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Biomedical subjects

B Bain

Publications and source records attributed to B Bain.

At least 37 records · Page 2Linked to original sources
PubMed1995

Complex hypodiploidy in acute myeloid leukaemia: a United Kingdom Cancer Cytogenetics Group study.

Forty cases of acute myeloid leukaemia with 41 hypodiploid clones were investigated in a collaborative study. Cases with -5, -7, -X or -Y either alone or in association with an established translocation were excluded. Karyotypes were reviewed in all cases and bone marrow or blood morphology was reviewed in 22 cases. Twenty-six cases were very complex (more than five abnormal chromosomes), 14 cases were complex (two to five abnormal chromosomes) and only one case was simple (one abnormal chromosome). Chromosomes 5, 7, 17 and 18 were involved in a significantly greater number of cases than expected. Only five cases had normal chromosomes 5 and 7. Chromosomes 10, X and Y were involved in significantly fewer cases than expected. Ten cases had ring chromosomes and 18 showed clonal evolution. Patients were aged between 19 and 90, median 61 years. Evidence of myelodysplasia was found on morphological review in 18/22 cases, and on clinical features in a further five cases. There was a high proportion of cases with FAB M6, 'erythroleukaemia' (9/31 cases). Only 4/16 patients treated with cytotoxic therapy achieved remission. Median survival was 2.5 months (35 patients). Survival was slightly better for patients with normal chromosomes 5 and 7, and for those with simpler karyotypes, but this was not statistically significant. This study confirms the association between hypodiploidy, complex karyotype, abnormalities of chromosomes 5 and 7 and a poor prognosis.

Adult↗
PubMed1995

Abnormalities of 3q21 and 3q26 in myeloid malignancy: a United Kingdom Cancer Cytogenetic Group study.

Cytogenetic and clinical details are presented for 66 patients with myeloid malignancy and chromosome abnormalities of 3q21 and/or 3q26 (3qabns). Bone marrow and/or peripheral blood morphology was assessed for 52 cases. 3qabns in Philadelphia negative (Ph-ve) and positive (Ph+ve) cases were inv(3)(q21q26), (21 Ph-ve, 6 Ph+ve); t(3;3)(q21;q26) (nine Ph-ve, four Ph+ve); and t(3;21)(q26;q22) (four Ph-ve, six Ph+ve). Ph-ve cases also had t(1;3)(p36;q21) (three cases), and t(3;5)(q21;q31)/(q21;q35)/(q26;q21) (five cases aged < 40 years). Three cases, aged < 30 years, had t(3;12)(q26;p13) which defines a new 3qabn subgroup. Monosomy 7 and/or 5q- accompanied inv(3) or t(3;3) in 17/30 cases. All cases had a myeloid malignancy (predominantly AML M1, M4 or M7), frequent trilineage myelodysplasia, and markedly abnormal megakaryopoiesis with micromegakaryocytes (< 30 microns). Thrombocytosis occurred in two cases only. Most Ph+ve cases were in myeloid blast crisis and in Ph+ve cases alone, micro-megakaryocytes were uniquely small (10 microns) in 7/11 cases. There were equal numbers of males and females. Seven secondary leukaemias were found in Ph-ve cases with inv(3), t(3;3), t(3;21), t(1;3) or del(3)(q21). Three cases with t(3;21) (one Ph+ve) were de novo AML or had de novo aplastic anaemia. Survival was rarely greater than 12 months from detection of the 3qabn.

Adolescent↗
PubMed1995

Screening criteria for beta thalassaemia trait in pregnant women.

AIMS: To establish suitable screening criteria for beta thalassaemia trait during pregnancy using an automated blood counter incorporating light scattering technology. METHODS: Pregnant women (n = 857) at a London antenatal clinic were investigated for beta thalassaemia trait if the Technicon H.2 full blood count showed either a mean corpuscular volume (MCV) < 85 fl or a mean corpuscular haemoglobin (MCH) < 27 pg. Results were then analysed to establish which of these variables was more suitable for screening and to determine suitable cut off points for calculating the haemoglobin A2 percentage. RESULTS: The MCH was superior to the MCV for thalassaemia screening as it was a more stable measurement and fewer unnecessary tests were performed. A MCH less than 27 pg is a suitable cut off point for screening. This screening criterion was equally applicable to a Coulter impedance counter. CONCLUSIONS: Pregnant women presenting at an antenatal clinic with a MCH < 27 pg should be investigated further to confirm or exclude a diagnosis of beta thalassaemia trait.

Erythrocyte Indices↗
PubMed1995

Is there central fatigue during simulated air combat maneuvering?

