Soil Methane and Carbon Dioxide Fluxes from Cropland and Riparian Buffers in Different Hydrogeomorphic Settings

Riparian buffers contribute to the mitigation of nutrient pollution in agricultural landscapes, but there is concern regarding their potential to be hot spots of greenhouse gas production. This study compared soil CO and CH fluxes in adjacent crop fields and riparian buffers (a flood-prone forest and a flood-protected grassland along an incised channel) and examined the impact of water table depth (WTD) and flood events on the variability of gas fluxes in riparian zones. Results showed significantly ( < 0.001) higher CO emission in riparian areas than in adjoining croplands (6.8 ± 0.6 vs. 3.6 ± 0.5 Mg CO-C ha yr; mean ± SE). Daily flux of CO and soil temperature were significantly related ( < 0.002), with Q values ranging between 1.75 and 2.53. Significant relationships ( < 0.05) were found between CH daily flux and WTD. Flood events resulted in enhanced CH emission (up to +44.5 mg CH-C m d in a swale) under warm soil conditions (>22°C), but the effect of flooding was less pronounced in early spring (emission <1.06 mg CH-C m d), probably due to low soil temperature. Although CH flux direction alternated at all sites, overall the croplands and the flood-affected riparian forest were CH sources, with annual emission averaging +0.04 ± 0.17 and +0.92 ± 1.6 kg CH-C ha, respectively. In the riparian forest, a topographic depression (<8% of the total area) accounted for 78% of the annual CH emission, underscoring the significance of landscape heterogeneity on CH dynamics in riparian buffers. The nonflooded riparian grassland, however, was a net CH sink (-1.08 ± 0.22 kg CH-C ha yr), probably due to the presence of subsurface tile drains and a dredged/incised channel at that study site. Although these hydrological alterations may have contributed to improvement in the CH sink strength of the riparian grassland, this must be weighed against the water quality maintenance functions and other ecological services provided by riparian buffers.

Timed barium esophagram in achalasia types

Relationships of timed barium esophagram (TBE) findings to achalasia types defined by high-resolution manometry (HRM) have not been elucidated. Therefore, we correlated preoperative TBE and HRM measurements in achalasia types and related these to patient symptoms and prior treatments. From 2006 to 2013, 248 achalasia patients underwent TBE and HRM before Heller myotomy. TBE height and width were recorded at 1 and 5 minutes; HRM measured lower esophageal sphincter mean basal pressure, integrated relaxation pressure (IRP), and mean esophageal body contraction amplitude. Achalasia was classified into types I (25%), II (65%), and III (9.7%). TBE height at 5 minutes was higher for I (median 8 cm; interquartile range 6-12) and II (8 cm; 8-11) than for III (1 cm; 0-7). TBE width at 5 minutes was widest (3 cm; 2-4), narrower in II (2 cm; 2-3), and narrowest in I (1 cm; 0-2), P < 0.001. Volume remaining at 1 and 5 minutes was lower in III (1 m(2) ; 0-16) than I (42 m(2) ; 17-106) and II (39 m(2) ; 15-60), highlighting poorer emptying of I and II. Increasing TBE width correlated with deteriorating morphology and function from III to II to I. Symptoms poorly correlated with TBE and HRM. Prior treatment was associated with less regurgitation, faster emptying, and lower IRP. Although TBE and HRM are correlated in many respects, the wide range of their measurements observed in this study reveals a spectrum of morphology and dysfunction in achalasia that is best characterized by the combination of these studies.

Nitrous oxide emission from cropland and adjacent riparian buffers in contrasting hydrogeomorphic settings

Riparian buffers are important nitrate (NO) sinks in agricultural watersheds, but limited information is available regarding the intensity and control of nitrous oxide (NO) emission from these buffers. This study monitored (December 2009-May 2011) NO fluxes at two agricultural riparian buffers in the White River watershed in Indiana to assess the impact of land use and hydrogeomorphologic (HGM) attributes on emission. The study sites included a riparian forest in a glacial outwash/alluvium setting (White River [WR]) and a grassed riparian buffer in tile-drained till plains (Leary Weber Ditch [LWD]). Adjacent corn ( L.) fields were monitored for land use assessment. Analysis of variance identified season, land use (riparian buffer vs. crop field), and site geomorphology as major drivers of NO fluxes. Strong relationships between N mineralization and NO fluxes were found at both sites, but relationships with other nutrient cycling indicators (C/N ratio, dissolved organic C, microbial biomass C) were detected only at LWD. Nitrous oxide emission showed strong seasonal variability; the largest NO peaks occurred in late spring/early summer as a result of flooding at the WR riparian buffer (up to 27.8 mg NO-N m d) and N fertilizer application to crop fields. Annual NO emission (kg NO-N ha) was higher in the crop fields (WR: 7.82; LWD: 6.37) than in the riparian areas. A significant difference ( < 0.02) in annual NO emission between the riparian buffers was detected (4.32 vs. 1.03 kg NO-N ha at WR and LWD, respectively), and this difference was attributed to site geomorphology and flooding (WR is flood prone; no flooding occurred at tile-drained LWD). The study results demonstrate the significance of landscape geomorphology and land-stream connection (i.e., flood potential) as drivers of NO emission in riparian buffers and therefore argue that an HGM-based approach should be especially suitable for determination of regional NO budget in riparian ecosystems.

Coronary angiographic profile in bangladeshi patients with metabolic syndrome and ischemic heart disease

The metabolic syndrome, which is characterized by a constellation of fasting hyperglycemia, hypertriglyceridemia, low HDL cholesterol, hypertension, and/or abdominal obesity, is a risk factor for the development of coronary artery disease (CAD) and cardiovascular events. We evaluated interrelationships between angiographic CAD and the metabolic syndrome, in 478 patients who were referred for coronary angiography to evaluate suspected myocardial ischemia in the department of cardiology of BSMMU between June 2007 and May 2008. We applied the criteria for the metabolic syndrome proposed by ATP III guideline. Study populations were divided into two groups on the basis of presence or absence of metabolic syndrome. Age was similar in both groups. Body mass index (BMI) was higher (26.22 ± 1.94 vs. 22.07 ± 1.55) in metabolic syndrome group (p ≤ 0.0001). All parameters, waist circumference (103.16 ± 10.21 vs. 91.45 ± 7.61) cm, blood pressure both systolic (141.34 ± 21.49 vs. 127.94 ± 13.01) and diastolic (86.8 5 ± 8.42 vs. 79.28 ± 7.77) mm of Hg, serum triglyceride (248.32 ± 77.88 vs. 128.35 ± 19.00)mg/dl, fasting blood glucose (125.40 ± 22.86 vs. 95.65 ± 10.63)mg/dl were significantly higher in metabolic syndrome group (p value=0.0001), whereas HDL (33.10 ± 6.55 vs. 39.30 ± 6.17)mg/dl was lower (p value = 0.0001). More subjects in metabolic syndrome were having type B (55.60% vs. 31.00%) and type C (9.50% vs. 2.70%) lesion as compared to non-metabolic syndrome group. Involvement of left main artery was more (4.80% vs. 0.90%) in metabolic syndrome group. Metabolic syndrome has primary predictive ability for CAD. A metabolic profile should form part of the risk assessment in all patients with coronary disease, not just those who are obese.

