Bifidobacterium infantis associates with T cell immunity in human infants and is sufficient to enhance antigen-specific T cells in mice

Bacille Calmette-Guerin (BCG) vaccine can elicit good TH1 responses in neonates. We hypothesized that the pioneer gut microbiota affects vaccine T cell responses. Infants who are HIV exposed but uninfected (iHEU) display an altered immunity to vaccination. BCG-specific immune responses were analyzed at 7 weeks of age in iHEU, and responses were categorized as high or low. Bifidobacterium longum subsp. infantis was enriched in the stools of high responders, while Bacteroides thetaiotaomicron was enriched in low responders at time of BCG vaccination. Neonatal germ-free or SPF mice orally gavaged with live B. infantis exhibited significantly higher BCG-specific T cells compared with pups gavaged with B. thetaiotaomicron. B. infantis and B. thetaiotaomicron differentially affected stool metabolome and colonic transcriptome. Human colonic epithelial cells stimulated with B. infantis induced a unique gene expression profile versus B. thetaiotaomicron. We thus identified a causal role of B. infantis in early-life antigen-specific immunity.

Bacterial microbiome and host inflammatory gene expression in foreskin tissue

The penile epithelial microbiome remains underexplored. We sequenced human RNA and a segment of the bacterial 16S rRNA gene from the foreskin tissue of 144 adolescents from South Africa and Uganda collected during penile circumcision after receipt of 1-2 doses of placebo, emtricitabine + tenofovir disoproxil fumarate, or emtricitabine + tenofovir alafenamide to investigate the microbiome of foreskin tissue and its potential changes with antiretroviral use. We identified a large number of anaerobic species, including Corynebacterium acnes, which was detected more frequently in participants from South Africa than Uganda. Bacterial populations did not differ by treatment received, and no differentially abundant taxa were identified between placebo versus active drug recipients. The relative abundance of specific bacterial taxa was negatively correlated with expression of genes downstream of the innate immune response to bacteria and regulation of inflammation. Our results show no difference in the tissue microbiome of the foreskin with short-course antiretroviral use but that bacterial taxa were largely inversely correlated with inflammatory gene expression, consistent with commensal colonization.

Copper intrauterine device increases vaginal concentrations of inflammatory anaerobes and depletes lactobacilli compared to hormonal options in a randomized trial

Effective contraceptives are a global health imperative for reproductive-aged women. However, there remains a lack of rigorous data regarding the effects of contraceptive options on vaginal bacteria and inflammation. Among 218 women enrolled into a substudy of the ECHO Trial (NCT02550067), we evaluate the effect of injectable intramuscular depot medroxyprogesterone acetate (DMPA-IM), levonorgestrel implant (LNG), and a copper intrauterine device (Cu-IUD) on the vaginal environment after one and six consecutive months of use, using 16S rRNA gene sequencing and multiplex cytokine assays. Primary endpoints include incident BV occurrence, bacterial diversity, and bacterial and cytokine concentrations. Secondary endpoints are bacterial and cytokine concentrations associated with later HIV seroconversion. Participants randomized to Cu-IUD exhibit elevated bacterial diversity, increased cytokine concentrations, and decreased relative abundance of lactobacilli after one and six months of use, relative to enrollment and other contraceptive options. Total bacterial loads of women using Cu-IUD increase 5.5 fold after six months, predominantly driven by increases in the concentrations of several inflammatory anaerobes. Furthermore, growth of L. crispatus (MV-1A-US) is inhibited by Cu2+ ions below biologically relevant concentrations, in vitro. Our work illustrates deleterious effects on the vaginal environment induced by Cu-IUD initiation, which may adversely impact sexual and reproductive health.

Therapeutic efficacy against Mycobacterium tuberculosis using ID93 and liposomal adjuvant formulations

Mycobacterium tuberculosis (M.tb) has led to approximately 1.3 million deaths globally in 2020 according to the World Health Organization (WHO). More effective treatments are therefore required to prevent the transmission of M.tb. Although Bacille Calmette-Guérin (BCG), a prophylactic vaccine against M.tb, already exists, other vaccines are being developed that could help boost BCG's noted incomplete protection. This includes ID93 + GLA-SE, an adjuvanted protein vaccine which is being tested in Phase 2 clinical trials. The aim of this study was to test new lipid-based adjuvant formulations with ID93 in the context of a therapeutic vaccine, which we hypothesize would act as an adjunct to drug treatment and provide better outcomes, such as survival, than drug treatment alone. The recent success of another adjuvanted recombinant protein vaccine, M72 + AS01_E (GlaxoSmithKline Biologicals), which after 3 years provided approximately 50% efficacy against TB pulmonary disease, is paving the way for new and potentially more effective vaccines. We show that based on selected criteria, including survival, T helper 1 cytokine responses, and resident memory T cells in the lung, that a liposomal formulation of GLA with QS-21 (GLA-LSQ) combined with ID93 provided enhanced protection over drug treatment alone.

Initiating Intramuscular Depot Medroxyprogesterone Acetate Increases Frequencies of Th17-like Human Immunodeficiency Virus Target Cells in the Genital Tract of Women in South Africa: A Randomized Trial

BACKGROUND

Cervicovaginal CD4+ T cells are preferential targets for human immunodeficiency virus (HIV) infection and have consequently been used as a proxy measure for HIV susceptibility. The ECHO randomized trial offered a unique opportunity to consider the association between contraceptives and Th17-like cells within a trial designed to evaluate HIV risk. In a mucosal substudy of the ECHO trial, we compared the impact of initiating intramuscular depot medroxyprogesterone acetate (DMPA-IM), copper-IUD, and the levonorgestrel (LNG) implant on cervical T cells.

METHODS

Cervical cytobrushes from 58 women enrolled in the ECHO trial were collected at baseline and 1 month after contraceptive initiation. We phenotyped cervical T cells using multiparameter flow cytometry, characterized the vaginal microbiome using 16s sequencing, and determined proteomic signatures associated with Th17-like cells using mass spectrometry.

RESULTS

Unlike the LNG implant or copper-IUD, DMPA-IM was associated with higher frequencies of cervical Th17-like cells within 1 month of initiation (P = .012), including a highly susceptible, activated population co-expressing CD38, CCR5, and α4β7 (P = .003). After 1 month, women using DMPA-IM also had more Th17-like cells than women using the Cu-IUD (P = .0002) or LNG implant (P = .04). Importantly, in women using DMPA-IM, proteomic signatures signifying enhanced mucosal barrier function were associated with the increased abundance of Th17-like cells. We also found that a non-Lactobacillus-dominant microbiome at baseline was associated with more Th17-like cells post-DMPA-IM (P = .03), although this did not influence barrier function.

CONCLUSIONS

Our data suggest that DMPA-IM-driven accumulation of HIV-susceptible Th17-like cells might be counteracted by their role in maintaining mucosal barrier integrity.

CLINICAL TRIALS REGISTRATION

NCT02550067.