This study tested the hypothesis that repeated exposure to high levels of +Gz acceleration, in conjunction with repeated execution of an Anti-G Straining Maneuver (AGSM), causes central fatigue, presumably by impairing central nervous system (CNS) function. We speculated that central fatigue would impair the ability to recruit sufficient musculature at the intensity required to perform an adequate anti-G straining maneuver. Central fatigue was evaluated by measuring maximal force generation and surface electromyographic activity of leg extensor muscles before, during, and immediately upon termination of an SACM, and comparing these values to those obtained when the muscles were electrically stimulated during maximal voluntary contractions (MVCs). We assumed that any observed increase in force generation during the MVCs, caused by the stimulation, would indicate central fatigue. G-tolerance time was 230 +/- 172 s. Hypoxia was induced by the SACM as the arterial oxygen saturation decreased significantly from 97% to 90%. In spite of this hypoxia, there was no significant change in MVC force when the pre- and post-SACM values were compared. Electrical stimulation during the MVC's did not cause an increase in force generation. The average forces generated during the +7 Gz phase of the SACM were only about 35% of MVC force. This force value did not change significantly during the SACM. The results indicate that the inability to continue to perform the AGSM during an SACM is not likely due to central fatigue or to fatigue of the large skeletal muscle groups we have examined.(ABSTRACT TRUNCATED AT 250 WORDS)

Aerospace Medicine↗
PubMed1994

Electromyographic indices of muscle fatigue during simulated air combat maneuvering.

Pilots exposed to high levels of headward (+Gz) acceleration must perform voluntary muscle contractions in order to maintain head-level arterial pressure. To study the possibility that muscular fatigue can limit human +Gz duration tolerance, electromyographic (EMG) activity and EMG indices of muscular fatigue were measured during a simulated air combat maneuvering (SACM) centrifuge profile. Eight experienced male volunteers were exposed to a +4-7 Gz centrifuge profile until volitional fatigue. Electrical activity (EMG) was recorded from 7 muscles: biceps brachii (BB), latissimus dorsi (LD), pectoralis major (PM), rectus abdominis (RA), vastus lateralis (VL), biceps femoris (BF) and gastrocnemius (GN). EMG and force during isometric contractions of the same muscles were also recorded at 1 G. Root mean square (RMS) and mean power frequency (MPF) were calculated for each second of EMG data. G-tolerance time averaged 256 +/- 33 s (mean +/- SD). RMS activity was expressed relative to activity during a maximal muscle contraction. The mean values (%) for each muscle during the 7 Gz plateaux were: RA, 30.8; BB, 26.4; LD, 44.0; PM, 48.5; VL, 43.4; BF, 31.4; GN, 39.3. The estimated level of contraction relative to a MVC (%) was: RA, 36.6; BB, 30.5; LD, 43.9 and PM, 61.4. There was no significant difference between contraction levels for any of the muscles studied. RMS activity did not increase over time and MPF decreased significantly only in BF and LD, however, these decreases were small. EMG activity and estimated contraction intensities were considered to be low to moderate. These results suggest that it is unlikely that fatigue in the muscles studied would limit G-tolerance time.

Adult↗
PubMed1992

Effect of simulated air combat maneuvering on muscle glycogen and lactate.

Muscle glycogen and muscle and blood lactate were evaluated before and after a +4.0/7.0 Gz simulated air combat maneuvering (SACM) protocol in the human centrifuge. The subjects were eight healthy males, ages 25-43 years. Muscle glycogen and lactate were determined from biopsies of m. vastus lateralis in six subjects and whole blood lactate was analyzed in finger-tip blood samples from eight subjects. G-tolerance time was 256 +/- 33 s (Mean +/- S.E.M.). The decrease in glycogen concentration averaged 81 +/- 36 mmol.kg-1 dry wt (p = 0.07). The rate of glycogen utilization was low, averaging 0.4 +/- 0.1 mmol.kg-1.s-1. Muscle lactate increased significantly from 28 +/- 2 mmol.kg-1 dry wt pre-SACM to 51 +/- 4 mmol.kg-1 post-SACM. Post-SACM blood lactate was 4.2 +/- 0.3 mmol.L-1. Neither final blood nor muscle lactate values nor the difference between pre- and post-SACM muscle lactate concentrations were related to G-tolerance time. It was concluded that glycogen availability in m. vastus lateralis is not a limiting factor during exposure to headward acceleration of this type and duration. The lactate values, while high, cannot fully explain the muscular fatigue occurring during centrifuge exposures of the type used here. Therefore, the suggestion by others that anaerobic energy metabolism in skeletal muscles is the crucial factor limiting the ability to resist fatigue during exposure SACM is not supported and is likely an oversimplification of a much more complex problem.

Adult↗
PubMed1992

Penicillin anaphylaxis: a review of sensitization, treatment, and prevention.

