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Biomedical subjects

J M Lusher

Publications and source records attributed to J M Lusher.

At least 109 records · Page 6Linked to original sources
PubMed1981

Platelet-vessel-wall interactions: experiences with von Willebrand platelets.

Adhesion of platelets from 15 patients with von Willebrand's disease was tested in an ex vivo human umbilical vein model. Experiments employed umbilical veins still in their umbilical cords taken from patients undergoing cesarean section and platelets (fetal, adult and vW) either apyrase-washed or used as platelet-rich plasma or whole blood. F VIII R:Ag, F VIII:Rcof, and F VIII:C were measured in initial fresh plasma and in effluents from the umbilical vein segments. F VIII:Rcof increased in most perfusates. Binding of latex-linked specific antihuman F VIII R:Ag demonstrated that F VIII R:Ag existed on subendothelium and on injured endothelial cells. Scanning electron microscopy three-dimensionally displayed vW platelet--vessel-wall interactions. Although vW platelets adhered to injured vein, both qualitative and quantitative differences existed in comparison with adhesion of normal platelets. The differences correlated best with the plasma F VIII:Rcof level. The best adhesion shown by vW platelets was only 51 percent of the adhesion of control fetal or adult platelets. vW platelets had less surface activity, fewer pseudopods, and little ability to spread and pave the exposed subendothelium. Pretreatment of the vein with F VIII R:Ag antibody partly blocked adhesion. Coperfusion of cryoprecipitate with vW platelets improved their adhesivity, state of activation on subendothelium, and ability to form aggregates. ABO differences in blood cell types of fetal material and platelet donors seemed without effect, which further establishes this model's validity for studies of platelet dysfunction and platelet or endothelial reactive agents.

Animals↗
PubMed1980

Efficacy of prothrombin-complex concentrates in hemophiliacs with antibodies to factor VIII: a multicenter therapeutic trial.

The therapeutic efficacy of prothrombin-complex concentrates in patients with hemophilia and inhibitors (antibodies) to factor VIII has been increasingly debated. We therefore entered 51 hemophiliacs with factor VIII inhibitors into a double-blind randomized crossover study to compare two commercial prothrombin-complex concentrates (Konyne and Proplex) and an albumin placebo. Acute hemarthrosis of the elbow, knee, or ankle was treated with a single dose of a test preparation and assessed six hours later with objective and subjective criteria. In all measurements the concentrates were significantly more effective than the placebo. The data indicate that although prothrombin-complex concentrates, when used in a single dose, are only partially effective in the treatment of joint hemorrhage in hemophiliacs with inhibitors, their continued use for acute hemarthrosis is justified in the absence of any other effective and readily available therapy for this disorder.

Acute Disease↗
PubMed1980

Essential thrombocythemia in a child: platelet ultrastructure and function.

A nine-year-old black girl with essential thrombocythemia developed hemoptysis. Only two other cases in the English literature have been described. Ultrastructure and functional characteristics of this patient's platelets were studied. Twenty-six percent of the patient's platelets were very large (megathrombocytes). Spontaneous aggregated from the patient's platelets were not compact, and the pseudopods did not interdigitate. Both qualitative and quantitative defects in platelet organelles were detected. The microtubular system was faulty in organization. Furthermore, the number of granules (especially alpha granules) was reduced. Platelet aggregation studies demonstrated subnormal aggregation in response to ADP, epinephrine, and collagen, but aggregation with ristocetin was normal. It is postulated that a platelet membrane abnormality may be the cause of their defective platelet aggregation.

Blood Platelets↗
PubMed1980

Infections in leukemic children: a prospective analysis.

A 28-month prospective study of 54 leukemic children was carried out to determine the incidence and type of infection associated with febrile episodes. Fever was caused by infections in 84 of 199 episodes (71%). Two-thirds of the febrile episodes and 57% of the documented infections occurred when leukemic activity was demonstrable. However, only nine of 29 febrile episodes which occurred at the time of initial diagnosis of acute leukemia were due to infection. All serious bacterial infections occurred in children with absolute granulocyte counts less than 500/mm3. Septicemia was responsible for seven of the 17 deaths which occurred during the period of observation. The five children with Pseudomonas infections were colonized 10 to 30 days before they developed their infection. The majority of viral infections occurred in patients in remission, and were principally caused by cytomegalovirus, varicella-zoster virus, or Epstein-Barr virus. With the exception of one patient who died with a complex infection (CMV and Pneumocystis carinii), the children in this study responded well to viral infections.

Acute Disease↗
PubMed1979

Erythropoiesis in sickle cell anaemia during acute infection and crisis.

