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Biomedical subjects

J Allen

Publications and source records attributed to J Allen.

At least 199 records · Page 11Linked to original sources
PubMed1996

Studies of antibodies in the sera of patients who have made red cell autoantibodies.

BACKGROUND: In patients in whom autoantibodies of broad specificity (panagglutinins) are present in the serum, adsorption studies are often necessary to identify alloantibodies that are simultaneously present. STUDY DESIGN AND METHODS: Samples from 138 patients in whom the direct antiglobulin test was positive and antibody was present in the serum were studied. When antibody identification studies before or after initial adsorption suggested the presence of an alloantibody, additional alloadsorptions were performed. RESULTS: Among the samples from 138 patients, 71 contained only panagglutinating autoantibody, and another 19 contained either autoantibodies or alloantibodies that were not accompanied by panagglutinins. The remaining 48 samples contained both panagglutinins and a total of 62 antibodies that appeared to be alloimmune in nature. Alloadsorption with antigen-negative red cells showed that 29 (47%) of the apparent alloantibodies were in fact partially adsorbed autoantibodies that mimicked alloantibodies by their reactions. CONCLUSION: Initial autoadsorption often left unadsorbed alloantibodies and autoantibodies with mimicking specificities. Initial alloadsorption more often left only true alloantibodies unadsorbed. From the screening tests, it appeared that 43 percent of the 138 patients were alloimmunized. Recognition of the mimicking nature of the partially adsorbed autoantibodies found that the real incidence of alloimmunization in the patients was 23 percent. Recognition of this phenomenon considerably simplifies the selection of blood for transfusion to these patients.

Autoantibodies↗
PubMed1996

Anti-Di(b) as a red cell autoantibody.

BACKGROUND: It is known that some "warm"-reactive autoantibodies are directed against epitopes on the red cell anion exchanger, protein band 3. Some such antibodies (but not all) recognize Wrb. It is also known that Dia and Dib represent an amino acid polymorphism of band 3. STUDY DESIGN AND METHODS: Autoantibodies from 119 patients were tested against Di(b-) red cells. Seventy-four of these autoantibodies were subsequently absorbed with Di(b-) red cells. RESULTS: All 119 autoantibodies initially reacted with the Di(b-) red cells, which showed that none contained only anti-Dib. Among the 74 adsorbed with Di(b-) red cells, two were found to contain an unadsorbed anti-Dib component. CONCLUSION: No example of autoanti-Dib as the only autoantibody present was found among the 119 samples tested. However, 2 (2.7%) of 74 autoantibodies subjected to adsorption with Di(b-) red cells were seen to contain an anti-Dib component. This low incidence of autoanti-Dib is in marked contrast to the high incidence of autoanti-Wrb, although both antibodies define epitopes associated with the red cell anion exchanger, band 3.

Anemia, Hemolytic↗
PubMed1996

Assessing ECG signal quality on a coronary care unit.

Poor electrocardiograph (ECG) signal quality is associated with an increase in the number of false alarms, may degrade diagnostic information, and can increase the workload for coronary care unit (CCU) or other intensive care staff. It is important therefore to establish simple quantitative measures that can be used to demonstrate signal quality problems. In this study, a fixed-gain diagnostic bandwidth ECG from patients in a single CCU bed was monitored continuously for 10 weeks and measures which could relate to quality were calculated. These measures were the number of times the ECG exceeded a preset limit (out-of-range events, +/-4 mV) and the frequency content of the ECG plus superimposed noise in six different bandwidths (0.05-0.25, 0.25-10, 10-20, 20-48, 48-52, and 52-100 Hz). A computer-based data collection system calculated a 10 s average for each of the measures and logged these to memory. Following the data collection phase, good-quality baseline levels for the seven measures were calculated for each of the days studied and compared with levels during the evening-night (6 pm-6 am), which were in turn compared with levels during the day-time (6 am-6 pm). All measures were significantly lower (p < 0.001) for the selected good-quality ECGs compared with those recorded during the night, with low frequency, lower ECG bandwidth, and out-of-range events producing the greatest differences. Night-time noise levels were lower than day-time levels, and the largest reductions were found in the rate of out-of-range events (19.8 to 9.3 h-1) (p < 0.02), and low-frequency content less than 0.25 Hz (70 to 56 microV) (p < 0.01). Significant reductions during the night were also found in the lower ECG bandwidth 0.25-10 Hz (111 to 98 microV) (p < 0.01). No significant changes were found in the higher frequencies. We conclude that the low-frequency content and rate of out-of-range events are easy to obtain and could be used as measures for evaluating signal quality.

