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PubMed1988

Diamond burring and surgical keratectomy. Morphologic comparison in the rabbit.

We compared the effects of diamond burring keratectomy (DBK) and surgical superficial lamellar keratectomy (SLK) on the rabbit corneal epithelial healing rate and corneal morphology 1, 4, 7, and 14 days after wounding. Epithelial defects healed significantly more slowly following 10-mm-diameter SLK than following DBK. Restoration of normal epithelial morphology occurred within two weeks in the DBK corneas. During the same interval, SLK corneas showed poor transition of basal to superficial cell morphology. Four days after surgery, the DBK corneas all exhibited marked keratocyte depletion in the anterior stroma but fibrocytes uniformly repopulated this area by 14 days after wounding. Conversely, the SLK corneas all had a hypercellular band of fibrocytes in the anterior stroma by four days following surgery and continued to increase in cellularity through 14 days after wounding. These data indicate that DBK is the preferred procedure for creation of a recipient bed for epithelial lenticles in keratoepithelioplasty and conjunctival transplantation.

Animals↗
PubMed1997

Epiretinal membrane delamination with a diamond knife.

Removal of membranes from the retinal surface is an integral part of many vitreoretinal surgical procedures. Two-handed tissue delamination with a knife allows precise and accurate control of dissection planes. A newly designed diamond knife provides the consistently sharp cutting edge required for this technique.

Epiretinal Membrane↗
PubMed1977

Diamond-shaped anastomosis for congenital duodenal obstruction.

A retrocolic side-to-side duodenojejunostomy has been a generally accepted standard operative procedure for the correction of congenital duodenal atresia and stenosis. However, this operation has the complication of delayed anastomotic function that often requires a use of transanastomotic feeding tube or intravenous hyperalimentation. A diamond-shaped side-to-side duodenoduodenal anastomosis has been performed in nine consecutive cases of congenital duodenal obstruction, with satisfactory results. A transverse incision is made in the dilated proximal duodenum, and a longitudinal incision in the duodenum distal to the obstruction. The stoma is fashioned by approximating the end of each incision to the appropriate midportion of the other incision. Transanastomotic feeding tubes were not used and oral feedings were easily tolerated. This technique offers the theoretical advantage of providing a more physiological gastrointestinal pathway.

Child, Preschool↗
PubMed1995

Diamond-Blackfan anemia and malignancy. A case report and a review of the literature.

BACKGROUND: Diamond-Blackfan anemia (DBA) is a congenital bone marrow failure syndrome involving the erythropoietic lineage. A preleukemic predisposition has been suggested but not proven. METHODS: The development of Hodgkin's disease in a 15-year-old boy with DBA, in remission for 13 years after cessation of steroid therapy, is described. Review of the literature revealed 11 other cases of malignancy (10 hematologic) in DBA. RESULTS: This patient, together with those described in the literature, shows that the incidence of hematological malignancy in DBA is increased (2.5% of all reported cases of DBA). Treatment was successful in three, including one after allogeneic bone marrow transplantation and our patient in whom recurrence of DBA complicated treatment. CONCLUSIONS: The incidence of hematologic malignancies in patients with DBA is increased. Treatment can be successful but may be complicated by recurrence of DBA. Bone marrow transplantation should be considered for patients with a suitable donor as part of treatment of patients with DBA and hematologic malignancy.

Adolescent↗
PubMed2002

Bis(mu-oxo)dimetal "diamond" cores in copper and iron complexes relevant to biocatalysis.

Although quite a familiar feature in high-valent manganese chemistry, the M(2)(mu-O)(2) diamond core motif has only recently been found in synthetic complexes for M=Cu or Fe. Structural and spectroscopic characterization of these more reactive Cu(2)(mu-O)(2) and Fe(2)(mu-O)(2) compounds has been possible through use of appropriately designed supporting ligands, low-temperature handling methods, and techniques such as electrospray ionization mass spectrometry and X-ray crystallography with area detector instrumentation for rapid data collection. Despite differences in electronic structures that have been revealed through experimental and theoretical studies, Cu(2)(mu-O)(2) and Fe(2)(mu-O)(2) cores exhibit analogously covalent metal-oxo bonding, remarkably congruent Raman and extended X-ray absorption fine structure (EXAFS) signatures, and similar tendencies to abstract hydrogen atoms from substrates. Core isomerization is another common reaction attribute, although different pathways are traversed; for Fe, bridge-to-terminal oxo migration has been discovered, while for Cu, reversible formation of an O-O bond to yield a peroxo isomer has been identified. Our understanding of biocatalysis has been enhanced significantly through the isolation and comprehensive characterization of the Cu(2)(mu-O)(2) and Fe(2)(mu-O)(2) complexes. In particular, it has led to the development of new mechanistic notions about how non-heme multimetal enzymes, such as methane monooxygenases, fatty acid desaturase, and tyrosinase, may function in the activation of dioxygen to catalyze a diverse array of organic transformations.

