C60-Fullerene monomalonate adducts selectively inactivate neuronal nitric oxide synthase by uncoupling the formation of reactive oxygen intermediates from nitric oxide production

C(60)-Fullerene monomalonate adducts inactivate selectively the neuronal nitric oxide synthase isoform in a manner completely preventable by the concurrent presence of superoxide dismutase and catalase. This inactivation is time-, fullerene concentration-, and turnover-dependent and is not reversible by dilution. The di(carboxypropan-3-ol)methano-[60]-fullerene (diol adduct) has no effect on NADPH consumption by nNOS as measured in the absence of arginine substrate, but dramatically increases NADPH consumption in the presence of arginine. This fullerene-enhanced NADPH consumption is linked to oxygen as electron acceptor and is accompanied by the increased production of hydrogen peroxide. These effects of fullerene monomalonate adducts are unique to the nNOS isoform and are not observed using either the iNOS or the eNOS isoform. The inhibitory effects of fullerene monomalonate adducts are unaltered and insurmountable by increased concentrations of arginine, tetrahydrobiopterin, or calmodulin. These observations indicate that fullerene monomalonate adducts uncouple in the presence of arginine the formation of reactive oxygen intermediates from NO production by nNOS. These reactive oxygen intermediates dissociate from the enzyme and, acting from solution, inactivate NOS NO forming activity.

Testing for concordant equilibria between population samples

A substantial body of theory has been developed to assess the effect of evolutionary forces on the distribution of genotypes, both single and multilocus, within populations. One area where the potential for application of this theory has not been fully appreciated concerns the extent to which population samples differ. Within populations, the divergence of genotype or haplotype frequencies from that expected under Hardy-Weinberg (HW) or linkage equilibrium can be measured as disequilibria coefficients. To assess population samples for concordant equilibria, an analytical framework for comparing disequilibria coefficients between populations is necessary. Here we present log-linear models to evaluate such hypotheses. These models have broad utility ranging from conventional population genetics to genetic epidemiology. We demonstrate the use of these log-linear models (1) as a test for genetic association with disease and (2) as a test for different levels of linkage disequilibria between human populations.

Influence of H2S and thiols on the binding of alkenes and alkynes to ReS4-: the spectator sulfido effect

The three-component reaction of ReS4- (1), H2S, and unsaturated substrates (un = alkene, alkyne) affords the ReV derivatives Re(S)(S2un)(SH)2-. These adducts arise via the addition of H2S to intermediate dithiolates ReS2(S2C2R4)- and dithiolenes ReS2(S2C2R2)-. The species [ReS[S2C2(tms)2](SH)2]-, [ReS(S2C7H10)(SH)2]- (3), and [ReS(S2C2H4)(SH)2]- are prepared according to this route. Similarly, the selenolate-thiolate complex [ReS(S2C7H10)(SeH)(SH)]- (5) is produced by the reaction of [ReS2(S2C7H10)]- with H2Se. The corresponding reactions using benzenethiol in place of H2S afford the more thermally robust adducts [ReS[S2C2(tms)2](SH)(SPh)]-, [ReS(S2C7H10)(SH)(SPh)]- (7), and [ReS(S2C2H4)(SH)(SPh)]-. Norbornanedithiolato compounds 3, 5, and 7 are obtained as pairs of isomers that differ in terms of the relative orientation of the norbornane bridgehead relative to the Re=S unit. The reaction of [ReS(S2C7H10)(SD)2]- (3-d2) with H2S to give 3 is proposed to proceed via elimination of D2S and subsequent addition of H2S. Variable-temperature 1H NMR measurements on the equilibrium of [ReS(S2C6H12)(SPh)(SH)]- with 1,1-hexene, and PhSH gave the following results: deltaH = -7 (+/- 1) kJ x mol(-1); deltaS = 23 (+/- 4) J x mol(-1) x K(-1). Solutions of ethanedithiol and 1 react with C2(tms)2 and C2H4 to give [ReS[S2C2(tms)2](S2C2H4)]- and [ReS(S2C2H4)2]-, respectively, concomitant with loss of H2S. The pathway for the ethanedithiol reaction is examined using 2-mercaptoethanol, affording [ReS[S2C2(tms)2](SC2H4OH)]-, which does not cyclize. Treatment of a solution of diphenylbutadiyne and 1 with PhSH gives two isomers of the dithiolene [ReS(SH)(SPh)[S2C2Ph(C2Ph)]]-. The corresponding reaction of ethanedithiol, diphenylbutadiyne, and 1 affords the 1,4-diphenylbutadiene-1,2,3,4-tetrathiolate complex [[ReS(S2C2H4)]2(S4C4Ph2)]2-.

