Search PubMed⌕ Search

Biomedical subjects

J A Stockman

Publications and source records attributed to J A Stockman.

At least 37 records · Page 2Linked to original sources

Practice-based research: opportunities and obstacles.

Renewed interest in practice-based research reflects growing realization of the limitations of research from a hospital perspective. Practice-based pediatric research promises to broaden the range and severity of conditions commonly studied, to enhance the study of the natural history of disease and of normal development, to provide normal controls and standards, and to facilitate recruitment of adequate sample sizes. Cohort, incidence, and health services research will be promoted by the development of patients registries. The Chicago area Pediatric Practice Research Group is a research consortium of 81 practitioners in 27 office practices. Formed in 1984, it receives logistic and financial support from Children's Memorial Hospital, with which it is affiliated. The Pediatric Practice Research Group has undertaken six studies, most with outside funding. During these studies, some unifying characteristics of practice-based research have emerged. These include the need to tailor study protocols to individual practice characteristics and routines and the critical role of office staff in the conduct of research. Features can be identified that make specific studies more or less intrusive into office functioning. It has proved feasible to obtain data of high quality and reproducibility despite geographically scattered data collection sites. This review of Pediatric Practice Research Group activities and experience is intended to open an exchange of ideas with others interested in practice-based research.

Humans↗

Anemia of prematurity. Current concepts in the issue of when to transfuse.

At no other time of life is the decision to transfuse potentially as difficult as in the newborn period. Superimposed upon complex "physiologic" changes in the ability to deliver and release oxygen are varying requirements among infants in terms of oxygen need. These are compounded by changes brought about as a direct consequence of frequent phlebotomy in the most ill of preterm infants. Despite the confusion overlying many of the changes occurring at this time of life, certain principles can be applied. Unlike that of the adult, an infant's ability to make oxygen available in response to a specific demand is almost as dependent upon the modifiers of oxygen uptake and release by hemoglobin as upon the hemoglobin concentration itself. These modifiers are constantly changing, sometimes in a predictable fashion, sometimes not. As discussed, some attention to the status of a particular infant's capability in providing oxygen relative to need will assist in the decision when to transfuse. If specific parameters of these assessments can not be determined, it may be necessary to proceed with transfusion based on the clinical presentation of an infant. With regard to the above, any infant sufficiently ill to require frequent blood sampling should have such blood losses replaced, certainly before ten percent of blood volume has been exceeded. This is particularly true in infants who are unable to maintain adequate arterial oxygen tensions with or without the use of supplemental inspired oxygen. At several weeks of age, when the clinical status of a preterm infant may have stabilized, transfusion may or may not be needed during the nadir of the anemia of prematurity. Infants who had been previously transfused or who had earlier received frequent simple transfusions should be able to tolerate lower levels of hemoglobin. Infants without compromised cardiopulmonary function and in whom no unusual metabolic needs exist are unlikely to be aided by transfusions when the hemoglobin concentration is greater than 10 to 11 g/dl. At lower levels of hemoglobin, simple calculations of "available oxygen" may be helpful when it is difficult to determine whether clinical signs and symptoms of anemia exist. Such signs and symptoms may include poor feeding, dyspnea, tachycardia, tachypnea, diminished activity, and pallor. Apnea has not unequivocably been shown to improve following transfusion. Clearly, our current concepts regarding indications for transfusion, even when based upon known principles of physiology, still represent an art form that is less than completely scientific.(ABSTRACT TRUNCATED AT 400 WORDS)

Anemia, Neonatal↗

Antibodies to human T-cell lymphotropic virus-I membrane antigens and inverted T4/T8 ratios in hemophiliacs.

Antibodies to the membrane antigens of human T-cell lymphotropic virus-I (anti-HTLV-MA) have been detected in patients with the acquired immune deficiency syndrome (AIDS) and in patients with hemophilia. The authors examined sera from 71 AIDS patients and 46 hemophiliac children for the presence of anti-HTLV-MA using an indirect membrane immunofluorescence assay with flow cytometry analysis. Thirty-seven of the 71 (52%) AIDS patients and 7 of the 46 (15%) hemophiliac patients had high titered anti-HTLV-MA, using a T-lymphoid cell line infected with the leukemia virus. None of the 78 control subjects had high titered antibody. All seven hemophiliac patients with elevated anti-HTLV-MA used Factor VIII concentrates, and all had inverted T-lymphocyte helper-suppressor (T4 [Leu-3]/T8 [Leu 2]) ratios. No correlations were found between inverted T4/T8 ratios and antibody to cytomegalovirus, Toxoplasma gondii, or hepatitis B. This work supports contentions that HTLV-like organisms cause AIDS and that these organisms are transmitted by blood products such as Factor VIII concentrate.

Acquired Immunodeficiency Syndrome↗

Weight gain: a response to transfusion in selected preterm infants.

A group of low-birth-weight infants with daily weight gains that were below the expected mean for postnatal age were examined to determine the effects of RBC transfusion on their weight gain. The mean hemoglobin concentration (+/- SD) in 13 infants (birth weight less than 1,500 g) prior to transfusion was 8.5 +/- 1.6 g/dL and 11.4 +/- 2.1 g/dL after transfusion. When a comparison was made between the daily weight gain for the week prior to transfusion with the week following transfusion, the mean daily weight gain (+/- SD) increased from 20.8 +/- 4.6 g to 28.0 +/- 6.3 g. Among the six infants with pretransfusion hemogloblin concentrations of less than 7.5 g/dL, the increase in daily weight gain was greatest (a rise from 22.6 +/- 4.0 g to 34.1 +/- 4.9 g). Improvements in weight gain were associated with a decrease in metabolic rates as determined by declines in oxygen consumption.

