Comparisons in the behavior of stable copper(II), silver(II), and gold(II) complexes in the gas phase: are there implications for condensed-phase chemistry?

Experiments conducted in the gas phase have led to the formation of a series of stable gold(II) complexes with nitrogen- and oxygen-containing ligands. Such complexes are very rare in condensed-phase chemistry. However, there is also a significant group of potential ligands, for example, H2O and NH3, for which stable complexes could not be formed. There are strong similarities between these observations and earlier results presented for silver(II), but both metal ions behave markedly different from copper(II). As a group the majority of successful gold(II) ligands are characterized by being good sigma donor-pi acceptor molecules; however, it is also possible to understand the ability of individual ligands to stabilize the metal ion in terms of a simple electrostatic model. Application of the latter reveals a semiquantitative trend between the physical properties of a ligand, e.g. ionization energy, dipole moment, and polarizability, and the ligand's ability to stabilize either Cu(II), Ag(II), or Au(II). The model successfully accounts for the preference of Cu(II) for aqueous chemistry, in comparison to the complete absence of such behavior on the part of Ag(II) and Au(II). Ligands from recent examples of stable condensed-phase gold(II) complexes appear to meet at least one of the criteria identified from the model.

Chorionicity inaccurately predicted by early ultrasound: a case report.

Ultrasound has been found to be extremely accurate in diagnosing the chorionicity of multiple gestations. Prenatal counselling and/or planning for selective termination is most often based on the sonographic prediction of chorionicity. We present a case of triplet pregnancy in which early sonographic prediction of chorionicity did not match the pathological diagnosis at delivery.

The necessity of acute bone grafting in diaphyseal forearm fractures: a retrospective review.

OBJECTIVE: To determine the union rate of forearm fractures where acute bone grafting was recommended but not performed. DESIGN: Retrospective review. SETTING: Regional level one trauma center. PATIENTS: The criteria for inclusion in the study were patients with closed growth plates and a diaphyseal fracture of the radius, ulna, or both (including Monteggia and Galeazzi fracture-dislocations) that were treated with plate fixation. Patients were excluded from the study if they were lost to follow-up before radiographic documentation of bone union. The review identified 198 fractures that were eligible for inclusion. Fifteen fractures were excluded. INTERVENTION: The method of treatment of each fracture was open reduction and plate fixation with or without bone grafting. MAIN OUTCOME MEASUREMENT: Fracture union. RESULTS: The overall union rate in comminuted, nongrafted forearm fractures (open and closed) was 98% (99/101; 95% confidence interval: 93-100%). The union rate in closed, comminuted, nongrafted forearm fractures was 97% (74/76; 95% confidence interval; 91-100%). CONCLUSIONS: Open reduction and internal fixation of comminuted diaphyseal forearm fractures without bone grafting in this study produced union rates comparable to those reported for open reduction and internal fixation of comminuted forearm fractures with acute bone grafting. This study suggests that routine use of bone grafting in comminuted forearm fractures is not indicated.

Hypertensive encephalopathy in childhood.

Hypertensive encephalopathy is an uncommon but recognized complication of malignant hypertension in children. We reviewed the clinical course, laboratory studies, and outcomes of 12 patients with hypertensive encephalopathy seen at the University of Iowa Hospitals and Clinics between 1979 and 1994. The most common presenting symptoms were seizures, headache, and vision changes. Laboratory studies were nonspecific and in some patients were normal. Hypertensive encephalopathy is a clinical diagnosis. Management consists of recognition of this syndrome and aggressive treatment of hypertension. The neurologic outcome in our series was good.

Another case of virologically confirmed zoster sine herpete, with electrophysiologic correlation.

A third virologically-confirmed case of thoracic-distribution zoster sine herpete is reported. Electromyography (EMG) of paraspinal muscles demonstrated frequent fibrillation potentials restricted to chronically painful thoracic root segments. Treatment with intravenous acyclovir and oral famciclovir were ineffective. These findings suggest the usefulness of EMG of muscles corresponding to painful dermatomes, combined with virologic studies, to support the diagnosis of zoster sine herpete.

Zoster sine herpete, a clinical variant.

Two otherwise healthy immunocompetent men, ages 62 and 66 years, experienced years of radicular pain without zoster rash. An extensive search for systemic disease and malignancy was negative. Varicella-zoster virus DNA, but not herpes simplex virus DNA, was found in the cerebrospinal fluid of the first patient 5 months after the onset of pain, and in the second patient 8 months after the onset of pain. Prolonged radicular pain without zoster rash combined with the presence of varicella-zoster virus in the cerebrospinal fluid indicates that both men had zoster sine herpete, and strongly supports this syndrome as a clinical variant.

The de-endothelialized rat carotid arterial graft: a versatile experimental model for the investigation of arterial thrombosis.

