Multiple-electron transfer in a single step. Design and synthesis of highly charged cation-radical salts.

[structure: see text]. Macromolecules 1c and 2c bearing multiple redox-active sites are synthesized by an efficient palladium-catalyzed coupling of 2,5-dimethoxytolylmagnesium bromide with readily available hexakis(4-bromophenyl)benzene and tetrakis(4-bromophenyl)methane. These macromolecular electron donors undergo reversible oxidation at a constant potential of 1.15 V vs SCE to yield robust, multiply charged cation radicals that are isolated in pure form using SbCl(5) as an oxidant. These nanometer-size cation-radical salts are shown to act as efficient "electron sponges" toward a variety of electron donors.

Metalloproteinase increases in the injured rat spinal cord.

Up-regulation of matrix metalloproteinases MMP-9 and MMP-2 after injury to the spinal cord (SCI) is demonstrated. MMP-9 activity maximized at 12-24 h, and MMP-2 rose at 5 days post-injury. MMP-3 was not detectable by zymographic analysis, so its level of expression was, at most, very low. The level of tissue inhibitor of metalloproteinases in the spinal cord was not altered by injury, perhaps permitting increased MMP-9 and MMP-2 activities in situ. Ablating them with an antibody demonstrated that infiltrating neutrophils were the principal source of MMP-9 activity after spinal cord injury, suggesting that neutrophils utilize that proteinase in responding to spinal cord injury. MMP-9 and MMP-2 probably contribute to breakdown of the extracellular matrix following SCI.

Biological consequences of thrombin receptor deficiency in mice.

The thrombin receptor (ThrR) is a membrane-bound, G-protein-coupled receptor for the serine protease thrombin. This receptor is expressed in a wide variety of cells and tissues, and elicits a range of physiological responses associated with tissue injury, inflammation, and wound repair. To achieve a better understanding of the physiological role of the ThrR, we have employed homologous recombination to create mice with a disrupted ThrR gene. Following heterozygous (+/-) intercrosses, a total of 351 surviving offspring were genotyped. Only 7% of these offspring were identified as homozygous (-/-) for the disrupted allele, indicating a profound effect on embryonic development. Paradoxically, adult ThrR-/- mice appeared to be normal by anatomical and histological analysis, including their platelet number and function. Similarly, ThrR deficiency had no detectable effect in adult ThrR-/- mice on basal heart rate, arterial blood pressure, vasomotor responses to angiotensin II and acetycholine, and coagulation parameters, even though the ThrR is expressed in many cardiovascular tissue types. In addition, the loss of ThrR function in the peripheral vasculature of adult ThrR-/- mice was confirmed by the absence of various standard hemodynamic effects of the ThrR-activating peptides SFLLRN-NH2 and TFLLRNPNDK-NH2. Our results indicate that ThrR deficiency has a strong impact on fetal development; however. ThrR-/- mice that proceed to full development display surprisingly little change in phenotype compared to the wild-type.

Novel 6-alkoxypurine 2',3'-dideoxynucleosides as inhibitors of the cytopathic effect of the human immunodeficiency virus.

