Synthesis and Inverse Emulsion Polymerization of Aminated Acrylamidodextran

Abstract— A chemically modified form of dextran was prepared, having a polymerizable moiety (acrylamide) and a reactive functional group (primary amine). Dextran was activated with 4-nitrophenyl-chloroformate (24 mol per polysaccharide, 9·8 mol per 100 glucose residues); 9·8% glucose residues were converted to aliphatic carbonates and 5·2% were converted to cyclic carbonates. The activated dextran was coupled with trityldiaminoethane (8 mol per 100 glucose residues), reactivated with 4-nitrophenylchloro-formate, then coupled with acryloamidodiaminohexane (6·8 mol per 100 glucose residues). The trityl group was removed by hydrolysis with trifluoroacetic acid to yield the required aminated acryloamidodextran. The modified dextran was shown to be polymerizable by inverse emulsion polymerization. Submicron particles were successfully prepared, containing functional amine groups suitable for preparing drug conjugates or for modifying the surface properties of this biomaterial.     

Human red blood cell Wright antigens: a genetic and evolutionary perspective on glycophorin A-band 3 interaction

The Wright (Wra/Wrb) blood group polymorphism is defined by an allelic change (Lys658Glu) in the band 3 protein; nevertheless, the Wrb antigen apparently requires glycophorin A (GPA) for surface presentation. To gain insight into the structural basis for this protein-protein interaction and delineate its relationship with Wrb antigen expression, we investigated GPA and band 3 sequence polymorphisms occurring in rare humans and nonhuman primates. The lack of GPA or amino acid residues 59 through 71 of GPA results in the absence of Wrb from human red blood cells (RBCs) exhibiting the MkMk, En(a-), or MiV phenotype. However, the SAT homozygous cells carried a Glu658 form of band 3 and a hybrid glycophorin with the entire GPA extramembrane domain from residues 1 through 71, yet expressed no Wrb antigen. This finding suggests that formation of the Wrb antigenic structure is dependent on protein folding and that the transmembrane junction of GPA is important in maintaining the required conformation. Comparative analyses of GPA and band 3 homologues led to the identification in the interacting regions of conserved and dispensable amino acid residues that correlated with the Wrb positive or negative status on nonhuman primates. In particular, the chimpanzee RBCs cells expressed Wrb and the Glu658 form of band 3, which is identical to humans, but their GPA contained the Gly rather than Arg residue at position 61. Taken together, the results suggest that (1) Arg61 of GPA and the proposed Arg61-Glu658 charge pair are not crucial for Wrb antigen exhibition and (2) the role of GPA for interaction with band 3, including Glu658, probably involves a number of amino acid residues located in the alpha-helical region and transmembrane junction.     

Mediastinal vessels: postoperative evaluation with MR imaging

The mediastinal vessels in 27 patients who had previously undergone vascular surgery were evaluated with use of magnetic resonance (MR) imaging for patency and the presence of stenosis. Thirty-six postoperative vessels or shunts were studied, including 11 aortas after coarctation or stenosis repair, 18 systemic-pulmonary shunts, four pulmonary artery or vein repairs, and three spiral vein grafts. Angiographic (n = 21), direct surgical (n = 1), contrast material-enhanced computed tomography (n = 1), or clinical (n = 13) findings were correlated with the MR findings. Overall, the accuracy of MR imaging for determination of patency was 100%. In patients with angiographic correlation and technically adequate MR examinations, MR imaging results were used to identify or exclude stenoses correctly in 66.7% of patent vessels. The four missed or underestimated stenoses occurred in vessels 10 mm or less in diameter.     

A sperm survival test and in-vitro fertilization outcome in the presence of male factor infertility

Several tests based on semen variables have been proposed to predict the fertilization rate in the presence of male factor infertility, but their significance remains unclear. We investigated the utility of a screening test based on sperm survival (SST) to predict the outcome of in-vitro fertilization (IVF) cycles in the presence of male factor infertility. The SST was considered normal when the percentage of motile spermatozoa 24 h after oocyte insemination was > or =50%. The sperm survival test yielded abnormal results in <90% of cycles which were unsuccessful. The sensitivity of the SST was 87% and specificity 65% with a positive predictive value of 90% in the male factor group. We believe that the SST may be a useful predictor of the IVF cycle outcome and we propose its introduction into the routine preliminary evaluation of semen samples in cases of male factor infertility.      