Comparison of Female Genital Tract Cytokine and Microbiota Signatures Induced by Initiation of Intramuscular DMPA and NET-EN Hormonal Contraceptives - a Prospective Cohort Analysis

Background

Cervicovaginal inflammation, bacterial microbiota and hormonal contraceptives all influence sexual and reproductive health. To date, the effects of intramuscular depo-medroxyprogesterone acetate (DMPA-IM) versus injectable norethisterone enanthate (NET-EN) on vaginal microbiota or cytokines have not been compared back-to-back, although in-vitro data suggest that DMPA-IM and NET-EN have different pharmacokinetic and biologic activities. This study aimed at comparing the effects of DMPA-IM versus NET-EN initiation on cervicovaginal cytokines and microbiota in women at high risk for sexually transmitted infections (STIs) assigned to the respective contraceptives.

Methods

We collected socio-demographic characteristics and vaginal samples from women initiating DMPA-IM (ECHO Trial; n = 53) and NET-EN (UChoose Trial; n = 44) at baseline and after two consecutive injections to assess cytokine concentrations by Luminex, vaginal microbiota by 16S rRNA gene sequencing, STIs, bacterial vaginosis (BV) and candidiasis.

Results

Cytokine concentrations did not change significantly after initiating DMPA-IM or NET-EN, although NET-EN versus DMPA-IM-associated profiles were distinct. While the abundance of bacterial taxa associated with optimal and non-optimal microbiota fluctuated with DMPA-IM use, overall community composition did not significantly change with either contraceptive. HSV-2 serology, chlamydial infection, gonorrhoea and candidiasis did not influence the associations between contraceptive type and cervicovaginal cytokines or microbiota.

Conclusions

Both DMPA-IM and NET-EN use did not lead to broad inflammatory or microbiota changes in the female genital tract of sub-Saharan African women. This suggests that NET-EN is likely a viable option for contraception in African women at high risk of BV and STIs.

Qualification of ELISA and neutralization methodologies to measure SARS-CoV-2 humoral immunity using human clinical samples

In response to the SARS-CoV-2 pandemic many vaccines have been developed and evaluated in human clinical trials. The humoral immune response magnitude, composition and efficacy of neutralizing SARS-CoV-2 are essential endpoints for these trials. Robust assays that are reproducibly precise, linear, and specific for SARS-CoV-2 antigens would be beneficial for the vaccine pipeline. In this work we describe the methodologies and clinical qualification of three SARS-CoV-2 endpoint assays. We developed and qualified Endpoint titer ELISAs for total IgG, IgG1, IgG3, IgG4, IgM and IgA to evaluate the magnitude of specific responses to the trimeric spike (S) antigen and total IgG specific to the spike receptor binding domain (RBD) of SARS-CoV-2. We also qualified a pseudovirus neutralization assay which evaluates functional antibody titers capable of inhibiting the entry and replication of a lentivirus containing the Spike antigen of SARS-CoV-2. To complete the suite of assays we qualified a plaque reduction neutralization test (PRNT) methodology using the 2019-nCoV/USA-WA1/2020 isolate of SARS-CoV-2 to assess neutralizing titers of antibodies in plasma from normal healthy donors and convalescent COVID-19 individuals.

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Precision, Linearity, and Specificity are essential for Clinical Assay Qualification.

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Vaccine or Infection-induced humoral response magnitude can be evaluated by high-throughput ELISAs.

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Neutralization of SARS-CoV-2 is the gold-standard for in vitro vaccine efficacy evaluations.

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ELISA, pseudovirus neutralization and PRNT assays are Clinically Qualified for SARS-CoV-2 vaccine trials.

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Positive WHO control sample of 250 ABU equals 4.7 EPT for total IgG against SARS-CoV-2 trimeric spike antigen in ELISAs.

Qualification of ELISA and neutralization methodologies to measure SARS-CoV-2 humoral immunity using human clinical samples

In response to the SARS-CoV-2 pandemic many vaccines have been developed and evaluated in human clinical trials. The humoral immune response magnitude, composition and efficacy of neutralizing SARS-CoV-2 are essential endpoints for these trials. Robust assays that are reproducibly precise, linear, and specific for SARS-CoV-2 antigens would be beneficial for the vaccine pipeline. In this work we describe the methodologies and clinical qualification of three SARS-CoV-2 endpoint assays. We developed and qualified Endpoint titer ELISAs for total IgG, IgG1, IgG3, IgG4, IgM and IgA to evaluate the magnitude of specific responses to the trimeric spike (S) antigen and total IgG specific to the spike receptor binding domain (RBD) of SARS-CoV-2. We also qualified a pseudovirus neutralization assay which evaluates functional antibody titers capable of inhibiting the entry and replication of a lentivirus containing the Spike antigen of SARS-CoV-2. To complete the suite of assays we qualified a plaque reduction neutralization test (PRNT) methodology using the 2019-nCoV/USA-WA1/2020 isolate of SARS-CoV-2 to assess neutralizing titers of antibodies in plasma from normal healthy donors and convalescent COVID-19 individuals.

Preconception helminth infection alters offspring microbiota and immune subsets in a mouse model

Both maternal microbiota and helminth infection may alter offspring immunity but the relationship between these is underexplored. We hypothesized that maternal helminth exposure prior to pregnancy has lasting consequences on offspring intestinal microbiota and consequent immunity. Female BALB/c adult mice were infected with 500L3 Nippostrongylus brasiliensis (N brasiliensis). Infection was cleared by ivermectin treatment, and mice were mated 3 weeks post-infection (NbM). Control mice were not infected but were exposed to ivermectin (NvM). We analysed maternal gut microbiota during pregnancy, breastmilk microbiota and offspring faecal microbiota and immunity 2 weeks after delivery. During pregnancy, NbM (Mothers previously infected with Nippostrongylus brasiliensis) displayed significantly altered stool bacterial communities (R2  = .242; P = .001), with increased abundance of Enterococcaceae versus NvM (Naive mothers). Similarly, we observed a profound impact on breastmilk microbiota in NbM vs NvM. Moreover, NbM pups showed significantly altered gut microbial communities at 14 days of age versus those born to NvM with increased relative abundance of Coriobacteriaceae and Micrococcaceae. These changes were associated with alterations in pup immunity including increased frequencies and numbers of activated CD4 T cells (CD4 + CD44hi) in NbM offspring spleens. Taken together, we show that preconception helminth infections impact offspring immunity possibly through alteration of maternal and offspring microbiota.

Feeding-Related Gut Microbial Composition Associates With Peripheral T-Cell Activation and Mucosal Gene Expression in African Infants

Background

Exclusive breastfeeding reduces the rate of postnatal human immunodeficiency virus (HIV) transmission compared to nonexclusive breastfeeding; however, the mechanisms of this protection are unknown. Our study aimed to interrogate the mechanisms underlying the protective effect of exclusive breastfeeding.

Methods

We performed a prospective, longitudinal study of infants from a high-HIV-prevalence, low-income setting in South Africa. We evaluated the role of any non-breast milk feeds, excluding prescribed medicines on stool microbial communities via 16S rRNA gene sequencing, peripheral T-cell activation via flow cytometry, and buccal mucosal gene expression via quantitative polymerase chain reaction assay.