Twenty-one 6-alkoxypurine 2',3'-dideoxynucleosides were enzymatically synthesized with nucleoside phosphorylases purified from E. coli. Eighteen analogs exhibited anti-HIV-1 activity in MT4 cells. Two analogs, 6-(hexyloxy)-(17) and 6-(heptyloxy)-(18) purine 2',3'-dideoxynucleoside, were as potent as 2',3'-dideoxyinosine (ddI, didanosine, Videx). Although the antiviral activities of 17 and 18 were equivalent, 18 was more cytotoxic. Analogs containing less than four carbons in the 6-alkoxypurine substituent exhibited weak anti-HIV-1 activity. Analogs containing more than seven carbons in the 6-alkoxypurine substituent were too cytotoxic to be effectively evaluated for antiviral activity. Several 6-alkoxypurine 2',3'-dideoxynucleosides were evaluated for substrate activity with calf intestinal adenosine deaminase (ADA). Increasing the carbon chain length of the 6-alkoxypurine substituent decreased the rate of dealkoxylation. The best substrate in this series was 6-methoxypurine 2',3'-dideoxynucleaside (1); however, the rate of dealkoxylation of 100 microM 1 was 0.17% of the rate of deamination of 100 microM 2',3'-dideoxyadenosine. Compound 17, the most potent anti-HIV-1 analog, was not a substrate for ADA. EHNA (erthro-9-(2-hydroxy-3-nonyl)adenine), a potent inhibitor of ADA, had little effect on the antiviral activities of 17 and ddI. In contrast, coformycin, a potent inhibitor of both ADA and AMP deaminase, dramatically decreased the antiviral activity of 17, but not the antiviral activity of ddI. Thus, AMP deaminase appeared to be involved in the anabolism of 17. The pharmacokinetic profile of 17, the most promising analog in this series, was determined in the rat. At least seventeen metabolites of 17, including ddI, were detected in plasma samples. This analog also had poor oral bioavailability.

Di- and triester prodrugs of the varicella-zoster antiviral agent 6-methoxypurine arabinoside.

6-Methoxypurine arabinoside (9-beta-D-arabinofuranosyl-6-methoxy-9H-purine, 1) has potent and selective activity against varicella-zoster virus in vitro. An unfavourable metabolic profile observed with oral dosing in the rat led to the preparation of a variety of 2',3',5'-triesters (2a-n) and several 2',3'-, 2',5'-, and 3',5'-diesters of this arabinoside (3a-n, 4a-f, and 5a-j, respectively). The compounds were evaluated as prodrugs by measuring the urinary levels of 1 in rat urine after oral dosing. With the exception of triacetate 2a, the triesters failed to significantly enhance bioavailability. Administration of compound 2a resulted in a 3-fold increase in systemic availability of 1, possibly because of its increased water solubility (1.6 times more soluble than 1) and only slightly increased relative log P value (1.93 vs 0.50 for 1). The longer chain aliphatic triesters and aromatic triesters had lower water solubilities and increased lipophilic partitioning. These factors might account for the lower systemic bioavailability of these compounds. In contrast, the diesters, especially the aliphatic diesters, showed significantly improved systemic availability. This might be a consequence of the higher aqueous solubilities and enhanced partition coefficients seen with these compounds. 2',3'-Diacetate 3a showed the best combination of high systemic availability and water solubility of all the prodrugs of 1.

Anti-human immunodeficiency virus synergism by zidovudine (3'-azidothymidine) and didanosine (dideoxyinosine) contrasts with their additive inhibition of normal human marrow progenitor cells.

The anti-human immunodeficiency virus (HIV) activity and hemopoietic toxicity of zidovudine (AZT) and didanosine (dideoxyinosine;ddI), alone and in combination, were assessed in a variety of cell types. AZT was more potent than ddI as an inhibitor of HIV in vitro. Synergistic inhibition of HIV by the combination of these agents was observed in MT4 cells, peripheral blood lymphocytes, and macrophages. Toxicity assessment in vitro by using progenitor (erythroid and granulocyte-macrophage) colony-forming assays with normal human bone marrow showed ddI to be less toxic than AZT. Addition of inhibitory concentrations of ddI to AZT resulted in additive inhibition of progenitor CFUs. These in vitro findings suggest that combinations of ddI and AZT at appropriately modified doses may provide an enhanced degree of selectivity in anti-HIV chemotherapy.

Inferior rectus recession for vertical tropia after cataract surgery.

Four patients with de novo onset of persistent vertical tropia ranging from 4 to 11 prism diopters (PD) after cataract surgery underwent inferior rectus recession. Deviations were stable and fuseable with prism preoperatively for 4 to 6 months. Three patients regained single binocular vision in all fields of gaze. Macular change developed in one eye of a diabetic patient, precluding adequate postoperative assessment. Mechanical and sensory factors, detailed assessment of pertinent preoperative findings, and intraoperative management are discussed. Previous literature is reviewed.