Penicillin and its derivatives are the commonest cause of drug-induced anaphylaxis, accounting for some 500 deaths per year in the United States. Penicillins are, however, sometimes withheld unnecessarily in patients who give spurious histories of penicillin allergy. A properly performed skin test will detect patients at risk of serious anaphylaxis. Many physicians do not fully appreciate the value of penicillin skin testing, however, and this has contributed to the withholding of penicillin and the use of other, often more expensive medications. Skin testing with a mixture of benzylpenicilloyl polylysine (major determinant) and a minor determinant mixture detects all patients at risk of major anaphylaxis. Of patients who test negative with these reagents, 1% to 4% will have non-life-threatening urticarial reactions. Skin testing is most useful in patients with a vague or inconsistent history of penicillin allergy for whom alternative antibiotics would not be effective or convenient. Aztreonam is the only semisynthetic penicillin that may safely be used in penicillin-allergic patients. Desensitization may be attempted in the patient with a positive skin test for whom there is no alternative to a penicillin-type drug.

Anaphylaxis↗
PubMed1992

Limb blood flow while wearing aircrew chemical defense ensembles in the heat with and without auxiliary cooling.

The effect of auxiliary air cooling on endurance time and limb blood flow in the heat (37 degrees C, 50% r.h., target time = 150 min) while wearing aircrew chemical defense (CD) ensembles was examined. Eight males were dressed in aircrew CD ensembles with or without an air-cooled vest. After an initial 10 min treadmill walk and 20 min of seated rest, the subjects alternately rested and exercised on a cycle ergometer (10 min rest, 10 min exercise) resulting in an overall metabolic rate of 240 W. Arm and leg blood flow (ABF, LBF), determined by venous occlusion plethysmography, were significantly lower with air cooling (AC) than with no cooling (NC) during the same time period (p less than 0.05). Endurance time was much greater with AC than with NC (150 min AC vs. 92 +/- 0.08 min NC, p less than 0.01). Arm and calf skin temperatures, rectal temperature and heart rate were all significantly lower with AC than with NC (p less than 0.05) after the onset of the cycle exercise. The results show that the use of the air-cooled vest under these conditions was able to increase heat tolerance and reduce blood flow to the periphery.

Adult↗
PubMed1991

Leukaemia as a manifestation of large cell lymphoma.

A leukaemic phase is uncommon in large cell lymphoma, particularly at presentation of the disease, and very few cases have been reported since immunological markers became available. We have studied 24 cases presenting over a period of 15 years. 16 were B-lineage and eight T-lineage. In five patients the large cell lymphoma represented a transformation of a preceding low grade, small cell lymphoproliferative disease. Three other patients with T-lineage large cell lymphoma presented with skin infiltration (two cases) or lymphoma-associated nephrotic syndrome (one case) 3-9 months before leukaemia occurred. The other 16 patients (12 B-lineage and four T-lineage) presented with de novo large cell leukaemia/lymphoma. With the exception of skin infiltration, clinical features did not differ between T and B-lineage cases. Prognosis was generally poor although a minority of patients lived 1-2 years. Median survival was 7 months. In the B-cell lymphomas immunological markers were those expected but among the T-cell cases there were many unusual immunophenotypes with frequent failure to express markers which are usually positive in peripheral T cells. Without the availability of immunological markers diagnosis would have been difficult, with acute myeloid leukaemia being the most important differential diagnosis. T-lineage and B-lineage cases could not be distinguished on cytological features. In the majority of cases the cells were very pleomorphic with nuclear lobulation, prominent nucleoli and marked cytoplasmic basophilia being commonly observed. Marked nuclear lobulation was not confined to T-lineage cases but was seen also in seven of 12 cases of de novo B-lineage leukaemia/lymphoma; it was readily apparent in histological sections and on ultrastructural examination.

Adolescent↗
PubMed1991

Atypical Ph negative chronic myeloid leukaemia presenting as sudden profound deafness.

A patient with atypical Ph negative chronic myeloid leukaemia presented with the sudden onset of profound deafness. He survived only eight months. Detailed histological investigation performed at necropsy showed loss of ganglion cells and afferent nerve fibres in the cochlea and vestibule associated with extensive fibrosis and new bone formation in the labyrinthine spaces. Both leucophoresis and high dose chemotherapy capable of rapid cytoreduction are recommended in patients with chronic myeloid leukaemia with profound hearing loss, as conventional chemotherapy is rarely followed by recovery.

Deafness↗
PubMed1989

The influence of adaptive seating devices on vocalization.

This study examined the relationship between receipt of adaptive seating devices (ASD) and sophistication of early vocalizations/verbalizations. Eight nonverbal children with cerebral palsy were studied prior to and following receipt of an ASD. Total speech tokens increased for 7 of the 8 subjects and diversity of speech sounds increased for 6 subjects. A concomitant improvement in feeding independence was observed for those subjects who demonstrated the greatest increase in speech sound diversity.

Cerebral Palsy↗