Results

A total of 155 infants were recruited at birth with mean gestational age of 38.9 weeks and mean birth weight of 3.2 kg. All infants were exclusively breastfed (EBF) at birth, but only 43.5% and 20% remained EBF at 6 or 14 weeks of age, respectively. We observed lower stool microbial diversity and distinct microbial composition in exclusively breastfed infants. These microbial communities, and the relative abundance of key taxa, were correlated with peripheral CD4+ T-cell activation, which was lower in EBF infants. In the oral mucosa, gene expression of chemokine and chemokine receptors involved in recruitment of HIV target cells to tissues, as well as epithelial cytoskeletal proteins, was lower in EBF infants.

Conclusions

These data suggest that nonexclusive breastfeeding alters the gut microbiota, increasing T-cell activation and, potentially, mucosal recruitment of HIV target cells. Study findings highlight a biologically plausible mechanistic explanation for the reduced postnatal HIV transmission observed in EBF infants.

Compositional analyses reveal correlations between taxon-level gut bacterial abundance and peripheral T cell marker expression in African infants

Although exclusive breastfeeding has been linked to lower rates of postnatal HIV transmission compared to nonexclusive breastfeeding, mechanisms underlying this are unclear. Across a longitudinally sampled cohort of South African infants, we showed that exclusively breastfed (EBF) infants had altered gut bacterial communities when compared to nonexclusively breastfed (NEBF) infants, as well as reduced peripheral CD4 + T cell activation and lowered chemokine and chemokine receptor expression in the oral mucosa. We further demonstrated that the relative abundance of key taxa was correlated with peripheral CD4 + T cell activation. Here, we supplement those findings by using compositional data analyses to identify shifts in the abundance of several Bifidobacteria strains relative to select strains of Escherichia, Bacteroides, and others that are associated with the transition to NEBF. We illustrate that the abundance ratio of these taxa is tightly correlated with feeding modality and is a strong predictor of peripheral T cell activation. More broadly, we discuss our study in the context of novel developments and explore future directions for the field.

Genomic erosion and extensive horizontal gene transfer in gut-associated Acetobacteraceae

BACKGROUND

Symbiotic relationships between animals and bacteria have profound impacts on the evolutionary trajectories of each partner. Animals and gut bacteria engage in a variety of relationships, occasionally persisting over evolutionary timescales. Ants are a diverse group of animals that engage in many types of associations with taxonomically distinct groups of bacterial associates. Here, we bring into culture and characterize two closely-related strains of gut associated Acetobacteraceae (AAB) of the red carpenter ant, Camponotus chromaiodes.

RESULTS

Genome sequencing, assembly, and annotation of both strains delineate stark patterns of genomic erosion and sequence divergence in gut associated AAB. We found widespread horizontal gene transfer (HGT) in these bacterial associates and report elevated gene acquisition associated with energy production and conversion, amino acid and coenzyme transport and metabolism, defense mechanisms, and lysine export. Both strains have acquired the complete NADH-quinone oxidoreductase complex, plausibly from an Enterobacteriaceae origin, likely facilitating energy production under diverse conditions. Conservation of several lysine biosynthetic and salvage pathways and accumulation of lysine export genes via HGT implicate L-lysine supplementation by both strains as a potential functional benefit for the host. These trends are contrasted by genome-wide erosion of several amino acid biosynthetic pathways and pathways in central metabolism. We perform phylogenomic analyses on both strains as well as several free living and host associated AAB. Based on their monophyly and deep divergence from other AAB, these C. chromaiodes gut associates may represent a novel genus. Together, our results demonstrate how extensive horizontal transfer between gut associates along with genome-wide deletions leads to mosaic metabolic pathways. More broadly, these patterns demonstrate that HGT and genomic erosion shape metabolic capabilities of persistent gut associates and influence their genomic evolution.

CONCLUSIONS

Using comparative genomics, our study reveals substantial changes in genomic content in persistent associates of the insect gastrointestinal tract and provides evidence for the evolutionary pressures inherent to this environment. We describe patterns of genomic erosion and horizontal acquisition that result in mosaic metabolic pathways. Accordingly, the phylogenetic position of both strains of these associates form a divergent, monophyletic clade sister to gut associates of honey bees and more distantly to Gluconobacter.

Meta-analysis of effects of exclusive breastfeeding on infant gut microbiota across populations

Previous studies on the differences in gut microbiota between exclusively breastfed (EBF) and non-EBF infants have provided highly variable results. Here we perform a meta-analysis of seven microbiome studies (1825 stool samples from 684 infants) to compare the gut microbiota of non-EBF and EBF infants across populations. In the first 6 months of life, gut bacterial diversity, microbiota age, relative abundances of Bacteroidetes and Firmicutes, and predicted microbial pathways related to carbohydrate metabolism are consistently higher in non-EBF than in EBF infants, whereas relative abundances of pathways related to lipid metabolism, vitamin metabolism, and detoxification are lower. Variation in predicted microbial pathways associated with non-EBF infants is larger among infants born by Caesarian section than among those vaginally delivered. Longer duration of exclusive breastfeeding is associated with reduced diarrhea-related gut microbiota dysbiosis. Furthermore, differences in gut microbiota between EBF and non-EBF infants persist after 6 months of age. Our findings elucidate some mechanisms of short and long-term benefits of exclusive breastfeeding across different populations.

Disruption of maternal gut microbiota during gestation alters offspring microbiota and immunity

BACKGROUND

Early life microbiota is an important determinant of immune and metabolic development and may have lasting consequences. The maternal gut microbiota during pregnancy or breastfeeding is important for defining infant gut microbiota. We hypothesized that maternal gut microbiota during pregnancy and breastfeeding is a critical determinant of infant immunity. To test this, pregnant BALB/c dams were fed vancomycin for 5 days prior to delivery (gestation; Mg), 14 days postpartum during nursing (Mn), or during gestation and nursing (Mgn), or no vancomycin (Mc). We analyzed adaptive immunity and gut microbiota in dams and pups at various times after delivery.

RESULTS

In addition to direct alterations to maternal gut microbial composition, pup gut microbiota displayed lower α-diversity and distinct community clusters according to timing of maternal vancomycin. Vancomycin was undetectable in maternal and offspring sera, therefore the observed changes in the microbiota of stomach contents (as a proxy for breastmilk) and pup gut signify an indirect mechanism through which maternal intestinal microbiota influences extra-intestinal and neonatal commensal colonization. These effects on microbiota influenced both maternal and offspring immunity. Maternal immunity was altered, as demonstrated by significantly higher levels of both total IgG and IgM in Mgn and Mn breastmilk when compared to Mc. In pups, lymphocyte numbers in the spleens of Pg and Pn were significantly increased compared to Pc. This increase in cellularity was in part attributable to elevated numbers of both CD4+ T cells and B cells, most notable Follicular B cells.

CONCLUSION

Our results indicate that perturbations to maternal gut microbiota dictate neonatal adaptive immunity.

Deep divergence and rapid evolutionary rates in gut-associated Acetobacteraceae of ants

BACKGROUND

Symbiotic associations between gut microbiota and their animal hosts shape the evolutionary trajectories of both partners. The genomic consequences of these relationships are significantly influenced by a variety of factors, including niche localization, interaction potential, and symbiont transmission mode. In eusocial insect hosts, socially transmitted gut microbiota may represent an intermediate point between free living or environmentally acquired bacteria and those with strict host association and maternal transmission.

