Intra-and inter-reader reliability of semi-automated quantitative morphometry measurements and vertebral fracture assessment using lateral scout views from computed tomography

Intra-and inter-reader reliability of semi-automated quantitative vertebral morphometry measurements was determined using lateral computed tomography (CT) scout views. The method requires less time than conventional morphometry. Reliability was excellent for vertebral height measurements, good for height ratios, and comparable to semi-quantitative grading by radiologists for identification of vertebral fractures.

INTRODUCTION

Underdiagnosis and undertreatment of vertebral fracture (VFx) is a well-known problem worldwide. Thus, new methods are needed to facilitate identification of VFx. This study aimed to determine intra- and inter-reader reliability of semi-automated quantitative vertebral morphometry based on shape-based statistical modeling (SpineAnalyzer, Optasia Medical, Cheadle, UK).

METHODS

Two non-radiologists independently assessed vertebral morphometry from CT lateral scout views at two time points in 96 subjects (50 men, 46 women, 70.3 ± 8.9 years) selected from the Framingham Heart Study Offspring and Third Generation Multi-Detector CT Study. VFxs were classified based solely on morphometry measurements using Genant's criteria. Intraclass correlation coefficients (ICCs), root mean squared coefficient of variation (RMS CV) and kappa (k) statistics were used to assess reliability.

RESULTS

We analyzed 1,246 vertebrae in 96 subjects. The analysis time averaged 5.4 ± 1.7 min per subject (range, 3.2-9.1 min). Intra-and inter-reader ICCs for vertebral heights were excellent (>0.95) for all vertebral levels combined. Intra-and inter-reader RMS CV for height measurements ranged from 2.5% to 3.9% and 3.3% to 4.4%, respectively. Reliability of vertebral height ratios was good to fair. Based on morphometry measurements alone, readers A and B identified 51-52 and 46-59 subjects with at least one prevalent VFx, respectively, and there was a good intra-and inter-reader agreement (k = 0.59-0.69) for VFx identification.

CONCLUSIONS

Semi-automated quantitative vertebral morphometry measurements from CT lateral scout views are convenient and reproducible, and may facilitate assessment of VFx.

Evaluation of mass spectrometric methods for detection of the anti-protozoal drug imidocarb

Imidocarb [N,N'-bis[3-(4,5-dihydro-1H-imidazol-2-yl)phenyl]urea, C(19)H(20)N(6)O(1), m.w. 348.41] is a symmetrical carbanilide derivative used to treat disease caused by protozoans of the Babesia genus. Imidocarb, however, is also considered capable of suppressing Babesia-specific immune responses, allowing Babesia-positive horses to pass a complement fixation test (CFT) without eliminating the infection. This scenario could enable Babesia-infected horses to pass CFT-based importation tests. It is imperative to unequivocally identify and quantify equine tissue residues of imidocarb by mass spectrometry to address this issue. As a pretext to development of sensitive tissue assays, we have investigated possibilities of mass spectrometric (MS) detection of imidocarb. Our analyses disclosed that an unequivocal mass spectral analysis of imidocarb is challenging because of its rapid fragmentation under standard gas chromatography (GC)-MS conditions. In contrast, solution chemistry of imidocarb is more stable but involves distribution into mono- and dicationic species, m/z 349 and 175, respectively, in acid owing to the compound's inherent symmetrical nature. Dicationic imidocarb was the preferred complex as viewed by either direct infusion-electrospray-MS or by liquid chromatography (LC)-MS. Dicationic imidocarb multiple reaction monitoring (MRM: m/z 175 → 162, 145, and 188) therefore offer the greatest opportunities for sensitive detection and LC-MS is more likely than GC-MS to yield a useful quantitative forensic analytical method for detecting imidocarb in horses.

Variability in the biological response to anti-CD20 B cell depletion in systemic lupus erythaematosus

OBJECTIVE

To study the effects in systemic lupus erythaematosus (SLE) of B cell directed therapy with rituximab, a chimeric monoclonal antibody directed at CD20+ B cells, without concomitant immunosuppressive therapy in mild to moderate SLE.

METHODS

Patients (n=24) with active SLE and failure of >or=1 immunosuppressive were recruited from three university centres into this phase I/II prospective open-label study. Patients were followed for 1 year to assess safety, efficacy and biological effects.

RESULTS

In total, 18 of the patients scheduled to receive the full lymphoma dose of rituximab were evaluable for B cell levels in peripheral blood. Of these, 17 had effective CD19+ B cell depletion (<5 cells/microl). However, six of the depleted patients showed B cell return before 24 weeks. A total of 70% of patients improved by week 55, as defined by an SLE Disease Activity Index (SLEDAI) score improvement of >or=2 units from baseline. The degree of CD19+ B cell depletion was correlated with SLEDAI improvement at week 15 (r=0.84). In general, rituximab infusions were well tolerated. Approximately a third of the patients developed human anti-chimeric antibody (HACA) titres, which correlated with poor B cell depletion. Most patients (9 of 14) did not respond to immunisations with Pneumovax and tetanus toxoid.