Coronary Care Units↗
PubMed1996

Between the trapezes--making the most of change.

This paper recounts the author's own experience of mismanaging change and describes the unfortunate outcome. Two theories are introduced and applied retrospectively to the case cited in order to identify how it could have been handled more sensitively and successfully. The first theory relates to the stages involved in the process of change as described by William Bridges. The second refers to the specific relationship between the psychometric instrument, Myers Briggs Type Indicator (MBTI) and the different ways in which individuals are likely, and to a certain extent can be predicted to behave in a time of change.

Adaptation, Psychological↗
PubMed1996

Pharmacotherapies for alcohol problems: a review of research with focus on developments since 1991.

Research on medications to treat alcohol problems has flourished in the last 5 years. Whereas before this time most projects focused on withdrawal agents, at least equal interest has now extended to drugs that may directly reduce urge to drink. The most promising medications in this regard are the opiate antagonists and acamprosate. Considerable attention has also been devoted to serotonergic agents. As aids to detoxification, pharmacologic agents that affect the multiple neural systems disrupted by acute alcohol withdrawal remain under active investigation. Significant progress is also being made in identifying medications to assist alcoholics suffering collateral psychopathology, especially depression and anxiety based disorders. Unfortunately, fewer gains have been realized in the development of medications to assist patients simultaneously dependent on both alcohol and illicit drugs. Also, research to develop amethystic agents remains in its very early stages.

Acamprosate↗
PubMed1996

Comparison of lower limb arterial assessments using color-duplex ultrasound and ankle/brachial pressure index measurements.

The strength of agreement between two noninvasive methods of assessing lower limb arterial disease and their relationship to patient symptoms following exercise have been investigated. Color-duplex ultrasound (CDU) and ankle/brachial pressure index (ABPI) (before and afer exercise) measurements were obtained from 200 consecutive patients referred to a vascular investigations laboratory. From these patients, 290 limbs were available for study, comprising limbs without previous vascular surgery, from patients without diabetes and who could attempt a walking exercise test. The overall level of agreement between CDU and resting ABPI measurements was 83% (Kappa 0.66). The ABPI technique identified the more serious disease; a resting ABPI of less than 0.6 gave 100% agreement with CDU. With higher resting ABPIs the level of agreement became poorer: 83% (0.6 < or = ABPI <0.9) and 76% (normal ABPI > or = 0.9). The addition of postexercise ABPI measurements in determining significant arterial disease increased the strength of relationship between the two techniques by only 2% (85%, Kappa 0.69). The exercise test was generally limited by the most symptomatic limb in each patient, and the agreement between CDU and postexercise ABPI measurements in these limbs was higher at 93% (Kappa 0.81). In comparison, agreement for the least symptomatic group of limbs was found to be poor (69%, Kappa 0.37). Compared with symptoms after exercise, overall agreements with CDU and ABPI were both 67% (Kappa 0.27). The agreement was better (91%) when the resting ABPI was less than 0.6. The ABPI is biased toward the detection of more severe disease and is more consistent with CDU when the most symptomatic limbs are compared. The relationship between either test and symptoms after exercise is strong only for limbs with major disease.

Adult↗
PubMed1996

Depression and multiple sclerosis.

