Search PubMed⌕ Search

Biomedical subjects

M L Brigden

Publications and source records attributed to M L Brigden.

At least 37 records · Page 2Linked to original sources
PubMed1996

The antiphospholipid syndrome: when does the presence of antiphospholipid antibodies require therapy?

To avoid wasting healthcare resources through overinvestigation in otherwise healthy people, it is important to remember that antiphospholipid antibodies (ie, lupus anticoagulant and anticardiolipin antibody) often do not signify clinical disease. However, when features of the antiphospholipid syndrome (APS) are also present, serious thrombosis may be expected. Exactly how these antibodies alter hemostasis to induce a hypercoagulable state remains unclear. Activated partial thromboplastin time may not be a reliable screening test in a minority of patients with lupus anticoagulant and is not useful in screening for anticardiolipin antibodies. When APS is strongly suspected on clinical grounds, definitive tests (ie, enzyme-linked immunosorbent assay for IgG, IgA, and IgM anticardiolipin antibodies and the dilute Russell's viper venom time test) followed by confirmatory tests (eg, for lupus anticoagulant) should be ordered. Patients with APS are at high risk for recurrent thrombosis, but questions about optimal clinical management remain unresolved. High-intensity or lifelong anticoagulation therapy should be considered in some cases. Low-molecular-weight heparin may ultimately prove to be the treatment of choice in pregnant APS patients.

Antibodies, Antiphospholipid↗
PubMed1996

Oral anticoagulant therapy: practical aspects of management.

Careful attention to the practical aspects of oral anticoagulant therapy can improve patient compliance and lessen the risk of bleeding complications. A variety of risk factors for bleeding associated with oral anticoagulant therapy have been defined and should be assessed before initiating therapy. Recent investigations have provided a means for estimating what constitutes a significant change in an individual patient's serial International Normalized Ratio (INR) by allowing for combined analytic and biologic variation in prothrombin time determinations. Dosing adjustments with warfarin sodium (Coumadin, Panwarfin, Sofarin) should be appropriate to the level of the INR and spread over the total weekly dosage for optimum stable control. Elderly patients are more sensitive to any given dose of warfarin and need a significantly lower total weekly dose. Attention must be paid to the vitamin K content of the diet and a variety of additional factors, including other drug therapy, alcohol consumption, and metabolic status. Hematuria or gastrointestinal bleeding should always be assessed, because the chance of finding a clinically significant lesion is good, especially when the INR has been in the therapeutic range. Although a minor prolongation of the INR without bleeding may be treated by watchful waiting, vitamin K administration and other therapeutic measures may be necessary for active bleeding. Comprehensive patient education is paramount and may be facilitated by a checklist approach. A well-informed patient provides one of the best defenses against bleeding complications.

Administration, Oral↗
PubMed1995

When bleeding complicates oral anticoagulant therapy. How to anticipate, investigate, and treat.

With use of the International Normalized Ratio (INR), physicians can accurately assess the intensity of anticoagulation in treatment programs and trials. Bleeding is the major complication of oral anticoagulant therapy, and its incidence can be lessened, with no loss of efficacy, by using less intense therapy (INR, 2 to 3). INRs above the target range, marked variability in INRs, newly initiated therapy, previous bleeding, and a serious comorbid condition all constitute significant risk factors. While age over 65 is not a proven risk factor, the elderly are more sensitive to the effects of warfarin and require smaller doses. Meticulous attention should be paid to the concomitant use of any medications that may affect metabolism of warfarin or induce a concomitant qualitative platelet effect (specifically, aspirin and nonsteroidal antiinflammatory drugs) and to dietary modifications that significantly change vitamin K intake. Hematuria or gastrointestinal bleeding should always be assessed, since the chance of finding a clinically significant lesion is good, especially when the INR has been in the therapeutic range. While a minor prolongation of the INR without bleeding may be treated by watchful waiting, vitamin K administration and other therapeutic measures may be necessary in patients who are actively bleeding.

Adult↗
PubMed1995

A systematic approach to macrocytosis. Sorting out the causes.

Because of the widespread use of multiparameter hematology instruments, physicians are often presented with patients who have macrocytosis with no obvious cause. Depending on the demographics of an individual practice, folate and vitamin B12 deficiencies may be relatively rare causes of macrocytosis, compared with alcoholism, liver disease, drugs, or myelodysplasia. Initial evaluation should include a carefully taken history and physical examination along with a complete hematologic profile, reticulocyte count, and peripheral blood smear. This initial evaluation should allow systematic consideration of the possible causes. Serum B12 and red cell folate determinations and other studies may then be undertaken as appropriate.