Biological effects of marine contaminated sediments on Sparus aurata juveniles

Chemical analysis of the compounds present in sediment, although informative, often is not indicative of the downstream biological effects that these contaminants exert on resident aquatic organisms. More direct molecular methods are needed to determine if marine life is affected by exposure to sediments. In this study, we used an aquatic multi-species microarray and q-PCR to investigate the effects on gene expression in juvenile sea bream (Sparus aurata) of two contaminated sediments defined as sediment 1 and 2, respectively, from marine areas in Northern Italy. Both sediments affected gene expression as evidenced by aquatic multi-species microarray analysis and q-PCR. Exposure of S. aurata juveniles to sediment 1 and sediment 2 altered expression of genes that are biomarkers for endocrine disruption. There were differences between the effects of sediment 1 and sediment 2 on gene expression in S. aurata juveniles indicating that the chemicals in the two sediments had different physiological targets. These results suggest that the classification of sediment solely on the basis of specific chemical profiles is inadequate, and not a true indicator of its potential to cause harmful effects. Our data also indicate that integration of physiochemical analysis and bioassays for monitoring the downstream harmful effects on aquatic organisms are required to gain a complete understanding of the effects of sediment on aquatic life.

Variation of the genetic expression pattern after exposure to estradiol-17beta and 4-nonylphenol in male zebrafish (Danio rerio)

There is much concern about the increasing presence in the environment of synthetic chemicals that are able to disrupt the endocrine system. Among these compounds, 4-nonylphenol (4-NP) is one of the most studied xenoestrogens, due to its widespread accumulation in water sediment and consequent presence in fatty acid of aquatic organisms. Here, we have used a zebrafish microarray representing 16,399 genes to study the effects of 4-NP and estradiol-17beta (E2) in adult male zebrafish in order to elucidate the mechanism of action of 4-NP compared with that of E2. The microarray results showed that both 4-NP and E2 induced a strong expression of vitellogenin (VTG), the sex related precursor of the yolk proteins in oviparous vertebrates. Both treatments induced elevated protein turnover upregulating genes involved in proteolysis and those that are constituents of the ribosome. Many genes regulated by 4-NP and E2 are involved in energy metabolism, oxidative stress defense mechanisms, xenobiotic metabolism, and lipid metabolism. A different pattern of expression in the two treatments was found for genes involved in oxidative stress, since E2 seems to induce the mechanism of detoxification, while 4-NP seems to inhibit this protective mechanism of the cell. Overall, these findings demonstrate that the microarray approach can contribute significantly to the understanding of expression patterns induced by E2 and 4-NP in male zebrafish. The results also demonstrate that 4-NP is able to act through an alternative pattern to that of estradiol-17beta, modulating the expression of the same genes in a different manner.

Computer-aided detection (CAD) for CT colonography: a tool to address a growing need

Colorectal cancer is the third most common cancer in both men and women. It is estimated that in 2004, nearly 147,000 cases of colon and rectal cancer will be diagnosed in the USA, and approximately 57,000 people would die from the disease; however, only 44% of the eligible population undergoes any type of colorectal cancer screening. Many reasons have been identified for non-compliance, with key ones being patient comfort, bowel preparation and cost. Virtual colonoscopy derived from computed tomography (CT) images is gaining broader acceptance as a screening method for colorectal neoplasia. Our research suggests that computer-aided detection (CAD) as a second reader has great potential in improving polyp detection. The ColonCAD prototype presented in this paper was developed and tested on cases representative of the variability and quality in true clinical practice. Results of this study with 150 patients demonstrate that: the developed algorithm generalises well: the sensitivity for polyps > or = 6 mm is on average 90%; and the median false positive rate is a manageable 3 per volume.

Albumin, steroid hormones and the origin of vertebrates

Albumin, the major serum protein, binds a wide variety of lipophilic compounds including steroids, other lipophilic hormones and various phytochemicals and xenobiotics that bind to receptors for steroids and other lipophilic hormones. Despite albumin's low affinity (K(d) approximately 10(-4) M to 10(-6) M) for these lipophilic compounds, the high concentration of albumin in serum makes this protein a major carrier of steroids and lipophilic hormones and a regulator of their access to receptors. Albumin also functions as a sink for xenobiotics, diminishing the binding of xenobiotics to hormone receptors and other cellular proteins. This protects animals from endocrine disruption by xenobiotics. We propose that these properties of albumin were important in protochordates and primitive vertebrates, such as jawless fish, about 600 to 530 million years ago, just before and during the Cambrian period. It is at that time that the ancestral receptors of adrenal and sex steroids - androgens, estrogens, glucocorticoids, mineralocorticoids, and progestins - arose in multicellular animals. Albumin regulated access of steroids to their receptors, as well as protecting animals from endocrine disruptors, such as phytochemicals, fungal chemicals and phenolics, and other chemicals formed at hydrothermal vents by geochemical processes. Thus, animals in which albumin expression was high had a selective advantage in regulating the steroid response and avoiding endocrine disruption by xenobiotics.

Recent insights into the origins of adrenal and sex steroid receptors

The recent cloning by Thornton (2001) of estrogen, progesterone and corticoid receptors from lamprey provides important insights into the early evolution of adrenal and sex steroid receptors and an opportunity to elucidate the ancient steroids that regulated gene transcription. Inclusion of lamprey sequences in a steroid receptor phylogeny indicates that the estrogen receptor is the most ancient of these receptors, followed by the progesterone receptor and the corticoid receptor. Thornton proposed that estradiol was the earliest of the steroids to activate a steroid receptor. An alternative hypothesis is that a steroid in the Delta(5) pathway activated the ancestral estrogen receptor.

Timed barium oesophagram: better predictor of long term success after pneumatic dilation in achalasia than symptom assessment

BACKGROUND

Symptom relief post pneumatic dilation is traditionally used to assess treatment success in achalasia patients. Recently, we showed that symptom relief and objective oesophageal emptying are concordant in about 70% of patients, while up to 30% of achalasia patients report near complete symptom relief despite poor oesophageal emptying of barium.

AIMS

We now report the results of long term clinical follow up in these two groups of achalasia patients, assessing differences in symptomatic remission rates.

METHODS

Achalasia patients undergoing pneumatic dilation since 1995 were evaluated both symptomatically and objectively at regular intervals. Pre and post dilation symptoms were recorded. Barium column height was measured five minutes after ingesting a fixed volume of barium per patient to assess oesophageal emptying. Patients who initially reported near complete symptom relief were divided into two groups based on objective findings on barium study: (1) complete oesophageal emptying (concordant group), and (2) poor oesophageal emptying (discordant group). Patients were followed prospectively for symptom recurrence.

RESULTS

Thirty four patients with complete symptom relief post pneumatic dilation were identified. In 22/34 (65%) patients, the degree of symptom and barium height improvements was similar (concordant group). In 10/34 (30%) patients, there was < 50% improvement in barium height (discordant group). Significantly (p<0.001) more discordant (9/10; 90%) than concordant (2/22; 9%) patients failed therapy at the one year follow up. Seventeen of 22 (77%) concordant patients were still in remission while all discordant patients had failed therapy by six years of follow up. Length of time in symptom remission (mean (SEM)) post pneumatic dilation was significantly (p=0.001) less for the discordant group (18.0 (3.6) months) compared with the concordant group (59.0 (4.8) months).