The objective of the present study were (1) to ascertain the lifetime risk of a depression in a representative group of multiple sclerosis (MS) patients, (2) to assess the morbidity risks for depression among first-degree relatives of these MS patients, and (3) to compare these familial risks for first-degree relatives of MS patients with those for first-degree relatives of a primary depression population, i.e., depression but no MS. We psychiatrically evaluated 221 MS patients (index cases) using a structured clinical interview for the DSM-III-R and calculated the rate and lifetime risk of depression for these index cases using the product limit estimate of survival function. We obtained psychiatric histories for all first-degree relatives of index cases, and we calculated morbidity risks for depression for these relatives using the maximum likelihood approach and compared the risks using the likelihood ratio tests. Index cases had a 50.3% lifetime risk of depression. Morbidity risks for depression among first-degree relatives of index cases were decidedly lower when compared with morbidity risks among first-degree relatives of the reference population. Although there appears to be a very high rate of depression among MS patients, the data for their first-degree relatives do not support a clear genetic basis for this depression, or at least the same genetic basis that probably operates within families when depression occurs in the absence of MS.

Adolescent↗
PubMed1996

Quality of care and cost-containment in managed mental health: policy, education, research, advocacy.

Managed mental health care cost-containment practices of risk-benefit analysis, provider usage, manipulation of supply and demand, gate keeping, medical necessity, and formulation have adversely affected quality of care. Improved mental health services are dependent upon redefining mental health problems and understanding inequities created by medicalization as means to limit access to services. This dilemma can be addressed by development of mental health policy, public education, and political advocacy. An immediate role for professional psychology is found in the creation of a research agenda that documents empirically supported interventions for specific mental health problems, mechanisms of effective and acceptable service-delivery, and identification of providers with demonstrated clinical skills, including cultural competencies.

Cost Control↗
PubMed1996

Replication and extension of Marlatt's taxonomy of relapse precipitants: overview of procedures and results. The Relapse Research Group.

The Relapse Replication and Extension Project (RREP) was a multisite study to replicate and extend Marlatt's taxonomy of relapse precipitants. In addition to replicating Marlatt's original taxonomic system, three independent research teams utilized prospective designs to identify additional predictors of relapse and developed and evaluated two alternative systems for assessing high risk relapse situations. This overview describes the replication methodology, summarizes seven RREP studies completed by the three research groups, and discusses five cross-cutting conclusions emerging from the studies. These conclusions are: (1) reliability of Marlatt's taxonomic system was variable both within and across the three research sites; (2) Marlatt's taxonomic system showed little predictive validity in analyses that used pretreatment relapse data to predict post-treatment relapse, but there are important unresolved issues; (3) an alternative taxonomy provided little more predictive validity than the original taxonomy even though it measured more dimensions of relapse situations and provided greater analytic flexibility; (4) the Reasons for Drinking Questionnaire appeared to be a successful psychometric transformation of Marlatt's taxonomy, one which did demonstrate predictive validity; and (5) Marlatt's taxonomy was based on a time-intensive model of relapse prediction whereas RREP prospective analyses represented time-extensive models of relapse prediction. Coping responses are noted to be effective predictors of relapse under both models.

Adult↗
PubMed1995

Linguistic aspects of speech synthesis.

The conversion of text to speech is seen as an analysis of the input text to obtain a common underlying linguistic description, followed by a synthesis of the output speech waveform from this fundamental specification. Hence, the comprehensive linguistic structure serving as the substrate for an utterance must be discovered by analysis from the text. The pronunciation of individual words in unrestricted text is determined by morphological analysis or letter-to-sound conversion, followed by specification of the word-level stress contour. In addition, many text character strings, such as titles, numbers, and acronyms, are abbreviations for normal words, which must be derived. To further refine these pronunciations and to discover the prosodic structure of the utterance, word part of speech must be computed, followed by a phrase-level parsing. From this structure the prosodic structure of the utterance can be determined, which is needed in order to specify the durational framework and fundamental frequency contour of the utterance. In discourse contexts, several factors such as the specification of new and old information, contrast, and pronominal reference can be used to further modify the prosodic specification. When the prosodic correlates have been computed and the segmental sequence is assembled, a complete input suitable for speech synthesis has been determined. Lastly, multilingual systems utilizing rule frameworks are mentioned, and future directions are characterized.

Communication↗
PubMed1995

Proviral tagging in E mu-myc transgenic mice lacking the Pim-1 proto-oncogene leads to compensatory activation of Pim-2.

