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Biomedical subjects

R D Barr

Publications and source records attributed to R D Barr.

At least 73 records · Page 4Linked to original sources

Disseminated Langerhans cell histiocytosis in identical twins unresponsive to recombinant human alpha-interferon and total body irradiation.

Monozygotic twin boys presented at 1 year of age with seborrheic skin rash, otorrhea, and hepatosplenomegaly. Skin biopsy confirmed Langerhans cell histiocytosis. Treatment with conventional antineoplastic drugs and with calf thymus extract was ineffective. The disease remained refractory to recombinant human alpha-interferon and to low-dose total body irradiation, and the children died between 3 and 3 1/2 years of age.

Combined Modality Therapy↗

A comprehensive multiattribute system for classifying the health status of survivors of childhood cancer.

PURPOSE: A multiattribute health status classification system was devised to describe comprehensively the health status of survivors of childhood cancer. METHODS: The system consists of seven attributes: sensation, mobility, emotion, cognition, self-care, pain, and fertility. Three to five levels of functioning are defined for each attribute. Any specific combination of seven attribute levels constitutes a health state. In the first survey, the system was used to classify the health status of 20 children currently undergoing therapy for high-risk acute lymphoblastic leukemia (ALL), Wilms' tumor, or neuroblastoma, and eight who had completed treatment. A second survey consisted of 13 children with brain tumors on active treatment. RESULTS: In general, independent ratings by clinicians were in agreement, and consensus was readily achieved in 1 to 2 minutes per patient. Children on therapy experienced a higher burden of morbidity than those off treatment. Brain tumor patients experienced more morbidity than patients in the first survey. CONCLUSION: The multiattribute system provides a compact but comprehensive tool for long-term follow-up of survivors of childhood cancer. It captures both multiple sequelae and varying levels of severity. By using a mathematical utility function, a single summary score of health-related quality of life may be assigned to each health state. Additional studies to establish reproducibility, validity, responsiveness, and generalizability are indicated.

Activities of Daily Living↗

The short-term reproductive toxicity of cyclophosphamide in the female rat.

Cyclophosphamide (CTX) is a potent ovarian toxicant. Previous studies of the acute effects of CTX in the rat have demonstrated widespread ovarian follicle atresia, reduced serum estradiol, and progesterone with normal serum LH and FSH. The present investigations demonstrate that a single injection of CTX induces ovarian toxicity that reflects the loss of growing ovarian follicles. CTX induces a sensitization of serum FSH in response to GnRH within 24 h; this sensitization is lost by 7 days, and after 14 days the animals are capable of normal mating behavior. The observed protection of primordial follicles from the acute administration of CTX under these experimental circumstances may be related to the stage of the granulosa cell cycle of these follicles.

Animals↗

The agonist (d-leu-6,des-gly-10)-LHRH-ethylamide does not protect the fecundity of rats exposed to high dose unilateral ovarian irradiation.

Attempts to protect the ovary from the toxic effects of radiation and chemotherapy are relevant to the management of the young patient with cancer. Previous studies in a variety of animal species with several types of agonists of GnRH have shown promise in affording gonadal protection using indirect indices of reproductive function. The current investigations are based on these observations. Female rats were treated with (d-leu-6,des-gly-10) LHRH-ethylamide (GnRHa) from day 22 to day 37 of life. Sham-irradiation or unilateral irradiation of the left ovary was performed on day 30. The animals were mated following resumption of cycles and sacrificed on day 21 of pregnancy. There was no significant effect of ovarian artery ligation. Radiation reduced ovarian function ipsilateral to the radiation. GnRHa alone did not affect reproductive performance significantly. GnRHa and radiation combined resulted in no reproductive protection but augmented the damage done to the ipsilateral ovarian weight and to numbers of corpora lutea and fetuses. Under these experimental circumstances the agonist provided no protection.

Animals↗

Right atrial catheters in children with cancer: a decade of experience in the use of tunnelled, exteriorized devices at a single institution.

