Synthesis and Structure of Some MII/MIII Mixed Fluorides with Pyrochlore and Weberite Related Structures

New NH4MIIMIIIF6 and MIIMIIIF5 ・ 2H2O compounds with the pyrochlore and weberite structures, respectively, are reported. Structures of NH4CoCrF6, AlZnF5 ・ 2H2O, and GaMnF5 ・ 2H2O were refined using X-ray diffraction data from single crystals. The structures of MgIIAlIIIF5 ・H2O and NH4MgIIAlIIIF6 were refined from powder X-ray diffraction data. Magnetic susceptibility data indicates antiferromagnetic ordering in NH4CoIIVIIIF6 at 7 K but no ordering in NH4CoIICrIIIF6 down to 4.2 K. Electrical conductivity presumably due to protons was observed in MgAlF5 ・ (H2O)2.

New A2/3-xRh2O4 compounds with the CaFe2O4 structure where A is a rare earth or Bi

New compounds of the type R(2/3-x)Rh(2)O(4) with the CaFe(2)O(4) structure have been prepared, where R is a rare earth. For crystals grown in a Bi/V/O flux, the rare earth was partially replaced by Bi. No evidence of ordering of the A cation vacancies is found, but the A cations are displaced from the ideal A cation site by about 0.24 A. Electrical conductivity measurements on crystals suggest that the materials are degenerate semiconductors with Seebeck measurements showing p-type behavior. This is consistent with our observation that x in R(2/3-x)Rh(2)O(4) ranges up to about 0.09. The compounds were also characterized by magnetic susceptibility and diffuse reflectance measurements.

Nutritional assessment: its role in the provision of nutritional support

Generalised undernutrition is common in hospital patients and in the community. It is frequently unrecognised and is associated with a range of adverse consequences that contribute to increased morbidity and mortality. The National Institute for Health and Clinical Excellence recommends that all individuals engaging with healthcare or admitted to residential homes in the community should be screened for undernutrition. Laboratory investigations have little place in the diagnosis of undernutrition: this is primarily a clinical process. In particular, the measurement of serum albumin concentration, though widely promulgated in the past as an index of nutritional status, is worthless for this purpose. Laboratory investigations are, however, of importance: to diagnose specific nutritional deficiencies (eg, of trace elements) and to monitor the provision of nutritional support, to detect metabolic complications and to assess its adequacy (for which the measurement of serum prealbumin concentrations, particularly in conjunction with measurements of C-reactive protein, may be of value).

Electron-transfer salts of 1,2,3,4,5-pentamethylferrocene, Fe(II)(C5Me5)(C5H5). Structure and magnetic properties of two 1:1 and two 2:3 Fe(C5Me5)(C5H5) electron-transfer salts of tetracyanoethylene