X-ray crystal structure of an anti-Buckminsterfullerene antibody fab fragment: biomolecular recognition of C(60)

We have prepared a monoclonal Buckminsterfullerene specific antibody and report the sequences of its light and heavy chains. We also show, by x-ray crystallographic analysis of the Fab fragment and by model building, that the fullerene binding site is formed by the interface of the antibody light and heavy chains. Shape-complementary clustering of hydrophobic amino acids, several of which participate in putative stacking interactions with fullerene, form the binding site. Moreover, an induced fit mechanism appears to participate in the fullerene binding process. Affinity of the antibody-fullerene complex is 22 nM as measured by competitive binding. These findings should be applicable not only to the use of antibodies to assay and direct potential fullerene-based drug design but could also lead to new methodologies for the production of fullerene derivatives and nanotubes as well.

Ethical decision making and patient autonomy: a comparison of physicians and patients in Japan and the United States

BACKGROUND

Patient-centered decision making, which in the United States is typically considered to be appropriate, may not be universally endorsed, thereby harboring the potential to complicate the care of patients from other cultural backgrounds in potentially unrecognized ways. This study compares the attitudes toward ethical decision making and autonomy issues among academic and community physicians and patients of medical center outpatient clinics in Japan and the United States.

METHODS

A questionnaire requesting judgments about seven clinical vignettes was distributed (in English or Japanese) to sample groups of Japanese physicians (n = 400) and patients (n = 65) as well as US physicians (n = 120) and patients (n = 60) that were selected randomly from academic institutions and community settings in Japan (Tokyo and the surrounding area) and the United States (the Stanford/Palo Alto, CA, area). Responses were obtained from 273 Japanese physicians (68%), 58 Japanese patients (89%), 98 US physicians (82%), and 55 US patients (92%). Physician and patient sample groups were compared on individual items, and composite scores were derived from subsets of items relevant to patient autonomy, family authority, and physician authority.

RESULTS

A majority of both US physicians and patients, but only a minority of Japanese physicians and patients, agreed that a patient should be informed of an incurable cancer diagnosis before their family is informed and that a terminally ill patient wishing to die immediately should not be ventilated, even if both the doctor and the patient's family want the patient ventilated (Japanese physicians and patients vs US physicians and patients, p < 0.001). A majority of respondents in both Japanese sample groups, but only a minority in both US sample groups, agreed that a patient's family should be informed of an incurable cancer diagnosis before the patient is informed and that the family of an HIV-positive patient should be informed of this disease status despite the patient's opposition to such disclosure (Japanese physicians and patients vs US physicians and patients, p < 0.001). Physicians in both Japan and the United States were less likely than patients in their respective countries to agree with physician assistance in the suicide of a terminally ill patient (Japanese physicians and patients vs US physicians and patients, p < 0.05). Across various clinical scenarios, all four respondent groups accorded greatest authority to the patient, less to the family, and still less to the physician when the views of these persons conflicted. Japanese physicians and patients, however, relied more on family and physician authority and placed less emphasis on patient autonomy than the US physicians and patients sampled. Younger respondents placed less emphasis on family and physician authority.