Age Factors↗

Anemia of prematurity: determinants of the erythropoietin response.

This study was undertaken to determine the factors that are important in determining the erythropoietin response in low-birth-weight infants during the period of so-called anemia of prematurity. In the first weeks of life oxygen consumption in a group of 21 infants gradually increased as hemoglobin level fell. The magnitude of the erythropoietin response inversely varied with the central venous oxygen tension (P-vO2) (r = -0.55, P less than 0.001). When the P-vO2 declined to less than 30 torr, erythropoietin values were uniformly increased above the "normal" range (defined as the values associated with P-vO2 greater than 38 torr). Erythropoietin values varied inversely with hemoglobin but in general did not exceed the values observed for normal adult men. The erythropoietin values in the infants were remarkably lower at any given hemoglobin level when compared with those of older children with anemia resulting from bone marrow failure. In general, elevations of erythropoietin were seen when the hemoglobin concentration declined to less than 10.0 gm/dl. Change in heart rate did not appear to be a reliable indicator of the presence of anemia; rather, it correlated best with oxygen consumption.

Adult↗

Toxocara antigen and mitogen-induced lymphocyte blastogenesis for diagnosis of visceral larva migrans: clinical and experimental findings in macaques and human beings.

Peripheral lymphocytes from macaques inoculated with Toxocara canis and from children with serologically confirmed visceral larva migrans (VLM) were assayed for blastogenic responses using Toxocara antigen and standard mitogens. Macaques were given single or multiple larval infections. Lymphocyte responses of inoculated macaques were compared with responses from noninoculated macaques. Similarly, lymphocyte responses from 2 serologically confirmed human Toxocara VLM patients were compared with that of 2 healthy human controls. Mitogen responses of the macaques with multiple infections were higher than those with single infections or no infection, but these differences were not significant. Statistically greater (P less than 0.05) Toxocara antigen-induced blastogenesis was observed for both groups of inoculated macaques and for each VLM patient. However, the degree of stimulation was low.

Animals↗

Chronic neutropenia: diagnostic approach and prognosis.

Chronic neutropenia is a term used to describe a group of disorders characterized by a persistent neutrophil count of less than 1500 cells/microliters. We studied seven children and three sets of parents. We separated patients into a group with good prognosis and a group at higher risk of infection by using a combination of tests, including bone marrow aspiration and biopsy, steroid stimulation of bone marrow reserve, and in vitro CFU-GM and CSA assays. Children with a normal number of myeloid elements in their bone marrow and a normal bone marrow response to steroid stimulation had a benign course. CFU-GM and CSA assays helped to classify these children's neutropenia when their bone marrow had decreased numbers of myeloid elements. Family studies in three children were consistent with an inherited neutropenia, even when their parents were hematologically normal.

Adult↗

Preleukemic states in children with acute lymphoblastic leukemia.

Two cases are reported of childhood acute lymphoblastic leukemia presenting with preleukemic states and 13 other cases in the literature are reviewed. Hypoplastic anemias, which transiently resolved spontaneously or with steroid therapy, were seen most commonly. Acquired hypoplastic anemias, even when associated with spontaneous resolution, may at times represent a preleukemic state.

Anemia, Aplastic↗

Red cell transfusion in the newborn. Indications and unique blood banking needs.

The nursery presents unique problems for the physician caring for ill newborn infants. The indications for transfusion and the blood banking techniques to provide for these needs have changed significantly in recent years. The decision to transfuse must be based on an understanding of what is known to normally occur with respect to the postnatal decline in hemoglobin and the adaptive mechanisms which exist at this age. Exchange transfusion by increasing oxygen availability at any hemoglobin level may result in a greater than expected decline in hemoglobin. Several blood banking procedures have been developed to provide for the transfusion requirements of the neonate. The walking donor system remains controversial and has created opposition by the American Association of Blood Banks. The use of triple, quadruple, and "cow' pack systems has allowed a greater versatility and better utilization. The concept of frozen red cell transfusions has been extended to the nursery setting with the introduction of "pedi-paks.' These techniques have clearly diminished the risks of transfusion in the neonatal period.

Blood Banks↗

HLA antigens and childhood acute lymphocytic leukaemia.

HLA-A and -B antigens were determined for 94 children with acute lymphocytic leukaemia (ALL) and for 376 normal controls. Sixty-four of these 94 patients were typed for lymphocyte surface markers and 59 were defined as 'null cell' ALL. There was no difference in the distribution of the HLA-A or -B locus antigens between the control group and the entire group of patients with ALL or the 'null cell' subgroup. Patients with HLA-A9 determinants had a significant increase in early, first remission duration compared to patients without HLA-A9. This was particularly evident in the 'null cell' ALL subgroup. In addition, HLA-A9 appeared to be an independent factor affecting the length of first remission since there was no correlation between known prognostic factors such as patient age, sex or WBC and the presence or absence of the HLA-A9 antigen. Survival for the first 12-18 months was also greater in the HLA-A9 group than in the non-HLA-A9 population. Thus, the presence of HLA-A9 appears to be associated with some protective effect among patients with ALL.

Adolescent↗

Transfusion nomogram: an application of physiology to clinical decisions regarding the use of blood.

A nomogram has been prepared that depicts relationships between cardiac output (Q), oxygen consumption (Vo2), hemoglobin concentration (Hb), the position of the oxygen-hemoglobin dissociation curve, the oxygen saturation of arterial blood (SaO2), and the partial pressure of oxygen in the mixed venous blood (PVO2). Examples are provided to illustrate how this nomogram may be employed to facilitate decisions regarding the need for blood transfusions in patients in whom oxygen delivery may be impaired.

Blood Transfusion↗