Erythropoiesis was evaluated in 37 patients with sickle cell anaemia, 26 of them children under 12 years of age. Mean haemoglobin, haematocrit, reticulocyte, and erythropoietin levels were similar for 11 who were asymptomatic, 11 with infections, and 12 in vaso-occlusive crisis. Mean haemoglobin, haematocrit, and reticulocyte values were significantly lower and the mean erythropoietin level significantly higher for three patients in aplastic crisis. Reticulocyte counts reflected erythropoietic activity during the asymptomatic state but were variable during infection and crisis. No erythropoietic inhibitory activity was found in any of the four clinical states. It has been suggested that erythropoietin production decreases during infection. Patients in this study responded appropriately to stress, showing no decrease in erythropoietic activity during acute infection or crisis.

Adolescent↗
PubMed1979

Structural physiology of the human spleen.

The structural physiology of the human spleen is discussed in depth here, with particular emphasis on the interrelationships between blood cells and the spleen. The unique microvasculature and structural relationships of the spleen form the basis for a number of functions important in both health and disease. Utilizing scanning electron microscopy one can visualize the interactions between blood elements and the spleen---the passage of deformable erythrocytes through narrow slits in the endothelium separating cord and sinus, the trapping of less deformable cells in the cords, the culling and pitting of abnormal or inclusion-bearing erythrocytes by splenic macrophages, as well as the sites of interaction between antigenic stimuli such as pneumococcal organisms and the T and B cells of the spleen.

Anemia, Hemolytic↗
PubMed1978

The effect of 5-hydroxytryptamine and epinephrine on newborn platelets.

Blood levels of 5-hydroxytryptamine (5-HT) and epinephrine are increased in conditions such as severe hypoxia, and hypovolemic or septic shock. The effect of these agents, which influence the blood coagulation system, were studied in vitro on platelets from newborns. 5-HT was determined in platelets from 18 newborns and 28 adults. The 5-HT content was 0.305 +/- 0.144 microgram/10(9) platelets in newborns and 0.675 +/- 0.212 microgram/10(9) platelets in the adult controls, a difference which is statistically significant (P less than 0.001). The 5-HT content of newborn platelets proved to be higher than that reported in the literature. Further studies on platelet aggregation due to 5-HT and epinephrine were then carried out. These demonstrated first-phase aggregation in 40% of cases when both 5-HT and epinephrine were applied simultaneously, while in the majority of the newborns no reaction was encountered when each of these substances was applied separately. However, in 2 cases, simultaneous application of 5-HT and epinephrine produced both first- and second-phase platelet aggregation. The reduced response of the platelets in the newborn to these aggregating agents can be considered as a protection against disseminated intravascular coagulation (DIC), particularly in high-risk situations.

Blood Platelets↗
PubMed1978

Severe factor VIII and factor IX deficiency in females.

A survey of 11 hemophilia centers produced data concerning 28 females with extremely low levels of factor VIII or IX coagulant activity. Ten of the 28 have hemophilia A, six have hemophilia B, and 12 have severe von Willebrand's disease. The 16 females who have severe factor VIII or factor IX deficiency as an isolated defect exemplify several of the possible genetic explanations for the occurrence of hemophilia in females. All 16 bruise excessively, and several have had recurrent hemarthroses. Three of these girls, ages five, 10 and 23 years, have evidence of chronic hemophilic arthropathy. The 12 females with severe von Willebrand's disease are either homozygous for von Willebrand's disease or severely affected heterozygotes. All 12 have mucous membrane bleeding. In addition, five of the 12 have recurrent hemarthroses and three have evidence of chronic joint disease. However, the major problem in the adult females with von Willebrand's disease has been extreme menorrhagia. One of the seven adults underwent irradiation sterilization and another had a hysterectomy because of menorrhagia. The others have been managed with anovulatory drugs or plasma infusions and EACA. Despite menorrhagia, five pregnancies and deliveries have been uneventful in three of these women.

Adolescent↗
PubMed1977

Childhood idiopathic thrombocytopenic purpura.

Idiopathic thrombocytopenia purpura-(ITP) in children is generally a benign, self-limited process with spontaneous recovery occurring within a matter of days or weeks. Management remains somewhat controversial to date, however, and the controversy surrounding the use or nonuse of corticosteroids will no doubt continue until critical data become available. At present, there is little or no evidence to support the claim that steroids shorten the natural course of the disease. Furthermore, evidence that steroids lessen the risk of intracranial hemorrhage is conspicuously lacking. The authors no longer use steroids in ITP; however, if one does elect to use steroids, a selective approach based on an assessment of the severity of the bleeding tendency is recommended.

Adrenal Cortex Hormones↗
PubMed1977

Idiopathic thrombocytopenic purpura in children.