CONCLUSIONS

(1) Poor oesophageal emptying is present in nearly 30% of achalasia patients reporting complete symptom relief post pneumatic dilation. (2) The majority (90%) of these patients will fail within one year of treatment. (3) Timed barium oesophagram is an important tool in the objective evaluation of achalasia patients post pneumatic dilation.

Deletion of 12 carboxyl-terminal residues from pig 3alpha/beta,20beta-hydroxysteroid dehydrogenase affects steroid metabolism

Pig 3alpha/beta,20beta-hydroxysteroid dehydrogenase (3alpha/beta,20beta-HSD) is 80-85% identical to human, rat, and mouse carbonyl reductases. However, pig 3alpha/beta,20beta-HSD contains an extra 12 amino acids at its COOH-terminus that these other mammalian carbonyl reductases lack. We constructed a pig 3alpha/beta,20beta-HSD mutant, G278opal, which lacks these amino acids and found that compared to wild-type 3alpha/beta,20beta-HSD, G278opal has a 10-fold lower catalytic efficiency for testosterone and progesterone. G278opal also has lower 3alpha- and 20beta-reductase and increased 3beta-reductase activity compared to wild-type 3alpha/beta,20beta-HSD. Binding of NADPH to G278opal was similar to that of wild-type 3alpha/beta,20beta-HSD. The recently determined three-dimensional structure of 3alpha/beta,20beta-HSD, without a steroid substrate, shows the 12 COOH-terminal amino acids in a random configuration. Our data indicate that the 12 COOH-terminal amino acids have a role in steroid metabolism suggesting that binding of steroid to wild-type 3alpha/beta,20beta-HSD induces a conformational change in which the 12 COOH-terminal amino acids interact with the steroid substrate.

Radiologic evaluation of the esophagus: methods and value in motility disorders and GERD

The barium esophagram is an essential component in the workup of a patient with dysphagia and gastroesophageal reflux disease, especially when considering antireflux surgery or after such surgery. The examination requires a flexible approach with an emphasis on the motility portion of the examination. When properly performed, the examination should identify the following: normal or impaired esophageal emptying; normal or abnormal motility; the presence and type of hiatal hernia; the presence of a distal stricture or mucosal ring; and in many instances, the presence of gastroesophageal reflux. In patients after antireflux surgery, the examination should identify the following: normal of impaired esophageal emptying; normal or abnormal motility; the location, tightness, and length of the fundoplication; the presence of a recurrent hernia; and the presence of gastroesophageal reflux.

Hydroxysteroid dehydrogenases: ancient and modern regulators of adrenal and sex steroid action

The adrenal and sex steroids receptor clade arose from an ancestral nuclear receptor in a primitive vertebrate at least 540 million years ago during the early Cambrian. At that time, these receptors had less specificity for their canonical ligands than their descendents in mammals have, which raises the question of how specificity for responses to different steroids was regulated. We propose that hydroxysteroid dehydrogenases that metabolized functional groups at different sites on steroids (e.g. C3, C11, C17 and C20) had a key role in providing specificity for steroid regulation of gene transcription in primitive vertebrates. Later, with increased physiological complexity in land animals due to innovations such as the placenta, hydroxysteroid dehydrogenases were recruited for new roles in regulating steroid-mediated physiological responses. Hydroxysteroid dehydrogenases in fish, amphibia and mammals are likely have different affinities for some xenobiotics, which needs to be considered in evaluating their hazards as endocrine disruptors.

Adrenal and sex steroid receptor evolution: environmental implications

The nuclear receptor family responds to a diverse group of ligands, including steroids, retinoids, thyroid hormone, prostaglandins and fatty acids. Previous sequence analyses of adrenal and sex steroid receptors indicate that they form a clade separate from other nuclear receptors. However, the relationships of adrenal and sex steroid receptors to each other and to their ancestors are not fully understood. We have used new information from androgen, estrogen, mineralocorticoid and progesterone receptors in fish to better resolve the phylogeny of adrenal and sex steroid receptors. Sequence divergence between fish and mammalian steroid receptors correlates with differences in steroid specificity, suggesting that phylogeny needs to be considered in evaluating the endocrine effects of xenobiotics. Among the vertebrate steroid receptors, the most ancient is the estrogen receptor. The phylogeny indicates that adrenal and sex steroid receptors arose in a jawless fish or a protochordate and that changes in the sequence of the hormone-binding domain have slowed considerably in land vertebrates. The retinoid X receptor clade is closest to the adrenal and sex steroid receptor clade. Retinoid X receptor is noteworthy for its ability to form dimers with other nuclear receptors, an important mechanism for regulating the action of retinoid X receptor and its dimerization partners. In contrast, the adrenal and sex steroid receptors bind to DNA as homodimers. Moreover, unliganded adrenal and sex steroid receptors form complexes with heat shock protein 90. Thus, the evolution of adrenal and sex steroid receptors involved changes in protein-protein interactions as well as ligand recognition.

Evolution of 17beta-hydroxysteroid dehydrogenases and their role in androgen, estrogen and retinoid action

17beta-Hydroxysteroid dehydrogenases (17beta-HSDs) regulate androgen and estrogen concentrations in mammals. By 1995, four distinct enzymes with 17beta-HSD activity had been identified--17beta-HSD-types 1 and 3, which, in vivo, are NADPH-dependent reductases; and 17beta-HSD-types 2 and 4, which, in vivo, are NAD(+)-dependent oxidases. Since then, six additional enzymes with 17beta-HSD activity have been isolated from mammals. With the exception of 17beta-HSD-type 5, which belongs to the aldoketo-reductase (AKR) family, these 17beta-HSDs belong to the short chain dehydrogenase/reductase (SDR) family. Several 17beta-HSDs appear to be examples of convergent evolution. That is, 17beta-HSD activity arose several times from different ancestors. Some 17beta-HSDs share a common ancestor with retinoid oxido-reductases and have retinol dehydrogenase activity. 17beta-HSD-types 2, 6 and 9 appear to have diverged from ancestral retinoid dehydrogenases early in the evolution of deuterostomes during the Cambrian, about 540 million years ago. This coincided with the origin of nuclear receptors for androgens and estrogens suggesting that expression of 17beta-HSDs had an important role in the early evolution of the physiological response to androgens and estrogens.

Imaging strategies in the pregnant cancer patient

This review summarizes the pertinent issues of radiation exposure to the developing fetus and the existing imaging techniques available to detect neoplastic disease spread of the common malignancies in women of reproductive age (breast cancer, cervical carcinoma, Hodgkin's disease, and melanoma). The standard radiologic work-up for assessing disease extent is reviewed and the pros and cons of these various imaging modalities are discussed with regard to the potential deleterious effects on the mother and fetus. Reasonable alternatives to the standard protocols for documenting extent of disease for these neoplasms are proposed. Usually a pregnant cancer patient can be safely and reasonably staged with imaging. Magnetic resonance (MR) imaging will most often be the procedure of choice because it does not use ionizing radiation. Specialized, focused questions such as sentinel lymph node detection may require limited exposure to ionizing radiation, which will not expose the fetus to a significant dose. While a standard chest x-ray does involve ionizing radiation, it does not expose the fetus to significant radiation.