RESULTS

We characterized the bacterial communities associated with an abundant ant species, Camponotus chromaiodes. While many bacteria had sporadic distributions, some taxa were abundant and persistent within and across ant colonies. Specially, two Acetobacteraceae operational taxonomic units (OTUs; referred to as AAB1 and AAB2) were abundant and widespread across host samples. Dissection experiments confirmed that AAB1 and AAB2 occur in C. chromaiodes gut tracts. We explored the distribution and evolution of these Acetobacteraceae OTUs in more depth. We found that Camponotus hosts representing different species and geographical regions possess close relatives of the Acetobacteraceae OTUs detected in C. chromaiodes. Phylogenetic analysis revealed that AAB1 and AAB2 join other ant associates in a monophyletic clade. This clade consists of Acetobacteraceae from three ant tribes, including a third, basal lineage associated with Attine ants. This ant-specific AAB clade exhibits a significant acceleration of substitution rates at the 16S rDNA gene and elevated AT content. Substitutions along 16S rRNA in AAB1 and AAB2 result in ~10 % reduction in the predicted rRNA stability.

CONCLUSIONS

Combined, these patterns in Camponotus-associated Acetobacteraceae resemble those found in cospeciating gut associates that are both socially and maternally transmitted. These associates may represent an intermediate point along an evolutionary trajectory manifest most extremely in symbionts with strict maternal transmission. Collectively, these results suggest that Acetobacteraceae may be a frequent and persistent gut associate in Camponotus species and perhaps other ant groups, and that its evolution is strongly impacted by this host association.

In vivo and in vitro ketamine exposure exhibits a dose-dependent induction of activity-dependent neuroprotective protein in rat neurons

Anesthetic doses of ketamine induce apoptosis, as well as gene expression of activity-dependent neuroprotective protein (ADNP), a putative homeodomain transcription factor in rat pups (P7). This study investigated if ketamine induced ADNP protein in a dose-dependent manner in vitro and in vivo using primary cultures of cortical neurons and neonatal pups (P7). In vivo immunohistochemistry demonstrated a sub-anesthetic dose of ketamine increased ADNP in the somatosensory cortex (SCC) which was previously identified to be damaged by repeated exposure to anesthetic doses of ketamine. Administration of low-dose ketamine prior to full sedation prevented caspase-3 activation in the hippocampus and SCC. Primary cultures of cortical neurons treated with ketamine (10 μM-10mM) at 3 days-in vitro (3 DIV) displayed a concentration-dependent decrease in expanded growth cones. Furthermore, neuronal production and localization of ADNP varied as a function of both ketamine concentration and length of exposure. Taken together, these data support the model that ADNP induction may be partially responsible for the efficacy of a low-dose ketamine pre-treatment in preventing ketamine-induced neuronal cell death.

Microbial communities associated with wet flue gas desulfurization systems

Flue gas desulfurization (FGD) systems are employed to remove SO(x) gasses that are produced by the combustion of coal for electric power generation, and consequently limit acid rain associated with these activities. Wet FGDs represent a physicochemically extreme environment due to the high operating temperatures and total dissolved solids (TDS) of fluids in the interior of the FGD units. Despite the potential importance of microbial activities in the performance and operation of FGD systems, the microbial communities associated with them have not been evaluated. Microbial communities associated with distinct process points of FGD systems at several coal-fired electricity generation facilities were evaluated using culture-dependent and -independent approaches. Due to the high solute concentrations and temperatures in the FGD absorber units, culturable halothermophilic/tolerant bacteria were more abundant in samples collected from within the absorber units than in samples collected from the makeup waters that are used to replenish fluids inside the absorber units. Evaluation of bacterial 16S rRNA genes recovered from scale deposits on the walls of absorber units revealed that the microbial communities associated with these deposits are primarily composed of thermophilic bacterial lineages. These findings suggest that unique microbial communities develop in FGD systems in response to physicochemical characteristics of the different process points within the systems. The activities of the thermophilic microbial communities that develop within scale deposits could play a role in the corrosion of steel structures in FGD systems.

Role of large-scale velocity fluctuations in a two-vortex kinematic dynamo

This paper presents an analysis of the Dudley-James two-vortex flow, which inspired several laboratory-scale liquid-metal experiments, in order to better demonstrate its relation to astrophysical dynamos. A coordinate transformation splits the flow into components that are axisymmetric and nonaxisymmetric relative to the induced magnetic dipole moment. The reformulation gives the flow the same dynamo ingredients as are present in more complicated convection-driven dynamo simulations. These ingredients are currents driven by the mean flow and currents driven by correlations between fluctuations in the flow and fluctuations in the magnetic field. The simple model allows us to isolate the dynamics of the growing eigenvector and trace them back to individual three-wave couplings between the magnetic field and the flow. This simple model demonstrates the necessity of poloidal advection in sustaining the dynamo and points to the effect of large-scale flow fluctuations in exciting a dynamo magnetic field.

The do-not-resuscitate order: associations with advance directives, physician specialty and documentation of discussion 15 years after the Patient Self-Determination Act

BACKGROUND

Since the passage of the Patient Self-Determination Act, numerous policy mandates and institutional measures have been implemented. It is unknown to what extent those measures have affected end-of-life care, particularly with regard to the do-not-resuscitate (DNR) order.

METHODS

Retrospective cohort study to assess associations of the frequency and timing of DNR orders with advance directive status, patient demographics, physician's specialty and extent of documentation of discussion on end-of-life care.

RESULTS

DNR orders were more frequent for patients on a medical service than on a surgical service (77.34% vs 64.20%, p = 0.02) and were made earlier in the hospital stay for medicine than for surgical patients (adjusted mean ratio of time from DNR orders to death versus total length of stay 0.30 for internists vs 0.21 for surgeons, p = 0.04). 22.18% of all patients had some form of an advance directive in their chart, yet this variable had no impact on the frequency or timing of DNR ordering. Documentation of DNR discussion was significantly associated with the frequency of DNR orders and the time from DNR to death (2.1 days with no or minimal discussion vs 2.8 days with extensive discussion, p<0.01).

CONCLUSIONS

The physician's specialty continues to have a significant impact on the frequency and timing of DNR orders, while advance directive status still has no measurable impact. Additionally, documentation of end-of-life discussions is significantly associated with varying DNR ordering rates and timing.

CT fluoroscopic guidance for percutaneous needle placement into abdominopelvic lesions with difficult access routes

BACKGROUND

We wished to evaluate the utility of computed tomography fluoroscopy (CTF) for guiding percutaneous abdominopelvic biopsies or fluid aspirations that are considered difficult with conventional computed tomographic (CT) guidance.

METHODS

CTF-guided percutaneous biopsy (n = 11) or fluid aspiration (n = 2) was attempted in 13 patients with lesions that were otherwise difficult or potentially unsafe by conventional CT guidance because they were deep to colon, small intestine, or major blood vessels.

RESULTS

Using CTF assistance to guide external compression or needle positioning, appropriate needle placement was performed in 11 patients. Biopsy or aspiration was diagnostic in 10 patients. Needle advancement was not attempted in two patients.

CONCLUSION

CTF appears to be a valuable tool to dynamically assist percutaneous needle placement into lesions that may be considered difficult with standard CT assistance.

Distortion reduction for fast soft straightening of the colon

RATIONALE AND OBJECTIVES

The purpose of this study was to suppress the geometric distortion associated with soft straightening of the colon by moderately adjusting curved cross sections, which is equivalent to appropriately modifying the underlying electrical field.