The reaction of Fe(II)(C5Me5)(C5H5), FeCpCp, with percyano acceptors, A [A = C4(CN)6 (hexacyanobutadiene), TCNQF4 (perfluoro-7,7,8,8-tetracyano-p-quinodimethane), and DDQ (2,3-dichloro-5,6-dicyanobenzoquinone)], results in formation of 1:1 charge-transfer salts of [Fe(III)CpCp]*]*+[A]*- composition. With A = TCNQ (7,7,8,8-tetracyano-p-quinodimethane) a 1:2 electron-transfer salt with FeCpCp forms. With A = TCNE (tetracyanoethylene) a pair of 1:1 salts as well as a pair of 2:3 salts of [FeCpCp]2[TCNE]3.S (S = CH2Cl2, THF) have been isolated and characterized by single-crystal X-ray diffraction. [FeCpCp][TCNE] consists of parallel 1-D.D(*+)A(*-)D(*+)A(*-)D(*+)A(*-). chains, while [FeCpCp][TCNE].MeCN has a herringbone array of D(*+)A2(2-)D(*+) dimers separated by solvent molecules. Although each [TCNE](-) is disordered, the diamagnetic [TCNE]2(2-) dimer is structurally different from those observed earlier with an intradimer separation of 2.79 A. The [TCNE](-) in the 2:3 [FeCpCp]2[TCNE]3.S exists as an eclipsed diamagnetic [TCNE]2(2-) dimer with an intradimer ethylene C.C separation of 2.833 and 2.903 A for the CH2Cl2- and THF-containing materials, respectively. The bond distances and angles for all the cations are essentially equivalent, and the distances are essentially equivalent to those previously reported for [FeCp2](*+) and [FeCp2](*+) cations. The average Fe-C5H5-ring and Fe-C5Me5-ring centroid distances are 1.71 and 1.69 A, respectively, which are 0.05 A longer than reported for Fe(II)CpCp. The one-electron reduction potential for Fe(II)CpCp is 0.11 V (vs SCE). The 5 K EPR of [FeCpCp](*+)[BF4](-) exhibits an axially symmetric powder pattern with g(parallel) = 4.36 and g(perpendicular) = 1.24, and the EPR parameters are essentially identical to those reported for ferrocenium and decamethylferrocenium. The high-temperature magnetic susceptibility for polycrystalline samples of these complexes can be fit by the Curie-Weiss law, chi = C/(T - theta), with low theta values and mu(eff) values from 2.08 to 3.43 mu(B), suggesting that the polycrystalline samples measured had varying degrees of orientation. [FeCpCp][TCNE] exhibits the highest effective moment of 3.43 mu(B)/Fe and weak ferromagnetic coupling, as evidenced from the theta of 3.3 K; however, unexpectedly, it does not magnetically order above 2 K. The formation of the four phases comprising FeCpCp and TCNE emphasizes the diversity of materials that may form and the present inability to predict neither solid-state compositions nor structure types.

Provision of interpretative comments on biochemical report forms

Providing interpretative comments on reports, particularly those for primary care physicians is an important part of our job. Few clinical biochemists (whether medical or scientific) receive significant training for this. Most work in isolation, and few receive feedback on the utility of their comments. Surveys show an extremely wide divergence of opinion and comment even on apparently straightforward sets of abnormal results. Some comments are regarded as highly inappropriate when assessed by peer review. There is a need for further education and training in this area, concentrating as much on 'how to comment' as on 'what to comment'. There is also a need to establish some form of quality assurance for this important part of the post-analytical phase. A pilot External Quality Assurance Scheme (EQAS) is now being established.

Synthesis and structural analysis of the active enantiomer of famoxadone, a potent inhibitor of cytochrome bc1

Famoxadone is a newly commercialized fungicide and potent Qo-site inhibitor of cytochrome bc1. The S-(-)-enantiomer of famoxadone (the active component) was synthesized by two routes and was analyzed computationally and by X-ray crystallography. The molecule displays an extended conformation with flexibility in the structure imparted by the two terminal phenyl groups. In the crystal lattice, intermolecular hydrogen bonds occur between the NH and the oxygen atoms of the heterocycle.

Log-jam in acid-base education and investigation: why make it so difficult?

Medical students frequently have difficulty in interpreting acid-base data particularly when pH values are used. The difficulty persists when students qualify and has implications for the safe management of patients who require investigation of acid-base status. Simplification of tuition is required together with a change of practice in the reporting of acid-base data by the laboratories. To improve understanding, we recommend that the teaching and reporting of acid-base status should be changed to use [H+] instead of pH, and a greater emphasis placed on the logical interpretation of primary measurements--that is [H+] and PCO2--with less reliance on derived variables.

Aortoventricular fistula secondary to blunt trauma: a case report and review of the literature

An aorto-right ventricular fistula secondary to nonpenetrating trauma is described. Review of the literature is reported. Ascending aortic injuries present as either traumatic pseudoaneurysms or, less commonly, as aortocardiac fistulas. Blunt cardiac injury is a frequent concomitant injury and contributes to the high mortality of this lesion. Prompt surgical intervention is required for survival.

