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Biomedical subjects

S McIntosh

Publications and source records attributed to S McIntosh.

At least 37 records · Page 2Linked to original sources
PubMed1993

Determination of inorganic arsenic and its organic metabolites in urine by flow-injection hydride generation atomic absorption spectrometry.

A method has been developed for the determination of inorganic arsenic [As(III) and As(V)] and its organic metabolites (monomethylarsenic and dimethylarsenic) in urine by flow-injection hydride generation atomic absorption spectrometry. The nontoxic seafood-derived arsenobetaine and arsenocholine species were first separated by a solid-phase extraction procedure. The remaining sample was digested with a mixture of nitric and sulfuric acids and potassium dichromate, followed by attack with hydrogen peroxide. The resulting As(V) was reduced to As(III) with potassium iodide in hydrochloric acid before injection into the flow-injection manifold. The percentage analytical recoveries (mean +/- 95% confidence interval) of various arsenic species added to a urine specimen at 250 micrograms/L were 108 +/- 2, 112 +/- 11, 104 +/- 7, and 95 +/- 5 for As(III), As(V), monomethylarsenic, and dimethylarsenic, respectively. For the determination of arsenic in Standard Reference Material 2670 (toxic metals in human urine), results agreed with the certified value (480 +/- 100 micrograms/L). Analyses of samples for the Centre de Toxicologie du Quebec, containing seafood-derived species, demonstrated the viability of the separation procedure. Detection limits were between 0.1 and 0.2 microgram/L in the solution injected into the manifold, and precision at 10 micrograms/L was between 2% and 3% (CV). These preliminary results show that the method might be applicable to determinations of arsenic in a range of clinical urine specimens.

Arsenic↗
PubMed1991

Fibrinogen Ledyard (A alpha Arg16----Cys): biochemical and physiologic characterization.

Fibrinogen Ledyard was discovered in a 10-year-old boy with a mild bleeding history. His father had the same defect and a bleeding history after surgery. Both patients were heterozygous. The plasma fibrinogen concentration was normal immunologically (335 mg/dL) and very low functionally (52 mg/dL). Purified fibrinogen Ledyard had a prolonged polymerization, which was somewhat corrected by addition of Ca2+ ions. High performance liquid chromatography (HPLC) analyses of the fibrinopeptides released by thrombin showed 1 mol of fibrinopeptide A (FPA) and 2 mol of fibrinopeptide B (FPB) released per mole of fibrinogen Ledyard. Steady-state kinetic parameters were evaluated for release of FPA by thrombin. When the concentration of fibrinogen Ledyard was corrected to 50% of total protein, because only 50% of fibrinogen Ledyard can release FPA, the kinetic constants were similar to those of control fibrinogen (Km = 7.5 mumol/L for A alpha chain, kcat = 54 s-1). This finding indicates that the cleavage site of the A alpha chain in these abnormal molecules may not interact with the catalytic site of thrombin. The three chains of fibrinogen Ledyard were isolated on reverse-phase C4-HPLC. The sequence of the amino terminus of A alpha chain showed that Arg in position 16 was replaced by Cys in the abnormal molecules. Approximately half of fibrinogen Ledyard (52%) was clotted by reptilase, suggesting that fibrinogen Ledyard may consist of 50% normal homodimers (A alpha Arg16 . A alpha Arg16) and 50% abnormal homodimers (A alpha Cys16 . A alpha Cys16). Abnormal molecules could form disulfide bond between the A alpha Cys16 residues. Thus, the abnormal molecules have a different structure that does not bind to thrombin. Probably the abnormality of polymerization of fibrinogen Ledyard results from the interaction of the abnormal molecules with normal fibrin monomers, so that the growth of fibrin protofibrils is inhibited. This abnormal fibrinogen supports adenosine diphosphate-induced platelet aggregation in a normal manner.

Amino Acid Sequence↗
PubMed1991

Development and evaluation of the revised Alcohol Evaluation Instrument.

This study reports on the development of a revised version of the Alcohol Evaluation Instrument (ALCEVAL-R). Items in the four major areas of the ALCEVAL-R were factor analyzed separately and relationships among factors were examined. Results suggest that the ALCEVAL-R measures clinically meaningful aspects of the alcoholic patient's occupational and social status, and reveals important dimensions of alcohol consumption and of the personal and social consequences of alcohol abuse.

Alcohol Drinking↗
PubMed1990

Elective splenopexy for wandering spleen.

The diagnosis of wandering spleen is usually made at the time of operation owing to symptoms caused by torsion of the spleen. Splenectomy has been performed in almost all of the reported cases. A 6-year-old girl presented with intermittent abdominal pain and a mobile abdominal mass. The diagnosis of wandering spleen was confirmed by computerized tomography. Elective splenopexy was performed by securing the spleen in an extraperitoneal pocket.

Child↗
PubMed1986

Cerebrospinal fluid monoamine precursor and metabolite levels in children treated for leukemia: age and sex effects and individual variability.