MATERIALS AND METHODS

A computational mechanism to reduce the geometric distortion associated with soft straightening was developed. Because the cause of distortion is uneven sampling of the colon wall with curved cross sections, the curved cross sections formed according to a numerically simulated electrical field were redistributed in the distortion reduction process. This mechanism can be directly incorporated into a previously published fast soft-straightening algorithm. Simulations were performed to evaluate the effectiveness of the mechanism, and a phantom colon with digitally implanted, spherical polyps was straightened and rendered to visually display the efficacy of the mechanism.

RESULTS

The distortion reduction mechanism was advantageous regarding shape preservation of polyps and alleviated distortion substantially. The mechanism occupied only a small portion of the total processing time.

CONCLUSION

The distortion reduction mechanism can effectively reduce the geometric distortion associated with soft straightening at little computational cost and has potential for use with computed tomographic colonography.

Fast algorithm for soft straightening of the colon

RATIONALE AND OBJECTIVES

In this study, the authors developed a fast algorithm for soft straightening of the colon with computed tomographic data that greatly accelerates the unraveling process based on the interpolation of representative electric force lines.

MATERIALS AND METHODS

Each curved cross section of the colon is defined by electric force lines of a common origin on an electrically charged central path and is constructed by interpolating most of these force lines from a limited number of representative force lines that are traced directly. Both a synthetic colon phantom and a colon in a living patient were used to demonstrate the feasibility of the fast interpolation algorithm compared with direct implementation for soft straightening of the colon.

RESULTS

The interpolation-based soft-straightening algorithm ran approximately 40 times faster than the direct implementation of the electric field-based soft-straightening algorithm.

CONCLUSION

The fast algorithm for soft straightening of the colon has potential for use in computed tomographic colonography.

CT fluoroscopy: technique and utility in guiding biopsies of transiently enhancing hepatic masses

We evaluated a new percutaneous biopsy technique for rapid needle localization and biopsy of transiently enhancing focal hepatic masses. Three biopsies in three patients were completed on lesions 18-22 mm in diameter by using computed tomographic fluoroscopy during intravenous contrast enhancement of the liver. All three biopsies were diagnostic.

Straightening the colon with curved cross sections: an approach to CT colonography

RATIONALE AND OBJECTIVES

The purpose of this study was to straighten digitally and consistently the colon with curved cross sections and to compare the results with planar cross-section-based processing for computed tomographic (CT) colonography.

MATERIALS AND METHODS

In electric field-based straightening, curved cross sections are formed along electric force lines because of electric charges digitally distributed along the colon central path. Four straightening experiments were conducted on CT scans of a colonoscopy phantom. Representative images were studied for polyp detectability and feature distortion. Two further trials involved patient data to demonstrate the clinical feasibility of this method.

RESULTS

In colon straightening with planar sections, a polyp was counted multiple times in both phantom and patient studies where the polyps were in central path turns with substantial curvature. Furthermore, opposite the central path turns, the colon walls were undersampled with planar sections. Straightening with curved sections produced consistent mappings. Image distortion was present in straightening with curved sections, but the conspicuity of polyps was maintained. In the soft-straightening process, trilinear interpolation greatly suppressed the surface- or volume-rendering noise associated with nearest neighbor interpolation.

CONCLUSION

Straightening with curved sections outperforms straightening with planar sections in terms of polyp detectability. This approach eliminates the navigation difficulties of current CT colonography and may have clinical use.

Optimizing contrast enhancement during helical CT of the liver: a comparison of two bolus tracking techniques

OBJECTIVE

The purpose of this study was to evaluate a recently developed hardware and software system for CT scanning that generates images in real time and switches to helical CT scanning by either a visual cue or a region of interest (ROI) amplitude threshold.

SUBJECTS AND METHODS

We randomly and prospectively divided 120 abdominal CT examinations into three groups. Two groups received 75 ml of contrast agent at 1.5 ml/sec. Helical CT scanning began after visualization of the contrast bolus arrival in the hepatic veins (visual cue triggering) (39 patients) or after reaching an ROI threshold (automated ROI threshold triggering) (39 patients). A third group served as a control group (42 patients) and received 150 ml of contrast agent at 1 ml/sec. Quality of hepatic enhancement was assessed objectively and subjectively. Comparisons were made after stratifying each group into three weight classes.

RESULTS

Errors occurred in 12 (31%) of 39 examinations in the group with automated ROI threshold triggering. In that group, we found a significantly (p < .04) lower mean hepatic enhancement in two of three weight categories, and a significantly (p < .04) lower mean subjective scan quality in one of three weight categories, than we found in the group with visual cue triggering.

CONCLUSION

Optimizing portal venous phase helical CT of the liver after a low-volume bolus of contrast agent and an injection rate of 1.5 ml/sec is best achieved by initiating helical CT scanning after visualizing the contrast bolus arrival within the liver rather than after reaching a preset attenuation threshold.

GI tract unraveling with curved cross sections

Gastrointestinal (GI) tract examination with spiral/helical computed tomography (CT) is currently performed by slice-based inspection of axial images. CT colography is a recent advance which allows an intraluminal visualization of the colon, similar to endoscopy. Various rendering algorithms have been developed with promising results, however navigation through the complex, tortuous anatomy of the colon can be time consuming in practice. In this paper, we propose an electrical-field-based method to unravel the convoluted colon, that is, to digitally straighten it with curved cross sections and flatten it over a plane. In our method, electrical charges are simulated along the central colon path. Curved cross sections are defined by the electrical force lines, and lead to consistent unraveling. It is demonstrated with image volumes of two patients that this technique produces a global planar view of complicated colon features with a potential for detection of polyps.

Teaching physical examination of the adult liver with use of real-time sonography

RATIONALE AND OBJECTIVES

The authors developed and evaluated an approach to teaching examination of the liver that incorporates real-time ultrasound (US) imaging as immediate feedback to improve diagnostic accuracy.

MATERIALS AND METHODS

Second-year medical students participating in a course in physical examination were assigned to receive instruction in measuring liver span without (group 1) or with (group 2) real-time sonography. Students from each group attended a practice session given by one of two physicians who were board certified in radiology and internal medicine with special expertise in US. During the practice session for group 2, students were shown the boundaries of the liver of the practice patient with real-time US. Both groups of students then made three measurements each of the liver span of a healthy practice patient and a single healthy test patient without US. The vertical liver span reference standard was determined by one of the authors.

RESULTS

Students in group 2 showed greater accuracy in measuring liver span during both the practice and the test sessions than did students in group 1. The differences were significant for the third practice measurement and all three test measurements (P < .05).

CONCLUSION

The use of real-time US as an aid in teaching physical examination improves students' accuracy in measuring liver size.

