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Biomedical subjects

P A Lane

Publications and source records attributed to P A Lane.

At least 19 recordsLinked to original sources
PubMed1997

An evaluation of two primary care interventions for alcohol abuse among Mexican-American patients.

AIMS: This study examined the effects of two primary care interventions (a physician intervention and a clinic-based psychoeducational group) on drinking patterns, psychosocial problems and blood test results (MCV, GGT, SGOT and SGPT). DESIGN: Subjects were randomized into one of four treatment groups: physician intervention, psychoeducation, both interventions, or no intervention. Follow-up data were collected at 12 and 18 months. SETTING: Subjects were recruited from a family practice outpatient clinic managed by a public hospital. PARTICIPANTS: Included 175 Mexican-American female and male primary care patients who screened positive for alcohol abuse or dependence. These patients were not seeking help for alcohol problems. INTERVENTIONS: Included a brief physician intervention and a 6-week patient psychoeducational group. MEASUREMENTS: The Diagnostic Interview Schedule assessed subjects for alcohol abuse; the Addiction Severity Index measured alcohol-related problems, including psychosocial issues. FINDINGS: All four treatment groups demonstrated significant improvement over time, with few differences between intervention and control groups. CONCLUSIONS: Assessment can be confounded with brief interventions; future investigators should use non-assessed control groups.

Adolescent↗
PubMed1996

Practical guide to the diagnosis of thalassemia. Council of Regional Networks for Genetic Services (CORN).

Thalassemias occur in individuals of all ethnic backgrounds and are among the most common genetic diseases worldwide. The diagnosis of thalassemia can easily be part of primary medical practice. Here we outline a practical approach to the detection of thalassemias in three common clinical settings. The first involves any patient with a low mean corpuscular volume (MCV) with or without anemia. The second is a neonatal screening result indicating possible presence of thalassemia. Finally, evaluation for thalassemia should be considered in the context of family planning or pregnancy in patients whose ethnicity indicates origin from high risk geographic areas. We also review the various types of the thalassemia syndromes and provide an overview of general therapeutic considerations.

Family Planning Services↗
PubMed1996

Sickle cell disease.

The identification of genetic mutation that causes sickle cell disease 35 years ago has not yet led to a widely applicable, specific therapy that corrects the underlying abnormality of hemoglobin. Nevertheless, recent progress in understanding the pathophysiology and natural history of sickling disorders has led directly to important prophylactic and supportive therapies that have markedly reduced morbidity and prolonged life expectancy. This is particularly true for manifestations of sickle cell disease that result from damage to the spleen, lungs, and brain. New strategies for specific therapy, including expanded use of chronic transfusions, bone marrow transplantation, and hydroxyurea, now offer hope for prevention of many or all of the hemolytic and vaso-occlusive manifestations of sickle cell disease.

Anemia, Sickle Cell↗
PubMed1996

Thrombo-embolic disease after splenectomy for hereditary stomatocytosis.

Nine cases of hereditary stomatocytosis (HSt) are presented which show documented thrombotic complications after splenectomy. In three cases, patients became severely ill with pulmonary hypertension and a fourth developed portal hypertension. One unsplenectomized affected adult relative had suspected but unconfirmed thrombotic pathology; the six other affected unsplenectomized adults did not. Since splenectomy is of only limited therapeutic benefit in stomatocytosis, it should not be performed without careful consideration. A tendency to iron overload, even without hypertransfusion and irrespective of splenectomy, is evident in many of these patients.

Adult↗
PubMed1995

Functional asplenia in hemoglobin SC disease.

The incidence of functional asplenia in sickle-hemoglobin C (SC) disease has not been defined, and the use of prophylactic penicillin to prevent life-threatening septicemia in this disorder is controversial. The percentage of red blood cells with pits (pit count) is a reliable assay of splenic function in other disorders but has not been validated in hemoglobin SC disease. To address these issues, we conducted a prospective, multicenter study of splenic function in persons with hemoglobin SC disease. Baseline clinical data were recorded, and red blood cell pit counts were performed on 201 subjects, aged 6 months to 90 years, with hemoglobin SC; 43 subjects underwent radionuclide liver-spleen scanning. Pit counts greater than 20% were associated with functional asplenia as assessed by liver-spleen scan, whereas pit counts less than 20% were found in subjects with preserved splenic function. Pit counts greater than 20% were present in 0 of 59 subjects (0%) less than 4 years of age, in 19 of 86 subjects (22%) 4 to 12 years of age, and in 25 of 56 subjects (45%) greater than 12 years of age. Other subjects with hemoglobin SC, who had previously undergone surgical splenectomy, had higher pit counts (59.7% +/- 9.5%) than splenectomized subjects without hemoglobinopathy (38.5% +/- 8.8%) or with sickle cell anemia (20.5% +/- 1.9%; P < .001). Two subjects with hemoglobin SC disease (not splenectomized), ages 14 and 15 years, with pit counts of 40.3% and 41.7% died from pneumococcal septicemia. These data indicate that functional asplenia occurs in many patients with hemoglobin SC disease, but its development is usually delayed until after 4 years of age. The pit count is a reliable measure of splenic function in hemoglobin SC disease, but values indicative of functional asplenia (> 20% in our laboratory) are higher than in other disorders. The routine administration of prophylactic penicillin to infants and young children with hemoglobin SC disease may not be necessary.