Lumbar cerebrospinal fluid (CSF) was obtained from children during and following treatment for acute lymphoblastic leukemia (ALL). One hundred ninety-two CSF samples from 50 subjects, which were selected to minimize the effects of the disease and its treatment (i.e., to approach "normality" as closely as possible), were analyzed for the monoamine precursors tyrosine (Tyr) and tryptophan (Trp) and the metabolites homovanillic acid (HVA) and 5-hydroxyindoleacetic acid (5-HIAA). Levels of HVA (p less than 0.0001), 5-HIAA (p less than 0.002), and Tyr (p less than 0.05) decreased with age from 3 to 17 years. Significant correlations were observed between the acid metabolites HVA and 5-HIAA (r = 0.79) and between the amino acid precursors Tyr and Trp (r = 0.71). Within individuals, levels of all four compounds were relatively stable over time, with total mean coefficient of variation ranging from 20% to 25%. No significant sex differences for CSF levels of HVA, 5-HIAA, Tyr, or Trp were found. Assessment of CSF monoamine precursors and metabolites in children treated for ALL may provide a method for understanding the chronic effect of CNS trauma on the ontogeny of monoamine systems.

Adolescent↗
PubMed1986

Diagnostic problems in cerebrospinal fluid of children with lymphoid malignancies.

The interpretation of small numbers of lymphoblasts or of nonspecific pleocytosis in the cerebrospinal fluid (CSF) of children with lymphoid malignancies is difficult. In this prospective study of 204 patients, 15 had white cell chamber counts of less than or equal to 10 cells/microliter, with one or more blasts on a cytocentrifuged smear. Only 3/15 subsequently developed meningeal leukemia, and 4/15 remain in continuous complete remission. Among 53 patients with a chamber count greater than 10 WBC/microliter and no blasts, pleocytosis was associated with central nervous system (CNS) prophylaxis in half. Less common were viral syndromes, immune recovery, subsequent meningeal leukemia, active hematologic leukemia, the somnolence syndrome, leukoencephalopathy, or reaction to a previous traumatic lumbar puncture.

Adolescent↗
PubMed1985

Adjuvant chemotherapy for medulloblastoma.

The use of adjuvant chemotherapy for cerebellar medulloblastoma is controversial. Twenty-one children and adolescents were treated with adjuvant low-dose cyclophosphamide and vincristine following surgery and radiotherapy. With a mean observation period of 6 years, the disease-free survival is 81%.

Adolescent↗
PubMed1985

Endodermal sinus tumor of the infant vagina.

A case of endodermal sinus tumor of the infant vagina is reported with long-term survival after successful therapy by surgery, chemotherapy, and radiation. The previous 26 reported cases are reviewed and the problems of therapy and long-term management are discussed. Therapy of these tumors should be monitored by alpha-fetoprotein radioimmunoassay.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1981

Immunoregulatory abnormalities in children with thrombocytopenic purpura.

Twenty-eight children with idiopathic thrombocytopenia and 51 members of their immediate families were studied for immunologic function and expression of autoimmune phenomena and disease. Among patients with active ITP, 64% had defective immunoregulatory lymphocytes. The majority of patients (23/28) and family members had one or more immunologic abnormalities, including autoantibodies, other autoimmune disorders, and abnormalities in complement, immunoglobulins, or regulatory T lymphocytes. These data suggest that a genetic predisposition to autoimmunity is present in the majority of children with ITP.

Adolescent↗
PubMed1981

Spontaneously acquired Factor IX inhibitors in childhood.

Two previously healthy children, ages 8 months and 35 months, developed spontaneous inhibitors to Factor IX. Brief illnesses of presumed viral origin preceeded hemorrhagic symptoms in both children. Cutaneous ecchymoses and traumatic soft tissue hemorrhage were the predominant clinical features in each case. Bleeding symptoms persisted for less than 3 days and laboratory evidence of Factor IX inhibition resolved within 3 weeks. One child required treatment with fresh frozen plasma and packed red blood cell transfusions. The other child received corticosteroid therapy. Given the transient nature of acquired Factor IX inhibitors in the nonhemophilic child, a conservative approach toward therapy is recommended unless life-threatening complications supervene.

Blood Transfusion↗
PubMed1980

Relationship of SV40 T-antigen expression in vitro to disorders of bone marrow function.

Skin fibroblasts from patients with a variety of hematologic disorders were infected with SV40 virus in vitro in attempts to discover the reason for increased susceptibility of Fanconi anemia cells to this transforming virus. The proportion of skin fibroblasts expressing SV40 T-antigen by immunofluorescent methods was elevated in 12 patients with Fanconi anemia and in seven of nine obligate heterozygous relatives. Elevated expression was also observed in three patients with other hematological disorders at high risk of acute non-lymphocytic leukemia, but was not apparent in seven sporadic aplastic anemia patients or four of their relatives. T-antigen expression was elevated in about one-half of patients with thrombocytopenia-absent radius syndrome and related conditions, with familial aplastic anemia, and in their normal relatives. In the conditions under study, elevated T-antigen expression seemed clearly correlated with predisposition to leukemia, which may be genetically determined, but it was not associated with cytogenetic or anemic manifestations.

Anemia↗
PubMed1980

Fever in young children with sickle cell disease.

Bacterial septicemia and meningitis are major causes of death in young children with sickle cell anemia. We report a prospective study of 182 episodes of fever among 22 children with sickle cell diseases identified at birth. The majority of patients with fever exceeding 39.5 degrees C were treated with antibiotics intravenously until results of blood cultures were known. Infectious diseases were documented in 38% of all febrile events. Six episodes of bacterial septicemia, two associated with meningitis, were successfully treated with no mortality or residual morbidity. These data form the basis of suggestions for management of the young child with sickle cell disease and fever.

Anemia, Sickle Cell↗