Timed barium esophagogram: A simple physiologic assessment for achalasia

OBJECTIVE

Success of achalasia therapy is difficult to determine because repeated physiologic study is impractical and symptoms are subjective. Timed barium esophagography directly measures esophageal emptying and is simple to perform. This study (1) evaluates the assessment of myotomy by timed barium esophagography and (2) compares it with premyotomy and postmyotomy symptoms.

METHODS

Fifty patients ingested 250 mL low-density barium and had upright films at 1, 2, and 5 minutes premyotomy. Forty-five underwent repeat timed barium esophagography 8 weeks (median) postmyotomy. Premyotomy and postmyotomy height and width of the barium column were compared and related to symptoms.

RESULTS

At 1, 2, and 5 minutes premyotomy, median barium column height was 19, 17, and 15 cm, and width was 5.2, 4.8, and 4.5 cm, respectively. Surgery reduced these to 7.0, 5.0, and 1.0 cm and to 3.5, 3.0, and 1.0 cm, respectively (P <.001). Postmyotomy complete esophageal emptying was seen in 29%, 36%, and 49% at 1, 2, and 5 minutes. Postmyotomy height was unrelated (r approximately 0.2) to premyotomy height but was directly related to premyotomy width (r = 0.3-0.5; P <.05); postmyotomy width was directly related to premyotomy width (r approximately 0.6; P <.001). Premyotomy dysphagia was more severe when little change in width occurred from 1 to 5 minutes (r = 0.26, P =.07). Premyotomy regurgitation was more severe the higher the barium column (r approximately 0.4, P <.007). Surgery relieved symptoms in the majority of patients (grade 2-5 dysphagia from 72% to 4%, grade 2-5 regurgitation from 79% to 4%). Postmyotomy symptoms were unrelated to the timed barium esophagogram.

CONCLUSIONS

(1) The timed barium esophagogram gives objective confirmation of successful myotomy. (2) Symptoms are unreliable in assessing esophageal emptying.

Feasibility of instructing radiology technologists in the performance of gastrointestinal fluoroscopy

OBJECTIVE

We sought to determine if dedicated gastrointestinal technologists could be trained to properly perform esophagography and double-contrast barium enema examinations.

SUBJECTS AND METHODS

Ninety-four patients undergoing double-contrast barium enema examinations and 123 patients undergoing esophagographic examinations were included in the study. The study was conducted over a 4-month period, with examinations performed by eight gastrointestinal technologists, 10 radiology residents, and four staff radiologists. Four random lists were generated for each set of examinations. Each staff gastrointestinal radiologist, who was unaware of who had performed the examination, independently scored the representative radiographs.

RESULTS

For the double-contrast barium enema examinations, no statistically significant differences were found between the technologists and residents for amount of barium used, degree of distention, cecal opacification, and quality of spot radiographs. The technologist-performed examinations had a statistically significant lower mean fluoroscopy time (3.2 min, compared with 4.0 min for staff radiologists and 5.7 min for residents). For the esophagrams, no statistically significant differences between technologists and residents were found for single-contrast esophagrams; radiographs of the gastric cardia; assessment of motility, reflux, and transit of a solid bolus; and fluoroscopy time. Double-contrast esophagrams obtained by technologists received a better mean score than did those of the residents.

CONCLUSION

Radiology technologists can be trained to perform high-quality esophagography and double-contrast barium enema examinations without an unacceptably high radiation dose.

Mutation of threonine-241 to proline eliminates autocatalytic modification of human carbonyl reductase

Carbonyl reductase catalyses the reduction of steroids, prostaglandins and a variety of xenobiotics. An unusual property of human and rat carbonyl reductases is that they undergo modification at lysine-239 by an autocatalytic process involving 2-oxocarboxylic acids, such as pyruvate and 2-oxoglutarate. Comparison of human carbonyl reductase with the pig enzyme, which does not undergo autocatalytic modification, identified three sites, alanine-236, threonine-241 and glutamic acid-246, on human carbonyl reductase that could be important in the reaction of lysine-239 with 2-oxocarboxylic acids. Mutagenesis experiments show that replacement of threonine-241 with proline (T241P) in human carbonyl reductase eliminates the formation of carboxyethyl-lysine-239. In contrast, the T241A mutant has autocatalytic activity similar to wild-type carbonyl reductase. The T241P mutant retains catalytic activity towards menadione, although with one-fifth the catalytic efficiency of wild-type carbonyl reductase. Replacement of threonine-241 with proline is likely to disrupt the local structure near lysine-239. We propose that integrity of this local environment is essential for chemical modification of lysine-239, but not absolutely required for carbonyl reductase activity.

Three-dimensional model of human TIP30, a coactivator for HIV-1 Tat-activated transcription, and CC3, a protein associated with metastasis suppression

Human TIP30 is a cofactor that specifically enhances human immunodeficiency virus-1 (HIV-1) Tat-activated transcription. The sequence of TIP30 is identical to that of CC3, a protein associated with metastasis suppression. TIP30/CC3 is a member of the short-chain dehydrogenases/reductases (SDR) family. Of the several experimentally determined SDR structures, Escherichia coli uridine diphosphate (UDP) galactose-4 epimerase is most similar to TIP30/CC3. Because the direct sequence similarity between TIP30/CC3 and E. coli UDP galactose-4 epimerase is low, we used the transitive nature of homology and employed two Aquifex aeolicus proteins as intermediaries in the homology modeling process. Comparison of our structural model with that of known SDRs reveals that TIP30/CC3 contains several well-conserved features, including a beta alpha beta fold at the amino terminus, which we predict binds NADP(H). TIP30/CC3 contains characteristic motifs at the catalytic site of SDRs, including a serine, tyrosine, and lysine that are important in catalyzing hydride transfer between substrate and cofactor. We also predict that a unique 20-amino acid sequence found at the amino terminus is an alpha-helix. Because this region contains several positively and negatively charged amino acids, it may dock TIP30/CC3 to other proteins. Our structural model points to this alpha-helix and the SDR-like part of TIP30/CC3 for mutagenesis experiments to elucidate its role in HIV-1 Tat-activated transcription, metastasis suppression, and other cellular functions.

Adrenal mass evaluation in patients with lung carcinoma: a cost-effectiveness analysis

OBJECTIVE

This study evaluates the cost-effectiveness of various imaging and biopsy strategies for characterizing adrenal masses in patients with newly diagnosed non-small cell carcinoma of the lung.

MATERIALS AND METHODS

A decision-analysis model was used to compare the cost-effectiveness of nine strategies. Initial imaging included unenhanced CT using an adenoma or nonadenoma threshold of 0 or 10 H or in- and opposed-phase MR imaging. When initial imaging did not confirm an adenoma, CT-guided biopsy or subsequent imaging was performed. Medicare reimbursement was used as a surrogate of cost. Net costs were calculated as the difference in costs between two limbs of the decision tree. Net benefits were calculated as the difference between strategies and were calculated for life expectancy in years. MR imaging, CT, and biopsy accuracy, average life expectancy, and surgical mortality rates were based on the literature.

RESULTS

The base case analysis determined that the most cost-effective strategy was CT with an adenoma or nonadenoma threshold of 10 H followed by MR imaging, if necessary. CT with a threshold of 0 H followed by biopsy, if necessary, was the least costly. The incremental cost-effectiveness ratio between these two strategies was $16,370 per year of life gained.