The Pim-1 proto-oncogene is one of the most potent collaborators of the myc proto-oncogenes in inducing lymphomagenesis in mice. Contrary to the profound effects when overexpressed in vivo, Pim-1-deficient mice showed only subtle phenotypic alterations, which could indicate the presence of redundantly acting genes. In line with this, a PCR-based screen has led to the identification of a closely homologous gene, Pim-2. The X-linked Pim-2 gene is 53% identical to Pim-1 at the amino acid level and shares substrate preference and the usage of non-AUG initiation codons with Pim-1. We have used these data to test whether the strong synergistic interaction between Pim-1 and c-myc can be utilized to gain access to Pim-1 compensatory pathways. We reasoned that, upon proviral tagging in compound mutant mice (E mu-myc/Pim-1-/- mice), the selective advantage of cells carrying provirally activated genes, that act downstream from or parallel to Pim-1, would increase. We show here that this is the case. A dramatic increase (from 15 to 80%) was found in the frequency of proviral activation of the Pim-2 gene. These data show that the described strategy of 'complementation tagging' represents a powerful new tool to identify components of pathways involved in processes as complex as multistep tumorigenesis.

Amino Acid Sequence↗
PubMed1995

Binding of [3H]cirazoline to an imidazoline site in rat brain and kidney membranes.

Two classes of high-affinity sites for [3H]cirazoline were characterized in rat brain and kidney membranes. In both tissues, the binding parameters for the high- and low-affinity sites are similar with Bmax values of approximately 50 fmol/mg protein, Kd approximately 0.6 nM and Bmax approximately 470 fmol/mg protein, Kd approximately 11 nM respectively. Inhibition studies of [3H]cirazoline binding to the lower affinity site revealed that only guanidinium or imidazoline derivatives compete with the specific binding of this radioligand. Our results suggest that [3H]cirazoline could be used as a novel ligand to label the non-adrenergic imidazoline-preferring sites.

Animals↗
PubMed1995

CD36 gene transfer confers capacity for phagocytosis of cells undergoing apoptosis.

Phagocyte recognition and ingestion of intact cells undergoing apoptosis are key events in this generally important program of cell death. Insufficient phagocyte capacity for apoptotic cells can result in failure to clear dying cells before membrane integrity is lost, resulting in leakage of noxious cell contents and severe tissue damage. However, no means has been available to increase phagocytic clearance of apoptotic cells. We now report that transfection of the macrophage adhesion molecule CD36 into human Bowes melanoma cells specifically conferred greatly increased capacity to ingest apoptotic neutrophils, lymphocytes, and fibroblasts, comparable to that exhibited by macrophages. Furthermore, when CD36 was transfected into another cell type with limited capacity to take up apoptotic bodies, the monkey COS-7 cell, similar effects were observed. Therefore, CD36 gene transfer can confer "professional" capacity to ingest apoptotic cells upon "amateur" phagocytes.

Animals↗
PubMed1995

Biosphere 2.

Explore the source record for details and available documents.

Ecological Systems, Closed↗
PubMed1995

Modulation of cell phenotype in human osteoblast-like cells by the simian virus 40.

At present, the majority of in vitro research into bone metabolism is performed on either primary cultures of bone or osteosarcoma lines. A better model of the behaviour of normal bone cells would be a cell line derived from normal, adult bone that retained osteoblast-like characteristics. We infected a culture of bone cells from adult humans with simian virus 1613, a variant of the simian virus 40, and obtained 12 clones of variable morphology. The clones were maintained in culture for as long as 6 months. Population doubling times, synthesis of alkaline phosphatase and osteocalcin, secretion of mineral, morphology, and ability to withstand freezing were examined. SV/EC cell morphology varied from the polygonal, osteoblast-like to the bipolar, fibroblast-like. Population doubling times ranged from 0.55 to 2.8 days (compared with 3.9 days for the nontransformed human osteoblast-like cells). Synthesis of alkaline phosphatase varied but was less than that by the human osteoblast-like cells. With the exception of clone 11, all of the transformed clones synthesised mineral in vitro under mineralising conditions. Four clones showed increased synthesis of alkaline phosphatase and increased population doubling times after passaging. All of the clones were successfully frozen and thawed, but, unlike normal human osteoblast-like cells, none responded to stimulation with parathyroid hormone.(ABSTRACT TRUNCATED AT 250 WORDS)

Alkaline Phosphatase↗