Laser hazard evaluation method for middle infrared laser systems

Hazard evaluation methods for lasers, with wavelengths greater than 1.4 microns (mostly in the middle infrared), have changed significantly in the current version of the American National Standard for the Safe Use of Lasers, ANSI Z136.1-1993. A correct evaluation involves comparing the hazard potential based on two evaluation models; one based on individual pulses and the other based on an equivalent continuous-wave exposure. An example of the hazard evaluation method within this spectral region is provided.

Colossal Magnetoresistance Without Mn3+/Mn4+ Double Exchange in the Stoichiometric Pyrochlore Tl2Mn2O7

Structural analysis from powder neutron and single-crystal x-ray diffraction data for a sample of the Tl2Mn2O7 pyrochlore, which exhibits colossal magnetoresistance (CMR), shows no deviations from ideal stoichiometry. This analysis gives an Mn-O distance of 1.90 angstroms, which is significantly shorter than the Mn-O distances (1.94 to 2.00 angstroms) observed in phases based on LaMnO3 perovskites that exhibit CMR. Both results in Tl2Mn2O7 indicate oxidation states very close to Tl23+Mn24+O7. Thus, Tl2Mn2O7 has neither mixed valence for a double-exchange magnetic interaction nor a Jahn-Teller cation such as Mn3+, both of which were thought to have an important function in CMR materials. An alternate mechanism for CMR in Tl2Mn2O7 based on magnetic ordering driven by superexchange and strong spin-fluctuation scattering above the Curie temperature is proposed here.

Heterotopic bone formation within a missile track

A case is presented which is thought to be the first described example of heterotopic ossification occurring within the path of a bullet. Although the information was not available from prior medical records, the bullet presumably passed though bone or periosteum, thereby seeding the permanent cavity and facilitating ossification within the surrounding muscle and soft tissue.

Rupture of the deep femoral artery from blunt trauma

Massive hemorrhage from the deep femoral artery is an uncommon entity in the setting of blunt extremity trauma without femur fracture. A case of deep femoral artery injury causing massive hemorrhage treated by angiographic embolization is reported. In this patient, persistent unexplained hypotension warranted angiographic analysis of a pelvic fracture. Because of a swollen right thigh, the negative pelvic angiogram was extended to include the lower extremity, confirming the diagnosis of a ruptured branch of the deep femoral artery. Bleeding was controlled with embolization that promptly resolved the patient's hemodynamic instability. The salient feature in common with previous reported cases of deep femoral artery injury was hemodynamic instability beyond accountable blood loss. We recommend angiographic analysis with radiological and surgical intervention in the setting of thigh swelling without femur fracture and unexplained hypotension. This management strategy was well tolerated, and the patient received minimal transfusions.

Comparative hazard evaluation of near-infrared diode lasers

Hazard evaluation methods from various laser protection standards differ when applied to extended-source, near-infrared lasers. By way of example, various hazard analyses are applied to laser training systems, which incorporate diode lasers, specifically those that assist in training military or law enforcement personnel in the proper use of weapons by simulating actual firing by the substitution of a beam of near-infrared energy for bullets. A correct hazard evaluation of these lasers is necessary since simulators are designed to be directed toward personnel during normal use. The differences among laser standards are most apparent when determining the hazard class of a laser. Hazard classification is based on a comparison of the potential exposures with the maximum permissible exposures in the 1986 and 1993 versions of the American National Standard for the Safe Use of Lasers, Z136.1, and the accessible emission limits of the federal laser product performance standard. Necessary safety design features of a particular system depend on the hazard class. The ANSI Z136.1-1993 standard provides a simpler and more accurate hazard assessment of low-power, near-infrared, diode laser systems than the 1986 ANSI standard. Although a specific system is evaluated, the techniques described can be readily applied to other near-infrared lasers or laser training systems.