Contractions move contents by changing the configuration of the isolated cat stomach

To understand how contractions move gastric contents, we measured, in isolated cat stomachs, the effects of contractions on gastric length, diameters, pressures, and emptying. Movements of the stomach and of gastric contents were monitored by video camera and ultrasound and were related to mechanical events. Based on pressures, we defined the following four phases of contractions: 1) Po, a steady pressure associated with tonic contraction of proximal stomach; 2) P', a pressure wave during which the contraction indents the gastric body; 3) a pressure nadir while the contraction lifts the gastric sinus toward the incisura; and 4) a second pressure wave, P", as the contraction advances through the antrum. In open preparations, liquid output and shortening of the greater curvature are large during Po, stop during P', and resume with P". Contractions generate higher pressures when gastric volume is held steady. Contractions increase wall thickness and decrease gastric diameters at sites they involve and have opposite effects at remote sites. Contractions move the incisura and hence redraw the borders between gastric segments and shift volumes back and forth within the gastric lumen. Contractions furthermore stir up, compress, and disperse particulate beans without moving them to the pylorus. We conclude that gastric contractions 1) reverse changes in gastric length that occur during gastric filling, 2) move gastric contents directly through local contact and indirectly by changing the configuration of the stomach, and 3) interact with structures such as the incisura in retaining and breaking up solid gastric contents.

Normal lower limb venous Doppler flow phasicity: is it cardiac or respiratory?

OBJECTIVE

The purposes of this study were to determine the origin and nature of normal lower limb venous Doppler flow phasicity and to assess normal and respiratory variations.

SUBJECTS AND METHODS

The common femoral veins of 12 healthy volunteers (three men and nine women; age range, 21-50 years; mean, 29 years) were evaluated by detailed spectral Doppler examinations with simultaneous ECG and respirometric tracings. The examinations were performed using a 5- or 7-MHz linear-array transducer with breath held in mid respiration, at the end of deep expiration, at the end of deep inspiration, during Valsalva's maneuver, and during quiet and deep breathing. The tracing obtained during breath-hold in mid respiration was considered the baseline. Tracings obtained during the other respiratory phases were analyzed for changes from the baseline. Doppler tracings were analyzed for phasicity, waveform frequency, components, velocities, velocity ratios, and presence of retrograde flow, all in correlation with simultaneous ECG and respirometric tracings. Tracings were analyzed independently by two observers to assess interobserver variability.

RESULTS

With breath-hold in mid respiration, the common femoral vein Doppler tracings consisted of multiphasic waveforms that had a frequency similar to that of the heart rate. Each waveform consisted of systolic, v, diastolic, and a waves. The systolic wave occurred 0.4 sec later than the QRS complex of the ECG and was always antegrade. The v wave was always retrograde without flow reversal. The diastolic wave was always antegrade. The a wave was always retrograde but showed flow reversal in nine of 12 subjects. The systolic:diastolic velocity ratio ranged from 0.9 to 1.5 (mean, 1.1). The minimum:maximum velocity ratio ranged from -0.4 to 0.2 (mean, -0.15). With breath-hold at the end of expiration, the waveforms became slightly damped, becoming biphasic in five subjects and remaining multiphasic in seven. With breath-hold at the end of inspiration, the waveforms became nonphasic or biphasic in nine and decreased in velocity in 12. With Valsalva's maneuver, flow stopped. With normal respiration, cardiac waveforms were modulated by higher amplitude and less frequent biphasic respiratory waves. The plasticity was equal in two, dominantly cardiac in six, and dominantly respiratory in four. Flow velocity increased with expiration and decreased with inspiration. With deep breathing, the respiratory waves further increased, while the cardiac ones decreased in amplitude. The latter continued to modulate the respiratory phasicity in 10 subjects.

CONCLUSION

During quiet respiration, lower limb venous Doppler tracings consisted of both cardiac and respiratory waveforms. Although respiratory waveforms disappeared when patients held their breath, Doppler tracings continued to be multiphasic and cardiac. Therefore, cardiac phasicity in lower limb venous Doppler tracings does not necessarily indicate cardiac disease. Other respiratory phases can modulate this basic cardiac pattern. Decrease in or loss of phasicity in these waveforms does not always mean proximal obstruction, because it can be caused by respiratory factors. Finally, the presence of minimal cyclic retrograde flow that is 5 cm/sec or less does not necessarily indicate cardiac disease.

Suicides associated with the Jacques Cartier Bridge, Montreal, Quebec 1988-1993: descriptive analysis and intervention proposal

Falls from heights represent an uncommon means of suicide. Regional variations are attributable to the presence of particular sites which attract suicidal individuals. The Jacques Cartier Bridge in Montreal is one such site, though less well known than North American sites such as the Golden Gate Bridge or Niagara Falls. According to Coroner's records, 54 suicides were associated with the bridge for the period 1988 to 1993. All but one of the suicides were the result of jumps from the bridge. The median age of victims was 30 years, and 46 of the victims were male. Bridge-specific verbalization of suicidal intent and prior history of medically diagnosed psychiatric disorders are frequently noted. Based on a review of the effectiveness of preventive measures, we propose limiting access to jumping by means of a fence along the bridge railing.

Volume shifts, unfolding and rolling of haustra in the isolated guinea pig caecum

The large intestine extracts water from chyme and compacts chyme into faecal conglomerates; it is unclear what role the special pockets known as colonic haustra have in these events. Here we monitored the movements of haustra in isolated preparations of guinea pig caecum using videocamera and ultrasound and related them to contractions of muscle flaps and movements of glass beads in haustral pockets. We found that in partially filled caecal loops localized contractions of taeniae shift volume back and forth between adjacent haustra; volume unfolds haustral walls in a characteristic sweep with sequential intrahaustral folds popping out; cyclic contractions and relaxations of the fold then produce the caterpillar-like movement known as haustral rolling; ultrasound showed that haustral rolling made the haustral flow channel narrower and longer as haustral folds increase their height from 7.5 +/- 1.5 mm to 16 +/- 4 mm and their distance from 4.1 +/- 0.2 mm to 7.9 +/- 0.3 mm; luminal contents were alternatively shaken off the haustral wall, whirled around the lumen or left to settle. We also suspended the row of haustra between two taeniae inside a frame and attached flaps of taeniae and haustral folds to strain gauges to record their mechanical activity; both taeniae and haustral folds produced an undulating baseline tension; during rolling, folds produced phasic contractions at 17 +/- 2 cycles min-1 which propagated distally across haustral septa; rolling constantly shuffled around glass beads placed inside the haustra. When we stimulated the intramural nerves to the caecum through bipolar electrodes, all contractile activity was temporarily inhibited and haustral septa flattened; a rebound contraction then propagated aborally from the caecal pole and swept the glass beads ahead of it. Thus, tonic contractions of taeniae shift caecal contents back and forth across haustral septa; expansion of haustra triggers haustral rolling which shuffles contents; both these movements produce local flow within and between haustra which might enhance the separation of solid and liquid colonic contents.

Paraovarian and paratubal cysts: preoperative diagnosis using transabdominal and transvaginal sonography

OBJECTIVE

Paraovarian and paratubal cysts constitute about 10% of adnexal masses. Our purpose was to determine whether pathologically proven examples of these lesions were correctly identified during preoperative transabdominal and transvaginal sonographic evaluations.

METHODS

Between 1990 and 1994, 15 women with 10 paraovarian cysts and 5 paratubal cysts undewent preoperative sonography. The sonograms were performed using transabdominal and transvaginal probes. Mean interval before surgery was 22 days (range: 1-96 days). The sonographic interpretation at the time of the examination was correlated with the pathological findings.

