications and source records attributed to R J Lock.

At least 19 recordsLinked to original sources
PubMed2005

Flow cytometric characterisation of cells of differing densities isolated from human term placentae and enrichment of villous trophoblast cells.

Cells were isolated from human term placentae by trypsinisation of fragments of chorionic villi and fractionation of cells on a Percoll density gradient into six layers. A panel of 10 monoclonal antibodies to antigens on or in trophoblast cells (placental alkaline phosphatase (PLAP), cytokeratin-7, beta-human chorionic gonadotrophin (beta-hCG), human leucocyte antigen-G (HLA-G)), leucocytes (CD45), monocytes, macrophages, dendritic cells, B cells (HLA class II), mesenchyme cells (vimentin), fibroblasts (fibroblast antigen) and nucleated cells excluding villous trophoblast (HLA class I, CD9) was used to characterise the cells by flow cytometry. For staining intracellular antigens (cytokeratin, vimentin, beta-hCG) the cells were first fixed and permeabilised. The upper two layers from the gradient (density 1.013-1.039 g/ml) contained predominantly PLAP-positive cells or fragments, probably derived from the syncytiotrophoblast. Cytokeratin-positive cells accumulated mainly in the layer of density 1.039-1.052 g/ml and comprised the majority of the cell types identified in this fraction. Few or no cells reactive with antibodies to beta-hCG or HLA-G were identified in any layer. Non-trophoblast cells were heavier, being present mainly at densities 1.052-1.079 g/ml (CD45, HLA class I, vimentin) and 1.066-1.092 g/ml (fibroblast). Fewer than 10% of cells in any layer were HLA class II- or CD9-positive. Further purification of trophoblast cells was by negative immunomagnetic separation with removal of CD45-positive cells and HLA class II-positive cells to less than 1%. On culture of the cells from each layer, those of density 1.039-1.066 g/ml exhibited characteristics of cytotrophoblast cells; they secreted high levels of human chorionic gonadotrophin and formed adherent multinucleate cells. This procedure enabled the selection and enrichment of cytotrophoblast cells and/or syncytiotrophoblast fragments that are suitable for cellular and molecular studies.

Cell Count↗
PubMed2005

C1 inhibitor deficiency: diagnosis.

This is the first of two articles on C1 inhibitor deficiency based on a recent UK consensus document covering diagnosis and management of the disorder in both adults and children. This paper focuses on diagnosis of this disorder.

Abdominal Pain↗
PubMed2005

C1 inhibitor deficiency: consensus document.

We present a consensus document on the diagnosis and management of C1 inhibitor deficiency, a syndrome characterized clinically by recurrent episodes of angio-oedema. In hereditary angio-oedema, a rare autosomal dominant condition, C1 inhibitor function is reduced due to impaired transcription or production of non-functional protein. The diagnosis is confirmed by the presence of a low serum C4 and absent or greatly reduced C1 inhibitor level or function. The condition can cause fatal laryngeal oedema and features indistinguishable from gastrointestinal tract obstruction. Attacks can be precipitated by trauma, infection and other stimulants. Treatment is graded according to response and the clinical site of swelling. Acute treatment for severe attack is by infusion of C1 inhibitor concentrate and for minor attack attenuated androgens and/or tranexamic acid. Prophylactic treatment is by attenuated androgens and/or tranexamic acid. There are a number of new products in trial, including genetically engineered C1 esterase inhibitor, kallikrein inhibitor and bradykinin B2 receptor antagonist. Individual sections provide special advice with respect to diagnosis, management (prophylaxis and emergency care), special situations (childhood, pregnancy, contraception, travel and dental care) and service specification.

Adolescent↗
PubMed2004

Rapid diagnosis and characterization of acute promyelocytic leukaemia in routine laboratory practice.