The role of diagnostic laparoscopy in the management of trauma patients: a preliminary assessment

This study evaluated the role and advantages of diagnostic laparoscopy (DL) compared with diagnostic peritoneal lavage (DPL) in 75 trauma patients who were prospectively studied with DL followed by DPL. Of these, 59 patients had blunt injuries and 16 stab wounds. Seventy patients (93%) had the procedures performed in the emergency department (ED); 41 (59%) of these were awake and under local anesthesia. Forty-two patients had negative DPL and DL results with no subsequent sequelae. Twenty-three patients had negative DPL results and abnormal DL results. Of these, 20 were managed nonsurgically, and three (DPL < 10,000 RBC) underwent surgery based solely on DL findings of diaphragmatic lacerations from stab wounds. These were repaired. All 23 had an uneventful course. Three patients had positive DPL and insignificant DL findings. Laparotomy and DL findings correlated. A splenectomy for iatrogenic injury unrelated to DL and two nontherapeutic laparotomies were performed. Seven patients demonstrated both positive DPL and significant DL findings, and all had therapeutic laparotomies. Management based on DL rather than DPL would potentially have improved care in 8% of cases (6 of 75). Reliance on DL improved care in 19% (3 of 16) of patients with stab wounds and possibly could have in 3% (2 of 59) of those with blunt injuries. Management using DL would have potentially improved care in 30% (3 of 10) of patients with positive DPL findings and 5% (3 of 65) with negative DPL findings. Diagnostic laparoscopy can be performed safely in stable patients under local anesthesia in the ED. It offers no advantage over DPL as a primary assessment tool in blunt trauma. It does have advantages in the management of stab wounds. Diagnostic laparoscopy has a role in redefining DPL criteria for laparotomy and, in selected patients, as an adjunct to DPL, allowing further diagnosis and potentially the treatment of injuries without laparotomy.

Neuromuscular blockade in aeromedical airway management

STUDY OBJECTIVE

Induction of paralysis before intubation is controversial in the aeromedical setting. We reviewed our experience using neuromuscular blockade with nurse/paramedic aeromedical teams to determine effectiveness and outcome.

MATERIALS AND METHODS

In 670 flights during a 16-month period, 119 patients required endotracheal intubation aided by muscle relaxant administration. Age ranged from two months to 83 years, with a mean of 33 years. All patients were hyperventilated with 100% oxygen before intubation. Sedation was given if presenting systolic blood pressure was greater than 100 mm Hg. A short-acting depolarizing agent was then given in a 1-mg/kg dose. Once the airway was secure, a longer-acting, nondepolarizing agent and/or sedation was given.

RESULTS

Of the 119 patients, 115 (96.6%) were orally intubated. Four (3.4%) required surgical airway intervention because of injuries and conditions prohibiting oral intubation. Of 115 oral intubations, 99 (86%) were achieved on the first attempt. Eight patients (7%) were intubated on a second attempt, and another eight were intubated on a third attempt. There was no change in operator. Sixty-eight percent of patients requiring airway management were multiple trauma victims with associated head injuries. There were no laryngeal injuries, detected cardiac rhythm changes, bleeding episodes, or neurologic complications despite incomplete cervical-spine evaluation.

CONCLUSION

Neuromuscular blockade can be used safely and effectively in the field by experienced nurse/paramedic teams. Although problematic intubation was not eliminated, the difficulties encountered were manageable and the overall risk/benefit ratio was acceptable.

Introduction of pulse oximetry in the air medical setting

The importance of adequate oxygenation in critically ill patients is widely recognized. Pulse oximetry (PO) is a non-invasive, rapid technique of arterial hemoglobin oxygen saturation (SaO2) measurement. This report is a review of our experience using the PO during air medical transport. A chart review was conducted on patients who used air medical transport between October 1988 and March 1989. Types of patients included trauma and ICU patients who were transported from either accident scenes or outlying hospitals. SaO2 and vital sign (VS) measurements were obtained pre and postflight, and inflight interventions were documented. Four groups of patients were identified: Group 1: PO used, inflight intervention employed; Group II: PO used, no inflight intervention employed; Group III: no PO used, inflight intervention employed; Group IV: no PO used, no inflight intervention employed. A dependent, paired-t-test was used to compare pre and postflight SaO2 and VS measurements. The mean difference between pre and postflight measurements of SaO2, systolic blood pressure, and pulse rate were calculated within each group. Then, an ANOVA with post-hoc Newman-Keuls Test compared the means between the four groups. Of the 137 patients reviewed, 82 used PO and 55 patients did not due to technical or anatomic problems. Of the 82 patients who used PO, 19 received an inflight intervention.(ABSTRACT TRUNCATED AT 250 WORDS)