CONCLUSIONS

Rituximab is a promising new therapy for SLE. The variability of responses in patients with SLE may be related to HACA formation. The failure to respond to immunisations is surprising, in view of the apparently low risk of infections. Better biological markers are necessary to follow these patients during treatment.

Benign metastasizing leiomyoma: clinical, imaging, and pathologic correlation

OBJECTIVE

We describe the clinical presentation and the radiographic and CT findings of benign metastasizing leiomyoma.

CONCLUSION

Benign metastasizing leiomyoma is an asymptomatic disease characterized by well-defined, numerous, pulmonary lesions without a preponderant distribution.

Syntheses and structural characterization of luminescent platinum(II) complexes containing di-tert-butylbipyridine and new 1,1-dithiolate ligands

Three new di-tert-butylbipyridine (dbbpy) complexes of platinum(II) (1-3) containing 1,1-dithiolate ligands have been synthesized and characterized. The 1,1-dithiolates are 2,2-diacetylethylene-1,1-dithiolate (S(2)C=C(C(O)Me)2) (1), 2-cyano-2-p-bromophenylethylene-1,1-dithiolate (S(2)C=C(CN)(p-C(6)H(4)Br)) (2), and p-bromophenyl-2-cyano-3,3-dithiolatoacrylate (S(2)C=C(CN)(COO-p-C(6)H(4)Br)) (3). Complex 1 exhibits a solvatochromic charge-transfer absorption in the 430-488 nm region of the spectrum and a luminescence around 635 nm in ambient temperature CH(2)Cl(2) solution. These observations are consistent with what has been seen previously in related Pt diimine 1,1-dithiolate complexes. The nature of the emissive state is assigned as a (3)(mixed metal/dithiolate-to-diimine) charge transfer, while the solvatochromic absorption band corresponds to the singlet transition of similar orbital character. The other complexes also exhibit a low-energy solvatochromic absorption. The crystal structures of two of the complexes have been determined, representing the first time that Pt(diimine)(1,1-dithiolate) complexes have been crystallographically studied. The structures confirm the expected square planar coordination geometry with distortions in bond angles dictated by the constraints of the chelating ligands. The Pt-S and Pt-N bond lengths and S-Pt-S and N-Pt-N bond angles for the two structures are identical within experimental error (2.283(2) and 2.278(2) A; 2.053(6) and 2.050(8) A; 75.01(8) degrees and 75.40(8) degrees; 79.2(2) degrees and 79.0(2) degrees, respectively). Crystal data for 1: monoclinic, space group P2(1)/n (No. 14), with a = 7.20480(10) A, b = 20.53880(10) A, c = 19.1072(2) A, beta = 93.83 degrees, V = A(3), Z = 4, R1 = 3.34% (I > 2sigma(I)), wR2 = 9.88% (I > 2sigma(I)) for 3922 unique reflections. Crystal data for 2: monoclinic, space group P2(1)/n (No. 14), with a = 15.0940(5) A, b = 9.5182(3) A, c = 20.4772(7) A, beta = 111.151(1) degrees, V = A(3), Z = 4, R1 = 4.07% (I > 2sigma(I)), wR2 = 8.64% (I > 2sigma(I)) for 3859 unique reflections.

A gold(I) mononuclear complex and its association into binuclear and cluster compounds by hydrogen bonding or metal ion coordination