The rapid diagnosis of the t(15;17)(q22;q21) promyelocytic leukaemia is important in the early introduction of targeted therapy with all-trans retinoic acid plus chemotherapy. It has been noted that these are usually myeloperoxidase (MPO)-positive and HLA-DR-negative with homogenous expression of CD33 and heterogeneous expression of CD13. We evaluated the use of immunophenotyping, morphology and cytogenetics in our own practice. Cascade testing, using cytoplasmic MPO expression in a high percentage of blast cells in bone marrow as the primary screen and PML (promyelocytic leukaemia protein) expression as the secondary confirmatory test, allowed rapid identification of the cases with t(15;17). This approach allows early instigation of appropriate therapy.

Adult↗
PubMed2004

Acquired C1 esterase inhibitor deficiency or serendipity? The chance finding of a paraprotein after an apparently low C1 esterase inhibitor concentration.

Acquired C1 esterase inhibitor deficiency is a rare condition, usually presenting after the 2nd decade of life, and is often related to underlying conditions such as autoimmune and lymphoproliferative disorders. This case report describes a man whose initial clinical presentation with acute angioedema and whose initial estimation of a low C1 esterase inhibitor concentration indicated that he had an acquired angioedema, possibly secondary to a B cell neoplasm. A paraprotein was detected, and although its detection was serendipitous because it hinged on a spurious C1 esterase inhibitor result, this case confirms the role of C4 concentrations in the investigation of C1 esterase inhibitor deficiency. It also confirms the need to obtain repeat confirmatory samples before arriving at a diagnosis, however convincing the clinical signs may be.

Acute Disease↗
PubMed2004

Echocardiographic abnormalities in primary antibody deficiency.

OBJECTIVE: To document cardiac abnormalities secondary to pulmonary disease in primary antibody deficiency. PATIENTS AND METHODS: A cross sectional audit study of patients from a regional immunology centre. Subjects undergoing two dimensional and Doppler transthoracic echocardiography were reviewed. Ventricular dimensions and function, valvular competence, and estimated pulmonary artery pressure were recorded. Data were compared with clinical variables, pulmonary function tests, and thoracic computed tomography data. RESULTS: Nineteen patients with common variable immunodeficiency and one with IgG(2) subclass deficiency were included, mean age at diagnosis 37.5 years, mean estimated diagnostic delay 10.94 years. Left ventricular impairment was found in 15% and right heart dilatation in 20%. Pulmonary hypertension (mean pulmonary artery pressure >25 mm Hg) was found in 45% (9/20), graded as moderate (40-60 mm Hg) in 44% of cases. Pulmonary function was obstructive in 47% (9/19). Fifty five percent of the patients with computed tomography data within the last five years (10/18) had confirmed bronchiectasis. Patients with right heart dilatation and/or moderate pulmonary hypertension (n = 6) had a more prolonged diagnostic delay (p = 0.04) and more severe lung disease. CONCLUSION: Echocardiographic abnormalities are common in primary antibody deficiency, associated with diagnostic delay and pulmonary complications. Pulmonary hypertension should be considered in those with severe lung disease and can be confirmed by echocardiography.

Adult↗
PubMed2004

Subclinical hypothyroidism: a comparison of strategies to achieve adherence to treatment guidelines.

BACKGROUND: Subclinical hypothyroidism is an entity based on the laboratory findings of a raised serum thyrotrophin (TSH) concentration and a normal free thyroxine (FT(4)) concentration. Patients with subclinical hypothyroidism who also have anti-thyroid peroxidase (TPO) antibodies have a higher conversion to overt hypothyroidism than those without, and treatment with thyroxine is recommended. METHOD: We audited anti-TPO assay requests within two NHS Trust hospitals, against consensus standards, to ascertain whether a cascade approach to anti-TPO testing and direct advice leads to more appropriate prescribing of thyroxine in general practice. RESULTS: Our data show that where anti-TPO status was automatically tested for and clear advice for treatment given, >85% of patients were treated according to the standard required by the consensus document, with >90% of those recommended to be commenced on thyroxine actually doing so. In contrast, where anti-TPO was not routinely assessed, treatment was started in 46% of patients, without clear evidence that this was appropriate. CONCLUSION: In order to better advise clinicians and in accordance with the agreed protocol, laboratory-generated cascade testing for anti-TPO antibodies should be an integral part of the investigation of subclinical hypothyroidism, and reports should contain appropriate interpretation and advice.

