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Biomedical subjects

R D Barr

Publications and source records attributed to R D Barr.

At least 19 recordsLinked to original sources
PubMed1992

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

The primary purpose of this study was to determine the therapeutic efficacy of a protocol of treatment for acute lymphoblastic leukemia (ALL) in children. A prospective approach was adopted with an inception cohort of patients. Outcome measures were assessed on December 31, 1990. The study was conducted at two tertiary care centres (pediatric oncology programs) in Ontario, Canada. All children with ALL were eligible for study and consecutive recruitment took place between May 1984 and July 1987. They were classified at diagnosis into one of three categories for risk of relapse according to standardized criteria. Thirty-nine children were designated as having standard risk (SR), 31 as having high risk (HR), and 12 as having very high risk (VHR) disease. All patients are included in the analysis. Treatment was administered according to risk category-specific chemotherapy protocols, the details of which have been published. A distinguishing feature of these strategies is the intensive use of intramuscular L-asparaginase. Patients remained on these regimens for 2 years or until relapse or toxic death (events) ensued. Total and event-free survival data were determined by life-table analysis (Kaplan-Meier plots). With a minimum interval from diagnosis of 186 weeks and a median interval exceeding 5 years, the cumulative proportion of the entire cohort (C) surviving is 85% [95% confidence interval (CI), 77-93%]. For the respective risk groups, the corresponding proportions are SR 94% (95% CI, 87-100%), HR 74% (95% CI, 59-89%), and VHR 81% (95% CI, 59-100%).(ABSTRACT TRUNCATED AT 250 WORDS)

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1992

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↗
PubMed1992

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↗
PubMed1991

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↗
PubMed1991

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↗
PubMed1979

The role of the lymphocyte in haemopoiesis.

According to current dogma, circulating blood cells are all derived from the same progenitor, which therefore must be both pluripotent and capable of prolific self-replication. In the irradiated mouse, such haemopoietic stem cells (HSC) give rise to splenic colonies, and thus are designated as CFU-S (colony forming units-spleen). Definitive identification of a similar entity in man so far has proved elusive. However, primitive unipotent cells, committed to development along a single pathway, can be detected in human blood-forming tissues under appropriate culture conditions. Operationally defined as CFU-E (erythrocyte), CFU-GM (granulocyte/macrophage) etc., the ontogenetic relationships of these cells to each other and to the HSC have been the objects of exhaustive study. A population of lymphocytes, classed as "null" cells, do not exhibit the surface membrane markers which characterize commitment to differentiation in the thymus-dependent (T-cell) or bursa- equivalent (B cell) lineages. Accumulating evidence points to the null lymphocyte as a potential precursor of haemopoietic tissue. In bone marrow, the activity of terminal deoxynucleotidyl transferase (TdT) is concentrated in null cells, but the relevance of this unique enzyme to lymphocytic differentiation remains uncertain. Nevertheless, it appears that the functional heterogeneity, expressed within the family of lymphocytes, extends to haemopoiesis. The roles of various lymphocyte populations, in the generation and functional control of blood-forming tissue, are examined in this review.

Animals↗
PubMed1979

Influence of physical factors on morphological features of mononuclear cells in human blood. Lymphocyte-monocyte interconversion.

The recovery of monocytes, following density sedimentation of human peripheral blood, was previously observed to be greater than 100%. An explanation was sought in the present study. No evidence for erroneous estimation of these cells was found. Rather, the data suggest that lymphocytes may take on the appearance of monocytes as a consequence of cytocentrifugation. This phenomenon does not appear to be influenced by the osmolality or viscosity of the suspending medium, nor by the process of sedimentation. Moreover, polymorphonuclear leukocytes do not seem to participate in the process of transformation, which may depend instead on the transfer of cytoplasm from monocytes to lymphocytes.

Blood Sedimentation↗
PubMed1978

Dysfibrinogenaemia and liver cell growth.

From the evidence presented, it is proposed that 'dysfibrinogenaemia' represents the production of normal fetal fibrinogen by rapidly proliferating liver cells in both regenerating and neoplastic tissue. Prolongation of the reptilase clotting time, which was formerly believed to reflect dysfibrinogenaemia, may be rather the result of hepatocytic death.

Batroxobin↗
PubMed1977

Portal vein thrombosis in adults.

Idiopathic thrombotic occlusion of the extrahepatic portal vein is one of the commonest causes of portal hypertension in adult Blacks. The condition occurs more frequently in men and may be accompanied by evidence of minor functional impairment of the liver. Associated pancytopenia is quantitatively related to the degree of splenomegaly. Assessment of a spectrum of variables of blood coagulation and fibrinolysis, while failing to shed light on the possible pathogenesis, does suggest a rational basis for thrombolytic therapy.

Adolescent↗