Sclerotherapy, cryoablation, and surgical fixation of an intraosseous tibial venous malformation.

Intraosseous vascular malformations are rare vascular anomalies that present unique treatment challenges due to structural instability, embolization and sclerotherapy resistance, and tendency to recur. Patients may have clinical manifestations including pain, functional impairment, increased fracture risk, and decreased quality of life. Image-guided ablation techniques are emerging interventional treatment options for soft tissue tumors and complicated vascular anomalies. Percutaneous image-guided cryoablation offers a potential alternative as an isolated or adjunct therapy for intraosseous vascular malformations.

Characterization of Methyl- and Acetyl-Ni Intermediates in Acetyl CoA Synthase Formed during Anaerobic CO2 and CO Fixation.

The Wood-Ljungdahl Pathway is a unique biological mechanism of carbon dioxide and carbon monoxide fixation proposed to operate through nickel-based organometallic intermediates. The most unusual steps in this metabolic cycle involve a complex of two distinct nickel-iron-sulfur proteins: CO dehydrogenase and acetyl-CoA synthase (CODH/ACS). Here, we describe the nickel-methyl and nickel-acetyl intermediates in ACS completing the characterization of all its proposed organometallic intermediates. A single nickel site (Nip) within the A cluster of ACS undergoes major geometric and redox changes as it transits the planar Nip, tetrahedral Nip-CO and planar Nip-Me and Nip-Ac intermediates. We propose that the Nip intermediates equilibrate among different redox states, driven by an electrochemical-chemical (EC) coupling process, and that geometric changes in the A-cluster linked to large protein conformational changes control entry of CO and the methyl group.

Seeing the cis-Dihydroxylating Intermediate: A Mononuclear Nonheme Iron-Peroxo Complex in cis-Dihydroxylation Reactions Modeling Rieske Dioxygenases.

The nature of reactive intermediates and the mechanism of the cis-dihydroxylation of arenes and olefins by Rieske dioxygenases and synthetic nonheme iron catalysts have been the topic of intense research over the past several decades. In this study, we report that a spectroscopically well characterized mononuclear nonheme iron(III)-peroxo complex reacts with olefins and naphthalene derivatives, yielding iron(III) cycloadducts that are isolated and characterized structurally and spectroscopically. Kinetics and product analysis reveal that the nonheme iron(III)-peroxo complex is a nucleophile that reacts with olefins and naphthalenes to yield cis-diol products. The present study reports the first example of the cis-dihydroxylation of substrates by a nonheme iron(III)-peroxo complex that yields cis-diol products.

Vanadate Retention by Iron and Manganese Oxides.

Anthropogenic emissions of vanadium (V) into terrestrial and aquatic surface systems now match those of geogenic processes, and yet, the geochemistry of vanadium is poorly described in comparison to other comparable contaminants like arsenic. In oxic systems, V is present as an oxyanion with a +5 formal charge on the V center, typically described as H x VO4 (3-x)-, but also here as V(V). Iron (Fe) and manganese (Mn) (oxy)hydroxides represent key mineral phases in the cycling of V(V) at the solid-solution interface, and yet, fundamental descriptions of these surface-processes are not available. Here, we utilize extended X-ray absorption fine structure (EXAFS) and thermodynamic calculations to compare the surface complexation of V(V) by the common Fe and Mn mineral phases ferrihydrite, hematite, goethite, birnessite, and pyrolusite at pH 7. Inner-sphere V(V) complexes were detected on all phases, with mononuclear V(V) species dominating the adsorbed species distribution. Our results demonstrate that V(V) adsorption is exergonic for a variety of surfaces with differing amounts of terminal -OH groups and metal-O bond saturations, implicating the conjunctive role of varied mineral surfaces in controlling the mobility and fate of V(V) in terrestrial and aquatic systems.

Oxidation of V(IV) by Birnessite: Kinetics and Surface Complexation.

Vanadium is a redox-active metal that has been added to the EPA's Contaminant Candidate List with a notification level of 50 µg L-1 due to mounting evidence that VV exposure can lead to adverse health outcomes. Groundwater V concentration exceeds the notification level in many locations, yet geochemical controls on its mobility are poorly understood. Here, we examined the redox interaction between VIV and birnessite (MnO2), a well-characterized oxidant and a scavenger of many trace metals. In our findings, birnessite quickly oxidized sparingly soluble VIV species such as häggite [V2O3(OH)2] into highly mobile and toxic vanadate (HnVO4(3-n)-) in continuously stirred batch reactors under neutral pH conditions. Synchrotron X-ray absorption spectroscopic (XAS) analysis of in situ and ex situ experiments showed that oxidation of VIV occurs in two stages, which are both rapid relative to the measured dissolution rate of the VIV solid. Concomitantly, the reduction of birnessite during VIV oxidation generated soluble MnII, which led to the formation of the MnIII oxyhydroxide feitknechtite (ß-MnOOH) upon back-reaction with birnessite. XAS analysis confirmed a bidentate-mononuclear edge-sharing complex formed between VV and birnessite, although retention of VV was minimal relative to the aqueous quantities generated. In summary, we demonstrate that Mn oxides are effective oxidants of VIV in the environment with the potential to increase dissolved V concentrations in aquifers subject to redox oscillations.