Antibodies↗
PubMed2003

Misdiagnosis of hereditary angio-oedema type 1 and type 2.

BACKGROUND: Hereditary angio-oedema is a rare, life-threatening, autosomal dominant condition caused by deficiency (type 1) or dysfunction (type 2) of complement C1 inhibitor. Serological assays to measure C1 inhibitor concentration and function are widely available. However, expert interpretation may not be. OBJECTIVE: To review all cases within three NHS Trusts with a putative diagnosis of hereditary angio-oedema. METHOD: Review of laboratory results and clinical notes of 44 cases of presumed hereditary angio-oedema. RESULTS: Audit revealed that 11 of 42 (26%) cases had been incorrectly considered to have a diagnosis of hereditary angio-oedema. Two of 44 had insufficient data to assess. All 11 had low functional C1 inhibitor recorded at presentation. RESULTS: available in these 11 cases at the time of diagnosis showed a normal or borderline C4 level (>or= 50% of mean normal, in contrast to hereditary angio-oedema, where C4 was less than 40% of mean normal) indicating that the low C1 inhibitor levels were a result of sample decay. Cases incorrectly diagnosed were predominantly female and had a mean age at presentation of 40 years (compared with 22 years for type 1 hereditary angio-oedema). Six of the 11 cases were offered C1 inhibitor concentrate (pooled plasma product) as treatment. CONCLUSION: We recommend that all suspected cases of hereditary angio-oedema are reviewed, that specialist advice is sought before making the diagnosis and that the diagnosis is only made after initial abnormal serology is confirmed on a second sample.

Adolescent↗
PubMed2003

Lymphoproliferative disease in antibody deficiency: a multi-centre study.

We have undertaken a retrospective study of antibody deficient patients, with and without lymphoma, and assessed the ability of specific polymerase chain reaction (PCR) primers to determine if the detection of clonal lymphocyte populations correlates with clinical and immunohistochemical diagnosis of lymphoma. We identified 158 cases with antibody deficiency presenting during the past 20 years. Paraffin-embedded biopsy specimens or slides were available for analysis in a cohort of 34 patients. Of these patients, 29 had common variable immunodeficiency, one X-linked agammaglobulinaemia, one X-linked immunoglobulin deficiency of uncertain cause and three isolated IgG subclass deficiency. We have confirmed that lymphoma in antibody deficiency is predominantly B cell in origin. Clonal lymphocyte populations were demonstrated in biopsies irrespective of histology (16/19 with lymphoma and 11/15 without). Isolated evidence of clonality in biopsy material is therefore an insufficient diagnostic criterion to determine malignancy. Furthermore, our data suggest that clonal expansions are rarely the result of Epstein-Barr virus-driven disease.

Adult↗
PubMed2003

Immunoglobulins and immunoglobulin subclasses in the elderly.

BACKGROUND: Published data imply that adult concentrations are achieved for all Ig isotypes and plateau by 15-18 years of age. Recent data, however, suggest that these results are not applicable in the elderly. There are no equivalent data for IgG subclasses. We present reference range data for an elderly UK patient population, for IgG, IgA, IgM and IgG subclasses. METHODS: Serum immunoglobulins were reviewed on samples from 1146 patients > 60 years of age and 925 patients aged 18-60 years. Serum IgG subclasses were reviewed on samples from 498 patients >60 years and 484 patients aged 18-60 years. All Igs and subclasses were measured by nephelometry. Reference ranges were derived by probability plotting. RESULTS: Serum median IgG and IgM concentrations are reduced in the elderly (IgG female P < 0.001, IgG male P < 0.03; IgM female P < 0.001, IgM male P < 0.001). Serum IgA concentrations are maintained. Indeed, men showed a slight increase in serum IgA with age (P = 0.03). Few differences dependent on gender were seen. Median IgM was lower in men in the younger age groups (18-60 years P < 0.001; 61-70 years P = 0.017). IgG(2) is reduced in elderly men (P = 0.002) and IgG, reduced in elderly women (P = 0.009). CONCLUSIONS: We advocate that centres offering these investigations provide local, method-dependent reference ranges, and suggest an approach as to how this might be achieved.