Adolescent↗
PubMed1995

The spleen in children.

The spleen contributes importantly to the normal and pathologic removal of blood cells from the circulation and to defense against infection with encapsulated bacteria. Surgical splenectomy provides efficacious treatment for a number of pediatric disorders but is associated with perioperative morbidity and a life-long risk of overwhelming infection. Alternatives to conventional splenectomy include laparoscopic splenectomy, partial splenectomy, partial splenic embolization, and autologous splenic transplantation. Sickle cell disease is the most common cause of functional asplenia in children. Asplenia develops during infancy in many infants with sickle cell anemia, and prophylactic penicillin markedly reduces mortality from pneumococcal infection. In contrast, recent evidence suggests that children with sickle-hemoglobin C disease do not develop functional asplenia before 3 to 4 years of age and thus may not benefit from penicillin prophylaxis. Recommendations for the treatment of asplenic patients include pneumococcal, Haemophilus influenzae type b, and meningococcal immunizations, antimicrobial prophylaxis for selected patients, and prompt evaluation and aggressive treatment of acute febrile illness.

Child↗
PubMed1994

Erythrocyte membrane vesicles and irreversibly sickled cells bind protein S.

Plasma levels of free protein S, a vitamin K-dependent anticoagulant, are decreased in persons with sickle cell anemia, but the etiology of the low levels is unknown. Protein S binds to phosphatidylserine-containing phospholipids in a calcium-dependent manner. Other studies have indicated that phosphatidylserine may be abnormally present on the outer surface of the membrane lipid bilayer of sickle cells and of the spectrin-depleted vesicles they shed in vivo. We studied the binding of purified, radiolabeled protein S to spectrin-depleted erythrocyte membrane vesicles and to density-separated fractions of sickle and normal erythrocytes. Calcium-dependent binding of protein S occurred with vesicles and with well-aerated dense irreversibly sickled cells, but not with well-aerated sickle discocytes or with normal erythrocytes. These data provide further evidence that phosphatidylserine is abnormally present on the outer surface of spectrin-depleted vesicles and of irreversibly sickled cells. In addition, protein S binding to such sickle membranes in vivo may be responsible, in part, for the decreased levels of free protein S in sickle cell plasma.

Anemia, Sickle Cell↗
PubMed1994

Acute multiorgan failure syndrome: a potentially catastrophic complication of severe sickle cell pain episodes.

The purpose of this report is to characterize the acute multiorgan failure syndrome that complicates some episodes of sickle pain. A retrospective chart review was used to identify episodes of sickle pain complicated by the acute failure of at least two of three organs: lung, liver, or kidney. The defining criteria of organ failure were established, and the clinical characteristics, laboratory values, treatment methods, and outcomes were noted in episodes that met the criteria. Seventeen episodes of acute multiorgan failure were identified in 14 patients, 10 with sickle cell anemia and 4 with hemoglobin SC disease. Most episodes occurred during a pain event that was unusually severe for the patient. The onset of organ failure was associated with fever, rapid fall in hemoglobin level and platelet count, nonfocal encephalopathy, and rhabdomyolysis. Bacterial cultures were negative in all but four episodes. Aggressive transfusion therapy was associated with survival and with rapid recovery of organ function in all but one episode. The syndrome developed in patients who had previously exhibited relatively mild disease with little evidence of chronic organ damage and relatively high hemoglobin values in steady state. Acute multiorgan failure syndrome is a severe, life-threatening complication of pain episodes in patients with otherwise mild sickle cell disease. The syndrome appears to be reversed with prompt, aggressive transfusion therapy. High baseline hemoglobin levels may represent a predisposing factor.

Acute Disease↗
PubMed1994

Fatal pneumococcal septicemia in hemoglobin SC disease.