CONCLUSION

Unenhanced CT using a 10 H threshold followed by MR imaging, if needed, was the most cost-effective strategy for evaluating an adrenal mass in a patient with newly diagnosed non-small cell lung cancer.

Knowledge and attitudes of health care social workers regarding advance directives

This cross sectional investigation describes the knowledge and attitudes of health care social workers regarding advance directives and explores factors that influence them. As major contributors to quality patient care, the level of knowledge and attitudes held by health care social workers regarding health care policy mandates are important. Mail survey methods were used to collect data from a systematic random sample (n = 324) of social workers throughout one mid-western state. Results indicate that the majority of health care social workers have high to moderate levels of knowledge about advance directives and hold positive attitudes regarding the policy. Social workers with more experience working with the elderly had higher levels of knowledge. Those employed in nursing homes and hospice settings had more positive attitudes than did those working in other health care facilities.

Esophageal diverticula: patient assessment

Esophageal diverticula are best classified by their anatomic location: pharyngoesophageal (Zenker's diverticula), midthoracic, and epiphrenic. Most diverticula result from esophageal motility disorders. Although some patients are asymptomatic and diverticula are incidental findings, most patients are symptomatic. Dysphagia, regurgitation, and pain are common complaints, however, symptoms are often nonspecific and may be the result of an associated esophageal motility disorder. Contrast radiography is the prime diagnostic tool; evaluation of the diverticulum, associated esophageal abnormalities, and complications are assessed by a barium esophogram. Esophagoscopy adds little to the evaluation of the diverticulum but may be indicated in the assessment of other esophageal abnormalities. Motility studies, which may be difficult or hazardous to perform, are of little use in the diagnosis and treatment of Zenker's diverticula. Manometric evaluation of midthoracic or epiphrenic diverticula usually show an associated motility disorder and may influence treatment decisions.

Midthoracic esophageal diverticula

Periesophageal inflammation, most commonly secondary to tuberculosis, was a frequent cause of midthoracic diverticula. Today, the majority of these diverticula are the result of esophageal motility disorders. Although many patients are asymptomatic, it is the underlying motility disturbances that produce most symptoms. A barium esophagogram is the best study to show midthoracic diverticula. Esophageal manometry may be difficult to perform because of the obstruction of passage of the motility catheter by the diverticulum, but it is useful in defining the cause of the diverticulum and directing therapy. Esophagoscopy is helpful in the assessment of complications or associated esophageal abnormalities. It adds little to the evaluation of the diverticulum. In patients requiring surgery, a diverticulectomy with a myotomy performed on the esophageal wall opposite the diverticulum is the preferred treatment. Lesser procedures have been reported to be successful in select patients.

Assessment of esophageal emptying post-pneumatic dilation: use of the timed barium esophagram

OBJECTIVES

The reported success rate of pneumatic dilation in patients with achalasia varies from 50% to 93%. This wide variability may be due to using symptom relief post-dilation as the only assessment of success. There are no studies comparing subjective symptom improvements to objective improvement in esophageal emptying after pneumatic dilation.

METHODS

Patients with achalasia undergoing pneumatic dilation from 1995 to 1997 were evaluated. Pre- and post-dilation symptoms were recorded using a standardized scoring system. Barium column height was measured 1 min and 5 min after upright ingestion to assess esophageal emptying. Based on percentage of total symptom and barium height improvement post-dilation, patients were grouped according to one of nine outcomes; the association between subjective and objective parameters of improvement was tested.

RESULTS

A total of 37 patients underwent 53 pneumatic dilations. There was a significant association (p < 0.001) between improvement in patient symptoms and barium height. In 38 of 53 (72%) pneumatic dilations, the degree of symptom and barium height improvement was similar. Near complete symptom resolution was reported after 26 dilations. In eight of 26 (31%) patients however, there was < 50% improvement in barium height (group A). Compared with the 16 patients with 91-100% improvement in both symptoms and barium height (group B), forward stepwise regression identified age as the only difference between the two groups, with group A patients being significantly (p = 0.04) older.

CONCLUSIONS

Objective assessment of esophageal emptying pre- and post-dilation identifies an important subset of patients with poor esophageal emptying who report near complete symptom resolution. This group may benefit from any early repeat pneumatic dilation.

Esophagectomy with gastric reconstruction for achalasia

PURPOSE

Achalasia is a degenerative esophageal disorder that may result in esophageal failure necessitating resection for restoration of gastrointestinal function. This study evaluates a protocol of esophageal resection and gastric reconstruction for end-stage achalasia.

METHODS

Hospital records, radiographic studies, and resection specimens of patients undergoing esophagectomy and gastric reconstruction were reviewed. Patient outcome was defined by an evaluation of symptoms (early satiety, dysphagia, regurgitation, and reflux), dietary restrictions, and ability to maintain or gain weight. Preoperative, operative, and postoperative variables and pathologic features in the resection specimens were analyzed to determine predictors of outcome.

RESULTS

In a 10-year period, 32 patients underwent esophagectomy with gastric reconstruction for achalasia; 30 (94%) underwent elective surgery and 2 (6%), emergency surgery. No postoperative deaths occurred. Of 29 patients completing telephone interviews, 24 (83%) had no or mild dysphagia; 21 (72%), no or mild regurgitation; 20 (69%), no or mild reflux; and 19 (66%), no or mild early satiety. Twenty-four (83%) patients had no or minimal dietary restrictions; 26 (90%) had no or minimal social dietary restrictions. Postoperative weight was not different from preoperative weight. Of 30 patients, 26 (87%) felt better after esophagectomy and 25 (83%) would have the operation again. There were few predictors of outcome. Younger patients were more likely to have dysphagia ( P =.03).

CONCLUSIONS

Esophagectomy with gastric reconstruction relieves preoperative dysphasia and regurgitation in the majority of patients. Dietary function and weight maintenance are excellent, attesting to the durability of the procedure in patients with end-stage achalasia.

A common ancestor for a subunit in the mitochondrial proton-translocating NADH:ubiquinone oxidoreductase (complex I) and short-chain dehydrogenases/reductases

The proton-translocating NADH:ubiquinone oxidoreductase or complex I is located in the inner membranes of mitochondria, where it catalyzes the transfer of electrons from NADH to ubiquinone. Here we report that one of the subunits in complex I is homologous to short-chain dehydrogenases and reductases, a family of enzymes with diverse activities that include metabolizing steroids, prostaglandins and nucleotide sugars. We discovered that a subunit of complex I in human, cow, Neurospora crassa and Aquifex aeolius is homologous to nucleotide-sugar epimerases and hydroxysteroid dehydrogenases while seeking distant homologs of these enzymes with a hidden Markov model-based search of Genpept. This homology allows us to use information from the solved three-dimensional structures of nucleotide-sugar epimerases and hydroxysteroid dehydrogenases and our motif analysis of these enzymes to predict functional domains on their homologs in complex I.

Comparison of two barium suspensions for dedicated small-bowel series

OBJECTIVE

The in vivo radiographic features of two commercially available formulations of barium used as contrast media in dedicated small-bowel series were compared.

SUBJECTS AND METHODS

Fifty-six consecutive outpatients referred for a dedicated small-bowel series were randomly administered either E-Z-Paque or Entrobar. Representative survey radiographs from each examination were randomized and reviewed by six gastrointestinal radiologists from three institutions. Each observer assigned a numeric score (1 = poor, 2 = fair, 3 = good, and 4 = excellent) that rated the quality of the radiograph with respect to these characteristics: definition of fold pattern, translucency, distention, and integrity of the barium column. Statistical analysis was performed for each characteristic using Wilcoxon's two-sample rank sum test.