Adolescent↗
PubMed2002

A multicentre evaluation of the diagnostic efficiency of serological investigations for C1 inhibitor deficiency.

AIM: To determine the diagnostic efficiency of assays routinely used in the investigation of hereditary angio-oedema. METHODS: Over a four year period, 1144 samples were received for analysis from 907 patients suspected of C1 inhibitor deficiency. Analyses were performed for C4 and C1 inhibitor (functional and immunochemical). Notes were reviewed retrospectively on patients with low serological indicators to determine diagnosis. RESULTS: These are the first data to indicate the sensitivity, specificity, and predictive values of the assays most frequently used to screen for C1 inhibitor deficiency. A combination of low C4 and low C1 inhibitor function has 98% specificity for C1 inhibitor deficiency in this population and a 96% negative predictive value, and is thus a very effective screen. All patients with untreated C1 inhibitor deficiency had a low C4 value. CONCLUSIONS: All patients considered for a diagnosis of C1 inhibitor deficiency should have serum examined to measure both C4 and functional C1 inhibitor. If either is normal at presentation this essentially excludes a diagnosis of C1 inhibitor deficiency. These tests can be performed sequentially. If C4 is normal it is not necessary to proceed to C1 inhibitor analysis. If C1 inhibitor function and C4 are both low then a repeat sample should be obtained to confirm the findings.

Angioedema↗
PubMed2002

Takayasu arteritis: a review.

Takayasu arteritis is a well known yet rare form of large vessel vasculitis. This review details the history, clinical features, differential diagnoses, classification, and immunology of the disorder. Suppression of inflammation and preservation of vascular competence are the aims of treatment. As with any rare disease, randomised controlled treatment trials are either lacking or based on small patient numbers, making management decisions difficult. Current evidence based treatments are presented and discussed.

Diagnosis, Differential↗
PubMed2002

Dermatitis herpetiformis and neurological dysfunction.

Dermatitis herpetiformis and coeliac disease are gluten sensitive diseases, which have common immunopathological and genetic mechanisms. Neuropsychiatric complications have been reported in up to 26% of patients with coeliac disease. This is probably an overestimate, because of the chance associations with some common neurological conditions such as epilepsy. The pathogenesis is speculative but it has been postulated that gluten is neurotoxic possibly via immune mechanisms. The frequency of neurological dysfunction in patients with dermatitis herpetiformis has not been characterised. Patients with dermatitis herpetiformis might be expected to be particularly susceptible to neuronal damage as some continue to consume gluten when their dermatological symptoms are controlled by dapsone. Thirty five patients were recruited with dermatitis herpetiformis from dermatology clinics at St Mary's Hospital, London and Queen's Medical Centre, Nottingham and investigated for evidence of neurological abnormality. All patients underwent a full neurological examination and were asked about their neurological and general medical history by means of a structured questionnaire. Serum samples were taken and screened for the presence of anti-neuronal antibodies (anti-Hu and Yo) as well as anti-gliadin (IgA and G) anti-endomysial (IgA), and anti-tissue transglutaminase (IgA) antibodies. Neurophysiological tests were carried out where appropriate. Only two patients were identified with unexplained neurological abnormalities (one essential tremor, and one chorea). Two other patients had a history of migraine. The patient with chorea also had borderline/equivocally positive anti-Hu antibodies by immunofluorescence assay. All other samples were negative for anti-neuronal antibodies. Fifteen patients were positive for anti-gliadin antibodies (IgA and/or IgG), four for anti-endomysial antibodies (monkey oesophagus or umbilical cord), and six for anti-tissue transglutaminase antibodies. The presence of these antibodies did not correlate with the presence of neurological abnormalities. No cases of "gluten ataxia" were identified. In conclusion, there was no convincing evidence for immune mediated neurological damage in this pilot study of dermatitis herpetiformis.