Catalysis↗
PubMed1986

Comparative activity of erythrocyte adenosine deaminase and orotidine decarboxylase in Diamond-Blackfan anemia.

It previously has been reported that red blood cells (RBC) of patients with Diamond-Blackfan syndrome (DBS) have increased activity of orotidine decarboxylase (ODC) and adenosine deaminase (ADA). The studies reported here compared the activity of these two enzymes in DBS erythrocytes, cord blood, and reticulocytes. The activity of ODC, although increased in some DBS erythrocytes, was not significantly different from that seen in cord RBC or reticulocytes. In contrast, RBC-ADA activity was increased in 23 of 26 DBS patients; and this enzyme elevation was distinct from that seen in cord blood and reticulocytes. Moreover, ADA activity was normal in 26 of 27 patients with transient erythroblastopenia of childhood (TEC). Taken together, these data indicate RBC-ADA activity is more sensitive than ODC as a marker of DBS. In addition, RBC-ADA activity continues to be useful for distinguishing DBS and TEC in most patients with RBC hypoplasia.

Adenosine Deaminase↗
PubMed1992

Cyclosporin A treatment for Diamond-Blackfan anemia.

Diamond-Blackfan anemia (DBA) is characterized by a variable response to corticosteroid therapy. Patients poorly responsive to acceptable doses of steroid treatment require long-term transfusion therapy. We have treated three patients with DBA with the immunosuppressive agent cyclosporin A with limited success. Patients 1 (DS) and 2 (LS), half-siblings, were 13 and 9 years old, respectively, and remained transfusion independent for many years on steroid therapy. Both patients manifest steroid-associated growth failure and osteopenia, with resultant orthopedic complications. Oral cyclosporin therapy sufficient to achieve trough serum levels of 100-200 ng/ml was associated with a brisk 50-100% increase in hematocrit within 1 month of initiation of treatment and allowed for a gradual tapering of prednisone dose to approximately 20% of prior established maintenance dose. After 7-8 months, both patients developed progressive decline in hematocrit level requiring increased prednisone dose and, ultimately, transfusion support. Patient 3 (RD), a 5-year-old child with steroid refractory, transfusion-dependent DBA, was entirely unresponsive to cyclosporin therapy. No cyclosporin-associated toxicity occurred. Our observations indicated that cyclosporin A can transiently ameliorate the hematologic course of some patients with DBA. Further studies are in order to determine its mechanism of action and potential clinical utility in patients unresponsive to acceptable doses of steroid.

Adolescent↗
PubMed1990

Congenital hypoplastic (Diamond-Blackfan) anemia in seven members of one kindred.

Congenital hypoplastic (Diamond-Blackfan) anemia is a rare macrocytic anemia, generally presenting during infancy or childhood. The condition usually occurs sporadically or in a pattern consistent with autosomal recessive inheritance, although autosomal dominant transmission has been proposed in some kindreds. We report the largest known kindred of congenital hypoplastic anemia, with at least 7 affected individuals over 3 generations, and propose that studies of this kindred may be useful for identifying the mechanism by which their genetic abnormality results in congenital hypoplastic anemia. Erythropoietic investigations on relatives show no inhibitors of erythropoiesis in serum, T-lymphocytes, or macrophages. Their erythroid progenitor cells (CFU-E and BFU-E) were generally quantitatively normal, and were capable of rapid proliferation, as judged by cell-cycle shortening. However, their erythroid progenitors displayed a relative insensitivity to recombinant erythropoietin, and produced relatively few normoblasts per erythroid progenitor cell. We propose that these and subsequent studies may be helpful in selecting candidate genes responsible for the molecular defect in this kindred.