RESULTS

In only 1 of 15 patients was a paraovarian or paratubal cyst suggested before surgery. Paraovarian cysts were misdiagnosed as ovarian cysts. Because of the microscopic size of paratubal cysts in our series, none was diagnosed before surgery and these were usually an incidental finding in patients with ovarian masses.

CONCLUSIONS

In our experience, paraovarian and paratubal cysts are difficult to diagnose before surgery with the use of transabdominal and transvaginal sonography. We speculate that when there is close proximity of a paraovarian cyst to the ovary, an ovarian cystic mass cannot reliably be differentiated from a paraovarian cyst.

Duplex Doppler sonography of changes in portal vein flow in healthy term newborn infants after feeding

To establish reference values for changes in portal venous diameter, angle- corrected maximal flow velocity, and flow in healthy term newborn infants after formula feeding, we studied 20 subjects using duplex Doppler sonography. After feeding, portal venous diameter increased from 3.6 +/- 0.1 (mean +/- standard error of the mean) to 3.9 +/- 0.1 mm at 15 min and decreased to 3.8 +/- 0.1 at 60 min. Maximal flow velocity increased from 24.1 +/- 1.3 cm/s to a maximum of 35.9 +/- 2.4 cm/s at 15 min and decreased to 28.8 +/- 1.5 cm/s at 60 min. Flow increased from 85.0 +/- 7.5 ml/min to a maximum of 153.6 +/- 14.9 ml/min at 15 min with decrease similar to the maximal flow velocity curve. We conclude that formula feeding produces peak portal blood flows of nearly twice the fasting values at 15 min after feeding and returns almost to fasting value by 60 min.

Haustral septations increase axial and radial distribution of luminal contents in glass models of the colon

We used two glass models of the colon to test the hypothesis that luminal septations increase efficiency of flow. Each was a straight glass tube 4 cm in diameter and filled with water. One had four septations narrowing the lumen to 2 cm; the other had no septations. For each run, liquid dye and one solid test particle were placed at one end of the model. A single pressure pulse was applied to the dye and particle. The distance each traveled was compared using analysis of variance. The nonseptated model had poor mixing of dye, and the particle moved only short distances. In the septated model, there was thorough mixing of dye and the particle moved rapidly along what appeared as a central core of high-velocity liquid flow from one septal opening to another. Compared with the nonseptated model, this produced statistically significant increases in the distances traveled by means of 32 (dye) and 90% (particle). Our studies suggest that septations in a tubular organ facilitate intraluminal mixing and flow of liquids and solids.

Laparoscopic partial nephrectomy: initial experience and comparison to the open surgical approach

During an 18-month period, 6 laparoscopic partial nephrectomies were attempted, 4 of which were successful. The surgical technique was modified and improved between cases aided by new laparoscopic instrumentation, such as the argon beam coagulator and the 7.5 MHz. ultrasonic sector scanning system. In a retrospective comparison between laparoscopic and open partial nephrectomy, estimated blood loss was 525 ml. for the former versus 708 ml. for the latter procedure. However, operating time was more than 2 hours longer with the laparoscopic approach. The major advantages of the laparoscopic procedure appear to be a more rapid return to full diet, less postoperative pain and less requirement for parenteral narcotics. Despite the small size of this series and limited followup data, convalescence may be shortened by 4 weeks after laparoscopic partial nephrectomy. Patients with benign diseases of the kidney, especially with a duplicated collecting system, who require partial nephrectomy may be considered candidates for the laparoscopic approach. The advantages to the patient, however, may be offset by the technical demands on the surgeon.

Sonography of acute appendicitis in pregnancy

BACKGROUND

Clinical evaluation of acute appendicitis is difficult in pregnant patients. Delay in diagnosis is associated with increased fetal mortality. The purpose of our study was to assess the value of sonography in the diagnosis of acute appendicitis in pregnant women.

METHODS

We obtained sonograms in 22 pregnant women suspected of acute appendicitis. All sonograms were performed using graded-compression to detect an enlarged appendix. The sonographic criteria for acute appendicitis were detection of a noncompressible blindended and tubular multilayered structure of maximal diameter greater than 6 mm.

RESULTS

The sonographic findings were correlated with surgical findings in seven cases and clinical follow-up in 15 cases. Acute appendicitis was diagnosed by sonography in three of 22 patients, and in all but one was confirmed by surgical and pathologic findings. In the remaining 19 patients, 15 improved on clinical followup; three were shown to have a normal appendix at surgery and one had focal acute inflammation at the tip of the appendix.

CONCLUSIONS

Our experience suggests that graded-compression sonography is a useful procedure in pregnant patients suspected of acute appendicitis and has a similar accuracy as in nonpregnant women, especially in the first and second trimester.

Utility of Tc-99m mebrofenin scintigraphy in the assessment of infantile jaundice

Technetium-99m mebrofenin hepatobillary excretory patterns were assessed in 36 infants with hyperbilirubinemia. Phenobarbital was administered to 22 patients before imaging. Final diagnoses included: intrahepatic cholestasis (14 patients), neonatal hepatitis (nine patients), biliary atresia (eight patients), alpha-1-antitrypsin deficiency (two patients), Alagille's syndrome (two patients), and cystic fibrosis (one patient). No patient with biliary atresia showed bowel activity by 24 hours. Of the 28 infants without biliary atresia, 23 (82%) had bowel activity visualized by 6-8 hours and 26 (90%) had bowel activity by 24 hours. Two had no bowel activity at 24 hours: one had cystic fibrosis and one had neonatal hepatitis. Of the 26 patients with bowel visualization, the time to visualize bowel did not differ between patient groups with and without phenobarbital induction. All of the patients with hepatitis, including those with marked dysfunction, showed good hepatic uptake. Mebrofenin scintigraphy is an important imaging technique in the diagnostic evaluation of infants with hyperbilrubinemia. In addition to biliary atresia, intrahepatic cholestasis due to cystic fibrosis and severe neonatal hepatitis may also cause bowel nonvisualization up to 24 hours. The results of this study suggest phenobarbital induction may not be needed when Tc-99m mebrofenin scintigraphy is used for the assessment of infantile jaundice.

Colonic localization of labeled leukocytes in critically ill patients. Scintigraphic detection of pseudomembranous colitis

This study assesses the causes of colonic localization of labeled white blood cells (WBCs) in critically ill patients who had undergone leukocyte scintigraphy for suspected infection. Forty-two patients showed abdominal or pelvic WBC localization; 20 of these had a pattern of colonic localization, and some also showed a pattern of small bowel activity. Eight of the 20 patients had documented gastrointestinal bleeding. White blood cell scintigraphy in these eight patients showed a pattern of multifocal and/or regional bowel activity that changed in intensity and location from early (3-5-hour) to delayed (18-28-hour) images. In contrast, 5 of the 6 patients with documented pseudomembranous colitis (PMC) showed intense WBC localization involving most of the colon. In 3 of these 5 patients, early and delayed images were acquired and showed a relatively constant pattern of WBC localization. The sixth PMC patient had been treated with vancomycin before leukocyte scintigraphy and showed minimal distal small bowel activity on early images and only mild regional colonic activity on delayed images. As in the patients with gastrointestinal bleeding, the remaining six patients showed either focal or regional activity of variable intensity that changed over time. In critically ill patients, gastrointestinal bleeding and PMC accounted for 14 of the 20 patients in which labeled leukocyte scintigraphy exhibited colonic activity. A pattern of diffuse, intense colonic radiotracer activity which persists from early to delayed imaging strongly suggests the presence of PMC in this patient population.(ABSTRACT TRUNCATED AT 250 WORDS)