CONCLUSIONS

Family and physician opinions are accorded a larger role in clinical decision making by the Japanese physicians and patients sampled than by those in the United States, although both cultures place a greater emphasis on patient preferences than on the preferences of the family or physician. Our results are consistent with the view that cultural context shapes the relationship of the patient, the physician, and the patient's family in medical decision making. The results emphasize the need for clinicians to be aware of these issues that may affect patient and family responses in different clinical situations, potentially affecting patient satisfaction and compliance with therapy.

Trauma ultrasound feasibility during helicopter transport

OBJECTIVE

To evaluate the feasibility of performing a standard four-view focused abdominal sonography for trauma (FAST) examination during helicopter transport using a hand-carried ultrasound machine.

METHODS

In this prospective observational study, actual and simulated trauma patients were evaluated using the SonoSite 180 ultrasound machine by two air transport programs serving Level I trauma centers. FAST examinations were performed in flight by emergency medicine faculty, residents, flight nurses, and ultrasound technologists, who rated the difficulty posed by various factors using Likert scales (0 = not difficult to 5 = impossible). BK 117, Bell 230, and BO 105 medical helicopters flew in all aviating modes. Pilots were queried regarding avionics variations throughout the flights.

RESULTS

Ten flight sonographers performed 21 FAST examinations on 14 patients (five actual, nine simulated). The median Likert value for each parameter was 0 except for patient position, which was 1 (somewhat difficult). Interquartile ranges were 0-0 for vibration, bedding, IV catheters, monitor cables, and ventilator; 0-0.5 for backboard straps; and 0-1 for sunlight, patient position, spider straps, gurney straps, and clothing. Mean examination duration, was 3.0 minutes (range 1.5 to 5.5 minutes, SD 1.3). Pilots reported no effects on avionics in any flight mode.

CONCLUSION

The FAST examination using the SonoSite 180 in flight was rated by 10 evaluators to be performed easily. Examinations were conducted quickly and did not interfere with helicopter avionics. This digital ultrasound machine is the first one small enough to be used in most medical helicopters.

Evaluating linkage and linkage disequilibrium: use of excess sharing and transmission disequilibrium methods in affected sib pairs

Two popular and robust approaches to analysing affected sib pair (ASP) data for linkage are the traditional excess sharing methods and the transmission/disequilibrium test (TDT). Here we derive an overall test of linkage for multi-allelic ASP marker data which comprises two component tests: one for excess sharing and one for transmission disequilibrium. This method has several advantages. Firstly the overall test of linkage is often more powerful than either of the two component tests. Secondly the method makes it possible to determine the contribution of linkage disequilibrium (LD), in addition to linkage, to an overall positive linkage result. This is useful because the presence of LD in addition to linkage may suggest that the marker locus is in very close proximity to a disease susceptibility gene. Thirdly the method provides estimates of the risk associated with transmission of the different marker alleles.

Alkaloid-fullerene systems through photocycloaddition reactions

The photocycloaddition of tertiary amines to ¿60fullerene (C(60)) is an interesting and useful reaction. We wished to extend the applications of this type of reaction through an investigation of the photoaddition of alkaloids to C(60) for the purpose of synthesizing novel and complex photoadducts that are difficult to obtain by usual methods. Irradiation of tazettine (2) or gramine (3) with C(60) in toluene leads to formation of one monoadduct (6 or 7), whereas scandine (1a) or 10-hydroxyscandine (1b) reacts with C(60) photochemically to give two products, the expected ¿6,6 monoadduct (5a, 5b) and a new type of monoadduct with a bis-¿6, 6 closed structure (4a, 4b). These new structures were characterized by UV-vis, FT-IR, (1)H NMR, (13)C NMR, (1)H-(1)H COSY, ROESY, HMQC (heteronuclear multiple-quantum coherence), and HMBC (heteronuclear multiple-bond connectivity) spectroscopy. The techniques of time-of-flight secondary ion MS (TOF-SIMS) and field desorption MS (FD-MS) were used for the mass determination. (3)He NMR analysis of the product mixture from photoaddition of 1a to C(60) containing a (3)He atom ((3)He@C(60)) led to two peaks at -9.091 and -11.090 ppm relative to gaseous (3)He, consistent with formation of a ¿6, 6-closed monoadduct and a bis-¿6,6 closed adduct. Presumably, the bis-¿6, 6 closed adducts are formed by an intramolecular ¿2 + 2 cycloaddition of the vinyl group to the adjacent 6,6-ring junction of C(60) after the initial photocycloaddition.