In the period 1980-1988, data were collected (prospectively from 1985) on the clinical utilization of exteriorized, tunnelled, right atrial catheters in children with cancer undergoing treatment at a single institution. A total of 231 devices were placed in 180 patients. Individual catheters were in place for a median of 314 days, with a total experience of more than 83,000 days. This form of long-term venous access was used for the administration of antineoplastic agents and other drugs, blood products (especially platelet concentrates and packed red blood cells), parenteral nutrition and infusion of other fluids, obtaining samples of venous blood, and giving intravenous contrast media and radiolabeled substances for radiological investigations. Almost 80% of catheters were removed electively (on completion of scheduled therapy or at death), with the remainder requiring removal in the management of infection or device displacement. Infections were manifest in two-thirds of the children, most commonly (60%) at the catheter exit site on the anterior chest wall. "Clinically significant" infection occurred with a frequency of 2.1 episodes per 1,000 patient days, with Staphylococcal species predominating except for the circumstances of catheter colonization in which Gram-negative, waterborne organisms were most in evidence. Empirical, intravenous, combined antibiotic therapy was effective in approximately 90% of "clinically significant" episodes. Mechanical complications (traveling, leakage, or catheter occlusion) occurred less frequently and were managed by repairing or replacing the device, or clearing the block. Indwelling catheters, of the Broviac or Hickman types, offer major advantages with acceptable morbidity in the management of children with malignant diseases.

Adolescent↗

Recurrent acute splenic sequestration crisis due to interacting genetic defects: hemoglobin SC disease and hereditary spherocytosis.

A 14-year-old boy with hemoglobin SC disease and alpha-thalassemia-2 experienced five episodes of acute splenic sequestration crisis (ASSC), while two of his siblings with identical globin genotypes (SC and -alpha/alpha alpha) had no such experience. To determine if an additional red blood cell (RBC) defect was responsible for the unusual occurrence of frequent ASSCs, we performed detailed rheologic characterization and membrane protein analysis on RBCs from the proband and other members of his family. Reduced surface area, increased mechanical instability, and decreased spectrin content of the membrane, distinguishing features of RBCs in hereditary spherocytosis, were observed in cells from the proband and his mother, but not in cells from other family members. These findings are consistent with the dominant inheritance of spherocytosis by the proband. We suggest that the combined effects of SC disease and spherocytosis in the proband resulted in decreased RBC deformability and led to increased splenic trapping, intrasplenic sickling, and consequently, recurrent sequestration crisis. Marked clinical and hematologic improvement occurred from splenectomy. Thus, inheritance of interacting genetic defects, sickling hemoglobinopathy, and hereditary spherocytosis appear to be responsible for the unusual clinical manifestation of recurrent ASSC in this patient.

Anemia, Sickle Cell↗

Acetylcholinesterase in the human erythron. III. Regulation of differentiation.

Acetylcholinesterase (AChE) is present in both primitive and mature erythroid cells, but a role for the enzyme in human hematopoiesis has not been defined. This prospect represented the primary objective of the following study. In clonal culture of normal human bone marrow cells, a "wave" of AChE activity was demonstrated, rising from undetectable levels to a peak (of 1.48 femto-moles per min per cell) at 10 days in the course of progressive erythroid clonogenesis. At concentrations of enzyme inhibitor that clearly reduced AChE activity in a dose-dependent fashion, there was no overall effect on erythropoiesis in vitro, but the clones were generally smaller and significantly more often multi-focal than in control cultures. Furthermore, in the presence of AChE inhibitors, a concentration-dependent increase in the myeloid-erythroid ratios of the culture harvests was observed. Likewise, a clear reduction in hemoglobination was revealed, in cells of 10 day cultures, from a mean hemoglobin concentration of 35.0 pg per cell in controls to 20.1 pg per cell in the presence of the maximal concentration of the inhibitor (10(-6) M eserine). These data point to a role for AChE in the regulation of differentiation in the human erythron.

Acetylcholinesterase↗

Management of Ontario children with acute lymphoblastic leukemia by the Dana-Farber Cancer Institute protocols.

There is ample evidence of the value of intensive therapeutic strategies in the management of acute lymphoblastic leukemia (ALL), the commonest form of malignant disease in children. Such a program, devised at the Dana-Farber Cancer Institute (DFCI), Boston, and incorporating high-dose L-asparaginase, was adopted in 1984 by the Children's Hospital at Chedoke-McMaster, Hamilton, Ont., and the Children's Hospital of Western Ontario, London. We describe the experience of these institutions in the treatment of 82 children with ALL, 19 of whom were switched to the DFCI protocols while in continuing first remission with other treatment programs to complete a minimum of 2 years of maintenance therapy; the remaining 63 children, who had recently diagnosed disease, were consecutively enrolled in the DFCI protocols. Each child was assigned at diagnosis to a category of risk for relapse and treated accordingly. There were no remission induction failures or deaths due to induction therapy among the patients with newly diagnosed disease. There were no differences in total or event-free survival rates between the patients in Hamilton and those in London or between those whose protocols were switched and those who were treated from the beginning with the DFCI protocols. With a median follow-up interval of 144 weeks the total survival rate was 95% and the event-free survival rate 88%. For patients at standard risk of relapse the event-free survival rate was 100%, for those at high risk the rate was 82%, and for those at very high risk the rate was 67%. If infants (all of whom suffered a relapse) are excluded from the last category the rate was 89%. These results were achieved with moderate toxic effects (except for two deaths, one of which was due to a therapeutic misadventure) and suggest that the prospect for cure in children with ALL. may now approximate 80%, a degree of success that demands that consideration be given to reducing total therapy, at least for children with standard-risk disease. Further follow-up will determine whether these high event-free survival rates will stabilize and meet the criteria for cure.