The mononuclear Au(I) complex, Au(Spy)(PPh2py) (1), has been synthesized and characterized structurally. The complex possesses the expected linear coordination geometry with a S-Au-P bond angle of 176.03(6) degrees and no evidence of aurophilic interactions between nearest neighbor Au(I) ions in the solid state. Protonation of the pendant pyridyl groups of 1 leads to the formation of the H-bonded dimer [(Au(SpyH)(PPh2py))2](PF6)2 (2), which has also been structurally characterized. A linear coordination geometry at the Au(I) ions in 2 with a S-Au-P bond angle of 173.7(2) degrees is augmented by evidence of a strong aurophilic interaction with a Au...Au distance of 2.979(1) A. The pendant pyridyl groups of 1 have also been used to bind Cu(I) by reactions with [Cu(NCMe)4](PF6) and Cu(P(p-tolyl)3)2(NO3) leading to the formation of the heterobimetallic complexes [(AuCu(mu-Spy)(mu-PPh2py))2](PF6)2 (3) and [AuCu(P(p-tolyl)3)2(mu-Spy)(mu-PPh2py)](NO3) (4), respectively. A structure determination of 3 reveals a tetranuclear complex composed of two AuCu(mu-Spy)(mu-PPh2py)+ units held together by bridging thiolate ligands. A strong metal-metal interaction is noted between the two different d10 ions with nearest Au-Cu distances averaging 2.6395 A. The S-Au-P bond angles in 3 deviate slightly from linearity due to the Au...Cu interactions, while the coordination geometries at Cu(I) are distorted tetrahedral consisting of the two pyridyl nitrogen atoms, a bridging thiolate sulfur, and the interacting Au(I) ion. While mononuclear complex 1 is only weakly emissive in the solid state and in fluid solution, complexes 2-4 show stronger photoluminescence in the solid state and rigid media at 77 K, and in fluid solution. The emission maxima for 2-4 in ambient temperature fluid solution are 470, 635, and 510 nm, respectively. A tentative assignment of the emitting state as a S(p pi)-->Au LMCT transition is made on the basis of previous studies of Au(I) thiolate phosphine complexes. Shifts of lambda em result from the influence of H bonding or Cu(I) coordination on the filled thiolate orbital energy, or on the effect of metal-metal interaction on the Au(I) acceptor orbital energy. Crystal data for Au(Spy)(PPh2py) (1): triclinic, space group P1 (No. 2), with a = 8.3975(4) A, b = 11.0237(5) A, c = 12.4105(6) A, alpha = 98.6740(10) degrees, beta = 105.3540(10) degrees, gamma = 110.9620(10) degrees, V = 995.33(8) A3, Z = 2, R1 = 3.66% (I > 2 sigma(I)), wR2 = 9.04% (I > 2 sigma(I)) for 2617 unique reflections. Crystal data for [(Au(SpyH)(PPh2py))2](PF6)2 (2): triclinic, space group P1 (No. 2), with a = 14.0284(3) A, b = 14.1093(3) A, c = 15.7027(2) A, alpha = 97.1870(10) degrees, beta = 96.5310(10) degrees, gamma = 117.1420(10) degrees, V = 2692.21(9) A3, Z = 2, R1 = 7.72% (I > 2 sigma(I)), wR2 = 15.34% (I > 2 sigma(I)) for 5596 unique reflections. Crystal data for [(AuCu(mu-Spy)(mu-PPh2py))2](PF6)2 (3): monoclinic, space group P2(1)/c (No. 14), with a = 19.6388(6) A, b = 16.3788(4) A, c = 17.2294(5) A, beta = 91.48 degrees, V = 5540.2(3) A3, Z = 4, R1 = 3.99% (I > 2 sigma(I)), wR2 = 8.38% (I > 2 sigma(I)) for 10,597 unique reflections.

Platinum diimine bis(acetylide) complexes: synthesis, characterization, and luminescence properties

A new set of luminescent platinum(II) diimine complexes has been synthesized and characterized. The anionic ligands in these complexes are arylacetylides. The complexes are brightly emissive in fluid solution with relative emission quantum yields phiem ranging from 3 x 10(-3) to 10(-1). Two series of complexes have been investigated. The first has the formula Pt(Rphen)(C...CC6H5)2 where Rphen is 1,10-phenanthroline substituted in the 5-position with R = H, Me, Cl, Br, NO2, or C...CC6H5, while the second has the formula Pt(dbbpy)(C=CC6H4X)2 where dbbpy = 4,4'-di(tert-butyl)bipyridine and X = H, Me, F, or NO2. From NMR, IR, and electronic spectroscopies, all of the complexes are assigned a square planar coordination geometry with cis-alkynyl ligands. The crystal structure of Pt(phen)(Ce-CC6H4CH3)2 confirms this assignment. All of the complexes exhibit an absorption band at ca. 400 nm that corresponds to a Pt d-->pi*diimine charge-transfer transition. The variation of lambdamax for this band with substituent variation supports this assignment. From similar changes in the energy of the solution luminescence as a function of substituents R and X, the emissive excited state is also of MLCT origin, but with spin-forbidden character on the basis of excited-state lifetime measurements (0.01-5.6 micros). The complexes undergo electron-transfer quenching, showing good Stern-Volmer behavior using 10-methylphenothiazine and N,N,N',N'-tetramethylbenzidine as reductive quenchers. Excited-state reduction potentials are estimated on the basis of a simple thermochemical analysis. Crystal data for Pt(phen)(C...CC6H4CH3)2: monoclinic, space group C2/c, a = 19.0961(1) A, b = 10.4498(1) A, c = 11.8124(2) A, beta = 108.413(1) degrees, V = 2236.49 A3, number of reflections 1614, number of variables 150, R1 = 0.0163, wR2 (I > 2sigma) = 0.0410.

Exploring biomolecular recognition using optical biosensors

Understanding the basic forces that determine molecular recognition helps to elucidate mechanisms of biological processes and facilitates discovery of innovative biotechnological methods and materials for therapeutics, diagnostics, and separation science. The ability to measure interaction properties of biological macromolecules quantitatively across a wide range of affinity, size, and purity is a growing need of studies aimed at characterizing biomolecular interactions and the structural elements that drive them. Optical biosensors have provided an increasingly impactful technology for such biomolecular interaction analyses. These biosensors record the binding and dissociation of macromolecules in real time by transducing the accumulation of mass of an analyte molecule at the sensor surface coated with ligand molecule into an optical signal. Interactions of analytes and ligands can be analyzed at a microscale and without the need to label either interactant. Sensors enable the detection of bimolecular interaction as well as multimolecular assembly. Most notably, the method is quantitative and kinetic, enabling determination of both steady-state and dynamic parameters of interaction. This article describes the basic methodology of optical biosensors and presents several examples of its use to investigate such biomolecular systems as cytokine growth factor-receptor recognition, coagulation factor assembly, and virus-cell docking.