We retrospectively examined the medical and autopsy records of seven previously unpublished cases of fatal pneumococcal septicemia in children with hemoglobin SC disease. The earliest death occurred in a 1-year-old child who had congenital heart disease with cyanosis; the other children were aged 3 1/2 to 15 years. Only one child had received pneumococcal vaccine or prophylactic penicillin therapy. All seven children had an acute febrile illness and rapid clinical deterioration despite parenterally administered antibiotic therapy and intensive medical support. Erythrocyte pit counts in two patients were 40.3% and 41.7%, respectively (normal, < or = 3.6%). Autopsy data from five cases showed marked splenic congestion without infarction in five, splenomegaly in four, and bilateral adrenal hemorrhage in three. These cases illustrate that functional asplenia predisposes some children with hemoglobin SC disease to the development of fatal septicemia after the age of 3 years. We conclude that pneumococcal vaccine should be administered to all children with hemoglobin SC disease and that acute febrile illnesses should be investigated promptly for the possibility of septicemia. The routine use of prophylactic penicillin therapy in infants and children with hemoglobin SC disease remains controversial.

Adolescent↗
PubMed1993

Hemoglobin D Ibadan-beta zero thalassemia: detection by neonatal screening and confirmation by electrospray-ionization mass spectrometry.

We describe an infant with hemoglobin D Ibadan-beta zero thalassemia whose hemoglobinopathy was initially detected by neonatal screening. This previously undescribed condition was confirmed by family studies and by globin chain analysis by mass spectrometric techniques. The case illustrates the importance to neonatal screening programs of confirmatory testing and of linkage with reference laboratories capable of globin chain analysis. Hematologic studies at 36 months of age suggested that the presence of hemoglobin D Ibadan had no deleterious effect on this child with heterozygous beta zero thalassemia.

Globins↗
PubMed1993

Sickle hemoglobinopathies.

Neonatal screening for hemoglobinopathies, coupled with comprehensive medical care that includes parental education, prophylactic penicillin, and immunizations, has markedly reduced mortality from sickle hemoglobinopathies during infancy and early childhood. However, despite an increased knowledge of pathophysiology, current therapy does little to prevent acute, noninfectious complications such as anemic crises, pain events, or strokes; nor does it reliably prevent or delay the development of chronic organ damage. Recent publications have increased our understanding of factors that contribute to the clinical heterogeneity of sickle hemoglobinopathies, improved modestly our ability to identify and treat acute complications, and provided real hope for the development of potentially curative therapies. Prospective therapeutic trials of hydroxyurea and of bone marrow transplantation have recently begun.

Anemia, Hemolytic↗
PubMed1993

The development and characterization of an eluted stain assay (ESTA) for the insulin-like growth factors.

An Eluted Stain Assay System (ESTA) has been adapted for the bioassay of the insulin-like growth factors, IGF-I and IGF-II. This ESTA is based on the Fischer Rat Thyroid cell line FRTL-5 which was grown as uniform, adherent microcultures on 96-well microtitre plates. The cells were stimulated with the growth factors for 48 h in hormone and serum free conditions. Responses were determined by the addition of the tetrazolium salt MTT which was reduced to a purple formazan product in a dose related manner. This was directly eluted from the cells and measured with a microtitre plate reader. The signal generated was solely dependent on metabolic activation of the cells, since no increase in cell numbers was detected during the bioassay. The advantages of using this method are its sensitivity, precision, specificity, rapidity and high sample throughout. This bioassay, which is based on a colorimetric method, is technically convenient compared with other systems including the earlier cytochemical bioassays and the radioisotopic methods. We have demonstrated that this MTT ESTA provides a useful method for the study of complex interactions between IGF-I and IGF-II and their related binding proteins and that IGF bioactivity in serum may also be investigated using this ESTA bioassay.

Adult↗
PubMed1993

Cardiopulmonary function in men with sickle cell trait who reside at moderately high altitude.

Sickle cell trait has been associated with an unexplained increased risk of sudden death during military basic training. Previous studies of cardiopulmonary function in persons with sickle cell trait at sea level or after brief exposure to moderately high altitude have not shown significant abnormalities. To determine whether cardiopulmonary function is impaired in men with sickle cell trait who chronically reside at moderately high altitude, we prospectively studied 17 men with sickle cell trait and 25 men with normal hemoglobin. All subjects had resided at > or = 1609 m above sea level for at least 10 years. Resting pulmonary function and cardiopulmonary performance during exercise to exhaustion were evaluated. No statistically significant differences were observed between subjects with sickle cell trait and controls for any of the resting pulmonary function variables measured. All parameters of exercise performance were not statistically different between the groups. Increasing age was associated with a similar decrease in work capacity and oxygen consumption in both groups. Electrocardiogram findings were not statistically different between groups. We conclude that chronic exposure to moderately high altitude does not impair cardiopulmonary function in men with sickle cell trait.