Inhibition of nitric oxide synthase isoforms by tris-malonyl-C(60)-fullerene adducts

C(3)-tris-malonyl-C(60)-fullerene and D(3)-tris-malonyl-C(60)-fullerene derivatives inhibit citrulline and NO formation by all three nitric oxide synthase isoforms in a manner fully reversible by dilution. The inhibition of citrulline formation by C(3)-tris-malonyl-C(60)-fullerene occurs with IC(50) values of 24, 17, and 123 microM for the neuronal, endothelial, and inducible nitric oxide synthase (NOS) isoforms, respectively. As measured at 100 microM l-arginine, neuronal NOS-catalyzed nitric oxide formation was inhibited 50% at a concentration of 25 microM C(3)-tris-malonyl-C(60)-fullerene. This inhibition was a multisite, positively cooperative inhibition with a Hill coefficient of 2.0. C(3)-tris-malonyl-C(60)-fullerene inhibited the arginine-independent NADPH-oxidase activity of nNOS with an IC(50) value of 22 microM but had no effects on its cytochrome c reductase activity at concentrations as high as 300 microM. The inhibition of nNOS activity by C(3)-tris-malonyl-C(60)-fullerene reduced the maximal velocity of product formation but did not alter the EC(50) value for activation by calmodulin. C(3)-tris-malonyl-C(60)-fullerene reduced the maximal velocity of citrulline formation by inducible NOS without altering the K(m) for l-arginine substrate or the EC(50) value for tetrahydrobiopterin cofactor. As measured by sucrose density gradient centrifugation, fully inhibitory concentrations of C(3)-tris-malonyl-C(60)-fullerene did not produce a dissociation of nNOS dimers into monomers. These observations are consistent with the proposal that C(3)-tris-malonyl-C(60)-fullerene inhibits the inter-subunit transfer of electrons, presumably by a reversible distortion of the dimer interface.

How important is DNA replication for mutagenesis?

Rates of mutation and substitution in mammals are generally greater in the germ lines of males. This is usually explained as resulting from the larger number of germ cell divisions during spermatogenesis compared with oogenesis, with the assumption made that mutations occur primarily during DNA replication. However, the rate of cell division is not the only difference between male and female germ lines, and mechanisms are known that can give rise to mutations independently of DNA replication. We investigate the possibility that there are other causes of male-biased mutation. First, we show that patterns of variation at approximately 5,200 short tandem repeat (STR) loci indicate a higher mutation rate in males. We estimate a ratio of male-to-female mutation rates of approximately 1.9. This is significantly greater than 1 and supports a greater rate of mutation in males, affecting the evolution of these loci. Second, we show that there are chromosome-specific patterns of nucleotide and dinucleotide composition in mammals that have been shaped by mutation at CpG dinucleotides. Comparable patterns occur in birds. In mammals, male germ lines are more methylated than female germ lines, and these patterns indicate that differential methylation has played a role in male-biased vertebrate evolution. However, estimates of male mutation bias obtained from both classes of mutation are substantially lower than estimates of cell division bias from anatomical data. This discrepancy, along with published data indicating slipped-strand mispairing arising at STR loci in nonreplicating DNA, suggests that a substantial percentage of mutation may occur in nonreplicating DNA.