Adult↗
PubMed1995

Unproven (questionable) cancer therapies.

More than half of all cancer patients use some form of alternative treatment during the course of their illness. Alternative therapies are often started early in patients' illness, and their use is frequently not acknowledged to health care professionals. Some alternative therapies are harmful, and their promoters may be fraudulent. Persons who try alternative cancer therapies may not be poorly educated but may ultimately abandon conventional treatment. Recent attention has focused on aspects of questionable therapies that make these treatments attractive to patients and that may be perceived as being deficient in the practice of conventional health care professionals. Physicians with patients with cancer should always make sure that unproven therapies are discussed early in the therapeutic relationship. They should also attempt to be aware of alternative therapies that are in vogue in their particular geographic area.

Complementary Therapies↗
PubMed1993

Macrophage-tumor cell associations: a factor in metastasis of breast cancer?

In human breast carcinomas tumor cells and macrophages are often proximal. We previously reported on the relationship between tumor cell growth and macrophage concentration and report here on the possible involvement of macrophages in the metastatic process. We hypothesize that during the initial stages of metastasis, tumor cells are likely to encounter macrophages and form aggregates. Using a cell culture method that encourages cellular interactions, we found aggregates involving macrophages. Macrophages partly or completely surround other cell types without any apparent ill effect. Units involving macrophages and tumor cells would possess many properties necessary for invasion, which is a normal process for macrophages. Properties such as motility and production of specific enzymes necessary to traverse the extracellular matrix, basement membrane, and endothelial cell barriers may provide an advantage for tumor cells. Physical support and protection from immune recognition during transport of the tumor cell through the vascular system may also be enhanced, and paracrine growth stimulation and angiogenic activity may be provided at the new metastatic site. Verification of these observations in vivo could lead to new directions for limiting breast cancer metastasis.

Breast Neoplasms↗
PubMed1993

Iron deficiency anemia. Every case is instructive.

Awareness of subtle symptoms of mild iron deficiency is increasing, but unsuspected iron deficiency is a persistent problem, especially among certain groups, such as menstruating women and milk-fed infants. The diagnosis must be clearly established through appropriate testing, and an underlying cause should always be sought. Useful tests include determination of serum ferritin and iron levels and of iron-binding capacity. A nomogram is available that correlates the serum ferritin value with the degree of inflammation present, but in some patients, bone marrow aspiration and iron staining is still required. When oral iron therapy is undertaken, an appropriate non-enteric-coated, non-sustained-release preparation should be chosen. Gradually increasing the amount of iron supplementation and taking the tablets with meals help limit side effects and ensure patient compliance. Iron therapy should be continued for 6 months after the hemoglobin level returns to normal so that total iron stores are replaced. Follow-up to ensure that iron deficiency anemia has not recurred and that the diagnosis was correct is required.

Adenocarcinoma↗
PubMed1993

Evaluation of the Sysmex NE-8000. Automated hematology analyzer in a high-volume outpatient laboratory.

An evaluation of SYSMEX NE-8000 (Toa Medical Electronics Co., Ltd., Kobe, Japan) hematology analyzer, including its automated five-part white blood cell (WBC) differential count, was performed in a high-volume outpatient laboratory. Precision, mixing studies, stability, carry-over, and linearity were all within the limits stated by the manufacturer. Evaluation of the five-part WBC differential revealed excellent correlation with manual differential neutrophil and lymphocyte counts. Monocyte, eosinophil, and basophil data were acceptable given the known poor precision of 200 cell manual WBC differential counts when low percentages of individual cell types are present. Overall, flagging for morphologic abnormalities displayed a sensitivity of 87% and a specificity of 97%. The combination of the flagging system with the visual record provided by the NE-8000 WBC histogram represents an effective tool for separating normal from abnormal specimens, and allows considerable selectivity in the performance of follow-up manual WBC differential counts.

Hematology↗
PubMed1992

Oral anticoagulant therapy. Newer indications and an improved method of monitoring.

Oral anticoagulants remain time-tested therapeutic agents. A number of new indications for use of these drugs have recently emerged, especially nonvalvular atrial fibrillation. New information on the factors associated with adverse reactions to oral anticoagulants is available, along with improved knowledge on how to evaluate and treat such complications. A major advance in the safer use of these drugs in North America will accompany increased application of the International Normalized Ratio in reporting prothrombin time.