Firing Increases Arsenic Leaching from Ceramic Water Filters via Arsenic and Iron Phase Transformations.

Ceramic water filters (CWFs) are produced globally using local clay sources and can effectively remove bacterial pathogens during point-of-use water treatment. The ceramic production process involves firing clay mixed with burnout material at temperatures of 800-1100 °C, which induces mineralogical changes leading to increased arsenic (As) leaching from CWF material compared to source clay. Unfired clay and fired CWFs from Cambodia, Canada, and Mexico, CWF from Laos, and test-fired clay from the United States were analyzed to determine the extent of As leaching from CWFs that range in As (<1 to 16 mg kg-1) and iron (Fe) (0.6 to 5%) content. Deionized water, NaOH, HCl, and oxalate extractions showed that firing increased As solubility and decreased Fe solubility compared to unfired clay, with up to 8 mg kg-1 of water-soluble As in Cambodian CWFs. X-ray absorption spectra of the Cambodian clay and CWF showed a decrease in the Fe-O distance from 2.01 to 1.91 Å and decreased Fe coordination number from 6.3 to 4.6 after firing, indicating a decrease in Fe-O coordination. Arsenic(V) was the dominant species in Cambodia clay and CWF, existing primarily as a surface complex with average As-Fe distance of 3.28 Å in clay while in CWF As was either an outer-sphere As(V) phase or a discrete arsenate phase with no significant As-Fe scattering contribution within the resolution of the data. Improved understanding of molecular-scale processes that cause increased As leaching from CWFs provides a basis for assessing As leaching potential prior to CWF factory capital investment as well as engineered solutions (e.g., modified firing temperature, material amendments, and leaching prior to distribution) to mitigate As exposure from CWFs.

Manganese, Arsenic, and Carbonate Interactions in Model Oxic Groundwater Systems.

Manganese and arsenic both threaten groundwater quality globally, but their chemical behavior leads to both co-contamination and separation of these contaminants from individual well to regional scales. Here we tested manganese and arsenic retention under conditions commonly found within aquifer redox fluctuating and transition zones where both arsenic and iron phases are present in oxidized forms, but manganese persists as reduced and soluble Mn(II). Analysis of column aqueous breakthrough data and characterization of solid-phase products using X-ray photoelectron (XPS) and absorption spectroscopies (XAS) show that the addition of bicarbonate increased manganese retention but decreased arsenic retention, while the presence of manganese and arsenic together increased both arsenic and manganese retention. In the presence of O2 arsenic remained oxidized as arsenate under all conditions measured; however, reduced Mn(II) was oxidized to an average Mn oxidation state of ∼3 in the absence of arsenate. The presence of arsenate partially inhibited Mn(II) oxidation likely by blocking ferrihydrite surfaces needed to catalyze Mn(II) oxidation by O2 and by stabilizing Mn(II) via ternary complex formation. These results highlight the interactions between reduced and oxidized contaminants that can contribute to the co-occurrence or physical separation of manganese and arsenic in groundwater systems under changing or stratified redox conditions.

Care for the underinsured: who should pay?

Inner-city medically underinsured adults describe their preferences for health care and willingness to pay for health care services. The responses of 146 patients attest to the burden of administrative and economic responsibility placed on the public health care sector for indigent patient care. The results of this survey address the information required by the nurse managers who must balance patient needs against administrative pressures to generate revenue from patient fees.

Teaching inner-city mothers about family planning and prenatal and pediatric services.

One hundred thirty-five young, black, inner-city, pregnant women assessed the usefulness of a videotape designed by community health nurses to increase the self-care practices of low-income minority women with regard to their prenatal, pediatric, and family planning health needs. Seventy percent of the women rated as very useful information on the availability of health care and the protocols of public health clinics. The women also stated that they would tell others about public health care services and intended to make use of these services themselves as a result of viewing the videotape. The viewers' responses help clarify the preferred modality, content, and length of patient education for medically and socioeconomically high-risk pregnant women who tend to underuse preventive and primary health care.

PIP: The improvement of health care facilities and delivery for indigent women and their children is of prime importance. As a result of improving health facilities, it is believed that an improvement will be made in infant and child health. The study was conducted in an inner- city area of 150,000 people; where the majority of families have single mothers as their head. The community is served by a community health center and 2 satellite clinics. The aim of the study was to provide a health education program which would explain the services of the clinic to new patients or to those persons not registered with a Department of Health (DOH) clinic. A sample population of 135 black inner-city; pregnant women viewed a videocassette entitled, "Making Healthy Choices" at the community health center and at a public high school. The videocassette provides 3 scenarios and solutions to each of the problems presented; however, the range of topics presented could be considered pertinent to each of the viewer's lives. The results of the study are as follows: over 50% of the women viewing the videocassette found the information "very useful"; however, when the group is broken down into those familiar with DOH services and those who are not, over 60% of the non-DOH women found the tape useful. When asked to identify the most frequent used service at the DOH, prenatal care and pediatric care were ranked 1st and 2nd, respectively. In addition to this, explanations on the length of pediatric care proved useful since length of time proved a deterrent to many mothers seeking child care.