ITP in childhood is most often of the acute, self-limited variety, with spontaneous recovery occurring within a matter of days or weeks. In many of these children, acute thrombopenic purpura follows in the wake of a viral infection. While the pathogenesis is not entirely clear, it seem probable that the platelet membrane is altered by virus or by soluble viral antigen-antibody complexes; platelets thus damaged become susceptible to rapid destruction by the RES. Management remains somewhat controversial. While almost all agree that corticosteroid should not be used in all cases of acute childhood purpura, there are still no clear-cut indications for their use, and no real evidence that they are of benefit in reducing the risk of the one rare but serious complication of childhood ITP, namely, intracranial hemorrhage (ICH). In approximately 5-10% of children, ITP ultimately proves to be of the chronic variety, and is in all probability the same condition that is seen in adults. Splenectomy is the treatment of choice, Another small subgroup of children have ITP of the recurrent acute variety; there is some evidence that this entity may also have an autoimmune pathogenesis. Infants born to mothers who have (or have had) ITP often manifest thrombopenia, with or without purpura and other bleeding. While this is generally a benign, self-limited process, requiring no treatment, ICH occurs in a small but significant number of affected infants and probably results from head trauma during delivery.

Acute Disease↗
PubMed1976

Arteriovenous shunts in the human spleen.

The mission of this study was to determine whether or not arteriovenous connections, indicative of a "closed" type of circulation, existed in the human spleen. Spleens from four patients requiring therapeutic splenectomy were the basis for this report. Scanning electron microscopy of plastic corrosion casts, prepared from these four spleens, revealed direct vascular conduits between splenic pulp arteries or arterial capillaries and the venous sinuses in the red pulp. Also demonstrated were a few arteriovenous shunts between pulp arteries or arterial capillaries and pulp or trabecular veins. Inclusion of sized microspheres in low-viscosity perfusion plastic illustrated that some diameters of the connecting shunts were 7-10 mum, with other shunts even smaller. Not only do arteriovenous connections exist in human spleens, but their frequency, as revealed by methods accentuating three-dimensional aspects of the splenic microcirculation, justify future reconsiderations of the functional significance of this closed type of circulation. Examination of samples of the same intact spleens, prepared by freeze-fracture and conventional critical-point drying, also revealed an "open" type circulation structure, namely, pore-patterned sinus walls that could facilitate blood cell movement from pulp cords into venous sinuses. Scanning electron microscopy thus has provided direct evidence that human spleens have both "open" and "closed" circulatory pathways in their microvasculature.

Arteriovenous Anastomosis↗
PubMed1976

IMFRA (intermittent intrathecal methotrexate and fractional radiation) plus chemotherapy in childhood leukemia.

A protocol for the prophylaxis of CNS leukemia was devised involving intermittent low-dosage radiation of the craniospinal axis combined with single intrathecal injections of MTX. The retionale for this protocol was the timing of first CNS relapses in patients not receiving prophylaxis which suggests that leukemic colonization of the CNS is not restricted to the initial stage of the disease and that periodic measures might be advantageous. The low dosage of radiation was chosen because it is well tolerated and has been found temporaily effective in overt CNS relapse. The two series of patients were comparable as to various parameters. Results after three years of observation were comparable to those obtained by other with a single initial course of high-dose radiation, with an expected 50% uninterrupted complete 5-year remission. On the basis of 30 months follow up in 26 patients, the therapy is well tolerated. An increase in morbidity due to infections in remission was not associated with a higher mortality.

Adolescent↗
PubMed1976

The human spleen as revealed by scanning electron microscopy.

The three-dimensional world of the spleen was explored by scanning electron microscopy on both arterially perfused and nonperfused specimens, as well as on plastic corrosion casts of splenic vasculatures. Of 25 spleens studied, 18 were examples of hypersplenism. These were contrasted to 7 essentially normal spleens taken from children being staged for treatment of Hodgkin's disease whose spleens proved to be uninvolved in the pathologic process. Splenic sinuses in all 25 spleens were typified by a degree of porosity. RBC were caught in the act of entering sinuses from splenic cords. These sinus windows thus represent one end of an "open" circulation pathway. In casts of microvasculature, direct arteriovenous connections were demonstrated, thus establishing an anatomical basis for an often disputed "closed" circulation pathway. Spleens from 7 patients with hereditary spherocytosis had a super abundance of red pulp. Splenic cords were thickened and crowded with spherocytes, many of which presented slightly wrinkled membranes, as were also noted on the peripheral blood RBC. It is possible that these membrane features are unique for HS and reflect the intrinsic membrane abnormality in protein composition. The 7 spleens from chronic idiopathic thrombocytopenic purpura had white pulp as the predominant region. Germinal centers were frequent. Lymphocytes and plasma cells with well-developed microvilli were suggestive that release of antiplatelet antibody might be occurring in white pulp. Platelets were especially notable in peripheral white pulp and marginal zones. Platelet clumps were observed, generally adjacent to spleenic macrophages.

Anemia, Sickle Cell↗