A novel model of arterial thrombosis was developed. A mechanical endothelium-denuding injury was created (using a scalpel blade) on harvested, freezer-stored rat carotid arteries. Vessel length of 5 mm. were grafted into the femoral arteries of recipient Sprague-Dawley rats using microvascular anastomotic technique. Patency rates in untreated animals were compared with those in animals receiving systemic aspirin or heparin. The control group patency after 2 hours of flow was 15%, while grafts in aspirin- and heparin-treated animals achieved 35% and 95% patency rates, respectively. Uninjured non-frozen carotid grafts in untreated animals yielded a 95% patency rate, while frozen grafts achieved an 80% patency. Therapeutic levels of aspirin, heparin, and urokinase were confirmed through tail bleeding and whole blood clotting tests, as well as platelet aggregation studies and scanning electron microscopy of the graft lumenal surfaces. A long-term series using syngeneic grafts placed in recipients (Lewis-to-Lewis) and employing systemic heparinization demonstrated maintenance of patency for 4 weeks. Scanning electron microscopy revealed good re-endothelialization, well advanced by one week. Histology confirmed the regrowth of endothelial cells, but showed sparse cellular repopulation of medial and adventitial layers. The mechanical injury model was compared to enzymatic de-endothelialization (using trypsin or collagenase), for which patency rates were similar (10% and 0%, respectively). Trypsin de-endothelialized vessels were tested in vitro for the amount of active trypsin remaining bound to the lumenal surface; no detectable activity was found when trypsin inhibitor was applied following trypsin treatment. The versatility of allowing both in vitro evaluation and in vivo patency assessment demonstrates the uniqueness and value of this new model, offering an avenue toward more direct investigations of surface-mediated thrombotic processes.

The effect of high-dose steroids on MRI gadolinium enhancement in acute demyelinating lesions.

Gadolinium (Gd) enhancement of brain lesions by MRI is a marker of active blood-brain barrier damage secondary to an inflammatory process. We studied the effects of high-dose (1,000 mg/d) intravenous (IV) methylprednisolone (Mp) for 4 to 8 days on Gd-enhancing lesions in seven patients with acute demyelinating diseases and compared pretreatment brain MRIs with studies obtained 1 to 4 days after treatment. Five patients had complete suppression, and two had significant suppression of Gd enhancement following treatment. In addition, six of seven patients had Gd-enhancing lesions that explained their clinical signs; in five of six of these patients, suppression of the Gd-enhanced lesions temporally correlated with clinical improvement. Thus, short courses of high-dose IV Mp suppress Gd enhancement in acute demyelinating lesions, and this correlates with clinical improvement.

Sneddon's disease presenting with visual loss and dementia.

A 51-year-old woman with Sneddon's disease presented with transient right hemifield loss of vision and transient right-sided weakness. Over the preceding decade she had experienced a slow decline in mental function. She also had hypertension, migraine, and a mixed seizure disorder. She had skin changes typical for generalized livedo reticularis but she did not have Raynaud's phenomenon or winter ulcerations. Her disease was not understood until the stroke-related symptoms were associated with the skin abnormalities. We review the neuro-ophthalmic manifestations of Sneddon's disease and add data from our case to the growing body of fact that suggests that Sneddon's disease may be an immunologically mediated vasculopathy.

Pulmonary effects of paraquat in the first day after injection.

To learn whether surface force changes precede the appearance of lung edema during experimental intoxication due to paraquat, we studied rats for 1 day following injection of 27 mg/kg iv. By 24 h, surface-active material recovered by lung lavage was decreased 32 percent, and changes in lung microsections and recoil pressure at half-deflation suggested decreased alveolar stability. Despite a 25 percent loss in overall body weight, lung weight increased more than 7 percent and protein concentration in lung lavage fluid increased by 158 percent. Lung edema was demonstrated morphologically as early as we could detect changes in surfactant or lung mechanical properties. Metabolic studies with lung tissue slices incubated with 4.5 times 10-4 M paraquat showed a fourfold increase in 14CO2 formed from (1-14C) glucose, but no significant change in 14CO2 form (6-14C) glucose, suggesting increased utilization of the pentose pathway for oxidation of glucose. (1-14C) Acetate oxidation was impaired slightly, but incorporation into lipid was decreased by 70 percent. we conclude that paraquat intoxication in the rat is not a suitable model for studying uncomplicated perturbation of the surfactant system.

Blood volume.

During the past decade the diagnostic use of blood volume determinations has declined as a result of the generation of largely inaccurate results and inappropriate normalization and interpretation. After historical development of more than 50 years, current methodology employs 125I-labeled human serum albumin and 51Cr-labeled red blood cells to determine plasma volume and red cell volume, respectively. Accurate blood volume determinations require (1) abandoning the use of the mean body hematocrit:venous hematocrit ratio and using simultaneous independent measurements of both volumes; (2) delaying multiple postinjection patient samples until complete mixing and equilibration are complete; (3) backextrapolation of plasma concentrations of 125I to account for albumin loss from the plasma, and, rarely, back-extrapolation of red cell concentrations to account for dilution by red cells transfused during the procedure; (4) normalization of volumes by adjusting patient weight to normal correspondence with lean tissue mass, whenever necessary. A rapid, routine method that fulfills these four requirements is presented. A number of surgical and medical conditions in which blood volume determinations are very useful in diagnosis and therapy are discussed. Recently developed techniques for blood volume measurements include neutron acativation analysis and fluorescent excitation analysis. Correct normalization of accurate blood volume measurements will provide a valuable service to the entire medical community.