Antineoplastic Combined Chemotherapy Protocols↗

Biochemical assays of hemoglobin in normal human erythroid clones.

Quantitation of small amounts (2-3 micrograms) of hemoglobin (Hb) was achieved by each of three spectrophotometric techniques. An assay employing benzidine base consistently underestimated Hb at this level and gave a wide scatter of results at higher values. The cyanmethemoglobin method was at the limit of its sensitivity and suffers from the disadvantage of having high optical densities in the blank samples. By contrast, pyridine hemochromogen can be detected accurately with 200 ng of Hb (equivalent of 6,000 mature erythrocytes), and the regression line with this technique virtually passes through the origin. Furthermore, the extinction coefficient of pyridine hemochromogen in the Soret band is 13.5-fold greater than that of cyanmethemoglobin. In normal human erythroid clones, generated in vitro from bone marrow cells, mean cell hemoglobin (MCH) values were determined after various intervals of culture. The MCH after 5, 7, 10, and 14 days were 11.8, 15.8, 26.6, and 34.4 pg, respectively, by the pyridine hemochromogen method. Reaction product was also identified in granulocyte-macrophage clones, presumably reflecting the content of other heme proteins such as catalase and cytochromes. Account must be taken of this non-Hb material in computing true MCH values for erythroid cells.

Bone Marrow Cells↗

Lithium and hydrocortisone interactions on cell growth and gene expression in human promyelocytic leukemia (HL60).

Lithium (Li) and hydrocortisone (HC) modify gene expression as well as stimulate human hematopoiesis in vivo and in vitro. The responses of blood-forming tissues, to these natural substances individually, are closely similar. However, clonogenic co-culture experiments, using normal human bone marrow cells, have revealed that the effects of Li and HC are not additive but rather mutually inhibitory. Studies of HL-60 cells in suspension indicate that growth of this human promyelocytic leukemic line is enhanced by HC at 10(-6) M, a "therapeutic" plasma concentration. This phenomenon is abrogated by the co-addition of Li at 3 x 10(-4) M, likewise a "therapeutic" plasma concentration. Neither substrate exerts any influence on the morphological or cytochemical features of differentiation which accompany exposure of HL-60 cells to dimethyl sulphoxide (DMSO), retinoic acid (RA), tetradecanoyl phorbol acetate (TPA) or sodium butyrate. In contrast, the expression of c-fms, a cellular proto-oncogene which codes for the CSF-1 (monocyte-macrophage colony-stimulating factor) surface membrane receptor, is modified by Li in the presence of the differentiation induction agents DMSO and RA which promote the development of mature granulocytes from HL-60 cells. These observations afford further insights into the humoral mechanisms which modulate the expression of genes involved in the regulation of hematopoiesis.

Cell Differentiation↗

Mineral homeostasis and bone mass in children treated for acute lymphoblastic leukemia.

Clinical observations of bone pain, abnormal gait, and unusual fractures during remission of leukemia led us to assess mineral status in a cohort of 16 children with acute lymphoblastic leukemia treated with intensive chemotherapy. During maintenance and 6 months after the completion of therapy, blood and urine were analyzed for calcium and magnesium and blood for osteocalcin, vitamin D, and parathyroid hormone. Bone mineral content and bone width of the distal one third of the radius of the nondominant arm was measured by single-photon absorptiometry. During therapy, mild ionic hypocalcemia (less than 1.19 mmol/L) and hypomagnesemia (less than 0.77 mmol/L) were demonstrated in 9 and 8 of 16 children, respectively; hypercalciuria (8/16) and hypomagnesiuria (12/16) were also observed. Plasma osteocalcin values correlated with plasma magnesium levels (r = 0.54; p less than 0.05). Oral magnesium supplements normalized plasma magnesium, calcium, and osteocalcin levels, all of which were normal at the postchemotherapy study. Plasma 1,25-dihydroxyvitamin D levels were nondetectable (less than 8 ng/ml) in 12 of 13 patients receiving therapy and in 7 of 14 patients not receiving therapy; alkaline phosphatase activity increased significantly after therapy (179 +/- 86 to 340 +/- 101 units/L), and parathyroid hormone levels were normal in both studies. Bone mineral content/bone width ratio was less than 1 SD below the mean for age- and sex-related population standards in 70% of patients. These data indicate that alterations in magnesium, calcium, and vitamin D metabolism in children treated for acute lymphoblastic leukemia may be instrumental in inducing or sustaining altered bone turnover during chemotherapy.