Administration, Oral↗
PubMed1992

Overwhelming postsplenectomy infection still a problem.

Despite an extensive medical literature over the past ten years, patients continue to die needlessly of overwhelming postsplenectomy infection. Although physicians have become increasingly cognizant of this syndrome in children, many remain unaware of the risk to asplenic or hyposplenic adults with no underlying medical problems. In addition, many older asplenic or functionally hyposplenic persons are unaware that they are at risk for this syndrome. The identification of Howell-Jolly bodies on a peripheral blood smear should alert physicians to the need for further follow-up to establish hyposplenism and to consider possible antipneumococcal vaccination.

Adult↗
PubMed1992

High incidence of significant urinary ascorbic acid concentrations in a west coast population--implications for routine urinalysis.

Examination of 4379 routine urinalysis specimens with dipsticks sensitive to ascorbic acid showed that 22.8% were positive specimens. The mean urinary vitamin C concentration in this population was 2120 mumol/L. There was a high rate of false-negative dipstick results for hemoglobin in patients with vitamin C in the urine. The highest false-negative rates were observed in urine samples containing less than 50 erythrocytes per high-power field. In further experiments when volunteers consumed supplemental oral USP vitamin C at doses of 100, 250, 500, and 1000 mg or vitamin C-containing fruit juices, even the lowest doses of oral vitamin C or juice resulted in sufficient urinary vitamin C to produce false-negative dipstick results in hemoglobin and glucose testing. To prevent potentially dangerous false-negative results, screening urinalysis protocols relying only on dipstick testing should include a check for urinary vitamin C or use a dipstick that is not subject to vitamin C interference.

Ascorbic Acid↗
PubMed1991

The relationship between the absolute granulocyte count, platelet count and total leukocyte count in cancer chemotherapy patients.

A cohort of 383 patients with a variety of malignancies receiving various chemotherapy programs was analyzed to determine the relationship between the absolute granulocyte count (AGC) and the total leukocyte count (TLC). Specific groups, who were elderly, had proven bone marrow involvement, or were receiving significant doses of prednisone, were studied. The relationship between the TLC and thrombocytopenia was also examined. Results revealed that in all groups there was a correlation between the TLC and the AGC with correlation coefficients ranging from 0.82 to 0.88. Both life-threatening thrombocytopenia and granulocytopenia were rare, providing and TLC was greater than 3.0 x 10(9)/L.

Adolescent↗
PubMed1990

The optimum urine collections for the detection and monitoring of Bence Jones proteinuria.

Twenty patients with malignant disease and Bence Jones (BJ) proteins were studied to determine the optimum urine collections for the detection and monitoring of light chain proteinuria. A 24-hour urine protein collection was followed by individual collections of each sequentially voided specimen over the same time interval. Samples were analyzed quantitatively for protein, and protein electrophoresis was performed on each specimen. Only one patient had BJ protein nondetectable by protein electrophoresis in the early morning specimen. Six patients had one or more random specimens (excluding the early morning specimens) absent for BJ protein on protein electrophoresis. Three patients had nondetectable protein on electrophoresis of the 24-hour specimen despite having some random specimens positive. All random specimens with protein values exceeding 0.20 g/L had BJ protein visibly detectable on electrophoresis. Thirteen specimens with protein less than 0.05 g/L still had BJ protein detected by electrophoresis. There was a linear relationship between the early morning protein concentration and the total 24-hour urinary protein production. The authors conclude that early morning specimens or 24-hour urine collections are preferable for the detection and monitoring of light chain proteinuria. These collection methods are not mutually exclusive because there are individual patients who will be negative in one collection but positive in the other.

Aged↗
PubMed1990

The lack of clinical utility of white blood cell differential counts and blood morphology in elderly individuals with normal hematology profiles.

An investigation of 462 patients aged older than 65 years with normal hematology profiles revealed 105 individuals with unsuspected abnormalities in the white blood cell differential count, peripheral blood film, or platelet count. In only 8 patients would this information have resulted in additional patient testing or other changes in management. The availability of instrumentation providing an automated platelet count would have decreased the number of patients experiencing a change in management to 5. In no instance did physicians believe that an individual patient's clinical outcome would have been altered by a knowledge of the unexpected abnormalities or the anticipated management changes. In an ambulatory adult population with normal hematology profiles, there is limited clinical value in pursuing further studies, such as a white blood cell differential count or an examination of the red blood cell morphology.

Aged↗