Appendicitis at the millennium

Acute appendicitis is a common clinical problem. Accurate and prompt diagnosis is essential to minimize morbidity. While the clinical diagnosis may be straightforward in patients who present with classic signs and symptoms, atypical presentations may result in diagnostic confusion and delay in treatment. Helical computed tomography (CT) and graded compression color Doppler ultrasonography (US) are highly accurate means of establishing the diagnosis. These imaging modalities have now assumed critical roles in the treatment of patients suspected to have appendicitis. The purpose of this article is threefold: to provide an update on new information regarding the pathophysiology, clinical diagnosis, and laparoscopic treatment of acute appendicitis; to describe the state-of-the art use of CT and US in diagnosing this disease entity; and to address the role of medical imaging in this patient population.

Harmonic hepatic US with microbubble contrast agent: initial experience showing improved characterization of hemangioma, hepatocellular carcinoma, and metastasis

PURPOSE

To characterize blood flow in focal hepatic lesions with harmonic ultrasonographic (US) imaging and a microbubble contrast agent.

MATERIALS AND METHODS

Thirty patients with known hepatic masses were examined after injection of a perfluorocarbon microbubble agent. Tumor vascularity was assessed with continuous, harmonic gray-scale imaging with a low mechanical index (MI). Tumor vascular volume was assessed with brief, high-MI insonation called interval-delay imaging, which caused microbubble destruction. As the total contrast agent volume in the liver reflects the total vascular volume, quantitation of lesion enhancement relative to normal hepatic enhancement helped determine the vascular volume of the tumor relative to that of normal parenchyma.

RESULTS

Low-MI continuous harmonic imaging showed lesional vessels in hepatocellular carcinomas, minimal or no vessels in hemangiomas, and variable vascularization in metastases. High-MI interval-delay imaging showed greater enhancement in hepatocellular carcinomas than in normal liver (P <.02) and showed less enhancement in hemangiomas than in normal liver (P <.02). Enhancement in metastases was greater in the margins than in the center; as a result, the lesions appeared smaller (P <.03) and less well defined on the interval-delay images.

CONCLUSION

Contrast-enhanced harmonic imaging appears superior to conventional Doppler US for hepatic mass characterization. Low-MI continuous and high-MI interval-delay imaging can help assess tumor vascular pattern and microvascular volume.

Pulse inversion imaging of liver blood flow: improved method for characterizing focal masses with microbubble contrast

RATIONALE AND OBJECTIVES

To create a microbubble contrast image of vessels that lie below the resolution of an ultrasound system, a technique is required that detects preferentially the agent echo, rejecting that from tissue. Harmonic imaging exploits the nonlinear behavior of microbubbles but forces a compromise between image sensitivity and axial resolution. The authors describe and evaluate a new method that overcomes this compromise and improves contrast imaging performance: pulse inversion imaging.

METHODS

Sequences of pulses of alternate phase are transmitted into tissue and their echoes summed. A prototype scanner equipped with pulse inversion was used to image phantoms and 16 patients with focal liver masses.

RESULTS

Pulse inversion images show contrast sensitivity and resolution superior to that of harmonic images. Vessels can be imaged at an incident power sufficiently low to avoid destroying the agent, allowing unique visualization of tumor vasculature. Distinct patterns were seen in hemangiomas, metastases, and hepatocellular carcinomas.

CONCLUSIONS

Pulse inversion imaging is an improved bubble-specific imaging method that extends the potential of contrast ultrasonography.

Precision trace gas analysis by FT-IR spectroscopy. 1. Simultaneous analysis of CO2, CH4, N2O, and CO in air

We report the development of a method of trace gas analysis based on 1-cm-1 resolution Fourier transform infrared (FT-IR) spectroscopy, deployable in both laboratory and field applications. Carbon dioxide, methane, nitrous oxide, and carbon monoxide may be analyzed simultaneously in a single air sample using this method. We have demonstrated that the method can provide analytical precision of the order of +/- 0.15 mumol mol-1 for CO2, +/- 0.9 nmol mol-1 for CH4, +/- 0.3 nmol mol-1 for N2O, and +/- 0.3 nmol mol-1 for CO, expressed as mole fractions in dry air. The analytical precision is in all cases competitive with or superior to that of the more usual methods of analysis for these trace gases, namely, nondispersive infrared spectroscopy for CO2 and gas chromatography-based techniques for CH4, N2O, and CO. The novel FT-IR method relies on calibration using synthetically calculated absorbance spectra and a chemometric multivariate calibration algorithm, classical least squares.