RESULTS

All six observers found a statistically significant difference between the two barium formulations for mean scores for definition of fold pattern and translucency. Mean scores for fold pattern were 3.3, 3.0, 3.2, 3.6, 3.3, and 3.4 for Entrobar and 2.1, 2.3, 2.4, 3.2, 2.6, and 2.7 for E-Z-Paque. Mean scores for translucency were 2.5, 2.7, 2.8, 3.1, 2.7, and 3.3 for Entrobar and 1.6, 1.7, 2.1, 2.3, 1.9, and 2.7 for E-Z-Paque. No statistically significant difference was found for mean score for distention or integrity of the barium column.

CONCLUSION

On radiographs, Entrobar was found to have superior characteristics for visualization of fold pattern and translucency but offered no advantages for distention or integrity of the barium column. Improved translucency and definition of fold pattern may translate into improved sensitivity and confidence in diagnosing small-bowel abnormality.

Botulinum toxin versus pneumatic dilatation in the treatment of achalasia: a randomised trial

BACKGROUND

Intrasphincteric injection of botulinum toxin is a new treatment option for achalasia.

AIMS

To compare the immediate and long term efficacy of botulinum toxin with that of pneumatic dilatation.

METHODS

Symptomatic patients with achalasia were randomised to botulinum toxin (22 patients, median age 57 years) or pneumatic dilatation (20 patients, median age 56 years). Symptom scores were assessed initially, and at one, three, six, nine, and 12 months after treatment. Objective assessment included oesophageal manometry initially and at one month, and barium oesophagram initially and at one, six, and 12 months post-treatment.

RESULTS

Pneumatic dilatation resulted in a significantly (p=0.02) higher cumulative remission rate. At 12 months, 14/20 (70%) pneumatic dilatation and 7/22 (32%) botulinum toxin treated patients were in symptomatic remission (p=0.017). Failure rates were similar initially, but failure over time was significantly (p=0.01) higher after botulinum toxin (50%) than pneumatic dilatation (7%). Pneumatic dilatation resulted in significant (p<0.001) reduction in symptom scores, and lower oesophageal sphincter pressure, oesophageal barium column height, and oesophageal diameter. Botulinum toxin produced significant reduction in symptom scores (p<0.001), but no reduction in objective parameters.

CONCLUSIONS

At one year pneumatic dilatation is more effective than botulinum toxin. Symptom improvement parallels objective oesophageal measurements after pneumatic dilatation but not after botulinum toxin treatment for achalasia.

An NADPH-dependent reductase in neonatal pig testes that metabolizes androgens and xenobiotics

We have isolated an NADPH-dependent reductase from neonatal pig testes that metabolizes androgens and a variety of xenobiotics. This enzyme is distinct from 3alpha/beta,20beta-hydroxysteroid dehydrogenase or its homologue, carbonyl reductase, as judged by its immunological and molecular properties and its much narrower specificity for steroids. This reductase and 3alpha/beta,20beta-hydroxysteroid dehydrogenase may be part of a mechanism for regulating androgen levels the neonatal pig testes. Interestingly, we could not find multiple isoforms of 3alpha/beta,20beta-hydroxysteroid dehydrogenase/carbonyl reductase in pig testes unlike human and rat testes and other organs in which multiple isoforms are expressed.

Albumin's role in steroid hormone action and the origins of vertebrates: is albumin an essential protein?

Albumin, the major serum protein, binds a wide variety of lipophilic compounds including steroids, other lipophilic hormones and phytochemicals that bind to hormone receptors. Albumin has a low affinity for these lipophilic compounds. However, due to albumin's high concentration in serum, albumin is a major carrier of steroids and lipophilic hormones and regulator of their access to their receptors. Moreover, albumin functions as a sink for phytochemicals, which prevents their binding to hormone receptors and other cellular proteins, protecting animals from disruptive phytochemical-mediated endocrine effects. We propose that these properties of albumin were important in protochordates and vertebrates about 550 to 520 million years ago, just before and during the Cambrian. At that time, animal body sizes and exposure to phytochemicals in food were increasing, and animals in which albumin expression was high had a selective advantage in surviving and reproducing in the presence of toxic phytochemicals. This hypothesis that albumin has essential function(s) in mammalian endocrine physiology can be tested by comparing the effects of phytochemicals in Nagase rats that have 1/1000 the normal albumin concentration or in mice in which the albumin gene is knocked out with those in normal rats and mice.

Flavonoids as hormones. A perspective from an analysis of molecular fossils

Although for centuries plants have been known to have hormone-like actions in humans, the mechanism(s) by which plant-derived compounds act in humans is still being elucidated, a goal that has assumed more importance due to interest in the protective actions of fruits and vegetables in diseases such as cancer. Here I use the "molecular fossil record" of amino acid sequences of proteins involved in regulating the actions steroids, retinoids, thyroid hormone and prostaglandins to propose some mechanisms by which flavonoids in fruits and vegetables can have hormone-like actions in humans. I focus on: i) hormone receptors that bind to DNA and regulate gene transcription and ii) the enzymes that regulate the concentrations of these hormones. Comparative analyses of amino acid sequences show that nuclear receptors for steroids, retinoids, thyroid hormone and prostaglandins in humans and insects are descended from a common ancestor. Similar analyses of dehydrogenases that regulate the concentrations of steroids, retinoids and prostaglandins reveal strong sequence similarity to enzymes in plants, insects, fungi, and bacteria. The similarity is sufficient to suggest that some compounds that bind receptors or enzymes in invertebrates, plants or unicellular organisms may also bind to mammalian homologs that are involved in endocrine physiology. Among the phytochemicals that are candidates for such activity are flavonoids because they are involved in plant-insect and plant-bacteria interactions and have some structural and chemical similarities to steroids, retinoids, thyroid hormone, prostaglandins and fatty acids. These similarities and the kinship of human, plant, insect and bacterial proteins involved in signal transduction provide a conceptual framework for investigating flavonoids for hormone-like actions in humans. Understanding these modes of action may be useful in developing protocols for preventing hormone-dependent diseases such as breast and prostate cancer.

Mutation of tyrosine-194 and lysine-198 in the catalytic site of pig 3alpha/beta,20beta-hydroxysteroid dehydrogenase

Pig 3alpha/beta,20beta-hydroxysteroid dehydrogenase is an NADPH-dependent enzyme that catalyses the reduction of ketones on steroids and aldehydes and ketones on various xenobiotics, like its homologue carbonyl reductase. 3alpha/beta,20beta-Hydroxysteroid dehydrogenase and carbonyl reductase are members of the short-chain dehydrogenases/reductase family, in which a tyrosine residue and a lysine residue have been identified as catalytically important. In pig 20beta-hydroxysteroid dehydrogenase these residues are tyrosine-194 and lysine-198. Here we report the effect on the reduction of two ketone and two aldehyde substrates by pig 3alpha/beta,20beta-hydroxysteroid dehydrogenase in which tyrosine-194 has been mutated to phenylalanine and cysteine, and lysine-198 has been mutated to isoleucine and arginine. Mutants with phenylalanine-194 or isoleucine-198 are inactive. Depending on the substrate, the mutant with cysteine-194 has a catalytic efficiency of 0.4-1% and the mutant with arginine-198 has a catalytic efficiency of 4-23% of the wild-type enzyme. We also mutated tyrosine-81 and tyrosine-253 to phenylalanine. Although both tyrosines are conserved in 3alpha/beta,20beta-hydroxysteroid dehydrogenase and carbonyl reductase, depending on the substrate, the mutant enzymes are as active as, or more active than, wild-type enzyme.