Predictive value of normal endovaginal sonography in excluding disease of the female genital organs and adnexa

Endovaginal sonograms of all patients that were interpreted normal during 1990 (12 months) were reviewed. Fifty-nine patients with normal EVS (age range, 18 to 63 years; average, 35 years) were followed either clinically for at least 12 months (average, 23 months) (N = 33) or until a definite diagnosis was established by a definitive procedure (N = 26). Of the 33 patients followed clinically, a definite diagnosis was established in nine, whereas in the remaining patients the symptoms resolved without further evaluation. Of the 26 undergoing definitive procedures, a diagnosis was established (six patients) or the procedure revealed normal pelvic organs (20 patients). A missed diagnosis on EVS was defined as failure to see pathologic lesions in the female pelvic genital organs or adnexa. According to our definition, five lesions were missed by EVS. The negative predictive value from a normal EVS was 92%, using patient outcome as the reference standard.

Strenuous exercise decreases motility and cross-sectional area of human gastric antrum. A study using ultrasound

Gastric emptying in humans is delayed with strenuous exercise. We used ultrasound imaging in six healthy volunteers to determine whether changes in motility and configuration of the gastric outlet contribute to this delay. After fasting, all individuals ingested chicken broth and garbanzo beans. With subjects sitting upright, transverse and longitudinal real-time views of the gastric antrum were recorded on video tape. In the exercise studies, subjects pedaled an ergometer for 10 min to attain a heart rate of 85% predicted maximum. On a different day, all subjects had an identical study without exercise. The order of performance of exercise and no-exercise studies was randomized. After exercise, contraction frequencies and antral areas were significantly reduced compared to the studies without exercise. In addition, after exercise there was closure of the pylorus and tubular narrowing of the gastric antrum. Closure of the pylorus and decreased gastric antral area and motility may be important in explaining the decrease in gastric emptying that occurs with strenuous exercise.

Presacral abscesses: percutaneous transperineal drainage with use of bone landmarks and fluoroscopic guidance

Presacral abscesses developed in two men (aged 59 and 76 years) after abdominoperineal resection. Computed tomography was performed to demonstrate the distance from the abscess to the perineum and the distance of the abscess anterior to the sacrum. Then, lateral and anteroposterior fluoroscopy was performed to guide transperineal drainage catheter placement. No complications occurred, and clinical outcome was successful in both cases.

Cervical cancer: application of MR imaging in radiation therapy

PURPOSE

To evaluate magnetic resonance (MR) imaging in the planning of radiation therapy for patients with cervical cancer.

MATERIALS AND METHODS

MR imaging was performed in 15 patients with predominantly advanced cervical carcinomas. Skin markings of the radiation ports were labeled with MR-detectable tubing and beads to assess the adequacy of port placement. Volume and extent of tumor at MR imaging were compared with those at physical and computed tomographic (CT) examinations.

RESULTS

Tumor involvement of normal structures (parametrium, vagina, endometrium) was more extensive at MR imaging than at clinical examination in six patients (40%) and at CT in five patients (33%), resulting in modification of the radiation fields in eight patients (53%). Tumor size was larger on MR images than at clinical examination in 11 patients (73%).

CONCLUSION

MR imaging can depict tumor volume and better delineate the extent of involvement than physical and CT examination. This can be useful for placement of radiation ports, especially when small boost fields are used.

The configuration of the human gastroduodenal junction in the separate emptying of liquids and solids

BACKGROUND

The stomach separately empties liquids and large particulate solids. The present study aimed to better define the mechanisms responsible for this separate emptying in humans.

METHODS

Real-time ultrasound images of the gastroduodenal junction were tape-recorded in normal volunteers after they ingested a test meal consisting of beans and chicken broth.

RESULTS

During early emptying, beans were retained along the gastric greater curve as it bulged caudally. When the pylorus was open, liquids flowed over the beans into the duodenum. Emptying of the occasional bean that appeared in the antrum was blocked by closure of the pylorus. Later, the antrum was tubular in shape with reduced area of cross section, yet the percent narrowing of the lumen with each contraction remained constant. Beans were now in close contact with the contracting antral wall and were transformed into small particles. Only in this state were solids allowed through the pylorus.

CONCLUSIONS

Mechanisms by which the human stomach "sieves" liquids from solids include (1) sedimentation of solids in the dependent portion of the stomach, while liquids are "decanted" into the duodenum in early emptying; (2) blockade of large particles from entering the duodenum by closure of the pylorus; and (3) grinding of large particles by the gastric antrum in late emptying.

Midgut volvulus as a complication of intestinal malrotation in adults

Seven adults with midgut volvulus as a complication of malrotation are presented. All patients were men with an average age of 33 years. Four presented with long histories of intermittent abdominal pain. In three patients, the twisted, corkscrew appearance of the barium column in the duodenum and proximal jejunum in an upper gastrointestinal series made the diagnosis. In the remaining patient, small-bowel follow-through performed three years before surgery showed intestinal malrotation. Three patients presented with the acute onset of severe abdominal pain. Plain films showed small-bowel obstruction and pneumatosis intestinalis in two patients and only nearly complete small-bowel obstruction in the third. Barium studies were not done in this group because of the need to proceed to exploratory laparotomy and the risk of perforation. In one patient, abdominal angiography suggested the diagnosis by showing abnormal courses of the mesenteric vessels to the volvulized segment of small bowel. All three of these patients showed ischemic segments of bowel at laparotomy.

Contraction and accommodation of guinea pig duodenum in vitro

Because duodenal resistance to gastric emptying depends in part on duodenal capacity, we examined the changes of duodenal diameter, length, and luminal pressure that occur in response to injection of bolus volumes. Filling the duodenum led to a powerful, nonpropagating contraction of the duodenum. After the end of filling, sequential duodenal segments widened and duodenal pressure and length returned to baseline; i.e., there was accommodation. Accommodation was volume dependent and ceased at volumes greater than or equal to 1.2 ml. The entire duodenum unfolded almost immediately and the initial increase of pressure and length was abolished when the duodenal musculature was inhibited by exposure to tetrodotoxin or to Ca(2+)-free solution. Pressures and pressure accommodation were larger, occurred earlier, and lasted longer when the duodenal musculature was stimulated by exposure to carbachol. Filling of the duodenum from the distal end led to rapid distribution of the bolus through the duodenum and to accommodation similar to that seen with proximal filling. However, phasic duodenal contractions were less powerful on distal than on proximal injection. Spontaneous phasic contractions of the duodenum were accompanied by a similar sequence of changes in duodenal configuration as was observed with filling. We conclude that 1) the duodenum adjusts the tension of its walls at small volumes, and beyond this is fairly rigid; 2) filling the duodenum triggers contraction responses similar to those that occur with spontaneous contractions; and 3) the direction from which the duodenum is filled does not affect its accommodation. We postulate that the filling response of the duodenum may critically affect gastric emptying.