Precision trace gas analysis by FT-IR spectroscopy. 2. The 13C/12C isotope ratio of CO2

We report the development of a method of carbon stable isotope ratio analysis based on 1-cm-1 resolution Fourier transform infrared (FT-IR) spectroscopy, deployable in both laboratory and field applications. We demonstrate the determination of the 13C/12C ratio of CO2 (i.e., delta 13CO2) in air with an analytical precision of the order of +/- 0.1/1000 (i.e., +/- 0.01%). The FT-IR method relies on calibration using synthetically calculated absorbance spectra and a multivariate calibration algorithm. The method requires no sample preparation other than optional drying of the sample and may be applied directly to ambient air samples containing approximately 350 mumol mol-1 CO2 (molar mixing ratio). It may also be applied to samples more concentrated in CO2, such as human breath, approximately 5% CO2. We demonstrate the utility of the technique to the analysis of delta 13CO2 in air during an experimental field campaign and to the laboratory-based analysis of human breath. A similar method could also be used to determine the H/D ratio in atmospheric water vapor.

Modeling linkage and association with evaluation of common sampling schemes

The probability model of parental transmission (of a multiallelic marker) to affected offspring has been reparameterized in such a way as to distinguish the recombination fraction parameter from the association parameters. The advantage of this reparameterization is that statistical tests can be developed which disentangle linkage and association. It is shown that these tests perform well compared with a standard approach that is commonly used. Further, the simulated data (Problem 2) enable a comparison to be made of the performance of these tests under different family sampling schemes.

Nongynecologic applications of transvaginal US

Transvaginal ultrasonography (US) is a noninvasive, readily available imaging technique that has greatly enhanced diagnostic sensitivity and accuracy for both gynecologic and nongynecologic disease. High-frequency US probes placed in the vagina allow high-resolution assessment of all the pelvic viscera, including portions of the gut and urinary tract. In addition, they allow visualization of the peritoneum of the pelvic pouch and the pelvic side walls without interference from bowel gas or adipose tissue. Evaluation of these areas requires a modified US technique that includes the use of the highest-frequency probes with angulation of the transducer to allow assessment of the region of interest. In women of childbearing age, the similarity of symptoms in gynecologic and gastrointestinal tract disease in particular underscores the potential utility of transvaginal US, which may, for example, help differentiate appendicitis in a pelvic appendix from pelvic inflammatory disease. Transvaginal US may also help determine the correct course of therapy, thereby improving patient management. Other indications for transvaginal US include assessment for pelvic appendicitis and diverticulitis, rectal and perianal complications of Crohn disease, and ureteric and bladder calculi and tumors as well as evaluation of the anal sphincters in women with fecal incontinence. Transvaginal US is also superior to routine US in the detection and characterization of ascites and peritoneal disease. Transvaginal US examination should include the entire pelvic cavity and contents, especially in women at risk for pelvic sepsis or peritoneal disease.