Evolution of mammalian 11beta- and 17beta-hydroxysteroid dehydrogenases-type 2 and retinol dehydrogenases from ancestors in Caenorhabditis elegans and evidence for horizontal transfer of a eukaryote dehydrogenase to E. coli

Physiological responses due to steroid hormones and retinoids are regulated by their cognate receptors and dehydrogenases. The origins of either regulatory mechanism are not fully understood. Here we examine the origins of the human 11beta-hydroxysteroid dehydrogenase-type 2, which regulates access of glucocorticoids to cells, and 17beta-hydroxysteroid dehydrogenase-type 2, which regulates access of androgens and estrogens to cells. Sequence comparisons trace their ancestry to homologs in Caenorhabditis elegans. These C. elegans proteins most closely resemble mammalian all-trans and 11-cis-retinol dehydrogenases. The similarity is sufficient -37% to 43% identity to suggest that one or more of the C. elegans homologs metabolizes a retinoid. Receptors for retinoids, but not for androgens, estrogens or glucocorticoids have been identified in C. elegans, suggesting that retinoid-mediated gene transcription is more ancient than that for adrenal and sex steroids. We propose that the hydroxysteroid dehydrogenase-type 2 mechanism for regulating the androgen, estrogen and glucocorticoid concentrations in mammals descended from that for regulating retinoid concentrations. Interestingly, E. coli contains a protein with strong sequence similarity to mammalian retinol dehydrogenases. Sequence comparisons and phylogenetic analysis indicate that the E. coli protein may be an example of horizontal transfer from a eukaryote ancestor.

Characterization of Ke 6, a new 17beta-hydroxysteroid dehydrogenase, and its expression in gonadal tissues

The abnormal regulation of the Ke 6 gene has been linked to the development of recessive polycystic kidney disease in the mouse. In this report, we have shown that Ke 6 is a 17beta-hydroxysteroid dehydrogenase and can regulate the concentration of biologically active estrogens and androgens. The Ke 6 enzyme is preferentially an oxidative enzyme and inactivates estradiol, testosterone, and dihydrotestosterone. However, the enzyme has some reductive activity and can synthesize estradiol from estrone. We find that the Ke 6 gene is expressed within the ovaries and testes. The presence of Ke 6 protein within the cumulus cells surrounding the oocyte places it in a strategic location to control the level of steroids to which the egg is exposed. Previously, it had been shown that glucocorticoids can induce renal cysts in the neonatal rodent, only when given at a narrow time window of postnatal kidney development. We propose that the reduction in the level of Ke 6 enzyme, which occurs in the cpk, jck, and pcy mice, may lead to abnormal elevations in local level of sex steroids, which either directly or indirectly via abnormal glucocorticoid metabolism result in recessive renal cystic disease, a developmental disorder of the kidney.

Spinach CSP41, an mRNA-binding protein and ribonuclease, is homologous to nucleotide-sugar epimerases and hydroxysteroid dehydrogenases

Spinach CSP41 is part of a protein complex that binds to the 3' untranslated region (UTR) of petD precursor-mRNA, a chloroplast gene encoding subunit IV of the cytochrome b6/f complex. CSP41 cleaves the 3'-UTR of petD mRNA within the stem-loop structure, suggesting a key role in the control of chloroplast mRNA stability. We discovered that CSP41 is homologous to nucleotide-sugar epimerases and hydroxysteroid dehydrogenases while seeking distant homologs of these enzymes with a hidden Markov model-based search of Genpept. This analysis identified Synechocystis ORF, Accession 1652543 as a homolog. Subsequent analyses show that spinach CSP41 and Arabidopsis thaliana 2765081 are homologous to the Synechocystis ORF. Information from the solved 3D structures of epimerases and dehydrogenases and our motif analysis of these enzymes is used to predict domains on CSP41 that are important in binding and metabolism of mRNA. Cyanobacteria are among the earliest life forms, indicating that the divergence from a common ancestor of nucleotide-sugar epimerases and an mRNA binding protein with ribonuclease activity was ancient.

Flavonoids inhibit estrogen binding to rat alpha-fetoprotein

There is considerable interest in the role(s) of plant-derived compounds such as bioflavonoids in regulating steroid hormone action in mammals, and in particular, the possible effects of the bioflavonoids on the growth of steroid-dependent breast and prostate tumors and on possible abnormal development of steroid-sensitive tissues. Studies of the hormone-like actions of bioflavonoids often use fetal or neonatal rats, which contain high levels of serum alpha-fetoprotein (AFP), a protein that binds estradiol with a Kd approximately 5 x 10(-9) M. Interaction of bioflavonoids with AFP could affect the availability of estrogens to estrogen-responsive cells, as well as the actions of bioflavonoids. These considerations motivated us to study the effect of several flavonoids (quercetin, rutin, naringenin, chrysin, apigenin, kaempferol, myricetin, morin, fisetin) and isoflavonoids (daidzein, genistein) on estrogen binding to rat AFP. We found that naringenin, a flavanone, and quercetin and kaempferol, flavonols, inhibit estrogen binding to AFP with apparent Kds of about 5 x 10(-7) M. To our surprise, the two isoflavonoids, daidzein and genistein, have Kds of about 5 x 10(-6) M for AFP. This 10-fold [correction of 1Q-fold] difference in affinity for AFP between flavonoids and isoflavonoids suggests that AFP has a specificity for the flavonoid structure. Moreover, the affinities of bioflavonoids for rat AFP are sufficiently high to suggest that flavonoids and isoflavonoids could modulate estradiol and estrone binding to rat AFP in vivo, when present at dietary levels. Additionally, the potency of the plant estrogens may be altered by binding to AFP. The flavonoids that we tested have different hydroxyl and glucoside substituents on the A, B, and C rings, which allows us to define some of the spatial requirements for binding to AFP. We find that 5,7-hydroxyl groups in ring A and a 4'-hydroxyl group in ring B are important for binding to AFP. This information, combined with molecular modeling studies, may elucidate the molecular basis for recognition of flavonoids and estrogens by AFP. Also, these findings indicate that the flavonoid levels in the diet need to be considered in studies of the effects of various xenobiotics and endocrine manipulations on experimental animals, particularly during development when serum estrogen binding protein concentrations are often elevated. Finally, bioflavonoids should be useful tools for understanding the variety of estrogen actions initiated by different structural classes of estrogens.

Comparison of examination times between CT scanners: are the newer scanners faster?

OBJECTIVE

The purpose of this study was to determine if a newer technology helical CT scanner can reduce CT examination times.