Mechanisms of systemic autoimmunity in murine models of SLE

Our laboratory has utilized spontaneous and experimentally induced models of systemic autoimmunity in mice in order to elucidate the cellular deficiencies in immunoregulation that are essential to this process. In the spontaneously autoimmune mouse strains, genetic defects in T and B cell tolerance are the primary abnormalities that drive the syndrome. The induced chronic graft-vs-host model depends on abnormal T-B interactions resulting from allogeneic recognition of major histocompatibility complex (MHC) class II. Future investigations will target the biochemistry of the loss of tolerance and the specificity of autoreactive T cells that provide help for autoantibody production.

The outcome of vestibular nerve section for intractable vertigo: the patient's point of view

To document the outcome of vestibular nerve section from the patient's point of view we reviewed 102 patients who had undergone vestibular nerve section 1 to 10 years after operation. Only 3 patients had experienced further vertigo attacks: 2 of these were cured by a further, this time translabyrinthine vestibular nerve section; 1 patient developed multiple sclerosis. In contrast, about 50% of patients developed some subjective problem with balance while standing or walking; in 15% it was present all the time and of moderate severity. Despite this, over 85% of patients reported that they felt much better or back to normal after the operation and were satisfied with the outcome. The development and application of objective preoperative measures of vestibular and, in particular, vestibulospinal function might improve patient selection for vestibular nerve section and thus reduce the number of dissatisfied patients.

Repairing the degenerative mitral valve: ten- to fifteen-year follow-up

From January 1969 to December 1992, mitral valve reconstructive operations were performed on 155 patients with degenerative mitral valve disease. There were 102 male and 53 female patients, with a mean age of 60.5 +/- 9.2 years, a mean duration of symptoms of 3.8 +/- 2.7 years, and 34% were in atrial fibrillation. All patients were in New York Heart Association functional classes III and IV before operation. The degree of mitral regurgitation was severe in 94% and moderate in 6%, and 50.9% of patients had moderate to severe impairment of left ventricular function. Emergency operation was undertaken in 7.1% of cases; 19% of patients underwent additional procedures. All patients had posterior mitral leaflet pathology and 19 patients had anterior mitral leaflet pathology. Ring annuloplasty was used in only 3% of cases. The operative mortality rate was 3.9%, 9% of patients had morbid events, and 4.5% of patients had repair failure within 6 months. All patients have been followed up with serial echocardiography for a mean time of 5.2 +/- 0.3 years (range 0.5 to 24 years). Immediately after operation, 92.9% had no mitral regurgitation to mild mitral regurgitation. At last follow-up, 96.9% had no mitral regurgitation to mild mitral regurgitation by echocardiography and 98% of patients were in New York Heart Association functional classes I and II. The actuarial survival at 15 years was 46% +/- 11%, freedom from reoperation was 84.9% +/- 11%, freedom from infective endocarditis was 96.0% +/- 11%, freedom from thromboembolism was 90.4% +/- 11%, and freedom from all valve-related events was 36.7% +/- 11%. It is well documented that repair of degenerative mitral valves offers excellent short-term and medium long-term benefits. This series represents the longest follow-up reported outside Europe. Our results beyond 10 years support our conclusion that an annuloplasty ring is not an absolute prerequisite for achieving successful repair of proven durability in most patients with degenerative mitral valve disease.

The discoverer of x-rays: Wilhelm Conrad Roentgen

"Immortal is his work. Immortal his name." This dedication to Wilhelm Roentgen, the discoverer of x-rays, is much deserved. As a meticulous scientist, Roentgen devised and repaired all the apparatus needed for his experiments, and he did most of the work himself.

Sodium in gramicidin: an example of a permion

The reaction path and free energy profile of Na+ were computed in the interior of the channel protein gramicidin, with the program MOIL. Gramicidin was represented in atomic detail, but surrounding water and lipid molecules were not included. Thus, only short range interactions were investigated. The permeation path of the ion was an irregular spiral, far from a straight line. Permeation cannot be described by motions of a single Na+ ion. The minimal energy path includes significant motion of water and channel atoms as well as motion of the permeating ion. We think of permeation as motion of a permion, a quasi-particle that includes the many body character of the permeation process, comparable with quasi-particles like holes, phonons, and electrons of solid-state physics. Na+ is accompanied by a plug of water molecules, and motions of water, Na+, and the atoms of gramicidin are highly correlated. The permion moves like a linear polymer made of waters and ion linked and moving coherently along a zigzag line, following the reptation mechanism of polymer transport. The effective mass, free energy, and memory kernel (of the integral describing time-dependent friction) of short range interactions were calculated. The effective mass of the permion (properly normalized) is much less than Na+. Friction varies substantially along the path. The free energy profile has two deep minima and several maxima. In certain regions, the dominant motions along the reaction path are those of the channel protein, not the permeating ion: there, ion waits while the other atoms move. At these waiting sites, the permion's motion along the reaction path is a displacement of the atoms of gramicidin that prepare the way for the Na+ ion.