Role of US in the detection, characterization, and staging of cholangiocarcinoma

Cholangiocarcinoma is a rare tumor with a broad range of pathologic and clinical manifestations that demonstrates a myriad of imaging findings. Recent experience indicates that a more definitive role is possible for ultrasonography (US) in the evaluation of cholangiocarcinoma. Dilatation of the intrahepatic bile ducts is the most frequently seen US abnormality in patients with ductal cholangiocarcinoma. Klatskin tumors classically manifest as segmental dilatation and nonunion of the right and left ducts at the porta hepatis. Papillary and nodular ductal cholangiocarcinoma are relatively easy to see at US: Papillary tumors resemble polypoid intraluminal masses, whereas nodular cholangiocarcinoma manifests as a discrete smooth mass with associated mural thickening. Infiltrating ductal cholangiocarcinoma at the porta hepatis is the most common subtype but is the most difficult to appreciate at US. Peripheral cholangiocarcinoma may be either nodular or infiltrating at US: The nodular form predominates and appears as a solitary mass with a distinct right lobe predilection, whereas the infiltrative form is rare and manifests as a diffusely abnormal liver echotexture. In capable hands, modern high-resolution US equipment with color Doppler imaging capability is highly sensitive in the detection, characterization, and determination of the potential for resectability of cholangiocarcinoma. Thus, use of US may obviate more invasive procedures in some patients and help identify those patients for whom further investigation would be contributory.

Synthesis and Photophysical Properties of Steroid-Linked Porphyrin−Fullerene Hybrids

[structure: see text] The photophysical properties of porphyrin-linked fullerene hybrids have generated significant interest, and a number of these hybrids synthesized by this group and others have been extensively characterized with respect to energy and charge-transfer processes that take place upon photoexcitation. Present studies of steroid-linked dyads demonstrate the extent to which through-bond effects operate in these systems.

In vivo polysaccharide-specific IgG isotype responses to intact Streptococcus pneumoniae are T cell dependent and require CD40- and B7-ligand interactions

In vivo Ig responses to soluble, haptenated polysaccharide (PS) Ags are T cell independent and do not require CD40 ligand (CD40L). However, little is known regarding the regulation of in vivo PS-specific Ig responses to intact bacteria. We immunized mice with a nonencapsulated, type 2 Streptococcus pneumoniae (R36A) and compared the parameters that regulated in vivo Ig isotype responses to the bacterial cell wall C-PS determinant, phosphorylcholine (PC), relative to Ig responses to the cell wall protein, pneumococcal surface protein A. Consistent with previous reports using soluble PS and protein Ags, the anti-PC and anti-pneumococcal surface protein A responses differed in that the anti-PC response was induced more rapidly, had a distinctive Ig isotype profile, and failed to demonstrate boosting upon secondary challenge with R36A. However, in contrast to previous studies, the IgG anti-PC response was TCR-alphabeta+ T cell dependent, required CD40L, and was blocked by administration of CTLA4 Ig. The nature of the T cell help for the anti-PC response had distinct features in that it was only partially blocked by CTLA4 Ig and was dependent upon both CD4+ and CD8+ T cells. Surprisingly, whereas the IgM anti-PC response was largely T cell independent, a strong requirement for CD40L was still observed, suggesting the possibility of an in vivo T cell-independent source for CD40L-dependent help. These data suggest that the regulatory parameters that govern in vivo Ig responses to purified, soluble PS Ags may not adequately account for PS-specific Ig responses to intact bacteria.

Testing for HIV: current practices in the academic ED

The objective of this study was to determine common practices for testing for Human Immunodeficiency Virus (HIV), particularly in patients with other sexually transmitted diseases (STD) in emergency departments (ED) with residency training in Emergency Medicine. Via mail, 112 directors of academic emergency medicine programs in the United States were surveyed. Surveys from 95 academic institutions were completed, returned, and included in the analysis. Three EDs (3%) routinely tested for HIV in patients with suspected STD. HIV testing was performed in the ED in 54% of responding institutions under special circumstances such as employee testing after occupational exposures (54%), cases of rape (46%), and suspicion of HIV infection by clinical manifestations other than suspected STD (36%). Based on the results it was determined that academic EDs do not routinely test for HIV in patients suspected of having a STD and have variable testing practices and policies regarding other possible HIV exposures.

Transvaginal sonography of the anal sphincter: reliable, or not?