Adolescent↗
PubMed2001

Antibodies to extractable nuclear antigens. Has technological drift affected clinical interpretation?

Precipitating antibodies to extractable nuclear antigens are important in the diagnosis of connective tissue diseases. Disease associations are defined using gel based techniques. Alternative technologies have been introduced, including passive haemagglutination, enzyme linked immunosorbent assay, and western blotting. This leader contains a review of the literature on the clinical usefulness of these assays, together with knowledge gained from personal experience. Using the example of systemic lupus erythematosus, the sensitivity, specificity, and positive predictive value of the assays for disease is discussed, as is their differences in performance. The conclusion drawn is that disease specificity is method dependent. Validation and audit of performance of the method selected by the investigation laboratory is essential.

Antibodies, Antinuclear↗
PubMed2001

The high prevalence of autoantibodies to tissue transglutaminase in first-degree relatives of patients with type 1 diabetes is not associated with islet autoimmunity.

OBJECTIVE: To determine the extent of celiac autoimmunity in type 1 diabetic patients and the overlap between islet and celiac autoimmunity in their nondiabetic relatives. RESEARCH DESIGN AND METHODS: IgA antibodies to tissue transglutaminase were determined in serum taken from 433 type 1 diabetic patients and 1,442 nondiabetic first-degree relatives. Samples with transglutaminase antibodies above the 97.5th percentile of 347 schoolchildren were also assayed for IgA anti-endomysial antibodies (EMAs). Markers of islet autoimmunity (islet cell antibodies and autoantibodies to insulin, glutamate decarboxylase. and protein tyrosine phosphatase IA-2) had previously been measured in all relatives. RESULTS: In the absence of known celiac disease, the prevalence of transglutaminase antibody levels above the 97.5th percentile of the schoolchildren was 13.4% in diabetic patients and 7.0% in nondiabetic relatives. ENMAs were found in addition to transglutaminase antibodies in 2.6% of probands and in 1.9% of first-degree relatives, but none of the schoolchildren. Transglutaminase antibodies were found to persist in 10 of 30 patients and in 30 of 59 relatives with follow-up samples taken at least 2 years after the initial sample. Of 186 nondiabetic relatives with islet autoantibodies, only 10 also had transglutaminase antibodies. CONCLUSIONS: We found a high prevalence of celiac autoimmunity in patients and first-degree relatives of children with type 1 diabetes, but we found limited overlap between islet and celiac autoimmunity in nondiabetic relatives. The high prevalence of celiac autoimmunity may be explained by shared genetic susceptibility and identifies a population within which screening for the disease may be justified.

Adolescent↗
PubMed2001

Coeliac disease, anaemia and pregnancy.

We have investigated the prevalence of positive serology for coeliac disease in pregnant women, using the IgA anti-endomysium antibody test. Five of 216 pregnant women with a haemoglobin less than 11 g/dl were positive, compared to 0/350 with haemoglobin > or = 11 g/dl. Four of these five had low plasma ferritin levels, indicative of iron deficiency anaemia; the fifth was borderline normal. We found no association between positive coeliac disease serology and folate deficiency. None of thirty mothers of children born with neural tube defects were IgA anti-endomysium antibody positive. This study has identified a very high prevalence of occult coeliac disease in pregnancy and a strong association with anaemia. We advise that in cases with a haemoglobin of less than 11 g/dl in pregnancy, coeliac disease should be excluded.

Adolescent↗