Accuracy of interpretation of cranial computed tomography scans in an emergency medicine residency program

STUDY OBJECTIVES

To determine the concordance of emergency physicians and radiologists in interpreting cranial computed tomography (CT) scans. The study also sought to determine the clinical significance of misinterpretations of cranial CT scans by emergency physicians.

DESIGN

Prospective cohort study.

SETTING

A county hospital emergency medicine residency program.

PARTICIPANTS

Five hundred fifty-five patients undergoing CT scanning during emergency department evaluation.

RESULTS

Forty-nine percent (272) of the indications for CT scanning were for trauma, 14.2% (79) were for cerebrovascular accident, 25.1% (139) were for headache, 15.1% (84) were for seizure, and 13.7% (76) were for miscellaneous reasons. The radiologists interpreted 46.1% (256) of the CT scans as abnormal. The most frequent abnormalities were scalp hematoma, 15.2% (39); infarction, 14.1% (36); calcification, 6.3% (16); contusion, 6.3% (16); parenchymal hemorrhage, 5.1% (13); and mass, 5.1% (13). Nonconcordance between radiologists and emergency physicians was found in 38.7% (206) of the cases. Potentially clinically significant misinterpretations were found in 24.1% (131) of the total sample. These misinterpretations included 62 missed major findings (11.4% of total sample): 25 new infarcts, 10 mass lesions, 8 cases of cerebral edema, 8 parenchymal hemorrhages, 5 contusions, 4 subarachnoid hemorrhages, 1 epidural hematoma, and 1 subdural hematoma. However, on chart review, only three patients (0.6%) were found to have been managed inappropriately, and none had an adverse outcome.

CONCLUSION

The misinterpretation rate of cranial CT scans by emergency physicians is of potential clinical concern. However, clinical mismanagement is rare. We recommend that more formal education in CT interpretation be included in residency training and continuing medical education programs for emergency physicians.

Developmental changes in achievement evaluation: motivational implications of self-other differences

In order to explore the development of self-evaluative biases, children at 3 age levels (5-6, 7-8, 9-10) evaluated themselves or another child when given social or temporal comparison feedback. Evaluative biases were indicated by higher evaluations for the self than another, especially after failure. Children at different ages were not differentially responsive to temporal vs. social comparison information. However, evaluative bias in response to the type of evaluation differed by age; there was greater bias for general ability evaluations by older children and greater bias for specific performance evaluations by younger children. Alternative explanations for these self-other differences were minimized, as differences in visual orientation were held constant and differences in knowledge of effort were controlled statistically. Other aspects of the design as well as sex differences support a motivational interpretation of these biases. How these biases are manifested is related to children's level of understanding and concerns at different ages.

Genetic structure of a natural population of Dictyostelium discoideum, a cellular slime mould

Dictyostelium discoideum is a eukaryotic microbe feeding on soil bacteria. A first step towards describing the genetic structure of populations of this species was made by examining multiple isolates from a single locale. The isolates were grown clonally and their RFLP patterns compared, using a probe specific for a family of tRNA genes. Thirty-nine types were distinguished in 54 isolates. To determine if genetic exchange occurs among members of the population, an analysis of linkage disequilibrium was performed on the RFLP data. Little disequilibrium was found, implying gene flow in the population. In conflict with this result is the finding that no recombinant progeny were recovered from many attempted crosses between pairs of isolates. The tentative conclusion is that genetic exchange does not in fact occur, and that the observed shuffling of RFLP bands is caused by insertion and excision of transposons known to be associated with the tRNA genes of Dictyostelium.

Charges, currents, and potentials in ionic channels of one conformation

Flux through an open ionic channel is analyzed with Poisson-Nernst-Planck (PNP) theory. The channel protein is described as an unchanging but nonuniform distribution of permanent charge, the charge distribution observed (in principle) in x-ray diffraction. Appropriate boundary conditions are derived and presented in some generality. Three kinds of charge are present: (a) permanent charge on the atoms of the protein, the charge independent of the electric field; (b) free or mobile charge, carried by ions in the pore as they flux through the channel; and (c) induced (sometimes called polarization) charge, in the pore and protein, created by the electric field, zero when the electric field is zero. The permanent charge produces an offset in potential, a built-in Donnan potential at both ends of the channel pore. The system is completely solved for bathing solutions of two ions. Graphs describe the distribution of potential, concentration, free (i.e., mobile) and induced charge, and the potential energy associated with the concentration of charge, as well as the unidirectional flux as a function of concentration of ions in the bath, for a distribution of permanent charge that is uniform. The model shows surprising complexity, exhibiting some (but not all) of the properties usually attributed to single filing and exchange diffusion. The complexity arises because the arrangement of free and induced charge, and thus of potential and potential energy, varies, sometimes substantially, as conditions change, even though the channel structure and conformation (of permanent charge) is strictly constant. Energy barriers and wells, and the concomitant binding sites and binding phenomena, are outputs of the PNP theory: they are computed, not assumed. They vary in size and location as experimental conditions change, while the conformation of permanent charge remains constant, thus giving the model much of its interesting behavior.