OBJECTIVE

The purpose of this study was to validate the use of transvaginal sonography for anal sphincter evaluation, compare this technique with the more commonly used transanal technique, and explain a publication that suggested that transvaginal sonography is unreliable.

SUBJECTS AND METHODS

The study population consisted of 50 women, of whom 44 prospectively underwent transanal and transvaginal sonography. The six remaining patients with surgical confirmation underwent only transvaginal sonography. All images were interpreted by the examining radiologist and then reviewed by a second radiologist who was unaware of the first radiologist's interpretations. Defects in the external and internal anal sphincters, the status of the perineal body, and any perianal collections or fistulas were documented.

RESULTS

Twenty-five of the 50 patients showed sphincteric defects. Twenty-two had a defect in the external anal sphincter, of whom 16 had a matching internal anal sphincter defect. Four patients had an isolated internal anal sphincter defect. Surgery in nine of these 22 patients confirmed the defects seen on sonography. The 10th patient who underwent surgery had scar tissue rather than a tear in the external anal sphincter that corresponded with the defect seen on sonography. Defects were identified in all patients presenting with fecal incontinence who had undergone either a primary repair or an anterior sphincteroplasty. Of the 25 patients with intact sphincters on both transvaginal and transanal sonography, four had other significant findings including two perianal abscesses and two T3 rectal carcinomas. In 40 of the 44 patients who were prospectively imaged using both techniques, the sonographic findings were in agreement. Review, performed by a second radiologist who was unaware of the first radiologist's interpretations, verified the findings resulting in an 88.6% interobserver agreement. In all patients, perineal body assessment and assessment of perianal inflammatory disease was more accurate with the transvaginal technique.

CONCLUSION

Transvaginal sonography is a reliable method for evaluating the anal sphincter, with an accuracy equivalent to that of the transanal technique. Transvaginal sonography is preferable for evaluation of the perineal body and perianal inflammatory processes.

Crystallographic evidence for the electronic distribution in (2,4-cyclopentadien-1-yl-idenehydrazono)triphenylphosphorane

The title compound, C23H19N2P, can be graphically represented by several canonical forms. Its crystal structure analysis shows a clear bond alternation in the cyclopentadiene ring, which continues in the azo substructure, indicating that the resonance form containing the nonaromatic neutral cyclopentadienylidene moiety describes the actual hybrid form better than other 'inner ionic' resonance forms containing the aromatic anionic cyclopentadienylic portion. The preference for an s-transoid (E) geometry for the P1-N1-N2-C1 substructure was also confirmed over the other possible s-cisoid (Z) conformer.

Gas at abdominal US: appearance, relevance, and analysis of artifacts

PURPOSE

To describe the spectrum of ultrasonographic (US) appearances of intraluminal gas, including two clinically relevant gas artifacts.

MATERIALS AND METHODS

Observations were made in patients and reproduced in an animal model, an ex vivo gut preparation, and a tissue-mimicking phantom. Appearances were classified according to a physical model of the interaction between sound and collections of gas.

RESULTS

Free bubbles of gas appeared as bright echogenic foci extending artifactually owing to lateral and axial blooming. This causes bubbles that abut the gut wall to enhance the layer one echo, which corresponds to the interface between the mucosa and the luminal contents. Such bubbles can also falsely appear to be within the gut wall itself owing to elevation averaging and thereby cause the artifact pseudo-pneumatosis intestinalis. Isolated groups of small bubbles created a characteristic periodicity and tapering of the distal echo pattern. In the extreme case, in which many such echoes are superimposed, "dirty shadowing" occurs. A contiguous pocket of gas may cause the gut wall to appear artifactually thickened (i.e., pseudo-thickened gut). This was shown to be a form of mirror image artifact.

CONCLUSION

Classification of the effects of gas on US images according to their physical characteristics may aid in their interpretation. Appreciating two previously undescribed artifacts, pseudo-pneumatosis intestinalis and pseudo-thickened gut, will improve the usefulness of abdominal US.