Antineoplastic Combined Chemotherapy Protocols↗

Acetylcholinesterase in the human erythron. I. Cytochemistry.

The successful demonstration and localisation of acetylcholinesterase (AChE), in cells by a cytochemical technique requires maximal expression of enzyme activity, minimal loss of AChE and precise, quantitative generation of reaction product at the actual site of the protein in vivo. These requirements are addressed in a standard technique that has been modified to avoid or optimise fixation and to exhibit enzyme activity under close-to-physiological conditions of osmolality, pH, and temperature. With these refinements and with the use of a variety of substrates and enzyme inhibitors of different specificities, true AChE was demonstrable on the membrane of erythrocytes and in the nucleus and cytoplasm of erythroblasts in bone marrow and of the constituent cells of erythroid clones in vitro. The activity in erythrocytes from umbilical cord blood was less than that in corresponding cells from the peripheral circulation of adults. AChE was observed also in human megakaryocytes and in leucocytes at all levels of differentiation, including the components of granulocyte-macrophage clones. Pseudocholinesterase was detected likewise across the spectrum of erythroid (and leucocyte) ontogeny, suggesting that these enzymes may exercise an important function in hematopoiesis.

Acetylcholinesterase↗

Acetylcholinesterase in the human erythron. II. Biochemical assay.

Acetylcholinesterase (AChE) is an integral erythrocyte membrane protein. A role for the enzyme in the developing human erythron is being explored. Assays of AchE by the standard Ellman technique overestimate the amount of enzyme by failing to account for the contribution of hemoglobin to the optical density of the reaction mixture. Furthermore, reliance on substrate selection alone for specificity is unsatisfactory. Incorporation of inhibitors of "true" AchE and of pseudocholinesterase confer greater ability to distinguish one enzyme from the other. In our experience, the inhibitor constant (Kl) for edrophonium, which is highly specific for AChE, is approximately 5 x 10(-5) M against adult human erythrocytes that contain significantly more total cholinesterase activity than do erythrocytes from umbilical cord blood. This consists of both "true" and "pseudo" enzyme, the former predominating and accounting for 0.75-1.65 (mean 1.02, median 0.87) femtomoles of substrate hydrolysed per min per cell in adult blood, with values of 0.15-1.04 (mean 0.71, median 0.73) obtained on cord blood. Moreover, the enzyme activity in neonatal erythrocytes has a rather different inhibitor profile from that of adult cells. AChE was also demonstrated in fresh (ALL) and cultured (K562 and HL60) human leukemic cells, as well as in primitive granulocyte-macrophage and erythroid cells cloned from normal human bone marrow. In the erythroid colonies the enzyme activity was 0-3.76 (mean 1.20, median 0.76) femtomoles per min per cell, apparently the first successful measurement of AChE in such cells.

Acetylcholinesterase↗

Interactions of lithium and hydrocortisone in vitro on normal human hematopoiesis.

Lithium salts and glucocorticosteroid hormones stimulate hematopoiesis in vitro and in vivo. In the former circumstance, the impact is demonstrable with concentrations of these substances which reflect physiological and pharmacological conditions. The evident therapeutic benefit of these effects, in patients who experience myelosuppression and pancytopenia with the use of cytotoxic chemotherapy for malignant disease, could be enhanced if the influences of lithium and steroids on blood cell formation were at least additive. However, the observations in this study suggest that these substances can be mutually inhibitory, with respect to hematopoiesis, and do not support the use of lithium and steroids in combination to alleviate iatrogenic reduction in bone marrow function.

Bone Marrow↗

The influence of corticosteroids on human erythropoiesis. An in vivo study.

Three groups of patients were studied to assess the effect of oral corticosteroid therapy on erythropoiesis in vivo as measured by changes in haemoglobin concentration (Hb) and red blood cell count (RBC). Fifteen patients with acute lymphoblastic leukaemia, who were in remission and receiving pulses of vincristine and prednisone during maintenance chemotherapy, showed no rise in Hb or RBC with steroid therapy. Likewise, 15 patients completing chemotherapy for ALL did not show a rise in Hb or RBC after stopping treatment. However, 14 children with acute immune thrombocytopenic purpura demonstrated a significant increase in Hb and RBC during a course of treatment with prednisone. These findings complement the results of in vitro studies, indicating that erythropoiesis in normal human bone marrow is stimulated by corticosteroid therapy.

Child↗