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Biomedical subjects

B J Bain

Publications and source records attributed to B J Bain.

At least 37 records · Page 2Linked to original sources
PubMed2001

Evaluation of a new screening test for sickle cell haemoglobin.

A new kit for screening for sickle cell haemoglobin (haemoglobin S) has been evaluated. The kit is based on the principle that cells containing haemoglobin S, which have been induced to sickle by exposure to a reducing agent in a phosphate buffer, do not pass through a gel contained in microtubules. In theory, they can thus be distinguished from cells that do not contain haemoglobin S. In practice, the kit was found to be insensitive and unreliable for the detection of haemoglobin S. Homozygosity and heterozygosity for haemoglobin S could not be reliably distinguished. Similarly, patients with haemoglobin S who had been transfused could not be distinguished reliably from those who had not been transfused. In conclusion, unless improved performance can be demonstrated, use of this kit cannot be recommended.

Anemia, Sickle Cell↗
PubMed2001

Overview. Cytogenetic analysis in haematology.

Cytogenetic analysis has contributed greatly to our understanding of the nature of leukaemia and lymphoma. Study of these two groups of diseases has revealed general truths about the nature of the neoplastic process. Cytogenetic analysis has demonstrated that haematological neoplasms result from a somatic mutation occurring in a haemopoietic, lymphoid or multipotent stem cell. Complete remission has been related to disappearance of the clone of cells bearing the mutation whereas the occurrence of clonal evolution has often been found to be indicative of increasingly aggressive disease. Cytogenetic analysis of leukaemias and lymphomas has led to the discovery of numerous proto-oncogenes; these generally play a crucial role in proliferation and differentiation of normal cells with a perturbation of their function leading to neoplasia. In addition, cytogenetic evidence has suggested a role for loss of function of cancer-suppressing genes in haematological neoplasms. Cytogenetic analysis has also made major contributions to precise diagnosis and to the assigning of prognosis and, furthermore, by identifying good and poor prognostic groups has improved the management of patients. Good-prognosis patients have been spared unnecessary treatment and, conversely, more intensive treatment for some diseases associated with a cytogenetic abnormality that was previously indicative of a poor prognosis has improved the outcome for these patients.

Chromosome Aberrations↗
PubMed2001

Bone marrow trephine biopsy.

Trephine biopsies of the bone marrow should be carried out, when clinically indicated, by trained individuals following a standard operating procedure. A bone marrow aspiration should be performed as part of the same procedure. For patient safety and convenience, biopsies are usually performed on the posterior iliac crest. The biopsy specimen should measure at least 1.6 cm and, if it does not, consideration should be given to repeating the procedure, possibly on the contralateral iliac crest. If bone marrow aspiration is found to be impossible, imprints from the biopsy specimen should be obtained. Otherwise, the specimen is placed immediately into fixative and after fixation is embedded in a resin or, more usually, decalcified and embedded in paraffin wax. Thin sections are cut and are stained, as a minimum, with haematoxylin and eosin and with a reticulin stain. A Giemsa stain is also desirable. A Perls' stain does not often give useful information and is not essential in every patient. The need for other histochemical or immunohistochemical stains is determined by the clinical circumstances and the preliminary findings. Trephine biopsy sections should be examined and reported in a systematic manner, assessment being made of the bones, the vessels and stroma, and the haemopoietic and any lymphoid or other tissue. Assessment should begin with a very low power objective, the entire section being examined. Further examination is then done with an intermediate and high power objective. Ideally, reporting of trephine biopsy sections should be done by an individual who is competent in both histopathology and haematology, and who is able to make an appropriate assessment of both the bone marrow aspirate and the trephine biopsy sections. When this is not possible, there should be close consultation between a haematologist and a histopathologist. The report should both describe the histological findings and give an interpretation of their importance. A signed or computer authorised report should be issued in a timely manner. If the report is a preliminary, this must be clearly stated.

Biopsy↗
PubMed2001

Bone marrow aspiration.

Bone marrow aspiration biopsies are carried out principally to permit cytological assessment but also for immunophenotypic, cytogenetic, molecular genetic, and other specialised investigations. Often, a trephine biopsy is carried out as part of the same procedure. Bone marrow aspirations should be carried out by trained individuals who are aware of the indications, contraindications, and hazards of the procedure. They should follow a standard operating procedure. The operator should have made an adequate assessment of clinical and haematological features to ensure both that appropriate indications exist and that all relevant tests are performed. For the patient's comfort and safety, the posterior iliac crest is generally the preferred site of aspiration. Films of aspirated marrow and, when appropriate, films of crushed particles should be made and labelled. Once thoroughly dry, films should be fixed and stained. As a minimum, a Romanowsky stain and a Perls' stain are required. A cover slip should be applied. The bone marrow films should be assessed and reported in a systematic manner so that nothing of importance is overlooked, using a low power, then intermediate, then high power objective. A differential count should be performed. An interpretation of the findings, in the light of the clinical and haematological features, should be given. The report should be signed or computer authorised, using a secure password, and issued in a timely manner.

Biopsy, Needle↗
PubMed2001

Investigation of ethnic neutropenia by assessment of bone marrow colony-forming cells.

Healthy individuals with African ancestry have lower neutrophil counts than Caucasians. It has previously been postulated that this was consequent on either a diminished bone marrow granulocyte reserve or an altered distribution of neutrophils between the circulating and marginated granulocyte pools. Recent indirect evidence supports the former hypothesis. In this study we have compared the number of granulocyte plus granulocyte-macrophage colony-forming units (CFUs) in the bone marrow of healthy African and Afro-Caribbean subjects with the number of CFUs in the bone marrow of healthy age and sex-matched Caucasians. We found the group with African ancestry to have significantly fewer CFUs than the Caucasian group. There was no evidence of any qualitative difference between the CFUs of the two ethnic groups: they showed similar sensitivity to granulocyte-monocyte colony stimulating factor and similar enhancement of growth when cultured with a larger range of cytokines. These observations suggest that ethnic neutropenia observed in those with African ancestry is likely to result from reduced numbers of bone marrow progenitor cells in comparison with numbers present in Caucasians.