Air medical response to the 1990 Will County, Illinois, tornado

At least 29 people were killed and over 300 injured on August 28, 1990, when a powerful tornado cut a path of destruction through the outskirts of Chicago. The tornado's destructive force began a mammoth rescue effort from over 50 emergency medical service agencies, 80 ambulances, 1,000 rescue personnel, and Chicago's two air medical helicopters. The EMS effort was supplemented by an equally large response from police, fire, heavy rescue, K-9, and other emergency teams across north and central Illinois. Medical mass casualty incident procedures were activated and coordinated through the Will-Grundy Emergency Medical Services System, located at Silver Cross Hospital in Joliet. The towns of Crest Hill, Plainfield, and Joliet were the hardest hit, with more than $200 million in damages. The tornado strained not only the ground-based EMS and rescue systems, but taxed the resources of the city's air medical programs as well. This paper reviews the response by critical care air medical transport teams to this natural disaster.

Plasma uric acid in patients receiving anticonvulsant monotherapy

In newly diagnosed adult patients with epilepsy followed prospectively on monotherapy, carbamazepine and phenytoin were associated with a fall in plasma uric acid, but sodium valproate and phenobarbitone were associated with a rise in plasma uric acid. The mechanisms and significance of these findings are discussed.

Determining hazard distances from non-Gaussian lasers

A simple method is presented for determining the nominal ocular hazard distance from non-Gaussian laser beams. The simplified method currently used for laser safety calculations when determining the laser beam diameter as a function of distance produces errors in the near field. The irradiance or radiant exposure of multimode and non-Gaussian laser beams in the near field may be calculated more precisely by the use of a simple proposed relationship with easily determined parameters.

Synchronized independent lung ventilation in the management of pediatric unilateral pulmonary contusion: case report

Utilizing a double-lumen endobronchial tube, synchronized independent lung ventilation (SILV) was successfully employed to manage severe unilateral pulmonary contusion in a 6-year old trauma patient. This appears to represent the youngest reported patient in whom this technique has been utilized. Early institution of this treatment modality may substantially increase survival.

Frequency of pancreatitis in fulminant hepatic failure using isoenzyme markers

Evidence of acute pancreatitis was sought in 35 patients with fulminant hepatic failure. Total amylase was raised in 22 patients and isoenzyme separation showed a distinct P3 isoenzyme (indicative of pancreatitis) in 14. In four patients with marked hyperamylasaemia (greater than 1000 U/l) the predominant isoenzyme was the salivary fraction. Pancreatic lipase was abnormally raised (greater than 200 U/l) in 34 patients but exceeded 1000 U/l in 12 of the 14 with a distinct P3 isoenzyme. Thus on the basis of a distinct P3 isoenzyme of amylase and an increased pancreatic lipase activity evidence of pancreatitis was found in 34% of patients in this series.

Leukopenia secondary to silver sulfadiazine: frequency, characteristics and clinical consequences

Leukopenia associated with silver sulfadiazine (SSD) is a frequent event and may be a risk factor for infectious complications in the burn patient. This study reviews 77 patients with thermal injuries to determine total body surface area (BSA) burned, and white blood cell count (WBC) at time of hospital admission. A subpopulation of 56 patients with serial WBC counts were evaluated to determine lowest WBC count, topical burn therapy, episodes of infection or septic shock and final outcome. There was not a significant incidence of leukopenia on admission. Fifty-six per cent of patients treated with SSD and 12 per cent of silver nitrate-treated patients became leukopenic (P less than .05). The leukopenia was higher among SSD-treated patients who had greater than 15 per cent BSA burns (P less than .05). The onset of leukopenia generally occurred the second day after the burn and the WBC count returned to normal with discontinuance of the drug. The leukopenia was due primarily to a marked decrease in the number of mature neutrophils. There was no difference in the incidence of septic complications or opportunistic infections in the treatment groups. There was no significant difference in final outcome. Silver sulfadiazine-induced leukopenia appears to be a self-limited phenomenon that does not increase the incidence of infectious complications nor affect final outcome.