Crystallization and preliminary x-ray investigation of thymidine phosphorylase from Escherichia coli.

Crystals of thymidine phosphorylase from Escherichia coli have been grown from solutions of ammonium sulfate. The crystals are tetragonal, space group P4(1)2(1)2 or P4(3)2(1)2; the axes are a = 132.0 (1) and c = 67.2 (1) A. The crystals are quite stable to x-rays and diffract beyond 2.6-A resolution. The molecule is a dimer and utilizes the 2-fold symmetry of the space group, resulting in one subunit per asymmetric unit.

Ptosis associated with botulinum toxin treatment of strabismus and blepharospasm.

The incidence, severity, and duration of ptosis after botulinum neurotoxin type A (BAT) injections into extraocular or orbicularis muscles were reviewed retrospectively. Even though lid droop frequently complicated botulinum toxin treatment in this series, no loss of vision or permanent ptosis was encountered. Sixty-seven injections were completed in 44 patients between September 1982 and December 1983. The records were reviewed to determine the incidence of ptosis after these 67 injections. Information was not adequate to ascertain the presence or absence of ptosis after 10 injections. Some degree of ptosis developed after 30 (53%) of the 57 injections with adequate follow-up history. Marked ptosis occurred after 12 (21%) of the 57 injections. The posttreatment lid droop in these 12 cases was potentially visually significant. All cases of ptosis, which impinged on the visual axis, resolved to a level permitting undisturbed vision by eight weeks after toxin injection. The incidence of ptosis was similar in patients who received injections into their medial rectus muscles and in patients who received injections into their lateral rectus muscles. However, an increased incidence of marked ptosis may be associated with the injection of previously operated muscles. Toxin dosage, patient age, and quality of the electromyogram used to monitor the injection showed no statistically significant relationship to the ptosis.

Thiazolidine-2-carboxylate derivatives formed from glyoxylate and L-cysteine or L-cysteinylglycine as possible physiological substrates for D-aspartate oxidase.

Adducts of glyoxylate with L-cysteine or L-cysteinylglycine were found to be excellent substrates at low concentrations for beef kidney D-aspartate oxidase. Evidence is presented that cis-thiazolidine-2,4-dicarboxylate and its glycine amide are the actual substrates, and that both are converted in the enzymic reaction to 4-substituted thiazoline-2-carboxylates. The results imply that these thiazolidine derivatives are the likely physiological reactants for mammalian D-aspartate oxidase.

Bilateral endophthalmitis in acute bacterial endocarditis.

A 53-year-old diabetic woman had ketoacidosis, urinary tract infection, and bilateral endophthalmitis. She subsequently developed a ruptured chorda tendineae of the mitral valve, and a diagnosis of acute bacterial endocarditis was made. No organisms were cultured during life or at autopsy. At autopsy, bilateral nongranulomatous panophthalmitis was found with perinephric, myocardial, intracranial, and mitral valve abscesses.

Thermal burns: the management of thermal burns of the lids and globes.

Our experience with 40 patients with eyelid and globe burns is reviewed. Initial emphasis should be placed on close monitoring, particularly of partially alert patients, debridement and treatment of corneal exposure with artificial tears and scleral shells when needed. The use of soft contact lenses in 2 patients with exposure was unsuccessful. Surgical treatment should be initiated when corneal exposure fails to respond to medical therapy. It is advisable to wait for the end stage of scarring so as to optimize chances for a single definitive correction. The use of retroauricular, supraclavicular or inner arm skin for grafting whenever possible is advised. The use of Frost sutures, tie-on dressings, and separate operations for upper and lower lids is recommended. Superficial wound sepsis is not a contraindication to grafting. Preoperative systemic or topical antibiotics do not seem to affect the outcome of the graft.

Unusual ocular presentation of sarcoidosis.

A patient is presented with a probable sarcoid granuloma involving the surface of the optic disc. Systemic steroid administration resulted in a resolution of the fundus changes and return of normal vision. Although ocular sarcoidosis is usually manifested by anterior segment inflammation, it is apparent that it may also produce proliferative lesions of the optic nerve.