Adolescent↗
PubMed2001

Bilateral microtia and cleft palate in cousins with Diamond-Blackfan anemia.

We report on maternal first cousins with bilateral microtia, micrognathia, cleft palate and hematologic findings of Diamond-Blackfan anemia (DBA). The similarity of findings shared between our cases and a female reported by Hasan and Inoue [1993] suggests that this is a distinctive syndrome, rather than a chance association. DBA is a heterogeneous disorder, caused in about 25% of cases by heterozygous mutations in the RPS19 gene (DBA1). Mutation analysis in our cases did not show an RPS19 mutation, and 2 alleles were present in each. Segregation analysis for DBA1 on chromosome 19 and DBA2 on 8p23 was not consistent with linkage. We conclude that this syndrome of microtia, cleft palate and DBA is not allelic to known DBA loci.

Abnormalities, Multiple↗
PubMed2004

The chemotaxis defect of Shwachman-Diamond Syndrome leukocytes.

Shwachman-Diamond Syndrome (SDS) is a rare autosomal recessive, multisystem disorder presenting in childhood with intermittent neutropenia and pancreatic insufficiency. It is characterized by recurrent infections independent of neutropenia, suggesting a functional neutrophil defect. While mutations at a single gene locus (SBDS) appear to be responsible for SDS in a majority of patients, the function of that gene and a specific defect in SDS neutrophil behavior have not been elucidated. Therefore, employing 2D and 3D computer-assisted motion analysis systems, we have analyzed the basic motile behavior and chemotactic responsiveness of individual polymorphonuclear leukocytes (PMNs) of 14 clinically diagnosed SDS patients. It is demonstrated that the basic motile behavior of SDS PMNs is normal in the absence of chemoattractant, that SDS PMNs respond normally to increasing and decreasing temporal gradients of the chemoattractant fMLP, and that SDS PMNs exhibit a normal chemokinetic response to a spatial gradient of fMLP. fMLP receptors were also distributed uniformly through the plasma membrane of SDS PMNs as in control PMNs. SDS PMNs, however, were incapable of orienting in and chemotaxing up a spatial gradient of fMLP. This unique defect in orientation was manifested by the PMNs of every SDS patient tested. The PMNs of an SDS patient who had received an allogenic hematopoietic stem cell transplant, as well as PMNs from a cystic fibrosis patient, oriented normally. These results suggest that the defect in SDS PMNs is in a specific pathway emanating from the fMLP receptor that is involved exclusively in regulating orientation in response to a spatial gradient of fMLP. This pathway must function in parallel with additional pathways, intact in SDS patients, that emanate from the fMLP receptor and regulate responses to temporal rather than spatial changes in receptor occupancy.

Adolescent↗
PubMed2006

AFM studies of metal deposition: instantaneous nucleation and the growth of cobalt nanoparticles on boron-doped diamond electrodes.

In situ atomic force microscopy (AFM) is used to study the growth of cobalt nuclei on a boron doped diamond electrode under potentiostatic control. The rate of growth of the nuclei at the electrode surface is monitored using AFM as a function of time at different deposition potentials. The nucleation of cobalt nuclei is found to be "instantaneous" and the growth of the nuclei is shown to be kinetically rather than diffusionally controlled over periods of tens and hundreds of seconds. At very short times (<10 seconds) the kinetics of nucleation are apparent.

Journal Article↗
PubMed2005

Sexual size dimorphism and growth plasticity in snakes: an experiment on the Western Diamond-backed Rattlesnake (Crotalus atrox).

We conducted an experiment to examine the effects of sex and food intake on growth, mass gain, and attainment of sexual maturity in Western Diamond-backed Rattlesnakes (Crotalus atrox). We also measured testosterone levels to determine whether testosterone might be involved in the male-biased sexual size dimorphism observed in this species. We collected neonate rattlesnakes and raised them in the laboratory for 2 years on either a high-intake diet (fed one mouse per week) or a low-intake diet (fed one mouse every 3 weeks). High-intake snakes grew and gained mass more rapidly than low-intake snakes, but males did not grow or gain mass more rapidly than females in either treatment group. High-intake snakes attained reproductive maturity earlier than low-intake snakes, indicating that size, not age, is the critical determinant of reproductive maturity. Males had higher levels of testosterone than females but did not grow more quickly, suggesting that testosterone may not affect growth in this species and may therefore not be the proximate determinant of sexual size dimorphism.