Adolescent↗
PubMed2000

Neutrophil dysplasia caused by mycophenolate mofetil.

Two transplant recipients developed striking morphological abnormalities in their circulating neutrophils while receiving mycophenolate. The changes included nuclear hypolobulation and abnormal clumping of nuclear chromatin and were presumably related to inhibition of guanosine nucleoside synthesis. In both cases the neutrophil abnormalities preceded the development of neutropenia and were thus a sign of impending hematological toxicity. The hematological changes resolved after the drug was discontinued.

Adult↗
PubMed2000

Investigation of the effect of marathon running on leucocyte counts of subjects of different ethnic origins: relevance to the aetiology of ethnic neutropenia.

Healthy subjects of African ancestry, including Afro-Caribbeans, have been observed to have lower total white cell counts and neutrophil counts than healthy Caucasian subjects. The cause of this ethnic neutropenia is unclear. We have previously found no evidence that increased margination of neutrophils is responsible. In this study, we have investigated mobilization of neutrophils from the bone marrow granulocyte reserve by endurance exercise. We investigated subjects of different ethnic origins before and after they had competed in a marathon race. Before the race, the neutrophil counts of Africans/Afro-Caribbeans were significantly lower than those of Caucasians (means 2.49 and 3.21 x 109/l respectively; P = 0.043). After the race, the difference was greater, as was the degree of significance (means 10.21 and 12.33 respectively; P = 0.017). The percentage increment was almost identical whereas the absolute increment was considerably less, although of marginal statistical significance (increment 7.72 and 9. 12 x 109/l respectively; P = 0.10). Similar changes were observed in the monocyte count. Before the race, the difference in the means was of marginal statistical significance (0.35 and 0.41 x 109/l respectively; P = 0.105), whereas after the race the difference was greater and was highly significant (means 0.75 and 1.05 x 109/l respectively; P = 0.001). These observations support the results of our earlier study, both of which suggested that ethnic neutropenia is likely to result from a diminished bone marrow reserve rather than being consequent on altered distribution of neutrophils within the blood stream.

Adult↗
PubMed2000

Hypereosinophilia.

Recent advances in our understanding of hypereosinophilia have related particularly to the definition of criteria for distinguishing between eosinophilic leukemia and the 'idiopathic' hypereosinophilic syndromes. In this article, leukemogenic mechanisms have been identified in a number of subtypes of eosinophilic leukemia, and the role of clones of T lymphocytes in the causation of otherwise unexplained eosinophilia has been further elucidated. The roles of various therapeutic modalities-including cytotoxic chemotherapy, interferon and bone marrow transplantation-in eosinophilic leukemia and in the idiopathic hypereosinophilic syndrome also have been further defined.

Clone Cells↗
PubMed2000

Exercise induced mobilisation of the marginated granulocyte pool in the investigation of ethnic neutropenia.

This study was designed to determine whether ethnic neutropenia is caused by an increased proportion of neutrophils being present in the marginated granulocyte pool. Thirty two healthy volunteers, half of whom were African or Afro-Caribbean and half of whom were white, exercised vigorously for 10 minutes on a step machine to mobilise granulocytes from the marginated granulocyte pool into the circulating granulocyte pool. The amount of work performed and the pulse rate response of the two ethnic groups were compared to determine whether the exercise carried out was comparable. A full blood count and an automated differential count were performed before and after the exercise. The haemoglobin concentration, platelet count, and absolute counts of total leucocytes and leucocyte subsets before and after exercise were compared in each individual and the values in the two ethnic groups both before and after exercise were compared. The absolute increase in neutrophils in the two ethnic groups was compared. The African/Afro-Caribbean group was found to have a reduced rather than enhanced ability to mobilise neutrophils from the marginated granulocyte pool. Therefore, increased margination of neutrophils is unlikely to be the cause of ethnic neutropenia.

Adolescent↗
PubMed1999

Prospective study of HTLV-I infection in an initially asymptomatic cohort.

A prospective clinical study of 20 initially asymptomatic HTLV-I-seropositive carriers was commenced in 1991 to determine the natural history of the infection in relation to HTLV-I proviral load, immune responses, and lymphocyte phenotype. Proviral load varied widely between carriers but was relatively constant within an individual over time. The lymphocyte phenotype and prevalence of activated lymphocytes were not predictive of disease and the magnitude of the cytotoxic T-lymphocyte response to HTLV-I was independent of proviral load. Incident conditions, some related to HTLV-I infection, including a case of HTLV-I-associated myelopathy (HAM), were documented in 9 carriers. Development of myelopathy and uveitis was associated with high peripheral blood HTLV-I proviral load that predated symptoms. Persistently high proviral load appears to predate the development of HTLV-I-associated inflammation in neuro-ophthalmic tissue.

Adult↗
PubMed1999

Artefactual elevation of an automated white cell count following femoral vein puncture.

We report the novel occurrence of an erroneous automated total and differential white blood cell count on a blood sample obtained by traumatic femoral venepuncture, caused by contamination of the blood sample with subcutaneous adipose tissue. The erroneous counts were observed on a Bayer-Technicon H2 analyser while counts on a Coulter GenS, were much less affected. Characteristic scatter plots from both instruments are illustrated.

Aged↗