MRL mice produce anti-Su autoantibody, a specificity associated with systemic lupus erythematosus

Certain autoimmune mouse strains exhibit features similar to human SLE. To discover genetic and immunologic events governing expression of a new SLE-associated antibody, the presence of anti-Su and its relationship to other SLE-related antibodies (anti-Sm, -ribonucleoprotein, -Ro (SS-A), -La (SS-B)) were determined in MRL and other autoimmune and nonautoimmune mice. By double immunodiffusion, sera from 34/183 (19%) 4- to 10-mo-old MRL/Mp-lpr/lpr (MRL/lpr) and 28/108 (26%) 8- to 20-mo-old MRL/Mp(-)+/+ (MRL/+) mice were positive for anti-Su antibodies. Anti-Sm antibodies were found in 60/183 (33%) and 39/108 (36%) of these animals, respectively. The two specificities were found together in individual mice more frequently than would be predicted by chance. In contrast, C57BL/6-lpr/lpr (B6/lpr) mice rarely showed either specificity. Analysis of F1 hybrids between B6/lpr and MRL/lpr and of F1 x MRL/lpr backcross mice suggested that a small number of autosomal recessive genes controlled the anti-Su and anti-Sm responses. With the exception of a single NZB serum sample, NZB, BXSB, and nonautoimmune mice were negative for all antibodies tested, and no mice were positive for anti-RNP, anti-Ro, or anti-La. MRL/lpr and MRL/+ autoimmune mice thus provide unique models for human SLE, because they express several of the SLE-specific marker autoantibodies. These models should be useful in disclosing molecular and immunologic events governing autoantibody expression in this condition.

MRL mice produce anti-Su autoantibody, a specificity associated with systemic lupus erythematosus

Certain autoimmune mouse strains exhibit features similar to human SLE. To discover genetic and immunologic events governing expression of a new SLE-associated antibody, the presence of anti-Su and its relationship to other SLE-related antibodies (anti-Sm, -ribonucleoprotein, -Ro (SS-A), -La (SS-B)) were determined in MRL and other autoimmune and nonautoimmune mice. By double immunodiffusion, sera from 34/183 (19%) 4- to 10-mo-old MRL/Mp-lpr/lpr (MRL/lpr) and 28/108 (26%) 8- to 20-mo-old MRL/Mp(-)+/+ (MRL/+) mice were positive for anti-Su antibodies. Anti-Sm antibodies were found in 60/183 (33%) and 39/108 (36%) of these animals, respectively. The two specificities were found together in individual mice more frequently than would be predicted by chance. In contrast, C57BL/6-lpr/lpr (B6/lpr) mice rarely showed either specificity. Analysis of F1 hybrids between B6/lpr and MRL/lpr and of F1 x MRL/lpr backcross mice suggested that a small number of autosomal recessive genes controlled the anti-Su and anti-Sm responses. With the exception of a single NZB serum sample, NZB, BXSB, and nonautoimmune mice were negative for all antibodies tested, and no mice were positive for anti-RNP, anti-Ro, or anti-La. MRL/lpr and MRL/+ autoimmune mice thus provide unique models for human SLE, because they express several of the SLE-specific marker autoantibodies. These models should be useful in disclosing molecular and immunologic events governing autoantibody expression in this condition.

Pacemaker implantation in children: a 21-year experience

Forty-one children, 20 boys and 21 girls, aged 11 days to 19 years (mean 9.9 years) at initial pacemaker implant, were followed 1 to 248 months (mean 90 months). Ten (mean age 8.2 years) were implanted between 1966 and 1972 (Group I), 14 (mean age 9.9 years) between 1973 and 1980 (Group II) and 17 (mean age 10.9 years) from 1981 through April 1988 (Group III). Arrhythmias were congenital complete heart block in 19, postoperative heart block in 15, acquired heart block in 3, sick sinus syndrome in 3, and bradycardia-induced ventricular fibrillation in 1. Twenty-eight of 41 children had a transvenous implant: 40% of Group I, 71% of Group II and 82% of Group III. Thirteen were cephalic, four subclavian and 11 jugular. Generator site was pectoral in 19, abdominal in 12, intrathoracic in one, and retromammary in nine of 12 girls aged 10 years or more at implant. In Groups I, II and III, 5, 14 and 6 had VOO or VVI units; 5, 0 and 8 dual chamber (VAT, VDD and DDD) pacemakers; 0, 0 and 1 AAI; and 0, 0 and 2 rate-modulated (VVIR) units at initial implant. The average interval between pacer-related hospitalizations in Groups I, II and III was 20, 42, and 39 months. Complications included infection in six, hemothorax in one, and impending pacemaker erosion in one. Six patients died, one of pacer infection, four from primary cardiac disease, and one suddenly without apparent reason. Follow-up continues in 31: 14 are employed full-time, three are homemakers, eight are full-time students, and six are active pre-schoolers.(ABSTRACT TRUNCATED AT 250 WORDS)

Validating the certification process for infection control practice

Approximately 5 years ago a task analysis was conducted by the Certification Board of Infection Control (CBIC) to describe infection control practice. This task analysis served as the basis for development of the certification examination. This article describes the process used to update and revalidate the original task analysis to ensure the continued validity and job relatedness of the certification process. Using a modified Delphi technique, several panels of representative expert infection control practitioners (ICPs), a total of 29 persons, participated in an iterative process to define the practice dimensions of infection control and to link these practice dimensions to the certification examination. In general, there was a high level of congruence between respondents on the original task analysis and the expert panels, although a few differences in practice were identified among ICPs in extended care facilities and a few new tasks were identified. In addition, a revised content outline for the examination was created by placing clusters of knowledge statements together around common themes.