Animal Nutritional Physiological Phenomena↗
PubMed2006

Simple and reliable procedure for end-to-side microvascular anastomosis: the diamond technique.

In the last few decades, microsurgery has become a reliable technique in reconstructive surgery due to numerous technical and conceptual advances. End-to-side anastomosis is currently preferred by many microsurgeons. Many recent clinical and experimental studies showed no significant difference between the slit and hole techniques for end-to-side anastomosis. We propose a different technique, based on geometrical planning of arteriotomies on both the recipient and pedicle artery. The diamond technique is easy to execute, simple, and reliable, with many advantages, and should be kept in mind in selected patients.

Anastomosis, Surgical↗
PubMed2005

Shwachman-Diamond syndrome.

Shwachman-Diamond syndrome (SDS) is an inherited marrow failure disorder with varying cytopenia, pancreatic dysfunction, and metaphyseal dysostosis. SDS is also characterized by a risk of myelodysplasia and leukemia in up to one third of the patients. Over the last 5 years, major advances have been made in understanding the bone marrow phenotype. The gene associated with the disease, SBDS, has recently been identified. Herein we provide an update on the clinical features, the hematopoietic defects, and the genetics of the disease as they are currently understood. We also review the diagnostic and therapeutic approaches to the hematological complications in the syndrome.

Bone Marrow Diseases↗
PubMed2008

MRI findings in Shwachman diamond syndrome.

Shwachman Diamond Syndrome (SDS) is a rare congenital disorder characterized by pancreatic insufficiency, bone marrow dysfunction, and skeletal changes. Because of the heterogeneous clinical presentation and the limits of laboratory tests that assess pancreatic insufficiency, the diagnosis of SDS can be challenging. Pancreatic lipomatosis, a typical feature of this syndrome, is also difficult to assess by direct tissue sampling. In these circumstances, magnetic resonance imaging (MRI) provides a readily available, noninvasive tool to evaluate the pancreatic fat content. We report a case of a 12-month-old male in which abdominal MRI was used to confirm the clinical diagnosis of SDS.

Bone Marrow Diseases↗
PubMed1988

Altered fetal cardiac flow patterns in pure red cell anaemia (the Blackfan-Diamond syndrome).

In a case of fetal anaemia due to pure red cell anaemia (Blackfan-Diamond syndrome), two-dimensional fetal Doppler echocardiography revealed an altered blood flow velocity pattern with entire incorporation of the atrial contraction component in the early passive filling phase of the right ventricle. Intracardiac blood velocities were increased, whereas cardiac output was only moderately increased. The fetal heart rate was normal. It is concluded that in fetal anaemia the compensatory mechanisms are limited and restricted to an increase in stroke volume. The hypothesis that chronic fetal anaemia is associated with 'high output cardiac failure' corresponds well with the present findings. The technique described may prove to be useful in the early diagnosis of fetal anaemia.

Anemia↗
PubMed1993

Erythropoiesis in Diamond-Blackfan anemia and the role of interleukin 3 and steel factor.

Diamond-Blackfan anemia (DBA) is pleiotropic clinically and in vitro, and there is a strong suspicion that DBA is really a family of diseases that shares a common hematological phenotype. Although standard clonogenic assays of erythroid progenitors have been very informative about pathogenesis, they are not diagnostic of DBA, have no relationship to the clinical presentation and do not relate to the hemoglobin level or to the percentage of marrow erythroids at the time of study. Studies on progenitor-enriched marrow cells have furthered our understanding of DBA and have clearly shown marked differences among patients with respect to erythropoietin and "burst-promoting activity" responsiveness. In vitro addition of corticosteroids, interleukin 3 (IL-3) and/or Steel factor has produced a corrective effect on erythropoiesis in some DBA patients and has prompted clinical trials with IL-3 with variable results. It is clear that there is a disparity between the vitro data and clinical outcome, and therefore, the erythroid progenitor responsiveness to steroids and cytokines has limited predictive value clinically. Based on more than two decades of study, a model of DBA has evolved based on putative blocks at various stages along the erythropoietic differentiation pathway. These blocks likely represent a disorder of receptor-ligand interaction involving one or more growth-promoting cytokines.

Cell Differentiation↗