MATERIALS AND METHODS

Data from 1049 CT examinations were recorded prospectively during a 5-week period. "Room time" was defined as the time each patient spent in the CT room (time patient exited minus time patient entered) and "scanner time" was defined as the time a scanner was dedicated to a specific patient (longer of either time that image processing was complete minus time patient entered room, or total time that patient spent in the scanner room). Data to calculate the room and scanner times were recorded along with the scanner type, examination protocol, and five other covariates. Both times were calculated for the 10 most common examination protocols (n = 769 patients) and compared between the older and newer model CT scanner using analysis of covariance models. The most common protocols were abdomen and pelvis (n = 211); head (n = 146); chest (n = 99); simple sinus (n = 99); and chest, abdomen, and pelvis (n = 68).

RESULTS

The mean room and scanner times, adjusted for covariates, were both significantly shorter for the newer scanner (p = .0001). The results for room time were statistically significant for six of the 10 examination protocols (84% of examinations). Likewise, the results for scanner time were statistically significant for four examination protocols (68% of examinations). Examination times were longer for inpatients (p = .0001) and when problems occurred during the examination (p = .0001). Sex and age did not significantly affect examination times (p > .08).

CONCLUSION

The newer helical CT scanner we studied significantly reduced the time for many types of examinations.

Steroid receptor phylogeny and vertebrate origins

Vertebrates appear about 500 million years ago in the fossil record. This is only 25-50 million years after the great explosion of multicellular invertebrate body plans in the early Cambrian. On a geological time scale, this interval is a 'blink of an eye', suggesting that the evolution of regulatory genes is likely to be important in the origins of vertebrates. Here we present evidence for a role of steroid receptors in this process based on a phylogenetic analysis suggesting that receptors for androgens, glucocorticoids, mineralocorticoids, and progesterone evolved from an ancestral steroid receptor gene by two successive duplications over a brief time that could have coincided with the origins of vertebrates. Moreover, the duplications of these steroid receptors may be additional evidence for the two duplications on a genome-scale that have been proposed to be important in the evolution of vertebrates. The two successive duplications of steroid receptor genes and their subsequent sequence divergence leading to steroid-specific receptors that regulate growth, development, reproduction and homeostasis in vertebrates may have been one of the events important in vertebrate survival after the Cambrian during global extinctions that occurred about 440 and 370 million years ago.

Physiological "constants" for PBPK models for pregnancy

Physiologically based pharmacokinetic (PBPK) models for pregnancy are inherently more complex than conventional PBPK models due to the growth of the maternal and embryo/fetal tissues. Physiological parameters such as compartmental volumes or flow rates are relatively constant at any particular time during gestation when an acute experiment might be conducted, but vary greatly throughout the course of gestation (e.g., contrast relative fetal weight during the first month of gestation with the ninth month). Maternal physiological parameters change during gestation, depending upon the particular system; for example, cardiac output increases by approximately 50% during human gestation; plasma protein concentration decreases during pregnancy; overall metabolism remains fairly constant. Maternal compartmental volumes may change by 10-30%; embryo/fetal volume increases over a billionfold from conception to birth. Data describing these physiological changes in the human are available from the literature. Human embryo/fetal growth can be well described using the Gompertz equation. By contrast, very little of these same types of data is available for the laboratory animal. In the rodent there is a dearth of information during organogenesis as to embryo weights, and even less organ or tissue weight or volume data during embryonic or fetal periods. Allometric modeling offers a reasonable choice to extrapolate (approximately) from humans to animals; validation, however, is confined to comparisons with limited data during the late embryonic and fetal periods of development (after gestation d 11 in the rat and mouse). Embryonic weight measurements are limited by the small size of the embryo and the current state of technology. However, the application of the laser scanning confocal microscope (LSCM) to optically section intact embryos offers the capability of precise structural measurements and computer-generated three-dimensional reconstruction of early embryos. Application of these PBPK models of pregnancy in laboratory animal models at teratogenically sensitive periods of development provides exposure values at specific target tissues. These exposures provide fundamentally important data to help design and interpret molecular probe investigations into mechanisms of teratogenesis.

MLN64 contains a domain with homology to the steroidogenic acute regulatory protein (StAR) that stimulates steroidogenesis

MLN64 is a protein that is highly expressed in certain breast carcinomas. The C terminus of MLN64 shares significant homology with the steroidogenic acute regulatory protein (StAR), which plays a key role in steroid hormone biosynthesis by enhancing the intramitochondrial translocation of cholesterol to the cholesterol side-chain cleavage enzyme. We tested the ability of MLN64 to stimulate steroidogenesis by using COS-1 cells cotransfected with plasmids expressing the human cholesterol side-chain cleavage enzyme system and wild-type and mutant MLN64 proteins. Wild-type MLN64 increased pregnenolone secretion in this system 2-fold. The steroidogenic activity of MLN64 was found to reside in the C terminus of the protein, because constructs from which the C-terminal StAR homology domain was deleted had no steroidogenic activity. In contrast, removal of N-terminal sequences increased MLN64's steroidogenesis-enhancing activity. MLN64 mRNA was found in many human tissues, including the placenta and brain, which synthesize steroid hormones but do not express StAR. Western blot analysis revealed the presence of lower molecular weight immunoreactive MLN64 species that contain the C-terminal sequences in human tissues. Homologs of both MLN64 and StAR were identified in Caenorhabditis elegans, indicating that the two proteins are ancient. Mutations that inactivate StAR were correlated with amino acid residues that are identical or similar among StAR and MLN64, indicating that conserved motifs are important for steroidogenic activity. We conclude that MLN64 stimulates steroidogenesis by virtue of its homology to StAR.

Timed barium swallow: a simple technique for evaluating esophageal emptying in patients with achalasia

OBJECTIVE

Our purpose was to define a simple technique for timing a barium swallow by which radiologists can assess esophageal emptying in patients with achalasia before and after minimally invasive therapy. Our purpose was also to determine the best method of quantifying the degree of emptying using this timed technique.

MATERIALS AND METHODS

In the barium swallow technique, upright frontal spot films of the esophagus are obtained at 1, 2, and 5 min after ingestion of 100-200 ml of low-density (45% weight in volume) barium sulfate (volume of barium determined by patient tolerance). Forty-two of these barium swallows done by 23 patients with achalasia were retrospectively reviewed. The examination served either as a baseline study or as a 1-month follow-up study after patients had undergone pneumatic dilatation or Clostridium botulinum toxin injection. The spot films were digitized, and a region of interest was drawn around the column of barium by two observers. The change in area seen in the region of interest on the 1- and 5-min films served as the gold standard for percentage of emptying. The spot films were then analyzed by four other observers, each of whom independently, subjectively, and qualitatively estimated the percentage of emptying between the 1- and 5-min spot films. Percentages were divided into quintiles. On a separate occasion, each of these four observers also independently measured the height and width of the barium column on the 1- and 5-min spot films. The product of height times width seen on the 1- and 5-min films became the quantitative estimate for percentage of emptying.

RESULTS

We found no statistically significant difference between the percentage of emptying as measured on the digitized images by the two observers and the height-times-width calculations or qualitative emptying percentage as estimated by the four observers. Interobserver agreement for the area evaluated on the digitized films as well as the height-times-width measurements and qualitative estimates of emptying was almost perfect (the correlation coefficients being 0.99, 0.87, and 0.93, respectively).

CONCLUSION

The timed barium swallow is a simple and reproducible technique. Both qualitative assessment and estimated change in area based on height-times-width measurements of the barium column are accurate methods of estimating esophageal emptying.