The use of cyclosporin in corticosteroid dependent asthma

Five children with severe asthma requiring at least 10 mg of prednisolone daily were treated with cyclosporin. Three were weaned from prednisolone, but one quickly relapsed. One girl had her steroid dose lowered but suffered unacceptable hirsutism and one child failed to respond. Cyclosporin may be useful in refractory childhood asthma. A prospective study is required to confirm this.     

Sensitivity of Gd-DTPA-enhanced MR imaging of benign extraaxial tumors

The effect of gadolinium diethylenetriaminepentaacetic acid (DTPA) on the sensitivity of cranial magnetic resonance (MR) imaging was measured in a prospective blinded study. Twenty-two consecutive patients with benign extraaxial tumors underwent MR imaging on a 1.5-T system without and with intravenous administration of Gd-DTPA. Readers independently interpreted the unenhanced and enhanced images without clinical information. The interpretations were compared with the anatomically verified diagnoses. Gd-DTPA improved the sensitivity of MR imaging for benign extraaxial tumors, especially in cases of residual or recurrent acoustic neuromas, multiple tumors (e.g., neurofibromatosis), or inconclusive unenhanced MR images. Enhancement with Gd-DTPA impaired the identification of a skull base tumor.     

Artificial urinary sphincters: plain radiography of malfunction and complications

Inflatable artificial urinary sphincters provide excellent voluntary continence. Eighty-four consecutive patients underwent implantation of artificial urinary sphincters for intractable urinary incontinence; 33 patients had 58 episodes of sphincter malfunction, and eight patients had eight complications involving a functional prosthetic sphincter. Retrospective analysis was performed to determine the value of plain radiography of the pelvis in patients with sphincter malfunction or complication. The cause of malfunction in the majority of patients was a system leak and subsequent loss of hydraulic fluid (31 occurrences; 53%). Plain radiography permitted correct identification of all instances of fluid leakage in patients with opacified prostheses. Plain radiographs were of no value in examining patients with nonopacified prostheses or the complications of cuff erosion or wound infection. Due to the low cost and noninvasive nature of plain radiography of the pelvis, we conclude that it should be used as the initial diagnostic modality in patients with previously opacified but currently dysfunctional artificial urinary sphincters.     

Philadelphia chromosome positive childhood acute lymphoblastic leukemia

In a 3-yr period, the Philadelphia chromosome (Ph1) was found in 4 of 43 children with acute lymphoblastic leukemia (ALL) in whom chromosomes were studied at diagnosis. The clinical, morphological, cytochemical, and immunologic findings in the Ph1-positive (PH1+) CASES WERE CONsistent with typical childhood ALL, indicating that identification of cases requires chromosome studies. A review of all reported cases of Ph1 + childhood ALL shows that Ph1 + patients are older and have higher initial platelet and white blood cell counts (WBC) than most children with ALL. However, a life table comparison between the reported cases of Ph1 + ALL in children and randomly selected age-, sex-, and WBC- matched controls with ALL shows the duration of first marrow remission to be significantly shorter (p less than 0.02) for the Ph1 + cases Ph1 + ALL is a distinct subtype of childhood ALL that is not rare and can be identified only by cytogenetic studies. The prognosis is poor. Cytogenetic studies should be done prospectively in a large group of children with ALL to define further the subgroup of patients and to confirm the findings of this retrospective analysis.     

Fatal airway obstruction caused by a mucous ball from a transtracheal oxygen catheter

A 50-year-old man with pulmonary fibrosis and COPD presented with worsening cough, dyspnea, chest pain, and hypoxemia of no readily apparent etiology, approximately four weeks after insertion of a transtracheal oxygen therapy catheter. Despite vigorous bronchial hygiene therapy, the patient died. Autopsy revealed obstruction of the trachea by a large mucous ball. We point out the nonspecificity of physical and radiologic findings associated with this condition and suggest that serial flow-volume loop analysis or earlier use of fiberoptic bronchoscopy might have been of assistance in premortem diagnosis of the mucous plug.