Adult↗
PubMed1993

Iron chelation by deferoxamine in sickle cell patients with severe transfusion-induced hemosiderosis: a randomized, double-blind study of the dose-response relationship.

Transfusion-induced hemosiderosis is a serious and potentially life-threatening complication for some patients with sickle cell anemia. The use of high-dose intravenous deferoxamine (DFO) has become widespread in spite of a paucity of published data on safety and efficacy. We report a randomized double-blind study of the dose-response relationship of intravenous DFO in six subjects with sickle cell anemia and severe transfusion-induced hemosiderosis (serum ferritin 4100 to 14,176 ng/ml). Each subject received three different doses of intravenous DFO for 3 days each while consuming a constant diet. Total iron excretion (urine and fecal) was 91% greater at 180 mg/kg/day DFO than at 60 mg/kg/day DFO, and fecal iron excretion became a relatively larger proportion of total excretion at higher doses. Subsequent treatment for 3 months with 150 mg/kg/day DFO caused a 33% to 60% reduction in serum ferritin and demonstrable improvement in hepatic function in all patients. No toxicity was encountered, but DFO at 180 mg/kg/day was associated with a significant increase in fecal zinc excretion when compared with that observed at lower doses.

Adolescent↗
PubMed1992

Schwann cell endocytosis: a role in nerve regeneration?

Schwann cell plasma membrane vesicles have been shown to increase in numerical density after nerve injury but their function is unclear. In this study, ultrastructural tracers were micro-injected in vivo into crushed rat sciatic nerves after various time intervals to ascertain whether plasma membrane vesicles of Schwann cells are involved in the uptake and utilization of molecules from the endoneurium during axonal regeneration and remyelination. Horseradish peroxidase (HRP), a tracer of fluid-phase endocytosis, was taken up by macrophages and fibroblasts but remained external to Schwann cells throughout the study. After 14-16 days of crush injury, HRP was present within vessel lumina and in cytoplasmic vesicles of pericytes and vascular endothelia. Low-density lipoprotein-gold, which is primarily internalized by receptor-mediated endocytosis, and bovine serum albumin-gold, proposed as a tracer for fluid-phase endocytosis, were internalized by macrophages and fibroblasts but were not taken up by Schwann cells. Although Schwann cells formed pits in the plasma membrane and vesicles were evident in the cytoplasm, none of the tracers used were internalized by Schwann cells. It is suggested that Schwann cell plasmalemmal and cytoplasmic vesicles have a cellular role unrelated to endocytosis or alternatively the Schwann cell basal lamina may function as a diffusion barrier to the tracers employed.

Animals↗
PubMed1992

Molecular genetic studies in black families with sickle cell anemia and unusually high levels of fetal hemoglobin.

Clinical, hematologic, and molecular genetic studies are reported for five families with SS patients having unusually high fetal hemoglobin (Hb F) levels (mean 28.3%, range 19-42%). Some of the individuals were symptom-free and one was not anemic. However, some were symptomatic despite a very high Hb F. Neither the Hb F level nor the F cell distribution entirely explained the variation in clinical severity. Molecular genetic studies identified the Senegal haplotype with the associated -158 G gamma (C----T) mutation in two of the five families. The -202 G gamma (C----G) mutation was not found in any of the individuals studied. Sequencing of the gamma-globin gene promoters to detect genetic high F determinants not detectable by restriction digestion was not performed. All AS parents and AS siblings demonstrated elevated F cells when the Senegal/-158 G gamma (C----T) mutation was present with either the beta S or beta A allele. Double heterozygosity for two different high F determinants in some SS patients is suggested by the studies in at least one family. Discordance among siblings in clinical and hematologic manifestations in two families provides additional evidence for loci regulating Hb F cell production which are not linked to the beta-globin gene clusters.

Adult↗
PubMed1991

Separation of carbohydrate-mediated microheterogeneity of recombinant human erythropoietin by free solution capillary electrophoresis. Effects of pH, buffer type and organic additives.

Free solution capillary electrophoresis has been investigated as an alternative to isoelectric focusing for the separation of the glycoforms of recombinant human erythropoietin (r-HuEPO), a primary regulator of erythropoiesis. A systematic approach was used to study the effect of pH, buffer type and organic modifiers on the resolution of the microheterogeneity of erythropoietin. The main factors for improving the resolution were the regulation of the electroosmotic flow of the running buffer and the reduction of solute-wall interaction. The best resolution of the glycoforms of r-HuEPO was obtained with a mixed buffer pH 4.0 (100 mM acetate-phosphate, 10 h preequilibration time).

Acetates↗