Primary pulmonary amyloidosis. An unusual case with 14 years' survival

A 70-year-old woman had nodular lesions and a right hilar infiltrate visible on chest x-ray film. The diagnosis of pulmonary amyloidosis was established by a transbronchial lung biopsy. Over the next 14 years, the patient remained relatively asymptomatic but developed extensive pulmonary involvement. The case illustrates the long and relatively benign course of primary pulmonary amyloidosis.

Sustained arrhythmias in hypertrophic obstructive cardiomyopathy

Patients with hypertrophic obstructive cardiomyopathy are subject to syncope and sudden death. Ambulatory monitoring discloses frequent and complex ventricular ectopy in many of these patients, and the occurrence of ventricular tachycardia suggests an increased risk of sudden death. We prospectively evaluated whether induced sustained arrhythmia could explain episodes of cerebral dysfunction in hypertrophic cardiomyopathy. Seven consecutive symptomatic patients (six of whom had an intraventricular gradient of 40 to 130 mm Hg) were subjected to atrial and ventricular stimulation. An electrophysiologic abnormality that would explain the symptoms was identified in every patient: supraventricular tachycardia was present in two, sustained ventricular tachycardia in three, ventricular fibrillation in one, and a prolonged QT interval and dispersion of ventricular refractoriness in one. Antiarrhythmic drugs were selected on the basis of the response to electrophysiologic testing. There has been no recurrence of symptoms in 120 patient-months of follow-up. This experience suggests that arrhythmias are the principal cause of syncope or sudden death in obstructive cardiomyopathy and that electrophysiologic study may be useful in selecting prophylactic therapy.

Direct demonstration that the abundant 6-kilobase herpes simplex virus type 1 mRNA mapping between 0.23 and 0.27 map units encodes the major capsid protein VP5

The two partially colinear 6-kilobase (kb) and 1.5-kb mRNAs mapping between 0.23 and 0.27 map units on the herpes simplex virus type 1 genome were precisely located. The 5' end of the 6-kb mRNA was located 28 bases downstream of the sequence ATATATT and was 10 bases to the left of the BamHI site at 0.268. This position is ca. 90 bases to the left of our earlier reported sequence (R. J. Frink, K. G. Draper, and E. K. Wagner, Proc. Natl. Acad. Sci. U.S.A. 78:6139-6143, 1981). We used a polyclonal antibody made against purified herpes simplex virus type 1 VP5 to demonstrate that the 155,000-dalton translation product of the 6-kb mRNA is this capsid protein. The antibody did not react with the 35,000-dalton translation product of the 1.5-kb mRNA. We also confirmed our identification of VP5 as the translation product of the 6-kb mRNA by comparison of tryptic peptides of the in vitro-translated protein and authentic VP5.

High-resolution characterization of herpes simplex virus type 1 transcripts encoding alkaline exonuclease and a 50,000-dalton protein tentatively identified as a capsid protein

Four partially overlapping mRNAs (1.9, 2.3, 3.9, and 4.5 kilobases [kb]) were located between 0.16 and 0.19 map units on the herpes simplex virus type 1 genome. Their direction of transcription was found to be from right to left. The 2.3-kb mRNA was found to be early (beta), whereas the others were late (beta gamma). Partial sequence analysis of the DNA encoding these genes indicated that the promoter for the 2.3-kb mRNA shares structural features with other early (beta) promoters. In vitro translation of hybrid-selected mRNA indicated that among the proteins these mRNAs encode are an 82,000-dalton (d) polypeptide reactive with a monoclonal antibody against herpes simplex virus type 2 alkaline exonuclease and a 50,000-d polypeptide weakly reactive with a polyclonal antibody made against the capsid protein VP19C. Further experiments suggested that the 2.3-kb mRNA encodes the 82,000-d polypeptide, whereas one (or both) of the larger mRNAs encodes the 50,000-d protein. A novel finding was that the 1.9-kb mRNA appears to share part of the translational reading frame for alkaline exonuclease, but any polypeptide it encodes does not react with the monoclonal antibody to this enzyme.