Total parenteral nutrition and the clinical chemistry laboratory

Parenteral nutrition is a well-established technique for feeding patients with intestinal failure and other conditions which render enteral feeding impossible. Biochemical tests are required in the initial assessment of these patients, for monitoring their response to treatment and for the detection and management of complications. The use of these tests is discussed critically and guidelines are provided for the frequency with which they should be performed. Chemical pathologists and clinical biochemists have an important role in the provision of parenteral nutrition as members of multi-disciplinary nutrition teams.

Osteopenia in systemic mastocytosis: natural history and responses to treatment with inhibitors of bone resorption

Studies of a 63-year-old woman with osteopenia due to systemic mastocytosis are reported. Delay in making the diagnosis and the occurrence of coincident medical problems meant that radiographs during a 12-year period were available for study. Skeletal symptoms began 20 years after the skin lesions of mastocytosis first appeared, but once established bone loss was rapid, particularly from cortical bone (estimated at 3.75% pa). Biochemical and histological measurements indicated a "high turnover" bone disease and treatment with inhibitors of bone resorption was assessed. Oral, but not intravenous, clodronate was effective in reducing bone turnover as judged by falls in hydroxyproline excretion (p less than 0.01) and serum alkaline phosphatase (p less than 0.01). Mithramycin and chlorambucil were ineffective. Clodronate may be beneficial in arresting bone loss in this disorder.

A new prognostic index in surgery and parenteral feeding: the ratio of triiodothyronine to reverse triiodothyronine in serum (T3/rT3 ratio)

Serum concentrations of albumin, triiodothyronine (T3), and reverse triiodothyronine (rT3) were measured in 46 patients on the first day after routine gastrointestinal surgery, and the molar ratio T3/rT3 was calculated. The median value of this ratio, but not of albumin, was significantly lower in 11 who subsequently suffered major septic complications than in the remainder. Measurement of the ratio correctly predicted the outcome of 80% of individuals. The T3/rT3 ratio, midarm muscle circumference (MAMC), triceps skin fold (TSF) and serum concentrations of albumin and transferrin were measured in 23 patients at referral for parenteral feeding. Median values of T3/rT3 ratio, MAMC and transferrin, but not of the other parameters, were significantly lower in nine who died than in survivors. Measurements of the ratio, MAMC and transferrin correctly predicted the outcome of 87%, 78% and 74% of individuals, respectively.

Diltiazem: dose it affect vasospasm?

Calcium antagonists are being investigated for their role in preventing or ameliorating the vasospasm associated with subarachnoid hemorrhage. We have done a phase I and phase II type trial of diltiazem. No effect on spasm was documented. A tendency to increase the bleeding time was noted, but no detrimental clinical effect occurred. The rebleed rate was not changed. It appears that further study of diltiazem through a proper randomized study would not be cost- or time-effective.

Current clinical laboratory practice: investigation of plasma lipids--which tests and when?

Clinical interest in the lipoproteins stems mainly from the association between serum cholesterol concentrations and coronary heart disease. Investigations of lipoproteins should be performed in patients with premature coronary heart disease, with a strong family history of coronary heart disease, or with certain cutaneous stigmata of hyperlipoproteinaemia and when fasting serum samples are seen to be lipaemic. Family studies should be performed in appropriate cases to identify relatives at increased risk of developing coronary heart disease. Patients with conditions known to cause secondary hyperlipoproteinaemia should be investigated if they fall into one of these categories but only after treatment of the underlying condition. Non-specialist laboratories should be able to measure total cholesterol and triglyceride concentrations and high density lipoprotein cholesterol concentrations. Lipoprotein electrophoresis has a limited role in such laboratories and is not necessary as a routine procedure. Specialist laboratories should in addition be able to measure individual lipoproteins and identify apolipoprotein E phenotypes.