Human trigeminal root evoked potentials during differential retrogasserian thermal and chemical rhizotomy.

Human trigeminal root evoked potentials have been recorded using signal averaging techniques during radiofrequency trigeminal rhizotomy and lidocaine blocks in patients with trigeminal neuralgia. Both short and long latency trigeminal root potentials have been recorded which appear to represent fast- and slow-conducting fiber activity respectively. Long latency trigeminal root potentials appear in recordings at the noxious threshold as perceived by the awake patient and are relatively selectively abolished in a reversible fashion by lidocaine block and irreversibly by radiofrequency heat. Evaluation of these trigeminal root potentials provides an objective assessment of the results of pain surgery directed at differential destruction of slow-conducting fiber activity.

Conducted somatosensory evoked potentials during spinal surgery. Part 1: control conduction velocity measurements.

Intraoperative recordings of conducted bipolar epidural somatosensory evoked potentials (SEP's) generated by unilateral common peroneal nerve stimulation have been obtained in 27 patients. The SEP's were multiphasic, 0.3 to 1.5 microV in amplitude, and recorded in 100% of patients with normal cords or in patients with spinal lesions, at a site caudal to the lesions. Control spinal conduction velocities (CV's), measured in the midthoracic to lower cervical regions, were in the range of 65 to 85 m/sec. Control lumbar and lower thoracic CV's were in the range of 30 to 45 m/sec. The CV values were obtained periodically throughout the course of surgery and were plotted as a function of time. In control patients with extradural lesions and neuroleptic anesthesia, the CV's remained constant (+/- 3%). The consistency, sensitivity, and safety of SEP recordings obtained by this technique make precise monitoring readily available during spinal operations.

Conducted somatosensory evoked potentials during spinal surgery. Part 2: clinical applications.

In 27 patients undergoing laminectomy, spinal cord function was monitored by epidural bipolar recordings of conducted spinal somatosensory evoked potentials (SEP's) across the laminectomy site, with calculation of spinal conduction velocity (CV). In control cases without myelopathy, the CV remained relatively constant (+/- 3%) even during prolonged operations, despite markedly changing levels of anesthesia. Acute CV changes were detected intraoperatively in three cases: these patients displayed improvement after extramedullary (Case 1) and intramedullary decompression (Case 2), and deterioration after direct unilateral dorsal column injury (Case 3). These intraoperative CV alterations correlated postoperatively with changes in the neurological examination. Although a unilateral lesion confined to the dorsal column abolished the ipsilateral SEP in Case 3, complete anterior quadrant lesions did not consistently change the CV (Case 4). This further suggests that the SEP is generated entirely by ipsilateral dorsal column activation. Accurate measurement of this dorsal column conduction velocity across the operative field provides a very sensitive means of monitoring spinal cord function during operations for neurosurgical spinal lesions.

Treatment of trigeminal neuralgia and other facial pains by retrogasserian injection of glycerol.

Håkanson's treatment of trigeminal neuralgia by injecting 0.2 to 0.4 ml of glycerol into the cerebrospinal fluid in Meckel's cave was carried out in 27 patients with trigeminal neuralgia, 3 with atypical facial neuralgia, and 1 with post-traumatic facial neuralgia. Minor modifications of his technique are described based on our finding of a greater pain and sensory loss upon injection than he noted. We present evidence that glycerol is more toxic than its cryoprotectant effect would intimate and that it selectively eliminates those components of the compound action potential in the trigeminal rootlets customarily associated with pain. We conclude that the method is probably going to be an improvement over radiofrequency heating for the treatment of trigeminal neuralgia in many situations.

Synaptic connexions of two symmetrically placed giant serotonin-containing neurones.

1. Each giant serotonin cell in Helix pomatia makes synaptic connexions with three non-amine-containing neurones: the anterior, middle and posterior buccal cells.2. Individual e.p.s.p.s, of 500-600 msec duration, were observed in both left and right middle cells following each evoked giant serotonin cell action potential. They were facilitated with repetitive stimulation of the giant serotonin cells and summed to give rise to an action potential. The membrane resistance of the middle cells was reduced when the giant serotonin cells were stimulated to fire rapidly. Evidence is presented which suggests that the link between each giant serotonin cell and each middle cell is monosynaptic.3. Iontophoretically applied serotonin produced a depolarizing potential change in the middle cell perikaryon; the response rapidly desensitized on repetitive application.4. Morphine abolished reversibly the middle cell serotonin potential and antagonized transmission from the giant serotonin cells to the middle cells. Lowering the Na concentration of the medium reversibly diminished the size of the serotonin potential and the giant serotonin cell elicited e.p.s.p.s in the middle cells.5. Reserpine, which depletes serotonin in the giant serotonin cell, impaired transmission from these cells to the middle cells.6. The results suggest that serotonin is the synaptic transmitter released from the giant serotonin cells on to the middle cells and that this system is a suitable model for further analysis of the neuronal role of serotonin.