Glycopeptides of the type-common glycoprotein gD of herpes simplex virus types 1 and 2

We have carried out detailed structural studies of the glycopeptides of glycoprotein gD of herpes simplex virus types 1 and 2. We first examined and compared the number of N-asparagine-linked oligosaccharides present in each glycoprotein. We found that treatment of either pgD-1 or pgD-2 with endo-beta-N-acetylglucosaminidase H (Endo H) generated three polypeptides which migrated more rapidly than pgD on gradient sodium dodecyl sulfate-polyacrylamide gels. Two of the faster-migrating polypeptides were labeled with [(3)H]mannose, suggesting that both pgD-1 and pgD-2 contained three N-asparagine-linked oligosaccharides. Second, we characterized the [(3)H]mannose-labeled tryptic peptides of pgD-1 and pgD-2. We found that both glycoproteins contained three tryptic glycopeptides, termed glycopeptides 1, 2, and 3. Gel filtration studies indicated that the molecular weights of these three peptides were approximately 10,000, 3,900, and 1,800, respectively, for both pgD-1 and pgD-2. Three methods were employed to determine the size of the attached oligosaccharides. First, the [(3)H]mannose-labeled glycopeptides were treated with Endo H, and the released oligosaccharide was chromatographed on Bio-Gel P6. The size of this molecule was estimated to be approximately 1,200 daltons. Second, Endo H treatment of [(35)S]methionine-labeled glycopeptide 2 reduced the molecular size of this peptide from approximately 3,900 to approximately 2,400 daltons. Third, glycopeptide 2 isolated from the gD-like molecule formed in the presence of tunicamycin was approximately 2,200 daltons. From these experiments, the size of each N-asparagine-linked oligosaccharide was estimated to be approximately 1,400 to 1,600 daltons. Our experiments indicated that glycopeptides 2 and 3 each contained one N-asparagine-linked oligosaccharide chain. Although glycopeptide 1 was large enough to accommodate more than one oligosaccharide chain, the experiments with Endo H treatment of the glycoprotein indicated that there were only three N-asparagine-linked oligosaccharides present in pgD-1 and pgD-2. Further studies of the tryptic glycopeptides by reverse-phase high-performance liquid chromatography indicated that all of the glycopeptides were hydrophobic in nature. In the case of glycopeptide 2, we observed that when the carbohydrate was not present, the hydrophobicity of the peptide increased. The properties of the tryptic glycopeptides of pgD-1 were compared with the properties predicted from the deduced amino acid sequence of gD-1. The size and amino acid composition compared favorably for glycopeptides 1 and 2. Glycopeptide 3 appeared to be somewhat smaller than would be predicted from the deduced sequence of gD-1. It appears that all three potential glycosylation sites predicted by the amino acid sequence are utilized in gD-1 and that a similar number of glycosylation sites are present in gD-2.

Detailed analysis of the portion of the herpes simplex virus type 1 genome encoding glycoprotein C

We previously showed that the right third of HindIII fragment L (0.59 to 0.65) of herpes simplex virus type 1 (HSV-1) encodes a family of mRNAs some members of which appear to be related by splicing. In the experiments described in this communication, we determined the nucleotide sequence of the DNA encoding this mRNA family and precisely located the mRNAs associated with this DNA sequence. The major mRNA species is unspliced and encoded by a 2.520-nucleotide region. Just upstream of the 5' end are TATA and CAT box sequences characteristic of HSV-1 promoters. The 3' end maps near a region containing a nominal polyadenylation signal. Three minor species (2,400, 2,200, and 1,900 bases, respectively) appear to share a very short leader sequence with the 5' end of the major mRNA and are then encoded by uninterrupted DNA sequences beginning about 100, 400, and 625 bases downstream of the 5' end of the major unspliced mRNA. These positions map at or very near positions which agree reasonably well with consensus splice acceptor sequences. The fourth mRNA is encoded by a contiguous 730-nucleotide sequence at the 3' end of the major unspliced mRNA and has its 5' end just downstream of recognizable TATA and CAT box sequences. We suggest that this mRNA is controlled by its own promoter. The nucleotide sequence data, in combination with the mRNA localization, demonstrate four potential polypeptides encoded by the region. The largest is 1,569 bases long and defines a 523-amino acid protein with sequence features characteristic of a glycoprotein. This was confirmed to be HSV-1 glycoprotein C by immune precipitation of the in vitro translation product of the major unspliced mRNA, performed with a polyspecific antibody to HSV-1 envelope glycoproteins (anti-env-1 serum), and by comparison of tryptic peptides of this translation product with those of authentic HSV-1 glycoprotein C. Polypeptides encoded by some of the minor species also were tentatively identified.

Measurement of bacterial cell wall in tissues by solid-phase radioimmunoassay: correlation of distribution and persistence with experimental arthritis in rats

We have developed sensitive and specific solid-phase radioimmunoassays to quantitate the distribution and persistence of bacterial antigen in rats developing arthritis in response to a single injection of streptococcal cell wall material. Three separate assays were specific for either the A polysaccharide (N-acetyl-D-glucosamine), A-variant polysaccharide (polyrhamnose), or peptidoglycan (D-ala-D-ala) moieties of the streptococcal cell wall. Antigen was detected in all tissues surveyed, although the greatest amount was in the liver and spleen. By using three fractions of cell wall separated by size, we have shown that the development of arthritis correlates with the degree of cell wall deposited and persisting in the joints. Further statistical analyses suggested differences in metabolism by different tissues and differential metabolism of different antigenic epitopes in some cases.